Debian buster LXC container

aalmenar

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Jan 12, 2014
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Hi everyone,

Just dropping a question i cant find around the forum.

I managed to create an image using dab but since some days ago, im unable to install/start any service on the container. Im constantly getting apparmor errors like this one when installing mariadb:

[510907.402767] audit: type=1400 audit(1546941509.083:189): apparmor="DENIED" operation="mount" info="failed flags match" error=-13 profile="lxc-9002_</var/lib/lxc>" name="/" pid=30859 comm="(install)" flags="rw, rslave"

Also with a clean container, trying to install apache2 also becomes practically impossible:

[511748.194258] audit: type=1400 audit(1546942349.893:190): apparmor="DENIED" operation="mount" info="failed flags match" error=-13 profile="lxc-9002_</var/lib/lxc>" name="/" pid=1698 comm="(pachectl)" flags="rw, rslave"

They were working nicely until 3 days ago.

Another service is dovecot with the same error:

[519311.829786] audit: type=1400 audit(1546949913.651:193): apparmor="DENIED" operation="mount" info="failed flags match" error=-13 profile="lxc-9002_</var/lib/lxc>" name="/" pid=24770 comm="(dovecot)" flags="rw, rslave"

The reason its to test software with the next debian version running on containers.

Any help will be appreciated.

Regards.
 
Last edited:

oguz

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Nov 19, 2018
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Can you post your container config? /etc/pve/lxc/CTID.conf
 

aalmenar

Member
Jan 12, 2014
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Hi oguz,

Yes:
Code:
arch: amd64
cores: 2
hostname: host10.mydomain.com
memory: 2048
net0: name=eth0,bridge=vmbr0,gw=192.0.2.1,gw6=2001:db8::,hwaddr=0A:C6:94:AB:B3:7A,ip=192.0.2.10/24,ip6=2001:db8:ffff::3/56,tag=10,type=veth
ostype: debian
rootfs: local-lvm:vm-9002-disk-0,quota=1,size=30G
swap: 0

Can you post your container config? /etc/pve/lxc/CTID.conf
 
Last edited:

oguz

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Nov 19, 2018
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I think we will need more information about your template to have a better idea of the problem.

Maybe it would be helpful to see the template's dab config file.

They where working nicely until 3 days ago.

Have you updated anything before this started happening? If yes, which packages?
 

aalmenar

Member
Jan 12, 2014
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The Template is like this:

Makefile:
Code:
BASEDIR:=$(shell dab basedir)

.DEFAULT_GOAL := all

.PHONY: all
all: info/init_ok global finalize

finalize:
    echo "10.0 " > ${BASEDIR}/etc/debian_version
    dab finalize

info/init_ok: dab.conf
    dab init
    touch $@
    dab bootstrap --minimal

.PHONY: clean
clean:
    dab clean
    rm -f *~

.PHONY: dist-clean
dist-clean:
    dab dist-clean
    rm -f *~

dab.conf:
Code:
Suite: buster
CacheDir: ../cache
Source: [URL]http://http.debian.net/debian[/URL] SUITE main contrib
Source: [URL]http://http.debian.net/debian[/URL] SUITE-updates main contrib
Source: [URL]http://http.debian.net/debian-security[/URL] SUITE/updates main contrib
Architecture: amd64
Name: debian-10.0-minimal
Version: 20190108-1
Section: system
Maintainer: Someone <someone@mydomain.com>
Infopage: [URL]http://mydomain.com[/URL]
Description: Debian 10 (minimal)
 A small Debian Buster system.


I think we will need more information about your template to have a better idea of the problem.

Maybe it would be helpful to see the template's dab config file.



Have you updated anything before this started happening? If yes, which packages?

Since it's kind of moving target, lots of packages, but installing a template made today and trying to exec anything of those packages give the same error. (I believe it's due to systemd update) since apache2 can start if on systemd unit i change PrivateTmp=true to false, but in mariadb this value is set to false and doesn't start.
 
Last edited:

fabian

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Jan 7, 2016
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might be related to the systemd v240 migration to testing on januaray 1st?
 

t.lamprecht

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might be related to the systemd v240 migration to testing on januaray 1st?

Yes, systemd 240 enforces now a few things which were earlier not, the PrivateTmp option from the apache2 unit file failed also in stretch (would need a "lxc.apparmor.raw: mount options=(rw,make-rslave) -> **," config option, which is potentialy dangerous as it allows a lot more), but while in stretch systemd just continued, in buster it just fails. Also some other default things like rbind mounting root to "/run/systemd/unit-root/" fails and is not easily possible to allow through apparmor in a sane unproblematic way...
 
Last edited:

aalmenar

Member
Jan 12, 2014
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Yes. Earlier I though of systemd update as the main issue on this, but maybe there is a workaround, or just it is not possible?

My apparmor knowledge is scarce to say the least.

Yes, systemd 240 enforces now a few things which were earlier not, the PrivateTmp option from the apache2 unit file failed also in stretch (would need a "lxc.apparmor.raw: mount options=(rw,make-rslave) -> **," config option, which is potentialy dangerous as it allows a lot more), but while in stretch systemd just continued, in buster it just fails. Also some other default things like rbind mounting root to "/run/systemd/unit-root/" fails and is not easily possible to allow through apparmor in a sane unproblematic way...
 

t.lamprecht

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Jul 28, 2015
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Yes. Earlier I though of systemd update as the main issue on this, but maybe there is a workaround, or just it is not possible?

For now I'd suggest to downgrade systemd to 239 and pin that one. A colleague is already onto checking a bug in the apparmor parser, which may then help at least for the rslave mount issue.
For the rest I cannot tell anything for sure, besides that until buster gets stable this should get fixed (knocks wood).
 

aalmenar

Member
Jan 12, 2014
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I'd try but that package (systemd_239) is no longer available in testing.... will have to wait for now.

For now I'd suggest to downgrade systemd to 239 and pin that one. A colleague is already onto checking a bug in the apparmor parser, which may then help at least for the rslave mount issue.
For the rest I cannot tell anything for sure, besides that until buster gets stable this should get fixed (knocks wood).
 

sigo

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Aug 24, 2017
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You can enable feature "Nesting" (on tab Options) for LXC container. In my case (I'm also using sid) the same problem was solved.
 
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aalmenar

Member
Jan 12, 2014
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Yes, it's working, at least for now i can continue testing. Thank you.

You can enable feature "Nesting" (on tab Options) for LXC container. In my case (I'm also using sid) the same problem was solved.
 

aalmenar

Member
Jan 12, 2014
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@t.lamprecht should i file a bug on debian on systemd package ?

For now I'd suggest to downgrade systemd to 239 and pin that one. A colleague is already onto checking a bug in the apparmor parser, which may then help at least for the rslave mount issue.
For the rest I cannot tell anything for sure, besides that until buster gets stable this should get fixed (knocks wood).
 

aalmenar

Member
Jan 12, 2014
18
0
21
After filling a bug with debian systemd maintainers the response was this:

Can you disable AppArmor confinement and try again?
(with lxc 3.x that means setting lxc.apparmor.profile = unconfined)

Or use the config options from
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=916644


Please also tell us the lxc and apparmor versions you are using

Looping in the AA mantainer.
 

fabian

Proxmox Staff Member
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Jan 7, 2016
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After filling a bug with debian systemd maintainers the response was this:

Can you disable AppArmor confinement and try again?
(with lxc 3.x that means setting lxc.apparmor.profile = unconfined)

Or use the config options from
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=916644


Please also tell us the lxc and apparmor versions you are using

Looping in the AA mantainer.

I guess you are referring to https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=918839 ? In general it is a good idea to mention that your are not running Debian in a Debian bug report to avoid wasting Debian maintainer time ;) PVE uses a custom LXC build and a different apparmor kernel version and feature set than Debian. In any case, I put some more info into the bug report :)
 
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oguz

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Nov 19, 2018
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I want to understand the security implications of this. Why would I want to run nesting or not?

it lets you mount /proc and /sys and some other stuff in rw mode, which could be dangerous. you're also allowed a greater range of syscalls than regular containers.
 
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