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Commit eead1911 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Linus Torvalds
Browse files

partially fix up the lookup_one_noperm mess 



Try to fix the mess created by sysfs braindamage.

 - refactor code internal to fs/namei.c a little to avoid too much
   duplication:
	o __lookup_hash_kern is renamed back to __lookup_hash
	o the old __lookup_hash goes away, permission checks moves to
	  the two callers
	o useless inline qualifiers on above functions go away
 - lookup_one_len_kern loses it's last argument and is renamed to
   lookup_one_noperm to make it's useage a little more clear
 - added kerneldoc comments to describe lookup_one_len aswell as
   lookup_one_noperm and make it very clear that no one should use
   the latter ever.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Cc: Josef 'Jeff' Sipek <jsipek@cs.sunysb.edu>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent ebb3e820

fs/namei.c

+36 −22
Original line number Diff line number Diff line
@@ -1273,7 +1273,8 @@ int __user_path_lookup_open(const char __user *name, unsigned int lookup_flags, 
	return err;

}



static inline struct dentry *__lookup_hash_kern(struct qstr *name, struct dentry *base, struct nameidata *nd)

static struct dentry *__lookup_hash(struct qstr *name,

		struct dentry *base, struct nameidata *nd)

{

	struct dentry *dentry;

	struct inode *inode;
@@ -1313,31 +1314,18 @@ out: 
 * needs parent already locked. Doesn't follow mounts.

 * SMP-safe.

 */

static inline struct dentry * __lookup_hash(struct qstr *name, struct dentry *base, struct nameidata *nd)

static struct dentry *lookup_hash(struct nameidata *nd)

{

	struct dentry *dentry;

	struct inode *inode;

	int err;



	inode = base->d_inode;



	err = permission(inode, MAY_EXEC, nd);

	dentry = ERR_PTR(err);

	err = permission(nd->dentry->d_inode, MAY_EXEC, nd);

	if (err)

		goto out;



	dentry = __lookup_hash_kern(name, base, nd);

out:

	return dentry;

}



static struct dentry *lookup_hash(struct nameidata *nd)

{

		return ERR_PTR(err);

	return __lookup_hash(&nd->last, nd->dentry, nd);

}



/* SMP-safe */

static inline int __lookup_one_len(const char *name, struct qstr *this, struct dentry *base, int len)

static int __lookup_one_len(const char *name, struct qstr *this,

		struct dentry *base, int len)

{

	unsigned long hash;

	unsigned int c;
@@ -1358,26 +1346,52 @@ static inline int __lookup_one_len(const char *name, struct qstr *this, struct d 
	return 0;

}



/**

 * lookup_one_len:  filesystem helper to lookup single pathname component

 * @name:	pathname component to lookup

 * @base:	base directory to lookup from

 * @len:	maximum length @len should be interpreted to

 *

 * Note that this routine is purely a helper for filesystem useage and should

 * not be called by generic code.  Also note that by using this function to

 * nameidata argument is passed to the filesystem methods and a filesystem

 * using this helper needs to be prepared for that.

 */

struct dentry *lookup_one_len(const char *name, struct dentry *base, int len)

{

	int err;

	struct qstr this;



	err = __lookup_one_len(name, &this, base, len);

	if (err)

		return ERR_PTR(err);



	err = permission(base->d_inode, MAY_EXEC, NULL);

	if (err)

		return ERR_PTR(err);

	return __lookup_hash(&this, base, NULL);

}



struct dentry *lookup_one_len_kern(const char *name, struct dentry *base, int len)

/**

 * lookup_one_noperm - bad hack for sysfs

 * @name:	pathname component to lookup

 * @base:	base directory to lookup from

 *

 * This is a variant of lookup_one_len that doesn't perform any permission

 * checks.   It's a horrible hack to work around the braindead sysfs

 * architecture and should not be used anywhere else.

 *

 * DON'T USE THIS FUNCTION EVER, thanks.

 */

struct dentry *lookup_one_noperm(const char *name, struct dentry *base)

{

	int err;

	struct qstr this;



	err = __lookup_one_len(name, &this, base, len);

	err = __lookup_one_len(name, &this, base, strlen(name));

	if (err)

		return ERR_PTR(err);

	return __lookup_hash_kern(&this, base, NULL);

	return __lookup_hash(&this, base, NULL);

}



int fastcall __user_walk_fd(int dfd, const char __user *name, unsigned flags,

fs/sysfs/dir.c

+1 −2
Original line number Diff line number Diff line
@@ -112,8 +112,7 @@ struct dentry *sysfs_get_dentry(struct sysfs_dirent *sd) 
		/* look it up */

		parent = dentry;

		mutex_lock(&parent->d_inode->i_mutex);

		dentry = lookup_one_len_kern(cur->s_name, parent,

					     strlen(cur->s_name));

		dentry = lookup_one_noperm(cur->s_name, parent);

		mutex_unlock(&parent->d_inode->i_mutex);

		dput(parent);

include/linux/namei.h

+2 −2
Original line number Diff line number Diff line
@@ -82,7 +82,7 @@ extern struct file *nameidata_to_filp(struct nameidata *nd, int flags); 
extern void release_open_intent(struct nameidata *);



extern struct dentry *lookup_one_len(const char *, struct dentry *, int);

extern struct dentry *lookup_one_len_kern(const char *, struct dentry *, int);

extern struct dentry *lookup_one_noperm(const char *, struct dentry *);



extern int follow_down(struct vfsmount **, struct dentry **);

extern int follow_up(struct vfsmount **, struct dentry **);