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, 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, 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, nhlen);
57	ipv6_hdr(skb)->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
58	skb_postpush_rcsum(skb, skb_network_header(skb), nhlen);
59
60	if (xo && (xo->flags & XFRM_GRO)) {
61		skb_mac_header_rebuild(skb);
62		skb_reset_transport_header(skb);
63		return 0;
64	}
65
66	NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING,
67		dev_net(skb->dev), NULL, skb, skb->dev, NULL,
68		xfrm6_transport_finish2);
69	return 0;
70}
71
72static int __xfrm6_udp_encap_rcv(struct sock *sk, struct sk_buff *skb, bool pull)
73{
74	struct udp_sock *up = udp_sk(sk);
75	struct udphdr *uh;
76	struct ipv6hdr *ip6h;
77	int len;
78	int ip6hlen = sizeof(struct ipv6hdr);
79	__u8 *udpdata;
80	__be32 *udpdata32;
81	u16 encap_type;
82
83	encap_type = READ_ONCE(up->encap_type);
84	/* if this is not encapsulated socket, then just return now */
85	if (!encap_type)
86		return 1;
87
88	/* If this is a paged skb, make sure we pull up
89	 * whatever data we need to look at. */
90	len = skb->len - sizeof(struct udphdr);
91	if (!pskb_may_pull(skb, sizeof(struct udphdr) + min(len, 8)))
92		return 1;
93
94	/* Now we can get the pointers */
95	uh = udp_hdr(skb);
96	udpdata = (__u8 *)uh + sizeof(struct udphdr);
97	udpdata32 = (__be32 *)udpdata;
98
99	switch (encap_type) {
100	default:
101	case UDP_ENCAP_ESPINUDP:
102		/* Check if this is a keepalive packet.  If so, eat it. */
103		if (len == 1 && udpdata[0] == 0xff) {
104			return -EINVAL;
105		} else if (len > sizeof(struct ip_esp_hdr) && udpdata32[0] != 0) {
106			/* ESP Packet without Non-ESP header */
107			len = sizeof(struct udphdr);
108		} else
109			/* Must be an IKE packet.. pass it through */
110			return 1;
111		break;
112	case UDP_ENCAP_ESPINUDP_NON_IKE:
113		/* Check if this is a keepalive packet.  If so, eat it. */
114		if (len == 1 && udpdata[0] == 0xff) {
115			return -EINVAL;
116		} else if (len > 2 * sizeof(u32) + sizeof(struct ip_esp_hdr) &&
117			   udpdata32[0] == 0 && udpdata32[1] == 0) {
118
119			/* ESP Packet with Non-IKE marker */
120			len = sizeof(struct udphdr) + 2 * sizeof(u32);
121		} else
122			/* Must be an IKE packet.. pass it through */
123			return 1;
124		break;
125	}
126
127	/* At this point we are sure that this is an ESPinUDP packet,
128	 * so we need to remove 'len' bytes from the packet (the UDP
129	 * header and optional ESP marker bytes) and then modify the
130	 * protocol to ESP, and then call into the transform receiver.
131	 */
132	if (skb_unclone(skb, GFP_ATOMIC))
133		return -EINVAL;
134
135	/* Now we can update and verify the packet length... */
136	ip6h = ipv6_hdr(skb);
137	ip6h->payload_len = htons(ntohs(ip6h->payload_len) - len);
138	if (skb->len < ip6hlen + len) {
139		/* packet is too small!?! */
140		return -EINVAL;
141	}
142
143	/* pull the data buffer up to the ESP header and set the
144	 * transport header to point to ESP.  Keep UDP on the stack
145	 * for later.
146	 */
147	if (pull) {
148		__skb_pull(skb, len);
149		skb_reset_transport_header(skb);
150	} else {
151		skb_set_transport_header(skb, len);
152	}
153
154	/* process ESP */
155	return 0;
156}
157
158/* If it's a keepalive packet, then just eat it.
159 * If it's an encapsulated packet, then pass it to the
160 * IPsec xfrm input.
161 * Returns 0 if skb passed to xfrm or was dropped.
162 * Returns >0 if skb should be passed to UDP.
163 * Returns <0 if skb should be resubmitted (-ret is protocol)
164 */
165int xfrm6_udp_encap_rcv(struct sock *sk, struct sk_buff *skb)
166{
167	int ret;
168
169	if (skb->protocol == htons(ETH_P_IP))
170		return xfrm4_udp_encap_rcv(sk, skb);
171
172	ret = __xfrm6_udp_encap_rcv(sk, skb, true);
173	if (!ret)
174		return xfrm6_rcv_encap(skb, IPPROTO_ESP, 0,
175				       udp_sk(sk)->encap_type);
176
177	if (ret < 0) {
178		kfree_skb(skb);
179		return 0;
180	}
181
182	return ret;
183}
184
185struct sk_buff *xfrm6_gro_udp_encap_rcv(struct sock *sk, struct list_head *head,
186					struct sk_buff *skb)
187{
188	int offset = skb_gro_offset(skb);
189	const struct net_offload *ops;
190	struct sk_buff *pp = NULL;
191	int ret;
192
193	if (skb->protocol == htons(ETH_P_IP))
194		return xfrm4_gro_udp_encap_rcv(sk, head, skb);
195
196	offset = offset - sizeof(struct udphdr);
197
198	if (!pskb_pull(skb, offset))
199		return NULL;
200
201	rcu_read_lock();
202	ops = rcu_dereference(inet6_offloads[IPPROTO_ESP]);
203	if (!ops || !ops->callbacks.gro_receive)
204		goto out;
205
206	ret = __xfrm6_udp_encap_rcv(sk, skb, false);
207	if (ret)
208		goto out;
209
210	skb_push(skb, offset);
211	NAPI_GRO_CB(skb)->proto = IPPROTO_UDP;
212
213	pp = call_gro_receive(ops->callbacks.gro_receive, head, skb);
214	rcu_read_unlock();
215
216	return pp;
217
218out:
219	rcu_read_unlock();
220	skb_push(skb, offset);
221	NAPI_GRO_CB(skb)->same_flow = 0;
222	NAPI_GRO_CB(skb)->flush = 1;
223
224	return NULL;
225}
226
227int xfrm6_rcv_tnl(struct sk_buff *skb, struct ip6_tnl *t)
228{
229	return xfrm6_rcv_spi(skb, skb_network_header(skb)[IP6CB(skb)->nhoff],
230			     0, t);
231}
232EXPORT_SYMBOL(xfrm6_rcv_tnl);
233
234int xfrm6_rcv(struct sk_buff *skb)
235{
236	return xfrm6_rcv_tnl(skb, NULL);
237}
238EXPORT_SYMBOL(xfrm6_rcv);
239int xfrm6_input_addr(struct sk_buff *skb, xfrm_address_t *daddr,
240		     xfrm_address_t *saddr, u8 proto)
241{
242	struct net *net = dev_net(skb->dev);
243	struct xfrm_state *x = NULL;
244	struct sec_path *sp;
245	int i = 0;
246
247	sp = secpath_set(skb);
248	if (!sp) {
249		XFRM_INC_STATS(net, LINUX_MIB_XFRMINERROR);
250		goto drop;
251	}
252
253	if (1 + sp->len == XFRM_MAX_DEPTH) {
254		XFRM_INC_STATS(net, LINUX_MIB_XFRMINBUFFERERROR);
255		goto drop;
256	}
257
258	for (i = 0; i < 3; i++) {
259		xfrm_address_t *dst, *src;
260
261		switch (i) {
262		case 0:
263			dst = daddr;
264			src = saddr;
265			break;
266		case 1:
267			/* lookup state with wild-card source address */
268			dst = daddr;
269			src = (xfrm_address_t *)&in6addr_any;
270			break;
271		default:
272			/* lookup state with wild-card addresses */
273			dst = (xfrm_address_t *)&in6addr_any;
274			src = (xfrm_address_t *)&in6addr_any;
275			break;
276		}
277
278		x = xfrm_state_lookup_byaddr(net, skb->mark, dst, src, proto, AF_INET6);
279		if (!x)
280			continue;
281
282		spin_lock(&x->lock);
283
284		if ((!i || (x->props.flags & XFRM_STATE_WILDRECV)) &&
285		    likely(x->km.state == XFRM_STATE_VALID) &&
286		    !xfrm_state_check_expire(x)) {
287			spin_unlock(&x->lock);
288			if (x->type->input(x, skb) > 0) {
289				/* found a valid state */
290				break;
291			}
292		} else
293			spin_unlock(&x->lock);
294
295		xfrm_state_put(x);
296		x = NULL;
297	}
298
299	if (!x) {
300		XFRM_INC_STATS(net, LINUX_MIB_XFRMINNOSTATES);
301		xfrm_audit_state_notfound_simple(skb, AF_INET6);
302		goto drop;
303	}
304
305	sp->xvec[sp->len++] = x;
306
307	spin_lock(&x->lock);
308
309	x->curlft.bytes += skb->len;
310	x->curlft.packets++;
311
312	spin_unlock(&x->lock);
313
314	return 1;
315
316drop:
317	return -1;
318}
319EXPORT_SYMBOL(xfrm6_input_addr);
320