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/kernel_read_file.h>
17#include <linux/slab.h>
18#include <linux/init.h>
19#include <linux/seq_file.h>
20#include <linux/rculist.h>
21#include <linux/rcupdate.h>
22#include <linux/parser.h>
23#include <linux/vmalloc.h>
24
25#include "ima.h"
26
27static DEFINE_MUTEX(ima_write_mutex);
28
29bool ima_canonical_fmt;
30static int __init default_canonical_fmt_setup(char *str)
31{
32#ifdef __BIG_ENDIAN
33	ima_canonical_fmt = true;
34#endif
35	return 1;
36}
37__setup("ima_canonical_fmt", default_canonical_fmt_setup);
38
39static int valid_policy = 1;
40
41static ssize_t ima_show_htable_value(char __user *buf, size_t count,
42				     loff_t *ppos, atomic_long_t *val)
43{
44	char tmpbuf[32];	/* greater than largest 'long' string value */
45	ssize_t len;
46
47	len = scnprintf(tmpbuf, sizeof(tmpbuf), "%li\n", atomic_long_read(val));
48	return simple_read_from_buffer(buf, count, ppos, tmpbuf, len);
49}
50
51static ssize_t ima_show_htable_violations(struct file *filp,
52					  char __user *buf,
53					  size_t count, loff_t *ppos)
54{
55	return ima_show_htable_value(buf, count, ppos, &ima_htable.violations);
56}
57
58static const struct file_operations ima_htable_violations_ops = {
59	.read = ima_show_htable_violations,
60	.llseek = generic_file_llseek,
61};
62
63static ssize_t ima_show_measurements_count(struct file *filp,
64					   char __user *buf,
65					   size_t count, loff_t *ppos)
66{
67	return ima_show_htable_value(buf, count, ppos, &ima_htable.len);
68
69}
70
71static const struct file_operations ima_measurements_count_ops = {
72	.read = ima_show_measurements_count,
73	.llseek = generic_file_llseek,
74};
75
76/* returns pointer to hlist_node */
77static void *ima_measurements_start(struct seq_file *m, loff_t *pos)
78{
79	loff_t l = *pos;
80	struct ima_queue_entry *qe;
81
82	/* we need a lock since pos could point beyond last element */
83	rcu_read_lock();
84	list_for_each_entry_rcu(qe, &ima_measurements, later) {
85		if (!l--) {
86			rcu_read_unlock();
87			return qe;
88		}
89	}
90	rcu_read_unlock();
91	return NULL;
92}
93
94static void *ima_measurements_next(struct seq_file *m, void *v, loff_t *pos)
95{
96	struct ima_queue_entry *qe = v;
97
98	/* lock protects when reading beyond last element
99	 * against concurrent list-extension
100	 */
101	rcu_read_lock();
102	qe = list_entry_rcu(qe->later.next, struct ima_queue_entry, later);
103	rcu_read_unlock();
104	(*pos)++;
105
106	return (&qe->later == &ima_measurements) ? NULL : qe;
107}
108
109static void ima_measurements_stop(struct seq_file *m, void *v)
110{
111}
112
113void ima_putc(struct seq_file *m, void *data, int datalen)
114{
115	while (datalen--)
116		seq_putc(m, *(char *)data++);
117}
118
119/* print format:
120 *       32bit-le=pcr#
121 *       char[20]=template digest
122 *       32bit-le=template name size
123 *       char[n]=template name
124 *       [eventdata length]
125 *       eventdata[n]=template specific data
126 */
127int ima_measurements_show(struct seq_file *m, void *v)
128{
129	/* the list never shrinks, so we don't need a lock here */
130	struct ima_queue_entry *qe = v;
131	struct ima_template_entry *e;
132	char *template_name;
133	u32 pcr, namelen, template_data_len; /* temporary fields */
134	bool is_ima_template = false;
135	int i;
136
137	/* get entry */
138	e = qe->entry;
139	if (e == NULL)
140		return -1;
141
142	template_name = (e->template_desc->name[0] != '\0') ?
143	    e->template_desc->name : e->template_desc->fmt;
144
145	/*
146	 * 1st: PCRIndex
147	 * PCR used defaults to the same (config option) in
148	 * little-endian format, unless set in policy
149	 */
150	pcr = !ima_canonical_fmt ? e->pcr : (__force u32)cpu_to_le32(e->pcr);
151	ima_putc(m, &pcr, sizeof(e->pcr));
152
153	/* 2nd: template digest */
154	ima_putc(m, e->digests[ima_sha1_idx].digest, TPM_DIGEST_SIZE);
155
156	/* 3rd: template name size */
157	namelen = !ima_canonical_fmt ? strlen(template_name) :
158		(__force u32)cpu_to_le32(strlen(template_name));
159	ima_putc(m, &namelen, sizeof(namelen));
160
161	/* 4th:  template name */
162	ima_putc(m, template_name, strlen(template_name));
163
164	/* 5th:  template length (except for 'ima' template) */
165	if (strcmp(template_name, IMA_TEMPLATE_IMA_NAME) == 0)
166		is_ima_template = true;
167
168	if (!is_ima_template) {
169		template_data_len = !ima_canonical_fmt ? e->template_data_len :
170			(__force u32)cpu_to_le32(e->template_data_len);
171		ima_putc(m, &template_data_len, sizeof(e->template_data_len));
172	}
173
174	/* 6th:  template specific data */
175	for (i = 0; i < e->template_desc->num_fields; i++) {
176		enum ima_show_type show = IMA_SHOW_BINARY;
177		const struct ima_template_field *field =
178			e->template_desc->fields[i];
179
180		if (is_ima_template && strcmp(field->field_id, "d") == 0)
181			show = IMA_SHOW_BINARY_NO_FIELD_LEN;
182		if (is_ima_template && strcmp(field->field_id, "n") == 0)
183			show = IMA_SHOW_BINARY_OLD_STRING_FMT;
184		field->field_show(m, show, &e->template_data[i]);
185	}
186	return 0;
187}
188
189static const struct seq_operations ima_measurments_seqops = {
190	.start = ima_measurements_start,
191	.next = ima_measurements_next,
192	.stop = ima_measurements_stop,
193	.show = ima_measurements_show
194};
195
196static int ima_measurements_open(struct inode *inode, struct file *file)
197{
198	return seq_open(file, &ima_measurments_seqops);
199}
200
201static const struct file_operations ima_measurements_ops = {
202	.open = ima_measurements_open,
203	.read = seq_read,
204	.llseek = seq_lseek,
205	.release = seq_release,
206};
207
208void ima_print_digest(struct seq_file *m, u8 *digest, u32 size)
209{
210	u32 i;
211
212	for (i = 0; i < size; i++)
213		seq_printf(m, "%02x", *(digest + i));
214}
215
216/* print in ascii */
217static int ima_ascii_measurements_show(struct seq_file *m, void *v)
218{
219	/* the list never shrinks, so we don't need a lock here */
220	struct ima_queue_entry *qe = v;
221	struct ima_template_entry *e;
222	char *template_name;
223	int i;
224
225	/* get entry */
226	e = qe->entry;
227	if (e == NULL)
228		return -1;
229
230	template_name = (e->template_desc->name[0] != '\0') ?
231	    e->template_desc->name : e->template_desc->fmt;
232
233	/* 1st: PCR used (config option) */
234	seq_printf(m, "%2d ", e->pcr);
235
236	/* 2nd: SHA1 template hash */
237	ima_print_digest(m, e->digests[ima_sha1_idx].digest, TPM_DIGEST_SIZE);
238
239	/* 3th:  template name */
240	seq_printf(m, " %s", template_name);
241
242	/* 4th:  template specific data */
243	for (i = 0; i < e->template_desc->num_fields; i++) {
244		seq_puts(m, " ");
245		if (e->template_data[i].len == 0)
246			continue;
247
248		e->template_desc->fields[i]->field_show(m, IMA_SHOW_ASCII,
249							&e->template_data[i]);
250	}
251	seq_puts(m, "\n");
252	return 0;
253}
254
255static const struct seq_operations ima_ascii_measurements_seqops = {
256	.start = ima_measurements_start,
257	.next = ima_measurements_next,
258	.stop = ima_measurements_stop,
259	.show = ima_ascii_measurements_show
260};
261
262static int ima_ascii_measurements_open(struct inode *inode, struct file *file)
263{
264	return seq_open(file, &ima_ascii_measurements_seqops);
265}
266
267static const struct file_operations ima_ascii_measurements_ops = {
268	.open = ima_ascii_measurements_open,
269	.read = seq_read,
270	.llseek = seq_lseek,
271	.release = seq_release,
272};
273
274static ssize_t ima_read_policy(char *path)
275{
276	void *data = NULL;
277	char *datap;
278	size_t size;
279	int rc, pathlen = strlen(path);
280
281	char *p;
282
283	/* remove \n */
284	datap = path;
285	strsep(&datap, "\n");
286
287	rc = kernel_read_file_from_path(path, 0, &data, INT_MAX, NULL,
288					READING_POLICY);
289	if (rc < 0) {
290		pr_err("Unable to open file: %s (%d)", path, rc);
291		return rc;
292	}
293	size = rc;
294	rc = 0;
295
296	datap = data;
297	while (size > 0 && (p = strsep(&datap, "\n"))) {
298		pr_debug("rule: %s\n", p);
299		rc = ima_parse_add_rule(p);
300		if (rc < 0)
301			break;
302		size -= rc;
303	}
304
305	vfree(data);
306	if (rc < 0)
307		return rc;
308	else if (size)
309		return -EINVAL;
310	else
311		return pathlen;
312}
313
314static ssize_t ima_write_policy(struct file *file, const char __user *buf,
315				size_t datalen, loff_t *ppos)
316{
317	char *data;
318	ssize_t result;
319
320	if (datalen >= PAGE_SIZE)
321		datalen = PAGE_SIZE - 1;
322
323	/* No partial writes. */
324	result = -EINVAL;
325	if (*ppos != 0)
326		goto out;
327
328	data = memdup_user_nul(buf, datalen);
329	if (IS_ERR(data)) {
330		result = PTR_ERR(data);
331		goto out;
332	}
333
334	result = mutex_lock_interruptible(&ima_write_mutex);
335	if (result < 0)
336		goto out_free;
337
338	if (data[0] == '/') {
339		result = ima_read_policy(data);
340	} else if (ima_appraise & IMA_APPRAISE_POLICY) {
341		pr_err("signed policy file (specified as an absolute pathname) required\n");
342		integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL, NULL,
343				    "policy_update", "signed policy required",
344				    1, 0);
345		result = -EACCES;
346	} else {
347		result = ima_parse_add_rule(data);
348	}
349	mutex_unlock(&ima_write_mutex);
350out_free:
351	kfree(data);
352out:
353	if (result < 0)
354		valid_policy = 0;
355
356	return result;
357}
358
359static struct dentry *ima_dir;
360static struct dentry *ima_symlink;
361static struct dentry *binary_runtime_measurements;
362static struct dentry *ascii_runtime_measurements;
363static struct dentry *runtime_measurements_count;
364static struct dentry *violations;
365static struct dentry *ima_policy;
366
367enum ima_fs_flags {
368	IMA_FS_BUSY,
369};
370
371static unsigned long ima_fs_flags;
372
373#ifdef	CONFIG_IMA_READ_POLICY
374static const struct seq_operations ima_policy_seqops = {
375		.start = ima_policy_start,
376		.next = ima_policy_next,
377		.stop = ima_policy_stop,
378		.show = ima_policy_show,
379};
380#endif
381
382/*
383 * ima_open_policy: sequentialize access to the policy file
384 */
385static int ima_open_policy(struct inode *inode, struct file *filp)
386{
387	if (!(filp->f_flags & O_WRONLY)) {
388#ifndef	CONFIG_IMA_READ_POLICY
389		return -EACCES;
390#else
391		if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
392			return -EACCES;
393		if (!capable(CAP_SYS_ADMIN))
394			return -EPERM;
395		return seq_open(filp, &ima_policy_seqops);
396#endif
397	}
398	if (test_and_set_bit(IMA_FS_BUSY, &ima_fs_flags))
399		return -EBUSY;
400	return 0;
401}
402
403/*
404 * ima_release_policy - start using the new measure policy rules.
405 *
406 * Initially, ima_measure points to the default policy rules, now
407 * point to the new policy rules, and remove the securityfs policy file,
408 * assuming a valid policy.
409 */
410static int ima_release_policy(struct inode *inode, struct file *file)
411{
412	const char *cause = valid_policy ? "completed" : "failed";
413
414	if ((file->f_flags & O_ACCMODE) == O_RDONLY)
415		return seq_release(inode, file);
416
417	if (valid_policy && ima_check_policy() < 0) {
418		cause = "failed";
419		valid_policy = 0;
420	}
421
422	pr_info("policy update %s\n", cause);
423	integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL, NULL,
424			    "policy_update", cause, !valid_policy, 0);
425
426	if (!valid_policy) {
427		ima_delete_rules();
428		valid_policy = 1;
429		clear_bit(IMA_FS_BUSY, &ima_fs_flags);
430		return 0;
431	}
432
433	ima_update_policy();
434#if !defined(CONFIG_IMA_WRITE_POLICY) && !defined(CONFIG_IMA_READ_POLICY)
435	securityfs_remove(ima_policy);
436	ima_policy = NULL;
437#elif defined(CONFIG_IMA_WRITE_POLICY)
438	clear_bit(IMA_FS_BUSY, &ima_fs_flags);
439#elif defined(CONFIG_IMA_READ_POLICY)
440	inode->i_mode &= ~S_IWUSR;
441#endif
442	return 0;
443}
444
445static const struct file_operations ima_measure_policy_ops = {
446	.open = ima_open_policy,
447	.write = ima_write_policy,
448	.read = seq_read,
449	.release = ima_release_policy,
450	.llseek = generic_file_llseek,
451};
452
453int __init ima_fs_init(void)
454{
455	int ret;
456
457	ima_dir = securityfs_create_dir("ima", integrity_dir);
458	if (IS_ERR(ima_dir))
459		return PTR_ERR(ima_dir);
460
461	ima_symlink = securityfs_create_symlink("ima", NULL, "integrity/ima",
462						NULL);
463	if (IS_ERR(ima_symlink)) {
464		ret = PTR_ERR(ima_symlink);
465		goto out;
466	}
467
468	binary_runtime_measurements =
469	    securityfs_create_file("binary_runtime_measurements",
470				   S_IRUSR | S_IRGRP, ima_dir, NULL,
471				   &ima_measurements_ops);
472	if (IS_ERR(binary_runtime_measurements)) {
473		ret = PTR_ERR(binary_runtime_measurements);
474		goto out;
475	}
476
477	ascii_runtime_measurements =
478	    securityfs_create_file("ascii_runtime_measurements",
479				   S_IRUSR | S_IRGRP, ima_dir, NULL,
480				   &ima_ascii_measurements_ops);
481	if (IS_ERR(ascii_runtime_measurements)) {
482		ret = PTR_ERR(ascii_runtime_measurements);
483		goto out;
484	}
485
486	runtime_measurements_count =
487	    securityfs_create_file("runtime_measurements_count",
488				   S_IRUSR | S_IRGRP, ima_dir, NULL,
489				   &ima_measurements_count_ops);
490	if (IS_ERR(runtime_measurements_count)) {
491		ret = PTR_ERR(runtime_measurements_count);
492		goto out;
493	}
494
495	violations =
496	    securityfs_create_file("violations", S_IRUSR | S_IRGRP,
497				   ima_dir, NULL, &ima_htable_violations_ops);
498	if (IS_ERR(violations)) {
499		ret = PTR_ERR(violations);
500		goto out;
501	}
502
503	ima_policy = securityfs_create_file("policy", POLICY_FILE_FLAGS,
504					    ima_dir, NULL,
505					    &ima_measure_policy_ops);
506	if (IS_ERR(ima_policy)) {
507		ret = PTR_ERR(ima_policy);
508		goto out;
509	}
510
511	return 0;
512out:
513	securityfs_remove(ima_policy);
514	securityfs_remove(violations);
515	securityfs_remove(runtime_measurements_count);
516	securityfs_remove(ascii_runtime_measurements);
517	securityfs_remove(binary_runtime_measurements);
518	securityfs_remove(ima_symlink);
519	securityfs_remove(ima_dir);
520
521	return ret;
522}
523