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Date: Tue, 24 Jul 2018 09:49:27 -0700
From: Kees Cook <keescook@...omium.org>
To: Herbert Xu <herbert@...dor.apana.org.au>
Cc: Kees Cook <keescook@...omium.org>, Arnd Bergmann <arnd@...db.de>,
Eric Biggers <ebiggers@...gle.com>,
"Gustavo A. R. Silva" <gustavo@...eddedor.com>,
Alasdair Kergon <agk@...hat.com>,
Rabin Vincent <rabinv@...s.com>,
Tim Chen <tim.c.chen@...ux.intel.com>,
"Rafael J. Wysocki" <rjw@...ysocki.net>,
Pavel Machek <pavel@....cz>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
Philipp Reisner <philipp.reisner@...bit.com>,
Lars Ellenberg <lars.ellenberg@...bit.com>,
Jens Axboe <axboe@...nel.dk>,
Giovanni Cabiddu <giovanni.cabiddu@...el.com>,
Mike Snitzer <snitzer@...hat.com>,
Paul Mackerras <paulus@...ba.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
David Howells <dhowells@...hat.com>,
Johannes Berg <johannes@...solutions.net>,
Tudor-Dan Ambarus <tudor.ambarus@...rochip.com>,
Jia-Ju Bai <baijiaju1990@...il.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Geert Uytterhoeven <geert@...ux-m68k.org>,
Josh Poimboeuf <jpoimboe@...hat.com>,
David Woodhouse <dwmw@...zon.co.uk>,
Will Deacon <will.deacon@....com>, dm-devel@...hat.com,
linux-pm@...r.kernel.org, linux-crypto@...r.kernel.org,
drbd-dev@...ts.linbit.com, linux-block@...r.kernel.org,
qat-linux@...el.com, linux-ppp@...r.kernel.org,
netdev@...r.kernel.org, devel@...verdev.osuosl.org,
linux-afs@...ts.infradead.org, linux-wireless@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH v6 09/18] ppp: mppe: Remove VLA usage
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@...omium.org>
Acked-by: Arnd Bergmann <arnd@...db.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
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