1 /*
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
9 *
10 */
11
12 #include <linux/module.h>
13 #include <linux/string.h>
14 #include <linux/netfilter.h>
15 #include <linux/netfilter_ipv4.h>
16 #include <net/ip.h>
17 #include <net/xfrm.h>
18
xfrm4_extract_input(struct xfrm_state * x,struct sk_buff * skb)19 int xfrm4_extract_input(struct xfrm_state *x, struct sk_buff *skb)
20 {
21 return xfrm4_extract_header(skb);
22 }
23
xfrm4_rcv_encap_finish(struct sk_buff * skb)24 static inline int xfrm4_rcv_encap_finish(struct sk_buff *skb)
25 {
26 if (skb->dst == NULL) {
27 const struct iphdr *iph = ip_hdr(skb);
28
29 if (ip_route_input(skb, iph->daddr, iph->saddr, iph->tos,
30 skb->dev))
31 goto drop;
32 }
33 return dst_input(skb);
34 drop:
35 kfree_skb(skb);
36 return NET_RX_DROP;
37 }
38
xfrm4_rcv_encap(struct sk_buff * skb,int nexthdr,__be32 spi,int encap_type)39 int xfrm4_rcv_encap(struct sk_buff *skb, int nexthdr, __be32 spi,
40 int encap_type)
41 {
42 XFRM_SPI_SKB_CB(skb)->family = AF_INET;
43 XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct iphdr, daddr);
44 return xfrm_input(skb, nexthdr, spi, encap_type);
45 }
46 EXPORT_SYMBOL(xfrm4_rcv_encap);
47
xfrm4_transport_finish(struct sk_buff * skb,int async)48 int xfrm4_transport_finish(struct sk_buff *skb, int async)
49 {
50 struct iphdr *iph = ip_hdr(skb);
51
52 iph->protocol = XFRM_MODE_SKB_CB(skb)->protocol;
53
54 #ifndef CONFIG_NETFILTER
55 if (!async)
56 return -iph->protocol;
57 #endif
58
59 __skb_push(skb, skb->data - skb_network_header(skb));
60 iph->tot_len = htons(skb->len);
61 ip_send_check(iph);
62
63 NF_HOOK(PF_INET, NF_INET_PRE_ROUTING, skb, skb->dev, NULL,
64 xfrm4_rcv_encap_finish);
65 return 0;
66 }
67
68 /* If it's a keepalive packet, then just eat it.
69 * If it's an encapsulated packet, then pass it to the
70 * IPsec xfrm input.
71 * Returns 0 if skb passed to xfrm or was dropped.
72 * Returns >0 if skb should be passed to UDP.
73 * Returns <0 if skb should be resubmitted (-ret is protocol)
74 */
xfrm4_udp_encap_rcv(struct sock * sk,struct sk_buff * skb)75 int xfrm4_udp_encap_rcv(struct sock *sk, struct sk_buff *skb)
76 {
77 struct udp_sock *up = udp_sk(sk);
78 struct udphdr *uh;
79 struct iphdr *iph;
80 int iphlen, len;
81
82 __u8 *udpdata;
83 __be32 *udpdata32;
84 __u16 encap_type = up->encap_type;
85
86 /* if this is not encapsulated socket, then just return now */
87 if (!encap_type)
88 return 1;
89
90 /* If this is a paged skb, make sure we pull up
91 * whatever data we need to look at. */
92 len = skb->len - sizeof(struct udphdr);
93 if (!pskb_may_pull(skb, sizeof(struct udphdr) + min(len, 8)))
94 return 1;
95
96 /* Now we can get the pointers */
97 uh = udp_hdr(skb);
98 udpdata = (__u8 *)uh + sizeof(struct udphdr);
99 udpdata32 = (__be32 *)udpdata;
100
101 switch (encap_type) {
102 default:
103 case UDP_ENCAP_ESPINUDP:
104 /* Check if this is a keepalive packet. If so, eat it. */
105 if (len == 1 && udpdata[0] == 0xff) {
106 goto drop;
107 } else if (len > sizeof(struct ip_esp_hdr) && udpdata32[0] != 0) {
108 /* ESP Packet without Non-ESP header */
109 len = sizeof(struct udphdr);
110 } else
111 /* Must be an IKE packet.. pass it through */
112 return 1;
113 break;
114 case UDP_ENCAP_ESPINUDP_NON_IKE:
115 /* Check if this is a keepalive packet. If so, eat it. */
116 if (len == 1 && udpdata[0] == 0xff) {
117 goto drop;
118 } else if (len > 2 * sizeof(u32) + sizeof(struct ip_esp_hdr) &&
119 udpdata32[0] == 0 && udpdata32[1] == 0) {
120
121 /* ESP Packet with Non-IKE marker */
122 len = sizeof(struct udphdr) + 2 * sizeof(u32);
123 } else
124 /* Must be an IKE packet.. pass it through */
125 return 1;
126 break;
127 }
128
129 /* At this point we are sure that this is an ESPinUDP packet,
130 * so we need to remove 'len' bytes from the packet (the UDP
131 * header and optional ESP marker bytes) and then modify the
132 * protocol to ESP, and then call into the transform receiver.
133 */
134 if (skb_cloned(skb) && pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
135 goto drop;
136
137 /* Now we can update and verify the packet length... */
138 iph = ip_hdr(skb);
139 iphlen = iph->ihl << 2;
140 iph->tot_len = htons(ntohs(iph->tot_len) - len);
141 if (skb->len < iphlen + len) {
142 /* packet is too small!?! */
143 goto drop;
144 }
145
146 /* pull the data buffer up to the ESP header and set the
147 * transport header to point to ESP. Keep UDP on the stack
148 * for later.
149 */
150 __skb_pull(skb, len);
151 skb_reset_transport_header(skb);
152
153 /* process ESP */
154 return xfrm4_rcv_encap(skb, IPPROTO_ESP, 0, encap_type);
155
156 drop:
157 kfree_skb(skb);
158 return 0;
159 }
160
xfrm4_rcv(struct sk_buff * skb)161 int xfrm4_rcv(struct sk_buff *skb)
162 {
163 return xfrm4_rcv_spi(skb, ip_hdr(skb)->protocol, 0);
164 }
165
166 EXPORT_SYMBOL(xfrm4_rcv);
167