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 static inline int avtab_hash(struct avtab_key *keyp, u16 mask)
  29 {
  30         return ((keyp->target_class + (keyp->target_type << 2) +
  31                  (keyp->source_type << 9)) & mask);
  32 }
  33
  34 static struct avtab_node*
  35 avtab_insert_node(struct avtab *h, int hvalue,
  36                   struct avtab_node * prev, struct avtab_node * cur,
  37                   struct avtab_key *key, struct avtab_datum *datum)
  38 {
  39         struct avtab_node * newnode;
  40         newnode = kmem_cache_zalloc(avtab_node_cachep, GFP_KERNEL);
  41         if (newnode == NULL)
  42                 return NULL;
  43         newnode->key = *key;
  44         newnode->datum = *datum;
  45         if (prev) {
  46                 newnode->next = prev->next;
  47                 prev->next = newnode;
  48         } else {
  49                 newnode->next = h->htable[hvalue];
  50                 h->htable[hvalue] = newnode;
  51         }
  52
  53         h->nel++;
  54         return newnode;
  55 }
  56
  57 static int avtab_insert(struct avtab *h, struct avtab_key *key, struct avtab_datum *datum)
  58 {
  59         int hvalue;
  60         struct avtab_node *prev, *cur, *newnode;
  61         u16 specified = key->specified & ~(AVTAB_ENABLED|AVTAB_ENABLED_OLD);
  62
  63         if (!h || !h->htable)
  64                 return -EINVAL;
  65
  66         hvalue = avtab_hash(key, h->mask);
  67         for (prev = NULL, cur = h->htable[hvalue];
  68              cur;
  69              prev = cur, cur = cur->next) {
  70                 if (key->source_type == cur->key.source_type &&
  71                     key->target_type == cur->key.target_type &&
  72                     key->target_class == cur->key.target_class &&
  73                     (specified & cur->key.specified))
  74                         return -EEXIST;
  75                 if (key->source_type < cur->key.source_type)
  76                         break;
  77                 if (key->source_type == cur->key.source_type &&
  78                     key->target_type < cur->key.target_type)
  79                         break;
  80                 if (key->source_type == cur->key.source_type &&
  81                     key->target_type == cur->key.target_type &&
  82                     key->target_class < cur->key.target_class)
  83                         break;
  84         }
  85
  86         newnode = avtab_insert_node(h, hvalue, prev, cur, key, datum);
  87         if(!newnode)
  88                 return -ENOMEM;
  89
  90         return 0;
  91 }
  92
  93 /* Unlike avtab_insert(), this function allow multiple insertions of the same
  94  * key/specified mask into the table, as needed by the conditional avtab.
  95  * It also returns a pointer to the node inserted.
  96  */
  97 struct avtab_node *
  98 avtab_insert_nonunique(struct avtab * h, struct avtab_key * key, struct avtab_datum * datum)
  99 {
 100         int hvalue;
 101         struct avtab_node *prev, *cur, *newnode;
 102         u16 specified = key->specified & ~(AVTAB_ENABLED|AVTAB_ENABLED_OLD);
 103
 104         if (!h || !h->htable)
 105                 return NULL;
 106         hvalue = avtab_hash(key, h->mask);
 107         for (prev = NULL, cur = h->htable[hvalue];
 108              cur;
 109              prev = cur, cur = cur->next) {
 110                 if (key->source_type == cur->key.source_type &&
 111                     key->target_type == cur->key.target_type &&
 112                     key->target_class == cur->key.target_class &&
 113                     (specified & cur->key.specified))
 114                         break;
 115                 if (key->source_type < cur->key.source_type)
 116                         break;
 117                 if (key->source_type == cur->key.source_type &&
 118                     key->target_type < cur->key.target_type)
 119                         break;
 120                 if (key->source_type == cur->key.source_type &&
 121                     key->target_type == cur->key.target_type &&
 122                     key->target_class < cur->key.target_class)
 123                         break;
 124         }
 125         newnode = avtab_insert_node(h, hvalue, prev, cur, key, datum);
 126
 127         return newnode;
 128 }
 129
 130 struct avtab_datum *avtab_search(struct avtab *h, struct avtab_key *key)
 131 {
 132         int hvalue;
 133         struct avtab_node *cur;
 134         u16 specified = key->specified & ~(AVTAB_ENABLED|AVTAB_ENABLED_OLD);
 135
 136         if (!h || !h->htable)
 137                 return NULL;
 138
 139         hvalue = avtab_hash(key, h->mask);
 140         for (cur = h->htable[hvalue]; cur; cur = cur->next) {
 141                 if (key->source_type == cur->key.source_type &&
 142                     key->target_type == cur->key.target_type &&
 143                     key->target_class == cur->key.target_class &&
 144                     (specified & cur->key.specified))
 145                         return &cur->datum;
 146
 147                 if (key->source_type < cur->key.source_type)
 148                         break;
 149                 if (key->source_type == cur->key.source_type &&
 150                     key->target_type < cur->key.target_type)
 151                         break;
 152                 if (key->source_type == cur->key.source_type &&
 153                     key->target_type == cur->key.target_type &&
 154                     key->target_class < cur->key.target_class)
 155                         break;
 156         }
 157
 158         return NULL;
 159 }
 160
 161 /* This search function returns a node pointer, and can be used in
 162  * conjunction with avtab_search_next_node()
 163  */
 164 struct avtab_node*
 165 avtab_search_node(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 = h->htable[hvalue]; cur; cur = cur->next) {
 176                 if (key->source_type == cur->key.source_type &&
 177                     key->target_type == cur->key.target_type &&
 178                     key->target_class == cur->key.target_class &&
 179                     (specified & cur->key.specified))
 180                         return cur;
 181
 182                 if (key->source_type < cur->key.source_type)
 183                         break;
 184                 if (key->source_type == cur->key.source_type &&
 185                     key->target_type < cur->key.target_type)
 186                         break;
 187                 if (key->source_type == cur->key.source_type &&
 188                     key->target_type == cur->key.target_type &&
 189                     key->target_class < cur->key.target_class)
 190                         break;
 191         }
 192         return NULL;
 193 }
 194
 195 struct avtab_node*
 196 avtab_search_node_next(struct avtab_node *node, int specified)
 197 {
 198         struct avtab_node *cur;
 199
 200         if (!node)
 201                 return NULL;
 202
 203         specified &= ~(AVTAB_ENABLED|AVTAB_ENABLED_OLD);
 204         for (cur = node->next; cur; cur = cur->next) {
 205                 if (node->key.source_type == cur->key.source_type &&
 206                     node->key.target_type == cur->key.target_type &&
 207                     node->key.target_class == cur->key.target_class &&
 208                     (specified & cur->key.specified))
 209                         return cur;
 210
 211                 if (node->key.source_type < cur->key.source_type)
 212                         break;
 213                 if (node->key.source_type == cur->key.source_type &&
 214                     node->key.target_type < cur->key.target_type)
 215                         break;
 216                 if (node->key.source_type == cur->key.source_type &&
 217                     node->key.target_type == cur->key.target_type &&
 218                     node->key.target_class < cur->key.target_class)
 219                         break;
 220         }
 221         return NULL;
 222 }
 223
 224 void avtab_destroy(struct avtab *h)
 225 {
 226         int i;
 227         struct avtab_node *cur, *temp;
 228
 229         if (!h || !h->htable)
 230                 return;
 231
 232         for (i = 0; i < h->nslot; i++) {
 233                 cur = h->htable[i];
 234                 while (cur != NULL) {
 235                         temp = cur;
 236                         cur = cur->next;
 237                         kmem_cache_free(avtab_node_cachep, temp);
 238                 }
 239                 h->htable[i] = NULL;
 240         }
 241         kfree(h->htable);
 242         h->htable = NULL;
 243         h->nslot = 0;
 244         h->mask = 0;
 245 }
 246
 247 int avtab_init(struct avtab *h)
 248 {
 249         h->htable = NULL;
 250         h->nel = 0;
 251         return 0;
 252 }
 253
 254 int avtab_alloc(struct avtab *h, u32 nrules)
 255 {
 256         u16 mask = 0;
 257         u32 shift = 0;
 258         u32 work = nrules;
 259         u32 nslot = 0;
 260
 261         if (nrules == 0)
 262                 goto avtab_alloc_out;
 263
 264         while (work) {
 265                 work  = work >> 1;
 266                 shift++;
 267         }
 268         if (shift > 2)
 269                 shift = shift - 2;
 270         nslot = 1 << shift;
 271         if (nslot > MAX_AVTAB_SIZE)
 272                 nslot = MAX_AVTAB_SIZE;
 273         mask = nslot - 1;
 274
 275         h->htable = kcalloc(nslot, sizeof(*(h->htable)), GFP_KERNEL);
 276         if (!h->htable)
 277                 return -ENOMEM;
 278
 279  avtab_alloc_out:
 280         h->nel = 0;
 281         h->nslot = nslot;
 282         h->mask = mask;
 283         printk(KERN_DEBUG "SELinux:%d avtab hash slots allocated."
 284                "Num of rules:%d\n", h->nslot, nrules);
 285         return 0;
 286 }
 287
 288 void avtab_hash_eval(struct avtab *h, char *tag)
 289 {
 290         int i, chain_len, slots_used, max_chain_len;
 291         unsigned long long chain2_len_sum;
 292         struct avtab_node *cur;
 293
 294         slots_used = 0;
 295         max_chain_len = 0;
 296         chain2_len_sum = 0;
 297         for (i = 0; i < h->nslot; i++) {
 298                 cur = h->htable[i];
 299                 if (cur) {
 300                         slots_used++;
 301                         chain_len = 0;
 302                         while (cur) {
 303                                 chain_len++;
 304                                 cur = cur->next;
 305                         }
 306
 307                         if (chain_len > max_chain_len)
 308                                 max_chain_len = chain_len;
 309                         chain2_len_sum += chain_len * chain_len;
 310                 }
 311         }
 312
 313         printk(KERN_DEBUG "%s:  %d entries and %d/%d buckets used, longest "
 314                "chain length %d sum of chain length^2 %Lu\n",
 315                tag, h->nel, slots_used, h->nslot, max_chain_len,
 316                chain2_len_sum);
 317 }
 318
 319 static uint16_t spec_order[] = {
 320         AVTAB_ALLOWED,
 321         AVTAB_AUDITDENY,
 322         AVTAB_AUDITALLOW,
 323         AVTAB_TRANSITION,
 324         AVTAB_CHANGE,
 325         AVTAB_MEMBER
 326 };
 327
 328 int avtab_read_item(void *fp, u32 vers, struct avtab *a,
 329                     int (*insertf)(struct avtab *a, struct avtab_key *k,
 330                                    struct avtab_datum *d, void *p),
 331                     void *p)
 332 {
 333         __le16 buf16[4];
 334         u16 enabled;
 335         __le32 buf32[7];
 336         u32 items, items2, val;
 337         struct avtab_key key;
 338         struct avtab_datum datum;
 339         int i, rc;
 340
 341         memset(&key, 0, sizeof(struct avtab_key));
 342         memset(&datum, 0, sizeof(struct avtab_datum));
 343
 344         if (vers < POLICYDB_VERSION_AVTAB) {
 345                 rc = next_entry(buf32, fp, sizeof(u32));
 346                 if (rc < 0) {
 347                         printk(KERN_ERR "security: avtab: truncated entry\n");
 348                         return -1;
 349                 }
 350                 items2 = le32_to_cpu(buf32[0]);
 351                 if (items2 > ARRAY_SIZE(buf32)) {
 352                         printk(KERN_ERR "security: avtab: entry overflow\n");
 353                         return -1;
 354
 355                 }
 356                 rc = next_entry(buf32, fp, sizeof(u32)*items2);
 357                 if (rc < 0) {
 358                         printk(KERN_ERR "security: avtab: truncated entry\n");
 359                         return -1;
 360                 }
 361                 items = 0;
 362
 363                 val = le32_to_cpu(buf32[items++]);
 364                 key.source_type = (u16)val;
 365                 if (key.source_type != val) {
 366                         printk("security: avtab: truncated source type\n");
 367                         return -1;
 368                 }
 369                 val = le32_to_cpu(buf32[items++]);
 370                 key.target_type = (u16)val;
 371                 if (key.target_type != val) {
 372                         printk("security: avtab: truncated target type\n");
 373                         return -1;
 374                 }
 375                 val = le32_to_cpu(buf32[items++]);
 376                 key.target_class = (u16)val;
 377                 if (key.target_class != val) {
 378                         printk("security: avtab: truncated target class\n");
 379                         return -1;
 380                 }
 381
 382                 val = le32_to_cpu(buf32[items++]);
 383                 enabled = (val & AVTAB_ENABLED_OLD) ? AVTAB_ENABLED : 0;
 384
 385                 if (!(val & (AVTAB_AV | AVTAB_TYPE))) {
 386                         printk("security: avtab: null entry\n");
 387                         return -1;
 388                 }
 389                 if ((val & AVTAB_AV) &&
 390                     (val & AVTAB_TYPE)) {
 391                         printk("security: avtab: entry has both access vectors and types\n");
 392                         return -1;
 393                 }
 394
 395                 for (i = 0; i < ARRAY_SIZE(spec_order); i++) {
 396                         if (val & spec_order[i]) {
 397                                 key.specified = spec_order[i] | enabled;
 398                                 datum.data = le32_to_cpu(buf32[items++]);
 399                                 rc = insertf(a, &key, &datum, p);
 400                                 if (rc) return rc;
 401                         }
 402                 }
 403
 404                 if (items != items2) {
 405                         printk("security: avtab: entry only had %d items, expected %d\n", items2, items);
 406                         return -1;
 407                 }
 408                 return 0;
 409         }
 410
 411         rc = next_entry(buf16, fp, sizeof(u16)*4);
 412         if (rc < 0) {
 413                 printk("security: avtab: truncated entry\n");
 414                 return -1;
 415         }
 416
 417         items = 0;
 418         key.source_type = le16_to_cpu(buf16[items++]);
 419         key.target_type = le16_to_cpu(buf16[items++]);
 420         key.target_class = le16_to_cpu(buf16[items++]);
 421         key.specified = le16_to_cpu(buf16[items++]);
 422
 423         rc = next_entry(buf32, fp, sizeof(u32));
 424         if (rc < 0) {
 425                 printk("security: avtab: truncated entry\n");
 426                 return -1;
 427         }
 428         datum.data = le32_to_cpu(*buf32);
 429         return insertf(a, &key, &datum, p);
 430 }
 431
 432 static int avtab_insertf(struct avtab *a, struct avtab_key *k,
 433                          struct avtab_datum *d, void *p)
 434 {
 435         return avtab_insert(a, k, d);
 436 }
 437
 438 int avtab_read(struct avtab *a, void *fp, u32 vers)
 439 {
 440         int rc;
 441         __le32 buf[1];
 442         u32 nel, i;
 443
 444
 445         rc = next_entry(buf, fp, sizeof(u32));
 446         if (rc < 0) {
 447                 printk(KERN_ERR "security: avtab: truncated table\n");
 448                 goto bad;
 449         }
 450         nel = le32_to_cpu(buf[0]);
 451         if (!nel) {
 452                 printk(KERN_ERR "security: avtab: table is empty\n");
 453                 rc = -EINVAL;
 454                 goto bad;
 455         }
 456
 457         rc = avtab_alloc(a, nel);
 458         if (rc)
 459                 goto bad;
 460
 461         for (i = 0; i < nel; i++) {
 462                 rc = avtab_read_item(fp,vers, a, avtab_insertf, NULL);
 463                 if (rc) {
 464                         if (rc == -ENOMEM)
 465                                 printk(KERN_ERR "security: avtab: out of memory\n");
 466                         else if (rc == -EEXIST)
 467                                 printk(KERN_ERR "security: avtab: duplicate entry\n");
 468                         else
 469                                 rc = -EINVAL;
 470                         goto bad;
 471                 }
 472         }
 473
 474         rc = 0;
 475 out:
 476         return rc;
 477
 478 bad:
 479         avtab_destroy(a);
 480         goto out;
 481 }
 482
 483 void avtab_cache_init(void)
 484 {
 485         avtab_node_cachep = kmem_cache_create("avtab_node",
 486                                               sizeof(struct avtab_node),
 487                                               0, SLAB_PANIC, NULL);
 488 }
 489
 490 void avtab_cache_destroy(void)
 491 {
 492         kmem_cache_destroy (avtab_node_cachep);
 493 }