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#include <net/protocol.h>
20#include <net/gro.h>
21
22int xfrm6_rcv_spi(struct sk_buff *skb, int nexthdr, __be32 spi,
23 struct ip6_tnl *t)
24{
25 XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip6 = t;
26 XFRM_SPI_SKB_CB(skb)->family = AF_INET6;
27 XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct ipv6hdr, daddr);
28 return xfrm_input(skb, nexthdr, spi, encap_type: 0);
29}
30EXPORT_SYMBOL(xfrm6_rcv_spi);
31
32static int xfrm6_transport_finish2(struct net *net, struct sock *sk,
33 struct sk_buff *skb)
34{
35 if (xfrm_trans_queue(skb, finish: ip6_rcv_finish)) {
36 kfree_skb(skb);
37 return NET_RX_DROP;
38 }
39
40 return 0;
41}
42
43int xfrm6_transport_finish(struct sk_buff *skb, int async)
44{
45 struct xfrm_offload *xo = xfrm_offload(skb);
46 int nhlen = -skb_network_offset(skb);
47
48 skb_network_header(skb)[IP6CB(skb)->nhoff] =
49 XFRM_MODE_SKB_CB(skb)->protocol;
50
51#ifndef CONFIG_NETFILTER
52 if (!async)
53 return 1;
54#endif
55
56 __skb_push(skb, len: nhlen);
57 ipv6_hdr(skb)->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
58 skb_postpush_rcsum(skb, start: skb_network_header(skb), len: nhlen);
59
60 if (xo && (xo->flags & XFRM_GRO)) {
61 /* The full l2 header needs to be preserved so that re-injecting the packet at l2
62 * works correctly in the presence of vlan tags.
63 */
64 skb_mac_header_rebuild_full(skb, full_mac_len: xo->orig_mac_len);
65 skb_reset_network_header(skb);
66 skb_reset_transport_header(skb);
67 return 0;
68 }
69
70 NF_HOOK(pf: NFPROTO_IPV6, hook: NF_INET_PRE_ROUTING,
71 net: dev_net(dev: skb->dev), NULL, skb, in: skb->dev, NULL,
72 okfn: xfrm6_transport_finish2);
73 return 0;
74}
75
76static int __xfrm6_udp_encap_rcv(struct sock *sk, struct sk_buff *skb, bool pull)
77{
78 struct udp_sock *up = udp_sk(sk);
79 struct udphdr *uh;
80 struct ipv6hdr *ip6h;
81 int len;
82 int ip6hlen = sizeof(struct ipv6hdr);
83 __u8 *udpdata;
84 __be32 *udpdata32;
85 u16 encap_type;
86
87 encap_type = READ_ONCE(up->encap_type);
88 /* if this is not encapsulated socket, then just return now */
89 if (!encap_type)
90 return 1;
91
92 /* If this is a paged skb, make sure we pull up
93 * whatever data we need to look at. */
94 len = skb->len - sizeof(struct udphdr);
95 if (!pskb_may_pull(skb, len: sizeof(struct udphdr) + min(len, 8)))
96 return 1;
97
98 /* Now we can get the pointers */
99 uh = udp_hdr(skb);
100 udpdata = (__u8 *)uh + sizeof(struct udphdr);
101 udpdata32 = (__be32 *)udpdata;
102
103 switch (encap_type) {
104 default:
105 case UDP_ENCAP_ESPINUDP:
106 /* Check if this is a keepalive packet. If so, eat it. */
107 if (len == 1 && udpdata[0] == 0xff) {
108 return -EINVAL;
109 } else if (len > sizeof(struct ip_esp_hdr) && udpdata32[0] != 0) {
110 /* ESP Packet without Non-ESP header */
111 len = sizeof(struct udphdr);
112 } else
113 /* Must be an IKE packet.. pass it through */
114 return 1;
115 break;
116 }
117
118 /* At this point we are sure that this is an ESPinUDP packet,
119 * so we need to remove 'len' bytes from the packet (the UDP
120 * header and optional ESP marker bytes) and then modify the
121 * protocol to ESP, and then call into the transform receiver.
122 */
123 if (skb_unclone(skb, GFP_ATOMIC))
124 return -EINVAL;
125
126 /* Now we can update and verify the packet length... */
127 ip6h = ipv6_hdr(skb);
128 ip6h->payload_len = htons(ntohs(ip6h->payload_len) - len);
129 if (skb->len < ip6hlen + len) {
130 /* packet is too small!?! */
131 return -EINVAL;
132 }
133
134 /* pull the data buffer up to the ESP header and set the
135 * transport header to point to ESP. Keep UDP on the stack
136 * for later.
137 */
138 if (pull) {
139 __skb_pull(skb, len);
140 skb_reset_transport_header(skb);
141 } else {
142 skb_set_transport_header(skb, offset: len);
143 }
144
145 /* process ESP */
146 return 0;
147}
148
149/* If it's a keepalive packet, then just eat it.
150 * If it's an encapsulated packet, then pass it to the
151 * IPsec xfrm input.
152 * Returns 0 if skb passed to xfrm or was dropped.
153 * Returns >0 if skb should be passed to UDP.
154 * Returns <0 if skb should be resubmitted (-ret is protocol)
155 */
156int xfrm6_udp_encap_rcv(struct sock *sk, struct sk_buff *skb)
157{
158 int ret;
159
160 if (skb->protocol == htons(ETH_P_IP))
161 return xfrm4_udp_encap_rcv(sk, skb);
162
163 ret = __xfrm6_udp_encap_rcv(sk, skb, pull: true);
164 if (!ret)
165 return xfrm6_rcv_encap(skb, IPPROTO_ESP, spi: 0,
166 udp_sk(sk)->encap_type);
167
168 if (ret < 0) {
169 kfree_skb(skb);
170 return 0;
171 }
172
173 return ret;
174}
175
176struct sk_buff *xfrm6_gro_udp_encap_rcv(struct sock *sk, struct list_head *head,
177 struct sk_buff *skb)
178{
179 int offset = skb_gro_offset(skb);
180 const struct net_offload *ops;
181 struct sk_buff *pp = NULL;
182 int len, dlen;
183 __u8 *udpdata;
184 __be32 *udpdata32;
185
186 if (skb->protocol == htons(ETH_P_IP))
187 return xfrm4_gro_udp_encap_rcv(sk, head, skb);
188
189 len = skb->len - offset;
190 dlen = offset + min(len, 8);
191 udpdata = skb_gro_header(skb, hlen: dlen, offset);
192 udpdata32 = (__be32 *)udpdata;
193 if (unlikely(!udpdata))
194 return NULL;
195
196 rcu_read_lock();
197 ops = rcu_dereference(inet6_offloads[IPPROTO_ESP]);
198 if (!ops || !ops->callbacks.gro_receive)
199 goto out;
200
201 /* check if it is a keepalive or IKE packet */
202 if (len <= sizeof(struct ip_esp_hdr) || udpdata32[0] == 0)
203 goto out;
204
205 /* set the transport header to ESP */
206 skb_set_transport_header(skb, offset);
207
208 NAPI_GRO_CB(skb)->proto = IPPROTO_UDP;
209
210 pp = call_gro_receive(cb: ops->callbacks.gro_receive, head, skb);
211 rcu_read_unlock();
212
213 return pp;
214
215out:
216 rcu_read_unlock();
217 NAPI_GRO_CB(skb)->same_flow = 0;
218 NAPI_GRO_CB(skb)->flush = 1;
219
220 return NULL;
221}
222
223int xfrm6_rcv_tnl(struct sk_buff *skb, struct ip6_tnl *t)
224{
225 return xfrm6_rcv_spi(skb, skb_network_header(skb)[IP6CB(skb)->nhoff],
226 0, t);
227}
228EXPORT_SYMBOL(xfrm6_rcv_tnl);
229
230int xfrm6_rcv(struct sk_buff *skb)
231{
232 return xfrm6_rcv_tnl(skb, NULL);
233}
234EXPORT_SYMBOL(xfrm6_rcv);
235int xfrm6_input_addr(struct sk_buff *skb, xfrm_address_t *daddr,
236 xfrm_address_t *saddr, u8 proto)
237{
238 struct net *net = dev_net(dev: skb->dev);
239 struct xfrm_state *x = NULL;
240 struct sec_path *sp;
241 int i = 0;
242
243 sp = secpath_set(skb);
244 if (!sp) {
245 XFRM_INC_STATS(net, LINUX_MIB_XFRMINERROR);
246 goto drop;
247 }
248
249 if (1 + sp->len == XFRM_MAX_DEPTH) {
250 XFRM_INC_STATS(net, LINUX_MIB_XFRMINBUFFERERROR);
251 goto drop;
252 }
253
254 for (i = 0; i < 3; i++) {
255 xfrm_address_t *dst, *src;
256
257 switch (i) {
258 case 0:
259 dst = daddr;
260 src = saddr;
261 break;
262 case 1:
263 /* lookup state with wild-card source address */
264 dst = daddr;
265 src = (xfrm_address_t *)&in6addr_any;
266 break;
267 default:
268 /* lookup state with wild-card addresses */
269 dst = (xfrm_address_t *)&in6addr_any;
270 src = (xfrm_address_t *)&in6addr_any;
271 break;
272 }
273
274 x = xfrm_state_lookup_byaddr(net, mark: skb->mark, daddr: dst, saddr: src, proto, AF_INET6);
275 if (!x)
276 continue;
277
278 if (unlikely(x->dir && x->dir != XFRM_SA_DIR_IN)) {
279 XFRM_INC_STATS(net, LINUX_MIB_XFRMINSTATEDIRERROR);
280 xfrm_state_put(x);
281 x = NULL;
282 continue;
283 }
284
285 spin_lock(lock: &x->lock);
286
287 if ((!i || (x->props.flags & XFRM_STATE_WILDRECV)) &&
288 likely(x->km.state == XFRM_STATE_VALID) &&
289 !xfrm_state_check_expire(x)) {
290 spin_unlock(lock: &x->lock);
291 if (x->type->input(x, skb) > 0) {
292 /* found a valid state */
293 break;
294 }
295 } else
296 spin_unlock(lock: &x->lock);
297
298 xfrm_state_put(x);
299 x = NULL;
300 }
301
302 if (!x) {
303 XFRM_INC_STATS(net, LINUX_MIB_XFRMINNOSTATES);
304 xfrm_audit_state_notfound_simple(skb, AF_INET6);
305 goto drop;
306 }
307
308 sp->xvec[sp->len++] = x;
309
310 spin_lock(lock: &x->lock);
311
312 x->curlft.bytes += skb->len;
313 x->curlft.packets++;
314
315 spin_unlock(lock: &x->lock);
316
317 return 1;
318
319drop:
320 return -1;
321}
322EXPORT_SYMBOL(xfrm6_input_addr);
323