linux-kernel - Re: [PATCH 1/2] KEYS: Replace uid/gid/perm permissions checking with an ACL

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Date:   Tue, 30 Jul 2019 18:16:14 -0700
From:   Eric Biggers <ebiggers@...nel.org>
To:     David Howells <dhowells@...hat.com>, keyrings@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] KEYS: Replace uid/gid/perm permissions checking with
 an ACL

On Mon, Jul 29, 2019 at 08:49:56PM -0700, Eric Biggers wrote:
> Hi David,
> 
> On Tue, Jul 09, 2019 at 06:16:01PM -0700, Eric Biggers wrote:
> > On Thu, May 23, 2019 at 04:58:27PM +0100, David Howells wrote:
> > > Replace the uid/gid/perm permissions checking on a key with an ACL to allow
> > > the SETATTR and SEARCH permissions to be split.  This will also allow a
> > > greater range of subjects to represented.
> > > 
> > 
> > This patch broke 'keyctl new_session', and hence broke all the fscrypt tests:
> > 
> > $ keyctl new_session
> > keyctl_session_to_parent: Permission denied
> > 
> > Output of 'keyctl show' is
> > 
> > $ keyctl show
> > Session Keyring
> >  605894913 --alswrv      0     0  keyring: _ses
> >  189223103 ----s-rv      0     0   \_ user: invocation_id
> > 
> > - Eric
> 
> This bug is still present in next-20190729.
> 
> - Eric

This fixes it:

diff --git a/security/keys/process_keys.c b/security/keys/process_keys.c
index aa3bfcadbc660..519c94f1cc3c2 100644
--- a/security/keys/process_keys.c
+++ b/security/keys/process_keys.c
@@ -58,7 +58,7 @@ static struct key_acl session_keyring_acl = {
 	.possessor_viewable = true,
 	.nr_ace	= 2,
 	.aces = {
-		KEY_POSSESSOR_ACE(KEY_ACE__PERMS & ~KEY_ACE_JOIN),
+		KEY_POSSESSOR_ACE(KEY_ACE__PERMS),
 		KEY_OWNER_ACE(KEY_ACE_VIEW | KEY_ACE_READ),
 	}
 };


The old permissions were KEY_POS_ALL | KEY_USR_VIEW | KEY_USR_READ, so
I'm not sure why JOIN permission was removed?

- Eric