Skip to content

reversesshfs: serve only the mounted directory, add ReadonlyNames #118

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
sylvinus wants to merge 1 commit into
base: master
Choose a base branch
from
Open

reversesshfs: serve only the mounted directory, add ReadonlyNames #118

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
2 changes: 1 addition & 1 deletion go.mod
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,7 @@ require (
github.com/pkg/sftp v1.13.11
github.com/sirupsen/logrus v1.9.4
github.com/urfave/cli/v2 v2.27.7
golang.org/x/sys v0.47.0
)

require (
Expand All @@ -14,5 +15,4 @@ require (
github.com/russross/blackfriday/v2 v2.1.0 // indirect
github.com/xrash/smetrics v0.0.0-20240521201337-686a1a2994c1 // indirect
golang.org/x/crypto v0.54.0 // indirect
golang.org/x/sys v0.47.0 // indirect
)
40 changes: 31 additions & 9 deletions pkg/reversesshfs/reversesshfs.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -40,6 +40,10 @@ type ReverseSSHFS struct {
sshCmd *exec.Cmd
opensshSftpServerCmd *exec.Cmd
SSHFSAdditionalArgs []string

// ReadonlyNames makes a path read-only when any of its components is one of these names
// (compared case-insensitively). Requires DriverBuiltin on Linux or macOS.
ReadonlyNames []string
}

func (rsf *ReverseSSHFS) Prepare() error {
Expand Down Expand Up @@ -158,6 +162,10 @@ func (rsf *ReverseSSHFS) Start() error {
case DriverBuiltin, DriverOpensshSftpServer:
// NOP
case "", DriverAuto:
if len(rsf.ReadonlyNames) > 0 {
driver = DriverBuiltin
break
}
var err error
driver, opensshSftpServerBinary, err = DetectDriver(opensshSftpServerBinary)
if err != nil {
Expand All @@ -167,7 +175,13 @@ func (rsf *ReverseSSHFS) Start() error {
default:
return fmt.Errorf("unknown driver %q", driver)
}
var builtinSftpServer *sftp.Server
if len(rsf.ReadonlyNames) > 0 && driver != DriverBuiltin {
return fmt.Errorf("ReadonlyNames requires driver %q, got %q", DriverBuiltin, driver)
}
var (
builtinSftpServer interface{ Serve() error }
rooted *rootedHandlers
)
switch driver {
case DriverBuiltin:
stdinPipe, err := rsf.sshCmd.StdinPipe()
Expand All @@ -182,15 +196,20 @@ func (rsf *ReverseSSHFS) Start() error {
ReadCloser: stdoutPipe,
WriteCloser: stdinPipe,
}
var sftpOpts []sftp.ServerOption
if rsf.Readonly {
sftpOpts = append(sftpOpts, sftp.ReadOnly())
if runtime.GOOS == "windows" {
if len(rsf.ReadonlyNames) > 0 {
return errors.New("ReadonlyNames is not supported on Windows")
}
var sftpOpts []sftp.ServerOption
if rsf.Readonly {
sftpOpts = append(sftpOpts, sftp.ReadOnly())
}
// NOTE: sftp.NewServer doesn't support specifying the root.
// https://github.com/pkg/sftp/pull/238
builtinSftpServer, err = sftp.NewServer(stdio, sftpOpts...)
} else {
builtinSftpServer, rooted, err = newRootedServer(stdio, rsf.LocalPath, rsf.Readonly, rsf.ReadonlyNames)
}
// NOTE: sftp.NewServer doesn't support specifying the root.
// https://github.com/pkg/sftp/pull/238
//
// TODO: use sftp.NewRequestServer with custom handlers to mitigate potential vulnerabilities.
builtinSftpServer, err = sftp.NewServer(stdio, sftpOpts...)
if err != nil {
return err
}
Expand Down Expand Up @@ -234,6 +253,9 @@ func (rsf *ReverseSSHFS) Start() error {
switch driver {
case DriverBuiltin:
go func() {
if rooted != nil {
defer rooted.Close()
}
if srvErr := builtinSftpServer.Serve(); srvErr != nil {
if errors.Is(srvErr, io.EOF) {
logrus.WithError(srvErr).Debugf("sftp server for %v exited with EOF (negligible)", rsf.LocalPath)
Expand Down
Loading