[PATCH v2] wireguard-tools: allow generating private_key

[Leonardo Mörlein]

When the uci configuration is created automatically during a very early
stage, where no entropy daemon is set up, generating the key directly is
not an option. Therefore we allow to set the private_key to "generate"
and generate the private key directly before the interface is taken up.

Signed-off-by: Leonardo Mörlein <me at irrelefant.net>
---

v2: Changes since v1:
- The (recently introduced) uci flag "-t" is used to avoid interference
  with potentially existing uncommited user changes. This addresses
  Jo-Philipp Wich's concerns about v1 of the patch.
- The functionality has been moved to a function, so it can be included
  from other files.

References:
- v1 of the patch: https://patchwork.ozlabs.org/project/openwrt/patch/20210108012435.175345-1-me@irrelefant.net/
- uci "-t": https://git.openwrt.org/?p=project/uci.git;a=commit;h=4b3db1179747b6a6779029407984bacef851325c

 .../network/utils/wireguard-tools/Makefile    |  2 +-
 .../utils/wireguard-tools/files/wireguard.sh  | 19 +++++++++++++++++++
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/package/network/utils/wireguard-tools/Makefile b/package/network/utils/wireguard-tools/Makefile
index 5f8da147c1..bcf360329c 100644
--- a/package/network/utils/wireguard-tools/Makefile
+++ b/package/network/utils/wireguard-tools/Makefile
@@ -12,7 +12,7 @@ include $(INCLUDE_DIR)/kernel.mk
 PKG_NAME:=wireguard-tools
 
 PKG_VERSION:=1.0.20210223
-PKG_RELEASE:=2
+PKG_RELEASE:=3
 
 PKG_SOURCE:=wireguard-tools-$(PKG_VERSION).tar.xz
 PKG_SOURCE_URL:=https://git.zx2c4.com/wireguard-tools/snapshot/
diff --git a/package/network/utils/wireguard-tools/files/wireguard.sh b/package/network/utils/wireguard-tools/files/wireguard.sh
index 63261aea71..845f9eb902 100644
--- a/package/network/utils/wireguard-tools/files/wireguard.sh
+++ b/package/network/utils/wireguard-tools/files/wireguard.sh
@@ -95,6 +95,23 @@ proto_wireguard_setup_peer() {
 	fi
 }
 
+ensure_key_is_generated() {
+	local private_key
+	private_key="$(uci get network."$1".private_key)"
+
+	if [ "$private_key" == "generate" ]; then
+		local ucitmp
+		oldmask="$(umask)"
+		umask 077
+		ucitmp="$(mktemp -d)"
+		private_key="$("${WG}" genkey)"
+		uci -q -t "$ucitmp" set network."$1".private_key="$private_key" && \
+			uci -q -t "$ucitmp" commit network
+		rm -rf "$ucitmp"
+		umask "$oldmask"
+	fi
+}
+
 proto_wireguard_setup() {
 	local config="$1"
 	local wg_dir="/tmp/wireguard"
@@ -104,6 +121,8 @@ proto_wireguard_setup() {
 	local listen_port
 	local mtu
 
+	ensure_key_is_generated "${config}"
+
 	config_load network
 	config_get private_key "${config}" "private_key"
 	config_get listen_port "${config}" "listen_port"
-- 
2.33.0