FYI, I tested this and 2.13.2-9ubuntu6.1 fixes this bug. I also executed https://wiki.ubuntu.com/Process/Merges/TestPlans/AppArmor (sans dbus optional bits) and everything passed.
Lastly, I wanted to double check the performance impact of no-expr- simplify on amd64 especially as it pertains to cloud and found it was slightly faster for default cloud, lxd and server policy. (It was slower on desktop, as expected and in the expected way due to the somewhat pathological evince profile. This has been the historical acceptable tradeoff to help ARM devices (note that because no-expr- simplify is faster with snap policy, with a handful of additional snaps, desktop breaks even then eventually gets faster too). ** Tags removed: verification-needed verification-needed-disco ** Tags added: verification-done verification-done-disco -- 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/1820068 Title: specifying -O no-expr-simplify results in cache miss Status in AppArmor: Fix Released Status in apparmor package in Ubuntu: Fix Released Status in apparmor source package in Disco: Fix Committed Status in apparmor source package in Eoan: Fix Released Bug description: [Impact] * AppArmor 2.13 unconditionally invalidates its cache when parser options are specified. To decrease compile times for ARM systems, -O no-expr-simplify has been used in Ubuntu for click and snap policy for many years, but was temporarily disabled during the disco development release with the 2.13 upload so caching properly worked everywhere. Now that a simple upstream workaround is available (and already in eoan), we'd like to apply the upstream patch and re-enable -O no-expr-simplify. * A condition of the AppArmor 2.13 feature freeze exception was to fix this bug in SRU to re-enable -O no-expr-simplify. This will help compile times for all architectures with default and typical AppArmor policy (ie, a mixture of (distro) system and snap policy), but especially ARM systems with snaps where the improvement could be in terms of minutes saved. * Specifically, the upstream patch workaround to no longer unconditionally skip reading the cache when parser options are specified. It also re-enables an existing quilt patch to update /etc/apparmor/parser.conf to use no-expr-simplify. [Test Case] # setup $ mkdir -p /tmp/aa/cache /tmp/aa/profiles $ cp /etc/apparmor.d/sbin.dhclient /tmp/aa/profiles/ # no options, no cache, expect a miss and to write $ /sbin/apparmor_parser -k --write-cache --cache-loc=/tmp/aa/cache --skip-kernel-load --add -- /tmp/aa/profiles Cache: added primary location '/tmp/aa/cache' Cache miss: /tmp/aa/profiles/sbin.dhclient Wrote cache: /tmp/aa/cache/26b63962.0/sbin.dhclient # no options, cache, expect a hit $ /sbin/apparmor_parser -k --write-cache --cache-loc=/tmp/aa/cache --skip-kernel-load --add -- /tmp/aa/profiles Cache: added primary location '/tmp/aa/cache' Cache hit: /tmp/aa/cache/26b63962.0/sbin.dhclient # reset $ rm -rf /tmp/aa/cache/* # options, no cache, expect a miss and to write $ /sbin/apparmor_parser -k --write-cache --cache-loc=/tmp/aa/cache --skip-kernel-load -O no-expr-simplify --add -- /tmp/aa/profiles Cache: added primary location '/tmp/aa/cache' Cache miss: /tmp/aa/profiles/sbin.dhclient Wrote cache: /tmp/aa/cache/26b63962.0/sbin.dhclient # options, cache, expect a hit $ /sbin/apparmor_parser -k --write-cache --cache-loc=/tmp/aa/cache --skip-kernel-load -O no-expr-simplify --add -- /tmp/aa/profiles Cache: added primary location '/tmp/aa/cache' Cache miss: /tmp/aa/profiles/sbin.dhclient # SHOULD BE A HIT Wrote cache: /tmp/aa/cache/26b63962.0/sbin.dhclient Same thing happens if omitting -O no-expr-simplify but add Optimize =no-expr-simplify to /etc/apparmor/parser.conf. [Regression Potential] The regression potential is considered low since the patch is simple and easily verifiable. If something went wrong, it would be around cache invalidation which the above test case will demonstrate it works correctly. # Original description With 2.13.2 and the most recent testsuite patches from the 2.13 branch, I find that the cache works correctly when no options are specified. Eg # setup $ mkdir -p /tmp/aa/cache /tmp/aa/profiles $ cp /etc/apparmor.d/sbin.dhclient /tmp/aa/profiles/ # no options, no cache, expect a miss and to write $ /sbin/apparmor_parser -k --write-cache --cache-loc=/tmp/aa/cache --skip-kernel-load --add -- /tmp/aa/profiles Cache: added primary location '/tmp/aa/cache' Cache miss: /tmp/aa/profiles/sbin.dhclient Wrote cache: /tmp/aa/cache/26b63962.0/sbin.dhclient # no options, cache, expect a hit $ /sbin/apparmor_parser -k --write-cache --cache-loc=/tmp/aa/cache --skip-kernel-load --add -- /tmp/aa/profiles Cache: added primary location '/tmp/aa/cache' Cache hit: /tmp/aa/cache/26b63962.0/sbin.dhclient # reset $ rm -rf /tmp/aa/cache/* # options, no cache, expect a miss and to write $ /sbin/apparmor_parser -k --write-cache --cache-loc=/tmp/aa/cache --skip-kernel-load -O no-expr-simplify --add -- /tmp/aa/profiles Cache: added primary location '/tmp/aa/cache' Cache miss: /tmp/aa/profiles/sbin.dhclient Wrote cache: /tmp/aa/cache/26b63962.0/sbin.dhclient # options, cache, expect a hit $ /sbin/apparmor_parser -k --write-cache --cache-loc=/tmp/aa/cache --skip-kernel-load -O no-expr-simplify --add -- /tmp/aa/profiles Cache: added primary location '/tmp/aa/cache' Cache miss: /tmp/aa/profiles/sbin.dhclient # SHOULD BE A HIT Wrote cache: /tmp/aa/cache/26b63962.0/sbin.dhclient Same thing happens if omitting -O no-expr-simplify but add Optimize =no-expr-simplify to /etc/apparmor/parser.conf. 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