pppoe.c

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/** -*- linux-c -*- ***********************************************************
 * Linux PPP over Ethernet (PPPoX/PPPoE) Sockets
 *
 * PPPoX --- Generic PPP encapsulation socket family
 * PPPoE --- PPP over Ethernet (RFC 2516)
 *
 *
 * Version:    0.6.4
 *
 * 030700 :     Fixed connect logic to allow for disconnect.
 * 270700 :	Fixed potential SMP problems; we must protect against 
 *		simultaneous invocation of ppp_input 
 *		and ppp_unregister_channel.
 * 040800 :	Respect reference count mechanisms on net-devices.
 * 200800 :     fix kfree(skb) in pppoe_rcv (acme)
 *		Module reference count is decremented in the right spot now,
 *		guards against sock_put not actually freeing the sk 
 *		in pppoe_release.
 * 051000 :	Initialization cleanup.
 * 111100 :	Fix recvmsg.
 *
 * Author:	Michal Ostrowski <[e-mail]>
 * Contributors:
 * 		Arnaldo Carvalho de Melo <[e-mail]>
 *
 * License:
 *		This program 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.
 *
 */

#include <linux/string.h>
#include <linux/module.h>

#include <asm/uaccess.h>

#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/malloc.h>
#include <linux/errno.h>

#include <linux/netdevice.h>
#include <linux/net.h>
#include <linux/inetdevice.h>
#include <linux/etherdevice.h>
#include <linux/skbuff.h>
#include <linux/init.h>
#include <linux/if_ether.h>
#include <linux/if_pppox.h>
#include <net/sock.h>
#include <linux/ppp_channel.h>
#include <linux/ppp_defs.h>
#include <linux/if_ppp.h>
#include <linux/if_pppvar.h>
#include <linux/notifier.h>
#include <linux/file.h>
#include <linux/proc_fs.h>



static int __attribute__((unused)) pppoe_debug = 7;
#define PPPOE_HASH_BITS 4
#define PPPOE_HASH_SIZE (1<<PPPOE_HASH_BITS)

int pppoe_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg);
int pppoe_xmit(struct ppp_channel *chan, struct sk_buff *skb);
int __pppoe_xmit(struct sock *sk, struct sk_buff *skb);

struct proto_ops pppoe_ops;


#if 0
#define CHECKPTR(x,y) { if (!(x) && pppoe_debug &7 ){ printk(KERN_CRIT "PPPoE Invalid pointer : %s , %p\n",#x,(x)); error=-EINVAL; goto y; }}
#define DEBUG(s,args...) if( pppoe_debug & (s) ) printk(KERN_CRIT args );
#else
#define CHECKPTR(x,y) do {} while (0);
#define DEBUG(s,args...) do { } while (0);
#endif



static rwlock_t pppoe_hash_lock = RW_LOCK_UNLOCKED;


static inline int cmp_2_addr(struct pppoe_addr *a, struct pppoe_addr *b)
{
	return (a->sid == b->sid &&
		(memcmp(a->remote, b->remote, ETH_ALEN) == 0));
}

static inline int cmp_addr(struct pppoe_addr *a, unsigned long sid, char *addr)
{
	return (a->sid == sid &&
		(memcmp(a->remote,addr,ETH_ALEN) == 0));
}

static int hash_item(unsigned long sid, unsigned char *addr)
{
	char hash=0;
	int i,j;
	for (i = 0; i < ETH_ALEN ; ++i){
		for (j = 0; j < 8/PPPOE_HASH_BITS ; ++j){
			hash ^= addr[i] >> ( j * PPPOE_HASH_BITS );
		}
	}

	for (i = 0; i < (sizeof(unsigned long)*8) / PPPOE_HASH_BITS ; ++i)
		hash ^= sid >> (i*PPPOE_HASH_BITS);

	return hash & ( PPPOE_HASH_SIZE - 1 );
}	

static struct pppox_opt *item_hash_table[PPPOE_HASH_SIZE] = { 0, };

/**********************************************************************
 *
 *  Set/get/delete/rehash items  (internal versions)
 *
 **********************************************************************/
static struct pppox_opt *__get_item(unsigned long sid, unsigned char *addr)
{
	int hash = hash_item(sid, addr);
	struct pppox_opt *ret;

	ret = item_hash_table[hash];

	while (ret && !cmp_addr(&ret->pppoe_pa, sid, addr))
		ret = ret->next;

	return ret;
}

static int __set_item(struct pppox_opt *po)
{
	int hash = hash_item(po->pppoe_pa.sid, po->pppoe_pa.remote);
	struct pppox_opt *ret;

	ret = item_hash_table[hash];
	while (ret) {
		if (cmp_2_addr(&ret->pppoe_pa, &po->pppoe_pa))
			return -EALREADY;

		ret = ret->next;
	}

	if (!ret) {
		po->next = item_hash_table[hash];
		item_hash_table[hash] = po;
	}

	return 0;
}

static struct pppox_opt *__delete_item(unsigned long sid, char *addr)
{
	int hash = hash_item(sid, addr);
	struct pppox_opt *ret, **src;

	ret = item_hash_table[hash];
	src = &item_hash_table[hash];

	while (ret) {
		if (cmp_addr(&ret->pppoe_pa, sid, addr)) {
			*src = ret->next;
			break;
		}

		src = &ret->next;
		ret = ret->next;
	}

	return ret;
}

/**********************************************************************
 *
 *  Set/get/delete/rehash items
 *
 **********************************************************************/
static inline struct pppox_opt *get_item(unsigned long sid,
					 unsigned char *addr)
{
	struct pppox_opt *po;

	read_lock_bh(&pppoe_hash_lock);
	po = __get_item(sid, addr);
	if(po)
		sock_hold(po->sk);
	read_unlock_bh(&pppoe_hash_lock);

	return po;
}

static inline struct pppox_opt *get_item_by_addr(struct sockaddr_pppox *sp)
{
	return get_item(sp->sa_addr.pppoe.sid, sp->sa_addr.pppoe.remote);
}

static inline int set_item(struct pppox_opt *po)
{
	int i;

	if (!po)
		return -EINVAL;

	write_lock_bh(&pppoe_hash_lock);
	i = __set_item(po);
	write_unlock_bh(&pppoe_hash_lock);

	return i;
}

static inline struct pppox_opt *delete_item(unsigned long sid, char *addr)
{
	struct pppox_opt *ret;

	write_lock_bh(&pppoe_hash_lock);
	ret = __delete_item(sid, addr);
	write_unlock_bh(&pppoe_hash_lock);

	return ret;
}



/***************************************************************************
 *
 *  Handler for device events.
 *  Certain device events require that sockets be unconnected.
 *
 **************************************************************************/
static int pppoe_device_event(struct notifier_block *this,
			      unsigned long event, void *ptr)
{
	int error = NOTIFY_DONE;
	struct net_device *dev = (struct net_device *) ptr;
	struct pppox_opt *po = NULL;
	int hash = 0;
	
	/* Only look at sockets that are using this specific device. */
	switch (event) {
	case NETDEV_CHANGEMTU:
	    /* A change in mtu is a bad thing, requiring
	     * LCP re-negotiation.
	     */
	case NETDEV_GOING_DOWN:
	case NETDEV_DOWN:

		/* Find every socket on this device and kill it. */
		read_lock_bh(&pppoe_hash_lock);

		while (!po && hash < PPPOE_HASH_SIZE){
			po = item_hash_table[hash];
			++hash;
		}
	
		while (po && hash < PPPOE_HASH_SIZE){
			if(po->pppoe_dev == dev){
				lock_sock(po->sk);
				if (po->sk->state & (PPPOX_CONNECTED|PPPOX_BOUND)){
					pppox_unbind_sock(po->sk);
				
					dev_put(po->pppoe_dev);
					po->pppoe_dev = NULL;

					po->sk->state = PPPOX_DEAD;
					po->sk->state_change(po->sk);
				}
 				release_sock(po->sk);
			}
			if (po->next) {
				po = po->next;
			} else {
				po = NULL;
				while (!po && hash < PPPOE_HASH_SIZE){
					po = item_hash_table[hash];
					++hash;
				}
			}
		}
		read_unlock_bh(&pppoe_hash_lock);
		break;
	default:
		break;
	};

	return error;
}


static struct notifier_block pppoe_notifier = {
	notifier_call: pppoe_device_event,
};




/************************************************************************
 *
 * Do the real work of receiving a PPPoE Session frame.
 *
 ***********************************************************************/
int pppoe_rcv_core(struct sock *sk, struct sk_buff *skb){
	struct pppox_opt  *po=sk->protinfo.pppox;
	struct pppox_opt *relay_po = NULL;

	if (sk->state & PPPOX_BOUND) {
		skb_pull(skb, sizeof(struct pppoe_hdr));
		
		ppp_input(&po->chan, skb);
	} else if( sk->state & PPPOX_RELAY ){

		relay_po = get_item_by_addr( &po->pppoe_relay );

		if( relay_po == NULL  ||
		    !( relay_po->sk->state & PPPOX_CONNECTED ) ){
			goto abort;
		}
		
		skb_pull(skb, sizeof(struct pppoe_hdr));
		if( !__pppoe_xmit( relay_po->sk , skb) ){
			goto abort;
		}
	} else {
		sock_queue_rcv_skb(sk, skb);
	}
	return 1;
abort:
	if(relay_po)
		sock_put(relay_po->sk);
	return 0;

}




/************************************************************************
 *
 * Receive wrapper called in BH context.
 *
 ***********************************************************************/
static int pppoe_rcv(struct sk_buff *skb,
		      struct net_device *dev,
		      struct packet_type *pt)

{
	struct pppoe_hdr *ph = (struct pppoe_hdr *) skb->nh.raw;
	struct pppox_opt *po;
	struct sock *sk ;
	int ret;

	po = get_item((unsigned long) ph->sid, skb->mac.ethernet->h_source);

	if(!po){
		kfree_skb(skb);
		return 0;
	}

	sk = po->sk;
        bh_lock_sock(sk);

	/* Socket state is unknown, must put skb into backlog. */
	if( sk->lock.users != 0 ){
		sk_add_backlog( sk, skb);
		ret = 1;
	}else{
		ret = pppoe_rcv_core(sk, skb);
	}
	
	bh_unlock_sock(sk);
	sock_put(sk);
	return ret;
}


/************************************************************************
 *
 * Receive wrapper called in process context.
 *
 ***********************************************************************/
int pppoe_backlog_rcv(struct sock *sk, struct sk_buff *skb)
{
	lock_sock(sk);
	pppoe_rcv_core(sk, skb);
	release_sock(sk);
	return 0;
}



/************************************************************************
 *
 * Receive a PPPoE Discovery frame.
 * This is solely for detection of PADT frames
 *
 ***********************************************************************/
static int pppoe_disc_rcv(struct sk_buff *skb,
			  struct net_device *dev,
			  struct packet_type *pt)

{
	struct pppoe_hdr *ph = (struct pppoe_hdr *) skb->nh.raw;
	struct pppox_opt *po;
	struct sock *sk = NULL;

	if (ph->code != PADT_CODE)
		goto abort;

	po = get_item((unsigned long) ph->sid, skb->mac.ethernet->h_source);

	if (!po)
		goto abort_put;

	sk = po->sk;

	pppox_unbind_sock(sk);

 abort_put:
	sock_put(sk);
 abort:
	kfree_skb(skb);
	return 0;
}




struct packet_type pppoes_ptype = {
	__constant_htons(ETH_P_PPP_SES),
	NULL,
	pppoe_rcv,
	NULL,
	NULL
};

struct packet_type pppoed_ptype = {
	__constant_htons(ETH_P_PPP_DISC),
	NULL,
	pppoe_disc_rcv,
	NULL,
	NULL
};

/***********************************************************************
 *
 * Really kill the socket. (Called from sock_put if refcnt == 0.)
 *
 **********************************************************************/
void pppoe_sock_destruct(struct sock *sk)
{
	if (sk->protinfo.destruct_hook)
		kfree(sk->protinfo.destruct_hook);
	MOD_DEC_USE_COUNT;
}


/***********************************************************************
 *
 * Initialize a new struct sock.
 *
 **********************************************************************/
static int pppoe_create(struct socket *sock)
{
	int error = 0;
	struct sock *sk;
	
	MOD_INC_USE_COUNT;
	
	sk = sk_alloc(PF_PPPOX, GFP_KERNEL, 1);
	if (!sk)
		return -ENOMEM;

	sock_init_data(sock, sk);

	sock->state = SS_UNCONNECTED;
	sock->ops   = &pppoe_ops;

	sk->protocol = PX_PROTO_OE;
	sk->family = PF_PPPOX;

	sk->backlog_rcv = pppoe_backlog_rcv;
	sk->next = NULL;
	sk->pprev = NULL;
	sk->state = PPPOX_NONE;
	sk->type = SOCK_STREAM;
	sk->destruct = pppoe_sock_destruct;

	sk->protinfo.pppox = kmalloc(sizeof(struct pppox_opt), GFP_KERNEL);
	if (!sk->protinfo.pppox) {
		error = -ENOMEM;
		goto free_sk;
	}

	memset((void *) sk->protinfo.pppox, 0, sizeof(struct pppox_opt));
	sk->protinfo.pppox->sk = sk;

	/* Delete the protinfo when it is time to do so. */
	sk->protinfo.destruct_hook = sk->protinfo.pppox;
	sock->sk = sk;

	return 0;

free_sk:
	sk_free(sk);
	return error;
}

int pppoe_release(struct socket *sock)
{
	struct sock *sk = sock->sk;
	struct pppox_opt *po;
	int error = 0;

	if (!sk)
		return 0;

	if (sk->dead != 0)
		return -EBADF;

	pppox_unbind_sock(sk);