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authorDmitry Kasatkin <dmitry.kasatkin@nokia.com>2011-05-06 11:34:14 +0300
committerMimi Zohar <zohar@linux.vnet.ibm.com>2011-07-18 12:29:48 -0400
commit6d38ca01c0c2d6c2e46ec1984db9ada6bad6ca26 (patch)
tree6084a84cd87d18c261d62dc816d48335ce602447 /security/integrity
parent2960e6cb5f7c662b8edb6b0d2edc72095b4f5672 (diff)
downloadlinux-linaro-stable-6d38ca01c0c2d6c2e46ec1984db9ada6bad6ca26.tar.gz
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 <dmitry.kasatkin@nokia.com> Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Diffstat (limited to 'security/integrity')
-rw-r--r--security/integrity/evm/evm_main.c11
1 files 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;
}