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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); |
8eb988c7 | 86 | fmode_t mode = file->f_mode; |
ad16ad00 | 87 | bool send_tomtou = false, send_writers = false; |
a178d202 | 88 | |
8eb988c7 | 89 | if (mode & FMODE_WRITE) { |
14503eb9 | 90 | if (atomic_read(&inode->i_readcount) && IS_IMA(inode)) { |
f7a859ff RS |
91 | if (!iint) |
92 | iint = integrity_iint_find(inode); | |
14503eb9 DK |
93 | /* IMA_MEASURE is set from reader side */ |
94 | if (iint && (iint->flags & IMA_MEASURE)) | |
95 | send_tomtou = true; | |
96 | } | |
b882fae2 | 97 | } else { |
1b68bdf9 | 98 | if ((atomic_read(&inode->i_writecount) > 0) && must_measure) |
b882fae2 | 99 | send_writers = true; |
8eb988c7 | 100 | } |
ad16ad00 | 101 | |
08e1b76a MZ |
102 | if (!send_tomtou && !send_writers) |
103 | return; | |
104 | ||
f7a859ff | 105 | *pathname = ima_d_path(&file->f_path, pathbuf); |
ea1046d4 | 106 | |
ad16ad00 | 107 | if (send_tomtou) |
8d94eb9b RS |
108 | ima_add_violation(file, *pathname, iint, |
109 | "invalid_pcr", "ToMToU"); | |
ad16ad00 | 110 | if (send_writers) |
8d94eb9b | 111 | ima_add_violation(file, *pathname, iint, |
08e1b76a | 112 | "invalid_pcr", "open_writers"); |
8eb988c7 MZ |
113 | } |
114 | ||
f381c272 | 115 | static void ima_check_last_writer(struct integrity_iint_cache *iint, |
2fe5d6de | 116 | struct inode *inode, struct file *file) |
bc7d2a3e | 117 | { |
4b2a2c67 | 118 | fmode_t mode = file->f_mode; |
bc7d2a3e | 119 | |
2fe5d6de MZ |
120 | if (!(mode & FMODE_WRITE)) |
121 | return; | |
122 | ||
5955102c | 123 | inode_lock(inode); |
b151d6b0 DK |
124 | if (atomic_read(&inode->i_writecount) == 1) { |
125 | if ((iint->version != inode->i_version) || | |
126 | (iint->flags & IMA_NEW_FILE)) { | |
127 | iint->flags &= ~(IMA_DONE_MASK | IMA_NEW_FILE); | |
128 | if (iint->flags & IMA_APPRAISE) | |
129 | ima_update_xattr(iint, file); | |
130 | } | |
2fe5d6de | 131 | } |
5955102c | 132 | inode_unlock(inode); |
bc7d2a3e EP |
133 | } |
134 | ||
3323eec9 MZ |
135 | /** |
136 | * ima_file_free - called on __fput() | |
137 | * @file: pointer to file structure being freed | |
138 | * | |
890275b5 | 139 | * Flag files that changed, based on i_version |
3323eec9 MZ |
140 | */ |
141 | void ima_file_free(struct file *file) | |
142 | { | |
496ad9aa | 143 | struct inode *inode = file_inode(file); |
f381c272 | 144 | struct integrity_iint_cache *iint; |
3323eec9 | 145 | |
0f34a006 | 146 | if (!ima_policy_flag || !S_ISREG(inode->i_mode)) |
3323eec9 | 147 | return; |
196f5181 | 148 | |
f381c272 | 149 | iint = integrity_iint_find(inode); |
854fdd55 MZ |
150 | if (!iint) |
151 | return; | |
3323eec9 | 152 | |
854fdd55 | 153 | ima_check_last_writer(iint, inode, file); |
3323eec9 MZ |
154 | } |
155 | ||
cf222217 MZ |
156 | static int process_measurement(struct file *file, char *buf, loff_t size, |
157 | int mask, enum ima_hooks func, int opened) | |
3323eec9 | 158 | { |
496ad9aa | 159 | struct inode *inode = file_inode(file); |
f7a859ff | 160 | struct integrity_iint_cache *iint = NULL; |
209b43ca | 161 | struct ima_template_desc *template_desc; |
ea1046d4 DK |
162 | char *pathbuf = NULL; |
163 | const char *pathname = NULL; | |
3a8a2ead | 164 | int rc = -ENOMEM, action, must_appraise; |
1525b06d | 165 | struct evm_ima_xattr_data *xattr_value = NULL; |
d3634d0f | 166 | int xattr_len = 0; |
f7a859ff | 167 | bool violation_check; |
1525b06d | 168 | enum hash_algo hash_algo; |
3323eec9 | 169 | |
a756024e | 170 | if (!ima_policy_flag || !S_ISREG(inode->i_mode)) |
3323eec9 | 171 | return 0; |
bc7d2a3e | 172 | |
d79d72e0 MZ |
173 | /* Return an IMA_MEASURE, IMA_APPRAISE, IMA_AUDIT action |
174 | * bitmask based on the appraise/audit/measurement policy. | |
175 | * Included is the appraise submask. | |
176 | */ | |
4ad87a3d MZ |
177 | action = ima_get_action(inode, mask, func); |
178 | violation_check = ((func == FILE_CHECK || func == MMAP_CHECK) && | |
f7a859ff RS |
179 | (ima_policy_flag & IMA_MEASURE)); |
180 | if (!action && !violation_check) | |
2fe5d6de MZ |
181 | return 0; |
182 | ||
2fe5d6de | 183 | must_appraise = action & IMA_APPRAISE; |
bc7d2a3e | 184 | |
5a73fcfa | 185 | /* Is the appraise rule hook specific? */ |
3a8a2ead | 186 | if (action & IMA_FILE_APPRAISE) |
4ad87a3d | 187 | func = FILE_CHECK; |
5a73fcfa | 188 | |
5955102c | 189 | inode_lock(inode); |
2fe5d6de | 190 | |
f7a859ff RS |
191 | if (action) { |
192 | iint = integrity_inode_get(inode); | |
193 | if (!iint) | |
194 | goto out; | |
195 | } | |
196 | ||
197 | if (violation_check) { | |
1b68bdf9 RS |
198 | ima_rdwr_violation_check(file, iint, action & IMA_MEASURE, |
199 | &pathbuf, &pathname); | |
f7a859ff RS |
200 | if (!action) { |
201 | rc = 0; | |
202 | goto out_free; | |
203 | } | |
204 | } | |
bf2276d1 | 205 | |
2fe5d6de | 206 | /* Determine if already appraised/measured based on bitmask |
d79d72e0 MZ |
207 | * (IMA_MEASURE, IMA_MEASURED, IMA_XXXX_APPRAISE, IMA_XXXX_APPRAISED, |
208 | * IMA_AUDIT, IMA_AUDITED) | |
209 | */ | |
2fe5d6de | 210 | iint->flags |= action; |
0e5a247c | 211 | action &= IMA_DO_MASK; |
45e2472e | 212 | action &= ~((iint->flags & IMA_DONE_MASK) >> 1); |
2fe5d6de MZ |
213 | |
214 | /* Nothing to do, just return existing appraised status */ | |
215 | if (!action) { | |
d79d72e0 | 216 | if (must_appraise) |
4ad87a3d | 217 | rc = ima_get_cache_status(iint, func); |
a175b8bb | 218 | goto out_digsig; |
2fe5d6de | 219 | } |
3323eec9 | 220 | |
209b43ca | 221 | template_desc = ima_template_desc_current(); |
f68c05f4 DK |
222 | if ((action & IMA_APPRAISE_SUBMASK) || |
223 | strcmp(template_desc->name, IMA_TEMPLATE_IMA_NAME) != 0) | |
1525b06d DK |
224 | /* read 'security.ima' */ |
225 | xattr_len = ima_read_xattr(file->f_path.dentry, &xattr_value); | |
d3634d0f | 226 | |
1525b06d DK |
227 | hash_algo = ima_get_hash_algo(xattr_value, xattr_len); |
228 | ||
cf222217 | 229 | rc = ima_collect_measurement(iint, file, buf, size, hash_algo); |
f9b2a735 MZ |
230 | if (rc != 0) { |
231 | if (file->f_flags & O_DIRECT) | |
232 | rc = (iint->flags & IMA_PERMIT_DIRECTIO) ? 0 : -EACCES; | |
a175b8bb | 233 | goto out_digsig; |
f9b2a735 | 234 | } |
08e1b76a | 235 | |
f7a859ff RS |
236 | if (!pathname) /* ima_rdwr_violation possibly pre-fetched */ |
237 | pathname = ima_d_path(&file->f_path, &pathbuf); | |
08e1b76a | 238 | |
2fe5d6de | 239 | if (action & IMA_MEASURE) |
bcbc9b0c MZ |
240 | ima_store_measurement(iint, file, pathname, |
241 | xattr_value, xattr_len); | |
d79d72e0 | 242 | if (action & IMA_APPRAISE_SUBMASK) |
4ad87a3d | 243 | rc = ima_appraise_measurement(func, iint, file, pathname, |
3034a146 | 244 | xattr_value, xattr_len, opened); |
e7c568e0 | 245 | if (action & IMA_AUDIT) |
ea1046d4 | 246 | ima_audit_measurement(iint, pathname); |
f7a859ff | 247 | |
a175b8bb DK |
248 | out_digsig: |
249 | if ((mask & MAY_WRITE) && (iint->flags & IMA_DIGSIG)) | |
250 | rc = -EACCES; | |
f7a859ff RS |
251 | kfree(xattr_value); |
252 | out_free: | |
456f5fd3 DK |
253 | if (pathbuf) |
254 | __putname(pathbuf); | |
3323eec9 | 255 | out: |
5955102c | 256 | inode_unlock(inode); |
750943a3 DK |
257 | if ((rc && must_appraise) && (ima_appraise & IMA_APPRAISE_ENFORCE)) |
258 | return -EACCES; | |
259 | return 0; | |
3323eec9 MZ |
260 | } |
261 | ||
262 | /** | |
263 | * ima_file_mmap - based on policy, collect/store measurement. | |
264 | * @file: pointer to the file to be measured (May be NULL) | |
265 | * @prot: contains the protection that will be applied by the kernel. | |
266 | * | |
267 | * Measure files being mmapped executable based on the ima_must_measure() | |
268 | * policy decision. | |
269 | * | |
750943a3 DK |
270 | * On success return 0. On integrity appraisal error, assuming the file |
271 | * is in policy and IMA-appraisal is in enforcing mode, return -EACCES. | |
3323eec9 MZ |
272 | */ |
273 | int ima_file_mmap(struct file *file, unsigned long prot) | |
274 | { | |
750943a3 | 275 | if (file && (prot & PROT_EXEC)) |
cf222217 MZ |
276 | return process_measurement(file, NULL, 0, MAY_EXEC, |
277 | MMAP_CHECK, 0); | |
750943a3 | 278 | return 0; |
3323eec9 MZ |
279 | } |
280 | ||
281 | /** | |
282 | * ima_bprm_check - based on policy, collect/store measurement. | |
283 | * @bprm: contains the linux_binprm structure | |
284 | * | |
285 | * The OS protects against an executable file, already open for write, | |
286 | * from being executed in deny_write_access() and an executable file, | |
287 | * already open for execute, from being modified in get_write_access(). | |
288 | * So we can be certain that what we verify and measure here is actually | |
289 | * what is being executed. | |
290 | * | |
750943a3 DK |
291 | * On success return 0. On integrity appraisal error, assuming the file |
292 | * is in policy and IMA-appraisal is in enforcing mode, return -EACCES. | |
3323eec9 MZ |
293 | */ |
294 | int ima_bprm_check(struct linux_binprm *bprm) | |
295 | { | |
cf222217 MZ |
296 | return process_measurement(bprm->file, NULL, 0, MAY_EXEC, |
297 | BPRM_CHECK, 0); | |
3323eec9 MZ |
298 | } |
299 | ||
8eb988c7 MZ |
300 | /** |
301 | * ima_path_check - based on policy, collect/store measurement. | |
302 | * @file: pointer to the file to be measured | |
303 | * @mask: contains MAY_READ, MAY_WRITE or MAY_EXECUTE | |
304 | * | |
305 | * Measure files based on the ima_must_measure() policy decision. | |
306 | * | |
750943a3 DK |
307 | * On success return 0. On integrity appraisal error, assuming the file |
308 | * is in policy and IMA-appraisal is in enforcing mode, return -EACCES. | |
8eb988c7 | 309 | */ |
3034a146 | 310 | int ima_file_check(struct file *file, int mask, int opened) |
8eb988c7 | 311 | { |
cf222217 | 312 | return process_measurement(file, NULL, 0, |
089bc8e9 | 313 | mask & (MAY_READ | MAY_WRITE | MAY_EXEC), |
3034a146 | 314 | FILE_CHECK, opened); |
8eb988c7 | 315 | } |
9bbb6cad | 316 | EXPORT_SYMBOL_GPL(ima_file_check); |
8eb988c7 | 317 | |
39eeb4fb MZ |
318 | /** |
319 | * ima_read_file - pre-measure/appraise hook decision based on policy | |
320 | * @file: pointer to the file to be measured/appraised/audit | |
321 | * @read_id: caller identifier | |
322 | * | |
323 | * Permit reading a file based on policy. The policy rules are written | |
324 | * in terms of the policy identifier. Appraising the integrity of | |
325 | * a file requires a file descriptor. | |
326 | * | |
327 | * For permission return 0, otherwise return -EACCES. | |
328 | */ | |
329 | int ima_read_file(struct file *file, enum kernel_read_file_id read_id) | |
330 | { | |
a1db7420 MZ |
331 | if (!file && read_id == READING_MODULE) { |
332 | #ifndef CONFIG_MODULE_SIG_FORCE | |
333 | if ((ima_appraise & IMA_APPRAISE_MODULES) && | |
334 | (ima_appraise & IMA_APPRAISE_ENFORCE)) | |
335 | return -EACCES; /* INTEGRITY_UNKNOWN */ | |
336 | #endif | |
337 | return 0; /* We rely on module signature checking */ | |
338 | } | |
39eeb4fb MZ |
339 | return 0; |
340 | } | |
341 | ||
d9ddf077 MZ |
342 | static int read_idmap[READING_MAX_ID] = { |
343 | [READING_FIRMWARE] = FIRMWARE_CHECK, | |
344 | [READING_MODULE] = MODULE_CHECK, | |
345 | [READING_KEXEC_IMAGE] = KEXEC_KERNEL_CHECK, | |
346 | [READING_KEXEC_INITRAMFS] = KEXEC_INITRAMFS_CHECK, | |
19f8a847 | 347 | [READING_POLICY] = POLICY_CHECK |
d9ddf077 MZ |
348 | }; |
349 | ||
cf222217 MZ |
350 | /** |
351 | * ima_post_read_file - in memory collect/appraise/audit measurement | |
352 | * @file: pointer to the file to be measured/appraised/audit | |
353 | * @buf: pointer to in memory file contents | |
354 | * @size: size of in memory file contents | |
355 | * @read_id: caller identifier | |
356 | * | |
357 | * Measure/appraise/audit in memory file based on policy. Policy rules | |
358 | * are written in terms of a policy identifier. | |
359 | * | |
360 | * On success return 0. On integrity appraisal error, assuming the file | |
361 | * is in policy and IMA-appraisal is in enforcing mode, return -EACCES. | |
362 | */ | |
363 | int ima_post_read_file(struct file *file, void *buf, loff_t size, | |
364 | enum kernel_read_file_id read_id) | |
365 | { | |
d9ddf077 | 366 | enum ima_hooks func; |
cf222217 | 367 | |
e40ba6d5 MZ |
368 | if (!file && read_id == READING_FIRMWARE) { |
369 | if ((ima_appraise & IMA_APPRAISE_FIRMWARE) && | |
370 | (ima_appraise & IMA_APPRAISE_ENFORCE)) | |
371 | return -EACCES; /* INTEGRITY_UNKNOWN */ | |
372 | return 0; | |
373 | } | |
374 | ||
a1db7420 MZ |
375 | if (!file && read_id == READING_MODULE) /* MODULE_SIG_FORCE enabled */ |
376 | return 0; | |
377 | ||
cf222217 MZ |
378 | if (!file || !buf || size == 0) { /* should never happen */ |
379 | if (ima_appraise & IMA_APPRAISE_ENFORCE) | |
380 | return -EACCES; | |
381 | return 0; | |
382 | } | |
383 | ||
d9ddf077 | 384 | func = read_idmap[read_id] ?: FILE_CHECK; |
cf222217 | 385 | return process_measurement(file, buf, size, MAY_READ, func, 0); |
5a9196d7 MZ |
386 | } |
387 | ||
3323eec9 MZ |
388 | static int __init init_ima(void) |
389 | { | |
390 | int error; | |
391 | ||
e7a2ad7e | 392 | hash_setup(CONFIG_IMA_DEFAULT_HASH); |
3323eec9 | 393 | error = ima_init(); |
a756024e | 394 | if (!error) { |
31b70f66 | 395 | ima_initialized = 1; |
a756024e RS |
396 | ima_update_policy_flag(); |
397 | } | |
3323eec9 MZ |
398 | return error; |
399 | } | |
400 | ||
401 | late_initcall(init_ima); /* Start IMA after the TPM is available */ | |
402 | ||
403 | MODULE_DESCRIPTION("Integrity Measurement Architecture"); | |
404 | MODULE_LICENSE("GPL"); |