diff options
author | Eric Biggers <ebiggers@google.com> | 2018-01-05 11:09:57 -0800 |
---|---|---|
committer | Herbert Xu <herbert@gondor.apana.org.au> | 2018-01-12 23:03:41 +1100 |
commit | b62b3db76f73c5a8cc132f78e7174bf57d582182 (patch) | |
tree | 3884b118e59d0d5793a14ba891af62c130163409 | |
parent | 148b974deea927f5dbb6c468af2707b488bfa2de (diff) |
crypto: salsa20-generic - cleanup and convert to skcipher API
Convert salsa20-generic from the deprecated "blkcipher" API to the
"skcipher" API, in the process fixing it up to be thread-safe (as the
crypto API expects) by maintaining each request's state separately from
the transform context.
Also remove the unnecessary cra_alignmask and tighten validation of the
key size by accepting only 16 or 32 bytes, not anything in between.
These changes bring the code close to the way chacha20-generic does
things, so hopefully it will be easier to maintain in the future.
However, the way Salsa20 interprets the IV is still slightly different;
that was not changed.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
-rw-r--r-- | crypto/salsa20_generic.c | 240 |
1 files changed, 104 insertions, 136 deletions
diff --git a/crypto/salsa20_generic.c b/crypto/salsa20_generic.c index d7da0eea5622..8c77bc78a09f 100644 --- a/crypto/salsa20_generic.c +++ b/crypto/salsa20_generic.c @@ -19,49 +19,27 @@ * */ -#include <linux/init.h> +#include <asm/unaligned.h> +#include <crypto/internal/skcipher.h> #include <linux/module.h> -#include <linux/errno.h> -#include <linux/crypto.h> -#include <linux/types.h> -#include <linux/bitops.h> -#include <crypto/algapi.h> -#include <asm/byteorder.h> -#define SALSA20_IV_SIZE 8U -#define SALSA20_MIN_KEY_SIZE 16U -#define SALSA20_MAX_KEY_SIZE 32U +#define SALSA20_IV_SIZE 8 +#define SALSA20_MIN_KEY_SIZE 16 +#define SALSA20_MAX_KEY_SIZE 32 +#define SALSA20_BLOCK_SIZE 64 -/* - * Start of code taken from D. J. Bernstein's reference implementation. - * With some modifications and optimizations made to suit our needs. - */ - -/* -salsa20-ref.c version 20051118 -D. J. Bernstein -Public domain. -*/ - -#define U32TO8_LITTLE(p, v) \ - { (p)[0] = (v >> 0) & 0xff; (p)[1] = (v >> 8) & 0xff; \ - (p)[2] = (v >> 16) & 0xff; (p)[3] = (v >> 24) & 0xff; } -#define U8TO32_LITTLE(p) \ - (((u32)((p)[0]) ) | ((u32)((p)[1]) << 8) | \ - ((u32)((p)[2]) << 16) | ((u32)((p)[3]) << 24) ) - -struct salsa20_ctx -{ - u32 input[16]; +struct salsa20_ctx { + u32 initial_state[16]; }; -static void salsa20_wordtobyte(u8 output[64], const u32 input[16]) +static void salsa20_block(u32 *state, __le32 *stream) { u32 x[16]; int i; - memcpy(x, input, sizeof(x)); - for (i = 20; i > 0; i -= 2) { + memcpy(x, state, sizeof(x)); + + for (i = 0; i < 20; i += 2) { x[ 4] ^= rol32((x[ 0] + x[12]), 7); x[ 8] ^= rol32((x[ 4] + x[ 0]), 9); x[12] ^= rol32((x[ 8] + x[ 4]), 13); @@ -95,145 +73,135 @@ static void salsa20_wordtobyte(u8 output[64], const u32 input[16]) x[14] ^= rol32((x[13] + x[12]), 13); x[15] ^= rol32((x[14] + x[13]), 18); } - for (i = 0; i < 16; ++i) - x[i] += input[i]; - for (i = 0; i < 16; ++i) - U32TO8_LITTLE(output + 4 * i,x[i]); -} -static const char sigma[16] = "expand 32-byte k"; -static const char tau[16] = "expand 16-byte k"; + for (i = 0; i < 16; i++) + stream[i] = cpu_to_le32(x[i] + state[i]); + + if (++state[8] == 0) + state[9]++; +} -static void salsa20_keysetup(struct salsa20_ctx *ctx, const u8 *k, u32 kbytes) +static void salsa20_docrypt(u32 *state, u8 *dst, const u8 *src, + unsigned int bytes) { - const char *constants; + __le32 stream[SALSA20_BLOCK_SIZE / sizeof(__le32)]; - ctx->input[1] = U8TO32_LITTLE(k + 0); - ctx->input[2] = U8TO32_LITTLE(k + 4); - ctx->input[3] = U8TO32_LITTLE(k + 8); - ctx->input[4] = U8TO32_LITTLE(k + 12); - if (kbytes == 32) { /* recommended */ - k += 16; - constants = sigma; - } else { /* kbytes == 16 */ - constants = tau; + if (dst != src) + memcpy(dst, src, bytes); + + while (bytes >= SALSA20_BLOCK_SIZE) { + salsa20_block(state, stream); + crypto_xor(dst, (const u8 *)stream, SALSA20_BLOCK_SIZE); + bytes -= SALSA20_BLOCK_SIZE; + dst += SALSA20_BLOCK_SIZE; + } + if (bytes) { + salsa20_block(state, stream); + crypto_xor(dst, (const u8 *)stream, bytes); } - ctx->input[11] = U8TO32_LITTLE(k + 0); - ctx->input[12] = U8TO32_LITTLE(k + 4); - ctx->input[13] = U8TO32_LITTLE(k + 8); - ctx->input[14] = U8TO32_LITTLE(k + 12); - ctx->input[0] = U8TO32_LITTLE(constants + 0); - ctx->input[5] = U8TO32_LITTLE(constants + 4); - ctx->input[10] = U8TO32_LITTLE(constants + 8); - ctx->input[15] = U8TO32_LITTLE(constants + 12); } -static void salsa20_ivsetup(struct salsa20_ctx *ctx, const u8 *iv) +static void salsa20_init(u32 *state, const struct salsa20_ctx *ctx, + const u8 *iv) { - ctx->input[6] = U8TO32_LITTLE(iv + 0); - ctx->input[7] = U8TO32_LITTLE(iv + 4); - ctx->input[8] = 0; - ctx->input[9] = 0; + memcpy(state, ctx->initial_state, sizeof(ctx->initial_state)); + state[6] = get_unaligned_le32(iv + 0); + state[7] = get_unaligned_le32(iv + 4); } -static void salsa20_encrypt_bytes(struct salsa20_ctx *ctx, u8 *dst, - const u8 *src, unsigned int bytes) +static int salsa20_setkey(struct crypto_skcipher *tfm, const u8 *key, + unsigned int keysize) { - u8 buf[64]; - - if (dst != src) - memcpy(dst, src, bytes); - - while (bytes) { - salsa20_wordtobyte(buf, ctx->input); - - ctx->input[8]++; - if (!ctx->input[8]) - ctx->input[9]++; + static const char sigma[16] = "expand 32-byte k"; + static const char tau[16] = "expand 16-byte k"; + struct salsa20_ctx *ctx = crypto_skcipher_ctx(tfm); + const char *constants; - if (bytes <= 64) { - crypto_xor(dst, buf, bytes); - return; - } + if (keysize != SALSA20_MIN_KEY_SIZE && + keysize != SALSA20_MAX_KEY_SIZE) + return -EINVAL; - crypto_xor(dst, buf, 64); - bytes -= 64; - dst += 64; + ctx->initial_state[1] = get_unaligned_le32(key + 0); + ctx->initial_state[2] = get_unaligned_le32(key + 4); + ctx->initial_state[3] = get_unaligned_le32(key + 8); + ctx->initial_state[4] = get_unaligned_le32(key + 12); + if (keysize == 32) { /* recommended */ + key += 16; + constants = sigma; + } else { /* keysize == 16 */ + constants = tau; } -} - -/* - * End of code taken from D. J. Bernstein's reference implementation. - */ + ctx->initial_state[11] = get_unaligned_le32(key + 0); + ctx->initial_state[12] = get_unaligned_le32(key + 4); + ctx->initial_state[13] = get_unaligned_le32(key + 8); + ctx->initial_state[14] = get_unaligned_le32(key + 12); + ctx->initial_state[0] = get_unaligned_le32(constants + 0); + ctx->initial_state[5] = get_unaligned_le32(constants + 4); + ctx->initial_state[10] = get_unaligned_le32(constants + 8); + ctx->initial_state[15] = get_unaligned_le32(constants + 12); + + /* space for the nonce; it will be overridden for each request */ + ctx->initial_state[6] = 0; + ctx->initial_state[7] = 0; + + /* initial block number */ + ctx->initial_state[8] = 0; + ctx->initial_state[9] = 0; -static int setkey(struct crypto_tfm *tfm, const u8 *key, - unsigned int keysize) -{ - struct salsa20_ctx *ctx = crypto_tfm_ctx(tfm); - salsa20_keysetup(ctx, key, keysize); return 0; } -static int encrypt(struct blkcipher_desc *desc, - struct scatterlist *dst, struct scatterlist *src, - unsigned int nbytes) +static int salsa20_crypt(struct skcipher_request *req) { - struct blkcipher_walk walk; - struct crypto_blkcipher *tfm = desc->tfm; - struct salsa20_ctx *ctx = crypto_blkcipher_ctx(tfm); + struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); + const struct salsa20_ctx *ctx = crypto_skcipher_ctx(tfm); + struct skcipher_walk walk; + u32 state[16]; int err; - blkcipher_walk_init(&walk, dst, src, nbytes); - err = blkcipher_walk_virt_block(desc, &walk, 64); + err = skcipher_walk_virt(&walk, req, true); - salsa20_ivsetup(ctx, walk.iv); + salsa20_init(state, ctx, walk.iv); - while (walk.nbytes >= 64) { - salsa20_encrypt_bytes(ctx, walk.dst.virt.addr, - walk.src.virt.addr, - walk.nbytes - (walk.nbytes % 64)); - err = blkcipher_walk_done(desc, &walk, walk.nbytes % 64); - } + while (walk.nbytes > 0) { + unsigned int nbytes = walk.nbytes; - if (walk.nbytes) { - salsa20_encrypt_bytes(ctx, walk.dst.virt.addr, - walk.src.virt.addr, walk.nbytes); - err = blkcipher_walk_done(desc, &walk, 0); + if (nbytes < walk.total) + nbytes = round_down(nbytes, walk.stride); + + salsa20_docrypt(state, walk.dst.virt.addr, walk.src.virt.addr, + nbytes); + err = skcipher_walk_done(&walk, walk.nbytes - nbytes); } return err; } -static struct crypto_alg alg = { - .cra_name = "salsa20", - .cra_driver_name = "salsa20-generic", - .cra_priority = 100, - .cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER, - .cra_type = &crypto_blkcipher_type, - .cra_blocksize = 1, - .cra_ctxsize = sizeof(struct salsa20_ctx), - .cra_alignmask = 3, - .cra_module = THIS_MODULE, - .cra_u = { - .blkcipher = { - .setkey = setkey, - .encrypt = encrypt, - .decrypt = encrypt, - .min_keysize = SALSA20_MIN_KEY_SIZE, - .max_keysize = SALSA20_MAX_KEY_SIZE, - .ivsize = SALSA20_IV_SIZE, - } - } +static struct skcipher_alg alg = { + .base.cra_name = "salsa20", + .base.cra_driver_name = "salsa20-generic", + .base.cra_priority = 100, + .base.cra_blocksize = 1, + .base.cra_ctxsize = sizeof(struct salsa20_ctx), + .base.cra_module = THIS_MODULE, + + .min_keysize = SALSA20_MIN_KEY_SIZE, + .max_keysize = SALSA20_MAX_KEY_SIZE, + .ivsize = SALSA20_IV_SIZE, + .chunksize = SALSA20_BLOCK_SIZE, + .setkey = salsa20_setkey, + .encrypt = salsa20_crypt, + .decrypt = salsa20_crypt, }; static int __init salsa20_generic_mod_init(void) { - return crypto_register_alg(&alg); + return crypto_register_skcipher(&alg); } static void __exit salsa20_generic_mod_fini(void) { - crypto_unregister_alg(&alg); + crypto_unregister_skcipher(&alg); } module_init(salsa20_generic_mod_init); |