crypto: authenc - Move saved IV in front of the ablkcipher request

In crypto_authenc_encrypt() we save the IV behind the ablkcipher
request. To save space on the request, we overwrite the ablkcipher
request with a ahash request after encryption. So the IV may be
overwritten by the ahash request. This patch fixes this by placing
the IV in front of the ablkcipher/ahash request.

Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/crypto/authenc.c b/crypto/authenc.c
index 6287cfd..2bb7348 100644 (file)
--- a/crypto/authenc.c
+++ b/crypto/authenc.c
@@ -386,11 +386,13 @@ static int crypto_authenc_encrypt(struct aead_request *req)
 {
        struct crypto_aead *authenc = crypto_aead_reqtfm(req);
        struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
-       struct ablkcipher_request *abreq = aead_request_ctx(req);
+       struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
        struct crypto_ablkcipher *enc = ctx->enc;
        struct scatterlist *dst = req->dst;
        unsigned int cryptlen = req->cryptlen;
-       u8 *iv = (u8 *)(abreq + 1) + crypto_ablkcipher_reqsize(enc);
+       struct ablkcipher_request *abreq = (void *)(areq_ctx->tail
+                                                   + ctx->reqoff);
+       u8 *iv = (u8 *)abreq - crypto_ablkcipher_ivsize(enc);
        int err;
 
        ablkcipher_request_set_tfm(abreq, enc);
@@ -546,10 +548,6 @@ static int crypto_authenc_init_tfm(struct crypto_tfm *tfm)
        if (IS_ERR(auth))
                return PTR_ERR(auth);
 
-       ctx->reqoff = ALIGN(2 * crypto_ahash_digestsize(auth) +
-                           crypto_ahash_alignmask(auth),
-                           crypto_ahash_alignmask(auth) + 1);
-
        enc = crypto_spawn_skcipher(&ictx->enc);
        err = PTR_ERR(enc);
        if (IS_ERR(enc))
@@ -558,13 +556,18 @@ static int crypto_authenc_init_tfm(struct crypto_tfm *tfm)
        ctx->auth = auth;
        ctx->enc = enc;
 
-       tfm->crt_aead.reqsize = max_t(unsigned int,
-                               crypto_ahash_reqsize(auth) + ctx->reqoff +
-                               sizeof(struct authenc_request_ctx) +
+       ctx->reqoff = ALIGN(2 * crypto_ahash_digestsize(auth) +
+                           crypto_ahash_alignmask(auth),
+                           crypto_ahash_alignmask(auth) + 1) +
+                     crypto_ablkcipher_ivsize(enc);
+
+       tfm->crt_aead.reqsize = sizeof(struct authenc_request_ctx) +
+                               ctx->reqoff +
+                               max_t(unsigned int,
+                               crypto_ahash_reqsize(auth) +
                                sizeof(struct ahash_request),
                                sizeof(struct skcipher_givcrypt_request) +
-                               crypto_ablkcipher_reqsize(enc) +
-                               crypto_ablkcipher_ivsize(enc));
+                               crypto_ablkcipher_reqsize(enc));
 
        return 0;