fs/open.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  linux/fs/open.c
   4  *
   5  *  Copyright (C) 1991, 1992  Linus Torvalds
   6  */
   7
   8 #include <linux/string.h>
   9 #include <linux/mm.h>
  10 #include <linux/file.h>
  11 #include <linux/fdtable.h>
  12 #include <linux/fsnotify.h>
  13 #include <linux/module.h>
  14 #include <linux/tty.h>
  15 #include <linux/namei.h>
  16 #include <linux/backing-dev.h>
  17 #include <linux/capability.h>
  18 #include <linux/securebits.h>
  19 #include <linux/security.h>
  20 #include <linux/mount.h>
  21 #include <linux/fcntl.h>
  22 #include <linux/slab.h>
  23 #include <linux/uaccess.h>
  24 #include <linux/fs.h>
  25 #include <linux/personality.h>
  26 #include <linux/pagemap.h>
  27 #include <linux/syscalls.h>
  28 #include <linux/rcupdate.h>
  29 #include <linux/audit.h>
  30 #include <linux/falloc.h>
  31 #include <linux/fs_struct.h>
  32 #include <linux/ima.h>
  33 #include <linux/dnotify.h>
  34 #include <linux/compat.h>
  35 #include <linux/mnt_idmapping.h>
  36
  37 #include "internal.h"
  38
  39 int do_truncate(struct user_namespace *mnt_userns, struct dentry *dentry,
  40                 loff_t length, unsigned int time_attrs, struct file *filp)
  41 {
  42         int ret;
  43         struct iattr newattrs;
  44
  45         /* Not pretty: "inode->i_size" shouldn't really be signed. But it is. */
  46         if (length < 0)
  47                 return -EINVAL;
  48
  49         newattrs.ia_size = length;
  50         newattrs.ia_valid = ATTR_SIZE | time_attrs;
  51         if (filp) {
  52                 newattrs.ia_file = filp;
  53                 newattrs.ia_valid |= ATTR_FILE;
  54         }
  55
  56         /* Remove suid, sgid, and file capabilities on truncate too */
  57         ret = dentry_needs_remove_privs(dentry);
  58         if (ret < 0)
  59                 return ret;
  60         if (ret)
  61                 newattrs.ia_valid |= ret | ATTR_FORCE;
  62
  63         inode_lock(dentry->d_inode);
  64         /* Note any delegations or leases have already been broken: */
  65         ret = notify_change(mnt_userns, dentry, &newattrs, NULL);
  66         inode_unlock(dentry->d_inode);
  67         return ret;
  68 }
  69
  70 long vfs_truncate(const struct path *path, loff_t length)
  71 {
  72         struct user_namespace *mnt_userns;
  73         struct inode *inode;
  74         long error;
  75
  76         inode = path->dentry->d_inode;
  77
  78         /* For directories it's -EISDIR, for other non-regulars - -EINVAL */
  79         if (S_ISDIR(inode->i_mode))
  80                 return -EISDIR;
  81         if (!S_ISREG(inode->i_mode))
  82                 return -EINVAL;
  83
  84         error = mnt_want_write(path->mnt);
  85         if (error)
  86                 goto out;
  87
  88         mnt_userns = mnt_user_ns(path->mnt);
  89         error = inode_permission(mnt_userns, inode, MAY_WRITE);
  90         if (error)
  91                 goto mnt_drop_write_and_out;
  92
  93         error = -EPERM;
  94         if (IS_APPEND(inode))
  95                 goto mnt_drop_write_and_out;
  96
  97         error = get_write_access(inode);
  98         if (error)
  99                 goto mnt_drop_write_and_out;
 100
 101         /*
 102          * Make sure that there are no leases.  get_write_access() protects
 103          * against the truncate racing with a lease-granting setlease().
 104          */
 105         error = break_lease(inode, O_WRONLY);
 106         if (error)
 107                 goto put_write_and_out;
 108
 109         error = security_path_truncate(path);
 110         if (!error)
 111                 error = do_truncate(mnt_userns, path->dentry, length, 0, NULL);
 112
 113 put_write_and_out:
 114         put_write_access(inode);
 115 mnt_drop_write_and_out:
 116         mnt_drop_write(path->mnt);
 117 out:
 118         return error;
 119 }
 120 EXPORT_SYMBOL_GPL(vfs_truncate);
 121
 122 long do_sys_truncate(const char __user *pathname, loff_t length)
 123 {
 124         unsigned int lookup_flags = LOOKUP_FOLLOW;
 125         struct path path;
 126         int error;
 127
 128         if (length < 0) /* sorry, but loff_t says... */
 129                 return -EINVAL;
 130
 131 retry:
 132         error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
 133         if (!error) {
 134                 error = vfs_truncate(&path, length);
 135                 path_put(&path);
 136         }
 137         if (retry_estale(error, lookup_flags)) {
 138                 lookup_flags |= LOOKUP_REVAL;
 139                 goto retry;
 140         }
 141         return error;
 142 }
 143
 144 SYSCALL_DEFINE2(truncate, const char __user *, path, long, length)
 145 {
 146         return do_sys_truncate(path, length);
 147 }
 148
 149 #ifdef CONFIG_COMPAT
 150 COMPAT_SYSCALL_DEFINE2(truncate, const char __user *, path, compat_off_t, length)
 151 {
 152         return do_sys_truncate(path, length);
 153 }
 154 #endif
 155
 156 long do_sys_ftruncate(unsigned int fd, loff_t length, int small)
 157 {
 158         struct inode *inode;
 159         struct dentry *dentry;
 160         struct fd f;
 161         int error;
 162
 163         error = -EINVAL;
 164         if (length < 0)
 165                 goto out;
 166         error = -EBADF;
 167         f = fdget(fd);
 168         if (!f.file)
 169                 goto out;
 170
 171         /* explicitly opened as large or we are on 64-bit box */
 172         if (f.file->f_flags & O_LARGEFILE)
 173                 small = 0;
 174
 175         dentry = f.file->f_path.dentry;
 176         inode = dentry->d_inode;
 177         error = -EINVAL;
 178         if (!S_ISREG(inode->i_mode) || !(f.file->f_mode & FMODE_WRITE))
 179                 goto out_putf;
 180
 181         error = -EINVAL;
 182         /* Cannot ftruncate over 2^31 bytes without large file support */
 183         if (small && length > MAX_NON_LFS)
 184                 goto out_putf;
 185
 186         error = -EPERM;
 187         /* Check IS_APPEND on real upper inode */
 188         if (IS_APPEND(file_inode(f.file)))
 189                 goto out_putf;
 190         sb_start_write(inode->i_sb);
 191         error = security_path_truncate(&f.file->f_path);
 192         if (!error)
 193                 error = do_truncate(file_mnt_user_ns(f.file), dentry, length,
 194                                     ATTR_MTIME | ATTR_CTIME, f.file);
 195         sb_end_write(inode->i_sb);
 196 out_putf:
 197         fdput(f);
 198 out:
 199         return error;
 200 }
 201
 202 SYSCALL_DEFINE2(ftruncate, unsigned int, fd, unsigned long, length)
 203 {
 204         return do_sys_ftruncate(fd, length, 1);
 205 }
 206
 207 #ifdef CONFIG_COMPAT
 208 COMPAT_SYSCALL_DEFINE2(ftruncate, unsigned int, fd, compat_ulong_t, length)
 209 {
 210         return do_sys_ftruncate(fd, length, 1);
 211 }
 212 #endif
 213
 214 /* LFS versions of truncate are only needed on 32 bit machines */
 215 #if BITS_PER_LONG == 32
 216 SYSCALL_DEFINE2(truncate64, const char __user *, path, loff_t, length)
 217 {
 218         return do_sys_truncate(path, length);
 219 }
 220
 221 SYSCALL_DEFINE2(ftruncate64, unsigned int, fd, loff_t, length)
 222 {
 223         return do_sys_ftruncate(fd, length, 0);
 224 }
 225 #endif /* BITS_PER_LONG == 32 */
 226
 227
 228 int vfs_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
 229 {
 230         struct inode *inode = file_inode(file);
 231         long ret;
 232
 233         if (offset < 0 || len <= 0)
 234                 return -EINVAL;
 235
 236         /* Return error if mode is not supported */
 237         if (mode & ~FALLOC_FL_SUPPORTED_MASK)
 238                 return -EOPNOTSUPP;
 239
 240         /* Punch hole and zero range are mutually exclusive */
 241         if ((mode & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE)) ==
 242             (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE))
 243                 return -EOPNOTSUPP;
 244
 245         /* Punch hole must have keep size set */
 246         if ((mode & FALLOC_FL_PUNCH_HOLE) &&
 247             !(mode & FALLOC_FL_KEEP_SIZE))
 248                 return -EOPNOTSUPP;
 249
 250         /* Collapse range should only be used exclusively. */
 251         if ((mode & FALLOC_FL_COLLAPSE_RANGE) &&
 252             (mode & ~FALLOC_FL_COLLAPSE_RANGE))
 253                 return -EINVAL;
 254
 255         /* Insert range should only be used exclusively. */
 256         if ((mode & FALLOC_FL_INSERT_RANGE) &&
 257             (mode & ~FALLOC_FL_INSERT_RANGE))
 258                 return -EINVAL;
 259
 260         /* Unshare range should only be used with allocate mode. */
 261         if ((mode & FALLOC_FL_UNSHARE_RANGE) &&
 262             (mode & ~(FALLOC_FL_UNSHARE_RANGE | FALLOC_FL_KEEP_SIZE)))
 263                 return -EINVAL;
 264
 265         if (!(file->f_mode & FMODE_WRITE))
 266                 return -EBADF;
 267
 268         /*
 269          * We can only allow pure fallocate on append only files
 270          */
 271         if ((mode & ~FALLOC_FL_KEEP_SIZE) && IS_APPEND(inode))
 272                 return -EPERM;
 273
 274         if (IS_IMMUTABLE(inode))
 275                 return -EPERM;
 276
 277         /*
 278          * We cannot allow any fallocate operation on an active swapfile
 279          */
 280         if (IS_SWAPFILE(inode))
 281                 return -ETXTBSY;
 282
 283         /*
 284          * Revalidate the write permissions, in case security policy has
 285          * changed since the files were opened.
 286          */
 287         ret = security_file_permission(file, MAY_WRITE);
 288         if (ret)
 289                 return ret;
 290
 291         if (S_ISFIFO(inode->i_mode))
 292                 return -ESPIPE;
 293
 294         if (S_ISDIR(inode->i_mode))
 295                 return -EISDIR;
 296
 297         if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
 298                 return -ENODEV;
 299
 300         /* Check for wrap through zero too */
 301         if (((offset + len) > inode->i_sb->s_maxbytes) || ((offset + len) < 0))
 302                 return -EFBIG;
 303
 304         if (!file->f_op->fallocate)
 305                 return -EOPNOTSUPP;
 306
 307         file_start_write(file);
 308         ret = file->f_op->fallocate(file, mode, offset, len);
 309
 310         /*
 311          * Create inotify and fanotify events.
 312          *
 313          * To keep the logic simple always create events if fallocate succeeds.
 314          * This implies that events are even created if the file size remains
 315          * unchanged, e.g. when using flag FALLOC_FL_KEEP_SIZE.
 316          */
 317         if (ret == 0)
 318                 fsnotify_modify(file);
 319
 320         file_end_write(file);
 321         return ret;
 322 }
 323 EXPORT_SYMBOL_GPL(vfs_fallocate);
 324
 325 int ksys_fallocate(int fd, int mode, loff_t offset, loff_t len)
 326 {
 327         struct fd f = fdget(fd);
 328         int error = -EBADF;
 329
 330         if (f.file) {
 331                 error = vfs_fallocate(f.file, mode, offset, len);
 332                 fdput(f);
 333         }
 334         return error;
 335 }
 336
 337 SYSCALL_DEFINE4(fallocate, int, fd, int, mode, loff_t, offset, loff_t, len)
 338 {
 339         return ksys_fallocate(fd, mode, offset, len);
 340 }
 341
 342 /*
 343  * access() needs to use the real uid/gid, not the effective uid/gid.
 344  * We do this by temporarily clearing all FS-related capabilities and
 345  * switching the fsuid/fsgid around to the real ones.
 346  */
 347 static const struct cred *access_override_creds(void)
 348 {
 349         const struct cred *old_cred;
 350         struct cred *override_cred;
 351
 352         override_cred = prepare_creds();
 353         if (!override_cred)
 354                 return NULL;
 355
 356         override_cred->fsuid = override_cred->uid;
 357         override_cred->fsgid = override_cred->gid;
 358
 359         if (!issecure(SECURE_NO_SETUID_FIXUP)) {
 360                 /* Clear the capabilities if we switch to a non-root user */
 361                 kuid_t root_uid = make_kuid(override_cred->user_ns, 0);
 362                 if (!uid_eq(override_cred->uid, root_uid))
 363                         cap_clear(override_cred->cap_effective);
 364                 else
 365                         override_cred->cap_effective =
 366                                 override_cred->cap_permitted;
 367         }
 368
 369         /*
 370          * The new set of credentials can *only* be used in
 371          * task-synchronous circumstances, and does not need
 372          * RCU freeing, unless somebody then takes a separate
 373          * reference to it.
 374          *
 375          * NOTE! This is _only_ true because this credential
 376          * is used purely for override_creds() that installs
 377          * it as the subjective cred. Other threads will be
 378          * accessing ->real_cred, not the subjective cred.
 379          *
 380          * If somebody _does_ make a copy of this (using the
 381          * 'get_current_cred()' function), that will clear the
 382          * non_rcu field, because now that other user may be
 383          * expecting RCU freeing. But normal thread-synchronous
 384          * cred accesses will keep things non-RCY.
 385          */
 386         override_cred->non_rcu = 1;
 387
 388         old_cred = override_creds(override_cred);
 389
 390         /* override_cred() gets its own ref */
 391         put_cred(override_cred);
 392
 393         return old_cred;
 394 }
 395
 396 static long do_faccessat(int dfd, const char __user *filename, int mode, int flags)
 397 {
 398         struct path path;
 399         struct inode *inode;
 400         int res;
 401         unsigned int lookup_flags = LOOKUP_FOLLOW;
 402         const struct cred *old_cred = NULL;
 403
 404         if (mode & ~S_IRWXO)    /* where's F_OK, X_OK, W_OK, R_OK? */
 405                 return -EINVAL;
 406
 407         if (flags & ~(AT_EACCESS | AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH))
 408                 return -EINVAL;
 409
 410         if (flags & AT_SYMLINK_NOFOLLOW)
 411                 lookup_flags &= ~LOOKUP_FOLLOW;
 412         if (flags & AT_EMPTY_PATH)
 413                 lookup_flags |= LOOKUP_EMPTY;
 414
 415         if (!(flags & AT_EACCESS)) {
 416                 old_cred = access_override_creds();
 417                 if (!old_cred)
 418                         return -ENOMEM;
 419         }
 420
 421 retry:
 422         res = user_path_at(dfd, filename, lookup_flags, &path);
 423         if (res)
 424                 goto out;
 425
 426         inode = d_backing_inode(path.dentry);
 427
 428         if ((mode & MAY_EXEC) && S_ISREG(inode->i_mode)) {
 429                 /*
 430                  * MAY_EXEC on regular files is denied if the fs is mounted
 431                  * with the "noexec" flag.
 432                  */
 433                 res = -EACCES;
 434                 if (path_noexec(&path))
 435                         goto out_path_release;
 436         }
 437
 438         res = inode_permission(mnt_user_ns(path.mnt), inode, mode | MAY_ACCESS);
 439         /* SuS v2 requires we report a read only fs too */
 440         if (res || !(mode & S_IWOTH) || special_file(inode->i_mode))
 441                 goto out_path_release;
 442         /*
 443          * This is a rare case where using __mnt_is_readonly()
 444          * is OK without a mnt_want/drop_write() pair.  Since
 445          * no actual write to the fs is performed here, we do
 446          * not need to telegraph to that to anyone.
 447          *
 448          * By doing this, we accept that this access is
 449          * inherently racy and know that the fs may change
 450          * state before we even see this result.
 451          */
 452         if (__mnt_is_readonly(path.mnt))
 453                 res = -EROFS;
 454
 455 out_path_release:
 456         path_put(&path);
 457         if (retry_estale(res, lookup_flags)) {
 458                 lookup_flags |= LOOKUP_REVAL;
 459                 goto retry;
 460         }
 461 out:
 462         if (old_cred)
 463                 revert_creds(old_cred);
 464
 465         return res;
 466 }
 467
 468 SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode)
 469 {
 470         return do_faccessat(dfd, filename, mode, 0);
 471 }
 472
 473 SYSCALL_DEFINE4(faccessat2, int, dfd, const char __user *, filename, int, mode,
 474                 int, flags)
 475 {
 476         return do_faccessat(dfd, filename, mode, flags);
 477 }
 478
 479 SYSCALL_DEFINE2(access, const char __user *, filename, int, mode)
 480 {
 481         return do_faccessat(AT_FDCWD, filename, mode, 0);
 482 }
 483
 484 SYSCALL_DEFINE1(chdir, const char __user *, filename)
 485 {
 486         struct path path;
 487         int error;
 488         unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
 489 retry:
 490         error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
 491         if (error)
 492                 goto out;
 493
 494         error = path_permission(&path, MAY_EXEC | MAY_CHDIR);
 495         if (error)
 496                 goto dput_and_out;
 497
 498         set_fs_pwd(current->fs, &path);
 499
 500 dput_and_out:
 501         path_put(&path);
 502         if (retry_estale(error, lookup_flags)) {
 503                 lookup_flags |= LOOKUP_REVAL;
 504                 goto retry;
 505         }
 506 out:
 507         return error;
 508 }
 509
 510 SYSCALL_DEFINE1(fchdir, unsigned int, fd)
 511 {
 512         struct fd f = fdget_raw(fd);
 513         int error;
 514
 515         error = -EBADF;
 516         if (!f.file)
 517                 goto out;
 518
 519         error = -ENOTDIR;
 520         if (!d_can_lookup(f.file->f_path.dentry))
 521                 goto out_putf;
 522
 523         error = file_permission(f.file, MAY_EXEC | MAY_CHDIR);
 524         if (!error)
 525                 set_fs_pwd(current->fs, &f.file->f_path);
 526 out_putf:
 527         fdput(f);
 528 out:
 529         return error;
 530 }
 531
 532 SYSCALL_DEFINE1(chroot, const char __user *, filename)
 533 {
 534         struct path path;
 535         int error;
 536         unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
 537 retry:
 538         error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
 539         if (error)
 540                 goto out;
 541
 542         error = path_permission(&path, MAY_EXEC | MAY_CHDIR);
 543         if (error)
 544                 goto dput_and_out;
 545
 546         error = -EPERM;
 547         if (!ns_capable(current_user_ns(), CAP_SYS_CHROOT))
 548                 goto dput_and_out;
 549         error = security_path_chroot(&path);
 550         if (error)
 551                 goto dput_and_out;
 552
 553         set_fs_root(current->fs, &path);
 554         error = 0;
 555 dput_and_out:
 556         path_put(&path);
 557         if (retry_estale(error, lookup_flags)) {
 558                 lookup_flags |= LOOKUP_REVAL;
 559                 goto retry;
 560         }
 561 out:
 562         return error;
 563 }
 564
 565 int chmod_common(const struct path *path, umode_t mode)
 566 {
 567         struct inode *inode = path->dentry->d_inode;
 568         struct inode *delegated_inode = NULL;
 569         struct iattr newattrs;
 570         int error;
 571
 572         error = mnt_want_write(path->mnt);
 573         if (error)
 574                 return error;
 575 retry_deleg:
 576         inode_lock(inode);
 577         error = security_path_chmod(path, mode);
 578         if (error)
 579                 goto out_unlock;
 580         newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
 581         newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
 582         error = notify_change(mnt_user_ns(path->mnt), path->dentry,
 583                               &newattrs, &delegated_inode);
 584 out_unlock:
 585         inode_unlock(inode);
 586         if (delegated_inode) {
 587                 error = break_deleg_wait(&delegated_inode);
 588                 if (!error)
 589                         goto retry_deleg;
 590         }
 591         mnt_drop_write(path->mnt);
 592         return error;
 593 }
 594
 595 int vfs_fchmod(struct file *file, umode_t mode)
 596 {
 597         audit_file(file);
 598         return chmod_common(&file->f_path, mode);
 599 }
 600
 601 SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode)
 602 {
 603         struct fd f = fdget(fd);
 604         int err = -EBADF;
 605
 606         if (f.file) {
 607                 err = vfs_fchmod(f.file, mode);
 608                 fdput(f);
 609         }
 610         return err;
 611 }
 612
 613 static int do_fchmodat(int dfd, const char __user *filename, umode_t mode)
 614 {
 615         struct path path;
 616         int error;
 617         unsigned int lookup_flags = LOOKUP_FOLLOW;
 618 retry:
 619         error = user_path_at(dfd, filename, lookup_flags, &path);
 620         if (!error) {
 621                 error = chmod_common(&path, mode);
 622                 path_put(&path);
 623                 if (retry_estale(error, lookup_flags)) {
 624                         lookup_flags |= LOOKUP_REVAL;
 625                         goto retry;
 626                 }
 627         }
 628         return error;
 629 }
 630
 631 SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename,
 632                 umode_t, mode)
 633 {
 634         return do_fchmodat(dfd, filename, mode);
 635 }
 636
 637 SYSCALL_DEFINE2(chmod, const char __user *, filename, umode_t, mode)
 638 {
 639         return do_fchmodat(AT_FDCWD, filename, mode);
 640 }
 641
 642 int chown_common(const struct path *path, uid_t user, gid_t group)
 643 {
 644         struct user_namespace *mnt_userns, *fs_userns;
 645         struct inode *inode = path->dentry->d_inode;
 646         struct inode *delegated_inode = NULL;
 647         int error;
 648         struct iattr newattrs;
 649         kuid_t uid;
 650         kgid_t gid;
 651
 652         uid = make_kuid(current_user_ns(), user);
 653         gid = make_kgid(current_user_ns(), group);
 654
 655         mnt_userns = mnt_user_ns(path->mnt);
 656         fs_userns = i_user_ns(inode);
 657         uid = mapped_kuid_user(mnt_userns, fs_userns, uid);
 658         gid = mapped_kgid_user(mnt_userns, fs_userns, gid);
 659
 660 retry_deleg:
 661         newattrs.ia_valid =  ATTR_CTIME;
 662         if (user != (uid_t) -1) {
 663                 if (!uid_valid(uid))
 664                         return -EINVAL;
 665                 newattrs.ia_valid |= ATTR_UID;
 666                 newattrs.ia_uid = uid;
 667         }
 668         if (group != (gid_t) -1) {
 669                 if (!gid_valid(gid))
 670                         return -EINVAL;
 671                 newattrs.ia_valid |= ATTR_GID;
 672                 newattrs.ia_gid = gid;
 673         }
 674         if (!S_ISDIR(inode->i_mode))
 675                 newattrs.ia_valid |=
 676                         ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_KILL_PRIV;
 677         inode_lock(inode);
 678         error = security_path_chown(path, uid, gid);
 679         if (!error)
 680                 error = notify_change(mnt_userns, path->dentry, &newattrs,
 681                                       &delegated_inode);
 682         inode_unlock(inode);
 683         if (delegated_inode) {
 684                 error = break_deleg_wait(&delegated_inode);
 685                 if (!error)
 686                         goto retry_deleg;
 687         }
 688         return error;
 689 }
 690
 691 int do_fchownat(int dfd, const char __user *filename, uid_t user, gid_t group,
 692                 int flag)
 693 {
 694         struct path path;
 695         int error = -EINVAL;
 696         int lookup_flags;
 697
 698         if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
 699                 goto out;
 700
 701         lookup_flags = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
 702         if (flag & AT_EMPTY_PATH)
 703                 lookup_flags |= LOOKUP_EMPTY;
 704 retry:
 705         error = user_path_at(dfd, filename, lookup_flags, &path);
 706         if (error)
 707                 goto out;
 708         error = mnt_want_write(path.mnt);
 709         if (error)
 710                 goto out_release;
 711         error = chown_common(&path, user, group);
 712         mnt_drop_write(path.mnt);
 713 out_release:
 714         path_put(&path);
 715         if (retry_estale(error, lookup_flags)) {
 716                 lookup_flags |= LOOKUP_REVAL;
 717                 goto retry;
 718         }
 719 out:
 720         return error;
 721 }
 722
 723 SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user,
 724                 gid_t, group, int, flag)
 725 {
 726         return do_fchownat(dfd, filename, user, group, flag);
 727 }
 728
 729 SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group)
 730 {
 731         return do_fchownat(AT_FDCWD, filename, user, group, 0);
 732 }
 733
 734 SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group)
 735 {
 736         return do_fchownat(AT_FDCWD, filename, user, group,
 737                            AT_SYMLINK_NOFOLLOW);
 738 }
 739
 740 int vfs_fchown(struct file *file, uid_t user, gid_t group)
 741 {
 742         int error;
 743
 744         error = mnt_want_write_file(file);
 745         if (error)
 746                 return error;
 747         audit_file(file);
 748         error = chown_common(&file->f_path, user, group);
 749         mnt_drop_write_file(file);
 750         return error;
 751 }
 752
 753 int ksys_fchown(unsigned int fd, uid_t user, gid_t group)
 754 {
 755         struct fd f = fdget(fd);
 756         int error = -EBADF;
 757
 758         if (f.file) {
 759                 error = vfs_fchown(f.file, user, group);
 760                 fdput(f);
 761         }
 762         return error;
 763 }
 764
 765 SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group)
 766 {
 767         return ksys_fchown(fd, user, group);
 768 }
 769
 770 static int do_dentry_open(struct file *f,
 771                           struct inode *inode,
 772                           int (*open)(struct inode *, struct file *))
 773 {
 774         static const struct file_operations empty_fops = {};
 775         int error;
 776
 777         path_get(&f->f_path);
 778         f->f_inode = inode;
 779         f->f_mapping = inode->i_mapping;
 780         f->f_wb_err = filemap_sample_wb_err(f->f_mapping);
 781         f->f_sb_err = file_sample_sb_err(f);
 782
 783         if (unlikely(f->f_flags & O_PATH)) {
 784                 f->f_mode = FMODE_PATH | FMODE_OPENED;
 785                 f->f_op = &empty_fops;
 786                 return 0;
 787         }
 788
 789         if (f->f_mode & FMODE_WRITE && !special_file(inode->i_mode)) {
 790                 error = get_write_access(inode);
 791                 if (unlikely(error))
 792                         goto cleanup_file;
 793                 error = __mnt_want_write(f->f_path.mnt);
 794                 if (unlikely(error)) {
 795                         put_write_access(inode);
 796                         goto cleanup_file;
 797                 }
 798                 f->f_mode |= FMODE_WRITER;
 799         }
 800
 801         /* POSIX.1-2008/SUSv4 Section XSI 2.9.7 */
 802         if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode))
 803                 f->f_mode |= FMODE_ATOMIC_POS;
 804
 805         f->f_op = fops_get(inode->i_fop);
 806         if (WARN_ON(!f->f_op)) {
 807                 error = -ENODEV;
 808                 goto cleanup_all;
 809         }
 810
 811         error = security_file_open(f);
 812         if (error)
 813                 goto cleanup_all;
 814
 815         error = break_lease(locks_inode(f), f->f_flags);
 816         if (error)
 817                 goto cleanup_all;
 818
 819         /* normally all 3 are set; ->open() can clear them if needed */
 820         f->f_mode |= FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE;
 821         if (!open)
 822                 open = f->f_op->open;
 823         if (open) {
 824                 error = open(inode, f);
 825                 if (error)
 826                         goto cleanup_all;
 827         }
 828         f->f_mode |= FMODE_OPENED;
 829         if ((f->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
 830                 i_readcount_inc(inode);
 831         if ((f->f_mode & FMODE_READ) &&
 832              likely(f->f_op->read || f->f_op->read_iter))
 833                 f->f_mode |= FMODE_CAN_READ;
 834         if ((f->f_mode & FMODE_WRITE) &&
 835              likely(f->f_op->write || f->f_op->write_iter))
 836                 f->f_mode |= FMODE_CAN_WRITE;
 837
 838         f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
 839
 840         file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);
 841
 842         /* NB: we're sure to have correct a_ops only after f_op->open */
 843         if (f->f_flags & O_DIRECT) {
 844                 if (!f->f_mapping->a_ops || !f->f_mapping->a_ops->direct_IO)
 845                         return -EINVAL;
 846         }
 847
 848         /*
 849          * XXX: Huge page cache doesn't support writing yet. Drop all page
 850          * cache for this file before processing writes.
 851          */
 852         if (f->f_mode & FMODE_WRITE) {
 853                 /*
 854                  * Paired with smp_mb() in collapse_file() to ensure nr_thps
 855                  * is up to date and the update to i_writecount by
 856                  * get_write_access() is visible. Ensures subsequent insertion
 857                  * of THPs into the page cache will fail.
 858                  */
 859                 smp_mb();
 860                 if (filemap_nr_thps(inode->i_mapping)) {
 861                         struct address_space *mapping = inode->i_mapping;
 862
 863                         filemap_invalidate_lock(inode->i_mapping);
 864                         /*
 865                          * unmap_mapping_range just need to be called once
 866                          * here, because the private pages is not need to be
 867                          * unmapped mapping (e.g. data segment of dynamic
 868                          * shared libraries here).
 869                          */
 870                         unmap_mapping_range(mapping, 0, 0, 0);
 871                         truncate_inode_pages(mapping, 0);
 872                         filemap_invalidate_unlock(inode->i_mapping);
 873                 }
 874         }
 875
 876         return 0;
 877
 878 cleanup_all:
 879         if (WARN_ON_ONCE(error > 0))
 880                 error = -EINVAL;
 881         fops_put(f->f_op);
 882         if (f->f_mode & FMODE_WRITER) {
 883                 put_write_access(inode);
 884                 __mnt_drop_write(f->f_path.mnt);
 885         }
 886 cleanup_file:
 887         path_put(&f->f_path);
 888         f->f_path.mnt = NULL;
 889         f->f_path.dentry = NULL;
 890         f->f_inode = NULL;
 891         return error;
 892 }
 893
 894 /**
 895  * finish_open - finish opening a file
 896  * @file: file pointer
 897  * @dentry: pointer to dentry
 898  * @open: open callback
 899  * @opened: state of open
 900  *
 901  * This can be used to finish opening a file passed to i_op->atomic_open().
 902  *
 903  * If the open callback is set to NULL, then the standard f_op->open()
 904  * filesystem callback is substituted.
 905  *
 906  * NB: the dentry reference is _not_ consumed.  If, for example, the dentry is
 907  * the return value of d_splice_alias(), then the caller needs to perform dput()
 908  * on it after finish_open().
 909  *
 910  * Returns zero on success or -errno if the open failed.
 911  */
 912 int finish_open(struct file *file, struct dentry *dentry,
 913                 int (*open)(struct inode *, struct file *))
 914 {
 915         BUG_ON(file->f_mode & FMODE_OPENED); /* once it's opened, it's opened */
 916
 917         file->f_path.dentry = dentry;
 918         return do_dentry_open(file, d_backing_inode(dentry), open);
 919 }
 920 EXPORT_SYMBOL(finish_open);
 921
 922 /**
 923  * finish_no_open - finish ->atomic_open() without opening the file
 924  *
 925  * @file: file pointer
 926  * @dentry: dentry or NULL (as returned from ->lookup())
 927  *
 928  * This can be used to set the result of a successful lookup in ->atomic_open().
 929  *
 930  * NB: unlike finish_open() this function does consume the dentry reference and
 931  * the caller need not dput() it.
 932  *
 933  * Returns "0" which must be the return value of ->atomic_open() after having
 934  * called this function.
 935  */
 936 int finish_no_open(struct file *file, struct dentry *dentry)
 937 {
 938         file->f_path.dentry = dentry;
 939         return 0;
 940 }
 941 EXPORT_SYMBOL(finish_no_open);
 942
 943 char *file_path(struct file *filp, char *buf, int buflen)
 944 {
 945         return d_path(&filp->f_path, buf, buflen);
 946 }
 947 EXPORT_SYMBOL(file_path);
 948
 949 /**
 950  * vfs_open - open the file at the given path
 951  * @path: path to open
 952  * @file: newly allocated file with f_flag initialized
 953  * @cred: credentials to use
 954  */
 955 int vfs_open(const struct path *path, struct file *file)
 956 {
 957         file->f_path = *path;
 958         return do_dentry_open(file, d_backing_inode(path->dentry), NULL);
 959 }
 960
 961 struct file *dentry_open(const struct path *path, int flags,
 962                          const struct cred *cred)
 963 {
 964         int error;
 965         struct file *f;
 966
 967         validate_creds(cred);
 968
 969         /* We must always pass in a valid mount pointer. */
 970         BUG_ON(!path->mnt);
 971
 972         f = alloc_empty_file(flags, cred);
 973         if (!IS_ERR(f)) {
 974                 error = vfs_open(path, f);
 975                 if (error) {
 976                         fput(f);
 977                         f = ERR_PTR(error);
 978                 }
 979         }
 980         return f;
 981 }
 982 EXPORT_SYMBOL(dentry_open);
 983
 984 struct file *open_with_fake_path(const struct path *path, int flags,
 985                                 struct inode *inode, const struct cred *cred)
 986 {
 987         struct file *f = alloc_empty_file_noaccount(flags, cred);
 988         if (!IS_ERR(f)) {
 989                 int error;
 990
 991                 f->f_path = *path;
 992                 error = do_dentry_open(f, inode, NULL);
 993                 if (error) {
 994                         fput(f);
 995                         f = ERR_PTR(error);
 996                 }
 997         }
 998         return f;
 999 }
1000 EXPORT_SYMBOL(open_with_fake_path);
1001
1002 #define WILL_CREATE(flags)      (flags & (O_CREAT | __O_TMPFILE))
1003 #define O_PATH_FLAGS            (O_DIRECTORY | O_NOFOLLOW | O_PATH | O_CLOEXEC)
1004
1005 inline struct open_how build_open_how(int flags, umode_t mode)
1006 {
1007         struct open_how how = {
1008                 .flags = flags & VALID_OPEN_FLAGS,
1009                 .mode = mode & S_IALLUGO,
1010         };
1011
1012         /* O_PATH beats everything else. */
1013         if (how.flags & O_PATH)
1014                 how.flags &= O_PATH_FLAGS;
1015         /* Modes should only be set for create-like flags. */
1016         if (!WILL_CREATE(how.flags))
1017                 how.mode = 0;
1018         return how;
1019 }
1020
1021 inline int build_open_flags(const struct open_how *how, struct open_flags *op)
1022 {
1023         u64 flags = how->flags;
1024         u64 strip = FMODE_NONOTIFY | O_CLOEXEC;
1025         int lookup_flags = 0;
1026         int acc_mode = ACC_MODE(flags);
1027
1028         BUILD_BUG_ON_MSG(upper_32_bits(VALID_OPEN_FLAGS),
1029                          "struct open_flags doesn't yet handle flags > 32 bits");
1030
1031         /*
1032          * Strip flags that either shouldn't be set by userspace like
1033          * FMODE_NONOTIFY or that aren't relevant in determining struct
1034          * open_flags like O_CLOEXEC.
1035          */
1036         flags &= ~strip;
1037
1038         /*
1039          * Older syscalls implicitly clear all of the invalid flags or argument
1040          * values before calling build_open_flags(), but openat2(2) checks all
1041          * of its arguments.
1042          */
1043         if (flags & ~VALID_OPEN_FLAGS)
1044                 return -EINVAL;
1045         if (how->resolve & ~VALID_RESOLVE_FLAGS)
1046                 return -EINVAL;
1047
1048         /* Scoping flags are mutually exclusive. */
1049         if ((how->resolve & RESOLVE_BENEATH) && (how->resolve & RESOLVE_IN_ROOT))
1050                 return -EINVAL;
1051
1052         /* Deal with the mode. */
1053         if (WILL_CREATE(flags)) {
1054                 if (how->mode & ~S_IALLUGO)
1055                         return -EINVAL;
1056                 op->mode = how->mode | S_IFREG;
1057         } else {
1058                 if (how->mode != 0)
1059                         return -EINVAL;
1060                 op->mode = 0;
1061         }
1062
1063         /*
1064          * In order to ensure programs get explicit errors when trying to use
1065          * O_TMPFILE on old kernels, O_TMPFILE is implemented such that it
1066          * looks like (O_DIRECTORY|O_RDWR & ~O_CREAT) to old kernels. But we
1067          * have to require userspace to explicitly set it.
1068          */
1069         if (flags & __O_TMPFILE) {
1070                 if ((flags & O_TMPFILE_MASK) != O_TMPFILE)
1071                         return -EINVAL;
1072                 if (!(acc_mode & MAY_WRITE))
1073                         return -EINVAL;
1074         }
1075         if (flags & O_PATH) {
1076                 /* O_PATH only permits certain other flags to be set. */
1077                 if (flags & ~O_PATH_FLAGS)
1078                         return -EINVAL;
1079                 acc_mode = 0;
1080         }
1081
1082         /*
1083          * O_SYNC is implemented as __O_SYNC|O_DSYNC.  As many places only
1084          * check for O_DSYNC if the need any syncing at all we enforce it's
1085          * always set instead of having to deal with possibly weird behaviour
1086          * for malicious applications setting only __O_SYNC.
1087          */
1088         if (flags & __O_SYNC)
1089                 flags |= O_DSYNC;
1090
1091         op->open_flag = flags;
1092
1093         /* O_TRUNC implies we need access checks for write permissions */
1094         if (flags & O_TRUNC)
1095                 acc_mode |= MAY_WRITE;
1096
1097         /* Allow the LSM permission hook to distinguish append
1098            access from general write access. */
1099         if (flags & O_APPEND)
1100                 acc_mode |= MAY_APPEND;
1101
1102         op->acc_mode = acc_mode;
1103
1104         op->intent = flags & O_PATH ? 0 : LOOKUP_OPEN;
1105
1106         if (flags & O_CREAT) {
1107                 op->intent |= LOOKUP_CREATE;
1108                 if (flags & O_EXCL) {
1109                         op->intent |= LOOKUP_EXCL;
1110                         flags |= O_NOFOLLOW;
1111                 }
1112         }
1113
1114         if (flags & O_DIRECTORY)
1115                 lookup_flags |= LOOKUP_DIRECTORY;
1116         if (!(flags & O_NOFOLLOW))
1117                 lookup_flags |= LOOKUP_FOLLOW;
1118
1119         if (how->resolve & RESOLVE_NO_XDEV)
1120                 lookup_flags |= LOOKUP_NO_XDEV;
1121         if (how->resolve & RESOLVE_NO_MAGICLINKS)
1122                 lookup_flags |= LOOKUP_NO_MAGICLINKS;
1123         if (how->resolve & RESOLVE_NO_SYMLINKS)
1124                 lookup_flags |= LOOKUP_NO_SYMLINKS;
1125         if (how->resolve & RESOLVE_BENEATH)
1126                 lookup_flags |= LOOKUP_BENEATH;
1127         if (how->resolve & RESOLVE_IN_ROOT)
1128                 lookup_flags |= LOOKUP_IN_ROOT;
1129         if (how->resolve & RESOLVE_CACHED) {
1130                 /* Don't bother even trying for create/truncate/tmpfile open */
1131                 if (flags & (O_TRUNC | O_CREAT | O_TMPFILE))
1132                         return -EAGAIN;
1133                 lookup_flags |= LOOKUP_CACHED;
1134         }
1135
1136         op->lookup_flags = lookup_flags;
1137         return 0;
1138 }
1139
1140 /**
1141  * file_open_name - open file and return file pointer
1142  *
1143  * @name:       struct filename containing path to open
1144  * @flags:      open flags as per the open(2) second argument
1145  * @mode:       mode for the new file if O_CREAT is set, else ignored
1146  *
1147  * This is the helper to open a file from kernelspace if you really
1148  * have to.  But in generally you should not do this, so please move
1149  * along, nothing to see here..
1150  */
1151 struct file *file_open_name(struct filename *name, int flags, umode_t mode)
1152 {
1153         struct open_flags op;
1154         struct open_how how = build_open_how(flags, mode);
1155         int err = build_open_flags(&how, &op);
1156         if (err)
1157                 return ERR_PTR(err);
1158         return do_filp_open(AT_FDCWD, name, &op);
1159 }
1160
1161 /**
1162  * filp_open - open file and return file pointer
1163  *
1164  * @filename:   path to open
1165  * @flags:      open flags as per the open(2) second argument
1166  * @mode:       mode for the new file if O_CREAT is set, else ignored
1167  *
1168  * This is the helper to open a file from kernelspace if you really
1169  * have to.  But in generally you should not do this, so please move
1170  * along, nothing to see here..
1171  */
1172 struct file *filp_open(const char *filename, int flags, umode_t mode)
1173 {
1174         struct filename *name = getname_kernel(filename);
1175         struct file *file = ERR_CAST(name);
1176
1177         if (!IS_ERR(name)) {
1178                 file = file_open_name(name, flags, mode);
1179                 putname(name);
1180         }
1181         return file;
1182 }
1183 EXPORT_SYMBOL(filp_open);
1184
1185 struct file *file_open_root(const struct path *root,
1186                             const char *filename, int flags, umode_t mode)
1187 {
1188         struct open_flags op;
1189         struct open_how how = build_open_how(flags, mode);
1190         int err = build_open_flags(&how, &op);
1191         if (err)
1192                 return ERR_PTR(err);
1193         return do_file_open_root(root, filename, &op);
1194 }
1195 EXPORT_SYMBOL(file_open_root);
1196
1197 static long do_sys_openat2(int dfd, const char __user *filename,
1198                            struct open_how *how)
1199 {
1200         struct open_flags op;
1201         int fd = build_open_flags(how, &op);
1202         struct filename *tmp;
1203
1204         if (fd)
1205                 return fd;
1206
1207         tmp = getname(filename);
1208         if (IS_ERR(tmp))
1209                 return PTR_ERR(tmp);
1210
1211         fd = get_unused_fd_flags(how->flags);
1212         if (fd >= 0) {
1213                 struct file *f = do_filp_open(dfd, tmp, &op);
1214                 if (IS_ERR(f)) {
1215                         put_unused_fd(fd);
1216                         fd = PTR_ERR(f);
1217                 } else {
1218                         fsnotify_open(f);
1219                         fd_install(fd, f);
1220                 }
1221         }
1222         putname(tmp);
1223         return fd;
1224 }
1225
1226 long do_sys_open(int dfd, const char __user *filename, int flags, umode_t mode)
1227 {
1228         struct open_how how = build_open_how(flags, mode);
1229         return do_sys_openat2(dfd, filename, &how);
1230 }
1231
1232
1233 SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)
1234 {
1235         if (force_o_largefile())
1236                 flags |= O_LARGEFILE;
1237         return do_sys_open(AT_FDCWD, filename, flags, mode);
1238 }
1239
1240 SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags,
1241                 umode_t, mode)
1242 {
1243         if (force_o_largefile())
1244                 flags |= O_LARGEFILE;
1245         return do_sys_open(dfd, filename, flags, mode);
1246 }
1247
1248 SYSCALL_DEFINE4(openat2, int, dfd, const char __user *, filename,
1249                 struct open_how __user *, how, size_t, usize)
1250 {
1251         int err;
1252         struct open_how tmp;
1253
1254         BUILD_BUG_ON(sizeof(struct open_how) < OPEN_HOW_SIZE_VER0);
1255         BUILD_BUG_ON(sizeof(struct open_how) != OPEN_HOW_SIZE_LATEST);
1256
1257         if (unlikely(usize < OPEN_HOW_SIZE_VER0))
1258                 return -EINVAL;
1259
1260         err = copy_struct_from_user(&tmp, sizeof(tmp), how, usize);
1261         if (err)
1262                 return err;
1263
1264         audit_openat2_how(&tmp);
1265
1266         /* O_LARGEFILE is only allowed for non-O_PATH. */
1267         if (!(tmp.flags & O_PATH) && force_o_largefile())
1268                 tmp.flags |= O_LARGEFILE;
1269
1270         return do_sys_openat2(dfd, filename, &tmp);
1271 }
1272
1273 #ifdef CONFIG_COMPAT
1274 /*
1275  * Exactly like sys_open(), except that it doesn't set the
1276  * O_LARGEFILE flag.
1277  */
1278 COMPAT_SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)
1279 {
1280         return do_sys_open(AT_FDCWD, filename, flags, mode);
1281 }
1282
1283 /*
1284  * Exactly like sys_openat(), except that it doesn't set the
1285  * O_LARGEFILE flag.
1286  */
1287 COMPAT_SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags, umode_t, mode)
1288 {
1289         return do_sys_open(dfd, filename, flags, mode);
1290 }
1291 #endif
1292
1293 #ifndef __alpha__
1294
1295 /*
1296  * For backward compatibility?  Maybe this should be moved
1297  * into arch/i386 instead?
1298  */
1299 SYSCALL_DEFINE2(creat, const char __user *, pathname, umode_t, mode)
1300 {
1301         int flags = O_CREAT | O_WRONLY | O_TRUNC;
1302
1303         if (force_o_largefile())
1304                 flags |= O_LARGEFILE;
1305         return do_sys_open(AT_FDCWD, pathname, flags, mode);
1306 }
1307 #endif
1308
1309 /*
1310  * "id" is the POSIX thread ID. We use the
1311  * files pointer for this..
1312  */
1313 int filp_close(struct file *filp, fl_owner_t id)
1314 {
1315         int retval = 0;
1316
1317         if (!file_count(filp)) {
1318                 printk(KERN_ERR "VFS: Close: file count is 0\n");
1319                 return 0;
1320         }
1321
1322         if (filp->f_op->flush)
1323                 retval = filp->f_op->flush(filp, id);
1324
1325         if (likely(!(filp->f_mode & FMODE_PATH))) {
1326                 dnotify_flush(filp, id);
1327                 locks_remove_posix(filp, id);
1328         }
1329         fput(filp);
1330         return retval;
1331 }
1332
1333 EXPORT_SYMBOL(filp_close);
1334
1335 /*
1336  * Careful here! We test whether the file pointer is NULL before
1337  * releasing the fd. This ensures that one clone task can't release
1338  * an fd while another clone is opening it.
1339  */
1340 SYSCALL_DEFINE1(close, unsigned int, fd)
1341 {
1342         int retval = close_fd(fd);
1343
1344         /* can't restart close syscall because file table entry was cleared */
1345         if (unlikely(retval == -ERESTARTSYS ||
1346                      retval == -ERESTARTNOINTR ||
1347                      retval == -ERESTARTNOHAND ||
1348                      retval == -ERESTART_RESTARTBLOCK))
1349                 retval = -EINTR;
1350
1351         return retval;
1352 }
1353
1354 /**
1355  * close_range() - Close all file descriptors in a given range.
1356  *
1357  * @fd:     starting file descriptor to close
1358  * @max_fd: last file descriptor to close
1359  * @flags:  reserved for future extensions
1360  *
1361  * This closes a range of file descriptors. All file descriptors
1362  * from @fd up to and including @max_fd are closed.
1363  * Currently, errors to close a given file descriptor are ignored.
1364  */
1365 SYSCALL_DEFINE3(close_range, unsigned int, fd, unsigned int, max_fd,
1366                 unsigned int, flags)
1367 {
1368         return __close_range(fd, max_fd, flags);
1369 }
1370
1371 /*
1372  * This routine simulates a hangup on the tty, to arrange that users
1373  * are given clean terminals at login time.
1374  */
1375 SYSCALL_DEFINE0(vhangup)
1376 {
1377         if (capable(CAP_SYS_TTY_CONFIG)) {
1378                 tty_vhangup_self();
1379                 return 0;
1380         }
1381         return -EPERM;
1382 }
1383
1384 /*
1385  * Called when an inode is about to be open.
1386  * We use this to disallow opening large files on 32bit systems if
1387  * the caller didn't specify O_LARGEFILE.  On 64bit systems we force
1388  * on this flag in sys_open.
1389  */
1390 int generic_file_open(struct inode * inode, struct file * filp)
1391 {
1392         if (!(filp->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS)
1393                 return -EOVERFLOW;
1394         return 0;
1395 }
1396
1397 EXPORT_SYMBOL(generic_file_open);
1398
1399 /*
1400  * This is used by subsystems that don't want seekable
1401  * file descriptors. The function is not supposed to ever fail, the only
1402  * reason it returns an 'int' and not 'void' is so that it can be plugged
1403  * directly into file_operations structure.
1404  */
1405 int nonseekable_open(struct inode *inode, struct file *filp)
1406 {
1407         filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);
1408         return 0;
1409 }
1410
1411 EXPORT_SYMBOL(nonseekable_open);
1412
1413 /*
1414  * stream_open is used by subsystems that want stream-like file descriptors.
1415  * Such file descriptors are not seekable and don't have notion of position
1416  * (file.f_pos is always 0 and ppos passed to .read()/.write() is always NULL).
1417  * Contrary to file descriptors of other regular files, .read() and .write()
1418  * can run simultaneously.
1419  *
1420  * stream_open never fails and is marked to return int so that it could be
1421  * directly used as file_operations.open .
1422  */
1423 int stream_open(struct inode *inode, struct file *filp)
1424 {
1425         filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE | FMODE_ATOMIC_POS);
1426         filp->f_mode |= FMODE_STREAM;
1427         return 0;
1428 }
1429
1430 EXPORT_SYMBOL(stream_open);