kernel/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         __u64 wire_mid = le64_to_cpu(hdr->MessageId);
  36
  37         /*
  38          * Make sure that this really is an SMB, that it is a response,
  39          * and that the message ids match.
  40          */
  41         if ((*(__le32 *)hdr->ProtocolId == SMB2_PROTO_NUMBER) &&
  42             (mid == wire_mid)) {
  43                 if (hdr->Flags & SMB2_FLAGS_SERVER_TO_REDIR)
  44                         return 0;
  45                 else {
  46                         /* only one valid case where server sends us request */
  47                         if (hdr->Command == SMB2_OPLOCK_BREAK)
  48                                 return 0;
  49                         else
  50                                 cifs_dbg(VFS, "Received Request not response\n");
  51                 }
  52         } else { /* bad signature or mid */
  53                 if (*(__le32 *)hdr->ProtocolId != SMB2_PROTO_NUMBER)
  54                         cifs_dbg(VFS, "Bad protocol string signature header %x\n",
  55                                  *(unsigned int *) hdr->ProtocolId);
  56                 if (mid != wire_mid)
  57                         cifs_dbg(VFS, "Mids do not match: %llu and %llu\n",
  58                                  mid, wire_mid);
  59         }
  60         cifs_dbg(VFS, "Bad SMB detected. The Mid=%llu\n", wire_mid);
  61         return 1;
  62 }
  63
  64 /*
  65  *  The following table defines the expected "StructureSize" of SMB2 responses
  66  *  in order by SMB2 command.  This is similar to "wct" in SMB/CIFS responses.
  67  *
  68  *  Note that commands are defined in smb2pdu.h in le16 but the array below is
  69  *  indexed by command in host byte order
  70  */
  71 static const __le16 smb2_rsp_struct_sizes[NUMBER_OF_SMB2_COMMANDS] = {
  72         /* SMB2_NEGOTIATE */ cpu_to_le16(65),
  73         /* SMB2_SESSION_SETUP */ cpu_to_le16(9),
  74         /* SMB2_LOGOFF */ cpu_to_le16(4),
  75         /* SMB2_TREE_CONNECT */ cpu_to_le16(16),
  76         /* SMB2_TREE_DISCONNECT */ cpu_to_le16(4),
  77         /* SMB2_CREATE */ cpu_to_le16(89),
  78         /* SMB2_CLOSE */ cpu_to_le16(60),
  79         /* SMB2_FLUSH */ cpu_to_le16(4),
  80         /* SMB2_READ */ cpu_to_le16(17),
  81         /* SMB2_WRITE */ cpu_to_le16(17),
  82         /* SMB2_LOCK */ cpu_to_le16(4),
  83         /* SMB2_IOCTL */ cpu_to_le16(49),
  84         /* BB CHECK this ... not listed in documentation */
  85         /* SMB2_CANCEL */ cpu_to_le16(0),
  86         /* SMB2_ECHO */ cpu_to_le16(4),
  87         /* SMB2_QUERY_DIRECTORY */ cpu_to_le16(9),
  88         /* SMB2_CHANGE_NOTIFY */ cpu_to_le16(9),
  89         /* SMB2_QUERY_INFO */ cpu_to_le16(9),
  90         /* SMB2_SET_INFO */ cpu_to_le16(2),
  91         /* BB FIXME can also be 44 for lease break */
  92         /* SMB2_OPLOCK_BREAK */ cpu_to_le16(24)
  93 };
  94
  95 int
  96 smb2_check_message(char *buf, unsigned int length)
  97 {
  98         struct smb2_hdr *hdr = (struct smb2_hdr *)buf;
  99         struct smb2_pdu *pdu = (struct smb2_pdu *)hdr;
 100         __u64 mid = le64_to_cpu(hdr->MessageId);
 101         __u32 len = get_rfc1002_length(buf);
 102         __u32 clc_len;  /* calculated length */
 103         int command;
 104
 105         /* BB disable following printk later */
 106         cifs_dbg(FYI, "%s length: 0x%x, smb_buf_length: 0x%x\n",
 107                  __func__, length, len);
 108
 109         /*
 110          * Add function to do table lookup of StructureSize by command
 111          * ie Validate the wct via smb2_struct_sizes table above
 112          */
 113
 114         if (length < sizeof(struct smb2_pdu)) {
 115                 if ((length >= sizeof(struct smb2_hdr)) && (hdr->Status != 0)) {
 116                         pdu->StructureSize2 = 0;
 117                         /*
 118                          * As with SMB/CIFS, on some error cases servers may
 119                          * not return wct properly
 120                          */
 121                         return 0;
 122                 } else {
 123                         cifs_dbg(VFS, "Length less than SMB header size\n");
 124                 }
 125                 return 1;
 126         }
 127         if (len > CIFSMaxBufSize + MAX_SMB2_HDR_SIZE - 4) {
 128                 cifs_dbg(VFS, "SMB length greater than maximum, mid=%llu\n",
 129                          mid);
 130                 return 1;
 131         }
 132
 133         if (check_smb2_hdr(hdr, mid))
 134                 return 1;
 135
 136         if (hdr->StructureSize != SMB2_HEADER_STRUCTURE_SIZE) {
 137                 cifs_dbg(VFS, "Illegal structure size %u\n",
 138                          le16_to_cpu(hdr->StructureSize));
 139                 return 1;
 140         }
 141
 142         command = le16_to_cpu(hdr->Command);
 143         if (command >= NUMBER_OF_SMB2_COMMANDS) {
 144                 cifs_dbg(VFS, "Illegal SMB2 command %d\n", command);
 145                 return 1;
 146         }
 147
 148         if (smb2_rsp_struct_sizes[command] != pdu->StructureSize2) {
 149                 if (command != SMB2_OPLOCK_BREAK_HE && (hdr->Status == 0 ||
 150                     pdu->StructureSize2 != SMB2_ERROR_STRUCTURE_SIZE2)) {
 151                         /* error packets have 9 byte structure size */
 152                         cifs_dbg(VFS, "Illegal response size %u for command %d\n",
 153                                  le16_to_cpu(pdu->StructureSize2), command);
 154                         return 1;
 155                 } else if (command == SMB2_OPLOCK_BREAK_HE && (hdr->Status == 0)
 156                            && (le16_to_cpu(pdu->StructureSize2) != 44)
 157                            && (le16_to_cpu(pdu->StructureSize2) != 36)) {
 158                         /* special case for SMB2.1 lease break message */
 159                         cifs_dbg(VFS, "Illegal response size %d for oplock break\n",
 160                                  le16_to_cpu(pdu->StructureSize2));
 161                         return 1;
 162                 }
 163         }
 164
 165         if (4 + len != length) {
 166                 cifs_dbg(VFS, "Total length %u RFC1002 length %u mismatch mid %llu\n",
 167                          length, 4 + len, mid);
 168                 return 1;
 169         }
 170
 171         clc_len = smb2_calc_size(hdr);
 172
 173         if (4 + len != clc_len) {
 174                 cifs_dbg(FYI, "Calculated size %u length %u mismatch mid %llu\n",
 175                          clc_len, 4 + len, mid);
 176                 /* create failed on symlink */
 177                 if (command == SMB2_CREATE_HE &&
 178                     hdr->Status == STATUS_STOPPED_ON_SYMLINK)
 179                         return 0;
 180                 /* Windows 7 server returns 24 bytes more */
 181                 if (clc_len + 20 == len && command == SMB2_OPLOCK_BREAK_HE)
 182                         return 0;
 183                 /* server can return one byte more due to implied bcc[0] */
 184                 if (clc_len == 4 + len + 1)
 185                         return 0;
 186
 187                 /*
 188                  * MacOS server pads after SMB2.1 write response with 3 bytes
 189                  * of junk. Other servers match RFC1001 len to actual
 190                  * SMB2/SMB3 frame length (header + smb2 response specific data)
 191                  * Log the server error (once), but allow it and continue
 192                  * since the frame is parseable.
 193                  */
 194                 if (clc_len < 4 /* RFC1001 header size */ + len) {
 195                         printk_once(KERN_WARNING
 196                                 "SMB2 server sent bad RFC1001 len %d not %d\n",
 197                                 len, clc_len - 4);
 198                         return 0;
 199                 }
 200
 201                 return 1;
 202         }
 203         return 0;
 204 }
 205
 206 /*
 207  * The size of the variable area depends on the offset and length fields
 208  * located in different fields for various SMB2 responses. SMB2 responses
 209  * with no variable length info, show an offset of zero for the offset field.
 210  */
 211 static const bool has_smb2_data_area[NUMBER_OF_SMB2_COMMANDS] = {
 212         /* SMB2_NEGOTIATE */ true,
 213         /* SMB2_SESSION_SETUP */ true,
 214         /* SMB2_LOGOFF */ false,
 215         /* SMB2_TREE_CONNECT */ false,
 216         /* SMB2_TREE_DISCONNECT */ false,
 217         /* SMB2_CREATE */ true,
 218         /* SMB2_CLOSE */ false,
 219         /* SMB2_FLUSH */ false,
 220         /* SMB2_READ */ true,
 221         /* SMB2_WRITE */ false,
 222         /* SMB2_LOCK */ false,
 223         /* SMB2_IOCTL */ true,
 224         /* SMB2_CANCEL */ false, /* BB CHECK this not listed in documentation */
 225         /* SMB2_ECHO */ false,
 226         /* SMB2_QUERY_DIRECTORY */ true,
 227         /* SMB2_CHANGE_NOTIFY */ true,
 228         /* SMB2_QUERY_INFO */ true,
 229         /* SMB2_SET_INFO */ false,
 230         /* SMB2_OPLOCK_BREAK */ false
 231 };
 232
 233 /*
 234  * Returns the pointer to the beginning of the data area. Length of the data
 235  * area and the offset to it (from the beginning of the smb are also returned.
 236  */
 237 char *
 238 smb2_get_data_area_len(int *off, int *len, struct smb2_hdr *hdr)
 239 {
 240         *off = 0;
 241         *len = 0;
 242
 243         /* error responses do not have data area */
 244         if (hdr->Status && hdr->Status != STATUS_MORE_PROCESSING_REQUIRED &&
 245             (((struct smb2_err_rsp *)hdr)->StructureSize) ==
 246                                                 SMB2_ERROR_STRUCTURE_SIZE2)
 247                 return NULL;
 248
 249         /*
 250          * Following commands have data areas so we have to get the location
 251          * of the data buffer offset and data buffer length for the particular
 252          * command.
 253          */
 254         switch (hdr->Command) {
 255         case SMB2_NEGOTIATE:
 256                 *off = le16_to_cpu(
 257                     ((struct smb2_negotiate_rsp *)hdr)->SecurityBufferOffset);
 258                 *len = le16_to_cpu(
 259                     ((struct smb2_negotiate_rsp *)hdr)->SecurityBufferLength);
 260                 break;
 261         case SMB2_SESSION_SETUP:
 262                 *off = le16_to_cpu(
 263                     ((struct smb2_sess_setup_rsp *)hdr)->SecurityBufferOffset);
 264                 *len = le16_to_cpu(
 265                     ((struct smb2_sess_setup_rsp *)hdr)->SecurityBufferLength);
 266                 break;
 267         case SMB2_CREATE:
 268                 *off = le32_to_cpu(
 269                     ((struct smb2_create_rsp *)hdr)->CreateContextsOffset);
 270                 *len = le32_to_cpu(
 271                     ((struct smb2_create_rsp *)hdr)->CreateContextsLength);
 272                 break;
 273         case SMB2_QUERY_INFO:
 274                 *off = le16_to_cpu(
 275                     ((struct smb2_query_info_rsp *)hdr)->OutputBufferOffset);
 276                 *len = le32_to_cpu(
 277                     ((struct smb2_query_info_rsp *)hdr)->OutputBufferLength);
 278                 break;
 279         case SMB2_READ:
 280                 *off = ((struct smb2_read_rsp *)hdr)->DataOffset;
 281                 *len = le32_to_cpu(((struct smb2_read_rsp *)hdr)->DataLength);
 282                 break;
 283         case SMB2_QUERY_DIRECTORY:
 284                 *off = le16_to_cpu(
 285                   ((struct smb2_query_directory_rsp *)hdr)->OutputBufferOffset);
 286                 *len = le32_to_cpu(
 287                   ((struct smb2_query_directory_rsp *)hdr)->OutputBufferLength);
 288                 break;
 289         case SMB2_IOCTL:
 290                 *off = le32_to_cpu(
 291                   ((struct smb2_ioctl_rsp *)hdr)->OutputOffset);
 292                 *len = le32_to_cpu(((struct smb2_ioctl_rsp *)hdr)->OutputCount);
 293                 break;
 294         case SMB2_CHANGE_NOTIFY:
 295         default:
 296                 /* BB FIXME for unimplemented cases above */
 297                 cifs_dbg(VFS, "no length check for command\n");
 298                 break;
 299         }
 300
 301         /*
 302          * Invalid length or offset probably means data area is invalid, but
 303          * we have little choice but to ignore the data area in this case.
 304          */
 305         if (*off > 4096) {
 306                 cifs_dbg(VFS, "offset %d too large, data area ignored\n", *off);
 307                 *len = 0;
 308                 *off = 0;
 309         } else if (*off < 0) {
 310                 cifs_dbg(VFS, "negative offset %d to data invalid ignore data area\n",
 311                          *off);
 312                 *off = 0;
 313                 *len = 0;
 314         } else if (*len < 0) {
 315                 cifs_dbg(VFS, "negative data length %d invalid, data area ignored\n",
 316                          *len);
 317                 *len = 0;
 318         } else if (*len > 128 * 1024) {
 319                 cifs_dbg(VFS, "data area larger than 128K: %d\n", *len);
 320                 *len = 0;
 321         }
 322
 323         /* return pointer to beginning of data area, ie offset from SMB start */
 324         if ((*off != 0) && (*len != 0))
 325                 return (char *)(&hdr->ProtocolId[0]) + *off;
 326         else
 327                 return NULL;
 328 }
 329
 330 /*
 331  * Calculate the size of the SMB message based on the fixed header
 332  * portion, the number of word parameters and the data portion of the message.
 333  */
 334 unsigned int
 335 smb2_calc_size(void *buf)
 336 {
 337         struct smb2_hdr *hdr = (struct smb2_hdr *)buf;
 338         struct smb2_pdu *pdu = (struct smb2_pdu *)hdr;
 339         int offset; /* the offset from the beginning of SMB to data area */
 340         int data_length; /* the length of the variable length data area */
 341         /* Structure Size has already been checked to make sure it is 64 */
 342         int len = 4 + le16_to_cpu(pdu->hdr.StructureSize);
 343
 344         /*
 345          * StructureSize2, ie length of fixed parameter area has already
 346          * been checked to make sure it is the correct length.
 347          */
 348         len += le16_to_cpu(pdu->StructureSize2);
 349
 350         if (has_smb2_data_area[le16_to_cpu(hdr->Command)] == false)
 351                 goto calc_size_exit;
 352
 353         smb2_get_data_area_len(&offset, &data_length, hdr);
 354         cifs_dbg(FYI, "SMB2 data length %d offset %d\n", data_length, offset);
 355
 356         if (data_length > 0) {
 357                 /*
 358                  * Check to make sure that data area begins after fixed area,
 359                  * Note that last byte of the fixed area is part of data area
 360                  * for some commands, typically those with odd StructureSize,
 361                  * so we must add one to the calculation (and 4 to account for
 362                  * the size of the RFC1001 hdr.
 363                  */
 364                 if (offset + 4 + 1 < len) {
 365                         cifs_dbg(VFS, "data area offset %d overlaps SMB2 header %d\n",
 366                                  offset + 4 + 1, len);
 367                         data_length = 0;
 368                 } else {
 369                         len = 4 + offset + data_length;
 370                 }
 371         }
 372 calc_size_exit:
 373         cifs_dbg(FYI, "SMB2 len %d\n", len);
 374         return len;
 375 }
 376
 377 /* Note: caller must free return buffer */
 378 __le16 *
 379 cifs_convert_path_to_utf16(const char *from, struct cifs_sb_info *cifs_sb)
 380 {
 381         int len;
 382         const char *start_of_path;
 383         __le16 *to;
 384         int map_type;
 385
 386         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SFM_CHR)
 387                 map_type = SFM_MAP_UNI_RSVD;
 388         else if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR)
 389                 map_type = SFU_MAP_UNI_RSVD;
 390         else
 391                 map_type = NO_MAP_UNI_RSVD;
 392
 393         /* Windows doesn't allow paths beginning with \ */
 394         if (from[0] == '\\')
 395                 start_of_path = from + 1;
 396         else
 397                 start_of_path = from;
 398         to = cifs_strndup_to_utf16(start_of_path, PATH_MAX, &len,
 399                                    cifs_sb->local_nls, map_type);
 400         return to;
 401 }
 402
 403 __le32
 404 smb2_get_lease_state(struct cifsInodeInfo *cinode)
 405 {
 406         __le32 lease = 0;
 407
 408         if (CIFS_CACHE_WRITE(cinode))
 409                 lease |= SMB2_LEASE_WRITE_CACHING;
 410         if (CIFS_CACHE_HANDLE(cinode))
 411                 lease |= SMB2_LEASE_HANDLE_CACHING;
 412         if (CIFS_CACHE_READ(cinode))
 413                 lease |= SMB2_LEASE_READ_CACHING;
 414         return lease;
 415 }
 416
 417 struct smb2_lease_break_work {
 418         struct work_struct lease_break;
 419         struct tcon_link *tlink;
 420         __u8 lease_key[16];
 421         __le32 lease_state;
 422 };
 423
 424 static void
 425 cifs_ses_oplock_break(struct work_struct *work)
 426 {
 427         struct smb2_lease_break_work *lw = container_of(work,
 428                                 struct smb2_lease_break_work, lease_break);
 429         int rc;
 430
 431         rc = SMB2_lease_break(0, tlink_tcon(lw->tlink), lw->lease_key,
 432                               lw->lease_state);
 433         cifs_dbg(FYI, "Lease release rc %d\n", rc);
 434         cifs_put_tlink(lw->tlink);
 435         kfree(lw);
 436 }
 437
 438 static bool
 439 smb2_tcon_has_lease(struct cifs_tcon *tcon, struct smb2_lease_break *rsp,
 440                     struct smb2_lease_break_work *lw)
 441 {
 442         bool found;
 443         __u8 lease_state;
 444         struct list_head *tmp;
 445         struct cifsFileInfo *cfile;
 446         struct TCP_Server_Info *server = tcon->ses->server;
 447         struct cifs_pending_open *open;
 448         struct cifsInodeInfo *cinode;
 449         int ack_req = le32_to_cpu(rsp->Flags &
 450                                   SMB2_NOTIFY_BREAK_LEASE_FLAG_ACK_REQUIRED);
 451
 452         lease_state = le32_to_cpu(rsp->NewLeaseState);
 453
 454         list_for_each(tmp, &tcon->openFileList) {
 455                 cfile = list_entry(tmp, struct cifsFileInfo, tlist);
 456                 cinode = CIFS_I(d_inode(cfile->dentry));
 457
 458                 if (memcmp(cinode->lease_key, rsp->LeaseKey,
 459                                                         SMB2_LEASE_KEY_SIZE))
 460                         continue;
 461
 462                 cifs_dbg(FYI, "found in the open list\n");
 463                 cifs_dbg(FYI, "lease key match, lease break 0x%x\n",
 464                          le32_to_cpu(rsp->NewLeaseState));
 465
 466                 server->ops->set_oplock_level(cinode, lease_state, 0, NULL);
 467
 468                 if (ack_req)
 469                         cfile->oplock_break_cancelled = false;
 470                 else
 471                         cfile->oplock_break_cancelled = true;
 472
 473                 queue_work(cifsiod_wq, &cfile->oplock_break);
 474                 kfree(lw);
 475                 return true;
 476         }
 477
 478         found = false;
 479         list_for_each_entry(open, &tcon->pending_opens, olist) {
 480                 if (memcmp(open->lease_key, rsp->LeaseKey,
 481                            SMB2_LEASE_KEY_SIZE))
 482                         continue;
 483
 484                 if (!found && ack_req) {
 485                         found = true;
 486                         memcpy(lw->lease_key, open->lease_key,
 487                                SMB2_LEASE_KEY_SIZE);
 488                         lw->tlink = cifs_get_tlink(open->tlink);
 489                         queue_work(cifsiod_wq, &lw->lease_break);
 490                 }
 491
 492                 cifs_dbg(FYI, "found in the pending open list\n");
 493                 cifs_dbg(FYI, "lease key match, lease break 0x%x\n",
 494                          le32_to_cpu(rsp->NewLeaseState));
 495
 496                 open->oplock = lease_state;
 497         }
 498         return found;
 499 }
 500
 501 static bool
 502 smb2_is_valid_lease_break(char *buffer)
 503 {
 504         struct smb2_lease_break *rsp = (struct smb2_lease_break *)buffer;
 505         struct list_head *tmp, *tmp1, *tmp2;
 506         struct TCP_Server_Info *server;
 507         struct cifs_ses *ses;
 508         struct cifs_tcon *tcon;
 509         struct smb2_lease_break_work *lw;
 510
 511         lw = kmalloc(sizeof(struct smb2_lease_break_work), GFP_KERNEL);
 512         if (!lw)
 513                 return false;
 514
 515         INIT_WORK(&lw->lease_break, cifs_ses_oplock_break);
 516         lw->lease_state = rsp->NewLeaseState;
 517
 518         cifs_dbg(FYI, "Checking for lease break\n");
 519
 520         /* look up tcon based on tid & uid */
 521         spin_lock(&cifs_tcp_ses_lock);
 522         list_for_each(tmp, &cifs_tcp_ses_list) {
 523                 server = list_entry(tmp, struct TCP_Server_Info, tcp_ses_list);
 524
 525                 list_for_each(tmp1, &server->smb_ses_list) {
 526                         ses = list_entry(tmp1, struct cifs_ses, smb_ses_list);
 527
 528                         spin_lock(&cifs_file_list_lock);
 529                         list_for_each(tmp2, &ses->tcon_list) {
 530                                 tcon = list_entry(tmp2, struct cifs_tcon,
 531                                                   tcon_list);
 532                                 cifs_stats_inc(
 533                                     &tcon->stats.cifs_stats.num_oplock_brks);
 534                                 if (smb2_tcon_has_lease(tcon, rsp, lw)) {
 535                                         spin_unlock(&cifs_file_list_lock);
 536                                         spin_unlock(&cifs_tcp_ses_lock);
 537                                         return true;
 538                                 }
 539                         }
 540                         spin_unlock(&cifs_file_list_lock);
 541                 }
 542         }
 543         spin_unlock(&cifs_tcp_ses_lock);
 544         kfree(lw);
 545         cifs_dbg(FYI, "Can not process lease break - no lease matched\n");
 546         return false;
 547 }
 548
 549 bool
 550 smb2_is_valid_oplock_break(char *buffer, struct TCP_Server_Info *server)
 551 {
 552         struct smb2_oplock_break *rsp = (struct smb2_oplock_break *)buffer;
 553         struct list_head *tmp, *tmp1, *tmp2;
 554         struct cifs_ses *ses;
 555         struct cifs_tcon *tcon;
 556         struct cifsInodeInfo *cinode;
 557         struct cifsFileInfo *cfile;
 558
 559         cifs_dbg(FYI, "Checking for oplock break\n");
 560
 561         if (rsp->hdr.Command != SMB2_OPLOCK_BREAK)
 562                 return false;
 563
 564         if (rsp->StructureSize !=
 565                                 smb2_rsp_struct_sizes[SMB2_OPLOCK_BREAK_HE]) {
 566                 if (le16_to_cpu(rsp->StructureSize) == 44)
 567                         return smb2_is_valid_lease_break(buffer);
 568                 else
 569                         return false;
 570         }
 571
 572         cifs_dbg(FYI, "oplock level 0x%x\n", rsp->OplockLevel);
 573
 574         /* look up tcon based on tid & uid */
 575         spin_lock(&cifs_tcp_ses_lock);
 576         list_for_each(tmp, &server->smb_ses_list) {
 577                 ses = list_entry(tmp, struct cifs_ses, smb_ses_list);
 578                 list_for_each(tmp1, &ses->tcon_list) {
 579                         tcon = list_entry(tmp1, struct cifs_tcon, tcon_list);
 580
 581                         cifs_stats_inc(&tcon->stats.cifs_stats.num_oplock_brks);
 582                         spin_lock(&cifs_file_list_lock);
 583                         list_for_each(tmp2, &tcon->openFileList) {
 584                                 cfile = list_entry(tmp2, struct cifsFileInfo,
 585                                                      tlist);
 586                                 if (rsp->PersistentFid !=
 587                                     cfile->fid.persistent_fid ||
 588                                     rsp->VolatileFid !=
 589                                     cfile->fid.volatile_fid)
 590                                         continue;
 591
 592                                 cifs_dbg(FYI, "file id match, oplock break\n");
 593                                 cinode = CIFS_I(d_inode(cfile->dentry));
 594
 595                                 if (!CIFS_CACHE_WRITE(cinode) &&
 596                                     rsp->OplockLevel == SMB2_OPLOCK_LEVEL_NONE)
 597                                         cfile->oplock_break_cancelled = true;
 598                                 else
 599                                         cfile->oplock_break_cancelled = false;
 600
 601                                 set_bit(CIFS_INODE_PENDING_OPLOCK_BREAK,
 602                                         &cinode->flags);
 603
 604                                 /*
 605                                  * Set flag if the server downgrades the oplock
 606                                  * to L2 else clear.
 607                                  */
 608                                 if (rsp->OplockLevel)
 609                                         set_bit(
 610                                            CIFS_INODE_DOWNGRADE_OPLOCK_TO_L2,
 611                                            &cinode->flags);
 612                                 else
 613                                         clear_bit(
 614                                            CIFS_INODE_DOWNGRADE_OPLOCK_TO_L2,
 615                                            &cinode->flags);
 616
 617                                 queue_work(cifsiod_wq, &cfile->oplock_break);
 618
 619                                 spin_unlock(&cifs_file_list_lock);
 620                                 spin_unlock(&cifs_tcp_ses_lock);
 621                                 return true;
 622                         }
 623                         spin_unlock(&cifs_file_list_lock);
 624                         spin_unlock(&cifs_tcp_ses_lock);
 625                         cifs_dbg(FYI, "No matching file for oplock break\n");
 626                         return true;
 627                 }
 628         }
 629         spin_unlock(&cifs_tcp_ses_lock);
 630         cifs_dbg(FYI, "Can not process oplock break for non-existent connection\n");
 631         return false;
 632 }