evm: limit verifying current security.evm integrity
evm_protect_xattr unnecessarily validates the current security.evm
integrity, before updating non-evm protected extended attributes
and other file metadata. This patch limits validating the current
security.evm integrity to evm protected metadata.
Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c
index f0127e5..7d42475 100644
--- a/security/integrity/evm/evm_main.c
+++ b/security/integrity/evm/evm_main.c
@@ -159,21 +159,6 @@
EXPORT_SYMBOL_GPL(evm_verifyxattr);
/*
- * evm_protect_xattr - protect the EVM extended attribute
- *
- * Prevent security.evm from being modified or removed.
- */
-static int evm_protect_xattr(struct dentry *dentry, const char *xattr_name,
- const void *xattr_value, size_t xattr_value_len)
-{
- if (strcmp(xattr_name, XATTR_NAME_EVM) == 0) {
- if (!capable(CAP_SYS_ADMIN))
- return -EPERM;
- }
- return 0;
-}
-
-/*
* evm_verify_current_integrity - verify the dentry's metadata integrity
* @dentry: pointer to the affected dentry
*
@@ -189,6 +174,26 @@
return evm_verify_hmac(dentry, NULL, NULL, 0, NULL);
}
+/*
+ * evm_protect_xattr - protect the EVM extended attribute
+ *
+ * Prevent security.evm from being modified or removed.
+ */
+static int evm_protect_xattr(struct dentry *dentry, const char *xattr_name,
+ const void *xattr_value, size_t xattr_value_len)
+{
+ enum integrity_status evm_status;
+
+ if (strcmp(xattr_name, XATTR_NAME_EVM) == 0) {
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+ } else if (!evm_protected_xattr(xattr_name))
+ return 0;
+
+ evm_status = evm_verify_current_integrity(dentry);
+ return evm_status == INTEGRITY_PASS ? 0 : -EPERM;
+}
+
/**
* evm_inode_setxattr - protect the EVM extended attribute
* @dentry: pointer to the affected dentry
@@ -202,16 +207,8 @@
int evm_inode_setxattr(struct dentry *dentry, const char *xattr_name,
const void *xattr_value, size_t xattr_value_len)
{
-
- enum integrity_status evm_status;
- int ret;
-
- ret = evm_protect_xattr(dentry, xattr_name, xattr_value,
- xattr_value_len);
- if (ret)
- return ret;
- evm_status = evm_verify_current_integrity(dentry);
- return evm_status == INTEGRITY_PASS ? 0 : -EPERM;
+ return evm_protect_xattr(dentry, xattr_name, xattr_value,
+ xattr_value_len);
}
/**
@@ -224,14 +221,7 @@
*/
int evm_inode_removexattr(struct dentry *dentry, const char *xattr_name)
{
- enum integrity_status evm_status;
- int ret;
-
- ret = evm_protect_xattr(dentry, xattr_name, NULL, 0);
- if (ret)
- return ret;
- evm_status = evm_verify_current_integrity(dentry);
- return evm_status == INTEGRITY_PASS ? 0 : -EPERM;
+ return evm_protect_xattr(dentry, xattr_name, NULL, 0);
}
/**
@@ -286,7 +276,7 @@
unsigned int ia_valid = attr->ia_valid;
enum integrity_status evm_status;
- if (ia_valid & ~(ATTR_MODE | ATTR_UID | ATTR_GID))
+ if (!(ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID)))
return 0;
evm_status = evm_verify_current_integrity(dentry);
return evm_status == INTEGRITY_PASS ? 0 : -EPERM;