af_econet.c

linux 内核源代码

/*
 *	An implementation of the Acorn Econet and AUN protocols.
 *	Philip Blundell <[e-mail]>
 *
 *	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/module.h>

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/socket.h>
#include <linux/sockios.h>
#include <linux/in.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/if_ether.h>
#include <linux/netdevice.h>
#include <linux/inetdevice.h>
#include <linux/route.h>
#include <linux/inet.h>
#include <linux/etherdevice.h>
#include <linux/if_arp.h>
#include <linux/wireless.h>
#include <linux/skbuff.h>
#include <linux/udp.h>
#include <net/sock.h>
#include <net/inet_common.h>
#include <linux/stat.h>
#include <linux/init.h>
#include <linux/if_ec.h>
#include <net/udp.h>
#include <net/ip.h>
#include <linux/spinlock.h>
#include <linux/rcupdate.h>
#include <linux/bitops.h>
#include <linux/mutex.h>

#include <asm/uaccess.h>
#include <asm/system.h>

static const struct proto_ops econet_ops;
static struct hlist_head econet_sklist;
static DEFINE_RWLOCK(econet_lock);
static DEFINE_MUTEX(econet_mutex);

/* Since there are only 256 possible network numbers (or fewer, depends
   how you count) it makes sense to use a simple lookup table. */
static struct net_device *net2dev_map[256];

#define EC_PORT_IP	0xd2

#ifdef CONFIG_ECONET_AUNUDP
static DEFINE_SPINLOCK(aun_queue_lock);
static struct socket *udpsock;
#define AUN_PORT	0x8000


struct aunhdr
{
	unsigned char code;		/* AUN magic protocol byte */
	unsigned char port;
	unsigned char cb;
	unsigned char pad;
	unsigned long handle;
};

static unsigned long aun_seq;

/* Queue of packets waiting to be transmitted. */
static struct sk_buff_head aun_queue;
static struct timer_list ab_cleanup_timer;

#endif		/* CONFIG_ECONET_AUNUDP */

/* Per-packet information */
struct ec_cb
{
	struct sockaddr_ec sec;
	unsigned long cookie;		/* Supplied by user. */
#ifdef CONFIG_ECONET_AUNUDP
	int done;
	unsigned long seq;		/* Sequencing */
	unsigned long timeout;		/* Timeout */
	unsigned long start;		/* jiffies */
#endif
#ifdef CONFIG_ECONET_NATIVE
	void (*sent)(struct sk_buff *, int result);
#endif
};

static void econet_remove_socket(struct hlist_head *list, struct sock *sk)
{
	write_lock_bh(&econet_lock);
	sk_del_node_init(sk);
	write_unlock_bh(&econet_lock);
}

static void econet_insert_socket(struct hlist_head *list, struct sock *sk)
{
	write_lock_bh(&econet_lock);
	sk_add_node(sk, list);
	write_unlock_bh(&econet_lock);
}

/*
 *	Pull a packet from our receive queue and hand it to the user.
 *	If necessary we block.
 */

static int econet_recvmsg(struct kiocb *iocb, struct socket *sock,
			  struct msghdr *msg, size_t len, int flags)
{
	struct sock *sk = sock->sk;
	struct sk_buff *skb;
	size_t copied;
	int err;

	msg->msg_namelen = sizeof(struct sockaddr_ec);

	mutex_lock(&econet_mutex);

	/*
	 *	Call the generic datagram receiver. This handles all sorts
	 *	of horrible races and re-entrancy so we can forget about it
	 *	in the protocol layers.
	 *
	 *	Now it will return ENETDOWN, if device have just gone down,
	 *	but then it will block.
	 */

	skb=skb_recv_datagram(sk,flags,flags&MSG_DONTWAIT,&err);

	/*
	 *	An error occurred so return it. Because skb_recv_datagram()
	 *	handles the blocking we don't see and worry about blocking
	 *	retries.
	 */

	if(skb==NULL)
		goto out;

	/*
	 *	You lose any data beyond the buffer you gave. If it worries a
	 *	user program they can ask the device for its MTU anyway.
	 */

	copied = skb->len;
	if (copied > len)
	{
		copied=len;
		msg->msg_flags|=MSG_TRUNC;
	}

	/* We can't use skb_copy_datagram here */
	err = memcpy_toiovec(msg->msg_iov, skb->data, copied);
	if (err)
		goto out_free;
	sk->sk_stamp = skb->tstamp;

	if (msg->msg_name)
		memcpy(msg->msg_name, skb->cb, msg->msg_namelen);

	/*
	 *	Free or return the buffer as appropriate. Again this
	 *	hides all the races and re-entrancy issues from us.
	 */
	err = copied;

out_free:
	skb_free_datagram(sk, skb);
out:
	mutex_unlock(&econet_mutex);
	return err;
}

/*
 *	Bind an Econet socket.
 */

static int econet_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
{
	struct sockaddr_ec *sec = (struct sockaddr_ec *)uaddr;
	struct sock *sk;
	struct econet_sock *eo;

	/*
	 *	Check legality
	 */

	if (addr_len < sizeof(struct sockaddr_ec) ||
	    sec->sec_family != AF_ECONET)
		return -EINVAL;

	mutex_lock(&econet_mutex);

	sk = sock->sk;
	eo = ec_sk(sk);

	eo->cb	    = sec->cb;
	eo->port    = sec->port;
	eo->station = sec->addr.station;
	eo->net	    = sec->addr.net;

	mutex_unlock(&econet_mutex);

	return 0;
}

#if defined(CONFIG_ECONET_AUNUDP) || defined(CONFIG_ECONET_NATIVE)
/*
 *	Queue a transmit result for the user to be told about.
 */

static void tx_result(struct sock *sk, unsigned long cookie, int result)
{
	struct sk_buff *skb = alloc_skb(0, GFP_ATOMIC);
	struct ec_cb *eb;
	struct sockaddr_ec *sec;

	if (skb == NULL)
	{
		printk(KERN_DEBUG "ec: memory squeeze, transmit result dropped.\n");
		return;
	}

	eb = (struct ec_cb *)&skb->cb;
	sec = (struct sockaddr_ec *)&eb->sec;
	memset(sec, 0, sizeof(struct sockaddr_ec));
	sec->cookie = cookie;
	sec->type = ECTYPE_TRANSMIT_STATUS | result;
	sec->sec_family = AF_ECONET;

	if (sock_queue_rcv_skb(sk, skb) < 0)
		kfree_skb(skb);
}
#endif

#ifdef CONFIG_ECONET_NATIVE
/*
 *	Called by the Econet hardware driver when a packet transmit
 *	has completed.  Tell the user.
 */

static void ec_tx_done(struct sk_buff *skb, int result)
{
	struct ec_cb *eb = (struct ec_cb *)&skb->cb;
	tx_result(skb->sk, eb->cookie, result);
}
#endif

/*
 *	Send a packet.  We have to work out which device it's going out on
 *	and hence whether to use real Econet or the UDP emulation.
 */

static int econet_sendmsg(struct kiocb *iocb, struct socket *sock,
			  struct msghdr *msg, size_t len)
{
	struct sock *sk = sock->sk;
	struct sockaddr_ec *saddr=(struct sockaddr_ec *)msg->msg_name;
	struct net_device *dev;
	struct ec_addr addr;
	int err;
	unsigned char port, cb;
#if defined(CONFIG_ECONET_AUNUDP) || defined(CONFIG_ECONET_NATIVE)
	struct sk_buff *skb;
	struct ec_cb *eb;
#endif
#ifdef CONFIG_ECONET_AUNUDP
	struct msghdr udpmsg;
	struct iovec iov[msg->msg_iovlen+1];
	struct aunhdr ah;
	struct sockaddr_in udpdest;
	__kernel_size_t size;
	int i;
	mm_segment_t oldfs;
#endif

	/*
	 *	Check the flags.
	 */

	if (msg->msg_flags & ~(MSG_DONTWAIT|MSG_CMSG_COMPAT))
		return -EINVAL;

	/*
	 *	Get and verify the address.
	 */

	mutex_lock(&econet_mutex);

	if (saddr == NULL) {
		struct econet_sock *eo = ec_sk(sk);

		addr.station = eo->station;
		addr.net     = eo->net;
		port	     = eo->port;
		cb	     = eo->cb;
	} else {
		if (msg->msg_namelen < sizeof(struct sockaddr_ec)) {
			mutex_unlock(&econet_mutex);
			return -EINVAL;
		}
		addr.station = saddr->addr.station;
		addr.net = saddr->addr.net;
		port = saddr->port;
		cb = saddr->cb;
	}

	/* Look for a device with the right network number. */
	dev = net2dev_map[addr.net];

	/* If not directly reachable, use some default */
	if (dev == NULL) {
		dev = net2dev_map[0];
		/* No interfaces at all? */
		if (dev == NULL) {
			mutex_unlock(&econet_mutex);
			return -ENETDOWN;
		}
	}

	if (len + 15 > dev->mtu) {
		mutex_unlock(&econet_mutex);
		return -EMSGSIZE;
	}

	if (dev->type == ARPHRD_ECONET) {
		/* Real hardware Econet.  We're not worthy etc. */
#ifdef CONFIG_ECONET_NATIVE
		unsigned short proto = 0;
		int res;

		dev_hold(dev);

		skb = sock_alloc_send_skb(sk, len+LL_RESERVED_SPACE(dev),
					  msg->msg_flags & MSG_DONTWAIT, &err);
		if (skb==NULL)
			goto out_unlock;

		skb_reserve(skb, LL_RESERVED_SPACE(dev));
		skb_reset_network_header(skb);

		eb = (struct ec_cb *)&skb->cb;

		/* BUG: saddr may be NULL */
		eb->cookie = saddr->cookie;
		eb->sec = *saddr;
		eb->sent = ec_tx_done;

		err = -EINVAL;
		res = dev_hard_header(skb, dev, ntohs(proto), &addr, NULL, len);
		if (res < 0)
			goto out_free;
		if (res > 0) {
			struct ec_framehdr *fh;
			/* Poke in our control byte and
			   port number.  Hack, hack.  */
			fh = (struct ec_framehdr *)(skb->data);
			fh->cb = cb;
			fh->port = port;
			if (sock->type != SOCK_DGRAM) {
				skb_reset_tail_pointer(skb);
				skb->len = 0;
			}
		}

		/* Copy the data. Returns -EFAULT on error */
		err = memcpy_fromiovec(skb_put(skb,len), msg->msg_iov, len);
		skb->protocol = proto;
		skb->dev = dev;
		skb->priority = sk->sk_priority;
		if (err)
			goto out_free;

		err = -ENETDOWN;
		if (!(dev->flags & IFF_UP))
			goto out_free;

		/*
		 *	Now send it
		 */

		dev_queue_xmit(skb);
		dev_put(dev);
		mutex_unlock(&econet_mutex);
		return(len);

	out_free:
		kfree_skb(skb);
	out_unlock:
		if (dev)
			dev_put(dev);
#else
		err = -EPROTOTYPE;
#endif
		mutex_unlock(&econet_mutex);

		return err;
	}

#ifdef CONFIG_ECONET_AUNUDP
	/* AUN virtual Econet. */

	if (udpsock == NULL) {
		mutex_unlock(&econet_mutex);
		return -ENETDOWN;		/* No socket - can't send */
	}

	/* Make up a UDP datagram and hand it off to some higher intellect. */

	memset(&udpdest, 0, sizeof(udpdest));
	udpdest.sin_family = AF_INET;
	udpdest.sin_port = htons(AUN_PORT);

	/* At the moment we use the stupid Acorn scheme of Econet address
	   y.x maps to IP a.b.c.x.  This should be replaced with something
	   more flexible and more aware of subnet masks.  */
	{
		struct in_device *idev;
		unsigned long network = 0;

		rcu_read_lock();
		idev = __in_dev_get_rcu(dev);
		if (idev) {
			if (idev->ifa_list)
				network = ntohl(idev->ifa_list->ifa_address) &
					0xffffff00;		/* !!! */
		}
		rcu_read_unlock();
		udpdest.sin_addr.s_addr = htonl(network | addr.station);
	}

	ah.port = port;
	ah.cb = cb & 0x7f;
	ah.code = 2;		/* magic */
	ah.pad = 0;

	/* tack our header on the front of the iovec */
	size = sizeof(struct aunhdr);
	/*
	 * XXX: that is b0rken.  We can't mix userland and kernel pointers
	 * in iovec, since on a lot of platforms copy_from_user() will
	 * *not* work with the kernel and userland ones at the same time,
	 * regardless of what we do with set_fs().  And we are talking about
	 * econet-over-ethernet here, so "it's only ARM anyway" doesn't
	 * apply.  Any suggestions on fixing that code?		-- AV
	 */
	iov[0].iov_base = (void *)&ah;
	iov[0].iov_len = size;
	for (i = 0; i < msg->msg_iovlen; i++) {
		void __user *base = msg->msg_iov[i].iov_base;
		size_t len = msg->msg_iov[i].iov_len;
		/* Check it now since we switch to KERNEL_DS later. */
		if (!access_ok(VERIFY_READ, base, len)) {
			mutex_unlock(&econet_mutex);
			return -EFAULT;
		}
		iov[i+1].iov_base = base;
		iov[i+1].iov_len = len;
		size += len;
	}

	/* Get a skbuff (no data, just holds our cb information) */
	if ((skb = sock_alloc_send_skb(sk, 0,
				       msg->msg_flags & MSG_DONTWAIT,
				       &err)) == NULL) {
		mutex_unlock(&econet_mutex);
		return err;
	}

	eb = (struct ec_cb *)&skb->cb;

	eb->cookie = saddr->cookie;
	eb->timeout = (5*HZ);
	eb->start = jiffies;
	ah.handle = aun_seq;
	eb->seq = (aun_seq++);
	eb->sec = *saddr;

	skb_queue_tail(&aun_queue, skb);

	udpmsg.msg_name = (void *)&udpdest;
	udpmsg.msg_namelen = sizeof(udpdest);
	udpmsg.msg_iov = &iov[0];
	udpmsg.msg_iovlen = msg->msg_iovlen + 1;
	udpmsg.msg_control = NULL;
	udpmsg.msg_controllen = 0;
	udpmsg.msg_flags=0;

	oldfs = get_fs(); set_fs(KERNEL_DS);	/* More privs :-) */
	err = sock_sendmsg(udpsock, &udpmsg, size);
	set_fs(oldfs);
#else
	err = -EPROTOTYPE;
#endif
	mutex_unlock(&econet_mutex);

	return err;
}

/*
 *	Look up the address of a socket.
 */

static int econet_getname(struct socket *sock, struct sockaddr *uaddr,
			  int *uaddr_len, int peer)
{
	struct sock *sk;
	struct econet_sock *eo;
	struct sockaddr_ec *sec = (struct sockaddr_ec *)uaddr;

	if (peer)
		return -EOPNOTSUPP;

	mutex_lock(&econet_mutex);

	sk = sock->sk;
	eo = ec_sk(sk);

	sec->sec_family	  = AF_ECONET;
	sec->port	  = eo->port;
	sec->addr.station = eo->station;
	sec->addr.net	  = eo->net;

	mutex_unlock(&econet_mutex);

	*uaddr_len = sizeof(*sec);
	return 0;
}

static void econet_destroy_timer(unsigned long data)
{
	struct sock *sk=(struct sock *)data;

	if (!atomic_read(&sk->sk_wmem_alloc) &&
	    !atomic_read(&sk->sk_rmem_alloc)) {
		sk_free(sk);
		return;
	}

	sk->sk_timer.expires = jiffies + 10 * HZ;
	add_timer(&sk->sk_timer);
	printk(KERN_DEBUG "econet socket destroy delayed\n");
}

/*
 *	Close an econet socket.
 */

static int econet_release(struct socket *sock)
{
	struct sock *sk;

	mutex_lock(&econet_mutex);

	sk = sock->sk;
	if (!sk)
		goto out_unlock;

	econet_remove_socket(&econet_sklist, sk);

	/*
	 *	Now the socket is dead. No more input will appear.
	 */

	sk->sk_state_change(sk);	/* It is useless. Just for sanity. */

	sock->sk = NULL;
	sk->sk_socket = NULL;
	sock_set_flag(sk, SOCK_DEAD);

	/* Purge queues */

	skb_queue_purge(&sk->sk_receive_queue);

	if (atomic_read(&sk->sk_rmem_alloc) ||
	    atomic_read(&sk->sk_wmem_alloc)) {
		sk->sk_timer.data     = (unsigned long)sk;
		sk->sk_timer.expires  = jiffies + HZ;
		sk->sk_timer.function = econet_destroy_timer;
		add_timer(&sk->sk_timer);

		goto out_unlock;
	}

	sk_free(sk);