[NETFILTER]: add type parameter to ip_route_me_harder
[linux-2.6.git] / net / ipv4 / netfilter.c
1 /* IPv4 specific functions of netfilter core */
2 #include <linux/kernel.h>
3 #include <linux/netfilter.h>
4 #include <linux/netfilter_ipv4.h>
5 #include <linux/ip.h>
6 #include <net/route.h>
7 #include <net/xfrm.h>
8 #include <net/ip.h>
9
10 /* route_me_harder function, used by iptable_nat, iptable_mangle + ip_queue */
11 int ip_route_me_harder(struct sk_buff **pskb, unsigned addr_type)
12 {
13         struct iphdr *iph = (*pskb)->nh.iph;
14         struct rtable *rt;
15         struct flowi fl = {};
16         struct dst_entry *odst;
17         unsigned int hh_len;
18
19         if (addr_type == RTN_UNSPEC)
20                 addr_type = inet_addr_type(iph->saddr);
21
22         /* some non-standard hacks like ipt_REJECT.c:send_reset() can cause
23          * packets with foreign saddr to appear on the NF_IP_LOCAL_OUT hook.
24          */
25         if (addr_type == RTN_LOCAL) {
26                 fl.nl_u.ip4_u.daddr = iph->daddr;
27                 fl.nl_u.ip4_u.saddr = iph->saddr;
28                 fl.nl_u.ip4_u.tos = RT_TOS(iph->tos);
29                 fl.oif = (*pskb)->sk ? (*pskb)->sk->sk_bound_dev_if : 0;
30 #ifdef CONFIG_IP_ROUTE_FWMARK
31                 fl.nl_u.ip4_u.fwmark = (*pskb)->nfmark;
32 #endif
33                 if (ip_route_output_key(&rt, &fl) != 0)
34                         return -1;
35
36                 /* Drop old route. */
37                 dst_release((*pskb)->dst);
38                 (*pskb)->dst = &rt->u.dst;
39         } else {
40                 /* non-local src, find valid iif to satisfy
41                  * rp-filter when calling ip_route_input. */
42                 fl.nl_u.ip4_u.daddr = iph->saddr;
43                 if (ip_route_output_key(&rt, &fl) != 0)
44                         return -1;
45
46                 odst = (*pskb)->dst;
47                 if (ip_route_input(*pskb, iph->daddr, iph->saddr,
48                                    RT_TOS(iph->tos), rt->u.dst.dev) != 0) {
49                         dst_release(&rt->u.dst);
50                         return -1;
51                 }
52                 dst_release(&rt->u.dst);
53                 dst_release(odst);
54         }
55         
56         if ((*pskb)->dst->error)
57                 return -1;
58
59 #ifdef CONFIG_XFRM
60         if (!(IPCB(*pskb)->flags & IPSKB_XFRM_TRANSFORMED) &&
61             xfrm_decode_session(*pskb, &fl, AF_INET) == 0)
62                 if (xfrm_lookup(&(*pskb)->dst, &fl, (*pskb)->sk, 0))
63                         return -1;
64 #endif
65
66         /* Change in oif may mean change in hh_len. */
67         hh_len = (*pskb)->dst->dev->hard_header_len;
68         if (skb_headroom(*pskb) < hh_len) {
69                 struct sk_buff *nskb;
70
71                 nskb = skb_realloc_headroom(*pskb, hh_len);
72                 if (!nskb) 
73                         return -1;
74                 if ((*pskb)->sk)
75                         skb_set_owner_w(nskb, (*pskb)->sk);
76                 kfree_skb(*pskb);
77                 *pskb = nskb;
78         }
79
80         return 0;
81 }
82 EXPORT_SYMBOL(ip_route_me_harder);
83
84 #ifdef CONFIG_XFRM
85 int ip_xfrm_me_harder(struct sk_buff **pskb)
86 {
87         struct flowi fl;
88         unsigned int hh_len;
89         struct dst_entry *dst;
90
91         if (IPCB(*pskb)->flags & IPSKB_XFRM_TRANSFORMED)
92                 return 0;
93         if (xfrm_decode_session(*pskb, &fl, AF_INET) < 0)
94                 return -1;
95
96         dst = (*pskb)->dst;
97         if (dst->xfrm)
98                 dst = ((struct xfrm_dst *)dst)->route;
99         dst_hold(dst);
100
101         if (xfrm_lookup(&dst, &fl, (*pskb)->sk, 0) < 0)
102                 return -1;
103
104         dst_release((*pskb)->dst);
105         (*pskb)->dst = dst;
106
107         /* Change in oif may mean change in hh_len. */
108         hh_len = (*pskb)->dst->dev->hard_header_len;
109         if (skb_headroom(*pskb) < hh_len) {
110                 struct sk_buff *nskb;
111
112                 nskb = skb_realloc_headroom(*pskb, hh_len);
113                 if (!nskb)
114                         return -1;
115                 if ((*pskb)->sk)
116                         skb_set_owner_w(nskb, (*pskb)->sk);
117                 kfree_skb(*pskb);
118                 *pskb = nskb;
119         }
120         return 0;
121 }
122 EXPORT_SYMBOL(ip_xfrm_me_harder);
123 #endif
124
125 void (*ip_nat_decode_session)(struct sk_buff *, struct flowi *);
126 EXPORT_SYMBOL(ip_nat_decode_session);
127
128 /*
129  * Extra routing may needed on local out, as the QUEUE target never
130  * returns control to the table.
131  */
132
133 struct ip_rt_info {
134         __be32 daddr;
135         __be32 saddr;
136         u_int8_t tos;
137 };
138
139 static void nf_ip_saveroute(const struct sk_buff *skb, struct nf_info *info)
140 {
141         struct ip_rt_info *rt_info = nf_info_reroute(info);
142
143         if (info->hook == NF_IP_LOCAL_OUT) {
144                 const struct iphdr *iph = skb->nh.iph;
145
146                 rt_info->tos = iph->tos;
147                 rt_info->daddr = iph->daddr;
148                 rt_info->saddr = iph->saddr;
149         }
150 }
151
152 static int nf_ip_reroute(struct sk_buff **pskb, const struct nf_info *info)
153 {
154         const struct ip_rt_info *rt_info = nf_info_reroute(info);
155
156         if (info->hook == NF_IP_LOCAL_OUT) {
157                 struct iphdr *iph = (*pskb)->nh.iph;
158
159                 if (!(iph->tos == rt_info->tos
160                       && iph->daddr == rt_info->daddr
161                       && iph->saddr == rt_info->saddr))
162                         return ip_route_me_harder(pskb, RTN_UNSPEC);
163         }
164         return 0;
165 }
166
167 unsigned int nf_ip_checksum(struct sk_buff *skb, unsigned int hook,
168                             unsigned int dataoff, u_int8_t protocol)
169 {
170         struct iphdr *iph = skb->nh.iph;
171         unsigned int csum = 0;
172
173         switch (skb->ip_summed) {
174         case CHECKSUM_COMPLETE:
175                 if (hook != NF_IP_PRE_ROUTING && hook != NF_IP_LOCAL_IN)
176                         break;
177                 if ((protocol == 0 && !(u16)csum_fold(skb->csum)) ||
178                     !csum_tcpudp_magic(iph->saddr, iph->daddr,
179                                        skb->len - dataoff, protocol,
180                                        skb->csum)) {
181                         skb->ip_summed = CHECKSUM_UNNECESSARY;
182                         break;
183                 }
184                 /* fall through */
185         case CHECKSUM_NONE:
186                 if (protocol == 0)
187                         skb->csum = 0;
188                 else
189                         skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr,
190                                                        skb->len - dataoff,
191                                                        protocol, 0);
192                 csum = __skb_checksum_complete(skb);
193         }
194         return csum;
195 }
196
197 EXPORT_SYMBOL(nf_ip_checksum);
198
199 static struct nf_afinfo nf_ip_afinfo = {
200         .family         = AF_INET,
201         .checksum       = nf_ip_checksum,
202         .saveroute      = nf_ip_saveroute,
203         .reroute        = nf_ip_reroute,
204         .route_key_size = sizeof(struct ip_rt_info),
205 };
206
207 static int ipv4_netfilter_init(void)
208 {
209         return nf_register_afinfo(&nf_ip_afinfo);
210 }
211
212 static void ipv4_netfilter_fini(void)
213 {
214         nf_unregister_afinfo(&nf_ip_afinfo);
215 }
216
217 module_init(ipv4_netfilter_init);
218 module_exit(ipv4_netfilter_fini);