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1/*
2 * Copyright (C) 2008 IBM Corporation
3 * Author: Mimi Zohar <zohar@us.ibm.com>
4 *
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 of the License.
8 *
9 * ima_policy.c
10 * - initialize default measure policy rules
11 *
12 */
13#include <linux/module.h>
14#include <linux/list.h>
15#include <linux/security.h>
16#include <linux/magic.h>
17#include <linux/parser.h>
18#include <linux/slab.h>
19
20#include "ima.h"
21
22/* flags definitions */
23#define IMA_FUNC 0x0001
24#define IMA_MASK 0x0002
25#define IMA_FSMAGIC 0x0004
26#define IMA_UID 0x0008
27
28enum ima_action { UNKNOWN = -1, DONT_MEASURE = 0, MEASURE };
29
30#define MAX_LSM_RULES 6
31enum lsm_rule_types { LSM_OBJ_USER, LSM_OBJ_ROLE, LSM_OBJ_TYPE,
32 LSM_SUBJ_USER, LSM_SUBJ_ROLE, LSM_SUBJ_TYPE
33};
34
35struct ima_measure_rule_entry {
36 struct list_head list;
37 enum ima_action action;
38 unsigned int flags;
39 enum ima_hooks func;
40 int mask;
41 unsigned long fsmagic;
42 uid_t uid;
43 struct {
44 void *rule; /* LSM file metadata specific */
45 int type; /* audit type */
46 } lsm[MAX_LSM_RULES];
47};
48
49/*
50 * Without LSM specific knowledge, the default policy can only be
51 * written in terms of .action, .func, .mask, .fsmagic, and .uid
52 */
53
54/*
55 * The minimum rule set to allow for full TCB coverage. Measures all files
56 * opened or mmap for exec and everything read by root. Dangerous because
57 * normal users can easily run the machine out of memory simply building
58 * and running executables.
59 */
60static struct ima_measure_rule_entry default_rules[] = {
61 {.action = DONT_MEASURE,.fsmagic = PROC_SUPER_MAGIC,.flags = IMA_FSMAGIC},
62 {.action = DONT_MEASURE,.fsmagic = SYSFS_MAGIC,.flags = IMA_FSMAGIC},
63 {.action = DONT_MEASURE,.fsmagic = DEBUGFS_MAGIC,.flags = IMA_FSMAGIC},
64 {.action = DONT_MEASURE,.fsmagic = TMPFS_MAGIC,.flags = IMA_FSMAGIC},
65 {.action = DONT_MEASURE,.fsmagic = RAMFS_MAGIC,.flags = IMA_FSMAGIC},
66 {.action = DONT_MEASURE,.fsmagic = SECURITYFS_MAGIC,.flags = IMA_FSMAGIC},
67 {.action = DONT_MEASURE,.fsmagic = SELINUX_MAGIC,.flags = IMA_FSMAGIC},
68 {.action = MEASURE,.func = FILE_MMAP,.mask = MAY_EXEC,
69 .flags = IMA_FUNC | IMA_MASK},
70 {.action = MEASURE,.func = BPRM_CHECK,.mask = MAY_EXEC,
71 .flags = IMA_FUNC | IMA_MASK},
72 {.action = MEASURE,.func = FILE_CHECK,.mask = MAY_READ,.uid = 0,
73 .flags = IMA_FUNC | IMA_MASK | IMA_UID},
74};
75
76static LIST_HEAD(measure_default_rules);
77static LIST_HEAD(measure_policy_rules);
78static struct list_head *ima_measure;
79
80static DEFINE_MUTEX(ima_measure_mutex);
81
82static bool ima_use_tcb __initdata;
83static int __init default_policy_setup(char *str)
84{
85 ima_use_tcb = 1;
86 return 1;
87}
88__setup("ima_tcb", default_policy_setup);
89
90/**
91 * ima_match_rules - determine whether an inode matches the measure rule.
92 * @rule: a pointer to a rule
93 * @inode: a pointer to an inode
94 * @func: LIM hook identifier
95 * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC)
96 *
97 * Returns true on rule match, false on failure.
98 */
99static bool ima_match_rules(struct ima_measure_rule_entry *rule,
100 struct inode *inode, enum ima_hooks func, int mask)
101{
102 struct task_struct *tsk = current;
103 const struct cred *cred = current_cred();
104 int i;
105
106 if ((rule->flags & IMA_FUNC) && rule->func != func)
107 return false;
108 if ((rule->flags & IMA_MASK) && rule->mask != mask)
109 return false;
110 if ((rule->flags & IMA_FSMAGIC)
111 && rule->fsmagic != inode->i_sb->s_magic)
112 return false;
113 if ((rule->flags & IMA_UID) && rule->uid != cred->uid)
114 return false;
115 for (i = 0; i < MAX_LSM_RULES; i++) {
116 int rc = 0;
117 u32 osid, sid;
118
119 if (!rule->lsm[i].rule)
120 continue;
121
122 switch (i) {
123 case LSM_OBJ_USER:
124 case LSM_OBJ_ROLE:
125 case LSM_OBJ_TYPE:
126 security_inode_getsecid(inode, &osid);
127 rc = security_filter_rule_match(osid,
128 rule->lsm[i].type,
129 Audit_equal,
130 rule->lsm[i].rule,
131 NULL);
132 break;
133 case LSM_SUBJ_USER:
134 case LSM_SUBJ_ROLE:
135 case LSM_SUBJ_TYPE:
136 security_task_getsecid(tsk, &sid);
137 rc = security_filter_rule_match(sid,
138 rule->lsm[i].type,
139 Audit_equal,
140 rule->lsm[i].rule,
141 NULL);
142 default:
143 break;
144 }
145 if (!rc)
146 return false;
147 }
148 return true;
149}
150
151/**
152 * ima_match_policy - decision based on LSM and other conditions
153 * @inode: pointer to an inode for which the policy decision is being made
154 * @func: IMA hook identifier
155 * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC)
156 *
157 * Measure decision based on func/mask/fsmagic and LSM(subj/obj/type)
158 * conditions.
159 *
160 * (There is no need for locking when walking the policy list,
161 * as elements in the list are never deleted, nor does the list
162 * change.)
163 */
164int ima_match_policy(struct inode *inode, enum ima_hooks func, int mask)
165{
166 struct ima_measure_rule_entry *entry;
167
168 list_for_each_entry(entry, ima_measure, list) {
169 bool rc;
170
171 rc = ima_match_rules(entry, inode, func, mask);
172 if (rc)
173 return entry->action;
174 }
175 return 0;
176}
177
178/**
179 * ima_init_policy - initialize the default measure rules.
180 *
181 * ima_measure points to either the measure_default_rules or the
182 * the new measure_policy_rules.
183 */
184void __init ima_init_policy(void)
185{
186 int i, entries;
187
188 /* if !ima_use_tcb set entries = 0 so we load NO default rules */
189 if (ima_use_tcb)
190 entries = ARRAY_SIZE(default_rules);
191 else
192 entries = 0;
193
194 for (i = 0; i < entries; i++)
195 list_add_tail(&default_rules[i].list, &measure_default_rules);
196 ima_measure = &measure_default_rules;
197}
198
199/**
200 * ima_update_policy - update default_rules with new measure rules
201 *
202 * Called on file .release to update the default rules with a complete new
203 * policy. Once updated, the policy is locked, no additional rules can be
204 * added to the policy.
205 */
206void ima_update_policy(void)
207{
208 const char *op = "policy_update";
209 const char *cause = "already exists";
210 int result = 1;
211 int audit_info = 0;
212
213 if (ima_measure == &measure_default_rules) {
214 ima_measure = &measure_policy_rules;
215 cause = "complete";
216 result = 0;
217 }
218 integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
219 NULL, op, cause, result, audit_info);
220}
221
222enum {
223 Opt_err = -1,
224 Opt_measure = 1, Opt_dont_measure,
225 Opt_obj_user, Opt_obj_role, Opt_obj_type,
226 Opt_subj_user, Opt_subj_role, Opt_subj_type,
227 Opt_func, Opt_mask, Opt_fsmagic, Opt_uid
228};
229
230static match_table_t policy_tokens = {
231 {Opt_measure, "measure"},
232 {Opt_dont_measure, "dont_measure"},
233 {Opt_obj_user, "obj_user=%s"},
234 {Opt_obj_role, "obj_role=%s"},
235 {Opt_obj_type, "obj_type=%s"},
236 {Opt_subj_user, "subj_user=%s"},
237 {Opt_subj_role, "subj_role=%s"},
238 {Opt_subj_type, "subj_type=%s"},
239 {Opt_func, "func=%s"},
240 {Opt_mask, "mask=%s"},
241 {Opt_fsmagic, "fsmagic=%s"},
242 {Opt_uid, "uid=%s"},
243 {Opt_err, NULL}
244};
245
246static int ima_lsm_rule_init(struct ima_measure_rule_entry *entry,
247 char *args, int lsm_rule, int audit_type)
248{
249 int result;
250
251 if (entry->lsm[lsm_rule].rule)
252 return -EINVAL;
253
254 entry->lsm[lsm_rule].type = audit_type;
255 result = security_filter_rule_init(entry->lsm[lsm_rule].type,
256 Audit_equal, args,
257 &entry->lsm[lsm_rule].rule);
258 if (!entry->lsm[lsm_rule].rule)
259 return -EINVAL;
260 return result;
261}
262
263static void ima_log_string(struct audit_buffer *ab, char *key, char *value)
264{
265 audit_log_format(ab, "%s=", key);
266 audit_log_untrustedstring(ab, value);
267 audit_log_format(ab, " ");
268}
269
270static int ima_parse_rule(char *rule, struct ima_measure_rule_entry *entry)
271{
272 struct audit_buffer *ab;
273 char *p;
274 int result = 0;
275
276 ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_INTEGRITY_RULE);
277
278 entry->uid = -1;
279 entry->action = UNKNOWN;
280 while ((p = strsep(&rule, " \t")) != NULL) {
281 substring_t args[MAX_OPT_ARGS];
282 int token;
283 unsigned long lnum;
284
285 if (result < 0)
286 break;
287 if ((*p == '\0') || (*p == ' ') || (*p == '\t'))
288 continue;
289 token = match_token(p, policy_tokens, args);
290 switch (token) {
291 case Opt_measure:
292 ima_log_string(ab, "action", "measure");
293
294 if (entry->action != UNKNOWN)
295 result = -EINVAL;
296
297 entry->action = MEASURE;
298 break;
299 case Opt_dont_measure:
300 ima_log_string(ab, "action", "dont_measure");
301
302 if (entry->action != UNKNOWN)
303 result = -EINVAL;
304
305 entry->action = DONT_MEASURE;
306 break;
307 case Opt_func:
308 ima_log_string(ab, "func", args[0].from);
309
310 if (entry->func)
311 result = -EINVAL;
312
313 if (strcmp(args[0].from, "FILE_CHECK") == 0)
314 entry->func = FILE_CHECK;
315 /* PATH_CHECK is for backwards compat */
316 else if (strcmp(args[0].from, "PATH_CHECK") == 0)
317 entry->func = FILE_CHECK;
318 else if (strcmp(args[0].from, "FILE_MMAP") == 0)
319 entry->func = FILE_MMAP;
320 else if (strcmp(args[0].from, "BPRM_CHECK") == 0)
321 entry->func = BPRM_CHECK;
322 else
323 result = -EINVAL;
324 if (!result)
325 entry->flags |= IMA_FUNC;
326 break;
327 case Opt_mask:
328 ima_log_string(ab, "mask", args[0].from);
329
330 if (entry->mask)
331 result = -EINVAL;
332
333 if ((strcmp(args[0].from, "MAY_EXEC")) == 0)
334 entry->mask = MAY_EXEC;
335 else if (strcmp(args[0].from, "MAY_WRITE") == 0)
336 entry->mask = MAY_WRITE;
337 else if (strcmp(args[0].from, "MAY_READ") == 0)
338 entry->mask = MAY_READ;
339 else if (strcmp(args[0].from, "MAY_APPEND") == 0)
340 entry->mask = MAY_APPEND;
341 else
342 result = -EINVAL;
343 if (!result)
344 entry->flags |= IMA_MASK;
345 break;
346 case Opt_fsmagic:
347 ima_log_string(ab, "fsmagic", args[0].from);
348
349 if (entry->fsmagic) {
350 result = -EINVAL;
351 break;
352 }
353
354 result = strict_strtoul(args[0].from, 16,
355 &entry->fsmagic);
356 if (!result)
357 entry->flags |= IMA_FSMAGIC;
358 break;
359 case Opt_uid:
360 ima_log_string(ab, "uid", args[0].from);
361
362 if (entry->uid != -1) {
363 result = -EINVAL;
364 break;
365 }
366
367 result = strict_strtoul(args[0].from, 10, &lnum);
368 if (!result) {
369 entry->uid = (uid_t) lnum;
370 if (entry->uid != lnum)
371 result = -EINVAL;
372 else
373 entry->flags |= IMA_UID;
374 }
375 break;
376 case Opt_obj_user:
377 ima_log_string(ab, "obj_user", args[0].from);
378 result = ima_lsm_rule_init(entry, args[0].from,
379 LSM_OBJ_USER,
380 AUDIT_OBJ_USER);
381 break;
382 case Opt_obj_role:
383 ima_log_string(ab, "obj_role", args[0].from);
384 result = ima_lsm_rule_init(entry, args[0].from,
385 LSM_OBJ_ROLE,
386 AUDIT_OBJ_ROLE);
387 break;
388 case Opt_obj_type:
389 ima_log_string(ab, "obj_type", args[0].from);
390 result = ima_lsm_rule_init(entry, args[0].from,
391 LSM_OBJ_TYPE,
392 AUDIT_OBJ_TYPE);
393 break;
394 case Opt_subj_user:
395 ima_log_string(ab, "subj_user", args[0].from);
396 result = ima_lsm_rule_init(entry, args[0].from,
397 LSM_SUBJ_USER,
398 AUDIT_SUBJ_USER);
399 break;
400 case Opt_subj_role:
401 ima_log_string(ab, "subj_role", args[0].from);
402 result = ima_lsm_rule_init(entry, args[0].from,
403 LSM_SUBJ_ROLE,
404 AUDIT_SUBJ_ROLE);
405 break;
406 case Opt_subj_type:
407 ima_log_string(ab, "subj_type", args[0].from);
408 result = ima_lsm_rule_init(entry, args[0].from,
409 LSM_SUBJ_TYPE,
410 AUDIT_SUBJ_TYPE);
411 break;
412 case Opt_err:
413 ima_log_string(ab, "UNKNOWN", p);
414 result = -EINVAL;
415 break;
416 }
417 }
418 if (!result && (entry->action == UNKNOWN))
419 result = -EINVAL;
420
421 audit_log_format(ab, "res=%d", !result);
422 audit_log_end(ab);
423 return result;
424}
425
426/**
427 * ima_parse_add_rule - add a rule to measure_policy_rules
428 * @rule - ima measurement policy rule
429 *
430 * Uses a mutex to protect the policy list from multiple concurrent writers.
431 * Returns the length of the rule parsed, an error code on failure
432 */
433ssize_t ima_parse_add_rule(char *rule)
434{
435 const char *op = "update_policy";
436 char *p;
437 struct ima_measure_rule_entry *entry;
438 ssize_t result, len;
439 int audit_info = 0;
440
441 /* Prevent installed policy from changing */
442 if (ima_measure != &measure_default_rules) {
443 integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
444 NULL, op, "already exists",
445 -EACCES, audit_info);
446 return -EACCES;
447 }
448
449 entry = kzalloc(sizeof(*entry), GFP_KERNEL);
450 if (!entry) {
451 integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
452 NULL, op, "-ENOMEM", -ENOMEM, audit_info);
453 return -ENOMEM;
454 }
455
456 INIT_LIST_HEAD(&entry->list);
457
458 p = strsep(&rule, "\n");
459 len = strlen(p) + 1;
460
461 if (*p == '#') {
462 kfree(entry);
463 return len;
464 }
465
466 result = ima_parse_rule(p, entry);
467 if (result) {
468 kfree(entry);
469 integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
470 NULL, op, "invalid policy", result,
471 audit_info);
472 return result;
473 }
474
475 mutex_lock(&ima_measure_mutex);
476 list_add_tail(&entry->list, &measure_policy_rules);
477 mutex_unlock(&ima_measure_mutex);
478
479 return len;
480}
481
482/* ima_delete_rules called to cleanup invalid policy */
483void ima_delete_rules(void)
484{
485 struct ima_measure_rule_entry *entry, *tmp;
486
487 mutex_lock(&ima_measure_mutex);
488 list_for_each_entry_safe(entry, tmp, &measure_policy_rules, list) {
489 list_del(&entry->list);
490 kfree(entry);
491 }
492 mutex_unlock(&ima_measure_mutex);
493}
1/*
2 * Copyright (C) 2008 IBM Corporation
3 * Author: Mimi Zohar <zohar@us.ibm.com>
4 *
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 of the License.
8 *
9 * ima_policy.c
10 * - initialize default measure policy rules
11 *
12 */
13#include <linux/module.h>
14#include <linux/list.h>
15#include <linux/security.h>
16#include <linux/magic.h>
17#include <linux/parser.h>
18#include <linux/slab.h>
19#include <linux/genhd.h>
20
21#include "ima.h"
22
23/* flags definitions */
24#define IMA_FUNC 0x0001
25#define IMA_MASK 0x0002
26#define IMA_FSMAGIC 0x0004
27#define IMA_UID 0x0008
28#define IMA_FOWNER 0x0010
29#define IMA_FSUUID 0x0020
30
31#define UNKNOWN 0
32#define MEASURE 0x0001 /* same as IMA_MEASURE */
33#define DONT_MEASURE 0x0002
34#define APPRAISE 0x0004 /* same as IMA_APPRAISE */
35#define DONT_APPRAISE 0x0008
36#define AUDIT 0x0040
37
38#define MAX_LSM_RULES 6
39enum lsm_rule_types { LSM_OBJ_USER, LSM_OBJ_ROLE, LSM_OBJ_TYPE,
40 LSM_SUBJ_USER, LSM_SUBJ_ROLE, LSM_SUBJ_TYPE
41};
42
43struct ima_rule_entry {
44 struct list_head list;
45 int action;
46 unsigned int flags;
47 enum ima_hooks func;
48 int mask;
49 unsigned long fsmagic;
50 u8 fsuuid[16];
51 kuid_t uid;
52 kuid_t fowner;
53 struct {
54 void *rule; /* LSM file metadata specific */
55 void *args_p; /* audit value */
56 int type; /* audit type */
57 } lsm[MAX_LSM_RULES];
58};
59
60/*
61 * Without LSM specific knowledge, the default policy can only be
62 * written in terms of .action, .func, .mask, .fsmagic, .uid, and .fowner
63 */
64
65/*
66 * The minimum rule set to allow for full TCB coverage. Measures all files
67 * opened or mmap for exec and everything read by root. Dangerous because
68 * normal users can easily run the machine out of memory simply building
69 * and running executables.
70 */
71static struct ima_rule_entry default_rules[] = {
72 {.action = DONT_MEASURE, .fsmagic = PROC_SUPER_MAGIC, .flags = IMA_FSMAGIC},
73 {.action = DONT_MEASURE, .fsmagic = SYSFS_MAGIC, .flags = IMA_FSMAGIC},
74 {.action = DONT_MEASURE, .fsmagic = DEBUGFS_MAGIC, .flags = IMA_FSMAGIC},
75 {.action = DONT_MEASURE, .fsmagic = TMPFS_MAGIC, .flags = IMA_FSMAGIC},
76 {.action = DONT_MEASURE, .fsmagic = DEVPTS_SUPER_MAGIC, .flags = IMA_FSMAGIC},
77 {.action = DONT_MEASURE, .fsmagic = BINFMTFS_MAGIC, .flags = IMA_FSMAGIC},
78 {.action = DONT_MEASURE, .fsmagic = SECURITYFS_MAGIC, .flags = IMA_FSMAGIC},
79 {.action = DONT_MEASURE, .fsmagic = SELINUX_MAGIC, .flags = IMA_FSMAGIC},
80 {.action = MEASURE, .func = MMAP_CHECK, .mask = MAY_EXEC,
81 .flags = IMA_FUNC | IMA_MASK},
82 {.action = MEASURE, .func = BPRM_CHECK, .mask = MAY_EXEC,
83 .flags = IMA_FUNC | IMA_MASK},
84 {.action = MEASURE, .func = FILE_CHECK, .mask = MAY_READ, .uid = GLOBAL_ROOT_UID,
85 .flags = IMA_FUNC | IMA_MASK | IMA_UID},
86 {.action = MEASURE, .func = MODULE_CHECK, .flags = IMA_FUNC},
87};
88
89static struct ima_rule_entry default_appraise_rules[] = {
90 {.action = DONT_APPRAISE, .fsmagic = PROC_SUPER_MAGIC, .flags = IMA_FSMAGIC},
91 {.action = DONT_APPRAISE, .fsmagic = SYSFS_MAGIC, .flags = IMA_FSMAGIC},
92 {.action = DONT_APPRAISE, .fsmagic = DEBUGFS_MAGIC, .flags = IMA_FSMAGIC},
93 {.action = DONT_APPRAISE, .fsmagic = TMPFS_MAGIC, .flags = IMA_FSMAGIC},
94 {.action = DONT_APPRAISE, .fsmagic = RAMFS_MAGIC, .flags = IMA_FSMAGIC},
95 {.action = DONT_APPRAISE, .fsmagic = DEVPTS_SUPER_MAGIC, .flags = IMA_FSMAGIC},
96 {.action = DONT_APPRAISE, .fsmagic = BINFMTFS_MAGIC, .flags = IMA_FSMAGIC},
97 {.action = DONT_APPRAISE, .fsmagic = SECURITYFS_MAGIC, .flags = IMA_FSMAGIC},
98 {.action = DONT_APPRAISE, .fsmagic = SELINUX_MAGIC, .flags = IMA_FSMAGIC},
99 {.action = DONT_APPRAISE, .fsmagic = CGROUP_SUPER_MAGIC, .flags = IMA_FSMAGIC},
100 {.action = APPRAISE, .fowner = GLOBAL_ROOT_UID, .flags = IMA_FOWNER},
101};
102
103static LIST_HEAD(ima_default_rules);
104static LIST_HEAD(ima_policy_rules);
105static struct list_head *ima_rules;
106
107static DEFINE_MUTEX(ima_rules_mutex);
108
109static bool ima_use_tcb __initdata;
110static int __init default_measure_policy_setup(char *str)
111{
112 ima_use_tcb = 1;
113 return 1;
114}
115__setup("ima_tcb", default_measure_policy_setup);
116
117static bool ima_use_appraise_tcb __initdata;
118static int __init default_appraise_policy_setup(char *str)
119{
120 ima_use_appraise_tcb = 1;
121 return 1;
122}
123__setup("ima_appraise_tcb", default_appraise_policy_setup);
124
125/*
126 * Although the IMA policy does not change, the LSM policy can be
127 * reloaded, leaving the IMA LSM based rules referring to the old,
128 * stale LSM policy.
129 *
130 * Update the IMA LSM based rules to reflect the reloaded LSM policy.
131 * We assume the rules still exist; and BUG_ON() if they don't.
132 */
133static void ima_lsm_update_rules(void)
134{
135 struct ima_rule_entry *entry, *tmp;
136 int result;
137 int i;
138
139 mutex_lock(&ima_rules_mutex);
140 list_for_each_entry_safe(entry, tmp, &ima_policy_rules, list) {
141 for (i = 0; i < MAX_LSM_RULES; i++) {
142 if (!entry->lsm[i].rule)
143 continue;
144 result = security_filter_rule_init(entry->lsm[i].type,
145 Audit_equal,
146 entry->lsm[i].args_p,
147 &entry->lsm[i].rule);
148 BUG_ON(!entry->lsm[i].rule);
149 }
150 }
151 mutex_unlock(&ima_rules_mutex);
152}
153
154/**
155 * ima_match_rules - determine whether an inode matches the measure rule.
156 * @rule: a pointer to a rule
157 * @inode: a pointer to an inode
158 * @func: LIM hook identifier
159 * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC)
160 *
161 * Returns true on rule match, false on failure.
162 */
163static bool ima_match_rules(struct ima_rule_entry *rule,
164 struct inode *inode, enum ima_hooks func, int mask)
165{
166 struct task_struct *tsk = current;
167 const struct cred *cred = current_cred();
168 int i;
169
170 if ((rule->flags & IMA_FUNC) &&
171 (rule->func != func && func != POST_SETATTR))
172 return false;
173 if ((rule->flags & IMA_MASK) &&
174 (rule->mask != mask && func != POST_SETATTR))
175 return false;
176 if ((rule->flags & IMA_FSMAGIC)
177 && rule->fsmagic != inode->i_sb->s_magic)
178 return false;
179 if ((rule->flags & IMA_FSUUID) &&
180 memcmp(rule->fsuuid, inode->i_sb->s_uuid, sizeof(rule->fsuuid)))
181 return false;
182 if ((rule->flags & IMA_UID) && !uid_eq(rule->uid, cred->uid))
183 return false;
184 if ((rule->flags & IMA_FOWNER) && !uid_eq(rule->fowner, inode->i_uid))
185 return false;
186 for (i = 0; i < MAX_LSM_RULES; i++) {
187 int rc = 0;
188 u32 osid, sid;
189 int retried = 0;
190
191 if (!rule->lsm[i].rule)
192 continue;
193retry:
194 switch (i) {
195 case LSM_OBJ_USER:
196 case LSM_OBJ_ROLE:
197 case LSM_OBJ_TYPE:
198 security_inode_getsecid(inode, &osid);
199 rc = security_filter_rule_match(osid,
200 rule->lsm[i].type,
201 Audit_equal,
202 rule->lsm[i].rule,
203 NULL);
204 break;
205 case LSM_SUBJ_USER:
206 case LSM_SUBJ_ROLE:
207 case LSM_SUBJ_TYPE:
208 security_task_getsecid(tsk, &sid);
209 rc = security_filter_rule_match(sid,
210 rule->lsm[i].type,
211 Audit_equal,
212 rule->lsm[i].rule,
213 NULL);
214 default:
215 break;
216 }
217 if ((rc < 0) && (!retried)) {
218 retried = 1;
219 ima_lsm_update_rules();
220 goto retry;
221 }
222 if (!rc)
223 return false;
224 }
225 return true;
226}
227
228/*
229 * In addition to knowing that we need to appraise the file in general,
230 * we need to differentiate between calling hooks, for hook specific rules.
231 */
232static int get_subaction(struct ima_rule_entry *rule, int func)
233{
234 if (!(rule->flags & IMA_FUNC))
235 return IMA_FILE_APPRAISE;
236
237 switch (func) {
238 case MMAP_CHECK:
239 return IMA_MMAP_APPRAISE;
240 case BPRM_CHECK:
241 return IMA_BPRM_APPRAISE;
242 case MODULE_CHECK:
243 return IMA_MODULE_APPRAISE;
244 case FILE_CHECK:
245 default:
246 return IMA_FILE_APPRAISE;
247 }
248}
249
250/**
251 * ima_match_policy - decision based on LSM and other conditions
252 * @inode: pointer to an inode for which the policy decision is being made
253 * @func: IMA hook identifier
254 * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC)
255 *
256 * Measure decision based on func/mask/fsmagic and LSM(subj/obj/type)
257 * conditions.
258 *
259 * (There is no need for locking when walking the policy list,
260 * as elements in the list are never deleted, nor does the list
261 * change.)
262 */
263int ima_match_policy(struct inode *inode, enum ima_hooks func, int mask,
264 int flags)
265{
266 struct ima_rule_entry *entry;
267 int action = 0, actmask = flags | (flags << 1);
268
269 list_for_each_entry(entry, ima_rules, list) {
270
271 if (!(entry->action & actmask))
272 continue;
273
274 if (!ima_match_rules(entry, inode, func, mask))
275 continue;
276
277 action |= entry->flags & IMA_ACTION_FLAGS;
278
279 action |= entry->action & IMA_DO_MASK;
280 if (entry->action & IMA_APPRAISE)
281 action |= get_subaction(entry, func);
282
283 if (entry->action & IMA_DO_MASK)
284 actmask &= ~(entry->action | entry->action << 1);
285 else
286 actmask &= ~(entry->action | entry->action >> 1);
287
288 if (!actmask)
289 break;
290 }
291
292 return action;
293}
294
295/**
296 * ima_init_policy - initialize the default measure rules.
297 *
298 * ima_rules points to either the ima_default_rules or the
299 * the new ima_policy_rules.
300 */
301void __init ima_init_policy(void)
302{
303 int i, measure_entries, appraise_entries;
304
305 /* if !ima_use_tcb set entries = 0 so we load NO default rules */
306 measure_entries = ima_use_tcb ? ARRAY_SIZE(default_rules) : 0;
307 appraise_entries = ima_use_appraise_tcb ?
308 ARRAY_SIZE(default_appraise_rules) : 0;
309
310 for (i = 0; i < measure_entries + appraise_entries; i++) {
311 if (i < measure_entries)
312 list_add_tail(&default_rules[i].list,
313 &ima_default_rules);
314 else {
315 int j = i - measure_entries;
316
317 list_add_tail(&default_appraise_rules[j].list,
318 &ima_default_rules);
319 }
320 }
321
322 ima_rules = &ima_default_rules;
323}
324
325/**
326 * ima_update_policy - update default_rules with new measure rules
327 *
328 * Called on file .release to update the default rules with a complete new
329 * policy. Once updated, the policy is locked, no additional rules can be
330 * added to the policy.
331 */
332void ima_update_policy(void)
333{
334 static const char op[] = "policy_update";
335 const char *cause = "already exists";
336 int result = 1;
337 int audit_info = 0;
338
339 if (ima_rules == &ima_default_rules) {
340 ima_rules = &ima_policy_rules;
341 cause = "complete";
342 result = 0;
343 }
344 integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
345 NULL, op, cause, result, audit_info);
346}
347
348enum {
349 Opt_err = -1,
350 Opt_measure = 1, Opt_dont_measure,
351 Opt_appraise, Opt_dont_appraise,
352 Opt_audit,
353 Opt_obj_user, Opt_obj_role, Opt_obj_type,
354 Opt_subj_user, Opt_subj_role, Opt_subj_type,
355 Opt_func, Opt_mask, Opt_fsmagic, Opt_uid, Opt_fowner,
356 Opt_appraise_type, Opt_fsuuid
357};
358
359static match_table_t policy_tokens = {
360 {Opt_measure, "measure"},
361 {Opt_dont_measure, "dont_measure"},
362 {Opt_appraise, "appraise"},
363 {Opt_dont_appraise, "dont_appraise"},
364 {Opt_audit, "audit"},
365 {Opt_obj_user, "obj_user=%s"},
366 {Opt_obj_role, "obj_role=%s"},
367 {Opt_obj_type, "obj_type=%s"},
368 {Opt_subj_user, "subj_user=%s"},
369 {Opt_subj_role, "subj_role=%s"},
370 {Opt_subj_type, "subj_type=%s"},
371 {Opt_func, "func=%s"},
372 {Opt_mask, "mask=%s"},
373 {Opt_fsmagic, "fsmagic=%s"},
374 {Opt_fsuuid, "fsuuid=%s"},
375 {Opt_uid, "uid=%s"},
376 {Opt_fowner, "fowner=%s"},
377 {Opt_appraise_type, "appraise_type=%s"},
378 {Opt_err, NULL}
379};
380
381static int ima_lsm_rule_init(struct ima_rule_entry *entry,
382 substring_t *args, int lsm_rule, int audit_type)
383{
384 int result;
385
386 if (entry->lsm[lsm_rule].rule)
387 return -EINVAL;
388
389 entry->lsm[lsm_rule].args_p = match_strdup(args);
390 if (!entry->lsm[lsm_rule].args_p)
391 return -ENOMEM;
392
393 entry->lsm[lsm_rule].type = audit_type;
394 result = security_filter_rule_init(entry->lsm[lsm_rule].type,
395 Audit_equal,
396 entry->lsm[lsm_rule].args_p,
397 &entry->lsm[lsm_rule].rule);
398 if (!entry->lsm[lsm_rule].rule) {
399 kfree(entry->lsm[lsm_rule].args_p);
400 return -EINVAL;
401 }
402
403 return result;
404}
405
406static void ima_log_string(struct audit_buffer *ab, char *key, char *value)
407{
408 audit_log_format(ab, "%s=", key);
409 audit_log_untrustedstring(ab, value);
410 audit_log_format(ab, " ");
411}
412
413static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
414{
415 struct audit_buffer *ab;
416 char *p;
417 int result = 0;
418
419 ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_INTEGRITY_RULE);
420
421 entry->uid = INVALID_UID;
422 entry->fowner = INVALID_UID;
423 entry->action = UNKNOWN;
424 while ((p = strsep(&rule, " \t")) != NULL) {
425 substring_t args[MAX_OPT_ARGS];
426 int token;
427 unsigned long lnum;
428
429 if (result < 0)
430 break;
431 if ((*p == '\0') || (*p == ' ') || (*p == '\t'))
432 continue;
433 token = match_token(p, policy_tokens, args);
434 switch (token) {
435 case Opt_measure:
436 ima_log_string(ab, "action", "measure");
437
438 if (entry->action != UNKNOWN)
439 result = -EINVAL;
440
441 entry->action = MEASURE;
442 break;
443 case Opt_dont_measure:
444 ima_log_string(ab, "action", "dont_measure");
445
446 if (entry->action != UNKNOWN)
447 result = -EINVAL;
448
449 entry->action = DONT_MEASURE;
450 break;
451 case Opt_appraise:
452 ima_log_string(ab, "action", "appraise");
453
454 if (entry->action != UNKNOWN)
455 result = -EINVAL;
456
457 entry->action = APPRAISE;
458 break;
459 case Opt_dont_appraise:
460 ima_log_string(ab, "action", "dont_appraise");
461
462 if (entry->action != UNKNOWN)
463 result = -EINVAL;
464
465 entry->action = DONT_APPRAISE;
466 break;
467 case Opt_audit:
468 ima_log_string(ab, "action", "audit");
469
470 if (entry->action != UNKNOWN)
471 result = -EINVAL;
472
473 entry->action = AUDIT;
474 break;
475 case Opt_func:
476 ima_log_string(ab, "func", args[0].from);
477
478 if (entry->func)
479 result = -EINVAL;
480
481 if (strcmp(args[0].from, "FILE_CHECK") == 0)
482 entry->func = FILE_CHECK;
483 /* PATH_CHECK is for backwards compat */
484 else if (strcmp(args[0].from, "PATH_CHECK") == 0)
485 entry->func = FILE_CHECK;
486 else if (strcmp(args[0].from, "MODULE_CHECK") == 0)
487 entry->func = MODULE_CHECK;
488 else if ((strcmp(args[0].from, "FILE_MMAP") == 0)
489 || (strcmp(args[0].from, "MMAP_CHECK") == 0))
490 entry->func = MMAP_CHECK;
491 else if (strcmp(args[0].from, "BPRM_CHECK") == 0)
492 entry->func = BPRM_CHECK;
493 else
494 result = -EINVAL;
495 if (!result)
496 entry->flags |= IMA_FUNC;
497 break;
498 case Opt_mask:
499 ima_log_string(ab, "mask", args[0].from);
500
501 if (entry->mask)
502 result = -EINVAL;
503
504 if ((strcmp(args[0].from, "MAY_EXEC")) == 0)
505 entry->mask = MAY_EXEC;
506 else if (strcmp(args[0].from, "MAY_WRITE") == 0)
507 entry->mask = MAY_WRITE;
508 else if (strcmp(args[0].from, "MAY_READ") == 0)
509 entry->mask = MAY_READ;
510 else if (strcmp(args[0].from, "MAY_APPEND") == 0)
511 entry->mask = MAY_APPEND;
512 else
513 result = -EINVAL;
514 if (!result)
515 entry->flags |= IMA_MASK;
516 break;
517 case Opt_fsmagic:
518 ima_log_string(ab, "fsmagic", args[0].from);
519
520 if (entry->fsmagic) {
521 result = -EINVAL;
522 break;
523 }
524
525 result = kstrtoul(args[0].from, 16, &entry->fsmagic);
526 if (!result)
527 entry->flags |= IMA_FSMAGIC;
528 break;
529 case Opt_fsuuid:
530 ima_log_string(ab, "fsuuid", args[0].from);
531
532 if (memchr_inv(entry->fsuuid, 0x00,
533 sizeof(entry->fsuuid))) {
534 result = -EINVAL;
535 break;
536 }
537
538 result = blk_part_pack_uuid(args[0].from,
539 entry->fsuuid);
540 if (!result)
541 entry->flags |= IMA_FSUUID;
542 break;
543 case Opt_uid:
544 ima_log_string(ab, "uid", args[0].from);
545
546 if (uid_valid(entry->uid)) {
547 result = -EINVAL;
548 break;
549 }
550
551 result = kstrtoul(args[0].from, 10, &lnum);
552 if (!result) {
553 entry->uid = make_kuid(current_user_ns(), (uid_t)lnum);
554 if (!uid_valid(entry->uid) || (((uid_t)lnum) != lnum))
555 result = -EINVAL;
556 else
557 entry->flags |= IMA_UID;
558 }
559 break;
560 case Opt_fowner:
561 ima_log_string(ab, "fowner", args[0].from);
562
563 if (uid_valid(entry->fowner)) {
564 result = -EINVAL;
565 break;
566 }
567
568 result = kstrtoul(args[0].from, 10, &lnum);
569 if (!result) {
570 entry->fowner = make_kuid(current_user_ns(), (uid_t)lnum);
571 if (!uid_valid(entry->fowner) || (((uid_t)lnum) != lnum))
572 result = -EINVAL;
573 else
574 entry->flags |= IMA_FOWNER;
575 }
576 break;
577 case Opt_obj_user:
578 ima_log_string(ab, "obj_user", args[0].from);
579 result = ima_lsm_rule_init(entry, args,
580 LSM_OBJ_USER,
581 AUDIT_OBJ_USER);
582 break;
583 case Opt_obj_role:
584 ima_log_string(ab, "obj_role", args[0].from);
585 result = ima_lsm_rule_init(entry, args,
586 LSM_OBJ_ROLE,
587 AUDIT_OBJ_ROLE);
588 break;
589 case Opt_obj_type:
590 ima_log_string(ab, "obj_type", args[0].from);
591 result = ima_lsm_rule_init(entry, args,
592 LSM_OBJ_TYPE,
593 AUDIT_OBJ_TYPE);
594 break;
595 case Opt_subj_user:
596 ima_log_string(ab, "subj_user", args[0].from);
597 result = ima_lsm_rule_init(entry, args,
598 LSM_SUBJ_USER,
599 AUDIT_SUBJ_USER);
600 break;
601 case Opt_subj_role:
602 ima_log_string(ab, "subj_role", args[0].from);
603 result = ima_lsm_rule_init(entry, args,
604 LSM_SUBJ_ROLE,
605 AUDIT_SUBJ_ROLE);
606 break;
607 case Opt_subj_type:
608 ima_log_string(ab, "subj_type", args[0].from);
609 result = ima_lsm_rule_init(entry, args,
610 LSM_SUBJ_TYPE,
611 AUDIT_SUBJ_TYPE);
612 break;
613 case Opt_appraise_type:
614 if (entry->action != APPRAISE) {
615 result = -EINVAL;
616 break;
617 }
618
619 ima_log_string(ab, "appraise_type", args[0].from);
620 if ((strcmp(args[0].from, "imasig")) == 0)
621 entry->flags |= IMA_DIGSIG_REQUIRED;
622 else
623 result = -EINVAL;
624 break;
625 case Opt_err:
626 ima_log_string(ab, "UNKNOWN", p);
627 result = -EINVAL;
628 break;
629 }
630 }
631 if (!result && (entry->action == UNKNOWN))
632 result = -EINVAL;
633 else if (entry->func == MODULE_CHECK)
634 ima_appraise |= IMA_APPRAISE_MODULES;
635 audit_log_format(ab, "res=%d", !result);
636 audit_log_end(ab);
637 return result;
638}
639
640/**
641 * ima_parse_add_rule - add a rule to ima_policy_rules
642 * @rule - ima measurement policy rule
643 *
644 * Uses a mutex to protect the policy list from multiple concurrent writers.
645 * Returns the length of the rule parsed, an error code on failure
646 */
647ssize_t ima_parse_add_rule(char *rule)
648{
649 static const char op[] = "update_policy";
650 char *p;
651 struct ima_rule_entry *entry;
652 ssize_t result, len;
653 int audit_info = 0;
654
655 /* Prevent installed policy from changing */
656 if (ima_rules != &ima_default_rules) {
657 integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
658 NULL, op, "already exists",
659 -EACCES, audit_info);
660 return -EACCES;
661 }
662
663 entry = kzalloc(sizeof(*entry), GFP_KERNEL);
664 if (!entry) {
665 integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
666 NULL, op, "-ENOMEM", -ENOMEM, audit_info);
667 return -ENOMEM;
668 }
669
670 INIT_LIST_HEAD(&entry->list);
671
672 p = strsep(&rule, "\n");
673 len = strlen(p) + 1;
674
675 if (*p == '#') {
676 kfree(entry);
677 return len;
678 }
679
680 result = ima_parse_rule(p, entry);
681 if (result) {
682 kfree(entry);
683 integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
684 NULL, op, "invalid policy", result,
685 audit_info);
686 return result;
687 }
688
689 mutex_lock(&ima_rules_mutex);
690 list_add_tail(&entry->list, &ima_policy_rules);
691 mutex_unlock(&ima_rules_mutex);
692
693 return len;
694}
695
696/* ima_delete_rules called to cleanup invalid policy */
697void ima_delete_rules(void)
698{
699 struct ima_rule_entry *entry, *tmp;
700 int i;
701
702 mutex_lock(&ima_rules_mutex);
703 list_for_each_entry_safe(entry, tmp, &ima_policy_rules, list) {
704 for (i = 0; i < MAX_LSM_RULES; i++)
705 kfree(entry->lsm[i].args_p);
706
707 list_del(&entry->list);
708 kfree(entry);
709 }
710 mutex_unlock(&ima_rules_mutex);
711}