On Fri, Mar 31, 2017 at 09:30:56AM -0400, Stephen Smalley wrote:
> On Fri, 2017-03-31 at 09:25 -0400, Stephen Smalley wrote:
> > On Fri, 2017-03-31 at 14:09 +0200, Dominick Grift wrote:
> > > I vaguely recall that we discussed this issue or at least that i
> > > mentioned it here but i can't recall the outcome if any:
> > > 
> > > So today on my rawhide system i noticed that i somehow forgot to
> > > add
> > > support for the smc_socket class (i suspect that is part of the
> > > extended socket class patches)
> > > 
> > > I added the class (which i suppose is unordered like the othe
> > > extended socket classes) but as soon as I loaded up the policy with
> > > the new unordered smc_socket class the system became unusable.
> > > 
> > > This is because the dbus object manager became confused due to my
> > > adding a new (unordered) class at runtime, and that the dbus class
> > > was no longer working.
> > > 
> > > Modern systems heavily rely on dbus at the heart and so it is
> > > undesire-able that this happens.
> > > 
> > > A reboot clears this issue up but adding (unordered) classes at
> > > runtime should not cause these issues i suspect
> > 
> > dbusd doesn't use selinux_check_access() and therefore does not yet
> > support reordering of their classes/permissions at runtime.  The same
> > is true of all userspace object managers created before
> > selinux_check_access() was introduced - anything that directly calls
> > security_compute_av() or avc_has_perm(). dbusd does call
> > selinux_set_mapping() at startup, so it can correctly handle
> > reordering of classes/permissions across restarts, but not while it
> > is
> > running.  Calling selinux_set_mapping() again upon policy reloads
> > (e.g.
> > from policy_reload_callback() if (event == AVC_CALLBACK_RESET) before
> > returning) may fix this problem, but requires proper locking.  Even
> > better would be to rid the dbusd selinux implementation of threading
> > entirely, see https://bugs.freedesktop.org/show_bug.cgi?id=92831#c4

Thank you, I suppose i should take this to them then.

> > 
> > smc_socket was added by the kernel developers as part of the merge
> > with
> > net-next since we now trigger a build failure in the kernel if any
> > new
> > address families are introduced without adding a corresponding
> > security
> > class (so that SELinux always supports a separate class per network
> > address family going forward). So there have been no policy patches
> > submitted yet to define it in refpolicy even AFAIK.
> > 
> > [1] https://github.com/SELinuxProject/selinux/issues/34

So i suppose its an unordered class? or do i have to order this one to avoid future issues?

> 
> BTW, I'm not sure what you did to trigger the problem.  When I tested
> the extended socket classes, I added them to my running policy via a
> CIL module like this:

Well i just added this commit (ignore the typo in the name) which adds the new class to the unordered socket list

https://github.com/DefenSec/dssp2-base/commit/5e3ada7d12525c8c659f347863f09ec9caeceb56

then i built rpms using this script:

https://github.com/DefenSec/dssp2-standard/blob/master/support/rpm/dssp2-standard.sh

and just rpm -Uvh the new rpm

> 
> (policycap extended_socket_class)
> 
> (classcommon sctp_socket socket)
> (class sctp_socket (node_bind))
> 
> <snip>
> 
> (classcommon qipcrtr_socket socket)
> (class qipcrtr_socket ())
> 
> (classorder (unordered sctp_socket icmp_socket ax25_socket ipx_socket
> netrom_socket bridge_socket atmpvc_socket x25_socket rose_socket
> decnet_socket atmsvc_socket rds_socket irda_socket pppox_socket
> llc_socket ib_socket mpls_socket can_socket tipc_socket
> bluetooth_socket iucv_socket rxrpc_socket isdn_socket phonet_socket
> ieee802154_socket caif_socket alg_socket nfc_socket vsock_socket
> kcm_socket qipcrtr_socket))
> 
> The classorder statement at the end ensured that they were appended to
> the end of the class list and therefore did not break anything.
> 

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Dominick Grift