Re: Apparmor (and other) Issues

On Mon, 17 Feb 2025 06:37:18 +0000 Prafulla Giri wrote:

Hello there,

Please forgive me for being MIA.

On Sunday, February 9th, 2025 at 2:53 PM, Stefano Brivio wrote:

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On Sat, 08 Feb 2025 17:19:59 +0000 Prafulla Giri prafulla.giri@protonmail.com wrote:

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On Friday, February 7th, 2025 at 3:01 PM, Stefano Brivio sbrivio@redhat.com wrote:

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On Fri, 07 Feb 2025 06:49:45 +0000 Prafulla Giri prafulla.giri@protonmail.com wrote:

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On Wednesday, February 5th, 2025 at 4:01 PM, Stefano Brivio sbrivio@redhat.com wrote:

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But the libvirt profile is not associated to the process, oops.

Oh, so this is what is being worked upon: that Apparmor is not making the association

That, I'm not sure, but at least Andrea asked openSUSE and Ubuntu people for comments. I just prepared (and merged) a workaround for the moment. You are Cc'ed on the patch. If you want to test it, you should add this:

# Workaround: libvirt's profile comes with a passt subprofile which includes, # in turn, , and adds libvirt-specific rules on top, to

# allow passt (when started by libvirtd) to write socket and PID files in the # location requested by libvirtd itself, and to execute passt itself. # # However, when libvirt runs as unprivileged user, the mechanism based on # virt-aa-helper, designed to build per-VM profiles as guests are started, # doesn't work. The helper needs to create and load profiles on the fly, which # can't be done by unprivileged users, of course. # # As a result, libvirtd runs unconfined if guests are started by unprivileged # users, starting passt unconfined as well, which means that passt runs under # its own stand-alone profile (this one), which implies in turn that execve() # of /usr/bin/passt is not allowed, and socket and PID files can't be written. # # Duplicate libvirt-specific rules here as long as this is not solved in # libvirt's profile itself. /usr/bin/passt r, owner @{run}/user/[0-9]/libvirt/qemu/run/passt/ rw, owner @{run}/libvirt/qemu/passt/* rw,

to your /etc/apparmor.d/usr.bin.passt. Note that changes to AppArmor policy files are retained as configuration, so, if you edit it, package upgrades won't override things automatically. You will need to:

I seem to have botched things up really good, or we're getting into more and more trouble here:

Worry not, I can explain:

You are a very good teacher, I must say.

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1. I have manually `make install`-ed passt (and friends). $ passt version # I don't know what's causing the non-AVX2 thing issue

If you install it to /usr/local/bin, other than adding a profile for /usr/local/bin/passt{,.avx2} as you correctly did, you also need to add the /usr/local/bin path to the "abstraction" that's included by the profile. In /etc/apparmor.d/abstractions/passt we have:

/usr/bin/passt.avx2 ix, # arch_avx2_exec(), arch.c

and if you want to do experiments with a local version that needs to be:

/usr/bin/passt.avx2 ix, # arch_avx2_exec(), arch.c /usr/bin/local/passt.avx2 ix,

I did just that and $ pasta --config-net --trace --pcap /tmp/dns.pcap -- nslookup fsf.org # `which pasta` -> /usr/local/bin/pasta works as expected, thank you.

However, for some reason libvirt still can't run pasta.

You mean 'passt', and:

$ virsh start --domain vm1 rror: Failed to start domain 'vm1' error: internal error: Child process (passt --one-off --socket /run/user/1000/libvirt/qemu/run/passt/2-vm1-net0.socket --pid /run/user/1000/libvirt/qemu/run/passt/2-vm1-net0-passt.pid) unexpected exit status 126: libvirt: error : cannot execute binary passt: Permission denied

It seems adding merely '/usr/bin/local/passt.avx2 ix,' in the abstractions file isn't quite enough. Perhaps there's something missing? Strangely enough, the libvirt-qemu abstraction file does import this abstraction file.

https://salsa.debian.org/sbrivio/passt/-/commit/5bb812e79143670a57440cd8aa7f... might explain it. You need to create hard links ('make install' doesn't do that) to associate different AppArmor profiles. In any case, I'm releasing (and packaging) a new version with the AppArmor workaround today. -- Stefano