evm: skip replacing EVM signature with HMAC on read-only filesystem
If filesystem is mounted read-only or file is immutable, updating
xattr will fail. This is a usual case during early boot until
filesystem is remount read-write. This patch verifies conditions
to skip unnecessary attempt to calculate HMAC and set xattr.
Changes in v2:
* indention changed according to Lindent (requested by Mimi)
Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c
index 9685af3..b392fe6 100644
--- a/security/integrity/evm/evm_main.c
+++ b/security/integrity/evm/evm_main.c
@@ -162,9 +162,14 @@
(const char *)xattr_data, xattr_len,
calc.digest, sizeof(calc.digest));
if (!rc) {
- /* we probably want to replace rsa with hmac here */
- evm_update_evmxattr(dentry, xattr_name, xattr_value,
- xattr_value_len);
+ /* Replace RSA with HMAC if not mounted readonly and
+ * not immutable
+ */
+ if (!IS_RDONLY(dentry->d_inode) &&
+ !IS_IMMUTABLE(dentry->d_inode))
+ evm_update_evmxattr(dentry, xattr_name,
+ xattr_value,
+ xattr_value_len);
}
break;
default: