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[173.164.112.133]) by smtp.gmail.com with ESMTPSA id b64-v6sm3357099pfg.66.2018.08.07.14.18.47 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 07 Aug 2018 14:18:50 -0700 (PDT) From: Kees Cook To: Herbert Xu Date: Tue, 7 Aug 2018 14:18:40 -0700 Message-Id: <20180807211843.47586-7-keescook@chromium.org> In-Reply-To: <20180807211843.47586-1-keescook@chromium.org> References: <20180807211843.47586-1-keescook@chromium.org> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.38]); Tue, 07 Aug 2018 21:18:53 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.38]); Tue, 07 Aug 2018 21:18:53 +0000 (UTC) for IP:'209.85.215.193' DOMAIN:'mail-pg1-f193.google.com' HELO:'mail-pg1-f193.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) 209.85.215.193 mail-pg1-f193.google.com 209.85.215.193 mail-pg1-f193.google.com X-Scanned-By: MIMEDefang 2.78 on 10.5.110.38 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-loop: dm-devel@redhat.com Cc: Giovanni Cabiddu , Matthew Wilcox , linux-kernel@vger.kernel.org, Kees Cook , Mike Snitzer , Ard Biesheuvel , Rasmus Villemoes , Eric Biggers , Will Deacon , qat-linux@intel.com, Arnd Bergmann , "David S. Miller" , "Gustavo A. R. Silva" , dm-devel@redhat.com, Geert Uytterhoeven , David Woodhouse , Tudor-Dan Ambarus , Andrew Morton , Thomas Gleixner , Alasdair Kergon , linux-crypto@vger.kernel.org Subject: [dm-devel] [PATCH v8 6/9] 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 10.5.11.25 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.43]); Tue, 07 Aug 2018 21:20:49 +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