xref: /linux/net/ipv6/xfrm6_input.c (revision 5ea5880764cbb164afb17a62e76ca75dc371409d) 
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 	if (async)
75 		dev_put(dev);
76 	return 0;
77 }
78 
79 static int __xfrm6_udp_encap_rcv(struct sock *sk, struct sk_buff *skb, bool pull)
80 {
81 	struct udp_sock *up = udp_sk(sk);
82 	struct udphdr *uh;
83 	struct ipv6hdr *ip6h;
84 	int len;
85 	int ip6hlen = sizeof(struct ipv6hdr);
86 	__u8 *udpdata;
87 	__be32 *udpdata32;
88 	u16 encap_type;
89 
90 	encap_type = READ_ONCE(up->encap_type);
91 	/* if this is not encapsulated socket, then just return now */
92 	if (!encap_type)
93 		return 1;
94 
95 	/* If this is a paged skb, make sure we pull up
96 	 * whatever data we need to look at. */
97 	len = skb->len - sizeof(struct udphdr);
98 	if (!pskb_may_pull(skb, sizeof(struct udphdr) + min(len, 8)))
99 		return 1;
100 
101 	/* Now we can get the pointers */
102 	uh = udp_hdr(skb);
103 	udpdata = (__u8 *)uh + sizeof(struct udphdr);
104 	udpdata32 = (__be32 *)udpdata;
105 
106 	switch (encap_type) {
107 	default:
108 	case UDP_ENCAP_ESPINUDP:
109 		/* Check if this is a keepalive packet.  If so, eat it. */
110 		if (len == 1 && udpdata[0] == 0xff) {
111 			return -EINVAL;
112 		} else if (len > sizeof(struct ip_esp_hdr) && udpdata32[0] != 0) {
113 			/* ESP Packet without Non-ESP header */
114 			len = sizeof(struct udphdr);
115 		} else
116 			/* Must be an IKE packet.. pass it through */
117 			return 1;
118 		break;
119 	}
120 
121 	/* At this point we are sure that this is an ESPinUDP packet,
122 	 * so we need to remove 'len' bytes from the packet (the UDP
123 	 * header and optional ESP marker bytes) and then modify the
124 	 * protocol to ESP, and then call into the transform receiver.
125 	 */
126 	if (skb_unclone(skb, GFP_ATOMIC))
127 		return -EINVAL;
128 
129 	/* Now we can update and verify the packet length... */
130 	ip6h = ipv6_hdr(skb);
131 	ip6h->payload_len = htons(ntohs(ip6h->payload_len) - len);
132 	if (skb->len < ip6hlen + len) {
133 		/* packet is too small!?! */
134 		return -EINVAL;
135 	}
136 
137 	/* pull the data buffer up to the ESP header and set the
138 	 * transport header to point to ESP.  Keep UDP on the stack
139 	 * for later.
140 	 */
141 	if (pull) {
142 		__skb_pull(skb, len);
143 		skb_reset_transport_header(skb);
144 	} else {
145 		skb_set_transport_header(skb, len);
146 	}
147 
148 	/* process ESP */
149 	return 0;
150 }
151 
152 /* If it's a keepalive packet, then just eat it.
153  * If it's an encapsulated packet, then pass it to the
154  * IPsec xfrm input.
155  * Returns 0 if skb passed to xfrm or was dropped.
156  * Returns >0 if skb should be passed to UDP.
157  * Returns <0 if skb should be resubmitted (-ret is protocol)
158  */
159 int xfrm6_udp_encap_rcv(struct sock *sk, struct sk_buff *skb)
160 {
161 	int ret;
162 
163 	if (skb->protocol == htons(ETH_P_IP))
164 		return xfrm4_udp_encap_rcv(sk, skb);
165 
166 	ret = __xfrm6_udp_encap_rcv(sk, skb, true);
167 	if (!ret)
168 		return xfrm6_rcv_encap(skb, IPPROTO_ESP, 0,
169 				       udp_sk(sk)->encap_type);
170 
171 	if (ret < 0) {
172 		kfree_skb(skb);
173 		return 0;
174 	}
175 
176 	return ret;
177 }
178 
179 struct sk_buff *xfrm6_gro_udp_encap_rcv(struct sock *sk, struct list_head *head,
180 					struct sk_buff *skb)
181 {
182 	int offset = skb_gro_offset(skb);
183 	const struct net_offload *ops;
184 	struct sk_buff *pp = NULL;
185 	int len, dlen;
186 	__u8 *udpdata;
187 	__be32 *udpdata32;
188 
189 	if (skb->protocol == htons(ETH_P_IP))
190 		return xfrm4_gro_udp_encap_rcv(sk, head, skb);
191 
192 	len = skb->len - offset;
193 	dlen = offset + min(len, 8);
194 	udpdata = skb_gro_header(skb, dlen, offset);
195 	udpdata32 = (__be32 *)udpdata;
196 	if (unlikely(!udpdata))
197 		return NULL;
198 
199 	rcu_read_lock();
200 	ops = rcu_dereference(inet6_offloads[IPPROTO_ESP]);
201 	if (!ops || !ops->callbacks.gro_receive)
202 		goto out;
203 
204 	/* check if it is a keepalive or IKE packet */
205 	if (len <= sizeof(struct ip_esp_hdr) || udpdata32[0] == 0)
206 		goto out;
207 
208 	/* set the transport header to ESP */
209 	skb_set_transport_header(skb, offset);
210 
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 
218 out:
219 	rcu_read_unlock();
220 	NAPI_GRO_CB(skb)->same_flow = 0;
221 	NAPI_GRO_CB(skb)->flush = 1;
222 
223 	return NULL;
224 }
225 
226 int xfrm6_rcv_tnl(struct sk_buff *skb, struct ip6_tnl *t)
227 {
228 	return xfrm6_rcv_spi(skb, skb_network_header(skb)[IP6CB(skb)->nhoff],
229 			     0, t);
230 }
231 EXPORT_SYMBOL(xfrm6_rcv_tnl);
232 
233 int xfrm6_rcv(struct sk_buff *skb)
234 {
235 	return xfrm6_rcv_tnl(skb, NULL);
236 }
237 EXPORT_SYMBOL(xfrm6_rcv);
238 int xfrm6_input_addr(struct sk_buff *skb, xfrm_address_t *daddr,
239 		     xfrm_address_t *saddr, u8 proto)
240 {
241 	struct net *net = dev_net(skb->dev);
242 	struct xfrm_state *x = NULL;
243 	struct sec_path *sp;
244 	int i = 0;
245 
246 	sp = secpath_set(skb);
247 	if (!sp) {
248 		XFRM_INC_STATS(net, LINUX_MIB_XFRMINERROR);
249 		goto drop;
250 	}
251 
252 	if (1 + sp->len == XFRM_MAX_DEPTH) {
253 		XFRM_INC_STATS(net, LINUX_MIB_XFRMINBUFFERERROR);
254 		goto drop;
255 	}
256 
257 	for (i = 0; i < 3; i++) {
258 		xfrm_address_t *dst, *src;
259 
260 		switch (i) {
261 		case 0:
262 			dst = daddr;
263 			src = saddr;
264 			break;
265 		case 1:
266 			/* lookup state with wild-card source address */
267 			dst = daddr;
268 			src = (xfrm_address_t *)&in6addr_any;
269 			break;
270 		default:
271 			/* lookup state with wild-card addresses */
272 			dst = (xfrm_address_t *)&in6addr_any;
273 			src = (xfrm_address_t *)&in6addr_any;
274 			break;
275 		}
276 
277 		x = xfrm_state_lookup_byaddr(net, skb->mark, dst, src, proto, AF_INET6);
278 		if (!x)
279 			continue;
280 
281 		if (unlikely(x->dir && x->dir != XFRM_SA_DIR_IN)) {
282 			XFRM_INC_STATS(net, LINUX_MIB_XFRMINSTATEDIRERROR);
283 			xfrm_state_put(x);
284 			x = NULL;
285 			continue;
286 		}
287 
288 		spin_lock(&x->lock);
289 
290 		if ((!i || (x->props.flags & XFRM_STATE_WILDRECV)) &&
291 		    likely(x->km.state == XFRM_STATE_VALID) &&
292 		    !xfrm_state_check_expire(x)) {
293 			spin_unlock(&x->lock);
294 			if (x->type->input(x, skb) > 0) {
295 				/* found a valid state */
296 				break;
297 			}
298 		} else
299 			spin_unlock(&x->lock);
300 
301 		xfrm_state_put(x);
302 		x = NULL;
303 	}
304 
305 	if (!x) {
306 		XFRM_INC_STATS(net, LINUX_MIB_XFRMINNOSTATES);
307 		xfrm_audit_state_notfound_simple(skb, AF_INET6);
308 		goto drop;
309 	}
310 
311 	sp->xvec[sp->len++] = x;
312 
313 	spin_lock(&x->lock);
314 
315 	x->curlft.bytes += skb->len;
316 	x->curlft.packets++;
317 
318 	spin_unlock(&x->lock);
319 
320 	return 1;
321 
322 drop:
323 	return -1;
324 }
325 EXPORT_SYMBOL(xfrm6_input_addr);
326