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 ima_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[] __counted_by(count);
72 };
73
74 /*
75 * These comparators are needed nowhere outside of ima so just define them here.
76 * This pattern should hopefully never be needed outside of ima.
77 */
78 static inline bool vfsuid_gt_kuid(vfsuid_t vfsuid, kuid_t kuid)
79 {
80 return __vfsuid_val(vfsuid) > __kuid_val(kuid);
81 }
82
83 static inline bool vfsgid_gt_kgid(vfsgid_t vfsgid, kgid_t kgid)
84 {
85 return __vfsgid_val(vfsgid) > __kgid_val(kgid);
86 }
87
88 static inline bool vfsuid_lt_kuid(vfsuid_t vfsuid, kuid_t kuid)
89 {
90 return __vfsuid_val(vfsuid) < __kuid_val(kuid);
91 }
92
93 static inline bool vfsgid_lt_kgid(vfsgid_t vfsgid, kgid_t kgid)
94 {
95 return __vfsgid_val(vfsgid) < __kgid_val(kgid);
96 }
97
98 struct ima_rule_entry {
99 struct list_head list;
100 int action;
101 unsigned int flags;
102 enum ima_hooks func;
103 int mask;
104 unsigned long fsmagic;
105 uuid_t fsuuid;
106 kuid_t uid;
107 kgid_t gid;
108 kuid_t fowner;
109 kgid_t fgroup;
110 bool (*uid_op)(kuid_t cred_uid, kuid_t rule_uid); /* Handlers for operators */
111 bool (*gid_op)(kgid_t cred_gid, kgid_t rule_gid);
112 bool (*fowner_op)(vfsuid_t vfsuid, kuid_t rule_uid); /* vfsuid_eq_kuid(), vfsuid_gt_kuid(), vfsuid_lt_kuid() */
113 bool (*fgroup_op)(vfsgid_t vfsgid, kgid_t rule_gid); /* vfsgid_eq_kgid(), vfsgid_gt_kgid(), vfsgid_lt_kgid() */
114 int pcr;
115 unsigned int allowed_algos; /* bitfield of allowed hash algorithms */
116 struct {
117 void *rule; /* LSM file metadata specific */
118 char *args_p; /* audit value */
119 int type; /* audit type */
120 } lsm[MAX_LSM_RULES];
121 char *fsname;
122 struct ima_rule_opt_list *keyrings; /* Measure keys added to these keyrings */
123 struct ima_rule_opt_list *label; /* Measure data grouped under this label */
124 struct ima_template_desc *template;
125 };
126
127 /*
128 * sanity check in case the kernels gains more hash algorithms that can
129 * fit in an unsigned int
130 */
131 static_assert(
132 8 * sizeof(unsigned int) >= HASH_ALGO__LAST,
133 "The bitfield allowed_algos in ima_rule_entry is too small to contain all the supported hash algorithms, consider using a bigger type");
134
135 /*
136 * Without LSM specific knowledge, the default policy can only be
137 * written in terms of .action, .func, .mask, .fsmagic, .uid, .gid,
138 * .fowner, and .fgroup
139 */
140
141 /*
142 * The minimum rule set to allow for full TCB coverage. Measures all files
143 * opened or mmap for exec and everything read by root. Dangerous because
144 * normal users can easily run the machine out of memory simply building
145 * and running executables.
146 */
147 static struct ima_rule_entry dont_measure_rules[] __ro_after_init = {
148 {.action = DONT_MEASURE, .fsmagic = PROC_SUPER_MAGIC, .flags = IMA_FSMAGIC},
149 {.action = DONT_MEASURE, .fsmagic = SYSFS_MAGIC, .flags = IMA_FSMAGIC},
150 {.action = DONT_MEASURE, .fsmagic = DEBUGFS_MAGIC, .flags = IMA_FSMAGIC},
151 {.action = DONT_MEASURE, .fsmagic = TMPFS_MAGIC, .flags = IMA_FSMAGIC},
152 {.action = DONT_MEASURE, .fsmagic = DEVPTS_SUPER_MAGIC, .flags = IMA_FSMAGIC},
153 {.action = DONT_MEASURE, .fsmagic = BINFMTFS_MAGIC, .flags = IMA_FSMAGIC},
154 {.action = DONT_MEASURE, .fsmagic = SECURITYFS_MAGIC, .flags = IMA_FSMAGIC},
155 {.action = DONT_MEASURE, .fsmagic = SELINUX_MAGIC, .flags = IMA_FSMAGIC},
156 {.action = DONT_MEASURE, .fsmagic = SMACK_MAGIC, .flags = IMA_FSMAGIC},
157 {.action = DONT_MEASURE, .fsmagic = CGROUP_SUPER_MAGIC,
158 .flags = IMA_FSMAGIC},
159 {.action = DONT_MEASURE, .fsmagic = CGROUP2_SUPER_MAGIC,
160 .flags = IMA_FSMAGIC},
161 {.action = DONT_MEASURE, .fsmagic = NSFS_MAGIC, .flags = IMA_FSMAGIC},
162 {.action = DONT_MEASURE, .fsmagic = EFIVARFS_MAGIC, .flags = IMA_FSMAGIC}
163 };
164
165 static struct ima_rule_entry original_measurement_rules[] __ro_after_init = {
166 {.action = MEASURE, .func = MMAP_CHECK, .mask = MAY_EXEC,
167 .flags = IMA_FUNC | IMA_MASK},
168 {.action = MEASURE, .func = BPRM_CHECK, .mask = MAY_EXEC,
169 .flags = IMA_FUNC | IMA_MASK},
170 {.action = MEASURE, .func = FILE_CHECK, .mask = MAY_READ,
171 .uid = GLOBAL_ROOT_UID, .uid_op = &uid_eq,
172 .flags = IMA_FUNC | IMA_MASK | IMA_UID},
173 {.action = MEASURE, .func = MODULE_CHECK, .flags = IMA_FUNC},
174 {.action = MEASURE, .func = FIRMWARE_CHECK, .flags = IMA_FUNC},
175 };
176
177 static struct ima_rule_entry default_measurement_rules[] __ro_after_init = {
178 {.action = MEASURE, .func = MMAP_CHECK, .mask = MAY_EXEC,
179 .flags = IMA_FUNC | IMA_MASK},
180 {.action = MEASURE, .func = BPRM_CHECK, .mask = MAY_EXEC,
181 .flags = IMA_FUNC | IMA_MASK},
182 {.action = MEASURE, .func = FILE_CHECK, .mask = MAY_READ,
183 .uid = GLOBAL_ROOT_UID, .uid_op = &uid_eq,
184 .flags = IMA_FUNC | IMA_INMASK | IMA_EUID},
185 {.action = MEASURE, .func = FILE_CHECK, .mask = MAY_READ,
186 .uid = GLOBAL_ROOT_UID, .uid_op = &uid_eq,
187 .flags = IMA_FUNC | IMA_INMASK | IMA_UID},
188 {.action = MEASURE, .func = MODULE_CHECK, .flags = IMA_FUNC},
189 {.action = MEASURE, .func = FIRMWARE_CHECK, .flags = IMA_FUNC},
190 {.action = MEASURE, .func = POLICY_CHECK, .flags = IMA_FUNC},
191 };
192
193 static struct ima_rule_entry default_appraise_rules[] __ro_after_init = {
194 {.action = DONT_APPRAISE, .fsmagic = PROC_SUPER_MAGIC, .flags = IMA_FSMAGIC},
195 {.action = DONT_APPRAISE, .fsmagic = SYSFS_MAGIC, .flags = IMA_FSMAGIC},
196 {.action = DONT_APPRAISE, .fsmagic = DEBUGFS_MAGIC, .flags = IMA_FSMAGIC},
197 {.action = DONT_APPRAISE, .fsmagic = TMPFS_MAGIC, .flags = IMA_FSMAGIC},
198 {.action = DONT_APPRAISE, .fsmagic = RAMFS_MAGIC, .flags = IMA_FSMAGIC},
199 {.action = DONT_APPRAISE, .fsmagic = DEVPTS_SUPER_MAGIC, .flags = IMA_FSMAGIC},
200 {.action = DONT_APPRAISE, .fsmagic = BINFMTFS_MAGIC, .flags = IMA_FSMAGIC},
201 {.action = DONT_APPRAISE, .fsmagic = SECURITYFS_MAGIC, .flags = IMA_FSMAGIC},
202 {.action = DONT_APPRAISE, .fsmagic = SELINUX_MAGIC, .flags = IMA_FSMAGIC},
203 {.action = DONT_APPRAISE, .fsmagic = SMACK_MAGIC, .flags = IMA_FSMAGIC},
204 {.action = DONT_APPRAISE, .fsmagic = NSFS_MAGIC, .flags = IMA_FSMAGIC},
205 {.action = DONT_APPRAISE, .fsmagic = EFIVARFS_MAGIC, .flags = IMA_FSMAGIC},
206 {.action = DONT_APPRAISE, .fsmagic = CGROUP_SUPER_MAGIC, .flags = IMA_FSMAGIC},
207 {.action = DONT_APPRAISE, .fsmagic = CGROUP2_SUPER_MAGIC, .flags = IMA_FSMAGIC},
208 #ifdef CONFIG_IMA_WRITE_POLICY
209 {.action = APPRAISE, .func = POLICY_CHECK,
210 .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
211 #endif
212 #ifndef CONFIG_IMA_APPRAISE_SIGNED_INIT
213 {.action = APPRAISE, .fowner = GLOBAL_ROOT_UID, .fowner_op = &vfsuid_eq_kuid,
214 .flags = IMA_FOWNER},
215 #else
216 /* force signature */
217 {.action = APPRAISE, .fowner = GLOBAL_ROOT_UID, .fowner_op = &vfsuid_eq_kuid,
218 .flags = IMA_FOWNER | IMA_DIGSIG_REQUIRED},
219 #endif
220 };
221
222 static struct ima_rule_entry build_appraise_rules[] __ro_after_init = {
223 #ifdef CONFIG_IMA_APPRAISE_REQUIRE_MODULE_SIGS
224 {.action = APPRAISE, .func = MODULE_CHECK,
225 .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
226 #endif
227 #ifdef CONFIG_IMA_APPRAISE_REQUIRE_FIRMWARE_SIGS
228 {.action = APPRAISE, .func = FIRMWARE_CHECK,
229 .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
230 #endif
231 #ifdef CONFIG_IMA_APPRAISE_REQUIRE_KEXEC_SIGS
232 {.action = APPRAISE, .func = KEXEC_KERNEL_CHECK,
233 .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
234 #endif
235 #ifdef CONFIG_IMA_APPRAISE_REQUIRE_POLICY_SIGS
236 {.action = APPRAISE, .func = POLICY_CHECK,
237 .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
238 #endif
239 };
240
241 static struct ima_rule_entry secure_boot_rules[] __ro_after_init = {
242 {.action = APPRAISE, .func = MODULE_CHECK,
243 .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
244 {.action = APPRAISE, .func = FIRMWARE_CHECK,
245 .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
246 {.action = APPRAISE, .func = KEXEC_KERNEL_CHECK,
247 .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
248 {.action = APPRAISE, .func = POLICY_CHECK,
249 .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
250 };
251
252 static struct ima_rule_entry critical_data_rules[] __ro_after_init = {
253 {.action = MEASURE, .func = CRITICAL_DATA, .flags = IMA_FUNC},
254 };
255
256 /* An array of architecture specific rules */
257 static struct ima_rule_entry *arch_policy_entry __ro_after_init;
258
259 static LIST_HEAD(ima_default_rules);
260 static LIST_HEAD(ima_policy_rules);
261 static LIST_HEAD(ima_temp_rules);
262 static struct list_head __rcu *ima_rules = (struct list_head __rcu *)(&ima_default_rules);
263
264 static int ima_policy __initdata;
265
266 static int __init default_measure_policy_setup(char *str)
267 {
268 if (ima_policy)
269 return 1;
270
271 ima_policy = ORIGINAL_TCB;
272 return 1;
273 }
274 __setup("ima_tcb", default_measure_policy_setup);
275
276 static bool ima_use_appraise_tcb __initdata;
277 static bool ima_use_secure_boot __initdata;
278 static bool ima_use_critical_data __initdata;
279 static bool ima_fail_unverifiable_sigs __ro_after_init;
280 static int __init policy_setup(char *str)
281 {
282 char *p;
283
284 while ((p = strsep(&str, " |\n")) != NULL) {
285 if (*p == ' ')
286 continue;
287 if ((strcmp(p, "tcb") == 0) && !ima_policy)
288 ima_policy = DEFAULT_TCB;
289 else if (strcmp(p, "appraise_tcb") == 0)
290 ima_use_appraise_tcb = true;
291 else if (strcmp(p, "secure_boot") == 0)
292 ima_use_secure_boot = true;
293 else if (strcmp(p, "critical_data") == 0)
294 ima_use_critical_data = true;
295 else if (strcmp(p, "fail_securely") == 0)
296 ima_fail_unverifiable_sigs = true;
297 else
298 pr_err("policy \"%s\" not found", p);
299 }
300
301 return 1;
302 }
303 __setup("ima_policy=", policy_setup);
304
305 static int __init default_appraise_policy_setup(char *str)
306 {
307 ima_use_appraise_tcb = true;
308 return 1;
309 }
310 __setup("ima_appraise_tcb", default_appraise_policy_setup);
311
312 static struct ima_rule_opt_list *ima_alloc_rule_opt_list(const substring_t *src)
313 {
314 struct ima_rule_opt_list *opt_list;
315 size_t count = 0;
316 char *src_copy;
317 char *cur, *next;
318 size_t i;
319
320 src_copy = match_strdup(src);
321 if (!src_copy)
322 return ERR_PTR(-ENOMEM);
323
324 next = src_copy;
325 while ((cur = strsep(&next, "|"))) {
326 /* Don't accept an empty list item */
327 if (!(*cur)) {
328 kfree(src_copy);
329 return ERR_PTR(-EINVAL);
330 }
331 count++;
332 }
333
334 /* Don't accept an empty list */
335 if (!count) {
336 kfree(src_copy);
337 return ERR_PTR(-EINVAL);
338 }
339
340 opt_list = kzalloc(struct_size(opt_list, items, count), GFP_KERNEL);
341 if (!opt_list) {
342 kfree(src_copy);
343 return ERR_PTR(-ENOMEM);
344 }
345 opt_list->count = count;
346
347 /*
348 * strsep() has already replaced all instances of '|' with '\0',
349 * leaving a byte sequence of NUL-terminated strings. Reference each
350 * string with the array of items.
351 *
352 * IMPORTANT: Ownership of the allocated buffer is transferred from
353 * src_copy to the first element in the items array. To free the
354 * buffer, kfree() must only be called on the first element of the
355 * array.
356 */
357 for (i = 0, cur = src_copy; i < count; i++) {
358 opt_list->items[i] = cur;
359 cur = strchr(cur, '\0') + 1;
360 }
361
362 return opt_list;
363 }
364
365 static void ima_free_rule_opt_list(struct ima_rule_opt_list *opt_list)
366 {
367 if (!opt_list)
368 return;
369
370 if (opt_list->count) {
371 kfree(opt_list->items[0]);
372 opt_list->count = 0;
373 }
374
375 kfree(opt_list);
376 }
377
378 static void ima_lsm_free_rule(struct ima_rule_entry *entry)
379 {
380 int i;
381
382 for (i = 0; i < MAX_LSM_RULES; i++) {
383 ima_filter_rule_free(entry->lsm[i].rule);
384 kfree(entry->lsm[i].args_p);
385 }
386 }
387
388 static void ima_free_rule(struct ima_rule_entry *entry)
389 {
390 if (!entry)
391 return;
392
393 /*
394 * entry->template->fields may be allocated in ima_parse_rule() but that
395 * reference is owned by the corresponding ima_template_desc element in
396 * the defined_templates list and cannot be freed here
397 */
398 kfree(entry->fsname);
399 ima_free_rule_opt_list(entry->keyrings);
400 ima_lsm_free_rule(entry);
401 kfree(entry);
402 }
403
404 static struct ima_rule_entry *ima_lsm_copy_rule(struct ima_rule_entry *entry,
405 gfp_t gfp)
406 {
407 struct ima_rule_entry *nentry;
408 int i;
409
410 /*
411 * Immutable elements are copied over as pointers and data; only
412 * lsm rules can change
413 */
414 nentry = kmemdup(entry, sizeof(*nentry), gfp);
415 if (!nentry)
416 return NULL;
417
418 memset(nentry->lsm, 0, sizeof_field(struct ima_rule_entry, lsm));
419
420 for (i = 0; i < MAX_LSM_RULES; i++) {
421 if (!entry->lsm[i].args_p)
422 continue;
423
424 nentry->lsm[i].type = entry->lsm[i].type;
425 nentry->lsm[i].args_p = entry->lsm[i].args_p;
426
427 ima_filter_rule_init(nentry->lsm[i].type, Audit_equal,
428 nentry->lsm[i].args_p,
429 &nentry->lsm[i].rule,
430 gfp);
431 if (!nentry->lsm[i].rule)
432 pr_warn("rule for LSM \'%s\' is undefined\n",
433 nentry->lsm[i].args_p);
434 }
435 return nentry;
436 }
437
438 static int ima_lsm_update_rule(struct ima_rule_entry *entry)
439 {
440 int i;
441 struct ima_rule_entry *nentry;
442
443 nentry = ima_lsm_copy_rule(entry, GFP_KERNEL);
444 if (!nentry)
445 return -ENOMEM;
446
447 list_replace_rcu(&entry->list, &nentry->list);
448 synchronize_rcu();
449 /*
450 * ima_lsm_copy_rule() shallow copied all references, except for the
451 * LSM references, from entry to nentry so we only want to free the LSM
452 * references and the entry itself. All other memory references will now
453 * be owned by nentry.
454 */
455 for (i = 0; i < MAX_LSM_RULES; i++)
456 ima_filter_rule_free(entry->lsm[i].rule);
457 kfree(entry);
458
459 return 0;
460 }
461
462 static bool ima_rule_contains_lsm_cond(struct ima_rule_entry *entry)
463 {
464 int i;
465
466 for (i = 0; i < MAX_LSM_RULES; i++)
467 if (entry->lsm[i].args_p)
468 return true;
469
470 return false;
471 }
472
473 /*
474 * The LSM policy can be reloaded, leaving the IMA LSM based rules referring
475 * to the old, stale LSM policy. Update the IMA LSM based rules to reflect
476 * the reloaded LSM policy.
477 */
478 static void ima_lsm_update_rules(void)
479 {
480 struct ima_rule_entry *entry, *e;
481 int result;
482
483 list_for_each_entry_safe(entry, e, &ima_policy_rules, list) {
484 if (!ima_rule_contains_lsm_cond(entry))
485 continue;
486
487 result = ima_lsm_update_rule(entry);
488 if (result) {
489 pr_err("lsm rule update error %d\n", result);
490 return;
491 }
492 }
493 }
494
495 int ima_lsm_policy_change(struct notifier_block *nb, unsigned long event,
496 void *lsm_data)
497 {
498 if (event != LSM_POLICY_CHANGE)
499 return NOTIFY_DONE;
500
501 ima_lsm_update_rules();
502 return NOTIFY_OK;
503 }
504
505 /**
506 * ima_match_rule_data - determine whether func_data matches the policy rule
507 * @rule: a pointer to a rule
508 * @func_data: data to match against the measure rule data
509 * @cred: a pointer to a credentials structure for user validation
510 *
511 * Returns true if func_data matches one in the rule, false otherwise.
512 */
513 static bool ima_match_rule_data(struct ima_rule_entry *rule,
514 const char *func_data,
515 const struct cred *cred)
516 {
517 const struct ima_rule_opt_list *opt_list = NULL;
518 bool matched = false;
519 size_t i;
520
521 if ((rule->flags & IMA_UID) && !rule->uid_op(cred->uid, rule->uid))
522 return false;
523
524 switch (rule->func) {
525 case KEY_CHECK:
526 if (!rule->keyrings)
527 return true;
528
529 opt_list = rule->keyrings;
530 break;
531 case CRITICAL_DATA:
532 if (!rule->label)
533 return true;
534
535 opt_list = rule->label;
536 break;
537 default:
538 return false;
539 }
540
541 if (!func_data)
542 return false;
543
544 for (i = 0; i < opt_list->count; i++) {
545 if (!strcmp(opt_list->items[i], func_data)) {
546 matched = true;
547 break;
548 }
549 }
550
551 return matched;
552 }
553
554 /**
555 * ima_match_rules - determine whether an inode matches the policy rule.
556 * @rule: a pointer to a rule
557 * @idmap: idmap of the mount the inode was found from
558 * @inode: a pointer to an inode
559 * @cred: a pointer to a credentials structure for user validation
560 * @secid: the secid of the task to be validated
561 * @func: LIM hook identifier
562 * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC)
563 * @func_data: func specific data, may be NULL
564 *
565 * Returns true on rule match, false on failure.
566 */
567 static bool ima_match_rules(struct ima_rule_entry *rule,
568 struct mnt_idmap *idmap,
569 struct inode *inode, const struct cred *cred,
570 u32 secid, enum ima_hooks func, int mask,
571 const char *func_data)
572 {
573 int i;
574 bool result = false;
575 struct ima_rule_entry *lsm_rule = rule;
576 bool rule_reinitialized = false;
577
578 if ((rule->flags & IMA_FUNC) &&
579 (rule->func != func && func != POST_SETATTR))
580 return false;
581
582 switch (func) {
583 case KEY_CHECK:
584 case CRITICAL_DATA:
585 return ((rule->func == func) &&
586 ima_match_rule_data(rule, func_data, cred));
587 default:
588 break;
589 }
590
591 if ((rule->flags & IMA_MASK) &&
592 (rule->mask != mask && func != POST_SETATTR))
593 return false;
594 if ((rule->flags & IMA_INMASK) &&
595 (!(rule->mask & mask) && func != POST_SETATTR))
596 return false;
597 if ((rule->flags & IMA_FSMAGIC)
598 && rule->fsmagic != inode->i_sb->s_magic)
599 return false;
600 if ((rule->flags & IMA_FSNAME)
601 && strcmp(rule->fsname, inode->i_sb->s_type->name))
602 return false;
603 if ((rule->flags & IMA_FSUUID) &&
604 !uuid_equal(&rule->fsuuid, &inode->i_sb->s_uuid))
605 return false;
606 if ((rule->flags & IMA_UID) && !rule->uid_op(cred->uid, rule->uid))
607 return false;
608 if (rule->flags & IMA_EUID) {
609 if (has_capability_noaudit(current, CAP_SETUID)) {
610 if (!rule->uid_op(cred->euid, rule->uid)
611 && !rule->uid_op(cred->suid, rule->uid)
612 && !rule->uid_op(cred->uid, rule->uid))
613 return false;
614 } else if (!rule->uid_op(cred->euid, rule->uid))
615 return false;
616 }
617 if ((rule->flags & IMA_GID) && !rule->gid_op(cred->gid, rule->gid))
618 return false;
619 if (rule->flags & IMA_EGID) {
620 if (has_capability_noaudit(current, CAP_SETGID)) {
621 if (!rule->gid_op(cred->egid, rule->gid)
622 && !rule->gid_op(cred->sgid, rule->gid)
623 && !rule->gid_op(cred->gid, rule->gid))
624 return false;
625 } else if (!rule->gid_op(cred->egid, rule->gid))
626 return false;
627 }
628 if ((rule->flags & IMA_FOWNER) &&
629 !rule->fowner_op(i_uid_into_vfsuid(idmap, inode),
630 rule->fowner))
631 return false;
632 if ((rule->flags & IMA_FGROUP) &&
633 !rule->fgroup_op(i_gid_into_vfsgid(idmap, inode),
634 rule->fgroup))
635 return false;
636 for (i = 0; i < MAX_LSM_RULES; i++) {
637 int rc = 0;
638 u32 osid;
639
640 if (!lsm_rule->lsm[i].rule) {
641 if (!lsm_rule->lsm[i].args_p)
642 continue;
643 else
644 return false;
645 }
646
647 retry:
648 switch (i) {
649 case LSM_OBJ_USER:
650 case LSM_OBJ_ROLE:
651 case LSM_OBJ_TYPE:
652 security_inode_getsecid(inode, &osid);
653 rc = ima_filter_rule_match(osid, lsm_rule->lsm[i].type,
654 Audit_equal,
655 lsm_rule->lsm[i].rule);
656 break;
657 case LSM_SUBJ_USER:
658 case LSM_SUBJ_ROLE:
659 case LSM_SUBJ_TYPE:
660 rc = ima_filter_rule_match(secid, lsm_rule->lsm[i].type,
661 Audit_equal,
662 lsm_rule->lsm[i].rule);
663 break;
664 default:
665 break;
666 }
667
668 if (rc == -ESTALE && !rule_reinitialized) {
669 lsm_rule = ima_lsm_copy_rule(rule, GFP_ATOMIC);
670 if (lsm_rule) {
671 rule_reinitialized = true;
672 goto retry;
673 }
674 }
675 if (!rc) {
676 result = false;
677 goto out;
678 }
679 }
680 result = true;
681
682 out:
683 if (rule_reinitialized) {
684 for (i = 0; i < MAX_LSM_RULES; i++)
685 ima_filter_rule_free(lsm_rule->lsm[i].rule);
686 kfree(lsm_rule);
687 }
688 return result;
689 }
690
691 /*
692 * In addition to knowing that we need to appraise the file in general,
693 * we need to differentiate between calling hooks, for hook specific rules.
694 */
695 static int get_subaction(struct ima_rule_entry *rule, enum ima_hooks func)
696 {
697 if (!(rule->flags & IMA_FUNC))
698 return IMA_FILE_APPRAISE;
699
700 switch (func) {
701 case MMAP_CHECK:
702 case MMAP_CHECK_REQPROT:
703 return IMA_MMAP_APPRAISE;
704 case BPRM_CHECK:
705 return IMA_BPRM_APPRAISE;
706 case CREDS_CHECK:
707 return IMA_CREDS_APPRAISE;
708 case FILE_CHECK:
709 case POST_SETATTR:
710 return IMA_FILE_APPRAISE;
711 case MODULE_CHECK ... MAX_CHECK - 1:
712 default:
713 return IMA_READ_APPRAISE;
714 }
715 }
716
717 /**
718 * ima_match_policy - decision based on LSM and other conditions
719 * @idmap: idmap of the mount the inode was found from
720 * @inode: pointer to an inode for which the policy decision is being made
721 * @cred: pointer to a credentials structure for which the policy decision is
722 * being made
723 * @secid: LSM secid of the task to be validated
724 * @func: IMA hook identifier
725 * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC)
726 * @flags: IMA actions to consider (e.g. IMA_MEASURE | IMA_APPRAISE)
727 * @pcr: set the pcr to extend
728 * @template_desc: the template that should be used for this rule
729 * @func_data: func specific data, may be NULL
730 * @allowed_algos: allowlist of hash algorithms for the IMA xattr
731 *
732 * Measure decision based on func/mask/fsmagic and LSM(subj/obj/type)
733 * conditions.
734 *
735 * Since the IMA policy may be updated multiple times we need to lock the
736 * list when walking it. Reads are many orders of magnitude more numerous
737 * than writes so ima_match_policy() is classical RCU candidate.
738 */
739 int ima_match_policy(struct mnt_idmap *idmap, struct inode *inode,
740 const struct cred *cred, u32 secid, enum ima_hooks func,
741 int mask, int flags, int *pcr,
742 struct ima_template_desc **template_desc,
743 const char *func_data, unsigned int *allowed_algos)
744 {
745 struct ima_rule_entry *entry;
746 int action = 0, actmask = flags | (flags << 1);
747 struct list_head *ima_rules_tmp;
748
749 if (template_desc && !*template_desc)
750 *template_desc = ima_template_desc_current();
751
752 rcu_read_lock();
753 ima_rules_tmp = rcu_dereference(ima_rules);
754 list_for_each_entry_rcu(entry, ima_rules_tmp, list) {
755
756 if (!(entry->action & actmask))
757 continue;
758
759 if (!ima_match_rules(entry, idmap, inode, cred, secid,
760 func, mask, func_data))
761 continue;
762
763 action |= entry->flags & IMA_NONACTION_FLAGS;
764
765 action |= entry->action & IMA_DO_MASK;
766 if (entry->action & IMA_APPRAISE) {
767 action |= get_subaction(entry, func);
768 action &= ~IMA_HASH;
769 if (ima_fail_unverifiable_sigs)
770 action |= IMA_FAIL_UNVERIFIABLE_SIGS;
771
772 if (allowed_algos &&
773 entry->flags & IMA_VALIDATE_ALGOS)
774 *allowed_algos = entry->allowed_algos;
775 }
776
777 if (entry->action & IMA_DO_MASK)
778 actmask &= ~(entry->action | entry->action << 1);
779 else
780 actmask &= ~(entry->action | entry->action >> 1);
781
782 if ((pcr) && (entry->flags & IMA_PCR))
783 *pcr = entry->pcr;
784
785 if (template_desc && entry->template)
786 *template_desc = entry->template;
787
788 if (!actmask)
789 break;
790 }
791 rcu_read_unlock();
792
793 return action;
794 }
795
796 /**
797 * ima_update_policy_flags() - Update global IMA variables
798 *
799 * Update ima_policy_flag and ima_setxattr_allowed_hash_algorithms
800 * based on the currently loaded policy.
801 *
802 * With ima_policy_flag, the decision to short circuit out of a function
803 * or not call the function in the first place can be made earlier.
804 *
805 * With ima_setxattr_allowed_hash_algorithms, the policy can restrict the
806 * set of hash algorithms accepted when updating the security.ima xattr of
807 * a file.
808 *
809 * Context: called after a policy update and at system initialization.
810 */
811 void ima_update_policy_flags(void)
812 {
813 struct ima_rule_entry *entry;
814 int new_policy_flag = 0;
815 struct list_head *ima_rules_tmp;
816
817 rcu_read_lock();
818 ima_rules_tmp = rcu_dereference(ima_rules);
819 list_for_each_entry_rcu(entry, ima_rules_tmp, list) {
820 /*
821 * SETXATTR_CHECK rules do not implement a full policy check
822 * because rule checking would probably have an important
823 * performance impact on setxattr(). As a consequence, only one
824 * SETXATTR_CHECK can be active at a given time.
825 * Because we want to preserve that property, we set out to use
826 * atomic_cmpxchg. Either:
827 * - the atomic was non-zero: a setxattr hash policy is
828 * already enforced, we do nothing
829 * - the atomic was zero: no setxattr policy was set, enable
830 * the setxattr hash policy
831 */
832 if (entry->func == SETXATTR_CHECK) {
833 atomic_cmpxchg(&ima_setxattr_allowed_hash_algorithms,
834 0, entry->allowed_algos);
835 /* SETXATTR_CHECK doesn't impact ima_policy_flag */
836 continue;
837 }
838
839 if (entry->action & IMA_DO_MASK)
840 new_policy_flag |= entry->action;
841 }
842 rcu_read_unlock();
843
844 ima_appraise |= (build_ima_appraise | temp_ima_appraise);
845 if (!ima_appraise)
846 new_policy_flag &= ~IMA_APPRAISE;
847
848 ima_policy_flag = new_policy_flag;
849 }
850
851 static int ima_appraise_flag(enum ima_hooks func)
852 {
853 if (func == MODULE_CHECK)
854 return IMA_APPRAISE_MODULES;
855 else if (func == FIRMWARE_CHECK)
856 return IMA_APPRAISE_FIRMWARE;
857 else if (func == POLICY_CHECK)
858 return IMA_APPRAISE_POLICY;
859 else if (func == KEXEC_KERNEL_CHECK)
860 return IMA_APPRAISE_KEXEC;
861 return 0;
862 }
863
864 static void add_rules(struct ima_rule_entry *entries, int count,
865 enum policy_rule_list policy_rule)
866 {
867 int i = 0;
868
869 for (i = 0; i < count; i++) {
870 struct ima_rule_entry *entry;
871
872 if (policy_rule & IMA_DEFAULT_POLICY)
873 list_add_tail(&entries[i].list, &ima_default_rules);
874
875 if (policy_rule & IMA_CUSTOM_POLICY) {
876 entry = kmemdup(&entries[i], sizeof(*entry),
877 GFP_KERNEL);
878 if (!entry)
879 continue;
880
881 list_add_tail(&entry->list, &ima_policy_rules);
882 }
883 if (entries[i].action == APPRAISE) {
884 if (entries != build_appraise_rules)
885 temp_ima_appraise |=
886 ima_appraise_flag(entries[i].func);
887 else
888 build_ima_appraise |=
889 ima_appraise_flag(entries[i].func);
890 }
891 }
892 }
893
894 static int ima_parse_rule(char *rule, struct ima_rule_entry *entry);
895
896 static int __init ima_init_arch_policy(void)
897 {
898 const char * const *arch_rules;
899 const char * const *rules;
900 int arch_entries = 0;
901 int i = 0;
902
903 arch_rules = arch_get_ima_policy();
904 if (!arch_rules)
905 return arch_entries;
906
907 /* Get number of rules */
908 for (rules = arch_rules; *rules != NULL; rules++)
909 arch_entries++;
910
911 arch_policy_entry = kcalloc(arch_entries + 1,
912 sizeof(*arch_policy_entry), GFP_KERNEL);
913 if (!arch_policy_entry)
914 return 0;
915
916 /* Convert each policy string rules to struct ima_rule_entry format */
917 for (rules = arch_rules, i = 0; *rules != NULL; rules++) {
918 char rule[255];
919 int result;
920
921 result = strscpy(rule, *rules, sizeof(rule));
922
923 INIT_LIST_HEAD(&arch_policy_entry[i].list);
924 result = ima_parse_rule(rule, &arch_policy_entry[i]);
925 if (result) {
926 pr_warn("Skipping unknown architecture policy rule: %s\n",
927 rule);
928 memset(&arch_policy_entry[i], 0,
929 sizeof(*arch_policy_entry));
930 continue;
931 }
932 i++;
933 }
934 return i;
935 }
936
937 /**
938 * ima_init_policy - initialize the default measure rules.
939 *
940 * ima_rules points to either the ima_default_rules or the new ima_policy_rules.
941 */
942 void __init ima_init_policy(void)
943 {
944 int build_appraise_entries, arch_entries;
945
946 /* if !ima_policy, we load NO default rules */
947 if (ima_policy)
948 add_rules(dont_measure_rules, ARRAY_SIZE(dont_measure_rules),
949 IMA_DEFAULT_POLICY);
950
951 switch (ima_policy) {
952 case ORIGINAL_TCB:
953 add_rules(original_measurement_rules,
954 ARRAY_SIZE(original_measurement_rules),
955 IMA_DEFAULT_POLICY);
956 break;
957 case DEFAULT_TCB:
958 add_rules(default_measurement_rules,
959 ARRAY_SIZE(default_measurement_rules),
960 IMA_DEFAULT_POLICY);
961 break;
962 default:
963 break;
964 }
965
966 /*
967 * Based on runtime secure boot flags, insert arch specific measurement
968 * and appraise rules requiring file signatures for both the initial
969 * and custom policies, prior to other appraise rules.
970 * (Highest priority)
971 */
972 arch_entries = ima_init_arch_policy();
973 if (!arch_entries)
974 pr_info("No architecture policies found\n");
975 else
976 add_rules(arch_policy_entry, arch_entries,
977 IMA_DEFAULT_POLICY | IMA_CUSTOM_POLICY);
978
979 /*
980 * Insert the builtin "secure_boot" policy rules requiring file
981 * signatures, prior to other appraise rules.
982 */
983 if (ima_use_secure_boot)
984 add_rules(secure_boot_rules, ARRAY_SIZE(secure_boot_rules),
985 IMA_DEFAULT_POLICY);
986
987 /*
988 * Insert the build time appraise rules requiring file signatures
989 * for both the initial and custom policies, prior to other appraise
990 * rules. As the secure boot rules includes all of the build time
991 * rules, include either one or the other set of rules, but not both.
992 */
993 build_appraise_entries = ARRAY_SIZE(build_appraise_rules);
994 if (build_appraise_entries) {
995 if (ima_use_secure_boot)
996 add_rules(build_appraise_rules, build_appraise_entries,
997 IMA_CUSTOM_POLICY);
998 else
999 add_rules(build_appraise_rules, build_appraise_entries,
1000 IMA_DEFAULT_POLICY | IMA_CUSTOM_POLICY);
1001 }
1002
1003 if (ima_use_appraise_tcb)
1004 add_rules(default_appraise_rules,
1005 ARRAY_SIZE(default_appraise_rules),
1006 IMA_DEFAULT_POLICY);
1007
1008 if (ima_use_critical_data)
1009 add_rules(critical_data_rules,
1010 ARRAY_SIZE(critical_data_rules),
1011 IMA_DEFAULT_POLICY);
1012
1013 atomic_set(&ima_setxattr_allowed_hash_algorithms, 0);
1014
1015 ima_update_policy_flags();
1016 }
1017
1018 /* Make sure we have a valid policy, at least containing some rules. */
1019 int ima_check_policy(void)
1020 {
1021 if (list_empty(&ima_temp_rules))
1022 return -EINVAL;
1023 return 0;
1024 }
1025
1026 /**
1027 * ima_update_policy - update default_rules with new measure rules
1028 *
1029 * Called on file .release to update the default rules with a complete new
1030 * policy. What we do here is to splice ima_policy_rules and ima_temp_rules so
1031 * they make a queue. The policy may be updated multiple times and this is the
1032 * RCU updater.
1033 *
1034 * Policy rules are never deleted so ima_policy_flag gets zeroed only once when
1035 * we switch from the default policy to user defined.
1036 */
1037 void ima_update_policy(void)
1038 {
1039 struct list_head *policy = &ima_policy_rules;
1040
1041 list_splice_tail_init_rcu(&ima_temp_rules, policy, synchronize_rcu);
1042
1043 if (ima_rules != (struct list_head __rcu *)policy) {
1044 ima_policy_flag = 0;
1045
1046 rcu_assign_pointer(ima_rules, policy);
1047 /*
1048 * IMA architecture specific policy rules are specified
1049 * as strings and converted to an array of ima_entry_rules
1050 * on boot. After loading a custom policy, free the
1051 * architecture specific rules stored as an array.
1052 */
1053 kfree(arch_policy_entry);
1054 }
1055 ima_update_policy_flags();
1056
1057 /* Custom IMA policy has been loaded */
1058 ima_process_queued_keys();
1059 }
1060
1061 /* Keep the enumeration in sync with the policy_tokens! */
1062 enum policy_opt {
1063 Opt_measure, Opt_dont_measure,
1064 Opt_appraise, Opt_dont_appraise,
1065 Opt_audit, Opt_hash, Opt_dont_hash,
1066 Opt_obj_user, Opt_obj_role, Opt_obj_type,
1067 Opt_subj_user, Opt_subj_role, Opt_subj_type,
1068 Opt_func, Opt_mask, Opt_fsmagic, Opt_fsname, Opt_fsuuid,
1069 Opt_uid_eq, Opt_euid_eq, Opt_gid_eq, Opt_egid_eq,
1070 Opt_fowner_eq, Opt_fgroup_eq,
1071 Opt_uid_gt, Opt_euid_gt, Opt_gid_gt, Opt_egid_gt,
1072 Opt_fowner_gt, Opt_fgroup_gt,
1073 Opt_uid_lt, Opt_euid_lt, Opt_gid_lt, Opt_egid_lt,
1074 Opt_fowner_lt, Opt_fgroup_lt,
1075 Opt_digest_type,
1076 Opt_appraise_type, Opt_appraise_flag, Opt_appraise_algos,
1077 Opt_permit_directio, Opt_pcr, Opt_template, Opt_keyrings,
1078 Opt_label, Opt_err
1079 };
1080
1081 static const match_table_t policy_tokens = {
1082 {Opt_measure, "measure"},
1083 {Opt_dont_measure, "dont_measure"},
1084 {Opt_appraise, "appraise"},
1085 {Opt_dont_appraise, "dont_appraise"},
1086 {Opt_audit, "audit"},
1087 {Opt_hash, "hash"},
1088 {Opt_dont_hash, "dont_hash"},
1089 {Opt_obj_user, "obj_user=%s"},
1090 {Opt_obj_role, "obj_role=%s"},
1091 {Opt_obj_type, "obj_type=%s"},
1092 {Opt_subj_user, "subj_user=%s"},
1093 {Opt_subj_role, "subj_role=%s"},
1094 {Opt_subj_type, "subj_type=%s"},
1095 {Opt_func, "func=%s"},
1096 {Opt_mask, "mask=%s"},
1097 {Opt_fsmagic, "fsmagic=%s"},
1098 {Opt_fsname, "fsname=%s"},
1099 {Opt_fsuuid, "fsuuid=%s"},
1100 {Opt_uid_eq, "uid=%s"},
1101 {Opt_euid_eq, "euid=%s"},
1102 {Opt_gid_eq, "gid=%s"},
1103 {Opt_egid_eq, "egid=%s"},
1104 {Opt_fowner_eq, "fowner=%s"},
1105 {Opt_fgroup_eq, "fgroup=%s"},
1106 {Opt_uid_gt, "uid>%s"},
1107 {Opt_euid_gt, "euid>%s"},
1108 {Opt_gid_gt, "gid>%s"},
1109 {Opt_egid_gt, "egid>%s"},
1110 {Opt_fowner_gt, "fowner>%s"},
1111 {Opt_fgroup_gt, "fgroup>%s"},
1112 {Opt_uid_lt, "uid<%s"},
1113 {Opt_euid_lt, "euid<%s"},
1114 {Opt_gid_lt, "gid<%s"},
1115 {Opt_egid_lt, "egid<%s"},
1116 {Opt_fowner_lt, "fowner<%s"},
1117 {Opt_fgroup_lt, "fgroup<%s"},
1118 {Opt_digest_type, "digest_type=%s"},
1119 {Opt_appraise_type, "appraise_type=%s"},
1120 {Opt_appraise_flag, "appraise_flag=%s"},
1121 {Opt_appraise_algos, "appraise_algos=%s"},
1122 {Opt_permit_directio, "permit_directio"},
1123 {Opt_pcr, "pcr=%s"},
1124 {Opt_template, "template=%s"},
1125 {Opt_keyrings, "keyrings=%s"},
1126 {Opt_label, "label=%s"},
1127 {Opt_err, NULL}
1128 };
1129
1130 static int ima_lsm_rule_init(struct ima_rule_entry *entry,
1131 substring_t *args, int lsm_rule, int audit_type)
1132 {
1133 int result;
1134
1135 if (entry->lsm[lsm_rule].rule)
1136 return -EINVAL;
1137
1138 entry->lsm[lsm_rule].args_p = match_strdup(args);
1139 if (!entry->lsm[lsm_rule].args_p)
1140 return -ENOMEM;
1141
1142 entry->lsm[lsm_rule].type = audit_type;
1143 result = ima_filter_rule_init(entry->lsm[lsm_rule].type, Audit_equal,
1144 entry->lsm[lsm_rule].args_p,
1145 &entry->lsm[lsm_rule].rule,
1146 GFP_KERNEL);
1147 if (!entry->lsm[lsm_rule].rule) {
1148 pr_warn("rule for LSM \'%s\' is undefined\n",
1149 entry->lsm[lsm_rule].args_p);
1150
1151 if (ima_rules == (struct list_head __rcu *)(&ima_default_rules)) {
1152 kfree(entry->lsm[lsm_rule].args_p);
1153 entry->lsm[lsm_rule].args_p = NULL;
1154 result = -EINVAL;
1155 } else
1156 result = 0;
1157 }
1158
1159 return result;
1160 }
1161
1162 static void ima_log_string_op(struct audit_buffer *ab, char *key, char *value,
1163 enum policy_opt rule_operator)
1164 {
1165 if (!ab)
1166 return;
1167
1168 switch (rule_operator) {
1169 case Opt_uid_gt:
1170 case Opt_euid_gt:
1171 case Opt_gid_gt:
1172 case Opt_egid_gt:
1173 case Opt_fowner_gt:
1174 case Opt_fgroup_gt:
1175 audit_log_format(ab, "%s>", key);
1176 break;
1177 case Opt_uid_lt:
1178 case Opt_euid_lt:
1179 case Opt_gid_lt:
1180 case Opt_egid_lt:
1181 case Opt_fowner_lt:
1182 case Opt_fgroup_lt:
1183 audit_log_format(ab, "%s<", key);
1184 break;
1185 default:
1186 audit_log_format(ab, "%s=", key);
1187 }
1188 audit_log_format(ab, "%s ", value);
1189 }
1190 static void ima_log_string(struct audit_buffer *ab, char *key, char *value)
1191 {
1192 ima_log_string_op(ab, key, value, Opt_err);
1193 }
1194
1195 /*
1196 * Validating the appended signature included in the measurement list requires
1197 * the file hash calculated without the appended signature (i.e., the 'd-modsig'
1198 * field). Therefore, notify the user if they have the 'modsig' field but not
1199 * the 'd-modsig' field in the template.
1200 */
1201 static void check_template_modsig(const struct ima_template_desc *template)
1202 {
1203 #define MSG "template with 'modsig' field also needs 'd-modsig' field\n"
1204 bool has_modsig, has_dmodsig;
1205 static bool checked;
1206 int i;
1207
1208 /* We only need to notify the user once. */
1209 if (checked)
1210 return;
1211
1212 has_modsig = has_dmodsig = false;
1213 for (i = 0; i < template->num_fields; i++) {
1214 if (!strcmp(template->fields[i]->field_id, "modsig"))
1215 has_modsig = true;
1216 else if (!strcmp(template->fields[i]->field_id, "d-modsig"))
1217 has_dmodsig = true;
1218 }
1219
1220 if (has_modsig && !has_dmodsig)
1221 pr_notice(MSG);
1222
1223 checked = true;
1224 #undef MSG
1225 }
1226
1227 /*
1228 * Warn if the template does not contain the given field.
1229 */
1230 static void check_template_field(const struct ima_template_desc *template,
1231 const char *field, const char *msg)
1232 {
1233 int i;
1234
1235 for (i = 0; i < template->num_fields; i++)
1236 if (!strcmp(template->fields[i]->field_id, field))
1237 return;
1238
1239 pr_notice_once("%s", msg);
1240 }
1241
1242 static bool ima_validate_rule(struct ima_rule_entry *entry)
1243 {
1244 /* Ensure that the action is set and is compatible with the flags */
1245 if (entry->action == UNKNOWN)
1246 return false;
1247
1248 if (entry->action != MEASURE && entry->flags & IMA_PCR)
1249 return false;
1250
1251 if (entry->action != APPRAISE &&
1252 entry->flags & (IMA_DIGSIG_REQUIRED | IMA_MODSIG_ALLOWED |
1253 IMA_CHECK_BLACKLIST | IMA_VALIDATE_ALGOS))
1254 return false;
1255
1256 /*
1257 * The IMA_FUNC bit must be set if and only if there's a valid hook
1258 * function specified, and vice versa. Enforcing this property allows
1259 * for the NONE case below to validate a rule without an explicit hook
1260 * function.
1261 */
1262 if (((entry->flags & IMA_FUNC) && entry->func == NONE) ||
1263 (!(entry->flags & IMA_FUNC) && entry->func != NONE))
1264 return false;
1265
1266 /*
1267 * Ensure that the hook function is compatible with the other
1268 * components of the rule
1269 */
1270 switch (entry->func) {
1271 case NONE:
1272 case FILE_CHECK:
1273 case MMAP_CHECK:
1274 case MMAP_CHECK_REQPROT:
1275 case BPRM_CHECK:
1276 case CREDS_CHECK:
1277 case POST_SETATTR:
1278 case FIRMWARE_CHECK:
1279 case POLICY_CHECK:
1280 if (entry->flags & ~(IMA_FUNC | IMA_MASK | IMA_FSMAGIC |
1281 IMA_UID | IMA_FOWNER | IMA_FSUUID |
1282 IMA_INMASK | IMA_EUID | IMA_PCR |
1283 IMA_FSNAME | IMA_GID | IMA_EGID |
1284 IMA_FGROUP | IMA_DIGSIG_REQUIRED |
1285 IMA_PERMIT_DIRECTIO | IMA_VALIDATE_ALGOS |
1286 IMA_CHECK_BLACKLIST | IMA_VERITY_REQUIRED))
1287 return false;
1288
1289 break;
1290 case MODULE_CHECK:
1291 case KEXEC_KERNEL_CHECK:
1292 case KEXEC_INITRAMFS_CHECK:
1293 if (entry->flags & ~(IMA_FUNC | IMA_MASK | IMA_FSMAGIC |
1294 IMA_UID | IMA_FOWNER | IMA_FSUUID |
1295 IMA_INMASK | IMA_EUID | IMA_PCR |
1296 IMA_FSNAME | IMA_GID | IMA_EGID |
1297 IMA_FGROUP | IMA_DIGSIG_REQUIRED |
1298 IMA_PERMIT_DIRECTIO | IMA_MODSIG_ALLOWED |
1299 IMA_CHECK_BLACKLIST | IMA_VALIDATE_ALGOS))
1300 return false;
1301
1302 break;
1303 case KEXEC_CMDLINE:
1304 if (entry->action & ~(MEASURE | DONT_MEASURE))
1305 return false;
1306
1307 if (entry->flags & ~(IMA_FUNC | IMA_FSMAGIC | IMA_UID |
1308 IMA_FOWNER | IMA_FSUUID | IMA_EUID |
1309 IMA_PCR | IMA_FSNAME | IMA_GID | IMA_EGID |
1310 IMA_FGROUP))
1311 return false;
1312
1313 break;
1314 case KEY_CHECK:
1315 if (entry->action & ~(MEASURE | DONT_MEASURE))
1316 return false;
1317
1318 if (entry->flags & ~(IMA_FUNC | IMA_UID | IMA_GID | IMA_PCR |
1319 IMA_KEYRINGS))
1320 return false;
1321
1322 if (ima_rule_contains_lsm_cond(entry))
1323 return false;
1324
1325 break;
1326 case CRITICAL_DATA:
1327 if (entry->action & ~(MEASURE | DONT_MEASURE))
1328 return false;
1329
1330 if (entry->flags & ~(IMA_FUNC | IMA_UID | IMA_GID | IMA_PCR |
1331 IMA_LABEL))
1332 return false;
1333
1334 if (ima_rule_contains_lsm_cond(entry))
1335 return false;
1336
1337 break;
1338 case SETXATTR_CHECK:
1339 /* any action other than APPRAISE is unsupported */
1340 if (entry->action != APPRAISE)
1341 return false;
1342
1343 /* SETXATTR_CHECK requires an appraise_algos parameter */
1344 if (!(entry->flags & IMA_VALIDATE_ALGOS))
1345 return false;
1346
1347 /*
1348 * full policies are not supported, they would have too
1349 * much of a performance impact
1350 */
1351 if (entry->flags & ~(IMA_FUNC | IMA_VALIDATE_ALGOS))
1352 return false;
1353
1354 break;
1355 default:
1356 return false;
1357 }
1358
1359 /* Ensure that combinations of flags are compatible with each other */
1360 if (entry->flags & IMA_CHECK_BLACKLIST &&
1361 !(entry->flags & IMA_DIGSIG_REQUIRED))
1362 return false;
1363
1364 /*
1365 * Unlike for regular IMA 'appraise' policy rules where security.ima
1366 * xattr may contain either a file hash or signature, the security.ima
1367 * xattr for fsverity must contain a file signature (sigv3). Ensure
1368 * that 'appraise' rules for fsverity require file signatures by
1369 * checking the IMA_DIGSIG_REQUIRED flag is set.
1370 */
1371 if (entry->action == APPRAISE &&
1372 (entry->flags & IMA_VERITY_REQUIRED) &&
1373 !(entry->flags & IMA_DIGSIG_REQUIRED))
1374 return false;
1375
1376 return true;
1377 }
1378
1379 static unsigned int ima_parse_appraise_algos(char *arg)
1380 {
1381 unsigned int res = 0;
1382 int idx;
1383 char *token;
1384
1385 while ((token = strsep(&arg, ",")) != NULL) {
1386 idx = match_string(hash_algo_name, HASH_ALGO__LAST, token);
1387
1388 if (idx < 0) {
1389 pr_err("unknown hash algorithm \"%s\"",
1390 token);
1391 return 0;
1392 }
1393
1394 if (!crypto_has_alg(hash_algo_name[idx], 0, 0)) {
1395 pr_err("unavailable hash algorithm \"%s\", check your kernel configuration",
1396 token);
1397 return 0;
1398 }
1399
1400 /* Add the hash algorithm to the 'allowed' bitfield */
1401 res |= (1U << idx);
1402 }
1403
1404 return res;
1405 }
1406
1407 static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
1408 {
1409 struct audit_buffer *ab;
1410 char *from;
1411 char *p;
1412 bool eid_token; /* either euid or egid */
1413 struct ima_template_desc *template_desc;
1414 int result = 0;
1415
1416 ab = integrity_audit_log_start(audit_context(), GFP_KERNEL,
1417 AUDIT_INTEGRITY_POLICY_RULE);
1418
1419 entry->uid = INVALID_UID;
1420 entry->gid = INVALID_GID;
1421 entry->fowner = INVALID_UID;
1422 entry->fgroup = INVALID_GID;
1423 entry->uid_op = &uid_eq;
1424 entry->gid_op = &gid_eq;
1425 entry->fowner_op = &vfsuid_eq_kuid;
1426 entry->fgroup_op = &vfsgid_eq_kgid;
1427 entry->action = UNKNOWN;
1428 while ((p = strsep(&rule, " \t")) != NULL) {
1429 substring_t args[MAX_OPT_ARGS];
1430 int token;
1431 unsigned long lnum;
1432
1433 if (result < 0)
1434 break;
1435 if ((*p == '\0') || (*p == ' ') || (*p == '\t'))
1436 continue;
1437 token = match_token(p, policy_tokens, args);
1438 switch (token) {
1439 case Opt_measure:
1440 ima_log_string(ab, "action", "measure");
1441
1442 if (entry->action != UNKNOWN)
1443 result = -EINVAL;
1444
1445 entry->action = MEASURE;
1446 break;
1447 case Opt_dont_measure:
1448 ima_log_string(ab, "action", "dont_measure");
1449
1450 if (entry->action != UNKNOWN)
1451 result = -EINVAL;
1452
1453 entry->action = DONT_MEASURE;
1454 break;
1455 case Opt_appraise:
1456 ima_log_string(ab, "action", "appraise");
1457
1458 if (entry->action != UNKNOWN)
1459 result = -EINVAL;
1460
1461 entry->action = APPRAISE;
1462 break;
1463 case Opt_dont_appraise:
1464 ima_log_string(ab, "action", "dont_appraise");
1465
1466 if (entry->action != UNKNOWN)
1467 result = -EINVAL;
1468
1469 entry->action = DONT_APPRAISE;
1470 break;
1471 case Opt_audit:
1472 ima_log_string(ab, "action", "audit");
1473
1474 if (entry->action != UNKNOWN)
1475 result = -EINVAL;
1476
1477 entry->action = AUDIT;
1478 break;
1479 case Opt_hash:
1480 ima_log_string(ab, "action", "hash");
1481
1482 if (entry->action != UNKNOWN)
1483 result = -EINVAL;
1484
1485 entry->action = HASH;
1486 break;
1487 case Opt_dont_hash:
1488 ima_log_string(ab, "action", "dont_hash");
1489
1490 if (entry->action != UNKNOWN)
1491 result = -EINVAL;
1492
1493 entry->action = DONT_HASH;
1494 break;
1495 case Opt_func:
1496 ima_log_string(ab, "func", args[0].from);
1497
1498 if (entry->func)
1499 result = -EINVAL;
1500
1501 if (strcmp(args[0].from, "FILE_CHECK") == 0)
1502 entry->func = FILE_CHECK;
1503 /* PATH_CHECK is for backwards compat */
1504 else if (strcmp(args[0].from, "PATH_CHECK") == 0)
1505 entry->func = FILE_CHECK;
1506 else if (strcmp(args[0].from, "MODULE_CHECK") == 0)
1507 entry->func = MODULE_CHECK;
1508 else if (strcmp(args[0].from, "FIRMWARE_CHECK") == 0)
1509 entry->func = FIRMWARE_CHECK;
1510 else if ((strcmp(args[0].from, "FILE_MMAP") == 0)
1511 || (strcmp(args[0].from, "MMAP_CHECK") == 0))
1512 entry->func = MMAP_CHECK;
1513 else if ((strcmp(args[0].from, "MMAP_CHECK_REQPROT") == 0))
1514 entry->func = MMAP_CHECK_REQPROT;
1515 else if (strcmp(args[0].from, "BPRM_CHECK") == 0)
1516 entry->func = BPRM_CHECK;
1517 else if (strcmp(args[0].from, "CREDS_CHECK") == 0)
1518 entry->func = CREDS_CHECK;
1519 else if (strcmp(args[0].from, "KEXEC_KERNEL_CHECK") ==
1520 0)
1521 entry->func = KEXEC_KERNEL_CHECK;
1522 else if (strcmp(args[0].from, "KEXEC_INITRAMFS_CHECK")
1523 == 0)
1524 entry->func = KEXEC_INITRAMFS_CHECK;
1525 else if (strcmp(args[0].from, "POLICY_CHECK") == 0)
1526 entry->func = POLICY_CHECK;
1527 else if (strcmp(args[0].from, "KEXEC_CMDLINE") == 0)
1528 entry->func = KEXEC_CMDLINE;
1529 else if (IS_ENABLED(CONFIG_IMA_MEASURE_ASYMMETRIC_KEYS) &&
1530 strcmp(args[0].from, "KEY_CHECK") == 0)
1531 entry->func = KEY_CHECK;
1532 else if (strcmp(args[0].from, "CRITICAL_DATA") == 0)
1533 entry->func = CRITICAL_DATA;
1534 else if (strcmp(args[0].from, "SETXATTR_CHECK") == 0)
1535 entry->func = SETXATTR_CHECK;
1536 else
1537 result = -EINVAL;
1538 if (!result)
1539 entry->flags |= IMA_FUNC;
1540 break;
1541 case Opt_mask:
1542 ima_log_string(ab, "mask", args[0].from);
1543
1544 if (entry->mask)
1545 result = -EINVAL;
1546
1547 from = args[0].from;
1548 if (*from == '^')
1549 from++;
1550
1551 if ((strcmp(from, "MAY_EXEC")) == 0)
1552 entry->mask = MAY_EXEC;
1553 else if (strcmp(from, "MAY_WRITE") == 0)
1554 entry->mask = MAY_WRITE;
1555 else if (strcmp(from, "MAY_READ") == 0)
1556 entry->mask = MAY_READ;
1557 else if (strcmp(from, "MAY_APPEND") == 0)
1558 entry->mask = MAY_APPEND;
1559 else
1560 result = -EINVAL;
1561 if (!result)
1562 entry->flags |= (*args[0].from == '^')
1563 ? IMA_INMASK : IMA_MASK;
1564 break;
1565 case Opt_fsmagic:
1566 ima_log_string(ab, "fsmagic", args[0].from);
1567
1568 if (entry->fsmagic) {
1569 result = -EINVAL;
1570 break;
1571 }
1572
1573 result = kstrtoul(args[0].from, 16, &entry->fsmagic);
1574 if (!result)
1575 entry->flags |= IMA_FSMAGIC;
1576 break;
1577 case Opt_fsname:
1578 ima_log_string(ab, "fsname", args[0].from);
1579
1580 entry->fsname = kstrdup(args[0].from, GFP_KERNEL);
1581 if (!entry->fsname) {
1582 result = -ENOMEM;
1583 break;
1584 }
1585 result = 0;
1586 entry->flags |= IMA_FSNAME;
1587 break;
1588 case Opt_keyrings:
1589 ima_log_string(ab, "keyrings", args[0].from);
1590
1591 if (!IS_ENABLED(CONFIG_IMA_MEASURE_ASYMMETRIC_KEYS) ||
1592 entry->keyrings) {
1593 result = -EINVAL;
1594 break;
1595 }
1596
1597 entry->keyrings = ima_alloc_rule_opt_list(args);
1598 if (IS_ERR(entry->keyrings)) {
1599 result = PTR_ERR(entry->keyrings);
1600 entry->keyrings = NULL;
1601 break;
1602 }
1603
1604 entry->flags |= IMA_KEYRINGS;
1605 break;
1606 case Opt_label:
1607 ima_log_string(ab, "label", args[0].from);
1608
1609 if (entry->label) {
1610 result = -EINVAL;
1611 break;
1612 }
1613
1614 entry->label = ima_alloc_rule_opt_list(args);
1615 if (IS_ERR(entry->label)) {
1616 result = PTR_ERR(entry->label);
1617 entry->label = NULL;
1618 break;
1619 }
1620
1621 entry->flags |= IMA_LABEL;
1622 break;
1623 case Opt_fsuuid:
1624 ima_log_string(ab, "fsuuid", args[0].from);
1625
1626 if (!uuid_is_null(&entry->fsuuid)) {
1627 result = -EINVAL;
1628 break;
1629 }
1630
1631 result = uuid_parse(args[0].from, &entry->fsuuid);
1632 if (!result)
1633 entry->flags |= IMA_FSUUID;
1634 break;
1635 case Opt_uid_gt:
1636 case Opt_euid_gt:
1637 entry->uid_op = &uid_gt;
1638 fallthrough;
1639 case Opt_uid_lt:
1640 case Opt_euid_lt:
1641 if ((token == Opt_uid_lt) || (token == Opt_euid_lt))
1642 entry->uid_op = &uid_lt;
1643 fallthrough;
1644 case Opt_uid_eq:
1645 case Opt_euid_eq:
1646 eid_token = (token == Opt_euid_eq) ||
1647 (token == Opt_euid_gt) ||
1648 (token == Opt_euid_lt);
1649
1650 ima_log_string_op(ab, eid_token ? "euid" : "uid",
1651 args[0].from, token);
1652
1653 if (uid_valid(entry->uid)) {
1654 result = -EINVAL;
1655 break;
1656 }
1657
1658 result = kstrtoul(args[0].from, 10, &lnum);
1659 if (!result) {
1660 entry->uid = make_kuid(current_user_ns(),
1661 (uid_t) lnum);
1662 if (!uid_valid(entry->uid) ||
1663 (uid_t)lnum != lnum)
1664 result = -EINVAL;
1665 else
1666 entry->flags |= eid_token
1667 ? IMA_EUID : IMA_UID;
1668 }
1669 break;
1670 case Opt_gid_gt:
1671 case Opt_egid_gt:
1672 entry->gid_op = &gid_gt;
1673 fallthrough;
1674 case Opt_gid_lt:
1675 case Opt_egid_lt:
1676 if ((token == Opt_gid_lt) || (token == Opt_egid_lt))
1677 entry->gid_op = &gid_lt;
1678 fallthrough;
1679 case Opt_gid_eq:
1680 case Opt_egid_eq:
1681 eid_token = (token == Opt_egid_eq) ||
1682 (token == Opt_egid_gt) ||
1683 (token == Opt_egid_lt);
1684
1685 ima_log_string_op(ab, eid_token ? "egid" : "gid",
1686 args[0].from, token);
1687
1688 if (gid_valid(entry->gid)) {
1689 result = -EINVAL;
1690 break;
1691 }
1692
1693 result = kstrtoul(args[0].from, 10, &lnum);
1694 if (!result) {
1695 entry->gid = make_kgid(current_user_ns(),
1696 (gid_t)lnum);
1697 if (!gid_valid(entry->gid) ||
1698 (((gid_t)lnum) != lnum))
1699 result = -EINVAL;
1700 else
1701 entry->flags |= eid_token
1702 ? IMA_EGID : IMA_GID;
1703 }
1704 break;
1705 case Opt_fowner_gt:
1706 entry->fowner_op = &vfsuid_gt_kuid;
1707 fallthrough;
1708 case Opt_fowner_lt:
1709 if (token == Opt_fowner_lt)
1710 entry->fowner_op = &vfsuid_lt_kuid;
1711 fallthrough;
1712 case Opt_fowner_eq:
1713 ima_log_string_op(ab, "fowner", args[0].from, token);
1714
1715 if (uid_valid(entry->fowner)) {
1716 result = -EINVAL;
1717 break;
1718 }
1719
1720 result = kstrtoul(args[0].from, 10, &lnum);
1721 if (!result) {
1722 entry->fowner = make_kuid(current_user_ns(),
1723 (uid_t)lnum);
1724 if (!uid_valid(entry->fowner) ||
1725 (((uid_t)lnum) != lnum))
1726 result = -EINVAL;
1727 else
1728 entry->flags |= IMA_FOWNER;
1729 }
1730 break;
1731 case Opt_fgroup_gt:
1732 entry->fgroup_op = &vfsgid_gt_kgid;
1733 fallthrough;
1734 case Opt_fgroup_lt:
1735 if (token == Opt_fgroup_lt)
1736 entry->fgroup_op = &vfsgid_lt_kgid;
1737 fallthrough;
1738 case Opt_fgroup_eq:
1739 ima_log_string_op(ab, "fgroup", args[0].from, token);
1740
1741 if (gid_valid(entry->fgroup)) {
1742 result = -EINVAL;
1743 break;
1744 }
1745
1746 result = kstrtoul(args[0].from, 10, &lnum);
1747 if (!result) {
1748 entry->fgroup = make_kgid(current_user_ns(),
1749 (gid_t)lnum);
1750 if (!gid_valid(entry->fgroup) ||
1751 (((gid_t)lnum) != lnum))
1752 result = -EINVAL;
1753 else
1754 entry->flags |= IMA_FGROUP;
1755 }
1756 break;
1757 case Opt_obj_user:
1758 ima_log_string(ab, "obj_user", args[0].from);
1759 result = ima_lsm_rule_init(entry, args,
1760 LSM_OBJ_USER,
1761 AUDIT_OBJ_USER);
1762 break;
1763 case Opt_obj_role:
1764 ima_log_string(ab, "obj_role", args[0].from);
1765 result = ima_lsm_rule_init(entry, args,
1766 LSM_OBJ_ROLE,
1767 AUDIT_OBJ_ROLE);
1768 break;
1769 case Opt_obj_type:
1770 ima_log_string(ab, "obj_type", args[0].from);
1771 result = ima_lsm_rule_init(entry, args,
1772 LSM_OBJ_TYPE,
1773 AUDIT_OBJ_TYPE);
1774 break;
1775 case Opt_subj_user:
1776 ima_log_string(ab, "subj_user", args[0].from);
1777 result = ima_lsm_rule_init(entry, args,
1778 LSM_SUBJ_USER,
1779 AUDIT_SUBJ_USER);
1780 break;
1781 case Opt_subj_role:
1782 ima_log_string(ab, "subj_role", args[0].from);
1783 result = ima_lsm_rule_init(entry, args,
1784 LSM_SUBJ_ROLE,
1785 AUDIT_SUBJ_ROLE);
1786 break;
1787 case Opt_subj_type:
1788 ima_log_string(ab, "subj_type", args[0].from);
1789 result = ima_lsm_rule_init(entry, args,
1790 LSM_SUBJ_TYPE,
1791 AUDIT_SUBJ_TYPE);
1792 break;
1793 case Opt_digest_type:
1794 ima_log_string(ab, "digest_type", args[0].from);
1795 if (entry->flags & IMA_DIGSIG_REQUIRED)
1796 result = -EINVAL;
1797 else if ((strcmp(args[0].from, "verity")) == 0)
1798 entry->flags |= IMA_VERITY_REQUIRED;
1799 else
1800 result = -EINVAL;
1801 break;
1802 case Opt_appraise_type:
1803 ima_log_string(ab, "appraise_type", args[0].from);
1804
1805 if ((strcmp(args[0].from, "imasig")) == 0) {
1806 if (entry->flags & IMA_VERITY_REQUIRED)
1807 result = -EINVAL;
1808 else
1809 entry->flags |= IMA_DIGSIG_REQUIRED | IMA_CHECK_BLACKLIST;
1810 } else if (strcmp(args[0].from, "sigv3") == 0) {
1811 /* Only fsverity supports sigv3 for now */
1812 if (entry->flags & IMA_VERITY_REQUIRED)
1813 entry->flags |= IMA_DIGSIG_REQUIRED | IMA_CHECK_BLACKLIST;
1814 else
1815 result = -EINVAL;
1816 } else if (IS_ENABLED(CONFIG_IMA_APPRAISE_MODSIG) &&
1817 strcmp(args[0].from, "imasig|modsig") == 0) {
1818 if (entry->flags & IMA_VERITY_REQUIRED)
1819 result = -EINVAL;
1820 else
1821 entry->flags |= IMA_DIGSIG_REQUIRED |
1822 IMA_MODSIG_ALLOWED | IMA_CHECK_BLACKLIST;
1823 } else {
1824 result = -EINVAL;
1825 }
1826 break;
1827 case Opt_appraise_flag:
1828 ima_log_string(ab, "appraise_flag", args[0].from);
1829 break;
1830 case Opt_appraise_algos:
1831 ima_log_string(ab, "appraise_algos", args[0].from);
1832
1833 if (entry->allowed_algos) {
1834 result = -EINVAL;
1835 break;
1836 }
1837
1838 entry->allowed_algos =
1839 ima_parse_appraise_algos(args[0].from);
1840 /* invalid or empty list of algorithms */
1841 if (!entry->allowed_algos) {
1842 result = -EINVAL;
1843 break;
1844 }
1845
1846 entry->flags |= IMA_VALIDATE_ALGOS;
1847
1848 break;
1849 case Opt_permit_directio:
1850 entry->flags |= IMA_PERMIT_DIRECTIO;
1851 break;
1852 case Opt_pcr:
1853 ima_log_string(ab, "pcr", args[0].from);
1854
1855 result = kstrtoint(args[0].from, 10, &entry->pcr);
1856 if (result || INVALID_PCR(entry->pcr))
1857 result = -EINVAL;
1858 else
1859 entry->flags |= IMA_PCR;
1860
1861 break;
1862 case Opt_template:
1863 ima_log_string(ab, "template", args[0].from);
1864 if (entry->action != MEASURE) {
1865 result = -EINVAL;
1866 break;
1867 }
1868 template_desc = lookup_template_desc(args[0].from);
1869 if (!template_desc || entry->template) {
1870 result = -EINVAL;
1871 break;
1872 }
1873
1874 /*
1875 * template_desc_init_fields() does nothing if
1876 * the template is already initialised, so
1877 * it's safe to do this unconditionally
1878 */
1879 template_desc_init_fields(template_desc->fmt,
1880 &(template_desc->fields),
1881 &(template_desc->num_fields));
1882 entry->template = template_desc;
1883 break;
1884 case Opt_err:
1885 ima_log_string(ab, "UNKNOWN", p);
1886 result = -EINVAL;
1887 break;
1888 }
1889 }
1890 if (!result && !ima_validate_rule(entry))
1891 result = -EINVAL;
1892 else if (entry->action == APPRAISE)
1893 temp_ima_appraise |= ima_appraise_flag(entry->func);
1894
1895 if (!result && entry->flags & IMA_MODSIG_ALLOWED) {
1896 template_desc = entry->template ? entry->template :
1897 ima_template_desc_current();
1898 check_template_modsig(template_desc);
1899 }
1900
1901 /* d-ngv2 template field recommended for unsigned fs-verity digests */
1902 if (!result && entry->action == MEASURE &&
1903 entry->flags & IMA_VERITY_REQUIRED) {
1904 template_desc = entry->template ? entry->template :
1905 ima_template_desc_current();
1906 check_template_field(template_desc, "d-ngv2",
1907 "verity rules should include d-ngv2");
1908 }
1909
1910 audit_log_format(ab, "res=%d", !result);
1911 audit_log_end(ab);
1912 return result;
1913 }
1914
1915 /**
1916 * ima_parse_add_rule - add a rule to ima_policy_rules
1917 * @rule: ima measurement policy rule
1918 *
1919 * Avoid locking by allowing just one writer at a time in ima_write_policy()
1920 * Returns the length of the rule parsed, an error code on failure
1921 */
1922 ssize_t ima_parse_add_rule(char *rule)
1923 {
1924 static const char op[] = "update_policy";
1925 char *p;
1926 struct ima_rule_entry *entry;
1927 ssize_t result, len;
1928 int audit_info = 0;
1929
1930 p = strsep(&rule, "\n");
1931 len = strlen(p) + 1;
1932 p += strspn(p, " \t");
1933
1934 if (*p == '#' || *p == '\0')
1935 return len;
1936
1937 entry = kzalloc(sizeof(*entry), GFP_KERNEL);
1938 if (!entry) {
1939 integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
1940 NULL, op, "-ENOMEM", -ENOMEM, audit_info);
1941 return -ENOMEM;
1942 }
1943
1944 INIT_LIST_HEAD(&entry->list);
1945
1946 result = ima_parse_rule(p, entry);
1947 if (result) {
1948 ima_free_rule(entry);
1949 integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
1950 NULL, op, "invalid-policy", result,
1951 audit_info);
1952 return result;
1953 }
1954
1955 list_add_tail(&entry->list, &ima_temp_rules);
1956
1957 return len;
1958 }
1959
1960 /**
1961 * ima_delete_rules() - called to cleanup invalid in-flight policy.
1962 *
1963 * We don't need locking as we operate on the temp list, which is
1964 * different from the active one. There is also only one user of
1965 * ima_delete_rules() at a time.
1966 */
1967 void ima_delete_rules(void)
1968 {
1969 struct ima_rule_entry *entry, *tmp;
1970
1971 temp_ima_appraise = 0;
1972 list_for_each_entry_safe(entry, tmp, &ima_temp_rules, list) {
1973 list_del(&entry->list);
1974 ima_free_rule(entry);
1975 }
1976 }
1977
1978 #define __ima_hook_stringify(func, str) (#func),
1979
1980 const char *const func_tokens[] = {
1981 __ima_hooks(__ima_hook_stringify)
1982 };
1983
1984 #ifdef CONFIG_IMA_READ_POLICY
1985 enum {
1986 mask_exec = 0, mask_write, mask_read, mask_append
1987 };
1988
1989 static const char *const mask_tokens[] = {
1990 "^MAY_EXEC",
1991 "^MAY_WRITE",
1992 "^MAY_READ",
1993 "^MAY_APPEND"
1994 };
1995
1996 void *ima_policy_start(struct seq_file *m, loff_t *pos)
1997 {
1998 loff_t l = *pos;
1999 struct ima_rule_entry *entry;
2000 struct list_head *ima_rules_tmp;
2001
2002 rcu_read_lock();
2003 ima_rules_tmp = rcu_dereference(ima_rules);
2004 list_for_each_entry_rcu(entry, ima_rules_tmp, list) {
2005 if (!l--) {
2006 rcu_read_unlock();
2007 return entry;
2008 }
2009 }
2010 rcu_read_unlock();
2011 return NULL;
2012 }
2013
2014 void *ima_policy_next(struct seq_file *m, void *v, loff_t *pos)
2015 {
2016 struct ima_rule_entry *entry = v;
2017
2018 rcu_read_lock();
2019 entry = list_entry_rcu(entry->list.next, struct ima_rule_entry, list);
2020 rcu_read_unlock();
2021 (*pos)++;
2022
2023 return (&entry->list == &ima_default_rules ||
2024 &entry->list == &ima_policy_rules) ? NULL : entry;
2025 }
2026
2027 void ima_policy_stop(struct seq_file *m, void *v)
2028 {
2029 }
2030
2031 #define pt(token) policy_tokens[token].pattern
2032 #define mt(token) mask_tokens[token]
2033
2034 /*
2035 * policy_func_show - display the ima_hooks policy rule
2036 */
2037 static void policy_func_show(struct seq_file *m, enum ima_hooks func)
2038 {
2039 if (func > 0 && func < MAX_CHECK)
2040 seq_printf(m, "func=%s ", func_tokens[func]);
2041 else
2042 seq_printf(m, "func=%d ", func);
2043 }
2044
2045 static void ima_show_rule_opt_list(struct seq_file *m,
2046 const struct ima_rule_opt_list *opt_list)
2047 {
2048 size_t i;
2049
2050 for (i = 0; i < opt_list->count; i++)
2051 seq_printf(m, "%s%s", i ? "|" : "", opt_list->items[i]);
2052 }
2053
2054 static void ima_policy_show_appraise_algos(struct seq_file *m,
2055 unsigned int allowed_hashes)
2056 {
2057 int idx, list_size = 0;
2058
2059 for (idx = 0; idx < HASH_ALGO__LAST; idx++) {
2060 if (!(allowed_hashes & (1U << idx)))
2061 continue;
2062
2063 /* only add commas if the list contains multiple entries */
2064 if (list_size++)
2065 seq_puts(m, ",");
2066
2067 seq_puts(m, hash_algo_name[idx]);
2068 }
2069 }
2070
2071 int ima_policy_show(struct seq_file *m, void *v)
2072 {
2073 struct ima_rule_entry *entry = v;
2074 int i;
2075 char tbuf[64] = {0,};
2076 int offset = 0;
2077
2078 rcu_read_lock();
2079
2080 /* Do not print rules with inactive LSM labels */
2081 for (i = 0; i < MAX_LSM_RULES; i++) {
2082 if (entry->lsm[i].args_p && !entry->lsm[i].rule) {
2083 rcu_read_unlock();
2084 return 0;
2085 }
2086 }
2087
2088 if (entry->action & MEASURE)
2089 seq_puts(m, pt(Opt_measure));
2090 if (entry->action & DONT_MEASURE)
2091 seq_puts(m, pt(Opt_dont_measure));
2092 if (entry->action & APPRAISE)
2093 seq_puts(m, pt(Opt_appraise));
2094 if (entry->action & DONT_APPRAISE)
2095 seq_puts(m, pt(Opt_dont_appraise));
2096 if (entry->action & AUDIT)
2097 seq_puts(m, pt(Opt_audit));
2098 if (entry->action & HASH)
2099 seq_puts(m, pt(Opt_hash));
2100 if (entry->action & DONT_HASH)
2101 seq_puts(m, pt(Opt_dont_hash));
2102
2103 seq_puts(m, " ");
2104
2105 if (entry->flags & IMA_FUNC)
2106 policy_func_show(m, entry->func);
2107
2108 if ((entry->flags & IMA_MASK) || (entry->flags & IMA_INMASK)) {
2109 if (entry->flags & IMA_MASK)
2110 offset = 1;
2111 if (entry->mask & MAY_EXEC)
2112 seq_printf(m, pt(Opt_mask), mt(mask_exec) + offset);
2113 if (entry->mask & MAY_WRITE)
2114 seq_printf(m, pt(Opt_mask), mt(mask_write) + offset);
2115 if (entry->mask & MAY_READ)
2116 seq_printf(m, pt(Opt_mask), mt(mask_read) + offset);
2117 if (entry->mask & MAY_APPEND)
2118 seq_printf(m, pt(Opt_mask), mt(mask_append) + offset);
2119 seq_puts(m, " ");
2120 }
2121
2122 if (entry->flags & IMA_FSMAGIC) {
2123 snprintf(tbuf, sizeof(tbuf), "0x%lx", entry->fsmagic);
2124 seq_printf(m, pt(Opt_fsmagic), tbuf);
2125 seq_puts(m, " ");
2126 }
2127
2128 if (entry->flags & IMA_FSNAME) {
2129 snprintf(tbuf, sizeof(tbuf), "%s", entry->fsname);
2130 seq_printf(m, pt(Opt_fsname), tbuf);
2131 seq_puts(m, " ");
2132 }
2133
2134 if (entry->flags & IMA_KEYRINGS) {
2135 seq_puts(m, "keyrings=");
2136 ima_show_rule_opt_list(m, entry->keyrings);
2137 seq_puts(m, " ");
2138 }
2139
2140 if (entry->flags & IMA_LABEL) {
2141 seq_puts(m, "label=");
2142 ima_show_rule_opt_list(m, entry->label);
2143 seq_puts(m, " ");
2144 }
2145
2146 if (entry->flags & IMA_PCR) {
2147 snprintf(tbuf, sizeof(tbuf), "%d", entry->pcr);
2148 seq_printf(m, pt(Opt_pcr), tbuf);
2149 seq_puts(m, " ");
2150 }
2151
2152 if (entry->flags & IMA_FSUUID) {
2153 seq_printf(m, "fsuuid=%pU", &entry->fsuuid);
2154 seq_puts(m, " ");
2155 }
2156
2157 if (entry->flags & IMA_UID) {
2158 snprintf(tbuf, sizeof(tbuf), "%d", __kuid_val(entry->uid));
2159 if (entry->uid_op == &uid_gt)
2160 seq_printf(m, pt(Opt_uid_gt), tbuf);
2161 else if (entry->uid_op == &uid_lt)
2162 seq_printf(m, pt(Opt_uid_lt), tbuf);
2163 else
2164 seq_printf(m, pt(Opt_uid_eq), tbuf);
2165 seq_puts(m, " ");
2166 }
2167
2168 if (entry->flags & IMA_EUID) {
2169 snprintf(tbuf, sizeof(tbuf), "%d", __kuid_val(entry->uid));
2170 if (entry->uid_op == &uid_gt)
2171 seq_printf(m, pt(Opt_euid_gt), tbuf);
2172 else if (entry->uid_op == &uid_lt)
2173 seq_printf(m, pt(Opt_euid_lt), tbuf);
2174 else
2175 seq_printf(m, pt(Opt_euid_eq), tbuf);
2176 seq_puts(m, " ");
2177 }
2178
2179 if (entry->flags & IMA_GID) {
2180 snprintf(tbuf, sizeof(tbuf), "%d", __kgid_val(entry->gid));
2181 if (entry->gid_op == &gid_gt)
2182 seq_printf(m, pt(Opt_gid_gt), tbuf);
2183 else if (entry->gid_op == &gid_lt)
2184 seq_printf(m, pt(Opt_gid_lt), tbuf);
2185 else
2186 seq_printf(m, pt(Opt_gid_eq), tbuf);
2187 seq_puts(m, " ");
2188 }
2189
2190 if (entry->flags & IMA_EGID) {
2191 snprintf(tbuf, sizeof(tbuf), "%d", __kgid_val(entry->gid));
2192 if (entry->gid_op == &gid_gt)
2193 seq_printf(m, pt(Opt_egid_gt), tbuf);
2194 else if (entry->gid_op == &gid_lt)
2195 seq_printf(m, pt(Opt_egid_lt), tbuf);
2196 else
2197 seq_printf(m, pt(Opt_egid_eq), tbuf);
2198 seq_puts(m, " ");
2199 }
2200
2201 if (entry->flags & IMA_FOWNER) {
2202 snprintf(tbuf, sizeof(tbuf), "%d", __kuid_val(entry->fowner));
2203 if (entry->fowner_op == &vfsuid_gt_kuid)
2204 seq_printf(m, pt(Opt_fowner_gt), tbuf);
2205 else if (entry->fowner_op == &vfsuid_lt_kuid)
2206 seq_printf(m, pt(Opt_fowner_lt), tbuf);
2207 else
2208 seq_printf(m, pt(Opt_fowner_eq), tbuf);
2209 seq_puts(m, " ");
2210 }
2211
2212 if (entry->flags & IMA_FGROUP) {
2213 snprintf(tbuf, sizeof(tbuf), "%d", __kgid_val(entry->fgroup));
2214 if (entry->fgroup_op == &vfsgid_gt_kgid)
2215 seq_printf(m, pt(Opt_fgroup_gt), tbuf);
2216 else if (entry->fgroup_op == &vfsgid_lt_kgid)
2217 seq_printf(m, pt(Opt_fgroup_lt), tbuf);
2218 else
2219 seq_printf(m, pt(Opt_fgroup_eq), tbuf);
2220 seq_puts(m, " ");
2221 }
2222
2223 if (entry->flags & IMA_VALIDATE_ALGOS) {
2224 seq_puts(m, "appraise_algos=");
2225 ima_policy_show_appraise_algos(m, entry->allowed_algos);
2226 seq_puts(m, " ");
2227 }
2228
2229 for (i = 0; i < MAX_LSM_RULES; i++) {
2230 if (entry->lsm[i].rule) {
2231 switch (i) {
2232 case LSM_OBJ_USER:
2233 seq_printf(m, pt(Opt_obj_user),
2234 entry->lsm[i].args_p);
2235 break;
2236 case LSM_OBJ_ROLE:
2237 seq_printf(m, pt(Opt_obj_role),
2238 entry->lsm[i].args_p);
2239 break;
2240 case LSM_OBJ_TYPE:
2241 seq_printf(m, pt(Opt_obj_type),
2242 entry->lsm[i].args_p);
2243 break;
2244 case LSM_SUBJ_USER:
2245 seq_printf(m, pt(Opt_subj_user),
2246 entry->lsm[i].args_p);
2247 break;
2248 case LSM_SUBJ_ROLE:
2249 seq_printf(m, pt(Opt_subj_role),
2250 entry->lsm[i].args_p);
2251 break;
2252 case LSM_SUBJ_TYPE:
2253 seq_printf(m, pt(Opt_subj_type),
2254 entry->lsm[i].args_p);
2255 break;
2256 }
2257 seq_puts(m, " ");
2258 }
2259 }
2260 if (entry->template)
2261 seq_printf(m, "template=%s ", entry->template->name);
2262 if (entry->flags & IMA_DIGSIG_REQUIRED) {
2263 if (entry->flags & IMA_VERITY_REQUIRED)
2264 seq_puts(m, "appraise_type=sigv3 ");
2265 else if (entry->flags & IMA_MODSIG_ALLOWED)
2266 seq_puts(m, "appraise_type=imasig|modsig ");
2267 else
2268 seq_puts(m, "appraise_type=imasig ");
2269 }
2270 if (entry->flags & IMA_VERITY_REQUIRED)
2271 seq_puts(m, "digest_type=verity ");
2272 if (entry->flags & IMA_PERMIT_DIRECTIO)
2273 seq_puts(m, "permit_directio ");
2274 rcu_read_unlock();
2275 seq_puts(m, "\n");
2276 return 0;
2277 }
2278 #endif /* CONFIG_IMA_READ_POLICY */
2279
2280 #if defined(CONFIG_IMA_APPRAISE) && defined(CONFIG_INTEGRITY_TRUSTED_KEYRING)
2281 /*
2282 * ima_appraise_signature: whether IMA will appraise a given function using
2283 * an IMA digital signature. This is restricted to cases where the kernel
2284 * has a set of built-in trusted keys in order to avoid an attacker simply
2285 * loading additional keys.
2286 */
2287 bool ima_appraise_signature(enum kernel_read_file_id id)
2288 {
2289 struct ima_rule_entry *entry;
2290 bool found = false;
2291 enum ima_hooks func;
2292 struct list_head *ima_rules_tmp;
2293
2294 if (id >= READING_MAX_ID)
2295 return false;
2296
2297 if (id == READING_KEXEC_IMAGE && !(ima_appraise & IMA_APPRAISE_ENFORCE)
2298 && security_locked_down(LOCKDOWN_KEXEC))
2299 return false;
2300
2301 func = read_idmap[id] ?: FILE_CHECK;
2302
2303 rcu_read_lock();
2304 ima_rules_tmp = rcu_dereference(ima_rules);
2305 list_for_each_entry_rcu(entry, ima_rules_tmp, list) {
2306 if (entry->action != APPRAISE)
2307 continue;
2308
2309 /*
2310 * A generic entry will match, but otherwise require that it
2311 * match the func we're looking for
2312 */
2313 if (entry->func && entry->func != func)
2314 continue;
2315
2316 /*
2317 * We require this to be a digital signature, not a raw IMA
2318 * hash.
2319 */
2320 if (entry->flags & IMA_DIGSIG_REQUIRED)
2321 found = true;
2322
2323 /*
2324 * We've found a rule that matches, so break now even if it
2325 * didn't require a digital signature - a later rule that does
2326 * won't override it, so would be a false positive.
2327 */
2328 break;
2329 }
2330
2331 rcu_read_unlock();
2332 return found;
2333 }
2334 #endif /* CONFIG_IMA_APPRAISE && CONFIG_INTEGRITY_TRUSTED_KEYRING */
2335
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