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Linux/fs/cifs/misc.c

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  1 /*
  2  *   fs/cifs/misc.c
  3  *
  4  *   Copyright (C) International Business Machines  Corp., 2002,2008
  5  *   Author(s): Steve French (sfrench@us.ibm.com)
  6  *
  7  *   This library is free software; you can redistribute it and/or modify
  8  *   it under the terms of the GNU Lesser General Public License as published
  9  *   by the Free Software Foundation; either version 2.1 of the License, or
 10  *   (at your option) any later version.
 11  *
 12  *   This library is distributed in the hope that it will be useful,
 13  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 14  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
 15  *   the GNU Lesser General Public License for more details.
 16  *
 17  *   You should have received a copy of the GNU Lesser General Public License
 18  *   along with this library; if not, write to the Free Software
 19  *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 20  */
 21 
 22 #include <linux/slab.h>
 23 #include <linux/ctype.h>
 24 #include <linux/mempool.h>
 25 #include <linux/vmalloc.h>
 26 #include "cifspdu.h"
 27 #include "cifsglob.h"
 28 #include "cifsproto.h"
 29 #include "cifs_debug.h"
 30 #include "smberr.h"
 31 #include "nterr.h"
 32 #include "cifs_unicode.h"
 33 #include "smb2pdu.h"
 34 
 35 extern mempool_t *cifs_sm_req_poolp;
 36 extern mempool_t *cifs_req_poolp;
 37 
 38 /* The xid serves as a useful identifier for each incoming vfs request,
 39    in a similar way to the mid which is useful to track each sent smb,
 40    and CurrentXid can also provide a running counter (although it
 41    will eventually wrap past zero) of the total vfs operations handled
 42    since the cifs fs was mounted */
 43 
 44 unsigned int
 45 _get_xid(void)
 46 {
 47         unsigned int xid;
 48 
 49         spin_lock(&GlobalMid_Lock);
 50         GlobalTotalActiveXid++;
 51 
 52         /* keep high water mark for number of simultaneous ops in filesystem */
 53         if (GlobalTotalActiveXid > GlobalMaxActiveXid)
 54                 GlobalMaxActiveXid = GlobalTotalActiveXid;
 55         if (GlobalTotalActiveXid > 65000)
 56                 cifs_dbg(FYI, "warning: more than 65000 requests active\n");
 57         xid = GlobalCurrentXid++;
 58         spin_unlock(&GlobalMid_Lock);
 59         return xid;
 60 }
 61 
 62 void
 63 _free_xid(unsigned int xid)
 64 {
 65         spin_lock(&GlobalMid_Lock);
 66         /* if (GlobalTotalActiveXid == 0)
 67                 BUG(); */
 68         GlobalTotalActiveXid--;
 69         spin_unlock(&GlobalMid_Lock);
 70 }
 71 
 72 struct cifs_ses *
 73 sesInfoAlloc(void)
 74 {
 75         struct cifs_ses *ret_buf;
 76 
 77         ret_buf = kzalloc(sizeof(struct cifs_ses), GFP_KERNEL);
 78         if (ret_buf) {
 79                 atomic_inc(&sesInfoAllocCount);
 80                 ret_buf->status = CifsNew;
 81                 ++ret_buf->ses_count;
 82                 INIT_LIST_HEAD(&ret_buf->smb_ses_list);
 83                 INIT_LIST_HEAD(&ret_buf->tcon_list);
 84                 mutex_init(&ret_buf->session_mutex);
 85                 spin_lock_init(&ret_buf->iface_lock);
 86         }
 87         return ret_buf;
 88 }
 89 
 90 void
 91 sesInfoFree(struct cifs_ses *buf_to_free)
 92 {
 93         if (buf_to_free == NULL) {
 94                 cifs_dbg(FYI, "Null buffer passed to sesInfoFree\n");
 95                 return;
 96         }
 97 
 98         atomic_dec(&sesInfoAllocCount);
 99         kfree(buf_to_free->serverOS);
100         kfree(buf_to_free->serverDomain);
101         kfree(buf_to_free->serverNOS);
102         kzfree(buf_to_free->password);
103         kfree(buf_to_free->user_name);
104         kfree(buf_to_free->domainName);
105         kzfree(buf_to_free->auth_key.response);
106         kfree(buf_to_free->iface_list);
107         kzfree(buf_to_free);
108 }
109 
110 struct cifs_tcon *
111 tconInfoAlloc(void)
112 {
113         struct cifs_tcon *ret_buf;
114 
115         ret_buf = kzalloc(sizeof(*ret_buf), GFP_KERNEL);
116         if (!ret_buf)
117                 return NULL;
118         ret_buf->crfid.fid = kzalloc(sizeof(*ret_buf->crfid.fid), GFP_KERNEL);
119         if (!ret_buf->crfid.fid) {
120                 kfree(ret_buf);
121                 return NULL;
122         }
123 
124         atomic_inc(&tconInfoAllocCount);
125         ret_buf->tidStatus = CifsNew;
126         ++ret_buf->tc_count;
127         INIT_LIST_HEAD(&ret_buf->openFileList);
128         INIT_LIST_HEAD(&ret_buf->tcon_list);
129         spin_lock_init(&ret_buf->open_file_lock);
130         mutex_init(&ret_buf->crfid.fid_mutex);
131         spin_lock_init(&ret_buf->stat_lock);
132         atomic_set(&ret_buf->num_local_opens, 0);
133         atomic_set(&ret_buf->num_remote_opens, 0);
134 
135         return ret_buf;
136 }
137 
138 void
139 tconInfoFree(struct cifs_tcon *buf_to_free)
140 {
141         if (buf_to_free == NULL) {
142                 cifs_dbg(FYI, "Null buffer passed to tconInfoFree\n");
143                 return;
144         }
145         atomic_dec(&tconInfoAllocCount);
146         kfree(buf_to_free->nativeFileSystem);
147         kzfree(buf_to_free->password);
148         kfree(buf_to_free->crfid.fid);
149 #ifdef CONFIG_CIFS_DFS_UPCALL
150         kfree(buf_to_free->dfs_path);
151 #endif
152         kfree(buf_to_free);
153 }
154 
155 struct smb_hdr *
156 cifs_buf_get(void)
157 {
158         struct smb_hdr *ret_buf = NULL;
159         /*
160          * SMB2 header is bigger than CIFS one - no problems to clean some
161          * more bytes for CIFS.
162          */
163         size_t buf_size = sizeof(struct smb2_sync_hdr);
164 
165         /*
166          * We could use negotiated size instead of max_msgsize -
167          * but it may be more efficient to always alloc same size
168          * albeit slightly larger than necessary and maxbuffersize
169          * defaults to this and can not be bigger.
170          */
171         ret_buf = mempool_alloc(cifs_req_poolp, GFP_NOFS);
172 
173         /* clear the first few header bytes */
174         /* for most paths, more is cleared in header_assemble */
175         memset(ret_buf, 0, buf_size + 3);
176         atomic_inc(&bufAllocCount);
177 #ifdef CONFIG_CIFS_STATS2
178         atomic_inc(&totBufAllocCount);
179 #endif /* CONFIG_CIFS_STATS2 */
180 
181         return ret_buf;
182 }
183 
184 void
185 cifs_buf_release(void *buf_to_free)
186 {
187         if (buf_to_free == NULL) {
188                 /* cifs_dbg(FYI, "Null buffer passed to cifs_buf_release\n");*/
189                 return;
190         }
191         mempool_free(buf_to_free, cifs_req_poolp);
192 
193         atomic_dec(&bufAllocCount);
194         return;
195 }
196 
197 struct smb_hdr *
198 cifs_small_buf_get(void)
199 {
200         struct smb_hdr *ret_buf = NULL;
201 
202 /* We could use negotiated size instead of max_msgsize -
203    but it may be more efficient to always alloc same size
204    albeit slightly larger than necessary and maxbuffersize
205    defaults to this and can not be bigger */
206         ret_buf = mempool_alloc(cifs_sm_req_poolp, GFP_NOFS);
207         /* No need to clear memory here, cleared in header assemble */
208         /*      memset(ret_buf, 0, sizeof(struct smb_hdr) + 27);*/
209         atomic_inc(&smBufAllocCount);
210 #ifdef CONFIG_CIFS_STATS2
211         atomic_inc(&totSmBufAllocCount);
212 #endif /* CONFIG_CIFS_STATS2 */
213 
214         return ret_buf;
215 }
216 
217 void
218 cifs_small_buf_release(void *buf_to_free)
219 {
220 
221         if (buf_to_free == NULL) {
222                 cifs_dbg(FYI, "Null buffer passed to cifs_small_buf_release\n");
223                 return;
224         }
225         mempool_free(buf_to_free, cifs_sm_req_poolp);
226 
227         atomic_dec(&smBufAllocCount);
228         return;
229 }
230 
231 void
232 free_rsp_buf(int resp_buftype, void *rsp)
233 {
234         if (resp_buftype == CIFS_SMALL_BUFFER)
235                 cifs_small_buf_release(rsp);
236         else if (resp_buftype == CIFS_LARGE_BUFFER)
237                 cifs_buf_release(rsp);
238 }
239 
240 /* NB: MID can not be set if treeCon not passed in, in that
241    case it is responsbility of caller to set the mid */
242 void
243 header_assemble(struct smb_hdr *buffer, char smb_command /* command */ ,
244                 const struct cifs_tcon *treeCon, int word_count
245                 /* length of fixed section (word count) in two byte units  */)
246 {
247         char *temp = (char *) buffer;
248 
249         memset(temp, 0, 256); /* bigger than MAX_CIFS_HDR_SIZE */
250 
251         buffer->smb_buf_length = cpu_to_be32(
252             (2 * word_count) + sizeof(struct smb_hdr) -
253             4 /*  RFC 1001 length field does not count */  +
254             2 /* for bcc field itself */) ;
255 
256         buffer->Protocol[0] = 0xFF;
257         buffer->Protocol[1] = 'S';
258         buffer->Protocol[2] = 'M';
259         buffer->Protocol[3] = 'B';
260         buffer->Command = smb_command;
261         buffer->Flags = 0x00;   /* case sensitive */
262         buffer->Flags2 = SMBFLG2_KNOWS_LONG_NAMES;
263         buffer->Pid = cpu_to_le16((__u16)current->tgid);
264         buffer->PidHigh = cpu_to_le16((__u16)(current->tgid >> 16));
265         if (treeCon) {
266                 buffer->Tid = treeCon->tid;
267                 if (treeCon->ses) {
268                         if (treeCon->ses->capabilities & CAP_UNICODE)
269                                 buffer->Flags2 |= SMBFLG2_UNICODE;
270                         if (treeCon->ses->capabilities & CAP_STATUS32)
271                                 buffer->Flags2 |= SMBFLG2_ERR_STATUS;
272 
273                         /* Uid is not converted */
274                         buffer->Uid = treeCon->ses->Suid;
275                         buffer->Mid = get_next_mid(treeCon->ses->server);
276                 }
277                 if (treeCon->Flags & SMB_SHARE_IS_IN_DFS)
278                         buffer->Flags2 |= SMBFLG2_DFS;
279                 if (treeCon->nocase)
280                         buffer->Flags  |= SMBFLG_CASELESS;
281                 if ((treeCon->ses) && (treeCon->ses->server))
282                         if (treeCon->ses->server->sign)
283                                 buffer->Flags2 |= SMBFLG2_SECURITY_SIGNATURE;
284         }
285 
286 /*  endian conversion of flags is now done just before sending */
287         buffer->WordCount = (char) word_count;
288         return;
289 }
290 
291 static int
292 check_smb_hdr(struct smb_hdr *smb)
293 {
294         /* does it have the right SMB "signature" ? */
295         if (*(__le32 *) smb->Protocol != cpu_to_le32(0x424d53ff)) {
296                 cifs_dbg(VFS, "Bad protocol string signature header 0x%x\n",
297                          *(unsigned int *)smb->Protocol);
298                 return 1;
299         }
300 
301         /* if it's a response then accept */
302         if (smb->Flags & SMBFLG_RESPONSE)
303                 return 0;
304 
305         /* only one valid case where server sends us request */
306         if (smb->Command == SMB_COM_LOCKING_ANDX)
307                 return 0;
308 
309         cifs_dbg(VFS, "Server sent request, not response. mid=%u\n",
310                  get_mid(smb));
311         return 1;
312 }
313 
314 int
315 checkSMB(char *buf, unsigned int total_read, struct TCP_Server_Info *server)
316 {
317         struct smb_hdr *smb = (struct smb_hdr *)buf;
318         __u32 rfclen = be32_to_cpu(smb->smb_buf_length);
319         __u32 clc_len;  /* calculated length */
320         cifs_dbg(FYI, "checkSMB Length: 0x%x, smb_buf_length: 0x%x\n",
321                  total_read, rfclen);
322 
323         /* is this frame too small to even get to a BCC? */
324         if (total_read < 2 + sizeof(struct smb_hdr)) {
325                 if ((total_read >= sizeof(struct smb_hdr) - 1)
326                             && (smb->Status.CifsError != 0)) {
327                         /* it's an error return */
328                         smb->WordCount = 0;
329                         /* some error cases do not return wct and bcc */
330                         return 0;
331                 } else if ((total_read == sizeof(struct smb_hdr) + 1) &&
332                                 (smb->WordCount == 0)) {
333                         char *tmp = (char *)smb;
334                         /* Need to work around a bug in two servers here */
335                         /* First, check if the part of bcc they sent was zero */
336                         if (tmp[sizeof(struct smb_hdr)] == 0) {
337                                 /* some servers return only half of bcc
338                                  * on simple responses (wct, bcc both zero)
339                                  * in particular have seen this on
340                                  * ulogoffX and FindClose. This leaves
341                                  * one byte of bcc potentially unitialized
342                                  */
343                                 /* zero rest of bcc */
344                                 tmp[sizeof(struct smb_hdr)+1] = 0;
345                                 return 0;
346                         }
347                         cifs_dbg(VFS, "rcvd invalid byte count (bcc)\n");
348                 } else {
349                         cifs_dbg(VFS, "Length less than smb header size\n");
350                 }
351                 return -EIO;
352         }
353 
354         /* otherwise, there is enough to get to the BCC */
355         if (check_smb_hdr(smb))
356                 return -EIO;
357         clc_len = smbCalcSize(smb, server);
358 
359         if (4 + rfclen != total_read) {
360                 cifs_dbg(VFS, "Length read does not match RFC1001 length %d\n",
361                          rfclen);
362                 return -EIO;
363         }
364 
365         if (4 + rfclen != clc_len) {
366                 __u16 mid = get_mid(smb);
367                 /* check if bcc wrapped around for large read responses */
368                 if ((rfclen > 64 * 1024) && (rfclen > clc_len)) {
369                         /* check if lengths match mod 64K */
370                         if (((4 + rfclen) & 0xFFFF) == (clc_len & 0xFFFF))
371                                 return 0; /* bcc wrapped */
372                 }
373                 cifs_dbg(FYI, "Calculated size %u vs length %u mismatch for mid=%u\n",
374                          clc_len, 4 + rfclen, mid);
375 
376                 if (4 + rfclen < clc_len) {
377                         cifs_dbg(VFS, "RFC1001 size %u smaller than SMB for mid=%u\n",
378                                  rfclen, mid);
379                         return -EIO;
380                 } else if (rfclen > clc_len + 512) {
381                         /*
382                          * Some servers (Windows XP in particular) send more
383                          * data than the lengths in the SMB packet would
384                          * indicate on certain calls (byte range locks and
385                          * trans2 find first calls in particular). While the
386                          * client can handle such a frame by ignoring the
387                          * trailing data, we choose limit the amount of extra
388                          * data to 512 bytes.
389                          */
390                         cifs_dbg(VFS, "RFC1001 size %u more than 512 bytes larger than SMB for mid=%u\n",
391                                  rfclen, mid);
392                         return -EIO;
393                 }
394         }
395         return 0;
396 }
397 
398 bool
399 is_valid_oplock_break(char *buffer, struct TCP_Server_Info *srv)
400 {
401         struct smb_hdr *buf = (struct smb_hdr *)buffer;
402         struct smb_com_lock_req *pSMB = (struct smb_com_lock_req *)buf;
403         struct list_head *tmp, *tmp1, *tmp2;
404         struct cifs_ses *ses;
405         struct cifs_tcon *tcon;
406         struct cifsInodeInfo *pCifsInode;
407         struct cifsFileInfo *netfile;
408 
409         cifs_dbg(FYI, "Checking for oplock break or dnotify response\n");
410         if ((pSMB->hdr.Command == SMB_COM_NT_TRANSACT) &&
411            (pSMB->hdr.Flags & SMBFLG_RESPONSE)) {
412                 struct smb_com_transaction_change_notify_rsp *pSMBr =
413                         (struct smb_com_transaction_change_notify_rsp *)buf;
414                 struct file_notify_information *pnotify;
415                 __u32 data_offset = 0;
416                 size_t len = srv->total_read - sizeof(pSMBr->hdr.smb_buf_length);
417 
418                 if (get_bcc(buf) > sizeof(struct file_notify_information)) {
419                         data_offset = le32_to_cpu(pSMBr->DataOffset);
420 
421                         if (data_offset >
422                             len - sizeof(struct file_notify_information)) {
423                                 cifs_dbg(FYI, "invalid data_offset %u\n",
424                                          data_offset);
425                                 return true;
426                         }
427                         pnotify = (struct file_notify_information *)
428                                 ((char *)&pSMBr->hdr.Protocol + data_offset);
429                         cifs_dbg(FYI, "dnotify on %s Action: 0x%x\n",
430                                  pnotify->FileName, pnotify->Action);
431                         /*   cifs_dump_mem("Rcvd notify Data: ",buf,
432                                 sizeof(struct smb_hdr)+60); */
433                         return true;
434                 }
435                 if (pSMBr->hdr.Status.CifsError) {
436                         cifs_dbg(FYI, "notify err 0x%x\n",
437                                  pSMBr->hdr.Status.CifsError);
438                         return true;
439                 }
440                 return false;
441         }
442         if (pSMB->hdr.Command != SMB_COM_LOCKING_ANDX)
443                 return false;
444         if (pSMB->hdr.Flags & SMBFLG_RESPONSE) {
445                 /* no sense logging error on invalid handle on oplock
446                    break - harmless race between close request and oplock
447                    break response is expected from time to time writing out
448                    large dirty files cached on the client */
449                 if ((NT_STATUS_INVALID_HANDLE) ==
450                    le32_to_cpu(pSMB->hdr.Status.CifsError)) {
451                         cifs_dbg(FYI, "invalid handle on oplock break\n");
452                         return true;
453                 } else if (ERRbadfid ==
454                    le16_to_cpu(pSMB->hdr.Status.DosError.Error)) {
455                         return true;
456                 } else {
457                         return false; /* on valid oplock brk we get "request" */
458                 }
459         }
460         if (pSMB->hdr.WordCount != 8)
461                 return false;
462 
463         cifs_dbg(FYI, "oplock type 0x%x level 0x%x\n",
464                  pSMB->LockType, pSMB->OplockLevel);
465         if (!(pSMB->LockType & LOCKING_ANDX_OPLOCK_RELEASE))
466                 return false;
467 
468         /* look up tcon based on tid & uid */
469         spin_lock(&cifs_tcp_ses_lock);
470         list_for_each(tmp, &srv->smb_ses_list) {
471                 ses = list_entry(tmp, struct cifs_ses, smb_ses_list);
472                 list_for_each(tmp1, &ses->tcon_list) {
473                         tcon = list_entry(tmp1, struct cifs_tcon, tcon_list);
474                         if (tcon->tid != buf->Tid)
475                                 continue;
476 
477                         cifs_stats_inc(&tcon->stats.cifs_stats.num_oplock_brks);
478                         spin_lock(&tcon->open_file_lock);
479                         list_for_each(tmp2, &tcon->openFileList) {
480                                 netfile = list_entry(tmp2, struct cifsFileInfo,
481                                                      tlist);
482                                 if (pSMB->Fid != netfile->fid.netfid)
483                                         continue;
484 
485                                 cifs_dbg(FYI, "file id match, oplock break\n");
486                                 pCifsInode = CIFS_I(d_inode(netfile->dentry));
487 
488                                 set_bit(CIFS_INODE_PENDING_OPLOCK_BREAK,
489                                         &pCifsInode->flags);
490 
491                                 /*
492                                  * Set flag if the server downgrades the oplock
493                                  * to L2 else clear.
494                                  */
495                                 if (pSMB->OplockLevel)
496                                         set_bit(
497                                            CIFS_INODE_DOWNGRADE_OPLOCK_TO_L2,
498                                            &pCifsInode->flags);
499                                 else
500                                         clear_bit(
501                                            CIFS_INODE_DOWNGRADE_OPLOCK_TO_L2,
502                                            &pCifsInode->flags);
503 
504                                 cifs_queue_oplock_break(netfile);
505                                 netfile->oplock_break_cancelled = false;
506 
507                                 spin_unlock(&tcon->open_file_lock);
508                                 spin_unlock(&cifs_tcp_ses_lock);
509                                 return true;
510                         }
511                         spin_unlock(&tcon->open_file_lock);
512                         spin_unlock(&cifs_tcp_ses_lock);
513                         cifs_dbg(FYI, "No matching file for oplock break\n");
514                         return true;
515                 }
516         }
517         spin_unlock(&cifs_tcp_ses_lock);
518         cifs_dbg(FYI, "Can not process oplock break for non-existent connection\n");
519         return true;
520 }
521 
522 void
523 dump_smb(void *buf, int smb_buf_length)
524 {
525         if (traceSMB == 0)
526                 return;
527 
528         print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_NONE, 8, 2, buf,
529                        smb_buf_length, true);
530 }
531 
532 void
533 cifs_autodisable_serverino(struct cifs_sb_info *cifs_sb)
534 {
535         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SERVER_INUM) {
536                 struct cifs_tcon *tcon = NULL;
537 
538                 if (cifs_sb->master_tlink)
539                         tcon = cifs_sb_master_tcon(cifs_sb);
540 
541                 cifs_sb->mnt_cifs_flags &= ~CIFS_MOUNT_SERVER_INUM;
542                 cifs_sb->mnt_cifs_serverino_autodisabled = true;
543                 cifs_dbg(VFS, "Autodisabling the use of server inode numbers on %s.\n",
544                          tcon ? tcon->treeName : "new server");
545                 cifs_dbg(VFS, "The server doesn't seem to support them properly or the files might be on different servers (DFS).\n");
546                 cifs_dbg(VFS, "Hardlinks will not be recognized on this mount. Consider mounting with the \"noserverino\" option to silence this message.\n");
547 
548         }
549 }
550 
551 void cifs_set_oplock_level(struct cifsInodeInfo *cinode, __u32 oplock)
552 {
553         oplock &= 0xF;
554 
555         if (oplock == OPLOCK_EXCLUSIVE) {
556                 cinode->oplock = CIFS_CACHE_WRITE_FLG | CIFS_CACHE_READ_FLG;
557                 cifs_dbg(FYI, "Exclusive Oplock granted on inode %p\n",
558                          &cinode->vfs_inode);
559         } else if (oplock == OPLOCK_READ) {
560                 cinode->oplock = CIFS_CACHE_READ_FLG;
561                 cifs_dbg(FYI, "Level II Oplock granted on inode %p\n",
562                          &cinode->vfs_inode);
563         } else
564                 cinode->oplock = 0;
565 }
566 
567 /*
568  * We wait for oplock breaks to be processed before we attempt to perform
569  * writes.
570  */
571 int cifs_get_writer(struct cifsInodeInfo *cinode)
572 {
573         int rc;
574 
575 start:
576         rc = wait_on_bit(&cinode->flags, CIFS_INODE_PENDING_OPLOCK_BREAK,
577                          TASK_KILLABLE);
578         if (rc)
579                 return rc;
580 
581         spin_lock(&cinode->writers_lock);
582         if (!cinode->writers)
583                 set_bit(CIFS_INODE_PENDING_WRITERS, &cinode->flags);
584         cinode->writers++;
585         /* Check to see if we have started servicing an oplock break */
586         if (test_bit(CIFS_INODE_PENDING_OPLOCK_BREAK, &cinode->flags)) {
587                 cinode->writers--;
588                 if (cinode->writers == 0) {
589                         clear_bit(CIFS_INODE_PENDING_WRITERS, &cinode->flags);
590                         wake_up_bit(&cinode->flags, CIFS_INODE_PENDING_WRITERS);
591                 }
592                 spin_unlock(&cinode->writers_lock);
593                 goto start;
594         }
595         spin_unlock(&cinode->writers_lock);
596         return 0;
597 }
598 
599 void cifs_put_writer(struct cifsInodeInfo *cinode)
600 {
601         spin_lock(&cinode->writers_lock);
602         cinode->writers--;
603         if (cinode->writers == 0) {
604                 clear_bit(CIFS_INODE_PENDING_WRITERS, &cinode->flags);
605                 wake_up_bit(&cinode->flags, CIFS_INODE_PENDING_WRITERS);
606         }
607         spin_unlock(&cinode->writers_lock);
608 }
609 
610 /**
611  * cifs_queue_oplock_break - queue the oplock break handler for cfile
612  *
613  * This function is called from the demultiplex thread when it
614  * receives an oplock break for @cfile.
615  *
616  * Assumes the tcon->open_file_lock is held.
617  * Assumes cfile->file_info_lock is NOT held.
618  */
619 void cifs_queue_oplock_break(struct cifsFileInfo *cfile)
620 {
621         /*
622          * Bump the handle refcount now while we hold the
623          * open_file_lock to enforce the validity of it for the oplock
624          * break handler. The matching put is done at the end of the
625          * handler.
626          */
627         cifsFileInfo_get(cfile);
628 
629         queue_work(cifsoplockd_wq, &cfile->oplock_break);
630 }
631 
632 void cifs_done_oplock_break(struct cifsInodeInfo *cinode)
633 {
634         clear_bit(CIFS_INODE_PENDING_OPLOCK_BREAK, &cinode->flags);
635         wake_up_bit(&cinode->flags, CIFS_INODE_PENDING_OPLOCK_BREAK);
636 }
637 
638 bool
639 backup_cred(struct cifs_sb_info *cifs_sb)
640 {
641         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_BACKUPUID) {
642                 if (uid_eq(cifs_sb->mnt_backupuid, current_fsuid()))
643                         return true;
644         }
645         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_BACKUPGID) {
646                 if (in_group_p(cifs_sb->mnt_backupgid))
647                         return true;
648         }
649 
650         return false;
651 }
652 
653 void
654 cifs_del_pending_open(struct cifs_pending_open *open)
655 {
656         spin_lock(&tlink_tcon(open->tlink)->open_file_lock);
657         list_del(&open->olist);
658         spin_unlock(&tlink_tcon(open->tlink)->open_file_lock);
659 }
660 
661 void
662 cifs_add_pending_open_locked(struct cifs_fid *fid, struct tcon_link *tlink,
663                              struct cifs_pending_open *open)
664 {
665         memcpy(open->lease_key, fid->lease_key, SMB2_LEASE_KEY_SIZE);
666         open->oplock = CIFS_OPLOCK_NO_CHANGE;
667         open->tlink = tlink;
668         fid->pending_open = open;
669         list_add_tail(&open->olist, &tlink_tcon(tlink)->pending_opens);
670 }
671 
672 void
673 cifs_add_pending_open(struct cifs_fid *fid, struct tcon_link *tlink,
674                       struct cifs_pending_open *open)
675 {
676         spin_lock(&tlink_tcon(tlink)->open_file_lock);
677         cifs_add_pending_open_locked(fid, tlink, open);
678         spin_unlock(&tlink_tcon(open->tlink)->open_file_lock);
679 }
680 
681 /* parses DFS refferal V3 structure
682  * caller is responsible for freeing target_nodes
683  * returns:
684  * - on success - 0
685  * - on failure - errno
686  */
687 int
688 parse_dfs_referrals(struct get_dfs_referral_rsp *rsp, u32 rsp_size,
689                     unsigned int *num_of_nodes,
690                     struct dfs_info3_param **target_nodes,
691                     const struct nls_table *nls_codepage, int remap,
692                     const char *searchName, bool is_unicode)
693 {
694         int i, rc = 0;
695         char *data_end;
696         struct dfs_referral_level_3 *ref;
697 
698         *num_of_nodes = le16_to_cpu(rsp->NumberOfReferrals);
699 
700         if (*num_of_nodes < 1) {
701                 cifs_dbg(VFS, "num_referrals: must be at least > 0, but we get num_referrals = %d\n",
702                          *num_of_nodes);
703                 rc = -EINVAL;
704                 goto parse_DFS_referrals_exit;
705         }
706 
707         ref = (struct dfs_referral_level_3 *) &(rsp->referrals);
708         if (ref->VersionNumber != cpu_to_le16(3)) {
709                 cifs_dbg(VFS, "Referrals of V%d version are not supported, should be V3\n",
710                          le16_to_cpu(ref->VersionNumber));
711                 rc = -EINVAL;
712                 goto parse_DFS_referrals_exit;
713         }
714 
715         /* get the upper boundary of the resp buffer */
716         data_end = (char *)rsp + rsp_size;
717 
718         cifs_dbg(FYI, "num_referrals: %d dfs flags: 0x%x ...\n",
719                  *num_of_nodes, le32_to_cpu(rsp->DFSFlags));
720 
721         *target_nodes = kcalloc(*num_of_nodes, sizeof(struct dfs_info3_param),
722                                 GFP_KERNEL);
723         if (*target_nodes == NULL) {
724                 rc = -ENOMEM;
725                 goto parse_DFS_referrals_exit;
726         }
727 
728         /* collect necessary data from referrals */
729         for (i = 0; i < *num_of_nodes; i++) {
730                 char *temp;
731                 int max_len;
732                 struct dfs_info3_param *node = (*target_nodes)+i;
733 
734                 node->flags = le32_to_cpu(rsp->DFSFlags);
735                 if (is_unicode) {
736                         __le16 *tmp = kmalloc(strlen(searchName)*2 + 2,
737                                                 GFP_KERNEL);
738                         if (tmp == NULL) {
739                                 rc = -ENOMEM;
740                                 goto parse_DFS_referrals_exit;
741                         }
742                         cifsConvertToUTF16((__le16 *) tmp, searchName,
743                                            PATH_MAX, nls_codepage, remap);
744                         node->path_consumed = cifs_utf16_bytes(tmp,
745                                         le16_to_cpu(rsp->PathConsumed),
746                                         nls_codepage);
747                         kfree(tmp);
748                 } else
749                         node->path_consumed = le16_to_cpu(rsp->PathConsumed);
750 
751                 node->server_type = le16_to_cpu(ref->ServerType);
752                 node->ref_flag = le16_to_cpu(ref->ReferralEntryFlags);
753 
754                 /* copy DfsPath */
755                 temp = (char *)ref + le16_to_cpu(ref->DfsPathOffset);
756                 max_len = data_end - temp;
757                 node->path_name = cifs_strndup_from_utf16(temp, max_len,
758                                                 is_unicode, nls_codepage);
759                 if (!node->path_name) {
760                         rc = -ENOMEM;
761                         goto parse_DFS_referrals_exit;
762                 }
763 
764                 /* copy link target UNC */
765                 temp = (char *)ref + le16_to_cpu(ref->NetworkAddressOffset);
766                 max_len = data_end - temp;
767                 node->node_name = cifs_strndup_from_utf16(temp, max_len,
768                                                 is_unicode, nls_codepage);
769                 if (!node->node_name) {
770                         rc = -ENOMEM;
771                         goto parse_DFS_referrals_exit;
772                 }
773 
774                 node->ttl = le32_to_cpu(ref->TimeToLive);
775 
776                 ref++;
777         }
778 
779 parse_DFS_referrals_exit:
780         if (rc) {
781                 free_dfs_info_array(*target_nodes, *num_of_nodes);
782                 *target_nodes = NULL;
783                 *num_of_nodes = 0;
784         }
785         return rc;
786 }
787 
788 struct cifs_aio_ctx *
789 cifs_aio_ctx_alloc(void)
790 {
791         struct cifs_aio_ctx *ctx;
792 
793         /*
794          * Must use kzalloc to initialize ctx->bv to NULL and ctx->direct_io
795          * to false so that we know when we have to unreference pages within
796          * cifs_aio_ctx_release()
797          */
798         ctx = kzalloc(sizeof(struct cifs_aio_ctx), GFP_KERNEL);
799         if (!ctx)
800                 return NULL;
801 
802         INIT_LIST_HEAD(&ctx->list);
803         mutex_init(&ctx->aio_mutex);
804         init_completion(&ctx->done);
805         kref_init(&ctx->refcount);
806         return ctx;
807 }
808 
809 void
810 cifs_aio_ctx_release(struct kref *refcount)
811 {
812         struct cifs_aio_ctx *ctx = container_of(refcount,
813                                         struct cifs_aio_ctx, refcount);
814 
815         cifsFileInfo_put(ctx->cfile);
816 
817         /*
818          * ctx->bv is only set if setup_aio_ctx_iter() was call successfuly
819          * which means that iov_iter_get_pages() was a success and thus that
820          * we have taken reference on pages.
821          */
822         if (ctx->bv) {
823                 unsigned i;
824 
825                 for (i = 0; i < ctx->npages; i++) {
826                         if (ctx->should_dirty)
827                                 set_page_dirty(ctx->bv[i].bv_page);
828                         put_page(ctx->bv[i].bv_page);
829                 }
830                 kvfree(ctx->bv);
831         }
832 
833         kfree(ctx);
834 }
835 
836 #define CIFS_AIO_KMALLOC_LIMIT (1024 * 1024)
837 
838 int
839 setup_aio_ctx_iter(struct cifs_aio_ctx *ctx, struct iov_iter *iter, int rw)
840 {
841         ssize_t rc;
842         unsigned int cur_npages;
843         unsigned int npages = 0;
844         unsigned int i;
845         size_t len;
846         size_t count = iov_iter_count(iter);
847         unsigned int saved_len;
848         size_t start;
849         unsigned int max_pages = iov_iter_npages(iter, INT_MAX);
850         struct page **pages = NULL;
851         struct bio_vec *bv = NULL;
852 
853         if (iov_iter_is_kvec(iter)) {
854                 memcpy(&ctx->iter, iter, sizeof(struct iov_iter));
855                 ctx->len = count;
856                 iov_iter_advance(iter, count);
857                 return 0;
858         }
859 
860         if (max_pages * sizeof(struct bio_vec) <= CIFS_AIO_KMALLOC_LIMIT)
861                 bv = kmalloc_array(max_pages, sizeof(struct bio_vec),
862                                    GFP_KERNEL);
863 
864         if (!bv) {
865                 bv = vmalloc(array_size(max_pages, sizeof(struct bio_vec)));
866                 if (!bv)
867                         return -ENOMEM;
868         }
869 
870         if (max_pages * sizeof(struct page *) <= CIFS_AIO_KMALLOC_LIMIT)
871                 pages = kmalloc_array(max_pages, sizeof(struct page *),
872                                       GFP_KERNEL);
873 
874         if (!pages) {
875                 pages = vmalloc(array_size(max_pages, sizeof(struct page *)));
876                 if (!pages) {
877                         kvfree(bv);
878                         return -ENOMEM;
879                 }
880         }
881 
882         saved_len = count;
883 
884         while (count && npages < max_pages) {
885                 rc = iov_iter_get_pages(iter, pages, count, max_pages, &start);
886                 if (rc < 0) {
887                         cifs_dbg(VFS, "couldn't get user pages (rc=%zd)\n", rc);
888                         break;
889                 }
890 
891                 if (rc > count) {
892                         cifs_dbg(VFS, "get pages rc=%zd more than %zu\n", rc,
893                                  count);
894                         break;
895                 }
896 
897                 iov_iter_advance(iter, rc);
898                 count -= rc;
899                 rc += start;
900                 cur_npages = DIV_ROUND_UP(rc, PAGE_SIZE);
901 
902                 if (npages + cur_npages > max_pages) {
903                         cifs_dbg(VFS, "out of vec array capacity (%u vs %u)\n",
904                                  npages + cur_npages, max_pages);
905                         break;
906                 }
907 
908                 for (i = 0; i < cur_npages; i++) {
909                         len = rc > PAGE_SIZE ? PAGE_SIZE : rc;
910                         bv[npages + i].bv_page = pages[i];
911                         bv[npages + i].bv_offset = start;
912                         bv[npages + i].bv_len = len - start;
913                         rc -= len;
914                         start = 0;
915                 }
916 
917                 npages += cur_npages;
918         }
919 
920         kvfree(pages);
921         ctx->bv = bv;
922         ctx->len = saved_len - count;
923         ctx->npages = npages;
924         iov_iter_bvec(&ctx->iter, rw, ctx->bv, npages, ctx->len);
925         return 0;
926 }
927 
928 /**
929  * cifs_alloc_hash - allocate hash and hash context together
930  *
931  * The caller has to make sure @sdesc is initialized to either NULL or
932  * a valid context. Both can be freed via cifs_free_hash().
933  */
934 int
935 cifs_alloc_hash(const char *name,
936                 struct crypto_shash **shash, struct sdesc **sdesc)
937 {
938         int rc = 0;
939         size_t size;
940 
941         if (*sdesc != NULL)
942                 return 0;
943 
944         *shash = crypto_alloc_shash(name, 0, 0);
945         if (IS_ERR(*shash)) {
946                 cifs_dbg(VFS, "could not allocate crypto %s\n", name);
947                 rc = PTR_ERR(*shash);
948                 *shash = NULL;
949                 *sdesc = NULL;
950                 return rc;
951         }
952 
953         size = sizeof(struct shash_desc) + crypto_shash_descsize(*shash);
954         *sdesc = kmalloc(size, GFP_KERNEL);
955         if (*sdesc == NULL) {
956                 cifs_dbg(VFS, "no memory left to allocate crypto %s\n", name);
957                 crypto_free_shash(*shash);
958                 *shash = NULL;
959                 return -ENOMEM;
960         }
961 
962         (*sdesc)->shash.tfm = *shash;
963         return 0;
964 }
965 
966 /**
967  * cifs_free_hash - free hash and hash context together
968  *
969  * Freeing a NULL hash or context is safe.
970  */
971 void
972 cifs_free_hash(struct crypto_shash **shash, struct sdesc **sdesc)
973 {
974         kfree(*sdesc);
975         *sdesc = NULL;
976         if (*shash)
977                 crypto_free_shash(*shash);
978         *shash = NULL;
979 }
980 
981 /**
982  * rqst_page_get_length - obtain the length and offset for a page in smb_rqst
983  * Input: rqst - a smb_rqst, page - a page index for rqst
984  * Output: *len - the length for this page, *offset - the offset for this page
985  */
986 void rqst_page_get_length(struct smb_rqst *rqst, unsigned int page,
987                                 unsigned int *len, unsigned int *offset)
988 {
989         *len = rqst->rq_pagesz;
990         *offset = (page == 0) ? rqst->rq_offset : 0;
991 
992         if (rqst->rq_npages == 1 || page == rqst->rq_npages-1)
993                 *len = rqst->rq_tailsz;
994         else if (page == 0)
995                 *len = rqst->rq_pagesz - rqst->rq_offset;
996 }
997 
998 void extract_unc_hostname(const char *unc, const char **h, size_t *len)
999 {
1000         const char *end;
1001 
1002         /* skip initial slashes */
1003         while (*unc && (*unc == '\\' || *unc == '/'))
1004                 unc++;
1005 
1006         end = unc;
1007 
1008         while (*end && !(*end == '\\' || *end == '/'))
1009                 end++;
1010 
1011         *h = unc;
1012         *len = end - unc;
1013 }
1014 
1015 /**
1016  * copy_path_name - copy src path to dst, possibly truncating
1017  *
1018  * returns number of bytes written (including trailing nul)
1019  */
1020 int copy_path_name(char *dst, const char *src)
1021 {
1022         int name_len;
1023 
1024         /*
1025          * PATH_MAX includes nul, so if strlen(src) >= PATH_MAX it
1026          * will truncate and strlen(dst) will be PATH_MAX-1
1027          */
1028         name_len = strscpy(dst, src, PATH_MAX);
1029         if (WARN_ON_ONCE(name_len < 0))
1030                 name_len = PATH_MAX-1;
1031 
1032         /* we count the trailing nul */
1033         name_len++;
1034         return name_len;
1035 }
1036 

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