tracing/filters: allow user-input to be integer-like string

Suppose we would like to trace all tasks named '123', but this
will fail:

 # echo 'parent_comm == 123' > events/sched/sched_process_fork/filter
 bash: echo: write error: Invalid argument

Don't guess the type of the filter pred in filter_parse(), but instead
we check it in __filter_add_pred().

[ Impact: extend allowed filter field string values ]

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <49ED8DEB.6000700@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 12 insertions, 14 deletions

diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index e0fcfd2a16d6..65418288f957 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -313,6 +313,7 @@ static int __filter_add_pred(struct ftrace_event_call *call,
 {
         struct ftrace_event_field *field;
         filter_pred_fn_t fn;
+        unsigned long long val;
 
         field = find_event_field(call, pred->field_name);
         if (!field)
@@ -322,14 +323,13 @@ static int __filter_add_pred(struct ftrace_event_call *call,
         pred->offset = field->offset;
 
         if (is_string_field(field->type)) {
-                if (!pred->str_len)
-                        return -EINVAL;
                 fn = filter_pred_string;
                 pred->str_len = field->size;
                 return filter_add_pred_fn(call, pred, fn);
         } else {
-                if (pred->str_len)
+                if (strict_strtoull(pred->str_val, 0, &val))
                         return -EINVAL;
+                pred->val = val;
         }
 
         switch (field->size) {
@@ -413,12 +413,16 @@ int filter_add_subsystem_pred(struct event_subsystem *system,
         return 0;
 }
 
+/*
+ * The filter format can be
+ *   - 0, which means remove all filter preds
+ *   - [||/&&] <field> ==/!= <val>
+ */
 int filter_parse(char **pbuf, struct filter_pred *pred)
 {
-        char *tmp, *tok, *val_str = NULL;
+        char *tok, *val_str = NULL;
         int tok_n = 0;
 
-        /* field ==/!= number, or/and field ==/!= number, number */
         while ((tok = strsep(pbuf, " \n"))) {
                 if (tok_n == 0) {
                         if (!strcmp(tok, "0")) {
@@ -478,19 +482,13 @@ int filter_parse(char **pbuf, struct filter_pred *pred)
                 return -EINVAL;
         }
 
+        strcpy(pred->str_val, val_str);
+        pred->str_len = strlen(val_str);
+
         pred->field_name = kstrdup(pred->field_name, GFP_KERNEL);
         if (!pred->field_name)
                 return -ENOMEM;
 
-        pred->str_len = 0;
-        pred->val = simple_strtoull(val_str, &tmp, 0);
-        if (tmp == val_str) {
-                strncpy(pred->str_val, val_str, MAX_FILTER_STR_VAL);
-                pred->str_len = strlen(val_str);
-                pred->str_val[pred->str_len] = '\0';
-        } else if (*tmp != '\0')
-                return -EINVAL;
-
         return 0;
 }