[PATCH] selinux: kfree cleanup
[linux-3.10.git] / 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 <asm/semaphore.h>
15 #include <linux/slab.h>
16
17 #include "security.h"
18 #include "conditional.h"
19
20 /*
21  * cond_evaluate_expr evaluates a conditional expr
22  * in reverse polish notation. It returns true (1), false (0),
23  * or undefined (-1). Undefined occurs when the expression
24  * exceeds the stack depth of COND_EXPR_MAXDEPTH.
25  */
26 static int cond_evaluate_expr(struct policydb *p, struct cond_expr *expr)
27 {
28
29         struct cond_expr *cur;
30         int s[COND_EXPR_MAXDEPTH];
31         int sp = -1;
32
33         for (cur = expr; cur != NULL; cur = cur->next) {
34                 switch (cur->expr_type) {
35                 case COND_BOOL:
36                         if (sp == (COND_EXPR_MAXDEPTH - 1))
37                                 return -1;
38                         sp++;
39                         s[sp] = p->bool_val_to_struct[cur->bool - 1]->state;
40                         break;
41                 case COND_NOT:
42                         if (sp < 0)
43                                 return -1;
44                         s[sp] = !s[sp];
45                         break;
46                 case COND_OR:
47                         if (sp < 1)
48                                 return -1;
49                         sp--;
50                         s[sp] |= s[sp + 1];
51                         break;
52                 case COND_AND:
53                         if (sp < 1)
54                                 return -1;
55                         sp--;
56                         s[sp] &= s[sp + 1];
57                         break;
58                 case COND_XOR:
59                         if (sp < 1)
60                                 return -1;
61                         sp--;
62                         s[sp] ^= s[sp + 1];
63                         break;
64                 case COND_EQ:
65                         if (sp < 1)
66                                 return -1;
67                         sp--;
68                         s[sp] = (s[sp] == s[sp + 1]);
69                         break;
70                 case COND_NEQ:
71                         if (sp < 1)
72                                 return -1;
73                         sp--;
74                         s[sp] = (s[sp] != s[sp + 1]);
75                         break;
76                 default:
77                         return -1;
78                 }
79         }
80         return s[0];
81 }
82
83 /*
84  * evaluate_cond_node evaluates the conditional stored in
85  * a struct cond_node and if the result is different than the
86  * current state of the node it sets the rules in the true/false
87  * list appropriately. If the result of the expression is undefined
88  * all of the rules are disabled for safety.
89  */
90 int evaluate_cond_node(struct policydb *p, struct cond_node *node)
91 {
92         int new_state;
93         struct cond_av_list* cur;
94
95         new_state = cond_evaluate_expr(p, node->expr);
96         if (new_state != node->cur_state) {
97                 node->cur_state = new_state;
98                 if (new_state == -1)
99                         printk(KERN_ERR "security: expression result was undefined - disabling all rules.\n");
100                 /* turn the rules on or off */
101                 for (cur = node->true_list; cur != NULL; cur = cur->next) {
102                         if (new_state <= 0) {
103                                 cur->node->datum.specified &= ~AVTAB_ENABLED;
104                         } else {
105                                 cur->node->datum.specified |= AVTAB_ENABLED;
106                         }
107                 }
108
109                 for (cur = node->false_list; cur != NULL; cur = cur->next) {
110                         /* -1 or 1 */
111                         if (new_state) {
112                                 cur->node->datum.specified &= ~AVTAB_ENABLED;
113                         } else {
114                                 cur->node->datum.specified |= AVTAB_ENABLED;
115                         }
116                 }
117         }
118         return 0;
119 }
120
121 int cond_policydb_init(struct policydb *p)
122 {
123         p->bool_val_to_struct = NULL;
124         p->cond_list = NULL;
125         if (avtab_init(&p->te_cond_avtab))
126                 return -1;
127
128         return 0;
129 }
130
131 static void cond_av_list_destroy(struct cond_av_list *list)
132 {
133         struct cond_av_list *cur, *next;
134         for (cur = list; cur != NULL; cur = next) {
135                 next = cur->next;
136                 /* the avtab_ptr_t node is destroy by the avtab */
137                 kfree(cur);
138         }
139 }
140
141 static void cond_node_destroy(struct cond_node *node)
142 {
143         struct cond_expr *cur_expr, *next_expr;
144
145         for (cur_expr = node->expr; cur_expr != NULL; cur_expr = next_expr) {
146                 next_expr = cur_expr->next;
147                 kfree(cur_expr);
148         }
149         cond_av_list_destroy(node->true_list);
150         cond_av_list_destroy(node->false_list);
151         kfree(node);
152 }
153
154 static void cond_list_destroy(struct cond_node *list)
155 {
156         struct cond_node *next, *cur;
157
158         if (list == NULL)
159                 return;
160
161         for (cur = list; cur != NULL; cur = next) {
162                 next = cur->next;
163                 cond_node_destroy(cur);
164         }
165 }
166
167 void cond_policydb_destroy(struct policydb *p)
168 {
169         kfree(p->bool_val_to_struct);
170         avtab_destroy(&p->te_cond_avtab);
171         cond_list_destroy(p->cond_list);
172 }
173
174 int cond_init_bool_indexes(struct policydb *p)
175 {
176         kfree(p->bool_val_to_struct);
177         p->bool_val_to_struct = (struct cond_bool_datum**)
178                 kmalloc(p->p_bools.nprim * sizeof(struct cond_bool_datum*), GFP_KERNEL);
179         if (!p->bool_val_to_struct)
180                 return -1;
181         return 0;
182 }
183
184 int cond_destroy_bool(void *key, void *datum, void *p)
185 {
186         kfree(key);
187         kfree(datum);
188         return 0;
189 }
190
191 int cond_index_bool(void *key, void *datum, void *datap)
192 {
193         struct policydb *p;
194         struct cond_bool_datum *booldatum;
195
196         booldatum = datum;
197         p = datap;
198
199         if (!booldatum->value || booldatum->value > p->p_bools.nprim)
200                 return -EINVAL;
201
202         p->p_bool_val_to_name[booldatum->value - 1] = key;
203         p->bool_val_to_struct[booldatum->value -1] = booldatum;
204
205         return 0;
206 }
207
208 static int bool_isvalid(struct cond_bool_datum *b)
209 {
210         if (!(b->state == 0 || b->state == 1))
211                 return 0;
212         return 1;
213 }
214
215 int cond_read_bool(struct policydb *p, struct hashtab *h, void *fp)
216 {
217         char *key = NULL;
218         struct cond_bool_datum *booldatum;
219         u32 buf[3], len;
220         int rc;
221
222         booldatum = kmalloc(sizeof(struct cond_bool_datum), GFP_KERNEL);
223         if (!booldatum)
224                 return -1;
225         memset(booldatum, 0, sizeof(struct cond_bool_datum));
226
227         rc = next_entry(buf, fp, sizeof buf);
228         if (rc < 0)
229                 goto err;
230
231         booldatum->value = le32_to_cpu(buf[0]);
232         booldatum->state = le32_to_cpu(buf[1]);
233
234         if (!bool_isvalid(booldatum))
235                 goto err;
236
237         len = le32_to_cpu(buf[2]);
238
239         key = kmalloc(len + 1, GFP_KERNEL);
240         if (!key)
241                 goto err;
242         rc = next_entry(key, fp, len);
243         if (rc < 0)
244                 goto err;
245         key[len] = 0;
246         if (hashtab_insert(h, key, booldatum))
247                 goto err;
248
249         return 0;
250 err:
251         cond_destroy_bool(key, booldatum, NULL);
252         return -1;
253 }
254
255 static int cond_read_av_list(struct policydb *p, void *fp, struct cond_av_list **ret_list,
256                              struct cond_av_list *other)
257 {
258         struct cond_av_list *list, *last = NULL, *cur;
259         struct avtab_key key;
260         struct avtab_datum datum;
261         struct avtab_node *node_ptr;
262         int rc;
263         u32 buf[1], i, len;
264         u8 found;
265
266         *ret_list = NULL;
267
268         len = 0;
269         rc = next_entry(buf, fp, sizeof buf);
270         if (rc < 0)
271                 return -1;
272
273         len = le32_to_cpu(buf[0]);
274         if (len == 0) {
275                 return 0;
276         }
277
278         for (i = 0; i < len; i++) {
279                 if (avtab_read_item(fp, &datum, &key))
280                         goto err;
281
282                 /*
283                  * For type rules we have to make certain there aren't any
284                  * conflicting rules by searching the te_avtab and the
285                  * cond_te_avtab.
286                  */
287                 if (datum.specified & AVTAB_TYPE) {
288                         if (avtab_search(&p->te_avtab, &key, AVTAB_TYPE)) {
289                                 printk("security: type rule already exists outside of a conditional.");
290                                 goto err;
291                         }
292                         /*
293                          * If we are reading the false list other will be a pointer to
294                          * the true list. We can have duplicate entries if there is only
295                          * 1 other entry and it is in our true list.
296                          *
297                          * If we are reading the true list (other == NULL) there shouldn't
298                          * be any other entries.
299                          */
300                         if (other) {
301                                 node_ptr = avtab_search_node(&p->te_cond_avtab, &key, AVTAB_TYPE);
302                                 if (node_ptr) {
303                                         if (avtab_search_node_next(node_ptr, AVTAB_TYPE)) {
304                                                 printk("security: too many conflicting type rules.");
305                                                 goto err;
306                                         }
307                                         found = 0;
308                                         for (cur = other; cur != NULL; cur = cur->next) {
309                                                 if (cur->node == node_ptr) {
310                                                         found = 1;
311                                                         break;
312                                                 }
313                                         }
314                                         if (!found) {
315                                                 printk("security: conflicting type rules.");
316                                                 goto err;
317                                         }
318                                 }
319                         } else {
320                                 if (avtab_search(&p->te_cond_avtab, &key, AVTAB_TYPE)) {
321                                         printk("security: conflicting type rules when adding type rule for true.");
322                                         goto err;
323                                 }
324                         }
325                 }
326                 node_ptr = avtab_insert_nonunique(&p->te_cond_avtab, &key, &datum);
327                 if (!node_ptr) {
328                         printk("security: could not insert rule.");
329                         goto err;
330                 }
331
332                 list = kmalloc(sizeof(struct cond_av_list), GFP_KERNEL);
333                 if (!list)
334                         goto err;
335                 memset(list, 0, sizeof(struct cond_av_list));
336
337                 list->node = node_ptr;
338                 if (i == 0)
339                         *ret_list = list;
340                 else
341                         last->next = list;
342                 last = list;
343
344         }
345
346         return 0;
347 err:
348         cond_av_list_destroy(*ret_list);
349         *ret_list = NULL;
350         return -1;
351 }
352
353 static int expr_isvalid(struct policydb *p, struct cond_expr *expr)
354 {
355         if (expr->expr_type <= 0 || expr->expr_type > COND_LAST) {
356                 printk("security: conditional expressions uses unknown operator.\n");
357                 return 0;
358         }
359
360         if (expr->bool > p->p_bools.nprim) {
361                 printk("security: conditional expressions uses unknown bool.\n");
362                 return 0;
363         }
364         return 1;
365 }
366
367 static int cond_read_node(struct policydb *p, struct cond_node *node, void *fp)
368 {
369         u32 buf[2], len, i;
370         int rc;
371         struct cond_expr *expr = NULL, *last = NULL;
372
373         rc = next_entry(buf, fp, sizeof(u32));
374         if (rc < 0)
375                 return -1;
376
377         node->cur_state = le32_to_cpu(buf[0]);
378
379         len = 0;
380         rc = next_entry(buf, fp, sizeof(u32));
381         if (rc < 0)
382                 return -1;
383
384         /* expr */
385         len = le32_to_cpu(buf[0]);
386
387         for (i = 0; i < len; i++ ) {
388                 rc = next_entry(buf, fp, sizeof(u32) * 2);
389                 if (rc < 0)
390                         goto err;
391
392                 expr = kmalloc(sizeof(struct cond_expr), GFP_KERNEL);
393                 if (!expr) {
394                         goto err;
395                 }
396                 memset(expr, 0, sizeof(struct cond_expr));
397
398                 expr->expr_type = le32_to_cpu(buf[0]);
399                 expr->bool = le32_to_cpu(buf[1]);
400
401                 if (!expr_isvalid(p, expr)) {
402                         kfree(expr);
403                         goto err;
404                 }
405
406                 if (i == 0) {
407                         node->expr = expr;
408                 } else {
409                         last->next = expr;
410                 }
411                 last = expr;
412         }
413
414         if (cond_read_av_list(p, fp, &node->true_list, NULL) != 0)
415                 goto err;
416         if (cond_read_av_list(p, fp, &node->false_list, node->true_list) != 0)
417                 goto err;
418         return 0;
419 err:
420         cond_node_destroy(node);
421         return -1;
422 }
423
424 int cond_read_list(struct policydb *p, void *fp)
425 {
426         struct cond_node *node, *last = NULL;
427         u32 buf[1], i, len;
428         int rc;
429
430         rc = next_entry(buf, fp, sizeof buf);
431         if (rc < 0)
432                 return -1;
433
434         len = le32_to_cpu(buf[0]);
435
436         for (i = 0; i < len; i++) {
437                 node = kmalloc(sizeof(struct cond_node), GFP_KERNEL);
438                 if (!node)
439                         goto err;
440                 memset(node, 0, sizeof(struct cond_node));
441
442                 if (cond_read_node(p, node, fp) != 0)
443                         goto err;
444
445                 if (i == 0) {
446                         p->cond_list = node;
447                 } else {
448                         last->next = node;
449                 }
450                 last = node;
451         }
452         return 0;
453 err:
454         cond_list_destroy(p->cond_list);
455         return -1;
456 }
457
458 /* Determine whether additional permissions are granted by the conditional
459  * av table, and if so, add them to the result
460  */
461 void cond_compute_av(struct avtab *ctab, struct avtab_key *key, struct av_decision *avd)
462 {
463         struct avtab_node *node;
464
465         if(!ctab || !key || !avd)
466                 return;
467
468         for(node = avtab_search_node(ctab, key, AVTAB_AV); node != NULL;
469                                 node = avtab_search_node_next(node, AVTAB_AV)) {
470                 if ( (__u32) (AVTAB_ALLOWED|AVTAB_ENABLED) ==
471                      (node->datum.specified & (AVTAB_ALLOWED|AVTAB_ENABLED)))
472                         avd->allowed |= avtab_allowed(&node->datum);
473                 if ( (__u32) (AVTAB_AUDITDENY|AVTAB_ENABLED) ==
474                      (node->datum.specified & (AVTAB_AUDITDENY|AVTAB_ENABLED)))
475                         /* Since a '0' in an auditdeny mask represents a
476                          * permission we do NOT want to audit (dontaudit), we use
477                          * the '&' operand to ensure that all '0's in the mask
478                          * are retained (much unlike the allow and auditallow cases).
479                          */
480                         avd->auditdeny &= avtab_auditdeny(&node->datum);
481                 if ( (__u32) (AVTAB_AUDITALLOW|AVTAB_ENABLED) ==
482                      (node->datum.specified & (AVTAB_AUDITALLOW|AVTAB_ENABLED)))
483                         avd->auditallow |= avtab_auditallow(&node->datum);
484         }
485         return;
486 }