From 1ccd15497869f3ed83b5225d410df53a96e52757 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Thu, 9 Apr 2009 10:53:45 +0200 Subject: [PATCH] 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 Cc: Paul Mackerras Cc: Corey Ashford LKML-Reference: <20090409085524.514046352@chello.nl> Signed-off-by: Ingo Molnar --- include/linux/perf_counter.h | 2 ++ kernel/perf_counter.c | 4 +++- kernel/sysctl.c | 11 +++++++++++ 3 files changed, 16 insertions(+), 1 deletion(-) diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h index c22363a4f746..981432885301 100644 --- a/include/linux/perf_counter.h +++ b/include/linux/perf_counter.h @@ -568,6 +568,8 @@ struct perf_callchain_entry { 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 76376ecb23b5..7efb7ebaaae0 100644 --- a/kernel/perf_counter.c +++ b/kernel/perf_counter.c @@ -42,6 +42,8 @@ static atomic_t nr_mmap_tracking __read_mostly; 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 @@ static struct perf_counter_context *find_get_context(pid_t pid, int cpu) */ 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 4286b62b34a0..8ba457838d95 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -49,6 +49,7 @@ #include #include #include +#include #include #include @@ -920,6 +921,16 @@ static struct ctl_table kern_table[] = { .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 -- GitLab