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   1 /*
   2  * net/sched/cls_tcindex.c      Packet classifier for skb->tc_index
   3  *
   4  * Written 1998,1999 by Werner Almesberger, EPFL ICA
   5  */
   6
   7 #include <linux/module.h>
   8 #include <linux/types.h>
   9 #include <linux/kernel.h>
  10 #include <linux/skbuff.h>
  11 #include <linux/errno.h>
  12 #include <net/act_api.h>
  13 #include <net/netlink.h>
  14 #include <net/pkt_cls.h>
  15
  16
  17 /*
  18  * Not quite sure if we need all the xchgs Alexey uses when accessing things.
  19  * Can always add them later ... :)
  20  */
  21
  22 /*
  23  * Passing parameters to the root seems to be done more awkwardly than really
  24  * necessary. At least, u32 doesn't seem to use such dirty hacks. To be
  25  * verified. FIXME.
  26  */
  27
  28 #define PERFECT_HASH_THRESHOLD  64      /* use perfect hash if not bigger */
  29 #define DEFAULT_HASH_SIZE       64      /* optimized for diffserv */
  30
  31
  32 #define PRIV(tp)        ((struct tcindex_data *) (tp)->root)
  33
  34
  35 struct tcindex_filter_result {
  36         struct tcf_exts         exts;
  37         struct tcf_result       res;
  38 };
  39
  40 struct tcindex_filter {
  41         u16 key;
  42         struct tcindex_filter_result result;
  43         struct tcindex_filter *next;
  44 };
  45
  46
  47 struct tcindex_data {
  48         struct tcindex_filter_result *perfect; /* perfect hash; NULL if none */
  49         struct tcindex_filter **h; /* imperfect hash; only used if !perfect;
  50                                       NULL if unused */
  51         u16 mask;               /* AND key with mask */
  52         int shift;              /* shift ANDed key to the right */
  53         int hash;               /* hash table size; 0 if undefined */
  54         int alloc_hash;         /* allocated size */
  55         int fall_through;       /* 0: only classify if explicit match */
  56 };
  57
  58 static const struct tcf_ext_map tcindex_ext_map = {
  59         .police = TCA_TCINDEX_POLICE,
  60         .action = TCA_TCINDEX_ACT
  61 };
  62
  63 static inline int
  64 tcindex_filter_is_set(struct tcindex_filter_result *r)
  65 {
  66         return tcf_exts_is_predicative(&r->exts) || r->res.classid;
  67 }
  68
  69 static struct tcindex_filter_result *
  70 tcindex_lookup(struct tcindex_data *p, u16 key)
  71 {
  72         struct tcindex_filter *f;
  73
  74         if (p->perfect)
  75                 return tcindex_filter_is_set(p->perfect + key) ?
  76                         p->perfect + key : NULL;
  77         else if (p->h) {
  78                 for (f = p->h[key % p->hash]; f; f = f->next)
  79                         if (f->key == key)
  80                                 return &f->result;
  81         }
  82
  83         return NULL;
  84 }
  85
  86
  87 static int tcindex_classify(struct sk_buff *skb, struct tcf_proto *tp,
  88                             struct tcf_result *res)
  89 {
  90         struct tcindex_data *p = PRIV(tp);
  91         struct tcindex_filter_result *f;
  92         int key = (skb->tc_index & p->mask) >> p->shift;
  93
  94         pr_debug("tcindex_classify(skb %p,tp %p,res %p),p %p\n",
  95                  skb, tp, res, p);
  96
  97         f = tcindex_lookup(p, key);
  98         if (!f) {
  99                 if (!p->fall_through)
 100                         return -1;
 101                 res->classid = TC_H_MAKE(TC_H_MAJ(tp->q->handle), key);
 102                 res->class = 0;
 103                 pr_debug("alg 0x%x\n", res->classid);
 104                 return 0;
 105         }
 106         *res = f->res;
 107         pr_debug("map 0x%x\n", res->classid);
 108
 109         return tcf_exts_exec(skb, &f->exts, res);
 110 }
 111
 112
 113 static unsigned long tcindex_get(struct tcf_proto *tp, u32 handle)
 114 {
 115         struct tcindex_data *p = PRIV(tp);
 116         struct tcindex_filter_result *r;
 117
 118         pr_debug("tcindex_get(tp %p,handle 0x%08x)\n", tp, handle);
 119         if (p->perfect && handle >= p->alloc_hash)
 120                 return 0;
 121         r = tcindex_lookup(p, handle);
 122         return r && tcindex_filter_is_set(r) ? (unsigned long) r : 0UL;
 123 }
 124
 125
 126 static void tcindex_put(struct tcf_proto *tp, unsigned long f)
 127 {
 128         pr_debug("tcindex_put(tp %p,f 0x%lx)\n", tp, f);
 129 }
 130
 131
 132 static int tcindex_init(struct tcf_proto *tp)
 133 {
 134         struct tcindex_data *p;
 135
 136         pr_debug("tcindex_init(tp %p)\n", tp);
 137         p = kzalloc(sizeof(struct tcindex_data), GFP_KERNEL);
 138         if (!p)
 139                 return -ENOMEM;
 140
 141         p->mask = 0xffff;
 142         p->hash = DEFAULT_HASH_SIZE;
 143         p->fall_through = 1;
 144
 145         tp->root = p;
 146         return 0;
 147 }
 148
 149
 150 static int
 151 __tcindex_delete(struct tcf_proto *tp, unsigned long arg, int lock)
 152 {
 153         struct tcindex_data *p = PRIV(tp);
 154         struct tcindex_filter_result *r = (struct tcindex_filter_result *) arg;
 155         struct tcindex_filter *f = NULL;
 156
 157         pr_debug("tcindex_delete(tp %p,arg 0x%lx),p %p,f %p\n", tp, arg, p, f);
 158         if (p->perfect) {
 159                 if (!r->res.class)
 160                         return -ENOENT;
 161         } else {
 162                 int i;
 163                 struct tcindex_filter **walk = NULL;
 164
 165                 for (i = 0; i < p->hash; i++)
 166                         for (walk = p->h+i; *walk; walk = &(*walk)->next)
 167                                 if (&(*walk)->result == r)
 168                                         goto found;
 169                 return -ENOENT;
 170
 171 found:
 172                 f = *walk;
 173                 if (lock)
 174                         tcf_tree_lock(tp);
 175                 *walk = f->next;
 176                 if (lock)
 177                         tcf_tree_unlock(tp);
 178         }
 179         tcf_unbind_filter(tp, &r->res);
 180         tcf_exts_destroy(tp, &r->exts);
 181         kfree(f);
 182         return 0;
 183 }
 184
 185 static int tcindex_delete(struct tcf_proto *tp, unsigned long arg)
 186 {
 187         return __tcindex_delete(tp, arg, 1);
 188 }
 189
 190 static inline int
 191 valid_perfect_hash(struct tcindex_data *p)
 192 {
 193         return  p->hash > (p->mask >> p->shift);
 194 }
 195
 196 static const struct nla_policy tcindex_policy[TCA_TCINDEX_MAX + 1] = {
 197         [TCA_TCINDEX_HASH]              = { .type = NLA_U32 },
 198         [TCA_TCINDEX_MASK]              = { .type = NLA_U16 },
 199         [TCA_TCINDEX_SHIFT]             = { .type = NLA_U32 },
 200         [TCA_TCINDEX_FALL_THROUGH]      = { .type = NLA_U32 },
 201         [TCA_TCINDEX_CLASSID]           = { .type = NLA_U32 },
 202 };
 203
 204 static int
 205 tcindex_set_parms(struct tcf_proto *tp, unsigned long base, u32 handle,
 206                   struct tcindex_data *p, struct tcindex_filter_result *r,
 207                   struct nlattr **tb, struct nlattr *est)
 208 {
 209         int err, balloc = 0;
 210         struct tcindex_filter_result new_filter_result, *old_r = r;
 211         struct tcindex_filter_result cr;
 212         struct tcindex_data cp;
 213         struct tcindex_filter *f = NULL; /* make gcc behave */
 214         struct tcf_exts e;
 215
 216         err = tcf_exts_validate(tp, tb, est, &e, &tcindex_ext_map);
 217         if (err < 0)
 218                 return err;
 219
 220         memcpy(&cp, p, sizeof(cp));
 221         memset(&new_filter_result, 0, sizeof(new_filter_result));
 222
 223         if (old_r)
 224                 memcpy(&cr, r, sizeof(cr));
 225         else
 226                 memset(&cr, 0, sizeof(cr));
 227
 228         if (tb[TCA_TCINDEX_HASH])
 229                 cp.hash = nla_get_u32(tb[TCA_TCINDEX_HASH]);
 230
 231         if (tb[TCA_TCINDEX_MASK])
 232                 cp.mask = nla_get_u16(tb[TCA_TCINDEX_MASK]);
 233
 234         if (tb[TCA_TCINDEX_SHIFT])
 235                 cp.shift = nla_get_u32(tb[TCA_TCINDEX_SHIFT]);
 236
 237         err = -EBUSY;
 238         /* Hash already allocated, make sure that we still meet the
 239          * requirements for the allocated hash.
 240          */
 241         if (cp.perfect) {
 242                 if (!valid_perfect_hash(&cp) ||
 243                     cp.hash > cp.alloc_hash)
 244                         goto errout;
 245         } else if (cp.h && cp.hash != cp.alloc_hash)
 246                 goto errout;
 247
 248         err = -EINVAL;
 249         if (tb[TCA_TCINDEX_FALL_THROUGH])
 250                 cp.fall_through = nla_get_u32(tb[TCA_TCINDEX_FALL_THROUGH]);
 251
 252         if (!cp.hash) {
 253                 /* Hash not specified, use perfect hash if the upper limit
 254                  * of the hashing index is below the threshold.
 255                  */
 256                 if ((cp.mask >> cp.shift) < PERFECT_HASH_THRESHOLD)
 257                         cp.hash = (cp.mask >> cp.shift)+1;
 258                 else
 259                         cp.hash = DEFAULT_HASH_SIZE;
 260         }
 261
 262         if (!cp.perfect && !cp.h)
 263                 cp.alloc_hash = cp.hash;
 264
 265         /* Note: this could be as restrictive as if (handle & ~(mask >> shift))
 266          * but then, we'd fail handles that may become valid after some future
 267          * mask change. While this is extremely unlikely to ever matter,
 268          * the check below is safer (and also more backwards-compatible).
 269          */
 270         if (cp.perfect || valid_perfect_hash(&cp))
 271                 if (handle >= cp.alloc_hash)
 272                         goto errout;
 273
 274
 275         err = -ENOMEM;
 276         if (!cp.perfect && !cp.h) {
 277                 if (valid_perfect_hash(&cp)) {
 278                         cp.perfect = kcalloc(cp.hash, sizeof(*r), GFP_KERNEL);
 279                         if (!cp.perfect)
 280                                 goto errout;
 281                         balloc = 1;
 282                 } else {
 283                         cp.h = kcalloc(cp.hash, sizeof(f), GFP_KERNEL);
 284                         if (!cp.h)
 285                                 goto errout;
 286                         balloc = 2;
 287                 }
 288         }
 289
 290         if (cp.perfect)
 291                 r = cp.perfect + handle;
 292         else
 293                 r = tcindex_lookup(&cp, handle) ? : &new_filter_result;
 294
 295         if (r == &new_filter_result) {
 296                 f = kzalloc(sizeof(*f), GFP_KERNEL);
 297                 if (!f)
 298                         goto errout_alloc;
 299         }
 300
 301         if (tb[TCA_TCINDEX_CLASSID]) {
 302                 cr.res.classid = nla_get_u32(tb[TCA_TCINDEX_CLASSID]);
 303                 tcf_bind_filter(tp, &cr.res, base);
 304         }
 305
 306         tcf_exts_change(tp, &cr.exts, &e);
 307
 308         tcf_tree_lock(tp);
 309         if (old_r && old_r != r)
 310                 memset(old_r, 0, sizeof(*old_r));
 311
 312         memcpy(p, &cp, sizeof(cp));
 313         memcpy(r, &cr, sizeof(cr));
 314
 315         if (r == &new_filter_result) {
 316                 struct tcindex_filter **fp;
 317
 318                 f->key = handle;
 319                 f->result = new_filter_result;
 320                 f->next = NULL;
 321                 for (fp = p->h+(handle % p->hash); *fp; fp = &(*fp)->next)
 322                         /* nothing */;
 323                 *fp = f;
 324         }
 325         tcf_tree_unlock(tp);
 326
 327         return 0;
 328
 329 errout_alloc:
 330         if (balloc == 1)
 331                 kfree(cp.perfect);
 332         else if (balloc == 2)
 333                 kfree(cp.h);
 334 errout:
 335         tcf_exts_destroy(tp, &e);
 336         return err;
 337 }
 338
 339 static int
 340 tcindex_change(struct tcf_proto *tp, unsigned long base, u32 handle,
 341                struct nlattr **tca, unsigned long *arg)
 342 {
 343         struct nlattr *opt = tca[TCA_OPTIONS];
 344         struct nlattr *tb[TCA_TCINDEX_MAX + 1];
 345         struct tcindex_data *p = PRIV(tp);
 346         struct tcindex_filter_result *r = (struct tcindex_filter_result *) *arg;
 347         int err;
 348
 349         pr_debug("tcindex_change(tp %p,handle 0x%08x,tca %p,arg %p),opt %p,"
 350             "p %p,r %p,*arg 0x%lx\n",
 351             tp, handle, tca, arg, opt, p, r, arg ? *arg : 0L);
 352
 353         if (!opt)
 354                 return 0;
 355
 356         err = nla_parse_nested(tb, TCA_TCINDEX_MAX, opt, tcindex_policy);
 357         if (err < 0)
 358                 return err;
 359
 360         return tcindex_set_parms(tp, base, handle, p, r, tb, tca[TCA_RATE]);
 361 }
 362
 363
 364 static void tcindex_walk(struct tcf_proto *tp, struct tcf_walker *walker)
 365 {
 366         struct tcindex_data *p = PRIV(tp);
 367         struct tcindex_filter *f, *next;
 368         int i;
 369
 370         pr_debug("tcindex_walk(tp %p,walker %p),p %p\n", tp, walker, p);
 371         if (p->perfect) {
 372                 for (i = 0; i < p->hash; i++) {
 373                         if (!p->perfect[i].res.class)
 374                                 continue;
 375                         if (walker->count >= walker->skip) {
 376                                 if (walker->fn(tp,
 377                                     (unsigned long) (p->perfect+i), walker)
 378                                      < 0) {
 379                                         walker->stop = 1;
 380                                         return;
 381                                 }
 382                         }
 383                         walker->count++;
 384                 }
 385         }
 386         if (!p->h)
 387                 return;
 388         for (i = 0; i < p->hash; i++) {
 389                 for (f = p->h[i]; f; f = next) {
 390                         next = f->next;
 391                         if (walker->count >= walker->skip) {
 392                                 if (walker->fn(tp, (unsigned long) &f->result,
 393                                     walker) < 0) {
 394                                         walker->stop = 1;
 395                                         return;
 396                                 }
 397                         }
 398                         walker->count++;
 399                 }
 400         }
 401 }
 402
 403
 404 static int tcindex_destroy_element(struct tcf_proto *tp,
 405     unsigned long arg, struct tcf_walker *walker)
 406 {
 407         return __tcindex_delete(tp, arg, 0);
 408 }
 409
 410
 411 static void tcindex_destroy(struct tcf_proto *tp)
 412 {
 413         struct tcindex_data *p = PRIV(tp);
 414         struct tcf_walker walker;
 415
 416         pr_debug("tcindex_destroy(tp %p),p %p\n", tp, p);
 417         walker.count = 0;
 418         walker.skip = 0;
 419         walker.fn = &tcindex_destroy_element;
 420         tcindex_walk(tp, &walker);
 421         kfree(p->perfect);
 422         kfree(p->h);
 423         kfree(p);
 424         tp->root = NULL;
 425 }
 426
 427
 428 static int tcindex_dump(struct tcf_proto *tp, unsigned long fh,
 429     struct sk_buff *skb, struct tcmsg *t)
 430 {
 431         struct tcindex_data *p = PRIV(tp);
 432         struct tcindex_filter_result *r = (struct tcindex_filter_result *) fh;
 433         unsigned char *b = skb_tail_pointer(skb);
 434         struct nlattr *nest;
 435
 436         pr_debug("tcindex_dump(tp %p,fh 0x%lx,skb %p,t %p),p %p,r %p,b %p\n",
 437                  tp, fh, skb, t, p, r, b);
 438         pr_debug("p->perfect %p p->h %p\n", p->perfect, p->h);
 439
 440         nest = nla_nest_start(skb, TCA_OPTIONS);
 441         if (nest == NULL)
 442                 goto nla_put_failure;
 443
 444         if (!fh) {
 445                 t->tcm_handle = ~0; /* whatever ... */
 446                 NLA_PUT_U32(skb, TCA_TCINDEX_HASH, p->hash);
 447                 NLA_PUT_U16(skb, TCA_TCINDEX_MASK, p->mask);
 448                 NLA_PUT_U32(skb, TCA_TCINDEX_SHIFT, p->shift);
 449                 NLA_PUT_U32(skb, TCA_TCINDEX_FALL_THROUGH, p->fall_through);
 450                 nla_nest_end(skb, nest);
 451         } else {
 452                 if (p->perfect) {
 453                         t->tcm_handle = r-p->perfect;
 454                 } else {
 455                         struct tcindex_filter *f;
 456                         int i;
 457
 458                         t->tcm_handle = 0;
 459                         for (i = 0; !t->tcm_handle && i < p->hash; i++) {
 460                                 for (f = p->h[i]; !t->tcm_handle && f;
 461                                      f = f->next) {
 462                                         if (&f->result == r)
 463                                                 t->tcm_handle = f->key;
 464                                 }
 465                         }
 466                 }
 467                 pr_debug("handle = %d\n", t->tcm_handle);
 468                 if (r->res.class)
 469                         NLA_PUT_U32(skb, TCA_TCINDEX_CLASSID, r->res.classid);
 470
 471                 if (tcf_exts_dump(skb, &r->exts, &tcindex_ext_map) < 0)
 472                         goto nla_put_failure;
 473                 nla_nest_end(skb, nest);
 474
 475                 if (tcf_exts_dump_stats(skb, &r->exts, &tcindex_ext_map) < 0)
 476                         goto nla_put_failure;
 477         }
 478
 479         return skb->len;
 480
 481 nla_put_failure:
 482         nlmsg_trim(skb, b);
 483         return -1;
 484 }
 485
 486 static struct tcf_proto_ops cls_tcindex_ops __read_mostly = {
 487         .kind           =       "tcindex",
 488         .classify       =       tcindex_classify,
 489         .init           =       tcindex_init,
 490         .destroy        =       tcindex_destroy,
 491         .get            =       tcindex_get,
 492         .put            =       tcindex_put,
 493         .change         =       tcindex_change,
 494         .delete         =       tcindex_delete,
 495         .walk           =       tcindex_walk,
 496         .dump           =       tcindex_dump,
 497         .owner          =       THIS_MODULE,
 498 };
 499
 500 static int __init init_tcindex(void)
 501 {
 502         return register_tcf_proto_ops(&cls_tcindex_ops);
 503 }
 504
 505 static void __exit exit_tcindex(void)
 506 {
 507         unregister_tcf_proto_ops(&cls_tcindex_ops);
 508 }
 509
 510 module_init(init_tcindex)
 511 module_exit(exit_tcindex)
 512 MODULE_LICENSE("GPL");