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lib: hard-fail creating threads before fork()

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Creating any threads before we fork() into the background (if `-d` is
given) is an extremely dangerous footgun;  the threads are created in
the parent and terminated when that exits.

This is extra dangerous because while testing, you'd often run the
daemon in foreground without `-d`, and everything works as expected.

Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
This commit is contained in:
David Lamparter 2021-04-22 12:10:27 +02:00
parent 159246be24
commit 38554d3ae6
3 changed files with 10 additions and 0 deletions
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3
lib/frr_pthread.c
View file

@ -28,6 +28,7 @@
#include "memory.h"
#include "linklist.h"
#include "zlog.h"
#include "libfrr.h"
#include "libfrr_trace.h"
DEFINE_MTYPE_STATIC(LIB, FRR_PTHREAD, "FRR POSIX Thread");
@ -162,6 +163,8 @@ int frr_pthread_run(struct frr_pthread *fpt, const pthread_attr_t *attr)
int ret;
sigset_t oldsigs, blocksigs;
assert(frr_is_after_fork || !"trying to start thread before fork()");
/* Ensure we never handle signals on a background thread by blocking
* everything here (new thread inherits signal mask)
*/

5
lib/libfrr.c
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@ -70,6 +70,8 @@ static char dbfile_default[512];
#endif
static char vtypath_default[512];
/* cleared in frr_preinit(), then re-set after daemonizing */
bool frr_is_after_fork = true;
bool debug_memstats_at_exit = false;
static bool nodetach_term, nodetach_daemon;
static uint64_t startup_fds;
@ -308,6 +310,7 @@ void frr_init_vtydir(void)
void frr_preinit(struct frr_daemon_info *daemon, int argc, char **argv)
{
di = daemon;
frr_is_after_fork = false;
/* basename(), opencoded. */
char *p = strrchr(argv[0], '/');
@ -990,6 +993,8 @@ void frr_config_fork(void)
if (di->daemon_mode || di->terminal)
frr_daemonize();
frr_is_after_fork = true;
if (!di->pid_file)
di->pid_file = pidfile_default;
pid_output(di->pid_file);

2
lib/libfrr.h
View file

@ -172,6 +172,8 @@ extern const char frr_scriptdir[];
extern char frr_protoname[];
extern char frr_protonameinst[];
/* always set in the spot where we *would* fork even if we don't do so */
extern bool frr_is_after_fork;
extern bool debug_memstats_at_exit;