From cc5cfce4c6c9df1a44433681b87d411a67b09b28 Mon Sep 17 00:00:00 2001
From: Ghanan Gowripalan <ghanan@google.com>
Date: Mon, 16 Nov 2020 14:32:57 -0800
Subject: Remove ARP address workaround

- Make AddressableEndpoint optional for NetworkEndpoint.
Not all NetworkEndpoints need to support addressing (e.g. ARP), so
AddressableEndpoint should only be implemented for protocols that
support addressing such as IPv4 and IPv6.

With this change, tcpip.ErrNotSupported will be returned by the stack
when attempting to modify addresses on a network endpoint that does
not support addressing.

Now that packets are fully handled at the network layer, and (with this
change) addresses are optional for network endpoints, we no longer need
the workaround for ARP where a fake ARP address was added to each NIC
that performs ARP so that packets would be delivered to the ARP layer.

PiperOrigin-RevId: 342722547
---
 pkg/sentry/devices/tundev/BUILD     |  1 -
 pkg/sentry/devices/tundev/tundev.go | 14 +-------------
 pkg/sentry/fs/dev/BUILD             |  1 -
 pkg/sentry/fs/dev/net_tun.go        | 14 +-------------
 4 files changed, 2 insertions(+), 28 deletions(-)

(limited to 'pkg/sentry')

diff --git a/pkg/sentry/devices/tundev/BUILD b/pkg/sentry/devices/tundev/BUILD
index 14a8bf9cd..71c59287c 100644
--- a/pkg/sentry/devices/tundev/BUILD
+++ b/pkg/sentry/devices/tundev/BUILD
@@ -17,7 +17,6 @@ go_library(
         "//pkg/sentry/vfs",
         "//pkg/syserror",
         "//pkg/tcpip/link/tun",
-        "//pkg/tcpip/network/arp",
         "//pkg/usermem",
         "//pkg/waiter",
     ],
diff --git a/pkg/sentry/devices/tundev/tundev.go b/pkg/sentry/devices/tundev/tundev.go
index ff5d49fbd..d8f4e1d35 100644
--- a/pkg/sentry/devices/tundev/tundev.go
+++ b/pkg/sentry/devices/tundev/tundev.go
@@ -16,8 +16,6 @@
 package tundev
 
 import (
-	"fmt"
-
 	"gvisor.dev/gvisor/pkg/abi/linux"
 	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/sentry/arch"
@@ -28,7 +26,6 @@ import (
 	"gvisor.dev/gvisor/pkg/sentry/vfs"
 	"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"
 )
@@ -91,16 +88,7 @@ func (fd *tunFD) Ioctl(ctx context.Context, uio usermem.IO, args arch.SyscallArg
 			return 0, err
 		}
 		flags := usermem.ByteOrder.Uint16(req.Data[:])
-		created, err := fd.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 := fd.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
+		return 0, fd.device.SetIff(stack.Stack, req.Name(), flags)
 
 	case linux.TUNGETIFF:
 		var req linux.IFReq
diff --git a/pkg/sentry/fs/dev/BUILD b/pkg/sentry/fs/dev/BUILD
index 6b7b451b8..9379a4d7b 100644
--- a/pkg/sentry/fs/dev/BUILD
+++ b/pkg/sentry/fs/dev/BUILD
@@ -34,7 +34,6 @@ 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 19ffdec47..5227ef652 100644
--- a/pkg/sentry/fs/dev/net_tun.go
+++ b/pkg/sentry/fs/dev/net_tun.go
@@ -15,8 +15,6 @@
 package dev
 
 import (
-	"fmt"
-
 	"gvisor.dev/gvisor/pkg/abi/linux"
 	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/sentry/arch"
@@ -27,7 +25,6 @@ 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"
 )
@@ -112,16 +109,7 @@ func (n *netTunFileOperations) Ioctl(ctx context.Context, file *fs.File, io user
 			return 0, err
 		}
 		flags := usermem.ByteOrder.Uint16(req.Data[:])
-		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
+		return 0, n.device.SetIff(stack.Stack, req.Name(), flags)
 
 	case linux.TUNGETIFF:
 		var req linux.IFReq
-- 
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