From 6d38ca01c0c2d6c2e46ec1984db9ada6bad6ca26 Mon Sep 17 00:00:00 2001 From: Dmitry Kasatkin Date: Fri, 6 May 2011 11:34:14 +0300 Subject: [PATCH] evm: evm_verify_hmac must not return INTEGRITY_UNKNOWN If EVM is not supported or enabled, evm_verify_hmac() returns INTEGRITY_UNKNOWN, which ima_appraise_measurement() ignores and sets the appraisal status based solely on the security.ima verification. evm_verify_hmac() also returns INTEGRITY_UNKNOWN for other failures, such as temporary failures like -ENOMEM, resulting in possible attack vectors. This patch changes the default return code for temporary/unexpected failures, like -ENOMEM, from INTEGRITY_UNKNOWN to INTEGRITY_FAIL, making evm_verify_hmac() fail safe. As a result, failures need to be re-evaluated in order to catch both temporary errors, such as the -ENOMEM, as well as errors that have been resolved in fix mode. Signed-off-by: Dmitry Kasatkin Signed-off-by: Mimi Zohar --- security/integrity/evm/evm_main.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c index 0fa8261c3655..bfe44dff61bb 100644 --- a/security/integrity/evm/evm_main.c +++ b/security/integrity/evm/evm_main.c @@ -56,13 +56,15 @@ static enum integrity_status evm_verify_hmac(struct dentry *dentry, struct evm_ima_xattr_data xattr_data; int rc; - if (iint->hmac_status != INTEGRITY_UNKNOWN) + if (iint->hmac_status == INTEGRITY_PASS) return iint->hmac_status; + /* if status is not PASS, try to check again - against -ENOMEM */ + rc = evm_calc_hmac(dentry, xattr_name, xattr_value, xattr_value_len, xattr_data.digest); if (rc < 0) - return INTEGRITY_UNKNOWN; + goto err_out; xattr_data.type = EVM_XATTR_HMAC; rc = vfs_xattr_cmp(dentry, XATTR_NAME_EVM, (u8 *)&xattr_data, @@ -77,11 +79,8 @@ err_out: case -ENODATA: /* file not labelled */ iint->hmac_status = INTEGRITY_NOLABEL; break; - case -EINVAL: - iint->hmac_status = INTEGRITY_FAIL; - break; default: - iint->hmac_status = INTEGRITY_UNKNOWN; + iint->hmac_status = INTEGRITY_FAIL; } return iint->hmac_status; } -- 2.39.5