Release 4.13 fs/namei.c

/*
 *  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/export.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/namei.h>
#include <linux/pagemap.h>
#include <linux/fsnotify.h>
#include <linux/personality.h>
#include <linux/security.h>
#include <linux/ima.h>
#include <linux/syscalls.h>
#include <linux/mount.h>
#include <linux/audit.h>
#include <linux/capability.h>
#include <linux/file.h>
#include <linux/fcntl.h>
#include <linux/device_cgroup.h>
#include <linux/fs_struct.h>
#include <linux/posix_acl.h>
#include <linux/hash.h>
#include <linux/bitops.h>
#include <linux/init_task.h>
#include <linux/uaccess.h>

#include "internal.h"
#include "mount.h"

/* [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-existent 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_mutex 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.
 */


#define EMBEDDED_NAME_MAX	(PATH_MAX - offsetof(struct filename, iname))


struct filename *

getname_flags(const char __user *filename, int flags, int *empty)
{
	struct filename *result;
	char *kname;
	int len;

	result = audit_reusename(filename);
	if (result)
		return result;

	result = __getname();
	if (unlikely(!result))
		return ERR_PTR(-ENOMEM);

	/*
         * First, try to embed the struct filename inside the names_cache
         * allocation
         */
	kname = (char *)result->iname;
	result->name = kname;

	len = strncpy_from_user(kname, filename, EMBEDDED_NAME_MAX);
	if (unlikely(len < 0)) {
		__putname(result);
		return ERR_PTR(len);
	}

	/*
         * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a
         * separate struct filename so we can dedicate the entire
         * names_cache allocation for the pathname, and re-do the copy from
         * userland.
         */
	if (unlikely(len == EMBEDDED_NAME_MAX)) {
		const size_t size = offsetof(struct filename, iname[1]);
		kname = (char *)result;

		/*
                 * size is chosen that way we to guarantee that
                 * result->iname[0] is within the same object and that
                 * kname can't be equal to result->iname, no matter what.
                 */
		result = kzalloc(size, GFP_KERNEL);
		if (unlikely(!result)) {
			__putname(kname);
			return ERR_PTR(-ENOMEM);
		}
		result->name = kname;
		len = strncpy_from_user(kname, filename, PATH_MAX);
		if (unlikely(len < 0)) {
			__putname(kname);
			kfree(result);
			return ERR_PTR(len);
		}
		if (unlikely(len == PATH_MAX)) {
			__putname(kname);
			kfree(result);
			return ERR_PTR(-ENAMETOOLONG);
		}
	}

	result->refcnt = 1;
	/* The empty path is special. */
	if (unlikely(!len)) {
		if (empty)
			*empty = 1;
		if (!(flags & LOOKUP_EMPTY)) {
			putname(result);
			return ERR_PTR(-ENOENT);
		}
	}

	result->uptr = filename;
	result->aname = NULL;
	audit_getname(result);
	return result;
}

Contributors
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CommitProp
Al Viro
133
41.05%
3
17.65%
Jeff Layton
103
31.79%
3
17.65%
Linus Torvalds
33
10.19%
3
17.65%
Linus Torvalds (pre-git)
26
8.02%
4
23.53%
Eric Paris
11
3.40%
1
5.88%
Andy Whitcroft
11
3.40%
1
5.88%
Paul Moore
6
1.85%
1
5.88%
Chris Wright
1
0.31%
1
5.88%
Total
324
100.00%
17
100.00%


struct filename *

getname(const char __user * filename)
{
	return getname_flags(filename, 0, NULL);
}

Contributors
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CommitProp
Al Viro
19
82.61%
1
25.00%
Jeff Layton
2
8.70%
1
25.00%
Andy Whitcroft
1
4.35%
1
25.00%
Linus Torvalds
1
4.35%
1
25.00%
Total
23
100.00%
4
100.00%


struct filename *

getname_kernel(const char * filename)
{
	struct filename *result;
	int len = strlen(filename) + 1;

	result = __getname();
	if (unlikely(!result))
		return ERR_PTR(-ENOMEM);

	if (len <= EMBEDDED_NAME_MAX) {
		result->name = (char *)result->iname;
	} else if (len <= PATH_MAX) {
		struct filename *tmp;

		tmp = kmalloc(sizeof(*tmp), GFP_KERNEL);
		if (unlikely(!tmp)) {
			__putname(result);
			return ERR_PTR(-ENOMEM);
		}
		tmp->name = (char *)result;
		result = tmp;
	} else {
		__putname(result);
		return ERR_PTR(-ENAMETOOLONG);
	}
	memcpy((char *)result->name, filename, len);
	result->uptr = NULL;
	result->aname = NULL;
	result->refcnt = 1;
	audit_getname(result);

	return result;
}

Contributors
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CommitProp
Paul Moore
118
63.44%
3
60.00%
Linus Torvalds
67
36.02%
1
20.00%
Al Viro
1
0.54%
1
20.00%
Total
186
100.00%
5
100.00%



void putname(struct filename *name)
{
	BUG_ON(name->refcnt <= 0);

	if (--name->refcnt > 0)
		return;

	if (name->name != name->iname) {
		__putname(name->name);
		kfree(name);
	} else
		__putname(name);
}

Contributors
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CommitProp
Paul Moore
33
55.93%
1
16.67%
Chris Wright
9
15.25%
1
16.67%
Andrew Morton
9
15.25%
1
16.67%
Al Viro
5
8.47%
1
16.67%
Jeff Layton
2
3.39%
1
16.67%
Linus Torvalds (pre-git)
1
1.69%
1
16.67%
Total
59
100.00%
6
100.00%



static int check_acl(struct inode *inode, int mask)
{
#ifdef CONFIG_FS_POSIX_ACL
	struct posix_acl *acl;

	if (mask & MAY_NOT_BLOCK) {
		acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS);
	        if (!acl)
	                return -EAGAIN;
		/* no ->get_acl() calls in RCU mode... */
		if (is_uncached_acl(acl))
			return -ECHILD;
	        return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK);
	}

	acl = get_acl(inode, ACL_TYPE_ACCESS);
	if (IS_ERR(acl))
		return PTR_ERR(acl);
	if (acl) {
	        int error = posix_acl_permission(inode, acl, mask);
	        posix_acl_release(acl);
	        return error;
	}
#endif

	return -EAGAIN;
}

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Linus Torvalds
71
55.91%
3
27.27%
Al Viro
25
19.69%
2
18.18%
Christoph Hellwig
16
12.60%
2
18.18%
Linus Torvalds (pre-git)
9
7.09%
2
18.18%
Andreas Gruenbacher
3
2.36%
1
9.09%
Ari Savolainen
3
2.36%
1
9.09%
Total
127
100.00%
11
100.00%

/*
 * This does the basic permission checking
 */


static int acl_permission_check(struct inode *inode, int mask)
{
	unsigned int mode = inode->i_mode;

	if (likely(uid_eq(current_fsuid(), inode->i_uid)))
		mode >>= 6;
	else {
		if (IS_POSIXACL(inode) && (mode & S_IRWXG)) {
			int error = check_acl(inode, mask);
			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 ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0)
		return 0;
	return -EACCES;
}

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CommitProp
Christoph Hellwig
48
40.34%
1
7.14%
Linus Torvalds (pre-git)
34
28.57%
3
21.43%
Linus Torvalds
19
15.97%
5
35.71%
Al Viro
11
9.24%
2
14.29%
Eric W. Biedermann
4
3.36%
1
7.14%
David Howells
2
1.68%
1
7.14%
Nicholas Piggin
1
0.84%
1
7.14%
Total
119
100.00%
14
100.00%

/**
 * 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, ...)
 *
 * 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.
 *
 * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk
 * request cannot be satisfied (eg. requires blocking or too much complexity).
 * It would then be called again in ref-walk mode.
 */


int generic_permission(struct inode *inode, int mask)
{
	int ret;

	/*
         * Do the basic permission checks.
         */
	ret = acl_permission_check(inode, mask);
	if (ret != -EACCES)
		return ret;

	if (S_ISDIR(inode->i_mode)) {
		/* DACs are overridable for directories */
		if (!(mask & MAY_WRITE))
			if (capable_wrt_inode_uidgid(inode,
						     CAP_DAC_READ_SEARCH))
				return 0;
		if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE))
			return 0;
		return -EACCES;
	}

	/*
         * Searching includes executable on directories, else just read.
         */
	mask &= MAY_READ | MAY_WRITE | MAY_EXEC;
	if (mask == MAY_READ)
		if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH))
			return 0;
	/*
         * Read/write DACs are always overridable.
         * Executable DACs are overridable when there is
         * at least one exec bit set.
         */
	if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO))
		if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE))
			return 0;

	return -EACCES;
}
Contributors
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CommitProp
Linus Torvalds
42
28.77%
2
15.38%
Stephen D. Smalley
35
23.97%
1
7.69%
Linus Torvalds (pre-git)
25
17.12%
4
30.77%
Al Viro
24
16.44%
1
7.69%
Serge E. Hallyn
13
8.90%
2
15.38%
Andrew Lutomirski
3
2.05%
1
7.69%
Andrew Morton
3
2.05%
1
7.69%
Andreas Gruenbacher
1
0.68%
1
7.69%
Total
146
100.00%
13
100.00%


EXPORT_SYMBOL(generic_permission);

/*
 * We _really_ want to just do "generic_permission()" without
 * even looking at the inode->i_op values. So we keep a cache
 * flag in inode->i_opflags, that says "this has not special
 * permission function, use the fast case".
 */


static inline int do_inode_permission(struct inode *inode, int mask)
{
	if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) {
		if (likely(inode->i_op->permission))
			return inode->i_op->permission(inode, mask);

		/* This gets set once for the inode lifetime */
		spin_lock(&inode->i_lock);
		inode->i_opflags |= IOP_FASTPERM;
		spin_unlock(&inode->i_lock);
	}
	return generic_permission(inode, mask);
}

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Linus Torvalds
85
100.00%
1
100.00%
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85
100.00%
1
100.00%

/**
 * __inode_permission - Check for access rights to a given inode
 * @inode: Inode to check permission on
 * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
 *
 * Check for read/write/execute permissions on an inode.
 *
 * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask.
 *
 * This does not check for a read-only file system.  You probably want
 * inode_permission().
 */


int __inode_permission(struct inode *inode, int mask)
{
	int retval;

	if (unlikely(mask & MAY_WRITE)) {
		/*
                 * Nobody gets write access to an immutable file.
                 */
		if (IS_IMMUTABLE(inode))
			return -EPERM;

		/*
                 * Updating mtime will likely cause i_uid and i_gid to be
                 * written back improperly if their true value is unknown
                 * to the vfs.
                 */
		if (HAS_UNMAPPED_ID(inode))
			return -EACCES;
	}

	retval = do_inode_permission(inode, mask);
	if (retval)
		return retval;

	retval = devcgroup_inode_permission(inode, mask);
	if (retval)
		return retval;

	return security_inode_permission(inode, mask);
}
Contributors
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David Howells
54
59.34%
1
14.29%
Eric W. Biedermann
12
13.19%
1
14.29%
Linus Torvalds (pre-git)
11
12.09%
1
14.29%
Christoph Hellwig
7
7.69%
1
14.29%
Linus Torvalds
3
3.30%
1
14.29%
Stephen D. Smalley
3
3.30%
1
14.29%
Eryu Guan
1
1.10%
1
14.29%
Total
91
100.00%
7
100.00%


EXPORT_SYMBOL(__inode_permission);

/**
 * sb_permission - Check superblock-level permissions
 * @sb: Superblock of inode to check permission on
 * @inode: Inode to check permission on
 * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
 *
 * Separate out file-system wide checks from inode-specific permission checks.
 */


static int sb_permission(struct super_block *sb, struct inode *inode, int mask)
{
	if (unlikely(mask & MAY_WRITE)) {
		umode_t mode = inode->i_mode;

		/* Nobody gets write access to a read-only fs. */
		if ((sb->s_flags & MS_RDONLY) &&
		    (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
			return -EROFS;
	}
	return 0;
}

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David Howells
38
52.78%
1
25.00%
Christoph Hellwig
25
34.72%
1
25.00%
Miklos Szeredi
8
11.11%
1
25.00%
Trond Myklebust
1
1.39%
1
25.00%
Total
72
100.00%
4
100.00%

/**
 * inode_permission - Check for access rights to a given inode
 * @inode: Inode to check permission on
 * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
 *
 * Check for read/write/execute permissions on an inode.  We use fs[ug]id for
 * this, letting us set arbitrary permissions for filesystem access without
 * changing the "normal" UIDs which are used for other things.
 *
 * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask.
 */


int inode_permission(struct inode *inode, int mask)
{
	int retval;

	retval = sb_permission(inode->i_sb, inode, mask);
	if (retval)
		return retval;
	return __inode_permission(inode, mask);
}
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David Howells
18
40.91%
1
20.00%
Serge E. Hallyn
15
34.09%
1
20.00%
Linus Torvalds (pre-git)
8
18.18%
1
20.00%
Stephen D. Smalley
2
4.55%
1
20.00%
Al Viro
1
2.27%
1
20.00%
Total
44
100.00%
5
100.00%


EXPORT_SYMBOL(inode_permission);

/**
 * path_get - get a reference to a path
 * @path: path to get the reference to
 *
 * Given a path increment the reference count to the dentry and the vfsmount.
 */


void path_get(const struct path *path)
{
	mntget(path->mnt);
	dget(path->dentry);
}
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Jan Blunck
24
96.00%
1
50.00%
Al Viro
1
4.00%
1
50.00%
Total
25
100.00%
2
100.00%


EXPORT_SYMBOL(path_get);

/**
 * path_put - put a reference to a path
 * @path: path to put the reference to
 *
 * Given a path decrement the reference count to the dentry and the vfsmount.
 */


void path_put(const struct path *path)
{
	dput(path->dentry);
	mntput(path->mnt);
}
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Linus Torvalds (pre-git)
17
68.00%
1
25.00%
Jan Blunck
7
28.00%
2
50.00%
Al Viro
1
4.00%
1
25.00%
Total
25
100.00%
4
100.00%


EXPORT_SYMBOL(path_put);


#define EMBEDDED_LEVELS 2

struct nameidata {
	
struct path	path;
	
struct qstr	last;
	
struct path	root;
	
struct inode	*inode; /* path.dentry.d_inode */
	
unsigned int	flags;
	

unsigned	seq, m_seq;
	
int		last_type;
	
unsigned	depth;
	
int		total_link_count;
	
struct saved {
		
struct path link;
		
struct delayed_call done;
		
const char *name;
		
unsigned seq;
	

} *stack, internal[EMBEDDED_LEVELS];
	
struct filename	*name;
	
struct nameidata *saved;
	
struct inode	*link_inode;
	
unsigned	root_seq;
	
int		dfd;

} __randomize_layout;



static void set_nameidata(struct nameidata *p, int dfd, struct filename *name)
{
	struct nameidata *old = current->nameidata;
	p->stack = p->internal;
	p->dfd = dfd;
	p->name = name;
	p->total_link_count = old ? old->total_link_count : 0;
	p->saved = old;
	current->nameidata = p;
}

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Al Viro
42
58.33%
3
75.00%
Neil Brown
30
41.67%
1
25.00%
Total
72
100.00%
4
100.00%



static void restore_nameidata(void)
{
	struct nameidata *now = current->nameidata, *old = now->saved;

	current->nameidata = old;
	if (old)
		old->total_link_count = now->total_link_count;
	if (now->stack != now->internal)
		kfree(now->stack);
}

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Neil Brown
30
50.85%
1
33.33%
Al Viro
29
49.15%
2
66.67%
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59
100.00%
3
100.00%



static int __nd_alloc_stack(struct nameidata *nd)
{
	struct saved *p;

	if (nd->flags & LOOKUP_RCU) {
		p= kmalloc(MAXSYMLINKS * sizeof(struct saved),
				  GFP_ATOMIC);
		if (unlikely(!p))
			return -ECHILD;
	} else {
		p= kmalloc(MAXSYMLINKS * sizeof(struct saved),
				  GFP_KERNEL);
		if (unlikely(!p))
			return -ENOMEM;
	}
	memcpy(p, nd->internal, sizeof(nd->internal));
	nd->stack = p;
	return 0;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Al Viro
108
100.00%
2
100.00%
Total
108
100.00%
2
100.00%

/**
 * path_connected - Verify that a path->dentry is below path->mnt.mnt_root
 * @path: nameidate to verify
 *
 * Rename can sometimes move a file or directory outside of a bind
 * mount, path_connected allows those cases to be detected.
 */


static bool path_connected(const struct path *path)
{
	struct vfsmount *mnt = path->mnt;

	/* Only bind mounts can have disconnected paths */
	if (mnt->mnt_root == mnt->mnt_sb->s_root)
		return true;

	return is_subdir(path->dentry, mnt->mnt_root);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Eric W. Biedermann
49
100.00%
1
100.00%
Total
49
100.00%
1
100.00%



static inline int nd_alloc_stack(struct nameidata *nd)
{
	if (likely(nd->depth != EMBEDDED_LEVELS))
		return 0;
	if (likely(nd->stack != nd->internal))
		return 0;
	return __nd_alloc_stack(nd);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Al Viro
48
100.00%
1
100.00%
Total
48
100.00%
1
100.00%



static void drop_links(struct nameidata *nd)
{
	int i = nd->depth;
	while (i--) {
		struct saved *last = nd->stack + i;
		do_delayed_call(&last->done);
		clear_delayed_call(&last->done);
	}
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Al Viro
52
100.00%
2
100.00%
Total
52
100.00%
2
100.00%



static void terminate_walk(struct nameidata *nd)
{
	drop_links(nd);
	if (!(nd->flags & LOOKUP_RCU)) {
		int i;
		path_put(&nd->path);
		for (i = 0; i < nd->depth; i++)
			path_put(&nd->stack[i].link);
		if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) {
			path_put(&nd->root);
			nd->root.mnt = NULL;
		}
	} else {
		nd->flags &= ~LOOKUP_RCU;
		if (!(nd->flags & LOOKUP_ROOT))
			nd->root.mnt = NULL;
		rcu_read_unlock();
	}
	nd->depth = 0;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Al Viro
141
100.00%
2
100.00%
Total
141
100.00%
2
100.00%

/* path_put is needed afterwards regardless of success or failure */


static bool legitimize_path(struct nameidata *nd,
			    struct path *path, unsigned seq)
{
	int res = __legitimize_mnt(path->mnt, nd->m_seq);
	if (unlikely(res)) {
		if (res > 0)
			path->mnt = NULL;
		path->dentry = NULL;
		return false;
	}
	if (unlikely(!lockref_get_not_dead(&path->dentry->d_lockref))) {
		path->dentry = NULL;
		return false;
	}
	return !read_seqcount_retry(&path->dentry->d_seq, seq);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Al Viro
104
100.00%
1
100.00%
Total
104
100.00%
1
100.00%



static bool legitimize_links(struct nameidata *nd)
{
	int i;
	for (i = 0; i < nd->depth; i++) {
		struct saved *last = nd->stack + i;
		if (unlikely(!legitimize_path(nd, &last->link, last->seq))) {
			drop_links(nd);
			nd->depth = i + 1;
			return false;
		}
	}
	return true;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Al Viro
83
100.00%
1
100.00%
Total
83
100.00%
1
100.00%

/*
 * Path walking has 2 modes, rcu-walk and ref-walk (see
 * Documentation/filesystems/path-lookup.txt).  In situations when we can't
 * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab
 * normal reference counts on dentries and vfsmounts to transition to ref-walk
 * mode.  Refcounts are grabbed at the last known good point before rcu-walk
 * got stuck, so ref-walk may continue from there. If this is not successful
 * (eg. a seqcount has changed), then failure is returned and it's up to caller
 * to restart the path walk from the beginning in ref-walk mode.
 */

/**
 * unlazy_walk - try to switch to ref-walk mode.
 * @nd: nameidata pathwalk data
 * Returns: 0 on success, -ECHILD on failure
 *
 * unlazy_walk attempts to legitimize the current nd->path and nd->root
 * for ref-walk mode.
 * Must be called from rcu-walk context.
 * Nothing should touch nameidata between unlazy_walk() failure and
 * terminate_walk().
 */


static int unlazy_walk(struct nameidata *nd)
{
	struct dentry *parent = nd->path.dentry;

	BUG_ON(!(nd->flags & LOOKUP_RCU));

	nd->flags &= ~LOOKUP_RCU;
	if (unlikely(!legitimize_links(nd)))
		goto out2;
	if (unlikely(!legitimize_path(nd, &nd->path, nd->seq)))
		goto out1;
	if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) {
		if (unlikely(!legitimize_path(nd, &nd->root, nd->root_seq)))
			goto out;
	}
	rcu_read_unlock();
	BUG_ON(nd->inode != parent->d_inode);
	return 0;

out2:
	nd->path.mnt = NULL;
	nd->path.dentry = NULL;
out1:
	if (!(nd->flags & LOOKUP_ROOT))
		nd->root.mnt = NULL;
out:
	rcu_read_unlock();
	return -ECHILD;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Al Viro
145
78.38%
6
54.55%
Nicholas Piggin
20
10.81%
1
9.09%
Trond Myklebust
14
7.57%
1
9.09%
Ian Kent
3
1.62%
1
9.09%
Josef 'Jeff' Sipek
2
1.08%
1
9.09%
Linus Torvalds
1
0.54%
1
9.09%
Total
185
100.00%
11
100.00%

/**
 * unlazy_child - try to switch to ref-walk mode.
 * @nd: nameidata pathwalk data
 * @dentry: child of nd->path.dentry
 * @seq: seq number to check dentry against
 * Returns: 0 on success, -ECHILD on failure
 *
 * unlazy_child attempts to legitimize the current nd->path, nd->root and dentry
 * for ref-walk mode.  @dentry must be a path found by a do_lookup call on
 * @nd.  Must be called from rcu-walk context.
 * Nothing should touch nameidata between unlazy_child() failure and
 * terminate_walk().
 */


static int unlazy_child(struct nameidata *nd, struct dentry *dentry, unsigned seq)
{
	BUG_ON(!(nd->flags & LOOKUP_RCU));

	nd->flags &= ~LOOKUP_RCU;
	if (unlikely(!legitimize_links(nd)))
		goto out2;
	if (unlikely(!legitimize_mnt(nd->path.mnt, nd->m_seq)))
		goto out2;
	if (unlikely(!lockref_get_not_dead(&nd->path.dentry->d_lockref)))
		goto out1;

	/*
         * We need to move both the parent and the dentry from the RCU domain
         * to be properly refcounted. And the sequence number in the dentry
         * validates *both* dentry counters, since we checked the sequence
         * number of the parent after we got the child sequence number. So we
         * know the parent must still be valid if the child sequence number is
         */
	if (unlikely(!lockref_get_not_dead(&dentry->d_lockref)))
		goto out;
	if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) {
		rcu_read_unlock();
		dput(dentry);
		goto drop_root_mnt;
	}
	/*
         * Sequence counts matched. Now make sure that the root is
         * still valid and get it if required.
         */
	if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) {
		if (unlikely(!legitimize_path(nd, &nd->root, nd->root_seq))) {
			rcu_read_unlock();
			dput(dentry);
			return -ECHILD;
		}
	}

	rcu_read_unlock();
	return 0;

out2:
	nd->path.mnt = NULL;
out1:
	nd->path.dentry = NULL;
out:
	rcu_read_unlock();
drop_root_mnt:
	if (!(nd->flags & LOOKUP_ROOT))
		nd->root.mnt = NULL;
	return -ECHILD;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Al Viro
154
61.35%
7
43.75%
Linus Torvalds
67
26.69%
4
25.00%
Nicholas Piggin
19
7.57%
1
6.25%
Ian Kent
7
2.79%
1
6.25%
Stephen D. Smalley
2
0.80%
1
6.25%
Hanna V. Linder
1
0.40%
1
6.25%
Christoph Hellwig
1
0.40%
1
6.25%
Total
251
100.00%
16
100.00%



static inline int d_revalidate(struct dentry *dentry, unsigned int flags)
{
	if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE))
		return dentry->d_op->d_revalidate(dentry, flags);
	else
		return 1;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Nicholas Piggin
23
53.49%
1
20.00%
Al Viro
20
46.51%
4
80.00%
Total
43
100.00%
5
100.00%

/**
 * complete_walk - successful completion of path walk
 * @nd:  pointer nameidata
 *
 * If we had been in RCU mode, drop out of it and legitimize nd->path.
 * Revalidate the final result, unless we'd already done that during
 * the path walk or the filesystem doesn't ask for it.  Return 0 on
 * success, -error on failure.  In case of failure caller does not
 * need to drop nd->path.
 */


static int complete_walk(struct nameidata *nd)
{
	struct dentry *dentry = nd->path.dentry;
	int status;

	if (nd->flags & LOOKUP_RCU) {
		if (!(nd->flags & LOOKUP_ROOT))
			nd->root.mnt = NULL;
		if (unlikely(unlazy_walk(nd)))
			return -ECHILD;
	}

	if (likely(!(nd->flags & LOOKUP_JUMPED)))
		return 0;

	if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE)))
		return 0;

	status = dentry->d_op->d_weak_revalidate(dentry, nd->flags);
	if (status > 0)
		return 0;

	if (!status)
		status = -ESTALE;

	return status;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Al Viro
68
48.92%
6
54.55%
Nicholas Piggin
57
41.01%
2
18.18%
Linus Torvalds (pre-git)
8
5.76%
1
9.09%
Jeff Layton
5
3.60%
1
9.09%
Linus Torvalds
1
0.72%
1
9.09%
Total
139
100.00%
11
100.00%



static void set_root(struct nameidata *nd)
{
	struct fs_struct *fs = current->fs;

	if (nd->flags & LOOKUP_RCU) {
		unsigned seq;

		do {
			seq = read_seqcount_begin(&fs->seq);
			nd->root = fs->root;
			nd->root_seq = __read_seqcount_begin(&nd->root.dentry->d_seq);
		} while (read_seqcount_retry(&fs->seq, seq));
	} else {
		get_fs_root(fs, &nd->root);
	}
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Nicholas Piggin
45
46.88%
2
25.00%
Al Viro
30
31.25%
3
37.50%
Tim Chen
13
13.54%
1
12.50%
Linus Torvalds (pre-git)
5
5.21%
1
12.50%
Andrew Morton
3
3.12%
1
12.50%
Total
96
100.00%
8
100.00%



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

Contributors
Person
Tokens
Prop
Commits
CommitProp
Nicholas Piggin
27
64.29%
1
14.29%
Linus Torvalds (pre-git)
6
14.29%
1
14.29%
Al Viro
4
9.52%
3
42.86%
Andrew Morton
3
7.14%
1
14.29%
Jan Blunck
2
4.76%
1
14.29%
Total
42
100.00%
7
100.00%



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

Contributors
Person
Tokens
Prop
Commits
CommitProp
Nicholas Piggin
81
100.00%
3
100.00%
Total
81
100.00%
3
100.00%



static int nd_jump_root(struct nameidata *nd)
{
	if (nd->flags & LOOKUP_RCU) {
		struct dentry *d;
		nd->path = nd->root;
		d = nd->path.dentry;
		nd->inode = d->d_inode;
		nd->seq = nd->root_seq;
		if (unlikely(read_seqcount_retry(&d->d_seq, nd->seq)))
			return -ECHILD;
	} else {
		path_put(&nd->path);
		nd->path = nd->root;
		path_get(&nd->path);
		nd->inode = nd->path.dentry->d_inode;
	}
	nd->flags |= LOOKUP_JUMPED;
	return 0;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Al Viro
127
100.00%
1
100.00%
Total
127
100.00%
1
100.00%

/*
 * Helper to directly jump to a known parsed path from ->get_link,
 * caller must have taken a reference to path beforehand.
 */


void nd_jump_link(struct path *path)
{
	struct nameidata *nd = current->nameidata;
	path_put(&nd->path);

	nd->path = *path;
	nd->inode = nd->path.dentry->d_inode;
	nd->flags |= LOOKUP_JUMPED;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Christoph Hellwig
43
82.69%
1
50.00%
Al Viro
9
17.31%
1
50.00%
Total
52
100.00%
2
100.00%



static inline void put_link(struct nameidata *nd)
{
	struct saved *last = nd->stack + --nd->depth;
	do_delayed_call(&last->done);
	if (!(nd->flags & LOOKUP_RCU))
		path_put(&last->link);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Al Viro
53
100.00%
5
100.00%
Total
53
100.00%
5
100.00%


int sysctl_protected_symlinks __read_mostly = 0;

int sysctl_protected_hardlinks __read_mostly = 0;

/**
 * may_follow_link - Check symlink following for unsafe situations
 * @nd: nameidata pathwalk data
 *
 * In the case of the sysctl_protected_symlinks sysctl being enabled,
 * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is
 * in a sticky world-writable directory. This is to protect privileged
 * processes from failing races against path names that may change out
 * from under them by way of other users creating malicious symlinks.
 * It will permit symlinks to be followed only when outside a sticky
 * world-writable directory, or when the uid of the symlink and follower
 * match, or when the directory owner matches the symlink's owner.
 *
 * Returns 0 if following the symlink is allowed, -ve on error.
 */


static inline int may_follow_link(struct nameidata *nd)
{
	const struct inode *inode;
	const struct inode *parent;
	kuid_t puid;

	if (!sysctl_protected_symlinks)
		return 0;

	/* Allowed if owner and follower match. */
	inode = nd->link_inode;
	if (uid_eq(current_cred()->fsuid, inode->i_uid))
		return 0;

	/* Allowed if parent directory not sticky and world-writable. */
	parent = nd->inode;
	if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH))
		return 0;

	/* Allowed if parent directory and link owner match. */
	puid = parent->i_uid;
	if (uid_valid(puid) && uid_eq(puid, inode->i_uid))
		return 0;

	if (nd->flags & LOOKUP_RCU)
		return -ECHILD;

	audit_log_link_denied("follow_link", &nd->stack[0].link);
	return -EACCES;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Kees Cook
93
63.70%
1
11.11%
Al Viro
23
15.75%
5
55.56%
Seth Forshee
15
10.27%
1
11.11%
Eric W. Biedermann
8
5.48%
1
11.11%
Sasha Levin
7
4.79%
1
11.11%
Total
146
100.00%
9
100.00%

/**
 * safe_hardlink_source - Check for safe hardlink conditions
 * @inode: the source inode to hardlink from
 *
 * Return false if at least one of the following conditions:
 *    - inode is not a regular file
 *    - inode is setuid
 *    - inode is setgid and group-exec
 *    - access failure for read and write
 *
 * Otherwise returns true.
 */


static bool safe_hardlink_source(struct inode *inode)
{
	umode_t mode = inode->i_mode;

	/* Special files should not get pinned to the filesystem. */
	if (!S_ISREG(mode))
		return false;

	/* Setuid files should not get pinned to the filesystem. */
	if (mode & S_ISUID)
		return false;

	/* Executable setgid files should not get pinned to the filesystem. */
	if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP))
		return false;

	/* Hardlinking to unreadable or unwritable sources is dangerous. */
	if (inode_permission(inode, MAY_READ | MAY_WRITE))
		return false;

	return true;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Kees Cook
80
100.00%
1
100.00%
Total
80
100.00%
1
100.00%

/**
 * may_linkat - Check permissions for creating a hardlink
 * @link: the source to hardlink from
 *
 * Block hardlink when all of:
 *  - sysctl_protected_hardlinks enabled
 *  - fsuid does not match inode
 *  - hardlink source is unsafe (see safe_hardlink_source() above)
 *  - not CAP_FOWNER in a namespace with the inode owner uid mapped
 *
 * Returns 0 if successful, -ve on error.
 */


static int may_linkat(struct path *link)
{
	struct inode *inode;

	if (!sysctl_protected_hardlinks)
		return 0;

	inode = link->dentry->d_inode;

	/* Source inode owner (or CAP_FOWNER) can hardlink all they like,
         * otherwise, it must be a safe source.
         */
	if (safe_hardlink_source(inode) || inode_owner_or_capable(inode))
		return 0;

	audit_log_link_denied("linkat", link);
	return -EPERM;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Kees Cook
57
96.61%
3
75.00%
Eric W. Biedermann
2
3.39%
1
25.00%
Total
59
100.00%
4
100.00%


static __always_inline

const char *get_link(struct nameidata *nd)
{
	struct saved *last = nd->stack + nd->depth - 1;
	struct dentry *dentry = last->link.dentry;
	struct inode *inode = nd->link_inode;
	int error;
	const char *res;

	if (!(nd->flags & LOOKUP_RCU)) {
		touch_atime(&last->link);
		cond_resched();
	} else if (atime_needs_update_rcu(&last->link, inode)) {
		if (unlikely(unlazy_walk(nd)))
			return ERR_PTR(-ECHILD);
		touch_atime(&last->link);
	}

	error = security_inode_follow_link(dentry, inode,
					   nd->flags & LOOKUP_RCU);
	if (unlikely(error))
		return ERR_PTR(error);

	nd->last_type = LAST_BIND;
	res = inode->i_link;
	if (!res) {
		const char * (*get)(struct dentry *, struct inode *,
				struct delayed_call *);
		get = inode->i_op->get_link;
		if (nd->flags & LOOKUP_RCU) {
			res = get(NULL, inode, &last->done);
			if (res == ERR_PTR(-ECHILD)) {
				if (unlikely(unlazy_walk(nd)))
					return ERR_PTR(-ECHILD);
				res = get(dentry, inode, &last->done);
			}
		} else {
			res = get(dentry, inode, &last->done);
		}
		if (IS_ERR_OR_NULL(res))
			return res;
	}
	if (*res == '/') {
		if (!nd->root.mnt)
			set_root(nd);
		if (unlikely(nd_jump_root(nd)))
			return ERR_PTR(-ECHILD);
		while (unlikely(*++res == '/'))
			;
	}
	if (!*res)
		res = NULL;
	return res;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Al Viro
294
82.58%
20
76.92%
Neil Brown
40
11.24%
2
7.69%
Nicholas Piggin
18
5.06%
2
7.69%
Linus Torvalds (pre-git)
3
0.84%
1
3.85%
Miklos Szeredi
1
0.28%
1
3.85%
Total
356
100.00%
26
100.00%

/*
 * follow_up - Find the mountpoint of path's vfsmount
 *
 * Given a path, find the mountpoint of its source file system.
 * Replace @path with the path of the mountpoint in the parent mount.
 * Up is towards /.
 *
 * Return 1 if we went up a level and 0 if we were already at the
 * root.
 */


int follow_up(struct path *path)
{
	struct mount *mnt = real_mount(path->mnt);
	struct mount *parent;
	struct dentry *mountpoint;

	read_seqlock_excl(&mount_lock);
	parent = mnt->mnt_parent;
	if (parent == mnt) {
		read_sequnlock_excl(&mount_lock);
		return 0;
	}
	mntget(&parent->mnt);
	mountpoint = dget(mnt->mnt_mountpoint);
	read_sequnlock_excl(&mount_lock);
	dput(path->dentry);
	path->dentry = mountpoint;
	mntput(path->mnt);
	path->mnt = &parent->mnt;
	return 1;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
Nicholas Piggin
88
75.86%
1
25.00%
Al Viro
25
21.55%
2
50.00%
Andi Kleen
3
2.59%
1
25.00%
Total
116
100.00%
4
100.00%


EXPORT_SYMBOL(follow_up);

/*
 * Perform an automount
 * - return -EISDIR to tell follow_managed() to stop and return the path we
 *   were called with.
 */


static int follow_automount(struct path *path, struct nameidata *nd,
			    bool *need_mntput)
{
	struct vfsmount *mnt;
	int err;

	if (!path->dentry->d_op || !path->dentry->d_op->d_automount)
		return -EREMOTE;

	/* We don't want to mount if someone's just doing a stat -
         * unless they're stat'ing a directory and appended a '/' to
         * the name.
         *
         * We do, however, want to mount if someone wants to open or
         * create a file of any type under the mountpoint, wants to
         * traverse through the mountpoint or wants to open the
         * mounted directory.  Also, autofs may mark negative dentries
         * as being automount points.  These will need the attentions
         * of the daemon to instantiate them before they can be used.
         */
	if (!(nd->flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY |
			   LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) &&
	    path->dentry->d_inode)
		return -EISDIR;

	if (path->dentry->d_sb->s_user_ns != &init_user_ns)
		return -EACCES;

	nd->total_link_count++;
	if (nd->total_link_count >= 40)
		return -ELOOP;

	mnt = path->dentry->d_op->d_automount(path);
	if (IS_ERR(mnt)) {
		/*
                 * The filesystem is allowed to return -EISDIR here to indicate
                 * it doesn't want to automount.  For instance, autofs would do
                 * this so that its userspace daemon can mount on this dentry.
                 *
                 * However, we can only permit this if it's a terminal point in
                 * the path being looked up; if it wasn't then the remainder of
                 * the path is inaccessible and we should say so.
                 */
		if (PTR_ERR(mnt) == -EISDIR && (nd->flags & LOOKUP_PARENT))
			return -EREMOTE;
		return PTR_ERR(mnt);
	}

	if (!mnt) /* mount collision */
		return 0;

	if (!*need_mntput) {
		/* lock_mount() may release path->mnt on error */
		mntget(path->mnt);
		*need_mntput = true;
	}
	err = finish_automount(mnt, path);

	switch (err) {
	case -EBUSY:
		/* Someone else made a mount here whilst we were busy */
		return 0;
	case 0:
		path_put(path);
		path->mnt = mnt;
		path->dentry = dget(mnt->mnt_root);
		return 0;
	default:
		return err;
	}

}

Contributors
Person
Tokens
Prop
Commits
CommitProp
David Howells
155
61.51%
3
27.27%
Nicholas Piggin
37
14.68%
1
9.09%
Al Viro
30
11.90%
3
27.27%
Eric W. Biedermann
17
6.75%
1
9.09%
Neil Brown
10
3.97%
1
9.09%
Linus Torvalds
2
0.79%
1
9.09%
Miklos Szeredi
1
0.40%
1
9.09%
Total
252
100.00%
11
100.00%

/*
 * Handle a dentry that is managed in some way.
 * - Flagged for transit management (autofs)
 * - Flagged as mountpoint
 * - Flagged as automount point
 *
 * This may only be called in refwalk mode.
 *
 * Serialization is taken care of in namespace.c
 */


static int follow_managed(struct path *path, struct nameidata *nd)
{
	struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */
	unsigned managed;
	bool need_mntput = false;
	int ret = 0;

	/* Given that we're not holding a lock here, we retain the value in a
         * local variable for each dentry as we look at it so that we don't see
         * the components of that value change under us */
	while (managed = ACCESS_ONCE(path->dentry->d_flags),
	       managed &= DCACHE_MANAGED_DENTRY,
	       unlikely(managed != 0)) {
		/* Allow the filesystem to manage the transit without i_mutex
                 * being held. */
		if (managed & DCACHE_MANAGE_TRANSIT) {
			BUG_ON(!path->dentry->d_op);
			BUG_ON(!path->dentry->d_op->d_manage);
			ret = path->dentry->d_op->d_manage(path, false);
			if (ret < 0)
				break;
		}

		/* Transit to a mounted filesystem. */
		if (managed & DCACHE_MOUNTED) {
			struct vfsmount *mounted = lookup_mnt(path);
			if (mounted) {
				dput(path->dentry);
				if (need_mntput)
					mntput(path->mnt);
				path->mnt = mounted;
				path->dentry = dget(mounted->mnt_root);
				need_mntput = true;
				continue;
			}

			/* Something is mounted on this dentry in another
                         * namespace and/or whatever was mounted there in this
                         * namespace got unmounted before lookup_mnt() could
                         * get it */
		}

		/* Handle an automount point */
		if (managed & DCACHE_NEED_AUTOMOUNT) {
			ret = follow_automount(path, nd, &need_mntput);
			if (ret < 0)
				break;
			continue;
		}

		/* We didn't change the current path point */
		break;
	}

	if (need_mntput && path->mnt == mnt)
		mntput(path->mnt);
	if (ret == -EISDIR || !ret)
		ret = 1;
	if (need_mntput)
		nd->flags |= LOOKUP_JUMPED;
	if (unlikely(ret < 0))
		path_put_conditional(path, nd);
	return ret;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
David Howells
124
44.93%
2
22.22%
Al Viro
74
26.81%
5
55.56%
Nicholas Piggin
73
26.45%
1
11.11%
Neil Brown
5
1.81%
1
11.11%
Total
276
100.00%
9
100.00%



int follow_down_one(struct path *path)
{
	struct vfsmount *mounted;

	mounted = lookup_mnt(path);
	if (mounted) {
		dput(path->dentry);
		mntput(path->mnt);
		path->mnt = mounted;
		path->dentry = dget(mounted->mnt_root);
		return 1;
	}
	return 0;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
Nicholas Piggin
52
80.00%
1
33.33%
David Howells
13
20.00%
2
66.67%
Total
65
100.00%
3
100.00%


EXPORT_SYMBOL(follow_down_one);



static inline int managed_dentry_rcu(const struct path *path)
{
	return (path->dentry->d_flags & DCACHE_MANAGE_TRANSIT) ?
		path->dentry->d_op->d_manage(path, true) : 0;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Ian Kent
34
87.18%
2
66.67%
Neil Brown
5
12.82%
1
33.33%
Total
39
100.00%
3
100.00%

/*
 * Try to skip to top of mountpoint pile in rcuwalk mode.  Fail if
 * we meet a managed dentry that would need blocking.
 */


static bool __follow_mount_rcu(struct nameidata *nd, struct path *path,
			       struct inode **inode, unsigned *seqp)
{
	for (;;) {
		struct mount *mounted;
		/*
                 * Don't forget we might have a non-mountpoint managed dentry
                 * that wants to block transit.
                 */
		switch (managed_dentry_rcu(path)) {
		case -ECHILD:
		default:
			return false;
		case -EISDIR:
			return true;
		case 0:
			break;
		}

		if (!d_mountpoint(path->dentry))
			return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT);

		mounted = __lookup_mnt(path->mnt, path->dentry);
		if (!mounted)
			break;
		path->mnt = &mounted->mnt;
		path->dentry = mounted->mnt.mnt_root;
		nd->flags |= LOOKUP_JUMPED;
		*seqp = read_seqcount_begin(&path->dentry->d_seq);
		/*
                 * Update the inode too. We don't need to re-check the
                 * dentry sequence number here after this d_inode read,
                 * because a mount-point is always pinned.
                 */
		*inode = path->dentry->d_inode;
	}
	return !read_seqretry(&mount_lock, nd->m_seq) &&
		!(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
David Howells
50
27.93%
3
21.43%
Neil Brown
41
22.91%
1
7.14%
Nicholas Piggin
31
17.32%
1
7.14%
Al Viro
30
16.76%
7
50.00%
Ian Kent
17
9.50%
1
7.14%
Linus Torvalds
10
5.59%
1
7.14%
Total
179
100.00%
14
100.00%



static int follow_dotdot_rcu(struct nameidata *nd)
{
	struct inode *inode = nd->inode;

	while (1) {
		if (path_equal(&nd->path, &nd->root))
			break;
		if (nd->path.dentry != nd->path.mnt->mnt_root) {
			struct dentry *old = nd->path.dentry;
			struct dentry *parent = old->d_parent;
			unsigned seq;

			inode = parent->d_inode;
			seq = read_seqcount_begin(&parent->d_seq);
			if (unlikely(read_seqcount_retry(&old->d_seq, nd->seq)))
				return -ECHILD;
			nd->path.dentry = parent;
			nd->seq = seq;
			if (unlikely(!path_connected(&nd->path)))
				return -ENOENT;
			break;
		} else {
			struct mount *mnt = real_mount(nd->path.mnt);
			struct mount *mparent = mnt->mnt_parent;
			struct dentry *mountpoint = mnt->mnt_mountpoint;
			struct inode *inode2 = mountpoint->d_inode;
			unsigned seq = read_seqcount_begin(&mountpoint->d_seq);
			if (unlikely(read_seqretry(&mount_lock, nd->m_seq)))
				return -ECHILD;
			if (&mparent->mnt == nd->path.mnt)
				break;
			/* we know that mountpoint was pinned */
			nd->path.dentry = mountpoint;
			nd->path.mnt = &mparent->mnt;
			inode = inode2;
			nd->seq = seq;
		}
	}
	while (unlikely(d_mountpoint(nd->path.dentry))) {
		struct mount *mounted;
		mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry);
		if (unlikely(read_seqretry(&mount_lock, nd->m_seq)))
			return -ECHILD;
		if (!mounted)
			break;
		nd->path.mnt = &mounted->mnt;
		nd->path.dentry = mounted->mnt.mnt_root;
		inode = nd->path.dentry->d_inode;
		nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
	}
	nd->inode = inode;
	return 0;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Al Viro
239
60.97%
3
60.00%
Nicholas Piggin
135
34.44%
1
20.00%
Eric W. Biedermann
18
4.59%
1
20.00%
Total
392
100.00%
5
100.00%

/*
 * Follow down to the covering mount currently visible to userspace.  At each
 * point, the filesystem owning that dentry may be queried as to whether the
 * caller is permitted to proceed or not.
 */


int follow_down(struct path *path)
{
	unsigned managed;
	int ret;

	while (managed = ACCESS_ONCE(path->dentry->d_flags),
	       unlikely(managed & DCACHE_MANAGED_DENTRY)) {
		/* Allow the filesystem to manage the transit without i_mutex
                 * being held.
                 *
                 * We indicate to the filesystem if someone is trying to mount
                 * something here.  This gives autofs the chance to deny anyone
                 * other than its daemon the right to mount on its
                 * superstructure.
                 *
                 * The filesystem may sleep at this point.
                 */
		if (managed & DCACHE_MANAGE_TRANSIT) {
			BUG_ON(!path->dentry->d_op);
			BUG_ON(!path->dentry->d_op->d_manage);
			ret = path->dentry->d_op->d_manage(path, false);
			if (ret < 0)
				return ret == -EISDIR ? 0 : ret;
		}

		/* Transit to a mounted filesystem. */
		if (managed & DCACHE_MOUNTED) {
			struct vfsmount *mounted = lookup_mnt(path);
			if (!mounted)
				break;
			dput(path->dentry);
			mntput(path->mnt);
			path->mnt = mounted;
			path->dentry = dget(mounted->mnt_root);
			continue;
		}

		/* Don't handle automount points here */
		break;
	}
	return 0;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
David Howells
161
99.38%
1
50.00%
Al Viro
1
0.62%
1
50.00%
Total
162
100.00%
2
100.00%


EXPORT_SYMBOL(follow_down);

/*
 * Skip to top of mountpoint pile in refwalk mode for follow_dotdot()
 */


static void follow_mount(struct path *path)
{
	while (d_mountpoint(path->dentry)) {
		struct vfsmount *mounted = lookup_mnt(path);
		if (!mounted)
			break;
		dput(path->dentry);
		mntput(path->mnt);
		path->mnt = mounted;
		path->dentry = dget(mounted->mnt_root);
	}
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
David Howells
69
100.00%
1
100.00%
Total
69
100.00%
1
100.00%



static int path_parent_directory(struct path *path)
{
	struct dentry *old = path->dentry;
	/* rare case of legitimate dget_parent()... */
	path->dentry = dget_parent(path->dentry);
	dput(old);
	if (unlikely(!path_connected(path)))
		return -ENOENT;
	return 0;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Eric W. Biedermann
55
100.00%
1
100.00%
Total
55
100.00%
1
100.00%



static int follow_dotdot(struct nameidata *nd)
{
	while(1) {
		if (nd->path.dentry == nd->root.dentry &&
		    nd->path.mnt == nd->root.mnt) {
			break;
		}
		if (nd->path.dentry != nd->path.mnt->mnt_root) {
			int ret = path_parent_directory(&nd->path);
			if (ret)
				return ret;
			break;
		}
		if (!follow_up(&nd->path))
			break;
	}
	follow_mount(&nd->path);
	nd->inode = nd->path.dentry->d_inode;
	return 0;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Nicholas Piggin
101
85.59%
1
33.33%
Eric W. Biedermann
17
14.41%
2
66.67%
Total
118
100.00%
3
100.00%

/*
 * This looks up the name in dcache and possibly revalidates the found dentry.
 * NULL is returned if the dentry does not exist in the cache.
 */


static struct dentry *lookup_dcache(const struct qstr *name,
				    struct dentry *dir,
				    unsigned int flags)
{
	struct dentry *dentry = d_lookup(dir, name);
	if (dentry) {
		int error = d_revalidate(dentry, flags);
		if (unlikely(error <= 0)) {
			if (!error)
				d_invalidate(dentry);
			dput(dentry);
			return ERR_PTR(error);
		}
	}
	return dentry;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Nicholas Piggin
38
44.19%
1
14.29%
Miklos Szeredi
32
37.21%
1
14.29%
Al Viro
16
18.60%
5
71.43%
Total
86
100.00%
7
100.00%

/*
 * Call i_op->lookup on the dentry.  The dentry must be negative and
 * unhashed.
 *
 * dir->d_inode->i_mutex must be held
 */


static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry,
				  unsigned int flags)
{
	struct dentry *old;

	/* Don't create child dentry for a dead directory. */
	if (unlikely(IS_DEADDIR(dir))) {
		dput(dentry);
		return ERR_PTR(-ENOENT);
	}

	old = dir->i_op->lookup(dir, dentry, flags);
	if (unlikely(old)) {
		dput(dentry);
		dentry = old;
	}
	return dentry;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Josef Bacik
71
80.68%
1
20.00%
Miklos Szeredi
13
14.77%
2
40.00%
Al Viro
4
4.55%
2
40.00%
Total
88
100.00%
5
100.00%



static struct dentry *__lookup_hash(const struct qstr *name,
		struct dentry *base, unsigned int flags)
{
	struct dentry *dentry = lookup_dcache(name, base, flags);

	if (dentry)
		return dentry;

	dentry = d_alloc(base, name);
	if (unlikely(!dentry))
		return ERR_PTR(-ENOMEM);

	return lookup_real(base->d_inode, dentry, flags);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Al Viro
71
88.75%
5
83.33%
Miklos Szeredi
9
11.25%
1
16.67%
Total
80
100.00%
6
100.00%



static int lookup_fast(struct nameidata *nd,
		       struct path *path, struct inode **inode,
		       unsigned *seqp)
{
	struct vfsmount *mnt = nd->path.mnt;
	struct dentry *dentry, *parent = nd->path.dentry;
	int status = 1;
	int err;

	/*
         * Rename seqlock is not required here because in the off chance
         * of a false negative due to a concurrent rename, the caller is
         * going to fall back to non-racy lookup.
         */
	if (nd->flags & LOOKUP_RCU) {
		unsigned seq;
		bool negative;
		dentry = __d_lookup_rcu(parent, &nd->last, &seq);
		if (unlikely(!dentry)) {
			if (unlazy_walk(nd))
				return -ECHILD;
			return 0;
		}

		/*
                 * This sequence count validates that the inode matches
                 * the dentry name information from lookup.
                 */
		*inode = d_backing_inode(dentry);
		negative = d_is_negative(dentry);
		if (unlikely(read_seqcount_retry(&dentry->d_seq, seq)))
			return -ECHILD;

		/*
                 * This sequence count validates that the parent had no
                 * changes while we did the lookup of the dentry above.
                 *
                 * The memory barrier in read_seqcount_begin of child is
                 *  enough, we can use __read_seqcount_retry here.
                 */
		if (unlikely(__read_seqcount_retry(&parent->d_seq, nd->seq)))
			return -ECHILD;

		*seqp = seq;
		status = d_revalidate(dentry, nd->flags);
		if (likely(status > 0)) {
			/*
                         * Note: do negative dentry check after revalidation in
                         * case that drops it.
                         */
			if (unlikely(negative))
				return -ENOENT;
			path->mnt = mnt;
			path->dentry = dentry;
			if (likely(__follow_mount_rcu(nd, path, inode, seqp)))
				return 1;
		}
		if (unlazy_child(nd, dentry, seq))
			return -ECHILD;
		if (unlikely(status == -ECHILD))
			/* we'd been told to redo it in non-rcu mode */
			status = d_revalidate(dentry, nd->flags);
	} else {
		dentry = __d_lookup(parent, &nd->last);
		if (unlikely(!dentry))
			return 0;
		status = d_revalidate(dentry, nd->flags);
	}
	if (unlikely(status <= 0)) {
		if (!status)
			d_invalidate(dentry);
		dput(dentry);
		return status;
	}
	if (unlikely(d_is_negative(dentry))) {
		dput(dentry);
		return -ENOENT;
	}

	path->mnt = mnt;
	path->dentry = dentry;
	err = follow_managed(path, nd);
	if (likely(err > 0))
		*inode = d_backing_inode(path->dentry);
	return err;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Al Viro
192
46.94%
13
61.90%
Nicholas Piggin
149
36.43%
1
4.76%
David Howells
27
6.60%
2
9.52%
Linus Torvalds
23
5.62%
1
4.76%
Trond Myklebust
8
1.96%
1
4.76%
Josef Bacik
7
1.71%
1
4.76%
Miklos Szeredi
2
0.49%
1
4.76%
Neil Brown
1
0.24%
1
4.76%
Total
409
100.00%
21
100.00%

/* Fast lookup failed, do it the slow way */


static struct dentry *lookup_slow(const struct qstr *name,
				  struct dentry *dir,
				  unsigned int flags)
{
	struct dentry *dentry = ERR_PTR(-ENOENT), *old;
	struct inode *inode = dir->d_inode;
	DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);

	inode_lock_shared(inode);
	/* Don't go there if it's already dead */
	if (unlikely(IS_DEADDIR(inode)))
		goto out;
again:
	dentry = d_alloc_parallel(dir, name, &wq);
	if (IS_ERR(dentry))
		goto out;
	if (unlikely(!d_in_lookup(dentry))) {
		if (!(flags & LOOKUP_NO_REVAL)) {
			int error = d_revalidate(dentry, flags);
			if (unlikely(error <= 0)) {
				if (!error) {
					d_invalidate(dentry);
					dput(dentry);
					goto again;
				}
				dput(dentry);
				dentry = ERR_PTR(error);
			}
		}
	} else {
		old = inode->i_op->lookup(inode, dentry, flags);
		d_lookup_done(dentry);
		if (unlikely(old)) {
			dput(dentry);
			dentry = old;
		}
	}
out:
	inode_unlock_shared(inode);
	return dentry;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Al Viro
205
92.34%
9
81.82%
Miklos Szeredi
16
7.21%
1
9.09%
Nicholas Piggin
1
0.45%
1
9.09%
Total
222
100.00%
11
100.00%



static inline int may_lookup(struct nameidata *nd)
{
	if (nd->flags & LOOKUP_RCU) {
		int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK);
		if (err != -ECHILD)
			return err;
		if (unlazy_walk(nd))
			return -ECHILD;
	}
	return inode_permission(nd->inode, MAY_EXEC);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Al Viro
67
100.00%
4
100.00%
Total
67
100.00%
4
100.00%



static inline int handle_dots(struct nameidata *nd, int type)
{
	if (type == LAST_DOTDOT) {
		if (!nd->root.mnt)
			set_root(nd);
		if (nd->flags & LOOKUP_RCU) {
			return follow_dotdot_rcu(nd);
		} else
			return follow_dotdot(nd);
	}
	return 0;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Al Viro
61
96.83%
3
75.00%
Eric W. Biedermann
2
3.17%
1
25.00%
Total
63
100.00%
4
100.00%



static int pick_link(struct nameidata *nd, struct path *link,
		     struct inode *inode, unsigned seq)
{
	int error;
	struct saved *last;
	if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) {
		path_to_nameidata(link, nd);
		return -ELOOP;
	}
	if (!(nd->flags & LOOKUP_RCU)) {
		if (link->mnt == nd->path.mnt)
			mntget(link->mnt);
	}
	error = nd_alloc_stack(nd);
	if (unlikely(error)) {
		if (error == -ECHILD) {
			if (unlikely(!legitimize_path(nd, link, seq))) {
				drop_links(nd);
				nd->depth = 0;
				nd->flags &= ~LOOKUP_RCU;
				nd->path.mnt = NULL;
				nd->path.dentry = NULL;
				if (!(nd->flags & LOOKUP_ROOT))
					nd->root.mnt = NULL;
				rcu_read_unlock();
			} else if (likely(unlazy_walk(nd)) == 0)
				error = nd_alloc_stack(nd);
		}
		if (error) {
			path_put(link);
			return error;
		}
	}

	last = nd->stack + nd->depth++;
	last->link = *link;
	clear_delayed_call(&last->done);
	nd->link_inode = inode;
	last->seq = seq;
	return 1;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Al Viro
261
99.62%
13
92.86%
Neil Brown
1
0.38%
1
7.14%
Total
262
100.00%
14
100.00%



enum {WALK_FOLLOW = 1, WALK_MORE = 2};

/*
 * Do we need to follow links? We _really_ want to be able
 * to do this check without having to look at inode->i_op,
 * so we keep a cache of "no, this doesn't need follow_link"
 * for the common case.
 */


static inline int step_into(struct nameidata *nd, struct path *path,
			    int flags, struct inode *inode, unsigned seq)
{
	if (!(flags & WALK_MORE) && nd->depth)
		put_link(nd);
	if (likely(!d_is_symlink(path->dentry)) ||
	   !(flags & WALK_FOLLOW || nd->flags & LOOKUP_FOLLOW)) {
		/* not a symlink or should not follow */
		path_to_nameidata(path, nd);
		nd->inode = inode;
		nd->seq = seq;
		return 0;
	}
	/* make sure that d_is_symlink above matches inode */
	if (nd->flags & LOOKUP_RCU) {
		if (read_seqcount_retry(&path->dentry->d_seq, seq))
			return -ECHILD;
	}
	return pick_link(nd, path, inode, seq);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Al Viro
119
86.23%
7
77.78%
Linus Torvalds
17
12.32%
1
11.11%
David Howells
2
1.45%
1
11.11%
Total
138
100.00%
9
100.00%



static int walk_component(struct nameidata *nd, int flags)
{
	struct path path;
	struct inode *inode;
	unsigned seq;
	int err;
	/*
         * "." and ".." are special - ".." especially so because it has
         * to be able to know about the current root directory and
         * parent relationships.
         */
	if (unlikely(nd->last_type != LAST_NORM)) {
		err = handle_dots(nd, nd->last_type);
		if (!(flags & WALK_MORE) && nd->depth)
			put_link(nd);
		return err;
	}
	err = lookup_fast(nd, &path, &inode, &seq);
	if (unlikely(err <= 0)) {
		if (err < 0)
			return err;
		path.dentry = lookup_slow(&nd->last, nd->path.dentry,
					  nd->flags);
		if (IS_ERR(path.dentry))
			return PTR_ERR(path.dentry);

		path.mnt = nd->path.mnt;
		err = follow_managed(&path, nd);
		if (unlikely(err < 0))
			return err;

		if (unlikely(d_is_negative(path.dentry))) {
			path_to_nameidata(&path, nd);
			return -ENOENT;
		}

		seq = 0;	/* we are already out of RCU mode */
		inode = d_backing_inode(path.dentry);
	}

	return step_into(nd, &path, flags, inode, seq);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Al Viro
217
91.56%
16
84.21%
Miklos Szeredi
17
7.17%
1
5.26%
Linus Torvalds
2
0.84%
1
5.26%
David Howells
1
0.42%
1
5.26%
Total
237
100.00%
19
100.00%

/*
 * We can do the critical dentry name comparison and hashing
 * operations one word at a time, but we are limited to:
 *
 * - Architectures with fast unaligned word accesses. We could
 *   do a "get_unaligned()" if this helps and is sufficiently
 *   fast.
 *
 * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we
 *   do not trap on the (extremely unlikely) case of a page
 *   crossing operation.
 *
 * - Furthermore, we need an efficient 64-bit compile for the
 *   64-bit case in order to generate the "number of bytes in
 *   the final mask". Again, that could be replaced with a
 *   efficient population count instruction or similar.
 */
#ifdef CONFIG_DCACHE_WORD_ACCESS

#include <asm/word-at-a-time.h>

#ifdef HASH_MIX

/* Architecture provides HASH_MIX and fold_hash() in <asm/hash.h> */

#elif defined(CONFIG_64BIT)
/*
 * Register pressure in the mixing function is an issue, particularly
 * on 32-bit x86, but almost any function requires one state value and
 * one temporary.  Instead, use a function designed for two state values
 * and no temporaries.
 *
 * This function cannot create a collision in only two iterations, so
 * we have two iterations to achieve avalanche.  In those two iterations,
 * we have six layers of mixing, which is enough to spread one bit's
 * influence out to 2^6 = 64 state bits.
 *
 * Rotate constants are scored by considering either 64 one-bit input
 * deltas or 64*63/2 = 2016 two-bit input deltas, and finding the
 * probability of that delta causing a change to each of the 128 output
 * bits, using a sample of random initial states.
 *
 * The Shannon entropy of the computed probabilities is then summed
 * to produce a score.  Ideally, any input change has a 50% chance of
 * toggling any given output bit.
 *
 * Mixing scores (in bits) for (12,45):
 * Input delta: 1-bit      2-bit
 * 1 round:     713.3    42542.6
 * 2 rounds:   2753.7   140389.8
 * 3 rounds:   5954.1   233458.2
 * 4 rounds:   7862.6   256672.2
 * Perfect:    8192     258048
 *            (64*128) (64*63/2 * 128)
 */

#define HASH_MIX(x, y, a)	\
	(       x ^= (a),       \
        y ^= x, x = rol64(x,12),\
        x += y, y = rol64(y,45),\
        y *= 9                  )

/*
 * Fold two longs into one 32-bit hash value.  This must be fast, but
 * latency isn't quite as critical, as there is a fair bit of additional
 * work done before the hash value is used.
 */


static inline unsigned int fold_hash(unsigned long x, unsigned long y)
{
	y ^= x * GOLDEN_RATIO_64;
	y *= GOLDEN_RATIO_64;
	return y >> 32;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
George Spelvin
31
100.00%
2
100.00%
Total
31
100.00%
2
100.00%

#else	/* 32-bit case */

/*
 * Mixing scores (in bits) for (7,20):
 * Input delta: 1-bit      2-bit
 * 1 round:     330.3     9201.6
 * 2 rounds:   1246.4    25475.4
 * 3 rounds:   1907.1    31295.1
 * 4 rounds:   2042.3    31718.6
 * Perfect:    2048      31744
 *            (32*64)   (32*31/2 * 64)
 */

#define HASH_MIX(x, y, a)	\
	(       x ^= (a),       \
        y ^= x, x = rol32(x, 7),\
        x += y, y = rol32(y,20),\
        y *= 9                  )



static inline unsigned int fold_hash(unsigned long x, unsigned long y)
{
	/* Use arch-optimized multiply if one exists */
	return __hash_32(y ^ __hash_32(x));
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
George Spelvin
28
100.00%
2
100.00%
Total
28
100.00%
2
100.00%

#endif

/*
 * Return the hash of a string of known length.  This is carfully
 * designed to match hash_name(), which is the more critical function.
 * In particular, we must end by hashing a final word containing 0..7
 * payload bytes, to match the way that hash_name() iterates until it
 * finds the delimiter after the name.
 */


unsigned int full_name_hash(const void *salt, const char *name, unsigned int len)
{
	unsigned long a, x = 0, y = (unsigned long)salt;

	for (;;) {
		if (!len)
			goto done;
		a = load_unaligned_zeropad(name);
		if (len < sizeof(unsigned long))
			break;
		HASH_MIX(x, y, a);
		name += sizeof(unsigned long);
		len -= sizeof(unsigned long);
	}
	x ^= a & bytemask_from_count(len);
done:
	return fold_hash(x, y);
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
Linus Torvalds
81
71.68%
3
37.50%
George Spelvin
28
24.78%
3
37.50%
Will Deacon
3
2.65%
1
12.50%
Al Viro
1
0.88%
1
12.50%
Total
113
100.00%
8
100.00%


EXPORT_SYMBOL(full_name_hash);

/* Return the "hash_len" (hash and length) of a null-terminated string */


u64 hashlen_string(const void *salt, const char *name)
{
	unsigned long a = 0, x = 0, y = (unsigned long)salt;
	unsigned long adata, mask, len;
	const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS;

	len = 0;
	goto inside;

	do {
		HASH_MIX(x, y, a);
		len += sizeof(unsigned long);
inside:
		a = load_unaligned_zeropad(name+len);
	} while (!has_zero(a, &adata, &constants));

	adata = prep_zero_mask(a, adata, &constants);
	mask = create_zero_mask(adata);
	x ^= a & zero_bytemask(mask);

	return hashlen_create(fold_hash(x, y), len + find_zero(mask));
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
George Spelvin
128
87.07%
2
66.67%
Linus Torvalds
19
12.93%
1
33.33%
Total
147
100.00%
3
100.00%


EXPORT_SYMBOL(hashlen_string);

/*
 * Calculate the length and hash of the path component, and
 * return the "hash_len" as the result.
 */


static inline u64 hash_name(const void *salt, const char *name)
{
	unsigned long a = 0, b, x = 0, y = (unsigned long)salt;
	unsigned long adata, bdata, mask, len;
	const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS;

	len = 0;
	goto inside;

	do {
		HASH_MIX(x, y, a);
		len += sizeof(unsigned long);
inside:
		a = load_unaligned_zeropad(name+len);
		b = a ^ REPEAT_BYTE('/');
	} while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants)));

	adata = prep_zero_mask(a, adata, &constants);
	bdata = prep_zero_mask(b, bdata, &constants);
	mask = create_zero_mask(adata | bdata);
	x ^= a & zero_bytemask(mask);

	return hashlen_create(fold_hash(x, y), len + find_zero(mask));
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Linus Torvalds
164
86.77%
7
77.78%
George Spelvin
25
13.23%
2
22.22%
Total
189
100.00%
9
100.00%

#else	/* !CONFIG_DCACHE_WORD_ACCESS: Slow, byte-at-a-time version */

/* Return the hash of a string of known length */


unsigned int full_name_hash(const void *salt, const char *name, unsigned int len)
{
	unsigned long hash = init_name_hash(salt);
	while (len--)
		hash = partial_name_hash((unsigned char)*name++, hash);
	return end_name_hash(hash);
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
Linus Torvalds
51
92.73%
2
66.67%
George Spelvin
4
7.27%
1
33.33%
Total
55
100.00%
3
100.00%


EXPORT_SYMBOL(full_name_hash);

/* Return the "hash_len" (hash and length) of a null-terminated string */


u64 hashlen_string(const void *salt, const char *name)
{
	unsigned long hash = init_name_hash(salt);
	unsigned long len = 0, c;

	c = (unsigned char)*name;
	while (c) {
		len++;
		hash = partial_name_hash(c, hash);
		c = (unsigned char)name[len];
	}
	return hashlen_create(end_name_hash(hash), len);
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
George Spelvin
73
90.12%
3
75.00%
Linus Torvalds
8
9.88%
1
25.00%
Total
81
100.00%
4
100.00%


EXPORT_SYMBOL(hashlen_string);

/*
 * We know there's a real path component here of at least
 * one character.
 */


static inline u64 hash_name(const void *salt, const char *name)
{
	unsigned long hash = init_name_hash(salt);
	unsigned long len = 0, c;

	c = (unsigned char)*name;
	do {
		len++;
		hash = partial_name_hash(c, hash);
		c = (unsigned char)name[len];
	} while (c && c != '/');
	return hashlen_create(end_name_hash(hash), len);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Linus Torvalds
89
100.00%
4
100.00%
Total
89
100.00%
4
100.00%

#endif

/*
 * Name resolution.
 * This is the basic name resolution function, turning a pathname into
 * the final dentry. We expect 'base' to be positive and a directory.
 *
 * Returns 0 and nd will have valid dentry and mnt on success.
 * Returns error and drops reference to input namei data on failure.
 */


static int link_path_walk(const char *name, struct nameidata *nd)
{
	int err;

	while (*name=='/')
		name++;
	if (!*name)
		return 0;

	/* At this point we know we have a real path component. */
	for(;;) {
		u64 hash_len;
		int type;

		err = may_lookup(nd);
		if (err)
			return err;

		hash_len = hash_name(nd->path.dentry, name);

		type = LAST_NORM;
		if (name[0] == '.') switch (hashlen_len(hash_len)) {
			case 2:
				if (name[1] == '.') {
					type = LAST_DOTDOT;
					nd->flags |= LOOKUP_JUMPED;
				}
				break;
			case 1:
				type = LAST_DOT;
		}
		if (likely(type == LAST_NORM)) {
			struct dentry *parent = nd->path.dentry;
			nd->flags &= ~LOOKUP_JUMPED;
			if (unlikely(parent->d_flags & DCACHE_OP_HASH)) {
				struct qstr this = { { .hash_len = hash_len }, .name = name };
				err = parent->d_op->d_hash(parent, &this);
				if (err < 0)
					return err;
				hash_len = this.hash_len;
				name = this.name;
			}
		}

		nd->last.hash_len = hash_len;
		nd->last.name = name;
		nd->last_type = type;

		name += hashlen_len(hash_len);
		if (!*name)
			goto OK;
		/*
                 * If it wasn't NUL, we know it was '/'. Skip that
                 * slash, and continue until no more slashes.
                 */
		do {
			name++;
		} while (unlikely(*name == '/'));
		if (unlikely(!*name)) {
OK:
			/* pathname body, done */
			if (!nd->depth)
				return 0;
			name = nd->stack[nd->depth - 1].name;
			/* trailing symlink, done */
			if (!name)
				return 0;
			/* last component of nested symlink */
			err = walk_component(nd, WALK_FOLLOW);
		} else {
			/* not the last component */
			err = walk_component(nd, WALK_FOLLOW | WALK_MORE);
		}
		if (err < 0)
			return err;

		if (err) {
			const char *s = get_link(nd);

			if (IS_ERR(s))
				return PTR_ERR(s);
			err = 0;
			if (unlikely(!s)) {
				/* jumped */
				put_link(nd);
			} else {
				nd->stack[nd->depth - 1].name = name;
				name = s;
				continue;
			}
		}
		if (unlikely(!d_can_lookup(nd->path.dentry))) {
			if (nd->flags & LOOKUP_RCU) {
				if (unlazy_walk(nd))
					return -ECHILD;
			}
			return -ENOTDIR;
		}
	}
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Al Viro
315
65.62%
23
82.14%
Nicholas Piggin
86
17.92%
1
3.57%
Linus Torvalds
77
16.04%
3
10.71%
James Hogan
2
0.42%
1
3.57%
Total
480
100.00%
28
100.00%



static const char *path_init(struct nameidata *nd, unsigned flags)
{
	const char *s = nd->name->name;

	if (!*s)
		flags &= ~LOOKUP_RCU;

	nd->last_type = LAST_ROOT; /* if there are only slashes... */
	nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT;
	nd->depth = 0;
	if (flags & LOOKUP_ROOT) {
		struct dentry *root = nd->root.dentry;
		struct inode *inode = root->d_inode;
		if (*s && unlikely(!d_can_lookup(root)))
			return ERR_PTR(-ENOTDIR);
		nd->path = nd->root;
		nd->inode = inode;
		if (flags & LOOKUP_RCU) {
			rcu_read_lock();
			nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
			nd->root_seq = nd->seq;
			nd->m_seq = read_seqbegin(&mount_lock);
		} else {
			path_get(&nd->path);
		}
		return s;
	}

	nd->root.mnt = NULL;
	nd->path.mnt = NULL;
	nd->path.dentry = NULL;

	nd->m_seq = read_seqbegin(&mount_lock);
	if (*s == '/') {
		if (flags & LOOKUP_RCU)
			rcu_read_lock();
		set_root(nd);
		if (likely(!nd_jump_root(nd)))
			return s;
		nd->root.mnt = NULL;
		rcu_read_unlock();
		return ERR_PTR(-ECHILD);
	} else if (nd->dfd == AT_FDCWD) {
		if (flags & LOOKUP_RCU) {
			struct fs_struct *fs = current->fs;
			unsigned seq;

			rcu_read_lock();

			do {
				seq = read_seqcount_begin(&fs->seq);
				nd->path = fs->pwd;
				nd->inode = nd->path.dentry->d_inode;
				nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
			} while (read_seqcount_retry(&fs->seq, seq));
		} else {
			get_fs_pwd(current->fs, &nd->path);
			nd->inode = nd->path.dentry->d_inode;
		}
		return s;
	} else {
		/* Caller must check execute permissions on the starting path component */
		struct fd f = fdget_raw(nd->dfd);
		struct dentry *dentry;

		if (!f.file)
			return ERR_PTR(-EBADF);

		dentry = f.file->f_path.dentry;

		if (*s) {
			if (!d_can_lookup(dentry)) {
				fdput(f);
				return ERR_PTR(-ENOTDIR);
			}
		}

		nd->path = f.file->f_path;
		if (flags & LOOKUP_RCU) {
			rcu_read_lock();
			nd->inode = nd->path.dentry->d_inode;
			nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
		} else {
			path_get(&nd->path);
			nd->inode = nd->path.dentry->d_inode;
		}
		fdput(f);
		return s;
	}
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Al Viro
350
63.52%
23
57.50%
Nicholas Piggin
128
23.23%
2
5.00%
Linus Torvalds (pre-git)
19
3.45%
5
12.50%
Linus Torvalds
13
2.36%
2
5.00%
Trond Myklebust
12
2.18%
1
2.50%
David Howells
10
1.81%
1
2.50%
Ulrich Drepper
8
1.45%
1
2.50%
Jan Blunck
8
1.45%
3
7.50%
Miklos Szeredi
2
0.36%
1
2.50%
Jeff Layton
1
0.18%
1
2.50%
Total
551
100.00%
40
100.00%



static const char *trailing_symlink(struct nameidata *nd)
{
	const char *s;
	int error = may_follow_link(nd);
	if (unlikely(error))
		return ERR_PTR(error);
	nd->flags |= LOOKUP_PARENT;
	nd->stack[0].name = NULL;
	s = get_link(nd);
	return s ? s : "";
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Al Viro
68
97.14%
6
85.71%
Nicholas Piggin
2
2.86%
1
14.29%
Total
70
100.00%
7
100.00%



static inline int lookup_last(struct nameidata *nd)
{
	if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len])
		nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;

	nd->flags &= ~LOOKUP_PARENT;
	return walk_component(nd, 0);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Al Viro
56
100.00%
4
100.00%
Total
56
100.00%
4
100.00%



static int handle_lookup_down(struct nameidata *nd)
{
	struct path path = nd->path;
	struct inode *inode = nd->inode;
	unsigned seq = nd->seq;
	int err;

	if (nd->flags & LOOKUP_RCU) {
		/*
                 * don't bother with unlazy_walk on failure - we are
                 * at the very beginning of walk, so we lose nothing
                 * if we simply redo everything in non-RCU mode
                 */
		if (unlikely(!__follow_mount_rcu(nd, &path, &inode, &seq)))
			return -ECHILD;
	} else {
		dget(path.dentry);
		err = follow_managed(&path, nd);
		if (unlikely(err < 0))
			return err;
		inode = d_backing_inode(path.dentry);
		seq = 0;
	}
	path_to_nameidata(&path, nd);
	nd->inode = inode;
	nd->seq = seq;
	return 0;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Al Viro
141
100.00%
1
100.00%
Total
141
100.00%
1
100.00%

/* Returns 0 and nd will be valid on success; Retuns error, otherwise. */


static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path)
{
	const char *s = path_init(nd, flags);
	int err;

	if (IS_ERR(s))
		return PTR_ERR(s);

	if (unlikely(flags & LOOKUP_DOWN)) {
		err = handle_lookup_down(nd);
		if (unlikely(err < 0)) {
			terminate_walk(nd);
			return err;
		}
	}

	while (!(err = link_path_walk(s, nd))
		&& ((err = lookup_last(nd)) > 0)) {
		s = trailing_symlink(nd);
		if (IS_ERR(s)) {
			err = PTR_ERR(s);
			break;
		}
	}
	if (!err)
		err = complete_walk(nd);

	if (!err && nd->flags & LOOKUP_DIRECTORY)
		if (!d_can_lookup(nd->path.dentry))
			err = -ENOTDIR;
	if (!err) {
		*path = nd->path;
		nd->path.mnt = NULL;
		nd->path.dentry = NULL;
	}
	terminate_walk(nd);
	return err;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Al Viro
210
97.67%
17
85.00%
David Howells
3
1.40%
1
5.00%
Miklos Szeredi
1
0.47%
1
5.00%
Kees Cook
1
0.47%
1
5.00%
Total
215
100.00%
20
100.00%



static int filename_lookup(int dfd, struct filename *name, unsigned flags,
			   struct path *path, struct path *root)
{
	int retval;
	struct nameidata nd;
	if (IS_ERR(name))
		return PTR_ERR(name);
	if (unlikely(root)) {
		nd.root = *root;
		flags |= LOOKUP_ROOT;
	}
	set_nameidata(&nd, dfd, name);
	retval = path_lookupat(&nd, flags | LOOKUP_RCU, path);
	if (unlikely(retval == -ECHILD))
		retval = path_lookupat(&nd, flags, path);
	if (unlikely(retval == -ESTALE))
		retval = path_lookupat(&nd, flags | LOOKUP_REVAL, path);

	if (likely(!retval))
		audit_inode(name, path->dentry, flags & LOOKUP_PARENT);
	restore_nameidata();
	putname(name);
	return retval;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Al Viro
113
66.86%
10
58.82%
Nicholas Piggin
37
21.89%
1
5.88%
Jeff Layton
7
4.14%
2
11.76%
Andrew Morton
6
3.55%
1
5.88%
Ulrich Drepper
3
1.78%
1
5.88%
Neil Brown
2
1.18%
1
5.88%
Hanna V. Linder
1
0.59%
1
5.88%
Total
169
100.00%
17
100.00%

/* Returns 0 and nd will be valid on success; Retuns error, otherwise. */


static int path_parentat(struct nameidata *nd, unsigned flags,
				struct path *parent)
{
	const char *s = path_init(nd, flags);
	int err;
	if (IS_ERR(s))
		return PTR_ERR(s);
	err = link_path_walk(s, nd);
	if (!err)
		err = complete_walk(nd);
	if (!err) {
		*parent = nd->path;
		nd->path.mnt = NULL;
		nd->path.dentry = NULL;
	}
	terminate_walk(nd);
	return err;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Al Viro
106
100.00%
5
100.00%
Total
106
100.00%
5
100.00%



static struct filename *filename_parentat(int dfd, struct filename *name,
				unsigned int flags, struct path *parent,
				struct qstr *last, int *type)
{
	int retval;
	struct nameidata nd;

	if (IS_ERR(name))
		return name;
	set_nameidata(&nd, dfd, name);
	retval = path_parentat(&nd, flags | LOOKUP_RCU, parent);
	if (unlikely(retval == -ECHILD))
		retval = path_parentat(&nd, flags, parent);
	if (unlikely(retval == -ESTALE))
		retval = path_parentat(&nd, flags | LOOKUP_REVAL, parent);
	if (likely(!retval)) {
		*last = nd.last;
		*type = nd.last_type;
		audit_inode(name, parent->dentry, LOOKUP_PARENT);
	} else {
		putname(name);
		name = ERR_PTR(retval);
	}
	restore_nameidata();
	return name;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Al Viro
177
100.00%
5
100.00%
Total
177
100.00%
5
100.00%

/* does lookup, returns the object with parent locked */


struct dentry *kern_path_locked(const char *name, struct path *path)
{
	struct filename *filename;
	struct dentry *d;
	struct qstr last;
	int type;

	filename = filename_parentat(AT_FDCWD, getname_kernel(name), 0, path,
				    &last, &type);
	if (IS_ERR(filename))
		return ERR_CAST(filename);
	if (unlikely(type != LAST_NORM)) {
		path_put(path);
		putname(filename);
		return ERR_PTR(-EINVAL);
	}
	inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT);
	d = __lookup_hash(&last, path->dentry, 0);
	if (IS_ERR(d)) {
		inode_unlock(path->dentry->d_inode);
		path_put(path);
	}
	putname(filename);
	return d;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Al Viro
123
80.39%
7
77.78%
Ulrich Drepper
18
11.76%
1
11.11%
Paul Moore
12
7.84%
1
11.11%
Total
153
100.00%
9
100.00%



int kern_path(const char *name, unsigned int flags, struct path *path)
{
	return filename_lookup(AT_FDCWD, getname_kernel(name),
			       flags, path, NULL);
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
Al Viro
36
100.00%
6
100.00%
Total
36
100.00%
6
100.00%


EXPORT_SYMBOL(kern_path);

/**
 * 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
 * @path: pointer to struct path to fill
 */


int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt,
		    const char *name, unsigned int flags,
		    struct path *path)
{
	struct path root = {.mnt = mnt, .dentry = dentry};
	/* the first argument of filename_lookup() is ignored with root */
	return filename_lookup(AT_FDCWD, getname_kernel(name),
			       flags , path, &root);
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
Al Viro
36
56.25%
9
90.00%
Josef 'Jeff' Sipek
28
43.75%
1
10.00%
Total
64
100.00%
10
100.00%


EXPORT_SYMBOL(vfs_path_lookup);

/**
 * 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 usage and should
 * not be called by generic code.
 *
 * The caller must hold base->i_mutex.
 */


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

	WARN_ON_ONCE(!inode_is_locked(base->d_inode));

	this.name = name;
	this.len = len;
	this.hash = full_name_hash(base, name, len);
	if (!len)
		return ERR_PTR(-EACCES);

	if (unlikely(name[0] == '.')) {
		if (len < 2 || (len == 2 && name[1] == '.'))
			return ERR_PTR(-EACCES);
	}

	while (len--) {
		c = *(const unsigned char *)name++;
		if (c == '/' || c == '\0')
			return ERR_PTR(-EACCES);
	}
	/*
         * See if the low-level filesystem might want
         * to use its own hash..
         */
	if (base->d_flags & DCACHE_OP_HASH) {
		int err = base->d_op->d_hash(base, &this);
		if (err < 0)
			return ERR_PTR(err);
	}

	err = inode_permission(base->d_inode, MAY_EXEC);
	if (err)
		return ERR_PTR(err);

	return __lookup_hash(&this, base, 0);
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
Al Viro
115
51.11%
12
57.14%
Linus Torvalds (pre-git)
42
18.67%
2
9.52%
Linus Torvalds
38
16.89%
3
14.29%
Miklos Szeredi
18
8.00%
1
4.76%
James Morris
9
4.00%
1
4.76%
Josef 'Jeff' Sipek
2
0.89%
1
4.76%
Christoph Hellwig
1
0.44%
1
4.76%
Total
225
100.00%
21
100.00%


EXPORT_SYMBOL(lookup_one_len);

/**
 * lookup_one_len_unlocked - 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 usage and should
 * not be called by generic code.
 *
 * Unlike lookup_one_len, it should be called without the parent
 * i_mutex held, and will take the i_mutex itself if necessary.
 */


struct dentry *lookup_one_len_unlocked(const char *name,
				       struct dentry *base, int len)
{
	struct qstr this;
	unsigned int c;
	int err;
	struct dentry *ret;

	this.name = name;
	this.len = len;
	this.hash = full_name_hash(base, name, len);
	if (!len)
		return ERR_PTR(-EACCES);

	if (unlikely(name[0] == '.')) {
		if (len < 2 || (len == 2 && name[1] == '.'))
			return ERR_PTR(-EACCES);
	}

	while (len--) {
		c = *(const unsigned char *)name++;
		if (c == '/' || c == '\0')
			return ERR_PTR(-EACCES);
	}
	/*
         * See if the low-level filesystem might want
         * to use its own hash..
         */
	if (base->d_flags & DCACHE_OP_HASH) {
		int err = base->d_op->d_hash(base, &this);
		if (err < 0)
			return ERR_PTR(err);
	}

	err = inode_permission(base->d_inode, MAY_EXEC);
	if (err)
		return ERR_PTR(err);

	ret = lookup_dcache(&this, base, 0);
	if (!ret)
		ret = lookup_slow(&this, base, 0);
	return ret;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
Al Viro
94
39.17%
3
25.00%
Linus Torvalds
68
28.33%
4
33.33%
Linus Torvalds (pre-git)
44
18.33%
2
16.67%
Miklos Szeredi
24
10.00%
1
8.33%
James Morris
9
3.75%
1
8.33%
Neil Brown
1
0.42%
1
8.33%
Total
240
100.00%
12
100.00%


EXPORT_SYMBOL(lookup_one_len_unlocked);

#ifdef CONFIG_UNIX98_PTYS


int path_pts(struct path *path)
{
	/* Find something mounted on "pts" in the same directory as
         * the input path.
         */
	struct dentry *child, *parent;
	struct qstr this;
	int ret;

	ret = path_parent_directory(path);
	if (ret)
		return ret;

	parent = path->dentry;
	this.name = "pts";
	this.len = 3;
	child = d_hash_and_lookup(parent, &this);
	if (!child)
		return -ENOENT;

	path->dentry = child;
	dput(parent);
	follow_mount(path);
	return 0;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
Eric W. Biedermann
96
100.00%
1
100.00%
Total
96
100.00%
1
100.00%

#endif



int user_path_at_empty(int dfd, const char __user *name, unsigned flags,
		 struct path *path, int *empty)
{
	return filename_lookup(dfd, getname_flags(name, flags, empty),
			       flags, path, NULL);
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
Linus Torvalds (pre-git)
21
44.68%
6
42.86%
Al Viro
13
27.66%
5
35.71%
Andy Whitcroft
7
14.89%
1
7.14%
Ulrich Drepper
5
10.64%
1
7.14%
Linus Torvalds
1
2.13%
1
7.14%
Total
47
100.00%
14
100.00%


EXPORT_SYMBOL(user_path_at_empty);

/**
 * mountpoint_last - look up last component for umount
 * @nd:   pathwalk nameidata - currently pointing at parent directory of "last"
 *
 * This is a special lookup_last function just for umount. In this case, we
 * need to resolve the path without doing any revalidation.
 *
 * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since
 * mountpoints are always pinned in the dcache, their ancestors are too. Thus,
 * in almost all cases, this lookup will be served out of the dcache. The only
 * cases where it won't are if nd->last refers to a symlink or the path is
 * bogus and it doesn't exist.
 *
 * Returns:
 * -error: if there was an error during lookup. This includes -ENOENT if the
 *         lookup found a negative dentry.
 *
 * 0:      if we successfully resolved nd->last and found it to not to be a
 *         symlink that needs to be followed.
 *
 * 1:      if we successfully resolved nd->last and found it to be a symlink
 *         that needs to be followed.
 */

static int

mountpoint_last(struct nameidata *nd)
{
	int error = 0;
	struct dentry *dir = nd->path.dentry;
	struct path path;

	/* If we're in rcuwalk, drop out of it to handle last component */
	if (nd->flags & LOOKUP_RCU) {
		if (unlazy_walk(nd))
			return -ECHILD;
	}

	nd->flags &= ~LOOKUP_PARENT;

	if (unlikely(nd->last_type != LAST_NORM)) {
		error = handle_dots(nd, nd->last_type);
		if (error)
			return error;
		path.dentry = dget(nd->path.dentry);
	} else {
		path.dentry = d_lookup(dir, &nd->last);
		if (!path.dentry) {
			/*
                         * No cached dentry. Mounted dentries are pinned in the
                         * cache, so that means that this dentry is probably
                         * a symlink or the path doesn't actually point
                         * to a mounted dentry.
                         */
			path.dentry = lookup_slow(&nd->last, dir,
					     nd->flags | LOOKUP_NO_REVAL);
			if (IS_ERR(path.dentry))
				return PTR_ERR(path.dentry);
		}
	}
	if (d_is_negative(path.dentry)) {
		dput(path.dentry);
		return -ENOENT;
	}
	path.mnt = nd->path.mnt;
	return step_into(nd, &path, 0, d_backing_inode(path.dentry), 0);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Jeff Layton
141
64.09%
1
7.69%
Al Viro
78
35.45%
11
84.62%
Dave Jones
1
0.45%
1
7.69%
Total
220
100.00%
13
100.00%

/**
 * path_mountpoint - look up a path to be umounted
 * @nd:         lookup context
 * @flags:      lookup flags
 * @path:       pointer to container for result
 *
 * Look up the given name, but don't attempt to revalidate the last component.
 * Returns 0 and "path" will be valid on success; Returns error otherwise.
 */

static int

path_mountpoint(struct nameidata *nd, unsigned flags, struct path *path)
{
	const char *s = path_init(nd, flags);
	int err;
	if (IS_ERR(s))
		return PTR_ERR(s);
	while (!(err = link_path_walk(s, nd)) &&
		(err = mountpoint_last(nd)) > 0) {
		s = trailing_symlink(nd);
		if (IS_ERR(s)) {
			err = PTR_ERR(s);
			break;
		}
	}
	if (!err) {
		*path = nd->path;
		nd->path.mnt = NULL;
		nd->path.dentry = NULL;
		follow_mount(path);
	}
	terminate_walk(nd);
	return err;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Al Viro
107
75.89%
10
90.91%
Jeff Layton
34
24.11%
1
9.09%
Total
141
100.00%
11
100.00%


static int

filename_mountpoint(int dfd, struct filename *name, struct path *path,
			unsigned int flags)
{
	struct nameidata nd;
	int error;
	if (IS_ERR(name))
		return PTR_ERR(name);
	set_nameidata(&nd, dfd, name);
	error = path_mountpoint(&nd, flags | LOOKUP_RCU, path);
	if (unlikely(error == -ECHILD))
		error = path_mountpoint(&nd, flags, path);
	if (unlikely(error == -ESTALE))
		error = path_mountpoint(&nd, flags | LOOKUP_REVAL, path);
	if (likely(!error))
		audit_inode(name, path->dentry, 0);
	restore_nameidata();
	putname(name);
	return error;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Jeff Layton
72
50.35%
1
11.11%
Al Viro
71
49.65%
8
88.89%
Total
143
100.00%
9
100.00%

/**
 * user_path_mountpoint_at - lookup a path from userland in order to umount it
 * @dfd:        directory file descriptor
 * @name:       pathname from userland
 * @flags:      lookup flags
 * @path:       pointer to container to hold result
 *
 * A umount is a special case for path walking. We're not actually interested
 * in the inode in this situation, and ESTALE errors can be a problem. We
 * simply want track down the dentry and vfsmount attached at the mountpoint
 * and avoid revalidating the last component.
 *
 * Returns 0 and populates "path" on success.
 */

int

user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags,
			struct path *path)
{
	return filename_mountpoint(dfd, getname(name), path, flags);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Al Viro
36
94.74%
2
66.67%
Jeff Layton
2
5.26%
1
33.33%
Total
38
100.00%
3
100.00%


int

kern_path_mountpoint(int dfd, const char *name, struct path *path,
			unsigned int flags)
{
	return filename_mountpoint(dfd, getname_kernel(name), path, flags);
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
Al Viro
37
100.00%
2
100.00%
Total
37
100.00%
2
100.00%


EXPORT_SYMBOL(kern_path_mountpoint);



int __check_sticky(struct inode *dir, struct inode *inode)
{
	kuid_t fsuid = current_fsuid();

	if (uid_eq(inode->i_uid, fsuid))
		return 0;
	if (uid_eq(dir->i_uid, fsuid))
		return 0;
	return !capable_wrt_inode_uidgid(inode, CAP_FOWNER);
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
Linus Torvalds (pre-git)
38
65.52%
1
16.67%
Eric W. Biedermann
8
13.79%
1
16.67%
Serge E. Hallyn
5
8.62%
1
16.67%
David Howells
5
8.62%
1
16.67%
Andrew Lutomirski
1
1.72%
1
16.67%
Miklos Szeredi
1
1.72%
1
16.67%
Total
58
100.00%
6
100.00%


EXPORT_SYMBOL(__check_sticky);

/*
 *      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 the victim has an unknown uid or gid we can't change the inode.
 *  8. If we were asked to remove a directory and victim isn't one - ENOTDIR.
 *  9. If we were asked to remove a non-directory and victim isn't one - EISDIR.
 * 10. We can't remove a root or mountpoint.
 * 11. We don't allow removal of NFS sillyrenamed files; it's handled by
 *     nfs_async_unlink().
 */


static int may_delete(struct inode *dir, struct dentry *victim, bool isdir)
{
	struct inode *inode = d_backing_inode(victim);
	int error;

	if (d_is_negative(victim))
		return -ENOENT;
	BUG_ON(!inode);

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

	error = inode_permission(dir, MAY_WRITE | MAY_EXEC);
	if (error)
		return error;
	if (IS_APPEND(dir))
		return -EPERM;

	if (check_sticky(dir, inode) || IS_APPEND(inode) ||
	    IS_IMMUTABLE(inode) || IS_SWAPFILE(inode) || HAS_UNMAPPED_ID(inode))
		return -EPERM;
	if (isdir) {
		if (!d_is_dir(victim))
			return -ENOTDIR;
		if (IS_ROOT(victim))
			return -EBUSY;
	} else if (d_is_dir(victim))
		return -EISDIR;
	if (IS_DEADDIR(dir))
		return -ENOENT;
	if (victim->d_flags & DCACHE_NFSFS_RENAMED)
		return -EBUSY;
	return 0;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Linus Torvalds (pre-git)
121
61.11%
1
7.69%
David Howells
24
12.12%
2
15.38%
Al Viro
12
6.06%
2
15.38%
Frank Cusack
12
6.06%
1
7.69%
Christoph Hellwig
9
4.55%
1
7.69%
Eric W. Biedermann
5
2.53%
1
7.69%
Amy Griffis
5
2.53%
1
7.69%
Jeff Layton
4
2.02%
2
15.38%
Hugh Dickins
4
2.02%
1
7.69%
Miklos Szeredi
2
1.01%
1
7.69%
Total
198
100.00%
13
100.00%

/*      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 can't do it if the fs can't represent the fsuid or fsgid.
 *  4. We should have write and exec permissions on dir
 *  5. We can't do it if dir is immutable (done in permission())
 */


static inline int may_create(struct inode *dir, struct dentry *child)
{
	struct user_namespace *s_user_ns;
	audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE);
	if (child->d_inode)
		return -EEXIST;
	if (IS_DEADDIR(dir))
		return -ENOENT;
	s_user_ns = dir->i_sb->s_user_ns;
	if (!kuid_has_mapping(s_user_ns, current_fsuid()) ||
	    !kgid_has_mapping(s_user_ns, current_fsgid()))
		return -EOVERFLOW;
	return inode_permission(dir, MAY_WRITE | MAY_EXEC);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Linus Torvalds (pre-git)
47
50.00%
2
40.00%
Eric W. Biedermann
37
39.36%
1
20.00%
Jeff Layton
9
9.57%
1
20.00%
Al Viro
1
1.06%
1
20.00%
Total
94
100.00%
5
100.00%

/*
 * 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) {
		inode_lock_nested(p1->d_inode, I_MUTEX_PARENT);
		return NULL;
	}

	mutex_lock(&p1->d_sb->s_vfs_rename_mutex);

	p = d_ancestor(p2, p1);
	if (p) {
		inode_lock_nested(p2->d_inode, I_MUTEX_PARENT);
		inode_lock_nested(p1->d_inode, I_MUTEX_CHILD);
		return p;
	}

	p = d_ancestor(p1, p2);
	if (p) {
		inode_lock_nested(p1->d_inode, I_MUTEX_PARENT);
		inode_lock_nested(p2->d_inode, I_MUTEX_CHILD);
		return p;
	}

	inode_lock_nested(p1->d_inode, I_MUTEX_PARENT);
	inode_lock_nested(p2->d_inode, I_MUTEX_PARENT2);
	return NULL;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
Al Viro
106
73.10%
3
33.33%
Hirofumi Ogawa
14
9.66%
2
22.22%
Ingo Molnar
12
8.28%
1
11.11%
Nicholas Piggin
10
6.90%
1
11.11%
Arjan van de Ven
2
1.38%
1
11.11%
Miklos Szeredi
1
0.69%
1
11.11%
Total
145
100.00%
9
100.00%


EXPORT_SYMBOL(lock_rename);



void unlock_rename(struct dentry *p1, struct dentry *p2)
{
	inode_unlock(p1->d_inode);
	if (p1 != p2) {
		inode_unlock(p2->d_inode);
		mutex_unlock(&p1->d_sb->s_vfs_rename_mutex);
	}
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
Nicholas Piggin
44
93.62%
1
33.33%
Al Viro
3
6.38%
2
66.67%
Total
47
100.00%
3
100.00%


EXPORT_SYMBOL(unlock_rename);



int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
		bool want_excl)
{
	int error = may_create(dir, dentry);
	if (error)
		return error;

	if (!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;
	error = dir->i_op->create(dir, dentry, mode, want_excl);
	if (!error)
		fsnotify_create(dir, dentry);
	return error;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
Nicholas Piggin
100
90.91%
1
20.00%
Al Viro
9
8.18%
3
60.00%
Ingo Molnar
1
0.91%
1
20.00%
Total
110
100.00%
5
100.00%


EXPORT_SYMBOL(vfs_create);



bool may_open_dev(const struct path *path)
{
	return !(path->mnt->mnt_flags & MNT_NODEV) &&
		!(path->mnt->mnt_sb->s_iflags & SB_I_NODEV);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Eric W. Biedermann
36
100.00%
1
100.00%
Total
36
100.00%
1
100.00%



static int may_open(const struct path *path, int acc_mode, int flag)
{
	struct dentry *dentry = path->dentry;
	struct inode *inode = dentry->d_inode;
	int error;

	if (!inode)
		return -ENOENT;

	switch (inode->i_mode & S_IFMT) {
	case S_IFLNK:
		return -ELOOP;
	case S_IFDIR:
		if (acc_mode & MAY_WRITE)
			return -EISDIR;
		break;
	case S_IFBLK:
	case S_IFCHR:
		if (!may_open_dev(path))
			return -EACCES;
		/*FALLTHRU*/
	case S_IFIFO:
	case S_IFSOCK:
		flag &= ~O_TRUNC;
		break;
	}

	error = inode_permission(inode, MAY_OPEN | acc_mode);
	if (error)
		return error;

	/*
         * An append-only file must be opened in append mode for writing.
         */
	if (IS_APPEND(inode)) {
		if  ((flag & O_ACCMODE) != O_RDONLY && !(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 && !inode_owner_or_capable(inode))
		return -EPERM;

	return 0;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Nicholas Piggin
159
84.13%
1
12.50%
Al Viro
24
12.70%
4
50.00%
Eric W. Biedermann
4
2.12%
1
12.50%
Serge E. Hallyn
1
0.53%
1
12.50%
J. Bruce Fields
1
0.53%
1
12.50%
Total
189
100.00%
8
100.00%



static int handle_truncate(struct file *filp)
{
	const struct path *path = &filp->f_path;
	struct inode *inode = path->dentry->d_inode;
	int error = get_write_access(inode);
	if (error)
		return error;
	/*
         * Refuse to truncate files with mandatory locks held on them.
         */
	error = locks_verify_locked(filp);
	if (!error)
		error = security_path_truncate(path);
	if (!error) {
		error = do_truncate(path->dentry, 0,
				    ATTR_MTIME|ATTR_CTIME|ATTR_OPEN,
				    filp);
	}
	put_write_access(inode);
	return error;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Nicholas Piggin
39
38.24%
1
9.09%
Linus Torvalds (pre-git)
34
33.33%
3
27.27%
Jeff Layton
14
13.73%
2
18.18%
Stephen D. Smalley
5
4.90%
1
9.09%
Al Viro
5
4.90%
2
18.18%
Greg Kroah-Hartman
4
3.92%
1
9.09%
Trond Myklebust
1
0.98%
1
9.09%
Total
102
100.00%
11
100.00%



static inline int open_to_namei_flags(int flag)
{
	if ((flag & O_ACCMODE) == 3)
		flag--;
	return flag;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Al Viro
14
53.85%
3
60.00%
Nicholas Piggin
11
42.31%
1
20.00%
Linus Torvalds (pre-git)
1
3.85%
1
20.00%
Total
26
100.00%
5
100.00%



static int may_o_create(const struct path *dir, struct dentry *dentry, umode_t mode)
{
	struct user_namespace *s_user_ns;
	int error = security_path_mknod(dir, dentry, mode, 0);
	if (error)
		return error;

	s_user_ns = dir->dentry->d_sb->s_user_ns;
	if (!kuid_has_mapping(s_user_ns, current_fsuid()) ||
	    !kgid_has_mapping(s_user_ns, current_fsgid()))
		return -EOVERFLOW;

	error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC);
	if (error)
		return error;

	return security_inode_create(dir->dentry->d_inode, dentry, mode);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Miklos Szeredi
76
65.52%
1
33.33%
Seth Forshee
39
33.62%
1
33.33%
Al Viro
1
0.86%
1
33.33%
Total
116
100.00%
3
100.00%

/*
 * Attempt to atomically look up, create and open a file from a negative
 * dentry.
 *
 * Returns 0 if successful.  The file will have been created and attached to
 * @file by the filesystem calling finish_open().
 *
 * Returns 1 if the file was looked up only or didn't need creating.  The
 * caller will need to perform the open themselves.  @path will have been
 * updated to point to the new dentry.  This may be negative.
 *
 * Returns an error code otherwise.
 */


static int atomic_open(struct nameidata *nd, struct dentry *dentry,
			struct path *path, struct file *file,
			const struct open_flags *op,
			int open_flag, umode_t mode,
			int *opened)
{
	struct dentry *const DENTRY_NOT_SET = (void *) -1UL;
	struct inode *dir =  nd->path.dentry->d_inode;
	int error;

	if (!(~open_flag & (O_EXCL | O_CREAT)))	/* both O_EXCL and O_CREAT */
		open_flag &= ~O_TRUNC;

	if (nd->flags & LOOKUP_DIRECTORY)
		open_flag |= O_DIRECTORY;

	file->f_path.dentry = DENTRY_NOT_SET;
	file->f_path.mnt = nd->path.mnt;
	error = dir->i_op->atomic_open(dir, dentry, file,
				       open_to_namei_flags(open_flag),
				       mode, opened);
	d_lookup_done(dentry);
	if (!error) {
		/*
                 * We didn't have the inode before the open, so check open
                 * permission here.
                 */
		int acc_mode = op->acc_mode;
		if (*opened & FILE_CREATED) {
			WARN_ON(!(open_flag & O_CREAT));
			fsnotify_create(dir, dentry);
			acc_mode = 0;
		}
		error = may_open(&file->f_path, acc_mode, open_flag);
		if (WARN_ON(error > 0))
			error = -EINVAL;
	} else if (error > 0) {
		if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) {
			error = -EIO;
		} else {
			if (file->f_path.dentry) {
				dput(dentry);
				dentry = file->f_path.dentry;
			}
			if (*opened & FILE_CREATED)
				fsnotify_create(dir, dentry);
			if (unlikely(d_is_negative(dentry))) {
				error = -ENOENT;
			} else {
				path->dentry = dentry;
				path->mnt = nd->path.mnt;
				return 1;
			}
		}
	}
	dput(dentry);
	return error;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Al Viro
173
50.73%
12
75.00%
Miklos Szeredi
165
48.39%
3
18.75%
Sage Weil
3
0.88%
1
6.25%
Total
341
100.00%
16
100.00%

/*
 * Look up and maybe create and open the last component.
 *
 * Must be called with i_mutex held on parent.
 *
 * Returns 0 if the file was successfully atomically created (if necessary) and
 * opened.  In this case the file will be returned attached to @file.
 *
 * Returns 1 if the file was not completely opened at this time, though lookups
 * and creations will have been performed and the dentry returned in @path will
 * be positive upon return if O_CREAT was specified.  If O_CREAT wasn't
 * specified then a negative dentry may be returned.
 *
 * An error code is returned otherwise.
 *
 * FILE_CREATE will be set in @*opened if the dentry was created and will be
 * cleared otherwise prior to returning.
 */


static int lookup_open(struct nameidata *nd, struct path *path,
			struct file *file,
			const struct open_flags *op,
			bool got_write, int *opened)
{
	struct dentry *dir = nd->path.dentry;
	struct inode *dir_inode = dir->d_inode;
	int open_flag = op->open_flag;
	struct dentry *dentry;
	int error, create_error = 0;
	umode_t mode = op->mode;
	DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);

	if (unlikely(IS_DEADDIR(dir_inode)))
		return -ENOENT;

	*opened &= ~FILE_CREATED;
	dentry = d_lookup(dir, &nd->last);
	for (;;) {
		if (!dentry) {
			dentry = d_alloc_parallel(dir, &nd->last, &wq);
			if (IS_ERR(dentry))
				return PTR_ERR(dentry);
		}
		if (d_in_lookup(dentry))
			break;

		error = d_revalidate(dentry, nd->flags);
		if (likely(error > 0))
			break;
		if (error)
			goto out_dput;
		d_invalidate(dentry);
		dput(dentry);
		dentry = NULL;
	}
	if (dentry->d_inode) {
		/* Cached positive dentry: will open in f_op->open */
		goto out_no_open;
	}

	/*
         * Checking write permission is tricky, bacuse we don't know if we are
         * going to actually need it: O_CREAT opens should work as long as the
         * file exists.  But checking existence breaks atomicity.  The trick is
         * to check access and if not granted clear O_CREAT from the flags.
         *
         * Another problem is returing the "right" error value (e.g. for an
         * O_EXCL open we want to return EEXIST not EROFS).
         */
	if (open_flag & O_CREAT) {
		if (!IS_POSIXACL(dir->d_inode))
			mode &= ~current_umask();
		if (unlikely(!got_write)) {
			create_error = -EROFS;
			open_flag &= ~O_CREAT;
			if (open_flag & (O_EXCL | O_TRUNC))
				goto no_open;
			/* No side effects, safe to clear O_CREAT */
		} else {
			create_error = may_o_create(&nd->path, dentry, mode);
			if (create_error) {
				open_flag &= ~O_CREAT;
				if (open_flag & O_EXCL)
					goto no_open;
			}
		}
	} else if ((open_flag & (O_TRUNC|O_WRONLY|O_RDWR)) &&
		   unlikely(!got_write)) {
		/*
                 * No O_CREATE -> atomicity not a requirement -> fall
                 * back to lookup + open
                 */
		goto no_open;
	}

	if (dir_inode->i_op->atomic_open) {
		error = atomic_open(nd, dentry, path, file, op, open_flag,
				    mode, opened);
		if (unlikely(error == -ENOENT) && create_error)
			error = create_error;
		return error;
	}

no_open:
	if (d_in_lookup(dentry)) {
		struct dentry *res = dir_inode->i_op->lookup(dir_inode, dentry,
							     nd->flags);
		d_lookup_done(dentry);
		if (unlikely(res)) {
			if (IS_ERR(res)) {
				error = PTR_ERR(res);
				goto out_dput;
			}
			dput(dentry);
			dentry = res;
		}
	}

	/* Negative dentry, just create the file */
	if (!dentry->d_inode && (open_flag & O_CREAT)) {
		*opened |= FILE_CREATED;
		audit_inode_child(dir_inode, dentry, AUDIT_TYPE_CHILD_CREATE);
		if (!dir_inode->i_op->create) {
			error = -EACCES;
			goto out_dput;
		}
		error = dir_inode->i_op->create(dir_inode, dentry, mode,
						open_flag & O_EXCL);
		if (error)
			goto out_dput;
		fsnotify_create(dir_inode, dentry);
	}
	if (unlikely(create_error) && !dentry->d_inode) {
		error = create_error;
		goto out_dput;
	}
out_no_open:
	path->dentry = dentry;
	path->mnt = nd->path.mnt;
	return 1;

out_dput:
	dput(dentry);
	return error;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Al Viro
352
58.57%
12
70.59%
Miklos Szeredi
249
41.43%
5
29.41%
Total
601
100.00%
17
100.00%

/*
 * Handle the last step of open()
 */


static int do_last(struct nameidata *nd,
		   struct file *file, const struct open_flags *op,
		   int *opened)
{
	struct dentry *dir = nd->path.dentry;
	int open_flag = op->open_flag;
	bool will_truncate = (open_flag & O_TRUNC) != 0;
	bool got_write = false;
	int acc_mode = op->acc_mode;
	unsigned seq;
	struct inode *inode;
	struct path path;
	int error;

	nd->flags &= ~LOOKUP_PARENT;
	nd->flags |= op->intent;

	if (nd->last_type != LAST_NORM) {
		error = handle_dots(nd, nd->last_type);
		if (unlikely(error))
			return error;
		goto finish_open;
	}

	if (!(open_flag & O_CREAT)) {
		if (nd->last.name[nd->last.len])
			nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
		/* we _can_ be in RCU mode here */
		error = lookup_fast(nd, &path, &inode, &seq);
		if (likely(error > 0))
			goto finish_lookup;

		if (error < 0)
			return error;

		BUG_ON(nd->inode != dir->d_inode);
		BUG_ON(nd->flags & LOOKUP_RCU);
	} else {
		/* create side of things */
		/*
                 * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED
                 * has been cleared when we got to the last component we are
                 * about to look up
                 */
		error = complete_walk(nd);
		if (error)
			return error;

		audit_inode(nd->name, dir, LOOKUP_PARENT);
		/* trailing slashes? */
		if (unlikely(nd->last