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