[PATCH 4.4 086/117] crypto: algif_hash - Require setkey before accept(2)

Greg Kroah-Hartman
2016-02-15T00:25:45Z

From: Herbert Xu <herbert@gondor.apana.org.au>

commit 6de62f15b581f920ade22d758f4c338311c2f0d4 upstream.

Hash implementations that require a key may crash if you use
them without setting a key. This patch adds the necessary checks
so that if you do attempt to use them without a key that we return
-ENOKEY instead of proceeding.

This patch also adds a compatibility path to support old applications
that do acept(2) before setkey.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
crypto/algif_hash.c | 201 +++++++++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 193 insertions(+), 8 deletions(-)

--- a/crypto/algif_hash.c
+++ b/crypto/algif_hash.c
@@ -34,6 +34,11 @@ struct hash_ctx {
struct ahash_request req;
};

+struct algif_hash_tfm {
+ struct crypto_ahash *hash;
+ bool has_key;
+};
+
static int hash_sendmsg(struct socket *sock, struct msghdr *msg,
size_t ignored)
{
@@ -235,22 +240,151 @@ static struct proto_ops algif_hash_ops =
.accept = hash_accept,
};

+static int hash_check_key(struct socket *sock)
+{
+ int err;
+ struct sock *psk;
+ struct alg_sock *pask;
+ struct algif_hash_tfm *tfm;
+ struct sock *sk = sock->sk;
+ struct alg_sock *ask = alg_sk(sk);
+
+ if (ask->refcnt)
+ return 0;
+
+ psk = ask->parent;
+ pask = alg_sk(ask->parent);
+ tfm = pask->private;
+
+ err = -ENOKEY;
+ lock_sock(psk);
+ if (!tfm->has_key)
+ goto unlock;
+
+ if (!pask->refcnt++)
+ sock_hold(psk);
+
+ ask->refcnt = 1;
+ sock_put(psk);
+
+ err = 0;
+
+unlock:
+ release_sock(psk);
+
+ return err;
+}
+
+static int hash_sendmsg_nokey(struct socket *sock, struct msghdr *msg,
+ size_t size)
+{
+ int err;
+
+ err = hash_check_key(sock);
+ if (err)
+ return err;
+
+ return hash_sendmsg(sock, msg, size);
+}
+
+static ssize_t hash_sendpage_nokey(struct socket *sock, struct page *page,
+ int offset, size_t size, int flags)
+{
+ int err;
+
+ err = hash_check_key(sock);
+ if (err)
+ return err;
+
+ return hash_sendpage(sock, page, offset, size, flags);
+}
+
+static int hash_recvmsg_nokey(struct socket *sock, struct msghdr *msg,
+ size_t ignored, int flags)
+{
+ int err;
+
+ err = hash_check_key(sock);
+ if (err)
+ return err;
+
+ return hash_recvmsg(sock, msg, ignored, flags);
+}
+
+static int hash_accept_nokey(struct socket *sock, struct socket *newsock,
+ int flags)
+{
+ int err;
+
+ err = hash_check_key(sock);
+ if (err)
+ return err;
+
+ return hash_accept(sock, newsock, flags);
+}
+
+static struct proto_ops algif_hash_ops_nokey = {
+ .family = PF_ALG,
+
+ .connect = sock_no_connect,
+ .socketpair = sock_no_socketpair,
+ .getname = sock_no_getname,
+ .ioctl = sock_no_ioctl,
+ .listen = sock_no_listen,
+ .shutdown = sock_no_shutdown,
+ .getsockopt = sock_no_getsockopt,
+ .mmap = sock_no_mmap,
+ .bind = sock_no_bind,
+ .setsockopt = sock_no_setsockopt,
+ .poll = sock_no_poll,
+
+ .release = af_alg_release,
+ .sendmsg = hash_sendmsg_nokey,
+ .sendpage = hash_sendpage_nokey,
+ .recvmsg = hash_recvmsg_nokey,
+ .accept = hash_accept_nokey,
+};
+
static void *hash_bind(const char *name, u32 type, u32 mask)
{
- return crypto_alloc_ahash(name, type, mask);
+ struct algif_hash_tfm *tfm;
+ struct crypto_ahash *hash;
+
+ tfm = kzalloc(sizeof(*tfm), GFP_KERNEL);
+ if (!tfm)
+ return ERR_PTR(-ENOMEM);
+
+ hash = crypto_alloc_ahash(name, type, mask);
+ if (IS_ERR(hash)) {
+ kfree(tfm);
+ return ERR_CAST(hash);
+ }
+
+ tfm->hash = hash;
+
+ return tfm;
}

static void hash_release(void *private)
{
- crypto_free_ahash(private);
+ struct algif_hash_tfm *tfm = private;
+
+ crypto_free_ahash(tfm->hash);
+ kfree(tfm);
}

static int hash_setkey(void *private, const u8 *key, unsigned int keylen)
{
- return crypto_ahash_setkey(private, key, keylen);
+ struct algif_hash_tfm *tfm = private;
+ int err;
+
+ err = crypto_ahash_setkey(tfm->hash, key, keylen);
+ tfm->has_key = !err;
+
+ return err;
}

-static void hash_sock_destruct(struct sock *sk)
+static void hash_sock_destruct_common(struct sock *sk)
{
struct alg_sock *ask = alg_sk(sk);
struct hash_ctx *ctx = ask->private;
@@ -258,15 +392,40 @@ static void hash_sock_destruct(struct so
sock_kzfree_s(sk, ctx->result,
crypto_ahash_digestsize(crypto_ahash_reqtfm(&ctx->req)));
sock_kfree_s(sk, ctx, ctx->len);
+}
+
+static void hash_sock_destruct(struct sock *sk)
+{
+ hash_sock_destruct_common(sk);
af_alg_release_parent(sk);
}

-static int hash_accept_parent(void *private, struct sock *sk)
+static void hash_release_parent_nokey(struct sock *sk)
+{
+ struct alg_sock *ask = alg_sk(sk);
+
+ if (!ask->refcnt) {
+ sock_put(ask->parent);
+ return;
+ }
+
+ af_alg_release_parent(sk);
+}
+
+static void hash_sock_destruct_nokey(struct sock *sk)
+{
+ hash_sock_destruct_common(sk);
+ hash_release_parent_nokey(sk);
+}
+
+static int hash_accept_parent_common(void *private, struct sock *sk)
{
struct hash_ctx *ctx;
struct alg_sock *ask = alg_sk(sk);
- unsigned len = sizeof(*ctx) + crypto_ahash_reqsize(private);
- unsigned ds = crypto_ahash_digestsize(private);
+ struct algif_hash_tfm *tfm = private;
+ struct crypto_ahash *hash = tfm->hash;
+ unsigned len = sizeof(*ctx) + crypto_ahash_reqsize(hash);
+ unsigned ds = crypto_ahash_digestsize(hash);

ctx = sock_kmalloc(sk, len, GFP_KERNEL);
if (!ctx)
@@ -286,7 +445,7 @@ static int hash_accept_parent(void *priv

ask->private = ctx;

- ahash_request_set_tfm(&ctx->req, private);
+ ahash_request_set_tfm(&ctx->req, hash);
ahash_request_set_callback(&ctx->req, CRYPTO_TFM_REQ_MAY_BACKLOG,
af_alg_complete, &ctx->completion);

@@ -295,12 +454,38 @@ static int hash_accept_parent(void *priv
return 0;
}

+static int hash_accept_parent(void *private, struct sock *sk)
+{
+ struct algif_hash_tfm *tfm = private;
+
+ if (!tfm->has_key && crypto_ahash_has_setkey(tfm->hash))
+ return -ENOKEY;
+
+ return hash_accept_parent_common(private, sk);
+}
+
+static int hash_accept_parent_nokey(void *private, struct sock *sk)
+{
+ int err;
+
+ err = hash_accept_parent_common(private, sk);
+ if (err)
+ goto out;
+
+ sk->sk_destruct = hash_sock_destruct_nokey;
+
+out:
+ return err;
+}
+
static const struct af_alg_type algif_type_hash = {
.bind = hash_bind,
.release = hash_release,
.setkey = hash_setkey,
.accept = hash_accept_parent,
+ .accept_nokey = hash_accept_parent_nokey,
.ops = &algif_hash_ops,
+ .ops_nokey = &algif_hash_ops_nokey,
.name = "hash",
.owner = THIS_MODULE
};