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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 netlink
import (
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/context"
"gvisor.dev/gvisor/pkg/sentry/arch"
fslock "gvisor.dev/gvisor/pkg/sentry/fs/lock"
"gvisor.dev/gvisor/pkg/sentry/kernel"
"gvisor.dev/gvisor/pkg/sentry/socket"
"gvisor.dev/gvisor/pkg/sentry/socket/unix"
"gvisor.dev/gvisor/pkg/sentry/socket/unix/transport"
"gvisor.dev/gvisor/pkg/sentry/vfs"
"gvisor.dev/gvisor/pkg/syserr"
"gvisor.dev/gvisor/pkg/syserror"
"gvisor.dev/gvisor/pkg/tcpip"
"gvisor.dev/gvisor/pkg/usermem"
"gvisor.dev/gvisor/pkg/waiter"
)
// SocketVFS2 is the base VFS2 socket type for netlink sockets.
//
// This implementation only supports userspace sending and receiving messages
// to/from the kernel.
//
// SocketVFS2 implements socket.SocketVFS2 and transport.Credentialer.
type SocketVFS2 struct {
vfsfd vfs.FileDescription
vfs.FileDescriptionDefaultImpl
vfs.DentryMetadataFileDescriptionImpl
vfs.LockFD
socketOpsCommon
}
var _ socket.SocketVFS2 = (*SocketVFS2)(nil)
var _ transport.Credentialer = (*SocketVFS2)(nil)
// NewVFS2 creates a new SocketVFS2.
func NewVFS2(t *kernel.Task, skType linux.SockType, protocol Protocol) (*SocketVFS2, *syserr.Error) {
// Datagram endpoint used to buffer kernel -> user messages.
ep := transport.NewConnectionless(t)
// Bind the endpoint for good measure so we can connect to it. The
// bound address will never be exposed.
if err := ep.Bind(tcpip.FullAddress{Addr: "dummy"}, nil); err != nil {
ep.Close(t)
return nil, err
}
// Create a connection from which the kernel can write messages.
connection, err := ep.(transport.BoundEndpoint).UnidirectionalConnect(t)
if err != nil {
ep.Close(t)
return nil, err
}
fd := &SocketVFS2{
socketOpsCommon: socketOpsCommon{
ports: t.Kernel().NetlinkPorts(),
protocol: protocol,
skType: skType,
ep: ep,
connection: connection,
sendBufferSize: defaultSendBufferSize,
},
}
fd.LockFD.Init(&vfs.FileLocks{})
return fd, nil
}
// Readiness implements waiter.Waitable.Readiness.
func (s *SocketVFS2) Readiness(mask waiter.EventMask) waiter.EventMask {
return s.socketOpsCommon.Readiness(mask)
}
// EventRegister implements waiter.Waitable.EventRegister.
func (s *SocketVFS2) EventRegister(e *waiter.Entry, mask waiter.EventMask) {
s.socketOpsCommon.EventRegister(e, mask)
}
// EventUnregister implements waiter.Waitable.EventUnregister.
func (s *SocketVFS2) EventUnregister(e *waiter.Entry) {
s.socketOpsCommon.EventUnregister(e)
}
// Ioctl implements vfs.FileDescriptionImpl.
func (*SocketVFS2) Ioctl(context.Context, usermem.IO, arch.SyscallArguments) (uintptr, error) {
// TODO(b/68878065): no ioctls supported.
return 0, syserror.ENOTTY
}
// PRead implements vfs.FileDescriptionImpl.
func (s *SocketVFS2) PRead(ctx context.Context, dst usermem.IOSequence, offset int64, opts vfs.ReadOptions) (int64, error) {
return 0, syserror.ESPIPE
}
// Read implements vfs.FileDescriptionImpl.
func (s *SocketVFS2) Read(ctx context.Context, dst usermem.IOSequence, opts vfs.ReadOptions) (int64, error) {
// All flags other than RWF_NOWAIT should be ignored.
// TODO(gvisor.dev/issue/2601): Support RWF_NOWAIT.
if opts.Flags != 0 {
return 0, syserror.EOPNOTSUPP
}
if dst.NumBytes() == 0 {
return 0, nil
}
return dst.CopyOutFrom(ctx, &unix.EndpointReader{
Endpoint: s.ep,
})
}
// PWrite implements vfs.FileDescriptionImpl.
func (s *SocketVFS2) PWrite(ctx context.Context, src usermem.IOSequence, offset int64, opts vfs.WriteOptions) (int64, error) {
return 0, syserror.ESPIPE
}
// Write implements vfs.FileDescriptionImpl.
func (s *SocketVFS2) Write(ctx context.Context, src usermem.IOSequence, opts vfs.WriteOptions) (int64, error) {
// All flags other than RWF_NOWAIT should be ignored.
// TODO(gvisor.dev/issue/2601): Support RWF_NOWAIT.
if opts.Flags != 0 {
return 0, syserror.EOPNOTSUPP
}
n, err := s.sendMsg(ctx, src, nil, 0, socket.ControlMessages{})
return int64(n), err.ToError()
}
// LockPOSIX implements vfs.FileDescriptionImpl.LockPOSIX.
func (s *SocketVFS2) LockPOSIX(ctx context.Context, uid fslock.UniqueID, t fslock.LockType, start, length uint64, whence int16, block fslock.Blocker) error {
return s.Locks().LockPOSIX(ctx, &s.vfsfd, uid, t, start, length, whence, block)
}
// UnlockPOSIX implements vfs.FileDescriptionImpl.UnlockPOSIX.
func (s *SocketVFS2) UnlockPOSIX(ctx context.Context, uid fslock.UniqueID, start, length uint64, whence int16) error {
return s.Locks().UnlockPOSIX(ctx, &s.vfsfd, uid, start, length, whence)
}
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