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SubjectRe: [PATCH ghak90 V8 13/16] audit: track container nesting
On 2020-01-31 09:50, Steve Grubb wrote:
> On Wednesday, January 22, 2020 4:29:12 PM EST Paul Moore wrote:
> > On Tue, Dec 31, 2019 at 2:51 PM Richard Guy Briggs <rgb@redhat.com> wrote:
> > > Track the parent container of a container to be able to filter and
> > > report nesting.
> > >
> > > Now that we have a way to track and check the parent container of a
> > > container, modify the contid field format to be able to report that
> > > nesting using a carrat ("^") separator to indicate nesting. The
> > > original field format was "contid=<contid>" for task-associated records
> > > and "contid=<contid>[,<contid>[...]]" for network-namespace-associated
> > > records. The new field format is
> > > "contid=<contid>[^<contid>[...]][,<contid>[...]]".
> >
> > Let's make sure we always use a comma as a separator, even when
> > recording the parent information, for example:
> > "contid=<contid>[,^<contid>[...]][,<contid>[...]]"
> >
> > > Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
> > > ---
> > >
> > > include/linux/audit.h | 1 +
> > > kernel/audit.c | 53
> > > +++++++++++++++++++++++++++++++++++++++++++-------- kernel/audit.h
> > > | 1 +
> > > kernel/auditfilter.c | 17 ++++++++++++++++-
> > > kernel/auditsc.c | 2 +-
> > > 5 files changed, 64 insertions(+), 10 deletions(-)
> >
> > ...
> >
> > > diff --git a/kernel/audit.c b/kernel/audit.c
> > > index ef8e07524c46..68be59d1a89b 100644
> > > --- a/kernel/audit.c
> > > +++ b/kernel/audit.c
> > >
> > > @@ -492,6 +493,7 @@ void audit_switch_task_namespaces(struct nsproxy *ns,
> > > struct task_struct *p)>
> > > audit_netns_contid_add(new->net_ns, contid);
> > >
> > > }
> > >
> > > +void audit_log_contid(struct audit_buffer *ab, u64 contid);
> >
> > If we need a forward declaration, might as well just move it up near
> > the top of the file with the rest of the declarations.
> >
> > > +void audit_log_contid(struct audit_buffer *ab, u64 contid)
> > > +{
> > > + struct audit_contobj *cont = NULL, *prcont = NULL;
> > > + int h;
> >
> > It seems safer to pass the audit container ID object and not the u64.
> >
> > > + if (!audit_contid_valid(contid)) {
> > > + audit_log_format(ab, "%llu", contid);
> >
> > Do we really want to print (u64)-1 here? Since this is a known
> > invalid number, would "?" be a better choice?
>
> The established pattern is that we print -1 when its unset and "?" when its
> totalling missing. So, how could this be invalid? It should be set or not.
> That is unless its totally missing just like when we do not run with selinux
> enabled and a context just doesn't exist.

Ok, so in this case it is clearly unset, so should be -1, which will be a
20-digit number when represented as an unsigned long long int.

Thank you for that clarification Steve.

> -Steve
>
> > > + return;
> > > + }
> > > + h = audit_hash_contid(contid);
> > > + rcu_read_lock();
> > > + list_for_each_entry_rcu(cont, &audit_contid_hash[h], list)
> > > + if (cont->id == contid) {
> > > + prcont = cont;
> >
> > Why not just pull the code below into the body of this if statement?
> > It all needs to be done under the RCU read lock anyway and the code
> > would read much better this way.
> >
> > > + break;
> > > + }
> > > + if (!prcont) {
> > > + audit_log_format(ab, "%llu", contid);
> > > + goto out;
> > > + }
> > > + while (prcont) {
> > > + audit_log_format(ab, "%llu", prcont->id);
> > > + prcont = prcont->parent;
> > > + if (prcont)
> > > + audit_log_format(ab, "^");
> >
> > In the interest of limiting the number of calls to audit_log_format(),
> > how about something like the following:
> >
> > audit_log_format("%llu", cont);
> > iter = cont->parent;
> > while (iter) {
> > if (iter->parent)
> > audit_log_format("^%llu,", iter);
> > else
> > audit_log_format("^%llu", iter);
> > iter = iter->parent;
> > }
> >
> > > + }
> > > +out:
> > > + rcu_read_unlock();
> > > +}
> > > +
> > >
> > > /*
> > >
> > > * audit_log_container_id - report container info
> > > * @context: task or local context for record
> >
> > ...
> >
> > > @@ -2705,9 +2741,10 @@ int audit_set_contid(struct task_struct *task, u64
> > > contid)>
> > > if (!ab)
> > >
> > > return rc;
> > >
> > > - audit_log_format(ab,
> > > - "op=set opid=%d contid=%llu old-contid=%llu",
> > > - task_tgid_nr(task), contid, oldcontid);
> > > + audit_log_format(ab, "op=set opid=%d contid=",
> > > task_tgid_nr(task)); + audit_log_contid(ab, contid);
> > > + audit_log_format(ab, " old-contid=");
> > > + audit_log_contid(ab, oldcontid);
> >
> > This is an interesting case where contid and old-contid are going to
> > be largely the same, only the first (current) ID is going to be
> > different; do we want to duplicate all of those IDs?
> >
> > > audit_log_end(ab);
> > > return rc;
> > >
> > > }
> > >
> > > @@ -2723,9 +2760,9 @@ void audit_log_container_drop(void)
> >
> > 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

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