[PATCH 06/12] netfilter: nft_ct: add notrack support

[Pablo Neira Ayuso]

This patch adds notrack support.

I decided to add a new expression, given that this doesn't fit into the
existing set operation. Notrack doesn't need a source register, and an
hypothetical NFT_CT_NOTRACK key makes no sense since matching the
untracked state is done through NFT_CT_STATE.

I'm placing this new notrack expression into nft_ct.c, I think a single
module is too much.

Signed-off-by: Pablo Neira Ayuso <pa...@netfilter.org>
---
 net/netfilter/nft_ct.c | 50 +++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 49 insertions(+), 1 deletion(-)

diff --git a/net/netfilter/nft_ct.c b/net/netfilter/nft_ct.c
index d7b0d171172a..6837348c8993 100644
--- a/net/netfilter/nft_ct.c
+++ b/net/netfilter/nft_ct.c
@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2008-2009 Patrick McHardy <ka...@trash.net>
+ * Copyright (c) 2016 Pablo Neira Ayuso <pa...@netfilter.org>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
@@ -518,15 +519,61 @@ static struct nft_expr_type nft_ct_type __read_mostly = {
        .owner          = THIS_MODULE,
 };
 
+static void nft_notrack_eval(const struct nft_expr *expr,
+                            struct nft_regs *regs,
+                            const struct nft_pktinfo *pkt)
+{
+       struct sk_buff *skb = pkt->skb;
+       enum ip_conntrack_info ctinfo;
+       struct nf_conn *ct;
+
+       ct = nf_ct_get(pkt->skb, &ctinfo);
+       /* Previously seen (loopback or untracked)?  Ignore. */
+       if (ct)
+               return;
+
+       ct = nf_ct_untracked_get();
+       atomic_inc(&ct->ct_general.use);
+       skb->nfct = &ct->ct_general;
+       skb->nfctinfo = IP_CT_NEW;
+}
+
+static struct nft_expr_type nft_notrack_type;
+static const struct nft_expr_ops nft_notrack_ops = {
+       .type           = &nft_notrack_type,
+       .size           = NFT_EXPR_SIZE(0),
+       .eval           = nft_notrack_eval,
+};
+
+static struct nft_expr_type nft_notrack_type __read_mostly = {
+       .name           = "notrack",
+       .ops            = &nft_notrack_ops,
+       .owner          = THIS_MODULE,
+};
+
 static int __init nft_ct_module_init(void)
 {
+       int err;
+
        BUILD_BUG_ON(NF_CT_LABELS_MAX_SIZE > NFT_REG_SIZE);
 
-       return nft_register_expr(&nft_ct_type);
+       err = nft_register_expr(&nft_ct_type);
+       if (err < 0)
+               return err;
+
+       err = nft_register_expr(&nft_notrack_type);
+       if (err < 0)
+               goto err1;
+
+       return 0;
+err1:
+       nft_unregister_expr(&nft_ct_type);
+       return err;
 }
 
 static void __exit nft_ct_module_exit(void)
 {
+       nft_unregister_expr(&nft_notrack_type);
        nft_unregister_expr(&nft_ct_type);
 }
 
@@ -536,3 +583,4 @@ module_exit(nft_ct_module_exit);
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Patrick McHardy <ka...@trash.net>");
 MODULE_ALIAS_NFT_EXPR("ct");
+MODULE_ALIAS_NFT_EXPR("notrack");
-- 
2.1.4