Update filename and add line number obfuscation (#94)
Fixes #2. Line numbers are now obfuscated, via `//line` comments. Filenames are now obfuscated via `//line` comments, instead of changing the actual filename. New flag `-tiny` to reduce the binary size, at the cost of reversibility.pull/99/head
pagran
4 years ago
committed by
GitHub
parent
7df14ad860
commit
2735555ab2
@ -0,0 +1,109 @@
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package main
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import (
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"fmt"
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"go/ast"
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mathrand "math/rand"
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"strings"
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"golang.org/x/tools/go/ast/astutil"
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)
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const (
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// PosMax is the largest line or column value that can be represented without loss.
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// Source: https://go.googlesource.com/go/+/refs/heads/master/src/cmd/compile/internal/syntax/pos.go#11
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PosMax = 1 << 30
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// PosMin is the smallest correct value for the line number.
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// Source: https://go.googlesource.com/go/+/refs/heads/master/src/cmd/compile/internal/syntax/parser_test.go#229
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PosMin = 1
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)
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func prependComment(group *ast.CommentGroup, comment *ast.Comment) *ast.CommentGroup {
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if group == nil {
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return &ast.CommentGroup{List: []*ast.Comment{comment}}
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}
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group.List = append([]*ast.Comment{comment}, group.List...)
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return group
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}
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// Remove all comments from CommentGroup except //go: directives.
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func clearCommentGroup(group *ast.CommentGroup) *ast.CommentGroup {
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if group == nil {
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return nil
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}
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var comments []*ast.Comment
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for _, comment := range group.List {
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if strings.HasPrefix(comment.Text, "//go:") {
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comments = append(comments, &ast.Comment{Text: comment.Text})
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}
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}
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if len(comments) == 0 {
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return nil
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}
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return &ast.CommentGroup{List: comments}
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}
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// Remove all comments from Doc (if any) except //go: directives.
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func clearNodeComments(node ast.Node) {
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switch n := node.(type) {
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case *ast.Field:
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n.Doc = clearCommentGroup(n.Doc)
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case *ast.ImportSpec:
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n.Doc = clearCommentGroup(n.Doc)
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case *ast.ValueSpec:
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n.Doc = clearCommentGroup(n.Doc)
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case *ast.TypeSpec:
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n.Doc = clearCommentGroup(n.Doc)
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case *ast.GenDecl:
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n.Doc = clearCommentGroup(n.Doc)
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case *ast.FuncDecl:
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n.Doc = clearCommentGroup(n.Doc)
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case *ast.File:
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n.Doc = clearCommentGroup(n.Doc)
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}
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}
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func findBuildTags(commentGroups []*ast.CommentGroup) (buildTags []string) {
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for _, group := range commentGroups {
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for _, comment := range group.List {
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if !strings.Contains(comment.Text, "+build") {
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continue
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}
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buildTags = append(buildTags, comment.Text)
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}
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}
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return buildTags
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}
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func transformLineInfo(fileIndex int, file *ast.File) ([]string, *ast.File) {
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// Save build tags and add file name leak protection
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extraComments := append(findBuildTags(file.Comments), "", "//line :1")
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file.Comments = nil
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pre := func(cursor *astutil.Cursor) bool {
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node := cursor.Node()
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clearNodeComments(node)
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funcDecl, ok := node.(*ast.FuncDecl)
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if !ok {
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return true
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}
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if envGarbleTiny {
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funcDecl.Doc = prependComment(funcDecl.Doc, &ast.Comment{Text: "//line :1"})
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return true
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}
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// TODO: Optimize the generated values of line numbers to reduce space usage.
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linePos := hashWithAsUint64(buildInfo.buildID, fmt.Sprintf("%d:%s", fileIndex, funcDecl.Name), PosMin, PosMax)
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comment := &ast.Comment{Text: fmt.Sprintf("//line %c.go:%d", nameCharset[mathrand.Intn(len(nameCharset))], linePos)}
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funcDecl.Doc = prependComment(funcDecl.Doc, comment)
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return true
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}
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return extraComments, astutil.Apply(file, pre, nil).(*ast.File)
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}
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@ -0,0 +1,41 @@
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env TINY_PATTERN='^\/\/line :1$'
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env DEFAULT_PATTERN='^\/\/line \w\.go:[1-9][0-9]*$'
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env DEFAULT_STACK_PATTERN='^\t\w\.go:[1-9][0-9]*(\s\+0x[0-9a-f]+)?'
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env TINY_STACK_PATTERN='^\t\?\?:[0-9][0-9]*(\s\+0x[0-9a-f]+)?$'
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# Tiny mode
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garble -tiny -debugdir=.obf-src build
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grep $TINY_PATTERN .obf-src/main/main.go
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! grep $DEFAULT_PATTERN .obf-src/main/main.go
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! exec ./main$exe
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! stderr 'main\.go'
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! stderr $DEFAULT_STACK_PATTERN
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stderr $TINY_STACK_PATTERN
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[short] stop # no need to verify this with -short
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# Default mode
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garble -debugdir=.obf-src build
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# Check for file name leak protection
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grep $TINY_PATTERN .obf-src/main/main.go
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# Check for default line obfuscation
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grep $DEFAULT_PATTERN .obf-src/main/main.go
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! exec ./main$exe
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! stderr 'main\.go'
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! stderr $TINY_STACK_PATTERN
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stderr $DEFAULT_STACK_PATTERN
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-- go.mod --
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module main
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-- main.go --
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package main
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func main() {
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panic("Test")
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}
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