linux-kernel - Re: [PATCH ghak25 v2 0/9] Address NETFILTER

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Date:   Thu, 16 Jan 2020 16:20:23 -0500
From:   Richard Guy Briggs <rgb@...hat.com>
To:     Paul Moore <paul@...l-moore.com>
Cc:     Pablo Neira Ayuso <pablo@...filter.org>,
        Linux-Audit Mailing List <linux-audit@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>,
        netfilter-devel@...r.kernel.org, sgrubb@...hat.com,
        omosnace@...hat.com, fw@...len.de, twoerner@...hat.com,
        Eric Paris <eparis@...isplace.org>, ebiederm@...ssion.com,
        tgraf@...radead.org
Subject: Re: [PATCH ghak25 v2 0/9] Address NETFILTER_CFG issues

On 2020-01-16 14:07, Paul Moore wrote:
> On Thu, Jan 16, 2020 at 10:05 AM Pablo Neira Ayuso <pablo@...filter.org> wrote:
> > On Mon, Jan 06, 2020 at 01:54:01PM -0500, Richard Guy Briggs wrote:
> > > There were questions about the presence and cause of unsolicited syscall events
> > > in the logs containing NETFILTER_CFG records and sometimes unaccompanied
> > > NETFILTER_CFG records.
> > >
> > > During testing at least the following list of events trigger NETFILTER_CFG
> > > records and the syscalls related (There may be more events that will trigger
> > > this message type.):
> > >       init_module, finit_module: modprobe
> > >       setsockopt: iptables-restore, ip6tables-restore, ebtables-restore
> > >       unshare: (h?)ostnamed
> > >       clone: libvirtd
> > >
> > > The syscall events unsolicited by any audit rule were found to be caused by a
> > > missing !audit_dummy_context() check before creating a NETFILTER_CFG
> > > record and issuing the record immediately rather than saving the
> > > information to create the record at syscall exit.
> > > Check !audit_dummy_context() before creating the NETFILTER_CFG record.
> > >
> > > The vast majority of unaccompanied records are caused by the fedora default
> > > rule: "-a never,task" and the occasional early startup one is I believe caused
> > > by the iptables filter table module hard linked into the kernel rather than a
> > > loadable module. The !audit_dummy_context() check above should avoid them.
> > >
> > > A couple of other factors should help eliminate unaccompanied records
> > > which include commit cb74ed278f80 ("audit: always enable syscall
> > > auditing when supported and audit is enabled") which makes sure that
> > > when audit is enabled, so automatically is syscall auditing, and ghak66
> > > which addressed initializing audit before PID 1.
> > >
> > > Ebtables module initialization to register tables doesn't generate records
> > > because it was never hooked in to audit.  Recommend adding audit hooks to log
> > > this.
> > >
> > > Table unregistration was never logged, which is now covered.
> > >
> > > Seemingly duplicate records are not actually exact duplicates that are caused
> > > by netfilter table initialization in different network namespaces from the same
> > > syscall.  Recommend adding the network namespace ID (proc inode and dev)
> > > to the record to make this obvious (address later with ghak79 after nsid
> > > patches).
> > >
> > > See: https://github.com/linux-audit/audit-kernel/issues/25
> > > See: https://github.com/linux-audit/audit-kernel/issues/35
> > > See: https://github.com/linux-audit/audit-kernel/issues/43
> > > See: https://github.com/linux-audit/audit-kernel/issues/44
> >
> > What tree is this batch targeted to?
> 
> I believe Richard was targeting this for the audit tree.

Yes, sorry Pablo, it is against audit/next based on v5.5-rc1

> paul moore

- RGB

--
Richard Guy Briggs <rgb@...hat.com>
Sr. S/W Engineer, Kernel Security, Base Operating Systems
Remote, Ottawa, Red Hat Canada
IRC: rgb, SunRaycer
Voice: +1.647.777.2635, Internal: (81) 32635