lkml.org 
[lkml]   [2019]   [Oct]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH ghak90 V7 06/21] audit: contid limit of 32k imposed to avoid DoS
On Fri, Sep 27, 2019 at 8:52 AM Neil Horman <nhorman@tuxdriver.com> wrote:
> On Wed, Sep 18, 2019 at 09:22:23PM -0400, Richard Guy Briggs wrote:
> > Set an arbitrary limit on the number of audit container identifiers to
> > limit abuse.
> >
> > Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
> > ---
> > kernel/audit.c | 8 ++++++++
> > kernel/audit.h | 4 ++++
> > 2 files changed, 12 insertions(+)
> >
> > diff --git a/kernel/audit.c b/kernel/audit.c
> > index 53d13d638c63..329916534dd2 100644
> > --- a/kernel/audit.c
> > +++ b/kernel/audit.c

...

> > @@ -2465,6 +2472,7 @@ int audit_set_contid(struct task_struct *task, u64 contid)
> > newcont->owner = current;
> > refcount_set(&newcont->refcount, 1);
> > list_add_rcu(&newcont->list, &audit_contid_hash[h]);
> > + audit_contid_count++;
> > } else {
> > rc = -ENOMEM;
> > goto conterror;
> > diff --git a/kernel/audit.h b/kernel/audit.h
> > index 162de8366b32..543f1334ba47 100644
> > --- a/kernel/audit.h
> > +++ b/kernel/audit.h
> > @@ -219,6 +219,10 @@ static inline int audit_hash_contid(u64 contid)
> > return (contid & (AUDIT_CONTID_BUCKETS-1));
> > }
> >
> > +extern int audit_contid_count;
> > +
> > +#define AUDIT_CONTID_COUNT 1 << 16
> > +
>
> Just to ask the question, since it wasn't clear in the changelog, what
> abuse are you avoiding here? Ostensibly you should be able to create as
> many container ids as you have space for, and the simple creation of
> container ids doesn't seem like the resource strain I would be concerned
> about here, given that an orchestrator can still create as many
> containers as the system will otherwise allow, which will consume
> significantly more ram/disk/etc.

I've got a similar question. Up to this point in the patchset, there
is a potential issue of hash bucket chain lengths and traversing them
with a spinlock held, but it seems like we shouldn't be putting an
arbitrary limit on audit container IDs unless we have a good reason
for it. If for some reason we do want to enforce a limit, it should
probably be a tunable value like a sysctl, or similar.

--
paul moore
www.paul-moore.com

\
 
 \ /
  Last update: 2019-10-11 02:40    [W:0.082 / U:0.188 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site