home: add permcheck option

internal/home/home.go

@@ -686,18 +686,26 @@ func run(opts options, clientBuildFS fs.FS, done chan struct{}) {
 		}
 	}
 
-	if permcheck.NeedsMigration(confPath) {
-		permcheck.Migrate(Context.workDir, dataDir, statsDir, querylogDir, confPath)
+	if opts.checkPermissions {
+		permCheck(confPath, dataDir, statsDir, querylogDir)
 	}
 
-	permcheck.Check(Context.workDir, dataDir, statsDir, querylogDir, confPath)
-
 	Context.web.start()
 
 	// Wait for other goroutines to complete their job.
 	<-done
 }
 
+// permCheck checks and migrates permissions of the files and directories used
+// by AdGuard Home, if needed.
+func permCheck(confPath, dataDir, statsDir, querylogDir string) {
+	if permcheck.NeedsMigration(confPath) {
+		permcheck.Migrate(Context.workDir, dataDir, statsDir, querylogDir, confPath)
+	}
+
+	permcheck.Check(Context.workDir, dataDir, statsDir, querylogDir, confPath)
+}
+
 // initUsers initializes context auth module.  Clears config users field.
 func initUsers() (auth *Auth, err error) {
 	sessFilename := filepath.Join(Context.getDataDir(), "sessions.db")

internal/home/options.go

@@ -78,6 +78,10 @@ type options struct {
 	// localFrontend forces AdGuard Home to use the frontend files from disk
 	// rather than the ones that have been compiled into the binary.
 	localFrontend bool
+
+	// checkPermissions enables the migration of permissions for the
+	// security-sensitive files, including the working directory itself.
+	checkPermissions bool
 }
 
 // initCmdLineOpts completes initialization of the global command-line option
@@ -305,6 +309,14 @@ var cmdLineOpts = []cmdLineOpt{{
 	description:     "Run in GL-Inet compatibility mode.",
 	longName:        "glinet",
 	shortName:       "",
+}, {
+	updateWithValue: nil,
+	updateNoValue:   func(o options) (options, error) { o.checkPermissions = true; return o, nil },
+	effect:          nil,
+	serialize:       func(o options) (val string, ok bool) { return "", o.checkPermissions },
+	description:     "Check and migrate permissions of security-sensitive files.",
+	longName:        "permcheck",
+	shortName:       "",
 }, {
 	updateWithValue: nil,
 	updateNoValue:   nil,