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 char *ima_hash = "sha1";
39 static int __init hash_setup(char *str)
41 if (strncmp(str, "md5", 3) == 0)
45 __setup("ima_hash=", hash_setup);
48 * ima_rdwr_violation_check
50 * Only invalidate the PCR for measured files:
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.
57 static void ima_rdwr_violation_check(struct file *file)
59 struct dentry *dentry = file->f_path.dentry;
60 struct inode *inode = dentry->d_inode;
61 fmode_t mode = file->f_mode;
63 bool send_tomtou = false, send_writers = false;
67 if (!S_ISREG(inode->i_mode) || !ima_initialized)
70 mutex_lock(&inode->i_mutex); /* file metadata: permissions, xattr */
72 if (mode & FMODE_WRITE) {
73 if (atomic_read(&inode->i_readcount) && IS_IMA(inode))
78 must_measure = ima_must_measure(inode, MAY_READ, FILE_CHECK);
82 if (atomic_read(&inode->i_writecount) > 0)
85 mutex_unlock(&inode->i_mutex);
87 if (!send_tomtou && !send_writers)
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;
95 ima_add_violation(inode, pathname,
96 "invalid_pcr", "ToMToU");
98 ima_add_violation(inode, pathname,
99 "invalid_pcr", "open_writers");
103 static void ima_check_last_writer(struct integrity_iint_cache *iint,
104 struct inode *inode, struct file *file)
106 fmode_t mode = file->f_mode;
108 if (!(mode & FMODE_WRITE))
111 mutex_lock(&inode->i_mutex);
112 if (atomic_read(&inode->i_writecount) == 1 &&
113 iint->version != inode->i_version) {
114 iint->flags &= ~IMA_DONE_MASK;
115 if (iint->flags & IMA_APPRAISE)
116 ima_update_xattr(iint, file);
118 mutex_unlock(&inode->i_mutex);
122 * ima_file_free - called on __fput()
123 * @file: pointer to file structure being freed
125 * Flag files that changed, based on i_version
127 void ima_file_free(struct file *file)
129 struct inode *inode = file->f_dentry->d_inode;
130 struct integrity_iint_cache *iint;
132 if (!iint_initialized || !S_ISREG(inode->i_mode))
135 iint = integrity_iint_find(inode);
139 ima_check_last_writer(iint, inode, file);
142 static int process_measurement(struct file *file, const char *filename,
143 int mask, int function)
145 struct inode *inode = file->f_dentry->d_inode;
146 struct integrity_iint_cache *iint;
147 char *pathbuf = NULL;
148 const char *pathname = NULL;
149 int rc = -ENOMEM, action, must_appraise;
151 if (!ima_initialized || !S_ISREG(inode->i_mode))
154 /* Determine if in appraise/audit/measurement policy,
155 * returns IMA_MEASURE, IMA_APPRAISE, IMA_AUDIT bitmask. */
156 action = ima_get_action(inode, mask, function);
160 must_appraise = action & IMA_APPRAISE;
162 mutex_lock(&inode->i_mutex);
164 iint = integrity_inode_get(inode);
168 /* Determine if already appraised/measured based on bitmask
169 * (IMA_MEASURE, IMA_MEASURED, IMA_APPRAISE, IMA_APPRAISED,
170 * IMA_AUDIT, IMA_AUDITED) */
171 iint->flags |= action;
172 action &= IMA_DO_MASK;
173 action &= ~((iint->flags & IMA_DONE_MASK) >> 1);
175 /* Nothing to do, just return existing appraised status */
177 if (iint->flags & IMA_APPRAISED)
178 rc = iint->ima_status;
182 rc = ima_collect_measurement(iint, file);
186 if (function != BPRM_CHECK)
187 pathname = ima_d_path(&file->f_path, &pathbuf);
192 if (action & IMA_MEASURE)
193 ima_store_measurement(iint, file, pathname);
194 if (action & IMA_APPRAISE)
195 rc = ima_appraise_measurement(iint, file, pathname);
196 if (action & IMA_AUDIT)
197 ima_audit_measurement(iint, pathname);
200 if ((mask & MAY_WRITE) && (iint->flags & IMA_DIGSIG))
203 mutex_unlock(&inode->i_mutex);
204 if ((rc && must_appraise) && (ima_appraise & IMA_APPRAISE_ENFORCE))
210 * ima_file_mmap - based on policy, collect/store measurement.
211 * @file: pointer to the file to be measured (May be NULL)
212 * @prot: contains the protection that will be applied by the kernel.
214 * Measure files being mmapped executable based on the ima_must_measure()
217 * On success return 0. On integrity appraisal error, assuming the file
218 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
220 int ima_file_mmap(struct file *file, unsigned long prot)
222 if (file && (prot & PROT_EXEC))
223 return process_measurement(file, file->f_dentry->d_name.name,
224 MAY_EXEC, MMAP_CHECK);
229 * ima_bprm_check - based on policy, collect/store measurement.
230 * @bprm: contains the linux_binprm structure
232 * The OS protects against an executable file, already open for write,
233 * from being executed in deny_write_access() and an executable file,
234 * already open for execute, from being modified in get_write_access().
235 * So we can be certain that what we verify and measure here is actually
236 * what is being executed.
238 * On success return 0. On integrity appraisal error, assuming the file
239 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
241 int ima_bprm_check(struct linux_binprm *bprm)
243 return process_measurement(bprm->file,
244 (strcmp(bprm->filename, bprm->interp) == 0) ?
245 bprm->filename : bprm->interp,
246 MAY_EXEC, BPRM_CHECK);
250 * ima_path_check - based on policy, collect/store measurement.
251 * @file: pointer to the file to be measured
252 * @mask: contains MAY_READ, MAY_WRITE or MAY_EXECUTE
254 * Measure files based on the ima_must_measure() policy decision.
256 * On success return 0. On integrity appraisal error, assuming the file
257 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
259 int ima_file_check(struct file *file, int mask)
261 ima_rdwr_violation_check(file);
262 return process_measurement(file, file->f_dentry->d_name.name,
263 mask & (MAY_READ | MAY_WRITE | MAY_EXEC),
266 EXPORT_SYMBOL_GPL(ima_file_check);
269 * ima_module_check - based on policy, collect/store/appraise measurement.
270 * @file: pointer to the file to be measured/appraised
272 * Measure/appraise kernel modules based on policy.
274 * On success return 0. On integrity appraisal error, assuming the file
275 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
277 int ima_module_check(struct file *file)
280 return -EACCES; /* INTEGRITY_UNKNOWN */
281 return process_measurement(file, file->f_dentry->d_name.name,
282 MAY_EXEC, MODULE_CHECK);
285 static int __init init_ima(void)
295 late_initcall(init_ima); /* Start IMA after the TPM is available */
297 MODULE_DESCRIPTION("Integrity Measurement Architecture");
298 MODULE_LICENSE("GPL");