release/src-rt-6.x.4708/linux/linux-2.6.36/security/selinux/ss/conditional.c

   1 /* Authors: Karl MacMillan <kmacmillan@tresys.com>
   2  *          Frank Mayer <mayerf@tresys.com>
   3  *
   4  * Copyright (C) 2003 - 2004 Tresys Technology, LLC
   5  *      This program is free software; you can redistribute it and/or modify
   6  *      it under the terms of the GNU General Public License as published by
   7  *      the Free Software Foundation, version 2.
   8  */
   9
  10 #include <linux/kernel.h>
  11 #include <linux/errno.h>
  12 #include <linux/string.h>
  13 #include <linux/spinlock.h>
  14 #include <linux/slab.h>
  15
  16 #include "security.h"
  17 #include "conditional.h"
  18
  19 /*
  20  * cond_evaluate_expr evaluates a conditional expr
  21  * in reverse polish notation. It returns true (1), false (0),
  22  * or undefined (-1). Undefined occurs when the expression
  23  * exceeds the stack depth of COND_EXPR_MAXDEPTH.
  24  */
  25 static int cond_evaluate_expr(struct policydb *p, struct cond_expr *expr)
  26 {
  27
  28         struct cond_expr *cur;
  29         int s[COND_EXPR_MAXDEPTH];
  30         int sp = -1;
  31
  32         for (cur = expr; cur; cur = cur->next) {
  33                 switch (cur->expr_type) {
  34                 case COND_BOOL:
  35                         if (sp == (COND_EXPR_MAXDEPTH - 1))
  36                                 return -1;
  37                         sp++;
  38                         s[sp] = p->bool_val_to_struct[cur->bool - 1]->state;
  39                         break;
  40                 case COND_NOT:
  41                         if (sp < 0)
  42                                 return -1;
  43                         s[sp] = !s[sp];
  44                         break;
  45                 case COND_OR:
  46                         if (sp < 1)
  47                                 return -1;
  48                         sp--;
  49                         s[sp] |= s[sp + 1];
  50                         break;
  51                 case COND_AND:
  52                         if (sp < 1)
  53                                 return -1;
  54                         sp--;
  55                         s[sp] &= s[sp + 1];
  56                         break;
  57                 case COND_XOR:
  58                         if (sp < 1)
  59                                 return -1;
  60                         sp--;
  61                         s[sp] ^= s[sp + 1];
  62                         break;
  63                 case COND_EQ:
  64                         if (sp < 1)
  65                                 return -1;
  66                         sp--;
  67                         s[sp] = (s[sp] == s[sp + 1]);
  68                         break;
  69                 case COND_NEQ:
  70                         if (sp < 1)
  71                                 return -1;
  72                         sp--;
  73                         s[sp] = (s[sp] != s[sp + 1]);
  74                         break;
  75                 default:
  76                         return -1;
  77                 }
  78         }
  79         return s[0];
  80 }
  81
  82 /*
  83  * evaluate_cond_node evaluates the conditional stored in
  84  * a struct cond_node and if the result is different than the
  85  * current state of the node it sets the rules in the true/false
  86  * list appropriately. If the result of the expression is undefined
  87  * all of the rules are disabled for safety.
  88  */
  89 int evaluate_cond_node(struct policydb *p, struct cond_node *node)
  90 {
  91         int new_state;
  92         struct cond_av_list *cur;
  93
  94         new_state = cond_evaluate_expr(p, node->expr);
  95         if (new_state != node->cur_state) {
  96                 node->cur_state = new_state;
  97                 if (new_state == -1)
  98                         printk(KERN_ERR "SELinux: expression result was undefined - disabling all rules.\n");
  99                 /* turn the rules on or off */
 100                 for (cur = node->true_list; cur; cur = cur->next) {
 101                         if (new_state <= 0)
 102                                 cur->node->key.specified &= ~AVTAB_ENABLED;
 103                         else
 104                                 cur->node->key.specified |= AVTAB_ENABLED;
 105                 }
 106
 107                 for (cur = node->false_list; cur; cur = cur->next) {
 108                         /* -1 or 1 */
 109                         if (new_state)
 110                                 cur->node->key.specified &= ~AVTAB_ENABLED;
 111                         else
 112                                 cur->node->key.specified |= AVTAB_ENABLED;
 113                 }
 114         }
 115         return 0;
 116 }
 117
 118 int cond_policydb_init(struct policydb *p)
 119 {
 120         int rc;
 121
 122         p->bool_val_to_struct = NULL;
 123         p->cond_list = NULL;
 124
 125         rc = avtab_init(&p->te_cond_avtab);
 126         if (rc)
 127                 return rc;
 128
 129         return 0;
 130 }
 131
 132 static void cond_av_list_destroy(struct cond_av_list *list)
 133 {
 134         struct cond_av_list *cur, *next;
 135         for (cur = list; cur; cur = next) {
 136                 next = cur->next;
 137                 /* the avtab_ptr_t node is destroy by the avtab */
 138                 kfree(cur);
 139         }
 140 }
 141
 142 static void cond_node_destroy(struct cond_node *node)
 143 {
 144         struct cond_expr *cur_expr, *next_expr;
 145
 146         for (cur_expr = node->expr; cur_expr; cur_expr = next_expr) {
 147                 next_expr = cur_expr->next;
 148                 kfree(cur_expr);
 149         }
 150         cond_av_list_destroy(node->true_list);
 151         cond_av_list_destroy(node->false_list);
 152         kfree(node);
 153 }
 154
 155 static void cond_list_destroy(struct cond_node *list)
 156 {
 157         struct cond_node *next, *cur;
 158
 159         if (list == NULL)
 160                 return;
 161
 162         for (cur = list; cur; cur = next) {
 163                 next = cur->next;
 164                 cond_node_destroy(cur);
 165         }
 166 }
 167
 168 void cond_policydb_destroy(struct policydb *p)
 169 {
 170         kfree(p->bool_val_to_struct);
 171         avtab_destroy(&p->te_cond_avtab);
 172         cond_list_destroy(p->cond_list);
 173 }
 174
 175 int cond_init_bool_indexes(struct policydb *p)
 176 {
 177         kfree(p->bool_val_to_struct);
 178         p->bool_val_to_struct = (struct cond_bool_datum **)
 179                 kmalloc(p->p_bools.nprim * sizeof(struct cond_bool_datum *), GFP_KERNEL);
 180         if (!p->bool_val_to_struct)
 181                 return -1;
 182         return 0;
 183 }
 184
 185 int cond_destroy_bool(void *key, void *datum, void *p)
 186 {
 187         kfree(key);
 188         kfree(datum);
 189         return 0;
 190 }
 191
 192 int cond_index_bool(void *key, void *datum, void *datap)
 193 {
 194         struct policydb *p;
 195         struct cond_bool_datum *booldatum;
 196
 197         booldatum = datum;
 198         p = datap;
 199
 200         if (!booldatum->value || booldatum->value > p->p_bools.nprim)
 201                 return -EINVAL;
 202
 203         p->p_bool_val_to_name[booldatum->value - 1] = key;
 204         p->bool_val_to_struct[booldatum->value - 1] = booldatum;
 205
 206         return 0;
 207 }
 208
 209 static int bool_isvalid(struct cond_bool_datum *b)
 210 {
 211         if (!(b->state == 0 || b->state == 1))
 212                 return 0;
 213         return 1;
 214 }
 215
 216 int cond_read_bool(struct policydb *p, struct hashtab *h, void *fp)
 217 {
 218         char *key = NULL;
 219         struct cond_bool_datum *booldatum;
 220         __le32 buf[3];
 221         u32 len;
 222         int rc;
 223
 224         booldatum = kzalloc(sizeof(struct cond_bool_datum), GFP_KERNEL);
 225         if (!booldatum)
 226                 return -ENOMEM;
 227
 228         rc = next_entry(buf, fp, sizeof buf);
 229         if (rc)
 230                 goto err;
 231
 232         booldatum->value = le32_to_cpu(buf[0]);
 233         booldatum->state = le32_to_cpu(buf[1]);
 234
 235         rc = -EINVAL;
 236         if (!bool_isvalid(booldatum))
 237                 goto err;
 238
 239         len = le32_to_cpu(buf[2]);
 240
 241         rc = -ENOMEM;
 242         key = kmalloc(len + 1, GFP_KERNEL);
 243         if (!key)
 244                 goto err;
 245         rc = next_entry(key, fp, len);
 246         if (rc)
 247                 goto err;
 248         key[len] = '\0';
 249         rc = hashtab_insert(h, key, booldatum);
 250         if (rc)
 251                 goto err;
 252
 253         return 0;
 254 err:
 255         cond_destroy_bool(key, booldatum, NULL);
 256         return rc;
 257 }
 258
 259 struct cond_insertf_data {
 260         struct policydb *p;
 261         struct cond_av_list *other;
 262         struct cond_av_list *head;
 263         struct cond_av_list *tail;
 264 };
 265
 266 static int cond_insertf(struct avtab *a, struct avtab_key *k, struct avtab_datum *d, void *ptr)
 267 {
 268         struct cond_insertf_data *data = ptr;
 269         struct policydb *p = data->p;
 270         struct cond_av_list *other = data->other, *list, *cur;
 271         struct avtab_node *node_ptr;
 272         u8 found;
 273         int rc = -EINVAL;
 274
 275         /*
 276          * For type rules we have to make certain there aren't any
 277          * conflicting rules by searching the te_avtab and the
 278          * cond_te_avtab.
 279          */
 280         if (k->specified & AVTAB_TYPE) {
 281                 if (avtab_search(&p->te_avtab, k)) {
 282                         printk(KERN_ERR "SELinux: type rule already exists outside of a conditional.\n");
 283                         goto err;
 284                 }
 285                 /*
 286                  * If we are reading the false list other will be a pointer to
 287                  * the true list. We can have duplicate entries if there is only
 288                  * 1 other entry and it is in our true list.
 289                  *
 290                  * If we are reading the true list (other == NULL) there shouldn't
 291                  * be any other entries.
 292                  */
 293                 if (other) {
 294                         node_ptr = avtab_search_node(&p->te_cond_avtab, k);
 295                         if (node_ptr) {
 296                                 if (avtab_search_node_next(node_ptr, k->specified)) {
 297                                         printk(KERN_ERR "SELinux: too many conflicting type rules.\n");
 298                                         goto err;
 299                                 }
 300                                 found = 0;
 301                                 for (cur = other; cur; cur = cur->next) {
 302                                         if (cur->node == node_ptr) {
 303                                                 found = 1;
 304                                                 break;
 305                                         }
 306                                 }
 307                                 if (!found) {
 308                                         printk(KERN_ERR "SELinux: conflicting type rules.\n");
 309                                         goto err;
 310                                 }
 311                         }
 312                 } else {
 313                         if (avtab_search(&p->te_cond_avtab, k)) {
 314                                 printk(KERN_ERR "SELinux: conflicting type rules when adding type rule for true.\n");
 315                                 goto err;
 316                         }
 317                 }
 318         }
 319
 320         node_ptr = avtab_insert_nonunique(&p->te_cond_avtab, k, d);
 321         if (!node_ptr) {
 322                 printk(KERN_ERR "SELinux: could not insert rule.\n");
 323                 rc = -ENOMEM;
 324                 goto err;
 325         }
 326
 327         list = kzalloc(sizeof(struct cond_av_list), GFP_KERNEL);
 328         if (!list) {
 329                 rc = -ENOMEM;
 330                 goto err;
 331         }
 332
 333         list->node = node_ptr;
 334         if (!data->head)
 335                 data->head = list;
 336         else
 337                 data->tail->next = list;
 338         data->tail = list;
 339         return 0;
 340
 341 err:
 342         cond_av_list_destroy(data->head);
 343         data->head = NULL;
 344         return rc;
 345 }
 346
 347 static int cond_read_av_list(struct policydb *p, void *fp, struct cond_av_list **ret_list, struct cond_av_list *other)
 348 {
 349         int i, rc;
 350         __le32 buf[1];
 351         u32 len;
 352         struct cond_insertf_data data;
 353
 354         *ret_list = NULL;
 355
 356         len = 0;
 357         rc = next_entry(buf, fp, sizeof(u32));
 358         if (rc)
 359                 return rc;
 360
 361         len = le32_to_cpu(buf[0]);
 362         if (len == 0)
 363                 return 0;
 364
 365         data.p = p;
 366         data.other = other;
 367         data.head = NULL;
 368         data.tail = NULL;
 369         for (i = 0; i < len; i++) {
 370                 rc = avtab_read_item(&p->te_cond_avtab, fp, p, cond_insertf,
 371                                      &data);
 372                 if (rc)
 373                         return rc;
 374         }
 375
 376         *ret_list = data.head;
 377         return 0;
 378 }
 379
 380 static int expr_isvalid(struct policydb *p, struct cond_expr *expr)
 381 {
 382         if (expr->expr_type <= 0 || expr->expr_type > COND_LAST) {
 383                 printk(KERN_ERR "SELinux: conditional expressions uses unknown operator.\n");
 384                 return 0;
 385         }
 386
 387         if (expr->bool > p->p_bools.nprim) {
 388                 printk(KERN_ERR "SELinux: conditional expressions uses unknown bool.\n");
 389                 return 0;
 390         }
 391         return 1;
 392 }
 393
 394 static int cond_read_node(struct policydb *p, struct cond_node *node, void *fp)
 395 {
 396         __le32 buf[2];
 397         u32 len, i;
 398         int rc;
 399         struct cond_expr *expr = NULL, *last = NULL;
 400
 401         rc = next_entry(buf, fp, sizeof(u32));
 402         if (rc)
 403                 return rc;
 404
 405         node->cur_state = le32_to_cpu(buf[0]);
 406
 407         len = 0;
 408         rc = next_entry(buf, fp, sizeof(u32));
 409         if (rc)
 410                 return rc;
 411
 412         /* expr */
 413         len = le32_to_cpu(buf[0]);
 414
 415         for (i = 0; i < len; i++) {
 416                 rc = next_entry(buf, fp, sizeof(u32) * 2);
 417                 if (rc)
 418                         goto err;
 419
 420                 rc = -ENOMEM;
 421                 expr = kzalloc(sizeof(struct cond_expr), GFP_KERNEL);
 422                 if (!expr)
 423                         goto err;
 424
 425                 expr->expr_type = le32_to_cpu(buf[0]);
 426                 expr->bool = le32_to_cpu(buf[1]);
 427
 428                 if (!expr_isvalid(p, expr)) {
 429                         rc = -EINVAL;
 430                         kfree(expr);
 431                         goto err;
 432                 }
 433
 434                 if (i == 0)
 435                         node->expr = expr;
 436                 else
 437                         last->next = expr;
 438                 last = expr;
 439         }
 440
 441         rc = cond_read_av_list(p, fp, &node->true_list, NULL);
 442         if (rc)
 443                 goto err;
 444         rc = cond_read_av_list(p, fp, &node->false_list, node->true_list);
 445         if (rc)
 446                 goto err;
 447         return 0;
 448 err:
 449         cond_node_destroy(node);
 450         return rc;
 451 }
 452
 453 int cond_read_list(struct policydb *p, void *fp)
 454 {
 455         struct cond_node *node, *last = NULL;
 456         __le32 buf[1];
 457         u32 i, len;
 458         int rc;
 459
 460         rc = next_entry(buf, fp, sizeof buf);
 461         if (rc)
 462                 return rc;
 463
 464         len = le32_to_cpu(buf[0]);
 465
 466         rc = avtab_alloc(&(p->te_cond_avtab), p->te_avtab.nel);
 467         if (rc)
 468                 goto err;
 469
 470         for (i = 0; i < len; i++) {
 471                 rc = -ENOMEM;
 472                 node = kzalloc(sizeof(struct cond_node), GFP_KERNEL);
 473                 if (!node)
 474                         goto err;
 475
 476                 rc = cond_read_node(p, node, fp);
 477                 if (rc)
 478                         goto err;
 479
 480                 if (i == 0)
 481                         p->cond_list = node;
 482                 else
 483                         last->next = node;
 484                 last = node;
 485         }
 486         return 0;
 487 err:
 488         cond_list_destroy(p->cond_list);
 489         p->cond_list = NULL;
 490         return rc;
 491 }
 492
 493 /* Determine whether additional permissions are granted by the conditional
 494  * av table, and if so, add them to the result
 495  */
 496 void cond_compute_av(struct avtab *ctab, struct avtab_key *key, struct av_decision *avd)
 497 {
 498         struct avtab_node *node;
 499
 500         if (!ctab || !key || !avd)
 501                 return;
 502
 503         for (node = avtab_search_node(ctab, key); node;
 504                                 node = avtab_search_node_next(node, key->specified)) {
 505                 if ((u16)(AVTAB_ALLOWED|AVTAB_ENABLED) ==
 506                     (node->key.specified & (AVTAB_ALLOWED|AVTAB_ENABLED)))
 507                         avd->allowed |= node->datum.data;
 508                 if ((u16)(AVTAB_AUDITDENY|AVTAB_ENABLED) ==
 509                     (node->key.specified & (AVTAB_AUDITDENY|AVTAB_ENABLED)))
 510                         /* Since a '0' in an auditdeny mask represents a
 511                          * permission we do NOT want to audit (dontaudit), we use
 512                          * the '&' operand to ensure that all '0's in the mask
 513                          * are retained (much unlike the allow and auditallow cases).
 514                          */
 515                         avd->auditdeny &= node->datum.data;
 516                 if ((u16)(AVTAB_AUDITALLOW|AVTAB_ENABLED) ==
 517                     (node->key.specified & (AVTAB_AUDITALLOW|AVTAB_ENABLED)))
 518                         avd->auditallow |= node->datum.data;
 519         }
 520         return;
 521 }