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Commit | Line | Data |
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2cc7d573 | 1 | /* IPv4 specific functions of netfilter core */ |
020b4c12 HW |
2 | #include <linux/kernel.h> |
3 | #include <linux/netfilter.h> | |
2cc7d573 | 4 | #include <linux/netfilter_ipv4.h> |
3e3850e9 | 5 | #include <linux/ip.h> |
2ca7b0ac | 6 | #include <linux/skbuff.h> |
020b4c12 | 7 | #include <net/route.h> |
3e3850e9 PM |
8 | #include <net/xfrm.h> |
9 | #include <net/ip.h> | |
c01cd429 | 10 | #include <net/netfilter/nf_queue.h> |
020b4c12 HW |
11 | |
12 | /* route_me_harder function, used by iptable_nat, iptable_mangle + ip_queue */ | |
3db05fea | 13 | int ip_route_me_harder(struct sk_buff *skb, unsigned addr_type) |
020b4c12 | 14 | { |
adf30907 | 15 | struct net *net = dev_net(skb_dst(skb)->dev); |
3db05fea | 16 | const struct iphdr *iph = ip_hdr(skb); |
020b4c12 HW |
17 | struct rtable *rt; |
18 | struct flowi fl = {}; | |
19 | struct dst_entry *odst; | |
20 | unsigned int hh_len; | |
c68b8b68 | 21 | unsigned int type; |
020b4c12 | 22 | |
b21f8901 | 23 | type = inet_addr_type(net, iph->saddr); |
86b08d86 KK |
24 | if (skb->sk && inet_sk(skb->sk)->transparent) |
25 | type = RTN_LOCAL; | |
b4c4ed17 | 26 | if (addr_type == RTN_UNSPEC) |
c68b8b68 | 27 | addr_type = type; |
b4c4ed17 | 28 | |
020b4c12 | 29 | /* some non-standard hacks like ipt_REJECT.c:send_reset() can cause |
6e23ae2a | 30 | * packets with foreign saddr to appear on the NF_INET_LOCAL_OUT hook. |
020b4c12 | 31 | */ |
b4c4ed17 | 32 | if (addr_type == RTN_LOCAL) { |
020b4c12 | 33 | fl.nl_u.ip4_u.daddr = iph->daddr; |
c68b8b68 PM |
34 | if (type == RTN_LOCAL) |
35 | fl.nl_u.ip4_u.saddr = iph->saddr; | |
020b4c12 | 36 | fl.nl_u.ip4_u.tos = RT_TOS(iph->tos); |
3db05fea HX |
37 | fl.oif = skb->sk ? skb->sk->sk_bound_dev_if : 0; |
38 | fl.mark = skb->mark; | |
86b08d86 | 39 | fl.flags = skb->sk ? inet_sk_flowi_flags(skb->sk) : 0; |
b21f8901 | 40 | if (ip_route_output_key(net, &rt, &fl) != 0) |
020b4c12 HW |
41 | return -1; |
42 | ||
43 | /* Drop old route. */ | |
adf30907 ED |
44 | skb_dst_drop(skb); |
45 | skb_dst_set(skb, &rt->u.dst); | |
020b4c12 HW |
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; | |
b21f8901 | 50 | if (ip_route_output_key(net, &rt, &fl) != 0) |
020b4c12 HW |
51 | return -1; |
52 | ||
adf30907 | 53 | odst = skb_dst(skb); |
3db05fea | 54 | if (ip_route_input(skb, iph->daddr, iph->saddr, |
020b4c12 HW |
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 | } | |
e905a9ed | 62 | |
adf30907 | 63 | if (skb_dst(skb)->error) |
020b4c12 HW |
64 | return -1; |
65 | ||
3e3850e9 | 66 | #ifdef CONFIG_XFRM |
3db05fea | 67 | if (!(IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) && |
adf30907 ED |
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)) | |
3e3850e9 | 72 | return -1; |
adf30907 ED |
73 | skb_dst_set(skb, dst); |
74 | } | |
3e3850e9 PM |
75 | #endif |
76 | ||
020b4c12 | 77 | /* Change in oif may mean change in hh_len. */ |
adf30907 | 78 | hh_len = skb_dst(skb)->dev->hard_header_len; |
3db05fea HX |
79 | if (skb_headroom(skb) < hh_len && |
80 | pskb_expand_head(skb, hh_len - skb_headroom(skb), 0, GFP_ATOMIC)) | |
2ca7b0ac | 81 | return -1; |
020b4c12 HW |
82 | |
83 | return 0; | |
84 | } | |
85 | EXPORT_SYMBOL(ip_route_me_harder); | |
2cc7d573 | 86 | |
ee68cea2 | 87 | #ifdef CONFIG_XFRM |
3db05fea | 88 | int ip_xfrm_me_harder(struct sk_buff *skb) |
ee68cea2 PM |
89 | { |
90 | struct flowi fl; | |
91 | unsigned int hh_len; | |
92 | struct dst_entry *dst; | |
93 | ||
3db05fea | 94 | if (IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) |
ee68cea2 | 95 | return 0; |
3db05fea | 96 | if (xfrm_decode_session(skb, &fl, AF_INET) < 0) |
ee68cea2 PM |
97 | return -1; |
98 | ||
adf30907 | 99 | dst = skb_dst(skb); |
ee68cea2 PM |
100 | if (dst->xfrm) |
101 | dst = ((struct xfrm_dst *)dst)->route; | |
102 | dst_hold(dst); | |
103 | ||
52479b62 | 104 | if (xfrm_lookup(dev_net(dst->dev), &dst, &fl, skb->sk, 0) < 0) |
ee68cea2 PM |
105 | return -1; |
106 | ||
adf30907 ED |
107 | skb_dst_drop(skb); |
108 | skb_dst_set(skb, dst); | |
ee68cea2 PM |
109 | |
110 | /* Change in oif may mean change in hh_len. */ | |
adf30907 | 111 | hh_len = skb_dst(skb)->dev->hard_header_len; |
3db05fea HX |
112 | if (skb_headroom(skb) < hh_len && |
113 | pskb_expand_head(skb, hh_len - skb_headroom(skb), 0, GFP_ATOMIC)) | |
2ca7b0ac | 114 | return -1; |
ee68cea2 PM |
115 | return 0; |
116 | } | |
117 | EXPORT_SYMBOL(ip_xfrm_me_harder); | |
118 | #endif | |
119 | ||
eb9c7ebe PM |
120 | void (*ip_nat_decode_session)(struct sk_buff *, struct flowi *); |
121 | EXPORT_SYMBOL(ip_nat_decode_session); | |
122 | ||
2cc7d573 HW |
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 { | |
59b8bfd8 AV |
129 | __be32 daddr; |
130 | __be32 saddr; | |
2cc7d573 | 131 | u_int8_t tos; |
5f145e44 | 132 | u_int32_t mark; |
2cc7d573 HW |
133 | }; |
134 | ||
02f014d8 PM |
135 | static void nf_ip_saveroute(const struct sk_buff *skb, |
136 | struct nf_queue_entry *entry) | |
2cc7d573 | 137 | { |
02f014d8 | 138 | struct ip_rt_info *rt_info = nf_queue_entry_reroute(entry); |
2cc7d573 | 139 | |
02f014d8 | 140 | if (entry->hook == NF_INET_LOCAL_OUT) { |
eddc9ec5 | 141 | const struct iphdr *iph = ip_hdr(skb); |
2cc7d573 HW |
142 | |
143 | rt_info->tos = iph->tos; | |
144 | rt_info->daddr = iph->daddr; | |
145 | rt_info->saddr = iph->saddr; | |
5f145e44 | 146 | rt_info->mark = skb->mark; |
2cc7d573 HW |
147 | } |
148 | } | |
149 | ||
02f014d8 PM |
150 | static int nf_ip_reroute(struct sk_buff *skb, |
151 | const struct nf_queue_entry *entry) | |
2cc7d573 | 152 | { |
02f014d8 | 153 | const struct ip_rt_info *rt_info = nf_queue_entry_reroute(entry); |
2cc7d573 | 154 | |
02f014d8 | 155 | if (entry->hook == NF_INET_LOCAL_OUT) { |
3db05fea | 156 | const struct iphdr *iph = ip_hdr(skb); |
2cc7d573 | 157 | |
f64f9e71 JP |
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)) | |
3db05fea | 162 | return ip_route_me_harder(skb, RTN_UNSPEC); |
2cc7d573 HW |
163 | } |
164 | return 0; | |
165 | } | |
166 | ||
b51655b9 | 167 | __sum16 nf_ip_checksum(struct sk_buff *skb, unsigned int hook, |
422c346f PM |
168 | unsigned int dataoff, u_int8_t protocol) |
169 | { | |
eddc9ec5 | 170 | const struct iphdr *iph = ip_hdr(skb); |
b51655b9 | 171 | __sum16 csum = 0; |
422c346f PM |
172 | |
173 | switch (skb->ip_summed) { | |
84fa7933 | 174 | case CHECKSUM_COMPLETE: |
6e23ae2a | 175 | if (hook != NF_INET_PRE_ROUTING && hook != NF_INET_LOCAL_IN) |
422c346f | 176 | break; |
d3bc23e7 | 177 | if ((protocol == 0 && !csum_fold(skb->csum)) || |
422c346f | 178 | !csum_tcpudp_magic(iph->saddr, iph->daddr, |
e905a9ed | 179 | skb->len - dataoff, protocol, |
422c346f PM |
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 | } | |
422c346f PM |
196 | EXPORT_SYMBOL(nf_ip_checksum); |
197 | ||
d63a6507 PM |
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 | ||
1841a4c7 PM |
221 | static int nf_ip_route(struct dst_entry **dst, struct flowi *fl) |
222 | { | |
f206351a | 223 | return ip_route_output_key(&init_net, (struct rtable **)dst, fl); |
1841a4c7 PM |
224 | } |
225 | ||
1e796fda | 226 | static const struct nf_afinfo nf_ip_afinfo = { |
d63a6507 PM |
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), | |
2cc7d573 HW |
234 | }; |
235 | ||
65b4b4e8 | 236 | static int ipv4_netfilter_init(void) |
2cc7d573 | 237 | { |
bce8032e | 238 | return nf_register_afinfo(&nf_ip_afinfo); |
2cc7d573 HW |
239 | } |
240 | ||
65b4b4e8 | 241 | static void ipv4_netfilter_fini(void) |
2cc7d573 | 242 | { |
bce8032e | 243 | nf_unregister_afinfo(&nf_ip_afinfo); |
2cc7d573 HW |
244 | } |
245 | ||
65b4b4e8 AM |
246 | module_init(ipv4_netfilter_init); |
247 | module_exit(ipv4_netfilter_fini); | |
4f536522 PM |
248 | |
249 | #ifdef CONFIG_SYSCTL | |
250 | struct ctl_path nf_net_ipv4_netfilter_sysctl_path[] = { | |
f8572d8f EB |
251 | { .procname = "net", }, |
252 | { .procname = "ipv4", }, | |
253 | { .procname = "netfilter", }, | |
4f536522 PM |
254 | { } |
255 | }; | |
256 | EXPORT_SYMBOL_GPL(nf_net_ipv4_netfilter_sysctl_path); | |
257 | #endif /* CONFIG_SYSCTL */ |