[PATCH 1/1] tracing: Require tracepoint permission for perf function filters
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COOLING9d
From: Zhengchuan Liang <hidden>
Date: 2026-09-28 00:00:56
Also in:
linux-perf-users, lkml, stable
Subsystem:
the rest, tracing · Maintainers:
Linus Torvalds, Steven Rostedt, Masami Hiramatsu
Count-only perf tracepoint events can be opened without tracepoint
permission because they do not sample raw event data. Their SET_FILTER
ioctl still parses .function predicates. Numeric operands call
kallsyms_lookup_size_offset(), making ioctl success an oracle for
recovering the randomized kernel text base. Symbolic operands resolve
hidden symbol addresses and can also match user-controlled event fields
against those addresses.
Pass the perf origin through filter parsing and require
perf_allow_tracepoint() before resolving either form of .function
operand. Ordinary perf count filters and tracefs event filters retain
their existing behavior.
Fixes: e6745a4da964 ("tracing: Add a way to filter function addresses to function names")
Cc: stable@vger.kernel.org
Assisted-by: LLM
Signed-off-by: Zhengchuan Liang <redacted>
---
kernel/trace/trace_events_filter.c | 39 ++++++++++++++++++++++--------
1 file changed, 29 insertions(+), 10 deletions(-)
diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index 2b46ca536045..f99b0f1e32d8 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c@@ -1625,12 +1625,18 @@ static int filter_pred_fn_call(struct filter_pred *pred, void *event) } } +struct event_filter_parse_data { + struct trace_event_call *call; + bool from_perf; +}; + /* Called when a predicate is encountered by predicate_parse() */ static int parse_pred(const char *str, void *data, int pos, struct filter_parse_error *pe, struct filter_pred **pred_ptr) { - struct trace_event_call *call = data; + struct event_filter_parse_data *parse_data = data; + struct trace_event_call *call = parse_data->call; struct ftrace_event_field *field; struct filter_pred *pred = NULL; unsigned long offset;
@@ -1686,6 +1692,12 @@ static int parse_pred(const char *str, void *data, function = true; i += len; } + if (function && parse_data->from_perf) { + /* Both numeric and symbolic operands resolve kernel addresses. */ + ret = perf_allow_tracepoint(); + if (ret) + return ret; + } while (isspace(str[i])) i++;
@@ -2205,8 +2217,13 @@ static int calc_stack(const char *str, int *parens, int *preds, int *err) static int process_preds(struct trace_event_call *call, const char *filter_string, struct event_filter *filter, - struct filter_parse_error *pe) + struct filter_parse_error *pe, + bool from_perf) { + struct event_filter_parse_data data = { + .call = call, + .from_perf = from_perf, + }; struct prog_entry *prog; int nr_parens; int nr_preds;
@@ -2232,7 +2249,7 @@ static int process_preds(struct trace_event_call *call, return -EINVAL; prog = predicate_parse(filter_string, nr_parens, nr_preds, - parse_pred, call, pe); + parse_pred, &data, pe); if (IS_ERR(prog)) return PTR_ERR(prog);
@@ -2281,7 +2298,8 @@ static int process_system_preds(struct trace_subsystem_dir *dir, if (!filter->filter_string) goto fail_mem; - err = process_preds(file->event_call, filter_string, filter, pe); + err = process_preds(file->event_call, filter_string, filter, pe, + false); if (err) { filter_disable(file); parse_error(pe, FILT_ERR_BAD_SUBSYS_FILTER, 0);
@@ -2377,6 +2395,7 @@ static void create_filter_finish(struct filter_parse_error *pe) * @call: trace_event_call to create a filter for * @filter_string: filter string * @set_str: remember @filter_str and enable detailed error in filter + * @from_perf: require tracepoint permission for function predicates * @filterp: out param for created filter (always updated on return) * Must be a pointer that references a NULL pointer. *
@@ -2391,7 +2410,7 @@ static void create_filter_finish(struct filter_parse_error *pe) */ static int create_filter(struct trace_array *tr, struct trace_event_call *call, - char *filter_string, bool set_str, + char *filter_string, bool set_str, bool from_perf, struct event_filter **filterp) { struct filter_parse_error *pe = NULL;
@@ -2405,7 +2424,7 @@ static int create_filter(struct trace_array *tr, if (err) return err; - err = process_preds(call, filter_string, *filterp, pe); + err = process_preds(call, filter_string, *filterp, pe, from_perf); if (err && set_str) append_filter_err(tr, pe, *filterp); create_filter_finish(pe);
@@ -2418,7 +2437,7 @@ int create_event_filter(struct trace_array *tr, char *filter_str, bool set_str, struct event_filter **filterp) { - return create_filter(tr, call, filter_str, set_str, filterp); + return create_filter(tr, call, filter_str, set_str, false, filterp); } /**
@@ -2476,7 +2495,7 @@ int apply_event_filter(struct trace_event_file *file, char *filter_string) return 0; } - err = create_filter(file->tr, call, filter_string, true, &filter); + err = create_filter(file->tr, call, filter_string, true, false, &filter); /* * Always swap the call filter with the new filter
@@ -2721,7 +2740,7 @@ int ftrace_profile_set_filter(struct perf_event *event, int event_id, if (event->filter) return -EEXIST; - err = create_filter(NULL, call, filter_str, false, &filter); + err = create_filter(NULL, call, filter_str, false, true, &filter); if (err) goto free_filter;
@@ -2868,7 +2887,7 @@ static __init int ftrace_test_event_filter(void) int err; err = create_filter(NULL, &event_ftrace_test_filter, - d->filter, false, &filter); + d->filter, false, false, &filter); if (err) { printk(KERN_INFO "Failed to get filter for '%s', err %d\n",
--
2.34.1