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crypto: af_alg - remove locking in async callback

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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
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23
crypto/algif_skcipher.c
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@@ -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;
}