[Bug 2052789] Re: AppArmor profiles missing in kernel 5.15.0-1051+ release

[Andreas Hasenack]

Hi all, I'm looking at the focal upload in unapproved.

I see it has this additional change in live-build/functions that is not mentioned in d/changelog:
--- a/live-build/functions
+++ b/live-build/functions
@@ -726,13 +726,44 @@ snap_preseed() {
 
 snap_validate_seed() {
     local CHROOT_ROOT=$1
-
+    local kern_major_min=undefined
+    local boot_filename=undefined
+
+    # ppc64el still uses /boot/vmlinux so we need to determine the boot file name as non ppc64el use /boot/vmlinuz
+    # We don't need to query the arch as we can use existence of the file to determine the boot file name. Both
+    # will never be present at the same time.
+    if [ -e ${CHROOT_ROOT}/boot/vmlinuz ]; then
+        boot_filename=vmlinuz
+    elif [ -e ${CHROOT_ROOT}/boot/vmlinux ]; then
+        boot_filename=vmlinux
+    fi
+    if [ ${boot_filename} != undefined ]; then  # we have a known boot file so we can proceed with checking for features to mount
+        kern_major_min=$(readlink --canonicalize --no-newline ${CHROOT_ROOT}/boot/${boot_filename} | grep  --extended-regexp --only-matching --max-count 1 '[0-9]+\.[0-9]+')
+        if [ -d /usr/share/livecd-rootfs/live-build/apparmor/${kern_major_min} ]; then
+            # if an Ubuntu version has different kernel apparmor features between LTS and HWE kernels
+            # a snap pre-seeding issue can occur, where the incorrect apparmor features are reported
+            # basic copy of a directory structure overriding the "generic" feature set
+            # which is tied to the LTS kernel
+    
+            # Bind kernel apparmor directory to feature directory for snap preseeding
+            umount "${CHROOT_ROOT}/sys/kernel/security/apparmor/features/"
+            mount --bind /usr/share/livecd-rootfs/live-build/apparmor/${kern_major_min} "${CHROOT_ROOT}/sys/kernel/security/apparmor/features/"
+        fi
+    fi 
+    
     if [ -e "${CHROOT_ROOT}/var/lib/snapd/seed/seed.yaml" ]; then
         snap debug validate-seed "${CHROOT_ROOT}/var/lib/snapd/seed/seed.yaml"
         /usr/lib/snapd/snap-preseed --reset $(realpath "${CHROOT_ROOT}")
         /usr/lib/snapd/snap-preseed $(realpath "${CHROOT_ROOT}")
         chroot "${CHROOT_ROOT}" apparmor_parser --skip-read-cache --write-cache --skip-kernel-load --verbose  -j `nproc` /etc/apparmor.d
     fi
+    
+    # Unmount kernel specific apparmor feature
+    # mount generic apparmor feature again (cleanup)
+    if [ -d /build/config/hooks.d/extra/apparmor/${kern_major_min} ]; then
+        umount "${CHROOT_ROOT}/sys/kernel/security/apparmor/features/"
+        mount -o bind /usr/share/livecd-rootfs/live-build/apparmor/generic "${CHROOT_ROOT}/sys/kernel/security/apparmor/features/"
+    fi
 }
 
 snap_from_seed() {


Looking at the jammy code changes and changelog, this seems to fix LP: #2038957):

      * Enable snap preseeding with ppc64el images where /boot/vmlinux is used
        instead of /boot/vmlinuz. (LP: #2038957)

That bug has a focal task, but it was marked as "won't fix" in
https://bugs.launchpad.net/ubuntu/+source/livecd-
rootfs/+bug/2038957/comments/4. Yet here we are with the change.

What do you want to do?
- include this change, and therefore fix #2038957. Then please update d/changelog, and also update the focal task in that other bug and check if its test plan still applies here
- not include the change
- something else because I completely misunderstood this.

Please advise. In the meantime, I'm marking the focal task as
incomplete.

** Changed in: livecd-rootfs (Ubuntu Focal)
       Status: Confirmed => Incomplete

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https://bugs.launchpad.net/bugs/2052789

Title:
  AppArmor profiles missing in kernel 5.15.0-1051+ release

Status in livecd-rootfs package in Ubuntu:
  Fix Committed
Status in livecd-rootfs source package in Focal:
  Incomplete
Status in livecd-rootfs source package in Jammy:
  Fix Committed

Bug description:
  After the kernel roll to linux-gcp-5.15 to version
  5.15.0-1051.59_20.04.1 the public cloud team pre publication test were
  failing on our snap_preseed_optimized test which checks to ensure that
  snaps are preseeded correctly

  This test checks the output of `snap debug seeding` to assert `seed-
  completion` is present and not empty.

  ``
  ❯ snap debug seeding
  seeded:            true
  preseeded:         true
  image-preseeding:  39.367s
  seed-completion:   1.335s
  ```

  If `/var/lib/snapd/seed/seed.yaml` exists it also asserts that
  `preseeded` is present and not empty.

  With the recent kernel update this test is failing which indicates a kernel feature mismatch between
  the running kernel and the feature set hard-coded in livecd-rootfs for this image.
  Boot will be slowed by ~200ms until this is resolved in livecd-rootfs.

  This solution is to add a 5.15 apparmor configuration to the focal
  branch of livecd-rootfs

  The issue is also present with the recent 5.15 kernels in Jammy.

  Related bugs LP: #2031943 and LP: #2045384

  [ Impact ]

  Boot will be slowed by ~200ms until this is resolved in livecd-rootfs

  [ Test Plan ]

   * for focal build any cloud image with preseeded snaps with HWE 5.15 kernel
   * for jammy build any cloud image with preseeded snaps with up to date 5.15 kernel
   * boot
   * run `snap debug seeding`
   * assert the test described above passes

  [ Where problems could occur ]

   * Similar patches already exist for later releases 6.2, 6.5 kernel
  etc. and have been used on other private customer kernels and all
  kernels released after 22.04, so there is already a good track record
  for this patchset and it shouldn't create any issues.

  [ Other Info ]

   * This is a time-sensitive issue for a paying customer

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