Re: [PATCH v10 09/12] ima: Implement support for module-style appended signatures
From: Mimi Zohar <zohar@linux.ibm.com>
Date: 2019-05-14 12:09:52
Also in:
keyrings, linux-crypto, linux-integrity, linux-security-module, linuxppc-dev, lkml
Hi Thiago, On Thu, 2019-04-18 at 00:51 -0300, Thiago Jung Bauermann wrote:
quoted hunk ↗ jump to hunk
@@ -326,6 +356,10 @@ int ima_appraise_measurement(enum ima_hooks func,case INTEGRITY_UNKNOWN: break; case INTEGRITY_NOXATTRS: /* No EVM protected xattrs. */ + /* It's fine not to have xattrs when using a modsig. */ + if (try_modsig) + break; + /* fall through */ case INTEGRITY_NOLABEL: /* No security.evm xattr. */ cause = "missing-HMAC"; goto out;@@ -340,6 +374,14 @@ int ima_appraise_measurement(enum ima_hooks func,rc = xattr_verify(func, iint, xattr_value, xattr_len, &status, &cause); + /* + * If we have a modsig and either no imasig or the imasig's key isn't + * known, then try verifying the modsig. + */ + if (status != INTEGRITY_PASS && try_modsig && + (!xattr_value || rc == -ENOKEY)) + rc = modsig_verify(func, modsig, &status, &cause);
EVM protects other security xattrs, not just security.ima, if they exist. As a result, evm_verifyxattr() could pass based on the other security xattrs. Mimi
+ out: /* * File signatures on some filesystems can not be properly verified.