From c9598d4e13ca0a6747235257a8e38cdef6973d8e Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Tue, 7 Jul 2020 09:31:59 +0300 Subject: crypto: mxs-dcp - permit asynchronous skcipher as fallback Even though the mxs-dcp driver implements asynchronous versions of ecb(aes) and cbc(aes), the fallbacks it allocates are required to be synchronous. Given that SIMD based software implementations are usually asynchronous as well, even though they rarely complete asynchronously (this typically only happens in cases where the request was made from softirq context, while SIMD was already in use in the task context that it interrupted), these implementations are disregarded, and either the generic C version or another table based version implemented in assembler is selected instead. Since falling back to synchronous AES is not only a performance issue, but potentially a security issue as well (due to the fact that table based AES is not time invariant), let's fix this, by allocating an ordinary skcipher as the fallback, and invoke it with the completion routine that was given to the outer request. Signed-off-by: Ard Biesheuvel Reviewed-by: Horia Geantă Signed-off-by: Herbert Xu --- drivers/crypto/mxs-dcp.c | 33 +++++++++++++++++---------------- 1 file changed, 17 insertions(+), 16 deletions(-) (limited to 'drivers/crypto') diff --git a/drivers/crypto/mxs-dcp.c b/drivers/crypto/mxs-dcp.c index d84530293036..909a7eb748e3 100644 --- a/drivers/crypto/mxs-dcp.c +++ b/drivers/crypto/mxs-dcp.c @@ -97,7 +97,7 @@ struct dcp_async_ctx { unsigned int hot:1; /* Crypto-specific context */ - struct crypto_sync_skcipher *fallback; + struct crypto_skcipher *fallback; unsigned int key_len; uint8_t key[AES_KEYSIZE_128]; }; @@ -105,6 +105,7 @@ struct dcp_async_ctx { struct dcp_aes_req_ctx { unsigned int enc:1; unsigned int ecb:1; + struct skcipher_request fallback_req; // keep at the end }; struct dcp_sha_req_ctx { @@ -426,21 +427,20 @@ static int dcp_chan_thread_aes(void *data) static int mxs_dcp_block_fallback(struct skcipher_request *req, int enc) { struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); + struct dcp_aes_req_ctx *rctx = skcipher_request_ctx(req); struct dcp_async_ctx *ctx = crypto_skcipher_ctx(tfm); - SYNC_SKCIPHER_REQUEST_ON_STACK(subreq, ctx->fallback); int ret; - skcipher_request_set_sync_tfm(subreq, ctx->fallback); - skcipher_request_set_callback(subreq, req->base.flags, NULL, NULL); - skcipher_request_set_crypt(subreq, req->src, req->dst, + skcipher_request_set_tfm(&rctx->fallback_req, ctx->fallback); + skcipher_request_set_callback(&rctx->fallback_req, req->base.flags, + req->base.complete, req->base.data); + skcipher_request_set_crypt(&rctx->fallback_req, req->src, req->dst, req->cryptlen, req->iv); if (enc) - ret = crypto_skcipher_encrypt(subreq); + ret = crypto_skcipher_encrypt(&rctx->fallback_req); else - ret = crypto_skcipher_decrypt(subreq); - - skcipher_request_zero(subreq); + ret = crypto_skcipher_decrypt(&rctx->fallback_req); return ret; } @@ -510,24 +510,25 @@ static int mxs_dcp_aes_setkey(struct crypto_skcipher *tfm, const u8 *key, * but is supported by in-kernel software implementation, we use * software fallback. */ - crypto_sync_skcipher_clear_flags(actx->fallback, CRYPTO_TFM_REQ_MASK); - crypto_sync_skcipher_set_flags(actx->fallback, + crypto_skcipher_clear_flags(actx->fallback, CRYPTO_TFM_REQ_MASK); + crypto_skcipher_set_flags(actx->fallback, tfm->base.crt_flags & CRYPTO_TFM_REQ_MASK); - return crypto_sync_skcipher_setkey(actx->fallback, key, len); + return crypto_skcipher_setkey(actx->fallback, key, len); } static int mxs_dcp_aes_fallback_init_tfm(struct crypto_skcipher *tfm) { const char *name = crypto_tfm_alg_name(crypto_skcipher_tfm(tfm)); struct dcp_async_ctx *actx = crypto_skcipher_ctx(tfm); - struct crypto_sync_skcipher *blk; + struct crypto_skcipher *blk; - blk = crypto_alloc_sync_skcipher(name, 0, CRYPTO_ALG_NEED_FALLBACK); + blk = crypto_alloc_skcipher(name, 0, CRYPTO_ALG_NEED_FALLBACK); if (IS_ERR(blk)) return PTR_ERR(blk); actx->fallback = blk; - crypto_skcipher_set_reqsize(tfm, sizeof(struct dcp_aes_req_ctx)); + crypto_skcipher_set_reqsize(tfm, sizeof(struct dcp_aes_req_ctx) + + crypto_skcipher_reqsize(blk)); return 0; } @@ -535,7 +536,7 @@ static void mxs_dcp_aes_fallback_exit_tfm(struct crypto_skcipher *tfm) { struct dcp_async_ctx *actx = crypto_skcipher_ctx(tfm); - crypto_free_sync_skcipher(actx->fallback); + crypto_free_skcipher(actx->fallback); } /* -- cgit v1.2.3