1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * xfrm6_input.c: based on net/ipv4/xfrm4_input.c
4 *
5 * Authors:
6 * Mitsuru KANDA @USAGI
7 * Kazunori MIYAZAWA @USAGI
8 * Kunihiro Ishiguro <kunihiro@ipinfusion.com>
9 * YOSHIFUJI Hideaki @USAGI
10 * IPv6 support
11 */
12
13 #include <linux/module.h>
14 #include <linux/string.h>
15 #include <linux/netfilter.h>
16 #include <linux/netfilter_ipv6.h>
17 #include <net/ipv6.h>
18 #include <net/xfrm.h>
19
20 int xfrm6_rcv_spi(struct sk_buff *skb, int nexthdr, __be32 spi,
21 struct ip6_tnl *t)
22 {
23 XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip6 = t;
24 XFRM_SPI_SKB_CB(skb)->family = AF_INET6;
25 XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct ipv6hdr, daddr);
26 return xfrm_input(skb, nexthdr, spi, 0);
27 }
28 EXPORT_SYMBOL(xfrm6_rcv_spi);
29
30 static int xfrm6_transport_finish2(struct net *net, struct sock *sk,
31 struct sk_buff *skb)
32 {
33 if (xfrm_trans_queue(skb, ip6_rcv_finish)) {
34 kfree_skb(skb);
35 return NET_RX_DROP;
36 }
37
38 return 0;
39 }
40
41 int xfrm6_transport_finish(struct sk_buff *skb, int async)
42 {
43 struct xfrm_offload *xo = xfrm_offload(skb);
44 int nhlen = skb->data - skb_network_header(skb);
45
46 skb_network_header(skb)[IP6CB(skb)->nhoff] =
47 XFRM_MODE_SKB_CB(skb)->protocol;
48
49 #ifndef CONFIG_NETFILTER
50 if (!async)
51 return 1;
52 #endif
53
54 __skb_push(skb, nhlen);
55 ipv6_hdr(skb)->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
56 skb_postpush_rcsum(skb, skb_network_header(skb), nhlen);
57
58 if (xo && (xo->flags & XFRM_GRO)) {
59 skb_mac_header_rebuild(skb);
60 skb_reset_transport_header(skb);
61 return 0;
62 }
63
64 NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING,
65 dev_net(skb->dev), NULL, skb, skb->dev, NULL,
66 xfrm6_transport_finish2);
67 return 0;
68 }
69
70 /* If it's a keepalive packet, then just eat it.
71 * If it's an encapsulated packet, then pass it to the
72 * IPsec xfrm input.
73 * Returns 0 if skb passed to xfrm or was dropped.
74 * Returns >0 if skb should be passed to UDP.
75 * Returns <0 if skb should be resubmitted (-ret is protocol)
76 */
77 int xfrm6_udp_encap_rcv(struct sock *sk, struct sk_buff *skb)
78 {
79 struct udp_sock *up = udp_sk(sk);
80 struct udphdr *uh;
81 struct ipv6hdr *ip6h;
82 int len;
83 int ip6hlen = sizeof(struct ipv6hdr);
84
85 __u8 *udpdata;
86 __be32 *udpdata32;
87 __u16 encap_type = up->encap_type;
88
89 /* if this is not encapsulated socket, then just return now */
90 if (!encap_type)
91 return 1;
92
93 /* If this is a paged skb, make sure we pull up
94 * whatever data we need to look at. */
95 len = skb->len - sizeof(struct udphdr);
96 if (!pskb_may_pull(skb, sizeof(struct udphdr) + min(len, 8)))
97 return 1;
98
99 /* Now we can get the pointers */
100 uh = udp_hdr(skb);
101 udpdata = (__u8 *)uh + sizeof(struct udphdr);
102 udpdata32 = (__be32 *)udpdata;
103
104 switch (encap_type) {
105 default:
106 case UDP_ENCAP_ESPINUDP:
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 > sizeof(struct ip_esp_hdr) && udpdata32[0] != 0) {
111 /* ESP Packet without Non-ESP header */
112 len = sizeof(struct udphdr);
113 } else
114 /* Must be an IKE packet.. pass it through */
115 return 1;
116 break;
117 case UDP_ENCAP_ESPINUDP_NON_IKE:
118 /* Check if this is a keepalive packet. If so, eat it. */
119 if (len == 1 && udpdata[0] == 0xff) {
120 goto drop;
121 } else if (len > 2 * sizeof(u32) + sizeof(struct ip_esp_hdr) &&
122 udpdata32[0] == 0 && udpdata32[1] == 0) {
123
124 /* ESP Packet with Non-IKE marker */
125 len = sizeof(struct udphdr) + 2 * sizeof(u32);
126 } else
127 /* Must be an IKE packet.. pass it through */
128 return 1;
129 break;
130 }
131
132 /* At this point we are sure that this is an ESPinUDP packet,
133 * so we need to remove 'len' bytes from the packet (the UDP
134 * header and optional ESP marker bytes) and then modify the
135 * protocol to ESP, and then call into the transform receiver.
136 */
137 if (skb_unclone(skb, GFP_ATOMIC))
138 goto drop;
139
140 /* Now we can update and verify the packet length... */
141 ip6h = ipv6_hdr(skb);
142 ip6h->payload_len = htons(ntohs(ip6h->payload_len) - len);
143 if (skb->len < ip6hlen + len) {
144 /* packet is too small!?! */
145 goto drop;
146 }
147
148 /* pull the data buffer up to the ESP header and set the
149 * transport header to point to ESP. Keep UDP on the stack
150 * for later.
151 */
152 __skb_pull(skb, len);
153 skb_reset_transport_header(skb);
154
155 /* process ESP */
156 return xfrm6_rcv_encap(skb, IPPROTO_ESP, 0, encap_type);
157
158 drop:
159 kfree_skb(skb);
160 return 0;
161 }
162
163 int xfrm6_rcv_tnl(struct sk_buff *skb, struct ip6_tnl *t)
164 {
165 return xfrm6_rcv_spi(skb, skb_network_header(skb)[IP6CB(skb)->nhoff],
166 0, t);
167 }
168 EXPORT_SYMBOL(xfrm6_rcv_tnl);
169
170 int xfrm6_rcv(struct sk_buff *skb)
171 {
172 return xfrm6_rcv_tnl(skb, NULL);
173 }
174 EXPORT_SYMBOL(xfrm6_rcv);
175 int xfrm6_input_addr(struct sk_buff *skb, xfrm_address_t *daddr,
176 xfrm_address_t *saddr, u8 proto)
177 {
178 struct net *net = dev_net(skb->dev);
179 struct xfrm_state *x = NULL;
180 struct sec_path *sp;
181 int i = 0;
182
183 sp = secpath_set(skb);
184 if (!sp) {
185 XFRM_INC_STATS(net, LINUX_MIB_XFRMINERROR);
186 goto drop;
187 }
188
189 if (1 + sp->len == XFRM_MAX_DEPTH) {
190 XFRM_INC_STATS(net, LINUX_MIB_XFRMINBUFFERERROR);
191 goto drop;
192 }
193
194 for (i = 0; i < 3; i++) {
195 xfrm_address_t *dst, *src;
196
197 switch (i) {
198 case 0:
199 dst = daddr;
200 src = saddr;
201 break;
202 case 1:
203 /* lookup state with wild-card source address */
204 dst = daddr;
205 src = (xfrm_address_t *)&in6addr_any;
206 break;
207 default:
208 /* lookup state with wild-card addresses */
209 dst = (xfrm_address_t *)&in6addr_any;
210 src = (xfrm_address_t *)&in6addr_any;
211 break;
212 }
213
214 x = xfrm_state_lookup_byaddr(net, skb->mark, dst, src, proto, AF_INET6);
215 if (!x)
216 continue;
217
218 spin_lock(&x->lock);
219
220 if ((!i || (x->props.flags & XFRM_STATE_WILDRECV)) &&
221 likely(x->km.state == XFRM_STATE_VALID) &&
222 !xfrm_state_check_expire(x)) {
223 spin_unlock(&x->lock);
224 if (x->type->input(x, skb) > 0) {
225 /* found a valid state */
226 break;
227 }
228 } else
229 spin_unlock(&x->lock);
230
231 xfrm_state_put(x);
232 x = NULL;
233 }
234
235 if (!x) {
236 XFRM_INC_STATS(net, LINUX_MIB_XFRMINNOSTATES);
237 xfrm_audit_state_notfound_simple(skb, AF_INET6);
238 goto drop;
239 }
240
241 sp->xvec[sp->len++] = x;
242
243 spin_lock(&x->lock);
244
245 x->curlft.bytes += skb->len;
246 x->curlft.packets++;
247
248 spin_unlock(&x->lock);
249
250 return 1;
251
252 drop:
253 return -1;
254 }
255 EXPORT_SYMBOL(xfrm6_input_addr);
256
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.