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From: Kees Cook <keescook@chromium.org>
To: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Kees Cook <keescook@chromium.org>, Arnd Bergmann <arnd@arndb.de>,
	Eric Biggers <ebiggers@google.com>,
	"Gustavo A. R. Silva" <gustavo@embeddedor.com>,
	Alasdair Kergon <agk@redhat.com>, Rabin Vincent <rabinv@axis.com>,
	Tim Chen <tim.c.chen@linux.intel.com>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Pavel Machek <pavel@ucw.cz>, Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	x86@kernel.org, Philipp Reisner <philipp.reisner@linbit.com>,
	Lars Ellenberg <lars.ellenberg@linbit.com>,
	Jens Axboe <axboe@kernel.dk>,
	Giovanni Cabiddu <giovanni.cabiddu@intel.com>,
	Mike Snitzer <snitzer@redhat.com>,
	Paul Mackerras <paulus@samba.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	David Howells <dhowells@redhat.com>,
	Johannes Berg <johannes@sipsolutions.net>,
	Tudor-Dan Ambarus <tudor.ambarus@microchip.com>,
	Jia-Ju Bai <baijiaju1990@gmail.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Geert Uytterhoeven <geert@linux-m68k.org>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	David Woodhouse <dwmw@amazon.co.uk>,
	Will Deacon <will.deacon@arm.com>,
	dm-devel@redhat.com, linux-pm@vger.kernel.org,
	linux-crypto@vger.kernel.org, drbd-dev@lists.linbit.com,
	linux-block@vger.kernel.org, qat-linux@intel.com,
	linux-ppp@vger.kernel.org, netdev@vger.kernel.org,
	devel@driverdev.osuosl.org, linux-afs@lists.infradead.org,
	linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v6 03/18] crypto: hash: Remove VLA usage
Date: Tue, 24 Jul 2018 16:49:21 +0000	[thread overview]
Message-ID: <20180724164936.37477-4-keescook@chromium.org> (raw)
In-Reply-To: <20180724164936.37477-1-keescook@chromium.org>

In the quest to remove all stack VLA usage from the kernel[1], this
removes the VLAs in SHASH_DESC_ON_STACK (via crypto_shash_descsize())
by using the maximum allowable size (which is now more clearly captured
in a macro), along with a few other cases. Similar limits are turned into
macros as well.

A review of existing sizes shows that SHA512_DIGEST_SIZE (64) is the
largest digest size and that sizeof(struct sha3_state) (360) is the
largest descriptor size. The corresponding maximums are reduced.

[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com

Signed-off-by: Kees Cook <keescook@chromium.org>
---
 crypto/ahash.c        | 4 ++--
 crypto/algif_hash.c   | 2 +-
 crypto/shash.c        | 6 +++---
 include/crypto/hash.h | 6 +++++-
 4 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/crypto/ahash.c b/crypto/ahash.c
index a64c143165b1..78aaf2158c43 100644
--- a/crypto/ahash.c
+++ b/crypto/ahash.c
@@ -550,8 +550,8 @@ static int ahash_prepare_alg(struct ahash_alg *alg)
 {
 	struct crypto_alg *base = &alg->halg.base;
 
-	if (alg->halg.digestsize > PAGE_SIZE / 8 ||
-	    alg->halg.statesize > PAGE_SIZE / 8 ||
+	if (alg->halg.digestsize > HASH_MAX_DIGESTSIZE ||
+	    alg->halg.statesize > HASH_MAX_STATESIZE ||
 	    alg->halg.statesize = 0)
 		return -EINVAL;
 
diff --git a/crypto/algif_hash.c b/crypto/algif_hash.c
index bfcf595fd8f9..d0cde541beb6 100644
--- a/crypto/algif_hash.c
+++ b/crypto/algif_hash.c
@@ -239,7 +239,7 @@ static int hash_accept(struct socket *sock, struct socket *newsock, int flags,
 	struct alg_sock *ask = alg_sk(sk);
 	struct hash_ctx *ctx = ask->private;
 	struct ahash_request *req = &ctx->req;
-	char state[crypto_ahash_statesize(crypto_ahash_reqtfm(req)) ? : 1];
+	char state[HASH_MAX_STATESIZE];
 	struct sock *sk2;
 	struct alg_sock *ask2;
 	struct hash_ctx *ctx2;
diff --git a/crypto/shash.c b/crypto/shash.c
index 5d732c6bb4b2..86d76b5c626c 100644
--- a/crypto/shash.c
+++ b/crypto/shash.c
@@ -458,9 +458,9 @@ static int shash_prepare_alg(struct shash_alg *alg)
 {
 	struct crypto_alg *base = &alg->base;
 
-	if (alg->digestsize > PAGE_SIZE / 8 ||
-	    alg->descsize > PAGE_SIZE / 8 ||
-	    alg->statesize > PAGE_SIZE / 8)
+	if (alg->digestsize > HASH_MAX_DIGESTSIZE ||
+	    alg->descsize > HASH_MAX_DESCSIZE ||
+	    alg->statesize > HASH_MAX_STATESIZE)
 		return -EINVAL;
 
 	base->cra_type = &crypto_shash_type;
diff --git a/include/crypto/hash.h b/include/crypto/hash.h
index 76e432cab75d..21587011ab0f 100644
--- a/include/crypto/hash.h
+++ b/include/crypto/hash.h
@@ -151,9 +151,13 @@ struct shash_desc {
 	void *__ctx[] CRYPTO_MINALIGN_ATTR;
 };
 
+#define HASH_MAX_DIGESTSIZE	 64
+#define HASH_MAX_DESCSIZE	360
+#define HASH_MAX_STATESIZE	512
+
 #define SHASH_DESC_ON_STACK(shash, ctx)				  \
 	char __##shash##_desc[sizeof(struct shash_desc) +	  \
-		crypto_shash_descsize(ctx)] CRYPTO_MINALIGN_ATTR; \
+		HASH_MAX_DESCSIZE] CRYPTO_MINALIGN_ATTR; \
 	struct shash_desc *shash = (struct shash_desc *)__##shash##_desc
 
 /**
-- 
2.17.1


  parent reply	other threads:[~2018-07-24 16:49 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-24 16:49 [PATCH v6 00/18] crypto: " Kees Cook
2018-07-24 16:49 ` [PATCH v6 01/18] crypto: xcbc: " Kees Cook
2018-07-24 16:49 ` [PATCH v6 02/18] crypto: cbc: " Kees Cook
2018-07-24 16:49 ` Kees Cook [this message]
2018-07-24 16:49 ` [PATCH v6 04/18] dm: Remove VLA usage from hashes Kees Cook
2018-07-24 16:49 ` [PATCH v6 05/18] crypto alg: Introduce generic max blocksize and alignmask Kees Cook
2018-07-24 16:49 ` [PATCH v6 06/18] crypto: qat: Remove VLA usage Kees Cook
2018-07-24 16:49 ` [PATCH v6 07/18] crypto: shash: Remove VLA usage in unaligned hashing Kees Cook
2018-07-24 16:49 ` [PATCH v6 08/18] crypto: skcipher: Remove VLA usage for SKCIPHER_REQUEST_ON_STACK Kees Cook
2018-07-24 16:49 ` [PATCH v6 09/18] ppp: mppe: Remove VLA usage Kees Cook
2018-07-24 16:49 ` [PATCH v6 10/18] x86/power/64: " Kees Cook
2018-07-25 11:32   ` Rafael J. Wysocki
2018-07-25 18:01     ` Kees Cook
2018-08-06 10:28       ` Rafael J. Wysocki
2018-07-24 16:49 ` [PATCH v6 11/18] dm crypt: Convert essiv from ahash to shash Kees Cook
2018-07-24 16:49 ` [PATCH v6 12/18] drbd: Convert " Kees Cook
2018-07-24 16:49 ` [PATCH v6 13/18] wireless/lib80211: " Kees Cook
2018-07-25  7:24   ` Johannes Berg
2018-07-24 16:49 ` [PATCH v6 14/18] staging: rtl8192u: ieee80211: " Kees Cook
2018-07-24 16:49 ` [PATCH v6 15/18] staging: rtl8192e: " Kees Cook
2018-07-24 16:49 ` [PATCH v6 16/18] rxrpc: Reuse SKCIPHER_REQUEST_ON_STACK buffer Kees Cook
2018-07-24 16:49 ` [PATCH v6 17/18] crypto: ccm: Remove VLA usage Kees Cook
2018-07-24 16:57   ` Ard Biesheuvel
2018-07-24 17:51     ` Kees Cook
2018-07-24 16:49 ` [PATCH v6 18/18] crypto: Remove AHASH_REQUEST_ON_STACK Kees Cook
2018-07-24 17:31   ` Joe Perches
2018-07-24 17:53     ` Kees Cook

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