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Merge pull request #14853 from floppym/issue9806

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safe_fork: unblock most signals before waiting for child
This commit is contained in:
Lennart Poettering 2020-03-30 17:27:55 +02:00 committed by GitHub
parent fef7397022 4b3abcd019
commit 4c287f9a0b
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GPG key ID: 4AEE18F83AFDEB23
1 changed files with 23 additions and 14 deletions
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37
src/basic/process-util.c
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@ -1178,6 +1178,11 @@ int must_be_root(void) {
return log_error_errno(SYNTHETIC_ERRNO(EPERM), "Need to be root.");
}
static void restore_sigsetp(sigset_t **ssp) {
if (*ssp)
(void) sigprocmask(SIG_SETMASK, *ssp, NULL);
}
int safe_fork_full(
const char *name,
const int except_fds[],
@ -1187,7 +1192,8 @@ int safe_fork_full(
pid_t original_pid, pid;
sigset_t saved_ss, ss;
bool block_signals = false;
_cleanup_(restore_sigsetp) sigset_t *saved_ssp = NULL;
bool block_signals = false, block_all = false;
int prio, r;
/* A wrapper around fork(), that does a couple of important initializations in addition to mere forking. Always
@ -1202,7 +1208,7 @@ int safe_fork_full(
* be sure that SIGTERMs are not lost we might send to the child. */
assert_se(sigfillset(&ss) >= 0);
block_signals = true;
block_signals = block_all = true;
} else if (flags & FORK_WAIT) {
/* Let's block SIGCHLD at least, so that we can safely watch for the child process */
@ -1212,28 +1218,31 @@ int safe_fork_full(
block_signals = true;
}
if (block_signals)
if (block_signals) {
if (sigprocmask(SIG_SETMASK, &ss, &saved_ss) < 0)
return log_full_errno(prio, errno, "Failed to set signal mask: %m");
saved_ssp = &saved_ss;
}
if (flags & FORK_NEW_MOUNTNS)
pid = raw_clone(SIGCHLD|CLONE_NEWNS);
else
pid = fork();
if (pid < 0) {
r = -errno;
if (block_signals) /* undo what we did above */
(void) sigprocmask(SIG_SETMASK, &saved_ss, NULL);
return log_full_errno(prio, r, "Failed to fork: %m");
}
if (pid < 0)
return log_full_errno(prio, errno, "Failed to fork: %m");
if (pid > 0) {
/* We are in the parent process */
log_debug("Successfully forked off '%s' as PID " PID_FMT ".", strna(name), pid);
if (flags & FORK_WAIT) {
if (block_all) {
/* undo everything except SIGCHLD */
ss = saved_ss;
assert_se(sigaddset(&ss, SIGCHLD) >= 0);
(void) sigprocmask(SIG_SETMASK, &ss, NULL);
}
r = wait_for_terminate_and_check(name, pid, (flags & FORK_LOG ? WAIT_LOG : 0));
if (r < 0)
return r;
@ -1241,9 +1250,6 @@ int safe_fork_full(
return -EPROTO;
}
if (block_signals) /* undo what we did above */
(void) sigprocmask(SIG_SETMASK, &saved_ss, NULL);
if (ret_pid)
*ret_pid = pid;
@ -1252,6 +1258,9 @@ int safe_fork_full(
/* We are in the child process */
/* Restore signal mask manually */
saved_ssp = NULL;
if (flags & FORK_REOPEN_LOG) {
/* Close the logs if requested, before we log anything. And make sure we reopen it if needed. */
log_close();