Jail + sysv shmem

Koen Martens fbsd at metro.cx
Fri Nov 26 11:38:02 PST 2004


Hello Hackers,

For a while i've been wanting shared memory to be usable withing jails,
but with cross-jail protection. Ie. shared memory is restricted to a
jail. 

Recently I've been digging a bit in the freebsd kernel source code
(which is new to me, been doing quite some linux kernel hacking though).
It looks like this is actually not _that_ difficult to implement. 

So, did anyone try this yet? Any pointers?

I think it can be done by putting the jail id in struct ipc_perm (in
sys/ipc.h), and then basically editing sysv_{msg,sem,shm}.c to extend
these checks that are all over there:

        if (!jail_sysvipc_allowed && jailed(td->td_ucred))
                return (ENOSYS);

Does that sound ok?

Kind regards,

Koen

-- 
K.F.J. Martens, Sonologic, http://www.sonologic.nl/
Networking, embedded systems, unix expertise, artificial intelligence.
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