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linux/crypto/sm4_generic.c
Eric Biggers 674f368a95 crypto: remove CRYPTO_TFM_RES_BAD_KEY_LEN 
The CRYPTO_TFM_RES_BAD_KEY_LEN flag was apparently meant as a way to
make the ->setkey() functions provide more information about errors.

However, no one actually checks for this flag, which makes it pointless.

Also, many algorithms fail to set this flag when given a bad length key.
Reviewing just the generic implementations, this is the case for
aes-fixed-time, cbcmac, echainiv, nhpoly1305, pcrypt, rfc3686, rfc4309,
rfc7539, rfc7539esp, salsa20, seqiv, and xcbc.  But there are probably
many more in arch/*/crypto/ and drivers/crypto/.

Some algorithms can even set this flag when the key is the correct
length.  For example, authenc and authencesn set it when the key payload
is malformed in any way (not just a bad length), the atmel-sha and ccree
drivers can set it if a memory allocation fails, and the chelsio driver
sets it for bad auth tag lengths, not just bad key lengths.

So even if someone actually wanted to start checking this flag (which
seems unlikely, since it's been unused for a long time), there would be
a lot of work needed to get it working correctly.  But it would probably
be much better to go back to the drawing board and just define different
return values, like -EINVAL if the key is invalid for the algorithm vs.
-EKEYREJECTED if the key was rejected by a policy like "no weak keys".
That would be much simpler, less error-prone, and easier to test.

So just remove this flag.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Horia Geantă <horia.geanta@nxp.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2020-01-09 11:30:53 +08:00

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// SPDX-License-Identifier: GPL-2.0
/*
* SM4 Cipher Algorithm.
*
* Copyright (C) 2018 ARM Limited or its affiliates.
* All rights reserved.
*/
#include <crypto/sm4.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/crypto.h>
#include <asm/byteorder.h>
#include <asm/unaligned.h>
static const u32 fk[4] = {
0xa3b1bac6, 0x56aa3350, 0x677d9197, 0xb27022dc
};
static const u8 sbox[256] = {
0xd6, 0x90, 0xe9, 0xfe, 0xcc, 0xe1, 0x3d, 0xb7,
0x16, 0xb6, 0x14, 0xc2, 0x28, 0xfb, 0x2c, 0x05,
0x2b, 0x67, 0x9a, 0x76, 0x2a, 0xbe, 0x04, 0xc3,
0xaa, 0x44, 0x13, 0x26, 0x49, 0x86, 0x06, 0x99,
0x9c, 0x42, 0x50, 0xf4, 0x91, 0xef, 0x98, 0x7a,
0x33, 0x54, 0x0b, 0x43, 0xed, 0xcf, 0xac, 0x62,
0xe4, 0xb3, 0x1c, 0xa9, 0xc9, 0x08, 0xe8, 0x95,
0x80, 0xdf, 0x94, 0xfa, 0x75, 0x8f, 0x3f, 0xa6,
0x47, 0x07, 0xa7, 0xfc, 0xf3, 0x73, 0x17, 0xba,
0x83, 0x59, 0x3c, 0x19, 0xe6, 0x85, 0x4f, 0xa8,
0x68, 0x6b, 0x81, 0xb2, 0x71, 0x64, 0xda, 0x8b,
0xf8, 0xeb, 0x0f, 0x4b, 0x70, 0x56, 0x9d, 0x35,
0x1e, 0x24, 0x0e, 0x5e, 0x63, 0x58, 0xd1, 0xa2,
0x25, 0x22, 0x7c, 0x3b, 0x01, 0x21, 0x78, 0x87,
0xd4, 0x00, 0x46, 0x57, 0x9f, 0xd3, 0x27, 0x52,
0x4c, 0x36, 0x02, 0xe7, 0xa0, 0xc4, 0xc8, 0x9e,
0xea, 0xbf, 0x8a, 0xd2, 0x40, 0xc7, 0x38, 0xb5,
0xa3, 0xf7, 0xf2, 0xce, 0xf9, 0x61, 0x15, 0xa1,
0xe0, 0xae, 0x5d, 0xa4, 0x9b, 0x34, 0x1a, 0x55,
0xad, 0x93, 0x32, 0x30, 0xf5, 0x8c, 0xb1, 0xe3,
0x1d, 0xf6, 0xe2, 0x2e, 0x82, 0x66, 0xca, 0x60,
0xc0, 0x29, 0x23, 0xab, 0x0d, 0x53, 0x4e, 0x6f,
0xd5, 0xdb, 0x37, 0x45, 0xde, 0xfd, 0x8e, 0x2f,
0x03, 0xff, 0x6a, 0x72, 0x6d, 0x6c, 0x5b, 0x51,
0x8d, 0x1b, 0xaf, 0x92, 0xbb, 0xdd, 0xbc, 0x7f,
0x11, 0xd9, 0x5c, 0x41, 0x1f, 0x10, 0x5a, 0xd8,
0x0a, 0xc1, 0x31, 0x88, 0xa5, 0xcd, 0x7b, 0xbd,
0x2d, 0x74, 0xd0, 0x12, 0xb8, 0xe5, 0xb4, 0xb0,
0x89, 0x69, 0x97, 0x4a, 0x0c, 0x96, 0x77, 0x7e,
0x65, 0xb9, 0xf1, 0x09, 0xc5, 0x6e, 0xc6, 0x84,
0x18, 0xf0, 0x7d, 0xec, 0x3a, 0xdc, 0x4d, 0x20,
0x79, 0xee, 0x5f, 0x3e, 0xd7, 0xcb, 0x39, 0x48
};
static const u32 ck[] = {
0x00070e15, 0x1c232a31, 0x383f464d, 0x545b6269,
0x70777e85, 0x8c939aa1, 0xa8afb6bd, 0xc4cbd2d9,
0xe0e7eef5, 0xfc030a11, 0x181f262d, 0x343b4249,
0x50575e65, 0x6c737a81, 0x888f969d, 0xa4abb2b9,
0xc0c7ced5, 0xdce3eaf1, 0xf8ff060d, 0x141b2229,
0x30373e45, 0x4c535a61, 0x686f767d, 0x848b9299,
0xa0a7aeb5, 0xbcc3cad1, 0xd8dfe6ed, 0xf4fb0209,
0x10171e25, 0x2c333a41, 0x484f565d, 0x646b7279
};
static u32 sm4_t_non_lin_sub(u32 x)
{
int i;
u8 *b = (u8 *)&x;
for (i = 0; i < 4; ++i)
b[i] = sbox[b[i]];
return x;
}
static u32 sm4_key_lin_sub(u32 x)
{
return x ^ rol32(x, 13) ^ rol32(x, 23);
}
static u32 sm4_enc_lin_sub(u32 x)
{
return x ^ rol32(x, 2) ^ rol32(x, 10) ^ rol32(x, 18) ^ rol32(x, 24);
}
static u32 sm4_key_sub(u32 x)
{
return sm4_key_lin_sub(sm4_t_non_lin_sub(x));
}
static u32 sm4_enc_sub(u32 x)
{
return sm4_enc_lin_sub(sm4_t_non_lin_sub(x));
}
static u32 sm4_round(const u32 *x, const u32 rk)
{
return x[0] ^ sm4_enc_sub(x[1] ^ x[2] ^ x[3] ^ rk);
}
/**
* crypto_sm4_expand_key - Expands the SM4 key as described in GB/T 32907-2016
* @ctx: The location where the computed key will be stored.
* @in_key: The supplied key.
* @key_len: The length of the supplied key.
*
* Returns 0 on success. The function fails only if an invalid key size (or
* pointer) is supplied.
*/
int crypto_sm4_expand_key(struct crypto_sm4_ctx *ctx, const u8 *in_key,
unsigned int key_len)
{
u32 rk[4], t;
const u32 *key = (u32 *)in_key;
int i;
if (key_len != SM4_KEY_SIZE)
return -EINVAL;
for (i = 0; i < 4; ++i)
rk[i] = get_unaligned_be32(&key[i]) ^ fk[i];
for (i = 0; i < 32; ++i) {
t = rk[0] ^ sm4_key_sub(rk[1] ^ rk[2] ^ rk[3] ^ ck[i]);
ctx->rkey_enc[i] = t;
rk[0] = rk[1];
rk[1] = rk[2];
rk[2] = rk[3];
rk[3] = t;
}
for (i = 0; i < 32; ++i)
ctx->rkey_dec[i] = ctx->rkey_enc[31 - i];
return 0;
}
EXPORT_SYMBOL_GPL(crypto_sm4_expand_key);
/**
* crypto_sm4_set_key - Set the SM4 key.
* @tfm: The %crypto_tfm that is used in the context.
* @in_key: The input key.
* @key_len: The size of the key.
*
* This function uses crypto_sm4_expand_key() to expand the key.
* &crypto_sm4_ctx _must_ be the private data embedded in @tfm which is
* retrieved with crypto_tfm_ctx().
*
* Return: 0 on success; -EINVAL on failure (only happens for bad key lengths)
*/
int crypto_sm4_set_key(struct crypto_tfm *tfm, const u8 *in_key,
unsigned int key_len)
{
struct crypto_sm4_ctx *ctx = crypto_tfm_ctx(tfm);
return crypto_sm4_expand_key(ctx, in_key, key_len);
}
EXPORT_SYMBOL_GPL(crypto_sm4_set_key);
static void sm4_do_crypt(const u32 *rk, u32 *out, const u32 *in)
{
u32 x[4], i, t;
for (i = 0; i < 4; ++i)
x[i] = get_unaligned_be32(&in[i]);
for (i = 0; i < 32; ++i) {
t = sm4_round(x, rk[i]);
x[0] = x[1];
x[1] = x[2];
x[2] = x[3];
x[3] = t;
}
for (i = 0; i < 4; ++i)
put_unaligned_be32(x[3 - i], &out[i]);
}
/* encrypt a block of text */
void crypto_sm4_encrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
{
const struct crypto_sm4_ctx *ctx = crypto_tfm_ctx(tfm);
sm4_do_crypt(ctx->rkey_enc, (u32 *)out, (u32 *)in);
}
EXPORT_SYMBOL_GPL(crypto_sm4_encrypt);
/* decrypt a block of text */
void crypto_sm4_decrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
{
const struct crypto_sm4_ctx *ctx = crypto_tfm_ctx(tfm);
sm4_do_crypt(ctx->rkey_dec, (u32 *)out, (u32 *)in);
}
EXPORT_SYMBOL_GPL(crypto_sm4_decrypt);
static struct crypto_alg sm4_alg = {
.cra_name = "sm4",
.cra_driver_name = "sm4-generic",
.cra_priority = 100,
.cra_flags = CRYPTO_ALG_TYPE_CIPHER,
.cra_blocksize = SM4_BLOCK_SIZE,
.cra_ctxsize = sizeof(struct crypto_sm4_ctx),
.cra_module = THIS_MODULE,
.cra_u = {
.cipher = {
.cia_min_keysize = SM4_KEY_SIZE,
.cia_max_keysize = SM4_KEY_SIZE,
.cia_setkey = crypto_sm4_set_key,
.cia_encrypt = crypto_sm4_encrypt,
.cia_decrypt = crypto_sm4_decrypt
}
}
};
static int __init sm4_init(void)
{
return crypto_register_alg(&sm4_alg);
}
static void __exit sm4_fini(void)
{
crypto_unregister_alg(&sm4_alg);
}
subsys_initcall(sm4_init);
module_exit(sm4_fini);
MODULE_DESCRIPTION("SM4 Cipher Algorithm");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS_CRYPTO("sm4");
MODULE_ALIAS_CRYPTO("sm4-generic");
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