feat(fips-crypto-policies): Make c-p follow FIPS mode automatically

modules.d/01fips-crypto-policies/fips-crypto-policies.sh

@@ -0,0 +1,52 @@
+#!/usr/bin/sh
+
+type getarg > /dev/null 2>&1 || . /lib/dracut-lib.sh
+
+if ! fipsmode=$(getarg fips) || [ "$fipsmode" = "0" ] || [ -z "$fipsmode" ]; then
+    # Do nothing if not in FIPS mode
+    exit 0
+fi
+
+policyfile=/etc/crypto-policies/config
+fipspolicyfile=/usr/share/crypto-policies/default-fips-config
+backends=/etc/crypto-policies/back-ends
+fipsbackends=/usr/share/crypto-policies/back-ends/FIPS
+
+# When in FIPS mode, check the active crypto policy by reading the
+# $root/etc/crypto-policies/config file. If it is not "FIPS", or does not start
+# with "FIPS:", automatically switch to the FIPS policy by creating
+# bind-mounts.
+
+if ! [ -r "${NEWROOT}${policyfile}" ]; then
+    # No crypto-policies configured, possibly not a system that uses
+    # crypto-policies?
+    exit 0
+fi
+
+if ! [ -f "${NEWROOT}${fipspolicyfile}" ]; then
+    # crypto-policies is too old to deal with automatic bind-mounting of the
+    # FIPS policy over the normal policy, do not attempt to do the bind-mount.
+    exit 0
+fi
+
+policy=$(cat "${NEWROOT}${policyfile}")
+
+# Remove the largest suffix pattern matching ":*" from the string (i.e., the
+# complete list of active policy modules), then check for FIPS. This is part of
+# POSIX sh (https://pubs.opengroup.org/onlinepubs/009695399/utilities/xcu_chap02.html#tag_02_06_02).
+if [ "${policy%%:*}" = "FIPS" ]; then
+    exit 0
+fi
+
+# Current crypto policy is not FIPS or FIPS-based, but the system is in FIPS
+# mode; this is an inconsistent configuration. Automatically bind-mount a FIPS
+# configuration over this.
+if ! mount -o bind,ro "${NEWROOT}${fipsbackends}" "${NEWROOT}${backends}"; then
+    warn "Failed to bind-mount FIPS policy over ${backends} (the system is in FIPS mode, but the crypto-policy is not)."
+    # If this bind-mount failed, don't attempt to do the other one to avoid
+    # a system that seems to be in FIPS crypto-policy but actually is not.
+    exit 0
+fi
+
+mount -o bind,ro "${NEWROOT}${fipspolicyfile}" "${NEWROOT}${policyfile}" \
+    || warn "Failed to bind-mount FIPS crypto-policy state file over ${policyfile} (the system is in FIPS mode, but the crypto-policy is not)."

modules.d/01fips-crypto-policies/module-setup.sh

@@ -0,0 +1,27 @@
+#!/usr/bin/bash
+
+# called by dracut
+check() {
+    # only enable on systems that use crypto-policies
+    [ -d "$dracutsysrootdir/etc/crypto-policies" ] && return 0
+
+    # include when something else depends on it or it is explicitly requested
+    return 255
+}
+
+# called by dracut
+depends() {
+    return 0
+}
+
+# called by dracut
+installkernel() {
+    return 0
+}
+
+# called by dracut
+install() {
+    inst_hook pre-pivot 01 "$moddir/fips-crypto-policies.sh"
+
+    inst_multiple mount
+}