xref: /openbmc/linux/net/ipv6/xfrm6_input.c (revision da097dcc)
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 		/* The full l2 header needs to be preserved so that re-injecting the packet at l2
60 		 * works correctly in the presence of vlan tags.
61 		 */
62 		skb_mac_header_rebuild_full(skb, xo->orig_mac_len);
63 		skb_reset_network_header(skb);
64 		skb_reset_transport_header(skb);
65 		return 0;
66 	}
67 
68 	NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING,
69 		dev_net(skb->dev), NULL, skb, skb->dev, NULL,
70 		xfrm6_transport_finish2);
71 	return 0;
72 }
73 
74 /* If it's a keepalive packet, then just eat it.
75  * If it's an encapsulated packet, then pass it to the
76  * IPsec xfrm input.
77  * Returns 0 if skb passed to xfrm or was dropped.
78  * Returns >0 if skb should be passed to UDP.
79  * Returns <0 if skb should be resubmitted (-ret is protocol)
80  */
81 int xfrm6_udp_encap_rcv(struct sock *sk, struct sk_buff *skb)
82 {
83 	struct udp_sock *up = udp_sk(sk);
84 	struct udphdr *uh;
85 	struct ipv6hdr *ip6h;
86 	int len;
87 	int ip6hlen = sizeof(struct ipv6hdr);
88 	__u8 *udpdata;
89 	__be32 *udpdata32;
90 	u16 encap_type;
91 
92 	if (skb->protocol == htons(ETH_P_IP))
93 		return xfrm4_udp_encap_rcv(sk, skb);
94 
95 	encap_type = READ_ONCE(up->encap_type);
96 	/* if this is not encapsulated socket, then just return now */
97 	if (!encap_type)
98 		return 1;
99 
100 	/* If this is a paged skb, make sure we pull up
101 	 * whatever data we need to look at. */
102 	len = skb->len - sizeof(struct udphdr);
103 	if (!pskb_may_pull(skb, sizeof(struct udphdr) + min(len, 8)))
104 		return 1;
105 
106 	/* Now we can get the pointers */
107 	uh = udp_hdr(skb);
108 	udpdata = (__u8 *)uh + sizeof(struct udphdr);
109 	udpdata32 = (__be32 *)udpdata;
110 
111 	switch (encap_type) {
112 	default:
113 	case UDP_ENCAP_ESPINUDP:
114 		/* Check if this is a keepalive packet.  If so, eat it. */
115 		if (len == 1 && udpdata[0] == 0xff) {
116 			goto drop;
117 		} else if (len > sizeof(struct ip_esp_hdr) && udpdata32[0] != 0) {
118 			/* ESP Packet without Non-ESP header */
119 			len = sizeof(struct udphdr);
120 		} else
121 			/* Must be an IKE packet.. pass it through */
122 			return 1;
123 		break;
124 	case UDP_ENCAP_ESPINUDP_NON_IKE:
125 		/* Check if this is a keepalive packet.  If so, eat it. */
126 		if (len == 1 && udpdata[0] == 0xff) {
127 			goto drop;
128 		} else if (len > 2 * sizeof(u32) + sizeof(struct ip_esp_hdr) &&
129 			   udpdata32[0] == 0 && udpdata32[1] == 0) {
130 
131 			/* ESP Packet with Non-IKE marker */
132 			len = sizeof(struct udphdr) + 2 * sizeof(u32);
133 		} else
134 			/* Must be an IKE packet.. pass it through */
135 			return 1;
136 		break;
137 	}
138 
139 	/* At this point we are sure that this is an ESPinUDP packet,
140 	 * so we need to remove 'len' bytes from the packet (the UDP
141 	 * header and optional ESP marker bytes) and then modify the
142 	 * protocol to ESP, and then call into the transform receiver.
143 	 */
144 	if (skb_unclone(skb, GFP_ATOMIC))
145 		goto drop;
146 
147 	/* Now we can update and verify the packet length... */
148 	ip6h = ipv6_hdr(skb);
149 	ip6h->payload_len = htons(ntohs(ip6h->payload_len) - len);
150 	if (skb->len < ip6hlen + len) {
151 		/* packet is too small!?! */
152 		goto drop;
153 	}
154 
155 	/* pull the data buffer up to the ESP header and set the
156 	 * transport header to point to ESP.  Keep UDP on the stack
157 	 * for later.
158 	 */
159 	__skb_pull(skb, len);
160 	skb_reset_transport_header(skb);
161 
162 	/* process ESP */
163 	return xfrm6_rcv_encap(skb, IPPROTO_ESP, 0, encap_type);
164 
165 drop:
166 	kfree_skb(skb);
167 	return 0;
168 }
169 
170 int xfrm6_rcv_tnl(struct sk_buff *skb, struct ip6_tnl *t)
171 {
172 	return xfrm6_rcv_spi(skb, skb_network_header(skb)[IP6CB(skb)->nhoff],
173 			     0, t);
174 }
175 EXPORT_SYMBOL(xfrm6_rcv_tnl);
176 
177 int xfrm6_rcv(struct sk_buff *skb)
178 {
179 	return xfrm6_rcv_tnl(skb, NULL);
180 }
181 EXPORT_SYMBOL(xfrm6_rcv);
182 int xfrm6_input_addr(struct sk_buff *skb, xfrm_address_t *daddr,
183 		     xfrm_address_t *saddr, u8 proto)
184 {
185 	struct net *net = dev_net(skb->dev);
186 	struct xfrm_state *x = NULL;
187 	struct sec_path *sp;
188 	int i = 0;
189 
190 	sp = secpath_set(skb);
191 	if (!sp) {
192 		XFRM_INC_STATS(net, LINUX_MIB_XFRMINERROR);
193 		goto drop;
194 	}
195 
196 	if (1 + sp->len == XFRM_MAX_DEPTH) {
197 		XFRM_INC_STATS(net, LINUX_MIB_XFRMINBUFFERERROR);
198 		goto drop;
199 	}
200 
201 	for (i = 0; i < 3; i++) {
202 		xfrm_address_t *dst, *src;
203 
204 		switch (i) {
205 		case 0:
206 			dst = daddr;
207 			src = saddr;
208 			break;
209 		case 1:
210 			/* lookup state with wild-card source address */
211 			dst = daddr;
212 			src = (xfrm_address_t *)&in6addr_any;
213 			break;
214 		default:
215 			/* lookup state with wild-card addresses */
216 			dst = (xfrm_address_t *)&in6addr_any;
217 			src = (xfrm_address_t *)&in6addr_any;
218 			break;
219 		}
220 
221 		x = xfrm_state_lookup_byaddr(net, skb->mark, dst, src, proto, AF_INET6);
222 		if (!x)
223 			continue;
224 
225 		spin_lock(&x->lock);
226 
227 		if ((!i || (x->props.flags & XFRM_STATE_WILDRECV)) &&
228 		    likely(x->km.state == XFRM_STATE_VALID) &&
229 		    !xfrm_state_check_expire(x)) {
230 			spin_unlock(&x->lock);
231 			if (x->type->input(x, skb) > 0) {
232 				/* found a valid state */
233 				break;
234 			}
235 		} else
236 			spin_unlock(&x->lock);
237 
238 		xfrm_state_put(x);
239 		x = NULL;
240 	}
241 
242 	if (!x) {
243 		XFRM_INC_STATS(net, LINUX_MIB_XFRMINNOSTATES);
244 		xfrm_audit_state_notfound_simple(skb, AF_INET6);
245 		goto drop;
246 	}
247 
248 	sp->xvec[sp->len++] = x;
249 
250 	spin_lock(&x->lock);
251 
252 	x->curlft.bytes += skb->len;
253 	x->curlft.packets++;
254 
255 	spin_unlock(&x->lock);
256 
257 	return 1;
258 
259 drop:
260 	return -1;
261 }
262 EXPORT_SYMBOL(xfrm6_input_addr);
263