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-rw-r--r--pkg/sentry/fs/tty/line_discipline.go135
-rw-r--r--pkg/sentry/fs/tty/terminal.go4
-rw-r--r--pkg/sentry/fs/tty/tty_test.go2
3 files changed, 99 insertions, 42 deletions
diff --git a/pkg/sentry/fs/tty/line_discipline.go b/pkg/sentry/fs/tty/line_discipline.go
index bdc4f5b92..a4012135c 100644
--- a/pkg/sentry/fs/tty/line_discipline.go
+++ b/pkg/sentry/fs/tty/line_discipline.go
@@ -38,8 +38,20 @@ 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
@@ -62,6 +74,11 @@ type queue struct {
// 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.
@@ -142,9 +159,9 @@ func (q *queue) readableSize(ctx context.Context, io usermem.IO, args arch.Sysca
// (outputQueueRead) +--------------+ (outputQueueWrite)
//
// Lock order:
-// inMu
-// outMu
-// termiosMu
+// termiosMu
+// inMu
+// outMu
type lineDiscipline struct {
// inMu protects inQueue.
inMu sync.Mutex `state:"nosave"`
@@ -159,7 +176,7 @@ type lineDiscipline struct {
outQueue queue
// termiosMu protects termios.
- termiosMu sync.Mutex `state:"nosave"`
+ termiosMu sync.RWMutex `state:"nosave"`
// termios is the terminal configuration used by the lineDiscipline.
termios linux.KernelTermios
@@ -169,10 +186,17 @@ type lineDiscipline struct {
column int
}
+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.Lock()
- defer l.termiosMu.Unlock()
+ 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{
@@ -183,10 +207,10 @@ func (l *lineDiscipline) getTermios(ctx context.Context, io usermem.IO, args arc
// setTermios sets a linux.Termios for the tty.
func (l *lineDiscipline) setTermios(ctx context.Context, io usermem.IO, args arch.SyscallArguments) (uintptr, error) {
- l.inMu.Lock()
- defer l.inMu.Unlock()
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
@@ -199,7 +223,7 @@ 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, transformInput)
+ l.pushWaitBuf(&l.inQueue)
}
return 0, err
@@ -216,12 +240,12 @@ 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()
- l.termiosMu.Lock()
- defer l.termiosMu.Unlock()
return l.outQueue.writeReadiness(&l.termios) | l.inQueue.readReadiness(&l.termios)
}
@@ -232,15 +256,19 @@ func (l *lineDiscipline) inputQueueReadSize(ctx context.Context, io usermem.IO,
}
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, transformInput)
+ return l.queueRead(ctx, dst, &l.inQueue)
}
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, transformInput)
+ return l.queueWrite(ctx, src, &l.inQueue)
}
func (l *lineDiscipline) outputQueueReadSize(ctx context.Context, io usermem.IO, args arch.SyscallArguments) error {
@@ -250,21 +278,27 @@ func (l *lineDiscipline) outputQueueReadSize(ctx context.Context, io usermem.IO,
}
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, transformOutput)
+ return l.queueRead(ctx, dst, &l.outQueue)
}
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, transformOutput)
+ return l.queueWrite(ctx, src, &l.outQueue)
}
// queueRead reads from q to userspace.
//
-// Preconditions: q's lock must be held.
-func (l *lineDiscipline) queueRead(ctx context.Context, dst usermem.IOSequence, q *queue, f transform) (int64, error) {
+// 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
}
@@ -290,9 +324,7 @@ func (l *lineDiscipline) queueRead(ctx context.Context, dst usermem.IOSequence,
}
// Move data from the queue's wait buffer to its read buffer.
- l.termiosMu.Lock()
- defer l.termiosMu.Unlock()
- l.pushWaitBuf(q, f)
+ l.pushWaitBuf(q)
// If state changed, notify any waiters. If nothing was available to
// read, let the caller know we could block.
@@ -304,11 +336,12 @@ func (l *lineDiscipline) queueRead(ctx context.Context, dst usermem.IOSequence,
return int64(n), nil
}
-// queueWrite writes to q from userspace. f is the function used to perform
-// processing on data being written and write it to the read buffer.
+// queueWrite writes to q from userspace.
//
-// Precondition: q's lock must be held.
-func (l *lineDiscipline) queueWrite(ctx context.Context, src usermem.IOSequence, q *queue, f transform) (int64, error) {
+// 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())
@@ -317,11 +350,17 @@ func (l *lineDiscipline) queueWrite(ctx context.Context, src usermem.IOSequence,
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.
- l.termiosMu.Lock()
- defer l.termiosMu.Unlock()
- n = f(l, q, b)
+ n := q.transform(l, q, b)
// Write remaining data to the wait buffer.
nWaiting, _ := q.waitBuf.Write(b[n:])
@@ -338,10 +377,12 @@ func (l *lineDiscipline) queueWrite(ctx context.Context, src usermem.IOSequence,
// pushWaitBuf fills the queue's read buffer with data from the wait buffer.
//
-// Precondition: l.inMu and l.termiosMu must be held.
-func (l *lineDiscipline) pushWaitBuf(q *queue, f transform) {
+// 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 := f(l, q, q.waitBuf.Bytes())
+ n := q.transform(l, q, q.waitBuf.Bytes())
q.waitBuf.Next(n)
// If state changed, notify any waiters.
@@ -350,14 +391,16 @@ func (l *lineDiscipline) pushWaitBuf(q *queue, f transform) {
}
}
-// transform functions require the passed in lineDiscipline's mutex to be held.
-type transform func(*lineDiscipline, *queue, []byte) int
+// outputQueueTransformer implements transformer.
+type outputQueueTransformer struct{}
-// transformOutput does output processing for one end of the pty. See
+// transform does output processing for one end of the pty. See
// drivers/tty/n_tty.c:do_output_char for an analogous kernel function.
//
-// Precondition: l.termiosMu and q's mutex must be held.
-func transformOutput(l *lineDiscipline, q *queue, buf []byte) int {
+// Precondition:
+// * l.termiosMu must be held for reading.
+// * q's mutex 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.
@@ -418,13 +461,18 @@ func transformOutput(l *lineDiscipline, q *queue, buf []byte) int {
return ret
}
-// transformInput does input processing for one end of the pty. Characters read
-// are transformed according to flags set in the termios struct. See
+// inputQueueTransformer implements transformer.
+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.
//
-// Precondition: l.termiosMu and q's mutex must be held.
-func transformInput(l *lineDiscipline, q *queue, buf []byte) int {
+// Precondition:
+// * l.termiosMu must be held for reading.
+// * q's mutex 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 {
@@ -467,6 +515,7 @@ func transformInput(l *lineDiscipline, q *queue, buf []byte) int {
if q.readBuf.Len()+size > maxBytes {
break
}
+ cBytes := buf[:size]
buf = buf[size:]
ret += size
@@ -477,6 +526,14 @@ func transformInput(l *lineDiscipline, q *queue, buf []byte) int {
}
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()
+ }
// If we finish a line, make it available for reading.
if l.termios.LEnabled(linux.ICANON) && l.termios.IsTerminating(c) {
diff --git a/pkg/sentry/fs/tty/terminal.go b/pkg/sentry/fs/tty/terminal.go
index 6ae713a32..fa5b00409 100644
--- a/pkg/sentry/fs/tty/terminal.go
+++ b/pkg/sentry/fs/tty/terminal.go
@@ -31,7 +31,7 @@ type Terminal struct {
d *dirInodeOperations
// ld is the line discipline of the terminal.
- ld lineDiscipline
+ ld *lineDiscipline
}
func newTerminal(ctx context.Context, d *dirInodeOperations, n uint32) *Terminal {
@@ -39,6 +39,6 @@ func newTerminal(ctx context.Context, d *dirInodeOperations, n uint32) *Terminal
return &Terminal{
d: d,
n: n,
- ld: lineDiscipline{termios: termios},
+ ld: newLineDiscipline(termios),
}
}
diff --git a/pkg/sentry/fs/tty/tty_test.go b/pkg/sentry/fs/tty/tty_test.go
index 0c7560ed7..32e1b1556 100644
--- a/pkg/sentry/fs/tty/tty_test.go
+++ b/pkg/sentry/fs/tty/tty_test.go
@@ -23,7 +23,7 @@ import (
)
func TestSimpleMasterToSlave(t *testing.T) {
- ld := lineDiscipline{termios: linux.DefaultSlaveTermios}
+ ld := newLineDiscipline(linux.DefaultSlaveTermios)
ctx := contexttest.Context(t)
inBytes := []byte("hello, tty\n")
src := usermem.BytesIOSequence(inBytes)
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-24 23:02:06 +0000