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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_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);
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * xfrm4_input.c
4 *
5 * Changes:
6 * YOSHIFUJI Hideaki @USAGI
7 * Split up af-specific portion
8 * Derek Atkins <derek@ihtfp.com>
9 * Add Encapsulation support
10 *
11 */
12
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>
18#include <net/ip.h>
19#include <net/xfrm.h>
20
21static int xfrm4_rcv_encap_finish2(struct net *net, struct sock *sk,
22 struct sk_buff *skb)
23{
24 return dst_input(skb);
25}
26
27static inline int xfrm4_rcv_encap_finish(struct net *net, struct sock *sk,
28 struct sk_buff *skb)
29{
30 if (!skb_dst(skb)) {
31 const struct iphdr *iph = ip_hdr(skb);
32
33 if (ip_route_input_noref(skb, iph->daddr, iph->saddr,
34 iph->tos, skb->dev))
35 goto drop;
36 }
37
38 if (xfrm_trans_queue(skb, xfrm4_rcv_encap_finish2))
39 goto drop;
40
41 return 0;
42drop:
43 kfree_skb(skb);
44 return NET_RX_DROP;
45}
46
47int xfrm4_transport_finish(struct sk_buff *skb, int async)
48{
49 struct xfrm_offload *xo = xfrm_offload(skb);
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 if (xo && (xo->flags & XFRM_GRO)) {
64 skb_mac_header_rebuild(skb);
65 skb_reset_transport_header(skb);
66 return 0;
67 }
68
69 NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING,
70 dev_net(skb->dev), NULL, skb, skb->dev, NULL,
71 xfrm4_rcv_encap_finish);
72 return 0;
73}
74
75/* If it's a keepalive packet, then just eat it.
76 * If it's an encapsulated packet, then pass it to the
77 * IPsec xfrm input.
78 * Returns 0 if skb passed to xfrm or was dropped.
79 * Returns >0 if skb should be passed to UDP.
80 * Returns <0 if skb should be resubmitted (-ret is protocol)
81 */
82int xfrm4_udp_encap_rcv(struct sock *sk, struct sk_buff *skb)
83{
84 struct udp_sock *up = udp_sk(sk);
85 struct udphdr *uh;
86 struct iphdr *iph;
87 int iphlen, len;
88
89 __u8 *udpdata;
90 __be32 *udpdata32;
91 __u16 encap_type = up->encap_type;
92
93 /* if this is not encapsulated socket, then just return now */
94 if (!encap_type)
95 return 1;
96
97 /* If this is a paged skb, make sure we pull up
98 * whatever data we need to look at. */
99 len = skb->len - sizeof(struct udphdr);
100 if (!pskb_may_pull(skb, sizeof(struct udphdr) + min(len, 8)))
101 return 1;
102
103 /* Now we can get the pointers */
104 uh = udp_hdr(skb);
105 udpdata = (__u8 *)uh + sizeof(struct udphdr);
106 udpdata32 = (__be32 *)udpdata;
107
108 switch (encap_type) {
109 default:
110 case UDP_ENCAP_ESPINUDP:
111 /* Check if this is a keepalive packet. If so, eat it. */
112 if (len == 1 && udpdata[0] == 0xff) {
113 goto drop;
114 } else if (len > sizeof(struct ip_esp_hdr) && udpdata32[0] != 0) {
115 /* ESP Packet without Non-ESP header */
116 len = sizeof(struct udphdr);
117 } else
118 /* Must be an IKE packet.. pass it through */
119 return 1;
120 break;
121 case UDP_ENCAP_ESPINUDP_NON_IKE:
122 /* Check if this is a keepalive packet. If so, eat it. */
123 if (len == 1 && udpdata[0] == 0xff) {
124 goto drop;
125 } else if (len > 2 * sizeof(u32) + sizeof(struct ip_esp_hdr) &&
126 udpdata32[0] == 0 && udpdata32[1] == 0) {
127
128 /* ESP Packet with Non-IKE marker */
129 len = sizeof(struct udphdr) + 2 * sizeof(u32);
130 } else
131 /* Must be an IKE packet.. pass it through */
132 return 1;
133 break;
134 }
135
136 /* At this point we are sure that this is an ESPinUDP packet,
137 * so we need to remove 'len' bytes from the packet (the UDP
138 * header and optional ESP marker bytes) and then modify the
139 * protocol to ESP, and then call into the transform receiver.
140 */
141 if (skb_unclone(skb, GFP_ATOMIC))
142 goto drop;
143
144 /* Now we can update and verify the packet length... */
145 iph = ip_hdr(skb);
146 iphlen = iph->ihl << 2;
147 iph->tot_len = htons(ntohs(iph->tot_len) - len);
148 if (skb->len < iphlen + len) {
149 /* packet is too small!?! */
150 goto drop;
151 }
152
153 /* pull the data buffer up to the ESP header and set the
154 * transport header to point to ESP. Keep UDP on the stack
155 * for later.
156 */
157 __skb_pull(skb, len);
158 skb_reset_transport_header(skb);
159
160 /* process ESP */
161 return xfrm4_rcv_encap(skb, IPPROTO_ESP, 0, encap_type);
162
163drop:
164 kfree_skb(skb);
165 return 0;
166}
167
168int xfrm4_rcv(struct sk_buff *skb)
169{
170 return xfrm4_rcv_spi(skb, ip_hdr(skb)->protocol, 0);
171}
172EXPORT_SYMBOL(xfrm4_rcv);