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Merge pull request #6518 from joukewitteveen/process-rename

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process-util: update the end pointer of the process name on rename
This commit is contained in:
Evgeny Vereshchagin
2017-08-04 14:54:47 +03:00
committed by GitHub
parent 785889e56d 049c884a3b
commit a93e2f65eb
2 changed files with 73 additions and 38 deletions
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26
src/basic/process-util.c
View File

@@ -312,19 +312,18 @@ int rename_process(const char name[]) {
/* Third step, completely replace the argv[] array the kernel maintains for us. This requires privileges, but
* has the advantage that the argv[] array is exactly what we want it to be, and not filled up with zeros at
* the end. This is the best option for changing /proc/self/cmdline. */
if (mm_size < l+1) {
/* Let's not bother with this if we don't have euid == 0. Strictly speaking we should check for the
* CAP_SYS_RESOURCE capability which is independent of the euid. In our own code the capability generally is
* present only for euid == 0, hence let's use this as quick bypass check, to avoid calling mmap() if
* PR_SET_MM_ARG_{START,END} fails with EPERM later on anyway. After all geteuid() is dead cheap to call, but
* mmap() is not. */
if (geteuid() != 0)
log_debug("Skipping PR_SET_MM, as we don't have privileges.");
else if (mm_size < l+1) {
size_t nn_size;
char *nn;
/* Let's not bother with this if we don't have euid == 0. Strictly speaking if people do weird stuff
* with capabilities this could work even for euid != 0, but our own code generally doesn't do that,
* hence let's use this as quick bypass check, to avoid calling mmap() if PR_SET_MM_ARG_START fails
* with EPERM later on anyway. After all geteuid() is dead cheap to call, but mmap() is not. */
if (geteuid() != 0) {
log_debug("Skipping PR_SET_MM_ARG_START, as we don't have privileges.");
goto use_saved_argv;
}
nn_size = PAGE_ALIGN(l+1);
nn = mmap(NULL, nn_size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
if (nn == MAP_FAILED) {
@@ -351,9 +350,14 @@ int rename_process(const char name[]) {
mm = nn;
mm_size = nn_size;
} else
} else {
strncpy(mm, name, mm_size);
/* Update the end pointer, continuing regardless of any failure. */
if (prctl(PR_SET_MM, PR_SET_MM_ARG_END, (unsigned long) mm + l + 1, 0, 0) < 0)
log_debug_errno(errno, "PR_SET_MM_ARG_END failed, proceeding without: %m");
}
use_saved_argv:
/* Fourth step: in all cases we'll also update the original argv[], so that our own code gets it right too if
* it still looks here */

85
src/test/test-process-util.c
View File

@@ -355,11 +355,59 @@ static void test_get_process_cmdline_harder(void) {
_exit(0);
}
static void test_rename_process_one(const char *p, int ret) {
static void test_rename_process_now(const char *p, int ret) {
_cleanup_free_ char *comm = NULL, *cmdline = NULL;
pid_t pid;
int r;
r = rename_process(p);
assert_se(r == ret ||
(ret == 0 && r >= 0) ||
(ret > 0 && r > 0));
if (r < 0)
return;
#ifdef HAVE_VALGRIND_VALGRIND_H
/* see above, valgrind is weird, we can't verify what we are doing here */
if (RUNNING_ON_VALGRIND)
return;
#endif
assert_se(get_process_comm(0, &comm) >= 0);
log_info("comm = <%s>", comm);
assert_se(strneq(comm, p, 15));
assert_se(get_process_cmdline(0, 0, false, &cmdline) >= 0);
/* we cannot expect cmdline to be renamed properly without privileges */
if (geteuid() == 0) {
log_info("cmdline = <%s>", cmdline);
assert_se(strneq(p, cmdline, strlen("test-process-util")));
assert_se(startswith(p, cmdline));
} else
log_info("cmdline = <%s> (not verified)", cmdline);
}
static void test_rename_process_one(const char *p, int ret) {
siginfo_t si;
pid_t pid;
pid = fork();
assert_se(pid >= 0);
if (pid == 0) {
/* child */
test_rename_process_now(p, ret);
_exit(EXIT_SUCCESS);
}
assert_se(wait_for_terminate(pid, &si) >= 0);
assert_se(si.si_code == CLD_EXITED);
assert_se(si.si_status == EXIT_SUCCESS);
}
static void test_rename_process_multi(void) {
pid_t pid;
pid = fork();
assert_se(pid >= 0);
@@ -374,31 +422,13 @@ static void test_rename_process_one(const char *p, int ret) {
}
/* child */
r = rename_process(p);
assert_se(r == ret ||
(ret == 0 && r >= 0) ||
(ret > 0 && r > 0));
if (r < 0)
goto finish;
#ifdef HAVE_VALGRIND_VALGRIND_H
/* see above, valgrind is weird, we can't verify what we are doing here */
if (RUNNING_ON_VALGRIND)
goto finish;
#endif
assert_se(get_process_comm(0, &comm) >= 0);
log_info("comm = <%s>", comm);
assert_se(strneq(comm, p, 15));
assert_se(get_process_cmdline(0, 0, false, &cmdline) >= 0);
log_info("cmdline = <%s>", cmdline);
assert_se(strneq(p, cmdline, strlen("test-process-util")));
assert_se(startswith(p, cmdline));
finish:
test_rename_process_now("one", 1);
test_rename_process_now("more", 0); /* longer than "one", hence truncated */
setresuid(99, 99, 99);
test_rename_process_now("time!", 0);
test_rename_process_now("0", 1); /* shorter than "one", should fit */
test_rename_process_one("", -EINVAL);
test_rename_process_one(NULL, -EINVAL);
_exit(EXIT_SUCCESS);
}
@@ -408,6 +438,7 @@ static void test_rename_process(void) {
test_rename_process_one("foo", 1); /* should always fit */
test_rename_process_one("this is a really really long process name, followed by some more words", 0); /* unlikely to fit */
test_rename_process_one("1234567", 1); /* should always fit */
test_rename_process_multi(); /* multiple invocations and dropped privileges */
}
static void test_getpid_cached(void) {