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