Re: [RFC PATCH] security,anon_inodes,kvm: enable security support for anon inodes

From: Stephen Smalley <stephen.smalley.work@gmail.com>
To: Daniel Colascione <dancol@google.com>
Cc: Casey Schaufler <casey@schaufler-ca.com>,
	Sandeep Patil <sspatil@google.com>,
	Paul Moore <paul@paul-moore.com>,
	LSM List <linux-security-module@vger.kernel.org>,
	Linux FS Devel <linux-fsdevel@vger.kernel.org>,
	Al Viro <viro@zeniv.linux.org.uk>,
	SElinux list <selinux@vger.kernel.org>,
	kvm@vger.kernel.org, Nick Kralevich <nnk@google.com>,
	Stephen Smalley <sds@tycho.nsa.gov>
Subject: Re: [RFC PATCH] security,anon_inodes,kvm: enable security support for anon inodes
Date: Wed, 11 Mar 2020 09:31:34 -0400
Message-ID: <CAEjxPJ7DykRX7Q1NLhtRh123rjAvW4t6symJ5ochth+iCyg3kg@mail.gmail.com> (raw)
In-Reply-To: <CAKOZuevcz+fvfhRXPx2iZGtkk6+FjVj3ZSaGGT8DfwsOJR0k3A@mail.gmail.com>

On Tue, Mar 10, 2020 at 5:51 PM Daniel Colascione <dancol@google.com> wrote:
>
> On Tue, Mar 10, 2020 at 11:25 AM Stephen Smalley
> <stephen.smalley.work@gmail.com> wrote:
> >
> > On Tue, Mar 10, 2020 at 2:11 PM Daniel Colascione <dancol@google.com> wrote:
> > >
> > > On Thu, Feb 20, 2020 at 10:50 AM Daniel Colascione <dancol@google.com> wrote:
> > > >
> > > > On Thu, Feb 20, 2020 at 10:11 AM Casey Schaufler <casey@schaufler-ca.com> wrote:
> > > > >
> > > > > On 2/17/2020 4:14 PM, Paul Moore wrote:
> > > > > > On Thu, Feb 13, 2020 at 2:41 PM Stephen Smalley <sds@tycho.nsa.gov> wrote:
> > > > > >> We are primarily posting this RFC patch now so that the two different
> > > > > >> approaches can be concretely compared.  We anticipate a hybrid of the
> > > > > >> two approaches being the likely outcome in the end.  In particular
> > > > > >> if support for allocating a separate inode for each of these files
> > > > > >> is acceptable, then we would favor storing the security information
> > > > > >> in the inode security blob and using it instead of the file security
> > > > > >> blob.
> > > > > > Bringing this back up in hopes of attracting some attention from the
> > > > > > fs-devel crowd and Al.  As Stephen already mentioned, from a SELinux
> > > > > > perspective we would prefer to attach the security blob to the inode
> > > > > > as opposed to the file struct; does anyone have any objections to
> > > > > > that?
> > > > >
> > > > > Sorry for the delay - been sick the past few days.
> > > > >
> > > > > I agree that the inode is a better place than the file for information
> > > > > about the inode. This is especially true for Smack, which uses
> > > > > multiple extended attributes in some cases. I don't believe that any
> > > > > except the access label will be relevant to anonymous inodes, but
> > > > > I can imagine security modules with policies that would.
> > > > >
> > > > > I am always an advocate of full xattr support. It goes a long
> > > > > way in reducing the number and complexity of special case interfaces.
> > > >
> > > > It sounds like we have broad consensus on using the inode to hold
> > > > security information, implying that anon_inodes should create new
> > > > inodes. Do any of the VFS people want to object?
> > >
> > > Ping?
> >
> > I'd recommend refreshing your patch series to incorporate feedback on
> > the previous version and re-post,
> > including viro and linux-fsdevel on the cc, and see if they have any
> > comments on it.
>
> I don't think there's anything in the patch series that needs to
> change right now. AFAICT, we're still just waiting on comment from the
> VFS people, who should be on this thread. Did I miss something?

There was some discussion on the SELinux bits in patch 2/3.  I would
take the silence on
the vfs bits as implicit acceptance until you hear otherwise and just
submit a v2 that addresses
the SELinux bits.