Check in gVisor.

PiperOrigin-RevId: 194583126
Change-Id: Ica1d8821a90f74e7e745962d71801c598c652463

1 files changed, 104 insertions, 0 deletions

diff --git a/pkg/sentry/socket/netlink/provider.go b/pkg/sentry/socket/netlink/provider.go
new file mode 100644
index 000000000..36800da4d
--- /dev/null
+++ b/pkg/sentry/socket/netlink/provider.go
@@ -0,0 +1,104 @@
+// 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 netlink
+
+import (
+	"fmt"
+
+	"gvisor.googlesource.com/gvisor/pkg/abi/linux"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/context"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/kernel"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/socket"
+	"gvisor.googlesource.com/gvisor/pkg/syserr"
+	"gvisor.googlesource.com/gvisor/pkg/tcpip/transport/unix"
+)
+
+// Protocol is the implementation of a netlink socket protocol.
+type Protocol interface {
+	// Protocol returns the Linux netlink protocol value.
+	Protocol() int
+
+	// ProcessMessage processes a single message from userspace.
+	//
+	// If err == nil, any messages added to ms will be sent back to the
+	// other end of the socket. Setting ms.Multi will cause an NLMSG_DONE
+	// message to be sent even if ms contains no messages.
+	ProcessMessage(ctx context.Context, hdr linux.NetlinkMessageHeader, data []byte, ms *MessageSet) *syserr.Error
+}
+
+// Provider is a function that creates a new Protocol for a specific netlink
+// protocol.
+//
+// Note that this is distinct from socket.Provider, which is used for all
+// socket families.
+type Provider func(t *kernel.Task) (Protocol, *syserr.Error)
+
+// protocols holds a map of all known address protocols and their provider.
+var protocols = make(map[int]Provider)
+
+// RegisterProvider registers the provider of a given address protocol so that
+// netlink sockets of that type can be created via socket(2).
+//
+// Preconditions: May only be called before any netlink sockets are created.
+func RegisterProvider(protocol int, provider Provider) {
+	if p, ok := protocols[protocol]; ok {
+		panic(fmt.Sprintf("Netlink protocol %d already provided by %+v", protocol, p))
+	}
+
+	protocols[protocol] = provider
+}
+
+// socketProvider implements socket.Provider.
+type socketProvider struct {
+}
+
+// Socket implements socket.Provider.Socket.
+func (*socketProvider) Socket(t *kernel.Task, stype unix.SockType, protocol int) (*fs.File, *syserr.Error) {
+	// Netlink sockets must be specified as datagram or raw, but they
+	// behave the same regardless of type.
+	if stype != unix.SockDgram && stype != unix.SockRaw {
+		return nil, syserr.ErrSocketNotSupported
+	}
+
+	provider, ok := protocols[protocol]
+	if !ok {
+		return nil, syserr.ErrProtocolNotSupported
+	}
+
+	p, err := provider(t)
+	if err != nil {
+		return nil, err
+	}
+
+	s, err := NewSocket(t, p)
+	if err != nil {
+		return nil, err
+	}
+
+	d := socket.NewDirent(t, netlinkSocketDevice)
+	return fs.NewFile(t, d, fs.FileFlags{Read: true, Write: true}, s), nil
+}
+
+// Pair implements socket.Provider.Pair by returning an error.
+func (*socketProvider) Pair(*kernel.Task, unix.SockType, int) (*fs.File, *fs.File, *syserr.Error) {
+	// Netlink sockets never supports creating socket pairs.
+	return nil, nil, syserr.ErrNotSupported
+}
+
+// init registers the socket provider.
+func init() {
+	socket.RegisterProvider(linux.AF_NETLINK, &socketProvider{})
+}