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6#include <linux/kernel.h>
7#include <linux/netlink.h>
8#include <linux/netfilter.h>
9#include <linux/netfilter/nf_tables.h>
10#include <net/dst.h>
11#include <net/ip6_route.h>
12#include <net/route.h>
13#include <net/netfilter/nf_tables.h>
14#include <net/netfilter/nf_tables_core.h>
15
16struct nft_rt {
17 enum nft_rt_keys key:8;
18 enum nft_registers dreg:8;
19};
20
21static u16 get_tcpmss(const struct nft_pktinfo *pkt, const struct dst_entry *skbdst)
22{
23 u32 minlen = sizeof(struct ipv6hdr), mtu = dst_mtu(skbdst);
24 const struct sk_buff *skb = pkt->skb;
25 struct dst_entry *dst = NULL;
26 struct flowi fl;
27
28 memset(&fl, 0, sizeof(fl));
29
30 switch (nft_pf(pkt)) {
31 case NFPROTO_IPV4:
32 fl.u.ip4.daddr = ip_hdr(skb)->saddr;
33 minlen = sizeof(struct iphdr) + sizeof(struct tcphdr);
34 break;
35 case NFPROTO_IPV6:
36 fl.u.ip6.daddr = ipv6_hdr(skb)->saddr;
37 minlen = sizeof(struct ipv6hdr) + sizeof(struct tcphdr);
38 break;
39 }
40
41 nf_route(nft_net(pkt), &dst, &fl, false, nft_pf(pkt));
42 if (dst) {
43 mtu = min(mtu, dst_mtu(dst));
44 dst_release(dst);
45 }
46
47 if (mtu <= minlen || mtu > 0xffff)
48 return TCP_MSS_DEFAULT;
49
50 return mtu - minlen;
51}
52
53void nft_rt_get_eval(const struct nft_expr *expr,
54 struct nft_regs *regs,
55 const struct nft_pktinfo *pkt)
56{
57 const struct nft_rt *priv = nft_expr_priv(expr);
58 const struct sk_buff *skb = pkt->skb;
59 u32 *dest = ®s->data[priv->dreg];
60 const struct dst_entry *dst;
61
62 dst = skb_dst(skb);
63 if (!dst)
64 goto err;
65
66 switch (priv->key) {
67#ifdef CONFIG_IP_ROUTE_CLASSID
68 case NFT_RT_CLASSID:
69 *dest = dst->tclassid;
70 break;
71#endif
72 case NFT_RT_NEXTHOP4:
73 if (nft_pf(pkt) != NFPROTO_IPV4)
74 goto err;
75
76 *dest = (__force u32)rt_nexthop((const struct rtable *)dst,
77 ip_hdr(skb)->daddr);
78 break;
79 case NFT_RT_NEXTHOP6:
80 if (nft_pf(pkt) != NFPROTO_IPV6)
81 goto err;
82
83 memcpy(dest, rt6_nexthop((struct rt6_info *)dst,
84 &ipv6_hdr(skb)->daddr),
85 sizeof(struct in6_addr));
86 break;
87 case NFT_RT_TCPMSS:
88 nft_reg_store16(dest, get_tcpmss(pkt, dst));
89 break;
90#ifdef CONFIG_XFRM
91 case NFT_RT_XFRM:
92 nft_reg_store8(dest, !!dst->xfrm);
93 break;
94#endif
95 default:
96 WARN_ON(1);
97 goto err;
98 }
99 return;
100
101err:
102 regs->verdict.code = NFT_BREAK;
103}
104
105static 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 },
108};
109
110static int nft_rt_get_init(const struct nft_ctx *ctx,
111 const struct nft_expr *expr,
112 const struct nlattr * const tb[])
113{
114 struct nft_rt *priv = nft_expr_priv(expr);
115 unsigned int len;
116
117 if (tb[NFTA_RT_KEY] == NULL ||
118 tb[NFTA_RT_DREG] == NULL)
119 return -EINVAL;
120
121 priv->key = ntohl(nla_get_be32(tb[NFTA_RT_KEY]));
122 switch (priv->key) {
123#ifdef CONFIG_IP_ROUTE_CLASSID
124 case NFT_RT_CLASSID:
125#endif
126 case NFT_RT_NEXTHOP4:
127 len = sizeof(u32);
128 break;
129 case NFT_RT_NEXTHOP6:
130 len = sizeof(struct in6_addr);
131 break;
132 case NFT_RT_TCPMSS:
133 len = sizeof(u16);
134 break;
135#ifdef CONFIG_XFRM
136 case NFT_RT_XFRM:
137 len = sizeof(u8);
138 break;
139#endif
140 default:
141 return -EOPNOTSUPP;
142 }
143
144 priv->dreg = nft_parse_register(tb[NFTA_RT_DREG]);
145 return nft_validate_register_store(ctx, priv->dreg, NULL,
146 NFT_DATA_VALUE, len);
147}
148
149static int nft_rt_get_dump(struct sk_buff *skb,
150 const struct nft_expr *expr)
151{
152 const struct nft_rt *priv = nft_expr_priv(expr);
153
154 if (nla_put_be32(skb, NFTA_RT_KEY, htonl(priv->key)))
155 goto nla_put_failure;
156 if (nft_dump_register(skb, NFTA_RT_DREG, priv->dreg))
157 goto nla_put_failure;
158 return 0;
159
160nla_put_failure:
161 return -1;
162}
163
164static int nft_rt_validate(const struct nft_ctx *ctx, const struct nft_expr *expr,
165 const struct nft_data **data)
166{
167 const struct nft_rt *priv = nft_expr_priv(expr);
168 unsigned int hooks;
169
170 switch (priv->key) {
171 case NFT_RT_NEXTHOP4:
172 case NFT_RT_NEXTHOP6:
173 case NFT_RT_CLASSID:
174 case NFT_RT_XFRM:
175 return 0;
176 case NFT_RT_TCPMSS:
177 hooks = (1 << NF_INET_FORWARD) |
178 (1 << NF_INET_LOCAL_OUT) |
179 (1 << NF_INET_POST_ROUTING);
180 break;
181 default:
182 return -EINVAL;
183 }
184
185 return nft_chain_validate_hooks(ctx->chain, hooks);
186}
187
188static const struct nft_expr_ops nft_rt_get_ops = {
189 .type = &nft_rt_type,
190 .size = NFT_EXPR_SIZE(sizeof(struct nft_rt)),
191 .eval = nft_rt_get_eval,
192 .init = nft_rt_get_init,
193 .dump = nft_rt_get_dump,
194 .validate = nft_rt_validate,
195};
196
197struct nft_expr_type nft_rt_type __read_mostly = {
198 .name = "rt",
199 .ops = &nft_rt_get_ops,
200 .policy = nft_rt_policy,
201 .maxattr = NFTA_RT_MAX,
202 .owner = THIS_MODULE,
203};
204
