1 // SPDX-License-Identifier: GPL-2.0
6 * YOSHIFUJI Hideaki @USAGI
7 * Split up af-specific portion
8 * Derek Atkins <derek@ihtfp.com>
9 * Add Encapsulation support
13 #include <linux/slab.h>
14 #include <linux/module.h>
15 #include <linux/string.h>
16 #include <linux/netfilter.h>
17 #include <linux/netfilter_ipv4.h>
21 int xfrm4_extract_input(struct xfrm_state *x, struct sk_buff *skb)
23 return xfrm4_extract_header(skb);
26 static inline int xfrm4_rcv_encap_finish(struct net *net, struct sock *sk,
30 const struct iphdr *iph = ip_hdr(skb);
32 if (ip_route_input_noref(skb, iph->daddr, iph->saddr,
36 return dst_input(skb);
42 int xfrm4_transport_finish(struct sk_buff *skb, int async)
44 struct xfrm_offload *xo = xfrm_offload(skb);
45 struct iphdr *iph = ip_hdr(skb);
47 iph->protocol = XFRM_MODE_SKB_CB(skb)->protocol;
49 #ifndef CONFIG_NETFILTER
51 return -iph->protocol;
54 __skb_push(skb, skb->data - skb_network_header(skb));
55 iph->tot_len = htons(skb->len);
58 if (xo && (xo->flags & XFRM_GRO)) {
59 skb_mac_header_rebuild(skb);
63 NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING,
64 dev_net(skb->dev), NULL, skb, skb->dev, NULL,
65 xfrm4_rcv_encap_finish);
69 /* If it's a keepalive packet, then just eat it.
70 * If it's an encapsulated packet, then pass it to the
72 * Returns 0 if skb passed to xfrm or was dropped.
73 * Returns >0 if skb should be passed to UDP.
74 * Returns <0 if skb should be resubmitted (-ret is protocol)
76 int xfrm4_udp_encap_rcv(struct sock *sk, struct sk_buff *skb)
78 struct udp_sock *up = udp_sk(sk);
85 __u16 encap_type = up->encap_type;
87 /* if this is not encapsulated socket, then just return now */
91 /* If this is a paged skb, make sure we pull up
92 * whatever data we need to look at. */
93 len = skb->len - sizeof(struct udphdr);
94 if (!pskb_may_pull(skb, sizeof(struct udphdr) + min(len, 8)))
97 /* Now we can get the pointers */
99 udpdata = (__u8 *)uh + sizeof(struct udphdr);
100 udpdata32 = (__be32 *)udpdata;
102 switch (encap_type) {
104 case UDP_ENCAP_ESPINUDP:
105 /* Check if this is a keepalive packet. If so, eat it. */
106 if (len == 1 && udpdata[0] == 0xff) {
108 } else if (len > sizeof(struct ip_esp_hdr) && udpdata32[0] != 0) {
109 /* ESP Packet without Non-ESP header */
110 len = sizeof(struct udphdr);
112 /* Must be an IKE packet.. pass it through */
115 case UDP_ENCAP_ESPINUDP_NON_IKE:
116 /* Check if this is a keepalive packet. If so, eat it. */
117 if (len == 1 && udpdata[0] == 0xff) {
119 } else if (len > 2 * sizeof(u32) + sizeof(struct ip_esp_hdr) &&
120 udpdata32[0] == 0 && udpdata32[1] == 0) {
122 /* ESP Packet with Non-IKE marker */
123 len = sizeof(struct udphdr) + 2 * sizeof(u32);
125 /* Must be an IKE packet.. pass it through */
130 /* At this point we are sure that this is an ESPinUDP packet,
131 * so we need to remove 'len' bytes from the packet (the UDP
132 * header and optional ESP marker bytes) and then modify the
133 * protocol to ESP, and then call into the transform receiver.
135 if (skb_unclone(skb, GFP_ATOMIC))
138 /* Now we can update and verify the packet length... */
140 iphlen = iph->ihl << 2;
141 iph->tot_len = htons(ntohs(iph->tot_len) - len);
142 if (skb->len < iphlen + len) {
143 /* packet is too small!?! */
147 /* pull the data buffer up to the ESP header and set the
148 * transport header to point to ESP. Keep UDP on the stack
151 __skb_pull(skb, len);
152 skb_reset_transport_header(skb);
155 return xfrm4_rcv_encap(skb, IPPROTO_ESP, 0, encap_type);
162 int xfrm4_rcv(struct sk_buff *skb)
164 return xfrm4_rcv_spi(skb, ip_hdr(skb)->protocol, 0);
166 EXPORT_SYMBOL(xfrm4_rcv);