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chore: remove specific go version code

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Now that we have 1.24.x as go min version, I think
we can remove this go code specific to a lower
version.

Signed-off-by: Jin Dong <djdongjin95@gmail.com>
This commit is contained in:
Jin Dong
2025-05-14 09:40:17 -04:00
parent 2af24b5629
commit 734d52c39c
3 changed files with 20 additions and 123 deletions
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34
core/mount/mount_idmapped_utils_linux.go
View File

@@ -1,5 +1,3 @@
//go:build go1.23 && linux
/*
Copyright The containerd Authors.
@@ -29,17 +27,8 @@ import (
)
// getUsernsFD returns pinnable user namespace's file descriptor.
//
// NOTE: The GO runtime uses pidfd to handle subprocess since go1.23. However,
// it has double close issue tracked by [1]. We can't use pidfd directly and
// the GO runtime doesn't export interface to show if it's using pidfd or not.
// So, we call `sys.SupportsPidFD` first and then use `os.Process` directly.
//
// [1]: https://github.com/golang/go/issues/68984
func getUsernsFD(uidMaps, gidMaps []syscall.SysProcIDMap) (_ *os.File, retErr error) {
if !sys.SupportsPidFD() {
return nil, fmt.Errorf("failed to prevent pid reused issue because pidfd isn't supported")
}
var pidfd int
proc, err := os.StartProcess("/proc/self/exe", []string{"containerd[getUsernsFD]"}, &os.ProcAttr{
Sys: &syscall.SysProcAttr{
@@ -50,15 +39,26 @@ func getUsernsFD(uidMaps, gidMaps []syscall.SysProcIDMap) (_ *os.File, retErr er
// be in PTRACE_TRACEME mode before performing execve.
Ptrace: true,
Pdeathsig: syscall.SIGKILL,
PidFD: &pidfd,
},
})
if err != nil {
return nil, fmt.Errorf("failed to start noop process for unshare: %w", err)
}
defer func() {
if pidfd == -1 || !sys.SupportsPidFD() {
proc.Kill()
proc.Wait()
return nil, fmt.Errorf("failed to prevent pid reused issue because pidfd isn't supported")
}
pidFD := os.NewFile(uintptr(pidfd), "pidfd")
defer func() {
unix.PidfdSendSignal(int(pidFD.Fd()), unix.SIGKILL, nil, 0)
pidfdWaitid(pidFD)
pidFD.Close()
}()
// NOTE:
@@ -78,8 +78,14 @@ func getUsernsFD(uidMaps, gidMaps []syscall.SysProcIDMap) (_ *os.File, retErr er
// Ensure the child process is still alive. If the err is ESRCH, we
// should return error because we can't guarantee the usernsFD and
// u[g]idmapFile are valid. It's safe to return error and retry.
if err := proc.Signal(syscall.Signal(0)); err != nil {
if err := unix.PidfdSendSignal(int(pidFD.Fd()), 0, nil, 0); err != nil {
return nil, fmt.Errorf("failed to ensure child process is alive: %w", err)
}
return usernsFD, nil
}
func pidfdWaitid(pidFD *os.File) error {
return sys.IgnoringEINTR(func() error {
return unix.Waitid(unix.P_PIDFD, int(pidFD.Fd()), nil, unix.WEXITED, nil)
})
}

93
core/mount/mount_idmapped_utils_linux_go122.go
View File

@@ -1,93 +0,0 @@
//go:build !go1.23 && linux
/*
Copyright The containerd 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.
*/
package mount
import (
"fmt"
"os"
"syscall"
"github.com/containerd/containerd/v2/pkg/sys"
"golang.org/x/sys/unix"
)
// getUsernsFD returns pinnable user namespace's file descriptor.
func getUsernsFD(uidMaps, gidMaps []syscall.SysProcIDMap) (_ *os.File, retErr error) {
var pidfd int
proc, err := os.StartProcess("/proc/self/exe", []string{"containerd[getUsernsFD]"}, &os.ProcAttr{
Sys: &syscall.SysProcAttr{
Cloneflags: unix.CLONE_NEWUSER,
UidMappings: uidMaps,
GidMappings: gidMaps,
// NOTE: It's reexec but it's not heavy because subprocess
// be in PTRACE_TRACEME mode before performing execve.
Ptrace: true,
Pdeathsig: syscall.SIGKILL,
PidFD: &pidfd,
},
})
if err != nil {
return nil, fmt.Errorf("failed to start noop process for unshare: %w", err)
}
if pidfd == -1 || !sys.SupportsPidFD() {
proc.Kill()
proc.Wait()
return nil, fmt.Errorf("failed to prevent pid reused issue because pidfd isn't supported")
}
pidFD := os.NewFile(uintptr(pidfd), "pidfd")
defer func() {
unix.PidfdSendSignal(int(pidFD.Fd()), unix.SIGKILL, nil, 0)
pidfdWaitid(pidFD)
pidFD.Close()
}()
// NOTE:
//
// The usernsFD will hold the userns reference in kernel. Even if the
// child process is reaped, the usernsFD is still valid.
usernsFD, err := os.Open(fmt.Sprintf("/proc/%d/ns/user", proc.Pid))
if err != nil {
return nil, fmt.Errorf("failed to get userns file descriptor for /proc/%d/user/ns: %w", proc.Pid, err)
}
defer func() {
if retErr != nil {
usernsFD.Close()
}
}()
// Ensure the child process is still alive. If the err is ESRCH, we
// should return error because we can't guarantee the usernsFD and
// u[g]idmapFile are valid. It's safe to return error and retry.
if err := unix.PidfdSendSignal(int(pidFD.Fd()), 0, nil, 0); err != nil {
return nil, fmt.Errorf("failed to ensure child process is alive: %w", err)
}
return usernsFD, nil
}
func pidfdWaitid(pidFD *os.File) error {
return sys.IgnoringEINTR(func() error {
return unix.Waitid(unix.P_PIDFD, int(pidFD.Fd()), nil, unix.WEXITED, nil)
})
}

16
pkg/sys/unshare_linux.go
View File

@@ -20,7 +20,6 @@ import (
"errors"
"fmt"
"os"
"runtime"
"strconv"
"strings"
"syscall"
@@ -71,21 +70,6 @@ func UnshareAfterEnterUserns(uidMap, gidMap string, unshareFlags uintptr, f func
return fmt.Errorf("kernel doesn't support CLONE_PIDFD")
}
// Since go1.23.{0,1} has double close issue, we should dup it before using it.
//
// References:
// - https://github.com/golang/go/issues/68984
// - https://github.com/golang/go/milestone/371
if goVer := runtime.Version(); goVer == "go1.23.0" || goVer == "go1.23.1" {
dupPidfd, err := unix.FcntlInt(uintptr(pidfd), syscall.F_DUPFD_CLOEXEC, 0)
if err != nil {
proc.Kill()
proc.Wait()
return fmt.Errorf("failed to dupfd: %w", err)
}
pidfd = dupPidfd
}
defer func() {
derr := unix.PidfdSendSignal(pidfd, unix.SIGKILL, nil, 0)
if derr != nil {