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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> |
c7c8bb23 | 27 | #include <crypto/hash_info.h> |
3323eec9 MZ |
28 | |
29 | #include "ima.h" | |
30 | ||
31 | int ima_initialized; | |
32 | ||
2fe5d6de MZ |
33 | #ifdef CONFIG_IMA_APPRAISE |
34 | int ima_appraise = IMA_APPRAISE_ENFORCE; | |
35 | #else | |
36 | int ima_appraise; | |
37 | #endif | |
38 | ||
c7c8bb23 | 39 | int ima_hash_algo = HASH_ALGO_SHA1; |
e7a2ad7e | 40 | static int hash_setup_done; |
c7c8bb23 | 41 | |
3323eec9 MZ |
42 | static int __init hash_setup(char *str) |
43 | { | |
e7a2ad7e MZ |
44 | struct ima_template_desc *template_desc = ima_template_desc_current(); |
45 | int i; | |
46 | ||
47 | if (hash_setup_done) | |
48 | return 1; | |
49 | ||
50 | if (strcmp(template_desc->name, IMA_TEMPLATE_IMA_NAME) == 0) { | |
51 | if (strncmp(str, "sha1", 4) == 0) | |
52 | ima_hash_algo = HASH_ALGO_SHA1; | |
53 | else if (strncmp(str, "md5", 3) == 0) | |
54 | ima_hash_algo = HASH_ALGO_MD5; | |
55 | goto out; | |
56 | } | |
57 | ||
58 | for (i = 0; i < HASH_ALGO__LAST; i++) { | |
59 | if (strcmp(str, hash_algo_name[i]) == 0) { | |
60 | ima_hash_algo = i; | |
61 | break; | |
62 | } | |
63 | } | |
64 | out: | |
65 | hash_setup_done = 1; | |
3323eec9 MZ |
66 | return 1; |
67 | } | |
68 | __setup("ima_hash=", hash_setup); | |
69 | ||
8eb988c7 | 70 | /* |
890275b5 | 71 | * ima_rdwr_violation_check |
8eb988c7 | 72 | * |
890275b5 | 73 | * Only invalidate the PCR for measured files: |
2bb930ab | 74 | * - Opening a file for write when already open for read, |
8eb988c7 MZ |
75 | * results in a time of measure, time of use (ToMToU) error. |
76 | * - Opening a file for read when already open for write, | |
2bb930ab | 77 | * could result in a file measurement error. |
8eb988c7 MZ |
78 | * |
79 | */ | |
f7a859ff RS |
80 | static void ima_rdwr_violation_check(struct file *file, |
81 | struct integrity_iint_cache *iint, | |
1b68bdf9 | 82 | int must_measure, |
f7a859ff RS |
83 | char **pathbuf, |
84 | const char **pathname) | |
8eb988c7 | 85 | { |
c77cecee | 86 | struct inode *inode = file_inode(file); |
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 | ||
f7a859ff | 106 | *pathname = ima_d_path(&file->f_path, pathbuf); |
ea1046d4 | 107 | |
ad16ad00 | 108 | if (send_tomtou) |
f7a859ff | 109 | ima_add_violation(file, *pathname, "invalid_pcr", "ToMToU"); |
ad16ad00 | 110 | if (send_writers) |
f7a859ff | 111 | ima_add_violation(file, *pathname, |
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 | ||
123 | mutex_lock(&inode->i_mutex); | |
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 MZ |
131 | } |
132 | mutex_unlock(&inode->i_mutex); | |
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 | ||
17f4bad3 DK |
156 | static int process_measurement(struct file *file, int mask, int function, |
157 | 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; |
d3634d0f DK |
165 | struct evm_ima_xattr_data *xattr_value = NULL, **xattr_ptr = NULL; |
166 | int xattr_len = 0; | |
f7a859ff | 167 | bool violation_check; |
3323eec9 | 168 | |
a756024e | 169 | if (!ima_policy_flag || !S_ISREG(inode->i_mode)) |
3323eec9 | 170 | return 0; |
bc7d2a3e | 171 | |
d79d72e0 MZ |
172 | /* Return an IMA_MEASURE, IMA_APPRAISE, IMA_AUDIT action |
173 | * bitmask based on the appraise/audit/measurement policy. | |
174 | * Included is the appraise submask. | |
175 | */ | |
d9d300cd | 176 | action = ima_get_action(inode, mask, function); |
1b68bdf9 | 177 | violation_check = ((function == FILE_CHECK || function == MMAP_CHECK) && |
f7a859ff RS |
178 | (ima_policy_flag & IMA_MEASURE)); |
179 | if (!action && !violation_check) | |
2fe5d6de MZ |
180 | return 0; |
181 | ||
2fe5d6de | 182 | must_appraise = action & IMA_APPRAISE; |
bc7d2a3e | 183 | |
5a73fcfa | 184 | /* Is the appraise rule hook specific? */ |
3a8a2ead DK |
185 | if (action & IMA_FILE_APPRAISE) |
186 | function = FILE_CHECK; | |
5a73fcfa | 187 | |
2fe5d6de MZ |
188 | mutex_lock(&inode->i_mutex); |
189 | ||
f7a859ff RS |
190 | if (action) { |
191 | iint = integrity_inode_get(inode); | |
192 | if (!iint) | |
193 | goto out; | |
194 | } | |
195 | ||
196 | if (violation_check) { | |
1b68bdf9 RS |
197 | ima_rdwr_violation_check(file, iint, action & IMA_MEASURE, |
198 | &pathbuf, &pathname); | |
f7a859ff RS |
199 | if (!action) { |
200 | rc = 0; | |
201 | goto out_free; | |
202 | } | |
203 | } | |
bf2276d1 | 204 | |
2fe5d6de | 205 | /* Determine if already appraised/measured based on bitmask |
d79d72e0 MZ |
206 | * (IMA_MEASURE, IMA_MEASURED, IMA_XXXX_APPRAISE, IMA_XXXX_APPRAISED, |
207 | * IMA_AUDIT, IMA_AUDITED) | |
208 | */ | |
2fe5d6de | 209 | iint->flags |= action; |
0e5a247c | 210 | action &= IMA_DO_MASK; |
45e2472e | 211 | action &= ~((iint->flags & IMA_DONE_MASK) >> 1); |
2fe5d6de MZ |
212 | |
213 | /* Nothing to do, just return existing appraised status */ | |
214 | if (!action) { | |
d79d72e0 | 215 | if (must_appraise) |
3a8a2ead | 216 | rc = ima_get_cache_status(iint, function); |
a175b8bb | 217 | goto out_digsig; |
2fe5d6de | 218 | } |
3323eec9 | 219 | |
209b43ca | 220 | template_desc = ima_template_desc_current(); |
f68c05f4 DK |
221 | if ((action & IMA_APPRAISE_SUBMASK) || |
222 | strcmp(template_desc->name, IMA_TEMPLATE_IMA_NAME) != 0) | |
d3634d0f DK |
223 | xattr_ptr = &xattr_value; |
224 | ||
225 | rc = ima_collect_measurement(iint, file, xattr_ptr, &xattr_len); | |
f9b2a735 MZ |
226 | if (rc != 0) { |
227 | if (file->f_flags & O_DIRECT) | |
228 | rc = (iint->flags & IMA_PERMIT_DIRECTIO) ? 0 : -EACCES; | |
a175b8bb | 229 | goto out_digsig; |
f9b2a735 | 230 | } |
08e1b76a | 231 | |
f7a859ff RS |
232 | if (!pathname) /* ima_rdwr_violation possibly pre-fetched */ |
233 | pathname = ima_d_path(&file->f_path, &pathbuf); | |
08e1b76a | 234 | |
2fe5d6de | 235 | if (action & IMA_MEASURE) |
bcbc9b0c MZ |
236 | ima_store_measurement(iint, file, pathname, |
237 | xattr_value, xattr_len); | |
d79d72e0 | 238 | if (action & IMA_APPRAISE_SUBMASK) |
3a8a2ead | 239 | rc = ima_appraise_measurement(function, iint, file, pathname, |
3034a146 | 240 | xattr_value, xattr_len, opened); |
e7c568e0 | 241 | if (action & IMA_AUDIT) |
ea1046d4 | 242 | ima_audit_measurement(iint, pathname); |
f7a859ff | 243 | |
a175b8bb DK |
244 | out_digsig: |
245 | if ((mask & MAY_WRITE) && (iint->flags & IMA_DIGSIG)) | |
246 | rc = -EACCES; | |
f7a859ff RS |
247 | kfree(xattr_value); |
248 | out_free: | |
456f5fd3 DK |
249 | if (pathbuf) |
250 | __putname(pathbuf); | |
3323eec9 | 251 | out: |
2fe5d6de | 252 | mutex_unlock(&inode->i_mutex); |
750943a3 DK |
253 | if ((rc && must_appraise) && (ima_appraise & IMA_APPRAISE_ENFORCE)) |
254 | return -EACCES; | |
255 | return 0; | |
3323eec9 MZ |
256 | } |
257 | ||
258 | /** | |
259 | * ima_file_mmap - based on policy, collect/store measurement. | |
260 | * @file: pointer to the file to be measured (May be NULL) | |
261 | * @prot: contains the protection that will be applied by the kernel. | |
262 | * | |
263 | * Measure files being mmapped executable based on the ima_must_measure() | |
264 | * policy decision. | |
265 | * | |
750943a3 DK |
266 | * On success return 0. On integrity appraisal error, assuming the file |
267 | * is in policy and IMA-appraisal is in enforcing mode, return -EACCES. | |
3323eec9 MZ |
268 | */ |
269 | int ima_file_mmap(struct file *file, unsigned long prot) | |
270 | { | |
750943a3 | 271 | if (file && (prot & PROT_EXEC)) |
17f4bad3 | 272 | return process_measurement(file, MAY_EXEC, MMAP_CHECK, 0); |
750943a3 | 273 | return 0; |
3323eec9 MZ |
274 | } |
275 | ||
276 | /** | |
277 | * ima_bprm_check - based on policy, collect/store measurement. | |
278 | * @bprm: contains the linux_binprm structure | |
279 | * | |
280 | * The OS protects against an executable file, already open for write, | |
281 | * from being executed in deny_write_access() and an executable file, | |
282 | * already open for execute, from being modified in get_write_access(). | |
283 | * So we can be certain that what we verify and measure here is actually | |
284 | * what is being executed. | |
285 | * | |
750943a3 DK |
286 | * On success return 0. On integrity appraisal error, assuming the file |
287 | * is in policy and IMA-appraisal is in enforcing mode, return -EACCES. | |
3323eec9 MZ |
288 | */ |
289 | int ima_bprm_check(struct linux_binprm *bprm) | |
290 | { | |
17f4bad3 | 291 | return process_measurement(bprm->file, MAY_EXEC, BPRM_CHECK, 0); |
3323eec9 MZ |
292 | } |
293 | ||
8eb988c7 MZ |
294 | /** |
295 | * ima_path_check - based on policy, collect/store measurement. | |
296 | * @file: pointer to the file to be measured | |
297 | * @mask: contains MAY_READ, MAY_WRITE or MAY_EXECUTE | |
298 | * | |
299 | * Measure files based on the ima_must_measure() policy decision. | |
300 | * | |
750943a3 DK |
301 | * On success return 0. On integrity appraisal error, assuming the file |
302 | * is in policy and IMA-appraisal is in enforcing mode, return -EACCES. | |
8eb988c7 | 303 | */ |
3034a146 | 304 | int ima_file_check(struct file *file, int mask, int opened) |
8eb988c7 | 305 | { |
17f4bad3 | 306 | return process_measurement(file, |
089bc8e9 | 307 | mask & (MAY_READ | MAY_WRITE | MAY_EXEC), |
3034a146 | 308 | FILE_CHECK, opened); |
8eb988c7 | 309 | } |
9bbb6cad | 310 | EXPORT_SYMBOL_GPL(ima_file_check); |
8eb988c7 | 311 | |
fdf90729 MZ |
312 | /** |
313 | * ima_module_check - based on policy, collect/store/appraise measurement. | |
314 | * @file: pointer to the file to be measured/appraised | |
315 | * | |
316 | * Measure/appraise kernel modules based on policy. | |
317 | * | |
750943a3 DK |
318 | * On success return 0. On integrity appraisal error, assuming the file |
319 | * is in policy and IMA-appraisal is in enforcing mode, return -EACCES. | |
fdf90729 MZ |
320 | */ |
321 | int ima_module_check(struct file *file) | |
322 | { | |
a7f2a366 | 323 | if (!file) { |
a7f2a366 | 324 | #ifndef CONFIG_MODULE_SIG_FORCE |
a2c2c3a7 MZ |
325 | if ((ima_appraise & IMA_APPRAISE_MODULES) && |
326 | (ima_appraise & IMA_APPRAISE_ENFORCE)) | |
33673dcb | 327 | return -EACCES; /* INTEGRITY_UNKNOWN */ |
a7f2a366 | 328 | #endif |
33673dcb LT |
329 | return 0; /* We rely on module signature checking */ |
330 | } | |
17f4bad3 | 331 | return process_measurement(file, MAY_EXEC, MODULE_CHECK, 0); |
fdf90729 MZ |
332 | } |
333 | ||
5a9196d7 MZ |
334 | int ima_fw_from_file(struct file *file, char *buf, size_t size) |
335 | { | |
336 | if (!file) { | |
337 | if ((ima_appraise & IMA_APPRAISE_FIRMWARE) && | |
338 | (ima_appraise & IMA_APPRAISE_ENFORCE)) | |
339 | return -EACCES; /* INTEGRITY_UNKNOWN */ | |
340 | return 0; | |
341 | } | |
17f4bad3 | 342 | return process_measurement(file, MAY_EXEC, FIRMWARE_CHECK, 0); |
5a9196d7 MZ |
343 | } |
344 | ||
3323eec9 MZ |
345 | static int __init init_ima(void) |
346 | { | |
347 | int error; | |
348 | ||
e7a2ad7e | 349 | hash_setup(CONFIG_IMA_DEFAULT_HASH); |
3323eec9 | 350 | error = ima_init(); |
a756024e | 351 | if (!error) { |
31b70f66 | 352 | ima_initialized = 1; |
a756024e RS |
353 | ima_update_policy_flag(); |
354 | } | |
3323eec9 MZ |
355 | return error; |
356 | } | |
357 | ||
358 | late_initcall(init_ima); /* Start IMA after the TPM is available */ | |
359 | ||
360 | MODULE_DESCRIPTION("Integrity Measurement Architecture"); | |
361 | MODULE_LICENSE("GPL"); |