[PATCH 6/6] selinux-policy-2.eclass: use an array when constructing commands

Avoids an unnecessary, trivially avoidable bash footgun.

Relying on word splitting is not all that robust nor desirable. Whilst
it indeed _can_ be fine when you can _guarentee_ that ALL arguments do
not contain whitespace, they add extra fragility for no real reason.

Instead of building up a command string, use the much better suited
bash arrays for constructing command arguments. This way, if we ever
have to account for arguments containing spaces, we get that for free
without having to worry about uprooting the way command arguments are
constructed, or worse potentially forgetting to do all-together and
executing a command we did not intend to execute.

Signed-off-by: Rahul Sandhu <[email protected]>
---
 eclass/selinux-policy-2.eclass | 30 ++++++++++++++----------------
 1 file changed, 14 insertions(+), 16 deletions(-)

diff --git a/eclass/selinux-policy-2.eclass b/eclass/selinux-policy-2.eclass
index 911ef39781e1..41cbfc0248a8 100644
--- a/eclass/selinux-policy-2.eclass
+++ b/eclass/selinux-policy-2.eclass
@@ -281,14 +281,11 @@ selinux-policy-2_src_install() {
 # activating the policy on the system.
 selinux-policy-2_pkg_postinst() {
 	# Set root path and don't load policy into the kernel when cross compiling
-	local root_opts=""
+	local root_opts=()
 	if [[ -n ${ROOT} ]]; then
-		root_opts="-p ${ROOT} -n"
+		root_opts=( "-p" "${ROOT}" "-n" )
 	fi
 
-	# build up the command in the case of multiple modules
-	local COMMAND
-
 	for type in targeted strict mcs mls; do
 		if use "selinux_policy_types_${type}"; then
 			if [[ "${type}" = "strict" && "${MODS}" = "unconfined" ]]; then
@@ -299,19 +296,21 @@ selinux-policy-2_pkg_postinst() {
 			einfo "Inserting the following modules into the ${type} module store: ${MODS}"
 
 			cd "${ROOT}/usr/share/selinux/${type}" || die "Could not enter /usr/share/selinux/${type}"
+
+			local module_args=()
 			for mod in ${MODS}; do
 				if [[ -f "${mod}.pp" ]]; then
-					COMMAND="${mod}.pp ${COMMAND}"
+					module_args+=( "${mod}.pp" )
 				elif [[ -f "${mod}.cil" ]]; then
-					COMMAND="${mod}.cil ${COMMAND}"
+					module_args+=( "${mod}.cil" )
 				fi
 			done
 
-			semodule ${root_opts} -s ${type} -i ${COMMAND}
+			semodule "${root_opts[@]}" -s "${type}" -i "${module_args[@]}"
 			if [[ $? -ne 0 ]]; then
 				ewarn "SELinux module load failed. Trying full reload..."
 
-				semodule ${root_opts} -s ${type} -i ./*.pp
+				semodule "${root_opts[@]}" -s "${type}" -i ./*.pp
 
 				if [[ $? -ne 0 ]]; then
 					ewarn "Failed to reload SELinux policies."
@@ -333,7 +332,6 @@ selinux-policy-2_pkg_postinst() {
 			else
 				einfo "SELinux modules loaded successfully."
 			fi
-			COMMAND=""
 		fi
 	done
 
@@ -386,22 +384,22 @@ selinux-policy-2_pkg_postrm() {
 	fi
 
 	# Set root path and don't load policy into the kernel when cross compiling
-	local root_opts=""
-	if [[ -n ${ROOT} ]]; then
-		root_opts="-p ${ROOT} -n"
+	local root_opts=()
+	if [[ -n "${ROOT}" ]]; then
+		root_opts=( "-p" "${ROOT}" "-n" )
 	fi
 
 	# build up the command in the case of multiple modules
-	local COMMAND
+	local module_args=()
 	for mod in ${MODS}; do
-		COMMAND="-r ${mod} ${COMMAND}"
+		module_args+=( "-r" "${mod}" )
 	done
 
 	for type in targeted strict mcs mls; do
 		if use "selinux_policy_types_${type}"; then
 			einfo "Removing the following modules from the ${type} module store: ${MODS}"
 
-			semodule ${root_opts} -s ${type} ${COMMAND}
+			semodule "${root_opts[@]}" -s "${type}" "${module_args[@]}"
 			if [[ $? -ne 0 ]]; then
 				ewarn "SELinux module unload failed."
 			else
-- 
2.54.0