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
xfrm4_rcv_encap_finish2(struct net * net,struct sock * sk,struct sk_buff * skb)21 static int xfrm4_rcv_encap_finish2(struct net *net, struct sock *sk,
22 struct sk_buff *skb)
23 {
24 return dst_input(skb);
25 }
26
xfrm4_rcv_encap_finish(struct net * net,struct sock * sk,struct sk_buff * skb)27 static 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;
42 drop:
43 kfree_skb(skb);
44 return NET_RX_DROP;
45 }
46
xfrm4_transport_finish(struct sk_buff * skb,int async)47 int 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 */
xfrm4_udp_encap_rcv(struct sock * sk,struct sk_buff * skb)82 int 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
163 drop:
164 kfree_skb(skb);
165 return 0;
166 }
167 EXPORT_SYMBOL(xfrm4_udp_encap_rcv);
168
xfrm4_rcv(struct sk_buff * skb)169 int xfrm4_rcv(struct sk_buff *skb)
170 {
171 return xfrm4_rcv_spi(skb, ip_hdr(skb)->protocol, 0);
172 }
173 EXPORT_SYMBOL(xfrm4_rcv);
174
