Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input

[linux-btrfs-devel.git] / fs / cifs / cifsencrypt.c

/*
 *   fs/cifs/cifsencrypt.c
 *
 *   Copyright (C) International Business Machines  Corp., 2005,2006
 *   Author(s): Steve French (sfrench@us.ibm.com)
 *
 *   This library is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU Lesser General Public License as published
 *   by the Free Software Foundation; either version 2.1 of the License, or
 *   (at your option) any later version.
 *
 *   This library 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 Lesser General Public License for more details.
 *
 *   You should have received a copy of the GNU Lesser General Public License
 *   along with this library; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#include <linux/fs.h>
#include <linux/slab.h>
#include "cifspdu.h"
#include "cifsglob.h"
#include "cifs_debug.h"
#include "cifs_unicode.h"
#include "cifsproto.h"
#include "ntlmssp.h"
#include <linux/ctype.h>
#include <linux/random.h>

/*
 * Calculate and return the CIFS signature based on the mac key and SMB PDU.
 * The 16 byte signature must be allocated by the caller. Note we only use the
 * 1st eight bytes and that the smb header signature field on input contains
 * the sequence number before this function is called. Also, this function
 * should be called with the server->srv_mutex held.
 */
static int cifs_calculate_signature(const struct smb_hdr *cifs_pdu,
                                struct TCP_Server_Info *server, char *signature)
{
        int rc;

        if (cifs_pdu == NULL || signature == NULL || server == NULL)
                return -EINVAL;

        if (!server->secmech.sdescmd5) {
                cERROR(1, "%s: Can't generate signature\n", __func__);
                return -1;
        }

        rc = crypto_shash_init(&server->secmech.sdescmd5->shash);
        if (rc) {
                cERROR(1, "%s: Could not init md5\n", __func__);
                return rc;
        }

        rc = crypto_shash_update(&server->secmech.sdescmd5->shash,
                server->session_key.response, server->session_key.len);
        if (rc) {
                cERROR(1, "%s: Could not update with response\n", __func__);
                return rc;
        }

        rc = crypto_shash_update(&server->secmech.sdescmd5->shash,
                cifs_pdu->Protocol, be32_to_cpu(cifs_pdu->smb_buf_length));
        if (rc) {
                cERROR(1, "%s: Could not update with payload\n", __func__);
                return rc;
        }

        rc = crypto_shash_final(&server->secmech.sdescmd5->shash, signature);
        if (rc)
                cERROR(1, "%s: Could not generate md5 hash\n", __func__);

        return rc;
}

/* must be called with server->srv_mutex held */
int cifs_sign_smb(struct smb_hdr *cifs_pdu, struct TCP_Server_Info *server,
                  __u32 *pexpected_response_sequence_number)
{
        int rc = 0;
        char smb_signature[20];

        if ((cifs_pdu == NULL) || (server == NULL))
                return -EINVAL;

        if (!(cifs_pdu->Flags2 & SMBFLG2_SECURITY_SIGNATURE) ||
            server->tcpStatus == CifsNeedNegotiate)
                return rc;

        if (!server->session_estab) {
                strncpy(cifs_pdu->Signature.SecuritySignature, "BSRSPYL", 8);
                return rc;
        }

        cifs_pdu->Signature.Sequence.SequenceNumber =
                        cpu_to_le32(server->sequence_number);
        cifs_pdu->Signature.Sequence.Reserved = 0;

        *pexpected_response_sequence_number = server->sequence_number++;
        server->sequence_number++;

        rc = cifs_calculate_signature(cifs_pdu, server, smb_signature);
        if (rc)
                memset(cifs_pdu->Signature.SecuritySignature, 0, 8);
        else
                memcpy(cifs_pdu->Signature.SecuritySignature, smb_signature, 8);

        return rc;
}

static int cifs_calc_signature2(const struct kvec *iov, int n_vec,
                                struct TCP_Server_Info *server, char *signature)
{
        int i;
        int rc;

        if (iov == NULL || signature == NULL || server == NULL)
                return -EINVAL;

        if (!server->secmech.sdescmd5) {
                cERROR(1, "%s: Can't generate signature\n", __func__);
                return -1;
        }

        rc = crypto_shash_init(&server->secmech.sdescmd5->shash);
        if (rc) {
                cERROR(1, "%s: Could not init md5\n", __func__);
                return rc;
        }

        rc = crypto_shash_update(&server->secmech.sdescmd5->shash,
                server->session_key.response, server->session_key.len);
        if (rc) {
                cERROR(1, "%s: Could not update with response\n", __func__);
                return rc;
        }

        for (i = 0; i < n_vec; i++) {
                if (iov[i].iov_len == 0)
                        continue;
                if (iov[i].iov_base == NULL) {
                        cERROR(1, "null iovec entry");
                        return -EIO;
                }
                /* The first entry includes a length field (which does not get
                   signed that occupies the first 4 bytes before the header */
                if (i == 0) {
                        if (iov[0].iov_len <= 8) /* cmd field at offset 9 */
                                break; /* nothing to sign or corrupt header */
                        rc =
                        crypto_shash_update(&server->secmech.sdescmd5->shash,
                                iov[i].iov_base + 4, iov[i].iov_len - 4);
                } else {
                        rc =
                        crypto_shash_update(&server->secmech.sdescmd5->shash,
                                iov[i].iov_base, iov[i].iov_len);
                }
                if (rc) {
                        cERROR(1, "%s: Could not update with payload\n",
                                                        __func__);
                        return rc;
                }
        }

        rc = crypto_shash_final(&server->secmech.sdescmd5->shash, signature);
        if (rc)
                cERROR(1, "%s: Could not generate md5 hash\n", __func__);

        return rc;
}

/* must be called with server->srv_mutex held */
int cifs_sign_smb2(struct kvec *iov, int n_vec, struct TCP_Server_Info *server,
                   __u32 *pexpected_response_sequence_number)
{
        int rc = 0;
        char smb_signature[20];
        struct smb_hdr *cifs_pdu = iov[0].iov_base;

        if ((cifs_pdu == NULL) || (server == NULL))
                return -EINVAL;

        if (!(cifs_pdu->Flags2 & SMBFLG2_SECURITY_SIGNATURE) ||
            server->tcpStatus == CifsNeedNegotiate)
                return rc;

        if (!server->session_estab) {
                strncpy(cifs_pdu->Signature.SecuritySignature, "BSRSPYL", 8);
                return rc;
        }

        cifs_pdu->Signature.Sequence.SequenceNumber =
                                cpu_to_le32(server->sequence_number);
        cifs_pdu->Signature.Sequence.Reserved = 0;

        *pexpected_response_sequence_number = server->sequence_number++;
        server->sequence_number++;

        rc = cifs_calc_signature2(iov, n_vec, server, smb_signature);
        if (rc)
                memset(cifs_pdu->Signature.SecuritySignature, 0, 8);
        else
                memcpy(cifs_pdu->Signature.SecuritySignature, smb_signature, 8);

        return rc;
}

int cifs_verify_signature(struct smb_hdr *cifs_pdu,
                          struct TCP_Server_Info *server,
                          __u32 expected_sequence_number)
{
        unsigned int rc;
        char server_response_sig[8];
        char what_we_think_sig_should_be[20];

        if (cifs_pdu == NULL || server == NULL)
                return -EINVAL;

        if (!server->session_estab)
                return 0;

        if (cifs_pdu->Command == SMB_COM_LOCKING_ANDX) {
                struct smb_com_lock_req *pSMB =
                        (struct smb_com_lock_req *)cifs_pdu;
            if (pSMB->LockType & LOCKING_ANDX_OPLOCK_RELEASE)
                        return 0;
        }

        /* BB what if signatures are supposed to be on for session but
           server does not send one? BB */

        /* Do not need to verify session setups with signature "BSRSPYL "  */
        if (memcmp(cifs_pdu->Signature.SecuritySignature, "BSRSPYL ", 8) == 0)
                cFYI(1, "dummy signature received for smb command 0x%x",
                        cifs_pdu->Command);

        /* save off the origiginal signature so we can modify the smb and check
                its signature against what the server sent */
        memcpy(server_response_sig, cifs_pdu->Signature.SecuritySignature, 8);

        cifs_pdu->Signature.Sequence.SequenceNumber =
                                        cpu_to_le32(expected_sequence_number);
        cifs_pdu->Signature.Sequence.Reserved = 0;

        mutex_lock(&server->srv_mutex);
        rc = cifs_calculate_signature(cifs_pdu, server,
                what_we_think_sig_should_be);
        mutex_unlock(&server->srv_mutex);

        if (rc)
                return rc;

/*      cifs_dump_mem("what we think it should be: ",
                      what_we_think_sig_should_be, 16); */

        if (memcmp(server_response_sig, what_we_think_sig_should_be, 8))
                return -EACCES;
        else
                return 0;

}

/* first calculate 24 bytes ntlm response and then 16 byte session key */
int setup_ntlm_response(struct cifs_ses *ses)
{
        int rc = 0;
        unsigned int temp_len = CIFS_SESS_KEY_SIZE + CIFS_AUTH_RESP_SIZE;
        char temp_key[CIFS_SESS_KEY_SIZE];

        if (!ses)
                return -EINVAL;

        ses->auth_key.response = kmalloc(temp_len, GFP_KERNEL);
        if (!ses->auth_key.response) {
                cERROR(1, "NTLM can't allocate (%u bytes) memory", temp_len);
                return -ENOMEM;
        }
        ses->auth_key.len = temp_len;

        rc = SMBNTencrypt(ses->password, ses->server->cryptkey,
                        ses->auth_key.response + CIFS_SESS_KEY_SIZE);
        if (rc) {
                cFYI(1, "%s Can't generate NTLM response, error: %d",
                        __func__, rc);
                return rc;
        }

        rc = E_md4hash(ses->password, temp_key);
        if (rc) {
                cFYI(1, "%s Can't generate NT hash, error: %d", __func__, rc);
                return rc;
        }

        rc = mdfour(ses->auth_key.response, temp_key, CIFS_SESS_KEY_SIZE);
        if (rc)
                cFYI(1, "%s Can't generate NTLM session key, error: %d",
                        __func__, rc);

        return rc;
}

#ifdef CONFIG_CIFS_WEAK_PW_HASH
int calc_lanman_hash(const char *password, const char *cryptkey, bool encrypt,
                        char *lnm_session_key)
{
        int i;
        int rc;
        char password_with_pad[CIFS_ENCPWD_SIZE];

        memset(password_with_pad, 0, CIFS_ENCPWD_SIZE);
        if (password)
                strncpy(password_with_pad, password, CIFS_ENCPWD_SIZE);

        if (!encrypt && global_secflags & CIFSSEC_MAY_PLNTXT) {
                memset(lnm_session_key, 0, CIFS_SESS_KEY_SIZE);
                memcpy(lnm_session_key, password_with_pad,
                        CIFS_ENCPWD_SIZE);
                return 0;
        }

        /* calculate old style session key */
        /* calling toupper is less broken than repeatedly
        calling nls_toupper would be since that will never
        work for UTF8, but neither handles multibyte code pages
        but the only alternative would be converting to UCS-16 (Unicode)
        (using a routine something like UniStrupr) then
        uppercasing and then converting back from Unicode - which
        would only worth doing it if we knew it were utf8. Basically
        utf8 and other multibyte codepages each need their own strupper
        function since a byte at a time will ont work. */

        for (i = 0; i < CIFS_ENCPWD_SIZE; i++)
                password_with_pad[i] = toupper(password_with_pad[i]);

        rc = SMBencrypt(password_with_pad, cryptkey, lnm_session_key);

        return rc;
}
#endif /* CIFS_WEAK_PW_HASH */

/* Build a proper attribute value/target info pairs blob.
 * Fill in netbios and dns domain name and workstation name
 * and client time (total five av pairs and + one end of fields indicator.
 * Allocate domain name which gets freed when session struct is deallocated.
 */
static int
build_avpair_blob(struct cifs_ses *ses, const struct nls_table *nls_cp)
{
        unsigned int dlen;
        unsigned int size = 2 * sizeof(struct ntlmssp2_name);
        char *defdmname = "WORKGROUP";
        unsigned char *blobptr;
        struct ntlmssp2_name *attrptr;

        if (!ses->domainName) {
                ses->domainName = kstrdup(defdmname, GFP_KERNEL);
                if (!ses->domainName)
                        return -ENOMEM;
        }

        dlen = strlen(ses->domainName);

        /*
         * The length of this blob is two times the size of a
         * structure (av pair) which holds name/size
         * ( for NTLMSSP_AV_NB_DOMAIN_NAME followed by NTLMSSP_AV_EOL ) +
         * unicode length of a netbios domain name
         */
        ses->auth_key.len = size + 2 * dlen;
        ses->auth_key.response = kzalloc(ses->auth_key.len, GFP_KERNEL);
        if (!ses->auth_key.response) {
                ses->auth_key.len = 0;
                cERROR(1, "Challenge target info allocation failure");
                return -ENOMEM;
        }

        blobptr = ses->auth_key.response;
        attrptr = (struct ntlmssp2_name *) blobptr;

        /*
         * As defined in MS-NTLM 3.3.2, just this av pair field
         * is sufficient as part of the temp
         */
        attrptr->type = cpu_to_le16(NTLMSSP_AV_NB_DOMAIN_NAME);
        attrptr->length = cpu_to_le16(2 * dlen);
        blobptr = (unsigned char *)attrptr + sizeof(struct ntlmssp2_name);
        cifs_strtoUCS((__le16 *)blobptr, ses->domainName, dlen, nls_cp);

        return 0;
}

/* Server has provided av pairs/target info in the type 2 challenge
 * packet and we have plucked it and stored within smb session.
 * We parse that blob here to find netbios domain name to be used
 * as part of ntlmv2 authentication (in Target String), if not already
 * specified on the command line.
 * If this function returns without any error but without fetching
 * domain name, authentication may fail against some server but
 * may not fail against other (those who are not very particular
 * about target string i.e. for some, just user name might suffice.
 */
static int
find_domain_name(struct cifs_ses *ses, const struct nls_table *nls_cp)
{
        unsigned int attrsize;
        unsigned int type;
        unsigned int onesize = sizeof(struct ntlmssp2_name);
        unsigned char *blobptr;
        unsigned char *blobend;
        struct ntlmssp2_name *attrptr;

        if (!ses->auth_key.len || !ses->auth_key.response)
                return 0;

        blobptr = ses->auth_key.response;
        blobend = blobptr + ses->auth_key.len;

        while (blobptr + onesize < blobend) {
                attrptr = (struct ntlmssp2_name *) blobptr;
                type = le16_to_cpu(attrptr->type);
                if (type == NTLMSSP_AV_EOL)
                        break;
                blobptr += 2; /* advance attr type */
                attrsize = le16_to_cpu(attrptr->length);
                blobptr += 2; /* advance attr size */
                if (blobptr + attrsize > blobend)
                        break;
                if (type == NTLMSSP_AV_NB_DOMAIN_NAME) {
                        if (!attrsize)
                                break;
                        if (!ses->domainName) {
                                ses->domainName =
                                        kmalloc(attrsize + 1, GFP_KERNEL);
                                if (!ses->domainName)
                                                return -ENOMEM;
                                cifs_from_ucs2(ses->domainName,
                                        (__le16 *)blobptr, attrsize, attrsize,
                                        nls_cp, false);
                                break;
                        }
                }
                blobptr += attrsize; /* advance attr  value */
        }

        return 0;
}

static int calc_ntlmv2_hash(struct cifs_ses *ses, char *ntlmv2_hash,
                            const struct nls_table *nls_cp)
{
        int rc = 0;
        int len;
        char nt_hash[CIFS_NTHASH_SIZE];
        wchar_t *user;
        wchar_t *domain;
        wchar_t *server;

        if (!ses->server->secmech.sdeschmacmd5) {
                cERROR(1, "calc_ntlmv2_hash: can't generate ntlmv2 hash\n");
                return -1;
        }

        /* calculate md4 hash of password */
        E_md4hash(ses->password, nt_hash);

        rc = crypto_shash_setkey(ses->server->secmech.hmacmd5, nt_hash,
                                CIFS_NTHASH_SIZE);
        if (rc) {
                cERROR(1, "%s: Could not set NT Hash as a key", __func__);
                return rc;
        }

        rc = crypto_shash_init(&ses->server->secmech.sdeschmacmd5->shash);
        if (rc) {
                cERROR(1, "calc_ntlmv2_hash: could not init hmacmd5\n");
                return rc;
        }

        /* convert ses->user_name to unicode and uppercase */
        len = strlen(ses->user_name);
        user = kmalloc(2 + (len * 2), GFP_KERNEL);
        if (user == NULL) {
                cERROR(1, "calc_ntlmv2_hash: user mem alloc failure\n");
                rc = -ENOMEM;
                return rc;
        }
        len = cifs_strtoUCS((__le16 *)user, ses->user_name, len, nls_cp);
        UniStrupr(user);

        rc = crypto_shash_update(&ses->server->secmech.sdeschmacmd5->shash,
                                (char *)user, 2 * len);
        kfree(user);
        if (rc) {
                cERROR(1, "%s: Could not update with user\n", __func__);
                return rc;
        }

        /* convert ses->domainName to unicode and uppercase */
        if (ses->domainName) {
                len = strlen(ses->domainName);

                domain = kmalloc(2 + (len * 2), GFP_KERNEL);
                if (domain == NULL) {
                        cERROR(1, "calc_ntlmv2_hash: domain mem alloc failure");
                        rc = -ENOMEM;
                        return rc;
                }
                len = cifs_strtoUCS((__le16 *)domain, ses->domainName, len,
                                        nls_cp);
                rc =
                crypto_shash_update(&ses->server->secmech.sdeschmacmd5->shash,
                                        (char *)domain, 2 * len);
                kfree(domain);
                if (rc) {
                        cERROR(1, "%s: Could not update with domain\n",
                                                                __func__);
                        return rc;
                }
        } else if (ses->serverName) {
                len = strlen(ses->serverName);

                server = kmalloc(2 + (len * 2), GFP_KERNEL);
                if (server == NULL) {
                        cERROR(1, "calc_ntlmv2_hash: server mem alloc failure");
                        rc = -ENOMEM;
                        return rc;
                }
                len = cifs_strtoUCS((__le16 *)server, ses->serverName, len,
                                        nls_cp);
                rc =
                crypto_shash_update(&ses->server->secmech.sdeschmacmd5->shash,
                                        (char *)server, 2 * len);
                kfree(server);
                if (rc) {
                        cERROR(1, "%s: Could not update with server\n",
                                                                __func__);
                        return rc;
                }
        }

        rc = crypto_shash_final(&ses->server->secmech.sdeschmacmd5->shash,
                                        ntlmv2_hash);
        if (rc)
                cERROR(1, "%s: Could not generate md5 hash\n", __func__);

        return rc;
}

static int
CalcNTLMv2_response(const struct cifs_ses *ses, char *ntlmv2_hash)
{
        int rc;
        unsigned int offset = CIFS_SESS_KEY_SIZE + 8;

        if (!ses->server->secmech.sdeschmacmd5) {
                cERROR(1, "calc_ntlmv2_hash: can't generate ntlmv2 hash\n");
                return -1;
        }

        rc = crypto_shash_setkey(ses->server->secmech.hmacmd5,
                                ntlmv2_hash, CIFS_HMAC_MD5_HASH_SIZE);
        if (rc) {
                cERROR(1, "%s: Could not set NTLMV2 Hash as a key", __func__);
                return rc;
        }

        rc = crypto_shash_init(&ses->server->secmech.sdeschmacmd5->shash);
        if (rc) {
                cERROR(1, "CalcNTLMv2_response: could not init hmacmd5");
                return rc;
        }

        if (ses->server->secType == RawNTLMSSP)
                memcpy(ses->auth_key.response + offset,
                        ses->ntlmssp->cryptkey, CIFS_SERVER_CHALLENGE_SIZE);
        else
                memcpy(ses->auth_key.response + offset,
                        ses->server->cryptkey, CIFS_SERVER_CHALLENGE_SIZE);
        rc = crypto_shash_update(&ses->server->secmech.sdeschmacmd5->shash,
                ses->auth_key.response + offset, ses->auth_key.len - offset);
        if (rc) {
                cERROR(1, "%s: Could not update with response\n", __func__);
                return rc;
        }

        rc = crypto_shash_final(&ses->server->secmech.sdeschmacmd5->shash,
                ses->auth_key.response + CIFS_SESS_KEY_SIZE);
        if (rc)
                cERROR(1, "%s: Could not generate md5 hash\n", __func__);

        return rc;
}


int
setup_ntlmv2_rsp(struct cifs_ses *ses, const struct nls_table *nls_cp)
{
        int rc;
        int baselen;
        unsigned int tilen;
        struct ntlmv2_resp *buf;
        char ntlmv2_hash[16];
        unsigned char *tiblob = NULL; /* target info blob */

        if (ses->server->secType == RawNTLMSSP) {
                if (!ses->domainName) {
                        rc = find_domain_name(ses, nls_cp);
                        if (rc) {
                                cERROR(1, "error %d finding domain name", rc);
                                goto setup_ntlmv2_rsp_ret;
                        }
                }
        } else {
                rc = build_avpair_blob(ses, nls_cp);
                if (rc) {
                        cERROR(1, "error %d building av pair blob", rc);
                        goto setup_ntlmv2_rsp_ret;
                }
        }

        baselen = CIFS_SESS_KEY_SIZE + sizeof(struct ntlmv2_resp);
        tilen = ses->auth_key.len;
        tiblob = ses->auth_key.response;

        ses->auth_key.response = kmalloc(baselen + tilen, GFP_KERNEL);
        if (!ses->auth_key.response) {
                rc = ENOMEM;
                ses->auth_key.len = 0;
                cERROR(1, "%s: Can't allocate auth blob", __func__);
                goto setup_ntlmv2_rsp_ret;
        }
        ses->auth_key.len += baselen;

        buf = (struct ntlmv2_resp *)
                        (ses->auth_key.response + CIFS_SESS_KEY_SIZE);
        buf->blob_signature = cpu_to_le32(0x00000101);
        buf->reserved = 0;
        buf->time = cpu_to_le64(cifs_UnixTimeToNT(CURRENT_TIME));
        get_random_bytes(&buf->client_chal, sizeof(buf->client_chal));
        buf->reserved2 = 0;

        memcpy(ses->auth_key.response + baselen, tiblob, tilen);

        /* calculate ntlmv2_hash */
        rc = calc_ntlmv2_hash(ses, ntlmv2_hash, nls_cp);
        if (rc) {
                cERROR(1, "could not get v2 hash rc %d", rc);
                goto setup_ntlmv2_rsp_ret;
        }

        /* calculate first part of the client response (CR1) */
        rc = CalcNTLMv2_response(ses, ntlmv2_hash);
        if (rc) {
                cERROR(1, "Could not calculate CR1  rc: %d", rc);
                goto setup_ntlmv2_rsp_ret;
        }

        /* now calculate the session key for NTLMv2 */
        rc = crypto_shash_setkey(ses->server->secmech.hmacmd5,
                ntlmv2_hash, CIFS_HMAC_MD5_HASH_SIZE);
        if (rc) {
                cERROR(1, "%s: Could not set NTLMV2 Hash as a key", __func__);
                goto setup_ntlmv2_rsp_ret;
        }

        rc = crypto_shash_init(&ses->server->secmech.sdeschmacmd5->shash);
        if (rc) {
                cERROR(1, "%s: Could not init hmacmd5\n", __func__);
                goto setup_ntlmv2_rsp_ret;
        }

        rc = crypto_shash_update(&ses->server->secmech.sdeschmacmd5->shash,
                ses->auth_key.response + CIFS_SESS_KEY_SIZE,
                CIFS_HMAC_MD5_HASH_SIZE);
        if (rc) {
                cERROR(1, "%s: Could not update with response\n", __func__);
                goto setup_ntlmv2_rsp_ret;
        }

        rc = crypto_shash_final(&ses->server->secmech.sdeschmacmd5->shash,
                ses->auth_key.response);
        if (rc)
                cERROR(1, "%s: Could not generate md5 hash\n", __func__);

setup_ntlmv2_rsp_ret:
        kfree(tiblob);

        return rc;
}

int
calc_seckey(struct cifs_ses *ses)
{
        int rc;
        struct crypto_blkcipher *tfm_arc4;
        struct scatterlist sgin, sgout;
        struct blkcipher_desc desc;
        unsigned char sec_key[CIFS_SESS_KEY_SIZE]; /* a nonce */

        get_random_bytes(sec_key, CIFS_SESS_KEY_SIZE);

        tfm_arc4 = crypto_alloc_blkcipher("ecb(arc4)", 0, CRYPTO_ALG_ASYNC);
        if (IS_ERR(tfm_arc4)) {
                rc = PTR_ERR(tfm_arc4);
                cERROR(1, "could not allocate crypto API arc4\n");
                return rc;
        }

        desc.tfm = tfm_arc4;

        rc = crypto_blkcipher_setkey(tfm_arc4, ses->auth_key.response,
                                        CIFS_SESS_KEY_SIZE);
        if (rc) {
                cERROR(1, "%s: Could not set response as a key", __func__);
                return rc;
        }

        sg_init_one(&sgin, sec_key, CIFS_SESS_KEY_SIZE);
        sg_init_one(&sgout, ses->ntlmssp->ciphertext, CIFS_CPHTXT_SIZE);

        rc = crypto_blkcipher_encrypt(&desc, &sgout, &sgin, CIFS_CPHTXT_SIZE);
        if (rc) {
                cERROR(1, "could not encrypt session key rc: %d\n", rc);
                crypto_free_blkcipher(tfm_arc4);
                return rc;
        }

        /* make secondary_key/nonce as session key */
        memcpy(ses->auth_key.response, sec_key, CIFS_SESS_KEY_SIZE);
        /* and make len as that of session key only */
        ses->auth_key.len = CIFS_SESS_KEY_SIZE;

        crypto_free_blkcipher(tfm_arc4);

        return rc;
}

void
cifs_crypto_shash_release(struct TCP_Server_Info *server)
{
        if (server->secmech.md5)
                crypto_free_shash(server->secmech.md5);

        if (server->secmech.hmacmd5)
                crypto_free_shash(server->secmech.hmacmd5);

        kfree(server->secmech.sdeschmacmd5);

        kfree(server->secmech.sdescmd5);
}

int
cifs_crypto_shash_allocate(struct TCP_Server_Info *server)
{
        int rc;
        unsigned int size;

        server->secmech.hmacmd5 = crypto_alloc_shash("hmac(md5)", 0, 0);
        if (IS_ERR(server->secmech.hmacmd5)) {
                cERROR(1, "could not allocate crypto hmacmd5\n");
                return PTR_ERR(server->secmech.hmacmd5);
        }

        server->secmech.md5 = crypto_alloc_shash("md5", 0, 0);
        if (IS_ERR(server->secmech.md5)) {
                cERROR(1, "could not allocate crypto md5\n");
                rc = PTR_ERR(server->secmech.md5);
                goto crypto_allocate_md5_fail;
        }

        size = sizeof(struct shash_desc) +
                        crypto_shash_descsize(server->secmech.hmacmd5);
        server->secmech.sdeschmacmd5 = kmalloc(size, GFP_KERNEL);
        if (!server->secmech.sdeschmacmd5) {
                cERROR(1, "cifs_crypto_shash_allocate: can't alloc hmacmd5\n");
                rc = -ENOMEM;
                goto crypto_allocate_hmacmd5_sdesc_fail;
        }
        server->secmech.sdeschmacmd5->shash.tfm = server->secmech.hmacmd5;
        server->secmech.sdeschmacmd5->shash.flags = 0x0;


        size = sizeof(struct shash_desc) +
                        crypto_shash_descsize(server->secmech.md5);
        server->secmech.sdescmd5 = kmalloc(size, GFP_KERNEL);
        if (!server->secmech.sdescmd5) {
                cERROR(1, "cifs_crypto_shash_allocate: can't alloc md5\n");
                rc = -ENOMEM;
                goto crypto_allocate_md5_sdesc_fail;
        }
        server->secmech.sdescmd5->shash.tfm = server->secmech.md5;
        server->secmech.sdescmd5->shash.flags = 0x0;

        return 0;

crypto_allocate_md5_sdesc_fail:
        kfree(server->secmech.sdeschmacmd5);

crypto_allocate_hmacmd5_sdesc_fail:
        crypto_free_shash(server->secmech.md5);

crypto_allocate_md5_fail:
        crypto_free_shash(server->secmech.hmacmd5);

        return rc;
}