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 #include "dfs_cache.h"
  25 #include "dfs.h"
  26 #endif
  27 #include "fs_context.h"
  28 #include "cached_dir.h"
  29
  30 extern mempool_t *cifs_sm_req_poolp;
  31 extern mempool_t *cifs_req_poolp;
  32
  33 /* The xid serves as a useful identifier for each incoming vfs request,
  34    in a similar way to the mid which is useful to track each sent smb,
  35    and CurrentXid can also provide a running counter (although it
  36    will eventually wrap past zero) of the total vfs operations handled
  37    since the cifs fs was mounted */
  38
  39 unsigned int
  40 _get_xid(void)
  41 {
  42         unsigned int xid;
  43
  44         spin_lock(&GlobalMid_Lock);
  45         GlobalTotalActiveXid++;
  46
  47         /* keep high water mark for number of simultaneous ops in filesystem */
  48         if (GlobalTotalActiveXid > GlobalMaxActiveXid)
  49                 GlobalMaxActiveXid = GlobalTotalActiveXid;
  50         if (GlobalTotalActiveXid > 65000)
  51                 cifs_dbg(FYI, "warning: more than 65000 requests active\n");
  52         xid = GlobalCurrentXid++;
  53         spin_unlock(&GlobalMid_Lock);
  54         return xid;
  55 }
  56
  57 void
  58 _free_xid(unsigned int xid)
  59 {
  60         spin_lock(&GlobalMid_Lock);
  61         /* if (GlobalTotalActiveXid == 0)
  62                 BUG(); */
  63         GlobalTotalActiveXid--;
  64         spin_unlock(&GlobalMid_Lock);
  65 }
  66
  67 struct cifs_ses *
  68 sesInfoAlloc(void)
  69 {
  70         struct cifs_ses *ret_buf;
  71
  72         ret_buf = kzalloc(sizeof(struct cifs_ses), GFP_KERNEL);
  73         if (ret_buf) {
  74                 atomic_inc(&sesInfoAllocCount);
  75                 spin_lock_init(&ret_buf->ses_lock);
  76                 ret_buf->ses_status = SES_NEW;
  77                 ++ret_buf->ses_count;
  78                 INIT_LIST_HEAD(&ret_buf->smb_ses_list);
  79                 INIT_LIST_HEAD(&ret_buf->tcon_list);
  80                 mutex_init(&ret_buf->session_mutex);
  81                 spin_lock_init(&ret_buf->iface_lock);
  82                 INIT_LIST_HEAD(&ret_buf->iface_list);
  83                 spin_lock_init(&ret_buf->chan_lock);
  84         }
  85         return ret_buf;
  86 }
  87
  88 void
  89 sesInfoFree(struct cifs_ses *buf_to_free)
  90 {
  91         struct cifs_server_iface *iface = NULL, *niface = NULL;
  92
  93         if (buf_to_free == NULL) {
  94                 cifs_dbg(FYI, "Null buffer passed to sesInfoFree\n");
  95                 return;
  96         }
  97
  98         atomic_dec(&sesInfoAllocCount);
  99         kfree(buf_to_free->serverOS);
 100         kfree(buf_to_free->serverDomain);
 101         kfree(buf_to_free->serverNOS);
 102         kfree_sensitive(buf_to_free->password);
 103         kfree(buf_to_free->user_name);
 104         kfree(buf_to_free->domainName);
 105         kfree_sensitive(buf_to_free->auth_key.response);
 106         spin_lock(&buf_to_free->iface_lock);
 107         list_for_each_entry_safe(iface, niface, &buf_to_free->iface_list,
 108                                  iface_head)
 109                 kref_put(&iface->refcount, release_iface);
 110         spin_unlock(&buf_to_free->iface_lock);
 111         kfree_sensitive(buf_to_free);
 112 }
 113
 114 struct cifs_tcon *
 115 tconInfoAlloc(void)
 116 {
 117         struct cifs_tcon *ret_buf;
 118
 119         ret_buf = kzalloc(sizeof(*ret_buf), GFP_KERNEL);
 120         if (!ret_buf)
 121                 return NULL;
 122         ret_buf->cfids = init_cached_dirs();
 123         if (!ret_buf->cfids) {
 124                 kfree(ret_buf);
 125                 return NULL;
 126         }
 127
 128         atomic_inc(&tconInfoAllocCount);
 129         ret_buf->status = TID_NEW;
 130         ++ret_buf->tc_count;
 131         spin_lock_init(&ret_buf->tc_lock);
 132         INIT_LIST_HEAD(&ret_buf->openFileList);
 133         INIT_LIST_HEAD(&ret_buf->tcon_list);
 134         spin_lock_init(&ret_buf->open_file_lock);
 135         spin_lock_init(&ret_buf->stat_lock);
 136         atomic_set(&ret_buf->num_local_opens, 0);
 137         atomic_set(&ret_buf->num_remote_opens, 0);
 138 #ifdef CONFIG_CIFS_DFS_UPCALL
 139         INIT_LIST_HEAD(&ret_buf->dfs_ses_list);
 140 #endif
 141
 142         return ret_buf;
 143 }
 144
 145 void
 146 tconInfoFree(struct cifs_tcon *tcon)
 147 {
 148         if (tcon == NULL) {
 149                 cifs_dbg(FYI, "Null buffer passed to tconInfoFree\n");
 150                 return;
 151         }
 152         free_cached_dirs(tcon->cfids);
 153         atomic_dec(&tconInfoAllocCount);
 154         kfree(tcon->nativeFileSystem);
 155         kfree_sensitive(tcon->password);
 156 #ifdef CONFIG_CIFS_DFS_UPCALL
 157         dfs_put_root_smb_sessions(&tcon->dfs_ses_list);
 158 #endif
 159         kfree(tcon);
 160 }
 161
 162 struct smb_hdr *
 163 cifs_buf_get(void)
 164 {
 165         struct smb_hdr *ret_buf = NULL;
 166         /*
 167          * SMB2 header is bigger than CIFS one - no problems to clean some
 168          * more bytes for CIFS.
 169          */
 170         size_t buf_size = sizeof(struct smb2_hdr);
 171
 172         /*
 173          * We could use negotiated size instead of max_msgsize -
 174          * but it may be more efficient to always alloc same size
 175          * albeit slightly larger than necessary and maxbuffersize
 176          * defaults to this and can not be bigger.
 177          */
 178         ret_buf = mempool_alloc(cifs_req_poolp, GFP_NOFS);
 179
 180         /* clear the first few header bytes */
 181         /* for most paths, more is cleared in header_assemble */
 182         memset(ret_buf, 0, buf_size + 3);
 183         atomic_inc(&buf_alloc_count);
 184 #ifdef CONFIG_CIFS_STATS2
 185         atomic_inc(&total_buf_alloc_count);
 186 #endif /* CONFIG_CIFS_STATS2 */
 187
 188         return ret_buf;
 189 }
 190
 191 void
 192 cifs_buf_release(void *buf_to_free)
 193 {
 194         if (buf_to_free == NULL) {
 195                 /* cifs_dbg(FYI, "Null buffer passed to cifs_buf_release\n");*/
 196                 return;
 197         }
 198         mempool_free(buf_to_free, cifs_req_poolp);
 199
 200         atomic_dec(&buf_alloc_count);
 201         return;
 202 }
 203
 204 struct smb_hdr *
 205 cifs_small_buf_get(void)
 206 {
 207         struct smb_hdr *ret_buf = NULL;
 208
 209 /* We could use negotiated size instead of max_msgsize -
 210    but it may be more efficient to always alloc same size
 211    albeit slightly larger than necessary and maxbuffersize
 212    defaults to this and can not be bigger */
 213         ret_buf = mempool_alloc(cifs_sm_req_poolp, GFP_NOFS);
 214         /* No need to clear memory here, cleared in header assemble */
 215         /*      memset(ret_buf, 0, sizeof(struct smb_hdr) + 27);*/
 216         atomic_inc(&small_buf_alloc_count);
 217 #ifdef CONFIG_CIFS_STATS2
 218         atomic_inc(&total_small_buf_alloc_count);
 219 #endif /* CONFIG_CIFS_STATS2 */
 220
 221         return ret_buf;
 222 }
 223
 224 void
 225 cifs_small_buf_release(void *buf_to_free)
 226 {
 227
 228         if (buf_to_free == NULL) {
 229                 cifs_dbg(FYI, "Null buffer passed to cifs_small_buf_release\n");
 230                 return;
 231         }
 232         mempool_free(buf_to_free, cifs_sm_req_poolp);
 233
 234         atomic_dec(&small_buf_alloc_count);
 235         return;
 236 }
 237
 238 void
 239 free_rsp_buf(int resp_buftype, void *rsp)
 240 {
 241         if (resp_buftype == CIFS_SMALL_BUFFER)
 242                 cifs_small_buf_release(rsp);
 243         else if (resp_buftype == CIFS_LARGE_BUFFER)
 244                 cifs_buf_release(rsp);
 245 }
 246
 247 /* NB: MID can not be set if treeCon not passed in, in that
 248    case it is responsbility of caller to set the mid */
 249 void
 250 header_assemble(struct smb_hdr *buffer, char smb_command /* command */ ,
 251                 const struct cifs_tcon *treeCon, int word_count
 252                 /* length of fixed section (word count) in two byte units  */)
 253 {
 254         char *temp = (char *) buffer;
 255
 256         memset(temp, 0, 256); /* bigger than MAX_CIFS_HDR_SIZE */
 257
 258         buffer->smb_buf_length = cpu_to_be32(
 259             (2 * word_count) + sizeof(struct smb_hdr) -
 260             4 /*  RFC 1001 length field does not count */  +
 261             2 /* for bcc field itself */) ;
 262
 263         buffer->Protocol[0] = 0xFF;
 264         buffer->Protocol[1] = 'S';
 265         buffer->Protocol[2] = 'M';
 266         buffer->Protocol[3] = 'B';
 267         buffer->Command = smb_command;
 268         buffer->Flags = 0x00;   /* case sensitive */
 269         buffer->Flags2 = SMBFLG2_KNOWS_LONG_NAMES;
 270         buffer->Pid = cpu_to_le16((__u16)current->tgid);
 271         buffer->PidHigh = cpu_to_le16((__u16)(current->tgid >> 16));
 272         if (treeCon) {
 273                 buffer->Tid = treeCon->tid;
 274                 if (treeCon->ses) {
 275                         if (treeCon->ses->capabilities & CAP_UNICODE)
 276                                 buffer->Flags2 |= SMBFLG2_UNICODE;
 277                         if (treeCon->ses->capabilities & CAP_STATUS32)
 278                                 buffer->Flags2 |= SMBFLG2_ERR_STATUS;
 279
 280                         /* Uid is not converted */
 281                         buffer->Uid = treeCon->ses->Suid;
 282                         if (treeCon->ses->server)
 283                                 buffer->Mid = get_next_mid(treeCon->ses->server);
 284                 }
 285                 if (treeCon->Flags & SMB_SHARE_IS_IN_DFS)
 286                         buffer->Flags2 |= SMBFLG2_DFS;
 287                 if (treeCon->nocase)
 288                         buffer->Flags  |= SMBFLG_CASELESS;
 289                 if ((treeCon->ses) && (treeCon->ses->server))
 290                         if (treeCon->ses->server->sign)
 291                                 buffer->Flags2 |= SMBFLG2_SECURITY_SIGNATURE;
 292         }
 293
 294 /*  endian conversion of flags is now done just before sending */
 295         buffer->WordCount = (char) word_count;
 296         return;
 297 }
 298
 299 static int
 300 check_smb_hdr(struct smb_hdr *smb)
 301 {
 302         /* does it have the right SMB "signature" ? */
 303         if (*(__le32 *) smb->Protocol != cpu_to_le32(0x424d53ff)) {
 304                 cifs_dbg(VFS, "Bad protocol string signature header 0x%x\n",
 305                          *(unsigned int *)smb->Protocol);
 306                 return 1;
 307         }
 308
 309         /* if it's a response then accept */
 310         if (smb->Flags & SMBFLG_RESPONSE)
 311                 return 0;
 312
 313         /* only one valid case where server sends us request */
 314         if (smb->Command == SMB_COM_LOCKING_ANDX)
 315                 return 0;
 316
 317         cifs_dbg(VFS, "Server sent request, not response. mid=%u\n",
 318                  get_mid(smb));
 319         return 1;
 320 }
 321
 322 int
 323 checkSMB(char *buf, unsigned int total_read, struct TCP_Server_Info *server)
 324 {
 325         struct smb_hdr *smb = (struct smb_hdr *)buf;
 326         __u32 rfclen = be32_to_cpu(smb->smb_buf_length);
 327         __u32 clc_len;  /* calculated length */
 328         cifs_dbg(FYI, "checkSMB Length: 0x%x, smb_buf_length: 0x%x\n",
 329                  total_read, rfclen);
 330
 331         /* is this frame too small to even get to a BCC? */
 332         if (total_read < 2 + sizeof(struct smb_hdr)) {
 333                 if ((total_read >= sizeof(struct smb_hdr) - 1)
 334                             && (smb->Status.CifsError != 0)) {
 335                         /* it's an error return */
 336                         smb->WordCount = 0;
 337                         /* some error cases do not return wct and bcc */
 338                         return 0;
 339                 } else if ((total_read == sizeof(struct smb_hdr) + 1) &&
 340                                 (smb->WordCount == 0)) {
 341                         char *tmp = (char *)smb;
 342                         /* Need to work around a bug in two servers here */
 343                         /* First, check if the part of bcc they sent was zero */
 344                         if (tmp[sizeof(struct smb_hdr)] == 0) {
 345                                 /* some servers return only half of bcc
 346                                  * on simple responses (wct, bcc both zero)
 347                                  * in particular have seen this on
 348                                  * ulogoffX and FindClose. This leaves
 349                                  * one byte of bcc potentially unitialized
 350                                  */
 351                                 /* zero rest of bcc */
 352                                 tmp[sizeof(struct smb_hdr)+1] = 0;
 353                                 return 0;
 354                         }
 355                         cifs_dbg(VFS, "rcvd invalid byte count (bcc)\n");
 356                 } else {
 357                         cifs_dbg(VFS, "Length less than smb header size\n");
 358                 }
 359                 return -EIO;
 360         }
 361
 362         /* otherwise, there is enough to get to the BCC */
 363         if (check_smb_hdr(smb))
 364                 return -EIO;
 365         clc_len = smbCalcSize(smb);
 366
 367         if (4 + rfclen != total_read) {
 368                 cifs_dbg(VFS, "Length read does not match RFC1001 length %d\n",
 369                          rfclen);
 370                 return -EIO;
 371         }
 372
 373         if (4 + rfclen != clc_len) {
 374                 __u16 mid = get_mid(smb);
 375                 /* check if bcc wrapped around for large read responses */
 376                 if ((rfclen > 64 * 1024) && (rfclen > clc_len)) {
 377                         /* check if lengths match mod 64K */
 378                         if (((4 + rfclen) & 0xFFFF) == (clc_len & 0xFFFF))
 379                                 return 0; /* bcc wrapped */
 380                 }
 381                 cifs_dbg(FYI, "Calculated size %u vs length %u mismatch for mid=%u\n",
 382                          clc_len, 4 + rfclen, mid);
 383
 384                 if (4 + rfclen < clc_len) {
 385                         cifs_dbg(VFS, "RFC1001 size %u smaller than SMB for mid=%u\n",
 386                                  rfclen, mid);
 387                         return -EIO;
 388                 } else if (rfclen > clc_len + 512) {
 389                         /*
 390                          * Some servers (Windows XP in particular) send more
 391                          * data than the lengths in the SMB packet would
 392                          * indicate on certain calls (byte range locks and
 393                          * trans2 find first calls in particular). While the
 394                          * client can handle such a frame by ignoring the
 395                          * trailing data, we choose limit the amount of extra
 396                          * data to 512 bytes.
 397                          */
 398                         cifs_dbg(VFS, "RFC1001 size %u more than 512 bytes larger than SMB for mid=%u\n",
 399                                  rfclen, mid);
 400                         return -EIO;
 401                 }
 402         }
 403         return 0;
 404 }
 405
 406 bool
 407 is_valid_oplock_break(char *buffer, struct TCP_Server_Info *srv)
 408 {
 409         struct smb_hdr *buf = (struct smb_hdr *)buffer;
 410         struct smb_com_lock_req *pSMB = (struct smb_com_lock_req *)buf;
 411         struct TCP_Server_Info *pserver;
 412         struct cifs_ses *ses;
 413         struct cifs_tcon *tcon;
 414         struct cifsInodeInfo *pCifsInode;
 415         struct cifsFileInfo *netfile;
 416
 417         cifs_dbg(FYI, "Checking for oplock break or dnotify response\n");
 418         if ((pSMB->hdr.Command == SMB_COM_NT_TRANSACT) &&
 419            (pSMB->hdr.Flags & SMBFLG_RESPONSE)) {
 420                 struct smb_com_transaction_change_notify_rsp *pSMBr =
 421                         (struct smb_com_transaction_change_notify_rsp *)buf;
 422                 struct file_notify_information *pnotify;
 423                 __u32 data_offset = 0;
 424                 size_t len = srv->total_read - sizeof(pSMBr->hdr.smb_buf_length);
 425
 426                 if (get_bcc(buf) > sizeof(struct file_notify_information)) {
 427                         data_offset = le32_to_cpu(pSMBr->DataOffset);
 428
 429                         if (data_offset >
 430                             len - sizeof(struct file_notify_information)) {
 431                                 cifs_dbg(FYI, "Invalid data_offset %u\n",
 432                                          data_offset);
 433                                 return true;
 434                         }
 435                         pnotify = (struct file_notify_information *)
 436                                 ((char *)&pSMBr->hdr.Protocol + data_offset);
 437                         cifs_dbg(FYI, "dnotify on %s Action: 0x%x\n",
 438                                  pnotify->FileName, pnotify->Action);
 439                         /*   cifs_dump_mem("Rcvd notify Data: ",buf,
 440                                 sizeof(struct smb_hdr)+60); */
 441                         return true;
 442                 }
 443                 if (pSMBr->hdr.Status.CifsError) {
 444                         cifs_dbg(FYI, "notify err 0x%x\n",
 445                                  pSMBr->hdr.Status.CifsError);
 446                         return true;
 447                 }
 448                 return false;
 449         }
 450         if (pSMB->hdr.Command != SMB_COM_LOCKING_ANDX)
 451                 return false;
 452         if (pSMB->hdr.Flags & SMBFLG_RESPONSE) {
 453                 /* no sense logging error on invalid handle on oplock
 454                    break - harmless race between close request and oplock
 455                    break response is expected from time to time writing out
 456                    large dirty files cached on the client */
 457                 if ((NT_STATUS_INVALID_HANDLE) ==
 458                    le32_to_cpu(pSMB->hdr.Status.CifsError)) {
 459                         cifs_dbg(FYI, "Invalid handle on oplock break\n");
 460                         return true;
 461                 } else if (ERRbadfid ==
 462                    le16_to_cpu(pSMB->hdr.Status.DosError.Error)) {
 463                         return true;
 464                 } else {
 465                         return false; /* on valid oplock brk we get "request" */
 466                 }
 467         }
 468         if (pSMB->hdr.WordCount != 8)
 469                 return false;
 470
 471         cifs_dbg(FYI, "oplock type 0x%x level 0x%x\n",
 472                  pSMB->LockType, pSMB->OplockLevel);
 473         if (!(pSMB->LockType & LOCKING_ANDX_OPLOCK_RELEASE))
 474                 return false;
 475
 476         /* If server is a channel, select the primary channel */
 477         pserver = CIFS_SERVER_IS_CHAN(srv) ? srv->primary_server : srv;
 478
 479         /* look up tcon based on tid & uid */
 480         spin_lock(&cifs_tcp_ses_lock);
 481         list_for_each_entry(ses, &pserver->smb_ses_list, smb_ses_list) {
 482                 list_for_each_entry(tcon, &ses->tcon_list, tcon_list) {
 483                         if (tcon->tid != buf->Tid)
 484                                 continue;
 485
 486                         cifs_stats_inc(&tcon->stats.cifs_stats.num_oplock_brks);
 487                         spin_lock(&tcon->open_file_lock);
 488                         list_for_each_entry(netfile, &tcon->openFileList, tlist) {
 489                                 if (pSMB->Fid != netfile->fid.netfid)
 490                                         continue;
 491
 492                                 cifs_dbg(FYI, "file id match, oplock break\n");
 493                                 pCifsInode = CIFS_I(d_inode(netfile->dentry));
 494
 495                                 set_bit(CIFS_INODE_PENDING_OPLOCK_BREAK,
 496                                         &pCifsInode->flags);
 497
 498                                 netfile->oplock_epoch = 0;
 499                                 netfile->oplock_level = pSMB->OplockLevel;
 500                                 netfile->oplock_break_cancelled = false;
 501                                 cifs_queue_oplock_break(netfile);
 502
 503                                 spin_unlock(&tcon->open_file_lock);
 504                                 spin_unlock(&cifs_tcp_ses_lock);
 505                                 return true;
 506                         }
 507                         spin_unlock(&tcon->open_file_lock);
 508                         spin_unlock(&cifs_tcp_ses_lock);
 509                         cifs_dbg(FYI, "No matching file for oplock break\n");
 510                         return true;
 511                 }
 512         }
 513         spin_unlock(&cifs_tcp_ses_lock);
 514         cifs_dbg(FYI, "Can not process oplock break for non-existent connection\n");
 515         return true;
 516 }
 517
 518 void
 519 dump_smb(void *buf, int smb_buf_length)
 520 {
 521         if (traceSMB == 0)
 522                 return;
 523
 524         print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_NONE, 8, 2, buf,
 525                        smb_buf_length, true);
 526 }
 527
 528 void
 529 cifs_autodisable_serverino(struct cifs_sb_info *cifs_sb)
 530 {
 531         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SERVER_INUM) {
 532                 struct cifs_tcon *tcon = NULL;
 533
 534                 if (cifs_sb->master_tlink)
 535                         tcon = cifs_sb_master_tcon(cifs_sb);
 536
 537                 cifs_sb->mnt_cifs_flags &= ~CIFS_MOUNT_SERVER_INUM;
 538                 cifs_sb->mnt_cifs_serverino_autodisabled = true;
 539                 cifs_dbg(VFS, "Autodisabling the use of server inode numbers on %s\n",
 540                          tcon ? tcon->tree_name : "new server");
 541                 cifs_dbg(VFS, "The server doesn't seem to support them properly or the files might be on different servers (DFS)\n");
 542                 cifs_dbg(VFS, "Hardlinks will not be recognized on this mount. Consider mounting with the \"noserverino\" option to silence this message.\n");
 543
 544         }
 545 }
 546
 547 void cifs_set_oplock_level(struct cifsInodeInfo *cinode, __u32 oplock)
 548 {
 549         oplock &= 0xF;
 550
 551         if (oplock == OPLOCK_EXCLUSIVE) {
 552                 cinode->oplock = CIFS_CACHE_WRITE_FLG | CIFS_CACHE_READ_FLG;
 553                 cifs_dbg(FYI, "Exclusive Oplock granted on inode %p\n",
 554                          &cinode->netfs.inode);
 555         } else if (oplock == OPLOCK_READ) {
 556                 cinode->oplock = CIFS_CACHE_READ_FLG;
 557                 cifs_dbg(FYI, "Level II Oplock granted on inode %p\n",
 558                          &cinode->netfs.inode);
 559         } else
 560                 cinode->oplock = 0;
 561 }
 562
 563 /*
 564  * We wait for oplock breaks to be processed before we attempt to perform
 565  * writes.
 566  */
 567 int cifs_get_writer(struct cifsInodeInfo *cinode)
 568 {
 569         int rc;
 570
 571 start:
 572         rc = wait_on_bit(&cinode->flags, CIFS_INODE_PENDING_OPLOCK_BREAK,
 573                          TASK_KILLABLE);
 574         if (rc)
 575                 return rc;
 576
 577         spin_lock(&cinode->writers_lock);
 578         if (!cinode->writers)
 579                 set_bit(CIFS_INODE_PENDING_WRITERS, &cinode->flags);
 580         cinode->writers++;
 581         /* Check to see if we have started servicing an oplock break */
 582         if (test_bit(CIFS_INODE_PENDING_OPLOCK_BREAK, &cinode->flags)) {
 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                 goto start;
 590         }
 591         spin_unlock(&cinode->writers_lock);
 592         return 0;
 593 }
 594
 595 void cifs_put_writer(struct cifsInodeInfo *cinode)
 596 {
 597         spin_lock(&cinode->writers_lock);
 598         cinode->writers--;
 599         if (cinode->writers == 0) {
 600                 clear_bit(CIFS_INODE_PENDING_WRITERS, &cinode->flags);
 601                 wake_up_bit(&cinode->flags, CIFS_INODE_PENDING_WRITERS);
 602         }
 603         spin_unlock(&cinode->writers_lock);
 604 }
 605
 606 /**
 607  * cifs_queue_oplock_break - queue the oplock break handler for cfile
 608  * @cfile: The file to break the oplock on
 609  *
 610  * This function is called from the demultiplex thread when it
 611  * receives an oplock break for @cfile.
 612  *
 613  * Assumes the tcon->open_file_lock is held.
 614  * Assumes cfile->file_info_lock is NOT held.
 615  */
 616 void cifs_queue_oplock_break(struct cifsFileInfo *cfile)
 617 {
 618         /*
 619          * Bump the handle refcount now while we hold the
 620          * open_file_lock to enforce the validity of it for the oplock
 621          * break handler. The matching put is done at the end of the
 622          * handler.
 623          */
 624         cifsFileInfo_get(cfile);
 625
 626         queue_work(cifsoplockd_wq, &cfile->oplock_break);
 627 }
 628
 629 void cifs_done_oplock_break(struct cifsInodeInfo *cinode)
 630 {
 631         clear_bit(CIFS_INODE_PENDING_OPLOCK_BREAK, &cinode->flags);
 632         wake_up_bit(&cinode->flags, CIFS_INODE_PENDING_OPLOCK_BREAK);
 633 }
 634
 635 bool
 636 backup_cred(struct cifs_sb_info *cifs_sb)
 637 {
 638         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_BACKUPUID) {
 639                 if (uid_eq(cifs_sb->ctx->backupuid, current_fsuid()))
 640                         return true;
 641         }
 642         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_BACKUPGID) {
 643                 if (in_group_p(cifs_sb->ctx->backupgid))
 644                         return true;
 645         }
 646
 647         return false;
 648 }
 649
 650 void
 651 cifs_del_pending_open(struct cifs_pending_open *open)
 652 {
 653         spin_lock(&tlink_tcon(open->tlink)->open_file_lock);
 654         list_del(&open->olist);
 655         spin_unlock(&tlink_tcon(open->tlink)->open_file_lock);
 656 }
 657
 658 void
 659 cifs_add_pending_open_locked(struct cifs_fid *fid, struct tcon_link *tlink,
 660                              struct cifs_pending_open *open)
 661 {
 662         memcpy(open->lease_key, fid->lease_key, SMB2_LEASE_KEY_SIZE);
 663         open->oplock = CIFS_OPLOCK_NO_CHANGE;
 664         open->tlink = tlink;
 665         fid->pending_open = open;
 666         list_add_tail(&open->olist, &tlink_tcon(tlink)->pending_opens);
 667 }
 668
 669 void
 670 cifs_add_pending_open(struct cifs_fid *fid, struct tcon_link *tlink,
 671                       struct cifs_pending_open *open)
 672 {
 673         spin_lock(&tlink_tcon(tlink)->open_file_lock);
 674         cifs_add_pending_open_locked(fid, tlink, open);
 675         spin_unlock(&tlink_tcon(open->tlink)->open_file_lock);
 676 }
 677
 678 /*
 679  * Critical section which runs after acquiring deferred_lock.
 680  * As there is no reference count on cifs_deferred_close, pdclose
 681  * should not be used outside deferred_lock.
 682  */
 683 bool
 684 cifs_is_deferred_close(struct cifsFileInfo *cfile, struct cifs_deferred_close **pdclose)
 685 {
 686         struct cifs_deferred_close *dclose;
 687
 688         list_for_each_entry(dclose, &CIFS_I(d_inode(cfile->dentry))->deferred_closes, dlist) {
 689                 if ((dclose->netfid == cfile->fid.netfid) &&
 690                         (dclose->persistent_fid == cfile->fid.persistent_fid) &&
 691                         (dclose->volatile_fid == cfile->fid.volatile_fid)) {
 692                         *pdclose = dclose;
 693                         return true;
 694                 }
 695         }
 696         return false;
 697 }
 698
 699 /*
 700  * Critical section which runs after acquiring deferred_lock.
 701  */
 702 void
 703 cifs_add_deferred_close(struct cifsFileInfo *cfile, struct cifs_deferred_close *dclose)
 704 {
 705         bool is_deferred = false;
 706         struct cifs_deferred_close *pdclose;
 707
 708         is_deferred = cifs_is_deferred_close(cfile, &pdclose);
 709         if (is_deferred) {
 710                 kfree(dclose);
 711                 return;
 712         }
 713
 714         dclose->tlink = cfile->tlink;
 715         dclose->netfid = cfile->fid.netfid;
 716         dclose->persistent_fid = cfile->fid.persistent_fid;
 717         dclose->volatile_fid = cfile->fid.volatile_fid;
 718         list_add_tail(&dclose->dlist, &CIFS_I(d_inode(cfile->dentry))->deferred_closes);
 719 }
 720
 721 /*
 722  * Critical section which runs after acquiring deferred_lock.
 723  */
 724 void
 725 cifs_del_deferred_close(struct cifsFileInfo *cfile)
 726 {
 727         bool is_deferred = false;
 728         struct cifs_deferred_close *dclose;
 729
 730         is_deferred = cifs_is_deferred_close(cfile, &dclose);
 731         if (!is_deferred)
 732                 return;
 733         list_del(&dclose->dlist);
 734         kfree(dclose);
 735 }
 736
 737 void
 738 cifs_close_deferred_file(struct cifsInodeInfo *cifs_inode)
 739 {
 740         struct cifsFileInfo *cfile = NULL;
 741         struct file_list *tmp_list, *tmp_next_list;
 742         struct list_head file_head;
 743
 744         if (cifs_inode == NULL)
 745                 return;
 746
 747         INIT_LIST_HEAD(&file_head);
 748         spin_lock(&cifs_inode->open_file_lock);
 749         list_for_each_entry(cfile, &cifs_inode->openFileList, flist) {
 750                 if (delayed_work_pending(&cfile->deferred)) {
 751                         if (cancel_delayed_work(&cfile->deferred)) {
 752                                 cifs_del_deferred_close(cfile);
 753
 754                                 tmp_list = kmalloc(sizeof(struct file_list), GFP_ATOMIC);
 755                                 if (tmp_list == NULL)
 756                                         break;
 757                                 tmp_list->cfile = cfile;
 758                                 list_add_tail(&tmp_list->list, &file_head);
 759                         }
 760                 }
 761         }
 762         spin_unlock(&cifs_inode->open_file_lock);
 763
 764         list_for_each_entry_safe(tmp_list, tmp_next_list, &file_head, list) {
 765                 _cifsFileInfo_put(tmp_list->cfile, true, false);
 766                 list_del(&tmp_list->list);
 767                 kfree(tmp_list);
 768         }
 769 }
 770
 771 void
 772 cifs_close_all_deferred_files(struct cifs_tcon *tcon)
 773 {
 774         struct cifsFileInfo *cfile;
 775         struct file_list *tmp_list, *tmp_next_list;
 776         struct list_head file_head;
 777
 778         INIT_LIST_HEAD(&file_head);
 779         spin_lock(&tcon->open_file_lock);
 780         list_for_each_entry(cfile, &tcon->openFileList, tlist) {
 781                 if (delayed_work_pending(&cfile->deferred)) {
 782                         if (cancel_delayed_work(&cfile->deferred)) {
 783                                 cifs_del_deferred_close(cfile);
 784
 785                                 tmp_list = kmalloc(sizeof(struct file_list), GFP_ATOMIC);
 786                                 if (tmp_list == NULL)
 787                                         break;
 788                                 tmp_list->cfile = cfile;
 789                                 list_add_tail(&tmp_list->list, &file_head);
 790                         }
 791                 }
 792         }
 793         spin_unlock(&tcon->open_file_lock);
 794
 795         list_for_each_entry_safe(tmp_list, tmp_next_list, &file_head, list) {
 796                 _cifsFileInfo_put(tmp_list->cfile, true, false);
 797                 list_del(&tmp_list->list);
 798                 kfree(tmp_list);
 799         }
 800 }
 801 void
 802 cifs_close_deferred_file_under_dentry(struct cifs_tcon *tcon, const char *path)
 803 {
 804         struct cifsFileInfo *cfile;
 805         struct file_list *tmp_list, *tmp_next_list;
 806         struct list_head file_head;
 807         void *page;
 808         const char *full_path;
 809
 810         INIT_LIST_HEAD(&file_head);
 811         page = alloc_dentry_path();
 812         spin_lock(&tcon->open_file_lock);
 813         list_for_each_entry(cfile, &tcon->openFileList, tlist) {
 814                 full_path = build_path_from_dentry(cfile->dentry, page);
 815                 if (strstr(full_path, path)) {
 816                         if (delayed_work_pending(&cfile->deferred)) {
 817                                 if (cancel_delayed_work(&cfile->deferred)) {
 818                                         cifs_del_deferred_close(cfile);
 819
 820                                         tmp_list = kmalloc(sizeof(struct file_list), GFP_ATOMIC);
 821                                         if (tmp_list == NULL)
 822                                                 break;
 823                                         tmp_list->cfile = cfile;
 824                                         list_add_tail(&tmp_list->list, &file_head);
 825                                 }
 826                         }
 827                 }
 828         }
 829         spin_unlock(&tcon->open_file_lock);
 830
 831         list_for_each_entry_safe(tmp_list, tmp_next_list, &file_head, list) {
 832                 _cifsFileInfo_put(tmp_list->cfile, true, false);
 833                 list_del(&tmp_list->list);
 834                 kfree(tmp_list);
 835         }
 836         free_dentry_path(page);
 837 }
 838
 839 /* parses DFS referral V3 structure
 840  * caller is responsible for freeing target_nodes
 841  * returns:
 842  * - on success - 0
 843  * - on failure - errno
 844  */
 845 int
 846 parse_dfs_referrals(struct get_dfs_referral_rsp *rsp, u32 rsp_size,
 847                     unsigned int *num_of_nodes,
 848                     struct dfs_info3_param **target_nodes,
 849                     const struct nls_table *nls_codepage, int remap,
 850                     const char *searchName, bool is_unicode)
 851 {
 852         int i, rc = 0;
 853         char *data_end;
 854         struct dfs_referral_level_3 *ref;
 855
 856         *num_of_nodes = le16_to_cpu(rsp->NumberOfReferrals);
 857
 858         if (*num_of_nodes < 1) {
 859                 cifs_dbg(VFS, "num_referrals: must be at least > 0, but we get num_referrals = %d\n",
 860                          *num_of_nodes);
 861                 rc = -EINVAL;
 862                 goto parse_DFS_referrals_exit;
 863         }
 864
 865         ref = (struct dfs_referral_level_3 *) &(rsp->referrals);
 866         if (ref->VersionNumber != cpu_to_le16(3)) {
 867                 cifs_dbg(VFS, "Referrals of V%d version are not supported, should be V3\n",
 868                          le16_to_cpu(ref->VersionNumber));
 869                 rc = -EINVAL;
 870                 goto parse_DFS_referrals_exit;
 871         }
 872
 873         /* get the upper boundary of the resp buffer */
 874         data_end = (char *)rsp + rsp_size;
 875
 876         cifs_dbg(FYI, "num_referrals: %d dfs flags: 0x%x ...\n",
 877                  *num_of_nodes, le32_to_cpu(rsp->DFSFlags));
 878
 879         *target_nodes = kcalloc(*num_of_nodes, sizeof(struct dfs_info3_param),
 880                                 GFP_KERNEL);
 881         if (*target_nodes == NULL) {
 882                 rc = -ENOMEM;
 883                 goto parse_DFS_referrals_exit;
 884         }
 885
 886         /* collect necessary data from referrals */
 887         for (i = 0; i < *num_of_nodes; i++) {
 888                 char *temp;
 889                 int max_len;
 890                 struct dfs_info3_param *node = (*target_nodes)+i;
 891
 892                 node->flags = le32_to_cpu(rsp->DFSFlags);
 893                 if (is_unicode) {
 894                         __le16 *tmp = kmalloc(strlen(searchName)*2 + 2,
 895                                                 GFP_KERNEL);
 896                         if (tmp == NULL) {
 897                                 rc = -ENOMEM;
 898                                 goto parse_DFS_referrals_exit;
 899                         }
 900                         cifsConvertToUTF16((__le16 *) tmp, searchName,
 901                                            PATH_MAX, nls_codepage, remap);
 902                         node->path_consumed = cifs_utf16_bytes(tmp,
 903                                         le16_to_cpu(rsp->PathConsumed),
 904                                         nls_codepage);
 905                         kfree(tmp);
 906                 } else
 907                         node->path_consumed = le16_to_cpu(rsp->PathConsumed);
 908
 909                 node->server_type = le16_to_cpu(ref->ServerType);
 910                 node->ref_flag = le16_to_cpu(ref->ReferralEntryFlags);
 911
 912                 /* copy DfsPath */
 913                 temp = (char *)ref + le16_to_cpu(ref->DfsPathOffset);
 914                 max_len = data_end - temp;
 915                 node->path_name = cifs_strndup_from_utf16(temp, max_len,
 916                                                 is_unicode, nls_codepage);
 917                 if (!node->path_name) {
 918                         rc = -ENOMEM;
 919                         goto parse_DFS_referrals_exit;
 920                 }
 921
 922                 /* copy link target UNC */
 923                 temp = (char *)ref + le16_to_cpu(ref->NetworkAddressOffset);
 924                 max_len = data_end - temp;
 925                 node->node_name = cifs_strndup_from_utf16(temp, max_len,
 926                                                 is_unicode, nls_codepage);
 927                 if (!node->node_name) {
 928                         rc = -ENOMEM;
 929                         goto parse_DFS_referrals_exit;
 930                 }
 931
 932                 node->ttl = le32_to_cpu(ref->TimeToLive);
 933
 934                 ref++;
 935         }
 936
 937 parse_DFS_referrals_exit:
 938         if (rc) {
 939                 free_dfs_info_array(*target_nodes, *num_of_nodes);
 940                 *target_nodes = NULL;
 941                 *num_of_nodes = 0;
 942         }
 943         return rc;
 944 }
 945
 946 struct cifs_aio_ctx *
 947 cifs_aio_ctx_alloc(void)
 948 {
 949         struct cifs_aio_ctx *ctx;
 950
 951         /*
 952          * Must use kzalloc to initialize ctx->bv to NULL and ctx->direct_io
 953          * to false so that we know when we have to unreference pages within
 954          * cifs_aio_ctx_release()
 955          */
 956         ctx = kzalloc(sizeof(struct cifs_aio_ctx), GFP_KERNEL);
 957         if (!ctx)
 958                 return NULL;
 959
 960         INIT_LIST_HEAD(&ctx->list);
 961         mutex_init(&ctx->aio_mutex);
 962         init_completion(&ctx->done);
 963         kref_init(&ctx->refcount);
 964         return ctx;
 965 }
 966
 967 void
 968 cifs_aio_ctx_release(struct kref *refcount)
 969 {
 970         struct cifs_aio_ctx *ctx = container_of(refcount,
 971                                         struct cifs_aio_ctx, refcount);
 972
 973         cifsFileInfo_put(ctx->cfile);
 974
 975         /*
 976          * ctx->bv is only set if setup_aio_ctx_iter() was call successfuly
 977          * which means that iov_iter_extract_pages() was a success and thus
 978          * that we may have references or pins on pages that we need to
 979          * release.
 980          */
 981         if (ctx->bv) {
 982                 if (ctx->should_dirty || ctx->bv_need_unpin) {
 983                         unsigned int i;
 984
 985                         for (i = 0; i < ctx->nr_pinned_pages; i++) {
 986                                 struct page *page = ctx->bv[i].bv_page;
 987
 988                                 if (ctx->should_dirty)
 989                                         set_page_dirty(page);
 990                                 if (ctx->bv_need_unpin)
 991                                         unpin_user_page(page);
 992                         }
 993                 }
 994                 kvfree(ctx->bv);
 995         }
 996
 997         kfree(ctx);
 998 }
 999
1000 /**
1001  * cifs_alloc_hash - allocate hash and hash context together
1002  * @name: The name of the crypto hash algo
1003  * @sdesc: SHASH descriptor where to put the pointer to the hash TFM
1004  *
1005  * The caller has to make sure @sdesc is initialized to either NULL or
1006  * a valid context. It can be freed via cifs_free_hash().
1007  */
1008 int
1009 cifs_alloc_hash(const char *name, struct shash_desc **sdesc)
1010 {
1011         int rc = 0;
1012         struct crypto_shash *alg = NULL;
1013
1014         if (*sdesc)
1015                 return 0;
1016
1017         alg = crypto_alloc_shash(name, 0, 0);
1018         if (IS_ERR(alg)) {
1019                 cifs_dbg(VFS, "Could not allocate shash TFM '%s'\n", name);
1020                 rc = PTR_ERR(alg);
1021                 *sdesc = NULL;
1022                 return rc;
1023         }
1024
1025         *sdesc = kmalloc(sizeof(struct shash_desc) + crypto_shash_descsize(alg), GFP_KERNEL);
1026         if (*sdesc == NULL) {
1027                 cifs_dbg(VFS, "no memory left to allocate shash TFM '%s'\n", name);
1028                 crypto_free_shash(alg);
1029                 return -ENOMEM;
1030         }
1031
1032         (*sdesc)->tfm = alg;
1033         return 0;
1034 }
1035
1036 /**
1037  * cifs_free_hash - free hash and hash context together
1038  * @sdesc: Where to find the pointer to the hash TFM
1039  *
1040  * Freeing a NULL descriptor is safe.
1041  */
1042 void
1043 cifs_free_hash(struct shash_desc **sdesc)
1044 {
1045         if (unlikely(!sdesc) || !*sdesc)
1046                 return;
1047
1048         if ((*sdesc)->tfm) {
1049                 crypto_free_shash((*sdesc)->tfm);
1050                 (*sdesc)->tfm = NULL;
1051         }
1052
1053         kfree_sensitive(*sdesc);
1054         *sdesc = NULL;
1055 }
1056
1057 void extract_unc_hostname(const char *unc, const char **h, size_t *len)
1058 {
1059         const char *end;
1060
1061         /* skip initial slashes */
1062         while (*unc && (*unc == '\\' || *unc == '/'))
1063                 unc++;
1064
1065         end = unc;
1066
1067         while (*end && !(*end == '\\' || *end == '/'))
1068                 end++;
1069
1070         *h = unc;
1071         *len = end - unc;
1072 }
1073
1074 /**
1075  * copy_path_name - copy src path to dst, possibly truncating
1076  * @dst: The destination buffer
1077  * @src: The source name
1078  *
1079  * returns number of bytes written (including trailing nul)
1080  */
1081 int copy_path_name(char *dst, const char *src)
1082 {
1083         int name_len;
1084
1085         /*
1086          * PATH_MAX includes nul, so if strlen(src) >= PATH_MAX it
1087          * will truncate and strlen(dst) will be PATH_MAX-1
1088          */
1089         name_len = strscpy(dst, src, PATH_MAX);
1090         if (WARN_ON_ONCE(name_len < 0))
1091                 name_len = PATH_MAX-1;
1092
1093         /* we count the trailing nul */
1094         name_len++;
1095         return name_len;
1096 }
1097
1098 struct super_cb_data {
1099         void *data;
1100         struct super_block *sb;
1101 };
1102
1103 static void tcp_super_cb(struct super_block *sb, void *arg)
1104 {
1105         struct super_cb_data *sd = arg;
1106         struct TCP_Server_Info *server = sd->data;
1107         struct cifs_sb_info *cifs_sb;
1108         struct cifs_tcon *tcon;
1109
1110         if (sd->sb)
1111                 return;
1112
1113         cifs_sb = CIFS_SB(sb);
1114         tcon = cifs_sb_master_tcon(cifs_sb);
1115         if (tcon->ses->server == server)
1116                 sd->sb = sb;
1117 }
1118
1119 static struct super_block *__cifs_get_super(void (*f)(struct super_block *, void *),
1120                                             void *data)
1121 {
1122         struct super_cb_data sd = {
1123                 .data = data,
1124                 .sb = NULL,
1125         };
1126         struct file_system_type **fs_type = (struct file_system_type *[]) {
1127                 &cifs_fs_type, &smb3_fs_type, NULL,
1128         };
1129
1130         for (; *fs_type; fs_type++) {
1131                 iterate_supers_type(*fs_type, f, &sd);
1132                 if (sd.sb) {
1133                         /*
1134                          * Grab an active reference in order to prevent automounts (DFS links)
1135                          * of expiring and then freeing up our cifs superblock pointer while
1136                          * we're doing failover.
1137                          */
1138                         cifs_sb_active(sd.sb);
1139                         return sd.sb;
1140                 }
1141         }
1142         return ERR_PTR(-EINVAL);
1143 }
1144
1145 static void __cifs_put_super(struct super_block *sb)
1146 {
1147         if (!IS_ERR_OR_NULL(sb))
1148                 cifs_sb_deactive(sb);
1149 }
1150
1151 struct super_block *cifs_get_tcp_super(struct TCP_Server_Info *server)
1152 {
1153         return __cifs_get_super(tcp_super_cb, server);
1154 }
1155
1156 void cifs_put_tcp_super(struct super_block *sb)
1157 {
1158         __cifs_put_super(sb);
1159 }
1160
1161 #ifdef CONFIG_CIFS_DFS_UPCALL
1162 int match_target_ip(struct TCP_Server_Info *server,
1163                     const char *share, size_t share_len,
1164                     bool *result)
1165 {
1166         int rc;
1167         char *target;
1168         struct sockaddr_storage ss;
1169
1170         *result = false;
1171
1172         target = kzalloc(share_len + 3, GFP_KERNEL);
1173         if (!target)
1174                 return -ENOMEM;
1175
1176         scnprintf(target, share_len + 3, "\\\\%.*s", (int)share_len, share);
1177
1178         cifs_dbg(FYI, "%s: target name: %s\n", __func__, target + 2);
1179
1180         rc = dns_resolve_server_name_to_ip(target, (struct sockaddr *)&ss, NULL);
1181         kfree(target);
1182
1183         if (rc < 0)
1184                 return rc;
1185
1186         spin_lock(&server->srv_lock);
1187         *result = cifs_match_ipaddr((struct sockaddr *)&server->dstaddr, (struct sockaddr *)&ss);
1188         spin_unlock(&server->srv_lock);
1189         cifs_dbg(FYI, "%s: ip addresses match: %u\n", __func__, *result);
1190         return 0;
1191 }
1192
1193 int cifs_update_super_prepath(struct cifs_sb_info *cifs_sb, char *prefix)
1194 {
1195         kfree(cifs_sb->prepath);
1196
1197         if (prefix && *prefix) {
1198                 cifs_sb->prepath = kstrdup(prefix, GFP_ATOMIC);
1199                 if (!cifs_sb->prepath)
1200                         return -ENOMEM;
1201
1202                 convert_delimiter(cifs_sb->prepath, CIFS_DIR_SEP(cifs_sb));
1203         } else
1204                 cifs_sb->prepath = NULL;
1205
1206         cifs_sb->mnt_cifs_flags |= CIFS_MOUNT_USE_PREFIX_PATH;
1207         return 0;
1208 }
1209
1210 /*
1211  * Handle weird Windows SMB server behaviour. It responds with
1212  * STATUS_OBJECT_NAME_INVALID code to SMB2 QUERY_INFO request for
1213  * "\<server>\<dfsname>\<linkpath>" DFS reference, where <dfsname> contains
1214  * non-ASCII unicode symbols.
1215  */
1216 int cifs_inval_name_dfs_link_error(const unsigned int xid,
1217                                    struct cifs_tcon *tcon,
1218                                    struct cifs_sb_info *cifs_sb,
1219                                    const char *full_path,
1220                                    bool *islink)
1221 {
1222         struct cifs_ses *ses = tcon->ses;
1223         size_t len;
1224         char *path;
1225         char *ref_path;
1226
1227         *islink = false;
1228
1229         /*
1230          * Fast path - skip check when @full_path doesn't have a prefix path to
1231          * look up or tcon is not DFS.
1232          */
1233         if (strlen(full_path) < 2 || !cifs_sb ||
1234             (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_DFS) ||
1235             !is_tcon_dfs(tcon) || !ses->server->origin_fullpath)
1236                 return 0;
1237
1238         /*
1239          * Slow path - tcon is DFS and @full_path has prefix path, so attempt
1240          * to get a referral to figure out whether it is an DFS link.
1241          */
1242         len = strnlen(tcon->tree_name, MAX_TREE_SIZE + 1) + strlen(full_path) + 1;
1243         path = kmalloc(len, GFP_KERNEL);
1244         if (!path)
1245                 return -ENOMEM;
1246
1247         scnprintf(path, len, "%s%s", tcon->tree_name, full_path);
1248         ref_path = dfs_cache_canonical_path(path + 1, cifs_sb->local_nls,
1249                                             cifs_remap(cifs_sb));
1250         kfree(path);
1251
1252         if (IS_ERR(ref_path)) {
1253                 if (PTR_ERR(ref_path) != -EINVAL)
1254                         return PTR_ERR(ref_path);
1255         } else {
1256                 struct dfs_info3_param *refs = NULL;
1257                 int num_refs = 0;
1258
1259                 /*
1260                  * XXX: we are not using dfs_cache_find() here because we might
1261                  * end filling all the DFS cache and thus potentially
1262                  * removing cached DFS targets that the client would eventually
1263                  * need during failover.
1264                  */
1265                 ses = CIFS_DFS_ROOT_SES(ses);
1266                 if (ses->server->ops->get_dfs_refer &&
1267                     !ses->server->ops->get_dfs_refer(xid, ses, ref_path, &refs,
1268                                                      &num_refs, cifs_sb->local_nls,
1269                                                      cifs_remap(cifs_sb)))
1270                         *islink = refs[0].server_type == DFS_TYPE_LINK;
1271                 free_dfs_info_array(refs, num_refs);
1272                 kfree(ref_path);
1273         }
1274         return 0;
1275 }
1276 #endif
1277
1278 int cifs_wait_for_server_reconnect(struct TCP_Server_Info *server, bool retry)
1279 {
1280         int timeout = 10;
1281         int rc;
1282
1283         spin_lock(&server->srv_lock);
1284         if (server->tcpStatus != CifsNeedReconnect) {
1285                 spin_unlock(&server->srv_lock);
1286                 return 0;
1287         }
1288         timeout *= server->nr_targets;
1289         spin_unlock(&server->srv_lock);
1290
1291         /*
1292          * Give demultiplex thread up to 10 seconds to each target available for
1293          * reconnect -- should be greater than cifs socket timeout which is 7
1294          * seconds.
1295          *
1296          * On "soft" mounts we wait once. Hard mounts keep retrying until
1297          * process is killed or server comes back on-line.
1298          */
1299         do {
1300                 rc = wait_event_interruptible_timeout(server->response_q,
1301                                                       (server->tcpStatus != CifsNeedReconnect),
1302                                                       timeout * HZ);
1303                 if (rc < 0) {
1304                         cifs_dbg(FYI, "%s: aborting reconnect due to received signal\n",
1305                                  __func__);
1306                         return -ERESTARTSYS;
1307                 }
1308
1309                 /* are we still trying to reconnect? */
1310                 spin_lock(&server->srv_lock);
1311                 if (server->tcpStatus != CifsNeedReconnect) {
1312                         spin_unlock(&server->srv_lock);
1313                         return 0;
1314                 }
1315                 spin_unlock(&server->srv_lock);
1316         } while (retry);
1317
1318         cifs_dbg(FYI, "%s: gave up waiting on reconnect\n", __func__);
1319         return -EHOSTDOWN;
1320 }