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linux/crypto/sha256_generic.c
Daniel Borkmann 7185ad2672 crypto: memzero_explicit - make sure to clear out sensitive data 
Recently, in commit 13aa93c70e71 ("random: add and use memzero_explicit()
for clearing data"), we have found that GCC may optimize some memset()
cases away when it detects a stack variable is not being used anymore
and going out of scope. This can happen, for example, in cases when we
are clearing out sensitive information such as keying material or any
e.g. intermediate results from crypto computations, etc.

With the help of Coccinelle, we can figure out and fix such occurences
in the crypto subsytem as well. Julia Lawall provided the following
Coccinelle program:

  @@
  type T;
  identifier x;
  @@

  T x;
  ... when exists
      when any
  -memset
  +memzero_explicit
     (&x,
  -0,
     ...)
  ... when != x
      when strict

  @@
  type T;
  identifier x;
  @@

  T x[...];
  ... when exists
      when any
  -memset
  +memzero_explicit
     (x,
  -0,
     ...)
  ... when != x
      when strict

Therefore, make use of the drop-in replacement memzero_explicit() for
exactly such cases instead of using memset().

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Cc: Julia Lawall <julia.lawall@lip6.fr>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2014-10-17 11:44:07 -04:00

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/*
* Cryptographic API.
*
* SHA-256, as specified in
* http://csrc.nist.gov/groups/STM/cavp/documents/shs/sha256-384-512.pdf
*
* SHA-256 code by Jean-Luc Cooke <jlcooke@certainkey.com>.
*
* Copyright (c) Jean-Luc Cooke <jlcooke@certainkey.com>
* Copyright (c) Andrew McDonald <andrew@mcdonald.org.uk>
* Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
* SHA224 Support Copyright 2007 Intel Corporation <jonathan.lynch@intel.com>
*
* 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/internal/hash.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/types.h>
#include <crypto/sha.h>
#include <asm/byteorder.h>
static inline u32 Ch(u32 x, u32 y, u32 z)
{
return z ^ (x & (y ^ z));
}
static inline u32 Maj(u32 x, u32 y, u32 z)
{
return (x & y) | (z & (x | y));
}
#define e0(x) (ror32(x, 2) ^ ror32(x,13) ^ ror32(x,22))
#define e1(x) (ror32(x, 6) ^ ror32(x,11) ^ ror32(x,25))
#define s0(x) (ror32(x, 7) ^ ror32(x,18) ^ (x >> 3))
#define s1(x) (ror32(x,17) ^ ror32(x,19) ^ (x >> 10))
static inline void LOAD_OP(int I, u32 *W, const u8 *input)
{
W[I] = __be32_to_cpu( ((__be32*)(input))[I] );
}
static inline void BLEND_OP(int I, u32 *W)
{
W[I] = s1(W[I-2]) + W[I-7] + s0(W[I-15]) + W[I-16];
}
static void sha256_transform(u32 *state, const u8 *input)
{
u32 a, b, c, d, e, f, g, h, t1, t2;
u32 W[64];
int i;
/* load the input */
for (i = 0; i < 16; i++)
LOAD_OP(i, W, input);
/* now blend */
for (i = 16; i < 64; i++)
BLEND_OP(i, W);
/* load the state into our registers */
a=state[0]; b=state[1]; c=state[2]; d=state[3];
e=state[4]; f=state[5]; g=state[6]; h=state[7];
/* now iterate */
t1 = h + e1(e) + Ch(e,f,g) + 0x428a2f98 + W[ 0];
t2 = e0(a) + Maj(a,b,c); d+=t1; h=t1+t2;
t1 = g + e1(d) + Ch(d,e,f) + 0x71374491 + W[ 1];
t2 = e0(h) + Maj(h,a,b); c+=t1; g=t1+t2;
t1 = f + e1(c) + Ch(c,d,e) + 0xb5c0fbcf + W[ 2];
t2 = e0(g) + Maj(g,h,a); b+=t1; f=t1+t2;
t1 = e + e1(b) + Ch(b,c,d) + 0xe9b5dba5 + W[ 3];
t2 = e0(f) + Maj(f,g,h); a+=t1; e=t1+t2;
t1 = d + e1(a) + Ch(a,b,c) + 0x3956c25b + W[ 4];
t2 = e0(e) + Maj(e,f,g); h+=t1; d=t1+t2;
t1 = c + e1(h) + Ch(h,a,b) + 0x59f111f1 + W[ 5];
t2 = e0(d) + Maj(d,e,f); g+=t1; c=t1+t2;
t1 = b + e1(g) + Ch(g,h,a) + 0x923f82a4 + W[ 6];
t2 = e0(c) + Maj(c,d,e); f+=t1; b=t1+t2;
t1 = a + e1(f) + Ch(f,g,h) + 0xab1c5ed5 + W[ 7];
t2 = e0(b) + Maj(b,c,d); e+=t1; a=t1+t2;
t1 = h + e1(e) + Ch(e,f,g) + 0xd807aa98 + W[ 8];
t2 = e0(a) + Maj(a,b,c); d+=t1; h=t1+t2;
t1 = g + e1(d) + Ch(d,e,f) + 0x12835b01 + W[ 9];
t2 = e0(h) + Maj(h,a,b); c+=t1; g=t1+t2;
t1 = f + e1(c) + Ch(c,d,e) + 0x243185be + W[10];
t2 = e0(g) + Maj(g,h,a); b+=t1; f=t1+t2;
t1 = e + e1(b) + Ch(b,c,d) + 0x550c7dc3 + W[11];
t2 = e0(f) + Maj(f,g,h); a+=t1; e=t1+t2;
t1 = d + e1(a) + Ch(a,b,c) + 0x72be5d74 + W[12];
t2 = e0(e) + Maj(e,f,g); h+=t1; d=t1+t2;
t1 = c + e1(h) + Ch(h,a,b) + 0x80deb1fe + W[13];
t2 = e0(d) + Maj(d,e,f); g+=t1; c=t1+t2;
t1 = b + e1(g) + Ch(g,h,a) + 0x9bdc06a7 + W[14];
t2 = e0(c) + Maj(c,d,e); f+=t1; b=t1+t2;
t1 = a + e1(f) + Ch(f,g,h) + 0xc19bf174 + W[15];
t2 = e0(b) + Maj(b,c,d); e+=t1; a=t1+t2;
t1 = h + e1(e) + Ch(e,f,g) + 0xe49b69c1 + W[16];
t2 = e0(a) + Maj(a,b,c); d+=t1; h=t1+t2;
t1 = g + e1(d) + Ch(d,e,f) + 0xefbe4786 + W[17];
t2 = e0(h) + Maj(h,a,b); c+=t1; g=t1+t2;
t1 = f + e1(c) + Ch(c,d,e) + 0x0fc19dc6 + W[18];
t2 = e0(g) + Maj(g,h,a); b+=t1; f=t1+t2;
t1 = e + e1(b) + Ch(b,c,d) + 0x240ca1cc + W[19];
t2 = e0(f) + Maj(f,g,h); a+=t1; e=t1+t2;
t1 = d + e1(a) + Ch(a,b,c) + 0x2de92c6f + W[20];
t2 = e0(e) + Maj(e,f,g); h+=t1; d=t1+t2;
t1 = c + e1(h) + Ch(h,a,b) + 0x4a7484aa + W[21];
t2 = e0(d) + Maj(d,e,f); g+=t1; c=t1+t2;
t1 = b + e1(g) + Ch(g,h,a) + 0x5cb0a9dc + W[22];
t2 = e0(c) + Maj(c,d,e); f+=t1; b=t1+t2;
t1 = a + e1(f) + Ch(f,g,h) + 0x76f988da + W[23];
t2 = e0(b) + Maj(b,c,d); e+=t1; a=t1+t2;
t1 = h + e1(e) + Ch(e,f,g) + 0x983e5152 + W[24];
t2 = e0(a) + Maj(a,b,c); d+=t1; h=t1+t2;
t1 = g + e1(d) + Ch(d,e,f) + 0xa831c66d + W[25];
t2 = e0(h) + Maj(h,a,b); c+=t1; g=t1+t2;
t1 = f + e1(c) + Ch(c,d,e) + 0xb00327c8 + W[26];
t2 = e0(g) + Maj(g,h,a); b+=t1; f=t1+t2;
t1 = e + e1(b) + Ch(b,c,d) + 0xbf597fc7 + W[27];
t2 = e0(f) + Maj(f,g,h); a+=t1; e=t1+t2;
t1 = d + e1(a) + Ch(a,b,c) + 0xc6e00bf3 + W[28];
t2 = e0(e) + Maj(e,f,g); h+=t1; d=t1+t2;
t1 = c + e1(h) + Ch(h,a,b) + 0xd5a79147 + W[29];
t2 = e0(d) + Maj(d,e,f); g+=t1; c=t1+t2;
t1 = b + e1(g) + Ch(g,h,a) + 0x06ca6351 + W[30];
t2 = e0(c) + Maj(c,d,e); f+=t1; b=t1+t2;
t1 = a + e1(f) + Ch(f,g,h) + 0x14292967 + W[31];
t2 = e0(b) + Maj(b,c,d); e+=t1; a=t1+t2;
t1 = h + e1(e) + Ch(e,f,g) + 0x27b70a85 + W[32];
t2 = e0(a) + Maj(a,b,c); d+=t1; h=t1+t2;
t1 = g + e1(d) + Ch(d,e,f) + 0x2e1b2138 + W[33];
t2 = e0(h) + Maj(h,a,b); c+=t1; g=t1+t2;
t1 = f + e1(c) + Ch(c,d,e) + 0x4d2c6dfc + W[34];
t2 = e0(g) + Maj(g,h,a); b+=t1; f=t1+t2;
t1 = e + e1(b) + Ch(b,c,d) + 0x53380d13 + W[35];
t2 = e0(f) + Maj(f,g,h); a+=t1; e=t1+t2;
t1 = d + e1(a) + Ch(a,b,c) + 0x650a7354 + W[36];
t2 = e0(e) + Maj(e,f,g); h+=t1; d=t1+t2;
t1 = c + e1(h) + Ch(h,a,b) + 0x766a0abb + W[37];
t2 = e0(d) + Maj(d,e,f); g+=t1; c=t1+t2;
t1 = b + e1(g) + Ch(g,h,a) + 0x81c2c92e + W[38];
t2 = e0(c) + Maj(c,d,e); f+=t1; b=t1+t2;
t1 = a + e1(f) + Ch(f,g,h) + 0x92722c85 + W[39];
t2 = e0(b) + Maj(b,c,d); e+=t1; a=t1+t2;
t1 = h + e1(e) + Ch(e,f,g) + 0xa2bfe8a1 + W[40];
t2 = e0(a) + Maj(a,b,c); d+=t1; h=t1+t2;
t1 = g + e1(d) + Ch(d,e,f) + 0xa81a664b + W[41];
t2 = e0(h) + Maj(h,a,b); c+=t1; g=t1+t2;
t1 = f + e1(c) + Ch(c,d,e) + 0xc24b8b70 + W[42];
t2 = e0(g) + Maj(g,h,a); b+=t1; f=t1+t2;
t1 = e + e1(b) + Ch(b,c,d) + 0xc76c51a3 + W[43];
t2 = e0(f) + Maj(f,g,h); a+=t1; e=t1+t2;
t1 = d + e1(a) + Ch(a,b,c) + 0xd192e819 + W[44];
t2 = e0(e) + Maj(e,f,g); h+=t1; d=t1+t2;
t1 = c + e1(h) + Ch(h,a,b) + 0xd6990624 + W[45];
t2 = e0(d) + Maj(d,e,f); g+=t1; c=t1+t2;
t1 = b + e1(g) + Ch(g,h,a) + 0xf40e3585 + W[46];
t2 = e0(c) + Maj(c,d,e); f+=t1; b=t1+t2;
t1 = a + e1(f) + Ch(f,g,h) + 0x106aa070 + W[47];
t2 = e0(b) + Maj(b,c,d); e+=t1; a=t1+t2;
t1 = h + e1(e) + Ch(e,f,g) + 0x19a4c116 + W[48];
t2 = e0(a) + Maj(a,b,c); d+=t1; h=t1+t2;
t1 = g + e1(d) + Ch(d,e,f) + 0x1e376c08 + W[49];
t2 = e0(h) + Maj(h,a,b); c+=t1; g=t1+t2;
t1 = f + e1(c) + Ch(c,d,e) + 0x2748774c + W[50];
t2 = e0(g) + Maj(g,h,a); b+=t1; f=t1+t2;
t1 = e + e1(b) + Ch(b,c,d) + 0x34b0bcb5 + W[51];
t2 = e0(f) + Maj(f,g,h); a+=t1; e=t1+t2;
t1 = d + e1(a) + Ch(a,b,c) + 0x391c0cb3 + W[52];
t2 = e0(e) + Maj(e,f,g); h+=t1; d=t1+t2;
t1 = c + e1(h) + Ch(h,a,b) + 0x4ed8aa4a + W[53];
t2 = e0(d) + Maj(d,e,f); g+=t1; c=t1+t2;
t1 = b + e1(g) + Ch(g,h,a) + 0x5b9cca4f + W[54];
t2 = e0(c) + Maj(c,d,e); f+=t1; b=t1+t2;
t1 = a + e1(f) + Ch(f,g,h) + 0x682e6ff3 + W[55];
t2 = e0(b) + Maj(b,c,d); e+=t1; a=t1+t2;
t1 = h + e1(e) + Ch(e,f,g) + 0x748f82ee + W[56];
t2 = e0(a) + Maj(a,b,c); d+=t1; h=t1+t2;
t1 = g + e1(d) + Ch(d,e,f) + 0x78a5636f + W[57];
t2 = e0(h) + Maj(h,a,b); c+=t1; g=t1+t2;
t1 = f + e1(c) + Ch(c,d,e) + 0x84c87814 + W[58];
t2 = e0(g) + Maj(g,h,a); b+=t1; f=t1+t2;
t1 = e + e1(b) + Ch(b,c,d) + 0x8cc70208 + W[59];
t2 = e0(f) + Maj(f,g,h); a+=t1; e=t1+t2;
t1 = d + e1(a) + Ch(a,b,c) + 0x90befffa + W[60];
t2 = e0(e) + Maj(e,f,g); h+=t1; d=t1+t2;
t1 = c + e1(h) + Ch(h,a,b) + 0xa4506ceb + W[61];
t2 = e0(d) + Maj(d,e,f); g+=t1; c=t1+t2;
t1 = b + e1(g) + Ch(g,h,a) + 0xbef9a3f7 + W[62];
t2 = e0(c) + Maj(c,d,e); f+=t1; b=t1+t2;
t1 = a + e1(f) + Ch(f,g,h) + 0xc67178f2 + W[63];
t2 = e0(b) + Maj(b,c,d); e+=t1; a=t1+t2;
state[0] += a; state[1] += b; state[2] += c; state[3] += d;
state[4] += e; state[5] += f; state[6] += g; state[7] += h;
/* clear any sensitive info... */
a = b = c = d = e = f = g = h = t1 = t2 = 0;
memzero_explicit(W, 64 * sizeof(u32));
}
static int sha224_init(struct shash_desc *desc)
{
struct sha256_state *sctx = shash_desc_ctx(desc);
sctx->state[0] = SHA224_H0;
sctx->state[1] = SHA224_H1;
sctx->state[2] = SHA224_H2;
sctx->state[3] = SHA224_H3;
sctx->state[4] = SHA224_H4;
sctx->state[5] = SHA224_H5;
sctx->state[6] = SHA224_H6;
sctx->state[7] = SHA224_H7;
sctx->count = 0;
return 0;
}
static int sha256_init(struct shash_desc *desc)
{
struct sha256_state *sctx = shash_desc_ctx(desc);
sctx->state[0] = SHA256_H0;
sctx->state[1] = SHA256_H1;
sctx->state[2] = SHA256_H2;
sctx->state[3] = SHA256_H3;
sctx->state[4] = SHA256_H4;
sctx->state[5] = SHA256_H5;
sctx->state[6] = SHA256_H6;
sctx->state[7] = SHA256_H7;
sctx->count = 0;
return 0;
}
int crypto_sha256_update(struct shash_desc *desc, const u8 *data,
unsigned int len)
{
struct sha256_state *sctx = shash_desc_ctx(desc);
unsigned int partial, done;
const u8 *src;
partial = sctx->count & 0x3f;
sctx->count += len;
done = 0;
src = data;
if ((partial + len) > 63) {
if (partial) {
done = -partial;
memcpy(sctx->buf + partial, data, done + 64);
src = sctx->buf;
}
do {
sha256_transform(sctx->state, src);
done += 64;
src = data + done;
} while (done + 63 < len);
partial = 0;
}
memcpy(sctx->buf + partial, src, len - done);
return 0;
}
EXPORT_SYMBOL(crypto_sha256_update);
static int sha256_final(struct shash_desc *desc, u8 *out)
{
struct sha256_state *sctx = shash_desc_ctx(desc);
__be32 *dst = (__be32 *)out;
__be64 bits;
unsigned int index, pad_len;
int i;
static const u8 padding[64] = { 0x80, };
/* Save number of bits */
bits = cpu_to_be64(sctx->count << 3);
/* Pad out to 56 mod 64. */
index = sctx->count & 0x3f;
pad_len = (index < 56) ? (56 - index) : ((64+56) - index);
crypto_sha256_update(desc, padding, pad_len);
/* Append length (before padding) */
crypto_sha256_update(desc, (const u8 *)&bits, sizeof(bits));
/* Store state in digest */
for (i = 0; i < 8; i++)
dst[i] = cpu_to_be32(sctx->state[i]);
/* Zeroize sensitive information. */
memset(sctx, 0, sizeof(*sctx));
return 0;
}
static int sha224_final(struct shash_desc *desc, u8 *hash)
{
u8 D[SHA256_DIGEST_SIZE];
sha256_final(desc, D);
memcpy(hash, D, SHA224_DIGEST_SIZE);
memzero_explicit(D, SHA256_DIGEST_SIZE);
return 0;
}
static int sha256_export(struct shash_desc *desc, void *out)
{
struct sha256_state *sctx = shash_desc_ctx(desc);
memcpy(out, sctx, sizeof(*sctx));
return 0;
}
static int sha256_import(struct shash_desc *desc, const void *in)
{
struct sha256_state *sctx = shash_desc_ctx(desc);
memcpy(sctx, in, sizeof(*sctx));
return 0;
}
static struct shash_alg sha256_algs[2] = { {
.digestsize = SHA256_DIGEST_SIZE,
.init = sha256_init,
.update = crypto_sha256_update,
.final = sha256_final,
.export = sha256_export,
.import = sha256_import,
.descsize = sizeof(struct sha256_state),
.statesize = sizeof(struct sha256_state),
.base = {
.cra_name = "sha256",
.cra_driver_name= "sha256-generic",
.cra_flags = CRYPTO_ALG_TYPE_SHASH,
.cra_blocksize = SHA256_BLOCK_SIZE,
.cra_module = THIS_MODULE,
}
}, {
.digestsize = SHA224_DIGEST_SIZE,
.init = sha224_init,
.update = crypto_sha256_update,
.final = sha224_final,
.descsize = sizeof(struct sha256_state),
.base = {
.cra_name = "sha224",
.cra_driver_name= "sha224-generic",
.cra_flags = CRYPTO_ALG_TYPE_SHASH,
.cra_blocksize = SHA224_BLOCK_SIZE,
.cra_module = THIS_MODULE,
}
} };
static int __init sha256_generic_mod_init(void)
{
return crypto_register_shashes(sha256_algs, ARRAY_SIZE(sha256_algs));
}
static void __exit sha256_generic_mod_fini(void)
{
crypto_unregister_shashes(sha256_algs, ARRAY_SIZE(sha256_algs));
}
module_init(sha256_generic_mod_init);
module_exit(sha256_generic_mod_fini);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("SHA-224 and SHA-256 Secure Hash Algorithm");
MODULE_ALIAS("sha224");
MODULE_ALIAS("sha256");
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