/*
 *   fs/cifs/smb2transport.c
 *
 *   Copyright (C) International Business Machines  Corp., 2002, 2011
 *                 Etersoft, 2012
 *   Author(s): Steve French (sfrench@us.ibm.com)
 *              Jeremy Allison (jra@samba.org) 2006
 *              Pavel Shilovsky (pshilovsky@samba.org) 2012
 *
 *   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/list.h>
#include <linux/wait.h>
#include <linux/net.h>
#include <linux/delay.h>
#include <linux/uaccess.h>
#include <asm/processor.h>
#include <linux/mempool.h>
#include <linux/highmem.h>
#include "smb2pdu.h"
#include "cifsglob.h"
#include "cifsproto.h"
#include "smb2proto.h"
#include "cifs_debug.h"
#include "smb2status.h"
#include "smb2glob.h"

static int
smb2_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
{
        int i, rc;
        unsigned char smb2_signature[SMB2_HMACSHA256_SIZE];
        unsigned char *sigptr = smb2_signature;
        struct kvec *iov = rqst->rq_iov;
        int n_vec = rqst->rq_nvec;
        struct smb2_hdr *smb2_pdu = (struct smb2_hdr *)iov[0].iov_base;

        memset(smb2_signature, 0x0, SMB2_HMACSHA256_SIZE);
        memset(smb2_pdu->Signature, 0x0, SMB2_SIGNATURE_SIZE);

        rc = crypto_shash_setkey(server->secmech.hmacsha256,
                server->session_key.response, SMB2_NTLMV2_SESSKEY_SIZE);
        if (rc) {
                cERROR(1, "%s: Could not update with response\n", __func__);
                return rc;
        }

        rc = crypto_shash_init(&server->secmech.sdeschmacsha256->shash);
        if (rc) {
                cERROR(1, "%s: Could not init md5\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.sdeschmacsha256->shash,
                                iov[i].iov_base + 4, iov[i].iov_len - 4);
                } else {
                        rc =
                        crypto_shash_update(
                                &server->secmech.sdeschmacsha256->shash,
                                iov[i].iov_base, iov[i].iov_len);
                }
                if (rc) {
                        cERROR(1, "%s: Could not update with payload\n",
                                                        __func__);
                        return rc;
                }
        }

        /* now hash over the rq_pages array */
        for (i = 0; i < rqst->rq_npages; i++) {
                struct kvec p_iov;

                cifs_rqst_page_to_kvec(rqst, i, &p_iov);
                crypto_shash_update(&server->secmech.sdeschmacsha256->shash,
                                        p_iov.iov_base, p_iov.iov_len);
                kunmap(rqst->rq_pages[i]);
        }

        rc = crypto_shash_final(&server->secmech.sdeschmacsha256->shash,
                                sigptr);
        if (rc)
                cERROR(1, "%s: Could not generate sha256 hash\n", __func__);

        memcpy(smb2_pdu->Signature, sigptr, SMB2_SIGNATURE_SIZE);

        return rc;
}

/* must be called with server->srv_mutex held */
static int
smb2_sign_rqst(struct smb_rqst *rqst, struct TCP_Server_Info *server)
{
        int rc = 0;
        struct smb2_hdr *smb2_pdu = rqst->rq_iov[0].iov_base;

        if (!(smb2_pdu->Flags & SMB2_FLAGS_SIGNED) ||
            server->tcpStatus == CifsNeedNegotiate)
                return rc;

        if (!server->session_estab) {
                strncpy(smb2_pdu->Signature, "BSRSPYL", 8);
                return rc;
        }

        rc = smb2_calc_signature(rqst, server);

        return rc;
}

int
smb2_verify_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
{
        unsigned int rc;
        char server_response_sig[16];
        struct smb2_hdr *smb2_pdu = (struct smb2_hdr *)rqst->rq_iov[0].iov_base;

        if ((smb2_pdu->Command == SMB2_NEGOTIATE) ||
            (smb2_pdu->Command == SMB2_OPLOCK_BREAK) ||
            (!server->session_estab))
                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(smb2_pdu->Signature, "BSRSPYL ", 8) == 0)
                cFYI(1, "dummy signature received for smb command 0x%x",
                        smb2_pdu->Command);

        /*
         * Save off the origiginal signature so we can modify the smb and check
         * our calculated signature against what the server sent.
         */
        memcpy(server_response_sig, smb2_pdu->Signature, SMB2_SIGNATURE_SIZE);

        memset(smb2_pdu->Signature, 0, SMB2_SIGNATURE_SIZE);

        mutex_lock(&server->srv_mutex);
        rc = smb2_calc_signature(rqst, server);
        mutex_unlock(&server->srv_mutex);

        if (rc)
                return rc;

        if (memcmp(server_response_sig, smb2_pdu->Signature,
                   SMB2_SIGNATURE_SIZE))
                return -EACCES;
        else
                return 0;
}

/*
 * Set message id for the request. Should be called after wait_for_free_request
 * and when srv_mutex is held.
 */
static inline void
smb2_seq_num_into_buf(struct TCP_Server_Info *server, struct smb2_hdr *hdr)
{
        hdr->MessageId = get_next_mid(server);
}

static struct mid_q_entry *
smb2_mid_entry_alloc(const struct smb2_hdr *smb_buffer,
                     struct TCP_Server_Info *server)
{
        struct mid_q_entry *temp;

        if (server == NULL) {
                cERROR(1, "Null TCP session in smb2_mid_entry_alloc");
                return NULL;
        }

        temp = mempool_alloc(cifs_mid_poolp, GFP_NOFS);
        if (temp == NULL)
                return temp;
        else {
                memset(temp, 0, sizeof(struct mid_q_entry));
                temp->mid = smb_buffer->MessageId;      /* always LE */
                temp->pid = current->pid;
                temp->command = smb_buffer->Command;    /* Always LE */
                temp->when_alloc = jiffies;
                temp->server = server;

                /*
                 * The default is for the mid to be synchronous, so the
                 * default callback just wakes up the current task.
                 */
                temp->callback = cifs_wake_up_task;
                temp->callback_data = current;
        }

        atomic_inc(&midCount);
        temp->mid_state = MID_REQUEST_ALLOCATED;
        return temp;
}

static int
smb2_get_mid_entry(struct cifs_ses *ses, struct smb2_hdr *buf,
                   struct mid_q_entry **mid)
{
        if (ses->server->tcpStatus == CifsExiting)
                return -ENOENT;

        if (ses->server->tcpStatus == CifsNeedReconnect) {
                cFYI(1, "tcp session dead - return to caller to retry");
                return -EAGAIN;
        }

        if (ses->status != CifsGood) {
                /* check if SMB2 session is bad because we are setting it up */
                if ((buf->Command != SMB2_SESSION_SETUP) &&
                    (buf->Command != SMB2_NEGOTIATE))
                        return -EAGAIN;
                /* else ok - we are setting up session */
        }
        *mid = smb2_mid_entry_alloc(buf, ses->server);
        if (*mid == NULL)
                return -ENOMEM;
        spin_lock(&GlobalMid_Lock);
        list_add_tail(&(*mid)->qhead, &ses->server->pending_mid_q);
        spin_unlock(&GlobalMid_Lock);
        return 0;
}

int
smb2_check_receive(struct mid_q_entry *mid, struct TCP_Server_Info *server,
                   bool log_error)
{
        unsigned int len = get_rfc1002_length(mid->resp_buf);
        struct kvec iov;
        struct smb_rqst rqst = { .rq_iov = &iov,
                                 .rq_nvec = 1 };

        iov.iov_base = (char *)mid->resp_buf;
        iov.iov_len = get_rfc1002_length(mid->resp_buf) + 4;

        dump_smb(mid->resp_buf, min_t(u32, 80, len));
        /* convert the length into a more usable form */
        if ((len > 24) &&
            (server->sec_mode & (SECMODE_SIGN_REQUIRED|SECMODE_SIGN_ENABLED))) {
                int rc;

                rc = smb2_verify_signature(&rqst, server);
                if (rc)
                        cERROR(1, "SMB signature verification returned error = "
                               "%d", rc);
        }

        return map_smb2_to_linux_error(mid->resp_buf, log_error);
}

struct mid_q_entry *
smb2_setup_request(struct cifs_ses *ses, struct smb_rqst *rqst)
{
        int rc;
        struct smb2_hdr *hdr = (struct smb2_hdr *)rqst->rq_iov[0].iov_base;
        struct mid_q_entry *mid;

        smb2_seq_num_into_buf(ses->server, hdr);

        rc = smb2_get_mid_entry(ses, hdr, &mid);
        if (rc)
                return ERR_PTR(rc);
        rc = smb2_sign_rqst(rqst, ses->server);
        if (rc) {
                cifs_delete_mid(mid);
                return ERR_PTR(rc);
        }
        return mid;
}

struct mid_q_entry *
smb2_setup_async_request(struct TCP_Server_Info *server, struct smb_rqst *rqst)
{
        int rc;
        struct smb2_hdr *hdr = (struct smb2_hdr *)rqst->rq_iov[0].iov_base;
        struct mid_q_entry *mid;

        smb2_seq_num_into_buf(server, hdr);

        mid = smb2_mid_entry_alloc(hdr, server);
        if (mid == NULL)
                return ERR_PTR(-ENOMEM);

        rc = smb2_sign_rqst(rqst, server);
        if (rc) {
                DeleteMidQEntry(mid);
                return ERR_PTR(rc);
        }

        return mid;
}