diff options
Diffstat (limited to 'pkg/sentry')
| -rw-r--r-- | pkg/sentry/fs/host/socket.go | 4 | ||||
| -rw-r--r-- | pkg/sentry/fs/host/socket_iovec.go | 4 | ||||
| -rw-r--r-- | pkg/sentry/fs/host/socket_unsafe.go | 4 | ||||
| -rw-r--r-- | pkg/sentry/fsimpl/host/BUILD | 10 | ||||
| -rw-r--r-- | pkg/sentry/fsimpl/host/host.go | 57 | ||||
| -rw-r--r-- | pkg/sentry/fsimpl/host/socket.go | 397 | ||||
| -rw-r--r-- | pkg/sentry/fsimpl/host/socket_iovec.go | 113 | ||||
| -rw-r--r-- | pkg/sentry/fsimpl/host/socket_unsafe.go | 101 | ||||
| -rw-r--r-- | pkg/sentry/fsimpl/sockfs/sockfs.go | 20 | ||||
| -rw-r--r-- | pkg/sentry/socket/unix/BUILD | 1 | ||||
| -rw-r--r-- | pkg/sentry/socket/unix/unix_vfs2.go | 42 |
11 files changed, 698 insertions, 55 deletions
diff --git a/pkg/sentry/fs/host/socket.go b/pkg/sentry/fs/host/socket.go index 06fc2d80a..b6e94583e 100644 --- a/pkg/sentry/fs/host/socket.go +++ b/pkg/sentry/fs/host/socket.go @@ -37,6 +37,8 @@ import ( "gvisor.dev/gvisor/pkg/waiter" ) +// LINT.IfChange + // maxSendBufferSize is the maximum host send buffer size allowed for endpoint. // // N.B. 8MB is the default maximum on Linux (2 * sysctl_wmem_max). @@ -388,3 +390,5 @@ func (c *ConnectedEndpoint) Release() { // CloseUnread implements transport.ConnectedEndpoint.CloseUnread. func (c *ConnectedEndpoint) CloseUnread() {} + +// LINT.ThenChange(../../fsimpl/host/socket.go) diff --git a/pkg/sentry/fs/host/socket_iovec.go b/pkg/sentry/fs/host/socket_iovec.go index af6955675..5c18dbd5e 100644 --- a/pkg/sentry/fs/host/socket_iovec.go +++ b/pkg/sentry/fs/host/socket_iovec.go @@ -21,6 +21,8 @@ import ( "gvisor.dev/gvisor/pkg/syserror" ) +// LINT.IfChange + // maxIovs is the maximum number of iovecs to pass to the host. var maxIovs = linux.UIO_MAXIOV @@ -111,3 +113,5 @@ func buildIovec(bufs [][]byte, maxlen int64, truncate bool) (length int64, iovec return total, iovecs, nil, err } + +// LINT.ThenChange(../../fsimpl/host/socket_iovec.go) diff --git a/pkg/sentry/fs/host/socket_unsafe.go b/pkg/sentry/fs/host/socket_unsafe.go index f3bbed7ea..5d4f312cf 100644 --- a/pkg/sentry/fs/host/socket_unsafe.go +++ b/pkg/sentry/fs/host/socket_unsafe.go @@ -19,6 +19,8 @@ import ( "unsafe" ) +// LINT.IfChange + // fdReadVec receives from fd to bufs. // // If the total length of bufs is > maxlen, fdReadVec will do a partial read @@ -99,3 +101,5 @@ func fdWriteVec(fd int, bufs [][]byte, maxlen int64, truncate bool) (int64, int6 return int64(n), length, err } + +// LINT.ThenChange(../../fsimpl/host/socket_unsafe.go) diff --git a/pkg/sentry/fsimpl/host/BUILD b/pkg/sentry/fsimpl/host/BUILD index 2dcb03a73..e1c56d89b 100644 --- a/pkg/sentry/fsimpl/host/BUILD +++ b/pkg/sentry/fsimpl/host/BUILD @@ -8,6 +8,9 @@ go_library( "control.go", "host.go", "ioctl_unsafe.go", + "socket.go", + "socket_iovec.go", + "socket_unsafe.go", "tty.go", "util.go", "util_unsafe.go", @@ -16,6 +19,7 @@ go_library( deps = [ "//pkg/abi/linux", "//pkg/context", + "//pkg/fdnotifier", "//pkg/log", "//pkg/refs", "//pkg/sentry/arch", @@ -25,12 +29,18 @@ go_library( "//pkg/sentry/kernel/auth", "//pkg/sentry/memmap", "//pkg/sentry/socket/control", + "//pkg/sentry/socket/unix", "//pkg/sentry/socket/unix/transport", "//pkg/sentry/unimpl", + "//pkg/sentry/uniqueid", "//pkg/sentry/vfs", "//pkg/sync", + "//pkg/syserr", "//pkg/syserror", + "//pkg/tcpip", + "//pkg/unet", "//pkg/usermem", + "//pkg/waiter", "@org_golang_x_sys//unix:go_default_library", ], ) diff --git a/pkg/sentry/fsimpl/host/host.go b/pkg/sentry/fsimpl/host/host.go index 1e53b5c1b..05538ea42 100644 --- a/pkg/sentry/fsimpl/host/host.go +++ b/pkg/sentry/fsimpl/host/host.go @@ -17,7 +17,6 @@ package host import ( - "errors" "fmt" "math" "syscall" @@ -31,6 +30,7 @@ import ( "gvisor.dev/gvisor/pkg/sentry/hostfd" "gvisor.dev/gvisor/pkg/sentry/kernel/auth" "gvisor.dev/gvisor/pkg/sentry/memmap" + unixsocket "gvisor.dev/gvisor/pkg/sentry/socket/unix" "gvisor.dev/gvisor/pkg/sentry/vfs" "gvisor.dev/gvisor/pkg/sync" "gvisor.dev/gvisor/pkg/syserror" @@ -156,7 +156,7 @@ type inode struct { // Note that these flags may become out of date, since they can be modified // on the host, e.g. with fcntl. -func fileFlagsFromHostFD(fd int) (int, error) { +func fileFlagsFromHostFD(fd int) (uint32, error) { flags, err := unix.FcntlInt(uintptr(fd), syscall.F_GETFL, 0) if err != nil { log.Warningf("Failed to get file flags for donated FD %d: %v", fd, err) @@ -164,7 +164,7 @@ func fileFlagsFromHostFD(fd int) (int, error) { } // TODO(gvisor.dev/issue/1672): implement behavior corresponding to these allowed flags. flags &= syscall.O_ACCMODE | syscall.O_DIRECT | syscall.O_NONBLOCK | syscall.O_DSYNC | syscall.O_SYNC | syscall.O_APPEND - return flags, nil + return uint32(flags), nil } // CheckPermissions implements kernfs.Inode. @@ -361,6 +361,10 @@ func (i *inode) Destroy() { // Open implements kernfs.Inode. func (i *inode) Open(ctx context.Context, rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) { + // Once created, we cannot re-open a socket fd through /proc/[pid]/fd/. + if i.Mode().FileType() == linux.S_IFSOCK { + return nil, syserror.ENXIO + } return i.open(ctx, vfsd, rp.Mount()) } @@ -370,42 +374,45 @@ func (i *inode) open(ctx context.Context, d *vfs.Dentry, mnt *vfs.Mount) (*vfs.F return nil, err } fileType := s.Mode & linux.FileTypeMask + flags, err := fileFlagsFromHostFD(i.hostFD) + if err != nil { + return nil, err + } + if fileType == syscall.S_IFSOCK { if i.isTTY { - return nil, errors.New("cannot use host socket as TTY") + log.Warningf("cannot use host socket fd %d as TTY", i.hostFD) + return nil, syserror.ENOTTY } - // TODO(gvisor.dev/issue/1672): support importing sockets. - return nil, errors.New("importing host sockets not supported") + + ep, err := newEndpoint(ctx, i.hostFD) + if err != nil { + return nil, err + } + // Currently, we only allow Unix sockets to be imported. + return unixsocket.NewFileDescription(ep, ep.Type(), flags, mnt, d) } // TODO(gvisor.dev/issue/1672): Whitelist specific file types here, so that // we don't allow importing arbitrary file types without proper support. - var ( - vfsfd *vfs.FileDescription - fdImpl vfs.FileDescriptionImpl - ) if i.isTTY { fd := &ttyFD{ fileDescription: fileDescription{inode: i}, termios: linux.DefaultSlaveTermios, } - vfsfd = &fd.vfsfd - fdImpl = fd - } else { - // For simplicity, set offset to 0. Technically, we should - // only set to 0 on files that are not seekable (sockets, pipes, etc.), - // and use the offset from the host fd otherwise. - fd := &fileDescription{inode: i} - vfsfd = &fd.vfsfd - fdImpl = fd - } - - flags, err := fileFlagsFromHostFD(i.hostFD) - if err != nil { - return nil, err + vfsfd := &fd.vfsfd + if err := vfsfd.Init(fd, flags, mnt, d, &vfs.FileDescriptionOptions{}); err != nil { + return nil, err + } + return vfsfd, nil } - if err := vfsfd.Init(fdImpl, uint32(flags), mnt, d, &vfs.FileDescriptionOptions{}); err != nil { + // For simplicity, set offset to 0. Technically, we should + // only set to 0 on files that are not seekable (sockets, pipes, etc.), + // and use the offset from the host fd otherwise. + fd := &fileDescription{inode: i} + vfsfd := &fd.vfsfd + if err := vfsfd.Init(fd, flags, mnt, d, &vfs.FileDescriptionOptions{}); err != nil { return nil, err } return vfsfd, nil diff --git a/pkg/sentry/fsimpl/host/socket.go b/pkg/sentry/fsimpl/host/socket.go new file mode 100644 index 000000000..39dd624a0 --- /dev/null +++ b/pkg/sentry/fsimpl/host/socket.go @@ -0,0 +1,397 @@ +// 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 host + +import ( + "fmt" + "syscall" + + "gvisor.dev/gvisor/pkg/abi/linux" + "gvisor.dev/gvisor/pkg/context" + "gvisor.dev/gvisor/pkg/fdnotifier" + "gvisor.dev/gvisor/pkg/log" + "gvisor.dev/gvisor/pkg/refs" + "gvisor.dev/gvisor/pkg/sentry/socket/control" + "gvisor.dev/gvisor/pkg/sentry/socket/unix/transport" + "gvisor.dev/gvisor/pkg/sentry/uniqueid" + "gvisor.dev/gvisor/pkg/sync" + "gvisor.dev/gvisor/pkg/syserr" + "gvisor.dev/gvisor/pkg/syserror" + "gvisor.dev/gvisor/pkg/tcpip" + "gvisor.dev/gvisor/pkg/unet" + "gvisor.dev/gvisor/pkg/waiter" +) + +// Create a new host-backed endpoint from the given fd. +func newEndpoint(ctx context.Context, hostFD int) (transport.Endpoint, error) { + // Set up an external transport.Endpoint using the host fd. + addr := fmt.Sprintf("hostfd:[%d]", hostFD) + var q waiter.Queue + e, err := NewConnectedEndpoint(ctx, hostFD, &q, addr, true /* saveable */) + if err != nil { + return nil, err.ToError() + } + e.Init() + ep := transport.NewExternal(ctx, e.stype, uniqueid.GlobalProviderFromContext(ctx), &q, e, e) + return ep, nil +} + +// maxSendBufferSize is the maximum host send buffer size allowed for endpoint. +// +// N.B. 8MB is the default maximum on Linux (2 * sysctl_wmem_max). +const maxSendBufferSize = 8 << 20 + +// ConnectedEndpoint is an implementation of transport.ConnectedEndpoint and +// transport.Receiver. It is backed by a host fd that was imported at sentry +// startup. This fd is shared with a hostfs inode, which retains ownership of +// it. +// +// ConnectedEndpoint is saveable, since we expect that the host will provide +// the same fd upon restore. +// +// As of this writing, we only allow Unix sockets to be imported. +// +// +stateify savable +type ConnectedEndpoint struct { + // ref keeps track of references to a ConnectedEndpoint. + ref refs.AtomicRefCount + + // mu protects fd below. + mu sync.RWMutex `state:"nosave"` + + // fd is the host fd backing this endpoint. + fd int + + // addr is the address at which this endpoint is bound. + addr string + + queue *waiter.Queue + + // sndbuf is the size of the send buffer. + // + // N.B. When this is smaller than the host size, we present it via + // GetSockOpt and message splitting/rejection in SendMsg, but do not + // prevent lots of small messages from filling the real send buffer + // size on the host. + sndbuf int64 `state:"nosave"` + + // stype is the type of Unix socket. + stype linux.SockType +} + +// init performs initialization required for creating new ConnectedEndpoints and +// for restoring them. +func (c *ConnectedEndpoint) init() *syserr.Error { + family, err := syscall.GetsockoptInt(c.fd, syscall.SOL_SOCKET, syscall.SO_DOMAIN) + if err != nil { + return syserr.FromError(err) + } + + if family != syscall.AF_UNIX { + // We only allow Unix sockets. + return syserr.ErrInvalidEndpointState + } + + stype, err := syscall.GetsockoptInt(c.fd, syscall.SOL_SOCKET, syscall.SO_TYPE) + if err != nil { + return syserr.FromError(err) + } + + if err := syscall.SetNonblock(c.fd, true); err != nil { + return syserr.FromError(err) + } + + sndbuf, err := syscall.GetsockoptInt(c.fd, syscall.SOL_SOCKET, syscall.SO_SNDBUF) + if err != nil { + return syserr.FromError(err) + } + if sndbuf > maxSendBufferSize { + log.Warningf("Socket send buffer too large: %d", sndbuf) + return syserr.ErrInvalidEndpointState + } + + c.stype = linux.SockType(stype) + c.sndbuf = int64(sndbuf) + + return nil +} + +// NewConnectedEndpoint creates a new ConnectedEndpoint backed by a host fd +// imported at sentry startup, +// +// The caller is responsible for calling Init(). Additionaly, Release needs to +// be called twice because ConnectedEndpoint is both a transport.Receiver and +// transport.ConnectedEndpoint. +func NewConnectedEndpoint(ctx context.Context, hostFD int, queue *waiter.Queue, addr string, saveable bool) (*ConnectedEndpoint, *syserr.Error) { + e := ConnectedEndpoint{ + fd: hostFD, + addr: addr, + queue: queue, + } + + if err := e.init(); err != nil { + return nil, err + } + + // AtomicRefCounters start off with a single reference. We need two. + e.ref.IncRef() + e.ref.EnableLeakCheck("host.ConnectedEndpoint") + return &e, nil +} + +// Init will do the initialization required without holding other locks. +func (c *ConnectedEndpoint) Init() { + if err := fdnotifier.AddFD(int32(c.fd), c.queue); err != nil { + panic(err) + } +} + +// Send implements transport.ConnectedEndpoint.Send. +func (c *ConnectedEndpoint) Send(data [][]byte, controlMessages transport.ControlMessages, from tcpip.FullAddress) (int64, bool, *syserr.Error) { + c.mu.RLock() + defer c.mu.RUnlock() + + if !controlMessages.Empty() { + return 0, false, syserr.ErrInvalidEndpointState + } + + // Since stream sockets don't preserve message boundaries, we can write + // only as much of the message as fits in the send buffer. + truncate := c.stype == linux.SOCK_STREAM + + n, totalLen, err := fdWriteVec(c.fd, data, c.sndbuf, truncate) + if n < totalLen && err == nil { + // The host only returns a short write if it would otherwise + // block (and only for stream sockets). + err = syserror.EAGAIN + } + if n > 0 && err != syserror.EAGAIN { + // The caller may need to block to send more data, but + // otherwise there isn't anything that can be done about an + // error with a partial write. + err = nil + } + + // There is no need for the callee to call SendNotify because fdWriteVec + // uses the host's sendmsg(2) and the host kernel's queue. + return n, false, syserr.FromError(err) +} + +// SendNotify implements transport.ConnectedEndpoint.SendNotify. +func (c *ConnectedEndpoint) SendNotify() {} + +// CloseSend implements transport.ConnectedEndpoint.CloseSend. +func (c *ConnectedEndpoint) CloseSend() { + c.mu.Lock() + defer c.mu.Unlock() + + if err := syscall.Shutdown(c.fd, syscall.SHUT_WR); err != nil { + // A well-formed UDS shutdown can't fail. See + // net/unix/af_unix.c:unix_shutdown. + panic(fmt.Sprintf("failed write shutdown on host socket %+v: %v", c, err)) + } +} + +// CloseNotify implements transport.ConnectedEndpoint.CloseNotify. +func (c *ConnectedEndpoint) CloseNotify() {} + +// Writable implements transport.ConnectedEndpoint.Writable. +func (c *ConnectedEndpoint) Writable() bool { + c.mu.RLock() + defer c.mu.RUnlock() + + return fdnotifier.NonBlockingPoll(int32(c.fd), waiter.EventOut)&waiter.EventOut != 0 +} + +// Passcred implements transport.ConnectedEndpoint.Passcred. +func (c *ConnectedEndpoint) Passcred() bool { + // We don't support credential passing for host sockets. + return false +} + +// GetLocalAddress implements transport.ConnectedEndpoint.GetLocalAddress. +func (c *ConnectedEndpoint) GetLocalAddress() (tcpip.FullAddress, *tcpip.Error) { + return tcpip.FullAddress{Addr: tcpip.Address(c.addr)}, nil +} + +// EventUpdate implements transport.ConnectedEndpoint.EventUpdate. +func (c *ConnectedEndpoint) EventUpdate() { + c.mu.RLock() + defer c.mu.RUnlock() + if c.fd != -1 { + fdnotifier.UpdateFD(int32(c.fd)) + } +} + +// Recv implements transport.Receiver.Recv. +func (c *ConnectedEndpoint) Recv(data [][]byte, creds bool, numRights int, peek bool) (int64, int64, transport.ControlMessages, bool, tcpip.FullAddress, bool, *syserr.Error) { + c.mu.RLock() + defer c.mu.RUnlock() + + var cm unet.ControlMessage + if numRights > 0 { + cm.EnableFDs(int(numRights)) + } + + // N.B. Unix sockets don't have a receive buffer, the send buffer + // serves both purposes. + rl, ml, cl, cTrunc, err := fdReadVec(c.fd, data, []byte(cm), peek, c.sndbuf) + if rl > 0 && err != nil { + // We got some data, so all we need to do on error is return + // the data that we got. Short reads are fine, no need to + // block. + err = nil + } + if err != nil { + return 0, 0, transport.ControlMessages{}, false, tcpip.FullAddress{}, false, syserr.FromError(err) + } + + // There is no need for the callee to call RecvNotify because fdReadVec uses + // the host's recvmsg(2) and the host kernel's queue. + + // Trim the control data if we received less than the full amount. + if cl < uint64(len(cm)) { + cm = cm[:cl] + } + + // Avoid extra allocations in the case where there isn't any control data. + if len(cm) == 0 { + return rl, ml, transport.ControlMessages{}, cTrunc, tcpip.FullAddress{Addr: tcpip.Address(c.addr)}, false, nil + } + + fds, err := cm.ExtractFDs() + if err != nil { + return 0, 0, transport.ControlMessages{}, false, tcpip.FullAddress{}, false, syserr.FromError(err) + } + + if len(fds) == 0 { + return rl, ml, transport.ControlMessages{}, cTrunc, tcpip.FullAddress{Addr: tcpip.Address(c.addr)}, false, nil + } + return rl, ml, control.NewVFS2(nil, nil, newSCMRights(fds)), cTrunc, tcpip.FullAddress{Addr: tcpip.Address(c.addr)}, false, nil +} + +// RecvNotify implements transport.Receiver.RecvNotify. +func (c *ConnectedEndpoint) RecvNotify() {} + +// CloseRecv implements transport.Receiver.CloseRecv. +func (c *ConnectedEndpoint) CloseRecv() { + c.mu.Lock() + defer c.mu.Unlock() + + if err := syscall.Shutdown(c.fd, syscall.SHUT_RD); err != nil { + // A well-formed UDS shutdown can't fail. See + // net/unix/af_unix.c:unix_shutdown. + panic(fmt.Sprintf("failed read shutdown on host socket %+v: %v", c, err)) + } +} + +// Readable implements transport.Receiver.Readable. +func (c *ConnectedEndpoint) Readable() bool { + c.mu.RLock() + defer c.mu.RUnlock() + + return fdnotifier.NonBlockingPoll(int32(c.fd), waiter.EventIn)&waiter.EventIn != 0 +} + +// SendQueuedSize implements transport.Receiver.SendQueuedSize. +func (c *ConnectedEndpoint) SendQueuedSize() int64 { + // TODO(gvisor.dev/issue/273): SendQueuedSize isn't supported for host + // sockets because we don't allow the sentry to call ioctl(2). + return -1 +} + +// RecvQueuedSize implements transport.Receiver.RecvQueuedSize. +func (c *ConnectedEndpoint) RecvQueuedSize() int64 { + // TODO(gvisor.dev/issue/273): RecvQueuedSize isn't supported for host + // sockets because we don't allow the sentry to call ioctl(2). + return -1 +} + +// SendMaxQueueSize implements transport.Receiver.SendMaxQueueSize. +func (c *ConnectedEndpoint) SendMaxQueueSize() int64 { + return int64(c.sndbuf) +} + +// RecvMaxQueueSize implements transport.Receiver.RecvMaxQueueSize. +func (c *ConnectedEndpoint) RecvMaxQueueSize() int64 { + // N.B. Unix sockets don't use the receive buffer. We'll claim it is + // the same size as the send buffer. + return int64(c.sndbuf) +} + +func (c *ConnectedEndpoint) destroyLocked() { + fdnotifier.RemoveFD(int32(c.fd)) + c.fd = -1 +} + +// Release implements transport.ConnectedEndpoint.Release and +// transport.Receiver.Release. +func (c *ConnectedEndpoint) Release() { + c.ref.DecRefWithDestructor(func() { + c.mu.Lock() + c.destroyLocked() + c.mu.Unlock() + }) +} + +// CloseUnread implements transport.ConnectedEndpoint.CloseUnread. +func (c *ConnectedEndpoint) CloseUnread() {} + +// SCMConnectedEndpoint represents an endpoint backed by a host fd that was +// passed through a gofer Unix socket. It is almost the same as +// ConnectedEndpoint, with the following differences: +// - SCMConnectedEndpoint is not saveable, because the host cannot guarantee +// the same descriptor number across S/R. +// - SCMConnectedEndpoint holds ownership of its fd and is responsible for +// closing it. +type SCMConnectedEndpoint struct { + ConnectedEndpoint +} + +// Release implements transport.ConnectedEndpoint.Release and +// transport.Receiver.Release. +func (e *SCMConnectedEndpoint) Release() { + e.ref.DecRefWithDestructor(func() { + e.mu.Lock() + if err := syscall.Close(e.fd); err != nil { + log.Warningf("Failed to close host fd %d: %v", err) + } + e.destroyLocked() + e.mu.Unlock() + }) +} + +// NewSCMEndpoint creates a new SCMConnectedEndpoint backed by a host fd that +// was passed through a Unix socket. +// +// The caller is responsible for calling Init(). Additionaly, Release needs to +// be called twice because ConnectedEndpoint is both a transport.Receiver and +// transport.ConnectedEndpoint. +func NewSCMEndpoint(ctx context.Context, hostFD int, queue *waiter.Queue, addr string) (*SCMConnectedEndpoint, *syserr.Error) { + e := SCMConnectedEndpoint{ConnectedEndpoint{ + fd: hostFD, + addr: addr, + queue: queue, + }} + + if err := e.init(); err != nil { + return nil, err + } + + // AtomicRefCounters start off with a single reference. We need two. + e.ref.IncRef() + e.ref.EnableLeakCheck("host.SCMConnectedEndpoint") + return &e, nil +} diff --git a/pkg/sentry/fsimpl/host/socket_iovec.go b/pkg/sentry/fsimpl/host/socket_iovec.go new file mode 100644 index 000000000..584c247d2 --- /dev/null +++ b/pkg/sentry/fsimpl/host/socket_iovec.go @@ -0,0 +1,113 @@ +// 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 host + +import ( + "syscall" + + "gvisor.dev/gvisor/pkg/abi/linux" + "gvisor.dev/gvisor/pkg/syserror" +) + +// maxIovs is the maximum number of iovecs to pass to the host. +var maxIovs = linux.UIO_MAXIOV + +// copyToMulti copies as many bytes from src to dst as possible. +func copyToMulti(dst [][]byte, src []byte) { + for _, d := range dst { + done := copy(d, src) + src = src[done:] + if len(src) == 0 { + break + } + } +} + +// copyFromMulti copies as many bytes from src to dst as possible. +func copyFromMulti(dst []byte, src [][]byte) { + for _, s := range src { + done := copy(dst, s) + dst = dst[done:] + if len(dst) == 0 { + break + } + } +} + +// buildIovec builds an iovec slice from the given []byte slice. +// +// If truncate, truncate bufs > maxlen. Otherwise, immediately return an error. +// +// If length < the total length of bufs, err indicates why, even when returning +// a truncated iovec. +// +// If intermediate != nil, iovecs references intermediate rather than bufs and +// the caller must copy to/from bufs as necessary. +func buildIovec(bufs [][]byte, maxlen int64, truncate bool) (length int64, iovecs []syscall.Iovec, intermediate []byte, err error) { + var iovsRequired int + for _, b := range bufs { + length += int64(len(b)) + if len(b) > 0 { + iovsRequired++ + } + } + + stopLen := length + if length > maxlen { + if truncate { + stopLen = maxlen + err = syserror.EAGAIN + } else { + return 0, nil, nil, syserror.EMSGSIZE + } + } + + if iovsRequired > maxIovs { + // The kernel will reject our call if we pass this many iovs. + // Use a single intermediate buffer instead. + b := make([]byte, stopLen) + + return stopLen, []syscall.Iovec{{ + Base: &b[0], + Len: uint64(stopLen), + }}, b, err + } + + var total int64 + iovecs = make([]syscall.Iovec, 0, iovsRequired) + for i := range bufs { + l := len(bufs[i]) + if l == 0 { + continue + } + + stop := int64(l) + if total+stop > stopLen { + stop = stopLen - total + } + + iovecs = append(iovecs, syscall.Iovec{ + Base: &bufs[i][0], + Len: uint64(stop), + }) + + total += stop + if total >= stopLen { + break + } + } + + return total, iovecs, nil, err +} diff --git a/pkg/sentry/fsimpl/host/socket_unsafe.go b/pkg/sentry/fsimpl/host/socket_unsafe.go new file mode 100644 index 000000000..35ded24bc --- /dev/null +++ b/pkg/sentry/fsimpl/host/socket_unsafe.go @@ -0,0 +1,101 @@ +// 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 host + +import ( + "syscall" + "unsafe" +) + +// fdReadVec receives from fd to bufs. +// +// If the total length of bufs is > maxlen, fdReadVec will do a partial read +// and err will indicate why the message was truncated. +func fdReadVec(fd int, bufs [][]byte, control []byte, peek bool, maxlen int64) (readLen int64, msgLen int64, controlLen uint64, controlTrunc bool, err error) { + flags := uintptr(syscall.MSG_DONTWAIT | syscall.MSG_TRUNC) + if peek { + flags |= syscall.MSG_PEEK + } + + // Always truncate the receive buffer. All socket types will truncate + // received messages. + length, iovecs, intermediate, err := buildIovec(bufs, maxlen, true) + if err != nil && len(iovecs) == 0 { + // No partial write to do, return error immediately. + return 0, 0, 0, false, err + } + + var msg syscall.Msghdr + if len(control) != 0 { + msg.Control = &control[0] + msg.Controllen = uint64(len(control)) + } + + if len(iovecs) != 0 { + msg.Iov = &iovecs[0] + msg.Iovlen = uint64(len(iovecs)) + } + + rawN, _, e := syscall.RawSyscall(syscall.SYS_RECVMSG, uintptr(fd), uintptr(unsafe.Pointer(&msg)), flags) + if e != 0 { + // N.B. prioritize the syscall error over the buildIovec error. + return 0, 0, 0, false, e + } + n := int64(rawN) + + // Copy data back to bufs. + if intermediate != nil { + copyToMulti(bufs, intermediate) + } + + controlTrunc = msg.Flags&syscall.MSG_CTRUNC == syscall.MSG_CTRUNC + + if n > length { + return length, n, msg.Controllen, controlTrunc, err + } + + return n, n, msg.Controllen, controlTrunc, err +} + +// fdWriteVec sends from bufs to fd. +// +// If the total length of bufs is > maxlen && truncate, fdWriteVec will do a +// partial write and err will indicate why the message was truncated. +func fdWriteVec(fd int, bufs [][]byte, maxlen int64, truncate bool) (int64, int64, error) { + length, iovecs, intermediate, err := buildIovec(bufs, maxlen, truncate) + if err != nil && len(iovecs) == 0 { + // No partial write to do, return error immediately. + return 0, length, err + } + + // Copy data to intermediate buf. + if intermediate != nil { + copyFromMulti(intermediate, bufs) + } + + var msg syscall.Msghdr + if len(iovecs) > 0 { + msg.Iov = &iovecs[0] + msg.Iovlen = uint64(len(iovecs)) + } + + n, _, e := syscall.RawSyscall(syscall.SYS_SENDMSG, uintptr(fd), uintptr(unsafe.Pointer(&msg)), syscall.MSG_DONTWAIT|syscall.MSG_NOSIGNAL) + if e != 0 { + // N.B. prioritize the syscall error over the buildIovec error. + return 0, length, e + } + + return int64(n), length, err +} diff --git a/pkg/sentry/fsimpl/sockfs/sockfs.go b/pkg/sentry/fsimpl/sockfs/sockfs.go index 5ce50625b..271134af8 100644 --- a/pkg/sentry/fsimpl/sockfs/sockfs.go +++ b/pkg/sentry/fsimpl/sockfs/sockfs.go @@ -73,26 +73,14 @@ func (i *inode) Open(ctx context.Context, rp *vfs.ResolvingPath, vfsd *vfs.Dentr return nil, syserror.ENXIO } -// InitSocket initializes a socket FileDescription, with a corresponding -// Dentry in mnt. -// -// fd should be the FileDescription associated with socketImpl, i.e. its first -// field. mnt should be the global socket mount, Kernel.socketMount. -func InitSocket(socketImpl vfs.FileDescriptionImpl, fd *vfs.FileDescription, mnt *vfs.Mount, creds *auth.Credentials) error { - fsimpl := mnt.Filesystem().Impl() - fs := fsimpl.(*kernfs.Filesystem) - +// NewDentry constructs and returns a sockfs dentry. +func NewDentry(creds *auth.Credentials, ino uint64) *vfs.Dentry { // File mode matches net/socket.c:sock_alloc. filemode := linux.FileMode(linux.S_IFSOCK | 0600) i := &inode{} - i.Init(creds, fs.NextIno(), filemode) + i.Init(creds, ino, filemode) d := &kernfs.Dentry{} d.Init(i) - - opts := &vfs.FileDescriptionOptions{UseDentryMetadata: true} - if err := fd.Init(socketImpl, linux.O_RDWR, mnt, d.VFSDentry(), opts); err != nil { - return err - } - return nil + return d.VFSDentry() } diff --git a/pkg/sentry/socket/unix/BUILD b/pkg/sentry/socket/unix/BUILD index de2cc4bdf..941a91097 100644 --- a/pkg/sentry/socket/unix/BUILD +++ b/pkg/sentry/socket/unix/BUILD @@ -21,6 +21,7 @@ go_library( "//pkg/sentry/device", "//pkg/sentry/fs", "//pkg/sentry/fs/fsutil", + "//pkg/sentry/fsimpl/kernfs", "//pkg/sentry/fsimpl/sockfs", "//pkg/sentry/kernel", "//pkg/sentry/kernel/time", diff --git a/pkg/sentry/socket/unix/unix_vfs2.go b/pkg/sentry/socket/unix/unix_vfs2.go index 3e54d49c4..315dc274f 100644 --- a/pkg/sentry/socket/unix/unix_vfs2.go +++ b/pkg/sentry/socket/unix/unix_vfs2.go @@ -19,6 +19,7 @@ import ( "gvisor.dev/gvisor/pkg/context" "gvisor.dev/gvisor/pkg/fspath" "gvisor.dev/gvisor/pkg/sentry/arch" + "gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs" "gvisor.dev/gvisor/pkg/sentry/fsimpl/sockfs" "gvisor.dev/gvisor/pkg/sentry/kernel" "gvisor.dev/gvisor/pkg/sentry/socket/control" @@ -42,30 +43,44 @@ type SocketVFS2 struct { socketOpsCommon } -// NewVFS2File creates and returns a new vfs.FileDescription for a unix socket. -func NewVFS2File(t *kernel.Task, ep transport.Endpoint, stype linux.SockType) (*vfs.FileDescription, *syserr.Error) { - sock := NewFDImpl(ep, stype) - vfsfd := &sock.vfsfd - if err := sockfs.InitSocket(sock, vfsfd, t.Kernel().SocketMount(), t.Credentials()); err != nil { +// NewSockfsFile creates a new socket file in the global sockfs mount and +// returns a corresponding file description. +func NewSockfsFile(t *kernel.Task, ep transport.Endpoint, stype linux.SockType) (*vfs.FileDescription, *syserr.Error) { + mnt := t.Kernel().SocketMount() + fs := mnt.Filesystem().Impl().(*kernfs.Filesystem) + d := sockfs.NewDentry(t.Credentials(), fs.NextIno()) + + fd, err := NewFileDescription(ep, stype, linux.O_RDWR, mnt, d) + if err != nil { return nil, syserr.FromError(err) } - return vfsfd, nil + return fd, nil } -// NewFDImpl creates and returns a new SocketVFS2. -func NewFDImpl(ep transport.Endpoint, stype linux.SockType) *SocketVFS2 { +// NewFileDescription creates and returns a socket file description +// corresponding to the given mount and dentry. +func NewFileDescription(ep transport.Endpoint, stype linux.SockType, flags uint32, mnt *vfs.Mount, d *vfs.Dentry) (*vfs.FileDescription, error) { // You can create AF_UNIX, SOCK_RAW sockets. They're the same as // SOCK_DGRAM and don't require CAP_NET_RAW. if stype == linux.SOCK_RAW { stype = linux.SOCK_DGRAM } - return &SocketVFS2{ + sock := &SocketVFS2{ socketOpsCommon: socketOpsCommon{ ep: ep, stype: stype, }, } + vfsfd := &sock.vfsfd + if err := vfsfd.Init(sock, flags, mnt, d, &vfs.FileDescriptionOptions{ + DenyPRead: true, + DenyPWrite: true, + UseDentryMetadata: true, + }); err != nil { + return nil, err + } + return vfsfd, nil } // GetSockOpt implements the linux syscall getsockopt(2) for sockets backed by @@ -112,8 +127,7 @@ func (s *SocketVFS2) Accept(t *kernel.Task, peerRequested bool, flags int, block } } - // We expect this to be a FileDescription here. - ns, err := NewVFS2File(t, ep, s.stype) + ns, err := NewSockfsFile(t, ep, s.stype) if err != nil { return 0, nil, 0, err } @@ -307,7 +321,7 @@ func (*providerVFS2) Socket(t *kernel.Task, stype linux.SockType, protocol int) return nil, syserr.ErrInvalidArgument } - f, err := NewVFS2File(t, ep, stype) + f, err := NewSockfsFile(t, ep, stype) if err != nil { ep.Close() return nil, err @@ -331,13 +345,13 @@ func (*providerVFS2) Pair(t *kernel.Task, stype linux.SockType, protocol int) (* // Create the endpoints and sockets. ep1, ep2 := transport.NewPair(t, stype, t.Kernel()) - s1, err := NewVFS2File(t, ep1, stype) + s1, err := NewSockfsFile(t, ep1, stype) if err != nil { ep1.Close() ep2.Close() return nil, nil, err } - s2, err := NewVFS2File(t, ep2, stype) + s2, err := NewSockfsFile(t, ep2, stype) if err != nil { s1.DecRef() ep2.Close() |