Check in gVisor.

PiperOrigin-RevId: 194583126
Change-Id: Ica1d8821a90f74e7e745962d71801c598c652463

1 files changed, 90 insertions, 0 deletions

diff --git a/pkg/sentry/fs/host/control.go b/pkg/sentry/fs/host/control.go
new file mode 100644
index 000000000..d2b007ab2
--- /dev/null
+++ b/pkg/sentry/fs/host/control.go
@@ -0,0 +1,90 @@
+// Copyright 2018 Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package host
+
+import (
+	"syscall"
+
+	"gvisor.googlesource.com/gvisor/pkg/sentry/context"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/socket/control"
+	"gvisor.googlesource.com/gvisor/pkg/tcpip/transport/unix"
+)
+
+type scmRights struct {
+	fds []int
+}
+
+func newSCMRights(fds []int) control.SCMRights {
+	return &scmRights{fds}
+}
+
+// Files implements control.SCMRights.Files.
+func (c *scmRights) Files(ctx context.Context, max int) control.RightsFiles {
+	n := max
+	if l := len(c.fds); n > l {
+		n = l
+	}
+
+	rf := control.RightsFiles(fdsToFiles(ctx, c.fds[:n]))
+
+	// Only consume converted FDs (fdsToFiles may convert fewer than n FDs).
+	c.fds = c.fds[len(rf):]
+	return rf
+}
+
+// Clone implements unix.RightsControlMessage.Clone.
+func (c *scmRights) Clone() unix.RightsControlMessage {
+	// Host rights never need to be cloned.
+	return nil
+}
+
+// Release implements unix.RightsControlMessage.Release.
+func (c *scmRights) Release() {
+	for _, fd := range c.fds {
+		syscall.Close(fd)
+	}
+	c.fds = nil
+}
+
+// If an error is encountered, only files created before the error will be
+// returned. This is what Linux does.
+func fdsToFiles(ctx context.Context, fds []int) []*fs.File {
+	files := make([]*fs.File, 0, len(fds))
+	for _, fd := range fds {
+		// Get flags. We do it here because they may be modified
+		// by subsequent functions.
+		fileFlags, _, errno := syscall.Syscall(syscall.SYS_FCNTL, uintptr(fd), syscall.F_GETFL, 0)
+		if errno != 0 {
+			ctx.Warningf("Error retrieving host FD flags: %v", error(errno))
+			break
+		}
+
+		// Create the file backed by hostFD.
+		file, err := NewFile(ctx, fd, fs.FileOwnerFromContext(ctx))
+		if err != nil {
+			ctx.Warningf("Error creating file from host FD: %v", err)
+			break
+		}
+
+		// Set known flags.
+		file.SetFlags(fs.SettableFileFlags{
+			NonBlocking: fileFlags&syscall.O_NONBLOCK != 0,
+		})
+
+		files = append(files, file)
+	}
+	return files
+}