xref: /linux/net/caif/cfpkt_skbuff.c (revision 5d4a2e29fba5b2bef95b96a46b338ec4d76fa4fd) 
1 /*
2  * Copyright (C) ST-Ericsson AB 2010
3  * Author:	Sjur Brendeland/sjur.brandeland@stericsson.com
4  * License terms: GNU General Public License (GPL) version 2
5  */
6 
7 #include <linux/string.h>
8 #include <linux/skbuff.h>
9 #include <linux/hardirq.h>
10 #include <net/caif/cfpkt.h>
11 
12 #define PKT_PREFIX CAIF_NEEDED_HEADROOM
13 #define PKT_POSTFIX CAIF_NEEDED_TAILROOM
14 #define PKT_LEN_WHEN_EXTENDING 128
15 #define PKT_ERROR(pkt, errmsg) do {	   \
16     cfpkt_priv(pkt)->erronous = true;	   \
17     skb_reset_tail_pointer(&pkt->skb);	   \
18     pr_warning("CAIF: " errmsg);\
19   } while (0)
20 
21 struct cfpktq {
22 	struct sk_buff_head head;
23 	atomic_t count;
24 	/* Lock protects count updates */
25 	spinlock_t lock;
26 };
27 
28 /*
29  * net/caif/ is generic and does not
30  * understand SKB, so we do this typecast
31  */
32 struct cfpkt {
33 	struct sk_buff skb;
34 };
35 
36 /* Private data inside SKB */
37 struct cfpkt_priv_data {
38 	struct dev_info dev_info;
39 	bool erronous;
40 };
41 
42 inline struct cfpkt_priv_data *cfpkt_priv(struct cfpkt *pkt)
43 {
44 	return (struct cfpkt_priv_data *) pkt->skb.cb;
45 }
46 
47 inline bool is_erronous(struct cfpkt *pkt)
48 {
49 	return cfpkt_priv(pkt)->erronous;
50 }
51 
52 inline struct sk_buff *pkt_to_skb(struct cfpkt *pkt)
53 {
54 	return &pkt->skb;
55 }
56 
57 inline struct cfpkt *skb_to_pkt(struct sk_buff *skb)
58 {
59 	return (struct cfpkt *) skb;
60 }
61 
62 
63 struct cfpkt *cfpkt_fromnative(enum caif_direction dir, void *nativepkt)
64 {
65 	struct cfpkt *pkt = skb_to_pkt(nativepkt);
66 	cfpkt_priv(pkt)->erronous = false;
67 	return pkt;
68 }
69 EXPORT_SYMBOL(cfpkt_fromnative);
70 
71 void *cfpkt_tonative(struct cfpkt *pkt)
72 {
73 	return (void *) pkt;
74 }
75 EXPORT_SYMBOL(cfpkt_tonative);
76 
77 static struct cfpkt *cfpkt_create_pfx(u16 len, u16 pfx)
78 {
79 	struct sk_buff *skb;
80 
81 	if (likely(in_interrupt()))
82 		skb = alloc_skb(len + pfx, GFP_ATOMIC);
83 	else
84 		skb = alloc_skb(len + pfx, GFP_KERNEL);
85 
86 	if (unlikely(skb == NULL))
87 		return NULL;
88 
89 	skb_reserve(skb, pfx);
90 	return skb_to_pkt(skb);
91 }
92 
93 inline struct cfpkt *cfpkt_create(u16 len)
94 {
95 	return cfpkt_create_pfx(len + PKT_POSTFIX, PKT_PREFIX);
96 }
97 EXPORT_SYMBOL(cfpkt_create);
98 
99 void cfpkt_destroy(struct cfpkt *pkt)
100 {
101 	struct sk_buff *skb = pkt_to_skb(pkt);
102 	kfree_skb(skb);
103 }
104 EXPORT_SYMBOL(cfpkt_destroy);
105 
106 inline bool cfpkt_more(struct cfpkt *pkt)
107 {
108 	struct sk_buff *skb = pkt_to_skb(pkt);
109 	return skb->len > 0;
110 }
111 EXPORT_SYMBOL(cfpkt_more);
112 
113 int cfpkt_peek_head(struct cfpkt *pkt, void *data, u16 len)
114 {
115 	struct sk_buff *skb = pkt_to_skb(pkt);
116 	if (skb_headlen(skb) >= len) {
117 		memcpy(data, skb->data, len);
118 		return 0;
119 	}
120 	return !cfpkt_extr_head(pkt, data, len) &&
121 	    !cfpkt_add_head(pkt, data, len);
122 }
123 EXPORT_SYMBOL(cfpkt_peek_head);
124 
125 int cfpkt_extr_head(struct cfpkt *pkt, void *data, u16 len)
126 {
127 	struct sk_buff *skb = pkt_to_skb(pkt);
128 	u8 *from;
129 	if (unlikely(is_erronous(pkt)))
130 		return -EPROTO;
131 
132 	if (unlikely(len > skb->len)) {
133 		PKT_ERROR(pkt, "cfpkt_extr_head read beyond end of packet\n");
134 		return -EPROTO;
135 	}
136 
137 	if (unlikely(len > skb_headlen(skb))) {
138 		if (unlikely(skb_linearize(skb) != 0)) {
139 			PKT_ERROR(pkt, "cfpkt_extr_head linearize failed\n");
140 			return -EPROTO;
141 		}
142 	}
143 	from = skb_pull(skb, len);
144 	from -= len;
145 	memcpy(data, from, len);
146 	return 0;
147 }
148 EXPORT_SYMBOL(cfpkt_extr_head);
149 
150 int cfpkt_extr_trail(struct cfpkt *pkt, void *dta, u16 len)
151 {
152 	struct sk_buff *skb = pkt_to_skb(pkt);
153 	u8 *data = dta;
154 	u8 *from;
155 	if (unlikely(is_erronous(pkt)))
156 		return -EPROTO;
157 
158 	if (unlikely(skb_linearize(skb) != 0)) {
159 		PKT_ERROR(pkt, "cfpkt_extr_trail linearize failed\n");
160 		return -EPROTO;
161 	}
162 	if (unlikely(skb->data + len > skb_tail_pointer(skb))) {
163 		PKT_ERROR(pkt, "cfpkt_extr_trail read beyond end of packet\n");
164 		return -EPROTO;
165 	}
166 	from = skb_tail_pointer(skb) - len;
167 	skb_trim(skb, skb->len - len);
168 	memcpy(data, from, len);
169 	return 0;
170 }
171 EXPORT_SYMBOL(cfpkt_extr_trail);
172 
173 int cfpkt_pad_trail(struct cfpkt *pkt, u16 len)
174 {
175 	return cfpkt_add_body(pkt, NULL, len);
176 }
177 EXPORT_SYMBOL(cfpkt_pad_trail);
178 
179 int cfpkt_add_body(struct cfpkt *pkt, const void *data, u16 len)
180 {
181 	struct sk_buff *skb = pkt_to_skb(pkt);
182 	struct sk_buff *lastskb;
183 	u8 *to;
184 	u16 addlen = 0;
185 
186 
187 	if (unlikely(is_erronous(pkt)))
188 		return -EPROTO;
189 
190 	lastskb = skb;
191 
192 	/* Check whether we need to add space at the tail */
193 	if (unlikely(skb_tailroom(skb) < len)) {
194 		if (likely(len < PKT_LEN_WHEN_EXTENDING))
195 			addlen = PKT_LEN_WHEN_EXTENDING;
196 		else
197 			addlen = len;
198 	}
199 
200 	/* Check whether we need to change the SKB before writing to the tail */
201 	if (unlikely((addlen > 0) || skb_cloned(skb) || skb_shared(skb))) {
202 
203 		/* Make sure data is writable */
204 		if (unlikely(skb_cow_data(skb, addlen, &lastskb) < 0)) {
205 			PKT_ERROR(pkt, "cfpkt_add_body: cow failed\n");
206 			return -EPROTO;
207 		}
208 		/*
209 		 * Is the SKB non-linear after skb_cow_data()? If so, we are
210 		 * going to add data to the last SKB, so we need to adjust
211 		 * lengths of the top SKB.
212 		 */
213 		if (lastskb != skb) {
214 			pr_warning("CAIF: %s(): Packet is non-linear\n",
215 				   __func__);
216 			skb->len += len;
217 			skb->data_len += len;
218 		}
219 	}
220 
221 	/* All set to put the last SKB and optionally write data there. */
222 	to = skb_put(lastskb, len);
223 	if (likely(data))
224 		memcpy(to, data, len);
225 	return 0;
226 }
227 EXPORT_SYMBOL(cfpkt_add_body);
228 
229 inline int cfpkt_addbdy(struct cfpkt *pkt, u8 data)
230 {
231 	return cfpkt_add_body(pkt, &data, 1);
232 }
233 EXPORT_SYMBOL(cfpkt_addbdy);
234 
235 int cfpkt_add_head(struct cfpkt *pkt, const void *data2, u16 len)
236 {
237 	struct sk_buff *skb = pkt_to_skb(pkt);
238 	struct sk_buff *lastskb;
239 	u8 *to;
240 	const u8 *data = data2;
241 	int ret;
242 	if (unlikely(is_erronous(pkt)))
243 		return -EPROTO;
244 	if (unlikely(skb_headroom(skb) < len)) {
245 		PKT_ERROR(pkt, "cfpkt_add_head: no headroom\n");
246 		return -EPROTO;
247 	}
248 
249 	/* Make sure data is writable */
250 	ret = skb_cow_data(skb, 0, &lastskb);
251 	if (unlikely(ret < 0)) {
252 		PKT_ERROR(pkt, "cfpkt_add_head: cow failed\n");
253 		return ret;
254 	}
255 
256 	to = skb_push(skb, len);
257 	memcpy(to, data, len);
258 	return 0;
259 }
260 EXPORT_SYMBOL(cfpkt_add_head);
261 
262 inline int cfpkt_add_trail(struct cfpkt *pkt, const void *data, u16 len)
263 {
264 	return cfpkt_add_body(pkt, data, len);
265 }
266 EXPORT_SYMBOL(cfpkt_add_trail);
267 
268 inline u16 cfpkt_getlen(struct cfpkt *pkt)
269 {
270 	struct sk_buff *skb = pkt_to_skb(pkt);
271 	return skb->len;
272 }
273 EXPORT_SYMBOL(cfpkt_getlen);
274 
275 inline u16 cfpkt_iterate(struct cfpkt *pkt,
276 			    u16 (*iter_func)(u16, void *, u16),
277 			    u16 data)
278 {
279 	/*
280 	 * Don't care about the performance hit of linearizing,
281 	 * Checksum should not be used on high-speed interfaces anyway.
282 	 */
283 	if (unlikely(is_erronous(pkt)))
284 		return -EPROTO;
285 	if (unlikely(skb_linearize(&pkt->skb) != 0)) {
286 		PKT_ERROR(pkt, "cfpkt_iterate: linearize failed\n");
287 		return -EPROTO;
288 	}
289 	return iter_func(data, pkt->skb.data, cfpkt_getlen(pkt));
290 }
291 EXPORT_SYMBOL(cfpkt_iterate);
292 
293 int cfpkt_setlen(struct cfpkt *pkt, u16 len)
294 {
295 	struct sk_buff *skb = pkt_to_skb(pkt);
296 
297 
298 	if (unlikely(is_erronous(pkt)))
299 		return -EPROTO;
300 
301 	if (likely(len <= skb->len)) {
302 		if (unlikely(skb->data_len))
303 			___pskb_trim(skb, len);
304 		else
305 			skb_trim(skb, len);
306 
307 			return cfpkt_getlen(pkt);
308 	}
309 
310 	/* Need to expand SKB */
311 	if (unlikely(!cfpkt_pad_trail(pkt, len - skb->len)))
312 		PKT_ERROR(pkt, "cfpkt_setlen: skb_pad_trail failed\n");
313 
314 	return cfpkt_getlen(pkt);
315 }
316 EXPORT_SYMBOL(cfpkt_setlen);
317 
318 struct cfpkt *cfpkt_create_uplink(const unsigned char *data, unsigned int len)
319 {
320 	struct cfpkt *pkt = cfpkt_create_pfx(len + PKT_POSTFIX, PKT_PREFIX);
321 	if (!pkt)
322 		return NULL;
323 	if (unlikely(data != NULL))
324 		cfpkt_add_body(pkt, data, len);
325 	return pkt;
326 }
327 EXPORT_SYMBOL(cfpkt_create_uplink);
328 
329 struct cfpkt *cfpkt_append(struct cfpkt *dstpkt,
330 			     struct cfpkt *addpkt,
331 			     u16 expectlen)
332 {
333 	struct sk_buff *dst = pkt_to_skb(dstpkt);
334 	struct sk_buff *add = pkt_to_skb(addpkt);
335 	u16 addlen = skb_headlen(add);
336 	u16 neededtailspace;
337 	struct sk_buff *tmp;
338 	u16 dstlen;
339 	u16 createlen;
340 	if (unlikely(is_erronous(dstpkt) || is_erronous(addpkt))) {
341 		cfpkt_destroy(addpkt);
342 		return dstpkt;
343 	}
344 	if (expectlen > addlen)
345 		neededtailspace = expectlen;
346 	else
347 		neededtailspace = addlen;
348 
349 	if (dst->tail + neededtailspace > dst->end) {
350 		/* Create a dumplicate of 'dst' with more tail space */
351 		struct cfpkt *tmppkt;
352 		dstlen = skb_headlen(dst);
353 		createlen = dstlen + neededtailspace;
354 		tmppkt = cfpkt_create(createlen + PKT_PREFIX + PKT_POSTFIX);
355 		if (tmppkt == NULL)
356 			return NULL;
357 		tmp = pkt_to_skb(tmppkt);
358 		skb_set_tail_pointer(tmp, dstlen);
359 		tmp->len = dstlen;
360 		memcpy(tmp->data, dst->data, dstlen);
361 		cfpkt_destroy(dstpkt);
362 		dst = tmp;
363 	}
364 	memcpy(skb_tail_pointer(dst), add->data, skb_headlen(add));
365 	cfpkt_destroy(addpkt);
366 	dst->tail += addlen;
367 	dst->len += addlen;
368 	return skb_to_pkt(dst);
369 }
370 EXPORT_SYMBOL(cfpkt_append);
371 
372 struct cfpkt *cfpkt_split(struct cfpkt *pkt, u16 pos)
373 {
374 	struct sk_buff *skb2;
375 	struct sk_buff *skb = pkt_to_skb(pkt);
376 	struct cfpkt *tmppkt;
377 	u8 *split = skb->data + pos;
378 	u16 len2nd = skb_tail_pointer(skb) - split;
379 
380 	if (unlikely(is_erronous(pkt)))
381 		return NULL;
382 
383 	if (skb->data + pos > skb_tail_pointer(skb)) {
384 		PKT_ERROR(pkt,
385 			  "cfpkt_split: trying to split beyond end of packet");
386 		return NULL;
387 	}
388 
389 	/* Create a new packet for the second part of the data */
390 	tmppkt = cfpkt_create_pfx(len2nd + PKT_PREFIX + PKT_POSTFIX,
391 				  PKT_PREFIX);
392 	if (tmppkt == NULL)
393 		return NULL;
394 	skb2 = pkt_to_skb(tmppkt);
395 
396 
397 	if (skb2 == NULL)
398 		return NULL;
399 
400 	/* Reduce the length of the original packet */
401 	skb_set_tail_pointer(skb, pos);
402 	skb->len = pos;
403 
404 	memcpy(skb2->data, split, len2nd);
405 	skb2->tail += len2nd;
406 	skb2->len += len2nd;
407 	return skb_to_pkt(skb2);
408 }
409 EXPORT_SYMBOL(cfpkt_split);
410 
411 char *cfpkt_log_pkt(struct cfpkt *pkt, char *buf, int buflen)
412 {
413 	struct sk_buff *skb = pkt_to_skb(pkt);
414 	char *p = buf;
415 	int i;
416 
417 	/*
418 	 * Sanity check buffer length, it needs to be at least as large as
419 	 * the header info: ~=50+ bytes
420 	 */
421 	if (buflen < 50)
422 		return NULL;
423 
424 	snprintf(buf, buflen, "%s: pkt:%p len:%ld(%ld+%ld) {%ld,%ld} data: [",
425 		is_erronous(pkt) ? "ERRONOUS-SKB" :
426 		 (skb->data_len != 0 ? "COMPLEX-SKB" : "SKB"),
427 		 skb,
428 		 (long) skb->len,
429 		 (long) (skb_tail_pointer(skb) - skb->data),
430 		 (long) skb->data_len,
431 		 (long) (skb->data - skb->head),
432 		 (long) (skb_tail_pointer(skb) - skb->head));
433 	p = buf + strlen(buf);
434 
435 	for (i = 0; i < skb_tail_pointer(skb) - skb->data && i < 300; i++) {
436 		if (p > buf + buflen - 10) {
437 			sprintf(p, "...");
438 			p = buf + strlen(buf);
439 			break;
440 		}
441 		sprintf(p, "%02x,", skb->data[i]);
442 		p = buf + strlen(buf);
443 	}
444 	sprintf(p, "]\n");
445 	return buf;
446 }
447 EXPORT_SYMBOL(cfpkt_log_pkt);
448 
449 int cfpkt_raw_append(struct cfpkt *pkt, void **buf, unsigned int buflen)
450 {
451 	struct sk_buff *skb = pkt_to_skb(pkt);
452 	struct sk_buff *lastskb;
453 
454 	caif_assert(buf != NULL);
455 	if (unlikely(is_erronous(pkt)))
456 		return -EPROTO;
457 	/* Make sure SKB is writable */
458 	if (unlikely(skb_cow_data(skb, 0, &lastskb) < 0)) {
459 		PKT_ERROR(pkt, "cfpkt_raw_append: skb_cow_data failed\n");
460 		return -EPROTO;
461 	}
462 
463 	if (unlikely(skb_linearize(skb) != 0)) {
464 		PKT_ERROR(pkt, "cfpkt_raw_append: linearize failed\n");
465 		return -EPROTO;
466 	}
467 
468 	if (unlikely(skb_tailroom(skb) < buflen)) {
469 		PKT_ERROR(pkt, "cfpkt_raw_append: buffer too short - failed\n");
470 		return -EPROTO;
471 	}
472 
473 	*buf = skb_put(skb, buflen);
474 	return 1;
475 }
476 EXPORT_SYMBOL(cfpkt_raw_append);
477 
478 int cfpkt_raw_extract(struct cfpkt *pkt, void **buf, unsigned int buflen)
479 {
480 	struct sk_buff *skb = pkt_to_skb(pkt);
481 
482 	caif_assert(buf != NULL);
483 	if (unlikely(is_erronous(pkt)))
484 		return -EPROTO;
485 
486 	if (unlikely(buflen > skb->len)) {
487 		PKT_ERROR(pkt, "cfpkt_raw_extract: buflen too large "
488 				"- failed\n");
489 		return -EPROTO;
490 	}
491 
492 	if (unlikely(buflen > skb_headlen(skb))) {
493 		if (unlikely(skb_linearize(skb) != 0)) {
494 			PKT_ERROR(pkt, "cfpkt_raw_extract: linearize failed\n");
495 			return -EPROTO;
496 		}
497 	}
498 
499 	*buf = skb->data;
500 	skb_pull(skb, buflen);
501 
502 	return 1;
503 }
504 EXPORT_SYMBOL(cfpkt_raw_extract);
505 
506 inline bool cfpkt_erroneous(struct cfpkt *pkt)
507 {
508 	return cfpkt_priv(pkt)->erronous;
509 }
510 EXPORT_SYMBOL(cfpkt_erroneous);
511 
512 struct cfpktq *cfpktq_create(void)
513 {
514 	struct cfpktq *q = kmalloc(sizeof(struct cfpktq), GFP_ATOMIC);
515 	if (!q)
516 		return NULL;
517 	skb_queue_head_init(&q->head);
518 	atomic_set(&q->count, 0);
519 	spin_lock_init(&q->lock);
520 	return q;
521 }
522 EXPORT_SYMBOL(cfpktq_create);
523 
524 void cfpkt_queue(struct cfpktq *pktq, struct cfpkt *pkt, unsigned short prio)
525 {
526 	atomic_inc(&pktq->count);
527 	spin_lock(&pktq->lock);
528 	skb_queue_tail(&pktq->head, pkt_to_skb(pkt));
529 	spin_unlock(&pktq->lock);
530 
531 }
532 EXPORT_SYMBOL(cfpkt_queue);
533 
534 struct cfpkt *cfpkt_qpeek(struct cfpktq *pktq)
535 {
536 	struct cfpkt *tmp;
537 	spin_lock(&pktq->lock);
538 	tmp = skb_to_pkt(skb_peek(&pktq->head));
539 	spin_unlock(&pktq->lock);
540 	return tmp;
541 }
542 EXPORT_SYMBOL(cfpkt_qpeek);
543 
544 struct cfpkt *cfpkt_dequeue(struct cfpktq *pktq)
545 {
546 	struct cfpkt *pkt;
547 	spin_lock(&pktq->lock);
548 	pkt = skb_to_pkt(skb_dequeue(&pktq->head));
549 	if (pkt) {
550 		atomic_dec(&pktq->count);
551 		caif_assert(atomic_read(&pktq->count) >= 0);
552 	}
553 	spin_unlock(&pktq->lock);
554 	return pkt;
555 }
556 EXPORT_SYMBOL(cfpkt_dequeue);
557 
558 int cfpkt_qcount(struct cfpktq *pktq)
559 {
560 	return atomic_read(&pktq->count);
561 }
562 EXPORT_SYMBOL(cfpkt_qcount);
563 
564 struct cfpkt *cfpkt_clone_release(struct cfpkt *pkt)
565 {
566 	struct cfpkt *clone;
567 	clone  = skb_to_pkt(skb_clone(pkt_to_skb(pkt), GFP_ATOMIC));
568 	/* Free original packet. */
569 	cfpkt_destroy(pkt);
570 	if (!clone)
571 		return NULL;
572 	return clone;
573 }
574 EXPORT_SYMBOL(cfpkt_clone_release);
575 
576 struct caif_payload_info *cfpkt_info(struct cfpkt *pkt)
577 {
578 	return (struct caif_payload_info *)&pkt_to_skb(pkt)->cb;
579 }
580 EXPORT_SYMBOL(cfpkt_info);
581