From abf7ebcd38e8c2750f4542f29115140bb2b44a9b Mon Sep 17 00:00:00 2001
From: Nayana Bidari <nybidari@google.com>
Date: Thu, 27 Feb 2020 10:59:32 -0800
Subject: Internal change.

PiperOrigin-RevId: 297638665
---
 pkg/sentry/socket/netstack/netstack.go | 40 ++++++++++++++++++++++++++++------
 pkg/tcpip/transport/packet/endpoint.go | 21 +++++++++++++++++-
 2 files changed, 53 insertions(+), 8 deletions(-)

(limited to 'pkg')

diff --git a/pkg/sentry/socket/netstack/netstack.go b/pkg/sentry/socket/netstack/netstack.go
index e187276c5..48c268bfa 100644
--- a/pkg/sentry/socket/netstack/netstack.go
+++ b/pkg/sentry/socket/netstack/netstack.go
@@ -712,14 +712,40 @@ func (s *SocketOperations) Connect(t *kernel.Task, sockaddr []byte, blocking boo
 // Bind implements the linux syscall bind(2) for sockets backed by
 // tcpip.Endpoint.
 func (s *SocketOperations) Bind(t *kernel.Task, sockaddr []byte) *syserr.Error {
-	addr, family, err := AddressAndFamily(sockaddr)
-	if err != nil {
-		return err
-	}
-	if err := s.checkFamily(family, true /* exact */); err != nil {
-		return err
+	family := usermem.ByteOrder.Uint16(sockaddr)
+	var addr tcpip.FullAddress
+
+	// Bind for AF_PACKET requires only family, protocol and ifindex.
+	// In function AddressAndFamily, we check the address length which is
+	// not needed for AF_PACKET bind.
+	if family == linux.AF_PACKET {
+		var a linux.SockAddrLink
+		if len(sockaddr) < sockAddrLinkSize {
+			return syserr.ErrInvalidArgument
+		}
+		binary.Unmarshal(sockaddr[:sockAddrLinkSize], usermem.ByteOrder, &a)
+
+		if a.Protocol != uint16(s.protocol) {
+			return syserr.ErrInvalidArgument
+		}
+
+		addr = tcpip.FullAddress{
+			NIC:  tcpip.NICID(a.InterfaceIndex),
+			Addr: tcpip.Address(a.HardwareAddr[:header.EthernetAddressSize]),
+		}
+	} else {
+		var err *syserr.Error
+		addr, family, err = AddressAndFamily(sockaddr)
+		if err != nil {
+			return err
+		}
+
+		if err = s.checkFamily(family, true /* exact */); err != nil {
+			return err
+		}
+
+		addr = s.mapFamily(addr, family)
 	}
-	addr = s.mapFamily(addr, family)
 
 	// Issue the bind request to the endpoint.
 	return syserr.TranslateNetstackError(s.Endpoint.Bind(addr))
diff --git a/pkg/tcpip/transport/packet/endpoint.go b/pkg/tcpip/transport/packet/endpoint.go
index 5722815e9..09a1cd436 100644
--- a/pkg/tcpip/transport/packet/endpoint.go
+++ b/pkg/tcpip/transport/packet/endpoint.go
@@ -76,6 +76,7 @@ type endpoint struct {
 	sndBufSize int
 	closed     bool
 	stats      tcpip.TransportEndpointStats `state:"nosave"`
+	bound      bool
 }
 
 // NewEndpoint returns a new packet endpoint.
@@ -125,6 +126,7 @@ func (ep *endpoint) Close() {
 	}
 
 	ep.closed = true
+	ep.bound = false
 	ep.waiterQueue.Notify(waiter.EventHUp | waiter.EventErr | waiter.EventIn | waiter.EventOut)
 }
 
@@ -216,7 +218,24 @@ func (ep *endpoint) Bind(addr tcpip.FullAddress) *tcpip.Error {
 	// sll_family (should be AF_PACKET), sll_protocol, and sll_ifindex."
 	// - packet(7).
 
-	return tcpip.ErrNotSupported
+	ep.mu.Lock()
+	defer ep.mu.Unlock()
+
+	if ep.bound {
+		return tcpip.ErrAlreadyBound
+	}
+
+	// Unregister endpoint with all the nics.
+	ep.stack.UnregisterPacketEndpoint(0, ep.netProto, ep)
+
+	// Bind endpoint to receive packets from specific interface.
+	if err := ep.stack.RegisterPacketEndpoint(addr.NIC, ep.netProto, ep); err != nil {
+		return err
+	}
+
+	ep.bound = true
+
+	return nil
 }
 
 // GetLocalAddress implements tcpip.Endpoint.GetLocalAddress.
-- 
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