1/*
   2 *  linux/fs/open.c
   3 *
   4 *  Copyright (C) 1991, 1992  Linus Torvalds
   5 */
   6
   7#include <linux/string.h>
   8#include <linux/mm.h>
   9#include <linux/file.h>
  10#include <linux/fdtable.h>
  11#include <linux/fsnotify.h>
  12#include <linux/module.h>
  13#include <linux/tty.h>
  14#include <linux/namei.h>
  15#include <linux/backing-dev.h>
  16#include <linux/capability.h>
  17#include <linux/securebits.h>
  18#include <linux/security.h>
  19#include <linux/mount.h>
  20#include <linux/fcntl.h>
  21#include <linux/slab.h>
  22#include <asm/uaccess.h>
  23#include <linux/fs.h>
  24#include <linux/personality.h>
  25#include <linux/pagemap.h>
  26#include <linux/syscalls.h>
  27#include <linux/rcupdate.h>
  28#include <linux/audit.h>
  29#include <linux/falloc.h>
  30#include <linux/fs_struct.h>
  31#include <linux/ima.h>
  32#include <linux/dnotify.h>
  33
  34#include "internal.h"
  35
  36int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs,
  37	struct file *filp)
  38{
  39	int ret;
  40	struct iattr newattrs;
  41
  42	/* Not pretty: "inode->i_size" shouldn't really be signed. But it is. */
  43	if (length < 0)
  44		return -EINVAL;
  45
  46	newattrs.ia_size = length;
  47	newattrs.ia_valid = ATTR_SIZE | time_attrs;
  48	if (filp) {
  49		newattrs.ia_file = filp;
  50		newattrs.ia_valid |= ATTR_FILE;
  51	}
  52
  53	/* Remove suid/sgid on truncate too */
  54	ret = should_remove_suid(dentry);
  55	if (ret)
  56		newattrs.ia_valid |= ret | ATTR_FORCE;
  57
  58	mutex_lock(&dentry->d_inode->i_mutex);
  59	ret = notify_change(dentry, &newattrs);
  60	mutex_unlock(&dentry->d_inode->i_mutex);
  61	return ret;
  62}
  63
  64static long do_sys_truncate(const char __user *pathname, loff_t length)
  65{
  66	struct path path;
  67	struct inode *inode;
  68	int error;
  69
  70	error = -EINVAL;
  71	if (length < 0)	/* sorry, but loff_t says... */
  72		goto out;
  73
  74	error = user_path(pathname, &path);
  75	if (error)
  76		goto out;
  77	inode = path.dentry->d_inode;
  78
  79	/* For directories it's -EISDIR, for other non-regulars - -EINVAL */
  80	error = -EISDIR;
  81	if (S_ISDIR(inode->i_mode))
  82		goto dput_and_out;
  83
  84	error = -EINVAL;
  85	if (!S_ISREG(inode->i_mode))
  86		goto dput_and_out;
  87
  88	error = mnt_want_write(path.mnt);
  89	if (error)
  90		goto dput_and_out;
  91
  92	error = inode_permission(inode, MAY_WRITE);
  93	if (error)
  94		goto mnt_drop_write_and_out;
  95
  96	error = -EPERM;
  97	if (IS_APPEND(inode))
  98		goto mnt_drop_write_and_out;
  99
 100	error = get_write_access(inode);
 101	if (error)
 102		goto mnt_drop_write_and_out;
 103
 104	/*
 105	 * Make sure that there are no leases.  get_write_access() protects
 106	 * against the truncate racing with a lease-granting setlease().
 107	 */
 108	error = break_lease(inode, O_WRONLY);
 109	if (error)
 110		goto put_write_and_out;
 111
 112	error = locks_verify_truncate(inode, NULL, length);
 113	if (!error)
 114		error = security_path_truncate(&path);
 115	if (!error)
 116		error = do_truncate(path.dentry, length, 0, NULL);
 117
 118put_write_and_out:
 119	put_write_access(inode);
 120mnt_drop_write_and_out:
 121	mnt_drop_write(path.mnt);
 122dput_and_out:
 123	path_put(&path);
 124out:
 125	return error;
 126}
 127
 128SYSCALL_DEFINE2(truncate, const char __user *, path, long, length)
 129{
 130	return do_sys_truncate(path, length);
 131}
 132
 133static long do_sys_ftruncate(unsigned int fd, loff_t length, int small)
 134{
 135	struct inode * inode;
 136	struct dentry *dentry;
 137	struct file * file;
 138	int error;
 139
 140	error = -EINVAL;
 141	if (length < 0)
 142		goto out;
 143	error = -EBADF;
 144	file = fget(fd);
 145	if (!file)
 146		goto out;
 147
 148	/* explicitly opened as large or we are on 64-bit box */
 149	if (file->f_flags & O_LARGEFILE)
 150		small = 0;
 151
 152	dentry = file->f_path.dentry;
 153	inode = dentry->d_inode;
 154	error = -EINVAL;
 155	if (!S_ISREG(inode->i_mode) || !(file->f_mode & FMODE_WRITE))
 156		goto out_putf;
 157
 158	error = -EINVAL;
 159	/* Cannot ftruncate over 2^31 bytes without large file support */
 160	if (small && length > MAX_NON_LFS)
 161		goto out_putf;
 162
 163	error = -EPERM;
 164	if (IS_APPEND(inode))
 165		goto out_putf;
 166
 167	error = locks_verify_truncate(inode, file, length);
 168	if (!error)
 169		error = security_path_truncate(&file->f_path);
 170	if (!error)
 171		error = do_truncate(dentry, length, ATTR_MTIME|ATTR_CTIME, file);
 172out_putf:
 173	fput(file);
 174out:
 175	return error;
 176}
 177
 178SYSCALL_DEFINE2(ftruncate, unsigned int, fd, unsigned long, length)
 179{
 180	long ret = do_sys_ftruncate(fd, length, 1);
 181	/* avoid REGPARM breakage on x86: */
 182	asmlinkage_protect(2, ret, fd, length);
 183	return ret;
 184}
 185
 186/* LFS versions of truncate are only needed on 32 bit machines */
 187#if BITS_PER_LONG == 32
 188SYSCALL_DEFINE(truncate64)(const char __user * path, loff_t length)
 189{
 190	return do_sys_truncate(path, length);
 191}
 192#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
 193asmlinkage long SyS_truncate64(long path, loff_t length)
 194{
 195	return SYSC_truncate64((const char __user *) path, length);
 196}
 197SYSCALL_ALIAS(sys_truncate64, SyS_truncate64);
 198#endif
 199
 200SYSCALL_DEFINE(ftruncate64)(unsigned int fd, loff_t length)
 201{
 202	long ret = do_sys_ftruncate(fd, length, 0);
 203	/* avoid REGPARM breakage on x86: */
 204	asmlinkage_protect(2, ret, fd, length);
 205	return ret;
 206}
 207#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
 208asmlinkage long SyS_ftruncate64(long fd, loff_t length)
 209{
 210	return SYSC_ftruncate64((unsigned int) fd, length);
 211}
 212SYSCALL_ALIAS(sys_ftruncate64, SyS_ftruncate64);
 213#endif
 214#endif /* BITS_PER_LONG == 32 */
 215
 216
 217int do_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
 218{
 219	struct inode *inode = file->f_path.dentry->d_inode;
 220	long ret;
 221
 222	if (offset < 0 || len <= 0)
 223		return -EINVAL;
 224
 225	/* Return error if mode is not supported */
 226	if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
 227		return -EOPNOTSUPP;
 228
 229	/* Punch hole must have keep size set */
 230	if ((mode & FALLOC_FL_PUNCH_HOLE) &&
 231	    !(mode & FALLOC_FL_KEEP_SIZE))
 232		return -EOPNOTSUPP;
 233
 234	if (!(file->f_mode & FMODE_WRITE))
 235		return -EBADF;
 236
 237	/* It's not possible punch hole on append only file */
 238	if (mode & FALLOC_FL_PUNCH_HOLE && IS_APPEND(inode))
 239		return -EPERM;
 240
 241	if (IS_IMMUTABLE(inode))
 242		return -EPERM;
 243
 244	/*
 245	 * Revalidate the write permissions, in case security policy has
 246	 * changed since the files were opened.
 247	 */
 248	ret = security_file_permission(file, MAY_WRITE);
 249	if (ret)
 250		return ret;
 251
 252	if (S_ISFIFO(inode->i_mode))
 253		return -ESPIPE;
 254
 255	/*
 256	 * Let individual file system decide if it supports preallocation
 257	 * for directories or not.
 258	 */
 259	if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode))
 260		return -ENODEV;
 261
 262	/* Check for wrap through zero too */
 263	if (((offset + len) > inode->i_sb->s_maxbytes) || ((offset + len) < 0))
 264		return -EFBIG;
 265
 266	if (!file->f_op->fallocate)
 267		return -EOPNOTSUPP;
 268
 269	return file->f_op->fallocate(file, mode, offset, len);
 270}
 271
 272SYSCALL_DEFINE(fallocate)(int fd, int mode, loff_t offset, loff_t len)
 273{
 274	struct file *file;
 275	int error = -EBADF;
 276
 277	file = fget(fd);
 278	if (file) {
 279		error = do_fallocate(file, mode, offset, len);
 280		fput(file);
 281	}
 282
 283	return error;
 284}
 285
 286#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
 287asmlinkage long SyS_fallocate(long fd, long mode, loff_t offset, loff_t len)
 288{
 289	return SYSC_fallocate((int)fd, (int)mode, offset, len);
 290}
 291SYSCALL_ALIAS(sys_fallocate, SyS_fallocate);
 292#endif
 293
 294/*
 295 * access() needs to use the real uid/gid, not the effective uid/gid.
 296 * We do this by temporarily clearing all FS-related capabilities and
 297 * switching the fsuid/fsgid around to the real ones.
 298 */
 299SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode)
 300{
 301	const struct cred *old_cred;
 302	struct cred *override_cred;
 303	struct path path;
 304	struct inode *inode;
 305	int res;
 306
 307	if (mode & ~S_IRWXO)	/* where's F_OK, X_OK, W_OK, R_OK? */
 308		return -EINVAL;
 309
 310	override_cred = prepare_creds();
 311	if (!override_cred)
 312		return -ENOMEM;
 313
 314	override_cred->fsuid = override_cred->uid;
 315	override_cred->fsgid = override_cred->gid;
 316
 317	if (!issecure(SECURE_NO_SETUID_FIXUP)) {
 318		/* Clear the capabilities if we switch to a non-root user */
 319		kuid_t root_uid = make_kuid(override_cred->user_ns, 0);
 320		if (!uid_eq(override_cred->uid, root_uid))
 321			cap_clear(override_cred->cap_effective);
 322		else
 323			override_cred->cap_effective =
 324				override_cred->cap_permitted;
 325	}
 326
 327	old_cred = override_creds(override_cred);
 328
 329	res = user_path_at(dfd, filename, LOOKUP_FOLLOW, &path);
 330	if (res)
 331		goto out;
 332
 333	inode = path.dentry->d_inode;
 334
 335	if ((mode & MAY_EXEC) && S_ISREG(inode->i_mode)) {
 336		/*
 337		 * MAY_EXEC on regular files is denied if the fs is mounted
 338		 * with the "noexec" flag.
 339		 */
 340		res = -EACCES;
 341		if (path.mnt->mnt_flags & MNT_NOEXEC)
 342			goto out_path_release;
 343	}
 344
 345	res = inode_permission(inode, mode | MAY_ACCESS);
 346	/* SuS v2 requires we report a read only fs too */
 347	if (res || !(mode & S_IWOTH) || special_file(inode->i_mode))
 348		goto out_path_release;
 349	/*
 350	 * This is a rare case where using __mnt_is_readonly()
 351	 * is OK without a mnt_want/drop_write() pair.  Since
 352	 * no actual write to the fs is performed here, we do
 353	 * not need to telegraph to that to anyone.
 354	 *
 355	 * By doing this, we accept that this access is
 356	 * inherently racy and know that the fs may change
 357	 * state before we even see this result.
 358	 */
 359	if (__mnt_is_readonly(path.mnt))
 360		res = -EROFS;
 361
 362out_path_release:
 363	path_put(&path);
 364out:
 365	revert_creds(old_cred);
 366	put_cred(override_cred);
 367	return res;
 368}
 369
 370SYSCALL_DEFINE2(access, const char __user *, filename, int, mode)
 371{
 372	return sys_faccessat(AT_FDCWD, filename, mode);
 373}
 374
 375SYSCALL_DEFINE1(chdir, const char __user *, filename)
 376{
 377	struct path path;
 378	int error;
 379
 380	error = user_path_dir(filename, &path);
 381	if (error)
 382		goto out;
 383
 384	error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
 385	if (error)
 386		goto dput_and_out;
 387
 388	set_fs_pwd(current->fs, &path);
 389
 390dput_and_out:
 391	path_put(&path);
 392out:
 393	return error;
 394}
 395
 396SYSCALL_DEFINE1(fchdir, unsigned int, fd)
 397{
 398	struct file *file;
 399	struct inode *inode;
 400	int error, fput_needed;
 401
 402	error = -EBADF;
 403	file = fget_raw_light(fd, &fput_needed);
 404	if (!file)
 405		goto out;
 406
 407	inode = file->f_path.dentry->d_inode;
 408
 409	error = -ENOTDIR;
 410	if (!S_ISDIR(inode->i_mode))
 411		goto out_putf;
 412
 413	error = inode_permission(inode, MAY_EXEC | MAY_CHDIR);
 414	if (!error)
 415		set_fs_pwd(current->fs, &file->f_path);
 416out_putf:
 417	fput_light(file, fput_needed);
 418out:
 419	return error;
 420}
 421
 422SYSCALL_DEFINE1(chroot, const char __user *, filename)
 423{
 424	struct path path;
 425	int error;
 426
 427	error = user_path_dir(filename, &path);
 428	if (error)
 429		goto out;
 430
 431	error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
 432	if (error)
 433		goto dput_and_out;
 434
 435	error = -EPERM;
 436	if (!capable(CAP_SYS_CHROOT))
 437		goto dput_and_out;
 438	error = security_path_chroot(&path);
 439	if (error)
 440		goto dput_and_out;
 441
 442	set_fs_root(current->fs, &path);
 443	error = 0;
 444dput_and_out:
 445	path_put(&path);
 446out:
 447	return error;
 448}
 449
 450static int chmod_common(struct path *path, umode_t mode)
 451{
 452	struct inode *inode = path->dentry->d_inode;
 453	struct iattr newattrs;
 454	int error;
 455
 456	error = mnt_want_write(path->mnt);
 457	if (error)
 458		return error;
 459	mutex_lock(&inode->i_mutex);
 460	error = security_path_chmod(path, mode);
 461	if (error)
 462		goto out_unlock;
 463	newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
 464	newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
 465	error = notify_change(path->dentry, &newattrs);
 466out_unlock:
 467	mutex_unlock(&inode->i_mutex);
 468	mnt_drop_write(path->mnt);
 469	return error;
 470}
 471
 472SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode)
 473{
 474	struct file * file;
 475	int err = -EBADF;
 476
 477	file = fget(fd);
 478	if (file) {
 479		audit_inode(NULL, file->f_path.dentry);
 480		err = chmod_common(&file->f_path, mode);
 481		fput(file);
 482	}
 483	return err;
 484}
 485
 486SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename, umode_t, mode)
 487{
 488	struct path path;
 489	int error;
 490
 491	error = user_path_at(dfd, filename, LOOKUP_FOLLOW, &path);
 492	if (!error) {
 493		error = chmod_common(&path, mode);
 494		path_put(&path);
 495	}
 496	return error;
 497}
 498
 499SYSCALL_DEFINE2(chmod, const char __user *, filename, umode_t, mode)
 500{
 501	return sys_fchmodat(AT_FDCWD, filename, mode);
 502}
 503
 504static int chown_common(struct path *path, uid_t user, gid_t group)
 505{
 506	struct inode *inode = path->dentry->d_inode;
 507	int error;
 508	struct iattr newattrs;
 509	kuid_t uid;
 510	kgid_t gid;
 511
 512	uid = make_kuid(current_user_ns(), user);
 513	gid = make_kgid(current_user_ns(), group);
 514
 515	newattrs.ia_valid =  ATTR_CTIME;
 516	if (user != (uid_t) -1) {
 517		if (!uid_valid(uid))
 518			return -EINVAL;
 519		newattrs.ia_valid |= ATTR_UID;
 520		newattrs.ia_uid = uid;
 521	}
 522	if (group != (gid_t) -1) {
 523		if (!gid_valid(gid))
 524			return -EINVAL;
 525		newattrs.ia_valid |= ATTR_GID;
 526		newattrs.ia_gid = gid;
 527	}
 528	if (!S_ISDIR(inode->i_mode))
 529		newattrs.ia_valid |=
 530			ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_KILL_PRIV;
 531	mutex_lock(&inode->i_mutex);
 532	error = security_path_chown(path, user, group);
 533	if (!error)
 534		error = notify_change(path->dentry, &newattrs);
 535	mutex_unlock(&inode->i_mutex);
 536
 537	return error;
 538}
 539
 540SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group)
 541{
 542	struct path path;
 543	int error;
 544
 545	error = user_path(filename, &path);
 546	if (error)
 547		goto out;
 548	error = mnt_want_write(path.mnt);
 549	if (error)
 550		goto out_release;
 551	error = chown_common(&path, user, group);
 552	mnt_drop_write(path.mnt);
 553out_release:
 554	path_put(&path);
 555out:
 556	return error;
 557}
 558
 559SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user,
 560		gid_t, group, int, flag)
 561{
 562	struct path path;
 563	int error = -EINVAL;
 564	int lookup_flags;
 565
 566	if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
 567		goto out;
 568
 569	lookup_flags = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
 570	if (flag & AT_EMPTY_PATH)
 571		lookup_flags |= LOOKUP_EMPTY;
 572	error = user_path_at(dfd, filename, lookup_flags, &path);
 573	if (error)
 574		goto out;
 575	error = mnt_want_write(path.mnt);
 576	if (error)
 577		goto out_release;
 578	error = chown_common(&path, user, group);
 579	mnt_drop_write(path.mnt);
 580out_release:
 581	path_put(&path);
 582out:
 583	return error;
 584}
 585
 586SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group)
 587{
 588	struct path path;
 589	int error;
 590
 591	error = user_lpath(filename, &path);
 592	if (error)
 593		goto out;
 594	error = mnt_want_write(path.mnt);
 595	if (error)
 596		goto out_release;
 597	error = chown_common(&path, user, group);
 598	mnt_drop_write(path.mnt);
 599out_release:
 600	path_put(&path);
 601out:
 602	return error;
 603}
 604
 605SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group)
 606{
 607	struct file * file;
 608	int error = -EBADF;
 609	struct dentry * dentry;
 610
 611	file = fget(fd);
 612	if (!file)
 613		goto out;
 614
 615	error = mnt_want_write_file(file);
 616	if (error)
 617		goto out_fput;
 618	dentry = file->f_path.dentry;
 619	audit_inode(NULL, dentry);
 620	error = chown_common(&file->f_path, user, group);
 621	mnt_drop_write_file(file);
 622out_fput:
 623	fput(file);
 624out:
 625	return error;
 626}
 627
 628/*
 629 * You have to be very careful that these write
 630 * counts get cleaned up in error cases and
 631 * upon __fput().  This should probably never
 632 * be called outside of __dentry_open().
 633 */
 634static inline int __get_file_write_access(struct inode *inode,
 635					  struct vfsmount *mnt)
 636{
 637	int error;
 638	error = get_write_access(inode);
 639	if (error)
 640		return error;
 641	/*
 642	 * Do not take mount writer counts on
 643	 * special files since no writes to
 644	 * the mount itself will occur.
 645	 */
 646	if (!special_file(inode->i_mode)) {
 647		/*
 648		 * Balanced in __fput()
 649		 */
 650		error = mnt_want_write(mnt);
 651		if (error)
 652			put_write_access(inode);
 653	}
 654	return error;
 655}
 656
 657int open_check_o_direct(struct file *f)
 658{
 659	/* NB: we're sure to have correct a_ops only after f_op->open */
 660	if (f->f_flags & O_DIRECT) {
 661		if (!f->f_mapping->a_ops ||
 662		    ((!f->f_mapping->a_ops->direct_IO) &&
 663		    (!f->f_mapping->a_ops->get_xip_mem))) {
 664			return -EINVAL;
 665		}
 666	}
 667	return 0;
 668}
 669
 670static struct file *do_dentry_open(struct dentry *dentry, struct vfsmount *mnt,
 671				   struct file *f,
 672				   int (*open)(struct inode *, struct file *),
 673				   const struct cred *cred)
 674{
 675	static const struct file_operations empty_fops = {};
 676	struct inode *inode;
 677	int error;
 678
 679	f->f_mode = OPEN_FMODE(f->f_flags) | FMODE_LSEEK |
 680				FMODE_PREAD | FMODE_PWRITE;
 681
 682	if (unlikely(f->f_flags & O_PATH))
 683		f->f_mode = FMODE_PATH;
 684
 685	inode = dentry->d_inode;
 686	if (f->f_mode & FMODE_WRITE) {
 687		error = __get_file_write_access(inode, mnt);
 688		if (error)
 689			goto cleanup_file;
 690		if (!special_file(inode->i_mode))
 691			file_take_write(f);
 692	}
 693
 694	f->f_mapping = inode->i_mapping;
 695	f->f_path.dentry = dentry;
 696	f->f_path.mnt = mnt;
 697	f->f_pos = 0;
 698	file_sb_list_add(f, inode->i_sb);
 699
 700	if (unlikely(f->f_mode & FMODE_PATH)) {
 701		f->f_op = &empty_fops;
 702		return f;
 703	}
 704
 705	f->f_op = fops_get(inode->i_fop);
 706
 707	error = security_file_open(f, cred);
 708	if (error)
 709		goto cleanup_all;
 710
 711	error = break_lease(inode, f->f_flags);
 712	if (error)
 713		goto cleanup_all;
 714
 715	if (!open && f->f_op)
 716		open = f->f_op->open;
 717	if (open) {
 718		error = open(inode, f);
 719		if (error)
 720			goto cleanup_all;
 721	}
 722	if ((f->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
 723		i_readcount_inc(inode);
 724
 725	f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
 726
 727	file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);
 728
 
 
 
 
 
 
 
 
 
 
 729	return f;
 730
 731cleanup_all:
 732	fops_put(f->f_op);
 733	if (f->f_mode & FMODE_WRITE) {
 734		put_write_access(inode);
 735		if (!special_file(inode->i_mode)) {
 736			/*
 737			 * We don't consider this a real
 738			 * mnt_want/drop_write() pair
 739			 * because it all happenend right
 740			 * here, so just reset the state.
 741			 */
 742			file_reset_write(f);
 743			mnt_drop_write(mnt);
 744		}
 745	}
 746	file_sb_list_del(f);
 747	f->f_path.dentry = NULL;
 748	f->f_path.mnt = NULL;
 749cleanup_file:
 
 750	dput(dentry);
 751	mntput(mnt);
 752	return ERR_PTR(error);
 753}
 754
 755static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
 756				struct file *f,
 757				int (*open)(struct inode *, struct file *),
 758				const struct cred *cred)
 759{
 760	struct file *res = do_dentry_open(dentry, mnt, f, open, cred);
 761	if (!IS_ERR(res)) {
 762		int error = open_check_o_direct(f);
 763		if (error) {
 764			fput(res);
 765			res = ERR_PTR(error);
 766		}
 767	} else {
 768		put_filp(f);
 769	}
 770	return res;
 771}
 772
 773/**
 774 * lookup_instantiate_filp - instantiates the open intent filp
 775 * @nd: pointer to nameidata
 776 * @dentry: pointer to dentry
 777 * @open: open callback
 778 *
 779 * Helper for filesystems that want to use lookup open intents and pass back
 780 * a fully instantiated struct file to the caller.
 781 * This function is meant to be called from within a filesystem's
 782 * lookup method.
 783 * Beware of calling it for non-regular files! Those ->open methods might block
 784 * (e.g. in fifo_open), leaving you with parent locked (and in case of fifo,
 785 * leading to a deadlock, as nobody can open that fifo anymore, because
 786 * another process to open fifo will block on locked parent when doing lookup).
 787 * Note that in case of error, nd->intent.open.file is destroyed, but the
 788 * path information remains valid.
 789 * If the open callback is set to NULL, then the standard f_op->open()
 790 * filesystem callback is substituted.
 791 */
 792struct file *lookup_instantiate_filp(struct nameidata *nd, struct dentry *dentry,
 793		int (*open)(struct inode *, struct file *))
 794{
 795	const struct cred *cred = current_cred();
 796
 797	if (IS_ERR(nd->intent.open.file))
 798		goto out;
 799	if (IS_ERR(dentry))
 800		goto out_err;
 801	nd->intent.open.file = __dentry_open(dget(dentry), mntget(nd->path.mnt),
 802					     nd->intent.open.file,
 803					     open, cred);
 804out:
 805	return nd->intent.open.file;
 806out_err:
 807	release_open_intent(nd);
 808	nd->intent.open.file = ERR_CAST(dentry);
 809	goto out;
 810}
 811EXPORT_SYMBOL_GPL(lookup_instantiate_filp);
 812
 813/**
 814 * nameidata_to_filp - convert a nameidata to an open filp.
 815 * @nd: pointer to nameidata
 816 * @flags: open flags
 817 *
 818 * Note that this function destroys the original nameidata
 819 */
 820struct file *nameidata_to_filp(struct nameidata *nd)
 821{
 822	const struct cred *cred = current_cred();
 823	struct file *filp;
 824
 825	/* Pick up the filp from the open intent */
 826	filp = nd->intent.open.file;
 
 827
 828	/* Has the filesystem initialised the file for us? */
 829	if (filp->f_path.dentry != NULL) {
 830		nd->intent.open.file = NULL;
 831	} else {
 832		struct file *res;
 833
 834		path_get(&nd->path);
 835		res = do_dentry_open(nd->path.dentry, nd->path.mnt,
 836				     filp, NULL, cred);
 837		if (!IS_ERR(res)) {
 838			int error;
 839
 840			nd->intent.open.file = NULL;
 841			BUG_ON(res != filp);
 842
 843			error = open_check_o_direct(filp);
 844			if (error) {
 845				fput(filp);
 846				filp = ERR_PTR(error);
 847			}
 848		} else {
 849			/* Allow nd->intent.open.file to be recycled */
 850			filp = res;
 851		}
 852	}
 853	return filp;
 854}
 855
 856/*
 857 * dentry_open() will have done dput(dentry) and mntput(mnt) if it returns an
 858 * error.
 859 */
 860struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags,
 861			 const struct cred *cred)
 862{
 863	int error;
 864	struct file *f;
 865
 866	validate_creds(cred);
 867
 868	/* We must always pass in a valid mount pointer. */
 869	BUG_ON(!mnt);
 870
 871	error = -ENFILE;
 872	f = get_empty_filp();
 873	if (f == NULL) {
 874		dput(dentry);
 875		mntput(mnt);
 876		return ERR_PTR(error);
 877	}
 878
 879	f->f_flags = flags;
 880	return __dentry_open(dentry, mnt, f, NULL, cred);
 881}
 882EXPORT_SYMBOL(dentry_open);
 883
 884static void __put_unused_fd(struct files_struct *files, unsigned int fd)
 885{
 886	struct fdtable *fdt = files_fdtable(files);
 887	__clear_open_fd(fd, fdt);
 888	if (fd < files->next_fd)
 889		files->next_fd = fd;
 890}
 891
 892void put_unused_fd(unsigned int fd)
 893{
 894	struct files_struct *files = current->files;
 895	spin_lock(&files->file_lock);
 896	__put_unused_fd(files, fd);
 897	spin_unlock(&files->file_lock);
 898}
 899
 900EXPORT_SYMBOL(put_unused_fd);
 901
 902/*
 903 * Install a file pointer in the fd array.
 904 *
 905 * The VFS is full of places where we drop the files lock between
 906 * setting the open_fds bitmap and installing the file in the file
 907 * array.  At any such point, we are vulnerable to a dup2() race
 908 * installing a file in the array before us.  We need to detect this and
 909 * fput() the struct file we are about to overwrite in this case.
 910 *
 911 * It should never happen - if we allow dup2() do it, _really_ bad things
 912 * will follow.
 913 */
 914
 915void fd_install(unsigned int fd, struct file *file)
 916{
 917	struct files_struct *files = current->files;
 918	struct fdtable *fdt;
 919	spin_lock(&files->file_lock);
 920	fdt = files_fdtable(files);
 921	BUG_ON(fdt->fd[fd] != NULL);
 922	rcu_assign_pointer(fdt->fd[fd], file);
 923	spin_unlock(&files->file_lock);
 924}
 925
 926EXPORT_SYMBOL(fd_install);
 927
 928static inline int build_open_flags(int flags, umode_t mode, struct open_flags *op)
 929{
 930	int lookup_flags = 0;
 931	int acc_mode;
 932
 933	if (flags & O_CREAT)
 934		op->mode = (mode & S_IALLUGO) | S_IFREG;
 935	else
 936		op->mode = 0;
 937
 938	/* Must never be set by userspace */
 939	flags &= ~FMODE_NONOTIFY;
 940
 941	/*
 942	 * O_SYNC is implemented as __O_SYNC|O_DSYNC.  As many places only
 943	 * check for O_DSYNC if the need any syncing at all we enforce it's
 944	 * always set instead of having to deal with possibly weird behaviour
 945	 * for malicious applications setting only __O_SYNC.
 946	 */
 947	if (flags & __O_SYNC)
 948		flags |= O_DSYNC;
 949
 950	/*
 951	 * If we have O_PATH in the open flag. Then we
 952	 * cannot have anything other than the below set of flags
 953	 */
 954	if (flags & O_PATH) {
 955		flags &= O_DIRECTORY | O_NOFOLLOW | O_PATH;
 956		acc_mode = 0;
 957	} else {
 958		acc_mode = MAY_OPEN | ACC_MODE(flags);
 959	}
 960
 961	op->open_flag = flags;
 962
 963	/* O_TRUNC implies we need access checks for write permissions */
 964	if (flags & O_TRUNC)
 965		acc_mode |= MAY_WRITE;
 966
 967	/* Allow the LSM permission hook to distinguish append
 968	   access from general write access. */
 969	if (flags & O_APPEND)
 970		acc_mode |= MAY_APPEND;
 971
 972	op->acc_mode = acc_mode;
 973
 974	op->intent = flags & O_PATH ? 0 : LOOKUP_OPEN;
 975
 976	if (flags & O_CREAT) {
 977		op->intent |= LOOKUP_CREATE;
 978		if (flags & O_EXCL)
 979			op->intent |= LOOKUP_EXCL;
 980	}
 981
 982	if (flags & O_DIRECTORY)
 983		lookup_flags |= LOOKUP_DIRECTORY;
 984	if (!(flags & O_NOFOLLOW))
 985		lookup_flags |= LOOKUP_FOLLOW;
 986	return lookup_flags;
 987}
 988
 989/**
 990 * filp_open - open file and return file pointer
 991 *
 992 * @filename:	path to open
 993 * @flags:	open flags as per the open(2) second argument
 994 * @mode:	mode for the new file if O_CREAT is set, else ignored
 995 *
 996 * This is the helper to open a file from kernelspace if you really
 997 * have to.  But in generally you should not do this, so please move
 998 * along, nothing to see here..
 999 */
1000struct file *filp_open(const char *filename, int flags, umode_t mode)
1001{
1002	struct open_flags op;
1003	int lookup = build_open_flags(flags, mode, &op);
1004	return do_filp_open(AT_FDCWD, filename, &op, lookup);
1005}
1006EXPORT_SYMBOL(filp_open);
1007
1008struct file *file_open_root(struct dentry *dentry, struct vfsmount *mnt,
1009			    const char *filename, int flags)
1010{
1011	struct open_flags op;
1012	int lookup = build_open_flags(flags, 0, &op);
1013	if (flags & O_CREAT)
1014		return ERR_PTR(-EINVAL);
1015	if (!filename && (flags & O_DIRECTORY))
1016		if (!dentry->d_inode->i_op->lookup)
1017			return ERR_PTR(-ENOTDIR);
1018	return do_file_open_root(dentry, mnt, filename, &op, lookup);
1019}
1020EXPORT_SYMBOL(file_open_root);
1021
1022long do_sys_open(int dfd, const char __user *filename, int flags, umode_t mode)
1023{
1024	struct open_flags op;
1025	int lookup = build_open_flags(flags, mode, &op);
1026	char *tmp = getname(filename);
1027	int fd = PTR_ERR(tmp);
1028
1029	if (!IS_ERR(tmp)) {
1030		fd = get_unused_fd_flags(flags);
1031		if (fd >= 0) {
1032			struct file *f = do_filp_open(dfd, tmp, &op, lookup);
1033			if (IS_ERR(f)) {
1034				put_unused_fd(fd);
1035				fd = PTR_ERR(f);
1036			} else {
1037				fsnotify_open(f);
1038				fd_install(fd, f);
1039			}
1040		}
1041		putname(tmp);
1042	}
1043	return fd;
1044}
1045
1046SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)
1047{
1048	long ret;
1049
1050	if (force_o_largefile())
1051		flags |= O_LARGEFILE;
1052
1053	ret = do_sys_open(AT_FDCWD, filename, flags, mode);
1054	/* avoid REGPARM breakage on x86: */
1055	asmlinkage_protect(3, ret, filename, flags, mode);
1056	return ret;
1057}
1058
1059SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags,
1060		umode_t, mode)
1061{
1062	long ret;
1063
1064	if (force_o_largefile())
1065		flags |= O_LARGEFILE;
1066
1067	ret = do_sys_open(dfd, filename, flags, mode);
1068	/* avoid REGPARM breakage on x86: */
1069	asmlinkage_protect(4, ret, dfd, filename, flags, mode);
1070	return ret;
1071}
1072
1073#ifndef __alpha__
1074
1075/*
1076 * For backward compatibility?  Maybe this should be moved
1077 * into arch/i386 instead?
1078 */
1079SYSCALL_DEFINE2(creat, const char __user *, pathname, umode_t, mode)
1080{
1081	return sys_open(pathname, O_CREAT | O_WRONLY | O_TRUNC, mode);
1082}
1083
1084#endif
1085
1086/*
1087 * "id" is the POSIX thread ID. We use the
1088 * files pointer for this..
1089 */
1090int filp_close(struct file *filp, fl_owner_t id)
1091{
1092	int retval = 0;
1093
1094	if (!file_count(filp)) {
1095		printk(KERN_ERR "VFS: Close: file count is 0\n");
1096		return 0;
1097	}
1098
1099	if (filp->f_op && filp->f_op->flush)
1100		retval = filp->f_op->flush(filp, id);
1101
1102	if (likely(!(filp->f_mode & FMODE_PATH))) {
1103		dnotify_flush(filp, id);
1104		locks_remove_posix(filp, id);
1105	}
1106	fput(filp);
1107	return retval;
1108}
1109
1110EXPORT_SYMBOL(filp_close);
1111
1112/*
1113 * Careful here! We test whether the file pointer is NULL before
1114 * releasing the fd. This ensures that one clone task can't release
1115 * an fd while another clone is opening it.
1116 */
1117SYSCALL_DEFINE1(close, unsigned int, fd)
1118{
1119	struct file * filp;
1120	struct files_struct *files = current->files;
1121	struct fdtable *fdt;
1122	int retval;
1123
1124	spin_lock(&files->file_lock);
1125	fdt = files_fdtable(files);
1126	if (fd >= fdt->max_fds)
1127		goto out_unlock;
1128	filp = fdt->fd[fd];
1129	if (!filp)
1130		goto out_unlock;
1131	rcu_assign_pointer(fdt->fd[fd], NULL);
1132	__clear_close_on_exec(fd, fdt);
1133	__put_unused_fd(files, fd);
1134	spin_unlock(&files->file_lock);
1135	retval = filp_close(filp, files);
1136
1137	/* can't restart close syscall because file table entry was cleared */
1138	if (unlikely(retval == -ERESTARTSYS ||
1139		     retval == -ERESTARTNOINTR ||
1140		     retval == -ERESTARTNOHAND ||
1141		     retval == -ERESTART_RESTARTBLOCK))
1142		retval = -EINTR;
1143
1144	return retval;
1145
1146out_unlock:
1147	spin_unlock(&files->file_lock);
1148	return -EBADF;
1149}
1150EXPORT_SYMBOL(sys_close);
1151
1152/*
1153 * This routine simulates a hangup on the tty, to arrange that users
1154 * are given clean terminals at login time.
1155 */
1156SYSCALL_DEFINE0(vhangup)
1157{
1158	if (capable(CAP_SYS_TTY_CONFIG)) {
1159		tty_vhangup_self();
1160		return 0;
1161	}
1162	return -EPERM;
1163}
1164
1165/*
1166 * Called when an inode is about to be open.
1167 * We use this to disallow opening large files on 32bit systems if
1168 * the caller didn't specify O_LARGEFILE.  On 64bit systems we force
1169 * on this flag in sys_open.
1170 */
1171int generic_file_open(struct inode * inode, struct file * filp)
1172{
1173	if (!(filp->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS)
1174		return -EOVERFLOW;
1175	return 0;
1176}
1177
1178EXPORT_SYMBOL(generic_file_open);
1179
1180/*
1181 * This is used by subsystems that don't want seekable
1182 * file descriptors. The function is not supposed to ever fail, the only
1183 * reason it returns an 'int' and not 'void' is so that it can be plugged
1184 * directly into file_operations structure.
1185 */
1186int nonseekable_open(struct inode *inode, struct file *filp)
1187{
1188	filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);
1189	return 0;
1190}
1191
1192EXPORT_SYMBOL(nonseekable_open);