prctl: adds the capable(CAP_SYS_NICE) check to PR_SET_TIMERSLACK_PID.

Adds a capable() check to make sure that arbitary apps do not change the
timer slack for other apps.

Bug: 15000427
Change-Id: I558a2551a0e3579c7f7e7aae54b28aa9d982b209
Signed-off-by: Ruchi Kandoi <kandoiruchi@google.com>

diff --git a/kernel/sys.c b/kernel/sys.c
index 875529e936abae09b01082555edd9357a6001507..ab7fda5fbe188559fcb7924fa5944e8439c8e856 100644 (file)
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -2378,6 +2378,9 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
                                return -EINVAL;
                        break;
                case PR_SET_TIMERSLACK_PID:
+                       if (current->pid != (pid_t)arg3 &&
+                                       !capable(CAP_SYS_NICE))
+                               return -EPERM;
                        rcu_read_lock();
                        tsk = find_task_by_pid_ns((pid_t)arg3, &init_pid_ns);
                        if (tsk == NULL) {