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
xfrm6_rcv_spi(struct sk_buff * skb,int nexthdr,__be32 spi,struct ip6_tnl * t)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
xfrm6_transport_finish2(struct net * net,struct sock * sk,struct sk_buff * skb)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
xfrm6_transport_finish(struct sk_buff * skb,int async)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 /* The full l2 header needs to be preserved so that re-injecting the packet at l2
60 * works correctly in the presence of vlan tags.
61 */
62 skb_mac_header_rebuild_full(skb, xo->orig_mac_len);
63 skb_reset_network_header(skb);
64 skb_reset_transport_header(skb);
65 return 0;
66 }
67
68 NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING,
69 dev_net(skb->dev), NULL, skb, skb->dev, NULL,
70 xfrm6_transport_finish2);
71 return 0;
72 }
73
74 /* If it's a keepalive packet, then just eat it.
75 * If it's an encapsulated packet, then pass it to the
76 * IPsec xfrm input.
77 * Returns 0 if skb passed to xfrm or was dropped.
78 * Returns >0 if skb should be passed to UDP.
79 * Returns <0 if skb should be resubmitted (-ret is protocol)
80 */
xfrm6_udp_encap_rcv(struct sock * sk,struct sk_buff * skb)81 int xfrm6_udp_encap_rcv(struct sock *sk, struct sk_buff *skb)
82 {
83 struct udp_sock *up = udp_sk(sk);
84 struct udphdr *uh;
85 struct ipv6hdr *ip6h;
86 int len;
87 int ip6hlen = sizeof(struct ipv6hdr);
88 __u8 *udpdata;
89 __be32 *udpdata32;
90 u16 encap_type;
91
92 if (skb->protocol == htons(ETH_P_IP))
93 return xfrm4_udp_encap_rcv(sk, skb);
94
95 encap_type = READ_ONCE(up->encap_type);
96 /* if this is not encapsulated socket, then just return now */
97 if (!encap_type)
98 return 1;
99
100 /* If this is a paged skb, make sure we pull up
101 * whatever data we need to look at. */
102 len = skb->len - sizeof(struct udphdr);
103 if (!pskb_may_pull(skb, sizeof(struct udphdr) + min(len, 8)))
104 return 1;
105
106 /* Now we can get the pointers */
107 uh = udp_hdr(skb);
108 udpdata = (__u8 *)uh + sizeof(struct udphdr);
109 udpdata32 = (__be32 *)udpdata;
110
111 switch (encap_type) {
112 default:
113 case UDP_ENCAP_ESPINUDP:
114 /* Check if this is a keepalive packet. If so, eat it. */
115 if (len == 1 && udpdata[0] == 0xff) {
116 goto drop;
117 } else if (len > sizeof(struct ip_esp_hdr) && udpdata32[0] != 0) {
118 /* ESP Packet without Non-ESP header */
119 len = sizeof(struct udphdr);
120 } else
121 /* Must be an IKE packet.. pass it through */
122 return 1;
123 break;
124 case UDP_ENCAP_ESPINUDP_NON_IKE:
125 /* Check if this is a keepalive packet. If so, eat it. */
126 if (len == 1 && udpdata[0] == 0xff) {
127 goto drop;
128 } else if (len > 2 * sizeof(u32) + sizeof(struct ip_esp_hdr) &&
129 udpdata32[0] == 0 && udpdata32[1] == 0) {
130
131 /* ESP Packet with Non-IKE marker */
132 len = sizeof(struct udphdr) + 2 * sizeof(u32);
133 } else
134 /* Must be an IKE packet.. pass it through */
135 return 1;
136 break;
137 }
138
139 /* At this point we are sure that this is an ESPinUDP packet,
140 * so we need to remove 'len' bytes from the packet (the UDP
141 * header and optional ESP marker bytes) and then modify the
142 * protocol to ESP, and then call into the transform receiver.
143 */
144 if (skb_unclone(skb, GFP_ATOMIC))
145 goto drop;
146
147 /* Now we can update and verify the packet length... */
148 ip6h = ipv6_hdr(skb);
149 ip6h->payload_len = htons(ntohs(ip6h->payload_len) - len);
150 if (skb->len < ip6hlen + len) {
151 /* packet is too small!?! */
152 goto drop;
153 }
154
155 /* pull the data buffer up to the ESP header and set the
156 * transport header to point to ESP. Keep UDP on the stack
157 * for later.
158 */
159 __skb_pull(skb, len);
160 skb_reset_transport_header(skb);
161
162 /* process ESP */
163 return xfrm6_rcv_encap(skb, IPPROTO_ESP, 0, encap_type);
164
165 drop:
166 kfree_skb(skb);
167 return 0;
168 }
169
xfrm6_rcv_tnl(struct sk_buff * skb,struct ip6_tnl * t)170 int xfrm6_rcv_tnl(struct sk_buff *skb, struct ip6_tnl *t)
171 {
172 return xfrm6_rcv_spi(skb, skb_network_header(skb)[IP6CB(skb)->nhoff],
173 0, t);
174 }
175 EXPORT_SYMBOL(xfrm6_rcv_tnl);
176
xfrm6_rcv(struct sk_buff * skb)177 int xfrm6_rcv(struct sk_buff *skb)
178 {
179 return xfrm6_rcv_tnl(skb, NULL);
180 }
181 EXPORT_SYMBOL(xfrm6_rcv);
xfrm6_input_addr(struct sk_buff * skb,xfrm_address_t * daddr,xfrm_address_t * saddr,u8 proto)182 int xfrm6_input_addr(struct sk_buff *skb, xfrm_address_t *daddr,
183 xfrm_address_t *saddr, u8 proto)
184 {
185 struct net *net = dev_net(skb->dev);
186 struct xfrm_state *x = NULL;
187 struct sec_path *sp;
188 int i = 0;
189
190 sp = secpath_set(skb);
191 if (!sp) {
192 XFRM_INC_STATS(net, LINUX_MIB_XFRMINERROR);
193 goto drop;
194 }
195
196 if (1 + sp->len == XFRM_MAX_DEPTH) {
197 XFRM_INC_STATS(net, LINUX_MIB_XFRMINBUFFERERROR);
198 goto drop;
199 }
200
201 for (i = 0; i < 3; i++) {
202 xfrm_address_t *dst, *src;
203
204 switch (i) {
205 case 0:
206 dst = daddr;
207 src = saddr;
208 break;
209 case 1:
210 /* lookup state with wild-card source address */
211 dst = daddr;
212 src = (xfrm_address_t *)&in6addr_any;
213 break;
214 default:
215 /* lookup state with wild-card addresses */
216 dst = (xfrm_address_t *)&in6addr_any;
217 src = (xfrm_address_t *)&in6addr_any;
218 break;
219 }
220
221 x = xfrm_state_lookup_byaddr(net, skb->mark, dst, src, proto, AF_INET6);
222 if (!x)
223 continue;
224
225 spin_lock(&x->lock);
226
227 if ((!i || (x->props.flags & XFRM_STATE_WILDRECV)) &&
228 likely(x->km.state == XFRM_STATE_VALID) &&
229 !xfrm_state_check_expire(x)) {
230 spin_unlock(&x->lock);
231 if (x->type->input(x, skb) > 0) {
232 /* found a valid state */
233 break;
234 }
235 } else
236 spin_unlock(&x->lock);
237
238 xfrm_state_put(x);
239 x = NULL;
240 }
241
242 if (!x) {
243 XFRM_INC_STATS(net, LINUX_MIB_XFRMINNOSTATES);
244 xfrm_audit_state_notfound_simple(skb, AF_INET6);
245 goto drop;
246 }
247
248 sp->xvec[sp->len++] = x;
249
250 spin_lock(&x->lock);
251
252 x->curlft.bytes += skb->len;
253 x->curlft.packets++;
254
255 spin_unlock(&x->lock);
256
257 return 1;
258
259 drop:
260 return -1;
261 }
262 EXPORT_SYMBOL(xfrm6_input_addr);
263