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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 | ||
3323eec9 MZ |
38 | char *ima_hash = "sha1"; |
39 | static int __init hash_setup(char *str) | |
40 | { | |
07ff7a0b MZ |
41 | if (strncmp(str, "md5", 3) == 0) |
42 | ima_hash = "md5"; | |
3323eec9 MZ |
43 | return 1; |
44 | } | |
45 | __setup("ima_hash=", hash_setup); | |
46 | ||
8eb988c7 | 47 | /* |
890275b5 | 48 | * ima_rdwr_violation_check |
8eb988c7 | 49 | * |
890275b5 | 50 | * Only invalidate the PCR for measured files: |
8eb988c7 MZ |
51 | * - Opening a file for write when already open for read, |
52 | * results in a time of measure, time of use (ToMToU) error. | |
53 | * - Opening a file for read when already open for write, | |
54 | * could result in a file measurement error. | |
55 | * | |
56 | */ | |
890275b5 | 57 | static void ima_rdwr_violation_check(struct file *file) |
8eb988c7 MZ |
58 | { |
59 | struct dentry *dentry = file->f_path.dentry; | |
c77cecee | 60 | struct inode *inode = file_inode(file); |
8eb988c7 | 61 | fmode_t mode = file->f_mode; |
2fe5d6de | 62 | int must_measure; |
ad16ad00 | 63 | bool send_tomtou = false, send_writers = false; |
ea1046d4 DK |
64 | char *pathbuf = NULL; |
65 | const char *pathname; | |
8eb988c7 | 66 | |
890275b5 | 67 | if (!S_ISREG(inode->i_mode) || !ima_initialized) |
8eb988c7 | 68 | return; |
a178d202 | 69 | |
890275b5 | 70 | mutex_lock(&inode->i_mutex); /* file metadata: permissions, xattr */ |
ad16ad00 | 71 | |
8eb988c7 | 72 | if (mode & FMODE_WRITE) { |
a68a27b6 | 73 | if (atomic_read(&inode->i_readcount) && IS_IMA(inode)) |
ad16ad00 | 74 | send_tomtou = true; |
8eb988c7 MZ |
75 | goto out; |
76 | } | |
ad16ad00 | 77 | |
2fe5d6de MZ |
78 | must_measure = ima_must_measure(inode, MAY_READ, FILE_CHECK); |
79 | if (!must_measure) | |
bade72d6 EP |
80 | goto out; |
81 | ||
ad16ad00 EP |
82 | if (atomic_read(&inode->i_writecount) > 0) |
83 | send_writers = true; | |
8eb988c7 | 84 | out: |
890275b5 | 85 | mutex_unlock(&inode->i_mutex); |
ad16ad00 | 86 | |
08e1b76a MZ |
87 | if (!send_tomtou && !send_writers) |
88 | return; | |
89 | ||
ea1046d4 DK |
90 | pathname = ima_d_path(&file->f_path, &pathbuf); |
91 | if (!pathname || strlen(pathname) > IMA_EVENT_NAME_LEN_MAX) | |
92 | pathname = dentry->d_name.name; | |
93 | ||
ad16ad00 | 94 | if (send_tomtou) |
ea1046d4 | 95 | ima_add_violation(inode, pathname, |
08e1b76a | 96 | "invalid_pcr", "ToMToU"); |
ad16ad00 | 97 | if (send_writers) |
ea1046d4 | 98 | ima_add_violation(inode, pathname, |
08e1b76a MZ |
99 | "invalid_pcr", "open_writers"); |
100 | kfree(pathbuf); | |
8eb988c7 MZ |
101 | } |
102 | ||
f381c272 | 103 | static void ima_check_last_writer(struct integrity_iint_cache *iint, |
2fe5d6de | 104 | struct inode *inode, struct file *file) |
bc7d2a3e | 105 | { |
4b2a2c67 | 106 | fmode_t mode = file->f_mode; |
bc7d2a3e | 107 | |
2fe5d6de MZ |
108 | if (!(mode & FMODE_WRITE)) |
109 | return; | |
110 | ||
111 | mutex_lock(&inode->i_mutex); | |
112 | if (atomic_read(&inode->i_writecount) == 1 && | |
113 | iint->version != inode->i_version) { | |
45e2472e | 114 | iint->flags &= ~IMA_DONE_MASK; |
2fe5d6de MZ |
115 | if (iint->flags & IMA_APPRAISE) |
116 | ima_update_xattr(iint, file); | |
117 | } | |
118 | mutex_unlock(&inode->i_mutex); | |
bc7d2a3e EP |
119 | } |
120 | ||
3323eec9 MZ |
121 | /** |
122 | * ima_file_free - called on __fput() | |
123 | * @file: pointer to file structure being freed | |
124 | * | |
890275b5 | 125 | * Flag files that changed, based on i_version |
3323eec9 MZ |
126 | */ |
127 | void ima_file_free(struct file *file) | |
128 | { | |
496ad9aa | 129 | struct inode *inode = file_inode(file); |
f381c272 | 130 | struct integrity_iint_cache *iint; |
3323eec9 | 131 | |
e950598d | 132 | if (!iint_initialized || !S_ISREG(inode->i_mode)) |
3323eec9 | 133 | return; |
196f5181 | 134 | |
f381c272 | 135 | iint = integrity_iint_find(inode); |
854fdd55 MZ |
136 | if (!iint) |
137 | return; | |
3323eec9 | 138 | |
854fdd55 | 139 | ima_check_last_writer(iint, inode, file); |
3323eec9 MZ |
140 | } |
141 | ||
ea1046d4 | 142 | static int process_measurement(struct file *file, const char *filename, |
3323eec9 MZ |
143 | int mask, int function) |
144 | { | |
496ad9aa | 145 | struct inode *inode = file_inode(file); |
f381c272 | 146 | struct integrity_iint_cache *iint; |
ea1046d4 DK |
147 | char *pathbuf = NULL; |
148 | const char *pathname = NULL; | |
5a73fcfa | 149 | int rc = -ENOMEM, action, must_appraise, _func; |
3323eec9 MZ |
150 | |
151 | if (!ima_initialized || !S_ISREG(inode->i_mode)) | |
152 | return 0; | |
bc7d2a3e | 153 | |
d79d72e0 MZ |
154 | /* Return an IMA_MEASURE, IMA_APPRAISE, IMA_AUDIT action |
155 | * bitmask based on the appraise/audit/measurement policy. | |
156 | * Included is the appraise submask. | |
157 | */ | |
d9d300cd | 158 | action = ima_get_action(inode, mask, function); |
2fe5d6de MZ |
159 | if (!action) |
160 | return 0; | |
161 | ||
2fe5d6de | 162 | must_appraise = action & IMA_APPRAISE; |
bc7d2a3e | 163 | |
5a73fcfa MZ |
164 | /* Is the appraise rule hook specific? */ |
165 | _func = (action & IMA_FILE_APPRAISE) ? FILE_CHECK : function; | |
166 | ||
2fe5d6de MZ |
167 | mutex_lock(&inode->i_mutex); |
168 | ||
bf2276d1 DK |
169 | iint = integrity_inode_get(inode); |
170 | if (!iint) | |
171 | goto out; | |
172 | ||
2fe5d6de | 173 | /* Determine if already appraised/measured based on bitmask |
d79d72e0 MZ |
174 | * (IMA_MEASURE, IMA_MEASURED, IMA_XXXX_APPRAISE, IMA_XXXX_APPRAISED, |
175 | * IMA_AUDIT, IMA_AUDITED) | |
176 | */ | |
2fe5d6de | 177 | iint->flags |= action; |
0e5a247c | 178 | action &= IMA_DO_MASK; |
45e2472e | 179 | action &= ~((iint->flags & IMA_DONE_MASK) >> 1); |
2fe5d6de MZ |
180 | |
181 | /* Nothing to do, just return existing appraised status */ | |
182 | if (!action) { | |
d79d72e0 | 183 | if (must_appraise) |
5a73fcfa | 184 | rc = ima_get_cache_status(iint, _func); |
a175b8bb | 185 | goto out_digsig; |
2fe5d6de | 186 | } |
3323eec9 MZ |
187 | |
188 | rc = ima_collect_measurement(iint, file); | |
08e1b76a | 189 | if (rc != 0) |
a175b8bb | 190 | goto out_digsig; |
08e1b76a | 191 | |
df2c2afb | 192 | pathname = !filename ? ima_d_path(&file->f_path, &pathbuf) : filename; |
ea1046d4 | 193 | if (!pathname) |
df2c2afb | 194 | pathname = (const char *)file->f_dentry->d_name.name; |
08e1b76a | 195 | |
2fe5d6de | 196 | if (action & IMA_MEASURE) |
ea1046d4 | 197 | ima_store_measurement(iint, file, pathname); |
d79d72e0 | 198 | if (action & IMA_APPRAISE_SUBMASK) |
5a73fcfa | 199 | rc = ima_appraise_measurement(_func, iint, file, pathname); |
e7c568e0 | 200 | if (action & IMA_AUDIT) |
ea1046d4 | 201 | ima_audit_measurement(iint, pathname); |
08e1b76a | 202 | kfree(pathbuf); |
a175b8bb DK |
203 | out_digsig: |
204 | if ((mask & MAY_WRITE) && (iint->flags & IMA_DIGSIG)) | |
205 | rc = -EACCES; | |
3323eec9 | 206 | out: |
2fe5d6de | 207 | mutex_unlock(&inode->i_mutex); |
750943a3 DK |
208 | if ((rc && must_appraise) && (ima_appraise & IMA_APPRAISE_ENFORCE)) |
209 | return -EACCES; | |
210 | return 0; | |
3323eec9 MZ |
211 | } |
212 | ||
213 | /** | |
214 | * ima_file_mmap - based on policy, collect/store measurement. | |
215 | * @file: pointer to the file to be measured (May be NULL) | |
216 | * @prot: contains the protection that will be applied by the kernel. | |
217 | * | |
218 | * Measure files being mmapped executable based on the ima_must_measure() | |
219 | * policy decision. | |
220 | * | |
750943a3 DK |
221 | * On success return 0. On integrity appraisal error, assuming the file |
222 | * is in policy and IMA-appraisal is in enforcing mode, return -EACCES. | |
3323eec9 MZ |
223 | */ |
224 | int ima_file_mmap(struct file *file, unsigned long prot) | |
225 | { | |
750943a3 | 226 | if (file && (prot & PROT_EXEC)) |
df2c2afb | 227 | return process_measurement(file, NULL, MAY_EXEC, MMAP_CHECK); |
750943a3 | 228 | return 0; |
3323eec9 MZ |
229 | } |
230 | ||
231 | /** | |
232 | * ima_bprm_check - based on policy, collect/store measurement. | |
233 | * @bprm: contains the linux_binprm structure | |
234 | * | |
235 | * The OS protects against an executable file, already open for write, | |
236 | * from being executed in deny_write_access() and an executable file, | |
237 | * already open for execute, from being modified in get_write_access(). | |
238 | * So we can be certain that what we verify and measure here is actually | |
239 | * what is being executed. | |
240 | * | |
750943a3 DK |
241 | * On success return 0. On integrity appraisal error, assuming the file |
242 | * is in policy and IMA-appraisal is in enforcing mode, return -EACCES. | |
3323eec9 MZ |
243 | */ |
244 | int ima_bprm_check(struct linux_binprm *bprm) | |
245 | { | |
750943a3 | 246 | return process_measurement(bprm->file, |
fbbb4563 MZ |
247 | (strcmp(bprm->filename, bprm->interp) == 0) ? |
248 | bprm->filename : bprm->interp, | |
3323eec9 | 249 | MAY_EXEC, BPRM_CHECK); |
3323eec9 MZ |
250 | } |
251 | ||
8eb988c7 MZ |
252 | /** |
253 | * ima_path_check - based on policy, collect/store measurement. | |
254 | * @file: pointer to the file to be measured | |
255 | * @mask: contains MAY_READ, MAY_WRITE or MAY_EXECUTE | |
256 | * | |
257 | * Measure files based on the ima_must_measure() policy decision. | |
258 | * | |
750943a3 DK |
259 | * On success return 0. On integrity appraisal error, assuming the file |
260 | * is in policy and IMA-appraisal is in enforcing mode, return -EACCES. | |
8eb988c7 | 261 | */ |
9bbb6cad | 262 | int ima_file_check(struct file *file, int mask) |
8eb988c7 | 263 | { |
890275b5 | 264 | ima_rdwr_violation_check(file); |
df2c2afb | 265 | return process_measurement(file, NULL, |
8eb988c7 | 266 | mask & (MAY_READ | MAY_WRITE | MAY_EXEC), |
1e93d005 | 267 | FILE_CHECK); |
8eb988c7 | 268 | } |
9bbb6cad | 269 | EXPORT_SYMBOL_GPL(ima_file_check); |
8eb988c7 | 270 | |
fdf90729 MZ |
271 | /** |
272 | * ima_module_check - based on policy, collect/store/appraise measurement. | |
273 | * @file: pointer to the file to be measured/appraised | |
274 | * | |
275 | * Measure/appraise kernel modules based on policy. | |
276 | * | |
750943a3 DK |
277 | * On success return 0. On integrity appraisal error, assuming the file |
278 | * is in policy and IMA-appraisal is in enforcing mode, return -EACCES. | |
fdf90729 MZ |
279 | */ |
280 | int ima_module_check(struct file *file) | |
281 | { | |
a7f2a366 | 282 | if (!file) { |
a7f2a366 | 283 | #ifndef CONFIG_MODULE_SIG_FORCE |
a2c2c3a7 MZ |
284 | if ((ima_appraise & IMA_APPRAISE_MODULES) && |
285 | (ima_appraise & IMA_APPRAISE_ENFORCE)) | |
33673dcb | 286 | return -EACCES; /* INTEGRITY_UNKNOWN */ |
a7f2a366 | 287 | #endif |
33673dcb LT |
288 | return 0; /* We rely on module signature checking */ |
289 | } | |
df2c2afb | 290 | return process_measurement(file, NULL, MAY_EXEC, MODULE_CHECK); |
fdf90729 MZ |
291 | } |
292 | ||
3323eec9 MZ |
293 | static int __init init_ima(void) |
294 | { | |
295 | int error; | |
296 | ||
3323eec9 | 297 | error = ima_init(); |
7ff2267a DK |
298 | if (!error) |
299 | ima_initialized = 1; | |
3323eec9 MZ |
300 | return error; |
301 | } | |
302 | ||
303 | late_initcall(init_ima); /* Start IMA after the TPM is available */ | |
304 | ||
305 | MODULE_DESCRIPTION("Integrity Measurement Architecture"); | |
306 | MODULE_LICENSE("GPL"); |