Commit 5fb8ef25 authored by Ard Biesheuvel's avatar Ard Biesheuvel Committed by Herbert Xu
Browse files

crypto: chacha - move existing library code into lib/crypto 



Currently, our generic ChaCha implementation consists of a permute
function in lib/chacha.c that operates on the 64-byte ChaCha state
directly [and which is always included into the core kernel since it
is used by the /dev/random driver], and the crypto API plumbing to
expose it as a skcipher.

In order to support in-kernel users that need the ChaCha streamcipher
but have no need [or tolerance] for going through the abstractions of
the crypto API, let's expose the streamcipher bits via a library API
as well, in a way that permits the implementation to be superseded by
an architecture specific one if provided.

So move the streamcipher code into a separate module in lib/crypto,
and expose the init() and crypt() routines to users of the library.

Signed-off-by: default avatarArd Biesheuvel <ardb@kernel.org>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent 746b2e02

arch/arm/crypto/chacha-neon-glue.c

+1 −1
Original line number Diff line number Diff line
@@ -20,7 +20,7 @@ 
 */



#include <crypto/algapi.h>

#include <crypto/chacha.h>

#include <crypto/internal/chacha.h>

#include <crypto/internal/simd.h>

#include <crypto/internal/skcipher.h>

#include <linux/kernel.h>

arch/arm64/crypto/chacha-neon-glue.c

+1 −1
Original line number Diff line number Diff line
@@ -20,7 +20,7 @@ 
 */



#include <crypto/algapi.h>

#include <crypto/chacha.h>

#include <crypto/internal/chacha.h>

#include <crypto/internal/simd.h>

#include <crypto/internal/skcipher.h>

#include <linux/kernel.h>

arch/x86/crypto/chacha_glue.c

+1 −1
Original line number Diff line number Diff line
@@ -7,7 +7,7 @@ 
 */



#include <crypto/algapi.h>

#include <crypto/chacha.h>

#include <crypto/internal/chacha.h>

#include <crypto/internal/simd.h>

#include <crypto/internal/skcipher.h>

#include <linux/kernel.h>

crypto/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -1412,6 +1412,7 @@ config CRYPTO_SALSA20 


config CRYPTO_CHACHA20

	tristate "ChaCha stream cipher algorithms"

	select CRYPTO_LIB_CHACHA_GENERIC

	select CRYPTO_SKCIPHER

	help

	  The ChaCha20, XChaCha20, and XChaCha12 stream cipher algorithms.

crypto/chacha_generic.c

+5 −55
Original line number Diff line number Diff line
@@ -8,29 +8,10 @@ 


#include <asm/unaligned.h>

#include <crypto/algapi.h>

#include <crypto/chacha.h>

#include <crypto/internal/chacha.h>

#include <crypto/internal/skcipher.h>

#include <linux/module.h>



static void chacha_docrypt(u32 *state, u8 *dst, const u8 *src,

			   unsigned int bytes, int nrounds)

{

	/* aligned to potentially speed up crypto_xor() */

	u8 stream[CHACHA_BLOCK_SIZE] __aligned(sizeof(long));



	while (bytes >= CHACHA_BLOCK_SIZE) {

		chacha_block(state, stream, nrounds);

		crypto_xor_cpy(dst, src, stream, CHACHA_BLOCK_SIZE);

		bytes -= CHACHA_BLOCK_SIZE;

		dst += CHACHA_BLOCK_SIZE;

		src += CHACHA_BLOCK_SIZE;

	}

	if (bytes) {

		chacha_block(state, stream, nrounds);

		crypto_xor_cpy(dst, src, stream, bytes);

	}

}



static int chacha_stream_xor(struct skcipher_request *req,

			     const struct chacha_ctx *ctx, const u8 *iv)

{
@@ -48,8 +29,8 @@ static int chacha_stream_xor(struct skcipher_request *req, 
		if (nbytes < walk.total)

			nbytes = round_down(nbytes, CHACHA_BLOCK_SIZE);



		chacha_docrypt(state, walk.dst.virt.addr, walk.src.virt.addr,

			       nbytes, ctx->nrounds);

		chacha_crypt_generic(state, walk.dst.virt.addr,

				     walk.src.virt.addr, nbytes, ctx->nrounds);

		err = skcipher_walk_done(&walk, walk.nbytes - nbytes);

	}
@@ -58,41 +39,10 @@ static int chacha_stream_xor(struct skcipher_request *req, 


void crypto_chacha_init(u32 *state, const struct chacha_ctx *ctx, const u8 *iv)

{

	state[0]  = 0x61707865; /* "expa" */

	state[1]  = 0x3320646e; /* "nd 3" */

	state[2]  = 0x79622d32; /* "2-by" */

	state[3]  = 0x6b206574; /* "te k" */

	state[4]  = ctx->key[0];

	state[5]  = ctx->key[1];

	state[6]  = ctx->key[2];

	state[7]  = ctx->key[3];

	state[8]  = ctx->key[4];

	state[9]  = ctx->key[5];

	state[10] = ctx->key[6];

	state[11] = ctx->key[7];

	state[12] = get_unaligned_le32(iv +  0);

	state[13] = get_unaligned_le32(iv +  4);

	state[14] = get_unaligned_le32(iv +  8);

	state[15] = get_unaligned_le32(iv + 12);

	chacha_init_generic(state, ctx->key, iv);

}

EXPORT_SYMBOL_GPL(crypto_chacha_init);



static int chacha_setkey(struct crypto_skcipher *tfm, const u8 *key,

			 unsigned int keysize, int nrounds)

{

	struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm);

	int i;



	if (keysize != CHACHA_KEY_SIZE)

		return -EINVAL;



	for (i = 0; i < ARRAY_SIZE(ctx->key); i++)

		ctx->key[i] = get_unaligned_le32(key + i * sizeof(u32));



	ctx->nrounds = nrounds;

	return 0;

}



int crypto_chacha20_setkey(struct crypto_skcipher *tfm, const u8 *key,

			   unsigned int keysize)

{
@@ -126,7 +76,7 @@ int crypto_xchacha_crypt(struct skcipher_request *req) 


	/* Compute the subkey given the original key and first 128 nonce bits */

	crypto_chacha_init(state, ctx, req->iv);

	hchacha_block(state, subctx.key, ctx->nrounds);

	hchacha_block_generic(state, subctx.key, ctx->nrounds);

	subctx.nrounds = ctx->nrounds;



	/* Build the real IV */

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