Support RTM_DELLINK

This change will allow us to remove the default link in a packetimpact test so
we can reduce indeterministic behaviors as required in https://fxbug.dev/78430.
This will also help with testing #1388.

Updates #578, #1388.

PiperOrigin-RevId: 387896847

5 files changed, 97 insertions, 34 deletions

diff --git a/pkg/sentry/inet/inet.go b/pkg/sentry/inet/inet.go
index 80dda1559..b121fc1b4 100644
--- a/pkg/sentry/inet/inet.go
+++ b/pkg/sentry/inet/inet.go
@@ -27,6 +27,9 @@ type Stack interface {
 	// integers.
 	Interfaces() map[int32]Interface
 
+	// RemoveInterface removes the specified network interface.
+	RemoveInterface(idx int32) error
+
 	// InterfaceAddrs returns all network interface addresses as a mapping from
 	// interface indexes to a slice of associated interface address properties.
 	InterfaceAddrs() map[int32][]InterfaceAddr
diff --git a/pkg/sentry/inet/test_stack.go b/pkg/sentry/inet/test_stack.go
index 218d9dafc..621f47e1f 100644
--- a/pkg/sentry/inet/test_stack.go
+++ b/pkg/sentry/inet/test_stack.go
@@ -45,23 +45,29 @@ func NewTestStack() *TestStack {
 	}
 }
 
-// Interfaces implements Stack.Interfaces.
+// Interfaces implements Stack.
 func (s *TestStack) Interfaces() map[int32]Interface {
 	return s.InterfacesMap
 }
 
-// InterfaceAddrs implements Stack.InterfaceAddrs.
+// RemoveInterface implements Stack.
+func (s *TestStack) RemoveInterface(idx int32) error {
+	delete(s.InterfacesMap, idx)
+	return nil
+}
+
+// InterfaceAddrs implements Stack.
 func (s *TestStack) InterfaceAddrs() map[int32][]InterfaceAddr {
 	return s.InterfaceAddrsMap
 }
 
-// AddInterfaceAddr implements Stack.AddInterfaceAddr.
+// AddInterfaceAddr implements Stack.
 func (s *TestStack) AddInterfaceAddr(idx int32, addr InterfaceAddr) error {
 	s.InterfaceAddrsMap[idx] = append(s.InterfaceAddrsMap[idx], addr)
 	return nil
 }
 
-// RemoveInterfaceAddr implements Stack.RemoveInterfaceAddr.
+// RemoveInterfaceAddr implements Stack.
 func (s *TestStack) RemoveInterfaceAddr(idx int32, addr InterfaceAddr) error {
 	interfaceAddrs, ok := s.InterfaceAddrsMap[idx]
 	if !ok {
@@ -79,94 +85,94 @@ func (s *TestStack) RemoveInterfaceAddr(idx int32, addr InterfaceAddr) error {
 	return nil
 }
 
-// SupportsIPv6 implements Stack.SupportsIPv6.
+// SupportsIPv6 implements Stack.
 func (s *TestStack) SupportsIPv6() bool {
 	return s.SupportsIPv6Flag
 }
 
-// TCPReceiveBufferSize implements Stack.TCPReceiveBufferSize.
+// TCPReceiveBufferSize implements Stack.
 func (s *TestStack) TCPReceiveBufferSize() (TCPBufferSize, error) {
 	return s.TCPRecvBufSize, nil
 }
 
-// SetTCPReceiveBufferSize implements Stack.SetTCPReceiveBufferSize.
+// SetTCPReceiveBufferSize implements Stack.
 func (s *TestStack) SetTCPReceiveBufferSize(size TCPBufferSize) error {
 	s.TCPRecvBufSize = size
 	return nil
 }
 
-// TCPSendBufferSize implements Stack.TCPSendBufferSize.
+// TCPSendBufferSize implements Stack.
 func (s *TestStack) TCPSendBufferSize() (TCPBufferSize, error) {
 	return s.TCPSendBufSize, nil
 }
 
-// SetTCPSendBufferSize implements Stack.SetTCPSendBufferSize.
+// SetTCPSendBufferSize implements Stack.
 func (s *TestStack) SetTCPSendBufferSize(size TCPBufferSize) error {
 	s.TCPSendBufSize = size
 	return nil
 }
 
-// TCPSACKEnabled implements Stack.TCPSACKEnabled.
+// TCPSACKEnabled implements Stack.
 func (s *TestStack) TCPSACKEnabled() (bool, error) {
 	return s.TCPSACKFlag, nil
 }
 
-// SetTCPSACKEnabled implements Stack.SetTCPSACKEnabled.
+// SetTCPSACKEnabled implements Stack.
 func (s *TestStack) SetTCPSACKEnabled(enabled bool) error {
 	s.TCPSACKFlag = enabled
 	return nil
 }
 
-// TCPRecovery implements Stack.TCPRecovery.
+// TCPRecovery implements Stack.
 func (s *TestStack) TCPRecovery() (TCPLossRecovery, error) {
 	return s.Recovery, nil
 }
 
-// SetTCPRecovery implements Stack.SetTCPRecovery.
+// SetTCPRecovery implements Stack.
 func (s *TestStack) SetTCPRecovery(recovery TCPLossRecovery) error {
 	s.Recovery = recovery
 	return nil
 }
 
-// Statistics implements inet.Stack.Statistics.
+// Statistics implements Stack.
 func (s *TestStack) Statistics(stat interface{}, arg string) error {
 	return nil
 }
 
-// RouteTable implements Stack.RouteTable.
+// RouteTable implements Stack.
 func (s *TestStack) RouteTable() []Route {
 	return s.RouteList
 }
 
-// Resume implements Stack.Resume.
+// Resume implements Stack.
 func (s *TestStack) Resume() {}
 
-// RegisteredEndpoints implements inet.Stack.RegisteredEndpoints.
+// RegisteredEndpoints implements Stack.
 func (s *TestStack) RegisteredEndpoints() []stack.TransportEndpoint {
 	return nil
 }
 
-// CleanupEndpoints implements inet.Stack.CleanupEndpoints.
+// CleanupEndpoints implements Stack.
 func (s *TestStack) CleanupEndpoints() []stack.TransportEndpoint {
 	return nil
 }
 
-// RestoreCleanupEndpoints implements inet.Stack.RestoreCleanupEndpoints.
+// RestoreCleanupEndpoints implements Stack.
 func (s *TestStack) RestoreCleanupEndpoints([]stack.TransportEndpoint) {}
 
-// SetForwarding implements inet.Stack.SetForwarding.
+// SetForwarding implements Stack.
 func (s *TestStack) SetForwarding(protocol tcpip.NetworkProtocolNumber, enable bool) error {
 	s.IPForwarding = enable
 	return nil
 }
 
-// PortRange implements inet.Stack.PortRange.
+// PortRange implements Stack.
 func (*TestStack) PortRange() (uint16, uint16) {
 	// Use the default Linux values per net/ipv4/af_inet.c:inet_init_net().
 	return 32768, 28232
 }
 
-// SetPortRange implements inet.Stack.SetPortRange.
+// SetPortRange implements Stack.
 func (*TestStack) SetPortRange(start uint16, end uint16) error {
 	// No-op.
 	return nil
diff --git a/pkg/sentry/socket/hostinet/stack.go b/pkg/sentry/socket/hostinet/stack.go
index 7a4e78a5f..61111ac6c 100644
--- a/pkg/sentry/socket/hostinet/stack.go
+++ b/pkg/sentry/socket/hostinet/stack.go
@@ -309,6 +309,11 @@ func (s *Stack) Interfaces() map[int32]inet.Interface {
 	return interfaces
 }
 
+// RemoveInterface implements inet.Stack.RemoveInterface.
+func (*Stack) RemoveInterface(int32) error {
+	return linuxerr.EACCES
+}
+
 // InterfaceAddrs implements inet.Stack.InterfaceAddrs.
 func (s *Stack) InterfaceAddrs() map[int32][]inet.InterfaceAddr {
 	addrs := make(map[int32][]inet.InterfaceAddr)
@@ -319,12 +324,12 @@ func (s *Stack) InterfaceAddrs() map[int32][]inet.InterfaceAddr {
 }
 
 // AddInterfaceAddr implements inet.Stack.AddInterfaceAddr.
-func (s *Stack) AddInterfaceAddr(int32, inet.InterfaceAddr) error {
+func (*Stack) AddInterfaceAddr(int32, inet.InterfaceAddr) error {
 	return linuxerr.EACCES
 }
 
 // RemoveInterfaceAddr implements inet.Stack.RemoveInterfaceAddr.
-func (s *Stack) RemoveInterfaceAddr(int32, inet.InterfaceAddr) error {
+func (*Stack) RemoveInterfaceAddr(int32, inet.InterfaceAddr) error {
 	return linuxerr.EACCES
 }
 
@@ -339,7 +344,7 @@ func (s *Stack) TCPReceiveBufferSize() (inet.TCPBufferSize, error) {
 }
 
 // SetTCPReceiveBufferSize implements inet.Stack.SetTCPReceiveBufferSize.
-func (s *Stack) SetTCPReceiveBufferSize(size inet.TCPBufferSize) error {
+func (*Stack) SetTCPReceiveBufferSize(inet.TCPBufferSize) error {
 	return linuxerr.EACCES
 }
 
@@ -349,7 +354,7 @@ func (s *Stack) TCPSendBufferSize() (inet.TCPBufferSize, error) {
 }
 
 // SetTCPSendBufferSize implements inet.Stack.SetTCPSendBufferSize.
-func (s *Stack) SetTCPSendBufferSize(size inet.TCPBufferSize) error {
+func (*Stack) SetTCPSendBufferSize(inet.TCPBufferSize) error {
 	return linuxerr.EACCES
 }
 
@@ -359,7 +364,7 @@ func (s *Stack) TCPSACKEnabled() (bool, error) {
 }
 
 // SetTCPSACKEnabled implements inet.Stack.SetTCPSACKEnabled.
-func (s *Stack) SetTCPSACKEnabled(bool) error {
+func (*Stack) SetTCPSACKEnabled(bool) error {
 	return linuxerr.EACCES
 }
 
@@ -369,7 +374,7 @@ func (s *Stack) TCPRecovery() (inet.TCPLossRecovery, error) {
 }
 
 // SetTCPRecovery implements inet.Stack.SetTCPRecovery.
-func (s *Stack) SetTCPRecovery(inet.TCPLossRecovery) error {
+func (*Stack) SetTCPRecovery(inet.TCPLossRecovery) error {
 	return linuxerr.EACCES
 }
 
@@ -470,19 +475,19 @@ func (s *Stack) RouteTable() []inet.Route {
 }
 
 // Resume implements inet.Stack.Resume.
-func (s *Stack) Resume() {}
+func (*Stack) Resume() {}
 
 // RegisteredEndpoints implements inet.Stack.RegisteredEndpoints.
-func (s *Stack) RegisteredEndpoints() []stack.TransportEndpoint { return nil }
+func (*Stack) RegisteredEndpoints() []stack.TransportEndpoint { return nil }
 
 // CleanupEndpoints implements inet.Stack.CleanupEndpoints.
-func (s *Stack) CleanupEndpoints() []stack.TransportEndpoint { return nil }
+func (*Stack) CleanupEndpoints() []stack.TransportEndpoint { return nil }
 
 // RestoreCleanupEndpoints implements inet.Stack.RestoreCleanupEndpoints.
-func (s *Stack) RestoreCleanupEndpoints([]stack.TransportEndpoint) {}
+func (*Stack) RestoreCleanupEndpoints([]stack.TransportEndpoint) {}
 
 // SetForwarding implements inet.Stack.SetForwarding.
-func (s *Stack) SetForwarding(tcpip.NetworkProtocolNumber, bool) error {
+func (*Stack) SetForwarding(tcpip.NetworkProtocolNumber, bool) error {
 	return linuxerr.EACCES
 }
 
@@ -493,6 +498,6 @@ func (*Stack) PortRange() (uint16, uint16) {
 }
 
 // SetPortRange implements inet.Stack.SetPortRange.
-func (*Stack) SetPortRange(start uint16, end uint16) error {
+func (*Stack) SetPortRange(uint16, uint16) error {
 	return linuxerr.EACCES
 }
diff --git a/pkg/sentry/socket/netlink/route/protocol.go b/pkg/sentry/socket/netlink/route/protocol.go
index 86f6419dc..d526acb73 100644
--- a/pkg/sentry/socket/netlink/route/protocol.go
+++ b/pkg/sentry/socket/netlink/route/protocol.go
@@ -161,6 +161,47 @@ func (p *Protocol) getLink(ctx context.Context, msg *netlink.Message, ms *netlin
 	return nil
 }
 
+// delLink handles RTM_DELLINK requests.
+func (p *Protocol) delLink(ctx context.Context, msg *netlink.Message, ms *netlink.MessageSet) *syserr.Error {
+	stack := inet.StackFromContext(ctx)
+	if stack == nil {
+		// No network stack.
+		return syserr.ErrProtocolNotSupported
+	}
+
+	var ifinfomsg linux.InterfaceInfoMessage
+	attrs, ok := msg.GetData(&ifinfomsg)
+	if !ok {
+		return syserr.ErrInvalidArgument
+	}
+	if ifinfomsg.Index == 0 {
+		// The index is unspecified, search by the interface name.
+		ahdr, value, _, ok := attrs.ParseFirst()
+		if !ok {
+			return syserr.ErrInvalidArgument
+		}
+		switch ahdr.Type {
+		case linux.IFLA_IFNAME:
+			if len(value) < 1 {
+				return syserr.ErrInvalidArgument
+			}
+			ifname := string(value[:len(value)-1])
+			for idx, ifa := range stack.Interfaces() {
+				if ifname == ifa.Name {
+					ifinfomsg.Index = idx
+					break
+				}
+			}
+		default:
+			return syserr.ErrInvalidArgument
+		}
+		if ifinfomsg.Index == 0 {
+			return syserr.ErrNoDevice
+		}
+	}
+	return syserr.FromError(stack.RemoveInterface(ifinfomsg.Index))
+}
+
 // addNewLinkMessage appends RTM_NEWLINK message for the given interface into
 // the message set.
 func addNewLinkMessage(ms *netlink.MessageSet, idx int32, i inet.Interface) {
@@ -537,6 +578,8 @@ func (p *Protocol) ProcessMessage(ctx context.Context, msg *netlink.Message, ms
 		switch hdr.Type {
 		case linux.RTM_GETLINK:
 			return p.getLink(ctx, msg, ms)
+		case linux.RTM_DELLINK:
+			return p.delLink(ctx, msg, ms)
 		case linux.RTM_GETROUTE:
 			return p.dumpRoutes(ctx, msg, ms)
 		case linux.RTM_NEWADDR:
diff --git a/pkg/sentry/socket/netstack/stack.go b/pkg/sentry/socket/netstack/stack.go
index 0fd0ad32c..208ab9909 100644
--- a/pkg/sentry/socket/netstack/stack.go
+++ b/pkg/sentry/socket/netstack/stack.go
@@ -71,6 +71,12 @@ func (s *Stack) Interfaces() map[int32]inet.Interface {
 	return is
 }
 
+// RemoveInterface implements inet.Stack.RemoveInterface.
+func (s *Stack) RemoveInterface(idx int32) error {
+	nic := tcpip.NICID(idx)
+	return syserr.TranslateNetstackError(s.Stack.RemoveNIC(nic)).ToError()
+}
+
 // InterfaceAddrs implements inet.Stack.InterfaceAddrs.
 func (s *Stack) InterfaceAddrs() map[int32][]inet.InterfaceAddr {
 	nicAddrs := make(map[int32][]inet.InterfaceAddr)