1 // SPDX-License-Identifier: GPL-2.0-only
3 * Copyright (C) 2008 IBM Corporation
5 * Author: Mimi Zohar <zohar@us.ibm.com>
8 * Implements must_appraise_or_measure, collect_measurement,
9 * appraise_measurement, store_measurement and store_template.
11 #include <linux/slab.h>
12 #include <linux/file.h>
14 #include <linux/xattr.h>
15 #include <linux/evm.h>
16 #include <linux/iversion.h>
21 * ima_free_template_entry - free an existing template entry
23 void ima_free_template_entry(struct ima_template_entry *entry)
27 for (i = 0; i < entry->template_desc->num_fields; i++)
28 kfree(entry->template_data[i].data);
34 * ima_alloc_init_template - create and initialize a new template entry
36 int ima_alloc_init_template(struct ima_event_data *event_data,
37 struct ima_template_entry **entry)
39 struct ima_template_desc *template_desc = ima_template_desc_current();
42 *entry = kzalloc(sizeof(**entry) + template_desc->num_fields *
43 sizeof(struct ima_field_data), GFP_NOFS);
47 (*entry)->template_desc = template_desc;
48 for (i = 0; i < template_desc->num_fields; i++) {
49 const struct ima_template_field *field =
50 template_desc->fields[i];
53 result = field->field_init(event_data,
54 &((*entry)->template_data[i]));
58 len = (*entry)->template_data[i].len;
59 (*entry)->template_data_len += sizeof(len);
60 (*entry)->template_data_len += len;
64 ima_free_template_entry(*entry);
70 * ima_store_template - store ima template measurements
72 * Calculate the hash of a template entry, add the template entry
73 * to an ordered list of measurement entries maintained inside the kernel,
74 * and also update the aggregate integrity value (maintained inside the
75 * configured TPM PCR) over the hashes of the current list of measurement
78 * Applications retrieve the current kernel-held measurement list through
79 * the securityfs entries in /sys/kernel/security/ima. The signed aggregate
80 * TPM PCR (called quote) can be retrieved using a TPM user space library
81 * and is used to validate the measurement list.
83 * Returns 0 on success, error code otherwise
85 int ima_store_template(struct ima_template_entry *entry,
86 int violation, struct inode *inode,
87 const unsigned char *filename, int pcr)
89 static const char op[] = "add_template_measure";
90 static const char audit_cause[] = "hashing_error";
91 char *template_name = entry->template_desc->name;
94 struct ima_digest_data hdr;
95 char digest[TPM_DIGEST_SIZE];
99 int num_fields = entry->template_desc->num_fields;
101 /* this function uses default algo */
102 hash.hdr.algo = HASH_ALGO_SHA1;
103 result = ima_calc_field_array_hash(&entry->template_data[0],
104 entry->template_desc,
105 num_fields, &hash.hdr);
107 integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode,
109 audit_cause, result, 0);
112 memcpy(entry->digest, hash.hdr.digest, hash.hdr.length);
115 result = ima_add_template_entry(entry, violation, op, inode, filename);
120 * ima_add_violation - add violation to measurement list.
122 * Violations are flagged in the measurement list with zero hash values.
123 * By extending the PCR with 0xFF's instead of with zeroes, the PCR
124 * value is invalidated.
126 void ima_add_violation(struct file *file, const unsigned char *filename,
127 struct integrity_iint_cache *iint,
128 const char *op, const char *cause)
130 struct ima_template_entry *entry;
131 struct inode *inode = file_inode(file);
132 struct ima_event_data event_data = {iint, file, filename, NULL, 0,
137 /* can overflow, only indicator */
138 atomic_long_inc(&ima_htable.violations);
140 result = ima_alloc_init_template(&event_data, &entry);
145 result = ima_store_template(entry, violation, inode,
146 filename, CONFIG_IMA_MEASURE_PCR_IDX);
148 ima_free_template_entry(entry);
150 integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, filename,
151 op, cause, result, 0);
155 * ima_get_action - appraise & measure decision based on policy.
156 * @inode: pointer to inode to measure
157 * @cred: pointer to credentials structure to validate
158 * @secid: secid of the task being validated
159 * @mask: contains the permission mask (MAY_READ, MAY_WRITE, MAY_EXEC,
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 | CREDS_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, const struct cred *cred, u32 secid,
175 int mask, enum ima_hooks func, int *pcr)
177 int flags = IMA_MEASURE | IMA_AUDIT | IMA_APPRAISE | IMA_HASH;
179 flags &= ima_policy_flag;
181 return ima_match_policy(inode, cred, secid, func, mask, flags, pcr);
185 * ima_collect_measurement - collect file measurement
187 * Calculate the file hash, if it doesn't already exist,
188 * storing the measurement and i_version in the iint.
190 * Must be called with iint->mutex held.
192 * Return 0 on success, error code otherwise
194 int ima_collect_measurement(struct integrity_iint_cache *iint,
195 struct file *file, void *buf, loff_t size,
198 const char *audit_cause = "failed";
199 struct inode *inode = file_inode(file);
200 const char *filename = file->f_path.dentry->d_name.name;
206 struct ima_digest_data hdr;
207 char digest[IMA_MAX_DIGEST_SIZE];
210 if (iint->flags & IMA_COLLECTED)
214 * Dectecting file change is based on i_version. On filesystems
215 * which do not support i_version, support is limited to an initial
216 * measurement/appraisal/audit.
218 i_version = inode_query_iversion(inode);
219 hash.hdr.algo = algo;
221 /* Initialize hash digest to 0's in case of failure */
222 memset(&hash.digest, 0, sizeof(hash.digest));
225 result = ima_calc_buffer_hash(buf, size, &hash.hdr);
227 result = ima_calc_file_hash(file, &hash.hdr);
229 if (result && result != -EBADF && result != -EINVAL)
232 length = sizeof(hash.hdr) + hash.hdr.length;
233 tmpbuf = krealloc(iint->ima_hash, length, GFP_NOFS);
239 iint->ima_hash = tmpbuf;
240 memcpy(iint->ima_hash, &hash, length);
241 iint->version = i_version;
243 /* Possibly temporary failure due to type of read (eg. O_DIRECT) */
245 iint->flags |= IMA_COLLECTED;
248 if (file->f_flags & O_DIRECT)
249 audit_cause = "failed(directio)";
251 integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode,
252 filename, "collect_data", audit_cause,
259 * ima_store_measurement - store file measurement
261 * Create an "ima" template and then store the template by calling
262 * ima_store_template.
264 * We only get here if the inode has not already been measured,
265 * but the measurement could already exist:
266 * - multiple copies of the same file on either the same or
267 * different filesystems.
268 * - the inode was previously flushed as well as the iint info,
269 * containing the hashing info.
271 * Must be called with iint->mutex held.
273 void ima_store_measurement(struct integrity_iint_cache *iint,
274 struct file *file, const unsigned char *filename,
275 struct evm_ima_xattr_data *xattr_value,
276 int xattr_len, int pcr)
278 static const char op[] = "add_template_measure";
279 static const char audit_cause[] = "ENOMEM";
280 int result = -ENOMEM;
281 struct inode *inode = file_inode(file);
282 struct ima_template_entry *entry;
283 struct ima_event_data event_data = {iint, file, filename, xattr_value,
287 if (iint->measured_pcrs & (0x1 << pcr))
290 result = ima_alloc_init_template(&event_data, &entry);
292 integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, filename,
293 op, audit_cause, result, 0);
297 result = ima_store_template(entry, violation, inode, filename, pcr);
298 if ((!result || result == -EEXIST) && !(file->f_flags & O_DIRECT)) {
299 iint->flags |= IMA_MEASURED;
300 iint->measured_pcrs |= (0x1 << pcr);
303 ima_free_template_entry(entry);
306 void ima_audit_measurement(struct integrity_iint_cache *iint,
307 const unsigned char *filename)
309 struct audit_buffer *ab;
311 const char *algo_name = hash_algo_name[iint->ima_hash->algo];
314 if (iint->flags & IMA_AUDITED)
317 hash = kzalloc((iint->ima_hash->length * 2) + 1, GFP_KERNEL);
321 for (i = 0; i < iint->ima_hash->length; i++)
322 hex_byte_pack(hash + (i * 2), iint->ima_hash->digest[i]);
325 ab = audit_log_start(audit_context(), GFP_KERNEL,
326 AUDIT_INTEGRITY_RULE);
330 audit_log_format(ab, "file=");
331 audit_log_untrustedstring(ab, filename);
332 audit_log_format(ab, " hash=\"%s:%s\"", algo_name, hash);
334 audit_log_task_info(ab);
337 iint->flags |= IMA_AUDITED;
344 * ima_d_path - return a pointer to the full pathname
346 * Attempt to return a pointer to the full pathname for use in the
347 * IMA measurement list, IMA audit records, and auditing logs.
349 * On failure, return a pointer to a copy of the filename, not dname.
350 * Returning a pointer to dname, could result in using the pointer
351 * after the memory has been freed.
353 const char *ima_d_path(const struct path *path, char **pathbuf, char *namebuf)
355 char *pathname = NULL;
357 *pathbuf = __getname();
359 pathname = d_absolute_path(path, *pathbuf, PATH_MAX);
360 if (IS_ERR(pathname)) {
368 strlcpy(namebuf, path->dentry->d_name.name, NAME_MAX);