linux/crypto/poly1305_generic.c
Eric Biggers a16e772e66 crypto: poly1305 - remove ->setkey() method
Since Poly1305 requires a nonce per invocation, the Linux kernel
implementations of Poly1305 don't use the crypto API's keying mechanism
and instead expect the key and nonce as the first 32 bytes of the data.
But ->setkey() is still defined as a stub returning an error code.  This
prevents Poly1305 from being used through AF_ALG and will also break it
completely once we start enforcing that all crypto API users (not just
AF_ALG) call ->setkey() if present.

Fix it by removing crypto_poly1305_setkey(), leaving ->setkey as NULL.

Cc: stable@vger.kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2018-01-12 23:03:14 +11:00

306 lines
7.8 KiB
C

/*
* Poly1305 authenticator algorithm, RFC7539
*
* Copyright (C) 2015 Martin Willi
*
* Based on public domain code by Andrew Moon and Daniel J. Bernstein.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*/
#include <crypto/algapi.h>
#include <crypto/internal/hash.h>
#include <crypto/poly1305.h>
#include <linux/crypto.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <asm/unaligned.h>
static inline u64 mlt(u64 a, u64 b)
{
return a * b;
}
static inline u32 sr(u64 v, u_char n)
{
return v >> n;
}
static inline u32 and(u32 v, u32 mask)
{
return v & mask;
}
int crypto_poly1305_init(struct shash_desc *desc)
{
struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc);
memset(dctx->h, 0, sizeof(dctx->h));
dctx->buflen = 0;
dctx->rset = false;
dctx->sset = false;
return 0;
}
EXPORT_SYMBOL_GPL(crypto_poly1305_init);
static void poly1305_setrkey(struct poly1305_desc_ctx *dctx, const u8 *key)
{
/* r &= 0xffffffc0ffffffc0ffffffc0fffffff */
dctx->r[0] = (get_unaligned_le32(key + 0) >> 0) & 0x3ffffff;
dctx->r[1] = (get_unaligned_le32(key + 3) >> 2) & 0x3ffff03;
dctx->r[2] = (get_unaligned_le32(key + 6) >> 4) & 0x3ffc0ff;
dctx->r[3] = (get_unaligned_le32(key + 9) >> 6) & 0x3f03fff;
dctx->r[4] = (get_unaligned_le32(key + 12) >> 8) & 0x00fffff;
}
static void poly1305_setskey(struct poly1305_desc_ctx *dctx, const u8 *key)
{
dctx->s[0] = get_unaligned_le32(key + 0);
dctx->s[1] = get_unaligned_le32(key + 4);
dctx->s[2] = get_unaligned_le32(key + 8);
dctx->s[3] = get_unaligned_le32(key + 12);
}
/*
* Poly1305 requires a unique key for each tag, which implies that we can't set
* it on the tfm that gets accessed by multiple users simultaneously. Instead we
* expect the key as the first 32 bytes in the update() call.
*/
unsigned int crypto_poly1305_setdesckey(struct poly1305_desc_ctx *dctx,
const u8 *src, unsigned int srclen)
{
if (!dctx->sset) {
if (!dctx->rset && srclen >= POLY1305_BLOCK_SIZE) {
poly1305_setrkey(dctx, src);
src += POLY1305_BLOCK_SIZE;
srclen -= POLY1305_BLOCK_SIZE;
dctx->rset = true;
}
if (srclen >= POLY1305_BLOCK_SIZE) {
poly1305_setskey(dctx, src);
src += POLY1305_BLOCK_SIZE;
srclen -= POLY1305_BLOCK_SIZE;
dctx->sset = true;
}
}
return srclen;
}
EXPORT_SYMBOL_GPL(crypto_poly1305_setdesckey);
static unsigned int poly1305_blocks(struct poly1305_desc_ctx *dctx,
const u8 *src, unsigned int srclen,
u32 hibit)
{
u32 r0, r1, r2, r3, r4;
u32 s1, s2, s3, s4;
u32 h0, h1, h2, h3, h4;
u64 d0, d1, d2, d3, d4;
unsigned int datalen;
if (unlikely(!dctx->sset)) {
datalen = crypto_poly1305_setdesckey(dctx, src, srclen);
src += srclen - datalen;
srclen = datalen;
}
r0 = dctx->r[0];
r1 = dctx->r[1];
r2 = dctx->r[2];
r3 = dctx->r[3];
r4 = dctx->r[4];
s1 = r1 * 5;
s2 = r2 * 5;
s3 = r3 * 5;
s4 = r4 * 5;
h0 = dctx->h[0];
h1 = dctx->h[1];
h2 = dctx->h[2];
h3 = dctx->h[3];
h4 = dctx->h[4];
while (likely(srclen >= POLY1305_BLOCK_SIZE)) {
/* h += m[i] */
h0 += (get_unaligned_le32(src + 0) >> 0) & 0x3ffffff;
h1 += (get_unaligned_le32(src + 3) >> 2) & 0x3ffffff;
h2 += (get_unaligned_le32(src + 6) >> 4) & 0x3ffffff;
h3 += (get_unaligned_le32(src + 9) >> 6) & 0x3ffffff;
h4 += (get_unaligned_le32(src + 12) >> 8) | hibit;
/* h *= r */
d0 = mlt(h0, r0) + mlt(h1, s4) + mlt(h2, s3) +
mlt(h3, s2) + mlt(h4, s1);
d1 = mlt(h0, r1) + mlt(h1, r0) + mlt(h2, s4) +
mlt(h3, s3) + mlt(h4, s2);
d2 = mlt(h0, r2) + mlt(h1, r1) + mlt(h2, r0) +
mlt(h3, s4) + mlt(h4, s3);
d3 = mlt(h0, r3) + mlt(h1, r2) + mlt(h2, r1) +
mlt(h3, r0) + mlt(h4, s4);
d4 = mlt(h0, r4) + mlt(h1, r3) + mlt(h2, r2) +
mlt(h3, r1) + mlt(h4, r0);
/* (partial) h %= p */
d1 += sr(d0, 26); h0 = and(d0, 0x3ffffff);
d2 += sr(d1, 26); h1 = and(d1, 0x3ffffff);
d3 += sr(d2, 26); h2 = and(d2, 0x3ffffff);
d4 += sr(d3, 26); h3 = and(d3, 0x3ffffff);
h0 += sr(d4, 26) * 5; h4 = and(d4, 0x3ffffff);
h1 += h0 >> 26; h0 = h0 & 0x3ffffff;
src += POLY1305_BLOCK_SIZE;
srclen -= POLY1305_BLOCK_SIZE;
}
dctx->h[0] = h0;
dctx->h[1] = h1;
dctx->h[2] = h2;
dctx->h[3] = h3;
dctx->h[4] = h4;
return srclen;
}
int crypto_poly1305_update(struct shash_desc *desc,
const u8 *src, unsigned int srclen)
{
struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc);
unsigned int bytes;
if (unlikely(dctx->buflen)) {
bytes = min(srclen, POLY1305_BLOCK_SIZE - dctx->buflen);
memcpy(dctx->buf + dctx->buflen, src, bytes);
src += bytes;
srclen -= bytes;
dctx->buflen += bytes;
if (dctx->buflen == POLY1305_BLOCK_SIZE) {
poly1305_blocks(dctx, dctx->buf,
POLY1305_BLOCK_SIZE, 1 << 24);
dctx->buflen = 0;
}
}
if (likely(srclen >= POLY1305_BLOCK_SIZE)) {
bytes = poly1305_blocks(dctx, src, srclen, 1 << 24);
src += srclen - bytes;
srclen = bytes;
}
if (unlikely(srclen)) {
dctx->buflen = srclen;
memcpy(dctx->buf, src, srclen);
}
return 0;
}
EXPORT_SYMBOL_GPL(crypto_poly1305_update);
int crypto_poly1305_final(struct shash_desc *desc, u8 *dst)
{
struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc);
u32 h0, h1, h2, h3, h4;
u32 g0, g1, g2, g3, g4;
u32 mask;
u64 f = 0;
if (unlikely(!dctx->sset))
return -ENOKEY;
if (unlikely(dctx->buflen)) {
dctx->buf[dctx->buflen++] = 1;
memset(dctx->buf + dctx->buflen, 0,
POLY1305_BLOCK_SIZE - dctx->buflen);
poly1305_blocks(dctx, dctx->buf, POLY1305_BLOCK_SIZE, 0);
}
/* fully carry h */
h0 = dctx->h[0];
h1 = dctx->h[1];
h2 = dctx->h[2];
h3 = dctx->h[3];
h4 = dctx->h[4];
h2 += (h1 >> 26); h1 = h1 & 0x3ffffff;
h3 += (h2 >> 26); h2 = h2 & 0x3ffffff;
h4 += (h3 >> 26); h3 = h3 & 0x3ffffff;
h0 += (h4 >> 26) * 5; h4 = h4 & 0x3ffffff;
h1 += (h0 >> 26); h0 = h0 & 0x3ffffff;
/* compute h + -p */
g0 = h0 + 5;
g1 = h1 + (g0 >> 26); g0 &= 0x3ffffff;
g2 = h2 + (g1 >> 26); g1 &= 0x3ffffff;
g3 = h3 + (g2 >> 26); g2 &= 0x3ffffff;
g4 = h4 + (g3 >> 26) - (1 << 26); g3 &= 0x3ffffff;
/* select h if h < p, or h + -p if h >= p */
mask = (g4 >> ((sizeof(u32) * 8) - 1)) - 1;
g0 &= mask;
g1 &= mask;
g2 &= mask;
g3 &= mask;
g4 &= mask;
mask = ~mask;
h0 = (h0 & mask) | g0;
h1 = (h1 & mask) | g1;
h2 = (h2 & mask) | g2;
h3 = (h3 & mask) | g3;
h4 = (h4 & mask) | g4;
/* h = h % (2^128) */
h0 = (h0 >> 0) | (h1 << 26);
h1 = (h1 >> 6) | (h2 << 20);
h2 = (h2 >> 12) | (h3 << 14);
h3 = (h3 >> 18) | (h4 << 8);
/* mac = (h + s) % (2^128) */
f = (f >> 32) + h0 + dctx->s[0]; put_unaligned_le32(f, dst + 0);
f = (f >> 32) + h1 + dctx->s[1]; put_unaligned_le32(f, dst + 4);
f = (f >> 32) + h2 + dctx->s[2]; put_unaligned_le32(f, dst + 8);
f = (f >> 32) + h3 + dctx->s[3]; put_unaligned_le32(f, dst + 12);
return 0;
}
EXPORT_SYMBOL_GPL(crypto_poly1305_final);
static struct shash_alg poly1305_alg = {
.digestsize = POLY1305_DIGEST_SIZE,
.init = crypto_poly1305_init,
.update = crypto_poly1305_update,
.final = crypto_poly1305_final,
.descsize = sizeof(struct poly1305_desc_ctx),
.base = {
.cra_name = "poly1305",
.cra_driver_name = "poly1305-generic",
.cra_priority = 100,
.cra_flags = CRYPTO_ALG_TYPE_SHASH,
.cra_blocksize = POLY1305_BLOCK_SIZE,
.cra_module = THIS_MODULE,
},
};
static int __init poly1305_mod_init(void)
{
return crypto_register_shash(&poly1305_alg);
}
static void __exit poly1305_mod_exit(void)
{
crypto_unregister_shash(&poly1305_alg);
}
module_init(poly1305_mod_init);
module_exit(poly1305_mod_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Martin Willi <martin@strongswan.org>");
MODULE_DESCRIPTION("Poly1305 authenticator");
MODULE_ALIAS_CRYPTO("poly1305");
MODULE_ALIAS_CRYPTO("poly1305-generic");