From 6a99d7a2d73cbeaa0b93551fc8ec887295821bbe Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Tue, 7 Jul 2020 09:31:53 +0300 Subject: [PATCH] crypto: omap-aes - permit asynchronous skcipher as fallback Even though the omap-aes driver implements asynchronous versions of ecb(aes), cbc(aes) and ctr(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 Signed-off-by: Herbert Xu --- drivers/crypto/omap-aes.c | 35 +++++++++++++++++------------------ drivers/crypto/omap-aes.h | 3 ++- 2 files changed, 19 insertions(+), 19 deletions(-) diff --git a/drivers/crypto/omap-aes.c b/drivers/crypto/omap-aes.c index b5aff20..25154b7 100644 --- a/drivers/crypto/omap-aes.c +++ b/drivers/crypto/omap-aes.c @@ -548,20 +548,18 @@ static int omap_aes_crypt(struct skcipher_request *req, unsigned long mode) !!(mode & FLAGS_CBC)); if (req->cryptlen < aes_fallback_sz) { - SYNC_SKCIPHER_REQUEST_ON_STACK(subreq, ctx->fallback); - - 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, - req->cryptlen, req->iv); + 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 (mode & FLAGS_ENCRYPT) - 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; } dd = omap_aes_find_dev(rctx); @@ -590,11 +588,11 @@ static int omap_aes_setkey(struct crypto_skcipher *tfm, const u8 *key, memcpy(ctx->key, key, keylen); ctx->keylen = keylen; - crypto_sync_skcipher_clear_flags(ctx->fallback, CRYPTO_TFM_REQ_MASK); - crypto_sync_skcipher_set_flags(ctx->fallback, tfm->base.crt_flags & + crypto_skcipher_clear_flags(ctx->fallback, CRYPTO_TFM_REQ_MASK); + crypto_skcipher_set_flags(ctx->fallback, tfm->base.crt_flags & CRYPTO_TFM_REQ_MASK); - ret = crypto_sync_skcipher_setkey(ctx->fallback, key, keylen); + ret = crypto_skcipher_setkey(ctx->fallback, key, keylen); if (!ret) return 0; @@ -640,15 +638,16 @@ static int omap_aes_init_tfm(struct crypto_skcipher *tfm) { const char *name = crypto_tfm_alg_name(&tfm->base); struct omap_aes_ctx *ctx = 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); ctx->fallback = blk; - crypto_skcipher_set_reqsize(tfm, sizeof(struct omap_aes_reqctx)); + crypto_skcipher_set_reqsize(tfm, sizeof(struct omap_aes_reqctx) + + crypto_skcipher_reqsize(blk)); ctx->enginectx.op.prepare_request = omap_aes_prepare_req; ctx->enginectx.op.unprepare_request = NULL; @@ -662,7 +661,7 @@ static void omap_aes_exit_tfm(struct crypto_skcipher *tfm) struct omap_aes_ctx *ctx = crypto_skcipher_ctx(tfm); if (ctx->fallback) - crypto_free_sync_skcipher(ctx->fallback); + crypto_free_skcipher(ctx->fallback); ctx->fallback = NULL; } diff --git a/drivers/crypto/omap-aes.h b/drivers/crypto/omap-aes.h index 2d111bf..23d073e 100644 --- a/drivers/crypto/omap-aes.h +++ b/drivers/crypto/omap-aes.h @@ -97,7 +97,7 @@ struct omap_aes_ctx { int keylen; u32 key[AES_KEYSIZE_256 / sizeof(u32)]; u8 nonce[4]; - struct crypto_sync_skcipher *fallback; + struct crypto_skcipher *fallback; }; struct omap_aes_gcm_ctx { @@ -110,6 +110,7 @@ struct omap_aes_reqctx { unsigned long mode; u8 iv[AES_BLOCK_SIZE]; u32 auth_tag[AES_BLOCK_SIZE / sizeof(u32)]; + struct skcipher_request fallback_req; // keep at the end }; #define OMAP_AES_QUEUE_LENGTH 1 -- 2.7.4