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bab73937 MZ |
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/module.h> | |
19 | #include <linux/seq_file.h> | |
20 | #include <linux/rculist.h> | |
21 | #include <linux/rcupdate.h> | |
4af4662f | 22 | #include <linux/parser.h> |
bab73937 MZ |
23 | |
24 | #include "ima.h" | |
25 | ||
4af4662f | 26 | static int valid_policy = 1; |
bab73937 MZ |
27 | #define TMPBUFLEN 12 |
28 | static ssize_t ima_show_htable_value(char __user *buf, size_t count, | |
29 | loff_t *ppos, atomic_long_t *val) | |
30 | { | |
31 | char tmpbuf[TMPBUFLEN]; | |
32 | ssize_t len; | |
33 | ||
34 | len = scnprintf(tmpbuf, TMPBUFLEN, "%li\n", atomic_long_read(val)); | |
35 | return simple_read_from_buffer(buf, count, ppos, tmpbuf, len); | |
36 | } | |
37 | ||
38 | static ssize_t ima_show_htable_violations(struct file *filp, | |
39 | char __user *buf, | |
40 | size_t count, loff_t *ppos) | |
41 | { | |
42 | return ima_show_htable_value(buf, count, ppos, &ima_htable.violations); | |
43 | } | |
44 | ||
45 | static struct file_operations ima_htable_violations_ops = { | |
46 | .read = ima_show_htable_violations | |
47 | }; | |
48 | ||
49 | static ssize_t ima_show_measurements_count(struct file *filp, | |
50 | char __user *buf, | |
51 | size_t count, loff_t *ppos) | |
52 | { | |
53 | return ima_show_htable_value(buf, count, ppos, &ima_htable.len); | |
54 | ||
55 | } | |
56 | ||
57 | static struct file_operations ima_measurements_count_ops = { | |
58 | .read = ima_show_measurements_count | |
59 | }; | |
60 | ||
61 | /* returns pointer to hlist_node */ | |
62 | static void *ima_measurements_start(struct seq_file *m, loff_t *pos) | |
63 | { | |
64 | loff_t l = *pos; | |
65 | struct ima_queue_entry *qe; | |
66 | ||
67 | /* we need a lock since pos could point beyond last element */ | |
68 | rcu_read_lock(); | |
69 | list_for_each_entry_rcu(qe, &ima_measurements, later) { | |
70 | if (!l--) { | |
71 | rcu_read_unlock(); | |
72 | return qe; | |
73 | } | |
74 | } | |
75 | rcu_read_unlock(); | |
76 | return NULL; | |
77 | } | |
78 | ||
79 | static void *ima_measurements_next(struct seq_file *m, void *v, loff_t *pos) | |
80 | { | |
81 | struct ima_queue_entry *qe = v; | |
82 | ||
83 | /* lock protects when reading beyond last element | |
84 | * against concurrent list-extension | |
85 | */ | |
86 | rcu_read_lock(); | |
05725f7e JP |
87 | qe = list_entry_rcu(qe->later.next, |
88 | struct ima_queue_entry, later); | |
bab73937 MZ |
89 | rcu_read_unlock(); |
90 | (*pos)++; | |
91 | ||
92 | return (&qe->later == &ima_measurements) ? NULL : qe; | |
93 | } | |
94 | ||
95 | static void ima_measurements_stop(struct seq_file *m, void *v) | |
96 | { | |
97 | } | |
98 | ||
99 | static void ima_putc(struct seq_file *m, void *data, int datalen) | |
100 | { | |
101 | while (datalen--) | |
102 | seq_putc(m, *(char *)data++); | |
103 | } | |
104 | ||
105 | /* print format: | |
106 | * 32bit-le=pcr# | |
107 | * char[20]=template digest | |
108 | * 32bit-le=template name size | |
109 | * char[n]=template name | |
110 | * eventdata[n]=template specific data | |
111 | */ | |
112 | static int ima_measurements_show(struct seq_file *m, void *v) | |
113 | { | |
114 | /* the list never shrinks, so we don't need a lock here */ | |
115 | struct ima_queue_entry *qe = v; | |
116 | struct ima_template_entry *e; | |
117 | int namelen; | |
118 | u32 pcr = CONFIG_IMA_MEASURE_PCR_IDX; | |
119 | ||
120 | /* get entry */ | |
121 | e = qe->entry; | |
122 | if (e == NULL) | |
123 | return -1; | |
124 | ||
125 | /* | |
126 | * 1st: PCRIndex | |
127 | * PCR used is always the same (config option) in | |
128 | * little-endian format | |
129 | */ | |
130 | ima_putc(m, &pcr, sizeof pcr); | |
131 | ||
132 | /* 2nd: template digest */ | |
133 | ima_putc(m, e->digest, IMA_DIGEST_SIZE); | |
134 | ||
135 | /* 3rd: template name size */ | |
136 | namelen = strlen(e->template_name); | |
137 | ima_putc(m, &namelen, sizeof namelen); | |
138 | ||
139 | /* 4th: template name */ | |
523979ad | 140 | ima_putc(m, (void *)e->template_name, namelen); |
bab73937 MZ |
141 | |
142 | /* 5th: template specific data */ | |
143 | ima_template_show(m, (struct ima_template_data *)&e->template, | |
144 | IMA_SHOW_BINARY); | |
145 | return 0; | |
146 | } | |
147 | ||
148 | static struct seq_operations ima_measurments_seqops = { | |
149 | .start = ima_measurements_start, | |
150 | .next = ima_measurements_next, | |
151 | .stop = ima_measurements_stop, | |
152 | .show = ima_measurements_show | |
153 | }; | |
154 | ||
155 | static int ima_measurements_open(struct inode *inode, struct file *file) | |
156 | { | |
157 | return seq_open(file, &ima_measurments_seqops); | |
158 | } | |
159 | ||
160 | static struct file_operations ima_measurements_ops = { | |
161 | .open = ima_measurements_open, | |
162 | .read = seq_read, | |
163 | .llseek = seq_lseek, | |
164 | .release = seq_release, | |
165 | }; | |
166 | ||
167 | static void ima_print_digest(struct seq_file *m, u8 *digest) | |
168 | { | |
169 | int i; | |
170 | ||
171 | for (i = 0; i < IMA_DIGEST_SIZE; i++) | |
172 | seq_printf(m, "%02x", *(digest + i)); | |
173 | } | |
174 | ||
175 | void ima_template_show(struct seq_file *m, void *e, enum ima_show_type show) | |
176 | { | |
177 | struct ima_template_data *entry = e; | |
178 | int namelen; | |
179 | ||
180 | switch (show) { | |
181 | case IMA_SHOW_ASCII: | |
182 | ima_print_digest(m, entry->digest); | |
183 | seq_printf(m, " %s\n", entry->file_name); | |
184 | break; | |
185 | case IMA_SHOW_BINARY: | |
186 | ima_putc(m, entry->digest, IMA_DIGEST_SIZE); | |
187 | ||
188 | namelen = strlen(entry->file_name); | |
189 | ima_putc(m, &namelen, sizeof namelen); | |
190 | ima_putc(m, entry->file_name, namelen); | |
191 | default: | |
192 | break; | |
193 | } | |
194 | } | |
195 | ||
196 | /* print in ascii */ | |
197 | static int ima_ascii_measurements_show(struct seq_file *m, void *v) | |
198 | { | |
199 | /* the list never shrinks, so we don't need a lock here */ | |
200 | struct ima_queue_entry *qe = v; | |
201 | struct ima_template_entry *e; | |
202 | ||
203 | /* get entry */ | |
204 | e = qe->entry; | |
205 | if (e == NULL) | |
206 | return -1; | |
207 | ||
208 | /* 1st: PCR used (config option) */ | |
209 | seq_printf(m, "%2d ", CONFIG_IMA_MEASURE_PCR_IDX); | |
210 | ||
211 | /* 2nd: SHA1 template hash */ | |
212 | ima_print_digest(m, e->digest); | |
213 | ||
214 | /* 3th: template name */ | |
215 | seq_printf(m, " %s ", e->template_name); | |
216 | ||
217 | /* 4th: template specific data */ | |
218 | ima_template_show(m, (struct ima_template_data *)&e->template, | |
219 | IMA_SHOW_ASCII); | |
220 | return 0; | |
221 | } | |
222 | ||
223 | static struct seq_operations ima_ascii_measurements_seqops = { | |
224 | .start = ima_measurements_start, | |
225 | .next = ima_measurements_next, | |
226 | .stop = ima_measurements_stop, | |
227 | .show = ima_ascii_measurements_show | |
228 | }; | |
229 | ||
230 | static int ima_ascii_measurements_open(struct inode *inode, struct file *file) | |
231 | { | |
232 | return seq_open(file, &ima_ascii_measurements_seqops); | |
233 | } | |
234 | ||
235 | static struct file_operations ima_ascii_measurements_ops = { | |
236 | .open = ima_ascii_measurements_open, | |
237 | .read = seq_read, | |
238 | .llseek = seq_lseek, | |
239 | .release = seq_release, | |
240 | }; | |
241 | ||
4af4662f MZ |
242 | static ssize_t ima_write_policy(struct file *file, const char __user *buf, |
243 | size_t datalen, loff_t *ppos) | |
244 | { | |
245 | char *data; | |
246 | int rc; | |
247 | ||
248 | if (datalen >= PAGE_SIZE) | |
249 | return -ENOMEM; | |
250 | if (*ppos != 0) { | |
251 | /* No partial writes. */ | |
252 | return -EINVAL; | |
253 | } | |
254 | data = kmalloc(datalen + 1, GFP_KERNEL); | |
255 | if (!data) | |
256 | return -ENOMEM; | |
257 | ||
258 | if (copy_from_user(data, buf, datalen)) { | |
259 | kfree(data); | |
260 | return -EFAULT; | |
261 | } | |
262 | *(data + datalen) = '\0'; | |
263 | rc = ima_parse_add_rule(data); | |
264 | if (rc < 0) { | |
265 | datalen = -EINVAL; | |
266 | valid_policy = 0; | |
267 | } | |
268 | ||
269 | kfree(data); | |
270 | return datalen; | |
271 | } | |
272 | ||
bab73937 MZ |
273 | static struct dentry *ima_dir; |
274 | static struct dentry *binary_runtime_measurements; | |
275 | static struct dentry *ascii_runtime_measurements; | |
276 | static struct dentry *runtime_measurements_count; | |
277 | static struct dentry *violations; | |
4af4662f MZ |
278 | static struct dentry *ima_policy; |
279 | ||
f4bd857b MZ |
280 | static atomic_t policy_opencount = ATOMIC_INIT(1); |
281 | /* | |
282 | * ima_open_policy: sequentialize access to the policy file | |
283 | */ | |
284 | int ima_open_policy(struct inode * inode, struct file * filp) | |
285 | { | |
286 | if (atomic_dec_and_test(&policy_opencount)) | |
287 | return 0; | |
288 | return -EBUSY; | |
289 | } | |
290 | ||
4af4662f MZ |
291 | /* |
292 | * ima_release_policy - start using the new measure policy rules. | |
293 | * | |
294 | * Initially, ima_measure points to the default policy rules, now | |
f4bd857b MZ |
295 | * point to the new policy rules, and remove the securityfs policy file, |
296 | * assuming a valid policy. | |
4af4662f MZ |
297 | */ |
298 | static int ima_release_policy(struct inode *inode, struct file *file) | |
299 | { | |
300 | if (!valid_policy) { | |
301 | ima_delete_rules(); | |
f4bd857b MZ |
302 | valid_policy = 1; |
303 | atomic_set(&policy_opencount, 1); | |
4af4662f MZ |
304 | return 0; |
305 | } | |
306 | ima_update_policy(); | |
307 | securityfs_remove(ima_policy); | |
308 | ima_policy = NULL; | |
309 | return 0; | |
310 | } | |
311 | ||
312 | static struct file_operations ima_measure_policy_ops = { | |
f4bd857b | 313 | .open = ima_open_policy, |
4af4662f MZ |
314 | .write = ima_write_policy, |
315 | .release = ima_release_policy | |
316 | }; | |
bab73937 MZ |
317 | |
318 | int ima_fs_init(void) | |
319 | { | |
320 | ima_dir = securityfs_create_dir("ima", NULL); | |
321 | if (IS_ERR(ima_dir)) | |
322 | return -1; | |
323 | ||
324 | binary_runtime_measurements = | |
325 | securityfs_create_file("binary_runtime_measurements", | |
326 | S_IRUSR | S_IRGRP, ima_dir, NULL, | |
327 | &ima_measurements_ops); | |
328 | if (IS_ERR(binary_runtime_measurements)) | |
329 | goto out; | |
330 | ||
331 | ascii_runtime_measurements = | |
332 | securityfs_create_file("ascii_runtime_measurements", | |
333 | S_IRUSR | S_IRGRP, ima_dir, NULL, | |
334 | &ima_ascii_measurements_ops); | |
335 | if (IS_ERR(ascii_runtime_measurements)) | |
336 | goto out; | |
337 | ||
338 | runtime_measurements_count = | |
339 | securityfs_create_file("runtime_measurements_count", | |
340 | S_IRUSR | S_IRGRP, ima_dir, NULL, | |
341 | &ima_measurements_count_ops); | |
342 | if (IS_ERR(runtime_measurements_count)) | |
343 | goto out; | |
344 | ||
345 | violations = | |
346 | securityfs_create_file("violations", S_IRUSR | S_IRGRP, | |
347 | ima_dir, NULL, &ima_htable_violations_ops); | |
348 | if (IS_ERR(violations)) | |
349 | goto out; | |
350 | ||
4af4662f MZ |
351 | ima_policy = securityfs_create_file("policy", |
352 | S_IRUSR | S_IRGRP | S_IWUSR, | |
353 | ima_dir, NULL, | |
354 | &ima_measure_policy_ops); | |
355 | if (IS_ERR(ima_policy)) | |
356 | goto out; | |
bab73937 | 357 | |
4af4662f | 358 | return 0; |
bab73937 MZ |
359 | out: |
360 | securityfs_remove(runtime_measurements_count); | |
361 | securityfs_remove(ascii_runtime_measurements); | |
362 | securityfs_remove(binary_runtime_measurements); | |
363 | securityfs_remove(ima_dir); | |
4af4662f | 364 | securityfs_remove(ima_policy); |
bab73937 MZ |
365 | return -1; |
366 | } | |
367 | ||
368 | void __exit ima_fs_cleanup(void) | |
369 | { | |
370 | securityfs_remove(violations); | |
371 | securityfs_remove(runtime_measurements_count); | |
372 | securityfs_remove(ascii_runtime_measurements); | |
373 | securityfs_remove(binary_runtime_measurements); | |
374 | securityfs_remove(ima_dir); | |
4af4662f | 375 | securityfs_remove(ima_policy); |
bab73937 | 376 | } |