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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 | */ | |
f850a7c0 | 18 | #include <linux/fcntl.h> |
5a0e3ad6 | 19 | #include <linux/slab.h> |
bab73937 MZ |
20 | #include <linux/module.h> |
21 | #include <linux/seq_file.h> | |
22 | #include <linux/rculist.h> | |
23 | #include <linux/rcupdate.h> | |
4af4662f | 24 | #include <linux/parser.h> |
bab73937 MZ |
25 | |
26 | #include "ima.h" | |
27 | ||
4af4662f | 28 | static int valid_policy = 1; |
bab73937 MZ |
29 | #define TMPBUFLEN 12 |
30 | static 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 | ||
40 | static 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 | ||
828c0950 | 47 | static const struct file_operations ima_htable_violations_ops = { |
bab73937 MZ |
48 | .read = ima_show_htable_violations |
49 | }; | |
50 | ||
51 | static ssize_t ima_show_measurements_count(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.len); | |
56 | ||
57 | } | |
58 | ||
828c0950 | 59 | static const struct file_operations ima_measurements_count_ops = { |
bab73937 MZ |
60 | .read = ima_show_measurements_count |
61 | }; | |
62 | ||
63 | /* returns pointer to hlist_node */ | |
64 | static void *ima_measurements_start(struct seq_file *m, loff_t *pos) | |
65 | { | |
66 | loff_t l = *pos; | |
67 | struct ima_queue_entry *qe; | |
68 | ||
69 | /* we need a lock since pos could point beyond last element */ | |
70 | rcu_read_lock(); | |
71 | list_for_each_entry_rcu(qe, &ima_measurements, later) { | |
72 | if (!l--) { | |
73 | rcu_read_unlock(); | |
74 | return qe; | |
75 | } | |
76 | } | |
77 | rcu_read_unlock(); | |
78 | return NULL; | |
79 | } | |
80 | ||
81 | static void *ima_measurements_next(struct seq_file *m, void *v, loff_t *pos) | |
82 | { | |
83 | struct ima_queue_entry *qe = v; | |
84 | ||
85 | /* lock protects when reading beyond last element | |
86 | * against concurrent list-extension | |
87 | */ | |
88 | rcu_read_lock(); | |
05725f7e JP |
89 | qe = list_entry_rcu(qe->later.next, |
90 | struct ima_queue_entry, later); | |
bab73937 MZ |
91 | rcu_read_unlock(); |
92 | (*pos)++; | |
93 | ||
94 | return (&qe->later == &ima_measurements) ? NULL : qe; | |
95 | } | |
96 | ||
97 | static void ima_measurements_stop(struct seq_file *m, void *v) | |
98 | { | |
99 | } | |
100 | ||
101 | static void ima_putc(struct seq_file *m, void *data, int datalen) | |
102 | { | |
103 | while (datalen--) | |
104 | seq_putc(m, *(char *)data++); | |
105 | } | |
106 | ||
107 | /* print format: | |
108 | * 32bit-le=pcr# | |
109 | * char[20]=template digest | |
110 | * 32bit-le=template name size | |
111 | * char[n]=template name | |
112 | * eventdata[n]=template specific data | |
113 | */ | |
114 | static int ima_measurements_show(struct seq_file *m, void *v) | |
115 | { | |
116 | /* the list never shrinks, so we don't need a lock here */ | |
117 | struct ima_queue_entry *qe = v; | |
118 | struct ima_template_entry *e; | |
119 | int namelen; | |
120 | u32 pcr = CONFIG_IMA_MEASURE_PCR_IDX; | |
121 | ||
122 | /* get entry */ | |
123 | e = qe->entry; | |
124 | if (e == NULL) | |
125 | return -1; | |
126 | ||
127 | /* | |
128 | * 1st: PCRIndex | |
129 | * PCR used is always the same (config option) in | |
130 | * little-endian format | |
131 | */ | |
132 | ima_putc(m, &pcr, sizeof pcr); | |
133 | ||
134 | /* 2nd: template digest */ | |
135 | ima_putc(m, e->digest, IMA_DIGEST_SIZE); | |
136 | ||
137 | /* 3rd: template name size */ | |
138 | namelen = strlen(e->template_name); | |
139 | ima_putc(m, &namelen, sizeof namelen); | |
140 | ||
141 | /* 4th: template name */ | |
523979ad | 142 | ima_putc(m, (void *)e->template_name, namelen); |
bab73937 MZ |
143 | |
144 | /* 5th: template specific data */ | |
145 | ima_template_show(m, (struct ima_template_data *)&e->template, | |
146 | IMA_SHOW_BINARY); | |
147 | return 0; | |
148 | } | |
149 | ||
88e9d34c | 150 | static const struct seq_operations ima_measurments_seqops = { |
bab73937 MZ |
151 | .start = ima_measurements_start, |
152 | .next = ima_measurements_next, | |
153 | .stop = ima_measurements_stop, | |
154 | .show = ima_measurements_show | |
155 | }; | |
156 | ||
157 | static int ima_measurements_open(struct inode *inode, struct file *file) | |
158 | { | |
159 | return seq_open(file, &ima_measurments_seqops); | |
160 | } | |
161 | ||
828c0950 | 162 | static const struct file_operations ima_measurements_ops = { |
bab73937 MZ |
163 | .open = ima_measurements_open, |
164 | .read = seq_read, | |
165 | .llseek = seq_lseek, | |
166 | .release = seq_release, | |
167 | }; | |
168 | ||
169 | static void ima_print_digest(struct seq_file *m, u8 *digest) | |
170 | { | |
171 | int i; | |
172 | ||
173 | for (i = 0; i < IMA_DIGEST_SIZE; i++) | |
174 | seq_printf(m, "%02x", *(digest + i)); | |
175 | } | |
176 | ||
177 | void ima_template_show(struct seq_file *m, void *e, enum ima_show_type show) | |
178 | { | |
179 | struct ima_template_data *entry = e; | |
180 | int namelen; | |
181 | ||
182 | switch (show) { | |
183 | case IMA_SHOW_ASCII: | |
184 | ima_print_digest(m, entry->digest); | |
185 | seq_printf(m, " %s\n", entry->file_name); | |
186 | break; | |
187 | case IMA_SHOW_BINARY: | |
188 | ima_putc(m, entry->digest, IMA_DIGEST_SIZE); | |
189 | ||
190 | namelen = strlen(entry->file_name); | |
191 | ima_putc(m, &namelen, sizeof namelen); | |
192 | ima_putc(m, entry->file_name, namelen); | |
193 | default: | |
194 | break; | |
195 | } | |
196 | } | |
197 | ||
198 | /* print in ascii */ | |
199 | static int ima_ascii_measurements_show(struct seq_file *m, void *v) | |
200 | { | |
201 | /* the list never shrinks, so we don't need a lock here */ | |
202 | struct ima_queue_entry *qe = v; | |
203 | struct ima_template_entry *e; | |
204 | ||
205 | /* get entry */ | |
206 | e = qe->entry; | |
207 | if (e == NULL) | |
208 | return -1; | |
209 | ||
210 | /* 1st: PCR used (config option) */ | |
211 | seq_printf(m, "%2d ", CONFIG_IMA_MEASURE_PCR_IDX); | |
212 | ||
213 | /* 2nd: SHA1 template hash */ | |
214 | ima_print_digest(m, e->digest); | |
215 | ||
216 | /* 3th: template name */ | |
217 | seq_printf(m, " %s ", e->template_name); | |
218 | ||
219 | /* 4th: template specific data */ | |
220 | ima_template_show(m, (struct ima_template_data *)&e->template, | |
221 | IMA_SHOW_ASCII); | |
222 | return 0; | |
223 | } | |
224 | ||
88e9d34c | 225 | static const struct seq_operations ima_ascii_measurements_seqops = { |
bab73937 MZ |
226 | .start = ima_measurements_start, |
227 | .next = ima_measurements_next, | |
228 | .stop = ima_measurements_stop, | |
229 | .show = ima_ascii_measurements_show | |
230 | }; | |
231 | ||
232 | static int ima_ascii_measurements_open(struct inode *inode, struct file *file) | |
233 | { | |
234 | return seq_open(file, &ima_ascii_measurements_seqops); | |
235 | } | |
236 | ||
828c0950 | 237 | static const struct file_operations ima_ascii_measurements_ops = { |
bab73937 MZ |
238 | .open = ima_ascii_measurements_open, |
239 | .read = seq_read, | |
240 | .llseek = seq_lseek, | |
241 | .release = seq_release, | |
242 | }; | |
243 | ||
4af4662f MZ |
244 | static ssize_t ima_write_policy(struct file *file, const char __user *buf, |
245 | size_t datalen, loff_t *ppos) | |
246 | { | |
6ccd0456 EP |
247 | char *data = NULL; |
248 | ssize_t result; | |
4af4662f MZ |
249 | |
250 | if (datalen >= PAGE_SIZE) | |
6ccd0456 EP |
251 | datalen = PAGE_SIZE - 1; |
252 | ||
253 | /* No partial writes. */ | |
254 | result = -EINVAL; | |
255 | if (*ppos != 0) | |
256 | goto out; | |
257 | ||
258 | result = -ENOMEM; | |
4af4662f MZ |
259 | data = kmalloc(datalen + 1, GFP_KERNEL); |
260 | if (!data) | |
6ccd0456 | 261 | goto out; |
4af4662f | 262 | |
4af4662f | 263 | *(data + datalen) = '\0'; |
4af4662f | 264 | |
6ccd0456 EP |
265 | result = -EFAULT; |
266 | if (copy_from_user(data, buf, datalen)) | |
267 | goto out; | |
268 | ||
269 | result = ima_parse_add_rule(data); | |
270 | out: | |
271 | if (result < 0) | |
272 | valid_policy = 0; | |
4af4662f | 273 | kfree(data); |
6ccd0456 | 274 | return result; |
4af4662f MZ |
275 | } |
276 | ||
bab73937 MZ |
277 | static struct dentry *ima_dir; |
278 | static struct dentry *binary_runtime_measurements; | |
279 | static struct dentry *ascii_runtime_measurements; | |
280 | static struct dentry *runtime_measurements_count; | |
281 | static struct dentry *violations; | |
4af4662f MZ |
282 | static struct dentry *ima_policy; |
283 | ||
f4bd857b MZ |
284 | static atomic_t policy_opencount = ATOMIC_INIT(1); |
285 | /* | |
286 | * ima_open_policy: sequentialize access to the policy file | |
287 | */ | |
288 | int ima_open_policy(struct inode * inode, struct file * filp) | |
289 | { | |
f850a7c0 EP |
290 | /* No point in being allowed to open it if you aren't going to write */ |
291 | if (!(filp->f_flags & O_WRONLY)) | |
292 | return -EACCES; | |
f4bd857b MZ |
293 | if (atomic_dec_and_test(&policy_opencount)) |
294 | return 0; | |
295 | return -EBUSY; | |
296 | } | |
297 | ||
4af4662f MZ |
298 | /* |
299 | * ima_release_policy - start using the new measure policy rules. | |
300 | * | |
301 | * Initially, ima_measure points to the default policy rules, now | |
f4bd857b MZ |
302 | * point to the new policy rules, and remove the securityfs policy file, |
303 | * assuming a valid policy. | |
4af4662f MZ |
304 | */ |
305 | static int ima_release_policy(struct inode *inode, struct file *file) | |
306 | { | |
307 | if (!valid_policy) { | |
308 | ima_delete_rules(); | |
f4bd857b MZ |
309 | valid_policy = 1; |
310 | atomic_set(&policy_opencount, 1); | |
4af4662f MZ |
311 | return 0; |
312 | } | |
313 | ima_update_policy(); | |
314 | securityfs_remove(ima_policy); | |
315 | ima_policy = NULL; | |
316 | return 0; | |
317 | } | |
318 | ||
828c0950 | 319 | static const struct file_operations ima_measure_policy_ops = { |
f4bd857b | 320 | .open = ima_open_policy, |
4af4662f MZ |
321 | .write = ima_write_policy, |
322 | .release = ima_release_policy | |
323 | }; | |
bab73937 | 324 | |
932995f0 | 325 | int __init ima_fs_init(void) |
bab73937 MZ |
326 | { |
327 | ima_dir = securityfs_create_dir("ima", NULL); | |
328 | if (IS_ERR(ima_dir)) | |
329 | return -1; | |
330 | ||
331 | binary_runtime_measurements = | |
332 | securityfs_create_file("binary_runtime_measurements", | |
333 | S_IRUSR | S_IRGRP, ima_dir, NULL, | |
334 | &ima_measurements_ops); | |
335 | if (IS_ERR(binary_runtime_measurements)) | |
336 | goto out; | |
337 | ||
338 | ascii_runtime_measurements = | |
339 | securityfs_create_file("ascii_runtime_measurements", | |
340 | S_IRUSR | S_IRGRP, ima_dir, NULL, | |
341 | &ima_ascii_measurements_ops); | |
342 | if (IS_ERR(ascii_runtime_measurements)) | |
343 | goto out; | |
344 | ||
345 | runtime_measurements_count = | |
346 | securityfs_create_file("runtime_measurements_count", | |
347 | S_IRUSR | S_IRGRP, ima_dir, NULL, | |
348 | &ima_measurements_count_ops); | |
349 | if (IS_ERR(runtime_measurements_count)) | |
350 | goto out; | |
351 | ||
352 | violations = | |
353 | securityfs_create_file("violations", S_IRUSR | S_IRGRP, | |
354 | ima_dir, NULL, &ima_htable_violations_ops); | |
355 | if (IS_ERR(violations)) | |
356 | goto out; | |
357 | ||
4af4662f | 358 | ima_policy = securityfs_create_file("policy", |
f850a7c0 | 359 | S_IWUSR, |
4af4662f MZ |
360 | ima_dir, NULL, |
361 | &ima_measure_policy_ops); | |
362 | if (IS_ERR(ima_policy)) | |
363 | goto out; | |
bab73937 | 364 | |
4af4662f | 365 | return 0; |
bab73937 MZ |
366 | out: |
367 | securityfs_remove(runtime_measurements_count); | |
368 | securityfs_remove(ascii_runtime_measurements); | |
369 | securityfs_remove(binary_runtime_measurements); | |
370 | securityfs_remove(ima_dir); | |
4af4662f | 371 | securityfs_remove(ima_policy); |
bab73937 MZ |
372 | return -1; |
373 | } | |
374 | ||
375 | void __exit ima_fs_cleanup(void) | |
376 | { | |
377 | securityfs_remove(violations); | |
378 | securityfs_remove(runtime_measurements_count); | |
379 | securityfs_remove(ascii_runtime_measurements); | |
380 | securityfs_remove(binary_runtime_measurements); | |
381 | securityfs_remove(ima_dir); | |
4af4662f | 382 | securityfs_remove(ima_policy); |
bab73937 | 383 | } |