TUN-3826: Use go-fips when building cloudflared for linux/amd64

Makefile

@@ -1,10 +1,17 @@
 VERSION       := $(shell git describe --tags --always --dirty="-dev" --match "[0-9][0-9][0-9][0-9].*.*")
-DATE          := $(shell date -u '+%Y-%m-%d-%H%M UTC')
-VERSION_FLAGS := -ldflags='-X "main.Version=$(VERSION)" -X "main.BuildTime=$(DATE)"'
 MSI_VERSION   := $(shell git tag -l --sort=v:refname | grep "w" | tail -1 | cut -c2-)
 #MSI_VERSION expects the format of the tag to be: (wX.X.X). Starts with the w character to not break cfsetup.
 #e.g. w3.0.1 or w4.2.10. It trims off the w character when creating the MSI.
 
+ifeq ($(FIPS), true)
+	GO_BUILD_TAGS := "$(GO_BUILD_TAGS) fips"
+	VERSION := $(VERSION)-fips
+	MSI_VERSION := $(MSI_VERSION)-fips
+endif
+
+DATE          := $(shell date -u '+%Y-%m-%d-%H%M UTC')
+VERSION_FLAGS := -ldflags='-X "main.Version=$(VERSION)" -X "main.BuildTime=$(DATE)"'
+
 IMPORT_PATH   := github.com/cloudflare/cloudflared
 PACKAGE_DIR   := $(CURDIR)/packaging
 INSTALL_BINDIR := /usr/bin/
@@ -71,7 +78,7 @@ clean:
 
 .PHONY: cloudflared
 cloudflared: tunnel-deps
-	GOOS=$(TARGET_OS) GOARCH=$(TARGET_ARCH) go build -v -mod=vendor $(VERSION_FLAGS) $(IMPORT_PATH)/cmd/cloudflared
+	GOOS=$(TARGET_OS) GOARCH=$(TARGET_ARCH) go build -v -mod=vendor -tags $(GO_BUILD_TAGS) $(VERSION_FLAGS) $(IMPORT_PATH)/cmd/cloudflared
 
 .PHONY: container
 container:

cfsetup.yaml

@@ -1,26 +1,30 @@
 pinned_go: &pinned_go go=1.15.7-1
+pinned_go_fips: &pinned_go_fips go-fips=1.15.5-3
+
 build_dir: &build_dir /cfsetup_build
 default-flavor: buster
 stretch: &stretch
   build:
     build_dir: *build_dir
     builddeps:
-      - *pinned_go
+      - *pinned_go_fips
       - build-essential
     post-cache:
       - export GOOS=linux
       - export GOARCH=amd64
+      - export GO_BUILD_TAGS=fips
       - make cloudflared
   build-deb:
     build_dir: *build_dir
     builddeps:
-      - *pinned_go
+      - *pinned_go_fips
       - build-essential
       - fakeroot
       - rubygem-fpm
     post-cache:
       - export GOOS=linux
       - export GOARCH=amd64
+      - export GO_BUILD_TAGS=fips
       - make cloudflared-deb
   build-deb-arm64:
     build_dir: *build_dir
@@ -36,7 +40,7 @@ stretch: &stretch
   publish-deb:
     build_dir: *build_dir
     builddeps:
-      - *pinned_go
+      - *pinned_go_fips
       - build-essential
       - fakeroot
       - rubygem-fpm
@@ -44,20 +48,22 @@ stretch: &stretch
     post-cache:
       - export GOOS=linux
       - export GOARCH=amd64
+      - export GO_BUILD_TAGS=fips
       - make publish-deb
   release-linux-amd64:
     build_dir: *build_dir
     builddeps:
-      - *pinned_go
+      - *pinned_go_fips
       - build-essential
     post-cache:
       - export GOOS=linux
       - export GOARCH=amd64
+      - export GO_BUILD_TAGS=fips
       - make release
   github-release-linux-amd64:
     build_dir: *build_dir
     builddeps:
-      - *pinned_go
+      - *pinned_go_fips
       - build-essential
       - python3-setuptools
       - python3-pip
@@ -66,6 +72,7 @@ stretch: &stretch
     post-cache:
       - export GOOS=linux
       - export GOARCH=amd64
+      - export GO_BUILD_TAGS=fips
       - make github-release
   release-linux-armv6:
     build_dir: *build_dir
@@ -185,11 +192,12 @@ stretch: &stretch
   test:
     build_dir: *build_dir
     builddeps:
-      - *pinned_go
+      - *pinned_go_fips
       - build-essential
     post-cache:
       - export GOOS=linux
       - export GOARCH=amd64
+      - export GO_BUILD_TAGS=fips
       # cd to a non-module directory: https://github.com/golang/go/issues/24250
       - (cd / && go get github.com/BurntSushi/go-sumtype)
       - export PATH="$HOME/go/bin:$PATH"

cmd/cloudflared/fips.go

@@ -0,0 +1,5 @@
+// +build fips
+
+package main
+
+import _ "crypto/tls/fipsonly"