1 #include <unistd.h>
2 #include <errno.h>
3 #include "syscall.h"
4 #include "libc.h"
5 #include "pthread_impl.h"
6
7 struct ctx {
8 int id, eid, sid;
9 int nr, err;
10 };
11
do_setxid(void * p)12 static void do_setxid(void *p)
13 {
14 struct ctx *c = p;
15 if (c->err>0) return;
16 int ret = -__syscall(c->nr, c->id, c->eid, c->sid);
17 if (ret && !c->err) {
18 /* If one thread fails to set ids after another has already
19 * succeeded, forcibly killing the process is the only safe
20 * thing to do. State is inconsistent and dangerous. Use
21 * SIGKILL because it is uncatchable. */
22 __block_all_sigs(0);
23 __syscall(SYS_kill, __syscall(SYS_getpid), SIGKILL);
24 }
25 c->err = ret;
26 }
27
__setxid(int nr,int id,int eid,int sid)28 int __setxid(int nr, int id, int eid, int sid)
29 {
30 /* err is initially nonzero so that failure of the first thread does not
31 * trigger the safety kill above. */
32 struct ctx c = { .nr = nr, .id = id, .eid = eid, .sid = sid, .err = -1 };
33 __synccall(do_setxid, &c);
34 if (c.err) {
35 if (c.err>0) errno = c.err;
36 return -1;
37 }
38 return 0;
39 }
40