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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/slab.h>
13#include <linux/module.h>
14#include <linux/string.h>
15#include <linux/netfilter.h>
16#include <linux/netfilter_ipv4.h>
17#include <net/ip.h>
18#include <net/xfrm.h>
19
20int xfrm4_extract_input(struct xfrm_state *x, struct sk_buff *skb)
21{
22 return xfrm4_extract_header(skb);
23}
24
25static inline int xfrm4_rcv_encap_finish(struct sk_buff *skb)
26{
27 if (skb_dst(skb) == NULL) {
28 const struct iphdr *iph = ip_hdr(skb);
29
30 if (ip_route_input_noref(skb, iph->daddr, iph->saddr,
31 iph->tos, skb->dev))
32 goto drop;
33 }
34 return dst_input(skb);
35drop:
36 kfree_skb(skb);
37 return NET_RX_DROP;
38}
39
40int xfrm4_rcv_encap(struct sk_buff *skb, int nexthdr, __be32 spi,
41 int encap_type)
42{
43 XFRM_SPI_SKB_CB(skb)->family = AF_INET;
44 XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct iphdr, daddr);
45 return xfrm_input(skb, nexthdr, spi, encap_type);
46}
47EXPORT_SYMBOL(xfrm4_rcv_encap);
48
49int xfrm4_transport_finish(struct sk_buff *skb, int async)
50{
51 struct iphdr *iph = ip_hdr(skb);
52
53 iph->protocol = XFRM_MODE_SKB_CB(skb)->protocol;
54
55#ifndef CONFIG_NETFILTER
56 if (!async)
57 return -iph->protocol;
58#endif
59
60 __skb_push(skb, skb->data - skb_network_header(skb));
61 iph->tot_len = htons(skb->len);
62 ip_send_check(iph);
63
64 NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, skb, skb->dev, NULL,
65 xfrm4_rcv_encap_finish);
66 return 0;
67}
68
69/* 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;
82
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
154 /* process ESP */
155 return xfrm4_rcv_encap(skb, IPPROTO_ESP, 0, encap_type);
156
157drop:
158 kfree_skb(skb);
159 return 0;
160}
161
162int xfrm4_rcv(struct sk_buff *skb)
163{
164 return xfrm4_rcv_spi(skb, ip_hdr(skb)->protocol, 0);
165}
166EXPORT_SYMBOL(xfrm4_rcv);
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/slab.h>
13#include <linux/module.h>
14#include <linux/string.h>
15#include <linux/netfilter.h>
16#include <linux/netfilter_ipv4.h>
17#include <net/ip.h>
18#include <net/xfrm.h>
19
20int xfrm4_extract_input(struct xfrm_state *x, struct sk_buff *skb)
21{
22 return xfrm4_extract_header(skb);
23}
24
25static inline int xfrm4_rcv_encap_finish(struct sk_buff *skb)
26{
27 if (skb_dst(skb) == NULL) {
28 const struct iphdr *iph = ip_hdr(skb);
29
30 if (ip_route_input_noref(skb, iph->daddr, iph->saddr,
31 iph->tos, skb->dev))
32 goto drop;
33 }
34 return dst_input(skb);
35drop:
36 kfree_skb(skb);
37 return NET_RX_DROP;
38}
39
40int xfrm4_transport_finish(struct sk_buff *skb, int async)
41{
42 struct iphdr *iph = ip_hdr(skb);
43
44 iph->protocol = XFRM_MODE_SKB_CB(skb)->protocol;
45
46#ifndef CONFIG_NETFILTER
47 if (!async)
48 return -iph->protocol;
49#endif
50
51 __skb_push(skb, skb->data - skb_network_header(skb));
52 iph->tot_len = htons(skb->len);
53 ip_send_check(iph);
54
55 NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, skb, skb->dev, NULL,
56 xfrm4_rcv_encap_finish);
57 return 0;
58}
59
60/* If it's a keepalive packet, then just eat it.
61 * If it's an encapsulated packet, then pass it to the
62 * IPsec xfrm input.
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)
66 */
67int xfrm4_udp_encap_rcv(struct sock *sk, struct sk_buff *skb)
68{
69 struct udp_sock *up = udp_sk(sk);
70 struct udphdr *uh;
71 struct iphdr *iph;
72 int iphlen, len;
73
74 __u8 *udpdata;
75 __be32 *udpdata32;
76 __u16 encap_type = up->encap_type;
77
78 /* if this is not encapsulated socket, then just return now */
79 if (!encap_type)
80 return 1;
81
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)))
86 return 1;
87
88 /* Now we can get the pointers */
89 uh = udp_hdr(skb);
90 udpdata = (__u8 *)uh + sizeof(struct udphdr);
91 udpdata32 = (__be32 *)udpdata;
92
93 switch (encap_type) {
94 default:
95 case UDP_ENCAP_ESPINUDP:
96 /* Check if this is a keepalive packet. If so, eat it. */
97 if (len == 1 && udpdata[0] == 0xff) {
98 goto drop;
99 } else if (len > sizeof(struct ip_esp_hdr) && udpdata32[0] != 0) {
100 /* ESP Packet without Non-ESP header */
101 len = sizeof(struct udphdr);
102 } else
103 /* Must be an IKE packet.. pass it through */
104 return 1;
105 break;
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) {
109 goto drop;
110 } else if (len > 2 * sizeof(u32) + sizeof(struct ip_esp_hdr) &&
111 udpdata32[0] == 0 && udpdata32[1] == 0) {
112
113 /* ESP Packet with Non-IKE marker */
114 len = sizeof(struct udphdr) + 2 * sizeof(u32);
115 } else
116 /* Must be an IKE packet.. pass it through */
117 return 1;
118 break;
119 }
120
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.
125 */
126 if (skb_unclone(skb, GFP_ATOMIC))
127 goto drop;
128
129 /* Now we can update and verify the packet length... */
130 iph = ip_hdr(skb);
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!?! */
135 goto drop;
136 }
137
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
140 * for later.
141 */
142 __skb_pull(skb, len);
143 skb_reset_transport_header(skb);
144
145 /* process ESP */
146 return xfrm4_rcv_encap(skb, IPPROTO_ESP, 0, encap_type);
147
148drop:
149 kfree_skb(skb);
150 return 0;
151}
152
153int xfrm4_rcv(struct sk_buff *skb)
154{
155 return xfrm4_rcv_spi(skb, ip_hdr(skb)->protocol, 0);
156}
157EXPORT_SYMBOL(xfrm4_rcv);