*skb);
if (ret != NF_ACCEPT) return ret;
}
/* Finally, check the TCP port rule */
if (deny_port && DENY_PORT_ACTIVE) {
ret = check_tcp_packet(*skb);
if (ret != NF_ACCEPT) return ret;
}
return NF_ACCEPT; /* We are happy to keep the packet */
}
/* Function to copy the LWFW statistics to a userspace buffer */
static int copy_stats(struct lwfw_stats *statbuff)
{
NULL_CHECK(statbuff);
copy_to_user(statbuff, &lwfw_statistics,
sizeof(struct lwfw_stats));
return 0;
}
/* Function that compares a received TCP packet''''s destination port
* with the port specified in the Port Deny Rule. If a processing
* error occurs, NF_ACCEPT will be returned so that the packet is
* not lost. */
static int check_tcp_packet(struct sk_buff *skb)
{
/* Seperately defined pointers to header structures are used
* to access the TCP fields because it seems that the so-called
* transport header from skb is the same as its network header TCP packets.
* If you don''''t believe me then print the addresses of skb->nh.iph
* and skb->h.th.
* It would have been nicer if the network header only was IP and
* the transport header was TCP but what can you do? */
struct tcphdr *thead;
/* We don''''t want any NULL pointers in the chain to the TCP header. */
if (!skb ) return NF_ACCEPT;
if (!(skb->nh.iph)) return NF_ACCEPT;
/* Be sure this is a TCP packet first */
if (skb->nh.iph->protocol != IPPROTO_TCP) {
return NF_ACCEPT;
}
thead = (struct tcphdr *)(skb->data + (skb->nh.iph->ihl * 4));
/* Now check the destination port */
if ((thead->dest) == deny_port) {
/* Update statistics */
lwfw_statistics.total_dropped++;
lwfw_statistics.tcp_dropped++;
return NF_DROP;
}
return NF_ACCEPT;
}
/* Function that compares a received IPv4 packet''''s source address
* with the address specified in the IP Deny Rule. If a processing
* error occurs, NF_ACCEPT will be returned so that the packet is
* not lost. */
static int check_ip_packet(struct sk_buff *skb)
{
/* We don''''t want any NULL pointers in the chain to the IP header. */
if (!skb ) return NF_ACCEPT;
if (!(skb->nh.iph)) return NF_ACCEPT;
if (skb->nh.iph->saddr == deny_ip) {/* Matches the address. Barf. */
lwfw_statistics.ip_dropped++; /* Update the statistics */
lwfw_statistics.total_dropped++;
return NF_DROP;
}
return NF_ACCEPT;
}
static int set_if_rule(char *name)
{
int ret = 0;
char *if_dup; /* Duplicate interface */
/* Make sure the name is non-null */
NULL_CHECK(name);
/* Free any previously saved interface name */
if (deny_if) {
kfree(deny_if);
deny_if = NULL;
}
if ((if_dup = kmalloc(strlen((char *)name) + 1, GFP_KERNEL))
== NULL) {
ret = -ENOMEM;
} else {
memset(if_dup, 0x00, strlen((char *)name) + 1);
memcpy(if_dup, (char *)name, strlen((char *)name));
}
deny_if = if_dup;
lwfw_statistics.if_dropped = 0; /* Reset drop count for IF rule */
printk("LWFW: Set to deny from interface: %s\n", deny_if);
return ret;
}
static int set_ip_rule(unsigned int ip)
{
deny_ip = ip;
lwfw_statistics.ip_dropped = 0; /* Reset drop count for IP rule */
printk("LWFW: Set to deny from IP address: %d.%d.%d.%d\n",
ip & 0x000000FF, (ip & 0x0000FF00) >> 8,
(ip & 0x00FF0000) >> 16, (ip & 0xFF000000) >> 24);
return 0;
}
static int set_port_rule(unsigned short port)
{
deny_port = port;
lwfw_statistics.tcp_dropped = 0; /* Reset drop count for TCP rule */
printk("LWFW: Set to deny for TCP port: %d\n",
((port & 0xFF00) >> 8 | (port & 0x00FF) << 8));
return 0;
}
/*********************************************/
/*
* File operations functions for control device
*/
static int lwfw_ioctl(struct inode *inode, struct file *file,
unsigned int cmd, unsigned long arg)
{
int ret = 0;
switch (cmd) {
case LWFW_GET_VERS:
return LWFW_VERS;
case LWFW_ACTIVATE: {
active = 1;
printk("LWFW: Activated.\n");
if (!deny_if && !deny_ip && !deny_port) {
printk("LWFW: No deny options set.\n");
}
break;
}
case LWFW_DEACTIVATE: {
active ^= active;
printk("LWFW: Deactivated.\n");
break;
}
case LWFW_GET_STATS: {
ret = copy_stats((struct lwfw_stats *)arg);
break;
}
case LWFW_DENY_IF: {
ret = set_if_rule((char *)arg);
break;
}
case LWFW_DENY_IP: {
ret = set_ip_rule((unsigned int)arg);
break;
}
case LWFW_DENY_PORT: {
ret = set_port_rule((unsigned short)arg);
break;
}
default:
ret = -EBADRQC;
};
return ret;
}
/* Called whenever open() is called on the device file */
static int lwfw_open(struct inode *inode, struct file *file)
{
if (lwfw_ctrl_in_use) {
return -EBUSY;
} else {
MOD_INC_USE_COUNT;
lwfw_ctrl_in_use++;
return 0;
}
return 0;
}
/* Called whenever close() is called on the device file */
static int lwfw_release(struct inode *inode, struct file *file)
{
lwfw_ctrl_in_use ^= lwfw_ctrl_in_use;
MOD_DEC_USE_COUNT;
return 0;
}
/*********************************************/
/*
* Module initialisation and cleanup follow...
*/
int init_module()
{
/* Register the control device, /dev/lwfw */
SET_MODULE_OWNER(&lwfw_fops);
/* Attempt to register the LWFW control device */
if ((major = register_chrdev(LWFW_MAJOR, LWFW_NAME,
&lwfw_fops)) < 0) {
printk("LWFW: Failed registering control device!\n");
printk("LWFW: Module installation aborted.\n");
return major;
}
/* Make sure the usage marker for the control device is cleared */
lwfw_ctrl_in_use ^= lwfw_ctrl_in_use;
printk("\nLWFW: Control device successfully registered.\n");
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