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bpf: tracing: properly use bpf_prog_array api 

Now that we don't have __rcu markers on the bpf_prog_array helpers,
let's use proper rcu_dereference_protected to obtain array pointer
under mutex.

Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Stanislav Fomichev 2019-05-28 14:14:44 -07:00 committed by Daniel Borkmann
parent dbcc1ba26e
commit e672db03ab
1 changed files with 10 additions and 8 deletions
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18
kernel/trace/bpf_trace.c
View File

@ -19,6 +19,9 @@
#include "trace_probe.h"
#include "trace.h"
#define bpf_event_rcu_dereference(p) \
rcu_dereference_protected(p, lockdep_is_held(&bpf_event_mutex))
#ifdef CONFIG_MODULES
struct bpf_trace_module {
struct module *module;
@ -1099,7 +1102,7 @@ static DEFINE_MUTEX(bpf_event_mutex);
int perf_event_attach_bpf_prog(struct perf_event *event,
struct bpf_prog *prog)
{
struct bpf_prog_array __rcu *old_array;
struct bpf_prog_array *old_array;
struct bpf_prog_array *new_array;
int ret = -EEXIST;
@ -1117,7 +1120,7 @@ int perf_event_attach_bpf_prog(struct perf_event *event,
if (event->prog)
goto unlock;
old_array = event->tp_event->prog_array;
old_array = bpf_event_rcu_dereference(event->tp_event->prog_array);
if (old_array &&
bpf_prog_array_length(old_array) >= BPF_TRACE_MAX_PROGS) {
ret = -E2BIG;
@ -1140,7 +1143,7 @@ unlock:
void perf_event_detach_bpf_prog(struct perf_event *event)
{
struct bpf_prog_array __rcu *old_array;
struct bpf_prog_array *old_array;
struct bpf_prog_array *new_array;
int ret;
@ -1149,7 +1152,7 @@ void perf_event_detach_bpf_prog(struct perf_event *event)
if (!event->prog)
goto unlock;
old_array = event->tp_event->prog_array;
old_array = bpf_event_rcu_dereference(event->tp_event->prog_array);
ret = bpf_prog_array_copy(old_array, event->prog, NULL, &new_array);
if (ret == -ENOENT)
goto unlock;
@ -1171,6 +1174,7 @@ int perf_event_query_prog_array(struct perf_event *event, void __user *info)
{
struct perf_event_query_bpf __user *uquery = info;
struct perf_event_query_bpf query = {};
struct bpf_prog_array *progs;
u32 *ids, prog_cnt, ids_len;
int ret;
@ -1195,10 +1199,8 @@ int perf_event_query_prog_array(struct perf_event *event, void __user *info)
*/
mutex_lock(&bpf_event_mutex);
ret = bpf_prog_array_copy_info(event->tp_event->prog_array,
ids,
ids_len,
&prog_cnt);
progs = bpf_event_rcu_dereference(event->tp_event->prog_array);
ret = bpf_prog_array_copy_info(progs, ids, ids_len, &prog_cnt);
mutex_unlock(&bpf_event_mutex);
if (copy_to_user(&uquery->prog_cnt, &prog_cnt, sizeof(prog_cnt)) ||