linux/crypto/sm4_generic.c

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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>
/**
* sm4_setkey - 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 sm4_expandkey() to expand the key.
* &sm4_ctx _must_ be the private data embedded in @tfm which is
* retrieved with crypto_tfm_ctx().
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>
2019-12-31 03:19:36 +00:00
*
* Return: 0 on success; -EINVAL on failure (only happens for bad key lengths)
*/
static int sm4_setkey(struct crypto_tfm *tfm, const u8 *in_key,
unsigned int key_len)
{
struct sm4_ctx *ctx = crypto_tfm_ctx(tfm);
return sm4_expandkey(ctx, in_key, key_len);
}
/* encrypt a block of text */
static void sm4_encrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
{
const struct sm4_ctx *ctx = crypto_tfm_ctx(tfm);
sm4_crypt_block(ctx->rkey_enc, out, in);
}
/* decrypt a block of text */
static void sm4_decrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
{
const struct sm4_ctx *ctx = crypto_tfm_ctx(tfm);
sm4_crypt_block(ctx->rkey_dec, out, in);
}
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 sm4_ctx),
.cra_module = THIS_MODULE,
.cra_u = {
.cipher = {
.cia_min_keysize = SM4_KEY_SIZE,
.cia_max_keysize = SM4_KEY_SIZE,
.cia_setkey = sm4_setkey,
.cia_encrypt = sm4_encrypt,
.cia_decrypt = 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");