1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) 2008 IBM Corporation
4 * Author: Mimi Zohar <zohar@us.ibm.com>
5 *
6 * ima_policy.c
7 * - initialize default measure policy rules
8 */
9
10 #include <linux/init.h>
11 #include <linux/list.h>
12 #include <linux/kernel_read_file.h>
13 #include <linux/fs.h>
14 #include <linux/security.h>
15 #include <linux/magic.h>
16 #include <linux/parser.h>
17 #include <linux/slab.h>
18 #include <linux/rculist.h>
19 #include <linux/genhd.h>
20 #include <linux/seq_file.h>
21 #include <linux/ima.h>
22
23 #include "ima.h"
24
25 /* flags definitions */
26 #define IMA_FUNC 0x0001
27 #define IMA_MASK 0x0002
28 #define IMA_FSMAGIC 0x0004
29 #define IMA_UID 0x0008
30 #define IMA_FOWNER 0x0010
31 #define IMA_FSUUID 0x0020
32 #define IMA_INMASK 0x0040
33 #define IMA_EUID 0x0080
34 #define IMA_PCR 0x0100
35 #define IMA_FSNAME 0x0200
36 #define IMA_KEYRINGS 0x0400
37 #define IMA_LABEL 0x0800
38 #define IMA_VALIDATE_ALGOS 0x1000
39 #define IMA_GID 0x2000
40 #define IMA_EGID 0x4000
41 #define IMA_FGROUP 0x8000
42
43 #define UNKNOWN 0
44 #define MEASURE 0x0001 /* same as IMA_MEASURE */
45 #define DONT_MEASURE 0x0002
46 #define APPRAISE 0x0004 /* same as IMA_APPRAISE */
47 #define DONT_APPRAISE 0x0008
48 #define AUDIT 0x0040
49 #define HASH 0x0100
50 #define DONT_HASH 0x0200
51
52 #define INVALID_PCR(a) (((a) < 0) || \
53 (a) >= (sizeof_field(struct integrity_iint_cache, measured_pcrs) * 8))
54
55 int ima_policy_flag;
56 static int temp_ima_appraise;
57 static int build_ima_appraise __ro_after_init;
58
59 atomic_t ima_setxattr_allowed_hash_algorithms;
60
61 #define MAX_LSM_RULES 6
62 enum lsm_rule_types { LSM_OBJ_USER, LSM_OBJ_ROLE, LSM_OBJ_TYPE,
63 LSM_SUBJ_USER, LSM_SUBJ_ROLE, LSM_SUBJ_TYPE
64 };
65
66 enum policy_types { ORIGINAL_TCB = 1, DEFAULT_TCB };
67
68 enum policy_rule_list { IMA_DEFAULT_POLICY = 1, IMA_CUSTOM_POLICY };
69
70 struct ima_rule_opt_list {
71 size_t count;
72 char *items[];
73 };
74
75 struct ima_rule_entry {
76 struct list_head list;
77 int action;
78 unsigned int flags;
79 enum ima_hooks func;
80 int mask;
81 unsigned long fsmagic;
82 uuid_t fsuuid;
83 kuid_t uid;
84 kgid_t gid;
85 kuid_t fowner;
86 kgid_t fgroup;
87 bool (*uid_op)(kuid_t cred_uid, kuid_t rule_uid); /* Handlers for operators */
88 bool (*gid_op)(kgid_t cred_gid, kgid_t rule_gid);
89 bool (*fowner_op)(kuid_t cred_uid, kuid_t rule_uid); /* uid_eq(), uid_gt(), uid_lt() */
90 bool (*fgroup_op)(kgid_t cred_gid, kgid_t rule_gid); /* gid_eq(), gid_gt(), gid_lt() */
91 int pcr;
92 unsigned int allowed_algos; /* bitfield of allowed hash algorithms */
93 struct {
94 void *rule; /* LSM file metadata specific */
95 char *args_p; /* audit value */
96 int type; /* audit type */
97 } lsm[MAX_LSM_RULES];
98 char *fsname;
99 struct ima_rule_opt_list *keyrings; /* Measure keys added to these keyrings */
100 struct ima_rule_opt_list *label; /* Measure data grouped under this label */
101 struct ima_template_desc *template;
102 };
103
104 /*
105 * sanity check in case the kernels gains more hash algorithms that can
106 * fit in an unsigned int
107 */
108 static_assert(
109 8 * sizeof(unsigned int) >= HASH_ALGO__LAST,
110 "The bitfield allowed_algos in ima_rule_entry is too small to contain all the supported hash algorithms, consider using a bigger type");
111
112 /*
113 * Without LSM specific knowledge, the default policy can only be
114 * written in terms of .action, .func, .mask, .fsmagic, .uid, .gid,
115 * .fowner, and .fgroup
116 */
117
118 /*
119 * The minimum rule set to allow for full TCB coverage. Measures all files
120 * opened or mmap for exec and everything read by root. Dangerous because
121 * normal users can easily run the machine out of memory simply building
122 * and running executables.
123 */
124 static struct ima_rule_entry dont_measure_rules[] __ro_after_init = {
125 {.action = DONT_MEASURE, .fsmagic = PROC_SUPER_MAGIC, .flags = IMA_FSMAGIC},
126 {.action = DONT_MEASURE, .fsmagic = SYSFS_MAGIC, .flags = IMA_FSMAGIC},
127 {.action = DONT_MEASURE, .fsmagic = DEBUGFS_MAGIC, .flags = IMA_FSMAGIC},
128 {.action = DONT_MEASURE, .fsmagic = TMPFS_MAGIC, .flags = IMA_FSMAGIC},
129 {.action = DONT_MEASURE, .fsmagic = DEVPTS_SUPER_MAGIC, .flags = IMA_FSMAGIC},
130 {.action = DONT_MEASURE, .fsmagic = BINFMTFS_MAGIC, .flags = IMA_FSMAGIC},
131 {.action = DONT_MEASURE, .fsmagic = SECURITYFS_MAGIC, .flags = IMA_FSMAGIC},
132 {.action = DONT_MEASURE, .fsmagic = SELINUX_MAGIC, .flags = IMA_FSMAGIC},
133 {.action = DONT_MEASURE, .fsmagic = SMACK_MAGIC, .flags = IMA_FSMAGIC},
134 {.action = DONT_MEASURE, .fsmagic = CGROUP_SUPER_MAGIC,
135 .flags = IMA_FSMAGIC},
136 {.action = DONT_MEASURE, .fsmagic = CGROUP2_SUPER_MAGIC,
137 .flags = IMA_FSMAGIC},
138 {.action = DONT_MEASURE, .fsmagic = NSFS_MAGIC, .flags = IMA_FSMAGIC},
139 {.action = DONT_MEASURE, .fsmagic = EFIVARFS_MAGIC, .flags = IMA_FSMAGIC}
140 };
141
142 static struct ima_rule_entry original_measurement_rules[] __ro_after_init = {
143 {.action = MEASURE, .func = MMAP_CHECK, .mask = MAY_EXEC,
144 .flags = IMA_FUNC | IMA_MASK},
145 {.action = MEASURE, .func = BPRM_CHECK, .mask = MAY_EXEC,
146 .flags = IMA_FUNC | IMA_MASK},
147 {.action = MEASURE, .func = FILE_CHECK, .mask = MAY_READ,
148 .uid = GLOBAL_ROOT_UID, .uid_op = &uid_eq,
149 .flags = IMA_FUNC | IMA_MASK | IMA_UID},
150 {.action = MEASURE, .func = MODULE_CHECK, .flags = IMA_FUNC},
151 {.action = MEASURE, .func = FIRMWARE_CHECK, .flags = IMA_FUNC},
152 };
153
154 static struct ima_rule_entry default_measurement_rules[] __ro_after_init = {
155 {.action = MEASURE, .func = MMAP_CHECK, .mask = MAY_EXEC,
156 .flags = IMA_FUNC | IMA_MASK},
157 {.action = MEASURE, .func = BPRM_CHECK, .mask = MAY_EXEC,
158 .flags = IMA_FUNC | IMA_MASK},
159 {.action = MEASURE, .func = FILE_CHECK, .mask = MAY_READ,
160 .uid = GLOBAL_ROOT_UID, .uid_op = &uid_eq,
161 .flags = IMA_FUNC | IMA_INMASK | IMA_EUID},
162 {.action = MEASURE, .func = FILE_CHECK, .mask = MAY_READ,
163 .uid = GLOBAL_ROOT_UID, .uid_op = &uid_eq,
164 .flags = IMA_FUNC | IMA_INMASK | IMA_UID},
165 {.action = MEASURE, .func = MODULE_CHECK, .flags = IMA_FUNC},
166 {.action = MEASURE, .func = FIRMWARE_CHECK, .flags = IMA_FUNC},
167 {.action = MEASURE, .func = POLICY_CHECK, .flags = IMA_FUNC},
168 };
169
170 static struct ima_rule_entry default_appraise_rules[] __ro_after_init = {
171 {.action = DONT_APPRAISE, .fsmagic = PROC_SUPER_MAGIC, .flags = IMA_FSMAGIC},
172 {.action = DONT_APPRAISE, .fsmagic = SYSFS_MAGIC, .flags = IMA_FSMAGIC},
173 {.action = DONT_APPRAISE, .fsmagic = DEBUGFS_MAGIC, .flags = IMA_FSMAGIC},
174 {.action = DONT_APPRAISE, .fsmagic = TMPFS_MAGIC, .flags = IMA_FSMAGIC},
175 {.action = DONT_APPRAISE, .fsmagic = RAMFS_MAGIC, .flags = IMA_FSMAGIC},
176 {.action = DONT_APPRAISE, .fsmagic = DEVPTS_SUPER_MAGIC, .flags = IMA_FSMAGIC},
177 {.action = DONT_APPRAISE, .fsmagic = BINFMTFS_MAGIC, .flags = IMA_FSMAGIC},
178 {.action = DONT_APPRAISE, .fsmagic = SECURITYFS_MAGIC, .flags = IMA_FSMAGIC},
179 {.action = DONT_APPRAISE, .fsmagic = SELINUX_MAGIC, .flags = IMA_FSMAGIC},
180 {.action = DONT_APPRAISE, .fsmagic = SMACK_MAGIC, .flags = IMA_FSMAGIC},
181 {.action = DONT_APPRAISE, .fsmagic = NSFS_MAGIC, .flags = IMA_FSMAGIC},
182 {.action = DONT_APPRAISE, .fsmagic = EFIVARFS_MAGIC, .flags = IMA_FSMAGIC},
183 {.action = DONT_APPRAISE, .fsmagic = CGROUP_SUPER_MAGIC, .flags = IMA_FSMAGIC},
184 {.action = DONT_APPRAISE, .fsmagic = CGROUP2_SUPER_MAGIC, .flags = IMA_FSMAGIC},
185 #ifdef CONFIG_IMA_WRITE_POLICY
186 {.action = APPRAISE, .func = POLICY_CHECK,
187 .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
188 #endif
189 #ifndef CONFIG_IMA_APPRAISE_SIGNED_INIT
190 {.action = APPRAISE, .fowner = GLOBAL_ROOT_UID, .fowner_op = &uid_eq,
191 .flags = IMA_FOWNER},
192 #else
193 /* force signature */
194 {.action = APPRAISE, .fowner = GLOBAL_ROOT_UID, .fowner_op = &uid_eq,
195 .flags = IMA_FOWNER | IMA_DIGSIG_REQUIRED},
196 #endif
197 };
198
199 static struct ima_rule_entry build_appraise_rules[] __ro_after_init = {
200 #ifdef CONFIG_IMA_APPRAISE_REQUIRE_MODULE_SIGS
201 {.action = APPRAISE, .func = MODULE_CHECK,
202 .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
203 #endif
204 #ifdef CONFIG_IMA_APPRAISE_REQUIRE_FIRMWARE_SIGS
205 {.action = APPRAISE, .func = FIRMWARE_CHECK,
206 .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
207 #endif
208 #ifdef CONFIG_IMA_APPRAISE_REQUIRE_KEXEC_SIGS
209 {.action = APPRAISE, .func = KEXEC_KERNEL_CHECK,
210 .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
211 #endif
212 #ifdef CONFIG_IMA_APPRAISE_REQUIRE_POLICY_SIGS
213 {.action = APPRAISE, .func = POLICY_CHECK,
214 .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
215 #endif
216 };
217
218 static struct ima_rule_entry secure_boot_rules[] __ro_after_init = {
219 {.action = APPRAISE, .func = MODULE_CHECK,
220 .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
221 {.action = APPRAISE, .func = FIRMWARE_CHECK,
222 .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
223 {.action = APPRAISE, .func = KEXEC_KERNEL_CHECK,
224 .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
225 {.action = APPRAISE, .func = POLICY_CHECK,
226 .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
227 };
228
229 static struct ima_rule_entry critical_data_rules[] __ro_after_init = {
230 {.action = MEASURE, .func = CRITICAL_DATA, .flags = IMA_FUNC},
231 };
232
233 /* An array of architecture specific rules */
234 static struct ima_rule_entry *arch_policy_entry __ro_after_init;
235
236 static LIST_HEAD(ima_default_rules);
237 static LIST_HEAD(ima_policy_rules);
238 static LIST_HEAD(ima_temp_rules);
239 static struct list_head __rcu *ima_rules = (struct list_head __rcu *)(&ima_default_rules);
240
241 static int ima_policy __initdata;
242
default_measure_policy_setup(char * str)243 static int __init default_measure_policy_setup(char *str)
244 {
245 if (ima_policy)
246 return 1;
247
248 ima_policy = ORIGINAL_TCB;
249 return 1;
250 }
251 __setup("ima_tcb", default_measure_policy_setup);
252
253 static bool ima_use_appraise_tcb __initdata;
254 static bool ima_use_secure_boot __initdata;
255 static bool ima_use_critical_data __initdata;
256 static bool ima_fail_unverifiable_sigs __ro_after_init;
policy_setup(char * str)257 static int __init policy_setup(char *str)
258 {
259 char *p;
260
261 while ((p = strsep(&str, " |\n")) != NULL) {
262 if (*p == ' ')
263 continue;
264 if ((strcmp(p, "tcb") == 0) && !ima_policy)
265 ima_policy = DEFAULT_TCB;
266 else if (strcmp(p, "appraise_tcb") == 0)
267 ima_use_appraise_tcb = true;
268 else if (strcmp(p, "secure_boot") == 0)
269 ima_use_secure_boot = true;
270 else if (strcmp(p, "critical_data") == 0)
271 ima_use_critical_data = true;
272 else if (strcmp(p, "fail_securely") == 0)
273 ima_fail_unverifiable_sigs = true;
274 else
275 pr_err("policy \"%s\" not found", p);
276 }
277
278 return 1;
279 }
280 __setup("ima_policy=", policy_setup);
281
default_appraise_policy_setup(char * str)282 static int __init default_appraise_policy_setup(char *str)
283 {
284 ima_use_appraise_tcb = true;
285 return 1;
286 }
287 __setup("ima_appraise_tcb", default_appraise_policy_setup);
288
ima_alloc_rule_opt_list(const substring_t * src)289 static struct ima_rule_opt_list *ima_alloc_rule_opt_list(const substring_t *src)
290 {
291 struct ima_rule_opt_list *opt_list;
292 size_t count = 0;
293 char *src_copy;
294 char *cur, *next;
295 size_t i;
296
297 src_copy = match_strdup(src);
298 if (!src_copy)
299 return ERR_PTR(-ENOMEM);
300
301 next = src_copy;
302 while ((cur = strsep(&next, "|"))) {
303 /* Don't accept an empty list item */
304 if (!(*cur)) {
305 kfree(src_copy);
306 return ERR_PTR(-EINVAL);
307 }
308 count++;
309 }
310
311 /* Don't accept an empty list */
312 if (!count) {
313 kfree(src_copy);
314 return ERR_PTR(-EINVAL);
315 }
316
317 opt_list = kzalloc(struct_size(opt_list, items, count), GFP_KERNEL);
318 if (!opt_list) {
319 kfree(src_copy);
320 return ERR_PTR(-ENOMEM);
321 }
322
323 /*
324 * strsep() has already replaced all instances of '|' with '\0',
325 * leaving a byte sequence of NUL-terminated strings. Reference each
326 * string with the array of items.
327 *
328 * IMPORTANT: Ownership of the allocated buffer is transferred from
329 * src_copy to the first element in the items array. To free the
330 * buffer, kfree() must only be called on the first element of the
331 * array.
332 */
333 for (i = 0, cur = src_copy; i < count; i++) {
334 opt_list->items[i] = cur;
335 cur = strchr(cur, '\0') + 1;
336 }
337 opt_list->count = count;
338
339 return opt_list;
340 }
341
ima_free_rule_opt_list(struct ima_rule_opt_list * opt_list)342 static void ima_free_rule_opt_list(struct ima_rule_opt_list *opt_list)
343 {
344 if (!opt_list)
345 return;
346
347 if (opt_list->count) {
348 kfree(opt_list->items[0]);
349 opt_list->count = 0;
350 }
351
352 kfree(opt_list);
353 }
354
ima_lsm_free_rule(struct ima_rule_entry * entry)355 static void ima_lsm_free_rule(struct ima_rule_entry *entry)
356 {
357 int i;
358
359 for (i = 0; i < MAX_LSM_RULES; i++) {
360 ima_filter_rule_free(entry->lsm[i].rule);
361 kfree(entry->lsm[i].args_p);
362 }
363 }
364
ima_free_rule(struct ima_rule_entry * entry)365 static void ima_free_rule(struct ima_rule_entry *entry)
366 {
367 if (!entry)
368 return;
369
370 /*
371 * entry->template->fields may be allocated in ima_parse_rule() but that
372 * reference is owned by the corresponding ima_template_desc element in
373 * the defined_templates list and cannot be freed here
374 */
375 kfree(entry->fsname);
376 ima_free_rule_opt_list(entry->keyrings);
377 ima_lsm_free_rule(entry);
378 kfree(entry);
379 }
380
ima_lsm_copy_rule(struct ima_rule_entry * entry)381 static struct ima_rule_entry *ima_lsm_copy_rule(struct ima_rule_entry *entry)
382 {
383 struct ima_rule_entry *nentry;
384 int i;
385
386 /*
387 * Immutable elements are copied over as pointers and data; only
388 * lsm rules can change
389 */
390 nentry = kmemdup(entry, sizeof(*nentry), GFP_KERNEL);
391 if (!nentry)
392 return NULL;
393
394 memset(nentry->lsm, 0, sizeof_field(struct ima_rule_entry, lsm));
395
396 for (i = 0; i < MAX_LSM_RULES; i++) {
397 if (!entry->lsm[i].args_p)
398 continue;
399
400 nentry->lsm[i].type = entry->lsm[i].type;
401 nentry->lsm[i].args_p = entry->lsm[i].args_p;
402 /*
403 * Remove the reference from entry so that the associated
404 * memory will not be freed during a later call to
405 * ima_lsm_free_rule(entry).
406 */
407 entry->lsm[i].args_p = NULL;
408
409 ima_filter_rule_init(nentry->lsm[i].type, Audit_equal,
410 nentry->lsm[i].args_p,
411 &nentry->lsm[i].rule);
412 if (!nentry->lsm[i].rule)
413 pr_warn("rule for LSM \'%s\' is undefined\n",
414 nentry->lsm[i].args_p);
415 }
416 return nentry;
417 }
418
ima_lsm_update_rule(struct ima_rule_entry * entry)419 static int ima_lsm_update_rule(struct ima_rule_entry *entry)
420 {
421 struct ima_rule_entry *nentry;
422
423 nentry = ima_lsm_copy_rule(entry);
424 if (!nentry)
425 return -ENOMEM;
426
427 list_replace_rcu(&entry->list, &nentry->list);
428 synchronize_rcu();
429 /*
430 * ima_lsm_copy_rule() shallow copied all references, except for the
431 * LSM references, from entry to nentry so we only want to free the LSM
432 * references and the entry itself. All other memory refrences will now
433 * be owned by nentry.
434 */
435 ima_lsm_free_rule(entry);
436 kfree(entry);
437
438 return 0;
439 }
440
ima_rule_contains_lsm_cond(struct ima_rule_entry * entry)441 static bool ima_rule_contains_lsm_cond(struct ima_rule_entry *entry)
442 {
443 int i;
444
445 for (i = 0; i < MAX_LSM_RULES; i++)
446 if (entry->lsm[i].args_p)
447 return true;
448
449 return false;
450 }
451
452 /*
453 * The LSM policy can be reloaded, leaving the IMA LSM based rules referring
454 * to the old, stale LSM policy. Update the IMA LSM based rules to reflect
455 * the reloaded LSM policy.
456 */
ima_lsm_update_rules(void)457 static void ima_lsm_update_rules(void)
458 {
459 struct ima_rule_entry *entry, *e;
460 int result;
461
462 list_for_each_entry_safe(entry, e, &ima_policy_rules, list) {
463 if (!ima_rule_contains_lsm_cond(entry))
464 continue;
465
466 result = ima_lsm_update_rule(entry);
467 if (result) {
468 pr_err("lsm rule update error %d\n", result);
469 return;
470 }
471 }
472 }
473
ima_lsm_policy_change(struct notifier_block * nb,unsigned long event,void * lsm_data)474 int ima_lsm_policy_change(struct notifier_block *nb, unsigned long event,
475 void *lsm_data)
476 {
477 if (event != LSM_POLICY_CHANGE)
478 return NOTIFY_DONE;
479
480 ima_lsm_update_rules();
481 return NOTIFY_OK;
482 }
483
484 /**
485 * ima_match_rule_data - determine whether func_data matches the policy rule
486 * @rule: a pointer to a rule
487 * @func_data: data to match against the measure rule data
488 * @cred: a pointer to a credentials structure for user validation
489 *
490 * Returns true if func_data matches one in the rule, false otherwise.
491 */
ima_match_rule_data(struct ima_rule_entry * rule,const char * func_data,const struct cred * cred)492 static bool ima_match_rule_data(struct ima_rule_entry *rule,
493 const char *func_data,
494 const struct cred *cred)
495 {
496 const struct ima_rule_opt_list *opt_list = NULL;
497 bool matched = false;
498 size_t i;
499
500 if ((rule->flags & IMA_UID) && !rule->uid_op(cred->uid, rule->uid))
501 return false;
502
503 switch (rule->func) {
504 case KEY_CHECK:
505 if (!rule->keyrings)
506 return true;
507
508 opt_list = rule->keyrings;
509 break;
510 case CRITICAL_DATA:
511 if (!rule->label)
512 return true;
513
514 opt_list = rule->label;
515 break;
516 default:
517 return false;
518 }
519
520 if (!func_data)
521 return false;
522
523 for (i = 0; i < opt_list->count; i++) {
524 if (!strcmp(opt_list->items[i], func_data)) {
525 matched = true;
526 break;
527 }
528 }
529
530 return matched;
531 }
532
533 /**
534 * ima_match_rules - determine whether an inode matches the policy rule.
535 * @rule: a pointer to a rule
536 * @mnt_userns: user namespace of the mount the inode was found from
537 * @inode: a pointer to an inode
538 * @cred: a pointer to a credentials structure for user validation
539 * @secid: the secid of the task to be validated
540 * @func: LIM hook identifier
541 * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC)
542 * @func_data: func specific data, may be NULL
543 *
544 * Returns true on rule match, false on failure.
545 */
ima_match_rules(struct ima_rule_entry * rule,struct user_namespace * mnt_userns,struct inode * inode,const struct cred * cred,u32 secid,enum ima_hooks func,int mask,const char * func_data)546 static bool ima_match_rules(struct ima_rule_entry *rule,
547 struct user_namespace *mnt_userns,
548 struct inode *inode, const struct cred *cred,
549 u32 secid, enum ima_hooks func, int mask,
550 const char *func_data)
551 {
552 int i;
553
554 if ((rule->flags & IMA_FUNC) &&
555 (rule->func != func && func != POST_SETATTR))
556 return false;
557
558 switch (func) {
559 case KEY_CHECK:
560 case CRITICAL_DATA:
561 return ((rule->func == func) &&
562 ima_match_rule_data(rule, func_data, cred));
563 default:
564 break;
565 }
566
567 if ((rule->flags & IMA_MASK) &&
568 (rule->mask != mask && func != POST_SETATTR))
569 return false;
570 if ((rule->flags & IMA_INMASK) &&
571 (!(rule->mask & mask) && func != POST_SETATTR))
572 return false;
573 if ((rule->flags & IMA_FSMAGIC)
574 && rule->fsmagic != inode->i_sb->s_magic)
575 return false;
576 if ((rule->flags & IMA_FSNAME)
577 && strcmp(rule->fsname, inode->i_sb->s_type->name))
578 return false;
579 if ((rule->flags & IMA_FSUUID) &&
580 !uuid_equal(&rule->fsuuid, &inode->i_sb->s_uuid))
581 return false;
582 if ((rule->flags & IMA_UID) && !rule->uid_op(cred->uid, rule->uid))
583 return false;
584 if (rule->flags & IMA_EUID) {
585 if (has_capability_noaudit(current, CAP_SETUID)) {
586 if (!rule->uid_op(cred->euid, rule->uid)
587 && !rule->uid_op(cred->suid, rule->uid)
588 && !rule->uid_op(cred->uid, rule->uid))
589 return false;
590 } else if (!rule->uid_op(cred->euid, rule->uid))
591 return false;
592 }
593 if ((rule->flags & IMA_GID) && !rule->gid_op(cred->gid, rule->gid))
594 return false;
595 if (rule->flags & IMA_EGID) {
596 if (has_capability_noaudit(current, CAP_SETGID)) {
597 if (!rule->gid_op(cred->egid, rule->gid)
598 && !rule->gid_op(cred->sgid, rule->gid)
599 && !rule->gid_op(cred->gid, rule->gid))
600 return false;
601 } else if (!rule->gid_op(cred->egid, rule->gid))
602 return false;
603 }
604 if ((rule->flags & IMA_FOWNER) &&
605 !rule->fowner_op(i_uid_into_mnt(mnt_userns, inode), rule->fowner))
606 return false;
607 if ((rule->flags & IMA_FGROUP) &&
608 !rule->fgroup_op(i_gid_into_mnt(mnt_userns, inode), rule->fgroup))
609 return false;
610 for (i = 0; i < MAX_LSM_RULES; i++) {
611 int rc = 0;
612 u32 osid;
613
614 if (!rule->lsm[i].rule) {
615 if (!rule->lsm[i].args_p)
616 continue;
617 else
618 return false;
619 }
620 switch (i) {
621 case LSM_OBJ_USER:
622 case LSM_OBJ_ROLE:
623 case LSM_OBJ_TYPE:
624 security_inode_getsecid(inode, &osid);
625 rc = ima_filter_rule_match(osid, rule->lsm[i].type,
626 Audit_equal,
627 rule->lsm[i].rule);
628 break;
629 case LSM_SUBJ_USER:
630 case LSM_SUBJ_ROLE:
631 case LSM_SUBJ_TYPE:
632 rc = ima_filter_rule_match(secid, rule->lsm[i].type,
633 Audit_equal,
634 rule->lsm[i].rule);
635 break;
636 default:
637 break;
638 }
639 if (!rc)
640 return false;
641 }
642 return true;
643 }
644
645 /*
646 * In addition to knowing that we need to appraise the file in general,
647 * we need to differentiate between calling hooks, for hook specific rules.
648 */
get_subaction(struct ima_rule_entry * rule,enum ima_hooks func)649 static int get_subaction(struct ima_rule_entry *rule, enum ima_hooks func)
650 {
651 if (!(rule->flags & IMA_FUNC))
652 return IMA_FILE_APPRAISE;
653
654 switch (func) {
655 case MMAP_CHECK:
656 return IMA_MMAP_APPRAISE;
657 case BPRM_CHECK:
658 return IMA_BPRM_APPRAISE;
659 case CREDS_CHECK:
660 return IMA_CREDS_APPRAISE;
661 case FILE_CHECK:
662 case POST_SETATTR:
663 return IMA_FILE_APPRAISE;
664 case MODULE_CHECK ... MAX_CHECK - 1:
665 default:
666 return IMA_READ_APPRAISE;
667 }
668 }
669
670 /**
671 * ima_match_policy - decision based on LSM and other conditions
672 * @mnt_userns: user namespace of the mount the inode was found from
673 * @inode: pointer to an inode for which the policy decision is being made
674 * @cred: pointer to a credentials structure for which the policy decision is
675 * being made
676 * @secid: LSM secid of the task to be validated
677 * @func: IMA hook identifier
678 * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC)
679 * @pcr: set the pcr to extend
680 * @template_desc: the template that should be used for this rule
681 * @func_data: func specific data, may be NULL
682 * @allowed_algos: allowlist of hash algorithms for the IMA xattr
683 *
684 * Measure decision based on func/mask/fsmagic and LSM(subj/obj/type)
685 * conditions.
686 *
687 * Since the IMA policy may be updated multiple times we need to lock the
688 * list when walking it. Reads are many orders of magnitude more numerous
689 * than writes so ima_match_policy() is classical RCU candidate.
690 */
ima_match_policy(struct user_namespace * mnt_userns,struct inode * inode,const struct cred * cred,u32 secid,enum ima_hooks func,int mask,int flags,int * pcr,struct ima_template_desc ** template_desc,const char * func_data,unsigned int * allowed_algos)691 int ima_match_policy(struct user_namespace *mnt_userns, struct inode *inode,
692 const struct cred *cred, u32 secid, enum ima_hooks func,
693 int mask, int flags, int *pcr,
694 struct ima_template_desc **template_desc,
695 const char *func_data, unsigned int *allowed_algos)
696 {
697 struct ima_rule_entry *entry;
698 int action = 0, actmask = flags | (flags << 1);
699 struct list_head *ima_rules_tmp;
700
701 if (template_desc && !*template_desc)
702 *template_desc = ima_template_desc_current();
703
704 rcu_read_lock();
705 ima_rules_tmp = rcu_dereference(ima_rules);
706 list_for_each_entry_rcu(entry, ima_rules_tmp, list) {
707
708 if (!(entry->action & actmask))
709 continue;
710
711 if (!ima_match_rules(entry, mnt_userns, inode, cred, secid,
712 func, mask, func_data))
713 continue;
714
715 action |= entry->flags & IMA_ACTION_FLAGS;
716
717 action |= entry->action & IMA_DO_MASK;
718 if (entry->action & IMA_APPRAISE) {
719 action |= get_subaction(entry, func);
720 action &= ~IMA_HASH;
721 if (ima_fail_unverifiable_sigs)
722 action |= IMA_FAIL_UNVERIFIABLE_SIGS;
723
724 if (allowed_algos &&
725 entry->flags & IMA_VALIDATE_ALGOS)
726 *allowed_algos = entry->allowed_algos;
727 }
728
729 if (entry->action & IMA_DO_MASK)
730 actmask &= ~(entry->action | entry->action << 1);
731 else
732 actmask &= ~(entry->action | entry->action >> 1);
733
734 if ((pcr) && (entry->flags & IMA_PCR))
735 *pcr = entry->pcr;
736
737 if (template_desc && entry->template)
738 *template_desc = entry->template;
739
740 if (!actmask)
741 break;
742 }
743 rcu_read_unlock();
744
745 return action;
746 }
747
748 /**
749 * ima_update_policy_flags() - Update global IMA variables
750 *
751 * Update ima_policy_flag and ima_setxattr_allowed_hash_algorithms
752 * based on the currently loaded policy.
753 *
754 * With ima_policy_flag, the decision to short circuit out of a function
755 * or not call the function in the first place can be made earlier.
756 *
757 * With ima_setxattr_allowed_hash_algorithms, the policy can restrict the
758 * set of hash algorithms accepted when updating the security.ima xattr of
759 * a file.
760 *
761 * Context: called after a policy update and at system initialization.
762 */
ima_update_policy_flags(void)763 void ima_update_policy_flags(void)
764 {
765 struct ima_rule_entry *entry;
766 int new_policy_flag = 0;
767 struct list_head *ima_rules_tmp;
768
769 rcu_read_lock();
770 ima_rules_tmp = rcu_dereference(ima_rules);
771 list_for_each_entry_rcu(entry, ima_rules_tmp, list) {
772 /*
773 * SETXATTR_CHECK rules do not implement a full policy check
774 * because rule checking would probably have an important
775 * performance impact on setxattr(). As a consequence, only one
776 * SETXATTR_CHECK can be active at a given time.
777 * Because we want to preserve that property, we set out to use
778 * atomic_cmpxchg. Either:
779 * - the atomic was non-zero: a setxattr hash policy is
780 * already enforced, we do nothing
781 * - the atomic was zero: no setxattr policy was set, enable
782 * the setxattr hash policy
783 */
784 if (entry->func == SETXATTR_CHECK) {
785 atomic_cmpxchg(&ima_setxattr_allowed_hash_algorithms,
786 0, entry->allowed_algos);
787 /* SETXATTR_CHECK doesn't impact ima_policy_flag */
788 continue;
789 }
790
791 if (entry->action & IMA_DO_MASK)
792 new_policy_flag |= entry->action;
793 }
794 rcu_read_unlock();
795
796 ima_appraise |= (build_ima_appraise | temp_ima_appraise);
797 if (!ima_appraise)
798 new_policy_flag &= ~IMA_APPRAISE;
799
800 ima_policy_flag = new_policy_flag;
801 }
802
ima_appraise_flag(enum ima_hooks func)803 static int ima_appraise_flag(enum ima_hooks func)
804 {
805 if (func == MODULE_CHECK)
806 return IMA_APPRAISE_MODULES;
807 else if (func == FIRMWARE_CHECK)
808 return IMA_APPRAISE_FIRMWARE;
809 else if (func == POLICY_CHECK)
810 return IMA_APPRAISE_POLICY;
811 else if (func == KEXEC_KERNEL_CHECK)
812 return IMA_APPRAISE_KEXEC;
813 return 0;
814 }
815
add_rules(struct ima_rule_entry * entries,int count,enum policy_rule_list policy_rule)816 static void add_rules(struct ima_rule_entry *entries, int count,
817 enum policy_rule_list policy_rule)
818 {
819 int i = 0;
820
821 for (i = 0; i < count; i++) {
822 struct ima_rule_entry *entry;
823
824 if (policy_rule & IMA_DEFAULT_POLICY)
825 list_add_tail(&entries[i].list, &ima_default_rules);
826
827 if (policy_rule & IMA_CUSTOM_POLICY) {
828 entry = kmemdup(&entries[i], sizeof(*entry),
829 GFP_KERNEL);
830 if (!entry)
831 continue;
832
833 list_add_tail(&entry->list, &ima_policy_rules);
834 }
835 if (entries[i].action == APPRAISE) {
836 if (entries != build_appraise_rules)
837 temp_ima_appraise |=
838 ima_appraise_flag(entries[i].func);
839 else
840 build_ima_appraise |=
841 ima_appraise_flag(entries[i].func);
842 }
843 }
844 }
845
846 static int ima_parse_rule(char *rule, struct ima_rule_entry *entry);
847
ima_init_arch_policy(void)848 static int __init ima_init_arch_policy(void)
849 {
850 const char * const *arch_rules;
851 const char * const *rules;
852 int arch_entries = 0;
853 int i = 0;
854
855 arch_rules = arch_get_ima_policy();
856 if (!arch_rules)
857 return arch_entries;
858
859 /* Get number of rules */
860 for (rules = arch_rules; *rules != NULL; rules++)
861 arch_entries++;
862
863 arch_policy_entry = kcalloc(arch_entries + 1,
864 sizeof(*arch_policy_entry), GFP_KERNEL);
865 if (!arch_policy_entry)
866 return 0;
867
868 /* Convert each policy string rules to struct ima_rule_entry format */
869 for (rules = arch_rules, i = 0; *rules != NULL; rules++) {
870 char rule[255];
871 int result;
872
873 result = strscpy(rule, *rules, sizeof(rule));
874
875 INIT_LIST_HEAD(&arch_policy_entry[i].list);
876 result = ima_parse_rule(rule, &arch_policy_entry[i]);
877 if (result) {
878 pr_warn("Skipping unknown architecture policy rule: %s\n",
879 rule);
880 memset(&arch_policy_entry[i], 0,
881 sizeof(*arch_policy_entry));
882 continue;
883 }
884 i++;
885 }
886 return i;
887 }
888
889 /**
890 * ima_init_policy - initialize the default measure rules.
891 *
892 * ima_rules points to either the ima_default_rules or the new ima_policy_rules.
893 */
ima_init_policy(void)894 void __init ima_init_policy(void)
895 {
896 int build_appraise_entries, arch_entries;
897
898 /* if !ima_policy, we load NO default rules */
899 if (ima_policy)
900 add_rules(dont_measure_rules, ARRAY_SIZE(dont_measure_rules),
901 IMA_DEFAULT_POLICY);
902
903 switch (ima_policy) {
904 case ORIGINAL_TCB:
905 add_rules(original_measurement_rules,
906 ARRAY_SIZE(original_measurement_rules),
907 IMA_DEFAULT_POLICY);
908 break;
909 case DEFAULT_TCB:
910 add_rules(default_measurement_rules,
911 ARRAY_SIZE(default_measurement_rules),
912 IMA_DEFAULT_POLICY);
913 break;
914 default:
915 break;
916 }
917
918 /*
919 * Based on runtime secure boot flags, insert arch specific measurement
920 * and appraise rules requiring file signatures for both the initial
921 * and custom policies, prior to other appraise rules.
922 * (Highest priority)
923 */
924 arch_entries = ima_init_arch_policy();
925 if (!arch_entries)
926 pr_info("No architecture policies found\n");
927 else
928 add_rules(arch_policy_entry, arch_entries,
929 IMA_DEFAULT_POLICY | IMA_CUSTOM_POLICY);
930
931 /*
932 * Insert the builtin "secure_boot" policy rules requiring file
933 * signatures, prior to other appraise rules.
934 */
935 if (ima_use_secure_boot)
936 add_rules(secure_boot_rules, ARRAY_SIZE(secure_boot_rules),
937 IMA_DEFAULT_POLICY);
938
939 /*
940 * Insert the build time appraise rules requiring file signatures
941 * for both the initial and custom policies, prior to other appraise
942 * rules. As the secure boot rules includes all of the build time
943 * rules, include either one or the other set of rules, but not both.
944 */
945 build_appraise_entries = ARRAY_SIZE(build_appraise_rules);
946 if (build_appraise_entries) {
947 if (ima_use_secure_boot)
948 add_rules(build_appraise_rules, build_appraise_entries,
949 IMA_CUSTOM_POLICY);
950 else
951 add_rules(build_appraise_rules, build_appraise_entries,
952 IMA_DEFAULT_POLICY | IMA_CUSTOM_POLICY);
953 }
954
955 if (ima_use_appraise_tcb)
956 add_rules(default_appraise_rules,
957 ARRAY_SIZE(default_appraise_rules),
958 IMA_DEFAULT_POLICY);
959
960 if (ima_use_critical_data)
961 add_rules(critical_data_rules,
962 ARRAY_SIZE(critical_data_rules),
963 IMA_DEFAULT_POLICY);
964
965 atomic_set(&ima_setxattr_allowed_hash_algorithms, 0);
966
967 ima_update_policy_flags();
968 }
969
970 /* Make sure we have a valid policy, at least containing some rules. */
ima_check_policy(void)971 int ima_check_policy(void)
972 {
973 if (list_empty(&ima_temp_rules))
974 return -EINVAL;
975 return 0;
976 }
977
978 /**
979 * ima_update_policy - update default_rules with new measure rules
980 *
981 * Called on file .release to update the default rules with a complete new
982 * policy. What we do here is to splice ima_policy_rules and ima_temp_rules so
983 * they make a queue. The policy may be updated multiple times and this is the
984 * RCU updater.
985 *
986 * Policy rules are never deleted so ima_policy_flag gets zeroed only once when
987 * we switch from the default policy to user defined.
988 */
ima_update_policy(void)989 void ima_update_policy(void)
990 {
991 struct list_head *policy = &ima_policy_rules;
992
993 list_splice_tail_init_rcu(&ima_temp_rules, policy, synchronize_rcu);
994
995 if (ima_rules != (struct list_head __rcu *)policy) {
996 ima_policy_flag = 0;
997
998 rcu_assign_pointer(ima_rules, policy);
999 /*
1000 * IMA architecture specific policy rules are specified
1001 * as strings and converted to an array of ima_entry_rules
1002 * on boot. After loading a custom policy, free the
1003 * architecture specific rules stored as an array.
1004 */
1005 kfree(arch_policy_entry);
1006 }
1007 ima_update_policy_flags();
1008
1009 /* Custom IMA policy has been loaded */
1010 ima_process_queued_keys();
1011 }
1012
1013 /* Keep the enumeration in sync with the policy_tokens! */
1014 enum policy_opt {
1015 Opt_measure, Opt_dont_measure,
1016 Opt_appraise, Opt_dont_appraise,
1017 Opt_audit, Opt_hash, Opt_dont_hash,
1018 Opt_obj_user, Opt_obj_role, Opt_obj_type,
1019 Opt_subj_user, Opt_subj_role, Opt_subj_type,
1020 Opt_func, Opt_mask, Opt_fsmagic, Opt_fsname, Opt_fsuuid,
1021 Opt_uid_eq, Opt_euid_eq, Opt_gid_eq, Opt_egid_eq,
1022 Opt_fowner_eq, Opt_fgroup_eq,
1023 Opt_uid_gt, Opt_euid_gt, Opt_gid_gt, Opt_egid_gt,
1024 Opt_fowner_gt, Opt_fgroup_gt,
1025 Opt_uid_lt, Opt_euid_lt, Opt_gid_lt, Opt_egid_lt,
1026 Opt_fowner_lt, Opt_fgroup_lt,
1027 Opt_appraise_type, Opt_appraise_flag, Opt_appraise_algos,
1028 Opt_permit_directio, Opt_pcr, Opt_template, Opt_keyrings,
1029 Opt_label, Opt_err
1030 };
1031
1032 static const match_table_t policy_tokens = {
1033 {Opt_measure, "measure"},
1034 {Opt_dont_measure, "dont_measure"},
1035 {Opt_appraise, "appraise"},
1036 {Opt_dont_appraise, "dont_appraise"},
1037 {Opt_audit, "audit"},
1038 {Opt_hash, "hash"},
1039 {Opt_dont_hash, "dont_hash"},
1040 {Opt_obj_user, "obj_user=%s"},
1041 {Opt_obj_role, "obj_role=%s"},
1042 {Opt_obj_type, "obj_type=%s"},
1043 {Opt_subj_user, "subj_user=%s"},
1044 {Opt_subj_role, "subj_role=%s"},
1045 {Opt_subj_type, "subj_type=%s"},
1046 {Opt_func, "func=%s"},
1047 {Opt_mask, "mask=%s"},
1048 {Opt_fsmagic, "fsmagic=%s"},
1049 {Opt_fsname, "fsname=%s"},
1050 {Opt_fsuuid, "fsuuid=%s"},
1051 {Opt_uid_eq, "uid=%s"},
1052 {Opt_euid_eq, "euid=%s"},
1053 {Opt_gid_eq, "gid=%s"},
1054 {Opt_egid_eq, "egid=%s"},
1055 {Opt_fowner_eq, "fowner=%s"},
1056 {Opt_fgroup_eq, "fgroup=%s"},
1057 {Opt_uid_gt, "uid>%s"},
1058 {Opt_euid_gt, "euid>%s"},
1059 {Opt_gid_gt, "gid>%s"},
1060 {Opt_egid_gt, "egid>%s"},
1061 {Opt_fowner_gt, "fowner>%s"},
1062 {Opt_fgroup_gt, "fgroup>%s"},
1063 {Opt_uid_lt, "uid<%s"},
1064 {Opt_euid_lt, "euid<%s"},
1065 {Opt_gid_lt, "gid<%s"},
1066 {Opt_egid_lt, "egid<%s"},
1067 {Opt_fowner_lt, "fowner<%s"},
1068 {Opt_fgroup_lt, "fgroup<%s"},
1069 {Opt_appraise_type, "appraise_type=%s"},
1070 {Opt_appraise_flag, "appraise_flag=%s"},
1071 {Opt_appraise_algos, "appraise_algos=%s"},
1072 {Opt_permit_directio, "permit_directio"},
1073 {Opt_pcr, "pcr=%s"},
1074 {Opt_template, "template=%s"},
1075 {Opt_keyrings, "keyrings=%s"},
1076 {Opt_label, "label=%s"},
1077 {Opt_err, NULL}
1078 };
1079
ima_lsm_rule_init(struct ima_rule_entry * entry,substring_t * args,int lsm_rule,int audit_type)1080 static int ima_lsm_rule_init(struct ima_rule_entry *entry,
1081 substring_t *args, int lsm_rule, int audit_type)
1082 {
1083 int result;
1084
1085 if (entry->lsm[lsm_rule].rule)
1086 return -EINVAL;
1087
1088 entry->lsm[lsm_rule].args_p = match_strdup(args);
1089 if (!entry->lsm[lsm_rule].args_p)
1090 return -ENOMEM;
1091
1092 entry->lsm[lsm_rule].type = audit_type;
1093 result = ima_filter_rule_init(entry->lsm[lsm_rule].type, Audit_equal,
1094 entry->lsm[lsm_rule].args_p,
1095 &entry->lsm[lsm_rule].rule);
1096 if (!entry->lsm[lsm_rule].rule) {
1097 pr_warn("rule for LSM \'%s\' is undefined\n",
1098 entry->lsm[lsm_rule].args_p);
1099
1100 if (ima_rules == (struct list_head __rcu *)(&ima_default_rules)) {
1101 kfree(entry->lsm[lsm_rule].args_p);
1102 entry->lsm[lsm_rule].args_p = NULL;
1103 result = -EINVAL;
1104 } else
1105 result = 0;
1106 }
1107
1108 return result;
1109 }
1110
ima_log_string_op(struct audit_buffer * ab,char * key,char * value,enum policy_opt rule_operator)1111 static void ima_log_string_op(struct audit_buffer *ab, char *key, char *value,
1112 enum policy_opt rule_operator)
1113 {
1114 if (!ab)
1115 return;
1116
1117 switch (rule_operator) {
1118 case Opt_uid_gt:
1119 case Opt_euid_gt:
1120 case Opt_gid_gt:
1121 case Opt_egid_gt:
1122 case Opt_fowner_gt:
1123 case Opt_fgroup_gt:
1124 audit_log_format(ab, "%s>", key);
1125 break;
1126 case Opt_uid_lt:
1127 case Opt_euid_lt:
1128 case Opt_gid_lt:
1129 case Opt_egid_lt:
1130 case Opt_fowner_lt:
1131 case Opt_fgroup_lt:
1132 audit_log_format(ab, "%s<", key);
1133 break;
1134 default:
1135 audit_log_format(ab, "%s=", key);
1136 }
1137 audit_log_format(ab, "%s ", value);
1138 }
ima_log_string(struct audit_buffer * ab,char * key,char * value)1139 static void ima_log_string(struct audit_buffer *ab, char *key, char *value)
1140 {
1141 ima_log_string_op(ab, key, value, Opt_err);
1142 }
1143
1144 /*
1145 * Validating the appended signature included in the measurement list requires
1146 * the file hash calculated without the appended signature (i.e., the 'd-modsig'
1147 * field). Therefore, notify the user if they have the 'modsig' field but not
1148 * the 'd-modsig' field in the template.
1149 */
check_template_modsig(const struct ima_template_desc * template)1150 static void check_template_modsig(const struct ima_template_desc *template)
1151 {
1152 #define MSG "template with 'modsig' field also needs 'd-modsig' field\n"
1153 bool has_modsig, has_dmodsig;
1154 static bool checked;
1155 int i;
1156
1157 /* We only need to notify the user once. */
1158 if (checked)
1159 return;
1160
1161 has_modsig = has_dmodsig = false;
1162 for (i = 0; i < template->num_fields; i++) {
1163 if (!strcmp(template->fields[i]->field_id, "modsig"))
1164 has_modsig = true;
1165 else if (!strcmp(template->fields[i]->field_id, "d-modsig"))
1166 has_dmodsig = true;
1167 }
1168
1169 if (has_modsig && !has_dmodsig)
1170 pr_notice(MSG);
1171
1172 checked = true;
1173 #undef MSG
1174 }
1175
ima_validate_rule(struct ima_rule_entry * entry)1176 static bool ima_validate_rule(struct ima_rule_entry *entry)
1177 {
1178 /* Ensure that the action is set and is compatible with the flags */
1179 if (entry->action == UNKNOWN)
1180 return false;
1181
1182 if (entry->action != MEASURE && entry->flags & IMA_PCR)
1183 return false;
1184
1185 if (entry->action != APPRAISE &&
1186 entry->flags & (IMA_DIGSIG_REQUIRED | IMA_MODSIG_ALLOWED |
1187 IMA_CHECK_BLACKLIST | IMA_VALIDATE_ALGOS))
1188 return false;
1189
1190 /*
1191 * The IMA_FUNC bit must be set if and only if there's a valid hook
1192 * function specified, and vice versa. Enforcing this property allows
1193 * for the NONE case below to validate a rule without an explicit hook
1194 * function.
1195 */
1196 if (((entry->flags & IMA_FUNC) && entry->func == NONE) ||
1197 (!(entry->flags & IMA_FUNC) && entry->func != NONE))
1198 return false;
1199
1200 /*
1201 * Ensure that the hook function is compatible with the other
1202 * components of the rule
1203 */
1204 switch (entry->func) {
1205 case NONE:
1206 case FILE_CHECK:
1207 case MMAP_CHECK:
1208 case BPRM_CHECK:
1209 case CREDS_CHECK:
1210 case POST_SETATTR:
1211 case FIRMWARE_CHECK:
1212 case POLICY_CHECK:
1213 if (entry->flags & ~(IMA_FUNC | IMA_MASK | IMA_FSMAGIC |
1214 IMA_UID | IMA_FOWNER | IMA_FSUUID |
1215 IMA_INMASK | IMA_EUID | IMA_PCR |
1216 IMA_FSNAME | IMA_GID | IMA_EGID |
1217 IMA_FGROUP | IMA_DIGSIG_REQUIRED |
1218 IMA_PERMIT_DIRECTIO | IMA_VALIDATE_ALGOS))
1219 return false;
1220
1221 break;
1222 case MODULE_CHECK:
1223 case KEXEC_KERNEL_CHECK:
1224 case KEXEC_INITRAMFS_CHECK:
1225 if (entry->flags & ~(IMA_FUNC | IMA_MASK | IMA_FSMAGIC |
1226 IMA_UID | IMA_FOWNER | IMA_FSUUID |
1227 IMA_INMASK | IMA_EUID | IMA_PCR |
1228 IMA_FSNAME | IMA_GID | IMA_EGID |
1229 IMA_FGROUP | IMA_DIGSIG_REQUIRED |
1230 IMA_PERMIT_DIRECTIO | IMA_MODSIG_ALLOWED |
1231 IMA_CHECK_BLACKLIST | IMA_VALIDATE_ALGOS))
1232 return false;
1233
1234 break;
1235 case KEXEC_CMDLINE:
1236 if (entry->action & ~(MEASURE | DONT_MEASURE))
1237 return false;
1238
1239 if (entry->flags & ~(IMA_FUNC | IMA_FSMAGIC | IMA_UID |
1240 IMA_FOWNER | IMA_FSUUID | IMA_EUID |
1241 IMA_PCR | IMA_FSNAME | IMA_GID | IMA_EGID |
1242 IMA_FGROUP))
1243 return false;
1244
1245 break;
1246 case KEY_CHECK:
1247 if (entry->action & ~(MEASURE | DONT_MEASURE))
1248 return false;
1249
1250 if (entry->flags & ~(IMA_FUNC | IMA_UID | IMA_GID | IMA_PCR |
1251 IMA_KEYRINGS))
1252 return false;
1253
1254 if (ima_rule_contains_lsm_cond(entry))
1255 return false;
1256
1257 break;
1258 case CRITICAL_DATA:
1259 if (entry->action & ~(MEASURE | DONT_MEASURE))
1260 return false;
1261
1262 if (entry->flags & ~(IMA_FUNC | IMA_UID | IMA_GID | IMA_PCR |
1263 IMA_LABEL))
1264 return false;
1265
1266 if (ima_rule_contains_lsm_cond(entry))
1267 return false;
1268
1269 break;
1270 case SETXATTR_CHECK:
1271 /* any action other than APPRAISE is unsupported */
1272 if (entry->action != APPRAISE)
1273 return false;
1274
1275 /* SETXATTR_CHECK requires an appraise_algos parameter */
1276 if (!(entry->flags & IMA_VALIDATE_ALGOS))
1277 return false;
1278
1279 /*
1280 * full policies are not supported, they would have too
1281 * much of a performance impact
1282 */
1283 if (entry->flags & ~(IMA_FUNC | IMA_VALIDATE_ALGOS))
1284 return false;
1285
1286 break;
1287 default:
1288 return false;
1289 }
1290
1291 /* Ensure that combinations of flags are compatible with each other */
1292 if (entry->flags & IMA_CHECK_BLACKLIST &&
1293 !(entry->flags & IMA_MODSIG_ALLOWED))
1294 return false;
1295
1296 return true;
1297 }
1298
ima_parse_appraise_algos(char * arg)1299 static unsigned int ima_parse_appraise_algos(char *arg)
1300 {
1301 unsigned int res = 0;
1302 int idx;
1303 char *token;
1304
1305 while ((token = strsep(&arg, ",")) != NULL) {
1306 idx = match_string(hash_algo_name, HASH_ALGO__LAST, token);
1307
1308 if (idx < 0) {
1309 pr_err("unknown hash algorithm \"%s\"",
1310 token);
1311 return 0;
1312 }
1313
1314 if (!crypto_has_alg(hash_algo_name[idx], 0, 0)) {
1315 pr_err("unavailable hash algorithm \"%s\", check your kernel configuration",
1316 token);
1317 return 0;
1318 }
1319
1320 /* Add the hash algorithm to the 'allowed' bitfield */
1321 res |= (1U << idx);
1322 }
1323
1324 return res;
1325 }
1326
ima_parse_rule(char * rule,struct ima_rule_entry * entry)1327 static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
1328 {
1329 struct audit_buffer *ab;
1330 char *from;
1331 char *p;
1332 bool eid_token; /* either euid or egid */
1333 struct ima_template_desc *template_desc;
1334 int result = 0;
1335
1336 ab = integrity_audit_log_start(audit_context(), GFP_KERNEL,
1337 AUDIT_INTEGRITY_POLICY_RULE);
1338
1339 entry->uid = INVALID_UID;
1340 entry->gid = INVALID_GID;
1341 entry->fowner = INVALID_UID;
1342 entry->fgroup = INVALID_GID;
1343 entry->uid_op = &uid_eq;
1344 entry->gid_op = &gid_eq;
1345 entry->fowner_op = &uid_eq;
1346 entry->fgroup_op = &gid_eq;
1347 entry->action = UNKNOWN;
1348 while ((p = strsep(&rule, " \t")) != NULL) {
1349 substring_t args[MAX_OPT_ARGS];
1350 int token;
1351 unsigned long lnum;
1352
1353 if (result < 0)
1354 break;
1355 if ((*p == '\0') || (*p == ' ') || (*p == '\t'))
1356 continue;
1357 token = match_token(p, policy_tokens, args);
1358 switch (token) {
1359 case Opt_measure:
1360 ima_log_string(ab, "action", "measure");
1361
1362 if (entry->action != UNKNOWN)
1363 result = -EINVAL;
1364
1365 entry->action = MEASURE;
1366 break;
1367 case Opt_dont_measure:
1368 ima_log_string(ab, "action", "dont_measure");
1369
1370 if (entry->action != UNKNOWN)
1371 result = -EINVAL;
1372
1373 entry->action = DONT_MEASURE;
1374 break;
1375 case Opt_appraise:
1376 ima_log_string(ab, "action", "appraise");
1377
1378 if (entry->action != UNKNOWN)
1379 result = -EINVAL;
1380
1381 entry->action = APPRAISE;
1382 break;
1383 case Opt_dont_appraise:
1384 ima_log_string(ab, "action", "dont_appraise");
1385
1386 if (entry->action != UNKNOWN)
1387 result = -EINVAL;
1388
1389 entry->action = DONT_APPRAISE;
1390 break;
1391 case Opt_audit:
1392 ima_log_string(ab, "action", "audit");
1393
1394 if (entry->action != UNKNOWN)
1395 result = -EINVAL;
1396
1397 entry->action = AUDIT;
1398 break;
1399 case Opt_hash:
1400 ima_log_string(ab, "action", "hash");
1401
1402 if (entry->action != UNKNOWN)
1403 result = -EINVAL;
1404
1405 entry->action = HASH;
1406 break;
1407 case Opt_dont_hash:
1408 ima_log_string(ab, "action", "dont_hash");
1409
1410 if (entry->action != UNKNOWN)
1411 result = -EINVAL;
1412
1413 entry->action = DONT_HASH;
1414 break;
1415 case Opt_func:
1416 ima_log_string(ab, "func", args[0].from);
1417
1418 if (entry->func)
1419 result = -EINVAL;
1420
1421 if (strcmp(args[0].from, "FILE_CHECK") == 0)
1422 entry->func = FILE_CHECK;
1423 /* PATH_CHECK is for backwards compat */
1424 else if (strcmp(args[0].from, "PATH_CHECK") == 0)
1425 entry->func = FILE_CHECK;
1426 else if (strcmp(args[0].from, "MODULE_CHECK") == 0)
1427 entry->func = MODULE_CHECK;
1428 else if (strcmp(args[0].from, "FIRMWARE_CHECK") == 0)
1429 entry->func = FIRMWARE_CHECK;
1430 else if ((strcmp(args[0].from, "FILE_MMAP") == 0)
1431 || (strcmp(args[0].from, "MMAP_CHECK") == 0))
1432 entry->func = MMAP_CHECK;
1433 else if (strcmp(args[0].from, "BPRM_CHECK") == 0)
1434 entry->func = BPRM_CHECK;
1435 else if (strcmp(args[0].from, "CREDS_CHECK") == 0)
1436 entry->func = CREDS_CHECK;
1437 else if (strcmp(args[0].from, "KEXEC_KERNEL_CHECK") ==
1438 0)
1439 entry->func = KEXEC_KERNEL_CHECK;
1440 else if (strcmp(args[0].from, "KEXEC_INITRAMFS_CHECK")
1441 == 0)
1442 entry->func = KEXEC_INITRAMFS_CHECK;
1443 else if (strcmp(args[0].from, "POLICY_CHECK") == 0)
1444 entry->func = POLICY_CHECK;
1445 else if (strcmp(args[0].from, "KEXEC_CMDLINE") == 0)
1446 entry->func = KEXEC_CMDLINE;
1447 else if (IS_ENABLED(CONFIG_IMA_MEASURE_ASYMMETRIC_KEYS) &&
1448 strcmp(args[0].from, "KEY_CHECK") == 0)
1449 entry->func = KEY_CHECK;
1450 else if (strcmp(args[0].from, "CRITICAL_DATA") == 0)
1451 entry->func = CRITICAL_DATA;
1452 else if (strcmp(args[0].from, "SETXATTR_CHECK") == 0)
1453 entry->func = SETXATTR_CHECK;
1454 else
1455 result = -EINVAL;
1456 if (!result)
1457 entry->flags |= IMA_FUNC;
1458 break;
1459 case Opt_mask:
1460 ima_log_string(ab, "mask", args[0].from);
1461
1462 if (entry->mask)
1463 result = -EINVAL;
1464
1465 from = args[0].from;
1466 if (*from == '^')
1467 from++;
1468
1469 if ((strcmp(from, "MAY_EXEC")) == 0)
1470 entry->mask = MAY_EXEC;
1471 else if (strcmp(from, "MAY_WRITE") == 0)
1472 entry->mask = MAY_WRITE;
1473 else if (strcmp(from, "MAY_READ") == 0)
1474 entry->mask = MAY_READ;
1475 else if (strcmp(from, "MAY_APPEND") == 0)
1476 entry->mask = MAY_APPEND;
1477 else
1478 result = -EINVAL;
1479 if (!result)
1480 entry->flags |= (*args[0].from == '^')
1481 ? IMA_INMASK : IMA_MASK;
1482 break;
1483 case Opt_fsmagic:
1484 ima_log_string(ab, "fsmagic", args[0].from);
1485
1486 if (entry->fsmagic) {
1487 result = -EINVAL;
1488 break;
1489 }
1490
1491 result = kstrtoul(args[0].from, 16, &entry->fsmagic);
1492 if (!result)
1493 entry->flags |= IMA_FSMAGIC;
1494 break;
1495 case Opt_fsname:
1496 ima_log_string(ab, "fsname", args[0].from);
1497
1498 entry->fsname = kstrdup(args[0].from, GFP_KERNEL);
1499 if (!entry->fsname) {
1500 result = -ENOMEM;
1501 break;
1502 }
1503 result = 0;
1504 entry->flags |= IMA_FSNAME;
1505 break;
1506 case Opt_keyrings:
1507 ima_log_string(ab, "keyrings", args[0].from);
1508
1509 if (!IS_ENABLED(CONFIG_IMA_MEASURE_ASYMMETRIC_KEYS) ||
1510 entry->keyrings) {
1511 result = -EINVAL;
1512 break;
1513 }
1514
1515 entry->keyrings = ima_alloc_rule_opt_list(args);
1516 if (IS_ERR(entry->keyrings)) {
1517 result = PTR_ERR(entry->keyrings);
1518 entry->keyrings = NULL;
1519 break;
1520 }
1521
1522 entry->flags |= IMA_KEYRINGS;
1523 break;
1524 case Opt_label:
1525 ima_log_string(ab, "label", args[0].from);
1526
1527 if (entry->label) {
1528 result = -EINVAL;
1529 break;
1530 }
1531
1532 entry->label = ima_alloc_rule_opt_list(args);
1533 if (IS_ERR(entry->label)) {
1534 result = PTR_ERR(entry->label);
1535 entry->label = NULL;
1536 break;
1537 }
1538
1539 entry->flags |= IMA_LABEL;
1540 break;
1541 case Opt_fsuuid:
1542 ima_log_string(ab, "fsuuid", args[0].from);
1543
1544 if (!uuid_is_null(&entry->fsuuid)) {
1545 result = -EINVAL;
1546 break;
1547 }
1548
1549 result = uuid_parse(args[0].from, &entry->fsuuid);
1550 if (!result)
1551 entry->flags |= IMA_FSUUID;
1552 break;
1553 case Opt_uid_gt:
1554 case Opt_euid_gt:
1555 entry->uid_op = &uid_gt;
1556 fallthrough;
1557 case Opt_uid_lt:
1558 case Opt_euid_lt:
1559 if ((token == Opt_uid_lt) || (token == Opt_euid_lt))
1560 entry->uid_op = &uid_lt;
1561 fallthrough;
1562 case Opt_uid_eq:
1563 case Opt_euid_eq:
1564 eid_token = (token == Opt_euid_eq) ||
1565 (token == Opt_euid_gt) ||
1566 (token == Opt_euid_lt);
1567
1568 ima_log_string_op(ab, eid_token ? "euid" : "uid",
1569 args[0].from, token);
1570
1571 if (uid_valid(entry->uid)) {
1572 result = -EINVAL;
1573 break;
1574 }
1575
1576 result = kstrtoul(args[0].from, 10, &lnum);
1577 if (!result) {
1578 entry->uid = make_kuid(current_user_ns(),
1579 (uid_t) lnum);
1580 if (!uid_valid(entry->uid) ||
1581 (uid_t)lnum != lnum)
1582 result = -EINVAL;
1583 else
1584 entry->flags |= eid_token
1585 ? IMA_EUID : IMA_UID;
1586 }
1587 break;
1588 case Opt_gid_gt:
1589 case Opt_egid_gt:
1590 entry->gid_op = &gid_gt;
1591 fallthrough;
1592 case Opt_gid_lt:
1593 case Opt_egid_lt:
1594 if ((token == Opt_gid_lt) || (token == Opt_egid_lt))
1595 entry->gid_op = &gid_lt;
1596 fallthrough;
1597 case Opt_gid_eq:
1598 case Opt_egid_eq:
1599 eid_token = (token == Opt_egid_eq) ||
1600 (token == Opt_egid_gt) ||
1601 (token == Opt_egid_lt);
1602
1603 ima_log_string_op(ab, eid_token ? "egid" : "gid",
1604 args[0].from, token);
1605
1606 if (gid_valid(entry->gid)) {
1607 result = -EINVAL;
1608 break;
1609 }
1610
1611 result = kstrtoul(args[0].from, 10, &lnum);
1612 if (!result) {
1613 entry->gid = make_kgid(current_user_ns(),
1614 (gid_t)lnum);
1615 if (!gid_valid(entry->gid) ||
1616 (((gid_t)lnum) != lnum))
1617 result = -EINVAL;
1618 else
1619 entry->flags |= eid_token
1620 ? IMA_EGID : IMA_GID;
1621 }
1622 break;
1623 case Opt_fowner_gt:
1624 entry->fowner_op = &uid_gt;
1625 fallthrough;
1626 case Opt_fowner_lt:
1627 if (token == Opt_fowner_lt)
1628 entry->fowner_op = &uid_lt;
1629 fallthrough;
1630 case Opt_fowner_eq:
1631 ima_log_string_op(ab, "fowner", args[0].from, token);
1632
1633 if (uid_valid(entry->fowner)) {
1634 result = -EINVAL;
1635 break;
1636 }
1637
1638 result = kstrtoul(args[0].from, 10, &lnum);
1639 if (!result) {
1640 entry->fowner = make_kuid(current_user_ns(),
1641 (uid_t)lnum);
1642 if (!uid_valid(entry->fowner) ||
1643 (((uid_t)lnum) != lnum))
1644 result = -EINVAL;
1645 else
1646 entry->flags |= IMA_FOWNER;
1647 }
1648 break;
1649 case Opt_fgroup_gt:
1650 entry->fgroup_op = &gid_gt;
1651 fallthrough;
1652 case Opt_fgroup_lt:
1653 if (token == Opt_fgroup_lt)
1654 entry->fgroup_op = &gid_lt;
1655 fallthrough;
1656 case Opt_fgroup_eq:
1657 ima_log_string_op(ab, "fgroup", args[0].from, token);
1658
1659 if (gid_valid(entry->fgroup)) {
1660 result = -EINVAL;
1661 break;
1662 }
1663
1664 result = kstrtoul(args[0].from, 10, &lnum);
1665 if (!result) {
1666 entry->fgroup = make_kgid(current_user_ns(),
1667 (gid_t)lnum);
1668 if (!gid_valid(entry->fgroup) ||
1669 (((gid_t)lnum) != lnum))
1670 result = -EINVAL;
1671 else
1672 entry->flags |= IMA_FGROUP;
1673 }
1674 break;
1675 case Opt_obj_user:
1676 ima_log_string(ab, "obj_user", args[0].from);
1677 result = ima_lsm_rule_init(entry, args,
1678 LSM_OBJ_USER,
1679 AUDIT_OBJ_USER);
1680 break;
1681 case Opt_obj_role:
1682 ima_log_string(ab, "obj_role", args[0].from);
1683 result = ima_lsm_rule_init(entry, args,
1684 LSM_OBJ_ROLE,
1685 AUDIT_OBJ_ROLE);
1686 break;
1687 case Opt_obj_type:
1688 ima_log_string(ab, "obj_type", args[0].from);
1689 result = ima_lsm_rule_init(entry, args,
1690 LSM_OBJ_TYPE,
1691 AUDIT_OBJ_TYPE);
1692 break;
1693 case Opt_subj_user:
1694 ima_log_string(ab, "subj_user", args[0].from);
1695 result = ima_lsm_rule_init(entry, args,
1696 LSM_SUBJ_USER,
1697 AUDIT_SUBJ_USER);
1698 break;
1699 case Opt_subj_role:
1700 ima_log_string(ab, "subj_role", args[0].from);
1701 result = ima_lsm_rule_init(entry, args,
1702 LSM_SUBJ_ROLE,
1703 AUDIT_SUBJ_ROLE);
1704 break;
1705 case Opt_subj_type:
1706 ima_log_string(ab, "subj_type", args[0].from);
1707 result = ima_lsm_rule_init(entry, args,
1708 LSM_SUBJ_TYPE,
1709 AUDIT_SUBJ_TYPE);
1710 break;
1711 case Opt_appraise_type:
1712 ima_log_string(ab, "appraise_type", args[0].from);
1713 if ((strcmp(args[0].from, "imasig")) == 0)
1714 entry->flags |= IMA_DIGSIG_REQUIRED;
1715 else if (IS_ENABLED(CONFIG_IMA_APPRAISE_MODSIG) &&
1716 strcmp(args[0].from, "imasig|modsig") == 0)
1717 entry->flags |= IMA_DIGSIG_REQUIRED |
1718 IMA_MODSIG_ALLOWED;
1719 else
1720 result = -EINVAL;
1721 break;
1722 case Opt_appraise_flag:
1723 ima_log_string(ab, "appraise_flag", args[0].from);
1724 if (IS_ENABLED(CONFIG_IMA_APPRAISE_MODSIG) &&
1725 strstr(args[0].from, "blacklist"))
1726 entry->flags |= IMA_CHECK_BLACKLIST;
1727 else
1728 result = -EINVAL;
1729 break;
1730 case Opt_appraise_algos:
1731 ima_log_string(ab, "appraise_algos", args[0].from);
1732
1733 if (entry->allowed_algos) {
1734 result = -EINVAL;
1735 break;
1736 }
1737
1738 entry->allowed_algos =
1739 ima_parse_appraise_algos(args[0].from);
1740 /* invalid or empty list of algorithms */
1741 if (!entry->allowed_algos) {
1742 result = -EINVAL;
1743 break;
1744 }
1745
1746 entry->flags |= IMA_VALIDATE_ALGOS;
1747
1748 break;
1749 case Opt_permit_directio:
1750 entry->flags |= IMA_PERMIT_DIRECTIO;
1751 break;
1752 case Opt_pcr:
1753 ima_log_string(ab, "pcr", args[0].from);
1754
1755 result = kstrtoint(args[0].from, 10, &entry->pcr);
1756 if (result || INVALID_PCR(entry->pcr))
1757 result = -EINVAL;
1758 else
1759 entry->flags |= IMA_PCR;
1760
1761 break;
1762 case Opt_template:
1763 ima_log_string(ab, "template", args[0].from);
1764 if (entry->action != MEASURE) {
1765 result = -EINVAL;
1766 break;
1767 }
1768 template_desc = lookup_template_desc(args[0].from);
1769 if (!template_desc || entry->template) {
1770 result = -EINVAL;
1771 break;
1772 }
1773
1774 /*
1775 * template_desc_init_fields() does nothing if
1776 * the template is already initialised, so
1777 * it's safe to do this unconditionally
1778 */
1779 template_desc_init_fields(template_desc->fmt,
1780 &(template_desc->fields),
1781 &(template_desc->num_fields));
1782 entry->template = template_desc;
1783 break;
1784 case Opt_err:
1785 ima_log_string(ab, "UNKNOWN", p);
1786 result = -EINVAL;
1787 break;
1788 }
1789 }
1790 if (!result && !ima_validate_rule(entry))
1791 result = -EINVAL;
1792 else if (entry->action == APPRAISE)
1793 temp_ima_appraise |= ima_appraise_flag(entry->func);
1794
1795 if (!result && entry->flags & IMA_MODSIG_ALLOWED) {
1796 template_desc = entry->template ? entry->template :
1797 ima_template_desc_current();
1798 check_template_modsig(template_desc);
1799 }
1800
1801 audit_log_format(ab, "res=%d", !result);
1802 audit_log_end(ab);
1803 return result;
1804 }
1805
1806 /**
1807 * ima_parse_add_rule - add a rule to ima_policy_rules
1808 * @rule - ima measurement policy rule
1809 *
1810 * Avoid locking by allowing just one writer at a time in ima_write_policy()
1811 * Returns the length of the rule parsed, an error code on failure
1812 */
ima_parse_add_rule(char * rule)1813 ssize_t ima_parse_add_rule(char *rule)
1814 {
1815 static const char op[] = "update_policy";
1816 char *p;
1817 struct ima_rule_entry *entry;
1818 ssize_t result, len;
1819 int audit_info = 0;
1820
1821 p = strsep(&rule, "\n");
1822 len = strlen(p) + 1;
1823 p += strspn(p, " \t");
1824
1825 if (*p == '#' || *p == '\0')
1826 return len;
1827
1828 entry = kzalloc(sizeof(*entry), GFP_KERNEL);
1829 if (!entry) {
1830 integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
1831 NULL, op, "-ENOMEM", -ENOMEM, audit_info);
1832 return -ENOMEM;
1833 }
1834
1835 INIT_LIST_HEAD(&entry->list);
1836
1837 result = ima_parse_rule(p, entry);
1838 if (result) {
1839 ima_free_rule(entry);
1840 integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
1841 NULL, op, "invalid-policy", result,
1842 audit_info);
1843 return result;
1844 }
1845
1846 list_add_tail(&entry->list, &ima_temp_rules);
1847
1848 return len;
1849 }
1850
1851 /**
1852 * ima_delete_rules() called to cleanup invalid in-flight policy.
1853 * We don't need locking as we operate on the temp list, which is
1854 * different from the active one. There is also only one user of
1855 * ima_delete_rules() at a time.
1856 */
ima_delete_rules(void)1857 void ima_delete_rules(void)
1858 {
1859 struct ima_rule_entry *entry, *tmp;
1860
1861 temp_ima_appraise = 0;
1862 list_for_each_entry_safe(entry, tmp, &ima_temp_rules, list) {
1863 list_del(&entry->list);
1864 ima_free_rule(entry);
1865 }
1866 }
1867
1868 #define __ima_hook_stringify(func, str) (#func),
1869
1870 const char *const func_tokens[] = {
1871 __ima_hooks(__ima_hook_stringify)
1872 };
1873
1874 #ifdef CONFIG_IMA_READ_POLICY
1875 enum {
1876 mask_exec = 0, mask_write, mask_read, mask_append
1877 };
1878
1879 static const char *const mask_tokens[] = {
1880 "^MAY_EXEC",
1881 "^MAY_WRITE",
1882 "^MAY_READ",
1883 "^MAY_APPEND"
1884 };
1885
ima_policy_start(struct seq_file * m,loff_t * pos)1886 void *ima_policy_start(struct seq_file *m, loff_t *pos)
1887 {
1888 loff_t l = *pos;
1889 struct ima_rule_entry *entry;
1890 struct list_head *ima_rules_tmp;
1891
1892 rcu_read_lock();
1893 ima_rules_tmp = rcu_dereference(ima_rules);
1894 list_for_each_entry_rcu(entry, ima_rules_tmp, list) {
1895 if (!l--) {
1896 rcu_read_unlock();
1897 return entry;
1898 }
1899 }
1900 rcu_read_unlock();
1901 return NULL;
1902 }
1903
ima_policy_next(struct seq_file * m,void * v,loff_t * pos)1904 void *ima_policy_next(struct seq_file *m, void *v, loff_t *pos)
1905 {
1906 struct ima_rule_entry *entry = v;
1907
1908 rcu_read_lock();
1909 entry = list_entry_rcu(entry->list.next, struct ima_rule_entry, list);
1910 rcu_read_unlock();
1911 (*pos)++;
1912
1913 return (&entry->list == &ima_default_rules ||
1914 &entry->list == &ima_policy_rules) ? NULL : entry;
1915 }
1916
ima_policy_stop(struct seq_file * m,void * v)1917 void ima_policy_stop(struct seq_file *m, void *v)
1918 {
1919 }
1920
1921 #define pt(token) policy_tokens[token].pattern
1922 #define mt(token) mask_tokens[token]
1923
1924 /*
1925 * policy_func_show - display the ima_hooks policy rule
1926 */
policy_func_show(struct seq_file * m,enum ima_hooks func)1927 static void policy_func_show(struct seq_file *m, enum ima_hooks func)
1928 {
1929 if (func > 0 && func < MAX_CHECK)
1930 seq_printf(m, "func=%s ", func_tokens[func]);
1931 else
1932 seq_printf(m, "func=%d ", func);
1933 }
1934
ima_show_rule_opt_list(struct seq_file * m,const struct ima_rule_opt_list * opt_list)1935 static void ima_show_rule_opt_list(struct seq_file *m,
1936 const struct ima_rule_opt_list *opt_list)
1937 {
1938 size_t i;
1939
1940 for (i = 0; i < opt_list->count; i++)
1941 seq_printf(m, "%s%s", i ? "|" : "", opt_list->items[i]);
1942 }
1943
ima_policy_show_appraise_algos(struct seq_file * m,unsigned int allowed_hashes)1944 static void ima_policy_show_appraise_algos(struct seq_file *m,
1945 unsigned int allowed_hashes)
1946 {
1947 int idx, list_size = 0;
1948
1949 for (idx = 0; idx < HASH_ALGO__LAST; idx++) {
1950 if (!(allowed_hashes & (1U << idx)))
1951 continue;
1952
1953 /* only add commas if the list contains multiple entries */
1954 if (list_size++)
1955 seq_puts(m, ",");
1956
1957 seq_puts(m, hash_algo_name[idx]);
1958 }
1959 }
1960
ima_policy_show(struct seq_file * m,void * v)1961 int ima_policy_show(struct seq_file *m, void *v)
1962 {
1963 struct ima_rule_entry *entry = v;
1964 int i;
1965 char tbuf[64] = {0,};
1966 int offset = 0;
1967
1968 rcu_read_lock();
1969
1970 if (entry->action & MEASURE)
1971 seq_puts(m, pt(Opt_measure));
1972 if (entry->action & DONT_MEASURE)
1973 seq_puts(m, pt(Opt_dont_measure));
1974 if (entry->action & APPRAISE)
1975 seq_puts(m, pt(Opt_appraise));
1976 if (entry->action & DONT_APPRAISE)
1977 seq_puts(m, pt(Opt_dont_appraise));
1978 if (entry->action & AUDIT)
1979 seq_puts(m, pt(Opt_audit));
1980 if (entry->action & HASH)
1981 seq_puts(m, pt(Opt_hash));
1982 if (entry->action & DONT_HASH)
1983 seq_puts(m, pt(Opt_dont_hash));
1984
1985 seq_puts(m, " ");
1986
1987 if (entry->flags & IMA_FUNC)
1988 policy_func_show(m, entry->func);
1989
1990 if ((entry->flags & IMA_MASK) || (entry->flags & IMA_INMASK)) {
1991 if (entry->flags & IMA_MASK)
1992 offset = 1;
1993 if (entry->mask & MAY_EXEC)
1994 seq_printf(m, pt(Opt_mask), mt(mask_exec) + offset);
1995 if (entry->mask & MAY_WRITE)
1996 seq_printf(m, pt(Opt_mask), mt(mask_write) + offset);
1997 if (entry->mask & MAY_READ)
1998 seq_printf(m, pt(Opt_mask), mt(mask_read) + offset);
1999 if (entry->mask & MAY_APPEND)
2000 seq_printf(m, pt(Opt_mask), mt(mask_append) + offset);
2001 seq_puts(m, " ");
2002 }
2003
2004 if (entry->flags & IMA_FSMAGIC) {
2005 snprintf(tbuf, sizeof(tbuf), "0x%lx", entry->fsmagic);
2006 seq_printf(m, pt(Opt_fsmagic), tbuf);
2007 seq_puts(m, " ");
2008 }
2009
2010 if (entry->flags & IMA_FSNAME) {
2011 snprintf(tbuf, sizeof(tbuf), "%s", entry->fsname);
2012 seq_printf(m, pt(Opt_fsname), tbuf);
2013 seq_puts(m, " ");
2014 }
2015
2016 if (entry->flags & IMA_KEYRINGS) {
2017 seq_puts(m, "keyrings=");
2018 ima_show_rule_opt_list(m, entry->keyrings);
2019 seq_puts(m, " ");
2020 }
2021
2022 if (entry->flags & IMA_LABEL) {
2023 seq_puts(m, "label=");
2024 ima_show_rule_opt_list(m, entry->label);
2025 seq_puts(m, " ");
2026 }
2027
2028 if (entry->flags & IMA_PCR) {
2029 snprintf(tbuf, sizeof(tbuf), "%d", entry->pcr);
2030 seq_printf(m, pt(Opt_pcr), tbuf);
2031 seq_puts(m, " ");
2032 }
2033
2034 if (entry->flags & IMA_FSUUID) {
2035 seq_printf(m, "fsuuid=%pU", &entry->fsuuid);
2036 seq_puts(m, " ");
2037 }
2038
2039 if (entry->flags & IMA_UID) {
2040 snprintf(tbuf, sizeof(tbuf), "%d", __kuid_val(entry->uid));
2041 if (entry->uid_op == &uid_gt)
2042 seq_printf(m, pt(Opt_uid_gt), tbuf);
2043 else if (entry->uid_op == &uid_lt)
2044 seq_printf(m, pt(Opt_uid_lt), tbuf);
2045 else
2046 seq_printf(m, pt(Opt_uid_eq), tbuf);
2047 seq_puts(m, " ");
2048 }
2049
2050 if (entry->flags & IMA_EUID) {
2051 snprintf(tbuf, sizeof(tbuf), "%d", __kuid_val(entry->uid));
2052 if (entry->uid_op == &uid_gt)
2053 seq_printf(m, pt(Opt_euid_gt), tbuf);
2054 else if (entry->uid_op == &uid_lt)
2055 seq_printf(m, pt(Opt_euid_lt), tbuf);
2056 else
2057 seq_printf(m, pt(Opt_euid_eq), tbuf);
2058 seq_puts(m, " ");
2059 }
2060
2061 if (entry->flags & IMA_GID) {
2062 snprintf(tbuf, sizeof(tbuf), "%d", __kgid_val(entry->gid));
2063 if (entry->gid_op == &gid_gt)
2064 seq_printf(m, pt(Opt_gid_gt), tbuf);
2065 else if (entry->gid_op == &gid_lt)
2066 seq_printf(m, pt(Opt_gid_lt), tbuf);
2067 else
2068 seq_printf(m, pt(Opt_gid_eq), tbuf);
2069 seq_puts(m, " ");
2070 }
2071
2072 if (entry->flags & IMA_EGID) {
2073 snprintf(tbuf, sizeof(tbuf), "%d", __kgid_val(entry->gid));
2074 if (entry->gid_op == &gid_gt)
2075 seq_printf(m, pt(Opt_egid_gt), tbuf);
2076 else if (entry->gid_op == &gid_lt)
2077 seq_printf(m, pt(Opt_egid_lt), tbuf);
2078 else
2079 seq_printf(m, pt(Opt_egid_eq), tbuf);
2080 seq_puts(m, " ");
2081 }
2082
2083 if (entry->flags & IMA_FOWNER) {
2084 snprintf(tbuf, sizeof(tbuf), "%d", __kuid_val(entry->fowner));
2085 if (entry->fowner_op == &uid_gt)
2086 seq_printf(m, pt(Opt_fowner_gt), tbuf);
2087 else if (entry->fowner_op == &uid_lt)
2088 seq_printf(m, pt(Opt_fowner_lt), tbuf);
2089 else
2090 seq_printf(m, pt(Opt_fowner_eq), tbuf);
2091 seq_puts(m, " ");
2092 }
2093
2094 if (entry->flags & IMA_FGROUP) {
2095 snprintf(tbuf, sizeof(tbuf), "%d", __kgid_val(entry->fgroup));
2096 if (entry->fgroup_op == &gid_gt)
2097 seq_printf(m, pt(Opt_fgroup_gt), tbuf);
2098 else if (entry->fgroup_op == &gid_lt)
2099 seq_printf(m, pt(Opt_fgroup_lt), tbuf);
2100 else
2101 seq_printf(m, pt(Opt_fgroup_eq), tbuf);
2102 seq_puts(m, " ");
2103 }
2104
2105 if (entry->flags & IMA_VALIDATE_ALGOS) {
2106 seq_puts(m, "appraise_algos=");
2107 ima_policy_show_appraise_algos(m, entry->allowed_algos);
2108 seq_puts(m, " ");
2109 }
2110
2111 for (i = 0; i < MAX_LSM_RULES; i++) {
2112 if (entry->lsm[i].rule) {
2113 switch (i) {
2114 case LSM_OBJ_USER:
2115 seq_printf(m, pt(Opt_obj_user),
2116 entry->lsm[i].args_p);
2117 break;
2118 case LSM_OBJ_ROLE:
2119 seq_printf(m, pt(Opt_obj_role),
2120 entry->lsm[i].args_p);
2121 break;
2122 case LSM_OBJ_TYPE:
2123 seq_printf(m, pt(Opt_obj_type),
2124 entry->lsm[i].args_p);
2125 break;
2126 case LSM_SUBJ_USER:
2127 seq_printf(m, pt(Opt_subj_user),
2128 entry->lsm[i].args_p);
2129 break;
2130 case LSM_SUBJ_ROLE:
2131 seq_printf(m, pt(Opt_subj_role),
2132 entry->lsm[i].args_p);
2133 break;
2134 case LSM_SUBJ_TYPE:
2135 seq_printf(m, pt(Opt_subj_type),
2136 entry->lsm[i].args_p);
2137 break;
2138 }
2139 seq_puts(m, " ");
2140 }
2141 }
2142 if (entry->template)
2143 seq_printf(m, "template=%s ", entry->template->name);
2144 if (entry->flags & IMA_DIGSIG_REQUIRED) {
2145 if (entry->flags & IMA_MODSIG_ALLOWED)
2146 seq_puts(m, "appraise_type=imasig|modsig ");
2147 else
2148 seq_puts(m, "appraise_type=imasig ");
2149 }
2150 if (entry->flags & IMA_CHECK_BLACKLIST)
2151 seq_puts(m, "appraise_flag=check_blacklist ");
2152 if (entry->flags & IMA_PERMIT_DIRECTIO)
2153 seq_puts(m, "permit_directio ");
2154 rcu_read_unlock();
2155 seq_puts(m, "\n");
2156 return 0;
2157 }
2158 #endif /* CONFIG_IMA_READ_POLICY */
2159
2160 #if defined(CONFIG_IMA_APPRAISE) && defined(CONFIG_INTEGRITY_TRUSTED_KEYRING)
2161 /*
2162 * ima_appraise_signature: whether IMA will appraise a given function using
2163 * an IMA digital signature. This is restricted to cases where the kernel
2164 * has a set of built-in trusted keys in order to avoid an attacker simply
2165 * loading additional keys.
2166 */
ima_appraise_signature(enum kernel_read_file_id id)2167 bool ima_appraise_signature(enum kernel_read_file_id id)
2168 {
2169 struct ima_rule_entry *entry;
2170 bool found = false;
2171 enum ima_hooks func;
2172 struct list_head *ima_rules_tmp;
2173
2174 if (id >= READING_MAX_ID)
2175 return false;
2176
2177 func = read_idmap[id] ?: FILE_CHECK;
2178
2179 rcu_read_lock();
2180 ima_rules_tmp = rcu_dereference(ima_rules);
2181 list_for_each_entry_rcu(entry, ima_rules_tmp, list) {
2182 if (entry->action != APPRAISE)
2183 continue;
2184
2185 /*
2186 * A generic entry will match, but otherwise require that it
2187 * match the func we're looking for
2188 */
2189 if (entry->func && entry->func != func)
2190 continue;
2191
2192 /*
2193 * We require this to be a digital signature, not a raw IMA
2194 * hash.
2195 */
2196 if (entry->flags & IMA_DIGSIG_REQUIRED)
2197 found = true;
2198
2199 /*
2200 * We've found a rule that matches, so break now even if it
2201 * didn't require a digital signature - a later rule that does
2202 * won't override it, so would be a false positive.
2203 */
2204 break;
2205 }
2206
2207 rcu_read_unlock();
2208 return found;
2209 }
2210 #endif /* CONFIG_IMA_APPRAISE && CONFIG_INTEGRITY_TRUSTED_KEYRING */
2211