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// Copyright 2020 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 gofer
import (
"syscall"
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/context"
"gvisor.dev/gvisor/pkg/log"
"gvisor.dev/gvisor/pkg/p9"
"gvisor.dev/gvisor/pkg/sentry/fsimpl/host"
"gvisor.dev/gvisor/pkg/sentry/socket/unix/transport"
"gvisor.dev/gvisor/pkg/syserr"
"gvisor.dev/gvisor/pkg/waiter"
)
func (d *dentry) isSocket() bool {
return d.fileType() == linux.S_IFSOCK
}
// endpoint is a Gofer-backed transport.BoundEndpoint.
//
// An endpoint's lifetime is the time between when filesystem.BoundEndpointAt()
// is called and either BoundEndpoint.BidirectionalConnect or
// BoundEndpoint.UnidirectionalConnect is called.
type endpoint struct {
// dentry is the filesystem dentry which produced this endpoint.
dentry *dentry
// file is the p9 file that contains a single unopened fid.
file p9.File
// path is the sentry path where this endpoint is bound.
path string
}
func sockTypeToP9(t linux.SockType) (p9.ConnectFlags, bool) {
switch t {
case linux.SOCK_STREAM:
return p9.StreamSocket, true
case linux.SOCK_SEQPACKET:
return p9.SeqpacketSocket, true
case linux.SOCK_DGRAM:
return p9.DgramSocket, true
}
return 0, false
}
// BidirectionalConnect implements ConnectableEndpoint.BidirectionalConnect.
func (e *endpoint) BidirectionalConnect(ctx context.Context, ce transport.ConnectingEndpoint, returnConnect func(transport.Receiver, transport.ConnectedEndpoint)) *syserr.Error {
cf, ok := sockTypeToP9(ce.Type())
if !ok {
return syserr.ErrConnectionRefused
}
// No lock ordering required as only the ConnectingEndpoint has a mutex.
ce.Lock()
// Check connecting state.
if ce.Connected() {
ce.Unlock()
return syserr.ErrAlreadyConnected
}
if ce.Listening() {
ce.Unlock()
return syserr.ErrInvalidEndpointState
}
c, err := e.newConnectedEndpoint(ctx, cf, ce.WaiterQueue())
if err != nil {
ce.Unlock()
return err
}
returnConnect(c, c)
ce.Unlock()
c.Init()
return nil
}
// UnidirectionalConnect implements
// transport.BoundEndpoint.UnidirectionalConnect.
func (e *endpoint) UnidirectionalConnect(ctx context.Context) (transport.ConnectedEndpoint, *syserr.Error) {
c, err := e.newConnectedEndpoint(ctx, p9.DgramSocket, &waiter.Queue{})
if err != nil {
return nil, err
}
c.Init()
// We don't need the receiver.
c.CloseRecv()
c.Release()
return c, nil
}
func (e *endpoint) newConnectedEndpoint(ctx context.Context, flags p9.ConnectFlags, queue *waiter.Queue) (*host.SCMConnectedEndpoint, *syserr.Error) {
hostFile, err := e.file.Connect(flags)
if err != nil {
return nil, syserr.ErrConnectionRefused
}
// Dup the fd so that the new endpoint can manage its lifetime.
hostFD, err := syscall.Dup(hostFile.FD())
if err != nil {
log.Warningf("Could not dup host socket fd %d: %v", hostFile.FD(), err)
return nil, syserr.FromError(err)
}
// After duplicating, we no longer need hostFile.
hostFile.Close()
c, serr := host.NewSCMEndpoint(ctx, hostFD, queue, e.path)
if serr != nil {
log.Warningf("Gofer returned invalid host socket for BidirectionalConnect; file %+v flags %+v: %v", e.file, flags, serr)
return nil, serr
}
return c, nil
}
// Release implements transport.BoundEndpoint.Release.
func (e *endpoint) Release() {
e.dentry.DecRef()
}
// Passcred implements transport.BoundEndpoint.Passcred.
func (e *endpoint) Passcred() bool {
return false
}
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