Joshua Brindle wrote:
Stephen Smalley wrote:
This is likely my fault, but we're encountering increasing
problems from growth in the set of things that depend on the
static libsepol whenever we make a change to libsepol,
particularly a policy version change. We now have (at least)
the following dependencies on it:
checkpolicy (always true, not likely to go away) libselinux
(for the audit2why python binding module, which used to be
its own utility in policycoreutils) setools
Does slide also have this dependency or is it clean? Anything else to
worry about?
The result is that when a newer libsepol gets incorporated
and libselinux or setools does not, we encounter breakage
(unable to find a policy file they can read or unable to read
the policy file at which they are pointed) or confusion
(reading an older policy file left around from before the
libsepol update) upon trying to use audit2why or setools.
We ran into this problem twice in rawhide / F9, once upon the
policy capability support (policy.22) and now for permissive types
(policy.23).
Only real way forward that I can see it to actually
encapsulate the interfaces required by audit2why and setools
so that they can use the shared libsepol.
One thing that we are doing for policyrep is encapsulating all the "add
this kind of thing to a policydb" functionality because we didn't want
policyrep users to be static libsepol users.
This has multiple disadvantages including its huge, it is slow (7 hash
lookups to add an av rule currently, since its string based) and doesn't
include the other functionality like the security server, query
functions that would be required for audit2why and setools.
After going through that effort and seeing the pain first hand I
honestly think it is a better alternative to forgo encapsulation and
just make the policydb public. Not yet though, since we ripped out all
the module stuff in it for policyrep. Since it is returning to a more
pristine state that can't realistically change much in the future maybe
it would be better for everyone to rip out the encapsulation as well.
What are your thoughts on this Steve? Karl agrees with me, the
encapsulation we have is pretty fake in some places (eg., the interface
between libsemanage and libsepol) and doesn't help in most others. The
shared interfaces for everything in libsepol will be _huge_, the ones we
wrote for policyrep were huge by themselves.
I think libsepol should be the library that knows how to read and write
a policydb, maybe has a security server implementation but otherwise
lets people manipulate the policydb however they wish. It would make the
library much smaller, get rid of the need to statically build and be
much less work in the long run.
I still think we need to wait until the wide sweeping policyrep changes
since they remove all the module junk from policydb but after that (or
perhaps at the same time?) we should just make policydb public and
slowly remove the unneeded encapsulation.
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