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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 hostinet
import (
"fmt"
"io/ioutil"
"os"
"strings"
"syscall"
"gvisor.googlesource.com/gvisor/pkg/binary"
"gvisor.googlesource.com/gvisor/pkg/log"
"gvisor.googlesource.com/gvisor/pkg/sentry/context"
"gvisor.googlesource.com/gvisor/pkg/sentry/inet"
"gvisor.googlesource.com/gvisor/pkg/sentry/usermem"
"gvisor.googlesource.com/gvisor/pkg/syserror"
)
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
supportsIPv6 bool
tcpRecvBufSize inet.TCPBufferSize
tcpSendBufSize inet.TCPBufferSize
tcpSACKEnabled bool
}
// 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 := 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")
}
s.tcpSACKEnabled = false
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 false")
}
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 != syscall.RTM_NEWLINK {
continue
}
if len(link.Data) < syscall.SizeofIfInfomsg {
return fmt.Errorf("RTM_GETLINK returned RTM_NEWLINK message with invalid data length (%d bytes, expected at least %d bytes)", len(link.Data), syscall.SizeofIfInfomsg)
}
var ifinfo syscall.IfInfomsg
binary.Unmarshal(link.Data[:syscall.SizeofIfInfomsg], usermem.ByteOrder, &ifinfo)
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 syscall.IFLA_ADDRESS:
inetIF.Addr = attr.Value
case syscall.IFLA_IFNAME:
inetIF.Name = string(attr.Value[:len(attr.Value)-1])
}
}
interfaces[ifinfo.Index] = inetIF
}
for _, addr := range addrs {
if addr.Header.Type != syscall.RTM_NEWADDR {
continue
}
if len(addr.Data) < syscall.SizeofIfAddrmsg {
return fmt.Errorf("RTM_GETADDR returned RTM_NEWADDR message with invalid data length (%d bytes, expected at least %d bytes)", len(addr.Data), syscall.SizeofIfAddrmsg)
}
var ifaddr syscall.IfAddrmsg
binary.Unmarshal(addr.Data[:syscall.SizeofIfAddrmsg], usermem.ByteOrder, &ifaddr)
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 syscall.IFA_ADDRESS:
inetAddr.Addr = attr.Value
}
}
interfaceAddrs[int32(ifaddr.Index)] = append(interfaceAddrs[int32(ifaddr.Index)], inetAddr)
}
return nil
}
func addHostInterfaces(s *Stack) error {
links, err := doNetlinkRouteRequest(syscall.RTM_GETLINK)
if err != nil {
return fmt.Errorf("RTM_GETLINK failed: %v", err)
}
addrs, err := doNetlinkRouteRequest(syscall.RTM_GETADDR)
if err != nil {
return fmt.Errorf("RTM_GETADDR failed: %v", err)
}
return ExtractHostInterfaces(links, addrs, s.interfaces, s.interfaceAddrs)
}
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 {
return s.interfaces
}
// InterfaceAddrs implements inet.Stack.InterfaceAddrs.
func (s *Stack) InterfaceAddrs() map[int32][]inet.InterfaceAddr {
return s.interfaceAddrs
}
// 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 (s *Stack) SetTCPReceiveBufferSize(size inet.TCPBufferSize) error {
return syserror.EACCES
}
// TCPSendBufferSize implements inet.Stack.TCPSendBufferSize.
func (s *Stack) TCPSendBufferSize() (inet.TCPBufferSize, error) {
return s.tcpSendBufSize, nil
}
// SetTCPSendBufferSize implements inet.Stack.SetTCPSendBufferSize.
func (s *Stack) SetTCPSendBufferSize(size inet.TCPBufferSize) error {
return syserror.EACCES
}
// TCPSACKEnabled implements inet.Stack.TCPSACKEnabled.
func (s *Stack) TCPSACKEnabled() (bool, error) {
return s.tcpSACKEnabled, nil
}
// SetTCPSACKEnabled implements inet.Stack.SetTCPSACKEnabled.
func (s *Stack) SetTCPSACKEnabled(enabled bool) error {
return syserror.EACCES
}
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