From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752129AbcA0BCJ (ORCPT ); Tue, 26 Jan 2016 20:02:09 -0500 Received: from mx1.redhat.com ([209.132.183.28]:41514 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750826AbcA0BCG (ORCPT ); Tue, 26 Jan 2016 20:02:06 -0500 Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 Subject: [PATCH] KEYS: Only apply KEY_FLAG_KEEP to a key if a parent keyring has it set From: David Howells To: jmorris@namei.org Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org, dhowells@redhat.com, linux-security-module@vger.kernel.org, keyrings@vger.kernel.org, sgallagh@redhat.com, Mimi Zohar Date: Wed, 27 Jan 2016 01:02:03 +0000 Message-ID: <20160127010203.27333.90518.stgit@warthog.procyon.org.uk> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org KEY_FLAG_KEEP should only be applied to a key if the keyring it is being linked into has KEY_FLAG_KEEP set. To this end, partially revert the following patch: commit 1d6d167c2efcfe9539d9cffb1a1be9c92e39c2c0 Author: Mimi Zohar Date: Thu Jan 7 07:46:36 2016 -0500 KEYS: refcount bug fix to undo the change that made it unconditional (Mimi got it right the first time). Without undoing this change, it becomes impossible to delete, revoke or invalidate keys added to keyrings through __key_instantiate_and_link() where the keyring has itself been linked to. To test this, run the following command sequence: keyctl newring foo @s keyctl add user a a %:foo keyctl unlink %user:a %:foo keyctl clear %:foo With the commit mentioned above the third and fourth commands fail with EPERM when they should succeed. Reported-by: Stephen Gallager Signed-off-by: David Howells cc: Mimi Zohar cc: keyrings@vger.kernel.org cc: stable@vger.kernel.org --- security/keys/key.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/security/keys/key.c b/security/keys/key.c index 07a87311055c..09ef276c4bdc 100644 --- a/security/keys/key.c +++ b/security/keys/key.c @@ -430,7 +430,8 @@ static int __key_instantiate_and_link(struct key *key, /* and link it into the destination keyring */ if (keyring) { - set_bit(KEY_FLAG_KEEP, &key->flags); + if (test_bit(KEY_FLAG_KEEP, &keyring->flags)) + set_bit(KEY_FLAG_KEEP, &key->flags); __key_link(key, _edit); }