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->status = CifsNew;
  73                 ++ret_buf->ses_count;
  74                 INIT_LIST_HEAD(&ret_buf->smb_ses_list);
  75                 INIT_LIST_HEAD(&ret_buf->tcon_list);
  76                 mutex_init(&ret_buf->session_mutex);
  77                 spin_lock_init(&ret_buf->iface_lock);
  78                 spin_lock_init(&ret_buf->chan_lock);
  79         }
  80         return ret_buf;
  81 }
  82
  83 void
  84 sesInfoFree(struct cifs_ses *buf_to_free)
  85 {
  86         if (buf_to_free == NULL) {
  87                 cifs_dbg(FYI, "Null buffer passed to sesInfoFree\n");
  88                 return;
  89         }
  90
  91         atomic_dec(&sesInfoAllocCount);
  92         kfree(buf_to_free->serverOS);
  93         kfree(buf_to_free->serverDomain);
  94         kfree(buf_to_free->serverNOS);
  95         kfree_sensitive(buf_to_free->password);
  96         kfree(buf_to_free->user_name);
  97         kfree(buf_to_free->domainName);
  98         kfree_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
 117         atomic_inc(&tconInfoAllocCount);
 118         ret_buf->tidStatus = CifsNew;
 119         ++ret_buf->tc_count;
 120         INIT_LIST_HEAD(&ret_buf->openFileList);
 121         INIT_LIST_HEAD(&ret_buf->tcon_list);
 122         spin_lock_init(&ret_buf->open_file_lock);
 123         mutex_init(&ret_buf->crfid.fid_mutex);
 124         spin_lock_init(&ret_buf->stat_lock);
 125         atomic_set(&ret_buf->num_local_opens, 0);
 126         atomic_set(&ret_buf->num_remote_opens, 0);
 127
 128         return ret_buf;
 129 }
 130
 131 void
 132 tconInfoFree(struct cifs_tcon *buf_to_free)
 133 {
 134         if (buf_to_free == NULL) {
 135                 cifs_dbg(FYI, "Null buffer passed to tconInfoFree\n");
 136                 return;
 137         }
 138         atomic_dec(&tconInfoAllocCount);
 139         kfree(buf_to_free->nativeFileSystem);
 140         kfree_sensitive(buf_to_free->password);
 141         kfree(buf_to_free->crfid.fid);
 142         kfree(buf_to_free);
 143 }
 144
 145 struct smb_hdr *
 146 cifs_buf_get(void)
 147 {
 148         struct smb_hdr *ret_buf = NULL;
 149         /*
 150          * SMB2 header is bigger than CIFS one - no problems to clean some
 151          * more bytes for CIFS.
 152          */
 153         size_t buf_size = sizeof(struct smb2_sync_hdr);
 154
 155         /*
 156          * We could use negotiated size instead of max_msgsize -
 157          * but it may be more efficient to always alloc same size
 158          * albeit slightly larger than necessary and maxbuffersize
 159          * defaults to this and can not be bigger.
 160          */
 161         ret_buf = mempool_alloc(cifs_req_poolp, GFP_NOFS);
 162
 163         /* clear the first few header bytes */
 164         /* for most paths, more is cleared in header_assemble */
 165         memset(ret_buf, 0, buf_size + 3);
 166         atomic_inc(&bufAllocCount);
 167 #ifdef CONFIG_CIFS_STATS2
 168         atomic_inc(&totBufAllocCount);
 169 #endif /* CONFIG_CIFS_STATS2 */
 170
 171         return ret_buf;
 172 }
 173
 174 void
 175 cifs_buf_release(void *buf_to_free)
 176 {
 177         if (buf_to_free == NULL) {
 178                 /* cifs_dbg(FYI, "Null buffer passed to cifs_buf_release\n");*/
 179                 return;
 180         }
 181         mempool_free(buf_to_free, cifs_req_poolp);
 182
 183         atomic_dec(&bufAllocCount);
 184         return;
 185 }
 186
 187 struct smb_hdr *
 188 cifs_small_buf_get(void)
 189 {
 190         struct smb_hdr *ret_buf = NULL;
 191
 192 /* We could use negotiated size instead of max_msgsize -
 193    but it may be more efficient to always alloc same size
 194    albeit slightly larger than necessary and maxbuffersize
 195    defaults to this and can not be bigger */
 196         ret_buf = mempool_alloc(cifs_sm_req_poolp, GFP_NOFS);
 197         /* No need to clear memory here, cleared in header assemble */
 198         /*      memset(ret_buf, 0, sizeof(struct smb_hdr) + 27);*/
 199         atomic_inc(&smBufAllocCount);
 200 #ifdef CONFIG_CIFS_STATS2
 201         atomic_inc(&totSmBufAllocCount);
 202 #endif /* CONFIG_CIFS_STATS2 */
 203
 204         return ret_buf;
 205 }
 206
 207 void
 208 cifs_small_buf_release(void *buf_to_free)
 209 {
 210
 211         if (buf_to_free == NULL) {
 212                 cifs_dbg(FYI, "Null buffer passed to cifs_small_buf_release\n");
 213                 return;
 214         }
 215         mempool_free(buf_to_free, cifs_sm_req_poolp);
 216
 217         atomic_dec(&smBufAllocCount);
 218         return;
 219 }
 220
 221 void
 222 free_rsp_buf(int resp_buftype, void *rsp)
 223 {
 224         if (resp_buftype == CIFS_SMALL_BUFFER)
 225                 cifs_small_buf_release(rsp);
 226         else if (resp_buftype == CIFS_LARGE_BUFFER)
 227                 cifs_buf_release(rsp);
 228 }
 229
 230 /* NB: MID can not be set if treeCon not passed in, in that
 231    case it is responsbility of caller to set the mid */
 232 void
 233 header_assemble(struct smb_hdr *buffer, char smb_command /* command */ ,
 234                 const struct cifs_tcon *treeCon, int word_count
 235                 /* length of fixed section (word count) in two byte units  */)
 236 {
 237         char *temp = (char *) buffer;
 238
 239         memset(temp, 0, 256); /* bigger than MAX_CIFS_HDR_SIZE */
 240
 241         buffer->smb_buf_length = cpu_to_be32(
 242             (2 * word_count) + sizeof(struct smb_hdr) -
 243             4 /*  RFC 1001 length field does not count */  +
 244             2 /* for bcc field itself */) ;
 245
 246         buffer->Protocol[0] = 0xFF;
 247         buffer->Protocol[1] = 'S';
 248         buffer->Protocol[2] = 'M';
 249         buffer->Protocol[3] = 'B';
 250         buffer->Command = smb_command;
 251         buffer->Flags = 0x00;   /* case sensitive */
 252         buffer->Flags2 = SMBFLG2_KNOWS_LONG_NAMES;
 253         buffer->Pid = cpu_to_le16((__u16)current->tgid);
 254         buffer->PidHigh = cpu_to_le16((__u16)(current->tgid >> 16));
 255         if (treeCon) {
 256                 buffer->Tid = treeCon->tid;
 257                 if (treeCon->ses) {
 258                         if (treeCon->ses->capabilities & CAP_UNICODE)
 259                                 buffer->Flags2 |= SMBFLG2_UNICODE;
 260                         if (treeCon->ses->capabilities & CAP_STATUS32)
 261                                 buffer->Flags2 |= SMBFLG2_ERR_STATUS;
 262
 263                         /* Uid is not converted */
 264                         buffer->Uid = treeCon->ses->Suid;
 265                         if (treeCon->ses->server)
 266                                 buffer->Mid = get_next_mid(treeCon->ses->server);
 267                 }
 268                 if (treeCon->Flags & SMB_SHARE_IS_IN_DFS)
 269                         buffer->Flags2 |= SMBFLG2_DFS;
 270                 if (treeCon->nocase)
 271                         buffer->Flags  |= SMBFLG_CASELESS;
 272                 if ((treeCon->ses) && (treeCon->ses->server))
 273                         if (treeCon->ses->server->sign)
 274                                 buffer->Flags2 |= SMBFLG2_SECURITY_SIGNATURE;
 275         }
 276
 277 /*  endian conversion of flags is now done just before sending */
 278         buffer->WordCount = (char) word_count;
 279         return;
 280 }
 281
 282 static int
 283 check_smb_hdr(struct smb_hdr *smb)
 284 {
 285         /* does it have the right SMB "signature" ? */
 286         if (*(__le32 *) smb->Protocol != cpu_to_le32(0x424d53ff)) {
 287                 cifs_dbg(VFS, "Bad protocol string signature header 0x%x\n",
 288                          *(unsigned int *)smb->Protocol);
 289                 return 1;
 290         }
 291
 292         /* if it's a response then accept */
 293         if (smb->Flags & SMBFLG_RESPONSE)
 294                 return 0;
 295
 296         /* only one valid case where server sends us request */
 297         if (smb->Command == SMB_COM_LOCKING_ANDX)
 298                 return 0;
 299
 300         cifs_dbg(VFS, "Server sent request, not response. mid=%u\n",
 301                  get_mid(smb));
 302         return 1;
 303 }
 304
 305 int
 306 checkSMB(char *buf, unsigned int total_read, struct TCP_Server_Info *server)
 307 {
 308         struct smb_hdr *smb = (struct smb_hdr *)buf;
 309         __u32 rfclen = be32_to_cpu(smb->smb_buf_length);
 310         __u32 clc_len;  /* calculated length */
 311         cifs_dbg(FYI, "checkSMB Length: 0x%x, smb_buf_length: 0x%x\n",
 312                  total_read, rfclen);
 313
 314         /* is this frame too small to even get to a BCC? */
 315         if (total_read < 2 + sizeof(struct smb_hdr)) {
 316                 if ((total_read >= sizeof(struct smb_hdr) - 1)
 317                             && (smb->Status.CifsError != 0)) {
 318                         /* it's an error return */
 319                         smb->WordCount = 0;
 320                         /* some error cases do not return wct and bcc */
 321                         return 0;
 322                 } else if ((total_read == sizeof(struct smb_hdr) + 1) &&
 323                                 (smb->WordCount == 0)) {
 324                         char *tmp = (char *)smb;
 325                         /* Need to work around a bug in two servers here */
 326                         /* First, check if the part of bcc they sent was zero */
 327                         if (tmp[sizeof(struct smb_hdr)] == 0) {
 328                                 /* some servers return only half of bcc
 329                                  * on simple responses (wct, bcc both zero)
 330                                  * in particular have seen this on
 331                                  * ulogoffX and FindClose. This leaves
 332                                  * one byte of bcc potentially unitialized
 333                                  */
 334                                 /* zero rest of bcc */
 335                                 tmp[sizeof(struct smb_hdr)+1] = 0;
 336                                 return 0;
 337                         }
 338                         cifs_dbg(VFS, "rcvd invalid byte count (bcc)\n");
 339                 } else {
 340                         cifs_dbg(VFS, "Length less than smb header size\n");
 341                 }
 342                 return -EIO;
 343         }
 344
 345         /* otherwise, there is enough to get to the BCC */
 346         if (check_smb_hdr(smb))
 347                 return -EIO;
 348         clc_len = smbCalcSize(smb, server);
 349
 350         if (4 + rfclen != total_read) {
 351                 cifs_dbg(VFS, "Length read does not match RFC1001 length %d\n",
 352                          rfclen);
 353                 return -EIO;
 354         }
 355
 356         if (4 + rfclen != clc_len) {
 357                 __u16 mid = get_mid(smb);
 358                 /* check if bcc wrapped around for large read responses */
 359                 if ((rfclen > 64 * 1024) && (rfclen > clc_len)) {
 360                         /* check if lengths match mod 64K */
 361                         if (((4 + rfclen) & 0xFFFF) == (clc_len & 0xFFFF))
 362                                 return 0; /* bcc wrapped */
 363                 }
 364                 cifs_dbg(FYI, "Calculated size %u vs length %u mismatch for mid=%u\n",
 365                          clc_len, 4 + rfclen, mid);
 366
 367                 if (4 + rfclen < clc_len) {
 368                         cifs_dbg(VFS, "RFC1001 size %u smaller than SMB for mid=%u\n",
 369                                  rfclen, mid);
 370                         return -EIO;
 371                 } else if (rfclen > clc_len + 512) {
 372                         /*
 373                          * Some servers (Windows XP in particular) send more
 374                          * data than the lengths in the SMB packet would
 375                          * indicate on certain calls (byte range locks and
 376                          * trans2 find first calls in particular). While the
 377                          * client can handle such a frame by ignoring the
 378                          * trailing data, we choose limit the amount of extra
 379                          * data to 512 bytes.
 380                          */
 381                         cifs_dbg(VFS, "RFC1001 size %u more than 512 bytes larger than SMB for mid=%u\n",
 382                                  rfclen, mid);
 383                         return -EIO;
 384                 }
 385         }
 386         return 0;
 387 }
 388
 389 bool
 390 is_valid_oplock_break(char *buffer, struct TCP_Server_Info *srv)
 391 {
 392         struct smb_hdr *buf = (struct smb_hdr *)buffer;
 393         struct smb_com_lock_req *pSMB = (struct smb_com_lock_req *)buf;
 394         struct list_head *tmp, *tmp1, *tmp2;
 395         struct cifs_ses *ses;
 396         struct cifs_tcon *tcon;
 397         struct cifsInodeInfo *pCifsInode;
 398         struct cifsFileInfo *netfile;
 399
 400         cifs_dbg(FYI, "Checking for oplock break or dnotify response\n");
 401         if ((pSMB->hdr.Command == SMB_COM_NT_TRANSACT) &&
 402            (pSMB->hdr.Flags & SMBFLG_RESPONSE)) {
 403                 struct smb_com_transaction_change_notify_rsp *pSMBr =
 404                         (struct smb_com_transaction_change_notify_rsp *)buf;
 405                 struct file_notify_information *pnotify;
 406                 __u32 data_offset = 0;
 407                 size_t len = srv->total_read - sizeof(pSMBr->hdr.smb_buf_length);
 408
 409                 if (get_bcc(buf) > sizeof(struct file_notify_information)) {
 410                         data_offset = le32_to_cpu(pSMBr->DataOffset);
 411
 412                         if (data_offset >
 413                             len - sizeof(struct file_notify_information)) {
 414                                 cifs_dbg(FYI, "Invalid data_offset %u\n",
 415                                          data_offset);
 416                                 return true;
 417                         }
 418                         pnotify = (struct file_notify_information *)
 419                                 ((char *)&pSMBr->hdr.Protocol + data_offset);
 420                         cifs_dbg(FYI, "dnotify on %s Action: 0x%x\n",
 421                                  pnotify->FileName, pnotify->Action);
 422                         /*   cifs_dump_mem("Rcvd notify Data: ",buf,
 423                                 sizeof(struct smb_hdr)+60); */
 424                         return true;
 425                 }
 426                 if (pSMBr->hdr.Status.CifsError) {
 427                         cifs_dbg(FYI, "notify err 0x%x\n",
 428                                  pSMBr->hdr.Status.CifsError);
 429                         return true;
 430                 }
 431                 return false;
 432         }
 433         if (pSMB->hdr.Command != SMB_COM_LOCKING_ANDX)
 434                 return false;
 435         if (pSMB->hdr.Flags & SMBFLG_RESPONSE) {
 436                 /* no sense logging error on invalid handle on oplock
 437                    break - harmless race between close request and oplock
 438                    break response is expected from time to time writing out
 439                    large dirty files cached on the client */
 440                 if ((NT_STATUS_INVALID_HANDLE) ==
 441                    le32_to_cpu(pSMB->hdr.Status.CifsError)) {
 442                         cifs_dbg(FYI, "Invalid handle on oplock break\n");
 443                         return true;
 444                 } else if (ERRbadfid ==
 445                    le16_to_cpu(pSMB->hdr.Status.DosError.Error)) {
 446                         return true;
 447                 } else {
 448                         return false; /* on valid oplock brk we get "request" */
 449                 }
 450         }
 451         if (pSMB->hdr.WordCount != 8)
 452                 return false;
 453
 454         cifs_dbg(FYI, "oplock type 0x%x level 0x%x\n",
 455                  pSMB->LockType, pSMB->OplockLevel);
 456         if (!(pSMB->LockType & LOCKING_ANDX_OPLOCK_RELEASE))
 457                 return false;
 458
 459         /* look up tcon based on tid & uid */
 460         spin_lock(&cifs_tcp_ses_lock);
 461         list_for_each(tmp, &srv->smb_ses_list) {
 462                 ses = list_entry(tmp, struct cifs_ses, smb_ses_list);
 463                 list_for_each(tmp1, &ses->tcon_list) {
 464                         tcon = list_entry(tmp1, struct cifs_tcon, tcon_list);
 465                         if (tcon->tid != buf->Tid)
 466                                 continue;
 467
 468                         cifs_stats_inc(&tcon->stats.cifs_stats.num_oplock_brks);
 469                         spin_lock(&tcon->open_file_lock);
 470                         list_for_each(tmp2, &tcon->openFileList) {
 471                                 netfile = list_entry(tmp2, struct cifsFileInfo,
 472                                                      tlist);
 473                                 if (pSMB->Fid != netfile->fid.netfid)
 474                                         continue;
 475
 476                                 cifs_dbg(FYI, "file id match, oplock break\n");
 477                                 pCifsInode = CIFS_I(d_inode(netfile->dentry));
 478
 479                                 set_bit(CIFS_INODE_PENDING_OPLOCK_BREAK,
 480                                         &pCifsInode->flags);
 481
 482                                 netfile->oplock_epoch = 0;
 483                                 netfile->oplock_level = pSMB->OplockLevel;
 484                                 netfile->oplock_break_cancelled = false;
 485                                 cifs_queue_oplock_break(netfile);
 486
 487                                 spin_unlock(&tcon->open_file_lock);
 488                                 spin_unlock(&cifs_tcp_ses_lock);
 489                                 return true;
 490                         }
 491                         spin_unlock(&tcon->open_file_lock);
 492                         spin_unlock(&cifs_tcp_ses_lock);
 493                         cifs_dbg(FYI, "No matching file for oplock break\n");
 494                         return true;
 495                 }
 496         }
 497         spin_unlock(&cifs_tcp_ses_lock);
 498         cifs_dbg(FYI, "Can not process oplock break for non-existent connection\n");
 499         return true;
 500 }
 501
 502 void
 503 dump_smb(void *buf, int smb_buf_length)
 504 {
 505         if (traceSMB == 0)
 506                 return;
 507
 508         print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_NONE, 8, 2, buf,
 509                        smb_buf_length, true);
 510 }
 511
 512 void
 513 cifs_autodisable_serverino(struct cifs_sb_info *cifs_sb)
 514 {
 515         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SERVER_INUM) {
 516                 struct cifs_tcon *tcon = NULL;
 517
 518                 if (cifs_sb->master_tlink)
 519                         tcon = cifs_sb_master_tcon(cifs_sb);
 520
 521                 cifs_sb->mnt_cifs_flags &= ~CIFS_MOUNT_SERVER_INUM;
 522                 cifs_sb->mnt_cifs_serverino_autodisabled = true;
 523                 cifs_dbg(VFS, "Autodisabling the use of server inode numbers on %s\n",
 524                          tcon ? tcon->treeName : "new server");
 525                 cifs_dbg(VFS, "The server doesn't seem to support them properly or the files might be on different servers (DFS)\n");
 526                 cifs_dbg(VFS, "Hardlinks will not be recognized on this mount. Consider mounting with the \"noserverino\" option to silence this message.\n");
 527
 528         }
 529 }
 530
 531 void cifs_set_oplock_level(struct cifsInodeInfo *cinode, __u32 oplock)
 532 {
 533         oplock &= 0xF;
 534
 535         if (oplock == OPLOCK_EXCLUSIVE) {
 536                 cinode->oplock = CIFS_CACHE_WRITE_FLG | CIFS_CACHE_READ_FLG;
 537                 cifs_dbg(FYI, "Exclusive Oplock granted on inode %p\n",
 538                          &cinode->vfs_inode);
 539         } else if (oplock == OPLOCK_READ) {
 540                 cinode->oplock = CIFS_CACHE_READ_FLG;
 541                 cifs_dbg(FYI, "Level II Oplock granted on inode %p\n",
 542                          &cinode->vfs_inode);
 543         } else
 544                 cinode->oplock = 0;
 545 }
 546
 547 /*
 548  * We wait for oplock breaks to be processed before we attempt to perform
 549  * writes.
 550  */
 551 int cifs_get_writer(struct cifsInodeInfo *cinode)
 552 {
 553         int rc;
 554
 555 start:
 556         rc = wait_on_bit(&cinode->flags, CIFS_INODE_PENDING_OPLOCK_BREAK,
 557                          TASK_KILLABLE);
 558         if (rc)
 559                 return rc;
 560
 561         spin_lock(&cinode->writers_lock);
 562         if (!cinode->writers)
 563                 set_bit(CIFS_INODE_PENDING_WRITERS, &cinode->flags);
 564         cinode->writers++;
 565         /* Check to see if we have started servicing an oplock break */
 566         if (test_bit(CIFS_INODE_PENDING_OPLOCK_BREAK, &cinode->flags)) {
 567                 cinode->writers--;
 568                 if (cinode->writers == 0) {
 569                         clear_bit(CIFS_INODE_PENDING_WRITERS, &cinode->flags);
 570                         wake_up_bit(&cinode->flags, CIFS_INODE_PENDING_WRITERS);
 571                 }
 572                 spin_unlock(&cinode->writers_lock);
 573                 goto start;
 574         }
 575         spin_unlock(&cinode->writers_lock);
 576         return 0;
 577 }
 578
 579 void cifs_put_writer(struct cifsInodeInfo *cinode)
 580 {
 581         spin_lock(&cinode->writers_lock);
 582         cinode->writers--;
 583         if (cinode->writers == 0) {
 584                 clear_bit(CIFS_INODE_PENDING_WRITERS, &cinode->flags);
 585                 wake_up_bit(&cinode->flags, CIFS_INODE_PENDING_WRITERS);
 586         }
 587         spin_unlock(&cinode->writers_lock);
 588 }
 589
 590 /**
 591  * cifs_queue_oplock_break - queue the oplock break handler for cfile
 592  * @cfile: The file to break the oplock on
 593  *
 594  * This function is called from the demultiplex thread when it
 595  * receives an oplock break for @cfile.
 596  *
 597  * Assumes the tcon->open_file_lock is held.
 598  * Assumes cfile->file_info_lock is NOT held.
 599  */
 600 void cifs_queue_oplock_break(struct cifsFileInfo *cfile)
 601 {
 602         /*
 603          * Bump the handle refcount now while we hold the
 604          * open_file_lock to enforce the validity of it for the oplock
 605          * break handler. The matching put is done at the end of the
 606          * handler.
 607          */
 608         cifsFileInfo_get(cfile);
 609
 610         queue_work(cifsoplockd_wq, &cfile->oplock_break);
 611 }
 612
 613 void cifs_done_oplock_break(struct cifsInodeInfo *cinode)
 614 {
 615         clear_bit(CIFS_INODE_PENDING_OPLOCK_BREAK, &cinode->flags);
 616         wake_up_bit(&cinode->flags, CIFS_INODE_PENDING_OPLOCK_BREAK);
 617 }
 618
 619 bool
 620 backup_cred(struct cifs_sb_info *cifs_sb)
 621 {
 622         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_BACKUPUID) {
 623                 if (uid_eq(cifs_sb->ctx->backupuid, current_fsuid()))
 624                         return true;
 625         }
 626         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_BACKUPGID) {
 627                 if (in_group_p(cifs_sb->ctx->backupgid))
 628                         return true;
 629         }
 630
 631         return false;
 632 }
 633
 634 void
 635 cifs_del_pending_open(struct cifs_pending_open *open)
 636 {
 637         spin_lock(&tlink_tcon(open->tlink)->open_file_lock);
 638         list_del(&open->olist);
 639         spin_unlock(&tlink_tcon(open->tlink)->open_file_lock);
 640 }
 641
 642 void
 643 cifs_add_pending_open_locked(struct cifs_fid *fid, struct tcon_link *tlink,
 644                              struct cifs_pending_open *open)
 645 {
 646         memcpy(open->lease_key, fid->lease_key, SMB2_LEASE_KEY_SIZE);
 647         open->oplock = CIFS_OPLOCK_NO_CHANGE;
 648         open->tlink = tlink;
 649         fid->pending_open = open;
 650         list_add_tail(&open->olist, &tlink_tcon(tlink)->pending_opens);
 651 }
 652
 653 void
 654 cifs_add_pending_open(struct cifs_fid *fid, struct tcon_link *tlink,
 655                       struct cifs_pending_open *open)
 656 {
 657         spin_lock(&tlink_tcon(tlink)->open_file_lock);
 658         cifs_add_pending_open_locked(fid, tlink, open);
 659         spin_unlock(&tlink_tcon(open->tlink)->open_file_lock);
 660 }
 661
 662 /*
 663  * Critical section which runs after acquiring deferred_lock.
 664  * As there is no reference count on cifs_deferred_close, pdclose
 665  * should not be used outside deferred_lock.
 666  */
 667 bool
 668 cifs_is_deferred_close(struct cifsFileInfo *cfile, struct cifs_deferred_close **pdclose)
 669 {
 670         struct cifs_deferred_close *dclose;
 671
 672         list_for_each_entry(dclose, &CIFS_I(d_inode(cfile->dentry))->deferred_closes, dlist) {
 673                 if ((dclose->netfid == cfile->fid.netfid) &&
 674                         (dclose->persistent_fid == cfile->fid.persistent_fid) &&
 675                         (dclose->volatile_fid == cfile->fid.volatile_fid)) {
 676                         *pdclose = dclose;
 677                         return true;
 678                 }
 679         }
 680         return false;
 681 }
 682
 683 /*
 684  * Critical section which runs after acquiring deferred_lock.
 685  */
 686 void
 687 cifs_add_deferred_close(struct cifsFileInfo *cfile, struct cifs_deferred_close *dclose)
 688 {
 689         bool is_deferred = false;
 690         struct cifs_deferred_close *pdclose;
 691
 692         is_deferred = cifs_is_deferred_close(cfile, &pdclose);
 693         if (is_deferred) {
 694                 kfree(dclose);
 695                 return;
 696         }
 697
 698         dclose->tlink = cfile->tlink;
 699         dclose->netfid = cfile->fid.netfid;
 700         dclose->persistent_fid = cfile->fid.persistent_fid;
 701         dclose->volatile_fid = cfile->fid.volatile_fid;
 702         list_add_tail(&dclose->dlist, &CIFS_I(d_inode(cfile->dentry))->deferred_closes);
 703 }
 704
 705 /*
 706  * Critical section which runs after acquiring deferred_lock.
 707  */
 708 void
 709 cifs_del_deferred_close(struct cifsFileInfo *cfile)
 710 {
 711         bool is_deferred = false;
 712         struct cifs_deferred_close *dclose;
 713
 714         is_deferred = cifs_is_deferred_close(cfile, &dclose);
 715         if (!is_deferred)
 716                 return;
 717         list_del(&dclose->dlist);
 718         kfree(dclose);
 719 }
 720
 721 void
 722 cifs_close_deferred_file(struct cifsInodeInfo *cifs_inode)
 723 {
 724         struct cifsFileInfo *cfile = NULL;
 725         struct file_list *tmp_list, *tmp_next_list;
 726         struct list_head file_head;
 727
 728         if (cifs_inode == NULL)
 729                 return;
 730
 731         INIT_LIST_HEAD(&file_head);
 732         spin_lock(&cifs_inode->open_file_lock);
 733         list_for_each_entry(cfile, &cifs_inode->openFileList, flist) {
 734                 if (delayed_work_pending(&cfile->deferred)) {
 735                         if (cancel_delayed_work(&cfile->deferred)) {
 736                                 spin_lock(&cifs_inode->deferred_lock);
 737                                 cifs_del_deferred_close(cfile);
 738                                 spin_unlock(&cifs_inode->deferred_lock);
 739
 740                                 tmp_list = kmalloc(sizeof(struct file_list), GFP_ATOMIC);
 741                                 if (tmp_list == NULL)
 742                                         break;
 743                                 tmp_list->cfile = cfile;
 744                                 list_add_tail(&tmp_list->list, &file_head);
 745                         }
 746                 }
 747         }
 748         spin_unlock(&cifs_inode->open_file_lock);
 749
 750         list_for_each_entry_safe(tmp_list, tmp_next_list, &file_head, list) {
 751                 _cifsFileInfo_put(tmp_list->cfile, false, false);
 752                 list_del(&tmp_list->list);
 753                 kfree(tmp_list);
 754         }
 755 }
 756
 757 void
 758 cifs_close_all_deferred_files(struct cifs_tcon *tcon)
 759 {
 760         struct cifsFileInfo *cfile;
 761         struct list_head *tmp;
 762         struct file_list *tmp_list, *tmp_next_list;
 763         struct list_head file_head;
 764
 765         INIT_LIST_HEAD(&file_head);
 766         spin_lock(&tcon->open_file_lock);
 767         list_for_each(tmp, &tcon->openFileList) {
 768                 cfile = list_entry(tmp, struct cifsFileInfo, tlist);
 769                 if (delayed_work_pending(&cfile->deferred)) {
 770                         if (cancel_delayed_work(&cfile->deferred)) {
 771                                 spin_lock(&CIFS_I(d_inode(cfile->dentry))->deferred_lock);
 772                                 cifs_del_deferred_close(cfile);
 773                                 spin_unlock(&CIFS_I(d_inode(cfile->dentry))->deferred_lock);
 774
 775                                 tmp_list = kmalloc(sizeof(struct file_list), GFP_ATOMIC);
 776                                 if (tmp_list == NULL)
 777                                         break;
 778                                 tmp_list->cfile = cfile;
 779                                 list_add_tail(&tmp_list->list, &file_head);
 780                         }
 781                 }
 782         }
 783         spin_unlock(&tcon->open_file_lock);
 784
 785         list_for_each_entry_safe(tmp_list, tmp_next_list, &file_head, list) {
 786                 _cifsFileInfo_put(tmp_list->cfile, true, false);
 787                 list_del(&tmp_list->list);
 788                 kfree(tmp_list);
 789         }
 790 }
 791 void
 792 cifs_close_deferred_file_under_dentry(struct cifs_tcon *tcon, const char *path)
 793 {
 794         struct cifsFileInfo *cfile;
 795         struct list_head *tmp;
 796         struct file_list *tmp_list, *tmp_next_list;
 797         struct list_head file_head;
 798         void *page;
 799         const char *full_path;
 800
 801         INIT_LIST_HEAD(&file_head);
 802         page = alloc_dentry_path();
 803         spin_lock(&tcon->open_file_lock);
 804         list_for_each(tmp, &tcon->openFileList) {
 805                 cfile = list_entry(tmp, struct cifsFileInfo, tlist);
 806                 full_path = build_path_from_dentry(cfile->dentry, page);
 807                 if (strstr(full_path, path)) {
 808                         if (delayed_work_pending(&cfile->deferred)) {
 809                                 if (cancel_delayed_work(&cfile->deferred)) {
 810                                         spin_lock(&CIFS_I(d_inode(cfile->dentry))->deferred_lock);
 811                                         cifs_del_deferred_close(cfile);
 812                                         spin_unlock(&CIFS_I(d_inode(cfile->dentry))->deferred_lock);
 813
 814                                         tmp_list = kmalloc(sizeof(struct file_list), GFP_ATOMIC);
 815                                         if (tmp_list == NULL)
 816                                                 break;
 817                                         tmp_list->cfile = cfile;
 818                                         list_add_tail(&tmp_list->list, &file_head);
 819                                 }
 820                         }
 821                 }
 822         }
 823         spin_unlock(&tcon->open_file_lock);
 824
 825         list_for_each_entry_safe(tmp_list, tmp_next_list, &file_head, list) {
 826                 _cifsFileInfo_put(tmp_list->cfile, true, false);
 827                 list_del(&tmp_list->list);
 828                 kfree(tmp_list);
 829         }
 830         free_dentry_path(page);
 831 }
 832
 833 /* parses DFS refferal V3 structure
 834  * caller is responsible for freeing target_nodes
 835  * returns:
 836  * - on success - 0
 837  * - on failure - errno
 838  */
 839 int
 840 parse_dfs_referrals(struct get_dfs_referral_rsp *rsp, u32 rsp_size,
 841                     unsigned int *num_of_nodes,
 842                     struct dfs_info3_param **target_nodes,
 843                     const struct nls_table *nls_codepage, int remap,
 844                     const char *searchName, bool is_unicode)
 845 {
 846         int i, rc = 0;
 847         char *data_end;
 848         struct dfs_referral_level_3 *ref;
 849
 850         *num_of_nodes = le16_to_cpu(rsp->NumberOfReferrals);
 851
 852         if (*num_of_nodes < 1) {
 853                 cifs_dbg(VFS, "num_referrals: must be at least > 0, but we get num_referrals = %d\n",
 854                          *num_of_nodes);
 855                 rc = -EINVAL;
 856                 goto parse_DFS_referrals_exit;
 857         }
 858
 859         ref = (struct dfs_referral_level_3 *) &(rsp->referrals);
 860         if (ref->VersionNumber != cpu_to_le16(3)) {
 861                 cifs_dbg(VFS, "Referrals of V%d version are not supported, should be V3\n",
 862                          le16_to_cpu(ref->VersionNumber));
 863                 rc = -EINVAL;
 864                 goto parse_DFS_referrals_exit;
 865         }
 866
 867         /* get the upper boundary of the resp buffer */
 868         data_end = (char *)rsp + rsp_size;
 869
 870         cifs_dbg(FYI, "num_referrals: %d dfs flags: 0x%x ...\n",
 871                  *num_of_nodes, le32_to_cpu(rsp->DFSFlags));
 872
 873         *target_nodes = kcalloc(*num_of_nodes, sizeof(struct dfs_info3_param),
 874                                 GFP_KERNEL);
 875         if (*target_nodes == NULL) {
 876                 rc = -ENOMEM;
 877                 goto parse_DFS_referrals_exit;
 878         }
 879
 880         /* collect necessary data from referrals */
 881         for (i = 0; i < *num_of_nodes; i++) {
 882                 char *temp;
 883                 int max_len;
 884                 struct dfs_info3_param *node = (*target_nodes)+i;
 885
 886                 node->flags = le32_to_cpu(rsp->DFSFlags);
 887                 if (is_unicode) {
 888                         __le16 *tmp = kmalloc(strlen(searchName)*2 + 2,
 889                                                 GFP_KERNEL);
 890                         if (tmp == NULL) {
 891                                 rc = -ENOMEM;
 892                                 goto parse_DFS_referrals_exit;
 893                         }
 894                         cifsConvertToUTF16((__le16 *) tmp, searchName,
 895                                            PATH_MAX, nls_codepage, remap);
 896                         node->path_consumed = cifs_utf16_bytes(tmp,
 897                                         le16_to_cpu(rsp->PathConsumed),
 898                                         nls_codepage);
 899                         kfree(tmp);
 900                 } else
 901                         node->path_consumed = le16_to_cpu(rsp->PathConsumed);
 902
 903                 node->server_type = le16_to_cpu(ref->ServerType);
 904                 node->ref_flag = le16_to_cpu(ref->ReferralEntryFlags);
 905
 906                 /* copy DfsPath */
 907                 temp = (char *)ref + le16_to_cpu(ref->DfsPathOffset);
 908                 max_len = data_end - temp;
 909                 node->path_name = cifs_strndup_from_utf16(temp, max_len,
 910                                                 is_unicode, nls_codepage);
 911                 if (!node->path_name) {
 912                         rc = -ENOMEM;
 913                         goto parse_DFS_referrals_exit;
 914                 }
 915
 916                 /* copy link target UNC */
 917                 temp = (char *)ref + le16_to_cpu(ref->NetworkAddressOffset);
 918                 max_len = data_end - temp;
 919                 node->node_name = cifs_strndup_from_utf16(temp, max_len,
 920                                                 is_unicode, nls_codepage);
 921                 if (!node->node_name) {
 922                         rc = -ENOMEM;
 923                         goto parse_DFS_referrals_exit;
 924                 }
 925
 926                 node->ttl = le32_to_cpu(ref->TimeToLive);
 927
 928                 ref++;
 929         }
 930
 931 parse_DFS_referrals_exit:
 932         if (rc) {
 933                 free_dfs_info_array(*target_nodes, *num_of_nodes);
 934                 *target_nodes = NULL;
 935                 *num_of_nodes = 0;
 936         }
 937         return rc;
 938 }
 939
 940 struct cifs_aio_ctx *
 941 cifs_aio_ctx_alloc(void)
 942 {
 943         struct cifs_aio_ctx *ctx;
 944
 945         /*
 946          * Must use kzalloc to initialize ctx->bv to NULL and ctx->direct_io
 947          * to false so that we know when we have to unreference pages within
 948          * cifs_aio_ctx_release()
 949          */
 950         ctx = kzalloc(sizeof(struct cifs_aio_ctx), GFP_KERNEL);
 951         if (!ctx)
 952                 return NULL;
 953
 954         INIT_LIST_HEAD(&ctx->list);
 955         mutex_init(&ctx->aio_mutex);
 956         init_completion(&ctx->done);
 957         kref_init(&ctx->refcount);
 958         return ctx;
 959 }
 960
 961 void
 962 cifs_aio_ctx_release(struct kref *refcount)
 963 {
 964         struct cifs_aio_ctx *ctx = container_of(refcount,
 965                                         struct cifs_aio_ctx, refcount);
 966
 967         cifsFileInfo_put(ctx->cfile);
 968
 969         /*
 970          * ctx->bv is only set if setup_aio_ctx_iter() was call successfuly
 971          * which means that iov_iter_get_pages() was a success and thus that
 972          * we have taken reference on pages.
 973          */
 974         if (ctx->bv) {
 975                 unsigned i;
 976
 977                 for (i = 0; i < ctx->npages; i++) {
 978                         if (ctx->should_dirty)
 979                                 set_page_dirty(ctx->bv[i].bv_page);
 980                         put_page(ctx->bv[i].bv_page);
 981                 }
 982                 kvfree(ctx->bv);
 983         }
 984
 985         kfree(ctx);
 986 }
 987
 988 #define CIFS_AIO_KMALLOC_LIMIT (1024 * 1024)
 989
 990 int
 991 setup_aio_ctx_iter(struct cifs_aio_ctx *ctx, struct iov_iter *iter, int rw)
 992 {
 993         ssize_t rc;
 994         unsigned int cur_npages;
 995         unsigned int npages = 0;
 996         unsigned int i;
 997         size_t len;
 998         size_t count = iov_iter_count(iter);
 999         unsigned int saved_len;
1000         size_t start;
1001         unsigned int max_pages = iov_iter_npages(iter, INT_MAX);
1002         struct page **pages = NULL;
1003         struct bio_vec *bv = NULL;
1004
1005         if (iov_iter_is_kvec(iter)) {
1006                 memcpy(&ctx->iter, iter, sizeof(*iter));
1007                 ctx->len = count;
1008                 iov_iter_advance(iter, count);
1009                 return 0;
1010         }
1011
1012         if (array_size(max_pages, sizeof(*bv)) <= CIFS_AIO_KMALLOC_LIMIT)
1013                 bv = kmalloc_array(max_pages, sizeof(*bv), GFP_KERNEL);
1014
1015         if (!bv) {
1016                 bv = vmalloc(array_size(max_pages, sizeof(*bv)));
1017                 if (!bv)
1018                         return -ENOMEM;
1019         }
1020
1021         if (array_size(max_pages, sizeof(*pages)) <= CIFS_AIO_KMALLOC_LIMIT)
1022                 pages = kmalloc_array(max_pages, sizeof(*pages), GFP_KERNEL);
1023
1024         if (!pages) {
1025                 pages = vmalloc(array_size(max_pages, sizeof(*pages)));
1026                 if (!pages) {
1027                         kvfree(bv);
1028                         return -ENOMEM;
1029                 }
1030         }
1031
1032         saved_len = count;
1033
1034         while (count && npages < max_pages) {
1035                 rc = iov_iter_get_pages(iter, pages, count, max_pages, &start);
1036                 if (rc < 0) {
1037                         cifs_dbg(VFS, "Couldn't get user pages (rc=%zd)\n", rc);
1038                         break;
1039                 }
1040
1041                 if (rc > count) {
1042                         cifs_dbg(VFS, "get pages rc=%zd more than %zu\n", rc,
1043                                  count);
1044                         break;
1045                 }
1046
1047                 iov_iter_advance(iter, rc);
1048                 count -= rc;
1049                 rc += start;
1050                 cur_npages = DIV_ROUND_UP(rc, PAGE_SIZE);
1051
1052                 if (npages + cur_npages > max_pages) {
1053                         cifs_dbg(VFS, "out of vec array capacity (%u vs %u)\n",
1054                                  npages + cur_npages, max_pages);
1055                         break;
1056                 }
1057
1058                 for (i = 0; i < cur_npages; i++) {
1059                         len = rc > PAGE_SIZE ? PAGE_SIZE : rc;
1060                         bv[npages + i].bv_page = pages[i];
1061                         bv[npages + i].bv_offset = start;
1062                         bv[npages + i].bv_len = len - start;
1063                         rc -= len;
1064                         start = 0;
1065                 }
1066
1067                 npages += cur_npages;
1068         }
1069
1070         kvfree(pages);
1071         ctx->bv = bv;
1072         ctx->len = saved_len - count;
1073         ctx->npages = npages;
1074         iov_iter_bvec(&ctx->iter, rw, ctx->bv, npages, ctx->len);
1075         return 0;
1076 }
1077
1078 /**
1079  * cifs_alloc_hash - allocate hash and hash context together
1080  * @name: The name of the crypto hash algo
1081  * @shash: Where to put the pointer to the hash algo
1082  * @sdesc: Where to put the pointer to the hash descriptor
1083  *
1084  * The caller has to make sure @sdesc is initialized to either NULL or
1085  * a valid context. Both can be freed via cifs_free_hash().
1086  */
1087 int
1088 cifs_alloc_hash(const char *name,
1089                 struct crypto_shash **shash, struct sdesc **sdesc)
1090 {
1091         int rc = 0;
1092         size_t size;
1093
1094         if (*sdesc != NULL)
1095                 return 0;
1096
1097         *shash = crypto_alloc_shash(name, 0, 0);
1098         if (IS_ERR(*shash)) {
1099                 cifs_dbg(VFS, "Could not allocate crypto %s\n", name);
1100                 rc = PTR_ERR(*shash);
1101                 *shash = NULL;
1102                 *sdesc = NULL;
1103                 return rc;
1104         }
1105
1106         size = sizeof(struct shash_desc) + crypto_shash_descsize(*shash);
1107         *sdesc = kmalloc(size, GFP_KERNEL);
1108         if (*sdesc == NULL) {
1109                 cifs_dbg(VFS, "no memory left to allocate crypto %s\n", name);
1110                 crypto_free_shash(*shash);
1111                 *shash = NULL;
1112                 return -ENOMEM;
1113         }
1114
1115         (*sdesc)->shash.tfm = *shash;
1116         return 0;
1117 }
1118
1119 /**
1120  * cifs_free_hash - free hash and hash context together
1121  * @shash: Where to find the pointer to the hash algo
1122  * @sdesc: Where to find the pointer to the hash descriptor
1123  *
1124  * Freeing a NULL hash or context is safe.
1125  */
1126 void
1127 cifs_free_hash(struct crypto_shash **shash, struct sdesc **sdesc)
1128 {
1129         kfree(*sdesc);
1130         *sdesc = NULL;
1131         if (*shash)
1132                 crypto_free_shash(*shash);
1133         *shash = NULL;
1134 }
1135
1136 /**
1137  * rqst_page_get_length - obtain the length and offset for a page in smb_rqst
1138  * @rqst: The request descriptor
1139  * @page: The index of the page to query
1140  * @len: Where to store the length for this page:
1141  * @offset: Where to store the offset for this page
1142  */
1143 void rqst_page_get_length(const struct smb_rqst *rqst, unsigned int page,
1144                           unsigned int *len, unsigned int *offset)
1145 {
1146         *len = rqst->rq_pagesz;
1147         *offset = (page == 0) ? rqst->rq_offset : 0;
1148
1149         if (rqst->rq_npages == 1 || page == rqst->rq_npages-1)
1150                 *len = rqst->rq_tailsz;
1151         else if (page == 0)
1152                 *len = rqst->rq_pagesz - rqst->rq_offset;
1153 }
1154
1155 void extract_unc_hostname(const char *unc, const char **h, size_t *len)
1156 {
1157         const char *end;
1158
1159         /* skip initial slashes */
1160         while (*unc && (*unc == '\\' || *unc == '/'))
1161                 unc++;
1162
1163         end = unc;
1164
1165         while (*end && !(*end == '\\' || *end == '/'))
1166                 end++;
1167
1168         *h = unc;
1169         *len = end - unc;
1170 }
1171
1172 /**
1173  * copy_path_name - copy src path to dst, possibly truncating
1174  * @dst: The destination buffer
1175  * @src: The source name
1176  *
1177  * returns number of bytes written (including trailing nul)
1178  */
1179 int copy_path_name(char *dst, const char *src)
1180 {
1181         int name_len;
1182
1183         /*
1184          * PATH_MAX includes nul, so if strlen(src) >= PATH_MAX it
1185          * will truncate and strlen(dst) will be PATH_MAX-1
1186          */
1187         name_len = strscpy(dst, src, PATH_MAX);
1188         if (WARN_ON_ONCE(name_len < 0))
1189                 name_len = PATH_MAX-1;
1190
1191         /* we count the trailing nul */
1192         name_len++;
1193         return name_len;
1194 }
1195
1196 struct super_cb_data {
1197         void *data;
1198         struct super_block *sb;
1199 };
1200
1201 static void tcp_super_cb(struct super_block *sb, void *arg)
1202 {
1203         struct super_cb_data *sd = arg;
1204         struct TCP_Server_Info *server = sd->data;
1205         struct cifs_sb_info *cifs_sb;
1206         struct cifs_tcon *tcon;
1207
1208         if (sd->sb)
1209                 return;
1210
1211         cifs_sb = CIFS_SB(sb);
1212         tcon = cifs_sb_master_tcon(cifs_sb);
1213         if (tcon->ses->server == server)
1214                 sd->sb = sb;
1215 }
1216
1217 static struct super_block *__cifs_get_super(void (*f)(struct super_block *, void *),
1218                                             void *data)
1219 {
1220         struct super_cb_data sd = {
1221                 .data = data,
1222                 .sb = NULL,
1223         };
1224         struct file_system_type **fs_type = (struct file_system_type *[]) {
1225                 &cifs_fs_type, &smb3_fs_type, NULL,
1226         };
1227
1228         for (; *fs_type; fs_type++) {
1229                 iterate_supers_type(*fs_type, f, &sd);
1230                 if (sd.sb) {
1231                         /*
1232                          * Grab an active reference in order to prevent automounts (DFS links)
1233                          * of expiring and then freeing up our cifs superblock pointer while
1234                          * we're doing failover.
1235                          */
1236                         cifs_sb_active(sd.sb);
1237                         return sd.sb;
1238                 }
1239         }
1240         return ERR_PTR(-EINVAL);
1241 }
1242
1243 static void __cifs_put_super(struct super_block *sb)
1244 {
1245         if (!IS_ERR_OR_NULL(sb))
1246                 cifs_sb_deactive(sb);
1247 }
1248
1249 struct super_block *cifs_get_tcp_super(struct TCP_Server_Info *server)
1250 {
1251         return __cifs_get_super(tcp_super_cb, server);
1252 }
1253
1254 void cifs_put_tcp_super(struct super_block *sb)
1255 {
1256         __cifs_put_super(sb);
1257 }
1258
1259 #ifdef CONFIG_CIFS_DFS_UPCALL
1260 int match_target_ip(struct TCP_Server_Info *server,
1261                     const char *share, size_t share_len,
1262                     bool *result)
1263 {
1264         int rc;
1265         char *target, *tip = NULL;
1266         struct sockaddr tipaddr;
1267
1268         *result = false;
1269
1270         target = kzalloc(share_len + 3, GFP_KERNEL);
1271         if (!target) {
1272                 rc = -ENOMEM;
1273                 goto out;
1274         }
1275
1276         scnprintf(target, share_len + 3, "\\\\%.*s", (int)share_len, share);
1277
1278         cifs_dbg(FYI, "%s: target name: %s\n", __func__, target + 2);
1279
1280         rc = dns_resolve_server_name_to_ip(target, &tip, NULL);
1281         if (rc < 0)
1282                 goto out;
1283
1284         cifs_dbg(FYI, "%s: target ip: %s\n", __func__, tip);
1285
1286         if (!cifs_convert_address(&tipaddr, tip, strlen(tip))) {
1287                 cifs_dbg(VFS, "%s: failed to convert target ip address\n",
1288                          __func__);
1289                 rc = -EINVAL;
1290                 goto out;
1291         }
1292
1293         *result = cifs_match_ipaddr((struct sockaddr *)&server->dstaddr,
1294                                     &tipaddr);
1295         cifs_dbg(FYI, "%s: ip addresses match: %u\n", __func__, *result);
1296         rc = 0;
1297
1298 out:
1299         kfree(target);
1300         kfree(tip);
1301
1302         return rc;
1303 }
1304
1305 int cifs_update_super_prepath(struct cifs_sb_info *cifs_sb, char *prefix)
1306 {
1307         kfree(cifs_sb->prepath);
1308
1309         if (prefix && *prefix) {
1310                 cifs_sb->prepath = cifs_sanitize_prepath(prefix, GFP_ATOMIC);
1311                 if (!cifs_sb->prepath)
1312                         return -ENOMEM;
1313
1314                 convert_delimiter(cifs_sb->prepath, CIFS_DIR_SEP(cifs_sb));
1315         } else
1316                 cifs_sb->prepath = NULL;
1317
1318         cifs_sb->mnt_cifs_flags |= CIFS_MOUNT_USE_PREFIX_PATH;
1319         return 0;
1320 }
1321 #endif