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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 | */ | |
890275b5 | 80 | static void ima_rdwr_violation_check(struct file *file) |
8eb988c7 | 81 | { |
c77cecee | 82 | struct inode *inode = file_inode(file); |
8eb988c7 | 83 | fmode_t mode = file->f_mode; |
ad16ad00 | 84 | bool send_tomtou = false, send_writers = false; |
ea1046d4 DK |
85 | char *pathbuf = NULL; |
86 | const char *pathname; | |
8eb988c7 | 87 | |
890275b5 | 88 | if (!S_ISREG(inode->i_mode) || !ima_initialized) |
8eb988c7 | 89 | return; |
a178d202 | 90 | |
8eb988c7 | 91 | if (mode & FMODE_WRITE) { |
14503eb9 DK |
92 | if (atomic_read(&inode->i_readcount) && IS_IMA(inode)) { |
93 | struct integrity_iint_cache *iint; | |
94 | iint = integrity_iint_find(inode); | |
95 | /* IMA_MEASURE is set from reader side */ | |
96 | if (iint && (iint->flags & IMA_MEASURE)) | |
97 | send_tomtou = true; | |
98 | } | |
b882fae2 DK |
99 | } else { |
100 | if ((atomic_read(&inode->i_writecount) > 0) && | |
101 | ima_must_measure(inode, MAY_READ, FILE_CHECK)) | |
102 | send_writers = true; | |
8eb988c7 | 103 | } |
ad16ad00 | 104 | |
08e1b76a MZ |
105 | if (!send_tomtou && !send_writers) |
106 | return; | |
107 | ||
ea1046d4 | 108 | pathname = ima_d_path(&file->f_path, &pathbuf); |
ea1046d4 | 109 | |
ad16ad00 | 110 | if (send_tomtou) |
7d802a22 | 111 | ima_add_violation(file, pathname, "invalid_pcr", "ToMToU"); |
ad16ad00 | 112 | if (send_writers) |
7d802a22 | 113 | ima_add_violation(file, pathname, |
08e1b76a MZ |
114 | "invalid_pcr", "open_writers"); |
115 | kfree(pathbuf); | |
8eb988c7 MZ |
116 | } |
117 | ||
f381c272 | 118 | static void ima_check_last_writer(struct integrity_iint_cache *iint, |
2fe5d6de | 119 | struct inode *inode, struct file *file) |
bc7d2a3e | 120 | { |
4b2a2c67 | 121 | fmode_t mode = file->f_mode; |
bc7d2a3e | 122 | |
2fe5d6de MZ |
123 | if (!(mode & FMODE_WRITE)) |
124 | return; | |
125 | ||
126 | mutex_lock(&inode->i_mutex); | |
127 | if (atomic_read(&inode->i_writecount) == 1 && | |
128 | iint->version != inode->i_version) { | |
45e2472e | 129 | iint->flags &= ~IMA_DONE_MASK; |
2fe5d6de MZ |
130 | if (iint->flags & IMA_APPRAISE) |
131 | ima_update_xattr(iint, file); | |
132 | } | |
133 | mutex_unlock(&inode->i_mutex); | |
bc7d2a3e EP |
134 | } |
135 | ||
3323eec9 MZ |
136 | /** |
137 | * ima_file_free - called on __fput() | |
138 | * @file: pointer to file structure being freed | |
139 | * | |
890275b5 | 140 | * Flag files that changed, based on i_version |
3323eec9 MZ |
141 | */ |
142 | void ima_file_free(struct file *file) | |
143 | { | |
496ad9aa | 144 | struct inode *inode = file_inode(file); |
f381c272 | 145 | struct integrity_iint_cache *iint; |
3323eec9 | 146 | |
e950598d | 147 | if (!iint_initialized || !S_ISREG(inode->i_mode)) |
3323eec9 | 148 | return; |
196f5181 | 149 | |
f381c272 | 150 | iint = integrity_iint_find(inode); |
854fdd55 MZ |
151 | if (!iint) |
152 | return; | |
3323eec9 | 153 | |
854fdd55 | 154 | ima_check_last_writer(iint, inode, file); |
3323eec9 MZ |
155 | } |
156 | ||
ea1046d4 | 157 | static int process_measurement(struct file *file, const char *filename, |
3323eec9 MZ |
158 | int mask, int function) |
159 | { | |
496ad9aa | 160 | struct inode *inode = file_inode(file); |
f381c272 | 161 | struct integrity_iint_cache *iint; |
209b43ca | 162 | struct ima_template_desc *template_desc; |
ea1046d4 DK |
163 | char *pathbuf = NULL; |
164 | const char *pathname = NULL; | |
5a73fcfa | 165 | int rc = -ENOMEM, action, must_appraise, _func; |
d3634d0f DK |
166 | struct evm_ima_xattr_data *xattr_value = NULL, **xattr_ptr = NULL; |
167 | int xattr_len = 0; | |
3323eec9 MZ |
168 | |
169 | if (!ima_initialized || !S_ISREG(inode->i_mode)) | |
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); |
2fe5d6de MZ |
177 | if (!action) |
178 | return 0; | |
179 | ||
2fe5d6de | 180 | must_appraise = action & IMA_APPRAISE; |
bc7d2a3e | 181 | |
5a73fcfa MZ |
182 | /* Is the appraise rule hook specific? */ |
183 | _func = (action & IMA_FILE_APPRAISE) ? FILE_CHECK : function; | |
184 | ||
2fe5d6de MZ |
185 | mutex_lock(&inode->i_mutex); |
186 | ||
bf2276d1 DK |
187 | iint = integrity_inode_get(inode); |
188 | if (!iint) | |
189 | goto out; | |
190 | ||
2fe5d6de | 191 | /* Determine if already appraised/measured based on bitmask |
d79d72e0 MZ |
192 | * (IMA_MEASURE, IMA_MEASURED, IMA_XXXX_APPRAISE, IMA_XXXX_APPRAISED, |
193 | * IMA_AUDIT, IMA_AUDITED) | |
194 | */ | |
2fe5d6de | 195 | iint->flags |= action; |
0e5a247c | 196 | action &= IMA_DO_MASK; |
45e2472e | 197 | action &= ~((iint->flags & IMA_DONE_MASK) >> 1); |
2fe5d6de MZ |
198 | |
199 | /* Nothing to do, just return existing appraised status */ | |
200 | if (!action) { | |
d79d72e0 | 201 | if (must_appraise) |
5a73fcfa | 202 | rc = ima_get_cache_status(iint, _func); |
a175b8bb | 203 | goto out_digsig; |
2fe5d6de | 204 | } |
3323eec9 | 205 | |
209b43ca | 206 | template_desc = ima_template_desc_current(); |
add1c05d RS |
207 | if (strcmp(template_desc->name, IMA_TEMPLATE_IMA_NAME) == 0) { |
208 | if (action & IMA_APPRAISE_SUBMASK) | |
209 | xattr_ptr = &xattr_value; | |
210 | } else | |
d3634d0f DK |
211 | xattr_ptr = &xattr_value; |
212 | ||
213 | rc = ima_collect_measurement(iint, file, xattr_ptr, &xattr_len); | |
f9b2a735 MZ |
214 | if (rc != 0) { |
215 | if (file->f_flags & O_DIRECT) | |
216 | rc = (iint->flags & IMA_PERMIT_DIRECTIO) ? 0 : -EACCES; | |
a175b8bb | 217 | goto out_digsig; |
f9b2a735 | 218 | } |
08e1b76a | 219 | |
61997c43 | 220 | pathname = filename ?: ima_d_path(&file->f_path, &pathbuf); |
08e1b76a | 221 | |
2fe5d6de | 222 | if (action & IMA_MEASURE) |
bcbc9b0c MZ |
223 | ima_store_measurement(iint, file, pathname, |
224 | xattr_value, xattr_len); | |
d79d72e0 | 225 | if (action & IMA_APPRAISE_SUBMASK) |
d3634d0f DK |
226 | rc = ima_appraise_measurement(_func, iint, file, pathname, |
227 | xattr_value, xattr_len); | |
e7c568e0 | 228 | if (action & IMA_AUDIT) |
ea1046d4 | 229 | ima_audit_measurement(iint, pathname); |
08e1b76a | 230 | kfree(pathbuf); |
a175b8bb DK |
231 | out_digsig: |
232 | if ((mask & MAY_WRITE) && (iint->flags & IMA_DIGSIG)) | |
233 | rc = -EACCES; | |
3323eec9 | 234 | out: |
2fe5d6de | 235 | mutex_unlock(&inode->i_mutex); |
d3634d0f | 236 | kfree(xattr_value); |
750943a3 DK |
237 | if ((rc && must_appraise) && (ima_appraise & IMA_APPRAISE_ENFORCE)) |
238 | return -EACCES; | |
239 | return 0; | |
3323eec9 MZ |
240 | } |
241 | ||
242 | /** | |
243 | * ima_file_mmap - based on policy, collect/store measurement. | |
244 | * @file: pointer to the file to be measured (May be NULL) | |
245 | * @prot: contains the protection that will be applied by the kernel. | |
246 | * | |
247 | * Measure files being mmapped executable based on the ima_must_measure() | |
248 | * policy decision. | |
249 | * | |
750943a3 DK |
250 | * On success return 0. On integrity appraisal error, assuming the file |
251 | * is in policy and IMA-appraisal is in enforcing mode, return -EACCES. | |
3323eec9 MZ |
252 | */ |
253 | int ima_file_mmap(struct file *file, unsigned long prot) | |
254 | { | |
750943a3 | 255 | if (file && (prot & PROT_EXEC)) |
df2c2afb | 256 | return process_measurement(file, NULL, MAY_EXEC, MMAP_CHECK); |
750943a3 | 257 | return 0; |
3323eec9 MZ |
258 | } |
259 | ||
260 | /** | |
261 | * ima_bprm_check - based on policy, collect/store measurement. | |
262 | * @bprm: contains the linux_binprm structure | |
263 | * | |
264 | * The OS protects against an executable file, already open for write, | |
265 | * from being executed in deny_write_access() and an executable file, | |
266 | * already open for execute, from being modified in get_write_access(). | |
267 | * So we can be certain that what we verify and measure here is actually | |
268 | * what is being executed. | |
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_bprm_check(struct linux_binprm *bprm) | |
274 | { | |
750943a3 | 275 | return process_measurement(bprm->file, |
089bc8e9 DK |
276 | (strcmp(bprm->filename, bprm->interp) == 0) ? |
277 | bprm->filename : bprm->interp, | |
278 | MAY_EXEC, BPRM_CHECK); | |
3323eec9 MZ |
279 | } |
280 | ||
8eb988c7 MZ |
281 | /** |
282 | * ima_path_check - based on policy, collect/store measurement. | |
283 | * @file: pointer to the file to be measured | |
284 | * @mask: contains MAY_READ, MAY_WRITE or MAY_EXECUTE | |
285 | * | |
286 | * Measure files based on the ima_must_measure() policy decision. | |
287 | * | |
750943a3 DK |
288 | * On success return 0. On integrity appraisal error, assuming the file |
289 | * is in policy and IMA-appraisal is in enforcing mode, return -EACCES. | |
8eb988c7 | 290 | */ |
9bbb6cad | 291 | int ima_file_check(struct file *file, int mask) |
8eb988c7 | 292 | { |
890275b5 | 293 | ima_rdwr_violation_check(file); |
df2c2afb | 294 | return process_measurement(file, NULL, |
089bc8e9 DK |
295 | mask & (MAY_READ | MAY_WRITE | MAY_EXEC), |
296 | FILE_CHECK); | |
8eb988c7 | 297 | } |
9bbb6cad | 298 | EXPORT_SYMBOL_GPL(ima_file_check); |
8eb988c7 | 299 | |
fdf90729 MZ |
300 | /** |
301 | * ima_module_check - based on policy, collect/store/appraise measurement. | |
302 | * @file: pointer to the file to be measured/appraised | |
303 | * | |
304 | * Measure/appraise kernel modules based on policy. | |
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. | |
fdf90729 MZ |
308 | */ |
309 | int ima_module_check(struct file *file) | |
310 | { | |
a7f2a366 | 311 | if (!file) { |
a7f2a366 | 312 | #ifndef CONFIG_MODULE_SIG_FORCE |
a2c2c3a7 MZ |
313 | if ((ima_appraise & IMA_APPRAISE_MODULES) && |
314 | (ima_appraise & IMA_APPRAISE_ENFORCE)) | |
33673dcb | 315 | return -EACCES; /* INTEGRITY_UNKNOWN */ |
a7f2a366 | 316 | #endif |
33673dcb LT |
317 | return 0; /* We rely on module signature checking */ |
318 | } | |
df2c2afb | 319 | return process_measurement(file, NULL, MAY_EXEC, MODULE_CHECK); |
fdf90729 MZ |
320 | } |
321 | ||
3323eec9 MZ |
322 | static int __init init_ima(void) |
323 | { | |
324 | int error; | |
325 | ||
e7a2ad7e | 326 | hash_setup(CONFIG_IMA_DEFAULT_HASH); |
3323eec9 | 327 | error = ima_init(); |
7d2ce232 MZ |
328 | if (error) |
329 | goto out; | |
330 | ||
331 | error = ima_init_keyring(INTEGRITY_KEYRING_IMA); | |
332 | if (error) | |
333 | goto out; | |
334 | ima_initialized = 1; | |
335 | out: | |
3323eec9 MZ |
336 | return error; |
337 | } | |
338 | ||
339 | late_initcall(init_ima); /* Start IMA after the TPM is available */ | |
340 | ||
341 | MODULE_DESCRIPTION("Integrity Measurement Architecture"); | |
342 | MODULE_LICENSE("GPL"); |