Linux Audio

Check our new training course

Loading...
v4.6
 
   1/*
   2 *  linux/fs/open.c
   3 *
   4 *  Copyright (C) 1991, 1992  Linus Torvalds
   5 */
   6
   7#include <linux/string.h>
   8#include <linux/mm.h>
   9#include <linux/file.h>
  10#include <linux/fdtable.h>
  11#include <linux/fsnotify.h>
  12#include <linux/module.h>
  13#include <linux/tty.h>
  14#include <linux/namei.h>
  15#include <linux/backing-dev.h>
  16#include <linux/capability.h>
  17#include <linux/securebits.h>
  18#include <linux/security.h>
  19#include <linux/mount.h>
  20#include <linux/fcntl.h>
  21#include <linux/slab.h>
  22#include <asm/uaccess.h>
  23#include <linux/fs.h>
  24#include <linux/personality.h>
  25#include <linux/pagemap.h>
  26#include <linux/syscalls.h>
  27#include <linux/rcupdate.h>
  28#include <linux/audit.h>
  29#include <linux/falloc.h>
  30#include <linux/fs_struct.h>
  31#include <linux/ima.h>
  32#include <linux/dnotify.h>
  33#include <linux/compat.h>
  34
  35#include "internal.h"
  36
  37int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs,
  38	struct file *filp)
  39{
  40	int ret;
  41	struct iattr newattrs;
  42
  43	/* Not pretty: "inode->i_size" shouldn't really be signed. But it is. */
  44	if (length < 0)
  45		return -EINVAL;
  46
  47	newattrs.ia_size = length;
  48	newattrs.ia_valid = ATTR_SIZE | time_attrs;
  49	if (filp) {
  50		newattrs.ia_file = filp;
  51		newattrs.ia_valid |= ATTR_FILE;
  52	}
  53
  54	/* Remove suid, sgid, and file capabilities on truncate too */
  55	ret = dentry_needs_remove_privs(dentry);
  56	if (ret < 0)
  57		return ret;
  58	if (ret)
  59		newattrs.ia_valid |= ret | ATTR_FORCE;
  60
  61	inode_lock(dentry->d_inode);
  62	/* Note any delegations or leases have already been broken: */
  63	ret = notify_change(dentry, &newattrs, NULL);
  64	inode_unlock(dentry->d_inode);
  65	return ret;
  66}
  67
  68long vfs_truncate(struct path *path, loff_t length)
  69{
  70	struct inode *inode;
  71	long error;
  72
  73	inode = path->dentry->d_inode;
  74
  75	/* For directories it's -EISDIR, for other non-regulars - -EINVAL */
  76	if (S_ISDIR(inode->i_mode))
  77		return -EISDIR;
  78	if (!S_ISREG(inode->i_mode))
  79		return -EINVAL;
  80
  81	error = mnt_want_write(path->mnt);
  82	if (error)
  83		goto out;
  84
  85	error = inode_permission(inode, MAY_WRITE);
  86	if (error)
  87		goto mnt_drop_write_and_out;
  88
  89	error = -EPERM;
  90	if (IS_APPEND(inode))
  91		goto mnt_drop_write_and_out;
  92
  93	error = get_write_access(inode);
  94	if (error)
  95		goto mnt_drop_write_and_out;
  96
  97	/*
  98	 * Make sure that there are no leases.  get_write_access() protects
  99	 * against the truncate racing with a lease-granting setlease().
 100	 */
 101	error = break_lease(inode, O_WRONLY);
 102	if (error)
 103		goto put_write_and_out;
 104
 105	error = locks_verify_truncate(inode, NULL, length);
 106	if (!error)
 107		error = security_path_truncate(path);
 108	if (!error)
 109		error = do_truncate(path->dentry, length, 0, NULL);
 110
 111put_write_and_out:
 112	put_write_access(inode);
 113mnt_drop_write_and_out:
 114	mnt_drop_write(path->mnt);
 115out:
 116	return error;
 117}
 118EXPORT_SYMBOL_GPL(vfs_truncate);
 119
 120static long do_sys_truncate(const char __user *pathname, loff_t length)
 121{
 122	unsigned int lookup_flags = LOOKUP_FOLLOW;
 123	struct path path;
 124	int error;
 125
 126	if (length < 0)	/* sorry, but loff_t says... */
 127		return -EINVAL;
 128
 129retry:
 130	error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
 131	if (!error) {
 132		error = vfs_truncate(&path, length);
 133		path_put(&path);
 134	}
 135	if (retry_estale(error, lookup_flags)) {
 136		lookup_flags |= LOOKUP_REVAL;
 137		goto retry;
 138	}
 139	return error;
 140}
 141
 142SYSCALL_DEFINE2(truncate, const char __user *, path, long, length)
 143{
 144	return do_sys_truncate(path, length);
 145}
 146
 147#ifdef CONFIG_COMPAT
 148COMPAT_SYSCALL_DEFINE2(truncate, const char __user *, path, compat_off_t, length)
 149{
 150	return do_sys_truncate(path, length);
 151}
 152#endif
 153
 154static long do_sys_ftruncate(unsigned int fd, loff_t length, int small)
 155{
 156	struct inode *inode;
 157	struct dentry *dentry;
 158	struct fd f;
 159	int error;
 160
 161	error = -EINVAL;
 162	if (length < 0)
 163		goto out;
 164	error = -EBADF;
 165	f = fdget(fd);
 166	if (!f.file)
 167		goto out;
 168
 169	/* explicitly opened as large or we are on 64-bit box */
 170	if (f.file->f_flags & O_LARGEFILE)
 171		small = 0;
 172
 173	dentry = f.file->f_path.dentry;
 174	inode = dentry->d_inode;
 175	error = -EINVAL;
 176	if (!S_ISREG(inode->i_mode) || !(f.file->f_mode & FMODE_WRITE))
 177		goto out_putf;
 178
 179	error = -EINVAL;
 180	/* Cannot ftruncate over 2^31 bytes without large file support */
 181	if (small && length > MAX_NON_LFS)
 182		goto out_putf;
 183
 184	error = -EPERM;
 185	if (IS_APPEND(inode))
 
 186		goto out_putf;
 187
 188	sb_start_write(inode->i_sb);
 189	error = locks_verify_truncate(inode, f.file, length);
 190	if (!error)
 191		error = security_path_truncate(&f.file->f_path);
 192	if (!error)
 193		error = do_truncate(dentry, length, ATTR_MTIME|ATTR_CTIME, f.file);
 194	sb_end_write(inode->i_sb);
 195out_putf:
 196	fdput(f);
 197out:
 198	return error;
 199}
 200
 201SYSCALL_DEFINE2(ftruncate, unsigned int, fd, unsigned long, length)
 202{
 203	return do_sys_ftruncate(fd, length, 1);
 204}
 205
 206#ifdef CONFIG_COMPAT
 207COMPAT_SYSCALL_DEFINE2(ftruncate, unsigned int, fd, compat_ulong_t, length)
 208{
 209	return do_sys_ftruncate(fd, length, 1);
 210}
 211#endif
 212
 213/* LFS versions of truncate are only needed on 32 bit machines */
 214#if BITS_PER_LONG == 32
 215SYSCALL_DEFINE2(truncate64, const char __user *, path, loff_t, length)
 216{
 217	return do_sys_truncate(path, length);
 218}
 219
 220SYSCALL_DEFINE2(ftruncate64, unsigned int, fd, loff_t, length)
 221{
 222	return do_sys_ftruncate(fd, length, 0);
 223}
 224#endif /* BITS_PER_LONG == 32 */
 225
 226
 227int vfs_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
 228{
 229	struct inode *inode = file_inode(file);
 230	long ret;
 231
 232	if (offset < 0 || len <= 0)
 233		return -EINVAL;
 234
 235	/* Return error if mode is not supported */
 236	if (mode & ~FALLOC_FL_SUPPORTED_MASK)
 237		return -EOPNOTSUPP;
 238
 239	/* Punch hole and zero range are mutually exclusive */
 240	if ((mode & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE)) ==
 241	    (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE))
 242		return -EOPNOTSUPP;
 243
 244	/* Punch hole must have keep size set */
 245	if ((mode & FALLOC_FL_PUNCH_HOLE) &&
 246	    !(mode & FALLOC_FL_KEEP_SIZE))
 247		return -EOPNOTSUPP;
 248
 249	/* Collapse range should only be used exclusively. */
 250	if ((mode & FALLOC_FL_COLLAPSE_RANGE) &&
 251	    (mode & ~FALLOC_FL_COLLAPSE_RANGE))
 252		return -EINVAL;
 253
 254	/* Insert range should only be used exclusively. */
 255	if ((mode & FALLOC_FL_INSERT_RANGE) &&
 256	    (mode & ~FALLOC_FL_INSERT_RANGE))
 257		return -EINVAL;
 258
 
 
 
 
 
 259	if (!(file->f_mode & FMODE_WRITE))
 260		return -EBADF;
 261
 262	/*
 263	 * We can only allow pure fallocate on append only files
 264	 */
 265	if ((mode & ~FALLOC_FL_KEEP_SIZE) && IS_APPEND(inode))
 266		return -EPERM;
 267
 268	if (IS_IMMUTABLE(inode))
 269		return -EPERM;
 270
 271	/*
 272	 * We cannot allow any fallocate operation on an active swapfile
 273	 */
 274	if (IS_SWAPFILE(inode))
 275		return -ETXTBSY;
 276
 277	/*
 278	 * Revalidate the write permissions, in case security policy has
 279	 * changed since the files were opened.
 280	 */
 281	ret = security_file_permission(file, MAY_WRITE);
 282	if (ret)
 283		return ret;
 284
 285	if (S_ISFIFO(inode->i_mode))
 286		return -ESPIPE;
 287
 288	/*
 289	 * Let individual file system decide if it supports preallocation
 290	 * for directories or not.
 291	 */
 292	if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode))
 293		return -ENODEV;
 294
 295	/* Check for wrap through zero too */
 296	if (((offset + len) > inode->i_sb->s_maxbytes) || ((offset + len) < 0))
 297		return -EFBIG;
 298
 299	if (!file->f_op->fallocate)
 300		return -EOPNOTSUPP;
 301
 302	sb_start_write(inode->i_sb);
 303	ret = file->f_op->fallocate(file, mode, offset, len);
 304
 305	/*
 306	 * Create inotify and fanotify events.
 307	 *
 308	 * To keep the logic simple always create events if fallocate succeeds.
 309	 * This implies that events are even created if the file size remains
 310	 * unchanged, e.g. when using flag FALLOC_FL_KEEP_SIZE.
 311	 */
 312	if (ret == 0)
 313		fsnotify_modify(file);
 314
 315	sb_end_write(inode->i_sb);
 316	return ret;
 317}
 318EXPORT_SYMBOL_GPL(vfs_fallocate);
 319
 320SYSCALL_DEFINE4(fallocate, int, fd, int, mode, loff_t, offset, loff_t, len)
 321{
 322	struct fd f = fdget(fd);
 323	int error = -EBADF;
 324
 325	if (f.file) {
 326		error = vfs_fallocate(f.file, mode, offset, len);
 327		fdput(f);
 328	}
 329	return error;
 330}
 331
 
 
 
 
 
 332/*
 333 * access() needs to use the real uid/gid, not the effective uid/gid.
 334 * We do this by temporarily clearing all FS-related capabilities and
 335 * switching the fsuid/fsgid around to the real ones.
 336 */
 337SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode)
 338{
 339	const struct cred *old_cred;
 340	struct cred *override_cred;
 341	struct path path;
 342	struct inode *inode;
 343	int res;
 344	unsigned int lookup_flags = LOOKUP_FOLLOW;
 345
 346	if (mode & ~S_IRWXO)	/* where's F_OK, X_OK, W_OK, R_OK? */
 347		return -EINVAL;
 348
 349	override_cred = prepare_creds();
 350	if (!override_cred)
 351		return -ENOMEM;
 352
 353	override_cred->fsuid = override_cred->uid;
 354	override_cred->fsgid = override_cred->gid;
 355
 356	if (!issecure(SECURE_NO_SETUID_FIXUP)) {
 357		/* Clear the capabilities if we switch to a non-root user */
 358		kuid_t root_uid = make_kuid(override_cred->user_ns, 0);
 359		if (!uid_eq(override_cred->uid, root_uid))
 360			cap_clear(override_cred->cap_effective);
 361		else
 362			override_cred->cap_effective =
 363				override_cred->cap_permitted;
 364	}
 365
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 366	old_cred = override_creds(override_cred);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 367retry:
 368	res = user_path_at(dfd, filename, lookup_flags, &path);
 369	if (res)
 370		goto out;
 371
 372	inode = d_backing_inode(path.dentry);
 373
 374	if ((mode & MAY_EXEC) && S_ISREG(inode->i_mode)) {
 375		/*
 376		 * MAY_EXEC on regular files is denied if the fs is mounted
 377		 * with the "noexec" flag.
 378		 */
 379		res = -EACCES;
 380		if (path_noexec(&path))
 381			goto out_path_release;
 382	}
 383
 384	res = inode_permission(inode, mode | MAY_ACCESS);
 385	/* SuS v2 requires we report a read only fs too */
 386	if (res || !(mode & S_IWOTH) || special_file(inode->i_mode))
 387		goto out_path_release;
 388	/*
 389	 * This is a rare case where using __mnt_is_readonly()
 390	 * is OK without a mnt_want/drop_write() pair.  Since
 391	 * no actual write to the fs is performed here, we do
 392	 * not need to telegraph to that to anyone.
 393	 *
 394	 * By doing this, we accept that this access is
 395	 * inherently racy and know that the fs may change
 396	 * state before we even see this result.
 397	 */
 398	if (__mnt_is_readonly(path.mnt))
 399		res = -EROFS;
 400
 401out_path_release:
 402	path_put(&path);
 403	if (retry_estale(res, lookup_flags)) {
 404		lookup_flags |= LOOKUP_REVAL;
 405		goto retry;
 406	}
 407out:
 408	revert_creds(old_cred);
 409	put_cred(override_cred);
 
 410	return res;
 411}
 412
 
 
 
 
 
 
 
 
 
 
 
 413SYSCALL_DEFINE2(access, const char __user *, filename, int, mode)
 414{
 415	return sys_faccessat(AT_FDCWD, filename, mode);
 416}
 417
 418SYSCALL_DEFINE1(chdir, const char __user *, filename)
 419{
 420	struct path path;
 421	int error;
 422	unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
 423retry:
 424	error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
 425	if (error)
 426		goto out;
 427
 428	error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
 429	if (error)
 430		goto dput_and_out;
 431
 432	set_fs_pwd(current->fs, &path);
 433
 434dput_and_out:
 435	path_put(&path);
 436	if (retry_estale(error, lookup_flags)) {
 437		lookup_flags |= LOOKUP_REVAL;
 438		goto retry;
 439	}
 440out:
 441	return error;
 442}
 443
 444SYSCALL_DEFINE1(fchdir, unsigned int, fd)
 445{
 446	struct fd f = fdget_raw(fd);
 447	struct inode *inode;
 448	int error = -EBADF;
 449
 450	error = -EBADF;
 451	if (!f.file)
 452		goto out;
 453
 454	inode = file_inode(f.file);
 455
 456	error = -ENOTDIR;
 457	if (!S_ISDIR(inode->i_mode))
 458		goto out_putf;
 459
 460	error = inode_permission(inode, MAY_EXEC | MAY_CHDIR);
 461	if (!error)
 462		set_fs_pwd(current->fs, &f.file->f_path);
 463out_putf:
 464	fdput(f);
 465out:
 466	return error;
 467}
 468
 469SYSCALL_DEFINE1(chroot, const char __user *, filename)
 470{
 471	struct path path;
 472	int error;
 473	unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
 474retry:
 475	error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
 476	if (error)
 477		goto out;
 478
 479	error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
 480	if (error)
 481		goto dput_and_out;
 482
 483	error = -EPERM;
 484	if (!ns_capable(current_user_ns(), CAP_SYS_CHROOT))
 485		goto dput_and_out;
 486	error = security_path_chroot(&path);
 487	if (error)
 488		goto dput_and_out;
 489
 490	set_fs_root(current->fs, &path);
 491	error = 0;
 492dput_and_out:
 493	path_put(&path);
 494	if (retry_estale(error, lookup_flags)) {
 495		lookup_flags |= LOOKUP_REVAL;
 496		goto retry;
 497	}
 498out:
 499	return error;
 500}
 501
 502static int chmod_common(struct path *path, umode_t mode)
 503{
 504	struct inode *inode = path->dentry->d_inode;
 505	struct inode *delegated_inode = NULL;
 506	struct iattr newattrs;
 507	int error;
 508
 509	error = mnt_want_write(path->mnt);
 510	if (error)
 511		return error;
 512retry_deleg:
 513	inode_lock(inode);
 514	error = security_path_chmod(path, mode);
 515	if (error)
 516		goto out_unlock;
 517	newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
 518	newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
 519	error = notify_change(path->dentry, &newattrs, &delegated_inode);
 520out_unlock:
 521	inode_unlock(inode);
 522	if (delegated_inode) {
 523		error = break_deleg_wait(&delegated_inode);
 524		if (!error)
 525			goto retry_deleg;
 526	}
 527	mnt_drop_write(path->mnt);
 528	return error;
 529}
 530
 
 
 
 
 
 
 531SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode)
 532{
 533	struct fd f = fdget(fd);
 534	int err = -EBADF;
 535
 536	if (f.file) {
 537		audit_file(f.file);
 538		err = chmod_common(&f.file->f_path, mode);
 539		fdput(f);
 540	}
 541	return err;
 542}
 543
 544SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename, umode_t, mode)
 545{
 546	struct path path;
 547	int error;
 548	unsigned int lookup_flags = LOOKUP_FOLLOW;
 549retry:
 550	error = user_path_at(dfd, filename, lookup_flags, &path);
 551	if (!error) {
 552		error = chmod_common(&path, mode);
 553		path_put(&path);
 554		if (retry_estale(error, lookup_flags)) {
 555			lookup_flags |= LOOKUP_REVAL;
 556			goto retry;
 557		}
 558	}
 559	return error;
 560}
 561
 
 
 
 
 
 
 562SYSCALL_DEFINE2(chmod, const char __user *, filename, umode_t, mode)
 563{
 564	return sys_fchmodat(AT_FDCWD, filename, mode);
 565}
 566
 567static int chown_common(struct path *path, uid_t user, gid_t group)
 568{
 569	struct inode *inode = path->dentry->d_inode;
 570	struct inode *delegated_inode = NULL;
 571	int error;
 572	struct iattr newattrs;
 573	kuid_t uid;
 574	kgid_t gid;
 575
 576	uid = make_kuid(current_user_ns(), user);
 577	gid = make_kgid(current_user_ns(), group);
 578
 579retry_deleg:
 580	newattrs.ia_valid =  ATTR_CTIME;
 581	if (user != (uid_t) -1) {
 582		if (!uid_valid(uid))
 583			return -EINVAL;
 584		newattrs.ia_valid |= ATTR_UID;
 585		newattrs.ia_uid = uid;
 586	}
 587	if (group != (gid_t) -1) {
 588		if (!gid_valid(gid))
 589			return -EINVAL;
 590		newattrs.ia_valid |= ATTR_GID;
 591		newattrs.ia_gid = gid;
 592	}
 593	if (!S_ISDIR(inode->i_mode))
 594		newattrs.ia_valid |=
 595			ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_KILL_PRIV;
 596	inode_lock(inode);
 597	error = security_path_chown(path, uid, gid);
 598	if (!error)
 599		error = notify_change(path->dentry, &newattrs, &delegated_inode);
 600	inode_unlock(inode);
 601	if (delegated_inode) {
 602		error = break_deleg_wait(&delegated_inode);
 603		if (!error)
 604			goto retry_deleg;
 605	}
 606	return error;
 607}
 608
 609SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user,
 610		gid_t, group, int, flag)
 611{
 612	struct path path;
 613	int error = -EINVAL;
 614	int lookup_flags;
 615
 616	if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
 617		goto out;
 618
 619	lookup_flags = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
 620	if (flag & AT_EMPTY_PATH)
 621		lookup_flags |= LOOKUP_EMPTY;
 622retry:
 623	error = user_path_at(dfd, filename, lookup_flags, &path);
 624	if (error)
 625		goto out;
 626	error = mnt_want_write(path.mnt);
 627	if (error)
 628		goto out_release;
 629	error = chown_common(&path, user, group);
 630	mnt_drop_write(path.mnt);
 631out_release:
 632	path_put(&path);
 633	if (retry_estale(error, lookup_flags)) {
 634		lookup_flags |= LOOKUP_REVAL;
 635		goto retry;
 636	}
 637out:
 638	return error;
 639}
 640
 
 
 
 
 
 
 641SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group)
 642{
 643	return sys_fchownat(AT_FDCWD, filename, user, group, 0);
 644}
 645
 646SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group)
 647{
 648	return sys_fchownat(AT_FDCWD, filename, user, group,
 649			    AT_SYMLINK_NOFOLLOW);
 650}
 651
 652SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group)
 653{
 654	struct fd f = fdget(fd);
 655	int error = -EBADF;
 656
 657	if (!f.file)
 658		goto out;
 659
 660	error = mnt_want_write_file(f.file);
 661	if (error)
 662		goto out_fput;
 663	audit_file(f.file);
 664	error = chown_common(&f.file->f_path, user, group);
 665	mnt_drop_write_file(f.file);
 666out_fput:
 667	fdput(f);
 668out:
 669	return error;
 670}
 671
 672int open_check_o_direct(struct file *f)
 673{
 674	/* NB: we're sure to have correct a_ops only after f_op->open */
 675	if (f->f_flags & O_DIRECT) {
 676		if (!f->f_mapping->a_ops || !f->f_mapping->a_ops->direct_IO)
 677			return -EINVAL;
 
 
 678	}
 679	return 0;
 
 
 
 
 
 680}
 681
 682static int do_dentry_open(struct file *f,
 683			  struct inode *inode,
 684			  int (*open)(struct inode *, struct file *),
 685			  const struct cred *cred)
 686{
 687	static const struct file_operations empty_fops = {};
 688	int error;
 689
 690	f->f_mode = OPEN_FMODE(f->f_flags) | FMODE_LSEEK |
 691				FMODE_PREAD | FMODE_PWRITE;
 692
 693	path_get(&f->f_path);
 694	f->f_inode = inode;
 695	f->f_mapping = inode->i_mapping;
 
 
 696
 697	if (unlikely(f->f_flags & O_PATH)) {
 698		f->f_mode = FMODE_PATH;
 699		f->f_op = &empty_fops;
 700		return 0;
 701	}
 702
 703	if (f->f_mode & FMODE_WRITE && !special_file(inode->i_mode)) {
 704		error = get_write_access(inode);
 705		if (unlikely(error))
 706			goto cleanup_file;
 707		error = __mnt_want_write(f->f_path.mnt);
 708		if (unlikely(error)) {
 709			put_write_access(inode);
 710			goto cleanup_file;
 711		}
 712		f->f_mode |= FMODE_WRITER;
 713	}
 714
 715	/* POSIX.1-2008/SUSv4 Section XSI 2.9.7 */
 716	if (S_ISREG(inode->i_mode))
 717		f->f_mode |= FMODE_ATOMIC_POS;
 718
 719	f->f_op = fops_get(inode->i_fop);
 720	if (unlikely(WARN_ON(!f->f_op))) {
 721		error = -ENODEV;
 722		goto cleanup_all;
 723	}
 724
 725	error = security_file_open(f, cred);
 726	if (error)
 727		goto cleanup_all;
 728
 729	error = break_lease(inode, f->f_flags);
 730	if (error)
 731		goto cleanup_all;
 732
 
 
 733	if (!open)
 734		open = f->f_op->open;
 735	if (open) {
 736		error = open(inode, f);
 737		if (error)
 738			goto cleanup_all;
 739	}
 
 740	if ((f->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
 741		i_readcount_inc(inode);
 742	if ((f->f_mode & FMODE_READ) &&
 743	     likely(f->f_op->read || f->f_op->read_iter))
 744		f->f_mode |= FMODE_CAN_READ;
 745	if ((f->f_mode & FMODE_WRITE) &&
 746	     likely(f->f_op->write || f->f_op->write_iter))
 747		f->f_mode |= FMODE_CAN_WRITE;
 748
 
 749	f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
 750
 751	file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);
 752
 
 
 
 
 
 
 
 
 
 
 
 
 
 753	return 0;
 754
 755cleanup_all:
 
 
 756	fops_put(f->f_op);
 757	if (f->f_mode & FMODE_WRITER) {
 758		put_write_access(inode);
 759		__mnt_drop_write(f->f_path.mnt);
 760	}
 761cleanup_file:
 762	path_put(&f->f_path);
 763	f->f_path.mnt = NULL;
 764	f->f_path.dentry = NULL;
 765	f->f_inode = NULL;
 766	return error;
 767}
 768
 769/**
 770 * finish_open - finish opening a file
 771 * @file: file pointer
 772 * @dentry: pointer to dentry
 773 * @open: open callback
 774 * @opened: state of open
 775 *
 776 * This can be used to finish opening a file passed to i_op->atomic_open().
 777 *
 778 * If the open callback is set to NULL, then the standard f_op->open()
 779 * filesystem callback is substituted.
 780 *
 781 * NB: the dentry reference is _not_ consumed.  If, for example, the dentry is
 782 * the return value of d_splice_alias(), then the caller needs to perform dput()
 783 * on it after finish_open().
 784 *
 785 * On successful return @file is a fully instantiated open file.  After this, if
 786 * an error occurs in ->atomic_open(), it needs to clean up with fput().
 787 *
 788 * Returns zero on success or -errno if the open failed.
 789 */
 790int finish_open(struct file *file, struct dentry *dentry,
 791		int (*open)(struct inode *, struct file *),
 792		int *opened)
 793{
 794	int error;
 795	BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */
 796
 797	file->f_path.dentry = dentry;
 798	error = do_dentry_open(file, d_backing_inode(dentry), open,
 799			       current_cred());
 800	if (!error)
 801		*opened |= FILE_OPENED;
 802
 803	return error;
 804}
 805EXPORT_SYMBOL(finish_open);
 806
 807/**
 808 * finish_no_open - finish ->atomic_open() without opening the file
 809 *
 810 * @file: file pointer
 811 * @dentry: dentry or NULL (as returned from ->lookup())
 812 *
 813 * This can be used to set the result of a successful lookup in ->atomic_open().
 814 *
 815 * NB: unlike finish_open() this function does consume the dentry reference and
 816 * the caller need not dput() it.
 817 *
 818 * Returns "1" which must be the return value of ->atomic_open() after having
 819 * called this function.
 820 */
 821int finish_no_open(struct file *file, struct dentry *dentry)
 822{
 823	file->f_path.dentry = dentry;
 824	return 1;
 825}
 826EXPORT_SYMBOL(finish_no_open);
 827
 828char *file_path(struct file *filp, char *buf, int buflen)
 829{
 830	return d_path(&filp->f_path, buf, buflen);
 831}
 832EXPORT_SYMBOL(file_path);
 833
 834/**
 835 * vfs_open - open the file at the given path
 836 * @path: path to open
 837 * @file: newly allocated file with f_flag initialized
 838 * @cred: credentials to use
 839 */
 840int vfs_open(const struct path *path, struct file *file,
 841	     const struct cred *cred)
 842{
 843	struct inode *inode = vfs_select_inode(path->dentry, file->f_flags);
 844
 845	if (IS_ERR(inode))
 846		return PTR_ERR(inode);
 847
 848	file->f_path = *path;
 849	return do_dentry_open(file, inode, NULL, cred);
 850}
 851
 852struct file *dentry_open(const struct path *path, int flags,
 853			 const struct cred *cred)
 854{
 855	int error;
 856	struct file *f;
 857
 858	validate_creds(cred);
 859
 860	/* We must always pass in a valid mount pointer. */
 861	BUG_ON(!path->mnt);
 862
 863	f = get_empty_filp();
 864	if (!IS_ERR(f)) {
 865		f->f_flags = flags;
 866		error = vfs_open(path, f, cred);
 867		if (!error) {
 868			/* from now on we need fput() to dispose of f */
 869			error = open_check_o_direct(f);
 870			if (error) {
 871				fput(f);
 872				f = ERR_PTR(error);
 873			}
 874		} else { 
 875			put_filp(f);
 876			f = ERR_PTR(error);
 877		}
 878	}
 879	return f;
 880}
 881EXPORT_SYMBOL(dentry_open);
 882
 883static inline int build_open_flags(int flags, umode_t mode, struct open_flags *op)
 
 884{
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 885	int lookup_flags = 0;
 886	int acc_mode = ACC_MODE(flags);
 887
 888	if (flags & (O_CREAT | __O_TMPFILE))
 889		op->mode = (mode & S_IALLUGO) | S_IFREG;
 890	else
 891		op->mode = 0;
 892
 893	/* Must never be set by userspace */
 894	flags &= ~FMODE_NONOTIFY & ~O_CLOEXEC;
 895
 896	/*
 897	 * O_SYNC is implemented as __O_SYNC|O_DSYNC.  As many places only
 898	 * check for O_DSYNC if the need any syncing at all we enforce it's
 899	 * always set instead of having to deal with possibly weird behaviour
 900	 * for malicious applications setting only __O_SYNC.
 901	 */
 902	if (flags & __O_SYNC)
 903		flags |= O_DSYNC;
 
 
 904
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 905	if (flags & __O_TMPFILE) {
 906		if ((flags & O_TMPFILE_MASK) != O_TMPFILE)
 907			return -EINVAL;
 908		if (!(acc_mode & MAY_WRITE))
 909			return -EINVAL;
 910	} else if (flags & O_PATH) {
 911		/*
 912		 * If we have O_PATH in the open flag. Then we
 913		 * cannot have anything other than the below set of flags
 914		 */
 915		flags &= O_DIRECTORY | O_NOFOLLOW | O_PATH;
 916		acc_mode = 0;
 917	}
 918
 
 
 
 
 
 
 
 
 
 919	op->open_flag = flags;
 920
 921	/* O_TRUNC implies we need access checks for write permissions */
 922	if (flags & O_TRUNC)
 923		acc_mode |= MAY_WRITE;
 924
 925	/* Allow the LSM permission hook to distinguish append
 926	   access from general write access. */
 927	if (flags & O_APPEND)
 928		acc_mode |= MAY_APPEND;
 929
 930	op->acc_mode = acc_mode;
 931
 932	op->intent = flags & O_PATH ? 0 : LOOKUP_OPEN;
 933
 934	if (flags & O_CREAT) {
 935		op->intent |= LOOKUP_CREATE;
 936		if (flags & O_EXCL)
 937			op->intent |= LOOKUP_EXCL;
 
 
 938	}
 939
 940	if (flags & O_DIRECTORY)
 941		lookup_flags |= LOOKUP_DIRECTORY;
 942	if (!(flags & O_NOFOLLOW))
 943		lookup_flags |= LOOKUP_FOLLOW;
 
 
 
 
 
 
 
 
 
 
 
 
 944	op->lookup_flags = lookup_flags;
 945	return 0;
 946}
 947
 948/**
 949 * file_open_name - open file and return file pointer
 950 *
 951 * @name:	struct filename containing path to open
 952 * @flags:	open flags as per the open(2) second argument
 953 * @mode:	mode for the new file if O_CREAT is set, else ignored
 954 *
 955 * This is the helper to open a file from kernelspace if you really
 956 * have to.  But in generally you should not do this, so please move
 957 * along, nothing to see here..
 958 */
 959struct file *file_open_name(struct filename *name, int flags, umode_t mode)
 960{
 961	struct open_flags op;
 962	int err = build_open_flags(flags, mode, &op);
 963	return err ? ERR_PTR(err) : do_filp_open(AT_FDCWD, name, &op);
 
 
 
 964}
 965
 966/**
 967 * filp_open - open file and return file pointer
 968 *
 969 * @filename:	path to open
 970 * @flags:	open flags as per the open(2) second argument
 971 * @mode:	mode for the new file if O_CREAT is set, else ignored
 972 *
 973 * This is the helper to open a file from kernelspace if you really
 974 * have to.  But in generally you should not do this, so please move
 975 * along, nothing to see here..
 976 */
 977struct file *filp_open(const char *filename, int flags, umode_t mode)
 978{
 979	struct filename *name = getname_kernel(filename);
 980	struct file *file = ERR_CAST(name);
 981	
 982	if (!IS_ERR(name)) {
 983		file = file_open_name(name, flags, mode);
 984		putname(name);
 985	}
 986	return file;
 987}
 988EXPORT_SYMBOL(filp_open);
 989
 990struct file *file_open_root(struct dentry *dentry, struct vfsmount *mnt,
 991			    const char *filename, int flags, umode_t mode)
 992{
 993	struct open_flags op;
 994	int err = build_open_flags(flags, mode, &op);
 
 995	if (err)
 996		return ERR_PTR(err);
 997	return do_file_open_root(dentry, mnt, filename, &op);
 998}
 999EXPORT_SYMBOL(file_open_root);
1000
1001long do_sys_open(int dfd, const char __user *filename, int flags, umode_t mode)
 
1002{
1003	struct open_flags op;
1004	int fd = build_open_flags(flags, mode, &op);
1005	struct filename *tmp;
1006
1007	if (fd)
1008		return fd;
1009
1010	tmp = getname(filename);
1011	if (IS_ERR(tmp))
1012		return PTR_ERR(tmp);
1013
1014	fd = get_unused_fd_flags(flags);
1015	if (fd >= 0) {
1016		struct file *f = do_filp_open(dfd, tmp, &op);
1017		if (IS_ERR(f)) {
1018			put_unused_fd(fd);
1019			fd = PTR_ERR(f);
1020		} else {
1021			fsnotify_open(f);
1022			fd_install(fd, f);
1023		}
1024	}
1025	putname(tmp);
1026	return fd;
1027}
1028
 
 
 
 
 
 
 
1029SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)
1030{
1031	if (force_o_largefile())
1032		flags |= O_LARGEFILE;
1033
1034	return do_sys_open(AT_FDCWD, filename, flags, mode);
1035}
1036
1037SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags,
1038		umode_t, mode)
1039{
1040	if (force_o_largefile())
1041		flags |= O_LARGEFILE;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1042
 
 
 
 
 
 
1043	return do_sys_open(dfd, filename, flags, mode);
1044}
 
1045
1046#ifndef __alpha__
1047
1048/*
1049 * For backward compatibility?  Maybe this should be moved
1050 * into arch/i386 instead?
1051 */
1052SYSCALL_DEFINE2(creat, const char __user *, pathname, umode_t, mode)
1053{
1054	return sys_open(pathname, O_CREAT | O_WRONLY | O_TRUNC, mode);
1055}
1056
 
 
 
 
1057#endif
1058
1059/*
1060 * "id" is the POSIX thread ID. We use the
1061 * files pointer for this..
1062 */
1063int filp_close(struct file *filp, fl_owner_t id)
1064{
1065	int retval = 0;
1066
1067	if (!file_count(filp)) {
1068		printk(KERN_ERR "VFS: Close: file count is 0\n");
1069		return 0;
1070	}
1071
1072	if (filp->f_op->flush)
1073		retval = filp->f_op->flush(filp, id);
1074
1075	if (likely(!(filp->f_mode & FMODE_PATH))) {
1076		dnotify_flush(filp, id);
1077		locks_remove_posix(filp, id);
1078	}
1079	fput(filp);
1080	return retval;
1081}
1082
1083EXPORT_SYMBOL(filp_close);
1084
1085/*
1086 * Careful here! We test whether the file pointer is NULL before
1087 * releasing the fd. This ensures that one clone task can't release
1088 * an fd while another clone is opening it.
1089 */
1090SYSCALL_DEFINE1(close, unsigned int, fd)
1091{
1092	int retval = __close_fd(current->files, fd);
1093
1094	/* can't restart close syscall because file table entry was cleared */
1095	if (unlikely(retval == -ERESTARTSYS ||
1096		     retval == -ERESTARTNOINTR ||
1097		     retval == -ERESTARTNOHAND ||
1098		     retval == -ERESTART_RESTARTBLOCK))
1099		retval = -EINTR;
1100
1101	return retval;
1102}
1103EXPORT_SYMBOL(sys_close);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1104
1105/*
1106 * This routine simulates a hangup on the tty, to arrange that users
1107 * are given clean terminals at login time.
1108 */
1109SYSCALL_DEFINE0(vhangup)
1110{
1111	if (capable(CAP_SYS_TTY_CONFIG)) {
1112		tty_vhangup_self();
1113		return 0;
1114	}
1115	return -EPERM;
1116}
1117
1118/*
1119 * Called when an inode is about to be open.
1120 * We use this to disallow opening large files on 32bit systems if
1121 * the caller didn't specify O_LARGEFILE.  On 64bit systems we force
1122 * on this flag in sys_open.
1123 */
1124int generic_file_open(struct inode * inode, struct file * filp)
1125{
1126	if (!(filp->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS)
1127		return -EOVERFLOW;
1128	return 0;
1129}
1130
1131EXPORT_SYMBOL(generic_file_open);
1132
1133/*
1134 * This is used by subsystems that don't want seekable
1135 * file descriptors. The function is not supposed to ever fail, the only
1136 * reason it returns an 'int' and not 'void' is so that it can be plugged
1137 * directly into file_operations structure.
1138 */
1139int nonseekable_open(struct inode *inode, struct file *filp)
1140{
1141	filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);
1142	return 0;
1143}
1144
1145EXPORT_SYMBOL(nonseekable_open);
v5.9
   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 *  linux/fs/open.c
   4 *
   5 *  Copyright (C) 1991, 1992  Linus Torvalds
   6 */
   7
   8#include <linux/string.h>
   9#include <linux/mm.h>
  10#include <linux/file.h>
  11#include <linux/fdtable.h>
  12#include <linux/fsnotify.h>
  13#include <linux/module.h>
  14#include <linux/tty.h>
  15#include <linux/namei.h>
  16#include <linux/backing-dev.h>
  17#include <linux/capability.h>
  18#include <linux/securebits.h>
  19#include <linux/security.h>
  20#include <linux/mount.h>
  21#include <linux/fcntl.h>
  22#include <linux/slab.h>
  23#include <linux/uaccess.h>
  24#include <linux/fs.h>
  25#include <linux/personality.h>
  26#include <linux/pagemap.h>
  27#include <linux/syscalls.h>
  28#include <linux/rcupdate.h>
  29#include <linux/audit.h>
  30#include <linux/falloc.h>
  31#include <linux/fs_struct.h>
  32#include <linux/ima.h>
  33#include <linux/dnotify.h>
  34#include <linux/compat.h>
  35
  36#include "internal.h"
  37
  38int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs,
  39	struct file *filp)
  40{
  41	int ret;
  42	struct iattr newattrs;
  43
  44	/* Not pretty: "inode->i_size" shouldn't really be signed. But it is. */
  45	if (length < 0)
  46		return -EINVAL;
  47
  48	newattrs.ia_size = length;
  49	newattrs.ia_valid = ATTR_SIZE | time_attrs;
  50	if (filp) {
  51		newattrs.ia_file = filp;
  52		newattrs.ia_valid |= ATTR_FILE;
  53	}
  54
  55	/* Remove suid, sgid, and file capabilities on truncate too */
  56	ret = dentry_needs_remove_privs(dentry);
  57	if (ret < 0)
  58		return ret;
  59	if (ret)
  60		newattrs.ia_valid |= ret | ATTR_FORCE;
  61
  62	inode_lock(dentry->d_inode);
  63	/* Note any delegations or leases have already been broken: */
  64	ret = notify_change(dentry, &newattrs, NULL);
  65	inode_unlock(dentry->d_inode);
  66	return ret;
  67}
  68
  69long vfs_truncate(const struct path *path, loff_t length)
  70{
  71	struct inode *inode;
  72	long error;
  73
  74	inode = path->dentry->d_inode;
  75
  76	/* For directories it's -EISDIR, for other non-regulars - -EINVAL */
  77	if (S_ISDIR(inode->i_mode))
  78		return -EISDIR;
  79	if (!S_ISREG(inode->i_mode))
  80		return -EINVAL;
  81
  82	error = mnt_want_write(path->mnt);
  83	if (error)
  84		goto out;
  85
  86	error = inode_permission(inode, MAY_WRITE);
  87	if (error)
  88		goto mnt_drop_write_and_out;
  89
  90	error = -EPERM;
  91	if (IS_APPEND(inode))
  92		goto mnt_drop_write_and_out;
  93
  94	error = get_write_access(inode);
  95	if (error)
  96		goto mnt_drop_write_and_out;
  97
  98	/*
  99	 * Make sure that there are no leases.  get_write_access() protects
 100	 * against the truncate racing with a lease-granting setlease().
 101	 */
 102	error = break_lease(inode, O_WRONLY);
 103	if (error)
 104		goto put_write_and_out;
 105
 106	error = locks_verify_truncate(inode, NULL, length);
 107	if (!error)
 108		error = security_path_truncate(path);
 109	if (!error)
 110		error = do_truncate(path->dentry, length, 0, NULL);
 111
 112put_write_and_out:
 113	put_write_access(inode);
 114mnt_drop_write_and_out:
 115	mnt_drop_write(path->mnt);
 116out:
 117	return error;
 118}
 119EXPORT_SYMBOL_GPL(vfs_truncate);
 120
 121long do_sys_truncate(const char __user *pathname, loff_t length)
 122{
 123	unsigned int lookup_flags = LOOKUP_FOLLOW;
 124	struct path path;
 125	int error;
 126
 127	if (length < 0)	/* sorry, but loff_t says... */
 128		return -EINVAL;
 129
 130retry:
 131	error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
 132	if (!error) {
 133		error = vfs_truncate(&path, length);
 134		path_put(&path);
 135	}
 136	if (retry_estale(error, lookup_flags)) {
 137		lookup_flags |= LOOKUP_REVAL;
 138		goto retry;
 139	}
 140	return error;
 141}
 142
 143SYSCALL_DEFINE2(truncate, const char __user *, path, long, length)
 144{
 145	return do_sys_truncate(path, length);
 146}
 147
 148#ifdef CONFIG_COMPAT
 149COMPAT_SYSCALL_DEFINE2(truncate, const char __user *, path, compat_off_t, length)
 150{
 151	return do_sys_truncate(path, length);
 152}
 153#endif
 154
 155long do_sys_ftruncate(unsigned int fd, loff_t length, int small)
 156{
 157	struct inode *inode;
 158	struct dentry *dentry;
 159	struct fd f;
 160	int error;
 161
 162	error = -EINVAL;
 163	if (length < 0)
 164		goto out;
 165	error = -EBADF;
 166	f = fdget(fd);
 167	if (!f.file)
 168		goto out;
 169
 170	/* explicitly opened as large or we are on 64-bit box */
 171	if (f.file->f_flags & O_LARGEFILE)
 172		small = 0;
 173
 174	dentry = f.file->f_path.dentry;
 175	inode = dentry->d_inode;
 176	error = -EINVAL;
 177	if (!S_ISREG(inode->i_mode) || !(f.file->f_mode & FMODE_WRITE))
 178		goto out_putf;
 179
 180	error = -EINVAL;
 181	/* Cannot ftruncate over 2^31 bytes without large file support */
 182	if (small && length > MAX_NON_LFS)
 183		goto out_putf;
 184
 185	error = -EPERM;
 186	/* Check IS_APPEND on real upper inode */
 187	if (IS_APPEND(file_inode(f.file)))
 188		goto out_putf;
 189
 190	sb_start_write(inode->i_sb);
 191	error = locks_verify_truncate(inode, f.file, length);
 192	if (!error)
 193		error = security_path_truncate(&f.file->f_path);
 194	if (!error)
 195		error = do_truncate(dentry, length, ATTR_MTIME|ATTR_CTIME, f.file);
 196	sb_end_write(inode->i_sb);
 197out_putf:
 198	fdput(f);
 199out:
 200	return error;
 201}
 202
 203SYSCALL_DEFINE2(ftruncate, unsigned int, fd, unsigned long, length)
 204{
 205	return do_sys_ftruncate(fd, length, 1);
 206}
 207
 208#ifdef CONFIG_COMPAT
 209COMPAT_SYSCALL_DEFINE2(ftruncate, unsigned int, fd, compat_ulong_t, length)
 210{
 211	return do_sys_ftruncate(fd, length, 1);
 212}
 213#endif
 214
 215/* LFS versions of truncate are only needed on 32 bit machines */
 216#if BITS_PER_LONG == 32
 217SYSCALL_DEFINE2(truncate64, const char __user *, path, loff_t, length)
 218{
 219	return do_sys_truncate(path, length);
 220}
 221
 222SYSCALL_DEFINE2(ftruncate64, unsigned int, fd, loff_t, length)
 223{
 224	return do_sys_ftruncate(fd, length, 0);
 225}
 226#endif /* BITS_PER_LONG == 32 */
 227
 228
 229int vfs_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
 230{
 231	struct inode *inode = file_inode(file);
 232	long ret;
 233
 234	if (offset < 0 || len <= 0)
 235		return -EINVAL;
 236
 237	/* Return error if mode is not supported */
 238	if (mode & ~FALLOC_FL_SUPPORTED_MASK)
 239		return -EOPNOTSUPP;
 240
 241	/* Punch hole and zero range are mutually exclusive */
 242	if ((mode & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE)) ==
 243	    (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE))
 244		return -EOPNOTSUPP;
 245
 246	/* Punch hole must have keep size set */
 247	if ((mode & FALLOC_FL_PUNCH_HOLE) &&
 248	    !(mode & FALLOC_FL_KEEP_SIZE))
 249		return -EOPNOTSUPP;
 250
 251	/* Collapse range should only be used exclusively. */
 252	if ((mode & FALLOC_FL_COLLAPSE_RANGE) &&
 253	    (mode & ~FALLOC_FL_COLLAPSE_RANGE))
 254		return -EINVAL;
 255
 256	/* Insert range should only be used exclusively. */
 257	if ((mode & FALLOC_FL_INSERT_RANGE) &&
 258	    (mode & ~FALLOC_FL_INSERT_RANGE))
 259		return -EINVAL;
 260
 261	/* Unshare range should only be used with allocate mode. */
 262	if ((mode & FALLOC_FL_UNSHARE_RANGE) &&
 263	    (mode & ~(FALLOC_FL_UNSHARE_RANGE | FALLOC_FL_KEEP_SIZE)))
 264		return -EINVAL;
 265
 266	if (!(file->f_mode & FMODE_WRITE))
 267		return -EBADF;
 268
 269	/*
 270	 * We can only allow pure fallocate on append only files
 271	 */
 272	if ((mode & ~FALLOC_FL_KEEP_SIZE) && IS_APPEND(inode))
 273		return -EPERM;
 274
 275	if (IS_IMMUTABLE(inode))
 276		return -EPERM;
 277
 278	/*
 279	 * We cannot allow any fallocate operation on an active swapfile
 280	 */
 281	if (IS_SWAPFILE(inode))
 282		return -ETXTBSY;
 283
 284	/*
 285	 * Revalidate the write permissions, in case security policy has
 286	 * changed since the files were opened.
 287	 */
 288	ret = security_file_permission(file, MAY_WRITE);
 289	if (ret)
 290		return ret;
 291
 292	if (S_ISFIFO(inode->i_mode))
 293		return -ESPIPE;
 294
 295	if (S_ISDIR(inode->i_mode))
 296		return -EISDIR;
 297
 298	if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
 
 299		return -ENODEV;
 300
 301	/* Check for wrap through zero too */
 302	if (((offset + len) > inode->i_sb->s_maxbytes) || ((offset + len) < 0))
 303		return -EFBIG;
 304
 305	if (!file->f_op->fallocate)
 306		return -EOPNOTSUPP;
 307
 308	file_start_write(file);
 309	ret = file->f_op->fallocate(file, mode, offset, len);
 310
 311	/*
 312	 * Create inotify and fanotify events.
 313	 *
 314	 * To keep the logic simple always create events if fallocate succeeds.
 315	 * This implies that events are even created if the file size remains
 316	 * unchanged, e.g. when using flag FALLOC_FL_KEEP_SIZE.
 317	 */
 318	if (ret == 0)
 319		fsnotify_modify(file);
 320
 321	file_end_write(file);
 322	return ret;
 323}
 324EXPORT_SYMBOL_GPL(vfs_fallocate);
 325
 326int ksys_fallocate(int fd, int mode, loff_t offset, loff_t len)
 327{
 328	struct fd f = fdget(fd);
 329	int error = -EBADF;
 330
 331	if (f.file) {
 332		error = vfs_fallocate(f.file, mode, offset, len);
 333		fdput(f);
 334	}
 335	return error;
 336}
 337
 338SYSCALL_DEFINE4(fallocate, int, fd, int, mode, loff_t, offset, loff_t, len)
 339{
 340	return ksys_fallocate(fd, mode, offset, len);
 341}
 342
 343/*
 344 * access() needs to use the real uid/gid, not the effective uid/gid.
 345 * We do this by temporarily clearing all FS-related capabilities and
 346 * switching the fsuid/fsgid around to the real ones.
 347 */
 348static const struct cred *access_override_creds(void)
 349{
 350	const struct cred *old_cred;
 351	struct cred *override_cred;
 
 
 
 
 
 
 
 352
 353	override_cred = prepare_creds();
 354	if (!override_cred)
 355		return NULL;
 356
 357	override_cred->fsuid = override_cred->uid;
 358	override_cred->fsgid = override_cred->gid;
 359
 360	if (!issecure(SECURE_NO_SETUID_FIXUP)) {
 361		/* Clear the capabilities if we switch to a non-root user */
 362		kuid_t root_uid = make_kuid(override_cred->user_ns, 0);
 363		if (!uid_eq(override_cred->uid, root_uid))
 364			cap_clear(override_cred->cap_effective);
 365		else
 366			override_cred->cap_effective =
 367				override_cred->cap_permitted;
 368	}
 369
 370	/*
 371	 * The new set of credentials can *only* be used in
 372	 * task-synchronous circumstances, and does not need
 373	 * RCU freeing, unless somebody then takes a separate
 374	 * reference to it.
 375	 *
 376	 * NOTE! This is _only_ true because this credential
 377	 * is used purely for override_creds() that installs
 378	 * it as the subjective cred. Other threads will be
 379	 * accessing ->real_cred, not the subjective cred.
 380	 *
 381	 * If somebody _does_ make a copy of this (using the
 382	 * 'get_current_cred()' function), that will clear the
 383	 * non_rcu field, because now that other user may be
 384	 * expecting RCU freeing. But normal thread-synchronous
 385	 * cred accesses will keep things non-RCY.
 386	 */
 387	override_cred->non_rcu = 1;
 388
 389	old_cred = override_creds(override_cred);
 390
 391	/* override_cred() gets its own ref */
 392	put_cred(override_cred);
 393
 394	return old_cred;
 395}
 396
 397static long do_faccessat(int dfd, const char __user *filename, int mode, int flags)
 398{
 399	struct path path;
 400	struct inode *inode;
 401	int res;
 402	unsigned int lookup_flags = LOOKUP_FOLLOW;
 403	const struct cred *old_cred = NULL;
 404
 405	if (mode & ~S_IRWXO)	/* where's F_OK, X_OK, W_OK, R_OK? */
 406		return -EINVAL;
 407
 408	if (flags & ~(AT_EACCESS | AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH))
 409		return -EINVAL;
 410
 411	if (flags & AT_SYMLINK_NOFOLLOW)
 412		lookup_flags &= ~LOOKUP_FOLLOW;
 413	if (flags & AT_EMPTY_PATH)
 414		lookup_flags |= LOOKUP_EMPTY;
 415
 416	if (!(flags & AT_EACCESS)) {
 417		old_cred = access_override_creds();
 418		if (!old_cred)
 419			return -ENOMEM;
 420	}
 421
 422retry:
 423	res = user_path_at(dfd, filename, lookup_flags, &path);
 424	if (res)
 425		goto out;
 426
 427	inode = d_backing_inode(path.dentry);
 428
 429	if ((mode & MAY_EXEC) && S_ISREG(inode->i_mode)) {
 430		/*
 431		 * MAY_EXEC on regular files is denied if the fs is mounted
 432		 * with the "noexec" flag.
 433		 */
 434		res = -EACCES;
 435		if (path_noexec(&path))
 436			goto out_path_release;
 437	}
 438
 439	res = inode_permission(inode, mode | MAY_ACCESS);
 440	/* SuS v2 requires we report a read only fs too */
 441	if (res || !(mode & S_IWOTH) || special_file(inode->i_mode))
 442		goto out_path_release;
 443	/*
 444	 * This is a rare case where using __mnt_is_readonly()
 445	 * is OK without a mnt_want/drop_write() pair.  Since
 446	 * no actual write to the fs is performed here, we do
 447	 * not need to telegraph to that to anyone.
 448	 *
 449	 * By doing this, we accept that this access is
 450	 * inherently racy and know that the fs may change
 451	 * state before we even see this result.
 452	 */
 453	if (__mnt_is_readonly(path.mnt))
 454		res = -EROFS;
 455
 456out_path_release:
 457	path_put(&path);
 458	if (retry_estale(res, lookup_flags)) {
 459		lookup_flags |= LOOKUP_REVAL;
 460		goto retry;
 461	}
 462out:
 463	if (old_cred)
 464		revert_creds(old_cred);
 465
 466	return res;
 467}
 468
 469SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode)
 470{
 471	return do_faccessat(dfd, filename, mode, 0);
 472}
 473
 474SYSCALL_DEFINE4(faccessat2, int, dfd, const char __user *, filename, int, mode,
 475		int, flags)
 476{
 477	return do_faccessat(dfd, filename, mode, flags);
 478}
 479
 480SYSCALL_DEFINE2(access, const char __user *, filename, int, mode)
 481{
 482	return do_faccessat(AT_FDCWD, filename, mode, 0);
 483}
 484
 485SYSCALL_DEFINE1(chdir, const char __user *, filename)
 486{
 487	struct path path;
 488	int error;
 489	unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
 490retry:
 491	error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
 492	if (error)
 493		goto out;
 494
 495	error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
 496	if (error)
 497		goto dput_and_out;
 498
 499	set_fs_pwd(current->fs, &path);
 500
 501dput_and_out:
 502	path_put(&path);
 503	if (retry_estale(error, lookup_flags)) {
 504		lookup_flags |= LOOKUP_REVAL;
 505		goto retry;
 506	}
 507out:
 508	return error;
 509}
 510
 511SYSCALL_DEFINE1(fchdir, unsigned int, fd)
 512{
 513	struct fd f = fdget_raw(fd);
 514	int error;
 
 515
 516	error = -EBADF;
 517	if (!f.file)
 518		goto out;
 519
 
 
 520	error = -ENOTDIR;
 521	if (!d_can_lookup(f.file->f_path.dentry))
 522		goto out_putf;
 523
 524	error = inode_permission(file_inode(f.file), MAY_EXEC | MAY_CHDIR);
 525	if (!error)
 526		set_fs_pwd(current->fs, &f.file->f_path);
 527out_putf:
 528	fdput(f);
 529out:
 530	return error;
 531}
 532
 533SYSCALL_DEFINE1(chroot, const char __user *, filename)
 534{
 535	struct path path;
 536	int error;
 537	unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
 538retry:
 539	error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
 540	if (error)
 541		goto out;
 542
 543	error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
 544	if (error)
 545		goto dput_and_out;
 546
 547	error = -EPERM;
 548	if (!ns_capable(current_user_ns(), CAP_SYS_CHROOT))
 549		goto dput_and_out;
 550	error = security_path_chroot(&path);
 551	if (error)
 552		goto dput_and_out;
 553
 554	set_fs_root(current->fs, &path);
 555	error = 0;
 556dput_and_out:
 557	path_put(&path);
 558	if (retry_estale(error, lookup_flags)) {
 559		lookup_flags |= LOOKUP_REVAL;
 560		goto retry;
 561	}
 562out:
 563	return error;
 564}
 565
 566int chmod_common(const struct path *path, umode_t mode)
 567{
 568	struct inode *inode = path->dentry->d_inode;
 569	struct inode *delegated_inode = NULL;
 570	struct iattr newattrs;
 571	int error;
 572
 573	error = mnt_want_write(path->mnt);
 574	if (error)
 575		return error;
 576retry_deleg:
 577	inode_lock(inode);
 578	error = security_path_chmod(path, mode);
 579	if (error)
 580		goto out_unlock;
 581	newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
 582	newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
 583	error = notify_change(path->dentry, &newattrs, &delegated_inode);
 584out_unlock:
 585	inode_unlock(inode);
 586	if (delegated_inode) {
 587		error = break_deleg_wait(&delegated_inode);
 588		if (!error)
 589			goto retry_deleg;
 590	}
 591	mnt_drop_write(path->mnt);
 592	return error;
 593}
 594
 595int vfs_fchmod(struct file *file, umode_t mode)
 596{
 597	audit_file(file);
 598	return chmod_common(&file->f_path, mode);
 599}
 600
 601SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode)
 602{
 603	struct fd f = fdget(fd);
 604	int err = -EBADF;
 605
 606	if (f.file) {
 607		err = vfs_fchmod(f.file, mode);
 
 608		fdput(f);
 609	}
 610	return err;
 611}
 612
 613static int do_fchmodat(int dfd, const char __user *filename, umode_t mode)
 614{
 615	struct path path;
 616	int error;
 617	unsigned int lookup_flags = LOOKUP_FOLLOW;
 618retry:
 619	error = user_path_at(dfd, filename, lookup_flags, &path);
 620	if (!error) {
 621		error = chmod_common(&path, mode);
 622		path_put(&path);
 623		if (retry_estale(error, lookup_flags)) {
 624			lookup_flags |= LOOKUP_REVAL;
 625			goto retry;
 626		}
 627	}
 628	return error;
 629}
 630
 631SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename,
 632		umode_t, mode)
 633{
 634	return do_fchmodat(dfd, filename, mode);
 635}
 636
 637SYSCALL_DEFINE2(chmod, const char __user *, filename, umode_t, mode)
 638{
 639	return do_fchmodat(AT_FDCWD, filename, mode);
 640}
 641
 642int chown_common(const struct path *path, uid_t user, gid_t group)
 643{
 644	struct inode *inode = path->dentry->d_inode;
 645	struct inode *delegated_inode = NULL;
 646	int error;
 647	struct iattr newattrs;
 648	kuid_t uid;
 649	kgid_t gid;
 650
 651	uid = make_kuid(current_user_ns(), user);
 652	gid = make_kgid(current_user_ns(), group);
 653
 654retry_deleg:
 655	newattrs.ia_valid =  ATTR_CTIME;
 656	if (user != (uid_t) -1) {
 657		if (!uid_valid(uid))
 658			return -EINVAL;
 659		newattrs.ia_valid |= ATTR_UID;
 660		newattrs.ia_uid = uid;
 661	}
 662	if (group != (gid_t) -1) {
 663		if (!gid_valid(gid))
 664			return -EINVAL;
 665		newattrs.ia_valid |= ATTR_GID;
 666		newattrs.ia_gid = gid;
 667	}
 668	if (!S_ISDIR(inode->i_mode))
 669		newattrs.ia_valid |=
 670			ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_KILL_PRIV;
 671	inode_lock(inode);
 672	error = security_path_chown(path, uid, gid);
 673	if (!error)
 674		error = notify_change(path->dentry, &newattrs, &delegated_inode);
 675	inode_unlock(inode);
 676	if (delegated_inode) {
 677		error = break_deleg_wait(&delegated_inode);
 678		if (!error)
 679			goto retry_deleg;
 680	}
 681	return error;
 682}
 683
 684int do_fchownat(int dfd, const char __user *filename, uid_t user, gid_t group,
 685		int flag)
 686{
 687	struct path path;
 688	int error = -EINVAL;
 689	int lookup_flags;
 690
 691	if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
 692		goto out;
 693
 694	lookup_flags = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
 695	if (flag & AT_EMPTY_PATH)
 696		lookup_flags |= LOOKUP_EMPTY;
 697retry:
 698	error = user_path_at(dfd, filename, lookup_flags, &path);
 699	if (error)
 700		goto out;
 701	error = mnt_want_write(path.mnt);
 702	if (error)
 703		goto out_release;
 704	error = chown_common(&path, user, group);
 705	mnt_drop_write(path.mnt);
 706out_release:
 707	path_put(&path);
 708	if (retry_estale(error, lookup_flags)) {
 709		lookup_flags |= LOOKUP_REVAL;
 710		goto retry;
 711	}
 712out:
 713	return error;
 714}
 715
 716SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user,
 717		gid_t, group, int, flag)
 718{
 719	return do_fchownat(dfd, filename, user, group, flag);
 720}
 721
 722SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group)
 723{
 724	return do_fchownat(AT_FDCWD, filename, user, group, 0);
 725}
 726
 727SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group)
 728{
 729	return do_fchownat(AT_FDCWD, filename, user, group,
 730			   AT_SYMLINK_NOFOLLOW);
 731}
 732
 733int vfs_fchown(struct file *file, uid_t user, gid_t group)
 734{
 735	int error;
 
 
 
 
 736
 737	error = mnt_want_write_file(file);
 738	if (error)
 739		return error;
 740	audit_file(file);
 741	error = chown_common(&file->f_path, user, group);
 742	mnt_drop_write_file(file);
 
 
 
 743	return error;
 744}
 745
 746int ksys_fchown(unsigned int fd, uid_t user, gid_t group)
 747{
 748	struct fd f = fdget(fd);
 749	int error = -EBADF;
 750
 751	if (f.file) {
 752		error = vfs_fchown(f.file, user, group);
 753		fdput(f);
 754	}
 755	return error;
 756}
 757
 758SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group)
 759{
 760	return ksys_fchown(fd, user, group);
 761}
 762
 763static int do_dentry_open(struct file *f,
 764			  struct inode *inode,
 765			  int (*open)(struct inode *, struct file *))
 
 766{
 767	static const struct file_operations empty_fops = {};
 768	int error;
 769
 
 
 
 770	path_get(&f->f_path);
 771	f->f_inode = inode;
 772	f->f_mapping = inode->i_mapping;
 773	f->f_wb_err = filemap_sample_wb_err(f->f_mapping);
 774	f->f_sb_err = file_sample_sb_err(f);
 775
 776	if (unlikely(f->f_flags & O_PATH)) {
 777		f->f_mode = FMODE_PATH | FMODE_OPENED;
 778		f->f_op = &empty_fops;
 779		return 0;
 780	}
 781
 782	if (f->f_mode & FMODE_WRITE && !special_file(inode->i_mode)) {
 783		error = get_write_access(inode);
 784		if (unlikely(error))
 785			goto cleanup_file;
 786		error = __mnt_want_write(f->f_path.mnt);
 787		if (unlikely(error)) {
 788			put_write_access(inode);
 789			goto cleanup_file;
 790		}
 791		f->f_mode |= FMODE_WRITER;
 792	}
 793
 794	/* POSIX.1-2008/SUSv4 Section XSI 2.9.7 */
 795	if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode))
 796		f->f_mode |= FMODE_ATOMIC_POS;
 797
 798	f->f_op = fops_get(inode->i_fop);
 799	if (WARN_ON(!f->f_op)) {
 800		error = -ENODEV;
 801		goto cleanup_all;
 802	}
 803
 804	error = security_file_open(f);
 805	if (error)
 806		goto cleanup_all;
 807
 808	error = break_lease(locks_inode(f), f->f_flags);
 809	if (error)
 810		goto cleanup_all;
 811
 812	/* normally all 3 are set; ->open() can clear them if needed */
 813	f->f_mode |= FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE;
 814	if (!open)
 815		open = f->f_op->open;
 816	if (open) {
 817		error = open(inode, f);
 818		if (error)
 819			goto cleanup_all;
 820	}
 821	f->f_mode |= FMODE_OPENED;
 822	if ((f->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
 823		i_readcount_inc(inode);
 824	if ((f->f_mode & FMODE_READ) &&
 825	     likely(f->f_op->read || f->f_op->read_iter))
 826		f->f_mode |= FMODE_CAN_READ;
 827	if ((f->f_mode & FMODE_WRITE) &&
 828	     likely(f->f_op->write || f->f_op->write_iter))
 829		f->f_mode |= FMODE_CAN_WRITE;
 830
 831	f->f_write_hint = WRITE_LIFE_NOT_SET;
 832	f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
 833
 834	file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);
 835
 836	/* NB: we're sure to have correct a_ops only after f_op->open */
 837	if (f->f_flags & O_DIRECT) {
 838		if (!f->f_mapping->a_ops || !f->f_mapping->a_ops->direct_IO)
 839			return -EINVAL;
 840	}
 841
 842	/*
 843	 * XXX: Huge page cache doesn't support writing yet. Drop all page
 844	 * cache for this file before processing writes.
 845	 */
 846	if ((f->f_mode & FMODE_WRITE) && filemap_nr_thps(inode->i_mapping))
 847		truncate_pagecache(inode, 0);
 848
 849	return 0;
 850
 851cleanup_all:
 852	if (WARN_ON_ONCE(error > 0))
 853		error = -EINVAL;
 854	fops_put(f->f_op);
 855	if (f->f_mode & FMODE_WRITER) {
 856		put_write_access(inode);
 857		__mnt_drop_write(f->f_path.mnt);
 858	}
 859cleanup_file:
 860	path_put(&f->f_path);
 861	f->f_path.mnt = NULL;
 862	f->f_path.dentry = NULL;
 863	f->f_inode = NULL;
 864	return error;
 865}
 866
 867/**
 868 * finish_open - finish opening a file
 869 * @file: file pointer
 870 * @dentry: pointer to dentry
 871 * @open: open callback
 872 * @opened: state of open
 873 *
 874 * This can be used to finish opening a file passed to i_op->atomic_open().
 875 *
 876 * If the open callback is set to NULL, then the standard f_op->open()
 877 * filesystem callback is substituted.
 878 *
 879 * NB: the dentry reference is _not_ consumed.  If, for example, the dentry is
 880 * the return value of d_splice_alias(), then the caller needs to perform dput()
 881 * on it after finish_open().
 882 *
 
 
 
 883 * Returns zero on success or -errno if the open failed.
 884 */
 885int finish_open(struct file *file, struct dentry *dentry,
 886		int (*open)(struct inode *, struct file *))
 
 887{
 888	BUG_ON(file->f_mode & FMODE_OPENED); /* once it's opened, it's opened */
 
 889
 890	file->f_path.dentry = dentry;
 891	return do_dentry_open(file, d_backing_inode(dentry), open);
 
 
 
 
 
 892}
 893EXPORT_SYMBOL(finish_open);
 894
 895/**
 896 * finish_no_open - finish ->atomic_open() without opening the file
 897 *
 898 * @file: file pointer
 899 * @dentry: dentry or NULL (as returned from ->lookup())
 900 *
 901 * This can be used to set the result of a successful lookup in ->atomic_open().
 902 *
 903 * NB: unlike finish_open() this function does consume the dentry reference and
 904 * the caller need not dput() it.
 905 *
 906 * Returns "0" which must be the return value of ->atomic_open() after having
 907 * called this function.
 908 */
 909int finish_no_open(struct file *file, struct dentry *dentry)
 910{
 911	file->f_path.dentry = dentry;
 912	return 0;
 913}
 914EXPORT_SYMBOL(finish_no_open);
 915
 916char *file_path(struct file *filp, char *buf, int buflen)
 917{
 918	return d_path(&filp->f_path, buf, buflen);
 919}
 920EXPORT_SYMBOL(file_path);
 921
 922/**
 923 * vfs_open - open the file at the given path
 924 * @path: path to open
 925 * @file: newly allocated file with f_flag initialized
 926 * @cred: credentials to use
 927 */
 928int vfs_open(const struct path *path, struct file *file)
 
 929{
 
 
 
 
 
 930	file->f_path = *path;
 931	return do_dentry_open(file, d_backing_inode(path->dentry), NULL);
 932}
 933
 934struct file *dentry_open(const struct path *path, int flags,
 935			 const struct cred *cred)
 936{
 937	int error;
 938	struct file *f;
 939
 940	validate_creds(cred);
 941
 942	/* We must always pass in a valid mount pointer. */
 943	BUG_ON(!path->mnt);
 944
 945	f = alloc_empty_file(flags, cred);
 946	if (!IS_ERR(f)) {
 947		error = vfs_open(path, f);
 948		if (error) {
 949			fput(f);
 
 
 
 
 
 
 
 
 950			f = ERR_PTR(error);
 951		}
 952	}
 953	return f;
 954}
 955EXPORT_SYMBOL(dentry_open);
 956
 957struct file *open_with_fake_path(const struct path *path, int flags,
 958				struct inode *inode, const struct cred *cred)
 959{
 960	struct file *f = alloc_empty_file_noaccount(flags, cred);
 961	if (!IS_ERR(f)) {
 962		int error;
 963
 964		f->f_path = *path;
 965		error = do_dentry_open(f, inode, NULL);
 966		if (error) {
 967			fput(f);
 968			f = ERR_PTR(error);
 969		}
 970	}
 971	return f;
 972}
 973EXPORT_SYMBOL(open_with_fake_path);
 974
 975#define WILL_CREATE(flags)	(flags & (O_CREAT | __O_TMPFILE))
 976#define O_PATH_FLAGS		(O_DIRECTORY | O_NOFOLLOW | O_PATH | O_CLOEXEC)
 977
 978inline struct open_how build_open_how(int flags, umode_t mode)
 979{
 980	struct open_how how = {
 981		.flags = flags & VALID_OPEN_FLAGS,
 982		.mode = mode & S_IALLUGO,
 983	};
 984
 985	/* O_PATH beats everything else. */
 986	if (how.flags & O_PATH)
 987		how.flags &= O_PATH_FLAGS;
 988	/* Modes should only be set for create-like flags. */
 989	if (!WILL_CREATE(how.flags))
 990		how.mode = 0;
 991	return how;
 992}
 993
 994inline int build_open_flags(const struct open_how *how, struct open_flags *op)
 995{
 996	int flags = how->flags;
 997	int lookup_flags = 0;
 998	int acc_mode = ACC_MODE(flags);
 999
 
 
 
 
 
1000	/* Must never be set by userspace */
1001	flags &= ~(FMODE_NONOTIFY | O_CLOEXEC);
1002
1003	/*
1004	 * Older syscalls implicitly clear all of the invalid flags or argument
1005	 * values before calling build_open_flags(), but openat2(2) checks all
1006	 * of its arguments.
 
1007	 */
1008	if (flags & ~VALID_OPEN_FLAGS)
1009		return -EINVAL;
1010	if (how->resolve & ~VALID_RESOLVE_FLAGS)
1011		return -EINVAL;
1012
1013	/* Deal with the mode. */
1014	if (WILL_CREATE(flags)) {
1015		if (how->mode & ~S_IALLUGO)
1016			return -EINVAL;
1017		op->mode = how->mode | S_IFREG;
1018	} else {
1019		if (how->mode != 0)
1020			return -EINVAL;
1021		op->mode = 0;
1022	}
1023
1024	/*
1025	 * In order to ensure programs get explicit errors when trying to use
1026	 * O_TMPFILE on old kernels, O_TMPFILE is implemented such that it
1027	 * looks like (O_DIRECTORY|O_RDWR & ~O_CREAT) to old kernels. But we
1028	 * have to require userspace to explicitly set it.
1029	 */
1030	if (flags & __O_TMPFILE) {
1031		if ((flags & O_TMPFILE_MASK) != O_TMPFILE)
1032			return -EINVAL;
1033		if (!(acc_mode & MAY_WRITE))
1034			return -EINVAL;
1035	}
1036	if (flags & O_PATH) {
1037		/* O_PATH only permits certain other flags to be set. */
1038		if (flags & ~O_PATH_FLAGS)
1039			return -EINVAL;
 
1040		acc_mode = 0;
1041	}
1042
1043	/*
1044	 * O_SYNC is implemented as __O_SYNC|O_DSYNC.  As many places only
1045	 * check for O_DSYNC if the need any syncing at all we enforce it's
1046	 * always set instead of having to deal with possibly weird behaviour
1047	 * for malicious applications setting only __O_SYNC.
1048	 */
1049	if (flags & __O_SYNC)
1050		flags |= O_DSYNC;
1051
1052	op->open_flag = flags;
1053
1054	/* O_TRUNC implies we need access checks for write permissions */
1055	if (flags & O_TRUNC)
1056		acc_mode |= MAY_WRITE;
1057
1058	/* Allow the LSM permission hook to distinguish append
1059	   access from general write access. */
1060	if (flags & O_APPEND)
1061		acc_mode |= MAY_APPEND;
1062
1063	op->acc_mode = acc_mode;
1064
1065	op->intent = flags & O_PATH ? 0 : LOOKUP_OPEN;
1066
1067	if (flags & O_CREAT) {
1068		op->intent |= LOOKUP_CREATE;
1069		if (flags & O_EXCL) {
1070			op->intent |= LOOKUP_EXCL;
1071			flags |= O_NOFOLLOW;
1072		}
1073	}
1074
1075	if (flags & O_DIRECTORY)
1076		lookup_flags |= LOOKUP_DIRECTORY;
1077	if (!(flags & O_NOFOLLOW))
1078		lookup_flags |= LOOKUP_FOLLOW;
1079
1080	if (how->resolve & RESOLVE_NO_XDEV)
1081		lookup_flags |= LOOKUP_NO_XDEV;
1082	if (how->resolve & RESOLVE_NO_MAGICLINKS)
1083		lookup_flags |= LOOKUP_NO_MAGICLINKS;
1084	if (how->resolve & RESOLVE_NO_SYMLINKS)
1085		lookup_flags |= LOOKUP_NO_SYMLINKS;
1086	if (how->resolve & RESOLVE_BENEATH)
1087		lookup_flags |= LOOKUP_BENEATH;
1088	if (how->resolve & RESOLVE_IN_ROOT)
1089		lookup_flags |= LOOKUP_IN_ROOT;
1090
1091	op->lookup_flags = lookup_flags;
1092	return 0;
1093}
1094
1095/**
1096 * file_open_name - open file and return file pointer
1097 *
1098 * @name:	struct filename containing path to open
1099 * @flags:	open flags as per the open(2) second argument
1100 * @mode:	mode for the new file if O_CREAT is set, else ignored
1101 *
1102 * This is the helper to open a file from kernelspace if you really
1103 * have to.  But in generally you should not do this, so please move
1104 * along, nothing to see here..
1105 */
1106struct file *file_open_name(struct filename *name, int flags, umode_t mode)
1107{
1108	struct open_flags op;
1109	struct open_how how = build_open_how(flags, mode);
1110	int err = build_open_flags(&how, &op);
1111	if (err)
1112		return ERR_PTR(err);
1113	return do_filp_open(AT_FDCWD, name, &op);
1114}
1115
1116/**
1117 * filp_open - open file and return file pointer
1118 *
1119 * @filename:	path to open
1120 * @flags:	open flags as per the open(2) second argument
1121 * @mode:	mode for the new file if O_CREAT is set, else ignored
1122 *
1123 * This is the helper to open a file from kernelspace if you really
1124 * have to.  But in generally you should not do this, so please move
1125 * along, nothing to see here..
1126 */
1127struct file *filp_open(const char *filename, int flags, umode_t mode)
1128{
1129	struct filename *name = getname_kernel(filename);
1130	struct file *file = ERR_CAST(name);
1131	
1132	if (!IS_ERR(name)) {
1133		file = file_open_name(name, flags, mode);
1134		putname(name);
1135	}
1136	return file;
1137}
1138EXPORT_SYMBOL(filp_open);
1139
1140struct file *file_open_root(struct dentry *dentry, struct vfsmount *mnt,
1141			    const char *filename, int flags, umode_t mode)
1142{
1143	struct open_flags op;
1144	struct open_how how = build_open_how(flags, mode);
1145	int err = build_open_flags(&how, &op);
1146	if (err)
1147		return ERR_PTR(err);
1148	return do_file_open_root(dentry, mnt, filename, &op);
1149}
1150EXPORT_SYMBOL(file_open_root);
1151
1152static long do_sys_openat2(int dfd, const char __user *filename,
1153			   struct open_how *how)
1154{
1155	struct open_flags op;
1156	int fd = build_open_flags(how, &op);
1157	struct filename *tmp;
1158
1159	if (fd)
1160		return fd;
1161
1162	tmp = getname(filename);
1163	if (IS_ERR(tmp))
1164		return PTR_ERR(tmp);
1165
1166	fd = get_unused_fd_flags(how->flags);
1167	if (fd >= 0) {
1168		struct file *f = do_filp_open(dfd, tmp, &op);
1169		if (IS_ERR(f)) {
1170			put_unused_fd(fd);
1171			fd = PTR_ERR(f);
1172		} else {
1173			fsnotify_open(f);
1174			fd_install(fd, f);
1175		}
1176	}
1177	putname(tmp);
1178	return fd;
1179}
1180
1181long do_sys_open(int dfd, const char __user *filename, int flags, umode_t mode)
1182{
1183	struct open_how how = build_open_how(flags, mode);
1184	return do_sys_openat2(dfd, filename, &how);
1185}
1186
1187
1188SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)
1189{
1190	if (force_o_largefile())
1191		flags |= O_LARGEFILE;
 
1192	return do_sys_open(AT_FDCWD, filename, flags, mode);
1193}
1194
1195SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags,
1196		umode_t, mode)
1197{
1198	if (force_o_largefile())
1199		flags |= O_LARGEFILE;
1200	return do_sys_open(dfd, filename, flags, mode);
1201}
1202
1203SYSCALL_DEFINE4(openat2, int, dfd, const char __user *, filename,
1204		struct open_how __user *, how, size_t, usize)
1205{
1206	int err;
1207	struct open_how tmp;
1208
1209	BUILD_BUG_ON(sizeof(struct open_how) < OPEN_HOW_SIZE_VER0);
1210	BUILD_BUG_ON(sizeof(struct open_how) != OPEN_HOW_SIZE_LATEST);
1211
1212	if (unlikely(usize < OPEN_HOW_SIZE_VER0))
1213		return -EINVAL;
1214
1215	err = copy_struct_from_user(&tmp, sizeof(tmp), how, usize);
1216	if (err)
1217		return err;
1218
1219	/* O_LARGEFILE is only allowed for non-O_PATH. */
1220	if (!(tmp.flags & O_PATH) && force_o_largefile())
1221		tmp.flags |= O_LARGEFILE;
1222
1223	return do_sys_openat2(dfd, filename, &tmp);
1224}
1225
1226#ifdef CONFIG_COMPAT
1227/*
1228 * Exactly like sys_open(), except that it doesn't set the
1229 * O_LARGEFILE flag.
1230 */
1231COMPAT_SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)
1232{
1233	return do_sys_open(AT_FDCWD, filename, flags, mode);
1234}
1235
1236/*
1237 * Exactly like sys_openat(), except that it doesn't set the
1238 * O_LARGEFILE flag.
1239 */
1240COMPAT_SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags, umode_t, mode)
1241{
1242	return do_sys_open(dfd, filename, flags, mode);
1243}
1244#endif
1245
1246#ifndef __alpha__
1247
1248/*
1249 * For backward compatibility?  Maybe this should be moved
1250 * into arch/i386 instead?
1251 */
1252SYSCALL_DEFINE2(creat, const char __user *, pathname, umode_t, mode)
1253{
1254	int flags = O_CREAT | O_WRONLY | O_TRUNC;
 
1255
1256	if (force_o_largefile())
1257		flags |= O_LARGEFILE;
1258	return do_sys_open(AT_FDCWD, pathname, flags, mode);
1259}
1260#endif
1261
1262/*
1263 * "id" is the POSIX thread ID. We use the
1264 * files pointer for this..
1265 */
1266int filp_close(struct file *filp, fl_owner_t id)
1267{
1268	int retval = 0;
1269
1270	if (!file_count(filp)) {
1271		printk(KERN_ERR "VFS: Close: file count is 0\n");
1272		return 0;
1273	}
1274
1275	if (filp->f_op->flush)
1276		retval = filp->f_op->flush(filp, id);
1277
1278	if (likely(!(filp->f_mode & FMODE_PATH))) {
1279		dnotify_flush(filp, id);
1280		locks_remove_posix(filp, id);
1281	}
1282	fput(filp);
1283	return retval;
1284}
1285
1286EXPORT_SYMBOL(filp_close);
1287
1288/*
1289 * Careful here! We test whether the file pointer is NULL before
1290 * releasing the fd. This ensures that one clone task can't release
1291 * an fd while another clone is opening it.
1292 */
1293SYSCALL_DEFINE1(close, unsigned int, fd)
1294{
1295	int retval = __close_fd(current->files, fd);
1296
1297	/* can't restart close syscall because file table entry was cleared */
1298	if (unlikely(retval == -ERESTARTSYS ||
1299		     retval == -ERESTARTNOINTR ||
1300		     retval == -ERESTARTNOHAND ||
1301		     retval == -ERESTART_RESTARTBLOCK))
1302		retval = -EINTR;
1303
1304	return retval;
1305}
1306
1307/**
1308 * close_range() - Close all file descriptors in a given range.
1309 *
1310 * @fd:     starting file descriptor to close
1311 * @max_fd: last file descriptor to close
1312 * @flags:  reserved for future extensions
1313 *
1314 * This closes a range of file descriptors. All file descriptors
1315 * from @fd up to and including @max_fd are closed.
1316 * Currently, errors to close a given file descriptor are ignored.
1317 */
1318SYSCALL_DEFINE3(close_range, unsigned int, fd, unsigned int, max_fd,
1319		unsigned int, flags)
1320{
1321	return __close_range(fd, max_fd, flags);
1322}
1323
1324/*
1325 * This routine simulates a hangup on the tty, to arrange that users
1326 * are given clean terminals at login time.
1327 */
1328SYSCALL_DEFINE0(vhangup)
1329{
1330	if (capable(CAP_SYS_TTY_CONFIG)) {
1331		tty_vhangup_self();
1332		return 0;
1333	}
1334	return -EPERM;
1335}
1336
1337/*
1338 * Called when an inode is about to be open.
1339 * We use this to disallow opening large files on 32bit systems if
1340 * the caller didn't specify O_LARGEFILE.  On 64bit systems we force
1341 * on this flag in sys_open.
1342 */
1343int generic_file_open(struct inode * inode, struct file * filp)
1344{
1345	if (!(filp->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS)
1346		return -EOVERFLOW;
1347	return 0;
1348}
1349
1350EXPORT_SYMBOL(generic_file_open);
1351
1352/*
1353 * This is used by subsystems that don't want seekable
1354 * file descriptors. The function is not supposed to ever fail, the only
1355 * reason it returns an 'int' and not 'void' is so that it can be plugged
1356 * directly into file_operations structure.
1357 */
1358int nonseekable_open(struct inode *inode, struct file *filp)
1359{
1360	filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);
1361	return 0;
1362}
1363
1364EXPORT_SYMBOL(nonseekable_open);
1365
1366/*
1367 * stream_open is used by subsystems that want stream-like file descriptors.
1368 * Such file descriptors are not seekable and don't have notion of position
1369 * (file.f_pos is always 0 and ppos passed to .read()/.write() is always NULL).
1370 * Contrary to file descriptors of other regular files, .read() and .write()
1371 * can run simultaneously.
1372 *
1373 * stream_open never fails and is marked to return int so that it could be
1374 * directly used as file_operations.open .
1375 */
1376int stream_open(struct inode *inode, struct file *filp)
1377{
1378	filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE | FMODE_ATOMIC_POS);
1379	filp->f_mode |= FMODE_STREAM;
1380	return 0;
1381}
1382
1383EXPORT_SYMBOL(stream_open);