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authorDmitry Kasatkin <dmitry.kasatkin@gmail.com>2014-10-01 21:43:08 +0300
committerMimi Zohar <zohar@linux.vnet.ibm.com>2014-10-07 14:32:53 -0400
commitc2baec7ffaf6a2c15e03028ed9ef82a92cc49a94 (patch)
treea08f5716f4c0dd61f451e488a557d66a748c00da /security/integrity
parentd16a8585d3715ef161cc9858b50ea5d3c8b6079b (diff)
downloadlinux-c2baec7ffaf6a2c15e03028ed9ef82a92cc49a94.tar.gz
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>
Diffstat (limited to 'security/integrity')
-rw-r--r--security/integrity/evm/evm_main.c11
1 files changed, 8 insertions, 3 deletions
diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c
index 9685af330de5..b392fe614738 100644
--- a/security/integrity/evm/evm_main.c
+++ b/security/integrity/evm/evm_main.c
@@ -162,9 +162,14 @@ static enum integrity_status evm_verify_hmac(struct dentry *dentry,
 					(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: