ppp: mppe: Remove VLA usage of skcipher

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>

diff --git a/drivers/net/ppp/ppp_mppe.c b/drivers/net/ppp/ppp_mppe.c
index a205750b431ba5565df39a3d7d94ac409513fd9e..7ccdc62c6052e0ab49f7b7c9a7ba2c7bbb3be490 100644 (file)
--- 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 @@ 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)) {