security: new security_inode_init_security API adds function callback

This patch changes the security_inode_init_security API by adding a
filesystem specific callback to write security extended attributes.
This change is in preparation for supporting the initialization of
multiple LSM xattrs and the EVM xattr.  Initially the callback function
walks an array of xattrs, writing each xattr separately, but could be
optimized to write multiple xattrs at once.

For existing security_inode_init_security() calls, which have not yet
been converted to use the new callback function, such as those in
reiserfs and ocfs2, this patch defines security_old_inode_init_security().

Signed-off-by: Mimi Zohar <zohar@us.ibm.com>

fs/ext2/xattr_security.c

@@ -46,26 +46,28 @@ ext2_xattr_security_set(struct dentry *dentry, const char *name,
 			      value, size, flags);
 }
 
+int ext2_initxattrs(struct inode *inode, const struct xattr *xattr_array,
+		    void *fs_info)
+{
+	const struct xattr *xattr;
+	int err = 0;
+
+	for (xattr = xattr_array; xattr->name != NULL; xattr++) {
+		err = ext2_xattr_set(inode, EXT2_XATTR_INDEX_SECURITY,
+				     xattr->name, xattr->value,
+				     xattr->value_len, 0);
+		if (err < 0)
+			break;
+	}
+	return err;
+}
+
 int
 ext2_init_security(struct inode *inode, struct inode *dir,
 		   const struct qstr *qstr)
 {
-	int err;
-	size_t len;
-	void *value;
-	char *name;
-
-	err = security_inode_init_security(inode, dir, qstr, &name, &value, &len);
-	if (err) {
-		if (err == -EOPNOTSUPP)
-			return 0;
-		return err;
-	}
-	err = ext2_xattr_set(inode, EXT2_XATTR_INDEX_SECURITY,
-			     name, value, len, 0);
-	kfree(name);
-	kfree(value);
-	return err;
+	return security_inode_init_security(inode, dir, qstr,
+					    &ext2_initxattrs, NULL);
 }
 
 const struct xattr_handler ext2_xattr_security_handler = {