aa-easyprof: allow mmap and link from easyprof generated profiles

[Ratchanan Srirattanamet]

Currently, an easyprof-generated profile will list the reads with `rk` and the writes as `rwk`. With recent Qt, this breaks because newer Qt versions use hard-linking of temporary files to perform atomic writes. Also, `rk` doesn't allow mmap()'ing shared library for execution.

We at UBports are carrying a patch in Ubuntu Touch which changes the read rules to `mrk` and write rules to `mrwkl`, and are upstreaming this patch at [1]. When the MR is merged, I would like this patch to be included in Ubuntu 24.04, so that Ubuntu Touch doesn't have to package AppArmor separately from Ubuntu.

If we agree that we want this patch, I can provide an MR on Salsa.

[1] https://gitlab.com/apparmor/apparmor/-/merge_requests/1189

[Seth Arnold (seth-arnold)]

The 'm' permission shouldn't be a default; restricting what the CPU will execute is a very useful security mitigation.

Thanks

[Ratchanan Srirattanamet (peat-new)]

Hmm... indeed! I'll re-investigate why we need `m` permission by the default. I assume that if there's something that actually need `m` permission, a new key in the easyprof manifest would be needed, right?

As for `l` rule for writes, do you think it's safe to add? Given that "the new link MUST have a subset of permissions as the original file" [1], this shouldn't be able to be used to open up more permission.

[1]: https://manpages.debian.org/bookworm/apparmor/apparmor.d.5.en.html#l~2