From 9fd2e48b9ae17978b2c2a98c055c774d5d90bce8 Mon Sep 17 00:00:00 2001 From: Song Liu Date: Tue, 7 May 2019 09:15:45 -0700 Subject: [PATCH] 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 sleep 20 perf script [1] http://www.brendangregg.com/blog/2015-06-28/linux-ftrace-uprobe.html Signed-off-by: Song Liu Signed-off-by: Peter Zijlstra (Intel) Cc: Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: https://lkml.kernel.org/r/20190507161545.788381-1-songliubraving@fb.com Signed-off-by: Ingo Molnar --- kernel/events/core.c | 4 ++-- kernel/trace/trace_uprobe.c | 2 +- 2 files changed, 3 insertions(+), 3 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)) diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c index eb7e06b54741..0d60d6856de5 100644 --- a/kernel/trace/trace_uprobe.c +++ b/kernel/trace/trace_uprobe.c @@ -1331,7 +1331,7 @@ static inline void init_trace_event_call(struct trace_uprobe *tu, call->event.funcs = &uprobe_funcs; call->class->define_fields = uprobe_event_define_fields; - call->flags = TRACE_EVENT_FL_UPROBE; + call->flags = TRACE_EVENT_FL_UPROBE | TRACE_EVENT_FL_CAP_ANY; call->class->reg = trace_uprobe_register; call->data = tu; }