Automated rollback of changelist 336304024

PiperOrigin-RevId: 336339194

2 files changed, 33 insertions, 20 deletions

diff --git a/pkg/sentry/fs/dev/BUILD b/pkg/sentry/fs/dev/BUILD
index 9379a4d7b..6b7b451b8 100644
--- a/pkg/sentry/fs/dev/BUILD
+++ b/pkg/sentry/fs/dev/BUILD
@@ -34,6 +34,7 @@ go_library(
         "//pkg/sentry/socket/netstack",
         "//pkg/syserror",
         "//pkg/tcpip/link/tun",
+        "//pkg/tcpip/network/arp",
         "//pkg/usermem",
         "//pkg/waiter",
     ],
diff --git a/pkg/sentry/fs/dev/net_tun.go b/pkg/sentry/fs/dev/net_tun.go
index 5f8c9b5a2..19ffdec47 100644
--- a/pkg/sentry/fs/dev/net_tun.go
+++ b/pkg/sentry/fs/dev/net_tun.go
@@ -15,6 +15,8 @@
 package dev
 
 import (
+	"fmt"
+
 	"gvisor.dev/gvisor/pkg/abi/linux"
 	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/sentry/arch"
@@ -25,6 +27,7 @@ import (
 	"gvisor.dev/gvisor/pkg/sentry/socket/netstack"
 	"gvisor.dev/gvisor/pkg/syserror"
 	"gvisor.dev/gvisor/pkg/tcpip/link/tun"
+	"gvisor.dev/gvisor/pkg/tcpip/network/arp"
 	"gvisor.dev/gvisor/pkg/usermem"
 	"gvisor.dev/gvisor/pkg/waiter"
 )
@@ -60,7 +63,7 @@ func newNetTunDevice(ctx context.Context, owner fs.FileOwner, mode linux.FileMod
 }
 
 // GetFile implements fs.InodeOperations.GetFile.
-func (iops *netTunInodeOperations) GetFile(ctx context.Context, d *fs.Dirent, flags fs.FileFlags) (*fs.File, error) {
+func (*netTunInodeOperations) GetFile(ctx context.Context, d *fs.Dirent, flags fs.FileFlags) (*fs.File, error) {
 	return fs.NewFile(ctx, d, flags, &netTunFileOperations{}), nil
 }
 
@@ -80,12 +83,12 @@ type netTunFileOperations struct {
 var _ fs.FileOperations = (*netTunFileOperations)(nil)
 
 // Release implements fs.FileOperations.Release.
-func (fops *netTunFileOperations) Release(ctx context.Context) {
-	fops.device.Release(ctx)
+func (n *netTunFileOperations) Release(ctx context.Context) {
+	n.device.Release(ctx)
 }
 
 // Ioctl implements fs.FileOperations.Ioctl.
-func (fops *netTunFileOperations) Ioctl(ctx context.Context, file *fs.File, io usermem.IO, args arch.SyscallArguments) (uintptr, error) {
+func (n *netTunFileOperations) Ioctl(ctx context.Context, file *fs.File, io usermem.IO, args arch.SyscallArguments) (uintptr, error) {
 	request := args[1].Uint()
 	data := args[2].Pointer()
 
@@ -109,16 +112,25 @@ func (fops *netTunFileOperations) Ioctl(ctx context.Context, file *fs.File, io u
 			return 0, err
 		}
 		flags := usermem.ByteOrder.Uint16(req.Data[:])
-		return 0, fops.device.SetIff(stack.Stack, req.Name(), flags)
+		created, err := n.device.SetIff(stack.Stack, req.Name(), flags)
+		if err == nil && created {
+			// Always start with an ARP address for interfaces so they can handle ARP
+			// packets.
+			nicID := n.device.NICID()
+			if err := stack.Stack.AddAddress(nicID, arp.ProtocolNumber, arp.ProtocolAddress); err != nil {
+				panic(fmt.Sprintf("failed to add ARP address after creating new TUN/TAP interface with ID = %d", nicID))
+			}
+		}
+		return 0, err
 
 	case linux.TUNGETIFF:
 		var req linux.IFReq
 
-		copy(req.IFName[:], fops.device.Name())
+		copy(req.IFName[:], n.device.Name())
 
 		// Linux adds IFF_NOFILTER (the same value as IFF_NO_PI unfortunately) when
 		// there is no sk_filter. See __tun_chr_ioctl() in net/drivers/tun.c.
-		flags := fops.device.Flags() | linux.IFF_NOFILTER
+		flags := n.device.Flags() | linux.IFF_NOFILTER
 		usermem.ByteOrder.PutUint16(req.Data[:], flags)
 
 		_, err := req.CopyOut(t, data)
@@ -130,41 +142,41 @@ func (fops *netTunFileOperations) Ioctl(ctx context.Context, file *fs.File, io u
 }
 
 // Write implements fs.FileOperations.Write.
-func (fops *netTunFileOperations) Write(ctx context.Context, file *fs.File, src usermem.IOSequence, offset int64) (int64, error) {
+func (n *netTunFileOperations) Write(ctx context.Context, file *fs.File, src usermem.IOSequence, offset int64) (int64, error) {
 	data := make([]byte, src.NumBytes())
 	if _, err := src.CopyIn(ctx, data); err != nil {
 		return 0, err
 	}
-	return fops.device.Write(data)
+	return n.device.Write(data)
 }
 
 // Read implements fs.FileOperations.Read.
-func (fops *netTunFileOperations) Read(ctx context.Context, file *fs.File, dst usermem.IOSequence, offset int64) (int64, error) {
-	data, err := fops.device.Read()
+func (n *netTunFileOperations) Read(ctx context.Context, file *fs.File, dst usermem.IOSequence, offset int64) (int64, error) {
+	data, err := n.device.Read()
 	if err != nil {
 		return 0, err
 	}
-	n, err := dst.CopyOut(ctx, data)
-	if n > 0 && n < len(data) {
+	bytesCopied, err := dst.CopyOut(ctx, data)
+	if bytesCopied > 0 && bytesCopied < len(data) {
 		// Not an error for partial copying. Packet truncated.
 		err = nil
 	}
-	return int64(n), err
+	return int64(bytesCopied), err
 }
 
 // Readiness implements watier.Waitable.Readiness.
-func (fops *netTunFileOperations) Readiness(mask waiter.EventMask) waiter.EventMask {
-	return fops.device.Readiness(mask)
+func (n *netTunFileOperations) Readiness(mask waiter.EventMask) waiter.EventMask {
+	return n.device.Readiness(mask)
 }
 
 // EventRegister implements watier.Waitable.EventRegister.
-func (fops *netTunFileOperations) EventRegister(e *waiter.Entry, mask waiter.EventMask) {
-	fops.device.EventRegister(e, mask)
+func (n *netTunFileOperations) EventRegister(e *waiter.Entry, mask waiter.EventMask) {
+	n.device.EventRegister(e, mask)
 }
 
 // EventUnregister implements watier.Waitable.EventUnregister.
-func (fops *netTunFileOperations) EventUnregister(e *waiter.Entry) {
-	fops.device.EventUnregister(e)
+func (n *netTunFileOperations) EventUnregister(e *waiter.Entry) {
+	n.device.EventUnregister(e)
 }
 
 // isNetTunSupported returns whether /dev/net/tun device is supported for s.