ppp.c

unix and linux net driver

/*  PPP for Linux
 *
 *  Michael Callahan <[e-mail]>
 *  Al Longyear <[e-mail]>
 *  Extensively rewritten by Paul Mackerras <[e-mail]>
 *
 *  ==FILEVERSION 990910==
 *
 *  NOTE TO MAINTAINERS:
 *     If you modify this file at all, please set the number above to the
 *     date of the modification as YYMMDD (year month day).
 *     ppp.c is shipped with a PPP distribution as well as with the kernel;
 *     if everyone increases the FILEVERSION number above, then scripts
 *     can do the right thing when deciding whether to install a new ppp.c
 *     file.  Don't change the format of that line otherwise, so the
 *     installation script can recognize it.
 */

/*
   Sources:

   slip.c

   RFC1331: The Point-to-Point Protocol (PPP) for the Transmission of
   Multi-protocol Datagrams over Point-to-Point Links

   RFC1332: IPCP

   ppp-2.0

   Flags for this module (any combination is acceptable for testing.):

   OPTIMIZE_FLAG_TIME - Number of jiffies to force sending of leading flag
			character. This is normally set to ((HZ * 3) / 2).
			This is 1.5 seconds. If zero then the leading
			flag is always sent.

   CHECK_CHARACTERS   - Enable the checking on all received characters for
			8 data bits, no parity. This adds a small amount of
			processing for each received character.
*/

#define OPTIMIZE_FLAG_TIME	((HZ * 3)/2)
#define CHECK_CHARACTERS	1

#define PPP_MAX_RCV_QLEN	32	/* max # frames we queue up for pppd */

/* $Id: ppp.c,v 1.33 1999/12/23 01:48:45 paulus Exp $ */

#include <linux/version.h>
#include <linux/config.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/types.h>
#include <linux/fcntl.h>
#include <linux/interrupt.h>
#include <linux/ptrace.h>

/* a macro to generate linux version number codes */
#define VERSION(major,minor,patch) (((((major)<<8)+(minor))<<8)+(patch))

#if LINUX_VERSION_CODE < VERSION(2,1,14)
#include <linux/ioport.h>
#endif

#if LINUX_VERSION_CODE >= VERSION(2,1,23)
#include <linux/poll.h>
#endif

#include <linux/in.h>
#include <linux/malloc.h>
#include <linux/tty.h>
#include <linux/errno.h>
#include <linux/sched.h>	/* to get the struct task_struct */
#include <linux/string.h>	/* used in new tty drivers */
#include <linux/signal.h>	/* used in new tty drivers */
#include <asm/system.h>
#include <asm/bitops.h>
#include <linux/if.h>
#include <linux/if_ether.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <linux/inet.h>
#include <linux/ioctl.h>
#include <linux/ip.h>
#include <linux/tcp.h>
#include <linux/if_arp.h>
#include <net/slhc_vj.h>

#define fcstab	ppp_crc16_table		/* Name of the table in the kernel */
#include <linux/ppp_defs.h>

#include <linux/socket.h>
#include <linux/if_ppp.h>
#include <linux/if_pppvar.h>
#include <linux/ppp-comp.h>

#ifdef CONFIG_KMOD
#include <linux/kmod.h>
#endif
#ifdef CONFIG_KERNELD
#include <linux/kerneld.h>
#endif

#undef PPP_VERSION
#define PPP_VERSION	"2.3.11"

#if LINUX_VERSION_CODE >= VERSION(2,1,4)

#if LINUX_VERSION_CODE >= VERSION(2,1,5)
#include <asm/uaccess.h>
#else
#include <asm/segment.h>
#endif

#define GET_USER	get_user
#define PUT_USER	put_user
#define COPY_FROM_USER	copy_from_user
#define COPY_TO_USER	copy_to_user

#else  /* 2.0.x and 2.1.x before 2.1.4 */

#define GET_USER(val, src)	\
	(verify_area(VERIFY_READ, src, sizeof(*src))? -EFAULT: \
	 ((val) = get_user(src), 0))
#define PUT_USER(val, dst)	\
	(verify_area(VERIFY_WRITE, dst, sizeof(*dst))? -EFAULT: \
	 (put_user(val, dst), 0))
#define COPY_FROM_USER(dst, src, size)	\
	(verify_area(VERIFY_READ, src, size)? -EFAULT: \
	 (memcpy_fromfs(dst, src, size), 0))
#define COPY_TO_USER(dst, src, size)	\
	(verify_area(VERIFY_WRITE, dst, size)? -EFAULT: \
	 (memcpy_tofs(dst, src, size), 0))

#endif /* < 2.1.4 */

#if LINUX_VERSION_CODE < VERSION(2,1,37)
#define test_and_set_bit(nr, addr)	set_bit(nr, addr)
#endif

#if LINUX_VERSION_CODE < VERSION(2,1,25)
#define net_device_stats	enet_statistics
#endif

#if LINUX_VERSION_CODE < VERSION(2,1,57)
#define signal_pending(tsk)	((tsk)->signal & ~(tsk)->blocked)
#endif

#if LINUX_VERSION_CODE < VERSION(2,1,60)
typedef int		rw_ret_t;
typedef unsigned int	rw_count_t;
#else
typedef ssize_t		rw_ret_t;
typedef size_t		rw_count_t;
#endif

#if LINUX_VERSION_CODE < VERSION(2,1,86)
#define KFREE_SKB(s)	dev_kfree_skb((s), FREE_WRITE)
#else
#define KFREE_SKB(s)	kfree_skb(s)
#endif

#if LINUX_VERSION_CODE < VERSION(2,1,15)
#define LIBERATE_SKB(s)	((s)->free = 1)
#else
#define LIBERATE_SKB(s)	do { } while (0)
#endif

#if LINUX_VERSION_CODE < VERSION(2,1,95)
#define SUSER()		suser()
#else
#define SUSER()		capable(CAP_NET_ADMIN)
#endif

#if LINUX_VERSION_CODE < VERSION(2,2,0)
#define wmb()		mb()
#endif

/*
 * Local functions
 */

static int ppp_register_compressor (struct compressor *cp);
static void ppp_unregister_compressor (struct compressor *cp);

static void ppp_async_init(struct ppp *ppp);
static void ppp_async_release(struct ppp *ppp);
static int ppp_tty_sync_push(struct ppp *ppp);
static int ppp_tty_push(struct ppp *ppp);
static int ppp_async_encode(struct ppp *ppp);
static int ppp_async_send(struct ppp *, struct sk_buff *);
static int ppp_sync_send(struct ppp *, struct sk_buff *);
static void ppp_tty_flush_output(struct ppp *);

static int ppp_ioctl(struct ppp *, unsigned int, unsigned long);
static int ppp_set_compression (struct ppp *ppp, struct ppp_option_data *odp);
static void ppp_proto_ccp(struct ppp *ppp, __u8 *dp, int len, int rcvd);
static void ppp_ccp_closed(struct ppp *ppp);
static int ppp_receive_frame(struct ppp *, struct sk_buff *);
static void ppp_receive_error(struct ppp *ppp);
static void ppp_output_wakeup(struct ppp *ppp);
static void ppp_send_ctrl(struct ppp *ppp, struct sk_buff *skb);
static void ppp_send_frame(struct ppp *ppp, struct sk_buff *skb);
static void ppp_send_frames(struct ppp *ppp);
static struct sk_buff *ppp_vj_compress(struct ppp *ppp, struct sk_buff *skb);

static struct ppp *ppp_find (int pid_value);
static struct ppp *ppp_alloc (void);
static void ppp_generic_init(struct ppp *ppp);
static void ppp_release(struct ppp *ppp);
static void ppp_print_buffer (const char *, const __u8 *, int);
static struct compressor *find_compressor (int type);

#ifndef OPTIMIZE_FLAG_TIME
#define OPTIMIZE_FLAG_TIME	0
#endif

/*
 * Parameters which may be changed via insmod.
 */

static int  flag_time = OPTIMIZE_FLAG_TIME;
#if LINUX_VERSION_CODE >= VERSION(2,1,19) 
MODULE_PARM(flag_time, "i");
#endif

#define CHECK_PPP_MAGIC(ppp)	do { \
	if (ppp->magic != PPP_MAGIC) { \
		printk(ppp_magic_warn, ppp, __FILE__, __LINE__); \
	} \
} while (0)
#define CHECK_PPP(a)	do { \
	CHECK_PPP_MAGIC(ppp); \
	if (!ppp->inuse) { \
		printk(ppp_warning, __LINE__); \
		return a; \
	} \
} while (0)
#define CHECK_PPP_VOID() do { \
	CHECK_PPP_MAGIC(ppp); \
	if (!ppp->inuse) { \
		printk(ppp_warning, __LINE__); \
		return; \
	} \
} while (0)

#define tty2ppp(tty)	((struct ppp *) ((tty)->disc_data))
#define dev2ppp(dev)	((struct ppp *) ((dev)->priv))
#define ppp2tty(ppp)	((ppp)->tty)
#define ppp2dev(ppp)	(&(ppp)->dev)

static struct ppp *ppp_list = NULL;
static struct ppp *ppp_last = NULL;

/* Define these strings only once for all macro invocations */
static char ppp_warning[] = KERN_WARNING "PPP: ALERT! not INUSE! %d\n";
static char ppp_magic_warn[] = KERN_WARNING "bad magic for ppp %p at %s:%d\n";

static char szVersion[]		= PPP_VERSION;

#if LINUX_VERSION_CODE < VERSION(2,1,18)
static struct symbol_table ppp_syms = {
#include <linux/symtab_begin.h>
	X(ppp_register_compressor),
	X(ppp_unregister_compressor),
#include <linux/symtab_end.h>
};
#else
EXPORT_SYMBOL(ppp_register_compressor);
EXPORT_SYMBOL(ppp_unregister_compressor);
#endif

/*************************************************************
 * LINE DISCIPLINE SUPPORT
 *    The following code implements the PPP line discipline
 *    and supports using PPP on an async serial line.
 *************************************************************/

#define in_xmap(ppp,c)	(ppp->xmit_async_map[(c) >> 5] & (1 << ((c) & 0x1f)))
#define in_rmap(ppp,c)	((((unsigned int) (__u8) (c)) < 0x20) && \
			ppp->recv_async_map & (1 << (c)))

/*
 * TTY callbacks
 */

static rw_ret_t ppp_tty_read(struct tty_struct *, struct file *, __u8 *,
			     rw_count_t);
static rw_ret_t ppp_tty_write(struct tty_struct *, struct file *, const __u8 *,
			      rw_count_t);
static int ppp_tty_ioctl(struct tty_struct *, struct file *, unsigned int,
			 unsigned long);
#if LINUX_VERSION_CODE < VERSION(2,1,23)
static int ppp_tty_select(struct tty_struct *tty, struct inode *inode,
			struct file *filp, int sel_type, select_table * wait);
#else
static unsigned int ppp_tty_poll(struct tty_struct *tty, struct file *filp,
				 poll_table * wait);
#endif
static int ppp_tty_open (struct tty_struct *);
static void ppp_tty_close (struct tty_struct *);
static int ppp_tty_room (struct tty_struct *tty);
static void ppp_tty_receive (struct tty_struct *tty, const __u8 * cp,
			     char *fp, int count);
static void ppp_tty_wakeup (struct tty_struct *tty);

__u16 ppp_crc16_table[256] =
{
	0x0000, 0x1189, 0x2312, 0x329b, 0x4624, 0x57ad, 0x6536, 0x74bf,
	0x8c48, 0x9dc1, 0xaf5a, 0xbed3, 0xca6c, 0xdbe5, 0xe97e, 0xf8f7,
	0x1081, 0x0108, 0x3393, 0x221a, 0x56a5, 0x472c, 0x75b7, 0x643e,
	0x9cc9, 0x8d40, 0xbfdb, 0xae52, 0xdaed, 0xcb64, 0xf9ff, 0xe876,
	0x2102, 0x308b, 0x0210, 0x1399, 0x6726, 0x76af, 0x4434, 0x55bd,
	0xad4a, 0xbcc3, 0x8e58, 0x9fd1, 0xeb6e, 0xfae7, 0xc87c, 0xd9f5,
	0x3183, 0x200a, 0x1291, 0x0318, 0x77a7, 0x662e, 0x54b5, 0x453c,
	0xbdcb, 0xac42, 0x9ed9, 0x8f50, 0xfbef, 0xea66, 0xd8fd, 0xc974,
	0x4204, 0x538d, 0x6116, 0x709f, 0x0420, 0x15a9, 0x2732, 0x36bb,
	0xce4c, 0xdfc5, 0xed5e, 0xfcd7, 0x8868, 0x99e1, 0xab7a, 0xbaf3,
	0x5285, 0x430c, 0x7197, 0x601e, 0x14a1, 0x0528, 0x37b3, 0x263a,
	0xdecd, 0xcf44, 0xfddf, 0xec56, 0x98e9, 0x8960, 0xbbfb, 0xaa72,
	0x6306, 0x728f, 0x4014, 0x519d, 0x2522, 0x34ab, 0x0630, 0x17b9,
	0xef4e, 0xfec7, 0xcc5c, 0xddd5, 0xa96a, 0xb8e3, 0x8a78, 0x9bf1,
	0x7387, 0x620e, 0x5095, 0x411c, 0x35a3, 0x242a, 0x16b1, 0x0738,
	0xffcf, 0xee46, 0xdcdd, 0xcd54, 0xb9eb, 0xa862, 0x9af9, 0x8b70,
	0x8408, 0x9581, 0xa71a, 0xb693, 0xc22c, 0xd3a5, 0xe13e, 0xf0b7,
	0x0840, 0x19c9, 0x2b52, 0x3adb, 0x4e64, 0x5fed, 0x6d76, 0x7cff,
	0x9489, 0x8500, 0xb79b, 0xa612, 0xd2ad, 0xc324, 0xf1bf, 0xe036,
	0x18c1, 0x0948, 0x3bd3, 0x2a5a, 0x5ee5, 0x4f6c, 0x7df7, 0x6c7e,
	0xa50a, 0xb483, 0x8618, 0x9791, 0xe32e, 0xf2a7, 0xc03c, 0xd1b5,
	0x2942, 0x38cb, 0x0a50, 0x1bd9, 0x6f66, 0x7eef, 0x4c74, 0x5dfd,
	0xb58b, 0xa402, 0x9699, 0x8710, 0xf3af, 0xe226, 0xd0bd, 0xc134,
	0x39c3, 0x284a, 0x1ad1, 0x0b58, 0x7fe7, 0x6e6e, 0x5cf5, 0x4d7c,
	0xc60c, 0xd785, 0xe51e, 0xf497, 0x8028, 0x91a1, 0xa33a, 0xb2b3,
	0x4a44, 0x5bcd, 0x6956, 0x78df, 0x0c60, 0x1de9, 0x2f72, 0x3efb,
	0xd68d, 0xc704, 0xf59f, 0xe416, 0x90a9, 0x8120, 0xb3bb, 0xa232,
	0x5ac5, 0x4b4c, 0x79d7, 0x685e, 0x1ce1, 0x0d68, 0x3ff3, 0x2e7a,
	0xe70e, 0xf687, 0xc41c, 0xd595, 0xa12a, 0xb0a3, 0x8238, 0x93b1,
	0x6b46, 0x7acf, 0x4854, 0x59dd, 0x2d62, 0x3ceb, 0x0e70, 0x1ff9,
	0xf78f, 0xe606, 0xd49d, 0xc514, 0xb1ab, 0xa022, 0x92b9, 0x8330,
	0x7bc7, 0x6a4e, 0x58d5, 0x495c, 0x3de3, 0x2c6a, 0x1ef1, 0x0f78
};
#if LINUX_VERSION_CODE >= VERSION(2,1,18)
EXPORT_SYMBOL(ppp_crc16_table);
#endif

#ifdef CHECK_CHARACTERS
static __u32 paritytab[8] =
{
	0x96696996, 0x69969669, 0x69969669, 0x96696996,
	0x69969669, 0x96696996, 0x96696996, 0x69969669
};
#endif

/*
 * This procedure is called at initialization time to register
 * the PPP line discipline.
 */
static int
ppp_first_time(void)
{
	static struct tty_ldisc	ppp_ldisc;
	int    status;

	printk(KERN_INFO
	       "PPP: version %s (demand dialling)"
	       "\n", szVersion);

#ifndef MODULE /* slhc module logic has its own copyright announcement */
	printk(KERN_INFO
	       "TCP compression code copyright 1989 Regents of the "
	       "University of California\n");
#endif

	/*
	 * Register the tty discipline
	 */
	(void) memset (&ppp_ldisc, 0, sizeof (ppp_ldisc));
	ppp_ldisc.magic		= TTY_LDISC_MAGIC;
#if LINUX_VERSION_CODE >= VERSION(2,1,28)
	ppp_ldisc.name          = "ppp";
#endif
	ppp_ldisc.open		= ppp_tty_open;
	ppp_ldisc.close		= ppp_tty_close;
	ppp_ldisc.read		= ppp_tty_read;
	ppp_ldisc.write		= ppp_tty_write;
	ppp_ldisc.ioctl		= ppp_tty_ioctl;
#if LINUX_VERSION_CODE < VERSION(2,1,23)
	ppp_ldisc.select	= ppp_tty_select;
#else
	ppp_ldisc.poll		= ppp_tty_poll;
#endif
	ppp_ldisc.receive_room	= ppp_tty_room;
	ppp_ldisc.receive_buf	= ppp_tty_receive;
	ppp_ldisc.write_wakeup	= ppp_tty_wakeup;

	status = tty_register_ldisc (N_PPP, &ppp_ldisc);
	if (status == 0)
		printk(KERN_INFO "PPP line discipline registered.\n");
	else
		printk(KERN_ERR "error registering line discipline: %d\n",
		       status);
	return status;
}


#ifndef MODULE
/*
 * Called at boot time if the PPP driver is compiled into the kernel.
 */
int
ppp_init(struct device *dev)
{
	static int first_time = 1;
	int    answer = 0;

	if (first_time) {
		first_time = 0;
		answer	   = ppp_first_time();
#if LINUX_VERSION_CODE < VERSION(2,1,18)
		if (answer == 0)
			(void) register_symtab(&ppp_syms);
#endif
	}
	if (answer == 0)
		answer = -ENODEV;
	return answer;
}
#endif

/*
 * Initialize the async-specific parts of the ppp structure.
 */
static void
ppp_async_init(struct ppp *ppp)
{
	ppp->escape = 0;
	ppp->toss   = 0xE0;
	ppp->tty_pushing = 0;

	memset (ppp->xmit_async_map, 0, sizeof (ppp->xmit_async_map));
	ppp->xmit_async_map[0] = 0xffffffff;
	ppp->xmit_async_map[3] = 0x60000000;
	ppp->recv_async_map    = 0xffffffff;

	ppp->tpkt = NULL;
	ppp->tfcs = PPP_INITFCS;
	ppp->optr = ppp->obuf;
	ppp->olim = ppp->obuf;

	ppp->rpkt = NULL;
	ppp->rfcs = PPP_INITFCS;

	ppp->tty  = NULL;
	ppp->backup_tty = NULL;

	ppp->bytes_sent = 0;
	ppp->bytes_rcvd = 0;
}

/*
 * Clean up the async-specific parts of the ppp structure.
 */
static void
ppp_async_release(struct ppp *ppp)
{
	struct sk_buff *skb;

	if ((skb = ppp->rpkt) != NULL)
		KFREE_SKB(skb);
	ppp->rpkt = NULL;
	if ((skb = ppp->tpkt) != NULL)
		KFREE_SKB(skb);
	ppp->tpkt = NULL;
}

/*
 * TTY callback.
 *
 * Called when the tty discipline is switched to PPP.
 */

static int
ppp_tty_open (struct tty_struct *tty)
{
	struct ppp *ppp;

	/*
	 * Allocate a ppp structure to use.
	 */
	tty->disc_data = NULL;
	ppp = ppp_find(current->pid);
	if (ppp != NULL) {
		/*
		 * If we are taking over a ppp unit which is currently
		 * connected to a loopback pty, there's not much to do.
		 */
		CHECK_PPP(-EINVAL);

	} else {
		ppp = ppp_alloc();
		if (ppp == NULL) {
			printk(KERN_ERR "ppp_alloc failed\n");
			return -ENFILE;
		}

		/*
		 * Initialize the control block
		 */
		ppp_generic_init(ppp);
		ppp_async_init(ppp);

		MOD_INC_USE_COUNT;
	}

	tty->disc_data = ppp;
	ppp->tty       = tty;

	/*
	 * Flush any pending characters in the driver
	 */
	if (tty->driver.flush_buffer)
		tty->driver.flush_buffer (tty);

	return ppp->line;
}

/*
 * TTY callback.
 *
 * Called when the line discipline is changed to something
 * else, the tty is closed, or the tty detects a hangup.
 */

static void
ppp_tty_close (struct tty_struct *tty)
{
	struct ppp *ppp = tty2ppp(tty);

	if (ppp == NULL)
		return;
	tty->disc_data = NULL;
	if (ppp->magic != PPP_MAGIC) {
		printk(KERN_WARNING "ppp_tty_close: bogus\n");
		return;
	}
	if (!ppp->inuse) {
		printk(KERN_WARNING "ppp_tty_close: not inuse\n");
		ppp->tty = ppp->backup_tty = 0;
		return;
	}
	if (tty == ppp->backup_tty)
		ppp->backup_tty = 0;
	if (tty != ppp->tty)
		return;
	if (ppp->backup_tty) {