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authorMatt Mackall <mpm@selenic.com>2005-05-01 08:59:00 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-05-01 08:59:00 -0700
commite43379f10b42194b8a6e1de342cfb44463c0f6da (patch)
treebf6463200dc7e14f266b7f12807c7cbfbb6700c2
parent9fc1427a01a9df3605e219c6de0c59c4639209a1 (diff)
[PATCH] nice and rt-prio rlimits
Add a pair of rlimits for allowing non-root tasks to raise nice and rt priorities. Defaults to traditional behavior. Originally written by Chris Wright. The patch implements a simple rlimit ceiling for the RT (and nice) priorities a task can set. The rlimit defaults to 0, meaning no change in behavior by default. A value of 50 means RT priority levels 1-50 are allowed. A value of 100 means all 99 privilege levels from 1 to 99 are allowed. CAP_SYS_NICE is blanket permission. (akpm: see http://www.uwsg.iu.edu/hypermail/linux/kernel/0503.1/1921.html for tips on integrating this with PAM). Signed-off-by: Matt Mackall <mpm@selenic.com> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--include/asm-generic/resource.h7
-rw-r--r--include/linux/sched.h1
-rw-r--r--kernel/sched.c25
-rw-r--r--kernel/sys.c2
4 files changed, 27 insertions, 8 deletions
diff --git a/include/asm-generic/resource.h b/include/asm-generic/resource.h
index b1fcda9eac23..cfe3692b23e5 100644
--- a/include/asm-generic/resource.h
+++ b/include/asm-generic/resource.h
@@ -41,8 +41,11 @@
#define RLIMIT_LOCKS 10 /* maximum file locks held */
#define RLIMIT_SIGPENDING 11 /* max number of pending signals */
#define RLIMIT_MSGQUEUE 12 /* maximum bytes in POSIX mqueues */
+#define RLIMIT_NICE 13 /* max nice prio allowed to raise to
+ 0-39 for nice level 19 .. -20 */
+#define RLIMIT_RTPRIO 14 /* maximum realtime priority */
-#define RLIM_NLIMITS 13
+#define RLIM_NLIMITS 15
/*
* SuS says limits have to be unsigned.
@@ -81,6 +84,8 @@
[RLIMIT_LOCKS] = { RLIM_INFINITY, RLIM_INFINITY }, \
[RLIMIT_SIGPENDING] = { 0, 0 }, \
[RLIMIT_MSGQUEUE] = { MQ_BYTES_MAX, MQ_BYTES_MAX }, \
+ [RLIMIT_NICE] = { 0, 0 }, \
+ [RLIMIT_RTPRIO] = { 0, 0 }, \
}
#endif /* __KERNEL__ */
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 1cced971232c..8960f99ea128 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -845,6 +845,7 @@ extern void sched_idle_next(void);
extern void set_user_nice(task_t *p, long nice);
extern int task_prio(const task_t *p);
extern int task_nice(const task_t *p);
+extern int can_nice(const task_t *p, const int nice);
extern int task_curr(const task_t *p);
extern int idle_cpu(int cpu);
extern int sched_setscheduler(struct task_struct *, int, struct sched_param *);
diff --git a/kernel/sched.c b/kernel/sched.c
index 9bb7489ee645..5dadcc6df7dd 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -3223,6 +3223,19 @@ out_unlock:
EXPORT_SYMBOL(set_user_nice);
+/*
+ * can_nice - check if a task can reduce its nice value
+ * @p: task
+ * @nice: nice value
+ */
+int can_nice(const task_t *p, const int nice)
+{
+ /* convert nice value [19,-20] to rlimit style value [0,39] */
+ int nice_rlim = 19 - nice;
+ return (nice_rlim <= p->signal->rlim[RLIMIT_NICE].rlim_cur ||
+ capable(CAP_SYS_NICE));
+}
+
#ifdef __ARCH_WANT_SYS_NICE
/*
@@ -3242,12 +3255,8 @@ asmlinkage long sys_nice(int increment)
* We don't have to worry. Conceptually one call occurs first
* and we have a single winner.
*/
- if (increment < 0) {
- if (!capable(CAP_SYS_NICE))
- return -EPERM;
- if (increment < -40)
- increment = -40;
- }
+ if (increment < -40)
+ increment = -40;
if (increment > 40)
increment = 40;
@@ -3257,6 +3266,9 @@ asmlinkage long sys_nice(int increment)
if (nice > 19)
nice = 19;
+ if (increment < 0 && !can_nice(current, nice))
+ return -EPERM;
+
retval = security_task_setnice(current, nice);
if (retval)
return retval;
@@ -3372,6 +3384,7 @@ recheck:
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) &&
diff --git a/kernel/sys.c b/kernel/sys.c
index df2ddcc6863b..7f43d6e62c7a 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -227,7 +227,7 @@ static int set_one_prio(struct task_struct *p, int niceval, int error)
error = -EPERM;
goto out;
}
- if (niceval < task_nice(p) && !capable(CAP_SYS_NICE)) {
+ if (niceval < task_nice(p) && !can_nice(p, niceval)) {
error = -EACCES;
goto out;
}