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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 09/18] ppp: mppe: Remove VLA usage
Date: Tue, 24 Jul 2018 16:49:27 +0000	[thread overview]
Message-ID: <20180724164936.37477-10-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 discouraged use of AHASH_REQUEST_ON_STACK (and associated
VLA) by switching to shash directly and keeping the associated descriptor
allocated with the regular state on the heap.

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

Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/net/ppp/ppp_mppe.c | 56 ++++++++++++++++++++------------------
 1 file changed, 30 insertions(+), 26 deletions(-)

diff --git a/drivers/net/ppp/ppp_mppe.c b/drivers/net/ppp/ppp_mppe.c
index 6c7fd98cb00a..a205750b431b 100644
--- a/drivers/net/ppp/ppp_mppe.c
+++ b/drivers/net/ppp/ppp_mppe.c
@@ -96,7 +96,7 @@ static inline void sha_pad_init(struct sha_pad *shapad)
  */
 struct ppp_mppe_state {
 	struct crypto_skcipher *arc4;
-	struct crypto_ahash *sha1;
+	struct shash_desc *sha1;
 	unsigned char *sha1_digest;
 	unsigned char master_key[MPPE_MAX_KEY_LEN];
 	unsigned char session_key[MPPE_MAX_KEY_LEN];
@@ -136,25 +136,16 @@ struct ppp_mppe_state {
  */
 static void get_new_key_from_sha(struct ppp_mppe_state * state)
 {
-	AHASH_REQUEST_ON_STACK(req, state->sha1);
-	struct scatterlist sg[4];
-	unsigned int nbytes;
-
-	sg_init_table(sg, 4);
-
-	nbytes = setup_sg(&sg[0], state->master_key, state->keylen);
-	nbytes += setup_sg(&sg[1], sha_pad->sha_pad1,
-			   sizeof(sha_pad->sha_pad1));
-	nbytes += setup_sg(&sg[2], state->session_key, state->keylen);
-	nbytes += setup_sg(&sg[3], sha_pad->sha_pad2,
-			   sizeof(sha_pad->sha_pad2));
-
-	ahash_request_set_tfm(req, state->sha1);
-	ahash_request_set_callback(req, 0, NULL, NULL);
-	ahash_request_set_crypt(req, sg, state->sha1_digest, nbytes);
-
-	crypto_ahash_digest(req);
-	ahash_request_zero(req);
+	crypto_shash_init(state->sha1);
+	crypto_shash_update(state->sha1, state->master_key,
+			    state->keylen);
+	crypto_shash_update(state->sha1, sha_pad->sha_pad1,
+			    sizeof(sha_pad->sha_pad1));
+	crypto_shash_update(state->sha1, state->session_key,
+			    state->keylen);
+	crypto_shash_update(state->sha1, sha_pad->sha_pad2,
+			    sizeof(sha_pad->sha_pad2));
+	crypto_shash_final(state->sha1, state->sha1_digest);
 }
 
 /*
@@ -200,6 +191,7 @@ static void mppe_rekey(struct ppp_mppe_state * state, int initial_key)
 static void *mppe_alloc(unsigned char *options, int optlen)
 {
 	struct ppp_mppe_state *state;
+	struct crypto_shash *shash;
 	unsigned int digestsize;
 
 	if (optlen != CILEN_MPPE + sizeof(state->master_key) ||
@@ -217,13 +209,21 @@ static void *mppe_alloc(unsigned char *options, int optlen)
 		goto out_free;
 	}
 
-	state->sha1 = crypto_alloc_ahash("sha1", 0, CRYPTO_ALG_ASYNC);
-	if (IS_ERR(state->sha1)) {
-		state->sha1 = NULL;
+	shash = crypto_alloc_shash("sha1", 0, 0);
+	if (IS_ERR(shash))
+		goto out_free;
+
+	state->sha1 = kmalloc(sizeof(*state->sha1) +
+				     crypto_shash_descsize(shash),
+			      GFP_KERNEL);
+	if (!state->sha1) {
+		crypto_free_shash(shash);
 		goto out_free;
 	}
+	state->sha1->tfm = shash;
+	state->sha1->flags = 0;
 
-	digestsize = crypto_ahash_digestsize(state->sha1);
+	digestsize = crypto_shash_digestsize(shash);
 	if (digestsize < MPPE_MAX_KEY_LEN)
 		goto out_free;
 
@@ -246,7 +246,10 @@ static void *mppe_alloc(unsigned char *options, int optlen)
 
 out_free:
 	kfree(state->sha1_digest);
-	crypto_free_ahash(state->sha1);
+	if (state->sha1) {
+		crypto_free_shash(state->sha1->tfm);
+		kzfree(state->sha1);
+	}
 	crypto_free_skcipher(state->arc4);
 	kfree(state);
 out:
@@ -261,7 +264,8 @@ static void mppe_free(void *arg)
 	struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
 	if (state) {
 		kfree(state->sha1_digest);
-		crypto_free_ahash(state->sha1);
+		crypto_free_shash(state->sha1->tfm);
+		kzfree(state->sha1);
 		crypto_free_skcipher(state->arc4);
 		kfree(state);
 	}
-- 
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 ` [PATCH v6 03/18] crypto: hash: " Kees Cook
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 ` Kees Cook [this message]
2018-07-24 16:49 ` [PATCH v6 10/18] x86/power/64: Remove VLA usage 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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