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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> |
5a0e3ad6 | 7 | #include <linux/gfp.h> |
020b4c12 | 8 | #include <net/route.h> |
3e3850e9 PM |
9 | #include <net/xfrm.h> |
10 | #include <net/ip.h> | |
c01cd429 | 11 | #include <net/netfilter/nf_queue.h> |
020b4c12 HW |
12 | |
13 | /* route_me_harder function, used by iptable_nat, iptable_mangle + ip_queue */ | |
3db05fea | 14 | int ip_route_me_harder(struct sk_buff *skb, unsigned addr_type) |
020b4c12 | 15 | { |
adf30907 | 16 | struct net *net = dev_net(skb_dst(skb)->dev); |
3db05fea | 17 | const struct iphdr *iph = ip_hdr(skb); |
020b4c12 | 18 | struct rtable *rt; |
9d6ec938 | 19 | struct flowi4 fl4 = {}; |
ed6e4ef8 | 20 | __be32 saddr = iph->saddr; |
797fd391 | 21 | __u8 flags = skb->sk ? inet_sk_flowi_flags(skb->sk) : 0; |
020b4c12 HW |
22 | unsigned int hh_len; |
23 | ||
797fd391 JA |
24 | if (addr_type == RTN_UNSPEC) |
25 | addr_type = inet_addr_type(net, saddr); | |
26 | if (addr_type == RTN_LOCAL || addr_type == RTN_UNICAST) | |
27 | flags |= FLOWI_FLAG_ANYSRC; | |
28 | else | |
29 | saddr = 0; | |
b4c4ed17 | 30 | |
020b4c12 | 31 | /* some non-standard hacks like ipt_REJECT.c:send_reset() can cause |
6e23ae2a | 32 | * packets with foreign saddr to appear on the NF_INET_LOCAL_OUT hook. |
020b4c12 | 33 | */ |
ed6e4ef8 JA |
34 | fl4.daddr = iph->daddr; |
35 | fl4.saddr = saddr; | |
36 | fl4.flowi4_tos = RT_TOS(iph->tos); | |
37 | fl4.flowi4_oif = skb->sk ? skb->sk->sk_bound_dev_if : 0; | |
38 | fl4.flowi4_mark = skb->mark; | |
797fd391 | 39 | fl4.flowi4_flags = flags; |
ed6e4ef8 JA |
40 | rt = ip_route_output_key(net, &fl4); |
41 | if (IS_ERR(rt)) | |
42 | return -1; | |
020b4c12 | 43 | |
ed6e4ef8 JA |
44 | /* Drop old route. */ |
45 | skb_dst_drop(skb); | |
46 | skb_dst_set(skb, &rt->dst); | |
e905a9ed | 47 | |
adf30907 | 48 | if (skb_dst(skb)->error) |
020b4c12 HW |
49 | return -1; |
50 | ||
3e3850e9 | 51 | #ifdef CONFIG_XFRM |
3db05fea | 52 | if (!(IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) && |
9d6ec938 | 53 | xfrm_decode_session(skb, flowi4_to_flowi(&fl4), AF_INET) == 0) { |
adf30907 ED |
54 | struct dst_entry *dst = skb_dst(skb); |
55 | skb_dst_set(skb, NULL); | |
9d6ec938 | 56 | dst = xfrm_lookup(net, dst, flowi4_to_flowi(&fl4), skb->sk, 0); |
452edd59 | 57 | if (IS_ERR(dst)) |
3e3850e9 | 58 | return -1; |
adf30907 ED |
59 | skb_dst_set(skb, dst); |
60 | } | |
3e3850e9 PM |
61 | #endif |
62 | ||
020b4c12 | 63 | /* Change in oif may mean change in hh_len. */ |
adf30907 | 64 | hh_len = skb_dst(skb)->dev->hard_header_len; |
3db05fea HX |
65 | if (skb_headroom(skb) < hh_len && |
66 | pskb_expand_head(skb, hh_len - skb_headroom(skb), 0, GFP_ATOMIC)) | |
2ca7b0ac | 67 | return -1; |
020b4c12 HW |
68 | |
69 | return 0; | |
70 | } | |
71 | EXPORT_SYMBOL(ip_route_me_harder); | |
2cc7d573 | 72 | |
ee68cea2 | 73 | #ifdef CONFIG_XFRM |
3db05fea | 74 | int ip_xfrm_me_harder(struct sk_buff *skb) |
ee68cea2 PM |
75 | { |
76 | struct flowi fl; | |
77 | unsigned int hh_len; | |
78 | struct dst_entry *dst; | |
79 | ||
3db05fea | 80 | if (IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) |
ee68cea2 | 81 | return 0; |
3db05fea | 82 | if (xfrm_decode_session(skb, &fl, AF_INET) < 0) |
ee68cea2 PM |
83 | return -1; |
84 | ||
adf30907 | 85 | dst = skb_dst(skb); |
ee68cea2 PM |
86 | if (dst->xfrm) |
87 | dst = ((struct xfrm_dst *)dst)->route; | |
88 | dst_hold(dst); | |
89 | ||
452edd59 DM |
90 | dst = xfrm_lookup(dev_net(dst->dev), dst, &fl, skb->sk, 0); |
91 | if (IS_ERR(dst)) | |
ee68cea2 PM |
92 | return -1; |
93 | ||
adf30907 ED |
94 | skb_dst_drop(skb); |
95 | skb_dst_set(skb, dst); | |
ee68cea2 PM |
96 | |
97 | /* Change in oif may mean change in hh_len. */ | |
adf30907 | 98 | hh_len = skb_dst(skb)->dev->hard_header_len; |
3db05fea HX |
99 | if (skb_headroom(skb) < hh_len && |
100 | pskb_expand_head(skb, hh_len - skb_headroom(skb), 0, GFP_ATOMIC)) | |
2ca7b0ac | 101 | return -1; |
ee68cea2 PM |
102 | return 0; |
103 | } | |
104 | EXPORT_SYMBOL(ip_xfrm_me_harder); | |
105 | #endif | |
106 | ||
eb9c7ebe PM |
107 | void (*ip_nat_decode_session)(struct sk_buff *, struct flowi *); |
108 | EXPORT_SYMBOL(ip_nat_decode_session); | |
109 | ||
2cc7d573 HW |
110 | /* |
111 | * Extra routing may needed on local out, as the QUEUE target never | |
112 | * returns control to the table. | |
113 | */ | |
114 | ||
115 | struct ip_rt_info { | |
59b8bfd8 AV |
116 | __be32 daddr; |
117 | __be32 saddr; | |
2cc7d573 | 118 | u_int8_t tos; |
5f145e44 | 119 | u_int32_t mark; |
2cc7d573 HW |
120 | }; |
121 | ||
02f014d8 PM |
122 | static void nf_ip_saveroute(const struct sk_buff *skb, |
123 | struct nf_queue_entry *entry) | |
2cc7d573 | 124 | { |
02f014d8 | 125 | struct ip_rt_info *rt_info = nf_queue_entry_reroute(entry); |
2cc7d573 | 126 | |
02f014d8 | 127 | if (entry->hook == NF_INET_LOCAL_OUT) { |
eddc9ec5 | 128 | const struct iphdr *iph = ip_hdr(skb); |
2cc7d573 HW |
129 | |
130 | rt_info->tos = iph->tos; | |
131 | rt_info->daddr = iph->daddr; | |
132 | rt_info->saddr = iph->saddr; | |
5f145e44 | 133 | rt_info->mark = skb->mark; |
2cc7d573 HW |
134 | } |
135 | } | |
136 | ||
02f014d8 PM |
137 | static int nf_ip_reroute(struct sk_buff *skb, |
138 | const struct nf_queue_entry *entry) | |
2cc7d573 | 139 | { |
02f014d8 | 140 | const struct ip_rt_info *rt_info = nf_queue_entry_reroute(entry); |
2cc7d573 | 141 | |
02f014d8 | 142 | if (entry->hook == NF_INET_LOCAL_OUT) { |
3db05fea | 143 | const struct iphdr *iph = ip_hdr(skb); |
2cc7d573 | 144 | |
f64f9e71 JP |
145 | if (!(iph->tos == rt_info->tos && |
146 | skb->mark == rt_info->mark && | |
147 | iph->daddr == rt_info->daddr && | |
148 | iph->saddr == rt_info->saddr)) | |
3db05fea | 149 | return ip_route_me_harder(skb, RTN_UNSPEC); |
2cc7d573 HW |
150 | } |
151 | return 0; | |
152 | } | |
153 | ||
b51655b9 | 154 | __sum16 nf_ip_checksum(struct sk_buff *skb, unsigned int hook, |
422c346f PM |
155 | unsigned int dataoff, u_int8_t protocol) |
156 | { | |
eddc9ec5 | 157 | const struct iphdr *iph = ip_hdr(skb); |
b51655b9 | 158 | __sum16 csum = 0; |
422c346f PM |
159 | |
160 | switch (skb->ip_summed) { | |
84fa7933 | 161 | case CHECKSUM_COMPLETE: |
6e23ae2a | 162 | if (hook != NF_INET_PRE_ROUTING && hook != NF_INET_LOCAL_IN) |
422c346f | 163 | break; |
d3bc23e7 | 164 | if ((protocol == 0 && !csum_fold(skb->csum)) || |
422c346f | 165 | !csum_tcpudp_magic(iph->saddr, iph->daddr, |
e905a9ed | 166 | skb->len - dataoff, protocol, |
422c346f PM |
167 | skb->csum)) { |
168 | skb->ip_summed = CHECKSUM_UNNECESSARY; | |
169 | break; | |
170 | } | |
171 | /* fall through */ | |
172 | case CHECKSUM_NONE: | |
173 | if (protocol == 0) | |
174 | skb->csum = 0; | |
175 | else | |
176 | skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr, | |
177 | skb->len - dataoff, | |
178 | protocol, 0); | |
179 | csum = __skb_checksum_complete(skb); | |
180 | } | |
181 | return csum; | |
182 | } | |
422c346f PM |
183 | EXPORT_SYMBOL(nf_ip_checksum); |
184 | ||
d63a6507 PM |
185 | static __sum16 nf_ip_checksum_partial(struct sk_buff *skb, unsigned int hook, |
186 | unsigned int dataoff, unsigned int len, | |
187 | u_int8_t protocol) | |
188 | { | |
189 | const struct iphdr *iph = ip_hdr(skb); | |
190 | __sum16 csum = 0; | |
191 | ||
192 | switch (skb->ip_summed) { | |
193 | case CHECKSUM_COMPLETE: | |
194 | if (len == skb->len - dataoff) | |
195 | return nf_ip_checksum(skb, hook, dataoff, protocol); | |
196 | /* fall through */ | |
197 | case CHECKSUM_NONE: | |
198 | skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr, protocol, | |
199 | skb->len - dataoff, 0); | |
200 | skb->ip_summed = CHECKSUM_NONE; | |
c86ee67c | 201 | return __skb_checksum_complete_head(skb, dataoff + len); |
d63a6507 PM |
202 | } |
203 | return csum; | |
204 | } | |
205 | ||
31ad3dd6 | 206 | static int nf_ip_route(struct net *net, struct dst_entry **dst, |
0fae2e77 | 207 | struct flowi *fl, bool strict __always_unused) |
1841a4c7 | 208 | { |
31ad3dd6 | 209 | struct rtable *rt = ip_route_output_key(net, &fl->u.ip4); |
b23dd4fe DM |
210 | if (IS_ERR(rt)) |
211 | return PTR_ERR(rt); | |
212 | *dst = &rt->dst; | |
213 | return 0; | |
1841a4c7 PM |
214 | } |
215 | ||
1e796fda | 216 | static const struct nf_afinfo nf_ip_afinfo = { |
d63a6507 PM |
217 | .family = AF_INET, |
218 | .checksum = nf_ip_checksum, | |
219 | .checksum_partial = nf_ip_checksum_partial, | |
220 | .route = nf_ip_route, | |
221 | .saveroute = nf_ip_saveroute, | |
222 | .reroute = nf_ip_reroute, | |
223 | .route_key_size = sizeof(struct ip_rt_info), | |
2cc7d573 HW |
224 | }; |
225 | ||
65b4b4e8 | 226 | static int ipv4_netfilter_init(void) |
2cc7d573 | 227 | { |
bce8032e | 228 | return nf_register_afinfo(&nf_ip_afinfo); |
2cc7d573 HW |
229 | } |
230 | ||
65b4b4e8 | 231 | static void ipv4_netfilter_fini(void) |
2cc7d573 | 232 | { |
bce8032e | 233 | nf_unregister_afinfo(&nf_ip_afinfo); |
2cc7d573 HW |
234 | } |
235 | ||
65b4b4e8 AM |
236 | module_init(ipv4_netfilter_init); |
237 | module_exit(ipv4_netfilter_fini); | |
4f536522 PM |
238 | |
239 | #ifdef CONFIG_SYSCTL | |
240 | struct ctl_path nf_net_ipv4_netfilter_sysctl_path[] = { | |
f8572d8f EB |
241 | { .procname = "net", }, |
242 | { .procname = "ipv4", }, | |
243 | { .procname = "netfilter", }, | |
4f536522 PM |
244 | { } |
245 | }; | |
246 | EXPORT_SYMBOL_GPL(nf_net_ipv4_netfilter_sysctl_path); | |
247 | #endif /* CONFIG_SYSCTL */ |