namei.c 68.9 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
#include <linux/fcntl.h>
L
Linus Torvalds 已提交
33 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
#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)
105
 * implemented.  Let's see if raised priority of ->s_vfs_rename_mutex gives
L
Linus Torvalds 已提交
106 107 108
 * any extra contention...
 */

109 110
static int fastcall link_path_walk(const char *name, struct nameidata *nd);

L
Linus Torvalds 已提交
111 112 113 114 115 116 117
/* 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)
L
Linus Torvalds 已提交
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
{
	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)
{
162
	if (unlikely(!audit_dummy_context()))
L
Linus Torvalds 已提交
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
		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;
231 232 233 234
	struct vfsmount *mnt = NULL;

	if (nd)
		mnt = nd->mnt;
L
Linus Torvalds 已提交
235 236

	if (mask & MAY_WRITE) {
237
		umode_t mode = inode->i_mode;
L
Linus Torvalds 已提交
238 239 240 241 242 243 244 245 246 247 248 249 250 251 252

		/*
		 * 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;
	}

253 254 255 256 257
	if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode)) {
		/*
		 * MAY_EXEC on regular files is denied if the fs is mounted
		 * with the "noexec" flag.
		 */
258
		if (mnt && (mnt->mnt_flags & MNT_NOEXEC))
259 260
			return -EACCES;
	}
261

L
Linus Torvalds 已提交
262 263
	/* Ordinary permission routines do not understand MAY_APPEND. */
	submask = mask & ~MAY_APPEND;
264
	if (inode->i_op && inode->i_op->permission) {
L
Linus Torvalds 已提交
265
		retval = inode->i_op->permission(inode, submask, nd);
266 267 268 269 270 271 272 273 274 275 276 277 278
		if (!retval) {
			/*
			 * Exec permission on a regular file is denied if none
			 * of the execute bits are set.
			 *
			 * This check should be done by the ->permission()
			 * method.
			 */
			if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode) &&
			    !(inode->i_mode & S_IXUGO))
				return -EACCES;
		}
	} else {
L
Linus Torvalds 已提交
279
		retval = generic_permission(inode, submask, NULL);
280
	}
L
Linus Torvalds 已提交
281 282 283 284 285 286
	if (retval)
		return retval;

	return security_inode_permission(inode, mask, nd);
}

287 288 289 290 291 292 293 294 295 296 297 298 299 300 301
/**
 * 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);
}

302 303 304 305 306 307 308 309 310 311 312 313 314 315
/**
 * 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)
{
316
	return permission(file->f_path.dentry->d_inode, mask, NULL);
317 318
}

L
Linus Torvalds 已提交
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
/*
 * 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)
{
352
	struct inode *inode = file->f_path.dentry->d_inode;
L
Linus Torvalds 已提交
353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377

	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);
378
	mntput_no_expire(nd->mnt);
L
Linus Torvalds 已提交
379 380
}

381 382 383 384 385 386
/**
 * release_open_intent - free up open intent resources
 * @nd: pointer to nameidata
 */
void release_open_intent(struct nameidata *nd)
{
387
	if (nd->intent.open.file->f_path.dentry == NULL)
388 389 390 391 392
		put_filp(nd->intent.open.file);
	else
		fput(nd->intent.open.file);
}

393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416
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
417 418 419 420 421 422 423 424 425 426 427 428 429 430
/*
 * 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);

431 432 433
	if (dentry && dentry->d_op && dentry->d_op->d_revalidate)
		dentry = do_revalidate(dentry, nd);

L
Linus Torvalds 已提交
434 435 436 437 438 439 440 441 442 443 444 445 446
	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.
 */
447
static int exec_permission_lite(struct inode *inode,
L
Linus Torvalds 已提交
448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489
				       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;

490
	mutex_lock(&dir->i_mutex);
L
Linus Torvalds 已提交
491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515
	/*
	 * 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;
		}
516
		mutex_unlock(&dir->i_mutex);
L
Linus Torvalds 已提交
517 518 519 520 521 522 523
		return result;
	}

	/*
	 * Uhhuh! Nasty case: the cache was re-populated while
	 * we waited on the semaphore. Need to revalidate.
	 */
524
	mutex_unlock(&dir->i_mutex);
L
Linus Torvalds 已提交
525
	if (result->d_op && result->d_op->d_revalidate) {
526 527
		result = do_revalidate(result, nd);
		if (!result)
L
Linus Torvalds 已提交
528 529 530 531 532 533 534 535
			result = ERR_PTR(-ENOENT);
	}
	return result;
}

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

/* SMP-safe */
536
static __always_inline int
L
Linus Torvalds 已提交
537 538
walk_init_root(const char *name, struct nameidata *nd)
{
539 540 541 542 543 544 545
	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
546 547
		if (__emul_lookup_dentry(name,nd))
			return 0;
548
		read_lock(&fs->lock);
L
Linus Torvalds 已提交
549
	}
550 551 552
	nd->mnt = mntget(fs->rootmnt);
	nd->dentry = dget(fs->root);
	read_unlock(&fs->lock);
L
Linus Torvalds 已提交
553 554 555
	return 1;
}

556
static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link)
L
Linus Torvalds 已提交
557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590
{
	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);
}

591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606
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;
}

607
static __always_inline int __do_follow_link(struct path *path, struct nameidata *nd)
L
Linus Torvalds 已提交
608 609
{
	int error;
610
	void *cookie;
A
Al Viro 已提交
611
	struct dentry *dentry = path->dentry;
L
Linus Torvalds 已提交
612

A
Al Viro 已提交
613
	touch_atime(path->mnt, dentry);
L
Linus Torvalds 已提交
614
	nd_set_link(nd, NULL);
A
Al Viro 已提交
615

616 617 618 619 620
	if (path->mnt != nd->mnt) {
		path_to_nameidata(path, nd);
		dget(dentry);
	}
	mntget(path->mnt);
621 622 623
	cookie = dentry->d_inode->i_op->follow_link(dentry, nd);
	error = PTR_ERR(cookie);
	if (!IS_ERR(cookie)) {
L
Linus Torvalds 已提交
624
		char *s = nd_get_link(nd);
625
		error = 0;
L
Linus Torvalds 已提交
626 627 628
		if (s)
			error = __vfs_follow_link(nd, s);
		if (dentry->d_inode->i_op->put_link)
629
			dentry->d_inode->i_op->put_link(dentry, nd, cookie);
L
Linus Torvalds 已提交
630
	}
A
Al Viro 已提交
631 632
	dput(dentry);
	mntput(path->mnt);
L
Linus Torvalds 已提交
633 634 635 636 637 638 639 640 641 642 643

	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
644
static inline int do_follow_link(struct path *path, struct nameidata *nd)
L
Linus Torvalds 已提交
645 646 647 648 649 650 651 652
{
	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
653
	err = security_inode_follow_link(path->dentry, nd);
L
Linus Torvalds 已提交
654 655 656 657 658
	if (err)
		goto loop;
	current->link_count++;
	current->total_link_count++;
	nd->depth++;
A
Al Viro 已提交
659
	err = __do_follow_link(path, nd);
A
Al Viro 已提交
660 661
	current->link_count--;
	nd->depth--;
L
Linus Torvalds 已提交
662 663
	return err;
loop:
M
Miklos Szeredi 已提交
664
	dput_path(path, nd);
A
Al Viro 已提交
665
	path_release(nd);
L
Linus Torvalds 已提交
666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691
	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
692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708
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
709
static void follow_mount(struct vfsmount **mnt, struct dentry **dentry)
L
Linus Torvalds 已提交
710 711 712 713 714
{
	while (d_mountpoint(*dentry)) {
		struct vfsmount *mounted = lookup_mnt(*mnt, *dentry);
		if (!mounted)
			break;
A
Al Viro 已提交
715
		dput(*dentry);
L
Linus Torvalds 已提交
716 717 718 719 720 721 722 723 724
		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
725
int follow_down(struct vfsmount **mnt, struct dentry **dentry)
L
Linus Torvalds 已提交
726 727 728 729 730
{
	struct vfsmount *mounted;

	mounted = lookup_mnt(*mnt, *dentry);
	if (mounted) {
A
Al Viro 已提交
731
		dput(*dentry);
L
Linus Torvalds 已提交
732 733 734 735 736 737 738 739
		mntput(*mnt);
		*mnt = mounted;
		*dentry = dget(mounted->mnt_root);
		return 1;
	}
	return 0;
}

740
static __always_inline void follow_dotdot(struct nameidata *nd)
L
Linus Torvalds 已提交
741
{
742 743
	struct fs_struct *fs = current->fs;

L
Linus Torvalds 已提交
744 745
	while(1) {
		struct vfsmount *parent;
A
Al Viro 已提交
746
		struct dentry *old = nd->dentry;
L
Linus Torvalds 已提交
747

748 749 750 751
                read_lock(&fs->lock);
		if (nd->dentry == fs->root &&
		    nd->mnt == fs->rootmnt) {
                        read_unlock(&fs->lock);
L
Linus Torvalds 已提交
752 753
			break;
		}
754
                read_unlock(&fs->lock);
L
Linus Torvalds 已提交
755
		spin_lock(&dcache_lock);
A
Al Viro 已提交
756 757
		if (nd->dentry != nd->mnt->mnt_root) {
			nd->dentry = dget(nd->dentry->d_parent);
L
Linus Torvalds 已提交
758 759 760 761 762 763
			spin_unlock(&dcache_lock);
			dput(old);
			break;
		}
		spin_unlock(&dcache_lock);
		spin_lock(&vfsmount_lock);
A
Al Viro 已提交
764 765
		parent = nd->mnt->mnt_parent;
		if (parent == nd->mnt) {
L
Linus Torvalds 已提交
766 767 768 769
			spin_unlock(&vfsmount_lock);
			break;
		}
		mntget(parent);
A
Al Viro 已提交
770
		nd->dentry = dget(nd->mnt->mnt_mountpoint);
L
Linus Torvalds 已提交
771 772
		spin_unlock(&vfsmount_lock);
		dput(old);
A
Al Viro 已提交
773 774
		mntput(nd->mnt);
		nd->mnt = parent;
L
Linus Torvalds 已提交
775
	}
A
Al Viro 已提交
776
	follow_mount(&nd->mnt, &nd->dentry);
L
Linus Torvalds 已提交
777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796
}

/*
 *  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
797
	__follow_mount(path);
L
Linus Torvalds 已提交
798 799 800 801 802 803 804 805 806
	return 0;

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

need_revalidate:
807 808 809 810 811 812
	dentry = do_revalidate(dentry, nd);
	if (!dentry)
		goto need_lookup;
	if (IS_ERR(dentry))
		goto fail;
	goto done;
L
Linus Torvalds 已提交
813 814 815 816 817 818 819

fail:
	return PTR_ERR(dentry);
}

/*
 * Name resolution.
820 821
 * 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
822
 *
823 824
 * 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
825 826 827 828 829 830 831 832 833 834 835 836 837 838 839
 */
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)
840
		lookup_flags = LOOKUP_FOLLOW | (nd->flags & LOOKUP_CONTINUE);
L
Linus Torvalds 已提交
841 842 843 844 845 846 847

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

848
		nd->flags |= LOOKUP_CONTINUE;
L
Linus Torvalds 已提交
849
		err = exec_permission_lite(inode, nd);
850 851
		if (err == -EAGAIN)
			err = vfs_permission(nd, MAY_EXEC);
L
Linus Torvalds 已提交
852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884
 		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
885
				follow_dotdot(nd);
L
Linus Torvalds 已提交
886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913
				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
914
			err = do_follow_link(&next, nd);
L
Linus Torvalds 已提交
915 916 917 918 919 920 921 922 923
			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
924 925
		} else
			path_to_nameidata(&next, nd);
L
Linus Torvalds 已提交
926 927 928 929 930 931 932 933 934
		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:
935 936
		/* Clear LOOKUP_CONTINUE iff it was previously unset */
		nd->flags &= lookup_flags | ~LOOKUP_CONTINUE;
L
Linus Torvalds 已提交
937 938 939 940 941 942 943 944
		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
945
				follow_dotdot(nd);
L
Linus Torvalds 已提交
946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961
				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
962
			err = do_follow_link(&next, nd);
L
Linus Torvalds 已提交
963 964 965
			if (err)
				goto return_err;
			inode = nd->dentry->d_inode;
M
Miklos Szeredi 已提交
966 967
		} else
			path_to_nameidata(&next, nd);
L
Linus Torvalds 已提交
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 1001 1002
		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
1003
		dput_path(&next, nd);
L
Linus Torvalds 已提交
1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017
		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.
 */
1018
static int fastcall link_path_walk(const char *name, struct nameidata *nd)
L
Linus Torvalds 已提交
1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041
{
	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;
}

J
Josef 'Jeff' Sipek 已提交
1042
static int fastcall path_walk(const char * name, struct nameidata *nd)
L
Linus Torvalds 已提交
1043 1044 1045 1046 1047
{
	current->total_link_count = 0;
	return link_path_walk(name, nd);
}

1048 1049 1050 1051
/* 
 * 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
1052 1053 1054 1055 1056 1057 1058 1059 1060 1061
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;
1062 1063
		struct fs_struct *fs = current->fs;

L
Linus Torvalds 已提交
1064
		/*
1065 1066
		 * 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
1067 1068
		 */
		nd->last_type = LAST_ROOT;
1069 1070 1071 1072
		read_lock(&fs->lock);
		nd->mnt = mntget(fs->rootmnt);
		nd->dentry = dget(fs->root);
		read_unlock(&fs->lock);
L
Linus Torvalds 已提交
1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095
		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;
1096
	struct fs_struct *fs = current->fs;
L
Linus Torvalds 已提交
1097 1098 1099 1100 1101 1102 1103 1104 1105

	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:
1106 1107 1108 1109 1110 1111
	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
1112 1113 1114 1115 1116 1117
	if (olddentry) {
		dput(olddentry);
		mntput(oldmnt);
	}
}

1118
/* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
1119 1120
static int fastcall do_path_lookup(int dfd, const char *name,
				unsigned int flags, struct nameidata *nd)
L
Linus Torvalds 已提交
1121
{
1122
	int retval = 0;
1123 1124
	int fput_needed;
	struct file *file;
1125
	struct fs_struct *fs = current->fs;
L
Linus Torvalds 已提交
1126 1127 1128 1129 1130 1131

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

	if (*name=='/') {
1132 1133 1134 1135 1136
		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
1137
			if (__emul_lookup_dentry(name,nd))
1138
				goto out; /* found in altroot */
1139
			read_lock(&fs->lock);
L
Linus Torvalds 已提交
1140
		}
1141 1142 1143
		nd->mnt = mntget(fs->rootmnt);
		nd->dentry = dget(fs->root);
		read_unlock(&fs->lock);
1144
	} else if (dfd == AT_FDCWD) {
1145 1146 1147 1148
		read_lock(&fs->lock);
		nd->mnt = mntget(fs->pwdmnt);
		nd->dentry = dget(fs->pwd);
		read_unlock(&fs->lock);
1149 1150 1151 1152
	} else {
		struct dentry *dentry;

		file = fget_light(dfd, &fput_needed);
1153 1154
		retval = -EBADF;
		if (!file)
1155
			goto out_fail;
1156

1157
		dentry = file->f_path.dentry;
1158

1159 1160
		retval = -ENOTDIR;
		if (!S_ISDIR(dentry->d_inode->i_mode))
1161
			goto fput_fail;
1162 1163

		retval = file_permission(file, MAY_EXEC);
1164
		if (retval)
1165
			goto fput_fail;
1166

1167
		nd->mnt = mntget(file->f_path.mnt);
1168 1169 1170
		nd->dentry = dget(dentry);

		fput_light(file, fput_needed);
L
Linus Torvalds 已提交
1171
	}
1172 1173

	retval = path_walk(name, nd);
1174
out:
1175
	if (unlikely(!retval && !audit_dummy_context() && nd->dentry &&
1176
				nd->dentry->d_inode))
1177
		audit_inode(name, nd->dentry);
1178
out_fail:
1179 1180
	return retval;

1181
fput_fail:
1182
	fput_light(file, fput_needed);
1183
	goto out_fail;
L
Linus Torvalds 已提交
1184 1185
}

1186 1187 1188 1189 1190 1191
int fastcall path_lookup(const char *name, unsigned int flags,
			struct nameidata *nd)
{
	return do_path_lookup(AT_FDCWD, name, flags, nd);
}

1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216
/**
 * 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))
1217
		audit_inode(name, nd->dentry);
1218 1219 1220 1221 1222

	return retval;

}

1223 1224 1225
static int __path_lookup_intent_open(int dfd, const char *name,
		unsigned int lookup_flags, struct nameidata *nd,
		int open_flags, int create_mode)
1226 1227 1228 1229 1230 1231 1232 1233 1234
{
	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;
1235
	err = do_path_lookup(dfd, name, lookup_flags|LOOKUP_OPEN, nd);
1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247
	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
1248
 * @dfd: the directory to use as base, or AT_FDCWD
1249 1250 1251 1252 1253
 * @name: pointer to file name
 * @lookup_flags: lookup intent flags
 * @nd: pointer to nameidata
 * @open_flags: open intent flags
 */
1254
int path_lookup_open(int dfd, const char *name, unsigned int lookup_flags,
1255 1256
		struct nameidata *nd, int open_flags)
{
1257
	return __path_lookup_intent_open(dfd, name, lookup_flags, nd,
1258 1259 1260 1261 1262
			open_flags, 0);
}

/**
 * path_lookup_create - lookup a file path with open + create intent
1263
 * @dfd: the directory to use as base, or AT_FDCWD
1264 1265 1266 1267 1268 1269
 * @name: pointer to file name
 * @lookup_flags: lookup intent flags
 * @nd: pointer to nameidata
 * @open_flags: open intent flags
 * @create_mode: create intent flags
 */
1270 1271 1272
static int path_lookup_create(int dfd, const char *name,
			      unsigned int lookup_flags, struct nameidata *nd,
			      int open_flags, int create_mode)
1273
{
1274 1275
	return __path_lookup_intent_open(dfd, name, lookup_flags|LOOKUP_CREATE,
			nd, open_flags, create_mode);
1276 1277 1278 1279 1280 1281 1282 1283 1284
}

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)) {
1285
		err = __path_lookup_intent_open(AT_FDCWD, tmp, lookup_flags, nd, open_flags, 0);
1286 1287 1288 1289 1290
		putname(tmp);
	}
	return err;
}

1291 1292
static struct dentry *__lookup_hash(struct qstr *name,
		struct dentry *base, struct nameidata *nd)
L
Linus Torvalds 已提交
1293
{
1294
	struct dentry *dentry;
L
Linus Torvalds 已提交
1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326
	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;
}

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.
 */
1332
static struct dentry *lookup_hash(struct nameidata *nd)
1333 1334 1335
{
	int err;

1336
	err = permission(nd->dentry->d_inode, MAY_EXEC, nd);
1337
	if (err)
1338
		return ERR_PTR(err);
1339
	return __lookup_hash(&nd->last, nd->dentry, nd);
L
Linus Torvalds 已提交
1340 1341
}

1342 1343
static int __lookup_one_len(const char *name, struct qstr *this,
		struct dentry *base, int len)
L
Linus Torvalds 已提交
1344 1345 1346 1347
{
	unsigned long hash;
	unsigned int c;

1348 1349
	this->name = name;
	this->len = len;
L
Linus Torvalds 已提交
1350
	if (!len)
1351
		return -EACCES;
L
Linus Torvalds 已提交
1352 1353 1354 1355 1356

	hash = init_name_hash();
	while (len--) {
		c = *(const unsigned char *)name++;
		if (c == '/' || c == '\0')
1357
			return -EACCES;
L
Linus Torvalds 已提交
1358 1359
		hash = partial_name_hash(c, hash);
	}
1360 1361 1362
	this->hash = end_name_hash(hash);
	return 0;
}
L
Linus Torvalds 已提交
1363

1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374
/**
 * lookup_one_len:  filesystem helper to lookup single pathname component
 * @name:	pathname component to lookup
 * @base:	base directory to lookup from
 * @len:	maximum length @len should be interpreted to
 *
 * Note that this routine is purely a helper for filesystem useage and should
 * not be called by generic code.  Also note that by using this function to
 * nameidata argument is passed to the filesystem methods and a filesystem
 * using this helper needs to be prepared for that.
 */
1375 1376 1377 1378 1379 1380
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);
1381 1382 1383 1384
	if (err)
		return ERR_PTR(err);

	err = permission(base->d_inode, MAY_EXEC, NULL);
1385 1386
	if (err)
		return ERR_PTR(err);
1387
	return __lookup_hash(&this, base, NULL);
1388 1389
}

1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401
/**
 * lookup_one_noperm - bad hack for sysfs
 * @name:	pathname component to lookup
 * @base:	base directory to lookup from
 *
 * This is a variant of lookup_one_len that doesn't perform any permission
 * checks.   It's a horrible hack to work around the braindead sysfs
 * architecture and should not be used anywhere else.
 *
 * DON'T USE THIS FUNCTION EVER, thanks.
 */
struct dentry *lookup_one_noperm(const char *name, struct dentry *base)
1402 1403 1404 1405
{
	int err;
	struct qstr this;

1406
	err = __lookup_one_len(name, &this, base, strlen(name));
1407 1408
	if (err)
		return ERR_PTR(err);
1409
	return __lookup_hash(&this, base, NULL);
L
Linus Torvalds 已提交
1410 1411
}

1412 1413
int fastcall __user_walk_fd(int dfd, const char __user *name, unsigned flags,
			    struct nameidata *nd)
L
Linus Torvalds 已提交
1414 1415 1416 1417 1418
{
	char *tmp = getname(name);
	int err = PTR_ERR(tmp);

	if (!IS_ERR(tmp)) {
1419
		err = do_path_lookup(dfd, tmp, flags, nd);
L
Linus Torvalds 已提交
1420 1421 1422 1423 1424
		putname(tmp);
	}
	return err;
}

1425 1426 1427 1428 1429
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
1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463
/*
 * 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().
 */
1464
static int may_delete(struct inode *dir,struct dentry *victim,int isdir)
L
Linus Torvalds 已提交
1465 1466 1467 1468 1469 1470 1471
{
	int error;

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

	BUG_ON(victim->d_parent->d_inode != dir);
1472
	audit_inode_child(victim->d_name.name, victim, dir);
L
Linus Torvalds 已提交
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 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

	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
1538
		mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
L
Linus Torvalds 已提交
1539 1540 1541
		return NULL;
	}

1542
	mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex);
L
Linus Torvalds 已提交
1543 1544 1545

	for (p = p1; p->d_parent != p; p = p->d_parent) {
		if (p->d_parent == p2) {
I
Ingo Molnar 已提交
1546 1547
			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
1548 1549 1550 1551 1552 1553
			return p;
		}
	}

	for (p = p2; p->d_parent != p; p = p->d_parent) {
		if (p->d_parent == p1) {
I
Ingo Molnar 已提交
1554 1555
			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
1556 1557 1558 1559
			return p;
		}
	}

I
Ingo Molnar 已提交
1560 1561
	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
1562 1563 1564 1565 1566
	return NULL;
}

void unlock_rename(struct dentry *p1, struct dentry *p2)
{
1567
	mutex_unlock(&p1->d_inode->i_mutex);
L
Linus Torvalds 已提交
1568
	if (p1 != p2) {
1569
		mutex_unlock(&p2->d_inode->i_mutex);
1570
		mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex);
L
Linus Torvalds 已提交
1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590
	}
}

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);
1591
	if (!error)
1592
		fsnotify_create(dir, dentry);
L
Linus Torvalds 已提交
1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624
	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;

	/*
	 * 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;
1625 1626 1627 1628

	error = vfs_permission(nd, acc_mode);
	if (error)
		return error;
L
Linus Torvalds 已提交
1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640
	/*
	 * 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)
1641
		if (!is_owner_or_cap(inode))
L
Linus Torvalds 已提交
1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661
			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);
1662 1663 1664 1665

			error = do_truncate(dentry, 0,
					    ATTR_MTIME|ATTR_CTIME|ATTR_OPEN,
					    NULL);
L
Linus Torvalds 已提交
1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676
		}
		put_write_access(inode);
		if (error)
			return error;
	} else
		if (flag & FMODE_WRITE)
			DQUOT_INIT(inode);

	return 0;
}

1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694
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
1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708
/*
 *	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
 */
1709 1710
int open_namei(int dfd, const char *pathname, int flag,
		int mode, struct nameidata *nd)
L
Linus Torvalds 已提交
1711
{
1712
	int acc_mode, error;
A
Al Viro 已提交
1713
	struct path path;
L
Linus Torvalds 已提交
1714 1715 1716 1717 1718
	struct dentry *dir;
	int count = 0;

	acc_mode = ACC_MODE(flag);

1719 1720 1721 1722
	/* O_TRUNC implies we need access checks for write permissions */
	if (flag & O_TRUNC)
		acc_mode |= MAY_WRITE;

L
Linus Torvalds 已提交
1723 1724 1725 1726 1727 1728 1729 1730 1731
	/* 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)) {
1732 1733
		error = path_lookup_open(dfd, pathname, lookup_flags(flag),
					 nd, flag);
L
Linus Torvalds 已提交
1734 1735 1736 1737 1738 1739 1740 1741
		if (error)
			return error;
		goto ok;
	}

	/*
	 * Create - we need to know the parent.
	 */
1742
	error = path_lookup_create(dfd,pathname,LOOKUP_PARENT,nd,flag,mode);
L
Linus Torvalds 已提交
1743 1744 1745 1746 1747 1748 1749 1750 1751 1752 1753 1754 1755 1756
	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;
1757
	mutex_lock(&dir->d_inode->i_mutex);
1758
	path.dentry = lookup_hash(nd);
A
Al Viro 已提交
1759
	path.mnt = nd->mnt;
L
Linus Torvalds 已提交
1760 1761

do_last:
A
Al Viro 已提交
1762 1763
	error = PTR_ERR(path.dentry);
	if (IS_ERR(path.dentry)) {
1764
		mutex_unlock(&dir->d_inode->i_mutex);
L
Linus Torvalds 已提交
1765 1766 1767
		goto exit;
	}

1768 1769 1770 1771 1772 1773
	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
1774
	/* Negative dentry, just create the file */
A
Al Viro 已提交
1775
	if (!path.dentry->d_inode) {
1776
		error = open_namei_create(nd, &path, flag, mode);
L
Linus Torvalds 已提交
1777 1778
		if (error)
			goto exit;
1779
		return 0;
L
Linus Torvalds 已提交
1780 1781 1782 1783 1784
	}

	/*
	 * It already exists.
	 */
1785
	mutex_unlock(&dir->d_inode->i_mutex);
1786
	audit_inode(pathname, path.dentry);
L
Linus Torvalds 已提交
1787 1788 1789 1790 1791

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

A
Al Viro 已提交
1792
	if (__follow_mount(&path)) {
L
Linus Torvalds 已提交
1793
		error = -ELOOP;
A
Al Viro 已提交
1794 1795
		if (flag & O_NOFOLLOW)
			goto exit_dput;
L
Linus Torvalds 已提交
1796
	}
1797

L
Linus Torvalds 已提交
1798
	error = -ENOENT;
A
Al Viro 已提交
1799
	if (!path.dentry->d_inode)
L
Linus Torvalds 已提交
1800
		goto exit_dput;
A
Al Viro 已提交
1801
	if (path.dentry->d_inode->i_op && path.dentry->d_inode->i_op->follow_link)
L
Linus Torvalds 已提交
1802 1803
		goto do_link;

M
Miklos Szeredi 已提交
1804
	path_to_nameidata(&path, nd);
L
Linus Torvalds 已提交
1805
	error = -EISDIR;
A
Al Viro 已提交
1806
	if (path.dentry->d_inode && S_ISDIR(path.dentry->d_inode->i_mode))
L
Linus Torvalds 已提交
1807 1808 1809 1810 1811 1812 1813 1814
		goto exit;
ok:
	error = may_open(nd, acc_mode, flag);
	if (error)
		goto exit;
	return 0;

exit_dput:
M
Miklos Szeredi 已提交
1815
	dput_path(&path, nd);
L
Linus Torvalds 已提交
1816
exit:
1817 1818
	if (!IS_ERR(nd->intent.open.file))
		release_open_intent(nd);
L
Linus Torvalds 已提交
1819 1820 1821 1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836
	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
1837
	error = security_inode_follow_link(path.dentry, nd);
L
Linus Torvalds 已提交
1838 1839
	if (error)
		goto exit_dput;
A
Al Viro 已提交
1840
	error = __do_follow_link(&path, nd);
K
Kirill Korotaev 已提交
1841 1842 1843 1844 1845 1846
	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
1847
		return error;
K
Kirill Korotaev 已提交
1848
	}
L
Linus Torvalds 已提交
1849
	nd->flags &= ~LOOKUP_PARENT;
A
Al Viro 已提交
1850
	if (nd->last_type == LAST_BIND)
L
Linus Torvalds 已提交
1851 1852 1853 1854 1855
		goto ok;
	error = -EISDIR;
	if (nd->last_type != LAST_NORM)
		goto exit;
	if (nd->last.name[nd->last.len]) {
1856
		__putname(nd->last.name);
L
Linus Torvalds 已提交
1857 1858 1859 1860
		goto exit;
	}
	error = -ELOOP;
	if (count++==32) {
1861
		__putname(nd->last.name);
L
Linus Torvalds 已提交
1862 1863 1864
		goto exit;
	}
	dir = nd->dentry;
1865
	mutex_lock(&dir->d_inode->i_mutex);
1866
	path.dentry = lookup_hash(nd);
A
Al Viro 已提交
1867
	path.mnt = nd->mnt;
1868
	__putname(nd->last.name);
L
Linus Torvalds 已提交
1869 1870 1871 1872 1873 1874 1875 1876 1877 1878
	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.
1879
 *
1880
 * Returns with nd->dentry->d_inode->i_mutex locked.
L
Linus Torvalds 已提交
1881 1882 1883
 */
struct dentry *lookup_create(struct nameidata *nd, int is_dir)
{
1884
	struct dentry *dentry = ERR_PTR(-EEXIST);
L
Linus Torvalds 已提交
1885

I
Ingo Molnar 已提交
1886
	mutex_lock_nested(&nd->dentry->d_inode->i_mutex, I_MUTEX_PARENT);
1887 1888 1889 1890
	/*
	 * Yucky last component or no last component at all?
	 * (foo/., foo/.., /////)
	 */
L
Linus Torvalds 已提交
1891 1892 1893
	if (nd->last_type != LAST_NORM)
		goto fail;
	nd->flags &= ~LOOKUP_PARENT;
1894 1895
	nd->flags |= LOOKUP_CREATE;
	nd->intent.open.flags = O_EXCL;
1896 1897 1898 1899

	/*
	 * Do the final lookup.
	 */
1900
	dentry = lookup_hash(nd);
L
Linus Torvalds 已提交
1901 1902
	if (IS_ERR(dentry))
		goto fail;
1903 1904 1905 1906 1907 1908 1909

	/*
	 * 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
1910 1911 1912 1913 1914 1915 1916 1917 1918
	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;
}
1919
EXPORT_SYMBOL_GPL(lookup_create);
L
Linus Torvalds 已提交
1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939

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);
1940
	if (!error)
1941
		fsnotify_create(dir, dentry);
L
Linus Torvalds 已提交
1942 1943 1944
	return error;
}

1945 1946
asmlinkage long sys_mknodat(int dfd, const char __user *filename, int mode,
				unsigned dev)
L
Linus Torvalds 已提交
1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958
{
	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);

1959
	error = do_path_lookup(dfd, tmp, LOOKUP_PARENT, &nd);
L
Linus Torvalds 已提交
1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986
	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);
	}
1987
	mutex_unlock(&nd.dentry->d_inode->i_mutex);
L
Linus Torvalds 已提交
1988 1989 1990 1991 1992 1993 1994
	path_release(&nd);
out:
	putname(tmp);

	return error;
}

1995 1996 1997 1998 1999
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
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016
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);
2017
	if (!error)
2018
		fsnotify_mkdir(dir, dentry);
L
Linus Torvalds 已提交
2019 2020 2021
	return error;
}

2022
asmlinkage long sys_mkdirat(int dfd, const char __user *pathname, int mode)
L
Linus Torvalds 已提交
2023 2024 2025
{
	int error = 0;
	char * tmp;
2026 2027
	struct dentry *dentry;
	struct nameidata nd;
L
Linus Torvalds 已提交
2028 2029 2030

	tmp = getname(pathname);
	error = PTR_ERR(tmp);
2031 2032
	if (IS_ERR(tmp))
		goto out_err;
L
Linus Torvalds 已提交
2033

2034 2035 2036 2037 2038 2039 2040
	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
2041

2042 2043 2044 2045 2046 2047 2048 2049 2050 2051
	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
2052 2053 2054
	return error;
}

2055 2056 2057 2058 2059
asmlinkage long sys_mkdir(const char __user *pathname, int mode)
{
	return sys_mkdirat(AT_FDCWD, pathname, mode);
}

L
Linus Torvalds 已提交
2060 2061 2062 2063 2064 2065 2066 2067 2068 2069 2070 2071 2072 2073 2074 2075 2076 2077
/*
 * 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);
2078
	shrink_dcache_parent(dentry);
L
Linus Torvalds 已提交
2079 2080 2081 2082 2083 2084 2085 2086 2087 2088 2089 2090 2091 2092 2093 2094 2095 2096 2097 2098
	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);

2099
	mutex_lock(&dentry->d_inode->i_mutex);
L
Linus Torvalds 已提交
2100 2101 2102 2103 2104 2105 2106 2107 2108 2109 2110
	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;
		}
	}
2111
	mutex_unlock(&dentry->d_inode->i_mutex);
L
Linus Torvalds 已提交
2112 2113 2114 2115 2116 2117 2118 2119
	if (!error) {
		d_delete(dentry);
	}
	dput(dentry);

	return error;
}

2120
static long do_rmdir(int dfd, const char __user *pathname)
L
Linus Torvalds 已提交
2121 2122 2123 2124 2125 2126 2127 2128 2129 2130
{
	int error = 0;
	char * name;
	struct dentry *dentry;
	struct nameidata nd;

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

2131
	error = do_path_lookup(dfd, name, LOOKUP_PARENT, &nd);
L
Linus Torvalds 已提交
2132 2133 2134 2135 2136 2137 2138 2139 2140 2141 2142 2143 2144 2145
	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
2146
	mutex_lock_nested(&nd.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
2147
	dentry = lookup_hash(&nd);
L
Linus Torvalds 已提交
2148
	error = PTR_ERR(dentry);
2149 2150 2151 2152 2153
	if (IS_ERR(dentry))
		goto exit2;
	error = vfs_rmdir(nd.dentry->d_inode, dentry);
	dput(dentry);
exit2:
2154
	mutex_unlock(&nd.dentry->d_inode->i_mutex);
L
Linus Torvalds 已提交
2155 2156 2157 2158 2159 2160 2161
exit1:
	path_release(&nd);
exit:
	putname(name);
	return error;
}

2162 2163 2164 2165 2166
asmlinkage long sys_rmdir(const char __user *pathname)
{
	return do_rmdir(AT_FDCWD, pathname);
}

L
Linus Torvalds 已提交
2167 2168 2169 2170 2171 2172 2173 2174 2175 2176 2177 2178
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);

2179
	mutex_lock(&dentry->d_inode->i_mutex);
L
Linus Torvalds 已提交
2180 2181 2182 2183 2184 2185 2186
	if (d_mountpoint(dentry))
		error = -EBUSY;
	else {
		error = security_inode_unlink(dir, dentry);
		if (!error)
			error = dir->i_op->unlink(dir, dentry);
	}
2187
	mutex_unlock(&dentry->d_inode->i_mutex);
L
Linus Torvalds 已提交
2188 2189 2190

	/* 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
2191
		d_delete(dentry);
L
Linus Torvalds 已提交
2192
	}
R
Robert Love 已提交
2193

L
Linus Torvalds 已提交
2194 2195 2196 2197 2198
	return error;
}

/*
 * Make sure that the actual truncation of the file will occur outside its
2199
 * directory's i_mutex.  Truncate can take a long time if there is a lot of
L
Linus Torvalds 已提交
2200 2201 2202
 * writeout happening, and we don't want to prevent access to the directory
 * while waiting on the I/O.
 */
2203
static long do_unlinkat(int dfd, const char __user *pathname)
L
Linus Torvalds 已提交
2204 2205 2206 2207 2208 2209 2210 2211 2212 2213 2214
{
	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);

2215
	error = do_path_lookup(dfd, name, LOOKUP_PARENT, &nd);
L
Linus Torvalds 已提交
2216 2217 2218 2219 2220
	if (error)
		goto exit;
	error = -EISDIR;
	if (nd.last_type != LAST_NORM)
		goto exit1;
I
Ingo Molnar 已提交
2221
	mutex_lock_nested(&nd.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
2222
	dentry = lookup_hash(&nd);
L
Linus Torvalds 已提交
2223 2224 2225 2226 2227 2228 2229 2230 2231 2232 2233 2234
	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);
	}
2235
	mutex_unlock(&nd.dentry->d_inode->i_mutex);
L
Linus Torvalds 已提交
2236 2237 2238 2239 2240 2241 2242 2243 2244 2245 2246 2247 2248 2249
	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;
}

2250 2251 2252 2253 2254 2255 2256 2257 2258 2259 2260 2261 2262 2263 2264 2265
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
2266 2267 2268 2269 2270 2271 2272 2273 2274 2275 2276 2277 2278 2279 2280 2281
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);
2282
	if (!error)
2283
		fsnotify_create(dir, dentry);
L
Linus Torvalds 已提交
2284 2285 2286
	return error;
}

2287 2288
asmlinkage long sys_symlinkat(const char __user *oldname,
			      int newdfd, const char __user *newname)
L
Linus Torvalds 已提交
2289 2290 2291 2292
{
	int error = 0;
	char * from;
	char * to;
2293 2294
	struct dentry *dentry;
	struct nameidata nd;
L
Linus Torvalds 已提交
2295 2296 2297 2298 2299 2300

	from = getname(oldname);
	if(IS_ERR(from))
		return PTR_ERR(from);
	to = getname(newname);
	error = PTR_ERR(to);
2301 2302
	if (IS_ERR(to))
		goto out_putname;
L
Linus Torvalds 已提交
2303

2304 2305 2306 2307 2308 2309 2310 2311 2312 2313 2314 2315 2316
	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
2317
out:
2318 2319
	putname(to);
out_putname:
L
Linus Torvalds 已提交
2320 2321 2322 2323
	putname(from);
	return error;
}

2324 2325 2326 2327 2328
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
2329 2330 2331 2332 2333 2334 2335 2336 2337 2338 2339 2340 2341 2342 2343 2344 2345 2346 2347 2348 2349 2350 2351 2352 2353 2354 2355 2356 2357
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;

2358
	mutex_lock(&old_dentry->d_inode->i_mutex);
L
Linus Torvalds 已提交
2359 2360
	DQUOT_INIT(dir);
	error = dir->i_op->link(old_dentry, dir, new_dentry);
2361
	mutex_unlock(&old_dentry->d_inode->i_mutex);
2362
	if (!error)
2363
		fsnotify_create(dir, new_dentry);
L
Linus Torvalds 已提交
2364 2365 2366 2367 2368 2369 2370 2371 2372 2373 2374 2375
	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
 */
2376
asmlinkage long sys_linkat(int olddfd, const char __user *oldname,
2377 2378
			   int newdfd, const char __user *newname,
			   int flags)
L
Linus Torvalds 已提交
2379 2380 2381 2382 2383 2384
{
	struct dentry *new_dentry;
	struct nameidata nd, old_nd;
	int error;
	char * to;

2385
	if ((flags & ~AT_SYMLINK_FOLLOW) != 0)
2386 2387
		return -EINVAL;

L
Linus Torvalds 已提交
2388 2389 2390 2391
	to = getname(newname);
	if (IS_ERR(to))
		return PTR_ERR(to);

2392 2393 2394
	error = __user_walk_fd(olddfd, oldname,
			       flags & AT_SYMLINK_FOLLOW ? LOOKUP_FOLLOW : 0,
			       &old_nd);
L
Linus Torvalds 已提交
2395 2396
	if (error)
		goto exit;
2397
	error = do_path_lookup(newdfd, to, LOOKUP_PARENT, &nd);
L
Linus Torvalds 已提交
2398 2399 2400 2401 2402 2403 2404
	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);
2405 2406 2407 2408 2409
	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:
2410
	mutex_unlock(&nd.dentry->d_inode->i_mutex);
L
Linus Torvalds 已提交
2411 2412 2413 2414 2415 2416 2417 2418 2419 2420
out_release:
	path_release(&nd);
out:
	path_release(&old_nd);
exit:
	putname(to);

	return error;
}

2421 2422
asmlinkage long sys_link(const char __user *oldname, const char __user *newname)
{
2423
	return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0);
2424 2425
}

L
Linus Torvalds 已提交
2426 2427 2428 2429 2430 2431 2432
/*
 * 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
2433
 *	   sb->s_vfs_rename_mutex. We might be more accurate, but that's another
L
Linus Torvalds 已提交
2434 2435
 *	   story.
 *	c) we have to lock _three_ objects - parents and victim (if it exists).
2436
 *	   And that - after we got ->i_mutex on parents (until then we don't know
L
Linus Torvalds 已提交
2437 2438
 *	   whether the target exists).  Solution: try to be smart with locking
 *	   order for inodes.  We rely on the fact that tree topology may change
2439
 *	   only under ->s_vfs_rename_mutex _and_ that parent of the object we
L
Linus Torvalds 已提交
2440 2441 2442
 *	   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,
2443
 *	   lock child" and rename is under ->s_vfs_rename_mutex.
L
Linus Torvalds 已提交
2444 2445 2446 2447 2448 2449 2450 2451 2452
 *	   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
2453
 *	   we are removing the target. Solution: we will have to grab ->i_mutex
L
Linus Torvalds 已提交
2454
 *	   in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
2455
 *	   ->i_mutex on parents, which works but leads to some truely excessive
L
Linus Torvalds 已提交
2456 2457
 *	   locking].
 */
A
Adrian Bunk 已提交
2458 2459
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
2460 2461 2462 2463 2464 2465 2466 2467 2468 2469 2470 2471 2472 2473 2474 2475 2476 2477 2478 2479
{
	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) {
2480
		mutex_lock(&target->i_mutex);
L
Linus Torvalds 已提交
2481 2482 2483 2484 2485 2486 2487 2488 2489
		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;
2490
		mutex_unlock(&target->i_mutex);
L
Linus Torvalds 已提交
2491 2492 2493 2494
		if (d_unhashed(new_dentry))
			d_rehash(new_dentry);
		dput(new_dentry);
	}
2495
	if (!error)
2496 2497
		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
2498 2499 2500
	return error;
}

A
Adrian Bunk 已提交
2501 2502
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
2503 2504 2505 2506 2507 2508 2509 2510 2511 2512 2513
{
	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)
2514
		mutex_lock(&target->i_mutex);
L
Linus Torvalds 已提交
2515 2516 2517 2518 2519
	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) {
2520
		if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE))
L
Linus Torvalds 已提交
2521 2522 2523
			d_move(old_dentry, new_dentry);
	}
	if (target)
2524
		mutex_unlock(&target->i_mutex);
L
Linus Torvalds 已提交
2525 2526 2527 2528 2529 2530 2531 2532 2533
	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
2534
	const char *old_name;
L
Linus Torvalds 已提交
2535 2536 2537 2538 2539 2540 2541 2542 2543 2544 2545 2546 2547 2548 2549 2550 2551 2552 2553 2554 2555

	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
2556 2557
	old_name = fsnotify_oldname_init(old_dentry->d_name.name);

L
Linus Torvalds 已提交
2558 2559 2560 2561 2562
	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
2563
		const char *new_name = old_dentry->d_name.name;
2564
		fsnotify_move(old_dir, new_dir, old_name, new_name, is_dir,
2565
			      new_dentry->d_inode, old_dentry);
L
Linus Torvalds 已提交
2566
	}
R
Robert Love 已提交
2567 2568
	fsnotify_oldname_free(old_name);

L
Linus Torvalds 已提交
2569 2570 2571
	return error;
}

2572 2573
static int do_rename(int olddfd, const char *oldname,
			int newdfd, const char *newname)
L
Linus Torvalds 已提交
2574 2575 2576 2577 2578 2579 2580
{
	int error = 0;
	struct dentry * old_dir, * new_dir;
	struct dentry * old_dentry, *new_dentry;
	struct dentry * trap;
	struct nameidata oldnd, newnd;

2581
	error = do_path_lookup(olddfd, oldname, LOOKUP_PARENT, &oldnd);
L
Linus Torvalds 已提交
2582 2583 2584
	if (error)
		goto exit;

2585
	error = do_path_lookup(newdfd, newname, LOOKUP_PARENT, &newnd);
L
Linus Torvalds 已提交
2586 2587 2588 2589 2590 2591 2592 2593 2594 2595 2596 2597 2598 2599 2600 2601 2602 2603
	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);

2604
	old_dentry = lookup_hash(&oldnd);
L
Linus Torvalds 已提交
2605 2606 2607 2608 2609 2610 2611 2612 2613 2614 2615 2616 2617 2618 2619 2620 2621 2622 2623
	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;
2624
	new_dentry = lookup_hash(&newnd);
L
Linus Torvalds 已提交
2625 2626 2627 2628 2629 2630 2631 2632 2633 2634 2635 2636 2637 2638 2639 2640 2641 2642 2643 2644 2645 2646 2647 2648
	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;
}

2649 2650
asmlinkage long sys_renameat(int olddfd, const char __user *oldname,
			     int newdfd, const char __user *newname)
L
Linus Torvalds 已提交
2651 2652 2653 2654 2655 2656 2657 2658 2659 2660 2661
{
	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)) {
2662
		error = do_rename(olddfd, from, newdfd, to);
L
Linus Torvalds 已提交
2663 2664 2665 2666 2667 2668
		putname(to);
	}
	putname(from);
	return error;
}

2669 2670 2671 2672 2673
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
2674 2675 2676 2677 2678 2679 2680 2681 2682 2683 2684 2685 2686 2687 2688 2689 2690 2691 2692 2693 2694 2695 2696 2697 2698
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;
2699 2700
	void *cookie;

L
Linus Torvalds 已提交
2701
	nd.depth = 0;
2702 2703 2704
	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
2705
		if (dentry->d_inode->i_op->put_link)
2706 2707
			dentry->d_inode->i_op->put_link(dentry, &nd, cookie);
		cookie = ERR_PTR(res);
L
Linus Torvalds 已提交
2708
	}
2709
	return PTR_ERR(cookie);
L
Linus Torvalds 已提交
2710 2711 2712 2713 2714 2715 2716 2717 2718 2719 2720 2721
}

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;
2722
	page = read_mapping_page(mapping, 0, NULL);
L
Linus Torvalds 已提交
2723
	if (IS_ERR(page))
2724
		return (char*)page;
L
Linus Torvalds 已提交
2725 2726 2727 2728 2729 2730 2731 2732 2733 2734 2735 2736 2737 2738 2739 2740
	*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;
}

2741
void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd)
L
Linus Torvalds 已提交
2742
{
2743
	struct page *page = NULL;
L
Linus Torvalds 已提交
2744
	nd_set_link(nd, page_getlink(dentry, &page));
2745
	return page;
L
Linus Torvalds 已提交
2746 2747
}

2748
void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
L
Linus Torvalds 已提交
2749
{
2750 2751 2752
	struct page *page = cookie;

	if (page) {
L
Linus Torvalds 已提交
2753 2754 2755 2756 2757
		kunmap(page);
		page_cache_release(page);
	}
}

2758 2759
int __page_symlink(struct inode *inode, const char *symname, int len,
		gfp_t gfp_mask)
L
Linus Torvalds 已提交
2760 2761
{
	struct address_space *mapping = inode->i_mapping;
2762
	struct page *page;
2763
	void *fsdata;
2764
	int err;
L
Linus Torvalds 已提交
2765 2766
	char *kaddr;

2767
retry:
2768 2769
	err = pagecache_write_begin(NULL, mapping, 0, len-1,
				AOP_FLAG_UNINTERRUPTIBLE, &page, &fsdata);
L
Linus Torvalds 已提交
2770
	if (err)
2771 2772
		goto fail;

L
Linus Torvalds 已提交
2773 2774 2775
	kaddr = kmap_atomic(page, KM_USER0);
	memcpy(kaddr, symname, len-1);
	kunmap_atomic(kaddr, KM_USER0);
2776 2777 2778

	err = pagecache_write_end(NULL, mapping, 0, len-1, len-1,
							page, fsdata);
L
Linus Torvalds 已提交
2779 2780
	if (err < 0)
		goto fail;
2781 2782 2783
	if (err < len-1)
		goto retry;

L
Linus Torvalds 已提交
2784 2785 2786 2787 2788 2789
	mark_inode_dirty(inode);
	return 0;
fail:
	return err;
}

2790 2791 2792 2793 2794 2795
int page_symlink(struct inode *inode, const char *symname, int len)
{
	return __page_symlink(inode, symname, len,
			mapping_gfp_mask(inode->i_mapping));
}

2796
const struct inode_operations page_symlink_inode_operations = {
L
Linus Torvalds 已提交
2797 2798 2799 2800 2801 2802
	.readlink	= generic_readlink,
	.follow_link	= page_follow_link_light,
	.put_link	= page_put_link,
};

EXPORT_SYMBOL(__user_walk);
2803
EXPORT_SYMBOL(__user_walk_fd);
L
Linus Torvalds 已提交
2804 2805 2806 2807 2808 2809 2810 2811 2812
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);
2813
EXPORT_SYMBOL(__page_symlink);
L
Linus Torvalds 已提交
2814 2815 2816
EXPORT_SYMBOL(page_symlink);
EXPORT_SYMBOL(page_symlink_inode_operations);
EXPORT_SYMBOL(path_lookup);
2817
EXPORT_SYMBOL(vfs_path_lookup);
L
Linus Torvalds 已提交
2818 2819
EXPORT_SYMBOL(path_release);
EXPORT_SYMBOL(permission);
2820
EXPORT_SYMBOL(vfs_permission);
2821
EXPORT_SYMBOL(file_permission);
L
Linus Torvalds 已提交
2822 2823 2824 2825 2826 2827 2828 2829 2830 2831 2832 2833 2834 2835
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);