Commit 0e5a610b authored by Ard Biesheuvel's avatar Ard Biesheuvel Committed by Herbert Xu
Browse files

ppp: mppe: switch to RC4 library interface 



The MPPE code uses the sync skcipher to invoke the ecb(arc4) skcipher,
of which only a single generic C code implementation exists. This means
that going through all the trouble of using scatterlists etc buys us
very little, and we're better off just invoking the arc4 library directly.

Note that the SHA1 shash used by this driver has several accelerated
implementations for various architectures, so retaining that part does
make sense.

Cc: linux-ppp@vger.kernel.org
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent 611a23c2

drivers/net/ppp/Kconfig

+1 −2
Original line number Diff line number Diff line
@@ -86,8 +86,7 @@ config PPP_MPPE 
	depends on PPP

	select CRYPTO

	select CRYPTO_SHA1

	select CRYPTO_ARC4

	select CRYPTO_ECB

	select CRYPTO_LIB_ARC4

	---help---

	  Support for the MPPE Encryption protocol, as employed by the

	  Microsoft Point-to-Point Tunneling Protocol.

drivers/net/ppp/ppp_mppe.c

+14 −83
Original line number Diff line number Diff line
@@ -42,9 +42,10 @@ 
 *                    deprecated in 2.6

 */



#include <crypto/arc4.h>

#include <crypto/hash.h>

#include <crypto/skcipher.h>

#include <linux/err.h>

#include <linux/fips.h>

#include <linux/module.h>

#include <linux/kernel.h>

#include <linux/init.h>
@@ -65,13 +66,6 @@ MODULE_LICENSE("Dual BSD/GPL"); 
MODULE_ALIAS("ppp-compress-" __stringify(CI_MPPE));

MODULE_VERSION("1.0.2");



static unsigned int

setup_sg(struct scatterlist *sg, const void *address, unsigned int length)

{

	sg_set_buf(sg, address, length);

	return length;

}



#define SHA1_PAD_SIZE 40



/*
@@ -95,7 +89,7 @@ static inline void sha_pad_init(struct sha_pad *shapad) 
 * State for an MPPE (de)compressor.

 */

struct ppp_mppe_state {

	struct crypto_sync_skcipher *arc4;

	struct arc4_ctx arc4;

	struct shash_desc *sha1;

	unsigned char *sha1_digest;

	unsigned char master_key[MPPE_MAX_KEY_LEN];
@@ -154,24 +148,11 @@ 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];

	SYNC_SKCIPHER_REQUEST_ON_STACK(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_sync_skcipher_setkey(state->arc4, state->sha1_digest,

		arc4_setkey(&state->arc4, state->sha1_digest, state->keylen);

		arc4_crypt(&state->arc4, state->session_key, 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);

		setup_sg(sg_out, state->session_key, state->keylen);

		skcipher_request_set_crypt(req, sg_in, sg_out, state->keylen,

					   NULL);

		if (crypto_skcipher_encrypt(req))

    		    printk(KERN_WARNING "mppe_rekey: cipher_encrypt failed\n");

	} else {

		memcpy(state->session_key, state->sha1_digest, state->keylen);

	}
@@ -181,9 +162,7 @@ static void mppe_rekey(struct ppp_mppe_state * state, int initial_key) 
		state->session_key[1] = 0x26;

		state->session_key[2] = 0x9e;

	}

	crypto_sync_skcipher_setkey(state->arc4, state->session_key,

				    state->keylen);

	skcipher_request_zero(req);

	arc4_setkey(&state->arc4, state->session_key, state->keylen);

}



/*
@@ -196,7 +175,8 @@ static void *mppe_alloc(unsigned char *options, int optlen) 
	unsigned int digestsize;



	if (optlen != CILEN_MPPE + sizeof(state->master_key) ||

	    options[0] != CI_MPPE || options[1] != CILEN_MPPE)

	    options[0] != CI_MPPE || options[1] != CILEN_MPPE ||

	    fips_enabled)

		goto out;



	state = kzalloc(sizeof(*state), GFP_KERNEL);
@@ -204,12 +184,6 @@ static void *mppe_alloc(unsigned char *options, int optlen) 
		goto out;





	state->arc4 = crypto_alloc_sync_skcipher("ecb(arc4)", 0, 0);

	if (IS_ERR(state->arc4)) {

		state->arc4 = NULL;

		goto out_free;

	}



	shash = crypto_alloc_shash("sha1", 0, 0);

	if (IS_ERR(shash))

		goto out_free;
@@ -250,7 +224,6 @@ out_free: 
		crypto_free_shash(state->sha1->tfm);

		kzfree(state->sha1);

	}

	crypto_free_sync_skcipher(state->arc4);

	kfree(state);

out:

	return NULL;
@@ -266,8 +239,7 @@ static void mppe_free(void *arg) 
		kfree(state->sha1_digest);

		crypto_free_shash(state->sha1->tfm);

		kzfree(state->sha1);

		crypto_free_sync_skcipher(state->arc4);

		kfree(state);

		kzfree(state);

	}

}
@@ -366,10 +338,7 @@ mppe_compress(void *arg, unsigned char *ibuf, unsigned char *obuf, 
	      int isize, int osize)

{

	struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;

	SYNC_SKCIPHER_REQUEST_ON_STACK(req, state->arc4);

	int proto;

	int err;

	struct scatterlist sg_in[1], sg_out[1];



	/*

	 * Check that the protocol is in the range we handle.
@@ -420,21 +389,7 @@ mppe_compress(void *arg, unsigned char *ibuf, unsigned char *obuf, 
	ibuf += 2;		/* skip to proto field */

	isize -= 2;



	/* Encrypt packet */

	sg_init_table(sg_in, 1);

	sg_init_table(sg_out, 1);

	setup_sg(sg_in, ibuf, isize);

	setup_sg(sg_out, obuf, osize);



	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);

	skcipher_request_zero(req);

	if (err) {

		printk(KERN_DEBUG "crypto_cypher_encrypt failed\n");

		return -1;

	}

	arc4_crypt(&state->arc4, obuf, ibuf, isize);



	state->stats.unc_bytes += isize;

	state->stats.unc_packets++;
@@ -480,10 +435,8 @@ mppe_decompress(void *arg, unsigned char *ibuf, int isize, unsigned char *obuf, 
		int osize)

{

	struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;

	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];



	if (isize <= PPP_HDRLEN + MPPE_OVHD) {

		if (state->debug)
@@ -610,19 +563,7 @@ mppe_decompress(void *arg, unsigned char *ibuf, int isize, unsigned char *obuf, 
	 * Decrypt the first byte in order to check if it is

	 * a compressed or uncompressed protocol field.

	 */

	sg_init_table(sg_in, 1);

	sg_init_table(sg_out, 1);

	setup_sg(sg_in, ibuf, 1);

	setup_sg(sg_out, obuf, 1);



	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)) {

		printk(KERN_DEBUG "crypto_cypher_decrypt failed\n");

		osize = DECOMP_ERROR;

		goto out_zap_req;

	}

	arc4_crypt(&state->arc4, obuf, ibuf, 1);



	/*

	 * Do PFC decompression.
@@ -637,14 +578,7 @@ mppe_decompress(void *arg, unsigned char *ibuf, int isize, unsigned char *obuf, 
	}



	/* And finally, decrypt the rest of the packet. */

	setup_sg(sg_in, ibuf + 1, isize - 1);

	setup_sg(sg_out, obuf + 1, osize - 1);

	skcipher_request_set_crypt(req, sg_in, sg_out, isize - 1, NULL);

	if (crypto_skcipher_decrypt(req)) {

		printk(KERN_DEBUG "crypto_cypher_decrypt failed\n");

		osize = DECOMP_ERROR;

		goto out_zap_req;

	}

	arc4_crypt(&state->arc4, obuf + 1, ibuf + 1, isize - 1);



	state->stats.unc_bytes += osize;

	state->stats.unc_packets++;
@@ -654,8 +588,6 @@ mppe_decompress(void *arg, unsigned char *ibuf, int isize, unsigned char *obuf, 
	/* good packet credit */

	state->sanity_errors >>= 1;



out_zap_req:

	skcipher_request_zero(req);

	return osize;



sanity_error:
@@ -728,8 +660,7 @@ static struct compressor ppp_mppe = { 
static int __init ppp_mppe_init(void)

{

	int answer;

	if (!(crypto_has_skcipher("ecb(arc4)", 0, CRYPTO_ALG_ASYNC) &&

	      crypto_has_ahash("sha1", 0, CRYPTO_ALG_ASYNC)))

	if (fips_enabled || !crypto_has_ahash("sha1", 0, CRYPTO_ALG_ASYNC))

		return -ENODEV;



	sha_pad = kmalloc(sizeof(struct sha_pad), GFP_KERNEL);

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