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>
21 static int __init default_appraise_setup(char *str)
23 if (strncmp(str, "off", 3) == 0)
25 else if (strncmp(str, "log", 3) == 0)
26 ima_appraise = IMA_APPRAISE_LOG;
27 else if (strncmp(str, "fix", 3) == 0)
28 ima_appraise = IMA_APPRAISE_FIX;
32 __setup("ima_appraise=", default_appraise_setup);
35 * ima_must_appraise - set appraise flag
37 * Return 1 to appraise
39 int ima_must_appraise(struct inode *inode, int mask, enum ima_hooks func)
44 return ima_match_policy(inode, func, mask, IMA_APPRAISE, NULL);
47 static int ima_fix_xattr(struct dentry *dentry,
48 struct integrity_iint_cache *iint)
51 u8 algo = iint->ima_hash->algo;
53 if (algo <= HASH_ALGO_SHA1) {
55 iint->ima_hash->xattr.sha1.type = IMA_XATTR_DIGEST;
58 iint->ima_hash->xattr.ng.type = IMA_XATTR_DIGEST_NG;
59 iint->ima_hash->xattr.ng.algo = algo;
61 rc = __vfs_setxattr_noperm(dentry, XATTR_NAME_IMA,
62 &iint->ima_hash->xattr.data[offset],
63 (sizeof(iint->ima_hash->xattr) - offset) +
64 iint->ima_hash->length, 0);
68 /* Return specific func appraised cached result */
69 enum integrity_status ima_get_cache_status(struct integrity_iint_cache *iint,
74 return iint->ima_mmap_status;
76 return iint->ima_bprm_status;
79 return iint->ima_file_status;
80 case MODULE_CHECK ... MAX_CHECK - 1:
82 return iint->ima_read_status;
86 static void ima_set_cache_status(struct integrity_iint_cache *iint,
88 enum integrity_status status)
92 iint->ima_mmap_status = status;
95 iint->ima_bprm_status = status;
99 iint->ima_file_status = status;
101 case MODULE_CHECK ... MAX_CHECK - 1:
103 iint->ima_read_status = status;
108 static void ima_cache_flags(struct integrity_iint_cache *iint,
113 iint->flags |= (IMA_MMAP_APPRAISED | IMA_APPRAISED);
116 iint->flags |= (IMA_BPRM_APPRAISED | IMA_APPRAISED);
120 iint->flags |= (IMA_FILE_APPRAISED | IMA_APPRAISED);
122 case MODULE_CHECK ... MAX_CHECK - 1:
124 iint->flags |= (IMA_READ_APPRAISED | IMA_APPRAISED);
129 enum hash_algo ima_get_hash_algo(struct evm_ima_xattr_data *xattr_value,
132 struct signature_v2_hdr *sig;
134 if (!xattr_value || xattr_len < 2)
135 /* return default hash algo */
136 return ima_hash_algo;
138 switch (xattr_value->type) {
139 case EVM_IMA_XATTR_DIGSIG:
140 sig = (typeof(sig))xattr_value;
141 if (sig->version != 2 || xattr_len <= sizeof(*sig))
142 return ima_hash_algo;
143 return sig->hash_algo;
145 case IMA_XATTR_DIGEST_NG:
146 return xattr_value->digest[0];
148 case IMA_XATTR_DIGEST:
149 /* this is for backward compatibility */
150 if (xattr_len == 21) {
151 unsigned int zero = 0;
152 if (!memcmp(&xattr_value->digest[16], &zero, 4))
153 return HASH_ALGO_MD5;
155 return HASH_ALGO_SHA1;
156 } else if (xattr_len == 17)
157 return HASH_ALGO_MD5;
161 /* return default hash algo */
162 return ima_hash_algo;
165 int ima_read_xattr(struct dentry *dentry,
166 struct evm_ima_xattr_data **xattr_value)
170 ret = vfs_getxattr_alloc(dentry, XATTR_NAME_IMA, (char **)xattr_value,
172 if (ret == -EOPNOTSUPP)
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(enum ima_hooks func,
186 struct integrity_iint_cache *iint,
187 struct file *file, const unsigned char *filename,
188 struct evm_ima_xattr_data *xattr_value,
189 int xattr_len, int opened)
191 static const char op[] = "appraise_data";
192 char *cause = "unknown";
193 struct dentry *dentry = file->f_path.dentry;
194 struct inode *inode = d_backing_inode(dentry);
195 enum integrity_status status = INTEGRITY_UNKNOWN;
196 int rc = xattr_len, hash_start = 0;
198 if (!(inode->i_opflags & IOP_XATTR))
199 return INTEGRITY_UNKNOWN;
202 if (rc && rc != -ENODATA)
205 cause = "missing-hash";
206 status = INTEGRITY_NOLABEL;
207 if (opened & FILE_CREATED) {
208 iint->flags |= IMA_NEW_FILE;
209 status = INTEGRITY_PASS;
214 status = evm_verifyxattr(dentry, XATTR_NAME_IMA, xattr_value, rc, iint);
215 if ((status != INTEGRITY_PASS) && (status != INTEGRITY_UNKNOWN)) {
216 if ((status == INTEGRITY_NOLABEL)
217 || (status == INTEGRITY_NOXATTRS))
218 cause = "missing-HMAC";
219 else if (status == INTEGRITY_FAIL)
220 cause = "invalid-HMAC";
223 switch (xattr_value->type) {
224 case IMA_XATTR_DIGEST_NG:
225 /* first byte contains algorithm id */
227 case IMA_XATTR_DIGEST:
228 if (iint->flags & IMA_DIGSIG_REQUIRED) {
229 cause = "IMA-signature-required";
230 status = INTEGRITY_FAIL;
233 if (xattr_len - sizeof(xattr_value->type) - hash_start >=
234 iint->ima_hash->length)
235 /* xattr length may be longer. md5 hash in previous
236 version occupied 20 bytes in xattr, instead of 16
238 rc = memcmp(&xattr_value->digest[hash_start],
239 iint->ima_hash->digest,
240 iint->ima_hash->length);
244 cause = "invalid-hash";
245 status = INTEGRITY_FAIL;
248 status = INTEGRITY_PASS;
250 case EVM_IMA_XATTR_DIGSIG:
251 iint->flags |= IMA_DIGSIG;
252 rc = integrity_digsig_verify(INTEGRITY_KEYRING_IMA,
253 (const char *)xattr_value, rc,
254 iint->ima_hash->digest,
255 iint->ima_hash->length);
256 if (rc == -EOPNOTSUPP) {
257 status = INTEGRITY_UNKNOWN;
259 cause = "invalid-signature";
260 status = INTEGRITY_FAIL;
262 status = INTEGRITY_PASS;
266 status = INTEGRITY_UNKNOWN;
267 cause = "unknown-ima-data";
272 if (status != INTEGRITY_PASS) {
273 if ((ima_appraise & IMA_APPRAISE_FIX) &&
275 xattr_value->type != EVM_IMA_XATTR_DIGSIG)) {
276 if (!ima_fix_xattr(dentry, iint))
277 status = INTEGRITY_PASS;
278 } else if ((inode->i_size == 0) &&
279 (iint->flags & IMA_NEW_FILE) &&
281 xattr_value->type == EVM_IMA_XATTR_DIGSIG)) {
282 status = INTEGRITY_PASS;
284 integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, filename,
287 ima_cache_flags(iint, func);
289 ima_set_cache_status(iint, func, status);
294 * ima_update_xattr - update 'security.ima' hash value
296 void ima_update_xattr(struct integrity_iint_cache *iint, struct file *file)
298 struct dentry *dentry = file->f_path.dentry;
301 /* do not collect and update hash for digital signatures */
302 if (iint->flags & IMA_DIGSIG)
305 rc = ima_collect_measurement(iint, file, NULL, 0, ima_hash_algo);
309 ima_fix_xattr(dentry, iint);
313 * ima_inode_post_setattr - reflect file metadata changes
314 * @dentry: pointer to the affected dentry
316 * Changes to a dentry's metadata might result in needing to appraise.
318 * This function is called from notify_change(), which expects the caller
319 * to lock the inode's i_mutex.
321 void ima_inode_post_setattr(struct dentry *dentry)
323 struct inode *inode = d_backing_inode(dentry);
324 struct integrity_iint_cache *iint;
327 if (!(ima_policy_flag & IMA_APPRAISE) || !S_ISREG(inode->i_mode)
328 || !(inode->i_opflags & IOP_XATTR))
331 must_appraise = ima_must_appraise(inode, MAY_ACCESS, POST_SETATTR);
332 iint = integrity_iint_find(inode);
334 iint->flags &= ~(IMA_APPRAISE | IMA_APPRAISED |
335 IMA_APPRAISE_SUBMASK | IMA_APPRAISED_SUBMASK |
336 IMA_ACTION_RULE_FLAGS);
338 iint->flags |= IMA_APPRAISE;
341 __vfs_removexattr(dentry, XATTR_NAME_IMA);
345 * ima_protect_xattr - protect 'security.ima'
347 * Ensure that not just anyone can modify or remove 'security.ima'.
349 static int ima_protect_xattr(struct dentry *dentry, const char *xattr_name,
350 const void *xattr_value, size_t xattr_value_len)
352 if (strcmp(xattr_name, XATTR_NAME_IMA) == 0) {
353 if (!capable(CAP_SYS_ADMIN))
360 static void ima_reset_appraise_flags(struct inode *inode, int digsig)
362 struct integrity_iint_cache *iint;
364 if (!(ima_policy_flag & IMA_APPRAISE) || !S_ISREG(inode->i_mode))
367 iint = integrity_iint_find(inode);
371 iint->flags &= ~IMA_DONE_MASK;
372 iint->measured_pcrs = 0;
374 iint->flags |= IMA_DIGSIG;
378 int ima_inode_setxattr(struct dentry *dentry, const char *xattr_name,
379 const void *xattr_value, size_t xattr_value_len)
381 const struct evm_ima_xattr_data *xvalue = xattr_value;
384 result = ima_protect_xattr(dentry, xattr_name, xattr_value,
389 if (!xattr_value_len || (xvalue->type >= IMA_XATTR_LAST))
391 digsig = (xvalue->type == EVM_IMA_XATTR_DIGSIG);
392 if (!digsig && (ima_appraise & IMA_APPRAISE_ENFORCE))
394 ima_reset_appraise_flags(d_backing_inode(dentry), digsig);
400 int ima_inode_removexattr(struct dentry *dentry, const char *xattr_name)
404 result = ima_protect_xattr(dentry, xattr_name, NULL, 0);
406 ima_reset_appraise_flags(d_backing_inode(dentry), 0);