2 * Copyright (C) 2011 IBM Corporation
5 * Mimi Zohar <zohar@us.ibm.com>
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation, version 2 of the License.
11 #include <linux/module.h>
12 #include <linux/file.h>
14 #include <linux/xattr.h>
15 #include <linux/magic.h>
16 #include <linux/ima.h>
17 #include <linux/evm.h>
18 #include <crypto/hash_info.h>
22 static int __init default_appraise_setup(char *str)
24 if (strncmp(str, "off", 3) == 0)
26 else if (strncmp(str, "log", 3) == 0)
27 ima_appraise = IMA_APPRAISE_LOG;
28 else if (strncmp(str, "fix", 3) == 0)
29 ima_appraise = IMA_APPRAISE_FIX;
33 __setup("ima_appraise=", default_appraise_setup);
36 * ima_must_appraise - set appraise flag
38 * Return 1 to appraise
40 int ima_must_appraise(struct inode *inode, int mask, enum ima_hooks func)
45 return ima_match_policy(inode, func, mask, IMA_APPRAISE);
48 static int ima_fix_xattr(struct dentry *dentry,
49 struct integrity_iint_cache *iint)
52 u8 algo = iint->ima_hash->algo;
54 if (algo <= HASH_ALGO_SHA1) {
56 iint->ima_hash->xattr.sha1.type = IMA_XATTR_DIGEST;
59 iint->ima_hash->xattr.ng.type = IMA_XATTR_DIGEST_NG;
60 iint->ima_hash->xattr.ng.algo = algo;
62 rc = __vfs_setxattr_noperm(dentry, XATTR_NAME_IMA,
63 &iint->ima_hash->xattr.data[offset],
64 (sizeof(iint->ima_hash->xattr) - offset) +
65 iint->ima_hash->length, 0);
69 /* Return specific func appraised cached result */
70 enum integrity_status ima_get_cache_status(struct integrity_iint_cache *iint,
75 return iint->ima_mmap_status;
77 return iint->ima_bprm_status;
79 return iint->ima_module_status;
81 return iint->ima_firmware_status;
84 return iint->ima_file_status;
88 static void ima_set_cache_status(struct integrity_iint_cache *iint,
89 int func, enum integrity_status status)
93 iint->ima_mmap_status = status;
96 iint->ima_bprm_status = status;
99 iint->ima_module_status = status;
102 iint->ima_firmware_status = status;
106 iint->ima_file_status = status;
111 static void ima_cache_flags(struct integrity_iint_cache *iint, int func)
115 iint->flags |= (IMA_MMAP_APPRAISED | IMA_APPRAISED);
118 iint->flags |= (IMA_BPRM_APPRAISED | IMA_APPRAISED);
121 iint->flags |= (IMA_MODULE_APPRAISED | IMA_APPRAISED);
124 iint->flags |= (IMA_FIRMWARE_APPRAISED | IMA_APPRAISED);
128 iint->flags |= (IMA_FILE_APPRAISED | IMA_APPRAISED);
133 void ima_get_hash_algo(struct evm_ima_xattr_data *xattr_value, int xattr_len,
134 struct ima_digest_data *hash)
136 struct signature_v2_hdr *sig;
138 if (!xattr_value || xattr_len < 2)
141 switch (xattr_value->type) {
142 case EVM_IMA_XATTR_DIGSIG:
143 sig = (typeof(sig))xattr_value;
144 if (sig->version != 2 || xattr_len <= sizeof(*sig))
146 hash->algo = sig->hash_algo;
148 case IMA_XATTR_DIGEST_NG:
149 hash->algo = xattr_value->digest[0];
151 case IMA_XATTR_DIGEST:
152 /* this is for backward compatibility */
153 if (xattr_len == 21) {
154 unsigned int zero = 0;
155 if (!memcmp(&xattr_value->digest[16], &zero, 4))
156 hash->algo = HASH_ALGO_MD5;
158 hash->algo = HASH_ALGO_SHA1;
159 } else if (xattr_len == 17)
160 hash->algo = HASH_ALGO_MD5;
165 int ima_read_xattr(struct dentry *dentry,
166 struct evm_ima_xattr_data **xattr_value)
168 struct inode *inode = d_backing_inode(dentry);
170 if (!inode->i_op->getxattr)
173 return vfs_getxattr_alloc(dentry, XATTR_NAME_IMA, (char **)xattr_value,
178 * ima_appraise_measurement - appraise file measurement
180 * Call evm_verifyxattr() to verify the integrity of 'security.ima'.
181 * Assuming success, compare the xattr hash with the collected measurement.
183 * Return 0 on success, error code otherwise
185 int ima_appraise_measurement(int func, struct integrity_iint_cache *iint,
186 struct file *file, const unsigned char *filename,
187 struct evm_ima_xattr_data *xattr_value,
188 int xattr_len, int opened)
190 static const char op[] = "appraise_data";
191 char *cause = "unknown";
192 struct dentry *dentry = file_dentry(file);
193 struct inode *inode = d_backing_inode(dentry);
194 enum integrity_status status = INTEGRITY_UNKNOWN;
195 int rc = xattr_len, hash_start = 0;
197 if (!inode->i_op->getxattr)
198 return INTEGRITY_UNKNOWN;
201 if (rc && rc != -ENODATA)
204 cause = "missing-hash";
205 status = INTEGRITY_NOLABEL;
206 if (opened & FILE_CREATED) {
207 iint->flags |= IMA_NEW_FILE;
208 status = INTEGRITY_PASS;
213 status = evm_verifyxattr(dentry, XATTR_NAME_IMA, xattr_value, rc, iint);
214 if ((status != INTEGRITY_PASS) && (status != INTEGRITY_UNKNOWN)) {
215 if ((status == INTEGRITY_NOLABEL)
216 || (status == INTEGRITY_NOXATTRS))
217 cause = "missing-HMAC";
218 else if (status == INTEGRITY_FAIL)
219 cause = "invalid-HMAC";
222 switch (xattr_value->type) {
223 case IMA_XATTR_DIGEST_NG:
224 /* first byte contains algorithm id */
226 case IMA_XATTR_DIGEST:
227 if (iint->flags & IMA_DIGSIG_REQUIRED) {
228 cause = "IMA-signature-required";
229 status = INTEGRITY_FAIL;
232 if (xattr_len - sizeof(xattr_value->type) - hash_start >=
233 iint->ima_hash->length)
234 /* xattr length may be longer. md5 hash in previous
235 version occupied 20 bytes in xattr, instead of 16
237 rc = memcmp(&xattr_value->digest[hash_start],
238 iint->ima_hash->digest,
239 iint->ima_hash->length);
243 cause = "invalid-hash";
244 status = INTEGRITY_FAIL;
247 status = INTEGRITY_PASS;
249 case EVM_IMA_XATTR_DIGSIG:
250 iint->flags |= IMA_DIGSIG;
251 rc = integrity_digsig_verify(INTEGRITY_KEYRING_IMA,
252 (const char *)xattr_value, rc,
253 iint->ima_hash->digest,
254 iint->ima_hash->length);
255 if (rc == -EOPNOTSUPP) {
256 status = INTEGRITY_UNKNOWN;
258 cause = "invalid-signature";
259 status = INTEGRITY_FAIL;
261 status = INTEGRITY_PASS;
265 status = INTEGRITY_UNKNOWN;
266 cause = "unknown-ima-data";
271 if (status != INTEGRITY_PASS) {
272 if ((ima_appraise & IMA_APPRAISE_FIX) &&
274 xattr_value->type != EVM_IMA_XATTR_DIGSIG)) {
275 if (!ima_fix_xattr(dentry, iint))
276 status = INTEGRITY_PASS;
278 integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, filename,
281 ima_cache_flags(iint, func);
283 ima_set_cache_status(iint, func, status);
288 * ima_update_xattr - update 'security.ima' hash value
290 void ima_update_xattr(struct integrity_iint_cache *iint, struct file *file)
292 struct dentry *dentry = file_dentry(file);
295 /* do not collect and update hash for digital signatures */
296 if (iint->flags & IMA_DIGSIG)
299 rc = ima_collect_measurement(iint, file, NULL, NULL);
303 ima_fix_xattr(dentry, iint);
307 * ima_inode_post_setattr - reflect file metadata changes
308 * @dentry: pointer to the affected dentry
310 * Changes to a dentry's metadata might result in needing to appraise.
312 * This function is called from notify_change(), which expects the caller
313 * to lock the inode's i_mutex.
315 void ima_inode_post_setattr(struct dentry *dentry)
317 struct inode *inode = d_backing_inode(dentry);
318 struct integrity_iint_cache *iint;
319 int must_appraise, rc;
321 if (!(ima_policy_flag & IMA_APPRAISE) || !S_ISREG(inode->i_mode)
322 || !inode->i_op->removexattr)
325 must_appraise = ima_must_appraise(inode, MAY_ACCESS, POST_SETATTR);
326 iint = integrity_iint_find(inode);
328 iint->flags &= ~(IMA_APPRAISE | IMA_APPRAISED |
329 IMA_APPRAISE_SUBMASK | IMA_APPRAISED_SUBMASK |
332 iint->flags |= IMA_APPRAISE;
335 rc = inode->i_op->removexattr(dentry, XATTR_NAME_IMA);
340 * ima_protect_xattr - protect 'security.ima'
342 * Ensure that not just anyone can modify or remove 'security.ima'.
344 static int ima_protect_xattr(struct dentry *dentry, const char *xattr_name,
345 const void *xattr_value, size_t xattr_value_len)
347 if (strcmp(xattr_name, XATTR_NAME_IMA) == 0) {
348 if (!capable(CAP_SYS_ADMIN))
355 static void ima_reset_appraise_flags(struct inode *inode, int digsig)
357 struct integrity_iint_cache *iint;
359 if (!(ima_policy_flag & IMA_APPRAISE) || !S_ISREG(inode->i_mode))
362 iint = integrity_iint_find(inode);
366 iint->flags &= ~IMA_DONE_MASK;
368 iint->flags |= IMA_DIGSIG;
372 int ima_inode_setxattr(struct dentry *dentry, const char *xattr_name,
373 const void *xattr_value, size_t xattr_value_len)
375 const struct evm_ima_xattr_data *xvalue = xattr_value;
378 result = ima_protect_xattr(dentry, xattr_name, xattr_value,
383 if (!xattr_value_len || (xvalue->type >= IMA_XATTR_LAST))
385 digsig = (xvalue->type == EVM_IMA_XATTR_DIGSIG);
386 if (!digsig && (ima_appraise & IMA_APPRAISE_ENFORCE))
388 ima_reset_appraise_flags(d_backing_inode(dentry), digsig);
394 int ima_inode_removexattr(struct dentry *dentry, const char *xattr_name)
398 result = ima_protect_xattr(dentry, xattr_name, NULL, 0);
400 ima_reset_appraise_flags(d_backing_inode(dentry), 0);