2 * Copyright (C) 2008 IBM Corporation
4 * Author: Mimi Zohar <zohar@us.ibm.com>
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License as
8 * published by the Free Software Foundation, version 2 of the
12 * Implements must_appraise_or_measure, collect_measurement,
13 * appraise_measurement, store_measurement and store_template.
15 #include <linux/module.h>
16 #include <linux/slab.h>
17 #include <linux/file.h>
19 #include <linux/xattr.h>
20 #include <linux/evm.h>
25 * ima_free_template_entry - free an existing template entry
27 void ima_free_template_entry(struct ima_template_entry *entry)
31 for (i = 0; i < entry->template_desc->num_fields; i++)
32 kfree(entry->template_data[i].data);
38 * ima_alloc_init_template - create and initialize a new template entry
40 int ima_alloc_init_template(struct ima_event_data *event_data,
41 struct ima_template_entry **entry)
43 struct ima_template_desc *template_desc = ima_template_desc_current();
46 *entry = kzalloc(sizeof(**entry) + template_desc->num_fields *
47 sizeof(struct ima_field_data), GFP_NOFS);
51 (*entry)->template_desc = template_desc;
52 for (i = 0; i < template_desc->num_fields; i++) {
53 struct ima_template_field *field = template_desc->fields[i];
56 result = field->field_init(event_data,
57 &((*entry)->template_data[i]));
61 len = (*entry)->template_data[i].len;
62 (*entry)->template_data_len += sizeof(len);
63 (*entry)->template_data_len += len;
67 ima_free_template_entry(*entry);
73 * ima_store_template - store ima template measurements
75 * Calculate the hash of a template entry, add the template entry
76 * to an ordered list of measurement entries maintained inside the kernel,
77 * and also update the aggregate integrity value (maintained inside the
78 * configured TPM PCR) over the hashes of the current list of measurement
81 * Applications retrieve the current kernel-held measurement list through
82 * the securityfs entries in /sys/kernel/security/ima. The signed aggregate
83 * TPM PCR (called quote) can be retrieved using a TPM user space library
84 * and is used to validate the measurement list.
86 * Returns 0 on success, error code otherwise
88 int ima_store_template(struct ima_template_entry *entry,
89 int violation, struct inode *inode,
90 const unsigned char *filename, int pcr)
92 static const char op[] = "add_template_measure";
93 static const char audit_cause[] = "hashing_error";
94 char *template_name = entry->template_desc->name;
97 struct ima_digest_data hdr;
98 char digest[TPM_DIGEST_SIZE];
102 int num_fields = entry->template_desc->num_fields;
104 /* this function uses default algo */
105 hash.hdr.algo = HASH_ALGO_SHA1;
106 result = ima_calc_field_array_hash(&entry->template_data[0],
107 entry->template_desc,
108 num_fields, &hash.hdr);
110 integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode,
112 audit_cause, result, 0);
115 memcpy(entry->digest, hash.hdr.digest, hash.hdr.length);
118 result = ima_add_template_entry(entry, violation, op, inode, filename);
123 * ima_add_violation - add violation to measurement list.
125 * Violations are flagged in the measurement list with zero hash values.
126 * By extending the PCR with 0xFF's instead of with zeroes, the PCR
127 * value is invalidated.
129 void ima_add_violation(struct file *file, const unsigned char *filename,
130 struct integrity_iint_cache *iint,
131 const char *op, const char *cause)
133 struct ima_template_entry *entry;
134 struct inode *inode = file_inode(file);
135 struct ima_event_data event_data = {iint, file, filename, NULL, 0,
140 /* can overflow, only indicator */
141 atomic_long_inc(&ima_htable.violations);
143 result = ima_alloc_init_template(&event_data, &entry);
148 result = ima_store_template(entry, violation, inode,
149 filename, CONFIG_IMA_MEASURE_PCR_IDX);
151 ima_free_template_entry(entry);
153 integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, filename,
154 op, cause, result, 0);
158 * ima_get_action - appraise & measure decision based on policy.
159 * @inode: pointer to inode to measure
160 * @mask: contains the permission mask (MAY_READ, MAY_WRITE, MAY_EXECUTE)
161 * @func: caller identifier
162 * @pcr: pointer filled in if matched measure policy sets pcr=
164 * The policy is defined in terms of keypairs:
165 * subj=, obj=, type=, func=, mask=, fsmagic=
166 * subj,obj, and type: are LSM specific.
167 * func: FILE_CHECK | BPRM_CHECK | MMAP_CHECK | MODULE_CHECK
168 * mask: contains the permission mask
171 * Returns IMA_MEASURE, IMA_APPRAISE mask.
174 int ima_get_action(struct inode *inode, int mask, enum ima_hooks func, int *pcr)
176 int flags = IMA_MEASURE | IMA_AUDIT | IMA_APPRAISE;
178 flags &= ima_policy_flag;
180 return ima_match_policy(inode, func, mask, flags, pcr);
184 * ima_collect_measurement - collect file measurement
186 * Calculate the file hash, if it doesn't already exist,
187 * storing the measurement and i_version in the iint.
189 * Must be called with iint->mutex held.
191 * Return 0 on success, error code otherwise
193 int ima_collect_measurement(struct integrity_iint_cache *iint,
194 struct file *file, void *buf, loff_t size,
197 const char *audit_cause = "failed";
198 struct inode *inode = file_inode(file);
199 const char *filename = file->f_path.dentry->d_name.name;
205 struct ima_digest_data hdr;
206 char digest[IMA_MAX_DIGEST_SIZE];
209 if (iint->flags & IMA_COLLECTED)
213 * Dectecting file change is based on i_version. On filesystems
214 * which do not support i_version, support is limited to an initial
215 * measurement/appraisal/audit.
217 i_version = file_inode(file)->i_version;
218 hash.hdr.algo = algo;
220 /* Initialize hash digest to 0's in case of failure */
221 memset(&hash.digest, 0, sizeof(hash.digest));
224 result = ima_calc_buffer_hash(buf, size, &hash.hdr);
226 result = ima_calc_file_hash(file, &hash.hdr);
228 if (result && result != -EBADF && result != -EINVAL)
231 length = sizeof(hash.hdr) + hash.hdr.length;
232 tmpbuf = krealloc(iint->ima_hash, length, GFP_NOFS);
238 iint->ima_hash = tmpbuf;
239 memcpy(iint->ima_hash, &hash, length);
240 iint->version = i_version;
242 /* Possibly temporary failure due to type of read (eg. O_DIRECT) */
244 iint->flags |= IMA_COLLECTED;
247 if (file->f_flags & O_DIRECT)
248 audit_cause = "failed(directio)";
250 integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode,
251 filename, "collect_data", audit_cause,
258 * ima_store_measurement - store file measurement
260 * Create an "ima" template and then store the template by calling
261 * ima_store_template.
263 * We only get here if the inode has not already been measured,
264 * but the measurement could already exist:
265 * - multiple copies of the same file on either the same or
266 * different filesystems.
267 * - the inode was previously flushed as well as the iint info,
268 * containing the hashing info.
270 * Must be called with iint->mutex held.
272 void ima_store_measurement(struct integrity_iint_cache *iint,
273 struct file *file, const unsigned char *filename,
274 struct evm_ima_xattr_data *xattr_value,
275 int xattr_len, int pcr)
277 static const char op[] = "add_template_measure";
278 static const char audit_cause[] = "ENOMEM";
279 int result = -ENOMEM;
280 struct inode *inode = file_inode(file);
281 struct ima_template_entry *entry;
282 struct ima_event_data event_data = {iint, file, filename, xattr_value,
286 if (iint->measured_pcrs & (0x1 << pcr))
289 result = ima_alloc_init_template(&event_data, &entry);
291 integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, filename,
292 op, audit_cause, result, 0);
296 result = ima_store_template(entry, violation, inode, filename, pcr);
297 if ((!result || result == -EEXIST) && !(file->f_flags & O_DIRECT)) {
298 iint->flags |= IMA_MEASURED;
299 iint->measured_pcrs |= (0x1 << pcr);
302 ima_free_template_entry(entry);
305 void ima_audit_measurement(struct integrity_iint_cache *iint,
306 const unsigned char *filename)
308 struct audit_buffer *ab;
309 char hash[(iint->ima_hash->length * 2) + 1];
310 const char *algo_name = hash_algo_name[iint->ima_hash->algo];
311 char algo_hash[sizeof(hash) + strlen(algo_name) + 2];
314 if (iint->flags & IMA_AUDITED)
317 for (i = 0; i < iint->ima_hash->length; i++)
318 hex_byte_pack(hash + (i * 2), iint->ima_hash->digest[i]);
321 ab = audit_log_start(current->audit_context, GFP_KERNEL,
322 AUDIT_INTEGRITY_RULE);
326 audit_log_format(ab, "file=");
327 audit_log_untrustedstring(ab, filename);
328 audit_log_format(ab, " hash=");
329 snprintf(algo_hash, sizeof(algo_hash), "%s:%s", algo_name, hash);
330 audit_log_untrustedstring(ab, algo_hash);
332 audit_log_task_info(ab, current);
335 iint->flags |= IMA_AUDITED;
339 * ima_d_path - return a pointer to the full pathname
341 * Attempt to return a pointer to the full pathname for use in the
342 * IMA measurement list, IMA audit records, and auditing logs.
344 * On failure, return a pointer to a copy of the filename, not dname.
345 * Returning a pointer to dname, could result in using the pointer
346 * after the memory has been freed.
348 const char *ima_d_path(const struct path *path, char **pathbuf, char *namebuf)
350 char *pathname = NULL;
352 *pathbuf = __getname();
354 pathname = d_absolute_path(path, *pathbuf, PATH_MAX);
355 if (IS_ERR(pathname)) {
363 strlcpy(namebuf, path->dentry->d_name.name, NAME_MAX);