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