open.c

   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/dnotify.h>
  33#include <linux/compat.h>
  34#include <linux/mnt_idmapping.h>
  35#include <linux/filelock.h>
  36
  37#include "internal.h"
  38
  39int do_truncate(struct mnt_idmap *idmap, struct dentry *dentry,
  40		loff_t length, unsigned int time_attrs, struct file *filp)
  41{
  42	int ret;
  43	struct iattr newattrs;
  44
  45	/* Not pretty: "inode->i_size" shouldn't really be signed. But it is. */
  46	if (length < 0)
  47		return -EINVAL;
  48
  49	newattrs.ia_size = length;
  50	newattrs.ia_valid = ATTR_SIZE | time_attrs;
  51	if (filp) {
  52		newattrs.ia_file = filp;
  53		newattrs.ia_valid |= ATTR_FILE;
  54	}
  55
  56	/* Remove suid, sgid, and file capabilities on truncate too */
  57	ret = dentry_needs_remove_privs(idmap, dentry);
  58	if (ret < 0)
  59		return ret;
  60	if (ret)
  61		newattrs.ia_valid |= ret | ATTR_FORCE;
  62
  63	ret = inode_lock_killable(dentry->d_inode);
  64	if (ret)
  65		return ret;
  66
  67	/* Note any delegations or leases have already been broken: */
  68	ret = notify_change(idmap, dentry, &newattrs, NULL);
  69	inode_unlock(dentry->d_inode);
  70	return ret;
  71}
  72
  73int vfs_truncate(const struct path *path, loff_t length)
  74{
  75	struct mnt_idmap *idmap;
  76	struct inode *inode;
  77	int error;
  78
  79	inode = path->dentry->d_inode;
  80
  81	/* For directories it's -EISDIR, for other non-regulars - -EINVAL */
  82	if (S_ISDIR(inode->i_mode))
  83		return -EISDIR;
  84	if (!S_ISREG(inode->i_mode))
  85		return -EINVAL;
  86
  87	idmap = mnt_idmap(path->mnt);
  88	error = inode_permission(idmap, inode, MAY_WRITE);
  89	if (error)
  90		return error;
  91
  92	error = fsnotify_truncate_perm(path, length);
  93	if (error)
  94		return error;
  95
  96	error = mnt_want_write(path->mnt);
  97	if (error)
  98		return error;
  99
 100	error = -EPERM;
 101	if (IS_APPEND(inode))
 102		goto mnt_drop_write_and_out;
 103
 104	error = get_write_access(inode);
 105	if (error)
 106		goto mnt_drop_write_and_out;
 107
 108	/*
 109	 * Make sure that there are no leases.  get_write_access() protects
 110	 * against the truncate racing with a lease-granting setlease().
 111	 */
 112	error = break_lease(inode, O_WRONLY);
 113	if (error)
 114		goto put_write_and_out;
 115
 116	error = security_path_truncate(path);
 117	if (!error)
 118		error = do_truncate(idmap, path->dentry, length, 0, NULL);
 119
 120put_write_and_out:
 121	put_write_access(inode);
 122mnt_drop_write_and_out:
 123	mnt_drop_write(path->mnt);
 124
 125	return error;
 126}
 127EXPORT_SYMBOL_GPL(vfs_truncate);
 128
 129int do_sys_truncate(const char __user *pathname, loff_t length)
 130{
 131	unsigned int lookup_flags = LOOKUP_FOLLOW;
 132	struct path path;
 133	int error;
 134
 135	if (length < 0)	/* sorry, but loff_t says... */
 136		return -EINVAL;
 137
 138retry:
 139	error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
 140	if (!error) {
 141		error = vfs_truncate(&path, length);
 142		path_put(&path);
 143	}
 144	if (retry_estale(error, lookup_flags)) {
 145		lookup_flags |= LOOKUP_REVAL;
 146		goto retry;
 147	}
 148	return error;
 149}
 150
 151SYSCALL_DEFINE2(truncate, const char __user *, path, long, length)
 152{
 153	return do_sys_truncate(path, length);
 154}
 155
 156#ifdef CONFIG_COMPAT
 157COMPAT_SYSCALL_DEFINE2(truncate, const char __user *, path, compat_off_t, length)
 158{
 159	return do_sys_truncate(path, length);
 160}
 161#endif
 162
 163int do_ftruncate(struct file *file, loff_t length, int small)
 164{
 165	struct inode *inode;
 166	struct dentry *dentry;
 167	int error;
 168
 169	/* explicitly opened as large or we are on 64-bit box */
 170	if (file->f_flags & O_LARGEFILE)
 171		small = 0;
 172
 173	dentry = file->f_path.dentry;
 174	inode = dentry->d_inode;
 175	if (!S_ISREG(inode->i_mode) || !(file->f_mode & FMODE_WRITE))
 176		return -EINVAL;
 177
 178	/* Cannot ftruncate over 2^31 bytes without large file support */
 179	if (small && length > MAX_NON_LFS)
 180		return -EINVAL;
 181
 182	/* Check IS_APPEND on real upper inode */
 183	if (IS_APPEND(file_inode(file)))
 184		return -EPERM;
 185
 186	error = security_file_truncate(file);
 187	if (error)
 188		return error;
 189
 190	error = fsnotify_truncate_perm(&file->f_path, length);
 191	if (error)
 192		return error;
 193
 194	scoped_guard(super_write, inode->i_sb)
 195		return do_truncate(file_mnt_idmap(file), dentry, length,
 196				   ATTR_MTIME | ATTR_CTIME, file);
 197}
 198
 199int do_sys_ftruncate(unsigned int fd, loff_t length, int small)
 200{
 201	if (length < 0)
 202		return -EINVAL;
 203	CLASS(fd, f)(fd);
 204	if (fd_empty(f))
 205		return -EBADF;
 206
 207	return do_ftruncate(fd_file(f), length, small);
 208}
 209
 210SYSCALL_DEFINE2(ftruncate, unsigned int, fd, off_t, length)
 211{
 212	return do_sys_ftruncate(fd, length, 1);
 213}
 214
 215#ifdef CONFIG_COMPAT
 216COMPAT_SYSCALL_DEFINE2(ftruncate, unsigned int, fd, compat_off_t, length)
 217{
 218	return do_sys_ftruncate(fd, length, 1);
 219}
 220#endif
 221
 222/* LFS versions of truncate are only needed on 32 bit machines */
 223#if BITS_PER_LONG == 32
 224SYSCALL_DEFINE2(truncate64, const char __user *, path, loff_t, length)
 225{
 226	return do_sys_truncate(path, length);
 227}
 228
 229SYSCALL_DEFINE2(ftruncate64, unsigned int, fd, loff_t, length)
 230{
 231	return do_sys_ftruncate(fd, length, 0);
 232}
 233#endif /* BITS_PER_LONG == 32 */
 234
 235#if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_TRUNCATE64)
 236COMPAT_SYSCALL_DEFINE3(truncate64, const char __user *, pathname,
 237		       compat_arg_u64_dual(length))
 238{
 239	return ksys_truncate(pathname, compat_arg_u64_glue(length));
 240}
 241#endif
 242
 243#if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_FTRUNCATE64)
 244COMPAT_SYSCALL_DEFINE3(ftruncate64, unsigned int, fd,
 245		       compat_arg_u64_dual(length))
 246{
 247	return ksys_ftruncate(fd, compat_arg_u64_glue(length));
 248}
 249#endif
 250
 251int vfs_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
 252{
 253	struct inode *inode = file_inode(file);
 254	int ret;
 255	loff_t sum;
 256
 257	if (offset < 0 || len <= 0)
 258		return -EINVAL;
 259
 260	if (mode & ~(FALLOC_FL_MODE_MASK | FALLOC_FL_KEEP_SIZE))
 261		return -EOPNOTSUPP;
 262
 263	/*
 264	 * Modes are exclusive, even if that is not obvious from the encoding
 265	 * as bit masks and the mix with the flag in the same namespace.
 266	 *
 267	 * To make things even more complicated, FALLOC_FL_ALLOCATE_RANGE is
 268	 * encoded as no bit set.
 269	 */
 270	switch (mode & FALLOC_FL_MODE_MASK) {
 271	case FALLOC_FL_ALLOCATE_RANGE:
 272	case FALLOC_FL_UNSHARE_RANGE:
 273	case FALLOC_FL_ZERO_RANGE:
 274		break;
 275	case FALLOC_FL_PUNCH_HOLE:
 276		if (!(mode & FALLOC_FL_KEEP_SIZE))
 277			return -EOPNOTSUPP;
 278		break;
 279	case FALLOC_FL_COLLAPSE_RANGE:
 280	case FALLOC_FL_INSERT_RANGE:
 281	case FALLOC_FL_WRITE_ZEROES:
 282		if (mode & FALLOC_FL_KEEP_SIZE)
 283			return -EOPNOTSUPP;
 284		break;
 285	default:
 286		return -EOPNOTSUPP;
 287	}
 288
 289	if (!(file->f_mode & FMODE_WRITE))
 290		return -EBADF;
 291
 292	/*
 293	 * On append-only files only space preallocation is supported.
 294	 */
 295	if ((mode & ~FALLOC_FL_KEEP_SIZE) && IS_APPEND(inode))
 296		return -EPERM;
 297
 298	if (IS_IMMUTABLE(inode))
 299		return -EPERM;
 300
 301	/*
 302	 * We cannot allow any fallocate operation on an active swapfile
 303	 */
 304	if (IS_SWAPFILE(inode))
 305		return -ETXTBSY;
 306
 307	/*
 308	 * Revalidate the write permissions, in case security policy has
 309	 * changed since the files were opened.
 310	 */
 311	ret = security_file_permission(file, MAY_WRITE);
 312	if (ret)
 313		return ret;
 314
 315	ret = fsnotify_file_area_perm(file, MAY_WRITE, &offset, len);
 316	if (ret)
 317		return ret;
 318
 319	if (S_ISFIFO(inode->i_mode))
 320		return -ESPIPE;
 321
 322	if (S_ISDIR(inode->i_mode))
 323		return -EISDIR;
 324
 325	if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
 326		return -ENODEV;
 327
 328	/* Check for wraparound */
 329	if (check_add_overflow(offset, len, &sum))
 330		return -EFBIG;
 331
 332	if (sum > inode->i_sb->s_maxbytes)
 333		return -EFBIG;
 334
 335	if (!file->f_op->fallocate)
 336		return -EOPNOTSUPP;
 337
 338	file_start_write(file);
 339	ret = file->f_op->fallocate(file, mode, offset, len);
 340
 341	/*
 342	 * Create inotify and fanotify events.
 343	 *
 344	 * To keep the logic simple always create events if fallocate succeeds.
 345	 * This implies that events are even created if the file size remains
 346	 * unchanged, e.g. when using flag FALLOC_FL_KEEP_SIZE.
 347	 */
 348	if (ret == 0)
 349		fsnotify_modify(file);
 350
 351	file_end_write(file);
 352	return ret;
 353}
 354EXPORT_SYMBOL_GPL(vfs_fallocate);
 355
 356int ksys_fallocate(int fd, int mode, loff_t offset, loff_t len)
 357{
 358	CLASS(fd, f)(fd);
 359
 360	if (fd_empty(f))
 361		return -EBADF;
 362
 363	return vfs_fallocate(fd_file(f), mode, offset, len);
 364}
 365
 366SYSCALL_DEFINE4(fallocate, int, fd, int, mode, loff_t, offset, loff_t, len)
 367{
 368	return ksys_fallocate(fd, mode, offset, len);
 369}
 370
 371#if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_FALLOCATE)
 372COMPAT_SYSCALL_DEFINE6(fallocate, int, fd, int, mode, compat_arg_u64_dual(offset),
 373		       compat_arg_u64_dual(len))
 374{
 375	return ksys_fallocate(fd, mode, compat_arg_u64_glue(offset),
 376			      compat_arg_u64_glue(len));
 377}
 378#endif
 379
 380/*
 381 * access() needs to use the real uid/gid, not the effective uid/gid.
 382 * We do this by temporarily clearing all FS-related capabilities and
 383 * switching the fsuid/fsgid around to the real ones.
 384 *
 385 * Creating new credentials is expensive, so we try to skip doing it,
 386 * which we can if the result would match what we already got.
 387 */
 388static bool access_need_override_creds(int flags)
 389{
 390	const struct cred *cred;
 391
 392	if (flags & AT_EACCESS)
 393		return false;
 394
 395	cred = current_cred();
 396	if (!uid_eq(cred->fsuid, cred->uid) ||
 397	    !gid_eq(cred->fsgid, cred->gid))
 398		return true;
 399
 400	if (!issecure(SECURE_NO_SETUID_FIXUP)) {
 401		kuid_t root_uid = make_kuid(cred->user_ns, 0);
 402		if (!uid_eq(cred->uid, root_uid)) {
 403			if (!cap_isclear(cred->cap_effective))
 404				return true;
 405		} else {
 406			if (!cap_isidentical(cred->cap_effective,
 407			    cred->cap_permitted))
 408				return true;
 409		}
 410	}
 411
 412	return false;
 413}
 414
 415static const struct cred *access_override_creds(void)
 416{
 417	struct cred *override_cred;
 418
 419	override_cred = prepare_creds();
 420	if (!override_cred)
 421		return NULL;
 422
 423	/*
 424	 * XXX access_need_override_creds performs checks in hopes of skipping
 425	 * this work. Make sure it stays in sync if making any changes in this
 426	 * routine.
 427	 */
 428
 429	override_cred->fsuid = override_cred->uid;
 430	override_cred->fsgid = override_cred->gid;
 431
 432	if (!issecure(SECURE_NO_SETUID_FIXUP)) {
 433		/* Clear the capabilities if we switch to a non-root user */
 434		kuid_t root_uid = make_kuid(override_cred->user_ns, 0);
 435		if (!uid_eq(override_cred->uid, root_uid))
 436			cap_clear(override_cred->cap_effective);
 437		else
 438			override_cred->cap_effective =
 439				override_cred->cap_permitted;
 440	}
 441
 442	/*
 443	 * The new set of credentials can *only* be used in
 444	 * task-synchronous circumstances, and does not need
 445	 * RCU freeing, unless somebody then takes a separate
 446	 * reference to it.
 447	 *
 448	 * NOTE! This is _only_ true because this credential
 449	 * is used purely for override_creds() that installs
 450	 * it as the subjective cred. Other threads will be
 451	 * accessing ->real_cred, not the subjective cred.
 452	 *
 453	 * If somebody _does_ make a copy of this (using the
 454	 * 'get_current_cred()' function), that will clear the
 455	 * non_rcu field, because now that other user may be
 456	 * expecting RCU freeing. But normal thread-synchronous
 457	 * cred accesses will keep things non-racy to avoid RCU
 458	 * freeing.
 459	 */
 460	override_cred->non_rcu = 1;
 461	return override_creds(override_cred);
 462}
 463
 464static int do_faccessat(int dfd, const char __user *filename, int mode, int flags)
 465{
 466	struct path path;
 467	struct inode *inode;
 468	int res;
 469	unsigned int lookup_flags = LOOKUP_FOLLOW;
 470	const struct cred *old_cred = NULL;
 471
 472	if (mode & ~S_IRWXO)	/* where's F_OK, X_OK, W_OK, R_OK? */
 473		return -EINVAL;
 474
 475	if (flags & ~(AT_EACCESS | AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH))
 476		return -EINVAL;
 477
 478	if (flags & AT_SYMLINK_NOFOLLOW)
 479		lookup_flags &= ~LOOKUP_FOLLOW;
 480	if (flags & AT_EMPTY_PATH)
 481		lookup_flags |= LOOKUP_EMPTY;
 482
 483	if (access_need_override_creds(flags)) {
 484		old_cred = access_override_creds();
 485		if (!old_cred)
 486			return -ENOMEM;
 487	}
 488
 489retry:
 490	res = user_path_at(dfd, filename, lookup_flags, &path);
 491	if (res)
 492		goto out;
 493
 494	inode = d_backing_inode(path.dentry);
 495
 496	if ((mode & MAY_EXEC) && S_ISREG(inode->i_mode)) {
 497		/*
 498		 * MAY_EXEC on regular files is denied if the fs is mounted
 499		 * with the "noexec" flag.
 500		 */
 501		res = -EACCES;
 502		if (path_noexec(&path))
 503			goto out_path_release;
 504	}
 505
 506	res = inode_permission(mnt_idmap(path.mnt), inode, mode | MAY_ACCESS);
 507	/* SuS v2 requires we report a read only fs too */
 508	if (res || !(mode & S_IWOTH) || special_file(inode->i_mode))
 509		goto out_path_release;
 510	/*
 511	 * This is a rare case where using __mnt_is_readonly()
 512	 * is OK without a mnt_want/drop_write() pair.  Since
 513	 * no actual write to the fs is performed here, we do
 514	 * not need to telegraph to that to anyone.
 515	 *
 516	 * By doing this, we accept that this access is
 517	 * inherently racy and know that the fs may change
 518	 * state before we even see this result.
 519	 */
 520	if (__mnt_is_readonly(path.mnt))
 521		res = -EROFS;
 522
 523out_path_release:
 524	path_put(&path);
 525	if (retry_estale(res, lookup_flags)) {
 526		lookup_flags |= LOOKUP_REVAL;
 527		goto retry;
 528	}
 529out:
 530	if (old_cred)
 531		put_cred(revert_creds(old_cred));
 532
 533	return res;
 534}
 535
 536SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode)
 537{
 538	return do_faccessat(dfd, filename, mode, 0);
 539}
 540
 541SYSCALL_DEFINE4(faccessat2, int, dfd, const char __user *, filename, int, mode,
 542		int, flags)
 543{
 544	return do_faccessat(dfd, filename, mode, flags);
 545}
 546
 547SYSCALL_DEFINE2(access, const char __user *, filename, int, mode)
 548{
 549	return do_faccessat(AT_FDCWD, filename, mode, 0);
 550}
 551
 552SYSCALL_DEFINE1(chdir, const char __user *, filename)
 553{
 554	struct path path;
 555	int error;
 556	unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
 557retry:
 558	error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
 559	if (error)
 560		goto out;
 561
 562	error = path_permission(&path, MAY_EXEC | MAY_CHDIR);
 563	if (error)
 564		goto dput_and_out;
 565
 566	set_fs_pwd(current->fs, &path);
 567
 568dput_and_out:
 569	path_put(&path);
 570	if (retry_estale(error, lookup_flags)) {
 571		lookup_flags |= LOOKUP_REVAL;
 572		goto retry;
 573	}
 574out:
 575	return error;
 576}
 577
 578SYSCALL_DEFINE1(fchdir, unsigned int, fd)
 579{
 580	CLASS(fd_raw, f)(fd);
 581	int error;
 582
 583	if (fd_empty(f))
 584		return -EBADF;
 585
 586	if (!d_can_lookup(fd_file(f)->f_path.dentry))
 587		return -ENOTDIR;
 588
 589	error = file_permission(fd_file(f), MAY_EXEC | MAY_CHDIR);
 590	if (!error)
 591		set_fs_pwd(current->fs, &fd_file(f)->f_path);
 592	return error;
 593}
 594
 595SYSCALL_DEFINE1(chroot, const char __user *, filename)
 596{
 597	struct path path;
 598	int error;
 599	unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
 600retry:
 601	error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
 602	if (error)
 603		goto out;
 604
 605	error = path_permission(&path, MAY_EXEC | MAY_CHDIR);
 606	if (error)
 607		goto dput_and_out;
 608
 609	error = -EPERM;
 610	if (!ns_capable(current_user_ns(), CAP_SYS_CHROOT))
 611		goto dput_and_out;
 612	error = security_path_chroot(&path);
 613	if (error)
 614		goto dput_and_out;
 615
 616	set_fs_root(current->fs, &path);
 617	error = 0;
 618dput_and_out:
 619	path_put(&path);
 620	if (retry_estale(error, lookup_flags)) {
 621		lookup_flags |= LOOKUP_REVAL;
 622		goto retry;
 623	}
 624out:
 625	return error;
 626}
 627
 628int chmod_common(const struct path *path, umode_t mode)
 629{
 630	struct inode *inode = path->dentry->d_inode;
 631	struct delegated_inode delegated_inode = { };
 632	struct iattr newattrs;
 633	int error;
 634
 635	error = mnt_want_write(path->mnt);
 636	if (error)
 637		return error;
 638retry_deleg:
 639	error = inode_lock_killable(inode);
 640	if (error)
 641		goto out_mnt_unlock;
 642	error = security_path_chmod(path, mode);
 643	if (error)
 644		goto out_unlock;
 645	newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
 646	newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
 647	error = notify_change(mnt_idmap(path->mnt), path->dentry,
 648			      &newattrs, &delegated_inode);
 649out_unlock:
 650	inode_unlock(inode);
 651	if (is_delegated(&delegated_inode)) {
 652		error = break_deleg_wait(&delegated_inode);
 653		if (!error)
 654			goto retry_deleg;
 655	}
 656out_mnt_unlock:
 657	mnt_drop_write(path->mnt);
 658	return error;
 659}
 660
 661int vfs_fchmod(struct file *file, umode_t mode)
 662{
 663	audit_file(file);
 664	return chmod_common(&file->f_path, mode);
 665}
 666
 667SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode)
 668{
 669	CLASS(fd, f)(fd);
 670
 671	if (fd_empty(f))
 672		return -EBADF;
 673
 674	return vfs_fchmod(fd_file(f), mode);
 675}
 676
 677static int do_fchmodat(int dfd, const char __user *filename, umode_t mode,
 678		       unsigned int flags)
 679{
 680	struct path path;
 681	int error;
 682	unsigned int lookup_flags;
 683
 684	if (unlikely(flags & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)))
 685		return -EINVAL;
 686
 687	lookup_flags = (flags & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
 688	if (flags & AT_EMPTY_PATH)
 689		lookup_flags |= LOOKUP_EMPTY;
 690
 691retry:
 692	error = user_path_at(dfd, filename, lookup_flags, &path);
 693	if (!error) {
 694		error = chmod_common(&path, mode);
 695		path_put(&path);
 696		if (retry_estale(error, lookup_flags)) {
 697			lookup_flags |= LOOKUP_REVAL;
 698			goto retry;
 699		}
 700	}
 701	return error;
 702}
 703
 704SYSCALL_DEFINE4(fchmodat2, int, dfd, const char __user *, filename,
 705		umode_t, mode, unsigned int, flags)
 706{
 707	return do_fchmodat(dfd, filename, mode, flags);
 708}
 709
 710SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename,
 711		umode_t, mode)
 712{
 713	return do_fchmodat(dfd, filename, mode, 0);
 714}
 715
 716SYSCALL_DEFINE2(chmod, const char __user *, filename, umode_t, mode)
 717{
 718	return do_fchmodat(AT_FDCWD, filename, mode, 0);
 719}
 720
 721/*
 722 * Check whether @kuid is valid and if so generate and set vfsuid_t in
 723 * ia_vfsuid.
 724 *
 725 * Return: true if @kuid is valid, false if not.
 726 */
 727static inline bool setattr_vfsuid(struct iattr *attr, kuid_t kuid)
 728{
 729	if (!uid_valid(kuid))
 730		return false;
 731	attr->ia_valid |= ATTR_UID;
 732	attr->ia_vfsuid = VFSUIDT_INIT(kuid);
 733	return true;
 734}
 735
 736/*
 737 * Check whether @kgid is valid and if so generate and set vfsgid_t in
 738 * ia_vfsgid.
 739 *
 740 * Return: true if @kgid is valid, false if not.
 741 */
 742static inline bool setattr_vfsgid(struct iattr *attr, kgid_t kgid)
 743{
 744	if (!gid_valid(kgid))
 745		return false;
 746	attr->ia_valid |= ATTR_GID;
 747	attr->ia_vfsgid = VFSGIDT_INIT(kgid);
 748	return true;
 749}
 750
 751int chown_common(const struct path *path, uid_t user, gid_t group)
 752{
 753	struct mnt_idmap *idmap;
 754	struct user_namespace *fs_userns;
 755	struct inode *inode = path->dentry->d_inode;
 756	struct delegated_inode delegated_inode = { };
 757	int error;
 758	struct iattr newattrs;
 759	kuid_t uid;
 760	kgid_t gid;
 761
 762	uid = make_kuid(current_user_ns(), user);
 763	gid = make_kgid(current_user_ns(), group);
 764
 765	idmap = mnt_idmap(path->mnt);
 766	fs_userns = i_user_ns(inode);
 767
 768retry_deleg:
 769	newattrs.ia_vfsuid = INVALID_VFSUID;
 770	newattrs.ia_vfsgid = INVALID_VFSGID;
 771	newattrs.ia_valid =  ATTR_CTIME;
 772	if ((user != (uid_t)-1) && !setattr_vfsuid(&newattrs, uid))
 773		return -EINVAL;
 774	if ((group != (gid_t)-1) && !setattr_vfsgid(&newattrs, gid))
 775		return -EINVAL;
 776	error = inode_lock_killable(inode);
 777	if (error)
 778		return error;
 779	if (!S_ISDIR(inode->i_mode))
 780		newattrs.ia_valid |= ATTR_KILL_SUID | ATTR_KILL_PRIV |
 781				     setattr_should_drop_sgid(idmap, inode);
 782	/* Continue to send actual fs values, not the mount values. */
 783	error = security_path_chown(
 784		path,
 785		from_vfsuid(idmap, fs_userns, newattrs.ia_vfsuid),
 786		from_vfsgid(idmap, fs_userns, newattrs.ia_vfsgid));
 787	if (!error)
 788		error = notify_change(idmap, path->dentry, &newattrs,
 789				      &delegated_inode);
 790	inode_unlock(inode);
 791	if (is_delegated(&delegated_inode)) {
 792		error = break_deleg_wait(&delegated_inode);
 793		if (!error)
 794			goto retry_deleg;
 795	}
 796	return error;
 797}
 798
 799int do_fchownat(int dfd, const char __user *filename, uid_t user, gid_t group,
 800		int flag)
 801{
 802	struct path path;
 803	int error = -EINVAL;
 804	int lookup_flags;
 805
 806	if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
 807		goto out;
 808
 809	lookup_flags = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
 810	if (flag & AT_EMPTY_PATH)
 811		lookup_flags |= LOOKUP_EMPTY;
 812retry:
 813	error = user_path_at(dfd, filename, lookup_flags, &path);
 814	if (error)
 815		goto out;
 816	error = mnt_want_write(path.mnt);
 817	if (error)
 818		goto out_release;
 819	error = chown_common(&path, user, group);
 820	mnt_drop_write(path.mnt);
 821out_release:
 822	path_put(&path);
 823	if (retry_estale(error, lookup_flags)) {
 824		lookup_flags |= LOOKUP_REVAL;
 825		goto retry;
 826	}
 827out:
 828	return error;
 829}
 830
 831SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user,
 832		gid_t, group, int, flag)
 833{
 834	return do_fchownat(dfd, filename, user, group, flag);
 835}
 836
 837SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group)
 838{
 839	return do_fchownat(AT_FDCWD, filename, user, group, 0);
 840}
 841
 842SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group)
 843{
 844	return do_fchownat(AT_FDCWD, filename, user, group,
 845			   AT_SYMLINK_NOFOLLOW);
 846}
 847
 848int vfs_fchown(struct file *file, uid_t user, gid_t group)
 849{
 850	int error;
 851
 852	error = mnt_want_write_file(file);
 853	if (error)
 854		return error;
 855	audit_file(file);
 856	error = chown_common(&file->f_path, user, group);
 857	mnt_drop_write_file(file);
 858	return error;
 859}
 860
 861int ksys_fchown(unsigned int fd, uid_t user, gid_t group)
 862{
 863	CLASS(fd, f)(fd);
 864
 865	if (fd_empty(f))
 866		return -EBADF;
 867
 868	return vfs_fchown(fd_file(f), user, group);
 869}
 870
 871SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group)
 872{
 873	return ksys_fchown(fd, user, group);
 874}
 875
 876static inline int file_get_write_access(struct file *f)
 877{
 878	int error;
 879
 880	error = get_write_access(f->f_inode);
 881	if (unlikely(error))
 882		return error;
 883	error = mnt_get_write_access(f->f_path.mnt);
 884	if (unlikely(error))
 885		goto cleanup_inode;
 886	if (unlikely(f->f_mode & FMODE_BACKING)) {
 887		error = mnt_get_write_access(backing_file_user_path(f)->mnt);
 888		if (unlikely(error))
 889			goto cleanup_mnt;
 890	}
 891	return 0;
 892
 893cleanup_mnt:
 894	mnt_put_write_access(f->f_path.mnt);
 895cleanup_inode:
 896	put_write_access(f->f_inode);
 897	return error;
 898}
 899
 900static int do_dentry_open(struct file *f,
 901			  int (*open)(struct inode *, struct file *))
 902{
 903	static const struct file_operations empty_fops = {};
 904	struct inode *inode = f->f_path.dentry->d_inode;
 905	int error;
 906
 907	path_get(&f->f_path);
 908	f->f_inode = inode;
 909	f->f_mapping = inode->i_mapping;
 910	f->f_wb_err = filemap_sample_wb_err(f->f_mapping);
 911	f->f_sb_err = file_sample_sb_err(f);
 912
 913	if (unlikely(f->f_flags & O_PATH)) {
 914		f->f_mode = FMODE_PATH | FMODE_OPENED;
 915		file_set_fsnotify_mode(f, FMODE_NONOTIFY);
 916		f->f_op = &empty_fops;
 917		return 0;
 918	}
 919
 920	if ((f->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ) {
 921		i_readcount_inc(inode);
 922	} else if (f->f_mode & FMODE_WRITE && !special_file(inode->i_mode)) {
 923		error = file_get_write_access(f);
 924		if (unlikely(error))
 925			goto cleanup_file;
 926		f->f_mode |= FMODE_WRITER;
 927	}
 928
 929	/* POSIX.1-2008/SUSv4 Section XSI 2.9.7 */
 930	if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode))
 931		f->f_mode |= FMODE_ATOMIC_POS;
 932
 933	f->f_op = fops_get(inode->i_fop);
 934	if (WARN_ON(!f->f_op)) {
 935		error = -ENODEV;
 936		goto cleanup_all;
 937	}
 938
 939	error = security_file_open(f);
 940	if (unlikely(error))
 941		goto cleanup_all;
 942
 943	/*
 944	 * Call fsnotify open permission hook and set FMODE_NONOTIFY_* bits
 945	 * according to existing permission watches.
 946	 * If FMODE_NONOTIFY mode was already set for an fanotify fd or for a
 947	 * pseudo file, this call will not change the mode.
 948	 */
 949	error = fsnotify_open_perm_and_set_mode(f);
 950	if (unlikely(error))
 951		goto cleanup_all;
 952
 953	error = break_lease(file_inode(f), f->f_flags);
 954	if (unlikely(error))
 955		goto cleanup_all;
 956
 957	/* normally all 3 are set; ->open() can clear them if needed */
 958	f->f_mode |= FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE;
 959	if (!open)
 960		open = f->f_op->open;
 961	if (open) {
 962		error = open(inode, f);
 963		if (error)
 964			goto cleanup_all;
 965	}
 966	f->f_mode |= FMODE_OPENED;
 967	if ((f->f_mode & FMODE_READ) &&
 968	     likely(f->f_op->read || f->f_op->read_iter))
 969		f->f_mode |= FMODE_CAN_READ;
 970	if ((f->f_mode & FMODE_WRITE) &&
 971	     likely(f->f_op->write || f->f_op->write_iter))
 972		f->f_mode |= FMODE_CAN_WRITE;
 973	if ((f->f_mode & FMODE_LSEEK) && !f->f_op->llseek)
 974		f->f_mode &= ~FMODE_LSEEK;
 975	if (f->f_mapping->a_ops && f->f_mapping->a_ops->direct_IO)
 976		f->f_mode |= FMODE_CAN_ODIRECT;
 977
 978	f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
 979	f->f_iocb_flags = iocb_flags(f);
 980
 981	file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);
 982
 983	if ((f->f_flags & O_DIRECT) && !(f->f_mode & FMODE_CAN_ODIRECT))
 984		return -EINVAL;
 985
 986	/*
 987	 * XXX: Huge page cache doesn't support writing yet. Drop all page
 988	 * cache for this file before processing writes.
 989	 */
 990	if (f->f_mode & FMODE_WRITE) {
 991		/*
 992		 * Depends on full fence from get_write_access() to synchronize
 993		 * against collapse_file() regarding i_writecount and nr_thps
 994		 * updates. Ensures subsequent insertion of THPs into the page
 995		 * cache will fail.
 996		 */
 997		if (filemap_nr_thps(inode->i_mapping)) {
 998			struct address_space *mapping = inode->i_mapping;
 999
1000			filemap_invalidate_lock(inode->i_mapping);
1001			/*
1002			 * unmap_mapping_range just need to be called once
1003			 * here, because the private pages is not need to be
1004			 * unmapped mapping (e.g. data segment of dynamic
1005			 * shared libraries here).
1006			 */
1007			unmap_mapping_range(mapping, 0, 0, 0);
1008			truncate_inode_pages(mapping, 0);
1009			filemap_invalidate_unlock(inode->i_mapping);
1010		}
1011	}
1012
1013	return 0;
1014
1015cleanup_all:
1016	if (WARN_ON_ONCE(error > 0))
1017		error = -EINVAL;
1018	fops_put(f->f_op);
1019	put_file_access(f);
1020cleanup_file:
1021	path_put(&f->f_path);
1022	f->__f_path.mnt = NULL;
1023	f->__f_path.dentry = NULL;
1024	f->f_inode = NULL;
1025	return error;
1026}
1027
1028/**
1029 * finish_open - finish opening a file
1030 * @file: file pointer
1031 * @dentry: pointer to dentry
1032 * @open: open callback
1033 *
1034 * This can be used to finish opening a file passed to i_op->atomic_open().
1035 *
1036 * If the open callback is set to NULL, then the standard f_op->open()
1037 * filesystem callback is substituted.
1038 *
1039 * NB: the dentry reference is _not_ consumed.  If, for example, the dentry is
1040 * the return value of d_splice_alias(), then the caller needs to perform dput()
1041 * on it after finish_open().
1042 *
1043 * Returns zero on success or -errno if the open failed.
1044 */
1045int finish_open(struct file *file, struct dentry *dentry,
1046		int (*open)(struct inode *, struct file *))
1047{
1048	BUG_ON(file->f_mode & FMODE_OPENED); /* once it's opened, it's opened */
1049
1050	file->__f_path.dentry = dentry;
1051	return do_dentry_open(file, open);
1052}
1053EXPORT_SYMBOL(finish_open);
1054
1055/**
1056 * finish_no_open - finish ->atomic_open() without opening the file
1057 *
1058 * @file: file pointer
1059 * @dentry: dentry, ERR_PTR(-E...) or NULL (as returned from ->lookup())
1060 *
1061 * This can be used to set the result of a lookup in ->atomic_open().
1062 *
1063 * NB: unlike finish_open() this function does consume the dentry reference and
1064 * the caller need not dput() it.
1065 *
1066 * Returns 0 or -E..., which must be the return value of ->atomic_open() after
1067 * having called this function.
1068 */
1069int finish_no_open(struct file *file, struct dentry *dentry)
1070{
1071	if (IS_ERR(dentry))
1072		return PTR_ERR(dentry);
1073	file->__f_path.dentry = dentry;
1074	return 0;
1075}
1076EXPORT_SYMBOL(finish_no_open);
1077
1078char *file_path(struct file *filp, char *buf, int buflen)
1079{
1080	return d_path(&filp->f_path, buf, buflen);
1081}
1082EXPORT_SYMBOL(file_path);
1083
1084/**
1085 * vfs_open - open the file at the given path
1086 * @path: path to open
1087 * @file: newly allocated file with f_flag initialized
1088 */
1089int vfs_open(const struct path *path, struct file *file)
1090{
1091	int ret;
1092
1093	file->__f_path = *path;
1094	ret = do_dentry_open(file, NULL);
1095	if (!ret) {
1096		/*
1097		 * Once we return a file with FMODE_OPENED, __fput() will call
1098		 * fsnotify_close(), so we need fsnotify_open() here for
1099		 * symmetry.
1100		 */
1101		fsnotify_open(file);
1102	}
1103	return ret;
1104}
1105
1106struct file *dentry_open(const struct path *path, int flags,
1107			 const struct cred *cred)
1108{
1109	int error;
1110	struct file *f;
1111
1112	/* We must always pass in a valid mount pointer. */
1113	BUG_ON(!path->mnt);
1114
1115	f = alloc_empty_file(flags, cred);
1116	if (!IS_ERR(f)) {
1117		error = vfs_open(path, f);
1118		if (error) {
1119			fput(f);
1120			f = ERR_PTR(error);
1121		}
1122	}
1123	return f;
1124}
1125EXPORT_SYMBOL(dentry_open);
1126
1127struct file *dentry_open_nonotify(const struct path *path, int flags,
1128				  const struct cred *cred)
1129{
1130	struct file *f = alloc_empty_file(flags, cred);
1131	if (!IS_ERR(f)) {
1132		int error;
1133
1134		file_set_fsnotify_mode(f, FMODE_NONOTIFY);
1135		error = vfs_open(path, f);
1136		if (error) {
1137			fput(f);
1138			f = ERR_PTR(error);
1139		}
1140	}
1141	return f;
1142}
1143
1144/**
1145 * dentry_create - Create and open a file
1146 * @path: path to create
1147 * @flags: O_ flags
1148 * @mode: mode bits for new file
1149 * @cred: credentials to use
1150 *
1151 * Caller must hold the parent directory's lock, and have prepared
1152 * a negative dentry, placed in @path->dentry, for the new file.
1153 *
1154 * Caller sets @path->mnt to the vfsmount of the filesystem where
1155 * the new file is to be created. The parent directory and the
1156 * negative dentry must reside on the same filesystem instance.
1157 *
1158 * On success, returns a "struct file *". Otherwise a ERR_PTR
1159 * is returned.
1160 */
1161struct file *dentry_create(const struct path *path, int flags, umode_t mode,
1162			   const struct cred *cred)
1163{
1164	struct file *f;
1165	int error;
1166
1167	f = alloc_empty_file(flags, cred);
1168	if (IS_ERR(f))
1169		return f;
1170
1171	error = vfs_create(mnt_idmap(path->mnt), path->dentry, mode, NULL);
1172	if (!error)
1173		error = vfs_open(path, f);
1174
1175	if (unlikely(error)) {
1176		fput(f);
1177		return ERR_PTR(error);
1178	}
1179	return f;
1180}
1181EXPORT_SYMBOL(dentry_create);
1182
1183/**
1184 * kernel_file_open - open a file for kernel internal use
1185 * @path:	path of the file to open
1186 * @flags:	open flags
1187 * @cred:	credentials for open
1188 *
1189 * Open a file for use by in-kernel consumers. The file is not accounted
1190 * against nr_files and must not be installed into the file descriptor
1191 * table.
1192 *
1193 * Return: Opened file on success, an error pointer on failure.
1194 */
1195struct file *kernel_file_open(const struct path *path, int flags,
1196				const struct cred *cred)
1197{
1198	struct file *f;
1199	int error;
1200
1201	f = alloc_empty_file_noaccount(flags, cred);
1202	if (IS_ERR(f))
1203		return f;
1204
1205	error = vfs_open(path, f);
1206	if (error) {
1207		fput(f);
1208		return ERR_PTR(error);
1209	}
1210	return f;
1211}
1212EXPORT_SYMBOL_GPL(kernel_file_open);
1213
1214#define WILL_CREATE(flags)	(flags & (O_CREAT | __O_TMPFILE))
1215#define O_PATH_FLAGS		(O_DIRECTORY | O_NOFOLLOW | O_PATH | O_CLOEXEC)
1216
1217inline struct open_how build_open_how(int flags, umode_t mode)
1218{
1219	struct open_how how = {
1220		.flags = flags & VALID_OPEN_FLAGS,
1221		.mode = mode & S_IALLUGO,
1222	};
1223
1224	/* O_PATH beats everything else. */
1225	if (how.flags & O_PATH)
1226		how.flags &= O_PATH_FLAGS;
1227	/* Modes should only be set for create-like flags. */
1228	if (!WILL_CREATE(how.flags))
1229		how.mode = 0;
1230	return how;
1231}
1232
1233inline int build_open_flags(const struct open_how *how, struct open_flags *op)
1234{
1235	u64 flags = how->flags;
1236	u64 strip = O_CLOEXEC;
1237	int lookup_flags = 0;
1238	int acc_mode = ACC_MODE(flags);
1239
1240	BUILD_BUG_ON_MSG(upper_32_bits(VALID_OPEN_FLAGS),
1241			 "struct open_flags doesn't yet handle flags > 32 bits");
1242
1243	/*
1244	 * Strip flags that aren't relevant in determining struct open_flags.
1245	 */
1246	flags &= ~strip;
1247
1248	/*
1249	 * Older syscalls implicitly clear all of the invalid flags or argument
1250	 * values before calling build_open_flags(), but openat2(2) checks all
1251	 * of its arguments.
1252	 */
1253	if (flags & ~VALID_OPEN_FLAGS)
1254		return -EINVAL;
1255	if (how->resolve & ~VALID_RESOLVE_FLAGS)
1256		return -EINVAL;
1257
1258	/* Scoping flags are mutually exclusive. */
1259	if ((how->resolve & RESOLVE_BENEATH) && (how->resolve & RESOLVE_IN_ROOT))
1260		return -EINVAL;
1261
1262	/* Deal with the mode. */
1263	if (WILL_CREATE(flags)) {
1264		if (how->mode & ~S_IALLUGO)
1265			return -EINVAL;
1266		op->mode = how->mode | S_IFREG;
1267	} else {
1268		if (how->mode != 0)
1269			return -EINVAL;
1270		op->mode = 0;
1271	}
1272
1273	/*
1274	 * Block bugs where O_DIRECTORY | O_CREAT created regular files.
1275	 * Note, that blocking O_DIRECTORY | O_CREAT here also protects
1276	 * O_TMPFILE below which requires O_DIRECTORY being raised.
1277	 */
1278	if ((flags & (O_DIRECTORY | O_CREAT)) == (O_DIRECTORY | O_CREAT))
1279		return -EINVAL;
1280
1281	/* Now handle the creative implementation of O_TMPFILE. */
1282	if (flags & __O_TMPFILE) {
1283		/*
1284		 * In order to ensure programs get explicit errors when trying
1285		 * to use O_TMPFILE on old kernels we enforce that O_DIRECTORY
1286		 * is raised alongside __O_TMPFILE.
1287		 */
1288		if (!(flags & O_DIRECTORY))
1289			return -EINVAL;
1290		if (!(acc_mode & MAY_WRITE))
1291			return -EINVAL;
1292	}
1293	if (flags & O_PATH) {
1294		/* O_PATH only permits certain other flags to be set. */
1295		if (flags & ~O_PATH_FLAGS)
1296			return -EINVAL;
1297		acc_mode = 0;
1298	}
1299
1300	/*
1301	 * O_SYNC is implemented as __O_SYNC|O_DSYNC.  As many places only
1302	 * check for O_DSYNC if the need any syncing at all we enforce it's
1303	 * always set instead of having to deal with possibly weird behaviour
1304	 * for malicious applications setting only __O_SYNC.
1305	 */
1306	if (flags & __O_SYNC)
1307		flags |= O_DSYNC;
1308
1309	op->open_flag = flags;
1310
1311	/* O_TRUNC implies we need access checks for write permissions */
1312	if (flags & O_TRUNC)
1313		acc_mode |= MAY_WRITE;
1314
1315	/* Allow the LSM permission hook to distinguish append
1316	   access from general write access. */
1317	if (flags & O_APPEND)
1318		acc_mode |= MAY_APPEND;
1319
1320	op->acc_mode = acc_mode;
1321
1322	op->intent = flags & O_PATH ? 0 : LOOKUP_OPEN;
1323
1324	if (flags & O_CREAT) {
1325		op->intent |= LOOKUP_CREATE;
1326		if (flags & O_EXCL) {
1327			op->intent |= LOOKUP_EXCL;
1328			flags |= O_NOFOLLOW;
1329		}
1330	}
1331
1332	if (flags & O_DIRECTORY)
1333		lookup_flags |= LOOKUP_DIRECTORY;
1334	if (!(flags & O_NOFOLLOW))
1335		lookup_flags |= LOOKUP_FOLLOW;
1336
1337	if (how->resolve & RESOLVE_NO_XDEV)
1338		lookup_flags |= LOOKUP_NO_XDEV;
1339	if (how->resolve & RESOLVE_NO_MAGICLINKS)
1340		lookup_flags |= LOOKUP_NO_MAGICLINKS;
1341	if (how->resolve & RESOLVE_NO_SYMLINKS)
1342		lookup_flags |= LOOKUP_NO_SYMLINKS;
1343	if (how->resolve & RESOLVE_BENEATH)
1344		lookup_flags |= LOOKUP_BENEATH;
1345	if (how->resolve & RESOLVE_IN_ROOT)
1346		lookup_flags |= LOOKUP_IN_ROOT;
1347	if (how->resolve & RESOLVE_CACHED) {
1348		/* Don't bother even trying for create/truncate/tmpfile open */
1349		if (flags & (O_TRUNC | O_CREAT | __O_TMPFILE))
1350			return -EAGAIN;
1351		lookup_flags |= LOOKUP_CACHED;
1352	}
1353
1354	op->lookup_flags = lookup_flags;
1355	return 0;
1356}
1357
1358/**
1359 * file_open_name - open file and return file pointer
1360 *
1361 * @name:	struct filename containing path to open
1362 * @flags:	open flags as per the open(2) second argument
1363 * @mode:	mode for the new file if O_CREAT is set, else ignored
1364 *
1365 * This is the helper to open a file from kernelspace if you really
1366 * have to.  But in generally you should not do this, so please move
1367 * along, nothing to see here..
1368 */
1369struct file *file_open_name(struct filename *name, int flags, umode_t mode)
1370{
1371	struct open_flags op;
1372	struct open_how how = build_open_how(flags, mode);
1373	int err = build_open_flags(&how, &op);
1374	if (err)
1375		return ERR_PTR(err);
1376	return do_filp_open(AT_FDCWD, name, &op);
1377}
1378
1379/**
1380 * filp_open - open file and return file pointer
1381 *
1382 * @filename:	path to open
1383 * @flags:	open flags as per the open(2) second argument
1384 * @mode:	mode for the new file if O_CREAT is set, else ignored
1385 *
1386 * This is the helper to open a file from kernelspace if you really
1387 * have to.  But in generally you should not do this, so please move
1388 * along, nothing to see here..
1389 */
1390struct file *filp_open(const char *filename, int flags, umode_t mode)
1391{
1392	struct filename *name = getname_kernel(filename);
1393	struct file *file = ERR_CAST(name);
1394
1395	if (!IS_ERR(name)) {
1396		file = file_open_name(name, flags, mode);
1397		putname(name);
1398	}
1399	return file;
1400}
1401EXPORT_SYMBOL(filp_open);
1402
1403struct file *file_open_root(const struct path *root,
1404			    const char *filename, int flags, umode_t mode)
1405{
1406	struct open_flags op;
1407	struct open_how how = build_open_how(flags, mode);
1408	int err = build_open_flags(&how, &op);
1409	if (err)
1410		return ERR_PTR(err);
1411	return do_file_open_root(root, filename, &op);
1412}
1413EXPORT_SYMBOL(file_open_root);
1414
1415static int do_sys_openat2(int dfd, const char __user *filename,
1416			  struct open_how *how)
1417{
1418	struct open_flags op;
1419	struct filename *tmp __free(putname) = NULL;
1420	int err;
1421
1422	err = build_open_flags(how, &op);
1423	if (unlikely(err))
1424		return err;
1425
1426	tmp = getname(filename);
1427	if (IS_ERR(tmp))
1428		return PTR_ERR(tmp);
1429
1430	return FD_ADD(how->flags, do_filp_open(dfd, tmp, &op));
1431}
1432
1433int do_sys_open(int dfd, const char __user *filename, int flags, umode_t mode)
1434{
1435	struct open_how how = build_open_how(flags, mode);
1436	return do_sys_openat2(dfd, filename, &how);
1437}
1438
1439
1440SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)
1441{
1442	if (force_o_largefile())
1443		flags |= O_LARGEFILE;
1444	return do_sys_open(AT_FDCWD, filename, flags, mode);
1445}
1446
1447SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags,
1448		umode_t, mode)
1449{
1450	if (force_o_largefile())
1451		flags |= O_LARGEFILE;
1452	return do_sys_open(dfd, filename, flags, mode);
1453}
1454
1455SYSCALL_DEFINE4(openat2, int, dfd, const char __user *, filename,
1456		struct open_how __user *, how, size_t, usize)
1457{
1458	int err;
1459	struct open_how tmp;
1460
1461	BUILD_BUG_ON(sizeof(struct open_how) < OPEN_HOW_SIZE_VER0);
1462	BUILD_BUG_ON(sizeof(struct open_how) != OPEN_HOW_SIZE_LATEST);
1463
1464	if (unlikely(usize < OPEN_HOW_SIZE_VER0))
1465		return -EINVAL;
1466	if (unlikely(usize > PAGE_SIZE))
1467		return -E2BIG;
1468
1469	err = copy_struct_from_user(&tmp, sizeof(tmp), how, usize);
1470	if (err)
1471		return err;
1472
1473	audit_openat2_how(&tmp);
1474
1475	/* O_LARGEFILE is only allowed for non-O_PATH. */
1476	if (!(tmp.flags & O_PATH) && force_o_largefile())
1477		tmp.flags |= O_LARGEFILE;
1478
1479	return do_sys_openat2(dfd, filename, &tmp);
1480}
1481
1482#ifdef CONFIG_COMPAT
1483/*
1484 * Exactly like sys_open(), except that it doesn't set the
1485 * O_LARGEFILE flag.
1486 */
1487COMPAT_SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)
1488{
1489	return do_sys_open(AT_FDCWD, filename, flags, mode);
1490}
1491
1492/*
1493 * Exactly like sys_openat(), except that it doesn't set the
1494 * O_LARGEFILE flag.
1495 */
1496COMPAT_SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags, umode_t, mode)
1497{
1498	return do_sys_open(dfd, filename, flags, mode);
1499}
1500#endif
1501
1502#ifndef __alpha__
1503
1504/*
1505 * For backward compatibility?  Maybe this should be moved
1506 * into arch/i386 instead?
1507 */
1508SYSCALL_DEFINE2(creat, const char __user *, pathname, umode_t, mode)
1509{
1510	int flags = O_CREAT | O_WRONLY | O_TRUNC;
1511
1512	if (force_o_largefile())
1513		flags |= O_LARGEFILE;
1514	return do_sys_open(AT_FDCWD, pathname, flags, mode);
1515}
1516#endif
1517
1518/*
1519 * "id" is the POSIX thread ID. We use the
1520 * files pointer for this..
1521 */
1522static int filp_flush(struct file *filp, fl_owner_t id)
1523{
1524	int retval = 0;
1525
1526	if (CHECK_DATA_CORRUPTION(file_count(filp) == 0, filp,
1527			"VFS: Close: file count is 0 (f_op=%ps)",
1528			filp->f_op)) {
1529		return 0;
1530	}
1531
1532	if (filp->f_op->flush)
1533		retval = filp->f_op->flush(filp, id);
1534
1535	if (likely(!(filp->f_mode & FMODE_PATH))) {
1536		dnotify_flush(filp, id);
1537		locks_remove_posix(filp, id);
1538	}
1539	return retval;
1540}
1541
1542int filp_close(struct file *filp, fl_owner_t id)
1543{
1544	int retval;
1545
1546	retval = filp_flush(filp, id);
1547	fput_close(filp);
1548
1549	return retval;
1550}
1551EXPORT_SYMBOL(filp_close);
1552
1553/*
1554 * Careful here! We test whether the file pointer is NULL before
1555 * releasing the fd. This ensures that one clone task can't release
1556 * an fd while another clone is opening it.
1557 */
1558SYSCALL_DEFINE1(close, unsigned int, fd)
1559{
1560	int retval;
1561	struct file *file;
1562
1563	file = file_close_fd(fd);
1564	if (!file)
1565		return -EBADF;
1566
1567	retval = filp_flush(file, current->files);
1568
1569	/*
1570	 * We're returning to user space. Don't bother
1571	 * with any delayed fput() cases.
1572	 */
1573	fput_close_sync(file);
1574
1575	if (likely(retval == 0))
1576		return 0;
1577
1578	/* can't restart close syscall because file table entry was cleared */
1579	if (retval == -ERESTARTSYS ||
1580	    retval == -ERESTARTNOINTR ||
1581	    retval == -ERESTARTNOHAND ||
1582	    retval == -ERESTART_RESTARTBLOCK)
1583		retval = -EINTR;
1584
1585	return retval;
1586}
1587
1588/*
1589 * This routine simulates a hangup on the tty, to arrange that users
1590 * are given clean terminals at login time.
1591 */
1592SYSCALL_DEFINE0(vhangup)
1593{
1594	if (capable(CAP_SYS_TTY_CONFIG)) {
1595		tty_vhangup_self();
1596		return 0;
1597	}
1598	return -EPERM;
1599}
1600
1601/*
1602 * Called when an inode is about to be open.
1603 * We use this to disallow opening large files on 32bit systems if
1604 * the caller didn't specify O_LARGEFILE.  On 64bit systems we force
1605 * on this flag in sys_open.
1606 */
1607int generic_file_open(struct inode * inode, struct file * filp)
1608{
1609	if (!(filp->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS)
1610		return -EOVERFLOW;
1611	return 0;
1612}
1613
1614EXPORT_SYMBOL(generic_file_open);
1615
1616/*
1617 * This is used by subsystems that don't want seekable
1618 * file descriptors. The function is not supposed to ever fail, the only
1619 * reason it returns an 'int' and not 'void' is so that it can be plugged
1620 * directly into file_operations structure.
1621 */
1622int nonseekable_open(struct inode *inode, struct file *filp)
1623{
1624	filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);
1625	return 0;
1626}
1627
1628EXPORT_SYMBOL(nonseekable_open);
1629
1630/*
1631 * stream_open is used by subsystems that want stream-like file descriptors.
1632 * Such file descriptors are not seekable and don't have notion of position
1633 * (file.f_pos is always 0 and ppos passed to .read()/.write() is always NULL).
1634 * Contrary to file descriptors of other regular files, .read() and .write()
1635 * can run simultaneously.
1636 *
1637 * stream_open never fails and is marked to return int so that it could be
1638 * directly used as file_operations.open .
1639 */
1640int stream_open(struct inode *inode, struct file *filp)
1641{
1642	filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE | FMODE_ATOMIC_POS);
1643	filp->f_mode |= FMODE_STREAM;
1644	return 0;
1645}
1646
1647EXPORT_SYMBOL(stream_open);