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Commit d60874cd authored by Miklos Szeredi's avatar Miklos Szeredi
Browse files

vfs: add vfs_get_link() helper 



This helper is for filesystems that want to read the symlink and are better
off with the get_link() interface (returning a char *) rather than the
readlink() interface (copy into a userspace buffer).

Also call the LSM hook for readlink (not get_link) since this is for
symlink reading not following.

Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
parent 78a3fa4f

fs/namei.c

+25 −0
Original line number Original line Diff line number Diff line
@@ -4677,6 +4677,31 @@ int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 
}

}

EXPORT_SYMBOL(generic_readlink);

EXPORT_SYMBOL(generic_readlink);





/**

 * vfs_get_link - get symlink body

 * @dentry: dentry on which to get symbolic link

 * @done: caller needs to free returned data with this

 *

 * Calls security hook and i_op->get_link() on the supplied inode.

 *

 * It does not touch atime.  That's up to the caller if necessary.

 *

 * Does not work on "special" symlinks like /proc/$$/fd/N

 */

const char *vfs_get_link(struct dentry *dentry, struct delayed_call *done)

{

	const char *res = ERR_PTR(-EINVAL);

	struct inode *inode = d_inode(dentry);



	if (d_is_symlink(dentry)) {

		res = ERR_PTR(security_inode_readlink(dentry));

		if (!res)

			res = inode->i_op->get_link(dentry, inode, done);

	}

	return res;

}

EXPORT_SYMBOL(vfs_get_link);



/* get the link contents into pagecache */

/* get the link contents into pagecache */

const char *page_get_link(struct dentry *dentry, struct inode *inode,

const char *page_get_link(struct dentry *dentry, struct inode *inode,

			  struct delayed_call *callback)

			  struct delayed_call *callback)

include/linux/fs.h

+1 −0
Original line number Original line Diff line number Diff line
@@ -2919,6 +2919,7 @@ extern int vfs_stat(const char __user *, struct kstat *); 
extern int vfs_lstat(const char __user *, struct kstat *);

extern int vfs_lstat(const char __user *, struct kstat *);

extern int vfs_fstat(unsigned int, struct kstat *);

extern int vfs_fstat(unsigned int, struct kstat *);

extern int vfs_fstatat(int , const char __user *, struct kstat *, int);

extern int vfs_fstatat(int , const char __user *, struct kstat *, int);

extern const char *vfs_get_link(struct dentry *, struct delayed_call *);





extern int __generic_block_fiemap(struct inode *inode,

extern int __generic_block_fiemap(struct inode *inode,

				  struct fiemap_extent_info *fieinfo,

				  struct fiemap_extent_info *fieinfo,