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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 | 12 | { |
eddc9ec5 | 13 | const struct iphdr *iph = ip_hdr(*pskb); |
020b4c12 HW |
14 | struct rtable *rt; |
15 | struct flowi fl = {}; | |
16 | struct dst_entry *odst; | |
17 | unsigned int hh_len; | |
c68b8b68 | 18 | unsigned int type; |
020b4c12 | 19 | |
c68b8b68 | 20 | type = inet_addr_type(iph->saddr); |
b4c4ed17 | 21 | if (addr_type == RTN_UNSPEC) |
c68b8b68 | 22 | addr_type = type; |
b4c4ed17 | 23 | |
020b4c12 HW |
24 | /* some non-standard hacks like ipt_REJECT.c:send_reset() can cause |
25 | * packets with foreign saddr to appear on the NF_IP_LOCAL_OUT hook. | |
26 | */ | |
b4c4ed17 | 27 | if (addr_type == RTN_LOCAL) { |
020b4c12 | 28 | fl.nl_u.ip4_u.daddr = iph->daddr; |
c68b8b68 PM |
29 | if (type == RTN_LOCAL) |
30 | fl.nl_u.ip4_u.saddr = iph->saddr; | |
020b4c12 HW |
31 | fl.nl_u.ip4_u.tos = RT_TOS(iph->tos); |
32 | fl.oif = (*pskb)->sk ? (*pskb)->sk->sk_bound_dev_if : 0; | |
47dcf0cb | 33 | fl.mark = (*pskb)->mark; |
020b4c12 HW |
34 | if (ip_route_output_key(&rt, &fl) != 0) |
35 | return -1; | |
36 | ||
37 | /* Drop old route. */ | |
38 | dst_release((*pskb)->dst); | |
39 | (*pskb)->dst = &rt->u.dst; | |
40 | } else { | |
41 | /* non-local src, find valid iif to satisfy | |
42 | * rp-filter when calling ip_route_input. */ | |
43 | fl.nl_u.ip4_u.daddr = iph->saddr; | |
44 | if (ip_route_output_key(&rt, &fl) != 0) | |
45 | return -1; | |
46 | ||
47 | odst = (*pskb)->dst; | |
48 | if (ip_route_input(*pskb, iph->daddr, iph->saddr, | |
49 | RT_TOS(iph->tos), rt->u.dst.dev) != 0) { | |
50 | dst_release(&rt->u.dst); | |
51 | return -1; | |
52 | } | |
53 | dst_release(&rt->u.dst); | |
54 | dst_release(odst); | |
55 | } | |
e905a9ed | 56 | |
020b4c12 HW |
57 | if ((*pskb)->dst->error) |
58 | return -1; | |
59 | ||
3e3850e9 PM |
60 | #ifdef CONFIG_XFRM |
61 | if (!(IPCB(*pskb)->flags & IPSKB_XFRM_TRANSFORMED) && | |
62 | xfrm_decode_session(*pskb, &fl, AF_INET) == 0) | |
63 | if (xfrm_lookup(&(*pskb)->dst, &fl, (*pskb)->sk, 0)) | |
64 | return -1; | |
65 | #endif | |
66 | ||
020b4c12 HW |
67 | /* Change in oif may mean change in hh_len. */ |
68 | hh_len = (*pskb)->dst->dev->hard_header_len; | |
69 | if (skb_headroom(*pskb) < hh_len) { | |
70 | struct sk_buff *nskb; | |
71 | ||
72 | nskb = skb_realloc_headroom(*pskb, hh_len); | |
e905a9ed | 73 | if (!nskb) |
020b4c12 HW |
74 | return -1; |
75 | if ((*pskb)->sk) | |
76 | skb_set_owner_w(nskb, (*pskb)->sk); | |
77 | kfree_skb(*pskb); | |
78 | *pskb = nskb; | |
79 | } | |
80 | ||
81 | return 0; | |
82 | } | |
83 | EXPORT_SYMBOL(ip_route_me_harder); | |
2cc7d573 | 84 | |
ee68cea2 PM |
85 | #ifdef CONFIG_XFRM |
86 | int ip_xfrm_me_harder(struct sk_buff **pskb) | |
87 | { | |
88 | struct flowi fl; | |
89 | unsigned int hh_len; | |
90 | struct dst_entry *dst; | |
91 | ||
92 | if (IPCB(*pskb)->flags & IPSKB_XFRM_TRANSFORMED) | |
93 | return 0; | |
94 | if (xfrm_decode_session(*pskb, &fl, AF_INET) < 0) | |
95 | return -1; | |
96 | ||
97 | dst = (*pskb)->dst; | |
98 | if (dst->xfrm) | |
99 | dst = ((struct xfrm_dst *)dst)->route; | |
100 | dst_hold(dst); | |
101 | ||
102 | if (xfrm_lookup(&dst, &fl, (*pskb)->sk, 0) < 0) | |
103 | return -1; | |
104 | ||
105 | dst_release((*pskb)->dst); | |
106 | (*pskb)->dst = dst; | |
107 | ||
108 | /* Change in oif may mean change in hh_len. */ | |
109 | hh_len = (*pskb)->dst->dev->hard_header_len; | |
110 | if (skb_headroom(*pskb) < hh_len) { | |
111 | struct sk_buff *nskb; | |
112 | ||
113 | nskb = skb_realloc_headroom(*pskb, hh_len); | |
114 | if (!nskb) | |
115 | return -1; | |
116 | if ((*pskb)->sk) | |
117 | skb_set_owner_w(nskb, (*pskb)->sk); | |
118 | kfree_skb(*pskb); | |
119 | *pskb = nskb; | |
120 | } | |
121 | return 0; | |
122 | } | |
123 | EXPORT_SYMBOL(ip_xfrm_me_harder); | |
124 | #endif | |
125 | ||
eb9c7ebe PM |
126 | void (*ip_nat_decode_session)(struct sk_buff *, struct flowi *); |
127 | EXPORT_SYMBOL(ip_nat_decode_session); | |
128 | ||
2cc7d573 HW |
129 | /* |
130 | * Extra routing may needed on local out, as the QUEUE target never | |
131 | * returns control to the table. | |
132 | */ | |
133 | ||
134 | struct ip_rt_info { | |
59b8bfd8 AV |
135 | __be32 daddr; |
136 | __be32 saddr; | |
2cc7d573 HW |
137 | u_int8_t tos; |
138 | }; | |
139 | ||
bce8032e | 140 | static void nf_ip_saveroute(const struct sk_buff *skb, struct nf_info *info) |
2cc7d573 HW |
141 | { |
142 | struct ip_rt_info *rt_info = nf_info_reroute(info); | |
143 | ||
144 | if (info->hook == NF_IP_LOCAL_OUT) { | |
eddc9ec5 | 145 | const struct iphdr *iph = ip_hdr(skb); |
2cc7d573 HW |
146 | |
147 | rt_info->tos = iph->tos; | |
148 | rt_info->daddr = iph->daddr; | |
149 | rt_info->saddr = iph->saddr; | |
150 | } | |
151 | } | |
152 | ||
bce8032e | 153 | static int nf_ip_reroute(struct sk_buff **pskb, const struct nf_info *info) |
2cc7d573 HW |
154 | { |
155 | const struct ip_rt_info *rt_info = nf_info_reroute(info); | |
156 | ||
157 | if (info->hook == NF_IP_LOCAL_OUT) { | |
eddc9ec5 | 158 | const struct iphdr *iph = ip_hdr(*pskb); |
2cc7d573 HW |
159 | |
160 | if (!(iph->tos == rt_info->tos | |
161 | && iph->daddr == rt_info->daddr | |
162 | && iph->saddr == rt_info->saddr)) | |
b4c4ed17 | 163 | return ip_route_me_harder(pskb, RTN_UNSPEC); |
2cc7d573 HW |
164 | } |
165 | return 0; | |
166 | } | |
167 | ||
b51655b9 | 168 | __sum16 nf_ip_checksum(struct sk_buff *skb, unsigned int hook, |
422c346f PM |
169 | unsigned int dataoff, u_int8_t protocol) |
170 | { | |
eddc9ec5 | 171 | const struct iphdr *iph = ip_hdr(skb); |
b51655b9 | 172 | __sum16 csum = 0; |
422c346f PM |
173 | |
174 | switch (skb->ip_summed) { | |
84fa7933 | 175 | case CHECKSUM_COMPLETE: |
422c346f PM |
176 | if (hook != NF_IP_PRE_ROUTING && hook != NF_IP_LOCAL_IN) |
177 | break; | |
d3bc23e7 | 178 | if ((protocol == 0 && !csum_fold(skb->csum)) || |
422c346f | 179 | !csum_tcpudp_magic(iph->saddr, iph->daddr, |
e905a9ed | 180 | skb->len - dataoff, protocol, |
422c346f PM |
181 | skb->csum)) { |
182 | skb->ip_summed = CHECKSUM_UNNECESSARY; | |
183 | break; | |
184 | } | |
185 | /* fall through */ | |
186 | case CHECKSUM_NONE: | |
187 | if (protocol == 0) | |
188 | skb->csum = 0; | |
189 | else | |
190 | skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr, | |
191 | skb->len - dataoff, | |
192 | protocol, 0); | |
193 | csum = __skb_checksum_complete(skb); | |
194 | } | |
195 | return csum; | |
196 | } | |
197 | ||
198 | EXPORT_SYMBOL(nf_ip_checksum); | |
199 | ||
bce8032e PM |
200 | static struct nf_afinfo nf_ip_afinfo = { |
201 | .family = AF_INET, | |
422c346f | 202 | .checksum = nf_ip_checksum, |
bce8032e PM |
203 | .saveroute = nf_ip_saveroute, |
204 | .reroute = nf_ip_reroute, | |
205 | .route_key_size = sizeof(struct ip_rt_info), | |
2cc7d573 HW |
206 | }; |
207 | ||
65b4b4e8 | 208 | static int ipv4_netfilter_init(void) |
2cc7d573 | 209 | { |
bce8032e | 210 | return nf_register_afinfo(&nf_ip_afinfo); |
2cc7d573 HW |
211 | } |
212 | ||
65b4b4e8 | 213 | static void ipv4_netfilter_fini(void) |
2cc7d573 | 214 | { |
bce8032e | 215 | nf_unregister_afinfo(&nf_ip_afinfo); |
2cc7d573 HW |
216 | } |
217 | ||
65b4b4e8 AM |
218 | module_init(ipv4_netfilter_init); |
219 | module_exit(ipv4_netfilter_fini); |