From: Herbert Xu <herb...@gondor.apana.org.au> commit 34c86f4c4a7be3b3e35aa48bd18299d4c756064d upstream.
The locking in af_alg_release_parent is broken as the BH socket lock can only be taken if there is a code-path to handle the case where the lock is owned by process-context. Instead of adding such handling, we can fix this by changing the ref counts to atomic_t. This patch also modifies the main refcnt to include both normal and nokey sockets. This way we don't have to fudge the nokey ref count when a socket changes from nokey to normal. Credits go to Mauricio Faria de Oliveira who diagnosed this bug and sent a patch for it: https://lore.kernel.org/linux-crypto/20200605161657.535043-1-...@canonical.com/ Reported-by: Brian Moyles <bmoy...@netflix.com> Reported-by: Mauricio Faria de Oliveira <m...@canonical.com> Fixes: 37f96694cf73 ("crypto: af_alg - Use bh_lock_sock in...") Cc: <sta...@vger.kernel.org> Signed-off-by: Herbert Xu <herb...@gondor.apana.org.au> Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> --- crypto/af_alg.c | 26 +++++++++++--------------- crypto/algif_aead.c | 9 +++------ crypto/algif_hash.c | 9 +++------ crypto/algif_skcipher.c | 9 +++------ include/crypto/if_alg.h | 4 ++-- 5 files changed, 22 insertions(+), 35 deletions(-) --- a/crypto/af_alg.c +++ b/crypto/af_alg.c @@ -133,21 +133,15 @@ EXPORT_SYMBOL_GPL(af_alg_release); void af_alg_release_parent(struct sock *sk) { struct alg_sock *ask = alg_sk(sk); - unsigned int nokey = ask->nokey_refcnt; - bool last = nokey && !ask->refcnt; + unsigned int nokey = atomic_read(&ask->nokey_refcnt); sk = ask->parent; ask = alg_sk(sk); - local_bh_disable(); - bh_lock_sock(sk); - ask->nokey_refcnt -= nokey; - if (!last) - last = !--ask->refcnt; - bh_unlock_sock(sk); - local_bh_enable(); + if (nokey) + atomic_dec(&ask->nokey_refcnt); - if (last) + if (atomic_dec_and_test(&ask->refcnt)) sock_put(sk); } EXPORT_SYMBOL_GPL(af_alg_release_parent); @@ -192,7 +186,7 @@ static int alg_bind(struct socket *sock, err = -EBUSY; lock_sock(sk); - if (ask->refcnt | ask->nokey_refcnt) + if (atomic_read(&ask->refcnt)) goto unlock; swap(ask->type, type); @@ -241,7 +235,7 @@ static int alg_setsockopt(struct socket int err = -EBUSY; lock_sock(sk); - if (ask->refcnt) + if (atomic_read(&ask->refcnt) != atomic_read(&ask->nokey_refcnt)) goto unlock; type = ask->type; @@ -308,12 +302,14 @@ int af_alg_accept(struct sock *sk, struc sk2->sk_family = PF_ALG; - if (nokey || !ask->refcnt++) + if (atomic_inc_return_relaxed(&ask->refcnt) == 1) sock_hold(sk); - ask->nokey_refcnt += nokey; + if (nokey) { + atomic_inc(&ask->nokey_refcnt); + atomic_set(&alg_sk(sk2)->nokey_refcnt, 1); + } alg_sk(sk2)->parent = sk; alg_sk(sk2)->type = type; - alg_sk(sk2)->nokey_refcnt = nokey; newsock->ops = type->ops; newsock->state = SS_CONNECTED; --- a/crypto/algif_aead.c +++ b/crypto/algif_aead.c @@ -388,7 +388,7 @@ static int aead_check_key(struct socket struct alg_sock *ask = alg_sk(sk); lock_sock(sk); - if (ask->refcnt) + if (!atomic_read(&ask->nokey_refcnt)) goto unlock_child; psk = ask->parent; @@ -400,11 +400,8 @@ static int aead_check_key(struct socket if (crypto_aead_get_flags(tfm->aead) & CRYPTO_TFM_NEED_KEY) goto unlock; - if (!pask->refcnt++) - sock_hold(psk); - - ask->refcnt = 1; - sock_put(psk); + atomic_dec(&pask->nokey_refcnt); + atomic_set(&ask->nokey_refcnt, 0); err = 0; --- a/crypto/algif_hash.c +++ b/crypto/algif_hash.c @@ -306,7 +306,7 @@ static int hash_check_key(struct socket struct alg_sock *ask = alg_sk(sk); lock_sock(sk); - if (ask->refcnt) + if (!atomic_read(&ask->nokey_refcnt)) goto unlock_child; psk = ask->parent; @@ -318,11 +318,8 @@ static int hash_check_key(struct socket if (crypto_ahash_get_flags(tfm) & CRYPTO_TFM_NEED_KEY) goto unlock; - if (!pask->refcnt++) - sock_hold(psk); - - ask->refcnt = 1; - sock_put(psk); + atomic_dec(&pask->nokey_refcnt); + atomic_set(&ask->nokey_refcnt, 0); err = 0; --- a/crypto/algif_skcipher.c +++ b/crypto/algif_skcipher.c @@ -215,7 +215,7 @@ static int skcipher_check_key(struct soc struct alg_sock *ask = alg_sk(sk); lock_sock(sk); - if (ask->refcnt) + if (!atomic_read(&ask->nokey_refcnt)) goto unlock_child; psk = ask->parent; @@ -227,11 +227,8 @@ static int skcipher_check_key(struct soc if (crypto_skcipher_get_flags(tfm) & CRYPTO_TFM_NEED_KEY) goto unlock; - if (!pask->refcnt++) - sock_hold(psk); - - ask->refcnt = 1; - sock_put(psk); + atomic_dec(&pask->nokey_refcnt); + atomic_set(&ask->nokey_refcnt, 0); err = 0; --- a/include/crypto/if_alg.h +++ b/include/crypto/if_alg.h @@ -34,8 +34,8 @@ struct alg_sock { struct sock *parent; - unsigned int refcnt; - unsigned int nokey_refcnt; + atomic_t refcnt; + atomic_t nokey_refcnt; const struct af_alg_type *type; void *private;
