[NETFILTER]: arp_tables: fix NULL pointer dereference
[linux-2.6.git] / net / ipv4 / xfrm4_input.c
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 }