1 /*
2  * Linux ARCnet driver - RFC1201 (standard) packet encapsulation
3  *
4  * Written 1994-1999 by Avery Pennarun.
5  * Derived from skeleton.c by Donald Becker.
6  *
7  * Special thanks to Contemporary Controls, Inc. (www.ccontrols.com)
8  *  for sponsoring the further development of this driver.
9  *
10  * **********************
11  *
12  * The original copyright of skeleton.c was as follows:
13  *
14  * skeleton.c Written 1993 by Donald Becker.
15  * Copyright 1993 United States Government as represented by the
16  * Director, National Security Agency.  This software may only be used
17  * and distributed according to the terms of the GNU General Public License as
18  * modified by SRC, incorporated herein by reference.
19  *
20  * **********************
21  *
22  * For more details, see drivers/net/arcnet.c
23  *
24  * **********************
25  */
26 
27 #define pr_fmt(fmt) "arcnet:" KBUILD_MODNAME ": " fmt
28 
29 #include <linux/gfp.h>
30 #include <linux/module.h>
31 #include <linux/init.h>
32 #include <linux/if_arp.h>
33 #include <linux/netdevice.h>
34 #include <linux/skbuff.h>
35 
36 #include "arcdevice.h"
37 
38 MODULE_LICENSE("GPL");
39 
40 static __be16 type_trans(struct sk_buff *skb, struct net_device *dev);
41 static void rx(struct net_device *dev, int bufnum,
42 	       struct archdr *pkthdr, int length);
43 static int build_header(struct sk_buff *skb, struct net_device *dev,
44 			unsigned short type, uint8_t daddr);
45 static int prepare_tx(struct net_device *dev, struct archdr *pkt, int length,
46 		      int bufnum);
47 static int continue_tx(struct net_device *dev, int bufnum);
48 
49 static struct ArcProto rfc1201_proto = {
50 	.suffix		= 'a',
51 	.mtu		= 1500,	/* could be more, but some receivers can't handle it... */
52 	.is_ip          = 1,    /* This is for sending IP and ARP packages */
53 	.rx		= rx,
54 	.build_header	= build_header,
55 	.prepare_tx	= prepare_tx,
56 	.continue_tx	= continue_tx,
57 	.ack_tx         = NULL
58 };
59 
arcnet_rfc1201_init(void)60 static int __init arcnet_rfc1201_init(void)
61 {
62 	pr_info("%s\n", "RFC1201 \"standard\" (`a') encapsulation support loaded");
63 
64 	arc_proto_map[ARC_P_IP]
65 	    = arc_proto_map[ARC_P_IPV6]
66 	    = arc_proto_map[ARC_P_ARP]
67 	    = arc_proto_map[ARC_P_RARP]
68 	    = arc_proto_map[ARC_P_IPX]
69 	    = arc_proto_map[ARC_P_NOVELL_EC]
70 	    = &rfc1201_proto;
71 
72 	/* if someone else already owns the broadcast, we won't take it */
73 	if (arc_bcast_proto == arc_proto_default)
74 		arc_bcast_proto = &rfc1201_proto;
75 
76 	return 0;
77 }
78 
arcnet_rfc1201_exit(void)79 static void __exit arcnet_rfc1201_exit(void)
80 {
81 	arcnet_unregister_proto(&rfc1201_proto);
82 }
83 
84 module_init(arcnet_rfc1201_init);
85 module_exit(arcnet_rfc1201_exit);
86 
87 /* Determine a packet's protocol ID.
88  *
89  * With ARCnet we have to convert everything to Ethernet-style stuff.
90  */
type_trans(struct sk_buff * skb,struct net_device * dev)91 static __be16 type_trans(struct sk_buff *skb, struct net_device *dev)
92 {
93 	struct archdr *pkt = (struct archdr *)skb->data;
94 	struct arc_rfc1201 *soft = &pkt->soft.rfc1201;
95 	int hdr_size = ARC_HDR_SIZE + RFC1201_HDR_SIZE;
96 
97 	/* Pull off the arcnet header. */
98 	skb_reset_mac_header(skb);
99 	skb_pull(skb, hdr_size);
100 
101 	if (pkt->hard.dest == 0) {
102 		skb->pkt_type = PACKET_BROADCAST;
103 	} else if (dev->flags & IFF_PROMISC) {
104 		/* if we're not sending to ourselves :) */
105 		if (pkt->hard.dest != dev->dev_addr[0])
106 			skb->pkt_type = PACKET_OTHERHOST;
107 	}
108 	/* now return the protocol number */
109 	switch (soft->proto) {
110 	case ARC_P_IP:
111 		return htons(ETH_P_IP);
112 	case ARC_P_IPV6:
113 		return htons(ETH_P_IPV6);
114 	case ARC_P_ARP:
115 		return htons(ETH_P_ARP);
116 	case ARC_P_RARP:
117 		return htons(ETH_P_RARP);
118 
119 	case ARC_P_IPX:
120 	case ARC_P_NOVELL_EC:
121 		return htons(ETH_P_802_3);
122 	default:
123 		dev->stats.rx_errors++;
124 		dev->stats.rx_crc_errors++;
125 		return 0;
126 	}
127 
128 	return htons(ETH_P_IP);
129 }
130 
131 /* packet receiver */
rx(struct net_device * dev,int bufnum,struct archdr * pkthdr,int length)132 static void rx(struct net_device *dev, int bufnum,
133 	       struct archdr *pkthdr, int length)
134 {
135 	struct arcnet_local *lp = netdev_priv(dev);
136 	struct sk_buff *skb;
137 	struct archdr *pkt = pkthdr;
138 	struct arc_rfc1201 *soft = &pkthdr->soft.rfc1201;
139 	int saddr = pkt->hard.source, ofs;
140 	struct Incoming *in = &lp->rfc1201.incoming[saddr];
141 
142 	arc_printk(D_DURING, dev, "it's an RFC1201 packet (length=%d)\n",
143 		   length);
144 
145 	if (length >= MinTU)
146 		ofs = 512 - length;
147 	else
148 		ofs = 256 - length;
149 
150 	if (soft->split_flag == 0xFF) {		/* Exception Packet */
151 		if (length >= 4 + RFC1201_HDR_SIZE) {
152 			arc_printk(D_DURING, dev, "compensating for exception packet\n");
153 		} else {
154 			arc_printk(D_EXTRA, dev, "short RFC1201 exception packet from %02Xh",
155 				   saddr);
156 			return;
157 		}
158 
159 		/* skip over 4-byte junkola */
160 		length -= 4;
161 		ofs += 4;
162 		lp->hw.copy_from_card(dev, bufnum, 512 - length,
163 				      soft, sizeof(pkt->soft));
164 	}
165 	if (!soft->split_flag) {	/* not split */
166 		arc_printk(D_RX, dev, "incoming is not split (splitflag=%d)\n",
167 			   soft->split_flag);
168 
169 		if (in->skb) {	/* already assembling one! */
170 			arc_printk(D_EXTRA, dev, "aborting assembly (seq=%d) for unsplit packet (splitflag=%d, seq=%d)\n",
171 				   in->sequence, soft->split_flag,
172 				   soft->sequence);
173 			lp->rfc1201.aborted_seq = soft->sequence;
174 			dev_kfree_skb_irq(in->skb);
175 			dev->stats.rx_errors++;
176 			dev->stats.rx_missed_errors++;
177 			in->skb = NULL;
178 		}
179 		in->sequence = soft->sequence;
180 
181 		skb = alloc_skb(length + ARC_HDR_SIZE, GFP_ATOMIC);
182 		if (!skb) {
183 			dev->stats.rx_dropped++;
184 			return;
185 		}
186 		skb_put(skb, length + ARC_HDR_SIZE);
187 		skb->dev = dev;
188 
189 		pkt = (struct archdr *)skb->data;
190 		soft = &pkt->soft.rfc1201;
191 
192 		/* up to sizeof(pkt->soft) has already
193 		 * been copied from the card
194 		 */
195 		memcpy(pkt, pkthdr, sizeof(struct archdr));
196 		if (length > sizeof(pkt->soft))
197 			lp->hw.copy_from_card(dev, bufnum,
198 					      ofs + sizeof(pkt->soft),
199 					      pkt->soft.raw + sizeof(pkt->soft),
200 					      length - sizeof(pkt->soft));
201 
202 		/* ARP packets have problems when sent from some DOS systems:
203 		 * the source address is always 0!
204 		 * So we take the hardware source addr (which is impossible
205 		 * to fumble) and insert it ourselves.
206 		 */
207 		if (soft->proto == ARC_P_ARP) {
208 			struct arphdr *arp = (struct arphdr *)soft->payload;
209 
210 			/* make sure addresses are the right length */
211 			if (arp->ar_hln == 1 && arp->ar_pln == 4) {
212 				uint8_t *cptr = (uint8_t *)arp + sizeof(struct arphdr);
213 
214 				if (!*cptr) {	/* is saddr = 00? */
215 					arc_printk(D_EXTRA, dev,
216 						   "ARP source address was 00h, set to %02Xh\n",
217 						   saddr);
218 					dev->stats.rx_crc_errors++;
219 					*cptr = saddr;
220 				} else {
221 					arc_printk(D_DURING, dev, "ARP source address (%Xh) is fine.\n",
222 						   *cptr);
223 				}
224 			} else {
225 				arc_printk(D_NORMAL, dev, "funny-shaped ARP packet. (%Xh, %Xh)\n",
226 					   arp->ar_hln, arp->ar_pln);
227 				dev->stats.rx_errors++;
228 				dev->stats.rx_crc_errors++;
229 			}
230 		}
231 		if (BUGLVL(D_SKB))
232 			arcnet_dump_skb(dev, skb, "rx");
233 
234 		skb->protocol = type_trans(skb, dev);
235 		netif_rx(skb);
236 	} else {		/* split packet */
237 		/* NOTE: MSDOS ARP packet correction should only need to
238 		 * apply to unsplit packets, since ARP packets are so short.
239 		 *
240 		 * My interpretation of the RFC1201 document is that if a
241 		 * packet is received out of order, the entire assembly
242 		 * process should be aborted.
243 		 *
244 		 * The RFC also mentions "it is possible for successfully
245 		 * received packets to be retransmitted." As of 0.40 all
246 		 * previously received packets are allowed, not just the
247 		 * most recent one.
248 		 *
249 		 * We allow multiple assembly processes, one for each
250 		 * ARCnet card possible on the network.
251 		 * Seems rather like a waste of memory, but there's no
252 		 * other way to be reliable.
253 		 */
254 
255 		arc_printk(D_RX, dev, "packet is split (splitflag=%d, seq=%d)\n",
256 			   soft->split_flag, in->sequence);
257 
258 		if (in->skb && in->sequence != soft->sequence) {
259 			arc_printk(D_EXTRA, dev, "wrong seq number (saddr=%d, expected=%d, seq=%d, splitflag=%d)\n",
260 				   saddr, in->sequence, soft->sequence,
261 				   soft->split_flag);
262 			dev_kfree_skb_irq(in->skb);
263 			in->skb = NULL;
264 			dev->stats.rx_errors++;
265 			dev->stats.rx_missed_errors++;
266 			in->lastpacket = in->numpackets = 0;
267 		}
268 		if (soft->split_flag & 1) {	/* first packet in split */
269 			arc_printk(D_RX, dev, "brand new splitpacket (splitflag=%d)\n",
270 				   soft->split_flag);
271 			if (in->skb) {	/* already assembling one! */
272 				arc_printk(D_EXTRA, dev, "aborting previous (seq=%d) assembly (splitflag=%d, seq=%d)\n",
273 					   in->sequence, soft->split_flag,
274 					   soft->sequence);
275 				dev->stats.rx_errors++;
276 				dev->stats.rx_missed_errors++;
277 				dev_kfree_skb_irq(in->skb);
278 			}
279 			in->sequence = soft->sequence;
280 			in->numpackets = ((unsigned)soft->split_flag >> 1) + 2;
281 			in->lastpacket = 1;
282 
283 			if (in->numpackets > 16) {
284 				arc_printk(D_EXTRA, dev, "incoming packet more than 16 segments; dropping. (splitflag=%d)\n",
285 					   soft->split_flag);
286 				lp->rfc1201.aborted_seq = soft->sequence;
287 				dev->stats.rx_errors++;
288 				dev->stats.rx_length_errors++;
289 				return;
290 			}
291 			in->skb = skb = alloc_skb(508 * in->numpackets + ARC_HDR_SIZE,
292 						  GFP_ATOMIC);
293 			if (!skb) {
294 				arc_printk(D_NORMAL, dev, "(split) memory squeeze, dropping packet.\n");
295 				lp->rfc1201.aborted_seq = soft->sequence;
296 				dev->stats.rx_dropped++;
297 				return;
298 			}
299 			skb->dev = dev;
300 			pkt = (struct archdr *)skb->data;
301 			soft = &pkt->soft.rfc1201;
302 
303 			memcpy(pkt, pkthdr, ARC_HDR_SIZE + RFC1201_HDR_SIZE);
304 			skb_put(skb, ARC_HDR_SIZE + RFC1201_HDR_SIZE);
305 
306 			soft->split_flag = 0;	/* end result won't be split */
307 		} else {	/* not first packet */
308 			int packetnum = ((unsigned)soft->split_flag >> 1) + 1;
309 
310 			/* if we're not assembling, there's no point trying to
311 			 * continue.
312 			 */
313 			if (!in->skb) {
314 				if (lp->rfc1201.aborted_seq != soft->sequence) {
315 					arc_printk(D_EXTRA, dev, "can't continue split without starting first! (splitflag=%d, seq=%d, aborted=%d)\n",
316 						   soft->split_flag,
317 						   soft->sequence,
318 						   lp->rfc1201.aborted_seq);
319 					dev->stats.rx_errors++;
320 					dev->stats.rx_missed_errors++;
321 				}
322 				return;
323 			}
324 			in->lastpacket++;
325 			/* if not the right flag */
326 			if (packetnum != in->lastpacket) {
327 				/* harmless duplicate? ignore. */
328 				if (packetnum <= in->lastpacket - 1) {
329 					arc_printk(D_EXTRA, dev, "duplicate splitpacket ignored! (splitflag=%d)\n",
330 						   soft->split_flag);
331 					dev->stats.rx_errors++;
332 					dev->stats.rx_frame_errors++;
333 					return;
334 				}
335 				/* "bad" duplicate, kill reassembly */
336 				arc_printk(D_EXTRA, dev, "out-of-order splitpacket, reassembly (seq=%d) aborted (splitflag=%d, seq=%d)\n",
337 					   in->sequence, soft->split_flag,
338 					   soft->sequence);
339 				lp->rfc1201.aborted_seq = soft->sequence;
340 				dev_kfree_skb_irq(in->skb);
341 				in->skb = NULL;
342 				dev->stats.rx_errors++;
343 				dev->stats.rx_missed_errors++;
344 				in->lastpacket = in->numpackets = 0;
345 				return;
346 			}
347 			pkt = (struct archdr *)in->skb->data;
348 			soft = &pkt->soft.rfc1201;
349 		}
350 
351 		skb = in->skb;
352 
353 		lp->hw.copy_from_card(dev, bufnum, ofs + RFC1201_HDR_SIZE,
354 				      skb->data + skb->len,
355 				      length - RFC1201_HDR_SIZE);
356 		skb_put(skb, length - RFC1201_HDR_SIZE);
357 
358 		/* are we done? */
359 		if (in->lastpacket == in->numpackets) {
360 			in->skb = NULL;
361 			in->lastpacket = in->numpackets = 0;
362 
363 			arc_printk(D_SKB_SIZE, dev, "skb: received %d bytes from %02X (unsplit)\n",
364 				   skb->len, pkt->hard.source);
365 			arc_printk(D_SKB_SIZE, dev, "skb: received %d bytes from %02X (split)\n",
366 				   skb->len, pkt->hard.source);
367 			if (BUGLVL(D_SKB))
368 				arcnet_dump_skb(dev, skb, "rx");
369 
370 			skb->protocol = type_trans(skb, dev);
371 			netif_rx(skb);
372 		}
373 	}
374 }
375 
376 /* Create the ARCnet hard/soft headers for RFC1201. */
build_header(struct sk_buff * skb,struct net_device * dev,unsigned short type,uint8_t daddr)377 static int build_header(struct sk_buff *skb, struct net_device *dev,
378 			unsigned short type, uint8_t daddr)
379 {
380 	struct arcnet_local *lp = netdev_priv(dev);
381 	int hdr_size = ARC_HDR_SIZE + RFC1201_HDR_SIZE;
382 	struct archdr *pkt = skb_push(skb, hdr_size);
383 	struct arc_rfc1201 *soft = &pkt->soft.rfc1201;
384 
385 	/* set the protocol ID according to RFC1201 */
386 	switch (type) {
387 	case ETH_P_IP:
388 		soft->proto = ARC_P_IP;
389 		break;
390 	case ETH_P_IPV6:
391 		soft->proto = ARC_P_IPV6;
392 		break;
393 	case ETH_P_ARP:
394 		soft->proto = ARC_P_ARP;
395 		break;
396 	case ETH_P_RARP:
397 		soft->proto = ARC_P_RARP;
398 		break;
399 	case ETH_P_IPX:
400 	case ETH_P_802_3:
401 	case ETH_P_802_2:
402 		soft->proto = ARC_P_IPX;
403 		break;
404 	case ETH_P_ATALK:
405 		soft->proto = ARC_P_ATALK;
406 		break;
407 	default:
408 		arc_printk(D_NORMAL, dev, "RFC1201: I don't understand protocol %d (%Xh)\n",
409 			   type, type);
410 		dev->stats.tx_errors++;
411 		dev->stats.tx_aborted_errors++;
412 		return 0;
413 	}
414 
415 	/* Set the source hardware address.
416 	 *
417 	 * This is pretty pointless for most purposes, but it can help in
418 	 * debugging.  ARCnet does not allow us to change the source address
419 	 * in the actual packet sent.
420 	 */
421 	pkt->hard.source = *dev->dev_addr;
422 
423 	soft->sequence = htons(lp->rfc1201.sequence++);
424 	soft->split_flag = 0;	/* split packets are done elsewhere */
425 
426 	/* see linux/net/ethernet/eth.c to see where I got the following */
427 
428 	if (dev->flags & (IFF_LOOPBACK | IFF_NOARP)) {
429 		/* FIXME: fill in the last byte of the dest ipaddr here
430 		 * to better comply with RFC1051 in "noarp" mode.
431 		 * For now, always broadcasting will probably at least get
432 		 * packets sent out :)
433 		 */
434 		pkt->hard.dest = 0;
435 		return hdr_size;
436 	}
437 	/* otherwise, drop in the dest address */
438 	pkt->hard.dest = daddr;
439 	return hdr_size;
440 }
441 
load_pkt(struct net_device * dev,struct arc_hardware * hard,struct arc_rfc1201 * soft,int softlen,int bufnum)442 static void load_pkt(struct net_device *dev, struct arc_hardware *hard,
443 		     struct arc_rfc1201 *soft, int softlen, int bufnum)
444 {
445 	struct arcnet_local *lp = netdev_priv(dev);
446 	int ofs;
447 
448 	/* assume length <= XMTU: someone should have handled that by now. */
449 
450 	if (softlen > MinTU) {
451 		hard->offset[0] = 0;
452 		hard->offset[1] = ofs = 512 - softlen;
453 	} else if (softlen > MTU) {	/* exception packet - add an extra header */
454 		struct arc_rfc1201 excsoft;
455 
456 		excsoft.proto = soft->proto;
457 		excsoft.split_flag = 0xff;
458 		excsoft.sequence = htons(0xffff);
459 
460 		hard->offset[0] = 0;
461 		ofs = 512 - softlen;
462 		hard->offset[1] = ofs - RFC1201_HDR_SIZE;
463 		lp->hw.copy_to_card(dev, bufnum, ofs - RFC1201_HDR_SIZE,
464 				    &excsoft, RFC1201_HDR_SIZE);
465 	} else {
466 		hard->offset[0] = ofs = 256 - softlen;
467 	}
468 
469 	lp->hw.copy_to_card(dev, bufnum, 0, hard, ARC_HDR_SIZE);
470 	lp->hw.copy_to_card(dev, bufnum, ofs, soft, softlen);
471 
472 	lp->lastload_dest = hard->dest;
473 }
474 
prepare_tx(struct net_device * dev,struct archdr * pkt,int length,int bufnum)475 static int prepare_tx(struct net_device *dev, struct archdr *pkt, int length,
476 		      int bufnum)
477 {
478 	struct arcnet_local *lp = netdev_priv(dev);
479 	const int maxsegsize = XMTU - RFC1201_HDR_SIZE;
480 	struct Outgoing *out;
481 
482 	arc_printk(D_DURING, dev, "prepare_tx: txbufs=%d/%d/%d\n",
483 		   lp->next_tx, lp->cur_tx, bufnum);
484 
485 	/* hard header is not included in packet length */
486 	length -= ARC_HDR_SIZE;
487 	pkt->soft.rfc1201.split_flag = 0;
488 
489 	/* need to do a split packet? */
490 	if (length > XMTU) {
491 		out = &lp->outgoing;
492 
493 		out->length = length - RFC1201_HDR_SIZE;
494 		out->dataleft = lp->outgoing.length;
495 		out->numsegs = (out->dataleft + maxsegsize - 1) / maxsegsize;
496 		out->segnum = 0;
497 
498 		arc_printk(D_DURING, dev, "rfc1201 prep_tx: ready for %d-segment split (%d bytes, seq=%d)\n",
499 			   out->numsegs, out->length,
500 			   pkt->soft.rfc1201.sequence);
501 
502 		return 0;	/* not done */
503 	}
504 	/* just load the packet into the buffers and send it off */
505 	load_pkt(dev, &pkt->hard, &pkt->soft.rfc1201, length, bufnum);
506 
507 	return 1;		/* done */
508 }
509 
continue_tx(struct net_device * dev,int bufnum)510 static int continue_tx(struct net_device *dev, int bufnum)
511 {
512 	struct arcnet_local *lp = netdev_priv(dev);
513 	struct Outgoing *out = &lp->outgoing;
514 	struct arc_hardware *hard = &out->pkt->hard;
515 	struct arc_rfc1201 *soft = &out->pkt->soft.rfc1201, *newsoft;
516 	int maxsegsize = XMTU - RFC1201_HDR_SIZE;
517 	int seglen;
518 
519 	arc_printk(D_DURING, dev,
520 		   "rfc1201 continue_tx: loading segment %d(+1) of %d (seq=%d)\n",
521 		   out->segnum, out->numsegs, soft->sequence);
522 
523 	/* the "new" soft header comes right before the data chunk */
524 	newsoft = (struct arc_rfc1201 *)
525 	    (out->pkt->soft.raw + out->length - out->dataleft);
526 
527 	if (!out->segnum)	/* first packet; newsoft == soft */
528 		newsoft->split_flag = ((out->numsegs - 2) << 1) | 1;
529 	else {
530 		newsoft->split_flag = out->segnum << 1;
531 		newsoft->proto = soft->proto;
532 		newsoft->sequence = soft->sequence;
533 	}
534 
535 	seglen = maxsegsize;
536 	if (seglen > out->dataleft)
537 		seglen = out->dataleft;
538 	out->dataleft -= seglen;
539 
540 	load_pkt(dev, hard, newsoft, seglen + RFC1201_HDR_SIZE, bufnum);
541 
542 	out->segnum++;
543 	if (out->segnum >= out->numsegs)
544 		return 1;
545 	else
546 		return 0;
547 }
548