tcp: skip cwnd moderation in TCP_CA_Open in tcp_try_to_open
[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 <linux/skbuff.h>
7 #include <linux/gfp.h>
8 #include <linux/export.h>
9 #include <net/route.h>
10 #include <net/xfrm.h>
11 #include <net/ip.h>
12 #include <net/netfilter/nf_queue.h>
13
14 /* route_me_harder function, used by iptable_nat, iptable_mangle + ip_queue */
15 int ip_route_me_harder(struct sk_buff *skb, unsigned addr_type)
16 {
17         struct net *net = dev_net(skb_dst(skb)->dev);
18         const struct iphdr *iph = ip_hdr(skb);
19         struct rtable *rt;
20         struct flowi4 fl4 = {};
21         __be32 saddr = iph->saddr;
22         __u8 flags = skb->sk ? inet_sk_flowi_flags(skb->sk) : 0;
23         unsigned int hh_len;
24
25         if (addr_type == RTN_UNSPEC)
26                 addr_type = inet_addr_type(net, saddr);
27         if (addr_type == RTN_LOCAL || addr_type == RTN_UNICAST)
28                 flags |= FLOWI_FLAG_ANYSRC;
29         else
30                 saddr = 0;
31
32         /* some non-standard hacks like ipt_REJECT.c:send_reset() can cause
33          * packets with foreign saddr to appear on the NF_INET_LOCAL_OUT hook.
34          */
35         fl4.daddr = iph->daddr;
36         fl4.saddr = saddr;
37         fl4.flowi4_tos = RT_TOS(iph->tos);
38         fl4.flowi4_oif = skb->sk ? skb->sk->sk_bound_dev_if : 0;
39         fl4.flowi4_mark = skb->mark;
40         fl4.flowi4_flags = flags;
41         rt = ip_route_output_key(net, &fl4);
42         if (IS_ERR(rt))
43                 return -1;
44
45         /* Drop old route. */
46         skb_dst_drop(skb);
47         skb_dst_set(skb, &rt->dst);
48
49         if (skb_dst(skb)->error)
50                 return -1;
51
52 #ifdef CONFIG_XFRM
53         if (!(IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) &&
54             xfrm_decode_session(skb, flowi4_to_flowi(&fl4), AF_INET) == 0) {
55                 struct dst_entry *dst = skb_dst(skb);
56                 skb_dst_set(skb, NULL);
57                 dst = xfrm_lookup(net, dst, flowi4_to_flowi(&fl4), skb->sk, 0);
58                 if (IS_ERR(dst))
59                         return -1;
60                 skb_dst_set(skb, dst);
61         }
62 #endif
63
64         /* Change in oif may mean change in hh_len. */
65         hh_len = skb_dst(skb)->dev->hard_header_len;
66         if (skb_headroom(skb) < hh_len &&
67             pskb_expand_head(skb, hh_len - skb_headroom(skb), 0, GFP_ATOMIC))
68                 return -1;
69
70         return 0;
71 }
72 EXPORT_SYMBOL(ip_route_me_harder);
73
74 #ifdef CONFIG_XFRM
75 int ip_xfrm_me_harder(struct sk_buff *skb)
76 {
77         struct flowi fl;
78         unsigned int hh_len;
79         struct dst_entry *dst;
80
81         if (IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED)
82                 return 0;
83         if (xfrm_decode_session(skb, &fl, AF_INET) < 0)
84                 return -1;
85
86         dst = skb_dst(skb);
87         if (dst->xfrm)
88                 dst = ((struct xfrm_dst *)dst)->route;
89         dst_hold(dst);
90
91         dst = xfrm_lookup(dev_net(dst->dev), dst, &fl, skb->sk, 0);
92         if (IS_ERR(dst))
93                 return -1;
94
95         skb_dst_drop(skb);
96         skb_dst_set(skb, dst);
97
98         /* Change in oif may mean change in hh_len. */
99         hh_len = skb_dst(skb)->dev->hard_header_len;
100         if (skb_headroom(skb) < hh_len &&
101             pskb_expand_head(skb, hh_len - skb_headroom(skb), 0, GFP_ATOMIC))
102                 return -1;
103         return 0;
104 }
105 EXPORT_SYMBOL(ip_xfrm_me_harder);
106 #endif
107
108 void (*ip_nat_decode_session)(struct sk_buff *, struct flowi *);
109 EXPORT_SYMBOL(ip_nat_decode_session);
110
111 /*
112  * Extra routing may needed on local out, as the QUEUE target never
113  * returns control to the table.
114  */
115
116 struct ip_rt_info {
117         __be32 daddr;
118         __be32 saddr;
119         u_int8_t tos;
120         u_int32_t mark;
121 };
122
123 static void nf_ip_saveroute(const struct sk_buff *skb,
124                             struct nf_queue_entry *entry)
125 {
126         struct ip_rt_info *rt_info = nf_queue_entry_reroute(entry);
127
128         if (entry->hook == NF_INET_LOCAL_OUT) {
129                 const struct iphdr *iph = ip_hdr(skb);
130
131                 rt_info->tos = iph->tos;
132                 rt_info->daddr = iph->daddr;
133                 rt_info->saddr = iph->saddr;
134                 rt_info->mark = skb->mark;
135         }
136 }
137
138 static int nf_ip_reroute(struct sk_buff *skb,
139                          const struct nf_queue_entry *entry)
140 {
141         const struct ip_rt_info *rt_info = nf_queue_entry_reroute(entry);
142
143         if (entry->hook == NF_INET_LOCAL_OUT) {
144                 const struct iphdr *iph = ip_hdr(skb);
145
146                 if (!(iph->tos == rt_info->tos &&
147                       skb->mark == rt_info->mark &&
148                       iph->daddr == rt_info->daddr &&
149                       iph->saddr == rt_info->saddr))
150                         return ip_route_me_harder(skb, RTN_UNSPEC);
151         }
152         return 0;
153 }
154
155 __sum16 nf_ip_checksum(struct sk_buff *skb, unsigned int hook,
156                             unsigned int dataoff, u_int8_t protocol)
157 {
158         const struct iphdr *iph = ip_hdr(skb);
159         __sum16 csum = 0;
160
161         switch (skb->ip_summed) {
162         case CHECKSUM_COMPLETE:
163                 if (hook != NF_INET_PRE_ROUTING && hook != NF_INET_LOCAL_IN)
164                         break;
165                 if ((protocol == 0 && !csum_fold(skb->csum)) ||
166                     !csum_tcpudp_magic(iph->saddr, iph->daddr,
167                                        skb->len - dataoff, protocol,
168                                        skb->csum)) {
169                         skb->ip_summed = CHECKSUM_UNNECESSARY;
170                         break;
171                 }
172                 /* fall through */
173         case CHECKSUM_NONE:
174                 if (protocol == 0)
175                         skb->csum = 0;
176                 else
177                         skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr,
178                                                        skb->len - dataoff,
179                                                        protocol, 0);
180                 csum = __skb_checksum_complete(skb);
181         }
182         return csum;
183 }
184 EXPORT_SYMBOL(nf_ip_checksum);
185
186 static __sum16 nf_ip_checksum_partial(struct sk_buff *skb, unsigned int hook,
187                                       unsigned int dataoff, unsigned int len,
188                                       u_int8_t protocol)
189 {
190         const struct iphdr *iph = ip_hdr(skb);
191         __sum16 csum = 0;
192
193         switch (skb->ip_summed) {
194         case CHECKSUM_COMPLETE:
195                 if (len == skb->len - dataoff)
196                         return nf_ip_checksum(skb, hook, dataoff, protocol);
197                 /* fall through */
198         case CHECKSUM_NONE:
199                 skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr, protocol,
200                                                skb->len - dataoff, 0);
201                 skb->ip_summed = CHECKSUM_NONE;
202                 return __skb_checksum_complete_head(skb, dataoff + len);
203         }
204         return csum;
205 }
206
207 static int nf_ip_route(struct net *net, struct dst_entry **dst,
208                        struct flowi *fl, bool strict __always_unused)
209 {
210         struct rtable *rt = ip_route_output_key(net, &fl->u.ip4);
211         if (IS_ERR(rt))
212                 return PTR_ERR(rt);
213         *dst = &rt->dst;
214         return 0;
215 }
216
217 static const struct nf_afinfo nf_ip_afinfo = {
218         .family                 = AF_INET,
219         .checksum               = nf_ip_checksum,
220         .checksum_partial       = nf_ip_checksum_partial,
221         .route                  = nf_ip_route,
222         .saveroute              = nf_ip_saveroute,
223         .reroute                = nf_ip_reroute,
224         .route_key_size         = sizeof(struct ip_rt_info),
225 };
226
227 static int ipv4_netfilter_init(void)
228 {
229         return nf_register_afinfo(&nf_ip_afinfo);
230 }
231
232 static void ipv4_netfilter_fini(void)
233 {
234         nf_unregister_afinfo(&nf_ip_afinfo);
235 }
236
237 module_init(ipv4_netfilter_init);
238 module_exit(ipv4_netfilter_fini);
239
240 #ifdef CONFIG_SYSCTL
241 struct ctl_path nf_net_ipv4_netfilter_sysctl_path[] = {
242         { .procname = "net", },
243         { .procname = "ipv4", },
244         { .procname = "netfilter", },
245         { }
246 };
247 EXPORT_SYMBOL_GPL(nf_net_ipv4_netfilter_sysctl_path);
248 #endif /* CONFIG_SYSCTL */