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v6.2
   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#include <linux/mnt_idmapping.h>
  36
  37#include "internal.h"
  38
  39int do_truncate(struct user_namespace *mnt_userns, 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(mnt_userns, dentry);
  58	if (ret < 0)
  59		return ret;
  60	if (ret)
  61		newattrs.ia_valid |= ret | ATTR_FORCE;
  62
  63	inode_lock(dentry->d_inode);
  64	/* Note any delegations or leases have already been broken: */
  65	ret = notify_change(mnt_userns, dentry, &newattrs, NULL);
  66	inode_unlock(dentry->d_inode);
  67	return ret;
  68}
  69
  70long vfs_truncate(const struct path *path, loff_t length)
  71{
  72	struct user_namespace *mnt_userns;
  73	struct inode *inode;
  74	long error;
  75
  76	inode = path->dentry->d_inode;
  77
  78	/* For directories it's -EISDIR, for other non-regulars - -EINVAL */
  79	if (S_ISDIR(inode->i_mode))
  80		return -EISDIR;
  81	if (!S_ISREG(inode->i_mode))
  82		return -EINVAL;
  83
  84	error = mnt_want_write(path->mnt);
  85	if (error)
  86		goto out;
  87
  88	mnt_userns = mnt_user_ns(path->mnt);
  89	error = inode_permission(mnt_userns, inode, MAY_WRITE);
  90	if (error)
  91		goto mnt_drop_write_and_out;
  92
  93	error = -EPERM;
  94	if (IS_APPEND(inode))
  95		goto mnt_drop_write_and_out;
  96
  97	error = get_write_access(inode);
  98	if (error)
  99		goto mnt_drop_write_and_out;
 100
 101	/*
 102	 * Make sure that there are no leases.  get_write_access() protects
 103	 * against the truncate racing with a lease-granting setlease().
 104	 */
 105	error = break_lease(inode, O_WRONLY);
 106	if (error)
 107		goto put_write_and_out;
 108
 109	error = security_path_truncate(path);
 110	if (!error)
 111		error = do_truncate(mnt_userns, path->dentry, length, 0, NULL);
 
 
 112
 113put_write_and_out:
 114	put_write_access(inode);
 115mnt_drop_write_and_out:
 116	mnt_drop_write(path->mnt);
 117out:
 118	return error;
 119}
 120EXPORT_SYMBOL_GPL(vfs_truncate);
 121
 122long do_sys_truncate(const char __user *pathname, loff_t length)
 123{
 124	unsigned int lookup_flags = LOOKUP_FOLLOW;
 125	struct path path;
 126	int error;
 127
 128	if (length < 0)	/* sorry, but loff_t says... */
 129		return -EINVAL;
 130
 131retry:
 132	error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
 133	if (!error) {
 134		error = vfs_truncate(&path, length);
 135		path_put(&path);
 136	}
 137	if (retry_estale(error, lookup_flags)) {
 138		lookup_flags |= LOOKUP_REVAL;
 139		goto retry;
 140	}
 141	return error;
 142}
 143
 144SYSCALL_DEFINE2(truncate, const char __user *, path, long, length)
 145{
 146	return do_sys_truncate(path, length);
 147}
 148
 149#ifdef CONFIG_COMPAT
 150COMPAT_SYSCALL_DEFINE2(truncate, const char __user *, path, compat_off_t, length)
 151{
 152	return do_sys_truncate(path, length);
 153}
 154#endif
 155
 156long do_sys_ftruncate(unsigned int fd, loff_t length, int small)
 157{
 158	struct inode *inode;
 159	struct dentry *dentry;
 160	struct fd f;
 161	int error;
 162
 163	error = -EINVAL;
 164	if (length < 0)
 165		goto out;
 166	error = -EBADF;
 167	f = fdget(fd);
 168	if (!f.file)
 169		goto out;
 170
 171	/* explicitly opened as large or we are on 64-bit box */
 172	if (f.file->f_flags & O_LARGEFILE)
 173		small = 0;
 174
 175	dentry = f.file->f_path.dentry;
 176	inode = dentry->d_inode;
 177	error = -EINVAL;
 178	if (!S_ISREG(inode->i_mode) || !(f.file->f_mode & FMODE_WRITE))
 179		goto out_putf;
 180
 181	error = -EINVAL;
 182	/* Cannot ftruncate over 2^31 bytes without large file support */
 183	if (small && length > MAX_NON_LFS)
 184		goto out_putf;
 185
 186	error = -EPERM;
 187	/* Check IS_APPEND on real upper inode */
 188	if (IS_APPEND(file_inode(f.file)))
 189		goto out_putf;
 
 190	sb_start_write(inode->i_sb);
 191	error = security_file_truncate(f.file);
 192	if (!error)
 193		error = do_truncate(file_mnt_user_ns(f.file), dentry, length,
 194				    ATTR_MTIME | ATTR_CTIME, f.file);
 
 195	sb_end_write(inode->i_sb);
 196out_putf:
 197	fdput(f);
 198out:
 199	return error;
 200}
 201
 202SYSCALL_DEFINE2(ftruncate, unsigned int, fd, unsigned long, length)
 203{
 204	return do_sys_ftruncate(fd, length, 1);
 205}
 206
 207#ifdef CONFIG_COMPAT
 208COMPAT_SYSCALL_DEFINE2(ftruncate, unsigned int, fd, compat_ulong_t, length)
 209{
 210	return do_sys_ftruncate(fd, length, 1);
 211}
 212#endif
 213
 214/* LFS versions of truncate are only needed on 32 bit machines */
 215#if BITS_PER_LONG == 32
 216SYSCALL_DEFINE2(truncate64, const char __user *, path, loff_t, length)
 217{
 218	return do_sys_truncate(path, length);
 219}
 220
 221SYSCALL_DEFINE2(ftruncate64, unsigned int, fd, loff_t, length)
 222{
 223	return do_sys_ftruncate(fd, length, 0);
 224}
 225#endif /* BITS_PER_LONG == 32 */
 226
 227#if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_TRUNCATE64)
 228COMPAT_SYSCALL_DEFINE3(truncate64, const char __user *, pathname,
 229		       compat_arg_u64_dual(length))
 230{
 231	return ksys_truncate(pathname, compat_arg_u64_glue(length));
 232}
 233#endif
 234
 235#if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_FTRUNCATE64)
 236COMPAT_SYSCALL_DEFINE3(ftruncate64, unsigned int, fd,
 237		       compat_arg_u64_dual(length))
 238{
 239	return ksys_ftruncate(fd, compat_arg_u64_glue(length));
 240}
 241#endif
 242
 243int vfs_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
 244{
 245	struct inode *inode = file_inode(file);
 246	long ret;
 247
 248	if (offset < 0 || len <= 0)
 249		return -EINVAL;
 250
 251	/* Return error if mode is not supported */
 252	if (mode & ~FALLOC_FL_SUPPORTED_MASK)
 253		return -EOPNOTSUPP;
 254
 255	/* Punch hole and zero range are mutually exclusive */
 256	if ((mode & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE)) ==
 257	    (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE))
 258		return -EOPNOTSUPP;
 259
 260	/* Punch hole must have keep size set */
 261	if ((mode & FALLOC_FL_PUNCH_HOLE) &&
 262	    !(mode & FALLOC_FL_KEEP_SIZE))
 263		return -EOPNOTSUPP;
 264
 265	/* Collapse range should only be used exclusively. */
 266	if ((mode & FALLOC_FL_COLLAPSE_RANGE) &&
 267	    (mode & ~FALLOC_FL_COLLAPSE_RANGE))
 268		return -EINVAL;
 269
 270	/* Insert range should only be used exclusively. */
 271	if ((mode & FALLOC_FL_INSERT_RANGE) &&
 272	    (mode & ~FALLOC_FL_INSERT_RANGE))
 273		return -EINVAL;
 274
 275	/* Unshare range should only be used with allocate mode. */
 276	if ((mode & FALLOC_FL_UNSHARE_RANGE) &&
 277	    (mode & ~(FALLOC_FL_UNSHARE_RANGE | FALLOC_FL_KEEP_SIZE)))
 278		return -EINVAL;
 279
 280	if (!(file->f_mode & FMODE_WRITE))
 281		return -EBADF;
 282
 283	/*
 284	 * We can only allow pure fallocate on append only files
 285	 */
 286	if ((mode & ~FALLOC_FL_KEEP_SIZE) && IS_APPEND(inode))
 287		return -EPERM;
 288
 289	if (IS_IMMUTABLE(inode))
 290		return -EPERM;
 291
 292	/*
 293	 * We cannot allow any fallocate operation on an active swapfile
 294	 */
 295	if (IS_SWAPFILE(inode))
 296		return -ETXTBSY;
 297
 298	/*
 299	 * Revalidate the write permissions, in case security policy has
 300	 * changed since the files were opened.
 301	 */
 302	ret = security_file_permission(file, MAY_WRITE);
 303	if (ret)
 304		return ret;
 305
 306	if (S_ISFIFO(inode->i_mode))
 307		return -ESPIPE;
 308
 309	if (S_ISDIR(inode->i_mode))
 310		return -EISDIR;
 311
 312	if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
 313		return -ENODEV;
 314
 315	/* Check for wrap through zero too */
 316	if (((offset + len) > inode->i_sb->s_maxbytes) || ((offset + len) < 0))
 317		return -EFBIG;
 318
 319	if (!file->f_op->fallocate)
 320		return -EOPNOTSUPP;
 321
 322	file_start_write(file);
 323	ret = file->f_op->fallocate(file, mode, offset, len);
 324
 325	/*
 326	 * Create inotify and fanotify events.
 327	 *
 328	 * To keep the logic simple always create events if fallocate succeeds.
 329	 * This implies that events are even created if the file size remains
 330	 * unchanged, e.g. when using flag FALLOC_FL_KEEP_SIZE.
 331	 */
 332	if (ret == 0)
 333		fsnotify_modify(file);
 334
 335	file_end_write(file);
 336	return ret;
 337}
 338EXPORT_SYMBOL_GPL(vfs_fallocate);
 339
 340int ksys_fallocate(int fd, int mode, loff_t offset, loff_t len)
 341{
 342	struct fd f = fdget(fd);
 343	int error = -EBADF;
 344
 345	if (f.file) {
 346		error = vfs_fallocate(f.file, mode, offset, len);
 347		fdput(f);
 348	}
 349	return error;
 350}
 351
 352SYSCALL_DEFINE4(fallocate, int, fd, int, mode, loff_t, offset, loff_t, len)
 353{
 354	return ksys_fallocate(fd, mode, offset, len);
 355}
 356
 357#if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_FALLOCATE)
 358COMPAT_SYSCALL_DEFINE6(fallocate, int, fd, int, mode, compat_arg_u64_dual(offset),
 359		       compat_arg_u64_dual(len))
 360{
 361	return ksys_fallocate(fd, mode, compat_arg_u64_glue(offset),
 362			      compat_arg_u64_glue(len));
 363}
 364#endif
 365
 366/*
 367 * access() needs to use the real uid/gid, not the effective uid/gid.
 368 * We do this by temporarily clearing all FS-related capabilities and
 369 * switching the fsuid/fsgid around to the real ones.
 370 */
 371static const struct cred *access_override_creds(void)
 372{
 373	const struct cred *old_cred;
 374	struct cred *override_cred;
 
 
 
 
 
 
 
 375
 376	override_cred = prepare_creds();
 377	if (!override_cred)
 378		return NULL;
 379
 380	override_cred->fsuid = override_cred->uid;
 381	override_cred->fsgid = override_cred->gid;
 382
 383	if (!issecure(SECURE_NO_SETUID_FIXUP)) {
 384		/* Clear the capabilities if we switch to a non-root user */
 385		kuid_t root_uid = make_kuid(override_cred->user_ns, 0);
 386		if (!uid_eq(override_cred->uid, root_uid))
 387			cap_clear(override_cred->cap_effective);
 388		else
 389			override_cred->cap_effective =
 390				override_cred->cap_permitted;
 391	}
 392
 393	/*
 394	 * The new set of credentials can *only* be used in
 395	 * task-synchronous circumstances, and does not need
 396	 * RCU freeing, unless somebody then takes a separate
 397	 * reference to it.
 398	 *
 399	 * NOTE! This is _only_ true because this credential
 400	 * is used purely for override_creds() that installs
 401	 * it as the subjective cred. Other threads will be
 402	 * accessing ->real_cred, not the subjective cred.
 403	 *
 404	 * If somebody _does_ make a copy of this (using the
 405	 * 'get_current_cred()' function), that will clear the
 406	 * non_rcu field, because now that other user may be
 407	 * expecting RCU freeing. But normal thread-synchronous
 408	 * cred accesses will keep things non-RCY.
 409	 */
 410	override_cred->non_rcu = 1;
 411
 412	old_cred = override_creds(override_cred);
 413
 414	/* override_cred() gets its own ref */
 415	put_cred(override_cred);
 416
 417	return old_cred;
 418}
 419
 420static long do_faccessat(int dfd, const char __user *filename, int mode, int flags)
 421{
 422	struct path path;
 423	struct inode *inode;
 424	int res;
 425	unsigned int lookup_flags = LOOKUP_FOLLOW;
 426	const struct cred *old_cred = NULL;
 427
 428	if (mode & ~S_IRWXO)	/* where's F_OK, X_OK, W_OK, R_OK? */
 429		return -EINVAL;
 430
 431	if (flags & ~(AT_EACCESS | AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH))
 432		return -EINVAL;
 433
 434	if (flags & AT_SYMLINK_NOFOLLOW)
 435		lookup_flags &= ~LOOKUP_FOLLOW;
 436	if (flags & AT_EMPTY_PATH)
 437		lookup_flags |= LOOKUP_EMPTY;
 438
 439	if (!(flags & AT_EACCESS)) {
 440		old_cred = access_override_creds();
 441		if (!old_cred)
 442			return -ENOMEM;
 443	}
 444
 445retry:
 446	res = user_path_at(dfd, filename, lookup_flags, &path);
 447	if (res)
 448		goto out;
 449
 450	inode = d_backing_inode(path.dentry);
 451
 452	if ((mode & MAY_EXEC) && S_ISREG(inode->i_mode)) {
 453		/*
 454		 * MAY_EXEC on regular files is denied if the fs is mounted
 455		 * with the "noexec" flag.
 456		 */
 457		res = -EACCES;
 458		if (path_noexec(&path))
 459			goto out_path_release;
 460	}
 461
 462	res = inode_permission(mnt_user_ns(path.mnt), inode, mode | MAY_ACCESS);
 463	/* SuS v2 requires we report a read only fs too */
 464	if (res || !(mode & S_IWOTH) || special_file(inode->i_mode))
 465		goto out_path_release;
 466	/*
 467	 * This is a rare case where using __mnt_is_readonly()
 468	 * is OK without a mnt_want/drop_write() pair.  Since
 469	 * no actual write to the fs is performed here, we do
 470	 * not need to telegraph to that to anyone.
 471	 *
 472	 * By doing this, we accept that this access is
 473	 * inherently racy and know that the fs may change
 474	 * state before we even see this result.
 475	 */
 476	if (__mnt_is_readonly(path.mnt))
 477		res = -EROFS;
 478
 479out_path_release:
 480	path_put(&path);
 481	if (retry_estale(res, lookup_flags)) {
 482		lookup_flags |= LOOKUP_REVAL;
 483		goto retry;
 484	}
 485out:
 486	if (old_cred)
 487		revert_creds(old_cred);
 488
 489	return res;
 490}
 491
 492SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode)
 493{
 494	return do_faccessat(dfd, filename, mode, 0);
 495}
 496
 497SYSCALL_DEFINE4(faccessat2, int, dfd, const char __user *, filename, int, mode,
 498		int, flags)
 499{
 500	return do_faccessat(dfd, filename, mode, flags);
 501}
 502
 503SYSCALL_DEFINE2(access, const char __user *, filename, int, mode)
 504{
 505	return do_faccessat(AT_FDCWD, filename, mode, 0);
 506}
 507
 508SYSCALL_DEFINE1(chdir, const char __user *, filename)
 509{
 510	struct path path;
 511	int error;
 512	unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
 513retry:
 514	error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
 515	if (error)
 516		goto out;
 517
 518	error = path_permission(&path, MAY_EXEC | MAY_CHDIR);
 519	if (error)
 520		goto dput_and_out;
 521
 522	set_fs_pwd(current->fs, &path);
 523
 524dput_and_out:
 525	path_put(&path);
 526	if (retry_estale(error, lookup_flags)) {
 527		lookup_flags |= LOOKUP_REVAL;
 528		goto retry;
 529	}
 530out:
 531	return error;
 532}
 533
 
 
 
 
 
 534SYSCALL_DEFINE1(fchdir, unsigned int, fd)
 535{
 536	struct fd f = fdget_raw(fd);
 537	int error;
 538
 539	error = -EBADF;
 540	if (!f.file)
 541		goto out;
 542
 543	error = -ENOTDIR;
 544	if (!d_can_lookup(f.file->f_path.dentry))
 545		goto out_putf;
 546
 547	error = file_permission(f.file, MAY_EXEC | MAY_CHDIR);
 548	if (!error)
 549		set_fs_pwd(current->fs, &f.file->f_path);
 550out_putf:
 551	fdput(f);
 552out:
 553	return error;
 554}
 555
 556SYSCALL_DEFINE1(chroot, const char __user *, filename)
 557{
 558	struct path path;
 559	int error;
 560	unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
 561retry:
 562	error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
 563	if (error)
 564		goto out;
 565
 566	error = path_permission(&path, MAY_EXEC | MAY_CHDIR);
 567	if (error)
 568		goto dput_and_out;
 569
 570	error = -EPERM;
 571	if (!ns_capable(current_user_ns(), CAP_SYS_CHROOT))
 572		goto dput_and_out;
 573	error = security_path_chroot(&path);
 574	if (error)
 575		goto dput_and_out;
 576
 577	set_fs_root(current->fs, &path);
 578	error = 0;
 579dput_and_out:
 580	path_put(&path);
 581	if (retry_estale(error, lookup_flags)) {
 582		lookup_flags |= LOOKUP_REVAL;
 583		goto retry;
 584	}
 585out:
 586	return error;
 587}
 588
 589int chmod_common(const struct path *path, umode_t mode)
 
 
 
 
 
 590{
 591	struct inode *inode = path->dentry->d_inode;
 592	struct inode *delegated_inode = NULL;
 593	struct iattr newattrs;
 594	int error;
 595
 596	error = mnt_want_write(path->mnt);
 597	if (error)
 598		return error;
 599retry_deleg:
 600	inode_lock(inode);
 601	error = security_path_chmod(path, mode);
 602	if (error)
 603		goto out_unlock;
 604	newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
 605	newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
 606	error = notify_change(mnt_user_ns(path->mnt), path->dentry,
 607			      &newattrs, &delegated_inode);
 608out_unlock:
 609	inode_unlock(inode);
 610	if (delegated_inode) {
 611		error = break_deleg_wait(&delegated_inode);
 612		if (!error)
 613			goto retry_deleg;
 614	}
 615	mnt_drop_write(path->mnt);
 616	return error;
 617}
 618
 619int vfs_fchmod(struct file *file, umode_t mode)
 620{
 621	audit_file(file);
 622	return chmod_common(&file->f_path, mode);
 623}
 624
 625SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode)
 626{
 627	struct fd f = fdget(fd);
 628	int err = -EBADF;
 629
 630	if (f.file) {
 631		err = vfs_fchmod(f.file, mode);
 
 632		fdput(f);
 633	}
 634	return err;
 635}
 636
 637static int do_fchmodat(int dfd, const char __user *filename, umode_t mode)
 
 
 
 
 
 638{
 639	struct path path;
 640	int error;
 641	unsigned int lookup_flags = LOOKUP_FOLLOW;
 642retry:
 643	error = user_path_at(dfd, filename, lookup_flags, &path);
 644	if (!error) {
 645		error = chmod_common(&path, mode);
 646		path_put(&path);
 647		if (retry_estale(error, lookup_flags)) {
 648			lookup_flags |= LOOKUP_REVAL;
 649			goto retry;
 650		}
 651	}
 652	return error;
 653}
 654
 655SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename,
 656		umode_t, mode)
 657{
 658	return do_fchmodat(dfd, filename, mode);
 659}
 660
 661SYSCALL_DEFINE2(chmod, const char __user *, filename, umode_t, mode)
 662{
 663	return do_fchmodat(AT_FDCWD, filename, mode);
 664}
 665
 666/**
 667 * setattr_vfsuid - check and set ia_fsuid attribute
 668 * @kuid: new inode owner
 669 *
 670 * Check whether @kuid is valid and if so generate and set vfsuid_t in
 671 * ia_vfsuid.
 672 *
 673 * Return: true if @kuid is valid, false if not.
 674 */
 675static inline bool setattr_vfsuid(struct iattr *attr, kuid_t kuid)
 676{
 677	if (!uid_valid(kuid))
 678		return false;
 679	attr->ia_valid |= ATTR_UID;
 680	attr->ia_vfsuid = VFSUIDT_INIT(kuid);
 681	return true;
 682}
 683
 684/**
 685 * setattr_vfsgid - check and set ia_fsgid attribute
 686 * @kgid: new inode owner
 687 *
 688 * Check whether @kgid is valid and if so generate and set vfsgid_t in
 689 * ia_vfsgid.
 690 *
 691 * Return: true if @kgid is valid, false if not.
 692 */
 693static inline bool setattr_vfsgid(struct iattr *attr, kgid_t kgid)
 694{
 695	if (!gid_valid(kgid))
 696		return false;
 697	attr->ia_valid |= ATTR_GID;
 698	attr->ia_vfsgid = VFSGIDT_INIT(kgid);
 699	return true;
 700}
 701
 702int chown_common(const struct path *path, uid_t user, gid_t group)
 703{
 704	struct user_namespace *mnt_userns, *fs_userns;
 705	struct inode *inode = path->dentry->d_inode;
 706	struct inode *delegated_inode = NULL;
 707	int error;
 708	struct iattr newattrs;
 709	kuid_t uid;
 710	kgid_t gid;
 711
 712	uid = make_kuid(current_user_ns(), user);
 713	gid = make_kgid(current_user_ns(), group);
 714
 715	mnt_userns = mnt_user_ns(path->mnt);
 716	fs_userns = i_user_ns(inode);
 717
 718retry_deleg:
 719	newattrs.ia_vfsuid = INVALID_VFSUID;
 720	newattrs.ia_vfsgid = INVALID_VFSGID;
 721	newattrs.ia_valid =  ATTR_CTIME;
 722	if ((user != (uid_t)-1) && !setattr_vfsuid(&newattrs, uid))
 723		return -EINVAL;
 724	if ((group != (gid_t)-1) && !setattr_vfsgid(&newattrs, gid))
 725		return -EINVAL;
 726	inode_lock(inode);
 
 
 
 
 
 
 
 727	if (!S_ISDIR(inode->i_mode))
 728		newattrs.ia_valid |= ATTR_KILL_SUID | ATTR_KILL_PRIV |
 729				     setattr_should_drop_sgid(mnt_userns, inode);
 730	/* Continue to send actual fs values, not the mount values. */
 731	error = security_path_chown(
 732		path,
 733		from_vfsuid(mnt_userns, fs_userns, newattrs.ia_vfsuid),
 734		from_vfsgid(mnt_userns, fs_userns, newattrs.ia_vfsgid));
 735	if (!error)
 736		error = notify_change(mnt_userns, path->dentry, &newattrs,
 737				      &delegated_inode);
 738	inode_unlock(inode);
 739	if (delegated_inode) {
 740		error = break_deleg_wait(&delegated_inode);
 741		if (!error)
 742			goto retry_deleg;
 743	}
 744	return error;
 745}
 746
 747int do_fchownat(int dfd, const char __user *filename, uid_t user, gid_t group,
 748		int flag)
 749{
 750	struct path path;
 751	int error = -EINVAL;
 752	int lookup_flags;
 753
 754	if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
 755		goto out;
 756
 757	lookup_flags = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
 758	if (flag & AT_EMPTY_PATH)
 759		lookup_flags |= LOOKUP_EMPTY;
 760retry:
 761	error = user_path_at(dfd, filename, lookup_flags, &path);
 762	if (error)
 763		goto out;
 764	error = mnt_want_write(path.mnt);
 765	if (error)
 766		goto out_release;
 767	error = chown_common(&path, user, group);
 768	mnt_drop_write(path.mnt);
 769out_release:
 770	path_put(&path);
 771	if (retry_estale(error, lookup_flags)) {
 772		lookup_flags |= LOOKUP_REVAL;
 773		goto retry;
 774	}
 775out:
 776	return error;
 777}
 778
 779SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user,
 780		gid_t, group, int, flag)
 781{
 782	return do_fchownat(dfd, filename, user, group, flag);
 783}
 784
 785SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group)
 786{
 787	return do_fchownat(AT_FDCWD, filename, user, group, 0);
 788}
 789
 790SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group)
 791{
 792	return do_fchownat(AT_FDCWD, filename, user, group,
 793			   AT_SYMLINK_NOFOLLOW);
 794}
 795
 796int vfs_fchown(struct file *file, uid_t user, gid_t group)
 797{
 798	int error;
 799
 800	error = mnt_want_write_file(file);
 801	if (error)
 802		return error;
 803	audit_file(file);
 804	error = chown_common(&file->f_path, user, group);
 805	mnt_drop_write_file(file);
 806	return error;
 807}
 808
 809int ksys_fchown(unsigned int fd, uid_t user, gid_t group)
 810{
 811	struct fd f = fdget(fd);
 812	int error = -EBADF;
 813
 814	if (f.file) {
 815		error = vfs_fchown(f.file, user, group);
 816		fdput(f);
 817	}
 
 
 
 
 
 
 
 
 818	return error;
 819}
 820
 821SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group)
 822{
 823	return ksys_fchown(fd, user, group);
 824}
 825
 826static int do_dentry_open(struct file *f,
 827			  struct inode *inode,
 828			  int (*open)(struct inode *, struct file *))
 829{
 830	static const struct file_operations empty_fops = {};
 831	int error;
 832
 833	path_get(&f->f_path);
 834	f->f_inode = inode;
 835	f->f_mapping = inode->i_mapping;
 
 
 836	f->f_wb_err = filemap_sample_wb_err(f->f_mapping);
 837	f->f_sb_err = file_sample_sb_err(f);
 838
 839	if (unlikely(f->f_flags & O_PATH)) {
 840		f->f_mode = FMODE_PATH | FMODE_OPENED;
 841		f->f_op = &empty_fops;
 842		return 0;
 843	}
 844
 845	if ((f->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ) {
 846		i_readcount_inc(inode);
 847	} else if (f->f_mode & FMODE_WRITE && !special_file(inode->i_mode)) {
 
 
 
 
 848		error = get_write_access(inode);
 849		if (unlikely(error))
 850			goto cleanup_file;
 851		error = __mnt_want_write(f->f_path.mnt);
 852		if (unlikely(error)) {
 853			put_write_access(inode);
 854			goto cleanup_file;
 855		}
 856		f->f_mode |= FMODE_WRITER;
 857	}
 858
 859	/* POSIX.1-2008/SUSv4 Section XSI 2.9.7 */
 860	if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode))
 861		f->f_mode |= FMODE_ATOMIC_POS;
 862
 863	f->f_op = fops_get(inode->i_fop);
 864	if (WARN_ON(!f->f_op)) {
 865		error = -ENODEV;
 866		goto cleanup_all;
 867	}
 868
 869	error = security_file_open(f);
 870	if (error)
 871		goto cleanup_all;
 872
 873	error = break_lease(locks_inode(f), f->f_flags);
 874	if (error)
 875		goto cleanup_all;
 876
 877	/* normally all 3 are set; ->open() can clear them if needed */
 878	f->f_mode |= FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE;
 879	if (!open)
 880		open = f->f_op->open;
 881	if (open) {
 882		error = open(inode, f);
 883		if (error)
 884			goto cleanup_all;
 885	}
 886	f->f_mode |= FMODE_OPENED;
 
 
 887	if ((f->f_mode & FMODE_READ) &&
 888	     likely(f->f_op->read || f->f_op->read_iter))
 889		f->f_mode |= FMODE_CAN_READ;
 890	if ((f->f_mode & FMODE_WRITE) &&
 891	     likely(f->f_op->write || f->f_op->write_iter))
 892		f->f_mode |= FMODE_CAN_WRITE;
 893	if ((f->f_mode & FMODE_LSEEK) && !f->f_op->llseek)
 894		f->f_mode &= ~FMODE_LSEEK;
 895	if (f->f_mapping->a_ops && f->f_mapping->a_ops->direct_IO)
 896		f->f_mode |= FMODE_CAN_ODIRECT;
 897
 
 898	f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
 899	f->f_iocb_flags = iocb_flags(f);
 900
 901	file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);
 902
 903	if ((f->f_flags & O_DIRECT) && !(f->f_mode & FMODE_CAN_ODIRECT))
 904		return -EINVAL;
 
 
 
 905
 906	/*
 907	 * XXX: Huge page cache doesn't support writing yet. Drop all page
 908	 * cache for this file before processing writes.
 909	 */
 910	if (f->f_mode & FMODE_WRITE) {
 911		/*
 912		 * Paired with smp_mb() in collapse_file() to ensure nr_thps
 913		 * is up to date and the update to i_writecount by
 914		 * get_write_access() is visible. Ensures subsequent insertion
 915		 * of THPs into the page cache will fail.
 916		 */
 917		smp_mb();
 918		if (filemap_nr_thps(inode->i_mapping)) {
 919			struct address_space *mapping = inode->i_mapping;
 920
 921			filemap_invalidate_lock(inode->i_mapping);
 922			/*
 923			 * unmap_mapping_range just need to be called once
 924			 * here, because the private pages is not need to be
 925			 * unmapped mapping (e.g. data segment of dynamic
 926			 * shared libraries here).
 927			 */
 928			unmap_mapping_range(mapping, 0, 0, 0);
 929			truncate_inode_pages(mapping, 0);
 930			filemap_invalidate_unlock(inode->i_mapping);
 931		}
 932	}
 933
 934	return 0;
 935
 936cleanup_all:
 937	if (WARN_ON_ONCE(error > 0))
 938		error = -EINVAL;
 939	fops_put(f->f_op);
 940	put_file_access(f);
 
 
 
 941cleanup_file:
 942	path_put(&f->f_path);
 943	f->f_path.mnt = NULL;
 944	f->f_path.dentry = NULL;
 945	f->f_inode = NULL;
 946	return error;
 947}
 948
 949/**
 950 * finish_open - finish opening a file
 951 * @file: file pointer
 952 * @dentry: pointer to dentry
 953 * @open: open callback
 954 * @opened: state of open
 955 *
 956 * This can be used to finish opening a file passed to i_op->atomic_open().
 957 *
 958 * If the open callback is set to NULL, then the standard f_op->open()
 959 * filesystem callback is substituted.
 960 *
 961 * NB: the dentry reference is _not_ consumed.  If, for example, the dentry is
 962 * the return value of d_splice_alias(), then the caller needs to perform dput()
 963 * on it after finish_open().
 964 *
 
 
 
 965 * Returns zero on success or -errno if the open failed.
 966 */
 967int finish_open(struct file *file, struct dentry *dentry,
 968		int (*open)(struct inode *, struct file *))
 969{
 970	BUG_ON(file->f_mode & FMODE_OPENED); /* once it's opened, it's opened */
 971
 972	file->f_path.dentry = dentry;
 973	return do_dentry_open(file, d_backing_inode(dentry), open);
 974}
 975EXPORT_SYMBOL(finish_open);
 976
 977/**
 978 * finish_no_open - finish ->atomic_open() without opening the file
 979 *
 980 * @file: file pointer
 981 * @dentry: dentry or NULL (as returned from ->lookup())
 982 *
 983 * This can be used to set the result of a successful lookup in ->atomic_open().
 984 *
 985 * NB: unlike finish_open() this function does consume the dentry reference and
 986 * the caller need not dput() it.
 987 *
 988 * Returns "0" which must be the return value of ->atomic_open() after having
 989 * called this function.
 990 */
 991int finish_no_open(struct file *file, struct dentry *dentry)
 992{
 993	file->f_path.dentry = dentry;
 994	return 0;
 995}
 996EXPORT_SYMBOL(finish_no_open);
 997
 998char *file_path(struct file *filp, char *buf, int buflen)
 999{
1000	return d_path(&filp->f_path, buf, buflen);
1001}
1002EXPORT_SYMBOL(file_path);
1003
1004/**
1005 * vfs_open - open the file at the given path
1006 * @path: path to open
1007 * @file: newly allocated file with f_flag initialized
1008 * @cred: credentials to use
1009 */
1010int vfs_open(const struct path *path, struct file *file)
1011{
1012	file->f_path = *path;
1013	return do_dentry_open(file, d_backing_inode(path->dentry), NULL);
1014}
1015
1016struct file *dentry_open(const struct path *path, int flags,
1017			 const struct cred *cred)
1018{
1019	int error;
1020	struct file *f;
1021
1022	validate_creds(cred);
1023
1024	/* We must always pass in a valid mount pointer. */
1025	BUG_ON(!path->mnt);
1026
1027	f = alloc_empty_file(flags, cred);
1028	if (!IS_ERR(f)) {
1029		error = vfs_open(path, f);
1030		if (error) {
1031			fput(f);
1032			f = ERR_PTR(error);
1033		}
1034	}
1035	return f;
1036}
1037EXPORT_SYMBOL(dentry_open);
1038
1039/**
1040 * dentry_create - Create and open a file
1041 * @path: path to create
1042 * @flags: O_ flags
1043 * @mode: mode bits for new file
1044 * @cred: credentials to use
1045 *
1046 * Caller must hold the parent directory's lock, and have prepared
1047 * a negative dentry, placed in @path->dentry, for the new file.
1048 *
1049 * Caller sets @path->mnt to the vfsmount of the filesystem where
1050 * the new file is to be created. The parent directory and the
1051 * negative dentry must reside on the same filesystem instance.
1052 *
1053 * On success, returns a "struct file *". Otherwise a ERR_PTR
1054 * is returned.
1055 */
1056struct file *dentry_create(const struct path *path, int flags, umode_t mode,
1057			   const struct cred *cred)
1058{
1059	struct file *f;
1060	int error;
1061
1062	validate_creds(cred);
1063	f = alloc_empty_file(flags, cred);
1064	if (IS_ERR(f))
1065		return f;
1066
1067	error = vfs_create(mnt_user_ns(path->mnt),
1068			   d_inode(path->dentry->d_parent),
1069			   path->dentry, mode, true);
1070	if (!error)
1071		error = vfs_open(path, f);
1072
1073	if (unlikely(error)) {
1074		fput(f);
1075		return ERR_PTR(error);
1076	}
1077	return f;
1078}
1079EXPORT_SYMBOL(dentry_create);
1080
1081struct file *open_with_fake_path(const struct path *path, int flags,
1082				struct inode *inode, const struct cred *cred)
1083{
1084	struct file *f = alloc_empty_file_noaccount(flags, cred);
1085	if (!IS_ERR(f)) {
1086		int error;
1087
1088		f->f_path = *path;
1089		error = do_dentry_open(f, inode, NULL);
1090		if (error) {
1091			fput(f);
1092			f = ERR_PTR(error);
1093		}
1094	}
1095	return f;
1096}
1097EXPORT_SYMBOL(open_with_fake_path);
1098
1099#define WILL_CREATE(flags)	(flags & (O_CREAT | __O_TMPFILE))
1100#define O_PATH_FLAGS		(O_DIRECTORY | O_NOFOLLOW | O_PATH | O_CLOEXEC)
1101
1102inline struct open_how build_open_how(int flags, umode_t mode)
1103{
1104	struct open_how how = {
1105		.flags = flags & VALID_OPEN_FLAGS,
1106		.mode = mode & S_IALLUGO,
1107	};
1108
1109	/* O_PATH beats everything else. */
1110	if (how.flags & O_PATH)
1111		how.flags &= O_PATH_FLAGS;
1112	/* Modes should only be set for create-like flags. */
1113	if (!WILL_CREATE(how.flags))
1114		how.mode = 0;
1115	return how;
1116}
1117
1118inline int build_open_flags(const struct open_how *how, struct open_flags *op)
1119{
1120	u64 flags = how->flags;
1121	u64 strip = FMODE_NONOTIFY | O_CLOEXEC;
1122	int lookup_flags = 0;
1123	int acc_mode = ACC_MODE(flags);
1124
1125	BUILD_BUG_ON_MSG(upper_32_bits(VALID_OPEN_FLAGS),
1126			 "struct open_flags doesn't yet handle flags > 32 bits");
1127
1128	/*
1129	 * Strip flags that either shouldn't be set by userspace like
1130	 * FMODE_NONOTIFY or that aren't relevant in determining struct
1131	 * open_flags like O_CLOEXEC.
1132	 */
1133	flags &= ~strip;
1134
1135	/*
1136	 * Older syscalls implicitly clear all of the invalid flags or argument
1137	 * values before calling build_open_flags(), but openat2(2) checks all
1138	 * of its arguments.
1139	 */
1140	if (flags & ~VALID_OPEN_FLAGS)
1141		return -EINVAL;
1142	if (how->resolve & ~VALID_RESOLVE_FLAGS)
1143		return -EINVAL;
1144
1145	/* Scoping flags are mutually exclusive. */
1146	if ((how->resolve & RESOLVE_BENEATH) && (how->resolve & RESOLVE_IN_ROOT))
1147		return -EINVAL;
1148
1149	/* Deal with the mode. */
1150	if (WILL_CREATE(flags)) {
1151		if (how->mode & ~S_IALLUGO)
1152			return -EINVAL;
1153		op->mode = how->mode | S_IFREG;
1154	} else {
1155		if (how->mode != 0)
1156			return -EINVAL;
1157		op->mode = 0;
1158	}
1159
1160	/*
1161	 * In order to ensure programs get explicit errors when trying to use
1162	 * O_TMPFILE on old kernels, O_TMPFILE is implemented such that it
1163	 * looks like (O_DIRECTORY|O_RDWR & ~O_CREAT) to old kernels. But we
1164	 * have to require userspace to explicitly set it.
1165	 */
1166	if (flags & __O_TMPFILE) {
1167		if ((flags & O_TMPFILE_MASK) != O_TMPFILE)
1168			return -EINVAL;
1169		if (!(acc_mode & MAY_WRITE))
1170			return -EINVAL;
1171	}
1172	if (flags & O_PATH) {
1173		/* O_PATH only permits certain other flags to be set. */
1174		if (flags & ~O_PATH_FLAGS)
1175			return -EINVAL;
1176		acc_mode = 0;
1177	}
1178
1179	/*
1180	 * O_SYNC is implemented as __O_SYNC|O_DSYNC.  As many places only
1181	 * check for O_DSYNC if the need any syncing at all we enforce it's
1182	 * always set instead of having to deal with possibly weird behaviour
1183	 * for malicious applications setting only __O_SYNC.
1184	 */
1185	if (flags & __O_SYNC)
1186		flags |= O_DSYNC;
1187
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1188	op->open_flag = flags;
1189
1190	/* O_TRUNC implies we need access checks for write permissions */
1191	if (flags & O_TRUNC)
1192		acc_mode |= MAY_WRITE;
1193
1194	/* Allow the LSM permission hook to distinguish append
1195	   access from general write access. */
1196	if (flags & O_APPEND)
1197		acc_mode |= MAY_APPEND;
1198
1199	op->acc_mode = acc_mode;
1200
1201	op->intent = flags & O_PATH ? 0 : LOOKUP_OPEN;
1202
1203	if (flags & O_CREAT) {
1204		op->intent |= LOOKUP_CREATE;
1205		if (flags & O_EXCL) {
1206			op->intent |= LOOKUP_EXCL;
1207			flags |= O_NOFOLLOW;
1208		}
1209	}
1210
1211	if (flags & O_DIRECTORY)
1212		lookup_flags |= LOOKUP_DIRECTORY;
1213	if (!(flags & O_NOFOLLOW))
1214		lookup_flags |= LOOKUP_FOLLOW;
1215
1216	if (how->resolve & RESOLVE_NO_XDEV)
1217		lookup_flags |= LOOKUP_NO_XDEV;
1218	if (how->resolve & RESOLVE_NO_MAGICLINKS)
1219		lookup_flags |= LOOKUP_NO_MAGICLINKS;
1220	if (how->resolve & RESOLVE_NO_SYMLINKS)
1221		lookup_flags |= LOOKUP_NO_SYMLINKS;
1222	if (how->resolve & RESOLVE_BENEATH)
1223		lookup_flags |= LOOKUP_BENEATH;
1224	if (how->resolve & RESOLVE_IN_ROOT)
1225		lookup_flags |= LOOKUP_IN_ROOT;
1226	if (how->resolve & RESOLVE_CACHED) {
1227		/* Don't bother even trying for create/truncate/tmpfile open */
1228		if (flags & (O_TRUNC | O_CREAT | O_TMPFILE))
1229			return -EAGAIN;
1230		lookup_flags |= LOOKUP_CACHED;
1231	}
1232
1233	op->lookup_flags = lookup_flags;
1234	return 0;
1235}
1236
1237/**
1238 * file_open_name - open file and return file pointer
1239 *
1240 * @name:	struct filename containing path to open
1241 * @flags:	open flags as per the open(2) second argument
1242 * @mode:	mode for the new file if O_CREAT is set, else ignored
1243 *
1244 * This is the helper to open a file from kernelspace if you really
1245 * have to.  But in generally you should not do this, so please move
1246 * along, nothing to see here..
1247 */
1248struct file *file_open_name(struct filename *name, int flags, umode_t mode)
1249{
1250	struct open_flags op;
1251	struct open_how how = build_open_how(flags, mode);
1252	int err = build_open_flags(&how, &op);
1253	if (err)
1254		return ERR_PTR(err);
1255	return do_filp_open(AT_FDCWD, name, &op);
1256}
1257
1258/**
1259 * filp_open - open file and return file pointer
1260 *
1261 * @filename:	path to open
1262 * @flags:	open flags as per the open(2) second argument
1263 * @mode:	mode for the new file if O_CREAT is set, else ignored
1264 *
1265 * This is the helper to open a file from kernelspace if you really
1266 * have to.  But in generally you should not do this, so please move
1267 * along, nothing to see here..
1268 */
1269struct file *filp_open(const char *filename, int flags, umode_t mode)
1270{
1271	struct filename *name = getname_kernel(filename);
1272	struct file *file = ERR_CAST(name);
1273	
1274	if (!IS_ERR(name)) {
1275		file = file_open_name(name, flags, mode);
1276		putname(name);
1277	}
1278	return file;
1279}
1280EXPORT_SYMBOL(filp_open);
1281
1282struct file *file_open_root(const struct path *root,
1283			    const char *filename, int flags, umode_t mode)
1284{
1285	struct open_flags op;
1286	struct open_how how = build_open_how(flags, mode);
1287	int err = build_open_flags(&how, &op);
1288	if (err)
1289		return ERR_PTR(err);
1290	return do_file_open_root(root, filename, &op);
1291}
1292EXPORT_SYMBOL(file_open_root);
1293
1294static long do_sys_openat2(int dfd, const char __user *filename,
1295			   struct open_how *how)
1296{
1297	struct open_flags op;
1298	int fd = build_open_flags(how, &op);
1299	struct filename *tmp;
1300
1301	if (fd)
1302		return fd;
1303
1304	tmp = getname(filename);
1305	if (IS_ERR(tmp))
1306		return PTR_ERR(tmp);
1307
1308	fd = get_unused_fd_flags(how->flags);
1309	if (fd >= 0) {
1310		struct file *f = do_filp_open(dfd, tmp, &op);
1311		if (IS_ERR(f)) {
1312			put_unused_fd(fd);
1313			fd = PTR_ERR(f);
1314		} else {
1315			fsnotify_open(f);
1316			fd_install(fd, f);
1317		}
1318	}
1319	putname(tmp);
1320	return fd;
1321}
1322
1323long do_sys_open(int dfd, const char __user *filename, int flags, umode_t mode)
1324{
1325	struct open_how how = build_open_how(flags, mode);
1326	return do_sys_openat2(dfd, filename, &how);
1327}
1328
1329
1330SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)
1331{
1332	if (force_o_largefile())
1333		flags |= O_LARGEFILE;
 
1334	return do_sys_open(AT_FDCWD, filename, flags, mode);
1335}
1336
1337SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags,
1338		umode_t, mode)
1339{
1340	if (force_o_largefile())
1341		flags |= O_LARGEFILE;
1342	return do_sys_open(dfd, filename, flags, mode);
1343}
1344
1345SYSCALL_DEFINE4(openat2, int, dfd, const char __user *, filename,
1346		struct open_how __user *, how, size_t, usize)
1347{
1348	int err;
1349	struct open_how tmp;
1350
1351	BUILD_BUG_ON(sizeof(struct open_how) < OPEN_HOW_SIZE_VER0);
1352	BUILD_BUG_ON(sizeof(struct open_how) != OPEN_HOW_SIZE_LATEST);
1353
1354	if (unlikely(usize < OPEN_HOW_SIZE_VER0))
1355		return -EINVAL;
1356
1357	err = copy_struct_from_user(&tmp, sizeof(tmp), how, usize);
1358	if (err)
1359		return err;
1360
1361	audit_openat2_how(&tmp);
1362
1363	/* O_LARGEFILE is only allowed for non-O_PATH. */
1364	if (!(tmp.flags & O_PATH) && force_o_largefile())
1365		tmp.flags |= O_LARGEFILE;
1366
1367	return do_sys_openat2(dfd, filename, &tmp);
1368}
1369
1370#ifdef CONFIG_COMPAT
1371/*
1372 * Exactly like sys_open(), except that it doesn't set the
1373 * O_LARGEFILE flag.
1374 */
1375COMPAT_SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)
1376{
1377	return do_sys_open(AT_FDCWD, filename, flags, mode);
1378}
1379
1380/*
1381 * Exactly like sys_openat(), except that it doesn't set the
1382 * O_LARGEFILE flag.
1383 */
1384COMPAT_SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags, umode_t, mode)
1385{
1386	return do_sys_open(dfd, filename, flags, mode);
1387}
1388#endif
1389
1390#ifndef __alpha__
1391
1392/*
1393 * For backward compatibility?  Maybe this should be moved
1394 * into arch/i386 instead?
1395 */
1396SYSCALL_DEFINE2(creat, const char __user *, pathname, umode_t, mode)
1397{
1398	int flags = O_CREAT | O_WRONLY | O_TRUNC;
1399
1400	if (force_o_largefile())
1401		flags |= O_LARGEFILE;
1402	return do_sys_open(AT_FDCWD, pathname, flags, mode);
1403}
 
1404#endif
1405
1406/*
1407 * "id" is the POSIX thread ID. We use the
1408 * files pointer for this..
1409 */
1410int filp_close(struct file *filp, fl_owner_t id)
1411{
1412	int retval = 0;
1413
1414	if (!file_count(filp)) {
1415		printk(KERN_ERR "VFS: Close: file count is 0\n");
1416		return 0;
1417	}
1418
1419	if (filp->f_op->flush)
1420		retval = filp->f_op->flush(filp, id);
1421
1422	if (likely(!(filp->f_mode & FMODE_PATH))) {
1423		dnotify_flush(filp, id);
1424		locks_remove_posix(filp, id);
1425	}
1426	fput(filp);
1427	return retval;
1428}
1429
1430EXPORT_SYMBOL(filp_close);
1431
1432/*
1433 * Careful here! We test whether the file pointer is NULL before
1434 * releasing the fd. This ensures that one clone task can't release
1435 * an fd while another clone is opening it.
1436 */
1437SYSCALL_DEFINE1(close, unsigned int, fd)
1438{
1439	int retval = close_fd(fd);
1440
1441	/* can't restart close syscall because file table entry was cleared */
1442	if (unlikely(retval == -ERESTARTSYS ||
1443		     retval == -ERESTARTNOINTR ||
1444		     retval == -ERESTARTNOHAND ||
1445		     retval == -ERESTART_RESTARTBLOCK))
1446		retval = -EINTR;
1447
1448	return retval;
1449}
1450
1451/**
1452 * close_range() - Close all file descriptors in a given range.
1453 *
1454 * @fd:     starting file descriptor to close
1455 * @max_fd: last file descriptor to close
1456 * @flags:  reserved for future extensions
1457 *
1458 * This closes a range of file descriptors. All file descriptors
1459 * from @fd up to and including @max_fd are closed.
1460 * Currently, errors to close a given file descriptor are ignored.
1461 */
1462SYSCALL_DEFINE3(close_range, unsigned int, fd, unsigned int, max_fd,
1463		unsigned int, flags)
1464{
1465	return __close_range(fd, max_fd, flags);
1466}
1467
1468/*
1469 * This routine simulates a hangup on the tty, to arrange that users
1470 * are given clean terminals at login time.
1471 */
1472SYSCALL_DEFINE0(vhangup)
1473{
1474	if (capable(CAP_SYS_TTY_CONFIG)) {
1475		tty_vhangup_self();
1476		return 0;
1477	}
1478	return -EPERM;
1479}
1480
1481/*
1482 * Called when an inode is about to be open.
1483 * We use this to disallow opening large files on 32bit systems if
1484 * the caller didn't specify O_LARGEFILE.  On 64bit systems we force
1485 * on this flag in sys_open.
1486 */
1487int generic_file_open(struct inode * inode, struct file * filp)
1488{
1489	if (!(filp->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS)
1490		return -EOVERFLOW;
1491	return 0;
1492}
1493
1494EXPORT_SYMBOL(generic_file_open);
1495
1496/*
1497 * This is used by subsystems that don't want seekable
1498 * file descriptors. The function is not supposed to ever fail, the only
1499 * reason it returns an 'int' and not 'void' is so that it can be plugged
1500 * directly into file_operations structure.
1501 */
1502int nonseekable_open(struct inode *inode, struct file *filp)
1503{
1504	filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);
1505	return 0;
1506}
1507
1508EXPORT_SYMBOL(nonseekable_open);
1509
1510/*
1511 * stream_open is used by subsystems that want stream-like file descriptors.
1512 * Such file descriptors are not seekable and don't have notion of position
1513 * (file.f_pos is always 0 and ppos passed to .read()/.write() is always NULL).
1514 * Contrary to file descriptors of other regular files, .read() and .write()
1515 * can run simultaneously.
1516 *
1517 * stream_open never fails and is marked to return int so that it could be
1518 * directly used as file_operations.open .
1519 */
1520int stream_open(struct inode *inode, struct file *filp)
1521{
1522	filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE | FMODE_ATOMIC_POS);
1523	filp->f_mode |= FMODE_STREAM;
1524	return 0;
1525}
1526
1527EXPORT_SYMBOL(stream_open);
v5.4
   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 */
 348long do_faccessat(int dfd, const char __user *filename, int mode)
 349{
 350	const struct cred *old_cred;
 351	struct cred *override_cred;
 352	struct path path;
 353	struct inode *inode;
 354	int res;
 355	unsigned int lookup_flags = LOOKUP_FOLLOW;
 356
 357	if (mode & ~S_IRWXO)	/* where's F_OK, X_OK, W_OK, R_OK? */
 358		return -EINVAL;
 359
 360	override_cred = prepare_creds();
 361	if (!override_cred)
 362		return -ENOMEM;
 363
 364	override_cred->fsuid = override_cred->uid;
 365	override_cred->fsgid = override_cred->gid;
 366
 367	if (!issecure(SECURE_NO_SETUID_FIXUP)) {
 368		/* Clear the capabilities if we switch to a non-root user */
 369		kuid_t root_uid = make_kuid(override_cred->user_ns, 0);
 370		if (!uid_eq(override_cred->uid, root_uid))
 371			cap_clear(override_cred->cap_effective);
 372		else
 373			override_cred->cap_effective =
 374				override_cred->cap_permitted;
 375	}
 376
 377	/*
 378	 * The new set of credentials can *only* be used in
 379	 * task-synchronous circumstances, and does not need
 380	 * RCU freeing, unless somebody then takes a separate
 381	 * reference to it.
 382	 *
 383	 * NOTE! This is _only_ true because this credential
 384	 * is used purely for override_creds() that installs
 385	 * it as the subjective cred. Other threads will be
 386	 * accessing ->real_cred, not the subjective cred.
 387	 *
 388	 * If somebody _does_ make a copy of this (using the
 389	 * 'get_current_cred()' function), that will clear the
 390	 * non_rcu field, because now that other user may be
 391	 * expecting RCU freeing. But normal thread-synchronous
 392	 * cred accesses will keep things non-RCY.
 393	 */
 394	override_cred->non_rcu = 1;
 395
 396	old_cred = override_creds(override_cred);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 397retry:
 398	res = user_path_at(dfd, filename, lookup_flags, &path);
 399	if (res)
 400		goto out;
 401
 402	inode = d_backing_inode(path.dentry);
 403
 404	if ((mode & MAY_EXEC) && S_ISREG(inode->i_mode)) {
 405		/*
 406		 * MAY_EXEC on regular files is denied if the fs is mounted
 407		 * with the "noexec" flag.
 408		 */
 409		res = -EACCES;
 410		if (path_noexec(&path))
 411			goto out_path_release;
 412	}
 413
 414	res = inode_permission(inode, mode | MAY_ACCESS);
 415	/* SuS v2 requires we report a read only fs too */
 416	if (res || !(mode & S_IWOTH) || special_file(inode->i_mode))
 417		goto out_path_release;
 418	/*
 419	 * This is a rare case where using __mnt_is_readonly()
 420	 * is OK without a mnt_want/drop_write() pair.  Since
 421	 * no actual write to the fs is performed here, we do
 422	 * not need to telegraph to that to anyone.
 423	 *
 424	 * By doing this, we accept that this access is
 425	 * inherently racy and know that the fs may change
 426	 * state before we even see this result.
 427	 */
 428	if (__mnt_is_readonly(path.mnt))
 429		res = -EROFS;
 430
 431out_path_release:
 432	path_put(&path);
 433	if (retry_estale(res, lookup_flags)) {
 434		lookup_flags |= LOOKUP_REVAL;
 435		goto retry;
 436	}
 437out:
 438	revert_creds(old_cred);
 439	put_cred(override_cred);
 
 440	return res;
 441}
 442
 443SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode)
 444{
 445	return do_faccessat(dfd, filename, mode);
 
 
 
 
 
 
 446}
 447
 448SYSCALL_DEFINE2(access, const char __user *, filename, int, mode)
 449{
 450	return do_faccessat(AT_FDCWD, filename, mode);
 451}
 452
 453int ksys_chdir(const char __user *filename)
 454{
 455	struct path path;
 456	int error;
 457	unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
 458retry:
 459	error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
 460	if (error)
 461		goto out;
 462
 463	error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
 464	if (error)
 465		goto dput_and_out;
 466
 467	set_fs_pwd(current->fs, &path);
 468
 469dput_and_out:
 470	path_put(&path);
 471	if (retry_estale(error, lookup_flags)) {
 472		lookup_flags |= LOOKUP_REVAL;
 473		goto retry;
 474	}
 475out:
 476	return error;
 477}
 478
 479SYSCALL_DEFINE1(chdir, const char __user *, filename)
 480{
 481	return ksys_chdir(filename);
 482}
 483
 484SYSCALL_DEFINE1(fchdir, unsigned int, fd)
 485{
 486	struct fd f = fdget_raw(fd);
 487	int error;
 488
 489	error = -EBADF;
 490	if (!f.file)
 491		goto out;
 492
 493	error = -ENOTDIR;
 494	if (!d_can_lookup(f.file->f_path.dentry))
 495		goto out_putf;
 496
 497	error = inode_permission(file_inode(f.file), MAY_EXEC | MAY_CHDIR);
 498	if (!error)
 499		set_fs_pwd(current->fs, &f.file->f_path);
 500out_putf:
 501	fdput(f);
 502out:
 503	return error;
 504}
 505
 506int ksys_chroot(const char __user *filename)
 507{
 508	struct path path;
 509	int error;
 510	unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
 511retry:
 512	error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
 513	if (error)
 514		goto out;
 515
 516	error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
 517	if (error)
 518		goto dput_and_out;
 519
 520	error = -EPERM;
 521	if (!ns_capable(current_user_ns(), CAP_SYS_CHROOT))
 522		goto dput_and_out;
 523	error = security_path_chroot(&path);
 524	if (error)
 525		goto dput_and_out;
 526
 527	set_fs_root(current->fs, &path);
 528	error = 0;
 529dput_and_out:
 530	path_put(&path);
 531	if (retry_estale(error, lookup_flags)) {
 532		lookup_flags |= LOOKUP_REVAL;
 533		goto retry;
 534	}
 535out:
 536	return error;
 537}
 538
 539SYSCALL_DEFINE1(chroot, const char __user *, filename)
 540{
 541	return ksys_chroot(filename);
 542}
 543
 544static int chmod_common(const struct path *path, umode_t mode)
 545{
 546	struct inode *inode = path->dentry->d_inode;
 547	struct inode *delegated_inode = NULL;
 548	struct iattr newattrs;
 549	int error;
 550
 551	error = mnt_want_write(path->mnt);
 552	if (error)
 553		return error;
 554retry_deleg:
 555	inode_lock(inode);
 556	error = security_path_chmod(path, mode);
 557	if (error)
 558		goto out_unlock;
 559	newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
 560	newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
 561	error = notify_change(path->dentry, &newattrs, &delegated_inode);
 
 562out_unlock:
 563	inode_unlock(inode);
 564	if (delegated_inode) {
 565		error = break_deleg_wait(&delegated_inode);
 566		if (!error)
 567			goto retry_deleg;
 568	}
 569	mnt_drop_write(path->mnt);
 570	return error;
 571}
 572
 573int ksys_fchmod(unsigned int fd, umode_t mode)
 
 
 
 
 
 
 574{
 575	struct fd f = fdget(fd);
 576	int err = -EBADF;
 577
 578	if (f.file) {
 579		audit_file(f.file);
 580		err = chmod_common(&f.file->f_path, mode);
 581		fdput(f);
 582	}
 583	return err;
 584}
 585
 586SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode)
 587{
 588	return ksys_fchmod(fd, mode);
 589}
 590
 591int do_fchmodat(int dfd, const char __user *filename, umode_t mode)
 592{
 593	struct path path;
 594	int error;
 595	unsigned int lookup_flags = LOOKUP_FOLLOW;
 596retry:
 597	error = user_path_at(dfd, filename, lookup_flags, &path);
 598	if (!error) {
 599		error = chmod_common(&path, mode);
 600		path_put(&path);
 601		if (retry_estale(error, lookup_flags)) {
 602			lookup_flags |= LOOKUP_REVAL;
 603			goto retry;
 604		}
 605	}
 606	return error;
 607}
 608
 609SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename,
 610		umode_t, mode)
 611{
 612	return do_fchmodat(dfd, filename, mode);
 613}
 614
 615SYSCALL_DEFINE2(chmod, const char __user *, filename, umode_t, mode)
 616{
 617	return do_fchmodat(AT_FDCWD, filename, mode);
 618}
 619
 620static int chown_common(const struct path *path, uid_t user, gid_t group)
 
 
 
 
 
 
 
 
 
 621{
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 622	struct inode *inode = path->dentry->d_inode;
 623	struct inode *delegated_inode = NULL;
 624	int error;
 625	struct iattr newattrs;
 626	kuid_t uid;
 627	kgid_t gid;
 628
 629	uid = make_kuid(current_user_ns(), user);
 630	gid = make_kgid(current_user_ns(), group);
 631
 
 
 
 632retry_deleg:
 
 
 633	newattrs.ia_valid =  ATTR_CTIME;
 634	if (user != (uid_t) -1) {
 635		if (!uid_valid(uid))
 636			return -EINVAL;
 637		newattrs.ia_valid |= ATTR_UID;
 638		newattrs.ia_uid = uid;
 639	}
 640	if (group != (gid_t) -1) {
 641		if (!gid_valid(gid))
 642			return -EINVAL;
 643		newattrs.ia_valid |= ATTR_GID;
 644		newattrs.ia_gid = gid;
 645	}
 646	if (!S_ISDIR(inode->i_mode))
 647		newattrs.ia_valid |=
 648			ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_KILL_PRIV;
 649	inode_lock(inode);
 650	error = security_path_chown(path, uid, gid);
 
 
 
 651	if (!error)
 652		error = notify_change(path->dentry, &newattrs, &delegated_inode);
 
 653	inode_unlock(inode);
 654	if (delegated_inode) {
 655		error = break_deleg_wait(&delegated_inode);
 656		if (!error)
 657			goto retry_deleg;
 658	}
 659	return error;
 660}
 661
 662int do_fchownat(int dfd, const char __user *filename, uid_t user, gid_t group,
 663		int flag)
 664{
 665	struct path path;
 666	int error = -EINVAL;
 667	int lookup_flags;
 668
 669	if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
 670		goto out;
 671
 672	lookup_flags = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
 673	if (flag & AT_EMPTY_PATH)
 674		lookup_flags |= LOOKUP_EMPTY;
 675retry:
 676	error = user_path_at(dfd, filename, lookup_flags, &path);
 677	if (error)
 678		goto out;
 679	error = mnt_want_write(path.mnt);
 680	if (error)
 681		goto out_release;
 682	error = chown_common(&path, user, group);
 683	mnt_drop_write(path.mnt);
 684out_release:
 685	path_put(&path);
 686	if (retry_estale(error, lookup_flags)) {
 687		lookup_flags |= LOOKUP_REVAL;
 688		goto retry;
 689	}
 690out:
 691	return error;
 692}
 693
 694SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user,
 695		gid_t, group, int, flag)
 696{
 697	return do_fchownat(dfd, filename, user, group, flag);
 698}
 699
 700SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group)
 701{
 702	return do_fchownat(AT_FDCWD, filename, user, group, 0);
 703}
 704
 705SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group)
 706{
 707	return do_fchownat(AT_FDCWD, filename, user, group,
 708			   AT_SYMLINK_NOFOLLOW);
 709}
 710
 
 
 
 
 
 
 
 
 
 
 
 
 
 711int ksys_fchown(unsigned int fd, uid_t user, gid_t group)
 712{
 713	struct fd f = fdget(fd);
 714	int error = -EBADF;
 715
 716	if (!f.file)
 717		goto out;
 718
 719	error = mnt_want_write_file(f.file);
 720	if (error)
 721		goto out_fput;
 722	audit_file(f.file);
 723	error = chown_common(&f.file->f_path, user, group);
 724	mnt_drop_write_file(f.file);
 725out_fput:
 726	fdput(f);
 727out:
 728	return error;
 729}
 730
 731SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group)
 732{
 733	return ksys_fchown(fd, user, group);
 734}
 735
 736static int do_dentry_open(struct file *f,
 737			  struct inode *inode,
 738			  int (*open)(struct inode *, struct file *))
 739{
 740	static const struct file_operations empty_fops = {};
 741	int error;
 742
 743	path_get(&f->f_path);
 744	f->f_inode = inode;
 745	f->f_mapping = inode->i_mapping;
 746
 747	/* Ensure that we skip any errors that predate opening of the file */
 748	f->f_wb_err = filemap_sample_wb_err(f->f_mapping);
 
 749
 750	if (unlikely(f->f_flags & O_PATH)) {
 751		f->f_mode = FMODE_PATH | FMODE_OPENED;
 752		f->f_op = &empty_fops;
 753		return 0;
 754	}
 755
 756	/* Any file opened for execve()/uselib() has to be a regular file. */
 757	if (unlikely(f->f_flags & FMODE_EXEC && !S_ISREG(inode->i_mode))) {
 758		error = -EACCES;
 759		goto cleanup_file;
 760	}
 761
 762	if (f->f_mode & FMODE_WRITE && !special_file(inode->i_mode)) {
 763		error = get_write_access(inode);
 764		if (unlikely(error))
 765			goto cleanup_file;
 766		error = __mnt_want_write(f->f_path.mnt);
 767		if (unlikely(error)) {
 768			put_write_access(inode);
 769			goto cleanup_file;
 770		}
 771		f->f_mode |= FMODE_WRITER;
 772	}
 773
 774	/* POSIX.1-2008/SUSv4 Section XSI 2.9.7 */
 775	if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode))
 776		f->f_mode |= FMODE_ATOMIC_POS;
 777
 778	f->f_op = fops_get(inode->i_fop);
 779	if (WARN_ON(!f->f_op)) {
 780		error = -ENODEV;
 781		goto cleanup_all;
 782	}
 783
 784	error = security_file_open(f);
 785	if (error)
 786		goto cleanup_all;
 787
 788	error = break_lease(locks_inode(f), f->f_flags);
 789	if (error)
 790		goto cleanup_all;
 791
 792	/* normally all 3 are set; ->open() can clear them if needed */
 793	f->f_mode |= FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE;
 794	if (!open)
 795		open = f->f_op->open;
 796	if (open) {
 797		error = open(inode, f);
 798		if (error)
 799			goto cleanup_all;
 800	}
 801	f->f_mode |= FMODE_OPENED;
 802	if ((f->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
 803		i_readcount_inc(inode);
 804	if ((f->f_mode & FMODE_READ) &&
 805	     likely(f->f_op->read || f->f_op->read_iter))
 806		f->f_mode |= FMODE_CAN_READ;
 807	if ((f->f_mode & FMODE_WRITE) &&
 808	     likely(f->f_op->write || f->f_op->write_iter))
 809		f->f_mode |= FMODE_CAN_WRITE;
 
 
 
 
 810
 811	f->f_write_hint = WRITE_LIFE_NOT_SET;
 812	f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
 
 813
 814	file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);
 815
 816	/* NB: we're sure to have correct a_ops only after f_op->open */
 817	if (f->f_flags & O_DIRECT) {
 818		if (!f->f_mapping->a_ops || !f->f_mapping->a_ops->direct_IO)
 819			return -EINVAL;
 820	}
 821
 822	/*
 823	 * XXX: Huge page cache doesn't support writing yet. Drop all page
 824	 * cache for this file before processing writes.
 825	 */
 826	if ((f->f_mode & FMODE_WRITE) && filemap_nr_thps(inode->i_mapping))
 827		truncate_pagecache(inode, 0);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 828
 829	return 0;
 830
 831cleanup_all:
 832	if (WARN_ON_ONCE(error > 0))
 833		error = -EINVAL;
 834	fops_put(f->f_op);
 835	if (f->f_mode & FMODE_WRITER) {
 836		put_write_access(inode);
 837		__mnt_drop_write(f->f_path.mnt);
 838	}
 839cleanup_file:
 840	path_put(&f->f_path);
 841	f->f_path.mnt = NULL;
 842	f->f_path.dentry = NULL;
 843	f->f_inode = NULL;
 844	return error;
 845}
 846
 847/**
 848 * finish_open - finish opening a file
 849 * @file: file pointer
 850 * @dentry: pointer to dentry
 851 * @open: open callback
 852 * @opened: state of open
 853 *
 854 * This can be used to finish opening a file passed to i_op->atomic_open().
 855 *
 856 * If the open callback is set to NULL, then the standard f_op->open()
 857 * filesystem callback is substituted.
 858 *
 859 * NB: the dentry reference is _not_ consumed.  If, for example, the dentry is
 860 * the return value of d_splice_alias(), then the caller needs to perform dput()
 861 * on it after finish_open().
 862 *
 863 * On successful return @file is a fully instantiated open file.  After this, if
 864 * an error occurs in ->atomic_open(), it needs to clean up with fput().
 865 *
 866 * Returns zero on success or -errno if the open failed.
 867 */
 868int finish_open(struct file *file, struct dentry *dentry,
 869		int (*open)(struct inode *, struct file *))
 870{
 871	BUG_ON(file->f_mode & FMODE_OPENED); /* once it's opened, it's opened */
 872
 873	file->f_path.dentry = dentry;
 874	return do_dentry_open(file, d_backing_inode(dentry), open);
 875}
 876EXPORT_SYMBOL(finish_open);
 877
 878/**
 879 * finish_no_open - finish ->atomic_open() without opening the file
 880 *
 881 * @file: file pointer
 882 * @dentry: dentry or NULL (as returned from ->lookup())
 883 *
 884 * This can be used to set the result of a successful lookup in ->atomic_open().
 885 *
 886 * NB: unlike finish_open() this function does consume the dentry reference and
 887 * the caller need not dput() it.
 888 *
 889 * Returns "0" which must be the return value of ->atomic_open() after having
 890 * called this function.
 891 */
 892int finish_no_open(struct file *file, struct dentry *dentry)
 893{
 894	file->f_path.dentry = dentry;
 895	return 0;
 896}
 897EXPORT_SYMBOL(finish_no_open);
 898
 899char *file_path(struct file *filp, char *buf, int buflen)
 900{
 901	return d_path(&filp->f_path, buf, buflen);
 902}
 903EXPORT_SYMBOL(file_path);
 904
 905/**
 906 * vfs_open - open the file at the given path
 907 * @path: path to open
 908 * @file: newly allocated file with f_flag initialized
 909 * @cred: credentials to use
 910 */
 911int vfs_open(const struct path *path, struct file *file)
 912{
 913	file->f_path = *path;
 914	return do_dentry_open(file, d_backing_inode(path->dentry), NULL);
 915}
 916
 917struct file *dentry_open(const struct path *path, int flags,
 918			 const struct cred *cred)
 919{
 920	int error;
 921	struct file *f;
 922
 923	validate_creds(cred);
 924
 925	/* We must always pass in a valid mount pointer. */
 926	BUG_ON(!path->mnt);
 927
 928	f = alloc_empty_file(flags, cred);
 929	if (!IS_ERR(f)) {
 930		error = vfs_open(path, f);
 931		if (error) {
 932			fput(f);
 933			f = ERR_PTR(error);
 934		}
 935	}
 936	return f;
 937}
 938EXPORT_SYMBOL(dentry_open);
 939
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 940struct file *open_with_fake_path(const struct path *path, int flags,
 941				struct inode *inode, const struct cred *cred)
 942{
 943	struct file *f = alloc_empty_file_noaccount(flags, cred);
 944	if (!IS_ERR(f)) {
 945		int error;
 946
 947		f->f_path = *path;
 948		error = do_dentry_open(f, inode, NULL);
 949		if (error) {
 950			fput(f);
 951			f = ERR_PTR(error);
 952		}
 953	}
 954	return f;
 955}
 956EXPORT_SYMBOL(open_with_fake_path);
 957
 958static inline int build_open_flags(int flags, umode_t mode, struct open_flags *op)
 
 
 
 959{
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 960	int lookup_flags = 0;
 961	int acc_mode = ACC_MODE(flags);
 962
 
 
 
 
 
 
 
 
 
 
 963	/*
 964	 * Clear out all open flags we don't know about so that we don't report
 965	 * them in fcntl(F_GETFD) or similar interfaces.
 
 966	 */
 967	flags &= VALID_OPEN_FLAGS;
 
 
 
 968
 969	if (flags & (O_CREAT | __O_TMPFILE))
 970		op->mode = (mode & S_IALLUGO) | S_IFREG;
 971	else
 
 
 
 
 
 
 
 
 
 972		op->mode = 0;
 
 973
 974	/* Must never be set by userspace */
 975	flags &= ~FMODE_NONOTIFY & ~O_CLOEXEC;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 976
 977	/*
 978	 * O_SYNC is implemented as __O_SYNC|O_DSYNC.  As many places only
 979	 * check for O_DSYNC if the need any syncing at all we enforce it's
 980	 * always set instead of having to deal with possibly weird behaviour
 981	 * for malicious applications setting only __O_SYNC.
 982	 */
 983	if (flags & __O_SYNC)
 984		flags |= O_DSYNC;
 985
 986	if (flags & __O_TMPFILE) {
 987		if ((flags & O_TMPFILE_MASK) != O_TMPFILE)
 988			return -EINVAL;
 989		if (!(acc_mode & MAY_WRITE))
 990			return -EINVAL;
 991	} else if (flags & O_PATH) {
 992		/*
 993		 * If we have O_PATH in the open flag. Then we
 994		 * cannot have anything other than the below set of flags
 995		 */
 996		flags &= O_DIRECTORY | O_NOFOLLOW | O_PATH;
 997		acc_mode = 0;
 998	}
 999
1000	op->open_flag = flags;
1001
1002	/* O_TRUNC implies we need access checks for write permissions */
1003	if (flags & O_TRUNC)
1004		acc_mode |= MAY_WRITE;
1005
1006	/* Allow the LSM permission hook to distinguish append
1007	   access from general write access. */
1008	if (flags & O_APPEND)
1009		acc_mode |= MAY_APPEND;
1010
1011	op->acc_mode = acc_mode;
1012
1013	op->intent = flags & O_PATH ? 0 : LOOKUP_OPEN;
1014
1015	if (flags & O_CREAT) {
1016		op->intent |= LOOKUP_CREATE;
1017		if (flags & O_EXCL)
1018			op->intent |= LOOKUP_EXCL;
 
 
1019	}
1020
1021	if (flags & O_DIRECTORY)
1022		lookup_flags |= LOOKUP_DIRECTORY;
1023	if (!(flags & O_NOFOLLOW))
1024		lookup_flags |= LOOKUP_FOLLOW;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1025	op->lookup_flags = lookup_flags;
1026	return 0;
1027}
1028
1029/**
1030 * file_open_name - open file and return file pointer
1031 *
1032 * @name:	struct filename containing path to open
1033 * @flags:	open flags as per the open(2) second argument
1034 * @mode:	mode for the new file if O_CREAT is set, else ignored
1035 *
1036 * This is the helper to open a file from kernelspace if you really
1037 * have to.  But in generally you should not do this, so please move
1038 * along, nothing to see here..
1039 */
1040struct file *file_open_name(struct filename *name, int flags, umode_t mode)
1041{
1042	struct open_flags op;
1043	int err = build_open_flags(flags, mode, &op);
1044	return err ? ERR_PTR(err) : do_filp_open(AT_FDCWD, name, &op);
 
 
 
1045}
1046
1047/**
1048 * filp_open - open file and return file pointer
1049 *
1050 * @filename:	path to open
1051 * @flags:	open flags as per the open(2) second argument
1052 * @mode:	mode for the new file if O_CREAT is set, else ignored
1053 *
1054 * This is the helper to open a file from kernelspace if you really
1055 * have to.  But in generally you should not do this, so please move
1056 * along, nothing to see here..
1057 */
1058struct file *filp_open(const char *filename, int flags, umode_t mode)
1059{
1060	struct filename *name = getname_kernel(filename);
1061	struct file *file = ERR_CAST(name);
1062	
1063	if (!IS_ERR(name)) {
1064		file = file_open_name(name, flags, mode);
1065		putname(name);
1066	}
1067	return file;
1068}
1069EXPORT_SYMBOL(filp_open);
1070
1071struct file *file_open_root(struct dentry *dentry, struct vfsmount *mnt,
1072			    const char *filename, int flags, umode_t mode)
1073{
1074	struct open_flags op;
1075	int err = build_open_flags(flags, mode, &op);
 
1076	if (err)
1077		return ERR_PTR(err);
1078	return do_file_open_root(dentry, mnt, filename, &op);
1079}
1080EXPORT_SYMBOL(file_open_root);
1081
1082long do_sys_open(int dfd, const char __user *filename, int flags, umode_t mode)
 
1083{
1084	struct open_flags op;
1085	int fd = build_open_flags(flags, mode, &op);
1086	struct filename *tmp;
1087
1088	if (fd)
1089		return fd;
1090
1091	tmp = getname(filename);
1092	if (IS_ERR(tmp))
1093		return PTR_ERR(tmp);
1094
1095	fd = get_unused_fd_flags(flags);
1096	if (fd >= 0) {
1097		struct file *f = do_filp_open(dfd, tmp, &op);
1098		if (IS_ERR(f)) {
1099			put_unused_fd(fd);
1100			fd = PTR_ERR(f);
1101		} else {
1102			fsnotify_open(f);
1103			fd_install(fd, f);
1104		}
1105	}
1106	putname(tmp);
1107	return fd;
1108}
1109
 
 
 
 
 
 
 
1110SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)
1111{
1112	if (force_o_largefile())
1113		flags |= O_LARGEFILE;
1114
1115	return do_sys_open(AT_FDCWD, filename, flags, mode);
1116}
1117
1118SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags,
1119		umode_t, mode)
1120{
1121	if (force_o_largefile())
1122		flags |= O_LARGEFILE;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1123
1124	return do_sys_open(dfd, filename, flags, mode);
 
 
 
 
1125}
1126
1127#ifdef CONFIG_COMPAT
1128/*
1129 * Exactly like sys_open(), except that it doesn't set the
1130 * O_LARGEFILE flag.
1131 */
1132COMPAT_SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)
1133{
1134	return do_sys_open(AT_FDCWD, filename, flags, mode);
1135}
1136
1137/*
1138 * Exactly like sys_openat(), except that it doesn't set the
1139 * O_LARGEFILE flag.
1140 */
1141COMPAT_SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags, umode_t, mode)
1142{
1143	return do_sys_open(dfd, filename, flags, mode);
1144}
1145#endif
1146
1147#ifndef __alpha__
1148
1149/*
1150 * For backward compatibility?  Maybe this should be moved
1151 * into arch/i386 instead?
1152 */
1153SYSCALL_DEFINE2(creat, const char __user *, pathname, umode_t, mode)
1154{
1155	return ksys_open(pathname, O_CREAT | O_WRONLY | O_TRUNC, mode);
 
 
 
 
1156}
1157
1158#endif
1159
1160/*
1161 * "id" is the POSIX thread ID. We use the
1162 * files pointer for this..
1163 */
1164int filp_close(struct file *filp, fl_owner_t id)
1165{
1166	int retval = 0;
1167
1168	if (!file_count(filp)) {
1169		printk(KERN_ERR "VFS: Close: file count is 0\n");
1170		return 0;
1171	}
1172
1173	if (filp->f_op->flush)
1174		retval = filp->f_op->flush(filp, id);
1175
1176	if (likely(!(filp->f_mode & FMODE_PATH))) {
1177		dnotify_flush(filp, id);
1178		locks_remove_posix(filp, id);
1179	}
1180	fput(filp);
1181	return retval;
1182}
1183
1184EXPORT_SYMBOL(filp_close);
1185
1186/*
1187 * Careful here! We test whether the file pointer is NULL before
1188 * releasing the fd. This ensures that one clone task can't release
1189 * an fd while another clone is opening it.
1190 */
1191SYSCALL_DEFINE1(close, unsigned int, fd)
1192{
1193	int retval = __close_fd(current->files, fd);
1194
1195	/* can't restart close syscall because file table entry was cleared */
1196	if (unlikely(retval == -ERESTARTSYS ||
1197		     retval == -ERESTARTNOINTR ||
1198		     retval == -ERESTARTNOHAND ||
1199		     retval == -ERESTART_RESTARTBLOCK))
1200		retval = -EINTR;
1201
1202	return retval;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1203}
1204
1205/*
1206 * This routine simulates a hangup on the tty, to arrange that users
1207 * are given clean terminals at login time.
1208 */
1209SYSCALL_DEFINE0(vhangup)
1210{
1211	if (capable(CAP_SYS_TTY_CONFIG)) {
1212		tty_vhangup_self();
1213		return 0;
1214	}
1215	return -EPERM;
1216}
1217
1218/*
1219 * Called when an inode is about to be open.
1220 * We use this to disallow opening large files on 32bit systems if
1221 * the caller didn't specify O_LARGEFILE.  On 64bit systems we force
1222 * on this flag in sys_open.
1223 */
1224int generic_file_open(struct inode * inode, struct file * filp)
1225{
1226	if (!(filp->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS)
1227		return -EOVERFLOW;
1228	return 0;
1229}
1230
1231EXPORT_SYMBOL(generic_file_open);
1232
1233/*
1234 * This is used by subsystems that don't want seekable
1235 * file descriptors. The function is not supposed to ever fail, the only
1236 * reason it returns an 'int' and not 'void' is so that it can be plugged
1237 * directly into file_operations structure.
1238 */
1239int nonseekable_open(struct inode *inode, struct file *filp)
1240{
1241	filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);
1242	return 0;
1243}
1244
1245EXPORT_SYMBOL(nonseekable_open);
1246
1247/*
1248 * stream_open is used by subsystems that want stream-like file descriptors.
1249 * Such file descriptors are not seekable and don't have notion of position
1250 * (file.f_pos is always 0 and ppos passed to .read()/.write() is always NULL).
1251 * Contrary to file descriptors of other regular files, .read() and .write()
1252 * can run simultaneously.
1253 *
1254 * stream_open never fails and is marked to return int so that it could be
1255 * directly used as file_operations.open .
1256 */
1257int stream_open(struct inode *inode, struct file *filp)
1258{
1259	filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE | FMODE_ATOMIC_POS);
1260	filp->f_mode |= FMODE_STREAM;
1261	return 0;
1262}
1263
1264EXPORT_SYMBOL(stream_open);