From 492bc949e16f78fad9f274744c72bc2fd0161d84 Mon Sep 17 00:00:00 2001
From: Vitaly Kuznetsov <vkuznets@redhat.com>
Date: Fri, 9 Aug 2024 12:49:05 +0200
Subject: [PATCH] feat(fips): add support for UKIs

Kernel integrity check in FIPS module is incompatible with UKIs as neither
/boot/vmlinuz-`uname-r` nor /boot/.vmlinuz-`uname-r`.hmac are present. UKI
is placed to $ESP\EFI\Linux\<install-tag>-<uname-r>.efi and if a .hmac file
is present next to it, it is possible to do similar check.

Note, UKIs have a 'one size fits all' command line and 'boot=' is not expected
to be set. Luckily, if the UKI is systemd-stub based then we can expect
'LoaderDevicePartUUID' variable containing PARTUUID of the ESP to be set. Mount
it to /boot using the existing logic.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>

(cherry picked from commit 72684ff519be4f29c45cbb0f84759e645b0ac4be)

Resolves: RHEL-56885
---
 modules.d/01fips/fips.sh         | 51 ++++++++++++++++++++++++++++++++++++++++
 modules.d/01fips/module-setup.sh |  2 +-
 2 files changed, 52 insertions(+), 1 deletion(-)

diff --git a/modules.d/01fips/fips.sh b/modules.d/01fips/fips.sh
index 05631c8a..3889dc0c 100755
--- a/modules.d/01fips/fips.sh
+++ b/modules.d/01fips/fips.sh
@@ -14,9 +14,22 @@ else
     }
 fi
 
+# Checks if a systemd-based UKI is running and ESP UUID is set
+is_uki() {
+    [ -f /sys/firmware/efi/efivars/StubFeatures-4a67b082-0a4c-41cf-b6c7-440b29bb8c4f ] \
+        && [ -f /sys/firmware/efi/efivars/LoaderDevicePartUUID-4a67b082-0a4c-41cf-b6c7-440b29bb8c4f ]
+}
+
 mount_boot() {
     boot=$(getarg boot=)
 
+    if is_uki && [ -z "$boot" ]; then
+        # efivar file has 4 bytes header and contain UCS-2 data. Note, 'cat' is required
+        # as sys/firmware/efi/efivars/ files are 'special' and don't allow 'seeking'.
+        # shellcheck disable=SC2002
+        boot="PARTUUID=$(cat /sys/firmware/efi/efivars/LoaderDevicePartUUID-4a67b082-0a4c-41cf-b6c7-440b29bb8c4f | tail -c +5 | tr -d '\0' | tr 'A-F' 'a-f')"
+    fi
+
     if [ -n "$boot" ]; then
         if [ -d /boot ] && ismounted /boot; then
             boot_dev=
@@ -81,6 +94,41 @@ do_rhevh_check() {
     return 0
 }
 
+do_uki_check() {
+    local KVER
+    local uki_checked=0
+
+    KVER="$(uname -r)"
+    # UKI are placed in $ESP\EFI\Linux\<intall-tag>-<uname-r>.efi
+    if ! [ "$FIPS_MOUNTED_BOOT" = 1 ]; then
+        warn "Failed to mount ESP for doing UKI integrity check"
+        return 1
+    fi
+
+    for UKIpath in /boot/EFI/Linux/*-"$KVER".efi; do
+        # UKIs are installed to $ESP/EFI/Linux/<entry-token-or-machine-id>-<uname-r>.efi
+        # and in some cases (e.g. when the image is used as a template for creating new
+        # VMs) entry-token-or-machine-id can change. To make sure the running UKI is
+        # always checked, check all UKIs which match the 'uname -r' of the running kernel
+        # and fail the whole check if any of the matching UKIs are corrupted.
+
+        [ -r "$UKIpath" ] || break
+
+        local UKI="${UKIpath##*/}"
+        local UKIHMAC=."$UKI".hmac
+
+        fips_info "checking $UKIHMAC"
+        (cd /boot/EFI/Linux/ && sha512hmac -c "$UKIHMAC") || return 1
+        uki_checked=1
+    done
+
+    if [ "$uki_checked" = 0 ]; then
+        warn "Failed for find UKI for checking"
+        return 1
+    fi
+    return 0
+}
+
 nonfatal_modprobe() {
     modprobe "$1" 2>&1 > /dev/stdout \
         | while read -r line || [ -n "$line" ]; do
@@ -133,6 +181,9 @@ do_fips() {
         elif [ -e "/run/install/repo/images/pxeboot/vmlinuz" ]; then
             # This is a boot.iso with the .hmac inside the install.img
             do_rhevh_check /run/install/repo/images/pxeboot/vmlinuz || return 1
+        elif is_uki; then
+            # This is a UKI
+            do_uki_check || return 1
         else
             BOOT_IMAGE="$(getarg BOOT_IMAGE)"
 
diff --git a/modules.d/01fips/module-setup.sh b/modules.d/01fips/module-setup.sh
index 91612ff3..a090bc88 100755
--- a/modules.d/01fips/module-setup.sh
+++ b/modules.d/01fips/module-setup.sh
@@ -67,7 +67,7 @@ install() {
     inst_hook pre-udev 01 "$moddir/fips-load-crypto.sh"
     inst_script "$moddir/fips.sh" /sbin/fips.sh
 
-    inst_multiple sha512hmac rmmod insmod mount uname umount grep sed sort
+    inst_multiple sha512hmac rmmod insmod mount uname umount grep sed cut find sort cat tail tr
 
     inst_simple /etc/system-fips