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         }
  79         return ret_buf;
  80 }
  81
  82 void
  83 sesInfoFree(struct cifs_ses *buf_to_free)
  84 {
  85         if (buf_to_free == NULL) {
  86                 cifs_dbg(FYI, "Null buffer passed to sesInfoFree\n");
  87                 return;
  88         }
  89
  90         atomic_dec(&sesInfoAllocCount);
  91         kfree(buf_to_free->serverOS);
  92         kfree(buf_to_free->serverDomain);
  93         kfree(buf_to_free->serverNOS);
  94         kfree_sensitive(buf_to_free->password);
  95         kfree(buf_to_free->user_name);
  96         kfree(buf_to_free->domainName);
  97         kfree_sensitive(buf_to_free->auth_key.response);
  98         kfree(buf_to_free->iface_list);
  99         kfree_sensitive(buf_to_free);
 100 }
 101
 102 struct cifs_tcon *
 103 tconInfoAlloc(void)
 104 {
 105         struct cifs_tcon *ret_buf;
 106
 107         ret_buf = kzalloc(sizeof(*ret_buf), GFP_KERNEL);
 108         if (!ret_buf)
 109                 return NULL;
 110         ret_buf->crfid.fid = kzalloc(sizeof(*ret_buf->crfid.fid), GFP_KERNEL);
 111         if (!ret_buf->crfid.fid) {
 112                 kfree(ret_buf);
 113                 return NULL;
 114         }
 115
 116         atomic_inc(&tconInfoAllocCount);
 117         ret_buf->tidStatus = CifsNew;
 118         ++ret_buf->tc_count;
 119         INIT_LIST_HEAD(&ret_buf->openFileList);
 120         INIT_LIST_HEAD(&ret_buf->tcon_list);
 121         spin_lock_init(&ret_buf->open_file_lock);
 122         mutex_init(&ret_buf->crfid.fid_mutex);
 123         spin_lock_init(&ret_buf->stat_lock);
 124         atomic_set(&ret_buf->num_local_opens, 0);
 125         atomic_set(&ret_buf->num_remote_opens, 0);
 126
 127         return ret_buf;
 128 }
 129
 130 void
 131 tconInfoFree(struct cifs_tcon *buf_to_free)
 132 {
 133         if (buf_to_free == NULL) {
 134                 cifs_dbg(FYI, "Null buffer passed to tconInfoFree\n");
 135                 return;
 136         }
 137         atomic_dec(&tconInfoAllocCount);
 138         kfree(buf_to_free->nativeFileSystem);
 139         kfree_sensitive(buf_to_free->password);
 140         kfree(buf_to_free->crfid.fid);
 141 #ifdef CONFIG_CIFS_DFS_UPCALL
 142         kfree(buf_to_free->dfs_path);
 143 #endif
 144         kfree(buf_to_free);
 145 }
 146
 147 struct smb_hdr *
 148 cifs_buf_get(void)
 149 {
 150         struct smb_hdr *ret_buf = NULL;
 151         /*
 152          * SMB2 header is bigger than CIFS one - no problems to clean some
 153          * more bytes for CIFS.
 154          */
 155         size_t buf_size = sizeof(struct smb2_sync_hdr);
 156
 157         /*
 158          * We could use negotiated size instead of max_msgsize -
 159          * but it may be more efficient to always alloc same size
 160          * albeit slightly larger than necessary and maxbuffersize
 161          * defaults to this and can not be bigger.
 162          */
 163         ret_buf = mempool_alloc(cifs_req_poolp, GFP_NOFS);
 164
 165         /* clear the first few header bytes */
 166         /* for most paths, more is cleared in header_assemble */
 167         memset(ret_buf, 0, buf_size + 3);
 168         atomic_inc(&bufAllocCount);
 169 #ifdef CONFIG_CIFS_STATS2
 170         atomic_inc(&totBufAllocCount);
 171 #endif /* CONFIG_CIFS_STATS2 */
 172
 173         return ret_buf;
 174 }
 175
 176 void
 177 cifs_buf_release(void *buf_to_free)
 178 {
 179         if (buf_to_free == NULL) {
 180                 /* cifs_dbg(FYI, "Null buffer passed to cifs_buf_release\n");*/
 181                 return;
 182         }
 183         mempool_free(buf_to_free, cifs_req_poolp);
 184
 185         atomic_dec(&bufAllocCount);
 186         return;
 187 }
 188
 189 struct smb_hdr *
 190 cifs_small_buf_get(void)
 191 {
 192         struct smb_hdr *ret_buf = NULL;
 193
 194 /* We could use negotiated size instead of max_msgsize -
 195    but it may be more efficient to always alloc same size
 196    albeit slightly larger than necessary and maxbuffersize
 197    defaults to this and can not be bigger */
 198         ret_buf = mempool_alloc(cifs_sm_req_poolp, GFP_NOFS);
 199         /* No need to clear memory here, cleared in header assemble */
 200         /*      memset(ret_buf, 0, sizeof(struct smb_hdr) + 27);*/
 201         atomic_inc(&smBufAllocCount);
 202 #ifdef CONFIG_CIFS_STATS2
 203         atomic_inc(&totSmBufAllocCount);
 204 #endif /* CONFIG_CIFS_STATS2 */
 205
 206         return ret_buf;
 207 }
 208
 209 void
 210 cifs_small_buf_release(void *buf_to_free)
 211 {
 212
 213         if (buf_to_free == NULL) {
 214                 cifs_dbg(FYI, "Null buffer passed to cifs_small_buf_release\n");
 215                 return;
 216         }
 217         mempool_free(buf_to_free, cifs_sm_req_poolp);
 218
 219         atomic_dec(&smBufAllocCount);
 220         return;
 221 }
 222
 223 void
 224 free_rsp_buf(int resp_buftype, void *rsp)
 225 {
 226         if (resp_buftype == CIFS_SMALL_BUFFER)
 227                 cifs_small_buf_release(rsp);
 228         else if (resp_buftype == CIFS_LARGE_BUFFER)
 229                 cifs_buf_release(rsp);
 230 }
 231
 232 /* NB: MID can not be set if treeCon not passed in, in that
 233    case it is responsbility of caller to set the mid */
 234 void
 235 header_assemble(struct smb_hdr *buffer, char smb_command /* command */ ,
 236                 const struct cifs_tcon *treeCon, int word_count
 237                 /* length of fixed section (word count) in two byte units  */)
 238 {
 239         char *temp = (char *) buffer;
 240
 241         memset(temp, 0, 256); /* bigger than MAX_CIFS_HDR_SIZE */
 242
 243         buffer->smb_buf_length = cpu_to_be32(
 244             (2 * word_count) + sizeof(struct smb_hdr) -
 245             4 /*  RFC 1001 length field does not count */  +
 246             2 /* for bcc field itself */) ;
 247
 248         buffer->Protocol[0] = 0xFF;
 249         buffer->Protocol[1] = 'S';
 250         buffer->Protocol[2] = 'M';
 251         buffer->Protocol[3] = 'B';
 252         buffer->Command = smb_command;
 253         buffer->Flags = 0x00;   /* case sensitive */
 254         buffer->Flags2 = SMBFLG2_KNOWS_LONG_NAMES;
 255         buffer->Pid = cpu_to_le16((__u16)current->tgid);
 256         buffer->PidHigh = cpu_to_le16((__u16)(current->tgid >> 16));
 257         if (treeCon) {
 258                 buffer->Tid = treeCon->tid;
 259                 if (treeCon->ses) {
 260                         if (treeCon->ses->capabilities & CAP_UNICODE)
 261                                 buffer->Flags2 |= SMBFLG2_UNICODE;
 262                         if (treeCon->ses->capabilities & CAP_STATUS32)
 263                                 buffer->Flags2 |= SMBFLG2_ERR_STATUS;
 264
 265                         /* Uid is not converted */
 266                         buffer->Uid = treeCon->ses->Suid;
 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  *
 594  * This function is called from the demultiplex thread when it
 595  * receives an oplock break for @cfile.
 596  *
 597  * Assumes the tcon->open_file_lock is held.
 598  * Assumes cfile->file_info_lock is NOT held.
 599  */
 600 void cifs_queue_oplock_break(struct cifsFileInfo *cfile)
 601 {
 602         /*
 603          * Bump the handle refcount now while we hold the
 604          * open_file_lock to enforce the validity of it for the oplock
 605          * break handler. The matching put is done at the end of the
 606          * handler.
 607          */
 608         cifsFileInfo_get(cfile);
 609
 610         queue_work(cifsoplockd_wq, &cfile->oplock_break);
 611 }
 612
 613 void cifs_done_oplock_break(struct cifsInodeInfo *cinode)
 614 {
 615         clear_bit(CIFS_INODE_PENDING_OPLOCK_BREAK, &cinode->flags);
 616         wake_up_bit(&cinode->flags, CIFS_INODE_PENDING_OPLOCK_BREAK);
 617 }
 618
 619 bool
 620 backup_cred(struct cifs_sb_info *cifs_sb)
 621 {
 622         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_BACKUPUID) {
 623                 if (uid_eq(cifs_sb->ctx->backupuid, current_fsuid()))
 624                         return true;
 625         }
 626         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_BACKUPGID) {
 627                 if (in_group_p(cifs_sb->ctx->backupgid))
 628                         return true;
 629         }
 630
 631         return false;
 632 }
 633
 634 void
 635 cifs_del_pending_open(struct cifs_pending_open *open)
 636 {
 637         spin_lock(&tlink_tcon(open->tlink)->open_file_lock);
 638         list_del(&open->olist);
 639         spin_unlock(&tlink_tcon(open->tlink)->open_file_lock);
 640 }
 641
 642 void
 643 cifs_add_pending_open_locked(struct cifs_fid *fid, struct tcon_link *tlink,
 644                              struct cifs_pending_open *open)
 645 {
 646         memcpy(open->lease_key, fid->lease_key, SMB2_LEASE_KEY_SIZE);
 647         open->oplock = CIFS_OPLOCK_NO_CHANGE;
 648         open->tlink = tlink;
 649         fid->pending_open = open;
 650         list_add_tail(&open->olist, &tlink_tcon(tlink)->pending_opens);
 651 }
 652
 653 void
 654 cifs_add_pending_open(struct cifs_fid *fid, struct tcon_link *tlink,
 655                       struct cifs_pending_open *open)
 656 {
 657         spin_lock(&tlink_tcon(tlink)->open_file_lock);
 658         cifs_add_pending_open_locked(fid, tlink, open);
 659         spin_unlock(&tlink_tcon(open->tlink)->open_file_lock);
 660 }
 661
 662 /*
 663  * Critical section which runs after acquiring deferred_lock.
 664  * As there is no reference count on cifs_deferred_close, pdclose
 665  * should not be used outside deferred_lock.
 666  */
 667 bool
 668 cifs_is_deferred_close(struct cifsFileInfo *cfile, struct cifs_deferred_close **pdclose)
 669 {
 670         struct cifs_deferred_close *dclose;
 671
 672         list_for_each_entry(dclose, &CIFS_I(d_inode(cfile->dentry))->deferred_closes, dlist) {
 673                 if ((dclose->netfid == cfile->fid.netfid) &&
 674                         (dclose->persistent_fid == cfile->fid.persistent_fid) &&
 675                         (dclose->volatile_fid == cfile->fid.volatile_fid)) {
 676                         *pdclose = dclose;
 677                         return true;
 678                 }
 679         }
 680         return false;
 681 }
 682
 683 /*
 684  * Critical section which runs after acquiring deferred_lock.
 685  */
 686 void
 687 cifs_add_deferred_close(struct cifsFileInfo *cfile, struct cifs_deferred_close *dclose)
 688 {
 689         bool is_deferred = false;
 690         struct cifs_deferred_close *pdclose;
 691
 692         is_deferred = cifs_is_deferred_close(cfile, &pdclose);
 693         if (is_deferred) {
 694                 kfree(dclose);
 695                 return;
 696         }
 697
 698         dclose->tlink = cfile->tlink;
 699         dclose->netfid = cfile->fid.netfid;
 700         dclose->persistent_fid = cfile->fid.persistent_fid;
 701         dclose->volatile_fid = cfile->fid.volatile_fid;
 702         list_add_tail(&dclose->dlist, &CIFS_I(d_inode(cfile->dentry))->deferred_closes);
 703 }
 704
 705 /*
 706  * Critical section which runs after acquiring deferred_lock.
 707  */
 708 void
 709 cifs_del_deferred_close(struct cifsFileInfo *cfile)
 710 {
 711         bool is_deferred = false;
 712         struct cifs_deferred_close *dclose;
 713
 714         is_deferred = cifs_is_deferred_close(cfile, &dclose);
 715         if (!is_deferred)
 716                 return;
 717         list_del(&dclose->dlist);
 718         kfree(dclose);
 719 }
 720
 721 void
 722 cifs_close_deferred_file(struct cifsInodeInfo *cifs_inode)
 723 {
 724         struct cifsFileInfo *cfile = NULL;
 725         struct file_list *tmp_list, *tmp_next_list;
 726         struct list_head file_head;
 727
 728         if (cifs_inode == NULL)
 729                 return;
 730
 731         INIT_LIST_HEAD(&file_head);
 732         spin_lock(&cifs_inode->open_file_lock);
 733         list_for_each_entry(cfile, &cifs_inode->openFileList, flist) {
 734                 if (delayed_work_pending(&cfile->deferred)) {
 735                         if (cancel_delayed_work(&cfile->deferred)) {
 736                                 tmp_list = kmalloc(sizeof(struct file_list), GFP_ATOMIC);
 737                                 if (tmp_list == NULL)
 738                                         break;
 739                                 tmp_list->cfile = cfile;
 740                                 list_add_tail(&tmp_list->list, &file_head);
 741                         }
 742                 }
 743         }
 744         spin_unlock(&cifs_inode->open_file_lock);
 745
 746         list_for_each_entry_safe(tmp_list, tmp_next_list, &file_head, list) {
 747                 _cifsFileInfo_put(tmp_list->cfile, true, false);
 748                 list_del(&tmp_list->list);
 749                 kfree(tmp_list);
 750         }
 751 }
 752
 753 void
 754 cifs_close_all_deferred_files(struct cifs_tcon *tcon)
 755 {
 756         struct cifsFileInfo *cfile;
 757         struct list_head *tmp;
 758         struct file_list *tmp_list, *tmp_next_list;
 759         struct list_head file_head;
 760
 761         INIT_LIST_HEAD(&file_head);
 762         spin_lock(&tcon->open_file_lock);
 763         list_for_each(tmp, &tcon->openFileList) {
 764                 cfile = list_entry(tmp, struct cifsFileInfo, tlist);
 765                 if (delayed_work_pending(&cfile->deferred)) {
 766                         if (cancel_delayed_work(&cfile->deferred)) {
 767                                 tmp_list = kmalloc(sizeof(struct file_list), GFP_ATOMIC);
 768                                 if (tmp_list == NULL)
 769                                         break;
 770                                 tmp_list->cfile = cfile;
 771                                 list_add_tail(&tmp_list->list, &file_head);
 772                         }
 773                 }
 774         }
 775         spin_unlock(&tcon->open_file_lock);
 776
 777         list_for_each_entry_safe(tmp_list, tmp_next_list, &file_head, list) {
 778                 _cifsFileInfo_put(tmp_list->cfile, true, false);
 779                 list_del(&tmp_list->list);
 780                 kfree(tmp_list);
 781         }
 782 }
 783 void
 784 cifs_close_deferred_file_under_dentry(struct cifs_tcon *tcon, const char *path)
 785 {
 786         struct cifsFileInfo *cfile;
 787         struct list_head *tmp;
 788         struct file_list *tmp_list, *tmp_next_list;
 789         struct list_head file_head;
 790         void *page;
 791         const char *full_path;
 792
 793         INIT_LIST_HEAD(&file_head);
 794         page = alloc_dentry_path();
 795         spin_lock(&tcon->open_file_lock);
 796         list_for_each(tmp, &tcon->openFileList) {
 797                 cfile = list_entry(tmp, struct cifsFileInfo, 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_pages(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                 iov_iter_advance(iter, rc);
1036                 count -= rc;
1037                 rc += start;
1038                 cur_npages = DIV_ROUND_UP(rc, PAGE_SIZE);
1039
1040                 if (npages + cur_npages > max_pages) {
1041                         cifs_dbg(VFS, "out of vec array capacity (%u vs %u)\n",
1042                                  npages + cur_npages, max_pages);
1043                         break;
1044                 }
1045
1046                 for (i = 0; i < cur_npages; i++) {
1047                         len = rc > PAGE_SIZE ? PAGE_SIZE : rc;
1048                         bv[npages + i].bv_page = pages[i];
1049                         bv[npages + i].bv_offset = start;
1050                         bv[npages + i].bv_len = len - start;
1051                         rc -= len;
1052                         start = 0;
1053                 }
1054
1055                 npages += cur_npages;
1056         }
1057
1058         kvfree(pages);
1059         ctx->bv = bv;
1060         ctx->len = saved_len - count;
1061         ctx->npages = npages;
1062         iov_iter_bvec(&ctx->iter, rw, ctx->bv, npages, ctx->len);
1063         return 0;
1064 }
1065
1066 /**
1067  * cifs_alloc_hash - allocate hash and hash context together
1068  *
1069  * The caller has to make sure @sdesc is initialized to either NULL or
1070  * a valid context. Both can be freed via cifs_free_hash().
1071  */
1072 int
1073 cifs_alloc_hash(const char *name,
1074                 struct crypto_shash **shash, struct sdesc **sdesc)
1075 {
1076         int rc = 0;
1077         size_t size;
1078
1079         if (*sdesc != NULL)
1080                 return 0;
1081
1082         *shash = crypto_alloc_shash(name, 0, 0);
1083         if (IS_ERR(*shash)) {
1084                 cifs_dbg(VFS, "Could not allocate crypto %s\n", name);
1085                 rc = PTR_ERR(*shash);
1086                 *shash = NULL;
1087                 *sdesc = NULL;
1088                 return rc;
1089         }
1090
1091         size = sizeof(struct shash_desc) + crypto_shash_descsize(*shash);
1092         *sdesc = kmalloc(size, GFP_KERNEL);
1093         if (*sdesc == NULL) {
1094                 cifs_dbg(VFS, "no memory left to allocate crypto %s\n", name);
1095                 crypto_free_shash(*shash);
1096                 *shash = NULL;
1097                 return -ENOMEM;
1098         }
1099
1100         (*sdesc)->shash.tfm = *shash;
1101         return 0;
1102 }
1103
1104 /**
1105  * cifs_free_hash - free hash and hash context together
1106  *
1107  * Freeing a NULL hash or context is safe.
1108  */
1109 void
1110 cifs_free_hash(struct crypto_shash **shash, struct sdesc **sdesc)
1111 {
1112         kfree(*sdesc);
1113         *sdesc = NULL;
1114         if (*shash)
1115                 crypto_free_shash(*shash);
1116         *shash = NULL;
1117 }
1118
1119 /**
1120  * rqst_page_get_length - obtain the length and offset for a page in smb_rqst
1121  * Input: rqst - a smb_rqst, page - a page index for rqst
1122  * Output: *len - the length for this page, *offset - the offset for this page
1123  */
1124 void rqst_page_get_length(struct smb_rqst *rqst, unsigned int page,
1125                                 unsigned int *len, unsigned int *offset)
1126 {
1127         *len = rqst->rq_pagesz;
1128         *offset = (page == 0) ? rqst->rq_offset : 0;
1129
1130         if (rqst->rq_npages == 1 || page == rqst->rq_npages-1)
1131                 *len = rqst->rq_tailsz;
1132         else if (page == 0)
1133                 *len = rqst->rq_pagesz - rqst->rq_offset;
1134 }
1135
1136 void extract_unc_hostname(const char *unc, const char **h, size_t *len)
1137 {
1138         const char *end;
1139
1140         /* skip initial slashes */
1141         while (*unc && (*unc == '\\' || *unc == '/'))
1142                 unc++;
1143
1144         end = unc;
1145
1146         while (*end && !(*end == '\\' || *end == '/'))
1147                 end++;
1148
1149         *h = unc;
1150         *len = end - unc;
1151 }
1152
1153 /**
1154  * copy_path_name - copy src path to dst, possibly truncating
1155  *
1156  * returns number of bytes written (including trailing nul)
1157  */
1158 int copy_path_name(char *dst, const char *src)
1159 {
1160         int name_len;
1161
1162         /*
1163          * PATH_MAX includes nul, so if strlen(src) >= PATH_MAX it
1164          * will truncate and strlen(dst) will be PATH_MAX-1
1165          */
1166         name_len = strscpy(dst, src, PATH_MAX);
1167         if (WARN_ON_ONCE(name_len < 0))
1168                 name_len = PATH_MAX-1;
1169
1170         /* we count the trailing nul */
1171         name_len++;
1172         return name_len;
1173 }
1174
1175 struct super_cb_data {
1176         void *data;
1177         struct super_block *sb;
1178 };
1179
1180 static void tcp_super_cb(struct super_block *sb, void *arg)
1181 {
1182         struct super_cb_data *sd = arg;
1183         struct TCP_Server_Info *server = sd->data;
1184         struct cifs_sb_info *cifs_sb;
1185         struct cifs_tcon *tcon;
1186
1187         if (sd->sb)
1188                 return;
1189
1190         cifs_sb = CIFS_SB(sb);
1191         tcon = cifs_sb_master_tcon(cifs_sb);
1192         if (tcon->ses->server == server)
1193                 sd->sb = sb;
1194 }
1195
1196 static struct super_block *__cifs_get_super(void (*f)(struct super_block *, void *),
1197                                             void *data)
1198 {
1199         struct super_cb_data sd = {
1200                 .data = data,
1201                 .sb = NULL,
1202         };
1203
1204         iterate_supers_type(&cifs_fs_type, f, &sd);
1205
1206         if (!sd.sb)
1207                 return ERR_PTR(-EINVAL);
1208         /*
1209          * Grab an active reference in order to prevent automounts (DFS links)
1210          * of expiring and then freeing up our cifs superblock pointer while
1211          * we're doing failover.
1212          */
1213         cifs_sb_active(sd.sb);
1214         return sd.sb;
1215 }
1216
1217 static void __cifs_put_super(struct super_block *sb)
1218 {
1219         if (!IS_ERR_OR_NULL(sb))
1220                 cifs_sb_deactive(sb);
1221 }
1222
1223 struct super_block *cifs_get_tcp_super(struct TCP_Server_Info *server)
1224 {
1225         return __cifs_get_super(tcp_super_cb, server);
1226 }
1227
1228 void cifs_put_tcp_super(struct super_block *sb)
1229 {
1230         __cifs_put_super(sb);
1231 }
1232
1233 #ifdef CONFIG_CIFS_DFS_UPCALL
1234 int match_target_ip(struct TCP_Server_Info *server,
1235                     const char *share, size_t share_len,
1236                     bool *result)
1237 {
1238         int rc;
1239         char *target, *tip = NULL;
1240         struct sockaddr tipaddr;
1241
1242         *result = false;
1243
1244         target = kzalloc(share_len + 3, GFP_KERNEL);
1245         if (!target) {
1246                 rc = -ENOMEM;
1247                 goto out;
1248         }
1249
1250         scnprintf(target, share_len + 3, "\\\\%.*s", (int)share_len, share);
1251
1252         cifs_dbg(FYI, "%s: target name: %s\n", __func__, target + 2);
1253
1254         rc = dns_resolve_server_name_to_ip(target, &tip, NULL);
1255         if (rc < 0)
1256                 goto out;
1257
1258         cifs_dbg(FYI, "%s: target ip: %s\n", __func__, tip);
1259
1260         if (!cifs_convert_address(&tipaddr, tip, strlen(tip))) {
1261                 cifs_dbg(VFS, "%s: failed to convert target ip address\n",
1262                          __func__);
1263                 rc = -EINVAL;
1264                 goto out;
1265         }
1266
1267         *result = cifs_match_ipaddr((struct sockaddr *)&server->dstaddr,
1268                                     &tipaddr);
1269         cifs_dbg(FYI, "%s: ip addresses match: %u\n", __func__, *result);
1270         rc = 0;
1271
1272 out:
1273         kfree(target);
1274         kfree(tip);
1275
1276         return rc;
1277 }
1278
1279 static void tcon_super_cb(struct super_block *sb, void *arg)
1280 {
1281         struct super_cb_data *sd = arg;
1282         struct cifs_tcon *tcon = sd->data;
1283         struct cifs_sb_info *cifs_sb;
1284
1285         if (sd->sb)
1286                 return;
1287
1288         cifs_sb = CIFS_SB(sb);
1289         if (tcon->dfs_path && cifs_sb->origin_fullpath &&
1290             !strcasecmp(tcon->dfs_path, cifs_sb->origin_fullpath))
1291                 sd->sb = sb;
1292 }
1293
1294 static inline struct super_block *cifs_get_tcon_super(struct cifs_tcon *tcon)
1295 {
1296         return __cifs_get_super(tcon_super_cb, tcon);
1297 }
1298
1299 static inline void cifs_put_tcon_super(struct super_block *sb)
1300 {
1301         __cifs_put_super(sb);
1302 }
1303 #else
1304 static inline struct super_block *cifs_get_tcon_super(struct cifs_tcon *tcon)
1305 {
1306         return ERR_PTR(-EOPNOTSUPP);
1307 }
1308
1309 static inline void cifs_put_tcon_super(struct super_block *sb)
1310 {
1311 }
1312 #endif
1313
1314 int update_super_prepath(struct cifs_tcon *tcon, char *prefix)
1315 {
1316         struct super_block *sb;
1317         struct cifs_sb_info *cifs_sb;
1318         int rc = 0;
1319
1320         sb = cifs_get_tcon_super(tcon);
1321         if (IS_ERR(sb))
1322                 return PTR_ERR(sb);
1323
1324         cifs_sb = CIFS_SB(sb);
1325
1326         kfree(cifs_sb->prepath);
1327
1328         if (prefix && *prefix) {
1329                 cifs_sb->prepath = kstrdup(prefix, GFP_ATOMIC);
1330                 if (!cifs_sb->prepath) {
1331                         rc = -ENOMEM;
1332                         goto out;
1333                 }
1334
1335                 convert_delimiter(cifs_sb->prepath, CIFS_DIR_SEP(cifs_sb));
1336         } else
1337                 cifs_sb->prepath = NULL;
1338
1339         cifs_sb->mnt_cifs_flags |= CIFS_MOUNT_USE_PREFIX_PATH;
1340
1341 out:
1342         cifs_put_tcon_super(sb);
1343         return rc;
1344 }