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[thirdparty/linux.git] / security / integrity / ima / ima_fs.c
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) 2005,2006,2007,2008 IBM Corporation
4 *
5 * Authors:
6 * Kylene Hall <kjhall@us.ibm.com>
7 * Reiner Sailer <sailer@us.ibm.com>
8 * Mimi Zohar <zohar@us.ibm.com>
9 *
10 * File: ima_fs.c
11 * implemenents security file system for reporting
12 * current measurement list and IMA statistics
13 */
14
15 #include <linux/fcntl.h>
16 #include <linux/slab.h>
17 #include <linux/init.h>
18 #include <linux/seq_file.h>
19 #include <linux/rculist.h>
20 #include <linux/rcupdate.h>
21 #include <linux/parser.h>
22 #include <linux/vmalloc.h>
23
24 #include "ima.h"
25
26 static DEFINE_MUTEX(ima_write_mutex);
27
28 bool ima_canonical_fmt;
29 static int __init default_canonical_fmt_setup(char *str)
30 {
31 #ifdef __BIG_ENDIAN
32 ima_canonical_fmt = true;
33 #endif
34 return 1;
35 }
36 __setup("ima_canonical_fmt", default_canonical_fmt_setup);
37
38 static int valid_policy = 1;
39
40 static ssize_t ima_show_htable_value(char __user *buf, size_t count,
41 loff_t *ppos, atomic_long_t *val)
42 {
43 char tmpbuf[32]; /* greater than largest 'long' string value */
44 ssize_t len;
45
46 len = scnprintf(tmpbuf, sizeof(tmpbuf), "%li\n", atomic_long_read(val));
47 return simple_read_from_buffer(buf, count, ppos, tmpbuf, len);
48 }
49
50 static ssize_t ima_show_htable_violations(struct file *filp,
51 char __user *buf,
52 size_t count, loff_t *ppos)
53 {
54 return ima_show_htable_value(buf, count, ppos, &ima_htable.violations);
55 }
56
57 static const struct file_operations ima_htable_violations_ops = {
58 .read = ima_show_htable_violations,
59 .llseek = generic_file_llseek,
60 };
61
62 static ssize_t ima_show_measurements_count(struct file *filp,
63 char __user *buf,
64 size_t count, loff_t *ppos)
65 {
66 return ima_show_htable_value(buf, count, ppos, &ima_htable.len);
67
68 }
69
70 static const struct file_operations ima_measurements_count_ops = {
71 .read = ima_show_measurements_count,
72 .llseek = generic_file_llseek,
73 };
74
75 /* returns pointer to hlist_node */
76 static void *ima_measurements_start(struct seq_file *m, loff_t *pos)
77 {
78 loff_t l = *pos;
79 struct ima_queue_entry *qe;
80
81 /* we need a lock since pos could point beyond last element */
82 rcu_read_lock();
83 list_for_each_entry_rcu(qe, &ima_measurements, later) {
84 if (!l--) {
85 rcu_read_unlock();
86 return qe;
87 }
88 }
89 rcu_read_unlock();
90 return NULL;
91 }
92
93 static void *ima_measurements_next(struct seq_file *m, void *v, loff_t *pos)
94 {
95 struct ima_queue_entry *qe = v;
96
97 /* lock protects when reading beyond last element
98 * against concurrent list-extension
99 */
100 rcu_read_lock();
101 qe = list_entry_rcu(qe->later.next, struct ima_queue_entry, later);
102 rcu_read_unlock();
103 (*pos)++;
104
105 return (&qe->later == &ima_measurements) ? NULL : qe;
106 }
107
108 static void ima_measurements_stop(struct seq_file *m, void *v)
109 {
110 }
111
112 void ima_putc(struct seq_file *m, void *data, int datalen)
113 {
114 while (datalen--)
115 seq_putc(m, *(char *)data++);
116 }
117
118 /* print format:
119 * 32bit-le=pcr#
120 * char[20]=template digest
121 * 32bit-le=template name size
122 * char[n]=template name
123 * [eventdata length]
124 * eventdata[n]=template specific data
125 */
126 int ima_measurements_show(struct seq_file *m, void *v)
127 {
128 /* the list never shrinks, so we don't need a lock here */
129 struct ima_queue_entry *qe = v;
130 struct ima_template_entry *e;
131 char *template_name;
132 u32 pcr, namelen, template_data_len; /* temporary fields */
133 bool is_ima_template = false;
134 int i;
135
136 /* get entry */
137 e = qe->entry;
138 if (e == NULL)
139 return -1;
140
141 template_name = (e->template_desc->name[0] != '\0') ?
142 e->template_desc->name : e->template_desc->fmt;
143
144 /*
145 * 1st: PCRIndex
146 * PCR used defaults to the same (config option) in
147 * little-endian format, unless set in policy
148 */
149 pcr = !ima_canonical_fmt ? e->pcr : cpu_to_le32(e->pcr);
150 ima_putc(m, &pcr, sizeof(e->pcr));
151
152 /* 2nd: template digest */
153 ima_putc(m, e->digest, TPM_DIGEST_SIZE);
154
155 /* 3rd: template name size */
156 namelen = !ima_canonical_fmt ? strlen(template_name) :
157 cpu_to_le32(strlen(template_name));
158 ima_putc(m, &namelen, sizeof(namelen));
159
160 /* 4th: template name */
161 ima_putc(m, template_name, strlen(template_name));
162
163 /* 5th: template length (except for 'ima' template) */
164 if (strcmp(template_name, IMA_TEMPLATE_IMA_NAME) == 0)
165 is_ima_template = true;
166
167 if (!is_ima_template) {
168 template_data_len = !ima_canonical_fmt ? e->template_data_len :
169 cpu_to_le32(e->template_data_len);
170 ima_putc(m, &template_data_len, sizeof(e->template_data_len));
171 }
172
173 /* 6th: template specific data */
174 for (i = 0; i < e->template_desc->num_fields; i++) {
175 enum ima_show_type show = IMA_SHOW_BINARY;
176 const struct ima_template_field *field =
177 e->template_desc->fields[i];
178
179 if (is_ima_template && strcmp(field->field_id, "d") == 0)
180 show = IMA_SHOW_BINARY_NO_FIELD_LEN;
181 if (is_ima_template && strcmp(field->field_id, "n") == 0)
182 show = IMA_SHOW_BINARY_OLD_STRING_FMT;
183 field->field_show(m, show, &e->template_data[i]);
184 }
185 return 0;
186 }
187
188 static const struct seq_operations ima_measurments_seqops = {
189 .start = ima_measurements_start,
190 .next = ima_measurements_next,
191 .stop = ima_measurements_stop,
192 .show = ima_measurements_show
193 };
194
195 static int ima_measurements_open(struct inode *inode, struct file *file)
196 {
197 return seq_open(file, &ima_measurments_seqops);
198 }
199
200 static const struct file_operations ima_measurements_ops = {
201 .open = ima_measurements_open,
202 .read = seq_read,
203 .llseek = seq_lseek,
204 .release = seq_release,
205 };
206
207 void ima_print_digest(struct seq_file *m, u8 *digest, u32 size)
208 {
209 u32 i;
210
211 for (i = 0; i < size; i++)
212 seq_printf(m, "%02x", *(digest + i));
213 }
214
215 /* print in ascii */
216 static int ima_ascii_measurements_show(struct seq_file *m, void *v)
217 {
218 /* the list never shrinks, so we don't need a lock here */
219 struct ima_queue_entry *qe = v;
220 struct ima_template_entry *e;
221 char *template_name;
222 int i;
223
224 /* get entry */
225 e = qe->entry;
226 if (e == NULL)
227 return -1;
228
229 template_name = (e->template_desc->name[0] != '\0') ?
230 e->template_desc->name : e->template_desc->fmt;
231
232 /* 1st: PCR used (config option) */
233 seq_printf(m, "%2d ", e->pcr);
234
235 /* 2nd: SHA1 template hash */
236 ima_print_digest(m, e->digest, TPM_DIGEST_SIZE);
237
238 /* 3th: template name */
239 seq_printf(m, " %s", template_name);
240
241 /* 4th: template specific data */
242 for (i = 0; i < e->template_desc->num_fields; i++) {
243 seq_puts(m, " ");
244 if (e->template_data[i].len == 0)
245 continue;
246
247 e->template_desc->fields[i]->field_show(m, IMA_SHOW_ASCII,
248 &e->template_data[i]);
249 }
250 seq_puts(m, "\n");
251 return 0;
252 }
253
254 static const struct seq_operations ima_ascii_measurements_seqops = {
255 .start = ima_measurements_start,
256 .next = ima_measurements_next,
257 .stop = ima_measurements_stop,
258 .show = ima_ascii_measurements_show
259 };
260
261 static int ima_ascii_measurements_open(struct inode *inode, struct file *file)
262 {
263 return seq_open(file, &ima_ascii_measurements_seqops);
264 }
265
266 static const struct file_operations ima_ascii_measurements_ops = {
267 .open = ima_ascii_measurements_open,
268 .read = seq_read,
269 .llseek = seq_lseek,
270 .release = seq_release,
271 };
272
273 static ssize_t ima_read_policy(char *path)
274 {
275 void *data;
276 char *datap;
277 loff_t size;
278 int rc, pathlen = strlen(path);
279
280 char *p;
281
282 /* remove \n */
283 datap = path;
284 strsep(&datap, "\n");
285
286 rc = kernel_read_file_from_path(path, &data, &size, 0, READING_POLICY);
287 if (rc < 0) {
288 pr_err("Unable to open file: %s (%d)", path, rc);
289 return rc;
290 }
291
292 datap = data;
293 while (size > 0 && (p = strsep(&datap, "\n"))) {
294 pr_debug("rule: %s\n", p);
295 rc = ima_parse_add_rule(p);
296 if (rc < 0)
297 break;
298 size -= rc;
299 }
300
301 vfree(data);
302 if (rc < 0)
303 return rc;
304 else if (size)
305 return -EINVAL;
306 else
307 return pathlen;
308 }
309
310 static ssize_t ima_write_policy(struct file *file, const char __user *buf,
311 size_t datalen, loff_t *ppos)
312 {
313 char *data;
314 ssize_t result;
315
316 if (datalen >= PAGE_SIZE)
317 datalen = PAGE_SIZE - 1;
318
319 /* No partial writes. */
320 result = -EINVAL;
321 if (*ppos != 0)
322 goto out;
323
324 data = memdup_user_nul(buf, datalen);
325 if (IS_ERR(data)) {
326 result = PTR_ERR(data);
327 goto out;
328 }
329
330 result = mutex_lock_interruptible(&ima_write_mutex);
331 if (result < 0)
332 goto out_free;
333
334 if (data[0] == '/') {
335 result = ima_read_policy(data);
336 } else if (ima_appraise & IMA_APPRAISE_POLICY) {
337 pr_err("signed policy file (specified as an absolute pathname) required\n");
338 integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL, NULL,
339 "policy_update", "signed policy required",
340 1, 0);
341 result = -EACCES;
342 } else {
343 result = ima_parse_add_rule(data);
344 }
345 mutex_unlock(&ima_write_mutex);
346 out_free:
347 kfree(data);
348 out:
349 if (result < 0)
350 valid_policy = 0;
351
352 return result;
353 }
354
355 static struct dentry *ima_dir;
356 static struct dentry *ima_symlink;
357 static struct dentry *binary_runtime_measurements;
358 static struct dentry *ascii_runtime_measurements;
359 static struct dentry *runtime_measurements_count;
360 static struct dentry *violations;
361 static struct dentry *ima_policy;
362
363 enum ima_fs_flags {
364 IMA_FS_BUSY,
365 };
366
367 static unsigned long ima_fs_flags;
368
369 #ifdef CONFIG_IMA_READ_POLICY
370 static const struct seq_operations ima_policy_seqops = {
371 .start = ima_policy_start,
372 .next = ima_policy_next,
373 .stop = ima_policy_stop,
374 .show = ima_policy_show,
375 };
376 #endif
377
378 /*
379 * ima_open_policy: sequentialize access to the policy file
380 */
381 static int ima_open_policy(struct inode *inode, struct file *filp)
382 {
383 if (!(filp->f_flags & O_WRONLY)) {
384 #ifndef CONFIG_IMA_READ_POLICY
385 return -EACCES;
386 #else
387 if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
388 return -EACCES;
389 if (!capable(CAP_SYS_ADMIN))
390 return -EPERM;
391 return seq_open(filp, &ima_policy_seqops);
392 #endif
393 }
394 if (test_and_set_bit(IMA_FS_BUSY, &ima_fs_flags))
395 return -EBUSY;
396 return 0;
397 }
398
399 /*
400 * ima_release_policy - start using the new measure policy rules.
401 *
402 * Initially, ima_measure points to the default policy rules, now
403 * point to the new policy rules, and remove the securityfs policy file,
404 * assuming a valid policy.
405 */
406 static int ima_release_policy(struct inode *inode, struct file *file)
407 {
408 const char *cause = valid_policy ? "completed" : "failed";
409
410 if ((file->f_flags & O_ACCMODE) == O_RDONLY)
411 return seq_release(inode, file);
412
413 if (valid_policy && ima_check_policy() < 0) {
414 cause = "failed";
415 valid_policy = 0;
416 }
417
418 pr_info("policy update %s\n", cause);
419 integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL, NULL,
420 "policy_update", cause, !valid_policy, 0);
421
422 if (!valid_policy) {
423 ima_delete_rules();
424 valid_policy = 1;
425 clear_bit(IMA_FS_BUSY, &ima_fs_flags);
426 return 0;
427 }
428
429 ima_update_policy();
430 #if !defined(CONFIG_IMA_WRITE_POLICY) && !defined(CONFIG_IMA_READ_POLICY)
431 securityfs_remove(ima_policy);
432 ima_policy = NULL;
433 #elif defined(CONFIG_IMA_WRITE_POLICY)
434 clear_bit(IMA_FS_BUSY, &ima_fs_flags);
435 #elif defined(CONFIG_IMA_READ_POLICY)
436 inode->i_mode &= ~S_IWUSR;
437 #endif
438 return 0;
439 }
440
441 static const struct file_operations ima_measure_policy_ops = {
442 .open = ima_open_policy,
443 .write = ima_write_policy,
444 .read = seq_read,
445 .release = ima_release_policy,
446 .llseek = generic_file_llseek,
447 };
448
449 int __init ima_fs_init(void)
450 {
451 ima_dir = securityfs_create_dir("ima", integrity_dir);
452 if (IS_ERR(ima_dir))
453 return -1;
454
455 ima_symlink = securityfs_create_symlink("ima", NULL, "integrity/ima",
456 NULL);
457 if (IS_ERR(ima_symlink))
458 goto out;
459
460 binary_runtime_measurements =
461 securityfs_create_file("binary_runtime_measurements",
462 S_IRUSR | S_IRGRP, ima_dir, NULL,
463 &ima_measurements_ops);
464 if (IS_ERR(binary_runtime_measurements))
465 goto out;
466
467 ascii_runtime_measurements =
468 securityfs_create_file("ascii_runtime_measurements",
469 S_IRUSR | S_IRGRP, ima_dir, NULL,
470 &ima_ascii_measurements_ops);
471 if (IS_ERR(ascii_runtime_measurements))
472 goto out;
473
474 runtime_measurements_count =
475 securityfs_create_file("runtime_measurements_count",
476 S_IRUSR | S_IRGRP, ima_dir, NULL,
477 &ima_measurements_count_ops);
478 if (IS_ERR(runtime_measurements_count))
479 goto out;
480
481 violations =
482 securityfs_create_file("violations", S_IRUSR | S_IRGRP,
483 ima_dir, NULL, &ima_htable_violations_ops);
484 if (IS_ERR(violations))
485 goto out;
486
487 ima_policy = securityfs_create_file("policy", POLICY_FILE_FLAGS,
488 ima_dir, NULL,
489 &ima_measure_policy_ops);
490 if (IS_ERR(ima_policy))
491 goto out;
492
493 return 0;
494 out:
495 securityfs_remove(violations);
496 securityfs_remove(runtime_measurements_count);
497 securityfs_remove(ascii_runtime_measurements);
498 securityfs_remove(binary_runtime_measurements);
499 securityfs_remove(ima_symlink);
500 securityfs_remove(ima_dir);
501 securityfs_remove(ima_policy);
502 return -1;
503 }