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/smp_lock.h> 11 #include <linux/quotaops.h> 12 #include <linux/fsnotify.h> 13 #include <linux/module.h> 14 #include <linux/slab.h> 15 #include <linux/tty.h> 16 #include <linux/namei.h> 17 #include <linux/backing-dev.h> 18 #include <linux/capability.h> 19 #include <linux/security.h> 20 #include <linux/mount.h> 21 #include <linux/vfs.h> 22 #include <linux/fcntl.h> 23 #include <asm/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 31 int vfs_statfs(struct dentry *dentry, struct kstatfs *buf) 32 { 33 int retval = -ENODEV; 34 35 if (dentry) { 36 retval = -ENOSYS; 37 if (dentry->d_sb->s_op->statfs) { 38 memset(buf, 0, sizeof(*buf)); 39 retval = security_sb_statfs(dentry); 40 if (retval) 41 return retval; 42 retval = dentry->d_sb->s_op->statfs(dentry, buf); 43 if (retval == 0 && buf->f_frsize == 0) 44 buf->f_frsize = buf->f_bsize; 45 } 46 } 47 return retval; 48 } 49 50 EXPORT_SYMBOL(vfs_statfs); 51 52 static int vfs_statfs_native(struct dentry *dentry, struct statfs *buf) 53 { 54 struct kstatfs st; 55 int retval; 56 57 retval = vfs_statfs(dentry, &st); 58 if (retval) 59 return retval; 60 61 if (sizeof(*buf) == sizeof(st)) 62 memcpy(buf, &st, sizeof(st)); 63 else { 64 if (sizeof buf->f_blocks == 4) { 65 if ((st.f_blocks | st.f_bfree | st.f_bavail) & 66 0xffffffff00000000ULL) 67 return -EOVERFLOW; 68 /* 69 * f_files and f_ffree may be -1; it's okay to stuff 70 * that into 32 bits 71 */ 72 if (st.f_files != -1 && 73 (st.f_files & 0xffffffff00000000ULL)) 74 return -EOVERFLOW; 75 if (st.f_ffree != -1 && 76 (st.f_ffree & 0xffffffff00000000ULL)) 77 return -EOVERFLOW; 78 } 79 80 buf->f_type = st.f_type; 81 buf->f_bsize = st.f_bsize; 82 buf->f_blocks = st.f_blocks; 83 buf->f_bfree = st.f_bfree; 84 buf->f_bavail = st.f_bavail; 85 buf->f_files = st.f_files; 86 buf->f_ffree = st.f_ffree; 87 buf->f_fsid = st.f_fsid; 88 buf->f_namelen = st.f_namelen; 89 buf->f_frsize = st.f_frsize; 90 memset(buf->f_spare, 0, sizeof(buf->f_spare)); 91 } 92 return 0; 93 } 94 95 static int vfs_statfs64(struct dentry *dentry, struct statfs64 *buf) 96 { 97 struct kstatfs st; 98 int retval; 99 100 retval = vfs_statfs(dentry, &st); 101 if (retval) 102 return retval; 103 104 if (sizeof(*buf) == sizeof(st)) 105 memcpy(buf, &st, sizeof(st)); 106 else { 107 buf->f_type = st.f_type; 108 buf->f_bsize = st.f_bsize; 109 buf->f_blocks = st.f_blocks; 110 buf->f_bfree = st.f_bfree; 111 buf->f_bavail = st.f_bavail; 112 buf->f_files = st.f_files; 113 buf->f_ffree = st.f_ffree; 114 buf->f_fsid = st.f_fsid; 115 buf->f_namelen = st.f_namelen; 116 buf->f_frsize = st.f_frsize; 117 memset(buf->f_spare, 0, sizeof(buf->f_spare)); 118 } 119 return 0; 120 } 121 122 asmlinkage long sys_statfs(const char __user * path, struct statfs __user * buf) 123 { 124 struct nameidata nd; 125 int error; 126 127 error = user_path_walk(path, &nd); 128 if (!error) { 129 struct statfs tmp; 130 error = vfs_statfs_native(nd.dentry, &tmp); 131 if (!error && copy_to_user(buf, &tmp, sizeof(tmp))) 132 error = -EFAULT; 133 path_release(&nd); 134 } 135 return error; 136 } 137 138 139 asmlinkage long sys_statfs64(const char __user *path, size_t sz, struct statfs64 __user *buf) 140 { 141 struct nameidata nd; 142 long error; 143 144 if (sz != sizeof(*buf)) 145 return -EINVAL; 146 error = user_path_walk(path, &nd); 147 if (!error) { 148 struct statfs64 tmp; 149 error = vfs_statfs64(nd.dentry, &tmp); 150 if (!error && copy_to_user(buf, &tmp, sizeof(tmp))) 151 error = -EFAULT; 152 path_release(&nd); 153 } 154 return error; 155 } 156 157 158 asmlinkage long sys_fstatfs(unsigned int fd, struct statfs __user * buf) 159 { 160 struct file * file; 161 struct statfs tmp; 162 int error; 163 164 error = -EBADF; 165 file = fget(fd); 166 if (!file) 167 goto out; 168 error = vfs_statfs_native(file->f_path.dentry, &tmp); 169 if (!error && copy_to_user(buf, &tmp, sizeof(tmp))) 170 error = -EFAULT; 171 fput(file); 172 out: 173 return error; 174 } 175 176 asmlinkage long sys_fstatfs64(unsigned int fd, size_t sz, struct statfs64 __user *buf) 177 { 178 struct file * file; 179 struct statfs64 tmp; 180 int error; 181 182 if (sz != sizeof(*buf)) 183 return -EINVAL; 184 185 error = -EBADF; 186 file = fget(fd); 187 if (!file) 188 goto out; 189 error = vfs_statfs64(file->f_path.dentry, &tmp); 190 if (!error && copy_to_user(buf, &tmp, sizeof(tmp))) 191 error = -EFAULT; 192 fput(file); 193 out: 194 return error; 195 } 196 197 int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs, 198 struct file *filp) 199 { 200 int err; 201 struct iattr newattrs; 202 203 /* Not pretty: "inode->i_size" shouldn't really be signed. But it is. */ 204 if (length < 0) 205 return -EINVAL; 206 207 newattrs.ia_size = length; 208 newattrs.ia_valid = ATTR_SIZE | time_attrs; 209 if (filp) { 210 newattrs.ia_file = filp; 211 newattrs.ia_valid |= ATTR_FILE; 212 } 213 214 mutex_lock(&dentry->d_inode->i_mutex); 215 err = notify_change(dentry, &newattrs); 216 mutex_unlock(&dentry->d_inode->i_mutex); 217 return err; 218 } 219 220 static long do_sys_truncate(const char __user * path, loff_t length) 221 { 222 struct nameidata nd; 223 struct inode * inode; 224 int error; 225 226 error = -EINVAL; 227 if (length < 0) /* sorry, but loff_t says... */ 228 goto out; 229 230 error = user_path_walk(path, &nd); 231 if (error) 232 goto out; 233 inode = nd.dentry->d_inode; 234 235 /* For directories it's -EISDIR, for other non-regulars - -EINVAL */ 236 error = -EISDIR; 237 if (S_ISDIR(inode->i_mode)) 238 goto dput_and_out; 239 240 error = -EINVAL; 241 if (!S_ISREG(inode->i_mode)) 242 goto dput_and_out; 243 244 error = vfs_permission(&nd, MAY_WRITE); 245 if (error) 246 goto dput_and_out; 247 248 error = -EROFS; 249 if (IS_RDONLY(inode)) 250 goto dput_and_out; 251 252 error = -EPERM; 253 if (IS_IMMUTABLE(inode) || IS_APPEND(inode)) 254 goto dput_and_out; 255 256 /* 257 * Make sure that there are no leases. 258 */ 259 error = break_lease(inode, FMODE_WRITE); 260 if (error) 261 goto dput_and_out; 262 263 error = get_write_access(inode); 264 if (error) 265 goto dput_and_out; 266 267 error = locks_verify_truncate(inode, NULL, length); 268 if (!error) { 269 DQUOT_INIT(inode); 270 error = do_truncate(nd.dentry, length, 0, NULL); 271 } 272 put_write_access(inode); 273 274 dput_and_out: 275 path_release(&nd); 276 out: 277 return error; 278 } 279 280 asmlinkage long sys_truncate(const char __user * path, unsigned long length) 281 { 282 /* on 32-bit boxen it will cut the range 2^31--2^32-1 off */ 283 return do_sys_truncate(path, (long)length); 284 } 285 286 static long do_sys_ftruncate(unsigned int fd, loff_t length, int small) 287 { 288 struct inode * inode; 289 struct dentry *dentry; 290 struct file * file; 291 int error; 292 293 error = -EINVAL; 294 if (length < 0) 295 goto out; 296 error = -EBADF; 297 file = fget(fd); 298 if (!file) 299 goto out; 300 301 /* explicitly opened as large or we are on 64-bit box */ 302 if (file->f_flags & O_LARGEFILE) 303 small = 0; 304 305 dentry = file->f_path.dentry; 306 inode = dentry->d_inode; 307 error = -EINVAL; 308 if (!S_ISREG(inode->i_mode) || !(file->f_mode & FMODE_WRITE)) 309 goto out_putf; 310 311 error = -EINVAL; 312 /* Cannot ftruncate over 2^31 bytes without large file support */ 313 if (small && length > MAX_NON_LFS) 314 goto out_putf; 315 316 error = -EPERM; 317 if (IS_APPEND(inode)) 318 goto out_putf; 319 320 error = locks_verify_truncate(inode, file, length); 321 if (!error) 322 error = do_truncate(dentry, length, ATTR_MTIME|ATTR_CTIME, file); 323 out_putf: 324 fput(file); 325 out: 326 return error; 327 } 328 329 asmlinkage long sys_ftruncate(unsigned int fd, unsigned long length) 330 { 331 long ret = do_sys_ftruncate(fd, length, 1); 332 /* avoid REGPARM breakage on x86: */ 333 prevent_tail_call(ret); 334 return ret; 335 } 336 337 /* LFS versions of truncate are only needed on 32 bit machines */ 338 #if BITS_PER_LONG == 32 339 asmlinkage long sys_truncate64(const char __user * path, loff_t length) 340 { 341 return do_sys_truncate(path, length); 342 } 343 344 asmlinkage long sys_ftruncate64(unsigned int fd, loff_t length) 345 { 346 long ret = do_sys_ftruncate(fd, length, 0); 347 /* avoid REGPARM breakage on x86: */ 348 prevent_tail_call(ret); 349 return ret; 350 } 351 #endif 352 353 /* 354 * access() needs to use the real uid/gid, not the effective uid/gid. 355 * We do this by temporarily clearing all FS-related capabilities and 356 * switching the fsuid/fsgid around to the real ones. 357 */ 358 asmlinkage long sys_faccessat(int dfd, const char __user *filename, int mode) 359 { 360 struct nameidata nd; 361 int old_fsuid, old_fsgid; 362 kernel_cap_t old_cap; 363 int res; 364 365 if (mode & ~S_IRWXO) /* where's F_OK, X_OK, W_OK, R_OK? */ 366 return -EINVAL; 367 368 old_fsuid = current->fsuid; 369 old_fsgid = current->fsgid; 370 old_cap = current->cap_effective; 371 372 current->fsuid = current->uid; 373 current->fsgid = current->gid; 374 375 /* 376 * Clear the capabilities if we switch to a non-root user 377 * 378 * FIXME: There is a race here against sys_capset. The 379 * capabilities can change yet we will restore the old 380 * value below. We should hold task_capabilities_lock, 381 * but we cannot because user_path_walk can sleep. 382 */ 383 if (current->uid) 384 cap_clear(current->cap_effective); 385 else 386 current->cap_effective = current->cap_permitted; 387 388 res = __user_walk_fd(dfd, filename, LOOKUP_FOLLOW|LOOKUP_ACCESS, &nd); 389 if (res) 390 goto out; 391 392 res = vfs_permission(&nd, mode); 393 /* SuS v2 requires we report a read only fs too */ 394 if(res || !(mode & S_IWOTH) || 395 special_file(nd.dentry->d_inode->i_mode)) 396 goto out_path_release; 397 398 if(IS_RDONLY(nd.dentry->d_inode)) 399 res = -EROFS; 400 401 out_path_release: 402 path_release(&nd); 403 out: 404 current->fsuid = old_fsuid; 405 current->fsgid = old_fsgid; 406 current->cap_effective = old_cap; 407 408 return res; 409 } 410 411 asmlinkage long sys_access(const char __user *filename, int mode) 412 { 413 return sys_faccessat(AT_FDCWD, filename, mode); 414 } 415 416 asmlinkage long sys_chdir(const char __user * filename) 417 { 418 struct nameidata nd; 419 int error; 420 421 error = __user_walk(filename, 422 LOOKUP_FOLLOW|LOOKUP_DIRECTORY|LOOKUP_CHDIR, &nd); 423 if (error) 424 goto out; 425 426 error = vfs_permission(&nd, MAY_EXEC); 427 if (error) 428 goto dput_and_out; 429 430 set_fs_pwd(current->fs, nd.mnt, nd.dentry); 431 432 dput_and_out: 433 path_release(&nd); 434 out: 435 return error; 436 } 437 438 asmlinkage long sys_fchdir(unsigned int fd) 439 { 440 struct file *file; 441 struct dentry *dentry; 442 struct inode *inode; 443 struct vfsmount *mnt; 444 int error; 445 446 error = -EBADF; 447 file = fget(fd); 448 if (!file) 449 goto out; 450 451 dentry = file->f_path.dentry; 452 mnt = file->f_path.mnt; 453 inode = dentry->d_inode; 454 455 error = -ENOTDIR; 456 if (!S_ISDIR(inode->i_mode)) 457 goto out_putf; 458 459 error = file_permission(file, MAY_EXEC); 460 if (!error) 461 set_fs_pwd(current->fs, mnt, dentry); 462 out_putf: 463 fput(file); 464 out: 465 return error; 466 } 467 468 asmlinkage long sys_chroot(const char __user * filename) 469 { 470 struct nameidata nd; 471 int error; 472 473 error = __user_walk(filename, LOOKUP_FOLLOW | LOOKUP_DIRECTORY | LOOKUP_NOALT, &nd); 474 if (error) 475 goto out; 476 477 error = vfs_permission(&nd, MAY_EXEC); 478 if (error) 479 goto dput_and_out; 480 481 error = -EPERM; 482 if (!capable(CAP_SYS_CHROOT)) 483 goto dput_and_out; 484 485 set_fs_root(current->fs, nd.mnt, nd.dentry); 486 set_fs_altroot(); 487 error = 0; 488 dput_and_out: 489 path_release(&nd); 490 out: 491 return error; 492 } 493 494 asmlinkage long sys_fchmod(unsigned int fd, mode_t mode) 495 { 496 struct inode * inode; 497 struct dentry * dentry; 498 struct file * file; 499 int err = -EBADF; 500 struct iattr newattrs; 501 502 file = fget(fd); 503 if (!file) 504 goto out; 505 506 dentry = file->f_path.dentry; 507 inode = dentry->d_inode; 508 509 audit_inode(NULL, inode); 510 511 err = -EROFS; 512 if (IS_RDONLY(inode)) 513 goto out_putf; 514 err = -EPERM; 515 if (IS_IMMUTABLE(inode) || IS_APPEND(inode)) 516 goto out_putf; 517 mutex_lock(&inode->i_mutex); 518 if (mode == (mode_t) -1) 519 mode = inode->i_mode; 520 newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO); 521 newattrs.ia_valid = ATTR_MODE | ATTR_CTIME; 522 err = notify_change(dentry, &newattrs); 523 mutex_unlock(&inode->i_mutex); 524 525 out_putf: 526 fput(file); 527 out: 528 return err; 529 } 530 531 asmlinkage long sys_fchmodat(int dfd, const char __user *filename, 532 mode_t mode) 533 { 534 struct nameidata nd; 535 struct inode * inode; 536 int error; 537 struct iattr newattrs; 538 539 error = __user_walk_fd(dfd, filename, LOOKUP_FOLLOW, &nd); 540 if (error) 541 goto out; 542 inode = nd.dentry->d_inode; 543 544 error = -EROFS; 545 if (IS_RDONLY(inode)) 546 goto dput_and_out; 547 548 error = -EPERM; 549 if (IS_IMMUTABLE(inode) || IS_APPEND(inode)) 550 goto dput_and_out; 551 552 mutex_lock(&inode->i_mutex); 553 if (mode == (mode_t) -1) 554 mode = inode->i_mode; 555 newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO); 556 newattrs.ia_valid = ATTR_MODE | ATTR_CTIME; 557 error = notify_change(nd.dentry, &newattrs); 558 mutex_unlock(&inode->i_mutex); 559 560 dput_and_out: 561 path_release(&nd); 562 out: 563 return error; 564 } 565 566 asmlinkage long sys_chmod(const char __user *filename, mode_t mode) 567 { 568 return sys_fchmodat(AT_FDCWD, filename, mode); 569 } 570 571 static int chown_common(struct dentry * dentry, uid_t user, gid_t group) 572 { 573 struct inode * inode; 574 int error; 575 struct iattr newattrs; 576 577 error = -ENOENT; 578 if (!(inode = dentry->d_inode)) { 579 printk(KERN_ERR "chown_common: NULL inode\n"); 580 goto out; 581 } 582 error = -EROFS; 583 if (IS_RDONLY(inode)) 584 goto out; 585 error = -EPERM; 586 if (IS_IMMUTABLE(inode) || IS_APPEND(inode)) 587 goto out; 588 newattrs.ia_valid = ATTR_CTIME; 589 if (user != (uid_t) -1) { 590 newattrs.ia_valid |= ATTR_UID; 591 newattrs.ia_uid = user; 592 } 593 if (group != (gid_t) -1) { 594 newattrs.ia_valid |= ATTR_GID; 595 newattrs.ia_gid = group; 596 } 597 if (!S_ISDIR(inode->i_mode)) 598 newattrs.ia_valid |= ATTR_KILL_SUID|ATTR_KILL_SGID; 599 mutex_lock(&inode->i_mutex); 600 error = notify_change(dentry, &newattrs); 601 mutex_unlock(&inode->i_mutex); 602 out: 603 return error; 604 } 605 606 asmlinkage long sys_chown(const char __user * filename, uid_t user, gid_t group) 607 { 608 struct nameidata nd; 609 int error; 610 611 error = user_path_walk(filename, &nd); 612 if (error) 613 goto out; 614 error = chown_common(nd.dentry, user, group); 615 path_release(&nd); 616 out: 617 return error; 618 } 619 620 asmlinkage long sys_fchownat(int dfd, const char __user *filename, uid_t user, 621 gid_t group, int flag) 622 { 623 struct nameidata nd; 624 int error = -EINVAL; 625 int follow; 626 627 if ((flag & ~AT_SYMLINK_NOFOLLOW) != 0) 628 goto out; 629 630 follow = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW; 631 error = __user_walk_fd(dfd, filename, follow, &nd); 632 if (error) 633 goto out; 634 error = chown_common(nd.dentry, user, group); 635 path_release(&nd); 636 out: 637 return error; 638 } 639 640 asmlinkage long sys_lchown(const char __user * filename, uid_t user, gid_t group) 641 { 642 struct nameidata nd; 643 int error; 644 645 error = user_path_walk_link(filename, &nd); 646 if (error) 647 goto out; 648 error = chown_common(nd.dentry, user, group); 649 path_release(&nd); 650 out: 651 return error; 652 } 653 654 655 asmlinkage long sys_fchown(unsigned int fd, uid_t user, gid_t group) 656 { 657 struct file * file; 658 int error = -EBADF; 659 struct dentry * dentry; 660 661 file = fget(fd); 662 if (!file) 663 goto out; 664 665 dentry = file->f_path.dentry; 666 audit_inode(NULL, dentry->d_inode); 667 error = chown_common(dentry, user, group); 668 fput(file); 669 out: 670 return error; 671 } 672 673 static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt, 674 int flags, struct file *f, 675 int (*open)(struct inode *, struct file *)) 676 { 677 struct inode *inode; 678 int error; 679 680 f->f_flags = flags; 681 f->f_mode = ((flags+1) & O_ACCMODE) | FMODE_LSEEK | 682 FMODE_PREAD | FMODE_PWRITE; 683 inode = dentry->d_inode; 684 if (f->f_mode & FMODE_WRITE) { 685 error = get_write_access(inode); 686 if (error) 687 goto cleanup_file; 688 } 689 690 f->f_mapping = inode->i_mapping; 691 f->f_path.dentry = dentry; 692 f->f_path.mnt = mnt; 693 f->f_pos = 0; 694 f->f_op = fops_get(inode->i_fop); 695 file_move(f, &inode->i_sb->s_files); 696 697 if (!open && f->f_op) 698 open = f->f_op->open; 699 if (open) { 700 error = open(inode, f); 701 if (error) 702 goto cleanup_all; 703 } 704 705 f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC); 706 707 file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping); 708 709 /* NB: we're sure to have correct a_ops only after f_op->open */ 710 if (f->f_flags & O_DIRECT) { 711 if (!f->f_mapping->a_ops || 712 ((!f->f_mapping->a_ops->direct_IO) && 713 (!f->f_mapping->a_ops->get_xip_page))) { 714 fput(f); 715 f = ERR_PTR(-EINVAL); 716 } 717 } 718 719 return f; 720 721 cleanup_all: 722 fops_put(f->f_op); 723 if (f->f_mode & FMODE_WRITE) 724 put_write_access(inode); 725 file_kill(f); 726 f->f_path.dentry = NULL; 727 f->f_path.mnt = NULL; 728 cleanup_file: 729 put_filp(f); 730 dput(dentry); 731 mntput(mnt); 732 return ERR_PTR(error); 733 } 734 735 /* 736 * Note that while the flag value (low two bits) for sys_open means: 737 * 00 - read-only 738 * 01 - write-only 739 * 10 - read-write 740 * 11 - special 741 * it is changed into 742 * 00 - no permissions needed 743 * 01 - read-permission 744 * 10 - write-permission 745 * 11 - read-write 746 * for the internal routines (ie open_namei()/follow_link() etc). 00 is 747 * used by symlinks. 748 */ 749 static struct file *do_filp_open(int dfd, const char *filename, int flags, 750 int mode) 751 { 752 int namei_flags, error; 753 struct nameidata nd; 754 755 namei_flags = flags; 756 if ((namei_flags+1) & O_ACCMODE) 757 namei_flags++; 758 759 error = open_namei(dfd, filename, namei_flags, mode, &nd); 760 if (!error) 761 return nameidata_to_filp(&nd, flags); 762 763 return ERR_PTR(error); 764 } 765 766 struct file *filp_open(const char *filename, int flags, int mode) 767 { 768 return do_filp_open(AT_FDCWD, filename, flags, mode); 769 } 770 EXPORT_SYMBOL(filp_open); 771 772 /** 773 * lookup_instantiate_filp - instantiates the open intent filp 774 * @nd: pointer to nameidata 775 * @dentry: pointer to dentry 776 * @open: open callback 777 * 778 * Helper for filesystems that want to use lookup open intents and pass back 779 * a fully instantiated struct file to the caller. 780 * This function is meant to be called from within a filesystem's 781 * lookup method. 782 * Beware of calling it for non-regular files! Those ->open methods might block 783 * (e.g. in fifo_open), leaving you with parent locked (and in case of fifo, 784 * leading to a deadlock, as nobody can open that fifo anymore, because 785 * another process to open fifo will block on locked parent when doing lookup). 786 * Note that in case of error, nd->intent.open.file is destroyed, but the 787 * path information remains valid. 788 * If the open callback is set to NULL, then the standard f_op->open() 789 * filesystem callback is substituted. 790 */ 791 struct file *lookup_instantiate_filp(struct nameidata *nd, struct dentry *dentry, 792 int (*open)(struct inode *, struct file *)) 793 { 794 if (IS_ERR(nd->intent.open.file)) 795 goto out; 796 if (IS_ERR(dentry)) 797 goto out_err; 798 nd->intent.open.file = __dentry_open(dget(dentry), mntget(nd->mnt), 799 nd->intent.open.flags - 1, 800 nd->intent.open.file, 801 open); 802 out: 803 return nd->intent.open.file; 804 out_err: 805 release_open_intent(nd); 806 nd->intent.open.file = (struct file *)dentry; 807 goto out; 808 } 809 EXPORT_SYMBOL_GPL(lookup_instantiate_filp); 810 811 /** 812 * nameidata_to_filp - convert a nameidata to an open filp. 813 * @nd: pointer to nameidata 814 * @flags: open flags 815 * 816 * Note that this function destroys the original nameidata 817 */ 818 struct file *nameidata_to_filp(struct nameidata *nd, int flags) 819 { 820 struct file *filp; 821 822 /* Pick up the filp from the open intent */ 823 filp = nd->intent.open.file; 824 /* Has the filesystem initialised the file for us? */ 825 if (filp->f_path.dentry == NULL) 826 filp = __dentry_open(nd->dentry, nd->mnt, flags, filp, NULL); 827 else 828 path_release(nd); 829 return filp; 830 } 831 832 /* 833 * dentry_open() will have done dput(dentry) and mntput(mnt) if it returns an 834 * error. 835 */ 836 struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags) 837 { 838 int error; 839 struct file *f; 840 841 error = -ENFILE; 842 f = get_empty_filp(); 843 if (f == NULL) { 844 dput(dentry); 845 mntput(mnt); 846 return ERR_PTR(error); 847 } 848 849 return __dentry_open(dentry, mnt, flags, f, NULL); 850 } 851 EXPORT_SYMBOL(dentry_open); 852 853 /* 854 * Find an empty file descriptor entry, and mark it busy. 855 */ 856 int get_unused_fd(void) 857 { 858 struct files_struct * files = current->files; 859 int fd, error; 860 struct fdtable *fdt; 861 862 error = -EMFILE; 863 spin_lock(&files->file_lock); 864 865 repeat: 866 fdt = files_fdtable(files); 867 fd = find_next_zero_bit(fdt->open_fds->fds_bits, 868 fdt->max_fdset, 869 files->next_fd); 870 871 /* 872 * N.B. For clone tasks sharing a files structure, this test 873 * will limit the total number of files that can be opened. 874 */ 875 if (fd >= current->signal->rlim[RLIMIT_NOFILE].rlim_cur) 876 goto out; 877 878 /* Do we need to expand the fd array or fd set? */ 879 error = expand_files(files, fd); 880 if (error < 0) 881 goto out; 882 883 if (error) { 884 /* 885 * If we needed to expand the fs array we 886 * might have blocked - try again. 887 */ 888 error = -EMFILE; 889 goto repeat; 890 } 891 892 FD_SET(fd, fdt->open_fds); 893 FD_CLR(fd, fdt->close_on_exec); 894 files->next_fd = fd + 1; 895 #if 1 896 /* Sanity check */ 897 if (fdt->fd[fd] != NULL) { 898 printk(KERN_WARNING "get_unused_fd: slot %d not NULL!\n", fd); 899 fdt->fd[fd] = NULL; 900 } 901 #endif 902 error = fd; 903 904 out: 905 spin_unlock(&files->file_lock); 906 return error; 907 } 908 909 EXPORT_SYMBOL(get_unused_fd); 910 911 static void __put_unused_fd(struct files_struct *files, unsigned int fd) 912 { 913 struct fdtable *fdt = files_fdtable(files); 914 __FD_CLR(fd, fdt->open_fds); 915 if (fd < files->next_fd) 916 files->next_fd = fd; 917 } 918 919 void fastcall put_unused_fd(unsigned int fd) 920 { 921 struct files_struct *files = current->files; 922 spin_lock(&files->file_lock); 923 __put_unused_fd(files, fd); 924 spin_unlock(&files->file_lock); 925 } 926 927 EXPORT_SYMBOL(put_unused_fd); 928 929 /* 930 * Install a file pointer in the fd array. 931 * 932 * The VFS is full of places where we drop the files lock between 933 * setting the open_fds bitmap and installing the file in the file 934 * array. At any such point, we are vulnerable to a dup2() race 935 * installing a file in the array before us. We need to detect this and 936 * fput() the struct file we are about to overwrite in this case. 937 * 938 * It should never happen - if we allow dup2() do it, _really_ bad things 939 * will follow. 940 */ 941 942 void fastcall fd_install(unsigned int fd, struct file * file) 943 { 944 struct files_struct *files = current->files; 945 struct fdtable *fdt; 946 spin_lock(&files->file_lock); 947 fdt = files_fdtable(files); 948 BUG_ON(fdt->fd[fd] != NULL); 949 rcu_assign_pointer(fdt->fd[fd], file); 950 spin_unlock(&files->file_lock); 951 } 952 953 EXPORT_SYMBOL(fd_install); 954 955 long do_sys_open(int dfd, const char __user *filename, int flags, int mode) 956 { 957 char *tmp = getname(filename); 958 int fd = PTR_ERR(tmp); 959 960 if (!IS_ERR(tmp)) { 961 fd = get_unused_fd(); 962 if (fd >= 0) { 963 struct file *f = do_filp_open(dfd, tmp, flags, mode); 964 if (IS_ERR(f)) { 965 put_unused_fd(fd); 966 fd = PTR_ERR(f); 967 } else { 968 fsnotify_open(f->f_path.dentry); 969 fd_install(fd, f); 970 } 971 } 972 putname(tmp); 973 } 974 return fd; 975 } 976 977 asmlinkage long sys_open(const char __user *filename, int flags, int mode) 978 { 979 long ret; 980 981 if (force_o_largefile()) 982 flags |= O_LARGEFILE; 983 984 ret = do_sys_open(AT_FDCWD, filename, flags, mode); 985 /* avoid REGPARM breakage on x86: */ 986 prevent_tail_call(ret); 987 return ret; 988 } 989 EXPORT_SYMBOL_GPL(sys_open); 990 991 asmlinkage long sys_openat(int dfd, const char __user *filename, int flags, 992 int mode) 993 { 994 long ret; 995 996 if (force_o_largefile()) 997 flags |= O_LARGEFILE; 998 999 ret = do_sys_open(dfd, filename, flags, mode); 1000 /* avoid REGPARM breakage on x86: */ 1001 prevent_tail_call(ret); 1002 return ret; 1003 } 1004 1005 #ifndef __alpha__ 1006 1007 /* 1008 * For backward compatibility? Maybe this should be moved 1009 * into arch/i386 instead? 1010 */ 1011 asmlinkage long sys_creat(const char __user * pathname, int mode) 1012 { 1013 return sys_open(pathname, O_CREAT | O_WRONLY | O_TRUNC, mode); 1014 } 1015 1016 #endif 1017 1018 /* 1019 * "id" is the POSIX thread ID. We use the 1020 * files pointer for this.. 1021 */ 1022 int filp_close(struct file *filp, fl_owner_t id) 1023 { 1024 int retval = 0; 1025 1026 if (!file_count(filp)) { 1027 printk(KERN_ERR "VFS: Close: file count is 0\n"); 1028 return 0; 1029 } 1030 1031 if (filp->f_op && filp->f_op->flush) 1032 retval = filp->f_op->flush(filp, id); 1033 1034 dnotify_flush(filp, id); 1035 locks_remove_posix(filp, id); 1036 fput(filp); 1037 return retval; 1038 } 1039 1040 EXPORT_SYMBOL(filp_close); 1041 1042 /* 1043 * Careful here! We test whether the file pointer is NULL before 1044 * releasing the fd. This ensures that one clone task can't release 1045 * an fd while another clone is opening it. 1046 */ 1047 asmlinkage long sys_close(unsigned int fd) 1048 { 1049 struct file * filp; 1050 struct files_struct *files = current->files; 1051 struct fdtable *fdt; 1052 int retval; 1053 1054 spin_lock(&files->file_lock); 1055 fdt = files_fdtable(files); 1056 if (fd >= fdt->max_fds) 1057 goto out_unlock; 1058 filp = fdt->fd[fd]; 1059 if (!filp) 1060 goto out_unlock; 1061 rcu_assign_pointer(fdt->fd[fd], NULL); 1062 FD_CLR(fd, fdt->close_on_exec); 1063 __put_unused_fd(files, fd); 1064 spin_unlock(&files->file_lock); 1065 retval = filp_close(filp, files); 1066 1067 /* can't restart close syscall because file table entry was cleared */ 1068 if (unlikely(retval == -ERESTARTSYS || 1069 retval == -ERESTARTNOINTR || 1070 retval == -ERESTARTNOHAND || 1071 retval == -ERESTART_RESTARTBLOCK)) 1072 retval = -EINTR; 1073 1074 return retval; 1075 1076 out_unlock: 1077 spin_unlock(&files->file_lock); 1078 return -EBADF; 1079 } 1080 1081 EXPORT_SYMBOL(sys_close); 1082 1083 /* 1084 * This routine simulates a hangup on the tty, to arrange that users 1085 * are given clean terminals at login time. 1086 */ 1087 asmlinkage long sys_vhangup(void) 1088 { 1089 if (capable(CAP_SYS_TTY_CONFIG)) { 1090 /* XXX: this needs locking */ 1091 tty_vhangup(current->signal->tty); 1092 return 0; 1093 } 1094 return -EPERM; 1095 } 1096 1097 /* 1098 * Called when an inode is about to be open. 1099 * We use this to disallow opening large files on 32bit systems if 1100 * the caller didn't specify O_LARGEFILE. On 64bit systems we force 1101 * on this flag in sys_open. 1102 */ 1103 int generic_file_open(struct inode * inode, struct file * filp) 1104 { 1105 if (!(filp->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS) 1106 return -EFBIG; 1107 return 0; 1108 } 1109 1110 EXPORT_SYMBOL(generic_file_open); 1111 1112 /* 1113 * This is used by subsystems that don't want seekable 1114 * file descriptors 1115 */ 1116 int nonseekable_open(struct inode *inode, struct file *filp) 1117 { 1118 filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE); 1119 return 0; 1120 } 1121 1122 EXPORT_SYMBOL(nonseekable_open); 1123