crypto: authencesn - Do not place hiseq at end of dst for out-of-place decryption

When decrypting data that is not in-place (src != dst), there is
no need to save the high-order sequence bits in dst as it could
simply be re-copied from the source.

However, the data to be hashed need to be rearranged accordingly.

Reported-by: Taeyang Lee <0wn@theori.io>
Fixes: 104880a6b470 ("crypto: authencesn - Convert to new AEAD interface")
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Thanks,

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/crypto/authencesn.c b/crypto/authencesn.c
index 542a978663b9e7230cbe6546507579e0782b5d37..c0a01d738d9bc3922b35e23231edcb4e9a7921f9 100644 (file)
--- a/crypto/authencesn.c
+++ b/crypto/authencesn.c
@@ -207,6 +207,7 @@ static int crypto_authenc_esn_decrypt_tail(struct aead_request *req,
        u8 *ohash = areq_ctx->tail;
        unsigned int cryptlen = req->cryptlen - authsize;
        unsigned int assoclen = req->assoclen;
+       struct scatterlist *src = req->src;
        struct scatterlist *dst = req->dst;
        u8 *ihash = ohash + crypto_ahash_digestsize(auth);
        u32 tmp[2];
@@ -214,23 +215,27 @@ static int crypto_authenc_esn_decrypt_tail(struct aead_request *req,
        if (!authsize)
                goto decrypt;
 
-       /* Move high-order bits of sequence number back. */
-       scatterwalk_map_and_copy(tmp, dst, 4, 4, 0);
-       scatterwalk_map_and_copy(tmp + 1, dst, assoclen + cryptlen, 4, 0);
-       scatterwalk_map_and_copy(tmp, dst, 0, 8, 1);
+       if (src == dst) {
+               /* Move high-order bits of sequence number back. */
+               scatterwalk_map_and_copy(tmp, dst, 4, 4, 0);
+               scatterwalk_map_and_copy(tmp + 1, dst, assoclen + cryptlen, 4, 0);
+               scatterwalk_map_and_copy(tmp, dst, 0, 8, 1);
+       } else
+               memcpy_sglist(dst, src, assoclen);
 
        if (crypto_memneq(ihash, ohash, authsize))
                return -EBADMSG;
 
 decrypt:
 
-       sg_init_table(areq_ctx->dst, 2);
+       if (src != dst)
+               src = scatterwalk_ffwd(areq_ctx->src, src, assoclen);
        dst = scatterwalk_ffwd(areq_ctx->dst, dst, assoclen);
 
        skcipher_request_set_tfm(skreq, ctx->enc);
        skcipher_request_set_callback(skreq, flags,
                                      req->base.complete, req->base.data);
-       skcipher_request_set_crypt(skreq, dst, dst, cryptlen, req->iv);
+       skcipher_request_set_crypt(skreq, src, dst, cryptlen, req->iv);
 
        return crypto_skcipher_decrypt(skreq);
 }
@@ -255,6 +260,7 @@ static int crypto_authenc_esn_decrypt(struct aead_request *req)
        unsigned int assoclen = req->assoclen;
        unsigned int cryptlen = req->cryptlen;
        u8 *ihash = ohash + crypto_ahash_digestsize(auth);
+       struct scatterlist *src = req->src;
        struct scatterlist *dst = req->dst;
        u32 tmp[2];
        int err;
@@ -262,24 +268,28 @@ static int crypto_authenc_esn_decrypt(struct aead_request *req)
        if (assoclen < 8)
                return -EINVAL;
 
-       cryptlen -= authsize;
-
-       if (req->src != dst)
-               memcpy_sglist(dst, req->src, assoclen + cryptlen);
+       if (!authsize)
+               goto tail;
 
+       cryptlen -= authsize;
        scatterwalk_map_and_copy(ihash, req->src, assoclen + cryptlen,
                                 authsize, 0);
 
-       if (!authsize)
-               goto tail;
-
        /* Move high-order bits of sequence number to the end. */
-       scatterwalk_map_and_copy(tmp, dst, 0, 8, 0);
-       scatterwalk_map_and_copy(tmp, dst, 4, 4, 1);
-       scatterwalk_map_and_copy(tmp + 1, dst, assoclen + cryptlen, 4, 1);
-
-       sg_init_table(areq_ctx->dst, 2);
-       dst = scatterwalk_ffwd(areq_ctx->dst, dst, 4);
+       scatterwalk_map_and_copy(tmp, src, 0, 8, 0);
+       if (src == dst) {
+               scatterwalk_map_and_copy(tmp, dst, 4, 4, 1);
+               scatterwalk_map_and_copy(tmp + 1, dst, assoclen + cryptlen, 4, 1);
+               dst = scatterwalk_ffwd(areq_ctx->dst, dst, 4);
+       } else {
+               scatterwalk_map_and_copy(tmp, dst, 0, 4, 1);
+               scatterwalk_map_and_copy(tmp + 1, dst, assoclen + cryptlen - 4, 4, 1);
+
+               src = scatterwalk_ffwd(areq_ctx->src, src, 8);
+               dst = scatterwalk_ffwd(areq_ctx->dst, dst, 4);
+               memcpy_sglist(dst, src, assoclen + cryptlen - 8);
+               dst = req->dst;
+       }
 
        ahash_request_set_tfm(ahreq, auth);
        ahash_request_set_crypt(ahreq, dst, ohash, assoclen + cryptlen);