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 (sfrench@us.ibm.com)
   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 #include "cached_dir.h"
  27
  28 extern mempool_t *cifs_sm_req_poolp;
  29 extern mempool_t *cifs_req_poolp;
  30
  31 /* The xid serves as a useful identifier for each incoming vfs request,
  32    in a similar way to the mid which is useful to track each sent smb,
  33    and CurrentXid can also provide a running counter (although it
  34    will eventually wrap past zero) of the total vfs operations handled
  35    since the cifs fs was mounted */
  36
  37 unsigned int
  38 _get_xid(void)
  39 {
  40         unsigned int xid;
  41
  42         spin_lock(&GlobalMid_Lock);
  43         GlobalTotalActiveXid++;
  44
  45         /* keep high water mark for number of simultaneous ops in filesystem */
  46         if (GlobalTotalActiveXid > GlobalMaxActiveXid)
  47                 GlobalMaxActiveXid = GlobalTotalActiveXid;
  48         if (GlobalTotalActiveXid > 65000)
  49                 cifs_dbg(FYI, "warning: more than 65000 requests active\n");
  50         xid = GlobalCurrentXid++;
  51         spin_unlock(&GlobalMid_Lock);
  52         return xid;
  53 }
  54
  55 void
  56 _free_xid(unsigned int xid)
  57 {
  58         spin_lock(&GlobalMid_Lock);
  59         /* if (GlobalTotalActiveXid == 0)
  60                 BUG(); */
  61         GlobalTotalActiveXid--;
  62         spin_unlock(&GlobalMid_Lock);
  63 }
  64
  65 struct cifs_ses *
  66 sesInfoAlloc(void)
  67 {
  68         struct cifs_ses *ret_buf;
  69
  70         ret_buf = kzalloc(sizeof(struct cifs_ses), GFP_KERNEL);
  71         if (ret_buf) {
  72                 atomic_inc(&sesInfoAllocCount);
  73                 spin_lock_init(&ret_buf->ses_lock);
  74                 ret_buf->ses_status = SES_NEW;
  75                 ++ret_buf->ses_count;
  76                 INIT_LIST_HEAD(&ret_buf->smb_ses_list);
  77                 INIT_LIST_HEAD(&ret_buf->tcon_list);
  78                 mutex_init(&ret_buf->session_mutex);
  79                 spin_lock_init(&ret_buf->iface_lock);
  80                 INIT_LIST_HEAD(&ret_buf->iface_list);
  81                 spin_lock_init(&ret_buf->chan_lock);
  82         }
  83         return ret_buf;
  84 }
  85
  86 void
  87 sesInfoFree(struct cifs_ses *buf_to_free)
  88 {
  89         struct cifs_server_iface *iface = NULL, *niface = NULL;
  90
  91         if (buf_to_free == NULL) {
  92                 cifs_dbg(FYI, "Null buffer passed to sesInfoFree\n");
  93                 return;
  94         }
  95
  96         atomic_dec(&sesInfoAllocCount);
  97         kfree(buf_to_free->serverOS);
  98         kfree(buf_to_free->serverDomain);
  99         kfree(buf_to_free->serverNOS);
 100         kfree_sensitive(buf_to_free->password);
 101         kfree(buf_to_free->user_name);
 102         kfree(buf_to_free->domainName);
 103         kfree_sensitive(buf_to_free->auth_key.response);
 104         spin_lock(&buf_to_free->iface_lock);
 105         list_for_each_entry_safe(iface, niface, &buf_to_free->iface_list,
 106                                  iface_head)
 107                 kref_put(&iface->refcount, release_iface);
 108         spin_unlock(&buf_to_free->iface_lock);
 109         kfree_sensitive(buf_to_free);
 110 }
 111
 112 struct cifs_tcon *
 113 tconInfoAlloc(void)
 114 {
 115         struct cifs_tcon *ret_buf;
 116
 117         ret_buf = kzalloc(sizeof(*ret_buf), GFP_KERNEL);
 118         if (!ret_buf)
 119                 return NULL;
 120         ret_buf->cfid = init_cached_dir();
 121         if (!ret_buf->cfid) {
 122                 kfree(ret_buf);
 123                 return NULL;
 124         }
 125
 126         atomic_inc(&tconInfoAllocCount);
 127         ret_buf->status = TID_NEW;
 128         ++ret_buf->tc_count;
 129         spin_lock_init(&ret_buf->tc_lock);
 130         INIT_LIST_HEAD(&ret_buf->openFileList);
 131         INIT_LIST_HEAD(&ret_buf->tcon_list);
 132         spin_lock_init(&ret_buf->open_file_lock);
 133         spin_lock_init(&ret_buf->stat_lock);
 134         atomic_set(&ret_buf->num_local_opens, 0);
 135         atomic_set(&ret_buf->num_remote_opens, 0);
 136
 137         return ret_buf;
 138 }
 139
 140 void
 141 tconInfoFree(struct cifs_tcon *tcon)
 142 {
 143         if (tcon == NULL) {
 144                 cifs_dbg(FYI, "Null buffer passed to tconInfoFree\n");
 145                 return;
 146         }
 147         free_cached_dir(tcon);
 148         atomic_dec(&tconInfoAllocCount);
 149         kfree(tcon->nativeFileSystem);
 150         kfree_sensitive(tcon->password);
 151         kfree(tcon);
 152 }
 153
 154 struct smb_hdr *
 155 cifs_buf_get(void)
 156 {
 157         struct smb_hdr *ret_buf = NULL;
 158         /*
 159          * SMB2 header is bigger than CIFS one - no problems to clean some
 160          * more bytes for CIFS.
 161          */
 162         size_t buf_size = sizeof(struct smb2_hdr);
 163
 164         /*
 165          * We could use negotiated size instead of max_msgsize -
 166          * but it may be more efficient to always alloc same size
 167          * albeit slightly larger than necessary and maxbuffersize
 168          * defaults to this and can not be bigger.
 169          */
 170         ret_buf = mempool_alloc(cifs_req_poolp, GFP_NOFS);
 171
 172         /* clear the first few header bytes */
 173         /* for most paths, more is cleared in header_assemble */
 174         memset(ret_buf, 0, buf_size + 3);
 175         atomic_inc(&buf_alloc_count);
 176 #ifdef CONFIG_CIFS_STATS2
 177         atomic_inc(&total_buf_alloc_count);
 178 #endif /* CONFIG_CIFS_STATS2 */
 179
 180         return ret_buf;
 181 }
 182
 183 void
 184 cifs_buf_release(void *buf_to_free)
 185 {
 186         if (buf_to_free == NULL) {
 187                 /* cifs_dbg(FYI, "Null buffer passed to cifs_buf_release\n");*/
 188                 return;
 189         }
 190         mempool_free(buf_to_free, cifs_req_poolp);
 191
 192         atomic_dec(&buf_alloc_count);
 193         return;
 194 }
 195
 196 struct smb_hdr *
 197 cifs_small_buf_get(void)
 198 {
 199         struct smb_hdr *ret_buf = NULL;
 200
 201 /* We could use negotiated size instead of max_msgsize -
 202    but it may be more efficient to always alloc same size
 203    albeit slightly larger than necessary and maxbuffersize
 204    defaults to this and can not be bigger */
 205         ret_buf = mempool_alloc(cifs_sm_req_poolp, GFP_NOFS);
 206         /* No need to clear memory here, cleared in header assemble */
 207         /*      memset(ret_buf, 0, sizeof(struct smb_hdr) + 27);*/
 208         atomic_inc(&small_buf_alloc_count);
 209 #ifdef CONFIG_CIFS_STATS2
 210         atomic_inc(&total_small_buf_alloc_count);
 211 #endif /* CONFIG_CIFS_STATS2 */
 212
 213         return ret_buf;
 214 }
 215
 216 void
 217 cifs_small_buf_release(void *buf_to_free)
 218 {
 219
 220         if (buf_to_free == NULL) {
 221                 cifs_dbg(FYI, "Null buffer passed to cifs_small_buf_release\n");
 222                 return;
 223         }
 224         mempool_free(buf_to_free, cifs_sm_req_poolp);
 225
 226         atomic_dec(&small_buf_alloc_count);
 227         return;
 228 }
 229
 230 void
 231 free_rsp_buf(int resp_buftype, void *rsp)
 232 {
 233         if (resp_buftype == CIFS_SMALL_BUFFER)
 234                 cifs_small_buf_release(rsp);
 235         else if (resp_buftype == CIFS_LARGE_BUFFER)
 236                 cifs_buf_release(rsp);
 237 }
 238
 239 /* NB: MID can not be set if treeCon not passed in, in that
 240    case it is responsbility of caller to set the mid */
 241 void
 242 header_assemble(struct smb_hdr *buffer, char smb_command /* command */ ,
 243                 const struct cifs_tcon *treeCon, int word_count
 244                 /* length of fixed section (word count) in two byte units  */)
 245 {
 246         char *temp = (char *) buffer;
 247
 248         memset(temp, 0, 256); /* bigger than MAX_CIFS_HDR_SIZE */
 249
 250         buffer->smb_buf_length = cpu_to_be32(
 251             (2 * word_count) + sizeof(struct smb_hdr) -
 252             4 /*  RFC 1001 length field does not count */  +
 253             2 /* for bcc field itself */) ;
 254
 255         buffer->Protocol[0] = 0xFF;
 256         buffer->Protocol[1] = 'S';
 257         buffer->Protocol[2] = 'M';
 258         buffer->Protocol[3] = 'B';
 259         buffer->Command = smb_command;
 260         buffer->Flags = 0x00;   /* case sensitive */
 261         buffer->Flags2 = SMBFLG2_KNOWS_LONG_NAMES;
 262         buffer->Pid = cpu_to_le16((__u16)current->tgid);
 263         buffer->PidHigh = cpu_to_le16((__u16)(current->tgid >> 16));
 264         if (treeCon) {
 265                 buffer->Tid = treeCon->tid;
 266                 if (treeCon->ses) {
 267                         if (treeCon->ses->capabilities & CAP_UNICODE)
 268                                 buffer->Flags2 |= SMBFLG2_UNICODE;
 269                         if (treeCon->ses->capabilities & CAP_STATUS32)
 270                                 buffer->Flags2 |= SMBFLG2_ERR_STATUS;
 271
 272                         /* Uid is not converted */
 273                         buffer->Uid = treeCon->ses->Suid;
 274                         if (treeCon->ses->server)
 275                                 buffer->Mid = get_next_mid(treeCon->ses->server);
 276                 }
 277                 if (treeCon->Flags & SMB_SHARE_IS_IN_DFS)
 278                         buffer->Flags2 |= SMBFLG2_DFS;
 279                 if (treeCon->nocase)
 280                         buffer->Flags  |= SMBFLG_CASELESS;
 281                 if ((treeCon->ses) && (treeCon->ses->server))
 282                         if (treeCon->ses->server->sign)
 283                                 buffer->Flags2 |= SMBFLG2_SECURITY_SIGNATURE;
 284         }
 285
 286 /*  endian conversion of flags is now done just before sending */
 287         buffer->WordCount = (char) word_count;
 288         return;
 289 }
 290
 291 static int
 292 check_smb_hdr(struct smb_hdr *smb)
 293 {
 294         /* does it have the right SMB "signature" ? */
 295         if (*(__le32 *) smb->Protocol != cpu_to_le32(0x424d53ff)) {
 296                 cifs_dbg(VFS, "Bad protocol string signature header 0x%x\n",
 297                          *(unsigned int *)smb->Protocol);
 298                 return 1;
 299         }
 300
 301         /* if it's a response then accept */
 302         if (smb->Flags & SMBFLG_RESPONSE)
 303                 return 0;
 304
 305         /* only one valid case where server sends us request */
 306         if (smb->Command == SMB_COM_LOCKING_ANDX)
 307                 return 0;
 308
 309         cifs_dbg(VFS, "Server sent request, not response. mid=%u\n",
 310                  get_mid(smb));
 311         return 1;
 312 }
 313
 314 int
 315 checkSMB(char *buf, unsigned int total_read, struct TCP_Server_Info *server)
 316 {
 317         struct smb_hdr *smb = (struct smb_hdr *)buf;
 318         __u32 rfclen = be32_to_cpu(smb->smb_buf_length);
 319         __u32 clc_len;  /* calculated length */
 320         cifs_dbg(FYI, "checkSMB Length: 0x%x, smb_buf_length: 0x%x\n",
 321                  total_read, rfclen);
 322
 323         /* is this frame too small to even get to a BCC? */
 324         if (total_read < 2 + sizeof(struct smb_hdr)) {
 325                 if ((total_read >= sizeof(struct smb_hdr) - 1)
 326                             && (smb->Status.CifsError != 0)) {
 327                         /* it's an error return */
 328                         smb->WordCount = 0;
 329                         /* some error cases do not return wct and bcc */
 330                         return 0;
 331                 } else if ((total_read == sizeof(struct smb_hdr) + 1) &&
 332                                 (smb->WordCount == 0)) {
 333                         char *tmp = (char *)smb;
 334                         /* Need to work around a bug in two servers here */
 335                         /* First, check if the part of bcc they sent was zero */
 336                         if (tmp[sizeof(struct smb_hdr)] == 0) {
 337                                 /* some servers return only half of bcc
 338                                  * on simple responses (wct, bcc both zero)
 339                                  * in particular have seen this on
 340                                  * ulogoffX and FindClose. This leaves
 341                                  * one byte of bcc potentially unitialized
 342                                  */
 343                                 /* zero rest of bcc */
 344                                 tmp[sizeof(struct smb_hdr)+1] = 0;
 345                                 return 0;
 346                         }
 347                         cifs_dbg(VFS, "rcvd invalid byte count (bcc)\n");
 348                 } else {
 349                         cifs_dbg(VFS, "Length less than smb header size\n");
 350                 }
 351                 return -EIO;
 352         }
 353
 354         /* otherwise, there is enough to get to the BCC */
 355         if (check_smb_hdr(smb))
 356                 return -EIO;
 357         clc_len = smbCalcSize(smb, server);
 358
 359         if (4 + rfclen != total_read) {
 360                 cifs_dbg(VFS, "Length read does not match RFC1001 length %d\n",
 361                          rfclen);
 362                 return -EIO;
 363         }
 364
 365         if (4 + rfclen != clc_len) {
 366                 __u16 mid = get_mid(smb);
 367                 /* check if bcc wrapped around for large read responses */
 368                 if ((rfclen > 64 * 1024) && (rfclen > clc_len)) {
 369                         /* check if lengths match mod 64K */
 370                         if (((4 + rfclen) & 0xFFFF) == (clc_len & 0xFFFF))
 371                                 return 0; /* bcc wrapped */
 372                 }
 373                 cifs_dbg(FYI, "Calculated size %u vs length %u mismatch for mid=%u\n",
 374                          clc_len, 4 + rfclen, mid);
 375
 376                 if (4 + rfclen < clc_len) {
 377                         cifs_dbg(VFS, "RFC1001 size %u smaller than SMB for mid=%u\n",
 378                                  rfclen, mid);
 379                         return -EIO;
 380                 } else if (rfclen > clc_len + 512) {
 381                         /*
 382                          * Some servers (Windows XP in particular) send more
 383                          * data than the lengths in the SMB packet would
 384                          * indicate on certain calls (byte range locks and
 385                          * trans2 find first calls in particular). While the
 386                          * client can handle such a frame by ignoring the
 387                          * trailing data, we choose limit the amount of extra
 388                          * data to 512 bytes.
 389                          */
 390                         cifs_dbg(VFS, "RFC1001 size %u more than 512 bytes larger than SMB for mid=%u\n",
 391                                  rfclen, mid);
 392                         return -EIO;
 393                 }
 394         }
 395         return 0;
 396 }
 397
 398 bool
 399 is_valid_oplock_break(char *buffer, struct TCP_Server_Info *srv)
 400 {
 401         struct smb_hdr *buf = (struct smb_hdr *)buffer;
 402         struct smb_com_lock_req *pSMB = (struct smb_com_lock_req *)buf;
 403         struct cifs_ses *ses;
 404         struct cifs_tcon *tcon;
 405         struct cifsInodeInfo *pCifsInode;
 406         struct cifsFileInfo *netfile;
 407
 408         cifs_dbg(FYI, "Checking for oplock break or dnotify response\n");
 409         if ((pSMB->hdr.Command == SMB_COM_NT_TRANSACT) &&
 410            (pSMB->hdr.Flags & SMBFLG_RESPONSE)) {
 411                 struct smb_com_transaction_change_notify_rsp *pSMBr =
 412                         (struct smb_com_transaction_change_notify_rsp *)buf;
 413                 struct file_notify_information *pnotify;
 414                 __u32 data_offset = 0;
 415                 size_t len = srv->total_read - sizeof(pSMBr->hdr.smb_buf_length);
 416
 417                 if (get_bcc(buf) > sizeof(struct file_notify_information)) {
 418                         data_offset = le32_to_cpu(pSMBr->DataOffset);
 419
 420                         if (data_offset >
 421                             len - sizeof(struct file_notify_information)) {
 422                                 cifs_dbg(FYI, "Invalid data_offset %u\n",
 423                                          data_offset);
 424                                 return true;
 425                         }
 426                         pnotify = (struct file_notify_information *)
 427                                 ((char *)&pSMBr->hdr.Protocol + data_offset);
 428                         cifs_dbg(FYI, "dnotify on %s Action: 0x%x\n",
 429                                  pnotify->FileName, pnotify->Action);
 430                         /*   cifs_dump_mem("Rcvd notify Data: ",buf,
 431                                 sizeof(struct smb_hdr)+60); */
 432                         return true;
 433                 }
 434                 if (pSMBr->hdr.Status.CifsError) {
 435                         cifs_dbg(FYI, "notify err 0x%x\n",
 436                                  pSMBr->hdr.Status.CifsError);
 437                         return true;
 438                 }
 439                 return false;
 440         }
 441         if (pSMB->hdr.Command != SMB_COM_LOCKING_ANDX)
 442                 return false;
 443         if (pSMB->hdr.Flags & SMBFLG_RESPONSE) {
 444                 /* no sense logging error on invalid handle on oplock
 445                    break - harmless race between close request and oplock
 446                    break response is expected from time to time writing out
 447                    large dirty files cached on the client */
 448                 if ((NT_STATUS_INVALID_HANDLE) ==
 449                    le32_to_cpu(pSMB->hdr.Status.CifsError)) {
 450                         cifs_dbg(FYI, "Invalid handle on oplock break\n");
 451                         return true;
 452                 } else if (ERRbadfid ==
 453                    le16_to_cpu(pSMB->hdr.Status.DosError.Error)) {
 454                         return true;
 455                 } else {
 456                         return false; /* on valid oplock brk we get "request" */
 457                 }
 458         }
 459         if (pSMB->hdr.WordCount != 8)
 460                 return false;
 461
 462         cifs_dbg(FYI, "oplock type 0x%x level 0x%x\n",
 463                  pSMB->LockType, pSMB->OplockLevel);
 464         if (!(pSMB->LockType & LOCKING_ANDX_OPLOCK_RELEASE))
 465                 return false;
 466
 467         /* look up tcon based on tid & uid */
 468         spin_lock(&cifs_tcp_ses_lock);
 469         list_for_each_entry(ses, &srv->smb_ses_list, smb_ses_list) {
 470                 list_for_each_entry(tcon, &ses->tcon_list, tcon_list) {
 471                         if (tcon->tid != buf->Tid)
 472                                 continue;
 473
 474                         cifs_stats_inc(&tcon->stats.cifs_stats.num_oplock_brks);
 475                         spin_lock(&tcon->open_file_lock);
 476                         list_for_each_entry(netfile, &tcon->openFileList, tlist) {
 477                                 if (pSMB->Fid != netfile->fid.netfid)
 478                                         continue;
 479
 480                                 cifs_dbg(FYI, "file id match, oplock break\n");
 481                                 pCifsInode = CIFS_I(d_inode(netfile->dentry));
 482
 483                                 set_bit(CIFS_INODE_PENDING_OPLOCK_BREAK,
 484                                         &pCifsInode->flags);
 485
 486                                 netfile->oplock_epoch = 0;
 487                                 netfile->oplock_level = pSMB->OplockLevel;
 488                                 netfile->oplock_break_cancelled = false;
 489                                 cifs_queue_oplock_break(netfile);
 490
 491                                 spin_unlock(&tcon->open_file_lock);
 492                                 spin_unlock(&cifs_tcp_ses_lock);
 493                                 return true;
 494                         }
 495                         spin_unlock(&tcon->open_file_lock);
 496                         spin_unlock(&cifs_tcp_ses_lock);
 497                         cifs_dbg(FYI, "No matching file for oplock break\n");
 498                         return true;
 499                 }
 500         }
 501         spin_unlock(&cifs_tcp_ses_lock);
 502         cifs_dbg(FYI, "Can not process oplock break for non-existent connection\n");
 503         return true;
 504 }
 505
 506 void
 507 dump_smb(void *buf, int smb_buf_length)
 508 {
 509         if (traceSMB == 0)
 510                 return;
 511
 512         print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_NONE, 8, 2, buf,
 513                        smb_buf_length, true);
 514 }
 515
 516 void
 517 cifs_autodisable_serverino(struct cifs_sb_info *cifs_sb)
 518 {
 519         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SERVER_INUM) {
 520                 struct cifs_tcon *tcon = NULL;
 521
 522                 if (cifs_sb->master_tlink)
 523                         tcon = cifs_sb_master_tcon(cifs_sb);
 524
 525                 cifs_sb->mnt_cifs_flags &= ~CIFS_MOUNT_SERVER_INUM;
 526                 cifs_sb->mnt_cifs_serverino_autodisabled = true;
 527                 cifs_dbg(VFS, "Autodisabling the use of server inode numbers on %s\n",
 528                          tcon ? tcon->treeName : "new server");
 529                 cifs_dbg(VFS, "The server doesn't seem to support them properly or the files might be on different servers (DFS)\n");
 530                 cifs_dbg(VFS, "Hardlinks will not be recognized on this mount. Consider mounting with the \"noserverino\" option to silence this message.\n");
 531
 532         }
 533 }
 534
 535 void cifs_set_oplock_level(struct cifsInodeInfo *cinode, __u32 oplock)
 536 {
 537         oplock &= 0xF;
 538
 539         if (oplock == OPLOCK_EXCLUSIVE) {
 540                 cinode->oplock = CIFS_CACHE_WRITE_FLG | CIFS_CACHE_READ_FLG;
 541                 cifs_dbg(FYI, "Exclusive Oplock granted on inode %p\n",
 542                          &cinode->netfs.inode);
 543         } else if (oplock == OPLOCK_READ) {
 544                 cinode->oplock = CIFS_CACHE_READ_FLG;
 545                 cifs_dbg(FYI, "Level II Oplock granted on inode %p\n",
 546                          &cinode->netfs.inode);
 547         } else
 548                 cinode->oplock = 0;
 549 }
 550
 551 /*
 552  * We wait for oplock breaks to be processed before we attempt to perform
 553  * writes.
 554  */
 555 int cifs_get_writer(struct cifsInodeInfo *cinode)
 556 {
 557         int rc;
 558
 559 start:
 560         rc = wait_on_bit(&cinode->flags, CIFS_INODE_PENDING_OPLOCK_BREAK,
 561                          TASK_KILLABLE);
 562         if (rc)
 563                 return rc;
 564
 565         spin_lock(&cinode->writers_lock);
 566         if (!cinode->writers)
 567                 set_bit(CIFS_INODE_PENDING_WRITERS, &cinode->flags);
 568         cinode->writers++;
 569         /* Check to see if we have started servicing an oplock break */
 570         if (test_bit(CIFS_INODE_PENDING_OPLOCK_BREAK, &cinode->flags)) {
 571                 cinode->writers--;
 572                 if (cinode->writers == 0) {
 573                         clear_bit(CIFS_INODE_PENDING_WRITERS, &cinode->flags);
 574                         wake_up_bit(&cinode->flags, CIFS_INODE_PENDING_WRITERS);
 575                 }
 576                 spin_unlock(&cinode->writers_lock);
 577                 goto start;
 578         }
 579         spin_unlock(&cinode->writers_lock);
 580         return 0;
 581 }
 582
 583 void cifs_put_writer(struct cifsInodeInfo *cinode)
 584 {
 585         spin_lock(&cinode->writers_lock);
 586         cinode->writers--;
 587         if (cinode->writers == 0) {
 588                 clear_bit(CIFS_INODE_PENDING_WRITERS, &cinode->flags);
 589                 wake_up_bit(&cinode->flags, CIFS_INODE_PENDING_WRITERS);
 590         }
 591         spin_unlock(&cinode->writers_lock);
 592 }
 593
 594 /**
 595  * cifs_queue_oplock_break - queue the oplock break handler for cfile
 596  * @cfile: The file to break the oplock on
 597  *
 598  * This function is called from the demultiplex thread when it
 599  * receives an oplock break for @cfile.
 600  *
 601  * Assumes the tcon->open_file_lock is held.
 602  * Assumes cfile->file_info_lock is NOT held.
 603  */
 604 void cifs_queue_oplock_break(struct cifsFileInfo *cfile)
 605 {
 606         /*
 607          * Bump the handle refcount now while we hold the
 608          * open_file_lock to enforce the validity of it for the oplock
 609          * break handler. The matching put is done at the end of the
 610          * handler.
 611          */
 612         cifsFileInfo_get(cfile);
 613
 614         queue_work(cifsoplockd_wq, &cfile->oplock_break);
 615 }
 616
 617 void cifs_done_oplock_break(struct cifsInodeInfo *cinode)
 618 {
 619         clear_bit(CIFS_INODE_PENDING_OPLOCK_BREAK, &cinode->flags);
 620         wake_up_bit(&cinode->flags, CIFS_INODE_PENDING_OPLOCK_BREAK);
 621 }
 622
 623 bool
 624 backup_cred(struct cifs_sb_info *cifs_sb)
 625 {
 626         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_BACKUPUID) {
 627                 if (uid_eq(cifs_sb->ctx->backupuid, current_fsuid()))
 628                         return true;
 629         }
 630         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_BACKUPGID) {
 631                 if (in_group_p(cifs_sb->ctx->backupgid))
 632                         return true;
 633         }
 634
 635         return false;
 636 }
 637
 638 void
 639 cifs_del_pending_open(struct cifs_pending_open *open)
 640 {
 641         spin_lock(&tlink_tcon(open->tlink)->open_file_lock);
 642         list_del(&open->olist);
 643         spin_unlock(&tlink_tcon(open->tlink)->open_file_lock);
 644 }
 645
 646 void
 647 cifs_add_pending_open_locked(struct cifs_fid *fid, struct tcon_link *tlink,
 648                              struct cifs_pending_open *open)
 649 {
 650         memcpy(open->lease_key, fid->lease_key, SMB2_LEASE_KEY_SIZE);
 651         open->oplock = CIFS_OPLOCK_NO_CHANGE;
 652         open->tlink = tlink;
 653         fid->pending_open = open;
 654         list_add_tail(&open->olist, &tlink_tcon(tlink)->pending_opens);
 655 }
 656
 657 void
 658 cifs_add_pending_open(struct cifs_fid *fid, struct tcon_link *tlink,
 659                       struct cifs_pending_open *open)
 660 {
 661         spin_lock(&tlink_tcon(tlink)->open_file_lock);
 662         cifs_add_pending_open_locked(fid, tlink, open);
 663         spin_unlock(&tlink_tcon(open->tlink)->open_file_lock);
 664 }
 665
 666 /*
 667  * Critical section which runs after acquiring deferred_lock.
 668  * As there is no reference count on cifs_deferred_close, pdclose
 669  * should not be used outside deferred_lock.
 670  */
 671 bool
 672 cifs_is_deferred_close(struct cifsFileInfo *cfile, struct cifs_deferred_close **pdclose)
 673 {
 674         struct cifs_deferred_close *dclose;
 675
 676         list_for_each_entry(dclose, &CIFS_I(d_inode(cfile->dentry))->deferred_closes, dlist) {
 677                 if ((dclose->netfid == cfile->fid.netfid) &&
 678                         (dclose->persistent_fid == cfile->fid.persistent_fid) &&
 679                         (dclose->volatile_fid == cfile->fid.volatile_fid)) {
 680                         *pdclose = dclose;
 681                         return true;
 682                 }
 683         }
 684         return false;
 685 }
 686
 687 /*
 688  * Critical section which runs after acquiring deferred_lock.
 689  */
 690 void
 691 cifs_add_deferred_close(struct cifsFileInfo *cfile, struct cifs_deferred_close *dclose)
 692 {
 693         bool is_deferred = false;
 694         struct cifs_deferred_close *pdclose;
 695
 696         is_deferred = cifs_is_deferred_close(cfile, &pdclose);
 697         if (is_deferred) {
 698                 kfree(dclose);
 699                 return;
 700         }
 701
 702         dclose->tlink = cfile->tlink;
 703         dclose->netfid = cfile->fid.netfid;
 704         dclose->persistent_fid = cfile->fid.persistent_fid;
 705         dclose->volatile_fid = cfile->fid.volatile_fid;
 706         list_add_tail(&dclose->dlist, &CIFS_I(d_inode(cfile->dentry))->deferred_closes);
 707 }
 708
 709 /*
 710  * Critical section which runs after acquiring deferred_lock.
 711  */
 712 void
 713 cifs_del_deferred_close(struct cifsFileInfo *cfile)
 714 {
 715         bool is_deferred = false;
 716         struct cifs_deferred_close *dclose;
 717
 718         is_deferred = cifs_is_deferred_close(cfile, &dclose);
 719         if (!is_deferred)
 720                 return;
 721         list_del(&dclose->dlist);
 722         kfree(dclose);
 723 }
 724
 725 void
 726 cifs_close_deferred_file(struct cifsInodeInfo *cifs_inode)
 727 {
 728         struct cifsFileInfo *cfile = NULL;
 729         struct file_list *tmp_list, *tmp_next_list;
 730         struct list_head file_head;
 731
 732         if (cifs_inode == NULL)
 733                 return;
 734
 735         INIT_LIST_HEAD(&file_head);
 736         spin_lock(&cifs_inode->open_file_lock);
 737         list_for_each_entry(cfile, &cifs_inode->openFileList, flist) {
 738                 if (delayed_work_pending(&cfile->deferred)) {
 739                         if (cancel_delayed_work(&cfile->deferred)) {
 740                                 tmp_list = kmalloc(sizeof(struct file_list), GFP_ATOMIC);
 741                                 if (tmp_list == NULL)
 742                                         break;
 743                                 tmp_list->cfile = cfile;
 744                                 list_add_tail(&tmp_list->list, &file_head);
 745                         }
 746                 }
 747         }
 748         spin_unlock(&cifs_inode->open_file_lock);
 749
 750         list_for_each_entry_safe(tmp_list, tmp_next_list, &file_head, list) {
 751                 _cifsFileInfo_put(tmp_list->cfile, true, false);
 752                 list_del(&tmp_list->list);
 753                 kfree(tmp_list);
 754         }
 755 }
 756
 757 void
 758 cifs_close_all_deferred_files(struct cifs_tcon *tcon)
 759 {
 760         struct cifsFileInfo *cfile;
 761         struct file_list *tmp_list, *tmp_next_list;
 762         struct list_head file_head;
 763
 764         INIT_LIST_HEAD(&file_head);
 765         spin_lock(&tcon->open_file_lock);
 766         list_for_each_entry(cfile, &tcon->openFileList, tlist) {
 767                 if (delayed_work_pending(&cfile->deferred)) {
 768                         if (cancel_delayed_work(&cfile->deferred)) {
 769                                 tmp_list = kmalloc(sizeof(struct file_list), GFP_ATOMIC);
 770                                 if (tmp_list == NULL)
 771                                         break;
 772                                 tmp_list->cfile = cfile;
 773                                 list_add_tail(&tmp_list->list, &file_head);
 774                         }
 775                 }
 776         }
 777         spin_unlock(&tcon->open_file_lock);
 778
 779         list_for_each_entry_safe(tmp_list, tmp_next_list, &file_head, list) {
 780                 _cifsFileInfo_put(tmp_list->cfile, true, false);
 781                 list_del(&tmp_list->list);
 782                 kfree(tmp_list);
 783         }
 784 }
 785 void
 786 cifs_close_deferred_file_under_dentry(struct cifs_tcon *tcon, const char *path)
 787 {
 788         struct cifsFileInfo *cfile;
 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_entry(cfile, &tcon->openFileList, tlist) {
 798                 full_path = build_path_from_dentry(cfile->dentry, page);
 799                 if (strstr(full_path, path)) {
 800                         if (delayed_work_pending(&cfile->deferred)) {
 801                                 if (cancel_delayed_work(&cfile->deferred)) {
 802                                         tmp_list = kmalloc(sizeof(struct file_list), GFP_ATOMIC);
 803                                         if (tmp_list == NULL)
 804                                                 break;
 805                                         tmp_list->cfile = cfile;
 806                                         list_add_tail(&tmp_list->list, &file_head);
 807                                 }
 808                         }
 809                 }
 810         }
 811         spin_unlock(&tcon->open_file_lock);
 812
 813         list_for_each_entry_safe(tmp_list, tmp_next_list, &file_head, list) {
 814                 _cifsFileInfo_put(tmp_list->cfile, true, false);
 815                 list_del(&tmp_list->list);
 816                 kfree(tmp_list);
 817         }
 818         free_dentry_path(page);
 819 }
 820
 821 /* parses DFS refferal V3 structure
 822  * caller is responsible for freeing target_nodes
 823  * returns:
 824  * - on success - 0
 825  * - on failure - errno
 826  */
 827 int
 828 parse_dfs_referrals(struct get_dfs_referral_rsp *rsp, u32 rsp_size,
 829                     unsigned int *num_of_nodes,
 830                     struct dfs_info3_param **target_nodes,
 831                     const struct nls_table *nls_codepage, int remap,
 832                     const char *searchName, bool is_unicode)
 833 {
 834         int i, rc = 0;
 835         char *data_end;
 836         struct dfs_referral_level_3 *ref;
 837
 838         *num_of_nodes = le16_to_cpu(rsp->NumberOfReferrals);
 839
 840         if (*num_of_nodes < 1) {
 841                 cifs_dbg(VFS, "num_referrals: must be at least > 0, but we get num_referrals = %d\n",
 842                          *num_of_nodes);
 843                 rc = -EINVAL;
 844                 goto parse_DFS_referrals_exit;
 845         }
 846
 847         ref = (struct dfs_referral_level_3 *) &(rsp->referrals);
 848         if (ref->VersionNumber != cpu_to_le16(3)) {
 849                 cifs_dbg(VFS, "Referrals of V%d version are not supported, should be V3\n",
 850                          le16_to_cpu(ref->VersionNumber));
 851                 rc = -EINVAL;
 852                 goto parse_DFS_referrals_exit;
 853         }
 854
 855         /* get the upper boundary of the resp buffer */
 856         data_end = (char *)rsp + rsp_size;
 857
 858         cifs_dbg(FYI, "num_referrals: %d dfs flags: 0x%x ...\n",
 859                  *num_of_nodes, le32_to_cpu(rsp->DFSFlags));
 860
 861         *target_nodes = kcalloc(*num_of_nodes, sizeof(struct dfs_info3_param),
 862                                 GFP_KERNEL);
 863         if (*target_nodes == NULL) {
 864                 rc = -ENOMEM;
 865                 goto parse_DFS_referrals_exit;
 866         }
 867
 868         /* collect necessary data from referrals */
 869         for (i = 0; i < *num_of_nodes; i++) {
 870                 char *temp;
 871                 int max_len;
 872                 struct dfs_info3_param *node = (*target_nodes)+i;
 873
 874                 node->flags = le32_to_cpu(rsp->DFSFlags);
 875                 if (is_unicode) {
 876                         __le16 *tmp = kmalloc(strlen(searchName)*2 + 2,
 877                                                 GFP_KERNEL);
 878                         if (tmp == NULL) {
 879                                 rc = -ENOMEM;
 880                                 goto parse_DFS_referrals_exit;
 881                         }
 882                         cifsConvertToUTF16((__le16 *) tmp, searchName,
 883                                            PATH_MAX, nls_codepage, remap);
 884                         node->path_consumed = cifs_utf16_bytes(tmp,
 885                                         le16_to_cpu(rsp->PathConsumed),
 886                                         nls_codepage);
 887                         kfree(tmp);
 888                 } else
 889                         node->path_consumed = le16_to_cpu(rsp->PathConsumed);
 890
 891                 node->server_type = le16_to_cpu(ref->ServerType);
 892                 node->ref_flag = le16_to_cpu(ref->ReferralEntryFlags);
 893
 894                 /* copy DfsPath */
 895                 temp = (char *)ref + le16_to_cpu(ref->DfsPathOffset);
 896                 max_len = data_end - temp;
 897                 node->path_name = cifs_strndup_from_utf16(temp, max_len,
 898                                                 is_unicode, nls_codepage);
 899                 if (!node->path_name) {
 900                         rc = -ENOMEM;
 901                         goto parse_DFS_referrals_exit;
 902                 }
 903
 904                 /* copy link target UNC */
 905                 temp = (char *)ref + le16_to_cpu(ref->NetworkAddressOffset);
 906                 max_len = data_end - temp;
 907                 node->node_name = cifs_strndup_from_utf16(temp, max_len,
 908                                                 is_unicode, nls_codepage);
 909                 if (!node->node_name) {
 910                         rc = -ENOMEM;
 911                         goto parse_DFS_referrals_exit;
 912                 }
 913
 914                 node->ttl = le32_to_cpu(ref->TimeToLive);
 915
 916                 ref++;
 917         }
 918
 919 parse_DFS_referrals_exit:
 920         if (rc) {
 921                 free_dfs_info_array(*target_nodes, *num_of_nodes);
 922                 *target_nodes = NULL;
 923                 *num_of_nodes = 0;
 924         }
 925         return rc;
 926 }
 927
 928 struct cifs_aio_ctx *
 929 cifs_aio_ctx_alloc(void)
 930 {
 931         struct cifs_aio_ctx *ctx;
 932
 933         /*
 934          * Must use kzalloc to initialize ctx->bv to NULL and ctx->direct_io
 935          * to false so that we know when we have to unreference pages within
 936          * cifs_aio_ctx_release()
 937          */
 938         ctx = kzalloc(sizeof(struct cifs_aio_ctx), GFP_KERNEL);
 939         if (!ctx)
 940                 return NULL;
 941
 942         INIT_LIST_HEAD(&ctx->list);
 943         mutex_init(&ctx->aio_mutex);
 944         init_completion(&ctx->done);
 945         kref_init(&ctx->refcount);
 946         return ctx;
 947 }
 948
 949 void
 950 cifs_aio_ctx_release(struct kref *refcount)
 951 {
 952         struct cifs_aio_ctx *ctx = container_of(refcount,
 953                                         struct cifs_aio_ctx, refcount);
 954
 955         cifsFileInfo_put(ctx->cfile);
 956
 957         /*
 958          * ctx->bv is only set if setup_aio_ctx_iter() was call successfuly
 959          * which means that iov_iter_get_pages() was a success and thus that
 960          * we have taken reference on pages.
 961          */
 962         if (ctx->bv) {
 963                 unsigned i;
 964
 965                 for (i = 0; i < ctx->npages; i++) {
 966                         if (ctx->should_dirty)
 967                                 set_page_dirty(ctx->bv[i].bv_page);
 968                         put_page(ctx->bv[i].bv_page);
 969                 }
 970                 kvfree(ctx->bv);
 971         }
 972
 973         kfree(ctx);
 974 }
 975
 976 #define CIFS_AIO_KMALLOC_LIMIT (1024 * 1024)
 977
 978 int
 979 setup_aio_ctx_iter(struct cifs_aio_ctx *ctx, struct iov_iter *iter, int rw)
 980 {
 981         ssize_t rc;
 982         unsigned int cur_npages;
 983         unsigned int npages = 0;
 984         unsigned int i;
 985         size_t len;
 986         size_t count = iov_iter_count(iter);
 987         unsigned int saved_len;
 988         size_t start;
 989         unsigned int max_pages = iov_iter_npages(iter, INT_MAX);
 990         struct page **pages = NULL;
 991         struct bio_vec *bv = NULL;
 992
 993         if (iov_iter_is_kvec(iter)) {
 994                 memcpy(&ctx->iter, iter, sizeof(*iter));
 995                 ctx->len = count;
 996                 iov_iter_advance(iter, count);
 997                 return 0;
 998         }
 999
1000         if (array_size(max_pages, sizeof(*bv)) <= CIFS_AIO_KMALLOC_LIMIT)
1001                 bv = kmalloc_array(max_pages, sizeof(*bv), GFP_KERNEL);
1002
1003         if (!bv) {
1004                 bv = vmalloc(array_size(max_pages, sizeof(*bv)));
1005                 if (!bv)
1006                         return -ENOMEM;
1007         }
1008
1009         if (array_size(max_pages, sizeof(*pages)) <= CIFS_AIO_KMALLOC_LIMIT)
1010                 pages = kmalloc_array(max_pages, sizeof(*pages), GFP_KERNEL);
1011
1012         if (!pages) {
1013                 pages = vmalloc(array_size(max_pages, sizeof(*pages)));
1014                 if (!pages) {
1015                         kvfree(bv);
1016                         return -ENOMEM;
1017                 }
1018         }
1019
1020         saved_len = count;
1021
1022         while (count && npages < max_pages) {
1023                 rc = iov_iter_get_pages2(iter, pages, count, max_pages, &start);
1024                 if (rc < 0) {
1025                         cifs_dbg(VFS, "Couldn't get user pages (rc=%zd)\n", rc);
1026                         break;
1027                 }
1028
1029                 if (rc > count) {
1030                         cifs_dbg(VFS, "get pages rc=%zd more than %zu\n", rc,
1031                                  count);
1032                         break;
1033                 }
1034
1035                 count -= rc;
1036                 rc += start;
1037                 cur_npages = DIV_ROUND_UP(rc, PAGE_SIZE);
1038
1039                 if (npages + cur_npages > max_pages) {
1040                         cifs_dbg(VFS, "out of vec array capacity (%u vs %u)\n",
1041                                  npages + cur_npages, max_pages);
1042                         break;
1043                 }
1044
1045                 for (i = 0; i < cur_npages; i++) {
1046                         len = rc > PAGE_SIZE ? PAGE_SIZE : rc;
1047                         bv[npages + i].bv_page = pages[i];
1048                         bv[npages + i].bv_offset = start;
1049                         bv[npages + i].bv_len = len - start;
1050                         rc -= len;
1051                         start = 0;
1052                 }
1053
1054                 npages += cur_npages;
1055         }
1056
1057         kvfree(pages);
1058         ctx->bv = bv;
1059         ctx->len = saved_len - count;
1060         ctx->npages = npages;
1061         iov_iter_bvec(&ctx->iter, rw, ctx->bv, npages, ctx->len);
1062         return 0;
1063 }
1064
1065 /**
1066  * cifs_alloc_hash - allocate hash and hash context together
1067  * @name: The name of the crypto hash algo
1068  * @shash: Where to put the pointer to the hash algo
1069  * @sdesc: Where to put the pointer to the hash descriptor
1070  *
1071  * The caller has to make sure @sdesc is initialized to either NULL or
1072  * a valid context. Both can be freed via cifs_free_hash().
1073  */
1074 int
1075 cifs_alloc_hash(const char *name,
1076                 struct crypto_shash **shash, struct sdesc **sdesc)
1077 {
1078         int rc = 0;
1079         size_t size;
1080
1081         if (*sdesc != NULL)
1082                 return 0;
1083
1084         *shash = crypto_alloc_shash(name, 0, 0);
1085         if (IS_ERR(*shash)) {
1086                 cifs_dbg(VFS, "Could not allocate crypto %s\n", name);
1087                 rc = PTR_ERR(*shash);
1088                 *shash = NULL;
1089                 *sdesc = NULL;
1090                 return rc;
1091         }
1092
1093         size = sizeof(struct shash_desc) + crypto_shash_descsize(*shash);
1094         *sdesc = kmalloc(size, GFP_KERNEL);
1095         if (*sdesc == NULL) {
1096                 cifs_dbg(VFS, "no memory left to allocate crypto %s\n", name);
1097                 crypto_free_shash(*shash);
1098                 *shash = NULL;
1099                 return -ENOMEM;
1100         }
1101
1102         (*sdesc)->shash.tfm = *shash;
1103         return 0;
1104 }
1105
1106 /**
1107  * cifs_free_hash - free hash and hash context together
1108  * @shash: Where to find the pointer to the hash algo
1109  * @sdesc: Where to find the pointer to the hash descriptor
1110  *
1111  * Freeing a NULL hash or context is safe.
1112  */
1113 void
1114 cifs_free_hash(struct crypto_shash **shash, struct sdesc **sdesc)
1115 {
1116         kfree(*sdesc);
1117         *sdesc = NULL;
1118         if (*shash)
1119                 crypto_free_shash(*shash);
1120         *shash = NULL;
1121 }
1122
1123 /**
1124  * rqst_page_get_length - obtain the length and offset for a page in smb_rqst
1125  * @rqst: The request descriptor
1126  * @page: The index of the page to query
1127  * @len: Where to store the length for this page:
1128  * @offset: Where to store the offset for this page
1129  */
1130 void rqst_page_get_length(struct smb_rqst *rqst, unsigned int page,
1131                                 unsigned int *len, unsigned int *offset)
1132 {
1133         *len = rqst->rq_pagesz;
1134         *offset = (page == 0) ? rqst->rq_offset : 0;
1135
1136         if (rqst->rq_npages == 1 || page == rqst->rq_npages-1)
1137                 *len = rqst->rq_tailsz;
1138         else if (page == 0)
1139                 *len = rqst->rq_pagesz - rqst->rq_offset;
1140 }
1141
1142 void extract_unc_hostname(const char *unc, const char **h, size_t *len)
1143 {
1144         const char *end;
1145
1146         /* skip initial slashes */
1147         while (*unc && (*unc == '\\' || *unc == '/'))
1148                 unc++;
1149
1150         end = unc;
1151
1152         while (*end && !(*end == '\\' || *end == '/'))
1153                 end++;
1154
1155         *h = unc;
1156         *len = end - unc;
1157 }
1158
1159 /**
1160  * copy_path_name - copy src path to dst, possibly truncating
1161  * @dst: The destination buffer
1162  * @src: The source name
1163  *
1164  * returns number of bytes written (including trailing nul)
1165  */
1166 int copy_path_name(char *dst, const char *src)
1167 {
1168         int name_len;
1169
1170         /*
1171          * PATH_MAX includes nul, so if strlen(src) >= PATH_MAX it
1172          * will truncate and strlen(dst) will be PATH_MAX-1
1173          */
1174         name_len = strscpy(dst, src, PATH_MAX);
1175         if (WARN_ON_ONCE(name_len < 0))
1176                 name_len = PATH_MAX-1;
1177
1178         /* we count the trailing nul */
1179         name_len++;
1180         return name_len;
1181 }
1182
1183 struct super_cb_data {
1184         void *data;
1185         struct super_block *sb;
1186 };
1187
1188 static void tcp_super_cb(struct super_block *sb, void *arg)
1189 {
1190         struct super_cb_data *sd = arg;
1191         struct TCP_Server_Info *server = sd->data;
1192         struct cifs_sb_info *cifs_sb;
1193         struct cifs_tcon *tcon;
1194
1195         if (sd->sb)
1196                 return;
1197
1198         cifs_sb = CIFS_SB(sb);
1199         tcon = cifs_sb_master_tcon(cifs_sb);
1200         if (tcon->ses->server == server)
1201                 sd->sb = sb;
1202 }
1203
1204 static struct super_block *__cifs_get_super(void (*f)(struct super_block *, void *),
1205                                             void *data)
1206 {
1207         struct super_cb_data sd = {
1208                 .data = data,
1209                 .sb = NULL,
1210         };
1211         struct file_system_type **fs_type = (struct file_system_type *[]) {
1212                 &cifs_fs_type, &smb3_fs_type, NULL,
1213         };
1214
1215         for (; *fs_type; fs_type++) {
1216                 iterate_supers_type(*fs_type, f, &sd);
1217                 if (sd.sb) {
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         return ERR_PTR(-EINVAL);
1228 }
1229
1230 static void __cifs_put_super(struct super_block *sb)
1231 {
1232         if (!IS_ERR_OR_NULL(sb))
1233                 cifs_sb_deactive(sb);
1234 }
1235
1236 struct super_block *cifs_get_tcp_super(struct TCP_Server_Info *server)
1237 {
1238         return __cifs_get_super(tcp_super_cb, server);
1239 }
1240
1241 void cifs_put_tcp_super(struct super_block *sb)
1242 {
1243         __cifs_put_super(sb);
1244 }
1245
1246 #ifdef CONFIG_CIFS_DFS_UPCALL
1247 int match_target_ip(struct TCP_Server_Info *server,
1248                     const char *share, size_t share_len,
1249                     bool *result)
1250 {
1251         int rc;
1252         char *target, *tip = NULL;
1253         struct sockaddr tipaddr;
1254
1255         *result = false;
1256
1257         target = kzalloc(share_len + 3, GFP_KERNEL);
1258         if (!target) {
1259                 rc = -ENOMEM;
1260                 goto out;
1261         }
1262
1263         scnprintf(target, share_len + 3, "\\\\%.*s", (int)share_len, share);
1264
1265         cifs_dbg(FYI, "%s: target name: %s\n", __func__, target + 2);
1266
1267         rc = dns_resolve_server_name_to_ip(target, &tip, NULL);
1268         if (rc < 0)
1269                 goto out;
1270
1271         cifs_dbg(FYI, "%s: target ip: %s\n", __func__, tip);
1272
1273         if (!cifs_convert_address(&tipaddr, tip, strlen(tip))) {
1274                 cifs_dbg(VFS, "%s: failed to convert target ip address\n",
1275                          __func__);
1276                 rc = -EINVAL;
1277                 goto out;
1278         }
1279
1280         *result = cifs_match_ipaddr((struct sockaddr *)&server->dstaddr,
1281                                     &tipaddr);
1282         cifs_dbg(FYI, "%s: ip addresses match: %u\n", __func__, *result);
1283         rc = 0;
1284
1285 out:
1286         kfree(target);
1287         kfree(tip);
1288
1289         return rc;
1290 }
1291
1292 int cifs_update_super_prepath(struct cifs_sb_info *cifs_sb, char *prefix)
1293 {
1294         kfree(cifs_sb->prepath);
1295
1296         if (prefix && *prefix) {
1297                 cifs_sb->prepath = kstrdup(prefix, GFP_ATOMIC);
1298                 if (!cifs_sb->prepath)
1299                         return -ENOMEM;
1300
1301                 convert_delimiter(cifs_sb->prepath, CIFS_DIR_SEP(cifs_sb));
1302         } else
1303                 cifs_sb->prepath = NULL;
1304
1305         cifs_sb->mnt_cifs_flags |= CIFS_MOUNT_USE_PREFIX_PATH;
1306         return 0;
1307 }
1308
1309 /** cifs_dfs_query_info_nonascii_quirk
1310  * Handle weird Windows SMB server behaviour. It responds with
1311  * STATUS_OBJECT_NAME_INVALID code to SMB2 QUERY_INFO request
1312  * for "\<server>\<dfsname>\<linkpath>" DFS reference,
1313  * where <dfsname> contains non-ASCII unicode symbols.
1314  *
1315  * Check such DFS reference.
1316  */
1317 int cifs_dfs_query_info_nonascii_quirk(const unsigned int xid,
1318                                        struct cifs_tcon *tcon,
1319                                        struct cifs_sb_info *cifs_sb,
1320                                        const char *linkpath)
1321 {
1322         char *treename, *dfspath, sep;
1323         int treenamelen, linkpathlen, rc;
1324
1325         treename = tcon->treeName;
1326         /* MS-DFSC: All paths in REQ_GET_DFS_REFERRAL and RESP_GET_DFS_REFERRAL
1327          * messages MUST be encoded with exactly one leading backslash, not two
1328          * leading backslashes.
1329          */
1330         sep = CIFS_DIR_SEP(cifs_sb);
1331         if (treename[0] == sep && treename[1] == sep)
1332                 treename++;
1333         linkpathlen = strlen(linkpath);
1334         treenamelen = strnlen(treename, MAX_TREE_SIZE + 1);
1335         dfspath = kzalloc(treenamelen + linkpathlen + 1, GFP_KERNEL);
1336         if (!dfspath)
1337                 return -ENOMEM;
1338         if (treenamelen)
1339                 memcpy(dfspath, treename, treenamelen);
1340         memcpy(dfspath + treenamelen, linkpath, linkpathlen);
1341         rc = dfs_cache_find(xid, tcon->ses, cifs_sb->local_nls,
1342                             cifs_remap(cifs_sb), dfspath, NULL, NULL);
1343         if (rc == 0) {
1344                 cifs_dbg(FYI, "DFS ref '%s' is found, emulate -EREMOTE\n",
1345                          dfspath);
1346                 rc = -EREMOTE;
1347         } else {
1348                 cifs_dbg(FYI, "%s: dfs_cache_find returned %d\n", __func__, rc);
1349         }
1350         kfree(dfspath);
1351         return rc;
1352 }
1353 #endif