netfilter: nf_tables: convert built-in tables/chains to chain types
This patch converts built-in tables/chains to chain types that
allows you to deploy customized table and chain configurations from
userspace.
After this patch, you have to specify the chain type when
creating a new chain:
add chain ip filter output { type filter hook input priority 0; }
^^^^ ------
The existing chain types after this patch are: filter, route and
nat. Note that tables are just containers of chains with no specific
semantics, which is a significant change with regards to iptables.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
diff --git a/net/ipv4/netfilter/nft_chain_nat_ipv4.c b/net/ipv4/netfilter/nft_chain_nat_ipv4.c
new file mode 100644
index 0000000..cd28630
--- /dev/null
+++ b/net/ipv4/netfilter/nft_chain_nat_ipv4.c
@@ -0,0 +1,353 @@
+/*
+ * Copyright (c) 2008-2009 Patrick McHardy <kaber@trash.net>
+ * Copyright (c) 2012 Pablo Neira Ayuso <pablo@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
+ * published by the Free Software Foundation.
+ *
+ * Development of this code funded by Astaro AG (http://www.astaro.com/)
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/list.h>
+#include <linux/skbuff.h>
+#include <linux/ip.h>
+#include <linux/netlink.h>
+#include <linux/netfilter.h>
+#include <linux/netfilter_ipv4.h>
+#include <linux/netfilter/nfnetlink.h>
+#include <linux/netfilter/nf_tables.h>
+#include <net/netfilter/nf_conntrack.h>
+#include <net/netfilter/nf_nat.h>
+#include <net/netfilter/nf_nat_core.h>
+#include <net/netfilter/nf_tables.h>
+#include <net/netfilter/nf_nat_l3proto.h>
+#include <net/ip.h>
+
+struct nft_nat {
+ enum nft_registers sreg_addr_min:8;
+ enum nft_registers sreg_addr_max:8;
+ enum nft_registers sreg_proto_min:8;
+ enum nft_registers sreg_proto_max:8;
+ enum nf_nat_manip_type type;
+};
+
+static void nft_nat_eval(const struct nft_expr *expr,
+ struct nft_data data[NFT_REG_MAX + 1],
+ const struct nft_pktinfo *pkt)
+{
+ const struct nft_nat *priv = nft_expr_priv(expr);
+ enum ip_conntrack_info ctinfo;
+ struct nf_conn *ct = nf_ct_get(pkt->skb, &ctinfo);
+ struct nf_nat_range range;
+
+ memset(&range, 0, sizeof(range));
+ if (priv->sreg_addr_min) {
+ range.min_addr.ip = data[priv->sreg_addr_min].data[0];
+ range.max_addr.ip = data[priv->sreg_addr_max].data[0];
+ range.flags |= NF_NAT_RANGE_MAP_IPS;
+ }
+
+ if (priv->sreg_proto_min) {
+ range.min_proto.all = data[priv->sreg_proto_min].data[0];
+ range.max_proto.all = data[priv->sreg_proto_max].data[0];
+ range.flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
+ }
+
+ data[NFT_REG_VERDICT].verdict =
+ nf_nat_setup_info(ct, &range, priv->type);
+}
+
+static const struct nla_policy nft_nat_policy[NFTA_NAT_MAX + 1] = {
+ [NFTA_NAT_ADDR_MIN] = { .type = NLA_U32 },
+ [NFTA_NAT_ADDR_MAX] = { .type = NLA_U32 },
+ [NFTA_NAT_PROTO_MIN] = { .type = NLA_U32 },
+ [NFTA_NAT_PROTO_MAX] = { .type = NLA_U32 },
+ [NFTA_NAT_TYPE] = { .type = NLA_U32 },
+};
+
+static int nft_nat_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
+ const struct nlattr * const tb[])
+{
+ struct nft_nat *priv = nft_expr_priv(expr);
+ int err;
+
+ if (tb[NFTA_NAT_TYPE] == NULL)
+ return -EINVAL;
+
+ switch (ntohl(nla_get_be32(tb[NFTA_NAT_TYPE]))) {
+ case NFT_NAT_SNAT:
+ priv->type = NF_NAT_MANIP_SRC;
+ break;
+ case NFT_NAT_DNAT:
+ priv->type = NF_NAT_MANIP_DST;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ if (tb[NFTA_NAT_ADDR_MIN]) {
+ priv->sreg_addr_min = ntohl(nla_get_be32(tb[NFTA_NAT_ADDR_MIN]));
+ err = nft_validate_input_register(priv->sreg_addr_min);
+ if (err < 0)
+ return err;
+ }
+
+ if (tb[NFTA_NAT_ADDR_MAX]) {
+ priv->sreg_addr_max = ntohl(nla_get_be32(tb[NFTA_NAT_ADDR_MAX]));
+ err = nft_validate_input_register(priv->sreg_addr_max);
+ if (err < 0)
+ return err;
+ } else
+ priv->sreg_addr_max = priv->sreg_addr_min;
+
+ if (tb[NFTA_NAT_PROTO_MIN]) {
+ priv->sreg_proto_min = ntohl(nla_get_be32(tb[NFTA_NAT_PROTO_MIN]));
+ err = nft_validate_input_register(priv->sreg_proto_min);
+ if (err < 0)
+ return err;
+ }
+
+ if (tb[NFTA_NAT_PROTO_MAX]) {
+ priv->sreg_proto_max = ntohl(nla_get_be32(tb[NFTA_NAT_PROTO_MAX]));
+ err = nft_validate_input_register(priv->sreg_proto_max);
+ if (err < 0)
+ return err;
+ } else
+ priv->sreg_proto_max = priv->sreg_proto_min;
+
+ return 0;
+}
+
+static int nft_nat_dump(struct sk_buff *skb, const struct nft_expr *expr)
+{
+ const struct nft_nat *priv = nft_expr_priv(expr);
+
+ switch (priv->type) {
+ case NF_NAT_MANIP_SRC:
+ if (nla_put_be32(skb, NFTA_NAT_TYPE, htonl(NFT_NAT_SNAT)))
+ goto nla_put_failure;
+ break;
+ case NF_NAT_MANIP_DST:
+ if (nla_put_be32(skb, NFTA_NAT_TYPE, htonl(NFT_NAT_DNAT)))
+ goto nla_put_failure;
+ break;
+ }
+
+ if (nla_put_be32(skb, NFTA_NAT_ADDR_MIN, htonl(priv->sreg_addr_min)))
+ goto nla_put_failure;
+ if (nla_put_be32(skb, NFTA_NAT_ADDR_MAX, htonl(priv->sreg_addr_max)))
+ goto nla_put_failure;
+ if (nla_put_be32(skb, NFTA_NAT_PROTO_MIN, htonl(priv->sreg_proto_min)))
+ goto nla_put_failure;
+ if (nla_put_be32(skb, NFTA_NAT_PROTO_MAX, htonl(priv->sreg_proto_max)))
+ goto nla_put_failure;
+ return 0;
+
+nla_put_failure:
+ return -1;
+}
+
+static struct nft_expr_type nft_nat_type;
+static const struct nft_expr_ops nft_nat_ops = {
+ .type = &nft_nat_type,
+ .size = NFT_EXPR_SIZE(sizeof(struct nft_nat)),
+ .eval = nft_nat_eval,
+ .init = nft_nat_init,
+ .dump = nft_nat_dump,
+};
+
+static struct nft_expr_type nft_nat_type __read_mostly = {
+ .name = "nat",
+ .ops = &nft_nat_ops,
+ .policy = nft_nat_policy,
+ .maxattr = NFTA_NAT_MAX,
+ .owner = THIS_MODULE,
+};
+
+/*
+ * NAT chains
+ */
+
+static unsigned int nf_nat_fn(const struct nf_hook_ops *ops,
+ struct sk_buff *skb,
+ const struct net_device *in,
+ const struct net_device *out,
+ int (*okfn)(struct sk_buff *))
+{
+ enum ip_conntrack_info ctinfo;
+ struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
+ struct nf_conn_nat *nat;
+ enum nf_nat_manip_type maniptype = HOOK2MANIP(ops->hooknum);
+ unsigned int ret;
+
+ if (ct == NULL || nf_ct_is_untracked(ct))
+ return NF_ACCEPT;
+
+ NF_CT_ASSERT(!(ip_hdr(skb)->frag_off & htons(IP_MF | IP_OFFSET)));
+
+ nat = nfct_nat(ct);
+ if (nat == NULL) {
+ /* Conntrack module was loaded late, can't add extension. */
+ if (nf_ct_is_confirmed(ct))
+ return NF_ACCEPT;
+ nat = nf_ct_ext_add(ct, NF_CT_EXT_NAT, GFP_ATOMIC);
+ if (nat == NULL)
+ return NF_ACCEPT;
+ }
+
+ switch (ctinfo) {
+ case IP_CT_RELATED:
+ case IP_CT_RELATED + IP_CT_IS_REPLY:
+ if (ip_hdr(skb)->protocol == IPPROTO_ICMP) {
+ if (!nf_nat_icmp_reply_translation(skb, ct, ctinfo,
+ ops->hooknum))
+ return NF_DROP;
+ else
+ return NF_ACCEPT;
+ }
+ /* Fall through */
+ case IP_CT_NEW:
+ if (nf_nat_initialized(ct, maniptype))
+ break;
+
+ ret = nft_do_chain(ops, skb, in, out, okfn);
+ if (ret != NF_ACCEPT)
+ return ret;
+ if (!nf_nat_initialized(ct, maniptype)) {
+ ret = nf_nat_alloc_null_binding(ct, ops->hooknum);
+ if (ret != NF_ACCEPT)
+ return ret;
+ }
+ default:
+ break;
+ }
+
+ return nf_nat_packet(ct, ctinfo, ops->hooknum, skb);
+}
+
+static unsigned int nf_nat_prerouting(const struct nf_hook_ops *ops,
+ struct sk_buff *skb,
+ const struct net_device *in,
+ const struct net_device *out,
+ int (*okfn)(struct sk_buff *))
+{
+ __be32 daddr = ip_hdr(skb)->daddr;
+ unsigned int ret;
+
+ ret = nf_nat_fn(ops, skb, in, out, okfn);
+ if (ret != NF_DROP && ret != NF_STOLEN &&
+ ip_hdr(skb)->daddr != daddr) {
+ skb_dst_drop(skb);
+ }
+ return ret;
+}
+
+static unsigned int nf_nat_postrouting(const struct nf_hook_ops *ops,
+ struct sk_buff *skb,
+ const struct net_device *in,
+ const struct net_device *out,
+ int (*okfn)(struct sk_buff *))
+{
+ enum ip_conntrack_info ctinfo __maybe_unused;
+ const struct nf_conn *ct __maybe_unused;
+ unsigned int ret;
+
+ ret = nf_nat_fn(ops, skb, in, out, okfn);
+#ifdef CONFIG_XFRM
+ if (ret != NF_DROP && ret != NF_STOLEN &&
+ (ct = nf_ct_get(skb, &ctinfo)) != NULL) {
+ enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
+
+ if (ct->tuplehash[dir].tuple.src.u3.ip !=
+ ct->tuplehash[!dir].tuple.dst.u3.ip ||
+ ct->tuplehash[dir].tuple.src.u.all !=
+ ct->tuplehash[!dir].tuple.dst.u.all)
+ return nf_xfrm_me_harder(skb, AF_INET) == 0 ?
+ ret : NF_DROP;
+ }
+#endif
+ return ret;
+}
+
+static unsigned int nf_nat_output(const struct nf_hook_ops *ops,
+ struct sk_buff *skb,
+ const struct net_device *in,
+ const struct net_device *out,
+ int (*okfn)(struct sk_buff *))
+{
+ enum ip_conntrack_info ctinfo;
+ const struct nf_conn *ct;
+ unsigned int ret;
+
+ ret = nf_nat_fn(ops, skb, in, out, okfn);
+ if (ret != NF_DROP && ret != NF_STOLEN &&
+ (ct = nf_ct_get(skb, &ctinfo)) != NULL) {
+ enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
+
+ if (ct->tuplehash[dir].tuple.dst.u3.ip !=
+ ct->tuplehash[!dir].tuple.src.u3.ip) {
+ if (ip_route_me_harder(skb, RTN_UNSPEC))
+ ret = NF_DROP;
+ }
+#ifdef CONFIG_XFRM
+ else if (ct->tuplehash[dir].tuple.dst.u.all !=
+ ct->tuplehash[!dir].tuple.src.u.all)
+ if (nf_xfrm_me_harder(skb, AF_INET))
+ ret = NF_DROP;
+#endif
+ }
+ return ret;
+}
+
+struct nf_chain_type nft_chain_nat_ipv4 = {
+ .family = NFPROTO_IPV4,
+ .name = "nat",
+ .type = NFT_CHAIN_T_NAT,
+ .hook_mask = (1 << NF_INET_PRE_ROUTING) |
+ (1 << NF_INET_POST_ROUTING) |
+ (1 << NF_INET_LOCAL_OUT) |
+ (1 << NF_INET_LOCAL_IN),
+ .fn = {
+ [NF_INET_PRE_ROUTING] = nf_nat_prerouting,
+ [NF_INET_POST_ROUTING] = nf_nat_postrouting,
+ [NF_INET_LOCAL_OUT] = nf_nat_output,
+ [NF_INET_LOCAL_IN] = nf_nat_fn,
+ },
+ .me = THIS_MODULE,
+};
+
+static int __init nft_chain_nat_init(void)
+{
+ int err;
+
+ err = nft_register_chain_type(&nft_chain_nat_ipv4);
+ if (err < 0)
+ return err;
+
+ err = nft_register_expr(&nft_nat_type);
+ if (err < 0)
+ goto err;
+
+ return 0;
+
+err:
+ nft_unregister_chain_type(&nft_chain_nat_ipv4);
+ return err;
+}
+
+static void __exit nft_chain_nat_exit(void)
+{
+ nft_unregister_expr(&nft_nat_type);
+ nft_unregister_chain_type(&nft_chain_nat_ipv4);
+}
+
+module_init(nft_chain_nat_init);
+module_exit(nft_chain_nat_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
+MODULE_ALIAS_NFT_CHAIN(AF_INET, "nat");
+MODULE_ALIAS_NFT_EXPR("nat");