1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * xfrm6_output.c - Common IPsec encapsulation code for IPv6.
4 * Copyright (C) 2002 USAGI/WIDE Project
5 * Copyright (c) 2004 Herbert Xu <herbert@gondor.apana.org.au>
6 */
7
8 #include <linux/if_ether.h>
9 #include <linux/kernel.h>
10 #include <linux/module.h>
11 #include <linux/skbuff.h>
12 #include <linux/icmpv6.h>
13 #include <linux/netfilter_ipv6.h>
14 #include <net/dst.h>
15 #include <net/ipv6.h>
16 #include <net/ip6_route.h>
17 #include <net/xfrm.h>
18
19 int xfrm6_find_1stfragopt(struct xfrm_state *x, struct sk_buff *skb,
20 u8 **prevhdr)
21 {
22 return ip6_find_1stfragopt(skb, prevhdr);
23 }
24 EXPORT_SYMBOL(xfrm6_find_1stfragopt);
25
26 static int xfrm6_local_dontfrag(struct sk_buff *skb)
27 {
28 int proto;
29 struct sock *sk = skb->sk;
30
31 if (sk) {
32 if (sk->sk_family != AF_INET6)
33 return 0;
34
35 proto = sk->sk_protocol;
36 if (proto == IPPROTO_UDP || proto == IPPROTO_RAW)
37 return inet6_sk(sk)->dontfrag;
38 }
39
40 return 0;
41 }
42
43 static void xfrm6_local_rxpmtu(struct sk_buff *skb, u32 mtu)
44 {
45 struct flowi6 fl6;
46 struct sock *sk = skb->sk;
47
48 fl6.flowi6_oif = sk->sk_bound_dev_if;
49 fl6.daddr = ipv6_hdr(skb)->daddr;
50
51 ipv6_local_rxpmtu(sk, &fl6, mtu);
52 }
53
54 void xfrm6_local_error(struct sk_buff *skb, u32 mtu)
55 {
56 struct flowi6 fl6;
57 const struct ipv6hdr *hdr;
58 struct sock *sk = skb->sk;
59
60 hdr = skb->encapsulation ? inner_ipv6_hdr(skb) : ipv6_hdr(skb);
61 fl6.fl6_dport = inet_sk(sk)->inet_dport;
62 fl6.daddr = hdr->daddr;
63
64 ipv6_local_error(sk, EMSGSIZE, &fl6, mtu);
65 }
66
67 static int xfrm6_tunnel_check_size(struct sk_buff *skb)
68 {
69 int mtu, ret = 0;
70 struct dst_entry *dst = skb_dst(skb);
71
72 if (skb->ignore_df)
73 goto out;
74
75 mtu = dst_mtu(dst);
76 if (mtu < IPV6_MIN_MTU)
77 mtu = IPV6_MIN_MTU;
78
79 if ((!skb_is_gso(skb) && skb->len > mtu) ||
80 (skb_is_gso(skb) &&
81 !skb_gso_validate_network_len(skb, ip6_skb_dst_mtu(skb)))) {
82 skb->dev = dst->dev;
83 skb->protocol = htons(ETH_P_IPV6);
84
85 if (xfrm6_local_dontfrag(skb))
86 xfrm6_local_rxpmtu(skb, mtu);
87 else if (skb->sk)
88 xfrm_local_error(skb, mtu);
89 else
90 icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
91 ret = -EMSGSIZE;
92 }
93 out:
94 return ret;
95 }
96
97 int xfrm6_extract_output(struct xfrm_state *x, struct sk_buff *skb)
98 {
99 int err;
100
101 err = xfrm6_tunnel_check_size(skb);
102 if (err)
103 return err;
104
105 XFRM_MODE_SKB_CB(skb)->protocol = ipv6_hdr(skb)->nexthdr;
106
107 return xfrm6_extract_header(skb);
108 }
109
110 int xfrm6_output_finish(struct sock *sk, struct sk_buff *skb)
111 {
112 memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
113
114 #ifdef CONFIG_NETFILTER
115 IP6CB(skb)->flags |= IP6SKB_XFRM_TRANSFORMED;
116 #endif
117
118 return xfrm_output(sk, skb);
119 }
120
121 static int __xfrm6_output_state_finish(struct xfrm_state *x, struct sock *sk,
122 struct sk_buff *skb)
123 {
124 const struct xfrm_state_afinfo *afinfo;
125 int ret = -EAFNOSUPPORT;
126
127 rcu_read_lock();
128 afinfo = xfrm_state_afinfo_get_rcu(x->outer_mode.family);
129 if (likely(afinfo))
130 ret = afinfo->output_finish(sk, skb);
131 else
132 kfree_skb(skb);
133 rcu_read_unlock();
134
135 return ret;
136 }
137
138 static int __xfrm6_output_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
139 {
140 struct xfrm_state *x = skb_dst(skb)->xfrm;
141
142 return __xfrm6_output_state_finish(x, sk, skb);
143 }
144
145 static int __xfrm6_output(struct net *net, struct sock *sk, struct sk_buff *skb)
146 {
147 struct dst_entry *dst = skb_dst(skb);
148 struct xfrm_state *x = dst->xfrm;
149 int mtu;
150 bool toobig;
151
152 #ifdef CONFIG_NETFILTER
153 if (!x) {
154 IP6CB(skb)->flags |= IP6SKB_REROUTED;
155 return dst_output(net, sk, skb);
156 }
157 #endif
158
159 if (x->props.mode != XFRM_MODE_TUNNEL)
160 goto skip_frag;
161
162 if (skb->protocol == htons(ETH_P_IPV6))
163 mtu = ip6_skb_dst_mtu(skb);
164 else
165 mtu = dst_mtu(skb_dst(skb));
166
167 toobig = skb->len > mtu && !skb_is_gso(skb);
168
169 if (toobig && xfrm6_local_dontfrag(skb)) {
170 xfrm6_local_rxpmtu(skb, mtu);
171 kfree_skb(skb);
172 return -EMSGSIZE;
173 } else if (!skb->ignore_df && toobig && skb->sk) {
174 xfrm_local_error(skb, mtu);
175 kfree_skb(skb);
176 return -EMSGSIZE;
177 }
178
179 if (toobig || dst_allfrag(skb_dst(skb)))
180 return ip6_fragment(net, sk, skb,
181 __xfrm6_output_finish);
182
183 skip_frag:
184 return __xfrm6_output_state_finish(x, sk, skb);
185 }
186
187 int xfrm6_output(struct net *net, struct sock *sk, struct sk_buff *skb)
188 {
189 return NF_HOOK_COND(NFPROTO_IPV6, NF_INET_POST_ROUTING,
190 net, sk, skb, NULL, skb_dst(skb)->dev,
191 __xfrm6_output,
192 !(IP6CB(skb)->flags & IP6SKB_REROUTED));
193 }
194
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