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");
  56         }
  57         cERROR(1, "Bad SMB detected. The Mid=%llu", hdr->MessageId);
  58         return 1;
  59 }
  60
  61 /*
  62  *  The following table defines the expected "StructureSize" of SMB2 responses
  63  *  in order by SMB2 command.  This is similar to "wct" in SMB/CIFS responses.
  64  *
  65  *  Note that commands are defined in smb2pdu.h in le16 but the array below is
  66  *  indexed by command in host byte order
  67  */
  68 static const __le16 smb2_rsp_struct_sizes[NUMBER_OF_SMB2_COMMANDS] = {
  69         /* SMB2_NEGOTIATE */ __constant_cpu_to_le16(65),
  70         /* SMB2_SESSION_SETUP */ __constant_cpu_to_le16(9),
  71         /* SMB2_LOGOFF */ __constant_cpu_to_le16(4),
  72         /* SMB2_TREE_CONNECT */ __constant_cpu_to_le16(16),
  73         /* SMB2_TREE_DISCONNECT */ __constant_cpu_to_le16(4),
  74         /* SMB2_CREATE */ __constant_cpu_to_le16(89),
  75         /* SMB2_CLOSE */ __constant_cpu_to_le16(60),
  76         /* SMB2_FLUSH */ __constant_cpu_to_le16(4),
  77         /* SMB2_READ */ __constant_cpu_to_le16(17),
  78         /* SMB2_WRITE */ __constant_cpu_to_le16(17),
  79         /* SMB2_LOCK */ __constant_cpu_to_le16(4),
  80         /* SMB2_IOCTL */ __constant_cpu_to_le16(49),
  81         /* BB CHECK this ... not listed in documentation */
  82         /* SMB2_CANCEL */ __constant_cpu_to_le16(0),
  83         /* SMB2_ECHO */ __constant_cpu_to_le16(4),
  84         /* SMB2_QUERY_DIRECTORY */ __constant_cpu_to_le16(9),
  85         /* SMB2_CHANGE_NOTIFY */ __constant_cpu_to_le16(9),
  86         /* SMB2_QUERY_INFO */ __constant_cpu_to_le16(9),
  87         /* SMB2_SET_INFO */ __constant_cpu_to_le16(2),
  88         /* BB FIXME can also be 44 for lease break */
  89         /* SMB2_OPLOCK_BREAK */ __constant_cpu_to_le16(24)
  90 };
  91
  92 int
  93 smb2_check_message(char *buf, unsigned int length)
  94 {
  95         struct smb2_hdr *hdr = (struct smb2_hdr *)buf;
  96         struct smb2_pdu *pdu = (struct smb2_pdu *)hdr;
  97         __u64 mid = hdr->MessageId;
  98         __u32 len = get_rfc1002_length(buf);
  99         __u32 clc_len;  /* calculated length */
 100         int command;
 101
 102         /* BB disable following printk later */
 103         cFYI(1, "%s length: 0x%x, smb_buf_length: 0x%x", __func__, length, len);
 104
 105         /*
 106          * Add function to do table lookup of StructureSize by command
 107          * ie Validate the wct via smb2_struct_sizes table above
 108          */
 109
 110         if (length < 2 + sizeof(struct smb2_hdr)) {
 111                 if ((length >= sizeof(struct smb2_hdr)) && (hdr->Status != 0)) {
 112                         pdu->StructureSize2 = 0;
 113                         /*
 114                          * As with SMB/CIFS, on some error cases servers may
 115                          * not return wct properly
 116                          */
 117                         return 0;
 118                 } else {
 119                         cERROR(1, "Length less than SMB header size");
 120                 }
 121                 return 1;
 122         }
 123         if (len > CIFSMaxBufSize + MAX_SMB2_HDR_SIZE - 4) {
 124                 cERROR(1, "SMB length greater than maximum, mid=%lld", mid);
 125                 return 1;
 126         }
 127
 128         if (check_smb2_hdr(hdr, mid))
 129                 return 1;
 130
 131         if (hdr->StructureSize != SMB2_HEADER_SIZE) {
 132                 cERROR(1, "Illegal structure size %d",
 133                           le16_to_cpu(hdr->StructureSize));
 134                 return 1;
 135         }
 136
 137         command = le16_to_cpu(hdr->Command);
 138         if (command >= NUMBER_OF_SMB2_COMMANDS) {
 139                 cERROR(1, "Illegal SMB2 command %d", command);
 140                 return 1;
 141         }
 142
 143         if (smb2_rsp_struct_sizes[command] != pdu->StructureSize2) {
 144                 if (hdr->Status == 0 ||
 145                     pdu->StructureSize2 != SMB2_ERROR_STRUCTURE_SIZE2) {
 146                         /* error packets have 9 byte structure size */
 147                         cERROR(1, "Illegal response size %u for command %d",
 148                                    le16_to_cpu(pdu->StructureSize2), command);
 149                         return 1;
 150                 }
 151         }
 152
 153         if (4 + len != length) {
 154                 cERROR(1, "Total length %u RFC1002 length %u mismatch mid %llu",
 155                           length, 4 + len, mid);
 156                 return 1;
 157         }
 158
 159         clc_len = smb2_calc_size(hdr);
 160
 161         if (4 + len != clc_len) {
 162                 cFYI(1, "Calculated size %u length %u mismatch mid %llu",
 163                         clc_len, 4 + len, mid);
 164                 if (clc_len == 4 + len + 1) /* BB FIXME (fix samba) */
 165                         return 0; /* BB workaround Samba 3 bug SessSetup rsp */
 166                 return 1;
 167         }
 168         return 0;
 169 }
 170
 171 /*
 172  * The size of the variable area depends on the offset and length fields
 173  * located in different fields for various SMB2 responses. SMB2 responses
 174  * with no variable length info, show an offset of zero for the offset field.
 175  */
 176 static const bool has_smb2_data_area[NUMBER_OF_SMB2_COMMANDS] = {
 177         /* SMB2_NEGOTIATE */ true,
 178         /* SMB2_SESSION_SETUP */ true,
 179         /* SMB2_LOGOFF */ false,
 180         /* SMB2_TREE_CONNECT */ false,
 181         /* SMB2_TREE_DISCONNECT */ false,
 182         /* SMB2_CREATE */ true,
 183         /* SMB2_CLOSE */ false,
 184         /* SMB2_FLUSH */ false,
 185         /* SMB2_READ */ true,
 186         /* SMB2_WRITE */ false,
 187         /* SMB2_LOCK */ false,
 188         /* SMB2_IOCTL */ true,
 189         /* SMB2_CANCEL */ false, /* BB CHECK this not listed in documentation */
 190         /* SMB2_ECHO */ false,
 191         /* SMB2_QUERY_DIRECTORY */ true,
 192         /* SMB2_CHANGE_NOTIFY */ true,
 193         /* SMB2_QUERY_INFO */ true,
 194         /* SMB2_SET_INFO */ false,
 195         /* SMB2_OPLOCK_BREAK */ false
 196 };
 197
 198 /*
 199  * Returns the pointer to the beginning of the data area. Length of the data
 200  * area and the offset to it (from the beginning of the smb are also returned.
 201  */
 202 char *
 203 smb2_get_data_area_len(int *off, int *len, struct smb2_hdr *hdr)
 204 {
 205         *off = 0;
 206         *len = 0;
 207
 208         /* error responses do not have data area */
 209         if (hdr->Status && hdr->Status != STATUS_MORE_PROCESSING_REQUIRED &&
 210             (((struct smb2_err_rsp *)hdr)->StructureSize) ==
 211                                                 SMB2_ERROR_STRUCTURE_SIZE2)
 212                 return NULL;
 213
 214         /*
 215          * Following commands have data areas so we have to get the location
 216          * of the data buffer offset and data buffer length for the particular
 217          * command.
 218          */
 219         switch (hdr->Command) {
 220         case SMB2_NEGOTIATE:
 221                 *off = le16_to_cpu(
 222                     ((struct smb2_negotiate_rsp *)hdr)->SecurityBufferOffset);
 223                 *len = le16_to_cpu(
 224                     ((struct smb2_negotiate_rsp *)hdr)->SecurityBufferLength);
 225                 break;
 226         case SMB2_SESSION_SETUP:
 227         case SMB2_CREATE:
 228         case SMB2_READ:
 229         case SMB2_QUERY_INFO:
 230         case SMB2_QUERY_DIRECTORY:
 231         case SMB2_IOCTL:
 232         case SMB2_CHANGE_NOTIFY:
 233         default:
 234                 /* BB FIXME for unimplemented cases above */
 235                 cERROR(1, "no length check for command");
 236                 break;
 237         }
 238
 239         /*
 240          * Invalid length or offset probably means data area is invalid, but
 241          * we have little choice but to ignore the data area in this case.
 242          */
 243         if (*off > 4096) {
 244                 cERROR(1, "offset %d too large, data area ignored", *off);
 245                 *len = 0;
 246                 *off = 0;
 247         } else if (*off < 0) {
 248                 cERROR(1, "negative offset %d to data invalid ignore data area",
 249                           *off);
 250                 *off = 0;
 251                 *len = 0;
 252         } else if (*len < 0) {
 253                 cERROR(1, "negative data length %d invalid, data area ignored",
 254                           *len);
 255                 *len = 0;
 256         } else if (*len > 128 * 1024) {
 257                 cERROR(1, "data area larger than 128K: %d", *len);
 258                 *len = 0;
 259         }
 260
 261         /* return pointer to beginning of data area, ie offset from SMB start */
 262         if ((*off != 0) && (*len != 0))
 263                 return hdr->ProtocolId + *off;
 264         else
 265                 return NULL;
 266 }
 267
 268 /*
 269  * Calculate the size of the SMB message based on the fixed header
 270  * portion, the number of word parameters and the data portion of the message.
 271  */
 272 unsigned int
 273 smb2_calc_size(struct smb2_hdr *hdr)
 274 {
 275         struct smb2_pdu *pdu = (struct smb2_pdu *)hdr;
 276         int offset; /* the offset from the beginning of SMB to data area */
 277         int data_length; /* the length of the variable length data area */
 278         /* Structure Size has already been checked to make sure it is 64 */
 279         int len = 4 + le16_to_cpu(pdu->hdr.StructureSize);
 280
 281         /*
 282          * StructureSize2, ie length of fixed parameter area has already
 283          * been checked to make sure it is the correct length.
 284          */
 285         len += le16_to_cpu(pdu->StructureSize2);
 286
 287         if (has_smb2_data_area[le16_to_cpu(hdr->Command)] == false)
 288                 goto calc_size_exit;
 289
 290         smb2_get_data_area_len(&offset, &data_length, hdr);
 291         cFYI(1, "SMB2 data length %d offset %d", data_length, offset);
 292
 293         if (data_length > 0) {
 294                 /*
 295                  * Check to make sure that data area begins after fixed area,
 296                  * Note that last byte of the fixed area is part of data area
 297                  * for some commands, typically those with odd StructureSize,
 298                  * so we must add one to the calculation (and 4 to account for
 299                  * the size of the RFC1001 hdr.
 300                  */
 301                 if (offset + 4 + 1 < len) {
 302                         cERROR(1, "data area offset %d overlaps SMB2 header %d",
 303                                   offset + 4 + 1, len);
 304                         data_length = 0;
 305                 } else {
 306                         len = 4 + offset + data_length;
 307                 }
 308         }
 309 calc_size_exit:
 310         cFYI(1, "SMB2 len %d", len);
 311         return len;
 312 }