| 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 <net/route.h> |
| 8 | #include <net/xfrm.h> |
| 9 | #include <net/ip.h> |
| 10 | #include <net/netfilter/nf_queue.h> |
| 11 | |
| 12 | /* route_me_harder function, used by iptable_nat, iptable_mangle + ip_queue */ |
| 13 | int ip_route_me_harder(struct sk_buff *skb, unsigned addr_type) |
| 14 | { |
| 15 | struct net *net = dev_net(skb_dst(skb)->dev); |
| 16 | const struct iphdr *iph = ip_hdr(skb); |
| 17 | struct rtable *rt; |
| 18 | struct flowi fl = {}; |
| 19 | struct dst_entry *odst; |
| 20 | unsigned int hh_len; |
| 21 | unsigned int type; |
| 22 | |
| 23 | type = inet_addr_type(net, iph->saddr); |
| 24 | if (skb->sk && inet_sk(skb->sk)->transparent) |
| 25 | type = RTN_LOCAL; |
| 26 | if (addr_type == RTN_UNSPEC) |
| 27 | addr_type = type; |
| 28 | |
| 29 | /* some non-standard hacks like ipt_REJECT.c:send_reset() can cause |
| 30 | * packets with foreign saddr to appear on the NF_INET_LOCAL_OUT hook. |
| 31 | */ |
| 32 | if (addr_type == RTN_LOCAL) { |
| 33 | fl.nl_u.ip4_u.daddr = iph->daddr; |
| 34 | if (type == RTN_LOCAL) |
| 35 | fl.nl_u.ip4_u.saddr = iph->saddr; |
| 36 | fl.nl_u.ip4_u.tos = RT_TOS(iph->tos); |
| 37 | fl.oif = skb->sk ? skb->sk->sk_bound_dev_if : 0; |
| 38 | fl.mark = skb->mark; |
| 39 | fl.flags = skb->sk ? inet_sk_flowi_flags(skb->sk) : 0; |
| 40 | if (ip_route_output_key(net, &rt, &fl) != 0) |
| 41 | return -1; |
| 42 | |
| 43 | /* Drop old route. */ |
| 44 | skb_dst_drop(skb); |
| 45 | skb_dst_set(skb, &rt->u.dst); |
| 46 | } else { |
| 47 | /* non-local src, find valid iif to satisfy |
| 48 | * rp-filter when calling ip_route_input. */ |
| 49 | fl.nl_u.ip4_u.daddr = iph->saddr; |
| 50 | if (ip_route_output_key(net, &rt, &fl) != 0) |
| 51 | return -1; |
| 52 | |
| 53 | odst = skb_dst(skb); |
| 54 | if (ip_route_input(skb, iph->daddr, iph->saddr, |
| 55 | RT_TOS(iph->tos), rt->u.dst.dev) != 0) { |
| 56 | dst_release(&rt->u.dst); |
| 57 | return -1; |
| 58 | } |
| 59 | dst_release(&rt->u.dst); |
| 60 | dst_release(odst); |
| 61 | } |
| 62 | |
| 63 | if (skb_dst(skb)->error) |
| 64 | return -1; |
| 65 | |
| 66 | #ifdef CONFIG_XFRM |
| 67 | if (!(IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) && |
| 68 | xfrm_decode_session(skb, &fl, AF_INET) == 0) { |
| 69 | struct dst_entry *dst = skb_dst(skb); |
| 70 | skb_dst_set(skb, NULL); |
| 71 | if (xfrm_lookup(net, &dst, &fl, skb->sk, 0)) |
| 72 | return -1; |
| 73 | skb_dst_set(skb, dst); |
| 74 | } |
| 75 | #endif |
| 76 | |
| 77 | /* Change in oif may mean change in hh_len. */ |
| 78 | hh_len = skb_dst(skb)->dev->hard_header_len; |
| 79 | if (skb_headroom(skb) < hh_len && |
| 80 | pskb_expand_head(skb, hh_len - skb_headroom(skb), 0, GFP_ATOMIC)) |
| 81 | return -1; |
| 82 | |
| 83 | return 0; |
| 84 | } |
| 85 | EXPORT_SYMBOL(ip_route_me_harder); |
| 86 | |
| 87 | #ifdef CONFIG_XFRM |
| 88 | int ip_xfrm_me_harder(struct sk_buff *skb) |
| 89 | { |
| 90 | struct flowi fl; |
| 91 | unsigned int hh_len; |
| 92 | struct dst_entry *dst; |
| 93 | |
| 94 | if (IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) |
| 95 | return 0; |
| 96 | if (xfrm_decode_session(skb, &fl, AF_INET) < 0) |
| 97 | return -1; |
| 98 | |
| 99 | dst = skb_dst(skb); |
| 100 | if (dst->xfrm) |
| 101 | dst = ((struct xfrm_dst *)dst)->route; |
| 102 | dst_hold(dst); |
| 103 | |
| 104 | if (xfrm_lookup(dev_net(dst->dev), &dst, &fl, skb->sk, 0) < 0) |
| 105 | return -1; |
| 106 | |
| 107 | skb_dst_drop(skb); |
| 108 | skb_dst_set(skb, dst); |
| 109 | |
| 110 | /* Change in oif may mean change in hh_len. */ |
| 111 | hh_len = skb_dst(skb)->dev->hard_header_len; |
| 112 | if (skb_headroom(skb) < hh_len && |
| 113 | pskb_expand_head(skb, hh_len - skb_headroom(skb), 0, GFP_ATOMIC)) |
| 114 | return -1; |
| 115 | return 0; |
| 116 | } |
| 117 | EXPORT_SYMBOL(ip_xfrm_me_harder); |
| 118 | #endif |
| 119 | |
| 120 | void (*ip_nat_decode_session)(struct sk_buff *, struct flowi *); |
| 121 | EXPORT_SYMBOL(ip_nat_decode_session); |
| 122 | |
| 123 | /* |
| 124 | * Extra routing may needed on local out, as the QUEUE target never |
| 125 | * returns control to the table. |
| 126 | */ |
| 127 | |
| 128 | struct ip_rt_info { |
| 129 | __be32 daddr; |
| 130 | __be32 saddr; |
| 131 | u_int8_t tos; |
| 132 | u_int32_t mark; |
| 133 | }; |
| 134 | |
| 135 | static void nf_ip_saveroute(const struct sk_buff *skb, |
| 136 | struct nf_queue_entry *entry) |
| 137 | { |
| 138 | struct ip_rt_info *rt_info = nf_queue_entry_reroute(entry); |
| 139 | |
| 140 | if (entry->hook == NF_INET_LOCAL_OUT) { |
| 141 | const struct iphdr *iph = ip_hdr(skb); |
| 142 | |
| 143 | rt_info->tos = iph->tos; |
| 144 | rt_info->daddr = iph->daddr; |
| 145 | rt_info->saddr = iph->saddr; |
| 146 | rt_info->mark = skb->mark; |
| 147 | } |
| 148 | } |
| 149 | |
| 150 | static int nf_ip_reroute(struct sk_buff *skb, |
| 151 | const struct nf_queue_entry *entry) |
| 152 | { |
| 153 | const struct ip_rt_info *rt_info = nf_queue_entry_reroute(entry); |
| 154 | |
| 155 | if (entry->hook == NF_INET_LOCAL_OUT) { |
| 156 | const struct iphdr *iph = ip_hdr(skb); |
| 157 | |
| 158 | if (!(iph->tos == rt_info->tos && |
| 159 | skb->mark == rt_info->mark && |
| 160 | iph->daddr == rt_info->daddr && |
| 161 | iph->saddr == rt_info->saddr)) |
| 162 | return ip_route_me_harder(skb, RTN_UNSPEC); |
| 163 | } |
| 164 | return 0; |
| 165 | } |
| 166 | |
| 167 | __sum16 nf_ip_checksum(struct sk_buff *skb, unsigned int hook, |
| 168 | unsigned int dataoff, u_int8_t protocol) |
| 169 | { |
| 170 | const struct iphdr *iph = ip_hdr(skb); |
| 171 | __sum16 csum = 0; |
| 172 | |
| 173 | switch (skb->ip_summed) { |
| 174 | case CHECKSUM_COMPLETE: |
| 175 | if (hook != NF_INET_PRE_ROUTING && hook != NF_INET_LOCAL_IN) |
| 176 | break; |
| 177 | if ((protocol == 0 && !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 | EXPORT_SYMBOL(nf_ip_checksum); |
| 197 | |
| 198 | static __sum16 nf_ip_checksum_partial(struct sk_buff *skb, unsigned int hook, |
| 199 | unsigned int dataoff, unsigned int len, |
| 200 | u_int8_t protocol) |
| 201 | { |
| 202 | const struct iphdr *iph = ip_hdr(skb); |
| 203 | __sum16 csum = 0; |
| 204 | |
| 205 | switch (skb->ip_summed) { |
| 206 | case CHECKSUM_COMPLETE: |
| 207 | if (len == skb->len - dataoff) |
| 208 | return nf_ip_checksum(skb, hook, dataoff, protocol); |
| 209 | /* fall through */ |
| 210 | case CHECKSUM_NONE: |
| 211 | skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr, protocol, |
| 212 | skb->len - dataoff, 0); |
| 213 | skb->ip_summed = CHECKSUM_NONE; |
| 214 | csum = __skb_checksum_complete_head(skb, dataoff + len); |
| 215 | if (!csum) |
| 216 | skb->ip_summed = CHECKSUM_UNNECESSARY; |
| 217 | } |
| 218 | return csum; |
| 219 | } |
| 220 | |
| 221 | static int nf_ip_route(struct dst_entry **dst, struct flowi *fl) |
| 222 | { |
| 223 | return ip_route_output_key(&init_net, (struct rtable **)dst, fl); |
| 224 | } |
| 225 | |
| 226 | static const struct nf_afinfo nf_ip_afinfo = { |
| 227 | .family = AF_INET, |
| 228 | .checksum = nf_ip_checksum, |
| 229 | .checksum_partial = nf_ip_checksum_partial, |
| 230 | .route = nf_ip_route, |
| 231 | .saveroute = nf_ip_saveroute, |
| 232 | .reroute = nf_ip_reroute, |
| 233 | .route_key_size = sizeof(struct ip_rt_info), |
| 234 | }; |
| 235 | |
| 236 | static int ipv4_netfilter_init(void) |
| 237 | { |
| 238 | return nf_register_afinfo(&nf_ip_afinfo); |
| 239 | } |
| 240 | |
| 241 | static void ipv4_netfilter_fini(void) |
| 242 | { |
| 243 | nf_unregister_afinfo(&nf_ip_afinfo); |
| 244 | } |
| 245 | |
| 246 | module_init(ipv4_netfilter_init); |
| 247 | module_exit(ipv4_netfilter_fini); |
| 248 | |
| 249 | #ifdef CONFIG_SYSCTL |
| 250 | struct ctl_path nf_net_ipv4_netfilter_sysctl_path[] = { |
| 251 | { .procname = "net", }, |
| 252 | { .procname = "ipv4", }, |
| 253 | { .procname = "netfilter", }, |
| 254 | { } |
| 255 | }; |
| 256 | EXPORT_SYMBOL_GPL(nf_net_ipv4_netfilter_sysctl_path); |
| 257 | #endif /* CONFIG_SYSCTL */ |