userns: Convert cls_flow to work with user namespaces enabled

The flow classifier can use uids and gids of the sockets that
are transmitting packets and do insert those uids and gids
into the packet classification calcuation.  I don't fully
understand the details but it appears that we can depend
on specific uids and gids when making traffic classification
decisions.

To work with user namespaces enabled map from kuids and kgids
into uids and gids in the initial user namespace giving raw
integer values the code can play with and depend on.

To avoid issues of userspace depending on uids and gids in
packet classifiers installed from other user namespaces
and getting confused deny all packet classifiers that
use uids or gids that are not comming from a netlink socket
in the initial user namespace.

Cc: Patrick McHardy <kaber@trash.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Changli Gao <xiaosuo@gmail.com>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

1 files changed, 0 insertions, 1 deletions

diff --git a/init/Kconfig b/init/Kconfig
index 2660b312ae9d..b44c3a390699 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -943,7 +943,6 @@ config UIDGID_CONVERTED
 
         # Networking
         depends on NET_9P = n
-        depends on NET_CLS_FLOW = n
         depends on NETFILTER_XT_MATCH_OWNER = n
         depends on NETFILTER_XT_MATCH_RECENT = n
         depends on NETFILTER_XT_TARGET_LOG = n