namei.c 66 KB
Newer Older
Linus Torvalds's avatar
Linus Torvalds committed
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>
Robert Love's avatar
Robert Love committed
24
#include <linux/fsnotify.h>
Linus Torvalds's avatar
Linus Torvalds committed
25 26 27 28 29 30
#include <linux/smp_lock.h>
#include <linux/personality.h>
#include <linux/security.h>
#include <linux/syscalls.h>
#include <linux/mount.h>
#include <linux/audit.h>
31
#include <linux/capability.h>
32
#include <linux/file.h>
33 34
#include <linux/fcntl.h>
#include <linux/namei.h>
Linus Torvalds's avatar
Linus Torvalds committed
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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117
#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)
 * implemented.  Let's see if raised priority of ->s_vfs_rename_sem gives
 * 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.
 */
118
static int do_getname(const char __user *filename, char *page)
Linus Torvalds's avatar
Linus Torvalds committed
119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261
{
	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)
{
	if (unlikely(current->audit_context))
		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)
{
	int retval, submask;

	if (mask & MAY_WRITE) {
		umode_t mode = inode->i_mode;

		/*
		 * 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;
	}


	/* 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);
}

262 263 264 265 266 267 268 269 270 271 272 273 274 275 276
/**
 * 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);
}

277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293
/**
 * 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)
{
	return permission(file->f_dentry->d_inode, mask, NULL);
}

Linus Torvalds's avatar
Linus Torvalds committed
294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352
/*
 * 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)
{
	struct inode *inode = file->f_dentry->d_inode;

	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);
353
	mntput_no_expire(nd->mnt);
Linus Torvalds's avatar
Linus Torvalds committed
354 355
}

356 357 358 359 360 361 362 363 364 365 366 367
/**
 * release_open_intent - free up open intent resources
 * @nd: pointer to nameidata
 */
void release_open_intent(struct nameidata *nd)
{
	if (nd->intent.open.file->f_dentry == NULL)
		put_filp(nd->intent.open.file);
	else
		fput(nd->intent.open.file);
}

Linus Torvalds's avatar
Linus Torvalds committed
368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400
/*
 * 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);

	if (dentry && dentry->d_op && dentry->d_op->d_revalidate) {
		if (!dentry->d_op->d_revalidate(dentry, nd) && !d_invalidate(dentry)) {
			dput(dentry);
			dentry = NULL;
		}
	}
	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.
 */
401
static int exec_permission_lite(struct inode *inode,
Linus Torvalds's avatar
Linus Torvalds committed
402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443
				       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;

444
	mutex_lock(&dir->i_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
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
	/*
	 * 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;
		}
470
		mutex_unlock(&dir->i_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
471 472 473 474 475 476 477
		return result;
	}

	/*
	 * Uhhuh! Nasty case: the cache was re-populated while
	 * we waited on the semaphore. Need to revalidate.
	 */
478
	mutex_unlock(&dir->i_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
479 480 481 482 483 484 485 486 487 488 489 490
	if (result->d_op && result->d_op->d_revalidate) {
		if (!result->d_op->d_revalidate(result, nd) && !d_invalidate(result)) {
			dput(result);
			result = ERR_PTR(-ENOENT);
		}
	}
	return result;
}

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

/* SMP-safe */
491
static __always_inline int
Linus Torvalds's avatar
Linus Torvalds committed
492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508
walk_init_root(const char *name, struct nameidata *nd)
{
	read_lock(&current->fs->lock);
	if (current->fs->altroot && !(nd->flags & LOOKUP_NOALT)) {
		nd->mnt = mntget(current->fs->altrootmnt);
		nd->dentry = dget(current->fs->altroot);
		read_unlock(&current->fs->lock);
		if (__emul_lookup_dentry(name,nd))
			return 0;
		read_lock(&current->fs->lock);
	}
	nd->mnt = mntget(current->fs->rootmnt);
	nd->dentry = dget(current->fs->root);
	read_unlock(&current->fs->lock);
	return 1;
}

509
static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link)
Linus Torvalds's avatar
Linus Torvalds committed
510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543
{
	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);
}

Al Viro's avatar
Al Viro committed
544 545 546 547 548
struct path {
	struct vfsmount *mnt;
	struct dentry *dentry;
};

549
static __always_inline int __do_follow_link(struct path *path, struct nameidata *nd)
Linus Torvalds's avatar
Linus Torvalds committed
550 551
{
	int error;
552
	void *cookie;
Al Viro's avatar
Al Viro committed
553
	struct dentry *dentry = path->dentry;
Linus Torvalds's avatar
Linus Torvalds committed
554

Al Viro's avatar
Al Viro committed
555
	touch_atime(path->mnt, dentry);
Linus Torvalds's avatar
Linus Torvalds committed
556
	nd_set_link(nd, NULL);
Al Viro's avatar
Al Viro committed
557

Al Viro's avatar
Al Viro committed
558 559
	if (path->mnt == nd->mnt)
		mntget(path->mnt);
560 561 562
	cookie = dentry->d_inode->i_op->follow_link(dentry, nd);
	error = PTR_ERR(cookie);
	if (!IS_ERR(cookie)) {
Linus Torvalds's avatar
Linus Torvalds committed
563
		char *s = nd_get_link(nd);
564
		error = 0;
Linus Torvalds's avatar
Linus Torvalds committed
565 566 567
		if (s)
			error = __vfs_follow_link(nd, s);
		if (dentry->d_inode->i_op->put_link)
568
			dentry->d_inode->i_op->put_link(dentry, nd, cookie);
Linus Torvalds's avatar
Linus Torvalds committed
569
	}
Al Viro's avatar
Al Viro committed
570 571
	dput(dentry);
	mntput(path->mnt);
Linus Torvalds's avatar
Linus Torvalds committed
572 573 574 575

	return error;
}

Miklos Szeredi's avatar
Miklos Szeredi committed
576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591
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;
}

Linus Torvalds's avatar
Linus Torvalds committed
592 593 594 595 596 597 598
/*
 * 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. 
 */
Al Viro's avatar
Al Viro committed
599
static inline int do_follow_link(struct path *path, struct nameidata *nd)
Linus Torvalds's avatar
Linus Torvalds committed
600 601 602 603 604 605 606 607
{
	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();
Al Viro's avatar
Al Viro committed
608
	err = security_inode_follow_link(path->dentry, nd);
Linus Torvalds's avatar
Linus Torvalds committed
609 610 611 612 613
	if (err)
		goto loop;
	current->link_count++;
	current->total_link_count++;
	nd->depth++;
Al Viro's avatar
Al Viro committed
614
	err = __do_follow_link(path, nd);
Al Viro's avatar
Al Viro committed
615 616
	current->link_count--;
	nd->depth--;
Linus Torvalds's avatar
Linus Torvalds committed
617 618
	return err;
loop:
Miklos Szeredi's avatar
Miklos Szeredi committed
619
	dput_path(path, nd);
Al Viro's avatar
Al Viro committed
620
	path_release(nd);
Linus Torvalds's avatar
Linus Torvalds committed
621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646
	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
 */
Al Viro's avatar
Al Viro committed
647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663
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;
}

Al Viro's avatar
Al Viro committed
664
static void follow_mount(struct vfsmount **mnt, struct dentry **dentry)
Linus Torvalds's avatar
Linus Torvalds committed
665 666 667 668 669
{
	while (d_mountpoint(*dentry)) {
		struct vfsmount *mounted = lookup_mnt(*mnt, *dentry);
		if (!mounted)
			break;
Al Viro's avatar
Al Viro committed
670
		dput(*dentry);
Linus Torvalds's avatar
Linus Torvalds committed
671 672 673 674 675 676 677 678 679
		mntput(*mnt);
		*mnt = mounted;
		*dentry = dget(mounted->mnt_root);
	}
}

/* no need for dcache_lock, as serialization is taken care in
 * namespace.c
 */
Al Viro's avatar
Al Viro committed
680
int follow_down(struct vfsmount **mnt, struct dentry **dentry)
Linus Torvalds's avatar
Linus Torvalds committed
681 682 683 684 685
{
	struct vfsmount *mounted;

	mounted = lookup_mnt(*mnt, *dentry);
	if (mounted) {
Al Viro's avatar
Al Viro committed
686
		dput(*dentry);
Linus Torvalds's avatar
Linus Torvalds committed
687 688 689 690 691 692 693 694
		mntput(*mnt);
		*mnt = mounted;
		*dentry = dget(mounted->mnt_root);
		return 1;
	}
	return 0;
}

695
static __always_inline void follow_dotdot(struct nameidata *nd)
Linus Torvalds's avatar
Linus Torvalds committed
696 697 698
{
	while(1) {
		struct vfsmount *parent;
Al Viro's avatar
Al Viro committed
699
		struct dentry *old = nd->dentry;
Linus Torvalds's avatar
Linus Torvalds committed
700 701

                read_lock(&current->fs->lock);
Al Viro's avatar
Al Viro committed
702 703
		if (nd->dentry == current->fs->root &&
		    nd->mnt == current->fs->rootmnt) {
Linus Torvalds's avatar
Linus Torvalds committed
704 705 706 707 708
                        read_unlock(&current->fs->lock);
			break;
		}
                read_unlock(&current->fs->lock);
		spin_lock(&dcache_lock);
Al Viro's avatar
Al Viro committed
709 710
		if (nd->dentry != nd->mnt->mnt_root) {
			nd->dentry = dget(nd->dentry->d_parent);
Linus Torvalds's avatar
Linus Torvalds committed
711 712 713 714 715 716
			spin_unlock(&dcache_lock);
			dput(old);
			break;
		}
		spin_unlock(&dcache_lock);
		spin_lock(&vfsmount_lock);
Al Viro's avatar
Al Viro committed
717 718
		parent = nd->mnt->mnt_parent;
		if (parent == nd->mnt) {
Linus Torvalds's avatar
Linus Torvalds committed
719 720 721 722
			spin_unlock(&vfsmount_lock);
			break;
		}
		mntget(parent);
Al Viro's avatar
Al Viro committed
723
		nd->dentry = dget(nd->mnt->mnt_mountpoint);
Linus Torvalds's avatar
Linus Torvalds committed
724 725
		spin_unlock(&vfsmount_lock);
		dput(old);
Al Viro's avatar
Al Viro committed
726 727
		mntput(nd->mnt);
		nd->mnt = parent;
Linus Torvalds's avatar
Linus Torvalds committed
728
	}
Al Viro's avatar
Al Viro committed
729
	follow_mount(&nd->mnt, &nd->dentry);
Linus Torvalds's avatar
Linus Torvalds committed
730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749
}

/*
 *  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;
Al Viro's avatar
Al Viro committed
750
	__follow_mount(path);
Linus Torvalds's avatar
Linus Torvalds committed
751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772
	return 0;

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

need_revalidate:
	if (dentry->d_op->d_revalidate(dentry, nd))
		goto done;
	if (d_invalidate(dentry))
		goto done;
	dput(dentry);
	goto need_lookup;

fail:
	return PTR_ERR(dentry);
}

/*
 * Name resolution.
773 774
 * This is the basic name resolution function, turning a pathname into
 * the final dentry. We expect 'base' to be positive and a directory.
Linus Torvalds's avatar
Linus Torvalds committed
775
 *
776 777
 * Returns 0 and nd will have valid dentry and mnt on success.
 * Returns error and drops reference to input namei data on failure.
Linus Torvalds's avatar
Linus Torvalds committed
778 779 780 781 782 783 784 785 786 787 788 789 790 791 792
 */
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)
793
		lookup_flags = LOOKUP_FOLLOW | (nd->flags & LOOKUP_CONTINUE);
Linus Torvalds's avatar
Linus Torvalds committed
794 795 796 797 798 799 800

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

801
		nd->flags |= LOOKUP_CONTINUE;
Linus Torvalds's avatar
Linus Torvalds committed
802
		err = exec_permission_lite(inode, nd);
803 804
		if (err == -EAGAIN)
			err = vfs_permission(nd, MAY_EXEC);
Linus Torvalds's avatar
Linus Torvalds committed
805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837
 		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;
Al Viro's avatar
Al Viro committed
838
				follow_dotdot(nd);
Linus Torvalds's avatar
Linus Torvalds committed
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
				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) {
Al Viro's avatar
Al Viro committed
867
			err = do_follow_link(&next, nd);
Linus Torvalds's avatar
Linus Torvalds committed
868 869 870 871 872 873 874 875 876
			if (err)
				goto return_err;
			err = -ENOENT;
			inode = nd->dentry->d_inode;
			if (!inode)
				break;
			err = -ENOTDIR; 
			if (!inode->i_op)
				break;
Miklos Szeredi's avatar
Miklos Szeredi committed
877 878
		} else
			path_to_nameidata(&next, nd);
Linus Torvalds's avatar
Linus Torvalds committed
879 880 881 882 883 884 885 886 887
		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:
888 889
		/* Clear LOOKUP_CONTINUE iff it was previously unset */
		nd->flags &= lookup_flags | ~LOOKUP_CONTINUE;
Linus Torvalds's avatar
Linus Torvalds committed
890 891 892 893 894 895 896 897
		if (lookup_flags & LOOKUP_PARENT)
			goto lookup_parent;
		if (this.name[0] == '.') switch (this.len) {
			default:
				break;
			case 2:	
				if (this.name[1] != '.')
					break;
Al Viro's avatar
Al Viro committed
898
				follow_dotdot(nd);
Linus Torvalds's avatar
Linus Torvalds committed
899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914
				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) {
Al Viro's avatar
Al Viro committed
915
			err = do_follow_link(&next, nd);
Linus Torvalds's avatar
Linus Torvalds committed
916 917 918
			if (err)
				goto return_err;
			inode = nd->dentry->d_inode;
Miklos Szeredi's avatar
Miklos Szeredi committed
919 920
		} else
			path_to_nameidata(&next, nd);
Linus Torvalds's avatar
Linus Torvalds committed
921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955
		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:
Miklos Szeredi's avatar
Miklos Szeredi committed
956
		dput_path(&next, nd);
Linus Torvalds's avatar
Linus Torvalds committed
957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000
		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);
}

1001 1002 1003 1004
/* 
 * 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;
 */
Linus Torvalds's avatar
Linus Torvalds committed
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 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067
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;
		/*
		 * NAME was not found in alternate root or it's a directory.  Try to find
		 * it in the normal root:
		 */
		nd->last_type = LAST_ROOT;
		read_lock(&current->fs->lock);
		nd->mnt = mntget(current->fs->rootmnt);
		nd->dentry = dget(current->fs->root);
		read_unlock(&current->fs->lock);
		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;

	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:
	write_lock(&current->fs->lock);
	oldmnt = current->fs->altrootmnt;
	olddentry = current->fs->altroot;
	current->fs->altrootmnt = mnt;
	current->fs->altroot = dentry;
	write_unlock(&current->fs->lock);
	if (olddentry) {
		dput(olddentry);
		mntput(oldmnt);
	}
}

1068
/* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
1069 1070
static int fastcall do_path_lookup(int dfd, const char *name,
				unsigned int flags, struct nameidata *nd)
Linus Torvalds's avatar
Linus Torvalds committed
1071
{
1072
	int retval = 0;
1073 1074
	int fput_needed;
	struct file *file;
Linus Torvalds's avatar
Linus Torvalds committed
1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086

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

	read_lock(&current->fs->lock);
	if (*name=='/') {
		if (current->fs->altroot && !(nd->flags & LOOKUP_NOALT)) {
			nd->mnt = mntget(current->fs->altrootmnt);
			nd->dentry = dget(current->fs->altroot);
			read_unlock(&current->fs->lock);
			if (__emul_lookup_dentry(name,nd))
1087
				goto out; /* found in altroot */
Linus Torvalds's avatar
Linus Torvalds committed
1088 1089 1090 1091
			read_lock(&current->fs->lock);
		}
		nd->mnt = mntget(current->fs->rootmnt);
		nd->dentry = dget(current->fs->root);
1092
	} else if (dfd == AT_FDCWD) {
Linus Torvalds's avatar
Linus Torvalds committed
1093 1094
		nd->mnt = mntget(current->fs->pwdmnt);
		nd->dentry = dget(current->fs->pwd);
1095 1096 1097 1098
	} else {
		struct dentry *dentry;

		file = fget_light(dfd, &fput_needed);
1099 1100 1101
		retval = -EBADF;
		if (!file)
			goto unlock_fail;
1102 1103 1104

		dentry = file->f_dentry;

1105 1106 1107
		retval = -ENOTDIR;
		if (!S_ISDIR(dentry->d_inode->i_mode))
			goto fput_unlock_fail;
1108 1109

		retval = file_permission(file, MAY_EXEC);
1110 1111
		if (retval)
			goto fput_unlock_fail;
1112 1113 1114 1115 1116

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

		fput_light(file, fput_needed);
Linus Torvalds's avatar
Linus Torvalds committed
1117 1118 1119 1120
	}
	read_unlock(&current->fs->lock);
	current->total_link_count = 0;
	retval = link_path_walk(name, nd);
1121
out:
1122 1123 1124
	if (likely(retval == 0)) {
		if (unlikely(current->audit_context && nd && nd->dentry &&
				nd->dentry->d_inode))
1125
		audit_inode(name, nd->dentry->d_inode, flags);
1126
	}
1127 1128 1129 1130 1131 1132
	return retval;

fput_unlock_fail:
	fput_light(file, fput_needed);
unlock_fail:
	read_unlock(&current->fs->lock);
Linus Torvalds's avatar
Linus Torvalds committed
1133 1134 1135
	return retval;
}

1136 1137 1138 1139 1140 1141 1142 1143 1144
int fastcall path_lookup(const char *name, unsigned int flags,
			struct nameidata *nd)
{
	return do_path_lookup(AT_FDCWD, name, flags, nd);
}

static int __path_lookup_intent_open(int dfd, const char *name,
		unsigned int lookup_flags, struct nameidata *nd,
		int open_flags, int create_mode)
1145 1146 1147 1148 1149 1150 1151 1152 1153
{
	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;
1154
	err = do_path_lookup(dfd, name, lookup_flags|LOOKUP_OPEN, nd);
1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166
	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
1167
 * @dfd: the directory to use as base, or AT_FDCWD
1168 1169 1170 1171 1172
 * @name: pointer to file name
 * @lookup_flags: lookup intent flags
 * @nd: pointer to nameidata
 * @open_flags: open intent flags
 */
1173
int path_lookup_open(int dfd, const char *name, unsigned int lookup_flags,
1174 1175
		struct nameidata *nd, int open_flags)
{
1176
	return __path_lookup_intent_open(dfd, name, lookup_flags, nd,
1177 1178 1179 1180 1181
			open_flags, 0);
}

/**
 * path_lookup_create - lookup a file path with open + create intent
1182
 * @dfd: the directory to use as base, or AT_FDCWD
1183 1184 1185 1186 1187 1188
 * @name: pointer to file name
 * @lookup_flags: lookup intent flags
 * @nd: pointer to nameidata
 * @open_flags: open intent flags
 * @create_mode: create intent flags
 */
1189 1190 1191
static int path_lookup_create(int dfd, const char *name,
			      unsigned int lookup_flags, struct nameidata *nd,
			      int open_flags, int create_mode)
1192
{
1193 1194
	return __path_lookup_intent_open(dfd, name, lookup_flags|LOOKUP_CREATE,
			nd, open_flags, create_mode);
1195 1196 1197 1198 1199 1200 1201 1202 1203
}

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)) {
1204
		err = __path_lookup_intent_open(AT_FDCWD, tmp, lookup_flags, nd, open_flags, 0);
1205 1206 1207 1208 1209
		putname(tmp);
	}
	return err;
}

Linus Torvalds's avatar
Linus Torvalds committed
1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253
/*
 * Restricted form of lookup. Doesn't follow links, single-component only,
 * needs parent already locked. Doesn't follow mounts.
 * SMP-safe.
 */
static 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;

	/*
	 * 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;
}

1254
struct dentry * lookup_hash(struct nameidata *nd)
Linus Torvalds's avatar
Linus Torvalds committed
1255
{
1256
	return __lookup_hash(&nd->last, nd->dentry, nd);
Linus Torvalds's avatar
Linus Torvalds committed
1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279
}

/* SMP-safe */
struct dentry * lookup_one_len(const char * name, struct dentry * base, int len)
{
	unsigned long hash;
	struct qstr this;
	unsigned int c;

	this.name = name;
	this.len = len;
	if (!len)
		goto access;

	hash = init_name_hash();
	while (len--) {
		c = *(const unsigned char *)name++;
		if (c == '/' || c == '\0')
			goto access;
		hash = partial_name_hash(c, hash);
	}
	this.hash = end_name_hash(hash);

1280
	return __lookup_hash(&this, base, NULL);
Linus Torvalds's avatar
Linus Torvalds committed
1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295
access:
	return ERR_PTR(-EACCES);
}

/*
 *	namei()
 *
 * is used by most simple commands to get the inode of a specified name.
 * Open, link etc use their own routines, but this is enough for things
 * like 'chmod' etc.
 *
 * namei exists in two versions: namei/lnamei. The only difference is
 * that namei follows links, while lnamei does not.
 * SMP-safe
 */
1296 1297
int fastcall __user_walk_fd(int dfd, const char __user *name, unsigned flags,
			    struct nameidata *nd)
Linus Torvalds's avatar
Linus Torvalds committed
1298 1299 1300 1301 1302
{
	char *tmp = getname(name);
	int err = PTR_ERR(tmp);

	if (!IS_ERR(tmp)) {
1303
		err = do_path_lookup(dfd, tmp, flags, nd);
Linus Torvalds's avatar
Linus Torvalds committed
1304 1305 1306 1307 1308
		putname(tmp);
	}
	return err;
}

1309 1310 1311 1312 1313
int fastcall __user_walk(const char __user *name, unsigned flags, struct nameidata *nd)
{
	return __user_walk_fd(AT_FDCWD, name, flags, nd);
}

Linus Torvalds's avatar
Linus Torvalds committed
1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347
/*
 * 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().
 */
1348
static int may_delete(struct inode *dir,struct dentry *victim,int isdir)
Linus Torvalds's avatar
Linus Torvalds committed
1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420
{
	int error;

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

	BUG_ON(victim->d_parent->d_inode != dir);

	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) {
1421
		mutex_lock(&p1->d_inode->i_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
1422 1423 1424 1425 1426 1427 1428
		return NULL;
	}

	down(&p1->d_inode->i_sb->s_vfs_rename_sem);

	for (p = p1; p->d_parent != p; p = p->d_parent) {
		if (p->d_parent == p2) {
1429 1430
			mutex_lock(&p2->d_inode->i_mutex);
			mutex_lock(&p1->d_inode->i_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
1431 1432 1433 1434 1435 1436
			return p;
		}
	}

	for (p = p2; p->d_parent != p; p = p->d_parent) {
		if (p->d_parent == p1) {
1437 1438
			mutex_lock(&p1->d_inode->i_mutex);
			mutex_lock(&p2->d_inode->i_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
1439 1440 1441 1442
			return p;
		}
	}

1443 1444
	mutex_lock(&p1->d_inode->i_mutex);
	mutex_lock(&p2->d_inode->i_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
1445 1446 1447 1448 1449
	return NULL;
}

void unlock_rename(struct dentry *p1, struct dentry *p2)
{
1450
	mutex_unlock(&p1->d_inode->i_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
1451
	if (p1 != p2) {
1452
		mutex_unlock(&p2->d_inode->i_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473
		up(&p1->d_inode->i_sb->s_vfs_rename_sem);
	}
}

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);
1474
	if (!error)
1475
		fsnotify_create(dir, dentry);
Linus Torvalds's avatar
Linus Torvalds committed
1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493
	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;

1494
	error = vfs_permission(nd, acc_mode);
Linus Torvalds's avatar
Linus Torvalds committed
1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545
	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)
		if (current->fsuid != inode->i_uid && !capable(CAP_FOWNER))
			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);
			
1546
			error = do_truncate(dentry, 0, ATTR_MTIME|ATTR_CTIME, NULL);
Linus Torvalds's avatar
Linus Torvalds committed
1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571
		}
		put_write_access(inode);
		if (error)
			return error;
	} else
		if (flag & FMODE_WRITE)
			DQUOT_INIT(inode);

	return 0;
}

/*
 *	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
 */
1572 1573
int open_namei(int dfd, const char *pathname, int flag,
		int mode, struct nameidata *nd)
Linus Torvalds's avatar
Linus Torvalds committed
1574
{
1575
	int acc_mode, error;
Al Viro's avatar
Al Viro committed
1576
	struct path path;
Linus Torvalds's avatar
Linus Torvalds committed
1577 1578 1579 1580 1581
	struct dentry *dir;
	int count = 0;

	acc_mode = ACC_MODE(flag);

1582 1583 1584 1585
	/* O_TRUNC implies we need access checks for write permissions */
	if (flag & O_TRUNC)
		acc_mode |= MAY_WRITE;

Linus Torvalds's avatar
Linus Torvalds committed
1586 1587 1588 1589 1590 1591 1592 1593 1594
	/* 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)) {
1595 1596
		error = path_lookup_open(dfd, pathname, lookup_flags(flag),
					 nd, flag);
Linus Torvalds's avatar
Linus Torvalds committed
1597 1598 1599 1600 1601 1602 1603 1604
		if (error)
			return error;
		goto ok;
	}

	/*
	 * Create - we need to know the parent.
	 */
1605
	error = path_lookup_create(dfd,pathname,LOOKUP_PARENT,nd,flag,mode);
Linus Torvalds's avatar
Linus Torvalds committed
1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619
	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;
1620
	mutex_lock(&dir->d_inode->i_mutex);
1621
	path.dentry = lookup_hash(nd);
Al Viro's avatar
Al Viro committed
1622
	path.mnt = nd->mnt;
Linus Torvalds's avatar
Linus Torvalds committed
1623 1624

do_last:
Al Viro's avatar
Al Viro committed
1625 1626
	error = PTR_ERR(path.dentry);
	if (IS_ERR(path.dentry)) {
1627
		mutex_unlock(&dir->d_inode->i_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
1628 1629 1630 1631
		goto exit;
	}

	/* Negative dentry, just create the file */
Al Viro's avatar
Al Viro committed
1632
	if (!path.dentry->d_inode) {
Linus Torvalds's avatar
Linus Torvalds committed
1633 1634
		if (!IS_POSIXACL(dir->d_inode))
			mode &= ~current->fs->umask;
Al Viro's avatar
Al Viro committed
1635
		error = vfs_create(dir->d_inode, path.dentry, mode, nd);
1636
		mutex_unlock(&dir->d_inode->i_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
1637
		dput(nd->dentry);
Al Viro's avatar
Al Viro committed
1638
		nd->dentry = path.dentry;
Linus Torvalds's avatar
Linus Torvalds committed
1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649
		if (error)
			goto exit;
		/* Don't check for write permission, don't truncate */
		acc_mode = 0;
		flag &= ~O_TRUNC;
		goto ok;
	}

	/*
	 * It already exists.
	 */
1650
	mutex_unlock(&dir->d_inode->i_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
1651 1652 1653 1654 1655

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

Al Viro's avatar
Al Viro committed
1656
	if (__follow_mount(&path)) {
Linus Torvalds's avatar
Linus Torvalds committed
1657
		error = -ELOOP;
Al Viro's avatar
Al Viro committed
1658 1659
		if (flag & O_NOFOLLOW)
			goto exit_dput;
Linus Torvalds's avatar
Linus Torvalds committed
1660 1661
	}
	error = -ENOENT;
Al Viro's avatar
Al Viro committed
1662
	if (!path.dentry->d_inode)
Linus Torvalds's avatar
Linus Torvalds committed
1663
		goto exit_dput;
Al Viro's avatar
Al Viro committed
1664
	if (path.dentry->d_inode->i_op && path.dentry->d_inode->i_op->follow_link)
Linus Torvalds's avatar
Linus Torvalds committed
1665 1666
		goto do_link;

Miklos Szeredi's avatar
Miklos Szeredi committed
1667
	path_to_nameidata(&path, nd);
Linus Torvalds's avatar
Linus Torvalds committed
1668
	error = -EISDIR;
Al Viro's avatar
Al Viro committed
1669
	if (path.dentry->d_inode && S_ISDIR(path.dentry->d_inode->i_mode))
Linus Torvalds's avatar
Linus Torvalds committed
1670 1671 1672 1673 1674 1675 1676 1677
		goto exit;
ok:
	error = may_open(nd, acc_mode, flag);
	if (error)
		goto exit;
	return 0;

exit_dput:
Miklos Szeredi's avatar
Miklos Szeredi committed
1678
	dput_path(&path, nd);
Linus Torvalds's avatar
Linus Torvalds committed
1679
exit:
1680 1681
	if (!IS_ERR(nd->intent.open.file))
		release_open_intent(nd);
Linus Torvalds's avatar
Linus Torvalds committed
1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699
	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;
Al Viro's avatar
Al Viro committed
1700
	error = security_inode_follow_link(path.dentry, nd);
Linus Torvalds's avatar
Linus Torvalds committed
1701 1702
	if (error)
		goto exit_dput;
Al Viro's avatar
Al Viro committed
1703
	error = __do_follow_link(&path, nd);
Linus Torvalds's avatar
Linus Torvalds committed
1704 1705 1706
	if (error)
		return error;
	nd->flags &= ~LOOKUP_PARENT;
Al Viro's avatar
Al Viro committed
1707
	if (nd->last_type == LAST_BIND)
Linus Torvalds's avatar
Linus Torvalds committed
1708 1709 1710 1711 1712
		goto ok;
	error = -EISDIR;
	if (nd->last_type != LAST_NORM)
		goto exit;
	if (nd->last.name[nd->last.len]) {
1713
		__putname(nd->last.name);
Linus Torvalds's avatar
Linus Torvalds committed
1714 1715 1716 1717
		goto exit;
	}
	error = -ELOOP;
	if (count++==32) {
1718
		__putname(nd->last.name);
Linus Torvalds's avatar
Linus Torvalds committed
1719 1720 1721
		goto exit;
	}
	dir = nd->dentry;
1722
	mutex_lock(&dir->d_inode->i_mutex);
1723
	path.dentry = lookup_hash(nd);
Al Viro's avatar
Al Viro committed
1724
	path.mnt = nd->mnt;
1725
	__putname(nd->last.name);
Linus Torvalds's avatar
Linus Torvalds committed
1726 1727 1728 1729 1730 1731 1732 1733 1734 1735
	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.
1736
 *
1737
 * Returns with nd->dentry->d_inode->i_mutex locked.
Linus Torvalds's avatar
Linus Torvalds committed
1738 1739 1740
 */
struct dentry *lookup_create(struct nameidata *nd, int is_dir)
{
1741
	struct dentry *dentry = ERR_PTR(-EEXIST);
Linus Torvalds's avatar
Linus Torvalds committed
1742

1743
	mutex_lock(&nd->dentry->d_inode->i_mutex);
1744 1745 1746 1747
	/*
	 * Yucky last component or no last component at all?
	 * (foo/., foo/.., /////)
	 */
Linus Torvalds's avatar
Linus Torvalds committed
1748 1749 1750
	if (nd->last_type != LAST_NORM)
		goto fail;
	nd->flags &= ~LOOKUP_PARENT;
1751 1752 1753 1754

	/*
	 * Do the final lookup.
	 */
1755
	dentry = lookup_hash(nd);
Linus Torvalds's avatar
Linus Torvalds committed
1756 1757
	if (IS_ERR(dentry))
		goto fail;
1758 1759 1760 1761 1762 1763 1764

	/*
	 * 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.
	 */
Linus Torvalds's avatar
Linus Torvalds committed
1765 1766 1767 1768 1769 1770 1771 1772 1773
	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;
}
1774
EXPORT_SYMBOL_GPL(lookup_create);
Linus Torvalds's avatar
Linus Torvalds committed
1775 1776 1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791 1792 1793 1794

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);
1795
	if (!error)
1796
		fsnotify_create(dir, dentry);
Linus Torvalds's avatar
Linus Torvalds committed
1797 1798 1799
	return error;
}

1800 1801
asmlinkage long sys_mknodat(int dfd, const char __user *filename, int mode,
				unsigned dev)
Linus Torvalds's avatar
Linus Torvalds committed
1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813
{
	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);

1814
	error = do_path_lookup(dfd, tmp, LOOKUP_PARENT, &nd);
Linus Torvalds's avatar
Linus Torvalds committed
1815 1816 1817 1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841
	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);
	}
1842
	mutex_unlock(&nd.dentry->d_inode->i_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
1843 1844 1845 1846 1847 1848 1849
	path_release(&nd);
out:
	putname(tmp);

	return error;
}

1850 1851 1852 1853 1854
asmlinkage long sys_mknod(const char __user *filename, int mode, unsigned dev)
{
	return sys_mknodat(AT_FDCWD, filename, mode, dev);
}

Linus Torvalds's avatar
Linus Torvalds committed
1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871
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);
1872
	if (!error)
1873
		fsnotify_mkdir(dir, dentry);
Linus Torvalds's avatar
Linus Torvalds committed
1874 1875 1876
	return error;
}

1877
asmlinkage long sys_mkdirat(int dfd, const char __user *pathname, int mode)
Linus Torvalds's avatar
Linus Torvalds committed
1878 1879 1880 1881 1882 1883 1884 1885 1886 1887
{
	int error = 0;
	char * tmp;

	tmp = getname(pathname);
	error = PTR_ERR(tmp);
	if (!IS_ERR(tmp)) {
		struct dentry *dentry;
		struct nameidata nd;

1888
		error = do_path_lookup(dfd, tmp, LOOKUP_PARENT, &nd);
Linus Torvalds's avatar
Linus Torvalds committed
1889 1890 1891 1892 1893 1894 1895 1896 1897 1898
		if (error)
			goto out;
		dentry = lookup_create(&nd, 1);
		error = PTR_ERR(dentry);
		if (!IS_ERR(dentry)) {
			if (!IS_POSIXACL(nd.dentry->d_inode))
				mode &= ~current->fs->umask;
			error = vfs_mkdir(nd.dentry->d_inode, dentry, mode);
			dput(dentry);
		}
1899
		mutex_unlock(&nd.dentry->d_inode->i_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
1900 1901 1902 1903 1904 1905 1906 1907
		path_release(&nd);
out:
		putname(tmp);
	}

	return error;
}

1908 1909 1910 1911 1912
asmlinkage long sys_mkdir(const char __user *pathname, int mode)
{
	return sys_mkdirat(AT_FDCWD, pathname, mode);
}

Linus Torvalds's avatar
Linus Torvalds committed
1913 1914 1915 1916 1917 1918 1919 1920 1921 1922 1923 1924 1925 1926 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
/*
 * 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);
	if (atomic_read(&dentry->d_count))
		shrink_dcache_parent(dentry);
	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);

1953
	mutex_lock(&dentry->d_inode->i_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964
	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;
		}
	}
1965
	mutex_unlock(&dentry->d_inode->i_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
1966 1967 1968 1969 1970 1971 1972 1973
	if (!error) {
		d_delete(dentry);
	}
	dput(dentry);

	return error;
}

1974
static long do_rmdir(int dfd, const char __user *pathname)
Linus Torvalds's avatar
Linus Torvalds committed
1975 1976 1977 1978 1979 1980 1981 1982 1983 1984
{
	int error = 0;
	char * name;
	struct dentry *dentry;
	struct nameidata nd;

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

1985
	error = do_path_lookup(dfd, name, LOOKUP_PARENT, &nd);
Linus Torvalds's avatar
Linus Torvalds committed
1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999
	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;
	}
2000
	mutex_lock(&nd.dentry->d_inode->i_mutex);
2001
	dentry = lookup_hash(&nd);
Linus Torvalds's avatar
Linus Torvalds committed
2002 2003 2004 2005 2006
	error = PTR_ERR(dentry);
	if (!IS_ERR(dentry)) {
		error = vfs_rmdir(nd.dentry->d_inode, dentry);
		dput(dentry);
	}
2007
	mutex_unlock(&nd.dentry->d_inode->i_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
2008 2009 2010 2011 2012 2013 2014
exit1:
	path_release(&nd);
exit:
	putname(name);
	return error;
}

2015 2016 2017 2018 2019
asmlinkage long sys_rmdir(const char __user *pathname)
{
	return do_rmdir(AT_FDCWD, pathname);
}

Linus Torvalds's avatar
Linus Torvalds committed
2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031
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);

2032
	mutex_lock(&dentry->d_inode->i_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
2033 2034 2035 2036 2037 2038 2039
	if (d_mountpoint(dentry))
		error = -EBUSY;
	else {
		error = security_inode_unlink(dir, dentry);
		if (!error)
			error = dir->i_op->unlink(dir, dentry);
	}
2040
	mutex_unlock(&dentry->d_inode->i_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
2041 2042 2043

	/* We don't d_delete() NFS sillyrenamed files--they still exist. */
	if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) {
2044
		d_delete(dentry);
Linus Torvalds's avatar
Linus Torvalds committed
2045
	}
Robert Love's avatar
Robert Love committed
2046

Linus Torvalds's avatar
Linus Torvalds committed
2047 2048 2049 2050 2051
	return error;
}

/*
 * Make sure that the actual truncation of the file will occur outside its
2052
 * directory's i_mutex.  Truncate can take a long time if there is a lot of
Linus Torvalds's avatar
Linus Torvalds committed
2053 2054 2055
 * writeout happening, and we don't want to prevent access to the directory
 * while waiting on the I/O.
 */
2056
static long do_unlinkat(int dfd, const char __user *pathname)
Linus Torvalds's avatar
Linus Torvalds committed
2057 2058 2059 2060 2061 2062 2063 2064 2065 2066 2067
{
	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);

2068
	error = do_path_lookup(dfd, name, LOOKUP_PARENT, &nd);
Linus Torvalds's avatar
Linus Torvalds committed
2069 2070 2071 2072 2073
	if (error)
		goto exit;
	error = -EISDIR;
	if (nd.last_type != LAST_NORM)
		goto exit1;
2074
	mutex_lock(&nd.dentry->d_inode->i_mutex);
2075
	dentry = lookup_hash(&nd);
Linus Torvalds's avatar
Linus Torvalds committed
2076 2077 2078 2079 2080 2081 2082 2083 2084 2085 2086 2087
	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);
	}
2088
	mutex_unlock(&nd.dentry->d_inode->i_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
2089 2090 2091 2092 2093 2094 2095 2096 2097 2098 2099 2100 2101 2102
	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;
}

2103 2104 2105 2106 2107 2108 2109 2110 2111 2112 2113 2114 2115 2116 2117 2118
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);
}

Linus Torvalds's avatar
Linus Torvalds committed
2119 2120 2121 2122 2123 2124 2125 2126 2127 2128 2129 2130 2131 2132 2133 2134
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);
2135
	if (!error)
2136
		fsnotify_create(dir, dentry);
Linus Torvalds's avatar
Linus Torvalds committed
2137 2138 2139
	return error;
}

2140 2141
asmlinkage long sys_symlinkat(const char __user *oldname,
			      int newdfd, const char __user *newname)
Linus Torvalds's avatar
Linus Torvalds committed
2142 2143 2144 2145 2146 2147 2148 2149 2150 2151 2152 2153 2154 2155
{
	int error = 0;
	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)) {
		struct dentry *dentry;
		struct nameidata nd;

2156
		error = do_path_lookup(newdfd, to, LOOKUP_PARENT, &nd);
Linus Torvalds's avatar
Linus Torvalds committed
2157 2158 2159 2160 2161 2162 2163 2164
		if (error)
			goto out;
		dentry = lookup_create(&nd, 0);
		error = PTR_ERR(dentry);
		if (!IS_ERR(dentry)) {
			error = vfs_symlink(nd.dentry->d_inode, dentry, from, S_IALLUGO);
			dput(dentry);
		}
2165
		mutex_unlock(&nd.dentry->d_inode->i_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
2166 2167 2168 2169 2170 2171 2172 2173
		path_release(&nd);
out:
		putname(to);
	}
	putname(from);
	return error;
}

2174 2175 2176 2177 2178
asmlinkage long sys_symlink(const char __user *oldname, const char __user *newname)
{
	return sys_symlinkat(oldname, AT_FDCWD, newname);
}

Linus Torvalds's avatar
Linus Torvalds committed
2179 2180 2181 2182 2183 2184 2185 2186 2187 2188 2189 2190 2191 2192 2193 2194 2195 2196 2197 2198 2199 2200 2201 2202 2203 2204 2205 2206 2207
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;

2208
	mutex_lock(&old_dentry->d_inode->i_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
2209 2210
	DQUOT_INIT(dir);
	error = dir->i_op->link(old_dentry, dir, new_dentry);
2211
	mutex_unlock(&old_dentry->d_inode->i_mutex);
2212
	if (!error)
2213
		fsnotify_create(dir, new_dentry);
Linus Torvalds's avatar
Linus Torvalds committed
2214 2215 2216 2217 2218 2219 2220 2221 2222 2223 2224 2225
	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
 */
2226
asmlinkage long sys_linkat(int olddfd, const char __user *oldname,
2227 2228
			   int newdfd, const char __user *newname,
			   int flags)
Linus Torvalds's avatar
Linus Torvalds committed
2229 2230 2231 2232 2233 2234
{
	struct dentry *new_dentry;
	struct nameidata nd, old_nd;
	int error;
	char * to;

2235 2236 2237
	if (flags != 0)
		return -EINVAL;

Linus Torvalds's avatar
Linus Torvalds committed
2238 2239 2240 2241
	to = getname(newname);
	if (IS_ERR(to))
		return PTR_ERR(to);

2242
	error = __user_walk_fd(olddfd, oldname, 0, &old_nd);
Linus Torvalds's avatar
Linus Torvalds committed
2243 2244
	if (error)
		goto exit;
2245
	error = do_path_lookup(newdfd, to, LOOKUP_PARENT, &nd);
Linus Torvalds's avatar
Linus Torvalds committed
2246 2247 2248 2249 2250 2251 2252 2253 2254 2255 2256
	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);
	if (!IS_ERR(new_dentry)) {
		error = vfs_link(old_nd.dentry, nd.dentry->d_inode, new_dentry);
		dput(new_dentry);
	}
2257
	mutex_unlock(&nd.dentry->d_inode->i_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
2258 2259 2260 2261 2262 2263 2264 2265 2266 2267
out_release:
	path_release(&nd);
out:
	path_release(&old_nd);
exit:
	putname(to);

	return error;
}

2268 2269
asmlinkage long sys_link(const char __user *oldname, const char __user *newname)
{
2270
	return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0);
2271 2272
}

Linus Torvalds's avatar
Linus Torvalds committed
2273 2274 2275 2276 2277 2278 2279 2280 2281 2282
/*
 * 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
 *	   sb->s_vfs_rename_sem. We might be more accurate, but that's another
 *	   story.
 *	c) we have to lock _three_ objects - parents and victim (if it exists).
2283
 *	   And that - after we got ->i_mutex on parents (until then we don't know
Linus Torvalds's avatar
Linus Torvalds committed
2284 2285 2286 2287 2288 2289 2290 2291 2292 2293 2294 2295 2296 2297 2298 2299
 *	   whether the target exists).  Solution: try to be smart with locking
 *	   order for inodes.  We rely on the fact that tree topology may change
 *	   only under ->s_vfs_rename_sem _and_ that parent of the object we
 *	   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,
 *	   lock child" and rename is under ->s_vfs_rename_sem.
 *	   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
2300
 *	   we are removing the target. Solution: we will have to grab ->i_mutex
Linus Torvalds's avatar
Linus Torvalds committed
2301
 *	   in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
2302
 *	   ->i_mutex on parents, which works but leads to some truely excessive
Linus Torvalds's avatar
Linus Torvalds committed
2303 2304
 *	   locking].
 */
2305 2306
static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry,
			  struct inode *new_dir, struct dentry *new_dentry)
Linus Torvalds's avatar
Linus Torvalds committed
2307 2308 2309 2310 2311 2312 2313 2314 2315 2316 2317 2318 2319 2320 2321 2322 2323 2324 2325 2326
{
	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) {
2327
		mutex_lock(&target->i_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
2328 2329 2330 2331 2332 2333 2334 2335 2336
		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;
2337
		mutex_unlock(&target->i_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
2338 2339 2340 2341
		if (d_unhashed(new_dentry))
			d_rehash(new_dentry);
		dput(new_dentry);
	}
2342
	if (!error)
Linus Torvalds's avatar
Linus Torvalds committed
2343 2344 2345 2346
		d_move(old_dentry,new_dentry);
	return error;
}

2347 2348
static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry,
			    struct inode *new_dir, struct dentry *new_dentry)
Linus Torvalds's avatar
Linus Torvalds committed
2349 2350 2351 2352 2353 2354 2355 2356 2357 2358 2359
{
	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)
2360
		mutex_lock(&target->i_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
2361 2362 2363 2364 2365 2366 2367 2368 2369 2370
	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) {
		/* The following d_move() should become unconditional */
		if (!(old_dir->i_sb->s_type->fs_flags & FS_ODD_RENAME))
			d_move(old_dentry, new_dentry);
	}
	if (target)
2371
		mutex_unlock(&target->i_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
2372 2373 2374 2375 2376 2377 2378 2379 2380
	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);
Robert Love's avatar
Robert Love committed
2381
	const char *old_name;
Linus Torvalds's avatar
Linus Torvalds committed
2382 2383 2384 2385 2386 2387 2388 2389 2390 2391 2392 2393 2394 2395 2396 2397 2398 2399 2400 2401 2402

	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);

Robert Love's avatar
Robert Love committed
2403 2404
	old_name = fsnotify_oldname_init(old_dentry->d_name.name);

Linus Torvalds's avatar
Linus Torvalds committed
2405 2406 2407 2408 2409
	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) {
Robert Love's avatar
Robert Love committed
2410
		const char *new_name = old_dentry->d_name.name;
2411 2412
		fsnotify_move(old_dir, new_dir, old_name, new_name, is_dir,
			      new_dentry->d_inode, old_dentry->d_inode);
Linus Torvalds's avatar
Linus Torvalds committed
2413
	}
Robert Love's avatar
Robert Love committed
2414 2415
	fsnotify_oldname_free(old_name);

Linus Torvalds's avatar
Linus Torvalds committed
2416 2417 2418
	return error;
}

2419 2420
static int do_rename(int olddfd, const char *oldname,
			int newdfd, const char *newname)
Linus Torvalds's avatar
Linus Torvalds committed
2421 2422 2423 2424 2425 2426 2427
{
	int error = 0;
	struct dentry * old_dir, * new_dir;
	struct dentry * old_dentry, *new_dentry;
	struct dentry * trap;
	struct nameidata oldnd, newnd;

2428
	error = do_path_lookup(olddfd, oldname, LOOKUP_PARENT, &oldnd);
Linus Torvalds's avatar
Linus Torvalds committed
2429 2430 2431
	if (error)
		goto exit;

2432
	error = do_path_lookup(newdfd, newname, LOOKUP_PARENT, &newnd);
Linus Torvalds's avatar
Linus Torvalds committed
2433 2434 2435 2436 2437 2438 2439 2440 2441 2442 2443 2444 2445 2446 2447 2448 2449 2450
	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);

2451
	old_dentry = lookup_hash(&oldnd);
Linus Torvalds's avatar
Linus Torvalds committed
2452 2453 2454 2455 2456 2457 2458 2459 2460 2461 2462 2463 2464 2465 2466 2467 2468 2469 2470
	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;
2471
	new_dentry = lookup_hash(&newnd);
Linus Torvalds's avatar
Linus Torvalds committed
2472 2473 2474 2475 2476 2477 2478 2479 2480 2481 2482 2483 2484 2485 2486 2487 2488 2489 2490 2491 2492 2493 2494 2495
	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;
}

2496 2497
asmlinkage long sys_renameat(int olddfd, const char __user *oldname,
			     int newdfd, const char __user *newname)
Linus Torvalds's avatar
Linus Torvalds committed
2498 2499 2500 2501 2502 2503 2504 2505 2506 2507 2508
{
	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)) {
2509
		error = do_rename(olddfd, from, newdfd, to);
Linus Torvalds's avatar
Linus Torvalds committed
2510 2511 2512 2513 2514 2515
		putname(to);
	}
	putname(from);
	return error;
}

2516 2517 2518 2519 2520
asmlinkage long sys_rename(const char __user *oldname, const char __user *newname)
{
	return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname);
}

Linus Torvalds's avatar
Linus Torvalds committed
2521 2522 2523 2524 2525 2526 2527 2528 2529 2530 2531 2532 2533 2534 2535 2536 2537 2538 2539 2540 2541 2542 2543 2544 2545
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;
2546 2547
	void *cookie;

Linus Torvalds's avatar
Linus Torvalds committed
2548
	nd.depth = 0;
2549 2550 2551
	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));
Linus Torvalds's avatar
Linus Torvalds committed
2552
		if (dentry->d_inode->i_op->put_link)
2553 2554
			dentry->d_inode->i_op->put_link(dentry, &nd, cookie);
		cookie = ERR_PTR(res);
Linus Torvalds's avatar
Linus Torvalds committed
2555
	}
2556
	return PTR_ERR(cookie);
Linus Torvalds's avatar
Linus Torvalds committed
2557 2558 2559 2560 2561 2562 2563 2564 2565 2566 2567 2568 2569 2570 2571 2572 2573 2574 2575 2576 2577 2578 2579 2580 2581 2582 2583 2584 2585 2586 2587 2588 2589 2590 2591 2592 2593 2594 2595 2596 2597 2598
}

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;
	page = read_cache_page(mapping, 0, (filler_t *)mapping->a_ops->readpage,
				NULL);
	if (IS_ERR(page))
		goto sync_fail;
	wait_on_page_locked(page);
	if (!PageUptodate(page))
		goto async_fail;
	*ppage = page;
	return kmap(page);

async_fail:
	page_cache_release(page);
	return ERR_PTR(-EIO);

sync_fail:
	return (char*)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;
}

2599
void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd)
Linus Torvalds's avatar
Linus Torvalds committed
2600
{
2601
	struct page *page = NULL;
Linus Torvalds's avatar
Linus Torvalds committed
2602
	nd_set_link(nd, page_getlink(dentry, &page));
2603
	return page;
Linus Torvalds's avatar
Linus Torvalds committed
2604 2605
}

2606
void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
Linus Torvalds's avatar
Linus Torvalds committed
2607
{
2608 2609 2610
	struct page *page = cookie;

	if (page) {
Linus Torvalds's avatar
Linus Torvalds committed
2611 2612 2613 2614 2615
		kunmap(page);
		page_cache_release(page);
	}
}

2616 2617
int __page_symlink(struct inode *inode, const char *symname, int len,
		gfp_t gfp_mask)
Linus Torvalds's avatar
Linus Torvalds committed
2618 2619
{
	struct address_space *mapping = inode->i_mapping;
2620
	struct page *page;
Linus Torvalds's avatar
Linus Torvalds committed
2621 2622 2623
	int err = -ENOMEM;
	char *kaddr;

2624
	page = find_or_create_page(mapping, 0, gfp_mask);
Linus Torvalds's avatar
Linus Torvalds committed
2625 2626 2627 2628 2629 2630 2631 2632 2633 2634 2635 2636 2637 2638 2639 2640 2641 2642 2643 2644 2645 2646 2647 2648 2649 2650 2651 2652 2653 2654 2655 2656 2657 2658
	if (!page)
		goto fail;
	err = mapping->a_ops->prepare_write(NULL, page, 0, len-1);
	if (err)
		goto fail_map;
	kaddr = kmap_atomic(page, KM_USER0);
	memcpy(kaddr, symname, len-1);
	kunmap_atomic(kaddr, KM_USER0);
	mapping->a_ops->commit_write(NULL, page, 0, len-1);
	/*
	 * 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);
		wait_on_page_locked(page);
	} 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;
}

2659 2660 2661 2662 2663 2664
int page_symlink(struct inode *inode, const char *symname, int len)
{
	return __page_symlink(inode, symname, len,
			mapping_gfp_mask(inode->i_mapping));
}

Linus Torvalds's avatar
Linus Torvalds committed
2665 2666 2667 2668 2669 2670 2671
struct inode_operations page_symlink_inode_operations = {
	.readlink	= generic_readlink,
	.follow_link	= page_follow_link_light,
	.put_link	= page_put_link,
};

EXPORT_SYMBOL(__user_walk);
2672
EXPORT_SYMBOL(__user_walk_fd);
Linus Torvalds's avatar
Linus Torvalds committed
2673 2674 2675 2676 2677 2678 2679 2680 2681 2682
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_hash);
EXPORT_SYMBOL(lookup_one_len);
EXPORT_SYMBOL(page_follow_link_light);
EXPORT_SYMBOL(page_put_link);
EXPORT_SYMBOL(page_readlink);
2683
EXPORT_SYMBOL(__page_symlink);
Linus Torvalds's avatar
Linus Torvalds committed
2684 2685 2686 2687 2688 2689
EXPORT_SYMBOL(page_symlink);
EXPORT_SYMBOL(page_symlink_inode_operations);
EXPORT_SYMBOL(path_lookup);
EXPORT_SYMBOL(path_release);
EXPORT_SYMBOL(path_walk);
EXPORT_SYMBOL(permission);
2690
EXPORT_SYMBOL(vfs_permission);
2691
EXPORT_SYMBOL(file_permission);
Linus Torvalds's avatar
Linus Torvalds committed
2692 2693 2694 2695 2696 2697 2698 2699 2700 2701 2702 2703 2704 2705
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);