security/selinux/ss/avtab.c

   1 /*
   2  * Implementation of the access vector table type.
   3  *
   4  * Author : Stephen Smalley, <sds@epoch.ncsc.mil>
   5  */
   6
   7 /* Updated: Frank Mayer <mayerf@tresys.com> and Karl MacMillan <kmacmillan@tresys.com>
   8  *
   9  *      Added conditional policy language extensions
  10  *
  11  * Copyright (C) 2003 Tresys Technology, LLC
  12  *      This program is free software; you can redistribute it and/or modify
  13  *      it under the terms of the GNU General Public License as published by
  14  *      the Free Software Foundation, version 2.
  15  *
  16  * Updated: Yuichi Nakamura <ynakam@hitachisoft.jp>
  17  *      Tuned number of hash slots for avtab to reduce memory usage
  18  */
  19
  20 #include <linux/kernel.h>
  21 #include <linux/slab.h>
  22 #include <linux/errno.h>
  23 #include "avtab.h"
  24 #include "policydb.h"
  25
  26 static struct kmem_cache *avtab_node_cachep;
  27
  28 /* Based on MurmurHash3, written by Austin Appleby and placed in the
  29  * public domain.
  30  */
  31 static inline int avtab_hash(struct avtab_key *keyp, u32 mask)
  32 {
  33         static const u32 c1 = 0xcc9e2d51;
  34         static const u32 c2 = 0x1b873593;
  35         static const u32 r1 = 15;
  36         static const u32 r2 = 13;
  37         static const u32 m  = 5;
  38         static const u32 n  = 0xe6546b64;
  39
  40         u32 hash = 0;
  41
  42 #define mix(input) { \
  43         u32 v = input; \
  44         v *= c1; \
  45         v = (v << r1) | (v >> (32 - r1)); \
  46         v *= c2; \
  47         hash ^= v; \
  48         hash = (hash << r2) | (hash >> (32 - r2)); \
  49         hash = hash * m + n; \
  50 }
  51
  52         mix(keyp->target_class);
  53         mix(keyp->target_type);
  54         mix(keyp->source_type);
  55
  56 #undef mix
  57
  58         hash ^= hash >> 16;
  59         hash *= 0x85ebca6b;
  60         hash ^= hash >> 13;
  61         hash *= 0xc2b2ae35;
  62         hash ^= hash >> 16;
  63
  64         return hash & mask;
  65 }
  66
  67 static struct avtab_node*
  68 avtab_insert_node(struct avtab *h, int hvalue,
  69                   struct avtab_node *prev, struct avtab_node *cur,
  70                   struct avtab_key *key, struct avtab_datum *datum)
  71 {
  72         struct avtab_node *newnode;
  73         newnode = kmem_cache_zalloc(avtab_node_cachep, GFP_KERNEL);
  74         if (newnode == NULL)
  75                 return NULL;
  76         newnode->key = *key;
  77         newnode->datum = *datum;
  78         if (prev) {
  79                 newnode->next = prev->next;
  80                 prev->next = newnode;
  81         } else {
  82                 newnode->next = flex_array_get_ptr(h->htable, hvalue);
  83                 if (flex_array_put_ptr(h->htable, hvalue, newnode,
  84                                        GFP_KERNEL|__GFP_ZERO)) {
  85                         kmem_cache_free(avtab_node_cachep, newnode);
  86                         return NULL;
  87                 }
  88         }
  89
  90         h->nel++;
  91         return newnode;
  92 }
  93
  94 static int avtab_insert(struct avtab *h, struct avtab_key *key, struct avtab_datum *datum)
  95 {
  96         int hvalue;
  97         struct avtab_node *prev, *cur, *newnode;
  98         u16 specified = key->specified & ~(AVTAB_ENABLED|AVTAB_ENABLED_OLD);
  99
 100         if (!h || !h->htable)
 101                 return -EINVAL;
 102
 103         hvalue = avtab_hash(key, h->mask);
 104         for (prev = NULL, cur = flex_array_get_ptr(h->htable, hvalue);
 105              cur;
 106              prev = cur, cur = cur->next) {
 107                 if (key->source_type == cur->key.source_type &&
 108                     key->target_type == cur->key.target_type &&
 109                     key->target_class == cur->key.target_class &&
 110                     (specified & cur->key.specified))
 111                         return -EEXIST;
 112                 if (key->source_type < cur->key.source_type)
 113                         break;
 114                 if (key->source_type == cur->key.source_type &&
 115                     key->target_type < cur->key.target_type)
 116                         break;
 117                 if (key->source_type == cur->key.source_type &&
 118                     key->target_type == cur->key.target_type &&
 119                     key->target_class < cur->key.target_class)
 120                         break;
 121         }
 122
 123         newnode = avtab_insert_node(h, hvalue, prev, cur, key, datum);
 124         if (!newnode)
 125                 return -ENOMEM;
 126
 127         return 0;
 128 }
 129
 130 /* Unlike avtab_insert(), this function allow multiple insertions of the same
 131  * key/specified mask into the table, as needed by the conditional avtab.
 132  * It also returns a pointer to the node inserted.
 133  */
 134 struct avtab_node *
 135 avtab_insert_nonunique(struct avtab *h, struct avtab_key *key, struct avtab_datum *datum)
 136 {
 137         int hvalue;
 138         struct avtab_node *prev, *cur;
 139         u16 specified = key->specified & ~(AVTAB_ENABLED|AVTAB_ENABLED_OLD);
 140
 141         if (!h || !h->htable)
 142                 return NULL;
 143         hvalue = avtab_hash(key, h->mask);
 144         for (prev = NULL, cur = flex_array_get_ptr(h->htable, hvalue);
 145              cur;
 146              prev = cur, cur = cur->next) {
 147                 if (key->source_type == cur->key.source_type &&
 148                     key->target_type == cur->key.target_type &&
 149                     key->target_class == cur->key.target_class &&
 150                     (specified & cur->key.specified))
 151                         break;
 152                 if (key->source_type < cur->key.source_type)
 153                         break;
 154                 if (key->source_type == cur->key.source_type &&
 155                     key->target_type < cur->key.target_type)
 156                         break;
 157                 if (key->source_type == cur->key.source_type &&
 158                     key->target_type == cur->key.target_type &&
 159                     key->target_class < cur->key.target_class)
 160                         break;
 161         }
 162         return avtab_insert_node(h, hvalue, prev, cur, key, datum);
 163 }
 164
 165 struct avtab_datum *avtab_search(struct avtab *h, struct avtab_key *key)
 166 {
 167         int hvalue;
 168         struct avtab_node *cur;
 169         u16 specified = key->specified & ~(AVTAB_ENABLED|AVTAB_ENABLED_OLD);
 170
 171         if (!h || !h->htable)
 172                 return NULL;
 173
 174         hvalue = avtab_hash(key, h->mask);
 175         for (cur = flex_array_get_ptr(h->htable, hvalue); cur;
 176              cur = cur->next) {
 177                 if (key->source_type == cur->key.source_type &&
 178                     key->target_type == cur->key.target_type &&
 179                     key->target_class == cur->key.target_class &&
 180                     (specified & cur->key.specified))
 181                         return &cur->datum;
 182
 183                 if (key->source_type < cur->key.source_type)
 184                         break;
 185                 if (key->source_type == cur->key.source_type &&
 186                     key->target_type < cur->key.target_type)
 187                         break;
 188                 if (key->source_type == cur->key.source_type &&
 189                     key->target_type == cur->key.target_type &&
 190                     key->target_class < cur->key.target_class)
 191                         break;
 192         }
 193
 194         return NULL;
 195 }
 196
 197 /* This search function returns a node pointer, and can be used in
 198  * conjunction with avtab_search_next_node()
 199  */
 200 struct avtab_node*
 201 avtab_search_node(struct avtab *h, struct avtab_key *key)
 202 {
 203         int hvalue;
 204         struct avtab_node *cur;
 205         u16 specified = key->specified & ~(AVTAB_ENABLED|AVTAB_ENABLED_OLD);
 206
 207         if (!h || !h->htable)
 208                 return NULL;
 209
 210         hvalue = avtab_hash(key, h->mask);
 211         for (cur = flex_array_get_ptr(h->htable, hvalue); cur;
 212              cur = cur->next) {
 213                 if (key->source_type == cur->key.source_type &&
 214                     key->target_type == cur->key.target_type &&
 215                     key->target_class == cur->key.target_class &&
 216                     (specified & cur->key.specified))
 217                         return cur;
 218
 219                 if (key->source_type < cur->key.source_type)
 220                         break;
 221                 if (key->source_type == cur->key.source_type &&
 222                     key->target_type < cur->key.target_type)
 223                         break;
 224                 if (key->source_type == cur->key.source_type &&
 225                     key->target_type == cur->key.target_type &&
 226                     key->target_class < cur->key.target_class)
 227                         break;
 228         }
 229         return NULL;
 230 }
 231
 232 struct avtab_node*
 233 avtab_search_node_next(struct avtab_node *node, int specified)
 234 {
 235         struct avtab_node *cur;
 236
 237         if (!node)
 238                 return NULL;
 239
 240         specified &= ~(AVTAB_ENABLED|AVTAB_ENABLED_OLD);
 241         for (cur = node->next; cur; cur = cur->next) {
 242                 if (node->key.source_type == cur->key.source_type &&
 243                     node->key.target_type == cur->key.target_type &&
 244                     node->key.target_class == cur->key.target_class &&
 245                     (specified & cur->key.specified))
 246                         return cur;
 247
 248                 if (node->key.source_type < cur->key.source_type)
 249                         break;
 250                 if (node->key.source_type == cur->key.source_type &&
 251                     node->key.target_type < cur->key.target_type)
 252                         break;
 253                 if (node->key.source_type == cur->key.source_type &&
 254                     node->key.target_type == cur->key.target_type &&
 255                     node->key.target_class < cur->key.target_class)
 256                         break;
 257         }
 258         return NULL;
 259 }
 260
 261 void avtab_destroy(struct avtab *h)
 262 {
 263         int i;
 264         struct avtab_node *cur, *temp;
 265
 266         if (!h || !h->htable)
 267                 return;
 268
 269         for (i = 0; i < h->nslot; i++) {
 270                 cur = flex_array_get_ptr(h->htable, i);
 271                 while (cur) {
 272                         temp = cur;
 273                         cur = cur->next;
 274                         kmem_cache_free(avtab_node_cachep, temp);
 275                 }
 276         }
 277         flex_array_free(h->htable);
 278         h->htable = NULL;
 279         h->nslot = 0;
 280         h->mask = 0;
 281 }
 282
 283 int avtab_init(struct avtab *h)
 284 {
 285         h->htable = NULL;
 286         h->nel = 0;
 287         return 0;
 288 }
 289
 290 int avtab_alloc(struct avtab *h, u32 nrules)
 291 {
 292         u32 mask = 0;
 293         u32 shift = 0;
 294         u32 work = nrules;
 295         u32 nslot = 0;
 296
 297         if (nrules == 0)
 298                 goto avtab_alloc_out;
 299
 300         while (work) {
 301                 work  = work >> 1;
 302                 shift++;
 303         }
 304         if (shift > 2)
 305                 shift = shift - 2;
 306         nslot = 1 << shift;
 307         if (nslot > MAX_AVTAB_HASH_BUCKETS)
 308                 nslot = MAX_AVTAB_HASH_BUCKETS;
 309         mask = nslot - 1;
 310
 311         h->htable = flex_array_alloc(sizeof(struct avtab_node *), nslot,
 312                                      GFP_KERNEL | __GFP_ZERO);
 313         if (!h->htable)
 314                 return -ENOMEM;
 315
 316  avtab_alloc_out:
 317         h->nel = 0;
 318         h->nslot = nslot;
 319         h->mask = mask;
 320         printk(KERN_DEBUG "SELinux: %d avtab hash slots, %d rules.\n",
 321                h->nslot, nrules);
 322         return 0;
 323 }
 324
 325 void avtab_hash_eval(struct avtab *h, char *tag)
 326 {
 327         int i, chain_len, slots_used, max_chain_len;
 328         unsigned long long chain2_len_sum;
 329         struct avtab_node *cur;
 330
 331         slots_used = 0;
 332         max_chain_len = 0;
 333         chain2_len_sum = 0;
 334         for (i = 0; i < h->nslot; i++) {
 335                 cur = flex_array_get_ptr(h->htable, i);
 336                 if (cur) {
 337                         slots_used++;
 338                         chain_len = 0;
 339                         while (cur) {
 340                                 chain_len++;
 341                                 cur = cur->next;
 342                         }
 343
 344                         if (chain_len > max_chain_len)
 345                                 max_chain_len = chain_len;
 346                         chain2_len_sum += chain_len * chain_len;
 347                 }
 348         }
 349
 350         printk(KERN_DEBUG "SELinux: %s:  %d entries and %d/%d buckets used, "
 351                "longest chain length %d sum of chain length^2 %llu\n",
 352                tag, h->nel, slots_used, h->nslot, max_chain_len,
 353                chain2_len_sum);
 354 }
 355
 356 static uint16_t spec_order[] = {
 357         AVTAB_ALLOWED,
 358         AVTAB_AUDITDENY,
 359         AVTAB_AUDITALLOW,
 360         AVTAB_TRANSITION,
 361         AVTAB_CHANGE,
 362         AVTAB_MEMBER
 363 };
 364
 365 int avtab_read_item(struct avtab *a, void *fp, struct policydb *pol,
 366                     int (*insertf)(struct avtab *a, struct avtab_key *k,
 367                                    struct avtab_datum *d, void *p),
 368                     void *p)
 369 {
 370         __le16 buf16[4];
 371         u16 enabled;
 372         __le32 buf32[7];
 373         u32 items, items2, val, vers = pol->policyvers;
 374         struct avtab_key key;
 375         struct avtab_datum datum;
 376         int i, rc;
 377         unsigned set;
 378
 379         memset(&key, 0, sizeof(struct avtab_key));
 380         memset(&datum, 0, sizeof(struct avtab_datum));
 381
 382         if (vers < POLICYDB_VERSION_AVTAB) {
 383                 rc = next_entry(buf32, fp, sizeof(u32));
 384                 if (rc) {
 385                         printk(KERN_ERR "SELinux: avtab: truncated entry\n");
 386                         return rc;
 387                 }
 388                 items2 = le32_to_cpu(buf32[0]);
 389                 if (items2 > ARRAY_SIZE(buf32)) {
 390                         printk(KERN_ERR "SELinux: avtab: entry overflow\n");
 391                         return -EINVAL;
 392
 393                 }
 394                 rc = next_entry(buf32, fp, sizeof(u32)*items2);
 395                 if (rc) {
 396                         printk(KERN_ERR "SELinux: avtab: truncated entry\n");
 397                         return rc;
 398                 }
 399                 items = 0;
 400
 401                 val = le32_to_cpu(buf32[items++]);
 402                 key.source_type = (u16)val;
 403                 if (key.source_type != val) {
 404                         printk(KERN_ERR "SELinux: avtab: truncated source type\n");
 405                         return -EINVAL;
 406                 }
 407                 val = le32_to_cpu(buf32[items++]);
 408                 key.target_type = (u16)val;
 409                 if (key.target_type != val) {
 410                         printk(KERN_ERR "SELinux: avtab: truncated target type\n");
 411                         return -EINVAL;
 412                 }
 413                 val = le32_to_cpu(buf32[items++]);
 414                 key.target_class = (u16)val;
 415                 if (key.target_class != val) {
 416                         printk(KERN_ERR "SELinux: avtab: truncated target class\n");
 417                         return -EINVAL;
 418                 }
 419
 420                 val = le32_to_cpu(buf32[items++]);
 421                 enabled = (val & AVTAB_ENABLED_OLD) ? AVTAB_ENABLED : 0;
 422
 423                 if (!(val & (AVTAB_AV | AVTAB_TYPE))) {
 424                         printk(KERN_ERR "SELinux: avtab: null entry\n");
 425                         return -EINVAL;
 426                 }
 427                 if ((val & AVTAB_AV) &&
 428                     (val & AVTAB_TYPE)) {
 429                         printk(KERN_ERR "SELinux: avtab: entry has both access vectors and types\n");
 430                         return -EINVAL;
 431                 }
 432
 433                 for (i = 0; i < ARRAY_SIZE(spec_order); i++) {
 434                         if (val & spec_order[i]) {
 435                                 key.specified = spec_order[i] | enabled;
 436                                 datum.data = le32_to_cpu(buf32[items++]);
 437                                 rc = insertf(a, &key, &datum, p);
 438                                 if (rc)
 439                                         return rc;
 440                         }
 441                 }
 442
 443                 if (items != items2) {
 444                         printk(KERN_ERR "SELinux: avtab: entry only had %d items, expected %d\n", items2, items);
 445                         return -EINVAL;
 446                 }
 447                 return 0;
 448         }
 449
 450         rc = next_entry(buf16, fp, sizeof(u16)*4);
 451         if (rc) {
 452                 printk(KERN_ERR "SELinux: avtab: truncated entry\n");
 453                 return rc;
 454         }
 455
 456         items = 0;
 457         key.source_type = le16_to_cpu(buf16[items++]);
 458         key.target_type = le16_to_cpu(buf16[items++]);
 459         key.target_class = le16_to_cpu(buf16[items++]);
 460         key.specified = le16_to_cpu(buf16[items++]);
 461
 462         if (!policydb_type_isvalid(pol, key.source_type) ||
 463             !policydb_type_isvalid(pol, key.target_type) ||
 464             !policydb_class_isvalid(pol, key.target_class)) {
 465                 printk(KERN_ERR "SELinux: avtab: invalid type or class\n");
 466                 return -EINVAL;
 467         }
 468
 469         set = 0;
 470         for (i = 0; i < ARRAY_SIZE(spec_order); i++) {
 471                 if (key.specified & spec_order[i])
 472                         set++;
 473         }
 474         if (!set || set > 1) {
 475                 printk(KERN_ERR "SELinux:  avtab:  more than one specifier\n");
 476                 return -EINVAL;
 477         }
 478
 479         rc = next_entry(buf32, fp, sizeof(u32));
 480         if (rc) {
 481                 printk(KERN_ERR "SELinux: avtab: truncated entry\n");
 482                 return rc;
 483         }
 484         datum.data = le32_to_cpu(*buf32);
 485         if ((key.specified & AVTAB_TYPE) &&
 486             !policydb_type_isvalid(pol, datum.data)) {
 487                 printk(KERN_ERR "SELinux: avtab: invalid type\n");
 488                 return -EINVAL;
 489         }
 490         return insertf(a, &key, &datum, p);
 491 }
 492
 493 static int avtab_insertf(struct avtab *a, struct avtab_key *k,
 494                          struct avtab_datum *d, void *p)
 495 {
 496         return avtab_insert(a, k, d);
 497 }
 498
 499 int avtab_read(struct avtab *a, void *fp, struct policydb *pol)
 500 {
 501         int rc;
 502         __le32 buf[1];
 503         u32 nel, i;
 504
 505
 506         rc = next_entry(buf, fp, sizeof(u32));
 507         if (rc < 0) {
 508                 printk(KERN_ERR "SELinux: avtab: truncated table\n");
 509                 goto bad;
 510         }
 511         nel = le32_to_cpu(buf[0]);
 512         if (!nel) {
 513                 printk(KERN_ERR "SELinux: avtab: table is empty\n");
 514                 rc = -EINVAL;
 515                 goto bad;
 516         }
 517
 518         rc = avtab_alloc(a, nel);
 519         if (rc)
 520                 goto bad;
 521
 522         for (i = 0; i < nel; i++) {
 523                 rc = avtab_read_item(a, fp, pol, avtab_insertf, NULL);
 524                 if (rc) {
 525                         if (rc == -ENOMEM)
 526                                 printk(KERN_ERR "SELinux: avtab: out of memory\n");
 527                         else if (rc == -EEXIST)
 528                                 printk(KERN_ERR "SELinux: avtab: duplicate entry\n");
 529
 530                         goto bad;
 531                 }
 532         }
 533
 534         rc = 0;
 535 out:
 536         return rc;
 537
 538 bad:
 539         avtab_destroy(a);
 540         goto out;
 541 }
 542
 543 int avtab_write_item(struct policydb *p, struct avtab_node *cur, void *fp)
 544 {
 545         __le16 buf16[4];
 546         __le32 buf32[1];
 547         int rc;
 548
 549         buf16[0] = cpu_to_le16(cur->key.source_type);
 550         buf16[1] = cpu_to_le16(cur->key.target_type);
 551         buf16[2] = cpu_to_le16(cur->key.target_class);
 552         buf16[3] = cpu_to_le16(cur->key.specified);
 553         rc = put_entry(buf16, sizeof(u16), 4, fp);
 554         if (rc)
 555                 return rc;
 556         buf32[0] = cpu_to_le32(cur->datum.data);
 557         rc = put_entry(buf32, sizeof(u32), 1, fp);
 558         if (rc)
 559                 return rc;
 560         return 0;
 561 }
 562
 563 int avtab_write(struct policydb *p, struct avtab *a, void *fp)
 564 {
 565         unsigned int i;
 566         int rc = 0;
 567         struct avtab_node *cur;
 568         __le32 buf[1];
 569
 570         buf[0] = cpu_to_le32(a->nel);
 571         rc = put_entry(buf, sizeof(u32), 1, fp);
 572         if (rc)
 573                 return rc;
 574
 575         for (i = 0; i < a->nslot; i++) {
 576                 for (cur = flex_array_get_ptr(a->htable, i); cur;
 577                      cur = cur->next) {
 578                         rc = avtab_write_item(p, cur, fp);
 579                         if (rc)
 580                                 return rc;
 581                 }
 582         }
 583
 584         return rc;
 585 }
 586 void avtab_cache_init(void)
 587 {
 588         avtab_node_cachep = kmem_cache_create("avtab_node",
 589                                               sizeof(struct avtab_node),
 590                                               0, SLAB_PANIC, NULL);
 591 }
 592
 593 void avtab_cache_destroy(void)
 594 {
 595         kmem_cache_destroy(avtab_node_cachep);
 596 }