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Message-Id: <1471c69eca3022218666f909bc927a92388fd09e.1576580332.git.daniel@iogearbox.net>
Date: Tue, 17 Dec 2019 13:28:16 +0100
From: Daniel Borkmann <daniel@...earbox.net>
To: ast@...nel.org
Cc: netdev@...r.kernel.org, bpf@...r.kernel.org,
Daniel Borkmann <daniel@...earbox.net>,
Roman Gushchin <guro@...com>, Martin KaFai Lau <kafai@...com>
Subject: [PATCH bpf] bpf: Fix cgroup local storage prog tracking
Recently noticed that we're tracking programs related to local storage maps
through their prog pointer. This is a wrong assumption since the prog pointer
can still change throughout the verification process, for example, whenever
bpf_patch_insn_single() is called.
Therefore, the prog pointer that was assigned via bpf_cgroup_storage_assign()
is not guaranteed to be the same as we pass in bpf_cgroup_storage_release()
and the map would therefore remain in busy state forever. Fix this by using
the prog's aux pointer which is stable throughout verification and beyond.
Fixes: de9cbbaadba5 ("bpf: introduce cgroup storage maps")
Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
Cc: Roman Gushchin <guro@...com>
Cc: Martin KaFai Lau <kafai@...com>
---
include/linux/bpf-cgroup.h | 8 ++++----
kernel/bpf/core.c | 3 +--
kernel/bpf/local_storage.c | 24 ++++++++++++------------
kernel/bpf/verifier.c | 2 +-
4 files changed, 18 insertions(+), 19 deletions(-)
diff --git a/include/linux/bpf-cgroup.h b/include/linux/bpf-cgroup.h
index 169fd25f6bc2..9be71c195d74 100644
--- a/include/linux/bpf-cgroup.h
+++ b/include/linux/bpf-cgroup.h
@@ -157,8 +157,8 @@ void bpf_cgroup_storage_link(struct bpf_cgroup_storage *storage,
struct cgroup *cgroup,
enum bpf_attach_type type);
void bpf_cgroup_storage_unlink(struct bpf_cgroup_storage *storage);
-int bpf_cgroup_storage_assign(struct bpf_prog *prog, struct bpf_map *map);
-void bpf_cgroup_storage_release(struct bpf_prog *prog, struct bpf_map *map);
+int bpf_cgroup_storage_assign(struct bpf_prog_aux *aux, struct bpf_map *map);
+void bpf_cgroup_storage_release(struct bpf_prog_aux *aux, struct bpf_map *map);
int bpf_percpu_cgroup_storage_copy(struct bpf_map *map, void *key, void *value);
int bpf_percpu_cgroup_storage_update(struct bpf_map *map, void *key,
@@ -360,9 +360,9 @@ static inline int cgroup_bpf_prog_query(const union bpf_attr *attr,
static inline void bpf_cgroup_storage_set(
struct bpf_cgroup_storage *storage[MAX_BPF_CGROUP_STORAGE_TYPE]) {}
-static inline int bpf_cgroup_storage_assign(struct bpf_prog *prog,
+static inline int bpf_cgroup_storage_assign(struct bpf_prog_aux *aux,
struct bpf_map *map) { return 0; }
-static inline void bpf_cgroup_storage_release(struct bpf_prog *prog,
+static inline void bpf_cgroup_storage_release(struct bpf_prog_aux *aux,
struct bpf_map *map) {}
static inline struct bpf_cgroup_storage *bpf_cgroup_storage_alloc(
struct bpf_prog *prog, enum bpf_cgroup_storage_type stype) { return NULL; }
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 6231858df723..af6b738cf435 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -2043,8 +2043,7 @@ static void bpf_free_cgroup_storage(struct bpf_prog_aux *aux)
for_each_cgroup_storage_type(stype) {
if (!aux->cgroup_storage[stype])
continue;
- bpf_cgroup_storage_release(aux->prog,
- aux->cgroup_storage[stype]);
+ bpf_cgroup_storage_release(aux, aux->cgroup_storage[stype]);
}
}
diff --git a/kernel/bpf/local_storage.c b/kernel/bpf/local_storage.c
index 2ba750725cb2..6bf605dd4b94 100644
--- a/kernel/bpf/local_storage.c
+++ b/kernel/bpf/local_storage.c
@@ -20,7 +20,7 @@ struct bpf_cgroup_storage_map {
struct bpf_map map;
spinlock_t lock;
- struct bpf_prog *prog;
+ struct bpf_prog_aux *aux;
struct rb_root root;
struct list_head list;
};
@@ -420,7 +420,7 @@ const struct bpf_map_ops cgroup_storage_map_ops = {
.map_seq_show_elem = cgroup_storage_seq_show_elem,
};
-int bpf_cgroup_storage_assign(struct bpf_prog *prog, struct bpf_map *_map)
+int bpf_cgroup_storage_assign(struct bpf_prog_aux *aux, struct bpf_map *_map)
{
enum bpf_cgroup_storage_type stype = cgroup_storage_type(_map);
struct bpf_cgroup_storage_map *map = map_to_storage(_map);
@@ -428,14 +428,14 @@ int bpf_cgroup_storage_assign(struct bpf_prog *prog, struct bpf_map *_map)
spin_lock_bh(&map->lock);
- if (map->prog && map->prog != prog)
+ if (map->aux && map->aux != aux)
goto unlock;
- if (prog->aux->cgroup_storage[stype] &&
- prog->aux->cgroup_storage[stype] != _map)
+ if (aux->cgroup_storage[stype] &&
+ aux->cgroup_storage[stype] != _map)
goto unlock;
- map->prog = prog;
- prog->aux->cgroup_storage[stype] = _map;
+ map->aux = aux;
+ aux->cgroup_storage[stype] = _map;
ret = 0;
unlock:
spin_unlock_bh(&map->lock);
@@ -443,16 +443,16 @@ int bpf_cgroup_storage_assign(struct bpf_prog *prog, struct bpf_map *_map)
return ret;
}
-void bpf_cgroup_storage_release(struct bpf_prog *prog, struct bpf_map *_map)
+void bpf_cgroup_storage_release(struct bpf_prog_aux *aux, struct bpf_map *_map)
{
enum bpf_cgroup_storage_type stype = cgroup_storage_type(_map);
struct bpf_cgroup_storage_map *map = map_to_storage(_map);
spin_lock_bh(&map->lock);
- if (map->prog == prog) {
- WARN_ON(prog->aux->cgroup_storage[stype] != _map);
- map->prog = NULL;
- prog->aux->cgroup_storage[stype] = NULL;
+ if (map->aux == aux) {
+ WARN_ON(aux->cgroup_storage[stype] != _map);
+ map->aux = NULL;
+ aux->cgroup_storage[stype] = NULL;
}
spin_unlock_bh(&map->lock);
}
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index a1acdce77070..6ef71429d997 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -8268,7 +8268,7 @@ static int replace_map_fd_with_map_ptr(struct bpf_verifier_env *env)
env->used_maps[env->used_map_cnt++] = map;
if (bpf_map_is_cgroup_storage(map) &&
- bpf_cgroup_storage_assign(env->prog, map)) {
+ bpf_cgroup_storage_assign(env->prog->aux, map)) {
verbose(env, "only one cgroup storage of each type is allowed\n");
fdput(f);
return -EBUSY;
--
2.21.0
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