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ppp: mppe: Remove VLA usage of skcipher

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In the quest to remove all stack VLA usage from the kernel[1], this
replaces struct crypto_skcipher and SKCIPHER_REQUEST_ON_STACK() usage
with struct crypto_sync_skcipher and SYNC_SKCIPHER_REQUEST_ON_STACK(),
which uses a fixed stack size.

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

Cc: Paul Mackerras <paulus@samba.org>
Cc: linux-ppp@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Kees Cook 2018-09-18 19:10:46 -07:00 committed by Herbert Xu
parent 69d6302b65
commit 82633a6f6d
1 changed files with 14 additions and 13 deletions
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27
drivers/net/ppp/ppp_mppe.c
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@ -95,7 +95,7 @@ static inline void sha_pad_init(struct sha_pad *shapad)
* State for an MPPE (de)compressor.
*/
struct ppp_mppe_state {
struct crypto_skcipher *arc4;
struct crypto_sync_skcipher *arc4;
struct shash_desc *sha1;
unsigned char *sha1_digest;
unsigned char master_key[MPPE_MAX_KEY_LEN];
@ -155,15 +155,15 @@ static void get_new_key_from_sha(struct ppp_mppe_state * state)
static void mppe_rekey(struct ppp_mppe_state * state, int initial_key)
{
struct scatterlist sg_in[1], sg_out[1];
SKCIPHER_REQUEST_ON_STACK(req, state->arc4);
SYNC_SKCIPHER_REQUEST_ON_STACK(req, state->arc4);
skcipher_request_set_tfm(req, state->arc4);
skcipher_request_set_sync_tfm(req, state->arc4);
skcipher_request_set_callback(req, 0, NULL, NULL);
get_new_key_from_sha(state);
if (!initial_key) {
crypto_skcipher_setkey(state->arc4, state->sha1_digest,
state->keylen);
crypto_sync_skcipher_setkey(state->arc4, state->sha1_digest,
state->keylen);
sg_init_table(sg_in, 1);
sg_init_table(sg_out, 1);
setup_sg(sg_in, state->sha1_digest, state->keylen);
@ -181,7 +181,8 @@ static void mppe_rekey(struct ppp_mppe_state * state, int initial_key)
state->session_key[1] = 0x26;
state->session_key[2] = 0x9e;
}
crypto_skcipher_setkey(state->arc4, state->session_key, state->keylen);
crypto_sync_skcipher_setkey(state->arc4, state->session_key,
state->keylen);
skcipher_request_zero(req);
}
@ -203,7 +204,7 @@ static void *mppe_alloc(unsigned char *options, int optlen)
goto out;
state->arc4 = crypto_alloc_skcipher("ecb(arc4)", 0, CRYPTO_ALG_ASYNC);
state->arc4 = crypto_alloc_sync_skcipher("ecb(arc4)", 0, 0);
if (IS_ERR(state->arc4)) {
state->arc4 = NULL;
goto out_free;
@ -250,7 +251,7 @@ out_free:
crypto_free_shash(state->sha1->tfm);
kzfree(state->sha1);
}
crypto_free_skcipher(state->arc4);
crypto_free_sync_skcipher(state->arc4);
kfree(state);
out:
return NULL;
@ -266,7 +267,7 @@ static void mppe_free(void *arg)
kfree(state->sha1_digest);
crypto_free_shash(state->sha1->tfm);
kzfree(state->sha1);
crypto_free_skcipher(state->arc4);
crypto_free_sync_skcipher(state->arc4);
kfree(state);
}
}
@ -366,7 +367,7 @@ mppe_compress(void *arg, unsigned char *ibuf, unsigned char *obuf,
int isize, int osize)
{
struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
SKCIPHER_REQUEST_ON_STACK(req, state->arc4);
SYNC_SKCIPHER_REQUEST_ON_STACK(req, state->arc4);
int proto;
int err;
struct scatterlist sg_in[1], sg_out[1];
@ -426,7 +427,7 @@ mppe_compress(void *arg, unsigned char *ibuf, unsigned char *obuf,
setup_sg(sg_in, ibuf, isize);
setup_sg(sg_out, obuf, osize);
skcipher_request_set_tfm(req, state->arc4);
skcipher_request_set_sync_tfm(req, state->arc4);
skcipher_request_set_callback(req, 0, NULL, NULL);
skcipher_request_set_crypt(req, sg_in, sg_out, isize, NULL);
err = crypto_skcipher_encrypt(req);
@ -480,7 +481,7 @@ mppe_decompress(void *arg, unsigned char *ibuf, int isize, unsigned char *obuf,
int osize)
{
struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
SKCIPHER_REQUEST_ON_STACK(req, state->arc4);
SYNC_SKCIPHER_REQUEST_ON_STACK(req, state->arc4);
unsigned ccount;
int flushed = MPPE_BITS(ibuf) & MPPE_BIT_FLUSHED;
struct scatterlist sg_in[1], sg_out[1];
@ -615,7 +616,7 @@ mppe_decompress(void *arg, unsigned char *ibuf, int isize, unsigned char *obuf,
setup_sg(sg_in, ibuf, 1);
setup_sg(sg_out, obuf, 1);
skcipher_request_set_tfm(req, state->arc4);
skcipher_request_set_sync_tfm(req, state->arc4);
skcipher_request_set_callback(req, 0, NULL, NULL);
skcipher_request_set_crypt(req, sg_in, sg_out, 1, NULL);
if (crypto_skcipher_decrypt(req)) {