2 * Copyright (c) 2016 Anders K. Pedersen <akp@cohaesio.com>
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
9 #include <linux/kernel.h>
10 #include <linux/init.h>
11 #include <linux/module.h>
12 #include <linux/netlink.h>
13 #include <linux/netfilter.h>
14 #include <linux/netfilter/nf_tables.h>
16 #include <net/ip6_route.h>
17 #include <net/route.h>
18 #include <net/netfilter/nf_tables.h>
19 #include <net/netfilter/nf_tables_core.h>
22 enum nft_rt_keys key:8;
23 enum nft_registers dreg:8;
26 static u16 get_tcpmss(const struct nft_pktinfo *pkt, const struct dst_entry *skbdst)
28 u32 minlen = sizeof(struct ipv6hdr), mtu = dst_mtu(skbdst);
29 const struct sk_buff *skb = pkt->skb;
30 struct dst_entry *dst = NULL;
33 memset(&fl, 0, sizeof(fl));
35 switch (nft_pf(pkt)) {
37 fl.u.ip4.daddr = ip_hdr(skb)->saddr;
38 minlen = sizeof(struct iphdr) + sizeof(struct tcphdr);
41 fl.u.ip6.daddr = ipv6_hdr(skb)->saddr;
42 minlen = sizeof(struct ipv6hdr) + sizeof(struct tcphdr);
46 nf_route(nft_net(pkt), &dst, &fl, false, nft_pf(pkt));
48 mtu = min(mtu, dst_mtu(dst));
52 if (mtu <= minlen || mtu > 0xffff)
53 return TCP_MSS_DEFAULT;
58 static void nft_rt_get_eval(const struct nft_expr *expr,
59 struct nft_regs *regs,
60 const struct nft_pktinfo *pkt)
62 const struct nft_rt *priv = nft_expr_priv(expr);
63 const struct sk_buff *skb = pkt->skb;
64 u32 *dest = ®s->data[priv->dreg];
65 const struct dst_entry *dst;
72 #ifdef CONFIG_IP_ROUTE_CLASSID
74 *dest = dst->tclassid;
78 if (nft_pf(pkt) != NFPROTO_IPV4)
81 *dest = (__force u32)rt_nexthop((const struct rtable *)dst,
85 if (nft_pf(pkt) != NFPROTO_IPV6)
88 memcpy(dest, rt6_nexthop((struct rt6_info *)dst,
89 &ipv6_hdr(skb)->daddr),
90 sizeof(struct in6_addr));
93 nft_reg_store16(dest, get_tcpmss(pkt, dst));
102 regs->verdict.code = NFT_BREAK;
105 static const struct nla_policy nft_rt_policy[NFTA_RT_MAX + 1] = {
106 [NFTA_RT_DREG] = { .type = NLA_U32 },
107 [NFTA_RT_KEY] = { .type = NLA_U32 },
110 static int nft_rt_get_init(const struct nft_ctx *ctx,
111 const struct nft_expr *expr,
112 const struct nlattr * const tb[])
114 struct nft_rt *priv = nft_expr_priv(expr);
117 if (tb[NFTA_RT_KEY] == NULL ||
118 tb[NFTA_RT_DREG] == NULL)
121 priv->key = ntohl(nla_get_be32(tb[NFTA_RT_KEY]));
123 #ifdef CONFIG_IP_ROUTE_CLASSID
126 case NFT_RT_NEXTHOP4:
129 case NFT_RT_NEXTHOP6:
130 len = sizeof(struct in6_addr);
139 priv->dreg = nft_parse_register(tb[NFTA_RT_DREG]);
140 return nft_validate_register_store(ctx, priv->dreg, NULL,
141 NFT_DATA_VALUE, len);
144 static int nft_rt_get_dump(struct sk_buff *skb,
145 const struct nft_expr *expr)
147 const struct nft_rt *priv = nft_expr_priv(expr);
149 if (nla_put_be32(skb, NFTA_RT_KEY, htonl(priv->key)))
150 goto nla_put_failure;
151 if (nft_dump_register(skb, NFTA_RT_DREG, priv->dreg))
152 goto nla_put_failure;
159 static int nft_rt_validate(const struct nft_ctx *ctx, const struct nft_expr *expr,
160 const struct nft_data **data)
162 const struct nft_rt *priv = nft_expr_priv(expr);
166 case NFT_RT_NEXTHOP4:
167 case NFT_RT_NEXTHOP6:
171 hooks = (1 << NF_INET_FORWARD) |
172 (1 << NF_INET_LOCAL_OUT) |
173 (1 << NF_INET_POST_ROUTING);
179 return nft_chain_validate_hooks(ctx->chain, hooks);
182 static struct nft_expr_type nft_rt_type;
183 static const struct nft_expr_ops nft_rt_get_ops = {
184 .type = &nft_rt_type,
185 .size = NFT_EXPR_SIZE(sizeof(struct nft_rt)),
186 .eval = nft_rt_get_eval,
187 .init = nft_rt_get_init,
188 .dump = nft_rt_get_dump,
189 .validate = nft_rt_validate,
192 static struct nft_expr_type nft_rt_type __read_mostly = {
194 .ops = &nft_rt_get_ops,
195 .policy = nft_rt_policy,
196 .maxattr = NFTA_RT_MAX,
197 .owner = THIS_MODULE,
200 static int __init nft_rt_module_init(void)
202 return nft_register_expr(&nft_rt_type);
205 static void __exit nft_rt_module_exit(void)
207 nft_unregister_expr(&nft_rt_type);
210 module_init(nft_rt_module_init);
211 module_exit(nft_rt_module_exit);
213 MODULE_LICENSE("GPL");
214 MODULE_AUTHOR("Anders K. Pedersen <akp@cohaesio.com>");
215 MODULE_ALIAS_NFT_EXPR("rt");