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 
xfrm6_rcv_spi(struct sk_buff * skb,int nexthdr,__be32 spi,struct ip6_tnl * t)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 
xfrm6_transport_finish2(struct net * net,struct sock * sk,struct sk_buff * skb)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 
xfrm6_transport_finish(struct sk_buff * skb,int async)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  */
xfrm6_udp_encap_rcv(struct sock * sk,struct sk_buff * skb)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 
85 	__u8 *udpdata;
86 	__be32 *udpdata32;
87 	__u16 encap_type = up->encap_type;
88 
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 			goto drop;
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 	case UDP_ENCAP_ESPINUDP_NON_IKE:
118 		/* Check if this is a keepalive packet.  If so, eat it. */
119 		if (len == 1 && udpdata[0] == 0xff) {
120 			goto drop;
121 		} else if (len > 2 * sizeof(u32) + sizeof(struct ip_esp_hdr) &&
122 			   udpdata32[0] == 0 && udpdata32[1] == 0) {
123 
124 			/* ESP Packet with Non-IKE marker */
125 			len = sizeof(struct udphdr) + 2 * sizeof(u32);
126 		} else
127 			/* Must be an IKE packet.. pass it through */
128 			return 1;
129 		break;
130 	}
131 
132 	/* At this point we are sure that this is an ESPinUDP packet,
133 	 * so we need to remove 'len' bytes from the packet (the UDP
134 	 * header and optional ESP marker bytes) and then modify the
135 	 * protocol to ESP, and then call into the transform receiver.
136 	 */
137 	if (skb_unclone(skb, GFP_ATOMIC))
138 		goto drop;
139 
140 	/* Now we can update and verify the packet length... */
141 	ip6h = ipv6_hdr(skb);
142 	ip6h->payload_len = htons(ntohs(ip6h->payload_len) - len);
143 	if (skb->len < ip6hlen + len) {
144 		/* packet is too small!?! */
145 		goto drop;
146 	}
147 
148 	/* pull the data buffer up to the ESP header and set the
149 	 * transport header to point to ESP.  Keep UDP on the stack
150 	 * for later.
151 	 */
152 	__skb_pull(skb, len);
153 	skb_reset_transport_header(skb);
154 
155 	/* process ESP */
156 	return xfrm6_rcv_encap(skb, IPPROTO_ESP, 0, encap_type);
157 
158 drop:
159 	kfree_skb(skb);
160 	return 0;
161 }
162 
xfrm6_rcv_tnl(struct sk_buff * skb,struct ip6_tnl * t)163 int xfrm6_rcv_tnl(struct sk_buff *skb, struct ip6_tnl *t)
164 {
165 	return xfrm6_rcv_spi(skb, skb_network_header(skb)[IP6CB(skb)->nhoff],
166 			     0, t);
167 }
168 EXPORT_SYMBOL(xfrm6_rcv_tnl);
169 
xfrm6_rcv(struct sk_buff * skb)170 int xfrm6_rcv(struct sk_buff *skb)
171 {
172 	return xfrm6_rcv_tnl(skb, NULL);
173 }
174 EXPORT_SYMBOL(xfrm6_rcv);
xfrm6_input_addr(struct sk_buff * skb,xfrm_address_t * daddr,xfrm_address_t * saddr,u8 proto)175 int xfrm6_input_addr(struct sk_buff *skb, xfrm_address_t *daddr,
176 		     xfrm_address_t *saddr, u8 proto)
177 {
178 	struct net *net = dev_net(skb->dev);
179 	struct xfrm_state *x = NULL;
180 	struct sec_path *sp;
181 	int i = 0;
182 
183 	sp = secpath_set(skb);
184 	if (!sp) {
185 		XFRM_INC_STATS(net, LINUX_MIB_XFRMINERROR);
186 		goto drop;
187 	}
188 
189 	if (1 + sp->len == XFRM_MAX_DEPTH) {
190 		XFRM_INC_STATS(net, LINUX_MIB_XFRMINBUFFERERROR);
191 		goto drop;
192 	}
193 
194 	for (i = 0; i < 3; i++) {
195 		xfrm_address_t *dst, *src;
196 
197 		switch (i) {
198 		case 0:
199 			dst = daddr;
200 			src = saddr;
201 			break;
202 		case 1:
203 			/* lookup state with wild-card source address */
204 			dst = daddr;
205 			src = (xfrm_address_t *)&in6addr_any;
206 			break;
207 		default:
208 			/* lookup state with wild-card addresses */
209 			dst = (xfrm_address_t *)&in6addr_any;
210 			src = (xfrm_address_t *)&in6addr_any;
211 			break;
212 		}
213 
214 		x = xfrm_state_lookup_byaddr(net, skb->mark, dst, src, proto, AF_INET6);
215 		if (!x)
216 			continue;
217 
218 		spin_lock(&x->lock);
219 
220 		if ((!i || (x->props.flags & XFRM_STATE_WILDRECV)) &&
221 		    likely(x->km.state == XFRM_STATE_VALID) &&
222 		    !xfrm_state_check_expire(x)) {
223 			spin_unlock(&x->lock);
224 			if (x->type->input(x, skb) > 0) {
225 				/* found a valid state */
226 				break;
227 			}
228 		} else
229 			spin_unlock(&x->lock);
230 
231 		xfrm_state_put(x);
232 		x = NULL;
233 	}
234 
235 	if (!x) {
236 		XFRM_INC_STATS(net, LINUX_MIB_XFRMINNOSTATES);
237 		xfrm_audit_state_notfound_simple(skb, AF_INET6);
238 		goto drop;
239 	}
240 
241 	sp->xvec[sp->len++] = x;
242 
243 	spin_lock(&x->lock);
244 
245 	x->curlft.bytes += skb->len;
246 	x->curlft.packets++;
247 
248 	spin_unlock(&x->lock);
249 
250 	return 1;
251 
252 drop:
253 	return -1;
254 }
255 EXPORT_SYMBOL(xfrm6_input_addr);
256