From: Kees Cook <keescook@chromium.org>
To: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Kees Cook <keescook@chromium.org>,
"Gustavo A. R. Silva" <gustavo@embeddedor.com>,
Arnd Bergmann <arnd@arndb.de>, Eric Biggers <ebiggers@google.com>,
Alasdair Kergon <agk@redhat.com>,
Giovanni Cabiddu <giovanni.cabiddu@intel.com>,
Lars Persson <larper@axis.com>, Mike Snitzer <snitzer@redhat.com>,
Rabin Vincent <rabinv@axis.com>,
Tim Chen <tim.c.chen@linux.intel.com>,
"David S. Miller" <davem@davemloft.net>,
linux-crypto@vger.kernel.org, qat-linux@intel.com,
dm-devel@redhat.com, linux-kernel@vger.kernel.org
Subject: [PATCH v3 7/9] crypto alg: Introduce generic max blocksize and alignmask
Date: Thu, 28 Jun 2018 17:28:41 -0700 [thread overview]
Message-ID: <20180629002843.31095-8-keescook@chromium.org> (raw)
In-Reply-To: <20180629002843.31095-1-keescook@chromium.org>
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 <keescook@chromium.org>
---
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
--
2.17.1
next prev parent reply other threads:[~2018-06-29 0:29 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-29 0:28 [PATCH v3 0/9] Crypto: Remove VLA usage (part 1) Kees Cook
2018-06-29 0:28 ` [PATCH v3 1/9] crypto: xcbc: Remove VLA usage Kees Cook
2018-06-29 0:28 ` [PATCH v3 2/9] crypto: cbc: " Kees Cook
2018-06-29 0:28 ` [PATCH v3 3/9] crypto: shash: " Kees Cook
2018-06-29 0:28 ` [PATCH v3 4/9] dm integrity: " Kees Cook
2018-06-29 20:43 ` Arnd Bergmann
2018-06-29 21:56 ` Kees Cook
2018-07-01 6:29 ` Herbert Xu
2018-06-29 0:28 ` [PATCH v3 5/9] crypto: ahash: " Kees Cook
2018-06-29 0:28 ` [PATCH v3 6/9] dm verity fec: " Kees Cook
2018-06-29 0:28 ` Kees Cook [this message]
2018-06-29 0:28 ` [PATCH v3 8/9] crypto: qat: " Kees Cook
2018-06-29 0:28 ` [PATCH v3 9/9] crypto: shash: Remove VLA usage in unaligned hashing Kees Cook
2018-06-30 7:03 ` [dm-devel] " Eric Biggers
2018-07-01 17:04 ` Kees Cook
2018-07-01 17:20 ` Eric Biggers
2018-07-02 17:34 ` Kees Cook
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