1*c9945492SAndroid Build Coastguard Worker #include <unistd.h>
2*c9945492SAndroid Build Coastguard Worker #include <signal.h>
3*c9945492SAndroid Build Coastguard Worker #include "syscall.h"
4*c9945492SAndroid Build Coastguard Worker #include "libc.h"
5*c9945492SAndroid Build Coastguard Worker
6*c9945492SAndroid Build Coastguard Worker struct ctx {
7*c9945492SAndroid Build Coastguard Worker int id, eid, sid;
8*c9945492SAndroid Build Coastguard Worker int nr, ret;
9*c9945492SAndroid Build Coastguard Worker };
10*c9945492SAndroid Build Coastguard Worker
do_setxid(void * p)11*c9945492SAndroid Build Coastguard Worker static void do_setxid(void *p)
12*c9945492SAndroid Build Coastguard Worker {
13*c9945492SAndroid Build Coastguard Worker struct ctx *c = p;
14*c9945492SAndroid Build Coastguard Worker if (c->ret<0) return;
15*c9945492SAndroid Build Coastguard Worker int ret = __syscall(c->nr, c->id, c->eid, c->sid);
16*c9945492SAndroid Build Coastguard Worker if (ret && !c->ret) {
17*c9945492SAndroid Build Coastguard Worker /* If one thread fails to set ids after another has already
18*c9945492SAndroid Build Coastguard Worker * succeeded, forcibly killing the process is the only safe
19*c9945492SAndroid Build Coastguard Worker * thing to do. State is inconsistent and dangerous. Use
20*c9945492SAndroid Build Coastguard Worker * SIGKILL because it is uncatchable. */
21*c9945492SAndroid Build Coastguard Worker __block_all_sigs(0);
22*c9945492SAndroid Build Coastguard Worker __syscall(SYS_kill, __syscall(SYS_getpid), SIGKILL);
23*c9945492SAndroid Build Coastguard Worker }
24*c9945492SAndroid Build Coastguard Worker c->ret = ret;
25*c9945492SAndroid Build Coastguard Worker }
26*c9945492SAndroid Build Coastguard Worker
__setxid(int nr,int id,int eid,int sid)27*c9945492SAndroid Build Coastguard Worker int __setxid(int nr, int id, int eid, int sid)
28*c9945492SAndroid Build Coastguard Worker {
29*c9945492SAndroid Build Coastguard Worker /* ret is initially nonzero so that failure of the first thread does not
30*c9945492SAndroid Build Coastguard Worker * trigger the safety kill above. */
31*c9945492SAndroid Build Coastguard Worker struct ctx c = { .nr = nr, .id = id, .eid = eid, .sid = sid, .ret = 1 };
32*c9945492SAndroid Build Coastguard Worker __synccall(do_setxid, &c);
33*c9945492SAndroid Build Coastguard Worker return __syscall_ret(c.ret > 0 ? -EAGAIN : c.ret);
34*c9945492SAndroid Build Coastguard Worker }
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