fs/cifs/misc.c

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