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/seq_file.h>
20 #include <linux/ima.h>
21
22 #include "ima.h"
23
24 /* flags definitions */
25 #define IMA_FUNC 0x0001
26 #define IMA_MASK 0x0002
27 #define IMA_FSMAGIC 0x0004
28 #define IMA_UID 0x0008
29 #define IMA_FOWNER 0x0010
30 #define IMA_FSUUID 0x0020
31 #define IMA_INMASK 0x0040
32 #define IMA_EUID 0x0080
33 #define IMA_PCR 0x0100
34 #define IMA_FSNAME 0x0200
35 #define IMA_KEYRINGS 0x0400
36 #define IMA_LABEL 0x0800
37 #define IMA_VALIDATE_ALGOS 0x1000
38 #define IMA_GID 0x2000
39 #define IMA_EGID 0x4000
40 #define IMA_FGROUP 0x8000
41
42 #define UNKNOWN 0
43 #define MEASURE 0x0001 /* same as IMA_MEASURE */
44 #define DONT_MEASURE 0x0002
45 #define APPRAISE 0x0004 /* same as IMA_APPRAISE */
46 #define DONT_APPRAISE 0x0008
47 #define AUDIT 0x0040
48 #define HASH 0x0100
49 #define DONT_HASH 0x0200
50
51 #define INVALID_PCR(a) (((a) < 0) || \
52 (a) >= (sizeof_field(struct integrity_iint_cache, measured_pcrs) * 8))
53
54 int ima_policy_flag;
55 static int temp_ima_appraise;
56 static int build_ima_appraise __ro_after_init;
57
58 atomic_t ima_setxattr_allowed_hash_algorithms;
59
60 #define MAX_LSM_RULES 6
61 enum lsm_rule_types { LSM_OBJ_USER, LSM_OBJ_ROLE, LSM_OBJ_TYPE,
62 LSM_SUBJ_USER, LSM_SUBJ_ROLE, LSM_SUBJ_TYPE
63 };
64
65 enum policy_types { ORIGINAL_TCB = 1, DEFAULT_TCB };
66
67 enum policy_rule_list { IMA_DEFAULT_POLICY = 1, IMA_CUSTOM_POLICY };
68
69 struct ima_rule_opt_list {
70 size_t count;
71 char *items[];
72 };
73
74 struct ima_rule_entry {
75 struct list_head list;
76 int action;
77 unsigned int flags;
78 enum ima_hooks func;
79 int mask;
80 unsigned long fsmagic;
81 uuid_t fsuuid;
82 kuid_t uid;
83 kgid_t gid;
84 kuid_t fowner;
85 kgid_t fgroup;
86 bool (*uid_op)(kuid_t cred_uid, kuid_t rule_uid); /* Handlers for operators */
87 bool (*gid_op)(kgid_t cred_gid, kgid_t rule_gid);
88 bool (*fowner_op)(kuid_t cred_uid, kuid_t rule_uid); /* uid_eq(), uid_gt(), uid_lt() */
89 bool (*fgroup_op)(kgid_t cred_gid, kgid_t rule_gid); /* gid_eq(), gid_gt(), gid_lt() */
90 int pcr;
91 unsigned int allowed_algos; /* bitfield of allowed hash algorithms */
92 struct {
93 void *rule; /* LSM file metadata specific */
94 char *args_p; /* audit value */
95 int type; /* audit type */
96 } lsm[MAX_LSM_RULES];
97 char *fsname;
98 struct ima_rule_opt_list *keyrings; /* Measure keys added to these keyrings */
99 struct ima_rule_opt_list *label; /* Measure data grouped under this label */
100 struct ima_template_desc *template;
101 };
102
103 /*
104 * sanity check in case the kernels gains more hash algorithms that can
105 * fit in an unsigned int
106 */
107 static_assert(
108 8 * sizeof(unsigned int) >= HASH_ALGO__LAST,
109 "The bitfield allowed_algos in ima_rule_entry is too small to contain all the supported hash algorithms, consider using a bigger type");
110
111 /*
112 * Without LSM specific knowledge, the default policy can only be
113 * written in terms of .action, .func, .mask, .fsmagic, .uid, .gid,
114 * .fowner, and .fgroup
115 */
116
117 /*
118 * The minimum rule set to allow for full TCB coverage. Measures all files
119 * opened or mmap for exec and everything read by root. Dangerous because
120 * normal users can easily run the machine out of memory simply building
121 * and running executables.
122 */
123 static struct ima_rule_entry dont_measure_rules[] __ro_after_init = {
124 {.action = DONT_MEASURE, .fsmagic = PROC_SUPER_MAGIC, .flags = IMA_FSMAGIC},
125 {.action = DONT_MEASURE, .fsmagic = SYSFS_MAGIC, .flags = IMA_FSMAGIC},
126 {.action = DONT_MEASURE, .fsmagic = DEBUGFS_MAGIC, .flags = IMA_FSMAGIC},
127 {.action = DONT_MEASURE, .fsmagic = TMPFS_MAGIC, .flags = IMA_FSMAGIC},
128 {.action = DONT_MEASURE, .fsmagic = DEVPTS_SUPER_MAGIC, .flags = IMA_FSMAGIC},
129 {.action = DONT_MEASURE, .fsmagic = BINFMTFS_MAGIC, .flags = IMA_FSMAGIC},
130 {.action = DONT_MEASURE, .fsmagic = SECURITYFS_MAGIC, .flags = IMA_FSMAGIC},
131 {.action = DONT_MEASURE, .fsmagic = SELINUX_MAGIC, .flags = IMA_FSMAGIC},
132 {.action = DONT_MEASURE, .fsmagic = SMACK_MAGIC, .flags = IMA_FSMAGIC},
133 {.action = DONT_MEASURE, .fsmagic = CGROUP_SUPER_MAGIC,
134 .flags = IMA_FSMAGIC},
135 {.action = DONT_MEASURE, .fsmagic = CGROUP2_SUPER_MAGIC,
136 .flags = IMA_FSMAGIC},
137 {.action = DONT_MEASURE, .fsmagic = NSFS_MAGIC, .flags = IMA_FSMAGIC},
138 {.action = DONT_MEASURE, .fsmagic = EFIVARFS_MAGIC, .flags = IMA_FSMAGIC}
139 };
140
141 static struct ima_rule_entry original_measurement_rules[] __ro_after_init = {
142 {.action = MEASURE, .func = MMAP_CHECK, .mask = MAY_EXEC,
143 .flags = IMA_FUNC | IMA_MASK},
144 {.action = MEASURE, .func = BPRM_CHECK, .mask = MAY_EXEC,
145 .flags = IMA_FUNC | IMA_MASK},
146 {.action = MEASURE, .func = FILE_CHECK, .mask = MAY_READ,
147 .uid = GLOBAL_ROOT_UID, .uid_op = &uid_eq,
148 .flags = IMA_FUNC | IMA_MASK | IMA_UID},
149 {.action = MEASURE, .func = MODULE_CHECK, .flags = IMA_FUNC},
150 {.action = MEASURE, .func = FIRMWARE_CHECK, .flags = IMA_FUNC},
151 };
152
153 static struct ima_rule_entry default_measurement_rules[] __ro_after_init = {
154 {.action = MEASURE, .func = MMAP_CHECK, .mask = MAY_EXEC,
155 .flags = IMA_FUNC | IMA_MASK},
156 {.action = MEASURE, .func = BPRM_CHECK, .mask = MAY_EXEC,
157 .flags = IMA_FUNC | IMA_MASK},
158 {.action = MEASURE, .func = FILE_CHECK, .mask = MAY_READ,
159 .uid = GLOBAL_ROOT_UID, .uid_op = &uid_eq,
160 .flags = IMA_FUNC | IMA_INMASK | IMA_EUID},
161 {.action = MEASURE, .func = FILE_CHECK, .mask = MAY_READ,
162 .uid = GLOBAL_ROOT_UID, .uid_op = &uid_eq,
163 .flags = IMA_FUNC | IMA_INMASK | IMA_UID},
164 {.action = MEASURE, .func = MODULE_CHECK, .flags = IMA_FUNC},
165 {.action = MEASURE, .func = FIRMWARE_CHECK, .flags = IMA_FUNC},
166 {.action = MEASURE, .func = POLICY_CHECK, .flags = IMA_FUNC},
167 };
168
169 static struct ima_rule_entry default_appraise_rules[] __ro_after_init = {
170 {.action = DONT_APPRAISE, .fsmagic = PROC_SUPER_MAGIC, .flags = IMA_FSMAGIC},
171 {.action = DONT_APPRAISE, .fsmagic = SYSFS_MAGIC, .flags = IMA_FSMAGIC},
172 {.action = DONT_APPRAISE, .fsmagic = DEBUGFS_MAGIC, .flags = IMA_FSMAGIC},
173 {.action = DONT_APPRAISE, .fsmagic = TMPFS_MAGIC, .flags = IMA_FSMAGIC},
174 {.action = DONT_APPRAISE, .fsmagic = RAMFS_MAGIC, .flags = IMA_FSMAGIC},
175 {.action = DONT_APPRAISE, .fsmagic = DEVPTS_SUPER_MAGIC, .flags = IMA_FSMAGIC},
176 {.action = DONT_APPRAISE, .fsmagic = BINFMTFS_MAGIC, .flags = IMA_FSMAGIC},
177 {.action = DONT_APPRAISE, .fsmagic = SECURITYFS_MAGIC, .flags = IMA_FSMAGIC},
178 {.action = DONT_APPRAISE, .fsmagic = SELINUX_MAGIC, .flags = IMA_FSMAGIC},
179 {.action = DONT_APPRAISE, .fsmagic = SMACK_MAGIC, .flags = IMA_FSMAGIC},
180 {.action = DONT_APPRAISE, .fsmagic = NSFS_MAGIC, .flags = IMA_FSMAGIC},
181 {.action = DONT_APPRAISE, .fsmagic = EFIVARFS_MAGIC, .flags = IMA_FSMAGIC},
182 {.action = DONT_APPRAISE, .fsmagic = CGROUP_SUPER_MAGIC, .flags = IMA_FSMAGIC},
183 {.action = DONT_APPRAISE, .fsmagic = CGROUP2_SUPER_MAGIC, .flags = IMA_FSMAGIC},
184 #ifdef CONFIG_IMA_WRITE_POLICY
185 {.action = APPRAISE, .func = POLICY_CHECK,
186 .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
187 #endif
188 #ifndef CONFIG_IMA_APPRAISE_SIGNED_INIT
189 {.action = APPRAISE, .fowner = GLOBAL_ROOT_UID, .fowner_op = &uid_eq,
190 .flags = IMA_FOWNER},
191 #else
192 /* force signature */
193 {.action = APPRAISE, .fowner = GLOBAL_ROOT_UID, .fowner_op = &uid_eq,
194 .flags = IMA_FOWNER | IMA_DIGSIG_REQUIRED},
195 #endif
196 };
197
198 static struct ima_rule_entry build_appraise_rules[] __ro_after_init = {
199 #ifdef CONFIG_IMA_APPRAISE_REQUIRE_MODULE_SIGS
200 {.action = APPRAISE, .func = MODULE_CHECK,
201 .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
202 #endif
203 #ifdef CONFIG_IMA_APPRAISE_REQUIRE_FIRMWARE_SIGS
204 {.action = APPRAISE, .func = FIRMWARE_CHECK,
205 .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
206 #endif
207 #ifdef CONFIG_IMA_APPRAISE_REQUIRE_KEXEC_SIGS
208 {.action = APPRAISE, .func = KEXEC_KERNEL_CHECK,
209 .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
210 #endif
211 #ifdef CONFIG_IMA_APPRAISE_REQUIRE_POLICY_SIGS
212 {.action = APPRAISE, .func = POLICY_CHECK,
213 .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
214 #endif
215 };
216
217 static struct ima_rule_entry secure_boot_rules[] __ro_after_init = {
218 {.action = APPRAISE, .func = MODULE_CHECK,
219 .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
220 {.action = APPRAISE, .func = FIRMWARE_CHECK,
221 .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
222 {.action = APPRAISE, .func = KEXEC_KERNEL_CHECK,
223 .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
224 {.action = APPRAISE, .func = POLICY_CHECK,
225 .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
226 };
227
228 static struct ima_rule_entry critical_data_rules[] __ro_after_init = {
229 {.action = MEASURE, .func = CRITICAL_DATA, .flags = IMA_FUNC},
230 };
231
232 /* An array of architecture specific rules */
233 static struct ima_rule_entry *arch_policy_entry __ro_after_init;
234
235 static LIST_HEAD(ima_default_rules);
236 static LIST_HEAD(ima_policy_rules);
237 static LIST_HEAD(ima_temp_rules);
238 static struct list_head __rcu *ima_rules = (struct list_head __rcu *)(&ima_default_rules);
239
240 static int ima_policy __initdata;
241
default_measure_policy_setup(char * str)242 static int __init default_measure_policy_setup(char *str)
243 {
244 if (ima_policy)
245 return 1;
246
247 ima_policy = ORIGINAL_TCB;
248 return 1;
249 }
250 __setup("ima_tcb", default_measure_policy_setup);
251
252 static bool ima_use_appraise_tcb __initdata;
253 static bool ima_use_secure_boot __initdata;
254 static bool ima_use_critical_data __initdata;
255 static bool ima_fail_unverifiable_sigs __ro_after_init;
policy_setup(char * str)256 static int __init policy_setup(char *str)
257 {
258 char *p;
259
260 while ((p = strsep(&str, " |\n")) != NULL) {
261 if (*p == ' ')
262 continue;
263 if ((strcmp(p, "tcb") == 0) && !ima_policy)
264 ima_policy = DEFAULT_TCB;
265 else if (strcmp(p, "appraise_tcb") == 0)
266 ima_use_appraise_tcb = true;
267 else if (strcmp(p, "secure_boot") == 0)
268 ima_use_secure_boot = true;
269 else if (strcmp(p, "critical_data") == 0)
270 ima_use_critical_data = true;
271 else if (strcmp(p, "fail_securely") == 0)
272 ima_fail_unverifiable_sigs = true;
273 else
274 pr_err("policy \"%s\" not found", p);
275 }
276
277 return 1;
278 }
279 __setup("ima_policy=", policy_setup);
280
default_appraise_policy_setup(char * str)281 static int __init default_appraise_policy_setup(char *str)
282 {
283 ima_use_appraise_tcb = true;
284 return 1;
285 }
286 __setup("ima_appraise_tcb", default_appraise_policy_setup);
287
ima_alloc_rule_opt_list(const substring_t * src)288 static struct ima_rule_opt_list *ima_alloc_rule_opt_list(const substring_t *src)
289 {
290 struct ima_rule_opt_list *opt_list;
291 size_t count = 0;
292 char *src_copy;
293 char *cur, *next;
294 size_t i;
295
296 src_copy = match_strdup(src);
297 if (!src_copy)
298 return ERR_PTR(-ENOMEM);
299
300 next = src_copy;
301 while ((cur = strsep(&next, "|"))) {
302 /* Don't accept an empty list item */
303 if (!(*cur)) {
304 kfree(src_copy);
305 return ERR_PTR(-EINVAL);
306 }
307 count++;
308 }
309
310 /* Don't accept an empty list */
311 if (!count) {
312 kfree(src_copy);
313 return ERR_PTR(-EINVAL);
314 }
315
316 opt_list = kzalloc(struct_size(opt_list, items, count), GFP_KERNEL);
317 if (!opt_list) {
318 kfree(src_copy);
319 return ERR_PTR(-ENOMEM);
320 }
321
322 /*
323 * strsep() has already replaced all instances of '|' with '\0',
324 * leaving a byte sequence of NUL-terminated strings. Reference each
325 * string with the array of items.
326 *
327 * IMPORTANT: Ownership of the allocated buffer is transferred from
328 * src_copy to the first element in the items array. To free the
329 * buffer, kfree() must only be called on the first element of the
330 * array.
331 */
332 for (i = 0, cur = src_copy; i < count; i++) {
333 opt_list->items[i] = cur;
334 cur = strchr(cur, '\0') + 1;
335 }
336 opt_list->count = count;
337
338 return opt_list;
339 }
340
ima_free_rule_opt_list(struct ima_rule_opt_list * opt_list)341 static void ima_free_rule_opt_list(struct ima_rule_opt_list *opt_list)
342 {
343 if (!opt_list)
344 return;
345
346 if (opt_list->count) {
347 kfree(opt_list->items[0]);
348 opt_list->count = 0;
349 }
350
351 kfree(opt_list);
352 }
353
ima_lsm_free_rule(struct ima_rule_entry * entry)354 static void ima_lsm_free_rule(struct ima_rule_entry *entry)
355 {
356 int i;
357
358 for (i = 0; i < MAX_LSM_RULES; i++) {
359 ima_filter_rule_free(entry->lsm[i].rule);
360 kfree(entry->lsm[i].args_p);
361 }
362 }
363
ima_free_rule(struct ima_rule_entry * entry)364 static void ima_free_rule(struct ima_rule_entry *entry)
365 {
366 if (!entry)
367 return;
368
369 /*
370 * entry->template->fields may be allocated in ima_parse_rule() but that
371 * reference is owned by the corresponding ima_template_desc element in
372 * the defined_templates list and cannot be freed here
373 */
374 kfree(entry->fsname);
375 ima_free_rule_opt_list(entry->keyrings);
376 ima_lsm_free_rule(entry);
377 kfree(entry);
378 }
379
ima_lsm_copy_rule(struct ima_rule_entry * entry)380 static struct ima_rule_entry *ima_lsm_copy_rule(struct ima_rule_entry *entry)
381 {
382 struct ima_rule_entry *nentry;
383 int i;
384
385 /*
386 * Immutable elements are copied over as pointers and data; only
387 * lsm rules can change
388 */
389 nentry = kmemdup(entry, sizeof(*nentry), GFP_KERNEL);
390 if (!nentry)
391 return NULL;
392
393 memset(nentry->lsm, 0, sizeof_field(struct ima_rule_entry, lsm));
394
395 for (i = 0; i < MAX_LSM_RULES; i++) {
396 if (!entry->lsm[i].args_p)
397 continue;
398
399 nentry->lsm[i].type = entry->lsm[i].type;
400 nentry->lsm[i].args_p = entry->lsm[i].args_p;
401
402 ima_filter_rule_init(nentry->lsm[i].type, Audit_equal,
403 nentry->lsm[i].args_p,
404 &nentry->lsm[i].rule);
405 if (!nentry->lsm[i].rule)
406 pr_warn("rule for LSM \'%s\' is undefined\n",
407 nentry->lsm[i].args_p);
408 }
409 return nentry;
410 }
411
ima_lsm_update_rule(struct ima_rule_entry * entry)412 static int ima_lsm_update_rule(struct ima_rule_entry *entry)
413 {
414 int i;
415 struct ima_rule_entry *nentry;
416
417 nentry = ima_lsm_copy_rule(entry);
418 if (!nentry)
419 return -ENOMEM;
420
421 list_replace_rcu(&entry->list, &nentry->list);
422 synchronize_rcu();
423 /*
424 * ima_lsm_copy_rule() shallow copied all references, except for the
425 * LSM references, from entry to nentry so we only want to free the LSM
426 * references and the entry itself. All other memory references will now
427 * be owned by nentry.
428 */
429 for (i = 0; i < MAX_LSM_RULES; i++)
430 ima_filter_rule_free(entry->lsm[i].rule);
431 kfree(entry);
432
433 return 0;
434 }
435
ima_rule_contains_lsm_cond(struct ima_rule_entry * entry)436 static bool ima_rule_contains_lsm_cond(struct ima_rule_entry *entry)
437 {
438 int i;
439
440 for (i = 0; i < MAX_LSM_RULES; i++)
441 if (entry->lsm[i].args_p)
442 return true;
443
444 return false;
445 }
446
447 /*
448 * The LSM policy can be reloaded, leaving the IMA LSM based rules referring
449 * to the old, stale LSM policy. Update the IMA LSM based rules to reflect
450 * the reloaded LSM policy.
451 */
ima_lsm_update_rules(void)452 static void ima_lsm_update_rules(void)
453 {
454 struct ima_rule_entry *entry, *e;
455 int result;
456
457 list_for_each_entry_safe(entry, e, &ima_policy_rules, list) {
458 if (!ima_rule_contains_lsm_cond(entry))
459 continue;
460
461 result = ima_lsm_update_rule(entry);
462 if (result) {
463 pr_err("lsm rule update error %d\n", result);
464 return;
465 }
466 }
467 }
468
ima_lsm_policy_change(struct notifier_block * nb,unsigned long event,void * lsm_data)469 int ima_lsm_policy_change(struct notifier_block *nb, unsigned long event,
470 void *lsm_data)
471 {
472 if (event != LSM_POLICY_CHANGE)
473 return NOTIFY_DONE;
474
475 ima_lsm_update_rules();
476 return NOTIFY_OK;
477 }
478
479 /**
480 * ima_match_rule_data - determine whether func_data matches the policy rule
481 * @rule: a pointer to a rule
482 * @func_data: data to match against the measure rule data
483 * @cred: a pointer to a credentials structure for user validation
484 *
485 * Returns true if func_data matches one in the rule, false otherwise.
486 */
ima_match_rule_data(struct ima_rule_entry * rule,const char * func_data,const struct cred * cred)487 static bool ima_match_rule_data(struct ima_rule_entry *rule,
488 const char *func_data,
489 const struct cred *cred)
490 {
491 const struct ima_rule_opt_list *opt_list = NULL;
492 bool matched = false;
493 size_t i;
494
495 if ((rule->flags & IMA_UID) && !rule->uid_op(cred->uid, rule->uid))
496 return false;
497
498 switch (rule->func) {
499 case KEY_CHECK:
500 if (!rule->keyrings)
501 return true;
502
503 opt_list = rule->keyrings;
504 break;
505 case CRITICAL_DATA:
506 if (!rule->label)
507 return true;
508
509 opt_list = rule->label;
510 break;
511 default:
512 return false;
513 }
514
515 if (!func_data)
516 return false;
517
518 for (i = 0; i < opt_list->count; i++) {
519 if (!strcmp(opt_list->items[i], func_data)) {
520 matched = true;
521 break;
522 }
523 }
524
525 return matched;
526 }
527
528 /**
529 * ima_match_rules - determine whether an inode matches the policy rule.
530 * @rule: a pointer to a rule
531 * @mnt_userns: user namespace of the mount the inode was found from
532 * @inode: a pointer to an inode
533 * @cred: a pointer to a credentials structure for user validation
534 * @secid: the secid of the task to be validated
535 * @func: LIM hook identifier
536 * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC)
537 * @func_data: func specific data, may be NULL
538 *
539 * Returns true on rule match, false on failure.
540 */
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)541 static bool ima_match_rules(struct ima_rule_entry *rule,
542 struct user_namespace *mnt_userns,
543 struct inode *inode, const struct cred *cred,
544 u32 secid, enum ima_hooks func, int mask,
545 const char *func_data)
546 {
547 int i;
548 bool result = false;
549 struct ima_rule_entry *lsm_rule = rule;
550 bool rule_reinitialized = false;
551
552 if ((rule->flags & IMA_FUNC) &&
553 (rule->func != func && func != POST_SETATTR))
554 return false;
555
556 switch (func) {
557 case KEY_CHECK:
558 case CRITICAL_DATA:
559 return ((rule->func == func) &&
560 ima_match_rule_data(rule, func_data, cred));
561 default:
562 break;
563 }
564
565 if ((rule->flags & IMA_MASK) &&
566 (rule->mask != mask && func != POST_SETATTR))
567 return false;
568 if ((rule->flags & IMA_INMASK) &&
569 (!(rule->mask & mask) && func != POST_SETATTR))
570 return false;
571 if ((rule->flags & IMA_FSMAGIC)
572 && rule->fsmagic != inode->i_sb->s_magic)
573 return false;
574 if ((rule->flags & IMA_FSNAME)
575 && strcmp(rule->fsname, inode->i_sb->s_type->name))
576 return false;
577 if ((rule->flags & IMA_FSUUID) &&
578 !uuid_equal(&rule->fsuuid, &inode->i_sb->s_uuid))
579 return false;
580 if ((rule->flags & IMA_UID) && !rule->uid_op(cred->uid, rule->uid))
581 return false;
582 if (rule->flags & IMA_EUID) {
583 if (has_capability_noaudit(current, CAP_SETUID)) {
584 if (!rule->uid_op(cred->euid, rule->uid)
585 && !rule->uid_op(cred->suid, rule->uid)
586 && !rule->uid_op(cred->uid, rule->uid))
587 return false;
588 } else if (!rule->uid_op(cred->euid, rule->uid))
589 return false;
590 }
591 if ((rule->flags & IMA_GID) && !rule->gid_op(cred->gid, rule->gid))
592 return false;
593 if (rule->flags & IMA_EGID) {
594 if (has_capability_noaudit(current, CAP_SETGID)) {
595 if (!rule->gid_op(cred->egid, rule->gid)
596 && !rule->gid_op(cred->sgid, rule->gid)
597 && !rule->gid_op(cred->gid, rule->gid))
598 return false;
599 } else if (!rule->gid_op(cred->egid, rule->gid))
600 return false;
601 }
602 if ((rule->flags & IMA_FOWNER) &&
603 !rule->fowner_op(i_uid_into_mnt(mnt_userns, inode), rule->fowner))
604 return false;
605 if ((rule->flags & IMA_FGROUP) &&
606 !rule->fgroup_op(i_gid_into_mnt(mnt_userns, inode), rule->fgroup))
607 return false;
608 for (i = 0; i < MAX_LSM_RULES; i++) {
609 int rc = 0;
610 u32 osid;
611
612 if (!lsm_rule->lsm[i].rule) {
613 if (!lsm_rule->lsm[i].args_p)
614 continue;
615 else
616 return false;
617 }
618
619 retry:
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, lsm_rule->lsm[i].type,
626 Audit_equal,
627 lsm_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, lsm_rule->lsm[i].type,
633 Audit_equal,
634 lsm_rule->lsm[i].rule);
635 break;
636 default:
637 break;
638 }
639
640 if (rc == -ESTALE && !rule_reinitialized) {
641 lsm_rule = ima_lsm_copy_rule(rule);
642 if (lsm_rule) {
643 rule_reinitialized = true;
644 goto retry;
645 }
646 }
647 if (!rc) {
648 result = false;
649 goto out;
650 }
651 }
652 result = true;
653
654 out:
655 if (rule_reinitialized) {
656 for (i = 0; i < MAX_LSM_RULES; i++)
657 ima_filter_rule_free(lsm_rule->lsm[i].rule);
658 kfree(lsm_rule);
659 }
660 return result;
661 }
662
663 /*
664 * In addition to knowing that we need to appraise the file in general,
665 * we need to differentiate between calling hooks, for hook specific rules.
666 */
get_subaction(struct ima_rule_entry * rule,enum ima_hooks func)667 static int get_subaction(struct ima_rule_entry *rule, enum ima_hooks func)
668 {
669 if (!(rule->flags & IMA_FUNC))
670 return IMA_FILE_APPRAISE;
671
672 switch (func) {
673 case MMAP_CHECK:
674 return IMA_MMAP_APPRAISE;
675 case BPRM_CHECK:
676 return IMA_BPRM_APPRAISE;
677 case CREDS_CHECK:
678 return IMA_CREDS_APPRAISE;
679 case FILE_CHECK:
680 case POST_SETATTR:
681 return IMA_FILE_APPRAISE;
682 case MODULE_CHECK ... MAX_CHECK - 1:
683 default:
684 return IMA_READ_APPRAISE;
685 }
686 }
687
688 /**
689 * ima_match_policy - decision based on LSM and other conditions
690 * @mnt_userns: user namespace of the mount the inode was found from
691 * @inode: pointer to an inode for which the policy decision is being made
692 * @cred: pointer to a credentials structure for which the policy decision is
693 * being made
694 * @secid: LSM secid of the task to be validated
695 * @func: IMA hook identifier
696 * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC)
697 * @flags: IMA actions to consider (e.g. IMA_MEASURE | IMA_APPRAISE)
698 * @pcr: set the pcr to extend
699 * @template_desc: the template that should be used for this rule
700 * @func_data: func specific data, may be NULL
701 * @allowed_algos: allowlist of hash algorithms for the IMA xattr
702 *
703 * Measure decision based on func/mask/fsmagic and LSM(subj/obj/type)
704 * conditions.
705 *
706 * Since the IMA policy may be updated multiple times we need to lock the
707 * list when walking it. Reads are many orders of magnitude more numerous
708 * than writes so ima_match_policy() is classical RCU candidate.
709 */
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)710 int ima_match_policy(struct user_namespace *mnt_userns, struct inode *inode,
711 const struct cred *cred, u32 secid, enum ima_hooks func,
712 int mask, int flags, int *pcr,
713 struct ima_template_desc **template_desc,
714 const char *func_data, unsigned int *allowed_algos)
715 {
716 struct ima_rule_entry *entry;
717 int action = 0, actmask = flags | (flags << 1);
718 struct list_head *ima_rules_tmp;
719
720 if (template_desc && !*template_desc)
721 *template_desc = ima_template_desc_current();
722
723 rcu_read_lock();
724 ima_rules_tmp = rcu_dereference(ima_rules);
725 list_for_each_entry_rcu(entry, ima_rules_tmp, list) {
726
727 if (!(entry->action & actmask))
728 continue;
729
730 if (!ima_match_rules(entry, mnt_userns, inode, cred, secid,
731 func, mask, func_data))
732 continue;
733
734 action |= entry->flags & IMA_NONACTION_FLAGS;
735
736 action |= entry->action & IMA_DO_MASK;
737 if (entry->action & IMA_APPRAISE) {
738 action |= get_subaction(entry, func);
739 action &= ~IMA_HASH;
740 if (ima_fail_unverifiable_sigs)
741 action |= IMA_FAIL_UNVERIFIABLE_SIGS;
742
743 if (allowed_algos &&
744 entry->flags & IMA_VALIDATE_ALGOS)
745 *allowed_algos = entry->allowed_algos;
746 }
747
748 if (entry->action & IMA_DO_MASK)
749 actmask &= ~(entry->action | entry->action << 1);
750 else
751 actmask &= ~(entry->action | entry->action >> 1);
752
753 if ((pcr) && (entry->flags & IMA_PCR))
754 *pcr = entry->pcr;
755
756 if (template_desc && entry->template)
757 *template_desc = entry->template;
758
759 if (!actmask)
760 break;
761 }
762 rcu_read_unlock();
763
764 return action;
765 }
766
767 /**
768 * ima_update_policy_flags() - Update global IMA variables
769 *
770 * Update ima_policy_flag and ima_setxattr_allowed_hash_algorithms
771 * based on the currently loaded policy.
772 *
773 * With ima_policy_flag, the decision to short circuit out of a function
774 * or not call the function in the first place can be made earlier.
775 *
776 * With ima_setxattr_allowed_hash_algorithms, the policy can restrict the
777 * set of hash algorithms accepted when updating the security.ima xattr of
778 * a file.
779 *
780 * Context: called after a policy update and at system initialization.
781 */
ima_update_policy_flags(void)782 void ima_update_policy_flags(void)
783 {
784 struct ima_rule_entry *entry;
785 int new_policy_flag = 0;
786 struct list_head *ima_rules_tmp;
787
788 rcu_read_lock();
789 ima_rules_tmp = rcu_dereference(ima_rules);
790 list_for_each_entry_rcu(entry, ima_rules_tmp, list) {
791 /*
792 * SETXATTR_CHECK rules do not implement a full policy check
793 * because rule checking would probably have an important
794 * performance impact on setxattr(). As a consequence, only one
795 * SETXATTR_CHECK can be active at a given time.
796 * Because we want to preserve that property, we set out to use
797 * atomic_cmpxchg. Either:
798 * - the atomic was non-zero: a setxattr hash policy is
799 * already enforced, we do nothing
800 * - the atomic was zero: no setxattr policy was set, enable
801 * the setxattr hash policy
802 */
803 if (entry->func == SETXATTR_CHECK) {
804 atomic_cmpxchg(&ima_setxattr_allowed_hash_algorithms,
805 0, entry->allowed_algos);
806 /* SETXATTR_CHECK doesn't impact ima_policy_flag */
807 continue;
808 }
809
810 if (entry->action & IMA_DO_MASK)
811 new_policy_flag |= entry->action;
812 }
813 rcu_read_unlock();
814
815 ima_appraise |= (build_ima_appraise | temp_ima_appraise);
816 if (!ima_appraise)
817 new_policy_flag &= ~IMA_APPRAISE;
818
819 ima_policy_flag = new_policy_flag;
820 }
821
ima_appraise_flag(enum ima_hooks func)822 static int ima_appraise_flag(enum ima_hooks func)
823 {
824 if (func == MODULE_CHECK)
825 return IMA_APPRAISE_MODULES;
826 else if (func == FIRMWARE_CHECK)
827 return IMA_APPRAISE_FIRMWARE;
828 else if (func == POLICY_CHECK)
829 return IMA_APPRAISE_POLICY;
830 else if (func == KEXEC_KERNEL_CHECK)
831 return IMA_APPRAISE_KEXEC;
832 return 0;
833 }
834
add_rules(struct ima_rule_entry * entries,int count,enum policy_rule_list policy_rule)835 static void add_rules(struct ima_rule_entry *entries, int count,
836 enum policy_rule_list policy_rule)
837 {
838 int i = 0;
839
840 for (i = 0; i < count; i++) {
841 struct ima_rule_entry *entry;
842
843 if (policy_rule & IMA_DEFAULT_POLICY)
844 list_add_tail(&entries[i].list, &ima_default_rules);
845
846 if (policy_rule & IMA_CUSTOM_POLICY) {
847 entry = kmemdup(&entries[i], sizeof(*entry),
848 GFP_KERNEL);
849 if (!entry)
850 continue;
851
852 list_add_tail(&entry->list, &ima_policy_rules);
853 }
854 if (entries[i].action == APPRAISE) {
855 if (entries != build_appraise_rules)
856 temp_ima_appraise |=
857 ima_appraise_flag(entries[i].func);
858 else
859 build_ima_appraise |=
860 ima_appraise_flag(entries[i].func);
861 }
862 }
863 }
864
865 static int ima_parse_rule(char *rule, struct ima_rule_entry *entry);
866
ima_init_arch_policy(void)867 static int __init ima_init_arch_policy(void)
868 {
869 const char * const *arch_rules;
870 const char * const *rules;
871 int arch_entries = 0;
872 int i = 0;
873
874 arch_rules = arch_get_ima_policy();
875 if (!arch_rules)
876 return arch_entries;
877
878 /* Get number of rules */
879 for (rules = arch_rules; *rules != NULL; rules++)
880 arch_entries++;
881
882 arch_policy_entry = kcalloc(arch_entries + 1,
883 sizeof(*arch_policy_entry), GFP_KERNEL);
884 if (!arch_policy_entry)
885 return 0;
886
887 /* Convert each policy string rules to struct ima_rule_entry format */
888 for (rules = arch_rules, i = 0; *rules != NULL; rules++) {
889 char rule[255];
890 int result;
891
892 result = strscpy(rule, *rules, sizeof(rule));
893
894 INIT_LIST_HEAD(&arch_policy_entry[i].list);
895 result = ima_parse_rule(rule, &arch_policy_entry[i]);
896 if (result) {
897 pr_warn("Skipping unknown architecture policy rule: %s\n",
898 rule);
899 memset(&arch_policy_entry[i], 0,
900 sizeof(*arch_policy_entry));
901 continue;
902 }
903 i++;
904 }
905 return i;
906 }
907
908 /**
909 * ima_init_policy - initialize the default measure rules.
910 *
911 * ima_rules points to either the ima_default_rules or the new ima_policy_rules.
912 */
ima_init_policy(void)913 void __init ima_init_policy(void)
914 {
915 int build_appraise_entries, arch_entries;
916
917 /* if !ima_policy, we load NO default rules */
918 if (ima_policy)
919 add_rules(dont_measure_rules, ARRAY_SIZE(dont_measure_rules),
920 IMA_DEFAULT_POLICY);
921
922 switch (ima_policy) {
923 case ORIGINAL_TCB:
924 add_rules(original_measurement_rules,
925 ARRAY_SIZE(original_measurement_rules),
926 IMA_DEFAULT_POLICY);
927 break;
928 case DEFAULT_TCB:
929 add_rules(default_measurement_rules,
930 ARRAY_SIZE(default_measurement_rules),
931 IMA_DEFAULT_POLICY);
932 break;
933 default:
934 break;
935 }
936
937 /*
938 * Based on runtime secure boot flags, insert arch specific measurement
939 * and appraise rules requiring file signatures for both the initial
940 * and custom policies, prior to other appraise rules.
941 * (Highest priority)
942 */
943 arch_entries = ima_init_arch_policy();
944 if (!arch_entries)
945 pr_info("No architecture policies found\n");
946 else
947 add_rules(arch_policy_entry, arch_entries,
948 IMA_DEFAULT_POLICY | IMA_CUSTOM_POLICY);
949
950 /*
951 * Insert the builtin "secure_boot" policy rules requiring file
952 * signatures, prior to other appraise rules.
953 */
954 if (ima_use_secure_boot)
955 add_rules(secure_boot_rules, ARRAY_SIZE(secure_boot_rules),
956 IMA_DEFAULT_POLICY);
957
958 /*
959 * Insert the build time appraise rules requiring file signatures
960 * for both the initial and custom policies, prior to other appraise
961 * rules. As the secure boot rules includes all of the build time
962 * rules, include either one or the other set of rules, but not both.
963 */
964 build_appraise_entries = ARRAY_SIZE(build_appraise_rules);
965 if (build_appraise_entries) {
966 if (ima_use_secure_boot)
967 add_rules(build_appraise_rules, build_appraise_entries,
968 IMA_CUSTOM_POLICY);
969 else
970 add_rules(build_appraise_rules, build_appraise_entries,
971 IMA_DEFAULT_POLICY | IMA_CUSTOM_POLICY);
972 }
973
974 if (ima_use_appraise_tcb)
975 add_rules(default_appraise_rules,
976 ARRAY_SIZE(default_appraise_rules),
977 IMA_DEFAULT_POLICY);
978
979 if (ima_use_critical_data)
980 add_rules(critical_data_rules,
981 ARRAY_SIZE(critical_data_rules),
982 IMA_DEFAULT_POLICY);
983
984 atomic_set(&ima_setxattr_allowed_hash_algorithms, 0);
985
986 ima_update_policy_flags();
987 }
988
989 /* Make sure we have a valid policy, at least containing some rules. */
ima_check_policy(void)990 int ima_check_policy(void)
991 {
992 if (list_empty(&ima_temp_rules))
993 return -EINVAL;
994 return 0;
995 }
996
997 /**
998 * ima_update_policy - update default_rules with new measure rules
999 *
1000 * Called on file .release to update the default rules with a complete new
1001 * policy. What we do here is to splice ima_policy_rules and ima_temp_rules so
1002 * they make a queue. The policy may be updated multiple times and this is the
1003 * RCU updater.
1004 *
1005 * Policy rules are never deleted so ima_policy_flag gets zeroed only once when
1006 * we switch from the default policy to user defined.
1007 */
ima_update_policy(void)1008 void ima_update_policy(void)
1009 {
1010 struct list_head *policy = &ima_policy_rules;
1011
1012 list_splice_tail_init_rcu(&ima_temp_rules, policy, synchronize_rcu);
1013
1014 if (ima_rules != (struct list_head __rcu *)policy) {
1015 ima_policy_flag = 0;
1016
1017 rcu_assign_pointer(ima_rules, policy);
1018 /*
1019 * IMA architecture specific policy rules are specified
1020 * as strings and converted to an array of ima_entry_rules
1021 * on boot. After loading a custom policy, free the
1022 * architecture specific rules stored as an array.
1023 */
1024 kfree(arch_policy_entry);
1025 }
1026 ima_update_policy_flags();
1027
1028 /* Custom IMA policy has been loaded */
1029 ima_process_queued_keys();
1030 }
1031
1032 /* Keep the enumeration in sync with the policy_tokens! */
1033 enum policy_opt {
1034 Opt_measure, Opt_dont_measure,
1035 Opt_appraise, Opt_dont_appraise,
1036 Opt_audit, Opt_hash, Opt_dont_hash,
1037 Opt_obj_user, Opt_obj_role, Opt_obj_type,
1038 Opt_subj_user, Opt_subj_role, Opt_subj_type,
1039 Opt_func, Opt_mask, Opt_fsmagic, Opt_fsname, Opt_fsuuid,
1040 Opt_uid_eq, Opt_euid_eq, Opt_gid_eq, Opt_egid_eq,
1041 Opt_fowner_eq, Opt_fgroup_eq,
1042 Opt_uid_gt, Opt_euid_gt, Opt_gid_gt, Opt_egid_gt,
1043 Opt_fowner_gt, Opt_fgroup_gt,
1044 Opt_uid_lt, Opt_euid_lt, Opt_gid_lt, Opt_egid_lt,
1045 Opt_fowner_lt, Opt_fgroup_lt,
1046 Opt_digest_type,
1047 Opt_appraise_type, Opt_appraise_flag, Opt_appraise_algos,
1048 Opt_permit_directio, Opt_pcr, Opt_template, Opt_keyrings,
1049 Opt_label, Opt_err
1050 };
1051
1052 static const match_table_t policy_tokens = {
1053 {Opt_measure, "measure"},
1054 {Opt_dont_measure, "dont_measure"},
1055 {Opt_appraise, "appraise"},
1056 {Opt_dont_appraise, "dont_appraise"},
1057 {Opt_audit, "audit"},
1058 {Opt_hash, "hash"},
1059 {Opt_dont_hash, "dont_hash"},
1060 {Opt_obj_user, "obj_user=%s"},
1061 {Opt_obj_role, "obj_role=%s"},
1062 {Opt_obj_type, "obj_type=%s"},
1063 {Opt_subj_user, "subj_user=%s"},
1064 {Opt_subj_role, "subj_role=%s"},
1065 {Opt_subj_type, "subj_type=%s"},
1066 {Opt_func, "func=%s"},
1067 {Opt_mask, "mask=%s"},
1068 {Opt_fsmagic, "fsmagic=%s"},
1069 {Opt_fsname, "fsname=%s"},
1070 {Opt_fsuuid, "fsuuid=%s"},
1071 {Opt_uid_eq, "uid=%s"},
1072 {Opt_euid_eq, "euid=%s"},
1073 {Opt_gid_eq, "gid=%s"},
1074 {Opt_egid_eq, "egid=%s"},
1075 {Opt_fowner_eq, "fowner=%s"},
1076 {Opt_fgroup_eq, "fgroup=%s"},
1077 {Opt_uid_gt, "uid>%s"},
1078 {Opt_euid_gt, "euid>%s"},
1079 {Opt_gid_gt, "gid>%s"},
1080 {Opt_egid_gt, "egid>%s"},
1081 {Opt_fowner_gt, "fowner>%s"},
1082 {Opt_fgroup_gt, "fgroup>%s"},
1083 {Opt_uid_lt, "uid<%s"},
1084 {Opt_euid_lt, "euid<%s"},
1085 {Opt_gid_lt, "gid<%s"},
1086 {Opt_egid_lt, "egid<%s"},
1087 {Opt_fowner_lt, "fowner<%s"},
1088 {Opt_fgroup_lt, "fgroup<%s"},
1089 {Opt_digest_type, "digest_type=%s"},
1090 {Opt_appraise_type, "appraise_type=%s"},
1091 {Opt_appraise_flag, "appraise_flag=%s"},
1092 {Opt_appraise_algos, "appraise_algos=%s"},
1093 {Opt_permit_directio, "permit_directio"},
1094 {Opt_pcr, "pcr=%s"},
1095 {Opt_template, "template=%s"},
1096 {Opt_keyrings, "keyrings=%s"},
1097 {Opt_label, "label=%s"},
1098 {Opt_err, NULL}
1099 };
1100
ima_lsm_rule_init(struct ima_rule_entry * entry,substring_t * args,int lsm_rule,int audit_type)1101 static int ima_lsm_rule_init(struct ima_rule_entry *entry,
1102 substring_t *args, int lsm_rule, int audit_type)
1103 {
1104 int result;
1105
1106 if (entry->lsm[lsm_rule].rule)
1107 return -EINVAL;
1108
1109 entry->lsm[lsm_rule].args_p = match_strdup(args);
1110 if (!entry->lsm[lsm_rule].args_p)
1111 return -ENOMEM;
1112
1113 entry->lsm[lsm_rule].type = audit_type;
1114 result = ima_filter_rule_init(entry->lsm[lsm_rule].type, Audit_equal,
1115 entry->lsm[lsm_rule].args_p,
1116 &entry->lsm[lsm_rule].rule);
1117 if (!entry->lsm[lsm_rule].rule) {
1118 pr_warn("rule for LSM \'%s\' is undefined\n",
1119 entry->lsm[lsm_rule].args_p);
1120
1121 if (ima_rules == (struct list_head __rcu *)(&ima_default_rules)) {
1122 kfree(entry->lsm[lsm_rule].args_p);
1123 entry->lsm[lsm_rule].args_p = NULL;
1124 result = -EINVAL;
1125 } else
1126 result = 0;
1127 }
1128
1129 return result;
1130 }
1131
ima_log_string_op(struct audit_buffer * ab,char * key,char * value,enum policy_opt rule_operator)1132 static void ima_log_string_op(struct audit_buffer *ab, char *key, char *value,
1133 enum policy_opt rule_operator)
1134 {
1135 if (!ab)
1136 return;
1137
1138 switch (rule_operator) {
1139 case Opt_uid_gt:
1140 case Opt_euid_gt:
1141 case Opt_gid_gt:
1142 case Opt_egid_gt:
1143 case Opt_fowner_gt:
1144 case Opt_fgroup_gt:
1145 audit_log_format(ab, "%s>", key);
1146 break;
1147 case Opt_uid_lt:
1148 case Opt_euid_lt:
1149 case Opt_gid_lt:
1150 case Opt_egid_lt:
1151 case Opt_fowner_lt:
1152 case Opt_fgroup_lt:
1153 audit_log_format(ab, "%s<", key);
1154 break;
1155 default:
1156 audit_log_format(ab, "%s=", key);
1157 }
1158 audit_log_format(ab, "%s ", value);
1159 }
ima_log_string(struct audit_buffer * ab,char * key,char * value)1160 static void ima_log_string(struct audit_buffer *ab, char *key, char *value)
1161 {
1162 ima_log_string_op(ab, key, value, Opt_err);
1163 }
1164
1165 /*
1166 * Validating the appended signature included in the measurement list requires
1167 * the file hash calculated without the appended signature (i.e., the 'd-modsig'
1168 * field). Therefore, notify the user if they have the 'modsig' field but not
1169 * the 'd-modsig' field in the template.
1170 */
check_template_modsig(const struct ima_template_desc * template)1171 static void check_template_modsig(const struct ima_template_desc *template)
1172 {
1173 #define MSG "template with 'modsig' field also needs 'd-modsig' field\n"
1174 bool has_modsig, has_dmodsig;
1175 static bool checked;
1176 int i;
1177
1178 /* We only need to notify the user once. */
1179 if (checked)
1180 return;
1181
1182 has_modsig = has_dmodsig = false;
1183 for (i = 0; i < template->num_fields; i++) {
1184 if (!strcmp(template->fields[i]->field_id, "modsig"))
1185 has_modsig = true;
1186 else if (!strcmp(template->fields[i]->field_id, "d-modsig"))
1187 has_dmodsig = true;
1188 }
1189
1190 if (has_modsig && !has_dmodsig)
1191 pr_notice(MSG);
1192
1193 checked = true;
1194 #undef MSG
1195 }
1196
1197 /*
1198 * Warn if the template does not contain the given field.
1199 */
check_template_field(const struct ima_template_desc * template,const char * field,const char * msg)1200 static void check_template_field(const struct ima_template_desc *template,
1201 const char *field, const char *msg)
1202 {
1203 int i;
1204
1205 for (i = 0; i < template->num_fields; i++)
1206 if (!strcmp(template->fields[i]->field_id, field))
1207 return;
1208
1209 pr_notice_once("%s", msg);
1210 }
1211
ima_validate_rule(struct ima_rule_entry * entry)1212 static bool ima_validate_rule(struct ima_rule_entry *entry)
1213 {
1214 /* Ensure that the action is set and is compatible with the flags */
1215 if (entry->action == UNKNOWN)
1216 return false;
1217
1218 if (entry->action != MEASURE && entry->flags & IMA_PCR)
1219 return false;
1220
1221 if (entry->action != APPRAISE &&
1222 entry->flags & (IMA_DIGSIG_REQUIRED | IMA_MODSIG_ALLOWED |
1223 IMA_CHECK_BLACKLIST | IMA_VALIDATE_ALGOS))
1224 return false;
1225
1226 /*
1227 * The IMA_FUNC bit must be set if and only if there's a valid hook
1228 * function specified, and vice versa. Enforcing this property allows
1229 * for the NONE case below to validate a rule without an explicit hook
1230 * function.
1231 */
1232 if (((entry->flags & IMA_FUNC) && entry->func == NONE) ||
1233 (!(entry->flags & IMA_FUNC) && entry->func != NONE))
1234 return false;
1235
1236 /*
1237 * Ensure that the hook function is compatible with the other
1238 * components of the rule
1239 */
1240 switch (entry->func) {
1241 case NONE:
1242 case FILE_CHECK:
1243 case MMAP_CHECK:
1244 case BPRM_CHECK:
1245 case CREDS_CHECK:
1246 case POST_SETATTR:
1247 case FIRMWARE_CHECK:
1248 case POLICY_CHECK:
1249 if (entry->flags & ~(IMA_FUNC | IMA_MASK | IMA_FSMAGIC |
1250 IMA_UID | IMA_FOWNER | IMA_FSUUID |
1251 IMA_INMASK | IMA_EUID | IMA_PCR |
1252 IMA_FSNAME | IMA_GID | IMA_EGID |
1253 IMA_FGROUP | IMA_DIGSIG_REQUIRED |
1254 IMA_PERMIT_DIRECTIO | IMA_VALIDATE_ALGOS |
1255 IMA_VERITY_REQUIRED))
1256 return false;
1257
1258 break;
1259 case MODULE_CHECK:
1260 case KEXEC_KERNEL_CHECK:
1261 case KEXEC_INITRAMFS_CHECK:
1262 if (entry->flags & ~(IMA_FUNC | IMA_MASK | IMA_FSMAGIC |
1263 IMA_UID | IMA_FOWNER | IMA_FSUUID |
1264 IMA_INMASK | IMA_EUID | IMA_PCR |
1265 IMA_FSNAME | IMA_GID | IMA_EGID |
1266 IMA_FGROUP | IMA_DIGSIG_REQUIRED |
1267 IMA_PERMIT_DIRECTIO | IMA_MODSIG_ALLOWED |
1268 IMA_CHECK_BLACKLIST | IMA_VALIDATE_ALGOS))
1269 return false;
1270
1271 break;
1272 case KEXEC_CMDLINE:
1273 if (entry->action & ~(MEASURE | DONT_MEASURE))
1274 return false;
1275
1276 if (entry->flags & ~(IMA_FUNC | IMA_FSMAGIC | IMA_UID |
1277 IMA_FOWNER | IMA_FSUUID | IMA_EUID |
1278 IMA_PCR | IMA_FSNAME | IMA_GID | IMA_EGID |
1279 IMA_FGROUP))
1280 return false;
1281
1282 break;
1283 case KEY_CHECK:
1284 if (entry->action & ~(MEASURE | DONT_MEASURE))
1285 return false;
1286
1287 if (entry->flags & ~(IMA_FUNC | IMA_UID | IMA_GID | IMA_PCR |
1288 IMA_KEYRINGS))
1289 return false;
1290
1291 if (ima_rule_contains_lsm_cond(entry))
1292 return false;
1293
1294 break;
1295 case CRITICAL_DATA:
1296 if (entry->action & ~(MEASURE | DONT_MEASURE))
1297 return false;
1298
1299 if (entry->flags & ~(IMA_FUNC | IMA_UID | IMA_GID | IMA_PCR |
1300 IMA_LABEL))
1301 return false;
1302
1303 if (ima_rule_contains_lsm_cond(entry))
1304 return false;
1305
1306 break;
1307 case SETXATTR_CHECK:
1308 /* any action other than APPRAISE is unsupported */
1309 if (entry->action != APPRAISE)
1310 return false;
1311
1312 /* SETXATTR_CHECK requires an appraise_algos parameter */
1313 if (!(entry->flags & IMA_VALIDATE_ALGOS))
1314 return false;
1315
1316 /*
1317 * full policies are not supported, they would have too
1318 * much of a performance impact
1319 */
1320 if (entry->flags & ~(IMA_FUNC | IMA_VALIDATE_ALGOS))
1321 return false;
1322
1323 break;
1324 default:
1325 return false;
1326 }
1327
1328 /* Ensure that combinations of flags are compatible with each other */
1329 if (entry->flags & IMA_CHECK_BLACKLIST &&
1330 !(entry->flags & IMA_MODSIG_ALLOWED))
1331 return false;
1332
1333 /*
1334 * Unlike for regular IMA 'appraise' policy rules where security.ima
1335 * xattr may contain either a file hash or signature, the security.ima
1336 * xattr for fsverity must contain a file signature (sigv3). Ensure
1337 * that 'appraise' rules for fsverity require file signatures by
1338 * checking the IMA_DIGSIG_REQUIRED flag is set.
1339 */
1340 if (entry->action == APPRAISE &&
1341 (entry->flags & IMA_VERITY_REQUIRED) &&
1342 !(entry->flags & IMA_DIGSIG_REQUIRED))
1343 return false;
1344
1345 return true;
1346 }
1347
ima_parse_appraise_algos(char * arg)1348 static unsigned int ima_parse_appraise_algos(char *arg)
1349 {
1350 unsigned int res = 0;
1351 int idx;
1352 char *token;
1353
1354 while ((token = strsep(&arg, ",")) != NULL) {
1355 idx = match_string(hash_algo_name, HASH_ALGO__LAST, token);
1356
1357 if (idx < 0) {
1358 pr_err("unknown hash algorithm \"%s\"",
1359 token);
1360 return 0;
1361 }
1362
1363 if (!crypto_has_alg(hash_algo_name[idx], 0, 0)) {
1364 pr_err("unavailable hash algorithm \"%s\", check your kernel configuration",
1365 token);
1366 return 0;
1367 }
1368
1369 /* Add the hash algorithm to the 'allowed' bitfield */
1370 res |= (1U << idx);
1371 }
1372
1373 return res;
1374 }
1375
ima_parse_rule(char * rule,struct ima_rule_entry * entry)1376 static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
1377 {
1378 struct audit_buffer *ab;
1379 char *from;
1380 char *p;
1381 bool eid_token; /* either euid or egid */
1382 struct ima_template_desc *template_desc;
1383 int result = 0;
1384
1385 ab = integrity_audit_log_start(audit_context(), GFP_KERNEL,
1386 AUDIT_INTEGRITY_POLICY_RULE);
1387
1388 entry->uid = INVALID_UID;
1389 entry->gid = INVALID_GID;
1390 entry->fowner = INVALID_UID;
1391 entry->fgroup = INVALID_GID;
1392 entry->uid_op = &uid_eq;
1393 entry->gid_op = &gid_eq;
1394 entry->fowner_op = &uid_eq;
1395 entry->fgroup_op = &gid_eq;
1396 entry->action = UNKNOWN;
1397 while ((p = strsep(&rule, " \t")) != NULL) {
1398 substring_t args[MAX_OPT_ARGS];
1399 int token;
1400 unsigned long lnum;
1401
1402 if (result < 0)
1403 break;
1404 if ((*p == '\0') || (*p == ' ') || (*p == '\t'))
1405 continue;
1406 token = match_token(p, policy_tokens, args);
1407 switch (token) {
1408 case Opt_measure:
1409 ima_log_string(ab, "action", "measure");
1410
1411 if (entry->action != UNKNOWN)
1412 result = -EINVAL;
1413
1414 entry->action = MEASURE;
1415 break;
1416 case Opt_dont_measure:
1417 ima_log_string(ab, "action", "dont_measure");
1418
1419 if (entry->action != UNKNOWN)
1420 result = -EINVAL;
1421
1422 entry->action = DONT_MEASURE;
1423 break;
1424 case Opt_appraise:
1425 ima_log_string(ab, "action", "appraise");
1426
1427 if (entry->action != UNKNOWN)
1428 result = -EINVAL;
1429
1430 entry->action = APPRAISE;
1431 break;
1432 case Opt_dont_appraise:
1433 ima_log_string(ab, "action", "dont_appraise");
1434
1435 if (entry->action != UNKNOWN)
1436 result = -EINVAL;
1437
1438 entry->action = DONT_APPRAISE;
1439 break;
1440 case Opt_audit:
1441 ima_log_string(ab, "action", "audit");
1442
1443 if (entry->action != UNKNOWN)
1444 result = -EINVAL;
1445
1446 entry->action = AUDIT;
1447 break;
1448 case Opt_hash:
1449 ima_log_string(ab, "action", "hash");
1450
1451 if (entry->action != UNKNOWN)
1452 result = -EINVAL;
1453
1454 entry->action = HASH;
1455 break;
1456 case Opt_dont_hash:
1457 ima_log_string(ab, "action", "dont_hash");
1458
1459 if (entry->action != UNKNOWN)
1460 result = -EINVAL;
1461
1462 entry->action = DONT_HASH;
1463 break;
1464 case Opt_func:
1465 ima_log_string(ab, "func", args[0].from);
1466
1467 if (entry->func)
1468 result = -EINVAL;
1469
1470 if (strcmp(args[0].from, "FILE_CHECK") == 0)
1471 entry->func = FILE_CHECK;
1472 /* PATH_CHECK is for backwards compat */
1473 else if (strcmp(args[0].from, "PATH_CHECK") == 0)
1474 entry->func = FILE_CHECK;
1475 else if (strcmp(args[0].from, "MODULE_CHECK") == 0)
1476 entry->func = MODULE_CHECK;
1477 else if (strcmp(args[0].from, "FIRMWARE_CHECK") == 0)
1478 entry->func = FIRMWARE_CHECK;
1479 else if ((strcmp(args[0].from, "FILE_MMAP") == 0)
1480 || (strcmp(args[0].from, "MMAP_CHECK") == 0))
1481 entry->func = MMAP_CHECK;
1482 else if (strcmp(args[0].from, "BPRM_CHECK") == 0)
1483 entry->func = BPRM_CHECK;
1484 else if (strcmp(args[0].from, "CREDS_CHECK") == 0)
1485 entry->func = CREDS_CHECK;
1486 else if (strcmp(args[0].from, "KEXEC_KERNEL_CHECK") ==
1487 0)
1488 entry->func = KEXEC_KERNEL_CHECK;
1489 else if (strcmp(args[0].from, "KEXEC_INITRAMFS_CHECK")
1490 == 0)
1491 entry->func = KEXEC_INITRAMFS_CHECK;
1492 else if (strcmp(args[0].from, "POLICY_CHECK") == 0)
1493 entry->func = POLICY_CHECK;
1494 else if (strcmp(args[0].from, "KEXEC_CMDLINE") == 0)
1495 entry->func = KEXEC_CMDLINE;
1496 else if (IS_ENABLED(CONFIG_IMA_MEASURE_ASYMMETRIC_KEYS) &&
1497 strcmp(args[0].from, "KEY_CHECK") == 0)
1498 entry->func = KEY_CHECK;
1499 else if (strcmp(args[0].from, "CRITICAL_DATA") == 0)
1500 entry->func = CRITICAL_DATA;
1501 else if (strcmp(args[0].from, "SETXATTR_CHECK") == 0)
1502 entry->func = SETXATTR_CHECK;
1503 else
1504 result = -EINVAL;
1505 if (!result)
1506 entry->flags |= IMA_FUNC;
1507 break;
1508 case Opt_mask:
1509 ima_log_string(ab, "mask", args[0].from);
1510
1511 if (entry->mask)
1512 result = -EINVAL;
1513
1514 from = args[0].from;
1515 if (*from == '^')
1516 from++;
1517
1518 if ((strcmp(from, "MAY_EXEC")) == 0)
1519 entry->mask = MAY_EXEC;
1520 else if (strcmp(from, "MAY_WRITE") == 0)
1521 entry->mask = MAY_WRITE;
1522 else if (strcmp(from, "MAY_READ") == 0)
1523 entry->mask = MAY_READ;
1524 else if (strcmp(from, "MAY_APPEND") == 0)
1525 entry->mask = MAY_APPEND;
1526 else
1527 result = -EINVAL;
1528 if (!result)
1529 entry->flags |= (*args[0].from == '^')
1530 ? IMA_INMASK : IMA_MASK;
1531 break;
1532 case Opt_fsmagic:
1533 ima_log_string(ab, "fsmagic", args[0].from);
1534
1535 if (entry->fsmagic) {
1536 result = -EINVAL;
1537 break;
1538 }
1539
1540 result = kstrtoul(args[0].from, 16, &entry->fsmagic);
1541 if (!result)
1542 entry->flags |= IMA_FSMAGIC;
1543 break;
1544 case Opt_fsname:
1545 ima_log_string(ab, "fsname", args[0].from);
1546
1547 entry->fsname = kstrdup(args[0].from, GFP_KERNEL);
1548 if (!entry->fsname) {
1549 result = -ENOMEM;
1550 break;
1551 }
1552 result = 0;
1553 entry->flags |= IMA_FSNAME;
1554 break;
1555 case Opt_keyrings:
1556 ima_log_string(ab, "keyrings", args[0].from);
1557
1558 if (!IS_ENABLED(CONFIG_IMA_MEASURE_ASYMMETRIC_KEYS) ||
1559 entry->keyrings) {
1560 result = -EINVAL;
1561 break;
1562 }
1563
1564 entry->keyrings = ima_alloc_rule_opt_list(args);
1565 if (IS_ERR(entry->keyrings)) {
1566 result = PTR_ERR(entry->keyrings);
1567 entry->keyrings = NULL;
1568 break;
1569 }
1570
1571 entry->flags |= IMA_KEYRINGS;
1572 break;
1573 case Opt_label:
1574 ima_log_string(ab, "label", args[0].from);
1575
1576 if (entry->label) {
1577 result = -EINVAL;
1578 break;
1579 }
1580
1581 entry->label = ima_alloc_rule_opt_list(args);
1582 if (IS_ERR(entry->label)) {
1583 result = PTR_ERR(entry->label);
1584 entry->label = NULL;
1585 break;
1586 }
1587
1588 entry->flags |= IMA_LABEL;
1589 break;
1590 case Opt_fsuuid:
1591 ima_log_string(ab, "fsuuid", args[0].from);
1592
1593 if (!uuid_is_null(&entry->fsuuid)) {
1594 result = -EINVAL;
1595 break;
1596 }
1597
1598 result = uuid_parse(args[0].from, &entry->fsuuid);
1599 if (!result)
1600 entry->flags |= IMA_FSUUID;
1601 break;
1602 case Opt_uid_gt:
1603 case Opt_euid_gt:
1604 entry->uid_op = &uid_gt;
1605 fallthrough;
1606 case Opt_uid_lt:
1607 case Opt_euid_lt:
1608 if ((token == Opt_uid_lt) || (token == Opt_euid_lt))
1609 entry->uid_op = &uid_lt;
1610 fallthrough;
1611 case Opt_uid_eq:
1612 case Opt_euid_eq:
1613 eid_token = (token == Opt_euid_eq) ||
1614 (token == Opt_euid_gt) ||
1615 (token == Opt_euid_lt);
1616
1617 ima_log_string_op(ab, eid_token ? "euid" : "uid",
1618 args[0].from, token);
1619
1620 if (uid_valid(entry->uid)) {
1621 result = -EINVAL;
1622 break;
1623 }
1624
1625 result = kstrtoul(args[0].from, 10, &lnum);
1626 if (!result) {
1627 entry->uid = make_kuid(current_user_ns(),
1628 (uid_t) lnum);
1629 if (!uid_valid(entry->uid) ||
1630 (uid_t)lnum != lnum)
1631 result = -EINVAL;
1632 else
1633 entry->flags |= eid_token
1634 ? IMA_EUID : IMA_UID;
1635 }
1636 break;
1637 case Opt_gid_gt:
1638 case Opt_egid_gt:
1639 entry->gid_op = &gid_gt;
1640 fallthrough;
1641 case Opt_gid_lt:
1642 case Opt_egid_lt:
1643 if ((token == Opt_gid_lt) || (token == Opt_egid_lt))
1644 entry->gid_op = &gid_lt;
1645 fallthrough;
1646 case Opt_gid_eq:
1647 case Opt_egid_eq:
1648 eid_token = (token == Opt_egid_eq) ||
1649 (token == Opt_egid_gt) ||
1650 (token == Opt_egid_lt);
1651
1652 ima_log_string_op(ab, eid_token ? "egid" : "gid",
1653 args[0].from, token);
1654
1655 if (gid_valid(entry->gid)) {
1656 result = -EINVAL;
1657 break;
1658 }
1659
1660 result = kstrtoul(args[0].from, 10, &lnum);
1661 if (!result) {
1662 entry->gid = make_kgid(current_user_ns(),
1663 (gid_t)lnum);
1664 if (!gid_valid(entry->gid) ||
1665 (((gid_t)lnum) != lnum))
1666 result = -EINVAL;
1667 else
1668 entry->flags |= eid_token
1669 ? IMA_EGID : IMA_GID;
1670 }
1671 break;
1672 case Opt_fowner_gt:
1673 entry->fowner_op = &uid_gt;
1674 fallthrough;
1675 case Opt_fowner_lt:
1676 if (token == Opt_fowner_lt)
1677 entry->fowner_op = &uid_lt;
1678 fallthrough;
1679 case Opt_fowner_eq:
1680 ima_log_string_op(ab, "fowner", args[0].from, token);
1681
1682 if (uid_valid(entry->fowner)) {
1683 result = -EINVAL;
1684 break;
1685 }
1686
1687 result = kstrtoul(args[0].from, 10, &lnum);
1688 if (!result) {
1689 entry->fowner = make_kuid(current_user_ns(),
1690 (uid_t)lnum);
1691 if (!uid_valid(entry->fowner) ||
1692 (((uid_t)lnum) != lnum))
1693 result = -EINVAL;
1694 else
1695 entry->flags |= IMA_FOWNER;
1696 }
1697 break;
1698 case Opt_fgroup_gt:
1699 entry->fgroup_op = &gid_gt;
1700 fallthrough;
1701 case Opt_fgroup_lt:
1702 if (token == Opt_fgroup_lt)
1703 entry->fgroup_op = &gid_lt;
1704 fallthrough;
1705 case Opt_fgroup_eq:
1706 ima_log_string_op(ab, "fgroup", args[0].from, token);
1707
1708 if (gid_valid(entry->fgroup)) {
1709 result = -EINVAL;
1710 break;
1711 }
1712
1713 result = kstrtoul(args[0].from, 10, &lnum);
1714 if (!result) {
1715 entry->fgroup = make_kgid(current_user_ns(),
1716 (gid_t)lnum);
1717 if (!gid_valid(entry->fgroup) ||
1718 (((gid_t)lnum) != lnum))
1719 result = -EINVAL;
1720 else
1721 entry->flags |= IMA_FGROUP;
1722 }
1723 break;
1724 case Opt_obj_user:
1725 ima_log_string(ab, "obj_user", args[0].from);
1726 result = ima_lsm_rule_init(entry, args,
1727 LSM_OBJ_USER,
1728 AUDIT_OBJ_USER);
1729 break;
1730 case Opt_obj_role:
1731 ima_log_string(ab, "obj_role", args[0].from);
1732 result = ima_lsm_rule_init(entry, args,
1733 LSM_OBJ_ROLE,
1734 AUDIT_OBJ_ROLE);
1735 break;
1736 case Opt_obj_type:
1737 ima_log_string(ab, "obj_type", args[0].from);
1738 result = ima_lsm_rule_init(entry, args,
1739 LSM_OBJ_TYPE,
1740 AUDIT_OBJ_TYPE);
1741 break;
1742 case Opt_subj_user:
1743 ima_log_string(ab, "subj_user", args[0].from);
1744 result = ima_lsm_rule_init(entry, args,
1745 LSM_SUBJ_USER,
1746 AUDIT_SUBJ_USER);
1747 break;
1748 case Opt_subj_role:
1749 ima_log_string(ab, "subj_role", args[0].from);
1750 result = ima_lsm_rule_init(entry, args,
1751 LSM_SUBJ_ROLE,
1752 AUDIT_SUBJ_ROLE);
1753 break;
1754 case Opt_subj_type:
1755 ima_log_string(ab, "subj_type", args[0].from);
1756 result = ima_lsm_rule_init(entry, args,
1757 LSM_SUBJ_TYPE,
1758 AUDIT_SUBJ_TYPE);
1759 break;
1760 case Opt_digest_type:
1761 ima_log_string(ab, "digest_type", args[0].from);
1762 if (entry->flags & IMA_DIGSIG_REQUIRED)
1763 result = -EINVAL;
1764 else if ((strcmp(args[0].from, "verity")) == 0)
1765 entry->flags |= IMA_VERITY_REQUIRED;
1766 else
1767 result = -EINVAL;
1768 break;
1769 case Opt_appraise_type:
1770 ima_log_string(ab, "appraise_type", args[0].from);
1771
1772 if ((strcmp(args[0].from, "imasig")) == 0) {
1773 if (entry->flags & IMA_VERITY_REQUIRED)
1774 result = -EINVAL;
1775 else
1776 entry->flags |= IMA_DIGSIG_REQUIRED;
1777 } else if (strcmp(args[0].from, "sigv3") == 0) {
1778 /* Only fsverity supports sigv3 for now */
1779 if (entry->flags & IMA_VERITY_REQUIRED)
1780 entry->flags |= IMA_DIGSIG_REQUIRED;
1781 else
1782 result = -EINVAL;
1783 } else if (IS_ENABLED(CONFIG_IMA_APPRAISE_MODSIG) &&
1784 strcmp(args[0].from, "imasig|modsig") == 0) {
1785 if (entry->flags & IMA_VERITY_REQUIRED)
1786 result = -EINVAL;
1787 else
1788 entry->flags |= IMA_DIGSIG_REQUIRED |
1789 IMA_MODSIG_ALLOWED;
1790 } else {
1791 result = -EINVAL;
1792 }
1793 break;
1794 case Opt_appraise_flag:
1795 ima_log_string(ab, "appraise_flag", args[0].from);
1796 if (IS_ENABLED(CONFIG_IMA_APPRAISE_MODSIG) &&
1797 strstr(args[0].from, "blacklist"))
1798 entry->flags |= IMA_CHECK_BLACKLIST;
1799 else
1800 result = -EINVAL;
1801 break;
1802 case Opt_appraise_algos:
1803 ima_log_string(ab, "appraise_algos", args[0].from);
1804
1805 if (entry->allowed_algos) {
1806 result = -EINVAL;
1807 break;
1808 }
1809
1810 entry->allowed_algos =
1811 ima_parse_appraise_algos(args[0].from);
1812 /* invalid or empty list of algorithms */
1813 if (!entry->allowed_algos) {
1814 result = -EINVAL;
1815 break;
1816 }
1817
1818 entry->flags |= IMA_VALIDATE_ALGOS;
1819
1820 break;
1821 case Opt_permit_directio:
1822 entry->flags |= IMA_PERMIT_DIRECTIO;
1823 break;
1824 case Opt_pcr:
1825 ima_log_string(ab, "pcr", args[0].from);
1826
1827 result = kstrtoint(args[0].from, 10, &entry->pcr);
1828 if (result || INVALID_PCR(entry->pcr))
1829 result = -EINVAL;
1830 else
1831 entry->flags |= IMA_PCR;
1832
1833 break;
1834 case Opt_template:
1835 ima_log_string(ab, "template", args[0].from);
1836 if (entry->action != MEASURE) {
1837 result = -EINVAL;
1838 break;
1839 }
1840 template_desc = lookup_template_desc(args[0].from);
1841 if (!template_desc || entry->template) {
1842 result = -EINVAL;
1843 break;
1844 }
1845
1846 /*
1847 * template_desc_init_fields() does nothing if
1848 * the template is already initialised, so
1849 * it's safe to do this unconditionally
1850 */
1851 template_desc_init_fields(template_desc->fmt,
1852 &(template_desc->fields),
1853 &(template_desc->num_fields));
1854 entry->template = template_desc;
1855 break;
1856 case Opt_err:
1857 ima_log_string(ab, "UNKNOWN", p);
1858 result = -EINVAL;
1859 break;
1860 }
1861 }
1862 if (!result && !ima_validate_rule(entry))
1863 result = -EINVAL;
1864 else if (entry->action == APPRAISE)
1865 temp_ima_appraise |= ima_appraise_flag(entry->func);
1866
1867 if (!result && entry->flags & IMA_MODSIG_ALLOWED) {
1868 template_desc = entry->template ? entry->template :
1869 ima_template_desc_current();
1870 check_template_modsig(template_desc);
1871 }
1872
1873 /* d-ngv2 template field recommended for unsigned fs-verity digests */
1874 if (!result && entry->action == MEASURE &&
1875 entry->flags & IMA_VERITY_REQUIRED) {
1876 template_desc = entry->template ? entry->template :
1877 ima_template_desc_current();
1878 check_template_field(template_desc, "d-ngv2",
1879 "verity rules should include d-ngv2");
1880 }
1881
1882 audit_log_format(ab, "res=%d", !result);
1883 audit_log_end(ab);
1884 return result;
1885 }
1886
1887 /**
1888 * ima_parse_add_rule - add a rule to ima_policy_rules
1889 * @rule: ima measurement policy rule
1890 *
1891 * Avoid locking by allowing just one writer at a time in ima_write_policy()
1892 * Returns the length of the rule parsed, an error code on failure
1893 */
ima_parse_add_rule(char * rule)1894 ssize_t ima_parse_add_rule(char *rule)
1895 {
1896 static const char op[] = "update_policy";
1897 char *p;
1898 struct ima_rule_entry *entry;
1899 ssize_t result, len;
1900 int audit_info = 0;
1901
1902 p = strsep(&rule, "\n");
1903 len = strlen(p) + 1;
1904 p += strspn(p, " \t");
1905
1906 if (*p == '#' || *p == '\0')
1907 return len;
1908
1909 entry = kzalloc(sizeof(*entry), GFP_KERNEL);
1910 if (!entry) {
1911 integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
1912 NULL, op, "-ENOMEM", -ENOMEM, audit_info);
1913 return -ENOMEM;
1914 }
1915
1916 INIT_LIST_HEAD(&entry->list);
1917
1918 result = ima_parse_rule(p, entry);
1919 if (result) {
1920 ima_free_rule(entry);
1921 integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
1922 NULL, op, "invalid-policy", result,
1923 audit_info);
1924 return result;
1925 }
1926
1927 list_add_tail(&entry->list, &ima_temp_rules);
1928
1929 return len;
1930 }
1931
1932 /**
1933 * ima_delete_rules() called to cleanup invalid in-flight policy.
1934 * We don't need locking as we operate on the temp list, which is
1935 * different from the active one. There is also only one user of
1936 * ima_delete_rules() at a time.
1937 */
ima_delete_rules(void)1938 void ima_delete_rules(void)
1939 {
1940 struct ima_rule_entry *entry, *tmp;
1941
1942 temp_ima_appraise = 0;
1943 list_for_each_entry_safe(entry, tmp, &ima_temp_rules, list) {
1944 list_del(&entry->list);
1945 ima_free_rule(entry);
1946 }
1947 }
1948
1949 #define __ima_hook_stringify(func, str) (#func),
1950
1951 const char *const func_tokens[] = {
1952 __ima_hooks(__ima_hook_stringify)
1953 };
1954
1955 #ifdef CONFIG_IMA_READ_POLICY
1956 enum {
1957 mask_exec = 0, mask_write, mask_read, mask_append
1958 };
1959
1960 static const char *const mask_tokens[] = {
1961 "^MAY_EXEC",
1962 "^MAY_WRITE",
1963 "^MAY_READ",
1964 "^MAY_APPEND"
1965 };
1966
ima_policy_start(struct seq_file * m,loff_t * pos)1967 void *ima_policy_start(struct seq_file *m, loff_t *pos)
1968 {
1969 loff_t l = *pos;
1970 struct ima_rule_entry *entry;
1971 struct list_head *ima_rules_tmp;
1972
1973 rcu_read_lock();
1974 ima_rules_tmp = rcu_dereference(ima_rules);
1975 list_for_each_entry_rcu(entry, ima_rules_tmp, list) {
1976 if (!l--) {
1977 rcu_read_unlock();
1978 return entry;
1979 }
1980 }
1981 rcu_read_unlock();
1982 return NULL;
1983 }
1984
ima_policy_next(struct seq_file * m,void * v,loff_t * pos)1985 void *ima_policy_next(struct seq_file *m, void *v, loff_t *pos)
1986 {
1987 struct ima_rule_entry *entry = v;
1988
1989 rcu_read_lock();
1990 entry = list_entry_rcu(entry->list.next, struct ima_rule_entry, list);
1991 rcu_read_unlock();
1992 (*pos)++;
1993
1994 return (&entry->list == &ima_default_rules ||
1995 &entry->list == &ima_policy_rules) ? NULL : entry;
1996 }
1997
ima_policy_stop(struct seq_file * m,void * v)1998 void ima_policy_stop(struct seq_file *m, void *v)
1999 {
2000 }
2001
2002 #define pt(token) policy_tokens[token].pattern
2003 #define mt(token) mask_tokens[token]
2004
2005 /*
2006 * policy_func_show - display the ima_hooks policy rule
2007 */
policy_func_show(struct seq_file * m,enum ima_hooks func)2008 static void policy_func_show(struct seq_file *m, enum ima_hooks func)
2009 {
2010 if (func > 0 && func < MAX_CHECK)
2011 seq_printf(m, "func=%s ", func_tokens[func]);
2012 else
2013 seq_printf(m, "func=%d ", func);
2014 }
2015
ima_show_rule_opt_list(struct seq_file * m,const struct ima_rule_opt_list * opt_list)2016 static void ima_show_rule_opt_list(struct seq_file *m,
2017 const struct ima_rule_opt_list *opt_list)
2018 {
2019 size_t i;
2020
2021 for (i = 0; i < opt_list->count; i++)
2022 seq_printf(m, "%s%s", i ? "|" : "", opt_list->items[i]);
2023 }
2024
ima_policy_show_appraise_algos(struct seq_file * m,unsigned int allowed_hashes)2025 static void ima_policy_show_appraise_algos(struct seq_file *m,
2026 unsigned int allowed_hashes)
2027 {
2028 int idx, list_size = 0;
2029
2030 for (idx = 0; idx < HASH_ALGO__LAST; idx++) {
2031 if (!(allowed_hashes & (1U << idx)))
2032 continue;
2033
2034 /* only add commas if the list contains multiple entries */
2035 if (list_size++)
2036 seq_puts(m, ",");
2037
2038 seq_puts(m, hash_algo_name[idx]);
2039 }
2040 }
2041
ima_policy_show(struct seq_file * m,void * v)2042 int ima_policy_show(struct seq_file *m, void *v)
2043 {
2044 struct ima_rule_entry *entry = v;
2045 int i;
2046 char tbuf[64] = {0,};
2047 int offset = 0;
2048
2049 rcu_read_lock();
2050
2051 /* Do not print rules with inactive LSM labels */
2052 for (i = 0; i < MAX_LSM_RULES; i++) {
2053 if (entry->lsm[i].args_p && !entry->lsm[i].rule) {
2054 rcu_read_unlock();
2055 return 0;
2056 }
2057 }
2058
2059 if (entry->action & MEASURE)
2060 seq_puts(m, pt(Opt_measure));
2061 if (entry->action & DONT_MEASURE)
2062 seq_puts(m, pt(Opt_dont_measure));
2063 if (entry->action & APPRAISE)
2064 seq_puts(m, pt(Opt_appraise));
2065 if (entry->action & DONT_APPRAISE)
2066 seq_puts(m, pt(Opt_dont_appraise));
2067 if (entry->action & AUDIT)
2068 seq_puts(m, pt(Opt_audit));
2069 if (entry->action & HASH)
2070 seq_puts(m, pt(Opt_hash));
2071 if (entry->action & DONT_HASH)
2072 seq_puts(m, pt(Opt_dont_hash));
2073
2074 seq_puts(m, " ");
2075
2076 if (entry->flags & IMA_FUNC)
2077 policy_func_show(m, entry->func);
2078
2079 if ((entry->flags & IMA_MASK) || (entry->flags & IMA_INMASK)) {
2080 if (entry->flags & IMA_MASK)
2081 offset = 1;
2082 if (entry->mask & MAY_EXEC)
2083 seq_printf(m, pt(Opt_mask), mt(mask_exec) + offset);
2084 if (entry->mask & MAY_WRITE)
2085 seq_printf(m, pt(Opt_mask), mt(mask_write) + offset);
2086 if (entry->mask & MAY_READ)
2087 seq_printf(m, pt(Opt_mask), mt(mask_read) + offset);
2088 if (entry->mask & MAY_APPEND)
2089 seq_printf(m, pt(Opt_mask), mt(mask_append) + offset);
2090 seq_puts(m, " ");
2091 }
2092
2093 if (entry->flags & IMA_FSMAGIC) {
2094 snprintf(tbuf, sizeof(tbuf), "0x%lx", entry->fsmagic);
2095 seq_printf(m, pt(Opt_fsmagic), tbuf);
2096 seq_puts(m, " ");
2097 }
2098
2099 if (entry->flags & IMA_FSNAME) {
2100 snprintf(tbuf, sizeof(tbuf), "%s", entry->fsname);
2101 seq_printf(m, pt(Opt_fsname), tbuf);
2102 seq_puts(m, " ");
2103 }
2104
2105 if (entry->flags & IMA_KEYRINGS) {
2106 seq_puts(m, "keyrings=");
2107 ima_show_rule_opt_list(m, entry->keyrings);
2108 seq_puts(m, " ");
2109 }
2110
2111 if (entry->flags & IMA_LABEL) {
2112 seq_puts(m, "label=");
2113 ima_show_rule_opt_list(m, entry->label);
2114 seq_puts(m, " ");
2115 }
2116
2117 if (entry->flags & IMA_PCR) {
2118 snprintf(tbuf, sizeof(tbuf), "%d", entry->pcr);
2119 seq_printf(m, pt(Opt_pcr), tbuf);
2120 seq_puts(m, " ");
2121 }
2122
2123 if (entry->flags & IMA_FSUUID) {
2124 seq_printf(m, "fsuuid=%pU", &entry->fsuuid);
2125 seq_puts(m, " ");
2126 }
2127
2128 if (entry->flags & IMA_UID) {
2129 snprintf(tbuf, sizeof(tbuf), "%d", __kuid_val(entry->uid));
2130 if (entry->uid_op == &uid_gt)
2131 seq_printf(m, pt(Opt_uid_gt), tbuf);
2132 else if (entry->uid_op == &uid_lt)
2133 seq_printf(m, pt(Opt_uid_lt), tbuf);
2134 else
2135 seq_printf(m, pt(Opt_uid_eq), tbuf);
2136 seq_puts(m, " ");
2137 }
2138
2139 if (entry->flags & IMA_EUID) {
2140 snprintf(tbuf, sizeof(tbuf), "%d", __kuid_val(entry->uid));
2141 if (entry->uid_op == &uid_gt)
2142 seq_printf(m, pt(Opt_euid_gt), tbuf);
2143 else if (entry->uid_op == &uid_lt)
2144 seq_printf(m, pt(Opt_euid_lt), tbuf);
2145 else
2146 seq_printf(m, pt(Opt_euid_eq), tbuf);
2147 seq_puts(m, " ");
2148 }
2149
2150 if (entry->flags & IMA_GID) {
2151 snprintf(tbuf, sizeof(tbuf), "%d", __kgid_val(entry->gid));
2152 if (entry->gid_op == &gid_gt)
2153 seq_printf(m, pt(Opt_gid_gt), tbuf);
2154 else if (entry->gid_op == &gid_lt)
2155 seq_printf(m, pt(Opt_gid_lt), tbuf);
2156 else
2157 seq_printf(m, pt(Opt_gid_eq), tbuf);
2158 seq_puts(m, " ");
2159 }
2160
2161 if (entry->flags & IMA_EGID) {
2162 snprintf(tbuf, sizeof(tbuf), "%d", __kgid_val(entry->gid));
2163 if (entry->gid_op == &gid_gt)
2164 seq_printf(m, pt(Opt_egid_gt), tbuf);
2165 else if (entry->gid_op == &gid_lt)
2166 seq_printf(m, pt(Opt_egid_lt), tbuf);
2167 else
2168 seq_printf(m, pt(Opt_egid_eq), tbuf);
2169 seq_puts(m, " ");
2170 }
2171
2172 if (entry->flags & IMA_FOWNER) {
2173 snprintf(tbuf, sizeof(tbuf), "%d", __kuid_val(entry->fowner));
2174 if (entry->fowner_op == &uid_gt)
2175 seq_printf(m, pt(Opt_fowner_gt), tbuf);
2176 else if (entry->fowner_op == &uid_lt)
2177 seq_printf(m, pt(Opt_fowner_lt), tbuf);
2178 else
2179 seq_printf(m, pt(Opt_fowner_eq), tbuf);
2180 seq_puts(m, " ");
2181 }
2182
2183 if (entry->flags & IMA_FGROUP) {
2184 snprintf(tbuf, sizeof(tbuf), "%d", __kgid_val(entry->fgroup));
2185 if (entry->fgroup_op == &gid_gt)
2186 seq_printf(m, pt(Opt_fgroup_gt), tbuf);
2187 else if (entry->fgroup_op == &gid_lt)
2188 seq_printf(m, pt(Opt_fgroup_lt), tbuf);
2189 else
2190 seq_printf(m, pt(Opt_fgroup_eq), tbuf);
2191 seq_puts(m, " ");
2192 }
2193
2194 if (entry->flags & IMA_VALIDATE_ALGOS) {
2195 seq_puts(m, "appraise_algos=");
2196 ima_policy_show_appraise_algos(m, entry->allowed_algos);
2197 seq_puts(m, " ");
2198 }
2199
2200 for (i = 0; i < MAX_LSM_RULES; i++) {
2201 if (entry->lsm[i].rule) {
2202 switch (i) {
2203 case LSM_OBJ_USER:
2204 seq_printf(m, pt(Opt_obj_user),
2205 entry->lsm[i].args_p);
2206 break;
2207 case LSM_OBJ_ROLE:
2208 seq_printf(m, pt(Opt_obj_role),
2209 entry->lsm[i].args_p);
2210 break;
2211 case LSM_OBJ_TYPE:
2212 seq_printf(m, pt(Opt_obj_type),
2213 entry->lsm[i].args_p);
2214 break;
2215 case LSM_SUBJ_USER:
2216 seq_printf(m, pt(Opt_subj_user),
2217 entry->lsm[i].args_p);
2218 break;
2219 case LSM_SUBJ_ROLE:
2220 seq_printf(m, pt(Opt_subj_role),
2221 entry->lsm[i].args_p);
2222 break;
2223 case LSM_SUBJ_TYPE:
2224 seq_printf(m, pt(Opt_subj_type),
2225 entry->lsm[i].args_p);
2226 break;
2227 }
2228 seq_puts(m, " ");
2229 }
2230 }
2231 if (entry->template)
2232 seq_printf(m, "template=%s ", entry->template->name);
2233 if (entry->flags & IMA_DIGSIG_REQUIRED) {
2234 if (entry->flags & IMA_VERITY_REQUIRED)
2235 seq_puts(m, "appraise_type=sigv3 ");
2236 else if (entry->flags & IMA_MODSIG_ALLOWED)
2237 seq_puts(m, "appraise_type=imasig|modsig ");
2238 else
2239 seq_puts(m, "appraise_type=imasig ");
2240 }
2241 if (entry->flags & IMA_VERITY_REQUIRED)
2242 seq_puts(m, "digest_type=verity ");
2243 if (entry->flags & IMA_CHECK_BLACKLIST)
2244 seq_puts(m, "appraise_flag=check_blacklist ");
2245 if (entry->flags & IMA_PERMIT_DIRECTIO)
2246 seq_puts(m, "permit_directio ");
2247 rcu_read_unlock();
2248 seq_puts(m, "\n");
2249 return 0;
2250 }
2251 #endif /* CONFIG_IMA_READ_POLICY */
2252
2253 #if defined(CONFIG_IMA_APPRAISE) && defined(CONFIG_INTEGRITY_TRUSTED_KEYRING)
2254 /*
2255 * ima_appraise_signature: whether IMA will appraise a given function using
2256 * an IMA digital signature. This is restricted to cases where the kernel
2257 * has a set of built-in trusted keys in order to avoid an attacker simply
2258 * loading additional keys.
2259 */
ima_appraise_signature(enum kernel_read_file_id id)2260 bool ima_appraise_signature(enum kernel_read_file_id id)
2261 {
2262 struct ima_rule_entry *entry;
2263 bool found = false;
2264 enum ima_hooks func;
2265 struct list_head *ima_rules_tmp;
2266
2267 if (id >= READING_MAX_ID)
2268 return false;
2269
2270 if (id == READING_KEXEC_IMAGE && !(ima_appraise & IMA_APPRAISE_ENFORCE)
2271 && security_locked_down(LOCKDOWN_KEXEC))
2272 return false;
2273
2274 func = read_idmap[id] ?: FILE_CHECK;
2275
2276 rcu_read_lock();
2277 ima_rules_tmp = rcu_dereference(ima_rules);
2278 list_for_each_entry_rcu(entry, ima_rules_tmp, list) {
2279 if (entry->action != APPRAISE)
2280 continue;
2281
2282 /*
2283 * A generic entry will match, but otherwise require that it
2284 * match the func we're looking for
2285 */
2286 if (entry->func && entry->func != func)
2287 continue;
2288
2289 /*
2290 * We require this to be a digital signature, not a raw IMA
2291 * hash.
2292 */
2293 if (entry->flags & IMA_DIGSIG_REQUIRED)
2294 found = true;
2295
2296 /*
2297 * We've found a rule that matches, so break now even if it
2298 * didn't require a digital signature - a later rule that does
2299 * won't override it, so would be a false positive.
2300 */
2301 break;
2302 }
2303
2304 rcu_read_unlock();
2305 return found;
2306 }
2307 #endif /* CONFIG_IMA_APPRAISE && CONFIG_INTEGRITY_TRUSTED_KEYRING */
2308