[PATCH] selinux-policy: update to version v2.0
Stefan Hellermann
stefan at the2masters.de
Mon Jan 13 16:05:18 PST 2025
Hi! Thank you for your really fast changes!
With your last commit f86def7e there are 3 new errors for /dev/urandom:
[...]
[ 1.749370] init: - preinit -
[ 2.437887] audit: type=1400 audit(1736810585.360:3): avc: denied {
getattr } for pid=886 comm="jshn" path="/dev/urandom" dev="tmpfs"
ino=31 scontext=sys.id:sys.role:jshn.subj
tcontext=sys.id:sys.role:random.nodedev tclass=chr_file permissive=1
[ 2.438371] audit: type=1400 audit(1736810585.360:4): avc: denied {
read } for pid=886 comm="jshn" name="urandom" dev="tmpfs" ino=31
scontext=sys.id:sys.role:jshn.subj
tcontext=sys.id:sys.role:random.nodedev tclass=chr_file permissive=1
[ 2.439138] audit: type=1400 audit(1736810585.360:5): avc: denied {
open } for pid=886 comm="jshn" path="/dev/urandom" dev="tmpfs" ino=31
scontext=sys.id:sys.role:jshn.subj
tcontext=sys.id:sys.role:random.nodedev tclass=chr_file permissive=1
[ 4.994969] random: crng init done
[...]
And I cannot login on ttyAMA0:
Please press Enter to activate this console.
login: can't get SID for root
Login with ssh is ok. There is already a bug report for this, it's
working fine without selinux:
https://github.com/openwrt/openwrt/issues/17038
After sysupgrade the "sysupgrade.tgz" error remains the same:
[ 12.155085] audit: type=1400 audit(1736811933.100:6): avc: denied {
associate } for pid=1006 comm="mv" name="sysupgrade.tgz"
scontext=sys.id:sys.role:dos.fs tcontext=sys.id:sys.role:xattr.fs
tclass=filesystem permissive=1
And while doing sysupgrade from a local file in /tmp I get a bunch more
(no luci here, just scp file to /tmp and start sysupgrade from ssh):
[ 74.345700] audit: type=1400 audit(1736811834.460:6): avc: denied {
read write } for pid=2854 comm="fwtool"
name="openwrt-armsr-armv8-generic-squashfs-combined.img.gz" dev="tmpfs"
ino=93 scontext=sys.id:sys.role:fwtool.subj
tcontext=sys.id:sys.role:ssh.server.hostkey.file tclass=file permissive=1
[ 74.347589] audit: type=1400 audit(1736811834.460:7): avc: denied {
open } for pid=2854 comm="fwtool"
path="/tmp/openwrt-armsr-armv8-generic-squashfs-combined.img.gz"
dev="tmpfs" ino=93 scontext=sys.id:sys.role:fwtool.subj
tcontext=sys.id:sys.role:ssh.server.hostkey.file tclass=file permissive=1
[ 74.349106] audit: type=1400 audit(1736811834.460:8): avc: denied {
ioctl } for pid=2854 comm="fwtool"
path="/tmp/openwrt-armsr-armv8-generic-squashfs-combined.img.gz"
dev="tmpfs" ino=93 ioctlcmd=0x5413 scontext=sys.id:sys.role:fwtool.subj
tcontext=sys.id:sys.role:ssh.server.hostkey.file tclass=file permissive=1
[ 74.770422] audit: type=1400 audit(1736811834.890:9): avc: denied {
read } for pid=2864 comm="cat" name="cmdline" dev="proc" ino=4026531972
scontext=sys.id:sys.role:validatefirmwareimage.subj
tcontext=sys.id:sys.role:cmdline.procfile tclass=file permissive=1
[ 74.771728] audit: type=1400 audit(1736811834.890:10): avc: denied {
open } for pid=2864 comm="cat" path="/proc/cmdline" dev="proc"
ino=4026531972 scontext=sys.id:sys.role:validatefirmwareimage.subj
tcontext=sys.id:sys.role:cmdline.procfile tclass=file permissive=1
[ 74.800695] audit: type=1400 audit(1736811834.920:11): avc: denied {
read } for pid=2865 comm="find" name="/" dev="tmpfs" ino=1
scontext=sys.id:sys.role:validatefirmwareimage.subj
tcontext=sys.id:sys.role:tmp.fs tclass=dir permissive=1
[ 74.801449] audit: type=1400 audit(1736811834.920:12): avc: denied {
open } for pid=2865 comm="find" path="/dev" dev="tmpfs" ino=1
scontext=sys.id:sys.role:validatefirmwareimage.subj
tcontext=sys.id:sys.role:tmp.fs tclass=dir permissive=1
[ 74.807108] audit: type=1400 audit(1736811834.930:13): avc: denied {
getattr } for pid=2865 comm="find" path="/dev/pts" dev="devpts" ino=1
scontext=sys.id:sys.role:validatefirmwareimage.subj
tcontext=sys.id:sys.role:devpts.fs tclass=dir permissive=1
[ 74.807988] audit: type=1400 audit(1736811834.930:14): avc: denied {
read } for pid=2865 comm="find" name="/" dev="devpts" ino=1
scontext=sys.id:sys.role:validatefirmwareimage.subj
tcontext=sys.id:sys.role:devpts.fs tclass=dir permissive=1
[ 74.808726] audit: type=1400 audit(1736811834.930:15): avc: denied {
open } for pid=2865 comm="find" path="/dev/pts" dev="devpts" ino=1
scontext=sys.id:sys.role:validatefirmwareimage.subj
tcontext=sys.id:sys.role:devpts.fs tclass=dir permissive=1
[ 80.140951] kauditd_printk_skb: 35 callbacks suppressed
[ 80.140985] audit: type=1400 audit(1736811840.260:51): avc: denied {
remove_name } for pid=3459 comm="rm" name="image.bs" dev="tmpfs" ino=96
scontext=sys.id:sys.role:validatefirmwareimage.subj
tcontext=sys.id:sys.role:tmp.fs tclass=dir permissive=1
[ 80.141666] audit: type=1400 audit(1736811840.260:52): avc: denied {
unlink } for pid=3459 comm="rm" name="image.bs" dev="tmpfs" ino=96
scontext=sys.id:sys.role:validatefirmwareimage.subj
tcontext=sys.id:sys.role:tmp.fs tclass=file permissive=1
[ 87.255570] audit: type=1400 audit(1736811847.370:53): avc: denied {
getattr } for pid=3955 comm="find" path="/dev/hwrng" dev="tmpfs" ino=14
scontext=sys.id:sys.role:validatefirmwareimage.subj
tcontext=sys.id:sys.role:hwrng.nodedev tclass=chr_file permissive=1
This is all done on a fresh openwrt checkout, I added your selinux
updates and build the image with this config:
CONFIG_TARGET_armsr=y
CONFIG_TARGET_armsr_armv8=y
CONFIG_TARGET_armsr_armv8_DEVICE_generic=y
CONFIG_PACKAGE_qemu-ga=y
CONFIG_SELINUX=y
I can send you the compressed image file, if you want to try it yourself
with qemu/virt-manager.
Regards,
Stefan Hellermann
Am 13.01.25 um 18:52 schrieb Dominick Grift:
> Dominick Grift <dominick.grift at defensec.nl> writes:
>
>> Dominick Grift <dominick.grift at defensec.nl> writes:
>>
>>> Hi, Thank you for feedback. Comments inline below:
>>>
>>> Stefan Hellermann <stefan at the2masters.de> writes:
>>>
>> <snip>
>>
>>>> audit(1736704702.290:4): avc: denied { associate } for pid=1010
>>>> comm="mv" name="sysupgrade.tgz" scontext=sys.id:sys.role:dos.fs
>>>> tcontext=sys.id:sys.role:xattr.fs tclass=filesystem permissive=1
>>> This is caused by mv'ing the file from a fat filesystem (fat does not
>>> support extended attributes) to an extended attribute file system. When
>>> you mv a file you also mv its associated context with it.
>>>
>>> This should not be allowed. Instead you should use cp. mv does not make
>>> much sense anyway cross filesystem.
>>>
>> This bothered me so I would like to explain why I object to this.
>>
>> mv and cp are more complicated than some think. I see this all the time
>> where people for example use `cp -a` without realizing the consequences.
>>
>> But regardless of this, coreutils has extensive support for SELinux and
>> `mv -Z` would have addressed the above challenge. The issue is that
>> busybox' `mv` does not support -Z and so eventually I will have to draw
>> the line somewhere anyway. This seems like a good place to start.
>>
>>>> Sun Jan 12 17:58:25 2025 user.warn kernel: urandom-seed: Seed file not
>>>> found (/etc/urandom.seed)
>>>> Sun Jan 12 17:58:25 2025 user.info kernel: procd: - early -
>>>> Sun Jan 12 17:58:25 2025 kern.notice kernel: audit: type=1400
>>>> audit(1736704702.590:5): avc: denied { write } for pid=1166
>>>> comm="mkdir" name="/" dev="tmpfs" ino=1
>>>> scontext=sys.id:sys.role:hotplug.call.subj
>>>> tcontext=sys.id:sys.role:tmp.fs tclass=dir permissive=1
>>>> Sun Jan 12 17:58:25 2025 kern.notice kernel: audit: type=1400
>>>> audit(1736704702.590:6): avc: denied { add_name } for pid=1166
>>>> comm="mkdir" name="virtio-ports"
>>>> scontext=sys.id:sys.role:hotplug.call.subj
>>>> tcontext=sys.id:sys.role:tmp.fs tclass=dir permissive=1
>>>> Sun Jan 12 17:58:25 2025 kern.notice kernel: audit: type=1400
>>>> audit(1736704702.590:7): avc: denied { create } for pid=1166
>>>> comm="mkdir" name="virtio-ports"
>>>> scontext=sys.id:sys.role:hotplug.call.subj
>>>> tcontext=sys.id:sys.role:tmp.fs tclass=dir permissive=1
>>>> Sun Jan 12 17:58:25 2025 kern.notice kernel: audit: type=1400
>>>> audit(1736704702.590:8): avc: denied { create } for pid=1167
>>>> comm="ln" name="org.qemu.guest_agent.0"
>>>> scontext=sys.id:sys.role:hotplug.call.subj
>>>> tcontext=sys.id:sys.role:tmp.fs tclass=lnk_file permissive=1
>>>> Sun Jan 12 17:58:25 2025 user.info kernel: procd: - ubus -
>>>> Sun Jan 12 17:58:25 2025 user.info kernel: procd: - init -
> I added support for this. We'll see where this leads. I might end up
> reverting it later.
>
> https://git.defensec.nl/?p=selinux-policy.git;a=commitdiff;h=32c0cc897f679b6d2b204bc2935d9de3b7006944
>
>>> This seems like an 'exotic hotplug script'. I have an accomodation for
>>> this. see if this comment helps:
>>> https://git.defensec.nl/?p=selinux-policy.git;a=blob;f=src/agent/sysagent/hotplugsysagent.cil;h=3987b8540ae537d174a74cceb2c89ce26ef3c813;hb=HEAD#l115
>> We'll have to see how this will work out practically. I am open to
>> suggestions for alternative approaches but this seems like a fair
>> approach.
>>
>> There are also challenges here. For example in the above event, the
>> script is trying to create a dir and symlink in /dev. In OpenWrt there
>> is no (easy) way to make a distinction between devtmpfs and and a common
>> tmpfs. If I we're to allow this then that would later potentially
>> present challenges when another script wants to create a dir or symlink in /tmp.
>>
>> Again, eventually I would have to draw the line somewhere as to what
>> should be allowed by default and what is to be considered exotic. This
>> looks like a good place.
>>
>> Just trying to explain some of the rationale because I am open to better
>> alternatives. I just don't see any.
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