From 67e2f227aac49129936efc640a6c47a0978b187d Mon Sep 17 00:00:00 2001 From: Nicolas Lacasse Date: Wed, 26 Jun 2019 11:26:18 -0700 Subject: [PATCH] Always set SysProcAttr.Ctty to an FD in the child's FD table. Go was going to change the behavior of SysProcAttr.Ctty such that it must be an FD in the *parent* FD table: https://go-review.googlesource.com/c/go/+/178919/ However, after some debate, it was decided that this change was too backwards-incompatible, and so it was reverted. https://github.com/golang/go/issues/29458 The behavior going forward is unchanged: the Ctty FD must be an FD in the *child* FD table. PiperOrigin-RevId: 255228476 --- runsc/cmd/exec.go | 16 +++++----------- runsc/console/BUILD | 2 -- runsc/console/ctty_1_12.go | 24 ------------------------ runsc/console/ctty_1_13.go | 24 ------------------------ runsc/sandbox/sandbox.go | 13 ++++--------- 5 files changed, 9 insertions(+), 70 deletions(-) delete mode 100644 runsc/console/ctty_1_12.go delete mode 100644 runsc/console/ctty_1_13.go diff --git a/runsc/cmd/exec.go b/runsc/cmd/exec.go index 5a823e89a..e817eff77 100644 --- a/runsc/cmd/exec.go +++ b/runsc/cmd/exec.go @@ -235,18 +235,12 @@ func (ex *Exec) execChildAndWait(waitStatus *syscall.WaitStatus) subcommands.Exi cmd.SysProcAttr = &syscall.SysProcAttr{ Setsid: true, Setctty: true, - Ctty: int(tty.Fd()), + // The Ctty FD must be the FD in the child process's FD + // table. Since we set cmd.Stdin/Stdout/Stderr to the + // tty FD, we can use any of 0, 1, or 2 here. + // See https://github.com/golang/go/issues/29458. + Ctty: 0, } - // TODO(b/133868570): Delete this check once Go 1.12 is no - // longer supported. - if console.CttyFdIsPostShuffle { - // In go1.12 and before, the Ctty FD must be the FD in - // the child process's FD table. Since we set - // cmd.Stdin/Stdout/Stderr to the tty FD, we can use - // any of 0, 1, or 2 here. - cmd.SysProcAttr.Ctty = 0 - } - } if err := cmd.Start(); err != nil { diff --git a/runsc/console/BUILD b/runsc/console/BUILD index b7d8f32ca..e623c1a0f 100644 --- a/runsc/console/BUILD +++ b/runsc/console/BUILD @@ -6,8 +6,6 @@ go_library( name = "console", srcs = [ "console.go", - "ctty_1_12.go", - "ctty_1_13.go", ], importpath = "gvisor.dev/gvisor/runsc/console", visibility = [ diff --git a/runsc/console/ctty_1_12.go b/runsc/console/ctty_1_12.go deleted file mode 100644 index 6e7a314a3..000000000 --- a/runsc/console/ctty_1_12.go +++ /dev/null @@ -1,24 +0,0 @@ -// Copyright 2019 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. - -// +build go1.12 -// +build !go1.13 - -// TODO(b/133868570): Delete once Go 1.12 is no longer supported. - -package console - -// CttyFdIsPostShuffle indicates that in go1.12 and earlier, the -// SysProcAttr.Ctty FD is determined "pre-shuffle" (not "post-shuffle"). -var CttyFdIsPostShuffle = false diff --git a/runsc/console/ctty_1_13.go b/runsc/console/ctty_1_13.go deleted file mode 100644 index 785d720e1..000000000 --- a/runsc/console/ctty_1_13.go +++ /dev/null @@ -1,24 +0,0 @@ -// Copyright 2019 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. - -// +build go1.13 -// +build !go1.14 - -// TODO(b/133868570): Delete once Go 1.12 is no longer supported. - -package console - -// CttyFdIsPostShuffle indicates that in go1.13 and later, the SysProcAttr.Ctty -// FD is determined "post-shuffle". -var CttyFdIsPostShuffle = true diff --git a/runsc/sandbox/sandbox.go b/runsc/sandbox/sandbox.go index 1591052cd..6bebf0737 100644 --- a/runsc/sandbox/sandbox.go +++ b/runsc/sandbox/sandbox.go @@ -438,15 +438,10 @@ func (s *Sandbox) createSandboxProcess(conf *boot.Config, args *Args, startSyncF // Set the TTY as a controlling TTY on the sandbox process. cmd.SysProcAttr.Setctty = true - cmd.SysProcAttr.Ctty = int(tty.Fd()) - // TODO(b/133868570): Delete this check once Go 1.12 is no - // longer supported. - if console.CttyFdIsPostShuffle { - // In go1.12 and before, the Ctty FD must be the FD in - // the child process's FD table, which will be "nextFD" - // in this case. - cmd.SysProcAttr.Ctty = nextFD - } + // The Ctty FD must be the FD in the child process's FD table, + // which will be nextFD in this case. + // See https://github.com/golang/go/issues/29458. + cmd.SysProcAttr.Ctty = nextFD // Pass the tty as all stdio fds to sandbox. for i := 0; i < 3; i++ {