[PATCH 3.5 60/78] perf/ftrace: Fix paranoid level for enabling function tracer

Luis Henriques luis.henriques at canonical.com
Mon Nov 25 13:06:47 UTC 2013 -stable review patch.  If anyone has any objections, please let me know.


From: Steven Rostedt <rostedt at goodmis.org>

commit 12ae030d54ef250706da5642fc7697cc60ad0df7 upstream.

The current default perf paranoid level is "1" which has
"perf_paranoid_kernel()" return false, and giving any operations that
use it, access to normal users. Unfortunately, this includes function
tracing and normal users should not be allowed to enable function
tracing by default.

The proper level is defined at "-1" (full perf access), which
"perf_paranoid_tracepoint_raw()" will only give access to. Use that
check instead for enabling function tracing.

Reported-by: Dave Jones <davej at redhat.com>
Reported-by: Vince Weaver <vincent.weaver at maine.edu>
Tested-by: Vince Weaver <vincent.weaver at maine.edu>
Cc: Peter Zijlstra <peterz at infradead.org>
Cc: Ingo Molnar <mingo at kernel.org>
Cc: Jiri Olsa <jolsa at redhat.com>
Cc: Frederic Weisbecker <fweisbec at gmail.com>
CVE: CVE-2013-2930
Fixes: ced39002f5ea ("ftrace, perf: Add support to use function tracepoint in perf")
Signed-off-by: Steven Rostedt <rostedt at goodmis.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
 kernel/trace/trace_event_perf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
index fee3752..d01adb7 100644
--- a/kernel/trace/trace_event_perf.c
+++ b/kernel/trace/trace_event_perf.c
@@ -26,7 +26,7 @@ static int perf_trace_event_perm(struct ftrace_event_call *tp_event,
 	/* The ftrace function trace is allowed only for root. */
 	if (ftrace_event_is_function(tp_event) &&
-	    perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))
+	    perf_paranoid_tracepoint_raw() && !capable(CAP_SYS_ADMIN))
 		return -EPERM;
 	/* No tracing, just counting, so no obvious leak */

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