Re: [PATCH]sched: Isochronous class v2 for unprivileged soft rt scheduling
From: Chris Wright
Date: Sat Jan 22 2005 - 22:02:28 EST
* Nick Piggin (nickpiggin@xxxxxxxxxxxx) wrote:
> Jack O'Quin wrote:
>
> > Chris Wright and Arjan van de Ven have outlined a proposal to address
> > the privilege issue using rlimits. This is still the only workable
> > alternative to the realtime LSM on the table. If the decision were up
> > to me, I would choose the simplicity and better security of the LSM.
> > But their approach is adequate, if implemented in a timely fashion. I
> > would like to see some progress on this in addition to the scheduler
> > work. People still need SCHED_FIFO for some applications.
> >
>
> I think this is a pretty sane and minimally intrusive (for the kernel)
> way to support what you want.
Here's an untested respin against current bk.
thanks,
-chris
===== include/asm-generic/resource.h 1.1 vs edited =====
--- 1.1/include/asm-generic/resource.h 2005-01-20 21:00:51 -08:00
+++ edited/include/asm-generic/resource.h 2005-01-22 18:54:58 -08:00
@@ -20,8 +20,11 @@
#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 RLIM_NLIMITS 13
+#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 15
#endif
/*
@@ -53,6 +56,8 @@
[RLIMIT_LOCKS] = { RLIM_INFINITY, RLIM_INFINITY }, \
[RLIMIT_SIGPENDING] = { MAX_SIGPENDING, MAX_SIGPENDING }, \
[RLIMIT_MSGQUEUE] = { MQ_BYTES_MAX, MQ_BYTES_MAX }, \
+ [RLIMIT_NICE] = { 0, 0 }, \
+ [RLIMIT_RTPRIO] = { 0, 0 }, \
}
#endif /* __KERNEL__ */
===== include/asm-alpha/resource.h 1.6 vs edited =====
--- 1.6/include/asm-alpha/resource.h 2005-01-20 21:00:50 -08:00
+++ edited/include/asm-alpha/resource.h 2005-01-22 18:58:04 -08:00
@@ -18,8 +18,11 @@
#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 RLIM_NLIMITS 13
+#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 15
#define __ARCH_RLIMIT_ORDER
/*
===== include/asm-mips/resource.h 1.8 vs edited =====
--- 1.8/include/asm-mips/resource.h 2005-01-20 21:00:50 -08:00
+++ edited/include/asm-mips/resource.h 2005-01-22 18:59:29 -08:00
@@ -25,8 +25,11 @@
#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 /* Number of limit flavors. */
+#define RLIM_NLIMITS 15 /* Number of limit flavors. */
#define __ARCH_RLIMIT_ORDER
/*
===== include/asm-sparc/resource.h 1.6 vs edited =====
--- 1.6/include/asm-sparc/resource.h 2005-01-20 21:00:50 -08:00
+++ edited/include/asm-sparc/resource.h 2005-01-22 19:00:07 -08:00
@@ -24,8 +24,11 @@
#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
#define __ARCH_RLIMIT_ORDER
/*
===== include/asm-sparc64/resource.h 1.6 vs edited =====
--- 1.6/include/asm-sparc64/resource.h 2005-01-20 21:00:50 -08:00
+++ edited/include/asm-sparc64/resource.h 2005-01-22 19:00:41 -08:00
@@ -24,8 +24,11 @@
#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
#define __ARCH_RLIMIT_ORDER
#include <asm-generic/resource.h>
===== include/linux/sched.h 1.274 vs edited =====
--- 1.274/include/linux/sched.h 2005-01-18 12:27:58 -08:00
+++ edited/include/linux/sched.h 2005-01-22 18:52:07 -08:00
@@ -767,6 +767,7 @@ 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 *);
===== kernel/sched.c 1.387 vs edited =====
--- 1.387/kernel/sched.c 2005-01-20 16:00:00 -08:00
+++ edited/kernel/sched.c 2005-01-22 18:52:07 -08:00
@@ -3220,6 +3220,19 @@ 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
/*
@@ -3239,12 +3252,8 @@ 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;
@@ -3254,6 +3263,9 @@ 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;
@@ -3369,6 +3381,7 @@ 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) &&
===== kernel/sys.c 1.104 vs edited =====
--- 1.104/kernel/sys.c 2005-01-11 16:42:35 -08:00
+++ edited/kernel/sys.c 2005-01-22 18:52:07 -08:00
@@ -225,7 +225,7 @@ static int set_one_prio(struct task_stru
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;
}
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/