/*
   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 <crypto/skcipher.h>
#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_skcipher *tfm_des;
        struct scatterlist sgin, sgout;
        struct skcipher_request *req;

        str_to_key(key, key2);

        tfm_des = crypto_alloc_skcipher("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;
        }

        req = skcipher_request_alloc(tfm_des, GFP_KERNEL);
        if (!req) {
                rc = -ENOMEM;
                cifs_dbg(VFS, "could not allocate des crypto API\n");
                goto smbhash_free_skcipher;
        }

        crypto_skcipher_setkey(tfm_des, key2, 8);

        sg_init_one(&sgin, in, 8);
        sg_init_one(&sgout, out, 8);

        skcipher_request_set_callback(req, 0, NULL, NULL);
        skcipher_request_set_crypt(req, &sgin, &sgout, 8, NULL);

        rc = crypto_skcipher_encrypt(req);
        if (rc)
                cifs_dbg(VFS, "could not encrypt crypt key rc: %d\n", rc);

        skcipher_request_free(req);

smbhash_free_skcipher:
        crypto_free_skcipher(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;
}