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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> |
020b4c12 | 6 | #include <net/route.h> |
3e3850e9 PM |
7 | #include <net/xfrm.h> |
8 | #include <net/ip.h> | |
020b4c12 HW |
9 | |
10 | /* route_me_harder function, used by iptable_nat, iptable_mangle + ip_queue */ | |
b4c4ed17 | 11 | int ip_route_me_harder(struct sk_buff **pskb, unsigned addr_type) |
020b4c12 HW |
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 | ||
b4c4ed17 SH |
19 | if (addr_type == RTN_UNSPEC) |
20 | addr_type = inet_addr_type(iph->saddr); | |
21 | ||
020b4c12 HW |
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 | */ | |
b4c4ed17 | 25 | if (addr_type == RTN_LOCAL) { |
020b4c12 HW |
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; | |
47dcf0cb | 30 | fl.mark = (*pskb)->mark; |
020b4c12 HW |
31 | if (ip_route_output_key(&rt, &fl) != 0) |
32 | return -1; | |
33 | ||
34 | /* Drop old route. */ | |
35 | dst_release((*pskb)->dst); | |
36 | (*pskb)->dst = &rt->u.dst; | |
37 | } else { | |
38 | /* non-local src, find valid iif to satisfy | |
39 | * rp-filter when calling ip_route_input. */ | |
40 | fl.nl_u.ip4_u.daddr = iph->saddr; | |
41 | if (ip_route_output_key(&rt, &fl) != 0) | |
42 | return -1; | |
43 | ||
44 | odst = (*pskb)->dst; | |
45 | if (ip_route_input(*pskb, iph->daddr, iph->saddr, | |
46 | RT_TOS(iph->tos), rt->u.dst.dev) != 0) { | |
47 | dst_release(&rt->u.dst); | |
48 | return -1; | |
49 | } | |
50 | dst_release(&rt->u.dst); | |
51 | dst_release(odst); | |
52 | } | |
53 | ||
54 | if ((*pskb)->dst->error) | |
55 | return -1; | |
56 | ||
3e3850e9 PM |
57 | #ifdef CONFIG_XFRM |
58 | if (!(IPCB(*pskb)->flags & IPSKB_XFRM_TRANSFORMED) && | |
59 | xfrm_decode_session(*pskb, &fl, AF_INET) == 0) | |
60 | if (xfrm_lookup(&(*pskb)->dst, &fl, (*pskb)->sk, 0)) | |
61 | return -1; | |
62 | #endif | |
63 | ||
020b4c12 HW |
64 | /* Change in oif may mean change in hh_len. */ |
65 | hh_len = (*pskb)->dst->dev->hard_header_len; | |
66 | if (skb_headroom(*pskb) < hh_len) { | |
67 | struct sk_buff *nskb; | |
68 | ||
69 | nskb = skb_realloc_headroom(*pskb, hh_len); | |
70 | if (!nskb) | |
71 | return -1; | |
72 | if ((*pskb)->sk) | |
73 | skb_set_owner_w(nskb, (*pskb)->sk); | |
74 | kfree_skb(*pskb); | |
75 | *pskb = nskb; | |
76 | } | |
77 | ||
78 | return 0; | |
79 | } | |
80 | EXPORT_SYMBOL(ip_route_me_harder); | |
2cc7d573 | 81 | |
ee68cea2 PM |
82 | #ifdef CONFIG_XFRM |
83 | int ip_xfrm_me_harder(struct sk_buff **pskb) | |
84 | { | |
85 | struct flowi fl; | |
86 | unsigned int hh_len; | |
87 | struct dst_entry *dst; | |
88 | ||
89 | if (IPCB(*pskb)->flags & IPSKB_XFRM_TRANSFORMED) | |
90 | return 0; | |
91 | if (xfrm_decode_session(*pskb, &fl, AF_INET) < 0) | |
92 | return -1; | |
93 | ||
94 | dst = (*pskb)->dst; | |
95 | if (dst->xfrm) | |
96 | dst = ((struct xfrm_dst *)dst)->route; | |
97 | dst_hold(dst); | |
98 | ||
99 | if (xfrm_lookup(&dst, &fl, (*pskb)->sk, 0) < 0) | |
100 | return -1; | |
101 | ||
102 | dst_release((*pskb)->dst); | |
103 | (*pskb)->dst = dst; | |
104 | ||
105 | /* Change in oif may mean change in hh_len. */ | |
106 | hh_len = (*pskb)->dst->dev->hard_header_len; | |
107 | if (skb_headroom(*pskb) < hh_len) { | |
108 | struct sk_buff *nskb; | |
109 | ||
110 | nskb = skb_realloc_headroom(*pskb, hh_len); | |
111 | if (!nskb) | |
112 | return -1; | |
113 | if ((*pskb)->sk) | |
114 | skb_set_owner_w(nskb, (*pskb)->sk); | |
115 | kfree_skb(*pskb); | |
116 | *pskb = nskb; | |
117 | } | |
118 | return 0; | |
119 | } | |
120 | EXPORT_SYMBOL(ip_xfrm_me_harder); | |
121 | #endif | |
122 | ||
eb9c7ebe PM |
123 | void (*ip_nat_decode_session)(struct sk_buff *, struct flowi *); |
124 | EXPORT_SYMBOL(ip_nat_decode_session); | |
125 | ||
2cc7d573 HW |
126 | /* |
127 | * Extra routing may needed on local out, as the QUEUE target never | |
128 | * returns control to the table. | |
129 | */ | |
130 | ||
131 | struct ip_rt_info { | |
59b8bfd8 AV |
132 | __be32 daddr; |
133 | __be32 saddr; | |
2cc7d573 HW |
134 | u_int8_t tos; |
135 | }; | |
136 | ||
bce8032e | 137 | static void nf_ip_saveroute(const struct sk_buff *skb, struct nf_info *info) |
2cc7d573 HW |
138 | { |
139 | struct ip_rt_info *rt_info = nf_info_reroute(info); | |
140 | ||
141 | if (info->hook == NF_IP_LOCAL_OUT) { | |
142 | const struct iphdr *iph = skb->nh.iph; | |
143 | ||
144 | rt_info->tos = iph->tos; | |
145 | rt_info->daddr = iph->daddr; | |
146 | rt_info->saddr = iph->saddr; | |
147 | } | |
148 | } | |
149 | ||
bce8032e | 150 | static int nf_ip_reroute(struct sk_buff **pskb, const struct nf_info *info) |
2cc7d573 HW |
151 | { |
152 | const struct ip_rt_info *rt_info = nf_info_reroute(info); | |
153 | ||
154 | if (info->hook == NF_IP_LOCAL_OUT) { | |
155 | struct iphdr *iph = (*pskb)->nh.iph; | |
156 | ||
157 | if (!(iph->tos == rt_info->tos | |
158 | && iph->daddr == rt_info->daddr | |
159 | && iph->saddr == rt_info->saddr)) | |
b4c4ed17 | 160 | return ip_route_me_harder(pskb, RTN_UNSPEC); |
2cc7d573 HW |
161 | } |
162 | return 0; | |
163 | } | |
164 | ||
422c346f PM |
165 | unsigned int nf_ip_checksum(struct sk_buff *skb, unsigned int hook, |
166 | unsigned int dataoff, u_int8_t protocol) | |
167 | { | |
168 | struct iphdr *iph = skb->nh.iph; | |
169 | unsigned int csum = 0; | |
170 | ||
171 | switch (skb->ip_summed) { | |
84fa7933 | 172 | case CHECKSUM_COMPLETE: |
422c346f PM |
173 | if (hook != NF_IP_PRE_ROUTING && hook != NF_IP_LOCAL_IN) |
174 | break; | |
175 | if ((protocol == 0 && !(u16)csum_fold(skb->csum)) || | |
176 | !csum_tcpudp_magic(iph->saddr, iph->daddr, | |
177 | skb->len - dataoff, protocol, | |
178 | skb->csum)) { | |
179 | skb->ip_summed = CHECKSUM_UNNECESSARY; | |
180 | break; | |
181 | } | |
182 | /* fall through */ | |
183 | case CHECKSUM_NONE: | |
184 | if (protocol == 0) | |
185 | skb->csum = 0; | |
186 | else | |
187 | skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr, | |
188 | skb->len - dataoff, | |
189 | protocol, 0); | |
190 | csum = __skb_checksum_complete(skb); | |
191 | } | |
192 | return csum; | |
193 | } | |
194 | ||
195 | EXPORT_SYMBOL(nf_ip_checksum); | |
196 | ||
bce8032e PM |
197 | static struct nf_afinfo nf_ip_afinfo = { |
198 | .family = AF_INET, | |
422c346f | 199 | .checksum = nf_ip_checksum, |
bce8032e PM |
200 | .saveroute = nf_ip_saveroute, |
201 | .reroute = nf_ip_reroute, | |
202 | .route_key_size = sizeof(struct ip_rt_info), | |
2cc7d573 HW |
203 | }; |
204 | ||
65b4b4e8 | 205 | static int ipv4_netfilter_init(void) |
2cc7d573 | 206 | { |
bce8032e | 207 | return nf_register_afinfo(&nf_ip_afinfo); |
2cc7d573 HW |
208 | } |
209 | ||
65b4b4e8 | 210 | static void ipv4_netfilter_fini(void) |
2cc7d573 | 211 | { |
bce8032e | 212 | nf_unregister_afinfo(&nf_ip_afinfo); |
2cc7d573 HW |
213 | } |
214 | ||
65b4b4e8 AM |
215 | module_init(ipv4_netfilter_init); |
216 | module_exit(ipv4_netfilter_fini); |