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

[Paul Moore <paul@paul-moore.com>]

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.

-- 
paul moore
www.paul-moore.com