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Linux/net/appletalk/aarp.c

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  1 /*
  2  *      AARP:           An implementation of the AppleTalk AARP protocol for
  3  *                      Ethernet 'ELAP'.
  4  *
  5  *              Alan Cox  <Alan.Cox@linux.org>
  6  *
  7  *      This doesn't fit cleanly with the IP arp. Potentially we can use
  8  *      the generic neighbour discovery code to clean this up.
  9  *
 10  *      FIXME:
 11  *              We ought to handle the retransmits with a single list and a
 12  *      separate fast timer for when it is needed.
 13  *              Use neighbour discovery code.
 14  *              Token Ring Support.
 15  *
 16  *              This program is free software; you can redistribute it and/or
 17  *              modify it under the terms of the GNU General Public License
 18  *              as published by the Free Software Foundation; either version
 19  *              2 of the License, or (at your option) any later version.
 20  *
 21  *
 22  *      References:
 23  *              Inside AppleTalk (2nd Ed).
 24  *      Fixes:
 25  *              Jaume Grau      -       flush caches on AARP_PROBE
 26  *              Rob Newberry    -       Added proxy AARP and AARP proc fs,
 27  *                                      moved probing from DDP module.
 28  *              Arnaldo C. Melo -       don't mangle rx packets
 29  *
 30  */
 31 
 32 #include <linux/if_arp.h>
 33 #include <linux/slab.h>
 34 #include <net/sock.h>
 35 #include <net/datalink.h>
 36 #include <net/psnap.h>
 37 #include <linux/atalk.h>
 38 #include <linux/delay.h>
 39 #include <linux/init.h>
 40 #include <linux/proc_fs.h>
 41 #include <linux/seq_file.h>
 42 #include <linux/export.h>
 43 #include <linux/etherdevice.h>
 44 
 45 int sysctl_aarp_expiry_time = AARP_EXPIRY_TIME;
 46 int sysctl_aarp_tick_time = AARP_TICK_TIME;
 47 int sysctl_aarp_retransmit_limit = AARP_RETRANSMIT_LIMIT;
 48 int sysctl_aarp_resolve_time = AARP_RESOLVE_TIME;
 49 
 50 /* Lists of aarp entries */
 51 /**
 52  *      struct aarp_entry - AARP entry
 53  *      @last_sent - Last time we xmitted the aarp request
 54  *      @packet_queue - Queue of frames wait for resolution
 55  *      @status - Used for proxy AARP
 56  *      expires_at - Entry expiry time
 57  *      target_addr - DDP Address
 58  *      dev - Device to use
 59  *      hwaddr - Physical i/f address of target/router
 60  *      xmit_count - When this hits 10 we give up
 61  *      next - Next entry in chain
 62  */
 63 struct aarp_entry {
 64         /* These first two are only used for unresolved entries */
 65         unsigned long           last_sent;
 66         struct sk_buff_head     packet_queue;
 67         int                     status;
 68         unsigned long           expires_at;
 69         struct atalk_addr       target_addr;
 70         struct net_device       *dev;
 71         char                    hwaddr[ETH_ALEN];
 72         unsigned short          xmit_count;
 73         struct aarp_entry       *next;
 74 };
 75 
 76 /* Hashed list of resolved, unresolved and proxy entries */
 77 static struct aarp_entry *resolved[AARP_HASH_SIZE];
 78 static struct aarp_entry *unresolved[AARP_HASH_SIZE];
 79 static struct aarp_entry *proxies[AARP_HASH_SIZE];
 80 static int unresolved_count;
 81 
 82 /* One lock protects it all. */
 83 static DEFINE_RWLOCK(aarp_lock);
 84 
 85 /* Used to walk the list and purge/kick entries.  */
 86 static struct timer_list aarp_timer;
 87 
 88 /*
 89  *      Delete an aarp queue
 90  *
 91  *      Must run under aarp_lock.
 92  */
 93 static void __aarp_expire(struct aarp_entry *a)
 94 {
 95         skb_queue_purge(&a->packet_queue);
 96         kfree(a);
 97 }
 98 
 99 /*
100  *      Send an aarp queue entry request
101  *
102  *      Must run under aarp_lock.
103  */
104 static void __aarp_send_query(struct aarp_entry *a)
105 {
106         static unsigned char aarp_eth_multicast[ETH_ALEN] =
107                                         { 0x09, 0x00, 0x07, 0xFF, 0xFF, 0xFF };
108         struct net_device *dev = a->dev;
109         struct elapaarp *eah;
110         int len = dev->hard_header_len + sizeof(*eah) + aarp_dl->header_length;
111         struct sk_buff *skb = alloc_skb(len, GFP_ATOMIC);
112         struct atalk_addr *sat = atalk_find_dev_addr(dev);
113 
114         if (!skb)
115                 return;
116 
117         if (!sat) {
118                 kfree_skb(skb);
119                 return;
120         }
121 
122         /* Set up the buffer */
123         skb_reserve(skb, dev->hard_header_len + aarp_dl->header_length);
124         skb_reset_network_header(skb);
125         skb_reset_transport_header(skb);
126         skb_put(skb, sizeof(*eah));
127         skb->protocol    = htons(ETH_P_ATALK);
128         skb->dev         = dev;
129         eah              = aarp_hdr(skb);
130 
131         /* Set up the ARP */
132         eah->hw_type     = htons(AARP_HW_TYPE_ETHERNET);
133         eah->pa_type     = htons(ETH_P_ATALK);
134         eah->hw_len      = ETH_ALEN;
135         eah->pa_len      = AARP_PA_ALEN;
136         eah->function    = htons(AARP_REQUEST);
137 
138         ether_addr_copy(eah->hw_src, dev->dev_addr);
139 
140         eah->pa_src_zero = 0;
141         eah->pa_src_net  = sat->s_net;
142         eah->pa_src_node = sat->s_node;
143 
144         eth_zero_addr(eah->hw_dst);
145 
146         eah->pa_dst_zero = 0;
147         eah->pa_dst_net  = a->target_addr.s_net;
148         eah->pa_dst_node = a->target_addr.s_node;
149 
150         /* Send it */
151         aarp_dl->request(aarp_dl, skb, aarp_eth_multicast);
152         /* Update the sending count */
153         a->xmit_count++;
154         a->last_sent = jiffies;
155 }
156 
157 /* This runs under aarp_lock and in softint context, so only atomic memory
158  * allocations can be used. */
159 static void aarp_send_reply(struct net_device *dev, struct atalk_addr *us,
160                             struct atalk_addr *them, unsigned char *sha)
161 {
162         struct elapaarp *eah;
163         int len = dev->hard_header_len + sizeof(*eah) + aarp_dl->header_length;
164         struct sk_buff *skb = alloc_skb(len, GFP_ATOMIC);
165 
166         if (!skb)
167                 return;
168 
169         /* Set up the buffer */
170         skb_reserve(skb, dev->hard_header_len + aarp_dl->header_length);
171         skb_reset_network_header(skb);
172         skb_reset_transport_header(skb);
173         skb_put(skb, sizeof(*eah));
174         skb->protocol    = htons(ETH_P_ATALK);
175         skb->dev         = dev;
176         eah              = aarp_hdr(skb);
177 
178         /* Set up the ARP */
179         eah->hw_type     = htons(AARP_HW_TYPE_ETHERNET);
180         eah->pa_type     = htons(ETH_P_ATALK);
181         eah->hw_len      = ETH_ALEN;
182         eah->pa_len      = AARP_PA_ALEN;
183         eah->function    = htons(AARP_REPLY);
184 
185         ether_addr_copy(eah->hw_src, dev->dev_addr);
186 
187         eah->pa_src_zero = 0;
188         eah->pa_src_net  = us->s_net;
189         eah->pa_src_node = us->s_node;
190 
191         if (!sha)
192                 eth_zero_addr(eah->hw_dst);
193         else
194                 ether_addr_copy(eah->hw_dst, sha);
195 
196         eah->pa_dst_zero = 0;
197         eah->pa_dst_net  = them->s_net;
198         eah->pa_dst_node = them->s_node;
199 
200         /* Send it */
201         aarp_dl->request(aarp_dl, skb, sha);
202 }
203 
204 /*
205  *      Send probe frames. Called from aarp_probe_network and
206  *      aarp_proxy_probe_network.
207  */
208 
209 static void aarp_send_probe(struct net_device *dev, struct atalk_addr *us)
210 {
211         struct elapaarp *eah;
212         int len = dev->hard_header_len + sizeof(*eah) + aarp_dl->header_length;
213         struct sk_buff *skb = alloc_skb(len, GFP_ATOMIC);
214         static unsigned char aarp_eth_multicast[ETH_ALEN] =
215                                         { 0x09, 0x00, 0x07, 0xFF, 0xFF, 0xFF };
216 
217         if (!skb)
218                 return;
219 
220         /* Set up the buffer */
221         skb_reserve(skb, dev->hard_header_len + aarp_dl->header_length);
222         skb_reset_network_header(skb);
223         skb_reset_transport_header(skb);
224         skb_put(skb, sizeof(*eah));
225         skb->protocol    = htons(ETH_P_ATALK);
226         skb->dev         = dev;
227         eah              = aarp_hdr(skb);
228 
229         /* Set up the ARP */
230         eah->hw_type     = htons(AARP_HW_TYPE_ETHERNET);
231         eah->pa_type     = htons(ETH_P_ATALK);
232         eah->hw_len      = ETH_ALEN;
233         eah->pa_len      = AARP_PA_ALEN;
234         eah->function    = htons(AARP_PROBE);
235 
236         ether_addr_copy(eah->hw_src, dev->dev_addr);
237 
238         eah->pa_src_zero = 0;
239         eah->pa_src_net  = us->s_net;
240         eah->pa_src_node = us->s_node;
241 
242         eth_zero_addr(eah->hw_dst);
243 
244         eah->pa_dst_zero = 0;
245         eah->pa_dst_net  = us->s_net;
246         eah->pa_dst_node = us->s_node;
247 
248         /* Send it */
249         aarp_dl->request(aarp_dl, skb, aarp_eth_multicast);
250 }
251 
252 /*
253  *      Handle an aarp timer expire
254  *
255  *      Must run under the aarp_lock.
256  */
257 
258 static void __aarp_expire_timer(struct aarp_entry **n)
259 {
260         struct aarp_entry *t;
261 
262         while (*n)
263                 /* Expired ? */
264                 if (time_after(jiffies, (*n)->expires_at)) {
265                         t = *n;
266                         *n = (*n)->next;
267                         __aarp_expire(t);
268                 } else
269                         n = &((*n)->next);
270 }
271 
272 /*
273  *      Kick all pending requests 5 times a second.
274  *
275  *      Must run under the aarp_lock.
276  */
277 static void __aarp_kick(struct aarp_entry **n)
278 {
279         struct aarp_entry *t;
280 
281         while (*n)
282                 /* Expired: if this will be the 11th tx, we delete instead. */
283                 if ((*n)->xmit_count >= sysctl_aarp_retransmit_limit) {
284                         t = *n;
285                         *n = (*n)->next;
286                         __aarp_expire(t);
287                 } else {
288                         __aarp_send_query(*n);
289                         n = &((*n)->next);
290                 }
291 }
292 
293 /*
294  *      A device has gone down. Take all entries referring to the device
295  *      and remove them.
296  *
297  *      Must run under the aarp_lock.
298  */
299 static void __aarp_expire_device(struct aarp_entry **n, struct net_device *dev)
300 {
301         struct aarp_entry *t;
302 
303         while (*n)
304                 if ((*n)->dev == dev) {
305                         t = *n;
306                         *n = (*n)->next;
307                         __aarp_expire(t);
308                 } else
309                         n = &((*n)->next);
310 }
311 
312 /* Handle the timer event */
313 static void aarp_expire_timeout(struct timer_list *unused)
314 {
315         int ct;
316 
317         write_lock_bh(&aarp_lock);
318 
319         for (ct = 0; ct < AARP_HASH_SIZE; ct++) {
320                 __aarp_expire_timer(&resolved[ct]);
321                 __aarp_kick(&unresolved[ct]);
322                 __aarp_expire_timer(&unresolved[ct]);
323                 __aarp_expire_timer(&proxies[ct]);
324         }
325 
326         write_unlock_bh(&aarp_lock);
327         mod_timer(&aarp_timer, jiffies +
328                                (unresolved_count ? sysctl_aarp_tick_time :
329                                 sysctl_aarp_expiry_time));
330 }
331 
332 /* Network device notifier chain handler. */
333 static int aarp_device_event(struct notifier_block *this, unsigned long event,
334                              void *ptr)
335 {
336         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
337         int ct;
338 
339         if (!net_eq(dev_net(dev), &init_net))
340                 return NOTIFY_DONE;
341 
342         if (event == NETDEV_DOWN) {
343                 write_lock_bh(&aarp_lock);
344 
345                 for (ct = 0; ct < AARP_HASH_SIZE; ct++) {
346                         __aarp_expire_device(&resolved[ct], dev);
347                         __aarp_expire_device(&unresolved[ct], dev);
348                         __aarp_expire_device(&proxies[ct], dev);
349                 }
350 
351                 write_unlock_bh(&aarp_lock);
352         }
353         return NOTIFY_DONE;
354 }
355 
356 /* Expire all entries in a hash chain */
357 static void __aarp_expire_all(struct aarp_entry **n)
358 {
359         struct aarp_entry *t;
360 
361         while (*n) {
362                 t = *n;
363                 *n = (*n)->next;
364                 __aarp_expire(t);
365         }
366 }
367 
368 /* Cleanup all hash chains -- module unloading */
369 static void aarp_purge(void)
370 {
371         int ct;
372 
373         write_lock_bh(&aarp_lock);
374         for (ct = 0; ct < AARP_HASH_SIZE; ct++) {
375                 __aarp_expire_all(&resolved[ct]);
376                 __aarp_expire_all(&unresolved[ct]);
377                 __aarp_expire_all(&proxies[ct]);
378         }
379         write_unlock_bh(&aarp_lock);
380 }
381 
382 /*
383  *      Create a new aarp entry.  This must use GFP_ATOMIC because it
384  *      runs while holding spinlocks.
385  */
386 static struct aarp_entry *aarp_alloc(void)
387 {
388         struct aarp_entry *a = kmalloc(sizeof(*a), GFP_ATOMIC);
389 
390         if (a)
391                 skb_queue_head_init(&a->packet_queue);
392         return a;
393 }
394 
395 /*
396  * Find an entry. We might return an expired but not yet purged entry. We
397  * don't care as it will do no harm.
398  *
399  * This must run under the aarp_lock.
400  */
401 static struct aarp_entry *__aarp_find_entry(struct aarp_entry *list,
402                                             struct net_device *dev,
403                                             struct atalk_addr *sat)
404 {
405         while (list) {
406                 if (list->target_addr.s_net == sat->s_net &&
407                     list->target_addr.s_node == sat->s_node &&
408                     list->dev == dev)
409                         break;
410                 list = list->next;
411         }
412 
413         return list;
414 }
415 
416 /* Called from the DDP code, and thus must be exported. */
417 void aarp_proxy_remove(struct net_device *dev, struct atalk_addr *sa)
418 {
419         int hash = sa->s_node % (AARP_HASH_SIZE - 1);
420         struct aarp_entry *a;
421 
422         write_lock_bh(&aarp_lock);
423 
424         a = __aarp_find_entry(proxies[hash], dev, sa);
425         if (a)
426                 a->expires_at = jiffies - 1;
427 
428         write_unlock_bh(&aarp_lock);
429 }
430 
431 /* This must run under aarp_lock. */
432 static struct atalk_addr *__aarp_proxy_find(struct net_device *dev,
433                                             struct atalk_addr *sa)
434 {
435         int hash = sa->s_node % (AARP_HASH_SIZE - 1);
436         struct aarp_entry *a = __aarp_find_entry(proxies[hash], dev, sa);
437 
438         return a ? sa : NULL;
439 }
440 
441 /*
442  * Probe a Phase 1 device or a device that requires its Net:Node to
443  * be set via an ioctl.
444  */
445 static void aarp_send_probe_phase1(struct atalk_iface *iface)
446 {
447         struct ifreq atreq;
448         struct sockaddr_at *sa = (struct sockaddr_at *)&atreq.ifr_addr;
449         const struct net_device_ops *ops = iface->dev->netdev_ops;
450 
451         sa->sat_addr.s_node = iface->address.s_node;
452         sa->sat_addr.s_net = ntohs(iface->address.s_net);
453 
454         /* We pass the Net:Node to the drivers/cards by a Device ioctl. */
455         if (!(ops->ndo_do_ioctl(iface->dev, &atreq, SIOCSIFADDR))) {
456                 ops->ndo_do_ioctl(iface->dev, &atreq, SIOCGIFADDR);
457                 if (iface->address.s_net != htons(sa->sat_addr.s_net) ||
458                     iface->address.s_node != sa->sat_addr.s_node)
459                         iface->status |= ATIF_PROBE_FAIL;
460 
461                 iface->address.s_net  = htons(sa->sat_addr.s_net);
462                 iface->address.s_node = sa->sat_addr.s_node;
463         }
464 }
465 
466 
467 void aarp_probe_network(struct atalk_iface *atif)
468 {
469         if (atif->dev->type == ARPHRD_LOCALTLK ||
470             atif->dev->type == ARPHRD_PPP)
471                 aarp_send_probe_phase1(atif);
472         else {
473                 unsigned int count;
474 
475                 for (count = 0; count < AARP_RETRANSMIT_LIMIT; count++) {
476                         aarp_send_probe(atif->dev, &atif->address);
477 
478                         /* Defer 1/10th */
479                         msleep(100);
480 
481                         if (atif->status & ATIF_PROBE_FAIL)
482                                 break;
483                 }
484         }
485 }
486 
487 int aarp_proxy_probe_network(struct atalk_iface *atif, struct atalk_addr *sa)
488 {
489         int hash, retval = -EPROTONOSUPPORT;
490         struct aarp_entry *entry;
491         unsigned int count;
492 
493         /*
494          * we don't currently support LocalTalk or PPP for proxy AARP;
495          * if someone wants to try and add it, have fun
496          */
497         if (atif->dev->type == ARPHRD_LOCALTLK ||
498             atif->dev->type == ARPHRD_PPP)
499                 goto out;
500 
501         /*
502          * create a new AARP entry with the flags set to be published --
503          * we need this one to hang around even if it's in use
504          */
505         entry = aarp_alloc();
506         retval = -ENOMEM;
507         if (!entry)
508                 goto out;
509 
510         entry->expires_at = -1;
511         entry->status = ATIF_PROBE;
512         entry->target_addr.s_node = sa->s_node;
513         entry->target_addr.s_net = sa->s_net;
514         entry->dev = atif->dev;
515 
516         write_lock_bh(&aarp_lock);
517 
518         hash = sa->s_node % (AARP_HASH_SIZE - 1);
519         entry->next = proxies[hash];
520         proxies[hash] = entry;
521 
522         for (count = 0; count < AARP_RETRANSMIT_LIMIT; count++) {
523                 aarp_send_probe(atif->dev, sa);
524 
525                 /* Defer 1/10th */
526                 write_unlock_bh(&aarp_lock);
527                 msleep(100);
528                 write_lock_bh(&aarp_lock);
529 
530                 if (entry->status & ATIF_PROBE_FAIL)
531                         break;
532         }
533 
534         if (entry->status & ATIF_PROBE_FAIL) {
535                 entry->expires_at = jiffies - 1; /* free the entry */
536                 retval = -EADDRINUSE; /* return network full */
537         } else { /* clear the probing flag */
538                 entry->status &= ~ATIF_PROBE;
539                 retval = 1;
540         }
541 
542         write_unlock_bh(&aarp_lock);
543 out:
544         return retval;
545 }
546 
547 /* Send a DDP frame */
548 int aarp_send_ddp(struct net_device *dev, struct sk_buff *skb,
549                   struct atalk_addr *sa, void *hwaddr)
550 {
551         static char ddp_eth_multicast[ETH_ALEN] =
552                 { 0x09, 0x00, 0x07, 0xFF, 0xFF, 0xFF };
553         int hash;
554         struct aarp_entry *a;
555 
556         skb_reset_network_header(skb);
557 
558         /* Check for LocalTalk first */
559         if (dev->type == ARPHRD_LOCALTLK) {
560                 struct atalk_addr *at = atalk_find_dev_addr(dev);
561                 struct ddpehdr *ddp = (struct ddpehdr *)skb->data;
562                 int ft = 2;
563 
564                 /*
565                  * Compressible ?
566                  *
567                  * IFF: src_net == dest_net == device_net
568                  * (zero matches anything)
569                  */
570 
571                 if ((!ddp->deh_snet || at->s_net == ddp->deh_snet) &&
572                     (!ddp->deh_dnet || at->s_net == ddp->deh_dnet)) {
573                         skb_pull(skb, sizeof(*ddp) - 4);
574 
575                         /*
576                          *      The upper two remaining bytes are the port
577                          *      numbers we just happen to need. Now put the
578                          *      length in the lower two.
579                          */
580                         *((__be16 *)skb->data) = htons(skb->len);
581                         ft = 1;
582                 }
583                 /*
584                  * Nice and easy. No AARP type protocols occur here so we can
585                  * just shovel it out with a 3 byte LLAP header
586                  */
587 
588                 skb_push(skb, 3);
589                 skb->data[0] = sa->s_node;
590                 skb->data[1] = at->s_node;
591                 skb->data[2] = ft;
592                 skb->dev     = dev;
593                 goto sendit;
594         }
595 
596         /* On a PPP link we neither compress nor aarp.  */
597         if (dev->type == ARPHRD_PPP) {
598                 skb->protocol = htons(ETH_P_PPPTALK);
599                 skb->dev = dev;
600                 goto sendit;
601         }
602 
603         /* Non ELAP we cannot do. */
604         if (dev->type != ARPHRD_ETHER)
605                 goto free_it;
606 
607         skb->dev = dev;
608         skb->protocol = htons(ETH_P_ATALK);
609         hash = sa->s_node % (AARP_HASH_SIZE - 1);
610 
611         /* Do we have a resolved entry? */
612         if (sa->s_node == ATADDR_BCAST) {
613                 /* Send it */
614                 ddp_dl->request(ddp_dl, skb, ddp_eth_multicast);
615                 goto sent;
616         }
617 
618         write_lock_bh(&aarp_lock);
619         a = __aarp_find_entry(resolved[hash], dev, sa);
620 
621         if (a) { /* Return 1 and fill in the address */
622                 a->expires_at = jiffies + (sysctl_aarp_expiry_time * 10);
623                 ddp_dl->request(ddp_dl, skb, a->hwaddr);
624                 write_unlock_bh(&aarp_lock);
625                 goto sent;
626         }
627 
628         /* Do we have an unresolved entry: This is the less common path */
629         a = __aarp_find_entry(unresolved[hash], dev, sa);
630         if (a) { /* Queue onto the unresolved queue */
631                 skb_queue_tail(&a->packet_queue, skb);
632                 goto out_unlock;
633         }
634 
635         /* Allocate a new entry */
636         a = aarp_alloc();
637         if (!a) {
638                 /* Whoops slipped... good job it's an unreliable protocol 8) */
639                 write_unlock_bh(&aarp_lock);
640                 goto free_it;
641         }
642 
643         /* Set up the queue */
644         skb_queue_tail(&a->packet_queue, skb);
645         a->expires_at    = jiffies + sysctl_aarp_resolve_time;
646         a->dev           = dev;
647         a->next          = unresolved[hash];
648         a->target_addr   = *sa;
649         a->xmit_count    = 0;
650         unresolved[hash] = a;
651         unresolved_count++;
652 
653         /* Send an initial request for the address */
654         __aarp_send_query(a);
655 
656         /*
657          * Switch to fast timer if needed (That is if this is the first
658          * unresolved entry to get added)
659          */
660 
661         if (unresolved_count == 1)
662                 mod_timer(&aarp_timer, jiffies + sysctl_aarp_tick_time);
663 
664         /* Now finally, it is safe to drop the lock. */
665 out_unlock:
666         write_unlock_bh(&aarp_lock);
667 
668         /* Tell the ddp layer we have taken over for this frame. */
669         goto sent;
670 
671 sendit:
672         if (skb->sk)
673                 skb->priority = skb->sk->sk_priority;
674         if (dev_queue_xmit(skb))
675                 goto drop;
676 sent:
677         return NET_XMIT_SUCCESS;
678 free_it:
679         kfree_skb(skb);
680 drop:
681         return NET_XMIT_DROP;
682 }
683 EXPORT_SYMBOL(aarp_send_ddp);
684 
685 /*
686  *      An entry in the aarp unresolved queue has become resolved. Send
687  *      all the frames queued under it.
688  *
689  *      Must run under aarp_lock.
690  */
691 static void __aarp_resolved(struct aarp_entry **list, struct aarp_entry *a,
692                             int hash)
693 {
694         struct sk_buff *skb;
695 
696         while (*list)
697                 if (*list == a) {
698                         unresolved_count--;
699                         *list = a->next;
700 
701                         /* Move into the resolved list */
702                         a->next = resolved[hash];
703                         resolved[hash] = a;
704 
705                         /* Kick frames off */
706                         while ((skb = skb_dequeue(&a->packet_queue)) != NULL) {
707                                 a->expires_at = jiffies +
708                                                 sysctl_aarp_expiry_time * 10;
709                                 ddp_dl->request(ddp_dl, skb, a->hwaddr);
710                         }
711                 } else
712                         list = &((*list)->next);
713 }
714 
715 /*
716  *      This is called by the SNAP driver whenever we see an AARP SNAP
717  *      frame. We currently only support Ethernet.
718  */
719 static int aarp_rcv(struct sk_buff *skb, struct net_device *dev,
720                     struct packet_type *pt, struct net_device *orig_dev)
721 {
722         struct elapaarp *ea = aarp_hdr(skb);
723         int hash, ret = 0;
724         __u16 function;
725         struct aarp_entry *a;
726         struct atalk_addr sa, *ma, da;
727         struct atalk_iface *ifa;
728 
729         if (!net_eq(dev_net(dev), &init_net))
730                 goto out0;
731 
732         /* We only do Ethernet SNAP AARP. */
733         if (dev->type != ARPHRD_ETHER)
734                 goto out0;
735 
736         /* Frame size ok? */
737         if (!skb_pull(skb, sizeof(*ea)))
738                 goto out0;
739 
740         function = ntohs(ea->function);
741 
742         /* Sanity check fields. */
743         if (function < AARP_REQUEST || function > AARP_PROBE ||
744             ea->hw_len != ETH_ALEN || ea->pa_len != AARP_PA_ALEN ||
745             ea->pa_src_zero || ea->pa_dst_zero)
746                 goto out0;
747 
748         /* Looks good. */
749         hash = ea->pa_src_node % (AARP_HASH_SIZE - 1);
750 
751         /* Build an address. */
752         sa.s_node = ea->pa_src_node;
753         sa.s_net = ea->pa_src_net;
754 
755         /* Process the packet. Check for replies of me. */
756         ifa = atalk_find_dev(dev);
757         if (!ifa)
758                 goto out1;
759 
760         if (ifa->status & ATIF_PROBE &&
761             ifa->address.s_node == ea->pa_dst_node &&
762             ifa->address.s_net == ea->pa_dst_net) {
763                 ifa->status |= ATIF_PROBE_FAIL; /* Fail the probe (in use) */
764                 goto out1;
765         }
766 
767         /* Check for replies of proxy AARP entries */
768         da.s_node = ea->pa_dst_node;
769         da.s_net  = ea->pa_dst_net;
770 
771         write_lock_bh(&aarp_lock);
772         a = __aarp_find_entry(proxies[hash], dev, &da);
773 
774         if (a && a->status & ATIF_PROBE) {
775                 a->status |= ATIF_PROBE_FAIL;
776                 /*
777                  * we do not respond to probe or request packets for
778                  * this address while we are probing this address
779                  */
780                 goto unlock;
781         }
782 
783         switch (function) {
784         case AARP_REPLY:
785                 if (!unresolved_count)  /* Speed up */
786                         break;
787 
788                 /* Find the entry.  */
789                 a = __aarp_find_entry(unresolved[hash], dev, &sa);
790                 if (!a || dev != a->dev)
791                         break;
792 
793                 /* We can fill one in - this is good. */
794                 ether_addr_copy(a->hwaddr, ea->hw_src);
795                 __aarp_resolved(&unresolved[hash], a, hash);
796                 if (!unresolved_count)
797                         mod_timer(&aarp_timer,
798                                   jiffies + sysctl_aarp_expiry_time);
799                 break;
800 
801         case AARP_REQUEST:
802         case AARP_PROBE:
803 
804                 /*
805                  * If it is my address set ma to my address and reply.
806                  * We can treat probe and request the same.  Probe
807                  * simply means we shouldn't cache the querying host,
808                  * as in a probe they are proposing an address not
809                  * using one.
810                  *
811                  * Support for proxy-AARP added. We check if the
812                  * address is one of our proxies before we toss the
813                  * packet out.
814                  */
815 
816                 sa.s_node = ea->pa_dst_node;
817                 sa.s_net  = ea->pa_dst_net;
818 
819                 /* See if we have a matching proxy. */
820                 ma = __aarp_proxy_find(dev, &sa);
821                 if (!ma)
822                         ma = &ifa->address;
823                 else { /* We need to make a copy of the entry. */
824                         da.s_node = sa.s_node;
825                         da.s_net = sa.s_net;
826                         ma = &da;
827                 }
828 
829                 if (function == AARP_PROBE) {
830                         /*
831                          * A probe implies someone trying to get an
832                          * address. So as a precaution flush any
833                          * entries we have for this address.
834                          */
835                         a = __aarp_find_entry(resolved[sa.s_node %
836                                                        (AARP_HASH_SIZE - 1)],
837                                               skb->dev, &sa);
838 
839                         /*
840                          * Make it expire next tick - that avoids us
841                          * getting into a probe/flush/learn/probe/
842                          * flush/learn cycle during probing of a slow
843                          * to respond host addr.
844                          */
845                         if (a) {
846                                 a->expires_at = jiffies - 1;
847                                 mod_timer(&aarp_timer, jiffies +
848                                           sysctl_aarp_tick_time);
849                         }
850                 }
851 
852                 if (sa.s_node != ma->s_node)
853                         break;
854 
855                 if (sa.s_net && ma->s_net && sa.s_net != ma->s_net)
856                         break;
857 
858                 sa.s_node = ea->pa_src_node;
859                 sa.s_net = ea->pa_src_net;
860 
861                 /* aarp_my_address has found the address to use for us.
862                  */
863                 aarp_send_reply(dev, ma, &sa, ea->hw_src);
864                 break;
865         }
866 
867 unlock:
868         write_unlock_bh(&aarp_lock);
869 out1:
870         ret = 1;
871 out0:
872         kfree_skb(skb);
873         return ret;
874 }
875 
876 static struct notifier_block aarp_notifier = {
877         .notifier_call = aarp_device_event,
878 };
879 
880 static unsigned char aarp_snap_id[] = { 0x00, 0x00, 0x00, 0x80, 0xF3 };
881 
882 void __init aarp_proto_init(void)
883 {
884         aarp_dl = register_snap_client(aarp_snap_id, aarp_rcv);
885         if (!aarp_dl)
886                 printk(KERN_CRIT "Unable to register AARP with SNAP.\n");
887         timer_setup(&aarp_timer, aarp_expire_timeout, 0);
888         aarp_timer.expires  = jiffies + sysctl_aarp_expiry_time;
889         add_timer(&aarp_timer);
890         register_netdevice_notifier(&aarp_notifier);
891 }
892 
893 /* Remove the AARP entries associated with a device. */
894 void aarp_device_down(struct net_device *dev)
895 {
896         int ct;
897 
898         write_lock_bh(&aarp_lock);
899 
900         for (ct = 0; ct < AARP_HASH_SIZE; ct++) {
901                 __aarp_expire_device(&resolved[ct], dev);
902                 __aarp_expire_device(&unresolved[ct], dev);
903                 __aarp_expire_device(&proxies[ct], dev);
904         }
905 
906         write_unlock_bh(&aarp_lock);
907 }
908 
909 #ifdef CONFIG_PROC_FS
910 struct aarp_iter_state {
911         int bucket;
912         struct aarp_entry **table;
913 };
914 
915 /*
916  * Get the aarp entry that is in the chain described
917  * by the iterator.
918  * If pos is set then skip till that index.
919  * pos = 1 is the first entry
920  */
921 static struct aarp_entry *iter_next(struct aarp_iter_state *iter, loff_t *pos)
922 {
923         int ct = iter->bucket;
924         struct aarp_entry **table = iter->table;
925         loff_t off = 0;
926         struct aarp_entry *entry;
927 
928  rescan:
929         while (ct < AARP_HASH_SIZE) {
930                 for (entry = table[ct]; entry; entry = entry->next) {
931                         if (!pos || ++off == *pos) {
932                                 iter->table = table;
933                                 iter->bucket = ct;
934                                 return entry;
935                         }
936                 }
937                 ++ct;
938         }
939 
940         if (table == resolved) {
941                 ct = 0;
942                 table = unresolved;
943                 goto rescan;
944         }
945         if (table == unresolved) {
946                 ct = 0;
947                 table = proxies;
948                 goto rescan;
949         }
950         return NULL;
951 }
952 
953 static void *aarp_seq_start(struct seq_file *seq, loff_t *pos)
954         __acquires(aarp_lock)
955 {
956         struct aarp_iter_state *iter = seq->private;
957 
958         read_lock_bh(&aarp_lock);
959         iter->table     = resolved;
960         iter->bucket    = 0;
961 
962         return *pos ? iter_next(iter, pos) : SEQ_START_TOKEN;
963 }
964 
965 static void *aarp_seq_next(struct seq_file *seq, void *v, loff_t *pos)
966 {
967         struct aarp_entry *entry = v;
968         struct aarp_iter_state *iter = seq->private;
969 
970         ++*pos;
971 
972         /* first line after header */
973         if (v == SEQ_START_TOKEN)
974                 entry = iter_next(iter, NULL);
975 
976         /* next entry in current bucket */
977         else if (entry->next)
978                 entry = entry->next;
979 
980         /* next bucket or table */
981         else {
982                 ++iter->bucket;
983                 entry = iter_next(iter, NULL);
984         }
985         return entry;
986 }
987 
988 static void aarp_seq_stop(struct seq_file *seq, void *v)
989         __releases(aarp_lock)
990 {
991         read_unlock_bh(&aarp_lock);
992 }
993 
994 static const char *dt2str(unsigned long ticks)
995 {
996         static char buf[32];
997 
998         sprintf(buf, "%ld.%02ld", ticks / HZ, ((ticks % HZ) * 100) / HZ);
999 
1000         return buf;
1001 }
1002 
1003 static int aarp_seq_show(struct seq_file *seq, void *v)
1004 {
1005         struct aarp_iter_state *iter = seq->private;
1006         struct aarp_entry *entry = v;
1007         unsigned long now = jiffies;
1008 
1009         if (v == SEQ_START_TOKEN)
1010                 seq_puts(seq,
1011                          "Address  Interface   Hardware Address"
1012                          "   Expires LastSend  Retry Status\n");
1013         else {
1014                 seq_printf(seq, "%04X:%02X  %-12s",
1015                            ntohs(entry->target_addr.s_net),
1016                            (unsigned int) entry->target_addr.s_node,
1017                            entry->dev ? entry->dev->name : "????");
1018                 seq_printf(seq, "%pM", entry->hwaddr);
1019                 seq_printf(seq, " %8s",
1020                            dt2str((long)entry->expires_at - (long)now));
1021                 if (iter->table == unresolved)
1022                         seq_printf(seq, " %8s %6hu",
1023                                    dt2str(now - entry->last_sent),
1024                                    entry->xmit_count);
1025                 else
1026                         seq_puts(seq, "                ");
1027                 seq_printf(seq, " %s\n",
1028                            (iter->table == resolved) ? "resolved"
1029                            : (iter->table == unresolved) ? "unresolved"
1030                            : (iter->table == proxies) ? "proxies"
1031                            : "unknown");
1032         }
1033         return 0;
1034 }
1035 
1036 static const struct seq_operations aarp_seq_ops = {
1037         .start  = aarp_seq_start,
1038         .next   = aarp_seq_next,
1039         .stop   = aarp_seq_stop,
1040         .show   = aarp_seq_show,
1041 };
1042 
1043 static int aarp_seq_open(struct inode *inode, struct file *file)
1044 {
1045         return seq_open_private(file, &aarp_seq_ops,
1046                         sizeof(struct aarp_iter_state));
1047 }
1048 
1049 const struct file_operations atalk_seq_arp_fops = {
1050         .owner          = THIS_MODULE,
1051         .open           = aarp_seq_open,
1052         .read           = seq_read,
1053         .llseek         = seq_lseek,
1054         .release        = seq_release_private,
1055 };
1056 #endif
1057 
1058 /* General module cleanup. Called from cleanup_module() in ddp.c. */
1059 void aarp_cleanup_module(void)
1060 {
1061         del_timer_sync(&aarp_timer);
1062         unregister_netdevice_notifier(&aarp_notifier);
1063         unregister_snap_client(aarp_dl);
1064         aarp_purge();
1065 }
1066 

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