** Description changed: Hi, to be clear I consider it quite likely that the error is on my side, but I'd appreciate guidance how to continue resolve. I have rubber ducked my setup with a coworker and talked to jjohansen if the profile would contain an obvious fault (it did not). So hereby I'm filing a bug hoping to get some help on this case. ## 1. What happened I was trying to add a feature to libvirt to support chained qcow files. That means instead of adding just one path libvirt has to process the chain of backing files and add all of those. That works already on guest start, but not on hot-add of devices. But while I see my code appending the rules I'd expect and issuing the apparmor_parser calls I'd expect it still fails. I'd love to get the profile at runtime to ensure things really are loaded as expected. But as discussed on IRC that won't work. So I tested and simplified and wonder for the test below why things fail. ## 2. how to reproduce - I was taking my new code out of the equation - and to do so I was adding - the path that is needed to the local overrides. But it still is blocked. - So - right now - I'm assuming that my code worked in adding the lines, - but the access is still blocked. Therefore let us try to fix this one - first and only then I can debug into what might be failing on the new - code. + I was debugging various cases (see below updates) and found that just one + combination fails (also see comment #5) + I'm rather sure now that libvirt adds the path correctly, but even + adding the denied path that is needed to the local overrides does not + help. + + Use a Hirsute Container and enable this PPA: + https://launchpad.net/~ci-train-ppa-service/+archive/ubuntu/4393 + + Then - to underline that the rule should be ok also add it manually as local override. # Allow the access that libvirt does not yet allow $ echo '"/var/lib/libvirt/images/testdisk-snap-snapshot.qcow2" rwk,' > /etc/apparmor.d/local/abstractions/libvirt-qemu + $ echo '"/var/lib/libvirt/images/testdisk-snap-base.qcow2" rwk,' >> /etc/apparmor.d/local/abstractions/libvirt-qem + + # Check the profile can be loaded and contains these + $ apparmor_parser -r /etc/apparmor.d/libvirt/libvirt-85410987-d91b-487a-8f2c-911f0136c877 + $ apparmor_parser -p /etc/apparmor.d/libvirt/libvirt-85410987-d91b-487a-8f2c-911f0136c877 | grep snap + "/var/lib/libvirt/images/testdisk-snap-snapshot.qcow2" rwk, + "/var/lib/libvirt/images/testdisk-snap-base.qcow2" rwk, + # prep the disk chain to be hot-added qemu-img create -f qcow2 /var/lib/libvirt/images/testdisk-snap-base.qcow2 100M qemu-img create -f qcow2 -b /var/lib/libvirt/images/testdisk-snap-base.qcow2 /var/lib/libvirt/images/testdisk-snap-snapshot.qcow2 cat > hot-add-test.xml << EOF <disk type='file' device='disk'> <driver name='qemu' type='qcow2'/> <source file='/var/lib/libvirt/images/testdisk-snap-snapshot.qcow2' index='1'/> <backingStore type='file' index='2'> <format type='qcow2'/> <source file='/var/lib/libvirt/images/testdisk-snap-base.qcow2'/> <backingStore/> </backingStore> <target dev='vdc' bus='virtio'/> </disk> EOF - # prep a guest to attach to + # prep a guest to attach the disk to uvt-simplestreams-libvirt --verbose sync --source http://cloud-images.ubuntu.com/daily arch=amd64 label=daily release=focal uvt-kvm create --host-passthrough --password=ubuntu f-test2 release=focal arch=amd64 label=daily We have checked the "effective" profile that is loaded. JJohanssen didn't see an obvious flaw in it. But for reference here: root@h-libvirt-orig:~# apparmor_parser -p /etc/apparmor.d/libvirt/libvirt-e033b910-be06-4975-826f-b6fba368d928 | pastebinit https://paste.ubuntu.com/p/yxdmMT6638/ # attach the disk virsh attach-device f-test2 hot-add-test.xml - Libvirt/Qemu works as usual - except (known and expected) does not add a rule for "/var/lib/libvirt/images/testdisk-snap-snapshot.qcow2". But for that we have added out local override. - Yet it is denied access. + Libvirt (as usual) now adds rules for the image file. + With the new code from the PPA it does so twice - once for the snapshot and once the base file. + But in any case we allow that access through our override. + You can see that on a little gimmick, since the flattened profile always has those rules - and when libvirt is adding them we will sometimes now see info="same as current profile, skipping". + If the local override isn't in place that does not show up. + So the rules libvirt adds are identical to what we have put into the local override and that should allow the access. - apparmor="DENIED" operation="open" namespace="root//lxd-h-libvirt-new_ - <var-snap-lxd-common-lxd>" profile="libvirt-a2caaf89-0682-464d-92ba- - 5295cb5f5128" name="/var/lib/libvirt/images/testdisk-snap- - snapshot.qcow2" pid=2889044 comm="qemu-system-x86" requested_mask="r" - denied_mask="r" fsuid=64055 ouid=64055 + But we get: - ## 3. The rule is generally working + [699826.573035] audit: type=1400 audit(1611044559.393:2047): + apparmor="DENIED" operation="open" namespace="root//lxd-h-libvirt-new2_ + <var-snap-lxd-common-lxd>" profile="libvirt-85410987-d91b-487a-8f2c- + 911f0136c877" name="/var/lib/libvirt/images/testdisk-snap-base.qcow2" + pid=111701 comm="qemu-system-x86" requested_mask="r" denied_mask="r" + fsuid=64055 ouid=64055 - To be clear, on the same system if I just open up a new profile and allow this path to be accessed it works fine. See the working example below. - It must be somewhat that is tied to the way KVM guests get their profile updates/assigned. - root@h-libvirt-orig:~# cat /etc/apparmor.d/test - #include <tunables/global> - - profile test flags=(attach_disconnected) { - #include <abstractions/base> - - "/var/lib/libvirt/images/testdisk-snap-snapshot.qcow2" rwk, - "/usr/bin/md5sum" rmix, - } - root@h-libvirt-orig:~# apparmor_parser -r /etc/apparmor.d/test; aa-exec -v -p test -- md5sum /var/lib/libvirt/images/testdisk-snap-snapshot.qcow2 - [6939] aa_change_onexec("test") - [6939] exec md5sum /var/lib/libvirt/images/testdisk-snap-snapshot.qcow2 - 0f7fc62d270b69ee1b51453fa614d3e4 /var/lib/libvirt/images/testdisk-snap-snapshot.qcow2 - root@h-libvirt-orig:~# apparmor_parser -r /etc/apparmor.d/test; aa-exec -v -p test -- md5sum /var/lib/libvirt/images/testdisk-snap-base.qcow2 - [6944] aa_change_onexec("test") - [6944] exec md5sum /var/lib/libvirt/images/testdisk-snap-base.qcow2 - md5sum: /var/lib/libvirt/images/testdisk-snap-base.qcow2: Permission denied - - ## 4. tracking apparmor_parser + ## 3. tracking apparmor_parser I was using (for debug) a wrapper for apparmro_parser but all really looks as expected $ cat /usr/sbin/apparmor_parser.wrap #!/bin/bash echo "ARGS $@" | /usr/bin/systemd-cat echo "Content of ${2}:" | /usr/bin/systemd-cat /usr/bin/ls -laF "${2}" | /usr/bin/systemd-cat /usr/bin/cat "${2}" | /usr/bin/systemd-cat echo "Content of ${2}.files:" | /usr/bin/systemd-cat /usr/bin/ls -laF "${2}.files" | /usr/bin/systemd-cat /usr/bin/cat "${2}.files" | /usr/bin/systemd-cat /usr/sbin/apparmor_parser.orig "$@" | /usr/bin/systemd-cat It is called with "-r filepath" and the content of that filepath contain the aforementioned rules. So what else might be wrong - why else could the access be denied despite the rule that should allow it. + + + ## "special combination" + + As explained in later comments it works on bare metal, it works with the old libvirt code, it works if attaching one disk (no two calls to apparmor_parser from libvirt), it works if I do the same manually. + But still the bad case fails - puzzling - please help.
-- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to apparmor in Ubuntu. https://bugs.launchpad.net/bugs/1912214 Title: qemu can't access files that are added as rules on hot-add Status in apparmor package in Ubuntu: New Bug description: Hi, to be clear I consider it quite likely that the error is on my side, but I'd appreciate guidance how to continue resolve. I have rubber ducked my setup with a coworker and talked to jjohansen if the profile would contain an obvious fault (it did not). So hereby I'm filing a bug hoping to get some help on this case. ## 1. What happened I was trying to add a feature to libvirt to support chained qcow files. That means instead of adding just one path libvirt has to process the chain of backing files and add all of those. That works already on guest start, but not on hot-add of devices. But while I see my code appending the rules I'd expect and issuing the apparmor_parser calls I'd expect it still fails. I'd love to get the profile at runtime to ensure things really are loaded as expected. But as discussed on IRC that won't work. So I tested and simplified and wonder for the test below why things fail. ## 2. how to reproduce I was debugging various cases (see below updates) and found that just one combination fails (also see comment #5) I'm rather sure now that libvirt adds the path correctly, but even adding the denied path that is needed to the local overrides does not help. Use a Hirsute Container and enable this PPA: https://launchpad.net/~ci-train-ppa-service/+archive/ubuntu/4393 Then - to underline that the rule should be ok also add it manually as local override. # Allow the access that libvirt does not yet allow $ echo '"/var/lib/libvirt/images/testdisk-snap-snapshot.qcow2" rwk,' > /etc/apparmor.d/local/abstractions/libvirt-qemu $ echo '"/var/lib/libvirt/images/testdisk-snap-base.qcow2" rwk,' >> /etc/apparmor.d/local/abstractions/libvirt-qem # Check the profile can be loaded and contains these $ apparmor_parser -r /etc/apparmor.d/libvirt/libvirt-85410987-d91b-487a-8f2c-911f0136c877 $ apparmor_parser -p /etc/apparmor.d/libvirt/libvirt-85410987-d91b-487a-8f2c-911f0136c877 | grep snap "/var/lib/libvirt/images/testdisk-snap-snapshot.qcow2" rwk, "/var/lib/libvirt/images/testdisk-snap-base.qcow2" rwk, # prep the disk chain to be hot-added qemu-img create -f qcow2 /var/lib/libvirt/images/testdisk-snap-base.qcow2 100M qemu-img create -f qcow2 -b /var/lib/libvirt/images/testdisk-snap-base.qcow2 /var/lib/libvirt/images/testdisk-snap-snapshot.qcow2 cat > hot-add-test.xml << EOF <disk type='file' device='disk'> <driver name='qemu' type='qcow2'/> <source file='/var/lib/libvirt/images/testdisk-snap-snapshot.qcow2' index='1'/> <backingStore type='file' index='2'> <format type='qcow2'/> <source file='/var/lib/libvirt/images/testdisk-snap-base.qcow2'/> <backingStore/> </backingStore> <target dev='vdc' bus='virtio'/> </disk> EOF # prep a guest to attach the disk to uvt-simplestreams-libvirt --verbose sync --source http://cloud-images.ubuntu.com/daily arch=amd64 label=daily release=focal uvt-kvm create --host-passthrough --password=ubuntu f-test2 release=focal arch=amd64 label=daily We have checked the "effective" profile that is loaded. JJohanssen didn't see an obvious flaw in it. But for reference here: root@h-libvirt-orig:~# apparmor_parser -p /etc/apparmor.d/libvirt/libvirt-e033b910-be06-4975-826f-b6fba368d928 | pastebinit https://paste.ubuntu.com/p/yxdmMT6638/ # attach the disk virsh attach-device f-test2 hot-add-test.xml Libvirt (as usual) now adds rules for the image file. With the new code from the PPA it does so twice - once for the snapshot and once the base file. But in any case we allow that access through our override. You can see that on a little gimmick, since the flattened profile always has those rules - and when libvirt is adding them we will sometimes now see info="same as current profile, skipping". If the local override isn't in place that does not show up. So the rules libvirt adds are identical to what we have put into the local override and that should allow the access. But we get: [699826.573035] audit: type=1400 audit(1611044559.393:2047): apparmor="DENIED" operation="open" namespace="root//lxd-h-libvirt- new2_<var-snap-lxd-common-lxd>" profile="libvirt-85410987-d91b-487a- 8f2c-911f0136c877" name="/var/lib/libvirt/images/testdisk-snap- base.qcow2" pid=111701 comm="qemu-system-x86" requested_mask="r" denied_mask="r" fsuid=64055 ouid=64055 ## 3. tracking apparmor_parser I was using (for debug) a wrapper for apparmro_parser but all really looks as expected $ cat /usr/sbin/apparmor_parser.wrap #!/bin/bash echo "ARGS $@" | /usr/bin/systemd-cat echo "Content of ${2}:" | /usr/bin/systemd-cat /usr/bin/ls -laF "${2}" | /usr/bin/systemd-cat /usr/bin/cat "${2}" | /usr/bin/systemd-cat echo "Content of ${2}.files:" | /usr/bin/systemd-cat /usr/bin/ls -laF "${2}.files" | /usr/bin/systemd-cat /usr/bin/cat "${2}.files" | /usr/bin/systemd-cat /usr/sbin/apparmor_parser.orig "$@" | /usr/bin/systemd-cat It is called with "-r filepath" and the content of that filepath contain the aforementioned rules. So what else might be wrong - why else could the access be denied despite the rule that should allow it. ## "special combination" As explained in later comments it works on bare metal, it works with the old libvirt code, it works if attaching one disk (no two calls to apparmor_parser from libvirt), it works if I do the same manually. But still the bad case fails - puzzling - please help. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/apparmor/+bug/1912214/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp
