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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 MZ |
18 | */ |
19 | #include <linux/module.h> | |
20 | #include <linux/file.h> | |
21 | #include <linux/binfmts.h> | |
22 | #include <linux/mount.h> | |
23 | #include <linux/mman.h> | |
5a0e3ad6 | 24 | #include <linux/slab.h> |
2fe5d6de | 25 | #include <linux/xattr.h> |
d5813a57 | 26 | #include <linux/ima.h> |
3323eec9 MZ |
27 | |
28 | #include "ima.h" | |
29 | ||
30 | int ima_initialized; | |
31 | ||
2fe5d6de MZ |
32 | #ifdef CONFIG_IMA_APPRAISE |
33 | int ima_appraise = IMA_APPRAISE_ENFORCE; | |
34 | #else | |
35 | int ima_appraise; | |
36 | #endif | |
37 | ||
c7c8bb23 | 38 | int ima_hash_algo = HASH_ALGO_SHA1; |
e7a2ad7e | 39 | static int hash_setup_done; |
c7c8bb23 | 40 | |
3323eec9 MZ |
41 | static int __init hash_setup(char *str) |
42 | { | |
e7a2ad7e MZ |
43 | struct ima_template_desc *template_desc = ima_template_desc_current(); |
44 | int i; | |
45 | ||
46 | if (hash_setup_done) | |
47 | return 1; | |
48 | ||
49 | if (strcmp(template_desc->name, IMA_TEMPLATE_IMA_NAME) == 0) { | |
50 | if (strncmp(str, "sha1", 4) == 0) | |
51 | ima_hash_algo = HASH_ALGO_SHA1; | |
52 | else if (strncmp(str, "md5", 3) == 0) | |
53 | ima_hash_algo = HASH_ALGO_MD5; | |
54 | goto out; | |
55 | } | |
56 | ||
57 | for (i = 0; i < HASH_ALGO__LAST; i++) { | |
58 | if (strcmp(str, hash_algo_name[i]) == 0) { | |
59 | ima_hash_algo = i; | |
60 | break; | |
61 | } | |
62 | } | |
63 | out: | |
64 | hash_setup_done = 1; | |
3323eec9 MZ |
65 | return 1; |
66 | } | |
67 | __setup("ima_hash=", hash_setup); | |
68 | ||
8eb988c7 | 69 | /* |
890275b5 | 70 | * ima_rdwr_violation_check |
8eb988c7 | 71 | * |
890275b5 | 72 | * Only invalidate the PCR for measured files: |
2bb930ab | 73 | * - Opening a file for write when already open for read, |
8eb988c7 MZ |
74 | * results in a time of measure, time of use (ToMToU) error. |
75 | * - Opening a file for read when already open for write, | |
2bb930ab | 76 | * could result in a file measurement error. |
8eb988c7 MZ |
77 | * |
78 | */ | |
f7a859ff RS |
79 | static void ima_rdwr_violation_check(struct file *file, |
80 | struct integrity_iint_cache *iint, | |
1b68bdf9 | 81 | int must_measure, |
f7a859ff RS |
82 | char **pathbuf, |
83 | const char **pathname) | |
8eb988c7 | 84 | { |
c77cecee | 85 | struct inode *inode = file_inode(file); |
bc15ed66 | 86 | char filename[NAME_MAX]; |
8eb988c7 | 87 | fmode_t mode = file->f_mode; |
ad16ad00 | 88 | bool send_tomtou = false, send_writers = false; |
a178d202 | 89 | |
8eb988c7 | 90 | if (mode & FMODE_WRITE) { |
14503eb9 | 91 | if (atomic_read(&inode->i_readcount) && IS_IMA(inode)) { |
f7a859ff RS |
92 | if (!iint) |
93 | iint = integrity_iint_find(inode); | |
14503eb9 DK |
94 | /* IMA_MEASURE is set from reader side */ |
95 | if (iint && (iint->flags & IMA_MEASURE)) | |
96 | send_tomtou = true; | |
97 | } | |
b882fae2 | 98 | } else { |
1b68bdf9 | 99 | if ((atomic_read(&inode->i_writecount) > 0) && must_measure) |
b882fae2 | 100 | send_writers = true; |
8eb988c7 | 101 | } |
ad16ad00 | 102 | |
08e1b76a MZ |
103 | if (!send_tomtou && !send_writers) |
104 | return; | |
105 | ||
bc15ed66 | 106 | *pathname = ima_d_path(&file->f_path, pathbuf, filename); |
ea1046d4 | 107 | |
ad16ad00 | 108 | if (send_tomtou) |
8d94eb9b RS |
109 | ima_add_violation(file, *pathname, iint, |
110 | "invalid_pcr", "ToMToU"); | |
ad16ad00 | 111 | if (send_writers) |
8d94eb9b | 112 | ima_add_violation(file, *pathname, iint, |
08e1b76a | 113 | "invalid_pcr", "open_writers"); |
8eb988c7 MZ |
114 | } |
115 | ||
f381c272 | 116 | static void ima_check_last_writer(struct integrity_iint_cache *iint, |
2fe5d6de | 117 | struct inode *inode, struct file *file) |
bc7d2a3e | 118 | { |
4b2a2c67 | 119 | fmode_t mode = file->f_mode; |
bc7d2a3e | 120 | |
2fe5d6de MZ |
121 | if (!(mode & FMODE_WRITE)) |
122 | return; | |
123 | ||
5955102c | 124 | inode_lock(inode); |
b151d6b0 DK |
125 | if (atomic_read(&inode->i_writecount) == 1) { |
126 | if ((iint->version != inode->i_version) || | |
127 | (iint->flags & IMA_NEW_FILE)) { | |
128 | iint->flags &= ~(IMA_DONE_MASK | IMA_NEW_FILE); | |
a422638d | 129 | iint->measured_pcrs = 0; |
b151d6b0 DK |
130 | if (iint->flags & IMA_APPRAISE) |
131 | ima_update_xattr(iint, file); | |
132 | } | |
2fe5d6de | 133 | } |
5955102c | 134 | inode_unlock(inode); |
bc7d2a3e EP |
135 | } |
136 | ||
3323eec9 MZ |
137 | /** |
138 | * ima_file_free - called on __fput() | |
139 | * @file: pointer to file structure being freed | |
140 | * | |
890275b5 | 141 | * Flag files that changed, based on i_version |
3323eec9 MZ |
142 | */ |
143 | void ima_file_free(struct file *file) | |
144 | { | |
496ad9aa | 145 | struct inode *inode = file_inode(file); |
f381c272 | 146 | struct integrity_iint_cache *iint; |
3323eec9 | 147 | |
0f34a006 | 148 | if (!ima_policy_flag || !S_ISREG(inode->i_mode)) |
3323eec9 | 149 | return; |
196f5181 | 150 | |
f381c272 | 151 | iint = integrity_iint_find(inode); |
854fdd55 MZ |
152 | if (!iint) |
153 | return; | |
3323eec9 | 154 | |
854fdd55 | 155 | ima_check_last_writer(iint, inode, file); |
3323eec9 MZ |
156 | } |
157 | ||
cf222217 MZ |
158 | static int process_measurement(struct file *file, char *buf, loff_t size, |
159 | int mask, enum ima_hooks func, int opened) | |
3323eec9 | 160 | { |
496ad9aa | 161 | struct inode *inode = file_inode(file); |
f7a859ff | 162 | struct integrity_iint_cache *iint = NULL; |
209b43ca | 163 | struct ima_template_desc *template_desc; |
ea1046d4 | 164 | char *pathbuf = NULL; |
bc15ed66 | 165 | char filename[NAME_MAX]; |
ea1046d4 | 166 | const char *pathname = NULL; |
3a8a2ead | 167 | int rc = -ENOMEM, action, must_appraise; |
725de7fa | 168 | int pcr = CONFIG_IMA_MEASURE_PCR_IDX; |
1525b06d | 169 | struct evm_ima_xattr_data *xattr_value = NULL; |
d3634d0f | 170 | int xattr_len = 0; |
f7a859ff | 171 | bool violation_check; |
1525b06d | 172 | enum hash_algo hash_algo; |
3323eec9 | 173 | |
a756024e | 174 | if (!ima_policy_flag || !S_ISREG(inode->i_mode)) |
3323eec9 | 175 | return 0; |
bc7d2a3e | 176 | |
d79d72e0 MZ |
177 | /* Return an IMA_MEASURE, IMA_APPRAISE, IMA_AUDIT action |
178 | * bitmask based on the appraise/audit/measurement policy. | |
179 | * Included is the appraise submask. | |
180 | */ | |
725de7fa | 181 | action = ima_get_action(inode, mask, func, &pcr); |
4ad87a3d | 182 | violation_check = ((func == FILE_CHECK || func == MMAP_CHECK) && |
f7a859ff RS |
183 | (ima_policy_flag & IMA_MEASURE)); |
184 | if (!action && !violation_check) | |
2fe5d6de MZ |
185 | return 0; |
186 | ||
2fe5d6de | 187 | must_appraise = action & IMA_APPRAISE; |
bc7d2a3e | 188 | |
5a73fcfa | 189 | /* Is the appraise rule hook specific? */ |
3a8a2ead | 190 | if (action & IMA_FILE_APPRAISE) |
4ad87a3d | 191 | func = FILE_CHECK; |
5a73fcfa | 192 | |
5955102c | 193 | inode_lock(inode); |
2fe5d6de | 194 | |
f7a859ff RS |
195 | if (action) { |
196 | iint = integrity_inode_get(inode); | |
197 | if (!iint) | |
198 | goto out; | |
199 | } | |
200 | ||
201 | if (violation_check) { | |
1b68bdf9 RS |
202 | ima_rdwr_violation_check(file, iint, action & IMA_MEASURE, |
203 | &pathbuf, &pathname); | |
f7a859ff RS |
204 | if (!action) { |
205 | rc = 0; | |
206 | goto out_free; | |
207 | } | |
208 | } | |
bf2276d1 | 209 | |
2fe5d6de | 210 | /* Determine if already appraised/measured based on bitmask |
d79d72e0 MZ |
211 | * (IMA_MEASURE, IMA_MEASURED, IMA_XXXX_APPRAISE, IMA_XXXX_APPRAISED, |
212 | * IMA_AUDIT, IMA_AUDITED) | |
213 | */ | |
2fe5d6de | 214 | iint->flags |= action; |
0e5a247c | 215 | action &= IMA_DO_MASK; |
a422638d ER |
216 | action &= ~((iint->flags & (IMA_DONE_MASK ^ IMA_MEASURED)) >> 1); |
217 | ||
218 | /* If target pcr is already measured, unset IMA_MEASURE action */ | |
219 | if ((action & IMA_MEASURE) && (iint->measured_pcrs & (0x1 << pcr))) | |
220 | action ^= IMA_MEASURE; | |
2fe5d6de MZ |
221 | |
222 | /* Nothing to do, just return existing appraised status */ | |
223 | if (!action) { | |
d79d72e0 | 224 | if (must_appraise) |
4ad87a3d | 225 | rc = ima_get_cache_status(iint, func); |
a175b8bb | 226 | goto out_digsig; |
2fe5d6de | 227 | } |
3323eec9 | 228 | |
209b43ca | 229 | template_desc = ima_template_desc_current(); |
f68c05f4 DK |
230 | if ((action & IMA_APPRAISE_SUBMASK) || |
231 | strcmp(template_desc->name, IMA_TEMPLATE_IMA_NAME) != 0) | |
1525b06d | 232 | /* read 'security.ima' */ |
e71b9dff | 233 | xattr_len = ima_read_xattr(file_dentry(file), &xattr_value); |
d3634d0f | 234 | |
1525b06d DK |
235 | hash_algo = ima_get_hash_algo(xattr_value, xattr_len); |
236 | ||
cf222217 | 237 | rc = ima_collect_measurement(iint, file, buf, size, hash_algo); |
f9b2a735 MZ |
238 | if (rc != 0) { |
239 | if (file->f_flags & O_DIRECT) | |
240 | rc = (iint->flags & IMA_PERMIT_DIRECTIO) ? 0 : -EACCES; | |
a175b8bb | 241 | goto out_digsig; |
f9b2a735 | 242 | } |
08e1b76a | 243 | |
bc15ed66 MZ |
244 | if (!pathbuf) /* ima_rdwr_violation possibly pre-fetched */ |
245 | pathname = ima_d_path(&file->f_path, &pathbuf, filename); | |
08e1b76a | 246 | |
2fe5d6de | 247 | if (action & IMA_MEASURE) |
bcbc9b0c | 248 | ima_store_measurement(iint, file, pathname, |
14b1da85 | 249 | xattr_value, xattr_len, pcr); |
d79d72e0 | 250 | if (action & IMA_APPRAISE_SUBMASK) |
4ad87a3d | 251 | rc = ima_appraise_measurement(func, iint, file, pathname, |
3034a146 | 252 | xattr_value, xattr_len, opened); |
e7c568e0 | 253 | if (action & IMA_AUDIT) |
ea1046d4 | 254 | ima_audit_measurement(iint, pathname); |
f7a859ff | 255 | |
a175b8bb | 256 | out_digsig: |
05d1a717 MZ |
257 | if ((mask & MAY_WRITE) && (iint->flags & IMA_DIGSIG) && |
258 | !(iint->flags & IMA_NEW_FILE)) | |
a175b8bb | 259 | rc = -EACCES; |
f7a859ff RS |
260 | kfree(xattr_value); |
261 | out_free: | |
456f5fd3 DK |
262 | if (pathbuf) |
263 | __putname(pathbuf); | |
3323eec9 | 264 | out: |
5955102c | 265 | inode_unlock(inode); |
750943a3 DK |
266 | if ((rc && must_appraise) && (ima_appraise & IMA_APPRAISE_ENFORCE)) |
267 | return -EACCES; | |
268 | return 0; | |
3323eec9 MZ |
269 | } |
270 | ||
271 | /** | |
272 | * ima_file_mmap - based on policy, collect/store measurement. | |
273 | * @file: pointer to the file to be measured (May be NULL) | |
274 | * @prot: contains the protection that will be applied by the kernel. | |
275 | * | |
276 | * Measure files being mmapped executable based on the ima_must_measure() | |
277 | * policy decision. | |
278 | * | |
750943a3 DK |
279 | * On success return 0. On integrity appraisal error, assuming the file |
280 | * is in policy and IMA-appraisal is in enforcing mode, return -EACCES. | |
3323eec9 MZ |
281 | */ |
282 | int ima_file_mmap(struct file *file, unsigned long prot) | |
283 | { | |
750943a3 | 284 | if (file && (prot & PROT_EXEC)) |
cf222217 MZ |
285 | return process_measurement(file, NULL, 0, MAY_EXEC, |
286 | MMAP_CHECK, 0); | |
750943a3 | 287 | return 0; |
3323eec9 MZ |
288 | } |
289 | ||
290 | /** | |
291 | * ima_bprm_check - based on policy, collect/store measurement. | |
292 | * @bprm: contains the linux_binprm structure | |
293 | * | |
294 | * The OS protects against an executable file, already open for write, | |
295 | * from being executed in deny_write_access() and an executable file, | |
296 | * already open for execute, from being modified in get_write_access(). | |
297 | * So we can be certain that what we verify and measure here is actually | |
298 | * what is being executed. | |
299 | * | |
750943a3 DK |
300 | * On success return 0. On integrity appraisal error, assuming the file |
301 | * is in policy and IMA-appraisal is in enforcing mode, return -EACCES. | |
3323eec9 MZ |
302 | */ |
303 | int ima_bprm_check(struct linux_binprm *bprm) | |
304 | { | |
cf222217 MZ |
305 | return process_measurement(bprm->file, NULL, 0, MAY_EXEC, |
306 | BPRM_CHECK, 0); | |
3323eec9 MZ |
307 | } |
308 | ||
8eb988c7 MZ |
309 | /** |
310 | * ima_path_check - based on policy, collect/store measurement. | |
311 | * @file: pointer to the file to be measured | |
20f482ab | 312 | * @mask: contains MAY_READ, MAY_WRITE, MAY_EXEC or MAY_APPEND |
8eb988c7 MZ |
313 | * |
314 | * Measure files based on the ima_must_measure() policy decision. | |
315 | * | |
750943a3 DK |
316 | * On success return 0. On integrity appraisal error, assuming the file |
317 | * is in policy and IMA-appraisal is in enforcing mode, return -EACCES. | |
8eb988c7 | 318 | */ |
3034a146 | 319 | int ima_file_check(struct file *file, int mask, int opened) |
8eb988c7 | 320 | { |
cf222217 | 321 | return process_measurement(file, NULL, 0, |
20f482ab LZ |
322 | mask & (MAY_READ | MAY_WRITE | MAY_EXEC | |
323 | MAY_APPEND), FILE_CHECK, opened); | |
8eb988c7 | 324 | } |
9bbb6cad | 325 | EXPORT_SYMBOL_GPL(ima_file_check); |
8eb988c7 | 326 | |
05d1a717 MZ |
327 | /** |
328 | * ima_post_path_mknod - mark as a new inode | |
329 | * @dentry: newly created dentry | |
330 | * | |
331 | * Mark files created via the mknodat syscall as new, so that the | |
332 | * file data can be written later. | |
333 | */ | |
334 | void ima_post_path_mknod(struct dentry *dentry) | |
335 | { | |
336 | struct integrity_iint_cache *iint; | |
337 | struct inode *inode = dentry->d_inode; | |
338 | int must_appraise; | |
339 | ||
340 | must_appraise = ima_must_appraise(inode, MAY_ACCESS, FILE_CHECK); | |
341 | if (!must_appraise) | |
342 | return; | |
343 | ||
344 | iint = integrity_inode_get(inode); | |
345 | if (iint) | |
346 | iint->flags |= IMA_NEW_FILE; | |
347 | } | |
348 | ||
39eeb4fb MZ |
349 | /** |
350 | * ima_read_file - pre-measure/appraise hook decision based on policy | |
351 | * @file: pointer to the file to be measured/appraised/audit | |
352 | * @read_id: caller identifier | |
353 | * | |
354 | * Permit reading a file based on policy. The policy rules are written | |
355 | * in terms of the policy identifier. Appraising the integrity of | |
356 | * a file requires a file descriptor. | |
357 | * | |
358 | * For permission return 0, otherwise return -EACCES. | |
359 | */ | |
360 | int ima_read_file(struct file *file, enum kernel_read_file_id read_id) | |
361 | { | |
a1db7420 MZ |
362 | if (!file && read_id == READING_MODULE) { |
363 | #ifndef CONFIG_MODULE_SIG_FORCE | |
364 | if ((ima_appraise & IMA_APPRAISE_MODULES) && | |
365 | (ima_appraise & IMA_APPRAISE_ENFORCE)) | |
366 | return -EACCES; /* INTEGRITY_UNKNOWN */ | |
367 | #endif | |
368 | return 0; /* We rely on module signature checking */ | |
369 | } | |
39eeb4fb MZ |
370 | return 0; |
371 | } | |
372 | ||
d9ddf077 MZ |
373 | static int read_idmap[READING_MAX_ID] = { |
374 | [READING_FIRMWARE] = FIRMWARE_CHECK, | |
375 | [READING_MODULE] = MODULE_CHECK, | |
376 | [READING_KEXEC_IMAGE] = KEXEC_KERNEL_CHECK, | |
377 | [READING_KEXEC_INITRAMFS] = KEXEC_INITRAMFS_CHECK, | |
19f8a847 | 378 | [READING_POLICY] = POLICY_CHECK |
d9ddf077 MZ |
379 | }; |
380 | ||
cf222217 MZ |
381 | /** |
382 | * ima_post_read_file - in memory collect/appraise/audit measurement | |
383 | * @file: pointer to the file to be measured/appraised/audit | |
384 | * @buf: pointer to in memory file contents | |
385 | * @size: size of in memory file contents | |
386 | * @read_id: caller identifier | |
387 | * | |
388 | * Measure/appraise/audit in memory file based on policy. Policy rules | |
389 | * are written in terms of a policy identifier. | |
390 | * | |
391 | * On success return 0. On integrity appraisal error, assuming the file | |
392 | * is in policy and IMA-appraisal is in enforcing mode, return -EACCES. | |
393 | */ | |
394 | int ima_post_read_file(struct file *file, void *buf, loff_t size, | |
395 | enum kernel_read_file_id read_id) | |
396 | { | |
d9ddf077 | 397 | enum ima_hooks func; |
cf222217 | 398 | |
e40ba6d5 MZ |
399 | if (!file && read_id == READING_FIRMWARE) { |
400 | if ((ima_appraise & IMA_APPRAISE_FIRMWARE) && | |
401 | (ima_appraise & IMA_APPRAISE_ENFORCE)) | |
402 | return -EACCES; /* INTEGRITY_UNKNOWN */ | |
403 | return 0; | |
404 | } | |
405 | ||
a1db7420 MZ |
406 | if (!file && read_id == READING_MODULE) /* MODULE_SIG_FORCE enabled */ |
407 | return 0; | |
408 | ||
cf222217 MZ |
409 | if (!file || !buf || size == 0) { /* should never happen */ |
410 | if (ima_appraise & IMA_APPRAISE_ENFORCE) | |
411 | return -EACCES; | |
412 | return 0; | |
413 | } | |
414 | ||
d9ddf077 | 415 | func = read_idmap[read_id] ?: FILE_CHECK; |
cf222217 | 416 | return process_measurement(file, buf, size, MAY_READ, func, 0); |
5a9196d7 MZ |
417 | } |
418 | ||
3323eec9 MZ |
419 | static int __init init_ima(void) |
420 | { | |
421 | int error; | |
422 | ||
3f23d624 | 423 | ima_init_template_list(); |
e7a2ad7e | 424 | hash_setup(CONFIG_IMA_DEFAULT_HASH); |
3323eec9 | 425 | error = ima_init(); |
a756024e | 426 | if (!error) { |
31b70f66 | 427 | ima_initialized = 1; |
a756024e RS |
428 | ima_update_policy_flag(); |
429 | } | |
3323eec9 MZ |
430 | return error; |
431 | } | |
432 | ||
433 | late_initcall(init_ima); /* Start IMA after the TPM is available */ | |
434 | ||
435 | MODULE_DESCRIPTION("Integrity Measurement Architecture"); | |
436 | MODULE_LICENSE("GPL"); |