xref: /linux/net/ipv6/xfrm6_input.c (revision 056a5087d87ead77dedbe9cf5bde53b7cd4b4651) 
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 
22 int 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 }
30 EXPORT_SYMBOL(xfrm6_rcv_spi);
31 
32 static 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 
43 int xfrm6_transport_finish(struct sk_buff *skb, int async)
44 {
45 	struct xfrm_offload *xo = xfrm_offload(skb);
46 	struct net_device *dev = skb->dev;
47 	int nhlen = -skb_network_offset(skb);
48 
49 	skb_network_header(skb)[IP6CB(skb)->nhoff] =
50 		XFRM_MODE_SKB_CB(skb)->protocol;
51 
52 #ifndef CONFIG_NETFILTER
53 	if (!async)
54 		return 1;
55 #endif
56 
57 	__skb_push(skb, nhlen);
58 	ipv6_hdr(skb)->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
59 	skb_postpush_rcsum(skb, skb_network_header(skb), nhlen);
60 
61 	if (xo && (xo->flags & XFRM_GRO)) {
62 		/* The full l2 header needs to be preserved so that re-injecting the packet at l2
63 		 * works correctly in the presence of vlan tags.
64 		 */
65 		skb_mac_header_rebuild_full(skb, xo->orig_mac_len);
66 		skb_reset_network_header(skb);
67 		skb_reset_transport_header(skb);
68 		return 0;
69 	}
70 
71 	NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING,
72 		dev_net(dev), NULL, skb, dev, NULL,
73 		xfrm6_transport_finish2);
74 	return 0;
75 }
76 
77 static int __xfrm6_udp_encap_rcv(struct sock *sk, struct sk_buff *skb, bool pull)
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 	__u8 *udpdata;
85 	__be32 *udpdata32;
86 	u16 encap_type;
87 
88 	encap_type = READ_ONCE(up->encap_type);
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 			return -EINVAL;
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 	}
118 
119 	/* At this point we are sure that this is an ESPinUDP packet,
120 	 * so we need to remove 'len' bytes from the packet (the UDP
121 	 * header and optional ESP marker bytes) and then modify the
122 	 * protocol to ESP, and then call into the transform receiver.
123 	 */
124 	if (skb_unclone(skb, GFP_ATOMIC))
125 		return -EINVAL;
126 
127 	/* Now we can update and verify the packet length... */
128 	ip6h = ipv6_hdr(skb);
129 	ip6h->payload_len = htons(ntohs(ip6h->payload_len) - len);
130 	if (skb->len < ip6hlen + len) {
131 		/* packet is too small!?! */
132 		return -EINVAL;
133 	}
134 
135 	/* pull the data buffer up to the ESP header and set the
136 	 * transport header to point to ESP.  Keep UDP on the stack
137 	 * for later.
138 	 */
139 	if (pull) {
140 		__skb_pull(skb, len);
141 		skb_reset_transport_header(skb);
142 	} else {
143 		skb_set_transport_header(skb, len);
144 	}
145 
146 	/* process ESP */
147 	return 0;
148 }
149 
150 /* If it's a keepalive packet, then just eat it.
151  * If it's an encapsulated packet, then pass it to the
152  * IPsec xfrm input.
153  * Returns 0 if skb passed to xfrm or was dropped.
154  * Returns >0 if skb should be passed to UDP.
155  * Returns <0 if skb should be resubmitted (-ret is protocol)
156  */
157 int xfrm6_udp_encap_rcv(struct sock *sk, struct sk_buff *skb)
158 {
159 	int ret;
160 
161 	if (skb->protocol == htons(ETH_P_IP))
162 		return xfrm4_udp_encap_rcv(sk, skb);
163 
164 	ret = __xfrm6_udp_encap_rcv(sk, skb, true);
165 	if (!ret)
166 		return xfrm6_rcv_encap(skb, IPPROTO_ESP, 0,
167 				       udp_sk(sk)->encap_type);
168 
169 	if (ret < 0) {
170 		kfree_skb(skb);
171 		return 0;
172 	}
173 
174 	return ret;
175 }
176 
177 struct sk_buff *xfrm6_gro_udp_encap_rcv(struct sock *sk, struct list_head *head,
178 					struct sk_buff *skb)
179 {
180 	int offset = skb_gro_offset(skb);
181 	const struct net_offload *ops;
182 	struct sk_buff *pp = NULL;
183 	int len, dlen;
184 	__u8 *udpdata;
185 	__be32 *udpdata32;
186 
187 	if (skb->protocol == htons(ETH_P_IP))
188 		return xfrm4_gro_udp_encap_rcv(sk, head, skb);
189 
190 	len = skb->len - offset;
191 	dlen = offset + min(len, 8);
192 	udpdata = skb_gro_header(skb, dlen, offset);
193 	udpdata32 = (__be32 *)udpdata;
194 	if (unlikely(!udpdata))
195 		return NULL;
196 
197 	rcu_read_lock();
198 	ops = rcu_dereference(inet6_offloads[IPPROTO_ESP]);
199 	if (!ops || !ops->callbacks.gro_receive)
200 		goto out;
201 
202 	/* check if it is a keepalive or IKE packet */
203 	if (len <= sizeof(struct ip_esp_hdr) || udpdata32[0] == 0)
204 		goto out;
205 
206 	/* set the transport header to ESP */
207 	skb_set_transport_header(skb, offset);
208 
209 	NAPI_GRO_CB(skb)->proto = IPPROTO_UDP;
210 
211 	pp = call_gro_receive(ops->callbacks.gro_receive, head, skb);
212 	rcu_read_unlock();
213 
214 	return pp;
215 
216 out:
217 	rcu_read_unlock();
218 	NAPI_GRO_CB(skb)->same_flow = 0;
219 	NAPI_GRO_CB(skb)->flush = 1;
220 
221 	return NULL;
222 }
223 
224 int xfrm6_rcv_tnl(struct sk_buff *skb, struct ip6_tnl *t)
225 {
226 	return xfrm6_rcv_spi(skb, skb_network_header(skb)[IP6CB(skb)->nhoff],
227 			     0, t);
228 }
229 EXPORT_SYMBOL(xfrm6_rcv_tnl);
230 
231 int xfrm6_rcv(struct sk_buff *skb)
232 {
233 	return xfrm6_rcv_tnl(skb, NULL);
234 }
235 EXPORT_SYMBOL(xfrm6_rcv);
236 int xfrm6_input_addr(struct sk_buff *skb, xfrm_address_t *daddr,
237 		     xfrm_address_t *saddr, u8 proto)
238 {
239 	struct net *net = dev_net(skb->dev);
240 	struct xfrm_state *x = NULL;
241 	struct sec_path *sp;
242 	int i = 0;
243 
244 	sp = secpath_set(skb);
245 	if (!sp) {
246 		XFRM_INC_STATS(net, LINUX_MIB_XFRMINERROR);
247 		goto drop;
248 	}
249 
250 	if (1 + sp->len == XFRM_MAX_DEPTH) {
251 		XFRM_INC_STATS(net, LINUX_MIB_XFRMINBUFFERERROR);
252 		goto drop;
253 	}
254 
255 	for (i = 0; i < 3; i++) {
256 		xfrm_address_t *dst, *src;
257 
258 		switch (i) {
259 		case 0:
260 			dst = daddr;
261 			src = saddr;
262 			break;
263 		case 1:
264 			/* lookup state with wild-card source address */
265 			dst = daddr;
266 			src = (xfrm_address_t *)&in6addr_any;
267 			break;
268 		default:
269 			/* lookup state with wild-card addresses */
270 			dst = (xfrm_address_t *)&in6addr_any;
271 			src = (xfrm_address_t *)&in6addr_any;
272 			break;
273 		}
274 
275 		x = xfrm_state_lookup_byaddr(net, skb->mark, dst, src, proto, AF_INET6);
276 		if (!x)
277 			continue;
278 
279 		if (unlikely(x->dir && x->dir != XFRM_SA_DIR_IN)) {
280 			XFRM_INC_STATS(net, LINUX_MIB_XFRMINSTATEDIRERROR);
281 			xfrm_state_put(x);
282 			x = NULL;
283 			continue;
284 		}
285 
286 		spin_lock(&x->lock);
287 
288 		if ((!i || (x->props.flags & XFRM_STATE_WILDRECV)) &&
289 		    likely(x->km.state == XFRM_STATE_VALID) &&
290 		    !xfrm_state_check_expire(x)) {
291 			spin_unlock(&x->lock);
292 			if (x->type->input(x, skb) > 0) {
293 				/* found a valid state */
294 				break;
295 			}
296 		} else
297 			spin_unlock(&x->lock);
298 
299 		xfrm_state_put(x);
300 		x = NULL;
301 	}
302 
303 	if (!x) {
304 		XFRM_INC_STATS(net, LINUX_MIB_XFRMINNOSTATES);
305 		xfrm_audit_state_notfound_simple(skb, AF_INET6);
306 		goto drop;
307 	}
308 
309 	sp->xvec[sp->len++] = x;
310 
311 	spin_lock(&x->lock);
312 
313 	x->curlft.bytes += skb->len;
314 	x->curlft.packets++;
315 
316 	spin_unlock(&x->lock);
317 
318 	return 1;
319 
320 drop:
321 	return -1;
322 }
323 EXPORT_SYMBOL(xfrm6_input_addr);
324