From a8f148b8e4098eaeb80e1d704b64aab8aeb1294f Mon Sep 17 00:00:00 2001 From: Nicolas Lacasse Date: Tue, 25 Jun 2019 11:46:19 -0700 Subject: Use different Ctty FDs based on the go version. An upcoming change in Go 1.13 [1] changes the semantics of the SysProcAttr.Ctty field. Prior to the change, the FD must be an FD in the child process's FD table (aka "post-shuffle"). After the change, the FD must be an FD in the current process's FD table (aka "pre-shuffle"). To be compatible with both versions this CL introduces a new boolean "CttyFdIsPostShuffle" which indicates whether a pre- or post-shuffle FD should be provided. We use build tags to chose the correct one. 1: https://go-review.googlesource.com/c/go/+/178919/ PiperOrigin-RevId: 255015303 --- runsc/cmd/exec.go | 10 ++++++++++ runsc/console/BUILD | 6 +++++- runsc/console/ctty_1_12.go | 24 ++++++++++++++++++++++++ runsc/console/ctty_1_13.go | 24 ++++++++++++++++++++++++ runsc/sandbox/sandbox.go | 13 +++++++++---- 5 files changed, 72 insertions(+), 5 deletions(-) create mode 100644 runsc/console/ctty_1_12.go create mode 100644 runsc/console/ctty_1_13.go diff --git a/runsc/cmd/exec.go b/runsc/cmd/exec.go index 7adc23a77..5a823e89a 100644 --- a/runsc/cmd/exec.go +++ b/runsc/cmd/exec.go @@ -237,6 +237,16 @@ func (ex *Exec) execChildAndWait(waitStatus *syscall.WaitStatus) subcommands.Exi Setctty: true, 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. 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 2d71cd371..b7d8f32ca 100644 --- a/runsc/console/BUILD +++ b/runsc/console/BUILD @@ -4,7 +4,11 @@ package(licenses = ["notice"]) go_library( name = "console", - srcs = ["console.go"], + srcs = [ + "console.go", + "ctty_1_12.go", + "ctty_1_13.go", + ], importpath = "gvisor.dev/gvisor/runsc/console", visibility = [ "//runsc:__subpackages__", diff --git a/runsc/console/ctty_1_12.go b/runsc/console/ctty_1_12.go new file mode 100644 index 000000000..6e7a314a3 --- /dev/null +++ b/runsc/console/ctty_1_12.go @@ -0,0 +1,24 @@ +// 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 new file mode 100644 index 000000000..785d720e1 --- /dev/null +++ b/runsc/console/ctty_1_13.go @@ -0,0 +1,24 @@ +// 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 52a5dfd77..1591052cd 100644 --- a/runsc/sandbox/sandbox.go +++ b/runsc/sandbox/sandbox.go @@ -437,11 +437,16 @@ func (s *Sandbox) createSandboxProcess(conf *boot.Config, args *Args, startSyncF defer tty.Close() // Set the TTY as a controlling TTY on the sandbox process. - // Note that the Ctty field must be the FD of the TTY in the - // *new* process, not this process. Since we are about to - // assign the TTY to nextFD, we can use that value here. cmd.SysProcAttr.Setctty = true - cmd.SysProcAttr.Ctty = nextFD + 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 + } // Pass the tty as all stdio fds to sandbox. for i := 0; i < 3; i++ { -- cgit v1.2.3