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Rule downgrades are used to provide some confinement when a feature
is only partially supported by the kernel.
Eg. On a kernel that doesn't support fine grained af_unix mediation
but does support network mediation.
unix (connect, receive, send)
type=stream
peer=(addr="@/tmp/.ICE-unix/[0-9]*"),
will be downgraded to
network unix type=stream,
Which while more permissive still provides some mediation while
allowing the appication to still function. However making the rule
a deny rule result in tightening the profile.
Eg.
deny unix (connect, receive, send)
type=stream
peer=(addr="@/tmp/.ICE-unix/[0-9]*"),
will be downgraded to
deny network unix type=stream,
and that deny rule will take priority over any allow rule. Which means
that if the profile also had unix allow rules they will get blocked by
the downgraded deny rule, because deny rules have a higher priority,
and the application will break. Even worse there is no way to add the
functionality back to the profile without deleting the offending deny
rule.
To fix this we drop deny rules that can't be downgraded in a way that
won't break the application.
Fixes: https://bugzilla.opensuse.org/show_bug.cgi?id=1180766
MR: https://gitlab.com/apparmor/apparmor/-/merge_requests/700
Signed-off-by: John Johansen <john.johansen@canonical.com>
(cherry picked from commit 855dbd4ac8
)
Signed-off-by: John Johansen <john.johansen@canonical.com>
The apparmor_parser allows you to add, replace, and remove AppArmor policy through the use of command line options. The default is to add. `apparmor_parser --help` shows what the command line options are. You can also find more information at https://wiki.apparmor.net -- The AppArmor development team