net/caif/cfpkt_skbuff.c

   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
 302         neededtailspace = max(expectlen, addlen);
 303
 304         if (dst->tail + neededtailspace > dst->end) {
 305                 /* Create a dumplicate of 'dst' with more tail space */
 306                 struct cfpkt *tmppkt;
 307                 dstlen = skb_headlen(dst);
 308                 createlen = dstlen + neededtailspace;
 309                 tmppkt = cfpkt_create(createlen + PKT_PREFIX + PKT_POSTFIX);
 310                 if (tmppkt == NULL)
 311                         return NULL;
 312                 tmp = pkt_to_skb(tmppkt);
 313                 skb_put_data(tmp, dst->data, dstlen);
 314                 cfpkt_destroy(dstpkt);
 315                 dst = tmp;
 316         }
 317         skb_put_data(dst, add->data, skb_headlen(add));
 318         cfpkt_destroy(addpkt);
 319         return skb_to_pkt(dst);
 320 }
 321
 322 struct cfpkt *cfpkt_split(struct cfpkt *pkt, u16 pos)
 323 {
 324         struct sk_buff *skb2;
 325         struct sk_buff *skb = pkt_to_skb(pkt);
 326         struct cfpkt *tmppkt;
 327         u8 *split = skb->data + pos;
 328         u16 len2nd = skb_tail_pointer(skb) - split;
 329
 330         if (unlikely(is_erronous(pkt)))
 331                 return NULL;
 332
 333         if (skb->data + pos > skb_tail_pointer(skb)) {
 334                 PKT_ERROR(pkt, "trying to split beyond end of packet\n");
 335                 return NULL;
 336         }
 337
 338         /* Create a new packet for the second part of the data */
 339         tmppkt = cfpkt_create_pfx(len2nd + PKT_PREFIX + PKT_POSTFIX,
 340                                   PKT_PREFIX);
 341         if (tmppkt == NULL)
 342                 return NULL;
 343         skb2 = pkt_to_skb(tmppkt);
 344
 345
 346         if (skb2 == NULL)
 347                 return NULL;
 348
 349         skb_put_data(skb2, split, len2nd);
 350
 351         /* Reduce the length of the original packet */
 352         skb_trim(skb, pos);
 353
 354         skb2->priority = skb->priority;
 355         return skb_to_pkt(skb2);
 356 }
 357
 358 bool cfpkt_erroneous(struct cfpkt *pkt)
 359 {
 360         return cfpkt_priv(pkt)->erronous;
 361 }
 362
 363 struct caif_payload_info *cfpkt_info(struct cfpkt *pkt)
 364 {
 365         return (struct caif_payload_info *)&pkt_to_skb(pkt)->cb;
 366 }
 367 EXPORT_SYMBOL(cfpkt_info);
 368
 369 void cfpkt_set_prio(struct cfpkt *pkt, int prio)
 370 {
 371         pkt_to_skb(pkt)->priority = prio;
 372 }
 373 EXPORT_SYMBOL(cfpkt_set_prio);