dev_mcast.c

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/*
 *	Linux NET3:	Multicast List maintenance. 
 *
 *	Authors:
 *		Tim Kordas <[e-mail]> 
 *		Richard Underwood <[e-mail]>
 *
 *	Stir fried together from the IP multicast and CAP patches above
 *		Alan Cox <[e-mail]>	
 *
 *	Fixes:
 *		Alan Cox	:	Update the device on a real delete
 *					rather than any time but...
 *		Alan Cox	:	IFF_ALLMULTI support.
 *		Alan Cox	: 	New format set_multicast_list() calls.
 *		Gleb Natapov    :       Remove dev_mc_lock.
 *
 *	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/config.h> 
#include <asm/uaccess.h>
#include <asm/system.h>
#include <asm/bitops.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/sched.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/inet.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/proc_fs.h>
#include <linux/init.h>
#include <net/ip.h>
#include <net/route.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <net/arp.h>


/*
 *	Device multicast list maintenance. 
 *
 *	This is used both by IP and by the user level maintenance functions. 
 *	Unlike BSD we maintain a usage count on a given multicast address so 
 *	that a casual user application can add/delete multicasts used by 
 *	protocols without doing damage to the protocols when it deletes the
 *	entries. It also helps IP as it tracks overlapping maps.
 *
 *	Device mc lists are changed by bh at least if IPv6 is enabled,
 *	so that it must be bh protected.
 *
 *	We block accesses to device mc filters with dev->xmit_lock.
 */

/*
 *	Update the multicast list into the physical NIC controller.
 */
 
static void __dev_mc_upload(struct net_device *dev)
{
	/* Don't do anything till we up the interface
	 * [dev_open will call this function so the list will
	 * stay sane]
	 */

	if (!(dev->flags&IFF_UP))
		return;

	/*
	 *	Devices with no set multicast or which have been
	 *	detached don't get set.
	 */

	if (dev->set_multicast_list == NULL ||
	    !netif_device_present(dev))
		return;

	dev->set_multicast_list(dev);
}

void dev_mc_upload(struct net_device *dev)
{
	spin_lock_bh(&dev->xmit_lock);
	__dev_mc_upload(dev);
	spin_unlock_bh(&dev->xmit_lock);
}

/*
 *	Delete a device level multicast
 */
 
int dev_mc_delete(struct net_device *dev, void *addr, int alen, int glbl)
{
	int err = 0;
	struct dev_mc_list *dmi, **dmip;

	spin_lock_bh(&dev->xmit_lock);

	for (dmip = &dev->mc_list; (dmi = *dmip) != NULL; dmip = &dmi->next) {
		/*
		 *	Find the entry we want to delete. The device could
		 *	have variable length entries so check these too.
		 */
		if (memcmp(dmi->dmi_addr, addr, dmi->dmi_addrlen) == 0 &&
		    alen == dmi->dmi_addrlen) {
			if (glbl) {
				int old_glbl = dmi->dmi_gusers;
				dmi->dmi_gusers = 0;
				if (old_glbl == 0)
					break;
			}
			if (--dmi->dmi_users)
				goto done;

			/*
			 *	Last user. So delete the entry.
			 */
			*dmip = dmi->next;
			dev->mc_count--;

			kfree(dmi);

			/*
			 *	We have altered the list, so the card
			 *	loaded filter is now wrong. Fix it
			 */
			__dev_mc_upload(dev);
			
			spin_unlock_bh(&dev->xmit_lock);
			return 0;
		}
	}
	err = -ENOENT;
done:
	spin_unlock_bh(&dev->xmit_lock);
	return err;
}

/*
 *	Add a device level multicast
 */
 
int dev_mc_add(struct net_device *dev, void *addr, int alen, int glbl)
{
	int err = 0;
	struct dev_mc_list *dmi, *dmi1;

	dmi1 = (struct dev_mc_list *)kmalloc(sizeof(*dmi), GFP_ATOMIC);

	spin_lock_bh(&dev->xmit_lock);
	for (dmi = dev->mc_list; dmi != NULL; dmi = dmi->next) {
		if (memcmp(dmi->dmi_addr, addr, dmi->dmi_addrlen) == 0 &&
		    dmi->dmi_addrlen == alen) {
			if (glbl) {
				int old_glbl = dmi->dmi_gusers;
				dmi->dmi_gusers = 1;
				if (old_glbl)
					goto done;
			}
			dmi->dmi_users++;
			goto done;
		}
	}

	if ((dmi = dmi1) == NULL) {
		spin_unlock_bh(&dev->xmit_lock);
		return -ENOMEM;
	}
	memcpy(dmi->dmi_addr, addr, alen);
	dmi->dmi_addrlen = alen;
	dmi->next = dev->mc_list;
	dmi->dmi_users = 1;
	dmi->dmi_gusers = glbl ? 1 : 0;
	dev->mc_list = dmi;
	dev->mc_count++;

	__dev_mc_upload(dev);
	
	spin_unlock_bh(&dev->xmit_lock);
	return 0;

done:
	spin_unlock_bh(&dev->xmit_lock);
	if (dmi1)
		kfree(dmi1);
	return err;
}

/*
 *	Discard multicast list when a device is downed
 */

void dev_mc_discard(struct net_device *dev)
{
	spin_lock_bh(&dev->xmit_lock);
	
	while (dev->mc_list != NULL) {
		struct dev_mc_list *tmp = dev->mc_list;
		dev->mc_list = tmp->next;
		if (tmp->dmi_users > tmp->dmi_gusers)
			printk("dev_mc_discard: multicast leakage! dmi_users=%d\n", tmp->dmi_users);
		kfree(tmp);
	}
	dev->mc_count = 0;

	spin_unlock_bh(&dev->xmit_lock);
}

#ifdef CONFIG_PROC_FS
static int dev_mc_read_proc(char *buffer, char **start, off_t offset,
			    int length, int *eof, void *data)
{
	off_t pos = 0, begin = 0;
	struct dev_mc_list *m;
	int len = 0;
	struct net_device *dev;

	read_lock(&dev_base_lock);
	for (dev = dev_base; dev; dev = dev->next) {
		spin_lock_bh(&dev->xmit_lock);
		for (m = dev->mc_list; m; m = m->next) {
			int i;

			len += sprintf(buffer+len,"%-4d %-15s %-5d %-5d ", dev->ifindex,
				       dev->name, m->dmi_users, m->dmi_gusers);

			for (i = 0; i < m->dmi_addrlen; i++)
				len += sprintf(buffer+len, "%02x", m->dmi_addr[i]);

			len += sprintf(buffer+len, "\n");

			pos = begin + len;
			if (pos < offset) {
				len = 0;
				begin = pos;
			}
			if (pos > offset + length) {
				spin_unlock_bh(&dev->xmit_lock);
				goto done;
			}
		}
		spin_unlock_bh(&dev->xmit_lock);
	}
	*eof = 1;

done:
	read_unlock(&dev_base_lock);
	*start = buffer + (offset - begin);
	len -= (offset - begin);
	if (len > length)
		len = length;
	if (len < 0)
		len = 0;
	return len;
}
#endif

void __init dev_mcast_init(void)
{
#ifdef CONFIG_PROC_FS
	create_proc_read_entry("net/dev_mcast", 0, 0, dev_mc_read_proc, NULL);
#endif
}