crypto: algif_skcipher - Require setkey before accept(2)

commit dd504589577d8e8e70f51f997ad487a4cb6c026f upstream.

Some cipher implementations will crash if you try to use them
without calling setkey first.  This patch adds a check so that
the accept(2) call will fail with -ENOKEY if setkey hasn't been
done on the socket yet.

Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Tested-by: Dmitry Vyukov <dvyukov@google.com>
[bwh: Backported to 3.2: s/crypto_(alloc_|free_)?skcipher/crypto_\1ablkcipher/]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/crypto/algif_skcipher.c b/crypto/algif_skcipher.c
index 83187f4..377010c 100644 (file)
--- a/crypto/algif_skcipher.c
+++ b/crypto/algif_skcipher.c
@@ -31,6 +31,11 @@ struct skcipher_sg_list {
        struct scatterlist sg[0];
 };
 
+struct skcipher_tfm {
+       struct crypto_ablkcipher *skcipher;
+       bool has_key;
+};
+
 struct skcipher_ctx {
        struct list_head tsgl;
        struct af_alg_sgl rsgl;
@@ -546,17 +551,41 @@ static struct proto_ops algif_skcipher_ops = {
 
 static void *skcipher_bind(const char *name, u32 type, u32 mask)
 {
-       return crypto_alloc_ablkcipher(name, type, mask);
+       struct skcipher_tfm *tfm;
+       struct crypto_ablkcipher *skcipher;
+
+       tfm = kzalloc(sizeof(*tfm), GFP_KERNEL);
+       if (!tfm)
+               return ERR_PTR(-ENOMEM);
+
+       skcipher = crypto_alloc_ablkcipher(name, type, mask);
+       if (IS_ERR(skcipher)) {
+               kfree(tfm);
+               return ERR_CAST(skcipher);
+       }
+
+       tfm->skcipher = skcipher;
+
+       return tfm;
 }
 
 static void skcipher_release(void *private)
 {
-       crypto_free_ablkcipher(private);
+       struct skcipher_tfm *tfm = private;
+
+       crypto_free_ablkcipher(tfm->skcipher);
+       kfree(tfm);
 }
 
 static int skcipher_setkey(void *private, const u8 *key, unsigned int keylen)
 {
-       return crypto_ablkcipher_setkey(private, key, keylen);
+       struct skcipher_tfm *tfm = private;
+       int err;
+
+       err = crypto_ablkcipher_setkey(tfm->skcipher, key, keylen);
+       tfm->has_key = !err;
+
+       return err;
 }
 
 static void skcipher_sock_destruct(struct sock *sk)
@@ -575,20 +604,25 @@ static int skcipher_accept_parent(void *private, struct sock *sk)
 {
        struct skcipher_ctx *ctx;
        struct alg_sock *ask = alg_sk(sk);
-       unsigned int len = sizeof(*ctx) + crypto_ablkcipher_reqsize(private);
+       struct skcipher_tfm *tfm = private;
+       struct crypto_ablkcipher *skcipher = tfm->skcipher;
+       unsigned int len = sizeof(*ctx) + crypto_ablkcipher_reqsize(skcipher);
+
+       if (!tfm->has_key)
+               return -ENOKEY;
 
        ctx = sock_kmalloc(sk, len, GFP_KERNEL);
        if (!ctx)
                return -ENOMEM;
 
-       ctx->iv = sock_kmalloc(sk, crypto_ablkcipher_ivsize(private),
+       ctx->iv = sock_kmalloc(sk, crypto_ablkcipher_ivsize(skcipher),
                               GFP_KERNEL);
        if (!ctx->iv) {
                sock_kfree_s(sk, ctx, len);
                return -ENOMEM;
        }
 
-       memset(ctx->iv, 0, crypto_ablkcipher_ivsize(private));
+       memset(ctx->iv, 0, crypto_ablkcipher_ivsize(skcipher));
 
        INIT_LIST_HEAD(&ctx->tsgl);
        ctx->len = len;
@@ -600,7 +634,7 @@ static int skcipher_accept_parent(void *private, struct sock *sk)
 
        ask->private = ctx;
 
-       ablkcipher_request_set_tfm(&ctx->req, private);
+       ablkcipher_request_set_tfm(&ctx->req, skcipher);
        ablkcipher_request_set_callback(&ctx->req, CRYPTO_TFM_REQ_MAY_BACKLOG,
                                        af_alg_complete, &ctx->completion);