userns: user namespaces: convert several capable() calls

CAP_IPC_OWNER and CAP_IPC_LOCK can be checked against current_user_ns(),
because the resource comes from current's own ipc namespace.

setuid/setgid are to uids in own namespace, so again checks can be against
current_user_ns().

Changelog:
	Jan 11: Use task_ns_capable() in place of sched_capable().
	Jan 11: Use nsown_capable() as suggested by Bastian Blank.
	Jan 11: Clarify (hopefully) some logic in futex and sched.c
	Feb 15: use ns_capable for ipc, not nsown_capable
	Feb 23: let copy_ipcs handle setting ipc_ns->user_ns
	Feb 23: pass ns down rather than taking it from current

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Daniel Lezcano <daniel.lezcano@free.fr>
Acked-by: David Howells <dhowells@redhat.com>
Cc: James Morris <jmorris@namei.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 3 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index a172494a9a63..480adeb63f8f 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -4892,8 +4892,11 @@ static bool check_same_owner(struct task_struct *p)
 
         rcu_read_lock();
         pcred = __task_cred(p);
-        match = (cred->euid == pcred->euid ||
-                 cred->euid == pcred->uid);
+        if (cred->user->user_ns == pcred->user->user_ns)
+                match = (cred->euid == pcred->euid ||
+                         cred->euid == pcred->uid);
+        else
+                match = false;
         rcu_read_unlock();
         return match;
 }
@@ -5221,7 +5224,7 @@ long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
                 goto out_free_cpus_allowed;
         }
         retval = -EPERM;
-        if (!check_same_owner(p) && !capable(CAP_SYS_NICE))
+        if (!check_same_owner(p) && !task_ns_capable(p, CAP_SYS_NICE))
                 goto out_unlock;
 
         retval = security_task_setscheduler(p);