/*
* INET An implementation of the TCP/IP protocol suite for the LINUX
* operating system. INET is implemented using the BSD Socket
* interface as the means of communication with the user level.
*
* Generic frame diversion
*
* Authors:
* Benoit LOCHER: initial integration within the kernel with support for ethernet
* Dave Miller: improvement on the code (correctness, performance and source files)
*
*/
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/inet.h>
#include <linux/ip.h>
#include <linux/udp.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/skbuff.h>
#include <linux/capability.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <net/dst.h>
#include <net/arp.h>
#include <net/sock.h>
#include <net/ipv6.h>
#include <net/ip.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#include <asm/checksum.h>
#include <linux/divert.h>
#include <linux/sockios.h>
const char sysctl_divert_version[32]="0.46"; /* Current version */
static int __init dv_init(void)
{
return 0;
}
module_init(dv_init);
/*
* Allocate a divert_blk for a device. This must be an ethernet nic.
*/
int alloc_divert_blk(struct net_device *dev)
{
int alloc_size = (sizeof(struct divert_blk) + 3) & ~3;
dev->divert = NULL;
if (dev->type == ARPHRD_ETHER) {
dev->divert = (struct divert_blk *)
kmalloc(alloc_size, GFP_KERNEL);
if (dev->divert == NULL) {
printk(KERN_INFO "divert: unable to allocate divert_blk for %s\n",
dev->name);
return -ENOMEM;
}
memset(dev->divert, 0, sizeof(struct divert_blk));
dev_hold(dev);
}
return 0;
}
/*
* Free a divert_blk allocated by the above function, if it was
* allocated on that device.
*/
void free_divert_blk(struct net_device *dev)
{
if (dev->divert) {
kfree(dev->divert);
dev->divert=NULL;
dev_put(dev);
}
}
/*
* Adds a tcp/udp (source or dest) port to an array
*/
static int add_port(u16 ports[], u16 port)
{
int i;
if (port == 0)
return -EINVAL;
/* Storing directly in network format for performance,
* thanks Dave :)
*/
port = htons(port);
for (i = 0; i < MAX_DIVERT_PORTS; i++) {
if (ports[i] == port)
return -EALREADY;
}
for (i = 0; i < MAX_DIVERT_PORTS; i++) {
if (ports[i] == 0) {
ports[i] = port;
return 0;
}
}
return -ENOBUFS;
}
/*
* Removes a port from an array tcp/udp (source or dest)
*/
static int remove_port(u16 ports[], u16 port)
{
int i;
if (port == 0)
return -EINVAL;
/* Storing directly in network format for performance,
* thanks Dave !
*/
port = htons(port);
for (i = 0; i < MAX_DIVERT_PORTS; i++) {
if (ports[i] == port) {
ports[i] = 0;
return 0;
}
}
return -EINVAL;
}
/* Some basic sanity checks on the arguments passed to divert_ioctl() */
static int check_args(struct divert_cf *div_cf, struct net_device **dev)
{
char devname[32];
int ret;
if (dev == NULL)
return -EFAULT;
/* GETVERSION: all other args are unused */
if (div_cf->cmd == DIVCMD_GETVERSION)
return 0;
/* Network device index should reasonably be between 0 and 1000 :) */
if (div_cf->dev_index < 0 || div_cf->dev_index > 1000)
return -EINVAL;
/* Let's try to find the ifname */
sprintf(devname, "eth%d", div_cf->dev_index);
*dev = dev_get_by_name(devname);
/* dev should NOT be null */
if (*dev == NULL)
return -EINVAL;
ret = 0;
/* user issuing the ioctl must be a super one :) */
if (!capable(CAP_SYS_ADMIN)) {
ret = -EPERM;
goto out;
}
/* Device must have a divert_blk member NOT null */
if ((*dev)->divert == NULL)
ret = -EINVAL;
out:
dev_put(*dev);
return ret;
}
/*
* control function of the diverter
*/
#if 0
#define DVDBG(a) \
printk(KERN_DEBUG "divert_ioctl() line %d %s\n", __LINE__, (a))
#else
#define DVDBG(a)
#endif
int divert_ioctl(unsigned int cmd, struct divert_cf __user *arg)
{
struct divert_cf div_cf;
struct divert_blk *div_blk;
struct net_device *dev;
int ret;
switch (cmd) {
case SIOCGIFDIVERT:
DVDBG("SIOCGIFDIVERT, copy_from_user");
if (copy_from_user(&div_cf, arg, sizeof(struct divert_cf)))
return -EFAULT;
DVDBG("before check_args");
ret = check_args(&div_cf, &dev);
if (ret)
return ret;
DVDBG("after checkargs");
div_blk = dev->divert;
DVDBG("befre switch()");
switch (div_cf.cmd) {
case DIVCMD_GETSTATUS:
/* Now, just give the user the raw divert block
* for him to play with :)
*/
if (copy_to_user(div_cf.arg1.ptr, dev->divert,
sizeof(struct divert_blk)))
return -EFAULT;
break;
case DIVCMD_GETVERSION:
DVDBG("GETVERSION: checking ptr");
if (div_cf.arg1.ptr == NULL)
return -EINVAL;
DVDBG("GETVERSION: copying data to userland");
if (copy_to_user(div_cf.arg1.ptr,
sysctl_divert_version, 32))
return -EFAULT;
DVDBG("GETVERSION: data copied");
break;
default:
return -EINVAL;
}
break;
case SIOCSIFDIVERT:
if (copy_from_user(&div_cf, arg, sizeof(struct divert_cf)))
return -EFAULT;
ret = check_args(&div_cf, &dev);
if (ret)
return ret;
div_blk = dev->divert;
switch(div_cf.cmd) {
case DIVCMD_RESET:
div_blk->divert = 0;
div_blk->protos = DIVERT_PROTO_NONE;
memset(div_blk->tcp_dst, 0,
MAX_DIVERT_PORTS * sizeof(u16));
memset(div_blk->tcp_src, 0,
MAX_DIVERT_PORTS * sizeof(u16));
memset(div_blk->udp_dst, 0,
MAX_DIVERT_PORTS * sizeof(u16));
memset(div_blk->udp_src, 0,
MAX_DIVERT_PORTS * sizeof(u16));
return 0;
case DIVCMD_DIVERT:
switch(div_cf.arg1.int32) {
case DIVARG1_ENABLE:
if (div_blk->divert)
return -EALREADY;
div_blk->divert = 1;
break;
case DIVARG1_DISABLE:
if (!div_blk->divert)
return -EALREADY;
div_blk->divert = 0;
break;
default:
return -EINVAL;
}
break;
case DIVCMD_IP:
switch(div_cf.arg1.int32) {
case DIVARG1_ENABLE:
if (div_blk->protos & DIVERT_PROTO_IP)
return -EALREADY;
div_blk->protos |= DIVERT_PROTO_IP;
break;
case DIVARG1_DISABLE:
if (!(div_blk->protos & DIVERT_PROTO_IP))
return -EALREADY;
div_blk->protos &= ~DIVERT_PROTO_IP;
break;
default:
return -EINVAL;
}
break;
case DIVCMD_TCP:
switch(div_cf.arg1.int32) {
case DIVARG1_ENABLE:
if (div_blk->protos & DIVERT_PROTO_TCP)
return -EALREADY;
div_blk->protos |= DIVERT_PROTO_TCP;
break;
case DIVARG1_DISABLE:
if (!(div_blk->protos & DIVERT_PROTO_TCP))
return -EALREADY;
div_blk->protos &= ~DIVERT_PROTO_TCP;
break;
default:
return -EINVAL;
}
break;
case DIVCMD_TCPDST:
switch(div_cf.arg1.int32) {
case DIVARG1_ADD:
return add_port(div_blk->tcp_dst,
div_cf.arg2.uint16);
case DIVARG1_REMOVE:
return remove_port(div_blk->tcp_dst,
div_cf.arg2.uint16);
default:
return -EINVAL;
}
break;
case DIVCMD_TCPSRC:
switch(div_cf.arg1.int32) {
case DIVARG1_ADD:
return add_port(div_blk->tcp_src,
div_cf.arg2.uint16);
case DIVARG1_REMOVE:
return remove_port(div_blk->tcp_src,
div_cf.arg2.uint16);
default:
return -EINVAL;
}
break;
case DIVCMD_UDP:
switch(div_cf.arg1.int32) {
case DIVARG1_ENABLE:
if (div_blk->protos & DIVERT_PROTO_UDP)
return -EALREADY;
div_blk->protos |= DIVERT_PROTO_UDP;
break;
case DIVARG1_DISABLE:
if (!(div_blk->protos & DIVERT_PROTO_UDP))
return -EALREADY;
div_blk->protos &= ~DIVERT_PROTO_UDP;
break;
default:
return -EINVAL;
}
break;
case DIVCMD_UDPDST:
switch(div_cf.arg1.int32) {
case DIVARG1_ADD:
return add_port(div_blk->udp_dst,
div_cf.arg2.uint16);
case DIVARG1_REMOVE:
return remove_port(div_blk->udp_dst,
div_cf.arg2.uint16);
default:
return -EINVAL;
}
break;
case DIVCMD_UDPSRC:
switch(div_cf.arg1.int32) {
case DIVARG1_ADD:
return add_port(div_blk->udp_src,
div_cf.arg2.uint16);
case DIVARG1_REMOVE:
return remove_port(div_blk->udp_src,
div_cf.arg2.uint16);
default:
return -EINVAL;
}
break;
case DIVCMD_ICMP:
switch(div_cf.arg1.int32) {
case DIVARG1_ENABLE:
if (div_blk->protos & DIVERT_PROTO_ICMP)
return -EALREADY;
div_blk->protos |= DIVERT_PROTO_ICMP;
break;
case DIVARG1_DISABLE:
if (!(div_blk->protos & DIVERT_PROTO_ICMP))
return -EALREADY;
div_blk->protos &= ~DIVERT_PROTO_ICMP;
break;
default:
return -EINVAL;
}
break;
default:
return -EINVAL;
}
break;
default:
return -EINVAL;
}
return 0;
}
/*
* Check if packet should have its dest mac address set to the box itself
* for diversion
*/
#define ETH_DIVERT_FRAME(skb) \
memcpy(eth_hdr(skb), skb->dev->dev_addr, ETH_ALEN); \
skb->pkt_type=PACKET_HOST
void divert_frame(struct sk_buff *skb)
{
struct ethhdr *eth = eth_hdr(skb);
struct iphdr *iph;
struct tcphdr *tcph;
struct udphdr *udph;
struct divert_blk *divert = skb->dev->divert;
int i, src, dst;
unsigned char *skb_data_end = skb->data + skb->len;
/* Packet is already aimed at us, return */
if (!compare_ether_addr(eth->h_dest, skb->dev->dev_addr))
return;
/* proto is not IP, do nothing */
if (eth->h_proto != htons(ETH_P_IP))
return;
/* Divert all IP frames ? */
if (divert->protos & DIVERT_PROTO_IP) {
ETH_DIVERT_FRAME(skb);
return;
}
/* Check for possible (maliciously) malformed IP frame (thanks Dave) */
iph = (struct iphdr *) skb->data;
if (((iph->ihl<<2)+(unsigned char*)(iph)) >= skb_data_end) {
printk(KERN_INFO "divert: malformed IP packet !\n");
return;
}
switch (iph->protocol) {
/* Divert all ICMP frames ? */
case IPPROTO_ICMP:
if (divert->protos & DIVERT_PROTO_ICMP) {
ETH_DIVERT_FRAME(skb);
return;
}
break;
/* Divert all TCP frames ? */
case IPPROTO_TCP:
if (divert->protos & DIVERT_PROTO_TCP) {
ETH_DIVERT_FRAME(skb);
return;
}
/* Check for possible (maliciously) malformed IP
* frame (thanx Dave)
*/
tcph = (struct tcphdr *)
(((unsigned char *)iph) + (iph->ihl<<2));
if (((unsigned char *)(tcph+1)) >= skb_data_end) {
printk(KERN_INFO "divert: malformed TCP packet !\n");
return;
}
/* Divert some tcp dst/src ports only ?*/
for (i = 0; i < MAX_DIVERT_PORTS; i++) {
dst = divert->tcp_dst[i];
src = divert->tcp_src[i];
if ((dst && dst == tcph->dest) ||
(src && src == tcph->source)) {
ETH_DIVERT_FRAME(skb);
return;
}
}
break;
/* Divert all UDP frames ? */
case IPPROTO_UDP:
if (divert->protos & DIVERT_PROTO_UDP) {
ETH_DIVERT_FRAME(skb);
return;
}
/* Check for possible (maliciously) malformed IP
* packet (thanks Dave)
*/
udph = (struct udphdr *)
(((unsigned char *)iph) + (iph->ihl<<2));
if (((unsigned char *)(udph+1)) >= skb_data_end) {
printk(KERN_INFO
"divert: malformed UDP packet !\n");
return;
}
/* Divert some udp dst/src ports only ? */
for (i = 0; i < MAX_DIVERT_PORTS; i++) {
dst = divert->udp_dst[i];
src = divert->udp_src[i];
if ((dst && dst == udph->dest) ||
(src && src == udph->source)) {
ETH_DIVERT_FRAME(skb);
return;
}
}
break;
}
}
