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// Copyright 2018 The gVisor Authors.
//
// 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 hostinet
import (
"encoding/binary"
"fmt"
"io"
"io/ioutil"
"os"
"reflect"
"strconv"
"strings"
"syscall"
"time"
"golang.org/x/sys/unix"
"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/marshal/primitive"
"gvisor.dev/gvisor/pkg/sentry/inet"
"gvisor.dev/gvisor/pkg/syserr"
"gvisor.dev/gvisor/pkg/tcpip"
"gvisor.dev/gvisor/pkg/tcpip/stack"
"gvisor.dev/gvisor/pkg/usermem"
)
var defaultRecvBufSize = inet.TCPBufferSize{
Min: 4096,
Default: 87380,
Max: 6291456,
}
var defaultSendBufSize = inet.TCPBufferSize{
Min: 4096,
Default: 16384,
Max: 4194304,
}
// Stack implements inet.Stack for host sockets.
type Stack struct {
// Stack is immutable.
interfaces map[int32]*inet.Interface
interfaceAddrs map[int32][]inet.InterfaceAddr
routes []inet.Route
supportsIPv6 bool
tcpRecovery inet.TCPLossRecovery
tcpRecvBufSize inet.TCPBufferSize
tcpSendBufSize inet.TCPBufferSize
tcpSACKEnabled bool
netDevFile *os.File
netSNMPFile *os.File
}
// Destroy implements inet.Stack.Destroy.
func (*Stack) Destroy() {
}
// NewStack returns an empty Stack containing no configuration.
func NewStack() *Stack {
return &Stack{
interfaces: make(map[int32]*inet.Interface),
interfaceAddrs: make(map[int32][]inet.InterfaceAddr),
}
}
// Configure sets up the stack using the current state of the host network.
func (s *Stack) Configure() error {
if err := addHostInterfaces(s); err != nil {
return err
}
if err := addHostRoutes(s); err != nil {
return err
}
if _, err := os.Stat("/proc/net/if_inet6"); err == nil {
s.supportsIPv6 = true
}
s.tcpRecvBufSize = defaultRecvBufSize
if tcpRMem, err := readTCPBufferSizeFile("/proc/sys/net/ipv4/tcp_rmem"); err == nil {
s.tcpRecvBufSize = tcpRMem
} else {
log.Warningf("Failed to read TCP receive buffer size, using default values")
}
s.tcpSendBufSize = defaultSendBufSize
if tcpWMem, err := readTCPBufferSizeFile("/proc/sys/net/ipv4/tcp_wmem"); err == nil {
s.tcpSendBufSize = tcpWMem
} else {
log.Warningf("Failed to read TCP send buffer size, using default values")
}
// SACK is important for performance and even compatibility, assume it's
// enabled if we can't find the actual value.
s.tcpSACKEnabled = true
if sack, err := ioutil.ReadFile("/proc/sys/net/ipv4/tcp_sack"); err == nil {
s.tcpSACKEnabled = strings.TrimSpace(string(sack)) != "0"
} else {
log.Warningf("Failed to read if TCP SACK if enabled, setting to true")
}
if f, err := os.Open("/proc/net/dev"); err != nil {
log.Warningf("Failed to open /proc/net/dev: %v", err)
} else {
s.netDevFile = f
}
if f, err := os.Open("/proc/net/snmp"); err != nil {
log.Warningf("Failed to open /proc/net/snmp: %v", err)
} else {
s.netSNMPFile = f
}
return nil
}
// ExtractHostInterfaces will populate an interface map and
// interfaceAddrs map with the results of the equivalent
// netlink messages.
func ExtractHostInterfaces(links []syscall.NetlinkMessage, addrs []syscall.NetlinkMessage, interfaces map[int32]*inet.Interface, interfaceAddrs map[int32][]inet.InterfaceAddr) error {
for _, link := range links {
if link.Header.Type != unix.RTM_NEWLINK {
continue
}
if len(link.Data) < unix.SizeofIfInfomsg {
return fmt.Errorf("RTM_GETLINK returned RTM_NEWLINK message with invalid data length (%d bytes, expected at least %d bytes)", len(link.Data), unix.SizeofIfInfomsg)
}
var ifinfo linux.InterfaceInfoMessage
ifinfo.UnmarshalUnsafe(link.Data)
inetIF := inet.Interface{
DeviceType: ifinfo.Type,
Flags: ifinfo.Flags,
}
// Not clearly documented: syscall.ParseNetlinkRouteAttr will check the
// syscall.NetlinkMessage.Header.Type and skip the struct ifinfomsg
// accordingly.
attrs, err := syscall.ParseNetlinkRouteAttr(&link)
if err != nil {
return fmt.Errorf("RTM_GETLINK returned RTM_NEWLINK message with invalid rtattrs: %v", err)
}
for _, attr := range attrs {
switch attr.Attr.Type {
case unix.IFLA_ADDRESS:
inetIF.Addr = attr.Value
case unix.IFLA_IFNAME:
inetIF.Name = string(attr.Value[:len(attr.Value)-1])
}
}
interfaces[ifinfo.Index] = &inetIF
}
for _, addr := range addrs {
if addr.Header.Type != unix.RTM_NEWADDR {
continue
}
if len(addr.Data) < unix.SizeofIfAddrmsg {
return fmt.Errorf("RTM_GETADDR returned RTM_NEWADDR message with invalid data length (%d bytes, expected at least %d bytes)", len(addr.Data), unix.SizeofIfAddrmsg)
}
var ifaddr linux.InterfaceAddrMessage
ifaddr.UnmarshalUnsafe(addr.Data)
inetAddr := inet.InterfaceAddr{
Family: ifaddr.Family,
PrefixLen: ifaddr.PrefixLen,
Flags: ifaddr.Flags,
}
attrs, err := syscall.ParseNetlinkRouteAttr(&addr)
if err != nil {
return fmt.Errorf("RTM_GETADDR returned RTM_NEWADDR message with invalid rtattrs: %v", err)
}
for _, attr := range attrs {
switch attr.Attr.Type {
case unix.IFA_ADDRESS:
inetAddr.Addr = attr.Value
}
}
interfaceAddrs[int32(ifaddr.Index)] = append(interfaceAddrs[int32(ifaddr.Index)], inetAddr)
}
return nil
}
// ExtractHostRoutes populates the given routes slice with the data from the
// host route table.
func ExtractHostRoutes(routeMsgs []syscall.NetlinkMessage) ([]inet.Route, error) {
var routes []inet.Route
for _, routeMsg := range routeMsgs {
if routeMsg.Header.Type != unix.RTM_NEWROUTE {
continue
}
var ifRoute linux.RouteMessage
ifRoute.UnmarshalUnsafe(routeMsg.Data)
inetRoute := inet.Route{
Family: ifRoute.Family,
DstLen: ifRoute.DstLen,
SrcLen: ifRoute.SrcLen,
TOS: ifRoute.TOS,
Table: ifRoute.Table,
Protocol: ifRoute.Protocol,
Scope: ifRoute.Scope,
Type: ifRoute.Type,
Flags: ifRoute.Flags,
}
// Not clearly documented: syscall.ParseNetlinkRouteAttr will check the
// syscall.NetlinkMessage.Header.Type and skip the struct rtmsg
// accordingly.
attrs, err := syscall.ParseNetlinkRouteAttr(&routeMsg)
if err != nil {
return nil, fmt.Errorf("RTM_GETROUTE returned RTM_NEWROUTE message with invalid rtattrs: %v", err)
}
for _, attr := range attrs {
switch attr.Attr.Type {
case unix.RTA_DST:
inetRoute.DstAddr = attr.Value
case unix.RTA_SRC:
inetRoute.SrcAddr = attr.Value
case unix.RTA_GATEWAY:
inetRoute.GatewayAddr = attr.Value
case unix.RTA_OIF:
expected := int(binary.Size(inetRoute.OutputInterface))
if len(attr.Value) != expected {
return nil, fmt.Errorf("RTM_GETROUTE returned RTM_NEWROUTE message with invalid attribute data length (%d bytes, expected %d bytes)", len(attr.Value), expected)
}
var outputIF primitive.Int32
outputIF.UnmarshalUnsafe(attr.Value)
inetRoute.OutputInterface = int32(outputIF)
}
}
routes = append(routes, inetRoute)
}
return routes, nil
}
func addHostInterfaces(s *Stack) error {
links, err := doNetlinkRouteRequest(unix.RTM_GETLINK)
if err != nil {
return fmt.Errorf("RTM_GETLINK failed: %v", err)
}
addrs, err := doNetlinkRouteRequest(unix.RTM_GETADDR)
if err != nil {
return fmt.Errorf("RTM_GETADDR failed: %v", err)
}
if err := ExtractHostInterfaces(links, addrs, s.interfaces, s.interfaceAddrs); err != nil {
return err
}
// query interface features for each of the host interfaces.
if err := queryInterfaceFeatures(s.interfaces); err != nil {
return err
}
return nil
}
func addHostRoutes(s *Stack) error {
routes, err := doNetlinkRouteRequest(unix.RTM_GETROUTE)
if err != nil {
return fmt.Errorf("RTM_GETROUTE failed: %v", err)
}
s.routes, err = ExtractHostRoutes(routes)
if err != nil {
return err
}
return nil
}
func doNetlinkRouteRequest(req int) ([]syscall.NetlinkMessage, error) {
data, err := syscall.NetlinkRIB(req, syscall.AF_UNSPEC)
if err != nil {
return nil, err
}
return syscall.ParseNetlinkMessage(data)
}
func readTCPBufferSizeFile(filename string) (inet.TCPBufferSize, error) {
contents, err := ioutil.ReadFile(filename)
if err != nil {
return inet.TCPBufferSize{}, fmt.Errorf("failed to read %s: %v", filename, err)
}
ioseq := usermem.BytesIOSequence(contents)
fields := make([]int32, 3)
if n, err := usermem.CopyInt32StringsInVec(context.Background(), ioseq.IO, ioseq.Addrs, fields, ioseq.Opts); n != ioseq.NumBytes() || err != nil {
return inet.TCPBufferSize{}, fmt.Errorf("failed to parse %s (%q): got %v after %d/%d bytes", filename, contents, err, n, ioseq.NumBytes())
}
return inet.TCPBufferSize{
Min: int(fields[0]),
Default: int(fields[1]),
Max: int(fields[2]),
}, nil
}
// Interfaces implements inet.Stack.Interfaces.
func (s *Stack) Interfaces() map[int32]inet.Interface {
interfaces := make(map[int32]inet.Interface)
for k, v := range s.interfaces {
interfaces[k] = *v
}
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)
for k, v := range s.interfaceAddrs {
addrs[k] = append([]inet.InterfaceAddr(nil), v...)
}
return addrs
}
// AddInterfaceAddr implements inet.Stack.AddInterfaceAddr.
func (*Stack) AddInterfaceAddr(int32, inet.InterfaceAddr) error {
return linuxerr.EACCES
}
// RemoveInterfaceAddr implements inet.Stack.RemoveInterfaceAddr.
func (*Stack) RemoveInterfaceAddr(int32, inet.InterfaceAddr) error {
return linuxerr.EACCES
}
// SupportsIPv6 implements inet.Stack.SupportsIPv6.
func (s *Stack) SupportsIPv6() bool {
return s.supportsIPv6
}
// TCPReceiveBufferSize implements inet.Stack.TCPReceiveBufferSize.
func (s *Stack) TCPReceiveBufferSize() (inet.TCPBufferSize, error) {
return s.tcpRecvBufSize, nil
}
// SetTCPReceiveBufferSize implements inet.Stack.SetTCPReceiveBufferSize.
func (*Stack) SetTCPReceiveBufferSize(inet.TCPBufferSize) error {
return linuxerr.EACCES
}
// TCPSendBufferSize implements inet.Stack.TCPSendBufferSize.
func (s *Stack) TCPSendBufferSize() (inet.TCPBufferSize, error) {
return s.tcpSendBufSize, nil
}
// SetTCPSendBufferSize implements inet.Stack.SetTCPSendBufferSize.
func (*Stack) SetTCPSendBufferSize(inet.TCPBufferSize) error {
return linuxerr.EACCES
}
// TCPSACKEnabled implements inet.Stack.TCPSACKEnabled.
func (s *Stack) TCPSACKEnabled() (bool, error) {
return s.tcpSACKEnabled, nil
}
// SetTCPSACKEnabled implements inet.Stack.SetTCPSACKEnabled.
func (*Stack) SetTCPSACKEnabled(bool) error {
return linuxerr.EACCES
}
// TCPRecovery implements inet.Stack.TCPRecovery.
func (s *Stack) TCPRecovery() (inet.TCPLossRecovery, error) {
return s.tcpRecovery, nil
}
// SetTCPRecovery implements inet.Stack.SetTCPRecovery.
func (*Stack) SetTCPRecovery(inet.TCPLossRecovery) error {
return linuxerr.EACCES
}
// getLine reads one line from proc file, with specified prefix.
// The last argument, withHeader, specifies if it contains line header.
func getLine(f *os.File, prefix string, withHeader bool) string {
data := make([]byte, 4096)
if _, err := f.Seek(0, 0); err != nil {
return ""
}
if _, err := io.ReadFull(f, data); err != io.ErrUnexpectedEOF {
return ""
}
prefix = prefix + ":"
lines := strings.Split(string(data), "\n")
for _, l := range lines {
l = strings.TrimSpace(l)
if strings.HasPrefix(l, prefix) {
if withHeader {
withHeader = false
continue
}
return l
}
}
return ""
}
func toSlice(i any) []uint64 {
v := reflect.Indirect(reflect.ValueOf(i))
return v.Slice(0, v.Len()).Interface().([]uint64)
}
// Statistics implements inet.Stack.Statistics.
func (s *Stack) Statistics(stat any, arg string) error {
var (
snmpTCP bool
rawLine string
sliceStat []uint64
)
switch stat.(type) {
case *inet.StatDev:
if s.netDevFile == nil {
return fmt.Errorf("/proc/net/dev is not opened for hostinet")
}
rawLine = getLine(s.netDevFile, arg, false /* with no header */)
case *inet.StatSNMPIP, *inet.StatSNMPICMP, *inet.StatSNMPICMPMSG, *inet.StatSNMPTCP, *inet.StatSNMPUDP, *inet.StatSNMPUDPLite:
if s.netSNMPFile == nil {
return fmt.Errorf("/proc/net/snmp is not opened for hostinet")
}
rawLine = getLine(s.netSNMPFile, arg, true)
default:
return syserr.ErrEndpointOperation.ToError()
}
if rawLine == "" {
return fmt.Errorf("failed to get raw line")
}
parts := strings.SplitN(rawLine, ":", 2)
if len(parts) != 2 {
return fmt.Errorf("failed to get prefix from: %q", rawLine)
}
sliceStat = toSlice(stat)
fields := strings.Fields(strings.TrimSpace(parts[1]))
if len(fields) != len(sliceStat) {
return fmt.Errorf("failed to parse fields: %q", rawLine)
}
if _, ok := stat.(*inet.StatSNMPTCP); ok {
snmpTCP = true
}
for i := 0; i < len(sliceStat); i++ {
var err error
if snmpTCP && i == 3 {
var tmp int64
// MaxConn field is signed, RFC 2012.
tmp, err = strconv.ParseInt(fields[i], 10, 64)
sliceStat[i] = uint64(tmp) // Convert back to int before use.
} else {
sliceStat[i], err = strconv.ParseUint(fields[i], 10, 64)
}
if err != nil {
return fmt.Errorf("failed to parse field %d from: %q, %v", i, rawLine, err)
}
}
return nil
}
// RouteTable implements inet.Stack.RouteTable.
func (s *Stack) RouteTable() []inet.Route {
return append([]inet.Route(nil), s.routes...)
}
// Pause implements inet.Stack.Pause.
func (*Stack) Pause() {}
// Resume implements inet.Stack.Resume.
func (*Stack) Resume() {}
// RegisteredEndpoints implements inet.Stack.RegisteredEndpoints.
func (*Stack) RegisteredEndpoints() []stack.TransportEndpoint { return nil }
// CleanupEndpoints implements inet.Stack.CleanupEndpoints.
func (*Stack) CleanupEndpoints() []stack.TransportEndpoint { return nil }
// RestoreCleanupEndpoints implements inet.Stack.RestoreCleanupEndpoints.
func (*Stack) RestoreCleanupEndpoints([]stack.TransportEndpoint) {}
// SetForwarding implements inet.Stack.SetForwarding.
func (*Stack) SetForwarding(tcpip.NetworkProtocolNumber, bool) error {
return linuxerr.EACCES
}
// PortRange implements inet.Stack.PortRange.
func (*Stack) 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.
func (*Stack) SetPortRange(uint16, uint16) error {
return linuxerr.EACCES
}
// GROTimeout implements inet.Stack.GROTimeout.
func (s *Stack) GROTimeout(NICID int32) (time.Duration, error) {
return 0, nil
}
// SetGROTimeout implements inet.Stack.SetGROTimeout.
func (s *Stack) SetGROTimeout(NICID int32, timeout time.Duration) error {
// We don't support setting the hostinet GRO timeout.
return linuxerr.EINVAL
}
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