Shared memory interface gets link operation denided

[Guillaume Beuzeboc]

I am trying to use the shared-memory feature of FastDDS within a snap (creating shared-memory files in /dev/shm). The idea is to be able to share shared-memory across snaps.

I declared my slot like this:

  slots:
   shmem-slot:
    interface: shared-memory
    write: [fastrtps_*, sem.fastrtps_*]
    private: false

It allows FastDDS to create fastrtps_* files, but fails for sem.fastrtps_* files with this AppArmor log:

  = AppArmor =
  Log: apparmor="DENIED" operation="link" profile="snap.ros2-shared-memory.ros2-talker-listener" name="/dev/shm/sem.fastrtps_port7412_mutex" pid=3881001 comm="listener" requested_mask="l" denied_mask="l" fsuid=1000 ouid=1000 target="/dev/shm/wsRrNj"
  File: /dev/shm/sem.fastrtps_port7412_mutex (write)

After modifying /var/lib/snapd/apparmor/profiles/snap.<name>.<command> and changing the access from rwk to rwlk everything works fine.

Adding the link operation to shared-memory would allow FastDDS and ROS2 users to benefit from the shared-memory transport.

[Alex Murray (alexmurray)]

I have just submitted https://github.com/snapcore/snapd/pull/11812 which should resolve this once it is merged.