check the return value of setuid and friends

Under some circumstances, setuid() and family can fail,
returning a non-zero value.  (see "man setuid" for details).
If this happens, we want to ensure that init doesn't spawn a
process which has root privileges when it's not suppose to.

Change-Id: Idd03f2c8f82a7eaf6e696b5bcfe308e51ea58b52

1 files changed, 12 insertions, 3 deletions

diff --git a/init/init.c b/init/init.c
index cd129c3..7aef387 100755
--- a/init/init.c
+++ b/init/init.c
@@ -243,13 +243,22 @@ void service_start(struct service *svc, const char *dynamic_args)
 
     /* as requested, set our gid, supplemental gids, and uid */
         if (svc->gid) {
-            setgid(svc->gid);
+            if (setgid(svc->gid) != 0) {
+                ERROR("setgid failed: %s\n", strerror(errno));
+                _exit(127);
+            }
         }
         if (svc->nr_supp_gids) {
-            setgroups(svc->nr_supp_gids, svc->supp_gids);
+            if (setgroups(svc->nr_supp_gids, svc->supp_gids) != 0) {
+                ERROR("setgroups failed: %s\n", strerror(errno));
+                _exit(127);
+            }
         }
         if (svc->uid) {
-            setuid(svc->uid);
+            if (setuid(svc->uid) != 0) {
+                ERROR("setuid failed: %s\n", strerror(errno));
+                _exit(127);
+            }
         }
 
         if (!dynamic_args) {