linux-hardened/fs/cifs/smbencrypt.c
Giel van Schijndel f99dbfa4b3 cifs: use memzero_explicit to clear stack buffer
When leaving a function use memzero_explicit instead of memset(0) to
clear stack allocated buffers. memset(0) may be optimized away.

This particular buffer is highly likely to contain sensitive data which
we shouldn't leak (it's named 'passwd' after all).

Signed-off-by: Giel van Schijndel <me@mortis.eu>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Reported-at: http://www.viva64.com/en/b/0299/
Reported-by: Andrey Karpov
Reported-by: Svyatoslav Razmyslov
Signed-off-by: Steve French <steve.french@primarydata.com>
2015-01-19 15:32:13 -06:00

249 lines
6 KiB
C

/*
Unix SMB/Netbios implementation.
Version 1.9.
SMB parameters and setup
Copyright (C) Andrew Tridgell 1992-2000
Copyright (C) Luke Kenneth Casson Leighton 1996-2000
Modified by Jeremy Allison 1995.
Copyright (C) Andrew Bartlett <abartlet@samba.org> 2002-2003
Modified by Steve French (sfrench@us.ibm.com) 2002-2003
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.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/random.h>
#include "cifs_fs_sb.h"
#include "cifs_unicode.h"
#include "cifspdu.h"
#include "cifsglob.h"
#include "cifs_debug.h"
#include "cifsproto.h"
#ifndef false
#define false 0
#endif
#ifndef true
#define true 1
#endif
/* following came from the other byteorder.h to avoid include conflicts */
#define CVAL(buf,pos) (((unsigned char *)(buf))[pos])
#define SSVALX(buf,pos,val) (CVAL(buf,pos)=(val)&0xFF,CVAL(buf,pos+1)=(val)>>8)
#define SSVAL(buf,pos,val) SSVALX((buf),(pos),((__u16)(val)))
static void
str_to_key(unsigned char *str, unsigned char *key)
{
int i;
key[0] = str[0] >> 1;
key[1] = ((str[0] & 0x01) << 6) | (str[1] >> 2);
key[2] = ((str[1] & 0x03) << 5) | (str[2] >> 3);
key[3] = ((str[2] & 0x07) << 4) | (str[3] >> 4);
key[4] = ((str[3] & 0x0F) << 3) | (str[4] >> 5);
key[5] = ((str[4] & 0x1F) << 2) | (str[5] >> 6);
key[6] = ((str[5] & 0x3F) << 1) | (str[6] >> 7);
key[7] = str[6] & 0x7F;
for (i = 0; i < 8; i++)
key[i] = (key[i] << 1);
}
static int
smbhash(unsigned char *out, const unsigned char *in, unsigned char *key)
{
int rc;
unsigned char key2[8];
struct crypto_blkcipher *tfm_des;
struct scatterlist sgin, sgout;
struct blkcipher_desc desc;
str_to_key(key, key2);
tfm_des = crypto_alloc_blkcipher("ecb(des)", 0, CRYPTO_ALG_ASYNC);
if (IS_ERR(tfm_des)) {
rc = PTR_ERR(tfm_des);
cifs_dbg(VFS, "could not allocate des crypto API\n");
goto smbhash_err;
}
desc.tfm = tfm_des;
crypto_blkcipher_setkey(tfm_des, key2, 8);
sg_init_one(&sgin, in, 8);
sg_init_one(&sgout, out, 8);
rc = crypto_blkcipher_encrypt(&desc, &sgout, &sgin, 8);
if (rc)
cifs_dbg(VFS, "could not encrypt crypt key rc: %d\n", rc);
crypto_free_blkcipher(tfm_des);
smbhash_err:
return rc;
}
static int
E_P16(unsigned char *p14, unsigned char *p16)
{
int rc;
unsigned char sp8[8] =
{ 0x4b, 0x47, 0x53, 0x21, 0x40, 0x23, 0x24, 0x25 };
rc = smbhash(p16, sp8, p14);
if (rc)
return rc;
rc = smbhash(p16 + 8, sp8, p14 + 7);
return rc;
}
static int
E_P24(unsigned char *p21, const unsigned char *c8, unsigned char *p24)
{
int rc;
rc = smbhash(p24, c8, p21);
if (rc)
return rc;
rc = smbhash(p24 + 8, c8, p21 + 7);
if (rc)
return rc;
rc = smbhash(p24 + 16, c8, p21 + 14);
return rc;
}
/* produce a md4 message digest from data of length n bytes */
int
mdfour(unsigned char *md4_hash, unsigned char *link_str, int link_len)
{
int rc;
unsigned int size;
struct crypto_shash *md4;
struct sdesc *sdescmd4;
md4 = crypto_alloc_shash("md4", 0, 0);
if (IS_ERR(md4)) {
rc = PTR_ERR(md4);
cifs_dbg(VFS, "%s: Crypto md4 allocation error %d\n",
__func__, rc);
return rc;
}
size = sizeof(struct shash_desc) + crypto_shash_descsize(md4);
sdescmd4 = kmalloc(size, GFP_KERNEL);
if (!sdescmd4) {
rc = -ENOMEM;
goto mdfour_err;
}
sdescmd4->shash.tfm = md4;
sdescmd4->shash.flags = 0x0;
rc = crypto_shash_init(&sdescmd4->shash);
if (rc) {
cifs_dbg(VFS, "%s: Could not init md4 shash\n", __func__);
goto mdfour_err;
}
rc = crypto_shash_update(&sdescmd4->shash, link_str, link_len);
if (rc) {
cifs_dbg(VFS, "%s: Could not update with link_str\n", __func__);
goto mdfour_err;
}
rc = crypto_shash_final(&sdescmd4->shash, md4_hash);
if (rc)
cifs_dbg(VFS, "%s: Could not generate md4 hash\n", __func__);
mdfour_err:
crypto_free_shash(md4);
kfree(sdescmd4);
return rc;
}
/*
This implements the X/Open SMB password encryption
It takes a password, a 8 byte "crypt key" and puts 24 bytes of
encrypted password into p24 */
/* Note that password must be uppercased and null terminated */
int
SMBencrypt(unsigned char *passwd, const unsigned char *c8, unsigned char *p24)
{
int rc;
unsigned char p14[14], p16[16], p21[21];
memset(p14, '\0', 14);
memset(p16, '\0', 16);
memset(p21, '\0', 21);
memcpy(p14, passwd, 14);
rc = E_P16(p14, p16);
if (rc)
return rc;
memcpy(p21, p16, 16);
rc = E_P24(p21, c8, p24);
return rc;
}
/*
* Creates the MD4 Hash of the users password in NT UNICODE.
*/
int
E_md4hash(const unsigned char *passwd, unsigned char *p16,
const struct nls_table *codepage)
{
int rc;
int len;
__le16 wpwd[129];
/* Password cannot be longer than 128 characters */
if (passwd) /* Password must be converted to NT unicode */
len = cifs_strtoUTF16(wpwd, passwd, 128, codepage);
else {
len = 0;
*wpwd = 0; /* Ensure string is null terminated */
}
rc = mdfour(p16, (unsigned char *) wpwd, len * sizeof(__le16));
memzero_explicit(wpwd, sizeof(wpwd));
return rc;
}
/* Does the NT MD4 hash then des encryption. */
int
SMBNTencrypt(unsigned char *passwd, unsigned char *c8, unsigned char *p24,
const struct nls_table *codepage)
{
int rc;
unsigned char p16[16], p21[21];
memset(p16, '\0', 16);
memset(p21, '\0', 21);
rc = E_md4hash(passwd, p16, codepage);
if (rc) {
cifs_dbg(FYI, "%s Can't generate NT hash, error: %d\n",
__func__, rc);
return rc;
}
memcpy(p21, p16, 16);
rc = E_P24(p21, c8, p24);
return rc;
}