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: Miklos Szeredi <mszeredi@redhat.com>
diff --git a/fs/namei.c b/fs/namei.c
index adb0414..8a2c295 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -4677,6 +4677,31 @@
}
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 */
const char *page_get_link(struct dentry *dentry, struct inode *inode,
struct delayed_call *callback)
