From b8f56c79be40d9c75f4e2f279c9d821d1c1c3569 Mon Sep 17 00:00:00 2001 From: Ting-Yu Wang Date: Fri, 21 Feb 2020 15:41:56 -0800 Subject: Implement tap/tun device in vfs. PiperOrigin-RevId: 296526279 --- pkg/abi/linux/BUILD | 1 + pkg/abi/linux/ioctl.go | 26 ++ pkg/abi/linux/ioctl_tun.go | 29 ++ pkg/sentry/fs/dev/BUILD | 5 + pkg/sentry/fs/dev/dev.go | 10 +- pkg/sentry/fs/dev/net_tun.go | 170 +++++++++++ pkg/syserror/syserror.go | 1 + pkg/tcpip/buffer/view.go | 6 + pkg/tcpip/link/channel/BUILD | 1 + pkg/tcpip/link/channel/channel.go | 180 +++++++++--- pkg/tcpip/link/tun/BUILD | 18 +- pkg/tcpip/link/tun/device.go | 352 +++++++++++++++++++++++ pkg/tcpip/link/tun/protocol.go | 56 ++++ pkg/tcpip/stack/nic.go | 32 +++ pkg/tcpip/stack/stack.go | 39 +++ test/syscalls/BUILD | 2 + test/syscalls/linux/BUILD | 30 ++ test/syscalls/linux/dev.cc | 7 + test/syscalls/linux/socket_netlink_route_util.cc | 163 +++++++++++ test/syscalls/linux/socket_netlink_route_util.h | 55 ++++ test/syscalls/linux/tuntap.cc | 346 ++++++++++++++++++++++ 21 files changed, 1490 insertions(+), 39 deletions(-) create mode 100644 pkg/abi/linux/ioctl_tun.go create mode 100644 pkg/sentry/fs/dev/net_tun.go create mode 100644 pkg/tcpip/link/tun/device.go create mode 100644 pkg/tcpip/link/tun/protocol.go create mode 100644 test/syscalls/linux/socket_netlink_route_util.cc create mode 100644 test/syscalls/linux/socket_netlink_route_util.h create mode 100644 test/syscalls/linux/tuntap.cc diff --git a/pkg/abi/linux/BUILD b/pkg/abi/linux/BUILD index a89f34d4b..322d1ccc4 100644 --- a/pkg/abi/linux/BUILD +++ b/pkg/abi/linux/BUILD @@ -30,6 +30,7 @@ go_library( "futex.go", "inotify.go", "ioctl.go", + "ioctl_tun.go", "ip.go", "ipc.go", "limits.go", diff --git a/pkg/abi/linux/ioctl.go b/pkg/abi/linux/ioctl.go index 0e18db9ef..2062e6a4b 100644 --- a/pkg/abi/linux/ioctl.go +++ b/pkg/abi/linux/ioctl.go @@ -72,3 +72,29 @@ const ( SIOCGMIIPHY = 0x8947 SIOCGMIIREG = 0x8948 ) + +// ioctl(2) directions. Used to calculate requests number. +// Constants from asm-generic/ioctl.h. +const ( + _IOC_NONE = 0 + _IOC_WRITE = 1 + _IOC_READ = 2 +) + +// Constants from asm-generic/ioctl.h. +const ( + _IOC_NRBITS = 8 + _IOC_TYPEBITS = 8 + _IOC_SIZEBITS = 14 + _IOC_DIRBITS = 2 + + _IOC_NRSHIFT = 0 + _IOC_TYPESHIFT = _IOC_NRSHIFT + _IOC_NRBITS + _IOC_SIZESHIFT = _IOC_TYPESHIFT + _IOC_TYPEBITS + _IOC_DIRSHIFT = _IOC_SIZESHIFT + _IOC_SIZEBITS +) + +// IOC outputs the result of _IOC macro in asm-generic/ioctl.h. +func IOC(dir, typ, nr, size uint32) uint32 { + return uint32(dir)<<_IOC_DIRSHIFT | typ<<_IOC_TYPESHIFT | nr<<_IOC_NRSHIFT | size<<_IOC_SIZESHIFT +} diff --git a/pkg/abi/linux/ioctl_tun.go b/pkg/abi/linux/ioctl_tun.go new file mode 100644 index 000000000..c59c9c136 --- /dev/null +++ b/pkg/abi/linux/ioctl_tun.go @@ -0,0 +1,29 @@ +// 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 linux + +// ioctl(2) request numbers from linux/if_tun.h +var ( + TUNSETIFF = IOC(_IOC_WRITE, 'T', 202, 4) + TUNGETIFF = IOC(_IOC_READ, 'T', 210, 4) +) + +// Flags from net/if_tun.h +const ( + IFF_TUN = 0x0001 + IFF_TAP = 0x0002 + IFF_NO_PI = 0x1000 + IFF_NOFILTER = 0x1000 +) diff --git a/pkg/sentry/fs/dev/BUILD b/pkg/sentry/fs/dev/BUILD index 4c4b7d5cc..9b6bb26d0 100644 --- a/pkg/sentry/fs/dev/BUILD +++ b/pkg/sentry/fs/dev/BUILD @@ -9,6 +9,7 @@ go_library( "device.go", "fs.go", "full.go", + "net_tun.go", "null.go", "random.go", "tty.go", @@ -19,15 +20,19 @@ go_library( "//pkg/context", "//pkg/rand", "//pkg/safemem", + "//pkg/sentry/arch", "//pkg/sentry/device", "//pkg/sentry/fs", "//pkg/sentry/fs/fsutil", "//pkg/sentry/fs/ramfs", "//pkg/sentry/fs/tmpfs", + "//pkg/sentry/kernel", "//pkg/sentry/memmap", "//pkg/sentry/mm", "//pkg/sentry/pgalloc", + "//pkg/sentry/socket/netstack", "//pkg/syserror", + "//pkg/tcpip/link/tun", "//pkg/usermem", "//pkg/waiter", ], diff --git a/pkg/sentry/fs/dev/dev.go b/pkg/sentry/fs/dev/dev.go index 35bd23991..7e66c29b0 100644 --- a/pkg/sentry/fs/dev/dev.go +++ b/pkg/sentry/fs/dev/dev.go @@ -66,8 +66,8 @@ func newMemDevice(ctx context.Context, iops fs.InodeOperations, msrc *fs.MountSo }) } -func newDirectory(ctx context.Context, msrc *fs.MountSource) *fs.Inode { - iops := ramfs.NewDir(ctx, nil, fs.RootOwner, fs.FilePermsFromMode(0555)) +func newDirectory(ctx context.Context, contents map[string]*fs.Inode, msrc *fs.MountSource) *fs.Inode { + iops := ramfs.NewDir(ctx, contents, fs.RootOwner, fs.FilePermsFromMode(0555)) return fs.NewInode(ctx, iops, msrc, fs.StableAttr{ DeviceID: devDevice.DeviceID(), InodeID: devDevice.NextIno(), @@ -111,7 +111,7 @@ func New(ctx context.Context, msrc *fs.MountSource) *fs.Inode { // A devpts is typically mounted at /dev/pts to provide // pseudoterminal support. Place an empty directory there for // the devpts to be mounted over. - "pts": newDirectory(ctx, msrc), + "pts": newDirectory(ctx, nil, msrc), // Similarly, applications expect a ptmx device at /dev/ptmx // connected to the terminals provided by /dev/pts/. Rather // than creating a device directly (which requires a hairy @@ -124,6 +124,10 @@ func New(ctx context.Context, msrc *fs.MountSource) *fs.Inode { "ptmx": newSymlink(ctx, "pts/ptmx", msrc), "tty": newCharacterDevice(ctx, newTTYDevice(ctx, fs.RootOwner, 0666), msrc, ttyDevMajor, ttyDevMinor), + + "net": newDirectory(ctx, map[string]*fs.Inode{ + "tun": newCharacterDevice(ctx, newNetTunDevice(ctx, fs.RootOwner, 0666), msrc, netTunDevMajor, netTunDevMinor), + }, msrc), } iops := ramfs.NewDir(ctx, contents, fs.RootOwner, fs.FilePermsFromMode(0555)) diff --git a/pkg/sentry/fs/dev/net_tun.go b/pkg/sentry/fs/dev/net_tun.go new file mode 100644 index 000000000..755644488 --- /dev/null +++ b/pkg/sentry/fs/dev/net_tun.go @@ -0,0 +1,170 @@ +// 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 dev + +import ( + "gvisor.dev/gvisor/pkg/abi/linux" + "gvisor.dev/gvisor/pkg/context" + "gvisor.dev/gvisor/pkg/sentry/arch" + "gvisor.dev/gvisor/pkg/sentry/fs" + "gvisor.dev/gvisor/pkg/sentry/fs/fsutil" + "gvisor.dev/gvisor/pkg/sentry/kernel" + "gvisor.dev/gvisor/pkg/sentry/socket/netstack" + "gvisor.dev/gvisor/pkg/syserror" + "gvisor.dev/gvisor/pkg/tcpip/link/tun" + "gvisor.dev/gvisor/pkg/usermem" + "gvisor.dev/gvisor/pkg/waiter" +) + +const ( + netTunDevMajor = 10 + netTunDevMinor = 200 +) + +// +stateify savable +type netTunInodeOperations struct { + fsutil.InodeGenericChecker `state:"nosave"` + fsutil.InodeNoExtendedAttributes `state:"nosave"` + fsutil.InodeNoopAllocate `state:"nosave"` + fsutil.InodeNoopRelease `state:"nosave"` + fsutil.InodeNoopTruncate `state:"nosave"` + fsutil.InodeNoopWriteOut `state:"nosave"` + fsutil.InodeNotDirectory `state:"nosave"` + fsutil.InodeNotMappable `state:"nosave"` + fsutil.InodeNotSocket `state:"nosave"` + fsutil.InodeNotSymlink `state:"nosave"` + fsutil.InodeVirtual `state:"nosave"` + + fsutil.InodeSimpleAttributes +} + +var _ fs.InodeOperations = (*netTunInodeOperations)(nil) + +func newNetTunDevice(ctx context.Context, owner fs.FileOwner, mode linux.FileMode) *netTunInodeOperations { + return &netTunInodeOperations{ + InodeSimpleAttributes: fsutil.NewInodeSimpleAttributes(ctx, owner, fs.FilePermsFromMode(mode), linux.TMPFS_MAGIC), + } +} + +// GetFile implements fs.InodeOperations.GetFile. +func (iops *netTunInodeOperations) GetFile(ctx context.Context, d *fs.Dirent, flags fs.FileFlags) (*fs.File, error) { + return fs.NewFile(ctx, d, flags, &netTunFileOperations{}), nil +} + +// +stateify savable +type netTunFileOperations struct { + fsutil.FileNoSeek `state:"nosave"` + fsutil.FileNoMMap `state:"nosave"` + fsutil.FileNoSplice `state:"nosave"` + fsutil.FileNoopFlush `state:"nosave"` + fsutil.FileNoopFsync `state:"nosave"` + fsutil.FileNotDirReaddir `state:"nosave"` + fsutil.FileUseInodeUnstableAttr `state:"nosave"` + + device tun.Device +} + +var _ fs.FileOperations = (*netTunFileOperations)(nil) + +// Release implements fs.FileOperations.Release. +func (fops *netTunFileOperations) Release() { + fops.device.Release() +} + +// Ioctl implements fs.FileOperations.Ioctl. +func (fops *netTunFileOperations) Ioctl(ctx context.Context, file *fs.File, io usermem.IO, args arch.SyscallArguments) (uintptr, error) { + request := args[1].Uint() + data := args[2].Pointer() + + switch request { + case linux.TUNSETIFF: + t := kernel.TaskFromContext(ctx) + if t == nil { + panic("Ioctl should be called from a task context") + } + if !t.HasCapability(linux.CAP_NET_ADMIN) { + return 0, syserror.EPERM + } + stack, ok := t.NetworkContext().(*netstack.Stack) + if !ok { + return 0, syserror.EINVAL + } + + var req linux.IFReq + if _, err := usermem.CopyObjectIn(ctx, io, data, &req, usermem.IOOpts{ + AddressSpaceActive: true, + }); err != nil { + return 0, err + } + flags := usermem.ByteOrder.Uint16(req.Data[:]) + return 0, fops.device.SetIff(stack.Stack, req.Name(), flags) + + case linux.TUNGETIFF: + var req linux.IFReq + + copy(req.IFName[:], fops.device.Name()) + + // Linux adds IFF_NOFILTER (the same value as IFF_NO_PI unfortunately) when + // there is no sk_filter. See __tun_chr_ioctl() in net/drivers/tun.c. + flags := fops.device.Flags() | linux.IFF_NOFILTER + usermem.ByteOrder.PutUint16(req.Data[:], flags) + + _, err := usermem.CopyObjectOut(ctx, io, data, &req, usermem.IOOpts{ + AddressSpaceActive: true, + }) + return 0, err + + default: + return 0, syserror.ENOTTY + } +} + +// Write implements fs.FileOperations.Write. +func (fops *netTunFileOperations) Write(ctx context.Context, file *fs.File, src usermem.IOSequence, offset int64) (int64, error) { + data := make([]byte, src.NumBytes()) + if _, err := src.CopyIn(ctx, data); err != nil { + return 0, err + } + return fops.device.Write(data) +} + +// Read implements fs.FileOperations.Read. +func (fops *netTunFileOperations) Read(ctx context.Context, file *fs.File, dst usermem.IOSequence, offset int64) (int64, error) { + data, err := fops.device.Read() + if err != nil { + return 0, err + } + n, err := dst.CopyOut(ctx, data) + if n > 0 && n < len(data) { + // Not an error for partial copying. Packet truncated. + err = nil + } + return int64(n), err +} + +// Readiness implements watier.Waitable.Readiness. +func (fops *netTunFileOperations) Readiness(mask waiter.EventMask) waiter.EventMask { + return fops.device.Readiness(mask) +} + +// EventRegister implements watier.Waitable.EventRegister. +func (fops *netTunFileOperations) EventRegister(e *waiter.Entry, mask waiter.EventMask) { + fops.device.EventRegister(e, mask) +} + +// EventUnregister implements watier.Waitable.EventUnregister. +func (fops *netTunFileOperations) EventUnregister(e *waiter.Entry) { + fops.device.EventUnregister(e) +} diff --git a/pkg/syserror/syserror.go b/pkg/syserror/syserror.go index 2269f6237..4b5a0fca6 100644 --- a/pkg/syserror/syserror.go +++ b/pkg/syserror/syserror.go @@ -29,6 +29,7 @@ var ( EACCES = error(syscall.EACCES) EAGAIN = error(syscall.EAGAIN) EBADF = error(syscall.EBADF) + EBADFD = error(syscall.EBADFD) EBUSY = error(syscall.EBUSY) ECHILD = error(syscall.ECHILD) ECONNREFUSED = error(syscall.ECONNREFUSED) diff --git a/pkg/tcpip/buffer/view.go b/pkg/tcpip/buffer/view.go index 150310c11..17e94c562 100644 --- a/pkg/tcpip/buffer/view.go +++ b/pkg/tcpip/buffer/view.go @@ -156,3 +156,9 @@ func (vv *VectorisedView) Append(vv2 VectorisedView) { vv.views = append(vv.views, vv2.views...) vv.size += vv2.size } + +// AppendView appends the given view into this vectorised view. +func (vv *VectorisedView) AppendView(v View) { + vv.views = append(vv.views, v) + vv.size += len(v) +} diff --git a/pkg/tcpip/link/channel/BUILD b/pkg/tcpip/link/channel/BUILD index 3974c464e..b8b93e78e 100644 --- a/pkg/tcpip/link/channel/BUILD +++ b/pkg/tcpip/link/channel/BUILD @@ -7,6 +7,7 @@ go_library( srcs = ["channel.go"], visibility = ["//visibility:public"], deps = [ + "//pkg/sync", "//pkg/tcpip", "//pkg/tcpip/buffer", "//pkg/tcpip/stack", diff --git a/pkg/tcpip/link/channel/channel.go b/pkg/tcpip/link/channel/channel.go index 78d447acd..5944ba190 100644 --- a/pkg/tcpip/link/channel/channel.go +++ b/pkg/tcpip/link/channel/channel.go @@ -20,6 +20,7 @@ package channel import ( "context" + "gvisor.dev/gvisor/pkg/sync" "gvisor.dev/gvisor/pkg/tcpip" "gvisor.dev/gvisor/pkg/tcpip/buffer" "gvisor.dev/gvisor/pkg/tcpip/stack" @@ -33,6 +34,118 @@ type PacketInfo struct { Route stack.Route } +// Notification is the interface for receiving notification from the packet +// queue. +type Notification interface { + // WriteNotify will be called when a write happens to the queue. + WriteNotify() +} + +// NotificationHandle is an opaque handle to the registered notification target. +// It can be used to unregister the notification when no longer interested. +// +// +stateify savable +type NotificationHandle struct { + n Notification +} + +type queue struct { + // mu protects fields below. + mu sync.RWMutex + // c is the outbound packet channel. Sending to c should hold mu. + c chan PacketInfo + numWrite int + numRead int + notify []*NotificationHandle +} + +func (q *queue) Close() { + close(q.c) +} + +func (q *queue) Read() (PacketInfo, bool) { + q.mu.Lock() + defer q.mu.Unlock() + select { + case p := <-q.c: + q.numRead++ + return p, true + default: + return PacketInfo{}, false + } +} + +func (q *queue) ReadContext(ctx context.Context) (PacketInfo, bool) { + // We have to receive from channel without holding the lock, since it can + // block indefinitely. This will cause a window that numWrite - numRead + // produces a larger number, but won't go to negative. numWrite >= numRead + // still holds. + select { + case pkt := <-q.c: + q.mu.Lock() + defer q.mu.Unlock() + q.numRead++ + return pkt, true + case <-ctx.Done(): + return PacketInfo{}, false + } +} + +func (q *queue) Write(p PacketInfo) bool { + wrote := false + + // It's important to make sure nobody can see numWrite until we increment it, + // so numWrite >= numRead holds. + q.mu.Lock() + select { + case q.c <- p: + wrote = true + q.numWrite++ + default: + } + notify := q.notify + q.mu.Unlock() + + if wrote { + // Send notification outside of lock. + for _, h := range notify { + h.n.WriteNotify() + } + } + return wrote +} + +func (q *queue) Num() int { + q.mu.RLock() + defer q.mu.RUnlock() + n := q.numWrite - q.numRead + if n < 0 { + panic("numWrite < numRead") + } + return n +} + +func (q *queue) AddNotify(notify Notification) *NotificationHandle { + q.mu.Lock() + defer q.mu.Unlock() + h := &NotificationHandle{n: notify} + q.notify = append(q.notify, h) + return h +} + +func (q *queue) RemoveNotify(handle *NotificationHandle) { + q.mu.Lock() + defer q.mu.Unlock() + // Make a copy, since we reads the array outside of lock when notifying. + notify := make([]*NotificationHandle, 0, len(q.notify)) + for _, h := range q.notify { + if h != handle { + notify = append(notify, h) + } + } + q.notify = notify +} + // Endpoint is link layer endpoint that stores outbound packets in a channel // and allows injection of inbound packets. type Endpoint struct { @@ -41,14 +154,16 @@ type Endpoint struct { linkAddr tcpip.LinkAddress LinkEPCapabilities stack.LinkEndpointCapabilities - // c is where outbound packets are queued. - c chan PacketInfo + // Outbound packet queue. + q *queue } // New creates a new channel endpoint. func New(size int, mtu uint32, linkAddr tcpip.LinkAddress) *Endpoint { return &Endpoint{ - c: make(chan PacketInfo, size), + q: &queue{ + c: make(chan PacketInfo, size), + }, mtu: mtu, linkAddr: linkAddr, } @@ -57,43 +172,36 @@ func New(size int, mtu uint32, linkAddr tcpip.LinkAddress) *Endpoint { // Close closes e. Further packet injections will panic. Reads continue to // succeed until all packets are read. func (e *Endpoint) Close() { - close(e.c) + e.q.Close() } -// Read does non-blocking read for one packet from the outbound packet queue. +// Read does non-blocking read one packet from the outbound packet queue. func (e *Endpoint) Read() (PacketInfo, bool) { - select { - case pkt := <-e.c: - return pkt, true - default: - return PacketInfo{}, false - } + return e.q.Read() } // ReadContext does blocking read for one packet from the outbound packet queue. // It can be cancelled by ctx, and in this case, it returns false. func (e *Endpoint) ReadContext(ctx context.Context) (PacketInfo, bool) { - select { - case pkt := <-e.c: - return pkt, true - case <-ctx.Done(): - return PacketInfo{}, false - } + return e.q.ReadContext(ctx) } // Drain removes all outbound packets from the channel and counts them. func (e *Endpoint) Drain() int { c := 0 for { - select { - case <-e.c: - c++ - default: + if _, ok := e.Read(); !ok { return c } + c++ } } +// NumQueued returns the number of packet queued for outbound. +func (e *Endpoint) NumQueued() int { + return e.q.Num() +} + // InjectInbound injects an inbound packet. func (e *Endpoint) InjectInbound(protocol tcpip.NetworkProtocolNumber, pkt tcpip.PacketBuffer) { e.InjectLinkAddr(protocol, "", pkt) @@ -155,10 +263,7 @@ func (e *Endpoint) WritePacket(r *stack.Route, gso *stack.GSO, protocol tcpip.Ne Route: route, } - select { - case e.c <- p: - default: - } + e.q.Write(p) return nil } @@ -171,7 +276,6 @@ func (e *Endpoint) WritePackets(r *stack.Route, gso *stack.GSO, pkts []tcpip.Pac route.Release() payloadView := pkts[0].Data.ToView() n := 0 -packetLoop: for _, pkt := range pkts { off := pkt.DataOffset size := pkt.DataSize @@ -185,12 +289,10 @@ packetLoop: Route: route, } - select { - case e.c <- p: - n++ - default: - break packetLoop + if !e.q.Write(p) { + break } + n++ } return n, nil @@ -204,13 +306,21 @@ func (e *Endpoint) WriteRawPacket(vv buffer.VectorisedView) *tcpip.Error { GSO: nil, } - select { - case e.c <- p: - default: - } + e.q.Write(p) return nil } // Wait implements stack.LinkEndpoint.Wait. func (*Endpoint) Wait() {} + +// AddNotify adds a notification target for receiving event about outgoing +// packets. +func (e *Endpoint) AddNotify(notify Notification) *NotificationHandle { + return e.q.AddNotify(notify) +} + +// RemoveNotify removes handle from the list of notification targets. +func (e *Endpoint) RemoveNotify(handle *NotificationHandle) { + e.q.RemoveNotify(handle) +} diff --git a/pkg/tcpip/link/tun/BUILD b/pkg/tcpip/link/tun/BUILD index e5096ea38..e0db6cf54 100644 --- a/pkg/tcpip/link/tun/BUILD +++ b/pkg/tcpip/link/tun/BUILD @@ -4,6 +4,22 @@ package(licenses = ["notice"]) go_library( name = "tun", - srcs = ["tun_unsafe.go"], + srcs = [ + "device.go", + "protocol.go", + "tun_unsafe.go", + ], visibility = ["//visibility:public"], + deps = [ + "//pkg/abi/linux", + "//pkg/refs", + "//pkg/sync", + "//pkg/syserror", + "//pkg/tcpip", + "//pkg/tcpip/buffer", + "//pkg/tcpip/header", + "//pkg/tcpip/link/channel", + "//pkg/tcpip/stack", + "//pkg/waiter", + ], ) diff --git a/pkg/tcpip/link/tun/device.go b/pkg/tcpip/link/tun/device.go new file mode 100644 index 000000000..6ff47a742 --- /dev/null +++ b/pkg/tcpip/link/tun/device.go @@ -0,0 +1,352 @@ +// 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 tun + +import ( + "fmt" + + "gvisor.dev/gvisor/pkg/abi/linux" + "gvisor.dev/gvisor/pkg/refs" + "gvisor.dev/gvisor/pkg/sync" + "gvisor.dev/gvisor/pkg/syserror" + "gvisor.dev/gvisor/pkg/tcpip" + "gvisor.dev/gvisor/pkg/tcpip/buffer" + "gvisor.dev/gvisor/pkg/tcpip/header" + "gvisor.dev/gvisor/pkg/tcpip/link/channel" + "gvisor.dev/gvisor/pkg/tcpip/stack" + "gvisor.dev/gvisor/pkg/waiter" +) + +const ( + // drivers/net/tun.c:tun_net_init() + defaultDevMtu = 1500 + + // Queue length for outbound packet, arriving at fd side for read. Overflow + // causes packet drops. gVisor implementation-specific. + defaultDevOutQueueLen = 1024 +) + +var zeroMAC [6]byte + +// Device is an opened /dev/net/tun device. +// +// +stateify savable +type Device struct { + waiter.Queue + + mu sync.RWMutex `state:"nosave"` + endpoint *tunEndpoint + notifyHandle *channel.NotificationHandle + flags uint16 +} + +// beforeSave is invoked by stateify. +func (d *Device) beforeSave() { + d.mu.Lock() + defer d.mu.Unlock() + // TODO(b/110961832): Restore the device to stack. At this moment, the stack + // is not savable. + if d.endpoint != nil { + panic("/dev/net/tun does not support save/restore when a device is associated with it.") + } +} + +// Release implements fs.FileOperations.Release. +func (d *Device) Release() { + d.mu.Lock() + defer d.mu.Unlock() + + // Decrease refcount if there is an endpoint associated with this file. + if d.endpoint != nil { + d.endpoint.RemoveNotify(d.notifyHandle) + d.endpoint.DecRef() + d.endpoint = nil + } +} + +// SetIff services TUNSETIFF ioctl(2) request. +func (d *Device) SetIff(s *stack.Stack, name string, flags uint16) error { + d.mu.Lock() + defer d.mu.Unlock() + + if d.endpoint != nil { + return syserror.EINVAL + } + + // Input validations. + isTun := flags&linux.IFF_TUN != 0 + isTap := flags&linux.IFF_TAP != 0 + supportedFlags := uint16(linux.IFF_TUN | linux.IFF_TAP | linux.IFF_NO_PI) + if isTap && isTun || !isTap && !isTun || flags&^supportedFlags != 0 { + return syserror.EINVAL + } + + prefix := "tun" + if isTap { + prefix = "tap" + } + + endpoint, err := attachOrCreateNIC(s, name, prefix) + if err != nil { + return syserror.EINVAL + } + + d.endpoint = endpoint + d.notifyHandle = d.endpoint.AddNotify(d) + d.flags = flags + return nil +} + +func attachOrCreateNIC(s *stack.Stack, name, prefix string) (*tunEndpoint, error) { + for { + // 1. Try to attach to an existing NIC. + if name != "" { + if nic, found := s.GetNICByName(name); found { + endpoint, ok := nic.LinkEndpoint().(*tunEndpoint) + if !ok { + // Not a NIC created by tun device. + return nil, syserror.EOPNOTSUPP + } + if !endpoint.TryIncRef() { + // Race detected: NIC got deleted in between. + continue + } + return endpoint, nil + } + } + + // 2. Creating a new NIC. + id := tcpip.NICID(s.UniqueID()) + endpoint := &tunEndpoint{ + Endpoint: channel.New(defaultDevOutQueueLen, defaultDevMtu, ""), + stack: s, + nicID: id, + name: name, + } + if endpoint.name == "" { + endpoint.name = fmt.Sprintf("%s%d", prefix, id) + } + err := s.CreateNICWithOptions(endpoint.nicID, endpoint, stack.NICOptions{ + Name: endpoint.name, + }) + switch err { + case nil: + return endpoint, nil + case tcpip.ErrDuplicateNICID: + // Race detected: A NIC has been created in between. + continue + default: + return nil, syserror.EINVAL + } + } +} + +// Write inject one inbound packet to the network interface. +func (d *Device) Write(data []byte) (int64, error) { + d.mu.RLock() + endpoint := d.endpoint + d.mu.RUnlock() + if endpoint == nil { + return 0, syserror.EBADFD + } + if !endpoint.IsAttached() { + return 0, syserror.EIO + } + + dataLen := int64(len(data)) + + // Packet information. + var pktInfoHdr PacketInfoHeader + if !d.hasFlags(linux.IFF_NO_PI) { + if len(data) < PacketInfoHeaderSize { + // Ignore bad packet. + return dataLen, nil + } + pktInfoHdr = PacketInfoHeader(data[:PacketInfoHeaderSize]) + data = data[PacketInfoHeaderSize:] + } + + // Ethernet header (TAP only). + var ethHdr header.Ethernet + if d.hasFlags(linux.IFF_TAP) { + if len(data) < header.EthernetMinimumSize { + // Ignore bad packet. + return dataLen, nil + } + ethHdr = header.Ethernet(data[:header.EthernetMinimumSize]) + data = data[header.EthernetMinimumSize:] + } + + // Try to determine network protocol number, default zero. + var protocol tcpip.NetworkProtocolNumber + switch { + case pktInfoHdr != nil: + protocol = pktInfoHdr.Protocol() + case ethHdr != nil: + protocol = ethHdr.Type() + } + + // Try to determine remote link address, default zero. + var remote tcpip.LinkAddress + switch { + case ethHdr != nil: + remote = ethHdr.SourceAddress() + default: + remote = tcpip.LinkAddress(zeroMAC[:]) + } + + pkt := tcpip.PacketBuffer{ + Data: buffer.View(data).ToVectorisedView(), + } + if ethHdr != nil { + pkt.LinkHeader = buffer.View(ethHdr) + } + endpoint.InjectLinkAddr(protocol, remote, pkt) + return dataLen, nil +} + +// Read reads one outgoing packet from the network interface. +func (d *Device) Read() ([]byte, error) { + d.mu.RLock() + endpoint := d.endpoint + d.mu.RUnlock() + if endpoint == nil { + return nil, syserror.EBADFD + } + + for { + info, ok := endpoint.Read() + if !ok { + return nil, syserror.ErrWouldBlock + } + + v, ok := d.encodePkt(&info) + if !ok { + // Ignore unsupported packet. + continue + } + return v, nil + } +} + +// encodePkt encodes packet for fd side. +func (d *Device) encodePkt(info *channel.PacketInfo) (buffer.View, bool) { + var vv buffer.VectorisedView + + // Packet information. + if !d.hasFlags(linux.IFF_NO_PI) { + hdr := make(PacketInfoHeader, PacketInfoHeaderSize) + hdr.Encode(&PacketInfoFields{ + Protocol: info.Proto, + }) + vv.AppendView(buffer.View(hdr)) + } + + // If the packet does not already have link layer header, and the route + // does not exist, we can't compute it. This is possibly a raw packet, tun + // device doesn't support this at the moment. + if info.Pkt.LinkHeader == nil && info.Route.RemoteLinkAddress == "" { + return nil, false + } + + // Ethernet header (TAP only). + if d.hasFlags(linux.IFF_TAP) { + // Add ethernet header if not provided. + if info.Pkt.LinkHeader == nil { + hdr := &header.EthernetFields{ + SrcAddr: info.Route.LocalLinkAddress, + DstAddr: info.Route.RemoteLinkAddress, + Type: info.Proto, + } + if hdr.SrcAddr == "" { + hdr.SrcAddr = d.endpoint.LinkAddress() + } + + eth := make(header.Ethernet, header.EthernetMinimumSize) + eth.Encode(hdr) + vv.AppendView(buffer.View(eth)) + } else { + vv.AppendView(info.Pkt.LinkHeader) + } + } + + // Append upper headers. + vv.AppendView(buffer.View(info.Pkt.Header.View()[len(info.Pkt.LinkHeader):])) + // Append data payload. + vv.Append(info.Pkt.Data) + + return vv.ToView(), true +} + +// Name returns the name of the attached network interface. Empty string if +// unattached. +func (d *Device) Name() string { + d.mu.RLock() + defer d.mu.RUnlock() + if d.endpoint != nil { + return d.endpoint.name + } + return "" +} + +// Flags returns the flags set for d. Zero value if unset. +func (d *Device) Flags() uint16 { + d.mu.RLock() + defer d.mu.RUnlock() + return d.flags +} + +func (d *Device) hasFlags(flags uint16) bool { + return d.flags&flags == flags +} + +// Readiness implements watier.Waitable.Readiness. +func (d *Device) Readiness(mask waiter.EventMask) waiter.EventMask { + if mask&waiter.EventIn != 0 { + d.mu.RLock() + endpoint := d.endpoint + d.mu.RUnlock() + if endpoint != nil && endpoint.NumQueued() == 0 { + mask &= ^waiter.EventIn + } + } + return mask & (waiter.EventIn | waiter.EventOut) +} + +// WriteNotify implements channel.Notification.WriteNotify. +func (d *Device) WriteNotify() { + d.Notify(waiter.EventIn) +} + +// tunEndpoint is the link endpoint for the NIC created by the tun device. +// +// It is ref-counted as multiple opening files can attach to the same NIC. +// The last owner is responsible for deleting the NIC. +type tunEndpoint struct { + *channel.Endpoint + + refs.AtomicRefCount + + stack *stack.Stack + nicID tcpip.NICID + name string +} + +// DecRef decrements refcount of e, removes NIC if refcount goes to 0. +func (e *tunEndpoint) DecRef() { + e.DecRefWithDestructor(func() { + e.stack.RemoveNIC(e.nicID) + }) +} diff --git a/pkg/tcpip/link/tun/protocol.go b/pkg/tcpip/link/tun/protocol.go new file mode 100644 index 000000000..89d9d91a9 --- /dev/null +++ b/pkg/tcpip/link/tun/protocol.go @@ -0,0 +1,56 @@ +// 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 tun + +import ( + "encoding/binary" + + "gvisor.dev/gvisor/pkg/tcpip" +) + +const ( + // PacketInfoHeaderSize is the size of the packet information header. + PacketInfoHeaderSize = 4 + + offsetFlags = 0 + offsetProtocol = 2 +) + +// PacketInfoFields contains fields sent through the wire if IFF_NO_PI flag is +// not set. +type PacketInfoFields struct { + Flags uint16 + Protocol tcpip.NetworkProtocolNumber +} + +// PacketInfoHeader is the wire representation of the packet information sent if +// IFF_NO_PI flag is not set. +type PacketInfoHeader []byte + +// Encode encodes f into h. +func (h PacketInfoHeader) Encode(f *PacketInfoFields) { + binary.BigEndian.PutUint16(h[offsetFlags:][:2], f.Flags) + binary.BigEndian.PutUint16(h[offsetProtocol:][:2], uint16(f.Protocol)) +} + +// Flags returns the flag field in h. +func (h PacketInfoHeader) Flags() uint16 { + return binary.BigEndian.Uint16(h[offsetFlags:]) +} + +// Protocol returns the protocol field in h. +func (h PacketInfoHeader) Protocol() tcpip.NetworkProtocolNumber { + return tcpip.NetworkProtocolNumber(binary.BigEndian.Uint16(h[offsetProtocol:])) +} diff --git a/pkg/tcpip/stack/nic.go b/pkg/tcpip/stack/nic.go index 862954ab2..46d3a6646 100644 --- a/pkg/tcpip/stack/nic.go +++ b/pkg/tcpip/stack/nic.go @@ -298,6 +298,33 @@ func (n *NIC) enable() *tcpip.Error { return nil } +// remove detaches NIC from the link endpoint, and marks existing referenced +// network endpoints expired. This guarantees no packets between this NIC and +// the network stack. +func (n *NIC) remove() *tcpip.Error { + n.mu.Lock() + defer n.mu.Unlock() + + // Detach from link endpoint, so no packet comes in. + n.linkEP.Attach(nil) + + // Remove permanent and permanentTentative addresses, so no packet goes out. + var errs []*tcpip.Error + for nid, ref := range n.mu.endpoints { + switch ref.getKind() { + case permanentTentative, permanent: + if err := n.removePermanentAddressLocked(nid.LocalAddress); err != nil { + errs = append(errs, err) + } + } + } + if len(errs) > 0 { + return errs[0] + } + + return nil +} + // becomeIPv6Router transitions n into an IPv6 router. // // When transitioning into an IPv6 router, host-only state (NDP discovered @@ -1302,6 +1329,11 @@ func (n *NIC) Stack() *Stack { return n.stack } +// LinkEndpoint returns the link endpoint of n. +func (n *NIC) LinkEndpoint() LinkEndpoint { + return n.linkEP +} + // isAddrTentative returns true if addr is tentative on n. // // Note that if addr is not associated with n, then this function will return diff --git a/pkg/tcpip/stack/stack.go b/pkg/tcpip/stack/stack.go index f0ed76fbe..900dd46c5 100644 --- a/pkg/tcpip/stack/stack.go +++ b/pkg/tcpip/stack/stack.go @@ -916,6 +916,18 @@ func (s *Stack) CreateNIC(id tcpip.NICID, ep LinkEndpoint) *tcpip.Error { return s.CreateNICWithOptions(id, ep, NICOptions{}) } +// GetNICByName gets the NIC specified by name. +func (s *Stack) GetNICByName(name string) (*NIC, bool) { + s.mu.RLock() + defer s.mu.RUnlock() + for _, nic := range s.nics { + if nic.Name() == name { + return nic, true + } + } + return nil, false +} + // EnableNIC enables the given NIC so that the link-layer endpoint can start // delivering packets to it. func (s *Stack) EnableNIC(id tcpip.NICID) *tcpip.Error { @@ -956,6 +968,33 @@ func (s *Stack) CheckNIC(id tcpip.NICID) bool { return nic.enabled() } +// RemoveNIC removes NIC and all related routes from the network stack. +func (s *Stack) RemoveNIC(id tcpip.NICID) *tcpip.Error { + s.mu.Lock() + defer s.mu.Unlock() + + nic, ok := s.nics[id] + if !ok { + return tcpip.ErrUnknownNICID + } + delete(s.nics, id) + + // Remove routes in-place. n tracks the number of routes written. + n := 0 + for i, r := range s.routeTable { + if r.NIC != id { + // Keep this route. + if i > n { + s.routeTable[n] = r + } + n++ + } + } + s.routeTable = s.routeTable[:n] + + return nic.remove() +} + // NICAddressRanges returns a map of NICIDs to their associated subnets. func (s *Stack) NICAddressRanges() map[tcpip.NICID][]tcpip.Subnet { s.mu.RLock() diff --git a/test/syscalls/BUILD b/test/syscalls/BUILD index d1977d4de..3518e862d 100644 --- a/test/syscalls/BUILD +++ b/test/syscalls/BUILD @@ -678,6 +678,8 @@ syscall_test( test = "//test/syscalls/linux:truncate_test", ) +syscall_test(test = "//test/syscalls/linux:tuntap_test") + syscall_test(test = "//test/syscalls/linux:udp_bind_test") syscall_test( diff --git a/test/syscalls/linux/BUILD b/test/syscalls/linux/BUILD index aa303af84..704bae17b 100644 --- a/test/syscalls/linux/BUILD +++ b/test/syscalls/linux/BUILD @@ -131,6 +131,17 @@ cc_library( ], ) +cc_library( + name = "socket_netlink_route_util", + testonly = 1, + srcs = ["socket_netlink_route_util.cc"], + hdrs = ["socket_netlink_route_util.h"], + deps = [ + ":socket_netlink_util", + "@com_google_absl//absl/types:optional", + ], +) + cc_library( name = "socket_test_util", testonly = 1, @@ -3430,6 +3441,25 @@ cc_binary( ], ) +cc_binary( + name = "tuntap_test", + testonly = 1, + srcs = ["tuntap.cc"], + linkstatic = 1, + deps = [ + ":socket_test_util", + gtest, + "//test/syscalls/linux:socket_netlink_route_util", + "//test/util:capability_util", + "//test/util:file_descriptor", + "//test/util:fs_util", + "//test/util:posix_error", + "//test/util:test_main", + "//test/util:test_util", + "@com_google_absl//absl/strings", + ], +) + cc_library( name = "udp_socket_test_cases", testonly = 1, diff --git a/test/syscalls/linux/dev.cc b/test/syscalls/linux/dev.cc index 4dd302eed..4e473268c 100644 --- a/test/syscalls/linux/dev.cc +++ b/test/syscalls/linux/dev.cc @@ -153,6 +153,13 @@ TEST(DevTest, TTYExists) { EXPECT_EQ(statbuf.st_mode, S_IFCHR | 0666); } +TEST(DevTest, NetTunExists) { + struct stat statbuf = {}; + ASSERT_THAT(stat("/dev/net/tun", &statbuf), SyscallSucceeds()); + // Check that it's a character device with rw-rw-rw- permissions. + EXPECT_EQ(statbuf.st_mode, S_IFCHR | 0666); +} + } // namespace } // namespace testing diff --git a/test/syscalls/linux/socket_netlink_route_util.cc b/test/syscalls/linux/socket_netlink_route_util.cc new file mode 100644 index 000000000..53eb3b6b2 --- /dev/null +++ b/test/syscalls/linux/socket_netlink_route_util.cc @@ -0,0 +1,163 @@ +// 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. + +#include "test/syscalls/linux/socket_netlink_route_util.h" + +#include +#include +#include + +#include "absl/types/optional.h" +#include "test/syscalls/linux/socket_netlink_util.h" + +namespace gvisor { +namespace testing { +namespace { + +constexpr uint32_t kSeq = 12345; + +} // namespace + +PosixError DumpLinks( + const FileDescriptor& fd, uint32_t seq, + const std::function& fn) { + struct request { + struct nlmsghdr hdr; + struct ifinfomsg ifm; + }; + + struct request req = {}; + req.hdr.nlmsg_len = sizeof(req); + req.hdr.nlmsg_type = RTM_GETLINK; + req.hdr.nlmsg_flags = NLM_F_REQUEST | NLM_F_DUMP; + req.hdr.nlmsg_seq = seq; + req.ifm.ifi_family = AF_UNSPEC; + + return NetlinkRequestResponse(fd, &req, sizeof(req), fn, false); +} + +PosixErrorOr> DumpLinks() { + ASSIGN_OR_RETURN_ERRNO(FileDescriptor fd, NetlinkBoundSocket(NETLINK_ROUTE)); + + std::vector links; + RETURN_IF_ERRNO(DumpLinks(fd, kSeq, [&](const struct nlmsghdr* hdr) { + if (hdr->nlmsg_type != RTM_NEWLINK || + hdr->nlmsg_len < NLMSG_SPACE(sizeof(struct ifinfomsg))) { + return; + } + const struct ifinfomsg* msg = + reinterpret_cast(NLMSG_DATA(hdr)); + const auto* rta = FindRtAttr(hdr, msg, IFLA_IFNAME); + if (rta == nullptr) { + // Ignore links that do not have a name. + return; + } + + links.emplace_back(); + links.back().index = msg->ifi_index; + links.back().type = msg->ifi_type; + links.back().name = + std::string(reinterpret_cast(RTA_DATA(rta))); + })); + return links; +} + +PosixErrorOr> FindLoopbackLink() { + ASSIGN_OR_RETURN_ERRNO(auto links, DumpLinks()); + for (const auto& link : links) { + if (link.type == ARPHRD_LOOPBACK) { + return absl::optional(link); + } + } + return absl::optional(); +} + +PosixError LinkAddLocalAddr(int index, int family, int prefixlen, + const void* addr, int addrlen) { + ASSIGN_OR_RETURN_ERRNO(FileDescriptor fd, NetlinkBoundSocket(NETLINK_ROUTE)); + + struct request { + struct nlmsghdr hdr; + struct ifaddrmsg ifaddr; + char attrbuf[512]; + }; + + struct request req = {}; + req.hdr.nlmsg_len = NLMSG_LENGTH(sizeof(req.ifaddr)); + req.hdr.nlmsg_type = RTM_NEWADDR; + req.hdr.nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK; + req.hdr.nlmsg_seq = kSeq; + req.ifaddr.ifa_index = index; + req.ifaddr.ifa_family = family; + req.ifaddr.ifa_prefixlen = prefixlen; + + struct rtattr* rta = reinterpret_cast( + reinterpret_cast(&req) + NLMSG_ALIGN(req.hdr.nlmsg_len)); + rta->rta_type = IFA_LOCAL; + rta->rta_len = RTA_LENGTH(addrlen); + req.hdr.nlmsg_len = NLMSG_ALIGN(req.hdr.nlmsg_len) + RTA_LENGTH(addrlen); + memcpy(RTA_DATA(rta), addr, addrlen); + + return NetlinkRequestAckOrError(fd, kSeq, &req, req.hdr.nlmsg_len); +} + +PosixError LinkChangeFlags(int index, unsigned int flags, unsigned int change) { + ASSIGN_OR_RETURN_ERRNO(FileDescriptor fd, NetlinkBoundSocket(NETLINK_ROUTE)); + + struct request { + struct nlmsghdr hdr; + struct ifinfomsg ifinfo; + char pad[NLMSG_ALIGNTO]; + }; + + struct request req = {}; + req.hdr.nlmsg_len = NLMSG_LENGTH(sizeof(req.ifinfo)); + req.hdr.nlmsg_type = RTM_NEWLINK; + req.hdr.nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK; + req.hdr.nlmsg_seq = kSeq; + req.ifinfo.ifi_index = index; + req.ifinfo.ifi_flags = flags; + req.ifinfo.ifi_change = change; + + return NetlinkRequestAckOrError(fd, kSeq, &req, req.hdr.nlmsg_len); +} + +PosixError LinkSetMacAddr(int index, const void* addr, int addrlen) { + ASSIGN_OR_RETURN_ERRNO(FileDescriptor fd, NetlinkBoundSocket(NETLINK_ROUTE)); + + struct request { + struct nlmsghdr hdr; + struct ifinfomsg ifinfo; + char attrbuf[512]; + }; + + struct request req = {}; + req.hdr.nlmsg_len = NLMSG_LENGTH(sizeof(req.ifinfo)); + req.hdr.nlmsg_type = RTM_NEWLINK; + req.hdr.nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK; + req.hdr.nlmsg_seq = kSeq; + req.ifinfo.ifi_index = index; + + struct rtattr* rta = reinterpret_cast( + reinterpret_cast(&req) + NLMSG_ALIGN(req.hdr.nlmsg_len)); + rta->rta_type = IFLA_ADDRESS; + rta->rta_len = RTA_LENGTH(addrlen); + req.hdr.nlmsg_len = NLMSG_ALIGN(req.hdr.nlmsg_len) + RTA_LENGTH(addrlen); + memcpy(RTA_DATA(rta), addr, addrlen); + + return NetlinkRequestAckOrError(fd, kSeq, &req, req.hdr.nlmsg_len); +} + +} // namespace testing +} // namespace gvisor diff --git a/test/syscalls/linux/socket_netlink_route_util.h b/test/syscalls/linux/socket_netlink_route_util.h new file mode 100644 index 000000000..2c018e487 --- /dev/null +++ b/test/syscalls/linux/socket_netlink_route_util.h @@ -0,0 +1,55 @@ +// 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. + +#ifndef GVISOR_TEST_SYSCALLS_LINUX_SOCKET_NETLINK_ROUTE_UTIL_H_ +#define GVISOR_TEST_SYSCALLS_LINUX_SOCKET_NETLINK_ROUTE_UTIL_H_ + +#include +#include + +#include + +#include "absl/types/optional.h" +#include "test/syscalls/linux/socket_netlink_util.h" + +namespace gvisor { +namespace testing { + +struct Link { + int index; + int16_t type; + std::string name; +}; + +PosixError DumpLinks(const FileDescriptor& fd, uint32_t seq, + const std::function& fn); + +PosixErrorOr> DumpLinks(); + +PosixErrorOr> FindLoopbackLink(); + +// LinkAddLocalAddr sets IFA_LOCAL attribute on the interface. +PosixError LinkAddLocalAddr(int index, int family, int prefixlen, + const void* addr, int addrlen); + +// LinkChangeFlags changes interface flags. E.g. IFF_UP. +PosixError LinkChangeFlags(int index, unsigned int flags, unsigned int change); + +// LinkSetMacAddr sets IFLA_ADDRESS attribute of the interface. +PosixError LinkSetMacAddr(int index, const void* addr, int addrlen); + +} // namespace testing +} // namespace gvisor + +#endif // GVISOR_TEST_SYSCALLS_LINUX_SOCKET_NETLINK_ROUTE_UTIL_H_ diff --git a/test/syscalls/linux/tuntap.cc b/test/syscalls/linux/tuntap.cc new file mode 100644 index 000000000..f6ac9d7b8 --- /dev/null +++ b/test/syscalls/linux/tuntap.cc @@ -0,0 +1,346 @@ +// Copyright 2019 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. + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "gmock/gmock.h" +#include "gtest/gtest.h" +#include "absl/strings/ascii.h" +#include "absl/strings/str_split.h" +#include "test/syscalls/linux/socket_netlink_route_util.h" +#include "test/syscalls/linux/socket_test_util.h" +#include "test/util/capability_util.h" +#include "test/util/file_descriptor.h" +#include "test/util/fs_util.h" +#include "test/util/posix_error.h" +#include "test/util/test_util.h" + +namespace gvisor { +namespace testing { +namespace { + +constexpr int kIPLen = 4; + +constexpr const char kDevNetTun[] = "/dev/net/tun"; +constexpr const char kTapName[] = "tap0"; + +constexpr const uint8_t kMacA[ETH_ALEN] = {0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA}; +constexpr const uint8_t kMacB[ETH_ALEN] = {0xBB, 0xBB, 0xBB, 0xBB, 0xBB, 0xBB}; + +PosixErrorOr> DumpLinkNames() { + ASSIGN_OR_RETURN_ERRNO(auto links, DumpLinks()); + std::set names; + for (const auto& link : links) { + names.emplace(link.name); + } + return names; +} + +PosixErrorOr> GetLinkByName(const std::string& name) { + ASSIGN_OR_RETURN_ERRNO(auto links, DumpLinks()); + for (const auto& link : links) { + if (link.name == name) { + return absl::optional(link); + } + } + return absl::optional(); +} + +struct pihdr { + uint16_t pi_flags; + uint16_t pi_protocol; +} __attribute__((packed)); + +struct ping_pkt { + pihdr pi; + struct ethhdr eth; + struct iphdr ip; + struct icmphdr icmp; + char payload[64]; +} __attribute__((packed)); + +ping_pkt CreatePingPacket(const uint8_t srcmac[ETH_ALEN], const char* srcip, + const uint8_t dstmac[ETH_ALEN], const char* dstip) { + ping_pkt pkt = {}; + + pkt.pi.pi_protocol = htons(ETH_P_IP); + + memcpy(pkt.eth.h_dest, dstmac, sizeof(pkt.eth.h_dest)); + memcpy(pkt.eth.h_source, srcmac, sizeof(pkt.eth.h_source)); + pkt.eth.h_proto = htons(ETH_P_IP); + + pkt.ip.ihl = 5; + pkt.ip.version = 4; + pkt.ip.tos = 0; + pkt.ip.tot_len = htons(sizeof(struct iphdr) + sizeof(struct icmphdr) + + sizeof(pkt.payload)); + pkt.ip.id = 1; + pkt.ip.frag_off = 1 << 6; // Do not fragment + pkt.ip.ttl = 64; + pkt.ip.protocol = IPPROTO_ICMP; + inet_pton(AF_INET, dstip, &pkt.ip.daddr); + inet_pton(AF_INET, srcip, &pkt.ip.saddr); + pkt.ip.check = IPChecksum(pkt.ip); + + pkt.icmp.type = ICMP_ECHO; + pkt.icmp.code = 0; + pkt.icmp.checksum = 0; + pkt.icmp.un.echo.sequence = 1; + pkt.icmp.un.echo.id = 1; + + strncpy(pkt.payload, "abcd", sizeof(pkt.payload)); + pkt.icmp.checksum = ICMPChecksum(pkt.icmp, pkt.payload, sizeof(pkt.payload)); + + return pkt; +} + +struct arp_pkt { + pihdr pi; + struct ethhdr eth; + struct arphdr arp; + uint8_t arp_sha[ETH_ALEN]; + uint8_t arp_spa[kIPLen]; + uint8_t arp_tha[ETH_ALEN]; + uint8_t arp_tpa[kIPLen]; +} __attribute__((packed)); + +std::string CreateArpPacket(const uint8_t srcmac[ETH_ALEN], const char* srcip, + const uint8_t dstmac[ETH_ALEN], const char* dstip) { + std::string buffer; + buffer.resize(sizeof(arp_pkt)); + + arp_pkt* pkt = reinterpret_cast(&buffer[0]); + { + pkt->pi.pi_protocol = htons(ETH_P_ARP); + + memcpy(pkt->eth.h_dest, kMacA, sizeof(pkt->eth.h_dest)); + memcpy(pkt->eth.h_source, kMacB, sizeof(pkt->eth.h_source)); + pkt->eth.h_proto = htons(ETH_P_ARP); + + pkt->arp.ar_hrd = htons(ARPHRD_ETHER); + pkt->arp.ar_pro = htons(ETH_P_IP); + pkt->arp.ar_hln = ETH_ALEN; + pkt->arp.ar_pln = kIPLen; + pkt->arp.ar_op = htons(ARPOP_REPLY); + + memcpy(pkt->arp_sha, srcmac, sizeof(pkt->arp_sha)); + inet_pton(AF_INET, srcip, pkt->arp_spa); + memcpy(pkt->arp_tha, dstmac, sizeof(pkt->arp_tha)); + inet_pton(AF_INET, dstip, pkt->arp_tpa); + } + return buffer; +} + +} // namespace + +class TuntapTest : public ::testing::Test { + protected: + void TearDown() override { + if (ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_NET_ADMIN))) { + // Bring back capability if we had dropped it in test case. + ASSERT_NO_ERRNO(SetCapability(CAP_NET_ADMIN, true)); + } + } +}; + +TEST_F(TuntapTest, CreateInterfaceNoCap) { + SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_NET_ADMIN))); + + ASSERT_NO_ERRNO(SetCapability(CAP_NET_ADMIN, false)); + + FileDescriptor fd = ASSERT_NO_ERRNO_AND_VALUE(Open(kDevNetTun, O_RDWR)); + + struct ifreq ifr = {}; + ifr.ifr_flags = IFF_TAP; + strncpy(ifr.ifr_name, kTapName, IFNAMSIZ); + + EXPECT_THAT(ioctl(fd.get(), TUNSETIFF, &ifr), SyscallFailsWithErrno(EPERM)); +} + +TEST_F(TuntapTest, CreateFixedNameInterface) { + SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_NET_ADMIN))); + + FileDescriptor fd = ASSERT_NO_ERRNO_AND_VALUE(Open(kDevNetTun, O_RDWR)); + + struct ifreq ifr_set = {}; + ifr_set.ifr_flags = IFF_TAP; + strncpy(ifr_set.ifr_name, kTapName, IFNAMSIZ); + EXPECT_THAT(ioctl(fd.get(), TUNSETIFF, &ifr_set), + SyscallSucceedsWithValue(0)); + + struct ifreq ifr_get = {}; + EXPECT_THAT(ioctl(fd.get(), TUNGETIFF, &ifr_get), + SyscallSucceedsWithValue(0)); + + struct ifreq ifr_expect = ifr_set; + // See __tun_chr_ioctl() in net/drivers/tun.c. + ifr_expect.ifr_flags |= IFF_NOFILTER; + + EXPECT_THAT(DumpLinkNames(), + IsPosixErrorOkAndHolds(::testing::Contains(kTapName))); + EXPECT_THAT(memcmp(&ifr_expect, &ifr_get, sizeof(ifr_get)), ::testing::Eq(0)); +} + +TEST_F(TuntapTest, CreateInterface) { + SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_NET_ADMIN))); + + FileDescriptor fd = ASSERT_NO_ERRNO_AND_VALUE(Open(kDevNetTun, O_RDWR)); + + struct ifreq ifr = {}; + ifr.ifr_flags = IFF_TAP; + // Empty ifr.ifr_name. Let kernel assign. + + EXPECT_THAT(ioctl(fd.get(), TUNSETIFF, &ifr), SyscallSucceedsWithValue(0)); + + struct ifreq ifr_get = {}; + EXPECT_THAT(ioctl(fd.get(), TUNGETIFF, &ifr_get), + SyscallSucceedsWithValue(0)); + + std::string ifname = ifr_get.ifr_name; + EXPECT_THAT(ifname, ::testing::StartsWith("tap")); + EXPECT_THAT(DumpLinkNames(), + IsPosixErrorOkAndHolds(::testing::Contains(ifname))); +} + +TEST_F(TuntapTest, InvalidReadWrite) { + SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_NET_ADMIN))); + + FileDescriptor fd = ASSERT_NO_ERRNO_AND_VALUE(Open(kDevNetTun, O_RDWR)); + + char buf[128] = {}; + EXPECT_THAT(read(fd.get(), buf, sizeof(buf)), SyscallFailsWithErrno(EBADFD)); + EXPECT_THAT(write(fd.get(), buf, sizeof(buf)), SyscallFailsWithErrno(EBADFD)); +} + +TEST_F(TuntapTest, WriteToDownDevice) { + SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_NET_ADMIN))); + + // FIXME: gVisor always creates enabled/up'd interfaces. + SKIP_IF(IsRunningOnGvisor()); + + FileDescriptor fd = ASSERT_NO_ERRNO_AND_VALUE(Open(kDevNetTun, O_RDWR)); + + // Device created should be down by default. + struct ifreq ifr = {}; + ifr.ifr_flags = IFF_TAP; + EXPECT_THAT(ioctl(fd.get(), TUNSETIFF, &ifr), SyscallSucceedsWithValue(0)); + + char buf[128] = {}; + EXPECT_THAT(write(fd.get(), buf, sizeof(buf)), SyscallFailsWithErrno(EIO)); +} + +// This test sets up a TAP device and pings kernel by sending ICMP echo request. +// +// It works as the following: +// * Open /dev/net/tun, and create kTapName interface. +// * Use rtnetlink to do initial setup of the interface: +// * Assign IP address 10.0.0.1/24 to kernel. +// * MAC address: kMacA +// * Bring up the interface. +// * Send an ICMP echo reqest (ping) packet from 10.0.0.2 (kMacB) to kernel. +// * Loop to receive packets from TAP device/fd: +// * If packet is an ICMP echo reply, it stops and passes the test. +// * If packet is an ARP request, it responds with canned reply and resends +// the +// ICMP request packet. +TEST_F(TuntapTest, PingKernel) { + SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_NET_ADMIN))); + + // Interface creation. + FileDescriptor fd = ASSERT_NO_ERRNO_AND_VALUE(Open(kDevNetTun, O_RDWR)); + + struct ifreq ifr_set = {}; + ifr_set.ifr_flags = IFF_TAP; + strncpy(ifr_set.ifr_name, kTapName, IFNAMSIZ); + EXPECT_THAT(ioctl(fd.get(), TUNSETIFF, &ifr_set), + SyscallSucceedsWithValue(0)); + + absl::optional link = + ASSERT_NO_ERRNO_AND_VALUE(GetLinkByName(kTapName)); + ASSERT_TRUE(link.has_value()); + + // Interface setup. + struct in_addr addr; + inet_pton(AF_INET, "10.0.0.1", &addr); + EXPECT_NO_ERRNO(LinkAddLocalAddr(link->index, AF_INET, /*prefixlen=*/24, + &addr, sizeof(addr))); + + if (!IsRunningOnGvisor()) { + // FIXME: gVisor doesn't support setting MAC address on interfaces yet. + EXPECT_NO_ERRNO(LinkSetMacAddr(link->index, kMacA, sizeof(kMacA))); + + // FIXME: gVisor always creates enabled/up'd interfaces. + EXPECT_NO_ERRNO(LinkChangeFlags(link->index, IFF_UP, IFF_UP)); + } + + ping_pkt ping_req = CreatePingPacket(kMacB, "10.0.0.2", kMacA, "10.0.0.1"); + std::string arp_rep = CreateArpPacket(kMacB, "10.0.0.2", kMacA, "10.0.0.1"); + + // Send ping, this would trigger an ARP request on Linux. + EXPECT_THAT(write(fd.get(), &ping_req, sizeof(ping_req)), + SyscallSucceedsWithValue(sizeof(ping_req))); + + // Receive loop to process inbound packets. + struct inpkt { + union { + pihdr pi; + ping_pkt ping; + arp_pkt arp; + }; + }; + while (1) { + inpkt r = {}; + int n = read(fd.get(), &r, sizeof(r)); + EXPECT_THAT(n, SyscallSucceeds()); + + if (n < sizeof(pihdr)) { + std::cerr << "Ignored packet, protocol: " << r.pi.pi_protocol + << " len: " << n << std::endl; + continue; + } + + // Process ARP packet. + if (n >= sizeof(arp_pkt) && r.pi.pi_protocol == htons(ETH_P_ARP)) { + // Respond with canned ARP reply. + EXPECT_THAT(write(fd.get(), arp_rep.data(), arp_rep.size()), + SyscallSucceedsWithValue(arp_rep.size())); + // First ping request might have been dropped due to mac address not in + // ARP cache. Send it again. + EXPECT_THAT(write(fd.get(), &ping_req, sizeof(ping_req)), + SyscallSucceedsWithValue(sizeof(ping_req))); + } + + // Process ping response packet. + if (n >= sizeof(ping_pkt) && r.pi.pi_protocol == ping_req.pi.pi_protocol && + r.ping.ip.protocol == ping_req.ip.protocol && + !memcmp(&r.ping.ip.saddr, &ping_req.ip.daddr, kIPLen) && + !memcmp(&r.ping.ip.daddr, &ping_req.ip.saddr, kIPLen) && + r.ping.icmp.type == 0 && r.ping.icmp.code == 0) { + // Ends and passes the test. + break; + } + } +} + +} // namespace testing +} // namespace gvisor -- cgit v1.2.3