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[173.164.112.133]) by smtp.gmail.com with ESMTPSA id 5-v6sm10969030pfd.11.2018.06.28.17.28.51 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 28 Jun 2018 17:28:53 -0700 (PDT) From: Kees Cook To: Herbert Xu Date: Thu, 28 Jun 2018 17:28:41 -0700 Message-Id: <20180629002843.31095-8-keescook@chromium.org> In-Reply-To: <20180629002843.31095-1-keescook@chromium.org> References: <20180629002843.31095-1-keescook@chromium.org> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Fri, 29 Jun 2018 00:28:57 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Fri, 29 Jun 2018 00:28:57 +0000 (UTC) for IP:'209.85.160.67' DOMAIN:'mail-pl0-f67.google.com' HELO:'mail-pl0-f67.google.com' FROM:'keescook@chromium.org' RCPT:'' X-RedHat-Spam-Score: -0.131 (DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H3, RCVD_IN_MSPIKE_WL, SPF_PASS) 209.85.160.67 mail-pl0-f67.google.com 209.85.160.67 mail-pl0-f67.google.com X-Scanned-By: MIMEDefang 2.78 on 10.5.110.30 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.25 X-loop: dm-devel@redhat.com Cc: Giovanni Cabiddu , Kees Cook , Arnd Bergmann , Eric Biggers , Mike Snitzer , "Gustavo A. R. Silva" , qat-linux@intel.com, linux-kernel@vger.kernel.org, dm-devel@redhat.com, linux-crypto@vger.kernel.org, Lars Persson , Tim Chen , "David S. Miller" , Alasdair Kergon , Rabin Vincent Subject: [dm-devel] [PATCH v3 7/9] crypto alg: Introduce generic max blocksize and alignmask X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.12 Precedence: junk List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.41]); Fri, 29 Jun 2018 00:30:27 +0000 (UTC) X-Virus-Scanned: ClamAV using ClamSMTP In the quest to remove all stack VLA usage from the kernel[1], this exposes a new general upper bound on crypto blocksize and alignmask (higher than for the existing cipher limits) for VLA removal, and introduces new checks. At present, the highest cra_alignmask in the kernel is 63. The highest cra_blocksize is 144 (SHA3_224_BLOCK_SIZE, 18 8-byte words). For the new blocksize limit, I went with 160 (20 8-byte words). [1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com Signed-off-by: Kees Cook --- crypto/algapi.c | 7 ++++++- include/crypto/algapi.h | 4 +++- 2 files changed, 9 insertions(+), 2 deletions(-) diff --git a/crypto/algapi.c b/crypto/algapi.c index c0755cf4f53f..496fc51bf215 100644 --- a/crypto/algapi.c +++ b/crypto/algapi.c @@ -57,9 +57,14 @@ static int crypto_check_alg(struct crypto_alg *alg) if (alg->cra_alignmask & (alg->cra_alignmask + 1)) return -EINVAL; - if (alg->cra_blocksize > PAGE_SIZE / 8) + /* General maximums for all algs. */ + if (alg->cra_alignmask > MAX_ALGAPI_ALIGNMASK) return -EINVAL; + if (alg->cra_blocksize > MAX_ALGAPI_BLOCKSIZE) + return -EINVAL; + + /* Lower maximums for specific alg types. */ if (!alg->cra_type && (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) == CRYPTO_ALG_TYPE_CIPHER) { if (alg->cra_alignmask > MAX_CIPHER_ALIGNMASK) diff --git a/include/crypto/algapi.h b/include/crypto/algapi.h index bd5e8ccf1687..21371ac8f355 100644 --- a/include/crypto/algapi.h +++ b/include/crypto/algapi.h @@ -20,8 +20,10 @@ /* * Maximum values for blocksize and alignmask, used to allocate * static buffers that are big enough for any combination of - * ciphers and architectures. + * algs and architectures. Ciphers have a lower maximum size. */ +#define MAX_ALGAPI_BLOCKSIZE 160 +#define MAX_ALGAPI_ALIGNMASK 63 #define MAX_CIPHER_BLOCKSIZE 16 #define MAX_CIPHER_ALIGNMASK 15