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>
27 #include <crypto/hash_info.h>
33 #ifdef CONFIG_IMA_APPRAISE
34 int ima_appraise = IMA_APPRAISE_ENFORCE;
39 int ima_hash_algo = HASH_ALGO_SHA1;
40 static int hash_setup_done;
42 static int __init hash_setup(char *str)
44 struct ima_template_desc *template_desc = ima_template_desc_current();
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;
58 for (i = 0; i < HASH_ALGO__LAST; i++) {
59 if (strcmp(str, hash_algo_name[i]) == 0) {
68 __setup("ima_hash=", hash_setup);
71 * ima_rdwr_violation_check
73 * Only invalidate the PCR for measured files:
74 * - Opening a file for write when already open for read,
75 * results in a time of measure, time of use (ToMToU) error.
76 * - Opening a file for read when already open for write,
77 * could result in a file measurement error.
80 static void ima_rdwr_violation_check(struct file *file)
82 struct inode *inode = file_inode(file);
83 fmode_t mode = file->f_mode;
84 bool send_tomtou = false, send_writers = false;
88 if (!S_ISREG(inode->i_mode) || !ima_initialized)
91 mutex_lock(&inode->i_mutex); /* file metadata: permissions, xattr */
93 if (mode & FMODE_WRITE) {
94 if (atomic_read(&inode->i_readcount) && IS_IMA(inode))
97 if ((atomic_read(&inode->i_writecount) > 0) &&
98 ima_must_measure(inode, MAY_READ, FILE_CHECK))
102 mutex_unlock(&inode->i_mutex);
104 if (!send_tomtou && !send_writers)
107 pathname = ima_d_path(&file->f_path, &pathbuf);
110 ima_add_violation(file, pathname, "invalid_pcr", "ToMToU");
112 ima_add_violation(file, pathname,
113 "invalid_pcr", "open_writers");
117 static void ima_check_last_writer(struct integrity_iint_cache *iint,
118 struct inode *inode, struct file *file)
120 fmode_t mode = file->f_mode;
122 if (!(mode & FMODE_WRITE))
125 mutex_lock(&inode->i_mutex);
126 if (atomic_read(&inode->i_writecount) == 1 &&
127 iint->version != inode->i_version) {
128 iint->flags &= ~IMA_DONE_MASK;
129 if (iint->flags & IMA_APPRAISE)
130 ima_update_xattr(iint, file);
132 mutex_unlock(&inode->i_mutex);
136 * ima_file_free - called on __fput()
137 * @file: pointer to file structure being freed
139 * Flag files that changed, based on i_version
141 void ima_file_free(struct file *file)
143 struct inode *inode = file_inode(file);
144 struct integrity_iint_cache *iint;
146 if (!iint_initialized || !S_ISREG(inode->i_mode))
149 iint = integrity_iint_find(inode);
153 ima_check_last_writer(iint, inode, file);
156 static int process_measurement(struct file *file, const char *filename,
157 int mask, int function)
159 struct inode *inode = file_inode(file);
160 struct integrity_iint_cache *iint;
161 struct ima_template_desc *template_desc = ima_template_desc_current();
162 char *pathbuf = NULL;
163 const char *pathname = NULL;
164 int rc = -ENOMEM, action, must_appraise, _func;
165 struct evm_ima_xattr_data *xattr_value = NULL, **xattr_ptr = NULL;
168 if (!ima_initialized || !S_ISREG(inode->i_mode))
171 /* Return an IMA_MEASURE, IMA_APPRAISE, IMA_AUDIT action
172 * bitmask based on the appraise/audit/measurement policy.
173 * Included is the appraise submask.
175 action = ima_get_action(inode, mask, function);
179 must_appraise = action & IMA_APPRAISE;
181 /* Is the appraise rule hook specific? */
182 _func = (action & IMA_FILE_APPRAISE) ? FILE_CHECK : function;
184 mutex_lock(&inode->i_mutex);
186 iint = integrity_inode_get(inode);
190 /* Determine if already appraised/measured based on bitmask
191 * (IMA_MEASURE, IMA_MEASURED, IMA_XXXX_APPRAISE, IMA_XXXX_APPRAISED,
192 * IMA_AUDIT, IMA_AUDITED)
194 iint->flags |= action;
195 action &= IMA_DO_MASK;
196 action &= ~((iint->flags & IMA_DONE_MASK) >> 1);
198 /* Nothing to do, just return existing appraised status */
201 rc = ima_get_cache_status(iint, _func);
205 if (strcmp(template_desc->name, IMA_TEMPLATE_IMA_NAME) == 0) {
206 if (action & IMA_APPRAISE_SUBMASK)
207 xattr_ptr = &xattr_value;
209 xattr_ptr = &xattr_value;
211 rc = ima_collect_measurement(iint, file, xattr_ptr, &xattr_len);
213 if (file->f_flags & O_DIRECT)
214 rc = (iint->flags & IMA_PERMIT_DIRECTIO) ? 0 : -EACCES;
218 pathname = filename ?: ima_d_path(&file->f_path, &pathbuf);
220 if (action & IMA_MEASURE)
221 ima_store_measurement(iint, file, pathname,
222 xattr_value, xattr_len);
223 if (action & IMA_APPRAISE_SUBMASK)
224 rc = ima_appraise_measurement(_func, iint, file, pathname,
225 xattr_value, xattr_len);
226 if (action & IMA_AUDIT)
227 ima_audit_measurement(iint, pathname);
230 if ((mask & MAY_WRITE) && (iint->flags & IMA_DIGSIG))
233 mutex_unlock(&inode->i_mutex);
235 if ((rc && must_appraise) && (ima_appraise & IMA_APPRAISE_ENFORCE))
241 * ima_file_mmap - based on policy, collect/store measurement.
242 * @file: pointer to the file to be measured (May be NULL)
243 * @prot: contains the protection that will be applied by the kernel.
245 * Measure files being mmapped executable based on the ima_must_measure()
248 * On success return 0. On integrity appraisal error, assuming the file
249 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
251 int ima_file_mmap(struct file *file, unsigned long prot)
253 if (file && (prot & PROT_EXEC))
254 return process_measurement(file, NULL, MAY_EXEC, MMAP_CHECK);
259 * ima_bprm_check - based on policy, collect/store measurement.
260 * @bprm: contains the linux_binprm structure
262 * The OS protects against an executable file, already open for write,
263 * from being executed in deny_write_access() and an executable file,
264 * already open for execute, from being modified in get_write_access().
265 * So we can be certain that what we verify and measure here is actually
266 * what is being executed.
268 * On success return 0. On integrity appraisal error, assuming the file
269 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
271 int ima_bprm_check(struct linux_binprm *bprm)
273 return process_measurement(bprm->file,
274 (strcmp(bprm->filename, bprm->interp) == 0) ?
275 bprm->filename : bprm->interp,
276 MAY_EXEC, BPRM_CHECK);
280 * ima_path_check - based on policy, collect/store measurement.
281 * @file: pointer to the file to be measured
282 * @mask: contains MAY_READ, MAY_WRITE or MAY_EXECUTE
284 * Measure files based on the ima_must_measure() policy decision.
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.
289 int ima_file_check(struct file *file, int mask)
291 ima_rdwr_violation_check(file);
292 return process_measurement(file, NULL,
293 mask & (MAY_READ | MAY_WRITE | MAY_EXEC),
296 EXPORT_SYMBOL_GPL(ima_file_check);
299 * ima_module_check - based on policy, collect/store/appraise measurement.
300 * @file: pointer to the file to be measured/appraised
302 * Measure/appraise kernel modules based on policy.
304 * On success return 0. On integrity appraisal error, assuming the file
305 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
307 int ima_module_check(struct file *file)
310 #ifndef CONFIG_MODULE_SIG_FORCE
311 if ((ima_appraise & IMA_APPRAISE_MODULES) &&
312 (ima_appraise & IMA_APPRAISE_ENFORCE))
313 return -EACCES; /* INTEGRITY_UNKNOWN */
315 return 0; /* We rely on module signature checking */
317 return process_measurement(file, NULL, MAY_EXEC, MODULE_CHECK);
320 static int __init init_ima(void)
324 hash_setup(CONFIG_IMA_DEFAULT_HASH);
331 late_initcall(init_ima); /* Start IMA after the TPM is available */
333 MODULE_DESCRIPTION("Integrity Measurement Architecture");
334 MODULE_LICENSE("GPL");