Merge release-20200907.0-157-gca3087472 (automated)

2 files changed, 92 insertions, 0 deletions

diff --git a/pkg/sentry/fsimpl/proc/proc_state_autogen.go b/pkg/sentry/fsimpl/proc/proc_state_autogen.go
index 1a13f066a..60a5644f3 100644
--- a/pkg/sentry/fsimpl/proc/proc_state_autogen.go
+++ b/pkg/sentry/fsimpl/proc/proc_state_autogen.go
@@ -1376,6 +1376,35 @@ func (x *tcpMemData) StateLoad(m state.Source) {
 	m.LoadWait(2, &x.stack)
 }
 
+func (x *ipForwarding) StateTypeName() string {
+	return "pkg/sentry/fsimpl/proc.ipForwarding"
+}
+
+func (x *ipForwarding) StateFields() []string {
+	return []string{
+		"DynamicBytesFile",
+		"stack",
+		"enabled",
+	}
+}
+
+func (x *ipForwarding) beforeSave() {}
+
+func (x *ipForwarding) StateSave(m state.Sink) {
+	x.beforeSave()
+	m.Save(0, &x.DynamicBytesFile)
+	m.Save(1, &x.stack)
+	m.Save(2, &x.enabled)
+}
+
+func (x *ipForwarding) afterLoad() {}
+
+func (x *ipForwarding) StateLoad(m state.Source) {
+	m.Load(0, &x.DynamicBytesFile)
+	m.LoadWait(1, &x.stack)
+	m.Load(2, &x.enabled)
+}
+
 func init() {
 	state.Register((*fdDirInodeRefs)(nil))
 	state.Register((*fdInfoDirInodeRefs)(nil))
@@ -1425,4 +1454,5 @@ func init() {
 	state.Register((*tcpSackData)(nil))
 	state.Register((*tcpRecoveryData)(nil))
 	state.Register((*tcpMemData)(nil))
+	state.Register((*ipForwarding)(nil))
 }
diff --git a/pkg/sentry/fsimpl/proc/tasks_sys.go b/pkg/sentry/fsimpl/proc/tasks_sys.go
index 9e0966efe..a3ffbb15e 100644
--- a/pkg/sentry/fsimpl/proc/tasks_sys.go
+++ b/pkg/sentry/fsimpl/proc/tasks_sys.go
@@ -27,6 +27,7 @@ import (
 	"gvisor.dev/gvisor/pkg/sentry/vfs"
 	"gvisor.dev/gvisor/pkg/sync"
 	"gvisor.dev/gvisor/pkg/syserror"
+	"gvisor.dev/gvisor/pkg/tcpip/network/ipv4"
 	"gvisor.dev/gvisor/pkg/usermem"
 )
 
@@ -67,6 +68,7 @@ func (fs *filesystem) newSysNetDir(root *auth.Credentials, k *kernel.Kernel) *ke
 				"tcp_rmem":     fs.newDentry(root, fs.NextIno(), 0644, &tcpMemData{stack: stack, dir: tcpRMem}),
 				"tcp_sack":     fs.newDentry(root, fs.NextIno(), 0644, &tcpSackData{stack: stack}),
 				"tcp_wmem":     fs.newDentry(root, fs.NextIno(), 0644, &tcpMemData{stack: stack, dir: tcpWMem}),
+				"ip_forward":   fs.newDentry(root, fs.NextIno(), 0444, &ipForwarding{stack: stack}),
 
 				// The following files are simple stubs until they are implemented in
 				// netstack, most of these files are configuration related. We use the
@@ -354,3 +356,63 @@ func (d *tcpMemData) writeSizeLocked(size inet.TCPBufferSize) error {
 		panic(fmt.Sprintf("unknown tcpMemFile type: %v", d.dir))
 	}
 }
+
+// ipForwarding implements vfs.WritableDynamicBytesSource for
+// /proc/sys/net/ipv4/ip_forwarding.
+//
+// +stateify savable
+type ipForwarding struct {
+	kernfs.DynamicBytesFile
+
+	stack   inet.Stack `state:"wait"`
+	enabled *bool
+}
+
+var _ vfs.WritableDynamicBytesSource = (*ipForwarding)(nil)
+
+// Generate implements vfs.DynamicBytesSource.Generate.
+func (ipf *ipForwarding) Generate(ctx context.Context, buf *bytes.Buffer) error {
+	if ipf.enabled == nil {
+		enabled := ipf.stack.Forwarding(ipv4.ProtocolNumber)
+		ipf.enabled = &enabled
+	}
+
+	val := "0\n"
+	if *ipf.enabled {
+		// Technically, this is not quite compatible with Linux. Linux stores these
+		// as an integer, so if you write "2" into tcp_sack, you should get 2 back.
+		// Tough luck.
+		val = "1\n"
+	}
+	buf.WriteString(val)
+
+	return nil
+}
+
+// Write implements vfs.WritableDynamicBytesSource.Write.
+func (ipf *ipForwarding) Write(ctx context.Context, src usermem.IOSequence, offset int64) (int64, error) {
+	if offset != 0 {
+		// No need to handle partial writes thus far.
+		return 0, syserror.EINVAL
+	}
+	if src.NumBytes() == 0 {
+		return 0, nil
+	}
+
+	// Limit input size so as not to impact performance if input size is large.
+	src = src.TakeFirst(usermem.PageSize - 1)
+
+	var v int32
+	n, err := usermem.CopyInt32StringInVec(ctx, src.IO, src.Addrs, &v, src.Opts)
+	if err != nil {
+		return 0, err
+	}
+	if ipf.enabled == nil {
+		ipf.enabled = new(bool)
+	}
+	*ipf.enabled = v != 0
+	if err := ipf.stack.SetForwarding(ipv4.ProtocolNumber, *ipf.enabled); err != nil {
+		return 0, err
+	}
+	return n, nil
+}