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/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/securebits.h> 20 #include <linux/security.h> 21 #include <linux/mount.h> 22 #include <linux/vfs.h> 23 #include <linux/fcntl.h> 24 #include <asm/uaccess.h> 25 #include <linux/fs.h> 26 #include <linux/personality.h> 27 #include <linux/pagemap.h> 28 #include <linux/syscalls.h> 29 #include <linux/rcupdate.h> 30 #include <linux/audit.h> 31 #include <linux/falloc.h> 32 33 int vfs_statfs(struct dentry *dentry, struct kstatfs *buf) 34 { 35 int retval = -ENODEV; 36 37 if (dentry) { 38 retval = -ENOSYS; 39 if (dentry->d_sb->s_op->statfs) { 40 memset(buf, 0, sizeof(*buf)); 41 retval = security_sb_statfs(dentry); 42 if (retval) 43 return retval; 44 retval = dentry->d_sb->s_op->statfs(dentry, buf); 45 if (retval == 0 && buf->f_frsize == 0) 46 buf->f_frsize = buf->f_bsize; 47 } 48 } 49 return retval; 50 } 51 52 EXPORT_SYMBOL(vfs_statfs); 53 54 static int vfs_statfs_native(struct dentry *dentry, struct statfs *buf) 55 { 56 struct kstatfs st; 57 int retval; 58 59 retval = vfs_statfs(dentry, &st); 60 if (retval) 61 return retval; 62 63 if (sizeof(*buf) == sizeof(st)) 64 memcpy(buf, &st, sizeof(st)); 65 else { 66 if (sizeof buf->f_blocks == 4) { 67 if ((st.f_blocks | st.f_bfree | st.f_bavail | 68 st.f_bsize | st.f_frsize) & 69 0xffffffff00000000ULL) 70 return -EOVERFLOW; 71 /* 72 * f_files and f_ffree may be -1; it's okay to stuff 73 * that into 32 bits 74 */ 75 if (st.f_files != -1 && 76 (st.f_files & 0xffffffff00000000ULL)) 77 return -EOVERFLOW; 78 if (st.f_ffree != -1 && 79 (st.f_ffree & 0xffffffff00000000ULL)) 80 return -EOVERFLOW; 81 } 82 83 buf->f_type = st.f_type; 84 buf->f_bsize = st.f_bsize; 85 buf->f_blocks = st.f_blocks; 86 buf->f_bfree = st.f_bfree; 87 buf->f_bavail = st.f_bavail; 88 buf->f_files = st.f_files; 89 buf->f_ffree = st.f_ffree; 90 buf->f_fsid = st.f_fsid; 91 buf->f_namelen = st.f_namelen; 92 buf->f_frsize = st.f_frsize; 93 memset(buf->f_spare, 0, sizeof(buf->f_spare)); 94 } 95 return 0; 96 } 97 98 static int vfs_statfs64(struct dentry *dentry, struct statfs64 *buf) 99 { 100 struct kstatfs st; 101 int retval; 102 103 retval = vfs_statfs(dentry, &st); 104 if (retval) 105 return retval; 106 107 if (sizeof(*buf) == sizeof(st)) 108 memcpy(buf, &st, sizeof(st)); 109 else { 110 buf->f_type = st.f_type; 111 buf->f_bsize = st.f_bsize; 112 buf->f_blocks = st.f_blocks; 113 buf->f_bfree = st.f_bfree; 114 buf->f_bavail = st.f_bavail; 115 buf->f_files = st.f_files; 116 buf->f_ffree = st.f_ffree; 117 buf->f_fsid = st.f_fsid; 118 buf->f_namelen = st.f_namelen; 119 buf->f_frsize = st.f_frsize; 120 memset(buf->f_spare, 0, sizeof(buf->f_spare)); 121 } 122 return 0; 123 } 124 125 asmlinkage long sys_statfs(const char __user * path, struct statfs __user * buf) 126 { 127 struct nameidata nd; 128 int error; 129 130 error = user_path_walk(path, &nd); 131 if (!error) { 132 struct statfs tmp; 133 error = vfs_statfs_native(nd.path.dentry, &tmp); 134 if (!error && copy_to_user(buf, &tmp, sizeof(tmp))) 135 error = -EFAULT; 136 path_put(&nd.path); 137 } 138 return error; 139 } 140 141 142 asmlinkage long sys_statfs64(const char __user *path, size_t sz, struct statfs64 __user *buf) 143 { 144 struct nameidata nd; 145 long error; 146 147 if (sz != sizeof(*buf)) 148 return -EINVAL; 149 error = user_path_walk(path, &nd); 150 if (!error) { 151 struct statfs64 tmp; 152 error = vfs_statfs64(nd.path.dentry, &tmp); 153 if (!error && copy_to_user(buf, &tmp, sizeof(tmp))) 154 error = -EFAULT; 155 path_put(&nd.path); 156 } 157 return error; 158 } 159 160 161 asmlinkage long sys_fstatfs(unsigned int fd, struct statfs __user * buf) 162 { 163 struct file * file; 164 struct statfs tmp; 165 int error; 166 167 error = -EBADF; 168 file = fget(fd); 169 if (!file) 170 goto out; 171 error = vfs_statfs_native(file->f_path.dentry, &tmp); 172 if (!error && copy_to_user(buf, &tmp, sizeof(tmp))) 173 error = -EFAULT; 174 fput(file); 175 out: 176 return error; 177 } 178 179 asmlinkage long sys_fstatfs64(unsigned int fd, size_t sz, struct statfs64 __user *buf) 180 { 181 struct file * file; 182 struct statfs64 tmp; 183 int error; 184 185 if (sz != sizeof(*buf)) 186 return -EINVAL; 187 188 error = -EBADF; 189 file = fget(fd); 190 if (!file) 191 goto out; 192 error = vfs_statfs64(file->f_path.dentry, &tmp); 193 if (!error && copy_to_user(buf, &tmp, sizeof(tmp))) 194 error = -EFAULT; 195 fput(file); 196 out: 197 return error; 198 } 199 200 int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs, 201 struct file *filp) 202 { 203 int err; 204 struct iattr newattrs; 205 206 /* Not pretty: "inode->i_size" shouldn't really be signed. But it is. */ 207 if (length < 0) 208 return -EINVAL; 209 210 newattrs.ia_size = length; 211 newattrs.ia_valid = ATTR_SIZE | time_attrs; 212 if (filp) { 213 newattrs.ia_file = filp; 214 newattrs.ia_valid |= ATTR_FILE; 215 } 216 217 /* Remove suid/sgid on truncate too */ 218 newattrs.ia_valid |= should_remove_suid(dentry); 219 220 mutex_lock(&dentry->d_inode->i_mutex); 221 err = notify_change(dentry, &newattrs); 222 mutex_unlock(&dentry->d_inode->i_mutex); 223 return err; 224 } 225 226 static long do_sys_truncate(const char __user * path, loff_t length) 227 { 228 struct nameidata nd; 229 struct inode * inode; 230 int error; 231 232 error = -EINVAL; 233 if (length < 0) /* sorry, but loff_t says... */ 234 goto out; 235 236 error = user_path_walk(path, &nd); 237 if (error) 238 goto out; 239 inode = nd.path.dentry->d_inode; 240 241 /* For directories it's -EISDIR, for other non-regulars - -EINVAL */ 242 error = -EISDIR; 243 if (S_ISDIR(inode->i_mode)) 244 goto dput_and_out; 245 246 error = -EINVAL; 247 if (!S_ISREG(inode->i_mode)) 248 goto dput_and_out; 249 250 error = mnt_want_write(nd.path.mnt); 251 if (error) 252 goto dput_and_out; 253 254 error = vfs_permission(&nd, MAY_WRITE); 255 if (error) 256 goto mnt_drop_write_and_out; 257 258 error = -EPERM; 259 if (IS_IMMUTABLE(inode) || IS_APPEND(inode)) 260 goto mnt_drop_write_and_out; 261 262 error = get_write_access(inode); 263 if (error) 264 goto mnt_drop_write_and_out; 265 266 /* 267 * Make sure that there are no leases. get_write_access() protects 268 * against the truncate racing with a lease-granting setlease(). 269 */ 270 error = break_lease(inode, FMODE_WRITE); 271 if (error) 272 goto put_write_and_out; 273 274 error = locks_verify_truncate(inode, NULL, length); 275 if (!error) { 276 DQUOT_INIT(inode); 277 error = do_truncate(nd.path.dentry, length, 0, NULL); 278 } 279 280 put_write_and_out: 281 put_write_access(inode); 282 mnt_drop_write_and_out: 283 mnt_drop_write(nd.path.mnt); 284 dput_and_out: 285 path_put(&nd.path); 286 out: 287 return error; 288 } 289 290 asmlinkage long sys_truncate(const char __user * path, unsigned long length) 291 { 292 /* on 32-bit boxen it will cut the range 2^31--2^32-1 off */ 293 return do_sys_truncate(path, (long)length); 294 } 295 296 static long do_sys_ftruncate(unsigned int fd, loff_t length, int small) 297 { 298 struct inode * inode; 299 struct dentry *dentry; 300 struct file * file; 301 int error; 302 303 error = -EINVAL; 304 if (length < 0) 305 goto out; 306 error = -EBADF; 307 file = fget(fd); 308 if (!file) 309 goto out; 310 311 /* explicitly opened as large or we are on 64-bit box */ 312 if (file->f_flags & O_LARGEFILE) 313 small = 0; 314 315 dentry = file->f_path.dentry; 316 inode = dentry->d_inode; 317 error = -EINVAL; 318 if (!S_ISREG(inode->i_mode) || !(file->f_mode & FMODE_WRITE)) 319 goto out_putf; 320 321 error = -EINVAL; 322 /* Cannot ftruncate over 2^31 bytes without large file support */ 323 if (small && length > MAX_NON_LFS) 324 goto out_putf; 325 326 error = -EPERM; 327 if (IS_APPEND(inode)) 328 goto out_putf; 329 330 error = locks_verify_truncate(inode, file, length); 331 if (!error) 332 error = do_truncate(dentry, length, ATTR_MTIME|ATTR_CTIME, file); 333 out_putf: 334 fput(file); 335 out: 336 return error; 337 } 338 339 asmlinkage long sys_ftruncate(unsigned int fd, unsigned long length) 340 { 341 long ret = do_sys_ftruncate(fd, length, 1); 342 /* avoid REGPARM breakage on x86: */ 343 asmlinkage_protect(2, ret, fd, length); 344 return ret; 345 } 346 347 /* LFS versions of truncate are only needed on 32 bit machines */ 348 #if BITS_PER_LONG == 32 349 asmlinkage long sys_truncate64(const char __user * path, loff_t length) 350 { 351 return do_sys_truncate(path, length); 352 } 353 354 asmlinkage long sys_ftruncate64(unsigned int fd, loff_t length) 355 { 356 long ret = do_sys_ftruncate(fd, length, 0); 357 /* avoid REGPARM breakage on x86: */ 358 asmlinkage_protect(2, ret, fd, length); 359 return ret; 360 } 361 #endif 362 363 asmlinkage long sys_fallocate(int fd, int mode, loff_t offset, loff_t len) 364 { 365 struct file *file; 366 struct inode *inode; 367 long ret = -EINVAL; 368 369 if (offset < 0 || len <= 0) 370 goto out; 371 372 /* Return error if mode is not supported */ 373 ret = -EOPNOTSUPP; 374 if (mode && !(mode & FALLOC_FL_KEEP_SIZE)) 375 goto out; 376 377 ret = -EBADF; 378 file = fget(fd); 379 if (!file) 380 goto out; 381 if (!(file->f_mode & FMODE_WRITE)) 382 goto out_fput; 383 /* 384 * Revalidate the write permissions, in case security policy has 385 * changed since the files were opened. 386 */ 387 ret = security_file_permission(file, MAY_WRITE); 388 if (ret) 389 goto out_fput; 390 391 inode = file->f_path.dentry->d_inode; 392 393 ret = -ESPIPE; 394 if (S_ISFIFO(inode->i_mode)) 395 goto out_fput; 396 397 ret = -ENODEV; 398 /* 399 * Let individual file system decide if it supports preallocation 400 * for directories or not. 401 */ 402 if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode)) 403 goto out_fput; 404 405 ret = -EFBIG; 406 /* Check for wrap through zero too */ 407 if (((offset + len) > inode->i_sb->s_maxbytes) || ((offset + len) < 0)) 408 goto out_fput; 409 410 if (inode->i_op && inode->i_op->fallocate) 411 ret = inode->i_op->fallocate(inode, mode, offset, len); 412 else 413 ret = -EOPNOTSUPP; 414 415 out_fput: 416 fput(file); 417 out: 418 return ret; 419 } 420 421 /* 422 * access() needs to use the real uid/gid, not the effective uid/gid. 423 * We do this by temporarily clearing all FS-related capabilities and 424 * switching the fsuid/fsgid around to the real ones. 425 */ 426 asmlinkage long sys_faccessat(int dfd, const char __user *filename, int mode) 427 { 428 struct nameidata nd; 429 int old_fsuid, old_fsgid; 430 kernel_cap_t uninitialized_var(old_cap); /* !SECURE_NO_SETUID_FIXUP */ 431 int res; 432 433 if (mode & ~S_IRWXO) /* where's F_OK, X_OK, W_OK, R_OK? */ 434 return -EINVAL; 435 436 old_fsuid = current->fsuid; 437 old_fsgid = current->fsgid; 438 439 current->fsuid = current->uid; 440 current->fsgid = current->gid; 441 442 if (!issecure(SECURE_NO_SETUID_FIXUP)) { 443 /* 444 * Clear the capabilities if we switch to a non-root user 445 */ 446 #ifndef CONFIG_SECURITY_FILE_CAPABILITIES 447 /* 448 * FIXME: There is a race here against sys_capset. The 449 * capabilities can change yet we will restore the old 450 * value below. We should hold task_capabilities_lock, 451 * but we cannot because user_path_walk can sleep. 452 */ 453 #endif /* ndef CONFIG_SECURITY_FILE_CAPABILITIES */ 454 if (current->uid) 455 old_cap = cap_set_effective(__cap_empty_set); 456 else 457 old_cap = cap_set_effective(current->cap_permitted); 458 } 459 460 res = __user_walk_fd(dfd, filename, LOOKUP_FOLLOW|LOOKUP_ACCESS, &nd); 461 if (res) 462 goto out; 463 464 res = vfs_permission(&nd, mode); 465 /* SuS v2 requires we report a read only fs too */ 466 if(res || !(mode & S_IWOTH) || 467 special_file(nd.path.dentry->d_inode->i_mode)) 468 goto out_path_release; 469 /* 470 * This is a rare case where using __mnt_is_readonly() 471 * is OK without a mnt_want/drop_write() pair. Since 472 * no actual write to the fs is performed here, we do 473 * not need to telegraph to that to anyone. 474 * 475 * By doing this, we accept that this access is 476 * inherently racy and know that the fs may change 477 * state before we even see this result. 478 */ 479 if (__mnt_is_readonly(nd.path.mnt)) 480 res = -EROFS; 481 482 out_path_release: 483 path_put(&nd.path); 484 out: 485 current->fsuid = old_fsuid; 486 current->fsgid = old_fsgid; 487 488 if (!issecure(SECURE_NO_SETUID_FIXUP)) 489 cap_set_effective(old_cap); 490 491 return res; 492 } 493 494 asmlinkage long sys_access(const char __user *filename, int mode) 495 { 496 return sys_faccessat(AT_FDCWD, filename, mode); 497 } 498 499 asmlinkage long sys_chdir(const char __user * filename) 500 { 501 struct nameidata nd; 502 int error; 503 504 error = __user_walk(filename, 505 LOOKUP_FOLLOW|LOOKUP_DIRECTORY|LOOKUP_CHDIR, &nd); 506 if (error) 507 goto out; 508 509 error = vfs_permission(&nd, MAY_EXEC); 510 if (error) 511 goto dput_and_out; 512 513 set_fs_pwd(current->fs, &nd.path); 514 515 dput_and_out: 516 path_put(&nd.path); 517 out: 518 return error; 519 } 520 521 asmlinkage long sys_fchdir(unsigned int fd) 522 { 523 struct file *file; 524 struct inode *inode; 525 int error; 526 527 error = -EBADF; 528 file = fget(fd); 529 if (!file) 530 goto out; 531 532 inode = file->f_path.dentry->d_inode; 533 534 error = -ENOTDIR; 535 if (!S_ISDIR(inode->i_mode)) 536 goto out_putf; 537 538 error = file_permission(file, MAY_EXEC); 539 if (!error) 540 set_fs_pwd(current->fs, &file->f_path); 541 out_putf: 542 fput(file); 543 out: 544 return error; 545 } 546 547 asmlinkage long sys_chroot(const char __user * filename) 548 { 549 struct nameidata nd; 550 int error; 551 552 error = __user_walk(filename, LOOKUP_FOLLOW | LOOKUP_DIRECTORY | LOOKUP_NOALT, &nd); 553 if (error) 554 goto out; 555 556 error = vfs_permission(&nd, MAY_EXEC); 557 if (error) 558 goto dput_and_out; 559 560 error = -EPERM; 561 if (!capable(CAP_SYS_CHROOT)) 562 goto dput_and_out; 563 564 set_fs_root(current->fs, &nd.path); 565 set_fs_altroot(); 566 error = 0; 567 dput_and_out: 568 path_put(&nd.path); 569 out: 570 return error; 571 } 572 573 asmlinkage long sys_fchmod(unsigned int fd, mode_t mode) 574 { 575 struct inode * inode; 576 struct dentry * dentry; 577 struct file * file; 578 int err = -EBADF; 579 struct iattr newattrs; 580 581 file = fget(fd); 582 if (!file) 583 goto out; 584 585 dentry = file->f_path.dentry; 586 inode = dentry->d_inode; 587 588 audit_inode(NULL, dentry); 589 590 err = mnt_want_write(file->f_path.mnt); 591 if (err) 592 goto out_putf; 593 err = -EPERM; 594 if (IS_IMMUTABLE(inode) || IS_APPEND(inode)) 595 goto out_drop_write; 596 mutex_lock(&inode->i_mutex); 597 if (mode == (mode_t) -1) 598 mode = inode->i_mode; 599 newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO); 600 newattrs.ia_valid = ATTR_MODE | ATTR_CTIME; 601 err = notify_change(dentry, &newattrs); 602 mutex_unlock(&inode->i_mutex); 603 604 out_drop_write: 605 mnt_drop_write(file->f_path.mnt); 606 out_putf: 607 fput(file); 608 out: 609 return err; 610 } 611 612 asmlinkage long sys_fchmodat(int dfd, const char __user *filename, 613 mode_t mode) 614 { 615 struct nameidata nd; 616 struct inode * inode; 617 int error; 618 struct iattr newattrs; 619 620 error = __user_walk_fd(dfd, filename, LOOKUP_FOLLOW, &nd); 621 if (error) 622 goto out; 623 inode = nd.path.dentry->d_inode; 624 625 error = mnt_want_write(nd.path.mnt); 626 if (error) 627 goto dput_and_out; 628 629 error = -EPERM; 630 if (IS_IMMUTABLE(inode) || IS_APPEND(inode)) 631 goto out_drop_write; 632 633 mutex_lock(&inode->i_mutex); 634 if (mode == (mode_t) -1) 635 mode = inode->i_mode; 636 newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO); 637 newattrs.ia_valid = ATTR_MODE | ATTR_CTIME; 638 error = notify_change(nd.path.dentry, &newattrs); 639 mutex_unlock(&inode->i_mutex); 640 641 out_drop_write: 642 mnt_drop_write(nd.path.mnt); 643 dput_and_out: 644 path_put(&nd.path); 645 out: 646 return error; 647 } 648 649 asmlinkage long sys_chmod(const char __user *filename, mode_t mode) 650 { 651 return sys_fchmodat(AT_FDCWD, filename, mode); 652 } 653 654 static int chown_common(struct dentry * dentry, uid_t user, gid_t group) 655 { 656 struct inode * inode; 657 int error; 658 struct iattr newattrs; 659 660 error = -ENOENT; 661 if (!(inode = dentry->d_inode)) { 662 printk(KERN_ERR "chown_common: NULL inode\n"); 663 goto out; 664 } 665 error = -EPERM; 666 if (IS_IMMUTABLE(inode) || IS_APPEND(inode)) 667 goto out; 668 newattrs.ia_valid = ATTR_CTIME; 669 if (user != (uid_t) -1) { 670 newattrs.ia_valid |= ATTR_UID; 671 newattrs.ia_uid = user; 672 } 673 if (group != (gid_t) -1) { 674 newattrs.ia_valid |= ATTR_GID; 675 newattrs.ia_gid = group; 676 } 677 if (!S_ISDIR(inode->i_mode)) 678 newattrs.ia_valid |= 679 ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_KILL_PRIV; 680 mutex_lock(&inode->i_mutex); 681 error = notify_change(dentry, &newattrs); 682 mutex_unlock(&inode->i_mutex); 683 out: 684 return error; 685 } 686 687 asmlinkage long sys_chown(const char __user * filename, uid_t user, gid_t group) 688 { 689 struct nameidata nd; 690 int error; 691 692 error = user_path_walk(filename, &nd); 693 if (error) 694 goto out; 695 error = mnt_want_write(nd.path.mnt); 696 if (error) 697 goto out_release; 698 error = chown_common(nd.path.dentry, user, group); 699 mnt_drop_write(nd.path.mnt); 700 out_release: 701 path_put(&nd.path); 702 out: 703 return error; 704 } 705 706 asmlinkage long sys_fchownat(int dfd, const char __user *filename, uid_t user, 707 gid_t group, int flag) 708 { 709 struct nameidata nd; 710 int error = -EINVAL; 711 int follow; 712 713 if ((flag & ~AT_SYMLINK_NOFOLLOW) != 0) 714 goto out; 715 716 follow = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW; 717 error = __user_walk_fd(dfd, filename, follow, &nd); 718 if (error) 719 goto out; 720 error = mnt_want_write(nd.path.mnt); 721 if (error) 722 goto out_release; 723 error = chown_common(nd.path.dentry, user, group); 724 mnt_drop_write(nd.path.mnt); 725 out_release: 726 path_put(&nd.path); 727 out: 728 return error; 729 } 730 731 asmlinkage long sys_lchown(const char __user * filename, uid_t user, gid_t group) 732 { 733 struct nameidata nd; 734 int error; 735 736 error = user_path_walk_link(filename, &nd); 737 if (error) 738 goto out; 739 error = mnt_want_write(nd.path.mnt); 740 if (error) 741 goto out_release; 742 error = chown_common(nd.path.dentry, user, group); 743 mnt_drop_write(nd.path.mnt); 744 out_release: 745 path_put(&nd.path); 746 out: 747 return error; 748 } 749 750 751 asmlinkage long sys_fchown(unsigned int fd, uid_t user, gid_t group) 752 { 753 struct file * file; 754 int error = -EBADF; 755 struct dentry * dentry; 756 757 file = fget(fd); 758 if (!file) 759 goto out; 760 761 error = mnt_want_write(file->f_path.mnt); 762 if (error) 763 goto out_fput; 764 dentry = file->f_path.dentry; 765 audit_inode(NULL, dentry); 766 error = chown_common(dentry, user, group); 767 mnt_drop_write(file->f_path.mnt); 768 out_fput: 769 fput(file); 770 out: 771 return error; 772 } 773 774 /* 775 * You have to be very careful that these write 776 * counts get cleaned up in error cases and 777 * upon __fput(). This should probably never 778 * be called outside of __dentry_open(). 779 */ 780 static inline int __get_file_write_access(struct inode *inode, 781 struct vfsmount *mnt) 782 { 783 int error; 784 error = get_write_access(inode); 785 if (error) 786 return error; 787 /* 788 * Do not take mount writer counts on 789 * special files since no writes to 790 * the mount itself will occur. 791 */ 792 if (!special_file(inode->i_mode)) { 793 /* 794 * Balanced in __fput() 795 */ 796 error = mnt_want_write(mnt); 797 if (error) 798 put_write_access(inode); 799 } 800 return error; 801 } 802 803 static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt, 804 int flags, struct file *f, 805 int (*open)(struct inode *, struct file *)) 806 { 807 struct inode *inode; 808 int error; 809 810 f->f_flags = flags; 811 f->f_mode = ((flags+1) & O_ACCMODE) | FMODE_LSEEK | 812 FMODE_PREAD | FMODE_PWRITE; 813 inode = dentry->d_inode; 814 if (f->f_mode & FMODE_WRITE) { 815 error = __get_file_write_access(inode, mnt); 816 if (error) 817 goto cleanup_file; 818 if (!special_file(inode->i_mode)) 819 file_take_write(f); 820 } 821 822 f->f_mapping = inode->i_mapping; 823 f->f_path.dentry = dentry; 824 f->f_path.mnt = mnt; 825 f->f_pos = 0; 826 f->f_op = fops_get(inode->i_fop); 827 file_move(f, &inode->i_sb->s_files); 828 829 error = security_dentry_open(f); 830 if (error) 831 goto cleanup_all; 832 833 if (!open && f->f_op) 834 open = f->f_op->open; 835 if (open) { 836 error = open(inode, f); 837 if (error) 838 goto cleanup_all; 839 } 840 841 f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC); 842 843 file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping); 844 845 /* NB: we're sure to have correct a_ops only after f_op->open */ 846 if (f->f_flags & O_DIRECT) { 847 if (!f->f_mapping->a_ops || 848 ((!f->f_mapping->a_ops->direct_IO) && 849 (!f->f_mapping->a_ops->get_xip_mem))) { 850 fput(f); 851 f = ERR_PTR(-EINVAL); 852 } 853 } 854 855 return f; 856 857 cleanup_all: 858 fops_put(f->f_op); 859 if (f->f_mode & FMODE_WRITE) { 860 put_write_access(inode); 861 if (!special_file(inode->i_mode)) { 862 /* 863 * We don't consider this a real 864 * mnt_want/drop_write() pair 865 * because it all happenend right 866 * here, so just reset the state. 867 */ 868 file_reset_write(f); 869 mnt_drop_write(mnt); 870 } 871 } 872 file_kill(f); 873 f->f_path.dentry = NULL; 874 f->f_path.mnt = NULL; 875 cleanup_file: 876 put_filp(f); 877 dput(dentry); 878 mntput(mnt); 879 return ERR_PTR(error); 880 } 881 882 /** 883 * lookup_instantiate_filp - instantiates the open intent filp 884 * @nd: pointer to nameidata 885 * @dentry: pointer to dentry 886 * @open: open callback 887 * 888 * Helper for filesystems that want to use lookup open intents and pass back 889 * a fully instantiated struct file to the caller. 890 * This function is meant to be called from within a filesystem's 891 * lookup method. 892 * Beware of calling it for non-regular files! Those ->open methods might block 893 * (e.g. in fifo_open), leaving you with parent locked (and in case of fifo, 894 * leading to a deadlock, as nobody can open that fifo anymore, because 895 * another process to open fifo will block on locked parent when doing lookup). 896 * Note that in case of error, nd->intent.open.file is destroyed, but the 897 * path information remains valid. 898 * If the open callback is set to NULL, then the standard f_op->open() 899 * filesystem callback is substituted. 900 */ 901 struct file *lookup_instantiate_filp(struct nameidata *nd, struct dentry *dentry, 902 int (*open)(struct inode *, struct file *)) 903 { 904 if (IS_ERR(nd->intent.open.file)) 905 goto out; 906 if (IS_ERR(dentry)) 907 goto out_err; 908 nd->intent.open.file = __dentry_open(dget(dentry), mntget(nd->path.mnt), 909 nd->intent.open.flags - 1, 910 nd->intent.open.file, 911 open); 912 out: 913 return nd->intent.open.file; 914 out_err: 915 release_open_intent(nd); 916 nd->intent.open.file = (struct file *)dentry; 917 goto out; 918 } 919 EXPORT_SYMBOL_GPL(lookup_instantiate_filp); 920 921 /** 922 * nameidata_to_filp - convert a nameidata to an open filp. 923 * @nd: pointer to nameidata 924 * @flags: open flags 925 * 926 * Note that this function destroys the original nameidata 927 */ 928 struct file *nameidata_to_filp(struct nameidata *nd, int flags) 929 { 930 struct file *filp; 931 932 /* Pick up the filp from the open intent */ 933 filp = nd->intent.open.file; 934 /* Has the filesystem initialised the file for us? */ 935 if (filp->f_path.dentry == NULL) 936 filp = __dentry_open(nd->path.dentry, nd->path.mnt, flags, filp, 937 NULL); 938 else 939 path_put(&nd->path); 940 return filp; 941 } 942 943 /* 944 * dentry_open() will have done dput(dentry) and mntput(mnt) if it returns an 945 * error. 946 */ 947 struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags) 948 { 949 int error; 950 struct file *f; 951 952 /* 953 * We must always pass in a valid mount pointer. Historically 954 * callers got away with not passing it, but we must enforce this at 955 * the earliest possible point now to avoid strange problems deep in the 956 * filesystem stack. 957 */ 958 if (!mnt) { 959 printk(KERN_WARNING "%s called with NULL vfsmount\n", __func__); 960 dump_stack(); 961 return ERR_PTR(-EINVAL); 962 } 963 964 error = -ENFILE; 965 f = get_empty_filp(); 966 if (f == NULL) { 967 dput(dentry); 968 mntput(mnt); 969 return ERR_PTR(error); 970 } 971 972 return __dentry_open(dentry, mnt, flags, f, NULL); 973 } 974 EXPORT_SYMBOL(dentry_open); 975 976 /* 977 * Find an empty file descriptor entry, and mark it busy. 978 */ 979 int get_unused_fd_flags(int flags) 980 { 981 struct files_struct * files = current->files; 982 int fd, error; 983 struct fdtable *fdt; 984 985 error = -EMFILE; 986 spin_lock(&files->file_lock); 987 988 repeat: 989 fdt = files_fdtable(files); 990 fd = find_next_zero_bit(fdt->open_fds->fds_bits, fdt->max_fds, 991 files->next_fd); 992 993 /* 994 * N.B. For clone tasks sharing a files structure, this test 995 * will limit the total number of files that can be opened. 996 */ 997 if (fd >= current->signal->rlim[RLIMIT_NOFILE].rlim_cur) 998 goto out; 999 1000 /* Do we need to expand the fd array or fd set? */ 1001 error = expand_files(files, fd); 1002 if (error < 0) 1003 goto out; 1004 1005 if (error) { 1006 /* 1007 * If we needed to expand the fs array we 1008 * might have blocked - try again. 1009 */ 1010 error = -EMFILE; 1011 goto repeat; 1012 } 1013 1014 FD_SET(fd, fdt->open_fds); 1015 if (flags & O_CLOEXEC) 1016 FD_SET(fd, fdt->close_on_exec); 1017 else 1018 FD_CLR(fd, fdt->close_on_exec); 1019 files->next_fd = fd + 1; 1020 #if 1 1021 /* Sanity check */ 1022 if (fdt->fd[fd] != NULL) { 1023 printk(KERN_WARNING "get_unused_fd: slot %d not NULL!\n", fd); 1024 fdt->fd[fd] = NULL; 1025 } 1026 #endif 1027 error = fd; 1028 1029 out: 1030 spin_unlock(&files->file_lock); 1031 return error; 1032 } 1033 1034 int get_unused_fd(void) 1035 { 1036 return get_unused_fd_flags(0); 1037 } 1038 1039 EXPORT_SYMBOL(get_unused_fd); 1040 1041 static void __put_unused_fd(struct files_struct *files, unsigned int fd) 1042 { 1043 struct fdtable *fdt = files_fdtable(files); 1044 __FD_CLR(fd, fdt->open_fds); 1045 if (fd < files->next_fd) 1046 files->next_fd = fd; 1047 } 1048 1049 void put_unused_fd(unsigned int fd) 1050 { 1051 struct files_struct *files = current->files; 1052 spin_lock(&files->file_lock); 1053 __put_unused_fd(files, fd); 1054 spin_unlock(&files->file_lock); 1055 } 1056 1057 EXPORT_SYMBOL(put_unused_fd); 1058 1059 /* 1060 * Install a file pointer in the fd array. 1061 * 1062 * The VFS is full of places where we drop the files lock between 1063 * setting the open_fds bitmap and installing the file in the file 1064 * array. At any such point, we are vulnerable to a dup2() race 1065 * installing a file in the array before us. We need to detect this and 1066 * fput() the struct file we are about to overwrite in this case. 1067 * 1068 * It should never happen - if we allow dup2() do it, _really_ bad things 1069 * will follow. 1070 */ 1071 1072 void fd_install(unsigned int fd, struct file *file) 1073 { 1074 struct files_struct *files = current->files; 1075 struct fdtable *fdt; 1076 spin_lock(&files->file_lock); 1077 fdt = files_fdtable(files); 1078 BUG_ON(fdt->fd[fd] != NULL); 1079 rcu_assign_pointer(fdt->fd[fd], file); 1080 spin_unlock(&files->file_lock); 1081 } 1082 1083 EXPORT_SYMBOL(fd_install); 1084 1085 long do_sys_open(int dfd, const char __user *filename, int flags, int mode) 1086 { 1087 char *tmp = getname(filename); 1088 int fd = PTR_ERR(tmp); 1089 1090 if (!IS_ERR(tmp)) { 1091 fd = get_unused_fd_flags(flags); 1092 if (fd >= 0) { 1093 struct file *f = do_filp_open(dfd, tmp, flags, mode); 1094 if (IS_ERR(f)) { 1095 put_unused_fd(fd); 1096 fd = PTR_ERR(f); 1097 } else { 1098 fsnotify_open(f->f_path.dentry); 1099 fd_install(fd, f); 1100 } 1101 } 1102 putname(tmp); 1103 } 1104 return fd; 1105 } 1106 1107 asmlinkage long sys_open(const char __user *filename, int flags, int mode) 1108 { 1109 long ret; 1110 1111 if (force_o_largefile()) 1112 flags |= O_LARGEFILE; 1113 1114 ret = do_sys_open(AT_FDCWD, filename, flags, mode); 1115 /* avoid REGPARM breakage on x86: */ 1116 asmlinkage_protect(3, ret, filename, flags, mode); 1117 return ret; 1118 } 1119 1120 asmlinkage long sys_openat(int dfd, const char __user *filename, int flags, 1121 int mode) 1122 { 1123 long ret; 1124 1125 if (force_o_largefile()) 1126 flags |= O_LARGEFILE; 1127 1128 ret = do_sys_open(dfd, filename, flags, mode); 1129 /* avoid REGPARM breakage on x86: */ 1130 asmlinkage_protect(4, ret, dfd, filename, flags, mode); 1131 return ret; 1132 } 1133 1134 #ifndef __alpha__ 1135 1136 /* 1137 * For backward compatibility? Maybe this should be moved 1138 * into arch/i386 instead? 1139 */ 1140 asmlinkage long sys_creat(const char __user * pathname, int mode) 1141 { 1142 return sys_open(pathname, O_CREAT | O_WRONLY | O_TRUNC, mode); 1143 } 1144 1145 #endif 1146 1147 /* 1148 * "id" is the POSIX thread ID. We use the 1149 * files pointer for this.. 1150 */ 1151 int filp_close(struct file *filp, fl_owner_t id) 1152 { 1153 int retval = 0; 1154 1155 if (!file_count(filp)) { 1156 printk(KERN_ERR "VFS: Close: file count is 0\n"); 1157 return 0; 1158 } 1159 1160 if (filp->f_op && filp->f_op->flush) 1161 retval = filp->f_op->flush(filp, id); 1162 1163 dnotify_flush(filp, id); 1164 locks_remove_posix(filp, id); 1165 fput(filp); 1166 return retval; 1167 } 1168 1169 EXPORT_SYMBOL(filp_close); 1170 1171 /* 1172 * Careful here! We test whether the file pointer is NULL before 1173 * releasing the fd. This ensures that one clone task can't release 1174 * an fd while another clone is opening it. 1175 */ 1176 asmlinkage long sys_close(unsigned int fd) 1177 { 1178 struct file * filp; 1179 struct files_struct *files = current->files; 1180 struct fdtable *fdt; 1181 int retval; 1182 1183 spin_lock(&files->file_lock); 1184 fdt = files_fdtable(files); 1185 if (fd >= fdt->max_fds) 1186 goto out_unlock; 1187 filp = fdt->fd[fd]; 1188 if (!filp) 1189 goto out_unlock; 1190 rcu_assign_pointer(fdt->fd[fd], NULL); 1191 FD_CLR(fd, fdt->close_on_exec); 1192 __put_unused_fd(files, fd); 1193 spin_unlock(&files->file_lock); 1194 retval = filp_close(filp, files); 1195 1196 /* can't restart close syscall because file table entry was cleared */ 1197 if (unlikely(retval == -ERESTARTSYS || 1198 retval == -ERESTARTNOINTR || 1199 retval == -ERESTARTNOHAND || 1200 retval == -ERESTART_RESTARTBLOCK)) 1201 retval = -EINTR; 1202 1203 return retval; 1204 1205 out_unlock: 1206 spin_unlock(&files->file_lock); 1207 return -EBADF; 1208 } 1209 1210 EXPORT_SYMBOL(sys_close); 1211 1212 /* 1213 * This routine simulates a hangup on the tty, to arrange that users 1214 * are given clean terminals at login time. 1215 */ 1216 asmlinkage long sys_vhangup(void) 1217 { 1218 if (capable(CAP_SYS_TTY_CONFIG)) { 1219 /* XXX: this needs locking */ 1220 tty_vhangup(current->signal->tty); 1221 return 0; 1222 } 1223 return -EPERM; 1224 } 1225 1226 /* 1227 * Called when an inode is about to be open. 1228 * We use this to disallow opening large files on 32bit systems if 1229 * the caller didn't specify O_LARGEFILE. On 64bit systems we force 1230 * on this flag in sys_open. 1231 */ 1232 int generic_file_open(struct inode * inode, struct file * filp) 1233 { 1234 if (!(filp->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS) 1235 return -EOVERFLOW; 1236 return 0; 1237 } 1238 1239 EXPORT_SYMBOL(generic_file_open); 1240 1241 /* 1242 * This is used by subsystems that don't want seekable 1243 * file descriptors 1244 */ 1245 int nonseekable_open(struct inode *inode, struct file *filp) 1246 { 1247 filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE); 1248 return 0; 1249 } 1250 1251 EXPORT_SYMBOL(nonseekable_open); 1252