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systemd/src/core/exec-invoke.c

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core: move code from execute.c to exec-invoke.c No functional changes, only moving code that is only needed in exec_invoke, and adding new dependencies for seccomp/selinux/apparmor/pam in meson for the sd-executor binary.
2023-09-01 02:24:49 +01:00
/* SPDX-License-Identifier: LGPL-2.1-or-later */
#include <sys/eventfd.h>
#include <sys/ioctl.h>
#include <sys/mount.h>
#include <sys/prctl.h>
#if HAVE_PAM
#include <security/pam_appl.h>
#include <security/pam_misc.h>
#endif
#if HAVE_APPARMOR
#include <sys/apparmor.h>
#endif
#include "sd-messages.h"
#if HAVE_APPARMOR
#include "apparmor-util.h"
#endif
#include "argv-util.h"
#include "barrier.h"
#include "bpf-dlopen.h"
#include "bpf-lsm.h"
#include "btrfs-util.h"
#include "capability-util.h"
#include "cgroup-setup.h"
#include "chase.h"
#include "chattr-util.h"
#include "chown-recursive.h"
#include "copy.h"
#include "data-fd-util.h"
#include "env-util.h"
#include "escape.h"
#include "exec-credential.h"
#include "exec-invoke.h"
#include "execute.h"
#include "exit-status.h"
#include "fd-util.h"
#include "hexdecoct.h"
#include "io-util.h"
io-util: split out "struct iovec" related calls into their own .c/.h files This is preparation for #28891, which adds a bunch more helpers around "struct iovec", at which point this really deserves its own .c/.h file. The idea is that we sooner or later can consider "struct iovec" as an entirely generic mechanism to reference some binary blob, and is the go-to type for this purpose whenever we need one.
2023-10-19 16:01:38 +02:00
#include "iovec-util.h"
core: move code from execute.c to exec-invoke.c No functional changes, only moving code that is only needed in exec_invoke, and adding new dependencies for seccomp/selinux/apparmor/pam in meson for the sd-executor binary.
2023-09-01 02:24:49 +01:00
#include "missing_ioprio.h"
#include "missing_prctl.h"
#include "missing_securebits.h"
#include "missing_syscall.h"
#include "mkdir-label.h"
#include "proc-cmdline.h"
#include "process-util.h"
#include "psi-util.h"
#include "rlimit-util.h"
#include "seccomp-util.h"
#include "selinux-util.h"
#include "signal-util.h"
#include "smack-util.h"
#include "socket-util.h"
#include "string-table.h"
#include "strv.h"
#include "terminal-util.h"
#include "utmp-wtmp.h"
#define IDLE_TIMEOUT_USEC (5*USEC_PER_SEC)
#define IDLE_TIMEOUT2_USEC (1*USEC_PER_SEC)
#define SNDBUF_SIZE (8*1024*1024)
static int shift_fds(int fds[], size_t n_fds) {
if (n_fds <= 0)
return 0;
/* Modifies the fds array! (sorts it) */
assert(fds);
for (int start = 0;;) {
int restart_from = -1;
for (int i = start; i < (int) n_fds; i++) {
int nfd;
/* Already at right index? */
if (fds[i] == i+3)
continue;
nfd = fcntl(fds[i], F_DUPFD, i + 3);
if (nfd < 0)
return -errno;
safe_close(fds[i]);
fds[i] = nfd;
/* Hmm, the fd we wanted isn't free? Then
* let's remember that and try again from here */
if (nfd != i+3 && restart_from < 0)
restart_from = i;
}
if (restart_from < 0)
break;
start = restart_from;
}
return 0;
}
static int flags_fds(
const int fds[],
size_t n_socket_fds,
size_t n_fds,
bool nonblock) {
int r;
if (n_fds <= 0)
return 0;
assert(fds);
/* Drops/Sets O_NONBLOCK and FD_CLOEXEC from the file flags.
* O_NONBLOCK only applies to socket activation though. */
for (size_t i = 0; i < n_fds; i++) {
if (i < n_socket_fds) {
r = fd_nonblock(fds[i], nonblock);
if (r < 0)
return r;
}
/* We unconditionally drop FD_CLOEXEC from the fds,
* since after all we want to pass these fds to our
* children */
r = fd_cloexec(fds[i], false);
if (r < 0)
return r;
}
return 0;
}
static bool is_terminal_input(ExecInput i) {
return IN_SET(i,
EXEC_INPUT_TTY,
EXEC_INPUT_TTY_FORCE,
EXEC_INPUT_TTY_FAIL);
}
static bool is_terminal_output(ExecOutput o) {
return IN_SET(o,
EXEC_OUTPUT_TTY,
EXEC_OUTPUT_KMSG_AND_CONSOLE,
EXEC_OUTPUT_JOURNAL_AND_CONSOLE);
}
static bool is_kmsg_output(ExecOutput o) {
return IN_SET(o,
EXEC_OUTPUT_KMSG,
EXEC_OUTPUT_KMSG_AND_CONSOLE);
}
static bool exec_context_needs_term(const ExecContext *c) {
assert(c);
/* Return true if the execution context suggests we should set $TERM to something useful. */
if (is_terminal_input(c->std_input))
return true;
if (is_terminal_output(c->std_output))
return true;
if (is_terminal_output(c->std_error))
return true;
return !!c->tty_path;
}
static int open_null_as(int flags, int nfd) {
int fd;
assert(nfd >= 0);
fd = open("/dev/null", flags|O_NOCTTY);
if (fd < 0)
return -errno;
return move_fd(fd, nfd, false);
}
static int connect_journal_socket(
int fd,
const char *log_namespace,
uid_t uid,
gid_t gid) {
uid_t olduid = UID_INVALID;
gid_t oldgid = GID_INVALID;
const char *j;
int r;
j = log_namespace ?
strjoina("/run/systemd/journal.", log_namespace, "/stdout") :
"/run/systemd/journal/stdout";
if (gid_is_valid(gid)) {
oldgid = getgid();
if (setegid(gid) < 0)
return -errno;
}
if (uid_is_valid(uid)) {
olduid = getuid();
if (seteuid(uid) < 0) {
r = -errno;
goto restore_gid;
}
}
r = connect_unix_path(fd, AT_FDCWD, j);
/* If we fail to restore the uid or gid, things will likely fail later on. This should only happen if
an LSM interferes. */
if (uid_is_valid(uid))
(void) seteuid(olduid);
restore_gid:
if (gid_is_valid(gid))
(void) setegid(oldgid);
return r;
}
static int connect_logger_as(
const ExecContext *context,
const ExecParameters *params,
ExecOutput output,
const char *ident,
int nfd,
uid_t uid,
gid_t gid) {
_cleanup_close_ int fd = -EBADF;
int r;
assert(context);
assert(params);
assert(output < _EXEC_OUTPUT_MAX);
assert(ident);
assert(nfd >= 0);
fd = socket(AF_UNIX, SOCK_STREAM, 0);
if (fd < 0)
return -errno;
r = connect_journal_socket(fd, context->log_namespace, uid, gid);
if (r < 0)
return r;
if (shutdown(fd, SHUT_RD) < 0)
return -errno;
(void) fd_inc_sndbuf(fd, SNDBUF_SIZE);
if (dprintf(fd,
"%s\n"
"%s\n"
"%i\n"
"%i\n"
"%i\n"
"%i\n"
"%i\n",
context->syslog_identifier ?: ident,
params->flags & EXEC_PASS_LOG_UNIT ? params->unit_id : "",
context->syslog_priority,
!!context->syslog_level_prefix,
false,
is_kmsg_output(output),
is_terminal_output(output)) < 0)
return -errno;
return move_fd(TAKE_FD(fd), nfd, false);
}
static int open_terminal_as(const char *path, int flags, int nfd) {
int fd;
assert(path);
assert(nfd >= 0);
fd = open_terminal(path, flags | O_NOCTTY);
if (fd < 0)
return fd;
return move_fd(fd, nfd, false);
}
static int acquire_path(const char *path, int flags, mode_t mode) {
_cleanup_close_ int fd = -EBADF;
int r;
assert(path);
if (IN_SET(flags & O_ACCMODE, O_WRONLY, O_RDWR))
flags |= O_CREAT;
fd = open(path, flags|O_NOCTTY, mode);
if (fd >= 0)
return TAKE_FD(fd);
if (errno != ENXIO) /* ENXIO is returned when we try to open() an AF_UNIX file system socket on Linux */
return -errno;
/* So, it appears the specified path could be an AF_UNIX socket. Let's see if we can connect to it. */
fd = socket(AF_UNIX, SOCK_STREAM, 0);
if (fd < 0)
return -errno;
r = connect_unix_path(fd, AT_FDCWD, path);
if (IN_SET(r, -ENOTSOCK, -EINVAL))
/* Propagate initial error if we get ENOTSOCK or EINVAL, i.e. we have indication that this
* wasn't an AF_UNIX socket after all */
return -ENXIO;
if (r < 0)
return r;
if ((flags & O_ACCMODE) == O_RDONLY)
r = shutdown(fd, SHUT_WR);
else if ((flags & O_ACCMODE) == O_WRONLY)
r = shutdown(fd, SHUT_RD);
else
r = 0;
if (r < 0)
return -errno;
return TAKE_FD(fd);
}
static int fixup_input(
const ExecContext *context,
int socket_fd,
bool apply_tty_stdin) {
ExecInput std_input;
assert(context);
std_input = context->std_input;
if (is_terminal_input(std_input) && !apply_tty_stdin)
return EXEC_INPUT_NULL;
if (std_input == EXEC_INPUT_SOCKET && socket_fd < 0)
return EXEC_INPUT_NULL;
if (std_input == EXEC_INPUT_DATA && context->stdin_data_size == 0)
return EXEC_INPUT_NULL;
return std_input;
}
static int fixup_output(ExecOutput output, int socket_fd) {
if (output == EXEC_OUTPUT_SOCKET && socket_fd < 0)
return EXEC_OUTPUT_INHERIT;
return output;
}
static int setup_input(
const ExecContext *context,
const ExecParameters *params,
int socket_fd,
const int named_iofds[static 3]) {
ExecInput i;
int r;
assert(context);
assert(params);
assert(named_iofds);
if (params->stdin_fd >= 0) {
if (dup2(params->stdin_fd, STDIN_FILENO) < 0)
return -errno;
/* Try to make this the controlling tty, if it is a tty, and reset it */
if (isatty(STDIN_FILENO)) {
unsigned rows = context->tty_rows, cols = context->tty_cols;
(void) exec_context_tty_size(context, &rows, &cols);
(void) ioctl(STDIN_FILENO, TIOCSCTTY, context->std_input == EXEC_INPUT_TTY_FORCE);
(void) reset_terminal_fd(STDIN_FILENO, true);
(void) terminal_set_size_fd(STDIN_FILENO, NULL, rows, cols);
}
return STDIN_FILENO;
}
i = fixup_input(context, socket_fd, params->flags & EXEC_APPLY_TTY_STDIN);
switch (i) {
case EXEC_INPUT_NULL:
return open_null_as(O_RDONLY, STDIN_FILENO);
case EXEC_INPUT_TTY:
case EXEC_INPUT_TTY_FORCE:
case EXEC_INPUT_TTY_FAIL: {
unsigned rows, cols;
int fd;
fd = acquire_terminal(exec_context_tty_path(context),
i == EXEC_INPUT_TTY_FAIL ? ACQUIRE_TERMINAL_TRY :
i == EXEC_INPUT_TTY_FORCE ? ACQUIRE_TERMINAL_FORCE :
ACQUIRE_TERMINAL_WAIT,
USEC_INFINITY);
if (fd < 0)
return fd;
r = exec_context_tty_size(context, &rows, &cols);
if (r < 0)
return r;
r = terminal_set_size_fd(fd, exec_context_tty_path(context), rows, cols);
if (r < 0)
return r;
return move_fd(fd, STDIN_FILENO, false);
}
case EXEC_INPUT_SOCKET:
assert(socket_fd >= 0);
return RET_NERRNO(dup2(socket_fd, STDIN_FILENO));
case EXEC_INPUT_NAMED_FD:
assert(named_iofds[STDIN_FILENO] >= 0);
(void) fd_nonblock(named_iofds[STDIN_FILENO], false);
return RET_NERRNO(dup2(named_iofds[STDIN_FILENO], STDIN_FILENO));
case EXEC_INPUT_DATA: {
int fd;
fd = acquire_data_fd(context->stdin_data, context->stdin_data_size, 0);
if (fd < 0)
return fd;
return move_fd(fd, STDIN_FILENO, false);
}
case EXEC_INPUT_FILE: {
bool rw;
int fd;
assert(context->stdio_file[STDIN_FILENO]);
rw = (context->std_output == EXEC_OUTPUT_FILE && streq_ptr(context->stdio_file[STDIN_FILENO], context->stdio_file[STDOUT_FILENO])) ||
(context->std_error == EXEC_OUTPUT_FILE && streq_ptr(context->stdio_file[STDIN_FILENO], context->stdio_file[STDERR_FILENO]));
fd = acquire_path(context->stdio_file[STDIN_FILENO], rw ? O_RDWR : O_RDONLY, 0666 & ~context->umask);
if (fd < 0)
return fd;
return move_fd(fd, STDIN_FILENO, false);
}
default:
assert_not_reached();
}
}
static bool can_inherit_stderr_from_stdout(
const ExecContext *context,
ExecOutput o,
ExecOutput e) {
assert(context);
/* Returns true, if given the specified STDERR and STDOUT output we can directly dup() the stdout fd to the
* stderr fd */
if (e == EXEC_OUTPUT_INHERIT)
return true;
if (e != o)
return false;
if (e == EXEC_OUTPUT_NAMED_FD)
return streq_ptr(context->stdio_fdname[STDOUT_FILENO], context->stdio_fdname[STDERR_FILENO]);
if (IN_SET(e, EXEC_OUTPUT_FILE, EXEC_OUTPUT_FILE_APPEND, EXEC_OUTPUT_FILE_TRUNCATE))
return streq_ptr(context->stdio_file[STDOUT_FILENO], context->stdio_file[STDERR_FILENO]);
return true;
}
static int setup_output(
const ExecContext *context,
const ExecParameters *params,
int fileno,
int socket_fd,
const int named_iofds[static 3],
const char *ident,
uid_t uid,
gid_t gid,
dev_t *journal_stream_dev,
ino_t *journal_stream_ino) {
ExecOutput o;
ExecInput i;
int r;
assert(context);
assert(params);
assert(ident);
assert(journal_stream_dev);
assert(journal_stream_ino);
if (fileno == STDOUT_FILENO && params->stdout_fd >= 0) {
if (dup2(params->stdout_fd, STDOUT_FILENO) < 0)
return -errno;
return STDOUT_FILENO;
}
if (fileno == STDERR_FILENO && params->stderr_fd >= 0) {
if (dup2(params->stderr_fd, STDERR_FILENO) < 0)
return -errno;
return STDERR_FILENO;
}
i = fixup_input(context, socket_fd, params->flags & EXEC_APPLY_TTY_STDIN);
o = fixup_output(context->std_output, socket_fd);
if (fileno == STDERR_FILENO) {
ExecOutput e;
e = fixup_output(context->std_error, socket_fd);
/* This expects the input and output are already set up */
/* Don't change the stderr file descriptor if we inherit all
* the way and are not on a tty */
if (e == EXEC_OUTPUT_INHERIT &&
o == EXEC_OUTPUT_INHERIT &&
i == EXEC_INPUT_NULL &&
!is_terminal_input(context->std_input) &&
getppid() != 1)
return fileno;
/* Duplicate from stdout if possible */
if (can_inherit_stderr_from_stdout(context, o, e))
return RET_NERRNO(dup2(STDOUT_FILENO, fileno));
o = e;
} else if (o == EXEC_OUTPUT_INHERIT) {
/* If input got downgraded, inherit the original value */
if (i == EXEC_INPUT_NULL && is_terminal_input(context->std_input))
return open_terminal_as(exec_context_tty_path(context), O_WRONLY, fileno);
/* If the input is connected to anything that's not a /dev/null or a data fd, inherit that... */
if (!IN_SET(i, EXEC_INPUT_NULL, EXEC_INPUT_DATA))
return RET_NERRNO(dup2(STDIN_FILENO, fileno));
/* If we are not started from PID 1 we just inherit STDOUT from our parent process. */
if (getppid() != 1)
return fileno;
/* We need to open /dev/null here anew, to get the right access mode. */
return open_null_as(O_WRONLY, fileno);
}
switch (o) {
case EXEC_OUTPUT_NULL:
return open_null_as(O_WRONLY, fileno);
case EXEC_OUTPUT_TTY:
if (is_terminal_input(i))
return RET_NERRNO(dup2(STDIN_FILENO, fileno));
/* We don't reset the terminal if this is just about output */
return open_terminal_as(exec_context_tty_path(context), O_WRONLY, fileno);
case EXEC_OUTPUT_KMSG:
case EXEC_OUTPUT_KMSG_AND_CONSOLE:
case EXEC_OUTPUT_JOURNAL:
case EXEC_OUTPUT_JOURNAL_AND_CONSOLE:
r = connect_logger_as(context, params, o, ident, fileno, uid, gid);
if (r < 0) {
log_exec_warning_errno(context,
params,
r,
"Failed to connect %s to the journal socket, ignoring: %m",
fileno == STDOUT_FILENO ? "stdout" : "stderr");
r = open_null_as(O_WRONLY, fileno);
} else {
struct stat st;
/* If we connected this fd to the journal via a stream, patch the device/inode into the passed
* parameters, but only then. This is useful so that we can set $JOURNAL_STREAM that permits
* services to detect whether they are connected to the journal or not.
*
* If both stdout and stderr are connected to a stream then let's make sure to store the data
* about STDERR as that's usually the best way to do logging. */
if (fstat(fileno, &st) >= 0 &&
(*journal_stream_ino == 0 || fileno == STDERR_FILENO)) {
*journal_stream_dev = st.st_dev;
*journal_stream_ino = st.st_ino;
}
}
return r;
case EXEC_OUTPUT_SOCKET:
assert(socket_fd >= 0);
return RET_NERRNO(dup2(socket_fd, fileno));
case EXEC_OUTPUT_NAMED_FD:
assert(named_iofds[fileno] >= 0);
(void) fd_nonblock(named_iofds[fileno], false);
return RET_NERRNO(dup2(named_iofds[fileno], fileno));
case EXEC_OUTPUT_FILE:
case EXEC_OUTPUT_FILE_APPEND:
case EXEC_OUTPUT_FILE_TRUNCATE: {
bool rw;
int fd, flags;
assert(context->stdio_file[fileno]);
rw = context->std_input == EXEC_INPUT_FILE &&
streq_ptr(context->stdio_file[fileno], context->stdio_file[STDIN_FILENO]);
if (rw)
return RET_NERRNO(dup2(STDIN_FILENO, fileno));
flags = O_WRONLY;
if (o == EXEC_OUTPUT_FILE_APPEND)
flags |= O_APPEND;
else if (o == EXEC_OUTPUT_FILE_TRUNCATE)
flags |= O_TRUNC;
fd = acquire_path(context->stdio_file[fileno], flags, 0666 & ~context->umask);
if (fd < 0)
return fd;
return move_fd(fd, fileno, 0);
}
default:
assert_not_reached();
}
}
static int chown_terminal(int fd, uid_t uid) {
int r;
assert(fd >= 0);
/* Before we chown/chmod the TTY, let's ensure this is actually a tty */
if (isatty(fd) < 1) {
if (IN_SET(errno, EINVAL, ENOTTY))
return 0; /* not a tty */
return -errno;
}
/* This might fail. What matters are the results. */
r = fchmod_and_chown(fd, TTY_MODE, uid, GID_INVALID);
if (r < 0)
return r;
return 1;
}
static int setup_confirm_stdio(
const ExecContext *context,
const char *vc,
int *ret_saved_stdin,
int *ret_saved_stdout) {
_cleanup_close_ int fd = -EBADF, saved_stdin = -EBADF, saved_stdout = -EBADF;
unsigned rows, cols;
int r;
assert(ret_saved_stdin);
assert(ret_saved_stdout);
saved_stdin = fcntl(STDIN_FILENO, F_DUPFD, 3);
if (saved_stdin < 0)
return -errno;
saved_stdout = fcntl(STDOUT_FILENO, F_DUPFD, 3);
if (saved_stdout < 0)
return -errno;
fd = acquire_terminal(vc, ACQUIRE_TERMINAL_WAIT, DEFAULT_CONFIRM_USEC);
if (fd < 0)
return fd;
r = chown_terminal(fd, getuid());
if (r < 0)
return r;
r = reset_terminal_fd(fd, true);
if (r < 0)
return r;
r = exec_context_tty_size(context, &rows, &cols);
if (r < 0)
return r;
r = terminal_set_size_fd(fd, vc, rows, cols);
if (r < 0)
return r;
r = rearrange_stdio(fd, fd, STDERR_FILENO); /* Invalidates 'fd' also on failure */
TAKE_FD(fd);
if (r < 0)
return r;
*ret_saved_stdin = TAKE_FD(saved_stdin);
*ret_saved_stdout = TAKE_FD(saved_stdout);
return 0;
}
static void write_confirm_error_fd(int err, int fd, const char *unit_id) {
assert(err < 0);
assert(unit_id);
if (err == -ETIMEDOUT)
dprintf(fd, "Confirmation question timed out for %s, assuming positive response.\n", unit_id);
else {
errno = -err;
dprintf(fd, "Couldn't ask confirmation for %s: %m, assuming positive response.\n", unit_id);
}
}
static void write_confirm_error(int err, const char *vc, const char *unit_id) {
_cleanup_close_ int fd = -EBADF;
assert(vc);
fd = open_terminal(vc, O_WRONLY|O_NOCTTY|O_CLOEXEC);
if (fd < 0)
return;
write_confirm_error_fd(err, fd, unit_id);
}
static int restore_confirm_stdio(int *saved_stdin, int *saved_stdout) {
int r = 0;
assert(saved_stdin);
assert(saved_stdout);
release_terminal();
if (*saved_stdin >= 0)
if (dup2(*saved_stdin, STDIN_FILENO) < 0)
r = -errno;
if (*saved_stdout >= 0)
if (dup2(*saved_stdout, STDOUT_FILENO) < 0)
r = -errno;
*saved_stdin = safe_close(*saved_stdin);
*saved_stdout = safe_close(*saved_stdout);
return r;
}
enum {
CONFIRM_PRETEND_FAILURE = -1,
CONFIRM_PRETEND_SUCCESS = 0,
CONFIRM_EXECUTE = 1,
};
static bool confirm_spawn_disabled(void) {
return access("/run/systemd/confirm_spawn_disabled", F_OK) >= 0;
}
static int ask_for_confirmation(const ExecContext *context, const ExecParameters *params, const char *cmdline) {
int saved_stdout = -1, saved_stdin = -1, r;
_cleanup_free_ char *e = NULL;
char c;
assert(context);
assert(params);
/* For any internal errors, assume a positive response. */
r = setup_confirm_stdio(context, params->confirm_spawn, &saved_stdin, &saved_stdout);
if (r < 0) {
write_confirm_error(r, params->confirm_spawn, params->unit_id);
return CONFIRM_EXECUTE;
}
/* confirm_spawn might have been disabled while we were sleeping. */
if (!params->confirm_spawn || confirm_spawn_disabled()) {
r = 1;
goto restore_stdio;
}
e = ellipsize(cmdline, 60, 100);
if (!e) {
log_oom();
r = CONFIRM_EXECUTE;
goto restore_stdio;
}
for (;;) {
r = ask_char(&c, "yfshiDjcn", "Execute %s? [y, f, s – h for help] ", e);
if (r < 0) {
write_confirm_error_fd(r, STDOUT_FILENO, params->unit_id);
r = CONFIRM_EXECUTE;
goto restore_stdio;
}
switch (c) {
case 'c':
printf("Resuming normal execution.\n");
manager_disable_confirm_spawn();
r = 1;
break;
case 'D':
printf(" Unit: %s\n",
params->unit_id);
exec_context_dump(context, stdout, " ");
exec_params_dump(params, stdout, " ");
continue; /* ask again */
case 'f':
printf("Failing execution.\n");
r = CONFIRM_PRETEND_FAILURE;
break;
case 'h':
printf(" c - continue, proceed without asking anymore\n"
" D - dump, show the state of the unit\n"
" f - fail, don't execute the command and pretend it failed\n"
" h - help\n"
" i - info, show a short summary of the unit\n"
" j - jobs, show jobs that are in progress\n"
" s - skip, don't execute the command and pretend it succeeded\n"
" y - yes, execute the command\n");
continue; /* ask again */
case 'i':
printf(" Unit: %s\n"
" Command: %s\n",
params->unit_id, cmdline);
continue; /* ask again */
case 'j':
if (sigqueue(getppid(),
SIGRTMIN+18,
(const union sigval) { .sival_int = MANAGER_SIGNAL_COMMAND_DUMP_JOBS }) < 0)
return -errno;
continue; /* ask again */
case 'n':
/* 'n' was removed in favor of 'f'. */
printf("Didn't understand 'n', did you mean 'f'?\n");
continue; /* ask again */
case 's':
printf("Skipping execution.\n");
r = CONFIRM_PRETEND_SUCCESS;
break;
case 'y':
r = CONFIRM_EXECUTE;
break;
default:
assert_not_reached();
}
break;
}
restore_stdio:
restore_confirm_stdio(&saved_stdin, &saved_stdout);
return r;
}
static int get_fixed_user(
core/exec-invoke: rename parameters of get_fixed_{user,group} Follow-up for 1c9433559a40982785011aa187e2b34420a67e7e The user/group passed in could be either the name or the uid/gid.
2023-10-14 05:14:40 +08:00
const char *user_or_uid,
const char **ret_username,
core: move code from execute.c to exec-invoke.c No functional changes, only moving code that is only needed in exec_invoke, and adding new dependencies for seccomp/selinux/apparmor/pam in meson for the sd-executor binary.
2023-09-01 02:24:49 +01:00
uid_t *ret_uid,
gid_t *ret_gid,
const char **ret_home,
const char **ret_shell) {
int r;
core/exec-invoke: rename parameters of get_fixed_{user,group} Follow-up for 1c9433559a40982785011aa187e2b34420a67e7e The user/group passed in could be either the name or the uid/gid.
2023-10-14 05:14:40 +08:00
assert(user_or_uid);
assert(ret_username);
core: move code from execute.c to exec-invoke.c No functional changes, only moving code that is only needed in exec_invoke, and adding new dependencies for seccomp/selinux/apparmor/pam in meson for the sd-executor binary.
2023-09-01 02:24:49 +01:00
/* Note that we don't set $HOME or $SHELL if they are not particularly enlightening anyway
* (i.e. are "/" or "/bin/nologin"). */
core/exec-invoke: rename parameters of get_fixed_{user,group} Follow-up for 1c9433559a40982785011aa187e2b34420a67e7e The user/group passed in could be either the name or the uid/gid.
2023-10-14 05:14:40 +08:00
r = get_user_creds(&user_or_uid, ret_uid, ret_gid, ret_home, ret_shell, USER_CREDS_CLEAN);
core: move code from execute.c to exec-invoke.c No functional changes, only moving code that is only needed in exec_invoke, and adding new dependencies for seccomp/selinux/apparmor/pam in meson for the sd-executor binary.
2023-09-01 02:24:49 +01:00
if (r < 0)
return r;
core/exec-invoke: rename parameters of get_fixed_{user,group} Follow-up for 1c9433559a40982785011aa187e2b34420a67e7e The user/group passed in could be either the name or the uid/gid.
2023-10-14 05:14:40 +08:00
/* user_or_uid is normalized by get_user_creds to username */
*ret_username = user_or_uid;
core: move code from execute.c to exec-invoke.c No functional changes, only moving code that is only needed in exec_invoke, and adding new dependencies for seccomp/selinux/apparmor/pam in meson for the sd-executor binary.
2023-09-01 02:24:49 +01:00
return 0;
}
static int get_fixed_group(
core/exec-invoke: rename parameters of get_fixed_{user,group} Follow-up for 1c9433559a40982785011aa187e2b34420a67e7e The user/group passed in could be either the name or the uid/gid.
2023-10-14 05:14:40 +08:00
const char *group_or_gid,
const char **ret_groupname,
core: move code from execute.c to exec-invoke.c No functional changes, only moving code that is only needed in exec_invoke, and adding new dependencies for seccomp/selinux/apparmor/pam in meson for the sd-executor binary.
2023-09-01 02:24:49 +01:00
gid_t *ret_gid) {
int r;
core/exec-invoke: rename parameters of get_fixed_{user,group} Follow-up for 1c9433559a40982785011aa187e2b34420a67e7e The user/group passed in could be either the name or the uid/gid.
2023-10-14 05:14:40 +08:00
assert(group_or_gid);
assert(ret_groupname);
core: move code from execute.c to exec-invoke.c No functional changes, only moving code that is only needed in exec_invoke, and adding new dependencies for seccomp/selinux/apparmor/pam in meson for the sd-executor binary.
2023-09-01 02:24:49 +01:00
core/exec-invoke: rename parameters of get_fixed_{user,group} Follow-up for 1c9433559a40982785011aa187e2b34420a67e7e The user/group passed in could be either the name or the uid/gid.
2023-10-14 05:14:40 +08:00
r = get_group_creds(&group_or_gid, ret_gid, /* flags = */ 0);
core: move code from execute.c to exec-invoke.c No functional changes, only moving code that is only needed in exec_invoke, and adding new dependencies for seccomp/selinux/apparmor/pam in meson for the sd-executor binary.
2023-09-01 02:24:49 +01:00
if (r < 0)
return r;
core/exec-invoke: rename parameters of get_fixed_{user,group} Follow-up for 1c9433559a40982785011aa187e2b34420a67e7e The user/group passed in could be either the name or the uid/gid.
2023-10-14 05:14:40 +08:00
/* group_or_gid is normalized by get_group_creds to groupname */
*ret_groupname = group_or_gid;
core: move code from execute.c to exec-invoke.c No functional changes, only moving code that is only needed in exec_invoke, and adding new dependencies for seccomp/selinux/apparmor/pam in meson for the sd-executor binary.
2023-09-01 02:24:49 +01:00
return 0;
}
static int get_supplementary_groups(const ExecContext *c, const char *user,
const char *group, gid_t gid,
gid_t **supplementary_gids, int *ngids) {
int r, k = 0;
int ngroups_max;
bool keep_groups = false;
gid_t *groups = NULL;
_cleanup_free_ gid_t *l_gids = NULL;
assert(c);
/*
* If user is given, then lookup GID and supplementary groups list.
* We avoid NSS lookups for gid=0. Also we have to initialize groups
* here and as early as possible so we keep the list of supplementary
* groups of the caller.
*/
if (user && gid_is_valid(gid) && gid != 0) {
/* First step, initialize groups from /etc/groups */
if (initgroups(user, gid) < 0)
return -errno;
keep_groups = true;
}
if (strv_isempty(c->supplementary_groups))
return 0;
/*
* If SupplementaryGroups= was passed then NGROUPS_MAX has to
* be positive, otherwise fail.
*/
errno = 0;
ngroups_max = (int) sysconf(_SC_NGROUPS_MAX);
if (ngroups_max <= 0)
return errno_or_else(EOPNOTSUPP);
l_gids = new(gid_t, ngroups_max);
if (!l_gids)
return -ENOMEM;
if (keep_groups) {
/*
* Lookup the list of groups that the user belongs to, we
* avoid NSS lookups here too for gid=0.
*/
k = ngroups_max;
if (getgrouplist(user, gid, l_gids, &k) < 0)
return -EINVAL;
} else
k = 0;
STRV_FOREACH(i, c->supplementary_groups) {
const char *g;
if (k >= ngroups_max)
return -E2BIG;
g = *i;
r = get_group_creds(&g, l_gids+k, 0);
if (r < 0)
return r;
k++;
}
/*
* Sets ngids to zero to drop all supplementary groups, happens
* when we are under root and SupplementaryGroups= is empty.
*/
if (k == 0) {
*ngids = 0;
return 0;
}
/* Otherwise get the final list of supplementary groups */
groups = memdup(l_gids, sizeof(gid_t) * k);
if (!groups)
return -ENOMEM;
*supplementary_gids = groups;
*ngids = k;
groups = NULL;
return 0;
}
static int enforce_groups(gid_t gid, const gid_t *supplementary_gids, int ngids) {
int r;
/* Handle SupplementaryGroups= if it is not empty */
if (ngids > 0) {
r = maybe_setgroups(ngids, supplementary_gids);
if (r < 0)
return r;
}
if (gid_is_valid(gid)) {
/* Then set our gids */
if (setresgid(gid, gid, gid) < 0)
return -errno;
}
return 0;
}
static int set_securebits(unsigned bits, unsigned mask) {
unsigned applied;
int current;
current = prctl(PR_GET_SECUREBITS);
if (current < 0)
return -errno;
/* Clear all securebits defined in mask and set bits */
applied = ((unsigned) current & ~mask) | bits;
if ((unsigned) current == applied)
return 0;
if (prctl(PR_SET_SECUREBITS, applied) < 0)
return -errno;
return 1;
}
static int enforce_user(
const ExecContext *context,
uid_t uid,
uint64_t capability_ambient_set) {
assert(context);
int r;
if (!uid_is_valid(uid))
return 0;
/* Sets (but doesn't look up) the UIS and makes sure we keep the capabilities while doing so. For
* setting secure bits the capability CAP_SETPCAP is required, so we also need keep-caps in this
* case. */
if ((capability_ambient_set != 0 || context->secure_bits != 0) && uid != 0) {
/* First step: If we need to keep capabilities but drop privileges we need to make sure we
* keep our caps, while we drop privileges. Add KEEP_CAPS to the securebits */
r = set_securebits(1U << SECURE_KEEP_CAPS, 0);
if (r < 0)
return r;
}
/* Second step: actually set the uids */
if (setresuid(uid, uid, uid) < 0)
return -errno;
/* At this point we should have all necessary capabilities but are otherwise a normal user. However,
* the caps might got corrupted due to the setresuid() so we need clean them up later. This is done
* outside of this call. */
return 0;
}
#if HAVE_PAM
static int null_conv(
int num_msg,
const struct pam_message **msg,
struct pam_response **resp,
void *appdata_ptr) {
/* We don't support conversations */
return PAM_CONV_ERR;
}
#endif
static int setup_pam(
const char *name,
const char *user,
uid_t uid,
gid_t gid,
const char *tty,
char ***env, /* updated on success */
const int fds[], size_t n_fds) {
#if HAVE_PAM
static const struct pam_conv conv = {
.conv = null_conv,
.appdata_ptr = NULL
};
_cleanup_(barrier_destroy) Barrier barrier = BARRIER_NULL;
_cleanup_strv_free_ char **e = NULL;
pam_handle_t *handle = NULL;
sigset_t old_ss;
int pam_code = PAM_SUCCESS, r;
bool close_session = false;
pid_t pam_pid = 0, parent_pid;
int flags = 0;
assert(name);
assert(user);
assert(env);
/* We set up PAM in the parent process, then fork. The child
* will then stay around until killed via PR_GET_PDEATHSIG or
* systemd via the cgroup logic. It will then remove the PAM
* session again. The parent process will exec() the actual
* daemon. We do things this way to ensure that the main PID
* of the daemon is the one we initially fork()ed. */
r = barrier_create(&barrier);
if (r < 0)
goto fail;
if (log_get_max_level() < LOG_DEBUG)
flags |= PAM_SILENT;
pam_code = pam_start(name, user, &conv, &handle);
if (pam_code != PAM_SUCCESS) {
handle = NULL;
goto fail;
}
if (!tty) {
_cleanup_free_ char *q = NULL;
/* Hmm, so no TTY was explicitly passed, but an fd passed to us directly might be a TTY. Let's figure
* out if that's the case, and read the TTY off it. */
if (getttyname_malloc(STDIN_FILENO, &q) >= 0)
tty = strjoina("/dev/", q);
}
if (tty) {
pam_code = pam_set_item(handle, PAM_TTY, tty);
if (pam_code != PAM_SUCCESS)
goto fail;
}
STRV_FOREACH(nv, *env) {
pam_code = pam_putenv(handle, *nv);
if (pam_code != PAM_SUCCESS)
goto fail;
}
pam_code = pam_acct_mgmt(handle, flags);
if (pam_code != PAM_SUCCESS)
goto fail;
pam_code = pam_setcred(handle, PAM_ESTABLISH_CRED | flags);
if (pam_code != PAM_SUCCESS)
log_debug("pam_setcred() failed, ignoring: %s", pam_strerror(handle, pam_code));
pam_code = pam_open_session(handle, flags);
if (pam_code != PAM_SUCCESS)
goto fail;
close_session = true;
e = pam_getenvlist(handle);
if (!e) {
pam_code = PAM_BUF_ERR;
goto fail;
}
/* Block SIGTERM, so that we know that it won't get lost in the child */
assert_se(sigprocmask_many(SIG_BLOCK, &old_ss, SIGTERM, -1) >= 0);
parent_pid = getpid_cached();
r = safe_fork("(sd-pam)", 0, &pam_pid);
if (r < 0)
goto fail;
if (r == 0) {
int sig, ret = EXIT_PAM;
/* The child's job is to reset the PAM session on termination */
barrier_set_role(&barrier, BARRIER_CHILD);
/* Make sure we don't keep open the passed fds in this child. We assume that otherwise only
* those fds are open here that have been opened by PAM. */
(void) close_many(fds, n_fds);
/* Drop privileges - we don't need any to pam_close_session and this will make
* PR_SET_PDEATHSIG work in most cases. If this fails, ignore the error - but expect sd-pam
* threads to fail to exit normally */
r = maybe_setgroups(0, NULL);
if (r < 0)
log_warning_errno(r, "Failed to setgroups() in sd-pam: %m");
if (setresgid(gid, gid, gid) < 0)
log_warning_errno(errno, "Failed to setresgid() in sd-pam: %m");
if (setresuid(uid, uid, uid) < 0)
log_warning_errno(errno, "Failed to setresuid() in sd-pam: %m");
(void) ignore_signals(SIGPIPE);
/* Wait until our parent died. This will only work if the above setresuid() succeeds,
* otherwise the kernel will not allow unprivileged parents kill their privileged children
* this way. We rely on the control groups kill logic to do the rest for us. */
if (prctl(PR_SET_PDEATHSIG, SIGTERM) < 0)
goto child_finish;
/* Tell the parent that our setup is done. This is especially important regarding dropping
* privileges. Otherwise, unit setup might race against our setresuid(2) call.
*
* If the parent aborted, we'll detect this below, hence ignore return failure here. */
(void) barrier_place(&barrier);
/* Check if our parent process might already have died? */
if (getppid() == parent_pid) {
sigset_t ss;
assert_se(sigemptyset(&ss) >= 0);
assert_se(sigaddset(&ss, SIGTERM) >= 0);
for (;;) {
if (sigwait(&ss, &sig) < 0) {
if (errno == EINTR)
continue;
goto child_finish;
}
assert(sig == SIGTERM);
break;
}
}
pam_code = pam_setcred(handle, PAM_DELETE_CRED | flags);
if (pam_code != PAM_SUCCESS)
goto child_finish;
/* If our parent died we'll end the session */
if (getppid() != parent_pid) {
pam_code = pam_close_session(handle, flags);
if (pam_code != PAM_SUCCESS)
goto child_finish;
}
ret = 0;
child_finish:
/* NB: pam_end() when called in child processes should set PAM_DATA_SILENT to let the module
* know about this. See pam_end(3) */
(void) pam_end(handle, pam_code | flags | PAM_DATA_SILENT);
_exit(ret);
}
barrier_set_role(&barrier, BARRIER_PARENT);
/* If the child was forked off successfully it will do all the cleanups, so forget about the handle
* here. */
handle = NULL;
/* Unblock SIGTERM again in the parent */
assert_se(sigprocmask(SIG_SETMASK, &old_ss, NULL) >= 0);
/* We close the log explicitly here, since the PAM modules might have opened it, but we don't want
* this fd around. */
closelog();
/* Synchronously wait for the child to initialize. We don't care for errors as we cannot
* recover. However, warn loudly if it happens. */
if (!barrier_place_and_sync(&barrier))
log_error("PAM initialization failed");
return strv_free_and_replace(*env, e);
fail:
if (pam_code != PAM_SUCCESS) {
log_error("PAM failed: %s", pam_strerror(handle, pam_code));
r = -EPERM; /* PAM errors do not map to errno */
} else
log_error_errno(r, "PAM failed: %m");
if (handle) {
if (close_session)
pam_code = pam_close_session(handle, flags);
(void) pam_end(handle, pam_code | flags);
}
closelog();
return r;
#else
return 0;
#endif
}
static void rename_process_from_path(const char *path) {
_cleanup_free_ char *buf = NULL;
const char *p;
assert(path);
/* This resulting string must fit in 10 chars (i.e. the length of "/sbin/init") to look pretty in
* /bin/ps */
if (path_extract_filename(path, &buf) < 0) {
rename_process("(...)");
return;
}
size_t l = strlen(buf);
if (l > 8) {
/* The end of the process name is usually more interesting, since the first bit might just be
* "systemd-" */
p = buf + l - 8;
l = 8;
} else
p = buf;
char process_name[11];
process_name[0] = '(';
memcpy(process_name+1, p, l);
process_name[1+l] = ')';
process_name[1+l+1] = 0;
rename_process(process_name);
}
static bool context_has_address_families(const ExecContext *c) {
assert(c);
return c->address_families_allow_list ||
!set_isempty(c->address_families);
}
static bool context_has_syscall_filters(const ExecContext *c) {
assert(c);
return c->syscall_allow_list ||
!hashmap_isempty(c->syscall_filter);
}
static bool context_has_syscall_logs(const ExecContext *c) {
assert(c);
return c->syscall_log_allow_list ||
!hashmap_isempty(c->syscall_log);
}
core: allow using seccomp without no_new_privs when unprivileged Until now, using any form of seccomp while being unprivileged (User=) resulted in systemd enabling no_new_privs. There's no need for doing this because: * We trust the filters we apply * If User= is set and a process wants to apply a new seccomp filter, it will need to set no_new_privs itself An example of application that might want seccomp + !no_new_privs is a program that wants to run as an unprivileged user but uses file capabilities to start a web server on a privileged port while benefitting from a restrictive seccomp profile. We now keep the privileges needed to do seccomp before calling enforce_user() and drop them after the seccomp filters are applied. If the syscall filter doesn't allow the needed syscalls to drop the privileges, we keep the previous behavior by enabling no_new_privs.
2023-11-07 11:06:56 +01:00
static bool context_has_seccomp(const ExecContext *c) {
core: move code from execute.c to exec-invoke.c No functional changes, only moving code that is only needed in exec_invoke, and adding new dependencies for seccomp/selinux/apparmor/pam in meson for the sd-executor binary.
2023-09-01 02:24:49 +01:00
/* We need NNP if we have any form of seccomp and are unprivileged */
return c->lock_personality ||
c->memory_deny_write_execute ||
c->private_devices ||
c->protect_clock ||
c->protect_hostname ||
c->protect_kernel_tunables ||
c->protect_kernel_modules ||
c->protect_kernel_logs ||
context_has_address_families(c) ||
exec_context_restrict_namespaces_set(c) ||
c->restrict_realtime ||
c->restrict_suid_sgid ||
!set_isempty(c->syscall_archs) ||
context_has_syscall_filters(c) ||
context_has_syscall_logs(c);
}
core: allow using seccomp without no_new_privs when unprivileged Until now, using any form of seccomp while being unprivileged (User=) resulted in systemd enabling no_new_privs. There's no need for doing this because: * We trust the filters we apply * If User= is set and a process wants to apply a new seccomp filter, it will need to set no_new_privs itself An example of application that might want seccomp + !no_new_privs is a program that wants to run as an unprivileged user but uses file capabilities to start a web server on a privileged port while benefitting from a restrictive seccomp profile. We now keep the privileges needed to do seccomp before calling enforce_user() and drop them after the seccomp filters are applied. If the syscall filter doesn't allow the needed syscalls to drop the privileges, we keep the previous behavior by enabling no_new_privs.
2023-11-07 11:06:56 +01:00
static bool context_has_no_new_privileges(const ExecContext *c) {
assert(c);
if (c->no_new_privileges)
return true;
if (have_effective_cap(CAP_SYS_ADMIN) > 0) /* if we are privileged, we don't need NNP */
return false;
return context_has_seccomp(c);
}
core: move code from execute.c to exec-invoke.c No functional changes, only moving code that is only needed in exec_invoke, and adding new dependencies for seccomp/selinux/apparmor/pam in meson for the sd-executor binary.
2023-09-01 02:24:49 +01:00
#if HAVE_SECCOMP
core: allow using seccomp without no_new_privs when unprivileged Until now, using any form of seccomp while being unprivileged (User=) resulted in systemd enabling no_new_privs. There's no need for doing this because: * We trust the filters we apply * If User= is set and a process wants to apply a new seccomp filter, it will need to set no_new_privs itself An example of application that might want seccomp + !no_new_privs is a program that wants to run as an unprivileged user but uses file capabilities to start a web server on a privileged port while benefitting from a restrictive seccomp profile. We now keep the privileges needed to do seccomp before calling enforce_user() and drop them after the seccomp filters are applied. If the syscall filter doesn't allow the needed syscalls to drop the privileges, we keep the previous behavior by enabling no_new_privs.
2023-11-07 11:06:56 +01:00
static bool seccomp_allows_drop_privileges(const ExecContext *c) {
void *id, *val;
bool has_capget = false, has_capset = false, has_prctl = false;
assert(c);
/* No syscall filter, we are allowed to drop privileges */
if (hashmap_isempty(c->syscall_filter))
return true;
HASHMAP_FOREACH_KEY(val, id, c->syscall_filter) {
_cleanup_free_ char *name = NULL;
name = seccomp_syscall_resolve_num_arch(SCMP_ARCH_NATIVE, PTR_TO_INT(id) - 1);
if (streq(name, "capget"))
has_capget = true;
else if (streq(name, "capset"))
has_capset = true;
else if (streq(name, "prctl"))
has_prctl = true;
}
if (c->syscall_allow_list)
return has_capget && has_capset && has_prctl;
else
return !(has_capget || has_capset || has_prctl);
}
core: move code from execute.c to exec-invoke.c No functional changes, only moving code that is only needed in exec_invoke, and adding new dependencies for seccomp/selinux/apparmor/pam in meson for the sd-executor binary.
2023-09-01 02:24:49 +01:00
static bool skip_seccomp_unavailable(const ExecContext *c, const ExecParameters *p, const char* msg) {
if (is_seccomp_available())
return false;
log_exec_debug(c, p, "SECCOMP features not detected in the kernel, skipping %s", msg);
return true;
}
static int apply_syscall_filter(const ExecContext *c, const ExecParameters *p, bool needs_ambient_hack) {
uint32_t negative_action, default_action, action;
int r;
assert(c);
assert(p);
if (!context_has_syscall_filters(c))
return 0;
if (skip_seccomp_unavailable(c, p, "SystemCallFilter="))
return 0;
negative_action = c->syscall_errno == SECCOMP_ERROR_NUMBER_KILL ? scmp_act_kill_process() : SCMP_ACT_ERRNO(c->syscall_errno);
if (c->syscall_allow_list) {
default_action = negative_action;
action = SCMP_ACT_ALLOW;
} else {
default_action = SCMP_ACT_ALLOW;
action = negative_action;
}
if (needs_ambient_hack) {
r = seccomp_filter_set_add(c->syscall_filter, c->syscall_allow_list, syscall_filter_sets + SYSCALL_FILTER_SET_SETUID);
if (r < 0)
return r;
}
return seccomp_load_syscall_filter_set_raw(default_action, c->syscall_filter, action, false);
}
static int apply_syscall_log(const ExecContext *c, const ExecParameters *p) {
#ifdef SCMP_ACT_LOG
uint32_t default_action, action;
#endif
assert(c);
assert(p);
if (!context_has_syscall_logs(c))
return 0;
#ifdef SCMP_ACT_LOG
if (skip_seccomp_unavailable(c, p, "SystemCallLog="))
return 0;
if (c->syscall_log_allow_list) {
/* Log nothing but the ones listed */
default_action = SCMP_ACT_ALLOW;
action = SCMP_ACT_LOG;
} else {
/* Log everything but the ones listed */
default_action = SCMP_ACT_LOG;
action = SCMP_ACT_ALLOW;
}
return seccomp_load_syscall_filter_set_raw(default_action, c->syscall_log, action, false);
#else
/* old libseccomp */
log_exec_debug(c, p, "SECCOMP feature SCMP_ACT_LOG not available, skipping SystemCallLog=");
return 0;
#endif
}
static int apply_syscall_archs(const ExecContext *c, const ExecParameters *p) {
assert(c);
assert(p);
if (set_isempty(c->syscall_archs))
return 0;
if (skip_seccomp_unavailable(c, p, "SystemCallArchitectures="))
return 0;
return seccomp_restrict_archs(c->syscall_archs);
}
static int apply_address_families(const ExecContext *c, const ExecParameters *p) {
assert(c);
assert(p);
if (!context_has_address_families(c))
return 0;
if (skip_seccomp_unavailable(c, p, "RestrictAddressFamilies="))
return 0;
return seccomp_restrict_address_families(c->address_families, c->address_families_allow_list);
}
static int apply_memory_deny_write_execute(const ExecContext *c, const ExecParameters *p) {
int r;
assert(c);
assert(p);
if (!c->memory_deny_write_execute)
return 0;
/* use prctl() if kernel supports it (6.3) */
r = prctl(PR_SET_MDWE, PR_MDWE_REFUSE_EXEC_GAIN, 0, 0, 0);
if (r == 0) {
log_exec_debug(c, p, "Enabled MemoryDenyWriteExecute= with PR_SET_MDWE");
return 0;
}
if (r < 0 && errno != EINVAL)
return log_exec_debug_errno(c,
p,
errno,
"Failed to enable MemoryDenyWriteExecute= with PR_SET_MDWE: %m");
/* else use seccomp */
log_exec_debug(c, p, "Kernel doesn't support PR_SET_MDWE: falling back to seccomp");
if (skip_seccomp_unavailable(c, p, "MemoryDenyWriteExecute="))
return 0;
return seccomp_memory_deny_write_execute();
}
static int apply_restrict_realtime(const ExecContext *c, const ExecParameters *p) {
assert(c);
assert(p);
if (!c->restrict_realtime)
return 0;
if (skip_seccomp_unavailable(c, p, "RestrictRealtime="))
return 0;
return seccomp_restrict_realtime();
}
static int apply_restrict_suid_sgid(const ExecContext *c, const ExecParameters *p) {
assert(c);
assert(p);
if (!c->restrict_suid_sgid)
return 0;
if (skip_seccomp_unavailable(c, p, "RestrictSUIDSGID="))
return 0;
return seccomp_restrict_suid_sgid();
}
static int apply_protect_sysctl(const ExecContext *c, const ExecParameters *p) {
assert(c);
assert(p);
/* Turn off the legacy sysctl() system call. Many distributions turn this off while building the kernel, but
* let's protect even those systems where this is left on in the kernel. */
if (!c->protect_kernel_tunables)
return 0;
if (skip_seccomp_unavailable(c, p, "ProtectKernelTunables="))
return 0;
return seccomp_protect_sysctl();
}
static int apply_protect_kernel_modules(const ExecContext *c, const ExecParameters *p) {
assert(c);
assert(p);
/* Turn off module syscalls on ProtectKernelModules=yes */
if (!c->protect_kernel_modules)
return 0;
if (skip_seccomp_unavailable(c, p, "ProtectKernelModules="))
return 0;
return seccomp_load_syscall_filter_set(SCMP_ACT_ALLOW, syscall_filter_sets + SYSCALL_FILTER_SET_MODULE, SCMP_ACT_ERRNO(EPERM), false);
}
static int apply_protect_kernel_logs(const ExecContext *c, const ExecParameters *p) {
assert(c);
assert(p);
if (!c->protect_kernel_logs)
return 0;
if (skip_seccomp_unavailable(c, p, "ProtectKernelLogs="))
return 0;
return seccomp_protect_syslog();
}
static int apply_protect_clock(const ExecContext *c, const ExecParameters *p) {
assert(c);
assert(p);
if (!c->protect_clock)
return 0;
if (skip_seccomp_unavailable(c, p, "ProtectClock="))
return 0;
return seccomp_load_syscall_filter_set(SCMP_ACT_ALLOW, syscall_filter_sets + SYSCALL_FILTER_SET_CLOCK, SCMP_ACT_ERRNO(EPERM), false);
}
static int apply_private_devices(const ExecContext *c, const ExecParameters *p) {
assert(c);
assert(p);
/* If PrivateDevices= is set, also turn off iopl and all @raw-io syscalls. */
if (!c->private_devices)
return 0;
if (skip_seccomp_unavailable(c, p, "PrivateDevices="))
return 0;
return seccomp_load_syscall_filter_set(SCMP_ACT_ALLOW, syscall_filter_sets + SYSCALL_FILTER_SET_RAW_IO, SCMP_ACT_ERRNO(EPERM), false);
}
static int apply_restrict_namespaces(const ExecContext *c, const ExecParameters *p) {
assert(c);
assert(p);
if (!exec_context_restrict_namespaces_set(c))
return 0;
if (skip_seccomp_unavailable(c, p, "RestrictNamespaces="))
return 0;
return seccomp_restrict_namespaces(c->restrict_namespaces);
}
static int apply_lock_personality(const ExecContext *c, const ExecParameters *p) {
unsigned long personality;
int r;
assert(c);
assert(p);
if (!c->lock_personality)
return 0;
if (skip_seccomp_unavailable(c, p, "LockPersonality="))
return 0;
personality = c->personality;
/* If personality is not specified, use either PER_LINUX or PER_LINUX32 depending on what is currently set. */
if (personality == PERSONALITY_INVALID) {
r = opinionated_personality(&personality);
if (r < 0)
return r;
}
return seccomp_lock_personality(personality);
}
#endif
#if HAVE_LIBBPF
static int apply_restrict_filesystems(const ExecContext *c, const ExecParameters *p) {
int r;
assert(c);
assert(p);
if (!exec_context_restrict_filesystems_set(c))
return 0;
if (p->bpf_outer_map_fd < 0) {
/* LSM BPF is unsupported or lsm_bpf_setup failed */
log_exec_debug(c, p, "LSM BPF not supported, skipping RestrictFileSystems=");
return 0;
}
/* We are in a new binary, so dl-open again */
r = dlopen_bpf();
if (r < 0)
return r;
return lsm_bpf_restrict_filesystems(c->restrict_filesystems, p->cgroup_id, p->bpf_outer_map_fd, c->restrict_filesystems_allow_list);
}
#endif
static int apply_protect_hostname(const ExecContext *c, const ExecParameters *p, int *ret_exit_status) {
assert(c);
assert(p);
if (!c->protect_hostname)
return 0;
if (ns_type_supported(NAMESPACE_UTS)) {
if (unshare(CLONE_NEWUTS) < 0) {
if (!ERRNO_IS_NOT_SUPPORTED(errno) && !ERRNO_IS_PRIVILEGE(errno)) {
*ret_exit_status = EXIT_NAMESPACE;
return log_exec_error_errno(c,
p,
errno,
"Failed to set up UTS namespacing: %m");
}
log_exec_warning(c,
p,
"ProtectHostname=yes is configured, but UTS namespace setup is "
"prohibited (container manager?), ignoring namespace setup.");
}
} else
log_exec_warning(c,
p,
"ProtectHostname=yes is configured, but the kernel does not "
"support UTS namespaces, ignoring namespace setup.");
#if HAVE_SECCOMP
int r;
if (skip_seccomp_unavailable(c, p, "ProtectHostname="))
return 0;
r = seccomp_protect_hostname();
if (r < 0) {
*ret_exit_status = EXIT_SECCOMP;
return log_exec_error_errno(c, p, r, "Failed to apply hostname restrictions: %m");
}
#endif
return 0;
}
static void do_idle_pipe_dance(int idle_pipe[static 4]) {
assert(idle_pipe);
idle_pipe[1] = safe_close(idle_pipe[1]);
idle_pipe[2] = safe_close(idle_pipe[2]);
if (idle_pipe[0] >= 0) {
int r;
r = fd_wait_for_event(idle_pipe[0], POLLHUP, IDLE_TIMEOUT_USEC);
if (idle_pipe[3] >= 0 && r == 0 /* timeout */) {
ssize_t n;
/* Signal systemd that we are bored and want to continue. */
n = write(idle_pipe[3], "x", 1);
if (n > 0)
/* Wait for systemd to react to the signal above. */
(void) fd_wait_for_event(idle_pipe[0], POLLHUP, IDLE_TIMEOUT2_USEC);
}
idle_pipe[0] = safe_close(idle_pipe[0]);
}
idle_pipe[3] = safe_close(idle_pipe[3]);
}
static const char *exec_directory_env_name_to_string(ExecDirectoryType t);
/* And this table also maps ExecDirectoryType, to the environment variable we pass the selected directory to
* the service payload in. */
static const char* const exec_directory_env_name_table[_EXEC_DIRECTORY_TYPE_MAX] = {
[EXEC_DIRECTORY_RUNTIME] = "RUNTIME_DIRECTORY",
[EXEC_DIRECTORY_STATE] = "STATE_DIRECTORY",
[EXEC_DIRECTORY_CACHE] = "CACHE_DIRECTORY",
[EXEC_DIRECTORY_LOGS] = "LOGS_DIRECTORY",
[EXEC_DIRECTORY_CONFIGURATION] = "CONFIGURATION_DIRECTORY",
};
DEFINE_PRIVATE_STRING_TABLE_LOOKUP_TO_STRING(exec_directory_env_name, ExecDirectoryType);
static int build_environment(
const ExecContext *c,
const ExecParameters *p,
const CGroupContext *cgroup_context,
size_t n_fds,
char **fdnames,
const char *home,
const char *username,
const char *shell,
dev_t journal_stream_dev,
ino_t journal_stream_ino,
const char *memory_pressure_path,
char ***ret) {
_cleanup_strv_free_ char **our_env = NULL;
size_t n_env = 0;
char *x;
int r;
assert(c);
assert(p);
assert(ret);
#define N_ENV_VARS 19
our_env = new0(char*, N_ENV_VARS + _EXEC_DIRECTORY_TYPE_MAX);
if (!our_env)
return -ENOMEM;
if (n_fds > 0) {
_cleanup_free_ char *joined = NULL;
if (asprintf(&x, "LISTEN_PID="PID_FMT, getpid_cached()) < 0)
return -ENOMEM;
our_env[n_env++] = x;
if (asprintf(&x, "LISTEN_FDS=%zu", n_fds) < 0)
return -ENOMEM;
our_env[n_env++] = x;
joined = strv_join(fdnames, ":");
if (!joined)
return -ENOMEM;
x = strjoin("LISTEN_FDNAMES=", joined);
if (!x)
return -ENOMEM;
our_env[n_env++] = x;
}
if ((p->flags & EXEC_SET_WATCHDOG) && p->watchdog_usec > 0) {
if (asprintf(&x, "WATCHDOG_PID="PID_FMT, getpid_cached()) < 0)
return -ENOMEM;
our_env[n_env++] = x;
if (asprintf(&x, "WATCHDOG_USEC="USEC_FMT, p->watchdog_usec) < 0)
return -ENOMEM;
our_env[n_env++] = x;
}
/* If this is D-Bus, tell the nss-systemd module, since it relies on being able to use blocking
* Varlink calls back to us for look up dynamic users in PID 1. Break the deadlock between D-Bus and
* PID 1 by disabling use of PID1' NSS interface for looking up dynamic users. */
if (p->flags & EXEC_NSS_DYNAMIC_BYPASS) {
x = strdup("SYSTEMD_NSS_DYNAMIC_BYPASS=1");
if (!x)
return -ENOMEM;
our_env[n_env++] = x;
}
/* We query "root" if this is a system unit and User= is not specified. $USER is always set. $HOME
* could cause problem for e.g. getty, since login doesn't override $HOME, and $LOGNAME and $SHELL don't
* really make much sense since we're not logged in. Hence we conditionalize the three based on
* SetLoginEnvironment= switch. */
if (!c->user && !c->dynamic_user && p->runtime_scope == RUNTIME_SCOPE_SYSTEM) {
r = get_fixed_user("root", &username, NULL, NULL, &home, &shell);
if (r < 0)
return log_exec_debug_errno(c,
p,
r,
"Failed to determine user credentials for root: %m");
}
bool set_user_login_env = c->set_login_environment >= 0 ? c->set_login_environment : (c->user || c->dynamic_user);
if (username) {
x = strjoin("USER=", username);
if (!x)
return -ENOMEM;
our_env[n_env++] = x;
if (set_user_login_env) {
x = strjoin("LOGNAME=", username);
if (!x)
return -ENOMEM;
our_env[n_env++] = x;
}
}
if (home && set_user_login_env) {
x = strjoin("HOME=", home);
if (!x)
return -ENOMEM;
path_simplify(x + 5);
our_env[n_env++] = x;
}
if (shell && set_user_login_env) {
x = strjoin("SHELL=", shell);
if (!x)
return -ENOMEM;
path_simplify(x + 6);
our_env[n_env++] = x;
}
if (!sd_id128_is_null(p->invocation_id)) {
assert(p->invocation_id_string);
x = strjoin("INVOCATION_ID=", p->invocation_id_string);
if (!x)
return -ENOMEM;
our_env[n_env++] = x;
}
if (exec_context_needs_term(c)) {
_cleanup_free_ char *cmdline = NULL;
const char *tty_path, *term = NULL;
tty_path = exec_context_tty_path(c);
/* If we are forked off PID 1 and we are supposed to operate on /dev/console, then let's try
* to inherit the $TERM set for PID 1. This is useful for containers so that the $TERM the
* container manager passes to PID 1 ends up all the way in the console login shown. */
if (path_equal_ptr(tty_path, "/dev/console") && getppid() == 1)
term = getenv("TERM");
else if (tty_path && in_charset(skip_dev_prefix(tty_path), ALPHANUMERICAL)) {
_cleanup_free_ char *key = NULL;
key = strjoin("systemd.tty.term.", skip_dev_prefix(tty_path));
if (!key)
return -ENOMEM;
r = proc_cmdline_get_key(key, 0, &cmdline);
if (r < 0)
log_exec_debug_errno(c,
p,
r,
"Failed to read %s from kernel cmdline, ignoring: %m",
key);
else if (r > 0)
term = cmdline;
}
if (!term)
term = default_term_for_tty(tty_path);
x = strjoin("TERM=", term);
if (!x)
return -ENOMEM;
our_env[n_env++] = x;
}
if (journal_stream_dev != 0 && journal_stream_ino != 0) {
if (asprintf(&x, "JOURNAL_STREAM=" DEV_FMT ":" INO_FMT, journal_stream_dev, journal_stream_ino) < 0)
return -ENOMEM;
our_env[n_env++] = x;
}
if (c->log_namespace) {
x = strjoin("LOG_NAMESPACE=", c->log_namespace);
if (!x)
return -ENOMEM;
our_env[n_env++] = x;
}
for (ExecDirectoryType t = 0; t < _EXEC_DIRECTORY_TYPE_MAX; t++) {
_cleanup_free_ char *joined = NULL;
const char *n;
if (!p->prefix[t])
continue;
if (c->directories[t].n_items == 0)
continue;
n = exec_directory_env_name_to_string(t);
if (!n)
continue;
for (size_t i = 0; i < c->directories[t].n_items; i++) {
_cleanup_free_ char *prefixed = NULL;
prefixed = path_join(p->prefix[t], c->directories[t].items[i].path);
if (!prefixed)
return -ENOMEM;
if (!strextend_with_separator(&joined, ":", prefixed))
return -ENOMEM;
}
x = strjoin(n, "=", joined);
if (!x)
return -ENOMEM;
our_env[n_env++] = x;
}
_cleanup_free_ char *creds_dir = NULL;
r = exec_context_get_credential_directory(c, p, p->unit_id, &creds_dir);
if (r < 0)
return r;
if (r > 0) {
x = strjoin("CREDENTIALS_DIRECTORY=", creds_dir);
if (!x)
return -ENOMEM;
our_env[n_env++] = x;
}
if (asprintf(&x, "SYSTEMD_EXEC_PID=" PID_FMT, getpid_cached()) < 0)
return -ENOMEM;
our_env[n_env++] = x;
if (memory_pressure_path) {
x = strjoin("MEMORY_PRESSURE_WATCH=", memory_pressure_path);
if (!x)
return -ENOMEM;
our_env[n_env++] = x;
if (cgroup_context && !path_equal(memory_pressure_path, "/dev/null")) {
_cleanup_free_ char *b = NULL, *e = NULL;
if (asprintf(&b, "%s " USEC_FMT " " USEC_FMT,
MEMORY_PRESSURE_DEFAULT_TYPE,
cgroup_context->memory_pressure_threshold_usec == USEC_INFINITY ? MEMORY_PRESSURE_DEFAULT_THRESHOLD_USEC :
CLAMP(cgroup_context->memory_pressure_threshold_usec, 1U, MEMORY_PRESSURE_DEFAULT_WINDOW_USEC),
MEMORY_PRESSURE_DEFAULT_WINDOW_USEC) < 0)
return -ENOMEM;
if (base64mem(b, strlen(b) + 1, &e) < 0)
return -ENOMEM;
x = strjoin("MEMORY_PRESSURE_WRITE=", e);
if (!x)
return -ENOMEM;
our_env[n_env++] = x;
}
}
assert(n_env < N_ENV_VARS + _EXEC_DIRECTORY_TYPE_MAX);
#undef N_ENV_VARS
*ret = TAKE_PTR(our_env);
return 0;
}
static int build_pass_environment(const ExecContext *c, char ***ret) {
_cleanup_strv_free_ char **pass_env = NULL;
size_t n_env = 0;
STRV_FOREACH(i, c->pass_environment) {
_cleanup_free_ char *x = NULL;
char *v;
v = getenv(*i);
if (!v)
continue;
x = strjoin(*i, "=", v);
if (!x)
return -ENOMEM;
if (!GREEDY_REALLOC(pass_env, n_env + 2))
return -ENOMEM;
pass_env[n_env++] = TAKE_PTR(x);
pass_env[n_env] = NULL;
}
*ret = TAKE_PTR(pass_env);
return 0;
}
static int setup_private_users(uid_t ouid, gid_t ogid, uid_t uid, gid_t gid) {
_cleanup_free_ char *uid_map = NULL, *gid_map = NULL;
fd-uitl: rename PIPE_EBADF → EBADF_PAIR, and add EBADF_TRIPLET We use it for more than just pipe() arrays. For example also for socketpair(). Hence let's give it a generic name. Also add EBADF_TRIPLET to mirror this for things like stdin/stdout/stderr arrays, which we use a bunch of times.
2023-10-26 18:45:33 +02:00
_cleanup_close_pair_ int errno_pipe[2] = EBADF_PAIR;
core: move code from execute.c to exec-invoke.c No functional changes, only moving code that is only needed in exec_invoke, and adding new dependencies for seccomp/selinux/apparmor/pam in meson for the sd-executor binary.
2023-09-01 02:24:49 +01:00
_cleanup_close_ int unshare_ready_fd = -EBADF;
_cleanup_(sigkill_waitp) pid_t pid = 0;
uint64_t c = 1;
ssize_t n;
int r;
/* Set up a user namespace and map the original UID/GID (IDs from before any user or group changes, i.e.
* the IDs from the user or system manager(s)) to itself, the selected UID/GID to itself, and everything else to
* nobody. In order to be able to write this mapping we need CAP_SETUID in the original user namespace, which
* we however lack after opening the user namespace. To work around this we fork() a temporary child process,
* which waits for the parent to create the new user namespace while staying in the original namespace. The
* child then writes the UID mapping, under full privileges. The parent waits for the child to finish and
* continues execution normally.
* For unprivileged users (i.e. without capabilities), the root to root mapping is excluded. As such, it
* does not need CAP_SETUID to write the single line mapping to itself. */
/* Can only set up multiple mappings with CAP_SETUID. */
if (have_effective_cap(CAP_SETUID) > 0 && uid != ouid && uid_is_valid(uid))
r = asprintf(&uid_map,
UID_FMT " " UID_FMT " 1\n" /* Map $OUID → $OUID */
UID_FMT " " UID_FMT " 1\n", /* Map $UID → $UID */
ouid, ouid, uid, uid);
else
r = asprintf(&uid_map,
UID_FMT " " UID_FMT " 1\n", /* Map $OUID → $OUID */
ouid, ouid);
if (r < 0)
return -ENOMEM;
/* Can only set up multiple mappings with CAP_SETGID. */
if (have_effective_cap(CAP_SETGID) > 0 && gid != ogid && gid_is_valid(gid))
r = asprintf(&gid_map,
GID_FMT " " GID_FMT " 1\n" /* Map $OGID → $OGID */
GID_FMT " " GID_FMT " 1\n", /* Map $GID → $GID */
ogid, ogid, gid, gid);
else
r = asprintf(&gid_map,
GID_FMT " " GID_FMT " 1\n", /* Map $OGID -> $OGID */
ogid, ogid);
if (r < 0)
return -ENOMEM;
/* Create a communication channel so that the parent can tell the child when it finished creating the user
* namespace. */
unshare_ready_fd = eventfd(0, EFD_CLOEXEC);
if (unshare_ready_fd < 0)
return -errno;
/* Create a communication channel so that the child can tell the parent a proper error code in case it
* failed. */
if (pipe2(errno_pipe, O_CLOEXEC) < 0)
return -errno;
process-util: add new FORK_DEATHSIG_SIGKILL flag, rename FORK_DEATHSIG → FORK_DEATHSIG_SIGTERM Sometimes it makes sense to hard kill a client if we die. Let's hence add a third FORK_DEATHSIG flag for this purpose: FORK_DEATHSIG_SIGKILL. To make things less confusing this also renames FORK_DEATHSIG to FORK_DEATHSIG_SIGTERM to make clear it sends SIGTERM. We already had FORK_DEATHSIG_SIGINT, hence this makes things nicely symmetric. A bunch of users are switched over for FORK_DEATHSIG_SIGKILL where we know it's safe to abort things abruptly. This should make some kernel cases more robust, since we cannot get confused by signal masks or such. While we are at it, also fix a bunch of bugs where we didn't take FORK_DEATHSIG_SIGINT into account in safe_fork()
2023-11-02 11:04:36 +01:00
r = safe_fork("(sd-userns)", FORK_RESET_SIGNALS|FORK_DEATHSIG_SIGKILL, &pid);
core: move code from execute.c to exec-invoke.c No functional changes, only moving code that is only needed in exec_invoke, and adding new dependencies for seccomp/selinux/apparmor/pam in meson for the sd-executor binary.
2023-09-01 02:24:49 +01:00
if (r < 0)
return r;
if (r == 0) {
_cleanup_close_ int fd = -EBADF;
const char *a;
pid_t ppid;
/* Child process, running in the original user namespace. Let's update the parent's UID/GID map from
* here, after the parent opened its own user namespace. */
ppid = getppid();
errno_pipe[0] = safe_close(errno_pipe[0]);
/* Wait until the parent unshared the user namespace */
if (read(unshare_ready_fd, &c, sizeof(c)) < 0) {
r = -errno;
goto child_fail;
}
/* Disable the setgroups() system call in the child user namespace, for good. */
a = procfs_file_alloca(ppid, "setgroups");
fd = open(a, O_WRONLY|O_CLOEXEC);
if (fd < 0) {
if (errno != ENOENT) {
r = -errno;
goto child_fail;
}
/* If the file is missing the kernel is too old, let's continue anyway. */
} else {
if (write(fd, "deny\n", 5) < 0) {
r = -errno;
goto child_fail;
}
fd = safe_close(fd);
}
/* First write the GID map */
a = procfs_file_alloca(ppid, "gid_map");
fd = open(a, O_WRONLY|O_CLOEXEC);
if (fd < 0) {
r = -errno;
goto child_fail;
}
if (write(fd, gid_map, strlen(gid_map)) < 0) {
r = -errno;
goto child_fail;
}
fd = safe_close(fd);
/* The write the UID map */
a = procfs_file_alloca(ppid, "uid_map");
fd = open(a, O_WRONLY|O_CLOEXEC);
if (fd < 0) {
r = -errno;
goto child_fail;
}
if (write(fd, uid_map, strlen(uid_map)) < 0) {
r = -errno;
goto child_fail;
}
_exit(EXIT_SUCCESS);
child_fail:
(void) write(errno_pipe[1], &r, sizeof(r));
_exit(EXIT_FAILURE);
}
errno_pipe[1] = safe_close(errno_pipe[1]);
if (unshare(CLONE_NEWUSER) < 0)
return -errno;
/* Let the child know that the namespace is ready now */
if (write(unshare_ready_fd, &c, sizeof(c)) < 0)
return -errno;
/* Try to read an error code from the child */
n = read(errno_pipe[0], &r, sizeof(r));
if (n < 0)
return -errno;
if (n == sizeof(r)) { /* an error code was sent to us */
if (r < 0)
return r;
return -EIO;
}
if (n != 0) /* on success we should have read 0 bytes */
return -EIO;
r = wait_for_terminate_and_check("(sd-userns)", TAKE_PID(pid), 0);
if (r < 0)
return r;
if (r != EXIT_SUCCESS) /* If something strange happened with the child, let's consider this fatal, too */
return -EIO;
return 0;
}
static int create_many_symlinks(const char *root, const char *source, char **symlinks) {
_cleanup_free_ char *src_abs = NULL;
int r;
assert(source);
src_abs = path_join(root, source);
if (!src_abs)
return -ENOMEM;
STRV_FOREACH(dst, symlinks) {
_cleanup_free_ char *dst_abs = NULL;
dst_abs = path_join(root, *dst);
if (!dst_abs)
return -ENOMEM;
r = mkdir_parents_label(dst_abs, 0755);
if (r < 0)
return r;
r = symlink_idempotent(src_abs, dst_abs, true);
if (r < 0)
return r;
}
return 0;
}
static int setup_exec_directory(
const ExecContext *context,
const ExecParameters *params,
uid_t uid,
gid_t gid,
ExecDirectoryType type,
bool needs_mount_namespace,
int *exit_status) {
static const int exit_status_table[_EXEC_DIRECTORY_TYPE_MAX] = {
[EXEC_DIRECTORY_RUNTIME] = EXIT_RUNTIME_DIRECTORY,
[EXEC_DIRECTORY_STATE] = EXIT_STATE_DIRECTORY,
[EXEC_DIRECTORY_CACHE] = EXIT_CACHE_DIRECTORY,
[EXEC_DIRECTORY_LOGS] = EXIT_LOGS_DIRECTORY,
[EXEC_DIRECTORY_CONFIGURATION] = EXIT_CONFIGURATION_DIRECTORY,
};
int r;
assert(context);
assert(params);
assert(type >= 0 && type < _EXEC_DIRECTORY_TYPE_MAX);
assert(exit_status);
if (!params->prefix[type])
return 0;
if (params->flags & EXEC_CHOWN_DIRECTORIES) {
if (!uid_is_valid(uid))
uid = 0;
if (!gid_is_valid(gid))
gid = 0;
}
for (size_t i = 0; i < context->directories[type].n_items; i++) {
_cleanup_free_ char *p = NULL, *pp = NULL;
p = path_join(params->prefix[type], context->directories[type].items[i].path);
if (!p) {
r = -ENOMEM;
goto fail;
}
r = mkdir_parents_label(p, 0755);
if (r < 0)
goto fail;
if (IN_SET(type, EXEC_DIRECTORY_STATE, EXEC_DIRECTORY_LOGS) && params->runtime_scope == RUNTIME_SCOPE_USER) {
/* If we are in user mode, and a configuration directory exists but a state directory
* doesn't exist, then we likely are upgrading from an older systemd version that
* didn't know the more recent addition to the xdg-basedir spec: the $XDG_STATE_HOME
* directory. In older systemd versions EXEC_DIRECTORY_STATE was aliased to
* EXEC_DIRECTORY_CONFIGURATION, with the advent of $XDG_STATE_HOME is is now
* separated. If a service has both dirs configured but only the configuration dir
* exists and the state dir does not, we assume we are looking at an update
* situation. Hence, create a compatibility symlink, so that all expectations are
* met.
*
* (We also do something similar with the log directory, which still doesn't exist in
* the xdg basedir spec. We'll make it a subdir of the state dir.) */
/* this assumes the state dir is always created before the configuration dir */
assert_cc(EXEC_DIRECTORY_STATE < EXEC_DIRECTORY_LOGS);
assert_cc(EXEC_DIRECTORY_LOGS < EXEC_DIRECTORY_CONFIGURATION);
r = laccess(p, F_OK);
if (r == -ENOENT) {
_cleanup_free_ char *q = NULL;
/* OK, we know that the state dir does not exist. Let's see if the dir exists
* under the configuration hierarchy. */
if (type == EXEC_DIRECTORY_STATE)
q = path_join(params->prefix[EXEC_DIRECTORY_CONFIGURATION], context->directories[type].items[i].path);
else if (type == EXEC_DIRECTORY_LOGS)
q = path_join(params->prefix[EXEC_DIRECTORY_CONFIGURATION], "log", context->directories[type].items[i].path);
else
assert_not_reached();
if (!q) {
r = -ENOMEM;
goto fail;
}
r = laccess(q, F_OK);
if (r >= 0) {
/* It does exist! This hence looks like an update. Symlink the
* configuration directory into the state directory. */
r = symlink_idempotent(q, p, /* make_relative= */ true);
if (r < 0)
goto fail;
log_exec_notice(context, params, "Unit state directory %s missing but matching configuration directory %s exists, assuming update from systemd 253 or older, creating compatibility symlink.", p, q);
continue;
} else if (r != -ENOENT)
log_exec_warning_errno(context, params, r, "Unable to detect whether unit configuration directory '%s' exists, assuming not: %m", q);
} else if (r < 0)
log_exec_warning_errno(context, params, r, "Unable to detect whether unit state directory '%s' is missing, assuming it is: %m", p);
}
if (exec_directory_is_private(context, type)) {
/* So, here's one extra complication when dealing with DynamicUser=1 units. In that
* case we want to avoid leaving a directory around fully accessible that is owned by
* a dynamic user whose UID is later on reused. To lock this down we use the same
* trick used by container managers to prohibit host users to get access to files of
* the same UID in containers: we place everything inside a directory that has an
* access mode of 0700 and is owned root:root, so that it acts as security boundary
* for unprivileged host code. We then use fs namespacing to make this directory
* permeable for the service itself.
*
* Specifically: for a service which wants a special directory "foo/" we first create
* a directory "private/" with access mode 0700 owned by root:root. Then we place
* "foo" inside of that directory (i.e. "private/foo/"), and make "foo" a symlink to
* "private/foo". This way, privileged host users can access "foo/" as usual, but
* unprivileged host users can't look into it. Inside of the namespace of the unit
* "private/" is replaced by a more liberally accessible tmpfs, into which the host's
* "private/foo/" is mounted under the same name, thus disabling the access boundary
* for the service and making sure it only gets access to the dirs it needs but no
* others. Tricky? Yes, absolutely, but it works!
*
* Note that we don't do this for EXEC_DIRECTORY_CONFIGURATION as that's assumed not
* to be owned by the service itself.
*
* Also, note that we don't do this for EXEC_DIRECTORY_RUNTIME as that's often used
* for sharing files or sockets with other services. */
pp = path_join(params->prefix[type], "private");
if (!pp) {
r = -ENOMEM;
goto fail;
}
/* First set up private root if it doesn't exist yet, with access mode 0700 and owned by root:root */
r = mkdir_safe_label(pp, 0700, 0, 0, MKDIR_WARN_MODE);
if (r < 0)
goto fail;
if (!path_extend(&pp, context->directories[type].items[i].path)) {
r = -ENOMEM;
goto fail;
}
/* Create all directories between the configured directory and this private root, and mark them 0755 */
r = mkdir_parents_label(pp, 0755);
if (r < 0)
goto fail;
if (is_dir(p, false) > 0 &&
(laccess(pp, F_OK) == -ENOENT)) {
/* Hmm, the private directory doesn't exist yet, but the normal one exists? If so, move
* it over. Most likely the service has been upgraded from one that didn't use
* DynamicUser=1, to one that does. */
log_exec_info(context,
params,
"Found pre-existing public %s= directory %s, migrating to %s.\n"
"Apparently, service previously had DynamicUser= turned off, and has now turned it on.",
exec_directory_type_to_string(type), p, pp);
r = RET_NERRNO(rename(p, pp));
if (r < 0)
goto fail;
} else {
/* Otherwise, create the actual directory for the service */
r = mkdir_label(pp, context->directories[type].mode);
if (r < 0 && r != -EEXIST)
goto fail;
}
if (!context->directories[type].items[i].only_create) {
/* And link it up from the original place.
* Notes
* 1) If a mount namespace is going to be used, then this symlink remains on
* the host, and a new one for the child namespace will be created later.
* 2) It is not necessary to create this symlink when one of its parent
* directories is specified and already created. E.g.
* StateDirectory=foo foo/bar
* In that case, the inode points to pp and p for "foo/bar" are the same:
* pp = "/var/lib/private/foo/bar"
* p = "/var/lib/foo/bar"
* and, /var/lib/foo is a symlink to /var/lib/private/foo. So, not only
* we do not need to create the symlink, but we cannot create the symlink.
* See issue #24783. */
r = symlink_idempotent(pp, p, true);
if (r < 0)
goto fail;
}
} else {
_cleanup_free_ char *target = NULL;
if (type != EXEC_DIRECTORY_CONFIGURATION &&
readlink_and_make_absolute(p, &target) >= 0) {
_cleanup_free_ char *q = NULL, *q_resolved = NULL, *target_resolved = NULL;
/* This already exists and is a symlink? Interesting. Maybe it's one created
* by DynamicUser=1 (see above)?
*
* We do this for all directory types except for ConfigurationDirectory=,
* since they all support the private/ symlink logic at least in some
* configurations, see above. */
r = chase(target, NULL, 0, &target_resolved, NULL);
if (r < 0)
goto fail;
q = path_join(params->prefix[type], "private", context->directories[type].items[i].path);
if (!q) {
r = -ENOMEM;
goto fail;
}
/* /var/lib or friends may be symlinks. So, let's chase them also. */
r = chase(q, NULL, CHASE_NONEXISTENT, &q_resolved, NULL);
if (r < 0)
goto fail;
if (path_equal(q_resolved, target_resolved)) {
/* Hmm, apparently DynamicUser= was once turned on for this service,
* but is no longer. Let's move the directory back up. */
log_exec_info(context,
params,
"Found pre-existing private %s= directory %s, migrating to %s.\n"
"Apparently, service previously had DynamicUser= turned on, and has now turned it off.",
exec_directory_type_to_string(type), q, p);
r = RET_NERRNO(unlink(p));
if (r < 0)
goto fail;
r = RET_NERRNO(rename(q, p));
if (r < 0)
goto fail;
}
}
r = mkdir_label(p, context->directories[type].mode);
if (r < 0) {
if (r != -EEXIST)
goto fail;
if (type == EXEC_DIRECTORY_CONFIGURATION) {
struct stat st;
/* Don't change the owner/access mode of the configuration directory,
* as in the common case it is not written to by a service, and shall
* not be writable. */
r = RET_NERRNO(stat(p, &st));
if (r < 0)
goto fail;
/* Still complain if the access mode doesn't match */
if (((st.st_mode ^ context->directories[type].mode) & 07777) != 0)
log_exec_warning(context,
params,
"%s \'%s\' already exists but the mode is different. "
"(File system: %o %sMode: %o)",
exec_directory_type_to_string(type), context->directories[type].items[i].path,
st.st_mode & 07777, exec_directory_type_to_string(type), context->directories[type].mode & 07777);
continue;
}
}
}
/* Lock down the access mode (we use chmod_and_chown() to make this idempotent. We don't
* specify UID/GID here, so that path_chown_recursive() can optimize things depending on the
* current UID/GID ownership.) */
r = chmod_and_chown(pp ?: p, context->directories[type].mode, UID_INVALID, GID_INVALID);
if (r < 0)
goto fail;
/* Skip the rest (which deals with ownership) in user mode, since ownership changes are not
* available to user code anyway */
if (params->runtime_scope != RUNTIME_SCOPE_SYSTEM)
continue;
/* Then, change the ownership of the whole tree, if necessary. When dynamic users are used we
* drop the suid/sgid bits, since we really don't want SUID/SGID files for dynamic UID/GID
* assignments to exist. */
r = path_chown_recursive(pp ?: p, uid, gid, context->dynamic_user ? 01777 : 07777, AT_SYMLINK_FOLLOW);
if (r < 0)
goto fail;
}
/* If we are not going to run in a namespace, set up the symlinks - otherwise
* they are set up later, to allow configuring empty var/run/etc. */
if (!needs_mount_namespace)
for (size_t i = 0; i < context->directories[type].n_items; i++) {
r = create_many_symlinks(params->prefix[type],
context->directories[type].items[i].path,
context->directories[type].items[i].symlinks);
if (r < 0)
goto fail;
}
return 0;
fail:
*exit_status = exit_status_table[type];
return r;
}
#if ENABLE_SMACK
static int setup_smack(
const ExecParameters *params,
const ExecContext *context,
int executable_fd) {
int r;
assert(params);
assert(executable_fd >= 0);
if (context->smack_process_label) {
r = mac_smack_apply_pid(0, context->smack_process_label);
if (r < 0)
return r;
} else if (params->fallback_smack_process_label) {
_cleanup_free_ char *exec_label = NULL;
r = mac_smack_read_fd(executable_fd, SMACK_ATTR_EXEC, &exec_label);
if (r < 0 && !ERRNO_IS_XATTR_ABSENT(r))
return r;
r = mac_smack_apply_pid(0, exec_label ?: params->fallback_smack_process_label);
if (r < 0)
return r;
}
return 0;
}
#endif
static int compile_bind_mounts(
const ExecContext *context,
const ExecParameters *params,
BindMount **ret_bind_mounts,
size_t *ret_n_bind_mounts,
char ***ret_empty_directories) {
_cleanup_strv_free_ char **empty_directories = NULL;
BindMount *bind_mounts = NULL;
size_t n, h = 0;
int r;
assert(context);
assert(params);
assert(ret_bind_mounts);
assert(ret_n_bind_mounts);
assert(ret_empty_directories);
CLEANUP_ARRAY(bind_mounts, h, bind_mount_free_many);
n = context->n_bind_mounts;
for (ExecDirectoryType t = 0; t < _EXEC_DIRECTORY_TYPE_MAX; t++) {
if (!params->prefix[t])
continue;
for (size_t i = 0; i < context->directories[t].n_items; i++)
n += !context->directories[t].items[i].only_create;
}
if (n <= 0) {
*ret_bind_mounts = NULL;
*ret_n_bind_mounts = 0;
*ret_empty_directories = NULL;
return 0;
}
bind_mounts = new(BindMount, n);
if (!bind_mounts)
return -ENOMEM;
for (size_t i = 0; i < context->n_bind_mounts; i++) {
BindMount *item = context->bind_mounts + i;
_cleanup_free_ char *s = NULL, *d = NULL;
s = strdup(item->source);
if (!s)
return -ENOMEM;
d = strdup(item->destination);
if (!d)
return -ENOMEM;
bind_mounts[h++] = (BindMount) {
.source = TAKE_PTR(s),
.destination = TAKE_PTR(d),
.read_only = item->read_only,
.recursive = item->recursive,
.ignore_enoent = item->ignore_enoent,
};
}
for (ExecDirectoryType t = 0; t < _EXEC_DIRECTORY_TYPE_MAX; t++) {
if (!params->prefix[t])
continue;
if (context->directories[t].n_items == 0)
continue;
if (exec_directory_is_private(context, t) &&
!exec_context_with_rootfs(context)) {
char *private_root;
/* So this is for a dynamic user, and we need to make sure the process can access its own
* directory. For that we overmount the usually inaccessible "private" subdirectory with a
* tmpfs that makes it accessible and is empty except for the submounts we do this for. */
private_root = path_join(params->prefix[t], "private");
if (!private_root)
return -ENOMEM;
r = strv_consume(&empty_directories, private_root);
if (r < 0)
return r;
}
for (size_t i = 0; i < context->directories[t].n_items; i++) {
_cleanup_free_ char *s = NULL, *d = NULL;
/* When one of the parent directories is in the list, we cannot create the symlink
* for the child directory. See also the comments in setup_exec_directory(). */
if (context->directories[t].items[i].only_create)
continue;
if (exec_directory_is_private(context, t))
s = path_join(params->prefix[t], "private", context->directories[t].items[i].path);
else
s = path_join(params->prefix[t], context->directories[t].items[i].path);
if (!s)
return -ENOMEM;
if (exec_directory_is_private(context, t) &&
exec_context_with_rootfs(context))
/* When RootDirectory= or RootImage= are set, then the symbolic link to the private
* directory is not created on the root directory. So, let's bind-mount the directory
* on the 'non-private' place. */
d = path_join(params->prefix[t], context->directories[t].items[i].path);
else
d = strdup(s);
if (!d)
return -ENOMEM;
bind_mounts[h++] = (BindMount) {
.source = TAKE_PTR(s),
.destination = TAKE_PTR(d),
.read_only = false,
.nosuid = context->dynamic_user, /* don't allow suid/sgid when DynamicUser= is on */
.recursive = true,
.ignore_enoent = false,
};
}
}
assert(h == n);
*ret_bind_mounts = TAKE_PTR(bind_mounts);
*ret_n_bind_mounts = n;
*ret_empty_directories = TAKE_PTR(empty_directories);
return (int) n;
}
/* ret_symlinks will contain a list of pairs src:dest that describes
* the symlinks to create later on. For example, the symlinks needed
* to safely give private directories to DynamicUser=1 users. */
static int compile_symlinks(
const ExecContext *context,
const ExecParameters *params,
bool setup_os_release_symlink,
char ***ret_symlinks) {
_cleanup_strv_free_ char **symlinks = NULL;
int r;
assert(context);
assert(params);
assert(ret_symlinks);
for (ExecDirectoryType dt = 0; dt < _EXEC_DIRECTORY_TYPE_MAX; dt++) {
for (size_t i = 0; i < context->directories[dt].n_items; i++) {
_cleanup_free_ char *private_path = NULL, *path = NULL;
STRV_FOREACH(symlink, context->directories[dt].items[i].symlinks) {
_cleanup_free_ char *src_abs = NULL, *dst_abs = NULL;
src_abs = path_join(params->prefix[dt], context->directories[dt].items[i].path);
dst_abs = path_join(params->prefix[dt], *symlink);
if (!src_abs || !dst_abs)
return -ENOMEM;
r = strv_consume_pair(&symlinks, TAKE_PTR(src_abs), TAKE_PTR(dst_abs));
if (r < 0)
return r;
}
if (!exec_directory_is_private(context, dt) ||
exec_context_with_rootfs(context) ||
context->directories[dt].items[i].only_create)
continue;
private_path = path_join(params->prefix[dt], "private", context->directories[dt].items[i].path);
if (!private_path)
return -ENOMEM;
path = path_join(params->prefix[dt], context->directories[dt].items[i].path);
if (!path)
return -ENOMEM;
r = strv_consume_pair(&symlinks, TAKE_PTR(private_path), TAKE_PTR(path));
if (r < 0)
return r;
}
}
/* We make the host's os-release available via a symlink, so that we can copy it atomically
* and readers will never get a half-written version. Note that, while the paths specified here are
* absolute, when they are processed in namespace.c they will be made relative automatically, i.e.:
* 'os-release -> .os-release-stage/os-release' is what will be created. */
if (setup_os_release_symlink) {
r = strv_extend(&symlinks, "/run/host/.os-release-stage/os-release");
if (r < 0)
return r;
r = strv_extend(&symlinks, "/run/host/os-release");
if (r < 0)
return r;
}
*ret_symlinks = TAKE_PTR(symlinks);
return 0;
}
static bool insist_on_sandboxing(
const ExecContext *context,
const char *root_dir,
const char *root_image,
const BindMount *bind_mounts,
size_t n_bind_mounts) {
assert(context);
assert(n_bind_mounts == 0 || bind_mounts);
/* Checks whether we need to insist on fs namespacing. i.e. whether we have settings configured that
* would alter the view on the file system beyond making things read-only or invisible, i.e. would
* rearrange stuff in a way we cannot ignore gracefully. */
if (context->n_temporary_filesystems > 0)
return true;
if (root_dir || root_image)
return true;
if (context->n_mount_images > 0)
return true;
if (context->dynamic_user)
return true;
if (context->n_extension_images > 0 || !strv_isempty(context->extension_directories))
return true;
/* If there are any bind mounts set that don't map back onto themselves, fs namespacing becomes
* essential. */
for (size_t i = 0; i < n_bind_mounts; i++)
if (!path_equal(bind_mounts[i].source, bind_mounts[i].destination))
return true;
if (context->log_namespace)
return true;
return false;
}
static int setup_ephemeral(const ExecContext *context, ExecRuntime *runtime) {
_cleanup_close_ int fd = -EBADF;
int r;
if (!runtime || !runtime->ephemeral_copy)
return 0;
r = posix_lock(runtime->ephemeral_storage_socket[0], LOCK_EX);
if (r < 0)
return log_debug_errno(r, "Failed to lock ephemeral storage socket: %m");
CLEANUP_POSIX_UNLOCK(runtime->ephemeral_storage_socket[0]);
fd = receive_one_fd(runtime->ephemeral_storage_socket[0], MSG_PEEK|MSG_DONTWAIT);
if (fd >= 0)
/* We got an fd! That means ephemeral has already been set up, so nothing to do here. */
return 0;
if (fd != -EAGAIN)
return log_debug_errno(fd, "Failed to receive file descriptor queued on ephemeral storage socket: %m");
log_debug("Making ephemeral snapshot of %s to %s",
context->root_image ?: context->root_directory, runtime->ephemeral_copy);
if (context->root_image)
fd = copy_file(context->root_image, runtime->ephemeral_copy, O_EXCL, 0600,
COPY_LOCK_BSD|COPY_REFLINK|COPY_CRTIME);
else
fd = btrfs_subvol_snapshot_at(AT_FDCWD, context->root_directory,
AT_FDCWD, runtime->ephemeral_copy,
BTRFS_SNAPSHOT_FALLBACK_COPY |
BTRFS_SNAPSHOT_FALLBACK_DIRECTORY |
BTRFS_SNAPSHOT_RECURSIVE |
BTRFS_SNAPSHOT_LOCK_BSD);
if (fd < 0)
return log_debug_errno(fd, "Failed to snapshot %s to %s: %m",
context->root_image ?: context->root_directory, runtime->ephemeral_copy);
if (context->root_image) {
/* A root image might be subject to lots of random writes so let's try to disable COW on it
* which tends to not perform well in combination with lots of random writes.
*
* Note: btrfs actually isn't impressed by us setting the flag after making the reflink'ed
* copy, but we at least want to make the intention clear.
*/
r = chattr_fd(fd, FS_NOCOW_FL, FS_NOCOW_FL, NULL);
if (r < 0)
log_debug_errno(fd, "Failed to disable copy-on-write for %s, ignoring: %m", runtime->ephemeral_copy);
}
r = send_one_fd(runtime->ephemeral_storage_socket[1], fd, MSG_DONTWAIT);
if (r < 0)
return log_debug_errno(r, "Failed to queue file descriptor on ephemeral storage socket: %m");
return 1;
}
static int verity_settings_prepare(
VeritySettings *verity,
const char *root_image,
const void *root_hash,
size_t root_hash_size,
const char *root_hash_path,
const void *root_hash_sig,
size_t root_hash_sig_size,
const char *root_hash_sig_path,
const char *verity_data_path) {
int r;
assert(verity);
if (root_hash) {
void *d;
d = memdup(root_hash, root_hash_size);
if (!d)
return -ENOMEM;
free_and_replace(verity->root_hash, d);
verity->root_hash_size = root_hash_size;
verity->designator = PARTITION_ROOT;
}
if (root_hash_sig) {
void *d;
d = memdup(root_hash_sig, root_hash_sig_size);
if (!d)
return -ENOMEM;
free_and_replace(verity->root_hash_sig, d);
verity->root_hash_sig_size = root_hash_sig_size;
verity->designator = PARTITION_ROOT;
}
if (verity_data_path) {
r = free_and_strdup(&verity->data_path, verity_data_path);
if (r < 0)
return r;
}
r = verity_settings_load(
verity,
root_image,
root_hash_path,
root_hash_sig_path);
if (r < 0)
return log_debug_errno(r, "Failed to load root hash: %m");
return 0;
}
static int apply_mount_namespace(
ExecCommandFlags command_flags,
const ExecContext *context,
const ExecParameters *params,
ExecRuntime *runtime,
const char *memory_pressure_path,
char **error_path) {
_cleanup_(verity_settings_done) VeritySettings verity = VERITY_SETTINGS_DEFAULT;
_cleanup_strv_free_ char **empty_directories = NULL, **symlinks = NULL,
**read_write_paths_cleanup = NULL;
_cleanup_free_ char *creds_path = NULL, *incoming_dir = NULL, *propagate_dir = NULL,
*extension_dir = NULL, *host_os_release_stage = NULL;
const char *root_dir = NULL, *root_image = NULL, *tmp_dir = NULL, *var_tmp_dir = NULL;
char **read_write_paths;
bool needs_sandboxing, setup_os_release_symlink;
BindMount *bind_mounts = NULL;
size_t n_bind_mounts = 0;
int r;
assert(context);
CLEANUP_ARRAY(bind_mounts, n_bind_mounts, bind_mount_free_many);
if (params->flags & EXEC_APPLY_CHROOT) {
r = setup_ephemeral(context, runtime);
if (r < 0)
return r;
if (context->root_image)
root_image = (runtime ? runtime->ephemeral_copy : NULL) ?: context->root_image;
else
root_dir = (runtime ? runtime->ephemeral_copy : NULL) ?: context->root_directory;
}
r = compile_bind_mounts(context, params, &bind_mounts, &n_bind_mounts, &empty_directories);
if (r < 0)
return r;
/* We need to make the pressure path writable even if /sys/fs/cgroups is made read-only, as the
* service will need to write to it in order to start the notifications. */
if (context->protect_control_groups && memory_pressure_path && !streq(memory_pressure_path, "/dev/null")) {
read_write_paths_cleanup = strv_copy(context->read_write_paths);
if (!read_write_paths_cleanup)
return -ENOMEM;
r = strv_extend(&read_write_paths_cleanup, memory_pressure_path);
if (r < 0)
return r;
read_write_paths = read_write_paths_cleanup;
} else
read_write_paths = context->read_write_paths;
needs_sandboxing = (params->flags & EXEC_APPLY_SANDBOXING) && !(command_flags & EXEC_COMMAND_FULLY_PRIVILEGED);
if (needs_sandboxing) {
/* The runtime struct only contains the parent of the private /tmp, which is non-accessible
* to world users. Inside of it there's a /tmp that is sticky, and that's the one we want to
* use here. This does not apply when we are using /run/systemd/empty as fallback. */
if (context->private_tmp && runtime && runtime->shared) {
if (streq_ptr(runtime->shared->tmp_dir, RUN_SYSTEMD_EMPTY))
tmp_dir = runtime->shared->tmp_dir;
else if (runtime->shared->tmp_dir)
tmp_dir = strjoina(runtime->shared->tmp_dir, "/tmp");
if (streq_ptr(runtime->shared->var_tmp_dir, RUN_SYSTEMD_EMPTY))
var_tmp_dir = runtime->shared->var_tmp_dir;
else if (runtime->shared->var_tmp_dir)
var_tmp_dir = strjoina(runtime->shared->var_tmp_dir, "/tmp");
}
}
/* Symlinks (exec dirs, os-release) are set up after other mounts, before they are made read-only. */
setup_os_release_symlink = needs_sandboxing && exec_context_get_effective_mount_apivfs(context) && (root_dir || root_image);
r = compile_symlinks(context, params, setup_os_release_symlink, &symlinks);
if (r < 0)
return r;
if (context->mount_propagation_flag == MS_SHARED)
log_exec_debug(context,
params,
"shared mount propagation hidden by other fs namespacing unit settings: ignoring");
if (FLAGS_SET(params->flags, EXEC_WRITE_CREDENTIALS)) {
r = exec_context_get_credential_directory(context, params, params->unit_id, &creds_path);
if (r < 0)
return r;
}
if (params->runtime_scope == RUNTIME_SCOPE_SYSTEM) {
propagate_dir = path_join("/run/systemd/propagate/", params->unit_id);
if (!propagate_dir)
return -ENOMEM;
incoming_dir = strdup("/run/systemd/incoming");
if (!incoming_dir)
return -ENOMEM;
extension_dir = strdup("/run/systemd/unit-extensions");
if (!extension_dir)
return -ENOMEM;
/* If running under a different root filesystem, propagate the host's os-release. We make a
* copy rather than just bind mounting it, so that it can be updated on soft-reboot. */
if (setup_os_release_symlink) {
host_os_release_stage = strdup("/run/systemd/propagate/.os-release-stage");
if (!host_os_release_stage)
return -ENOMEM;
}
} else {
assert(params->runtime_scope == RUNTIME_SCOPE_USER);
if (asprintf(&extension_dir, "/run/user/" UID_FMT "/systemd/unit-extensions", geteuid()) < 0)
return -ENOMEM;
if (setup_os_release_symlink) {
if (asprintf(&host_os_release_stage,
"/run/user/" UID_FMT "/systemd/propagate/.os-release-stage",
geteuid()) < 0)
return -ENOMEM;
}
}
if (root_image) {
r = verity_settings_prepare(
&verity,
root_image,
context->root_hash, context->root_hash_size, context->root_hash_path,
context->root_hash_sig, context->root_hash_sig_size, context->root_hash_sig_path,
context->root_verity);
if (r < 0)
return r;
}
NamespaceParameters parameters = {
.runtime_scope = params->runtime_scope,
.root_directory = root_dir,
.root_image = root_image,
.root_image_options = context->root_image_options,
.root_image_policy = context->root_image_policy ?: &image_policy_service,
.read_write_paths = read_write_paths,
.read_only_paths = needs_sandboxing ? context->read_only_paths : NULL,
.inaccessible_paths = needs_sandboxing ? context->inaccessible_paths : NULL,
.exec_paths = needs_sandboxing ? context->exec_paths : NULL,
.no_exec_paths = needs_sandboxing ? context->no_exec_paths : NULL,
.empty_directories = empty_directories,
.symlinks = symlinks,
.bind_mounts = bind_mounts,
.n_bind_mounts = n_bind_mounts,
.temporary_filesystems = context->temporary_filesystems,
.n_temporary_filesystems = context->n_temporary_filesystems,
.mount_images = context->mount_images,
.n_mount_images = context->n_mount_images,
.mount_image_policy = context->mount_image_policy ?: &image_policy_service,
.tmp_dir = tmp_dir,
.var_tmp_dir = var_tmp_dir,
.creds_path = creds_path,
.log_namespace = context->log_namespace,
.mount_propagation_flag = context->mount_propagation_flag,
.verity = &verity,
.extension_images = context->extension_images,
.n_extension_images = context->n_extension_images,
.extension_image_policy = context->extension_image_policy ?: &image_policy_sysext,
.extension_directories = context->extension_directories,
.propagate_dir = propagate_dir,
.incoming_dir = incoming_dir,
.extension_dir = extension_dir,
.notify_socket = root_dir || root_image ? params->notify_socket : NULL,
.host_os_release_stage = host_os_release_stage,
/* If DynamicUser=no and RootDirectory= is set then lets pass a relaxed sandbox info,
* otherwise enforce it, don't ignore protected paths and fail if we are enable to apply the
* sandbox inside the mount namespace. */
.ignore_protect_paths = !needs_sandboxing && !context->dynamic_user && root_dir,
.protect_control_groups = needs_sandboxing && context->protect_control_groups,
.protect_kernel_tunables = needs_sandboxing && context->protect_kernel_tunables,
.protect_kernel_modules = needs_sandboxing && context->protect_kernel_modules,
.protect_kernel_logs = needs_sandboxing && context->protect_kernel_logs,
.protect_hostname = needs_sandboxing && context->protect_hostname,
.private_dev = needs_sandboxing && context->private_devices,
.private_network = needs_sandboxing && exec_needs_network_namespace(context),
.private_ipc = needs_sandboxing && exec_needs_ipc_namespace(context),
.mount_apivfs = needs_sandboxing && exec_context_get_effective_mount_apivfs(context),
/* If NNP is on, we can turn on MS_NOSUID, since it won't have any effect anymore. */
.mount_nosuid = needs_sandboxing && context->no_new_privileges && !mac_selinux_use(),
core: don't downgrade multi-state settings to boolean Protect{Home,System,Proc,Subset}= are not booleans, so make sure we use the intended value instead of just true/false. See: https://github.com/systemd/systemd/pull/29552 Follow-up to: 79d956d
2023-10-14 19:25:28 +02:00
.protect_home = needs_sandboxing ? context->protect_home : false,
.protect_system = needs_sandboxing ? context->protect_system : false,
.protect_proc = needs_sandboxing ? context->protect_proc : false,
.proc_subset = needs_sandboxing ? context->proc_subset : false,
core: move code from execute.c to exec-invoke.c No functional changes, only moving code that is only needed in exec_invoke, and adding new dependencies for seccomp/selinux/apparmor/pam in meson for the sd-executor binary.
2023-09-01 02:24:49 +01:00
};
r = setup_namespace(&parameters, error_path);
/* If we couldn't set up the namespace this is probably due to a missing capability. setup_namespace() reports
* that with a special, recognizable error ENOANO. In this case, silently proceed, but only if exclusively
* sandboxing options were used, i.e. nothing such as RootDirectory= or BindMount= that would result in a
* completely different execution environment. */
if (r == -ENOANO) {
if (insist_on_sandboxing(
context,
root_dir, root_image,
bind_mounts,
n_bind_mounts))
return log_exec_debug_errno(context,
params,
SYNTHETIC_ERRNO(EOPNOTSUPP),
"Failed to set up namespace, and refusing to continue since "
"the selected namespacing options alter mount environment non-trivially.\n"
"Bind mounts: %zu, temporary filesystems: %zu, root directory: %s, root image: %s, dynamic user: %s",
n_bind_mounts,
context->n_temporary_filesystems,
yes_no(root_dir),
yes_no(root_image),
yes_no(context->dynamic_user));
log_exec_debug(context, params, "Failed to set up namespace, assuming containerized execution and ignoring.");
return 0;
}
return r;
}
static int apply_working_directory(
const ExecContext *context,
const ExecParameters *params,
ExecRuntime *runtime,
const char *home,
int *exit_status) {
const char *d, *wd;
assert(context);
assert(exit_status);
if (context->working_directory_home) {
if (!home) {
*exit_status = EXIT_CHDIR;
return -ENXIO;
}
wd = home;
} else
wd = empty_to_root(context->working_directory);
if (params->flags & EXEC_APPLY_CHROOT)
d = wd;
else
d = prefix_roota((runtime ? runtime->ephemeral_copy : NULL) ?: context->root_directory, wd);
if (chdir(d) < 0 && !context->working_directory_missing_ok) {
*exit_status = EXIT_CHDIR;
return -errno;
}
return 0;
}
static int apply_root_directory(
const ExecContext *context,
const ExecParameters *params,
ExecRuntime *runtime,
const bool needs_mount_ns,
int *exit_status) {
assert(context);
assert(exit_status);
if (params->flags & EXEC_APPLY_CHROOT)
if (!needs_mount_ns && context->root_directory)
if (chroot((runtime ? runtime->ephemeral_copy : NULL) ?: context->root_directory) < 0) {
*exit_status = EXIT_CHROOT;
return -errno;
}
return 0;
}
static int setup_keyring(
const ExecContext *context,
const ExecParameters *p,
uid_t uid, gid_t gid) {
key_serial_t keyring;
int r = 0;
uid_t saved_uid;
gid_t saved_gid;
assert(context);
assert(p);
/* Let's set up a new per-service "session" kernel keyring for each system service. This has the benefit that
* each service runs with its own keyring shared among all processes of the service, but with no hook-up beyond
* that scope, and in particular no link to the per-UID keyring. If we don't do this the keyring will be
* automatically created on-demand and then linked to the per-UID keyring, by the kernel. The kernel's built-in
* on-demand behaviour is very appropriate for login users, but probably not so much for system services, where
* UIDs are not necessarily specific to a service but reused (at least in the case of UID 0). */
if (context->keyring_mode == EXEC_KEYRING_INHERIT)
return 0;
/* Acquiring a reference to the user keyring is nasty. We briefly change identity in order to get things set up
* properly by the kernel. If we don't do that then we can't create it atomically, and that sucks for parallel
* execution. This mimics what pam_keyinit does, too. Setting up session keyring, to be owned by the right user
* & group is just as nasty as acquiring a reference to the user keyring. */
saved_uid = getuid();
saved_gid = getgid();
if (gid_is_valid(gid) && gid != saved_gid) {
if (setregid(gid, -1) < 0)
return log_exec_error_errno(context,
p,
errno,
"Failed to change GID for user keyring: %m");
}
if (uid_is_valid(uid) && uid != saved_uid) {
if (setreuid(uid, -1) < 0) {
r = log_exec_error_errno(context,
p,
errno,
"Failed to change UID for user keyring: %m");
goto out;
}
}
keyring = keyctl(KEYCTL_JOIN_SESSION_KEYRING, 0, 0, 0, 0);
if (keyring == -1) {
if (errno == ENOSYS)
log_exec_debug_errno(context,
p,
errno,
"Kernel keyring not supported, ignoring.");
else if (ERRNO_IS_PRIVILEGE(errno))
log_exec_debug_errno(context,
p,
errno,
"Kernel keyring access prohibited, ignoring.");
else if (errno == EDQUOT)
log_exec_debug_errno(context,
p,
errno,
"Out of kernel keyrings to allocate, ignoring.");
else
r = log_exec_error_errno(context,
p,
errno,
"Setting up kernel keyring failed: %m");
goto out;
}
/* When requested link the user keyring into the session keyring. */
if (context->keyring_mode == EXEC_KEYRING_SHARED) {
if (keyctl(KEYCTL_LINK,
KEY_SPEC_USER_KEYRING,
KEY_SPEC_SESSION_KEYRING, 0, 0) < 0) {
r = log_exec_error_errno(context,
p,
errno,
"Failed to link user keyring into session keyring: %m");
goto out;
}
}
/* Restore uid/gid back */
if (uid_is_valid(uid) && uid != saved_uid) {
if (setreuid(saved_uid, -1) < 0) {
r = log_exec_error_errno(context,
p,
errno,
"Failed to change UID back for user keyring: %m");
goto out;
}
}
if (gid_is_valid(gid) && gid != saved_gid) {
if (setregid(saved_gid, -1) < 0)
return log_exec_error_errno(context,
p,
errno,
"Failed to change GID back for user keyring: %m");
}
/* Populate they keyring with the invocation ID by default, as original saved_uid. */
if (!sd_id128_is_null(p->invocation_id)) {
key_serial_t key;
key = add_key("user",
"invocation_id",
&p->invocation_id,
sizeof(p->invocation_id),
KEY_SPEC_SESSION_KEYRING);
if (key == -1)
log_exec_debug_errno(context,
p,
errno,
"Failed to add invocation ID to keyring, ignoring: %m");
else {
if (keyctl(KEYCTL_SETPERM, key,
KEY_POS_VIEW|KEY_POS_READ|KEY_POS_SEARCH|
KEY_USR_VIEW|KEY_USR_READ|KEY_USR_SEARCH, 0, 0) < 0)
r = log_exec_error_errno(context,
p,
errno,
"Failed to restrict invocation ID permission: %m");
}
}
out:
/* Revert back uid & gid for the last time, and exit */
/* no extra logging, as only the first already reported error matters */
if (getuid() != saved_uid)
(void) setreuid(saved_uid, -1);
if (getgid() != saved_gid)
(void) setregid(saved_gid, -1);
return r;
}
static void append_socket_pair(int *array, size_t *n, const int pair[static 2]) {
assert(array);
assert(n);
assert(pair);
if (pair[0] >= 0)
array[(*n)++] = pair[0];
if (pair[1] >= 0)
array[(*n)++] = pair[1];
}
static int close_remaining_fds(
const ExecParameters *params,
const ExecRuntime *runtime,
int socket_fd,
const int *fds, size_t n_fds) {
size_t n_dont_close = 0;
int dont_close[n_fds + 14];
assert(params);
if (params->stdin_fd >= 0)
dont_close[n_dont_close++] = params->stdin_fd;
if (params->stdout_fd >= 0)
dont_close[n_dont_close++] = params->stdout_fd;
if (params->stderr_fd >= 0)
dont_close[n_dont_close++] = params->stderr_fd;
if (socket_fd >= 0)
dont_close[n_dont_close++] = socket_fd;
if (n_fds > 0) {
memcpy(dont_close + n_dont_close, fds, sizeof(int) * n_fds);
n_dont_close += n_fds;
}
if (runtime)
append_socket_pair(dont_close, &n_dont_close, runtime->ephemeral_storage_socket);
if (runtime && runtime->shared) {
append_socket_pair(dont_close, &n_dont_close, runtime->shared->netns_storage_socket);
append_socket_pair(dont_close, &n_dont_close, runtime->shared->ipcns_storage_socket);
}
if (runtime && runtime->dynamic_creds) {
if (runtime->dynamic_creds->user)
append_socket_pair(dont_close, &n_dont_close, runtime->dynamic_creds->user->storage_socket);
if (runtime->dynamic_creds->group)
append_socket_pair(dont_close, &n_dont_close, runtime->dynamic_creds->group->storage_socket);
}
if (params->user_lookup_fd >= 0)
dont_close[n_dont_close++] = params->user_lookup_fd;
return close_all_fds(dont_close, n_dont_close);
}
static int send_user_lookup(
const char *unit_id,
int user_lookup_fd,
uid_t uid,
gid_t gid) {
assert(unit_id);
/* Send the resolved UID/GID to PID 1 after we learnt it. We send a single datagram, containing the UID/GID
* data as well as the unit name. Note that we suppress sending this if no user/group to resolve was
* specified. */
if (user_lookup_fd < 0)
return 0;
if (!uid_is_valid(uid) && !gid_is_valid(gid))
return 0;
if (writev(user_lookup_fd,
(struct iovec[]) {
IOVEC_MAKE(&uid, sizeof(uid)),
IOVEC_MAKE(&gid, sizeof(gid)),
IOVEC_MAKE_STRING(unit_id) }, 3) < 0)
return -errno;
return 0;
}
static int acquire_home(const ExecContext *c, uid_t uid, const char** home, char **buf) {
int r;
assert(c);
assert(home);
assert(buf);
/* If WorkingDirectory=~ is set, try to acquire a usable home directory. */
if (*home)
return 0;
if (!c->working_directory_home)
return 0;
r = get_home_dir(buf);
if (r < 0)
return r;
*home = *buf;
return 1;
}
static int compile_suggested_paths(const ExecContext *c, const ExecParameters *p, char ***ret) {
_cleanup_strv_free_ char ** list = NULL;
int r;
assert(c);
assert(p);
assert(ret);
assert(c->dynamic_user);
/* Compile a list of paths that it might make sense to read the owning UID from to use as initial candidate for
* dynamic UID allocation, in order to save us from doing costly recursive chown()s of the special
* directories. */
for (ExecDirectoryType t = 0; t < _EXEC_DIRECTORY_TYPE_MAX; t++) {
if (t == EXEC_DIRECTORY_CONFIGURATION)
continue;
if (!p->prefix[t])
continue;
for (size_t i = 0; i < c->directories[t].n_items; i++) {
char *e;
if (exec_directory_is_private(c, t))
e = path_join(p->prefix[t], "private", c->directories[t].items[i].path);
else
e = path_join(p->prefix[t], c->directories[t].items[i].path);
if (!e)
return -ENOMEM;
r = strv_consume(&list, e);
if (r < 0)
return r;
}
}
*ret = TAKE_PTR(list);
return 0;
}
static int exec_context_cpu_affinity_from_numa(const ExecContext *c, CPUSet *ret) {
_cleanup_(cpu_set_reset) CPUSet s = {};
int r;
assert(c);
assert(ret);
if (!c->numa_policy.nodes.set) {
log_debug("Can't derive CPU affinity mask from NUMA mask because NUMA mask is not set, ignoring");
return 0;
}
r = numa_to_cpu_set(&c->numa_policy, &s);
if (r < 0)
return r;
cpu_set_reset(ret);
return cpu_set_add_all(ret, &s);
}
static int add_shifted_fd(int *fds, size_t fds_size, size_t *n_fds, int fd, int *ret_fd) {
int r;
assert(fds);
assert(n_fds);
assert(*n_fds < fds_size);
assert(ret_fd);
if (fd < 0) {
*ret_fd = -EBADF;
return 0;
}
if (fd < 3 + (int) *n_fds) {
/* Let's move the fd up, so that it's outside of the fd range we will use to store
* the fds we pass to the process (or which are closed only during execve). */
r = fcntl(fd, F_DUPFD_CLOEXEC, 3 + (int) *n_fds);
if (r < 0)
return -errno;
close_and_replace(fd, r);
}
*ret_fd = fds[*n_fds] = fd;
(*n_fds) ++;
return 1;
}
static int connect_unix_harder(const ExecContext *c, const ExecParameters *p, const OpenFile *of, int ofd) {
union sockaddr_union addr = {
.un.sun_family = AF_UNIX,
};
socklen_t sa_len;
static const int socket_types[] = { SOCK_DGRAM, SOCK_STREAM, SOCK_SEQPACKET };
int r;
assert(c);
assert(p);
assert(of);
assert(ofd >= 0);
r = sockaddr_un_set_path(&addr.un, FORMAT_PROC_FD_PATH(ofd));
if (r < 0)
return log_exec_error_errno(c, p, r, "Failed to set sockaddr for %s: %m", of->path);
sa_len = r;
for (size_t i = 0; i < ELEMENTSOF(socket_types); i++) {
_cleanup_close_ int fd = -EBADF;
fd = socket(AF_UNIX, socket_types[i] | SOCK_CLOEXEC, 0);
if (fd < 0)
return log_exec_error_errno(c,
p,
errno,
"Failed to create socket for %s: %m",
of->path);
r = RET_NERRNO(connect(fd, &addr.sa, sa_len));
if (r == -EPROTOTYPE)
continue;
if (r < 0)
return log_exec_error_errno(c,
p,
r,
"Failed to connect socket for %s: %m",
of->path);
return TAKE_FD(fd);
}
return log_exec_error_errno(c,
p,
SYNTHETIC_ERRNO(EPROTOTYPE), "Failed to connect socket for \"%s\".",
of->path);
}
static int get_open_file_fd(const ExecContext *c, const ExecParameters *p, const OpenFile *of) {
struct stat st;
_cleanup_close_ int fd = -EBADF, ofd = -EBADF;
assert(c);
assert(p);
assert(of);
ofd = open(of->path, O_PATH | O_CLOEXEC);
if (ofd < 0)
return log_exec_error_errno(c, p, errno, "Could not open \"%s\": %m", of->path);
if (fstat(ofd, &st) < 0)
return log_exec_error_errno(c, p, errno, "Failed to stat %s: %m", of->path);
if (S_ISSOCK(st.st_mode)) {
fd = connect_unix_harder(c, p, of, ofd);
if (fd < 0)
return fd;
if (FLAGS_SET(of->flags, OPENFILE_READ_ONLY) && shutdown(fd, SHUT_WR) < 0)
return log_exec_error_errno(c, p, errno, "Failed to shutdown send for socket %s: %m",
of->path);
log_exec_debug(c, p, "socket %s opened (fd=%d)", of->path, fd);
} else {
int flags = FLAGS_SET(of->flags, OPENFILE_READ_ONLY) ? O_RDONLY : O_RDWR;
if (FLAGS_SET(of->flags, OPENFILE_APPEND))
flags |= O_APPEND;
else if (FLAGS_SET(of->flags, OPENFILE_TRUNCATE))
flags |= O_TRUNC;
fd = fd_reopen(ofd, flags | O_CLOEXEC);
if (fd < 0)
return log_exec_error_errno(c, p, fd, "Failed to open file %s: %m", of->path);
log_exec_debug(c, p, "file %s opened (fd=%d)", of->path, fd);
}
return TAKE_FD(fd);
}
static int collect_open_file_fds(
const ExecContext *c,
const ExecParameters *p,
int **fds,
char ***fdnames,
size_t *n_fds) {
int r;
assert(c);
assert(p);
assert(fds);
assert(fdnames);
assert(n_fds);
LIST_FOREACH(open_files, of, p->open_files) {
_cleanup_close_ int fd = -EBADF;
fd = get_open_file_fd(c, p, of);
if (fd < 0) {
if (FLAGS_SET(of->flags, OPENFILE_GRACEFUL)) {
log_exec_debug_errno(c, p, fd, "Failed to get OpenFile= file descriptor for %s, ignoring: %m", of->path);
continue;
}
return fd;
}
if (!GREEDY_REALLOC(*fds, *n_fds + 1))
return -ENOMEM;
r = strv_extend(fdnames, of->fdname);
if (r < 0)
return r;
(*fds)[*n_fds] = TAKE_FD(fd);
(*n_fds)++;
}
return 0;
}
static void log_command_line(
const ExecContext *context,
const ExecParameters *params,
const char *msg,
const char *executable,
char **argv) {
assert(context);
assert(params);
assert(msg);
assert(executable);
if (!DEBUG_LOGGING)
return;
_cleanup_free_ char *cmdline = quote_command_line(argv, SHELL_ESCAPE_EMPTY);
log_exec_struct(context, params, LOG_DEBUG,
"EXECUTABLE=%s", executable,
LOG_EXEC_MESSAGE(params, "%s: %s", msg, strnull(cmdline)),
LOG_EXEC_INVOCATION_ID(params));
}
static bool exec_context_need_unprivileged_private_users(
const ExecContext *context,
const ExecParameters *params) {
assert(context);
assert(params);
/* These options require PrivateUsers= when used in user units, as we need to be in a user namespace
* to have permission to enable them when not running as root. If we have effective CAP_SYS_ADMIN
* (system manager) then we have privileges and don't need this. */
if (params->runtime_scope != RUNTIME_SCOPE_USER)
return false;
return context->private_users ||
context->private_tmp ||
context->private_devices ||
context->private_network ||
context->network_namespace_path ||
context->private_ipc ||
context->ipc_namespace_path ||
context->private_mounts > 0 ||
context->mount_apivfs ||
context->n_bind_mounts > 0 ||
context->n_temporary_filesystems > 0 ||
context->root_directory ||
!strv_isempty(context->extension_directories) ||
context->protect_system != PROTECT_SYSTEM_NO ||
context->protect_home != PROTECT_HOME_NO ||
context->protect_kernel_tunables ||
context->protect_kernel_modules ||
context->protect_kernel_logs ||
context->protect_control_groups ||
context->protect_clock ||
context->protect_hostname ||
!strv_isempty(context->read_write_paths) ||
!strv_isempty(context->read_only_paths) ||
!strv_isempty(context->inaccessible_paths) ||
!strv_isempty(context->exec_paths) ||
!strv_isempty(context->no_exec_paths);
}
static bool exec_context_shall_confirm_spawn(const ExecContext *context) {
assert(context);
if (confirm_spawn_disabled())
return false;
/* For some reasons units remaining in the same process group
* as PID 1 fail to acquire the console even if it's not used
* by any process. So skip the confirmation question for them. */
return !context->same_pgrp;
}
static int exec_context_named_iofds(
const ExecContext *c,
const ExecParameters *p,
int named_iofds[static 3]) {
size_t targets;
const char* stdio_fdname[3];
size_t n_fds;
assert(c);
assert(p);
assert(named_iofds);
targets = (c->std_input == EXEC_INPUT_NAMED_FD) +
(c->std_output == EXEC_OUTPUT_NAMED_FD) +
(c->std_error == EXEC_OUTPUT_NAMED_FD);
for (size_t i = 0; i < 3; i++)
stdio_fdname[i] = exec_context_fdname(c, i);
n_fds = p->n_storage_fds + p->n_socket_fds;
for (size_t i = 0; i < n_fds && targets > 0; i++)
if (named_iofds[STDIN_FILENO] < 0 &&
c->std_input == EXEC_INPUT_NAMED_FD &&
stdio_fdname[STDIN_FILENO] &&
streq(p->fd_names[i], stdio_fdname[STDIN_FILENO])) {
named_iofds[STDIN_FILENO] = p->fds[i];
targets--;
} else if (named_iofds[STDOUT_FILENO] < 0 &&
c->std_output == EXEC_OUTPUT_NAMED_FD &&
stdio_fdname[STDOUT_FILENO] &&
streq(p->fd_names[i], stdio_fdname[STDOUT_FILENO])) {
named_iofds[STDOUT_FILENO] = p->fds[i];
targets--;
} else if (named_iofds[STDERR_FILENO] < 0 &&
c->std_error == EXEC_OUTPUT_NAMED_FD &&
stdio_fdname[STDERR_FILENO] &&
streq(p->fd_names[i], stdio_fdname[STDERR_FILENO])) {
named_iofds[STDERR_FILENO] = p->fds[i];
targets--;
}
return targets == 0 ? 0 : -ENOENT;
}
exec-invoke: don't double-close FDs on error When a late error occurs in sd-executor, the cleanup-on-close of the context structs happen, but at that time all FDs might have already been closed via close_all_fds(), so a double-close happens. This can be seen when DynamicUser is enabled, with a non-existing WorkingDirectory. Invalidate the FDs in the context structs if close_all_fds succeeds.
2023-10-27 16:33:49 +01:00
static void exec_shared_runtime_close(ExecSharedRuntime *shared) {
if (!shared)
return;
safe_close_pair(shared->netns_storage_socket);
safe_close_pair(shared->ipcns_storage_socket);
}
static void exec_runtime_close(ExecRuntime *rt) {
if (!rt)
return;
safe_close_pair(rt->ephemeral_storage_socket);
exec_shared_runtime_close(rt->shared);
dynamic_creds_close(rt->dynamic_creds);
}
static void exec_params_close(ExecParameters *p) {
if (!p)
return;
p->stdin_fd = safe_close(p->stdin_fd);
p->stdout_fd = safe_close(p->stdout_fd);
p->stderr_fd = safe_close(p->stderr_fd);
}
core: move code from execute.c to exec-invoke.c No functional changes, only moving code that is only needed in exec_invoke, and adding new dependencies for seccomp/selinux/apparmor/pam in meson for the sd-executor binary.
2023-09-01 02:24:49 +01:00
int exec_invoke(
const ExecCommand *command,
const ExecContext *context,
ExecParameters *params,
ExecRuntime *runtime,
const CGroupContext *cgroup_context,
int *exit_status) {
_cleanup_strv_free_ char **our_env = NULL, **pass_env = NULL, **joined_exec_search_path = NULL, **accum_env = NULL, **replaced_argv = NULL;
int r, ngids = 0, exec_fd;
_cleanup_free_ gid_t *supplementary_gids = NULL;
const char *username = NULL, *groupname = NULL;
_cleanup_free_ char *home_buffer = NULL, *memory_pressure_path = NULL;
const char *home = NULL, *shell = NULL;
char **final_argv = NULL;
dev_t journal_stream_dev = 0;
ino_t journal_stream_ino = 0;
bool userns_set_up = false;
bool needs_sandboxing, /* Do we need to set up full sandboxing? (i.e. all namespacing, all MAC stuff, caps, yadda yadda */
needs_setuid, /* Do we need to do the actual setresuid()/setresgid() calls? */
needs_mount_namespace, /* Do we need to set up a mount namespace for this kernel? */
needs_ambient_hack; /* Do we need to apply the ambient capabilities hack? */
core: allow using seccomp without no_new_privs when unprivileged Until now, using any form of seccomp while being unprivileged (User=) resulted in systemd enabling no_new_privs. There's no need for doing this because: * We trust the filters we apply * If User= is set and a process wants to apply a new seccomp filter, it will need to set no_new_privs itself An example of application that might want seccomp + !no_new_privs is a program that wants to run as an unprivileged user but uses file capabilities to start a web server on a privileged port while benefitting from a restrictive seccomp profile. We now keep the privileges needed to do seccomp before calling enforce_user() and drop them after the seccomp filters are applied. If the syscall filter doesn't allow the needed syscalls to drop the privileges, we keep the previous behavior by enabling no_new_privs.
2023-11-07 11:06:56 +01:00
bool keep_seccomp_privileges = false;
core: move code from execute.c to exec-invoke.c No functional changes, only moving code that is only needed in exec_invoke, and adding new dependencies for seccomp/selinux/apparmor/pam in meson for the sd-executor binary.
2023-09-01 02:24:49 +01:00
#if HAVE_SELINUX
_cleanup_free_ char *mac_selinux_context_net = NULL;
bool use_selinux = false;
#endif
#if ENABLE_SMACK
bool use_smack = false;
#endif
#if HAVE_APPARMOR
bool use_apparmor = false;
core: allow using seccomp without no_new_privs when unprivileged Until now, using any form of seccomp while being unprivileged (User=) resulted in systemd enabling no_new_privs. There's no need for doing this because: * We trust the filters we apply * If User= is set and a process wants to apply a new seccomp filter, it will need to set no_new_privs itself An example of application that might want seccomp + !no_new_privs is a program that wants to run as an unprivileged user but uses file capabilities to start a web server on a privileged port while benefitting from a restrictive seccomp profile. We now keep the privileges needed to do seccomp before calling enforce_user() and drop them after the seccomp filters are applied. If the syscall filter doesn't allow the needed syscalls to drop the privileges, we keep the previous behavior by enabling no_new_privs.
2023-11-07 11:06:56 +01:00
#endif
#if HAVE_SECCOMP
uint64_t saved_bset = 0;
core: move code from execute.c to exec-invoke.c No functional changes, only moving code that is only needed in exec_invoke, and adding new dependencies for seccomp/selinux/apparmor/pam in meson for the sd-executor binary.
2023-09-01 02:24:49 +01:00
#endif
uid_t saved_uid = getuid();
gid_t saved_gid = getgid();
uid_t uid = UID_INVALID;
gid_t gid = GID_INVALID;
size_t n_fds, /* fds to pass to the child */
n_keep_fds; /* total number of fds not to close */
int secure_bits;
_cleanup_free_ gid_t *gids_after_pam = NULL;
int ngids_after_pam = 0;
_cleanup_free_ int *fds = NULL;
_cleanup_strv_free_ char **fdnames = NULL;
fd-uitl: rename PIPE_EBADF → EBADF_PAIR, and add EBADF_TRIPLET We use it for more than just pipe() arrays. For example also for socketpair(). Hence let's give it a generic name. Also add EBADF_TRIPLET to mirror this for things like stdin/stdout/stderr arrays, which we use a bunch of times.
2023-10-26 18:45:33 +02:00
int socket_fd = -EBADF, named_iofds[3] = EBADF_TRIPLET, *params_fds = NULL;
core: move code from execute.c to exec-invoke.c No functional changes, only moving code that is only needed in exec_invoke, and adding new dependencies for seccomp/selinux/apparmor/pam in meson for the sd-executor binary.
2023-09-01 02:24:49 +01:00
size_t n_storage_fds = 0, n_socket_fds = 0;
assert(command);
assert(context);
assert(params);
assert(exit_status);
/* Explicitly test for CVE-2021-4034 inspired invocations */
executor: return instead of assert on invalid command line arguments Before the split, it made sense to assert, as checks were on setup. But now these come from deserialization, and the fuzzer hits the asserts, so simply return an error instead.
2023-10-19 20:53:10 +01:00
if (!command->path || strv_isempty(command->argv)) {
*exit_status = EXIT_EXEC;
return log_exec_error_errno(
context,
params,
SYNTHETIC_ERRNO(EINVAL),
"Invalid command line arguments.");
}
core: move code from execute.c to exec-invoke.c No functional changes, only moving code that is only needed in exec_invoke, and adding new dependencies for seccomp/selinux/apparmor/pam in meson for the sd-executor binary.
2023-09-01 02:24:49 +01:00
LOG_CONTEXT_PUSH_EXEC(context, params);
if (context->std_input == EXEC_INPUT_SOCKET ||
context->std_output == EXEC_OUTPUT_SOCKET ||
context->std_error == EXEC_OUTPUT_SOCKET) {
if (params->n_socket_fds > 1)
return log_exec_error_errno(context, params, SYNTHETIC_ERRNO(EINVAL), "Got more than one socket.");
if (params->n_socket_fds == 0)
return log_exec_error_errno(context, params, SYNTHETIC_ERRNO(EINVAL), "Got no socket.");
socket_fd = params->fds[0];
} else {
params_fds = params->fds;
n_socket_fds = params->n_socket_fds;
n_storage_fds = params->n_storage_fds;
}
n_fds = n_socket_fds + n_storage_fds;
r = exec_context_named_iofds(context, params, named_iofds);
if (r < 0)
return log_exec_error_errno(context, params, r, "Failed to load a named file descriptor: %m");
rename_process_from_path(command->path);
/* We reset exactly these signals, since they are the only ones we set to SIG_IGN in the main
* daemon. All others we leave untouched because we set them to SIG_DFL or a valid handler initially,
* both of which will be demoted to SIG_DFL. */
(void) default_signals(SIGNALS_CRASH_HANDLER,
SIGNALS_IGNORE);
if (context->ignore_sigpipe)
(void) ignore_signals(SIGPIPE);
r = reset_signal_mask();
if (r < 0) {
*exit_status = EXIT_SIGNAL_MASK;
return log_exec_error_errno(context, params, r, "Failed to set process signal mask: %m");
}
if (params->idle_pipe)
do_idle_pipe_dance(params->idle_pipe);
/* Close fds we don't need very early to make sure we don't block init reexecution because it cannot bind its
* sockets. Among the fds we close are the logging fds, and we want to keep them closed, so that we don't have
* any fds open we don't really want open during the transition. In order to make logging work, we switch the
* log subsystem into open_when_needed mode, so that it reopens the logs on every single log call. */
log_forget_fds();
log_set_open_when_needed(true);
log_settle_target();
if (context->log_level_max >= 0)
log_set_max_level(context->log_level_max);
/* In case anything used libc syslog(), close this here, too */
closelog();
fds = newdup(int, params_fds, n_fds);
if (!fds) {
*exit_status = EXIT_MEMORY;
return log_oom();
}
fdnames = strv_copy((char**) params->fd_names);
if (!fdnames) {
*exit_status = EXIT_MEMORY;
return log_oom();
}
r = collect_open_file_fds(context, params, &fds, &fdnames, &n_fds);
if (r < 0) {
*exit_status = EXIT_FDS;
return log_exec_error_errno(context, params, r, "Failed to get OpenFile= file descriptors: %m");
}
int keep_fds[n_fds + 3];
memcpy_safe(keep_fds, fds, n_fds * sizeof(int));
n_keep_fds = n_fds;
r = add_shifted_fd(keep_fds, ELEMENTSOF(keep_fds), &n_keep_fds, params->exec_fd, &exec_fd);
if (r < 0) {
*exit_status = EXIT_FDS;
return log_exec_error_errno(context, params, r, "Failed to shift fd and set FD_CLOEXEC: %m");
}
#if HAVE_LIBBPF
if (params->bpf_outer_map_fd >= 0) {
r = add_shifted_fd(keep_fds, ELEMENTSOF(keep_fds), &n_keep_fds, params->bpf_outer_map_fd, (int *)&params->bpf_outer_map_fd);
if (r < 0) {
*exit_status = EXIT_FDS;
return log_exec_error_errno(context, params, r, "Failed to shift fd and set FD_CLOEXEC: %m");
}
}
#endif
r = close_remaining_fds(params, runtime, socket_fd, keep_fds, n_keep_fds);
if (r < 0) {
*exit_status = EXIT_FDS;
return log_exec_error_errno(context, params, r, "Failed to close unwanted file descriptors: %m");
}
if (!context->same_pgrp &&
setsid() < 0) {
*exit_status = EXIT_SETSID;
return log_exec_error_errno(context, params, errno, "Failed to create new process session: %m");
}
exec_context_tty_reset(context, params);
if (params->shall_confirm_spawn && exec_context_shall_confirm_spawn(context)) {
_cleanup_free_ char *cmdline = NULL;
cmdline = quote_command_line(command->argv, SHELL_ESCAPE_EMPTY);
if (!cmdline) {
*exit_status = EXIT_MEMORY;
return log_oom();
}
r = ask_for_confirmation(context, params, cmdline);
if (r != CONFIRM_EXECUTE) {
if (r == CONFIRM_PRETEND_SUCCESS) {
*exit_status = EXIT_SUCCESS;
return 0;
}
*exit_status = EXIT_CONFIRM;
return log_exec_error_errno(context, params, SYNTHETIC_ERRNO(ECANCELED),
"Execution cancelled by the user");
}
}
/* We are about to invoke NSS and PAM modules. Let's tell them what we are doing here, maybe they care. This is
* used by nss-resolve to disable itself when we are about to start systemd-resolved, to avoid deadlocks. Note
* that these env vars do not survive the execve(), which means they really only apply to the PAM and NSS
* invocations themselves. Also note that while we'll only invoke NSS modules involved in user management they
* might internally call into other NSS modules that are involved in hostname resolution, we never know. */
if (setenv("SYSTEMD_ACTIVATION_UNIT", params->unit_id, true) != 0 ||
setenv("SYSTEMD_ACTIVATION_SCOPE", runtime_scope_to_string(params->runtime_scope), true) != 0) {
*exit_status = EXIT_MEMORY;
return log_exec_error_errno(context, params, errno, "Failed to update environment: %m");
}
if (context->dynamic_user && runtime && runtime->dynamic_creds) {
_cleanup_strv_free_ char **suggested_paths = NULL;
/* On top of that, make sure we bypass our own NSS module nss-systemd comprehensively for any NSS
* checks, if DynamicUser=1 is used, as we shouldn't create a feedback loop with ourselves here. */
if (putenv((char*) "SYSTEMD_NSS_DYNAMIC_BYPASS=1") != 0) {
*exit_status = EXIT_USER;
return log_exec_error_errno(context, params, errno, "Failed to update environment: %m");
}
r = compile_suggested_paths(context, params, &suggested_paths);
if (r < 0) {
*exit_status = EXIT_MEMORY;
return log_oom();
}
r = dynamic_creds_realize(runtime->dynamic_creds, suggested_paths, &uid, &gid);
if (r < 0) {
*exit_status = EXIT_USER;
if (r == -EILSEQ)
return log_exec_error_errno(context, params, SYNTHETIC_ERRNO(EOPNOTSUPP),
"Failed to update dynamic user credentials: User or group with specified name already exists.");
return log_exec_error_errno(context, params, r, "Failed to update dynamic user credentials: %m");
}
if (!uid_is_valid(uid)) {
*exit_status = EXIT_USER;
return log_exec_error_errno(context, params, SYNTHETIC_ERRNO(ESRCH), "UID validation failed for \""UID_FMT"\"", uid);
}
if (!gid_is_valid(gid)) {
*exit_status = EXIT_USER;
return log_exec_error_errno(context, params, SYNTHETIC_ERRNO(ESRCH), "GID validation failed for \""GID_FMT"\"", gid);
}
if (runtime->dynamic_creds->user)
username = runtime->dynamic_creds->user->name;
} else {
if (context->user) {
r = get_fixed_user(context->user, &username, &uid, &gid, &home, &shell);
if (r < 0) {
*exit_status = EXIT_USER;
return log_exec_error_errno(context, params, r, "Failed to determine user credentials: %m");
}
}
if (context->group) {
r = get_fixed_group(context->group, &groupname, &gid);
if (r < 0) {
*exit_status = EXIT_GROUP;
return log_exec_error_errno(context, params, r, "Failed to determine group credentials: %m");
}
}
}
/* Initialize user supplementary groups and get SupplementaryGroups= ones */
r = get_supplementary_groups(context, username, groupname, gid,
&supplementary_gids, &ngids);
if (r < 0) {
*exit_status = EXIT_GROUP;
return log_exec_error_errno(context, params, r, "Failed to determine supplementary groups: %m");
}
r = send_user_lookup(params->unit_id, params->user_lookup_fd, uid, gid);
if (r < 0) {
*exit_status = EXIT_USER;
return log_exec_error_errno(context, params, r, "Failed to send user credentials to PID1: %m");
}
params->user_lookup_fd = safe_close(params->user_lookup_fd);
r = acquire_home(context, uid, &home, &home_buffer);
if (r < 0) {
*exit_status = EXIT_CHDIR;
return log_exec_error_errno(context, params, r, "Failed to determine $HOME for user: %m");
}
/* If a socket is connected to STDIN/STDOUT/STDERR, we must drop O_NONBLOCK */
if (socket_fd >= 0)
(void) fd_nonblock(socket_fd, false);
/* Journald will try to look-up our cgroup in order to populate _SYSTEMD_CGROUP and _SYSTEMD_UNIT fields.
* Hence we need to migrate to the target cgroup from init.scope before connecting to journald */
if (params->cgroup_path) {
_cleanup_free_ char *p = NULL;
r = exec_params_get_cgroup_path(params, cgroup_context, &p);
if (r < 0) {
*exit_status = EXIT_CGROUP;
return log_exec_error_errno(context, params, r, "Failed to acquire cgroup path: %m");
}
r = cg_attach_everywhere(params->cgroup_supported, p, 0, NULL, NULL);
if (r == -EUCLEAN) {
*exit_status = EXIT_CGROUP;
return log_exec_error_errno(context, params, r, "Failed to attach process to cgroup %s "
"because the cgroup or one of its parents or "
"siblings is in the threaded mode: %m", p);
}
if (r < 0) {
*exit_status = EXIT_CGROUP;
return log_exec_error_errno(context, params, r, "Failed to attach to cgroup %s: %m", p);
}
}
if (context->network_namespace_path && runtime && runtime->shared && runtime->shared->netns_storage_socket[0] >= 0) {
r = open_shareable_ns_path(runtime->shared->netns_storage_socket, context->network_namespace_path, CLONE_NEWNET);
if (r < 0) {
*exit_status = EXIT_NETWORK;
return log_exec_error_errno(context, params, r, "Failed to open network namespace path %s: %m", context->network_namespace_path);
}
}
if (context->ipc_namespace_path && runtime && runtime->shared && runtime->shared->ipcns_storage_socket[0] >= 0) {
r = open_shareable_ns_path(runtime->shared->ipcns_storage_socket, context->ipc_namespace_path, CLONE_NEWIPC);
if (r < 0) {
*exit_status = EXIT_NAMESPACE;
return log_exec_error_errno(context, params, r, "Failed to open IPC namespace path %s: %m", context->ipc_namespace_path);
}
}
r = setup_input(context, params, socket_fd, named_iofds);
if (r < 0) {
*exit_status = EXIT_STDIN;
return log_exec_error_errno(context, params, r, "Failed to set up standard input: %m");
}
r = setup_output(context, params, STDOUT_FILENO, socket_fd, named_iofds, basename(command->path), uid, gid, &journal_stream_dev, &journal_stream_ino);
if (r < 0) {
*exit_status = EXIT_STDOUT;
return log_exec_error_errno(context, params, r, "Failed to set up standard output: %m");
}
r = setup_output(context, params, STDERR_FILENO, socket_fd, named_iofds, basename(command->path), uid, gid, &journal_stream_dev, &journal_stream_ino);
if (r < 0) {
*exit_status = EXIT_STDERR;
return log_exec_error_errno(context, params, r, "Failed to set up standard error output: %m");
}
if (context->oom_score_adjust_set) {
/* When we can't make this change due to EPERM, then let's silently skip over it. User
* namespaces prohibit write access to this file, and we shouldn't trip up over that. */
r = set_oom_score_adjust(context->oom_score_adjust);
if (ERRNO_IS_NEG_PRIVILEGE(r))
log_exec_debug_errno(context, params, r,
"Failed to adjust OOM setting, assuming containerized execution, ignoring: %m");
else if (r < 0) {
*exit_status = EXIT_OOM_ADJUST;
return log_exec_error_errno(context, params, r, "Failed to adjust OOM setting: %m");
}
}
if (context->coredump_filter_set) {
r = set_coredump_filter(context->coredump_filter);
if (ERRNO_IS_NEG_PRIVILEGE(r))
log_exec_debug_errno(context, params, r, "Failed to adjust coredump_filter, ignoring: %m");
else if (r < 0) {
*exit_status = EXIT_LIMITS;
return log_exec_error_errno(context, params, r, "Failed to adjust coredump_filter: %m");
}
}
if (context->nice_set) {
r = setpriority_closest(context->nice);
if (r < 0) {
*exit_status = EXIT_NICE;
return log_exec_error_errno(context, params, r, "Failed to set up process scheduling priority (nice level): %m");
}
}
if (context->cpu_sched_set) {
struct sched_param param = {
.sched_priority = context->cpu_sched_priority,
};
r = sched_setscheduler(0,
context->cpu_sched_policy |
(context->cpu_sched_reset_on_fork ?
SCHED_RESET_ON_FORK : 0),
&param);
if (r < 0) {
*exit_status = EXIT_SETSCHEDULER;
return log_exec_error_errno(context, params, errno, "Failed to set up CPU scheduling: %m");
}
}
if (context->cpu_affinity_from_numa || context->cpu_set.set) {
_cleanup_(cpu_set_reset) CPUSet converted_cpu_set = {};
const CPUSet *cpu_set;
if (context->cpu_affinity_from_numa) {
r = exec_context_cpu_affinity_from_numa(context, &converted_cpu_set);
if (r < 0) {
*exit_status = EXIT_CPUAFFINITY;
return log_exec_error_errno(context, params, r, "Failed to derive CPU affinity mask from NUMA mask: %m");
}
cpu_set = &converted_cpu_set;
} else
cpu_set = &context->cpu_set;
if (sched_setaffinity(0, cpu_set->allocated, cpu_set->set) < 0) {
*exit_status = EXIT_CPUAFFINITY;
return log_exec_error_errno(context, params, errno, "Failed to set up CPU affinity: %m");
}
}
if (mpol_is_valid(numa_policy_get_type(&context->numa_policy))) {
r = apply_numa_policy(&context->numa_policy);
if (ERRNO_IS_NEG_NOT_SUPPORTED(r))
log_exec_debug_errno(context, params, r, "NUMA support not available, ignoring.");
else if (r < 0) {
*exit_status = EXIT_NUMA_POLICY;
return log_exec_error_errno(context, params, r, "Failed to set NUMA memory policy: %m");
}
}
if (context->ioprio_set)
if (ioprio_set(IOPRIO_WHO_PROCESS, 0, context->ioprio) < 0) {
*exit_status = EXIT_IOPRIO;
return log_exec_error_errno(context, params, errno, "Failed to set up IO scheduling priority: %m");
}
if (context->timer_slack_nsec != NSEC_INFINITY)
if (prctl(PR_SET_TIMERSLACK, context->timer_slack_nsec) < 0) {
*exit_status = EXIT_TIMERSLACK;
return log_exec_error_errno(context, params, errno, "Failed to set up timer slack: %m");
}
if (context->personality != PERSONALITY_INVALID) {
r = safe_personality(context->personality);
if (r < 0) {
*exit_status = EXIT_PERSONALITY;
return log_exec_error_errno(context, params, r, "Failed to set up execution domain (personality): %m");
}
}
if (context->utmp_id) {
const char *line = context->tty_path ?
(path_startswith(context->tty_path, "/dev/") ?: context->tty_path) :
NULL;
utmp_put_init_process(context->utmp_id, getpid_cached(), getsid(0),
line,
context->utmp_mode == EXEC_UTMP_INIT ? INIT_PROCESS :
context->utmp_mode == EXEC_UTMP_LOGIN ? LOGIN_PROCESS :
USER_PROCESS,
username);
}
if (uid_is_valid(uid)) {
r = chown_terminal(STDIN_FILENO, uid);
if (r < 0) {
*exit_status = EXIT_STDIN;
return log_exec_error_errno(context, params, r, "Failed to change ownership of terminal: %m");
}
}
if (params->cgroup_path) {
/* If delegation is enabled we'll pass ownership of the cgroup to the user of the new process. On cgroup v1
* this is only about systemd's own hierarchy, i.e. not the controller hierarchies, simply because that's not
* safe. On cgroup v2 there's only one hierarchy anyway, and delegation is safe there, hence in that case only
* touch a single hierarchy too. */
if (params->flags & EXEC_CGROUP_DELEGATE) {
_cleanup_free_ char *p = NULL;
r = cg_set_access(SYSTEMD_CGROUP_CONTROLLER, params->cgroup_path, uid, gid);
if (r < 0) {
*exit_status = EXIT_CGROUP;
return log_exec_error_errno(context, params, r, "Failed to adjust control group access: %m");
}
r = exec_params_get_cgroup_path(params, cgroup_context, &p);
if (r < 0) {
*exit_status = EXIT_CGROUP;
return log_exec_error_errno(context, params, r, "Failed to acquire cgroup path: %m");
}
if (r > 0) {
r = cg_set_access_recursive(SYSTEMD_CGROUP_CONTROLLER, p, uid, gid);
if (r < 0) {
*exit_status = EXIT_CGROUP;
return log_exec_error_errno(context, params, r, "Failed to adjust control subgroup access: %m");
}
}
}
if (cgroup_context && cg_unified() > 0 && is_pressure_supported() > 0) {
if (cgroup_context_want_memory_pressure(cgroup_context)) {
r = cg_get_path("memory", params->cgroup_path, "memory.pressure", &memory_pressure_path);
if (r < 0) {
*exit_status = EXIT_MEMORY;
return log_oom();
}
r = chmod_and_chown(memory_pressure_path, 0644, uid, gid);
if (r < 0) {
log_exec_full_errno(context, params, r == -ENOENT || ERRNO_IS_PRIVILEGE(r) ? LOG_DEBUG : LOG_WARNING, r,
"Failed to adjust ownership of '%s', ignoring: %m", memory_pressure_path);
memory_pressure_path = mfree(memory_pressure_path);
}
} else if (cgroup_context->memory_pressure_watch == CGROUP_PRESSURE_WATCH_OFF) {
memory_pressure_path = strdup("/dev/null"); /* /dev/null is explicit indicator for turning of memory pressure watch */
if (!memory_pressure_path) {
*exit_status = EXIT_MEMORY;
return log_oom();
}
}
}
}
needs_mount_namespace = exec_needs_mount_namespace(context, params, runtime);
for (ExecDirectoryType dt = 0; dt < _EXEC_DIRECTORY_TYPE_MAX; dt++) {
r = setup_exec_directory(context, params, uid, gid, dt, needs_mount_namespace, exit_status);
if (r < 0)
return log_exec_error_errno(context, params, r, "Failed to set up special execution directory in %s: %m", params->prefix[dt]);
}
if (FLAGS_SET(params->flags, EXEC_WRITE_CREDENTIALS)) {
r = exec_setup_credentials(context, params, params->unit_id, uid, gid);
if (r < 0) {
*exit_status = EXIT_CREDENTIALS;
return log_exec_error_errno(context, params, r, "Failed to set up credentials: %m");
}
}
r = build_environment(
context,
params,
cgroup_context,
n_fds,
fdnames,
home,
username,
shell,
journal_stream_dev,
journal_stream_ino,
memory_pressure_path,
&our_env);
if (r < 0) {
*exit_status = EXIT_MEMORY;
return log_oom();
}
r = build_pass_environment(context, &pass_env);
if (r < 0) {
*exit_status = EXIT_MEMORY;
return log_oom();
}
/* The $PATH variable is set to the default path in params->environment. However, this is overridden
* if user-specified fields have $PATH set. The intention is to also override $PATH if the unit does
* not specify PATH but the unit has ExecSearchPath. */
if (!strv_isempty(context->exec_search_path)) {
_cleanup_free_ char *joined = NULL;
joined = strv_join(context->exec_search_path, ":");
if (!joined) {
*exit_status = EXIT_MEMORY;
return log_oom();
}
r = strv_env_assign(&joined_exec_search_path, "PATH", joined);
if (r < 0) {
*exit_status = EXIT_MEMORY;
return log_oom();
}
}
accum_env = strv_env_merge(params->environment,
our_env,
joined_exec_search_path,
pass_env,
context->environment,
params->files_env);
if (!accum_env) {
*exit_status = EXIT_MEMORY;
return log_oom();
}
accum_env = strv_env_clean(accum_env);
(void) umask(context->umask);
r = setup_keyring(context, params, uid, gid);
if (r < 0) {
*exit_status = EXIT_KEYRING;
return log_exec_error_errno(context, params, r, "Failed to set up kernel keyring: %m");
}
/* We need sandboxing if the caller asked us to apply it and the command isn't explicitly excepted
* from it. */
needs_sandboxing = (params->flags & EXEC_APPLY_SANDBOXING) && !(command->flags & EXEC_COMMAND_FULLY_PRIVILEGED);
/* We need the ambient capability hack, if the caller asked us to apply it and the command is marked
* for it, and the kernel doesn't actually support ambient caps. */
needs_ambient_hack = (params->flags & EXEC_APPLY_SANDBOXING) && (command->flags & EXEC_COMMAND_AMBIENT_MAGIC) && !ambient_capabilities_supported();
/* We need setresuid() if the caller asked us to apply sandboxing and the command isn't explicitly
* excepted from either whole sandboxing or just setresuid() itself, and the ambient hack is not
* desired. */
if (needs_ambient_hack)
needs_setuid = false;
else
needs_setuid = (params->flags & EXEC_APPLY_SANDBOXING) && !(command->flags & (EXEC_COMMAND_FULLY_PRIVILEGED|EXEC_COMMAND_NO_SETUID));
uint64_t capability_ambient_set = context->capability_ambient_set;
if (needs_sandboxing) {
/* MAC enablement checks need to be done before a new mount ns is created, as they rely on
* /sys being present. The actual MAC context application will happen later, as late as
* possible, to avoid impacting our own code paths. */
#if HAVE_SELINUX
use_selinux = mac_selinux_use();
#endif
#if ENABLE_SMACK
use_smack = mac_smack_use();
#endif
#if HAVE_APPARMOR
use_apparmor = mac_apparmor_use();
#endif
}
if (needs_sandboxing) {
int which_failed;
/* Let's set the resource limits before we call into PAM, so that pam_limits wins over what
* is set here. (See below.) */
r = setrlimit_closest_all((const struct rlimit* const *) context->rlimit, &which_failed);
if (r < 0) {
*exit_status = EXIT_LIMITS;
return log_exec_error_errno(context, params, r, "Failed to adjust resource limit RLIMIT_%s: %m", rlimit_to_string(which_failed));
}
}
if (needs_setuid && context->pam_name && username) {
core: fix a couple of typos
2023-10-31 17:33:29 +01:00
/* Let's call into PAM after we set up our own idea of resource limits so that pam_limits
core: move code from execute.c to exec-invoke.c No functional changes, only moving code that is only needed in exec_invoke, and adding new dependencies for seccomp/selinux/apparmor/pam in meson for the sd-executor binary.
2023-09-01 02:24:49 +01:00
* wins here. (See above.) */
/* All fds passed in the fds array will be closed in the pam child process. */
r = setup_pam(context->pam_name, username, uid, gid, context->tty_path, &accum_env, fds, n_fds);
if (r < 0) {
*exit_status = EXIT_PAM;
return log_exec_error_errno(context, params, r, "Failed to set up PAM session: %m");
}
if (ambient_capabilities_supported()) {
uint64_t ambient_after_pam;
/* PAM modules might have set some ambient caps. Query them here and merge them into
* the caps we want to set in the end, so that we don't end up unsetting them. */
r = capability_get_ambient(&ambient_after_pam);
if (r < 0) {
*exit_status = EXIT_CAPABILITIES;
return log_exec_error_errno(context, params, r, "Failed to query ambient caps: %m");
}
capability_ambient_set |= ambient_after_pam;
}
ngids_after_pam = getgroups_alloc(&gids_after_pam);
if (ngids_after_pam < 0) {
core/exec-invoke: use correct exit status These calls can fail not only due to OOM.
2023-10-18 21:22:19 +08:00
*exit_status = EXIT_GROUP;
core: move code from execute.c to exec-invoke.c No functional changes, only moving code that is only needed in exec_invoke, and adding new dependencies for seccomp/selinux/apparmor/pam in meson for the sd-executor binary.
2023-09-01 02:24:49 +01:00
return log_exec_error_errno(context, params, ngids_after_pam, "Failed to obtain groups after setting up PAM: %m");
}
}
if (needs_sandboxing && exec_context_need_unprivileged_private_users(context, params)) {
/* If we're unprivileged, set up the user namespace first to enable use of the other namespaces.
* Users with CAP_SYS_ADMIN can set up user namespaces last because they will be able to
core: fix a couple of typos
2023-10-31 17:33:29 +01:00
* set up all of the other namespaces (i.e. network, mount, UTS) without a user namespace. */
core: move code from execute.c to exec-invoke.c No functional changes, only moving code that is only needed in exec_invoke, and adding new dependencies for seccomp/selinux/apparmor/pam in meson for the sd-executor binary.
2023-09-01 02:24:49 +01:00
r = setup_private_users(saved_uid, saved_gid, uid, gid);
/* If it was requested explicitly and we can't set it up, fail early. Otherwise, continue and let
* the actual requested operations fail (or silently continue). */
if (r < 0 && context->private_users) {
*exit_status = EXIT_USER;
return log_exec_error_errno(context, params, r, "Failed to set up user namespacing for unprivileged user: %m");
}
if (r < 0)
log_exec_info_errno(context, params, r, "Failed to set up user namespacing for unprivileged user, ignoring: %m");
else
userns_set_up = true;
}
if (exec_needs_network_namespace(context) && runtime && runtime->shared && runtime->shared->netns_storage_socket[0] >= 0) {
/* Try to enable network namespacing if network namespacing is available and we have
* CAP_NET_ADMIN. We need CAP_NET_ADMIN to be able to configure the loopback device in the
* new network namespace. And if we don't have that, then we could only create a network
* namespace without the ability to set up "lo". Hence gracefully skip things then. */
if (ns_type_supported(NAMESPACE_NET) && have_effective_cap(CAP_NET_ADMIN) > 0) {
r = setup_shareable_ns(runtime->shared->netns_storage_socket, CLONE_NEWNET);
if (ERRNO_IS_NEG_PRIVILEGE(r))
log_exec_notice_errno(context, params, r,
"PrivateNetwork=yes is configured, but network namespace setup not permitted, proceeding without: %m");
else if (r < 0) {
*exit_status = EXIT_NETWORK;
return log_exec_error_errno(context, params, r, "Failed to set up network namespacing: %m");
}
} else if (context->network_namespace_path) {
*exit_status = EXIT_NETWORK;
return log_exec_error_errno(context, params, SYNTHETIC_ERRNO(EOPNOTSUPP),
"NetworkNamespacePath= is not supported, refusing.");
} else
log_exec_notice(context, params, "PrivateNetwork=yes is configured, but the kernel does not support or we lack privileges for network namespace, proceeding without.");
}
if (exec_needs_ipc_namespace(context) && runtime && runtime->shared && runtime->shared->ipcns_storage_socket[0] >= 0) {
if (ns_type_supported(NAMESPACE_IPC)) {
r = setup_shareable_ns(runtime->shared->ipcns_storage_socket, CLONE_NEWIPC);
if (r == -EPERM)
log_exec_warning_errno(context, params, r,
"PrivateIPC=yes is configured, but IPC namespace setup failed, ignoring: %m");
else if (r < 0) {
*exit_status = EXIT_NAMESPACE;
return log_exec_error_errno(context, params, r, "Failed to set up IPC namespacing: %m");
}
} else if (context->ipc_namespace_path) {
*exit_status = EXIT_NAMESPACE;
return log_exec_error_errno(context, params, SYNTHETIC_ERRNO(EOPNOTSUPP),
"IPCNamespacePath= is not supported, refusing.");
} else
log_exec_warning(context, params, "PrivateIPC=yes is configured, but the kernel does not support IPC namespaces, ignoring.");
}
if (needs_mount_namespace) {
_cleanup_free_ char *error_path = NULL;
r = apply_mount_namespace(command->flags, context, params, runtime, memory_pressure_path, &error_path);
if (r < 0) {
*exit_status = EXIT_NAMESPACE;
return log_exec_error_errno(context, params, r, "Failed to set up mount namespacing%s%s: %m",
error_path ? ": " : "", strempty(error_path));
}
}
if (needs_sandboxing) {
r = apply_protect_hostname(context, params, exit_status);
if (r < 0)
return r;
}
if (context->memory_ksm >= 0)
if (prctl(PR_SET_MEMORY_MERGE, context->memory_ksm) < 0) {
if (ERRNO_IS_NOT_SUPPORTED(errno))
log_exec_debug_errno(context,
params,
errno,
"KSM support not available, ignoring.");
else {
*exit_status = EXIT_KSM;
return log_exec_error_errno(context, params, errno, "Failed to set KSM: %m");
}
}
/* Drop groups as early as possible.
core: fix a couple of typos
2023-10-31 17:33:29 +01:00
* This needs to be done after PrivateDevices=yes setup as device nodes should be owned by the host's root.
core: move code from execute.c to exec-invoke.c No functional changes, only moving code that is only needed in exec_invoke, and adding new dependencies for seccomp/selinux/apparmor/pam in meson for the sd-executor binary.
2023-09-01 02:24:49 +01:00
* For non-root in a userns, devices will be owned by the user/group before the group change, and nobody. */
if (needs_setuid) {
_cleanup_free_ gid_t *gids_to_enforce = NULL;
int ngids_to_enforce = 0;
ngids_to_enforce = merge_gid_lists(supplementary_gids,
ngids,
gids_after_pam,
ngids_after_pam,
&gids_to_enforce);
if (ngids_to_enforce < 0) {
core/exec-invoke: use correct exit status These calls can fail not only due to OOM.
2023-10-18 21:22:19 +08:00
*exit_status = EXIT_GROUP;
core: move code from execute.c to exec-invoke.c No functional changes, only moving code that is only needed in exec_invoke, and adding new dependencies for seccomp/selinux/apparmor/pam in meson for the sd-executor binary.
2023-09-01 02:24:49 +01:00
return log_exec_error_errno(context, params,
ngids_to_enforce,
"Failed to merge group lists. Group membership might be incorrect: %m");
}
r = enforce_groups(gid, gids_to_enforce, ngids_to_enforce);
if (r < 0) {
*exit_status = EXIT_GROUP;
return log_exec_error_errno(context, params, r, "Changing group credentials failed: %m");
}
}
/* If the user namespace was not set up above, try to do it now.
* It's preferred to set up the user namespace later (after all other namespaces) so as not to be
* restricted by rules pertaining to combining user namespaces with other namespaces (e.g. in the
* case of mount namespaces being less privileged when the mount point list is copied from a
* different user namespace). */
if (needs_sandboxing && context->private_users && !userns_set_up) {
r = setup_private_users(saved_uid, saved_gid, uid, gid);
if (r < 0) {
*exit_status = EXIT_USER;
return log_exec_error_errno(context, params, r, "Failed to set up user namespacing: %m");
}
}
/* Now that the mount namespace has been set up and privileges adjusted, let's look for the thing we
* shall execute. */
_cleanup_free_ char *executable = NULL;
_cleanup_close_ int executable_fd = -EBADF;
r = find_executable_full(command->path, /* root= */ NULL, context->exec_search_path, false, &executable, &executable_fd);
if (r < 0) {
if (r != -ENOMEM && (command->flags & EXEC_COMMAND_IGNORE_FAILURE)) {
log_exec_struct_errno(context, params, LOG_INFO, r,
"MESSAGE_ID=" SD_MESSAGE_SPAWN_FAILED_STR,
LOG_EXEC_INVOCATION_ID(params),
LOG_EXEC_MESSAGE(params,
"Executable %s missing, skipping: %m",
command->path),
"EXECUTABLE=%s", command->path);
*exit_status = EXIT_SUCCESS;
return 0;
}
*exit_status = EXIT_EXEC;
return log_exec_struct_errno(context, params, LOG_INFO, r,
"MESSAGE_ID=" SD_MESSAGE_SPAWN_FAILED_STR,
LOG_EXEC_INVOCATION_ID(params),
LOG_EXEC_MESSAGE(params,
"Failed to locate executable %s: %m",
command->path),
"EXECUTABLE=%s", command->path);
}
r = add_shifted_fd(keep_fds, ELEMENTSOF(keep_fds), &n_keep_fds, executable_fd, &executable_fd);
if (r < 0) {
*exit_status = EXIT_FDS;
return log_exec_error_errno(context, params, r, "Failed to shift fd and set FD_CLOEXEC: %m");
}
#if HAVE_SELINUX
if (needs_sandboxing && use_selinux && params->selinux_context_net) {
int fd = -EBADF;
if (socket_fd >= 0)
fd = socket_fd;
else if (params->n_socket_fds == 1)
/* If stdin is not connected to a socket but we are triggered by exactly one socket unit then we
* use context from that fd to compute the label. */
fd = params->fds[0];
if (fd >= 0) {
r = mac_selinux_get_child_mls_label(fd, executable, context->selinux_context, &mac_selinux_context_net);
if (r < 0) {
if (!context->selinux_context_ignore) {
*exit_status = EXIT_SELINUX_CONTEXT;
return log_exec_error_errno(context,
params,
r,
"Failed to determine SELinux context: %m");
}
log_exec_debug_errno(context,
params,
r,
"Failed to determine SELinux context, ignoring: %m");
}
}
}
#endif
/* We repeat the fd closing here, to make sure that nothing is leaked from the PAM modules. Note that
* we are more aggressive this time, since we don't need socket_fd and the netns and ipcns fds any
* more. We do keep exec_fd however, if we have it, since we need to keep it open until the final
exec-invoke: don't double-close FDs on error When a late error occurs in sd-executor, the cleanup-on-close of the context structs happen, but at that time all FDs might have already been closed via close_all_fds(), so a double-close happens. This can be seen when DynamicUser is enabled, with a non-existing WorkingDirectory. Invalidate the FDs in the context structs if close_all_fds succeeds.
2023-10-27 16:33:49 +01:00
* execve(). But first, close the remaining sockets in the context objects. */
exec_runtime_close(runtime);
exec_params_close(params);
core: move code from execute.c to exec-invoke.c No functional changes, only moving code that is only needed in exec_invoke, and adding new dependencies for seccomp/selinux/apparmor/pam in meson for the sd-executor binary.
2023-09-01 02:24:49 +01:00
r = close_all_fds(keep_fds, n_keep_fds);
if (r >= 0)
r = shift_fds(fds, n_fds);
if (r >= 0)
r = flags_fds(fds, n_socket_fds, n_fds, context->non_blocking);
if (r < 0) {
*exit_status = EXIT_FDS;
return log_exec_error_errno(context, params, r, "Failed to adjust passed file descriptors: %m");
}
/* At this point, the fds we want to pass to the program are all ready and set up, with O_CLOEXEC turned off
* and at the right fd numbers. The are no other fds open, with one exception: the exec_fd if it is defined,
* and it has O_CLOEXEC set, after all we want it to be closed by the execve(), so that our parent knows we
* came this far. */
secure_bits = context->secure_bits;
if (needs_sandboxing) {
uint64_t bset;
/* Set the RTPRIO resource limit to 0, but only if nothing else was explicitly requested.
* (Note this is placed after the general resource limit initialization, see above, in order
* to take precedence.) */
if (context->restrict_realtime && !context->rlimit[RLIMIT_RTPRIO]) {
if (setrlimit(RLIMIT_RTPRIO, &RLIMIT_MAKE_CONST(0)) < 0) {
*exit_status = EXIT_LIMITS;
return log_exec_error_errno(context, params, errno, "Failed to adjust RLIMIT_RTPRIO resource limit: %m");
}
}
#if ENABLE_SMACK
/* LSM Smack needs the capability CAP_MAC_ADMIN to change the current execution security context of the
* process. This is the latest place before dropping capabilities. Other MAC context are set later. */
if (use_smack && context->smack_process_label) {
r = setup_smack(params, context, executable_fd);
if (r < 0 && !context->smack_process_label_ignore) {
*exit_status = EXIT_SMACK_PROCESS_LABEL;
return log_exec_error_errno(context, params, r, "Failed to set SMACK process label: %m");
}
}
#endif
bset = context->capability_bounding_set;
/* If the ambient caps hack is enabled (which means the kernel can't do them, and the user asked for
* our magic fallback), then let's add some extra caps, so that the service can drop privs of its own,
* instead of us doing that */
if (needs_ambient_hack)
bset |= (UINT64_C(1) << CAP_SETPCAP) |
(UINT64_C(1) << CAP_SETUID) |
(UINT64_C(1) << CAP_SETGID);
core: allow using seccomp without no_new_privs when unprivileged Until now, using any form of seccomp while being unprivileged (User=) resulted in systemd enabling no_new_privs. There's no need for doing this because: * We trust the filters we apply * If User= is set and a process wants to apply a new seccomp filter, it will need to set no_new_privs itself An example of application that might want seccomp + !no_new_privs is a program that wants to run as an unprivileged user but uses file capabilities to start a web server on a privileged port while benefitting from a restrictive seccomp profile. We now keep the privileges needed to do seccomp before calling enforce_user() and drop them after the seccomp filters are applied. If the syscall filter doesn't allow the needed syscalls to drop the privileges, we keep the previous behavior by enabling no_new_privs.
2023-11-07 11:06:56 +01:00
#if HAVE_SECCOMP
/* If the service has any form of a seccomp filter and it allows dropping privileges, we'll
* keep the needed privileges to apply it even if we're not root. */
if (needs_setuid &&
uid_is_valid(uid) &&
context_has_seccomp(context) &&
seccomp_allows_drop_privileges(context)) {
keep_seccomp_privileges = true;
if (prctl(PR_SET_KEEPCAPS, 1) < 0) {
*exit_status = EXIT_USER;
return log_exec_error_errno(context, params, errno, "Failed to enable keep capabilities flag: %m");
}
/* Save the current bounding set so we can restore it after applying the seccomp
* filter */
saved_bset = bset;
bset |= (UINT64_C(1) << CAP_SYS_ADMIN) |
(UINT64_C(1) << CAP_SETPCAP);
}
#endif
core: move code from execute.c to exec-invoke.c No functional changes, only moving code that is only needed in exec_invoke, and adding new dependencies for seccomp/selinux/apparmor/pam in meson for the sd-executor binary.
2023-09-01 02:24:49 +01:00
if (!cap_test_all(bset)) {
r = capability_bounding_set_drop(bset, /* right_now= */ false);
if (r < 0) {
*exit_status = EXIT_CAPABILITIES;
return log_exec_error_errno(context, params, r, "Failed to drop capabilities: %m");
}
}
/* Ambient capabilities are cleared during setresuid() (in enforce_user()) even with
* keep-caps set.
*
* To be able to raise the ambient capabilities after setresuid() they have to be added to
* the inherited set and keep caps has to be set (done in enforce_user()). After setresuid()
* the ambient capabilities can be raised as they are present in the permitted and
* inhertiable set. However it is possible that someone wants to set ambient capabilities
* without changing the user, so we also set the ambient capabilities here.
*
* The requested ambient capabilities are raised in the inheritable set if the second
* argument is true. */
if (!needs_ambient_hack) {
r = capability_ambient_set_apply(capability_ambient_set, /* also_inherit= */ true);
if (r < 0) {
*exit_status = EXIT_CAPABILITIES;
return log_exec_error_errno(context, params, r, "Failed to apply ambient capabilities (before UID change): %m");
}
}
}
/* chroot to root directory first, before we lose the ability to chroot */
r = apply_root_directory(context, params, runtime, needs_mount_namespace, exit_status);
if (r < 0)
return log_exec_error_errno(context, params, r, "Chrooting to the requested root directory failed: %m");
if (needs_setuid) {
if (uid_is_valid(uid)) {
r = enforce_user(context, uid, capability_ambient_set);
if (r < 0) {
*exit_status = EXIT_USER;
return log_exec_error_errno(context, params, r, "Failed to change UID to " UID_FMT ": %m", uid);
}
core: allow using seccomp without no_new_privs when unprivileged Until now, using any form of seccomp while being unprivileged (User=) resulted in systemd enabling no_new_privs. There's no need for doing this because: * We trust the filters we apply * If User= is set and a process wants to apply a new seccomp filter, it will need to set no_new_privs itself An example of application that might want seccomp + !no_new_privs is a program that wants to run as an unprivileged user but uses file capabilities to start a web server on a privileged port while benefitting from a restrictive seccomp profile. We now keep the privileges needed to do seccomp before calling enforce_user() and drop them after the seccomp filters are applied. If the syscall filter doesn't allow the needed syscalls to drop the privileges, we keep the previous behavior by enabling no_new_privs.
2023-11-07 11:06:56 +01:00
if (keep_seccomp_privileges) {
r = drop_capability(CAP_SETUID);
if (r < 0) {
*exit_status = EXIT_USER;
return log_exec_error_errno(context, params, r, "Failed to drop CAP_SETUID: %m");
}
r = keep_capability(CAP_SYS_ADMIN);
if (r < 0) {
*exit_status = EXIT_USER;
return log_exec_error_errno(context, params, r, "Failed to keep CAP_SYS_ADMIN: %m");
}
r = keep_capability(CAP_SETPCAP);
if (r < 0) {
*exit_status = EXIT_USER;
return log_exec_error_errno(context, params, r, "Failed to keep CAP_SETPCAP: %m");
}
}
core: move code from execute.c to exec-invoke.c No functional changes, only moving code that is only needed in exec_invoke, and adding new dependencies for seccomp/selinux/apparmor/pam in meson for the sd-executor binary.
2023-09-01 02:24:49 +01:00
if (!needs_ambient_hack && capability_ambient_set != 0) {
/* Raise the ambient capabilities after user change. */
r = capability_ambient_set_apply(capability_ambient_set, /* also_inherit= */ false);
if (r < 0) {
*exit_status = EXIT_CAPABILITIES;
return log_exec_error_errno(context, params, r, "Failed to apply ambient capabilities (after UID change): %m");
}
}
}
}
/* Apply working directory here, because the working directory might be on NFS and only the user running
* this service might have the correct privilege to change to the working directory */
r = apply_working_directory(context, params, runtime, home, exit_status);
if (r < 0)
return log_exec_error_errno(context, params, r, "Changing to the requested working directory failed: %m");
if (needs_sandboxing) {
/* Apply other MAC contexts late, but before seccomp syscall filtering, as those should really be last to
* influence our own codepaths as little as possible. Moreover, applying MAC contexts usually requires
* syscalls that are subject to seccomp filtering, hence should probably be applied before the syscalls
* are restricted. */
#if HAVE_SELINUX
if (use_selinux) {
char *exec_context = mac_selinux_context_net ?: context->selinux_context;
if (exec_context) {
r = setexeccon(exec_context);
if (r < 0) {
if (!context->selinux_context_ignore) {
*exit_status = EXIT_SELINUX_CONTEXT;
return log_exec_error_errno(context, params, r, "Failed to change SELinux context to %s: %m", exec_context);
}
log_exec_debug_errno(context,
params,
r,
"Failed to change SELinux context to %s, ignoring: %m",
exec_context);
}
}
}
#endif
#if HAVE_APPARMOR
if (use_apparmor && context->apparmor_profile) {
r = aa_change_onexec(context->apparmor_profile);
if (r < 0 && !context->apparmor_profile_ignore) {
*exit_status = EXIT_APPARMOR_PROFILE;
return log_exec_error_errno(context,
params,
errno,
"Failed to prepare AppArmor profile change to %s: %m",
context->apparmor_profile);
}
}
#endif
/* PR_GET_SECUREBITS is not privileged, while PR_SET_SECUREBITS is. So to suppress potential
* EPERMs we'll try not to call PR_SET_SECUREBITS unless necessary. Setting securebits
* requires CAP_SETPCAP. */
if (prctl(PR_GET_SECUREBITS) != secure_bits) {
/* CAP_SETPCAP is required to set securebits. This capability is raised into the
* effective set here.
*
* The effective set is overwritten during execve() with the following values:
*
* - ambient set (for non-root processes)
*
* - (inheritable | bounding) set for root processes)
*
* Hence there is no security impact to raise it in the effective set before execve
*/
r = capability_gain_cap_setpcap(/* return_caps= */ NULL);
if (r < 0) {
*exit_status = EXIT_CAPABILITIES;
return log_exec_error_errno(context, params, r, "Failed to gain CAP_SETPCAP for setting secure bits");
}
if (prctl(PR_SET_SECUREBITS, secure_bits) < 0) {
*exit_status = EXIT_SECUREBITS;
return log_exec_error_errno(context, params, errno, "Failed to set process secure bits: %m");
}
}
if (context_has_no_new_privileges(context))
if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) < 0) {
*exit_status = EXIT_NO_NEW_PRIVILEGES;
return log_exec_error_errno(context, params, errno, "Failed to disable new privileges: %m");
}
#if HAVE_SECCOMP
r = apply_address_families(context, params);
if (r < 0) {
*exit_status = EXIT_ADDRESS_FAMILIES;
return log_exec_error_errno(context, params, r, "Failed to restrict address families: %m");
}
r = apply_memory_deny_write_execute(context, params);
if (r < 0) {
*exit_status = EXIT_SECCOMP;
return log_exec_error_errno(context, params, r, "Failed to disable writing to executable memory: %m");
}
r = apply_restrict_realtime(context, params);
if (r < 0) {
*exit_status = EXIT_SECCOMP;
return log_exec_error_errno(context, params, r, "Failed to apply realtime restrictions: %m");
}
r = apply_restrict_suid_sgid(context, params);
if (r < 0) {
*exit_status = EXIT_SECCOMP;
return log_exec_error_errno(context, params, r, "Failed to apply SUID/SGID restrictions: %m");
}
r = apply_restrict_namespaces(context, params);
if (r < 0) {
*exit_status = EXIT_SECCOMP;
return log_exec_error_errno(context, params, r, "Failed to apply namespace restrictions: %m");
}
r = apply_protect_sysctl(context, params);
if (r < 0) {
*exit_status = EXIT_SECCOMP;
return log_exec_error_errno(context, params, r, "Failed to apply sysctl restrictions: %m");
}
r = apply_protect_kernel_modules(context, params);
if (r < 0) {
*exit_status = EXIT_SECCOMP;
return log_exec_error_errno(context, params, r, "Failed to apply module loading restrictions: %m");
}
r = apply_protect_kernel_logs(context, params);
if (r < 0) {
*exit_status = EXIT_SECCOMP;
return log_exec_error_errno(context, params, r, "Failed to apply kernel log restrictions: %m");
}
r = apply_protect_clock(context, params);
if (r < 0) {
*exit_status = EXIT_SECCOMP;
return log_exec_error_errno(context, params, r, "Failed to apply clock restrictions: %m");
}
r = apply_private_devices(context, params);
if (r < 0) {
*exit_status = EXIT_SECCOMP;
return log_exec_error_errno(context, params, r, "Failed to set up private devices: %m");
}
r = apply_syscall_archs(context, params);
if (r < 0) {
*exit_status = EXIT_SECCOMP;
return log_exec_error_errno(context, params, r, "Failed to apply syscall architecture restrictions: %m");
}
r = apply_lock_personality(context, params);
if (r < 0) {
*exit_status = EXIT_SECCOMP;
return log_exec_error_errno(context, params, r, "Failed to lock personalities: %m");
}
r = apply_syscall_log(context, params);
if (r < 0) {
*exit_status = EXIT_SECCOMP;
return log_exec_error_errno(context, params, r, "Failed to apply system call log filters: %m");
}
core: allow using seccomp without no_new_privs when unprivileged Until now, using any form of seccomp while being unprivileged (User=) resulted in systemd enabling no_new_privs. There's no need for doing this because: * We trust the filters we apply * If User= is set and a process wants to apply a new seccomp filter, it will need to set no_new_privs itself An example of application that might want seccomp + !no_new_privs is a program that wants to run as an unprivileged user but uses file capabilities to start a web server on a privileged port while benefitting from a restrictive seccomp profile. We now keep the privileges needed to do seccomp before calling enforce_user() and drop them after the seccomp filters are applied. If the syscall filter doesn't allow the needed syscalls to drop the privileges, we keep the previous behavior by enabling no_new_privs.
2023-11-07 11:06:56 +01:00
#endif
core: move code from execute.c to exec-invoke.c No functional changes, only moving code that is only needed in exec_invoke, and adding new dependencies for seccomp/selinux/apparmor/pam in meson for the sd-executor binary.
2023-09-01 02:24:49 +01:00
core: allow using seccomp without no_new_privs when unprivileged Until now, using any form of seccomp while being unprivileged (User=) resulted in systemd enabling no_new_privs. There's no need for doing this because: * We trust the filters we apply * If User= is set and a process wants to apply a new seccomp filter, it will need to set no_new_privs itself An example of application that might want seccomp + !no_new_privs is a program that wants to run as an unprivileged user but uses file capabilities to start a web server on a privileged port while benefitting from a restrictive seccomp profile. We now keep the privileges needed to do seccomp before calling enforce_user() and drop them after the seccomp filters are applied. If the syscall filter doesn't allow the needed syscalls to drop the privileges, we keep the previous behavior by enabling no_new_privs.
2023-11-07 11:06:56 +01:00
#if HAVE_LIBBPF
r = apply_restrict_filesystems(context, params);
if (r < 0) {
*exit_status = EXIT_BPF;
return log_exec_error_errno(context, params, r, "Failed to restrict filesystems: %m");
}
#endif
#if HAVE_SECCOMP
/* This really should remain as close to the execve() as possible, to make sure our own code is unaffected
core: move code from execute.c to exec-invoke.c No functional changes, only moving code that is only needed in exec_invoke, and adding new dependencies for seccomp/selinux/apparmor/pam in meson for the sd-executor binary.
2023-09-01 02:24:49 +01:00
* by the filter as little as possible. */
r = apply_syscall_filter(context, params, needs_ambient_hack);
if (r < 0) {
*exit_status = EXIT_SECCOMP;
return log_exec_error_errno(context, params, r, "Failed to apply system call filters: %m");
}
core: allow using seccomp without no_new_privs when unprivileged Until now, using any form of seccomp while being unprivileged (User=) resulted in systemd enabling no_new_privs. There's no need for doing this because: * We trust the filters we apply * If User= is set and a process wants to apply a new seccomp filter, it will need to set no_new_privs itself An example of application that might want seccomp + !no_new_privs is a program that wants to run as an unprivileged user but uses file capabilities to start a web server on a privileged port while benefitting from a restrictive seccomp profile. We now keep the privileges needed to do seccomp before calling enforce_user() and drop them after the seccomp filters are applied. If the syscall filter doesn't allow the needed syscalls to drop the privileges, we keep the previous behavior by enabling no_new_privs.
2023-11-07 11:06:56 +01:00
if (keep_seccomp_privileges) {
/* Restore the capability bounding set with what's expected from the service + the
* ambient capabilities hack */
if (!cap_test_all(saved_bset)) {
r = capability_bounding_set_drop(saved_bset, /* right_now= */ false);
if (r < 0) {
*exit_status = EXIT_CAPABILITIES;
return log_exec_error_errno(context, params, r, "Failed to drop bset capabilities: %m");
}
}
/* Only drop CAP_SYS_ADMIN if it's not in the bounding set, otherwise we'll break
* applications that use it. */
if (!FLAGS_SET(saved_bset, (UINT64_C(1) << CAP_SYS_ADMIN))) {
r = drop_capability(CAP_SYS_ADMIN);
if (r < 0) {
*exit_status = EXIT_USER;
return log_exec_error_errno(context, params, r, "Failed to drop CAP_SYS_ADMIN: %m");
}
}
/* Only drop CAP_SETPCAP if it's not in the bounding set, otherwise we'll break
* applications that use it. */
if (!FLAGS_SET(saved_bset, (UINT64_C(1) << CAP_SETPCAP))) {
r = drop_capability(CAP_SETPCAP);
if (r < 0) {
*exit_status = EXIT_USER;
return log_exec_error_errno(context, params, r, "Failed to drop CAP_SETPCAP: %m");
}
}
if (prctl(PR_SET_KEEPCAPS, 0) < 0) {
*exit_status = EXIT_USER;
return log_exec_error_errno(context, params, errno, "Failed to drop keep capabilities flag: %m");
}
core: move code from execute.c to exec-invoke.c No functional changes, only moving code that is only needed in exec_invoke, and adding new dependencies for seccomp/selinux/apparmor/pam in meson for the sd-executor binary.
2023-09-01 02:24:49 +01:00
}
#endif
}
if (!strv_isempty(context->unset_environment)) {
char **ee = NULL;
ee = strv_env_delete(accum_env, 1, context->unset_environment);
if (!ee) {
*exit_status = EXIT_MEMORY;
return log_oom();
}
strv_free_and_replace(accum_env, ee);
}
if (!FLAGS_SET(command->flags, EXEC_COMMAND_NO_ENV_EXPAND)) {
_cleanup_strv_free_ char **unset_variables = NULL, **bad_variables = NULL;
r = replace_env_argv(command->argv, accum_env, &replaced_argv, &unset_variables, &bad_variables);
if (r < 0) {
*exit_status = EXIT_MEMORY;
return log_exec_error_errno(context,
params,
r,
"Failed to replace environment variables: %m");
}
final_argv = replaced_argv;
if (!strv_isempty(unset_variables)) {
_cleanup_free_ char *ju = strv_join(unset_variables, ", ");
log_exec_warning(context,
params,
"Referenced but unset environment variable evaluates to an empty string: %s",
strna(ju));
}
if (!strv_isempty(bad_variables)) {
_cleanup_free_ char *jb = strv_join(bad_variables, ", ");
log_exec_warning(context,
params,
"Invalid environment variable name evaluates to an empty string: %s",
strna(jb));
}
} else
final_argv = command->argv;
log_command_line(context, params, "Executing", executable, final_argv);
if (exec_fd >= 0) {
uint8_t hot = 1;
/* We have finished with all our initializations. Let's now let the manager know that. From this point
* on, if the manager sees POLLHUP on the exec_fd, then execve() was successful. */
if (write(exec_fd, &hot, sizeof(hot)) < 0) {
*exit_status = EXIT_EXEC;
return log_exec_error_errno(context, params, errno, "Failed to enable exec_fd: %m");
}
}
r = fexecve_or_execve(executable_fd, executable, final_argv, accum_env);
if (exec_fd >= 0) {
uint8_t hot = 0;
/* The execve() failed. This means the exec_fd is still open. Which means we need to tell the manager
* that POLLHUP on it no longer means execve() succeeded. */
if (write(exec_fd, &hot, sizeof(hot)) < 0) {
*exit_status = EXIT_EXEC;
return log_exec_error_errno(context, params, errno, "Failed to disable exec_fd: %m");
}
}
*exit_status = EXIT_EXEC;
return log_exec_error_errno(context, params, r, "Failed to execute %s: %m", executable);
}
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