smb2transport.c

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/*
 *   fs/cifs/smb2transport.c
 *
 *   Copyright (C) International Business Machines  Corp., 2002, 2011
 *                 Etersoft, 2012
 *   Author(s): Steve French ([email protected])
 *              Jeremy Allison ([email protected]) 2006
 *              Pavel Shilovsky ([email protected]) 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;
}