xref: /openbmc/linux/net/ipv6/xfrm6_input.c (revision 5ffd8c73)
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 
20 int xfrm6_rcv_spi(struct sk_buff *skb, int nexthdr, __be32 spi,
21 		  struct ip6_tnl *t)
22 {
23 	XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip6 = t;
24 	XFRM_SPI_SKB_CB(skb)->family = AF_INET6;
25 	XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct ipv6hdr, daddr);
26 	return xfrm_input(skb, nexthdr, spi, 0);
27 }
28 EXPORT_SYMBOL(xfrm6_rcv_spi);
29 
30 static int xfrm6_transport_finish2(struct net *net, struct sock *sk,
31 				   struct sk_buff *skb)
32 {
33 	if (xfrm_trans_queue(skb, ip6_rcv_finish)) {
34 		kfree_skb(skb);
35 		return NET_RX_DROP;
36 	}
37 
38 	return 0;
39 }
40 
41 int xfrm6_transport_finish(struct sk_buff *skb, int async)
42 {
43 	struct xfrm_offload *xo = xfrm_offload(skb);
44 	int nhlen = skb->data - skb_network_header(skb);
45 
46 	skb_network_header(skb)[IP6CB(skb)->nhoff] =
47 		XFRM_MODE_SKB_CB(skb)->protocol;
48 
49 #ifndef CONFIG_NETFILTER
50 	if (!async)
51 		return 1;
52 #endif
53 
54 	__skb_push(skb, nhlen);
55 	ipv6_hdr(skb)->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
56 	skb_postpush_rcsum(skb, skb_network_header(skb), nhlen);
57 
58 	if (xo && (xo->flags & XFRM_GRO)) {
59 		skb_mac_header_rebuild(skb);
60 		skb_reset_transport_header(skb);
61 		return 0;
62 	}
63 
64 	NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING,
65 		dev_net(skb->dev), NULL, skb, skb->dev, NULL,
66 		xfrm6_transport_finish2);
67 	return 0;
68 }
69 
70 /* If it's a keepalive packet, then just eat it.
71  * If it's an encapsulated packet, then pass it to the
72  * IPsec xfrm input.
73  * Returns 0 if skb passed to xfrm or was dropped.
74  * Returns >0 if skb should be passed to UDP.
75  * Returns <0 if skb should be resubmitted (-ret is protocol)
76  */
77 int xfrm6_udp_encap_rcv(struct sock *sk, struct sk_buff *skb)
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 	if (skb->protocol == htons(ETH_P_IP))
89 		return xfrm4_udp_encap_rcv(sk, skb);
90 
91 	encap_type = READ_ONCE(up->encap_type);
92 	/* if this is not encapsulated socket, then just return now */
93 	if (!encap_type)
94 		return 1;
95 
96 	/* If this is a paged skb, make sure we pull up
97 	 * whatever data we need to look at. */
98 	len = skb->len - sizeof(struct udphdr);
99 	if (!pskb_may_pull(skb, sizeof(struct udphdr) + min(len, 8)))
100 		return 1;
101 
102 	/* Now we can get the pointers */
103 	uh = udp_hdr(skb);
104 	udpdata = (__u8 *)uh + sizeof(struct udphdr);
105 	udpdata32 = (__be32 *)udpdata;
106 
107 	switch (encap_type) {
108 	default:
109 	case UDP_ENCAP_ESPINUDP:
110 		/* Check if this is a keepalive packet.  If so, eat it. */
111 		if (len == 1 && udpdata[0] == 0xff) {
112 			goto drop;
113 		} else if (len > sizeof(struct ip_esp_hdr) && udpdata32[0] != 0) {
114 			/* ESP Packet without Non-ESP header */
115 			len = sizeof(struct udphdr);
116 		} else
117 			/* Must be an IKE packet.. pass it through */
118 			return 1;
119 		break;
120 	case UDP_ENCAP_ESPINUDP_NON_IKE:
121 		/* Check if this is a keepalive packet.  If so, eat it. */
122 		if (len == 1 && udpdata[0] == 0xff) {
123 			goto drop;
124 		} else if (len > 2 * sizeof(u32) + sizeof(struct ip_esp_hdr) &&
125 			   udpdata32[0] == 0 && udpdata32[1] == 0) {
126 
127 			/* ESP Packet with Non-IKE marker */
128 			len = sizeof(struct udphdr) + 2 * sizeof(u32);
129 		} else
130 			/* Must be an IKE packet.. pass it through */
131 			return 1;
132 		break;
133 	}
134 
135 	/* At this point we are sure that this is an ESPinUDP packet,
136 	 * so we need to remove 'len' bytes from the packet (the UDP
137 	 * header and optional ESP marker bytes) and then modify the
138 	 * protocol to ESP, and then call into the transform receiver.
139 	 */
140 	if (skb_unclone(skb, GFP_ATOMIC))
141 		goto drop;
142 
143 	/* Now we can update and verify the packet length... */
144 	ip6h = ipv6_hdr(skb);
145 	ip6h->payload_len = htons(ntohs(ip6h->payload_len) - len);
146 	if (skb->len < ip6hlen + len) {
147 		/* packet is too small!?! */
148 		goto drop;
149 	}
150 
151 	/* pull the data buffer up to the ESP header and set the
152 	 * transport header to point to ESP.  Keep UDP on the stack
153 	 * for later.
154 	 */
155 	__skb_pull(skb, len);
156 	skb_reset_transport_header(skb);
157 
158 	/* process ESP */
159 	return xfrm6_rcv_encap(skb, IPPROTO_ESP, 0, encap_type);
160 
161 drop:
162 	kfree_skb(skb);
163 	return 0;
164 }
165 
166 int xfrm6_rcv_tnl(struct sk_buff *skb, struct ip6_tnl *t)
167 {
168 	return xfrm6_rcv_spi(skb, skb_network_header(skb)[IP6CB(skb)->nhoff],
169 			     0, t);
170 }
171 EXPORT_SYMBOL(xfrm6_rcv_tnl);
172 
173 int xfrm6_rcv(struct sk_buff *skb)
174 {
175 	return xfrm6_rcv_tnl(skb, NULL);
176 }
177 EXPORT_SYMBOL(xfrm6_rcv);
178 int xfrm6_input_addr(struct sk_buff *skb, xfrm_address_t *daddr,
179 		     xfrm_address_t *saddr, u8 proto)
180 {
181 	struct net *net = dev_net(skb->dev);
182 	struct xfrm_state *x = NULL;
183 	struct sec_path *sp;
184 	int i = 0;
185 
186 	sp = secpath_set(skb);
187 	if (!sp) {
188 		XFRM_INC_STATS(net, LINUX_MIB_XFRMINERROR);
189 		goto drop;
190 	}
191 
192 	if (1 + sp->len == XFRM_MAX_DEPTH) {
193 		XFRM_INC_STATS(net, LINUX_MIB_XFRMINBUFFERERROR);
194 		goto drop;
195 	}
196 
197 	for (i = 0; i < 3; i++) {
198 		xfrm_address_t *dst, *src;
199 
200 		switch (i) {
201 		case 0:
202 			dst = daddr;
203 			src = saddr;
204 			break;
205 		case 1:
206 			/* lookup state with wild-card source address */
207 			dst = daddr;
208 			src = (xfrm_address_t *)&in6addr_any;
209 			break;
210 		default:
211 			/* lookup state with wild-card addresses */
212 			dst = (xfrm_address_t *)&in6addr_any;
213 			src = (xfrm_address_t *)&in6addr_any;
214 			break;
215 		}
216 
217 		x = xfrm_state_lookup_byaddr(net, skb->mark, dst, src, proto, AF_INET6);
218 		if (!x)
219 			continue;
220 
221 		spin_lock(&x->lock);
222 
223 		if ((!i || (x->props.flags & XFRM_STATE_WILDRECV)) &&
224 		    likely(x->km.state == XFRM_STATE_VALID) &&
225 		    !xfrm_state_check_expire(x)) {
226 			spin_unlock(&x->lock);
227 			if (x->type->input(x, skb) > 0) {
228 				/* found a valid state */
229 				break;
230 			}
231 		} else
232 			spin_unlock(&x->lock);
233 
234 		xfrm_state_put(x);
235 		x = NULL;
236 	}
237 
238 	if (!x) {
239 		XFRM_INC_STATS(net, LINUX_MIB_XFRMINNOSTATES);
240 		xfrm_audit_state_notfound_simple(skb, AF_INET6);
241 		goto drop;
242 	}
243 
244 	sp->xvec[sp->len++] = x;
245 
246 	spin_lock(&x->lock);
247 
248 	x->curlft.bytes += skb->len;
249 	x->curlft.packets++;
250 
251 	spin_unlock(&x->lock);
252 
253 	return 1;
254 
255 drop:
256 	return -1;
257 }
258 EXPORT_SYMBOL(xfrm6_input_addr);
259