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