Re: [PATCH] contrib/selinux: use regex instead of non-standard bash macro

[Danish Prakash <contact@danishpraka.sh>]

On 10/29/25 4:47 AM, Stefano Brivio wrote:
> On Tue, 28 Oct 2025 11:58:18 +0530
> Danish Prakash <contact@danishpraka.sh> wrote:
> 
>> On 10/27/25 2:37 PM, Stefano Brivio wrote:
>>> Hi Danish,
>>>
>>> On Mon, 27 Oct 2025 14:19:14 +0530
>>> Danish Prakash <contact@danishpraka.sh> wrote:
>>>   
>>>> On 10/16/25 4:26 PM, Max Chernoff wrote:  
>>>>> Hi Stefano,
>>>>>
>>>>> On Thu, 2025-10-16 at 10:21 +0200, Stefano Brivio wrote:    
>>>>>> On Thu, 16 Oct 2025 13:10:41 +0530
>>>>>> Danish Prakash <contact@danishpraka.sh> wrote:    
>>>>>>> It might be possible to avoid using non-standard bash macro (%USERID),    
>>>>>
>>>>> It's not a Bash macro, it's a SELinux template. This doesn't seem to be
>>>>> documented anywhere (which isn't terribly surprising with SELinux), but
>>>>> it's defined in this file:
>>>>>
>>>>>     https://github.com/SELinuxProject/selinux/blob/ceb5b221/libsemanage/src/genhomedircon.c    
>>>>
>>>> Thanks Max, I wasn't aware of it being an SELinux template.
>>>>  
>>>>>     
>>>>>> I wonder if
>>>>>> Max remembers any reason why we couldn't do this in the first place.    
>>>>>
>>>>> The Fedora SELinux policy always uses %{USERID}, and so I copied it from
>>>>> there:
>>>>>
>>>>>     $ grep -RnF '%{USERID}' policy/
>>>>>     policy/modules/contrib/dbus.fc:29:/run/user/%{USERID}/bus	-s	gen_context(system_u:object_r:session_dbusd_tmp_t,s0)
>>>>>     policy/modules/contrib/dbus.fc:30:/run/user/%{USERID}/dbus(/.*)? 	gen_context(system_u:object_r:session_dbusd_tmp_t,s0)
>>>>>     policy/modules/contrib/dbus.fc:31:/run/user/%{USERID}/dbus-1(/.*)? 	gen_context(system_u:object_r:session_dbusd_tmp_t,s0)
>>>>>     policy/modules/contrib/gnome.fc:25:/run/user/%{USERID}/\.orc(/.*)?		gen_context(system_u:object_r:gstreamer_home_t,s0)
>>>>>     policy/modules/contrib/gnome.fc:26:/run/user/%{USERID}/dconf(/.*)?	gen_context(system_u:object_r:config_home_t,s0)
>>>>>     policy/modules/contrib/gnome.fc:27:/run/user/%{USERID}/keyring.*	gen_context(system_u:object_r:gkeyringd_tmp_t,s0)
>>>>>     policy/modules/kernel/filesystem.fc:17:/run/user/%{USERID}/gvfs		-d	gen_context(system_u:object_r:fusefs_t,s0)
>>>>>     policy/modules/kernel/filesystem.fc:18:/run/user/%{USERID}/gvfs/.*	<<none>>
>>>>>     policy/modules/system/userdomain.fc:38:/run/user/%{USERID}	-d	gen_context(system_u:object_r:user_tmp_t,s0)
>>>>>     policy/modules/system/userdomain.fc:39:/run/user/%{USERID}/.+	<<none>>
>>>>>
>>>>>     $ grep -RnF '[0-9]+' policy/  | grep -v /dev/
>>>>>     policy/modules/contrib/rpm.fc:52:/usr/bin/rhn_check-[0-9]+\.[0-9]+		--	gen_context(system_u:object_r:rpm_exec_t,s0)
>>>>>     policy/modules/contrib/soundserver.fc:12:/run/yiff-[0-9]+\.pid	--	gen_context(system_u:object_r:soundd_var_run_t,s0)
>>>>>     policy/modules/kernel/devices.if:6958:##	Allow read the hfi1_[0-9]+ devices
>>>>>     
>>>>>>> diff --git a/contrib/fedora/passt.spec b/contrib/fedora/passt.spec
>>>>>>> index 663289f53d97..d1bcf4a74338 100644
>>>>>>> --- a/contrib/fedora/passt.spec
>>>>>>> +++ b/contrib/fedora/passt.spec
>>>>>>> [...]    
>>>>>>
>>>>>> At a glance, this looks like a better solution regardless of the
>>>>>> reported issue. It sounds too good to be true, though    
>>>>>
>>>>> I agree that it looks like a good solution, which makes me wonder why
>>>>> the base SELinux policies don't do it that way. The containers SELinux
>>>>> policy appears to do things this way
>>>>>
>>>>>     $ grep -RnF '[0-9]+'
>>>>>     container_selinux.8:166:	/run/user/[0-9]+/gvfs
>>>>>     $ grep -RnF '%{USERID}'; echo $?
>>>>>     1
>>>>>
>>>>> so it's probably (?) okay though.    
>>>>
>>>> That's helpful, I guess we can go ahead with this. Stefano, Paul?  
>>>
>>> Sure. But back to my question about the original problem... what was
>>> the original problem? :) Could it be something similar to:
>>>
>>>   https://bugzilla.redhat.com/show_bug.cgi?id=2401764
>>>
>>> ?  
>>
>> Ah, sorry about that. No, it's not a functionality issue or a bug. It
>> was merely a few suggestions to improve the passt SUSE package from the
>> SELinux team at SUSE. Here are the suggestions:
> 
> Thanks for sharing those.
> 
>> 1. building twice is quite a hack, setting a hardlink as in apparmor
>> would probably work as well and is less confusing
> 
> Details as to why it doesn't work:
> 
>   https://passt.top/passt/commit/?id=a405d0c026582375448fe87c6e440eb0fd428dd7
> 
>> 2.  running restorecon would be unnecessary if the passt upstream
>> selinux module would not use ${USERID} in pasta.fc (gets converted to
>> [0-9]+ anyway)
> 
> Would you be so kind as to re-post this patch (Cc'ing Max and Paul) with
> a commit message reflecting this, and without private links?

Sent updated patch, I wonder why it didn't show up in this thread, I did
include the message-id of the original message.

> 
>> 3. there is a %selinux_requires macro in selinux-policy-devel that
>> likely could be used instead of listing the Requires:, but okay we dont
>> enforce that atm
>>
>> For #1 I can see that building twice is required in this case, and
>> unlike apparmor which can work with hardlinks, doing the same for
>> SELinux isn't possible with inodes in the picture.
> 
> Right, yeah, it's because labels are stored in extended attributes, and
> those belong to inodes, not paths.
> 
>> #2 is what this patch is about, and #3 is SUSE-exclusive which I'm
>> fixing in parallel.
> 
> If I recall correctly, that part of openSUSE spec file is roughly taken
> from:
> 
>   https://passt.top/passt/tree/contrib/fedora/passt.spec
> 
> and I build openSUSE packages in my Copr repository too
> (https://copr.fedorainfracloud.org/coprs/sbrivio/passt/), based on the
> Fedora spec file.
> 
> I'm not sure if it's useful for many people (one can try out an
> upstream release right away like that) but it's almost zero effort on
> my side. In any case, if the change also applies to Fedora or openSUSE
> packages from Copr I guess it would be nice to have a patch for that as
> well.

Yes, the spec is taken from fedora. And now that you mention it, I can
see there's a similar %selinux_requires macro in fedora as well--taken
by openSUSE presumably. So I guess, I can send that change across as well.

> 
>>> In general, there are a bunch of current SELinux issues reported on
>>> Fedora/RHEL (and I assume they would be exactly the same on
>>> openSUSE/SLES):
>>>
>>>   https://bugzilla.redhat.com/buglist.cgi?bug_status=__open__&columnlist=short_desc%2Cchangeddate%2Cbug_severity&component=passt&product=Fedora
>>>
>>> and I'm trying to find out if this change might fix some of them. Most
>>> of those are stuff I didn't investigate yet.
>>>   
>>
>> Unfortunately no, I was notified of a few spec related errors from
>> colleagues, but I'm sure the errors would overlap, as you said. If
>> there's something I can help, please let me know, I'll be happy to
>> contribute.
> 
> Thanks. I still need to find a moment to go through all of them with a
> bit more time and I'll let you know, in case.
> 
> Well, of course, if you want to have a look meanwhile, that might help.
> You would need an account at bugzilla.redhat.com to comment but, well, I
> have an account on bugzilla.suse.com, so... :)
> 

Happy to help, I'll create that coveted account :)

-- 
danishpraka.sh