Pass NEWLINK netlink commands to network stacks

The NEWLINK commands contains many properties and here is no reason to have
another abstract interface between the Sentry and network stacks.

PiperOrigin-RevId: 627916629

pkg/sentry/socket/netstack/BUILD

@@ -39,6 +39,7 @@ go_library(
         "//pkg/sentry/kernel/time",
         "//pkg/sentry/socket",
         "//pkg/sentry/socket/netfilter",
+        "//pkg/sentry/socket/netlink/nlmsg",
         "//pkg/sentry/vfs",
         "//pkg/sync",
         "//pkg/syserr",

pkg/sentry/socket/netstack/stack.go

@@ -18,10 +18,12 @@ import (
 	"fmt"
 
 	"gvisor.dev/gvisor/pkg/abi/linux"
+	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/errors/linuxerr"
 	"gvisor.dev/gvisor/pkg/log"
 	"gvisor.dev/gvisor/pkg/refs"
 	"gvisor.dev/gvisor/pkg/sentry/inet"
+	"gvisor.dev/gvisor/pkg/sentry/socket/netlink/nlmsg"
 	"gvisor.dev/gvisor/pkg/syserr"
 	"gvisor.dev/gvisor/pkg/tcpip"
 	"gvisor.dev/gvisor/pkg/tcpip/header"
@@ -99,6 +101,64 @@ func (s *Stack) RemoveInterface(idx int32) error {
 	return syserr.TranslateNetstackError(s.Stack.RemoveNIC(nic)).ToError()
 }
 
+// SetInterface implements inet.Stack.SetInterface.
+func (s *Stack) SetInterface(ctx context.Context, msg *nlmsg.Message) *syserr.Error {
+	var ifinfomsg linux.InterfaceInfoMessage
+	attrs, ok := msg.GetData(&ifinfomsg)
+	if !ok {
+		return syserr.ErrInvalidArgument
+	}
+	for !attrs.Empty() {
+		// The index is unspecified, search by the interface name.
+		ahdr, value, rest, ok := attrs.ParseFirst()
+		if !ok {
+			return syserr.ErrInvalidArgument
+		}
+		attrs = rest
+		switch ahdr.Type {
+		case linux.IFLA_IFNAME:
+			if len(value) < 1 {
+				return syserr.ErrInvalidArgument
+			}
+			if ifinfomsg.Index != 0 {
+				// Device name changing isn't supported yet.
+				return syserr.ErrNotSupported
+			}
+			ifname := string(value[:len(value)-1])
+			for idx, ifa := range s.Interfaces() {
+				if ifname == ifa.Name {
+					ifinfomsg.Index = idx
+					break
+				}
+			}
+		default:
+			ctx.Warningf("unexpected attribute: %x", ahdr.Type)
+			return syserr.ErrNotSupported
+		}
+	}
+	if ifinfomsg.Index == 0 {
+		return syserr.ErrNoDevice
+	}
+
+	flags := msg.Header().Flags
+	if flags&(linux.NLM_F_EXCL|linux.NLM_F_REPLACE) != 0 {
+		return syserr.ErrExists
+	}
+
+	if ifinfomsg.Flags != 0 || ifinfomsg.Change != 0 {
+		if ifinfomsg.Change & ^uint32(linux.IFF_UP) != 0 {
+			ctx.Warningf("Unsupported ifi_change flags: %x", ifinfomsg.Change)
+			return syserr.ErrInvalidArgument
+		}
+		if ifinfomsg.Flags & ^uint32(linux.IFF_UP) != 0 {
+			ctx.Warningf("Unsupported ifi_flags: %x", ifinfomsg.Change)
+			return syserr.ErrInvalidArgument
+		}
+		// Netstack interfaces are always up.
+	}
+	return nil
+}
+
 // InterfaceAddrs implements inet.Stack.InterfaceAddrs.
 func (s *Stack) InterfaceAddrs() map[int32][]inet.InterfaceAddr {
 	nicAddrs := make(map[int32][]inet.InterfaceAddr)