1/*
2 * Copyright (C) 2005,2006,2007,2008 IBM Corporation
3 *
4 * Authors:
5 * Kylene Hall <kjhall@us.ibm.com>
6 * Reiner Sailer <sailer@us.ibm.com>
7 * Mimi Zohar <zohar@us.ibm.com>
8 *
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License as
11 * published by the Free Software Foundation, version 2 of the
12 * License.
13 *
14 * File: ima_fs.c
15 *	implemenents security file system for reporting
16 *	current measurement list and IMA statistics
17 */
18#include <linux/fcntl.h>
19#include <linux/slab.h>
20#include <linux/module.h>
21#include <linux/seq_file.h>
22#include <linux/rculist.h>
23#include <linux/rcupdate.h>
24#include <linux/parser.h>
25
26#include "ima.h"
27
28static int valid_policy = 1;
29#define TMPBUFLEN 12
30static ssize_t ima_show_htable_value(char __user *buf, size_t count,
31				     loff_t *ppos, atomic_long_t *val)
32{
33	char tmpbuf[TMPBUFLEN];
34	ssize_t len;
35
36	len = scnprintf(tmpbuf, TMPBUFLEN, "%li\n", atomic_long_read(val));
37	return simple_read_from_buffer(buf, count, ppos, tmpbuf, len);
38}
39
40static ssize_t ima_show_htable_violations(struct file *filp,
41					  char __user *buf,
42					  size_t count, loff_t *ppos)
43{
44	return ima_show_htable_value(buf, count, ppos, &ima_htable.violations);
45}
46
47static const struct file_operations ima_htable_violations_ops = {
48	.read = ima_show_htable_violations,
49	.llseek = generic_file_llseek,
50};
51
52static ssize_t ima_show_measurements_count(struct file *filp,
53					   char __user *buf,
54					   size_t count, loff_t *ppos)
55{
56	return ima_show_htable_value(buf, count, ppos, &ima_htable.len);
57
58}
59
60static const struct file_operations ima_measurements_count_ops = {
61	.read = ima_show_measurements_count,
62	.llseek = generic_file_llseek,
63};
64
65/* returns pointer to hlist_node */
66static void *ima_measurements_start(struct seq_file *m, loff_t *pos)
67{
68	loff_t l = *pos;
69	struct ima_queue_entry *qe;
70
71	/* we need a lock since pos could point beyond last element */
72	rcu_read_lock();
73	list_for_each_entry_rcu(qe, &ima_measurements, later) {
74		if (!l--) {
75			rcu_read_unlock();
76			return qe;
77		}
78	}
79	rcu_read_unlock();
80	return NULL;
81}
82
83static void *ima_measurements_next(struct seq_file *m, void *v, loff_t *pos)
84{
85	struct ima_queue_entry *qe = v;
86
87	/* lock protects when reading beyond last element
88	 * against concurrent list-extension
89	 */
90	rcu_read_lock();
91	qe = list_entry_rcu(qe->later.next, struct ima_queue_entry, later);
92	rcu_read_unlock();
93	(*pos)++;
94
95	return (&qe->later == &ima_measurements) ? NULL : qe;
96}
97
98static void ima_measurements_stop(struct seq_file *m, void *v)
99{
100}
101
102void ima_putc(struct seq_file *m, void *data, int datalen)
103{
104	while (datalen--)
105		seq_putc(m, *(char *)data++);
106}
107
108/* print format:
109 *       32bit-le=pcr#
110 *       char[20]=template digest
111 *       32bit-le=template name size
112 *       char[n]=template name
113 *       [eventdata length]
114 *       eventdata[n]=template specific data
115 */
116static int ima_measurements_show(struct seq_file *m, void *v)
117{
118	/* the list never shrinks, so we don't need a lock here */
119	struct ima_queue_entry *qe = v;
120	struct ima_template_entry *e;
121	char *template_name;
122	int namelen;
123	u32 pcr = CONFIG_IMA_MEASURE_PCR_IDX;
124	bool is_ima_template = false;
125	int i;
126
127	/* get entry */
128	e = qe->entry;
129	if (e == NULL)
130		return -1;
131
132	template_name = (e->template_desc->name[0] != '\0') ?
133	    e->template_desc->name : e->template_desc->fmt;
134
135	/*
136	 * 1st: PCRIndex
137	 * PCR used is always the same (config option) in
138	 * little-endian format
139	 */
140	ima_putc(m, &pcr, sizeof(pcr));
141
142	/* 2nd: template digest */
143	ima_putc(m, e->digest, TPM_DIGEST_SIZE);
144
145	/* 3rd: template name size */
146	namelen = strlen(template_name);
147	ima_putc(m, &namelen, sizeof(namelen));
148
149	/* 4th:  template name */
150	ima_putc(m, template_name, namelen);
151
152	/* 5th:  template length (except for 'ima' template) */
153	if (strcmp(template_name, IMA_TEMPLATE_IMA_NAME) == 0)
154		is_ima_template = true;
155
156	if (!is_ima_template)
157		ima_putc(m, &e->template_data_len,
158			 sizeof(e->template_data_len));
159
160	/* 6th:  template specific data */
161	for (i = 0; i < e->template_desc->num_fields; i++) {
162		enum ima_show_type show = IMA_SHOW_BINARY;
163		struct ima_template_field *field = e->template_desc->fields[i];
164
165		if (is_ima_template && strcmp(field->field_id, "d") == 0)
166			show = IMA_SHOW_BINARY_NO_FIELD_LEN;
167		if (is_ima_template && strcmp(field->field_id, "n") == 0)
168			show = IMA_SHOW_BINARY_OLD_STRING_FMT;
169		field->field_show(m, show, &e->template_data[i]);
170	}
171	return 0;
172}
173
174static const struct seq_operations ima_measurments_seqops = {
175	.start = ima_measurements_start,
176	.next = ima_measurements_next,
177	.stop = ima_measurements_stop,
178	.show = ima_measurements_show
179};
180
181static int ima_measurements_open(struct inode *inode, struct file *file)
182{
183	return seq_open(file, &ima_measurments_seqops);
184}
185
186static const struct file_operations ima_measurements_ops = {
187	.open = ima_measurements_open,
188	.read = seq_read,
189	.llseek = seq_lseek,
190	.release = seq_release,
191};
192
193void ima_print_digest(struct seq_file *m, u8 *digest, u32 size)
194{
195	u32 i;
196
197	for (i = 0; i < size; i++)
198		seq_printf(m, "%02x", *(digest + i));
199}
200
201/* print in ascii */
202static int ima_ascii_measurements_show(struct seq_file *m, void *v)
203{
204	/* the list never shrinks, so we don't need a lock here */
205	struct ima_queue_entry *qe = v;
206	struct ima_template_entry *e;
207	char *template_name;
208	int i;
209
210	/* get entry */
211	e = qe->entry;
212	if (e == NULL)
213		return -1;
214
215	template_name = (e->template_desc->name[0] != '\0') ?
216	    e->template_desc->name : e->template_desc->fmt;
217
218	/* 1st: PCR used (config option) */
219	seq_printf(m, "%2d ", CONFIG_IMA_MEASURE_PCR_IDX);
220
221	/* 2nd: SHA1 template hash */
222	ima_print_digest(m, e->digest, TPM_DIGEST_SIZE);
223
224	/* 3th:  template name */
225	seq_printf(m, " %s", template_name);
226
227	/* 4th:  template specific data */
228	for (i = 0; i < e->template_desc->num_fields; i++) {
229		seq_puts(m, " ");
230		if (e->template_data[i].len == 0)
231			continue;
232
233		e->template_desc->fields[i]->field_show(m, IMA_SHOW_ASCII,
234							&e->template_data[i]);
235	}
236	seq_puts(m, "\n");
237	return 0;
238}
239
240static const struct seq_operations ima_ascii_measurements_seqops = {
241	.start = ima_measurements_start,
242	.next = ima_measurements_next,
243	.stop = ima_measurements_stop,
244	.show = ima_ascii_measurements_show
245};
246
247static int ima_ascii_measurements_open(struct inode *inode, struct file *file)
248{
249	return seq_open(file, &ima_ascii_measurements_seqops);
250}
251
252static const struct file_operations ima_ascii_measurements_ops = {
253	.open = ima_ascii_measurements_open,
254	.read = seq_read,
255	.llseek = seq_lseek,
256	.release = seq_release,
257};
258
259static ssize_t ima_write_policy(struct file *file, const char __user *buf,
260				size_t datalen, loff_t *ppos)
261{
262	char *data = NULL;
263	ssize_t result;
264
265	if (datalen >= PAGE_SIZE)
266		datalen = PAGE_SIZE - 1;
267
268	/* No partial writes. */
269	result = -EINVAL;
270	if (*ppos != 0)
271		goto out;
272
273	result = -ENOMEM;
274	data = kmalloc(datalen + 1, GFP_KERNEL);
275	if (!data)
276		goto out;
277
278	*(data + datalen) = '\0';
279
280	result = -EFAULT;
281	if (copy_from_user(data, buf, datalen))
282		goto out;
283
284	result = ima_parse_add_rule(data);
285out:
286	if (result < 0)
287		valid_policy = 0;
288	kfree(data);
289	return result;
290}
291
292static struct dentry *ima_dir;
293static struct dentry *binary_runtime_measurements;
294static struct dentry *ascii_runtime_measurements;
295static struct dentry *runtime_measurements_count;
296static struct dentry *violations;
297static struct dentry *ima_policy;
298
299enum ima_fs_flags {
300	IMA_FS_BUSY,
301};
302
303static unsigned long ima_fs_flags;
304
305/*
306 * ima_open_policy: sequentialize access to the policy file
307 */
308static int ima_open_policy(struct inode *inode, struct file *filp)
309{
310	/* No point in being allowed to open it if you aren't going to write */
311	if (!(filp->f_flags & O_WRONLY))
312		return -EACCES;
313	if (test_and_set_bit(IMA_FS_BUSY, &ima_fs_flags))
314		return -EBUSY;
315	return 0;
316}
317
318/*
319 * ima_release_policy - start using the new measure policy rules.
320 *
321 * Initially, ima_measure points to the default policy rules, now
322 * point to the new policy rules, and remove the securityfs policy file,
323 * assuming a valid policy.
324 */
325static int ima_release_policy(struct inode *inode, struct file *file)
326{
327	const char *cause = valid_policy ? "completed" : "failed";
328
329	pr_info("IMA: policy update %s\n", cause);
330	integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL, NULL,
331			    "policy_update", cause, !valid_policy, 0);
332
333	if (!valid_policy) {
334		ima_delete_rules();
335		valid_policy = 1;
336		clear_bit(IMA_FS_BUSY, &ima_fs_flags);
337		return 0;
338	}
339	ima_update_policy();
340	securityfs_remove(ima_policy);
341	ima_policy = NULL;
342	return 0;
343}
344
345static const struct file_operations ima_measure_policy_ops = {
346	.open = ima_open_policy,
347	.write = ima_write_policy,
348	.release = ima_release_policy,
349	.llseek = generic_file_llseek,
350};
351
352int __init ima_fs_init(void)
353{
354	ima_dir = securityfs_create_dir("ima", NULL);
355	if (IS_ERR(ima_dir))
356		return -1;
357
358	binary_runtime_measurements =
359	    securityfs_create_file("binary_runtime_measurements",
360				   S_IRUSR | S_IRGRP, ima_dir, NULL,
361				   &ima_measurements_ops);
362	if (IS_ERR(binary_runtime_measurements))
363		goto out;
364
365	ascii_runtime_measurements =
366	    securityfs_create_file("ascii_runtime_measurements",
367				   S_IRUSR | S_IRGRP, ima_dir, NULL,
368				   &ima_ascii_measurements_ops);
369	if (IS_ERR(ascii_runtime_measurements))
370		goto out;
371
372	runtime_measurements_count =
373	    securityfs_create_file("runtime_measurements_count",
374				   S_IRUSR | S_IRGRP, ima_dir, NULL,
375				   &ima_measurements_count_ops);
376	if (IS_ERR(runtime_measurements_count))
377		goto out;
378
379	violations =
380	    securityfs_create_file("violations", S_IRUSR | S_IRGRP,
381				   ima_dir, NULL, &ima_htable_violations_ops);
382	if (IS_ERR(violations))
383		goto out;
384
385	ima_policy = securityfs_create_file("policy",
386					    S_IWUSR,
387					    ima_dir, NULL,
388					    &ima_measure_policy_ops);
389	if (IS_ERR(ima_policy))
390		goto out;
391
392	return 0;
393out:
394	securityfs_remove(violations);
395	securityfs_remove(runtime_measurements_count);
396	securityfs_remove(ascii_runtime_measurements);
397	securityfs_remove(binary_runtime_measurements);
398	securityfs_remove(ima_dir);
399	securityfs_remove(ima_policy);
400	return -1;
401}
402