path: root/net/sched/act_connmark.c
diff options
authorDaniel Borkmann <daniel@iogearbox.net>2015-08-14 16:03:39 +0200
committerPablo Neira Ayuso <pablo@netfilter.org>2015-08-18 01:22:50 +0200
commitdeedb59039f111c41aa5a54ee384c8e7c08bc78a (patch)
tree7817f65cdb2de30d397e4c980550fe45d3564ed7 /net/sched/act_connmark.c
parentnetfilter: nf_conntrack: push zone object into functions (diff)
netfilter: nf_conntrack: add direction support for zones
This work adds a direction parameter to netfilter zones, so identity separation can be performed only in original/reply or both directions (default). This basically opens up the possibility of doing NAT with conflicting IP address/port tuples from multiple, isolated tenants on a host (e.g. from a netns) without requiring each tenant to NAT twice resp. to use its own dedicated IP address to SNAT to, meaning overlapping tuples can be made unique with the zone identifier in original direction, where the NAT engine will then allocate a unique tuple in the commonly shared default zone for the reply direction. In some restricted, local DNAT cases, also port redirection could be used for making the reply traffic unique w/o requiring SNAT. The consensus we've reached and discussed at NFWS and since the initial implementation [1] was to directly integrate the direction meta data into the existing zones infrastructure, as opposed to the ct->mark approach we proposed initially. As we pass the nf_conntrack_zone object directly around, we don't have to touch all call-sites, but only those, that contain equality checks of zones. Thus, based on the current direction (original or reply), we either return the actual id, or the default NF_CT_DEFAULT_ZONE_ID. CT expectations are direction-agnostic entities when expectations are being compared among themselves, so we can only use the identifier in this case. Note that zone identifiers can not be included into the hash mix anymore as they don't contain a "stable" value that would be equal for both directions at all times, f.e. if only zone->id would unconditionally be xor'ed into the table slot hash, then replies won't find the corresponding conntracking entry anymore. If no particular direction is specified when configuring zones, the behaviour is exactly as we expect currently (both directions). Support has been added for the CT netlink interface as well as the x_tables raw CT target, which both already offer existing interfaces to user space for the configuration of zones. Below a minimal, simplified collision example (script in [2]) with netperf sessions: +--- tenant-1 ---+ mark := 1 | netperf |--+ +----------------+ | CT zone := mark [ORIGINAL] [ip,sport] := X +--------------+ +--- gateway ---+ | mark routing |--| SNAT |-- ... + +--------------+ +---------------+ | +--- tenant-2 ---+ | ~~~|~~~ | netperf |--+ +-----------+ | +----------------+ mark := 2 | netserver |------ ... + [ip,sport] := X +-----------+ [ip,port] := Y On the gateway netns, example: iptables -t raw -A PREROUTING -j CT --zone mark --zone-dir ORIGINAL iptables -t nat -A POSTROUTING -o <dev> -j SNAT --to-source <ip> --random-fully iptables -t mangle -A PREROUTING -m conntrack --ctdir ORIGINAL -j CONNMARK --save-mark iptables -t mangle -A POSTROUTING -m conntrack --ctdir REPLY -j CONNMARK --restore-mark conntrack dump from gateway netns: netperf -H -t TCP_STREAM -l60 -p12865,5555 from each tenant netns tcp 6 431995 ESTABLISHED src= dst= sport=5555 dport=12865 zone-orig=1 src= dst= sport=12865 dport=1024 [ASSURED] mark=1 secctx=system_u:object_r:unlabeled_t:s0 use=1 tcp 6 431994 ESTABLISHED src= dst= sport=5555 dport=12865 zone-orig=2 src= dst= sport=12865 dport=5555 [ASSURED] mark=2 secctx=system_u:object_r:unlabeled_t:s0 use=1 tcp 6 299 ESTABLISHED src= dst= sport=39438 dport=33768 zone-orig=1 src= dst= sport=33768 dport=39438 [ASSURED] mark=1 secctx=system_u:object_r:unlabeled_t:s0 use=1 tcp 6 300 ESTABLISHED src= dst= sport=32889 dport=40206 zone-orig=2 src= dst= sport=40206 dport=32889 [ASSURED] mark=2 secctx=system_u:object_r:unlabeled_t:s0 use=2 Taking this further, test script in [2] creates 200 tenants and runs original-tuple colliding netperf sessions each. A conntrack -L dump in the gateway netns also confirms 200 overlapping entries, all in ESTABLISHED state as expected. I also did run various other tests with some permutations of the script, to mention some: SNAT in random/random-fully/persistent mode, no zones (no overlaps), static zones (original, reply, both directions), etc. [1] http://thread.gmane.org/gmane.comp.security.firewalls.netfilter.devel/57412/ [2] https://paste.fedoraproject.org/242835/65657871/ Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net/sched/act_connmark.c')
1 files changed, 1 insertions, 0 deletions
diff --git a/net/sched/act_connmark.c b/net/sched/act_connmark.c
index e67a1bdd0929..5019a47b9270 100644
--- a/net/sched/act_connmark.c
+++ b/net/sched/act_connmark.c
@@ -72,6 +72,7 @@ static int tcf_connmark(struct sk_buff *skb, const struct tc_action *a,
goto out;
zone.id = ca->zone;
+ zone.dir = NF_CT_DEFAULT_ZONE_DIR;
thash = nf_conntrack_find_get(dev_net(skb->dev), &zone, &tuple);
if (!thash)