src: add nat support for the inet family

consider a simple ip6 nat table:

table ip6 nat { chain output {
  type nat hook output priority 0; policy accept;
  dnat to dead:2::99
}

Now consider same ruleset, but using 'table inet nat':
nft now lacks context to determine address family to parse 'to $address'.

This adds code to make the following work:

table inet nat { [ .. ]
  # detect af from network protocol context:
  ip6 daddr dead::2::1 dnat to dead:2::99

  # use new dnat ip6 keyword:
  dnat ip6 to dead:2::99
  }

On list side, the keyword is only shown in the inet family, else the
short version (dnat to ...) is used as the family is redundant when the
table already mandates the ip protocol version supported.

Address mismatches such as

table ip6 { ..
	dnat ip to 1.2.3.4

are detected/handled during the evaluation phase.

Signed-off-by: Florian Westphal <fw@strlen.de>
Acked-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 54 insertions, 0 deletions

diff --git a/tests/py/inet/dnat.t.payload b/tests/py/inet/dnat.t.payload
new file mode 100644
index 00000000..b81caf7b
--- /dev/null
+++ b/tests/py/inet/dnat.t.payload
@@ -0,0 +1,54 @@
+# iifname "foo" tcp dport 80 redirect to :8080
+inet test-inet prerouting
+  [ meta load iifname => reg 1 ]
+  [ cmp eq reg 1 0x006f6f66 0x00000000 0x00000000 0x00000000 ]
+  [ meta load l4proto => reg 1 ]
+  [ cmp eq reg 1 0x00000006 ]
+  [ payload load 2b @ transport header + 2 => reg 1 ]
+  [ cmp eq reg 1 0x00005000 ]
+  [ immediate reg 1 0x0000901f ]
+  [ redir proto_min reg 1 ]
+
+# iifname "eth0" tcp dport 443 dnat ip to 192.168.3.2
+inet test-inet prerouting
+  [ meta load iifname => reg 1 ]
+  [ cmp eq reg 1 0x30687465 0x00000000 0x00000000 0x00000000 ]
+  [ meta load l4proto => reg 1 ]
+  [ cmp eq reg 1 0x00000006 ]
+  [ payload load 2b @ transport header + 2 => reg 1 ]
+  [ cmp eq reg 1 0x0000bb01 ]
+  [ immediate reg 1 0x0203a8c0 ]
+  [ nat dnat ip addr_min reg 1 addr_max reg 0 ]
+
+# iifname "eth0" tcp dport 443 dnat ip6 to [dead::beef]:4443
+inet test-inet prerouting
+  [ meta load iifname => reg 1 ]
+  [ cmp eq reg 1 0x30687465 0x00000000 0x00000000 0x00000000 ]
+  [ meta load l4proto => reg 1 ]
+  [ cmp eq reg 1 0x00000006 ]
+  [ payload load 2b @ transport header + 2 => reg 1 ]
+  [ cmp eq reg 1 0x0000bb01 ]
+  [ immediate reg 1 0x0000adde 0x00000000 0x00000000 0xefbe0000 ]
+  [ immediate reg 2 0x00005b11 ]
+  [ nat dnat ip6 addr_min reg 1 addr_max reg 0 proto_min reg 2 proto_max reg 0 ]
+
+# dnat ip to ct mark map { 0x00000014 : 1.2.3.4}
+__map%d test-inet b size 1
+__map%d test-inet 0
+        element 00000014  : 04030201 0 [end]
+inet test-inet prerouting
+  [ ct load mark => reg 1 ]
+  [ lookup reg 1 set __map%d dreg 1 ]
+  [ nat dnat ip addr_min reg 1 addr_max reg 0 ]
+
+# dnat ip to ct mark . ip daddr map { 0x00000014 . 1.1.1.1 : 1.2.3.4}
+__map%d test-inet b size 1
+__map%d test-inet 0
+        element 00000014 01010101  : 04030201 0 [end]
+inet test-inet prerouting
+  [ meta load nfproto => reg 1 ]
+  [ cmp eq reg 1 0x00000002 ]
+  [ ct load mark => reg 1 ]
+  [ payload load 4b @ network header + 16 => reg 9 ]
+  [ lookup reg 1 set __map%d dreg 1 ]
+  [ nat dnat ip addr_min reg 1 addr_max reg 0 ]