From 11edb555966ed2c66c533d17c604f9d7e580a829 Mon Sep 17 00:00:00 2001 From: Stephan Mueller Date: Wed, 29 Nov 2017 12:02:23 +0100 Subject: crypto: af_alg - wait for data at beginning of recvmsg The wait for data is a non-atomic operation that can sleep and therefore potentially release the socket lock. The release of the socket lock allows another thread to modify the context data structure. The waiting operation for new data therefore must be called at the beginning of recvmsg. This prevents a race condition where checks of the members of the context data structure are performed by recvmsg while there is a potential for modification of these values. Fixes: e870456d8e7c ("crypto: algif_skcipher - overhaul memory management") Fixes: d887c52d6ae4 ("crypto: algif_aead - overhaul memory management") Reported-by: syzbot Cc: # v4.14+ Signed-off-by: Stephan Mueller Signed-off-by: Herbert Xu --- crypto/algif_skcipher.c | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'crypto/algif_skcipher.c') diff --git a/crypto/algif_skcipher.c b/crypto/algif_skcipher.c index 30cff827dd8f..6fb595cd63ac 100644 --- a/crypto/algif_skcipher.c +++ b/crypto/algif_skcipher.c @@ -72,6 +72,12 @@ static int _skcipher_recvmsg(struct socket *sock, struct msghdr *msg, int err = 0; size_t len = 0; + if (!ctx->used) { + err = af_alg_wait_for_data(sk, flags); + if (err) + return err; + } + /* Allocate cipher request for current operation. */ areq = af_alg_alloc_areq(sk, sizeof(struct af_alg_async_req) + crypto_skcipher_reqsize(tfm)); -- cgit v1.2.3 From d53c5135792319e095bb126bc43b2ee98586f7fe Mon Sep 17 00:00:00 2001 From: Stephan Mueller Date: Fri, 8 Dec 2017 11:50:37 +0100 Subject: crypto: af_alg - fix race accessing cipher request When invoking an asynchronous cipher operation, the invocation of the callback may be performed before the subsequent operations in the initial code path are invoked. The callback deletes the cipher request data structure which implies that after the invocation of the asynchronous cipher operation, this data structure must not be accessed any more. The setting of the return code size with the request data structure must therefore be moved before the invocation of the asynchronous cipher operation. Fixes: e870456d8e7c ("crypto: algif_skcipher - overhaul memory management") Fixes: d887c52d6ae4 ("crypto: algif_aead - overhaul memory management") Reported-by: syzbot Cc: # v4.14+ Signed-off-by: Stephan Mueller Acked-by: Jonathan Cameron Signed-off-by: Herbert Xu --- crypto/algif_aead.c | 10 +++++----- crypto/algif_skcipher.c | 10 +++++----- 2 files changed, 10 insertions(+), 10 deletions(-) (limited to 'crypto/algif_skcipher.c') diff --git a/crypto/algif_aead.c b/crypto/algif_aead.c index c8a32bef208a..b73db2b27656 100644 --- a/crypto/algif_aead.c +++ b/crypto/algif_aead.c @@ -291,6 +291,10 @@ static int _aead_recvmsg(struct socket *sock, struct msghdr *msg, /* AIO operation */ sock_hold(sk); areq->iocb = msg->msg_iocb; + + /* Remember output size that will be generated. */ + areq->outlen = outlen; + aead_request_set_callback(&areq->cra_u.aead_req, CRYPTO_TFM_REQ_MAY_BACKLOG, af_alg_async_cb, areq); @@ -298,12 +302,8 @@ static int _aead_recvmsg(struct socket *sock, struct msghdr *msg, 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; - + if (err == -EINPROGRESS || err == -EBUSY) return -EIOCBQUEUED; - } sock_put(sk); } else { diff --git a/crypto/algif_skcipher.c b/crypto/algif_skcipher.c index 6fb595cd63ac..baef9bfccdda 100644 --- a/crypto/algif_skcipher.c +++ b/crypto/algif_skcipher.c @@ -125,6 +125,10 @@ static int _skcipher_recvmsg(struct socket *sock, struct msghdr *msg, /* AIO operation */ sock_hold(sk); areq->iocb = msg->msg_iocb; + + /* Remember output size that will be generated. */ + areq->outlen = len; + skcipher_request_set_callback(&areq->cra_u.skcipher_req, CRYPTO_TFM_REQ_MAY_SLEEP, af_alg_async_cb, areq); @@ -133,12 +137,8 @@ static int _skcipher_recvmsg(struct socket *sock, struct msghdr *msg, 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; - + if (err == -EINPROGRESS || err == -EBUSY) return -EIOCBQUEUED; - } sock_put(sk); } else { -- cgit v1.2.3 From af955bf15d2c27496b0269b1f05c26f758c68314 Mon Sep 17 00:00:00 2001 From: Jonathan Cameron Date: Tue, 19 Dec 2017 10:27:24 +0000 Subject: crypto: af_alg - Fix race around ctx->rcvused by making it atomic_t This variable was increased and decreased without any protection. Result was an occasional misscount and negative wrap around resulting in false resource allocation failures. Fixes: 7d2c3f54e6f6 ("crypto: af_alg - remove locking in async callback") Signed-off-by: Jonathan Cameron Reviewed-by: Stephan Mueller Signed-off-by: Herbert Xu --- crypto/af_alg.c | 4 ++-- crypto/algif_aead.c | 2 +- crypto/algif_skcipher.c | 2 +- include/crypto/if_alg.h | 5 +++-- 4 files changed, 7 insertions(+), 6 deletions(-) (limited to 'crypto/algif_skcipher.c') diff --git a/crypto/af_alg.c b/crypto/af_alg.c index f1a2caf1b59b..d3f1c431724b 100644 --- a/crypto/af_alg.c +++ b/crypto/af_alg.c @@ -664,7 +664,7 @@ void af_alg_free_areq_sgls(struct af_alg_async_req *areq) unsigned int i; list_for_each_entry_safe(rsgl, tmp, &areq->rsgl_list, list) { - ctx->rcvused -= rsgl->sg_num_bytes; + atomic_sub(rsgl->sg_num_bytes, &ctx->rcvused); af_alg_free_sg(&rsgl->sgl); list_del(&rsgl->list); if (rsgl != &areq->first_rsgl) @@ -1162,7 +1162,7 @@ int af_alg_get_rsgl(struct sock *sk, struct msghdr *msg, int flags, areq->last_rsgl = rsgl; len += err; - ctx->rcvused += err; + atomic_add(err, &ctx->rcvused); rsgl->sg_num_bytes = err; iov_iter_advance(&msg->msg_iter, err); } diff --git a/crypto/algif_aead.c b/crypto/algif_aead.c index b73db2b27656..20df8c1b6851 100644 --- a/crypto/algif_aead.c +++ b/crypto/algif_aead.c @@ -571,7 +571,7 @@ static int aead_accept_parent_nokey(void *private, struct sock *sk) INIT_LIST_HEAD(&ctx->tsgl_list); ctx->len = len; ctx->used = 0; - ctx->rcvused = 0; + atomic_set(&ctx->rcvused, 0); ctx->more = 0; ctx->merge = 0; ctx->enc = 0; diff --git a/crypto/algif_skcipher.c b/crypto/algif_skcipher.c index baef9bfccdda..c5c47b680152 100644 --- a/crypto/algif_skcipher.c +++ b/crypto/algif_skcipher.c @@ -390,7 +390,7 @@ static int skcipher_accept_parent_nokey(void *private, struct sock *sk) INIT_LIST_HEAD(&ctx->tsgl_list); ctx->len = len; ctx->used = 0; - ctx->rcvused = 0; + atomic_set(&ctx->rcvused, 0); ctx->more = 0; ctx->merge = 0; ctx->enc = 0; diff --git a/include/crypto/if_alg.h b/include/crypto/if_alg.h index 38d9c5861ed8..f38227a78eae 100644 --- a/include/crypto/if_alg.h +++ b/include/crypto/if_alg.h @@ -18,6 +18,7 @@ #include #include #include +#include #include #include @@ -150,7 +151,7 @@ struct af_alg_ctx { struct crypto_wait wait; size_t used; - size_t rcvused; + atomic_t rcvused; bool more; bool merge; @@ -215,7 +216,7 @@ static inline int af_alg_rcvbuf(struct sock *sk) struct af_alg_ctx *ctx = ask->private; return max_t(int, max_t(int, sk->sk_rcvbuf & PAGE_MASK, PAGE_SIZE) - - ctx->rcvused, 0); + atomic_read(&ctx->rcvused), 0); } /** -- cgit v1.2.3