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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 socket provides the interfaces that need to be provided by socket
// implementations and providers, as well as per family demultiplexing of socket
// creation.
package socket
import (
"fmt"
"sync/atomic"
"gvisor.googlesource.com/gvisor/pkg/abi/linux"
"gvisor.googlesource.com/gvisor/pkg/sentry/context"
"gvisor.googlesource.com/gvisor/pkg/sentry/device"
"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
"gvisor.googlesource.com/gvisor/pkg/sentry/fs/fsutil"
"gvisor.googlesource.com/gvisor/pkg/sentry/kernel"
"gvisor.googlesource.com/gvisor/pkg/sentry/kernel/kdefs"
ktime "gvisor.googlesource.com/gvisor/pkg/sentry/kernel/time"
"gvisor.googlesource.com/gvisor/pkg/sentry/usermem"
"gvisor.googlesource.com/gvisor/pkg/syserr"
"gvisor.googlesource.com/gvisor/pkg/tcpip"
"gvisor.googlesource.com/gvisor/pkg/tcpip/transport/unix"
)
// ControlMessages represents the union of unix control messages and tcpip
// control messages.
type ControlMessages struct {
Unix unix.ControlMessages
IP tcpip.ControlMessages
}
// Socket is the interface containing socket syscalls used by the syscall layer
// to redirect them to the appropriate implementation.
type Socket interface {
fs.FileOperations
// Connect implements the connect(2) linux syscall.
Connect(t *kernel.Task, sockaddr []byte, blocking bool) *syserr.Error
// Accept implements the accept4(2) linux syscall.
// Returns fd, real peer address length and error. Real peer address
// length is only set if len(peer) > 0.
Accept(t *kernel.Task, peerRequested bool, flags int, blocking bool) (kdefs.FD, interface{}, uint32, *syserr.Error)
// Bind implements the bind(2) linux syscall.
Bind(t *kernel.Task, sockaddr []byte) *syserr.Error
// Listen implements the listen(2) linux syscall.
Listen(t *kernel.Task, backlog int) *syserr.Error
// Shutdown implements the shutdown(2) linux syscall.
Shutdown(t *kernel.Task, how int) *syserr.Error
// GetSockOpt implements the getsockopt(2) linux syscall.
GetSockOpt(t *kernel.Task, level int, name int, outLen int) (interface{}, *syserr.Error)
// SetSockOpt implements the setsockopt(2) linux syscall.
SetSockOpt(t *kernel.Task, level int, name int, opt []byte) *syserr.Error
// GetSockName implements the getsockname(2) linux syscall.
//
// addrLen is the address length to be returned to the application, not
// necessarily the actual length of the address.
GetSockName(t *kernel.Task) (addr interface{}, addrLen uint32, err *syserr.Error)
// GetPeerName implements the getpeername(2) linux syscall.
//
// addrLen is the address length to be returned to the application, not
// necessarily the actual length of the address.
GetPeerName(t *kernel.Task) (addr interface{}, addrLen uint32, err *syserr.Error)
// RecvMsg implements the recvmsg(2) linux syscall.
//
// senderAddrLen is the address length to be returned to the application,
// not necessarily the actual length of the address.
RecvMsg(t *kernel.Task, dst usermem.IOSequence, flags int, haveDeadline bool, deadline ktime.Time, senderRequested bool, controlDataLen uint64) (n int, senderAddr interface{}, senderAddrLen uint32, controlMessages ControlMessages, err *syserr.Error)
// SendMsg implements the sendmsg(2) linux syscall. SendMsg does not take
// ownership of the ControlMessage on error.
SendMsg(t *kernel.Task, src usermem.IOSequence, to []byte, flags int, controlMessages ControlMessages) (n int, err *syserr.Error)
// SetRecvTimeout sets the timeout (in ns) for recv operations. Zero means
// no timeout.
SetRecvTimeout(nanoseconds int64)
// RecvTimeout gets the current timeout (in ns) for recv operations. Zero
// means no timeout.
RecvTimeout() int64
}
// Provider is the interface implemented by providers of sockets for specific
// address families (e.g., AF_INET).
type Provider interface {
// Socket creates a new socket.
//
// If a nil Socket _and_ a nil error is returned, it means that the
// protocol is not supported. A non-nil error should only be returned
// if the protocol is supported, but an error occurs during creation.
Socket(t *kernel.Task, stype unix.SockType, protocol int) (*fs.File, *syserr.Error)
// Pair creates a pair of connected sockets.
//
// See Socket for error information.
Pair(t *kernel.Task, stype unix.SockType, protocol int) (*fs.File, *fs.File, *syserr.Error)
}
// families holds a map of all known address families and their providers.
var families = make(map[int][]Provider)
// RegisterProvider registers the provider of a given address family so that
// sockets of that type can be created via socket() and/or socketpair()
// syscalls.
func RegisterProvider(family int, provider Provider) {
families[family] = append(families[family], provider)
}
// New creates a new socket with the given family, type and protocol.
func New(t *kernel.Task, family int, stype unix.SockType, protocol int) (*fs.File, *syserr.Error) {
for _, p := range families[family] {
s, err := p.Socket(t, stype, protocol)
if err != nil {
return nil, err
}
if s != nil {
return s, nil
}
}
return nil, syserr.ErrAddressFamilyNotSupported
}
// Pair creates a new connected socket pair with the given family, type and
// protocol.
func Pair(t *kernel.Task, family int, stype unix.SockType, protocol int) (*fs.File, *fs.File, *syserr.Error) {
providers, ok := families[family]
if !ok {
return nil, nil, syserr.ErrAddressFamilyNotSupported
}
for _, p := range providers {
s, t, err := p.Pair(t, stype, protocol)
if err != nil {
return nil, nil, err
}
if s != nil && t != nil {
return s, t, nil
}
}
return nil, nil, syserr.ErrSocketNotSupported
}
// NewDirent returns a sockfs fs.Dirent that resides on device d.
func NewDirent(ctx context.Context, d *device.Device) *fs.Dirent {
ino := d.NextIno()
// There is no real filesystem backing this pipe, so we pass in a nil
// Filesystem.
inode := fs.NewInode(fsutil.NewSimpleInodeOperations(fsutil.InodeSimpleAttributes{
FSType: linux.SOCKFS_MAGIC,
UAttr: fs.WithCurrentTime(ctx, fs.UnstableAttr{
Owner: fs.FileOwnerFromContext(ctx),
Perms: fs.FilePermissions{
User: fs.PermMask{Read: true, Write: true},
},
Links: 1,
}),
}), fs.NewNonCachingMountSource(nil, fs.MountSourceFlags{}), fs.StableAttr{
Type: fs.Socket,
DeviceID: d.DeviceID(),
InodeID: ino,
BlockSize: usermem.PageSize,
})
// Dirent name matches net/socket.c:sockfs_dname.
return fs.NewDirent(inode, fmt.Sprintf("socket:[%d]", ino))
}
// ReceiveTimeout stores a timeout for receive calls.
//
// It is meant to be embedded into Socket implementations to help satisfy the
// interface.
//
// Care must be taken when copying ReceiveTimeout as it contains atomic
// variables.
//
// +stateify savable
type ReceiveTimeout struct {
// ns is length of the timeout in nanoseconds.
//
// ns must be accessed atomically.
ns int64
}
// SetRecvTimeout implements Socket.SetRecvTimeout.
func (rt *ReceiveTimeout) SetRecvTimeout(nanoseconds int64) {
atomic.StoreInt64(&rt.ns, nanoseconds)
}
// RecvTimeout implements Socket.RecvTimeout.
func (rt *ReceiveTimeout) RecvTimeout() int64 {
return atomic.LoadInt64(&rt.ns)
}
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