[PATCH] Changing RT priority without CAP_SYS_NICE

[karo-tx-linux.git] / kernel / sched.c

diff --git a/kernel/sched.c b/kernel/sched.c
index a3d1c8e43d3481a785470eb226326ce097ec0f72..d3d81b82e3784e52befe9199f008e5fa8d9809b2 100644 (file)
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -3531,13 +3531,24 @@ recheck:
        if ((policy == SCHED_NORMAL) != (param->sched_priority == 0))
                return -EINVAL;
 
-       if ((policy == SCHED_FIFO || policy == SCHED_RR) &&
-           param->sched_priority > p->signal->rlim[RLIMIT_RTPRIO].rlim_cur &&
-           !capable(CAP_SYS_NICE))
-               return -EPERM;
-       if ((current->euid != p->euid) && (current->euid != p->uid) &&
-           !capable(CAP_SYS_NICE))
-               return -EPERM;
+       /*
+        * Allow unprivileged RT tasks to decrease priority:
+        */
+       if (!capable(CAP_SYS_NICE)) {
+               /* can't change policy */
+               if (policy != p->policy)
+                       return -EPERM;
+               /* can't increase priority */
+               if (policy != SCHED_NORMAL &&
+                   param->sched_priority > p->rt_priority &&
+                   param->sched_priority >
+                               p->signal->rlim[RLIMIT_RTPRIO].rlim_cur)
+                       return -EPERM;
+               /* can't change other user's priorities */
+               if ((current->euid != p->euid) &&
+                   (current->euid != p->uid))
+                       return -EPERM;
+       }
 
        retval = security_task_setscheduler(p, policy, param);
        if (retval)