1 files changed, 33 insertions, 22 deletions

diff --git a/runsc/fsgofer/fsgofer.go b/runsc/fsgofer/fsgofer.go
index 7c4d2b94e..ed8b02cf0 100644
--- a/runsc/fsgofer/fsgofer.go
+++ b/runsc/fsgofer/fsgofer.go
@@ -54,6 +54,7 @@ const (
 	regular fileType = iota
 	directory
 	symlink
+	socket
 	unknown
 )
 
@@ -66,6 +67,8 @@ func (f fileType) String() string {
 		return "directory"
 	case symlink:
 		return "symlink"
+	case socket:
+		return "socket"
 	}
 	return "unknown"
 }
@@ -82,6 +85,9 @@ type Config struct {
 
 	// PanicOnWrite panics on attempts to write to RO mounts.
 	PanicOnWrite bool
+
+	// HostUDS signals whether the gofer can mount a host's UDS.
+	HostUDS bool
 }
 
 type attachPoint struct {
@@ -119,35 +125,31 @@ func NewAttachPoint(prefix string, c Config) (p9.Attacher, error) {
 
 // Attach implements p9.Attacher.
 func (a *attachPoint) Attach() (p9.File, error) {
-	// dirFD (1st argument) is ignored because 'prefix' is always absolute.
-	stat, err := statAt(-1, a.prefix)
-	if err != nil {
-		return nil, fmt.Errorf("stat file %q, err: %v", a.prefix, err)
-	}
-	mode := syscall.O_RDWR
-	if a.conf.ROMount || (stat.Mode&syscall.S_IFMT) == syscall.S_IFDIR {
-		mode = syscall.O_RDONLY
+	a.attachedMu.Lock()
+	defer a.attachedMu.Unlock()
+
+	if a.attached {
+		return nil, fmt.Errorf("attach point already attached, prefix: %s", a.prefix)
 	}
 
-	// Open the root directory.
-	f, err := fd.Open(a.prefix, openFlags|mode, 0)
+	f, err := openAnyFile(a.prefix, func(mode int) (*fd.FD, error) {
+		return fd.Open(a.prefix, openFlags|mode, 0)
+	})
 	if err != nil {
-		return nil, fmt.Errorf("unable to open file %q, err: %v", a.prefix, err)
+		return nil, fmt.Errorf("unable to open %q: %v", a.prefix, err)
 	}
 
-	a.attachedMu.Lock()
-	defer a.attachedMu.Unlock()
-	if a.attached {
-		f.Close()
-		return nil, fmt.Errorf("attach point already attached, prefix: %s", a.prefix)
+	stat, err := stat(f.FD())
+	if err != nil {
+		return nil, fmt.Errorf("unable to stat %q: %v", a.prefix, err)
 	}
 
-	rv, err := newLocalFile(a, f, a.prefix, stat)
+	lf, err := newLocalFile(a, f, a.prefix, stat)
 	if err != nil {
-		return nil, err
+		return nil, fmt.Errorf("unable to create localFile %q: %v", a.prefix, err)
 	}
 	a.attached = true
-	return rv, nil
+	return lf, nil
 }
 
 // makeQID returns a unique QID for the given stat buffer.
@@ -295,7 +297,7 @@ func openAnyFile(path string, fn func(mode int) (*fd.FD, error)) (*fd.FD, error)
 	return file, nil
 }
 
-func getSupportedFileType(stat syscall.Stat_t) (fileType, error) {
+func getSupportedFileType(stat syscall.Stat_t, permitSocket bool) (fileType, error) {
 	var ft fileType
 	switch stat.Mode & syscall.S_IFMT {
 	case syscall.S_IFREG:
@@ -304,6 +306,11 @@ func getSupportedFileType(stat syscall.Stat_t) (fileType, error) {
 		ft = directory
 	case syscall.S_IFLNK:
 		ft = symlink
+	case syscall.S_IFSOCK:
+		if !permitSocket {
+			return unknown, syscall.EPERM
+		}
+		ft = socket
 	default:
 		return unknown, syscall.EPERM
 	}
@@ -311,7 +318,7 @@ func getSupportedFileType(stat syscall.Stat_t) (fileType, error) {
 }
 
 func newLocalFile(a *attachPoint, file *fd.FD, path string, stat syscall.Stat_t) (*localFile, error) {
-	ft, err := getSupportedFileType(stat)
+	ft, err := getSupportedFileType(stat, a.conf.HostUDS)
 	if err != nil {
 		return nil, err
 	}
@@ -1026,7 +1033,11 @@ func (l *localFile) Flush() error {
 
 // Connect implements p9.File.
 func (l *localFile) Connect(p9.ConnectFlags) (*fd.FD, error) {
-	return nil, syscall.ECONNREFUSED
+	// Check to see if the CLI option has been set to allow the UDS mount.
+	if !l.attachPoint.conf.HostUDS {
+		return nil, syscall.ECONNREFUSED
+	}
+	return fd.DialUnix(l.hostPath)
 }
 
 // Close implements p9.File.