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xt_NAT.c
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#include <linux/module.h>
#include <linux/timer.h>
#include <linux/skbuff.h>
#include <linux/spinlock.h>
#include <linux/jhash.h>
#include <linux/vmalloc.h>
#include <linux/ip.h>
#include <linux/tcp.h>
#include <linux/udp.h>
#include <linux/icmp.h>
#include <linux/version.h>
#include <linux/netfilter/x_tables.h>
#include <linux/inet.h>
#include <linux/proc_fs.h>
#include <net/tcp.h>
#include "compat.h"
#include "xt_NAT.h"
#define FLAG_REPLIED (1 << 0) /* 000001 */
#define FLAG_TCP_FIN (1 << 1) /* 000010 */
#define TCP_SYN_ACK 0x12
#define TCP_FIN_RST 0x05
static LIST_HEAD(usock_list);
static int sndbuf = 1310720;
static int flowsetID = 300;
static unsigned int pdu_data_records = 0;
static unsigned int pdu_seq = 0;
struct netflow9_pdu pdu;
struct netflow9_template templateV9;
static DEFINE_SPINLOCK(nfsend_lock);
static atomic64_t sessions_active = ATOMIC_INIT(0);
static atomic64_t users_active = ATOMIC_INIT(0);
static atomic64_t sessions_tried = ATOMIC_INIT(0);
static atomic64_t sessions_created = ATOMIC_INIT(0);
static atomic64_t dnat_dropped = ATOMIC_INIT(0);
static atomic64_t frags = ATOMIC_INIT(0);
static atomic64_t related_icmp = ATOMIC_INIT(0);
static char nat_pool_buf[128] = "127.0.0.1-127.0.0.1";
static char *nat_pool = nat_pool_buf;
module_param(nat_pool, charp, 0444);
MODULE_PARM_DESC(nat_pool, "NAT pool range (addr_start-addr_end), default = 127.0.0.1-127.0.0.1");
static int nat_hash_size = 256 * 1024;
module_param(nat_hash_size, int, 0444);
MODULE_PARM_DESC(nat_hash_size, "nat hash size, default = 256k");
static int users_hash_size = 64 * 1024;
module_param(users_hash_size, int, 0444);
MODULE_PARM_DESC(users_hash_size, "users hash size, default = 64k");
static char nf_dest_buf[128] = "";
static char *nf_dest = nf_dest_buf;
module_param(nf_dest, charp, 0444);
MODULE_PARM_DESC(nf_dest, "Netflow v9 collectors (addr1:port1[,addr2:port2]), default = none");
u_int32_t nat_htable_vector = 0;
u_int32_t users_htable_vector = 0;
static spinlock_t *create_session_lock;
static DEFINE_SPINLOCK(sessions_timer_lock);
static DEFINE_SPINLOCK(users_timer_lock);
static struct timer_list sessions_cleanup_timer, users_cleanup_timer, nf_send_timer;
struct proc_dir_entry *proc_net_nat;
struct netflow_sock {
struct list_head list;
struct socket *sock;
struct sockaddr_storage addr; // destination
};
struct xt_nat_htable {
uint8_t use;
spinlock_t lock;
struct hlist_head session;
};
struct nat_htable_ent {
struct rcu_head rcu;
struct hlist_node list_node;
uint8_t proto;
uint32_t addr;
uint16_t port;
struct nat_session *data;
};
struct nat_session {
uint32_t in_addr;
uint32_t dst_addr;
uint16_t dst_port;
uint16_t in_port;
uint16_t out_port;
int16_t timeout;
uint8_t flags;
};
struct xt_users_htable {
uint8_t use;
spinlock_t lock;
struct hlist_head user;
};
struct user_htable_ent {
struct rcu_head rcu;
struct hlist_node list_node;
uint32_t addr;
uint16_t tcp_count;
uint16_t udp_count;
uint16_t other_count;
uint8_t idle;
};
struct xt_users_htable *ht_users;
static u_int32_t nat_pool_start;
static u_int32_t nat_pool_end;
struct xt_nat_htable *ht_inner, *ht_outer;
static char *print_sockaddr(const struct sockaddr_storage *ss)
{
static char buf[64];
snprintf(buf, sizeof(buf), "%pISpc", ss);
return buf;
}
static inline long timer_end(struct timespec64 start_time)
{
struct timespec64 end_time;
ktime_get_raw_ts64(&end_time);
return(end_time.tv_nsec - start_time.tv_nsec);
}
static inline struct timespec64 timer_start(void)
{
struct timespec64 start_time;
ktime_get_raw_ts64(&start_time);
return start_time;
}
static inline u_int32_t
get_pool_size(void)
{
return ntohl(nat_pool_end)-ntohl(nat_pool_start)+1;
}
static inline u_int32_t
get_nat_addr(const u_int32_t addr)
{
return htonl(ntohl(nat_pool_start)+reciprocal_scale(jhash_1word(addr, 0), get_pool_size()));
}
static inline u_int32_t
get_hash_nat_ent(const uint8_t proto, const u_int32_t addr, const uint16_t port)
{
return reciprocal_scale(jhash_3words((u32)proto, addr, (u32)port, 0), nat_hash_size);
}
static inline u_int32_t
get_hash_user_ent(const u_int32_t addr)
{
return reciprocal_scale(jhash_1word(addr, 0), users_hash_size);
}
static inline u_int32_t pool_table_create(void)
{
unsigned int sz; /* (bytes) */
unsigned int pool_size;
int i;
pool_size = get_pool_size();
sz = sizeof(spinlock_t) * pool_size;
create_session_lock = kzalloc(sz, GFP_KERNEL);
if (create_session_lock == NULL)
return -ENOMEM;
for (i = 0; i < pool_size; i++) {
spin_lock_init(&create_session_lock[i]);
}
printk(KERN_INFO "xt_NAT DEBUG: nat pool table mem: %d\n", sz);
return 0;
}
void pool_table_remove(void)
{
kfree(create_session_lock);
printk(KERN_INFO "xt_NAT pool_table_remove DEBUG: removed\n");
}
static int users_htable_create(void)
{
unsigned int sz; /* (bytes) */
int i;
sz = sizeof(struct xt_users_htable) * users_hash_size;
ht_users = kzalloc(sz, GFP_KERNEL);
if (ht_users == NULL)
return -ENOMEM;
for (i = 0; i < users_hash_size; i++) {
spin_lock_init(&ht_users[i].lock);
INIT_HLIST_HEAD(&ht_users[i].user);
ht_users[i].use = 0;
}
printk(KERN_INFO "xt_NAT DEBUG: users htable mem: %d\n", sz);
return 0;
}
void users_htable_remove(void)
{
struct user_htable_ent *user;
struct hlist_head *head;
struct hlist_node *next;
int i;
for (i = 0; i < users_hash_size; i++) {
spin_lock_bh(&ht_users[i].lock);
head = &ht_users[i].user;
hlist_for_each_entry_safe(user, next, head, list_node) {
hlist_del_rcu(&user->list_node);
ht_users[i].use--;
kfree_rcu(user, rcu);
}
if (ht_users[i].use != 0) {
printk(KERN_WARNING "xt_NAT users_htable_remove ERROR: bad use value: %d in element %d\n", ht_users[i].use, i);
}
spin_unlock_bh(&ht_users[i].lock);
}
kfree(ht_users);
printk(KERN_INFO "xt_NAT users_htable_remove DONE\n");
return;
}
void nat_htable_remove(void)
{
struct nat_htable_ent *session;
struct hlist_head *head;
struct hlist_node *next;
unsigned int i;
void *p;
for (i = 0; i < nat_hash_size; i++) {
spin_lock_bh(&ht_inner[i].lock);
head = &ht_inner[i].session;
hlist_for_each_entry_safe(session, next, head, list_node) {
hlist_del_rcu(&session->list_node);
ht_inner[i].use--;
kfree_rcu(session, rcu);
}
if (ht_inner[i].use != 0) {
printk(KERN_WARNING "xt_NAT nat_htable_remove inner ERROR: bad use value: %d in element %d\n", ht_inner[i].use, i);
}
spin_unlock_bh(&ht_inner[i].lock);
}
for (i = 0; i < nat_hash_size; i++) {
spin_lock_bh(&ht_outer[i].lock);
head = &ht_outer[i].session;
hlist_for_each_entry_safe(session, next, head, list_node) {
hlist_del_rcu(&session->list_node);
ht_outer[i].use--;
p = session->data;
kfree_rcu(session, rcu);
kfree(p);
}
if (ht_outer[i].use != 0) {
printk(KERN_WARNING "xt_NAT nat_htable_remove outer ERROR: bad use value: %d in element %d\n", ht_outer[i].use, i);
}
spin_unlock_bh(&ht_outer[i].lock);
}
printk(KERN_INFO "xt_NAT nat_htable_remove DONE\n");
return;
}
static int nat_htable_create(void)
{
unsigned int sz; /* (bytes) */
int i;
sz = sizeof(struct xt_nat_htable) * nat_hash_size;
ht_inner = kzalloc(sz, GFP_KERNEL);
if (ht_inner == NULL)
return -ENOMEM;
for (i = 0; i < nat_hash_size; i++) {
spin_lock_init(&ht_inner[i].lock);
INIT_HLIST_HEAD(&ht_inner[i].session);
ht_inner[i].use = 0;
}
printk(KERN_INFO "xt_NAT DEBUG: sessions htable inner mem: %d\n", sz);
ht_outer = kzalloc(sz, GFP_KERNEL);
if (ht_outer == NULL)
return -ENOMEM;
for (i = 0; i < nat_hash_size; i++) {
spin_lock_init(&ht_outer[i].lock);
INIT_HLIST_HEAD(&ht_outer[i].session);
ht_outer[i].use = 0;
}
printk(KERN_INFO "xt_NAT DEBUG: sessions htable outer mem: %d\n", sz);
return 0;
}
struct nat_htable_ent *lookup_session(struct xt_nat_htable *ht, const uint8_t proto, const u_int32_t addr, const uint16_t port)
{
struct nat_htable_ent *session;
struct hlist_head *head;
unsigned int hash;
hash = get_hash_nat_ent(proto, addr, port);
if (ht[hash].use == 0)
return NULL;
head = &ht[hash].session;
hlist_for_each_entry_rcu(session, head, list_node) {
if (session->addr == addr && session->port == port && session->proto == proto && session->data->timeout > 0) {
return session;
}
}
return NULL;
}
static uint16_t search_free_l4_port(const uint8_t proto, const u_int32_t nataddr, const uint16_t userport)
{
uint16_t i, freeport;
for(i = 0; i < 64512; i++) {
freeport = ntohs(userport) + i;
if (freeport < 1024) {
freeport += 1024;
}
if(!lookup_session(ht_outer, proto, nataddr, htons(freeport))) {
return htons(freeport);
}
}
return 0;
}
static int check_user_limits(const u_int8_t proto, const u_int32_t addr)
{
struct user_htable_ent *user;
struct hlist_head *head;
unsigned int hash, is_found, ret;
unsigned int sessions, session_limit;
hash = get_hash_user_ent(addr);
rcu_read_lock_bh();
head = &ht_users[hash].user;
is_found=0;
hlist_for_each_entry_rcu(user, head, list_node) {
if (user->addr == addr && user->idle < 15) {
if (proto == IPPROTO_TCP) {
sessions = user->tcp_count;
session_limit = 4096;
} else if (proto == IPPROTO_UDP) {
sessions = user->udp_count;
session_limit = 4096;
} else {
sessions = user->other_count;
session_limit = 4096;
}
is_found=1;
break;
}
}
ret=1;
if (is_found==1) {
if (sessions < session_limit) {
ret=1;
} else {
ret=0;
}
} else {
ret=1;
}
rcu_read_unlock_bh();
return ret;
}
void update_user_limits(const u_int8_t proto, const u_int32_t addr, const int8_t operation)
{
struct user_htable_ent *user;
struct hlist_head *head;
unsigned int hash, is_found;
unsigned int sz;
hash = get_hash_user_ent(addr);
spin_lock_bh(&ht_users[hash].lock);
head = &ht_users[hash].user;
is_found=0;
hlist_for_each_entry(user, head, list_node) {
if (user->addr == addr && user->idle < 15) {
is_found=1;
break;
}
}
if (likely(is_found==1)) {
user->idle = 0;
if (proto == IPPROTO_TCP) {
user->tcp_count += operation;
} else if (proto == IPPROTO_UDP) {
user->udp_count += operation;
} else {
user->other_count += operation;
}
} else {
sz = sizeof(struct user_htable_ent);
user = kzalloc(sz, GFP_ATOMIC);
if (user == NULL) {
printk(KERN_WARNING "xt_NAT update_user_limits ERROR: Cannot allocate memory for user_session\n");
spin_unlock_bh(&ht_users[hash].lock);
return;
}
user->addr = addr;
user->tcp_count = 0;
user->udp_count = 0;
user->other_count = 0;
user->idle = 0;
if (proto == IPPROTO_TCP) {
user->tcp_count += operation;
} else if (proto == IPPROTO_UDP) {
user->udp_count += operation;
} else {
user->other_count += operation;
}
hlist_add_head_rcu(&user->list_node, &ht_users[hash].user);
ht_users[hash].use++;
atomic64_inc(&users_active);
}
spin_unlock_bh(&ht_users[hash].lock);
return;
}
/* socket code */
static void sk_error_report(struct sock *sk)
{
sk->sk_err = 0;
return;
}
static struct socket *usock_open_sock(const struct sockaddr_storage *addr, void *user_data)
{
struct socket *sock;
int error;
if ((error = sock_create_kern(addr->ss_family, SOCK_DGRAM, IPPROTO_UDP, &sock)) < 0) {
printk(KERN_WARNING "xt_NAT NEL: sock_create_kern error %d\n", -error);
return NULL;
}
sock->sk->sk_allocation = GFP_ATOMIC;
sock->sk->sk_prot->unhash(sock->sk); /* hidden from input */
sock->sk->sk_error_report = &sk_error_report; /* clear ECONNREFUSED */
sock->sk->sk_user_data = user_data; /* usock */
if (sndbuf < SOCK_MIN_SNDBUF)
sndbuf = SOCK_MIN_SNDBUF;
if (sndbuf)
sock->sk->sk_sndbuf = sndbuf;
else
sndbuf = sock->sk->sk_sndbuf;
error = sock->ops->connect(sock, (struct sockaddr *)addr, sizeof(*addr), 0);
if (error < 0) {
printk(KERN_WARNING "xt_NAT NEL: error connecting UDP socket %d,"
" don't worry, will try reconnect later.\n", -error);
/* ENETUNREACH when no interfaces */
sock_release(sock);
return NULL;
}
return sock;
}
static void netflow_sendmsg(void *buffer, const int len)
{
struct msghdr msg = { .msg_flags = MSG_DONTWAIT|MSG_NOSIGNAL };
struct kvec iov = { buffer, len };
struct netflow_sock *usock;
int ret;
list_for_each_entry(usock, &usock_list, list) {
if (!usock->sock)
usock->sock = usock_open_sock(&usock->addr, usock);
if (!usock->sock)
continue;
ret = kernel_sendmsg(usock->sock, &msg, &iov, 1, (size_t)len);
if (ret == -EINVAL) {
if (usock->sock)
sock_release(usock->sock);
usock->sock = NULL;
} else if (ret == -EAGAIN) {
printk(KERN_WARNING "xt_NAT NEL: increase sndbuf!\n");
}
}
}
static void netflow_export_pdu_v9(void)
{
struct timespec64 ts;
int pdusize;
if (!pdu_data_records)
return;
pdu.version = htons(9);
pdu.nr_records = htons(pdu_data_records + 1);
pdu.ts_uptime = htonl(jiffies_to_msecs(jiffies));
ktime_get_real_ts64(&ts);
pdu.ts_usecs = htonl(ts.tv_sec);
pdu.seq = htonl(pdu_seq);
pdu.srcID = 0;
pdu.template_V9 = templateV9;
pdu.FlowSetId = htons(flowsetID);
pdu.FlowSetIdSize = sizeof(struct netflow9_record) * pdu_data_records;
pdusize = NETFLOW9_HEADER_SIZE + pdu.FlowSetIdSize;
pdu.FlowSetIdSize = htons(pdu.FlowSetIdSize+4);
netflow_sendmsg(&pdu, pdusize);
pdu_seq++;
pdu_data_records = 0;
}
static void netflow_export_flow_v9(const uint8_t proto, const u_int32_t srcaddr, const uint16_t srcport, const u_int32_t dstaddr, const uint16_t dstport, const u_int32_t nataddr, const uint16_t natport, const int nat_event)
{
struct netflow9_record *rec;
spin_lock_bh(&nfsend_lock);
rec = &pdu.flow[pdu_data_records++];
rec->protocol = proto;
rec->s_port = srcport;
rec->s_addr = srcaddr;
rec->d_port = dstport;
rec->d_addr = dstaddr;
rec->n_addr = nataddr;
rec->n_port = natport;
rec->event = nat_event;
if (pdu_data_records == NETFLOW9_RECORDS_MAX)
netflow_export_pdu_v9();
spin_unlock_bh(&nfsend_lock);
}
struct nat_htable_ent *create_nat_session(const uint8_t proto, const u_int32_t useraddr, const uint16_t userport, const u_int32_t dstaddr, const uint16_t dstport, const u_int32_t nataddr)
{
unsigned int hash;
struct nat_htable_ent *session, *session2;
struct nat_session *data_session;
uint16_t natport;
unsigned int sz;
unsigned int nataddr_id;
atomic64_inc(&sessions_tried);
if (unlikely(check_user_limits(proto, useraddr) == 0)) {
printk(KERN_NOTICE "xt_NAT: %pI4 exceed max allowed sessions\n", &useraddr);
return NULL;
}
nataddr_id = ntohl(nataddr) - ntohl(nat_pool_start);
spin_lock_bh(&create_session_lock[nataddr_id]);
rcu_read_lock_bh();
session = lookup_session(ht_inner, proto, useraddr, userport);
if(unlikely(session)) {
spin_unlock_bh(&create_session_lock[nataddr_id]);
return lookup_session(ht_outer, proto, nataddr, session->data->out_port);
}
rcu_read_unlock_bh();
if (likely(proto == IPPROTO_TCP || proto == IPPROTO_UDP || proto == IPPROTO_ICMP)) {
rcu_read_lock_bh();
natport = search_free_l4_port(proto, nataddr, userport);
rcu_read_unlock_bh();
if (natport == 0) {
printk(KERN_WARNING "xt_NAT create_nat_session ERROR: Not found free nat port for %d %pI4:%u -> %pI4:XXXX\n", proto, &useraddr, userport, &nataddr);
spin_unlock_bh(&create_session_lock[nataddr_id]);
return NULL;
}
} else {
natport = userport;
}
sz = sizeof(struct nat_session);
data_session = kzalloc(sz, GFP_ATOMIC);
if (unlikely(data_session == NULL)) {
printk(KERN_WARNING "xt_NAT create_nat_session ERROR: Cannot allocate memory for data_session\n");
spin_unlock_bh(&create_session_lock[nataddr_id]);
return NULL;
}
sz = sizeof(struct nat_htable_ent);
session = kzalloc(sz, GFP_ATOMIC);
if (unlikely(session == NULL)) {
printk(KERN_WARNING "xt_NAT ERROR: Cannot allocate memory for ht_inner session\n");
kfree(data_session);
spin_unlock_bh(&create_session_lock[nataddr_id]);
return NULL;
}
sz = sizeof(struct nat_htable_ent);
session2 = kzalloc(sz, GFP_ATOMIC);
if (unlikely(session2 == NULL)) {
printk(KERN_WARNING "xt_NAT ERROR: Cannot allocate memory for ht_outer session\n");
kfree(data_session);
kfree(session);
spin_unlock_bh(&create_session_lock[nataddr_id]);
return NULL;
}
data_session->in_addr = useraddr;
data_session->in_port = userport;
data_session->out_port = natport;
data_session->dst_addr = dstaddr;
data_session->dst_port = dstport;
data_session->timeout = 30;
data_session->flags = 0;
session->proto = proto;
session->addr = useraddr;
session->port = userport;
session->data = data_session;
session2->proto = proto;
session2->addr = nataddr;
session2->port = natport;
session2->data = data_session;
hash = get_hash_nat_ent(proto, useraddr, userport);
spin_lock_bh(&ht_inner[hash].lock);
hlist_add_head_rcu(&session->list_node, &ht_inner[hash].session);
ht_inner[hash].use++;
spin_unlock_bh(&ht_inner[hash].lock);
hash = get_hash_nat_ent(proto, nataddr, natport);
spin_lock_bh(&ht_outer[hash].lock);
hlist_add_head_rcu(&session2->list_node, &ht_outer[hash].session);
ht_outer[hash].use++;
spin_unlock_bh(&ht_outer[hash].lock);
spin_unlock_bh(&create_session_lock[nataddr_id]);
update_user_limits(proto, useraddr, 1);
netflow_export_flow_v9(proto, useraddr, userport, dstaddr, dstport, nataddr, natport, 1);
atomic64_inc(&sessions_created);
atomic64_inc(&sessions_active);
rcu_read_lock_bh();
return lookup_session(ht_outer, proto, nataddr, natport);
}
static unsigned int
nat_tg(struct sk_buff *skb, const struct xt_action_param *par)
{
struct iphdr *ip;
struct tcphdr *tcp;
struct udphdr *udp;
struct icmphdr *icmp;
struct nat_htable_ent *session;
uint32_t nat_addr;
uint16_t nat_port;
skb_frag_t *frag;
const struct xt_nat_tginfo *info = par->targinfo;
if (unlikely(skb->protocol != htons(ETH_P_IP))) {
printk(KERN_DEBUG "xt_NAT DEBUG: Drop not IP packet\n");
return NF_DROP;
}
if (unlikely(ip_hdrlen(skb) != sizeof(struct iphdr))) {
printk(KERN_DEBUG "xt_NAT DEBUG: Drop truncated IP packet\n");
return NF_DROP;
}
ip = (struct iphdr *)skb_network_header(skb);
if (unlikely(ip->frag_off & htons(IP_OFFSET))) {
printk(KERN_DEBUG "xt_NAT DEBUG: Drop fragmented IP packet\n");
return NF_DROP;
}
if (unlikely(ip->version != 4)) {
printk(KERN_DEBUG "xt_NAT DEBUG: Drop not IPv4 IP packet\n");
return NF_DROP;
}
if (info->variant == XTNAT_SNAT) {
nat_addr = get_nat_addr(ip->saddr);
if (ip->protocol == IPPROTO_TCP) {
if (unlikely(skb->len < ip_hdrlen(skb) + sizeof(struct tcphdr))) {
printk(KERN_DEBUG "xt_NAT SNAT: Drop truncated TCP packet\n");
return NF_DROP;
}
skb_set_transport_header(skb, ip->ihl * 4);
tcp = (struct tcphdr *)skb_transport_header(skb);
skb_reset_transport_header(skb);
rcu_read_lock_bh();
session = lookup_session(ht_inner, ip->protocol, ip->saddr, tcp->source);
if (session) {
csum_replace4(&ip->check, ip->saddr, nat_addr);
inet_proto_csum_replace4(&tcp->check, skb, ip->saddr, nat_addr, true);
inet_proto_csum_replace2(&tcp->check, skb, tcp->source, session->data->out_port, true);
ip->saddr = nat_addr;
tcp->source = session->data->out_port;
if (tcp->fin || tcp->rst) {
session->data->timeout=10;
session->data->flags |= FLAG_TCP_FIN;
} else if (session->data->flags & FLAG_TCP_FIN) {
session->data->timeout=10;
session->data->flags &= ~FLAG_TCP_FIN;
} else if ((session->data->flags & FLAG_REPLIED) == 0) {
session->data->timeout=30;
} else {
session->data->timeout=300;
}
rcu_read_unlock_bh();
} else {
rcu_read_unlock_bh();
session = create_nat_session(ip->protocol, ip->saddr, tcp->source, ip->daddr, tcp->dest, nat_addr);
if (session == NULL) {
return NF_DROP;
}
csum_replace4(&ip->check, ip->saddr, session->addr);
inet_proto_csum_replace4(&tcp->check, skb, ip->saddr, session->addr, true);
inet_proto_csum_replace2(&tcp->check, skb, session->data->in_port, session->data->out_port, true);
ip->saddr = session->addr;
tcp->source = session->data->out_port;
rcu_read_unlock_bh();
}
} else if (ip->protocol == IPPROTO_UDP) {
if (unlikely(skb->len < ip_hdrlen(skb) + sizeof(struct udphdr))) {
printk(KERN_DEBUG "xt_NAT SNAT: Drop truncated UDP packet\n");
return NF_DROP;
}
skb_set_transport_header(skb, ip->ihl * 4);
udp = (struct udphdr *)skb_transport_header(skb);
skb_reset_transport_header(skb);
rcu_read_lock_bh();
session = lookup_session(ht_inner, ip->protocol, ip->saddr, udp->source);
if (session) {
csum_replace4(&ip->check, ip->saddr, nat_addr);
if (udp->check) {
inet_proto_csum_replace4(&udp->check, skb, ip->saddr, nat_addr, true);
inet_proto_csum_replace2(&udp->check, skb, udp->source, session->data->out_port, true);
}
ip->saddr = nat_addr;
udp->source = session->data->out_port;
if ((session->data->flags & FLAG_REPLIED) == 0) {
session->data->timeout=30;
} else {
session->data->timeout=300;
}
rcu_read_unlock_bh();
} else {
rcu_read_unlock_bh();
session = create_nat_session(ip->protocol, ip->saddr, udp->source, ip->daddr, udp->dest, nat_addr);
if (session == NULL) {
return NF_DROP;
}
csum_replace4(&ip->check, ip->saddr, session->addr);
if (udp->check) {
inet_proto_csum_replace4(&udp->check, skb, ip->saddr, session->addr, true);
inet_proto_csum_replace2(&udp->check, skb, session->data->in_port, session->data->out_port, true);
}
ip->saddr = session->addr;
udp->source = session->data->out_port;
rcu_read_unlock_bh();
}
} else if (ip->protocol == IPPROTO_ICMP) {
if (unlikely(skb->len < ip_hdrlen(skb) + sizeof(struct icmphdr))) {
printk(KERN_DEBUG "xt_NAT SNAT: Drop truncated ICMP packet\n");
return NF_DROP;
}
skb_set_transport_header(skb, ip->ihl * 4);
icmp = (struct icmphdr *)skb_transport_header(skb);
skb_reset_transport_header(skb);
nat_port = 0;
if (icmp->type == 0 || icmp->type == 8) {
nat_port = icmp->un.echo.id;
}
rcu_read_lock_bh();
session = lookup_session(ht_inner, ip->protocol, ip->saddr, nat_port);
if (session) {
csum_replace4(&ip->check, ip->saddr, nat_addr);
ip->saddr = nat_addr;
if (icmp->type == 0 || icmp->type == 8) {
inet_proto_csum_replace2(&icmp->checksum, skb, nat_port, session->data->out_port, true);
icmp->un.echo.id = session->data->out_port;
}
session->data->timeout=30;
rcu_read_unlock_bh();
} else {
rcu_read_unlock_bh();
session = create_nat_session(ip->protocol, ip->saddr, nat_port, ip->daddr, nat_port, nat_addr);
if (session == NULL) {
return NF_DROP;
}
csum_replace4(&ip->check, ip->saddr, session->addr);
ip->saddr = session->addr;
if (icmp->type == 0 || icmp->type == 8) {
inet_proto_csum_replace2(&icmp->checksum, skb, nat_port, session->data->out_port, true);
icmp->un.echo.id = session->data->out_port;
}
rcu_read_unlock_bh();
}
} else {
rcu_read_lock_bh();
session = lookup_session(ht_inner, ip->protocol, ip->saddr, 0);
if (session) {
csum_replace4(&ip->check, ip->saddr, nat_addr);
ip->saddr = nat_addr;
if ((session->data->flags & FLAG_REPLIED) == 0) {
session->data->timeout=30;
} else {
session->data->timeout=300;
}
rcu_read_unlock_bh();
} else {
rcu_read_unlock_bh();
session = create_nat_session(ip->protocol, ip->saddr, 0, ip->daddr, 0, nat_addr);
if (session == NULL) {
return NF_DROP;
}
csum_replace4(&ip->check, ip->saddr, session->addr);
ip->saddr = session->addr;
rcu_read_unlock_bh();
}
}
} else if (info->variant == XTNAT_DNAT) {
if (ip->protocol == IPPROTO_TCP) {
if (unlikely(skb->len < ip_hdrlen(skb) + sizeof(struct tcphdr))) {
printk(KERN_DEBUG "xt_NAT DNAT: Drop truncated TCP packet\n");
return NF_DROP;
}
skb_set_transport_header(skb, ip->ihl * 4);
tcp = (struct tcphdr *)skb_transport_header(skb);
skb_reset_transport_header(skb);
if (unlikely(skb_shinfo(skb)->nr_frags > 1 && skb_headlen(skb) == sizeof(struct iphdr))) {
frag = &skb_shinfo(skb)->frags[0];
if (unlikely(skb_frag_size(frag) < sizeof(struct tcphdr))) {
printk(KERN_DEBUG "xt_NAT DNAT: drop TCP frag_size = %d\n", skb_frag_size(frag));
return NF_DROP;
}
tcp = (struct tcphdr *)skb_frag_address_safe(frag);
if (unlikely(tcp == NULL)) {
printk(KERN_DEBUG "xt_NAT DNAT: drop fragmented TCP\n");
return NF_DROP;
}
atomic64_inc(&frags);
}
rcu_read_lock_bh();
session = lookup_session(ht_outer, ip->protocol, ip->daddr, tcp->dest);
if (likely(session)) {
skb_reset_transport_header(skb);
csum_replace4(&ip->check, ip->daddr, session->data->in_addr);
inet_proto_csum_replace4(&tcp->check, skb, ip->daddr, session->data->in_addr, true);
inet_proto_csum_replace2(&tcp->check, skb, tcp->dest, session->data->in_port, true);
ip->daddr = session->data->in_addr;
tcp->dest = session->data->in_port;
if (tcp->fin || tcp->rst) {
session->data->timeout=10;
session->data->flags |= FLAG_TCP_FIN;
} else if (session->data->flags & FLAG_TCP_FIN) {
session->data->timeout=10;
session->data->flags &= ~FLAG_TCP_FIN;
} else if ((session->data->flags & FLAG_REPLIED) == 0) {
session->data->timeout=300;
session->data->flags |= FLAG_REPLIED;
}
rcu_read_unlock_bh();
} else {
rcu_read_unlock_bh();
atomic64_inc(&dnat_dropped);
}
} else if (ip->protocol == IPPROTO_UDP) {
if (unlikely(skb->len < ip_hdrlen(skb) + sizeof(struct udphdr))) {
printk(KERN_DEBUG "xt_NAT DNAT: Drop truncated UDP packet\n");
return NF_DROP;
}
skb_set_transport_header(skb, ip->ihl * 4);
udp = (struct udphdr *)skb_transport_header(skb);
if (unlikely(skb_shinfo(skb)->nr_frags > 1 && skb_headlen(skb) == sizeof(struct iphdr))) {
frag = &skb_shinfo(skb)->frags[0];
if (unlikely(skb_frag_size(frag) < sizeof(struct udphdr))) {
printk(KERN_DEBUG "xt_NAT DNAT: drop UDP frag_size = %d\n", skb_frag_size(frag));
return NF_DROP;
}
udp = (struct udphdr *)skb_frag_address_safe(frag);
if (unlikely(udp == NULL)) {
printk(KERN_DEBUG "xt_NAT DNAT: drop fragmented UDP\n");
return NF_DROP;
}
atomic64_inc(&frags);
}
rcu_read_lock_bh();
session = lookup_session(ht_outer, ip->protocol, ip->daddr, udp->dest);
if (likely(session)) {
skb_reset_transport_header(skb);
csum_replace4(&ip->check, ip->daddr, session->data->in_addr);
if (udp->check) {
inet_proto_csum_replace4(&udp->check, skb, ip->daddr, session->data->in_addr, true);
inet_proto_csum_replace2(&udp->check, skb, udp->dest, session->data->in_port, true);
}
ip->daddr = session->data->in_addr;
udp->dest = session->data->in_port;
if ((session->data->flags & FLAG_REPLIED) == 0) {
session->data->timeout=300;
session->data->flags |= FLAG_REPLIED;
}
rcu_read_unlock_bh();
} else {
rcu_read_unlock_bh();
atomic64_inc(&dnat_dropped);
}
} else if (ip->protocol == IPPROTO_ICMP) {
if (unlikely(skb->len < ip_hdrlen(skb) + sizeof(struct icmphdr))) {
printk(KERN_DEBUG "xt_NAT DNAT: Drop truncated ICMP packet\n");
return NF_DROP;
}
skb_set_transport_header(skb, ip->ihl * 4);
icmp = (struct icmphdr *)skb_transport_header(skb);
nat_port = 0;
if (icmp->type == 0 || icmp->type == 8) {
nat_port = icmp->un.echo.id;
} else if (icmp->type == 3 || icmp->type == 4 || icmp->type == 5 || icmp->type == 11 || icmp->type == 12 || icmp->type == 31) {
atomic64_inc(&related_icmp);
if (skb->len < ip_hdrlen(skb) + sizeof(struct icmphdr) + sizeof(struct iphdr)) {
printk(KERN_DEBUG "xt_NAT DNAT: Drop related ICMP packet witch truncated IP header\n");
return NF_DROP;
}
skb_set_network_header(skb,sizeof(struct icmphdr) + sizeof(struct iphdr));
ip = (struct iphdr *)skb_network_header(skb);
skb_reset_network_header(skb);
if (ip->protocol == IPPROTO_TCP) {
if (skb->len < ip_hdrlen(skb) + sizeof(struct icmphdr) + sizeof(struct iphdr) + 8) {
printk(KERN_DEBUG "xt_NAT DNAT: Drop related ICMP packet witch truncated TCP header\n");
return NF_DROP;
}
skb_set_transport_header(skb, (ip->ihl * 4) + sizeof(struct icmphdr) + sizeof(struct iphdr));
tcp = (struct tcphdr *)skb_transport_header(skb);
skb_reset_transport_header(skb);
rcu_read_lock_bh();
session = lookup_session(ht_outer, ip->protocol, ip->saddr, tcp->source);
if (session) {
csum_replace4(&ip->check, ip->saddr, session->data->in_addr);
ip->saddr = session->data->in_addr;
tcp->source = session->data->in_port;
} else {