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author | Stanislav Fomichev <sdf@google.com> | 2019-05-28 14:14:41 -0700 |
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committer | Daniel Borkmann <daniel@iogearbox.net> | 2019-05-29 15:17:35 +0200 |
commit | 54e9c9d4b506b611228890752d1cfa960e0965e1 (patch) | |
tree | 161234d2c743f998381c993190e52d1aa3790614 /include/linux/bpf.h | |
parent | fe937ea12ec83da6c6bbbdb54a03062155318d0e (diff) | |
download | linux-54e9c9d4b506b611228890752d1cfa960e0965e1.tar.gz linux-54e9c9d4b506b611228890752d1cfa960e0965e1.tar.bz2 linux-54e9c9d4b506b611228890752d1cfa960e0965e1.zip |
bpf: remove __rcu annotations from bpf_prog_array
Drop __rcu annotations and rcu read sections from bpf_prog_array
helper functions. They are not needed since all existing callers
call those helpers from the rcu update side while holding a mutex.
This guarantees that use-after-free could not happen.
In the next patches I'll fix the callers with missing
rcu_dereference_protected to make sparse/lockdep happy, the proper
way to use these helpers is:
struct bpf_prog_array __rcu *progs = ...;
struct bpf_prog_array *p;
mutex_lock(&mtx);
p = rcu_dereference_protected(progs, lockdep_is_held(&mtx));
bpf_prog_array_length(p);
bpf_prog_array_copy_to_user(p, ...);
bpf_prog_array_delete_safe(p, ...);
bpf_prog_array_copy_info(p, ...);
bpf_prog_array_copy(p, ...);
bpf_prog_array_free(p);
mutex_unlock(&mtx);
No functional changes! rcu_dereference_protected with lockdep_is_held
should catch any cases where we update prog array without a mutex
(I've looked at existing call sites and I think we hold a mutex
everywhere).
Motivation is to fix sparse warnings:
kernel/bpf/core.c:1803:9: warning: incorrect type in argument 1 (different address spaces)
kernel/bpf/core.c:1803:9: expected struct callback_head *head
kernel/bpf/core.c:1803:9: got struct callback_head [noderef] <asn:4> *
kernel/bpf/core.c:1877:44: warning: incorrect type in initializer (different address spaces)
kernel/bpf/core.c:1877:44: expected struct bpf_prog_array_item *item
kernel/bpf/core.c:1877:44: got struct bpf_prog_array_item [noderef] <asn:4> *
kernel/bpf/core.c:1901:26: warning: incorrect type in assignment (different address spaces)
kernel/bpf/core.c:1901:26: expected struct bpf_prog_array_item *existing
kernel/bpf/core.c:1901:26: got struct bpf_prog_array_item [noderef] <asn:4> *
kernel/bpf/core.c:1935:26: warning: incorrect type in assignment (different address spaces)
kernel/bpf/core.c:1935:26: expected struct bpf_prog_array_item *[assigned] existing
kernel/bpf/core.c:1935:26: got struct bpf_prog_array_item [noderef] <asn:4> *
v2:
* remove comment about potential race; that can't happen
because all callers are in rcu-update section
Cc: Roman Gushchin <guro@fb.com>
Acked-by: Roman Gushchin <guro@fb.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Diffstat (limited to 'include/linux/bpf.h')
-rw-r--r-- | include/linux/bpf.h | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index d98141edb74b..ff3e00ff84d2 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -514,17 +514,17 @@ struct bpf_prog_array { }; struct bpf_prog_array *bpf_prog_array_alloc(u32 prog_cnt, gfp_t flags); -void bpf_prog_array_free(struct bpf_prog_array __rcu *progs); -int bpf_prog_array_length(struct bpf_prog_array __rcu *progs); -int bpf_prog_array_copy_to_user(struct bpf_prog_array __rcu *progs, +void bpf_prog_array_free(struct bpf_prog_array *progs); +int bpf_prog_array_length(struct bpf_prog_array *progs); +int bpf_prog_array_copy_to_user(struct bpf_prog_array *progs, __u32 __user *prog_ids, u32 cnt); -void bpf_prog_array_delete_safe(struct bpf_prog_array __rcu *progs, +void bpf_prog_array_delete_safe(struct bpf_prog_array *progs, struct bpf_prog *old_prog); -int bpf_prog_array_copy_info(struct bpf_prog_array __rcu *array, +int bpf_prog_array_copy_info(struct bpf_prog_array *array, u32 *prog_ids, u32 request_cnt, u32 *prog_cnt); -int bpf_prog_array_copy(struct bpf_prog_array __rcu *old_array, +int bpf_prog_array_copy(struct bpf_prog_array *old_array, struct bpf_prog *exclude_prog, struct bpf_prog *include_prog, struct bpf_prog_array **new_array); |