SymbX/systemd
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

tree-wide: introduce new safe_fork() helper and port everything over

Browse Source 
This adds a new safe_fork() wrapper around fork() and makes use of it
everywhere. The new wrapper does a couple of things we previously did
manually and separately in a safer, more correct and automatic way:

1. Optionally resets signal handlers/mask in the child

2. Sets a name on all processes we fork off right after forking off (and
   the patch assigns useful names for all processes we fork off now,
   following a systematic naming scheme: always enclosed in () – in order
   to indicate that these are not proper, exec()ed processes, but only
   forked off children, and if the process is long-running with only our
   own code, without execve()'ing something else, it gets am "sd-" prefix.)

3. Optionally closes all file descriptors in the child

4. Optionally sets a PR_SET_DEATHSIG to SIGTERM in the child, in a safe
   way so that the parent dying before this happens being handled
   safely.

5. Optionally reopens the logs

6. Optionally connects stdin/stdout/stderr to /dev/null

7. Debug logs about the forked off processes.
This commit is contained in:
Lennart Poettering
2017-12-25 11:48:21 +01:00
parent d8caff6db6
commit 4c253ed1ca
42 changed files with 448 additions and 507 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/core/execute.c
+10 -19
View File
@@ -1207,27 +1207,19 @@ static int setup_pam(
parent_pid = getpid_cached();
pam_pid = fork();
if (pam_pid < 0) {
r = -errno;
r = safe_fork("(sd-pam)", 0, &pam_pid);
if (r < 0)
goto fail;
}
if (pam_pid == 0) {
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);
/* This string must fit in 10 chars (i.e. the length
* of "/sbin/init"), to look pretty in /bin/ps */
rename_process("(sd-pam)");
/* 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. */
close_many(fds, n_fds);
/* 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.
@@ -1879,11 +1871,10 @@ static int setup_private_users(uid_t uid, gid_t gid) {
if (pipe2(errno_pipe, O_CLOEXEC) < 0)
return -errno;
pid = fork();
if (pid < 0)
return -errno;
if (pid == 0) {
r = safe_fork("(sd-userns)", FORK_RESET_SIGNALS|FORK_DEATHSIG, &pid);
if (r < 0)
return r;
if (r == 0) {
_cleanup_close_ int fd = -1;
const char *a;
pid_t ppid;