From: Eric Biggers <ebiggers@xxxxxxxxxx>
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@xxxxxxxxxx>
---
crypto/salsa20_generic.c | 240 ++++++++++++++++++++---------------------------
1 file changed, 104 insertions(+), 136 deletions(-)
diff --git a/crypto/salsa20_generic.c b/crypto/salsa20_generic.c
index d7da0eea5622..59f64e041a7f 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, u32 *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] = (__force u32)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;
+ u32 stream[SALSA20_BLOCK_SIZE / sizeof(u32)];
- 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);
--
2.15.1
