Re: [RFC v3 11/22] seccomp,landlock: Handle Landlock hooks per process hierarchy

On Wed, Sep 14, 2016 at 12:24 AM, Mickaël Salaün [off-list ref] wrote:

A Landlock program will be triggered according to its subtype/origin
bitfield. The LANDLOCK_FLAG_ORIGIN_SECCOMP value will trigger the
Landlock program when a seccomp filter will return RET_LANDLOCK.
Moreover, it is possible to return a 16-bit cookie which will be
readable by the Landlock programs in its context.

Are you envisioning that the filters will return RET_LANDLOCK most of
the time or rarely?  If it's most of the time, then maybe this could
be simplified a bit by unconditionally calling the landlock filter and
letting the landlock filter access a struct seccomp_data if needed.

Only seccomp filters loaded from the same thread and before a Landlock
program can trigger it through LANDLOCK_FLAG_ORIGIN_SECCOMP. Multiple
Landlock programs can be triggered by one or more seccomp filters. This
way, each RET_LANDLOCK (with specific cookie) will trigger all the
allowed Landlock programs once.

This interface seems somewhat awkward.  Should we not have a way to
atomicaly install a whole pile of landlock filters and associated
seccomp filter all at once?

--Andy