linux-kernel - [PATCH v2 2/3] integrity: Enforce digitalSignature usage in the ima and evm keyrings

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Message-Id: <20230522230944.180389-3-eric.snowberg@oracle.com>
Date:   Mon, 22 May 2023 19:09:43 -0400
From:   Eric Snowberg <eric.snowberg@...cle.com>
To:     jarkko@...nel.org, zohar@...ux.ibm.com, dhowells@...hat.com,
        dwmw2@...radead.org
Cc:     herbert@...dor.apana.org.au, davem@...emloft.net,
        dmitry.kasatkin@...il.com, paul@...l-moore.com, jmorris@...ei.org,
        serge@...lyn.com, jlee@...e.com, eric.snowberg@...cle.com,
        kanth.ghatraju@...cle.com, konrad.wilk@...cle.com,
        keyrings@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-crypto@...r.kernel.org, linux-integrity@...r.kernel.org,
        linux-security-module@...r.kernel.org
Subject: [PATCH v2 2/3] integrity: Enforce digitalSignature usage in the ima and evm keyrings

After being vouched for by a system keyring, only allow keys into the .ima
and .evm keyrings that have the digitalSignature usage field set.

Link: https://lore.kernel.org/all/41dffdaeb7eb7840f7e38bc691fbda836635c9f9.camel@linux.ibm.com
Suggested-by: Mimi Zohar <zohar@...ux.ibm.com>
Signed-off-by: Eric Snowberg <eric.snowberg@...cle.com>
Acked-by: Mimi Zohar <zohar@...ux.ibm.com>
---
 security/integrity/digsig.c    | 4 ++--
 security/integrity/evm/Kconfig | 3 ++-
 security/integrity/ima/Kconfig | 3 ++-
 3 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/security/integrity/digsig.c b/security/integrity/digsig.c
index 6f31ffe23c48..d0704b1597d4 100644
--- a/security/integrity/digsig.c
+++ b/security/integrity/digsig.c
@@ -34,9 +34,9 @@ static const char * const keyring_name[INTEGRITY_KEYRING_MAX] = {
 };
 
 #ifdef CONFIG_IMA_KEYRINGS_PERMIT_SIGNED_BY_BUILTIN_OR_SECONDARY
-#define restrict_link_to_ima restrict_link_by_builtin_and_secondary_trusted
+#define restrict_link_to_ima restrict_link_by_digsig_builtin_and_secondary
 #else
-#define restrict_link_to_ima restrict_link_by_builtin_trusted
+#define restrict_link_to_ima restrict_link_by_digsig_builtin
 #endif
 
 static struct key *integrity_keyring_from_id(const unsigned int id)
diff --git a/security/integrity/evm/Kconfig b/security/integrity/evm/Kconfig
index a6e19d23e700..fba9ee359bc9 100644
--- a/security/integrity/evm/Kconfig
+++ b/security/integrity/evm/Kconfig
@@ -64,7 +64,8 @@ config EVM_LOAD_X509
 
 	   This option enables X509 certificate loading from the kernel
 	   onto the '.evm' trusted keyring.  A public key can be used to
-	   verify EVM integrity starting from the 'init' process.
+	   verify EVM integrity starting from the 'init' process. The
+	   key must have digitalSignature usage set.
 
 config EVM_X509_PATH
 	string "EVM X509 certificate path"
diff --git a/security/integrity/ima/Kconfig b/security/integrity/ima/Kconfig
index 60a511c6b583..684425936c53 100644
--- a/security/integrity/ima/Kconfig
+++ b/security/integrity/ima/Kconfig
@@ -270,7 +270,8 @@ config IMA_KEYRINGS_PERMIT_SIGNED_BY_BUILTIN_OR_SECONDARY
 	help
 	  Keys may be added to the IMA or IMA blacklist keyrings, if the
 	  key is validly signed by a CA cert in the system built-in or
-	  secondary trusted keyrings.
+	  secondary trusted keyrings. The key must also have the
+	  digitalSignature usage set.
 
 	  Intermediate keys between those the kernel has compiled in and the
 	  IMA keys to be added may be added to the system secondary keyring,
-- 
2.27.0