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Commit | Line | Data |
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3323eec9 MZ |
1 | /* |
2 | * Copyright (C) 2005,2006,2007,2008 IBM Corporation | |
3 | * | |
4 | * Authors: | |
5 | * Reiner Sailer <sailer@watson.ibm.com> | |
6 | * Serge Hallyn <serue@us.ibm.com> | |
7 | * Kylene Hall <kylene@us.ibm.com> | |
8 | * Mimi Zohar <zohar@us.ibm.com> | |
9 | * | |
10 | * This program is free software; you can redistribute it and/or | |
11 | * modify it under the terms of the GNU General Public License as | |
12 | * published by the Free Software Foundation, version 2 of the | |
13 | * License. | |
14 | * | |
15 | * File: ima_main.c | |
e0d5bd2a | 16 | * implements the IMA hooks: ima_bprm_check, ima_file_mmap, |
9bbb6cad | 17 | * and ima_file_check. |
3323eec9 | 18 | */ |
8a048adc PV |
19 | |
20 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt | |
21 | ||
3323eec9 MZ |
22 | #include <linux/module.h> |
23 | #include <linux/file.h> | |
24 | #include <linux/binfmts.h> | |
25 | #include <linux/mount.h> | |
26 | #include <linux/mman.h> | |
5a0e3ad6 | 27 | #include <linux/slab.h> |
2fe5d6de | 28 | #include <linux/xattr.h> |
d5813a57 | 29 | #include <linux/ima.h> |
3323eec9 MZ |
30 | |
31 | #include "ima.h" | |
32 | ||
33 | int ima_initialized; | |
34 | ||
2fe5d6de MZ |
35 | #ifdef CONFIG_IMA_APPRAISE |
36 | int ima_appraise = IMA_APPRAISE_ENFORCE; | |
37 | #else | |
38 | int ima_appraise; | |
39 | #endif | |
40 | ||
c7c8bb23 | 41 | int ima_hash_algo = HASH_ALGO_SHA1; |
e7a2ad7e | 42 | static int hash_setup_done; |
c7c8bb23 | 43 | |
3323eec9 MZ |
44 | static int __init hash_setup(char *str) |
45 | { | |
e7a2ad7e MZ |
46 | struct ima_template_desc *template_desc = ima_template_desc_current(); |
47 | int i; | |
48 | ||
49 | if (hash_setup_done) | |
50 | return 1; | |
51 | ||
52 | if (strcmp(template_desc->name, IMA_TEMPLATE_IMA_NAME) == 0) { | |
53 | if (strncmp(str, "sha1", 4) == 0) | |
54 | ima_hash_algo = HASH_ALGO_SHA1; | |
55 | else if (strncmp(str, "md5", 3) == 0) | |
56 | ima_hash_algo = HASH_ALGO_MD5; | |
ebe7c0a7 BW |
57 | else |
58 | return 1; | |
e7a2ad7e MZ |
59 | goto out; |
60 | } | |
61 | ||
62 | for (i = 0; i < HASH_ALGO__LAST; i++) { | |
63 | if (strcmp(str, hash_algo_name[i]) == 0) { | |
64 | ima_hash_algo = i; | |
65 | break; | |
66 | } | |
67 | } | |
ebe7c0a7 BW |
68 | if (i == HASH_ALGO__LAST) |
69 | return 1; | |
e7a2ad7e MZ |
70 | out: |
71 | hash_setup_done = 1; | |
3323eec9 MZ |
72 | return 1; |
73 | } | |
74 | __setup("ima_hash=", hash_setup); | |
75 | ||
8eb988c7 | 76 | /* |
890275b5 | 77 | * ima_rdwr_violation_check |
8eb988c7 | 78 | * |
890275b5 | 79 | * Only invalidate the PCR for measured files: |
2bb930ab | 80 | * - Opening a file for write when already open for read, |
8eb988c7 MZ |
81 | * results in a time of measure, time of use (ToMToU) error. |
82 | * - Opening a file for read when already open for write, | |
2bb930ab | 83 | * could result in a file measurement error. |
8eb988c7 MZ |
84 | * |
85 | */ | |
f7a859ff RS |
86 | static void ima_rdwr_violation_check(struct file *file, |
87 | struct integrity_iint_cache *iint, | |
1b68bdf9 | 88 | int must_measure, |
f7a859ff RS |
89 | char **pathbuf, |
90 | const char **pathname) | |
8eb988c7 | 91 | { |
c77cecee | 92 | struct inode *inode = file_inode(file); |
bc15ed66 | 93 | char filename[NAME_MAX]; |
8eb988c7 | 94 | fmode_t mode = file->f_mode; |
ad16ad00 | 95 | bool send_tomtou = false, send_writers = false; |
a178d202 | 96 | |
8eb988c7 | 97 | if (mode & FMODE_WRITE) { |
14503eb9 | 98 | if (atomic_read(&inode->i_readcount) && IS_IMA(inode)) { |
f7a859ff RS |
99 | if (!iint) |
100 | iint = integrity_iint_find(inode); | |
14503eb9 DK |
101 | /* IMA_MEASURE is set from reader side */ |
102 | if (iint && (iint->flags & IMA_MEASURE)) | |
103 | send_tomtou = true; | |
104 | } | |
b882fae2 | 105 | } else { |
1b68bdf9 | 106 | if ((atomic_read(&inode->i_writecount) > 0) && must_measure) |
b882fae2 | 107 | send_writers = true; |
8eb988c7 | 108 | } |
ad16ad00 | 109 | |
08e1b76a MZ |
110 | if (!send_tomtou && !send_writers) |
111 | return; | |
112 | ||
bc15ed66 | 113 | *pathname = ima_d_path(&file->f_path, pathbuf, filename); |
ea1046d4 | 114 | |
ad16ad00 | 115 | if (send_tomtou) |
8d94eb9b RS |
116 | ima_add_violation(file, *pathname, iint, |
117 | "invalid_pcr", "ToMToU"); | |
ad16ad00 | 118 | if (send_writers) |
8d94eb9b | 119 | ima_add_violation(file, *pathname, iint, |
08e1b76a | 120 | "invalid_pcr", "open_writers"); |
8eb988c7 MZ |
121 | } |
122 | ||
f381c272 | 123 | static void ima_check_last_writer(struct integrity_iint_cache *iint, |
2fe5d6de | 124 | struct inode *inode, struct file *file) |
bc7d2a3e | 125 | { |
4b2a2c67 | 126 | fmode_t mode = file->f_mode; |
bc7d2a3e | 127 | |
2fe5d6de MZ |
128 | if (!(mode & FMODE_WRITE)) |
129 | return; | |
130 | ||
5955102c | 131 | inode_lock(inode); |
b151d6b0 DK |
132 | if (atomic_read(&inode->i_writecount) == 1) { |
133 | if ((iint->version != inode->i_version) || | |
134 | (iint->flags & IMA_NEW_FILE)) { | |
135 | iint->flags &= ~(IMA_DONE_MASK | IMA_NEW_FILE); | |
a422638d | 136 | iint->measured_pcrs = 0; |
b151d6b0 DK |
137 | if (iint->flags & IMA_APPRAISE) |
138 | ima_update_xattr(iint, file); | |
139 | } | |
2fe5d6de | 140 | } |
5955102c | 141 | inode_unlock(inode); |
bc7d2a3e EP |
142 | } |
143 | ||
3323eec9 MZ |
144 | /** |
145 | * ima_file_free - called on __fput() | |
146 | * @file: pointer to file structure being freed | |
147 | * | |
890275b5 | 148 | * Flag files that changed, based on i_version |
3323eec9 MZ |
149 | */ |
150 | void ima_file_free(struct file *file) | |
151 | { | |
496ad9aa | 152 | struct inode *inode = file_inode(file); |
f381c272 | 153 | struct integrity_iint_cache *iint; |
3323eec9 | 154 | |
0f34a006 | 155 | if (!ima_policy_flag || !S_ISREG(inode->i_mode)) |
3323eec9 | 156 | return; |
196f5181 | 157 | |
f381c272 | 158 | iint = integrity_iint_find(inode); |
854fdd55 MZ |
159 | if (!iint) |
160 | return; | |
3323eec9 | 161 | |
854fdd55 | 162 | ima_check_last_writer(iint, inode, file); |
3323eec9 MZ |
163 | } |
164 | ||
cf222217 MZ |
165 | static int process_measurement(struct file *file, char *buf, loff_t size, |
166 | int mask, enum ima_hooks func, int opened) | |
3323eec9 | 167 | { |
496ad9aa | 168 | struct inode *inode = file_inode(file); |
f7a859ff | 169 | struct integrity_iint_cache *iint = NULL; |
209b43ca | 170 | struct ima_template_desc *template_desc; |
ea1046d4 | 171 | char *pathbuf = NULL; |
bc15ed66 | 172 | char filename[NAME_MAX]; |
ea1046d4 | 173 | const char *pathname = NULL; |
3a8a2ead | 174 | int rc = -ENOMEM, action, must_appraise; |
725de7fa | 175 | int pcr = CONFIG_IMA_MEASURE_PCR_IDX; |
1525b06d | 176 | struct evm_ima_xattr_data *xattr_value = NULL; |
d3634d0f | 177 | int xattr_len = 0; |
f7a859ff | 178 | bool violation_check; |
1525b06d | 179 | enum hash_algo hash_algo; |
3323eec9 | 180 | |
a756024e | 181 | if (!ima_policy_flag || !S_ISREG(inode->i_mode)) |
3323eec9 | 182 | return 0; |
bc7d2a3e | 183 | |
d79d72e0 MZ |
184 | /* Return an IMA_MEASURE, IMA_APPRAISE, IMA_AUDIT action |
185 | * bitmask based on the appraise/audit/measurement policy. | |
186 | * Included is the appraise submask. | |
187 | */ | |
725de7fa | 188 | action = ima_get_action(inode, mask, func, &pcr); |
4ad87a3d | 189 | violation_check = ((func == FILE_CHECK || func == MMAP_CHECK) && |
f7a859ff RS |
190 | (ima_policy_flag & IMA_MEASURE)); |
191 | if (!action && !violation_check) | |
2fe5d6de MZ |
192 | return 0; |
193 | ||
2fe5d6de | 194 | must_appraise = action & IMA_APPRAISE; |
bc7d2a3e | 195 | |
5a73fcfa | 196 | /* Is the appraise rule hook specific? */ |
3a8a2ead | 197 | if (action & IMA_FILE_APPRAISE) |
4ad87a3d | 198 | func = FILE_CHECK; |
5a73fcfa | 199 | |
5955102c | 200 | inode_lock(inode); |
2fe5d6de | 201 | |
f7a859ff RS |
202 | if (action) { |
203 | iint = integrity_inode_get(inode); | |
204 | if (!iint) | |
205 | goto out; | |
206 | } | |
207 | ||
208 | if (violation_check) { | |
1b68bdf9 RS |
209 | ima_rdwr_violation_check(file, iint, action & IMA_MEASURE, |
210 | &pathbuf, &pathname); | |
f7a859ff RS |
211 | if (!action) { |
212 | rc = 0; | |
213 | goto out_free; | |
214 | } | |
215 | } | |
bf2276d1 | 216 | |
2fe5d6de | 217 | /* Determine if already appraised/measured based on bitmask |
d79d72e0 MZ |
218 | * (IMA_MEASURE, IMA_MEASURED, IMA_XXXX_APPRAISE, IMA_XXXX_APPRAISED, |
219 | * IMA_AUDIT, IMA_AUDITED) | |
220 | */ | |
2fe5d6de | 221 | iint->flags |= action; |
0e5a247c | 222 | action &= IMA_DO_MASK; |
a422638d ER |
223 | action &= ~((iint->flags & (IMA_DONE_MASK ^ IMA_MEASURED)) >> 1); |
224 | ||
225 | /* If target pcr is already measured, unset IMA_MEASURE action */ | |
226 | if ((action & IMA_MEASURE) && (iint->measured_pcrs & (0x1 << pcr))) | |
227 | action ^= IMA_MEASURE; | |
2fe5d6de MZ |
228 | |
229 | /* Nothing to do, just return existing appraised status */ | |
230 | if (!action) { | |
d79d72e0 | 231 | if (must_appraise) |
4ad87a3d | 232 | rc = ima_get_cache_status(iint, func); |
a175b8bb | 233 | goto out_digsig; |
2fe5d6de | 234 | } |
3323eec9 | 235 | |
209b43ca | 236 | template_desc = ima_template_desc_current(); |
f68c05f4 DK |
237 | if ((action & IMA_APPRAISE_SUBMASK) || |
238 | strcmp(template_desc->name, IMA_TEMPLATE_IMA_NAME) != 0) | |
1525b06d | 239 | /* read 'security.ima' */ |
e71b9dff | 240 | xattr_len = ima_read_xattr(file_dentry(file), &xattr_value); |
d3634d0f | 241 | |
1525b06d DK |
242 | hash_algo = ima_get_hash_algo(xattr_value, xattr_len); |
243 | ||
cf222217 | 244 | rc = ima_collect_measurement(iint, file, buf, size, hash_algo); |
f3cc6b25 | 245 | if (rc != 0 && rc != -EBADF && rc != -EINVAL) |
a175b8bb | 246 | goto out_digsig; |
08e1b76a | 247 | |
bc15ed66 MZ |
248 | if (!pathbuf) /* ima_rdwr_violation possibly pre-fetched */ |
249 | pathname = ima_d_path(&file->f_path, &pathbuf, filename); | |
08e1b76a | 250 | |
2fe5d6de | 251 | if (action & IMA_MEASURE) |
bcbc9b0c | 252 | ima_store_measurement(iint, file, pathname, |
14b1da85 | 253 | xattr_value, xattr_len, pcr); |
f3cc6b25 | 254 | if (rc == 0 && (action & IMA_APPRAISE_SUBMASK)) |
4ad87a3d | 255 | rc = ima_appraise_measurement(func, iint, file, pathname, |
3034a146 | 256 | xattr_value, xattr_len, opened); |
e7c568e0 | 257 | if (action & IMA_AUDIT) |
ea1046d4 | 258 | ima_audit_measurement(iint, pathname); |
f7a859ff | 259 | |
f3cc6b25 MZ |
260 | if ((file->f_flags & O_DIRECT) && (iint->flags & IMA_PERMIT_DIRECTIO)) |
261 | rc = 0; | |
a175b8bb | 262 | out_digsig: |
05d1a717 MZ |
263 | if ((mask & MAY_WRITE) && (iint->flags & IMA_DIGSIG) && |
264 | !(iint->flags & IMA_NEW_FILE)) | |
a175b8bb | 265 | rc = -EACCES; |
f7a859ff RS |
266 | kfree(xattr_value); |
267 | out_free: | |
456f5fd3 DK |
268 | if (pathbuf) |
269 | __putname(pathbuf); | |
3323eec9 | 270 | out: |
5955102c | 271 | inode_unlock(inode); |
750943a3 DK |
272 | if ((rc && must_appraise) && (ima_appraise & IMA_APPRAISE_ENFORCE)) |
273 | return -EACCES; | |
274 | return 0; | |
3323eec9 MZ |
275 | } |
276 | ||
277 | /** | |
278 | * ima_file_mmap - based on policy, collect/store measurement. | |
279 | * @file: pointer to the file to be measured (May be NULL) | |
280 | * @prot: contains the protection that will be applied by the kernel. | |
281 | * | |
282 | * Measure files being mmapped executable based on the ima_must_measure() | |
283 | * policy decision. | |
284 | * | |
750943a3 DK |
285 | * On success return 0. On integrity appraisal error, assuming the file |
286 | * is in policy and IMA-appraisal is in enforcing mode, return -EACCES. | |
3323eec9 MZ |
287 | */ |
288 | int ima_file_mmap(struct file *file, unsigned long prot) | |
289 | { | |
750943a3 | 290 | if (file && (prot & PROT_EXEC)) |
cf222217 MZ |
291 | return process_measurement(file, NULL, 0, MAY_EXEC, |
292 | MMAP_CHECK, 0); | |
750943a3 | 293 | return 0; |
3323eec9 MZ |
294 | } |
295 | ||
296 | /** | |
297 | * ima_bprm_check - based on policy, collect/store measurement. | |
298 | * @bprm: contains the linux_binprm structure | |
299 | * | |
300 | * The OS protects against an executable file, already open for write, | |
301 | * from being executed in deny_write_access() and an executable file, | |
302 | * already open for execute, from being modified in get_write_access(). | |
303 | * So we can be certain that what we verify and measure here is actually | |
304 | * what is being executed. | |
305 | * | |
750943a3 DK |
306 | * On success return 0. On integrity appraisal error, assuming the file |
307 | * is in policy and IMA-appraisal is in enforcing mode, return -EACCES. | |
3323eec9 MZ |
308 | */ |
309 | int ima_bprm_check(struct linux_binprm *bprm) | |
310 | { | |
cf222217 MZ |
311 | return process_measurement(bprm->file, NULL, 0, MAY_EXEC, |
312 | BPRM_CHECK, 0); | |
3323eec9 MZ |
313 | } |
314 | ||
8eb988c7 MZ |
315 | /** |
316 | * ima_path_check - based on policy, collect/store measurement. | |
317 | * @file: pointer to the file to be measured | |
20f482ab | 318 | * @mask: contains MAY_READ, MAY_WRITE, MAY_EXEC or MAY_APPEND |
8eb988c7 MZ |
319 | * |
320 | * Measure files based on the ima_must_measure() policy decision. | |
321 | * | |
750943a3 DK |
322 | * On success return 0. On integrity appraisal error, assuming the file |
323 | * is in policy and IMA-appraisal is in enforcing mode, return -EACCES. | |
8eb988c7 | 324 | */ |
3034a146 | 325 | int ima_file_check(struct file *file, int mask, int opened) |
8eb988c7 | 326 | { |
cf222217 | 327 | return process_measurement(file, NULL, 0, |
20f482ab LZ |
328 | mask & (MAY_READ | MAY_WRITE | MAY_EXEC | |
329 | MAY_APPEND), FILE_CHECK, opened); | |
8eb988c7 | 330 | } |
9bbb6cad | 331 | EXPORT_SYMBOL_GPL(ima_file_check); |
8eb988c7 | 332 | |
05d1a717 MZ |
333 | /** |
334 | * ima_post_path_mknod - mark as a new inode | |
335 | * @dentry: newly created dentry | |
336 | * | |
337 | * Mark files created via the mknodat syscall as new, so that the | |
338 | * file data can be written later. | |
339 | */ | |
340 | void ima_post_path_mknod(struct dentry *dentry) | |
341 | { | |
342 | struct integrity_iint_cache *iint; | |
343 | struct inode *inode = dentry->d_inode; | |
344 | int must_appraise; | |
345 | ||
346 | must_appraise = ima_must_appraise(inode, MAY_ACCESS, FILE_CHECK); | |
347 | if (!must_appraise) | |
348 | return; | |
349 | ||
350 | iint = integrity_inode_get(inode); | |
351 | if (iint) | |
352 | iint->flags |= IMA_NEW_FILE; | |
353 | } | |
354 | ||
39eeb4fb MZ |
355 | /** |
356 | * ima_read_file - pre-measure/appraise hook decision based on policy | |
357 | * @file: pointer to the file to be measured/appraised/audit | |
358 | * @read_id: caller identifier | |
359 | * | |
360 | * Permit reading a file based on policy. The policy rules are written | |
361 | * in terms of the policy identifier. Appraising the integrity of | |
362 | * a file requires a file descriptor. | |
363 | * | |
364 | * For permission return 0, otherwise return -EACCES. | |
365 | */ | |
366 | int ima_read_file(struct file *file, enum kernel_read_file_id read_id) | |
367 | { | |
7c9bc098 BM |
368 | bool sig_enforce = is_module_sig_enforced(); |
369 | ||
a1db7420 | 370 | if (!file && read_id == READING_MODULE) { |
7c9bc098 | 371 | if (!sig_enforce && (ima_appraise & IMA_APPRAISE_MODULES) && |
a1db7420 MZ |
372 | (ima_appraise & IMA_APPRAISE_ENFORCE)) |
373 | return -EACCES; /* INTEGRITY_UNKNOWN */ | |
a1db7420 MZ |
374 | return 0; /* We rely on module signature checking */ |
375 | } | |
39eeb4fb MZ |
376 | return 0; |
377 | } | |
378 | ||
d9ddf077 MZ |
379 | static int read_idmap[READING_MAX_ID] = { |
380 | [READING_FIRMWARE] = FIRMWARE_CHECK, | |
88d941dc | 381 | [READING_FIRMWARE_PREALLOC_BUFFER] = FIRMWARE_CHECK, |
d9ddf077 MZ |
382 | [READING_MODULE] = MODULE_CHECK, |
383 | [READING_KEXEC_IMAGE] = KEXEC_KERNEL_CHECK, | |
384 | [READING_KEXEC_INITRAMFS] = KEXEC_INITRAMFS_CHECK, | |
19f8a847 | 385 | [READING_POLICY] = POLICY_CHECK |
d9ddf077 MZ |
386 | }; |
387 | ||
cf222217 MZ |
388 | /** |
389 | * ima_post_read_file - in memory collect/appraise/audit measurement | |
390 | * @file: pointer to the file to be measured/appraised/audit | |
391 | * @buf: pointer to in memory file contents | |
392 | * @size: size of in memory file contents | |
393 | * @read_id: caller identifier | |
394 | * | |
395 | * Measure/appraise/audit in memory file based on policy. Policy rules | |
396 | * are written in terms of a policy identifier. | |
397 | * | |
398 | * On success return 0. On integrity appraisal error, assuming the file | |
399 | * is in policy and IMA-appraisal is in enforcing mode, return -EACCES. | |
400 | */ | |
401 | int ima_post_read_file(struct file *file, void *buf, loff_t size, | |
402 | enum kernel_read_file_id read_id) | |
403 | { | |
d9ddf077 | 404 | enum ima_hooks func; |
cf222217 | 405 | |
e40ba6d5 MZ |
406 | if (!file && read_id == READING_FIRMWARE) { |
407 | if ((ima_appraise & IMA_APPRAISE_FIRMWARE) && | |
408 | (ima_appraise & IMA_APPRAISE_ENFORCE)) | |
409 | return -EACCES; /* INTEGRITY_UNKNOWN */ | |
410 | return 0; | |
411 | } | |
412 | ||
a1db7420 MZ |
413 | if (!file && read_id == READING_MODULE) /* MODULE_SIG_FORCE enabled */ |
414 | return 0; | |
415 | ||
a7d3d039 CH |
416 | /* permit signed certs */ |
417 | if (!file && read_id == READING_X509_CERTIFICATE) | |
418 | return 0; | |
419 | ||
cf222217 MZ |
420 | if (!file || !buf || size == 0) { /* should never happen */ |
421 | if (ima_appraise & IMA_APPRAISE_ENFORCE) | |
422 | return -EACCES; | |
423 | return 0; | |
424 | } | |
425 | ||
d9ddf077 | 426 | func = read_idmap[read_id] ?: FILE_CHECK; |
cf222217 | 427 | return process_measurement(file, buf, size, MAY_READ, func, 0); |
5a9196d7 MZ |
428 | } |
429 | ||
3323eec9 MZ |
430 | static int __init init_ima(void) |
431 | { | |
432 | int error; | |
433 | ||
3f23d624 | 434 | ima_init_template_list(); |
e7a2ad7e | 435 | hash_setup(CONFIG_IMA_DEFAULT_HASH); |
3323eec9 | 436 | error = ima_init(); |
8a048adc PV |
437 | |
438 | if (error && strcmp(hash_algo_name[ima_hash_algo], | |
439 | CONFIG_IMA_DEFAULT_HASH) != 0) { | |
440 | pr_info("Allocating %s failed, going to use default hash algorithm %s\n", | |
441 | hash_algo_name[ima_hash_algo], CONFIG_IMA_DEFAULT_HASH); | |
442 | hash_setup_done = 0; | |
443 | hash_setup(CONFIG_IMA_DEFAULT_HASH); | |
444 | error = ima_init(); | |
445 | } | |
446 | ||
a756024e | 447 | if (!error) { |
31b70f66 | 448 | ima_initialized = 1; |
a756024e RS |
449 | ima_update_policy_flag(); |
450 | } | |
3323eec9 MZ |
451 | return error; |
452 | } | |
453 | ||
454 | late_initcall(init_ima); /* Start IMA after the TPM is available */ | |
455 | ||
456 | MODULE_DESCRIPTION("Integrity Measurement Architecture"); | |
457 | MODULE_LICENSE("GPL"); |