Version:  2.0.40 2.2.26 2.4.37 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10

Linux/fs/open.c

  1 /*
  2  *  linux/fs/open.c
  3  *
  4  *  Copyright (C) 1991, 1992  Linus Torvalds
  5  */
  6 
  7 #include <linux/string.h>
  8 #include <linux/mm.h>
  9 #include <linux/file.h>
 10 #include <linux/fdtable.h>
 11 #include <linux/fsnotify.h>
 12 #include <linux/module.h>
 13 #include <linux/tty.h>
 14 #include <linux/namei.h>
 15 #include <linux/backing-dev.h>
 16 #include <linux/capability.h>
 17 #include <linux/securebits.h>
 18 #include <linux/security.h>
 19 #include <linux/mount.h>
 20 #include <linux/fcntl.h>
 21 #include <linux/slab.h>
 22 #include <linux/uaccess.h>
 23 #include <linux/fs.h>
 24 #include <linux/personality.h>
 25 #include <linux/pagemap.h>
 26 #include <linux/syscalls.h>
 27 #include <linux/rcupdate.h>
 28 #include <linux/audit.h>
 29 #include <linux/falloc.h>
 30 #include <linux/fs_struct.h>
 31 #include <linux/ima.h>
 32 #include <linux/dnotify.h>
 33 #include <linux/compat.h>
 34 
 35 #include "internal.h"
 36 
 37 int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs,
 38         struct file *filp)
 39 {
 40         int ret;
 41         struct iattr newattrs;
 42 
 43         /* Not pretty: "inode->i_size" shouldn't really be signed. But it is. */
 44         if (length < 0)
 45                 return -EINVAL;
 46 
 47         newattrs.ia_size = length;
 48         newattrs.ia_valid = ATTR_SIZE | time_attrs;
 49         if (filp) {
 50                 newattrs.ia_file = filp;
 51                 newattrs.ia_valid |= ATTR_FILE;
 52         }
 53 
 54         /* Remove suid, sgid, and file capabilities on truncate too */
 55         ret = dentry_needs_remove_privs(dentry);
 56         if (ret < 0)
 57                 return ret;
 58         if (ret)
 59                 newattrs.ia_valid |= ret | ATTR_FORCE;
 60 
 61         inode_lock(dentry->d_inode);
 62         /* Note any delegations or leases have already been broken: */
 63         ret = notify_change(dentry, &newattrs, NULL);
 64         inode_unlock(dentry->d_inode);
 65         return ret;
 66 }
 67 
 68 long vfs_truncate(const struct path *path, loff_t length)
 69 {
 70         struct inode *inode;
 71         struct dentry *upperdentry;
 72         long error;
 73 
 74         inode = path->dentry->d_inode;
 75 
 76         /* For directories it's -EISDIR, for other non-regulars - -EINVAL */
 77         if (S_ISDIR(inode->i_mode))
 78                 return -EISDIR;
 79         if (!S_ISREG(inode->i_mode))
 80                 return -EINVAL;
 81 
 82         error = mnt_want_write(path->mnt);
 83         if (error)
 84                 goto out;
 85 
 86         error = inode_permission(inode, MAY_WRITE);
 87         if (error)
 88                 goto mnt_drop_write_and_out;
 89 
 90         error = -EPERM;
 91         if (IS_APPEND(inode))
 92                 goto mnt_drop_write_and_out;
 93 
 94         /*
 95          * If this is an overlayfs then do as if opening the file so we get
 96          * write access on the upper inode, not on the overlay inode.  For
 97          * non-overlay filesystems d_real() is an identity function.
 98          */
 99         upperdentry = d_real(path->dentry, NULL, O_WRONLY);
100         error = PTR_ERR(upperdentry);
101         if (IS_ERR(upperdentry))
102                 goto mnt_drop_write_and_out;
103 
104         error = get_write_access(upperdentry->d_inode);
105         if (error)
106                 goto mnt_drop_write_and_out;
107 
108         /*
109          * Make sure that there are no leases.  get_write_access() protects
110          * against the truncate racing with a lease-granting setlease().
111          */
112         error = break_lease(inode, O_WRONLY);
113         if (error)
114                 goto put_write_and_out;
115 
116         error = locks_verify_truncate(inode, NULL, length);
117         if (!error)
118                 error = security_path_truncate(path);
119         if (!error)
120                 error = do_truncate(path->dentry, length, 0, NULL);
121 
122 put_write_and_out:
123         put_write_access(upperdentry->d_inode);
124 mnt_drop_write_and_out:
125         mnt_drop_write(path->mnt);
126 out:
127         return error;
128 }
129 EXPORT_SYMBOL_GPL(vfs_truncate);
130 
131 static long do_sys_truncate(const char __user *pathname, loff_t length)
132 {
133         unsigned int lookup_flags = LOOKUP_FOLLOW;
134         struct path path;
135         int error;
136 
137         if (length < 0) /* sorry, but loff_t says... */
138                 return -EINVAL;
139 
140 retry:
141         error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
142         if (!error) {
143                 error = vfs_truncate(&path, length);
144                 path_put(&path);
145         }
146         if (retry_estale(error, lookup_flags)) {
147                 lookup_flags |= LOOKUP_REVAL;
148                 goto retry;
149         }
150         return error;
151 }
152 
153 SYSCALL_DEFINE2(truncate, const char __user *, path, long, length)
154 {
155         return do_sys_truncate(path, length);
156 }
157 
158 #ifdef CONFIG_COMPAT
159 COMPAT_SYSCALL_DEFINE2(truncate, const char __user *, path, compat_off_t, length)
160 {
161         return do_sys_truncate(path, length);
162 }
163 #endif
164 
165 static long do_sys_ftruncate(unsigned int fd, loff_t length, int small)
166 {
167         struct inode *inode;
168         struct dentry *dentry;
169         struct fd f;
170         int error;
171 
172         error = -EINVAL;
173         if (length < 0)
174                 goto out;
175         error = -EBADF;
176         f = fdget(fd);
177         if (!f.file)
178                 goto out;
179 
180         /* explicitly opened as large or we are on 64-bit box */
181         if (f.file->f_flags & O_LARGEFILE)
182                 small = 0;
183 
184         dentry = f.file->f_path.dentry;
185         inode = dentry->d_inode;
186         error = -EINVAL;
187         if (!S_ISREG(inode->i_mode) || !(f.file->f_mode & FMODE_WRITE))
188                 goto out_putf;
189 
190         error = -EINVAL;
191         /* Cannot ftruncate over 2^31 bytes without large file support */
192         if (small && length > MAX_NON_LFS)
193                 goto out_putf;
194 
195         error = -EPERM;
196         if (IS_APPEND(inode))
197                 goto out_putf;
198 
199         sb_start_write(inode->i_sb);
200         error = locks_verify_truncate(inode, f.file, length);
201         if (!error)
202                 error = security_path_truncate(&f.file->f_path);
203         if (!error)
204                 error = do_truncate(dentry, length, ATTR_MTIME|ATTR_CTIME, f.file);
205         sb_end_write(inode->i_sb);
206 out_putf:
207         fdput(f);
208 out:
209         return error;
210 }
211 
212 SYSCALL_DEFINE2(ftruncate, unsigned int, fd, unsigned long, length)
213 {
214         return do_sys_ftruncate(fd, length, 1);
215 }
216 
217 #ifdef CONFIG_COMPAT
218 COMPAT_SYSCALL_DEFINE2(ftruncate, unsigned int, fd, compat_ulong_t, length)
219 {
220         return do_sys_ftruncate(fd, length, 1);
221 }
222 #endif
223 
224 /* LFS versions of truncate are only needed on 32 bit machines */
225 #if BITS_PER_LONG == 32
226 SYSCALL_DEFINE2(truncate64, const char __user *, path, loff_t, length)
227 {
228         return do_sys_truncate(path, length);
229 }
230 
231 SYSCALL_DEFINE2(ftruncate64, unsigned int, fd, loff_t, length)
232 {
233         return do_sys_ftruncate(fd, length, 0);
234 }
235 #endif /* BITS_PER_LONG == 32 */
236 
237 
238 int vfs_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
239 {
240         struct inode *inode = file_inode(file);
241         long ret;
242 
243         if (offset < 0 || len <= 0)
244                 return -EINVAL;
245 
246         /* Return error if mode is not supported */
247         if (mode & ~FALLOC_FL_SUPPORTED_MASK)
248                 return -EOPNOTSUPP;
249 
250         /* Punch hole and zero range are mutually exclusive */
251         if ((mode & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE)) ==
252             (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE))
253                 return -EOPNOTSUPP;
254 
255         /* Punch hole must have keep size set */
256         if ((mode & FALLOC_FL_PUNCH_HOLE) &&
257             !(mode & FALLOC_FL_KEEP_SIZE))
258                 return -EOPNOTSUPP;
259 
260         /* Collapse range should only be used exclusively. */
261         if ((mode & FALLOC_FL_COLLAPSE_RANGE) &&
262             (mode & ~FALLOC_FL_COLLAPSE_RANGE))
263                 return -EINVAL;
264 
265         /* Insert range should only be used exclusively. */
266         if ((mode & FALLOC_FL_INSERT_RANGE) &&
267             (mode & ~FALLOC_FL_INSERT_RANGE))
268                 return -EINVAL;
269 
270         /* Unshare range should only be used with allocate mode. */
271         if ((mode & FALLOC_FL_UNSHARE_RANGE) &&
272             (mode & ~(FALLOC_FL_UNSHARE_RANGE | FALLOC_FL_KEEP_SIZE)))
273                 return -EINVAL;
274 
275         if (!(file->f_mode & FMODE_WRITE))
276                 return -EBADF;
277 
278         /*
279          * We can only allow pure fallocate on append only files
280          */
281         if ((mode & ~FALLOC_FL_KEEP_SIZE) && IS_APPEND(inode))
282                 return -EPERM;
283 
284         if (IS_IMMUTABLE(inode))
285                 return -EPERM;
286 
287         /*
288          * We cannot allow any fallocate operation on an active swapfile
289          */
290         if (IS_SWAPFILE(inode))
291                 return -ETXTBSY;
292 
293         /*
294          * Revalidate the write permissions, in case security policy has
295          * changed since the files were opened.
296          */
297         ret = security_file_permission(file, MAY_WRITE);
298         if (ret)
299                 return ret;
300 
301         if (S_ISFIFO(inode->i_mode))
302                 return -ESPIPE;
303 
304         /*
305          * Let individual file system decide if it supports preallocation
306          * for directories or not.
307          */
308         if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode) &&
309             !S_ISBLK(inode->i_mode))
310                 return -ENODEV;
311 
312         /* Check for wrap through zero too */
313         if (((offset + len) > inode->i_sb->s_maxbytes) || ((offset + len) < 0))
314                 return -EFBIG;
315 
316         if (!file->f_op->fallocate)
317                 return -EOPNOTSUPP;
318 
319         sb_start_write(inode->i_sb);
320         ret = file->f_op->fallocate(file, mode, offset, len);
321 
322         /*
323          * Create inotify and fanotify events.
324          *
325          * To keep the logic simple always create events if fallocate succeeds.
326          * This implies that events are even created if the file size remains
327          * unchanged, e.g. when using flag FALLOC_FL_KEEP_SIZE.
328          */
329         if (ret == 0)
330                 fsnotify_modify(file);
331 
332         sb_end_write(inode->i_sb);
333         return ret;
334 }
335 EXPORT_SYMBOL_GPL(vfs_fallocate);
336 
337 SYSCALL_DEFINE4(fallocate, int, fd, int, mode, loff_t, offset, loff_t, len)
338 {
339         struct fd f = fdget(fd);
340         int error = -EBADF;
341 
342         if (f.file) {
343                 error = vfs_fallocate(f.file, mode, offset, len);
344                 fdput(f);
345         }
346         return error;
347 }
348 
349 /*
350  * access() needs to use the real uid/gid, not the effective uid/gid.
351  * We do this by temporarily clearing all FS-related capabilities and
352  * switching the fsuid/fsgid around to the real ones.
353  */
354 SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode)
355 {
356         const struct cred *old_cred;
357         struct cred *override_cred;
358         struct path path;
359         struct inode *inode;
360         int res;
361         unsigned int lookup_flags = LOOKUP_FOLLOW;
362 
363         if (mode & ~S_IRWXO)    /* where's F_OK, X_OK, W_OK, R_OK? */
364                 return -EINVAL;
365 
366         override_cred = prepare_creds();
367         if (!override_cred)
368                 return -ENOMEM;
369 
370         override_cred->fsuid = override_cred->uid;
371         override_cred->fsgid = override_cred->gid;
372 
373         if (!issecure(SECURE_NO_SETUID_FIXUP)) {
374                 /* Clear the capabilities if we switch to a non-root user */
375                 kuid_t root_uid = make_kuid(override_cred->user_ns, 0);
376                 if (!uid_eq(override_cred->uid, root_uid))
377                         cap_clear(override_cred->cap_effective);
378                 else
379                         override_cred->cap_effective =
380                                 override_cred->cap_permitted;
381         }
382 
383         old_cred = override_creds(override_cred);
384 retry:
385         res = user_path_at(dfd, filename, lookup_flags, &path);
386         if (res)
387                 goto out;
388 
389         inode = d_backing_inode(path.dentry);
390 
391         if ((mode & MAY_EXEC) && S_ISREG(inode->i_mode)) {
392                 /*
393                  * MAY_EXEC on regular files is denied if the fs is mounted
394                  * with the "noexec" flag.
395                  */
396                 res = -EACCES;
397                 if (path_noexec(&path))
398                         goto out_path_release;
399         }
400 
401         res = inode_permission(inode, mode | MAY_ACCESS);
402         /* SuS v2 requires we report a read only fs too */
403         if (res || !(mode & S_IWOTH) || special_file(inode->i_mode))
404                 goto out_path_release;
405         /*
406          * This is a rare case where using __mnt_is_readonly()
407          * is OK without a mnt_want/drop_write() pair.  Since
408          * no actual write to the fs is performed here, we do
409          * not need to telegraph to that to anyone.
410          *
411          * By doing this, we accept that this access is
412          * inherently racy and know that the fs may change
413          * state before we even see this result.
414          */
415         if (__mnt_is_readonly(path.mnt))
416                 res = -EROFS;
417 
418 out_path_release:
419         path_put(&path);
420         if (retry_estale(res, lookup_flags)) {
421                 lookup_flags |= LOOKUP_REVAL;
422                 goto retry;
423         }
424 out:
425         revert_creds(old_cred);
426         put_cred(override_cred);
427         return res;
428 }
429 
430 SYSCALL_DEFINE2(access, const char __user *, filename, int, mode)
431 {
432         return sys_faccessat(AT_FDCWD, filename, mode);
433 }
434 
435 SYSCALL_DEFINE1(chdir, const char __user *, filename)
436 {
437         struct path path;
438         int error;
439         unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
440 retry:
441         error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
442         if (error)
443                 goto out;
444 
445         error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
446         if (error)
447                 goto dput_and_out;
448 
449         set_fs_pwd(current->fs, &path);
450 
451 dput_and_out:
452         path_put(&path);
453         if (retry_estale(error, lookup_flags)) {
454                 lookup_flags |= LOOKUP_REVAL;
455                 goto retry;
456         }
457 out:
458         return error;
459 }
460 
461 SYSCALL_DEFINE1(fchdir, unsigned int, fd)
462 {
463         struct fd f = fdget_raw(fd);
464         struct inode *inode;
465         int error = -EBADF;
466 
467         error = -EBADF;
468         if (!f.file)
469                 goto out;
470 
471         inode = file_inode(f.file);
472 
473         error = -ENOTDIR;
474         if (!S_ISDIR(inode->i_mode))
475                 goto out_putf;
476 
477         error = inode_permission(inode, MAY_EXEC | MAY_CHDIR);
478         if (!error)
479                 set_fs_pwd(current->fs, &f.file->f_path);
480 out_putf:
481         fdput(f);
482 out:
483         return error;
484 }
485 
486 SYSCALL_DEFINE1(chroot, const char __user *, filename)
487 {
488         struct path path;
489         int error;
490         unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
491 retry:
492         error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
493         if (error)
494                 goto out;
495 
496         error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
497         if (error)
498                 goto dput_and_out;
499 
500         error = -EPERM;
501         if (!ns_capable(current_user_ns(), CAP_SYS_CHROOT))
502                 goto dput_and_out;
503         error = security_path_chroot(&path);
504         if (error)
505                 goto dput_and_out;
506 
507         set_fs_root(current->fs, &path);
508         error = 0;
509 dput_and_out:
510         path_put(&path);
511         if (retry_estale(error, lookup_flags)) {
512                 lookup_flags |= LOOKUP_REVAL;
513                 goto retry;
514         }
515 out:
516         return error;
517 }
518 
519 static int chmod_common(const struct path *path, umode_t mode)
520 {
521         struct inode *inode = path->dentry->d_inode;
522         struct inode *delegated_inode = NULL;
523         struct iattr newattrs;
524         int error;
525 
526         error = mnt_want_write(path->mnt);
527         if (error)
528                 return error;
529 retry_deleg:
530         inode_lock(inode);
531         error = security_path_chmod(path, mode);
532         if (error)
533                 goto out_unlock;
534         newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
535         newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
536         error = notify_change(path->dentry, &newattrs, &delegated_inode);
537 out_unlock:
538         inode_unlock(inode);
539         if (delegated_inode) {
540                 error = break_deleg_wait(&delegated_inode);
541                 if (!error)
542                         goto retry_deleg;
543         }
544         mnt_drop_write(path->mnt);
545         return error;
546 }
547 
548 SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode)
549 {
550         struct fd f = fdget(fd);
551         int err = -EBADF;
552 
553         if (f.file) {
554                 audit_file(f.file);
555                 err = chmod_common(&f.file->f_path, mode);
556                 fdput(f);
557         }
558         return err;
559 }
560 
561 SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename, umode_t, mode)
562 {
563         struct path path;
564         int error;
565         unsigned int lookup_flags = LOOKUP_FOLLOW;
566 retry:
567         error = user_path_at(dfd, filename, lookup_flags, &path);
568         if (!error) {
569                 error = chmod_common(&path, mode);
570                 path_put(&path);
571                 if (retry_estale(error, lookup_flags)) {
572                         lookup_flags |= LOOKUP_REVAL;
573                         goto retry;
574                 }
575         }
576         return error;
577 }
578 
579 SYSCALL_DEFINE2(chmod, const char __user *, filename, umode_t, mode)
580 {
581         return sys_fchmodat(AT_FDCWD, filename, mode);
582 }
583 
584 static int chown_common(const struct path *path, uid_t user, gid_t group)
585 {
586         struct inode *inode = path->dentry->d_inode;
587         struct inode *delegated_inode = NULL;
588         int error;
589         struct iattr newattrs;
590         kuid_t uid;
591         kgid_t gid;
592 
593         uid = make_kuid(current_user_ns(), user);
594         gid = make_kgid(current_user_ns(), group);
595 
596 retry_deleg:
597         newattrs.ia_valid =  ATTR_CTIME;
598         if (user != (uid_t) -1) {
599                 if (!uid_valid(uid))
600                         return -EINVAL;
601                 newattrs.ia_valid |= ATTR_UID;
602                 newattrs.ia_uid = uid;
603         }
604         if (group != (gid_t) -1) {
605                 if (!gid_valid(gid))
606                         return -EINVAL;
607                 newattrs.ia_valid |= ATTR_GID;
608                 newattrs.ia_gid = gid;
609         }
610         if (!S_ISDIR(inode->i_mode))
611                 newattrs.ia_valid |=
612                         ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_KILL_PRIV;
613         inode_lock(inode);
614         error = security_path_chown(path, uid, gid);
615         if (!error)
616                 error = notify_change(path->dentry, &newattrs, &delegated_inode);
617         inode_unlock(inode);
618         if (delegated_inode) {
619                 error = break_deleg_wait(&delegated_inode);
620                 if (!error)
621                         goto retry_deleg;
622         }
623         return error;
624 }
625 
626 SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user,
627                 gid_t, group, int, flag)
628 {
629         struct path path;
630         int error = -EINVAL;
631         int lookup_flags;
632 
633         if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
634                 goto out;
635 
636         lookup_flags = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
637         if (flag & AT_EMPTY_PATH)
638                 lookup_flags |= LOOKUP_EMPTY;
639 retry:
640         error = user_path_at(dfd, filename, lookup_flags, &path);
641         if (error)
642                 goto out;
643         error = mnt_want_write(path.mnt);
644         if (error)
645                 goto out_release;
646         error = chown_common(&path, user, group);
647         mnt_drop_write(path.mnt);
648 out_release:
649         path_put(&path);
650         if (retry_estale(error, lookup_flags)) {
651                 lookup_flags |= LOOKUP_REVAL;
652                 goto retry;
653         }
654 out:
655         return error;
656 }
657 
658 SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group)
659 {
660         return sys_fchownat(AT_FDCWD, filename, user, group, 0);
661 }
662 
663 SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group)
664 {
665         return sys_fchownat(AT_FDCWD, filename, user, group,
666                             AT_SYMLINK_NOFOLLOW);
667 }
668 
669 SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group)
670 {
671         struct fd f = fdget(fd);
672         int error = -EBADF;
673 
674         if (!f.file)
675                 goto out;
676 
677         error = mnt_want_write_file(f.file);
678         if (error)
679                 goto out_fput;
680         audit_file(f.file);
681         error = chown_common(&f.file->f_path, user, group);
682         mnt_drop_write_file(f.file);
683 out_fput:
684         fdput(f);
685 out:
686         return error;
687 }
688 
689 int open_check_o_direct(struct file *f)
690 {
691         /* NB: we're sure to have correct a_ops only after f_op->open */
692         if (f->f_flags & O_DIRECT) {
693                 if (!f->f_mapping->a_ops || !f->f_mapping->a_ops->direct_IO)
694                         return -EINVAL;
695         }
696         return 0;
697 }
698 
699 static int do_dentry_open(struct file *f,
700                           struct inode *inode,
701                           int (*open)(struct inode *, struct file *),
702                           const struct cred *cred)
703 {
704         static const struct file_operations empty_fops = {};
705         int error;
706 
707         f->f_mode = OPEN_FMODE(f->f_flags) | FMODE_LSEEK |
708                                 FMODE_PREAD | FMODE_PWRITE;
709 
710         path_get(&f->f_path);
711         f->f_inode = inode;
712         f->f_mapping = inode->i_mapping;
713 
714         if (unlikely(f->f_flags & O_PATH)) {
715                 f->f_mode = FMODE_PATH;
716                 f->f_op = &empty_fops;
717                 return 0;
718         }
719 
720         if (f->f_mode & FMODE_WRITE && !special_file(inode->i_mode)) {
721                 error = get_write_access(inode);
722                 if (unlikely(error))
723                         goto cleanup_file;
724                 error = __mnt_want_write(f->f_path.mnt);
725                 if (unlikely(error)) {
726                         put_write_access(inode);
727                         goto cleanup_file;
728                 }
729                 f->f_mode |= FMODE_WRITER;
730         }
731 
732         /* POSIX.1-2008/SUSv4 Section XSI 2.9.7 */
733         if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode))
734                 f->f_mode |= FMODE_ATOMIC_POS;
735 
736         f->f_op = fops_get(inode->i_fop);
737         if (unlikely(WARN_ON(!f->f_op))) {
738                 error = -ENODEV;
739                 goto cleanup_all;
740         }
741 
742         error = security_file_open(f, cred);
743         if (error)
744                 goto cleanup_all;
745 
746         error = break_lease(locks_inode(f), f->f_flags);
747         if (error)
748                 goto cleanup_all;
749 
750         if (!open)
751                 open = f->f_op->open;
752         if (open) {
753                 error = open(inode, f);
754                 if (error)
755                         goto cleanup_all;
756         }
757         if ((f->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
758                 i_readcount_inc(inode);
759         if ((f->f_mode & FMODE_READ) &&
760              likely(f->f_op->read || f->f_op->read_iter))
761                 f->f_mode |= FMODE_CAN_READ;
762         if ((f->f_mode & FMODE_WRITE) &&
763              likely(f->f_op->write || f->f_op->write_iter))
764                 f->f_mode |= FMODE_CAN_WRITE;
765 
766         f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
767 
768         file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);
769 
770         return 0;
771 
772 cleanup_all:
773         fops_put(f->f_op);
774         if (f->f_mode & FMODE_WRITER) {
775                 put_write_access(inode);
776                 __mnt_drop_write(f->f_path.mnt);
777         }
778 cleanup_file:
779         path_put(&f->f_path);
780         f->f_path.mnt = NULL;
781         f->f_path.dentry = NULL;
782         f->f_inode = NULL;
783         return error;
784 }
785 
786 /**
787  * finish_open - finish opening a file
788  * @file: file pointer
789  * @dentry: pointer to dentry
790  * @open: open callback
791  * @opened: state of open
792  *
793  * This can be used to finish opening a file passed to i_op->atomic_open().
794  *
795  * If the open callback is set to NULL, then the standard f_op->open()
796  * filesystem callback is substituted.
797  *
798  * NB: the dentry reference is _not_ consumed.  If, for example, the dentry is
799  * the return value of d_splice_alias(), then the caller needs to perform dput()
800  * on it after finish_open().
801  *
802  * On successful return @file is a fully instantiated open file.  After this, if
803  * an error occurs in ->atomic_open(), it needs to clean up with fput().
804  *
805  * Returns zero on success or -errno if the open failed.
806  */
807 int finish_open(struct file *file, struct dentry *dentry,
808                 int (*open)(struct inode *, struct file *),
809                 int *opened)
810 {
811         int error;
812         BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */
813 
814         file->f_path.dentry = dentry;
815         error = do_dentry_open(file, d_backing_inode(dentry), open,
816                                current_cred());
817         if (!error)
818                 *opened |= FILE_OPENED;
819 
820         return error;
821 }
822 EXPORT_SYMBOL(finish_open);
823 
824 /**
825  * finish_no_open - finish ->atomic_open() without opening the file
826  *
827  * @file: file pointer
828  * @dentry: dentry or NULL (as returned from ->lookup())
829  *
830  * This can be used to set the result of a successful lookup in ->atomic_open().
831  *
832  * NB: unlike finish_open() this function does consume the dentry reference and
833  * the caller need not dput() it.
834  *
835  * Returns "1" which must be the return value of ->atomic_open() after having
836  * called this function.
837  */
838 int finish_no_open(struct file *file, struct dentry *dentry)
839 {
840         file->f_path.dentry = dentry;
841         return 1;
842 }
843 EXPORT_SYMBOL(finish_no_open);
844 
845 char *file_path(struct file *filp, char *buf, int buflen)
846 {
847         return d_path(&filp->f_path, buf, buflen);
848 }
849 EXPORT_SYMBOL(file_path);
850 
851 /**
852  * vfs_open - open the file at the given path
853  * @path: path to open
854  * @file: newly allocated file with f_flag initialized
855  * @cred: credentials to use
856  */
857 int vfs_open(const struct path *path, struct file *file,
858              const struct cred *cred)
859 {
860         struct dentry *dentry = d_real(path->dentry, NULL, file->f_flags);
861 
862         if (IS_ERR(dentry))
863                 return PTR_ERR(dentry);
864 
865         file->f_path = *path;
866         return do_dentry_open(file, d_backing_inode(dentry), NULL, cred);
867 }
868 
869 struct file *dentry_open(const struct path *path, int flags,
870                          const struct cred *cred)
871 {
872         int error;
873         struct file *f;
874 
875         validate_creds(cred);
876 
877         /* We must always pass in a valid mount pointer. */
878         BUG_ON(!path->mnt);
879 
880         f = get_empty_filp();
881         if (!IS_ERR(f)) {
882                 f->f_flags = flags;
883                 error = vfs_open(path, f, cred);
884                 if (!error) {
885                         /* from now on we need fput() to dispose of f */
886                         error = open_check_o_direct(f);
887                         if (error) {
888                                 fput(f);
889                                 f = ERR_PTR(error);
890                         }
891                 } else { 
892                         put_filp(f);
893                         f = ERR_PTR(error);
894                 }
895         }
896         return f;
897 }
898 EXPORT_SYMBOL(dentry_open);
899 
900 static inline int build_open_flags(int flags, umode_t mode, struct open_flags *op)
901 {
902         int lookup_flags = 0;
903         int acc_mode = ACC_MODE(flags);
904 
905         if (flags & (O_CREAT | __O_TMPFILE))
906                 op->mode = (mode & S_IALLUGO) | S_IFREG;
907         else
908                 op->mode = 0;
909 
910         /* Must never be set by userspace */
911         flags &= ~FMODE_NONOTIFY & ~O_CLOEXEC;
912 
913         /*
914          * O_SYNC is implemented as __O_SYNC|O_DSYNC.  As many places only
915          * check for O_DSYNC if the need any syncing at all we enforce it's
916          * always set instead of having to deal with possibly weird behaviour
917          * for malicious applications setting only __O_SYNC.
918          */
919         if (flags & __O_SYNC)
920                 flags |= O_DSYNC;
921 
922         if (flags & __O_TMPFILE) {
923                 if ((flags & O_TMPFILE_MASK) != O_TMPFILE)
924                         return -EINVAL;
925                 if (!(acc_mode & MAY_WRITE))
926                         return -EINVAL;
927         } else if (flags & O_PATH) {
928                 /*
929                  * If we have O_PATH in the open flag. Then we
930                  * cannot have anything other than the below set of flags
931                  */
932                 flags &= O_DIRECTORY | O_NOFOLLOW | O_PATH;
933                 acc_mode = 0;
934         }
935 
936         op->open_flag = flags;
937 
938         /* O_TRUNC implies we need access checks for write permissions */
939         if (flags & O_TRUNC)
940                 acc_mode |= MAY_WRITE;
941 
942         /* Allow the LSM permission hook to distinguish append
943            access from general write access. */
944         if (flags & O_APPEND)
945                 acc_mode |= MAY_APPEND;
946 
947         op->acc_mode = acc_mode;
948 
949         op->intent = flags & O_PATH ? 0 : LOOKUP_OPEN;
950 
951         if (flags & O_CREAT) {
952                 op->intent |= LOOKUP_CREATE;
953                 if (flags & O_EXCL)
954                         op->intent |= LOOKUP_EXCL;
955         }
956 
957         if (flags & O_DIRECTORY)
958                 lookup_flags |= LOOKUP_DIRECTORY;
959         if (!(flags & O_NOFOLLOW))
960                 lookup_flags |= LOOKUP_FOLLOW;
961         op->lookup_flags = lookup_flags;
962         return 0;
963 }
964 
965 /**
966  * file_open_name - open file and return file pointer
967  *
968  * @name:       struct filename containing path to open
969  * @flags:      open flags as per the open(2) second argument
970  * @mode:       mode for the new file if O_CREAT is set, else ignored
971  *
972  * This is the helper to open a file from kernelspace if you really
973  * have to.  But in generally you should not do this, so please move
974  * along, nothing to see here..
975  */
976 struct file *file_open_name(struct filename *name, int flags, umode_t mode)
977 {
978         struct open_flags op;
979         int err = build_open_flags(flags, mode, &op);
980         return err ? ERR_PTR(err) : do_filp_open(AT_FDCWD, name, &op);
981 }
982 
983 /**
984  * filp_open - open file and return file pointer
985  *
986  * @filename:   path to open
987  * @flags:      open flags as per the open(2) second argument
988  * @mode:       mode for the new file if O_CREAT is set, else ignored
989  *
990  * This is the helper to open a file from kernelspace if you really
991  * have to.  But in generally you should not do this, so please move
992  * along, nothing to see here..
993  */
994 struct file *filp_open(const char *filename, int flags, umode_t mode)
995 {
996         struct filename *name = getname_kernel(filename);
997         struct file *file = ERR_CAST(name);
998         
999         if (!IS_ERR(name)) {
1000                 file = file_open_name(name, flags, mode);
1001                 putname(name);
1002         }
1003         return file;
1004 }
1005 EXPORT_SYMBOL(filp_open);
1006 
1007 struct file *file_open_root(struct dentry *dentry, struct vfsmount *mnt,
1008                             const char *filename, int flags, umode_t mode)
1009 {
1010         struct open_flags op;
1011         int err = build_open_flags(flags, mode, &op);
1012         if (err)
1013                 return ERR_PTR(err);
1014         return do_file_open_root(dentry, mnt, filename, &op);
1015 }
1016 EXPORT_SYMBOL(file_open_root);
1017 
1018 struct file *filp_clone_open(struct file *oldfile)
1019 {
1020         struct file *file;
1021         int retval;
1022 
1023         file = get_empty_filp();
1024         if (IS_ERR(file))
1025                 return file;
1026 
1027         file->f_flags = oldfile->f_flags;
1028         retval = vfs_open(&oldfile->f_path, file, oldfile->f_cred);
1029         if (retval) {
1030                 put_filp(file);
1031                 return ERR_PTR(retval);
1032         }
1033 
1034         return file;
1035 }
1036 EXPORT_SYMBOL(filp_clone_open);
1037 
1038 long do_sys_open(int dfd, const char __user *filename, int flags, umode_t mode)
1039 {
1040         struct open_flags op;
1041         int fd = build_open_flags(flags, mode, &op);
1042         struct filename *tmp;
1043 
1044         if (fd)
1045                 return fd;
1046 
1047         tmp = getname(filename);
1048         if (IS_ERR(tmp))
1049                 return PTR_ERR(tmp);
1050 
1051         fd = get_unused_fd_flags(flags);
1052         if (fd >= 0) {
1053                 struct file *f = do_filp_open(dfd, tmp, &op);
1054                 if (IS_ERR(f)) {
1055                         put_unused_fd(fd);
1056                         fd = PTR_ERR(f);
1057                 } else {
1058                         fsnotify_open(f);
1059                         fd_install(fd, f);
1060                 }
1061         }
1062         putname(tmp);
1063         return fd;
1064 }
1065 
1066 SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)
1067 {
1068         if (force_o_largefile())
1069                 flags |= O_LARGEFILE;
1070 
1071         return do_sys_open(AT_FDCWD, filename, flags, mode);
1072 }
1073 
1074 SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags,
1075                 umode_t, mode)
1076 {
1077         if (force_o_largefile())
1078                 flags |= O_LARGEFILE;
1079 
1080         return do_sys_open(dfd, filename, flags, mode);
1081 }
1082 
1083 #ifndef __alpha__
1084 
1085 /*
1086  * For backward compatibility?  Maybe this should be moved
1087  * into arch/i386 instead?
1088  */
1089 SYSCALL_DEFINE2(creat, const char __user *, pathname, umode_t, mode)
1090 {
1091         return sys_open(pathname, O_CREAT | O_WRONLY | O_TRUNC, mode);
1092 }
1093 
1094 #endif
1095 
1096 /*
1097  * "id" is the POSIX thread ID. We use the
1098  * files pointer for this..
1099  */
1100 int filp_close(struct file *filp, fl_owner_t id)
1101 {
1102         int retval = 0;
1103 
1104         if (!file_count(filp)) {
1105                 printk(KERN_ERR "VFS: Close: file count is 0\n");
1106                 return 0;
1107         }
1108 
1109         if (filp->f_op->flush)
1110                 retval = filp->f_op->flush(filp, id);
1111 
1112         if (likely(!(filp->f_mode & FMODE_PATH))) {
1113                 dnotify_flush(filp, id);
1114                 locks_remove_posix(filp, id);
1115         }
1116         fput(filp);
1117         return retval;
1118 }
1119 
1120 EXPORT_SYMBOL(filp_close);
1121 
1122 /*
1123  * Careful here! We test whether the file pointer is NULL before
1124  * releasing the fd. This ensures that one clone task can't release
1125  * an fd while another clone is opening it.
1126  */
1127 SYSCALL_DEFINE1(close, unsigned int, fd)
1128 {
1129         int retval = __close_fd(current->files, fd);
1130 
1131         /* can't restart close syscall because file table entry was cleared */
1132         if (unlikely(retval == -ERESTARTSYS ||
1133                      retval == -ERESTARTNOINTR ||
1134                      retval == -ERESTARTNOHAND ||
1135                      retval == -ERESTART_RESTARTBLOCK))
1136                 retval = -EINTR;
1137 
1138         return retval;
1139 }
1140 EXPORT_SYMBOL(sys_close);
1141 
1142 /*
1143  * This routine simulates a hangup on the tty, to arrange that users
1144  * are given clean terminals at login time.
1145  */
1146 SYSCALL_DEFINE0(vhangup)
1147 {
1148         if (capable(CAP_SYS_TTY_CONFIG)) {
1149                 tty_vhangup_self();
1150                 return 0;
1151         }
1152         return -EPERM;
1153 }
1154 
1155 /*
1156  * Called when an inode is about to be open.
1157  * We use this to disallow opening large files on 32bit systems if
1158  * the caller didn't specify O_LARGEFILE.  On 64bit systems we force
1159  * on this flag in sys_open.
1160  */
1161 int generic_file_open(struct inode * inode, struct file * filp)
1162 {
1163         if (!(filp->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS)
1164                 return -EOVERFLOW;
1165         return 0;
1166 }
1167 
1168 EXPORT_SYMBOL(generic_file_open);
1169 
1170 /*
1171  * This is used by subsystems that don't want seekable
1172  * file descriptors. The function is not supposed to ever fail, the only
1173  * reason it returns an 'int' and not 'void' is so that it can be plugged
1174  * directly into file_operations structure.
1175  */
1176 int nonseekable_open(struct inode *inode, struct file *filp)
1177 {
1178         filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);
1179         return 0;
1180 }
1181 
1182 EXPORT_SYMBOL(nonseekable_open);
1183 

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