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pf4lin_main.c
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pf4lin_main.c
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/* $Id: pf4lin_main.c,v 1.24 2005/06/28 10:17:27 lars Exp $ */
#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/if_ether.h>
#include <linux/fs.h>
#include <linux/ip.h>
#include <linux/udp.h>
#include <linux/tcp.h>
#include <linux/in.h>
#include <linux/icmp.h>
#include <linux/skbuff.h>
#include <linux/netfilter_ipv4.h>
#include <linux/version.h>
#include "pf4linvar.h"
#include "pfvar.h"
#define DRV_VERSION "0.02"
MODULE_VERSION(DRV_VERSION);
MODULE_LICENSE("Dual BSD/GPL");
MODULE_AUTHOR("Lars Olsson, lo@abstractvoid.se");
MODULE_DESCRIPTION("OpenBSD's PF (Packet Filter) for Linux");
static int pf4lin_major = PF4LIN_MAJOR;
/* changed by DIOCTOGGLEDEBUG */
int debug = 0;
/* global variables */
struct rule *rulehead = NULL;
struct nat *nathead = NULL;
struct rdr *rdrhead = NULL;
struct state *statehead = NULL;
struct tree_node *tree_lan_ext = NULL,
*tree_ext_gwy = NULL;
struct timeval tv;
struct status status;
struct net_device *status_ifp = NULL;
u_int32_t last_purge = 0;
u_int16_t next_port_tcp = 50001,
next_port_udp = 50001;
int pf4lin_open(struct inode *inode, struct file *filp);
int pf4lin_close(struct inode *inode, struct file *filp);
int pf4lin_ioctl(struct inode *inode, struct file *filp,
unsigned int cmd, unsigned long arg);
void print_host(u_int32_t a, u_int16_t p);
void print_flags (u_int8_t f);
//void print_flags(struct tcphdr *th);
void print_state(int direction, struct state *s);
inline int match_addr(u_int8_t n, u_int32_t a, u_int32_t m, u_int32_t b);
inline int match_port(u_int8_t op, u_int16_t a1, u_int16_t a2, u_int16_t p);
struct nat *get_nat(const struct net_device *ifp, u_int8_t proto, u_int32_t addr);
struct rdr *get_rdr(const struct net_device *ifp, u_int8_t proto, u_int32_t addr, u_int16_t port);
inline signed char tree_key_compare(struct tree_key *a, struct tree_key *b);
inline void tree_rotate_left(struct tree_node **p);
inline void tree_rotate_right(struct tree_node **p);
int tree_insert(struct tree_node **p, struct tree_key *key, struct state *state);
int tree_remove(struct tree_node **p, struct tree_key *key);
inline struct state *find_state(struct tree_node *p, struct tree_key *key);
void insert_state(struct state *state);
void purge_expired_states(void);
inline u_short fix(u_short cksum, u_short old, u_short new);
void change_ap(u_int32_t *a, u_int16_t *p, u_int16_t *ic, u_int16_t *pc, u_int32_t an,
u_int16_t pn);
void change_a(u_int32_t *a, u_int16_t *c, u_int32_t an);
void change_icmp(u_int32_t *ia, u_int16_t *ip, u_int32_t *oa, u_int32_t na,
u_int16_t np, u_int16_t *pc, u_int16_t *h2c, u_int16_t *ic, u_int16_t *hc);
void send_reset(int direction, const struct net_device *ifp, struct iphdr *h, struct tcphdr *th);
int pf4lin_test_flags(struct tcphdr *th, u_int8_t flagset, u_int8_t flags);
struct state *pf_test_state_tcp(int direction, const struct net_device *ifp,
struct iphdr *h, struct tcphdr *th);
int pf_test_tcp(int direction, const struct net_device *ifp, struct iphdr *h, struct tcphdr *th);
struct state *pf_test_state_udp(int direction, const struct net_device *ifp,
struct iphdr *h, struct udphdr *uh);
int pf_test_udp(int direction, const struct net_device *ifp, struct iphdr *h, struct udphdr *uh);
struct state *pf_test_state_icmp(int direction, const struct net_device *ifp,
struct iphdr *h, struct icmphdr *ih);
int pf_test_icmp(int direction, const struct net_device *ifp, struct iphdr *h, struct icmphdr *ih);
static unsigned int pf4lin_hook(unsigned int hook, struct sk_buff **pskb, const struct net_device *indev,
const struct net_device *outdev, int (*okfn)(struct sk_buff *));
/* --------------------------------------------------------------------------*/
int
pf4lin_open(struct inode *inode, struct file *filp)
{
DEBUGMSG("open\n");
return 0;
}
int
pf4lin_close(struct inode *inode, struct file *filp)
{
DEBUGMSG("close\n");
return 0;
}
spinlock_t driver_lock = SPIN_LOCK_UNLOCKED;
int
pf4lin_ioctl(struct inode *inode, struct file *filp,
unsigned int cmd, unsigned long arg)
{
int error = NO_ERROR;
struct ioctlbuffer *ub = NULL;
void *kb = NULL;
// unsigned long flags;
if(_IOC_TYPE(cmd) != PF_IOC_MAGIC)
return -ENOTTY;
if(_IOC_NR(cmd) > PF_IOC_MAXNR)
return -ENOTTY;
if (_IOC_DIR(cmd) & _IOC_READ)
error = !access_ok(VERIFY_WRITE, (void *)arg, _IOC_SIZE(cmd));
else if (_IOC_DIR(cmd) & _IOC_WRITE)
error = !access_ok(VERIFY_READ, (void *)arg, _IOC_SIZE(cmd));
if (error) return -EFAULT;
if((cmd != DIOCSTART) && (cmd != DIOCSTOP) &&
(cmd != DIOCCLRSTATES) && (cmd != DIOCTOGGLEDEBUG)){
ub = (struct ioctlbuffer *)arg;
if (ub == NULL)
return ERROR_INVALID_PARAMETERS;
kb = kmalloc(ub->size, GFP_ATOMIC);
if (kb == NULL)
return ERROR_MALLOC;
if (copy_from_user(kb, ub->buffer, ub->size)) {
kfree(kb);
return ERROR_INVALID_PARAMETERS;
}
}
/* disable interrupts */
//save_flags(flags);
//cli();
spin_lock_irq(&driver_lock);
do_gettimeofday(&tv);
if (tv.tv_sec - last_purge >= 10) {
purge_expired_states();
last_purge = tv.tv_sec;
}
switch(cmd){
case DIOCSTART:
DEBUGMSG("DIOCSTART\n");
if(status.running)
error = ERROR_ALREADY_RUNNING;
else{
u_int32_t states = status.states;
memset(&status, 0, sizeof(struct status));
status.running = 1;
status.states = states;
INFO("started\n");
}
break;
case DIOCSTOP:
DEBUGMSG("DIOCSTOP\n");
if (!status.running)
error = ERROR_NOT_RUNNING;
else {
status.running = 0;
INFO("packetfilter: stopped\n");
}
break;
case DIOCSETRULES:{
struct rule *rules = (struct rule *)kb, *ruletail = NULL;
u_int16_t n;
DEBUGMSG("DIOCSETRULES\n");
while (rulehead != NULL) {
struct rule *next = rulehead->next;
kfree(rulehead);
rulehead = next;
}
for (n = 0; n < ub->entries; ++n) {
struct rule *rule;
rule = kmalloc(sizeof(struct rule), GFP_ATOMIC);
if (rule == NULL) {
error = ERROR_MALLOC;
goto done;
}
memcpy(rule, rules + n, sizeof(struct rule));
rule->ifp = NULL;
if (rule->ifname[0]) {
rule->ifp = dev_get_by_name(rule->ifname);
if (rule->ifp == NULL) {
kfree(rule);
error = ERROR_INVALID_PARAMETERS;
goto done;
}
}
rule->next = NULL;
if (ruletail != NULL) {
ruletail->next = rule;
ruletail = rule;
} else
rulehead = ruletail = rule;
}
break;
}
case DIOCGETRULES: {
struct rule *rules = (struct rule *)kb;
struct rule *rule = rulehead;
u_int16_t n = 0;
DEBUGMSG("DIOCGETRULES\n");
while ((rule != NULL) && (n < ub->entries)) {
memcpy(rules + n, rule, sizeof(struct rule));
n++;
rule = rule->next;
}
ub->entries = n;
break;
}
case DIOCSETNAT:{
struct nat *nats = (struct nat *)kb;
u_int16_t n;
DEBUGMSG("DIOCSETNAT\n");
while (nathead != NULL) {
struct nat *next = nathead->next;
kfree(nathead);
nathead = next;
}
for (n = 0; n < ub->entries; ++n) {
struct nat *nat;
nat = kmalloc(sizeof(struct nat), GFP_ATOMIC);
if (nat == NULL) {
error = ERROR_MALLOC;
goto done;
}
memcpy(nat, nats + n, sizeof(struct nat));
nat->ifp = dev_get_by_name(nat->ifname);
if (nat->ifp == NULL) {
kfree(nat);
error = ERROR_INVALID_PARAMETERS;
goto done;
}
nat->next = nathead;
nathead = nat;
}
break;
}
case DIOCGETNAT:{
struct nat *nats = (struct nat *)kb;
struct nat *nat = nathead;
u_int16_t n = 0;
DEBUGMSG("DIOCGETNAT\n");
while ((nat != NULL) && (n < ub->entries)) {
memcpy(nats + n, nat, sizeof(struct nat));
n++;
nat = nat->next;
}
ub->entries = n;
break;
}
case DIOCSETRDR:{
struct rdr *rdrs = (struct rdr *)kb;
u_int16_t n;
DEBUGMSG("DIOCSETRDR\n");
while (rdrhead != NULL) {
struct rdr *next = rdrhead->next;
kfree(rdrhead);
rdrhead = next;
}
for (n = 0; n < ub->entries; ++n) {
struct rdr *rdr;
rdr = kmalloc(sizeof(struct rdr), GFP_ATOMIC);
if (rdr == NULL) {
error = ERROR_MALLOC;
goto done;
}
memcpy(rdr, rdrs + n, sizeof(struct rdr));
rdr->ifp = dev_get_by_name(rdr->ifname);
if (rdr->ifp == NULL) {
kfree(rdr);
error = ERROR_INVALID_PARAMETERS;
goto done;
}
rdr->next = rdrhead;
rdrhead = rdr;
}
break;
}
case DIOCGETRDR:{
struct rdr *rdrs = (struct rdr *)kb;
struct rdr *rdr = rdrhead;
u_int16_t n = 0;
DEBUGMSG("DIOCGETRDR\n");
while ((rdr != NULL) && (n < ub->entries)) {
memcpy(rdrs + n, rdr, sizeof(struct rdr));
n++;
rdr = rdr->next;
}
ub->entries = n;
break;
}
case DIOCCLRSTATES:{
struct state *state = statehead;
DEBUGMSG("DIOCCLRSTATES\n");
while (state != NULL) {
state->expire = 0;
state = state->next;
}
purge_expired_states();
break;
}
case DIOCGETSTATES:{
struct state *states = (struct state *)kb;
struct state *state;
u_int16_t n = 0;
DEBUGMSG("DIOCGETSTATES\n");
state = statehead;
while ((state != NULL) && (n < ub->entries)) {
printk("get state\n");
memcpy(states + n, state, sizeof(struct state));
states[n].creation = tv.tv_sec - states[n].creation;
if (states[n].expire <= tv.tv_sec)
states[n].expire = 0;
else
states[n].expire -= tv.tv_sec;
n++;
state = state->next;
}
ub->entries = n;
break;
}
case DIOCSETSTATUSIF:{
char *ifname = (char *)kb;
struct net_device *ifp = dev_get_by_name(ifname);
DEBUGMSG("DIOCSETSTATUSIF\n");
if (ifp == NULL)
error = ERROR_INVALID_PARAMETERS;
else
status_ifp = ifp;
break;
}
case DIOCGETSTATUS:{
struct status *st = (struct status *)kb;
u_int8_t running = status.running;
u_int32_t states = status.states;
DEBUGMSG("DIOCGETSTATUSIF\n");
memcpy(st, &status, sizeof(struct status));
st->since = st->since ? tv.tv_sec - st->since : 0;
ub->entries = 1;
memset(&status, 0, sizeof(struct status));
status.running = running;
status.states = states;
status.since = tv.tv_sec;
break;
}
case DIOCTOGGLEDEBUG:
DEBUGMSG("DIOCTOGGLEDEBUG\n");
if(debug)
debug = 0;
else
debug = 1;
INFO("debug is now:%s\n", (debug)? "ON" : "OFF");
break;
default:
DEBUGMSG("default ioctl - error\n");
error = ERROR_INVALID_OP;
break;
}
done:
/* enable interrupts */
// restore_flags(flags);
spin_unlock_irq(&driver_lock);
if (kb != NULL) {
if (copy_to_user(ub->buffer, kb, ub->size))
error = ERROR_INVALID_PARAMETERS;
kfree(kb);
}
return error;
}
/* --------------------------------------------------------------------------*/
void
print_host(u_int32_t a, u_int16_t p)
{
a = ntohl(a);
p = ntohs(p);
printk("%u.%u.%u.%u:%u", (a>>24)&255, (a>>16)&255, (a>>8)&255, a&255, p);
}
void
print_state(int direction, struct state *s)
{
print_host(s->lan.addr, s->lan.port);
printk(" ");
print_host(s->gwy.addr, s->gwy.port);
printk(" ");
print_host(s->ext.addr, s->ext.port);
printk(" [%lu+%lu]", (long unsigned int)(s->src.seqlo), (long unsigned int)(s->src.seqhi - s->src.seqlo));
printk(" [%lu+%lu]", (long unsigned int)(s->dst.seqlo), (long unsigned int)(s->dst.seqhi - s->dst.seqlo));
printk(" %u:%u", s->src.state, s->dst.state);
}
void
print_flags(u_int8_t f)
{
if (f) printk(" ");
if (f & TH_FIN ) printk("F");
if (f & TH_SYN ) printk("S");
if (f & TH_RST ) printk("R");
if (f & TH_PUSH) printk("P");
if (f & TH_ACK ) printk("A");
if (f & TH_URG ) printk("U");
}
/* ------------------------------------------------------------------------ */
inline int
match_addr(u_int8_t n, u_int32_t a, u_int32_t m, u_int32_t b)
{
return n == !((a & m) == (b & m));
}
inline int
match_port(u_int8_t op, u_int16_t a1, u_int16_t a2, u_int16_t p)
{
switch (op) {
case 1: return (p >= a1) && (p <= a2);
case 2: return p == a1;
case 3: return p != a1;
case 4: return p < a1;
case 5: return p <= a1;
case 6: return p > a1;
case 7: return p >= a1;
}
return 0; /* never reached */
}
/* ------------------------------------------------------------------------ */
struct nat *
get_nat(const struct net_device *ifp, u_int8_t proto, u_int32_t addr)
{
struct nat *n = nathead, *nm = NULL;
while ((n != NULL) && (nm == NULL)) {
if ((n->ifp == ifp) &&
(!n->proto || (n->proto == proto)) &&
match_addr(n->not, n->saddr, n->smask, addr))
nm = n;
else
n = n->next;
}
return nm;
}
struct rdr *
get_rdr(const struct net_device *ifp, u_int8_t proto, u_int32_t addr, u_int16_t port)
{
struct rdr *r = rdrhead, *rm = NULL;
while ((r != NULL) && (rm == NULL)) {
if ((r->ifp == ifp) &&
(!r->proto || (r->proto == proto)) &&
match_addr(r->not, r->daddr, r->dmask, addr) &&
(r->dport == port))
rm = r;
else
r = r->next;
}
return rm;
}
/* ------------------------------------------------------------------- */
inline signed char
tree_key_compare(struct tree_key *a, struct tree_key *b)
{
/*
* could use memcmp(), but with the best manual order, we can
* minimize the number of average compares. what is faster?
*/
if (a->proto < b->proto ) return -1;
if (a->proto > b->proto ) return 1;
if (a->addr[0] < b->addr[0]) return -1;
if (a->addr[0] > b->addr[0]) return 1;
if (a->addr[1] < b->addr[1]) return -1;
if (a->addr[1] > b->addr[1]) return 1;
if (a->port[0] < b->port[0]) return -1;
if (a->port[0] > b->port[0]) return 1;
if (a->port[1] < b->port[1]) return -1;
if (a->port[1] > b->port[1]) return 1;
return 0;
}
inline void
tree_rotate_left(struct tree_node **p)
{
struct tree_node *q = *p;
*p = (*p)->right;
q->right = (*p)->left;
(*p)->left = q;
q->balance--;
if ((*p)->balance > 0)
q->balance -= (*p)->balance;
(*p)->balance--;
if (q->balance < 0)
(*p)->balance += q->balance;
}
inline void
tree_rotate_right(struct tree_node **p)
{
struct tree_node *q = *p;
*p = (*p)->left;
q->left = (*p)->right;
(*p)->right = q;
q->balance++;
if ((*p)->balance < 0)
q->balance -= (*p)->balance;
(*p)->balance++;
if (q->balance > 0)
(*p)->balance += q->balance;
}
int
tree_insert(struct tree_node **p, struct tree_key *key, struct state *state)
{
int deltaH = 0;
if (*p == NULL) {
*p = kmalloc(sizeof(struct tree_node), GFP_ATOMIC);
if (*p == NULL) {
ERR("packetfilter: malloc() failed\n");
return 0;
}
memcpy(&(*p)->key, key, sizeof(struct tree_key));
(*p)->state = state;
(*p)->balance = 0;
(*p)->left = (*p)->right = NULL;
deltaH = 1;
} else if (tree_key_compare(key, &(*p)->key) > 0) {
if (tree_insert(&(*p)->right, key, state)) {
(*p)->balance++;
if ((*p)->balance == 1)
deltaH = 1;
else if ((*p)->balance == 2) {
if ((*p)->right->balance == -1)
tree_rotate_right(&(*p)->right);
tree_rotate_left(p);
}
}
} else {
if (tree_insert(&(*p)->left, key, state)) {
(*p)->balance--;
if ((*p)->balance == -1)
deltaH = 1;
else if ((*p)->balance == -2) {
if ((*p)->left->balance == 1)
tree_rotate_left(&(*p)->left);
tree_rotate_right(p);
}
}
}
return deltaH;
}
int
tree_remove(struct tree_node **p, struct tree_key *key)
{
int deltaH = 0;
signed char c;
if (*p == NULL)
return 0;
c = tree_key_compare(key, &(*p)->key);
if (c < 0) {
if (tree_remove(&(*p)->left, key)) {
(*p)->balance++;
if ((*p)->balance == 0)
deltaH = 1;
else if ((*p)->balance == 2) {
if ((*p)->right->balance == -1)
tree_rotate_right(&(*p)->right);
tree_rotate_left(p);
if ((*p)->balance == 0)
deltaH = 1;
}
}
} else if (c > 0) {
if (tree_remove(&(*p)->right, key)) {
(*p)->balance--;
if ((*p)->balance == 0)
deltaH = 1;
else if ((*p)->balance == -2) {
if ((*p)->left->balance == 1)
tree_rotate_left(&(*p)->left);
tree_rotate_right(p);
if ((*p)->balance == 0)
deltaH = 1;
}
}
} else {
if ((*p)->right == NULL) {
struct tree_node *p0 = *p;
*p = (*p)->left;
kfree(p0);
deltaH = 1;
} else if ((*p)->left == NULL) {
struct tree_node *p0 = *p;
*p = (*p)->right;
kfree(p0);
deltaH = 1;
} else {
struct tree_node **qq = &(*p)->left;
while ((*qq)->right != NULL)
qq = &(*qq)->right;
memcpy(&(*p)->key, &(*qq)->key, sizeof(struct tree_key));
(*p)->state = (*qq)->state;
memcpy(&(*qq)->key, key, sizeof(struct tree_key));
if (tree_remove(&(*p)->left, key)) {
(*p)->balance++;
if ((*p)->balance == 0)
deltaH = 1;
else if ((*p)->balance == 2) {
if ((*p)->right->balance == -1)
tree_rotate_right(&(*p)->right);
tree_rotate_left(p);
if ((*p)->balance == 0)
deltaH = 1;
}
}
}
}
return deltaH;
}
inline struct state *
find_state(struct tree_node *p, struct tree_key *key)
{
signed char c;
while ((p != NULL) && (c = tree_key_compare(&p->key, key)))
p = (c > 0) ? p->left : p->right;
status.state_searches++;
return p ? p->state : NULL;
}
void
insert_state(struct state *state)
{
struct tree_key key;
key.proto = state->proto;
key.addr[0] = state->lan.addr;
key.port[0] = state->lan.port;
key.addr[1] = state->ext.addr;
key.port[1] = state->ext.port;
/* sanity checks can be removed later, should never occur */
if (find_state(tree_lan_ext, &key) != NULL)
printk("packetfilter: ERROR! insert invalid\n");
else {
tree_insert(&tree_lan_ext, &key, state);
if (find_state(tree_lan_ext, &key) != state)
ERR("packetfilter: ERROR! insert failed\n");
}
key.proto = state->proto;
key.addr[0] = state->ext.addr;
key.port[0] = state->ext.port;
key.addr[1] = state->gwy.addr;
key.port[1] = state->gwy.port;
if (find_state(tree_ext_gwy, &key) != NULL)
ERR("packetfilter: ERROR! insert invalid\n");
else {
tree_insert(&tree_ext_gwy, &key, state);
if (find_state(tree_ext_gwy, &key) != state)
ERR("packetfilter: ERROR! insert failed\n");
}
state->next = statehead;
statehead = state;
status.state_inserts++;
status.states++;
}
void
purge_expired_states(void)
{
struct tree_key key;
struct state *cur = statehead, *prev = NULL;
while (cur != NULL) {
if (cur->expire <= tv.tv_sec) {
key.proto = cur->proto;
key.addr[0] = cur->lan.addr;
key.port[0] = cur->lan.port;
key.addr[1] = cur->ext.addr;
key.port[1] = cur->ext.port;
/* sanity checks can be removed later */
if (find_state(tree_lan_ext, &key) != cur)
ERR("packetfilter: ERROR! remove invalid\n");
tree_remove(&tree_lan_ext, &key);
if (find_state(tree_lan_ext, &key) != NULL)
ERR("packetfilter: ERROR! remove failed\n");
key.proto = cur->proto;
key.addr[0] = cur->ext.addr;
key.port[0] = cur->ext.port;
key.addr[1] = cur->gwy.addr;
key.port[1] = cur->gwy.port;
if (find_state(tree_ext_gwy, &key) != cur)
ERR("packetfilter: ERROR! remove invalid\n");
tree_remove(&tree_ext_gwy, &key);
if (find_state(tree_ext_gwy, &key) != NULL)
ERR("packetfilter: ERROR! remove failed\n");
//(prev ? prev->next : statehead) = cur->next;
if(prev)
prev->next = cur->next;
else
statehead = cur->next;
kfree(cur);
cur = (prev ? prev->next : statehead);
status.state_removals++;
status.states--;
} else {
prev = cur;
cur = cur->next;
}
}
}
/* ------------------------------------------------------------------------ */
inline u_short
fix(u_short cksum, u_short old, u_short new)
{
u_long l = cksum + old - new;
l = (l >> 16) + (l & 65535);
l = l & 65535;
return l ? l : 65535;
}
void
change_ap(u_int32_t *a, u_int16_t *p, u_int16_t *ic, u_int16_t *pc, u_int32_t an,
u_int16_t pn)
{
u_int32_t ao = *a;
u_int16_t po = *p;
*a = an;
*ic = fix(fix(*ic, ao / 65536, an / 65536), ao % 65536, an % 65536);
*p = pn;
*pc = fix(fix(fix(*pc, ao / 65536, an / 65536), ao % 65536, an % 65536),
po, pn);
}
void
change_a(u_int32_t *a, u_int16_t *c, u_int32_t an)
{
u_int32_t ao = *a;
*a = an;
*c = fix(fix(*c, ao / 65536, an / 65536), ao % 65536, an % 65536);
}
void
change_icmp(u_int32_t *ia, u_int16_t *ip, u_int32_t *oa, u_int32_t na,
u_int16_t np, u_int16_t *pc, u_int16_t *h2c, u_int16_t *ic, u_int16_t *hc)
{
u_int32_t oia = *ia, ooa = *oa, opc = *pc, oh2c = *h2c;
u_int16_t oip = *ip;
// change inner protocol port, fix inner protocol checksum
*ip = np;
*pc = fix(*pc, oip, *ip);
*ic = fix(*ic, oip, *ip);
*ic = fix(*ic, opc, *pc);
// change inner ip address, fix inner ip checksum and icmp checksum
*ia = na;
*h2c = fix(fix(*h2c, oia / 65536, *ia / 65536), oia % 65536, *ia % 65536);
*ic = fix(fix(*ic, oia / 65536, *ia / 65536), oia % 65536, *ia % 65536);
*ic = fix(*ic, oh2c, *h2c);
// change outer ip address, fix outer ip checksum
*oa = na;
*hc = fix(fix(*hc, ooa / 65536, *oa / 65536), ooa % 65536, *oa % 65536);
}
void
send_reset(int direction, const struct net_device *ifp, struct iphdr *h, struct tcphdr *th)
{
/*
struct mbuf *m;
int len = sizeof(struct iphdr) + sizeof(struct tcphdr);
struct ip *h2;
struct tcphdr *th2;
*/
ERR("send_reset not implemented!!\n");
}
/* ----------------------------------------------------------------------------- */
/*
* Watch out!!!! h->tot_len is at this stage in network order in Linux but not OpenBSD!
* So, use ntohs everywhere for h->tot_len. This took me a while to figure out :-)
*
*/
struct state *
pf_test_state_tcp(int direction, const struct net_device *ifp, struct iphdr *h, struct tcphdr *th)
{
struct state *s;
struct tree_key key;
key.proto = IPPROTO_TCP;
key.addr[0] = h->saddr;
key.port[0] = th->source;
key.addr[1] = h->daddr;
key.port[1] = th->dest;
s = find_state((direction == PF_IN) ? tree_ext_gwy : tree_lan_ext, &key);
if (s != NULL) {
u_int16_t len = ntohs(h->tot_len) - ((h->ihl + th->doff) << 2);
u_int32_t seq = ntohl(th->seq), ack = ntohl(th->ack_seq);
struct peer *src, *dst;
if (direction == s->direction) {
src = &s->src;
dst = &s->dst;
} else {
src = &s->dst;
dst = &s->src;
}
/* some senders do that instead of ACKing FIN */
if ((th->rst) && !ack && !len &&
((seq == src->seqhi) || (seq == src->seqhi-1)) &&
(src->state >= 4) && (dst->state >= 3))
ack = dst->seqhi;
if ((dst->seqhi >= dst->seqlo ?
(ack >= dst->seqlo) && (ack <= dst->seqhi) :
(ack >= dst->seqlo) || (ack <= dst->seqhi)) ||
(seq == src->seqlo) || (seq == src->seqlo-1)) {
s->packets++;
s->bytes += len;
/* update sequence number range */
if (th->ack)
dst->seqlo = ack;
if (th->syn || th->fin)
len++;
if (th->syn) {
src->seqhi = seq + len;
src->seqlo = src->seqhi - 1;
} else if ((seq + len) - src->seqhi < 65536)
src->seqhi = seq + len;
/* update states */
if (th->syn)
if (src->state < 1)
src->state = 1;
if (th->fin)
if (src->state < 3)
src->state = 3;
if ((th->ack) && (ack == dst->seqhi)) {
if (dst->state == 1)
dst->state = 2;
else if (dst->state == 3)
dst->state = 4;
}
if (th->rst)
src->state = dst->state = 5;
/* update expire time */
if ((src->state >= 4) && (dst->state >= 4))
s->expire = tv.tv_sec + 5;
else if ((src->state >= 3) || (dst->state >= 3))
s->expire = tv.tv_sec + 300;
else if ((src->state < 2) || (dst->state < 2))
s->expire = tv.tv_sec + 30;
else
s->expire = tv.tv_sec + 24*60*60;
/* translate source/destination address, if necessary */
if ((s->lan.addr != s->gwy.addr)
|| (s->lan.port != s->gwy.port)) {
if (direction == PF_OUT)
change_ap(&h->saddr, &th->source,
&h->check, &th->check,
s->gwy.addr, s->gwy.port);
else
change_ap(&h->daddr, &th->dest,
&h->check, &th->check,
s->lan.addr, s->lan.port);
}
} else {
struct tcphdrbsd *th2 = (struct tcphdrbsd*)th;
printk("packetfilter: BAD state: ");
print_state(direction, s);
print_flags(th2->th_flags);
printk(" seq=%lu ack=%lu len=%u ", (long unsigned int)seq, (long unsigned int)ack, len);
printk("\n");
s = NULL;
}
return s;
}
return NULL;
}
int
pf_test_tcp(int direction, const struct net_device *ifp, struct iphdr *h, struct tcphdr *th)
{
struct nat *nat = NULL;
struct rdr *rdr = NULL;
u_int32_t baddr = 0;
u_int16_t bport = 0;
struct rule *r = rulehead, *rm = NULL;
u_int16_t nr = 1, mnr = 0;
struct tcphdrbsd *th2 = (struct tcphdrbsd *)th;
if (direction == PF_OUT) {
/* check outgoing packet for NAT */
if ((nat = get_nat(ifp, IPPROTO_TCP, h->saddr)) != NULL) {
baddr = h->saddr;
bport = th->source;
change_ap(&h->saddr, &th->source, &h->check,
&th->check, nat->daddr, htons(next_port_tcp));
}
} else {
/* check incoming packet for RDR */
if ((rdr = get_rdr(ifp, IPPROTO_TCP, h->daddr,
th->dest)) != NULL) {
baddr = h->daddr;
bport = th->dest;
change_ap(&h->daddr, &th->dest,
&h->check, &th->check, rdr->raddr, rdr->rport);