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| | #include <unistd.h>
#include <errno.h>
#include "syscall.h"
#include "libc.h"
#include "pthread_impl.h"
struct ctx {
int id, eid, sid;
int xid, err;
};
static int setxid_syscall(int xid, int id, int eid, int sid)
{
if (xid == xid_resuid) return __syscall(SYS_setresuid, id, eid, sid);
if (xid == xid_resgid) return __syscall(SYS_setresgid, id, eid, sid);
if (xid == xid_reuid) return __syscall(SYS_setreuid, id, eid);
if (xid == xid_regid) return __syscall(SYS_setregid, id, eid);
if (xid == xid_uid) return __syscall(SYS_setuid, id);
if (xid == xid_gid) return __syscall(SYS_setgid, id);
abort();
}
static void do_setxid(void *p)
{
struct ctx *c = p;
if (c->err>0) return;
int ret = -setxid_syscall(c->xid, c->id, c->eid, c->sid);
if (ret && !c->err) {
/* If one thread fails to set ids after another has already
* succeeded, forcibly killing the process is the only safe
* thing to do. State is inconsistent and dangerous. Use
* SIGKILL because it is uncatchable. */
__block_all_sigs(0);
__syscall(SYS_kill, __syscall(SYS_getpid), SIGKILL);
}
c->err = ret;
}
int __setxid(int xid, int id, int eid, int sid)
{
/* err is initially nonzero so that failure of the first thread does not
* trigger the safety kill above. */
struct ctx c = { .xid = xid, .id = id, .eid = eid, .sid = sid, .err = -1 };
__synccall(do_setxid, &c);
if (c.err) {
if (c.err>0) errno = c.err;
return -1;
}
return 0;
}
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