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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 netstack
import (
"syscall"
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/sentry/context"
"gvisor.dev/gvisor/pkg/sentry/fs"
"gvisor.dev/gvisor/pkg/sentry/kernel"
"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
"gvisor.dev/gvisor/pkg/sentry/socket"
"gvisor.dev/gvisor/pkg/syserr"
"gvisor.dev/gvisor/pkg/tcpip"
"gvisor.dev/gvisor/pkg/tcpip/header"
"gvisor.dev/gvisor/pkg/tcpip/network/ipv4"
"gvisor.dev/gvisor/pkg/tcpip/network/ipv6"
"gvisor.dev/gvisor/pkg/tcpip/transport/tcp"
"gvisor.dev/gvisor/pkg/tcpip/transport/udp"
"gvisor.dev/gvisor/pkg/waiter"
)
// provider is an inet socket provider.
type provider struct {
family int
netProto tcpip.NetworkProtocolNumber
}
// getTransportProtocol figures out transport protocol. Currently only TCP,
// UDP, and ICMP are supported. The bool return value is true when this socket
// is associated with a transport protocol. This is only false for SOCK_RAW,
// IPPROTO_IP sockets.
func getTransportProtocol(ctx context.Context, stype linux.SockType, protocol int) (tcpip.TransportProtocolNumber, bool, *syserr.Error) {
switch stype {
case linux.SOCK_STREAM:
if protocol != 0 && protocol != syscall.IPPROTO_TCP {
return 0, true, syserr.ErrInvalidArgument
}
return tcp.ProtocolNumber, true, nil
case linux.SOCK_DGRAM:
switch protocol {
case 0, syscall.IPPROTO_UDP:
return udp.ProtocolNumber, true, nil
case syscall.IPPROTO_ICMP:
return header.ICMPv4ProtocolNumber, true, nil
case syscall.IPPROTO_ICMPV6:
return header.ICMPv6ProtocolNumber, true, nil
}
case linux.SOCK_RAW:
// TODO(b/142504697): "In order to create a raw socket, a
// process must have the CAP_NET_RAW capability in the user
// namespace that governs its network namespace." - raw(7)
// Raw sockets require CAP_NET_RAW.
creds := auth.CredentialsFromContext(ctx)
if !creds.HasCapability(linux.CAP_NET_RAW) {
return 0, true, syserr.ErrNotPermitted
}
switch protocol {
case syscall.IPPROTO_ICMP:
return header.ICMPv4ProtocolNumber, true, nil
case syscall.IPPROTO_UDP:
return header.UDPProtocolNumber, true, nil
case syscall.IPPROTO_TCP:
return header.TCPProtocolNumber, true, nil
// IPPROTO_RAW signifies that the raw socket isn't assigned to
// a transport protocol. Users will be able to write packets'
// IP headers and won't receive anything.
case syscall.IPPROTO_RAW:
return tcpip.TransportProtocolNumber(0), false, nil
}
}
return 0, true, syserr.ErrProtocolNotSupported
}
// Socket creates a new socket object for the AF_INET, AF_INET6, or AF_PACKET
// family.
func (p *provider) Socket(t *kernel.Task, stype linux.SockType, protocol int) (*fs.File, *syserr.Error) {
// Fail right away if we don't have a stack.
stack := t.NetworkContext()
if stack == nil {
// Don't propagate an error here. Instead, allow the socket
// code to continue searching for another provider.
return nil, nil
}
eps, ok := stack.(*Stack)
if !ok {
return nil, nil
}
// Packet sockets are handled separately, since they are neither INET
// nor INET6 specific.
if p.family == linux.AF_PACKET {
return packetSocket(t, eps, stype, protocol)
}
// Figure out the transport protocol.
transProto, associated, err := getTransportProtocol(t, stype, protocol)
if err != nil {
return nil, err
}
// Create the endpoint.
var ep tcpip.Endpoint
var e *tcpip.Error
wq := &waiter.Queue{}
if stype == linux.SOCK_RAW {
ep, e = eps.Stack.NewRawEndpoint(transProto, p.netProto, wq, associated)
} else {
ep, e = eps.Stack.NewEndpoint(transProto, p.netProto, wq)
}
if e != nil {
return nil, syserr.TranslateNetstackError(e)
}
return New(t, p.family, stype, int(transProto), wq, ep)
}
func packetSocket(t *kernel.Task, epStack *Stack, stype linux.SockType, protocol int) (*fs.File, *syserr.Error) {
// TODO(b/142504697): "In order to create a packet socket, a process
// must have the CAP_NET_RAW capability in the user namespace that
// governs its network namespace." - packet(7)
// Packet sockets require CAP_NET_RAW.
creds := auth.CredentialsFromContext(t)
if !creds.HasCapability(linux.CAP_NET_RAW) {
return nil, syserr.ErrNotPermitted
}
// "cooked" packets don't contain link layer information.
var cooked bool
switch stype {
case linux.SOCK_DGRAM:
cooked = true
case linux.SOCK_RAW:
cooked = false
default:
return nil, syserr.ErrProtocolNotSupported
}
// protocol is passed in network byte order, but netstack wants it in
// host order.
netProto := tcpip.NetworkProtocolNumber(ntohs(uint16(protocol)))
wq := &waiter.Queue{}
ep, err := epStack.Stack.NewPacketEndpoint(cooked, netProto, wq)
if err != nil {
return nil, syserr.TranslateNetstackError(err)
}
return New(t, linux.AF_PACKET, stype, protocol, wq, ep)
}
// Pair just returns nil sockets (not supported).
func (*provider) Pair(*kernel.Task, linux.SockType, int) (*fs.File, *fs.File, *syserr.Error) {
return nil, nil, nil
}
// init registers socket providers for AF_INET, AF_INET6, and AF_PACKET.
func init() {
// Providers backed by netstack.
p := []provider{
{
family: linux.AF_INET,
netProto: ipv4.ProtocolNumber,
},
{
family: linux.AF_INET6,
netProto: ipv6.ProtocolNumber,
},
{
family: linux.AF_PACKET,
},
}
for i := range p {
socket.RegisterProvider(p[i].family, &p[i])
}
}
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