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                 spin_lock_init(&ret_buf->ses_lock);
  73                 ret_buf->ses_status = SES_NEW;
  74                 ++ret_buf->ses_count;
  75                 INIT_LIST_HEAD(&ret_buf->smb_ses_list);
  76                 INIT_LIST_HEAD(&ret_buf->tcon_list);
  77                 mutex_init(&ret_buf->session_mutex);
  78                 spin_lock_init(&ret_buf->iface_lock);
  79                 INIT_LIST_HEAD(&ret_buf->iface_list);
  80                 spin_lock_init(&ret_buf->chan_lock);
  81         }
  82         return ret_buf;
  83 }
  84
  85 void
  86 sesInfoFree(struct cifs_ses *buf_to_free)
  87 {
  88         struct cifs_server_iface *iface = NULL, *niface = NULL;
  89
  90         if (buf_to_free == NULL) {
  91                 cifs_dbg(FYI, "Null buffer passed to sesInfoFree\n");
  92                 return;
  93         }
  94
  95         atomic_dec(&sesInfoAllocCount);
  96         kfree(buf_to_free->serverOS);
  97         kfree(buf_to_free->serverDomain);
  98         kfree(buf_to_free->serverNOS);
  99         kfree_sensitive(buf_to_free->password);
 100         kfree(buf_to_free->user_name);
 101         kfree(buf_to_free->domainName);
 102         kfree_sensitive(buf_to_free->auth_key.response);
 103         spin_lock(&buf_to_free->iface_lock);
 104         list_for_each_entry_safe(iface, niface, &buf_to_free->iface_list,
 105                                  iface_head)
 106                 kref_put(&iface->refcount, release_iface);
 107         spin_unlock(&buf_to_free->iface_lock);
 108         kfree_sensitive(buf_to_free);
 109 }
 110
 111 struct cifs_tcon *
 112 tconInfoAlloc(void)
 113 {
 114         struct cifs_tcon *ret_buf;
 115
 116         ret_buf = kzalloc(sizeof(*ret_buf), GFP_KERNEL);
 117         if (!ret_buf)
 118                 return NULL;
 119         ret_buf->crfid.fid = kzalloc(sizeof(*ret_buf->crfid.fid), GFP_KERNEL);
 120         if (!ret_buf->crfid.fid) {
 121                 kfree(ret_buf);
 122                 return NULL;
 123         }
 124         INIT_LIST_HEAD(&ret_buf->crfid.dirents.entries);
 125         mutex_init(&ret_buf->crfid.dirents.de_mutex);
 126
 127         atomic_inc(&tconInfoAllocCount);
 128         ret_buf->status = TID_NEW;
 129         ++ret_buf->tc_count;
 130         spin_lock_init(&ret_buf->tc_lock);
 131         INIT_LIST_HEAD(&ret_buf->openFileList);
 132         INIT_LIST_HEAD(&ret_buf->tcon_list);
 133         spin_lock_init(&ret_buf->open_file_lock);
 134         mutex_init(&ret_buf->crfid.fid_mutex);
 135         spin_lock_init(&ret_buf->stat_lock);
 136         atomic_set(&ret_buf->num_local_opens, 0);
 137         atomic_set(&ret_buf->num_remote_opens, 0);
 138
 139         return ret_buf;
 140 }
 141
 142 void
 143 tconInfoFree(struct cifs_tcon *buf_to_free)
 144 {
 145         if (buf_to_free == NULL) {
 146                 cifs_dbg(FYI, "Null buffer passed to tconInfoFree\n");
 147                 return;
 148         }
 149         atomic_dec(&tconInfoAllocCount);
 150         kfree(buf_to_free->nativeFileSystem);
 151         kfree_sensitive(buf_to_free->password);
 152         kfree(buf_to_free->crfid.fid);
 153         kfree(buf_to_free);
 154 }
 155
 156 struct smb_hdr *
 157 cifs_buf_get(void)
 158 {
 159         struct smb_hdr *ret_buf = NULL;
 160         /*
 161          * SMB2 header is bigger than CIFS one - no problems to clean some
 162          * more bytes for CIFS.
 163          */
 164         size_t buf_size = sizeof(struct smb2_hdr);
 165
 166         /*
 167          * We could use negotiated size instead of max_msgsize -
 168          * but it may be more efficient to always alloc same size
 169          * albeit slightly larger than necessary and maxbuffersize
 170          * defaults to this and can not be bigger.
 171          */
 172         ret_buf = mempool_alloc(cifs_req_poolp, GFP_NOFS);
 173
 174         /* clear the first few header bytes */
 175         /* for most paths, more is cleared in header_assemble */
 176         memset(ret_buf, 0, buf_size + 3);
 177         atomic_inc(&buf_alloc_count);
 178 #ifdef CONFIG_CIFS_STATS2
 179         atomic_inc(&total_buf_alloc_count);
 180 #endif /* CONFIG_CIFS_STATS2 */
 181
 182         return ret_buf;
 183 }
 184
 185 void
 186 cifs_buf_release(void *buf_to_free)
 187 {
 188         if (buf_to_free == NULL) {
 189                 /* cifs_dbg(FYI, "Null buffer passed to cifs_buf_release\n");*/
 190                 return;
 191         }
 192         mempool_free(buf_to_free, cifs_req_poolp);
 193
 194         atomic_dec(&buf_alloc_count);
 195         return;
 196 }
 197
 198 struct smb_hdr *
 199 cifs_small_buf_get(void)
 200 {
 201         struct smb_hdr *ret_buf = NULL;
 202
 203 /* We could use negotiated size instead of max_msgsize -
 204    but it may be more efficient to always alloc same size
 205    albeit slightly larger than necessary and maxbuffersize
 206    defaults to this and can not be bigger */
 207         ret_buf = mempool_alloc(cifs_sm_req_poolp, GFP_NOFS);
 208         /* No need to clear memory here, cleared in header assemble */
 209         /*      memset(ret_buf, 0, sizeof(struct smb_hdr) + 27);*/
 210         atomic_inc(&small_buf_alloc_count);
 211 #ifdef CONFIG_CIFS_STATS2
 212         atomic_inc(&total_small_buf_alloc_count);
 213 #endif /* CONFIG_CIFS_STATS2 */
 214
 215         return ret_buf;
 216 }
 217
 218 void
 219 cifs_small_buf_release(void *buf_to_free)
 220 {
 221
 222         if (buf_to_free == NULL) {
 223                 cifs_dbg(FYI, "Null buffer passed to cifs_small_buf_release\n");
 224                 return;
 225         }
 226         mempool_free(buf_to_free, cifs_sm_req_poolp);
 227
 228         atomic_dec(&small_buf_alloc_count);
 229         return;
 230 }
 231
 232 void
 233 free_rsp_buf(int resp_buftype, void *rsp)
 234 {
 235         if (resp_buftype == CIFS_SMALL_BUFFER)
 236                 cifs_small_buf_release(rsp);
 237         else if (resp_buftype == CIFS_LARGE_BUFFER)
 238                 cifs_buf_release(rsp);
 239 }
 240
 241 /* NB: MID can not be set if treeCon not passed in, in that
 242    case it is responsbility of caller to set the mid */
 243 void
 244 header_assemble(struct smb_hdr *buffer, char smb_command /* command */ ,
 245                 const struct cifs_tcon *treeCon, int word_count
 246                 /* length of fixed section (word count) in two byte units  */)
 247 {
 248         char *temp = (char *) buffer;
 249
 250         memset(temp, 0, 256); /* bigger than MAX_CIFS_HDR_SIZE */
 251
 252         buffer->smb_buf_length = cpu_to_be32(
 253             (2 * word_count) + sizeof(struct smb_hdr) -
 254             4 /*  RFC 1001 length field does not count */  +
 255             2 /* for bcc field itself */) ;
 256
 257         buffer->Protocol[0] = 0xFF;
 258         buffer->Protocol[1] = 'S';
 259         buffer->Protocol[2] = 'M';
 260         buffer->Protocol[3] = 'B';
 261         buffer->Command = smb_command;
 262         buffer->Flags = 0x00;   /* case sensitive */
 263         buffer->Flags2 = SMBFLG2_KNOWS_LONG_NAMES;
 264         buffer->Pid = cpu_to_le16((__u16)current->tgid);
 265         buffer->PidHigh = cpu_to_le16((__u16)(current->tgid >> 16));
 266         if (treeCon) {
 267                 buffer->Tid = treeCon->tid;
 268                 if (treeCon->ses) {
 269                         if (treeCon->ses->capabilities & CAP_UNICODE)
 270                                 buffer->Flags2 |= SMBFLG2_UNICODE;
 271                         if (treeCon->ses->capabilities & CAP_STATUS32)
 272                                 buffer->Flags2 |= SMBFLG2_ERR_STATUS;
 273
 274                         /* Uid is not converted */
 275                         buffer->Uid = treeCon->ses->Suid;
 276                         if (treeCon->ses->server)
 277                                 buffer->Mid = get_next_mid(treeCon->ses->server);
 278                 }
 279                 if (treeCon->Flags & SMB_SHARE_IS_IN_DFS)
 280                         buffer->Flags2 |= SMBFLG2_DFS;
 281                 if (treeCon->nocase)
 282                         buffer->Flags  |= SMBFLG_CASELESS;
 283                 if ((treeCon->ses) && (treeCon->ses->server))
 284                         if (treeCon->ses->server->sign)
 285                                 buffer->Flags2 |= SMBFLG2_SECURITY_SIGNATURE;
 286         }
 287
 288 /*  endian conversion of flags is now done just before sending */
 289         buffer->WordCount = (char) word_count;
 290         return;
 291 }
 292
 293 static int
 294 check_smb_hdr(struct smb_hdr *smb)
 295 {
 296         /* does it have the right SMB "signature" ? */
 297         if (*(__le32 *) smb->Protocol != cpu_to_le32(0x424d53ff)) {
 298                 cifs_dbg(VFS, "Bad protocol string signature header 0x%x\n",
 299                          *(unsigned int *)smb->Protocol);
 300                 return 1;
 301         }
 302
 303         /* if it's a response then accept */
 304         if (smb->Flags & SMBFLG_RESPONSE)
 305                 return 0;
 306
 307         /* only one valid case where server sends us request */
 308         if (smb->Command == SMB_COM_LOCKING_ANDX)
 309                 return 0;
 310
 311         cifs_dbg(VFS, "Server sent request, not response. mid=%u\n",
 312                  get_mid(smb));
 313         return 1;
 314 }
 315
 316 int
 317 checkSMB(char *buf, unsigned int total_read, struct TCP_Server_Info *server)
 318 {
 319         struct smb_hdr *smb = (struct smb_hdr *)buf;
 320         __u32 rfclen = be32_to_cpu(smb->smb_buf_length);
 321         __u32 clc_len;  /* calculated length */
 322         cifs_dbg(FYI, "checkSMB Length: 0x%x, smb_buf_length: 0x%x\n",
 323                  total_read, rfclen);
 324
 325         /* is this frame too small to even get to a BCC? */
 326         if (total_read < 2 + sizeof(struct smb_hdr)) {
 327                 if ((total_read >= sizeof(struct smb_hdr) - 1)
 328                             && (smb->Status.CifsError != 0)) {
 329                         /* it's an error return */
 330                         smb->WordCount = 0;
 331                         /* some error cases do not return wct and bcc */
 332                         return 0;
 333                 } else if ((total_read == sizeof(struct smb_hdr) + 1) &&
 334                                 (smb->WordCount == 0)) {
 335                         char *tmp = (char *)smb;
 336                         /* Need to work around a bug in two servers here */
 337                         /* First, check if the part of bcc they sent was zero */
 338                         if (tmp[sizeof(struct smb_hdr)] == 0) {
 339                                 /* some servers return only half of bcc
 340                                  * on simple responses (wct, bcc both zero)
 341                                  * in particular have seen this on
 342                                  * ulogoffX and FindClose. This leaves
 343                                  * one byte of bcc potentially unitialized
 344                                  */
 345                                 /* zero rest of bcc */
 346                                 tmp[sizeof(struct smb_hdr)+1] = 0;
 347                                 return 0;
 348                         }
 349                         cifs_dbg(VFS, "rcvd invalid byte count (bcc)\n");
 350                 } else {
 351                         cifs_dbg(VFS, "Length less than smb header size\n");
 352                 }
 353                 return -EIO;
 354         }
 355
 356         /* otherwise, there is enough to get to the BCC */
 357         if (check_smb_hdr(smb))
 358                 return -EIO;
 359         clc_len = smbCalcSize(smb, server);
 360
 361         if (4 + rfclen != total_read) {
 362                 cifs_dbg(VFS, "Length read does not match RFC1001 length %d\n",
 363                          rfclen);
 364                 return -EIO;
 365         }
 366
 367         if (4 + rfclen != clc_len) {
 368                 __u16 mid = get_mid(smb);
 369                 /* check if bcc wrapped around for large read responses */
 370                 if ((rfclen > 64 * 1024) && (rfclen > clc_len)) {
 371                         /* check if lengths match mod 64K */
 372                         if (((4 + rfclen) & 0xFFFF) == (clc_len & 0xFFFF))
 373                                 return 0; /* bcc wrapped */
 374                 }
 375                 cifs_dbg(FYI, "Calculated size %u vs length %u mismatch for mid=%u\n",
 376                          clc_len, 4 + rfclen, mid);
 377
 378                 if (4 + rfclen < clc_len) {
 379                         cifs_dbg(VFS, "RFC1001 size %u smaller than SMB for mid=%u\n",
 380                                  rfclen, mid);
 381                         return -EIO;
 382                 } else if (rfclen > clc_len + 512) {
 383                         /*
 384                          * Some servers (Windows XP in particular) send more
 385                          * data than the lengths in the SMB packet would
 386                          * indicate on certain calls (byte range locks and
 387                          * trans2 find first calls in particular). While the
 388                          * client can handle such a frame by ignoring the
 389                          * trailing data, we choose limit the amount of extra
 390                          * data to 512 bytes.
 391                          */
 392                         cifs_dbg(VFS, "RFC1001 size %u more than 512 bytes larger than SMB for mid=%u\n",
 393                                  rfclen, mid);
 394                         return -EIO;
 395                 }
 396         }
 397         return 0;
 398 }
 399
 400 bool
 401 is_valid_oplock_break(char *buffer, struct TCP_Server_Info *srv)
 402 {
 403         struct smb_hdr *buf = (struct smb_hdr *)buffer;
 404         struct smb_com_lock_req *pSMB = (struct smb_com_lock_req *)buf;
 405         struct cifs_ses *ses;
 406         struct cifs_tcon *tcon;
 407         struct cifsInodeInfo *pCifsInode;
 408         struct cifsFileInfo *netfile;
 409
 410         cifs_dbg(FYI, "Checking for oplock break or dnotify response\n");
 411         if ((pSMB->hdr.Command == SMB_COM_NT_TRANSACT) &&
 412            (pSMB->hdr.Flags & SMBFLG_RESPONSE)) {
 413                 struct smb_com_transaction_change_notify_rsp *pSMBr =
 414                         (struct smb_com_transaction_change_notify_rsp *)buf;
 415                 struct file_notify_information *pnotify;
 416                 __u32 data_offset = 0;
 417                 size_t len = srv->total_read - sizeof(pSMBr->hdr.smb_buf_length);
 418
 419                 if (get_bcc(buf) > sizeof(struct file_notify_information)) {
 420                         data_offset = le32_to_cpu(pSMBr->DataOffset);
 421
 422                         if (data_offset >
 423                             len - sizeof(struct file_notify_information)) {
 424                                 cifs_dbg(FYI, "Invalid data_offset %u\n",
 425                                          data_offset);
 426                                 return true;
 427                         }
 428                         pnotify = (struct file_notify_information *)
 429                                 ((char *)&pSMBr->hdr.Protocol + data_offset);
 430                         cifs_dbg(FYI, "dnotify on %s Action: 0x%x\n",
 431                                  pnotify->FileName, pnotify->Action);
 432                         /*   cifs_dump_mem("Rcvd notify Data: ",buf,
 433                                 sizeof(struct smb_hdr)+60); */
 434                         return true;
 435                 }
 436                 if (pSMBr->hdr.Status.CifsError) {
 437                         cifs_dbg(FYI, "notify err 0x%x\n",
 438                                  pSMBr->hdr.Status.CifsError);
 439                         return true;
 440                 }
 441                 return false;
 442         }
 443         if (pSMB->hdr.Command != SMB_COM_LOCKING_ANDX)
 444                 return false;
 445         if (pSMB->hdr.Flags & SMBFLG_RESPONSE) {
 446                 /* no sense logging error on invalid handle on oplock
 447                    break - harmless race between close request and oplock
 448                    break response is expected from time to time writing out
 449                    large dirty files cached on the client */
 450                 if ((NT_STATUS_INVALID_HANDLE) ==
 451                    le32_to_cpu(pSMB->hdr.Status.CifsError)) {
 452                         cifs_dbg(FYI, "Invalid handle on oplock break\n");
 453                         return true;
 454                 } else if (ERRbadfid ==
 455                    le16_to_cpu(pSMB->hdr.Status.DosError.Error)) {
 456                         return true;
 457                 } else {
 458                         return false; /* on valid oplock brk we get "request" */
 459                 }
 460         }
 461         if (pSMB->hdr.WordCount != 8)
 462                 return false;
 463
 464         cifs_dbg(FYI, "oplock type 0x%x level 0x%x\n",
 465                  pSMB->LockType, pSMB->OplockLevel);
 466         if (!(pSMB->LockType & LOCKING_ANDX_OPLOCK_RELEASE))
 467                 return false;
 468
 469         /* look up tcon based on tid & uid */
 470         spin_lock(&cifs_tcp_ses_lock);
 471         list_for_each_entry(ses, &srv->smb_ses_list, smb_ses_list) {
 472                 list_for_each_entry(tcon, &ses->tcon_list, tcon_list) {
 473                         if (tcon->tid != buf->Tid)
 474                                 continue;
 475
 476                         cifs_stats_inc(&tcon->stats.cifs_stats.num_oplock_brks);
 477                         spin_lock(&tcon->open_file_lock);
 478                         list_for_each_entry(netfile, &tcon->openFileList, tlist) {
 479                                 if (pSMB->Fid != netfile->fid.netfid)
 480                                         continue;
 481
 482                                 cifs_dbg(FYI, "file id match, oplock break\n");
 483                                 pCifsInode = CIFS_I(d_inode(netfile->dentry));
 484
 485                                 set_bit(CIFS_INODE_PENDING_OPLOCK_BREAK,
 486                                         &pCifsInode->flags);
 487
 488                                 netfile->oplock_epoch = 0;
 489                                 netfile->oplock_level = pSMB->OplockLevel;
 490                                 netfile->oplock_break_cancelled = false;
 491                                 cifs_queue_oplock_break(netfile);
 492
 493                                 spin_unlock(&tcon->open_file_lock);
 494                                 spin_unlock(&cifs_tcp_ses_lock);
 495                                 return true;
 496                         }
 497                         spin_unlock(&tcon->open_file_lock);
 498                         spin_unlock(&cifs_tcp_ses_lock);
 499                         cifs_dbg(FYI, "No matching file for oplock break\n");
 500                         return true;
 501                 }
 502         }
 503         spin_unlock(&cifs_tcp_ses_lock);
 504         cifs_dbg(FYI, "Can not process oplock break for non-existent connection\n");
 505         return true;
 506 }
 507
 508 void
 509 dump_smb(void *buf, int smb_buf_length)
 510 {
 511         if (traceSMB == 0)
 512                 return;
 513
 514         print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_NONE, 8, 2, buf,
 515                        smb_buf_length, true);
 516 }
 517
 518 void
 519 cifs_autodisable_serverino(struct cifs_sb_info *cifs_sb)
 520 {
 521         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SERVER_INUM) {
 522                 struct cifs_tcon *tcon = NULL;
 523
 524                 if (cifs_sb->master_tlink)
 525                         tcon = cifs_sb_master_tcon(cifs_sb);
 526
 527                 cifs_sb->mnt_cifs_flags &= ~CIFS_MOUNT_SERVER_INUM;
 528                 cifs_sb->mnt_cifs_serverino_autodisabled = true;
 529                 cifs_dbg(VFS, "Autodisabling the use of server inode numbers on %s\n",
 530                          tcon ? tcon->treeName : "new server");
 531                 cifs_dbg(VFS, "The server doesn't seem to support them properly or the files might be on different servers (DFS)\n");
 532                 cifs_dbg(VFS, "Hardlinks will not be recognized on this mount. Consider mounting with the \"noserverino\" option to silence this message.\n");
 533
 534         }
 535 }
 536
 537 void cifs_set_oplock_level(struct cifsInodeInfo *cinode, __u32 oplock)
 538 {
 539         oplock &= 0xF;
 540
 541         if (oplock == OPLOCK_EXCLUSIVE) {
 542                 cinode->oplock = CIFS_CACHE_WRITE_FLG | CIFS_CACHE_READ_FLG;
 543                 cifs_dbg(FYI, "Exclusive Oplock granted on inode %p\n",
 544                          &cinode->netfs.inode);
 545         } else if (oplock == OPLOCK_READ) {
 546                 cinode->oplock = CIFS_CACHE_READ_FLG;
 547                 cifs_dbg(FYI, "Level II Oplock granted on inode %p\n",
 548                          &cinode->netfs.inode);
 549         } else
 550                 cinode->oplock = 0;
 551 }
 552
 553 /*
 554  * We wait for oplock breaks to be processed before we attempt to perform
 555  * writes.
 556  */
 557 int cifs_get_writer(struct cifsInodeInfo *cinode)
 558 {
 559         int rc;
 560
 561 start:
 562         rc = wait_on_bit(&cinode->flags, CIFS_INODE_PENDING_OPLOCK_BREAK,
 563                          TASK_KILLABLE);
 564         if (rc)
 565                 return rc;
 566
 567         spin_lock(&cinode->writers_lock);
 568         if (!cinode->writers)
 569                 set_bit(CIFS_INODE_PENDING_WRITERS, &cinode->flags);
 570         cinode->writers++;
 571         /* Check to see if we have started servicing an oplock break */
 572         if (test_bit(CIFS_INODE_PENDING_OPLOCK_BREAK, &cinode->flags)) {
 573                 cinode->writers--;
 574                 if (cinode->writers == 0) {
 575                         clear_bit(CIFS_INODE_PENDING_WRITERS, &cinode->flags);
 576                         wake_up_bit(&cinode->flags, CIFS_INODE_PENDING_WRITERS);
 577                 }
 578                 spin_unlock(&cinode->writers_lock);
 579                 goto start;
 580         }
 581         spin_unlock(&cinode->writers_lock);
 582         return 0;
 583 }
 584
 585 void cifs_put_writer(struct cifsInodeInfo *cinode)
 586 {
 587         spin_lock(&cinode->writers_lock);
 588         cinode->writers--;
 589         if (cinode->writers == 0) {
 590                 clear_bit(CIFS_INODE_PENDING_WRITERS, &cinode->flags);
 591                 wake_up_bit(&cinode->flags, CIFS_INODE_PENDING_WRITERS);
 592         }
 593         spin_unlock(&cinode->writers_lock);
 594 }
 595
 596 /**
 597  * cifs_queue_oplock_break - queue the oplock break handler for cfile
 598  * @cfile: The file to break the oplock on
 599  *
 600  * This function is called from the demultiplex thread when it
 601  * receives an oplock break for @cfile.
 602  *
 603  * Assumes the tcon->open_file_lock is held.
 604  * Assumes cfile->file_info_lock is NOT held.
 605  */
 606 void cifs_queue_oplock_break(struct cifsFileInfo *cfile)
 607 {
 608         /*
 609          * Bump the handle refcount now while we hold the
 610          * open_file_lock to enforce the validity of it for the oplock
 611          * break handler. The matching put is done at the end of the
 612          * handler.
 613          */
 614         cifsFileInfo_get(cfile);
 615
 616         queue_work(cifsoplockd_wq, &cfile->oplock_break);
 617 }
 618
 619 void cifs_done_oplock_break(struct cifsInodeInfo *cinode)
 620 {
 621         clear_bit(CIFS_INODE_PENDING_OPLOCK_BREAK, &cinode->flags);
 622         wake_up_bit(&cinode->flags, CIFS_INODE_PENDING_OPLOCK_BREAK);
 623 }
 624
 625 bool
 626 backup_cred(struct cifs_sb_info *cifs_sb)
 627 {
 628         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_BACKUPUID) {
 629                 if (uid_eq(cifs_sb->ctx->backupuid, current_fsuid()))
 630                         return true;
 631         }
 632         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_BACKUPGID) {
 633                 if (in_group_p(cifs_sb->ctx->backupgid))
 634                         return true;
 635         }
 636
 637         return false;
 638 }
 639
 640 void
 641 cifs_del_pending_open(struct cifs_pending_open *open)
 642 {
 643         spin_lock(&tlink_tcon(open->tlink)->open_file_lock);
 644         list_del(&open->olist);
 645         spin_unlock(&tlink_tcon(open->tlink)->open_file_lock);
 646 }
 647
 648 void
 649 cifs_add_pending_open_locked(struct cifs_fid *fid, struct tcon_link *tlink,
 650                              struct cifs_pending_open *open)
 651 {
 652         memcpy(open->lease_key, fid->lease_key, SMB2_LEASE_KEY_SIZE);
 653         open->oplock = CIFS_OPLOCK_NO_CHANGE;
 654         open->tlink = tlink;
 655         fid->pending_open = open;
 656         list_add_tail(&open->olist, &tlink_tcon(tlink)->pending_opens);
 657 }
 658
 659 void
 660 cifs_add_pending_open(struct cifs_fid *fid, struct tcon_link *tlink,
 661                       struct cifs_pending_open *open)
 662 {
 663         spin_lock(&tlink_tcon(tlink)->open_file_lock);
 664         cifs_add_pending_open_locked(fid, tlink, open);
 665         spin_unlock(&tlink_tcon(open->tlink)->open_file_lock);
 666 }
 667
 668 /*
 669  * Critical section which runs after acquiring deferred_lock.
 670  * As there is no reference count on cifs_deferred_close, pdclose
 671  * should not be used outside deferred_lock.
 672  */
 673 bool
 674 cifs_is_deferred_close(struct cifsFileInfo *cfile, struct cifs_deferred_close **pdclose)
 675 {
 676         struct cifs_deferred_close *dclose;
 677
 678         list_for_each_entry(dclose, &CIFS_I(d_inode(cfile->dentry))->deferred_closes, dlist) {
 679                 if ((dclose->netfid == cfile->fid.netfid) &&
 680                         (dclose->persistent_fid == cfile->fid.persistent_fid) &&
 681                         (dclose->volatile_fid == cfile->fid.volatile_fid)) {
 682                         *pdclose = dclose;
 683                         return true;
 684                 }
 685         }
 686         return false;
 687 }
 688
 689 /*
 690  * Critical section which runs after acquiring deferred_lock.
 691  */
 692 void
 693 cifs_add_deferred_close(struct cifsFileInfo *cfile, struct cifs_deferred_close *dclose)
 694 {
 695         bool is_deferred = false;
 696         struct cifs_deferred_close *pdclose;
 697
 698         is_deferred = cifs_is_deferred_close(cfile, &pdclose);
 699         if (is_deferred) {
 700                 kfree(dclose);
 701                 return;
 702         }
 703
 704         dclose->tlink = cfile->tlink;
 705         dclose->netfid = cfile->fid.netfid;
 706         dclose->persistent_fid = cfile->fid.persistent_fid;
 707         dclose->volatile_fid = cfile->fid.volatile_fid;
 708         list_add_tail(&dclose->dlist, &CIFS_I(d_inode(cfile->dentry))->deferred_closes);
 709 }
 710
 711 /*
 712  * Critical section which runs after acquiring deferred_lock.
 713  */
 714 void
 715 cifs_del_deferred_close(struct cifsFileInfo *cfile)
 716 {
 717         bool is_deferred = false;
 718         struct cifs_deferred_close *dclose;
 719
 720         is_deferred = cifs_is_deferred_close(cfile, &dclose);
 721         if (!is_deferred)
 722                 return;
 723         list_del(&dclose->dlist);
 724         kfree(dclose);
 725 }
 726
 727 void
 728 cifs_close_deferred_file(struct cifsInodeInfo *cifs_inode)
 729 {
 730         struct cifsFileInfo *cfile = NULL;
 731         struct file_list *tmp_list, *tmp_next_list;
 732         struct list_head file_head;
 733
 734         if (cifs_inode == NULL)
 735                 return;
 736
 737         INIT_LIST_HEAD(&file_head);
 738         spin_lock(&cifs_inode->open_file_lock);
 739         list_for_each_entry(cfile, &cifs_inode->openFileList, flist) {
 740                 if (delayed_work_pending(&cfile->deferred)) {
 741                         if (cancel_delayed_work(&cfile->deferred)) {
 742                                 tmp_list = kmalloc(sizeof(struct file_list), GFP_ATOMIC);
 743                                 if (tmp_list == NULL)
 744                                         break;
 745                                 tmp_list->cfile = cfile;
 746                                 list_add_tail(&tmp_list->list, &file_head);
 747                         }
 748                 }
 749         }
 750         spin_unlock(&cifs_inode->open_file_lock);
 751
 752         list_for_each_entry_safe(tmp_list, tmp_next_list, &file_head, list) {
 753                 _cifsFileInfo_put(tmp_list->cfile, true, false);
 754                 list_del(&tmp_list->list);
 755                 kfree(tmp_list);
 756         }
 757 }
 758
 759 void
 760 cifs_close_all_deferred_files(struct cifs_tcon *tcon)
 761 {
 762         struct cifsFileInfo *cfile;
 763         struct file_list *tmp_list, *tmp_next_list;
 764         struct list_head file_head;
 765
 766         INIT_LIST_HEAD(&file_head);
 767         spin_lock(&tcon->open_file_lock);
 768         list_for_each_entry(cfile, &tcon->openFileList, tlist) {
 769                 if (delayed_work_pending(&cfile->deferred)) {
 770                         if (cancel_delayed_work(&cfile->deferred)) {
 771                                 tmp_list = kmalloc(sizeof(struct file_list), GFP_ATOMIC);
 772                                 if (tmp_list == NULL)
 773                                         break;
 774                                 tmp_list->cfile = cfile;
 775                                 list_add_tail(&tmp_list->list, &file_head);
 776                         }
 777                 }
 778         }
 779         spin_unlock(&tcon->open_file_lock);
 780
 781         list_for_each_entry_safe(tmp_list, tmp_next_list, &file_head, list) {
 782                 _cifsFileInfo_put(tmp_list->cfile, true, false);
 783                 list_del(&tmp_list->list);
 784                 kfree(tmp_list);
 785         }
 786 }
 787 void
 788 cifs_close_deferred_file_under_dentry(struct cifs_tcon *tcon, const char *path)
 789 {
 790         struct cifsFileInfo *cfile;
 791         struct file_list *tmp_list, *tmp_next_list;
 792         struct list_head file_head;
 793         void *page;
 794         const char *full_path;
 795
 796         INIT_LIST_HEAD(&file_head);
 797         page = alloc_dentry_path();
 798         spin_lock(&tcon->open_file_lock);
 799         list_for_each_entry(cfile, &tcon->openFileList, 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_pages2(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                 count -= rc;
1038                 rc += start;
1039                 cur_npages = DIV_ROUND_UP(rc, PAGE_SIZE);
1040
1041                 if (npages + cur_npages > max_pages) {
1042                         cifs_dbg(VFS, "out of vec array capacity (%u vs %u)\n",
1043                                  npages + cur_npages, max_pages);
1044                         break;
1045                 }
1046
1047                 for (i = 0; i < cur_npages; i++) {
1048                         len = rc > PAGE_SIZE ? PAGE_SIZE : rc;
1049                         bv[npages + i].bv_page = pages[i];
1050                         bv[npages + i].bv_offset = start;
1051                         bv[npages + i].bv_len = len - start;
1052                         rc -= len;
1053                         start = 0;
1054                 }
1055
1056                 npages += cur_npages;
1057         }
1058
1059         kvfree(pages);
1060         ctx->bv = bv;
1061         ctx->len = saved_len - count;
1062         ctx->npages = npages;
1063         iov_iter_bvec(&ctx->iter, rw, ctx->bv, npages, ctx->len);
1064         return 0;
1065 }
1066
1067 /**
1068  * cifs_alloc_hash - allocate hash and hash context together
1069  * @name: The name of the crypto hash algo
1070  * @shash: Where to put the pointer to the hash algo
1071  * @sdesc: Where to put the pointer to the hash descriptor
1072  *
1073  * The caller has to make sure @sdesc is initialized to either NULL or
1074  * a valid context. Both can be freed via cifs_free_hash().
1075  */
1076 int
1077 cifs_alloc_hash(const char *name,
1078                 struct crypto_shash **shash, struct sdesc **sdesc)
1079 {
1080         int rc = 0;
1081         size_t size;
1082
1083         if (*sdesc != NULL)
1084                 return 0;
1085
1086         *shash = crypto_alloc_shash(name, 0, 0);
1087         if (IS_ERR(*shash)) {
1088                 cifs_dbg(VFS, "Could not allocate crypto %s\n", name);
1089                 rc = PTR_ERR(*shash);
1090                 *shash = NULL;
1091                 *sdesc = NULL;
1092                 return rc;
1093         }
1094
1095         size = sizeof(struct shash_desc) + crypto_shash_descsize(*shash);
1096         *sdesc = kmalloc(size, GFP_KERNEL);
1097         if (*sdesc == NULL) {
1098                 cifs_dbg(VFS, "no memory left to allocate crypto %s\n", name);
1099                 crypto_free_shash(*shash);
1100                 *shash = NULL;
1101                 return -ENOMEM;
1102         }
1103
1104         (*sdesc)->shash.tfm = *shash;
1105         return 0;
1106 }
1107
1108 /**
1109  * cifs_free_hash - free hash and hash context together
1110  * @shash: Where to find the pointer to the hash algo
1111  * @sdesc: Where to find the pointer to the hash descriptor
1112  *
1113  * Freeing a NULL hash or context is safe.
1114  */
1115 void
1116 cifs_free_hash(struct crypto_shash **shash, struct sdesc **sdesc)
1117 {
1118         kfree(*sdesc);
1119         *sdesc = NULL;
1120         if (*shash)
1121                 crypto_free_shash(*shash);
1122         *shash = NULL;
1123 }
1124
1125 /**
1126  * rqst_page_get_length - obtain the length and offset for a page in smb_rqst
1127  * @rqst: The request descriptor
1128  * @page: The index of the page to query
1129  * @len: Where to store the length for this page:
1130  * @offset: Where to store the offset for this page
1131  */
1132 void rqst_page_get_length(struct smb_rqst *rqst, unsigned int page,
1133                                 unsigned int *len, unsigned int *offset)
1134 {
1135         *len = rqst->rq_pagesz;
1136         *offset = (page == 0) ? rqst->rq_offset : 0;
1137
1138         if (rqst->rq_npages == 1 || page == rqst->rq_npages-1)
1139                 *len = rqst->rq_tailsz;
1140         else if (page == 0)
1141                 *len = rqst->rq_pagesz - rqst->rq_offset;
1142 }
1143
1144 void extract_unc_hostname(const char *unc, const char **h, size_t *len)
1145 {
1146         const char *end;
1147
1148         /* skip initial slashes */
1149         while (*unc && (*unc == '\\' || *unc == '/'))
1150                 unc++;
1151
1152         end = unc;
1153
1154         while (*end && !(*end == '\\' || *end == '/'))
1155                 end++;
1156
1157         *h = unc;
1158         *len = end - unc;
1159 }
1160
1161 /**
1162  * copy_path_name - copy src path to dst, possibly truncating
1163  * @dst: The destination buffer
1164  * @src: The source name
1165  *
1166  * returns number of bytes written (including trailing nul)
1167  */
1168 int copy_path_name(char *dst, const char *src)
1169 {
1170         int name_len;
1171
1172         /*
1173          * PATH_MAX includes nul, so if strlen(src) >= PATH_MAX it
1174          * will truncate and strlen(dst) will be PATH_MAX-1
1175          */
1176         name_len = strscpy(dst, src, PATH_MAX);
1177         if (WARN_ON_ONCE(name_len < 0))
1178                 name_len = PATH_MAX-1;
1179
1180         /* we count the trailing nul */
1181         name_len++;
1182         return name_len;
1183 }
1184
1185 struct super_cb_data {
1186         void *data;
1187         struct super_block *sb;
1188 };
1189
1190 static void tcp_super_cb(struct super_block *sb, void *arg)
1191 {
1192         struct super_cb_data *sd = arg;
1193         struct TCP_Server_Info *server = sd->data;
1194         struct cifs_sb_info *cifs_sb;
1195         struct cifs_tcon *tcon;
1196
1197         if (sd->sb)
1198                 return;
1199
1200         cifs_sb = CIFS_SB(sb);
1201         tcon = cifs_sb_master_tcon(cifs_sb);
1202         if (tcon->ses->server == server)
1203                 sd->sb = sb;
1204 }
1205
1206 static struct super_block *__cifs_get_super(void (*f)(struct super_block *, void *),
1207                                             void *data)
1208 {
1209         struct super_cb_data sd = {
1210                 .data = data,
1211                 .sb = NULL,
1212         };
1213         struct file_system_type **fs_type = (struct file_system_type *[]) {
1214                 &cifs_fs_type, &smb3_fs_type, NULL,
1215         };
1216
1217         for (; *fs_type; fs_type++) {
1218                 iterate_supers_type(*fs_type, f, &sd);
1219                 if (sd.sb) {
1220                         /*
1221                          * Grab an active reference in order to prevent automounts (DFS links)
1222                          * of expiring and then freeing up our cifs superblock pointer while
1223                          * we're doing failover.
1224                          */
1225                         cifs_sb_active(sd.sb);
1226                         return sd.sb;
1227                 }
1228         }
1229         return ERR_PTR(-EINVAL);
1230 }
1231
1232 static void __cifs_put_super(struct super_block *sb)
1233 {
1234         if (!IS_ERR_OR_NULL(sb))
1235                 cifs_sb_deactive(sb);
1236 }
1237
1238 struct super_block *cifs_get_tcp_super(struct TCP_Server_Info *server)
1239 {
1240         return __cifs_get_super(tcp_super_cb, server);
1241 }
1242
1243 void cifs_put_tcp_super(struct super_block *sb)
1244 {
1245         __cifs_put_super(sb);
1246 }
1247
1248 #ifdef CONFIG_CIFS_DFS_UPCALL
1249 int match_target_ip(struct TCP_Server_Info *server,
1250                     const char *share, size_t share_len,
1251                     bool *result)
1252 {
1253         int rc;
1254         char *target, *tip = NULL;
1255         struct sockaddr tipaddr;
1256
1257         *result = false;
1258
1259         target = kzalloc(share_len + 3, GFP_KERNEL);
1260         if (!target) {
1261                 rc = -ENOMEM;
1262                 goto out;
1263         }
1264
1265         scnprintf(target, share_len + 3, "\\\\%.*s", (int)share_len, share);
1266
1267         cifs_dbg(FYI, "%s: target name: %s\n", __func__, target + 2);
1268
1269         rc = dns_resolve_server_name_to_ip(target, &tip, NULL);
1270         if (rc < 0)
1271                 goto out;
1272
1273         cifs_dbg(FYI, "%s: target ip: %s\n", __func__, tip);
1274
1275         if (!cifs_convert_address(&tipaddr, tip, strlen(tip))) {
1276                 cifs_dbg(VFS, "%s: failed to convert target ip address\n",
1277                          __func__);
1278                 rc = -EINVAL;
1279                 goto out;
1280         }
1281
1282         *result = cifs_match_ipaddr((struct sockaddr *)&server->dstaddr,
1283                                     &tipaddr);
1284         cifs_dbg(FYI, "%s: ip addresses match: %u\n", __func__, *result);
1285         rc = 0;
1286
1287 out:
1288         kfree(target);
1289         kfree(tip);
1290
1291         return rc;
1292 }
1293
1294 int cifs_update_super_prepath(struct cifs_sb_info *cifs_sb, char *prefix)
1295 {
1296         kfree(cifs_sb->prepath);
1297
1298         if (prefix && *prefix) {
1299                 cifs_sb->prepath = kstrdup(prefix, GFP_ATOMIC);
1300                 if (!cifs_sb->prepath)
1301                         return -ENOMEM;
1302
1303                 convert_delimiter(cifs_sb->prepath, CIFS_DIR_SEP(cifs_sb));
1304         } else
1305                 cifs_sb->prepath = NULL;
1306
1307         cifs_sb->mnt_cifs_flags |= CIFS_MOUNT_USE_PREFIX_PATH;
1308         return 0;
1309 }
1310
1311 /** cifs_dfs_query_info_nonascii_quirk
1312  * Handle weird Windows SMB server behaviour. It responds with
1313  * STATUS_OBJECT_NAME_INVALID code to SMB2 QUERY_INFO request
1314  * for "\<server>\<dfsname>\<linkpath>" DFS reference,
1315  * where <dfsname> contains non-ASCII unicode symbols.
1316  *
1317  * Check such DFS reference.
1318  */
1319 int cifs_dfs_query_info_nonascii_quirk(const unsigned int xid,
1320                                        struct cifs_tcon *tcon,
1321                                        struct cifs_sb_info *cifs_sb,
1322                                        const char *linkpath)
1323 {
1324         char *treename, *dfspath, sep;
1325         int treenamelen, linkpathlen, rc;
1326
1327         treename = tcon->treeName;
1328         /* MS-DFSC: All paths in REQ_GET_DFS_REFERRAL and RESP_GET_DFS_REFERRAL
1329          * messages MUST be encoded with exactly one leading backslash, not two
1330          * leading backslashes.
1331          */
1332         sep = CIFS_DIR_SEP(cifs_sb);
1333         if (treename[0] == sep && treename[1] == sep)
1334                 treename++;
1335         linkpathlen = strlen(linkpath);
1336         treenamelen = strnlen(treename, MAX_TREE_SIZE + 1);
1337         dfspath = kzalloc(treenamelen + linkpathlen + 1, GFP_KERNEL);
1338         if (!dfspath)
1339                 return -ENOMEM;
1340         if (treenamelen)
1341                 memcpy(dfspath, treename, treenamelen);
1342         memcpy(dfspath + treenamelen, linkpath, linkpathlen);
1343         rc = dfs_cache_find(xid, tcon->ses, cifs_sb->local_nls,
1344                             cifs_remap(cifs_sb), dfspath, NULL, NULL);
1345         if (rc == 0) {
1346                 cifs_dbg(FYI, "DFS ref '%s' is found, emulate -EREMOTE\n",
1347                          dfspath);
1348                 rc = -EREMOTE;
1349         } else {
1350                 cifs_dbg(FYI, "%s: dfs_cache_find returned %d\n", __func__, rc);
1351         }
1352         kfree(dfspath);
1353         return rc;
1354 }
1355 #endif