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/ima.h>
31 char *ima_hash = "sha1";
32 static int __init hash_setup(char *str)
34 if (strncmp(str, "md5", 3) == 0)
38 __setup("ima_hash=", hash_setup);
41 * ima_rdwr_violation_check
43 * Only invalidate the PCR for measured files:
44 * - Opening a file for write when already open for read,
45 * results in a time of measure, time of use (ToMToU) error.
46 * - Opening a file for read when already open for write,
47 * could result in a file measurement error.
50 static void ima_rdwr_violation_check(struct file *file)
52 struct dentry *dentry = file->f_path.dentry;
53 struct inode *inode = dentry->d_inode;
54 fmode_t mode = file->f_mode;
56 bool send_tomtou = false, send_writers = false;
58 if (!S_ISREG(inode->i_mode) || !ima_initialized)
61 mutex_lock(&inode->i_mutex); /* file metadata: permissions, xattr */
63 if (mode & FMODE_WRITE) {
64 if (atomic_read(&inode->i_readcount) && IS_IMA(inode))
69 rc = ima_must_measure(inode, MAY_READ, FILE_CHECK);
73 if (atomic_read(&inode->i_writecount) > 0)
76 mutex_unlock(&inode->i_mutex);
79 ima_add_violation(inode, dentry->d_name.name, "invalid_pcr",
82 ima_add_violation(inode, dentry->d_name.name, "invalid_pcr",
86 static void ima_check_last_writer(struct integrity_iint_cache *iint,
90 fmode_t mode = file->f_mode;
92 mutex_lock(&iint->mutex);
93 if (mode & FMODE_WRITE &&
94 atomic_read(&inode->i_writecount) == 1 &&
95 iint->version != inode->i_version)
96 iint->flags &= ~IMA_MEASURED;
97 mutex_unlock(&iint->mutex);
101 * ima_file_free - called on __fput()
102 * @file: pointer to file structure being freed
104 * Flag files that changed, based on i_version
106 void ima_file_free(struct file *file)
108 struct inode *inode = file->f_dentry->d_inode;
109 struct integrity_iint_cache *iint;
111 if (!iint_initialized || !S_ISREG(inode->i_mode))
114 iint = integrity_iint_find(inode);
118 ima_check_last_writer(iint, inode, file);
121 static int process_measurement(struct file *file, const unsigned char *filename,
122 int mask, int function)
124 struct inode *inode = file->f_dentry->d_inode;
125 struct integrity_iint_cache *iint;
128 if (!ima_initialized || !S_ISREG(inode->i_mode))
131 rc = ima_must_measure(inode, mask, function);
135 iint = integrity_iint_find(inode);
137 rc = integrity_inode_alloc(inode);
138 if (!rc || rc == -EEXIST)
143 mutex_lock(&iint->mutex);
145 rc = iint->flags & IMA_MEASURED ? 1 : 0;
149 rc = ima_collect_measurement(iint, file);
151 ima_store_measurement(iint, file, filename);
153 mutex_unlock(&iint->mutex);
158 * ima_file_mmap - based on policy, collect/store measurement.
159 * @file: pointer to the file to be measured (May be NULL)
160 * @prot: contains the protection that will be applied by the kernel.
162 * Measure files being mmapped executable based on the ima_must_measure()
165 * Return 0 on success, an error code on failure.
166 * (Based on the results of appraise_measurement().)
168 int ima_file_mmap(struct file *file, unsigned long prot)
174 if (prot & PROT_EXEC)
175 rc = process_measurement(file, file->f_dentry->d_name.name,
176 MAY_EXEC, FILE_MMAP);
181 * ima_bprm_check - based on policy, collect/store measurement.
182 * @bprm: contains the linux_binprm structure
184 * The OS protects against an executable file, already open for write,
185 * from being executed in deny_write_access() and an executable file,
186 * already open for execute, from being modified in get_write_access().
187 * So we can be certain that what we verify and measure here is actually
188 * what is being executed.
190 * Return 0 on success, an error code on failure.
191 * (Based on the results of appraise_measurement().)
193 int ima_bprm_check(struct linux_binprm *bprm)
197 rc = process_measurement(bprm->file, bprm->filename,
198 MAY_EXEC, BPRM_CHECK);
203 * ima_path_check - based on policy, collect/store measurement.
204 * @file: pointer to the file to be measured
205 * @mask: contains MAY_READ, MAY_WRITE or MAY_EXECUTE
207 * Measure files based on the ima_must_measure() policy decision.
209 * Always return 0 and audit dentry_open failures.
210 * (Return code will be based upon measurement appraisal.)
212 int ima_file_check(struct file *file, int mask)
216 ima_rdwr_violation_check(file);
217 rc = process_measurement(file, file->f_dentry->d_name.name,
218 mask & (MAY_READ | MAY_WRITE | MAY_EXEC),
222 EXPORT_SYMBOL_GPL(ima_file_check);
224 static int __init init_ima(void)
233 static void __exit cleanup_ima(void)
238 late_initcall(init_ima); /* Start IMA after the TPM is available */
240 MODULE_DESCRIPTION("Integrity Measurement Architecture");
241 MODULE_LICENSE("GPL");