From 5793f4be23f0171b4999ca68a39a9157b44139f3 Mon Sep 17 00:00:00 2001 From: Ralf Baechle Date: Fri, 14 Oct 2005 14:28:09 +0100 Subject: [PATCH] [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: Thomas Osterried DL9SAU Signed-off-by: Ralf Baechle DL5RB Signed-off-by: Jeff Garzik --- drivers/net/hamradio/Kconfig | 1 + drivers/net/hamradio/mkiss.c | 178 +++++++++++++++++++++++++++++------ 2 files changed, 148 insertions(+), 31 deletions(-) diff --git a/drivers/net/hamradio/Kconfig b/drivers/net/hamradio/Kconfig index de087cd609..896aa02000 100644 --- a/drivers/net/hamradio/Kconfig +++ b/drivers/net/hamradio/Kconfig @@ -1,6 +1,7 @@ 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 diff --git a/drivers/net/hamradio/mkiss.c b/drivers/net/hamradio/mkiss.c index 331a75c8ae..7961f5b41c 100644 --- a/drivers/net/hamradio/mkiss.c +++ b/drivers/net/hamradio/mkiss.c @@ -14,13 +14,14 @@ * * Copyright (C) Hans Alblas PE1AYX * Copyright (C) 2004, 05 Ralf Baechle DL5RB + * Copyright (C) 2004, 05 Thomas Osterried DL9SAU */ - #include #include #include #include #include +#include #include #include #include @@ -39,11 +40,6 @@ #include -#ifdef CONFIG_INET -#include -#include -#endif - #define AX_MTU 236 /* SLIP/KISS protocol characters. */ @@ -80,9 +76,13 @@ struct mkiss { int mode; int crcmode; /* MW: for FlexNet, SMACK etc. */ -#define CRC_MODE_NONE 0 -#define CRC_MODE_FLEX 1 -#define CRC_MODE_SMACK 2 + 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 */ @@ -237,19 +252,42 @@ 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++; + 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; + *ax->rbuff &= ~0x20; } } spin_unlock_bh(&ax->buflock); @@ -417,20 +455,69 @@ 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); - case CRC_MODE_FLEX: - *p |= 0x20; - crc = calc_crc_flex(p, len); - count = kiss_esc_crc(p, (unsigned char *)ax->xbuff, crc, len+2); - break; + 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); + count = kiss_esc_crc(p, (unsigned char *)ax->xbuff, crc, len+2); + break; + + default: + count = kiss_esc(p, (unsigned char *)ax->xbuff, len); + } + } - default: - count = kiss_esc(p, (unsigned char *)ax->xbuff, len); - break; - } - set_bit(TTY_DO_WRITE_WAKEUP, &ax->tty->flags); actual = ax->tty->driver->write(ax->tty, ax->xbuff, count); ax->stats.tx_packets++; @@ -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 "); 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); -- 2.39.5