From cfa77bc4af2c75c0781ee76cde2dd104c6c8e2b7 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Sun, 2 Mar 2014 16:56:38 +0100 Subject: perf: Disallow user-space callchains for function trace events Recent issues with user space callchains processing within page fault handler tracing showed as Peter said 'there's just too much fail surface'. Related list discussions: http://marc.info/?t=139302086500001&r=1&w=2 http://marc.info/?t=139301437300003&r=1&w=2 Suggested-by: Peter Zijlstra Signed-off-by: Jiri Olsa Cc: Paul Mackerras Cc: Arnaldo Carvalho de Melo Cc: "H. Peter Anvin" Cc: Vince Weaver Cc: Steven Rostedt Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/1393775800-13524-2-git-send-email-jolsa@redhat.com Signed-off-by: Ingo Molnar --- kernel/trace/trace_event_perf.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) (limited to 'kernel/trace') diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c index e854f420e033..d5e01c3f4e69 100644 --- a/kernel/trace/trace_event_perf.c +++ b/kernel/trace/trace_event_perf.c @@ -31,9 +31,18 @@ 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_tracepoint_raw() && !capable(CAP_SYS_ADMIN)) - return -EPERM; + if (ftrace_event_is_function(tp_event)) { + if (perf_paranoid_tracepoint_raw() && !capable(CAP_SYS_ADMIN)) + return -EPERM; + + /* + * We don't allow user space callchains for function trace + * event, due to issues with page faults while tracing page + * fault handler and its overall trickiness nature. + */ + if (!p_event->attr.exclude_callchain_user) + return -EINVAL; + } /* No tracing, just counting, so no obvious leak */ if (!(p_event->attr.sample_type & PERF_SAMPLE_RAW)) -- cgit v1.2.3 From 63c45f4ba533e9749da16298db53e491c25d805b Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Sun, 2 Mar 2014 16:56:39 +0100 Subject: perf: Disallow user-space stack dumps for function trace events Recent issues with user space callchains processing within page fault handler tracing showed as Peter said 'there's just too much fail surface'. The user space stack dump is just another source of the this issue. Related list discussions: http://marc.info/?t=139302086500001&r=1&w=2 http://marc.info/?t=139301437300003&r=1&w=2 Suggested-by: Peter Zijlstra Signed-off-by: Jiri Olsa Cc: Paul Mackerras Cc: Arnaldo Carvalho de Melo Cc: Vince Weaver Cc: Steven Rostedt Cc: Paul Mackerras Cc: H. Peter Anvin Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/1393775800-13524-3-git-send-email-jolsa@redhat.com Signed-off-by: Ingo Molnar --- kernel/trace/trace_event_perf.c | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'kernel/trace') diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c index d5e01c3f4e69..c894614de14d 100644 --- a/kernel/trace/trace_event_perf.c +++ b/kernel/trace/trace_event_perf.c @@ -42,6 +42,13 @@ static int perf_trace_event_perm(struct ftrace_event_call *tp_event, */ if (!p_event->attr.exclude_callchain_user) return -EINVAL; + + /* + * Same reason to disable user stack dump as for user space + * callchains above. + */ + if (p_event->attr.sample_type & PERF_SAMPLE_STACK_USER) + return -EINVAL; } /* No tracing, just counting, so no obvious leak */ -- cgit v1.2.3