106 lines
3.5 KiB
Go
106 lines
3.5 KiB
Go
// Copyright 2018 Google LLC
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package netlink
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import (
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"fmt"
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"gvisor.googlesource.com/gvisor/pkg/abi/linux"
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"gvisor.googlesource.com/gvisor/pkg/sentry/context"
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"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
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"gvisor.googlesource.com/gvisor/pkg/sentry/kernel"
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"gvisor.googlesource.com/gvisor/pkg/sentry/socket"
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"gvisor.googlesource.com/gvisor/pkg/sentry/socket/unix/transport"
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"gvisor.googlesource.com/gvisor/pkg/syserr"
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)
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// Protocol is the implementation of a netlink socket protocol.
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type Protocol interface {
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// Protocol returns the Linux netlink protocol value.
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Protocol() int
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// ProcessMessage processes a single message from userspace.
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//
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// If err == nil, any messages added to ms will be sent back to the
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// other end of the socket. Setting ms.Multi will cause an NLMSG_DONE
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// message to be sent even if ms contains no messages.
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ProcessMessage(ctx context.Context, hdr linux.NetlinkMessageHeader, data []byte, ms *MessageSet) *syserr.Error
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}
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// Provider is a function that creates a new Protocol for a specific netlink
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// protocol.
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//
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// Note that this is distinct from socket.Provider, which is used for all
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// socket families.
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type Provider func(t *kernel.Task) (Protocol, *syserr.Error)
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// protocols holds a map of all known address protocols and their provider.
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var protocols = make(map[int]Provider)
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// RegisterProvider registers the provider of a given address protocol so that
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// netlink sockets of that type can be created via socket(2).
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//
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// Preconditions: May only be called before any netlink sockets are created.
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func RegisterProvider(protocol int, provider Provider) {
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if p, ok := protocols[protocol]; ok {
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panic(fmt.Sprintf("Netlink protocol %d already provided by %+v", protocol, p))
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}
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protocols[protocol] = provider
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}
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// socketProvider implements socket.Provider.
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type socketProvider struct {
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}
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// Socket implements socket.Provider.Socket.
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func (*socketProvider) Socket(t *kernel.Task, stype transport.SockType, protocol int) (*fs.File, *syserr.Error) {
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// Netlink sockets must be specified as datagram or raw, but they
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// behave the same regardless of type.
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if stype != transport.SockDgram && stype != transport.SockRaw {
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return nil, syserr.ErrSocketNotSupported
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}
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provider, ok := protocols[protocol]
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if !ok {
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return nil, syserr.ErrProtocolNotSupported
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}
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p, err := provider(t)
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if err != nil {
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return nil, err
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}
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s, err := NewSocket(t, p)
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if err != nil {
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return nil, err
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}
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d := socket.NewDirent(t, netlinkSocketDevice)
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defer d.DecRef()
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return fs.NewFile(t, d, fs.FileFlags{Read: true, Write: true}, s), nil
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}
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// Pair implements socket.Provider.Pair by returning an error.
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func (*socketProvider) Pair(*kernel.Task, transport.SockType, int) (*fs.File, *fs.File, *syserr.Error) {
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// Netlink sockets never supports creating socket pairs.
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return nil, nil, syserr.ErrNotSupported
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}
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// init registers the socket provider.
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func init() {
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socket.RegisterProvider(linux.AF_NETLINK, &socketProvider{})
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}
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