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, enum ima_hooks func, int mask)
42 return ima_match_policy(inode, func, mask, IMA_APPRAISE);
45 static void ima_fix_xattr(struct dentry *dentry,
46 struct integrity_iint_cache *iint)
48 iint->ima_xattr.type = IMA_XATTR_DIGEST;
49 __vfs_setxattr_noperm(dentry, XATTR_NAME_IMA, (u8 *)&iint->ima_xattr,
50 sizeof iint->ima_xattr, 0);
54 * ima_appraise_measurement - appraise file measurement
56 * Call evm_verifyxattr() to verify the integrity of 'security.ima'.
57 * Assuming success, compare the xattr hash with the collected measurement.
59 * Return 0 on success, error code otherwise
61 int ima_appraise_measurement(struct integrity_iint_cache *iint,
62 struct file *file, const unsigned char *filename)
64 struct dentry *dentry = file->f_dentry;
65 struct inode *inode = dentry->d_inode;
66 struct evm_ima_xattr_data xattr_value;
67 enum integrity_status status = INTEGRITY_UNKNOWN;
68 const char *op = "appraise_data";
69 char *cause = "unknown";
74 if (!inode->i_op->getxattr)
75 return INTEGRITY_UNKNOWN;
77 if (iint->flags & IMA_APPRAISED)
78 return iint->ima_status;
80 rc = inode->i_op->getxattr(dentry, XATTR_NAME_IMA, (u8 *)&xattr_value,
83 if (rc && rc != -ENODATA)
86 cause = "missing-hash";
88 (inode->i_size == 0) ? INTEGRITY_PASS : INTEGRITY_NOLABEL;
92 status = evm_verifyxattr(dentry, XATTR_NAME_IMA, (u8 *)&xattr_value,
94 if ((status != INTEGRITY_PASS) && (status != INTEGRITY_UNKNOWN)) {
95 if ((status == INTEGRITY_NOLABEL)
96 || (status == INTEGRITY_NOXATTRS))
97 cause = "missing-HMAC";
98 else if (status == INTEGRITY_FAIL)
99 cause = "invalid-HMAC";
103 rc = memcmp(xattr_value.digest, iint->ima_xattr.digest,
106 status = INTEGRITY_FAIL;
107 cause = "invalid-hash";
108 print_hex_dump_bytes("security.ima: ", DUMP_PREFIX_NONE,
109 &xattr_value, sizeof xattr_value);
110 print_hex_dump_bytes("collected: ", DUMP_PREFIX_NONE,
111 (u8 *)&iint->ima_xattr,
112 sizeof iint->ima_xattr);
115 status = INTEGRITY_PASS;
116 iint->flags |= IMA_APPRAISED;
118 if (status != INTEGRITY_PASS) {
119 if (ima_appraise & IMA_APPRAISE_FIX) {
120 ima_fix_xattr(dentry, iint);
121 status = INTEGRITY_PASS;
123 integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, filename,
126 iint->ima_status = status;
131 * ima_update_xattr - update 'security.ima' hash value
133 void ima_update_xattr(struct integrity_iint_cache *iint, struct file *file)
135 struct dentry *dentry = file->f_dentry;
138 rc = ima_collect_measurement(iint, file);
141 ima_fix_xattr(dentry, iint);
145 * ima_inode_post_setattr - reflect file metadata changes
146 * @dentry: pointer to the affected dentry
148 * Changes to a dentry's metadata might result in needing to appraise.
150 * This function is called from notify_change(), which expects the caller
151 * to lock the inode's i_mutex.
153 void ima_inode_post_setattr(struct dentry *dentry)
155 struct inode *inode = dentry->d_inode;
156 struct integrity_iint_cache *iint;
157 int must_appraise, rc;
159 if (!ima_initialized || !ima_appraise || !S_ISREG(inode->i_mode)
160 || !inode->i_op->removexattr)
163 must_appraise = ima_must_appraise(inode, MAY_ACCESS, POST_SETATTR);
164 iint = integrity_iint_find(inode);
167 iint->flags |= IMA_APPRAISE;
169 iint->flags &= ~(IMA_APPRAISE | IMA_APPRAISED);
172 rc = inode->i_op->removexattr(dentry, XATTR_NAME_IMA);
177 * ima_protect_xattr - protect 'security.ima'
179 * Ensure that not just anyone can modify or remove 'security.ima'.
181 static int ima_protect_xattr(struct dentry *dentry, const char *xattr_name,
182 const void *xattr_value, size_t xattr_value_len)
184 if (strcmp(xattr_name, XATTR_NAME_IMA) == 0) {
185 if (!capable(CAP_SYS_ADMIN))
192 static void ima_reset_appraise_flags(struct inode *inode)
194 struct integrity_iint_cache *iint;
196 if (!ima_initialized || !ima_appraise || !S_ISREG(inode->i_mode))
199 iint = integrity_iint_find(inode);
203 iint->flags &= ~(IMA_COLLECTED | IMA_APPRAISED | IMA_MEASURED);
207 int ima_inode_setxattr(struct dentry *dentry, const char *xattr_name,
208 const void *xattr_value, size_t xattr_value_len)
212 result = ima_protect_xattr(dentry, xattr_name, xattr_value,
215 ima_reset_appraise_flags(dentry->d_inode);
221 int ima_inode_removexattr(struct dentry *dentry, const char *xattr_name)
225 result = ima_protect_xattr(dentry, xattr_name, NULL, 0);
227 ima_reset_appraise_flags(dentry->d_inode);