af_ax25.c

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/*
 *	AX.25 release 038
 *
 *	This code REQUIRES 2.1.15 or higher/ NET3.038
 *
 *	This module:
 *		This module is free software; you can redistribute it and/or
 *		modify it under the terms of the GNU General Public License
 *		as published by the Free Software Foundation; either version
 *		2 of the License, or (at your option) any later version.
 *
 *	History
 *	AX.25 006	Alan(GW4PTS)		Nearly died of shock - it's working 8-)
 *	AX.25 007	Alan(GW4PTS)		Removed the silliest bugs
 *	AX.25 008	Alan(GW4PTS)		Cleaned up, fixed a few state machine problems, added callbacks
 *	AX.25 009	Alan(GW4PTS)		Emergency patch kit to fix memory corruption
 * 	AX.25 010	Alan(GW4PTS)		Added RAW sockets/Digipeat.
 *	AX.25 011	Alan(GW4PTS)		RAW socket and datagram fixes (thanks) - Raw sendto now gets PID right
 *						datagram sendto uses correct target address.
 *	AX.25 012	Alan(GW4PTS)		Correct incoming connection handling, send DM to failed connects.
 *						Use skb->data not skb+1. Support sk->priority correctly.
 *						Correct receive on SOCK_DGRAM.
 *	AX.25 013	Alan(GW4PTS)		Send DM to all unknown frames, missing initialiser fixed
 *						Leave spare SSID bits set (DAMA etc) - thanks for bug report,
 *						removed device registration (it's not used or needed). Clean up for
 *						gcc 2.5.8. PID to AX25_P_
 *	AX.25 014	Alan(GW4PTS)		Cleanup and NET3 merge
 *	AX.25 015	Alan(GW4PTS)		Internal test version.
 *	AX.25 016	Alan(GW4PTS)		Semi Internal version for PI card
 *						work.
 *	AX.25 017	Alan(GW4PTS)		Fixed some small bugs reported by
 *						G4KLX
 *	AX.25 018	Alan(GW4PTS)		Fixed a small error in SOCK_DGRAM
 *	AX.25 019	Alan(GW4PTS)		Clean ups for the non INET kernel and device ioctls in AX.25
 *	AX.25 020	Jonathan(G4KLX)		/proc support and other changes.
 *	AX.25 021	Alan(GW4PTS)		Added AX25_T1, AX25_N2, AX25_T3 as requested.
 *	AX.25 022	Jonathan(G4KLX)		More work on the ax25 auto router and /proc improved (again)!
 *			Alan(GW4PTS)		Added TIOCINQ/OUTQ
 *	AX.25 023	Alan(GW4PTS)		Fixed shutdown bug
 *	AX.25 023	Alan(GW4PTS)		Linus changed timers
 *	AX.25 024	Alan(GW4PTS)		Small bug fixes
 *	AX.25 025	Alan(GW4PTS)		More fixes, Linux 1.1.51 compatibility stuff, timers again!
 *	AX.25 026	Alan(GW4PTS)		Small state fix.
 *	AX.25 027	Alan(GW4PTS)		Socket close crash fixes.
 *	AX.25 028	Alan(GW4PTS)		Callsign control including settings per uid.
 *						Small bug fixes.
 *						Protocol set by sockets only.
 *						Small changes to allow for start of NET/ROM layer.
 *	AX.25 028a	Jonathan(G4KLX)		Changes to state machine.
 *	AX.25 028b	Jonathan(G4KLX)		Extracted ax25 control block
 *						from sock structure.
 *	AX.25 029	Alan(GW4PTS)		Combined 028b and some KA9Q code
 *			Jonathan(G4KLX)		and removed all the old Berkeley, added IP mode registration.
 *			Darryl(G7LED)		stuff. Cross-port digipeating. Minor fixes and enhancements.
 *			Alan(GW4PTS)		Missed suser() on axassociate checks
 *	AX.25 030	Alan(GW4PTS)		Added variable length headers.
 *			Jonathan(G4KLX)		Added BPQ Ethernet interface.
 *			Steven(GW7RRM)		Added digi-peating control ioctl.
 *						Added extended AX.25 support.
 *						Added AX.25 frame segmentation.
 *			Darryl(G7LED)		Changed connect(), recvfrom(), sendto() sockaddr/addrlen to
 *						fall inline with bind() and new policy.
 *						Moved digipeating ctl to new ax25_dev structs.
 *						Fixed ax25_release(), set TCP_CLOSE, wakeup app
 *						context, THEN make the sock dead.
 *			Alan(GW4PTS)		Cleaned up for single recvmsg methods.
 *			Alan(GW4PTS)		Fixed not clearing error on connect failure.
 *	AX.25 031	Jonathan(G4KLX)		Added binding to any device.
 *			Joerg(DL1BKE)		Added DAMA support, fixed (?) digipeating, fixed buffer locking
 *						for "virtual connect" mode... Result: Probably the
 *						"Most Buggiest Code You've Ever Seen" (TM)
 *			HaJo(DD8NE)		Implementation of a T5 (idle) timer
 *			Joerg(DL1BKE)		Renamed T5 to IDLE and changed behaviour:
 *						the timer gets reloaded on every received or transmitted
 *						I frame for IP or NETROM. The idle timer is not active
 *						on "vanilla AX.25" connections. Furthermore added PACLEN
 *						to provide AX.25-layer based fragmentation (like WAMPES)
 *      AX.25 032	Joerg(DL1BKE)		Fixed DAMA timeout error.
 *						ax25_send_frame() limits the number of enqueued
 *						datagrams per socket.
 *	AX.25 033	Jonathan(G4KLX)		Removed auto-router.
 *			Hans(PE1AYX)		Converted to Module.
 *			Joerg(DL1BKE)		Moved BPQ Ethernet to separate driver.
 *	AX.25 034	Jonathan(G4KLX)		2.1 changes
 *			Alan(GW4PTS)		Small POSIXisations
 *	AX.25 035	Alan(GW4PTS)		Started fixing to the new
 *						format.
 *			Hans(PE1AYX)		Fixed interface to IP layer.
 *			Alan(GW4PTS)		Added asynchronous support.
 *			Frederic(F1OAT)		Support for pseudo-digipeating.
 *			Jonathan(G4KLX)		Support for packet forwarding.
 *	AX.25 036	Jonathan(G4KLX)		Major restructuring.
 *			Joerg(DL1BKE)		Fixed DAMA Slave.
 *			Jonathan(G4KLX)		Fix wildcard listen parameter setting.
 *	AX.25 037	Jonathan(G4KLX)		New timer architecture.
 *      AX.25 038       Matthias(DG2FEF)        Small fixes to the syscall interface to make kernel
 *                                              independent of AX25_MAX_DIGIS used by applications.
 *                      Tomi(OH2BNS)            Fixed ax25_getname().
 *			Joerg(DL1BKE)		Starting to phase out the support for full_sockaddr_ax25
 *						with only 6 digipeaters and sockaddr_ax25 in ax25_bind(),
 *						ax25_connect() and ax25_sendmsg()
 *			Joerg(DL1BKE)		Added support for SO_BINDTODEVICE
 *			Arnaldo C. Melo		s/suser/capable(CAP_NET_ADMIN)/, some more cleanups
 *			Michal Ostrowski	Module initialization cleanup.
 *			Jeroen(PE1RXQ)		Use sock_orphan() on release.
 */

#include <linux/config.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/timer.h>
#include <linux/string.h>
#include <linux/sockios.h>
#include <linux/net.h>
#include <net/ax25.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <linux/if_arp.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#include <linux/fcntl.h>
#include <linux/termios.h>	/* For TIOCINQ/OUTQ */
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/notifier.h>
#include <linux/proc_fs.h>
#include <linux/stat.h>
#include <linux/netfilter.h>
#include <linux/sysctl.h>
#include <linux/init.h>
#include <net/ip.h>
#include <net/arp.h>



ax25_cb *volatile ax25_list;

static struct proto_ops ax25_proto_ops;

/*
 *	Free an allocated ax25 control block. This is done to centralise
 *	the MOD count code.
 */
void ax25_free_cb(ax25_cb *ax25)
{
	if (ax25->digipeat != NULL) {
		kfree(ax25->digipeat);
		ax25->digipeat = NULL;
	}

	kfree(ax25);

	MOD_DEC_USE_COUNT;
}

static void ax25_free_sock(struct sock *sk)
{
	ax25_free_cb(sk->protinfo.ax25);
}

/*
 *	Socket removal during an interrupt is now safe.
 */
static void ax25_remove_socket(ax25_cb *ax25)
{
	ax25_cb *s;
	unsigned long flags;

	save_flags(flags); cli();

	if ((s = ax25_list) == ax25) {
		ax25_list = s->next;
		restore_flags(flags);
		return;
	}

	while (s != NULL && s->next != NULL) {
		if (s->next == ax25) {
			s->next = ax25->next;
			restore_flags(flags);
			return;
		}

		s = s->next;
	}

	restore_flags(flags);
}

/*
 *	Kill all bound sockets on a dropped device.
 */
static void ax25_kill_by_device(struct net_device *dev)
{
	ax25_dev *ax25_dev;
	ax25_cb *s;

	if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL)
		return;

	for (s = ax25_list; s != NULL; s = s->next) {
		if (s->ax25_dev == ax25_dev) {
			s->ax25_dev = NULL;
			ax25_disconnect(s, ENETUNREACH);
		}
	}
}

/*
 *	Handle device status changes.
 */
static int ax25_device_event(struct notifier_block *this,unsigned long event, void *ptr)
{
	struct net_device *dev = (struct net_device *)ptr;

	/* Reject non AX.25 devices */
	if (dev->type != ARPHRD_AX25)
		return NOTIFY_DONE;

	switch (event) {
		case NETDEV_UP:
			ax25_dev_device_up(dev);
			break;
		case NETDEV_DOWN:
			ax25_kill_by_device(dev);
			ax25_rt_device_down(dev);
			ax25_dev_device_down(dev);
			break;
		default:
			break;
	}

	return NOTIFY_DONE;
}

/*
 *	Add a socket to the bound sockets list.
 */
void ax25_insert_socket(ax25_cb *ax25)
{
	unsigned long flags;

	save_flags(flags);
	cli();

	ax25->next = ax25_list;
	ax25_list  = ax25;

	restore_flags(flags);
}

/*
 *	Find a socket that wants to accept the SABM we have just
 *	received.
 */
struct sock *ax25_find_listener(ax25_address *addr, int digi, struct net_device *dev, int type)
{
	unsigned long flags;
	ax25_cb *s;

	save_flags(flags);
	cli();

	for (s = ax25_list; s != NULL; s = s->next) {
		if ((s->iamdigi && !digi) || (!s->iamdigi && digi))
			continue;
		if (s->sk != NULL && ax25cmp(&s->source_addr, addr) == 0 && s->sk->type == type && s->sk->state == TCP_LISTEN) {
			/* If device is null we match any device */
			if (s->ax25_dev == NULL || s->ax25_dev->dev == dev) {
				restore_flags(flags);
				return s->sk;
			}
		}
	}

	restore_flags(flags);
	return NULL;
}

/*
 *	Find an AX.25 socket given both ends.
 */
struct sock *ax25_find_socket(ax25_address *my_addr, ax25_address *dest_addr, int type)
{
	ax25_cb *s;
	unsigned long flags;

	save_flags(flags);
	cli();

	for (s = ax25_list; s != NULL; s = s->next) {
		if (s->sk != NULL && ax25cmp(&s->source_addr, my_addr) == 0 && ax25cmp(&s->dest_addr, dest_addr) == 0 && s->sk->type == type) {
			restore_flags(flags);
			return s->sk;
		}
	}

	restore_flags(flags);

	return NULL;
}

/*
 *	Find an AX.25 control block given both ends. It will only pick up
 *	floating AX.25 control blocks or non Raw socket bound control blocks.
 */
ax25_cb *ax25_find_cb(ax25_address *src_addr, ax25_address *dest_addr, ax25_digi *digi, struct net_device *dev)
{
	ax25_cb *s;
	unsigned long flags;

	save_flags(flags);
	cli();

	for (s = ax25_list; s != NULL; s = s->next) {
		if (s->sk != NULL && s->sk->type != SOCK_SEQPACKET)
			continue;
		if (s->ax25_dev == NULL)
			continue;
		if (ax25cmp(&s->source_addr, src_addr) == 0 && ax25cmp(&s->dest_addr, dest_addr) == 0 && s->ax25_dev->dev == dev) {
			if (digi != NULL && digi->ndigi != 0) {
				if (s->digipeat == NULL)
					continue;
				if (ax25digicmp(s->digipeat, digi) != 0)
					continue;
			} else {
				if (s->digipeat != NULL && s->digipeat->ndigi != 0)
					continue;
			}
			restore_flags(flags);
			return s;
		}
	}

	restore_flags(flags);

	return NULL;
}

/*
 *	Look for any matching address - RAW sockets can bind to arbitrary names
 */
struct sock *ax25_addr_match(ax25_address *addr)
{
	unsigned long flags;
	ax25_cb *s;

	save_flags(flags);
	cli();

	for (s = ax25_list; s != NULL; s = s->next) {
		if (s->sk != NULL && ax25cmp(&s->source_addr, addr) == 0 && s->sk->type == SOCK_RAW) {
			restore_flags(flags);
			return s->sk;
		}
	}

	restore_flags(flags);

	return NULL;
}

void ax25_send_to_raw(struct sock *sk, struct sk_buff *skb, int proto)
{
	struct sk_buff *copy;

	while (sk != NULL) {
		if (sk->type == SOCK_RAW &&
		    sk->protocol == proto &&
		    atomic_read(&sk->rmem_alloc) <= sk->rcvbuf) {
			if ((copy = skb_clone(skb, GFP_ATOMIC)) == NULL)
				return;

			if (sock_queue_rcv_skb(sk, copy) != 0)
				kfree_skb(copy);
		}

		sk = sk->next;
	}
}

/*
 *	Deferred destroy.
 */
void ax25_destroy_socket(ax25_cb *);

/*
 *	Handler for deferred kills.
 */
static void ax25_destroy_timer(unsigned long data)
{
	ax25_destroy_socket((ax25_cb *)data);
}

/*
 *	This is called from user mode and the timers. Thus it protects itself against
 *	interrupt users but doesn't worry about being called during work.
 *	Once it is removed from the queue no interrupt or bottom half will
 *	touch it and we are (fairly 8-) ) safe.
 */
void ax25_destroy_socket(ax25_cb *ax25)	/* Not static as it's used by the timer */
{
	struct sk_buff *skb;
	unsigned long flags;

	save_flags(flags); cli();

	ax25_stop_heartbeat(ax25);
	ax25_stop_t1timer(ax25);
	ax25_stop_t2timer(ax25);
	ax25_stop_t3timer(ax25);
	ax25_stop_idletimer(ax25);

	ax25_remove_socket(ax25);
	ax25_clear_queues(ax25);	/* Flush the queues */

	if (ax25->sk != NULL) {
		while ((skb = skb_dequeue(&ax25->sk->receive_queue)) != NULL) {
			if (skb->sk != ax25->sk) {			/* A pending connection */
				skb->sk->dead = 1;	/* Queue the unaccepted socket for death */
				ax25_start_heartbeat(skb->sk->protinfo.ax25);
				skb->sk->protinfo.ax25->state = AX25_STATE_0;
			}

			kfree_skb(skb);
		}
	}

	if (ax25->sk != NULL) {
		if (atomic_read(&ax25->sk->wmem_alloc) != 0 ||
		    atomic_read(&ax25->sk->rmem_alloc) != 0) {
			/* Defer: outstanding buffers */
			init_timer(&ax25->timer);
			ax25->timer.expires  = jiffies + 10 * HZ;
			ax25->timer.function = ax25_destroy_timer;
			ax25->timer.data     = (unsigned long)ax25;
			add_timer(&ax25->timer);
		} else {
			sk_free(ax25->sk);
		}
	} else {
		ax25_free_cb(ax25);
	}

	restore_flags(flags);
}

/*
 * dl1bke 960311: set parameters for existing AX.25 connections,
 *		  includes a KILL command to abort any connection.
 *		  VERY useful for debugging ;-)
 */
static int ax25_ctl_ioctl(const unsigned int cmd, void *arg)
{
	struct ax25_ctl_struct ax25_ctl;
	ax25_digi digi;
	ax25_dev *ax25_dev;
	ax25_cb *ax25;
	unsigned int k;

	if (copy_from_user(&ax25_ctl, arg, sizeof(ax25_ctl)))
		return -EFAULT;

	if ((ax25_dev = ax25_addr_ax25dev(&ax25_ctl.port_addr)) == NULL)