Strip all filename and position info when -tiny is passed (#128)

Co-authored-by: pagran <pagran@protonmail.com>
Co-authored-by: lu4p <lu4p@pm.me>

import_obfuscation.go

@@ -17,8 +17,9 @@ import (
 // pkgInfo stores a parsed go archive/object file,
 // and the original path to which it was read from.
 type pkgInfo struct {
-	pkg  *goobj2.Package
-	path string
+	pkg     *goobj2.Package
+	path    string
+	private bool
 }
 
 // dataType signifies whether the Data portion of a
@@ -52,24 +53,26 @@ func obfuscateImports(objPath, importCfgPath string) (map[string]string, error)
 	if err != nil {
 		return nil, fmt.Errorf("error parsing main objfile: %v", err)
 	}
-	privatePkgs := []pkgInfo{{mainPkg, objPath}}
+	pkgs := []pkgInfo{{mainPkg, objPath, true}}
 
 	// build list of imported packages that are private
 	for pkgPath, info := range importCfg {
-		if isPrivate(pkgPath) {
+		// if the '-tiny' flag is passed, we will strip filename
+		// and position info of every package, but not garble anything
+		if private := isPrivate(pkgPath); envGarbleTiny || private {
 			pkg, err := goobj2.Parse(info.Path, pkgPath, importCfg)
 			if err != nil {
 				return nil, fmt.Errorf("error parsing objfile %s at %s: %v", pkgPath, info.Path, err)
 			}
 
-			privatePkgs = append(privatePkgs, pkgInfo{pkg, info.Path})
+			pkgs = append(pkgs, pkgInfo{pkg, info.Path, private})
 		}
 	}
 
 	var sb strings.Builder
 	var buf bytes.Buffer
 	garbledImports := make(map[string]string)
-	for _, p := range privatePkgs {
+	for _, p := range pkgs {
 		// log.Printf("++ Obfuscating object file for %s ++", p.pkg.ImportPath)
 		for _, am := range p.pkg.ArchiveMembers {
 			// log.Printf("\t## Obfuscating archive member %s ##", am.ArchiveHeader.Name)
@@ -80,6 +83,13 @@ func obfuscateImports(objPath, importCfgPath string) (map[string]string, error)
 				continue
 			}
 
+			// not part of a private package, so just strip filename
+			// and position info and move on
+			if !p.private {
+				stripPCLinesAndNames(&am)
+				continue
+			}
+
 			// add all private import paths to a list to garble
 			var privImports privateImports
 			privImports.privatePaths, privImports.privateNames = explodeImportPath(p.pkg.ImportPath)
@@ -149,6 +159,37 @@ func obfuscateImports(objPath, importCfgPath string) (map[string]string, error)
 	return garbledImports, nil
 }
 
+// stripPCLinesAndNames removes all filename and position info
+// from an archive member.
+func stripPCLinesAndNames(am *goobj2.ArchiveMember) {
+	lists := [][]*goobj2.Sym{am.SymDefs, am.NonPkgSymDefs, am.NonPkgSymRefs}
+	for _, list := range lists {
+		for _, s := range list {
+			if s.Func == nil {
+				continue
+			}
+
+			for _, inl := range s.Func.InlTree {
+				inl.Line = 1
+			}
+
+			s.Func.PCFile = nil
+			s.Func.PCLine = nil
+			s.Func.PCInline = nil
+
+			// remove unneeded debug aux symbols
+			s.Func.DwarfInfo = nil
+			s.Func.DwarfLoc = nil
+			s.Func.DwarfRanges = nil
+			s.Func.DwarfDebugLines = nil
+
+		}
+	}
+
+	// remove dwarf file list, it isn't needed as we pass "-w, -s" to the linker
+	am.DWARFFileList = nil
+}
+
 // explodeImportPath returns lists of import paths
 // and package names that could all potentially be
 // in symbol names of the package that imported 'path'.
@@ -246,6 +287,7 @@ func garbleSymbols(am *goobj2.ArchiveMember, privImports privateImports, garbled
 		for _, s := range list {
 			// skip debug symbols, and remove the debug symbol's data to save space
 			if s.Kind >= goobj2.SDWARFINFO && s.Kind <= goobj2.SDWARFLINES {
+				s.Size = 0
 				s.Data = nil
 				continue
 			}
@@ -291,6 +333,15 @@ func garbleSymbols(am *goobj2.ArchiveMember, privImports privateImports, garbled
 				}
 				for _, inl := range s.Func.InlTree {
 					inl.Func.Name = garbleSymbolName(inl.Func.Name, privImports, garbledImports, sb)
+					if envGarbleTiny {
+						inl.Line = 1
+					}
+				}
+
+				if envGarbleTiny {
+					s.Func.PCFile = nil
+					s.Func.PCLine = nil
+					s.Func.PCInline = nil
 				}
 
 				// remove unneeded debug aux symbols

line_obfuscator.go

@@ -99,11 +99,6 @@ func transformLineInfo(file *ast.File) ([]string, *ast.File) {
 			return true
 		}
 
-		if envGarbleTiny {
-			funcDecl.Doc = prependComment(funcDecl.Doc, &ast.Comment{Text: "//line :1"})
-			return true
-		}
-
 		comment := &ast.Comment{Text: fmt.Sprintf("//line %c.go:%d", nameCharset[mathrand.Intn(len(nameCharset))], 1+newLines[funcCounter])}
 		funcDecl.Doc = prependComment(funcDecl.Doc, comment)
 		funcCounter++

main.go

@@ -548,7 +548,9 @@ func transformCompile(args []string) ([]string, error) {
 			// messy.
 			name = "_cgo_" + name
 		default:
-			extraComments, file = transformLineInfo(file)
+			if !envGarbleTiny {
+				extraComments, file = transformLineInfo(file)
+			}
 			file = transformGo(file, info, blacklist)
 
 			// Uncomment for some quick debugging. Do not delete.

testdata/scripts/asm.txt

@@ -7,6 +7,11 @@ binsubstr main$exe 'privateAdd' 'PublicAdd'
 
 [short] stop # no need to verify this with -short
 
+garble -tiny build
+exec ./main
+cmp stderr main.stderr
+binsubstr main$exe 'privateAdd' 'PublicAdd'
+
 go build
 exec ./main
 cmp stderr main.stderr

testdata/scripts/cgo.txt

@@ -7,6 +7,11 @@ binsubstr main$exe 'privateAdd'
 
 [short] stop # no need to verify this with -short
 
+garble -tiny build
+exec ./main
+cmp stderr main.stderr
+binsubstr main$exe 'privateAdd'
+
 go build
 exec ./main
 cmp stderr main.stderr

testdata/scripts/tiny.txt

@@ -1,43 +1,32 @@
 env GOPRIVATE=test/main
 
-env TINY_PATTERN='^\/\/line :1$'
-env DEFAULT_PATTERN='^\/\/line \w\.go:[1-9][0-9]*$'
-env DEFAULT_STACK_PATTERN='^\t\w\.go:[1-9][0-9]*(\s\+0x[0-9a-f]+)?'
-env TINY_STACK_PATTERN='^\t\?\?:[0-9][0-9]*(\s\+0x[0-9a-f]+)?$'
-
 # Tiny mode
-garble -tiny -debugdir=.obf-src build
-
-grep $TINY_PATTERN .obf-src/main/main.go
-! grep $DEFAULT_PATTERN .obf-src/main/main.go
-
-! exec ./main$exe
-! stderr 'main\.go'
-! stderr $DEFAULT_STACK_PATTERN
-stderr $TINY_STACK_PATTERN
+garble -tiny build
+exec ./main$exe
+stderr '\? 0'
 
 [short] stop # no need to verify this with -short
 
 # Default mode
-
 garble -debugdir=.obf-src build
 
 # Check for file name leak protection
-grep $TINY_PATTERN .obf-src/main/main.go
+grep '^\/\/line :1$' .obf-src/main/main.go
 
 # Check for default line obfuscation
-grep $DEFAULT_PATTERN .obf-src/main/main.go
+grep '^\/\/line \w\.go:[1-9][0-9]*$' .obf-src/main/main.go
+exec ./main$exe
 
-! exec ./main$exe
-! stderr 'main\.go'
-! stderr $TINY_STACK_PATTERN
-stderr $DEFAULT_STACK_PATTERN
+stderr '\w\.go [1-9]'
 
 -- go.mod --
 module test/main
 -- main.go --
 package main
 
+import "runtime"
+
 func main() {
-	panic("Test")
-}
+	_, file, line, _ := runtime.Caller(0)
+	println(file, line)
+}