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