clip.c

linux 内核源代码

/* net/atm/clip.c - RFC1577 Classical IP over ATM */

/* Written 1995-2000 by Werner Almesberger, EPFL LRC/ICA */

#include <linux/string.h>
#include <linux/errno.h>
#include <linux/kernel.h> /* for UINT_MAX */
#include <linux/module.h>
#include <linux/init.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <linux/wait.h>
#include <linux/timer.h>
#include <linux/if_arp.h> /* for some manifest constants */
#include <linux/notifier.h>
#include <linux/atm.h>
#include <linux/atmdev.h>
#include <linux/atmclip.h>
#include <linux/atmarp.h>
#include <linux/capability.h>
#include <linux/ip.h> /* for net/route.h */
#include <linux/in.h> /* for struct sockaddr_in */
#include <linux/if.h> /* for IFF_UP */
#include <linux/inetdevice.h>
#include <linux/bitops.h>
#include <linux/poison.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/rcupdate.h>
#include <linux/jhash.h>
#include <net/route.h> /* for struct rtable and routing */
#include <net/icmp.h> /* icmp_send */
#include <asm/param.h> /* for HZ */
#include <asm/byteorder.h> /* for htons etc. */
#include <asm/system.h> /* save/restore_flags */
#include <asm/uaccess.h>
#include <asm/atomic.h>

#include "common.h"
#include "resources.h"
#include <net/atmclip.h>

static struct net_device *clip_devs;
static struct atm_vcc *atmarpd;
static struct neigh_table clip_tbl;
static struct timer_list idle_timer;

static int to_atmarpd(enum atmarp_ctrl_type type, int itf, __be32 ip)
{
	struct sock *sk;
	struct atmarp_ctrl *ctrl;
	struct sk_buff *skb;

	pr_debug("to_atmarpd(%d)\n", type);
	if (!atmarpd)
		return -EUNATCH;
	skb = alloc_skb(sizeof(struct atmarp_ctrl),GFP_ATOMIC);
	if (!skb)
		return -ENOMEM;
	ctrl = (struct atmarp_ctrl *) skb_put(skb,sizeof(struct atmarp_ctrl));
	ctrl->type = type;
	ctrl->itf_num = itf;
	ctrl->ip = ip;
	atm_force_charge(atmarpd, skb->truesize);

	sk = sk_atm(atmarpd);
	skb_queue_tail(&sk->sk_receive_queue, skb);
	sk->sk_data_ready(sk, skb->len);
	return 0;
}

static void link_vcc(struct clip_vcc *clip_vcc, struct atmarp_entry *entry)
{
	pr_debug("link_vcc %p to entry %p (neigh %p)\n", clip_vcc, entry,
		entry->neigh);
	clip_vcc->entry = entry;
	clip_vcc->xoff = 0;	/* @@@ may overrun buffer by one packet */
	clip_vcc->next = entry->vccs;
	entry->vccs = clip_vcc;
	entry->neigh->used = jiffies;
}

static void unlink_clip_vcc(struct clip_vcc *clip_vcc)
{
	struct atmarp_entry *entry = clip_vcc->entry;
	struct clip_vcc **walk;

	if (!entry) {
		printk(KERN_CRIT "!clip_vcc->entry (clip_vcc %p)\n", clip_vcc);
		return;
	}
	netif_tx_lock_bh(entry->neigh->dev);	/* block clip_start_xmit() */
	entry->neigh->used = jiffies;
	for (walk = &entry->vccs; *walk; walk = &(*walk)->next)
		if (*walk == clip_vcc) {
			int error;

			*walk = clip_vcc->next;	/* atomic */
			clip_vcc->entry = NULL;
			if (clip_vcc->xoff)
				netif_wake_queue(entry->neigh->dev);
			if (entry->vccs)
				goto out;
			entry->expires = jiffies - 1;
			/* force resolution or expiration */
			error = neigh_update(entry->neigh, NULL, NUD_NONE,
					     NEIGH_UPDATE_F_ADMIN);
			if (error)
				printk(KERN_CRIT "unlink_clip_vcc: "
				       "neigh_update failed with %d\n", error);
			goto out;
		}
	printk(KERN_CRIT "ATMARP: unlink_clip_vcc failed (entry %p, vcc "
	       "0x%p)\n", entry, clip_vcc);
      out:
	netif_tx_unlock_bh(entry->neigh->dev);
}

/* The neighbour entry n->lock is held. */
static int neigh_check_cb(struct neighbour *n)
{
	struct atmarp_entry *entry = NEIGH2ENTRY(n);
	struct clip_vcc *cv;

	for (cv = entry->vccs; cv; cv = cv->next) {
		unsigned long exp = cv->last_use + cv->idle_timeout;

		if (cv->idle_timeout && time_after(jiffies, exp)) {
			pr_debug("releasing vcc %p->%p of entry %p\n",
				cv, cv->vcc, entry);
			vcc_release_async(cv->vcc, -ETIMEDOUT);
		}
	}

	if (entry->vccs || time_before(jiffies, entry->expires))
		return 0;

	if (atomic_read(&n->refcnt) > 1) {
		struct sk_buff *skb;

		pr_debug("destruction postponed with ref %d\n",
			atomic_read(&n->refcnt));

		while ((skb = skb_dequeue(&n->arp_queue)) != NULL)
			dev_kfree_skb(skb);

		return 0;
	}

	pr_debug("expired neigh %p\n", n);
	return 1;
}

static void idle_timer_check(unsigned long dummy)
{
	write_lock(&clip_tbl.lock);
	__neigh_for_each_release(&clip_tbl, neigh_check_cb);
	mod_timer(&idle_timer, jiffies + CLIP_CHECK_INTERVAL * HZ);
	write_unlock(&clip_tbl.lock);
}

static int clip_arp_rcv(struct sk_buff *skb)
{
	struct atm_vcc *vcc;

	pr_debug("clip_arp_rcv\n");
	vcc = ATM_SKB(skb)->vcc;
	if (!vcc || !atm_charge(vcc, skb->truesize)) {
		dev_kfree_skb_any(skb);
		return 0;
	}
	pr_debug("pushing to %p\n", vcc);
	pr_debug("using %p\n", CLIP_VCC(vcc)->old_push);
	CLIP_VCC(vcc)->old_push(vcc, skb);
	return 0;
}

static const unsigned char llc_oui[] = {
	0xaa,	/* DSAP: non-ISO */
	0xaa,	/* SSAP: non-ISO */
	0x03,	/* Ctrl: Unnumbered Information Command PDU */
	0x00,	/* OUI: EtherType */
	0x00,
	0x00
};

static void clip_push(struct atm_vcc *vcc, struct sk_buff *skb)
{
	struct clip_vcc *clip_vcc = CLIP_VCC(vcc);

	pr_debug("clip push\n");
	if (!skb) {
		pr_debug("removing VCC %p\n", clip_vcc);
		if (clip_vcc->entry)
			unlink_clip_vcc(clip_vcc);
		clip_vcc->old_push(vcc, NULL);	/* pass on the bad news */
		kfree(clip_vcc);
		return;
	}
	atm_return(vcc, skb->truesize);
	skb->dev = clip_vcc->entry ? clip_vcc->entry->neigh->dev : clip_devs;
	/* clip_vcc->entry == NULL if we don't have an IP address yet */
	if (!skb->dev) {
		dev_kfree_skb_any(skb);
		return;
	}
	ATM_SKB(skb)->vcc = vcc;
	skb_reset_mac_header(skb);
	if (!clip_vcc->encap
	    || skb->len < RFC1483LLC_LEN
	    || memcmp(skb->data, llc_oui, sizeof (llc_oui)))
		skb->protocol = htons(ETH_P_IP);
	else {
		skb->protocol = ((__be16 *) skb->data)[3];
		skb_pull(skb, RFC1483LLC_LEN);
		if (skb->protocol == htons(ETH_P_ARP)) {
			PRIV(skb->dev)->stats.rx_packets++;
			PRIV(skb->dev)->stats.rx_bytes += skb->len;
			clip_arp_rcv(skb);
			return;
		}
	}
	clip_vcc->last_use = jiffies;
	PRIV(skb->dev)->stats.rx_packets++;
	PRIV(skb->dev)->stats.rx_bytes += skb->len;
	memset(ATM_SKB(skb), 0, sizeof(struct atm_skb_data));
	netif_rx(skb);
}

/*
 * Note: these spinlocks _must_not_ block on non-SMP. The only goal is that
 * clip_pop is atomic with respect to the critical section in clip_start_xmit.
 */

static void clip_pop(struct atm_vcc *vcc, struct sk_buff *skb)
{
	struct clip_vcc *clip_vcc = CLIP_VCC(vcc);
	struct net_device *dev = skb->dev;
	int old;
	unsigned long flags;

	pr_debug("clip_pop(vcc %p)\n", vcc);
	clip_vcc->old_pop(vcc, skb);
	/* skb->dev == NULL in outbound ARP packets */
	if (!dev)
		return;
	spin_lock_irqsave(&PRIV(dev)->xoff_lock, flags);
	if (atm_may_send(vcc, 0)) {
		old = xchg(&clip_vcc->xoff, 0);
		if (old)
			netif_wake_queue(dev);
	}
	spin_unlock_irqrestore(&PRIV(dev)->xoff_lock, flags);
}

static void clip_neigh_solicit(struct neighbour *neigh, struct sk_buff *skb)
{
	pr_debug("clip_neigh_solicit (neigh %p, skb %p)\n", neigh, skb);
	to_atmarpd(act_need, PRIV(neigh->dev)->number, NEIGH2ENTRY(neigh)->ip);
}

static void clip_neigh_error(struct neighbour *neigh, struct sk_buff *skb)
{
#ifndef CONFIG_ATM_CLIP_NO_ICMP
	icmp_send(skb, ICMP_DEST_UNREACH, ICMP_HOST_UNREACH, 0);
#endif
	kfree_skb(skb);
}

static struct neigh_ops clip_neigh_ops = {
	.family =		AF_INET,
	.solicit =		clip_neigh_solicit,
	.error_report =		clip_neigh_error,
	.output =		dev_queue_xmit,
	.connected_output =	dev_queue_xmit,
	.hh_output =		dev_queue_xmit,
	.queue_xmit =		dev_queue_xmit,
};

static int clip_constructor(struct neighbour *neigh)
{
	struct atmarp_entry *entry = NEIGH2ENTRY(neigh);
	struct net_device *dev = neigh->dev;
	struct in_device *in_dev;
	struct neigh_parms *parms;

	pr_debug("clip_constructor (neigh %p, entry %p)\n", neigh, entry);
	neigh->type = inet_addr_type(entry->ip);
	if (neigh->type != RTN_UNICAST)
		return -EINVAL;

	rcu_read_lock();
	in_dev = __in_dev_get_rcu(dev);
	if (!in_dev) {
		rcu_read_unlock();
		return -EINVAL;
	}

	parms = in_dev->arp_parms;
	__neigh_parms_put(neigh->parms);
	neigh->parms = neigh_parms_clone(parms);
	rcu_read_unlock();

	neigh->ops = &clip_neigh_ops;
	neigh->output = neigh->nud_state & NUD_VALID ?
	    neigh->ops->connected_output : neigh->ops->output;
	entry->neigh = neigh;
	entry->vccs = NULL;
	entry->expires = jiffies - 1;
	return 0;
}

static u32 clip_hash(const void *pkey, const struct net_device *dev)
{
	return jhash_2words(*(u32 *) pkey, dev->ifindex, clip_tbl.hash_rnd);
}

static struct neigh_table clip_tbl = {
	.family 	= AF_INET,
	.entry_size 	= sizeof(struct neighbour)+sizeof(struct atmarp_entry),
	.key_len 	= 4,
	.hash 		= clip_hash,
	.constructor 	= clip_constructor,
	.id 		= "clip_arp_cache",

	/* parameters are copied from ARP ... */
	.parms = {
		.tbl 			= &clip_tbl,
		.base_reachable_time 	= 30 * HZ,
		.retrans_time 		= 1 * HZ,
		.gc_staletime 		= 60 * HZ,
		.reachable_time 	= 30 * HZ,
		.delay_probe_time 	= 5 * HZ,
		.queue_len 		= 3,
		.ucast_probes 		= 3,
		.mcast_probes 		= 3,
		.anycast_delay 		= 1 * HZ,
		.proxy_delay 		= (8 * HZ) / 10,
		.proxy_qlen 		= 64,
		.locktime 		= 1 * HZ,
	},
	.gc_interval 	= 30 * HZ,
	.gc_thresh1 	= 128,
	.gc_thresh2 	= 512,
	.gc_thresh3 	= 1024,
};

/* @@@ copy bh locking from arp.c -- need to bh-enable atm code before */

/*
 * We play with the resolve flag: 0 and 1 have the usual meaning, but -1 means
 * to allocate the neighbour entry but not to ask atmarpd for resolution. Also,
 * don't increment the usage count. This is used to create entries in
 * clip_setentry.
 */

static int clip_encap(struct atm_vcc *vcc, int mode)
{
	CLIP_VCC(vcc)->encap = mode;
	return 0;
}

static int clip_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
	struct clip_priv *clip_priv = PRIV(dev);
	struct atmarp_entry *entry;
	struct atm_vcc *vcc;
	int old;
	unsigned long flags;

	pr_debug("clip_start_xmit (skb %p)\n", skb);
	if (!skb->dst) {
		printk(KERN_ERR "clip_start_xmit: skb->dst == NULL\n");
		dev_kfree_skb(skb);
		clip_priv->stats.tx_dropped++;
		return 0;
	}
	if (!skb->dst->neighbour) {
#if 0
		skb->dst->neighbour = clip_find_neighbour(skb->dst, 1);
		if (!skb->dst->neighbour) {
			dev_kfree_skb(skb);	/* lost that one */
			clip_priv->stats.tx_dropped++;
			return 0;
		}
#endif
		printk(KERN_ERR "clip_start_xmit: NO NEIGHBOUR !\n");
		dev_kfree_skb(skb);
		clip_priv->stats.tx_dropped++;
		return 0;
	}
	entry = NEIGH2ENTRY(skb->dst->neighbour);
	if (!entry->vccs) {
		if (time_after(jiffies, entry->expires)) {
			/* should be resolved */
			entry->expires = jiffies + ATMARP_RETRY_DELAY * HZ;
			to_atmarpd(act_need, PRIV(dev)->number, entry->ip);
		}
		if (entry->neigh->arp_queue.qlen < ATMARP_MAX_UNRES_PACKETS)
			skb_queue_tail(&entry->neigh->arp_queue, skb);
		else {
			dev_kfree_skb(skb);
			clip_priv->stats.tx_dropped++;
		}
		return 0;
	}
	pr_debug("neigh %p, vccs %p\n", entry, entry->vccs);
	ATM_SKB(skb)->vcc = vcc = entry->vccs->vcc;
	pr_debug("using neighbour %p, vcc %p\n", skb->dst->neighbour, vcc);
	if (entry->vccs->encap) {
		void *here;

		here = skb_push(skb, RFC1483LLC_LEN);
		memcpy(here, llc_oui, sizeof(llc_oui));
		((__be16 *) here)[3] = skb->protocol;
	}
	atomic_add(skb->truesize, &sk_atm(vcc)->sk_wmem_alloc);
	ATM_SKB(skb)->atm_options = vcc->atm_options;
	entry->vccs->last_use = jiffies;
	pr_debug("atm_skb(%p)->vcc(%p)->dev(%p)\n", skb, vcc, vcc->dev);
	old = xchg(&entry->vccs->xoff, 1);	/* assume XOFF ... */
	if (old) {
		printk(KERN_WARNING "clip_start_xmit: XOFF->XOFF transition\n");
		return 0;
	}
	clip_priv->stats.tx_packets++;
	clip_priv->stats.tx_bytes += skb->len;
	vcc->send(vcc, skb);
	if (atm_may_send(vcc, 0)) {
		entry->vccs->xoff = 0;
		return 0;
	}
	spin_lock_irqsave(&clip_priv->xoff_lock, flags);
	netif_stop_queue(dev);	/* XOFF -> throttle immediately */
	barrier();
	if (!entry->vccs->xoff)
		netif_start_queue(dev);
	/* Oh, we just raced with clip_pop. netif_start_queue should be
	   good enough, because nothing should really be asleep because
	   of the brief netif_stop_queue. If this isn't true or if it
	   changes, use netif_wake_queue instead. */
	spin_unlock_irqrestore(&clip_priv->xoff_lock, flags);
	return 0;
}

static struct net_device_stats *clip_get_stats(struct net_device *dev)
{
	return &PRIV(dev)->stats;
}

static int clip_mkip(struct atm_vcc *vcc, int timeout)
{
	struct clip_vcc *clip_vcc;
	struct sk_buff *skb;
	struct sk_buff_head *rq;
	unsigned long flags;

	if (!vcc->push)
		return -EBADFD;
	clip_vcc = kmalloc(sizeof(struct clip_vcc), GFP_KERNEL);
	if (!clip_vcc)
		return -ENOMEM;
	pr_debug("mkip clip_vcc %p vcc %p\n", clip_vcc, vcc);
	clip_vcc->vcc = vcc;
	vcc->user_back = clip_vcc;
	set_bit(ATM_VF_IS_CLIP, &vcc->flags);
	clip_vcc->entry = NULL;
	clip_vcc->xoff = 0;
	clip_vcc->encap = 1;
	clip_vcc->last_use = jiffies;
	clip_vcc->idle_timeout = timeout * HZ;
	clip_vcc->old_push = vcc->push;
	clip_vcc->old_pop = vcc->pop;
	vcc->push = clip_push;
	vcc->pop = clip_pop;

	rq = &sk_atm(vcc)->sk_receive_queue;

	spin_lock_irqsave(&rq->lock, flags);
	if (skb_queue_empty(rq)) {
		skb = NULL;
	} else {
		/* NULL terminate the list.  */
		rq->prev->next = NULL;
		skb = rq->next;
	}
	rq->prev = rq->next = (struct sk_buff *)rq;
	rq->qlen = 0;
	spin_unlock_irqrestore(&rq->lock, flags);

	/* re-process everything received between connection setup and MKIP */
	while (skb) {
		struct sk_buff *next = skb->next;

		skb->next = skb->prev = NULL;
		if (!clip_devs) {
			atm_return(vcc, skb->truesize);
			kfree_skb(skb);
		} else {
			unsigned int len = skb->len;

			skb_get(skb);
			clip_push(vcc, skb);
			PRIV(skb->dev)->stats.rx_packets--;
			PRIV(skb->dev)->stats.rx_bytes -= len;
			kfree_skb(skb);
		}

		skb = next;
	}
	return 0;
}

static int clip_setentry(struct atm_vcc *vcc, __be32 ip)
{
	struct neighbour *neigh;
	struct atmarp_entry *entry;