diff options
Diffstat (limited to 'pkg/sentry/fs/tty')
| -rw-r--r-- | pkg/sentry/fs/tty/BUILD | 2 | ||||
| -rw-r--r-- | pkg/sentry/fs/tty/line_discipline.go | 252 | ||||
| -rw-r--r-- | pkg/sentry/fs/tty/queue.go | 218 |
3 files changed, 242 insertions, 230 deletions
diff --git a/pkg/sentry/fs/tty/BUILD b/pkg/sentry/fs/tty/BUILD index 90b350410..fce327dfe 100644 --- a/pkg/sentry/fs/tty/BUILD +++ b/pkg/sentry/fs/tty/BUILD @@ -11,6 +11,7 @@ go_stateify( "inode.go", "line_discipline.go", "master.go", + "queue.go", "slave.go", "terminal.go", ], @@ -26,6 +27,7 @@ go_library( "inode.go", "line_discipline.go", "master.go", + "queue.go", "slave.go", "terminal.go", "tty_state.go", diff --git a/pkg/sentry/fs/tty/line_discipline.go b/pkg/sentry/fs/tty/line_discipline.go index a4012135c..f094635f5 100644 --- a/pkg/sentry/fs/tty/line_discipline.go +++ b/pkg/sentry/fs/tty/line_discipline.go @@ -23,7 +23,6 @@ import ( "gvisor.googlesource.com/gvisor/pkg/sentry/arch" "gvisor.googlesource.com/gvisor/pkg/sentry/context" "gvisor.googlesource.com/gvisor/pkg/sentry/usermem" - "gvisor.googlesource.com/gvisor/pkg/syserror" "gvisor.googlesource.com/gvisor/pkg/waiter" ) @@ -38,97 +37,8 @@ const ( nonCanonMaxBytes = canonMaxBytes - 1 spacesPerTab = 8 - - // transformInputStateifyKey is used to save and restore queues. - transformInputStateifyKey = "transformInput" - - // transformOutputStateifyKey is used to save and restore queues. - transformOutputStateifyKey = "transformOutput" ) -// 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 -} - -// 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. -type queue struct { - waiter.Queue `state:"nosave"` - - // readBuf is buffer of data ready to be read when readable is true. - // This data has been processed. - readBuf bytes.Buffer `state:".([]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 bytes.Buffer `state:".([]byte)"` - - // 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 -} - -// saveReadBuf is invoked by stateify. -func (q *queue) saveReadBuf() []byte { - return append([]byte(nil), q.readBuf.Bytes()...) -} - -// loadReadBuf is invoked by stateify. -func (q *queue) loadReadBuf(b []byte) { - q.readBuf.Write(b) -} - -// saveWaitBuf is invoked by stateify. -func (q *queue) saveWaitBuf() []byte { - return append([]byte(nil), q.waitBuf.Bytes()...) -} - -// loadWaitBuf is invoked by stateify. -func (q *queue) loadWaitBuf(b []byte) { - q.waitBuf.Write(b) -} - -// readReadiness returns whether q is ready to be read from. -func (q *queue) readReadiness(t *linux.KernelTermios) waiter.EventMask { - if q.readBuf.Len() > 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 { - // Like Linux, we don't impose a maximum size on what can be enqueued. - return waiter.EventOut -} - -// readableSize writes the number of readable bytes to userspace. -func (q *queue) readableSize(ctx context.Context, io usermem.IO, args arch.SyscallArguments) error { - var size int32 - if q.readable { - size = int32(q.readBuf.Len()) - } - - _, err := usermem.CopyObjectOut(ctx, io, args[2].Pointer(), size, usermem.IOOpts{ - AddressSpaceActive: true, - }) - return err - -} - // 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 @@ -160,18 +70,12 @@ func (q *queue) readableSize(ctx context.Context, io usermem.IO, args arch.Sysca // // Lock order: // termiosMu -// inMu -// outMu +// inQueue.mu +// outQueue.mu type lineDiscipline struct { - // inMu protects inQueue. - inMu sync.Mutex `state:"nosave"` - // inQueue is the input queue of the terminal. inQueue queue - // outMu protects outQueue. - outMu sync.Mutex `state:"nosave"` - // outQueue is the output queue of the terminal. outQueue queue @@ -209,8 +113,6 @@ func (l *lineDiscipline) getTermios(ctx context.Context, io usermem.IO, args arc func (l *lineDiscipline) setTermios(ctx context.Context, io usermem.IO, args arch.SyscallArguments) (uintptr, error) { l.termiosMu.Lock() defer l.termiosMu.Unlock() - l.inMu.Lock() - defer l.inMu.Unlock() oldCanonEnabled := l.termios.LEnabled(linux.ICANON) // We must copy a Termios struct, not KernelTermios. var t linux.Termios @@ -223,17 +125,13 @@ func (l *lineDiscipline) setTermios(ctx context.Context, io usermem.IO, args arc // buffer to its read buffer. Anything already in the read buffer is // now readable. if oldCanonEnabled && !l.termios.LEnabled(linux.ICANON) { - l.pushWaitBuf(&l.inQueue) + l.inQueue.pushWaitBuf(l) } return 0, err } func (l *lineDiscipline) masterReadiness() waiter.EventMask { - l.inMu.Lock() - defer l.inMu.Unlock() - l.outMu.Lock() - defer l.outMu.Unlock() // 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) @@ -242,156 +140,49 @@ func (l *lineDiscipline) masterReadiness() waiter.EventMask { func (l *lineDiscipline) slaveReadiness() waiter.EventMask { l.termiosMu.RLock() defer l.termiosMu.RUnlock() - l.inMu.Lock() - defer l.inMu.Unlock() - l.outMu.Lock() - defer l.outMu.Unlock() 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 { - l.inMu.Lock() - defer l.inMu.Unlock() 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() - l.inMu.Lock() - defer l.inMu.Unlock() - return l.queueRead(ctx, dst, &l.inQueue) + return l.inQueue.read(ctx, dst, l) } func (l *lineDiscipline) inputQueueWrite(ctx context.Context, src usermem.IOSequence) (int64, error) { l.termiosMu.RLock() defer l.termiosMu.RUnlock() - l.inMu.Lock() - defer l.inMu.Unlock() - return l.queueWrite(ctx, src, &l.inQueue) + return l.inQueue.write(ctx, src, l) } func (l *lineDiscipline) outputQueueReadSize(ctx context.Context, io usermem.IO, args arch.SyscallArguments) error { - l.outMu.Lock() - defer l.outMu.Unlock() 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() - l.outMu.Lock() - defer l.outMu.Unlock() - return l.queueRead(ctx, dst, &l.outQueue) + return l.outQueue.read(ctx, dst, l) } func (l *lineDiscipline) outputQueueWrite(ctx context.Context, src usermem.IOSequence) (int64, error) { l.termiosMu.RLock() defer l.termiosMu.RUnlock() - l.outMu.Lock() - defer l.outMu.Unlock() - return l.queueWrite(ctx, src, &l.outQueue) + return l.outQueue.write(ctx, src, l) } -// queueRead reads from q to userspace. -// -// Preconditions: -// * l.termiosMu must be held for reading. -// * q's lock must be held. -func (l *lineDiscipline) queueRead(ctx context.Context, dst usermem.IOSequence, q *queue) (int64, error) { - if !q.readable { - return 0, syserror.ErrWouldBlock - } - - // Read out from the read buffer. - n := canonMaxBytes - if n > int(dst.NumBytes()) { - n = int(dst.NumBytes()) - } - if n > q.readBuf.Len() { - n = q.readBuf.Len() - } - n, err := dst.Writer(ctx).Write(q.readBuf.Bytes()[:n]) - if err != nil { - return 0, err - } - // Discard bytes read out. - q.readBuf.Next(n) - - // If we read everything, this queue is no longer readable. - if q.readBuf.Len() == 0 { - q.readable = false - } - - // Move data from the queue's wait buffer to its read buffer. - l.pushWaitBuf(q) - - // If state changed, notify any waiters. If nothing was available to - // read, let the caller know we could block. - if n > 0 { - q.Notify(waiter.EventOut) - } else { - return 0, syserror.ErrWouldBlock - } - return int64(n), nil -} - -// queueWrite writes to q from userspace. -// -// Preconditions: -// * l.termiosMu must be held for reading. -// * q's lock must be held. -func (l *lineDiscipline) queueWrite(ctx context.Context, src usermem.IOSequence, q *queue) (int64, error) { - // TODO: Use CopyInTo/safemem to avoid extra copying. - // Copy in the bytes to write from user-space. - b := make([]byte, src.NumBytes()) - n, err := src.CopyIn(ctx, b) - if err != nil { - return 0, err - } - b = b[:n] - return l.queueWriteBytes(b, q) -} - -// queueWriteBytes writes to q from b. -// -// Precondition: -// * l.termiosMu must be held for reading. -// * q's lock must be held. -func (l *lineDiscipline) queueWriteBytes(b []byte, q *queue) (int64, error) { - // Write as much as possible to the read buffer. - n := q.transform(l, q, b) - - // Write remaining data to the wait buffer. - nWaiting, _ := q.waitBuf.Write(b[n:]) - - // If state changed, notify any waiters. If we were unable to write - // anything, let the caller know we could block. - if n > 0 { - q.Notify(waiter.EventIn) - } else if nWaiting == 0 { - return 0, syserror.ErrWouldBlock - } - return int64(n + nWaiting), nil -} - -// pushWaitBuf fills the queue's read buffer with data from the wait buffer. -// -// Precondition: -// * l.termiosMu must be held for reading. -// * l.inMu must be held. -func (l *lineDiscipline) pushWaitBuf(q *queue) { - // Remove bytes from the wait buffer and move them to the read buffer. - n := q.transform(l, q, q.waitBuf.Bytes()) - q.waitBuf.Next(n) - - // If state changed, notify any waiters. - if n > 0 { - q.Notify(waiter.EventIn) - } +// 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. +// outputQueueTransformer implements transformer. It performs line discipline +// transformations on the output queue. type outputQueueTransformer struct{} // transform does output processing for one end of the pty. See @@ -399,7 +190,7 @@ type outputQueueTransformer struct{} // // Precondition: // * l.termiosMu must be held for reading. -// * q's mutex must be held. +// * 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. @@ -461,7 +252,8 @@ func (*outputQueueTransformer) transform(l *lineDiscipline, q *queue, buf []byte return ret } -// inputQueueTransformer implements transformer. +// inputQueueTransformer implements transformer. It performs line discipline +// transformations on the input queue. type inputQueueTransformer struct{} // transform does input processing for one end of the pty. Characters read are @@ -471,7 +263,7 @@ type inputQueueTransformer struct{} // // Precondition: // * l.termiosMu must be held for reading. -// * q's mutex must be held. +// * 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. @@ -528,11 +320,7 @@ func (*inputQueueTransformer) transform(l *lineDiscipline, q *queue, buf []byte) q.readBuf.WriteRune(c) // Anything written to the readBuf will have to be echoed. if l.termios.LEnabled(linux.ECHO) { - // We can't defer Unlock here because we may - // Lock/Unlock l.outMu multiple times in this loop. - l.outMu.Lock() - l.queueWriteBytes(cBytes, &l.outQueue) - l.outMu.Unlock() + l.outQueue.writeBytes(cBytes, l) } // If we finish a line, make it available for reading. @@ -553,6 +341,10 @@ func (*inputQueueTransformer) transform(l *lineDiscipline, q *queue, buf []byte) // 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, c rune) bool { return l.termios.LEnabled(linux.ICANON) && q.readBuf.Len()+utf8.RuneLen(c) >= canonMaxBytes && !l.termios.IsTerminating(c) } diff --git a/pkg/sentry/fs/tty/queue.go b/pkg/sentry/fs/tty/queue.go new file mode 100644 index 000000000..026d5e077 --- /dev/null +++ b/pkg/sentry/fs/tty/queue.go @@ -0,0 +1,218 @@ +// Copyright 2018 Google Inc. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package tty + +import ( + "bytes" + "sync" + + "gvisor.googlesource.com/gvisor/pkg/abi/linux" + "gvisor.googlesource.com/gvisor/pkg/sentry/arch" + "gvisor.googlesource.com/gvisor/pkg/sentry/context" + "gvisor.googlesource.com/gvisor/pkg/sentry/usermem" + "gvisor.googlesource.com/gvisor/pkg/syserror" + "gvisor.googlesource.com/gvisor/pkg/waiter" +) + +// 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. +type queue struct { + // mu protects everything in queue. + mu sync.Mutex `state:"nosave"` + + waiter.Queue `state:"nosave"` + + // readBuf is buffer of data ready to be read when readable is true. + // This data has been processed. + readBuf bytes.Buffer `state:".([]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 bytes.Buffer `state:".([]byte)"` + + // 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 +} + +// saveReadBuf is invoked by stateify. +func (q *queue) saveReadBuf() []byte { + return append([]byte(nil), q.readBuf.Bytes()...) +} + +// loadReadBuf is invoked by stateify. +func (q *queue) loadReadBuf(b []byte) { + q.readBuf.Write(b) +} + +// saveWaitBuf is invoked by stateify. +func (q *queue) saveWaitBuf() []byte { + return append([]byte(nil), q.waitBuf.Bytes()...) +} + +// loadWaitBuf is invoked by stateify. +func (q *queue) loadWaitBuf(b []byte) { + q.waitBuf.Write(b) +} + +// 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 q.readBuf.Len() > 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 { + // Like Linux, we don't impose a maximum size on what can be enqueued. + return waiter.EventOut +} + +// 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(q.readBuf.Len()) + } + + _, err := usermem.CopyObjectOut(ctx, io, args[2].Pointer(), size, usermem.IOOpts{ + AddressSpaceActive: true, + }) + return err + +} + +// read reads from q to userspace. +// +// Preconditions: +// * l.termiosMu must be held for reading. +func (q *queue) read(ctx context.Context, dst usermem.IOSequence, l *lineDiscipline) (int64, error) { + q.mu.Lock() + defer q.mu.Unlock() + if !q.readable { + return 0, syserror.ErrWouldBlock + } + + // Read out from the read buffer. + n := canonMaxBytes + if n > int(dst.NumBytes()) { + n = int(dst.NumBytes()) + } + if n > q.readBuf.Len() { + n = q.readBuf.Len() + } + n, err := dst.Writer(ctx).Write(q.readBuf.Bytes()[:n]) + if err != nil { + return 0, err + } + // Discard bytes read out. + q.readBuf.Next(n) + + // If we read everything, this queue is no longer readable. + if q.readBuf.Len() == 0 { + q.readable = false + } + + // Move data from the queue's wait buffer to its read buffer. + q.pushWaitBufLocked(l) + + // If state changed, notify any waiters. If nothing was available to + // read, let the caller know we could block. + if n > 0 { + q.Notify(waiter.EventOut) + } else { + return 0, syserror.ErrWouldBlock + } + return int64(n), 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) { + // TODO: Use CopyInTo/safemem to avoid extra copying. + // Copy in the bytes to write from user-space. + b := make([]byte, src.NumBytes()) + n, err := src.CopyIn(ctx, b) + if err != nil { + return 0, err + } + b = b[:n] + return q.writeBytes(b, l) +} + +// writeBytes writes to q from b. +// +// Preconditions: +// * l.termiosMu must be held for reading. +func (q *queue) writeBytes(b []byte, l *lineDiscipline) (int64, error) { + q.mu.Lock() + defer q.mu.Unlock() + // Write as much as possible to the read buffer. + n := q.transform(l, q, b) + + // Write remaining data to the wait buffer. + nWaiting, _ := q.waitBuf.Write(b[n:]) + + // If state changed, notify any waiters. If we were unable to write + // anything, let the caller know we could block. + if n > 0 { + q.Notify(waiter.EventIn) + } else if nWaiting == 0 { + return 0, syserror.ErrWouldBlock + } + return int64(n + nWaiting), nil +} + +// pushWaitBuf fills the queue's read buffer with data from the wait buffer. +// +// Preconditions: +// * l.termiosMu must be held for reading. +func (q *queue) pushWaitBuf(l *lineDiscipline) { + q.mu.Lock() + defer q.mu.Unlock() + q.pushWaitBufLocked(l) +} + +// Preconditions: +// * l.termiosMu must be held for reading. +// * q.mu must be locked. +func (q *queue) pushWaitBufLocked(l *lineDiscipline) { + // Remove bytes from the wait buffer and move them to the read buffer. + n := q.transform(l, q, q.waitBuf.Bytes()) + q.waitBuf.Next(n) + + // If state changed, notify any waiters. + if n > 0 { + q.Notify(waiter.EventIn) + } +} |