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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#include <net/protocol.h>
21#include <net/gro.h>
22
23static int xfrm4_rcv_encap_finish2(struct net *net, struct sock *sk,
24 struct sk_buff *skb)
25{
26 return dst_input(skb);
27}
28
29static inline int xfrm4_rcv_encap_finish(struct net *net, struct sock *sk,
30 struct sk_buff *skb)
31{
32 if (!skb_dst(skb)) {
33 const struct iphdr *iph = ip_hdr(skb);
34
35 if (ip_route_input_noref(skb, iph->daddr, iph->saddr,
36 iph->tos, skb->dev))
37 goto drop;
38 }
39
40 if (xfrm_trans_queue(skb, xfrm4_rcv_encap_finish2))
41 goto drop;
42
43 return 0;
44drop:
45 kfree_skb(skb);
46 return NET_RX_DROP;
47}
48
49int xfrm4_transport_finish(struct sk_buff *skb, int async)
50{
51 struct xfrm_offload *xo = xfrm_offload(skb);
52 struct iphdr *iph = ip_hdr(skb);
53
54 iph->protocol = XFRM_MODE_SKB_CB(skb)->protocol;
55
56#ifndef CONFIG_NETFILTER
57 if (!async)
58 return -iph->protocol;
59#endif
60
61 __skb_push(skb, -skb_network_offset(skb));
62 iph->tot_len = htons(skb->len);
63 ip_send_check(iph);
64
65 if (xo && (xo->flags & XFRM_GRO)) {
66 /* The full l2 header needs to be preserved so that re-injecting the packet at l2
67 * works correctly in the presence of vlan tags.
68 */
69 skb_mac_header_rebuild_full(skb, xo->orig_mac_len);
70 skb_reset_network_header(skb);
71 skb_reset_transport_header(skb);
72 return 0;
73 }
74
75 NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING,
76 dev_net(skb->dev), NULL, skb, skb->dev, NULL,
77 xfrm4_rcv_encap_finish);
78 return 0;
79}
80
81static int __xfrm4_udp_encap_rcv(struct sock *sk, struct sk_buff *skb, bool pull)
82{
83 struct udp_sock *up = udp_sk(sk);
84 struct udphdr *uh;
85 struct iphdr *iph;
86 int iphlen, len;
87 __u8 *udpdata;
88 __be32 *udpdata32;
89 u16 encap_type;
90
91 encap_type = READ_ONCE(up->encap_type);
92 /* if this is not encapsulated socket, then just return now */
93 if (!encap_type)
94 return 1;
95
96 /* If this is a paged skb, make sure we pull up
97 * whatever data we need to look at. */
98 len = skb->len - sizeof(struct udphdr);
99 if (!pskb_may_pull(skb, sizeof(struct udphdr) + min(len, 8)))
100 return 1;
101
102 /* Now we can get the pointers */
103 uh = udp_hdr(skb);
104 udpdata = (__u8 *)uh + sizeof(struct udphdr);
105 udpdata32 = (__be32 *)udpdata;
106
107 switch (encap_type) {
108 default:
109 case UDP_ENCAP_ESPINUDP:
110 /* Check if this is a keepalive packet. If so, eat it. */
111 if (len == 1 && udpdata[0] == 0xff) {
112 return -EINVAL;
113 } else if (len > sizeof(struct ip_esp_hdr) && udpdata32[0] != 0) {
114 /* ESP Packet without Non-ESP header */
115 len = sizeof(struct udphdr);
116 } else
117 /* Must be an IKE packet.. pass it through */
118 return 1;
119 break;
120 case UDP_ENCAP_ESPINUDP_NON_IKE:
121 /* Check if this is a keepalive packet. If so, eat it. */
122 if (len == 1 && udpdata[0] == 0xff) {
123 return -EINVAL;
124 } else if (len > 2 * sizeof(u32) + sizeof(struct ip_esp_hdr) &&
125 udpdata32[0] == 0 && udpdata32[1] == 0) {
126
127 /* ESP Packet with Non-IKE marker */
128 len = sizeof(struct udphdr) + 2 * sizeof(u32);
129 } else
130 /* Must be an IKE packet.. pass it through */
131 return 1;
132 break;
133 }
134
135 /* At this point we are sure that this is an ESPinUDP packet,
136 * so we need to remove 'len' bytes from the packet (the UDP
137 * header and optional ESP marker bytes) and then modify the
138 * protocol to ESP, and then call into the transform receiver.
139 */
140 if (skb_unclone(skb, GFP_ATOMIC))
141 return -EINVAL;
142
143 /* Now we can update and verify the packet length... */
144 iph = ip_hdr(skb);
145 iphlen = iph->ihl << 2;
146 iph->tot_len = htons(ntohs(iph->tot_len) - len);
147 if (skb->len < iphlen + len) {
148 /* packet is too small!?! */
149 return -EINVAL;
150 }
151
152 /* pull the data buffer up to the ESP header and set the
153 * transport header to point to ESP. Keep UDP on the stack
154 * for later.
155 */
156 if (pull) {
157 __skb_pull(skb, len);
158 skb_reset_transport_header(skb);
159 } else {
160 skb_set_transport_header(skb, len);
161 }
162
163 /* process ESP */
164 return 0;
165}
166
167/* If it's a keepalive packet, then just eat it.
168 * If it's an encapsulated packet, then pass it to the
169 * IPsec xfrm input.
170 * Returns 0 if skb passed to xfrm or was dropped.
171 * Returns >0 if skb should be passed to UDP.
172 * Returns <0 if skb should be resubmitted (-ret is protocol)
173 */
174int xfrm4_udp_encap_rcv(struct sock *sk, struct sk_buff *skb)
175{
176 int ret;
177
178 ret = __xfrm4_udp_encap_rcv(sk, skb, true);
179 if (!ret)
180 return xfrm4_rcv_encap(skb, IPPROTO_ESP, 0,
181 udp_sk(sk)->encap_type);
182
183 if (ret < 0) {
184 kfree_skb(skb);
185 return 0;
186 }
187
188 return ret;
189}
190EXPORT_SYMBOL(xfrm4_udp_encap_rcv);
191
192struct sk_buff *xfrm4_gro_udp_encap_rcv(struct sock *sk, struct list_head *head,
193 struct sk_buff *skb)
194{
195 int offset = skb_gro_offset(skb);
196 const struct net_offload *ops;
197 struct sk_buff *pp = NULL;
198 int ret;
199
200 offset = offset - sizeof(struct udphdr);
201
202 if (!pskb_pull(skb, offset))
203 return NULL;
204
205 rcu_read_lock();
206 ops = rcu_dereference(inet_offloads[IPPROTO_ESP]);
207 if (!ops || !ops->callbacks.gro_receive)
208 goto out;
209
210 ret = __xfrm4_udp_encap_rcv(sk, skb, false);
211 if (ret)
212 goto out;
213
214 skb_push(skb, offset);
215 NAPI_GRO_CB(skb)->proto = IPPROTO_UDP;
216
217 pp = call_gro_receive(ops->callbacks.gro_receive, head, skb);
218 rcu_read_unlock();
219
220 return pp;
221
222out:
223 rcu_read_unlock();
224 skb_push(skb, offset);
225 NAPI_GRO_CB(skb)->same_flow = 0;
226 NAPI_GRO_CB(skb)->flush = 1;
227
228 return NULL;
229}
230EXPORT_SYMBOL(xfrm4_gro_udp_encap_rcv);
231
232int xfrm4_rcv(struct sk_buff *skb)
233{
234 return xfrm4_rcv_spi(skb, ip_hdr(skb)->protocol, 0);
235}
236EXPORT_SYMBOL(xfrm4_rcv);