5 * YOSHIFUJI Hideaki @USAGI
6 * Split up af-specific portion
7 * Derek Atkins <derek@ihtfp.com>
8 * Add Encapsulation support
12 #include <linux/slab.h>
13 #include <linux/module.h>
14 #include <linux/string.h>
15 #include <linux/netfilter.h>
16 #include <linux/netfilter_ipv4.h>
20 int xfrm4_extract_input(struct xfrm_state *x, struct sk_buff *skb)
22 return xfrm4_extract_header(skb);
25 static inline int xfrm4_rcv_encap_finish(struct sk_buff *skb)
28 const struct iphdr *iph = ip_hdr(skb);
30 if (ip_route_input_noref(skb, iph->daddr, iph->saddr,
34 return dst_input(skb);
40 int xfrm4_transport_finish(struct sk_buff *skb, int async)
42 struct iphdr *iph = ip_hdr(skb);
44 iph->protocol = XFRM_MODE_SKB_CB(skb)->protocol;
46 #ifndef CONFIG_NETFILTER
48 return -iph->protocol;
51 __skb_push(skb, skb->data - skb_network_header(skb));
52 iph->tot_len = htons(skb->len);
55 NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, skb, skb->dev, NULL,
56 xfrm4_rcv_encap_finish);
60 /* If it's a keepalive packet, then just eat it.
61 * If it's an encapsulated packet, then pass it to the
63 * Returns 0 if skb passed to xfrm or was dropped.
64 * Returns >0 if skb should be passed to UDP.
65 * Returns <0 if skb should be resubmitted (-ret is protocol)
67 int xfrm4_udp_encap_rcv(struct sock *sk, struct sk_buff *skb)
69 struct udp_sock *up = udp_sk(sk);
76 __u16 encap_type = up->encap_type;
78 /* if this is not encapsulated socket, then just return now */
82 /* If this is a paged skb, make sure we pull up
83 * whatever data we need to look at. */
84 len = skb->len - sizeof(struct udphdr);
85 if (!pskb_may_pull(skb, sizeof(struct udphdr) + min(len, 8)))
88 /* Now we can get the pointers */
90 udpdata = (__u8 *)uh + sizeof(struct udphdr);
91 udpdata32 = (__be32 *)udpdata;
95 case UDP_ENCAP_ESPINUDP:
96 /* Check if this is a keepalive packet. If so, eat it. */
97 if (len == 1 && udpdata[0] == 0xff) {
99 } else if (len > sizeof(struct ip_esp_hdr) && udpdata32[0] != 0) {
100 /* ESP Packet without Non-ESP header */
101 len = sizeof(struct udphdr);
103 /* Must be an IKE packet.. pass it through */
106 case UDP_ENCAP_ESPINUDP_NON_IKE:
107 /* Check if this is a keepalive packet. If so, eat it. */
108 if (len == 1 && udpdata[0] == 0xff) {
110 } else if (len > 2 * sizeof(u32) + sizeof(struct ip_esp_hdr) &&
111 udpdata32[0] == 0 && udpdata32[1] == 0) {
113 /* ESP Packet with Non-IKE marker */
114 len = sizeof(struct udphdr) + 2 * sizeof(u32);
116 /* Must be an IKE packet.. pass it through */
121 /* At this point we are sure that this is an ESPinUDP packet,
122 * so we need to remove 'len' bytes from the packet (the UDP
123 * header and optional ESP marker bytes) and then modify the
124 * protocol to ESP, and then call into the transform receiver.
126 if (skb_unclone(skb, GFP_ATOMIC))
129 /* Now we can update and verify the packet length... */
131 iphlen = iph->ihl << 2;
132 iph->tot_len = htons(ntohs(iph->tot_len) - len);
133 if (skb->len < iphlen + len) {
134 /* packet is too small!?! */
138 /* pull the data buffer up to the ESP header and set the
139 * transport header to point to ESP. Keep UDP on the stack
142 __skb_pull(skb, len);
143 skb_reset_transport_header(skb);
146 return xfrm4_rcv_encap(skb, IPPROTO_ESP, 0, encap_type);
153 int xfrm4_rcv(struct sk_buff *skb)
155 return xfrm4_rcv_spi(skb, ip_hdr(skb)->protocol, 0);
157 EXPORT_SYMBOL(xfrm4_rcv);