linux/fs/cifs/smb2misc.c
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   1/*
   2 *   fs/cifs/smb2misc.c
   3 *
   4 *   Copyright (C) International Business Machines  Corp., 2002,2011
   5 *                 Etersoft, 2012
   6 *   Author(s): Steve French (sfrench@us.ibm.com)
   7 *              Pavel Shilovsky (pshilovsky@samba.org) 2012
   8 *
   9 *   This library is free software; you can redistribute it and/or modify
  10 *   it under the terms of the GNU Lesser General Public License as published
  11 *   by the Free Software Foundation; either version 2.1 of the License, or
  12 *   (at your option) any later version.
  13 *
  14 *   This library is distributed in the hope that it will be useful,
  15 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  16 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
  17 *   the GNU Lesser General Public License for more details.
  18 *
  19 *   You should have received a copy of the GNU Lesser General Public License
  20 *   along with this library; if not, write to the Free Software
  21 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  22 */
  23#include <linux/ctype.h>
  24#include "smb2pdu.h"
  25#include "cifsglob.h"
  26#include "cifsproto.h"
  27#include "smb2proto.h"
  28#include "cifs_debug.h"
  29#include "cifs_unicode.h"
  30#include "smb2status.h"
  31
  32static int
  33check_smb2_hdr(struct smb2_hdr *hdr, __u64 mid)
  34{
  35        /*
  36         * Make sure that this really is an SMB, that it is a response,
  37         * and that the message ids match.
  38         */
  39        if ((*(__le32 *)hdr->ProtocolId == SMB2_PROTO_NUMBER) &&
  40            (mid == hdr->MessageId)) {
  41                if (hdr->Flags & SMB2_FLAGS_SERVER_TO_REDIR)
  42                        return 0;
  43                else {
  44                        /* only one valid case where server sends us request */
  45                        if (hdr->Command == SMB2_OPLOCK_BREAK)
  46                                return 0;
  47                        else
  48                                cERROR(1, "Received Request not response");
  49                }
  50        } else { /* bad signature or mid */
  51                if (*(__le32 *)hdr->ProtocolId != SMB2_PROTO_NUMBER)
  52                        cERROR(1, "Bad protocol string signature header %x",
  53                                  *(unsigned int *) hdr->ProtocolId);
  54                if (mid != hdr->MessageId)
  55                        cERROR(1, "Mids do not match: %llu and %llu", mid,
  56                                  hdr->MessageId);
  57        }
  58        cERROR(1, "Bad SMB detected. The Mid=%llu", hdr->MessageId);
  59        return 1;
  60}
  61
  62/*
  63 *  The following table defines the expected "StructureSize" of SMB2 responses
  64 *  in order by SMB2 command.  This is similar to "wct" in SMB/CIFS responses.
  65 *
  66 *  Note that commands are defined in smb2pdu.h in le16 but the array below is
  67 *  indexed by command in host byte order
  68 */
  69static const __le16 smb2_rsp_struct_sizes[NUMBER_OF_SMB2_COMMANDS] = {
  70        /* SMB2_NEGOTIATE */ __constant_cpu_to_le16(65),
  71        /* SMB2_SESSION_SETUP */ __constant_cpu_to_le16(9),
  72        /* SMB2_LOGOFF */ __constant_cpu_to_le16(4),
  73        /* SMB2_TREE_CONNECT */ __constant_cpu_to_le16(16),
  74        /* SMB2_TREE_DISCONNECT */ __constant_cpu_to_le16(4),
  75        /* SMB2_CREATE */ __constant_cpu_to_le16(89),
  76        /* SMB2_CLOSE */ __constant_cpu_to_le16(60),
  77        /* SMB2_FLUSH */ __constant_cpu_to_le16(4),
  78        /* SMB2_READ */ __constant_cpu_to_le16(17),
  79        /* SMB2_WRITE */ __constant_cpu_to_le16(17),
  80        /* SMB2_LOCK */ __constant_cpu_to_le16(4),
  81        /* SMB2_IOCTL */ __constant_cpu_to_le16(49),
  82        /* BB CHECK this ... not listed in documentation */
  83        /* SMB2_CANCEL */ __constant_cpu_to_le16(0),
  84        /* SMB2_ECHO */ __constant_cpu_to_le16(4),
  85        /* SMB2_QUERY_DIRECTORY */ __constant_cpu_to_le16(9),
  86        /* SMB2_CHANGE_NOTIFY */ __constant_cpu_to_le16(9),
  87        /* SMB2_QUERY_INFO */ __constant_cpu_to_le16(9),
  88        /* SMB2_SET_INFO */ __constant_cpu_to_le16(2),
  89        /* BB FIXME can also be 44 for lease break */
  90        /* SMB2_OPLOCK_BREAK */ __constant_cpu_to_le16(24)
  91};
  92
  93int
  94smb2_check_message(char *buf, unsigned int length)
  95{
  96        struct smb2_hdr *hdr = (struct smb2_hdr *)buf;
  97        struct smb2_pdu *pdu = (struct smb2_pdu *)hdr;
  98        __u64 mid = hdr->MessageId;
  99        __u32 len = get_rfc1002_length(buf);
 100        __u32 clc_len;  /* calculated length */
 101        int command;
 102
 103        /* BB disable following printk later */
 104        cFYI(1, "%s length: 0x%x, smb_buf_length: 0x%x", __func__, length, len);
 105
 106        /*
 107         * Add function to do table lookup of StructureSize by command
 108         * ie Validate the wct via smb2_struct_sizes table above
 109         */
 110
 111        if (length < sizeof(struct smb2_pdu)) {
 112                if ((length >= sizeof(struct smb2_hdr)) && (hdr->Status != 0)) {
 113                        pdu->StructureSize2 = 0;
 114                        /*
 115                         * As with SMB/CIFS, on some error cases servers may
 116                         * not return wct properly
 117                         */
 118                        return 0;
 119                } else {
 120                        cERROR(1, "Length less than SMB header size");
 121                }
 122                return 1;
 123        }
 124        if (len > CIFSMaxBufSize + MAX_SMB2_HDR_SIZE - 4) {
 125                cERROR(1, "SMB length greater than maximum, mid=%llu", mid);
 126                return 1;
 127        }
 128
 129        if (check_smb2_hdr(hdr, mid))
 130                return 1;
 131
 132        if (hdr->StructureSize != SMB2_HEADER_STRUCTURE_SIZE) {
 133                cERROR(1, "Illegal structure size %u",
 134                          le16_to_cpu(hdr->StructureSize));
 135                return 1;
 136        }
 137
 138        command = le16_to_cpu(hdr->Command);
 139        if (command >= NUMBER_OF_SMB2_COMMANDS) {
 140                cERROR(1, "Illegal SMB2 command %d", command);
 141                return 1;
 142        }
 143
 144        if (smb2_rsp_struct_sizes[command] != pdu->StructureSize2) {
 145                if (hdr->Status == 0 ||
 146                    pdu->StructureSize2 != SMB2_ERROR_STRUCTURE_SIZE2) {
 147                        /* error packets have 9 byte structure size */
 148                        cERROR(1, "Illegal response size %u for command %d",
 149                                   le16_to_cpu(pdu->StructureSize2), command);
 150                        return 1;
 151                }
 152        }
 153
 154        if (4 + len != length) {
 155                cERROR(1, "Total length %u RFC1002 length %u mismatch mid %llu",
 156                          length, 4 + len, mid);
 157                return 1;
 158        }
 159
 160        clc_len = smb2_calc_size(hdr);
 161
 162        if (4 + len != clc_len) {
 163                cFYI(1, "Calculated size %u length %u mismatch mid %llu",
 164                        clc_len, 4 + len, mid);
 165                /* server can return one byte more */
 166                if (clc_len == 4 + len + 1)
 167                        return 0;
 168                return 1;
 169        }
 170        return 0;
 171}
 172
 173/*
 174 * The size of the variable area depends on the offset and length fields
 175 * located in different fields for various SMB2 responses. SMB2 responses
 176 * with no variable length info, show an offset of zero for the offset field.
 177 */
 178static const bool has_smb2_data_area[NUMBER_OF_SMB2_COMMANDS] = {
 179        /* SMB2_NEGOTIATE */ true,
 180        /* SMB2_SESSION_SETUP */ true,
 181        /* SMB2_LOGOFF */ false,
 182        /* SMB2_TREE_CONNECT */ false,
 183        /* SMB2_TREE_DISCONNECT */ false,
 184        /* SMB2_CREATE */ true,
 185        /* SMB2_CLOSE */ false,
 186        /* SMB2_FLUSH */ false,
 187        /* SMB2_READ */ true,
 188        /* SMB2_WRITE */ false,
 189        /* SMB2_LOCK */ false,
 190        /* SMB2_IOCTL */ true,
 191        /* SMB2_CANCEL */ false, /* BB CHECK this not listed in documentation */
 192        /* SMB2_ECHO */ false,
 193        /* SMB2_QUERY_DIRECTORY */ true,
 194        /* SMB2_CHANGE_NOTIFY */ true,
 195        /* SMB2_QUERY_INFO */ true,
 196        /* SMB2_SET_INFO */ false,
 197        /* SMB2_OPLOCK_BREAK */ false
 198};
 199
 200/*
 201 * Returns the pointer to the beginning of the data area. Length of the data
 202 * area and the offset to it (from the beginning of the smb are also returned.
 203 */
 204char *
 205smb2_get_data_area_len(int *off, int *len, struct smb2_hdr *hdr)
 206{
 207        *off = 0;
 208        *len = 0;
 209
 210        /* error responses do not have data area */
 211        if (hdr->Status && hdr->Status != STATUS_MORE_PROCESSING_REQUIRED &&
 212            (((struct smb2_err_rsp *)hdr)->StructureSize) ==
 213                                                SMB2_ERROR_STRUCTURE_SIZE2)
 214                return NULL;
 215
 216        /*
 217         * Following commands have data areas so we have to get the location
 218         * of the data buffer offset and data buffer length for the particular
 219         * command.
 220         */
 221        switch (hdr->Command) {
 222        case SMB2_NEGOTIATE:
 223                *off = le16_to_cpu(
 224                    ((struct smb2_negotiate_rsp *)hdr)->SecurityBufferOffset);
 225                *len = le16_to_cpu(
 226                    ((struct smb2_negotiate_rsp *)hdr)->SecurityBufferLength);
 227                break;
 228        case SMB2_SESSION_SETUP:
 229                *off = le16_to_cpu(
 230                    ((struct smb2_sess_setup_rsp *)hdr)->SecurityBufferOffset);
 231                *len = le16_to_cpu(
 232                    ((struct smb2_sess_setup_rsp *)hdr)->SecurityBufferLength);
 233                break;
 234        case SMB2_CREATE:
 235                *off = le32_to_cpu(
 236                    ((struct smb2_create_rsp *)hdr)->CreateContextsOffset);
 237                *len = le32_to_cpu(
 238                    ((struct smb2_create_rsp *)hdr)->CreateContextsLength);
 239                break;
 240        case SMB2_QUERY_INFO:
 241                *off = le16_to_cpu(
 242                    ((struct smb2_query_info_rsp *)hdr)->OutputBufferOffset);
 243                *len = le32_to_cpu(
 244                    ((struct smb2_query_info_rsp *)hdr)->OutputBufferLength);
 245                break;
 246        case SMB2_READ:
 247        case SMB2_QUERY_DIRECTORY:
 248        case SMB2_IOCTL:
 249        case SMB2_CHANGE_NOTIFY:
 250        default:
 251                /* BB FIXME for unimplemented cases above */
 252                cERROR(1, "no length check for command");
 253                break;
 254        }
 255
 256        /*
 257         * Invalid length or offset probably means data area is invalid, but
 258         * we have little choice but to ignore the data area in this case.
 259         */
 260        if (*off > 4096) {
 261                cERROR(1, "offset %d too large, data area ignored", *off);
 262                *len = 0;
 263                *off = 0;
 264        } else if (*off < 0) {
 265                cERROR(1, "negative offset %d to data invalid ignore data area",
 266                          *off);
 267                *off = 0;
 268                *len = 0;
 269        } else if (*len < 0) {
 270                cERROR(1, "negative data length %d invalid, data area ignored",
 271                          *len);
 272                *len = 0;
 273        } else if (*len > 128 * 1024) {
 274                cERROR(1, "data area larger than 128K: %d", *len);
 275                *len = 0;
 276        }
 277
 278        /* return pointer to beginning of data area, ie offset from SMB start */
 279        if ((*off != 0) && (*len != 0))
 280                return hdr->ProtocolId + *off;
 281        else
 282                return NULL;
 283}
 284
 285/*
 286 * Calculate the size of the SMB message based on the fixed header
 287 * portion, the number of word parameters and the data portion of the message.
 288 */
 289unsigned int
 290smb2_calc_size(struct smb2_hdr *hdr)
 291{
 292        struct smb2_pdu *pdu = (struct smb2_pdu *)hdr;
 293        int offset; /* the offset from the beginning of SMB to data area */
 294        int data_length; /* the length of the variable length data area */
 295        /* Structure Size has already been checked to make sure it is 64 */
 296        int len = 4 + le16_to_cpu(pdu->hdr.StructureSize);
 297
 298        /*
 299         * StructureSize2, ie length of fixed parameter area has already
 300         * been checked to make sure it is the correct length.
 301         */
 302        len += le16_to_cpu(pdu->StructureSize2);
 303
 304        if (has_smb2_data_area[le16_to_cpu(hdr->Command)] == false)
 305                goto calc_size_exit;
 306
 307        smb2_get_data_area_len(&offset, &data_length, hdr);
 308        cFYI(1, "SMB2 data length %d offset %d", data_length, offset);
 309
 310        if (data_length > 0) {
 311                /*
 312                 * Check to make sure that data area begins after fixed area,
 313                 * Note that last byte of the fixed area is part of data area
 314                 * for some commands, typically those with odd StructureSize,
 315                 * so we must add one to the calculation (and 4 to account for
 316                 * the size of the RFC1001 hdr.
 317                 */
 318                if (offset + 4 + 1 < len) {
 319                        cERROR(1, "data area offset %d overlaps SMB2 header %d",
 320                                  offset + 4 + 1, len);
 321                        data_length = 0;
 322                } else {
 323                        len = 4 + offset + data_length;
 324                }
 325        }
 326calc_size_exit:
 327        cFYI(1, "SMB2 len %d", len);
 328        return len;
 329}
 330
 331/* Note: caller must free return buffer */
 332__le16 *
 333cifs_convert_path_to_utf16(const char *from, struct cifs_sb_info *cifs_sb)
 334{
 335        int len;
 336        const char *start_of_path;
 337        __le16 *to;
 338
 339        /* Windows doesn't allow paths beginning with \ */
 340        if (from[0] == '\\')
 341                start_of_path = from + 1;
 342        else
 343                start_of_path = from;
 344        to = cifs_strndup_to_utf16(start_of_path, PATH_MAX, &len,
 345                                   cifs_sb->local_nls,
 346                                   cifs_sb->mnt_cifs_flags &
 347                                        CIFS_MOUNT_MAP_SPECIAL_CHR);
 348        return to;
 349}
 350
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