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crypto: des_generic - Forbid 2-key in 3DES and add helpers

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This patch adds a requirement to the generic 3DES implementation
such that 2-key 3DES (K1 == K3) is no longer allowed in FIPS mode.

We will also provide helpers that may be used by drivers that
implement 3DES to make the same check.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Herbert Xu 2019-04-11 16:50:56 +08:00
parent 694e0db660
commit d7198ce46d
2 changed files with 47 additions and 7 deletions
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11
crypto/des_generic.c
View File

@ -862,14 +862,11 @@ static void des_decrypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
int __des3_ede_setkey(u32 *expkey, u32 *flags, const u8 *key,
unsigned int keylen)
{
const u32 *K = (const u32 *)key;
int err;
if (unlikely(!((K[0] ^ K[2]) | (K[1] ^ K[3])) ||
!((K[2] ^ K[4]) | (K[3] ^ K[5]))) &&
(*flags & CRYPTO_TFM_REQ_FORBID_WEAK_KEYS)) {
*flags |= CRYPTO_TFM_RES_WEAK_KEY;
return -EINVAL;
}
err = __des3_verify_key(flags, key);
if (unlikely(err))
return err;
des_ekey(expkey, key); expkey += DES_EXPKEY_WORDS; key += DES_KEY_SIZE;
dkey(expkey, key); expkey += DES_EXPKEY_WORDS; key += DES_KEY_SIZE;

43
include/crypto/des.h
View File

@ -6,6 +6,11 @@
#ifndef __CRYPTO_DES_H
#define __CRYPTO_DES_H
#include <crypto/skcipher.h>
#include <linux/compiler.h>
#include <linux/fips.h>
#include <linux/string.h>
#define DES_KEY_SIZE 8
#define DES_EXPKEY_WORDS 32
#define DES_BLOCK_SIZE 8
@ -14,6 +19,44 @@
#define DES3_EDE_EXPKEY_WORDS (3 * DES_EXPKEY_WORDS)
#define DES3_EDE_BLOCK_SIZE DES_BLOCK_SIZE
static inline int __des3_verify_key(u32 *flags, const u8 *key)
{
int err = -EINVAL;
u32 K[6];
memcpy(K, key, DES3_EDE_KEY_SIZE);
if (unlikely(!((K[0] ^ K[2]) | (K[1] ^ K[3])) ||
!((K[2] ^ K[4]) | (K[3] ^ K[5]))) &&
(fips_enabled ||
(*flags & CRYPTO_TFM_REQ_FORBID_WEAK_KEYS)))
goto bad;
if (unlikely(!((K[0] ^ K[4]) | (K[1] ^ K[5]))) && fips_enabled)
goto bad;
err = 0;
out:
memzero_explicit(K, DES3_EDE_KEY_SIZE);
return err;
bad:
*flags |= CRYPTO_TFM_RES_WEAK_KEY;
goto out;
}
static inline int des3_verify_key(struct crypto_skcipher *tfm, const u8 *key)
{
u32 flags;
int err;
flags = crypto_skcipher_get_flags(tfm);
err = __des3_verify_key(&flags, key);
crypto_skcipher_set_flags(tfm, flags);
return err;
}
extern unsigned long des_ekey(u32 *pe, const u8 *k);