xattr: optimize storage, store as binary instead of bae64
Values a binary-safe, there is no need to base64-encode them. Old, base64-encoded values are supported transparently on reading. Writing xattr values now always writes them binary.
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@ -36,17 +36,16 @@ func (fs *FS) GetXAttr(path string, attr string, context *fuse.Context) ([]byte,
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if err != nil {
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return nil, fuse.ToStatus(err)
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}
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cData64, err := xattr.Get(cPath, cAttr)
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encryptedData, err := xattr.Get(cPath, cAttr)
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if err != nil {
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return nil, unpackXattrErr(err)
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}
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// xattr data is decrypted like a symlink target
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data, err := fs.decryptSymlinkTarget(string(cData64))
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data, err := fs.decryptXattrValue(encryptedData)
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if err != nil {
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tlog.Warn.Printf("GetXAttr: %v", err)
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return nil, fuse.EIO
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}
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return []byte(data), fuse.OK
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return data, fuse.OK
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}
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// SetXAttr implements pathfs.Filesystem.
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@ -65,9 +64,8 @@ func (fs *FS) SetXAttr(path string, attr string, data []byte, flags int, context
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return fuse.ToStatus(err)
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}
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cAttr := fs.encryptXattrName(attr)
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// xattr data is encrypted like a symlink target
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cData64 := []byte(fs.encryptSymlinkTarget(string(data)))
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return unpackXattrErr(xattr.SetWithFlags(cPath, cAttr, cData64, flags))
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cData := fs.encryptXattrValue(data)
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return unpackXattrErr(xattr.SetWithFlags(cPath, cAttr, cData, flags))
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}
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// RemoveXAttr implements pathfs.Filesystem.
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@ -136,6 +134,37 @@ func (fs *FS) decryptXattrName(cAttr string) (attr string, err error) {
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return attr, nil
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}
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// encryptXattrValue encrypts the xattr value "data".
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// The data is encrypted like a file content block, but without binding it to
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// a file location (block number and file id are set to zero).
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// Special case: an empty value is encrypted to an empty value.
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func (fs *FS) encryptXattrValue(data []byte) (cData []byte) {
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if len(data) == 0 {
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return []byte{}
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}
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return fs.contentEnc.EncryptBlock(data, 0, nil)
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}
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// decryptXattrValue decrypts the xattr value "cData".
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func (fs *FS) decryptXattrValue(cData []byte) (data []byte, err error) {
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if len(cData) == 0 {
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return []byte{}, nil
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}
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data, err1 := fs.contentEnc.DecryptBlock([]byte(cData), 0, nil)
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if err1 == nil {
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return data, nil
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}
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// This backward compatibility is needed to support old
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// file systems having xattr values base64-encoded.
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cData, err2 := fs.nameTransform.B64.DecodeString(string(cData))
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if err2 != nil {
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// Looks like the value was not base64-encoded, but just corrupt.
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// Return the original decryption error: err1
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return nil, err1
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}
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return fs.contentEnc.DecryptBlock([]byte(cData), 0, nil)
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}
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// unpackXattrErr unpacks an error value that we got from xattr.Get/Set/etc
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// and converts it to a fuse status.
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func unpackXattrErr(err error) fuse.Status {
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@ -2,6 +2,7 @@ package defaults
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import (
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"bytes"
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"encoding/base64"
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"fmt"
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"io/ioutil"
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"os"
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@ -11,6 +12,7 @@ import (
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"github.com/pkg/xattr"
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"github.com/rfjakob/gocryptfs/internal/cryptocore"
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"github.com/rfjakob/gocryptfs/tests/test_helpers"
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)
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@ -27,6 +29,14 @@ func TestMain(m *testing.M) {
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os.Exit(1)
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}
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test_helpers.ResetTmpDir(true)
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// Write deterministic diriv so encrypted filenames are deterministic.
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os.Remove(test_helpers.DefaultCipherDir + "/gocryptfs.diriv")
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diriv := []byte("1234567890123456")
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err := ioutil.WriteFile(test_helpers.DefaultCipherDir+"/gocryptfs.diriv", diriv, 0400)
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if err != nil {
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fmt.Println(err)
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os.Exit(1)
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}
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test_helpers.MountOrExit(test_helpers.DefaultCipherDir, test_helpers.DefaultPlainDir, "-zerokey")
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r := m.Run()
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test_helpers.UnmountPanic(test_helpers.DefaultPlainDir)
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@ -161,3 +171,65 @@ func xattrSupported(path string) bool {
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}
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return true
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}
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func TestBase64XattrRead(t *testing.T) {
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attrName := "user.test"
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attrName2 := "user.test2"
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encryptedAttrName := "user.gocryptfs.LB1kHHVrX1OEBdLmj3LTKw"
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encryptedAttrName2 := "user.gocryptfs.d2yn5l7-0zUVqviADw-Oyw"
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attrValue := fmt.Sprintf("test.%d", cryptocore.RandUint64())
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fileName := "TestBase64Xattr"
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encryptedFileName := "BaGak7jIoqAZQMlP0N5uCw"
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plainFn := test_helpers.DefaultPlainDir + "/" + fileName
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encryptedFn := test_helpers.DefaultCipherDir + "/" + encryptedFileName
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err := ioutil.WriteFile(plainFn, nil, 0700)
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if err != nil {
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t.Fatalf("creating empty file failed: %v", err)
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}
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if _, err2 := os.Stat(encryptedFn); os.IsNotExist(err2) {
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t.Fatalf("encrypted file does not exist: %v", err2)
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}
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xattr.Set(plainFn, attrName, []byte(attrValue))
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encryptedAttrValue, err1 := xattr.Get(encryptedFn, encryptedAttrName)
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if err1 != nil {
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t.Fatal(err1)
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}
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xattr.Set(encryptedFn, encryptedAttrName2, encryptedAttrValue)
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plainValue, err := xattr.Get(plainFn, attrName2)
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if err != nil || string(plainValue) != attrValue {
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t.Fatalf("Attribute binary value decryption error %s != %s %v", string(plainValue), attrValue, err)
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}
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encryptedAttrValue64 := base64.RawURLEncoding.EncodeToString(encryptedAttrValue)
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xattr.Set(encryptedFn, encryptedAttrName2, []byte(encryptedAttrValue64))
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plainValue, err = xattr.Get(plainFn, attrName2)
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if err != nil || string(plainValue) != attrValue {
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t.Fatalf("Attribute base64-encoded value decryption error %s != %s %v", string(plainValue), attrValue, err)
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}
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// Remount with -wpanic=false so gocryptfs does not panics when it sees
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// the broken xattrs
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test_helpers.UnmountPanic(test_helpers.DefaultPlainDir)
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test_helpers.MountOrExit(test_helpers.DefaultCipherDir, test_helpers.DefaultPlainDir, "-zerokey", "-wpanic=false")
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brokenVals := []string{
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"111",
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"raw-test-long-block123",
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"raw-test-long-block123-xyz11111111111111111111111111111111111111",
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"$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$",
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}
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for _, val := range brokenVals {
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xattr.Set(encryptedFn, encryptedAttrName2, []byte(val))
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plainValue, err = xattr.Get(plainFn, attrName2)
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err2, _ := err.(*xattr.Error)
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if err == nil || err2.Err != syscall.EIO {
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t.Fatalf("Incorrect handling of broken data %s %v", string(plainValue), err)
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}
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}
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}
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