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, "fix", 3) == 0)
26 ima_appraise = IMA_APPRAISE_FIX;
30 __setup("ima_appraise=", default_appraise_setup);
33 * ima_must_appraise - set appraise flag
35 * Return 1 to appraise
37 int ima_must_appraise(struct inode *inode, int mask, enum ima_hooks func)
42 return ima_match_policy(inode, func, mask, IMA_APPRAISE);
45 static int ima_fix_xattr(struct dentry *dentry,
46 struct integrity_iint_cache *iint)
48 iint->ima_xattr.type = IMA_XATTR_DIGEST;
49 return __vfs_setxattr_noperm(dentry, XATTR_NAME_IMA,
50 (u8 *)&iint->ima_xattr,
51 sizeof(iint->ima_xattr), 0);
54 /* Return specific func appraised cached result */
55 enum integrity_status ima_get_cache_status(struct integrity_iint_cache *iint,
60 return iint->ima_mmap_status;
62 return iint->ima_bprm_status;
64 return iint->ima_module_status;
67 return iint->ima_file_status;
71 static void ima_set_cache_status(struct integrity_iint_cache *iint,
72 int func, enum integrity_status status)
76 iint->ima_mmap_status = status;
79 iint->ima_bprm_status = status;
82 iint->ima_module_status = status;
86 iint->ima_file_status = status;
91 static void ima_cache_flags(struct integrity_iint_cache *iint, int func)
95 iint->flags |= (IMA_MMAP_APPRAISED | IMA_APPRAISED);
98 iint->flags |= (IMA_BPRM_APPRAISED | IMA_APPRAISED);
101 iint->flags |= (IMA_MODULE_APPRAISED | IMA_APPRAISED);
105 iint->flags |= (IMA_FILE_APPRAISED | IMA_APPRAISED);
111 * ima_appraise_measurement - appraise file measurement
113 * Call evm_verifyxattr() to verify the integrity of 'security.ima'.
114 * Assuming success, compare the xattr hash with the collected measurement.
116 * Return 0 on success, error code otherwise
118 int ima_appraise_measurement(int func, struct integrity_iint_cache *iint,
119 struct file *file, const unsigned char *filename)
121 struct dentry *dentry = file->f_dentry;
122 struct inode *inode = dentry->d_inode;
123 struct evm_ima_xattr_data *xattr_value = NULL;
124 enum integrity_status status = INTEGRITY_UNKNOWN;
125 const char *op = "appraise_data";
126 char *cause = "unknown";
131 if (!inode->i_op->getxattr)
132 return INTEGRITY_UNKNOWN;
134 rc = vfs_getxattr_alloc(dentry, XATTR_NAME_IMA, (char **)&xattr_value,
137 if (rc && rc != -ENODATA)
140 cause = "missing-hash";
142 (inode->i_size == 0) ? INTEGRITY_PASS : INTEGRITY_NOLABEL;
146 status = evm_verifyxattr(dentry, XATTR_NAME_IMA, xattr_value, rc, iint);
147 if ((status != INTEGRITY_PASS) && (status != INTEGRITY_UNKNOWN)) {
148 if ((status == INTEGRITY_NOLABEL)
149 || (status == INTEGRITY_NOXATTRS))
150 cause = "missing-HMAC";
151 else if (status == INTEGRITY_FAIL)
152 cause = "invalid-HMAC";
155 switch (xattr_value->type) {
156 case IMA_XATTR_DIGEST:
157 if (iint->flags & IMA_DIGSIG_REQUIRED) {
158 cause = "IMA signature required";
159 status = INTEGRITY_FAIL;
162 rc = memcmp(xattr_value->digest, iint->ima_xattr.digest,
165 cause = "invalid-hash";
166 status = INTEGRITY_FAIL;
169 status = INTEGRITY_PASS;
171 case EVM_IMA_XATTR_DIGSIG:
172 iint->flags |= IMA_DIGSIG;
173 rc = integrity_digsig_verify(INTEGRITY_KEYRING_IMA,
174 xattr_value->digest, rc - 1,
175 iint->ima_xattr.digest,
177 if (rc == -EOPNOTSUPP) {
178 status = INTEGRITY_UNKNOWN;
180 cause = "invalid-signature";
181 status = INTEGRITY_FAIL;
183 status = INTEGRITY_PASS;
187 status = INTEGRITY_UNKNOWN;
188 cause = "unknown-ima-data";
193 if (status != INTEGRITY_PASS) {
194 if ((ima_appraise & IMA_APPRAISE_FIX) &&
196 xattr_value->type != EVM_IMA_XATTR_DIGSIG)) {
197 if (!ima_fix_xattr(dentry, iint))
198 status = INTEGRITY_PASS;
200 integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, filename,
203 ima_cache_flags(iint, func);
205 ima_set_cache_status(iint, func, status);
211 * ima_update_xattr - update 'security.ima' hash value
213 void ima_update_xattr(struct integrity_iint_cache *iint, struct file *file)
215 struct dentry *dentry = file->f_dentry;
218 /* do not collect and update hash for digital signatures */
219 if (iint->flags & IMA_DIGSIG)
222 rc = ima_collect_measurement(iint, file);
226 ima_fix_xattr(dentry, iint);
230 * ima_inode_post_setattr - reflect file metadata changes
231 * @dentry: pointer to the affected dentry
233 * Changes to a dentry's metadata might result in needing to appraise.
235 * This function is called from notify_change(), which expects the caller
236 * to lock the inode's i_mutex.
238 void ima_inode_post_setattr(struct dentry *dentry)
240 struct inode *inode = dentry->d_inode;
241 struct integrity_iint_cache *iint;
242 int must_appraise, rc;
244 if (!ima_initialized || !ima_appraise || !S_ISREG(inode->i_mode)
245 || !inode->i_op->removexattr)
248 must_appraise = ima_must_appraise(inode, MAY_ACCESS, POST_SETATTR);
249 iint = integrity_iint_find(inode);
251 iint->flags &= ~(IMA_APPRAISE | IMA_APPRAISED |
252 IMA_APPRAISE_SUBMASK | IMA_APPRAISED_SUBMASK |
255 iint->flags |= IMA_APPRAISE;
258 rc = inode->i_op->removexattr(dentry, XATTR_NAME_IMA);
263 * ima_protect_xattr - protect 'security.ima'
265 * Ensure that not just anyone can modify or remove 'security.ima'.
267 static int ima_protect_xattr(struct dentry *dentry, const char *xattr_name,
268 const void *xattr_value, size_t xattr_value_len)
270 if (strcmp(xattr_name, XATTR_NAME_IMA) == 0) {
271 if (!capable(CAP_SYS_ADMIN))
278 static void ima_reset_appraise_flags(struct inode *inode)
280 struct integrity_iint_cache *iint;
282 if (!ima_initialized || !ima_appraise || !S_ISREG(inode->i_mode))
285 iint = integrity_iint_find(inode);
289 iint->flags &= ~IMA_DONE_MASK;
293 int ima_inode_setxattr(struct dentry *dentry, const char *xattr_name,
294 const void *xattr_value, size_t xattr_value_len)
298 result = ima_protect_xattr(dentry, xattr_name, xattr_value,
301 ima_reset_appraise_flags(dentry->d_inode);
307 int ima_inode_removexattr(struct dentry *dentry, const char *xattr_name)
311 result = ima_protect_xattr(dentry, xattr_name, NULL, 0);
313 ima_reset_appraise_flags(dentry->d_inode);