fs/cifs/smb2misc.c

   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
  32 static int
  33 check_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  */
  69 static 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
  93 int
  94 smb2_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  */
 178 static 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  */
 204 char *
 205 smb2_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                 *off = ((struct smb2_read_rsp *)hdr)->DataOffset;
 248                 *len = le32_to_cpu(((struct smb2_read_rsp *)hdr)->DataLength);
 249                 break;
 250         case SMB2_QUERY_DIRECTORY:
 251         case SMB2_IOCTL:
 252         case SMB2_CHANGE_NOTIFY:
 253         default:
 254                 /* BB FIXME for unimplemented cases above */
 255                 cERROR(1, "no length check for command");
 256                 break;
 257         }
 258
 259         /*
 260          * Invalid length or offset probably means data area is invalid, but
 261          * we have little choice but to ignore the data area in this case.
 262          */
 263         if (*off > 4096) {
 264                 cERROR(1, "offset %d too large, data area ignored", *off);
 265                 *len = 0;
 266                 *off = 0;
 267         } else if (*off < 0) {
 268                 cERROR(1, "negative offset %d to data invalid ignore data area",
 269                           *off);
 270                 *off = 0;
 271                 *len = 0;
 272         } else if (*len < 0) {
 273                 cERROR(1, "negative data length %d invalid, data area ignored",
 274                           *len);
 275                 *len = 0;
 276         } else if (*len > 128 * 1024) {
 277                 cERROR(1, "data area larger than 128K: %d", *len);
 278                 *len = 0;
 279         }
 280
 281         /* return pointer to beginning of data area, ie offset from SMB start */
 282         if ((*off != 0) && (*len != 0))
 283                 return hdr->ProtocolId + *off;
 284         else
 285                 return NULL;
 286 }
 287
 288 /*
 289  * Calculate the size of the SMB message based on the fixed header
 290  * portion, the number of word parameters and the data portion of the message.
 291  */
 292 unsigned int
 293 smb2_calc_size(struct smb2_hdr *hdr)
 294 {
 295         struct smb2_pdu *pdu = (struct smb2_pdu *)hdr;
 296         int offset; /* the offset from the beginning of SMB to data area */
 297         int data_length; /* the length of the variable length data area */
 298         /* Structure Size has already been checked to make sure it is 64 */
 299         int len = 4 + le16_to_cpu(pdu->hdr.StructureSize);
 300
 301         /*
 302          * StructureSize2, ie length of fixed parameter area has already
 303          * been checked to make sure it is the correct length.
 304          */
 305         len += le16_to_cpu(pdu->StructureSize2);
 306
 307         if (has_smb2_data_area[le16_to_cpu(hdr->Command)] == false)
 308                 goto calc_size_exit;
 309
 310         smb2_get_data_area_len(&offset, &data_length, hdr);
 311         cFYI(1, "SMB2 data length %d offset %d", data_length, offset);
 312
 313         if (data_length > 0) {
 314                 /*
 315                  * Check to make sure that data area begins after fixed area,
 316                  * Note that last byte of the fixed area is part of data area
 317                  * for some commands, typically those with odd StructureSize,
 318                  * so we must add one to the calculation (and 4 to account for
 319                  * the size of the RFC1001 hdr.
 320                  */
 321                 if (offset + 4 + 1 < len) {
 322                         cERROR(1, "data area offset %d overlaps SMB2 header %d",
 323                                   offset + 4 + 1, len);
 324                         data_length = 0;
 325                 } else {
 326                         len = 4 + offset + data_length;
 327                 }
 328         }
 329 calc_size_exit:
 330         cFYI(1, "SMB2 len %d", len);
 331         return len;
 332 }
 333
 334 /* Note: caller must free return buffer */
 335 __le16 *
 336 cifs_convert_path_to_utf16(const char *from, struct cifs_sb_info *cifs_sb)
 337 {
 338         int len;
 339         const char *start_of_path;
 340         __le16 *to;
 341
 342         /* Windows doesn't allow paths beginning with \ */
 343         if (from[0] == '\\')
 344                 start_of_path = from + 1;
 345         else
 346                 start_of_path = from;
 347         to = cifs_strndup_to_utf16(start_of_path, PATH_MAX, &len,
 348                                    cifs_sb->local_nls,
 349                                    cifs_sb->mnt_cifs_flags &
 350                                         CIFS_MOUNT_MAP_SPECIAL_CHR);
 351         return to;
 352 }