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natcap_server.c
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natcap_server.c
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/*
* Author: Chen Minqiang <[email protected]>
* Date : Sun, 05 Jun 2016 16:23:40 +0800
*
* This file is part of the natcap.
*
* natcap is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* natcap is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with natcap; see the file COPYING. If not, see
* <http://www.gnu.org/licenses/>.
*/
#include <linux/module.h>
#include <linux/version.h>
#include <linux/ip.h>
#include <linux/tcp.h>
#include <linux/udp.h>
#include <linux/if_ether.h>
#include <linux/netfilter.h>
#include <linux/inetdevice.h>
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_core.h>
#include <net/netfilter/nf_conntrack_zones.h>
#include "net/netfilter/nf_conntrack_seqadj.h"
#include <net/netfilter/nf_nat.h>
#include <net/ip.h>
#include <net/tcp.h>
#include "natcap.h"
#include "natcap_common.h"
#include "natcap_server.h"
#include "natcap_peer.h"
unsigned int server_flow_stop = 0;
unsigned int user_mark_natcap_mask = 0x00000000;
#define user_mark_natcap_set(mark, at) *(unsigned int *)(at) = ((*(unsigned int *)(at)) & (~user_mark_natcap_mask)) | ((mark) & user_mark_natcap_mask)
static inline int user_mark_natcap_get(unsigned int *at)
{
unsigned int idx;
unsigned int val;
unsigned int mask = user_mark_natcap_mask;
if (mask == 0)
return -1;
idx = ffs(mask) - 1;
val = ((*(unsigned int *)(at)) & mask);
return (val >> idx);
}
#define MAX_DNS_SERVER_NODE 32
static __be32 dns_server_node[MAX_DNS_SERVER_NODE];
static int dns_server_number = 0;
static void dns_server_node_random_select(__be32 *ip)
{
unsigned int idx = dns_server_number;
if (idx > 0) {
idx = (jiffies % idx) % MAX_DNS_SERVER_NODE;
idx = dns_server_node[idx];
if (idx != 0) {
*ip = idx;
}
}
}
/* called from user write */
int dns_server_node_add(__be32 ip)
{
if (dns_server_number < MAX_DNS_SERVER_NODE) {
dns_server_node[dns_server_number] = ip;
dns_server_number++;
return 0;
}
return -ENOMEM;
}
void dns_server_node_clean(void)
{
dns_server_number = 0;
memset(dns_server_node, 0, sizeof(__be32) * MAX_DNS_SERVER_NODE);
}
#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 10, 0)
static inline int natcap_auth(const struct nf_hook_state *state,
const struct net_device *in,
const struct net_device *out,
struct sk_buff *skb,
struct nf_conn *ct,
struct natcap_session *ns,
struct natcap_TCPOPT *tcpopt,
struct tuple *server)
#define NATCAP_AUTH(state, in, out, skb, ct, ns, tcpopt, server) natcap_auth(state, in, out, skb, ct, ns, tcpopt, server)
#else
static inline int natcap_auth(const struct net_device *in,
const struct net_device *out,
struct sk_buff *skb,
struct nf_conn *ct,
struct natcap_session *ns,
struct natcap_TCPOPT *tcpopt,
struct tuple *server)
#define NATCAP_AUTH(state, in, out, skb, ct, ns, tcpopt, server) natcap_auth(in, out, skb, ct, ns, tcpopt, server)
#endif
{
int ret;
struct iphdr *iph = ip_hdr(skb);
struct tcphdr *tcph = (struct tcphdr *)((void *)iph + iph->ihl * 4);
if (NATCAP_TCPOPT_TYPE(tcpopt->header.type) == NATCAP_TCPOPT_TYPE_ALL) {
if (server) {
server->ip = tcpopt->all.data.ip;
server->port = tcpopt->all.data.port;
server->encryption = tcpopt->header.encryption;
if (server->ip == PEER_XSYN_MASK_ADDR) {
server->ip = peer_xsyn_enumerate_addr();
} else if ((tcpopt->header.type & NATCAP_TCPOPT_TARGET)) {
server->ip = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u3.ip;
}
}
if ((auth_enabled & NATCAP_AUTH_MATCH_MAC)) {
struct sk_buff *uskb = uskb_of_this_cpu();
memcpy(eth_hdr(uskb)->h_source, tcpopt->all.data.mac_addr, ETH_ALEN);
ret = IP_SET_test_src_mac(state, in, out, uskb, "vclist");
if (ret > 0 && (auth_enabled & NATCAP_AUTH_MATCH_IP))
ret = IP_SET_test_src_ip(state, in, out, skb, "vciplist");
if (ret <= 0) {
ret = natcap_auth_request(tcpopt->all.data.mac_addr, iph->saddr);
}
if (ret <= 0) {
NATCAP_WARN("(%s)" DEBUG_FMT_TCP ": client=%02x:%02x:%02x:%02x:%02x:%02x u_hash=%u auth failed\n",
__FUNCTION__, DEBUG_ARG_TCP(iph,tcph),
tcpopt->all.data.mac_addr[0], tcpopt->all.data.mac_addr[1], tcpopt->all.data.mac_addr[2],
tcpopt->all.data.mac_addr[3], tcpopt->all.data.mac_addr[4], tcpopt->all.data.mac_addr[5],
ntohl(tcpopt->all.data.u_hash));
return E_NATCAP_AUTH_FAIL;
}
NATCAP_DEBUG("(%s)" DEBUG_FMT_TCP ": client=%02x:%02x:%02x:%02x:%02x:%02x u_hash=%u auth ok\n",
__FUNCTION__, DEBUG_ARG_TCP(iph,tcph),
tcpopt->all.data.mac_addr[0], tcpopt->all.data.mac_addr[1], tcpopt->all.data.mac_addr[2],
tcpopt->all.data.mac_addr[3], tcpopt->all.data.mac_addr[4], tcpopt->all.data.mac_addr[5],
ntohl(tcpopt->all.data.u_hash));
}
ns->n.u_hash = ntohl(tcpopt->all.data.u_hash);
} else if (NATCAP_TCPOPT_TYPE(tcpopt->header.type) == NATCAP_TCPOPT_TYPE_USER) {
if (server) {
return E_NATCAP_INVAL;
}
if ((auth_enabled & NATCAP_AUTH_MATCH_MAC)) {
struct sk_buff *uskb = uskb_of_this_cpu();
memcpy(eth_hdr(uskb)->h_source, tcpopt->user.data.mac_addr, ETH_ALEN);
ret = IP_SET_test_src_mac(state, in, out, uskb, "vclist");
if (ret > 0 && (auth_enabled & NATCAP_AUTH_MATCH_IP))
ret = IP_SET_test_src_ip(state, in, out, skb, "vciplist");
if (ret <= 0) {
ret = natcap_auth_request(tcpopt->user.data.mac_addr, iph->saddr);
}
if (ret <= 0) {
NATCAP_WARN("(%s)" DEBUG_FMT_TCP ": client=%02x:%02x:%02x:%02x:%02x:%02x u_hash=%u auth failed\n",
__FUNCTION__, DEBUG_ARG_TCP(iph,tcph),
tcpopt->user.data.mac_addr[0], tcpopt->user.data.mac_addr[1], tcpopt->user.data.mac_addr[2],
tcpopt->user.data.mac_addr[3], tcpopt->user.data.mac_addr[4], tcpopt->user.data.mac_addr[5],
ntohl(tcpopt->user.data.u_hash));
return E_NATCAP_AUTH_FAIL;
}
NATCAP_DEBUG("(%s)" DEBUG_FMT_TCP ": client=%02x:%02x:%02x:%02x:%02x:%02x u_hash=%u auth ok\n",
__FUNCTION__, DEBUG_ARG_TCP(iph,tcph),
tcpopt->user.data.mac_addr[0], tcpopt->user.data.mac_addr[1], tcpopt->user.data.mac_addr[2],
tcpopt->user.data.mac_addr[3], tcpopt->user.data.mac_addr[4], tcpopt->user.data.mac_addr[5],
ntohl(tcpopt->user.data.u_hash));
}
//clear NATCAP_TCPOPT_SPROXY if not ALL
tcpopt->header.type &= ~NATCAP_TCPOPT_SPROXY;
} else if (NATCAP_TCPOPT_TYPE(tcpopt->header.type) == NATCAP_TCPOPT_TYPE_DST) {
if (server) {
server->ip = tcpopt->dst.data.ip;
server->port = tcpopt->dst.data.port;
server->encryption = tcpopt->header.encryption;
if (server->ip == PEER_XSYN_MASK_ADDR) {
server->ip = peer_xsyn_enumerate_addr();
} else if ((tcpopt->header.type & NATCAP_TCPOPT_TARGET)) {
server->ip = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u3.ip;
}
//clear NATCAP_TCPOPT_SPROXY if not ALL
tcpopt->header.type &= ~NATCAP_TCPOPT_SPROXY;
} else if (!tcph->syn || tcph->ack) {
return E_NATCAP_INVAL;
}
} else if (server) {
return E_NATCAP_INVAL;
}
return E_NATCAP_OK;
}
static inline void natcap_udp_reply_cfm(const struct net_device *dev, struct sk_buff *oskb, struct nf_conn *ct) {
struct sk_buff *nskb;
struct ethhdr *neth, *oeth;
struct iphdr *niph, *oiph;
struct udphdr *oudph, *nudph;
struct natcap_session *ns;
int offset, add_len;
oeth = (struct ethhdr *)skb_mac_header(oskb);
oiph = ip_hdr(oskb);
oudph = (struct udphdr *)((void *)oiph + oiph->ihl * 4);
offset = sizeof(struct iphdr) + sizeof(struct udphdr) + 4 - (skb_headlen(oskb) + skb_tailroom(oskb));
add_len = offset < 0 ? 0 : offset;
offset += skb_tailroom(oskb);
nskb = skb_copy_expand(oskb, skb_headroom(oskb), skb_tailroom(oskb) + add_len, GFP_ATOMIC);
if (!nskb) {
NATCAP_ERROR(DEBUG_FMT_PREFIX "alloc_skb fail\n", DEBUG_ARG_PREFIX);
return;
}
nskb->tail += offset;
nskb->len = sizeof(struct iphdr) + sizeof(struct udphdr) + 4;
neth = eth_hdr(nskb);
niph = ip_hdr(nskb);
if ((char *)niph - (char *)neth >= ETH_HLEN) {
memcpy(neth->h_dest, oeth->h_source, ETH_ALEN);
memcpy(neth->h_source, oeth->h_dest, ETH_ALEN);
//neth->h_proto = htons(ETH_P_IP);
}
niph->saddr = oiph->daddr;
niph->daddr = oiph->saddr;
niph->version = oiph->version;
niph->ihl = sizeof(struct iphdr) / 4;
niph->tos = 0;
niph->tot_len = htons(nskb->len);
niph->ttl = 0x80;
niph->protocol = oiph->protocol;
niph->id = __constant_htons(0xdead);
niph->frag_off = 0x0;
nudph = (struct udphdr *)((void *)niph + niph->ihl * 4);
set_byte4((void *)nudph + sizeof(struct udphdr), __constant_htonl(NATCAP_E_MAGIC_A));
nudph->source = oudph->dest;
nudph->dest = oudph->source;
nudph->len = ntohs(nskb->len - niph->ihl * 4);
nudph->check = CSUM_MANGLED_0;
nskb->ip_summed = CHECKSUM_UNNECESSARY;
skb_rcsum_tcpudp(nskb);
ns = natcap_session_get(ct);
if ((NS_NATCAP_TCPUDPENC & ns->n.status)) {
natcap_udp_to_tcp_pack(nskb, ns, 1, NULL);
}
skb_push(nskb, (char *)niph - (char *)neth);
nskb->dev = (struct net_device *)dev;
skb_nfct_reset(nskb);
dev_queue_xmit(nskb);
}
static inline void natcap_auth_tcp_reply_rst(const struct net_device *dev, struct sk_buff *oskb, struct nf_conn *ct, int dir)
{
struct sk_buff *nskb;
struct ethhdr *neth, *oeth;
struct iphdr *niph, *oiph;
struct tcphdr *otcph, *ntcph;
struct natcap_session *ns;
int offset, add_len;
int header_len = 0;
u8 protocol = IPPROTO_TCP;
oeth = (struct ethhdr *)skb_mac_header(oskb);
oiph = ip_hdr(oskb);
otcph = (struct tcphdr *)((void *)oiph + oiph->ihl * 4);
ns = natcap_session_get(ct);
if ((NS_NATCAP_TCPUDPENC & ns->n.status)) {
header_len = 8;
protocol = IPPROTO_UDP;
}
offset = sizeof(struct iphdr) + sizeof(struct tcphdr) + header_len - (skb_headlen(oskb) + skb_tailroom(oskb));
add_len = offset < 0 ? 0 : offset;
offset += skb_tailroom(oskb);
nskb = skb_copy_expand(oskb, skb_headroom(oskb), skb_tailroom(oskb) + add_len, GFP_ATOMIC);
if (!nskb) {
NATCAP_ERROR(DEBUG_FMT_PREFIX "alloc_skb fail\n", DEBUG_ARG_PREFIX);
return;
}
nskb->tail += offset;
nskb->len = sizeof(struct iphdr) + sizeof(struct tcphdr);
neth = eth_hdr(nskb);
niph = ip_hdr(nskb);
if ((char *)niph - (char *)neth >= ETH_HLEN) {
memcpy(neth->h_dest, oeth->h_source, ETH_ALEN);
memcpy(neth->h_source, oeth->h_dest, ETH_ALEN);
//neth->h_proto = htons(ETH_P_IP);
}
memset(niph, 0, sizeof(struct iphdr));
niph->saddr = ct->tuplehash[dir].tuple.dst.u3.ip;
niph->daddr = ct->tuplehash[dir].tuple.src.u3.ip;
niph->version = oiph->version;
niph->ihl = sizeof(struct iphdr) / 4;
niph->tos = 0;
niph->tot_len = htons(nskb->len);
niph->ttl = 0x80;
niph->protocol = oiph->protocol;
niph->id = __constant_htons(0xdead);
niph->frag_off = 0x0;
ntcph = (struct tcphdr *)((char *)ip_hdr(nskb) + sizeof(struct iphdr));
ntcph->source = ct->tuplehash[dir].tuple.dst.u.tcp.port;
ntcph->dest = ct->tuplehash[dir].tuple.src.u.tcp.port;
ntcph->seq = otcph->ack_seq;
ntcph->ack_seq = htonl(ntohl(otcph->seq) + ntohs(oiph->tot_len) - oiph->ihl * 4 - otcph->doff * 4 + 1);
tcp_flag_word(ntcph) = TCP_FLAG_RST;
ntcph->res1 = 0;
ntcph->doff = 5;
ntcph->window = __constant_htons(0);
ntcph->check = 0;
ntcph->urg_ptr = 0;
nskb->ip_summed = CHECKSUM_UNNECESSARY;
skb_rcsum_tcpudp(nskb);
/*FIXME make TCP state happy */
skb_nfct_reset(nskb);
niph->saddr = ct->tuplehash[!dir].tuple.src.u3.ip;
niph->daddr = ct->tuplehash[!dir].tuple.dst.u3.ip;
ntcph->source = ct->tuplehash[!dir].tuple.src.u.tcp.port;
ntcph->dest = ct->tuplehash[!dir].tuple.dst.u.tcp.port;
/*XXX don't care what is returned */
nf_conntrack_in_compat(dev_net(dev), PF_INET, NF_INET_PRE_ROUTING, nskb);
niph->saddr = ct->tuplehash[dir].tuple.dst.u3.ip;
niph->daddr = ct->tuplehash[dir].tuple.src.u3.ip;
ntcph->source = ct->tuplehash[dir].tuple.dst.u.tcp.port;
ntcph->dest = ct->tuplehash[dir].tuple.src.u.tcp.port;
if (protocol == IPPROTO_UDP) {
int offlen;
offlen = skb_tail_pointer(nskb) - (unsigned char *)UDPH(ntcph) - 4;
BUG_ON(offlen < 0);
memmove((void *)UDPH(ntcph) + 4 + 8, (void *)UDPH(ntcph) + 4, offlen);
niph->tot_len = htons(ntohs(niph->tot_len) + 8);
UDPH(ntcph)->len = htons(ntohs(niph->tot_len) - niph->ihl * 4);
UDPH(ntcph)->check = CSUM_MANGLED_0;
nskb->len += 8;
set_byte4((void *)UDPH(ntcph) + 8, ns->peer.ver == 1 ? __constant_htonl(NATCAP_7_MAGIC) : __constant_htonl(NATCAP_F_MAGIC));
niph->protocol = IPPROTO_UDP;
skb_rcsum_tcpudp(nskb);
}
skb_push(nskb, (char *)niph - (char *)neth);
nskb->dev = (struct net_device *)dev;
skb_nfct_reset(nskb);
dev_queue_xmit(nskb);
}
static inline void natcap_auth_tcp_reply_rstack(const struct net_device *dev, struct sk_buff *oskb, struct nf_conn *ct)
{
struct sk_buff *nskb;
struct ethhdr *neth, *oeth;
struct iphdr *niph, *oiph;
struct tcphdr *otcph, *ntcph;
struct natcap_session *ns;
int offset, add_len;
int header_len = 0;
u8 protocol = IPPROTO_TCP;
oeth = (struct ethhdr *)skb_mac_header(oskb);
oiph = ip_hdr(oskb);
otcph = (struct tcphdr *)((void *)oiph + oiph->ihl * 4);
ns = natcap_session_get(ct);
if ((NS_NATCAP_TCPUDPENC & ns->n.status)) {
header_len = 8;
protocol = IPPROTO_UDP;
}
offset = sizeof(struct iphdr) + sizeof(struct tcphdr) + header_len - (skb_headlen(oskb) + skb_tailroom(oskb));
add_len = offset < 0 ? 0 : offset;
offset += skb_tailroom(oskb);
nskb = skb_copy_expand(oskb, skb_headroom(oskb), skb_tailroom(oskb) + add_len, GFP_ATOMIC);
if (!nskb) {
NATCAP_ERROR(DEBUG_FMT_PREFIX "alloc_skb fail\n", DEBUG_ARG_PREFIX);
return;
}
nskb->tail += offset;
nskb->len = sizeof(struct iphdr) + sizeof(struct tcphdr);
neth = eth_hdr(nskb);
niph = ip_hdr(nskb);
if ((char *)niph - (char *)neth >= ETH_HLEN) {
memcpy(neth->h_dest, oeth->h_source, ETH_ALEN);
memcpy(neth->h_source, oeth->h_dest, ETH_ALEN);
//neth->h_proto = htons(ETH_P_IP);
}
memset(niph, 0, sizeof(struct iphdr));
niph->saddr = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u3.ip;
niph->daddr = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip;
niph->version = oiph->version;
niph->ihl = sizeof(struct iphdr) / 4;
niph->tos = 0;
niph->tot_len = htons(nskb->len);
niph->ttl = 0x80;
niph->protocol = oiph->protocol;
niph->id = __constant_htons(0xdead);
niph->frag_off = 0x0;
ntcph = (struct tcphdr *)((char *)ip_hdr(nskb) + sizeof(struct iphdr));
ntcph->source = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u.tcp.port;
ntcph->dest = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.tcp.port;
ntcph->seq = otcph->ack_seq;
ntcph->ack_seq = htonl(ntohl(otcph->seq) + ntohs(oiph->tot_len) - oiph->ihl * 4 - otcph->doff * 4 + 1);
tcp_flag_word(ntcph) = TCP_FLAG_RST | TCP_FLAG_ACK;
ntcph->res1 = 0;
ntcph->doff = 5;
ntcph->window = __constant_htons(0);
ntcph->check = 0;
ntcph->urg_ptr = 0;
nskb->ip_summed = CHECKSUM_UNNECESSARY;
skb_rcsum_tcpudp(nskb);
/*FIXME make TCP state happy */
skb_nfct_reset(nskb);
niph->saddr = ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip;
niph->daddr = ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip;
ntcph->source = ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u.tcp.port;
ntcph->dest = ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u.tcp.port;
/*XXX don't care what is returned */
nf_conntrack_in_compat(dev_net(dev), PF_INET, NF_INET_PRE_ROUTING, nskb);
niph->saddr = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u3.ip;
niph->daddr = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip;
ntcph->source = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u.tcp.port;
ntcph->dest = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.tcp.port;
if (protocol == IPPROTO_UDP) {
int offlen;
offlen = skb_tail_pointer(nskb) - (unsigned char *)UDPH(ntcph) - 4;
BUG_ON(offlen < 0);
memmove((void *)UDPH(ntcph) + 4 + 8, (void *)UDPH(ntcph) + 4, offlen);
niph->tot_len = htons(ntohs(niph->tot_len) + 8);
UDPH(ntcph)->len = htons(ntohs(niph->tot_len) - niph->ihl * 4);
UDPH(ntcph)->check = CSUM_MANGLED_0;
nskb->len += 8;
set_byte4((void *)UDPH(ntcph) + 8, ns->peer.ver == 1 ? __constant_htonl(NATCAP_7_MAGIC) : __constant_htonl(NATCAP_F_MAGIC));
niph->protocol = IPPROTO_UDP;
skb_rcsum_tcpudp(nskb);
}
skb_push(nskb, (char *)niph - (char *)neth);
nskb->dev = (struct net_device *)dev;
skb_nfct_reset(nskb);
dev_queue_xmit(nskb);
}
static inline void natcap_auth_reply_payload(const char *payload, int payload_len, struct sk_buff *oskb, const struct net_device *dev, struct nf_conn *ct)
{
struct sk_buff *nskb;
struct ethhdr *neth, *oeth;
struct iphdr *niph, *oiph;
struct tcphdr *otcph, *ntcph;
struct natcap_session *ns;
int offset, add_len;
int header_len = 0;
u8 protocol = IPPROTO_TCP;
char *data;
oeth = (struct ethhdr *)skb_mac_header(oskb);
oiph = ip_hdr(oskb);
otcph = (struct tcphdr *)((void *)oiph + oiph->ihl * 4);
ns = natcap_session_get(ct);
if ((NS_NATCAP_TCPUDPENC & ns->n.status)) {
header_len = 8;
protocol = IPPROTO_UDP;
}
offset = sizeof(struct iphdr) + sizeof(struct tcphdr) + payload_len + header_len - (skb_headlen(oskb) + skb_tailroom(oskb));
add_len = offset < 0 ? 0 : offset;
offset += skb_tailroom(oskb);
nskb = skb_copy_expand(oskb, skb_headroom(oskb), skb_tailroom(oskb) + add_len, GFP_ATOMIC);
if (!nskb) {
NATCAP_ERROR(DEBUG_FMT_PREFIX "alloc_skb fail\n", DEBUG_ARG_PREFIX);
return;
}
nskb->tail += offset;
nskb->len = sizeof(struct iphdr) + sizeof(struct tcphdr) + payload_len;
neth = eth_hdr(nskb);
niph = ip_hdr(nskb);
if ((char *)niph - (char *)neth >= ETH_HLEN) {
memcpy(neth->h_dest, oeth->h_source, ETH_ALEN);
memcpy(neth->h_source, oeth->h_dest, ETH_ALEN);
//neth->h_proto = htons(ETH_P_IP);
}
memset(niph, 0, sizeof(struct iphdr));
niph->saddr = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u3.ip;
niph->daddr = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip;
niph->version = oiph->version;
niph->ihl = sizeof(struct iphdr) / 4;
niph->tos = 0;
niph->tot_len = htons(nskb->len);
niph->ttl = 0x80;
niph->protocol = oiph->protocol;
niph->id = __constant_htons(0xdead);
niph->frag_off = 0x0;
ntcph = (struct tcphdr *)((char *)ip_hdr(nskb) + sizeof(struct iphdr));
ntcph->source = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u.tcp.port;
ntcph->dest = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.tcp.port;
data = (char *)ntcph + sizeof(struct tcphdr);
memcpy(data, payload, payload_len);
ntcph->seq = otcph->ack_seq;
ntcph->ack_seq = htonl(ntohl(otcph->seq) + ntohs(oiph->tot_len) - oiph->ihl * 4 - otcph->doff * 4);
tcp_flag_word(ntcph) = TCP_FLAG_PSH | TCP_FLAG_ACK | TCP_FLAG_FIN;
ntcph->res1 = 0;
ntcph->doff = 5;
ntcph->window = __constant_htons(65535);
ntcph->check = 0;
ntcph->urg_ptr = 0;
if ((NS_NATCAP_ENC & ns->n.status)) {
natcap_data_encode(data, payload_len);
}
nskb->ip_summed = CHECKSUM_UNNECESSARY;
skb_rcsum_tcpudp(nskb);
/*FIXME make TCP state happy */
skb_nfct_reset(nskb);
niph->saddr = ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip;
niph->daddr = ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip;
ntcph->source = ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u.tcp.port;
ntcph->dest = ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u.tcp.port;
/*XXX don't care what is returned */
nf_conntrack_in_compat(dev_net(dev), PF_INET, NF_INET_PRE_ROUTING, nskb);
niph->saddr = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u3.ip;
niph->daddr = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip;
ntcph->source = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u.tcp.port;
ntcph->dest = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.tcp.port;
if (protocol == IPPROTO_UDP) {
int offlen;
offlen = skb_tail_pointer(nskb) - (unsigned char *)UDPH(ntcph) - 4;
BUG_ON(offlen < 0);
memmove((void *)UDPH(ntcph) + 4 + 8, (void *)UDPH(ntcph) + 4, offlen);
niph->tot_len = htons(ntohs(niph->tot_len) + 8);
UDPH(ntcph)->len = htons(ntohs(niph->tot_len) - niph->ihl * 4);
UDPH(ntcph)->check = CSUM_MANGLED_0;
nskb->len += 8;
set_byte4((void *)UDPH(ntcph) + 8, ns->peer.ver == 1 ? __constant_htonl(NATCAP_7_MAGIC) : __constant_htonl(NATCAP_F_MAGIC));
niph->protocol = IPPROTO_UDP;
skb_rcsum_tcpudp(nskb);
}
skb_push(nskb, (char *)niph - (char *)neth);
nskb->dev = (struct net_device *)dev;
skb_nfct_reset(nskb);
dev_queue_xmit(nskb);
}
char *auth_http_redirect_url = NULL;
static inline void natcap_auth_http_302(const struct net_device *dev, struct sk_buff *skb, struct nf_conn *ct)
{
const char *http_header_fmt = ""
"HTTP/1.1 302 Moved Temporarily\r\n"
"Connection: close\r\n"
"Cache-Control: no-cache\r\n"
"Content-Type: text/html; charset=UTF-8\r\n"
"Location: %s\r\n"
"Content-Length: %u\r\n"
"\r\n";
const char *http_data_fmt = ""
"<HTML><HEAD><meta http-equiv=\"content-type\" content=\"text/html;charset=utf-8\">\r\n"
"<TITLE>302 Moved</TITLE></HEAD><BODY>\r\n"
"<H1>302 Moved</H1>\r\n"
"The document has moved\r\n"
"<A HREF=\"%s\">here</A>.\r\n"
"</BODY></HTML>\r\n";
int n = 0;
struct {
char location[128];
char data[384];
char header[384];
char payload[0];
} *http = kmalloc(2048, GFP_ATOMIC);
if (!http)
return;
if (auth_http_redirect_url) {
snprintf(http->location, sizeof(http->location), "%s", auth_http_redirect_url);
} else {
snprintf(http->location, sizeof(http->location), "http://router-sh.ptpt52.com/index.html?_t=%lu", jiffies);
}
http->location[sizeof(http->location) - 1] = 0;
snprintf(http->data, sizeof(http->data), http_data_fmt, http->location);
http->data[sizeof(http->data) - 1] = 0;
snprintf(http->header, sizeof(http->header), http_header_fmt, http->location, n);
http->header[sizeof(http->header) - 1] = 0;
n = sprintf(http->payload, "%s%s", http->header, http->data);
natcap_auth_reply_payload(http->payload, n, skb, dev, ct);
kfree(http);
}
static inline int natcap_auth_tcp_to_rst(struct sk_buff *skb)
{
int offset = 0;
struct iphdr *iph;
struct tcphdr *tcph;
iph = ip_hdr(skb);
if (iph->protocol != IPPROTO_TCP) {
return -1;
}
if (skb->len < ntohs(iph->tot_len)) {
return -1;
}
tcph = (struct tcphdr *)((void *)iph + iph->ihl * 4);
offset = iph->ihl * 4 + sizeof(struct tcphdr) - skb->len;
if (offset > 0) {
return -1;
}
if (pskb_trim(skb, skb->len + offset)) {
return -1;
}
tcp_flag_word(tcph) = TCP_FLAG_RST;
tcph->res1 = 0;
tcph->doff = 5;
tcph->window = __constant_htons(0);
tcph->check = 0;
tcph->urg_ptr = 0;
iph->tot_len = htons(skb->len);
iph->id = __constant_htons(0xdead);
iph->frag_off = 0;
skb_rcsum_tcpudp(skb);
return 0;
}
static inline unsigned int natcap_try_http_redirect(struct iphdr *iph, struct sk_buff *skb, struct nf_conn *ct, const struct net_device *in)
{
void *l4;
unsigned char *data;
int data_len;
struct natcap_session *ns = natcap_session_get(ct);
if (!in) {
return NF_ACCEPT;
}
if (!skb_make_writable(skb, iph->ihl * 4 + sizeof(struct tcphdr))) {
return NF_DROP;
}
iph = ip_hdr(skb);
l4 = (void *)iph + iph->ihl * 4;
if (!skb_make_writable(skb, iph->ihl * 4 + TCPH(l4)->doff * 4)) {
return NF_DROP;
}
iph = ip_hdr(skb);
l4 = (void *)iph + iph->ihl * 4;
data = skb->data + iph->ihl * 4 + TCPH(l4)->doff * 4;
data_len = ntohs(iph->tot_len) - (iph->ihl * 4 + TCPH(l4)->doff * 4);
if ((data_len > 4 && strncasecmp(data, "GET ", 4) == 0) ||
(data_len > 5 && strncasecmp(data, "POST ", 5) == 0)) {
short_set_bit(NS_NATCAP_DROP_BIT, &ns->n.status);
natcap_auth_http_302(in, skb, ct);
natcap_auth_tcp_to_rst(skb);
return NF_ACCEPT;
} else if (data_len > 0) {
short_set_bit(NS_NATCAP_DROP_BIT, &ns->n.status);
natcap_auth_tcp_reply_rst(in, skb, ct, IP_CT_DIR_ORIGINAL);
natcap_auth_tcp_to_rst(skb);
return NF_ACCEPT;
}
return NF_ACCEPT;
}
static inline void natcap_confusion_tcp_reply_ack(const struct net_device *dev, struct sk_buff *oskb, struct nf_conn *ct, struct natcap_session *ns)
{
struct sk_buff *nskb;
struct ethhdr *neth, *oeth;
struct iphdr *niph, *oiph;
struct tcphdr *otcph, *ntcph;
int offset, add_len;
u8 protocol = IPPROTO_TCP;
struct natcap_TCPOPT *tcpopt;
int size = ALIGN(sizeof(struct natcap_TCPOPT_header), sizeof(unsigned int));
oeth = (struct ethhdr *)skb_mac_header(oskb);
oiph = ip_hdr(oskb);
otcph = (struct tcphdr *)((void *)oiph + oiph->ihl * 4);
offset = sizeof(struct iphdr) + sizeof(struct tcphdr) + size + ns->n.tcp_ack_offset - (skb_headlen(oskb) + skb_tailroom(oskb));
add_len = offset < 0 ? 0 : offset;
offset += skb_tailroom(oskb);
nskb = skb_copy_expand(oskb, skb_headroom(oskb), skb_tailroom(oskb) + add_len, GFP_ATOMIC);
if (!nskb) {
NATCAP_ERROR(DEBUG_FMT_PREFIX "alloc_skb fail\n", DEBUG_ARG_PREFIX);
return;
}
nskb->tail += offset;
nskb->len = sizeof(struct iphdr) + sizeof(struct tcphdr) + size + ns->n.tcp_ack_offset;
neth = eth_hdr(nskb);
niph = ip_hdr(nskb);
if ((char *)niph - (char *)neth >= ETH_HLEN) {
memcpy(neth->h_dest, oeth->h_source, ETH_ALEN);
memcpy(neth->h_source, oeth->h_dest, ETH_ALEN);
//neth->h_proto = htons(ETH_P_IP);
}
memset(niph, 0, sizeof(struct iphdr));
niph->saddr = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u3.ip;
niph->daddr = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip;
niph->version = oiph->version;
niph->ihl = sizeof(struct iphdr) / 4;
niph->tos = 0;
niph->tot_len = htons(nskb->len);
niph->ttl = 0x80;
niph->protocol = protocol;
niph->id = __constant_htons(0xdead);
niph->frag_off = 0x0;
ntcph = (struct tcphdr *)((char *)ip_hdr(nskb) + sizeof(struct iphdr));
ntcph->source = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u.tcp.port;
ntcph->dest = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.tcp.port;
ntcph->seq = otcph->ack_seq;
ntcph->ack_seq = htonl(ntohl(otcph->seq) + ntohs(oiph->tot_len) - oiph->ihl * 4 - otcph->doff * 4);
tcp_flag_word(ntcph) = TCP_FLAG_ACK;
ntcph->res1 = 0;
ntcph->doff = (sizeof(struct tcphdr) + size) / 4;
ntcph->window = __constant_htons(65535);
ntcph->check = 0;
ntcph->urg_ptr = 0;
tcpopt = (struct natcap_TCPOPT *)((char *)ntcph + sizeof(struct tcphdr));
tcpopt->header.type = NATCAP_TCPOPT_TYPE_CONFUSION;
tcpopt->header.opcode = TCPOPT_NATCAP;
tcpopt->header.opsize = size;
tcpopt->header.encryption = 0;
memcpy((void *)tcpopt + size, htp_confusion_rsp, ns->n.tcp_ack_offset);
nskb->ip_summed = CHECKSUM_UNNECESSARY;
skb_rcsum_tcpudp(nskb);
skb_push(nskb, (char *)niph - (char *)neth);
nskb->dev = (struct net_device *)dev;
skb_nfct_reset(nskb);
dev_queue_xmit(nskb);
}
#if LINUX_VERSION_CODE < KERNEL_VERSION(3, 13, 0)
static unsigned int natcap_server_forward_hook(unsigned int hooknum,
struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
#elif LINUX_VERSION_CODE < KERNEL_VERSION(4, 1, 0)
static unsigned int natcap_server_forward_hook(const struct nf_hook_ops *ops,
struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
#elif LINUX_VERSION_CODE < KERNEL_VERSION(4, 4, 0)
static unsigned int natcap_server_forward_hook(const struct nf_hook_ops *ops,
struct sk_buff *skb,
const struct nf_hook_state *state)
{
const struct net_device *in = state->in;
#else
static unsigned int natcap_server_forward_hook(void *priv,
struct sk_buff *skb,
const struct nf_hook_state *state)
{
const struct net_device *in = state->in;
#endif
enum ip_conntrack_info ctinfo;
struct nf_conn *ct;
struct natcap_session *ns;
struct iphdr *iph;
if (disabled)
return NF_ACCEPT;
iph = ip_hdr(skb);
if (iph->protocol != IPPROTO_TCP && iph->protocol != IPPROTO_UDP) {
return NF_ACCEPT;
}
ct = nf_ct_get(skb, &ctinfo);
if (NULL == ct) {
return NF_ACCEPT;
}
if (!(IPS_NATCAP_SERVER & ct->status)) {
return NF_ACCEPT;
}
if ((IPS_NATCAP_BYPASS & ct->status)) {
return NF_ACCEPT;
}
ns = natcap_session_get(ct);
if (ns && (NS_NATCAP_DROP & ns->n.status)) {
if (iph->protocol == IPPROTO_TCP) {
void *l4 = (void *)iph + iph->ihl * 4;
if (CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) {
if (TCPH(l4)->fin && TCPH(l4)->ack) {
natcap_auth_tcp_reply_rstack(in, skb, ct);
}
} else {
if (!(TCPH(l4)->syn && TCPH(l4)->ack)) {
natcap_auth_tcp_reply_rst(in, skb, ct, IP_CT_DIR_REPLY);
natcap_auth_tcp_to_rst(skb);
return NF_ACCEPT;
}
}
}
//not drop here
return NF_ACCEPT;
}
if (iph->protocol == IPPROTO_TCP) {
if (ns && (NS_NATCAP_AUTH & ns->n.status)) {
if (CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) {
return natcap_try_http_redirect(iph, skb, ct, in);
}
}
}
return NF_ACCEPT;
}
#if LINUX_VERSION_CODE < KERNEL_VERSION(3, 13, 0)
static unsigned int natcap_server_pre_ct_test_hook(unsigned int hooknum,
struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
#elif LINUX_VERSION_CODE < KERNEL_VERSION(4, 1, 0)
static unsigned int natcap_server_pre_ct_test_hook(const struct nf_hook_ops *ops,
struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
//unsigned int hooknum = ops->hooknum;
#elif LINUX_VERSION_CODE < KERNEL_VERSION(4, 4, 0)
static unsigned int natcap_server_pre_ct_test_hook(const struct nf_hook_ops *ops,
struct sk_buff *skb,
const struct nf_hook_state *state)
{
//unsigned int hooknum = state->hook;
const struct net_device *in = state->in;
//const struct net_device *out = state->out;
#else
static unsigned int natcap_server_pre_ct_test_hook(void *priv,
struct sk_buff *skb,
const struct nf_hook_state *state)
{
//unsigned int hooknum = state->hook;
const struct net_device *in = state->in;
//const struct net_device *out = state->out;
#endif
enum ip_conntrack_info ctinfo;
struct nf_conn *ct;
struct iphdr *iph;
void *l4;
if (disabled)
return NF_ACCEPT;
iph = ip_hdr(skb);
if (iph->protocol != IPPROTO_TCP && iph->protocol != IPPROTO_UDP) {
return NF_ACCEPT;
}
ct = nf_ct_get(skb, &ctinfo);
if (NULL == ct) {
return NF_ACCEPT;
}
if (CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL) {
return NF_ACCEPT;
}
if (nf_ct_is_confirmed(ct)) {
return NF_ACCEPT;
}
if ((IPS_NATCAP & ct->status)) {
return NF_ACCEPT;
}
if ((IPS_NATCAP_BYPASS & ct->status)) {
return NF_ACCEPT;
}
if (iph->protocol == IPPROTO_TCP) {
if (!skb_make_writable(skb, iph->ihl * 4 + sizeof(struct tcphdr))) {
return NF_DROP;
}
iph = ip_hdr(skb);
l4 = (void *)iph + iph->ihl * 4;
if (!skb_make_writable(skb, iph->ihl * 4 + TCPH(l4)->doff * 4)) {
return NF_DROP;
}
iph = ip_hdr(skb);
l4 = (void *)iph + iph->ihl * 4;
if (!TCPH(l4)->syn || TCPH(l4)->ack) {
return NF_ACCEPT;
}
if (natcap_tcp_decode_header(TCPH(l4)) == NULL) {
return NF_ACCEPT;
}
set_bit(IPS_NATCAP_SERVER_BIT, &ct->status);
if (!inet_is_local(in, iph->daddr)) {
set_bit(IPS_NATCAP_BYPASS_BIT, &ct->status);
}
return NF_ACCEPT;
} else if (iph->protocol == IPPROTO_UDP) {
if (!skb_make_writable(skb, iph->ihl * 4 + sizeof(struct udphdr))) {
return NF_DROP;
}
iph = ip_hdr(skb);
l4 = (void *)iph + iph->ihl * 4;
if (skb_make_writable(skb, iph->ihl * 4 + sizeof(struct udphdr) + 12)) {
iph = ip_hdr(skb);
l4 = (void *)iph + iph->ihl * 4;
if (get_byte4((void *)UDPH(l4) + sizeof(struct udphdr)) == __constant_htonl(NATCAP_E_MAGIC) ||
(get_byte4((void *)UDPH(l4) + sizeof(struct udphdr)) == __constant_htonl(NATCAP_D_MAGIC) &&
skb_make_writable(skb, iph->ihl * 4 + sizeof(struct udphdr) + 24))) {
iph = ip_hdr(skb);
l4 = (void *)iph + iph->ihl * 4;
set_bit(IPS_NATCAP_SERVER_BIT, &ct->status);
if (!inet_is_local(in, iph->daddr)) {
set_bit(IPS_NATCAP_BYPASS_BIT, &ct->status);
}
return NF_ACCEPT;
}
}
iph = ip_hdr(skb);
l4 = (void *)iph + iph->ihl * 4;
}
return NF_ACCEPT;
}
#if LINUX_VERSION_CODE < KERNEL_VERSION(3, 13, 0)
static unsigned int natcap_server_pre_ct_in_hook(unsigned int hooknum,
struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
#elif LINUX_VERSION_CODE < KERNEL_VERSION(4, 1, 0)
static unsigned int natcap_server_pre_ct_in_hook(const struct nf_hook_ops *ops,
struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
unsigned int hooknum = ops->hooknum;
#elif LINUX_VERSION_CODE < KERNEL_VERSION(4, 4, 0)
static unsigned int natcap_server_pre_ct_in_hook(const struct nf_hook_ops *ops,
struct sk_buff *skb,
const struct nf_hook_state *state)
{
unsigned int hooknum = state->hook;
const struct net_device *in = state->in;
const struct net_device *out = state->out;
#else
static unsigned int natcap_server_pre_ct_in_hook(void *priv,
struct sk_buff *skb,
const struct nf_hook_state *state)