reverse: make gocryptfs.conf mapping plaintextnames-aware

Only in plaintextnames-mode AND with the config file at the
default location it will be mapped into the mountpoint.

Also adds a test for that.

cli_args.go

@@ -20,6 +20,9 @@ type argContainer struct {
 	// Configuration file name override
 	config             string
 	notifypid, scryptn int
+	// _configCustom is true when the user sets a custom config file name.
+	// This is not a CLI option.
+	_configCustom bool
 }
 
 var flagSet *flag.FlagSet

internal/fusefrontend/args.go

@@ -14,4 +14,8 @@ type Args struct {
 	// Should we chown a file after it has been created?
 	// This only makes sense if (1) allow_other is set and (2) we run as root.
 	PreserveOwner bool
+	// ConfigCustom is true when the user select a non-default config file
+	// location. If it is false, reverse mode maps ".gocryptfs.reverse.conf"
+	// to "gocryptfs.conf" in the plaintext dir.
+	ConfigCustom bool
 }

internal/fusefrontend_reverse/rfs.go

@@ -17,6 +17,7 @@ import (
 	"github.com/rfjakob/gocryptfs/internal/cryptocore"
 	"github.com/rfjakob/gocryptfs/internal/fusefrontend"
 	"github.com/rfjakob/gocryptfs/internal/nametransform"
+	"github.com/rfjakob/gocryptfs/internal/tlog"
 )
 
 const (
@@ -110,13 +111,19 @@ func (rfs *reverseFS) dirIVAttr(relPath string, context *fuse.Context) (*fuse.At
 }
 
 // isDirIV determines if the path points to a gocryptfs.diriv file
-func isDirIV(relPath string) bool {
+func (rfs *reverseFS) isDirIV(relPath string) bool {
+	if rfs.args.PlaintextNames {
+		return false
+	}
 	return filepath.Base(relPath) == nametransform.DirIVFilename
 }
 
 // isNameFile determines if the path points to a gocryptfs.longname.*.name
 // file
-func isNameFile(relPath string) bool {
+func (rfs *reverseFS) isNameFile(relPath string) bool {
+	if rfs.args.PlaintextNames {
+		return false
+	}
 	fileType := nametransform.NameType(filepath.Base(relPath))
 	return fileType == nametransform.LongNameFilename
 }
@@ -161,19 +168,15 @@ func (rfs *reverseFS) GetAttr(relPath string, context *fuse.Context) (*fuse.Attr
 	if relPath == configfile.ConfDefaultName {
 		return rfs.inoAwareStat(configfile.ConfReverseName)
 	}
-	if rfs.isFiltered(relPath) {
-		return nil, fuse.EPERM
-	}
-
 	// Handle virtual files
 	var f nodefs.File
 	var status fuse.Status
 	virtual := false
-	if isDirIV(relPath) {
+	if rfs.isDirIV(relPath) {
 		virtual = true
 		f, status = rfs.newDirIVFile(relPath)
 	}
-	if isNameFile(relPath) {
+	if rfs.isNameFile(relPath) {
 		virtual = true
 		f, status = rfs.newNameFile(relPath)
 	}
@@ -204,7 +207,7 @@ func (rfs *reverseFS) GetAttr(relPath string, context *fuse.Context) (*fuse.Attr
 
 // Access - FUSE call
 func (rfs *reverseFS) Access(relPath string, mode uint32, context *fuse.Context) fuse.Status {
-	if isDirIV(relPath) {
+	if rfs.isDirIV(relPath) {
 		return fuse.OK
 	}
 	if rfs.isFiltered(relPath) {
@@ -223,10 +226,10 @@ func (rfs *reverseFS) Open(relPath string, flags uint32, context *fuse.Context)
 		// gocryptfs.conf maps to .gocryptfs.reverse.conf in the plaintext directory
 		return rfs.loopbackfs.Open(configfile.ConfReverseName, flags, context)
 	}
-	if isDirIV(relPath) {
+	if rfs.isDirIV(relPath) {
 		return rfs.newDirIVFile(relPath)
 	}
-	if isNameFile(relPath) {
+	if rfs.isNameFile(relPath) {
 		return rfs.newNameFile(relPath)
 	}
 	if rfs.isFiltered(relPath) {
@@ -235,6 +238,31 @@ func (rfs *reverseFS) Open(relPath string, flags uint32, context *fuse.Context)
 	return rfs.NewFile(relPath, flags)
 }
 
+func (rfs *reverseFS) openDirPlaintextnames(relPath string, entries []fuse.DirEntry) ([]fuse.DirEntry, fuse.Status) {
+	if relPath != "" || rfs.args.ConfigCustom {
+		return entries, fuse.OK
+	}
+	// We are in the root dir and the default config file name
+	// ".gocryptfs.reverse.conf" is used. We map it to "gocryptfs.conf".
+	dupe := -1
+	status := fuse.OK
+	for i := range entries {
+		if entries[i].Name == configfile.ConfReverseName {
+			entries[i].Name = configfile.ConfDefaultName
+		} else if entries[i].Name == configfile.ConfDefaultName {
+			dupe = i
+		}
+	}
+	if dupe >= 0 {
+		// Warn the user loudly: The gocryptfs.conf_NAME_COLLISION file will
+		// throw ENOENT errors that are hard to miss.
+		tlog.Warn.Printf("The file %s is mapped to %s and shadows another file. Please rename %s in %s .",
+			configfile.ConfReverseName, configfile.ConfDefaultName, configfile.ConfDefaultName, rfs.args.Cipherdir)
+		entries[dupe].Name = "gocryptfs.conf_NAME_COLLISION_" + fmt.Sprintf("%d", cryptocore.RandUint64())
+	}
+	return entries, status
+}
+
 // OpenDir - FUSE readdir call
 func (rfs *reverseFS) OpenDir(cipherPath string, context *fuse.Context) ([]fuse.DirEntry, fuse.Status) {
 	relPath, err := rfs.decryptPath(cipherPath)
@@ -246,6 +274,9 @@ func (rfs *reverseFS) OpenDir(cipherPath string, context *fuse.Context) ([]fuse.
 	if entries == nil {
 		return nil, status
 	}
+	if rfs.args.PlaintextNames {
+		return rfs.openDirPlaintextnames(cipherPath, entries)
+	}
 	// Allocate maximum possible number of virtual files.
 	// If all files have long names we need a virtual ".name" file for each,
 	// plus one for gocryptfs.diriv.

main.go

@@ -155,6 +155,7 @@ func main() {
 			os.Exit(ErrExitInit)
 		}
 		tlog.Info.Printf("Using config file at custom location %s", args.config)
+		args._configCustom = true
 	} else if args.reverse {
 		args.config = filepath.Join(args.cipherdir, configfile.ConfReverseName)
 	} else {

mount.go

@@ -125,6 +125,7 @@ func initFuseFrontend(key []byte, args *argContainer, confFile *configfile.ConfF
 		PlaintextNames: args.plaintextnames,
 		LongNames:      args.longnames,
 		CryptoBackend:  cryptoBackend,
+		ConfigCustom:   args._configCustom,
 	}
 	// confFile is nil when "-zerokey" or "-masterkey" was used
 	if confFile != nil {

tests/reverse/correctness_test.go

@@ -1,6 +1,7 @@
 package reverse_test
 
 import (
+	"io/ioutil"
 	"os"
 	"testing"
 	//"time"
@@ -49,3 +50,17 @@ func TestSymlinks(t *testing.T) {
 		t.Errorf("wrong symlink target: want=%q have=%q", target, actualTarget)
 	}
 }
+
+// .gocryptfs.reverse.conf in the plaintext dir should be visible as
+// gocryptfs.conf
+func TestConfigMapping(t *testing.T) {
+	c := dirB + "/gocryptfs.conf"
+	test_helpers.VerifyExistence(c)
+	data, err := ioutil.ReadFile(c)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(data) == 0 {
+		t.Errorf("empty file")
+	}
+}

tests/reverse/main_test.go

@@ -10,26 +10,38 @@ import (
 
 var dirA, dirB, dirC string
 var x240 string
+var plaintextnames bool
 
 func TestMain(m *testing.M) {
 	x240 = string(bytes.Repeat([]byte("x"), 240))
-	dirA = test_helpers.TmpDir + "/a"
-	dirB = test_helpers.TmpDir + "/b"
-	dirC = test_helpers.TmpDir + "/c"
-	if err := os.Mkdir(dirA, 0700); err != nil {
-		panic(err)
+	var r int
+	for _, plaintextnames = range []bool{false, true} {
+		argsA := []string{"-reverse"}
+		if plaintextnames {
+			argsA = append(argsA, "-plaintextnames")
+		}
+		dirA = test_helpers.InitFS(nil, argsA...)
+		dirB = test_helpers.TmpDir + "/b"
+		dirC = test_helpers.TmpDir + "/c"
+		if err := os.Mkdir(dirB, 0700); err != nil {
+			panic(err)
+		}
+		if err := os.Mkdir(dirC, 0700); err != nil {
+			panic(err)
+		}
+		test_helpers.MountOrExit(dirA, dirB, "-reverse", "-extpass", "echo test")
+		test_helpers.MountOrExit(dirB, dirC, "-extpass", "echo test")
+		r = m.Run()
+		test_helpers.UnmountPanic(dirC)
+		test_helpers.UnmountPanic(dirB)
+
+		os.RemoveAll(dirA)
+		os.RemoveAll(dirB)
+		os.RemoveAll(dirC)
+
+		if r != 0 {
+			os.Exit(r)
+		}
 	}
-	if err := os.Mkdir(dirB, 0700); err != nil {
-		panic(err)
-	}
-	if err := os.Mkdir(dirC, 0700); err != nil {
-		panic(err)
-	}
-	test_helpers.MountOrExit(dirA, dirB, "-zerokey", "-reverse")
-	test_helpers.MountOrExit(dirB, dirC, "-zerokey", "-aessiv")
-	r := m.Run()
-	test_helpers.UnmountPanic(dirC)
-	test_helpers.UnmountPanic(dirB)
-	os.RemoveAll(test_helpers.TmpDir)
 	os.Exit(r)
 }