xref: /linux/net/ipv6/xfrm6_input.c (revision 22c55fb9eb92395d999b8404d73e58540d11bdd8) 
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 	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 		/* 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, xo->orig_mac_len);
65 		skb_reset_network_header(skb);
66 		skb_reset_transport_header(skb);
67 		return 0;
68 	}
69 
70 	NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING,
71 		dev_net(skb->dev), NULL, skb, skb->dev, NULL,
72 		xfrm6_transport_finish2);
73 	return 0;
74 }
75 
76 static 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, 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, 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  */
156 int 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, true);
164 	if (!ret)
165 		return xfrm6_rcv_encap(skb, IPPROTO_ESP, 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 
176 struct 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, 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(ops->callbacks.gro_receive, head, skb);
211 	rcu_read_unlock();
212 
213 	return pp;
214 
215 out:
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 
223 int 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 }
228 EXPORT_SYMBOL(xfrm6_rcv_tnl);
229 
230 int xfrm6_rcv(struct sk_buff *skb)
231 {
232 	return xfrm6_rcv_tnl(skb, NULL);
233 }
234 EXPORT_SYMBOL(xfrm6_rcv);
235 int 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(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, skb->mark, dst, 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(&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(&x->lock);
291 			if (x->type->input(x, skb) > 0) {
292 				/* found a valid state */
293 				break;
294 			}
295 		} else
296 			spin_unlock(&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(&x->lock);
311 
312 	x->curlft.bytes += skb->len;
313 	x->curlft.packets++;
314 
315 	spin_unlock(&x->lock);
316 
317 	return 1;
318 
319 drop:
320 	return -1;
321 }
322 EXPORT_SYMBOL(xfrm6_input_addr);
323