cuserid: support invocation with a null pointer argument

[musl] / src / unistd / setxid.c

diff --git a/src/unistd/setxid.c b/src/unistd/setxid.c
index 2f651a1..487c1a1 100644 (file)
--- a/src/unistd/setxid.c
+++ b/src/unistd/setxid.c
@@ -1,47 +1,34 @@
 #include <unistd.h>
-#include <errno.h>
-#include <sys/resource.h>
+#include <signal.h>
 #include "syscall.h"
 #include "libc.h"
 
 struct ctx {
        int id, eid, sid;
-       int nr, rlim, err;
+       int nr, ret;
 };
 
-/* We jump through hoops to eliminate the possibility of partial failures. */
-
-int __setrlimit(int, const struct rlimit *);
-
 static void do_setxid(void *p)
 {
        struct ctx *c = p;
-       if (c->err) return;
-       if (c->rlim && c->id >= 0 && c->id != getuid()) {
-               struct rlimit inf = { RLIM_INFINITY, RLIM_INFINITY }, old;
-               getrlimit(RLIMIT_NPROC, &old);
-               if ((c->err = -__setrlimit(RLIMIT_NPROC, &inf)) && libc.threads_minus_1)
-                       return;
-               c->err = -__syscall(c->nr, c->id, c->eid, c->sid);
-               __setrlimit(RLIMIT_NPROC, &old);
-               return;
+       if (c->ret<0) return;
+       int ret = __syscall(c->nr, c->id, c->eid, c->sid);
+       if (ret && !c->ret) {
+               /* 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 = -__syscall(c->nr, c->id, c->eid, c->sid);
+       c->ret = ret;
 }
 
 int __setxid(int nr, int id, int eid, int sid)
 {
-       struct ctx c = { .nr = nr, .id = id, .eid = eid, .sid = sid };
-       switch (nr) {
-       case SYS_setuid:
-       case SYS_setreuid:
-       case SYS_setresuid:
-               c.rlim = 1;
-       }
+       /* ret is initially nonzero so that failure of the first thread does not
+        * trigger the safety kill above. */
+       struct ctx c = { .nr = nr, .id = id, .eid = eid, .sid = sid, .ret = 1 };
        __synccall(do_setxid, &c);
-       if (c.err) {
-               errno = c.err;
-               return -1;
-       }
-       return 0;
+       return __syscall_ret(c.ret);
 }