summaryrefslogtreecommitdiff
path: root/security/integrity/ima/ima_fs.c
blob: a3cf5c0ab501c18d27c5f152cdfe0ae5a1ad4394 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
/*
 * Copyright (C) 2005,2006,2007,2008 IBM Corporation
 *
 * Authors:
 * Kylene Hall <kjhall@us.ibm.com>
 * Reiner Sailer <sailer@us.ibm.com>
 * Mimi Zohar <zohar@us.ibm.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation, version 2 of the
 * License.
 *
 * File: ima_fs.c
 *	implemenents security file system for reporting
 *	current measurement list and IMA statistics
 */
#include <linux/fcntl.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/seq_file.h>
#include <linux/rculist.h>
#include <linux/rcupdate.h>
#include <linux/parser.h>

#include "ima.h"

static DEFINE_MUTEX(ima_write_mutex);

static int valid_policy = 1;
#define TMPBUFLEN 12
static ssize_t ima_show_htable_value(char __user *buf, size_t count,
				     loff_t *ppos, atomic_long_t *val)
{
	char tmpbuf[TMPBUFLEN];
	ssize_t len;

	len = scnprintf(tmpbuf, TMPBUFLEN, "%li\n", atomic_long_read(val));
	return simple_read_from_buffer(buf, count, ppos, tmpbuf, len);
}

static ssize_t ima_show_htable_violations(struct file *filp,
					  char __user *buf,
					  size_t count, loff_t *ppos)
{
	return ima_show_htable_value(buf, count, ppos, &ima_htable.violations);
}

static const struct file_operations ima_htable_violations_ops = {
	.read = ima_show_htable_violations,
	.llseek = generic_file_llseek,
};

static ssize_t ima_show_measurements_count(struct file *filp,
					   char __user *buf,
					   size_t count, loff_t *ppos)
{
	return ima_show_htable_value(buf, count, ppos, &ima_htable.len);

}

static const struct file_operations ima_measurements_count_ops = {
	.read = ima_show_measurements_count,
	.llseek = generic_file_llseek,
};

/* returns pointer to hlist_node */
static void *ima_measurements_start(struct seq_file *m, loff_t *pos)
{
	loff_t l = *pos;
	struct ima_queue_entry *qe;

	/* we need a lock since pos could point beyond last element */
	rcu_read_lock();
	list_for_each_entry_rcu(qe, &ima_measurements, later) {
		if (!l--) {
			rcu_read_unlock();
			return qe;
		}
	}
	rcu_read_unlock();
	return NULL;
}

static void *ima_measurements_next(struct seq_file *m, void *v, loff_t *pos)
{
	struct ima_queue_entry *qe = v;

	/* lock protects when reading beyond last element
	 * against concurrent list-extension
	 */
	rcu_read_lock();
	qe = list_entry_rcu(qe->later.next, struct ima_queue_entry, later);
	rcu_read_unlock();
	(*pos)++;

	return (&qe->later == &ima_measurements) ? NULL : qe;
}

static void ima_measurements_stop(struct seq_file *m, void *v)
{
}

void ima_putc(struct seq_file *m, void *data, int datalen)
{
	while (datalen--)
		seq_putc(m, *(char *)data++);
}

/* print format:
 *       32bit-le=pcr#
 *       char[20]=template digest
 *       32bit-le=template name size
 *       char[n]=template name
 *       [eventdata length]
 *       eventdata[n]=template specific data
 */
static int ima_measurements_show(struct seq_file *m, void *v)
{
	/* the list never shrinks, so we don't need a lock here */
	struct ima_queue_entry *qe = v;
	struct ima_template_entry *e;
	char *template_name;
	int namelen;
	u32 pcr = CONFIG_IMA_MEASURE_PCR_IDX;
	bool is_ima_template = false;
	int i;

	/* get entry */
	e = qe->entry;
	if (e == NULL)
		return -1;

	template_name = (e->template_desc->name[0] != '\0') ?
	    e->template_desc->name : e->template_desc->fmt;

	/*
	 * 1st: PCRIndex
	 * PCR used is always the same (config option) in
	 * little-endian format
	 */
	ima_putc(m, &pcr, sizeof(pcr));

	/* 2nd: template digest */
	ima_putc(m, e->digest, TPM_DIGEST_SIZE);

	/* 3rd: template name size */
	namelen = strlen(template_name);
	ima_putc(m, &namelen, sizeof(namelen));

	/* 4th:  template name */
	ima_putc(m, template_name, namelen);

	/* 5th:  template length (except for 'ima' template) */
	if (strcmp(template_name, IMA_TEMPLATE_IMA_NAME) == 0)
		is_ima_template = true;

	if (!is_ima_template)
		ima_putc(m, &e->template_data_len,
			 sizeof(e->template_data_len));

	/* 6th:  template specific data */
	for (i = 0; i < e->template_desc->num_fields; i++) {
		enum ima_show_type show = IMA_SHOW_BINARY;
		struct ima_template_field *field = e->template_desc->fields[i];

		if (is_ima_template && strcmp(field->field_id, "d") == 0)
			show = IMA_SHOW_BINARY_NO_FIELD_LEN;
		if (is_ima_template && strcmp(field->field_id, "n") == 0)
			show = IMA_SHOW_BINARY_OLD_STRING_FMT;
		field->field_show(m, show, &e->template_data[i]);
	}
	return 0;
}

static const struct seq_operations ima_measurments_seqops = {
	.start = ima_measurements_start,
	.next = ima_measurements_next,
	.stop = ima_measurements_stop,
	.show = ima_measurements_show
};

static int ima_measurements_open(struct inode *inode, struct file *file)
{
	return seq_open(file, &ima_measurments_seqops);
}

static const struct file_operations ima_measurements_ops = {
	.open = ima_measurements_open,
	.read = seq_read,
	.llseek = seq_lseek,
	.release = seq_release,
};

void ima_print_digest(struct seq_file *m, u8 *digest, u32 size)
{
	u32 i;

	for (i = 0; i < size; i++)
		seq_printf(m, "%02x", *(digest + i));
}

/* print in ascii */
static int ima_ascii_measurements_show(struct seq_file *m, void *v)
{
	/* the list never shrinks, so we don't need a lock here */
	struct ima_queue_entry *qe = v;
	struct ima_template_entry *e;
	char *template_name;
	int i;

	/* get entry */
	e = qe->entry;
	if (e == NULL)
		return -1;

	template_name = (e->template_desc->name[0] != '\0') ?
	    e->template_desc->name : e->template_desc->fmt;

	/* 1st: PCR used (config option) */
	seq_printf(m, "%2d ", CONFIG_IMA_MEASURE_PCR_IDX);

	/* 2nd: SHA1 template hash */
	ima_print_digest(m, e->digest, TPM_DIGEST_SIZE);

	/* 3th:  template name */
	seq_printf(m, " %s", template_name);

	/* 4th:  template specific data */
	for (i = 0; i < e->template_desc->num_fields; i++) {
		seq_puts(m, " ");
		if (e->template_data[i].len == 0)
			continue;

		e->template_desc->fields[i]->field_show(m, IMA_SHOW_ASCII,
							&e->template_data[i]);
	}
	seq_puts(m, "\n");
	return 0;
}

static const struct seq_operations ima_ascii_measurements_seqops = {
	.start = ima_measurements_start,
	.next = ima_measurements_next,
	.stop = ima_measurements_stop,
	.show = ima_ascii_measurements_show
};

static int ima_ascii_measurements_open(struct inode *inode, struct file *file)
{
	return seq_open(file, &ima_ascii_measurements_seqops);
}

static const struct file_operations ima_ascii_measurements_ops = {
	.open = ima_ascii_measurements_open,
	.read = seq_read,
	.llseek = seq_lseek,
	.release = seq_release,
};

static ssize_t ima_write_policy(struct file *file, const char __user *buf,
				size_t datalen, loff_t *ppos)
{
	char *data = NULL;
	ssize_t result;
	int res;

	res = mutex_lock_interruptible(&ima_write_mutex);
	if (res)
		return res;

	if (datalen >= PAGE_SIZE)
		datalen = PAGE_SIZE - 1;

	/* No partial writes. */
	result = -EINVAL;
	if (*ppos != 0)
		goto out;

	result = -ENOMEM;
	data = kmalloc(datalen + 1, GFP_KERNEL);
	if (!data)
		goto out;

	*(data + datalen) = '\0';

	result = -EFAULT;
	if (copy_from_user(data, buf, datalen))
		goto out;

	result = ima_parse_add_rule(data);
out:
	if (result < 0)
		valid_policy = 0;
	kfree(data);
	mutex_unlock(&ima_write_mutex);

	return result;
}

static struct dentry *ima_dir;
static struct dentry *binary_runtime_measurements;
static struct dentry *ascii_runtime_measurements;
static struct dentry *runtime_measurements_count;
static struct dentry *violations;
static struct dentry *ima_policy;

enum ima_fs_flags {
	IMA_FS_BUSY,
};

static unsigned long ima_fs_flags;

/*
 * ima_open_policy: sequentialize access to the policy file
 */
static int ima_open_policy(struct inode *inode, struct file *filp)
{
	/* No point in being allowed to open it if you aren't going to write */
	if (!(filp->f_flags & O_WRONLY))
		return -EACCES;
	if (test_and_set_bit(IMA_FS_BUSY, &ima_fs_flags))
		return -EBUSY;
	return 0;
}

/*
 * ima_release_policy - start using the new measure policy rules.
 *
 * Initially, ima_measure points to the default policy rules, now
 * point to the new policy rules, and remove the securityfs policy file,
 * assuming a valid policy.
 */
static int ima_release_policy(struct inode *inode, struct file *file)
{
	const char *cause = valid_policy ? "completed" : "failed";

	pr_info("IMA: policy update %s\n", cause);
	integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL, NULL,
			    "policy_update", cause, !valid_policy, 0);

	if (!valid_policy) {
		ima_delete_rules();
		valid_policy = 1;
		clear_bit(IMA_FS_BUSY, &ima_fs_flags);
		return 0;
	}
	ima_update_policy();
#ifndef	CONFIG_IMA_WRITE_POLICY
	securityfs_remove(ima_policy);
	ima_policy = NULL;
#else
	clear_bit(IMA_FS_BUSY, &ima_fs_flags);
#endif
	return 0;
}

static const struct file_operations ima_measure_policy_ops = {
	.open = ima_open_policy,
	.write = ima_write_policy,
	.release = ima_release_policy,
	.llseek = generic_file_llseek,
};

int __init ima_fs_init(void)
{
	ima_dir = securityfs_create_dir("ima", NULL);
	if (IS_ERR(ima_dir))
		return -1;

	binary_runtime_measurements =
	    securityfs_create_file("binary_runtime_measurements",
				   S_IRUSR | S_IRGRP, ima_dir, NULL,
				   &ima_measurements_ops);
	if (IS_ERR(binary_runtime_measurements))
		goto out;

	ascii_runtime_measurements =
	    securityfs_create_file("ascii_runtime_measurements",
				   S_IRUSR | S_IRGRP, ima_dir, NULL,
				   &ima_ascii_measurements_ops);
	if (IS_ERR(ascii_runtime_measurements))
		goto out;

	runtime_measurements_count =
	    securityfs_create_file("runtime_measurements_count",
				   S_IRUSR | S_IRGRP, ima_dir, NULL,
				   &ima_measurements_count_ops);
	if (IS_ERR(runtime_measurements_count))
		goto out;

	violations =
	    securityfs_create_file("violations", S_IRUSR | S_IRGRP,
				   ima_dir, NULL, &ima_htable_violations_ops);
	if (IS_ERR(violations))
		goto out;

	ima_policy = securityfs_create_file("policy",
					    S_IWUSR,
					    ima_dir, NULL,
					    &ima_measure_policy_ops);
	if (IS_ERR(ima_policy))
		goto out;

	return 0;
out:
	securityfs_remove(violations);
	securityfs_remove(runtime_measurements_count);
	securityfs_remove(ascii_runtime_measurements);
	securityfs_remove(binary_runtime_measurements);
	securityfs_remove(ima_dir);
	securityfs_remove(ima_policy);
	return -1;
}