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1/*
2 * IPv4 specific functions of netfilter core
3 *
4 * Rusty Russell (C) 2000 -- This code is GPL.
5 * Patrick McHardy (C) 2006-2012
6 */
7#include <linux/kernel.h>
8#include <linux/netfilter.h>
9#include <linux/netfilter_ipv4.h>
10#include <linux/ip.h>
11#include <linux/skbuff.h>
12#include <linux/gfp.h>
13#include <linux/export.h>
14#include <net/route.h>
15#include <net/xfrm.h>
16#include <net/ip.h>
17#include <net/netfilter/nf_queue.h>
18
19/* route_me_harder function, used by iptable_nat, iptable_mangle + ip_queue */
20int ip_route_me_harder(struct net *net, struct sk_buff *skb, unsigned int addr_type)
21{
22 const struct iphdr *iph = ip_hdr(skb);
23 struct rtable *rt;
24 struct flowi4 fl4 = {};
25 __be32 saddr = iph->saddr;
26 __u8 flags = skb->sk ? inet_sk_flowi_flags(skb->sk) : 0;
27 unsigned int hh_len;
28
29 if (addr_type == RTN_UNSPEC)
30 addr_type = inet_addr_type(net, saddr);
31 if (addr_type == RTN_LOCAL || addr_type == RTN_UNICAST)
32 flags |= FLOWI_FLAG_ANYSRC;
33 else
34 saddr = 0;
35
36 /* some non-standard hacks like ipt_REJECT.c:send_reset() can cause
37 * packets with foreign saddr to appear on the NF_INET_LOCAL_OUT hook.
38 */
39 fl4.daddr = iph->daddr;
40 fl4.saddr = saddr;
41 fl4.flowi4_tos = RT_TOS(iph->tos);
42 fl4.flowi4_oif = skb->sk ? skb->sk->sk_bound_dev_if : 0;
43 fl4.flowi4_mark = skb->mark;
44 fl4.flowi4_flags = flags;
45 rt = ip_route_output_key(net, &fl4);
46 if (IS_ERR(rt))
47 return PTR_ERR(rt);
48
49 /* Drop old route. */
50 skb_dst_drop(skb);
51 skb_dst_set(skb, &rt->dst);
52
53 if (skb_dst(skb)->error)
54 return skb_dst(skb)->error;
55
56#ifdef CONFIG_XFRM
57 if (!(IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) &&
58 xfrm_decode_session(skb, flowi4_to_flowi(&fl4), AF_INET) == 0) {
59 struct dst_entry *dst = skb_dst(skb);
60 skb_dst_set(skb, NULL);
61 dst = xfrm_lookup(net, dst, flowi4_to_flowi(&fl4), skb->sk, 0);
62 if (IS_ERR(dst))
63 return PTR_ERR(dst);
64 skb_dst_set(skb, dst);
65 }
66#endif
67
68 /* Change in oif may mean change in hh_len. */
69 hh_len = skb_dst(skb)->dev->hard_header_len;
70 if (skb_headroom(skb) < hh_len &&
71 pskb_expand_head(skb, HH_DATA_ALIGN(hh_len - skb_headroom(skb)),
72 0, GFP_ATOMIC))
73 return -ENOMEM;
74
75 return 0;
76}
77EXPORT_SYMBOL(ip_route_me_harder);
78
79/*
80 * Extra routing may needed on local out, as the QUEUE target never
81 * returns control to the table.
82 */
83
84struct ip_rt_info {
85 __be32 daddr;
86 __be32 saddr;
87 u_int8_t tos;
88 u_int32_t mark;
89};
90
91static void nf_ip_saveroute(const struct sk_buff *skb,
92 struct nf_queue_entry *entry)
93{
94 struct ip_rt_info *rt_info = nf_queue_entry_reroute(entry);
95
96 if (entry->state.hook == NF_INET_LOCAL_OUT) {
97 const struct iphdr *iph = ip_hdr(skb);
98
99 rt_info->tos = iph->tos;
100 rt_info->daddr = iph->daddr;
101 rt_info->saddr = iph->saddr;
102 rt_info->mark = skb->mark;
103 }
104}
105
106static int nf_ip_reroute(struct net *net, struct sk_buff *skb,
107 const struct nf_queue_entry *entry)
108{
109 const struct ip_rt_info *rt_info = nf_queue_entry_reroute(entry);
110
111 if (entry->state.hook == NF_INET_LOCAL_OUT) {
112 const struct iphdr *iph = ip_hdr(skb);
113
114 if (!(iph->tos == rt_info->tos &&
115 skb->mark == rt_info->mark &&
116 iph->daddr == rt_info->daddr &&
117 iph->saddr == rt_info->saddr))
118 return ip_route_me_harder(net, skb, RTN_UNSPEC);
119 }
120 return 0;
121}
122
123__sum16 nf_ip_checksum(struct sk_buff *skb, unsigned int hook,
124 unsigned int dataoff, u_int8_t protocol)
125{
126 const struct iphdr *iph = ip_hdr(skb);
127 __sum16 csum = 0;
128
129 switch (skb->ip_summed) {
130 case CHECKSUM_COMPLETE:
131 if (hook != NF_INET_PRE_ROUTING && hook != NF_INET_LOCAL_IN)
132 break;
133 if ((protocol == 0 && !csum_fold(skb->csum)) ||
134 !csum_tcpudp_magic(iph->saddr, iph->daddr,
135 skb->len - dataoff, protocol,
136 skb->csum)) {
137 skb->ip_summed = CHECKSUM_UNNECESSARY;
138 break;
139 }
140 /* fall through */
141 case CHECKSUM_NONE:
142 if (protocol == 0)
143 skb->csum = 0;
144 else
145 skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr,
146 skb->len - dataoff,
147 protocol, 0);
148 csum = __skb_checksum_complete(skb);
149 }
150 return csum;
151}
152EXPORT_SYMBOL(nf_ip_checksum);
153
154static __sum16 nf_ip_checksum_partial(struct sk_buff *skb, unsigned int hook,
155 unsigned int dataoff, unsigned int len,
156 u_int8_t protocol)
157{
158 const struct iphdr *iph = ip_hdr(skb);
159 __sum16 csum = 0;
160
161 switch (skb->ip_summed) {
162 case CHECKSUM_COMPLETE:
163 if (len == skb->len - dataoff)
164 return nf_ip_checksum(skb, hook, dataoff, protocol);
165 /* fall through */
166 case CHECKSUM_NONE:
167 skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr, protocol,
168 skb->len - dataoff, 0);
169 skb->ip_summed = CHECKSUM_NONE;
170 return __skb_checksum_complete_head(skb, dataoff + len);
171 }
172 return csum;
173}
174
175static int nf_ip_route(struct net *net, struct dst_entry **dst,
176 struct flowi *fl, bool strict __always_unused)
177{
178 struct rtable *rt = ip_route_output_key(net, &fl->u.ip4);
179 if (IS_ERR(rt))
180 return PTR_ERR(rt);
181 *dst = &rt->dst;
182 return 0;
183}
184
185static const struct nf_afinfo nf_ip_afinfo = {
186 .family = AF_INET,
187 .checksum = nf_ip_checksum,
188 .checksum_partial = nf_ip_checksum_partial,
189 .route = nf_ip_route,
190 .saveroute = nf_ip_saveroute,
191 .reroute = nf_ip_reroute,
192 .route_key_size = sizeof(struct ip_rt_info),
193};
194
195static int __init ipv4_netfilter_init(void)
196{
197 return nf_register_afinfo(&nf_ip_afinfo);
198}
199subsys_initcall(ipv4_netfilter_init);
1/* IPv4 specific functions of netfilter core */
2#include <linux/kernel.h>
3#include <linux/netfilter.h>
4#include <linux/netfilter_ipv4.h>
5#include <linux/ip.h>
6#include <linux/skbuff.h>
7#include <linux/gfp.h>
8#include <linux/export.h>
9#include <net/route.h>
10#include <net/xfrm.h>
11#include <net/ip.h>
12#include <net/netfilter/nf_queue.h>
13
14/* route_me_harder function, used by iptable_nat, iptable_mangle + ip_queue */
15int ip_route_me_harder(struct sk_buff *skb, unsigned int addr_type)
16{
17 struct net *net = dev_net(skb_dst(skb)->dev);
18 const struct iphdr *iph = ip_hdr(skb);
19 struct rtable *rt;
20 struct flowi4 fl4 = {};
21 __be32 saddr = iph->saddr;
22 __u8 flags = skb->sk ? inet_sk_flowi_flags(skb->sk) : 0;
23 unsigned int hh_len;
24
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;
31
32 /* some non-standard hacks like ipt_REJECT.c:send_reset() can cause
33 * packets with foreign saddr to appear on the NF_INET_LOCAL_OUT hook.
34 */
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;
40 fl4.flowi4_flags = flags;
41 rt = ip_route_output_key(net, &fl4);
42 if (IS_ERR(rt))
43 return -1;
44
45 /* Drop old route. */
46 skb_dst_drop(skb);
47 skb_dst_set(skb, &rt->dst);
48
49 if (skb_dst(skb)->error)
50 return -1;
51
52#ifdef CONFIG_XFRM
53 if (!(IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) &&
54 xfrm_decode_session(skb, flowi4_to_flowi(&fl4), AF_INET) == 0) {
55 struct dst_entry *dst = skb_dst(skb);
56 skb_dst_set(skb, NULL);
57 dst = xfrm_lookup(net, dst, flowi4_to_flowi(&fl4), skb->sk, 0);
58 if (IS_ERR(dst))
59 return -1;
60 skb_dst_set(skb, dst);
61 }
62#endif
63
64 /* Change in oif may mean change in hh_len. */
65 hh_len = skb_dst(skb)->dev->hard_header_len;
66 if (skb_headroom(skb) < hh_len &&
67 pskb_expand_head(skb, HH_DATA_ALIGN(hh_len - skb_headroom(skb)),
68 0, GFP_ATOMIC))
69 return -1;
70
71 return 0;
72}
73EXPORT_SYMBOL(ip_route_me_harder);
74
75#ifdef CONFIG_XFRM
76int ip_xfrm_me_harder(struct sk_buff *skb)
77{
78 struct flowi fl;
79 unsigned int hh_len;
80 struct dst_entry *dst;
81
82 if (IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED)
83 return 0;
84 if (xfrm_decode_session(skb, &fl, AF_INET) < 0)
85 return -1;
86
87 dst = skb_dst(skb);
88 if (dst->xfrm)
89 dst = ((struct xfrm_dst *)dst)->route;
90 dst_hold(dst);
91
92 dst = xfrm_lookup(dev_net(dst->dev), dst, &fl, skb->sk, 0);
93 if (IS_ERR(dst))
94 return -1;
95
96 skb_dst_drop(skb);
97 skb_dst_set(skb, dst);
98
99 /* Change in oif may mean change in hh_len. */
100 hh_len = skb_dst(skb)->dev->hard_header_len;
101 if (skb_headroom(skb) < hh_len &&
102 pskb_expand_head(skb, hh_len - skb_headroom(skb), 0, GFP_ATOMIC))
103 return -1;
104 return 0;
105}
106EXPORT_SYMBOL(ip_xfrm_me_harder);
107#endif
108
109void (*ip_nat_decode_session)(struct sk_buff *, struct flowi *);
110EXPORT_SYMBOL(ip_nat_decode_session);
111
112/*
113 * Extra routing may needed on local out, as the QUEUE target never
114 * returns control to the table.
115 */
116
117struct ip_rt_info {
118 __be32 daddr;
119 __be32 saddr;
120 u_int8_t tos;
121 u_int32_t mark;
122};
123
124static void nf_ip_saveroute(const struct sk_buff *skb,
125 struct nf_queue_entry *entry)
126{
127 struct ip_rt_info *rt_info = nf_queue_entry_reroute(entry);
128
129 if (entry->hook == NF_INET_LOCAL_OUT) {
130 const struct iphdr *iph = ip_hdr(skb);
131
132 rt_info->tos = iph->tos;
133 rt_info->daddr = iph->daddr;
134 rt_info->saddr = iph->saddr;
135 rt_info->mark = skb->mark;
136 }
137}
138
139static int nf_ip_reroute(struct sk_buff *skb,
140 const struct nf_queue_entry *entry)
141{
142 const struct ip_rt_info *rt_info = nf_queue_entry_reroute(entry);
143
144 if (entry->hook == NF_INET_LOCAL_OUT) {
145 const struct iphdr *iph = ip_hdr(skb);
146
147 if (!(iph->tos == rt_info->tos &&
148 skb->mark == rt_info->mark &&
149 iph->daddr == rt_info->daddr &&
150 iph->saddr == rt_info->saddr))
151 return ip_route_me_harder(skb, RTN_UNSPEC);
152 }
153 return 0;
154}
155
156__sum16 nf_ip_checksum(struct sk_buff *skb, unsigned int hook,
157 unsigned int dataoff, u_int8_t protocol)
158{
159 const struct iphdr *iph = ip_hdr(skb);
160 __sum16 csum = 0;
161
162 switch (skb->ip_summed) {
163 case CHECKSUM_COMPLETE:
164 if (hook != NF_INET_PRE_ROUTING && hook != NF_INET_LOCAL_IN)
165 break;
166 if ((protocol == 0 && !csum_fold(skb->csum)) ||
167 !csum_tcpudp_magic(iph->saddr, iph->daddr,
168 skb->len - dataoff, protocol,
169 skb->csum)) {
170 skb->ip_summed = CHECKSUM_UNNECESSARY;
171 break;
172 }
173 /* fall through */
174 case CHECKSUM_NONE:
175 if (protocol == 0)
176 skb->csum = 0;
177 else
178 skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr,
179 skb->len - dataoff,
180 protocol, 0);
181 csum = __skb_checksum_complete(skb);
182 }
183 return csum;
184}
185EXPORT_SYMBOL(nf_ip_checksum);
186
187static __sum16 nf_ip_checksum_partial(struct sk_buff *skb, unsigned int hook,
188 unsigned int dataoff, unsigned int len,
189 u_int8_t protocol)
190{
191 const struct iphdr *iph = ip_hdr(skb);
192 __sum16 csum = 0;
193
194 switch (skb->ip_summed) {
195 case CHECKSUM_COMPLETE:
196 if (len == skb->len - dataoff)
197 return nf_ip_checksum(skb, hook, dataoff, protocol);
198 /* fall through */
199 case CHECKSUM_NONE:
200 skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr, protocol,
201 skb->len - dataoff, 0);
202 skb->ip_summed = CHECKSUM_NONE;
203 return __skb_checksum_complete_head(skb, dataoff + len);
204 }
205 return csum;
206}
207
208static int nf_ip_route(struct net *net, struct dst_entry **dst,
209 struct flowi *fl, bool strict __always_unused)
210{
211 struct rtable *rt = ip_route_output_key(net, &fl->u.ip4);
212 if (IS_ERR(rt))
213 return PTR_ERR(rt);
214 *dst = &rt->dst;
215 return 0;
216}
217
218static const struct nf_afinfo nf_ip_afinfo = {
219 .family = AF_INET,
220 .checksum = nf_ip_checksum,
221 .checksum_partial = nf_ip_checksum_partial,
222 .route = nf_ip_route,
223 .saveroute = nf_ip_saveroute,
224 .reroute = nf_ip_reroute,
225 .route_key_size = sizeof(struct ip_rt_info),
226};
227
228static int ipv4_netfilter_init(void)
229{
230 return nf_register_afinfo(&nf_ip_afinfo);
231}
232
233static void ipv4_netfilter_fini(void)
234{
235 nf_unregister_afinfo(&nf_ip_afinfo);
236}
237
238module_init(ipv4_netfilter_init);
239module_exit(ipv4_netfilter_fini);