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crypto: af_alg - remove locking in async callback 

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.

Cc: <stable@vger.kernel.org>
Fixes: e870456d8e ("crypto: algif_skcipher - overhaul memory management")
Fixes: d887c52d6a ("crypto: algif_aead - overhaul memory management")
Reported-by: Romain Izard <romain.izard.pro@gmail.com>
Signed-off-by: Stephan Mueller <smueller@chronox.de>
Tested-by: Romain Izard <romain.izard.pro@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Stephan Mueller 2017-11-10 13:20:55 +01:00 committed by Herbert Xu
parent 8e1fa89aa8
commit 7d2c3f54e6
4 changed files with 39 additions and 29 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
crypto/af_alg.c
View File

@ -1020,6 +1020,18 @@ unlock:
}
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
*
@ -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);

23
crypto/algif_aead.c
View File

@ -283,12 +283,23 @@ 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,
@ -300,19 +311,9 @@ 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;
}

23
crypto/algif_skcipher.c
View File

@ -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;
}

1
include/crypto/if_alg.h
View File

@ -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);