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