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// Copyright 2018 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package boot
import (
"fmt"
"math/rand"
"net"
"syscall"
"gvisor.googlesource.com/gvisor/pkg/log"
"gvisor.googlesource.com/gvisor/pkg/tcpip"
"gvisor.googlesource.com/gvisor/pkg/tcpip/link/fdbased"
"gvisor.googlesource.com/gvisor/pkg/tcpip/link/loopback"
"gvisor.googlesource.com/gvisor/pkg/tcpip/link/sniffer"
"gvisor.googlesource.com/gvisor/pkg/tcpip/network/arp"
"gvisor.googlesource.com/gvisor/pkg/tcpip/network/ipv4"
"gvisor.googlesource.com/gvisor/pkg/tcpip/network/ipv6"
"gvisor.googlesource.com/gvisor/pkg/tcpip/stack"
"gvisor.googlesource.com/gvisor/pkg/urpc"
)
// Network exposes methods that can be used to configure a network stack.
type Network struct {
Stack *stack.Stack
}
// Route represents a route in the network stack.
type Route struct {
Destination net.IP
Mask net.IPMask
Gateway net.IP
}
// DefaultRoute represents a catch all route to the default gateway.
type DefaultRoute struct {
Route Route
Name string
}
// FDBasedLink configures an fd-based link.
type FDBasedLink struct {
Name string
MTU int
Addresses []net.IP
Routes []Route
}
// LoopbackLink configures a loopback li nk.
type LoopbackLink struct {
Name string
Addresses []net.IP
Routes []Route
}
// CreateLinksAndRoutesArgs are arguments to CreateLinkAndRoutes.
type CreateLinksAndRoutesArgs struct {
// FilePayload contains the fds associated with the FDBasedLinks. The
// two slices must have the same length.
urpc.FilePayload
LoopbackLinks []LoopbackLink
FDBasedLinks []FDBasedLink
DefaultGateway DefaultRoute
}
// Empty returns true if route hasn't been set.
func (r *Route) Empty() bool {
return r.Destination == nil && r.Mask == nil && r.Gateway == nil
}
func (r *Route) toTcpipRoute(id tcpip.NICID) tcpip.Route {
return tcpip.Route{
Destination: ipToAddress(r.Destination),
Gateway: ipToAddress(r.Gateway),
Mask: ipToAddress(net.IP(r.Mask)),
NIC: id,
}
}
// CreateLinksAndRoutes creates links and routes in a network stack. It should
// only be called once.
func (n *Network) CreateLinksAndRoutes(args *CreateLinksAndRoutesArgs, _ *struct{}) error {
if len(args.FilePayload.Files) != len(args.FDBasedLinks) {
return fmt.Errorf("FilePayload must be same length at FDBasedLinks")
}
var nicID tcpip.NICID
nicids := make(map[string]tcpip.NICID)
// Collect routes from all links.
var routes []tcpip.Route
// Loopback normally appear before other interfaces.
for _, link := range args.LoopbackLinks {
nicID++
nicids[link.Name] = nicID
linkEP := loopback.New()
log.Infof("Enabling loopback interface %q with id %d on addresses %+v", link.Name, nicID, link.Addresses)
if err := n.createNICWithAddrs(nicID, link.Name, linkEP, link.Addresses); err != nil {
return err
}
// Collect the routes from this link.
for _, r := range link.Routes {
routes = append(routes, r.toTcpipRoute(nicID))
}
}
for i, link := range args.FDBasedLinks {
nicID++
nicids[link.Name] = nicID
// Copy the underlying FD.
oldFD := args.FilePayload.Files[i].Fd()
newFD, err := syscall.Dup(int(oldFD))
if err != nil {
return fmt.Errorf("failed to dup FD %v: %v", oldFD, err)
}
linkEP := fdbased.New(&fdbased.Options{
FD: newFD,
MTU: uint32(link.MTU),
ChecksumOffload: false,
EthernetHeader: true,
Address: tcpip.LinkAddress(generateRndMac()),
})
log.Infof("Enabling interface %q with id %d on addresses %+v", link.Name, nicID, link.Addresses)
if err := n.createNICWithAddrs(nicID, link.Name, linkEP, link.Addresses); err != nil {
return err
}
// Collect the routes from this link.
for _, r := range link.Routes {
routes = append(routes, r.toTcpipRoute(nicID))
}
}
if !args.DefaultGateway.Route.Empty() {
nicID, ok := nicids[args.DefaultGateway.Name]
if !ok {
return fmt.Errorf("invalid interface name %q for default route", args.DefaultGateway.Name)
}
routes = append(routes, args.DefaultGateway.Route.toTcpipRoute(nicID))
}
log.Infof("Setting routes %+v", routes)
n.Stack.SetRouteTable(routes)
return nil
}
// createNICWithAddrs creates a NIC in the network stack and adds the given
// addresses.
func (n *Network) createNICWithAddrs(id tcpip.NICID, name string, linkEP tcpip.LinkEndpointID, addrs []net.IP) error {
if err := n.Stack.CreateNamedNIC(id, name, sniffer.New(linkEP)); err != nil {
return fmt.Errorf("CreateNamedNIC(%v, %v, %v) failed: %v", id, name, linkEP, err)
}
// Always start with an arp address for the NIC.
if err := n.Stack.AddAddress(id, arp.ProtocolNumber, arp.ProtocolAddress); err != nil {
return fmt.Errorf("AddAddress(%v, %v, %v) failed: %v", id, arp.ProtocolNumber, arp.ProtocolAddress, err)
}
for _, addr := range addrs {
proto, tcpipAddr := ipToAddressAndProto(addr)
if err := n.Stack.AddAddress(id, proto, tcpipAddr); err != nil {
return fmt.Errorf("AddAddress(%v, %v, %v) failed: %v", id, proto, tcpipAddr, err)
}
}
return nil
}
// ipToAddressAndProto converts IP to tcpip.Address and a protocol number.
//
// Note: don't use 'len(ip)' to determine IP version because length is always 16.
func ipToAddressAndProto(ip net.IP) (tcpip.NetworkProtocolNumber, tcpip.Address) {
if i4 := ip.To4(); i4 != nil {
return ipv4.ProtocolNumber, tcpip.Address(i4)
}
return ipv6.ProtocolNumber, tcpip.Address(ip)
}
// ipToAddress converts IP to tcpip.Address, ignoring the protocol.
func ipToAddress(ip net.IP) tcpip.Address {
_, addr := ipToAddressAndProto(ip)
return addr
}
// generateRndMac returns a random local MAC address.
// Copied from eth_random_addr() (include/linux/etherdevice.h)
func generateRndMac() net.HardwareAddr {
mac := make(net.HardwareAddr, 6)
rand.Read(mac)
mac[0] &^= 0x1 // clear multicast bit
mac[0] |= 0x2 // set local assignment bit (IEEE802)
return mac
}
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