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authorAlexei Starovoitov <ast@fb.com>2016-04-27 18:56:21 -0700
committerDavid S. Miller <davem@davemloft.net>2016-04-28 17:29:45 -0400
commit6aff67c85c9e5a4bc99e5211c1bac547936626ca (patch)
tree3be9fa8e180334d6f8e0c5edb5e47f8113f4b2f4 /kernel/bpf
parent92117d8443bc5afacc8d5ba82e541946310f106e (diff)
downloadlinux-sh-6aff67c85c9e5a4bc99e5211c1bac547936626ca.tar.gz
bpf: fix check_map_func_compatibility logic
The commit 35578d798400 ("bpf: Implement function bpf_perf_event_read() that get the selected hardware PMU conuter") introduced clever way to check bpf_helper<->map_type compatibility. Later on commit a43eec304259 ("bpf: introduce bpf_perf_event_output() helper") adjusted the logic and inadvertently broke it. Get rid of the clever bool compare and go back to two-way check from map and from helper perspective. Fixes: a43eec304259 ("bpf: introduce bpf_perf_event_output() helper") Reported-by: Jann Horn <jannh@google.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'kernel/bpf')
-rw-r--r--kernel/bpf/verifier.c65
1 files changed, 40 insertions, 25 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 89bcaa0966da..c5c17a62f509 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -239,16 +239,6 @@ static const char * const reg_type_str[] = {
[CONST_IMM] = "imm",
};
-static const struct {
- int map_type;
- int func_id;
-} func_limit[] = {
- {BPF_MAP_TYPE_PROG_ARRAY, BPF_FUNC_tail_call},
- {BPF_MAP_TYPE_PERF_EVENT_ARRAY, BPF_FUNC_perf_event_read},
- {BPF_MAP_TYPE_PERF_EVENT_ARRAY, BPF_FUNC_perf_event_output},
- {BPF_MAP_TYPE_STACK_TRACE, BPF_FUNC_get_stackid},
-};
-
static void print_verifier_state(struct verifier_env *env)
{
enum bpf_reg_type t;
@@ -921,27 +911,52 @@ static int check_func_arg(struct verifier_env *env, u32 regno,
static int check_map_func_compatibility(struct bpf_map *map, int func_id)
{
- bool bool_map, bool_func;
- int i;
-
if (!map)
return 0;
- for (i = 0; i < ARRAY_SIZE(func_limit); i++) {
- bool_map = (map->map_type == func_limit[i].map_type);
- bool_func = (func_id == func_limit[i].func_id);
- /* only when map & func pair match it can continue.
- * don't allow any other map type to be passed into
- * the special func;
- */
- if (bool_func && bool_map != bool_func) {
- verbose("cannot pass map_type %d into func %d\n",
- map->map_type, func_id);
- return -EINVAL;
- }
+ /* We need a two way check, first is from map perspective ... */
+ switch (map->map_type) {
+ case BPF_MAP_TYPE_PROG_ARRAY:
+ if (func_id != BPF_FUNC_tail_call)
+ goto error;
+ break;
+ case BPF_MAP_TYPE_PERF_EVENT_ARRAY:
+ if (func_id != BPF_FUNC_perf_event_read &&
+ func_id != BPF_FUNC_perf_event_output)
+ goto error;
+ break;
+ case BPF_MAP_TYPE_STACK_TRACE:
+ if (func_id != BPF_FUNC_get_stackid)
+ goto error;
+ break;
+ default:
+ break;
+ }
+
+ /* ... and second from the function itself. */
+ switch (func_id) {
+ case BPF_FUNC_tail_call:
+ if (map->map_type != BPF_MAP_TYPE_PROG_ARRAY)
+ goto error;
+ break;
+ case BPF_FUNC_perf_event_read:
+ case BPF_FUNC_perf_event_output:
+ if (map->map_type != BPF_MAP_TYPE_PERF_EVENT_ARRAY)
+ goto error;
+ break;
+ case BPF_FUNC_get_stackid:
+ if (map->map_type != BPF_MAP_TYPE_STACK_TRACE)
+ goto error;
+ break;
+ default:
+ break;
}
return 0;
+error:
+ verbose("cannot pass map_type %d into func %d\n",
+ map->map_type, func_id);
+ return -EINVAL;
}
static int check_call(struct verifier_env *env, int func_id)