1#define _GNU_SOURCE
2#include <unistd.h>
3#include <signal.h>
4#include "syscall.h"
5#include "libc.h"
6
7struct ctx {
8 size_t count;
9 const gid_t *list;
10 int ret;
11};
12
13static void do_setgroups(void *p)
14{
15 struct ctx *c = p;
16 if (c->ret<0) return;
17 int ret = __syscall(SYS_setgroups, c->count, c->list);
18 if (ret && !c->ret) {
19 /* If one thread fails to set groups after another has already
20 * succeeded, forcibly killing the process is the only safe
21 * thing to do. State is inconsistent and dangerous. Use
22 * SIGKILL because it is uncatchable. */
23 __block_all_sigs(0);
24 __syscall(SYS_kill, __syscall(SYS_getpid), SIGKILL);
25 }
26 c->ret = ret;
27}
28
29int setgroups(size_t count, const gid_t list[])
30{
31 /* ret is initially nonzero so that failure of the first thread does not
32 * trigger the safety kill above. */
33 struct ctx c = { .count = count, .list = list, .ret = 1 };
34 __synccall(do_setgroups, &c);
35 return __syscall_ret(c.ret);
36}