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(skb: 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(size: len + pfx, GFP_ATOMIC);
84 if (unlikely(skb == NULL))
85 return NULL;
86
87 skb_reserve(skb, len: pfx);
88 return skb_to_pkt(skb);
89}
90
91inline struct cfpkt *cfpkt_create(u16 len)
92{
93 return cfpkt_create_pfx(len: 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, len: 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, tail: 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: &data, len: 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, tailbits: 0, trailer: &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(pkt: dstpkt);
299 struct sk_buff *add = pkt_to_skb(pkt: addpkt);
300 u16 addlen = skb_headlen(skb: 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(skb: dst);
317 createlen = dstlen + neededtailspace;
318 tmppkt = cfpkt_create(len: createlen + PKT_PREFIX + PKT_POSTFIX);
319 if (tmppkt == NULL)
320 return NULL;
321 tmp = pkt_to_skb(pkt: tmppkt);
322 skb_put_data(skb: tmp, data: dst->data, len: dstlen);
323 cfpkt_destroy(pkt: dstpkt);
324 dst = tmp;
325 }
326 skb_put_data(skb: dst, data: add->data, len: skb_headlen(skb: add));
327 cfpkt_destroy(pkt: addpkt);
328 return skb_to_pkt(skb: 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(len: len2nd + PKT_PREFIX + PKT_POSTFIX,
349 PKT_PREFIX);
350 if (tmppkt == NULL)
351 return NULL;
352 skb2 = pkt_to_skb(pkt: tmppkt);
353
354
355 if (skb2 == NULL)
356 return NULL;
357
358 skb_put_data(skb: skb2, data: split, len: len2nd);
359
360 /* Reduce the length of the original packet */
361 skb_trim(skb, len: pos);
362
363 skb2->priority = skb->priority;
364 return skb_to_pkt(skb: 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

source code of linux/net/caif/cfpkt_skbuff.c