From b9abf0e09bfea8f08cc7f2d68998f014abba5b3b Mon Sep 17 00:00:00 2001 From: Stefan Berger Date: Fri, 28 Apr 2023 08:23:14 -0400 Subject: integrity: Update the README for IMA support Update the README describing how IMA support can be used. Signed-off-by: Stefan Berger Signed-off-by: Armin Kuster --- meta-integrity/README.md | 20 +++++++++++--------- 1 file changed, 11 insertions(+), 9 deletions(-) diff --git a/meta-integrity/README.md b/meta-integrity/README.md index 816b40d..1a37280 100644 --- a/meta-integrity/README.md +++ b/meta-integrity/README.md @@ -76,7 +76,7 @@ other layers needed. e.g.: It has some dependencies on a suitable BSP; in particular the kernel must have a recent enough IMA/EVM subsystem. The layer was tested with -Linux 3.19 and uses some features (like loading X509 certificates +Linux 6.1 and uses some features (like loading X509 certificates directly from the kernel) which were added in that release. Your mileage may vary with older kernels. @@ -89,10 +89,17 @@ Adding the layer only enables IMA (see below regarding EVM) during compilation of the Linux kernel. To also activate it when building the image, enable image signing in the local.conf like this: + DISTRO_FEATURES:append = " integrity ima" + IMAGE_CLASSES += "ima-evm-rootfs" + IMA_EVM_KEY_DIR = "${INTEGRITY_BASE}/data/debug-keys" IMA_EVM_PRIVKEY = "${IMA_EVM_KEY_DIR}/privkey_ima.pem" IMA_EVM_X509 = "${IMA_EVM_KEY_DIR}/x509_ima.der" + IMA_EVM_ROOT_CA = "${IMA_EVM_KEY_DIR}/ima-local-ca.pem" + + # The following policy enforces IMA & EVM signatures + IMA_EVM_POLICY = "${INTEGRITY_BASE}/recipes-security/ima_policy_appraise_all/files/ima_policy_appraise_all" This uses the default keys provided in the "data" directory of the layer. Because everyone has access to these private keys, such an image @@ -113,10 +120,7 @@ for that are included in the layer. This is also how the cd $IMA_EVM_KEY_DIR # In that shell, create the keys. Several options exist: - # 1. Self-signed keys. - $INTEGRITY_BASE/scripts/ima-gen-self-signed.sh - - # 2. Keys signed by a new CA. + # 1. Keys signed by a new CA. # When asked for a PEM passphrase, that will be for the root CA. # Signing images then will not require entering that passphrase, # only creating new certificates does. Most likely the default @@ -125,13 +129,11 @@ for that are included in the layer. This is also how the # $INTEGRITY_BASE/scripts/ima-gen-local-ca.sh # $INTEGRITY_BASE/scripts/ima-gen-CA-signed.sh - # 3. Keys signed by an existing CA. + # 2. Keys signed by an existing CA. # $INTEGRITY_BASE/scripts/ima-gen-CA-signed.sh exit -When using ``ima-self-signed.sh`` as described above, self-signed keys -are created. Alternatively, one can also use keys signed by a CA. The -``ima-gen-local-ca.sh`` and ``ima-gen.sh`` scripts create a root CA +The ``ima-gen-local-ca.sh`` and ``ima-gen.sh`` scripts create a root CA and sign the signing keys with it. The ``ima-evm-rootfs.bbclass`` then supports adding tha CA's public key to the kernel's system keyring by compiling it directly into the kernel. Because it is unknown whether -- cgit v1.2.3-54-g00ecf