mirror of
https://github.com/gitpod-io/gitpod.git
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110 lines
2.7 KiB
Go
110 lines
2.7 KiB
Go
// Copyright (c) 2021 Gitpod GmbH. All rights reserved.
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// Licensed under the GNU Affero General Public License (AGPL).
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// See License.AGPL.txt in the project root for license information.
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//go:build linux
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// +build linux
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package nsenter
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import (
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"fmt"
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"os"
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"os/exec"
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"strconv"
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"golang.org/x/sys/unix"
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"golang.org/x/xerrors"
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)
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type Namespace int
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const (
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// NamespaceMount refers to the mount namespace
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NamespaceMount = iota
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// NamespaceNet refers to the network namespace
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NamespaceNet
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// NamespaceNet refers to the network namespace
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NamespacePID
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)
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// Run executes a workspacekit handler in a namespace.
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// Use preflight to check libseccomp.NotifIDValid().
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func Run(pid int, args []string, addFD []*os.File, enterNamespace ...Namespace) error {
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nss := []struct {
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Env string
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Source string
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Flags int
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NS Namespace
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}{
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{"_LIBNSENTER_ROOTFD", fmt.Sprintf("/proc/%d/root", pid), unix.O_PATH, -1},
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{"_LIBNSENTER_CWDFD", fmt.Sprintf("/proc/%d/cwd", pid), unix.O_PATH, -1},
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{"_LIBNSENTER_MNTNSFD", fmt.Sprintf("/proc/%d/ns/mnt", pid), os.O_RDONLY, NamespaceMount},
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{"_LIBNSENTER_NETNSFD", fmt.Sprintf("/proc/%d/ns/net", pid), os.O_RDONLY, NamespaceNet},
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{"_LIBNSENTER_PIDNSFD", fmt.Sprintf("/proc/%d/ns/pid", pid), os.O_RDONLY, NamespacePID},
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}
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stdioFdCount := 3
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cmd := exec.Command("/proc/self/exe", append([]string{"handler"}, args...)...)
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cmd.ExtraFiles = append(cmd.ExtraFiles, addFD...)
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cmd.Env = os.Environ()
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cmd.Env = append(cmd.Env, "_LIBNSENTER_INIT=1")
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for _, ns := range nss {
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var enter bool
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if ns.NS == -1 {
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enter = true
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} else {
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for _, s := range enterNamespace {
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if ns.NS == s {
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enter = true
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break
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}
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}
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}
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if !enter {
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continue
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}
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f, err := os.OpenFile(ns.Source, ns.Flags, 0)
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if err != nil {
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return xerrors.Errorf("cannot open %s: %w", ns.Source, err)
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}
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defer f.Close()
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cmd.Env = append(cmd.Env, fmt.Sprintf("%s=%d", ns.Env, stdioFdCount+len(cmd.ExtraFiles)))
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cmd.ExtraFiles = append(cmd.ExtraFiles, f)
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}
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cmd.Stdout = os.Stdout
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cmd.Stderr = os.Stderr
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cmd.Stdin = os.Stdin
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err := cmd.Run()
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if err != nil {
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return xerrors.Errorf("cannot run handler: %w", err)
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}
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return nil
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}
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// Mount executes mount in the mount namespace of PID
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func Mount(pid int, source, target string, fstype string, flags int, data string) error {
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args := []string{"mount",
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"--source", source,
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"--target", target,
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"--flags", strconv.Itoa(flags),
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}
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if fstype != "" {
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args = append(args, "--fstype", fstype)
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}
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if data != "" {
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args = append(args, "--data", data)
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}
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return Run(pid, args, nil, NamespaceMount)
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}
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func MoveMount(pid int, fromFD *os.File, target string) error {
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args := []string{"move-mount",
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"--fd", "3",
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"--dest", target,
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}
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return Run(pid, args, []*os.File{fromFD}, NamespaceMount)
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}
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