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![Eric Biggers](/assets/img/avatar_default.png)
commitedaf28e996
upstream. If the user-provided IV needs to be aligned to the algorithm's alignmask, then skcipher_walk_virt() copies the IV into a new aligned buffer walk.iv. But skcipher_walk_virt() can fail afterwards, and then if the caller unconditionally accesses walk.iv, it's a use-after-free. salsa20-generic doesn't set an alignmask, so currently it isn't affected by this despite unconditionally accessing walk.iv. However this is more subtle than desired, and it was actually broken prior to the alignmask being removed by commitb62b3db76f
("crypto: salsa20-generic - cleanup and convert to skcipher API"). Since salsa20-generic does not update the IV and does not need any IV alignment, update it to use req->iv instead of walk.iv. Fixes:2407d60872
("[CRYPTO] salsa20: Salsa20 stream cipher") Cc: stable@vger.kernel.org Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
245 lines
6.5 KiB
C
245 lines
6.5 KiB
C
/*
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* Salsa20: Salsa20 stream cipher algorithm
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*
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* Copyright (c) 2007 Tan Swee Heng <thesweeheng@gmail.com>
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*
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* Derived from:
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* - salsa20.c: Public domain C code by Daniel J. Bernstein <djb@cr.yp.to>
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*
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* Salsa20 is a stream cipher candidate in eSTREAM, the ECRYPT Stream
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* Cipher Project. It is designed by Daniel J. Bernstein <djb@cr.yp.to>.
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* More information about eSTREAM and Salsa20 can be found here:
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* http://www.ecrypt.eu.org/stream/
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* http://cr.yp.to/snuffle.html
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the Free
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* Software Foundation; either version 2 of the License, or (at your option)
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* any later version.
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*
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*/
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/errno.h>
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#include <linux/crypto.h>
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#include <linux/types.h>
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#include <linux/bitops.h>
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#include <crypto/algapi.h>
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#include <asm/byteorder.h>
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#define SALSA20_IV_SIZE 8U
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#define SALSA20_MIN_KEY_SIZE 16U
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#define SALSA20_MAX_KEY_SIZE 32U
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/*
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* Start of code taken from D. J. Bernstein's reference implementation.
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* With some modifications and optimizations made to suit our needs.
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*/
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/*
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salsa20-ref.c version 20051118
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D. J. Bernstein
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Public domain.
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*/
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#define U32TO8_LITTLE(p, v) \
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{ (p)[0] = (v >> 0) & 0xff; (p)[1] = (v >> 8) & 0xff; \
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(p)[2] = (v >> 16) & 0xff; (p)[3] = (v >> 24) & 0xff; }
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#define U8TO32_LITTLE(p) \
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(((u32)((p)[0]) ) | ((u32)((p)[1]) << 8) | \
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((u32)((p)[2]) << 16) | ((u32)((p)[3]) << 24) )
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struct salsa20_ctx
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{
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u32 input[16];
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};
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static void salsa20_wordtobyte(u8 output[64], const u32 input[16])
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{
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u32 x[16];
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int i;
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memcpy(x, input, sizeof(x));
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for (i = 20; i > 0; i -= 2) {
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x[ 4] ^= rol32((x[ 0] + x[12]), 7);
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x[ 8] ^= rol32((x[ 4] + x[ 0]), 9);
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x[12] ^= rol32((x[ 8] + x[ 4]), 13);
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x[ 0] ^= rol32((x[12] + x[ 8]), 18);
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x[ 9] ^= rol32((x[ 5] + x[ 1]), 7);
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x[13] ^= rol32((x[ 9] + x[ 5]), 9);
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x[ 1] ^= rol32((x[13] + x[ 9]), 13);
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x[ 5] ^= rol32((x[ 1] + x[13]), 18);
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x[14] ^= rol32((x[10] + x[ 6]), 7);
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x[ 2] ^= rol32((x[14] + x[10]), 9);
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x[ 6] ^= rol32((x[ 2] + x[14]), 13);
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x[10] ^= rol32((x[ 6] + x[ 2]), 18);
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x[ 3] ^= rol32((x[15] + x[11]), 7);
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x[ 7] ^= rol32((x[ 3] + x[15]), 9);
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x[11] ^= rol32((x[ 7] + x[ 3]), 13);
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x[15] ^= rol32((x[11] + x[ 7]), 18);
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x[ 1] ^= rol32((x[ 0] + x[ 3]), 7);
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x[ 2] ^= rol32((x[ 1] + x[ 0]), 9);
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x[ 3] ^= rol32((x[ 2] + x[ 1]), 13);
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x[ 0] ^= rol32((x[ 3] + x[ 2]), 18);
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x[ 6] ^= rol32((x[ 5] + x[ 4]), 7);
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x[ 7] ^= rol32((x[ 6] + x[ 5]), 9);
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x[ 4] ^= rol32((x[ 7] + x[ 6]), 13);
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x[ 5] ^= rol32((x[ 4] + x[ 7]), 18);
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x[11] ^= rol32((x[10] + x[ 9]), 7);
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x[ 8] ^= rol32((x[11] + x[10]), 9);
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x[ 9] ^= rol32((x[ 8] + x[11]), 13);
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x[10] ^= rol32((x[ 9] + x[ 8]), 18);
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x[12] ^= rol32((x[15] + x[14]), 7);
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x[13] ^= rol32((x[12] + x[15]), 9);
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x[14] ^= rol32((x[13] + x[12]), 13);
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x[15] ^= rol32((x[14] + x[13]), 18);
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}
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for (i = 0; i < 16; ++i)
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x[i] += input[i];
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for (i = 0; i < 16; ++i)
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U32TO8_LITTLE(output + 4 * i,x[i]);
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}
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static const char sigma[16] = "expand 32-byte k";
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static const char tau[16] = "expand 16-byte k";
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static void salsa20_keysetup(struct salsa20_ctx *ctx, const u8 *k, u32 kbytes)
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{
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const char *constants;
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ctx->input[1] = U8TO32_LITTLE(k + 0);
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ctx->input[2] = U8TO32_LITTLE(k + 4);
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ctx->input[3] = U8TO32_LITTLE(k + 8);
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ctx->input[4] = U8TO32_LITTLE(k + 12);
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if (kbytes == 32) { /* recommended */
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k += 16;
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constants = sigma;
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} else { /* kbytes == 16 */
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constants = tau;
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}
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ctx->input[11] = U8TO32_LITTLE(k + 0);
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ctx->input[12] = U8TO32_LITTLE(k + 4);
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ctx->input[13] = U8TO32_LITTLE(k + 8);
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ctx->input[14] = U8TO32_LITTLE(k + 12);
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ctx->input[0] = U8TO32_LITTLE(constants + 0);
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ctx->input[5] = U8TO32_LITTLE(constants + 4);
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ctx->input[10] = U8TO32_LITTLE(constants + 8);
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ctx->input[15] = U8TO32_LITTLE(constants + 12);
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}
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static void salsa20_ivsetup(struct salsa20_ctx *ctx, const u8 *iv)
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{
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ctx->input[6] = U8TO32_LITTLE(iv + 0);
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ctx->input[7] = U8TO32_LITTLE(iv + 4);
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ctx->input[8] = 0;
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ctx->input[9] = 0;
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}
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static void salsa20_encrypt_bytes(struct salsa20_ctx *ctx, u8 *dst,
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const u8 *src, unsigned int bytes)
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{
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u8 buf[64];
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if (dst != src)
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memcpy(dst, src, bytes);
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while (bytes) {
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salsa20_wordtobyte(buf, ctx->input);
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ctx->input[8]++;
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if (!ctx->input[8])
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ctx->input[9]++;
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if (bytes <= 64) {
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crypto_xor(dst, buf, bytes);
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return;
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}
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crypto_xor(dst, buf, 64);
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bytes -= 64;
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dst += 64;
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}
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}
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/*
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* End of code taken from D. J. Bernstein's reference implementation.
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*/
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static int setkey(struct crypto_tfm *tfm, const u8 *key,
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unsigned int keysize)
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{
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struct salsa20_ctx *ctx = crypto_tfm_ctx(tfm);
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salsa20_keysetup(ctx, key, keysize);
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return 0;
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}
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static int encrypt(struct blkcipher_desc *desc,
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struct scatterlist *dst, struct scatterlist *src,
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unsigned int nbytes)
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{
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struct blkcipher_walk walk;
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struct crypto_blkcipher *tfm = desc->tfm;
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struct salsa20_ctx *ctx = crypto_blkcipher_ctx(tfm);
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int err;
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blkcipher_walk_init(&walk, dst, src, nbytes);
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err = blkcipher_walk_virt_block(desc, &walk, 64);
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salsa20_ivsetup(ctx, desc->info);
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while (walk.nbytes >= 64) {
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salsa20_encrypt_bytes(ctx, walk.dst.virt.addr,
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walk.src.virt.addr,
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walk.nbytes - (walk.nbytes % 64));
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err = blkcipher_walk_done(desc, &walk, walk.nbytes % 64);
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}
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if (walk.nbytes) {
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salsa20_encrypt_bytes(ctx, walk.dst.virt.addr,
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walk.src.virt.addr, walk.nbytes);
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err = blkcipher_walk_done(desc, &walk, 0);
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}
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return err;
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}
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static struct crypto_alg alg = {
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.cra_name = "salsa20",
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.cra_driver_name = "salsa20-generic",
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.cra_priority = 100,
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.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER,
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.cra_type = &crypto_blkcipher_type,
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.cra_blocksize = 1,
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.cra_ctxsize = sizeof(struct salsa20_ctx),
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.cra_alignmask = 3,
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.cra_module = THIS_MODULE,
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.cra_u = {
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.blkcipher = {
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.setkey = setkey,
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.encrypt = encrypt,
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.decrypt = encrypt,
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.min_keysize = SALSA20_MIN_KEY_SIZE,
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.max_keysize = SALSA20_MAX_KEY_SIZE,
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.ivsize = SALSA20_IV_SIZE,
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}
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}
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};
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static int __init salsa20_generic_mod_init(void)
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{
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return crypto_register_alg(&alg);
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}
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static void __exit salsa20_generic_mod_fini(void)
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{
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crypto_unregister_alg(&alg);
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}
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module_init(salsa20_generic_mod_init);
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module_exit(salsa20_generic_mod_fini);
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MODULE_LICENSE("GPL");
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MODULE_DESCRIPTION ("Salsa20 stream cipher algorithm");
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MODULE_ALIAS_CRYPTO("salsa20");
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MODULE_ALIAS_CRYPTO("salsa20-generic");
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