Return-Path: linux-nfs-owner@vger.kernel.org Received: from mx1.redhat.com ([209.132.183.28]:58131 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752763AbaCLKWN (ORCPT ); Wed, 12 Mar 2014 06:22:13 -0400 Date: Wed, 12 Mar 2014 06:22:07 -0400 From: Jeff Layton To: Trond Myklebust Cc: Eric Paris , Schumaker Anna , David Quigley , Linux NFS Mailing List , James Morris Subject: Re: [PATCH] nfs: Don't assume we have a security structure Message-ID: <20140312062207.6b2ee85e@tlielax.poochiereds.net> In-Reply-To: References: <1394572274-16474-1-git-send-email-Anna.Schumaker@netapp.com> <29D9CA49-A493-471B-932B-959AFF96C729@primarydata.com> <1394584698.10287.0.camel@localhost> <20140311210611.0e82e3cf@ipyr.poochiereds.net> MIME-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Sender: linux-nfs-owner@vger.kernel.org List-ID: On Wed, 12 Mar 2014 05:21:13 -0400 Trond Myklebust wrote: > > On Mar 11, 2014, at 21:06, Jeffrey Layton wrote: > > > On Tue, 11 Mar 2014 20:38:18 -0400 > > Eric Paris wrote: > > > >> On Tue, 2014-03-11 at 18:00 -0400, Trond Myklebust wrote: > >>> On Mar 11, 2014, at 17:27, Trond Myklebust > >>> wrote: > >>> > >>>> > >>>> On Mar 11, 2014, at 17:11, Anna Schumaker > >>>> wrote: > >>>> > >>>>> If the i_security field isn't set then > >>>>> security_dentry_init_security() won't initialize some of the > >>>>> values used by the security label. This causes my client to hit > >>>>> a BUG_ON() while encoding a label of size -2128927414. > >>>>> > >>>>> I hit this bug while testing on a client without SELinux > >>>>> installed. > >>>>> > >>>>> Signed-off-by: Anna Schumaker > >>>>> --- > >>>>> fs/nfs/nfs4proc.c | 3 +++ > >>>>> 1 file changed, 3 insertions(+) > >>>>> > >>>>> diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c > >>>>> index b8cd560..994ccc2 100644 > >>>>> --- a/fs/nfs/nfs4proc.c > >>>>> +++ b/fs/nfs/nfs4proc.c > >>>>> @@ -105,6 +105,9 @@ nfs4_label_init_security(struct inode *dir, > >>>>> struct dentry *dentry, if (nfs_server_capable(dir, > >>>>> NFS_CAP_SECURITY_LABEL) == 0) return NULL; > >>>>> > >>>>> + if (!dir->i_security) > >>>>> + return NULL; > >>>>> + > >>>>> err = security_dentry_init_security(dentry, > >>>>> sattr->ia_mode, &dentry->d_name, (void **)&label->label, > >>>>> &label->len); if (err == 0) > >>>> > >>>> Hi Anna, > >>>> > >>>> This looks like a check that needs to be done by > >>>> selinux_dentry_init_security() itself. The dir->i_security field > >>>> is not something that NFS knows about. David, what needs to > >>>> happen there when dentry->d_parent->i_security (a.k.a. dsec) is > >>>> NULL? > >>>> > >>> > >>> Oh, wait. I missed the bit about ?without SELinux installed?. So > >>> the problem here is that you have a NFS client that does not have > >>> SELinux set up, but running against a server that is advertising > >>> NFSv4.2 with labeled NFS. Is that correct? > >>> > >>> It looks to me as if cap_dentry_init_security() will indeed trigger > >>> this behaviour since it returns ?0? without doing anything to the > >>> label. As far as I can see, the right thing to do there is to > >>> return -EOPNOTSUPP, no? > >> > >> I feel like Jeff Layton was looking at the same thing, and came to the > >> same conclusion... > >> > >> Jeff? > >> > > > > I posted a patch for this last week and James has merged it: > > > > [PATCH] security: have cap_dentry_init_security return error > > > > I didn't note it in the patch description but it fixes 4.2 when SELinux > > is compiled in but disabled. > > Thanks! Then I expect no further action is needed on our part, and that the fix will come through the security tree? > FWIW, this is the bug that was causing the NFS server to spew messages like this to the ring buffer when Anna was testing against my server at Connectathon: [ 243.479524] SELinux: Context \xffffffdf is not valid (left unmapped). We may want to do a follow-on patch to clean up the struct nfs4_label initializers since they're not really needed. But that should probably wait until James merges this up to Linus. -- Jeff Layton