perf_counter: sysctl for system wide perf counters
Impact: add sysctl for paranoid/relaxed perfcounters policy
Allow the use of system wide perf counters to everybody, but provide
a sysctl to disable it for the paranoid security minded.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090409085524.514046352@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h
index c22363a..9814328 100644
--- a/include/linux/perf_counter.h
+++ b/include/linux/perf_counter.h
@@ -568,6 +568,8 @@
extern struct perf_callchain_entry *perf_callchain(struct pt_regs *regs);
+extern int sysctl_perf_counter_priv;
+
#else
static inline void
perf_counter_task_sched_in(struct task_struct *task, int cpu) { }
diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index 76376ec..7efb7eb 100644
--- a/kernel/perf_counter.c
+++ b/kernel/perf_counter.c
@@ -42,6 +42,8 @@
static atomic_t nr_munmap_tracking __read_mostly;
static atomic_t nr_comm_tracking __read_mostly;
+int sysctl_perf_counter_priv __read_mostly; /* do we need to be privileged */
+
/*
* Mutex for (sysadmin-configurable) counter reservations:
*/
@@ -1132,7 +1134,7 @@
*/
if (cpu != -1) {
/* Must be root to operate on a CPU counter: */
- if (!capable(CAP_SYS_ADMIN))
+ if (sysctl_perf_counter_priv && !capable(CAP_SYS_ADMIN))
return ERR_PTR(-EACCES);
if (cpu < 0 || cpu > num_possible_cpus())
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 4286b62..8ba4578 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -49,6 +49,7 @@
#include <linux/reboot.h>
#include <linux/ftrace.h>
#include <linux/slow-work.h>
+#include <linux/perf_counter.h>
#include <asm/uaccess.h>
#include <asm/processor.h>
@@ -920,6 +921,16 @@
.child = slow_work_sysctls,
},
#endif
+#ifdef CONFIG_PERF_COUNTERS
+ {
+ .ctl_name = CTL_UNNUMBERED,
+ .procname = "perf_counter_privileged",
+ .data = &sysctl_perf_counter_priv,
+ .maxlen = sizeof(sysctl_perf_counter_priv),
+ .mode = 0644,
+ .proc_handler = &proc_dointvec,
+ },
+#endif
/*
* NOTE: do not add new entries to this table unless you have read
* Documentation/sysctl/ctl_unnumbered.txt