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Commit 5793f4be authored by Ralf Baechle's avatar Ralf Baechle Committed by Jeff Garzik
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[PATCH] SMACK support for mkiss 



SMACK (Stuttgart Modified Amateurradio CRC KISS) is a KISS variant that
uses CRC16 checksums to secure data transfers between the modem and host.
It's also used to communicate over a pty to applications such as Wampes.

Patches for Linux 2.4 by Thomas Osterried DL9SAU, upgraded to the latest
mkiss 2.6 mkiss driver by me.

Signed-off-by: default avatarThomas Osterried DL9SAU <thomas@x-berg.in-berlin.de>
Signed-off-by: default avatarRalf Baechle DL5RB <ralf@linux-mips.org>
Signed-off-by: default avatarJeff Garzik <jgarzik@pobox.com>
parent bc0a7438

drivers/net/hamradio/Kconfig

+1 −0
Original line number Diff line number Diff line 
config MKISS

	tristate "Serial port KISS driver"

	depends on AX25

	select CRC16

	---help---

	  KISS is a protocol used for the exchange of data between a computer

	  and a Terminal Node Controller (a small embedded system commonly

drivers/net/hamradio/mkiss.c

+147 −31
Original line number Diff line number Diff line
@@ -14,13 +14,14 @@ 
 *

 * Copyright (C) Hans Alblas PE1AYX <hans@esrac.ele.tue.nl>

 * Copyright (C) 2004, 05 Ralf Baechle DL5RB <ralf@linux-mips.org>

 * Copyright (C) 2004, 05 Thomas Osterried DL9SAU <thomas@x-berg.in-berlin.de>

 */



#include <linux/config.h>

#include <linux/module.h>

#include <asm/system.h>

#include <linux/bitops.h>

#include <asm/uaccess.h>

#include <linux/crc16.h>

#include <linux/string.h>

#include <linux/mm.h>

#include <linux/interrupt.h>
@@ -39,11 +40,6 @@ 


#include <net/ax25.h>



#ifdef CONFIG_INET

#include <linux/ip.h>

#include <linux/tcp.h>

#endif



#define AX_MTU		236



/* SLIP/KISS protocol characters. */
@@ -80,9 +76,13 @@ struct mkiss { 


	int		mode;

        int		crcmode;	/* MW: for FlexNet, SMACK etc.  */

	int		crcauto;	/* CRC auto mode */



#define CRC_MODE_NONE		0

#define CRC_MODE_FLEX		1

#define CRC_MODE_SMACK		2

#define CRC_MODE_FLEX_TEST	3

#define CRC_MODE_SMACK_TEST	4



	atomic_t		refcnt;

	struct semaphore	dead_sem;
@@ -151,6 +151,21 @@ static int check_crc_flex(unsigned char *cp, int size) 
	return 0;

}



static int check_crc_16(unsigned char *cp, int size)

{

	unsigned short crc = 0x0000;



	if (size < 3)

		return -1;



	crc = crc16(0, cp, size);



	if (crc != 0x0000)

		return -1;



	return 0;

}



/*

 * Standard encapsulation

 */
@@ -237,17 +252,40 @@ static void ax_bump(struct mkiss *ax) 


	spin_lock_bh(&ax->buflock);

	if (ax->rbuff[0] > 0x0f) {

		if (ax->rbuff[0] & 0x20) {

		        ax->crcmode = CRC_MODE_FLEX;

		if (ax->rbuff[0] & 0x80) {

			if (check_crc_16(ax->rbuff, ax->rcount) < 0) {

				ax->stats.rx_errors++;

				spin_unlock_bh(&ax->buflock);



				return;

			}

			if (ax->crcmode != CRC_MODE_SMACK && ax->crcauto) {

				printk(KERN_INFO

				       "mkiss: %s: Switchting to crc-smack\n",

				       ax->dev->name);

				ax->crcmode = CRC_MODE_SMACK;

			}

			ax->rcount -= 2;

			*ax->rbuff &= ~0x80;

		} else if (ax->rbuff[0] & 0x20)  {

			if (check_crc_flex(ax->rbuff, ax->rcount) < 0) {

				ax->stats.rx_errors++;

				spin_unlock_bh(&ax->buflock);

				return;

			}

			if (ax->crcmode != CRC_MODE_FLEX && ax->crcauto) {

				printk(KERN_INFO

				       "mkiss: %s: Switchting to crc-flexnet\n",

				       ax->dev->name);

				ax->crcmode = CRC_MODE_FLEX;

			}

			ax->rcount -= 2;

                        /* dl9sau bugfix: the trailling two bytes flexnet crc

                         * will not be passed to the kernel. thus we have

                         * to correct the kissparm signature, because it

                         * indicates a crc but there's none



			/*

			 * dl9sau bugfix: the trailling two bytes flexnet crc

			 * will not be passed to the kernel. thus we have to

			 * correct the kissparm signature, because it indicates

			 * a crc but there's none

			 */

			*ax->rbuff &= ~0x20;

		}
@@ -417,9 +455,58 @@ static void ax_encaps(struct net_device *dev, unsigned char *icp, int len) 
	p = icp;



	spin_lock_bh(&ax->buflock);

        switch (ax->crcmode) {

	         unsigned short crc;

	if ((*p & 0x0f) != 0) {

		/* Configuration Command (kissparms(1).

		 * Protocol spec says: never append CRC.

		 * This fixes a very old bug in the linux

		 * kiss driver. -- dl9sau */

		switch (*p & 0xff) {

		case 0x85:

			/* command from userspace especially for us,

			 * not for delivery to the tnc */

			if (len > 1) {

				int cmd = (p[1] & 0xff);

				switch(cmd) {

				case 3:

				  ax->crcmode = CRC_MODE_SMACK;

				  break;

				case 2:

				  ax->crcmode = CRC_MODE_FLEX;

				  break;

				case 1:

				  ax->crcmode = CRC_MODE_NONE;

				  break;

				case 0:

				default:

				  ax->crcmode = CRC_MODE_SMACK_TEST;

				  cmd = 0;

				}

				ax->crcauto = (cmd ? 0 : 1);

				printk(KERN_INFO "mkiss: %s: crc mode %s %d\n", ax->dev->name, (len) ? "set to" : "is", cmd);

			}

			spin_unlock_bh(&ax->buflock);

			netif_start_queue(dev);



			return;

		default:

			count = kiss_esc(p, (unsigned char *)ax->xbuff, len);

		}

	} else {

		unsigned short crc;

		switch (ax->crcmode) {

		case CRC_MODE_SMACK_TEST:

			ax->crcmode  = CRC_MODE_FLEX_TEST;

			printk(KERN_INFO "mkiss: %s: Trying crc-smack\n", ax->dev->name);

			// fall through

		case CRC_MODE_SMACK:

			*p |= 0x80;

			crc = swab16(crc16(0, p, len));

			count = kiss_esc_crc(p, (unsigned char *)ax->xbuff, crc, len+2);

			break;

		case CRC_MODE_FLEX_TEST:

			ax->crcmode = CRC_MODE_NONE;

			printk(KERN_INFO "mkiss: %s: Trying crc-flexnet\n", ax->dev->name);

			// fall through

		case CRC_MODE_FLEX:

			*p |= 0x20;

			crc = calc_crc_flex(p, len);
@@ -428,7 +515,7 @@ static void ax_encaps(struct net_device *dev, unsigned char *icp, int len) 


		default:

			count = kiss_esc(p, (unsigned char *)ax->xbuff, len);

		 break;

		}

  	}



	set_bit(TTY_DO_WRITE_WAKEUP, &ax->tty->flags);
@@ -439,8 +526,6 @@ static void ax_encaps(struct net_device *dev, unsigned char *icp, int len) 
	ax->dev->trans_start = jiffies;

	ax->xleft = count - actual;

	ax->xhead = ax->xbuff + actual;



	spin_unlock_bh(&ax->buflock);

}



/* Encapsulate an AX.25 packet and kick it into a TTY queue. */
@@ -643,6 +728,8 @@ static void mkiss_put(struct mkiss *ax) 
		up(&ax->dead_sem);

}



static int crc_force = 0;	/* Can be overridden with insmod */



static int mkiss_open(struct tty_struct *tty)

{

	struct net_device *dev;
@@ -682,6 +769,33 @@ static int mkiss_open(struct tty_struct *tty) 
	if (register_netdev(dev))

		goto out_free_buffers;



	/* after register_netdev() - because else printk smashes the kernel */

	switch (crc_force) {

	case 3:

		ax->crcmode  = CRC_MODE_SMACK;

		printk(KERN_INFO "mkiss: %s: crc mode smack forced.\n",

		       ax->dev->name);

		break;

	case 2:

		ax->crcmode  = CRC_MODE_FLEX;

		printk(KERN_INFO "mkiss: %s: crc mode flexnet forced.\n",

		       ax->dev->name);

		break;

	case 1:

		ax->crcmode  = CRC_MODE_NONE;

		printk(KERN_INFO "mkiss: %s: crc mode disabled.\n",

		       ax->dev->name);

		break;

	case 0:

		/* fall through */

	default:

		crc_force = 0;

		printk(KERN_INFO "mkiss: %s: crc mode is auto.\n",

		       ax->dev->name);

		ax->crcmode  = CRC_MODE_SMACK_TEST;

	}

	ax->crcauto = (crc_force ? 0 : 1);



	netif_start_queue(dev);



	/* Done.  We have linked the TTY line to a channel. */
@@ -903,6 +1017,8 @@ static void __exit mkiss_exit_driver(void) 


MODULE_AUTHOR("Ralf Baechle DL5RB <ralf@linux-mips.org>");

MODULE_DESCRIPTION("KISS driver for AX.25 over TTYs");

MODULE_PARM(crc_force, "i");

MODULE_PARM_DESC(crc_force, "crc [0 = auto | 1 = none | 2 = flexnet | 3 = smack]");

MODULE_LICENSE("GPL");

MODULE_ALIAS_LDISC(N_AX25);