1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) ST-Ericsson AB 2010
4 * Author:	Sjur Brendeland
5 */
6
7#define pr_fmt(fmt) KBUILD_MODNAME ":%s(): " fmt, __func__
8
9#include <linux/string.h>
10#include <linux/skbuff.h>
11#include <linux/export.h>
12#include <net/caif/cfpkt.h>
13
14#define PKT_PREFIX  48
15#define PKT_POSTFIX 2
16#define PKT_LEN_WHEN_EXTENDING 128
17#define PKT_ERROR(pkt, errmsg)		   \
18do {					   \
19	cfpkt_priv(pkt)->erronous = true;  \
20	skb_reset_tail_pointer(&pkt->skb); \
21	pr_warn(errmsg);		   \
22} while (0)
23
24struct cfpktq {
25	struct sk_buff_head head;
26	atomic_t count;
27	/* Lock protects count updates */
28	spinlock_t lock;
29};
30
31/*
32 * net/caif/ is generic and does not
33 * understand SKB, so we do this typecast
34 */
35struct cfpkt {
36	struct sk_buff skb;
37};
38
39/* Private data inside SKB */
40struct cfpkt_priv_data {
41	struct dev_info dev_info;
42	bool erronous;
43};
44
45static inline struct cfpkt_priv_data *cfpkt_priv(struct cfpkt *pkt)
46{
47	return (struct cfpkt_priv_data *) pkt->skb.cb;
48}
49
50static inline bool is_erronous(struct cfpkt *pkt)
51{
52	return cfpkt_priv(pkt)->erronous;
53}
54
55static inline struct sk_buff *pkt_to_skb(struct cfpkt *pkt)
56{
57	return &pkt->skb;
58}
59
60static inline struct cfpkt *skb_to_pkt(struct sk_buff *skb)
61{
62	return (struct cfpkt *) skb;
63}
64
65struct cfpkt *cfpkt_fromnative(enum caif_direction dir, void *nativepkt)
66{
67	struct cfpkt *pkt = skb_to_pkt(nativepkt);
68	cfpkt_priv(pkt)->erronous = false;
69	return pkt;
70}
71EXPORT_SYMBOL(cfpkt_fromnative);
72
73void *cfpkt_tonative(struct cfpkt *pkt)
74{
75	return (void *) pkt;
76}
77EXPORT_SYMBOL(cfpkt_tonative);
78
79static struct cfpkt *cfpkt_create_pfx(u16 len, u16 pfx)
80{
81	struct sk_buff *skb;
82
83	skb = alloc_skb(len + pfx, GFP_ATOMIC);
84	if (unlikely(skb == NULL))
85		return NULL;
86
87	skb_reserve(skb, pfx);
88	return skb_to_pkt(skb);
89}
90
91inline struct cfpkt *cfpkt_create(u16 len)
92{
93	return cfpkt_create_pfx(len + PKT_POSTFIX, PKT_PREFIX);
94}
95
96void cfpkt_destroy(struct cfpkt *pkt)
97{
98	struct sk_buff *skb = pkt_to_skb(pkt);
99	kfree_skb(skb);
100}
101
102inline bool cfpkt_more(struct cfpkt *pkt)
103{
104	struct sk_buff *skb = pkt_to_skb(pkt);
105	return skb->len > 0;
106}
107
108int cfpkt_peek_head(struct cfpkt *pkt, void *data, u16 len)
109{
110	struct sk_buff *skb = pkt_to_skb(pkt);
111	if (skb_headlen(skb) >= len) {
112		memcpy(data, skb->data, len);
113		return 0;
114	}
115	return !cfpkt_extr_head(pkt, data, len) &&
116	    !cfpkt_add_head(pkt, data, len);
117}
118
119int cfpkt_extr_head(struct cfpkt *pkt, void *data, u16 len)
120{
121	struct sk_buff *skb = pkt_to_skb(pkt);
122	u8 *from;
123	if (unlikely(is_erronous(pkt)))
124		return -EPROTO;
125
126	if (unlikely(len > skb->len)) {
127		PKT_ERROR(pkt, "read beyond end of packet\n");
128		return -EPROTO;
129	}
130
131	if (unlikely(len > skb_headlen(skb))) {
132		if (unlikely(skb_linearize(skb) != 0)) {
133			PKT_ERROR(pkt, "linearize failed\n");
134			return -EPROTO;
135		}
136	}
137	from = skb_pull(skb, len);
138	from -= len;
139	if (data)
140		memcpy(data, from, len);
141	return 0;
142}
143EXPORT_SYMBOL(cfpkt_extr_head);
144
145int cfpkt_extr_trail(struct cfpkt *pkt, void *dta, u16 len)
146{
147	struct sk_buff *skb = pkt_to_skb(pkt);
148	u8 *data = dta;
149	u8 *from;
150	if (unlikely(is_erronous(pkt)))
151		return -EPROTO;
152
153	if (unlikely(skb_linearize(skb) != 0)) {
154		PKT_ERROR(pkt, "linearize failed\n");
155		return -EPROTO;
156	}
157	if (unlikely(skb->data + len > skb_tail_pointer(skb))) {
158		PKT_ERROR(pkt, "read beyond end of packet\n");
159		return -EPROTO;
160	}
161	from = skb_tail_pointer(skb) - len;
162	skb_trim(skb, skb->len - len);
163	memcpy(data, from, len);
164	return 0;
165}
166
167int cfpkt_pad_trail(struct cfpkt *pkt, u16 len)
168{
169	return cfpkt_add_body(pkt, NULL, len);
170}
171
172int cfpkt_add_body(struct cfpkt *pkt, const void *data, u16 len)
173{
174	struct sk_buff *skb = pkt_to_skb(pkt);
175	struct sk_buff *lastskb;
176	u8 *to;
177	u16 addlen = 0;
178
179
180	if (unlikely(is_erronous(pkt)))
181		return -EPROTO;
182
183	lastskb = skb;
184
185	/* Check whether we need to add space at the tail */
186	if (unlikely(skb_tailroom(skb) < len)) {
187		if (likely(len < PKT_LEN_WHEN_EXTENDING))
188			addlen = PKT_LEN_WHEN_EXTENDING;
189		else
190			addlen = len;
191	}
192
193	/* Check whether we need to change the SKB before writing to the tail */
194	if (unlikely((addlen > 0) || skb_cloned(skb) || skb_shared(skb))) {
195
196		/* Make sure data is writable */
197		if (unlikely(skb_cow_data(skb, addlen, &lastskb) < 0)) {
198			PKT_ERROR(pkt, "cow failed\n");
199			return -EPROTO;
200		}
201	}
202
203	/* All set to put the last SKB and optionally write data there. */
204	to = pskb_put(skb, lastskb, len);
205	if (likely(data))
206		memcpy(to, data, len);
207	return 0;
208}
209
210inline int cfpkt_addbdy(struct cfpkt *pkt, u8 data)
211{
212	return cfpkt_add_body(pkt, &data, 1);
213}
214
215int cfpkt_add_head(struct cfpkt *pkt, const void *data2, u16 len)
216{
217	struct sk_buff *skb = pkt_to_skb(pkt);
218	struct sk_buff *lastskb;
219	u8 *to;
220	const u8 *data = data2;
221	int ret;
222	if (unlikely(is_erronous(pkt)))
223		return -EPROTO;
224	if (unlikely(skb_headroom(skb) < len)) {
225		PKT_ERROR(pkt, "no headroom\n");
226		return -EPROTO;
227	}
228
229	/* Make sure data is writable */
230	ret = skb_cow_data(skb, 0, &lastskb);
231	if (unlikely(ret < 0)) {
232		PKT_ERROR(pkt, "cow failed\n");
233		return ret;
234	}
235
236	to = skb_push(skb, len);
237	memcpy(to, data, len);
238	return 0;
239}
240EXPORT_SYMBOL(cfpkt_add_head);
241
242inline int cfpkt_add_trail(struct cfpkt *pkt, const void *data, u16 len)
243{
244	return cfpkt_add_body(pkt, data, len);
245}
246
247inline u16 cfpkt_getlen(struct cfpkt *pkt)
248{
249	struct sk_buff *skb = pkt_to_skb(pkt);
250	return skb->len;
251}
252
253int cfpkt_iterate(struct cfpkt *pkt,
254		  u16 (*iter_func)(u16, void *, u16),
255		  u16 data)
256{
257	/*
258	 * Don't care about the performance hit of linearizing,
259	 * Checksum should not be used on high-speed interfaces anyway.
260	 */
261	if (unlikely(is_erronous(pkt)))
262		return -EPROTO;
263	if (unlikely(skb_linearize(&pkt->skb) != 0)) {
264		PKT_ERROR(pkt, "linearize failed\n");
265		return -EPROTO;
266	}
267	return iter_func(data, pkt->skb.data, cfpkt_getlen(pkt));
268}
269
270int cfpkt_setlen(struct cfpkt *pkt, u16 len)
271{
272	struct sk_buff *skb = pkt_to_skb(pkt);
273
274
275	if (unlikely(is_erronous(pkt)))
276		return -EPROTO;
277
278	if (likely(len <= skb->len)) {
279		if (unlikely(skb->data_len))
280			___pskb_trim(skb, len);
281		else
282			skb_trim(skb, len);
283
284		return cfpkt_getlen(pkt);
285	}
286
287	/* Need to expand SKB */
288	if (unlikely(!cfpkt_pad_trail(pkt, len - skb->len)))
289		PKT_ERROR(pkt, "skb_pad_trail failed\n");
290
291	return cfpkt_getlen(pkt);
292}
293
294struct cfpkt *cfpkt_append(struct cfpkt *dstpkt,
295			   struct cfpkt *addpkt,
296			   u16 expectlen)
297{
298	struct sk_buff *dst = pkt_to_skb(dstpkt);
299	struct sk_buff *add = pkt_to_skb(addpkt);
300	u16 addlen = skb_headlen(add);
301	u16 neededtailspace;
302	struct sk_buff *tmp;
303	u16 dstlen;
304	u16 createlen;
305	if (unlikely(is_erronous(dstpkt) || is_erronous(addpkt))) {
306		return dstpkt;
307	}
308	if (expectlen > addlen)
309		neededtailspace = expectlen;
310	else
311		neededtailspace = addlen;
312
313	if (dst->tail + neededtailspace > dst->end) {
314		/* Create a dumplicate of 'dst' with more tail space */
315		struct cfpkt *tmppkt;
316		dstlen = skb_headlen(dst);
317		createlen = dstlen + neededtailspace;
318		tmppkt = cfpkt_create(createlen + PKT_PREFIX + PKT_POSTFIX);
319		if (tmppkt == NULL)
320			return NULL;
321		tmp = pkt_to_skb(tmppkt);
322		skb_put_data(tmp, dst->data, dstlen);
323		cfpkt_destroy(dstpkt);
324		dst = tmp;
325	}
326	skb_put_data(dst, add->data, skb_headlen(add));
327	cfpkt_destroy(addpkt);
328	return skb_to_pkt(dst);
329}
330
331struct cfpkt *cfpkt_split(struct cfpkt *pkt, u16 pos)
332{
333	struct sk_buff *skb2;
334	struct sk_buff *skb = pkt_to_skb(pkt);
335	struct cfpkt *tmppkt;
336	u8 *split = skb->data + pos;
337	u16 len2nd = skb_tail_pointer(skb) - split;
338
339	if (unlikely(is_erronous(pkt)))
340		return NULL;
341
342	if (skb->data + pos > skb_tail_pointer(skb)) {
343		PKT_ERROR(pkt, "trying to split beyond end of packet\n");
344		return NULL;
345	}
346
347	/* Create a new packet for the second part of the data */
348	tmppkt = cfpkt_create_pfx(len2nd + PKT_PREFIX + PKT_POSTFIX,
349				  PKT_PREFIX);
350	if (tmppkt == NULL)
351		return NULL;
352	skb2 = pkt_to_skb(tmppkt);
353
354
355	if (skb2 == NULL)
356		return NULL;
357
358	skb_put_data(skb2, split, len2nd);
359
360	/* Reduce the length of the original packet */
361	skb_trim(skb, pos);
362
363	skb2->priority = skb->priority;
364	return skb_to_pkt(skb2);
365}
366
367bool cfpkt_erroneous(struct cfpkt *pkt)
368{
369	return cfpkt_priv(pkt)->erronous;
370}
371
372struct caif_payload_info *cfpkt_info(struct cfpkt *pkt)
373{
374	return (struct caif_payload_info *)&pkt_to_skb(pkt)->cb;
375}
376EXPORT_SYMBOL(cfpkt_info);
377
378void cfpkt_set_prio(struct cfpkt *pkt, int prio)
379{
380	pkt_to_skb(pkt)->priority = prio;
381}
382EXPORT_SYMBOL(cfpkt_set_prio);
383