fs/cifs/misc.c

   1 // SPDX-License-Identifier: LGPL-2.1
   2 /*
   3  *
   4  *   Copyright (C) International Business Machines  Corp., 2002,2008
   5  *   Author(s): Steve French ([email protected])
   6  *
   7  */
   8
   9 #include <linux/slab.h>
  10 #include <linux/ctype.h>
  11 #include <linux/mempool.h>
  12 #include <linux/vmalloc.h>
  13 #include "cifspdu.h"
  14 #include "cifsglob.h"
  15 #include "cifsproto.h"
  16 #include "cifs_debug.h"
  17 #include "smberr.h"
  18 #include "nterr.h"
  19 #include "cifs_unicode.h"
  20 #include "smb2pdu.h"
  21 #include "cifsfs.h"
  22 #ifdef CONFIG_CIFS_DFS_UPCALL
  23 #include "dns_resolve.h"
  24 #endif
  25 #include "fs_context.h"
  26
  27 extern mempool_t *cifs_sm_req_poolp;
  28 extern mempool_t *cifs_req_poolp;
  29
  30 /* The xid serves as a useful identifier for each incoming vfs request,
  31    in a similar way to the mid which is useful to track each sent smb,
  32    and CurrentXid can also provide a running counter (although it
  33    will eventually wrap past zero) of the total vfs operations handled
  34    since the cifs fs was mounted */
  35
  36 unsigned int
  37 _get_xid(void)
  38 {
  39         unsigned int xid;
  40
  41         spin_lock(&GlobalMid_Lock);
  42         GlobalTotalActiveXid++;
  43
  44         /* keep high water mark for number of simultaneous ops in filesystem */
  45         if (GlobalTotalActiveXid > GlobalMaxActiveXid)
  46                 GlobalMaxActiveXid = GlobalTotalActiveXid;
  47         if (GlobalTotalActiveXid > 65000)
  48                 cifs_dbg(FYI, "warning: more than 65000 requests active\n");
  49         xid = GlobalCurrentXid++;
  50         spin_unlock(&GlobalMid_Lock);
  51         return xid;
  52 }
  53
  54 void
  55 _free_xid(unsigned int xid)
  56 {
  57         spin_lock(&GlobalMid_Lock);
  58         /* if (GlobalTotalActiveXid == 0)
  59                 BUG(); */
  60         GlobalTotalActiveXid--;
  61         spin_unlock(&GlobalMid_Lock);
  62 }
  63
  64 struct cifs_ses *
  65 sesInfoAlloc(void)
  66 {
  67         struct cifs_ses *ret_buf;
  68
  69         ret_buf = kzalloc(sizeof(struct cifs_ses), GFP_KERNEL);
  70         if (ret_buf) {
  71                 atomic_inc(&sesInfoAllocCount);
  72                 ret_buf->status = CifsNew;
  73                 ++ret_buf->ses_count;
  74                 INIT_LIST_HEAD(&ret_buf->smb_ses_list);
  75                 INIT_LIST_HEAD(&ret_buf->tcon_list);
  76                 mutex_init(&ret_buf->session_mutex);
  77                 spin_lock_init(&ret_buf->iface_lock);
  78                 spin_lock_init(&ret_buf->chan_lock);
  79         }
  80         return ret_buf;
  81 }
  82
  83 void
  84 sesInfoFree(struct cifs_ses *buf_to_free)
  85 {
  86         if (buf_to_free == NULL) {
  87                 cifs_dbg(FYI, "Null buffer passed to sesInfoFree\n");
  88                 return;
  89         }
  90
  91         atomic_dec(&sesInfoAllocCount);
  92         kfree(buf_to_free->serverOS);
  93         kfree(buf_to_free->serverDomain);
  94         kfree(buf_to_free->serverNOS);
  95         kfree_sensitive(buf_to_free->password);
  96         kfree(buf_to_free->user_name);
  97         kfree(buf_to_free->domainName);
  98         kfree(buf_to_free->workstation_name);
  99         kfree_sensitive(buf_to_free->auth_key.response);
 100         kfree(buf_to_free->iface_list);
 101         kfree_sensitive(buf_to_free);
 102 }
 103
 104 struct cifs_tcon *
 105 tconInfoAlloc(void)
 106 {
 107         struct cifs_tcon *ret_buf;
 108
 109         ret_buf = kzalloc(sizeof(*ret_buf), GFP_KERNEL);
 110         if (!ret_buf)
 111                 return NULL;
 112         ret_buf->crfid.fid = kzalloc(sizeof(*ret_buf->crfid.fid), GFP_KERNEL);
 113         if (!ret_buf->crfid.fid) {
 114                 kfree(ret_buf);
 115                 return NULL;
 116         }
 117
 118         atomic_inc(&tconInfoAllocCount);
 119         ret_buf->status = TID_NEW;
 120         ++ret_buf->tc_count;
 121         INIT_LIST_HEAD(&ret_buf->openFileList);
 122         INIT_LIST_HEAD(&ret_buf->tcon_list);
 123         spin_lock_init(&ret_buf->open_file_lock);
 124         mutex_init(&ret_buf->crfid.fid_mutex);
 125         spin_lock_init(&ret_buf->stat_lock);
 126         atomic_set(&ret_buf->num_local_opens, 0);
 127         atomic_set(&ret_buf->num_remote_opens, 0);
 128
 129         return ret_buf;
 130 }
 131
 132 void
 133 tconInfoFree(struct cifs_tcon *buf_to_free)
 134 {
 135         if (buf_to_free == NULL) {
 136                 cifs_dbg(FYI, "Null buffer passed to tconInfoFree\n");
 137                 return;
 138         }
 139         atomic_dec(&tconInfoAllocCount);
 140         kfree(buf_to_free->nativeFileSystem);
 141         kfree_sensitive(buf_to_free->password);
 142         kfree(buf_to_free->crfid.fid);
 143         kfree(buf_to_free);
 144 }
 145
 146 struct smb_hdr *
 147 cifs_buf_get(void)
 148 {
 149         struct smb_hdr *ret_buf = NULL;
 150         /*
 151          * SMB2 header is bigger than CIFS one - no problems to clean some
 152          * more bytes for CIFS.
 153          */
 154         size_t buf_size = sizeof(struct smb2_hdr);
 155
 156         /*
 157          * We could use negotiated size instead of max_msgsize -
 158          * but it may be more efficient to always alloc same size
 159          * albeit slightly larger than necessary and maxbuffersize
 160          * defaults to this and can not be bigger.
 161          */
 162         ret_buf = mempool_alloc(cifs_req_poolp, GFP_NOFS);
 163
 164         /* clear the first few header bytes */
 165         /* for most paths, more is cleared in header_assemble */
 166         memset(ret_buf, 0, buf_size + 3);
 167         atomic_inc(&bufAllocCount);
 168 #ifdef CONFIG_CIFS_STATS2
 169         atomic_inc(&totBufAllocCount);
 170 #endif /* CONFIG_CIFS_STATS2 */
 171
 172         return ret_buf;
 173 }
 174
 175 void
 176 cifs_buf_release(void *buf_to_free)
 177 {
 178         if (buf_to_free == NULL) {
 179                 /* cifs_dbg(FYI, "Null buffer passed to cifs_buf_release\n");*/
 180                 return;
 181         }
 182         mempool_free(buf_to_free, cifs_req_poolp);
 183
 184         atomic_dec(&bufAllocCount);
 185         return;
 186 }
 187
 188 struct smb_hdr *
 189 cifs_small_buf_get(void)
 190 {
 191         struct smb_hdr *ret_buf = NULL;
 192
 193 /* We could use negotiated size instead of max_msgsize -
 194    but it may be more efficient to always alloc same size
 195    albeit slightly larger than necessary and maxbuffersize
 196    defaults to this and can not be bigger */
 197         ret_buf = mempool_alloc(cifs_sm_req_poolp, GFP_NOFS);
 198         /* No need to clear memory here, cleared in header assemble */
 199         /*      memset(ret_buf, 0, sizeof(struct smb_hdr) + 27);*/
 200         atomic_inc(&smBufAllocCount);
 201 #ifdef CONFIG_CIFS_STATS2
 202         atomic_inc(&totSmBufAllocCount);
 203 #endif /* CONFIG_CIFS_STATS2 */
 204
 205         return ret_buf;
 206 }
 207
 208 void
 209 cifs_small_buf_release(void *buf_to_free)
 210 {
 211
 212         if (buf_to_free == NULL) {
 213                 cifs_dbg(FYI, "Null buffer passed to cifs_small_buf_release\n");
 214                 return;
 215         }
 216         mempool_free(buf_to_free, cifs_sm_req_poolp);
 217
 218         atomic_dec(&smBufAllocCount);
 219         return;
 220 }
 221
 222 void
 223 free_rsp_buf(int resp_buftype, void *rsp)
 224 {
 225         if (resp_buftype == CIFS_SMALL_BUFFER)
 226                 cifs_small_buf_release(rsp);
 227         else if (resp_buftype == CIFS_LARGE_BUFFER)
 228                 cifs_buf_release(rsp);
 229 }
 230
 231 /* NB: MID can not be set if treeCon not passed in, in that
 232    case it is responsbility of caller to set the mid */
 233 void
 234 header_assemble(struct smb_hdr *buffer, char smb_command /* command */ ,
 235                 const struct cifs_tcon *treeCon, int word_count
 236                 /* length of fixed section (word count) in two byte units  */)
 237 {
 238         char *temp = (char *) buffer;
 239
 240         memset(temp, 0, 256); /* bigger than MAX_CIFS_HDR_SIZE */
 241
 242         buffer->smb_buf_length = cpu_to_be32(
 243             (2 * word_count) + sizeof(struct smb_hdr) -
 244             4 /*  RFC 1001 length field does not count */  +
 245             2 /* for bcc field itself */) ;
 246
 247         buffer->Protocol[0] = 0xFF;
 248         buffer->Protocol[1] = 'S';
 249         buffer->Protocol[2] = 'M';
 250         buffer->Protocol[3] = 'B';
 251         buffer->Command = smb_command;
 252         buffer->Flags = 0x00;   /* case sensitive */
 253         buffer->Flags2 = SMBFLG2_KNOWS_LONG_NAMES;
 254         buffer->Pid = cpu_to_le16((__u16)current->tgid);
 255         buffer->PidHigh = cpu_to_le16((__u16)(current->tgid >> 16));
 256         if (treeCon) {
 257                 buffer->Tid = treeCon->tid;
 258                 if (treeCon->ses) {
 259                         if (treeCon->ses->capabilities & CAP_UNICODE)
 260                                 buffer->Flags2 |= SMBFLG2_UNICODE;
 261                         if (treeCon->ses->capabilities & CAP_STATUS32)
 262                                 buffer->Flags2 |= SMBFLG2_ERR_STATUS;
 263
 264                         /* Uid is not converted */
 265                         buffer->Uid = treeCon->ses->Suid;
 266                         if (treeCon->ses->server)
 267                                 buffer->Mid = get_next_mid(treeCon->ses->server);
 268                 }
 269                 if (treeCon->Flags & SMB_SHARE_IS_IN_DFS)
 270                         buffer->Flags2 |= SMBFLG2_DFS;
 271                 if (treeCon->nocase)
 272                         buffer->Flags  |= SMBFLG_CASELESS;
 273                 if ((treeCon->ses) && (treeCon->ses->server))
 274                         if (treeCon->ses->server->sign)
 275                                 buffer->Flags2 |= SMBFLG2_SECURITY_SIGNATURE;
 276         }
 277
 278 /*  endian conversion of flags is now done just before sending */
 279         buffer->WordCount = (char) word_count;
 280         return;
 281 }
 282
 283 static int
 284 check_smb_hdr(struct smb_hdr *smb)
 285 {
 286         /* does it have the right SMB "signature" ? */
 287         if (*(__le32 *) smb->Protocol != cpu_to_le32(0x424d53ff)) {
 288                 cifs_dbg(VFS, "Bad protocol string signature header 0x%x\n",
 289                          *(unsigned int *)smb->Protocol);
 290                 return 1;
 291         }
 292
 293         /* if it's a response then accept */
 294         if (smb->Flags & SMBFLG_RESPONSE)
 295                 return 0;
 296
 297         /* only one valid case where server sends us request */
 298         if (smb->Command == SMB_COM_LOCKING_ANDX)
 299                 return 0;
 300
 301         cifs_dbg(VFS, "Server sent request, not response. mid=%u\n",
 302                  get_mid(smb));
 303         return 1;
 304 }
 305
 306 int
 307 checkSMB(char *buf, unsigned int total_read, struct TCP_Server_Info *server)
 308 {
 309         struct smb_hdr *smb = (struct smb_hdr *)buf;
 310         __u32 rfclen = be32_to_cpu(smb->smb_buf_length);
 311         __u32 clc_len;  /* calculated length */
 312         cifs_dbg(FYI, "checkSMB Length: 0x%x, smb_buf_length: 0x%x\n",
 313                  total_read, rfclen);
 314
 315         /* is this frame too small to even get to a BCC? */
 316         if (total_read < 2 + sizeof(struct smb_hdr)) {
 317                 if ((total_read >= sizeof(struct smb_hdr) - 1)
 318                             && (smb->Status.CifsError != 0)) {
 319                         /* it's an error return */
 320                         smb->WordCount = 0;
 321                         /* some error cases do not return wct and bcc */
 322                         return 0;
 323                 } else if ((total_read == sizeof(struct smb_hdr) + 1) &&
 324                                 (smb->WordCount == 0)) {
 325                         char *tmp = (char *)smb;
 326                         /* Need to work around a bug in two servers here */
 327                         /* First, check if the part of bcc they sent was zero */
 328                         if (tmp[sizeof(struct smb_hdr)] == 0) {
 329                                 /* some servers return only half of bcc
 330                                  * on simple responses (wct, bcc both zero)
 331                                  * in particular have seen this on
 332                                  * ulogoffX and FindClose. This leaves
 333                                  * one byte of bcc potentially unitialized
 334                                  */
 335                                 /* zero rest of bcc */
 336                                 tmp[sizeof(struct smb_hdr)+1] = 0;
 337                                 return 0;
 338                         }
 339                         cifs_dbg(VFS, "rcvd invalid byte count (bcc)\n");
 340                 } else {
 341                         cifs_dbg(VFS, "Length less than smb header size\n");
 342                 }
 343                 return -EIO;
 344         }
 345
 346         /* otherwise, there is enough to get to the BCC */
 347         if (check_smb_hdr(smb))
 348                 return -EIO;
 349         clc_len = smbCalcSize(smb, server);
 350
 351         if (4 + rfclen != total_read) {
 352                 cifs_dbg(VFS, "Length read does not match RFC1001 length %d\n",
 353                          rfclen);
 354                 return -EIO;
 355         }
 356
 357         if (4 + rfclen != clc_len) {
 358                 __u16 mid = get_mid(smb);
 359                 /* check if bcc wrapped around for large read responses */
 360                 if ((rfclen > 64 * 1024) && (rfclen > clc_len)) {
 361                         /* check if lengths match mod 64K */
 362                         if (((4 + rfclen) & 0xFFFF) == (clc_len & 0xFFFF))
 363                                 return 0; /* bcc wrapped */
 364                 }
 365                 cifs_dbg(FYI, "Calculated size %u vs length %u mismatch for mid=%u\n",
 366                          clc_len, 4 + rfclen, mid);
 367
 368                 if (4 + rfclen < clc_len) {
 369                         cifs_dbg(VFS, "RFC1001 size %u smaller than SMB for mid=%u\n",
 370                                  rfclen, mid);
 371                         return -EIO;
 372                 } else if (rfclen > clc_len + 512) {
 373                         /*
 374                          * Some servers (Windows XP in particular) send more
 375                          * data than the lengths in the SMB packet would
 376                          * indicate on certain calls (byte range locks and
 377                          * trans2 find first calls in particular). While the
 378                          * client can handle such a frame by ignoring the
 379                          * trailing data, we choose limit the amount of extra
 380                          * data to 512 bytes.
 381                          */
 382                         cifs_dbg(VFS, "RFC1001 size %u more than 512 bytes larger than SMB for mid=%u\n",
 383                                  rfclen, mid);
 384                         return -EIO;
 385                 }
 386         }
 387         return 0;
 388 }
 389
 390 bool
 391 is_valid_oplock_break(char *buffer, struct TCP_Server_Info *srv)
 392 {
 393         struct smb_hdr *buf = (struct smb_hdr *)buffer;
 394         struct smb_com_lock_req *pSMB = (struct smb_com_lock_req *)buf;
 395         struct list_head *tmp, *tmp1, *tmp2;
 396         struct cifs_ses *ses;
 397         struct cifs_tcon *tcon;
 398         struct cifsInodeInfo *pCifsInode;
 399         struct cifsFileInfo *netfile;
 400
 401         cifs_dbg(FYI, "Checking for oplock break or dnotify response\n");
 402         if ((pSMB->hdr.Command == SMB_COM_NT_TRANSACT) &&
 403            (pSMB->hdr.Flags & SMBFLG_RESPONSE)) {
 404                 struct smb_com_transaction_change_notify_rsp *pSMBr =
 405                         (struct smb_com_transaction_change_notify_rsp *)buf;
 406                 struct file_notify_information *pnotify;
 407                 __u32 data_offset = 0;
 408                 size_t len = srv->total_read - sizeof(pSMBr->hdr.smb_buf_length);
 409
 410                 if (get_bcc(buf) > sizeof(struct file_notify_information)) {
 411                         data_offset = le32_to_cpu(pSMBr->DataOffset);
 412
 413                         if (data_offset >
 414                             len - sizeof(struct file_notify_information)) {
 415                                 cifs_dbg(FYI, "Invalid data_offset %u\n",
 416                                          data_offset);
 417                                 return true;
 418                         }
 419                         pnotify = (struct file_notify_information *)
 420                                 ((char *)&pSMBr->hdr.Protocol + data_offset);
 421                         cifs_dbg(FYI, "dnotify on %s Action: 0x%x\n",
 422                                  pnotify->FileName, pnotify->Action);
 423                         /*   cifs_dump_mem("Rcvd notify Data: ",buf,
 424                                 sizeof(struct smb_hdr)+60); */
 425                         return true;
 426                 }
 427                 if (pSMBr->hdr.Status.CifsError) {
 428                         cifs_dbg(FYI, "notify err 0x%x\n",
 429                                  pSMBr->hdr.Status.CifsError);
 430                         return true;
 431                 }
 432                 return false;
 433         }
 434         if (pSMB->hdr.Command != SMB_COM_LOCKING_ANDX)
 435                 return false;
 436         if (pSMB->hdr.Flags & SMBFLG_RESPONSE) {
 437                 /* no sense logging error on invalid handle on oplock
 438                    break - harmless race between close request and oplock
 439                    break response is expected from time to time writing out
 440                    large dirty files cached on the client */
 441                 if ((NT_STATUS_INVALID_HANDLE) ==
 442                    le32_to_cpu(pSMB->hdr.Status.CifsError)) {
 443                         cifs_dbg(FYI, "Invalid handle on oplock break\n");
 444                         return true;
 445                 } else if (ERRbadfid ==
 446                    le16_to_cpu(pSMB->hdr.Status.DosError.Error)) {
 447                         return true;
 448                 } else {
 449                         return false; /* on valid oplock brk we get "request" */
 450                 }
 451         }
 452         if (pSMB->hdr.WordCount != 8)
 453                 return false;
 454
 455         cifs_dbg(FYI, "oplock type 0x%x level 0x%x\n",
 456                  pSMB->LockType, pSMB->OplockLevel);
 457         if (!(pSMB->LockType & LOCKING_ANDX_OPLOCK_RELEASE))
 458                 return false;
 459
 460         /* look up tcon based on tid & uid */
 461         spin_lock(&cifs_tcp_ses_lock);
 462         list_for_each(tmp, &srv->smb_ses_list) {
 463                 ses = list_entry(tmp, struct cifs_ses, smb_ses_list);
 464                 list_for_each(tmp1, &ses->tcon_list) {
 465                         tcon = list_entry(tmp1, struct cifs_tcon, tcon_list);
 466                         if (tcon->tid != buf->Tid)
 467                                 continue;
 468
 469                         cifs_stats_inc(&tcon->stats.cifs_stats.num_oplock_brks);
 470                         spin_lock(&tcon->open_file_lock);
 471                         list_for_each(tmp2, &tcon->openFileList) {
 472                                 netfile = list_entry(tmp2, struct cifsFileInfo,
 473                                                      tlist);
 474                                 if (pSMB->Fid != netfile->fid.netfid)
 475                                         continue;
 476
 477                                 cifs_dbg(FYI, "file id match, oplock break\n");
 478                                 pCifsInode = CIFS_I(d_inode(netfile->dentry));
 479
 480                                 set_bit(CIFS_INODE_PENDING_OPLOCK_BREAK,
 481                                         &pCifsInode->flags);
 482
 483                                 netfile->oplock_epoch = 0;
 484                                 netfile->oplock_level = pSMB->OplockLevel;
 485                                 netfile->oplock_break_cancelled = false;
 486                                 cifs_queue_oplock_break(netfile);
 487
 488                                 spin_unlock(&tcon->open_file_lock);
 489                                 spin_unlock(&cifs_tcp_ses_lock);
 490                                 return true;
 491                         }
 492                         spin_unlock(&tcon->open_file_lock);
 493                         spin_unlock(&cifs_tcp_ses_lock);
 494                         cifs_dbg(FYI, "No matching file for oplock break\n");
 495                         return true;
 496                 }
 497         }
 498         spin_unlock(&cifs_tcp_ses_lock);
 499         cifs_dbg(FYI, "Can not process oplock break for non-existent connection\n");
 500         return true;
 501 }
 502
 503 void
 504 dump_smb(void *buf, int smb_buf_length)
 505 {
 506         if (traceSMB == 0)
 507                 return;
 508
 509         print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_NONE, 8, 2, buf,
 510                        smb_buf_length, true);
 511 }
 512
 513 void
 514 cifs_autodisable_serverino(struct cifs_sb_info *cifs_sb)
 515 {
 516         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SERVER_INUM) {
 517                 struct cifs_tcon *tcon = NULL;
 518
 519                 if (cifs_sb->master_tlink)
 520                         tcon = cifs_sb_master_tcon(cifs_sb);
 521
 522                 cifs_sb->mnt_cifs_flags &= ~CIFS_MOUNT_SERVER_INUM;
 523                 cifs_sb->mnt_cifs_serverino_autodisabled = true;
 524                 cifs_dbg(VFS, "Autodisabling the use of server inode numbers on %s\n",
 525                          tcon ? tcon->treeName : "new server");
 526                 cifs_dbg(VFS, "The server doesn't seem to support them properly or the files might be on different servers (DFS)\n");
 527                 cifs_dbg(VFS, "Hardlinks will not be recognized on this mount. Consider mounting with the \"noserverino\" option to silence this message.\n");
 528
 529         }
 530 }
 531
 532 void cifs_set_oplock_level(struct cifsInodeInfo *cinode, __u32 oplock)
 533 {
 534         oplock &= 0xF;
 535
 536         if (oplock == OPLOCK_EXCLUSIVE) {
 537                 cinode->oplock = CIFS_CACHE_WRITE_FLG | CIFS_CACHE_READ_FLG;
 538                 cifs_dbg(FYI, "Exclusive Oplock granted on inode %p\n",
 539                          &cinode->vfs_inode);
 540         } else if (oplock == OPLOCK_READ) {
 541                 cinode->oplock = CIFS_CACHE_READ_FLG;
 542                 cifs_dbg(FYI, "Level II Oplock granted on inode %p\n",
 543                          &cinode->vfs_inode);
 544         } else
 545                 cinode->oplock = 0;
 546 }
 547
 548 /*
 549  * We wait for oplock breaks to be processed before we attempt to perform
 550  * writes.
 551  */
 552 int cifs_get_writer(struct cifsInodeInfo *cinode)
 553 {
 554         int rc;
 555
 556 start:
 557         rc = wait_on_bit(&cinode->flags, CIFS_INODE_PENDING_OPLOCK_BREAK,
 558                          TASK_KILLABLE);
 559         if (rc)
 560                 return rc;
 561
 562         spin_lock(&cinode->writers_lock);
 563         if (!cinode->writers)
 564                 set_bit(CIFS_INODE_PENDING_WRITERS, &cinode->flags);
 565         cinode->writers++;
 566         /* Check to see if we have started servicing an oplock break */
 567         if (test_bit(CIFS_INODE_PENDING_OPLOCK_BREAK, &cinode->flags)) {
 568                 cinode->writers--;
 569                 if (cinode->writers == 0) {
 570                         clear_bit(CIFS_INODE_PENDING_WRITERS, &cinode->flags);
 571                         wake_up_bit(&cinode->flags, CIFS_INODE_PENDING_WRITERS);
 572                 }
 573                 spin_unlock(&cinode->writers_lock);
 574                 goto start;
 575         }
 576         spin_unlock(&cinode->writers_lock);
 577         return 0;
 578 }
 579
 580 void cifs_put_writer(struct cifsInodeInfo *cinode)
 581 {
 582         spin_lock(&cinode->writers_lock);
 583         cinode->writers--;
 584         if (cinode->writers == 0) {
 585                 clear_bit(CIFS_INODE_PENDING_WRITERS, &cinode->flags);
 586                 wake_up_bit(&cinode->flags, CIFS_INODE_PENDING_WRITERS);
 587         }
 588         spin_unlock(&cinode->writers_lock);
 589 }
 590
 591 /**
 592  * cifs_queue_oplock_break - queue the oplock break handler for cfile
 593  * @cfile: The file to break the oplock on
 594  *
 595  * This function is called from the demultiplex thread when it
 596  * receives an oplock break for @cfile.
 597  *
 598  * Assumes the tcon->open_file_lock is held.
 599  * Assumes cfile->file_info_lock is NOT held.
 600  */
 601 void cifs_queue_oplock_break(struct cifsFileInfo *cfile)
 602 {
 603         /*
 604          * Bump the handle refcount now while we hold the
 605          * open_file_lock to enforce the validity of it for the oplock
 606          * break handler. The matching put is done at the end of the
 607          * handler.
 608          */
 609         cifsFileInfo_get(cfile);
 610
 611         queue_work(cifsoplockd_wq, &cfile->oplock_break);
 612 }
 613
 614 void cifs_done_oplock_break(struct cifsInodeInfo *cinode)
 615 {
 616         clear_bit(CIFS_INODE_PENDING_OPLOCK_BREAK, &cinode->flags);
 617         wake_up_bit(&cinode->flags, CIFS_INODE_PENDING_OPLOCK_BREAK);
 618 }
 619
 620 bool
 621 backup_cred(struct cifs_sb_info *cifs_sb)
 622 {
 623         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_BACKUPUID) {
 624                 if (uid_eq(cifs_sb->ctx->backupuid, current_fsuid()))
 625                         return true;
 626         }
 627         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_BACKUPGID) {
 628                 if (in_group_p(cifs_sb->ctx->backupgid))
 629                         return true;
 630         }
 631
 632         return false;
 633 }
 634
 635 void
 636 cifs_del_pending_open(struct cifs_pending_open *open)
 637 {
 638         spin_lock(&tlink_tcon(open->tlink)->open_file_lock);
 639         list_del(&open->olist);
 640         spin_unlock(&tlink_tcon(open->tlink)->open_file_lock);
 641 }
 642
 643 void
 644 cifs_add_pending_open_locked(struct cifs_fid *fid, struct tcon_link *tlink,
 645                              struct cifs_pending_open *open)
 646 {
 647         memcpy(open->lease_key, fid->lease_key, SMB2_LEASE_KEY_SIZE);
 648         open->oplock = CIFS_OPLOCK_NO_CHANGE;
 649         open->tlink = tlink;
 650         fid->pending_open = open;
 651         list_add_tail(&open->olist, &tlink_tcon(tlink)->pending_opens);
 652 }
 653
 654 void
 655 cifs_add_pending_open(struct cifs_fid *fid, struct tcon_link *tlink,
 656                       struct cifs_pending_open *open)
 657 {
 658         spin_lock(&tlink_tcon(tlink)->open_file_lock);
 659         cifs_add_pending_open_locked(fid, tlink, open);
 660         spin_unlock(&tlink_tcon(open->tlink)->open_file_lock);
 661 }
 662
 663 /*
 664  * Critical section which runs after acquiring deferred_lock.
 665  * As there is no reference count on cifs_deferred_close, pdclose
 666  * should not be used outside deferred_lock.
 667  */
 668 bool
 669 cifs_is_deferred_close(struct cifsFileInfo *cfile, struct cifs_deferred_close **pdclose)
 670 {
 671         struct cifs_deferred_close *dclose;
 672
 673         list_for_each_entry(dclose, &CIFS_I(d_inode(cfile->dentry))->deferred_closes, dlist) {
 674                 if ((dclose->netfid == cfile->fid.netfid) &&
 675                         (dclose->persistent_fid == cfile->fid.persistent_fid) &&
 676                         (dclose->volatile_fid == cfile->fid.volatile_fid)) {
 677                         *pdclose = dclose;
 678                         return true;
 679                 }
 680         }
 681         return false;
 682 }
 683
 684 /*
 685  * Critical section which runs after acquiring deferred_lock.
 686  */
 687 void
 688 cifs_add_deferred_close(struct cifsFileInfo *cfile, struct cifs_deferred_close *dclose)
 689 {
 690         bool is_deferred = false;
 691         struct cifs_deferred_close *pdclose;
 692
 693         is_deferred = cifs_is_deferred_close(cfile, &pdclose);
 694         if (is_deferred) {
 695                 kfree(dclose);
 696                 return;
 697         }
 698
 699         dclose->tlink = cfile->tlink;
 700         dclose->netfid = cfile->fid.netfid;
 701         dclose->persistent_fid = cfile->fid.persistent_fid;
 702         dclose->volatile_fid = cfile->fid.volatile_fid;
 703         list_add_tail(&dclose->dlist, &CIFS_I(d_inode(cfile->dentry))->deferred_closes);
 704 }
 705
 706 /*
 707  * Critical section which runs after acquiring deferred_lock.
 708  */
 709 void
 710 cifs_del_deferred_close(struct cifsFileInfo *cfile)
 711 {
 712         bool is_deferred = false;
 713         struct cifs_deferred_close *dclose;
 714
 715         is_deferred = cifs_is_deferred_close(cfile, &dclose);
 716         if (!is_deferred)
 717                 return;
 718         list_del(&dclose->dlist);
 719         kfree(dclose);
 720 }
 721
 722 void
 723 cifs_close_deferred_file(struct cifsInodeInfo *cifs_inode)
 724 {
 725         struct cifsFileInfo *cfile = NULL;
 726         struct file_list *tmp_list, *tmp_next_list;
 727         struct list_head file_head;
 728
 729         if (cifs_inode == NULL)
 730                 return;
 731
 732         INIT_LIST_HEAD(&file_head);
 733         spin_lock(&cifs_inode->open_file_lock);
 734         list_for_each_entry(cfile, &cifs_inode->openFileList, flist) {
 735                 if (delayed_work_pending(&cfile->deferred)) {
 736                         if (cancel_delayed_work(&cfile->deferred)) {
 737                                 tmp_list = kmalloc(sizeof(struct file_list), GFP_ATOMIC);
 738                                 if (tmp_list == NULL)
 739                                         break;
 740                                 tmp_list->cfile = cfile;
 741                                 list_add_tail(&tmp_list->list, &file_head);
 742                         }
 743                 }
 744         }
 745         spin_unlock(&cifs_inode->open_file_lock);
 746
 747         list_for_each_entry_safe(tmp_list, tmp_next_list, &file_head, list) {
 748                 _cifsFileInfo_put(tmp_list->cfile, true, false);
 749                 list_del(&tmp_list->list);
 750                 kfree(tmp_list);
 751         }
 752 }
 753
 754 void
 755 cifs_close_all_deferred_files(struct cifs_tcon *tcon)
 756 {
 757         struct cifsFileInfo *cfile;
 758         struct list_head *tmp;
 759         struct file_list *tmp_list, *tmp_next_list;
 760         struct list_head file_head;
 761
 762         INIT_LIST_HEAD(&file_head);
 763         spin_lock(&tcon->open_file_lock);
 764         list_for_each(tmp, &tcon->openFileList) {
 765                 cfile = list_entry(tmp, struct cifsFileInfo, tlist);
 766                 if (delayed_work_pending(&cfile->deferred)) {
 767                         if (cancel_delayed_work(&cfile->deferred)) {
 768                                 tmp_list = kmalloc(sizeof(struct file_list), GFP_ATOMIC);
 769                                 if (tmp_list == NULL)
 770                                         break;
 771                                 tmp_list->cfile = cfile;
 772                                 list_add_tail(&tmp_list->list, &file_head);
 773                         }
 774                 }
 775         }
 776         spin_unlock(&tcon->open_file_lock);
 777
 778         list_for_each_entry_safe(tmp_list, tmp_next_list, &file_head, list) {
 779                 _cifsFileInfo_put(tmp_list->cfile, true, false);
 780                 list_del(&tmp_list->list);
 781                 kfree(tmp_list);
 782         }
 783 }
 784 void
 785 cifs_close_deferred_file_under_dentry(struct cifs_tcon *tcon, const char *path)
 786 {
 787         struct cifsFileInfo *cfile;
 788         struct list_head *tmp;
 789         struct file_list *tmp_list, *tmp_next_list;
 790         struct list_head file_head;
 791         void *page;
 792         const char *full_path;
 793
 794         INIT_LIST_HEAD(&file_head);
 795         page = alloc_dentry_path();
 796         spin_lock(&tcon->open_file_lock);
 797         list_for_each(tmp, &tcon->openFileList) {
 798                 cfile = list_entry(tmp, struct cifsFileInfo, tlist);
 799                 full_path = build_path_from_dentry(cfile->dentry, page);
 800                 if (strstr(full_path, path)) {
 801                         if (delayed_work_pending(&cfile->deferred)) {
 802                                 if (cancel_delayed_work(&cfile->deferred)) {
 803                                         tmp_list = kmalloc(sizeof(struct file_list), GFP_ATOMIC);
 804                                         if (tmp_list == NULL)
 805                                                 break;
 806                                         tmp_list->cfile = cfile;
 807                                         list_add_tail(&tmp_list->list, &file_head);
 808                                 }
 809                         }
 810                 }
 811         }
 812         spin_unlock(&tcon->open_file_lock);
 813
 814         list_for_each_entry_safe(tmp_list, tmp_next_list, &file_head, list) {
 815                 _cifsFileInfo_put(tmp_list->cfile, true, false);
 816                 list_del(&tmp_list->list);
 817                 kfree(tmp_list);
 818         }
 819         free_dentry_path(page);
 820 }
 821
 822 /* parses DFS refferal V3 structure
 823  * caller is responsible for freeing target_nodes
 824  * returns:
 825  * - on success - 0
 826  * - on failure - errno
 827  */
 828 int
 829 parse_dfs_referrals(struct get_dfs_referral_rsp *rsp, u32 rsp_size,
 830                     unsigned int *num_of_nodes,
 831                     struct dfs_info3_param **target_nodes,
 832                     const struct nls_table *nls_codepage, int remap,
 833                     const char *searchName, bool is_unicode)
 834 {
 835         int i, rc = 0;
 836         char *data_end;
 837         struct dfs_referral_level_3 *ref;
 838
 839         *num_of_nodes = le16_to_cpu(rsp->NumberOfReferrals);
 840
 841         if (*num_of_nodes < 1) {
 842                 cifs_dbg(VFS, "num_referrals: must be at least > 0, but we get num_referrals = %d\n",
 843                          *num_of_nodes);
 844                 rc = -EINVAL;
 845                 goto parse_DFS_referrals_exit;
 846         }
 847
 848         ref = (struct dfs_referral_level_3 *) &(rsp->referrals);
 849         if (ref->VersionNumber != cpu_to_le16(3)) {
 850                 cifs_dbg(VFS, "Referrals of V%d version are not supported, should be V3\n",
 851                          le16_to_cpu(ref->VersionNumber));
 852                 rc = -EINVAL;
 853                 goto parse_DFS_referrals_exit;
 854         }
 855
 856         /* get the upper boundary of the resp buffer */
 857         data_end = (char *)rsp + rsp_size;
 858
 859         cifs_dbg(FYI, "num_referrals: %d dfs flags: 0x%x ...\n",
 860                  *num_of_nodes, le32_to_cpu(rsp->DFSFlags));
 861
 862         *target_nodes = kcalloc(*num_of_nodes, sizeof(struct dfs_info3_param),
 863                                 GFP_KERNEL);
 864         if (*target_nodes == NULL) {
 865                 rc = -ENOMEM;
 866                 goto parse_DFS_referrals_exit;
 867         }
 868
 869         /* collect necessary data from referrals */
 870         for (i = 0; i < *num_of_nodes; i++) {
 871                 char *temp;
 872                 int max_len;
 873                 struct dfs_info3_param *node = (*target_nodes)+i;
 874
 875                 node->flags = le32_to_cpu(rsp->DFSFlags);
 876                 if (is_unicode) {
 877                         __le16 *tmp = kmalloc(strlen(searchName)*2 + 2,
 878                                                 GFP_KERNEL);
 879                         if (tmp == NULL) {
 880                                 rc = -ENOMEM;
 881                                 goto parse_DFS_referrals_exit;
 882                         }
 883                         cifsConvertToUTF16((__le16 *) tmp, searchName,
 884                                            PATH_MAX, nls_codepage, remap);
 885                         node->path_consumed = cifs_utf16_bytes(tmp,
 886                                         le16_to_cpu(rsp->PathConsumed),
 887                                         nls_codepage);
 888                         kfree(tmp);
 889                 } else
 890                         node->path_consumed = le16_to_cpu(rsp->PathConsumed);
 891
 892                 node->server_type = le16_to_cpu(ref->ServerType);
 893                 node->ref_flag = le16_to_cpu(ref->ReferralEntryFlags);
 894
 895                 /* copy DfsPath */
 896                 temp = (char *)ref + le16_to_cpu(ref->DfsPathOffset);
 897                 max_len = data_end - temp;
 898                 node->path_name = cifs_strndup_from_utf16(temp, max_len,
 899                                                 is_unicode, nls_codepage);
 900                 if (!node->path_name) {
 901                         rc = -ENOMEM;
 902                         goto parse_DFS_referrals_exit;
 903                 }
 904
 905                 /* copy link target UNC */
 906                 temp = (char *)ref + le16_to_cpu(ref->NetworkAddressOffset);
 907                 max_len = data_end - temp;
 908                 node->node_name = cifs_strndup_from_utf16(temp, max_len,
 909                                                 is_unicode, nls_codepage);
 910                 if (!node->node_name) {
 911                         rc = -ENOMEM;
 912                         goto parse_DFS_referrals_exit;
 913                 }
 914
 915                 node->ttl = le32_to_cpu(ref->TimeToLive);
 916
 917                 ref++;
 918         }
 919
 920 parse_DFS_referrals_exit:
 921         if (rc) {
 922                 free_dfs_info_array(*target_nodes, *num_of_nodes);
 923                 *target_nodes = NULL;
 924                 *num_of_nodes = 0;
 925         }
 926         return rc;
 927 }
 928
 929 struct cifs_aio_ctx *
 930 cifs_aio_ctx_alloc(void)
 931 {
 932         struct cifs_aio_ctx *ctx;
 933
 934         /*
 935          * Must use kzalloc to initialize ctx->bv to NULL and ctx->direct_io
 936          * to false so that we know when we have to unreference pages within
 937          * cifs_aio_ctx_release()
 938          */
 939         ctx = kzalloc(sizeof(struct cifs_aio_ctx), GFP_KERNEL);
 940         if (!ctx)
 941                 return NULL;
 942
 943         INIT_LIST_HEAD(&ctx->list);
 944         mutex_init(&ctx->aio_mutex);
 945         init_completion(&ctx->done);
 946         kref_init(&ctx->refcount);
 947         return ctx;
 948 }
 949
 950 void
 951 cifs_aio_ctx_release(struct kref *refcount)
 952 {
 953         struct cifs_aio_ctx *ctx = container_of(refcount,
 954                                         struct cifs_aio_ctx, refcount);
 955
 956         cifsFileInfo_put(ctx->cfile);
 957
 958         /*
 959          * ctx->bv is only set if setup_aio_ctx_iter() was call successfuly
 960          * which means that iov_iter_get_pages() was a success and thus that
 961          * we have taken reference on pages.
 962          */
 963         if (ctx->bv) {
 964                 unsigned i;
 965
 966                 for (i = 0; i < ctx->npages; i++) {
 967                         if (ctx->should_dirty)
 968                                 set_page_dirty(ctx->bv[i].bv_page);
 969                         put_page(ctx->bv[i].bv_page);
 970                 }
 971                 kvfree(ctx->bv);
 972         }
 973
 974         kfree(ctx);
 975 }
 976
 977 #define CIFS_AIO_KMALLOC_LIMIT (1024 * 1024)
 978
 979 int
 980 setup_aio_ctx_iter(struct cifs_aio_ctx *ctx, struct iov_iter *iter, int rw)
 981 {
 982         ssize_t rc;
 983         unsigned int cur_npages;
 984         unsigned int npages = 0;
 985         unsigned int i;
 986         size_t len;
 987         size_t count = iov_iter_count(iter);
 988         unsigned int saved_len;
 989         size_t start;
 990         unsigned int max_pages = iov_iter_npages(iter, INT_MAX);
 991         struct page **pages = NULL;
 992         struct bio_vec *bv = NULL;
 993
 994         if (iov_iter_is_kvec(iter)) {
 995                 memcpy(&ctx->iter, iter, sizeof(*iter));
 996                 ctx->len = count;
 997                 iov_iter_advance(iter, count);
 998                 return 0;
 999         }
1000
1001         if (array_size(max_pages, sizeof(*bv)) <= CIFS_AIO_KMALLOC_LIMIT)
1002                 bv = kmalloc_array(max_pages, sizeof(*bv), GFP_KERNEL);
1003
1004         if (!bv) {
1005                 bv = vmalloc(array_size(max_pages, sizeof(*bv)));
1006                 if (!bv)
1007                         return -ENOMEM;
1008         }
1009
1010         if (array_size(max_pages, sizeof(*pages)) <= CIFS_AIO_KMALLOC_LIMIT)
1011                 pages = kmalloc_array(max_pages, sizeof(*pages), GFP_KERNEL);
1012
1013         if (!pages) {
1014                 pages = vmalloc(array_size(max_pages, sizeof(*pages)));
1015                 if (!pages) {
1016                         kvfree(bv);
1017                         return -ENOMEM;
1018                 }
1019         }
1020
1021         saved_len = count;
1022
1023         while (count && npages < max_pages) {
1024                 rc = iov_iter_get_pages(iter, pages, count, max_pages, &start);
1025                 if (rc < 0) {
1026                         cifs_dbg(VFS, "Couldn't get user pages (rc=%zd)\n", rc);
1027                         break;
1028                 }
1029
1030                 if (rc > count) {
1031                         cifs_dbg(VFS, "get pages rc=%zd more than %zu\n", rc,
1032                                  count);
1033                         break;
1034                 }
1035
1036                 iov_iter_advance(iter, rc);
1037                 count -= rc;
1038                 rc += start;
1039                 cur_npages = DIV_ROUND_UP(rc, PAGE_SIZE);
1040
1041                 if (npages + cur_npages > max_pages) {
1042                         cifs_dbg(VFS, "out of vec array capacity (%u vs %u)\n",
1043                                  npages + cur_npages, max_pages);
1044                         break;
1045                 }
1046
1047                 for (i = 0; i < cur_npages; i++) {
1048                         len = rc > PAGE_SIZE ? PAGE_SIZE : rc;
1049                         bv[npages + i].bv_page = pages[i];
1050                         bv[npages + i].bv_offset = start;
1051                         bv[npages + i].bv_len = len - start;
1052                         rc -= len;
1053                         start = 0;
1054                 }
1055
1056                 npages += cur_npages;
1057         }
1058
1059         kvfree(pages);
1060         ctx->bv = bv;
1061         ctx->len = saved_len - count;
1062         ctx->npages = npages;
1063         iov_iter_bvec(&ctx->iter, rw, ctx->bv, npages, ctx->len);
1064         return 0;
1065 }
1066
1067 /**
1068  * cifs_alloc_hash - allocate hash and hash context together
1069  * @name: The name of the crypto hash algo
1070  * @shash: Where to put the pointer to the hash algo
1071  * @sdesc: Where to put the pointer to the hash descriptor
1072  *
1073  * The caller has to make sure @sdesc is initialized to either NULL or
1074  * a valid context. Both can be freed via cifs_free_hash().
1075  */
1076 int
1077 cifs_alloc_hash(const char *name,
1078                 struct crypto_shash **shash, struct sdesc **sdesc)
1079 {
1080         int rc = 0;
1081         size_t size;
1082
1083         if (*sdesc != NULL)
1084                 return 0;
1085
1086         *shash = crypto_alloc_shash(name, 0, 0);
1087         if (IS_ERR(*shash)) {
1088                 cifs_dbg(VFS, "Could not allocate crypto %s\n", name);
1089                 rc = PTR_ERR(*shash);
1090                 *shash = NULL;
1091                 *sdesc = NULL;
1092                 return rc;
1093         }
1094
1095         size = sizeof(struct shash_desc) + crypto_shash_descsize(*shash);
1096         *sdesc = kmalloc(size, GFP_KERNEL);
1097         if (*sdesc == NULL) {
1098                 cifs_dbg(VFS, "no memory left to allocate crypto %s\n", name);
1099                 crypto_free_shash(*shash);
1100                 *shash = NULL;
1101                 return -ENOMEM;
1102         }
1103
1104         (*sdesc)->shash.tfm = *shash;
1105         return 0;
1106 }
1107
1108 /**
1109  * cifs_free_hash - free hash and hash context together
1110  * @shash: Where to find the pointer to the hash algo
1111  * @sdesc: Where to find the pointer to the hash descriptor
1112  *
1113  * Freeing a NULL hash or context is safe.
1114  */
1115 void
1116 cifs_free_hash(struct crypto_shash **shash, struct sdesc **sdesc)
1117 {
1118         kfree(*sdesc);
1119         *sdesc = NULL;
1120         if (*shash)
1121                 crypto_free_shash(*shash);
1122         *shash = NULL;
1123 }
1124
1125 /**
1126  * rqst_page_get_length - obtain the length and offset for a page in smb_rqst
1127  * @rqst: The request descriptor
1128  * @page: The index of the page to query
1129  * @len: Where to store the length for this page:
1130  * @offset: Where to store the offset for this page
1131  */
1132 void rqst_page_get_length(struct smb_rqst *rqst, unsigned int page,
1133                                 unsigned int *len, unsigned int *offset)
1134 {
1135         *len = rqst->rq_pagesz;
1136         *offset = (page == 0) ? rqst->rq_offset : 0;
1137
1138         if (rqst->rq_npages == 1 || page == rqst->rq_npages-1)
1139                 *len = rqst->rq_tailsz;
1140         else if (page == 0)
1141                 *len = rqst->rq_pagesz - rqst->rq_offset;
1142 }
1143
1144 void extract_unc_hostname(const char *unc, const char **h, size_t *len)
1145 {
1146         const char *end;
1147
1148         /* skip initial slashes */
1149         while (*unc && (*unc == '\\' || *unc == '/'))
1150                 unc++;
1151
1152         end = unc;
1153
1154         while (*end && !(*end == '\\' || *end == '/'))
1155                 end++;
1156
1157         *h = unc;
1158         *len = end - unc;
1159 }
1160
1161 /**
1162  * copy_path_name - copy src path to dst, possibly truncating
1163  * @dst: The destination buffer
1164  * @src: The source name
1165  *
1166  * returns number of bytes written (including trailing nul)
1167  */
1168 int copy_path_name(char *dst, const char *src)
1169 {
1170         int name_len;
1171
1172         /*
1173          * PATH_MAX includes nul, so if strlen(src) >= PATH_MAX it
1174          * will truncate and strlen(dst) will be PATH_MAX-1
1175          */
1176         name_len = strscpy(dst, src, PATH_MAX);
1177         if (WARN_ON_ONCE(name_len < 0))
1178                 name_len = PATH_MAX-1;
1179
1180         /* we count the trailing nul */
1181         name_len++;
1182         return name_len;
1183 }
1184
1185 struct super_cb_data {
1186         void *data;
1187         struct super_block *sb;
1188 };
1189
1190 static void tcp_super_cb(struct super_block *sb, void *arg)
1191 {
1192         struct super_cb_data *sd = arg;
1193         struct TCP_Server_Info *server = sd->data;
1194         struct cifs_sb_info *cifs_sb;
1195         struct cifs_tcon *tcon;
1196
1197         if (sd->sb)
1198                 return;
1199
1200         cifs_sb = CIFS_SB(sb);
1201         tcon = cifs_sb_master_tcon(cifs_sb);
1202         if (tcon->ses->server == server)
1203                 sd->sb = sb;
1204 }
1205
1206 static struct super_block *__cifs_get_super(void (*f)(struct super_block *, void *),
1207                                             void *data)
1208 {
1209         struct super_cb_data sd = {
1210                 .data = data,
1211                 .sb = NULL,
1212         };
1213
1214         iterate_supers_type(&cifs_fs_type, f, &sd);
1215
1216         if (!sd.sb)
1217                 return ERR_PTR(-EINVAL);
1218         /*
1219          * Grab an active reference in order to prevent automounts (DFS links)
1220          * of expiring and then freeing up our cifs superblock pointer while
1221          * we're doing failover.
1222          */
1223         cifs_sb_active(sd.sb);
1224         return sd.sb;
1225 }
1226
1227 static void __cifs_put_super(struct super_block *sb)
1228 {
1229         if (!IS_ERR_OR_NULL(sb))
1230                 cifs_sb_deactive(sb);
1231 }
1232
1233 struct super_block *cifs_get_tcp_super(struct TCP_Server_Info *server)
1234 {
1235         return __cifs_get_super(tcp_super_cb, server);
1236 }
1237
1238 void cifs_put_tcp_super(struct super_block *sb)
1239 {
1240         __cifs_put_super(sb);
1241 }
1242
1243 #ifdef CONFIG_CIFS_DFS_UPCALL
1244 int match_target_ip(struct TCP_Server_Info *server,
1245                     const char *share, size_t share_len,
1246                     bool *result)
1247 {
1248         int rc;
1249         char *target, *tip = NULL;
1250         struct sockaddr tipaddr;
1251
1252         *result = false;
1253
1254         target = kzalloc(share_len + 3, GFP_KERNEL);
1255         if (!target) {
1256                 rc = -ENOMEM;
1257                 goto out;
1258         }
1259
1260         scnprintf(target, share_len + 3, "\\\\%.*s", (int)share_len, share);
1261
1262         cifs_dbg(FYI, "%s: target name: %s\n", __func__, target + 2);
1263
1264         rc = dns_resolve_server_name_to_ip(target, &tip, NULL);
1265         if (rc < 0)
1266                 goto out;
1267
1268         cifs_dbg(FYI, "%s: target ip: %s\n", __func__, tip);
1269
1270         if (!cifs_convert_address(&tipaddr, tip, strlen(tip))) {
1271                 cifs_dbg(VFS, "%s: failed to convert target ip address\n",
1272                          __func__);
1273                 rc = -EINVAL;
1274                 goto out;
1275         }
1276
1277         *result = cifs_match_ipaddr((struct sockaddr *)&server->dstaddr,
1278                                     &tipaddr);
1279         cifs_dbg(FYI, "%s: ip addresses match: %u\n", __func__, *result);
1280         rc = 0;
1281
1282 out:
1283         kfree(target);
1284         kfree(tip);
1285
1286         return rc;
1287 }
1288
1289 int cifs_update_super_prepath(struct cifs_sb_info *cifs_sb, char *prefix)
1290 {
1291         kfree(cifs_sb->prepath);
1292
1293         if (prefix && *prefix) {
1294                 cifs_sb->prepath = kstrdup(prefix, GFP_ATOMIC);
1295                 if (!cifs_sb->prepath)
1296                         return -ENOMEM;
1297
1298                 convert_delimiter(cifs_sb->prepath, CIFS_DIR_SEP(cifs_sb));
1299         } else
1300                 cifs_sb->prepath = NULL;
1301
1302         cifs_sb->mnt_cifs_flags |= CIFS_MOUNT_USE_PREFIX_PATH;
1303         return 0;
1304 }
1305
1306 /** cifs_dfs_query_info_nonascii_quirk
1307  * Handle weird Windows SMB server behaviour. It responds with
1308  * STATUS_OBJECT_NAME_INVALID code to SMB2 QUERY_INFO request
1309  * for "\<server>\<dfsname>\<linkpath>" DFS reference,
1310  * where <dfsname> contains non-ASCII unicode symbols.
1311  *
1312  * Check such DFS reference and emulate -ENOENT if it is actual.
1313  */
1314 int cifs_dfs_query_info_nonascii_quirk(const unsigned int xid,
1315                                        struct cifs_tcon *tcon,
1316                                        struct cifs_sb_info *cifs_sb,
1317                                        const char *linkpath)
1318 {
1319         char *treename, *dfspath, sep;
1320         int treenamelen, linkpathlen, rc;
1321
1322         treename = tcon->treeName;
1323         /* MS-DFSC: All paths in REQ_GET_DFS_REFERRAL and RESP_GET_DFS_REFERRAL
1324          * messages MUST be encoded with exactly one leading backslash, not two
1325          * leading backslashes.
1326          */
1327         sep = CIFS_DIR_SEP(cifs_sb);
1328         if (treename[0] == sep && treename[1] == sep)
1329                 treename++;
1330         linkpathlen = strlen(linkpath);
1331         treenamelen = strnlen(treename, MAX_TREE_SIZE + 1);
1332         dfspath = kzalloc(treenamelen + linkpathlen + 1, GFP_KERNEL);
1333         if (!dfspath)
1334                 return -ENOMEM;
1335         if (treenamelen)
1336                 memcpy(dfspath, treename, treenamelen);
1337         memcpy(dfspath + treenamelen, linkpath, linkpathlen);
1338         rc = dfs_cache_find(xid, tcon->ses, cifs_sb->local_nls,
1339                             cifs_remap(cifs_sb), dfspath, NULL, NULL);
1340         if (rc == 0) {
1341                 cifs_dbg(FYI, "DFS ref '%s' is found, emulate -EREMOTE\n",
1342                          dfspath);
1343                 rc = -EREMOTE;
1344         } else if (rc == -EEXIST) {
1345                 cifs_dbg(FYI, "DFS ref '%s' is not found, emulate -ENOENT\n",
1346                          dfspath);
1347                 rc = -ENOENT;
1348         } else {
1349                 cifs_dbg(FYI, "%s: dfs_cache_find returned %d\n", __func__, rc);
1350         }
1351         kfree(dfspath);
1352         return rc;
1353 }
1354 #endif