k3s/pkg/rootless/rootless.go

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// +build !windows
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package rootless
import (
"io/ioutil"
"net"
"os"
"os/exec"
"path/filepath"
"strings"
"github.com/pkg/errors"
"github.com/rootless-containers/rootlesskit/pkg/child"
"github.com/rootless-containers/rootlesskit/pkg/copyup/tmpfssymlink"
"github.com/rootless-containers/rootlesskit/pkg/network/slirp4netns"
"github.com/rootless-containers/rootlesskit/pkg/parent"
portbuiltin "github.com/rootless-containers/rootlesskit/pkg/port/builtin"
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"github.com/sirupsen/logrus"
)
var (
pipeFD = "_K3S_ROOTLESS_FD"
childEnv = "_K3S_ROOTLESS_SOCK"
Sock = ""
)
func Rootless(stateDir string) error {
defer func() {
os.Unsetenv(pipeFD)
os.Unsetenv(childEnv)
}()
hasFD := os.Getenv(pipeFD) != ""
hasChildEnv := os.Getenv(childEnv) != ""
if hasFD {
logrus.Debug("Running rootless child")
childOpt, err := createChildOpt()
if err != nil {
logrus.Fatal(err)
}
if err := child.Child(*childOpt); err != nil {
logrus.Fatalf("child died: %v", err)
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}
}
if hasChildEnv {
Sock = os.Getenv(childEnv)
logrus.Debug("Running rootless process")
return setupMounts(stateDir)
}
logrus.Debug("Running rootless parent")
parentOpt, err := createParentOpt(filepath.Join(stateDir, "rootless"))
if err != nil {
logrus.Fatal(err)
}
os.Setenv(childEnv, filepath.Join(parentOpt.StateDir, parent.StateFileAPISock))
if err := parent.Parent(*parentOpt); err != nil {
logrus.Fatal(err)
}
os.Exit(0)
return nil
}
func parseCIDR(s string) (*net.IPNet, error) {
if s == "" {
return nil, nil
}
ip, ipnet, err := net.ParseCIDR(s)
if err != nil {
return nil, err
}
if !ip.Equal(ipnet.IP) {
return nil, errors.Errorf("cidr must be like 10.0.2.0/24, not like 10.0.2.100/24")
}
return ipnet, nil
}
func createParentOpt(stateDir string) (*parent.Opt, error) {
if err := os.MkdirAll(stateDir, 0755); err != nil {
return nil, errors.Wrapf(err, "failed to mkdir %s", stateDir)
}
stateDir, err := ioutil.TempDir("", "rootless")
if err != nil {
return nil, err
}
opt := &parent.Opt{
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StateDir: stateDir,
CreatePIDNS: true,
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}
mtu := 0
ipnet, err := parseCIDR("10.41.0.0/16")
if err != nil {
return nil, err
}
disableHostLoopback := true
binary := "slirp4netns"
if _, err := exec.LookPath(binary); err != nil {
return nil, err
}
debugWriter := &logrusDebugWriter{}
opt.NetworkDriver, err = slirp4netns.NewParentDriver(debugWriter, binary, mtu, ipnet, disableHostLoopback, "", false, false)
if err != nil {
return nil, err
}
opt.PortDriver, err = portbuiltin.NewParentDriver(debugWriter, stateDir)
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if err != nil {
return nil, err
}
opt.PipeFDEnvKey = pipeFD
return opt, nil
}
type logrusDebugWriter struct {
}
func (w *logrusDebugWriter) Write(p []byte) (int, error) {
s := strings.TrimSuffix(string(p), "\n")
logrus.Debug(s)
return len(p), nil
}
func createChildOpt() (*child.Opt, error) {
opt := &child.Opt{}
opt.TargetCmd = os.Args
opt.PipeFDEnvKey = pipeFD
opt.NetworkDriver = slirp4netns.NewChildDriver()
opt.PortDriver = portbuiltin.NewChildDriver(&logrusDebugWriter{})
opt.CopyUpDirs = []string{"/etc", "/run", "/var/lib"}
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opt.CopyUpDriver = tmpfssymlink.NewChildDriver()
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opt.MountProcfs = true
opt.Reaper = true
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return opt, nil
}