2 * Copyright (C) 2005,2006,2007,2008 IBM Corporation
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>
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
16 * implements the IMA hooks: ima_bprm_check, ima_file_mmap,
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>
24 #include <linux/slab.h>
25 #include <linux/xattr.h>
26 #include <linux/ima.h>
32 #ifdef CONFIG_IMA_APPRAISE
33 int ima_appraise
= IMA_APPRAISE_ENFORCE
;
38 int ima_hash_algo
= HASH_ALGO_SHA1
;
39 static int hash_setup_done
;
41 static int __init
hash_setup(char *str
)
43 struct ima_template_desc
*template_desc
= ima_template_desc_current();
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
;
57 for (i
= 0; i
< HASH_ALGO__LAST
; i
++) {
58 if (strcmp(str
, hash_algo_name
[i
]) == 0) {
67 __setup("ima_hash=", hash_setup
);
70 * ima_rdwr_violation_check
72 * Only invalidate the PCR for measured files:
73 * - Opening a file for write when already open for read,
74 * results in a time of measure, time of use (ToMToU) error.
75 * - Opening a file for read when already open for write,
76 * could result in a file measurement error.
79 static void ima_rdwr_violation_check(struct file
*file
,
80 struct integrity_iint_cache
*iint
,
83 const char **pathname
)
85 struct inode
*inode
= file_inode(file
);
86 fmode_t mode
= file
->f_mode
;
87 bool send_tomtou
= false, send_writers
= false;
89 if (mode
& FMODE_WRITE
) {
90 if (atomic_read(&inode
->i_readcount
) && IS_IMA(inode
)) {
92 iint
= integrity_iint_find(inode
);
93 /* IMA_MEASURE is set from reader side */
94 if (iint
&& (iint
->flags
& IMA_MEASURE
))
98 if ((atomic_read(&inode
->i_writecount
) > 0) && must_measure
)
102 if (!send_tomtou
&& !send_writers
)
105 *pathname
= ima_d_path(&file
->f_path
, pathbuf
);
108 ima_add_violation(file
, *pathname
, iint
,
109 "invalid_pcr", "ToMToU");
111 ima_add_violation(file
, *pathname
, iint
,
112 "invalid_pcr", "open_writers");
115 static void ima_check_last_writer(struct integrity_iint_cache
*iint
,
116 struct inode
*inode
, struct file
*file
)
118 fmode_t mode
= file
->f_mode
;
120 if (!(mode
& FMODE_WRITE
))
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 iint
->measured_pcrs
= 0;
129 if (iint
->flags
& IMA_APPRAISE
)
130 ima_update_xattr(iint
, file
);
137 * ima_file_free - called on __fput()
138 * @file: pointer to file structure being freed
140 * Flag files that changed, based on i_version
142 void ima_file_free(struct file
*file
)
144 struct inode
*inode
= file_inode(file
);
145 struct integrity_iint_cache
*iint
;
147 if (!ima_policy_flag
|| !S_ISREG(inode
->i_mode
))
150 iint
= integrity_iint_find(inode
);
154 ima_check_last_writer(iint
, inode
, file
);
157 static int process_measurement(struct file
*file
, char *buf
, loff_t size
,
158 int mask
, enum ima_hooks func
, int opened
)
160 struct inode
*inode
= file_inode(file
);
161 struct integrity_iint_cache
*iint
= NULL
;
162 struct ima_template_desc
*template_desc
;
163 char *pathbuf
= NULL
;
164 const char *pathname
= NULL
;
165 int rc
= -ENOMEM
, action
, must_appraise
;
166 int pcr
= CONFIG_IMA_MEASURE_PCR_IDX
;
167 struct evm_ima_xattr_data
*xattr_value
= NULL
;
169 bool violation_check
;
170 enum hash_algo hash_algo
;
172 if (!ima_policy_flag
|| !S_ISREG(inode
->i_mode
))
175 /* Return an IMA_MEASURE, IMA_APPRAISE, IMA_AUDIT action
176 * bitmask based on the appraise/audit/measurement policy.
177 * Included is the appraise submask.
179 action
= ima_get_action(inode
, mask
, func
, &pcr
);
180 violation_check
= ((func
== FILE_CHECK
|| func
== MMAP_CHECK
) &&
181 (ima_policy_flag
& IMA_MEASURE
));
182 if (!action
&& !violation_check
)
185 must_appraise
= action
& IMA_APPRAISE
;
187 /* Is the appraise rule hook specific? */
188 if (action
& IMA_FILE_APPRAISE
)
194 iint
= integrity_inode_get(inode
);
199 if (violation_check
) {
200 ima_rdwr_violation_check(file
, iint
, action
& IMA_MEASURE
,
201 &pathbuf
, &pathname
);
208 /* Determine if already appraised/measured based on bitmask
209 * (IMA_MEASURE, IMA_MEASURED, IMA_XXXX_APPRAISE, IMA_XXXX_APPRAISED,
210 * IMA_AUDIT, IMA_AUDITED)
212 iint
->flags
|= action
;
213 action
&= IMA_DO_MASK
;
214 action
&= ~((iint
->flags
& (IMA_DONE_MASK
^ IMA_MEASURED
)) >> 1);
216 /* If target pcr is already measured, unset IMA_MEASURE action */
217 if ((action
& IMA_MEASURE
) && (iint
->measured_pcrs
& (0x1 << pcr
)))
218 action
^= IMA_MEASURE
;
220 /* Nothing to do, just return existing appraised status */
223 rc
= ima_get_cache_status(iint
, func
);
227 template_desc
= ima_template_desc_current();
228 if ((action
& IMA_APPRAISE_SUBMASK
) ||
229 strcmp(template_desc
->name
, IMA_TEMPLATE_IMA_NAME
) != 0)
230 /* read 'security.ima' */
231 xattr_len
= ima_read_xattr(file
->f_path
.dentry
, &xattr_value
);
233 hash_algo
= ima_get_hash_algo(xattr_value
, xattr_len
);
235 rc
= ima_collect_measurement(iint
, file
, buf
, size
, hash_algo
);
237 if (file
->f_flags
& O_DIRECT
)
238 rc
= (iint
->flags
& IMA_PERMIT_DIRECTIO
) ? 0 : -EACCES
;
242 if (!pathname
) /* ima_rdwr_violation possibly pre-fetched */
243 pathname
= ima_d_path(&file
->f_path
, &pathbuf
);
245 if (action
& IMA_MEASURE
)
246 ima_store_measurement(iint
, file
, pathname
,
247 xattr_value
, xattr_len
, pcr
);
248 if (action
& IMA_APPRAISE_SUBMASK
)
249 rc
= ima_appraise_measurement(func
, iint
, file
, pathname
,
250 xattr_value
, xattr_len
, opened
);
251 if (action
& IMA_AUDIT
)
252 ima_audit_measurement(iint
, pathname
);
255 if ((mask
& MAY_WRITE
) && (iint
->flags
& IMA_DIGSIG
) &&
256 !(iint
->flags
& IMA_NEW_FILE
))
264 if ((rc
&& must_appraise
) && (ima_appraise
& IMA_APPRAISE_ENFORCE
))
270 * ima_file_mmap - based on policy, collect/store measurement.
271 * @file: pointer to the file to be measured (May be NULL)
272 * @prot: contains the protection that will be applied by the kernel.
274 * Measure files being mmapped executable based on the ima_must_measure()
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.
280 int ima_file_mmap(struct file
*file
, unsigned long prot
)
282 if (file
&& (prot
& PROT_EXEC
))
283 return process_measurement(file
, NULL
, 0, MAY_EXEC
,
289 * ima_bprm_check - based on policy, collect/store measurement.
290 * @bprm: contains the linux_binprm structure
292 * The OS protects against an executable file, already open for write,
293 * from being executed in deny_write_access() and an executable file,
294 * already open for execute, from being modified in get_write_access().
295 * So we can be certain that what we verify and measure here is actually
296 * what is being executed.
298 * On success return 0. On integrity appraisal error, assuming the file
299 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
301 int ima_bprm_check(struct linux_binprm
*bprm
)
303 return process_measurement(bprm
->file
, NULL
, 0, MAY_EXEC
,
308 * ima_path_check - based on policy, collect/store measurement.
309 * @file: pointer to the file to be measured
310 * @mask: contains MAY_READ, MAY_WRITE or MAY_EXECUTE
312 * Measure files based on the ima_must_measure() policy decision.
314 * On success return 0. On integrity appraisal error, assuming the file
315 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
317 int ima_file_check(struct file
*file
, int mask
, int opened
)
319 return process_measurement(file
, NULL
, 0,
320 mask
& (MAY_READ
| MAY_WRITE
| MAY_EXEC
),
323 EXPORT_SYMBOL_GPL(ima_file_check
);
326 * ima_post_path_mknod - mark as a new inode
327 * @dentry: newly created dentry
329 * Mark files created via the mknodat syscall as new, so that the
330 * file data can be written later.
332 void ima_post_path_mknod(struct dentry
*dentry
)
334 struct integrity_iint_cache
*iint
;
335 struct inode
*inode
= dentry
->d_inode
;
338 must_appraise
= ima_must_appraise(inode
, MAY_ACCESS
, FILE_CHECK
);
342 iint
= integrity_inode_get(inode
);
344 iint
->flags
|= IMA_NEW_FILE
;
348 * ima_read_file - pre-measure/appraise hook decision based on policy
349 * @file: pointer to the file to be measured/appraised/audit
350 * @read_id: caller identifier
352 * Permit reading a file based on policy. The policy rules are written
353 * in terms of the policy identifier. Appraising the integrity of
354 * a file requires a file descriptor.
356 * For permission return 0, otherwise return -EACCES.
358 int ima_read_file(struct file
*file
, enum kernel_read_file_id read_id
)
360 if (!file
&& read_id
== READING_MODULE
) {
361 #ifndef CONFIG_MODULE_SIG_FORCE
362 if ((ima_appraise
& IMA_APPRAISE_MODULES
) &&
363 (ima_appraise
& IMA_APPRAISE_ENFORCE
))
364 return -EACCES
; /* INTEGRITY_UNKNOWN */
366 return 0; /* We rely on module signature checking */
371 static int read_idmap
[READING_MAX_ID
] = {
372 [READING_FIRMWARE
] = FIRMWARE_CHECK
,
373 [READING_MODULE
] = MODULE_CHECK
,
374 [READING_KEXEC_IMAGE
] = KEXEC_KERNEL_CHECK
,
375 [READING_KEXEC_INITRAMFS
] = KEXEC_INITRAMFS_CHECK
,
376 [READING_POLICY
] = POLICY_CHECK
380 * ima_post_read_file - in memory collect/appraise/audit measurement
381 * @file: pointer to the file to be measured/appraised/audit
382 * @buf: pointer to in memory file contents
383 * @size: size of in memory file contents
384 * @read_id: caller identifier
386 * Measure/appraise/audit in memory file based on policy. Policy rules
387 * are written in terms of a policy identifier.
389 * On success return 0. On integrity appraisal error, assuming the file
390 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
392 int ima_post_read_file(struct file
*file
, void *buf
, loff_t size
,
393 enum kernel_read_file_id read_id
)
397 if (!file
&& read_id
== READING_FIRMWARE
) {
398 if ((ima_appraise
& IMA_APPRAISE_FIRMWARE
) &&
399 (ima_appraise
& IMA_APPRAISE_ENFORCE
))
400 return -EACCES
; /* INTEGRITY_UNKNOWN */
404 if (!file
&& read_id
== READING_MODULE
) /* MODULE_SIG_FORCE enabled */
407 if (!file
|| !buf
|| size
== 0) { /* should never happen */
408 if (ima_appraise
& IMA_APPRAISE_ENFORCE
)
413 func
= read_idmap
[read_id
] ?: FILE_CHECK
;
414 return process_measurement(file
, buf
, size
, MAY_READ
, func
, 0);
417 static int __init
init_ima(void)
421 hash_setup(CONFIG_IMA_DEFAULT_HASH
);
425 ima_update_policy_flag();
430 late_initcall(init_ima
); /* Start IMA after the TPM is available */
432 MODULE_DESCRIPTION("Integrity Measurement Architecture");
433 MODULE_LICENSE("GPL");