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;
41 static int __init hash_setup(char *str)
43 if (strncmp(str, "md5", 3) == 0)
44 ima_hash_algo = HASH_ALGO_MD5;
47 __setup("ima_hash=", hash_setup);
50 * ima_rdwr_violation_check
52 * Only invalidate the PCR for measured files:
53 * - Opening a file for write when already open for read,
54 * results in a time of measure, time of use (ToMToU) error.
55 * - Opening a file for read when already open for write,
56 * could result in a file measurement error.
59 static void ima_rdwr_violation_check(struct file *file)
61 struct dentry *dentry = file->f_path.dentry;
62 struct inode *inode = file_inode(file);
63 fmode_t mode = file->f_mode;
65 bool send_tomtou = false, send_writers = false;
69 if (!S_ISREG(inode->i_mode) || !ima_initialized)
72 mutex_lock(&inode->i_mutex); /* file metadata: permissions, xattr */
74 if (mode & FMODE_WRITE) {
75 if (atomic_read(&inode->i_readcount) && IS_IMA(inode))
80 must_measure = ima_must_measure(inode, MAY_READ, FILE_CHECK);
84 if (atomic_read(&inode->i_writecount) > 0)
87 mutex_unlock(&inode->i_mutex);
89 if (!send_tomtou && !send_writers)
92 pathname = ima_d_path(&file->f_path, &pathbuf);
93 if (!pathname || strlen(pathname) > IMA_EVENT_NAME_LEN_MAX)
94 pathname = dentry->d_name.name;
97 ima_add_violation(inode, pathname,
98 "invalid_pcr", "ToMToU");
100 ima_add_violation(inode, pathname,
101 "invalid_pcr", "open_writers");
105 static void ima_check_last_writer(struct integrity_iint_cache *iint,
106 struct inode *inode, struct file *file)
108 fmode_t mode = file->f_mode;
110 if (!(mode & FMODE_WRITE))
113 mutex_lock(&inode->i_mutex);
114 if (atomic_read(&inode->i_writecount) == 1 &&
115 iint->version != inode->i_version) {
116 iint->flags &= ~IMA_DONE_MASK;
117 if (iint->flags & IMA_APPRAISE)
118 ima_update_xattr(iint, file);
120 mutex_unlock(&inode->i_mutex);
124 * ima_file_free - called on __fput()
125 * @file: pointer to file structure being freed
127 * Flag files that changed, based on i_version
129 void ima_file_free(struct file *file)
131 struct inode *inode = file_inode(file);
132 struct integrity_iint_cache *iint;
134 if (!iint_initialized || !S_ISREG(inode->i_mode))
137 iint = integrity_iint_find(inode);
141 ima_check_last_writer(iint, inode, file);
144 static int process_measurement(struct file *file, const char *filename,
145 int mask, int function)
147 struct inode *inode = file_inode(file);
148 struct integrity_iint_cache *iint;
149 char *pathbuf = NULL;
150 const char *pathname = NULL;
151 int rc = -ENOMEM, action, must_appraise, _func;
153 if (!ima_initialized || !S_ISREG(inode->i_mode))
156 /* Return an IMA_MEASURE, IMA_APPRAISE, IMA_AUDIT action
157 * bitmask based on the appraise/audit/measurement policy.
158 * Included is the appraise submask.
160 action = ima_get_action(inode, mask, function);
164 must_appraise = action & IMA_APPRAISE;
166 /* Is the appraise rule hook specific? */
167 _func = (action & IMA_FILE_APPRAISE) ? FILE_CHECK : function;
169 mutex_lock(&inode->i_mutex);
171 iint = integrity_inode_get(inode);
175 /* Determine if already appraised/measured based on bitmask
176 * (IMA_MEASURE, IMA_MEASURED, IMA_XXXX_APPRAISE, IMA_XXXX_APPRAISED,
177 * IMA_AUDIT, IMA_AUDITED)
179 iint->flags |= action;
180 action &= IMA_DO_MASK;
181 action &= ~((iint->flags & IMA_DONE_MASK) >> 1);
183 /* Nothing to do, just return existing appraised status */
186 rc = ima_get_cache_status(iint, _func);
190 rc = ima_collect_measurement(iint, file);
194 pathname = !filename ? ima_d_path(&file->f_path, &pathbuf) : filename;
196 pathname = (const char *)file->f_dentry->d_name.name;
198 if (action & IMA_MEASURE)
199 ima_store_measurement(iint, file, pathname);
200 if (action & IMA_APPRAISE_SUBMASK)
201 rc = ima_appraise_measurement(_func, iint, file, pathname);
202 if (action & IMA_AUDIT)
203 ima_audit_measurement(iint, pathname);
206 if ((mask & MAY_WRITE) && (iint->flags & IMA_DIGSIG))
209 mutex_unlock(&inode->i_mutex);
210 if ((rc && must_appraise) && (ima_appraise & IMA_APPRAISE_ENFORCE))
216 * ima_file_mmap - based on policy, collect/store measurement.
217 * @file: pointer to the file to be measured (May be NULL)
218 * @prot: contains the protection that will be applied by the kernel.
220 * Measure files being mmapped executable based on the ima_must_measure()
223 * On success return 0. On integrity appraisal error, assuming the file
224 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
226 int ima_file_mmap(struct file *file, unsigned long prot)
228 if (file && (prot & PROT_EXEC))
229 return process_measurement(file, NULL, MAY_EXEC, MMAP_CHECK);
234 * ima_bprm_check - based on policy, collect/store measurement.
235 * @bprm: contains the linux_binprm structure
237 * The OS protects against an executable file, already open for write,
238 * from being executed in deny_write_access() and an executable file,
239 * already open for execute, from being modified in get_write_access().
240 * So we can be certain that what we verify and measure here is actually
241 * what is being executed.
243 * On success return 0. On integrity appraisal error, assuming the file
244 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
246 int ima_bprm_check(struct linux_binprm *bprm)
248 return process_measurement(bprm->file,
249 (strcmp(bprm->filename, bprm->interp) == 0) ?
250 bprm->filename : bprm->interp,
251 MAY_EXEC, BPRM_CHECK);
255 * ima_path_check - based on policy, collect/store measurement.
256 * @file: pointer to the file to be measured
257 * @mask: contains MAY_READ, MAY_WRITE or MAY_EXECUTE
259 * Measure files based on the ima_must_measure() policy decision.
261 * On success return 0. On integrity appraisal error, assuming the file
262 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
264 int ima_file_check(struct file *file, int mask)
266 ima_rdwr_violation_check(file);
267 return process_measurement(file, NULL,
268 mask & (MAY_READ | MAY_WRITE | MAY_EXEC),
271 EXPORT_SYMBOL_GPL(ima_file_check);
274 * ima_module_check - based on policy, collect/store/appraise measurement.
275 * @file: pointer to the file to be measured/appraised
277 * Measure/appraise kernel modules based on policy.
279 * On success return 0. On integrity appraisal error, assuming the file
280 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
282 int ima_module_check(struct file *file)
285 #ifndef CONFIG_MODULE_SIG_FORCE
286 if ((ima_appraise & IMA_APPRAISE_MODULES) &&
287 (ima_appraise & IMA_APPRAISE_ENFORCE))
288 return -EACCES; /* INTEGRITY_UNKNOWN */
290 return 0; /* We rely on module signature checking */
292 return process_measurement(file, NULL, MAY_EXEC, MODULE_CHECK);
295 static int __init init_ima(void)
305 late_initcall(init_ima); /* Start IMA after the TPM is available */
307 MODULE_DESCRIPTION("Integrity Measurement Architecture");
308 MODULE_LICENSE("GPL");