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