net/caif/cfpkt_skbuff.c

   1 /*
   2  * Copyright (C) ST-Ericsson AB 2010
   3  * Author:      Sjur Brendeland/sjur.brandeland@stericsson.com
   4  * License terms: GNU General Public License (GPL) version 2
   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/hardirq.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
  45 static inline struct cfpkt_priv_data *cfpkt_priv(struct cfpkt *pkt)
  46 {
  47         return (struct cfpkt_priv_data *) pkt->skb.cb;
  48 }
  49
  50 static inline bool is_erronous(struct cfpkt *pkt)
  51 {
  52         return cfpkt_priv(pkt)->erronous;
  53 }
  54
  55 static inline struct sk_buff *pkt_to_skb(struct cfpkt *pkt)
  56 {
  57         return &pkt->skb;
  58 }
  59
  60 static inline struct cfpkt *skb_to_pkt(struct sk_buff *skb)
  61 {
  62         return (struct cfpkt *) skb;
  63 }
  64
  65
  66 struct cfpkt *cfpkt_fromnative(enum caif_direction dir, void *nativepkt)
  67 {
  68         struct cfpkt *pkt = skb_to_pkt(nativepkt);
  69         cfpkt_priv(pkt)->erronous = false;
  70         return pkt;
  71 }
  72 EXPORT_SYMBOL(cfpkt_fromnative);
  73
  74 void *cfpkt_tonative(struct cfpkt *pkt)
  75 {
  76         return (void *) pkt;
  77 }
  78 EXPORT_SYMBOL(cfpkt_tonative);
  79
  80 static struct cfpkt *cfpkt_create_pfx(u16 len, u16 pfx)
  81 {
  82         struct sk_buff *skb;
  83
  84         if (likely(in_interrupt()))
  85                 skb = alloc_skb(len + pfx, GFP_ATOMIC);
  86         else
  87                 skb = alloc_skb(len + pfx, GFP_KERNEL);
  88
  89         if (unlikely(skb == NULL))
  90                 return NULL;
  91
  92         skb_reserve(skb, pfx);
  93         return skb_to_pkt(skb);
  94 }
  95
  96 inline struct cfpkt *cfpkt_create(u16 len)
  97 {
  98         return cfpkt_create_pfx(len + PKT_POSTFIX, PKT_PREFIX);
  99 }
 100
 101 void cfpkt_destroy(struct cfpkt *pkt)
 102 {
 103         struct sk_buff *skb = pkt_to_skb(pkt);
 104         kfree_skb(skb);
 105 }
 106
 107
 108 inline bool cfpkt_more(struct cfpkt *pkt)
 109 {
 110         struct sk_buff *skb = pkt_to_skb(pkt);
 111         return skb->len > 0;
 112 }
 113
 114
 115 int cfpkt_peek_head(struct cfpkt *pkt, void *data, u16 len)
 116 {
 117         struct sk_buff *skb = pkt_to_skb(pkt);
 118         if (skb_headlen(skb) >= len) {
 119                 memcpy(data, skb->data, len);
 120                 return 0;
 121         }
 122         return !cfpkt_extr_head(pkt, data, len) &&
 123             !cfpkt_add_head(pkt, data, len);
 124 }
 125
 126 int cfpkt_extr_head(struct cfpkt *pkt, void *data, u16 len)
 127 {
 128         struct sk_buff *skb = pkt_to_skb(pkt);
 129         u8 *from;
 130         if (unlikely(is_erronous(pkt)))
 131                 return -EPROTO;
 132
 133         if (unlikely(len > skb->len)) {
 134                 PKT_ERROR(pkt, "read beyond end of packet\n");
 135                 return -EPROTO;
 136         }
 137
 138         if (unlikely(len > skb_headlen(skb))) {
 139                 if (unlikely(skb_linearize(skb) != 0)) {
 140                         PKT_ERROR(pkt, "linearize failed\n");
 141                         return -EPROTO;
 142                 }
 143         }
 144         from = skb_pull(skb, len);
 145         from -= len;
 146         memcpy(data, from, len);
 147         return 0;
 148 }
 149
 150 int cfpkt_extr_trail(struct cfpkt *pkt, void *dta, u16 len)
 151 {
 152         struct sk_buff *skb = pkt_to_skb(pkt);
 153         u8 *data = dta;
 154         u8 *from;
 155         if (unlikely(is_erronous(pkt)))
 156                 return -EPROTO;
 157
 158         if (unlikely(skb_linearize(skb) != 0)) {
 159                 PKT_ERROR(pkt, "linearize failed\n");
 160                 return -EPROTO;
 161         }
 162         if (unlikely(skb->data + len > skb_tail_pointer(skb))) {
 163                 PKT_ERROR(pkt, "read beyond end of packet\n");
 164                 return -EPROTO;
 165         }
 166         from = skb_tail_pointer(skb) - len;
 167         skb_trim(skb, skb->len - len);
 168         memcpy(data, from, len);
 169         return 0;
 170 }
 171
 172
 173 int cfpkt_pad_trail(struct cfpkt *pkt, u16 len)
 174 {
 175         return cfpkt_add_body(pkt, NULL, len);
 176 }
 177
 178
 179 int cfpkt_add_body(struct cfpkt *pkt, const void *data, u16 len)
 180 {
 181         struct sk_buff *skb = pkt_to_skb(pkt);
 182         struct sk_buff *lastskb;
 183         u8 *to;
 184         u16 addlen = 0;
 185
 186
 187         if (unlikely(is_erronous(pkt)))
 188                 return -EPROTO;
 189
 190         lastskb = skb;
 191
 192         /* Check whether we need to add space at the tail */
 193         if (unlikely(skb_tailroom(skb) < len)) {
 194                 if (likely(len < PKT_LEN_WHEN_EXTENDING))
 195                         addlen = PKT_LEN_WHEN_EXTENDING;
 196                 else
 197                         addlen = len;
 198         }
 199
 200         /* Check whether we need to change the SKB before writing to the tail */
 201         if (unlikely((addlen > 0) || skb_cloned(skb) || skb_shared(skb))) {
 202
 203                 /* Make sure data is writable */
 204                 if (unlikely(skb_cow_data(skb, addlen, &lastskb) < 0)) {
 205                         PKT_ERROR(pkt, "cow failed\n");
 206                         return -EPROTO;
 207                 }
 208                 /*
 209                  * Is the SKB non-linear after skb_cow_data()? If so, we are
 210                  * going to add data to the last SKB, so we need to adjust
 211                  * lengths of the top SKB.
 212                  */
 213                 if (lastskb != skb) {
 214                         pr_warn("Packet is non-linear\n");
 215                         skb->len += len;
 216                         skb->data_len += len;
 217                 }
 218         }
 219
 220         /* All set to put the last SKB and optionally write data there. */
 221         to = skb_put(lastskb, len);
 222         if (likely(data))
 223                 memcpy(to, data, len);
 224         return 0;
 225 }
 226
 227 inline int cfpkt_addbdy(struct cfpkt *pkt, u8 data)
 228 {
 229         return cfpkt_add_body(pkt, &data, 1);
 230 }
 231
 232 int cfpkt_add_head(struct cfpkt *pkt, const void *data2, u16 len)
 233 {
 234         struct sk_buff *skb = pkt_to_skb(pkt);
 235         struct sk_buff *lastskb;
 236         u8 *to;
 237         const u8 *data = data2;
 238         int ret;
 239         if (unlikely(is_erronous(pkt)))
 240                 return -EPROTO;
 241         if (unlikely(skb_headroom(skb) < len)) {
 242                 PKT_ERROR(pkt, "no headroom\n");
 243                 return -EPROTO;
 244         }
 245
 246         /* Make sure data is writable */
 247         ret = skb_cow_data(skb, 0, &lastskb);
 248         if (unlikely(ret < 0)) {
 249                 PKT_ERROR(pkt, "cow failed\n");
 250                 return ret;
 251         }
 252
 253         to = skb_push(skb, len);
 254         memcpy(to, data, len);
 255         return 0;
 256 }
 257
 258
 259 inline int cfpkt_add_trail(struct cfpkt *pkt, const void *data, u16 len)
 260 {
 261         return cfpkt_add_body(pkt, data, len);
 262 }
 263
 264
 265 inline u16 cfpkt_getlen(struct cfpkt *pkt)
 266 {
 267         struct sk_buff *skb = pkt_to_skb(pkt);
 268         return skb->len;
 269 }
 270
 271
 272 inline u16 cfpkt_iterate(struct cfpkt *pkt,
 273                             u16 (*iter_func)(u16, void *, u16),
 274                             u16 data)
 275 {
 276         /*
 277          * Don't care about the performance hit of linearizing,
 278          * Checksum should not be used on high-speed interfaces anyway.
 279          */
 280         if (unlikely(is_erronous(pkt)))
 281                 return -EPROTO;
 282         if (unlikely(skb_linearize(&pkt->skb) != 0)) {
 283                 PKT_ERROR(pkt, "linearize failed\n");
 284                 return -EPROTO;
 285         }
 286         return iter_func(data, pkt->skb.data, cfpkt_getlen(pkt));
 287 }
 288
 289
 290 int cfpkt_setlen(struct cfpkt *pkt, u16 len)
 291 {
 292         struct sk_buff *skb = pkt_to_skb(pkt);
 293
 294
 295         if (unlikely(is_erronous(pkt)))
 296                 return -EPROTO;
 297
 298         if (likely(len <= skb->len)) {
 299                 if (unlikely(skb->data_len))
 300                         ___pskb_trim(skb, len);
 301                 else
 302                         skb_trim(skb, len);
 303
 304                         return cfpkt_getlen(pkt);
 305         }
 306
 307         /* Need to expand SKB */
 308         if (unlikely(!cfpkt_pad_trail(pkt, len - skb->len)))
 309                 PKT_ERROR(pkt, "skb_pad_trail failed\n");
 310
 311         return cfpkt_getlen(pkt);
 312 }
 313
 314 struct cfpkt *cfpkt_append(struct cfpkt *dstpkt,
 315                              struct cfpkt *addpkt,
 316                              u16 expectlen)
 317 {
 318         struct sk_buff *dst = pkt_to_skb(dstpkt);
 319         struct sk_buff *add = pkt_to_skb(addpkt);
 320         u16 addlen = skb_headlen(add);
 321         u16 neededtailspace;
 322         struct sk_buff *tmp;
 323         u16 dstlen;
 324         u16 createlen;
 325         if (unlikely(is_erronous(dstpkt) || is_erronous(addpkt))) {
 326                 return dstpkt;
 327         }
 328         if (expectlen > addlen)
 329                 neededtailspace = expectlen;
 330         else
 331                 neededtailspace = addlen;
 332
 333         if (dst->tail + neededtailspace > dst->end) {
 334                 /* Create a dumplicate of 'dst' with more tail space */
 335                 struct cfpkt *tmppkt;
 336                 dstlen = skb_headlen(dst);
 337                 createlen = dstlen + neededtailspace;
 338                 tmppkt = cfpkt_create(createlen + PKT_PREFIX + PKT_POSTFIX);
 339                 if (tmppkt == NULL)
 340                         return NULL;
 341                 tmp = pkt_to_skb(tmppkt);
 342                 skb_set_tail_pointer(tmp, dstlen);
 343                 tmp->len = dstlen;
 344                 memcpy(tmp->data, dst->data, dstlen);
 345                 cfpkt_destroy(dstpkt);
 346                 dst = tmp;
 347         }
 348         memcpy(skb_tail_pointer(dst), add->data, skb_headlen(add));
 349         cfpkt_destroy(addpkt);
 350         dst->tail += addlen;
 351         dst->len += addlen;
 352         return skb_to_pkt(dst);
 353 }
 354
 355 struct cfpkt *cfpkt_split(struct cfpkt *pkt, u16 pos)
 356 {
 357         struct sk_buff *skb2;
 358         struct sk_buff *skb = pkt_to_skb(pkt);
 359         struct cfpkt *tmppkt;
 360         u8 *split = skb->data + pos;
 361         u16 len2nd = skb_tail_pointer(skb) - split;
 362
 363         if (unlikely(is_erronous(pkt)))
 364                 return NULL;
 365
 366         if (skb->data + pos > skb_tail_pointer(skb)) {
 367                 PKT_ERROR(pkt, "trying to split beyond end of packet\n");
 368                 return NULL;
 369         }
 370
 371         /* Create a new packet for the second part of the data */
 372         tmppkt = cfpkt_create_pfx(len2nd + PKT_PREFIX + PKT_POSTFIX,
 373                                   PKT_PREFIX);
 374         if (tmppkt == NULL)
 375                 return NULL;
 376         skb2 = pkt_to_skb(tmppkt);
 377
 378
 379         if (skb2 == NULL)
 380                 return NULL;
 381
 382         /* Reduce the length of the original packet */
 383         skb_set_tail_pointer(skb, pos);
 384         skb->len = pos;
 385
 386         memcpy(skb2->data, split, len2nd);
 387         skb2->tail += len2nd;
 388         skb2->len += len2nd;
 389         return skb_to_pkt(skb2);
 390 }
 391
 392 bool cfpkt_erroneous(struct cfpkt *pkt)
 393 {
 394         return cfpkt_priv(pkt)->erronous;
 395 }
 396
 397 struct caif_payload_info *cfpkt_info(struct cfpkt *pkt)
 398 {
 399         return (struct caif_payload_info *)&pkt_to_skb(pkt)->cb;
 400 }