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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> |
bc3b2d7f | 8 | #include <linux/export.h> |
020b4c12 | 9 | #include <net/route.h> |
3e3850e9 PM |
10 | #include <net/xfrm.h> |
11 | #include <net/ip.h> | |
c01cd429 | 12 | #include <net/netfilter/nf_queue.h> |
020b4c12 HW |
13 | |
14 | /* route_me_harder function, used by iptable_nat, iptable_mangle + ip_queue */ | |
95c96174 | 15 | int ip_route_me_harder(struct sk_buff *skb, unsigned int addr_type) |
020b4c12 | 16 | { |
adf30907 | 17 | struct net *net = dev_net(skb_dst(skb)->dev); |
3db05fea | 18 | const struct iphdr *iph = ip_hdr(skb); |
020b4c12 | 19 | struct rtable *rt; |
9d6ec938 | 20 | struct flowi4 fl4 = {}; |
ed6e4ef8 | 21 | __be32 saddr = iph->saddr; |
797fd391 | 22 | __u8 flags = skb->sk ? inet_sk_flowi_flags(skb->sk) : 0; |
020b4c12 HW |
23 | unsigned int hh_len; |
24 | ||
797fd391 JA |
25 | if (addr_type == RTN_UNSPEC) |
26 | addr_type = inet_addr_type(net, saddr); | |
27 | if (addr_type == RTN_LOCAL || addr_type == RTN_UNICAST) | |
28 | flags |= FLOWI_FLAG_ANYSRC; | |
29 | else | |
30 | saddr = 0; | |
b4c4ed17 | 31 | |
020b4c12 | 32 | /* some non-standard hacks like ipt_REJECT.c:send_reset() can cause |
6e23ae2a | 33 | * packets with foreign saddr to appear on the NF_INET_LOCAL_OUT hook. |
020b4c12 | 34 | */ |
ed6e4ef8 JA |
35 | fl4.daddr = iph->daddr; |
36 | fl4.saddr = saddr; | |
37 | fl4.flowi4_tos = RT_TOS(iph->tos); | |
38 | fl4.flowi4_oif = skb->sk ? skb->sk->sk_bound_dev_if : 0; | |
39 | fl4.flowi4_mark = skb->mark; | |
797fd391 | 40 | fl4.flowi4_flags = flags; |
ed6e4ef8 JA |
41 | rt = ip_route_output_key(net, &fl4); |
42 | if (IS_ERR(rt)) | |
43 | return -1; | |
020b4c12 | 44 | |
ed6e4ef8 JA |
45 | /* Drop old route. */ |
46 | skb_dst_drop(skb); | |
47 | skb_dst_set(skb, &rt->dst); | |
e905a9ed | 48 | |
adf30907 | 49 | if (skb_dst(skb)->error) |
020b4c12 HW |
50 | return -1; |
51 | ||
3e3850e9 | 52 | #ifdef CONFIG_XFRM |
3db05fea | 53 | if (!(IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) && |
9d6ec938 | 54 | xfrm_decode_session(skb, flowi4_to_flowi(&fl4), AF_INET) == 0) { |
adf30907 ED |
55 | struct dst_entry *dst = skb_dst(skb); |
56 | skb_dst_set(skb, NULL); | |
9d6ec938 | 57 | dst = xfrm_lookup(net, dst, flowi4_to_flowi(&fl4), skb->sk, 0); |
452edd59 | 58 | if (IS_ERR(dst)) |
3e3850e9 | 59 | return -1; |
adf30907 ED |
60 | skb_dst_set(skb, dst); |
61 | } | |
3e3850e9 PM |
62 | #endif |
63 | ||
020b4c12 | 64 | /* Change in oif may mean change in hh_len. */ |
adf30907 | 65 | hh_len = skb_dst(skb)->dev->hard_header_len; |
3db05fea | 66 | if (skb_headroom(skb) < hh_len && |
5e2afba4 PG |
67 | pskb_expand_head(skb, HH_DATA_ALIGN(hh_len - skb_headroom(skb)), |
68 | 0, GFP_ATOMIC)) | |
2ca7b0ac | 69 | return -1; |
020b4c12 HW |
70 | |
71 | return 0; | |
72 | } | |
73 | EXPORT_SYMBOL(ip_route_me_harder); | |
2cc7d573 HW |
74 | |
75 | /* | |
76 | * Extra routing may needed on local out, as the QUEUE target never | |
77 | * returns control to the table. | |
78 | */ | |
79 | ||
80 | struct ip_rt_info { | |
59b8bfd8 AV |
81 | __be32 daddr; |
82 | __be32 saddr; | |
2cc7d573 | 83 | u_int8_t tos; |
5f145e44 | 84 | u_int32_t mark; |
2cc7d573 HW |
85 | }; |
86 | ||
02f014d8 PM |
87 | static void nf_ip_saveroute(const struct sk_buff *skb, |
88 | struct nf_queue_entry *entry) | |
2cc7d573 | 89 | { |
02f014d8 | 90 | struct ip_rt_info *rt_info = nf_queue_entry_reroute(entry); |
2cc7d573 | 91 | |
02f014d8 | 92 | if (entry->hook == NF_INET_LOCAL_OUT) { |
eddc9ec5 | 93 | const struct iphdr *iph = ip_hdr(skb); |
2cc7d573 HW |
94 | |
95 | rt_info->tos = iph->tos; | |
96 | rt_info->daddr = iph->daddr; | |
97 | rt_info->saddr = iph->saddr; | |
5f145e44 | 98 | rt_info->mark = skb->mark; |
2cc7d573 HW |
99 | } |
100 | } | |
101 | ||
02f014d8 PM |
102 | static int nf_ip_reroute(struct sk_buff *skb, |
103 | const struct nf_queue_entry *entry) | |
2cc7d573 | 104 | { |
02f014d8 | 105 | const struct ip_rt_info *rt_info = nf_queue_entry_reroute(entry); |
2cc7d573 | 106 | |
02f014d8 | 107 | if (entry->hook == NF_INET_LOCAL_OUT) { |
3db05fea | 108 | const struct iphdr *iph = ip_hdr(skb); |
2cc7d573 | 109 | |
f64f9e71 JP |
110 | if (!(iph->tos == rt_info->tos && |
111 | skb->mark == rt_info->mark && | |
112 | iph->daddr == rt_info->daddr && | |
113 | iph->saddr == rt_info->saddr)) | |
3db05fea | 114 | return ip_route_me_harder(skb, RTN_UNSPEC); |
2cc7d573 HW |
115 | } |
116 | return 0; | |
117 | } | |
118 | ||
b51655b9 | 119 | __sum16 nf_ip_checksum(struct sk_buff *skb, unsigned int hook, |
422c346f PM |
120 | unsigned int dataoff, u_int8_t protocol) |
121 | { | |
eddc9ec5 | 122 | const struct iphdr *iph = ip_hdr(skb); |
b51655b9 | 123 | __sum16 csum = 0; |
422c346f PM |
124 | |
125 | switch (skb->ip_summed) { | |
84fa7933 | 126 | case CHECKSUM_COMPLETE: |
6e23ae2a | 127 | if (hook != NF_INET_PRE_ROUTING && hook != NF_INET_LOCAL_IN) |
422c346f | 128 | break; |
d3bc23e7 | 129 | if ((protocol == 0 && !csum_fold(skb->csum)) || |
422c346f | 130 | !csum_tcpudp_magic(iph->saddr, iph->daddr, |
e905a9ed | 131 | skb->len - dataoff, protocol, |
422c346f PM |
132 | skb->csum)) { |
133 | skb->ip_summed = CHECKSUM_UNNECESSARY; | |
134 | break; | |
135 | } | |
136 | /* fall through */ | |
137 | case CHECKSUM_NONE: | |
138 | if (protocol == 0) | |
139 | skb->csum = 0; | |
140 | else | |
141 | skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr, | |
142 | skb->len - dataoff, | |
143 | protocol, 0); | |
144 | csum = __skb_checksum_complete(skb); | |
145 | } | |
146 | return csum; | |
147 | } | |
422c346f PM |
148 | EXPORT_SYMBOL(nf_ip_checksum); |
149 | ||
d63a6507 PM |
150 | static __sum16 nf_ip_checksum_partial(struct sk_buff *skb, unsigned int hook, |
151 | unsigned int dataoff, unsigned int len, | |
152 | u_int8_t protocol) | |
153 | { | |
154 | const struct iphdr *iph = ip_hdr(skb); | |
155 | __sum16 csum = 0; | |
156 | ||
157 | switch (skb->ip_summed) { | |
158 | case CHECKSUM_COMPLETE: | |
159 | if (len == skb->len - dataoff) | |
160 | return nf_ip_checksum(skb, hook, dataoff, protocol); | |
161 | /* fall through */ | |
162 | case CHECKSUM_NONE: | |
163 | skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr, protocol, | |
164 | skb->len - dataoff, 0); | |
165 | skb->ip_summed = CHECKSUM_NONE; | |
c86ee67c | 166 | return __skb_checksum_complete_head(skb, dataoff + len); |
d63a6507 PM |
167 | } |
168 | return csum; | |
169 | } | |
170 | ||
31ad3dd6 | 171 | static int nf_ip_route(struct net *net, struct dst_entry **dst, |
0fae2e77 | 172 | struct flowi *fl, bool strict __always_unused) |
1841a4c7 | 173 | { |
31ad3dd6 | 174 | struct rtable *rt = ip_route_output_key(net, &fl->u.ip4); |
b23dd4fe DM |
175 | if (IS_ERR(rt)) |
176 | return PTR_ERR(rt); | |
177 | *dst = &rt->dst; | |
178 | return 0; | |
1841a4c7 PM |
179 | } |
180 | ||
1e796fda | 181 | static const struct nf_afinfo nf_ip_afinfo = { |
d63a6507 PM |
182 | .family = AF_INET, |
183 | .checksum = nf_ip_checksum, | |
184 | .checksum_partial = nf_ip_checksum_partial, | |
185 | .route = nf_ip_route, | |
186 | .saveroute = nf_ip_saveroute, | |
187 | .reroute = nf_ip_reroute, | |
188 | .route_key_size = sizeof(struct ip_rt_info), | |
2cc7d573 HW |
189 | }; |
190 | ||
ce9f3f31 | 191 | static int __init ipv4_netfilter_init(void) |
2cc7d573 | 192 | { |
bce8032e | 193 | return nf_register_afinfo(&nf_ip_afinfo); |
2cc7d573 HW |
194 | } |
195 | ||
ce9f3f31 | 196 | static void __exit ipv4_netfilter_fini(void) |
2cc7d573 | 197 | { |
bce8032e | 198 | nf_unregister_afinfo(&nf_ip_afinfo); |
2cc7d573 HW |
199 | } |
200 | ||
65b4b4e8 AM |
201 | module_init(ipv4_netfilter_init); |
202 | module_exit(ipv4_netfilter_fini); |