From: Stephan =?ISO-8859-1?Q?M=FCller?= Subject: [PATCH v3] crypto: AF_ALG - remove locking in async callback Date: Fri, 10 Nov 2017 13:20:55 +0100 Message-ID: <1966139.WIlnTlQG5u@positron.chronox.de> References: <2510520.gYBNS8MAsP@positron.chronox.de> <20171110111058.GA25914@gondor.apana.org.au> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Cc: Romain Izard , linux-crypto@vger.kernel.org, Cyrille Pitchen , Tudor Ambarus , Nicolas Ferre , linux-arm-kernel To: Herbert Xu Return-path: Received: from mail.eperm.de ([89.247.134.16]:42236 "EHLO mail.eperm.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752257AbdKJMU6 (ORCPT ); Fri, 10 Nov 2017 07:20:58 -0500 In-Reply-To: <20171110111058.GA25914@gondor.apana.org.au> Sender: linux-crypto-owner@vger.kernel.org List-ID: The code paths protected by the socket-lock do not use or modify the socket in a non-atomic fashion. The actions pertaining the socket do not even need to be handled as an atomic operation. Thus, the socket-lock can be safely ignored. This fixes a bug regarding scheduling in atomic as the callback function may be invoked in interrupt context. In addition, the sock_hold is moved before the AIO encrypt/decrypt operation to ensure that the socket is always present. This avoids a tiny race window where the socket is unprotected and yet used by the AIO operation. Finally, the release of resources for a crypto operation is moved into a common function of af_alg_free_resources. Fixes: e870456d8e7c8 ("crypto: algif_skcipher - overhaul memory management") Fixes: d887c52d6ae43 ("crypto: algif_aead - overhaul memory management") Reported-by: Romain Izard Signed-off-by: Stephan Mueller --- crypto/af_alg.c | 21 ++++++++++++++------- crypto/algif_aead.c | 23 ++++++++++++----------- crypto/algif_skcipher.c | 23 ++++++++++++----------- include/crypto/if_alg.h | 1 + 4 files changed, 39 insertions(+), 29 deletions(-) diff --git a/crypto/af_alg.c b/crypto/af_alg.c index 85cea9de324a..358749c38894 100644 --- a/crypto/af_alg.c +++ b/crypto/af_alg.c @@ -1021,6 +1021,18 @@ ssize_t af_alg_sendpage(struct socket *sock, struct page *page, EXPORT_SYMBOL_GPL(af_alg_sendpage); /** + * af_alg_free_resources - release resources required for crypto request + */ +void af_alg_free_resources(struct af_alg_async_req *areq) +{ + struct sock *sk = areq->sk; + + af_alg_free_areq_sgls(areq); + sock_kfree_s(sk, areq, areq->areqlen); +} +EXPORT_SYMBOL_GPL(af_alg_free_resources); + +/** * af_alg_async_cb - AIO callback handler * * This handler cleans up the struct af_alg_async_req upon completion of the @@ -1036,18 +1048,13 @@ void af_alg_async_cb(struct crypto_async_request *_req, int err) struct kiocb *iocb = areq->iocb; unsigned int resultlen; - lock_sock(sk); - /* Buffer size written by crypto operation. */ resultlen = areq->outlen; - af_alg_free_areq_sgls(areq); - sock_kfree_s(sk, areq, areq->areqlen); - __sock_put(sk); + af_alg_free_resources(areq); + sock_put(sk); iocb->ki_complete(iocb, err ? err : resultlen, 0); - - release_sock(sk); } EXPORT_SYMBOL_GPL(af_alg_async_cb); diff --git a/crypto/algif_aead.c b/crypto/algif_aead.c index aacae0837aff..db9378a45296 100644 --- a/crypto/algif_aead.c +++ b/crypto/algif_aead.c @@ -268,12 +268,23 @@ static int _aead_recvmsg(struct socket *sock, struct msghdr *msg, if (msg->msg_iocb && !is_sync_kiocb(msg->msg_iocb)) { /* AIO operation */ + sock_hold(sk); areq->iocb = msg->msg_iocb; aead_request_set_callback(&areq->cra_u.aead_req, CRYPTO_TFM_REQ_MAY_BACKLOG, af_alg_async_cb, areq); err = ctx->enc ? crypto_aead_encrypt(&areq->cra_u.aead_req) : crypto_aead_decrypt(&areq->cra_u.aead_req); + + /* AIO operation in progress */ + if (err == -EINPROGRESS || err == -EBUSY) { + /* Remember output size that will be generated. */ + areq->outlen = outlen; + + return -EIOCBQUEUED; + } + + sock_put(sk); } else { /* Synchronous operation */ aead_request_set_callback(&areq->cra_u.aead_req, @@ -285,19 +296,9 @@ static int _aead_recvmsg(struct socket *sock, struct msghdr *msg, &ctx->wait); } - /* AIO operation in progress */ - if (err == -EINPROGRESS) { - sock_hold(sk); - - /* Remember output size that will be generated. */ - areq->outlen = outlen; - - return -EIOCBQUEUED; - } free: - af_alg_free_areq_sgls(areq); - sock_kfree_s(sk, areq, areq->areqlen); + af_alg_free_resources(areq); return err ? err : outlen; } diff --git a/crypto/algif_skcipher.c b/crypto/algif_skcipher.c index 9954b078f0b9..30cff827dd8f 100644 --- a/crypto/algif_skcipher.c +++ b/crypto/algif_skcipher.c @@ -117,6 +117,7 @@ static int _skcipher_recvmsg(struct socket *sock, struct msghdr *msg, if (msg->msg_iocb && !is_sync_kiocb(msg->msg_iocb)) { /* AIO operation */ + sock_hold(sk); areq->iocb = msg->msg_iocb; skcipher_request_set_callback(&areq->cra_u.skcipher_req, CRYPTO_TFM_REQ_MAY_SLEEP, @@ -124,6 +125,16 @@ static int _skcipher_recvmsg(struct socket *sock, struct msghdr *msg, err = ctx->enc ? crypto_skcipher_encrypt(&areq->cra_u.skcipher_req) : crypto_skcipher_decrypt(&areq->cra_u.skcipher_req); + + /* AIO operation in progress */ + if (err == -EINPROGRESS || err == -EBUSY) { + /* Remember output size that will be generated. */ + areq->outlen = len; + + return -EIOCBQUEUED; + } + + sock_put(sk); } else { /* Synchronous operation */ skcipher_request_set_callback(&areq->cra_u.skcipher_req, @@ -136,19 +147,9 @@ static int _skcipher_recvmsg(struct socket *sock, struct msghdr *msg, &ctx->wait); } - /* AIO operation in progress */ - if (err == -EINPROGRESS) { - sock_hold(sk); - - /* Remember output size that will be generated. */ - areq->outlen = len; - - return -EIOCBQUEUED; - } free: - af_alg_free_areq_sgls(areq); - sock_kfree_s(sk, areq, areq->areqlen); + af_alg_free_resources(areq); return err ? err : len; } diff --git a/include/crypto/if_alg.h b/include/crypto/if_alg.h index 6abf0a3604dc..38d9c5861ed8 100644 --- a/include/crypto/if_alg.h +++ b/include/crypto/if_alg.h @@ -242,6 +242,7 @@ int af_alg_sendmsg(struct socket *sock, struct msghdr *msg, size_t size, unsigned int ivsize); ssize_t af_alg_sendpage(struct socket *sock, struct page *page, int offset, size_t size, int flags); +void af_alg_free_resources(struct af_alg_async_req *areq); void af_alg_async_cb(struct crypto_async_request *_req, int err); unsigned int af_alg_poll(struct file *file, struct socket *sock, poll_table *wait); -- 2.13.6