From patchwork Thu Feb 2 08:33:47 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Herbert Xu X-Patchwork-Id: 650399 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D3CBFC61DA4 for ; Thu, 2 Feb 2023 08:35:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231899AbjBBIfL (ORCPT ); Thu, 2 Feb 2023 03:35:11 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50722 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230208AbjBBIfJ (ORCPT ); Thu, 2 Feb 2023 03:35:09 -0500 Received: from formenos.hmeau.com (helcar.hmeau.com [216.24.177.18]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D061D5EF9A; Thu, 2 Feb 2023 00:34:25 -0800 (PST) Received: from loth.rohan.me.apana.org.au ([192.168.167.2]) by formenos.hmeau.com with smtp (Exim 4.94.2 #2 (Debian)) id 1pNV2R-006fJr-NT; Thu, 02 Feb 2023 16:33:48 +0800 Received: by loth.rohan.me.apana.org.au (sSMTP sendmail emulation); Thu, 02 Feb 2023 16:33:47 +0800 Date: Thu, 2 Feb 2023 16:33:47 +0800 From: Herbert Xu To: Tianjia Zhang Cc: "David S. Miller" , Catalin Marinas , Will Deacon , linux-crypto@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [v4 PATCH] crypto: arm64/sm4-gcm - Fix possible crash in GCM cryption Message-ID: References: <20230201123133.99768-1-tianjia.zhang@linux.alibaba.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20230201123133.99768-1-tianjia.zhang@linux.alibaba.com> Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org On Wed, Feb 01, 2023 at 08:31:33PM +0800, Tianjia Zhang wrote: > > + sm4_ce_pmull_gcm_crypt(ctx->key.rkey_enc, walk->dst.virt.addr, > + walk->src.virt.addr, iv, walk->nbytes, ghash, > + ctx->ghash_table, (const u8 *)&lengths); I still think this is error-prone. When walk->nbytes == 0, walk->src and walk->dst are undefined. Sure you could argue that the underlying assembly code won't touch the values, but accessing uninitialised memory even if just to throw them away is still a bit icky. Anyway, here's my attempt at rewriting the gcm loop: ---8<--- An often overlooked aspect of the skcipher walker API is that an error is not just indicated by a non-zero return value, but by the fact that walk->nbytes is zero. Thus it is an error to call skcipher_walk_done after getting back walk->nbytes == 0 from the previous interaction with the walker. This is because when walk->nbytes is zero the walker is left in an undefined state and any further calls to it may try to free uninitialised stack memory. The sm4 arm64 ccm code gets this wrong and ends up calling skcipher_walk_done even when walk->nbytes is zero. This patch rewrites the loop in a form that resembles other callers. Reported-by: Tianjia Zhang Fixes: ae1b83c7d572 ("crypto: arm64/sm4 - add CE implementation for GCM mode") Signed-off-by: Herbert Xu Tested-by: Tianjia Zhang diff --git a/arch/arm64/crypto/sm4-ce-gcm-glue.c b/arch/arm64/crypto/sm4-ce-gcm-glue.c index c450a2025ca9..73bfb6972d3a 100644 --- a/arch/arm64/crypto/sm4-ce-gcm-glue.c +++ b/arch/arm64/crypto/sm4-ce-gcm-glue.c @@ -135,22 +135,23 @@ static void gcm_calculate_auth_mac(struct aead_request *req, u8 ghash[]) } static int gcm_crypt(struct aead_request *req, struct skcipher_walk *walk, - struct sm4_gcm_ctx *ctx, u8 ghash[], + u8 ghash[], int err, void (*sm4_ce_pmull_gcm_crypt)(const u32 *rkey_enc, u8 *dst, const u8 *src, u8 *iv, unsigned int nbytes, u8 *ghash, const u8 *ghash_table, const u8 *lengths)) { + struct crypto_aead *aead = crypto_aead_reqtfm(req); + struct sm4_gcm_ctx *ctx = crypto_aead_ctx(aead); u8 __aligned(8) iv[SM4_BLOCK_SIZE]; be128 __aligned(8) lengths; - int err; memset(ghash, 0, SM4_BLOCK_SIZE); lengths.a = cpu_to_be64(req->assoclen * 8); lengths.b = cpu_to_be64(walk->total * 8); - memcpy(iv, walk->iv, GCM_IV_SIZE); + memcpy(iv, req->iv, GCM_IV_SIZE); put_unaligned_be32(2, iv + GCM_IV_SIZE); kernel_neon_begin(); @@ -158,49 +159,51 @@ static int gcm_crypt(struct aead_request *req, struct skcipher_walk *walk, if (req->assoclen) gcm_calculate_auth_mac(req, ghash); - do { + while (walk->nbytes) { unsigned int tail = walk->nbytes % SM4_BLOCK_SIZE; const u8 *src = walk->src.virt.addr; u8 *dst = walk->dst.virt.addr; if (walk->nbytes == walk->total) { - tail = 0; - sm4_ce_pmull_gcm_crypt(ctx->key.rkey_enc, dst, src, iv, walk->nbytes, ghash, ctx->ghash_table, (const u8 *)&lengths); - } else if (walk->nbytes - tail) { - sm4_ce_pmull_gcm_crypt(ctx->key.rkey_enc, dst, src, iv, - walk->nbytes - tail, ghash, - ctx->ghash_table, NULL); + + kernel_neon_end(); + + return skcipher_walk_done(walk, 0); } + sm4_ce_pmull_gcm_crypt(ctx->key.rkey_enc, dst, src, iv, + walk->nbytes - tail, ghash, + ctx->ghash_table, NULL); + kernel_neon_end(); err = skcipher_walk_done(walk, tail); - if (err) - return err; - if (walk->nbytes) - kernel_neon_begin(); - } while (walk->nbytes > 0); - return 0; + kernel_neon_begin(); + } + + sm4_ce_pmull_gcm_crypt(ctx->key.rkey_enc, NULL, NULL, iv, + walk->nbytes, ghash, ctx->ghash_table, + (const u8 *)&lengths); + + kernel_neon_end(); + + return err; } static int gcm_encrypt(struct aead_request *req) { struct crypto_aead *aead = crypto_aead_reqtfm(req); - struct sm4_gcm_ctx *ctx = crypto_aead_ctx(aead); u8 __aligned(8) ghash[SM4_BLOCK_SIZE]; struct skcipher_walk walk; int err; err = skcipher_walk_aead_encrypt(&walk, req, false); - if (err) - return err; - - err = gcm_crypt(req, &walk, ctx, ghash, sm4_ce_pmull_gcm_enc); + err = gcm_crypt(req, &walk, ghash, err, sm4_ce_pmull_gcm_enc); if (err) return err; @@ -215,17 +218,13 @@ static int gcm_decrypt(struct aead_request *req) { struct crypto_aead *aead = crypto_aead_reqtfm(req); unsigned int authsize = crypto_aead_authsize(aead); - struct sm4_gcm_ctx *ctx = crypto_aead_ctx(aead); u8 __aligned(8) ghash[SM4_BLOCK_SIZE]; u8 authtag[SM4_BLOCK_SIZE]; struct skcipher_walk walk; int err; err = skcipher_walk_aead_decrypt(&walk, req, false); - if (err) - return err; - - err = gcm_crypt(req, &walk, ctx, ghash, sm4_ce_pmull_gcm_dec); + err = gcm_crypt(req, &walk, ghash, err, sm4_ce_pmull_gcm_dec); if (err) return err;