From: Daniel Borkmann <daniel@iogearbox.net>
Date: Mon, 16 Dec 2019 17:49:00 +0100
Subject: bpf: Fix missing prog untrack in release_maps
Patch-mainline: v5.5-rc3
Git-commit: a2ea07465c8d7984cc6b8b1f0b3324f9b138094a
References: bsc#1155518
Commit da765a2f5993 ("bpf: Add poke dependency tracking for prog array
maps") wrongly assumed that in case of prog load errors, we're cleaning
up all program tracking via bpf_free_used_maps().
However, it can happen that we're still at the point where we didn't copy
map pointers into the prog's aux section such that env->prog->aux->used_maps
is still zero, running into a UAF. In such case, the verifier has similar
release_maps() helper that drops references to used maps from its env.
Consolidate the release code into __bpf_free_used_maps() and call it from
all sides to fix it.
Fixes: da765a2f5993 ("bpf: Add poke dependency tracking for prog array maps")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/1c2909484ca524ae9f55109b06f22b6213e76376.1576514756.git.daniel@iogearbox.net
Acked-by: Gary Lin <glin@suse.com>
---
include/linux/bpf.h | 2 ++
kernel/bpf/core.c | 14 ++++++++++----
kernel/bpf/verifier.c | 14 ++------------
3 files changed, 14 insertions(+), 16 deletions(-)
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -817,6 +817,8 @@ struct bpf_prog * __must_check bpf_prog_
void bpf_prog_put(struct bpf_prog *prog);
int __bpf_prog_charge(struct user_struct *user, u32 pages);
void __bpf_prog_uncharge(struct user_struct *user, u32 pages);
+void __bpf_free_used_maps(struct bpf_prog_aux *aux,
+ struct bpf_map **used_maps, u32 len);
void bpf_prog_free_id(struct bpf_prog *prog, bool do_idr_lock);
void bpf_map_free_id(struct bpf_map *map, bool do_idr_lock);
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -2048,18 +2048,24 @@ static void bpf_free_cgroup_storage(stru
}
}
-static void bpf_free_used_maps(struct bpf_prog_aux *aux)
+void __bpf_free_used_maps(struct bpf_prog_aux *aux,
+ struct bpf_map **used_maps, u32 len)
{
struct bpf_map *map;
- int i;
+ u32 i;
bpf_free_cgroup_storage(aux);
- for (i = 0; i < aux->used_map_cnt; i++) {
- map = aux->used_maps[i];
+ for (i = 0; i < len; i++) {
+ map = used_maps[i];
if (map->ops->map_poke_untrack)
map->ops->map_poke_untrack(map, aux);
bpf_map_put(map);
}
+}
+
+static void bpf_free_used_maps(struct bpf_prog_aux *aux)
+{
+ __bpf_free_used_maps(aux, aux->used_maps, aux->used_map_cnt);
kfree(aux->used_maps);
}
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -8298,18 +8298,8 @@ next_insn:
/* drop refcnt of maps used by the rejected program */
static void release_maps(struct bpf_verifier_env *env)
{
- enum bpf_cgroup_storage_type stype;
- int i;
-
- for_each_cgroup_storage_type(stype) {
- if (!env->prog->aux->cgroup_storage[stype])
- continue;
- bpf_cgroup_storage_release(env->prog,
- env->prog->aux->cgroup_storage[stype]);
- }
-
- for (i = 0; i < env->used_map_cnt; i++)
- bpf_map_put(env->used_maps[i]);
+ __bpf_free_used_maps(env->prog->aux, env->used_maps,
+ env->used_map_cnt);
}
/* convert pseudo BPF_LD_IMM64 into generic BPF_LD_IMM64 */