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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 rpcinet
import (
"fmt"
"strings"
"syscall"
"gvisor.googlesource.com/gvisor/pkg/sentry/context"
"gvisor.googlesource.com/gvisor/pkg/sentry/inet"
"gvisor.googlesource.com/gvisor/pkg/sentry/socket/hostinet"
"gvisor.googlesource.com/gvisor/pkg/sentry/socket/rpcinet/conn"
"gvisor.googlesource.com/gvisor/pkg/sentry/socket/rpcinet/notifier"
"gvisor.googlesource.com/gvisor/pkg/sentry/usermem"
"gvisor.googlesource.com/gvisor/pkg/syserror"
"gvisor.googlesource.com/gvisor/pkg/unet"
)
// Stack implements inet.Stack for RPC backed sockets.
type Stack struct {
// We intentionally do not allow these values to be changed to remain
// consistent with the other networking stacks.
interfaces map[int32]inet.Interface
interfaceAddrs map[int32][]inet.InterfaceAddr
supportsIPv6 bool
tcpRecvBufSize inet.TCPBufferSize
tcpSendBufSize inet.TCPBufferSize
tcpSACKEnabled bool
rpcConn *conn.RPCConnection
notifier *notifier.Notifier
}
func readTCPBufferSizeFile(conn *conn.RPCConnection, filename string) (inet.TCPBufferSize, error) {
contents, se := conn.RPCReadFile(filename)
if se != nil {
return inet.TCPBufferSize{}, fmt.Errorf("failed to read %s: %v", filename, se)
}
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
}
// NewStack returns a Stack containing the current state of the host network
// stack.
func NewStack(fd int32) (*Stack, error) {
sock, err := unet.NewSocket(int(fd))
if err != nil {
return nil, err
}
stack := &Stack{
interfaces: make(map[int32]inet.Interface),
interfaceAddrs: make(map[int32][]inet.InterfaceAddr),
rpcConn: conn.NewRPCConnection(sock),
}
var e error
stack.notifier, e = notifier.NewRPCNotifier(stack.rpcConn)
if e != nil {
return nil, e
}
// Load the configuration values from procfs.
tcpRMem, e := readTCPBufferSizeFile(stack.rpcConn, "/proc/sys/net/ipv4/tcp_rmem")
if e != nil {
return nil, e
}
stack.tcpRecvBufSize = tcpRMem
tcpWMem, e := readTCPBufferSizeFile(stack.rpcConn, "/proc/sys/net/ipv4/tcp_wmem")
if e != nil {
return nil, e
}
stack.tcpSendBufSize = tcpWMem
ipv6, se := stack.rpcConn.RPCReadFile("/proc/net/if_inet6")
if len(string(ipv6)) > 0 {
stack.supportsIPv6 = true
}
sackFile := "/proc/sys/net/ipv4/tcp_sack"
sack, se := stack.rpcConn.RPCReadFile(sackFile)
if se != nil {
return nil, fmt.Errorf("failed to read %s: %v", sackFile, se)
}
stack.tcpSACKEnabled = strings.TrimSpace(string(sack)) != "0"
links, err := stack.DoNetlinkRouteRequest(syscall.RTM_GETLINK)
if err != nil {
return nil, fmt.Errorf("RTM_GETLINK failed: %v", err)
}
addrs, err := stack.DoNetlinkRouteRequest(syscall.RTM_GETADDR)
if err != nil {
return nil, fmt.Errorf("RTM_GETADDR failed: %v", err)
}
e = hostinet.ExtractHostInterfaces(links, addrs, stack.interfaces, stack.interfaceAddrs)
if e != nil {
return nil, e
}
return stack, 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 {
// To keep all the supported stacks consistent we don't allow changing this
// value even though it would be possible via an RPC.
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 {
// To keep all the supported stacks consistent we don't allow changing this
// value even though it would be possible via an RPC.
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 {
// To keep all the supported stacks consistent we don't allow changing this
// value even though it would be possible via an RPC.
return syserror.EACCES
}
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