tracing/probes: Reject events which have the same name of existing one

[ Upstream commit 8e242060c6a4947e8ae7d29794af6a581db08841 ]

Since kprobe_events and uprobe_events only check whether the
other same-type probe event has the same name or not, if the
user gives the same name of the existing tracepoint event (or
the other type of probe events), it silently fails to create
the tracefs entry (but registered.) as below.

/sys/kernel/tracing # ls events/task/task_rename
enable   filter   format   hist     id       trigger
/sys/kernel/tracing # echo p:task/task_rename vfs_read >> kprobe_events
[  113.048508] Could not create tracefs 'task_rename' directory
/sys/kernel/tracing # cat kprobe_events
p:task/task_rename vfs_read

To fix this issue, check whether the existing events have the
same name or not in trace_probe_register_event_call(). If exists,
it rejects to register the new event.

Link: https://lkml.kernel.org/r/162936876189.187130.17558311387542061930.stgit@devnote2
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index ea6178cb5e334dbd346519f5405b0a0dc671dd79..032191977e34c080aec4b6e7c0dd479783f762a3 100644 (file)
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -647,7 +647,11 @@ static int register_trace_kprobe(struct trace_kprobe *tk)
        /* Register new event */
        ret = register_kprobe_event(tk);
        if (ret) {
-               pr_warn("Failed to register probe event(%d)\n", ret);
+               if (ret == -EEXIST) {
+                       trace_probe_log_set_index(0);
+                       trace_probe_log_err(0, EVENT_EXIST);
+               } else
+                       pr_warn("Failed to register probe event(%d)\n", ret);
                goto end;
        }
 

diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index 15413ad7cef2bdba2d9a306c099caffd2431426d..0e29bb14fc8be192cbc5835099c99e3a7e6cde79 100644 (file)
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -1029,11 +1029,36 @@ error:
        return ret;
 }
 
+static struct trace_event_call *
+find_trace_event_call(const char *system, const char *event_name)
+{
+       struct trace_event_call *tp_event;
+       const char *name;
+
+       list_for_each_entry(tp_event, &ftrace_events, list) {
+               if (!tp_event->class->system ||
+                   strcmp(system, tp_event->class->system))
+                       continue;
+               name = trace_event_name(tp_event);
+               if (!name || strcmp(event_name, name))
+                       continue;
+               return tp_event;
+       }
+
+       return NULL;
+}
+
 int trace_probe_register_event_call(struct trace_probe *tp)
 {
        struct trace_event_call *call = trace_probe_event_call(tp);
        int ret;
 
+       lockdep_assert_held(&event_mutex);
+
+       if (find_trace_event_call(trace_probe_group_name(tp),
+                                 trace_probe_name(tp)))
+               return -EEXIST;
+
        ret = register_trace_event(&call->event);
        if (!ret)
                return -ENODEV;

diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
index 227d518e5ba521f1ef0914c44f099e76c8b1f5d7..9f14186d132ed221bd8396f0cfe502b459cace57 100644 (file)
--- a/kernel/trace/trace_probe.h
+++ b/kernel/trace/trace_probe.h
@@ -399,6 +399,7 @@ extern int traceprobe_define_arg_fields(struct trace_event_call *event_call,
        C(NO_EVENT_NAME,        "Event name is not specified"),         \
        C(EVENT_TOO_LONG,       "Event name is too long"),              \
        C(BAD_EVENT_NAME,       "Event name must follow the same rules as C identifiers"), \
+       C(EVENT_EXIST,          "Given group/event name is already used by another event"), \
        C(RETVAL_ON_PROBE,      "$retval is not available on probe"),   \
        C(BAD_STACK_NUM,        "Invalid stack number"),                \
        C(BAD_ARG_NUM,          "Invalid argument number"),             \

diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index 9b50869a5ddb5dc51ca9ebe12e33ac3a1e22fe7f..957244ee07c8d0682e862d17f9d0a4317e3246ea 100644 (file)
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -514,7 +514,11 @@ static int register_trace_uprobe(struct trace_uprobe *tu)
 
        ret = register_uprobe_event(tu);
        if (ret) {
-               pr_warn("Failed to register probe event(%d)\n", ret);
+               if (ret == -EEXIST) {
+                       trace_probe_log_set_index(0);
+                       trace_probe_log_err(0, EVENT_EXIST);
+               } else
+                       pr_warn("Failed to register probe event(%d)\n", ret);
                goto end;
        }