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[release-1.21] oci: properly handle tty on execsync #5121

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Merged
openshift-merge-robot merged 1 commit into from
Jul 23, 2021
Merged

[release-1.21] oci: properly handle tty on execsync #5121

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121 changes: 65 additions & 56 deletions internal/oci/runtime_oci.go
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Original file line number Diff line number Diff line change
Expand Up @@ -262,54 +262,8 @@ func (r *runtimeOCI) ExecContainer(ctx context.Context, c *Container, cmd []stri
return err
}
defer os.RemoveAll(processFile)

execCmd := r.constructExecCommand(ctx, c, processFile, "")
var cmdErr, copyError error
if tty {
cmdErr = ttyCmd(execCmd, stdin, stdout, resize)
} else {
var r, w *os.File
if stdin != nil {
// Use an os.Pipe here as it returns true *os.File objects.
// This way, if you run 'kubectl exec <pod> -i bash' (no tty) and type 'exit',
// the call below to execCmd.Run() can unblock because its Stdin is the read half
// of the pipe.
r, w, err = os.Pipe()
if err != nil {
return err
}
execCmd.Stdin = r
go func() {
_, copyError = pools.Copy(w, stdin)
w.Close()
}()
}

if stdout != nil {
execCmd.Stdout = stdout
}

if stderr != nil {
execCmd.Stderr = stderr
}

if err := execCmd.Start(); err != nil {
return err
}

// The read side of the pipe should be closed after the container process has been started.
if r != nil {
if err := r.Close(); err != nil {
return err
}
}

cmdErr = execCmd.Wait()
}

if copyError != nil {
return copyError
}
cmdErr := r.executeExec(execCmd, stdin, stdout, stderr, tty, resize)
if exitErr, ok := cmdErr.(*exec.ExitError); ok {
return &utilexec.ExitErrorWrapper{ExitError: exitErr}
}
Expand Down Expand Up @@ -339,32 +293,28 @@ func (r *runtimeOCI) ExecSyncContainer(ctx context.Context, c *Container, comman
cmd := r.constructExecCommand(ctx, c, processFile, pidFile)
cmd.SysProcAttr = sysProcAttrPlatform()

var stdoutBuf, stderrBuf bytes.Buffer
cmd.Stdout = &stdoutBuf
cmd.Stderr = &stderrBuf
stdoutBuf := nopWriteCloser{&bytes.Buffer{}}
stderrBuf := nopWriteCloser{&bytes.Buffer{}}
resize := make(chan remotecommand.TerminalSize)

pidFileCreatedDone := make(chan struct{}, 1)
pidFileCreatedCh, err := WatchForFile(pidFile, pidFileCreatedDone, notify.InModify, notify.InMovedTo)
if err != nil {
return nil, errors.Wrapf(err, "failed to watch %s", pidFile)
}

doneErr := cmd.Start()
if doneErr != nil {
return nil, err
}

// wait till the command is done
done := make(chan error, 1)
go func() {
done <- cmd.Wait()
done <- r.executeExec(cmd, nil, stdoutBuf, stderrBuf, c.terminal, resize)
close(done)
}()

// First, wait for the pid file to be created.
// When it is, the timer begins for the exec process.
// If the command fails before that happens, however,
// that needs to be caught.
var doneErr error
select {
case <-pidFileCreatedCh:
case doneErr = <-done:
Expand Down Expand Up @@ -416,6 +366,65 @@ func (r *runtimeOCI) ExecSyncContainer(ctx context.Context, c *Container, comman
}, nil
}

func (r *runtimeOCI) executeExec(execCmd *exec.Cmd, stdin io.Reader, stdout, stderr io.WriteCloser, tty bool, resize <-chan remotecommand.TerminalSize) error {
var cmdErr, copyError error
if tty {
return ttyCmd(execCmd, stdin, stdout, resize)
}
var rd, w *os.File
var err error
if stdin != nil {
// Use an os.Pipe here as it returns true *os.File objects.
// This way, if you run 'kubectl exec <pod> -i bash' (no tty) and type 'exit',
// the call below to execCmd.Run() can unblock because its Stdin is the read half
// of the pipe.
rd, w, err = os.Pipe()
if err != nil {
return err
}
execCmd.Stdin = rd
go func() {
_, copyError = pools.Copy(w, stdin)
w.Close()
}()
}

if stdout != nil {
execCmd.Stdout = stdout
}

if stderr != nil {
execCmd.Stderr = stderr
}

if err := execCmd.Start(); err != nil {
return err
}

// The read side of the pipe should be closed after the container process has been started.
if rd != nil {
if err := rd.Close(); err != nil {
return err
}
}

cmdErr = execCmd.Wait()

if copyError != nil {
return copyError
}
return cmdErr
}

// Needed because https://github.com/golang/go/issues/22823 was denied
type nopWriteCloser struct {
*bytes.Buffer
}

func (nopWriteCloser) Close() error {
return nil
}

func (r *runtimeOCI) constructExecCommand(ctx context.Context, c *Container, processFile, pidFile string) *exec.Cmd {
args := []string{rootFlag, r.root, "exec"}
if pidFile != "" {
Expand Down
9 changes: 9 additions & 0 deletions test/ctr.bats
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Original file line number Diff line number Diff line change
Expand Up @@ -467,6 +467,15 @@ function wait_until_exit() {
crictl rm -f "$ctr_id"
}

@test "ctr execsync should succeed if container has a terminal" {
start_crio

jq ' .tty = true' "$TESTDATA"/container_sleep.json > "$newconfig"

ctr_id=$(crictl run "$newconfig" "$TESTDATA"/sandbox_config.json)
crictl exec --sync "$ctr_id" /bin/sh -c "[[ -t 1 ]]"
}

@test "ctr device add" {
# In an user namespace we can only bind mount devices from the host, not mknod
# https://github.com/opencontainers/runc/blob/master/libcontainer/rootfs_linux.go#L480-L481
Expand Down