1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
|
/* IPv4 specific functions of netfilter core */
#include <linux/kernel.h>
#include <linux/netfilter.h>
#include <linux/netfilter_ipv4.h>
#include <linux/ip.h>
#include <net/route.h>
#include <net/xfrm.h>
#include <net/ip.h>
/* route_me_harder function, used by iptable_nat, iptable_mangle + ip_queue */
int ip_route_me_harder(struct sk_buff **pskb)
{
struct iphdr *iph = (*pskb)->nh.iph;
struct rtable *rt;
struct flowi fl = {};
struct dst_entry *odst;
unsigned int hh_len;
/* some non-standard hacks like ipt_REJECT.c:send_reset() can cause
* packets with foreign saddr to appear on the NF_IP_LOCAL_OUT hook.
*/
if (inet_addr_type(iph->saddr) == RTN_LOCAL) {
fl.nl_u.ip4_u.daddr = iph->daddr;
fl.nl_u.ip4_u.saddr = iph->saddr;
fl.nl_u.ip4_u.tos = RT_TOS(iph->tos);
fl.oif = (*pskb)->sk ? (*pskb)->sk->sk_bound_dev_if : 0;
#ifdef CONFIG_IP_ROUTE_FWMARK
fl.nl_u.ip4_u.fwmark = (*pskb)->nfmark;
#endif
if (ip_route_output_key(&rt, &fl) != 0)
return -1;
/* Drop old route. */
dst_release((*pskb)->dst);
(*pskb)->dst = &rt->u.dst;
} else {
/* non-local src, find valid iif to satisfy
* rp-filter when calling ip_route_input. */
fl.nl_u.ip4_u.daddr = iph->saddr;
if (ip_route_output_key(&rt, &fl) != 0)
return -1;
odst = (*pskb)->dst;
if (ip_route_input(*pskb, iph->daddr, iph->saddr,
RT_TOS(iph->tos), rt->u.dst.dev) != 0) {
dst_release(&rt->u.dst);
return -1;
}
dst_release(&rt->u.dst);
dst_release(odst);
}
if ((*pskb)->dst->error)
return -1;
#ifdef CONFIG_XFRM
if (!(IPCB(*pskb)->flags & IPSKB_XFRM_TRANSFORMED) &&
xfrm_decode_session(*pskb, &fl, AF_INET) == 0)
if (xfrm_lookup(&(*pskb)->dst, &fl, (*pskb)->sk, 0))
return -1;
#endif
/* Change in oif may mean change in hh_len. */
hh_len = (*pskb)->dst->dev->hard_header_len;
if (skb_headroom(*pskb) < hh_len) {
struct sk_buff *nskb;
nskb = skb_realloc_headroom(*pskb, hh_len);
if (!nskb)
return -1;
if ((*pskb)->sk)
skb_set_owner_w(nskb, (*pskb)->sk);
kfree_skb(*pskb);
*pskb = nskb;
}
return 0;
}
EXPORT_SYMBOL(ip_route_me_harder);
#ifdef CONFIG_XFRM
int ip_xfrm_me_harder(struct sk_buff **pskb)
{
struct flowi fl;
unsigned int hh_len;
struct dst_entry *dst;
if (IPCB(*pskb)->flags & IPSKB_XFRM_TRANSFORMED)
return 0;
if (xfrm_decode_session(*pskb, &fl, AF_INET) < 0)
return -1;
dst = (*pskb)->dst;
if (dst->xfrm)
dst = ((struct xfrm_dst *)dst)->route;
dst_hold(dst);
if (xfrm_lookup(&dst, &fl, (*pskb)->sk, 0) < 0)
return -1;
dst_release((*pskb)->dst);
(*pskb)->dst = dst;
/* Change in oif may mean change in hh_len. */
hh_len = (*pskb)->dst->dev->hard_header_len;
if (skb_headroom(*pskb) < hh_len) {
struct sk_buff *nskb;
nskb = skb_realloc_headroom(*pskb, hh_len);
if (!nskb)
return -1;
if ((*pskb)->sk)
skb_set_owner_w(nskb, (*pskb)->sk);
kfree_skb(*pskb);
*pskb = nskb;
}
return 0;
}
EXPORT_SYMBOL(ip_xfrm_me_harder);
#endif
void (*ip_nat_decode_session)(struct sk_buff *, struct flowi *);
EXPORT_SYMBOL(ip_nat_decode_session);
/*
* Extra routing may needed on local out, as the QUEUE target never
* returns control to the table.
*/
struct ip_rt_info {
u_int32_t daddr;
u_int32_t saddr;
u_int8_t tos;
};
static void queue_save(const struct sk_buff *skb, struct nf_info *info)
{
struct ip_rt_info *rt_info = nf_info_reroute(info);
if (info->hook == NF_IP_LOCAL_OUT) {
const struct iphdr *iph = skb->nh.iph;
rt_info->tos = iph->tos;
rt_info->daddr = iph->daddr;
rt_info->saddr = iph->saddr;
}
}
static int queue_reroute(struct sk_buff **pskb, const struct nf_info *info)
{
const struct ip_rt_info *rt_info = nf_info_reroute(info);
if (info->hook == NF_IP_LOCAL_OUT) {
struct iphdr *iph = (*pskb)->nh.iph;
if (!(iph->tos == rt_info->tos
&& iph->daddr == rt_info->daddr
&& iph->saddr == rt_info->saddr))
return ip_route_me_harder(pskb);
}
return 0;
}
static struct nf_queue_rerouter ip_reroute = {
.rer_size = sizeof(struct ip_rt_info),
.save = queue_save,
.reroute = queue_reroute,
};
static int init(void)
{
return nf_register_queue_rerouter(PF_INET, &ip_reroute);
}
static void fini(void)
{
nf_unregister_queue_rerouter(PF_INET);
}
module_init(init);
module_exit(fini);
|
