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fs: cifs: move from the crypto cipher API to the new DES library interface

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Some legacy code in the CIFS driver uses single DES to calculate
some password hash, and uses the crypto cipher API to do so. Given
that there is no point in invoking an accelerated cipher for doing
56-bit symmetric encryption on a single 8-byte block of input, the
flexibility of the crypto cipher API does not add much value here,
and so we're much better off using a library call into the generic
C implementation.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Ard Biesheuvel 2019-08-15 12:01:12 +03:00 committed by Herbert Xu
parent 18fbe0da8e
commit 9a394d1208
3 changed files with 10 additions and 11 deletions
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2
fs/cifs/Kconfig
View File

@ -16,7 +16,7 @@ config CIFS
select CRYPTO_GCM
select CRYPTO_ECB
select CRYPTO_AES
select CRYPTO_DES
select CRYPTO_LIB_DES
select KEYS
help
This is the client VFS module for the SMB3 family of NAS protocols,

1
fs/cifs/cifsfs.c
View File

@ -1601,7 +1601,6 @@ MODULE_DESCRIPTION
("VFS to access SMB3 servers e.g. Samba, Macs, Azure and Windows (and "
"also older servers complying with the SNIA CIFS Specification)");
MODULE_VERSION(CIFS_VERSION);
MODULE_SOFTDEP("pre: des");
MODULE_SOFTDEP("pre: ecb");
MODULE_SOFTDEP("pre: hmac");
MODULE_SOFTDEP("pre: md4");

18
fs/cifs/smbencrypt.c
View File

@ -11,13 +11,14 @@
*/
#include <linux/crypto.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/fips.h>
#include <linux/fs.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/random.h>
#include <crypto/des.h>
#include "cifs_fs_sb.h"
#include "cifs_unicode.h"
#include "cifspdu.h"
@ -58,19 +59,18 @@ static int
smbhash(unsigned char *out, const unsigned char *in, unsigned char *key)
{
unsigned char key2[8];
struct crypto_cipher *tfm_des;
struct des_ctx ctx;
str_to_key(key, key2);
tfm_des = crypto_alloc_cipher("des", 0, 0);
if (IS_ERR(tfm_des)) {
cifs_dbg(VFS, "could not allocate des crypto API\n");
return PTR_ERR(tfm_des);
if (fips_enabled) {
cifs_dbg(VFS, "FIPS compliance enabled: DES not permitted\n");
return -ENOENT;
}
crypto_cipher_setkey(tfm_des, key2, 8);
crypto_cipher_encrypt_one(tfm_des, out, in);
crypto_free_cipher(tfm_des);
des_expand_key(&ctx, key2, DES_KEY_SIZE);
des_encrypt(&ctx, out, in);
memzero_explicit(&ctx, sizeof(ctx));
return 0;
}