linux/net/sched/cls_tcindex.c
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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 <linux/slab.h>
  13#include <net/act_api.h>
  14#include <net/netlink.h>
  15#include <net/pkt_cls.h>
  16
  17/*
  18 * Passing parameters to the root seems to be done more awkwardly than really
  19 * necessary. At least, u32 doesn't seem to use such dirty hacks. To be
  20 * verified. FIXME.
  21 */
  22
  23#define PERFECT_HASH_THRESHOLD  64      /* use perfect hash if not bigger */
  24#define DEFAULT_HASH_SIZE       64      /* optimized for diffserv */
  25
  26
  27#define PRIV(tp)        ((struct tcindex_data *) (tp)->root)
  28
  29
  30struct tcindex_filter_result {
  31        struct tcf_exts         exts;
  32        struct tcf_result       res;
  33};
  34
  35struct tcindex_filter {
  36        u16 key;
  37        struct tcindex_filter_result result;
  38        struct tcindex_filter *next;
  39};
  40
  41
  42struct tcindex_data {
  43        struct tcindex_filter_result *perfect; /* perfect hash; NULL if none */
  44        struct tcindex_filter **h; /* imperfect hash; only used if !perfect;
  45                                      NULL if unused */
  46        u16 mask;               /* AND key with mask */
  47        int shift;              /* shift ANDed key to the right */
  48        int hash;               /* hash table size; 0 if undefined */
  49        int alloc_hash;         /* allocated size */
  50        int fall_through;       /* 0: only classify if explicit match */
  51};
  52
  53static const struct tcf_ext_map tcindex_ext_map = {
  54        .police = TCA_TCINDEX_POLICE,
  55        .action = TCA_TCINDEX_ACT
  56};
  57
  58static inline int
  59tcindex_filter_is_set(struct tcindex_filter_result *r)
  60{
  61        return tcf_exts_is_predicative(&r->exts) || r->res.classid;
  62}
  63
  64static struct tcindex_filter_result *
  65tcindex_lookup(struct tcindex_data *p, u16 key)
  66{
  67        struct tcindex_filter *f;
  68
  69        if (p->perfect)
  70                return tcindex_filter_is_set(p->perfect + key) ?
  71                        p->perfect + key : NULL;
  72        else if (p->h) {
  73                for (f = p->h[key % p->hash]; f; f = f->next)
  74                        if (f->key == key)
  75                                return &f->result;
  76        }
  77
  78        return NULL;
  79}
  80
  81
  82static int tcindex_classify(struct sk_buff *skb, const struct tcf_proto *tp,
  83                            struct tcf_result *res)
  84{
  85        struct tcindex_data *p = PRIV(tp);
  86        struct tcindex_filter_result *f;
  87        int key = (skb->tc_index & p->mask) >> p->shift;
  88
  89        pr_debug("tcindex_classify(skb %p,tp %p,res %p),p %p\n",
  90                 skb, tp, res, p);
  91
  92        f = tcindex_lookup(p, key);
  93        if (!f) {
  94                if (!p->fall_through)
  95                        return -1;
  96                res->classid = TC_H_MAKE(TC_H_MAJ(tp->q->handle), key);
  97                res->class = 0;
  98                pr_debug("alg 0x%x\n", res->classid);
  99                return 0;
 100        }
 101        *res = f->res;
 102        pr_debug("map 0x%x\n", res->classid);
 103
 104        return tcf_exts_exec(skb, &f->exts, res);
 105}
 106
 107
 108static unsigned long tcindex_get(struct tcf_proto *tp, u32 handle)
 109{
 110        struct tcindex_data *p = PRIV(tp);
 111        struct tcindex_filter_result *r;
 112
 113        pr_debug("tcindex_get(tp %p,handle 0x%08x)\n", tp, handle);
 114        if (p->perfect && handle >= p->alloc_hash)
 115                return 0;
 116        r = tcindex_lookup(p, handle);
 117        return r && tcindex_filter_is_set(r) ? (unsigned long) r : 0UL;
 118}
 119
 120
 121static void tcindex_put(struct tcf_proto *tp, unsigned long f)
 122{
 123        pr_debug("tcindex_put(tp %p,f 0x%lx)\n", tp, f);
 124}
 125
 126
 127static int tcindex_init(struct tcf_proto *tp)
 128{
 129        struct tcindex_data *p;
 130
 131        pr_debug("tcindex_init(tp %p)\n", tp);
 132        p = kzalloc(sizeof(struct tcindex_data), GFP_KERNEL);
 133        if (!p)
 134                return -ENOMEM;
 135
 136        p->mask = 0xffff;
 137        p->hash = DEFAULT_HASH_SIZE;
 138        p->fall_through = 1;
 139
 140        tp->root = p;
 141        return 0;
 142}
 143
 144
 145static int
 146__tcindex_delete(struct tcf_proto *tp, unsigned long arg, int lock)
 147{
 148        struct tcindex_data *p = PRIV(tp);
 149        struct tcindex_filter_result *r = (struct tcindex_filter_result *) arg;
 150        struct tcindex_filter *f = NULL;
 151
 152        pr_debug("tcindex_delete(tp %p,arg 0x%lx),p %p,f %p\n", tp, arg, p, f);
 153        if (p->perfect) {
 154                if (!r->res.class)
 155                        return -ENOENT;
 156        } else {
 157                int i;
 158                struct tcindex_filter **walk = NULL;
 159
 160                for (i = 0; i < p->hash; i++)
 161                        for (walk = p->h+i; *walk; walk = &(*walk)->next)
 162                                if (&(*walk)->result == r)
 163                                        goto found;
 164                return -ENOENT;
 165
 166found:
 167                f = *walk;
 168                if (lock)
 169                        tcf_tree_lock(tp);
 170                *walk = f->next;
 171                if (lock)
 172                        tcf_tree_unlock(tp);
 173        }
 174        tcf_unbind_filter(tp, &r->res);
 175        tcf_exts_destroy(tp, &r->exts);
 176        kfree(f);
 177        return 0;
 178}
 179
 180static int tcindex_delete(struct tcf_proto *tp, unsigned long arg)
 181{
 182        return __tcindex_delete(tp, arg, 1);
 183}
 184
 185static inline int
 186valid_perfect_hash(struct tcindex_data *p)
 187{
 188        return  p->hash > (p->mask >> p->shift);
 189}
 190
 191static const struct nla_policy tcindex_policy[TCA_TCINDEX_MAX + 1] = {
 192        [TCA_TCINDEX_HASH]              = { .type = NLA_U32 },
 193        [TCA_TCINDEX_MASK]              = { .type = NLA_U16 },
 194        [TCA_TCINDEX_SHIFT]             = { .type = NLA_U32 },
 195        [TCA_TCINDEX_FALL_THROUGH]      = { .type = NLA_U32 },
 196        [TCA_TCINDEX_CLASSID]           = { .type = NLA_U32 },
 197};
 198
 199static int
 200tcindex_set_parms(struct tcf_proto *tp, unsigned long base, u32 handle,
 201                  struct tcindex_data *p, struct tcindex_filter_result *r,
 202                  struct nlattr **tb, struct nlattr *est)
 203{
 204        int err, balloc = 0;
 205        struct tcindex_filter_result new_filter_result, *old_r = r;
 206        struct tcindex_filter_result cr;
 207        struct tcindex_data cp;
 208        struct tcindex_filter *f = NULL; /* make gcc behave */
 209        struct tcf_exts e;
 210
 211        err = tcf_exts_validate(tp, tb, est, &e, &tcindex_ext_map);
 212        if (err < 0)
 213                return err;
 214
 215        memcpy(&cp, p, sizeof(cp));
 216        memset(&new_filter_result, 0, sizeof(new_filter_result));
 217
 218        if (old_r)
 219                memcpy(&cr, r, sizeof(cr));
 220        else
 221                memset(&cr, 0, sizeof(cr));
 222
 223        if (tb[TCA_TCINDEX_HASH])
 224                cp.hash = nla_get_u32(tb[TCA_TCINDEX_HASH]);
 225
 226        if (tb[TCA_TCINDEX_MASK])
 227                cp.mask = nla_get_u16(tb[TCA_TCINDEX_MASK]);
 228
 229        if (tb[TCA_TCINDEX_SHIFT])
 230                cp.shift = nla_get_u32(tb[TCA_TCINDEX_SHIFT]);
 231
 232        err = -EBUSY;
 233        /* Hash already allocated, make sure that we still meet the
 234         * requirements for the allocated hash.
 235         */
 236        if (cp.perfect) {
 237                if (!valid_perfect_hash(&cp) ||
 238                    cp.hash > cp.alloc_hash)
 239                        goto errout;
 240        } else if (cp.h && cp.hash != cp.alloc_hash)
 241                goto errout;
 242
 243        err = -EINVAL;
 244        if (tb[TCA_TCINDEX_FALL_THROUGH])
 245                cp.fall_through = nla_get_u32(tb[TCA_TCINDEX_FALL_THROUGH]);
 246
 247        if (!cp.hash) {
 248                /* Hash not specified, use perfect hash if the upper limit
 249                 * of the hashing index is below the threshold.
 250                 */
 251                if ((cp.mask >> cp.shift) < PERFECT_HASH_THRESHOLD)
 252                        cp.hash = (cp.mask >> cp.shift) + 1;
 253                else
 254                        cp.hash = DEFAULT_HASH_SIZE;
 255        }
 256
 257        if (!cp.perfect && !cp.h)
 258                cp.alloc_hash = cp.hash;
 259
 260        /* Note: this could be as restrictive as if (handle & ~(mask >> shift))
 261         * but then, we'd fail handles that may become valid after some future
 262         * mask change. While this is extremely unlikely to ever matter,
 263         * the check below is safer (and also more backwards-compatible).
 264         */
 265        if (cp.perfect || valid_perfect_hash(&cp))
 266                if (handle >= cp.alloc_hash)
 267                        goto errout;
 268
 269
 270        err = -ENOMEM;
 271        if (!cp.perfect && !cp.h) {
 272                if (valid_perfect_hash(&cp)) {
 273                        cp.perfect = kcalloc(cp.hash, sizeof(*r), GFP_KERNEL);
 274                        if (!cp.perfect)
 275                                goto errout;
 276                        balloc = 1;
 277                } else {
 278                        cp.h = kcalloc(cp.hash, sizeof(f), GFP_KERNEL);
 279                        if (!cp.h)
 280                                goto errout;
 281                        balloc = 2;
 282                }
 283        }
 284
 285        if (cp.perfect)
 286                r = cp.perfect + handle;
 287        else
 288                r = tcindex_lookup(&cp, handle) ? : &new_filter_result;
 289
 290        if (r == &new_filter_result) {
 291                f = kzalloc(sizeof(*f), GFP_KERNEL);
 292                if (!f)
 293                        goto errout_alloc;
 294        }
 295
 296        if (tb[TCA_TCINDEX_CLASSID]) {
 297                cr.res.classid = nla_get_u32(tb[TCA_TCINDEX_CLASSID]);
 298                tcf_bind_filter(tp, &cr.res, base);
 299        }
 300
 301        tcf_exts_change(tp, &cr.exts, &e);
 302
 303        tcf_tree_lock(tp);
 304        if (old_r && old_r != r)
 305                memset(old_r, 0, sizeof(*old_r));
 306
 307        memcpy(p, &cp, sizeof(cp));
 308        memcpy(r, &cr, sizeof(cr));
 309
 310        if (r == &new_filter_result) {
 311                struct tcindex_filter **fp;
 312
 313                f->key = handle;
 314                f->result = new_filter_result;
 315                f->next = NULL;
 316                for (fp = p->h+(handle % p->hash); *fp; fp = &(*fp)->next)
 317                        /* nothing */;
 318                *fp = f;
 319        }
 320        tcf_tree_unlock(tp);
 321
 322        return 0;
 323
 324errout_alloc:
 325        if (balloc == 1)
 326                kfree(cp.perfect);
 327        else if (balloc == 2)
 328                kfree(cp.h);
 329errout:
 330        tcf_exts_destroy(tp, &e);
 331        return err;
 332}
 333
 334static int
 335tcindex_change(struct tcf_proto *tp, unsigned long base, u32 handle,
 336               struct nlattr **tca, unsigned long *arg)
 337{
 338        struct nlattr *opt = tca[TCA_OPTIONS];
 339        struct nlattr *tb[TCA_TCINDEX_MAX + 1];
 340        struct tcindex_data *p = PRIV(tp);
 341        struct tcindex_filter_result *r = (struct tcindex_filter_result *) *arg;
 342        int err;
 343
 344        pr_debug("tcindex_change(tp %p,handle 0x%08x,tca %p,arg %p),opt %p,"
 345            "p %p,r %p,*arg 0x%lx\n",
 346            tp, handle, tca, arg, opt, p, r, arg ? *arg : 0L);
 347
 348        if (!opt)
 349                return 0;
 350
 351        err = nla_parse_nested(tb, TCA_TCINDEX_MAX, opt, tcindex_policy);
 352        if (err < 0)
 353                return err;
 354
 355        return tcindex_set_parms(tp, base, handle, p, r, tb, tca[TCA_RATE]);
 356}
 357
 358
 359static void tcindex_walk(struct tcf_proto *tp, struct tcf_walker *walker)
 360{
 361        struct tcindex_data *p = PRIV(tp);
 362        struct tcindex_filter *f, *next;
 363        int i;
 364
 365        pr_debug("tcindex_walk(tp %p,walker %p),p %p\n", tp, walker, p);
 366        if (p->perfect) {
 367                for (i = 0; i < p->hash; i++) {
 368                        if (!p->perfect[i].res.class)
 369                                continue;
 370                        if (walker->count >= walker->skip) {
 371                                if (walker->fn(tp,
 372                                    (unsigned long) (p->perfect+i), walker)
 373                                     < 0) {
 374                                        walker->stop = 1;
 375                                        return;
 376                                }
 377                        }
 378                        walker->count++;
 379                }
 380        }
 381        if (!p->h)
 382                return;
 383        for (i = 0; i < p->hash; i++) {
 384                for (f = p->h[i]; f; f = next) {
 385                        next = f->next;
 386                        if (walker->count >= walker->skip) {
 387                                if (walker->fn(tp, (unsigned long) &f->result,
 388                                    walker) < 0) {
 389                                        walker->stop = 1;
 390                                        return;
 391                                }
 392                        }
 393                        walker->count++;
 394                }
 395        }
 396}
 397
 398
 399static int tcindex_destroy_element(struct tcf_proto *tp,
 400    unsigned long arg, struct tcf_walker *walker)
 401{
 402        return __tcindex_delete(tp, arg, 0);
 403}
 404
 405
 406static void tcindex_destroy(struct tcf_proto *tp)
 407{
 408        struct tcindex_data *p = PRIV(tp);
 409        struct tcf_walker walker;
 410
 411        pr_debug("tcindex_destroy(tp %p),p %p\n", tp, p);
 412        walker.count = 0;
 413        walker.skip = 0;
 414        walker.fn = &tcindex_destroy_element;
 415        tcindex_walk(tp, &walker);
 416        kfree(p->perfect);
 417        kfree(p->h);
 418        kfree(p);
 419        tp->root = NULL;
 420}
 421
 422
 423static int tcindex_dump(struct tcf_proto *tp, unsigned long fh,
 424    struct sk_buff *skb, struct tcmsg *t)
 425{
 426        struct tcindex_data *p = PRIV(tp);
 427        struct tcindex_filter_result *r = (struct tcindex_filter_result *) fh;
 428        unsigned char *b = skb_tail_pointer(skb);
 429        struct nlattr *nest;
 430
 431        pr_debug("tcindex_dump(tp %p,fh 0x%lx,skb %p,t %p),p %p,r %p,b %p\n",
 432                 tp, fh, skb, t, p, r, b);
 433        pr_debug("p->perfect %p p->h %p\n", p->perfect, p->h);
 434
 435        nest = nla_nest_start(skb, TCA_OPTIONS);
 436        if (nest == NULL)
 437                goto nla_put_failure;
 438
 439        if (!fh) {
 440                t->tcm_handle = ~0; /* whatever ... */
 441                if (nla_put_u32(skb, TCA_TCINDEX_HASH, p->hash) ||
 442                    nla_put_u16(skb, TCA_TCINDEX_MASK, p->mask) ||
 443                    nla_put_u32(skb, TCA_TCINDEX_SHIFT, p->shift) ||
 444                    nla_put_u32(skb, TCA_TCINDEX_FALL_THROUGH, p->fall_through))
 445                        goto nla_put_failure;
 446                nla_nest_end(skb, nest);
 447        } else {
 448                if (p->perfect) {
 449                        t->tcm_handle = r-p->perfect;
 450                } else {
 451                        struct tcindex_filter *f;
 452                        int i;
 453
 454                        t->tcm_handle = 0;
 455                        for (i = 0; !t->tcm_handle && i < p->hash; i++) {
 456                                for (f = p->h[i]; !t->tcm_handle && f;
 457                                     f = f->next) {
 458                                        if (&f->result == r)
 459                                                t->tcm_handle = f->key;
 460                                }
 461                        }
 462                }
 463                pr_debug("handle = %d\n", t->tcm_handle);
 464                if (r->res.class &&
 465                    nla_put_u32(skb, TCA_TCINDEX_CLASSID, r->res.classid))
 466                        goto nla_put_failure;
 467
 468                if (tcf_exts_dump(skb, &r->exts, &tcindex_ext_map) < 0)
 469                        goto nla_put_failure;
 470                nla_nest_end(skb, nest);
 471
 472                if (tcf_exts_dump_stats(skb, &r->exts, &tcindex_ext_map) < 0)
 473                        goto nla_put_failure;
 474        }
 475
 476        return skb->len;
 477
 478nla_put_failure:
 479        nlmsg_trim(skb, b);
 480        return -1;
 481}
 482
 483static struct tcf_proto_ops cls_tcindex_ops __read_mostly = {
 484        .kind           =       "tcindex",
 485        .classify       =       tcindex_classify,
 486        .init           =       tcindex_init,
 487        .destroy        =       tcindex_destroy,
 488        .get            =       tcindex_get,
 489        .put            =       tcindex_put,
 490        .change         =       tcindex_change,
 491        .delete         =       tcindex_delete,
 492        .walk           =       tcindex_walk,
 493        .dump           =       tcindex_dump,
 494        .owner          =       THIS_MODULE,
 495};
 496
 497static int __init init_tcindex(void)
 498{
 499        return register_tcf_proto_ops(&cls_tcindex_ops);
 500}
 501
 502static void __exit exit_tcindex(void)
 503{
 504        unregister_tcf_proto_ops(&cls_tcindex_ops);
 505}
 506
 507module_init(init_tcindex)
 508module_exit(exit_tcindex)
 509MODULE_LICENSE("GPL");
 510
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