Stephen Smalley wrote:
> On Thu, 2006-08-31 at 12:20 -0500, Klaus Weidner wrote:
>>On Thu, Aug 31, 2006 at 08:57:05AM -0400, Paul Moore wrote:
>>>Klaus Weidner wrote:
>>>
>>>>I was a bit surprised that a "s2-s2" process can connect successfully to
>>>>a "s3-s3" process, send it data, and select/poll(2) waiting for data.
>>
>>[...]
>>
>>>>It works as expected the other way around, the s3 process gets an
>>>>immediate "connection refused" when trying to connect to the s2 process.
>>>
>>>This smells like a policy issue to me. Taking a quick look at the
>>>reference policy mls constraints (this is from a svn snapshot which is
>>>probably a month or two old, so it may have changed) I see the following
>>>constraint (unrelated types removed for clarity):
>>
>>It's a bit more complex now:
>>
>># the socket "read" ops (note the check is dominance of the low level)
>>mlsconstrain { socket tcp_socket udp_socket rawip_socket netlink_socket
>>packet_socket key_socket unix_stream_socket unix_dgram_socket
>>netlink_route_socket netlink_firewall_socket netlink_tcpdiag_socket
>>netlink_nflog_socket netlink_xfrm_socket netlink_selinux_socket
>>netlink_audit_socket netlink_ip6fw_socket netlink_dnrt_socket } { read
>>getattr listen accept getopt recvfrom recv_msg }
>> (( l1 dom l2 ) or
>> (( t1 == mlsnetreadtoclr ) and ( h1 dom l2 )) or
>> ( t1 == mlsnetread ));
>>
>># the socket "write" ops
>>mlsconstrain { socket tcp_socket udp_socket rawip_socket netlink_socket
>>packet_socket key_socket unix_stream_socket unix_dgram_socket
>>netlink_route_socket netlink_firewall_socket netlink_tcpdiag_socket
>>netlink_nflog_socket netlink_xfrm_socket netlink_selinux_socket
>>netlink_audit_socket netlink_ip6fw_socket netlink_dnrt_socket } { write
>>setattr relabelfrom connect setopt shutdown }
>> ((( l1 dom l2 ) and ( l1 domby h2 )) or
>> (( t1 == mlsnetwritetoclr ) and ( h1 dom l2 ) and ( l1 domby l2 )) or
>> ( t1 == mlsnetwrite ));
>>
>>Based on that policy, I'd expect the constraint on "connect" to prevent a
>>l1=s2,h1=s2 process from connecting to a l2=s2,h2=s2 port. Am I
>>misunderstanding something or is the check mixed up?
>
> connect is a process-to-socket check handled entirely in the socket
> layer, i.e. can process A initiate a connection via socket S (where S is
> its local endpoint, not the peer). It isn't a check on the peer.
>
> recv_msg is likely the one of interest to you for NetLabel. You could
> separate out the mls constraint on tcp_socket to require equivalence for
> recv_msg in that case (overloading with old net controls is bad though).
I know we've talked about this before and decided to stick with using
recv_msg ... does it make sense to introduce a new permission, say
nlbl_recv? Or do we just not care because of the secid reconciliation work?
> If secid reconciliation progresses fully and secmark is enabled, then
> packet recv would be the check of interest.
--
paul moore
linux security @ hp
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