br2684.c

linux 内核源代码

/*
Experimental ethernet netdevice using ATM AAL5 as underlying carrier
(RFC1483 obsoleted by RFC2684) for Linux 2.4
Author: Marcell GAL, 2000, XDSL Ltd, Hungary
*/

#include <linux/module.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <linux/etherdevice.h>
#include <linux/rtnetlink.h>
#include <linux/ip.h>
#include <asm/uaccess.h>
#include <net/arp.h>
#include <linux/atm.h>
#include <linux/atmdev.h>
#include <linux/capability.h>
#include <linux/seq_file.h>

#include <linux/atmbr2684.h>

#include "common.h"

#ifdef SKB_DEBUG
static void skb_debug(const struct sk_buff *skb)
{
#define NUM2PRINT 50
	char buf[NUM2PRINT * 3 + 1];	/* 3 chars per byte */
	int i = 0;
	for (i = 0; i < skb->len && i < NUM2PRINT; i++) {
		sprintf(buf + i * 3, "%2.2x ", 0xff & skb->data[i]);
	}
	printk(KERN_DEBUG "br2684: skb: %s\n", buf);
}
#else
#define skb_debug(skb)	do {} while (0)
#endif

static unsigned char llc_oui_pid_pad[] =
    { 0xAA, 0xAA, 0x03, 0x00, 0x80, 0xC2, 0x00, 0x07, 0x00, 0x00 };
#define PADLEN	(2)

enum br2684_encaps {
	e_vc  = BR2684_ENCAPS_VC,
	e_llc = BR2684_ENCAPS_LLC,
};

struct br2684_vcc {
	struct atm_vcc  *atmvcc;
	struct net_device *device;
	/* keep old push,pop functions for chaining */
	void (*old_push)(struct atm_vcc *vcc,struct sk_buff *skb);
	/* void (*old_pop)(struct atm_vcc *vcc,struct sk_buff *skb); */
	enum br2684_encaps encaps;
	struct list_head brvccs;
#ifdef CONFIG_ATM_BR2684_IPFILTER
	struct br2684_filter filter;
#endif /* CONFIG_ATM_BR2684_IPFILTER */
	unsigned copies_needed, copies_failed;
};

struct br2684_dev {
	struct net_device *net_dev;
	struct list_head br2684_devs;
	int number;
	struct list_head brvccs; /* one device <=> one vcc (before xmas) */
	struct net_device_stats stats;
	int mac_was_set;
};

/*
 * This lock should be held for writing any time the list of devices or
 * their attached vcc's could be altered.  It should be held for reading
 * any time these are being queried.  Note that we sometimes need to
 * do read-locking under interrupt context, so write locking must block
 * the current CPU's interrupts
 */
static DEFINE_RWLOCK(devs_lock);

static LIST_HEAD(br2684_devs);

static inline struct br2684_dev *BRPRIV(const struct net_device *net_dev)
{
	return (struct br2684_dev *) net_dev->priv;
}

static inline struct net_device *list_entry_brdev(const struct list_head *le)
{
	return list_entry(le, struct br2684_dev, br2684_devs)->net_dev;
}

static inline struct br2684_vcc *BR2684_VCC(const struct atm_vcc *atmvcc)
{
	return (struct br2684_vcc *) (atmvcc->user_back);
}

static inline struct br2684_vcc *list_entry_brvcc(const struct list_head *le)
{
	return list_entry(le, struct br2684_vcc, brvccs);
}

/* Caller should hold read_lock(&devs_lock) */
static struct net_device *br2684_find_dev(const struct br2684_if_spec *s)
{
	struct list_head *lh;
	struct net_device *net_dev;
	switch (s->method) {
	case BR2684_FIND_BYNUM:
		list_for_each(lh, &br2684_devs) {
			net_dev = list_entry_brdev(lh);
			if (BRPRIV(net_dev)->number == s->spec.devnum)
				return net_dev;
		}
		break;
	case BR2684_FIND_BYIFNAME:
		list_for_each(lh, &br2684_devs) {
			net_dev = list_entry_brdev(lh);
			if (!strncmp(net_dev->name, s->spec.ifname, IFNAMSIZ))
				return net_dev;
		}
		break;
	}
	return NULL;
}

/*
 * Send a packet out a particular vcc.  Not to useful right now, but paves
 * the way for multiple vcc's per itf.  Returns true if we can send,
 * otherwise false
 */
static int br2684_xmit_vcc(struct sk_buff *skb, struct br2684_dev *brdev,
	struct br2684_vcc *brvcc)
{
	struct atm_vcc *atmvcc;
	int minheadroom = (brvcc->encaps == e_llc) ? 10 : 2;
	if (skb_headroom(skb) < minheadroom) {
		struct sk_buff *skb2 = skb_realloc_headroom(skb, minheadroom);
		brvcc->copies_needed++;
		dev_kfree_skb(skb);
		if (skb2 == NULL) {
			brvcc->copies_failed++;
			return 0;
		}
		skb = skb2;
	}
	skb_push(skb, minheadroom);
	if (brvcc->encaps == e_llc)
		skb_copy_to_linear_data(skb, llc_oui_pid_pad, 10);
	else
		memset(skb->data, 0, 2);
	skb_debug(skb);

	ATM_SKB(skb)->vcc = atmvcc = brvcc->atmvcc;
	pr_debug("atm_skb(%p)->vcc(%p)->dev(%p)\n", skb, atmvcc, atmvcc->dev);
	if (!atm_may_send(atmvcc, skb->truesize)) {
		/* we free this here for now, because we cannot know in a higher
			layer whether the skb point it supplied wasn't freed yet.
			now, it always is.
		*/
		dev_kfree_skb(skb);
		return 0;
		}
	atomic_add(skb->truesize, &sk_atm(atmvcc)->sk_wmem_alloc);
	ATM_SKB(skb)->atm_options = atmvcc->atm_options;
	brdev->stats.tx_packets++;
	brdev->stats.tx_bytes += skb->len;
	atmvcc->send(atmvcc, skb);
	return 1;
}

static inline struct br2684_vcc *pick_outgoing_vcc(struct sk_buff *skb,
	struct br2684_dev *brdev)
{
	return list_empty(&brdev->brvccs) ? NULL :
	    list_entry_brvcc(brdev->brvccs.next); /* 1 vcc/dev right now */
}

static int br2684_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
	struct br2684_dev *brdev = BRPRIV(dev);
	struct br2684_vcc *brvcc;

	pr_debug("br2684_start_xmit, skb->dst=%p\n", skb->dst);
	read_lock(&devs_lock);
	brvcc = pick_outgoing_vcc(skb, brdev);
	if (brvcc == NULL) {
		pr_debug("no vcc attached to dev %s\n", dev->name);
		brdev->stats.tx_errors++;
		brdev->stats.tx_carrier_errors++;
		/* netif_stop_queue(dev); */
		dev_kfree_skb(skb);
		read_unlock(&devs_lock);
		return 0;
	}
	if (!br2684_xmit_vcc(skb, brdev, brvcc)) {
		/*
		 * We should probably use netif_*_queue() here, but that
		 * involves added complication.  We need to walk before
		 * we can run
		 */
		/* don't free here! this pointer might be no longer valid!
		dev_kfree_skb(skb);
		*/
		brdev->stats.tx_errors++;
		brdev->stats.tx_fifo_errors++;
	}
	read_unlock(&devs_lock);
	return 0;
}

static struct net_device_stats *br2684_get_stats(struct net_device *dev)
{
	pr_debug("br2684_get_stats\n");
	return &BRPRIV(dev)->stats;
}


/*
 * We remember when the MAC gets set, so we don't override it later with
 * the ESI of the ATM card of the first VC
 */
static int (*my_eth_mac_addr)(struct net_device *, void *);
static int br2684_mac_addr(struct net_device *dev, void *p)
{
	int err = my_eth_mac_addr(dev, p);
	if (!err)
		BRPRIV(dev)->mac_was_set = 1;
	return err;
}

#ifdef CONFIG_ATM_BR2684_IPFILTER
/* this IOCTL is experimental. */
static int br2684_setfilt(struct atm_vcc *atmvcc, void __user *arg)
{
	struct br2684_vcc *brvcc;
	struct br2684_filter_set fs;

	if (copy_from_user(&fs, arg, sizeof fs))
		return -EFAULT;
	if (fs.ifspec.method != BR2684_FIND_BYNOTHING) {
		/*
		 * This is really a per-vcc thing, but we can also search
		 * by device
		 */
		struct br2684_dev *brdev;
		read_lock(&devs_lock);
		brdev = BRPRIV(br2684_find_dev(&fs.ifspec));
		if (brdev == NULL || list_empty(&brdev->brvccs) ||
		    brdev->brvccs.next != brdev->brvccs.prev)  /* >1 VCC */
			brvcc = NULL;
		else
			brvcc = list_entry_brvcc(brdev->brvccs.next);
		read_unlock(&devs_lock);
		if (brvcc == NULL)
			return -ESRCH;
	} else
		brvcc = BR2684_VCC(atmvcc);
	memcpy(&brvcc->filter, &fs.filter, sizeof(brvcc->filter));
	return 0;
}

/* Returns 1 if packet should be dropped */
static inline int
packet_fails_filter(__be16 type, struct br2684_vcc *brvcc, struct sk_buff *skb)
{
	if (brvcc->filter.netmask == 0)
		return 0;			/* no filter in place */
	if (type == htons(ETH_P_IP) &&
	    (((struct iphdr *) (skb->data))->daddr & brvcc->filter.
	     netmask) == brvcc->filter.prefix)
		return 0;
	if (type == htons(ETH_P_ARP))
		return 0;
	/* TODO: we should probably filter ARPs too.. don't want to have
	 *   them returning values that don't make sense, or is that ok?
	 */
	return 1;		/* drop */
}
#endif /* CONFIG_ATM_BR2684_IPFILTER */

static void br2684_close_vcc(struct br2684_vcc *brvcc)
{
	pr_debug("removing VCC %p from dev %p\n", brvcc, brvcc->device);
	write_lock_irq(&devs_lock);
	list_del(&brvcc->brvccs);
	write_unlock_irq(&devs_lock);
	brvcc->atmvcc->user_back = NULL;	/* what about vcc->recvq ??? */
	brvcc->old_push(brvcc->atmvcc, NULL);	/* pass on the bad news */
	kfree(brvcc);
	module_put(THIS_MODULE);
}

/* when AAL5 PDU comes in: */
static void br2684_push(struct atm_vcc *atmvcc, struct sk_buff *skb)
{
	struct br2684_vcc *brvcc = BR2684_VCC(atmvcc);
	struct net_device *net_dev = brvcc->device;
	struct br2684_dev *brdev = BRPRIV(net_dev);
	int plen = sizeof(llc_oui_pid_pad) + ETH_HLEN;

	pr_debug("br2684_push\n");

	if (unlikely(skb == NULL)) {
		/* skb==NULL means VCC is being destroyed */
		br2684_close_vcc(brvcc);
		if (list_empty(&brdev->brvccs)) {
			read_lock(&devs_lock);
			list_del(&brdev->br2684_devs);
			read_unlock(&devs_lock);
			unregister_netdev(net_dev);
			free_netdev(net_dev);
		}
		return;
	}

	skb_debug(skb);
	atm_return(atmvcc, skb->truesize);
	pr_debug("skb from brdev %p\n", brdev);
	if (brvcc->encaps == e_llc) {
		/* let us waste some time for checking the encapsulation.
		   Note, that only 7 char is checked so frames with a valid FCS
		   are also accepted (but FCS is not checked of course) */
		if (memcmp(skb->data, llc_oui_pid_pad, 7)) {
			brdev->stats.rx_errors++;
			dev_kfree_skb(skb);
			return;
		}

		/* Strip FCS if present */
		if (skb->len > 7 && skb->data[7] == 0x01)
			__skb_trim(skb, skb->len - 4);
	} else {
		plen = PADLEN + ETH_HLEN;	/* pad, dstmac,srcmac, ethtype */
		/* first 2 chars should be 0 */
		if (*((u16 *) (skb->data)) != 0) {
			brdev->stats.rx_errors++;
			dev_kfree_skb(skb);
			return;
		}
	}
	if (skb->len < plen) {
		brdev->stats.rx_errors++;
		dev_kfree_skb(skb);	/* dev_ not needed? */