[01/11] evm: Execute evm_inode_init_security() only when the HMAC key is loaded
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Message ID 20200618160133.937-1-roberto.sassu@huawei.com
State New
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  • [01/11] evm: Execute evm_inode_init_security() only when the HMAC key is loaded
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Commit Message

Roberto Sassu June 18, 2020, 4:01 p.m. UTC
evm_inode_init_security() requires the HMAC key to calculate the HMAC on
initial xattrs provided by LSMs. Unfortunately, with the evm_key_loaded()
check, the function continues even if the HMAC key is not loaded
(evm_key_loaded() returns true also if EVM has been initialized only with a
public key). If the HMAC key is not loaded, evm_inode_init_security()
returns an error later when it calls evm_init_hmac().

Thus, this patch replaces the evm_key_loaded() check with a check of the
EVM_INIT_HMAC flag in evm_initialized, so that evm_inode_init_security()
returns 0 instead of an error.

Cc: stable@vger.kernel.org # 4.5.x
Fixes: 26ddabfe96b ("evm: enable EVM when X509 certificate is loaded")
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
 security/integrity/evm/evm_main.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

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diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c
index 0d36259b690d..744c105b48d1 100644
--- a/security/integrity/evm/evm_main.c
+++ b/security/integrity/evm/evm_main.c
@@ -521,7 +521,8 @@  int evm_inode_init_security(struct inode *inode,
 	struct evm_xattr *xattr_data;
 	int rc;
-	if (!evm_key_loaded() || !evm_protected_xattr(lsm_xattr->name))
+	if (!(evm_initialized & EVM_INIT_HMAC) ||
+	    !evm_protected_xattr(lsm_xattr->name))
 		return 0;
 	xattr_data = kzalloc(sizeof(*xattr_data), GFP_NOFS);