blob: 0acd6e7aa09f9a0520e52a2eb2cae2d29fcc8c3d [file] [log] [blame]
Brad Bishop15ae2502019-06-18 21:44:24 -04001# No default! Either this or IMA_EVM_PRIVKEY/IMA_EVM_X509 have to be
2# set explicitly in a local.conf before activating ima-evm-rootfs.
3# To use the insecure (because public) example keys, use
Brad Bishop26bdd442019-08-16 17:08:17 -04004# IMA_EVM_KEY_DIR = "${INTEGRITY_BASE}/data/debug-keys"
Brad Bishop15ae2502019-06-18 21:44:24 -04005IMA_EVM_KEY_DIR ?= "IMA_EVM_KEY_DIR_NOT_SET"
6
7# Private key for IMA signing. The default is okay when
8# using the example key directory.
9IMA_EVM_PRIVKEY ?= "${IMA_EVM_KEY_DIR}/privkey_ima.pem"
10
11# Public part of certificates (used for both IMA and EVM).
12# The default is okay when using the example key directory.
13IMA_EVM_X509 ?= "${IMA_EVM_KEY_DIR}/x509_ima.der"
14
15# Root CA to be compiled into the kernel, none by default.
16# Must be the absolute path to a der-encoded x509 CA certificate
17# with a .x509 suffix. See linux-%.bbappend for details.
18#
19# ima-local-ca.x509 is what ima-gen-local-ca.sh creates.
20IMA_EVM_ROOT_CA ?= ""
21
22# Sign all regular files by default.
23IMA_EVM_ROOTFS_SIGNED ?= ". -type f"
24# Hash nothing by default.
25IMA_EVM_ROOTFS_HASHED ?= ". -depth 0 -false"
26
27# Mount these file systems (identified via their mount point) with
28# the iversion flags (needed by IMA when allowing writing).
29IMA_EVM_ROOTFS_IVERSION ?= ""
30
Andrew Geissler8b139282021-03-05 15:22:30 -060031# Avoid re-generating fstab when ima is enabled.
32WIC_CREATE_EXTRA_ARGS_append = "${@bb.utils.contains('DISTRO_FEATURES', 'ima', ' --no-fstab-update', '', d)}"
33
Brad Bishop15ae2502019-06-18 21:44:24 -040034ima_evm_sign_rootfs () {
35 cd ${IMAGE_ROOTFS}
36
37 # Beware that all operations below must also work when
38 # ima_evm_sign_rootfs was already called earlier for the same
39 # rootfs. That's because do_image might again run for various
40 # reasons (including a change of the signing keys) without also
41 # re-running do_rootfs.
42
Brad Bishop15ae2502019-06-18 21:44:24 -040043 # Fix /etc/fstab: it must include the "i_version" mount option for
44 # those file systems where writing files is allowed, otherwise
45 # these changes will not get detected at runtime.
46 #
47 # Note that "i_version" is documented in "man mount" only for ext4,
48 # whereas "iversion" is said to be filesystem-independent. In practice,
49 # there is only one MS_I_VERSION flag in the syscall and ext2/ext3/ext4
50 # all support it.
51 #
52 # coreutils translates "iversion" into MS_I_VERSION. busybox rejects
53 # "iversion" and only understands "i_version". systemd only understands
54 # "iversion". We pick "iversion" here for systemd, whereas rootflags
55 # for initramfs must use "i_version" for busybox.
56 #
57 # Deduplicates iversion in case that this gets called more than once.
58 if [ -f etc/fstab ]; then
59 perl -pi -e 's;(\S+)(\s+)(${@"|".join((d.getVar("IMA_EVM_ROOTFS_IVERSION", True) or "no-such-mount-point").split())})(\s+)(\S+)(\s+)(\S+);\1\2\3\4\5\6\7,iversion;; s/(,iversion)+/,iversion/;' etc/fstab
60 fi
61
62 # Sign file with private IMA key. EVM not supported at the moment.
63 bbnote "IMA/EVM: signing files 'find ${IMA_EVM_ROOTFS_SIGNED}' with private key '${IMA_EVM_PRIVKEY}'"
64 find ${IMA_EVM_ROOTFS_SIGNED} | xargs -d "\n" --no-run-if-empty --verbose evmctl ima_sign --key ${IMA_EVM_PRIVKEY}
65 bbnote "IMA/EVM: hashing files 'find ${IMA_EVM_ROOTFS_HASHED}'"
66 find ${IMA_EVM_ROOTFS_HASHED} | xargs -d "\n" --no-run-if-empty --verbose evmctl ima_hash
67
68 # Optionally install custom policy for loading by systemd.
69 if [ "${IMA_EVM_POLICY_SYSTEMD}" ]; then
70 install -d ./${sysconfdir}/ima
71 rm -f ./${sysconfdir}/ima/ima-policy
72 install "${IMA_EVM_POLICY_SYSTEMD}" ./${sysconfdir}/ima/ima-policy
73 fi
74}
75
76# Signing must run as late as possible in the do_rootfs task.
Andrew Geissler8b139282021-03-05 15:22:30 -060077# To guarantee that, we append it to IMAGE_PREPROCESS_COMMAND in
78# RecipePreFinalise event handler, this ensures it's the last
79# function in IMAGE_PREPROCESS_COMMAND.
80python ima_evm_sign_handler () {
81 if not e.data or 'ima' not in e.data.getVar('DISTRO_FEATURES').split():
82 return
Brad Bishop15ae2502019-06-18 21:44:24 -040083
Andrew Geissler8b139282021-03-05 15:22:30 -060084 e.data.appendVar('IMAGE_PREPROCESS_COMMAND', ' ima_evm_sign_rootfs; ')
85 e.data.appendVar('IMAGE_INSTALL', ' ima-evm-keys')
86 e.data.appendVarFlag('do_rootfs', 'depends', ' ima-evm-utils-native:do_populate_sysroot')
87}
88addhandler ima_evm_sign_handler
89ima_evm_sign_handler[eventmask] = "bb.event.RecipePreFinalise"