groups: Consolidate the setgroups permission checks
Today there are 3 instances of setgroups and due to an oversight their
permission checking has diverged. Add a common function so that
they may all share the same permission checking code.
This corrects the current oversight in the current permission checks
and adds a helper to avoid this in the future.
A user namespace security fix will update this new helper, shortly.
Cc: stable@vger.kernel.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
diff --git a/kernel/groups.c b/kernel/groups.c
index 451698f..02d8a25 100644
--- a/kernel/groups.c
+++ b/kernel/groups.c
@@ -213,6 +213,13 @@
return i;
}
+bool may_setgroups(void)
+{
+ struct user_namespace *user_ns = current_user_ns();
+
+ return ns_capable(user_ns, CAP_SETGID);
+}
+
/*
* SMP: Our groups are copy-on-write. We can set them safely
* without another task interfering.
@@ -223,7 +230,7 @@
struct group_info *group_info;
int retval;
- if (!ns_capable(current_user_ns(), CAP_SETGID))
+ if (!may_setgroups())
return -EPERM;
if ((unsigned)gidsetsize > NGROUPS_MAX)
return -EINVAL;