Re: [RFC PATCH ghak32 V2 11/13] audit: add support for containerid to network namespaces

[Richard Guy Briggs <rgb@redhat.com>]

On 2018-04-20 16:22, Paul Moore wrote:
> On Fri, Apr 20, 2018 at 4:02 PM, Richard Guy Briggs <rgb@redhat.com> wrote:
> > On 2018-04-18 21:46, Paul Moore wrote:
> >> On Fri, Mar 16, 2018 at 5:00 AM, Richard Guy Briggs <rgb@redhat.com> wrote:
> >> > Audit events could happen in a network namespace outside of a task
> >> > context due to packets received from the net that trigger an auditing
> >> > rule prior to being associated with a running task.  The network
> >> > namespace could in use by multiple containers by association to the
> >> > tasks in that network namespace.  We still want a way to attribute
> >> > these events to any potential containers.  Keep a list per network
> >> > namespace to track these container identifiiers.
> >> >
> >> > Add/increment the container identifier on:
> >> > - initial setting of the container id via /proc
> >> > - clone/fork call that inherits a container identifier
> >> > - unshare call that inherits a container identifier
> >> > - setns call that inherits a container identifier
> >> > Delete/decrement the container identifier on:
> >> > - an inherited container id dropped when child set
> >> > - process exit
> >> > - unshare call that drops a net namespace
> >> > - setns call that drops a net namespace
> >> >
> >> > See: https://github.com/linux-audit/audit-kernel/issues/32
> >> > See: https://github.com/linux-audit/audit-testsuite/issues/64
> >> > Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
> >> > ---
> >> >  include/linux/audit.h       |  7 +++++++
> >> >  include/net/net_namespace.h | 12 ++++++++++++
> >> >  kernel/auditsc.c            |  9 ++++++---
> >> >  kernel/nsproxy.c            |  6 ++++++
> >> >  net/core/net_namespace.c    | 45 +++++++++++++++++++++++++++++++++++++++++++++
> >> >  5 files changed, 76 insertions(+), 3 deletions(-)
> 
> ...
> 
> >> > diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
> >> > index f6c5d33..d9f1090 100644
> >> > --- a/kernel/nsproxy.c
> >> > +++ b/kernel/nsproxy.c
> >> > @@ -140,6 +140,7 @@ int copy_namespaces(unsigned long flags, struct task_struct *tsk)
> >> >         struct nsproxy *old_ns = tsk->nsproxy;
> >> >         struct user_namespace *user_ns = task_cred_xxx(tsk, user_ns);
> >> >         struct nsproxy *new_ns;
> >> > +       u64 containerid = audit_get_containerid(tsk);
> >> >
> >> >         if (likely(!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
> >> >                               CLONE_NEWPID | CLONE_NEWNET |
> >> > @@ -167,6 +168,7 @@ int copy_namespaces(unsigned long flags, struct task_struct *tsk)
> >> >                 return  PTR_ERR(new_ns);
> >> >
> >> >         tsk->nsproxy = new_ns;
> >> > +       net_add_audit_containerid(new_ns->net_ns, containerid);
> >> >         return 0;
> >> >  }
> >>
> >> Hopefully we can handle this in audit_net_init(), we just need to
> >> figure out where we can get the correct task_struct for the audit
> >> container ID (some backpointer in the net struct?).
> >
> > I don't follow.  This needs to happen on every task startup.
> > audit_net_init() is only called when a new network namespace starts up.
> 
> Yep, sorry, my mistake.  I must have confused myself when I was
> looking at the code.
> 
> I'm thinking out loud here, bear with me ...
> 
> Assuming we move the netns/audit-container-ID tracking to audit_net,
> and considering we already have an audit hook in copy_process() (it
> calls audit_alloc()), would this be better handled by the
> copy_process() hook?  This ignores naming, audit_alloc() reuse, etc.;
> those can be easily fixed.  I'm just thinking of ways to limit our
> impact on the core kernel and leverage our existing interaction
> points.

The new namespace hasn't been cloned yet and this is the only function
where we have access to both namespaces, so I don't see how that could
work...

> paul moore

- RGB

--
Richard Guy Briggs <rgb@redhat.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