xref: /openbmc/linux/net/ipv4/xfrm4_input.c (revision 87c2ce3b)
1 /*
2  * xfrm4_input.c
3  *
4  * Changes:
5  *	YOSHIFUJI Hideaki @USAGI
6  *		Split up af-specific portion
7  *	Derek Atkins <derek@ihtfp.com>
8  *		Add Encapsulation support
9  *
10  */
11 
12 #include <linux/module.h>
13 #include <linux/string.h>
14 #include <linux/netfilter.h>
15 #include <linux/netfilter_ipv4.h>
16 #include <net/inet_ecn.h>
17 #include <net/ip.h>
18 #include <net/xfrm.h>
19 
20 int xfrm4_rcv(struct sk_buff *skb)
21 {
22 	return xfrm4_rcv_encap(skb, 0);
23 }
24 
25 EXPORT_SYMBOL(xfrm4_rcv);
26 
27 static inline void ipip_ecn_decapsulate(struct sk_buff *skb)
28 {
29 	struct iphdr *outer_iph = skb->nh.iph;
30 	struct iphdr *inner_iph = skb->h.ipiph;
31 
32 	if (INET_ECN_is_ce(outer_iph->tos))
33 		IP_ECN_set_ce(inner_iph);
34 }
35 
36 static int xfrm4_parse_spi(struct sk_buff *skb, u8 nexthdr, u32 *spi, u32 *seq)
37 {
38 	switch (nexthdr) {
39 	case IPPROTO_IPIP:
40 		if (!pskb_may_pull(skb, sizeof(struct iphdr)))
41 			return -EINVAL;
42 		*spi = skb->nh.iph->saddr;
43 		*seq = 0;
44 		return 0;
45 	}
46 
47 	return xfrm_parse_spi(skb, nexthdr, spi, seq);
48 }
49 
50 #ifdef CONFIG_NETFILTER
51 static inline int xfrm4_rcv_encap_finish(struct sk_buff *skb)
52 {
53 	struct iphdr *iph = skb->nh.iph;
54 
55 	if (skb->dst == NULL) {
56 		if (ip_route_input(skb, iph->daddr, iph->saddr, iph->tos,
57 		                   skb->dev))
58 			goto drop;
59 	}
60 	return dst_input(skb);
61 drop:
62 	kfree_skb(skb);
63 	return NET_RX_DROP;
64 }
65 #endif
66 
67 int xfrm4_rcv_encap(struct sk_buff *skb, __u16 encap_type)
68 {
69 	int err;
70 	u32 spi, seq;
71 	struct sec_decap_state xfrm_vec[XFRM_MAX_DEPTH];
72 	struct xfrm_state *x;
73 	int xfrm_nr = 0;
74 	int decaps = 0;
75 
76 	if ((err = xfrm4_parse_spi(skb, skb->nh.iph->protocol, &spi, &seq)) != 0)
77 		goto drop;
78 
79 	do {
80 		struct iphdr *iph = skb->nh.iph;
81 
82 		if (xfrm_nr == XFRM_MAX_DEPTH)
83 			goto drop;
84 
85 		x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, spi, iph->protocol, AF_INET);
86 		if (x == NULL)
87 			goto drop;
88 
89 		spin_lock(&x->lock);
90 		if (unlikely(x->km.state != XFRM_STATE_VALID))
91 			goto drop_unlock;
92 
93 		if (x->props.replay_window && xfrm_replay_check(x, seq))
94 			goto drop_unlock;
95 
96 		if (xfrm_state_check_expire(x))
97 			goto drop_unlock;
98 
99 		xfrm_vec[xfrm_nr].decap.decap_type = encap_type;
100 		if (x->type->input(x, &(xfrm_vec[xfrm_nr].decap), skb))
101 			goto drop_unlock;
102 
103 		/* only the first xfrm gets the encap type */
104 		encap_type = 0;
105 
106 		if (x->props.replay_window)
107 			xfrm_replay_advance(x, seq);
108 
109 		x->curlft.bytes += skb->len;
110 		x->curlft.packets++;
111 
112 		spin_unlock(&x->lock);
113 
114 		xfrm_vec[xfrm_nr++].xvec = x;
115 
116 		iph = skb->nh.iph;
117 
118 		if (x->props.mode) {
119 			if (iph->protocol != IPPROTO_IPIP)
120 				goto drop;
121 			if (!pskb_may_pull(skb, sizeof(struct iphdr)))
122 				goto drop;
123 			if (skb_cloned(skb) &&
124 			    pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
125 				goto drop;
126 			if (x->props.flags & XFRM_STATE_DECAP_DSCP)
127 				ipv4_copy_dscp(iph, skb->h.ipiph);
128 			if (!(x->props.flags & XFRM_STATE_NOECN))
129 				ipip_ecn_decapsulate(skb);
130 			skb->mac.raw = memmove(skb->data - skb->mac_len,
131 					       skb->mac.raw, skb->mac_len);
132 			skb->nh.raw = skb->data;
133 			memset(&(IPCB(skb)->opt), 0, sizeof(struct ip_options));
134 			decaps = 1;
135 			break;
136 		}
137 
138 		if ((err = xfrm_parse_spi(skb, skb->nh.iph->protocol, &spi, &seq)) < 0)
139 			goto drop;
140 	} while (!err);
141 
142 	/* Allocate new secpath or COW existing one. */
143 
144 	if (!skb->sp || atomic_read(&skb->sp->refcnt) != 1) {
145 		struct sec_path *sp;
146 		sp = secpath_dup(skb->sp);
147 		if (!sp)
148 			goto drop;
149 		if (skb->sp)
150 			secpath_put(skb->sp);
151 		skb->sp = sp;
152 	}
153 	if (xfrm_nr + skb->sp->len > XFRM_MAX_DEPTH)
154 		goto drop;
155 
156 	memcpy(skb->sp->x+skb->sp->len, xfrm_vec, xfrm_nr*sizeof(struct sec_decap_state));
157 	skb->sp->len += xfrm_nr;
158 
159 	nf_reset(skb);
160 
161 	if (decaps) {
162 		if (!(skb->dev->flags&IFF_LOOPBACK)) {
163 			dst_release(skb->dst);
164 			skb->dst = NULL;
165 		}
166 		netif_rx(skb);
167 		return 0;
168 	} else {
169 #ifdef CONFIG_NETFILTER
170 		__skb_push(skb, skb->data - skb->nh.raw);
171 		skb->nh.iph->tot_len = htons(skb->len);
172 		ip_send_check(skb->nh.iph);
173 
174 		NF_HOOK(PF_INET, NF_IP_PRE_ROUTING, skb, skb->dev, NULL,
175 		        xfrm4_rcv_encap_finish);
176 		return 0;
177 #else
178 		return -skb->nh.iph->protocol;
179 #endif
180 	}
181 
182 drop_unlock:
183 	spin_unlock(&x->lock);
184 	xfrm_state_put(x);
185 drop:
186 	while (--xfrm_nr >= 0)
187 		xfrm_state_put(xfrm_vec[xfrm_nr].xvec);
188 
189 	kfree_skb(skb);
190 	return 0;
191 }
192