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)		   \
18 do {					   \
19 	cfpkt_priv(pkt)->erronous = true;  \
20 	skb_reset_tail_pointer(&pkt->skb); \
21 	pr_warn(errmsg);		   \
22 } while (0)
23 
24 struct 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  */
35 struct cfpkt {
36 	struct sk_buff skb;
37 };
38 
39 /* Private data inside SKB */
40 struct cfpkt_priv_data {
41 	struct dev_info dev_info;
42 	bool erronous;
43 };
44 
cfpkt_priv(struct cfpkt * pkt)45 static inline struct cfpkt_priv_data *cfpkt_priv(struct cfpkt *pkt)
46 {
47 	return (struct cfpkt_priv_data *) pkt->skb.cb;
48 }
49 
is_erronous(struct cfpkt * pkt)50 static inline bool is_erronous(struct cfpkt *pkt)
51 {
52 	return cfpkt_priv(pkt)->erronous;
53 }
54 
pkt_to_skb(struct cfpkt * pkt)55 static inline struct sk_buff *pkt_to_skb(struct cfpkt *pkt)
56 {
57 	return &pkt->skb;
58 }
59 
skb_to_pkt(struct sk_buff * skb)60 static inline struct cfpkt *skb_to_pkt(struct sk_buff *skb)
61 {
62 	return (struct cfpkt *) skb;
63 }
64 
cfpkt_fromnative(enum caif_direction dir,void * nativepkt)65 struct 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 }
71 EXPORT_SYMBOL(cfpkt_fromnative);
72 
cfpkt_tonative(struct cfpkt * pkt)73 void *cfpkt_tonative(struct cfpkt *pkt)
74 {
75 	return (void *) pkt;
76 }
77 EXPORT_SYMBOL(cfpkt_tonative);
78 
cfpkt_create_pfx(u16 len,u16 pfx)79 static 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 
cfpkt_create(u16 len)91 inline struct cfpkt *cfpkt_create(u16 len)
92 {
93 	return cfpkt_create_pfx(len + PKT_POSTFIX, PKT_PREFIX);
94 }
95 
cfpkt_destroy(struct cfpkt * pkt)96 void cfpkt_destroy(struct cfpkt *pkt)
97 {
98 	struct sk_buff *skb = pkt_to_skb(pkt);
99 	kfree_skb(skb);
100 }
101 
cfpkt_more(struct cfpkt * pkt)102 inline bool cfpkt_more(struct cfpkt *pkt)
103 {
104 	struct sk_buff *skb = pkt_to_skb(pkt);
105 	return skb->len > 0;
106 }
107 
cfpkt_peek_head(struct cfpkt * pkt,void * data,u16 len)108 int 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 
cfpkt_extr_head(struct cfpkt * pkt,void * data,u16 len)119 int 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 }
143 EXPORT_SYMBOL(cfpkt_extr_head);
144 
cfpkt_extr_trail(struct cfpkt * pkt,void * dta,u16 len)145 int 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 
cfpkt_pad_trail(struct cfpkt * pkt,u16 len)167 int cfpkt_pad_trail(struct cfpkt *pkt, u16 len)
168 {
169 	return cfpkt_add_body(pkt, NULL, len);
170 }
171 
cfpkt_add_body(struct cfpkt * pkt,const void * data,u16 len)172 int 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 
cfpkt_addbdy(struct cfpkt * pkt,u8 data)210 inline int cfpkt_addbdy(struct cfpkt *pkt, u8 data)
211 {
212 	return cfpkt_add_body(pkt, &data, 1);
213 }
214 
cfpkt_add_head(struct cfpkt * pkt,const void * data2,u16 len)215 int 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 }
240 EXPORT_SYMBOL(cfpkt_add_head);
241 
cfpkt_add_trail(struct cfpkt * pkt,const void * data,u16 len)242 inline int cfpkt_add_trail(struct cfpkt *pkt, const void *data, u16 len)
243 {
244 	return cfpkt_add_body(pkt, data, len);
245 }
246 
cfpkt_getlen(struct cfpkt * pkt)247 inline u16 cfpkt_getlen(struct cfpkt *pkt)
248 {
249 	struct sk_buff *skb = pkt_to_skb(pkt);
250 	return skb->len;
251 }
252 
cfpkt_iterate(struct cfpkt * pkt,u16 (* iter_func)(u16,void *,u16),u16 data)253 int 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 
cfpkt_setlen(struct cfpkt * pkt,u16 len)270 int 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 
cfpkt_append(struct cfpkt * dstpkt,struct cfpkt * addpkt,u16 expectlen)294 struct 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 
cfpkt_split(struct cfpkt * pkt,u16 pos)331 struct 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 
cfpkt_erroneous(struct cfpkt * pkt)367 bool cfpkt_erroneous(struct cfpkt *pkt)
368 {
369 	return cfpkt_priv(pkt)->erronous;
370 }
371 
cfpkt_info(struct cfpkt * pkt)372 struct caif_payload_info *cfpkt_info(struct cfpkt *pkt)
373 {
374 	return (struct caif_payload_info *)&pkt_to_skb(pkt)->cb;
375 }
376 EXPORT_SYMBOL(cfpkt_info);
377 
cfpkt_set_prio(struct cfpkt * pkt,int prio)378 void cfpkt_set_prio(struct cfpkt *pkt, int prio)
379 {
380 	pkt_to_skb(pkt)->priority = prio;
381 }
382 EXPORT_SYMBOL(cfpkt_set_prio);
383