Skip to content

Commit

Permalink
go/internal/gcimporter: fail gracefully on export format skew
Browse files Browse the repository at this point in the history 
Port of changes made to compiler in
https://go-review.googlesource.com/27814.

Correctly handle export format version 0 (we only do this
in x/tools/gcimporter15 at the moment - this is a backport
of that code for struct fields).

Added tests for version handling and detection of corrupted
export data.

Fixes golang#16881.

Change-Id: I246553c689c89ef5c7fedd1e43717504c2838804
Reviewed-on: https://go-review.googlesource.com/27816
Reviewed-by: Matthew Dempsky <[email protected]>
  • Loading branch information
@griesemer
griesemer committed Aug 26, 2016
1 parent bee4206 commit fba8f4d
Show file tree
Hide file tree
Showing 6 changed files with 158 additions and 30 deletions.
94 changes: 66 additions & 28 deletions src/go/internal/gcimporter/bimport.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,7 @@ import (
"go/token"
"go/types"
"sort"
"strconv"
"strings"
"unicode"
"unicode/utf8"
Expand All @@ -21,6 +22,7 @@ type importer struct {
data []byte
path string
buf []byte // for reading strings
version int // export format version

// object lists
strList []string // in order of appearance
Expand All @@ -40,17 +42,28 @@ type importer struct {

// BImportData imports a package from the serialized package data
// and returns the number of bytes consumed and a reference to the package.
// If data is obviously malformed, an error is returned but in
// general it is not recommended to call BImportData on untrusted data.
func BImportData(imports map[string]*types.Package, data []byte, path string) (int, *types.Package, error) {
// If the export data version is not recognized or the format is otherwise
// compromised, an error is returned.
func BImportData(imports map[string]*types.Package, data []byte, path string) (_ int, _ *types.Package, err error) {
// catch panics and return them as errors
defer func() {
if e := recover(); e != nil {
// The package (filename) causing the problem is added to this
// error by a wrapper in the caller (Import in gcimporter.go).
err = fmt.Errorf("cannot import, possibly version skew (%v) - reinstall package", e)
}
}()

p := importer{
imports: imports,
data: data,
path: path,
version: -1, // unknown version
strList: []string{""}, // empty string is mapped to 0
}

// read version info
var versionstr string
if b := p.rawByte(); b == 'c' || b == 'd' {
// Go1.7 encoding; first byte encodes low-level
// encoding format (compact vs debug).
Expand All @@ -63,19 +76,34 @@ func BImportData(imports map[string]*types.Package, data []byte, path string) (i
}
p.trackAllTypes = p.rawByte() == 'a'
p.posInfoFormat = p.int() != 0
const go17version = "v1"
if s := p.string(); s != go17version {
return p.read, nil, fmt.Errorf("importer: unknown export data format: %s (imported package compiled with old compiler?)", s)
versionstr = p.string()
if versionstr == "v1" {
p.version = 0
}
} else {
// Go1.8 extensible encoding
const exportVersion = "version 1"
if s := p.rawStringln(b); s != exportVersion {
return p.read, nil, fmt.Errorf("importer: unknown export data format: %s (imported package compiled with old compiler?)", s)
// read version string and extract version number (ignore anything after the version number)
versionstr = p.rawStringln(b)
if s := strings.SplitN(versionstr, " ", 3); len(s) >= 2 && s[0] == "version" {
if v, err := strconv.Atoi(s[1]); err == nil && v > 0 {
p.version = v
}
}
}

// read version specific flags - extend as necessary
switch p.version {
// case 2:
// ...
// fallthrough
case 1:
p.debugFormat = p.rawStringln(p.rawByte()) == "debug"
p.trackAllTypes = p.int() != 0
p.posInfoFormat = p.int() != 0
case 0:
// Go1.7 encoding format - nothing to do here
default:
errorf("unknown export format version %d (%q)", p.version, versionstr)
}

// --- generic export data ---
Expand All @@ -99,7 +127,7 @@ func BImportData(imports map[string]*types.Package, data []byte, path string) (i

// self-verification
if count := p.int(); count != objcount {
panic(fmt.Sprintf("got %d objects; want %d", objcount, count))
errorf("got %d objects; want %d", objcount, count)
}

// ignore compiler-specific import data
Expand Down Expand Up @@ -127,6 +155,10 @@ func BImportData(imports map[string]*types.Package, data []byte, path string) (i
return p.read, pkg, nil
}

func errorf(format string, args ...interface{}) {
panic(fmt.Sprintf(format, args...))
}

func (p *importer) pkg() *types.Package {
// if the package was seen before, i is its index (>= 0)
i := p.tagOrIndex()
Expand All @@ -136,7 +168,7 @@ func (p *importer) pkg() *types.Package {

// otherwise, i is the package tag (< 0)
if i != packageTag {
panic(fmt.Sprintf("unexpected package tag %d", i))
errorf("unexpected package tag %d", i)
}

// read package data
Expand All @@ -145,13 +177,13 @@ func (p *importer) pkg() *types.Package {

// we should never see an empty package name
if name == "" {
panic("empty package name in import")
errorf("empty package name in import")
}

// an empty path denotes the package we are currently importing;
// it must be the first package we see
if (path == "") != (len(p.pkgList) == 0) {
panic(fmt.Sprintf("package path %q for pkg index %d", path, len(p.pkgList)))
errorf("package path %q for pkg index %d", path, len(p.pkgList))
}

// if the package was imported before, use that one; otherwise create a new one
Expand All @@ -163,7 +195,7 @@ func (p *importer) pkg() *types.Package {
pkg = types.NewPackage(path, name)
p.imports[path] = pkg
} else if pkg.Name() != name {
panic(fmt.Sprintf("conflicting names %s and %s for package %q", pkg.Name(), name, path))
errorf("conflicting names %s and %s for package %q", pkg.Name(), name, path)
}
p.pkgList = append(p.pkgList, pkg)

Expand All @@ -180,7 +212,7 @@ func (p *importer) declare(obj types.Object) {
// imported.
// (See also the comment in cmd/compile/internal/gc/bimport.go importer.obj,
// switch case importing functions).
panic(fmt.Sprintf("inconsistent import:\n\t%v\npreviously imported as:\n\t%v\n", alt, obj))
errorf("inconsistent import:\n\t%v\npreviously imported as:\n\t%v\n", alt, obj)
}
}

Expand Down Expand Up @@ -211,7 +243,7 @@ func (p *importer) obj(tag int) {
p.declare(types.NewFunc(token.NoPos, pkg, name, sig))

default:
panic(fmt.Sprintf("unexpected object tag %d", tag))
errorf("unexpected object tag %d", tag)
}
}

Expand Down Expand Up @@ -283,7 +315,7 @@ func (p *importer) typ(parent *types.Package) types.Type {
}

if _, ok := obj.(*types.TypeName); !ok {
panic(fmt.Sprintf("pkg = %s, name = %s => %s", parent, name, obj))
errorf("pkg = %s, name = %s => %s", parent, name, obj)
}

// associate new named type with obj if it doesn't exist yet
Expand Down Expand Up @@ -390,7 +422,7 @@ func (p *importer) typ(parent *types.Package) types.Type {

// no embedded interfaces with gc compiler
if p.int() != 0 {
panic("unexpected embedded interface")
errorf("unexpected embedded interface")
}

t := types.NewInterface(p.methodList(parent), nil)
Expand Down Expand Up @@ -426,14 +458,15 @@ func (p *importer) typ(parent *types.Package) types.Type {
case 3 /* Cboth */ :
dir = types.SendRecv
default:
panic(fmt.Sprintf("unexpected channel dir %d", d))
errorf("unexpected channel dir %d", d)
}
val := p.typ(parent)
*t = *types.NewChan(dir, val)
return t

default:
panic(fmt.Sprintf("unexpected type tag %d", i))
errorf("unexpected type tag %d", i)
panic("unreachable")
}
}

Expand Down Expand Up @@ -464,7 +497,7 @@ func (p *importer) field(parent *types.Package) *types.Var {
case *types.Named:
name = typ.Obj().Name()
default:
panic("anonymous field expected")
errorf("anonymous field expected")
}
anonymous = true
}
Expand Down Expand Up @@ -498,6 +531,10 @@ func (p *importer) fieldName(parent *types.Package) (*types.Package, string) {
// use the imported package instead
pkg = p.pkgList[0]
}
if p.version == 0 && name == "_" {
// version 0 didn't export a package for _ fields
return pkg, name
}
if name != "" && !exported(name) {
if name == "?" {
name = ""
Expand Down Expand Up @@ -539,7 +576,7 @@ func (p *importer) param(named bool) (*types.Var, bool) {
if named {
name = p.string()
if name == "" {
panic("expected named parameter")
errorf("expected named parameter")
}
if name != "_" {
pkg = p.pkg()
Expand Down Expand Up @@ -577,7 +614,8 @@ func (p *importer) value() constant.Value {
case stringTag:
return constant.MakeString(p.string())
default:
panic(fmt.Sprintf("unexpected value tag %d", tag))
errorf("unexpected value tag %d", tag)
panic("unreachable")
}
}

Expand Down Expand Up @@ -640,7 +678,7 @@ func (p *importer) tagOrIndex() int {
func (p *importer) int() int {
x := p.int64()
if int64(int(x)) != x {
panic("exported integer too large")
errorf("exported integer too large")
}
return int(x)
}
Expand Down Expand Up @@ -679,20 +717,20 @@ func (p *importer) string() string {

func (p *importer) marker(want byte) {
if got := p.rawByte(); got != want {
panic(fmt.Sprintf("incorrect marker: got %c; want %c (pos = %d)", got, want, p.read))
errorf("incorrect marker: got %c; want %c (pos = %d)", got, want, p.read)
}

pos := p.read
if n := int(p.rawInt64()); n != pos {
panic(fmt.Sprintf("incorrect position: got %d; want %d", n, pos))
errorf("incorrect position: got %d; want %d", n, pos)
}
}

// rawInt64 should only be used by low-level decoders.
func (p *importer) rawInt64() int64 {
i, err := binary.ReadVarint(p)
if err != nil {
panic(fmt.Sprintf("read error: %v", err))
errorf("read error: %v", err)
}
return i
}
Expand Down Expand Up @@ -727,7 +765,7 @@ func (p *importer) rawByte() byte {
case '|':
// nothing to do
default:
panic("unexpected escape sequence in export data")
errorf("unexpected escape sequence in export data")
}
}
p.data = p.data[r:]
Expand Down
4 changes: 2 additions & 2 deletions src/go/internal/gcimporter/gcimporter.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -106,7 +106,7 @@ func Import(packages map[string]*types.Package, path, srcDir string) (pkg *types
f.Close()
if err != nil {
// add file name to error
err = fmt.Errorf("reading export data: %s: %v", filename, err)
err = fmt.Errorf("%s: %v", filename, err)
}
}()

Expand All @@ -118,7 +118,7 @@ func Import(packages map[string]*types.Package, path, srcDir string) (pkg *types

switch hdr {
case "$$\n":
err = fmt.Errorf("cannot import %s: old export format no longer supported (recompile library)", path)
err = fmt.Errorf("import %q: old export format no longer supported (recompile library)", path)
case "$$B\n":
var data []byte
data, err = ioutil.ReadAll(buf)
Expand Down
65 changes: 65 additions & 0 deletions src/go/internal/gcimporter/gcimporter_test.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,7 @@
package gcimporter

import (
"bytes"
"fmt"
"internal/testenv"
"io/ioutil"
Expand Down Expand Up @@ -118,6 +119,70 @@ func TestImportTestdata(t *testing.T) {
}
}

func TestVersionHandling(t *testing.T) {
skipSpecialPlatforms(t) // we really only need to exclude nacl platforms, but this is fine

// This package only handles gc export data.
if runtime.Compiler != "gc" {
t.Skipf("gc-built packages not available (compiler = %s)", runtime.Compiler)
return
}

const dir = "./testdata/versions"
list, err := ioutil.ReadDir(dir)
if err != nil {
t.Fatal(err)
}

for _, f := range list {
name := f.Name()
if !strings.HasSuffix(name, ".a") {
continue // not a package file
}
if strings.Contains(name, "corrupted") {
continue // don't process a leftover corrupted file
}
pkgpath := "./" + name[:len(name)-2]

// test that export data can be imported
_, err := Import(make(map[string]*types.Package), pkgpath, dir)
if err != nil {
t.Errorf("import %q failed: %v", pkgpath, err)
continue
}

// create file with corrupted export data
// 1) read file
data, err := ioutil.ReadFile(filepath.Join(dir, name))
if err != nil {
t.Fatal(err)
}
// 2) find export data
i := bytes.Index(data, []byte("\n$$B\n")) + 5
j := bytes.Index(data[i:], []byte("\n$$\n")) + i
if i < 0 || j < 0 || i > j {
t.Fatalf("export data section not found (i = %d, j = %d)", i, j)
}
// 3) corrupt the data (increment every 7th byte)
for k := j - 13; k >= i; k -= 7 {
data[k]++
}
// 4) write the file
pkgpath += "_corrupted"
filename := filepath.Join(dir, pkgpath) + ".a"
ioutil.WriteFile(filename, data, 0666)
defer os.Remove(filename)

// test that importing the corrupted file results in an error
_, err = Import(make(map[string]*types.Package), pkgpath, dir)
if err == nil {
t.Errorf("import corrupted %q succeeded", pkgpath)
} else if msg := err.Error(); !strings.Contains(msg, "version skew") {
t.Errorf("import %q error incorrect (%s)", pkgpath, msg)
}
}
}

func TestImportStdLib(t *testing.T) {
skipSpecialPlatforms(t)

Expand Down
Loading

0 comments on commit fba8f4d

Please sign in to comment.