namei.c 68.7 KB
Newer Older
L
Linus Torvalds 已提交
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
/*
 *  linux/fs/namei.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 */

/*
 * Some corrections by tytso.
 */

/* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname
 * lookup logic.
 */
/* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture.
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/namei.h>
#include <linux/quotaops.h>
#include <linux/pagemap.h>
R
Robert Love 已提交
24
#include <linux/fsnotify.h>
L
Linus Torvalds 已提交
25 26 27 28 29
#include <linux/personality.h>
#include <linux/security.h>
#include <linux/syscalls.h>
#include <linux/mount.h>
#include <linux/audit.h>
30
#include <linux/capability.h>
31
#include <linux/file.h>
32 33
#include <linux/fcntl.h>
#include <linux/namei.h>
L
Linus Torvalds 已提交
34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105
#include <asm/namei.h>
#include <asm/uaccess.h>

#define ACC_MODE(x) ("\000\004\002\006"[(x)&O_ACCMODE])

/* [Feb-1997 T. Schoebel-Theuer]
 * Fundamental changes in the pathname lookup mechanisms (namei)
 * were necessary because of omirr.  The reason is that omirr needs
 * to know the _real_ pathname, not the user-supplied one, in case
 * of symlinks (and also when transname replacements occur).
 *
 * The new code replaces the old recursive symlink resolution with
 * an iterative one (in case of non-nested symlink chains).  It does
 * this with calls to <fs>_follow_link().
 * As a side effect, dir_namei(), _namei() and follow_link() are now 
 * replaced with a single function lookup_dentry() that can handle all 
 * the special cases of the former code.
 *
 * With the new dcache, the pathname is stored at each inode, at least as
 * long as the refcount of the inode is positive.  As a side effect, the
 * size of the dcache depends on the inode cache and thus is dynamic.
 *
 * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink
 * resolution to correspond with current state of the code.
 *
 * Note that the symlink resolution is not *completely* iterative.
 * There is still a significant amount of tail- and mid- recursion in
 * the algorithm.  Also, note that <fs>_readlink() is not used in
 * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink()
 * may return different results than <fs>_follow_link().  Many virtual
 * filesystems (including /proc) exhibit this behavior.
 */

/* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation:
 * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL
 * and the name already exists in form of a symlink, try to create the new
 * name indicated by the symlink. The old code always complained that the
 * name already exists, due to not following the symlink even if its target
 * is nonexistent.  The new semantics affects also mknod() and link() when
 * the name is a symlink pointing to a non-existant name.
 *
 * I don't know which semantics is the right one, since I have no access
 * to standards. But I found by trial that HP-UX 9.0 has the full "new"
 * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the
 * "old" one. Personally, I think the new semantics is much more logical.
 * Note that "ln old new" where "new" is a symlink pointing to a non-existing
 * file does succeed in both HP-UX and SunOs, but not in Solaris
 * and in the old Linux semantics.
 */

/* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink
 * semantics.  See the comments in "open_namei" and "do_link" below.
 *
 * [10-Sep-98 Alan Modra] Another symlink change.
 */

/* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks:
 *	inside the path - always follow.
 *	in the last component in creation/removal/renaming - never follow.
 *	if LOOKUP_FOLLOW passed - follow.
 *	if the pathname has trailing slashes - follow.
 *	otherwise - don't follow.
 * (applied in that order).
 *
 * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT
 * restored for 2.4. This is the last surviving part of old 4.2BSD bug.
 * During the 2.4 we need to fix the userland stuff depending on it -
 * hopefully we will be able to get rid of that wart in 2.5. So far only
 * XEmacs seems to be relying on it...
 */
/*
 * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland)
106
 * implemented.  Let's see if raised priority of ->s_vfs_rename_mutex gives
L
Linus Torvalds 已提交
107 108 109 110 111 112 113 114 115 116
 * any extra contention...
 */

/* In order to reduce some races, while at the same time doing additional
 * checking and hopefully speeding things up, we copy filenames to the
 * kernel data space before using them..
 *
 * POSIX.1 2.4: an empty pathname is invalid (ENOENT).
 * PATH_MAX includes the nul terminator --RR.
 */
117
static int do_getname(const char __user *filename, char *page)
L
Linus Torvalds 已提交
118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160
{
	int retval;
	unsigned long len = PATH_MAX;

	if (!segment_eq(get_fs(), KERNEL_DS)) {
		if ((unsigned long) filename >= TASK_SIZE)
			return -EFAULT;
		if (TASK_SIZE - (unsigned long) filename < PATH_MAX)
			len = TASK_SIZE - (unsigned long) filename;
	}

	retval = strncpy_from_user(page, filename, len);
	if (retval > 0) {
		if (retval < len)
			return 0;
		return -ENAMETOOLONG;
	} else if (!retval)
		retval = -ENOENT;
	return retval;
}

char * getname(const char __user * filename)
{
	char *tmp, *result;

	result = ERR_PTR(-ENOMEM);
	tmp = __getname();
	if (tmp)  {
		int retval = do_getname(filename, tmp);

		result = tmp;
		if (retval < 0) {
			__putname(tmp);
			result = ERR_PTR(retval);
		}
	}
	audit_getname(result);
	return result;
}

#ifdef CONFIG_AUDITSYSCALL
void putname(const char *name)
{
161
	if (unlikely(!audit_dummy_context()))
L
Linus Torvalds 已提交
162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228
		audit_putname(name);
	else
		__putname(name);
}
EXPORT_SYMBOL(putname);
#endif


/**
 * generic_permission  -  check for access rights on a Posix-like filesystem
 * @inode:	inode to check access rights for
 * @mask:	right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
 * @check_acl:	optional callback to check for Posix ACLs
 *
 * Used to check for read/write/execute permissions on a file.
 * We use "fsuid" for this, letting us set arbitrary permissions
 * for filesystem access without changing the "normal" uids which
 * are used for other things..
 */
int generic_permission(struct inode *inode, int mask,
		int (*check_acl)(struct inode *inode, int mask))
{
	umode_t			mode = inode->i_mode;

	if (current->fsuid == inode->i_uid)
		mode >>= 6;
	else {
		if (IS_POSIXACL(inode) && (mode & S_IRWXG) && check_acl) {
			int error = check_acl(inode, mask);
			if (error == -EACCES)
				goto check_capabilities;
			else if (error != -EAGAIN)
				return error;
		}

		if (in_group_p(inode->i_gid))
			mode >>= 3;
	}

	/*
	 * If the DACs are ok we don't need any capability check.
	 */
	if (((mode & mask & (MAY_READ|MAY_WRITE|MAY_EXEC)) == mask))
		return 0;

 check_capabilities:
	/*
	 * Read/write DACs are always overridable.
	 * Executable DACs are overridable if at least one exec bit is set.
	 */
	if (!(mask & MAY_EXEC) ||
	    (inode->i_mode & S_IXUGO) || S_ISDIR(inode->i_mode))
		if (capable(CAP_DAC_OVERRIDE))
			return 0;

	/*
	 * Searching includes executable on directories, else just read.
	 */
	if (mask == MAY_READ || (S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE)))
		if (capable(CAP_DAC_READ_SEARCH))
			return 0;

	return -EACCES;
}

int permission(struct inode *inode, int mask, struct nameidata *nd)
{
229
	umode_t mode = inode->i_mode;
L
Linus Torvalds 已提交
230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248
	int retval, submask;

	if (mask & MAY_WRITE) {

		/*
		 * Nobody gets write access to a read-only fs.
		 */
		if (IS_RDONLY(inode) &&
		    (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
			return -EROFS;

		/*
		 * Nobody gets write access to an immutable file.
		 */
		if (IS_IMMUTABLE(inode))
			return -EACCES;
	}


249 250
	/*
	 * MAY_EXEC on regular files requires special handling: We override
251 252
	 * filesystem execute permissions if the mode bits aren't set or
	 * the fs is mounted with the "noexec" flag.
253
	 */
254 255
	if ((mask & MAY_EXEC) && S_ISREG(mode) && (!(mode & S_IXUGO) ||
			(nd && nd->mnt && (nd->mnt->mnt_flags & MNT_NOEXEC))))
256 257
		return -EACCES;

L
Linus Torvalds 已提交
258 259 260 261 262 263 264 265 266 267 268 269
	/* Ordinary permission routines do not understand MAY_APPEND. */
	submask = mask & ~MAY_APPEND;
	if (inode->i_op && inode->i_op->permission)
		retval = inode->i_op->permission(inode, submask, nd);
	else
		retval = generic_permission(inode, submask, NULL);
	if (retval)
		return retval;

	return security_inode_permission(inode, mask, nd);
}

270 271 272 273 274 275 276 277 278 279 280 281 282 283 284
/**
 * vfs_permission  -  check for access rights to a given path
 * @nd:		lookup result that describes the path
 * @mask:	right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
 *
 * Used to check for read/write/execute permissions on a path.
 * We use "fsuid" for this, letting us set arbitrary permissions
 * for filesystem access without changing the "normal" uids which
 * are used for other things.
 */
int vfs_permission(struct nameidata *nd, int mask)
{
	return permission(nd->dentry->d_inode, mask, nd);
}

285 286 287 288 289 290 291 292 293 294 295 296 297 298
/**
 * file_permission  -  check for additional access rights to a given file
 * @file:	file to check access rights for
 * @mask:	right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
 *
 * Used to check for read/write/execute permissions on an already opened
 * file.
 *
 * Note:
 *	Do not use this function in new code.  All access checks should
 *	be done using vfs_permission().
 */
int file_permission(struct file *file, int mask)
{
299
	return permission(file->f_path.dentry->d_inode, mask, NULL);
300 301
}

L
Linus Torvalds 已提交
302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334
/*
 * get_write_access() gets write permission for a file.
 * put_write_access() releases this write permission.
 * This is used for regular files.
 * We cannot support write (and maybe mmap read-write shared) accesses and
 * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode
 * can have the following values:
 * 0: no writers, no VM_DENYWRITE mappings
 * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist
 * > 0: (i_writecount) users are writing to the file.
 *
 * Normally we operate on that counter with atomic_{inc,dec} and it's safe
 * except for the cases where we don't hold i_writecount yet. Then we need to
 * use {get,deny}_write_access() - these functions check the sign and refuse
 * to do the change if sign is wrong. Exclusion between them is provided by
 * the inode->i_lock spinlock.
 */

int get_write_access(struct inode * inode)
{
	spin_lock(&inode->i_lock);
	if (atomic_read(&inode->i_writecount) < 0) {
		spin_unlock(&inode->i_lock);
		return -ETXTBSY;
	}
	atomic_inc(&inode->i_writecount);
	spin_unlock(&inode->i_lock);

	return 0;
}

int deny_write_access(struct file * file)
{
335
	struct inode *inode = file->f_path.dentry->d_inode;
L
Linus Torvalds 已提交
336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360

	spin_lock(&inode->i_lock);
	if (atomic_read(&inode->i_writecount) > 0) {
		spin_unlock(&inode->i_lock);
		return -ETXTBSY;
	}
	atomic_dec(&inode->i_writecount);
	spin_unlock(&inode->i_lock);

	return 0;
}

void path_release(struct nameidata *nd)
{
	dput(nd->dentry);
	mntput(nd->mnt);
}

/*
 * umount() mustn't call path_release()/mntput() as that would clear
 * mnt_expiry_mark
 */
void path_release_on_umount(struct nameidata *nd)
{
	dput(nd->dentry);
361
	mntput_no_expire(nd->mnt);
L
Linus Torvalds 已提交
362 363
}

364 365 366 367 368 369
/**
 * release_open_intent - free up open intent resources
 * @nd: pointer to nameidata
 */
void release_open_intent(struct nameidata *nd)
{
370
	if (nd->intent.open.file->f_path.dentry == NULL)
371 372 373 374 375
		put_filp(nd->intent.open.file);
	else
		fput(nd->intent.open.file);
}

376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399
static inline struct dentry *
do_revalidate(struct dentry *dentry, struct nameidata *nd)
{
	int status = dentry->d_op->d_revalidate(dentry, nd);
	if (unlikely(status <= 0)) {
		/*
		 * The dentry failed validation.
		 * If d_revalidate returned 0 attempt to invalidate
		 * the dentry otherwise d_revalidate is asking us
		 * to return a fail status.
		 */
		if (!status) {
			if (!d_invalidate(dentry)) {
				dput(dentry);
				dentry = NULL;
			}
		} else {
			dput(dentry);
			dentry = ERR_PTR(status);
		}
	}
	return dentry;
}

L
Linus Torvalds 已提交
400 401 402 403 404 405 406 407 408 409 410 411 412 413
/*
 * Internal lookup() using the new generic dcache.
 * SMP-safe
 */
static struct dentry * cached_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd)
{
	struct dentry * dentry = __d_lookup(parent, name);

	/* lockess __d_lookup may fail due to concurrent d_move() 
	 * in some unrelated directory, so try with d_lookup
	 */
	if (!dentry)
		dentry = d_lookup(parent, name);

414 415 416
	if (dentry && dentry->d_op && dentry->d_op->d_revalidate)
		dentry = do_revalidate(dentry, nd);

L
Linus Torvalds 已提交
417 418 419 420 421 422 423 424 425 426 427 428 429
	return dentry;
}

/*
 * Short-cut version of permission(), for calling by
 * path_walk(), when dcache lock is held.  Combines parts
 * of permission() and generic_permission(), and tests ONLY for
 * MAY_EXEC permission.
 *
 * If appropriate, check DAC only.  If not appropriate, or
 * short-cut DAC fails, then call permission() to do more
 * complete permission check.
 */
430
static int exec_permission_lite(struct inode *inode,
L
Linus Torvalds 已提交
431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472
				       struct nameidata *nd)
{
	umode_t	mode = inode->i_mode;

	if (inode->i_op && inode->i_op->permission)
		return -EAGAIN;

	if (current->fsuid == inode->i_uid)
		mode >>= 6;
	else if (in_group_p(inode->i_gid))
		mode >>= 3;

	if (mode & MAY_EXEC)
		goto ok;

	if ((inode->i_mode & S_IXUGO) && capable(CAP_DAC_OVERRIDE))
		goto ok;

	if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_OVERRIDE))
		goto ok;

	if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_READ_SEARCH))
		goto ok;

	return -EACCES;
ok:
	return security_inode_permission(inode, MAY_EXEC, nd);
}

/*
 * This is called when everything else fails, and we actually have
 * to go to the low-level filesystem to find out what we should do..
 *
 * We get the directory semaphore, and after getting that we also
 * make sure that nobody added the entry to the dcache in the meantime..
 * SMP-safe
 */
static struct dentry * real_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd)
{
	struct dentry * result;
	struct inode *dir = parent->d_inode;

473
	mutex_lock(&dir->i_mutex);
L
Linus Torvalds 已提交
474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498
	/*
	 * First re-do the cached lookup just in case it was created
	 * while we waited for the directory semaphore..
	 *
	 * FIXME! This could use version numbering or similar to
	 * avoid unnecessary cache lookups.
	 *
	 * The "dcache_lock" is purely to protect the RCU list walker
	 * from concurrent renames at this point (we mustn't get false
	 * negatives from the RCU list walk here, unlike the optimistic
	 * fast walk).
	 *
	 * so doing d_lookup() (with seqlock), instead of lockfree __d_lookup
	 */
	result = d_lookup(parent, name);
	if (!result) {
		struct dentry * dentry = d_alloc(parent, name);
		result = ERR_PTR(-ENOMEM);
		if (dentry) {
			result = dir->i_op->lookup(dir, dentry, nd);
			if (result)
				dput(dentry);
			else
				result = dentry;
		}
499
		mutex_unlock(&dir->i_mutex);
L
Linus Torvalds 已提交
500 501 502 503 504 505 506
		return result;
	}

	/*
	 * Uhhuh! Nasty case: the cache was re-populated while
	 * we waited on the semaphore. Need to revalidate.
	 */
507
	mutex_unlock(&dir->i_mutex);
L
Linus Torvalds 已提交
508
	if (result->d_op && result->d_op->d_revalidate) {
509 510
		result = do_revalidate(result, nd);
		if (!result)
L
Linus Torvalds 已提交
511 512 513 514 515 516 517 518
			result = ERR_PTR(-ENOENT);
	}
	return result;
}

static int __emul_lookup_dentry(const char *, struct nameidata *);

/* SMP-safe */
519
static __always_inline int
L
Linus Torvalds 已提交
520 521
walk_init_root(const char *name, struct nameidata *nd)
{
522 523 524 525 526 527 528
	struct fs_struct *fs = current->fs;

	read_lock(&fs->lock);
	if (fs->altroot && !(nd->flags & LOOKUP_NOALT)) {
		nd->mnt = mntget(fs->altrootmnt);
		nd->dentry = dget(fs->altroot);
		read_unlock(&fs->lock);
L
Linus Torvalds 已提交
529 530
		if (__emul_lookup_dentry(name,nd))
			return 0;
531
		read_lock(&fs->lock);
L
Linus Torvalds 已提交
532
	}
533 534 535
	nd->mnt = mntget(fs->rootmnt);
	nd->dentry = dget(fs->root);
	read_unlock(&fs->lock);
L
Linus Torvalds 已提交
536 537 538
	return 1;
}

539
static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link)
L
Linus Torvalds 已提交
540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573
{
	int res = 0;
	char *name;
	if (IS_ERR(link))
		goto fail;

	if (*link == '/') {
		path_release(nd);
		if (!walk_init_root(link, nd))
			/* weird __emul_prefix() stuff did it */
			goto out;
	}
	res = link_path_walk(link, nd);
out:
	if (nd->depth || res || nd->last_type!=LAST_NORM)
		return res;
	/*
	 * If it is an iterative symlinks resolution in open_namei() we
	 * have to copy the last component. And all that crap because of
	 * bloody create() on broken symlinks. Furrfu...
	 */
	name = __getname();
	if (unlikely(!name)) {
		path_release(nd);
		return -ENOMEM;
	}
	strcpy(name, nd->last.name);
	nd->last.name = name;
	return 0;
fail:
	path_release(nd);
	return PTR_ERR(link);
}

574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589
static inline void dput_path(struct path *path, struct nameidata *nd)
{
	dput(path->dentry);
	if (path->mnt != nd->mnt)
		mntput(path->mnt);
}

static inline void path_to_nameidata(struct path *path, struct nameidata *nd)
{
	dput(nd->dentry);
	if (nd->mnt != path->mnt)
		mntput(nd->mnt);
	nd->mnt = path->mnt;
	nd->dentry = path->dentry;
}

590
static __always_inline int __do_follow_link(struct path *path, struct nameidata *nd)
L
Linus Torvalds 已提交
591 592
{
	int error;
593
	void *cookie;
A
Al Viro 已提交
594
	struct dentry *dentry = path->dentry;
L
Linus Torvalds 已提交
595

A
Al Viro 已提交
596
	touch_atime(path->mnt, dentry);
L
Linus Torvalds 已提交
597
	nd_set_link(nd, NULL);
A
Al Viro 已提交
598

599 600 601 602 603
	if (path->mnt != nd->mnt) {
		path_to_nameidata(path, nd);
		dget(dentry);
	}
	mntget(path->mnt);
604 605 606
	cookie = dentry->d_inode->i_op->follow_link(dentry, nd);
	error = PTR_ERR(cookie);
	if (!IS_ERR(cookie)) {
L
Linus Torvalds 已提交
607
		char *s = nd_get_link(nd);
608
		error = 0;
L
Linus Torvalds 已提交
609 610 611
		if (s)
			error = __vfs_follow_link(nd, s);
		if (dentry->d_inode->i_op->put_link)
612
			dentry->d_inode->i_op->put_link(dentry, nd, cookie);
L
Linus Torvalds 已提交
613
	}
A
Al Viro 已提交
614 615
	dput(dentry);
	mntput(path->mnt);
L
Linus Torvalds 已提交
616 617 618 619 620 621 622 623 624 625 626

	return error;
}

/*
 * This limits recursive symlink follows to 8, while
 * limiting consecutive symlinks to 40.
 *
 * Without that kind of total limit, nasty chains of consecutive
 * symlinks can cause almost arbitrarily long lookups. 
 */
A
Al Viro 已提交
627
static inline int do_follow_link(struct path *path, struct nameidata *nd)
L
Linus Torvalds 已提交
628 629 630 631 632 633 634 635
{
	int err = -ELOOP;
	if (current->link_count >= MAX_NESTED_LINKS)
		goto loop;
	if (current->total_link_count >= 40)
		goto loop;
	BUG_ON(nd->depth >= MAX_NESTED_LINKS);
	cond_resched();
A
Al Viro 已提交
636
	err = security_inode_follow_link(path->dentry, nd);
L
Linus Torvalds 已提交
637 638 639 640 641
	if (err)
		goto loop;
	current->link_count++;
	current->total_link_count++;
	nd->depth++;
A
Al Viro 已提交
642
	err = __do_follow_link(path, nd);
A
Al Viro 已提交
643 644
	current->link_count--;
	nd->depth--;
L
Linus Torvalds 已提交
645 646
	return err;
loop:
M
Miklos Szeredi 已提交
647
	dput_path(path, nd);
A
Al Viro 已提交
648
	path_release(nd);
L
Linus Torvalds 已提交
649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674
	return err;
}

int follow_up(struct vfsmount **mnt, struct dentry **dentry)
{
	struct vfsmount *parent;
	struct dentry *mountpoint;
	spin_lock(&vfsmount_lock);
	parent=(*mnt)->mnt_parent;
	if (parent == *mnt) {
		spin_unlock(&vfsmount_lock);
		return 0;
	}
	mntget(parent);
	mountpoint=dget((*mnt)->mnt_mountpoint);
	spin_unlock(&vfsmount_lock);
	dput(*dentry);
	*dentry = mountpoint;
	mntput(*mnt);
	*mnt = parent;
	return 1;
}

/* no need for dcache_lock, as serialization is taken care in
 * namespace.c
 */
A
Al Viro 已提交
675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691
static int __follow_mount(struct path *path)
{
	int res = 0;
	while (d_mountpoint(path->dentry)) {
		struct vfsmount *mounted = lookup_mnt(path->mnt, path->dentry);
		if (!mounted)
			break;
		dput(path->dentry);
		if (res)
			mntput(path->mnt);
		path->mnt = mounted;
		path->dentry = dget(mounted->mnt_root);
		res = 1;
	}
	return res;
}

A
Al Viro 已提交
692
static void follow_mount(struct vfsmount **mnt, struct dentry **dentry)
L
Linus Torvalds 已提交
693 694 695 696 697
{
	while (d_mountpoint(*dentry)) {
		struct vfsmount *mounted = lookup_mnt(*mnt, *dentry);
		if (!mounted)
			break;
A
Al Viro 已提交
698
		dput(*dentry);
L
Linus Torvalds 已提交
699 700 701 702 703 704 705 706 707
		mntput(*mnt);
		*mnt = mounted;
		*dentry = dget(mounted->mnt_root);
	}
}

/* no need for dcache_lock, as serialization is taken care in
 * namespace.c
 */
A
Al Viro 已提交
708
int follow_down(struct vfsmount **mnt, struct dentry **dentry)
L
Linus Torvalds 已提交
709 710 711 712 713
{
	struct vfsmount *mounted;

	mounted = lookup_mnt(*mnt, *dentry);
	if (mounted) {
A
Al Viro 已提交
714
		dput(*dentry);
L
Linus Torvalds 已提交
715 716 717 718 719 720 721 722
		mntput(*mnt);
		*mnt = mounted;
		*dentry = dget(mounted->mnt_root);
		return 1;
	}
	return 0;
}

723
static __always_inline void follow_dotdot(struct nameidata *nd)
L
Linus Torvalds 已提交
724
{
725 726
	struct fs_struct *fs = current->fs;

L
Linus Torvalds 已提交
727 728
	while(1) {
		struct vfsmount *parent;
A
Al Viro 已提交
729
		struct dentry *old = nd->dentry;
L
Linus Torvalds 已提交
730

731 732 733 734
                read_lock(&fs->lock);
		if (nd->dentry == fs->root &&
		    nd->mnt == fs->rootmnt) {
                        read_unlock(&fs->lock);
L
Linus Torvalds 已提交
735 736
			break;
		}
737
                read_unlock(&fs->lock);
L
Linus Torvalds 已提交
738
		spin_lock(&dcache_lock);
A
Al Viro 已提交
739 740
		if (nd->dentry != nd->mnt->mnt_root) {
			nd->dentry = dget(nd->dentry->d_parent);
L
Linus Torvalds 已提交
741 742 743 744 745 746
			spin_unlock(&dcache_lock);
			dput(old);
			break;
		}
		spin_unlock(&dcache_lock);
		spin_lock(&vfsmount_lock);
A
Al Viro 已提交
747 748
		parent = nd->mnt->mnt_parent;
		if (parent == nd->mnt) {
L
Linus Torvalds 已提交
749 750 751 752
			spin_unlock(&vfsmount_lock);
			break;
		}
		mntget(parent);
A
Al Viro 已提交
753
		nd->dentry = dget(nd->mnt->mnt_mountpoint);
L
Linus Torvalds 已提交
754 755
		spin_unlock(&vfsmount_lock);
		dput(old);
A
Al Viro 已提交
756 757
		mntput(nd->mnt);
		nd->mnt = parent;
L
Linus Torvalds 已提交
758
	}
A
Al Viro 已提交
759
	follow_mount(&nd->mnt, &nd->dentry);
L
Linus Torvalds 已提交
760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779
}

/*
 *  It's more convoluted than I'd like it to be, but... it's still fairly
 *  small and for now I'd prefer to have fast path as straight as possible.
 *  It _is_ time-critical.
 */
static int do_lookup(struct nameidata *nd, struct qstr *name,
		     struct path *path)
{
	struct vfsmount *mnt = nd->mnt;
	struct dentry *dentry = __d_lookup(nd->dentry, name);

	if (!dentry)
		goto need_lookup;
	if (dentry->d_op && dentry->d_op->d_revalidate)
		goto need_revalidate;
done:
	path->mnt = mnt;
	path->dentry = dentry;
A
Al Viro 已提交
780
	__follow_mount(path);
L
Linus Torvalds 已提交
781 782 783 784 785 786 787 788 789
	return 0;

need_lookup:
	dentry = real_lookup(nd->dentry, name, nd);
	if (IS_ERR(dentry))
		goto fail;
	goto done;

need_revalidate:
790 791 792 793 794 795
	dentry = do_revalidate(dentry, nd);
	if (!dentry)
		goto need_lookup;
	if (IS_ERR(dentry))
		goto fail;
	goto done;
L
Linus Torvalds 已提交
796 797 798 799 800 801 802

fail:
	return PTR_ERR(dentry);
}

/*
 * Name resolution.
803 804
 * This is the basic name resolution function, turning a pathname into
 * the final dentry. We expect 'base' to be positive and a directory.
L
Linus Torvalds 已提交
805
 *
806 807
 * Returns 0 and nd will have valid dentry and mnt on success.
 * Returns error and drops reference to input namei data on failure.
L
Linus Torvalds 已提交
808 809 810 811 812 813 814 815 816 817 818 819 820 821 822
 */
static fastcall int __link_path_walk(const char * name, struct nameidata *nd)
{
	struct path next;
	struct inode *inode;
	int err;
	unsigned int lookup_flags = nd->flags;
	
	while (*name=='/')
		name++;
	if (!*name)
		goto return_reval;

	inode = nd->dentry->d_inode;
	if (nd->depth)
823
		lookup_flags = LOOKUP_FOLLOW | (nd->flags & LOOKUP_CONTINUE);
L
Linus Torvalds 已提交
824 825 826 827 828 829 830

	/* At this point we know we have a real path component. */
	for(;;) {
		unsigned long hash;
		struct qstr this;
		unsigned int c;

831
		nd->flags |= LOOKUP_CONTINUE;
L
Linus Torvalds 已提交
832
		err = exec_permission_lite(inode, nd);
833 834
		if (err == -EAGAIN)
			err = vfs_permission(nd, MAY_EXEC);
L
Linus Torvalds 已提交
835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867
 		if (err)
			break;

		this.name = name;
		c = *(const unsigned char *)name;

		hash = init_name_hash();
		do {
			name++;
			hash = partial_name_hash(c, hash);
			c = *(const unsigned char *)name;
		} while (c && (c != '/'));
		this.len = name - (const char *) this.name;
		this.hash = end_name_hash(hash);

		/* remove trailing slashes? */
		if (!c)
			goto last_component;
		while (*++name == '/');
		if (!*name)
			goto last_with_slashes;

		/*
		 * "." and ".." are special - ".." especially so because it has
		 * to be able to know about the current root directory and
		 * parent relationships.
		 */
		if (this.name[0] == '.') switch (this.len) {
			default:
				break;
			case 2:	
				if (this.name[1] != '.')
					break;
A
Al Viro 已提交
868
				follow_dotdot(nd);
L
Linus Torvalds 已提交
869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896
				inode = nd->dentry->d_inode;
				/* fallthrough */
			case 1:
				continue;
		}
		/*
		 * See if the low-level filesystem might want
		 * to use its own hash..
		 */
		if (nd->dentry->d_op && nd->dentry->d_op->d_hash) {
			err = nd->dentry->d_op->d_hash(nd->dentry, &this);
			if (err < 0)
				break;
		}
		/* This does the actual lookups.. */
		err = do_lookup(nd, &this, &next);
		if (err)
			break;

		err = -ENOENT;
		inode = next.dentry->d_inode;
		if (!inode)
			goto out_dput;
		err = -ENOTDIR; 
		if (!inode->i_op)
			goto out_dput;

		if (inode->i_op->follow_link) {
A
Al Viro 已提交
897
			err = do_follow_link(&next, nd);
L
Linus Torvalds 已提交
898 899 900 901 902 903 904 905 906
			if (err)
				goto return_err;
			err = -ENOENT;
			inode = nd->dentry->d_inode;
			if (!inode)
				break;
			err = -ENOTDIR; 
			if (!inode->i_op)
				break;
M
Miklos Szeredi 已提交
907 908
		} else
			path_to_nameidata(&next, nd);
L
Linus Torvalds 已提交
909 910 911 912 913 914 915 916 917
		err = -ENOTDIR; 
		if (!inode->i_op->lookup)
			break;
		continue;
		/* here ends the main loop */

last_with_slashes:
		lookup_flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
last_component:
918 919
		/* Clear LOOKUP_CONTINUE iff it was previously unset */
		nd->flags &= lookup_flags | ~LOOKUP_CONTINUE;
L
Linus Torvalds 已提交
920 921 922 923 924 925 926 927
		if (lookup_flags & LOOKUP_PARENT)
			goto lookup_parent;
		if (this.name[0] == '.') switch (this.len) {
			default:
				break;
			case 2:	
				if (this.name[1] != '.')
					break;
A
Al Viro 已提交
928
				follow_dotdot(nd);
L
Linus Torvalds 已提交
929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944
				inode = nd->dentry->d_inode;
				/* fallthrough */
			case 1:
				goto return_reval;
		}
		if (nd->dentry->d_op && nd->dentry->d_op->d_hash) {
			err = nd->dentry->d_op->d_hash(nd->dentry, &this);
			if (err < 0)
				break;
		}
		err = do_lookup(nd, &this, &next);
		if (err)
			break;
		inode = next.dentry->d_inode;
		if ((lookup_flags & LOOKUP_FOLLOW)
		    && inode && inode->i_op && inode->i_op->follow_link) {
A
Al Viro 已提交
945
			err = do_follow_link(&next, nd);
L
Linus Torvalds 已提交
946 947 948
			if (err)
				goto return_err;
			inode = nd->dentry->d_inode;
M
Miklos Szeredi 已提交
949 950
		} else
			path_to_nameidata(&next, nd);
L
Linus Torvalds 已提交
951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985
		err = -ENOENT;
		if (!inode)
			break;
		if (lookup_flags & LOOKUP_DIRECTORY) {
			err = -ENOTDIR; 
			if (!inode->i_op || !inode->i_op->lookup)
				break;
		}
		goto return_base;
lookup_parent:
		nd->last = this;
		nd->last_type = LAST_NORM;
		if (this.name[0] != '.')
			goto return_base;
		if (this.len == 1)
			nd->last_type = LAST_DOT;
		else if (this.len == 2 && this.name[1] == '.')
			nd->last_type = LAST_DOTDOT;
		else
			goto return_base;
return_reval:
		/*
		 * We bypassed the ordinary revalidation routines.
		 * We may need to check the cached dentry for staleness.
		 */
		if (nd->dentry && nd->dentry->d_sb &&
		    (nd->dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)) {
			err = -ESTALE;
			/* Note: we do not d_invalidate() */
			if (!nd->dentry->d_op->d_revalidate(nd->dentry, nd))
				break;
		}
return_base:
		return 0;
out_dput:
M
Miklos Szeredi 已提交
986
		dput_path(&next, nd);
L
Linus Torvalds 已提交
987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030
		break;
	}
	path_release(nd);
return_err:
	return err;
}

/*
 * Wrapper to retry pathname resolution whenever the underlying
 * file system returns an ESTALE.
 *
 * Retry the whole path once, forcing real lookup requests
 * instead of relying on the dcache.
 */
int fastcall link_path_walk(const char *name, struct nameidata *nd)
{
	struct nameidata save = *nd;
	int result;

	/* make sure the stuff we saved doesn't go away */
	dget(save.dentry);
	mntget(save.mnt);

	result = __link_path_walk(name, nd);
	if (result == -ESTALE) {
		*nd = save;
		dget(nd->dentry);
		mntget(nd->mnt);
		nd->flags |= LOOKUP_REVAL;
		result = __link_path_walk(name, nd);
	}

	dput(save.dentry);
	mntput(save.mnt);

	return result;
}

int fastcall path_walk(const char * name, struct nameidata *nd)
{
	current->total_link_count = 0;
	return link_path_walk(name, nd);
}

1031 1032 1033 1034
/* 
 * SMP-safe: Returns 1 and nd will have valid dentry and mnt, if
 * everything is done. Returns 0 and drops input nd, if lookup failed;
 */
L
Linus Torvalds 已提交
1035 1036 1037 1038 1039 1040 1041 1042 1043 1044
static int __emul_lookup_dentry(const char *name, struct nameidata *nd)
{
	if (path_walk(name, nd))
		return 0;		/* something went wrong... */

	if (!nd->dentry->d_inode || S_ISDIR(nd->dentry->d_inode->i_mode)) {
		struct dentry *old_dentry = nd->dentry;
		struct vfsmount *old_mnt = nd->mnt;
		struct qstr last = nd->last;
		int last_type = nd->last_type;
1045 1046
		struct fs_struct *fs = current->fs;

L
Linus Torvalds 已提交
1047
		/*
1048 1049
		 * NAME was not found in alternate root or it's a directory.
		 * Try to find it in the normal root:
L
Linus Torvalds 已提交
1050 1051
		 */
		nd->last_type = LAST_ROOT;
1052 1053 1054 1055
		read_lock(&fs->lock);
		nd->mnt = mntget(fs->rootmnt);
		nd->dentry = dget(fs->root);
		read_unlock(&fs->lock);
L
Linus Torvalds 已提交
1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078
		if (path_walk(name, nd) == 0) {
			if (nd->dentry->d_inode) {
				dput(old_dentry);
				mntput(old_mnt);
				return 1;
			}
			path_release(nd);
		}
		nd->dentry = old_dentry;
		nd->mnt = old_mnt;
		nd->last = last;
		nd->last_type = last_type;
	}
	return 1;
}

void set_fs_altroot(void)
{
	char *emul = __emul_prefix();
	struct nameidata nd;
	struct vfsmount *mnt = NULL, *oldmnt;
	struct dentry *dentry = NULL, *olddentry;
	int err;
1079
	struct fs_struct *fs = current->fs;
L
Linus Torvalds 已提交
1080 1081 1082 1083 1084 1085 1086 1087 1088

	if (!emul)
		goto set_it;
	err = path_lookup(emul, LOOKUP_FOLLOW|LOOKUP_DIRECTORY|LOOKUP_NOALT, &nd);
	if (!err) {
		mnt = nd.mnt;
		dentry = nd.dentry;
	}
set_it:
1089 1090 1091 1092 1093 1094
	write_lock(&fs->lock);
	oldmnt = fs->altrootmnt;
	olddentry = fs->altroot;
	fs->altrootmnt = mnt;
	fs->altroot = dentry;
	write_unlock(&fs->lock);
L
Linus Torvalds 已提交
1095 1096 1097 1098 1099 1100
	if (olddentry) {
		dput(olddentry);
		mntput(oldmnt);
	}
}

1101
/* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
1102 1103
static int fastcall do_path_lookup(int dfd, const char *name,
				unsigned int flags, struct nameidata *nd)
L
Linus Torvalds 已提交
1104
{
1105
	int retval = 0;
1106 1107
	int fput_needed;
	struct file *file;
1108
	struct fs_struct *fs = current->fs;
L
Linus Torvalds 已提交
1109 1110 1111 1112 1113 1114

	nd->last_type = LAST_ROOT; /* if there are only slashes... */
	nd->flags = flags;
	nd->depth = 0;

	if (*name=='/') {
1115 1116 1117 1118 1119
		read_lock(&fs->lock);
		if (fs->altroot && !(nd->flags & LOOKUP_NOALT)) {
			nd->mnt = mntget(fs->altrootmnt);
			nd->dentry = dget(fs->altroot);
			read_unlock(&fs->lock);
L
Linus Torvalds 已提交
1120
			if (__emul_lookup_dentry(name,nd))
1121
				goto out; /* found in altroot */
1122
			read_lock(&fs->lock);
L
Linus Torvalds 已提交
1123
		}
1124 1125 1126
		nd->mnt = mntget(fs->rootmnt);
		nd->dentry = dget(fs->root);
		read_unlock(&fs->lock);
1127
	} else if (dfd == AT_FDCWD) {
1128 1129 1130 1131
		read_lock(&fs->lock);
		nd->mnt = mntget(fs->pwdmnt);
		nd->dentry = dget(fs->pwd);
		read_unlock(&fs->lock);
1132 1133 1134 1135
	} else {
		struct dentry *dentry;

		file = fget_light(dfd, &fput_needed);
1136 1137
		retval = -EBADF;
		if (!file)
1138
			goto out_fail;
1139

1140
		dentry = file->f_path.dentry;
1141

1142 1143
		retval = -ENOTDIR;
		if (!S_ISDIR(dentry->d_inode->i_mode))
1144
			goto fput_fail;
1145 1146

		retval = file_permission(file, MAY_EXEC);
1147
		if (retval)
1148
			goto fput_fail;
1149

1150
		nd->mnt = mntget(file->f_path.mnt);
1151 1152 1153
		nd->dentry = dget(dentry);

		fput_light(file, fput_needed);
L
Linus Torvalds 已提交
1154
	}
1155 1156

	retval = path_walk(name, nd);
1157
out:
1158
	if (unlikely(!retval && !audit_dummy_context() && nd->dentry &&
1159
				nd->dentry->d_inode))
1160
		audit_inode(name, nd->dentry->d_inode);
1161
out_fail:
1162 1163
	return retval;

1164
fput_fail:
1165
	fput_light(file, fput_needed);
1166
	goto out_fail;
L
Linus Torvalds 已提交
1167 1168
}

1169 1170 1171 1172 1173 1174
int fastcall path_lookup(const char *name, unsigned int flags,
			struct nameidata *nd)
{
	return do_path_lookup(AT_FDCWD, name, flags, nd);
}

1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205
/**
 * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair
 * @dentry:  pointer to dentry of the base directory
 * @mnt: pointer to vfs mount of the base directory
 * @name: pointer to file name
 * @flags: lookup flags
 * @nd: pointer to nameidata
 */
int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt,
		    const char *name, unsigned int flags,
		    struct nameidata *nd)
{
	int retval;

	/* same as do_path_lookup */
	nd->last_type = LAST_ROOT;
	nd->flags = flags;
	nd->depth = 0;

	nd->mnt = mntget(mnt);
	nd->dentry = dget(dentry);

	retval = path_walk(name, nd);
	if (unlikely(!retval && !audit_dummy_context() && nd->dentry &&
				nd->dentry->d_inode))
		audit_inode(name, nd->dentry->d_inode);

	return retval;

}

1206 1207 1208
static int __path_lookup_intent_open(int dfd, const char *name,
		unsigned int lookup_flags, struct nameidata *nd,
		int open_flags, int create_mode)
1209 1210 1211 1212 1213 1214 1215 1216 1217
{
	struct file *filp = get_empty_filp();
	int err;

	if (filp == NULL)
		return -ENFILE;
	nd->intent.open.file = filp;
	nd->intent.open.flags = open_flags;
	nd->intent.open.create_mode = create_mode;
1218
	err = do_path_lookup(dfd, name, lookup_flags|LOOKUP_OPEN, nd);
1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230
	if (IS_ERR(nd->intent.open.file)) {
		if (err == 0) {
			err = PTR_ERR(nd->intent.open.file);
			path_release(nd);
		}
	} else if (err != 0)
		release_open_intent(nd);
	return err;
}

/**
 * path_lookup_open - lookup a file path with open intent
1231
 * @dfd: the directory to use as base, or AT_FDCWD
1232 1233 1234 1235 1236
 * @name: pointer to file name
 * @lookup_flags: lookup intent flags
 * @nd: pointer to nameidata
 * @open_flags: open intent flags
 */
1237
int path_lookup_open(int dfd, const char *name, unsigned int lookup_flags,
1238 1239
		struct nameidata *nd, int open_flags)
{
1240
	return __path_lookup_intent_open(dfd, name, lookup_flags, nd,
1241 1242 1243 1244 1245
			open_flags, 0);
}

/**
 * path_lookup_create - lookup a file path with open + create intent
1246
 * @dfd: the directory to use as base, or AT_FDCWD
1247 1248 1249 1250 1251 1252
 * @name: pointer to file name
 * @lookup_flags: lookup intent flags
 * @nd: pointer to nameidata
 * @open_flags: open intent flags
 * @create_mode: create intent flags
 */
1253 1254 1255
static int path_lookup_create(int dfd, const char *name,
			      unsigned int lookup_flags, struct nameidata *nd,
			      int open_flags, int create_mode)
1256
{
1257 1258
	return __path_lookup_intent_open(dfd, name, lookup_flags|LOOKUP_CREATE,
			nd, open_flags, create_mode);
1259 1260 1261 1262 1263 1264 1265 1266 1267
}

int __user_path_lookup_open(const char __user *name, unsigned int lookup_flags,
		struct nameidata *nd, int open_flags)
{
	char *tmp = getname(name);
	int err = PTR_ERR(tmp);

	if (!IS_ERR(tmp)) {
1268
		err = __path_lookup_intent_open(AT_FDCWD, tmp, lookup_flags, nd, open_flags, 0);
1269 1270 1271 1272 1273
		putname(tmp);
	}
	return err;
}

1274
static inline struct dentry *__lookup_hash_kern(struct qstr *name, struct dentry *base, struct nameidata *nd)
L
Linus Torvalds 已提交
1275
{
1276
	struct dentry *dentry;
L
Linus Torvalds 已提交
1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308
	struct inode *inode;
	int err;

	inode = base->d_inode;

	/*
	 * See if the low-level filesystem might want
	 * to use its own hash..
	 */
	if (base->d_op && base->d_op->d_hash) {
		err = base->d_op->d_hash(base, name);
		dentry = ERR_PTR(err);
		if (err < 0)
			goto out;
	}

	dentry = cached_lookup(base, name, nd);
	if (!dentry) {
		struct dentry *new = d_alloc(base, name);
		dentry = ERR_PTR(-ENOMEM);
		if (!new)
			goto out;
		dentry = inode->i_op->lookup(inode, new, nd);
		if (!dentry)
			dentry = new;
		else
			dput(new);
	}
out:
	return dentry;
}

1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331
/*
 * Restricted form of lookup. Doesn't follow links, single-component only,
 * needs parent already locked. Doesn't follow mounts.
 * SMP-safe.
 */
static inline struct dentry * __lookup_hash(struct qstr *name, struct dentry *base, struct nameidata *nd)
{
	struct dentry *dentry;
	struct inode *inode;
	int err;

	inode = base->d_inode;

	err = permission(inode, MAY_EXEC, nd);
	dentry = ERR_PTR(err);
	if (err)
		goto out;

	dentry = __lookup_hash_kern(name, base, nd);
out:
	return dentry;
}

1332
static struct dentry *lookup_hash(struct nameidata *nd)
L
Linus Torvalds 已提交
1333
{
1334
	return __lookup_hash(&nd->last, nd->dentry, nd);
L
Linus Torvalds 已提交
1335 1336 1337
}

/* SMP-safe */
1338
static inline int __lookup_one_len(const char *name, struct qstr *this, struct dentry *base, int len)
L
Linus Torvalds 已提交
1339 1340 1341 1342
{
	unsigned long hash;
	unsigned int c;

1343 1344
	this->name = name;
	this->len = len;
L
Linus Torvalds 已提交
1345
	if (!len)
1346
		return -EACCES;
L
Linus Torvalds 已提交
1347 1348 1349 1350 1351

	hash = init_name_hash();
	while (len--) {
		c = *(const unsigned char *)name++;
		if (c == '/' || c == '\0')
1352
			return -EACCES;
L
Linus Torvalds 已提交
1353 1354
		hash = partial_name_hash(c, hash);
	}
1355 1356 1357
	this->hash = end_name_hash(hash);
	return 0;
}
L
Linus Torvalds 已提交
1358

1359 1360 1361 1362 1363 1364 1365 1366
struct dentry *lookup_one_len(const char *name, struct dentry *base, int len)
{
	int err;
	struct qstr this;

	err = __lookup_one_len(name, &this, base, len);
	if (err)
		return ERR_PTR(err);
1367
	return __lookup_hash(&this, base, NULL);
1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378
}

struct dentry *lookup_one_len_kern(const char *name, struct dentry *base, int len)
{
	int err;
	struct qstr this;

	err = __lookup_one_len(name, &this, base, len);
	if (err)
		return ERR_PTR(err);
	return __lookup_hash_kern(&this, base, NULL);
L
Linus Torvalds 已提交
1379 1380
}

1381 1382
int fastcall __user_walk_fd(int dfd, const char __user *name, unsigned flags,
			    struct nameidata *nd)
L
Linus Torvalds 已提交
1383 1384 1385 1386 1387
{
	char *tmp = getname(name);
	int err = PTR_ERR(tmp);

	if (!IS_ERR(tmp)) {
1388
		err = do_path_lookup(dfd, tmp, flags, nd);
L
Linus Torvalds 已提交
1389 1390 1391 1392 1393
		putname(tmp);
	}
	return err;
}

1394 1395 1396 1397 1398
int fastcall __user_walk(const char __user *name, unsigned flags, struct nameidata *nd)
{
	return __user_walk_fd(AT_FDCWD, name, flags, nd);
}

L
Linus Torvalds 已提交
1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432
/*
 * It's inline, so penalty for filesystems that don't use sticky bit is
 * minimal.
 */
static inline int check_sticky(struct inode *dir, struct inode *inode)
{
	if (!(dir->i_mode & S_ISVTX))
		return 0;
	if (inode->i_uid == current->fsuid)
		return 0;
	if (dir->i_uid == current->fsuid)
		return 0;
	return !capable(CAP_FOWNER);
}

/*
 *	Check whether we can remove a link victim from directory dir, check
 *  whether the type of victim is right.
 *  1. We can't do it if dir is read-only (done in permission())
 *  2. We should have write and exec permissions on dir
 *  3. We can't remove anything from append-only dir
 *  4. We can't do anything with immutable dir (done in permission())
 *  5. If the sticky bit on dir is set we should either
 *	a. be owner of dir, or
 *	b. be owner of victim, or
 *	c. have CAP_FOWNER capability
 *  6. If the victim is append-only or immutable we can't do antyhing with
 *     links pointing to it.
 *  7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
 *  8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
 *  9. We can't remove a root or mountpoint.
 * 10. We don't allow removal of NFS sillyrenamed files; it's handled by
 *     nfs_async_unlink().
 */
1433
static int may_delete(struct inode *dir,struct dentry *victim,int isdir)
L
Linus Torvalds 已提交
1434 1435 1436 1437 1438 1439 1440
{
	int error;

	if (!victim->d_inode)
		return -ENOENT;

	BUG_ON(victim->d_parent->d_inode != dir);
1441
	audit_inode_child(victim->d_name.name, victim->d_inode, dir);
L
Linus Torvalds 已提交
1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506

	error = permission(dir,MAY_WRITE | MAY_EXEC, NULL);
	if (error)
		return error;
	if (IS_APPEND(dir))
		return -EPERM;
	if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)||
	    IS_IMMUTABLE(victim->d_inode))
		return -EPERM;
	if (isdir) {
		if (!S_ISDIR(victim->d_inode->i_mode))
			return -ENOTDIR;
		if (IS_ROOT(victim))
			return -EBUSY;
	} else if (S_ISDIR(victim->d_inode->i_mode))
		return -EISDIR;
	if (IS_DEADDIR(dir))
		return -ENOENT;
	if (victim->d_flags & DCACHE_NFSFS_RENAMED)
		return -EBUSY;
	return 0;
}

/*	Check whether we can create an object with dentry child in directory
 *  dir.
 *  1. We can't do it if child already exists (open has special treatment for
 *     this case, but since we are inlined it's OK)
 *  2. We can't do it if dir is read-only (done in permission())
 *  3. We should have write and exec permissions on dir
 *  4. We can't do it if dir is immutable (done in permission())
 */
static inline int may_create(struct inode *dir, struct dentry *child,
			     struct nameidata *nd)
{
	if (child->d_inode)
		return -EEXIST;
	if (IS_DEADDIR(dir))
		return -ENOENT;
	return permission(dir,MAY_WRITE | MAY_EXEC, nd);
}

/* 
 * O_DIRECTORY translates into forcing a directory lookup.
 */
static inline int lookup_flags(unsigned int f)
{
	unsigned long retval = LOOKUP_FOLLOW;

	if (f & O_NOFOLLOW)
		retval &= ~LOOKUP_FOLLOW;
	
	if (f & O_DIRECTORY)
		retval |= LOOKUP_DIRECTORY;

	return retval;
}

/*
 * p1 and p2 should be directories on the same fs.
 */
struct dentry *lock_rename(struct dentry *p1, struct dentry *p2)
{
	struct dentry *p;

	if (p1 == p2) {
I
Ingo Molnar 已提交
1507
		mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
L
Linus Torvalds 已提交
1508 1509 1510
		return NULL;
	}

1511
	mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex);
L
Linus Torvalds 已提交
1512 1513 1514

	for (p = p1; p->d_parent != p; p = p->d_parent) {
		if (p->d_parent == p2) {
I
Ingo Molnar 已提交
1515 1516
			mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT);
			mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD);
L
Linus Torvalds 已提交
1517 1518 1519 1520 1521 1522
			return p;
		}
	}

	for (p = p2; p->d_parent != p; p = p->d_parent) {
		if (p->d_parent == p1) {
I
Ingo Molnar 已提交
1523 1524
			mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
			mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD);
L
Linus Torvalds 已提交
1525 1526 1527 1528
			return p;
		}
	}

I
Ingo Molnar 已提交
1529 1530
	mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
	mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD);
L
Linus Torvalds 已提交
1531 1532 1533 1534 1535
	return NULL;
}

void unlock_rename(struct dentry *p1, struct dentry *p2)
{
1536
	mutex_unlock(&p1->d_inode->i_mutex);
L
Linus Torvalds 已提交
1537
	if (p1 != p2) {
1538
		mutex_unlock(&p2->d_inode->i_mutex);
1539
		mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex);
L
Linus Torvalds 已提交
1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559
	}
}

int vfs_create(struct inode *dir, struct dentry *dentry, int mode,
		struct nameidata *nd)
{
	int error = may_create(dir, dentry, nd);

	if (error)
		return error;

	if (!dir->i_op || !dir->i_op->create)
		return -EACCES;	/* shouldn't it be ENOSYS? */
	mode &= S_IALLUGO;
	mode |= S_IFREG;
	error = security_inode_create(dir, dentry, mode);
	if (error)
		return error;
	DQUOT_INIT(dir);
	error = dir->i_op->create(dir, dentry, mode, nd);
1560
	if (!error)
1561
		fsnotify_create(dir, dentry);
L
Linus Torvalds 已提交
1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579
	return error;
}

int may_open(struct nameidata *nd, int acc_mode, int flag)
{
	struct dentry *dentry = nd->dentry;
	struct inode *inode = dentry->d_inode;
	int error;

	if (!inode)
		return -ENOENT;

	if (S_ISLNK(inode->i_mode))
		return -ELOOP;
	
	if (S_ISDIR(inode->i_mode) && (flag & FMODE_WRITE))
		return -EISDIR;

1580
	error = vfs_permission(nd, acc_mode);
L
Linus Torvalds 已提交
1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609
	if (error)
		return error;

	/*
	 * FIFO's, sockets and device files are special: they don't
	 * actually live on the filesystem itself, and as such you
	 * can write to them even if the filesystem is read-only.
	 */
	if (S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
	    	flag &= ~O_TRUNC;
	} else if (S_ISBLK(inode->i_mode) || S_ISCHR(inode->i_mode)) {
		if (nd->mnt->mnt_flags & MNT_NODEV)
			return -EACCES;

		flag &= ~O_TRUNC;
	} else if (IS_RDONLY(inode) && (flag & FMODE_WRITE))
		return -EROFS;
	/*
	 * An append-only file must be opened in append mode for writing.
	 */
	if (IS_APPEND(inode)) {
		if  ((flag & FMODE_WRITE) && !(flag & O_APPEND))
			return -EPERM;
		if (flag & O_TRUNC)
			return -EPERM;
	}

	/* O_NOATIME can only be set by the owner or superuser */
	if (flag & O_NOATIME)
1610
		if (!is_owner_or_cap(inode))
L
Linus Torvalds 已提交
1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631
			return -EPERM;

	/*
	 * Ensure there are no outstanding leases on the file.
	 */
	error = break_lease(inode, flag);
	if (error)
		return error;

	if (flag & O_TRUNC) {
		error = get_write_access(inode);
		if (error)
			return error;

		/*
		 * Refuse to truncate files with mandatory locks held on them.
		 */
		error = locks_verify_locked(inode);
		if (!error) {
			DQUOT_INIT(inode);
			
1632
			error = do_truncate(dentry, 0, ATTR_MTIME|ATTR_CTIME, NULL);
L
Linus Torvalds 已提交
1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643
		}
		put_write_access(inode);
		if (error)
			return error;
	} else
		if (flag & FMODE_WRITE)
			DQUOT_INIT(inode);

	return 0;
}

1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661
static int open_namei_create(struct nameidata *nd, struct path *path,
				int flag, int mode)
{
	int error;
	struct dentry *dir = nd->dentry;

	if (!IS_POSIXACL(dir->d_inode))
		mode &= ~current->fs->umask;
	error = vfs_create(dir->d_inode, path->dentry, mode, nd);
	mutex_unlock(&dir->d_inode->i_mutex);
	dput(nd->dentry);
	nd->dentry = path->dentry;
	if (error)
		return error;
	/* Don't check for write permission, don't truncate */
	return may_open(nd, 0, flag & ~O_TRUNC);
}

L
Linus Torvalds 已提交
1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675
/*
 *	open_namei()
 *
 * namei for open - this is in fact almost the whole open-routine.
 *
 * Note that the low bits of "flag" aren't the same as in the open
 * system call - they are 00 - no permissions needed
 *			  01 - read permission needed
 *			  10 - write permission needed
 *			  11 - read/write permissions needed
 * which is a lot more logical, and also allows the "no perm" needed
 * for symlinks (where the permissions are checked later).
 * SMP-safe
 */
1676 1677
int open_namei(int dfd, const char *pathname, int flag,
		int mode, struct nameidata *nd)
L
Linus Torvalds 已提交
1678
{
1679
	int acc_mode, error;
A
Al Viro 已提交
1680
	struct path path;
L
Linus Torvalds 已提交
1681 1682 1683 1684 1685
	struct dentry *dir;
	int count = 0;

	acc_mode = ACC_MODE(flag);

1686 1687 1688 1689
	/* O_TRUNC implies we need access checks for write permissions */
	if (flag & O_TRUNC)
		acc_mode |= MAY_WRITE;

L
Linus Torvalds 已提交
1690 1691 1692 1693 1694 1695 1696 1697 1698
	/* Allow the LSM permission hook to distinguish append 
	   access from general write access. */
	if (flag & O_APPEND)
		acc_mode |= MAY_APPEND;

	/*
	 * The simplest case - just a plain lookup.
	 */
	if (!(flag & O_CREAT)) {
1699 1700
		error = path_lookup_open(dfd, pathname, lookup_flags(flag),
					 nd, flag);
L
Linus Torvalds 已提交
1701 1702 1703 1704 1705 1706 1707 1708
		if (error)
			return error;
		goto ok;
	}

	/*
	 * Create - we need to know the parent.
	 */
1709
	error = path_lookup_create(dfd,pathname,LOOKUP_PARENT,nd,flag,mode);
L
Linus Torvalds 已提交
1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723
	if (error)
		return error;

	/*
	 * We have the parent and last component. First of all, check
	 * that we are not asked to creat(2) an obvious directory - that
	 * will not do.
	 */
	error = -EISDIR;
	if (nd->last_type != LAST_NORM || nd->last.name[nd->last.len])
		goto exit;

	dir = nd->dentry;
	nd->flags &= ~LOOKUP_PARENT;
1724
	mutex_lock(&dir->d_inode->i_mutex);
1725
	path.dentry = lookup_hash(nd);
A
Al Viro 已提交
1726
	path.mnt = nd->mnt;
L
Linus Torvalds 已提交
1727 1728

do_last:
A
Al Viro 已提交
1729 1730
	error = PTR_ERR(path.dentry);
	if (IS_ERR(path.dentry)) {
1731
		mutex_unlock(&dir->d_inode->i_mutex);
L
Linus Torvalds 已提交
1732 1733 1734
		goto exit;
	}

1735 1736 1737 1738 1739 1740
	if (IS_ERR(nd->intent.open.file)) {
		mutex_unlock(&dir->d_inode->i_mutex);
		error = PTR_ERR(nd->intent.open.file);
		goto exit_dput;
	}

L
Linus Torvalds 已提交
1741
	/* Negative dentry, just create the file */
A
Al Viro 已提交
1742
	if (!path.dentry->d_inode) {
1743
		error = open_namei_create(nd, &path, flag, mode);
L
Linus Torvalds 已提交
1744 1745
		if (error)
			goto exit;
1746
		return 0;
L
Linus Torvalds 已提交
1747 1748 1749 1750 1751
	}

	/*
	 * It already exists.
	 */
1752
	mutex_unlock(&dir->d_inode->i_mutex);
1753
	audit_inode(pathname, path.dentry->d_inode);
L
Linus Torvalds 已提交
1754 1755 1756 1757 1758

	error = -EEXIST;
	if (flag & O_EXCL)
		goto exit_dput;

A
Al Viro 已提交
1759
	if (__follow_mount(&path)) {
L
Linus Torvalds 已提交
1760
		error = -ELOOP;
A
Al Viro 已提交
1761 1762
		if (flag & O_NOFOLLOW)
			goto exit_dput;
L
Linus Torvalds 已提交
1763
	}
1764

L
Linus Torvalds 已提交
1765
	error = -ENOENT;
A
Al Viro 已提交
1766
	if (!path.dentry->d_inode)
L
Linus Torvalds 已提交
1767
		goto exit_dput;
A
Al Viro 已提交
1768
	if (path.dentry->d_inode->i_op && path.dentry->d_inode->i_op->follow_link)
L
Linus Torvalds 已提交
1769 1770
		goto do_link;

M
Miklos Szeredi 已提交
1771
	path_to_nameidata(&path, nd);
L
Linus Torvalds 已提交
1772
	error = -EISDIR;
A
Al Viro 已提交
1773
	if (path.dentry->d_inode && S_ISDIR(path.dentry->d_inode->i_mode))
L
Linus Torvalds 已提交
1774 1775 1776 1777 1778 1779 1780 1781
		goto exit;
ok:
	error = may_open(nd, acc_mode, flag);
	if (error)
		goto exit;
	return 0;

exit_dput:
M
Miklos Szeredi 已提交
1782
	dput_path(&path, nd);
L
Linus Torvalds 已提交
1783
exit:
1784 1785
	if (!IS_ERR(nd->intent.open.file))
		release_open_intent(nd);
L
Linus Torvalds 已提交
1786 1787 1788 1789 1790 1791 1792 1793 1794 1795 1796 1797 1798 1799 1800 1801 1802 1803
	path_release(nd);
	return error;

do_link:
	error = -ELOOP;
	if (flag & O_NOFOLLOW)
		goto exit_dput;
	/*
	 * This is subtle. Instead of calling do_follow_link() we do the
	 * thing by hands. The reason is that this way we have zero link_count
	 * and path_walk() (called from ->follow_link) honoring LOOKUP_PARENT.
	 * After that we have the parent and last component, i.e.
	 * we are in the same situation as after the first path_walk().
	 * Well, almost - if the last component is normal we get its copy
	 * stored in nd->last.name and we will have to putname() it when we
	 * are done. Procfs-like symlinks just set LAST_BIND.
	 */
	nd->flags |= LOOKUP_PARENT;
A
Al Viro 已提交
1804
	error = security_inode_follow_link(path.dentry, nd);
L
Linus Torvalds 已提交
1805 1806
	if (error)
		goto exit_dput;
A
Al Viro 已提交
1807
	error = __do_follow_link(&path, nd);
K
Kirill Korotaev 已提交
1808 1809 1810 1811 1812 1813
	if (error) {
		/* Does someone understand code flow here? Or it is only
		 * me so stupid? Anathema to whoever designed this non-sense
		 * with "intent.open".
		 */
		release_open_intent(nd);
L
Linus Torvalds 已提交
1814
		return error;
K
Kirill Korotaev 已提交
1815
	}
L
Linus Torvalds 已提交
1816
	nd->flags &= ~LOOKUP_PARENT;
A
Al Viro 已提交
1817
	if (nd->last_type == LAST_BIND)
L
Linus Torvalds 已提交
1818 1819 1820 1821 1822
		goto ok;
	error = -EISDIR;
	if (nd->last_type != LAST_NORM)
		goto exit;
	if (nd->last.name[nd->last.len]) {
1823
		__putname(nd->last.name);
L
Linus Torvalds 已提交
1824 1825 1826 1827
		goto exit;
	}
	error = -ELOOP;
	if (count++==32) {
1828
		__putname(nd->last.name);
L
Linus Torvalds 已提交
1829 1830 1831
		goto exit;
	}
	dir = nd->dentry;
1832
	mutex_lock(&dir->d_inode->i_mutex);
1833
	path.dentry = lookup_hash(nd);
A
Al Viro 已提交
1834
	path.mnt = nd->mnt;
1835
	__putname(nd->last.name);
L
Linus Torvalds 已提交
1836 1837 1838 1839 1840 1841 1842 1843 1844 1845
	goto do_last;
}

/**
 * lookup_create - lookup a dentry, creating it if it doesn't exist
 * @nd: nameidata info
 * @is_dir: directory flag
 *
 * Simple function to lookup and return a dentry and create it
 * if it doesn't exist.  Is SMP-safe.
1846
 *
1847
 * Returns with nd->dentry->d_inode->i_mutex locked.
L
Linus Torvalds 已提交
1848 1849 1850
 */
struct dentry *lookup_create(struct nameidata *nd, int is_dir)
{
1851
	struct dentry *dentry = ERR_PTR(-EEXIST);
L
Linus Torvalds 已提交
1852

I
Ingo Molnar 已提交
1853
	mutex_lock_nested(&nd->dentry->d_inode->i_mutex, I_MUTEX_PARENT);
1854 1855 1856 1857
	/*
	 * Yucky last component or no last component at all?
	 * (foo/., foo/.., /////)
	 */
L
Linus Torvalds 已提交
1858 1859 1860
	if (nd->last_type != LAST_NORM)
		goto fail;
	nd->flags &= ~LOOKUP_PARENT;
1861 1862
	nd->flags |= LOOKUP_CREATE;
	nd->intent.open.flags = O_EXCL;
1863 1864 1865 1866

	/*
	 * Do the final lookup.
	 */
1867
	dentry = lookup_hash(nd);
L
Linus Torvalds 已提交
1868 1869
	if (IS_ERR(dentry))
		goto fail;
1870 1871 1872 1873 1874 1875 1876

	/*
	 * Special case - lookup gave negative, but... we had foo/bar/
	 * From the vfs_mknod() POV we just have a negative dentry -
	 * all is fine. Let's be bastards - you had / on the end, you've
	 * been asking for (non-existent) directory. -ENOENT for you.
	 */
L
Linus Torvalds 已提交
1877 1878 1879 1880 1881 1882 1883 1884 1885
	if (!is_dir && nd->last.name[nd->last.len] && !dentry->d_inode)
		goto enoent;
	return dentry;
enoent:
	dput(dentry);
	dentry = ERR_PTR(-ENOENT);
fail:
	return dentry;
}
1886
EXPORT_SYMBOL_GPL(lookup_create);
L
Linus Torvalds 已提交
1887 1888 1889 1890 1891 1892 1893 1894 1895 1896 1897 1898 1899 1900 1901 1902 1903 1904 1905 1906

int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
{
	int error = may_create(dir, dentry, NULL);

	if (error)
		return error;

	if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD))
		return -EPERM;

	if (!dir->i_op || !dir->i_op->mknod)
		return -EPERM;

	error = security_inode_mknod(dir, dentry, mode, dev);
	if (error)
		return error;

	DQUOT_INIT(dir);
	error = dir->i_op->mknod(dir, dentry, mode, dev);
1907
	if (!error)
1908
		fsnotify_create(dir, dentry);
L
Linus Torvalds 已提交
1909 1910 1911
	return error;
}

1912 1913
asmlinkage long sys_mknodat(int dfd, const char __user *filename, int mode,
				unsigned dev)
L
Linus Torvalds 已提交
1914 1915 1916 1917 1918 1919 1920 1921 1922 1923 1924 1925
{
	int error = 0;
	char * tmp;
	struct dentry * dentry;
	struct nameidata nd;

	if (S_ISDIR(mode))
		return -EPERM;
	tmp = getname(filename);
	if (IS_ERR(tmp))
		return PTR_ERR(tmp);

1926
	error = do_path_lookup(dfd, tmp, LOOKUP_PARENT, &nd);
L
Linus Torvalds 已提交
1927 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953
	if (error)
		goto out;
	dentry = lookup_create(&nd, 0);
	error = PTR_ERR(dentry);

	if (!IS_POSIXACL(nd.dentry->d_inode))
		mode &= ~current->fs->umask;
	if (!IS_ERR(dentry)) {
		switch (mode & S_IFMT) {
		case 0: case S_IFREG:
			error = vfs_create(nd.dentry->d_inode,dentry,mode,&nd);
			break;
		case S_IFCHR: case S_IFBLK:
			error = vfs_mknod(nd.dentry->d_inode,dentry,mode,
					new_decode_dev(dev));
			break;
		case S_IFIFO: case S_IFSOCK:
			error = vfs_mknod(nd.dentry->d_inode,dentry,mode,0);
			break;
		case S_IFDIR:
			error = -EPERM;
			break;
		default:
			error = -EINVAL;
		}
		dput(dentry);
	}
1954
	mutex_unlock(&nd.dentry->d_inode->i_mutex);
L
Linus Torvalds 已提交
1955 1956 1957 1958 1959 1960 1961
	path_release(&nd);
out:
	putname(tmp);

	return error;
}

1962 1963 1964 1965 1966
asmlinkage long sys_mknod(const char __user *filename, int mode, unsigned dev)
{
	return sys_mknodat(AT_FDCWD, filename, mode, dev);
}

L
Linus Torvalds 已提交
1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983
int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
{
	int error = may_create(dir, dentry, NULL);

	if (error)
		return error;

	if (!dir->i_op || !dir->i_op->mkdir)
		return -EPERM;

	mode &= (S_IRWXUGO|S_ISVTX);
	error = security_inode_mkdir(dir, dentry, mode);
	if (error)
		return error;

	DQUOT_INIT(dir);
	error = dir->i_op->mkdir(dir, dentry, mode);
1984
	if (!error)
1985
		fsnotify_mkdir(dir, dentry);
L
Linus Torvalds 已提交
1986 1987 1988
	return error;
}

1989
asmlinkage long sys_mkdirat(int dfd, const char __user *pathname, int mode)
L
Linus Torvalds 已提交
1990 1991 1992
{
	int error = 0;
	char * tmp;
1993 1994
	struct dentry *dentry;
	struct nameidata nd;
L
Linus Torvalds 已提交
1995 1996 1997

	tmp = getname(pathname);
	error = PTR_ERR(tmp);
1998 1999
	if (IS_ERR(tmp))
		goto out_err;
L
Linus Torvalds 已提交
2000

2001 2002 2003 2004 2005 2006 2007
	error = do_path_lookup(dfd, tmp, LOOKUP_PARENT, &nd);
	if (error)
		goto out;
	dentry = lookup_create(&nd, 1);
	error = PTR_ERR(dentry);
	if (IS_ERR(dentry))
		goto out_unlock;
L
Linus Torvalds 已提交
2008

2009 2010 2011 2012 2013 2014 2015 2016 2017 2018
	if (!IS_POSIXACL(nd.dentry->d_inode))
		mode &= ~current->fs->umask;
	error = vfs_mkdir(nd.dentry->d_inode, dentry, mode);
	dput(dentry);
out_unlock:
	mutex_unlock(&nd.dentry->d_inode->i_mutex);
	path_release(&nd);
out:
	putname(tmp);
out_err:
L
Linus Torvalds 已提交
2019 2020 2021
	return error;
}

2022 2023 2024 2025 2026
asmlinkage long sys_mkdir(const char __user *pathname, int mode)
{
	return sys_mkdirat(AT_FDCWD, pathname, mode);
}

L
Linus Torvalds 已提交
2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043 2044
/*
 * We try to drop the dentry early: we should have
 * a usage count of 2 if we're the only user of this
 * dentry, and if that is true (possibly after pruning
 * the dcache), then we drop the dentry now.
 *
 * A low-level filesystem can, if it choses, legally
 * do a
 *
 *	if (!d_unhashed(dentry))
 *		return -EBUSY;
 *
 * if it cannot handle the case of removing a directory
 * that is still in use by something else..
 */
void dentry_unhash(struct dentry *dentry)
{
	dget(dentry);
2045
	shrink_dcache_parent(dentry);
L
Linus Torvalds 已提交
2046 2047 2048 2049 2050 2051 2052 2053 2054 2055 2056 2057 2058 2059 2060 2061 2062 2063 2064 2065
	spin_lock(&dcache_lock);
	spin_lock(&dentry->d_lock);
	if (atomic_read(&dentry->d_count) == 2)
		__d_drop(dentry);
	spin_unlock(&dentry->d_lock);
	spin_unlock(&dcache_lock);
}

int vfs_rmdir(struct inode *dir, struct dentry *dentry)
{
	int error = may_delete(dir, dentry, 1);

	if (error)
		return error;

	if (!dir->i_op || !dir->i_op->rmdir)
		return -EPERM;

	DQUOT_INIT(dir);

2066
	mutex_lock(&dentry->d_inode->i_mutex);
L
Linus Torvalds 已提交
2067 2068 2069 2070 2071 2072 2073 2074 2075 2076 2077
	dentry_unhash(dentry);
	if (d_mountpoint(dentry))
		error = -EBUSY;
	else {
		error = security_inode_rmdir(dir, dentry);
		if (!error) {
			error = dir->i_op->rmdir(dir, dentry);
			if (!error)
				dentry->d_inode->i_flags |= S_DEAD;
		}
	}
2078
	mutex_unlock(&dentry->d_inode->i_mutex);
L
Linus Torvalds 已提交
2079 2080 2081 2082 2083 2084 2085 2086
	if (!error) {
		d_delete(dentry);
	}
	dput(dentry);

	return error;
}

2087
static long do_rmdir(int dfd, const char __user *pathname)
L
Linus Torvalds 已提交
2088 2089 2090 2091 2092 2093 2094 2095 2096 2097
{
	int error = 0;
	char * name;
	struct dentry *dentry;
	struct nameidata nd;

	name = getname(pathname);
	if(IS_ERR(name))
		return PTR_ERR(name);

2098
	error = do_path_lookup(dfd, name, LOOKUP_PARENT, &nd);
L
Linus Torvalds 已提交
2099 2100 2101 2102 2103 2104 2105 2106 2107 2108 2109 2110 2111 2112
	if (error)
		goto exit;

	switch(nd.last_type) {
		case LAST_DOTDOT:
			error = -ENOTEMPTY;
			goto exit1;
		case LAST_DOT:
			error = -EINVAL;
			goto exit1;
		case LAST_ROOT:
			error = -EBUSY;
			goto exit1;
	}
I
Ingo Molnar 已提交
2113
	mutex_lock_nested(&nd.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
2114
	dentry = lookup_hash(&nd);
L
Linus Torvalds 已提交
2115
	error = PTR_ERR(dentry);
2116 2117 2118 2119 2120
	if (IS_ERR(dentry))
		goto exit2;
	error = vfs_rmdir(nd.dentry->d_inode, dentry);
	dput(dentry);
exit2:
2121
	mutex_unlock(&nd.dentry->d_inode->i_mutex);
L
Linus Torvalds 已提交
2122 2123 2124 2125 2126 2127 2128
exit1:
	path_release(&nd);
exit:
	putname(name);
	return error;
}

2129 2130 2131 2132 2133
asmlinkage long sys_rmdir(const char __user *pathname)
{
	return do_rmdir(AT_FDCWD, pathname);
}

L
Linus Torvalds 已提交
2134 2135 2136 2137 2138 2139 2140 2141 2142 2143 2144 2145
int vfs_unlink(struct inode *dir, struct dentry *dentry)
{
	int error = may_delete(dir, dentry, 0);

	if (error)
		return error;

	if (!dir->i_op || !dir->i_op->unlink)
		return -EPERM;

	DQUOT_INIT(dir);

2146
	mutex_lock(&dentry->d_inode->i_mutex);
L
Linus Torvalds 已提交
2147 2148 2149 2150 2151 2152 2153
	if (d_mountpoint(dentry))
		error = -EBUSY;
	else {
		error = security_inode_unlink(dir, dentry);
		if (!error)
			error = dir->i_op->unlink(dir, dentry);
	}
2154
	mutex_unlock(&dentry->d_inode->i_mutex);
L
Linus Torvalds 已提交
2155 2156 2157

	/* We don't d_delete() NFS sillyrenamed files--they still exist. */
	if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) {
J
John McCutchan 已提交
2158
		d_delete(dentry);
L
Linus Torvalds 已提交
2159
	}
R
Robert Love 已提交
2160

L
Linus Torvalds 已提交
2161 2162 2163 2164 2165
	return error;
}

/*
 * Make sure that the actual truncation of the file will occur outside its
2166
 * directory's i_mutex.  Truncate can take a long time if there is a lot of
L
Linus Torvalds 已提交
2167 2168 2169
 * writeout happening, and we don't want to prevent access to the directory
 * while waiting on the I/O.
 */
2170
static long do_unlinkat(int dfd, const char __user *pathname)
L
Linus Torvalds 已提交
2171 2172 2173 2174 2175 2176 2177 2178 2179 2180 2181
{
	int error = 0;
	char * name;
	struct dentry *dentry;
	struct nameidata nd;
	struct inode *inode = NULL;

	name = getname(pathname);
	if(IS_ERR(name))
		return PTR_ERR(name);

2182
	error = do_path_lookup(dfd, name, LOOKUP_PARENT, &nd);
L
Linus Torvalds 已提交
2183 2184 2185 2186 2187
	if (error)
		goto exit;
	error = -EISDIR;
	if (nd.last_type != LAST_NORM)
		goto exit1;
I
Ingo Molnar 已提交
2188
	mutex_lock_nested(&nd.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
2189
	dentry = lookup_hash(&nd);
L
Linus Torvalds 已提交
2190 2191 2192 2193 2194 2195 2196 2197 2198 2199 2200 2201
	error = PTR_ERR(dentry);
	if (!IS_ERR(dentry)) {
		/* Why not before? Because we want correct error value */
		if (nd.last.name[nd.last.len])
			goto slashes;
		inode = dentry->d_inode;
		if (inode)
			atomic_inc(&inode->i_count);
		error = vfs_unlink(nd.dentry->d_inode, dentry);
	exit2:
		dput(dentry);
	}
2202
	mutex_unlock(&nd.dentry->d_inode->i_mutex);
L
Linus Torvalds 已提交
2203 2204 2205 2206 2207 2208 2209 2210 2211 2212 2213 2214 2215 2216
	if (inode)
		iput(inode);	/* truncate the inode here */
exit1:
	path_release(&nd);
exit:
	putname(name);
	return error;

slashes:
	error = !dentry->d_inode ? -ENOENT :
		S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR;
	goto exit2;
}

2217 2218 2219 2220 2221 2222 2223 2224 2225 2226 2227 2228 2229 2230 2231 2232
asmlinkage long sys_unlinkat(int dfd, const char __user *pathname, int flag)
{
	if ((flag & ~AT_REMOVEDIR) != 0)
		return -EINVAL;

	if (flag & AT_REMOVEDIR)
		return do_rmdir(dfd, pathname);

	return do_unlinkat(dfd, pathname);
}

asmlinkage long sys_unlink(const char __user *pathname)
{
	return do_unlinkat(AT_FDCWD, pathname);
}

L
Linus Torvalds 已提交
2233 2234 2235 2236 2237 2238 2239 2240 2241 2242 2243 2244 2245 2246 2247 2248
int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname, int mode)
{
	int error = may_create(dir, dentry, NULL);

	if (error)
		return error;

	if (!dir->i_op || !dir->i_op->symlink)
		return -EPERM;

	error = security_inode_symlink(dir, dentry, oldname);
	if (error)
		return error;

	DQUOT_INIT(dir);
	error = dir->i_op->symlink(dir, dentry, oldname);
2249
	if (!error)
2250
		fsnotify_create(dir, dentry);
L
Linus Torvalds 已提交
2251 2252 2253
	return error;
}

2254 2255
asmlinkage long sys_symlinkat(const char __user *oldname,
			      int newdfd, const char __user *newname)
L
Linus Torvalds 已提交
2256 2257 2258 2259
{
	int error = 0;
	char * from;
	char * to;
2260 2261
	struct dentry *dentry;
	struct nameidata nd;
L
Linus Torvalds 已提交
2262 2263 2264 2265 2266 2267

	from = getname(oldname);
	if(IS_ERR(from))
		return PTR_ERR(from);
	to = getname(newname);
	error = PTR_ERR(to);
2268 2269
	if (IS_ERR(to))
		goto out_putname;
L
Linus Torvalds 已提交
2270

2271 2272 2273 2274 2275 2276 2277 2278 2279 2280 2281 2282 2283
	error = do_path_lookup(newdfd, to, LOOKUP_PARENT, &nd);
	if (error)
		goto out;
	dentry = lookup_create(&nd, 0);
	error = PTR_ERR(dentry);
	if (IS_ERR(dentry))
		goto out_unlock;

	error = vfs_symlink(nd.dentry->d_inode, dentry, from, S_IALLUGO);
	dput(dentry);
out_unlock:
	mutex_unlock(&nd.dentry->d_inode->i_mutex);
	path_release(&nd);
L
Linus Torvalds 已提交
2284
out:
2285 2286
	putname(to);
out_putname:
L
Linus Torvalds 已提交
2287 2288 2289 2290
	putname(from);
	return error;
}

2291 2292 2293 2294 2295
asmlinkage long sys_symlink(const char __user *oldname, const char __user *newname)
{
	return sys_symlinkat(oldname, AT_FDCWD, newname);
}

L
Linus Torvalds 已提交
2296 2297 2298 2299 2300 2301 2302 2303 2304 2305 2306 2307 2308 2309 2310 2311 2312 2313 2314 2315 2316 2317 2318 2319 2320 2321 2322 2323 2324
int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry)
{
	struct inode *inode = old_dentry->d_inode;
	int error;

	if (!inode)
		return -ENOENT;

	error = may_create(dir, new_dentry, NULL);
	if (error)
		return error;

	if (dir->i_sb != inode->i_sb)
		return -EXDEV;

	/*
	 * A link to an append-only or immutable file cannot be created.
	 */
	if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
		return -EPERM;
	if (!dir->i_op || !dir->i_op->link)
		return -EPERM;
	if (S_ISDIR(old_dentry->d_inode->i_mode))
		return -EPERM;

	error = security_inode_link(old_dentry, dir, new_dentry);
	if (error)
		return error;

2325
	mutex_lock(&old_dentry->d_inode->i_mutex);
L
Linus Torvalds 已提交
2326 2327
	DQUOT_INIT(dir);
	error = dir->i_op->link(old_dentry, dir, new_dentry);
2328
	mutex_unlock(&old_dentry->d_inode->i_mutex);
2329
	if (!error)
2330
		fsnotify_create(dir, new_dentry);
L
Linus Torvalds 已提交
2331 2332 2333 2334 2335 2336 2337 2338 2339 2340 2341 2342
	return error;
}

/*
 * Hardlinks are often used in delicate situations.  We avoid
 * security-related surprises by not following symlinks on the
 * newname.  --KAB
 *
 * We don't follow them on the oldname either to be compatible
 * with linux 2.0, and to avoid hard-linking to directories
 * and other special files.  --ADM
 */
2343
asmlinkage long sys_linkat(int olddfd, const char __user *oldname,
2344 2345
			   int newdfd, const char __user *newname,
			   int flags)
L
Linus Torvalds 已提交
2346 2347 2348 2349 2350 2351
{
	struct dentry *new_dentry;
	struct nameidata nd, old_nd;
	int error;
	char * to;

2352
	if ((flags & ~AT_SYMLINK_FOLLOW) != 0)
2353 2354
		return -EINVAL;

L
Linus Torvalds 已提交
2355 2356 2357 2358
	to = getname(newname);
	if (IS_ERR(to))
		return PTR_ERR(to);

2359 2360 2361
	error = __user_walk_fd(olddfd, oldname,
			       flags & AT_SYMLINK_FOLLOW ? LOOKUP_FOLLOW : 0,
			       &old_nd);
L
Linus Torvalds 已提交
2362 2363
	if (error)
		goto exit;
2364
	error = do_path_lookup(newdfd, to, LOOKUP_PARENT, &nd);
L
Linus Torvalds 已提交
2365 2366 2367 2368 2369 2370 2371
	if (error)
		goto out;
	error = -EXDEV;
	if (old_nd.mnt != nd.mnt)
		goto out_release;
	new_dentry = lookup_create(&nd, 0);
	error = PTR_ERR(new_dentry);
2372 2373 2374 2375 2376
	if (IS_ERR(new_dentry))
		goto out_unlock;
	error = vfs_link(old_nd.dentry, nd.dentry->d_inode, new_dentry);
	dput(new_dentry);
out_unlock:
2377
	mutex_unlock(&nd.dentry->d_inode->i_mutex);
L
Linus Torvalds 已提交
2378 2379 2380 2381 2382 2383 2384 2385 2386 2387
out_release:
	path_release(&nd);
out:
	path_release(&old_nd);
exit:
	putname(to);

	return error;
}

2388 2389
asmlinkage long sys_link(const char __user *oldname, const char __user *newname)
{
2390
	return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0);
2391 2392
}

L
Linus Torvalds 已提交
2393 2394 2395 2396 2397 2398 2399
/*
 * The worst of all namespace operations - renaming directory. "Perverted"
 * doesn't even start to describe it. Somebody in UCB had a heck of a trip...
 * Problems:
 *	a) we can get into loop creation. Check is done in is_subdir().
 *	b) race potential - two innocent renames can create a loop together.
 *	   That's where 4.4 screws up. Current fix: serialization on
2400
 *	   sb->s_vfs_rename_mutex. We might be more accurate, but that's another
L
Linus Torvalds 已提交
2401 2402
 *	   story.
 *	c) we have to lock _three_ objects - parents and victim (if it exists).
2403
 *	   And that - after we got ->i_mutex on parents (until then we don't know
L
Linus Torvalds 已提交
2404 2405
 *	   whether the target exists).  Solution: try to be smart with locking
 *	   order for inodes.  We rely on the fact that tree topology may change
2406
 *	   only under ->s_vfs_rename_mutex _and_ that parent of the object we
L
Linus Torvalds 已提交
2407 2408 2409
 *	   move will be locked.  Thus we can rank directories by the tree
 *	   (ancestors first) and rank all non-directories after them.
 *	   That works since everybody except rename does "lock parent, lookup,
2410
 *	   lock child" and rename is under ->s_vfs_rename_mutex.
L
Linus Torvalds 已提交
2411 2412 2413 2414 2415 2416 2417 2418 2419
 *	   HOWEVER, it relies on the assumption that any object with ->lookup()
 *	   has no more than 1 dentry.  If "hybrid" objects will ever appear,
 *	   we'd better make sure that there's no link(2) for them.
 *	d) some filesystems don't support opened-but-unlinked directories,
 *	   either because of layout or because they are not ready to deal with
 *	   all cases correctly. The latter will be fixed (taking this sort of
 *	   stuff into VFS), but the former is not going away. Solution: the same
 *	   trick as in rmdir().
 *	e) conversion from fhandle to dentry may come in the wrong moment - when
2420
 *	   we are removing the target. Solution: we will have to grab ->i_mutex
L
Linus Torvalds 已提交
2421
 *	   in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
2422
 *	   ->i_mutex on parents, which works but leads to some truely excessive
L
Linus Torvalds 已提交
2423 2424
 *	   locking].
 */
A
Adrian Bunk 已提交
2425 2426
static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry,
			  struct inode *new_dir, struct dentry *new_dentry)
L
Linus Torvalds 已提交
2427 2428 2429 2430 2431 2432 2433 2434 2435 2436 2437 2438 2439 2440 2441 2442 2443 2444 2445 2446
{
	int error = 0;
	struct inode *target;

	/*
	 * If we are going to change the parent - check write permissions,
	 * we'll need to flip '..'.
	 */
	if (new_dir != old_dir) {
		error = permission(old_dentry->d_inode, MAY_WRITE, NULL);
		if (error)
			return error;
	}

	error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry);
	if (error)
		return error;

	target = new_dentry->d_inode;
	if (target) {
2447
		mutex_lock(&target->i_mutex);
L
Linus Torvalds 已提交
2448 2449 2450 2451 2452 2453 2454 2455 2456
		dentry_unhash(new_dentry);
	}
	if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry))
		error = -EBUSY;
	else 
		error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
	if (target) {
		if (!error)
			target->i_flags |= S_DEAD;
2457
		mutex_unlock(&target->i_mutex);
L
Linus Torvalds 已提交
2458 2459 2460 2461
		if (d_unhashed(new_dentry))
			d_rehash(new_dentry);
		dput(new_dentry);
	}
2462
	if (!error)
2463 2464
		if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE))
			d_move(old_dentry,new_dentry);
L
Linus Torvalds 已提交
2465 2466 2467
	return error;
}

A
Adrian Bunk 已提交
2468 2469
static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry,
			    struct inode *new_dir, struct dentry *new_dentry)
L
Linus Torvalds 已提交
2470 2471 2472 2473 2474 2475 2476 2477 2478 2479 2480
{
	struct inode *target;
	int error;

	error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry);
	if (error)
		return error;

	dget(new_dentry);
	target = new_dentry->d_inode;
	if (target)
2481
		mutex_lock(&target->i_mutex);
L
Linus Torvalds 已提交
2482 2483 2484 2485 2486
	if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry))
		error = -EBUSY;
	else
		error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
	if (!error) {
2487
		if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE))
L
Linus Torvalds 已提交
2488 2489 2490
			d_move(old_dentry, new_dentry);
	}
	if (target)
2491
		mutex_unlock(&target->i_mutex);
L
Linus Torvalds 已提交
2492 2493 2494 2495 2496 2497 2498 2499 2500
	dput(new_dentry);
	return error;
}

int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
	       struct inode *new_dir, struct dentry *new_dentry)
{
	int error;
	int is_dir = S_ISDIR(old_dentry->d_inode->i_mode);
R
Robert Love 已提交
2501
	const char *old_name;
L
Linus Torvalds 已提交
2502 2503 2504 2505 2506 2507 2508 2509 2510 2511 2512 2513 2514 2515 2516 2517 2518 2519 2520 2521 2522

	if (old_dentry->d_inode == new_dentry->d_inode)
 		return 0;
 
	error = may_delete(old_dir, old_dentry, is_dir);
	if (error)
		return error;

	if (!new_dentry->d_inode)
		error = may_create(new_dir, new_dentry, NULL);
	else
		error = may_delete(new_dir, new_dentry, is_dir);
	if (error)
		return error;

	if (!old_dir->i_op || !old_dir->i_op->rename)
		return -EPERM;

	DQUOT_INIT(old_dir);
	DQUOT_INIT(new_dir);

R
Robert Love 已提交
2523 2524
	old_name = fsnotify_oldname_init(old_dentry->d_name.name);

L
Linus Torvalds 已提交
2525 2526 2527 2528 2529
	if (is_dir)
		error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry);
	else
		error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry);
	if (!error) {
R
Robert Love 已提交
2530
		const char *new_name = old_dentry->d_name.name;
2531 2532
		fsnotify_move(old_dir, new_dir, old_name, new_name, is_dir,
			      new_dentry->d_inode, old_dentry->d_inode);
L
Linus Torvalds 已提交
2533
	}
R
Robert Love 已提交
2534 2535
	fsnotify_oldname_free(old_name);

L
Linus Torvalds 已提交
2536 2537 2538
	return error;
}

2539 2540
static int do_rename(int olddfd, const char *oldname,
			int newdfd, const char *newname)
L
Linus Torvalds 已提交
2541 2542 2543 2544 2545 2546 2547
{
	int error = 0;
	struct dentry * old_dir, * new_dir;
	struct dentry * old_dentry, *new_dentry;
	struct dentry * trap;
	struct nameidata oldnd, newnd;

2548
	error = do_path_lookup(olddfd, oldname, LOOKUP_PARENT, &oldnd);
L
Linus Torvalds 已提交
2549 2550 2551
	if (error)
		goto exit;

2552
	error = do_path_lookup(newdfd, newname, LOOKUP_PARENT, &newnd);
L
Linus Torvalds 已提交
2553 2554 2555 2556 2557 2558 2559 2560 2561 2562 2563 2564 2565 2566 2567 2568 2569 2570
	if (error)
		goto exit1;

	error = -EXDEV;
	if (oldnd.mnt != newnd.mnt)
		goto exit2;

	old_dir = oldnd.dentry;
	error = -EBUSY;
	if (oldnd.last_type != LAST_NORM)
		goto exit2;

	new_dir = newnd.dentry;
	if (newnd.last_type != LAST_NORM)
		goto exit2;

	trap = lock_rename(new_dir, old_dir);

2571
	old_dentry = lookup_hash(&oldnd);
L
Linus Torvalds 已提交
2572 2573 2574 2575 2576 2577 2578 2579 2580 2581 2582 2583 2584 2585 2586 2587 2588 2589 2590
	error = PTR_ERR(old_dentry);
	if (IS_ERR(old_dentry))
		goto exit3;
	/* source must exist */
	error = -ENOENT;
	if (!old_dentry->d_inode)
		goto exit4;
	/* unless the source is a directory trailing slashes give -ENOTDIR */
	if (!S_ISDIR(old_dentry->d_inode->i_mode)) {
		error = -ENOTDIR;
		if (oldnd.last.name[oldnd.last.len])
			goto exit4;
		if (newnd.last.name[newnd.last.len])
			goto exit4;
	}
	/* source should not be ancestor of target */
	error = -EINVAL;
	if (old_dentry == trap)
		goto exit4;
2591
	new_dentry = lookup_hash(&newnd);
L
Linus Torvalds 已提交
2592 2593 2594 2595 2596 2597 2598 2599 2600 2601 2602 2603 2604 2605 2606 2607 2608 2609 2610 2611 2612 2613 2614 2615
	error = PTR_ERR(new_dentry);
	if (IS_ERR(new_dentry))
		goto exit4;
	/* target should not be an ancestor of source */
	error = -ENOTEMPTY;
	if (new_dentry == trap)
		goto exit5;

	error = vfs_rename(old_dir->d_inode, old_dentry,
				   new_dir->d_inode, new_dentry);
exit5:
	dput(new_dentry);
exit4:
	dput(old_dentry);
exit3:
	unlock_rename(new_dir, old_dir);
exit2:
	path_release(&newnd);
exit1:
	path_release(&oldnd);
exit:
	return error;
}

2616 2617
asmlinkage long sys_renameat(int olddfd, const char __user *oldname,
			     int newdfd, const char __user *newname)
L
Linus Torvalds 已提交
2618 2619 2620 2621 2622 2623 2624 2625 2626 2627 2628
{
	int error;
	char * from;
	char * to;

	from = getname(oldname);
	if(IS_ERR(from))
		return PTR_ERR(from);
	to = getname(newname);
	error = PTR_ERR(to);
	if (!IS_ERR(to)) {
2629
		error = do_rename(olddfd, from, newdfd, to);
L
Linus Torvalds 已提交
2630 2631 2632 2633 2634 2635
		putname(to);
	}
	putname(from);
	return error;
}

2636 2637 2638 2639 2640
asmlinkage long sys_rename(const char __user *oldname, const char __user *newname)
{
	return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname);
}

L
Linus Torvalds 已提交
2641 2642 2643 2644 2645 2646 2647 2648 2649 2650 2651 2652 2653 2654 2655 2656 2657 2658 2659 2660 2661 2662 2663 2664 2665
int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link)
{
	int len;

	len = PTR_ERR(link);
	if (IS_ERR(link))
		goto out;

	len = strlen(link);
	if (len > (unsigned) buflen)
		len = buflen;
	if (copy_to_user(buffer, link, len))
		len = -EFAULT;
out:
	return len;
}

/*
 * A helper for ->readlink().  This should be used *ONLY* for symlinks that
 * have ->follow_link() touching nd only in nd_set_link().  Using (or not
 * using) it for any given inode is up to filesystem.
 */
int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen)
{
	struct nameidata nd;
2666 2667
	void *cookie;

L
Linus Torvalds 已提交
2668
	nd.depth = 0;
2669 2670 2671
	cookie = dentry->d_inode->i_op->follow_link(dentry, &nd);
	if (!IS_ERR(cookie)) {
		int res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd));
L
Linus Torvalds 已提交
2672
		if (dentry->d_inode->i_op->put_link)
2673 2674
			dentry->d_inode->i_op->put_link(dentry, &nd, cookie);
		cookie = ERR_PTR(res);
L
Linus Torvalds 已提交
2675
	}
2676
	return PTR_ERR(cookie);
L
Linus Torvalds 已提交
2677 2678 2679 2680 2681 2682 2683 2684 2685 2686 2687 2688
}

int vfs_follow_link(struct nameidata *nd, const char *link)
{
	return __vfs_follow_link(nd, link);
}

/* get the link contents into pagecache */
static char *page_getlink(struct dentry * dentry, struct page **ppage)
{
	struct page * page;
	struct address_space *mapping = dentry->d_inode->i_mapping;
2689
	page = read_mapping_page(mapping, 0, NULL);
L
Linus Torvalds 已提交
2690
	if (IS_ERR(page))
2691
		return (char*)page;
L
Linus Torvalds 已提交
2692 2693 2694 2695 2696 2697 2698 2699 2700 2701 2702 2703 2704 2705 2706 2707
	*ppage = page;
	return kmap(page);
}

int page_readlink(struct dentry *dentry, char __user *buffer, int buflen)
{
	struct page *page = NULL;
	char *s = page_getlink(dentry, &page);
	int res = vfs_readlink(dentry,buffer,buflen,s);
	if (page) {
		kunmap(page);
		page_cache_release(page);
	}
	return res;
}

2708
void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd)
L
Linus Torvalds 已提交
2709
{
2710
	struct page *page = NULL;
L
Linus Torvalds 已提交
2711
	nd_set_link(nd, page_getlink(dentry, &page));
2712
	return page;
L
Linus Torvalds 已提交
2713 2714
}

2715
void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
L
Linus Torvalds 已提交
2716
{
2717 2718 2719
	struct page *page = cookie;

	if (page) {
L
Linus Torvalds 已提交
2720 2721 2722 2723 2724
		kunmap(page);
		page_cache_release(page);
	}
}

2725 2726
int __page_symlink(struct inode *inode, const char *symname, int len,
		gfp_t gfp_mask)
L
Linus Torvalds 已提交
2727 2728
{
	struct address_space *mapping = inode->i_mapping;
2729
	struct page *page;
2730
	int err;
L
Linus Torvalds 已提交
2731 2732
	char *kaddr;

2733
retry:
2734
	err = -ENOMEM;
2735
	page = find_or_create_page(mapping, 0, gfp_mask);
L
Linus Torvalds 已提交
2736 2737 2738
	if (!page)
		goto fail;
	err = mapping->a_ops->prepare_write(NULL, page, 0, len-1);
2739 2740 2741 2742
	if (err == AOP_TRUNCATED_PAGE) {
		page_cache_release(page);
		goto retry;
	}
L
Linus Torvalds 已提交
2743 2744 2745 2746 2747
	if (err)
		goto fail_map;
	kaddr = kmap_atomic(page, KM_USER0);
	memcpy(kaddr, symname, len-1);
	kunmap_atomic(kaddr, KM_USER0);
2748 2749 2750 2751 2752 2753 2754
	err = mapping->a_ops->commit_write(NULL, page, 0, len-1);
	if (err == AOP_TRUNCATED_PAGE) {
		page_cache_release(page);
		goto retry;
	}
	if (err)
		goto fail_map;
L
Linus Torvalds 已提交
2755 2756 2757 2758 2759 2760 2761 2762 2763
	/*
	 * Notice that we are _not_ going to block here - end of page is
	 * unmapped, so this will only try to map the rest of page, see
	 * that it is unmapped (typically even will not look into inode -
	 * ->i_size will be enough for everything) and zero it out.
	 * OTOH it's obviously correct and should make the page up-to-date.
	 */
	if (!PageUptodate(page)) {
		err = mapping->a_ops->readpage(NULL, page);
2764 2765
		if (err != AOP_TRUNCATED_PAGE)
			wait_on_page_locked(page);
L
Linus Torvalds 已提交
2766 2767 2768 2769 2770 2771 2772 2773 2774 2775 2776 2777 2778 2779 2780
	} else {
		unlock_page(page);
	}
	page_cache_release(page);
	if (err < 0)
		goto fail;
	mark_inode_dirty(inode);
	return 0;
fail_map:
	unlock_page(page);
	page_cache_release(page);
fail:
	return err;
}

2781 2782 2783 2784 2785 2786
int page_symlink(struct inode *inode, const char *symname, int len)
{
	return __page_symlink(inode, symname, len,
			mapping_gfp_mask(inode->i_mapping));
}

2787
const struct inode_operations page_symlink_inode_operations = {
L
Linus Torvalds 已提交
2788 2789 2790 2791 2792 2793
	.readlink	= generic_readlink,
	.follow_link	= page_follow_link_light,
	.put_link	= page_put_link,
};

EXPORT_SYMBOL(__user_walk);
2794
EXPORT_SYMBOL(__user_walk_fd);
L
Linus Torvalds 已提交
2795 2796 2797 2798 2799 2800 2801 2802 2803
EXPORT_SYMBOL(follow_down);
EXPORT_SYMBOL(follow_up);
EXPORT_SYMBOL(get_write_access); /* binfmt_aout */
EXPORT_SYMBOL(getname);
EXPORT_SYMBOL(lock_rename);
EXPORT_SYMBOL(lookup_one_len);
EXPORT_SYMBOL(page_follow_link_light);
EXPORT_SYMBOL(page_put_link);
EXPORT_SYMBOL(page_readlink);
2804
EXPORT_SYMBOL(__page_symlink);
L
Linus Torvalds 已提交
2805 2806 2807
EXPORT_SYMBOL(page_symlink);
EXPORT_SYMBOL(page_symlink_inode_operations);
EXPORT_SYMBOL(path_lookup);
2808
EXPORT_SYMBOL(vfs_path_lookup);
L
Linus Torvalds 已提交
2809 2810 2811
EXPORT_SYMBOL(path_release);
EXPORT_SYMBOL(path_walk);
EXPORT_SYMBOL(permission);
2812
EXPORT_SYMBOL(vfs_permission);
2813
EXPORT_SYMBOL(file_permission);
L
Linus Torvalds 已提交
2814 2815 2816 2817 2818 2819 2820 2821 2822 2823 2824 2825 2826 2827
EXPORT_SYMBOL(unlock_rename);
EXPORT_SYMBOL(vfs_create);
EXPORT_SYMBOL(vfs_follow_link);
EXPORT_SYMBOL(vfs_link);
EXPORT_SYMBOL(vfs_mkdir);
EXPORT_SYMBOL(vfs_mknod);
EXPORT_SYMBOL(generic_permission);
EXPORT_SYMBOL(vfs_readlink);
EXPORT_SYMBOL(vfs_rename);
EXPORT_SYMBOL(vfs_rmdir);
EXPORT_SYMBOL(vfs_symlink);
EXPORT_SYMBOL(vfs_unlink);
EXPORT_SYMBOL(dentry_unhash);
EXPORT_SYMBOL(generic_readlink);