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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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 | /* IPv4 specific functions of netfilter core */
#include <linux/kernel.h>
#include <linux/netfilter.h>
#include <linux/netfilter_ipv4.h>
#include <linux/ip.h>
#include <linux/skbuff.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 *skb, unsigned addr_type)
{
const struct iphdr *iph = ip_hdr(skb);
struct rtable *rt;
struct flowi fl = {};
struct dst_entry *odst;
unsigned int hh_len;
unsigned int type;
type = inet_addr_type(iph->saddr);
if (addr_type == RTN_UNSPEC)
addr_type = type;
/* 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 (addr_type == RTN_LOCAL) {
fl.nl_u.ip4_u.daddr = iph->daddr;
if (type == RTN_LOCAL)
fl.nl_u.ip4_u.saddr = iph->saddr;
fl.nl_u.ip4_u.tos = RT_TOS(iph->tos);
fl.oif = skb->sk ? skb->sk->sk_bound_dev_if : 0;
fl.mark = skb->mark;
if (ip_route_output_key(&rt, &fl) != 0)
return -1;
/* Drop old route. */
dst_release(skb->dst);
skb->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 = skb->dst;
if (ip_route_input(skb, 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 (skb->dst->error)
return -1;
#ifdef CONFIG_XFRM
if (!(IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) &&
xfrm_decode_session(skb, &fl, AF_INET) == 0)
if (xfrm_lookup(&skb->dst, &fl, skb->sk, 0))
return -1;
#endif
/* Change in oif may mean change in hh_len. */
hh_len = skb->dst->dev->hard_header_len;
if (skb_headroom(skb) < hh_len &&
pskb_expand_head(skb, hh_len - skb_headroom(skb), 0, GFP_ATOMIC))
return -1;
return 0;
}
EXPORT_SYMBOL(ip_route_me_harder);
#ifdef CONFIG_XFRM
int ip_xfrm_me_harder(struct sk_buff *skb)
{
struct flowi fl;
unsigned int hh_len;
struct dst_entry *dst;
if (IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED)
return 0;
if (xfrm_decode_session(skb, &fl, AF_INET) < 0)
return -1;
dst = skb->dst;
if (dst->xfrm)
dst = ((struct xfrm_dst *)dst)->route;
dst_hold(dst);
if (xfrm_lookup(&dst, &fl, skb->sk, 0) < 0)
return -1;
dst_release(skb->dst);
skb->dst = dst;
/* Change in oif may mean change in hh_len. */
hh_len = skb->dst->dev->hard_header_len;
if (skb_headroom(skb) < hh_len &&
pskb_expand_head(skb, hh_len - skb_headroom(skb), 0, GFP_ATOMIC))
return -1;
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 {
__be32 daddr;
__be32 saddr;
u_int8_t tos;
};
static void nf_ip_saveroute(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 = ip_hdr(skb);
rt_info->tos = iph->tos;
rt_info->daddr = iph->daddr;
rt_info->saddr = iph->saddr;
}
}
static int nf_ip_reroute(struct sk_buff *skb, const struct nf_info *info)
{
const struct ip_rt_info *rt_info = nf_info_reroute(info);
if (info->hook == NF_IP_LOCAL_OUT) {
const struct iphdr *iph = ip_hdr(skb);
if (!(iph->tos == rt_info->tos
&& iph->daddr == rt_info->daddr
&& iph->saddr == rt_info->saddr))
return ip_route_me_harder(skb, RTN_UNSPEC);
}
return 0;
}
__sum16 nf_ip_checksum(struct sk_buff *skb, unsigned int hook,
unsigned int dataoff, u_int8_t protocol)
{
const struct iphdr *iph = ip_hdr(skb);
__sum16 csum = 0;
switch (skb->ip_summed) {
case CHECKSUM_COMPLETE:
if (hook != NF_IP_PRE_ROUTING && hook != NF_IP_LOCAL_IN)
break;
if ((protocol == 0 && !csum_fold(skb->csum)) ||
!csum_tcpudp_magic(iph->saddr, iph->daddr,
skb->len - dataoff, protocol,
skb->csum)) {
skb->ip_summed = CHECKSUM_UNNECESSARY;
break;
}
/* fall through */
case CHECKSUM_NONE:
if (protocol == 0)
skb->csum = 0;
else
skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr,
skb->len - dataoff,
protocol, 0);
csum = __skb_checksum_complete(skb);
}
return csum;
}
EXPORT_SYMBOL(nf_ip_checksum);
static struct nf_afinfo nf_ip_afinfo = {
.family = AF_INET,
.checksum = nf_ip_checksum,
.saveroute = nf_ip_saveroute,
.reroute = nf_ip_reroute,
.route_key_size = sizeof(struct ip_rt_info),
};
static int ipv4_netfilter_init(void)
{
return nf_register_afinfo(&nf_ip_afinfo);
}
static void ipv4_netfilter_fini(void)
{
nf_unregister_afinfo(&nf_ip_afinfo);
}
module_init(ipv4_netfilter_init);
module_exit(ipv4_netfilter_fini);
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