On Wed, 19 Aug 2015, Rick Stevens wrote:
> On 08/19/2015 08:41 AM, Robert P. J. Day wrote:
> > On Wed, 19 Aug 2015, Daniel J Walsh wrote:
> >
> >>
> >>
> >> On 08/19/2015 07:36 AM, Robert P. J. Day wrote:
> >>> On Wed, 19 Aug 2015, Daniel J Walsh wrote:
> >>>
> >>>> On 08/19/2015 02:43 AM, Robert P. J. Day wrote:
> >>>>> On Tue, 18 Aug 2015, Robert P. J. Day wrote:
> >>>>>
> >>>>>> by now, i'm getting *really* good at debugging. was doing a simple
> >>>>>> docker build (docker-1.8.1) with first few lines of Dockerfile (which
> >>>>>> worked fine not that long ago):
> >>>>>>
> >>>>>> FROM ubuntu:14.04
> >>>>>> MAINTAINER Robert P. J. Day
> >>>>>> ENV REFRESHED_AT 2015-08-18
> >>>>>>
> >>>>>> RUN apt-get -y -q update && apt-get -y -q install nginx
> >>>>>> ... snip ...
> >>>>>>
> >>>>>> and it was *entirely* reproducible that the instant docker started to
> >>>>>> process that "RUN apt-get" command, the wireless connection on my
> >>>>>> Fedora 22 laptop was blown away. grabbed this from SELinux:
> >>>>>>
> >>>>>> ===== start =====
> >>>>>>
> >>>>>> SELinux is preventing /usr/libexec/abrt-hook-ccpp from using the
> sigchld access on a process.
> >>>>>>
> >>>>>> ***** Plugin catchall (100. confidence) suggests
> **************************
> >>>>>>
> >>>>>> If you believe that abrt-hook-ccpp should be allowed sigchld access on
> processes labeled kernel_t by default.
> >>>>>> Then you should report this as a bug.
> >>>>>> You can generate a local policy module to allow this access.
> >>>>>> Do
> >>>>>> allow this access for now by executing:
> >>>>>> # grep abrt-hook-ccpp /var/log/audit/audit.log | audit2allow -M mypol
> >>>>>> # semodule -i mypol.pp
> >>>>>>
> >>>>>> Additional Information:
> >>>>>> Source Context system_u:system_r:NetworkManager_t:s0
> >>>>>> Target Context system_u:system_r:kernel_t:s0
> >>>>>> Target Objects Unknown [ process ]
> >>>>>> Source abrt-hook-ccpp
> >>>>>> Source Path /usr/libexec/abrt-hook-ccpp
> >>>>>> Port <Unknown>
> >>>>>> Host localhost.localdomain
> >>>>>> Source RPM Packages
> abrt-addon-coredump-helper-2.6.1-2.fc22.x86_64
> >>>>>> Target RPM Packages
> >>>>>> Policy RPM selinux-policy-3.13.1-128.10.fc22.noarch
> >>>>>> Selinux Enabled True
> >>>>>> Policy Type targeted
> >>>>>> Enforcing Mode Permissive
> >>>>>> Host Name localhost.localdomain
> >>>>>> Platform Linux localhost.localdomain
> 4.1.5-200.fc22.x86_64
> >>>>>> #1 SMP Mon Aug 10 23:38:23 UTC 2015
> x86_64 x86_64
> >>>>>> Alert Count 1
> >>>>>> First Seen 2015-08-18 12:57:36 EDT
> >>>>>> Last Seen 2015-08-18 12:57:36 EDT
> >>>>>> Local ID 523c8bed-7428-49e7-b301-3a932852b135
> >>>>>>
> >>>>>> Raw Audit Messages
> >>>>>> type=AVC msg=audit(1439917056.327:640): avc: denied { sigchld } for
> pid=4555 comm="abrt-hook-ccpp" scontext=system_u:system_r:NetworkManager_t:s0
> tcontext=system_u:system_r:kernel_t:s0 tclass=process permissive=1
> >>>>>>
> >>>>>>
> >>>>>> type=SYSCALL msg=audit(1439917056.327:640): arch=x86_64 syscall=wait4
> success=yes exit=1273 a0=4f9 a1=7fffdb95f19c a2=0 a3=0 items=0 ppid=131
> pid=4555 auid=4294967295 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0
> fsgid=0 tty=(none) ses=4294967295 comm=abrt-hook-ccpp
> exe=/usr/libexec/abrt-hook-ccpp subj=system_u:system_r:kernel_t:s0 key=(null)
> >>>>>>
> >>>>>> Hash: abrt-hook-ccpp,NetworkManager_t,kernel_t,process,sigchld
> >>>>>>
> >>>>>> ===== end =====
> >>>>> followup to the above ... i ran the suggested selinux-related
> >>>>> commands, but that had no apparent effect, so i'm still stuck. for
> >>>>> people who know docker, you'll recognize that the error occurred at
> >>>>> the first instruction in the Dockerfile that requires network access,
> >>>>> the "RUN apt-get ..." command (i already have the ubuntu base image on
> >>>>> my system).
> >>>>>
> >>>>> i grabbed a few hundred lines from "journalctl" and stuck them here:
> >>>>> http://pastebin.com/KzrYMFvC. you can see the very first command there
> >>>>> is the docker invocation:
> >>>>>
> >>>>> Aug 19 05:24:35 localhost.localdomain sudo[4190]: rpjday : TTY=pts/0
> >>>>> ; PWD=/home/rpjday/docker/TDB/sample ; USER=root ; COMMAND=/bin/docker
> >>>>> build -t jamtur01/nginx .
> >>>>>
> >>>>> thoughts? is it bugzilla time?
> >>>>>
> >>>>> rday
> >>>>>
> >>>> Yes open a bugzilla, although this is a very strange AVC. It basically
> >>>> shows abrt-hook-ccpp executing under networkmanager domain and sending
> >>>> sigchld to kernel_t.
> >>>>
> >>>> Why would networkmanager execed processes be sending a sigchld to a
> >>>> kernel process?
> >>> beats me, this is way outside my comfort zone. by the way, even
> >>> though selinux was in permissive mode, i thought i'd play it safe and
> >>> just disable it entirely, so i did, rebooted, "sestatus" clearly shows
> >>> selinux disabled, but i got the same error.
> >>>
> >>> i'll do it one more time shortly just to make sure it's not some
> >>> intermittent weirdness, then i'll BZ it. open to suggestions as to
> >>> anything else i might try, or add to the BZ submission.
> >>>
> >>> rday
> >>>
> >> With SELinux disabled you should not be getting any AVC's
> >>
> >> If you turn SELInux back on and do a full relabel, I think the
> >> problem will go away.
> >
> > no difference ... i edited /etc/selinux/config, set
> > SELINUX=enforcing, rebooted and let my system chug away relabelling,
> > came back up, tested again ... same result.
>
> While I have seen both AVCs and actual blocks from selinux in
> permissive mode in the past (and specifically on network stuff), if
> you've disabled selinux on the host machine I don't see how it could
> generate an AVC at all.
>
> Are you certain the AVC isn't coming from the dockerized OS itself? I
> could see the AVC being generated on the docker and getting reflected
> back to the host somehow (I suspect critical messages from the dockers
> get piped through so you're aware of them, but that's a wild guess).
i have no doubt that the container OS is the *ultimate* source of
the problem, but that in no way explains how it can reach out from the
container and blow away the wireless connection on the host. that's
what leaves me baffled.
rday
--
========================================================================
Robert P. J. Day Ottawa, Ontario, CANADA
http://crashcourse.ca
Twitter: http://twitter.com/rpjday
LinkedIn: http://ca.linkedin.com/in/rpjday
========================================================================
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