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authorSong Liu <songliubraving@fb.com>2019-05-07 09:15:45 -0700
committerIngo Molnar <mingo@kernel.org>2019-06-03 11:58:18 +0200
commit9fd2e48b9ae17978b2c2a98c055c774d5d90bce8 (patch)
tree1a19cedd49c777f1082315f48f6eabadfdf96b44 /kernel/events
parentf7b6a8b30cedaa64ba18d80f1fb3404274281639 (diff)
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perf/core: Allow non-privileged uprobe for user processes
Currently, non-privileged user could only use uprobe with kernel.perf_event_paranoid = -1 However, setting perf_event_paranoid to -1 leaks other users' processes to non-privileged uprobes. To introduce proper permission control of uprobes, we are building the following system: A daemon with CAP_SYS_ADMIN is in charge to create uprobes via tracefs; Users asks the daemon to create uprobes; Then user can attach uprobe only to processes owned by the user. This patch allows non-privileged user to attach uprobe to processes owned by the user. The following example shows how to use uprobe with non-privileged user. This is based on Brendan's blog post [1] 1. Create uprobe with root: sudo perf probe -x 'readline%return +0($retval):string' 2. Then non-root user can use the uprobe as: perf record -vvv -e probe_bash:readline__return -p <pid> sleep 20 perf script [1] http://www.brendangregg.com/blog/2015-06-28/linux-ftrace-uprobe.html Signed-off-by: Song Liu <songliubraving@fb.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: <kernel-team@fb.com> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/20190507161545.788381-1-songliubraving@fb.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/events')
-rw-r--r--kernel/events/core.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c
index abbd4b3b96c2..3005c80f621d 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -8532,9 +8532,9 @@ static int perf_tp_event_match(struct perf_event *event,
if (event->hw.state & PERF_HES_STOPPED)
return 0;
/*
- * All tracepoints are from kernel-space.
+ * If exclude_kernel, only trace user-space tracepoints (uprobes)
*/
- if (event->attr.exclude_kernel)
+ if (event->attr.exclude_kernel && !user_mode(regs))
return 0;
if (!perf_tp_filter_match(event, data))