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>,
Masahiro Yamada <yamada.masahiro@socionext.com>,
linux-crypto@vger.kernel.org, qat-linux@intel.com,
dm-devel@redhat.com, linux-kernel@vger.kernel.org
Subject: [PATCH v4 09/14] crypto: shash: Remove VLA usage in unaligned hashing
Date: Wed, 11 Jul 2018 13:36:14 -0700 [thread overview]
Message-ID: <20180711203619.1020-10-keescook@chromium.org> (raw)
In-Reply-To: <20180711203619.1020-1-keescook@chromium.org>
In the quest to remove all stack VLA usage from the kernel[1], this uses
the newly defined max alignment to perform unaligned hashing to avoid
VLAs, and drops the helper function while adding sanity checks on the
resulting buffer sizes. Additionally, the __aligned_largest macro is
removed since this helper was the only user.
[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com
Signed-off-by: Kees Cook <keescook@chromium.org>
---
crypto/shash.c | 27 ++++++++++++++++-----------
include/linux/compiler-gcc.h | 1 -
2 files changed, 16 insertions(+), 12 deletions(-)
diff --git a/crypto/shash.c b/crypto/shash.c
index ab6902c6dae7..8d4746b14dd5 100644
--- a/crypto/shash.c
+++ b/crypto/shash.c
@@ -73,13 +73,6 @@ int crypto_shash_setkey(struct crypto_shash *tfm, const u8 *key,
}
EXPORT_SYMBOL_GPL(crypto_shash_setkey);
-static inline unsigned int shash_align_buffer_size(unsigned len,
- unsigned long mask)
-{
- typedef u8 __aligned_largest u8_aligned;
- return len + (mask & ~(__alignof__(u8_aligned) - 1));
-}
-
static int shash_update_unaligned(struct shash_desc *desc, const u8 *data,
unsigned int len)
{
@@ -88,11 +81,17 @@ static int shash_update_unaligned(struct shash_desc *desc, const u8 *data,
unsigned long alignmask = crypto_shash_alignmask(tfm);
unsigned int unaligned_len = alignmask + 1 -
((unsigned long)data & alignmask);
- u8 ubuf[shash_align_buffer_size(unaligned_len, alignmask)]
- __aligned_largest;
+ /*
+ * We cannot count on __aligned() working for large values:
+ * https://patchwork.kernel.org/patch/9507697/
+ */
+ u8 ubuf[MAX_ALGAPI_ALIGNMASK * 2];
u8 *buf = PTR_ALIGN(&ubuf[0], alignmask + 1);
int err;
+ if (WARN_ON(buf + unaligned_len > ubuf + sizeof(ubuf)))
+ return -EINVAL;
+
if (unaligned_len > len)
unaligned_len = len;
@@ -124,11 +123,17 @@ static int shash_final_unaligned(struct shash_desc *desc, u8 *out)
unsigned long alignmask = crypto_shash_alignmask(tfm);
struct shash_alg *shash = crypto_shash_alg(tfm);
unsigned int ds = crypto_shash_digestsize(tfm);
- u8 ubuf[shash_align_buffer_size(ds, alignmask)]
- __aligned_largest;
+ /*
+ * We cannot count on __aligned() working for large values:
+ * https://patchwork.kernel.org/patch/9507697/
+ */
+ u8 ubuf[MAX_ALGAPI_ALIGNMASK + SHASH_MAX_DIGESTSIZE];
u8 *buf = PTR_ALIGN(&ubuf[0], alignmask + 1);
int err;
+ if (WARN_ON(buf + ds > ubuf + sizeof(ubuf)))
+ return -EINVAL;
+
err = shash->final(desc, buf);
if (err)
goto out;
diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
index f1a7492a5cc8..1f1cdef36a82 100644
--- a/include/linux/compiler-gcc.h
+++ b/include/linux/compiler-gcc.h
@@ -125,7 +125,6 @@
*/
#define __pure __attribute__((pure))
#define __aligned(x) __attribute__((aligned(x)))
-#define __aligned_largest __attribute__((aligned))
#define __printf(a, b) __attribute__((format(printf, a, b)))
#define __scanf(a, b) __attribute__((format(scanf, a, b)))
#define __attribute_const__ __attribute__((__const__))
--
2.17.1
next prev parent reply other threads:[~2018-07-11 20:36 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-11 20:36 [PATCH v4 00/14] crypto: Remove VLA usage Kees Cook
2018-07-11 20:36 ` [PATCH v4 01/14] crypto: xcbc: " Kees Cook
2018-07-11 20:36 ` [PATCH v4 02/14] crypto: cbc: " Kees Cook
2018-07-11 20:36 ` [PATCH v4 03/14] crypto: shash: " Kees Cook
2018-07-11 20:36 ` [PATCH v4 04/14] dm integrity: " Kees Cook
2018-07-11 20:36 ` [PATCH v4 05/14] crypto: ahash: " Kees Cook
2018-07-11 20:36 ` [PATCH v4 06/14] dm verity fec: " Kees Cook
2018-07-11 20:36 ` [PATCH v4 07/14] crypto alg: Introduce generic max blocksize and alignmask Kees Cook
2018-07-11 20:36 ` [PATCH v4 08/14] crypto: qat: Remove VLA usage Kees Cook
2018-07-11 20:36 ` Kees Cook [this message]
2018-07-11 20:36 ` [PATCH v4 10/14] kbuild: Introduce FRAME_WARN_BUMP_FLAG Kees Cook
2018-07-11 20:36 ` [PATCH v4 11/14] treewide: Prepare to remove VLA usage for AHASH_REQUEST_ON_STACK Kees Cook
2018-07-12 16:02 ` Arnd Bergmann
2018-07-12 20:17 ` Kees Cook
2018-07-12 21:38 ` Arnd Bergmann
2018-07-13 0:40 ` Herbert Xu
2018-07-13 3:33 ` Kees Cook
2018-07-13 3:44 ` Herbert Xu
2018-07-13 5:17 ` Kees Cook
2018-07-13 5:20 ` Herbert Xu
2018-07-13 6:00 ` Kees Cook
2018-07-13 10:14 ` Arnd Bergmann
2018-07-15 4:28 ` Kees Cook
2018-07-17 20:59 ` Arnd Bergmann
2018-07-18 14:50 ` Ard Biesheuvel
2018-07-18 15:19 ` Ard Biesheuvel
2018-07-18 15:33 ` Arnd Bergmann
2018-07-18 15:33 ` Ard Biesheuvel
2018-07-19 2:51 ` Kees Cook
2018-07-19 2:55 ` Ard Biesheuvel
2018-07-19 3:09 ` Kees Cook
2018-07-19 3:13 ` Ard Biesheuvel
2018-07-19 14:54 ` Ard Biesheuvel
2018-07-19 18:44 ` Kees Cook
2018-07-13 6:16 ` Kees Cook
2018-07-13 6:22 ` Herbert Xu
2018-07-14 3:07 ` Kees Cook
2018-07-15 2:44 ` Herbert Xu
2018-07-15 2:59 ` Kees Cook
2018-07-16 0:01 ` Herbert Xu
2018-07-16 3:39 ` Kees Cook
2018-07-16 7:24 ` Arnd Bergmann
2018-07-11 20:36 ` [PATCH v4 12/14] crypto: ahash: Remove " Kees Cook
2018-07-11 20:36 ` [PATCH v4 13/14] rxrpc: Prepare to remove VLA usage for SKCIPHER_REQUEST_ON_STACK Kees Cook
2018-07-12 15:11 ` Arnd Bergmann
2018-07-12 20:23 ` Kees Cook
2018-07-12 20:30 ` Kees Cook
2018-07-12 21:15 ` Arnd Bergmann
2018-07-12 21:38 ` Kees Cook
2018-07-12 21:28 ` David Howells
2018-07-12 21:34 ` Kees Cook
2018-07-12 22:05 ` David Howells
2018-07-11 20:36 ` [PATCH v4 14/14] crypto: skcipher: Remove " Kees Cook
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