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-rw-r--r--pkg/abi/linux/tty.go20
-rw-r--r--pkg/sentry/fs/tty/line_discipline.go55
-rw-r--r--test/syscalls/linux/pty.cc6
3 files changed, 42 insertions, 39 deletions
diff --git a/pkg/abi/linux/tty.go b/pkg/abi/linux/tty.go
index e6f7c5b2a..bff882d89 100644
--- a/pkg/abi/linux/tty.go
+++ b/pkg/abi/linux/tty.go
@@ -14,10 +14,6 @@
package linux
-import (
- "unicode/utf8"
-)
-
const (
// NumControlCharacters is the number of control characters in Termios.
NumControlCharacters = 19
@@ -104,11 +100,19 @@ func (t *KernelTermios) FromTermios(term Termios) {
}
// IsTerminating returns whether c is a line terminating character.
-func (t *KernelTermios) IsTerminating(c rune) bool {
+func (t *KernelTermios) IsTerminating(cBytes []byte) bool {
+ // All terminating characters are 1 byte.
+ if len(cBytes) != 1 {
+ return false
+ }
+ c := cBytes[0]
+
+ // Is this the user-set EOF character?
if t.IsEOF(c) {
return true
}
- switch byte(c) {
+
+ switch c {
case disabledChar:
return false
case '\n', t.ControlCharacters[VEOL]:
@@ -120,8 +124,8 @@ func (t *KernelTermios) IsTerminating(c rune) bool {
}
// IsEOF returns whether c is the EOF character.
-func (t *KernelTermios) IsEOF(c rune) bool {
- return utf8.RuneLen(c) == 1 && byte(c) == t.ControlCharacters[VEOF] && t.ControlCharacters[VEOF] != disabledChar
+func (t *KernelTermios) IsEOF(c byte) bool {
+ return c == t.ControlCharacters[VEOF] && t.ControlCharacters[VEOF] != disabledChar
}
// Input flags.
diff --git a/pkg/sentry/fs/tty/line_discipline.go b/pkg/sentry/fs/tty/line_discipline.go
index 31b6344f2..c4a364edb 100644
--- a/pkg/sentry/fs/tty/line_discipline.go
+++ b/pkg/sentry/fs/tty/line_discipline.go
@@ -280,10 +280,12 @@ func (*outputQueueTransformer) transform(l *lineDiscipline, q *queue, buf []byte
var ret int
for len(buf) > 0 {
- c, size := l.peekRune(buf)
+ size := l.peek(buf)
+ cBytes := append([]byte{}, buf[:size]...)
ret += size
buf = buf[size:]
- switch c {
+ // We're guaranteed that cBytes has at least one element.
+ switch cBytes[0] {
case '\n':
if l.termios.OEnabled(linux.ONLRET) {
l.column = 0
@@ -297,7 +299,7 @@ func (*outputQueueTransformer) transform(l *lineDiscipline, q *queue, buf []byte
continue
}
if l.termios.OEnabled(linux.OCRNL) {
- c = '\n'
+ cBytes[0] = '\n'
if l.termios.OEnabled(linux.ONLRET) {
l.column = 0
}
@@ -319,10 +321,7 @@ func (*outputQueueTransformer) transform(l *lineDiscipline, q *queue, buf []byte
default:
l.column++
}
- // The compiler optimizes this by growing readBuf without
- // creating the intermediate slice.
- q.readBuf = append(q.readBuf, make([]byte, size)...)
- utf8.EncodeRune(q.readBuf[len(q.readBuf)-size:], c)
+ q.readBuf = append(q.readBuf, cBytes...)
}
if len(q.readBuf) > 0 {
q.readable = true
@@ -358,8 +357,10 @@ func (*inputQueueTransformer) transform(l *lineDiscipline, q *queue, buf []byte)
var ret int
for len(buf) > 0 && len(q.readBuf) < canonMaxBytes {
- c, size := l.peekRune(buf)
- switch c {
+ 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:]
@@ -367,17 +368,17 @@ func (*inputQueueTransformer) transform(l *lineDiscipline, q *queue, buf []byte)
continue
}
if l.termios.IEnabled(linux.ICRNL) {
- c = '\n'
+ cBytes[0] = '\n'
}
case '\n':
if l.termios.IEnabled(linux.INLCR) {
- c = '\r'
+ cBytes[0] = '\r'
}
}
// In canonical mode, we discard non-terminating characters
// after the first 4095.
- if l.shouldDiscard(q, c) {
+ if l.shouldDiscard(q, cBytes) {
buf = buf[size:]
ret += size
continue
@@ -387,20 +388,16 @@ func (*inputQueueTransformer) transform(l *lineDiscipline, q *queue, buf []byte)
if len(q.readBuf)+size > maxBytes {
break
}
- cBytes := buf[:size]
buf = buf[size:]
ret += size
// If we get EOF, make the buffer available for reading.
- if l.termios.LEnabled(linux.ICANON) && l.termios.IsEOF(c) {
+ if l.termios.LEnabled(linux.ICANON) && l.termios.IsEOF(cBytes[0]) {
q.readable = true
break
}
- // The compiler optimizes this by growing readBuf without
- // creating the intermediate slice.
- q.readBuf = append(q.readBuf, make([]byte, size)...)
- utf8.EncodeRune(q.readBuf[len(q.readBuf)-size:], c)
+ q.readBuf = append(q.readBuf, cBytes...)
// Anything written to the readBuf will have to be echoed.
if l.termios.LEnabled(linux.ECHO) {
@@ -409,7 +406,7 @@ func (*inputQueueTransformer) transform(l *lineDiscipline, q *queue, buf []byte)
}
// If we finish a line, make it available for reading.
- if l.termios.LEnabled(linux.ICANON) && l.termios.IsTerminating(c) {
+ if l.termios.LEnabled(linux.ICANON) && l.termios.IsTerminating(cBytes) {
q.readable = true
break
}
@@ -430,21 +427,17 @@ func (*inputQueueTransformer) transform(l *lineDiscipline, q *queue, buf []byte)
// 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) && len(q.readBuf)+utf8.RuneLen(c) >= canonMaxBytes && !l.termios.IsTerminating(c)
+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)
}
-// peekRune returns the first rune from the byte array depending on whether
-// UTF8 is enabled.
-func (l *lineDiscipline) peekRune(b []byte) (rune, int) {
- var c rune
- var size int
+// 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) {
- c, size = utf8.DecodeRune(b)
- } else {
- c = rune(b[0])
- size = 1
+ _, size = utf8.DecodeRune(b)
}
- return c, size
+ return size
}
diff --git a/test/syscalls/linux/pty.cc b/test/syscalls/linux/pty.cc
index 253aa26ba..5b2dc9ccb 100644
--- a/test/syscalls/linux/pty.cc
+++ b/test/syscalls/linux/pty.cc
@@ -568,6 +568,12 @@ TEST_F(PtyTest, WriteSlaveToMaster) {
EXPECT_EQ(memcmp(buf, kExpected, sizeof(kExpected)), 0);
}
+TEST_F(PtyTest, WriteInvalidUTF8) {
+ char c = 0xff;
+ ASSERT_THAT(syscall(__NR_write, master_.get(), &c, sizeof(c)),
+ SyscallSucceedsWithValue(sizeof(c)));
+}
+
// Both the master and slave report the standard default termios settings.
//
// Note that TCGETS on the master actually redirects to the slave (see comment
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-01 04:28:46 +0000