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5
6#include <linux/skbuff.h>
7#include <net/xfrm.h>
8#include <net/ip.h>
9#include <net/icmp.h>
10#include <net/inet_ecn.h>
11
12int xfrm4_tunnel_check_size(struct sk_buff *skb)
13{
14 int mtu, ret = 0;
15 struct dst_entry *dst;
16 struct iphdr *iph = skb->nh.iph;
17
18 if (IPCB(skb)->flags & IPSKB_XFRM_TUNNEL_SIZE)
19 goto out;
20
21 IPCB(skb)->flags |= IPSKB_XFRM_TUNNEL_SIZE;
22
23 if (!(iph->frag_off & htons(IP_DF)))
24 goto out;
25
26 dst = skb->dst;
27 mtu = dst_pmtu(dst) - dst->header_len - dst->trailer_len;
28 if (skb->len > mtu) {
29 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu));
30 ret = -EMSGSIZE;
31 }
32out:
33 return ret;
34}
35
36static int ipip_output(struct sk_buff *skb)
37{
38 struct dst_entry *dst = skb->dst;
39 struct xfrm_state *x = dst->xfrm;
40 struct iphdr *iph, *top_iph;
41 int tos, err;
42
43 if ((err = xfrm4_tunnel_check_size(skb)) != 0)
44 goto error_nolock;
45
46 iph = skb->nh.iph;
47
48 spin_lock_bh(&x->lock);
49
50 tos = iph->tos;
51
52 top_iph = (struct iphdr *) skb_push(skb, x->props.header_len);
53 top_iph->ihl = 5;
54 top_iph->version = 4;
55 top_iph->tos = INET_ECN_encapsulate(tos, iph->tos);
56 top_iph->tot_len = htons(skb->len);
57 top_iph->frag_off = iph->frag_off & ~htons(IP_MF|IP_OFFSET);
58 if (!(iph->frag_off & htons(IP_DF)))
59 __ip_select_ident(top_iph, dst, 0);
60 top_iph->ttl = iph->ttl;
61 top_iph->protocol = IPPROTO_IPIP;
62 top_iph->check = 0;
63 top_iph->saddr = x->props.saddr.a4;
64 top_iph->daddr = x->id.daddr.a4;
65 memset(&(IPCB(skb)->opt), 0, sizeof(struct ip_options));
66 ip_send_check(top_iph);
67
68 skb->nh.raw = skb->data;
69 x->curlft.bytes += skb->len;
70 x->curlft.packets++;
71
72 spin_unlock_bh(&x->lock);
73
74 if ((skb->dst = dst_pop(dst)) == NULL) {
75 kfree_skb(skb);
76 err = -EHOSTUNREACH;
77 goto error_nolock;
78 }
79 return NET_XMIT_BYPASS;
80
81error_nolock:
82 kfree_skb(skb);
83 return err;
84}
85
86static int ipip_xfrm_rcv(struct xfrm_state *x, struct xfrm_decap_state *decap, struct sk_buff *skb)
87{
88 return 0;
89}
90
91static struct xfrm_tunnel *ipip_handler;
92static DECLARE_MUTEX(xfrm4_tunnel_sem);
93
94int xfrm4_tunnel_register(struct xfrm_tunnel *handler)
95{
96 int ret;
97
98 down(&xfrm4_tunnel_sem);
99 ret = 0;
100 if (ipip_handler != NULL)
101 ret = -EINVAL;
102 if (!ret)
103 ipip_handler = handler;
104 up(&xfrm4_tunnel_sem);
105
106 return ret;
107}
108
109int xfrm4_tunnel_deregister(struct xfrm_tunnel *handler)
110{
111 int ret;
112
113 down(&xfrm4_tunnel_sem);
114 ret = 0;
115 if (ipip_handler != handler)
116 ret = -EINVAL;
117 if (!ret)
118 ipip_handler = NULL;
119 up(&xfrm4_tunnel_sem);
120
121 synchronize_net();
122
123 return ret;
124}
125
126static int ipip_rcv(struct sk_buff *skb)
127{
128 struct xfrm_tunnel *handler = ipip_handler;
129
130
131 if (handler && handler->handler(skb) == 0)
132 return 0;
133
134 return xfrm4_rcv_encap(skb, 0);
135}
136
137static void ipip_err(struct sk_buff *skb, u32 info)
138{
139 struct xfrm_tunnel *handler = ipip_handler;
140 u32 arg = info;
141
142 if (handler)
143 handler->err_handler(skb, &arg);
144}
145
146static int ipip_init_state(struct xfrm_state *x, void *args)
147{
148 if (!x->props.mode)
149 return -EINVAL;
150 x->props.header_len = sizeof(struct iphdr);
151
152 return 0;
153}
154
155static void ipip_destroy(struct xfrm_state *x)
156{
157}
158
159static struct xfrm_type ipip_type = {
160 .description = "IPIP",
161 .owner = THIS_MODULE,
162 .proto = IPPROTO_IPIP,
163 .init_state = ipip_init_state,
164 .destructor = ipip_destroy,
165 .input = ipip_xfrm_rcv,
166 .output = ipip_output
167};
168
169static struct inet_protocol ipip_protocol = {
170 .handler = ipip_rcv,
171 .err_handler = ipip_err,
172 .no_policy = 1,
173};
174
175static int __init ipip_init(void)
176{
177 if (xfrm_register_type(&ipip_type, AF_INET) < 0) {
178 printk(KERN_INFO "ipip init: can't add xfrm type\n");
179 return -EAGAIN;
180 }
181 if (inet_add_protocol(&ipip_protocol, IPPROTO_IPIP) < 0) {
182 printk(KERN_INFO "ipip init: can't add protocol\n");
183 xfrm_unregister_type(&ipip_type, AF_INET);
184 return -EAGAIN;
185 }
186 return 0;
187}
188
189static void __exit ipip_fini(void)
190{
191 if (inet_del_protocol(&ipip_protocol, IPPROTO_IPIP) < 0)
192 printk(KERN_INFO "ipip close: can't remove protocol\n");
193 if (xfrm_unregister_type(&ipip_type, AF_INET) < 0)
194 printk(KERN_INFO "ipip close: can't remove xfrm type\n");
195}
196
197module_init(ipip_init);
198module_exit(ipip_fini);
199MODULE_LICENSE("GPL");
200
