diff options
Diffstat (limited to 'pkg/sentry/fsimpl/devpts')
| -rw-r--r-- | pkg/sentry/fsimpl/devpts/BUILD | 44 | ||||
| -rw-r--r-- | pkg/sentry/fsimpl/devpts/devpts.go | 233 | ||||
| -rw-r--r-- | pkg/sentry/fsimpl/devpts/devpts_test.go | 56 | ||||
| -rw-r--r-- | pkg/sentry/fsimpl/devpts/line_discipline.go | 445 | ||||
| -rw-r--r-- | pkg/sentry/fsimpl/devpts/master.go | 237 | ||||
| -rw-r--r-- | pkg/sentry/fsimpl/devpts/queue.go | 236 | ||||
| -rw-r--r-- | pkg/sentry/fsimpl/devpts/slave.go | 197 | ||||
| -rw-r--r-- | pkg/sentry/fsimpl/devpts/terminal.go | 120 |
8 files changed, 1568 insertions, 0 deletions
diff --git a/pkg/sentry/fsimpl/devpts/BUILD b/pkg/sentry/fsimpl/devpts/BUILD new file mode 100644 index 000000000..93512c9b6 --- /dev/null +++ b/pkg/sentry/fsimpl/devpts/BUILD @@ -0,0 +1,44 @@ +load("//tools:defs.bzl", "go_library", "go_test") + +licenses(["notice"]) + +go_library( + name = "devpts", + srcs = [ + "devpts.go", + "line_discipline.go", + "master.go", + "queue.go", + "slave.go", + "terminal.go", + ], + visibility = ["//pkg/sentry:internal"], + deps = [ + "//pkg/abi/linux", + "//pkg/context", + "//pkg/safemem", + "//pkg/sentry/arch", + "//pkg/sentry/fs/lock", + "//pkg/sentry/fsimpl/kernfs", + "//pkg/sentry/kernel", + "//pkg/sentry/kernel/auth", + "//pkg/sentry/unimpl", + "//pkg/sentry/vfs", + "//pkg/sync", + "//pkg/syserror", + "//pkg/usermem", + "//pkg/waiter", + ], +) + +go_test( + name = "devpts_test", + size = "small", + srcs = ["devpts_test.go"], + library = ":devpts", + deps = [ + "//pkg/abi/linux", + "//pkg/sentry/contexttest", + "//pkg/usermem", + ], +) diff --git a/pkg/sentry/fsimpl/devpts/devpts.go b/pkg/sentry/fsimpl/devpts/devpts.go new file mode 100644 index 000000000..7169e91af --- /dev/null +++ b/pkg/sentry/fsimpl/devpts/devpts.go @@ -0,0 +1,233 @@ +// 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 devpts provides a filesystem implementation that behaves like +// devpts. +package devpts + +import ( + "fmt" + "math" + "sort" + "strconv" + "sync" + + "gvisor.dev/gvisor/pkg/abi/linux" + "gvisor.dev/gvisor/pkg/context" + "gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs" + "gvisor.dev/gvisor/pkg/sentry/kernel/auth" + "gvisor.dev/gvisor/pkg/sentry/vfs" + "gvisor.dev/gvisor/pkg/syserror" +) + +// Name is the filesystem name. +const Name = "devpts" + +// FilesystemType implements vfs.FilesystemType. +type FilesystemType struct{} + +// Name implements vfs.FilesystemType.Name. +func (FilesystemType) Name() string { + return Name +} + +var _ vfs.FilesystemType = (*FilesystemType)(nil) + +// GetFilesystem implements vfs.FilesystemType.GetFilesystem. +func (fstype FilesystemType) GetFilesystem(ctx context.Context, vfsObj *vfs.VirtualFilesystem, creds *auth.Credentials, source string, opts vfs.GetFilesystemOptions) (*vfs.Filesystem, *vfs.Dentry, error) { + // No data allowed. + if opts.Data != "" { + return nil, nil, syserror.EINVAL + } + + fs, root, err := fstype.newFilesystem(vfsObj, creds) + if err != nil { + return nil, nil, err + } + return fs.Filesystem.VFSFilesystem(), root.VFSDentry(), nil +} + +type filesystem struct { + kernfs.Filesystem + + devMinor uint32 +} + +// newFilesystem creates a new devpts filesystem with root directory and ptmx +// master inode. It returns the filesystem and root Dentry. +func (fstype FilesystemType) newFilesystem(vfsObj *vfs.VirtualFilesystem, creds *auth.Credentials) (*filesystem, *kernfs.Dentry, error) { + devMinor, err := vfsObj.GetAnonBlockDevMinor() + if err != nil { + return nil, nil, err + } + + fs := &filesystem{ + devMinor: devMinor, + } + fs.Filesystem.VFSFilesystem().Init(vfsObj, fstype, fs) + + // Construct the root directory. This is always inode id 1. + root := &rootInode{ + slaves: make(map[uint32]*slaveInode), + } + root.InodeAttrs.Init(creds, linux.UNNAMED_MAJOR, devMinor, 1, linux.ModeDirectory|0555) + root.OrderedChildren.Init(kernfs.OrderedChildrenOptions{}) + root.dentry.Init(root) + + // Construct the pts master inode and dentry. Linux always uses inode + // id 2 for ptmx. See fs/devpts/inode.c:mknod_ptmx. + master := &masterInode{ + root: root, + } + master.InodeAttrs.Init(creds, linux.UNNAMED_MAJOR, devMinor, 2, linux.ModeCharacterDevice|0666) + master.dentry.Init(master) + + // Add the master as a child of the root. + links := root.OrderedChildren.Populate(&root.dentry, map[string]*kernfs.Dentry{ + "ptmx": &master.dentry, + }) + root.IncLinks(links) + + return fs, &root.dentry, nil +} + +// Release implements vfs.FilesystemImpl.Release. +func (fs *filesystem) Release(ctx context.Context) { + fs.Filesystem.VFSFilesystem().VirtualFilesystem().PutAnonBlockDevMinor(fs.devMinor) + fs.Filesystem.Release(ctx) +} + +// rootInode is the root directory inode for the devpts mounts. +type rootInode struct { + kernfs.AlwaysValid + kernfs.InodeAttrs + kernfs.InodeDirectoryNoNewChildren + kernfs.InodeNotSymlink + kernfs.OrderedChildren + + locks vfs.FileLocks + + // Keep a reference to this inode's dentry. + dentry kernfs.Dentry + + // master is the master pty inode. Immutable. + master *masterInode + + // root is the root directory inode for this filesystem. Immutable. + root *rootInode + + // mu protects the fields below. + mu sync.Mutex + + // slaves maps pty ids to slave inodes. + slaves map[uint32]*slaveInode + + // nextIdx is the next pty index to use. Must be accessed atomically. + // + // TODO(b/29356795): reuse indices when ptys are closed. + nextIdx uint32 +} + +var _ kernfs.Inode = (*rootInode)(nil) + +// allocateTerminal creates a new Terminal and installs a pts node for it. +func (i *rootInode) allocateTerminal(creds *auth.Credentials) (*Terminal, error) { + i.mu.Lock() + defer i.mu.Unlock() + if i.nextIdx == math.MaxUint32 { + return nil, syserror.ENOMEM + } + idx := i.nextIdx + i.nextIdx++ + + // Sanity check that slave with idx does not exist. + if _, ok := i.slaves[idx]; ok { + panic(fmt.Sprintf("pty index collision; index %d already exists", idx)) + } + + // Create the new terminal and slave. + t := newTerminal(idx) + slave := &slaveInode{ + root: i, + t: t, + } + // Linux always uses pty index + 3 as the inode id. See + // fs/devpts/inode.c:devpts_pty_new(). + slave.InodeAttrs.Init(creds, i.InodeAttrs.DevMajor(), i.InodeAttrs.DevMinor(), uint64(idx+3), linux.ModeCharacterDevice|0600) + slave.dentry.Init(slave) + i.slaves[idx] = slave + + return t, nil +} + +// masterClose is called when the master end of t is closed. +func (i *rootInode) masterClose(t *Terminal) { + i.mu.Lock() + defer i.mu.Unlock() + + // Sanity check that slave with idx exists. + if _, ok := i.slaves[t.n]; !ok { + panic(fmt.Sprintf("pty with index %d does not exist", t.n)) + } + delete(i.slaves, t.n) +} + +// Open implements kernfs.Inode.Open. +func (i *rootInode) Open(ctx context.Context, rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) { + fd, err := kernfs.NewGenericDirectoryFD(rp.Mount(), vfsd, &i.OrderedChildren, &i.locks, &opts) + if err != nil { + return nil, err + } + return fd.VFSFileDescription(), nil +} + +// Lookup implements kernfs.Inode.Lookup. +func (i *rootInode) Lookup(ctx context.Context, name string) (*vfs.Dentry, error) { + idx, err := strconv.ParseUint(name, 10, 32) + if err != nil { + return nil, syserror.ENOENT + } + i.mu.Lock() + defer i.mu.Unlock() + if si, ok := i.slaves[uint32(idx)]; ok { + si.dentry.IncRef() + return si.dentry.VFSDentry(), nil + + } + return nil, syserror.ENOENT +} + +// IterDirents implements kernfs.Inode.IterDirents. +func (i *rootInode) IterDirents(ctx context.Context, cb vfs.IterDirentsCallback, offset, relOffset int64) (int64, error) { + i.mu.Lock() + defer i.mu.Unlock() + ids := make([]int, 0, len(i.slaves)) + for id := range i.slaves { + ids = append(ids, int(id)) + } + sort.Ints(ids) + for _, id := range ids[relOffset:] { + dirent := vfs.Dirent{ + Name: strconv.FormatUint(uint64(id), 10), + Type: linux.DT_CHR, + Ino: i.slaves[uint32(id)].InodeAttrs.Ino(), + NextOff: offset + 1, + } + if err := cb.Handle(dirent); err != nil { + return offset, err + } + offset++ + } + return offset, nil +} diff --git a/pkg/sentry/fsimpl/devpts/devpts_test.go b/pkg/sentry/fsimpl/devpts/devpts_test.go new file mode 100644 index 000000000..b7c149047 --- /dev/null +++ b/pkg/sentry/fsimpl/devpts/devpts_test.go @@ -0,0 +1,56 @@ +// Copyright 2018 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package devpts + +import ( + "testing" + + "gvisor.dev/gvisor/pkg/abi/linux" + "gvisor.dev/gvisor/pkg/sentry/contexttest" + "gvisor.dev/gvisor/pkg/usermem" +) + +func TestSimpleMasterToSlave(t *testing.T) { + ld := newLineDiscipline(linux.DefaultSlaveTermios) + ctx := contexttest.Context(t) + inBytes := []byte("hello, tty\n") + src := usermem.BytesIOSequence(inBytes) + outBytes := make([]byte, 32) + dst := usermem.BytesIOSequence(outBytes) + + // Write to the input queue. + nw, err := ld.inputQueueWrite(ctx, src) + if err != nil { + t.Fatalf("error writing to input queue: %v", err) + } + if nw != int64(len(inBytes)) { + t.Fatalf("wrote wrong length: got %d, want %d", nw, len(inBytes)) + } + + // Read from the input queue. + nr, err := ld.inputQueueRead(ctx, dst) + if err != nil { + t.Fatalf("error reading from input queue: %v", err) + } + if nr != int64(len(inBytes)) { + t.Fatalf("read wrong length: got %d, want %d", nr, len(inBytes)) + } + + outStr := string(outBytes[:nr]) + inStr := string(inBytes) + if outStr != inStr { + t.Fatalf("written and read strings do not match: got %q, want %q", outStr, inStr) + } +} diff --git a/pkg/sentry/fsimpl/devpts/line_discipline.go b/pkg/sentry/fsimpl/devpts/line_discipline.go new file mode 100644 index 000000000..f7bc325d1 --- /dev/null +++ b/pkg/sentry/fsimpl/devpts/line_discipline.go @@ -0,0 +1,445 @@ +// Copyright 2018 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package devpts + +import ( + "bytes" + "unicode/utf8" + + "gvisor.dev/gvisor/pkg/abi/linux" + "gvisor.dev/gvisor/pkg/context" + "gvisor.dev/gvisor/pkg/sentry/arch" + "gvisor.dev/gvisor/pkg/sync" + "gvisor.dev/gvisor/pkg/syserror" + "gvisor.dev/gvisor/pkg/usermem" + "gvisor.dev/gvisor/pkg/waiter" +) + +const ( + // canonMaxBytes is the number of bytes that fit into a single line of + // terminal input in canonical mode. This corresponds to N_TTY_BUF_SIZE + // in include/linux/tty.h. + canonMaxBytes = 4096 + + // nonCanonMaxBytes is the maximum number of bytes that can be read at + // a time in noncanonical mode. + nonCanonMaxBytes = canonMaxBytes - 1 + + spacesPerTab = 8 +) + +// lineDiscipline dictates how input and output are handled between the +// pseudoterminal (pty) master and slave. It can be configured to alter I/O, +// modify control characters (e.g. Ctrl-C for SIGINT), etc. The following man +// pages are good resources for how to affect the line discipline: +// +// * termios(3) +// * tty_ioctl(4) +// +// This file corresponds most closely to drivers/tty/n_tty.c. +// +// lineDiscipline has a simple structure but supports a multitude of options +// (see the above man pages). It consists of two queues of bytes: one from the +// terminal master to slave (the input queue) and one from slave to master (the +// output queue). When bytes are written to one end of the pty, the line +// discipline reads the bytes, modifies them or takes special action if +// required, and enqueues them to be read by the other end of the pty: +// +// input from terminal +-------------+ input to process (e.g. bash) +// +------------------------>| input queue |---------------------------+ +// | (inputQueueWrite) +-------------+ (inputQueueRead) | +// | | +// | v +// masterFD slaveFD +// ^ | +// | | +// | output to terminal +--------------+ output from process | +// +------------------------| output queue |<--------------------------+ +// (outputQueueRead) +--------------+ (outputQueueWrite) +// +// Lock order: +// termiosMu +// inQueue.mu +// outQueue.mu +// +// +stateify savable +type lineDiscipline struct { + // sizeMu protects size. + sizeMu sync.Mutex `state:"nosave"` + + // size is the terminal size (width and height). + size linux.WindowSize + + // inQueue is the input queue of the terminal. + inQueue queue + + // outQueue is the output queue of the terminal. + outQueue queue + + // termiosMu protects termios. + termiosMu sync.RWMutex `state:"nosave"` + + // termios is the terminal configuration used by the lineDiscipline. + termios linux.KernelTermios + + // column is the location in a row of the cursor. This is important for + // handling certain special characters like backspace. + column int + + // masterWaiter is used to wait on the master end of the TTY. + masterWaiter waiter.Queue `state:"zerovalue"` + + // slaveWaiter is used to wait on the slave end of the TTY. + slaveWaiter waiter.Queue `state:"zerovalue"` +} + +func newLineDiscipline(termios linux.KernelTermios) *lineDiscipline { + ld := lineDiscipline{termios: termios} + ld.inQueue.transformer = &inputQueueTransformer{} + ld.outQueue.transformer = &outputQueueTransformer{} + return &ld +} + +// getTermios gets the linux.Termios for the tty. +func (l *lineDiscipline) getTermios(ctx context.Context, io usermem.IO, args arch.SyscallArguments) (uintptr, error) { + l.termiosMu.RLock() + defer l.termiosMu.RUnlock() + // We must copy a Termios struct, not KernelTermios. + t := l.termios.ToTermios() + _, err := usermem.CopyObjectOut(ctx, io, args[2].Pointer(), t, usermem.IOOpts{ + AddressSpaceActive: true, + }) + return 0, err +} + +// setTermios sets a linux.Termios for the tty. +func (l *lineDiscipline) setTermios(ctx context.Context, io usermem.IO, args arch.SyscallArguments) (uintptr, error) { + l.termiosMu.Lock() + defer l.termiosMu.Unlock() + oldCanonEnabled := l.termios.LEnabled(linux.ICANON) + // We must copy a Termios struct, not KernelTermios. + var t linux.Termios + _, err := usermem.CopyObjectIn(ctx, io, args[2].Pointer(), &t, usermem.IOOpts{ + AddressSpaceActive: true, + }) + l.termios.FromTermios(t) + + // If canonical mode is turned off, move bytes from inQueue's wait + // buffer to its read buffer. Anything already in the read buffer is + // now readable. + if oldCanonEnabled && !l.termios.LEnabled(linux.ICANON) { + l.inQueue.mu.Lock() + l.inQueue.pushWaitBufLocked(l) + l.inQueue.readable = true + l.inQueue.mu.Unlock() + l.slaveWaiter.Notify(waiter.EventIn) + } + + return 0, err +} + +func (l *lineDiscipline) windowSize(ctx context.Context, io usermem.IO, args arch.SyscallArguments) error { + l.sizeMu.Lock() + defer l.sizeMu.Unlock() + _, err := usermem.CopyObjectOut(ctx, io, args[2].Pointer(), l.size, usermem.IOOpts{ + AddressSpaceActive: true, + }) + return err +} + +func (l *lineDiscipline) setWindowSize(ctx context.Context, io usermem.IO, args arch.SyscallArguments) error { + l.sizeMu.Lock() + defer l.sizeMu.Unlock() + _, err := usermem.CopyObjectIn(ctx, io, args[2].Pointer(), &l.size, usermem.IOOpts{ + AddressSpaceActive: true, + }) + return err +} + +func (l *lineDiscipline) masterReadiness() waiter.EventMask { + // We don't have to lock a termios because the default master termios + // is immutable. + return l.inQueue.writeReadiness(&linux.MasterTermios) | l.outQueue.readReadiness(&linux.MasterTermios) +} + +func (l *lineDiscipline) slaveReadiness() waiter.EventMask { + l.termiosMu.RLock() + defer l.termiosMu.RUnlock() + return l.outQueue.writeReadiness(&l.termios) | l.inQueue.readReadiness(&l.termios) +} + +func (l *lineDiscipline) inputQueueReadSize(ctx context.Context, io usermem.IO, args arch.SyscallArguments) error { + return l.inQueue.readableSize(ctx, io, args) +} + +func (l *lineDiscipline) inputQueueRead(ctx context.Context, dst usermem.IOSequence) (int64, error) { + l.termiosMu.RLock() + defer l.termiosMu.RUnlock() + n, pushed, err := l.inQueue.read(ctx, dst, l) + if err != nil { + return 0, err + } + if n > 0 { + l.masterWaiter.Notify(waiter.EventOut) + if pushed { + l.slaveWaiter.Notify(waiter.EventIn) + } + return n, nil + } + return 0, syserror.ErrWouldBlock +} + +func (l *lineDiscipline) inputQueueWrite(ctx context.Context, src usermem.IOSequence) (int64, error) { + l.termiosMu.RLock() + defer l.termiosMu.RUnlock() + n, err := l.inQueue.write(ctx, src, l) + if err != nil { + return 0, err + } + if n > 0 { + l.slaveWaiter.Notify(waiter.EventIn) + return n, nil + } + return 0, syserror.ErrWouldBlock +} + +func (l *lineDiscipline) outputQueueReadSize(ctx context.Context, io usermem.IO, args arch.SyscallArguments) error { + return l.outQueue.readableSize(ctx, io, args) +} + +func (l *lineDiscipline) outputQueueRead(ctx context.Context, dst usermem.IOSequence) (int64, error) { + l.termiosMu.RLock() + defer l.termiosMu.RUnlock() + n, pushed, err := l.outQueue.read(ctx, dst, l) + if err != nil { + return 0, err + } + if n > 0 { + l.slaveWaiter.Notify(waiter.EventOut) + if pushed { + l.masterWaiter.Notify(waiter.EventIn) + } + return n, nil + } + return 0, syserror.ErrWouldBlock +} + +func (l *lineDiscipline) outputQueueWrite(ctx context.Context, src usermem.IOSequence) (int64, error) { + l.termiosMu.RLock() + defer l.termiosMu.RUnlock() + n, err := l.outQueue.write(ctx, src, l) + if err != nil { + return 0, err + } + if n > 0 { + l.masterWaiter.Notify(waiter.EventIn) + return n, nil + } + return 0, syserror.ErrWouldBlock +} + +// transformer is a helper interface to make it easier to stateify queue. +type transformer interface { + // transform functions require queue's mutex to be held. + transform(*lineDiscipline, *queue, []byte) int +} + +// outputQueueTransformer implements transformer. It performs line discipline +// transformations on the output queue. +// +// +stateify savable +type outputQueueTransformer struct{} + +// transform does output processing for one end of the pty. See +// drivers/tty/n_tty.c:do_output_char for an analogous kernel function. +// +// Preconditions: +// * l.termiosMu must be held for reading. +// * q.mu must be held. +func (*outputQueueTransformer) transform(l *lineDiscipline, q *queue, buf []byte) int { + // transformOutput is effectively always in noncanonical mode, as the + // master termios never has ICANON set. + + if !l.termios.OEnabled(linux.OPOST) { + q.readBuf = append(q.readBuf, buf...) + if len(q.readBuf) > 0 { + q.readable = true + } + return len(buf) + } + + var ret int + for len(buf) > 0 { + size := l.peek(buf) + cBytes := append([]byte{}, buf[:size]...) + ret += size + buf = buf[size:] + // We're guaranteed that cBytes has at least one element. + switch cBytes[0] { + case '\n': + if l.termios.OEnabled(linux.ONLRET) { + l.column = 0 + } + if l.termios.OEnabled(linux.ONLCR) { + q.readBuf = append(q.readBuf, '\r', '\n') + continue + } + case '\r': + if l.termios.OEnabled(linux.ONOCR) && l.column == 0 { + continue + } + if l.termios.OEnabled(linux.OCRNL) { + cBytes[0] = '\n' + if l.termios.OEnabled(linux.ONLRET) { + l.column = 0 + } + break + } + l.column = 0 + case '\t': + spaces := spacesPerTab - l.column%spacesPerTab + if l.termios.OutputFlags&linux.TABDLY == linux.XTABS { + l.column += spaces + q.readBuf = append(q.readBuf, bytes.Repeat([]byte{' '}, spacesPerTab)...) + continue + } + l.column += spaces + case '\b': + if l.column > 0 { + l.column-- + } + default: + l.column++ + } + q.readBuf = append(q.readBuf, cBytes...) + } + if len(q.readBuf) > 0 { + q.readable = true + } + return ret +} + +// inputQueueTransformer implements transformer. It performs line discipline +// transformations on the input queue. +// +// +stateify savable +type inputQueueTransformer struct{} + +// transform does input processing for one end of the pty. Characters read are +// transformed according to flags set in the termios struct. See +// drivers/tty/n_tty.c:n_tty_receive_char_special for an analogous kernel +// function. +// +// Preconditions: +// * l.termiosMu must be held for reading. +// * q.mu must be held. +func (*inputQueueTransformer) transform(l *lineDiscipline, q *queue, buf []byte) int { + // If there's a line waiting to be read in canonical mode, don't write + // anything else to the read buffer. + if l.termios.LEnabled(linux.ICANON) && q.readable { + return 0 + } + + maxBytes := nonCanonMaxBytes + if l.termios.LEnabled(linux.ICANON) { + maxBytes = canonMaxBytes + } + + var ret int + for len(buf) > 0 && len(q.readBuf) < canonMaxBytes { + size := l.peek(buf) + cBytes := append([]byte{}, buf[:size]...) + // We're guaranteed that cBytes has at least one element. + switch cBytes[0] { + case '\r': + if l.termios.IEnabled(linux.IGNCR) { + buf = buf[size:] + ret += size + continue + } + if l.termios.IEnabled(linux.ICRNL) { + cBytes[0] = '\n' + } + case '\n': + if l.termios.IEnabled(linux.INLCR) { + cBytes[0] = '\r' + } + } + + // In canonical mode, we discard non-terminating characters + // after the first 4095. + if l.shouldDiscard(q, cBytes) { + buf = buf[size:] + ret += size + continue + } + + // Stop if the buffer would be overfilled. + if len(q.readBuf)+size > maxBytes { + break + } + buf = buf[size:] + ret += size + + // If we get EOF, make the buffer available for reading. + if l.termios.LEnabled(linux.ICANON) && l.termios.IsEOF(cBytes[0]) { + q.readable = true + break + } + + q.readBuf = append(q.readBuf, cBytes...) + + // Anything written to the readBuf will have to be echoed. + if l.termios.LEnabled(linux.ECHO) { + l.outQueue.writeBytes(cBytes, l) + l.masterWaiter.Notify(waiter.EventIn) + } + + // If we finish a line, make it available for reading. + if l.termios.LEnabled(linux.ICANON) && l.termios.IsTerminating(cBytes) { + q.readable = true + break + } + } + + // In noncanonical mode, everything is readable. + if !l.termios.LEnabled(linux.ICANON) && len(q.readBuf) > 0 { + q.readable = true + } + + return ret +} + +// shouldDiscard returns whether c should be discarded. In canonical mode, if +// too many bytes are enqueued, we keep reading input and discarding it until +// we find a terminating character. Signal/echo processing still occurs. +// +// Precondition: +// * l.termiosMu must be held for reading. +// * q.mu must be held. +func (l *lineDiscipline) shouldDiscard(q *queue, cBytes []byte) bool { + return l.termios.LEnabled(linux.ICANON) && len(q.readBuf)+len(cBytes) >= canonMaxBytes && !l.termios.IsTerminating(cBytes) +} + +// peek returns the size in bytes of the next character to process. As long as +// b isn't empty, peek returns a value of at least 1. +func (l *lineDiscipline) peek(b []byte) int { + size := 1 + // If UTF-8 support is enabled, runes might be multiple bytes. + if l.termios.IEnabled(linux.IUTF8) { + _, size = utf8.DecodeRune(b) + } + return size +} diff --git a/pkg/sentry/fsimpl/devpts/master.go b/pkg/sentry/fsimpl/devpts/master.go new file mode 100644 index 000000000..3bb397f71 --- /dev/null +++ b/pkg/sentry/fsimpl/devpts/master.go @@ -0,0 +1,237 @@ +// 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 devpts + +import ( + "gvisor.dev/gvisor/pkg/abi/linux" + "gvisor.dev/gvisor/pkg/context" + "gvisor.dev/gvisor/pkg/sentry/arch" + fslock "gvisor.dev/gvisor/pkg/sentry/fs/lock" + "gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs" + "gvisor.dev/gvisor/pkg/sentry/kernel/auth" + "gvisor.dev/gvisor/pkg/sentry/unimpl" + "gvisor.dev/gvisor/pkg/sentry/vfs" + "gvisor.dev/gvisor/pkg/syserror" + "gvisor.dev/gvisor/pkg/usermem" + "gvisor.dev/gvisor/pkg/waiter" +) + +// masterInode is the inode for the master end of the Terminal. +type masterInode struct { + kernfs.InodeAttrs + kernfs.InodeNoopRefCount + kernfs.InodeNotDirectory + kernfs.InodeNotSymlink + + locks vfs.FileLocks + + // Keep a reference to this inode's dentry. + dentry kernfs.Dentry + + // root is the devpts root inode. + root *rootInode +} + +var _ kernfs.Inode = (*masterInode)(nil) + +// Open implements kernfs.Inode.Open. +func (mi *masterInode) Open(ctx context.Context, rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) { + t, err := mi.root.allocateTerminal(rp.Credentials()) + if err != nil { + return nil, err + } + + mi.IncRef() + fd := &masterFileDescription{ + inode: mi, + t: t, + } + fd.LockFD.Init(&mi.locks) + if err := fd.vfsfd.Init(fd, opts.Flags, rp.Mount(), vfsd, &vfs.FileDescriptionOptions{}); err != nil { + mi.DecRef(ctx) + return nil, err + } + return &fd.vfsfd, nil +} + +// Stat implements kernfs.Inode.Stat. +func (mi *masterInode) Stat(ctx context.Context, vfsfs *vfs.Filesystem, opts vfs.StatOptions) (linux.Statx, error) { + statx, err := mi.InodeAttrs.Stat(ctx, vfsfs, opts) + if err != nil { + return linux.Statx{}, err + } + statx.Blksize = 1024 + statx.RdevMajor = linux.TTYAUX_MAJOR + statx.RdevMinor = linux.PTMX_MINOR + return statx, nil +} + +// SetStat implements kernfs.Inode.SetStat +func (mi *masterInode) SetStat(ctx context.Context, vfsfs *vfs.Filesystem, creds *auth.Credentials, opts vfs.SetStatOptions) error { + if opts.Stat.Mask&linux.STATX_SIZE != 0 { + return syserror.EINVAL + } + return mi.InodeAttrs.SetStat(ctx, vfsfs, creds, opts) +} + +type masterFileDescription struct { + vfsfd vfs.FileDescription + vfs.FileDescriptionDefaultImpl + vfs.LockFD + + inode *masterInode + t *Terminal +} + +var _ vfs.FileDescriptionImpl = (*masterFileDescription)(nil) + +// Release implements vfs.FileDescriptionImpl.Release. +func (mfd *masterFileDescription) Release(ctx context.Context) { + mfd.inode.root.masterClose(mfd.t) + mfd.inode.DecRef(ctx) +} + +// EventRegister implements waiter.Waitable.EventRegister. +func (mfd *masterFileDescription) EventRegister(e *waiter.Entry, mask waiter.EventMask) { + mfd.t.ld.masterWaiter.EventRegister(e, mask) +} + +// EventUnregister implements waiter.Waitable.EventUnregister. +func (mfd *masterFileDescription) EventUnregister(e *waiter.Entry) { + mfd.t.ld.masterWaiter.EventUnregister(e) +} + +// Readiness implements waiter.Waitable.Readiness. +func (mfd *masterFileDescription) Readiness(mask waiter.EventMask) waiter.EventMask { + return mfd.t.ld.masterReadiness() +} + +// Read implements vfs.FileDescriptionImpl.Read. +func (mfd *masterFileDescription) Read(ctx context.Context, dst usermem.IOSequence, _ vfs.ReadOptions) (int64, error) { + return mfd.t.ld.outputQueueRead(ctx, dst) +} + +// Write implements vfs.FileDescriptionImpl.Write. +func (mfd *masterFileDescription) Write(ctx context.Context, src usermem.IOSequence, _ vfs.WriteOptions) (int64, error) { + return mfd.t.ld.inputQueueWrite(ctx, src) +} + +// Ioctl implements vfs.FileDescriptionImpl.Ioctl. +func (mfd *masterFileDescription) Ioctl(ctx context.Context, io usermem.IO, args arch.SyscallArguments) (uintptr, error) { + switch cmd := args[1].Uint(); cmd { + case linux.FIONREAD: // linux.FIONREAD == linux.TIOCINQ + // Get the number of bytes in the output queue read buffer. + return 0, mfd.t.ld.outputQueueReadSize(ctx, io, args) + case linux.TCGETS: + // N.B. TCGETS on the master actually returns the configuration + // of the slave end. + return mfd.t.ld.getTermios(ctx, io, args) + case linux.TCSETS: + // N.B. TCSETS on the master actually affects the configuration + // of the slave end. + return mfd.t.ld.setTermios(ctx, io, args) + case linux.TCSETSW: + // TODO(b/29356795): This should drain the output queue first. + return mfd.t.ld.setTermios(ctx, io, args) + case linux.TIOCGPTN: + _, err := usermem.CopyObjectOut(ctx, io, args[2].Pointer(), uint32(mfd.t.n), usermem.IOOpts{ + AddressSpaceActive: true, + }) + return 0, err + case linux.TIOCSPTLCK: + // TODO(b/29356795): Implement pty locking. For now just pretend we do. + return 0, nil + case linux.TIOCGWINSZ: + return 0, mfd.t.ld.windowSize(ctx, io, args) + case linux.TIOCSWINSZ: + return 0, mfd.t.ld.setWindowSize(ctx, io, args) + case linux.TIOCSCTTY: + // Make the given terminal the controlling terminal of the + // calling process. + return 0, mfd.t.setControllingTTY(ctx, io, args, true /* isMaster */) + case linux.TIOCNOTTY: + // Release this process's controlling terminal. + return 0, mfd.t.releaseControllingTTY(ctx, io, args, true /* isMaster */) + case linux.TIOCGPGRP: + // Get the foreground process group. + return mfd.t.foregroundProcessGroup(ctx, io, args, true /* isMaster */) + case linux.TIOCSPGRP: + // Set the foreground process group. + return mfd.t.setForegroundProcessGroup(ctx, io, args, true /* isMaster */) + default: + maybeEmitUnimplementedEvent(ctx, cmd) + return 0, syserror.ENOTTY + } +} + +// SetStat implements vfs.FileDescriptionImpl.SetStat. +func (mfd *masterFileDescription) SetStat(ctx context.Context, opts vfs.SetStatOptions) error { + creds := auth.CredentialsFromContext(ctx) + fs := mfd.vfsfd.VirtualDentry().Mount().Filesystem() + return mfd.inode.SetStat(ctx, fs, creds, opts) +} + +// Stat implements vfs.FileDescriptionImpl.Stat. +func (mfd *masterFileDescription) Stat(ctx context.Context, opts vfs.StatOptions) (linux.Statx, error) { + fs := mfd.vfsfd.VirtualDentry().Mount().Filesystem() + return mfd.inode.Stat(ctx, fs, opts) +} + +// LockPOSIX implements vfs.FileDescriptionImpl.LockPOSIX. +func (mfd *masterFileDescription) LockPOSIX(ctx context.Context, uid fslock.UniqueID, t fslock.LockType, start, length uint64, whence int16, block fslock.Blocker) error { + return mfd.Locks().LockPOSIX(ctx, &mfd.vfsfd, uid, t, start, length, whence, block) +} + +// UnlockPOSIX implements vfs.FileDescriptionImpl.UnlockPOSIX. +func (mfd *masterFileDescription) UnlockPOSIX(ctx context.Context, uid fslock.UniqueID, start, length uint64, whence int16) error { + return mfd.Locks().UnlockPOSIX(ctx, &mfd.vfsfd, uid, start, length, whence) +} + +// maybeEmitUnimplementedEvent emits unimplemented event if cmd is valid. +func maybeEmitUnimplementedEvent(ctx context.Context, cmd uint32) { + switch cmd { + case linux.TCGETS, + linux.TCSETS, + linux.TCSETSW, + linux.TCSETSF, + linux.TIOCGWINSZ, + linux.TIOCSWINSZ, + linux.TIOCSETD, + linux.TIOCSBRK, + linux.TIOCCBRK, + linux.TCSBRK, + linux.TCSBRKP, + linux.TIOCSTI, + linux.TIOCCONS, + linux.FIONBIO, + linux.TIOCEXCL, + linux.TIOCNXCL, + linux.TIOCGEXCL, + linux.TIOCGSID, + linux.TIOCGETD, + linux.TIOCVHANGUP, + linux.TIOCGDEV, + linux.TIOCMGET, + linux.TIOCMSET, + linux.TIOCMBIC, + linux.TIOCMBIS, + linux.TIOCGICOUNT, + linux.TCFLSH, + linux.TIOCSSERIAL, + linux.TIOCGPTPEER: + + unimpl.EmitUnimplementedEvent(ctx) + } +} diff --git a/pkg/sentry/fsimpl/devpts/queue.go b/pkg/sentry/fsimpl/devpts/queue.go new file mode 100644 index 000000000..dffb4232c --- /dev/null +++ b/pkg/sentry/fsimpl/devpts/queue.go @@ -0,0 +1,236 @@ +// Copyright 2018 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package devpts + +import ( + "gvisor.dev/gvisor/pkg/abi/linux" + "gvisor.dev/gvisor/pkg/context" + "gvisor.dev/gvisor/pkg/safemem" + "gvisor.dev/gvisor/pkg/sentry/arch" + "gvisor.dev/gvisor/pkg/sync" + "gvisor.dev/gvisor/pkg/syserror" + "gvisor.dev/gvisor/pkg/usermem" + "gvisor.dev/gvisor/pkg/waiter" +) + +// waitBufMaxBytes is the maximum size of a wait buffer. It is based on +// TTYB_DEFAULT_MEM_LIMIT. +const waitBufMaxBytes = 131072 + +// queue represents one of the input or output queues between a pty master and +// slave. Bytes written to a queue are added to the read buffer until it is +// full, at which point they are written to the wait buffer. Bytes are +// processed (i.e. undergo termios transformations) as they are added to the +// read buffer. The read buffer is readable when its length is nonzero and +// readable is true. +// +// +stateify savable +type queue struct { + // mu protects everything in queue. + mu sync.Mutex `state:"nosave"` + + // readBuf is buffer of data ready to be read when readable is true. + // This data has been processed. + readBuf []byte + + // waitBuf contains data that can't fit into readBuf. It is put here + // until it can be loaded into the read buffer. waitBuf contains data + // that hasn't been processed. + waitBuf [][]byte + waitBufLen uint64 + + // readable indicates whether the read buffer can be read from. In + // canonical mode, there can be an unterminated line in the read buffer, + // so readable must be checked. + readable bool + + // transform is the the queue's function for transforming bytes + // entering the queue. For example, transform might convert all '\r's + // entering the queue to '\n's. + transformer +} + +// readReadiness returns whether q is ready to be read from. +func (q *queue) readReadiness(t *linux.KernelTermios) waiter.EventMask { + q.mu.Lock() + defer q.mu.Unlock() + if len(q.readBuf) > 0 && q.readable { + return waiter.EventIn + } + return waiter.EventMask(0) +} + +// writeReadiness returns whether q is ready to be written to. +func (q *queue) writeReadiness(t *linux.KernelTermios) waiter.EventMask { + q.mu.Lock() + defer q.mu.Unlock() + if q.waitBufLen < waitBufMaxBytes { + return waiter.EventOut + } + return waiter.EventMask(0) +} + +// readableSize writes the number of readable bytes to userspace. +func (q *queue) readableSize(ctx context.Context, io usermem.IO, args arch.SyscallArguments) error { + q.mu.Lock() + defer q.mu.Unlock() + var size int32 + if q.readable { + size = int32(len(q.readBuf)) + } + + _, err := usermem.CopyObjectOut(ctx, io, args[2].Pointer(), size, usermem.IOOpts{ + AddressSpaceActive: true, + }) + return err + +} + +// read reads from q to userspace. It returns the number of bytes read as well +// as whether the read caused more readable data to become available (whether +// data was pushed from the wait buffer to the read buffer). +// +// Preconditions: +// * l.termiosMu must be held for reading. +func (q *queue) read(ctx context.Context, dst usermem.IOSequence, l *lineDiscipline) (int64, bool, error) { + q.mu.Lock() + defer q.mu.Unlock() + + if !q.readable { + return 0, false, syserror.ErrWouldBlock + } + + if dst.NumBytes() > canonMaxBytes { + dst = dst.TakeFirst(canonMaxBytes) + } + + n, err := dst.CopyOutFrom(ctx, safemem.ReaderFunc(func(dst safemem.BlockSeq) (uint64, error) { + src := safemem.BlockSeqOf(safemem.BlockFromSafeSlice(q.readBuf)) + n, err := safemem.CopySeq(dst, src) + if err != nil { + return 0, err + } + q.readBuf = q.readBuf[n:] + + // If we read everything, this queue is no longer readable. + if len(q.readBuf) == 0 { + q.readable = false + } + + return n, nil + })) + if err != nil { + return 0, false, err + } + + // Move data from the queue's wait buffer to its read buffer. + nPushed := q.pushWaitBufLocked(l) + + return int64(n), nPushed > 0, nil +} + +// write writes to q from userspace. +// +// Preconditions: +// * l.termiosMu must be held for reading. +func (q *queue) write(ctx context.Context, src usermem.IOSequence, l *lineDiscipline) (int64, error) { + q.mu.Lock() + defer q.mu.Unlock() + + // Copy data into the wait buffer. + n, err := src.CopyInTo(ctx, safemem.WriterFunc(func(src safemem.BlockSeq) (uint64, error) { + copyLen := src.NumBytes() + room := waitBufMaxBytes - q.waitBufLen + // If out of room, return EAGAIN. + if room == 0 && copyLen > 0 { + return 0, syserror.ErrWouldBlock + } + // Cap the size of the wait buffer. + if copyLen > room { + copyLen = room + src = src.TakeFirst64(room) + } + buf := make([]byte, copyLen) + + // Copy the data into the wait buffer. + dst := safemem.BlockSeqOf(safemem.BlockFromSafeSlice(buf)) + n, err := safemem.CopySeq(dst, src) + if err != nil { + return 0, err + } + q.waitBufAppend(buf) + + return n, nil + })) + if err != nil { + return 0, err + } + + // Push data from the wait to the read buffer. + q.pushWaitBufLocked(l) + + return n, nil +} + +// writeBytes writes to q from b. +// +// Preconditions: +// * l.termiosMu must be held for reading. +func (q *queue) writeBytes(b []byte, l *lineDiscipline) { + q.mu.Lock() + defer q.mu.Unlock() + + // Write to the wait buffer. + q.waitBufAppend(b) + q.pushWaitBufLocked(l) +} + +// pushWaitBufLocked fills the queue's read buffer with data from the wait +// buffer. +// +// Preconditions: +// * l.termiosMu must be held for reading. +// * q.mu must be locked. +func (q *queue) pushWaitBufLocked(l *lineDiscipline) int { + if q.waitBufLen == 0 { + return 0 + } + + // Move data from the wait to the read buffer. + var total int + var i int + for i = 0; i < len(q.waitBuf); i++ { + n := q.transform(l, q, q.waitBuf[i]) + total += n + if n != len(q.waitBuf[i]) { + // The read buffer filled up without consuming the + // entire buffer. + q.waitBuf[i] = q.waitBuf[i][n:] + break + } + } + + // Update wait buffer based on consumed data. + q.waitBuf = q.waitBuf[i:] + q.waitBufLen -= uint64(total) + + return total +} + +// Precondition: q.mu must be locked. +func (q *queue) waitBufAppend(b []byte) { + q.waitBuf = append(q.waitBuf, b) + q.waitBufLen += uint64(len(b)) +} diff --git a/pkg/sentry/fsimpl/devpts/slave.go b/pkg/sentry/fsimpl/devpts/slave.go new file mode 100644 index 000000000..32e4e1908 --- /dev/null +++ b/pkg/sentry/fsimpl/devpts/slave.go @@ -0,0 +1,197 @@ +// 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 devpts + +import ( + "gvisor.dev/gvisor/pkg/abi/linux" + "gvisor.dev/gvisor/pkg/context" + "gvisor.dev/gvisor/pkg/sentry/arch" + fslock "gvisor.dev/gvisor/pkg/sentry/fs/lock" + "gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs" + "gvisor.dev/gvisor/pkg/sentry/kernel/auth" + "gvisor.dev/gvisor/pkg/sentry/vfs" + "gvisor.dev/gvisor/pkg/syserror" + "gvisor.dev/gvisor/pkg/usermem" + "gvisor.dev/gvisor/pkg/waiter" +) + +// slaveInode is the inode for the slave end of the Terminal. +type slaveInode struct { + kernfs.InodeAttrs + kernfs.InodeNoopRefCount + kernfs.InodeNotDirectory + kernfs.InodeNotSymlink + + locks vfs.FileLocks + + // Keep a reference to this inode's dentry. + dentry kernfs.Dentry + + // root is the devpts root inode. + root *rootInode + + // t is the connected Terminal. + t *Terminal +} + +var _ kernfs.Inode = (*slaveInode)(nil) + +// Open implements kernfs.Inode.Open. +func (si *slaveInode) Open(ctx context.Context, rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) { + si.IncRef() + fd := &slaveFileDescription{ + inode: si, + } + fd.LockFD.Init(&si.locks) + if err := fd.vfsfd.Init(fd, opts.Flags, rp.Mount(), vfsd, &vfs.FileDescriptionOptions{}); err != nil { + si.DecRef(ctx) + return nil, err + } + return &fd.vfsfd, nil + +} + +// Valid implements kernfs.Inode.Valid. +func (si *slaveInode) Valid(context.Context) bool { + // Return valid if the slave still exists. + si.root.mu.Lock() + defer si.root.mu.Unlock() + _, ok := si.root.slaves[si.t.n] + return ok +} + +// Stat implements kernfs.Inode.Stat. +func (si *slaveInode) Stat(ctx context.Context, vfsfs *vfs.Filesystem, opts vfs.StatOptions) (linux.Statx, error) { + statx, err := si.InodeAttrs.Stat(ctx, vfsfs, opts) + if err != nil { + return linux.Statx{}, err + } + statx.Blksize = 1024 + statx.RdevMajor = linux.UNIX98_PTY_SLAVE_MAJOR + statx.RdevMinor = si.t.n + return statx, nil +} + +// SetStat implements kernfs.Inode.SetStat +func (si *slaveInode) SetStat(ctx context.Context, vfsfs *vfs.Filesystem, creds *auth.Credentials, opts vfs.SetStatOptions) error { + if opts.Stat.Mask&linux.STATX_SIZE != 0 { + return syserror.EINVAL + } + return si.InodeAttrs.SetStat(ctx, vfsfs, creds, opts) +} + +type slaveFileDescription struct { + vfsfd vfs.FileDescription + vfs.FileDescriptionDefaultImpl + vfs.LockFD + + inode *slaveInode +} + +var _ vfs.FileDescriptionImpl = (*slaveFileDescription)(nil) + +// Release implements fs.FileOperations.Release. +func (sfd *slaveFileDescription) Release(ctx context.Context) { + sfd.inode.DecRef(ctx) +} + +// EventRegister implements waiter.Waitable.EventRegister. +func (sfd *slaveFileDescription) EventRegister(e *waiter.Entry, mask waiter.EventMask) { + sfd.inode.t.ld.slaveWaiter.EventRegister(e, mask) +} + +// EventUnregister implements waiter.Waitable.EventUnregister. +func (sfd *slaveFileDescription) EventUnregister(e *waiter.Entry) { + sfd.inode.t.ld.slaveWaiter.EventUnregister(e) +} + +// Readiness implements waiter.Waitable.Readiness. +func (sfd *slaveFileDescription) Readiness(mask waiter.EventMask) waiter.EventMask { + return sfd.inode.t.ld.slaveReadiness() +} + +// Read implements vfs.FileDescriptionImpl.Read. +func (sfd *slaveFileDescription) Read(ctx context.Context, dst usermem.IOSequence, _ vfs.ReadOptions) (int64, error) { + return sfd.inode.t.ld.inputQueueRead(ctx, dst) +} + +// Write implements vfs.FileDescriptionImpl.Write. +func (sfd *slaveFileDescription) Write(ctx context.Context, src usermem.IOSequence, _ vfs.WriteOptions) (int64, error) { + return sfd.inode.t.ld.outputQueueWrite(ctx, src) +} + +// Ioctl implements vfs.FileDescriptionImpl.Ioctl. +func (sfd *slaveFileDescription) Ioctl(ctx context.Context, io usermem.IO, args arch.SyscallArguments) (uintptr, error) { + switch cmd := args[1].Uint(); cmd { + case linux.FIONREAD: // linux.FIONREAD == linux.TIOCINQ + // Get the number of bytes in the input queue read buffer. + return 0, sfd.inode.t.ld.inputQueueReadSize(ctx, io, args) + case linux.TCGETS: + return sfd.inode.t.ld.getTermios(ctx, io, args) + case linux.TCSETS: + return sfd.inode.t.ld.setTermios(ctx, io, args) + case linux.TCSETSW: + // TODO(b/29356795): This should drain the output queue first. + return sfd.inode.t.ld.setTermios(ctx, io, args) + case linux.TIOCGPTN: + _, err := usermem.CopyObjectOut(ctx, io, args[2].Pointer(), uint32(sfd.inode.t.n), usermem.IOOpts{ + AddressSpaceActive: true, + }) + return 0, err + case linux.TIOCGWINSZ: + return 0, sfd.inode.t.ld.windowSize(ctx, io, args) + case linux.TIOCSWINSZ: + return 0, sfd.inode.t.ld.setWindowSize(ctx, io, args) + case linux.TIOCSCTTY: + // Make the given terminal the controlling terminal of the + // calling process. + return 0, sfd.inode.t.setControllingTTY(ctx, io, args, false /* isMaster */) + case linux.TIOCNOTTY: + // Release this process's controlling terminal. + return 0, sfd.inode.t.releaseControllingTTY(ctx, io, args, false /* isMaster */) + case linux.TIOCGPGRP: + // Get the foreground process group. + return sfd.inode.t.foregroundProcessGroup(ctx, io, args, false /* isMaster */) + case linux.TIOCSPGRP: + // Set the foreground process group. + return sfd.inode.t.setForegroundProcessGroup(ctx, io, args, false /* isMaster */) + default: + maybeEmitUnimplementedEvent(ctx, cmd) + return 0, syserror.ENOTTY + } +} + +// SetStat implements vfs.FileDescriptionImpl.SetStat. +func (sfd *slaveFileDescription) SetStat(ctx context.Context, opts vfs.SetStatOptions) error { + creds := auth.CredentialsFromContext(ctx) + fs := sfd.vfsfd.VirtualDentry().Mount().Filesystem() + return sfd.inode.SetStat(ctx, fs, creds, opts) +} + +// Stat implements vfs.FileDescriptionImpl.Stat. +func (sfd *slaveFileDescription) Stat(ctx context.Context, opts vfs.StatOptions) (linux.Statx, error) { + fs := sfd.vfsfd.VirtualDentry().Mount().Filesystem() + return sfd.inode.Stat(ctx, fs, opts) +} + +// LockPOSIX implements vfs.FileDescriptionImpl.LockPOSIX. +func (sfd *slaveFileDescription) LockPOSIX(ctx context.Context, uid fslock.UniqueID, t fslock.LockType, start, length uint64, whence int16, block fslock.Blocker) error { + return sfd.Locks().LockPOSIX(ctx, &sfd.vfsfd, uid, t, start, length, whence, block) +} + +// UnlockPOSIX implements vfs.FileDescriptionImpl.UnlockPOSIX. +func (sfd *slaveFileDescription) UnlockPOSIX(ctx context.Context, uid fslock.UniqueID, start, length uint64, whence int16) error { + return sfd.Locks().UnlockPOSIX(ctx, &sfd.vfsfd, uid, start, length, whence) +} diff --git a/pkg/sentry/fsimpl/devpts/terminal.go b/pkg/sentry/fsimpl/devpts/terminal.go new file mode 100644 index 000000000..7d2781c54 --- /dev/null +++ b/pkg/sentry/fsimpl/devpts/terminal.go @@ -0,0 +1,120 @@ +// Copyright 2018 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package devpts + +import ( + "gvisor.dev/gvisor/pkg/abi/linux" + "gvisor.dev/gvisor/pkg/context" + "gvisor.dev/gvisor/pkg/sentry/arch" + "gvisor.dev/gvisor/pkg/sentry/kernel" + "gvisor.dev/gvisor/pkg/usermem" +) + +// Terminal is a pseudoterminal. +// +// +stateify savable +type Terminal struct { + // n is the terminal index. It is immutable. + n uint32 + + // ld is the line discipline of the terminal. It is immutable. + ld *lineDiscipline + + // masterKTTY contains the controlling process of the master end of + // this terminal. This field is immutable. + masterKTTY *kernel.TTY + + // slaveKTTY contains the controlling process of the slave end of this + // terminal. This field is immutable. + slaveKTTY *kernel.TTY +} + +func newTerminal(n uint32) *Terminal { + termios := linux.DefaultSlaveTermios + t := Terminal{ + n: n, + ld: newLineDiscipline(termios), + masterKTTY: &kernel.TTY{Index: n}, + slaveKTTY: &kernel.TTY{Index: n}, + } + return &t +} + +// setControllingTTY makes tm the controlling terminal of the calling thread +// group. +func (tm *Terminal) setControllingTTY(ctx context.Context, io usermem.IO, args arch.SyscallArguments, isMaster bool) error { + task := kernel.TaskFromContext(ctx) + if task == nil { + panic("setControllingTTY must be called from a task context") + } + + return task.ThreadGroup().SetControllingTTY(tm.tty(isMaster), args[2].Int()) +} + +// releaseControllingTTY removes tm as the controlling terminal of the calling +// thread group. +func (tm *Terminal) releaseControllingTTY(ctx context.Context, io usermem.IO, args arch.SyscallArguments, isMaster bool) error { + task := kernel.TaskFromContext(ctx) + if task == nil { + panic("releaseControllingTTY must be called from a task context") + } + + return task.ThreadGroup().ReleaseControllingTTY(tm.tty(isMaster)) +} + +// foregroundProcessGroup gets the process group ID of tm's foreground process. +func (tm *Terminal) foregroundProcessGroup(ctx context.Context, io usermem.IO, args arch.SyscallArguments, isMaster bool) (uintptr, error) { + task := kernel.TaskFromContext(ctx) + if task == nil { + panic("foregroundProcessGroup must be called from a task context") + } + + ret, err := task.ThreadGroup().ForegroundProcessGroup(tm.tty(isMaster)) + if err != nil { + return 0, err + } + + // Write it out to *arg. + _, err = usermem.CopyObjectOut(ctx, io, args[2].Pointer(), int32(ret), usermem.IOOpts{ + AddressSpaceActive: true, + }) + return 0, err +} + +// foregroundProcessGroup sets tm's foreground process. +func (tm *Terminal) setForegroundProcessGroup(ctx context.Context, io usermem.IO, args arch.SyscallArguments, isMaster bool) (uintptr, error) { + task := kernel.TaskFromContext(ctx) + if task == nil { + panic("setForegroundProcessGroup must be called from a task context") + } + + // Read in the process group ID. + var pgid int32 + if _, err := usermem.CopyObjectIn(ctx, io, args[2].Pointer(), &pgid, usermem.IOOpts{ + AddressSpaceActive: true, + }); err != nil { + return 0, err + } + + ret, err := task.ThreadGroup().SetForegroundProcessGroup(tm.tty(isMaster), kernel.ProcessGroupID(pgid)) + return uintptr(ret), err +} + +func (tm *Terminal) tty(isMaster bool) *kernel.TTY { + if isMaster { + return tm.masterKTTY + } + return tm.slaveKTTY +} |