diff options
Diffstat (limited to 'meta-integrity/README.md')
| -rw-r--r-- | meta-integrity/README.md | 36 |
1 files changed, 21 insertions, 15 deletions
diff --git a/meta-integrity/README.md b/meta-integrity/README.md index 8254b0d..c333a9f 100644 --- a/meta-integrity/README.md +++ b/meta-integrity/README.md @@ -6,7 +6,7 @@ The bbappend files for some recipes (e.g. linux-yocto) in this layer need to have 'integrity' in DISTRO_FEATURES to have effect. To enable them, add in configuration file the following line. - DISTRO_FEATURES_append = " integrity" + DISTRO_FEATURES:append = " integrity" If meta-integrity is included, but integrity is not enabled as a distro feature a warning is printed at parse time: @@ -41,7 +41,7 @@ Patches ======= For discussion or patch submission via email, use the -yocto@yoctoproject.org mailing list. When submitting patches that way, +yocto-patches@yoctoproject.org mailing list. When submitting patches that way, make sure to copy the maintainer and add a "[meta-integrity]" prefix to the subject of the mails. @@ -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. # $INTEGRITY_BASE/scripts/ima-gen-CA-signed.sh <CA.pem> <CA.priv> exit -When using ``ima-self-signed.sh`` as described above, self-signed keys -are created. Alternatively, one can also use keys signed by a CA. The -``ima-gen-local-ca.sh`` and ``ima-gen.sh`` scripts create a root CA +The ``ima-gen-local-ca.sh`` and ``ima-gen.sh`` scripts create a root CA and sign the signing keys with it. The ``ima-evm-rootfs.bbclass`` then supports adding tha CA's public key to the kernel's system keyring by compiling it directly into the kernel. Because it is unknown whether @@ -187,7 +189,7 @@ IMA policy loading became broken in systemd 2.18. The modified systemd changes. To activate policy loading via systemd, place a policy file in `/etc/ima/ima-policy`, for example with: - IMA_EVM_POLICY_SYSTEMD = "${INTEGRITY_BASE}/data/ima_policy_simple" + IMA_EVM_POLICY = "${INTEGRITY_BASE}/data/ima_policy_simple" To check that measuring works, look at `/sys/kernel/security/ima/ascii_runtime_measurements` @@ -217,12 +219,16 @@ executing the file is no longer allowed: -sh: /usr/bin/rpm: Permission denied Enabling the audit kernel subsystem may help to debug appraisal -issues. Enable it by adding the meta-security-framework layer and +issues. Enable it by adding a kernel configuration fragment and changing your local.conf: - SRC_URI_append_pn-linux-yocto = " file://audit.cfg" + SRC_URI:append:pn-linux-yocto = " file://audit.cfg" CORE_IMAGE_EXTRA_INSTALL += "auditd" -Then boot with "ima_appraise=log ima_appraise_tcb". +Then boot with "ima_appraise=log ima_appraise_tcb integrity_audit=1". +For example, for QEMU by changing variable QB_KERNEL_CMDLINE_APPEND +in your local.conf: + QB_KERNEL_CMDLINE_APPEND:remove:pn-integrity-image-minimal = "ima_policy=tcb ima_appraise=fix" + QB_KERNEL_CMDLINE_APPEND:append:pn-integrity-image-minimal = " ima_appraise=log ima_appraise_tcb integrity_audit=1" Adding auditd is not strictly necessary but helps to capture a more complete set of events in /var/log/audit/ and search in |