aarp.c

   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 *	AARP:		An implementation of the AppleTalk AARP protocol for
   4 *			Ethernet 'ELAP'.
   5 *
   6 *		Alan Cox  <Alan.Cox@linux.org>
   7 *
   8 *	This doesn't fit cleanly with the IP arp. Potentially we can use
   9 *	the generic neighbour discovery code to clean this up.
  10 *
  11 *	FIXME:
  12 *		We ought to handle the retransmits with a single list and a
  13 *	separate fast timer for when it is needed.
  14 *		Use neighbour discovery code.
  15 *		Token Ring Support.
  16 *
  17 *	References:
  18 *		Inside AppleTalk (2nd Ed).
  19 *	Fixes:
  20 *		Jaume Grau	-	flush caches on AARP_PROBE
  21 *		Rob Newberry	-	Added proxy AARP and AARP proc fs,
  22 *					moved probing from DDP module.
  23 *		Arnaldo C. Melo -	don't mangle rx packets
  24 */
  25
  26#include <linux/if_arp.h>
  27#include <linux/slab.h>
  28#include <net/sock.h>
  29#include <net/datalink.h>
  30#include <net/psnap.h>
  31#include <linux/atalk.h>
  32#include <linux/delay.h>
  33#include <linux/init.h>
  34#include <linux/proc_fs.h>
  35#include <linux/seq_file.h>
  36#include <linux/export.h>
  37#include <linux/etherdevice.h>
  38#include <linux/refcount.h>
  39
  40int sysctl_aarp_expiry_time = AARP_EXPIRY_TIME;
  41int sysctl_aarp_tick_time = AARP_TICK_TIME;
  42int sysctl_aarp_retransmit_limit = AARP_RETRANSMIT_LIMIT;
  43int sysctl_aarp_resolve_time = AARP_RESOLVE_TIME;
  44
  45/* Lists of aarp entries */
  46/**
  47 *	struct aarp_entry - AARP entry
  48 *	@refcnt: Reference count
  49 *	@last_sent: Last time we xmitted the aarp request
  50 *	@packet_queue: Queue of frames wait for resolution
  51 *	@status: Used for proxy AARP
  52 *	@expires_at: Entry expiry time
  53 *	@target_addr: DDP Address
  54 *	@dev:  Device to use
  55 *	@hwaddr:  Physical i/f address of target/router
  56 *	@xmit_count:  When this hits 10 we give up
  57 *	@next: Next entry in chain
  58 */
  59struct aarp_entry {
  60	refcount_t			refcnt;
  61	/* These first two are only used for unresolved entries */
  62	unsigned long		last_sent;
  63	struct sk_buff_head	packet_queue;
  64	int			status;
  65	unsigned long		expires_at;
  66	struct atalk_addr	target_addr;
  67	struct net_device	*dev;
  68	char			hwaddr[ETH_ALEN];
  69	unsigned short		xmit_count;
  70	struct aarp_entry	*next;
  71};
  72
  73/* Hashed list of resolved, unresolved and proxy entries */
  74static struct aarp_entry *resolved[AARP_HASH_SIZE];
  75static struct aarp_entry *unresolved[AARP_HASH_SIZE];
  76static struct aarp_entry *proxies[AARP_HASH_SIZE];
  77static int unresolved_count;
  78
  79/* One lock protects it all. */
  80static DEFINE_RWLOCK(aarp_lock);
  81
  82/* Used to walk the list and purge/kick entries.  */
  83static struct timer_list aarp_timer;
  84
  85static inline void aarp_entry_get(struct aarp_entry *a)
  86{
  87	refcount_inc(&a->refcnt);
  88}
  89
  90static inline void aarp_entry_put(struct aarp_entry *a)
  91{
  92	if (refcount_dec_and_test(&a->refcnt))
  93		kfree(a);
  94}
  95
  96/*
  97 *	Delete an aarp queue
  98 *
  99 *	Must run under aarp_lock.
 100 */
 101static void __aarp_expire(struct aarp_entry *a)
 102{
 103	skb_queue_purge(&a->packet_queue);
 104	aarp_entry_put(a);
 105}
 106
 107/*
 108 *	Send an aarp queue entry request
 109 *
 110 *	Must run under aarp_lock.
 111 */
 112static void __aarp_send_query(struct aarp_entry *a)
 113{
 114	static unsigned char aarp_eth_multicast[ETH_ALEN] =
 115					{ 0x09, 0x00, 0x07, 0xFF, 0xFF, 0xFF };
 116	struct net_device *dev = a->dev;
 117	struct elapaarp *eah;
 118	int len = dev->hard_header_len + sizeof(*eah) + aarp_dl->header_length;
 119	struct sk_buff *skb = alloc_skb(len, GFP_ATOMIC);
 120	struct atalk_addr *sat = atalk_find_dev_addr(dev);
 121
 122	if (!skb)
 123		return;
 124
 125	if (!sat) {
 126		kfree_skb(skb);
 127		return;
 128	}
 129
 130	/* Set up the buffer */
 131	skb_reserve(skb, dev->hard_header_len + aarp_dl->header_length);
 132	skb_reset_network_header(skb);
 133	skb_reset_transport_header(skb);
 134	skb_put(skb, sizeof(*eah));
 135	skb->protocol    = htons(ETH_P_ATALK);
 136	skb->dev	 = dev;
 137	eah		 = aarp_hdr(skb);
 138
 139	/* Set up the ARP */
 140	eah->hw_type	 = htons(AARP_HW_TYPE_ETHERNET);
 141	eah->pa_type	 = htons(ETH_P_ATALK);
 142	eah->hw_len	 = ETH_ALEN;
 143	eah->pa_len	 = AARP_PA_ALEN;
 144	eah->function	 = htons(AARP_REQUEST);
 145
 146	ether_addr_copy(eah->hw_src, dev->dev_addr);
 147
 148	eah->pa_src_zero = 0;
 149	eah->pa_src_net	 = sat->s_net;
 150	eah->pa_src_node = sat->s_node;
 151
 152	eth_zero_addr(eah->hw_dst);
 153
 154	eah->pa_dst_zero = 0;
 155	eah->pa_dst_net	 = a->target_addr.s_net;
 156	eah->pa_dst_node = a->target_addr.s_node;
 157
 158	/* Send it */
 159	aarp_dl->request(aarp_dl, skb, aarp_eth_multicast);
 160	/* Update the sending count */
 161	a->xmit_count++;
 162	a->last_sent = jiffies;
 163}
 164
 165/* This runs under aarp_lock and in softint context, so only atomic memory
 166 * allocations can be used. */
 167static void aarp_send_reply(struct net_device *dev, struct atalk_addr *us,
 168			    struct atalk_addr *them, unsigned char *sha)
 169{
 170	struct elapaarp *eah;
 171	int len = dev->hard_header_len + sizeof(*eah) + aarp_dl->header_length;
 172	struct sk_buff *skb = alloc_skb(len, GFP_ATOMIC);
 173
 174	if (!skb)
 175		return;
 176
 177	/* Set up the buffer */
 178	skb_reserve(skb, dev->hard_header_len + aarp_dl->header_length);
 179	skb_reset_network_header(skb);
 180	skb_reset_transport_header(skb);
 181	skb_put(skb, sizeof(*eah));
 182	skb->protocol    = htons(ETH_P_ATALK);
 183	skb->dev	 = dev;
 184	eah		 = aarp_hdr(skb);
 185
 186	/* Set up the ARP */
 187	eah->hw_type	 = htons(AARP_HW_TYPE_ETHERNET);
 188	eah->pa_type	 = htons(ETH_P_ATALK);
 189	eah->hw_len	 = ETH_ALEN;
 190	eah->pa_len	 = AARP_PA_ALEN;
 191	eah->function	 = htons(AARP_REPLY);
 192
 193	ether_addr_copy(eah->hw_src, dev->dev_addr);
 194
 195	eah->pa_src_zero = 0;
 196	eah->pa_src_net	 = us->s_net;
 197	eah->pa_src_node = us->s_node;
 198
 199	if (!sha)
 200		eth_zero_addr(eah->hw_dst);
 201	else
 202		ether_addr_copy(eah->hw_dst, sha);
 203
 204	eah->pa_dst_zero = 0;
 205	eah->pa_dst_net	 = them->s_net;
 206	eah->pa_dst_node = them->s_node;
 207
 208	/* Send it */
 209	aarp_dl->request(aarp_dl, skb, sha);
 210}
 211
 212/*
 213 *	Send probe frames. Called from aarp_probe_network and
 214 *	aarp_proxy_probe_network.
 215 */
 216
 217static void aarp_send_probe(struct net_device *dev, struct atalk_addr *us)
 218{
 219	struct elapaarp *eah;
 220	int len = dev->hard_header_len + sizeof(*eah) + aarp_dl->header_length;
 221	struct sk_buff *skb = alloc_skb(len, GFP_ATOMIC);
 222	static unsigned char aarp_eth_multicast[ETH_ALEN] =
 223					{ 0x09, 0x00, 0x07, 0xFF, 0xFF, 0xFF };
 224
 225	if (!skb)
 226		return;
 227
 228	/* Set up the buffer */
 229	skb_reserve(skb, dev->hard_header_len + aarp_dl->header_length);
 230	skb_reset_network_header(skb);
 231	skb_reset_transport_header(skb);
 232	skb_put(skb, sizeof(*eah));
 233	skb->protocol    = htons(ETH_P_ATALK);
 234	skb->dev	 = dev;
 235	eah		 = aarp_hdr(skb);
 236
 237	/* Set up the ARP */
 238	eah->hw_type	 = htons(AARP_HW_TYPE_ETHERNET);
 239	eah->pa_type	 = htons(ETH_P_ATALK);
 240	eah->hw_len	 = ETH_ALEN;
 241	eah->pa_len	 = AARP_PA_ALEN;
 242	eah->function	 = htons(AARP_PROBE);
 243
 244	ether_addr_copy(eah->hw_src, dev->dev_addr);
 245
 246	eah->pa_src_zero = 0;
 247	eah->pa_src_net	 = us->s_net;
 248	eah->pa_src_node = us->s_node;
 249
 250	eth_zero_addr(eah->hw_dst);
 251
 252	eah->pa_dst_zero = 0;
 253	eah->pa_dst_net	 = us->s_net;
 254	eah->pa_dst_node = us->s_node;
 255
 256	/* Send it */
 257	aarp_dl->request(aarp_dl, skb, aarp_eth_multicast);
 258}
 259
 260/*
 261 *	Handle an aarp timer expire
 262 *
 263 *	Must run under the aarp_lock.
 264 */
 265
 266static void __aarp_expire_timer(struct aarp_entry **n)
 267{
 268	struct aarp_entry *t;
 269
 270	while (*n)
 271		/* Expired ? */
 272		if (time_after(jiffies, (*n)->expires_at)) {
 273			t = *n;
 274			*n = (*n)->next;
 275			__aarp_expire(t);
 276		} else
 277			n = &((*n)->next);
 278}
 279
 280/*
 281 *	Kick all pending requests 5 times a second.
 282 *
 283 *	Must run under the aarp_lock.
 284 */
 285static void __aarp_kick(struct aarp_entry **n)
 286{
 287	struct aarp_entry *t;
 288
 289	while (*n)
 290		/* Expired: if this will be the 11th tx, we delete instead. */
 291		if ((*n)->xmit_count >= sysctl_aarp_retransmit_limit) {
 292			t = *n;
 293			*n = (*n)->next;
 294			__aarp_expire(t);
 295		} else {
 296			__aarp_send_query(*n);
 297			n = &((*n)->next);
 298		}
 299}
 300
 301/*
 302 *	A device has gone down. Take all entries referring to the device
 303 *	and remove them.
 304 *
 305 *	Must run under the aarp_lock.
 306 */
 307static void __aarp_expire_device(struct aarp_entry **n, struct net_device *dev)
 308{
 309	struct aarp_entry *t;
 310
 311	while (*n)
 312		if ((*n)->dev == dev) {
 313			t = *n;
 314			*n = (*n)->next;
 315			__aarp_expire(t);
 316		} else
 317			n = &((*n)->next);
 318}
 319
 320/* Handle the timer event */
 321static void aarp_expire_timeout(struct timer_list *unused)
 322{
 323	int ct;
 324
 325	write_lock_bh(&aarp_lock);
 326
 327	for (ct = 0; ct < AARP_HASH_SIZE; ct++) {
 328		__aarp_expire_timer(&resolved[ct]);
 329		__aarp_kick(&unresolved[ct]);
 330		__aarp_expire_timer(&unresolved[ct]);
 331		__aarp_expire_timer(&proxies[ct]);
 332	}
 333
 334	write_unlock_bh(&aarp_lock);
 335	mod_timer(&aarp_timer, jiffies +
 336			       (unresolved_count ? sysctl_aarp_tick_time :
 337				sysctl_aarp_expiry_time));
 338}
 339
 340/* Network device notifier chain handler. */
 341static int aarp_device_event(struct notifier_block *this, unsigned long event,
 342			     void *ptr)
 343{
 344	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 345	int ct;
 346
 347	if (!net_eq(dev_net(dev), &init_net))
 348		return NOTIFY_DONE;
 349
 350	if (event == NETDEV_DOWN) {
 351		write_lock_bh(&aarp_lock);
 352
 353		for (ct = 0; ct < AARP_HASH_SIZE; ct++) {
 354			__aarp_expire_device(&resolved[ct], dev);
 355			__aarp_expire_device(&unresolved[ct], dev);
 356			__aarp_expire_device(&proxies[ct], dev);
 357		}
 358
 359		write_unlock_bh(&aarp_lock);
 360	}
 361	return NOTIFY_DONE;
 362}
 363
 364/* Expire all entries in a hash chain */
 365static void __aarp_expire_all(struct aarp_entry **n)
 366{
 367	struct aarp_entry *t;
 368
 369	while (*n) {
 370		t = *n;
 371		*n = (*n)->next;
 372		__aarp_expire(t);
 373	}
 374}
 375
 376/* Cleanup all hash chains -- module unloading */
 377static void aarp_purge(void)
 378{
 379	int ct;
 380
 381	write_lock_bh(&aarp_lock);
 382	for (ct = 0; ct < AARP_HASH_SIZE; ct++) {
 383		__aarp_expire_all(&resolved[ct]);
 384		__aarp_expire_all(&unresolved[ct]);
 385		__aarp_expire_all(&proxies[ct]);
 386	}
 387	write_unlock_bh(&aarp_lock);
 388}
 389
 390/*
 391 *	Create a new aarp entry.  This must use GFP_ATOMIC because it
 392 *	runs while holding spinlocks.
 393 */
 394static struct aarp_entry *aarp_alloc(void)
 395{
 396	struct aarp_entry *a = kmalloc(sizeof(*a), GFP_ATOMIC);
 397	if (!a)
 398		return NULL;
 399
 400	refcount_set(&a->refcnt, 1);
 401	skb_queue_head_init(&a->packet_queue);
 402	return a;
 403}
 404
 405/*
 406 * Find an entry. We might return an expired but not yet purged entry. We
 407 * don't care as it will do no harm.
 408 *
 409 * This must run under the aarp_lock.
 410 */
 411static struct aarp_entry *__aarp_find_entry(struct aarp_entry *list,
 412					    struct net_device *dev,
 413					    struct atalk_addr *sat)
 414{
 415	while (list) {
 416		if (list->target_addr.s_net == sat->s_net &&
 417		    list->target_addr.s_node == sat->s_node &&
 418		    list->dev == dev)
 419			break;
 420		list = list->next;
 421	}
 422
 423	return list;
 424}
 425
 426/* Called from the DDP code, and thus must be exported. */
 427void aarp_proxy_remove(struct net_device *dev, struct atalk_addr *sa)
 428{
 429	int hash = sa->s_node % (AARP_HASH_SIZE - 1);
 430	struct aarp_entry *a;
 431
 432	write_lock_bh(&aarp_lock);
 433
 434	a = __aarp_find_entry(proxies[hash], dev, sa);
 435	if (a)
 436		a->expires_at = jiffies - 1;
 437
 438	write_unlock_bh(&aarp_lock);
 439}
 440
 441/* This must run under aarp_lock. */
 442static struct atalk_addr *__aarp_proxy_find(struct net_device *dev,
 443					    struct atalk_addr *sa)
 444{
 445	int hash = sa->s_node % (AARP_HASH_SIZE - 1);
 446	struct aarp_entry *a = __aarp_find_entry(proxies[hash], dev, sa);
 447
 448	return a ? sa : NULL;
 449}
 450
 451void aarp_probe_network(struct atalk_iface *atif)
 452{
 453	unsigned int count;
 454
 455	for (count = 0; count < AARP_RETRANSMIT_LIMIT; count++) {
 456		aarp_send_probe(atif->dev, &atif->address);
 457
 458		/* Defer 1/10th */
 459		msleep(100);
 460
 461		if (atif->status & ATIF_PROBE_FAIL)
 462			break;
 463	}
 464}
 465
 466int aarp_proxy_probe_network(struct atalk_iface *atif, struct atalk_addr *sa)
 467{
 468	int hash, retval = -EPROTONOSUPPORT;
 469	struct aarp_entry *entry;
 470	unsigned int count;
 471
 472	/*
 473	 * we don't currently support LocalTalk or PPP for proxy AARP;
 474	 * if someone wants to try and add it, have fun
 475	 */
 476	if (atif->dev->type == ARPHRD_LOCALTLK ||
 477	    atif->dev->type == ARPHRD_PPP)
 478		goto out;
 479
 480	/*
 481	 * create a new AARP entry with the flags set to be published --
 482	 * we need this one to hang around even if it's in use
 483	 */
 484	entry = aarp_alloc();
 485	retval = -ENOMEM;
 486	if (!entry)
 487		goto out;
 488
 489	entry->expires_at = -1;
 490	entry->status = ATIF_PROBE;
 491	entry->target_addr.s_node = sa->s_node;
 492	entry->target_addr.s_net = sa->s_net;
 493	entry->dev = atif->dev;
 494
 495	write_lock_bh(&aarp_lock);
 496	aarp_entry_get(entry);
 497
 498	hash = sa->s_node % (AARP_HASH_SIZE - 1);
 499	entry->next = proxies[hash];
 500	proxies[hash] = entry;
 501
 502	for (count = 0; count < AARP_RETRANSMIT_LIMIT; count++) {
 503		aarp_send_probe(atif->dev, sa);
 504
 505		/* Defer 1/10th */
 506		write_unlock_bh(&aarp_lock);
 507		msleep(100);
 508		write_lock_bh(&aarp_lock);
 509
 510		if (entry->status & ATIF_PROBE_FAIL)
 511			break;
 512	}
 513
 514	if (entry->status & ATIF_PROBE_FAIL) {
 515		entry->expires_at = jiffies - 1; /* free the entry */
 516		retval = -EADDRINUSE; /* return network full */
 517	} else { /* clear the probing flag */
 518		entry->status &= ~ATIF_PROBE;
 519		retval = 1;
 520	}
 521
 522	aarp_entry_put(entry);
 523	write_unlock_bh(&aarp_lock);
 524out:
 525	return retval;
 526}
 527
 528/* Send a DDP frame */
 529int aarp_send_ddp(struct net_device *dev, struct sk_buff *skb,
 530		  struct atalk_addr *sa, void *hwaddr)
 531{
 532	static char ddp_eth_multicast[ETH_ALEN] =
 533		{ 0x09, 0x00, 0x07, 0xFF, 0xFF, 0xFF };
 534	int hash;
 535	struct aarp_entry *a;
 536
 537	skb_reset_network_header(skb);
 538
 539	/* Check for LocalTalk first */
 540	if (dev->type == ARPHRD_LOCALTLK) {
 541		struct atalk_addr *at = atalk_find_dev_addr(dev);
 542		struct ddpehdr *ddp = (struct ddpehdr *)skb->data;
 543		int ft = 2;
 544
 545		/*
 546		 * Compressible ?
 547		 *
 548		 * IFF: src_net == dest_net == device_net
 549		 * (zero matches anything)
 550		 */
 551
 552		if ((!ddp->deh_snet || at->s_net == ddp->deh_snet) &&
 553		    (!ddp->deh_dnet || at->s_net == ddp->deh_dnet)) {
 554			skb_pull(skb, sizeof(*ddp) - 4);
 555
 556			/*
 557			 *	The upper two remaining bytes are the port
 558			 *	numbers	we just happen to need. Now put the
 559			 *	length in the lower two.
 560			 */
 561			*((__be16 *)skb->data) = htons(skb->len);
 562			ft = 1;
 563		}
 564		/*
 565		 * Nice and easy. No AARP type protocols occur here so we can
 566		 * just shovel it out with a 3 byte LLAP header
 567		 */
 568
 569		skb_push(skb, 3);
 570		skb->data[0] = sa->s_node;
 571		skb->data[1] = at->s_node;
 572		skb->data[2] = ft;
 573		skb->dev     = dev;
 574		goto sendit;
 575	}
 576
 577	/* On a PPP link we neither compress nor aarp.  */
 578	if (dev->type == ARPHRD_PPP) {
 579		skb->protocol = htons(ETH_P_PPPTALK);
 580		skb->dev = dev;
 581		goto sendit;
 582	}
 583
 584	/* Non ELAP we cannot do. */
 585	if (dev->type != ARPHRD_ETHER)
 586		goto free_it;
 587
 588	skb->dev = dev;
 589	skb->protocol = htons(ETH_P_ATALK);
 590	hash = sa->s_node % (AARP_HASH_SIZE - 1);
 591
 592	/* Do we have a resolved entry? */
 593	if (sa->s_node == ATADDR_BCAST) {
 594		/* Send it */
 595		ddp_dl->request(ddp_dl, skb, ddp_eth_multicast);
 596		goto sent;
 597	}
 598
 599	write_lock_bh(&aarp_lock);
 600	a = __aarp_find_entry(resolved[hash], dev, sa);
 601
 602	if (a) { /* Return 1 and fill in the address */
 603		a->expires_at = jiffies + (sysctl_aarp_expiry_time * 10);
 604		ddp_dl->request(ddp_dl, skb, a->hwaddr);
 605		write_unlock_bh(&aarp_lock);
 606		goto sent;
 607	}
 608
 609	/* Do we have an unresolved entry: This is the less common path */
 610	a = __aarp_find_entry(unresolved[hash], dev, sa);
 611	if (a) { /* Queue onto the unresolved queue */
 612		skb_queue_tail(&a->packet_queue, skb);
 613		goto out_unlock;
 614	}
 615
 616	/* Allocate a new entry */
 617	a = aarp_alloc();
 618	if (!a) {
 619		/* Whoops slipped... good job it's an unreliable protocol 8) */
 620		write_unlock_bh(&aarp_lock);
 621		goto free_it;
 622	}
 623
 624	/* Set up the queue */
 625	skb_queue_tail(&a->packet_queue, skb);
 626	a->expires_at	 = jiffies + sysctl_aarp_resolve_time;
 627	a->dev		 = dev;
 628	a->next		 = unresolved[hash];
 629	a->target_addr	 = *sa;
 630	a->xmit_count	 = 0;
 631	unresolved[hash] = a;
 632	unresolved_count++;
 633
 634	/* Send an initial request for the address */
 635	__aarp_send_query(a);
 636
 637	/*
 638	 * Switch to fast timer if needed (That is if this is the first
 639	 * unresolved entry to get added)
 640	 */
 641
 642	if (unresolved_count == 1)
 643		mod_timer(&aarp_timer, jiffies + sysctl_aarp_tick_time);
 644
 645	/* Now finally, it is safe to drop the lock. */
 646out_unlock:
 647	write_unlock_bh(&aarp_lock);
 648
 649	/* Tell the ddp layer we have taken over for this frame. */
 650	goto sent;
 651
 652sendit:
 653	if (skb->sk)
 654		skb->priority = READ_ONCE(skb->sk->sk_priority);
 655	if (dev_queue_xmit(skb))
 656		goto drop;
 657sent:
 658	return NET_XMIT_SUCCESS;
 659free_it:
 660	kfree_skb(skb);
 661drop:
 662	return NET_XMIT_DROP;
 663}
 664EXPORT_SYMBOL(aarp_send_ddp);
 665
 666/*
 667 *	An entry in the aarp unresolved queue has become resolved. Send
 668 *	all the frames queued under it.
 669 *
 670 *	Must run under aarp_lock.
 671 */
 672static void __aarp_resolved(struct aarp_entry **list, struct aarp_entry *a,
 673			    int hash)
 674{
 675	struct sk_buff *skb;
 676
 677	while (*list)
 678		if (*list == a) {
 679			unresolved_count--;
 680			*list = a->next;
 681
 682			/* Move into the resolved list */
 683			a->next = resolved[hash];
 684			resolved[hash] = a;
 685
 686			/* Kick frames off */
 687			while ((skb = skb_dequeue(&a->packet_queue)) != NULL) {
 688				a->expires_at = jiffies +
 689						sysctl_aarp_expiry_time * 10;
 690				ddp_dl->request(ddp_dl, skb, a->hwaddr);
 691			}
 692		} else
 693			list = &((*list)->next);
 694}
 695
 696/*
 697 *	This is called by the SNAP driver whenever we see an AARP SNAP
 698 *	frame. We currently only support Ethernet.
 699 */
 700static int aarp_rcv(struct sk_buff *skb, struct net_device *dev,
 701		    struct packet_type *pt, struct net_device *orig_dev)
 702{
 703	struct elapaarp *ea = aarp_hdr(skb);
 704	int hash, ret = 0;
 705	__u16 function;
 706	struct aarp_entry *a;
 707	struct atalk_addr sa, *ma, da;
 708	struct atalk_iface *ifa;
 709
 710	if (!net_eq(dev_net(dev), &init_net))
 711		goto out0;
 712
 713	/* We only do Ethernet SNAP AARP. */
 714	if (dev->type != ARPHRD_ETHER)
 715		goto out0;
 716
 717	/* Frame size ok? */
 718	if (!skb_pull(skb, sizeof(*ea)))
 719		goto out0;
 720
 721	function = ntohs(ea->function);
 722
 723	/* Sanity check fields. */
 724	if (function < AARP_REQUEST || function > AARP_PROBE ||
 725	    ea->hw_len != ETH_ALEN || ea->pa_len != AARP_PA_ALEN ||
 726	    ea->pa_src_zero || ea->pa_dst_zero)
 727		goto out0;
 728
 729	/* Looks good. */
 730	hash = ea->pa_src_node % (AARP_HASH_SIZE - 1);
 731
 732	/* Build an address. */
 733	sa.s_node = ea->pa_src_node;
 734	sa.s_net = ea->pa_src_net;
 735
 736	/* Process the packet. Check for replies of me. */
 737	ifa = atalk_find_dev(dev);
 738	if (!ifa)
 739		goto out1;
 740
 741	if (ifa->status & ATIF_PROBE &&
 742	    ifa->address.s_node == ea->pa_dst_node &&
 743	    ifa->address.s_net == ea->pa_dst_net) {
 744		ifa->status |= ATIF_PROBE_FAIL; /* Fail the probe (in use) */
 745		goto out1;
 746	}
 747
 748	/* Check for replies of proxy AARP entries */
 749	da.s_node = ea->pa_dst_node;
 750	da.s_net  = ea->pa_dst_net;
 751
 752	write_lock_bh(&aarp_lock);
 753	a = __aarp_find_entry(proxies[hash], dev, &da);
 754
 755	if (a && a->status & ATIF_PROBE) {
 756		a->status |= ATIF_PROBE_FAIL;
 757		/*
 758		 * we do not respond to probe or request packets of
 759		 * this address while we are probing this address
 760		 */
 761		goto unlock;
 762	}
 763
 764	switch (function) {
 765	case AARP_REPLY:
 766		if (!unresolved_count)	/* Speed up */
 767			break;
 768
 769		/* Find the entry.  */
 770		a = __aarp_find_entry(unresolved[hash], dev, &sa);
 771		if (!a || dev != a->dev)
 772			break;
 773
 774		/* We can fill one in - this is good. */
 775		ether_addr_copy(a->hwaddr, ea->hw_src);
 776		__aarp_resolved(&unresolved[hash], a, hash);
 777		if (!unresolved_count)
 778			mod_timer(&aarp_timer,
 779				  jiffies + sysctl_aarp_expiry_time);
 780		break;
 781
 782	case AARP_REQUEST:
 783	case AARP_PROBE:
 784
 785		/*
 786		 * If it is my address set ma to my address and reply.
 787		 * We can treat probe and request the same.  Probe
 788		 * simply means we shouldn't cache the querying host,
 789		 * as in a probe they are proposing an address not
 790		 * using one.
 791		 *
 792		 * Support for proxy-AARP added. We check if the
 793		 * address is one of our proxies before we toss the
 794		 * packet out.
 795		 */
 796
 797		sa.s_node = ea->pa_dst_node;
 798		sa.s_net  = ea->pa_dst_net;
 799
 800		/* See if we have a matching proxy. */
 801		ma = __aarp_proxy_find(dev, &sa);
 802		if (!ma)
 803			ma = &ifa->address;
 804		else { /* We need to make a copy of the entry. */
 805			da.s_node = sa.s_node;
 806			da.s_net = sa.s_net;
 807			ma = &da;
 808		}
 809
 810		if (function == AARP_PROBE) {
 811			/*
 812			 * A probe implies someone trying to get an
 813			 * address. So as a precaution flush any
 814			 * entries we have for this address.
 815			 */
 816			a = __aarp_find_entry(resolved[sa.s_node %
 817						       (AARP_HASH_SIZE - 1)],
 818					      skb->dev, &sa);
 819
 820			/*
 821			 * Make it expire next tick - that avoids us
 822			 * getting into a probe/flush/learn/probe/
 823			 * flush/learn cycle during probing of a slow
 824			 * to respond host addr.
 825			 */
 826			if (a) {
 827				a->expires_at = jiffies - 1;
 828				mod_timer(&aarp_timer, jiffies +
 829					  sysctl_aarp_tick_time);
 830			}
 831		}
 832
 833		if (sa.s_node != ma->s_node)
 834			break;
 835
 836		if (sa.s_net && ma->s_net && sa.s_net != ma->s_net)
 837			break;
 838
 839		sa.s_node = ea->pa_src_node;
 840		sa.s_net = ea->pa_src_net;
 841
 842		/* aarp_my_address has found the address to use for us.
 843		 */
 844		aarp_send_reply(dev, ma, &sa, ea->hw_src);
 845		break;
 846	}
 847
 848unlock:
 849	write_unlock_bh(&aarp_lock);
 850out1:
 851	ret = 1;
 852out0:
 853	kfree_skb(skb);
 854	return ret;
 855}
 856
 857static struct notifier_block aarp_notifier = {
 858	.notifier_call = aarp_device_event,
 859};
 860
 861static unsigned char aarp_snap_id[] = { 0x00, 0x00, 0x00, 0x80, 0xF3 };
 862
 863int __init aarp_proto_init(void)
 864{
 865	int rc;
 866
 867	aarp_dl = register_snap_client(aarp_snap_id, aarp_rcv);
 868	if (!aarp_dl) {
 869		printk(KERN_CRIT "Unable to register AARP with SNAP.\n");
 870		return -ENOMEM;
 871	}
 872	timer_setup(&aarp_timer, aarp_expire_timeout, 0);
 873	aarp_timer.expires  = jiffies + sysctl_aarp_expiry_time;
 874	add_timer(&aarp_timer);
 875	rc = register_netdevice_notifier(&aarp_notifier);
 876	if (rc) {
 877		timer_delete_sync(&aarp_timer);
 878		unregister_snap_client(aarp_dl);
 879	}
 880	return rc;
 881}
 882
 883/* Remove the AARP entries associated with a device. */
 884void aarp_device_down(struct net_device *dev)
 885{
 886	int ct;
 887
 888	write_lock_bh(&aarp_lock);
 889
 890	for (ct = 0; ct < AARP_HASH_SIZE; ct++) {
 891		__aarp_expire_device(&resolved[ct], dev);
 892		__aarp_expire_device(&unresolved[ct], dev);
 893		__aarp_expire_device(&proxies[ct], dev);
 894	}
 895
 896	write_unlock_bh(&aarp_lock);
 897}
 898
 899#ifdef CONFIG_PROC_FS
 900/*
 901 * Get the aarp entry that is in the chain described
 902 * by the iterator.
 903 * If pos is set then skip till that index.
 904 * pos = 1 is the first entry
 905 */
 906static struct aarp_entry *iter_next(struct aarp_iter_state *iter, loff_t *pos)
 907{
 908	int ct = iter->bucket;
 909	struct aarp_entry **table = iter->table;
 910	loff_t off = 0;
 911	struct aarp_entry *entry;
 912
 913 rescan:
 914	while (ct < AARP_HASH_SIZE) {
 915		for (entry = table[ct]; entry; entry = entry->next) {
 916			if (!pos || ++off == *pos) {
 917				iter->table = table;
 918				iter->bucket = ct;
 919				return entry;
 920			}
 921		}
 922		++ct;
 923	}
 924
 925	if (table == resolved) {
 926		ct = 0;
 927		table = unresolved;
 928		goto rescan;
 929	}
 930	if (table == unresolved) {
 931		ct = 0;
 932		table = proxies;
 933		goto rescan;
 934	}
 935	return NULL;
 936}
 937
 938static void *aarp_seq_start(struct seq_file *seq, loff_t *pos)
 939	__acquires(aarp_lock)
 940{
 941	struct aarp_iter_state *iter = seq->private;
 942
 943	read_lock_bh(&aarp_lock);
 944	iter->table     = resolved;
 945	iter->bucket    = 0;
 946
 947	return *pos ? iter_next(iter, pos) : SEQ_START_TOKEN;
 948}
 949
 950static void *aarp_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 951{
 952	struct aarp_entry *entry = v;
 953	struct aarp_iter_state *iter = seq->private;
 954
 955	++*pos;
 956
 957	/* first line after header */
 958	if (v == SEQ_START_TOKEN)
 959		entry = iter_next(iter, NULL);
 960
 961	/* next entry in current bucket */
 962	else if (entry->next)
 963		entry = entry->next;
 964
 965	/* next bucket or table */
 966	else {
 967		++iter->bucket;
 968		entry = iter_next(iter, NULL);
 969	}
 970	return entry;
 971}
 972
 973static void aarp_seq_stop(struct seq_file *seq, void *v)
 974	__releases(aarp_lock)
 975{
 976	read_unlock_bh(&aarp_lock);
 977}
 978
 979static const char *dt2str(unsigned long ticks)
 980{
 981	static char buf[32];
 982
 983	sprintf(buf, "%ld.%02ld", ticks / HZ, ((ticks % HZ) * 100) / HZ);
 984
 985	return buf;
 986}
 987
 988static int aarp_seq_show(struct seq_file *seq, void *v)
 989{
 990	struct aarp_iter_state *iter = seq->private;
 991	struct aarp_entry *entry = v;
 992	unsigned long now = jiffies;
 993
 994	if (v == SEQ_START_TOKEN)
 995		seq_puts(seq,
 996			 "Address  Interface   Hardware Address"
 997			 "   Expires LastSend  Retry Status\n");
 998	else {
 999		seq_printf(seq, "%04X:%02X  %-12s",
1000			   ntohs(entry->target_addr.s_net),
1001			   (unsigned int) entry->target_addr.s_node,
1002			   entry->dev ? entry->dev->name : "????");
1003		seq_printf(seq, "%pM", entry->hwaddr);
1004		seq_printf(seq, " %8s",
1005			   dt2str((long)entry->expires_at - (long)now));
1006		if (iter->table == unresolved)
1007			seq_printf(seq, " %8s %6hu",
1008				   dt2str(now - entry->last_sent),
1009				   entry->xmit_count);
1010		else
1011			seq_puts(seq, "                ");
1012		seq_printf(seq, " %s\n",
1013			   (iter->table == resolved) ? "resolved"
1014			   : (iter->table == unresolved) ? "unresolved"
1015			   : (iter->table == proxies) ? "proxies"
1016			   : "unknown");
1017	}
1018	return 0;
1019}
1020
1021const struct seq_operations aarp_seq_ops = {
1022	.start  = aarp_seq_start,
1023	.next   = aarp_seq_next,
1024	.stop   = aarp_seq_stop,
1025	.show   = aarp_seq_show,
1026};
1027#endif
1028
1029/* General module cleanup. Called from cleanup_module() in ddp.c. */
1030void aarp_cleanup_module(void)
1031{
1032	timer_delete_sync(&aarp_timer);
1033	unregister_netdevice_notifier(&aarp_notifier);
1034	unregister_snap_client(aarp_dl);
1035	aarp_purge();
1036}