Complete pipe support on overlayfs

Get/Set pipe size and ioctl support were missing from
overlayfs. It required moving the pipe.Sizer interface
to fs so that overlay could get access.

Fixes #318

PiperOrigin-RevId: 255511125

9 files changed, 62 insertions, 11 deletions

diff --git a/pkg/sentry/fs/ashmem/area.go b/pkg/sentry/fs/ashmem/area.go
index e1971f91c..3b8d6ca89 100644
--- a/pkg/sentry/fs/ashmem/area.go
+++ b/pkg/sentry/fs/ashmem/area.go
@@ -139,7 +139,7 @@ func (a *Area) ConfigureMMap(ctx context.Context, file *fs.File, opts *memmap.MM
 }
 
 // Ioctl implements fs.FileOperations.Ioctl.
-func (a *Area) Ioctl(ctx context.Context, io usermem.IO, args arch.SyscallArguments) (uintptr, error) {
+func (a *Area) Ioctl(ctx context.Context, _ *fs.File, io usermem.IO, args arch.SyscallArguments) (uintptr, error) {
 	// Switch on ioctl request.
 	switch args[1].Uint() {
 	case linux.AshmemSetNameIoctl:
diff --git a/pkg/sentry/fs/binder/binder.go b/pkg/sentry/fs/binder/binder.go
index acd5d7164..eef54d787 100644
--- a/pkg/sentry/fs/binder/binder.go
+++ b/pkg/sentry/fs/binder/binder.go
@@ -162,7 +162,7 @@ func (bp *Proc) ConfigureMMap(ctx context.Context, file *fs.File, opts *memmap.M
 // Ioctl implements fs.FileOperations.Ioctl.
 //
 // TODO(b/30946773): Implement.
-func (bp *Proc) Ioctl(ctx context.Context, io usermem.IO, args arch.SyscallArguments) (uintptr, error) {
+func (bp *Proc) Ioctl(ctx context.Context, _ *fs.File, io usermem.IO, args arch.SyscallArguments) (uintptr, error) {
 	// Switch on ioctl request.
 	switch uint32(args[1].Int()) {
 	case linux.BinderVersionIoctl:
diff --git a/pkg/sentry/fs/file_operations.go b/pkg/sentry/fs/file_operations.go
index 2c5bd1b19..d86f5bf45 100644
--- a/pkg/sentry/fs/file_operations.go
+++ b/pkg/sentry/fs/file_operations.go
@@ -155,5 +155,16 @@ type FileOperations interface {
 	// refer.
 	//
 	// Preconditions: The AddressSpace (if any) that io refers to is activated.
-	Ioctl(ctx context.Context, io usermem.IO, args arch.SyscallArguments) (uintptr, error)
+	Ioctl(ctx context.Context, file *File, io usermem.IO, args arch.SyscallArguments) (uintptr, error)
+}
+
+// FifoSizer is an interface for setting and getting the size of a pipe.
+type FifoSizer interface {
+	// FifoSize returns the pipe capacity in bytes.
+	FifoSize(ctx context.Context, file *File) (int64, error)
+
+	// SetFifoSize sets the new pipe capacity in bytes.
+	//
+	// The new size is returned (which may be capped).
+	SetFifoSize(size int64) (int64, error)
 }
diff --git a/pkg/sentry/fs/file_overlay.go b/pkg/sentry/fs/file_overlay.go
index 29e5618f4..c6cbd5631 100644
--- a/pkg/sentry/fs/file_overlay.go
+++ b/pkg/sentry/fs/file_overlay.go
@@ -397,9 +397,49 @@ func (f *overlayFileOperations) UnstableAttr(ctx context.Context, file *File) (U
 	return f.lower.UnstableAttr(ctx)
 }
 
-// Ioctl implements fs.FileOperations.Ioctl and always returns ENOTTY.
-func (*overlayFileOperations) Ioctl(ctx context.Context, io usermem.IO, args arch.SyscallArguments) (uintptr, error) {
-	return 0, syserror.ENOTTY
+// Ioctl implements fs.FileOperations.Ioctl.
+func (f *overlayFileOperations) Ioctl(ctx context.Context, overlayFile *File, io usermem.IO, args arch.SyscallArguments) (uintptr, error) {
+	f.upperMu.Lock()
+	defer f.upperMu.Unlock()
+
+	if f.upper == nil {
+		// It's possible that ioctl changes the file. Since we don't know all
+		// possible ioctls, only allow them to propagate to the upper. Triggering a
+		// copy up on any ioctl would be too drastic. In the future, it can have a
+		// list of ioctls that are safe to send to lower and a list that triggers a
+		// copy up.
+		return 0, syserror.ENOTTY
+	}
+	return f.upper.FileOperations.Ioctl(ctx, f.upper, io, args)
+}
+
+// FifoSize implements FifoSizer.FifoSize.
+func (f *overlayFileOperations) FifoSize(ctx context.Context, overlayFile *File) (rv int64, err error) {
+	err = f.onTop(ctx, overlayFile, func(file *File, ops FileOperations) error {
+		sz, ok := ops.(FifoSizer)
+		if !ok {
+			return syserror.EINVAL
+		}
+		rv, err = sz.FifoSize(ctx, file)
+		return err
+	})
+	return
+}
+
+// SetFifoSize implements FifoSizer.SetFifoSize.
+func (f *overlayFileOperations) SetFifoSize(size int64) (rv int64, err error) {
+	f.upperMu.Lock()
+	defer f.upperMu.Unlock()
+
+	if f.upper == nil {
+		// Named pipes cannot be copied up and changes to the lower are prohibited.
+		return 0, syserror.EINVAL
+	}
+	sz, ok := f.upper.FileOperations.(FifoSizer)
+	if !ok {
+		return 0, syserror.EINVAL
+	}
+	return sz.SetFifoSize(size)
 }
 
 // readdirEntries returns a sorted map of directory entries from the
diff --git a/pkg/sentry/fs/fsutil/file.go b/pkg/sentry/fs/fsutil/file.go
index d7ddc038b..626b9126a 100644
--- a/pkg/sentry/fs/fsutil/file.go
+++ b/pkg/sentry/fs/fsutil/file.go
@@ -219,7 +219,7 @@ func GenericConfigureMMap(file *fs.File, m memmap.Mappable, opts *memmap.MMapOpt
 type FileNoIoctl struct{}
 
 // Ioctl implements fs.FileOperations.Ioctl.
-func (FileNoIoctl) Ioctl(ctx context.Context, io usermem.IO, args arch.SyscallArguments) (uintptr, error) {
+func (FileNoIoctl) Ioctl(context.Context, *fs.File, usermem.IO, arch.SyscallArguments) (uintptr, error) {
 	return 0, syserror.ENOTTY
 }
 
diff --git a/pkg/sentry/fs/host/tty.go b/pkg/sentry/fs/host/tty.go
index 0ceedb200..2526412a4 100644
--- a/pkg/sentry/fs/host/tty.go
+++ b/pkg/sentry/fs/host/tty.go
@@ -114,7 +114,7 @@ func (t *TTYFileOperations) Release() {
 }
 
 // Ioctl implements fs.FileOperations.Ioctl.
-func (t *TTYFileOperations) Ioctl(ctx context.Context, io usermem.IO, args arch.SyscallArguments) (uintptr, error) {
+func (t *TTYFileOperations) Ioctl(ctx context.Context, _ *fs.File, io usermem.IO, args arch.SyscallArguments) (uintptr, error) {
 	// Ignore arg[0].  This is the real FD:
 	fd := t.fileOperations.iops.fileState.FD()
 	ioctl := args[1].Uint64()
diff --git a/pkg/sentry/fs/inotify.go b/pkg/sentry/fs/inotify.go
index 41238f3fa..c7f4e2d13 100644
--- a/pkg/sentry/fs/inotify.go
+++ b/pkg/sentry/fs/inotify.go
@@ -202,7 +202,7 @@ func (i *Inotify) UnstableAttr(ctx context.Context, file *File) (UnstableAttr, e
 }
 
 // Ioctl implements fs.FileOperations.Ioctl.
-func (i *Inotify) Ioctl(ctx context.Context, io usermem.IO, args arch.SyscallArguments) (uintptr, error) {
+func (i *Inotify) Ioctl(ctx context.Context, _ *File, io usermem.IO, args arch.SyscallArguments) (uintptr, error) {
 	switch args[1].Int() {
 	case linux.FIONREAD:
 		i.evMu.Lock()
diff --git a/pkg/sentry/fs/tty/master.go b/pkg/sentry/fs/tty/master.go
index 54dd3d6b7..92ec1ca18 100644
--- a/pkg/sentry/fs/tty/master.go
+++ b/pkg/sentry/fs/tty/master.go
@@ -144,7 +144,7 @@ func (mf *masterFileOperations) Write(ctx context.Context, _ *fs.File, src userm
 }
 
 // Ioctl implements fs.FileOperations.Ioctl.
-func (mf *masterFileOperations) Ioctl(ctx context.Context, io usermem.IO, args arch.SyscallArguments) (uintptr, error) {
+func (mf *masterFileOperations) Ioctl(ctx context.Context, _ *fs.File, io usermem.IO, args arch.SyscallArguments) (uintptr, error) {
 	switch cmd := args[1].Uint(); cmd {
 	case linux.FIONREAD: // linux.FIONREAD == linux.TIOCINQ
 		// Get the number of bytes in the output queue read buffer.
diff --git a/pkg/sentry/fs/tty/slave.go b/pkg/sentry/fs/tty/slave.go
index 2d68978dd..e30266404 100644
--- a/pkg/sentry/fs/tty/slave.go
+++ b/pkg/sentry/fs/tty/slave.go
@@ -128,7 +128,7 @@ func (sf *slaveFileOperations) Write(ctx context.Context, _ *fs.File, src userme
 }
 
 // Ioctl implements fs.FileOperations.Ioctl.
-func (sf *slaveFileOperations) Ioctl(ctx context.Context, io usermem.IO, args arch.SyscallArguments) (uintptr, error) {
+func (sf *slaveFileOperations) Ioctl(ctx context.Context, _ *fs.File, io usermem.IO, args arch.SyscallArguments) (uintptr, error) {
 	switch cmd := args[1].Uint(); cmd {
 	case linux.FIONREAD: // linux.FIONREAD == linux.TIOCINQ
 		// Get the number of bytes in the input queue read buffer.