blob: 06814b6216dc1bc71fedc9924b23d74b817a38d8 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * xfrm4_input.c
3 *
4 * Changes:
5 * YOSHIFUJI Hideaki @USAGI
6 * Split up af-specific portion
7 * Derek Atkins <derek@ihtfp.com>
8 * Add Encapsulation support
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +09009 *
Linus Torvalds1da177e2005-04-16 15:20:36 -070010 */
11
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090012#include <linux/slab.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070013#include <linux/module.h>
14#include <linux/string.h>
Patrick McHardyb05e1062006-01-06 23:03:34 -080015#include <linux/netfilter.h>
16#include <linux/netfilter_ipv4.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070017#include <net/ip.h>
18#include <net/xfrm.h>
19
Herbert Xu227620e2007-11-13 21:41:28 -080020int xfrm4_extract_input(struct xfrm_state *x, struct sk_buff *skb)
21{
22 return xfrm4_extract_header(skb);
23}
24
Patrick McHardyb05e1062006-01-06 23:03:34 -080025static inline int xfrm4_rcv_encap_finish(struct sk_buff *skb)
26{
Eric Dumazetadf30902009-06-02 05:19:30 +000027 if (skb_dst(skb) == NULL) {
Arnaldo Carvalho de Meloeddc9ec2007-04-20 22:47:35 -070028 const struct iphdr *iph = ip_hdr(skb);
29
Eric Dumazet4a944452010-05-10 11:33:06 +000030 if (ip_route_input_noref(skb, iph->daddr, iph->saddr,
31 iph->tos, skb->dev))
Patrick McHardyb05e1062006-01-06 23:03:34 -080032 goto drop;
33 }
34 return dst_input(skb);
35drop:
36 kfree_skb(skb);
37 return NET_RX_DROP;
38}
Patrick McHardyb05e1062006-01-06 23:03:34 -080039
Herbert Xuc4541b42007-10-17 21:28:53 -070040int xfrm4_rcv_encap(struct sk_buff *skb, int nexthdr, __be32 spi,
41 int encap_type)
Linus Torvalds1da177e2005-04-16 15:20:36 -070042{
Herbert Xu2fcb45b2007-12-03 22:54:12 -080043 XFRM_SPI_SKB_CB(skb)->family = AF_INET;
Herbert Xu716062f2007-11-13 21:44:23 -080044 XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct iphdr, daddr);
45 return xfrm_input(skb, nexthdr, spi, encap_type);
Linus Torvalds1da177e2005-04-16 15:20:36 -070046}
Herbert Xuc4541b42007-10-17 21:28:53 -070047EXPORT_SYMBOL(xfrm4_rcv_encap);
James Chapman067b2072007-07-05 17:08:05 -070048
Herbert Xu716062f2007-11-13 21:44:23 -080049int xfrm4_transport_finish(struct sk_buff *skb, int async)
50{
Herbert Xu60d5fcf2007-11-19 18:47:58 -080051 struct iphdr *iph = ip_hdr(skb);
52
53 iph->protocol = XFRM_MODE_SKB_CB(skb)->protocol;
54
Herbert Xu0883ae02007-12-30 21:10:14 -080055#ifndef CONFIG_NETFILTER
56 if (!async)
57 return -iph->protocol;
58#endif
59
Herbert Xu716062f2007-11-13 21:44:23 -080060 __skb_push(skb, skb->data - skb_network_header(skb));
Herbert Xu60d5fcf2007-11-19 18:47:58 -080061 iph->tot_len = htons(skb->len);
62 ip_send_check(iph);
Herbert Xu716062f2007-11-13 21:44:23 -080063
Jan Engelhardt9bbc7682010-03-23 04:07:29 +010064 NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, skb, skb->dev, NULL,
Herbert Xu716062f2007-11-13 21:44:23 -080065 xfrm4_rcv_encap_finish);
66 return 0;
Herbert Xu716062f2007-11-13 21:44:23 -080067}
68
James Chapman067b2072007-07-05 17:08:05 -070069/* If it's a keepalive packet, then just eat it.
70 * If it's an encapsulated packet, then pass it to the
71 * IPsec xfrm input.
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)
75 */
76int xfrm4_udp_encap_rcv(struct sock *sk, struct sk_buff *skb)
77{
78 struct udp_sock *up = udp_sk(sk);
79 struct udphdr *uh;
80 struct iphdr *iph;
81 int iphlen, len;
James Chapman067b2072007-07-05 17:08:05 -070082
83 __u8 *udpdata;
84 __be32 *udpdata32;
85 __u16 encap_type = up->encap_type;
86
87 /* if this is not encapsulated socket, then just return now */
88 if (!encap_type)
89 return 1;
90
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)))
95 return 1;
96
97 /* Now we can get the pointers */
98 uh = udp_hdr(skb);
99 udpdata = (__u8 *)uh + sizeof(struct udphdr);
100 udpdata32 = (__be32 *)udpdata;
101
102 switch (encap_type) {
103 default:
104 case UDP_ENCAP_ESPINUDP:
105 /* Check if this is a keepalive packet. If so, eat it. */
106 if (len == 1 && udpdata[0] == 0xff) {
107 goto drop;
108 } else if (len > sizeof(struct ip_esp_hdr) && udpdata32[0] != 0) {
109 /* ESP Packet without Non-ESP header */
110 len = sizeof(struct udphdr);
111 } else
112 /* Must be an IKE packet.. pass it through */
113 return 1;
114 break;
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) {
118 goto drop;
119 } else if (len > 2 * sizeof(u32) + sizeof(struct ip_esp_hdr) &&
120 udpdata32[0] == 0 && udpdata32[1] == 0) {
121
122 /* ESP Packet with Non-IKE marker */
123 len = sizeof(struct udphdr) + 2 * sizeof(u32);
124 } else
125 /* Must be an IKE packet.. pass it through */
126 return 1;
127 break;
128 }
129
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.
134 */
135 if (skb_cloned(skb) && pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
136 goto drop;
137
138 /* Now we can update and verify the packet length... */
139 iph = ip_hdr(skb);
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!?! */
144 goto drop;
145 }
146
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
149 * for later.
150 */
151 __skb_pull(skb, len);
152 skb_reset_transport_header(skb);
153
James Chapman067b2072007-07-05 17:08:05 -0700154 /* process ESP */
Herbert Xuf2712fd2008-12-26 01:31:18 -0800155 return xfrm4_rcv_encap(skb, IPPROTO_ESP, 0, encap_type);
James Chapman067b2072007-07-05 17:08:05 -0700156
157drop:
158 kfree_skb(skb);
159 return 0;
160}
161
162int xfrm4_rcv(struct sk_buff *skb)
163{
Herbert Xuc4541b42007-10-17 21:28:53 -0700164 return xfrm4_rcv_spi(skb, ip_hdr(skb)->protocol, 0);
James Chapman067b2072007-07-05 17:08:05 -0700165}
James Chapman067b2072007-07-05 17:08:05 -0700166EXPORT_SYMBOL(xfrm4_rcv);