From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-12.0 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 251CFC43381 for ; Thu, 28 Mar 2019 15:46:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EB04121773 for ; Thu, 28 Mar 2019 15:46:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=paul-moore-com.20150623.gappssmtp.com header.i=@paul-moore-com.20150623.gappssmtp.com header.b="IXm0uTio" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726543AbfC1Pqi (ORCPT ); Thu, 28 Mar 2019 11:46:38 -0400 Received: from mail-lf1-f65.google.com ([209.85.167.65]:40866 "EHLO mail-lf1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727248AbfC1Pqc (ORCPT ); Thu, 28 Mar 2019 11:46:32 -0400 Received: by mail-lf1-f65.google.com with SMTP id a28so1580205lfo.7 for ; Thu, 28 Mar 2019 08:46:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=paul-moore-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=J1rFfeVPNUL+mQFkDcYvOnRRpb0BJX1LnqaH9dlaLrA=; b=IXm0uTioHR+okF+fTsHaYrYYAekPBiBJMebQE4H7r1z1k5dw+25gNWdvrlgw8xWECT ukz7+d49nkLkiKYy91EhGK0XChliJF8I7WM80SM1ozdhrHg2EqzMfmb9WRHIb2ORyegh JUYealFUD5PD5TUpL/sJEYJl96SgWUShs7ARIL+M5UVshzTyPsyOoCvlnjSrN6WKRp0w H1FWRSpKveXpmv9abc0MHBQsvK2dIhMUZCcW8F5GKuo2U/bwo9jzwQQspVkRvukK0I3k jEEhcXTmTpNEEiqYzEmrMp4nrCS60AKGRZ4631QYF6OfxyuyJWpRFIDBxakb5oML78t0 aUJA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=J1rFfeVPNUL+mQFkDcYvOnRRpb0BJX1LnqaH9dlaLrA=; b=F9ip9ItJnj+9FK8P0+89XDcqt5ooyApKq8vYm4oOGulPo6SfPuVlKPx7JBBYsx6yPk M06f2fl7kSR2shQNbfo0uyDLRuBCh8Lr3vz24gPDSoBx7x4dAjovQM2dqWkbTuI1YHLr x2EyKFKf7o0JZe+RyC8VBOPD38K1K6uRJIYtLfv0RILsa2CNj+ZKrDNpmL01v69Z0eTY FlEX/KBnBYGYrx0179wWlT0dgn+R57iy6XjwuVUO6Y+bEFXP25emQLY2GwCvtkSRC5Nr 72VSQJvmrbqNa87KNKU2yqW4hYjshPGAPJJpacr50FA/V3AUCUslBWtFXRG4GOjlMmYF +NtA== X-Gm-Message-State: APjAAAUz9vEjvf6HnqV/UZxDkoDAw9wGmKWdq7wmnkUdLYtbkQ+3Nxlw aItm9QAPIr87yhqtThwpuGTdyTkesLNsIQ6ZGwYf X-Google-Smtp-Source: APXvYqwfamkxPb14Cc1V2TuMg4flLBeLIGPcDXA/dCCnkaDofWxUeAigJP0pgRGG5dXe3x8C2hdvRTi9ESq6CBnrvP0= X-Received: by 2002:a19:ee11:: with SMTP id g17mr21733682lfb.117.1553787989146; Thu, 28 Mar 2019 08:46:29 -0700 (PDT) MIME-Version: 1.0 References: <27473c84a274c64871cfa8e3636deaf05603c978.1552665316.git.rgb@redhat.com> <20190328011202.6raixwzdimn5b4zk@madcap2.tricolour.ca> In-Reply-To: <20190328011202.6raixwzdimn5b4zk@madcap2.tricolour.ca> From: Paul Moore Date: Thu, 28 Mar 2019 11:46:17 -0400 Message-ID: Subject: Re: [PATCH ghak90 V5 09/10] audit: add support for containerid to network namespaces To: Richard Guy Briggs Cc: Ondrej Mosnacek , nhorman@tuxdriver.com, linux-api@vger.kernel.org, containers@lists.linux-foundation.org, LKML , David Howells , Linux-Audit Mailing List , netfilter-devel@vger.kernel.org, "Eric W . Biederman" , Simo Sorce , netdev@vger.kernel.org, linux-fsdevel@vger.kernel.org, Eric Paris , "Serge E. Hallyn" Content-Type: text/plain; charset="UTF-8" Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Wed, Mar 27, 2019 at 9:12 PM Richard Guy Briggs wrote: > > On 2019-03-27 23:42, Ondrej Mosnacek wrote: > > On Fri, Mar 15, 2019 at 7:35 PM Richard Guy Briggs 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 be 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 audit container identifiiers. > > > > > > Add/increment the audit container identifier on: > > > - initial setting of the audit container identifier via /proc > > > - clone/fork call that inherits an audit container identifier > > > - unshare call that inherits an audit container identifier > > > - setns call that inherits an audit container identifier > > > Delete/decrement the audit container identifier on: > > > - an inherited audit container identifier 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/92 > > > See: https://github.com/linux-audit/audit-testsuite/issues/64 > > > See: https://github.com/linux-audit/audit-kernel/wiki/RFE-Audit-Container-ID > > > Signed-off-by: Richard Guy Briggs > > > --- > > > include/linux/audit.h | 19 ++++++++++++ > > > kernel/audit.c | 86 +++++++++++++++++++++++++++++++++++++++++++++++++-- > > > kernel/nsproxy.c | 4 +++ > > > 3 files changed, 106 insertions(+), 3 deletions(-) > > > > > > diff --git a/include/linux/audit.h b/include/linux/audit.h > > > index fa19fa408931..70255c2dfb9f 100644 > > > --- a/include/linux/audit.h > > > +++ b/include/linux/audit.h > > > @@ -27,6 +27,7 @@ > > > #include > > > #include /* LOOKUP_* */ > > > #include > > > +#include > > > > > > #define AUDIT_INO_UNSET ((unsigned long)-1) > > > #define AUDIT_DEV_UNSET ((dev_t)-1) > > > @@ -99,6 +100,13 @@ struct audit_task_info { > > > > > > extern struct audit_task_info init_struct_audit; > > > > > > +struct audit_contid { > > > + struct list_head list; > > > + u64 id; > > > + refcount_t refcount; > > > > Hm, since we only ever touch the refcount under a spinlock, I wonder > > if we could just make it a regular unsigned int (we don't need the > > atomicity guarantees). OTOH, refcount_t comes with some extra overflow > > checking, so it's probably better to leave it as is... > > Since the update is done using rcu-safe methods, do we even need the > spin_lock? Neil? Paul? As discussed, the refcount field is protected against simultaneous writes by the spinlock that protects additions/removals from the list as a whole so I don't believe the refcount_t atomicity is critical in this regard. Where it gets tricky, and I can't say I'm 100% confident on my answer here, is if refcount was a regular int and we wanted to access it outside of a spinlock (to be clear, it doesn't look like this patch currently does this). With RCU, if refcount was a regular int (unsigned or otherwise), I believe it would be possible for different threads of execution to potentially see different values of refcount (assuming one thread was adding/removing from the list). Using a refcount_t would protect against this, alternatively, taking the spinlock should also protect against this. As we all know, RCU can be tricky at times, so I may be off on the above; if I am, please provide an explanation so I (and likely others as well) can learn a little bit more. :) -- paul moore www.paul-moore.com