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Subject[PATCH crypto-next 09/23] ppp: mppe: Remove VLA usage of skcipher
Date
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>
---
drivers/net/ppp/ppp_mppe.c | 27 ++++++++++++++-------------
1 file changed, 14 insertions(+), 13 deletions(-)

diff --git a/drivers/net/ppp/ppp_mppe.c b/drivers/net/ppp/ppp_mppe.c
index a205750b431b..7ccdc62c6052 100644
--- a/drivers/net/ppp/ppp_mppe.c
+++ b/drivers/net/ppp/ppp_mppe.c
@@ -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 @@ static void *mppe_alloc(unsigned char *options, int optlen)
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)) {
--
2.17.1
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