2 files changed, 75 insertions, 1 deletions
diff --git a/pkg/sentry/fsimpl/proc/proc_state_autogen.go b/pkg/sentry/fsimpl/proc/proc_state_autogen.go
index e297a6257..eca33249c 100644
--- a/pkg/sentry/fsimpl/proc/proc_state_autogen.go
+++ b/pkg/sentry/fsimpl/proc/proc_state_autogen.go
@@ -1173,6 +1173,32 @@ func (x *tcpSackData) StateLoad(m state.Source) {
 	m.Load(2, &x.enabled)
 }
 
+func (x *tcpRecoveryData) StateTypeName() string {
+	return "pkg/sentry/fsimpl/proc.tcpRecoveryData"
+}
+
+func (x *tcpRecoveryData) StateFields() []string {
+	return []string{
+		"DynamicBytesFile",
+		"stack",
+	}
+}
+
+func (x *tcpRecoveryData) beforeSave() {}
+
+func (x *tcpRecoveryData) StateSave(m state.Sink) {
+	x.beforeSave()
+	m.Save(0, &x.DynamicBytesFile)
+	m.Save(1, &x.stack)
+}
+
+func (x *tcpRecoveryData) afterLoad() {}
+
+func (x *tcpRecoveryData) StateLoad(m state.Source) {
+	m.Load(0, &x.DynamicBytesFile)
+	m.LoadWait(1, &x.stack)
+}
+
 func init() {
 	state.Register((*FilesystemType)(nil))
 	state.Register((*subtasksInode)(nil))
@@ -1215,4 +1241,5 @@ func init() {
 	state.Register((*mmapMinAddrData)(nil))
 	state.Register((*hostnameData)(nil))
 	state.Register((*tcpSackData)(nil))
+	state.Register((*tcpRecoveryData)(nil))
 }
diff --git a/pkg/sentry/fsimpl/proc/tasks_sys.go b/pkg/sentry/fsimpl/proc/tasks_sys.go
index 6dac2afa4..b71778128 100644
--- a/pkg/sentry/fsimpl/proc/tasks_sys.go
+++ b/pkg/sentry/fsimpl/proc/tasks_sys.go
@@ -55,7 +55,8 @@ func (fs *filesystem) newSysNetDir(root *auth.Credentials, k *kernel.Kernel) *ke
 	if stack := k.RootNetworkNamespace().Stack(); stack != nil {
 		contents = map[string]*kernfs.Dentry{
 			"ipv4": kernfs.NewStaticDir(root, linux.UNNAMED_MAJOR, fs.devMinor, fs.NextIno(), 0555, map[string]*kernfs.Dentry{
-				"tcp_sack": fs.newDentry(root, fs.NextIno(), 0644, &tcpSackData{stack: stack}),
+				"tcp_recovery": fs.newDentry(root, fs.NextIno(), 0644, &tcpRecoveryData{stack: stack}),
+				"tcp_sack":     fs.newDentry(root, fs.NextIno(), 0644, &tcpSackData{stack: stack}),
 
 				// The following files are simple stubs until they are implemented in
 				// netstack, most of these files are configuration related. We use the
@@ -207,3 +208,49 @@ func (d *tcpSackData) Write(ctx context.Context, src usermem.IOSequence, offset
 	*d.enabled = v != 0
 	return n, d.stack.SetTCPSACKEnabled(*d.enabled)
 }
+
+// tcpRecoveryData implements vfs.WritableDynamicBytesSource for
+// /proc/sys/net/ipv4/tcp_recovery.
+//
+// +stateify savable
+type tcpRecoveryData struct {
+	kernfs.DynamicBytesFile
+
+	stack inet.Stack `state:"wait"`
+}
+
+var _ vfs.WritableDynamicBytesSource = (*tcpRecoveryData)(nil)
+
+// Generate implements vfs.DynamicBytesSource.
+func (d *tcpRecoveryData) Generate(ctx context.Context, buf *bytes.Buffer) error {
+	recovery, err := d.stack.TCPRecovery()
+	if err != nil {
+		return err
+	}
+
+	buf.WriteString(fmt.Sprintf("%d\n", recovery))
+	return nil
+}
+
+func (d *tcpRecoveryData) 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 the amount of memory allocated.
+	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 err := d.stack.SetTCPRecovery(inet.TCPLossRecovery(v)); err != nil {
+		return 0, err
+	}
+	return n, nil
+}