151 lines
3.2 KiB
Go
151 lines
3.2 KiB
Go
// +build linux
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package system
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import (
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"os"
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"os/exec"
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"sync"
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"unsafe"
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"github.com/opencontainers/runc/libcontainer/user"
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"golang.org/x/sys/unix"
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)
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type ParentDeathSignal int
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func (p ParentDeathSignal) Restore() error {
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if p == 0 {
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return nil
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}
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current, err := GetParentDeathSignal()
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if err != nil {
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return err
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}
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if p == current {
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return nil
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}
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return p.Set()
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}
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func (p ParentDeathSignal) Set() error {
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return SetParentDeathSignal(uintptr(p))
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}
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func Execv(cmd string, args []string, env []string) error {
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name, err := exec.LookPath(cmd)
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if err != nil {
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return err
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}
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return unix.Exec(name, args, env)
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}
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func Prlimit(pid, resource int, limit unix.Rlimit) error {
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_, _, err := unix.RawSyscall6(unix.SYS_PRLIMIT64, uintptr(pid), uintptr(resource), uintptr(unsafe.Pointer(&limit)), uintptr(unsafe.Pointer(&limit)), 0, 0)
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if err != 0 {
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return err
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}
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return nil
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}
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func SetParentDeathSignal(sig uintptr) error {
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if err := unix.Prctl(unix.PR_SET_PDEATHSIG, sig, 0, 0, 0); err != nil {
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return err
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}
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return nil
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}
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func GetParentDeathSignal() (ParentDeathSignal, error) {
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var sig int
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if err := unix.Prctl(unix.PR_GET_PDEATHSIG, uintptr(unsafe.Pointer(&sig)), 0, 0, 0); err != nil {
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return -1, err
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}
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return ParentDeathSignal(sig), nil
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}
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func SetKeepCaps() error {
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if err := unix.Prctl(unix.PR_SET_KEEPCAPS, 1, 0, 0, 0); err != nil {
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return err
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}
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return nil
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}
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func ClearKeepCaps() error {
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if err := unix.Prctl(unix.PR_SET_KEEPCAPS, 0, 0, 0, 0); err != nil {
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return err
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}
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return nil
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}
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func Setctty() error {
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if err := unix.IoctlSetInt(0, unix.TIOCSCTTY, 0); err != nil {
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return err
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}
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return nil
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}
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var (
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inUserNS bool
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nsOnce sync.Once
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)
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// RunningInUserNS detects whether we are currently running in a user namespace.
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// Originally copied from github.com/lxc/lxd/shared/util.go
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func RunningInUserNS() bool {
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nsOnce.Do(func() {
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uidmap, err := user.CurrentProcessUIDMap()
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if err != nil {
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// This kernel-provided file only exists if user namespaces are supported
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return
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}
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inUserNS = UIDMapInUserNS(uidmap)
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})
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return inUserNS
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}
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func UIDMapInUserNS(uidmap []user.IDMap) bool {
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/*
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* We assume we are in the initial user namespace if we have a full
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* range - 4294967295 uids starting at uid 0.
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*/
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if len(uidmap) == 1 && uidmap[0].ID == 0 && uidmap[0].ParentID == 0 && uidmap[0].Count == 4294967295 {
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return false
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}
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return true
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}
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// GetParentNSeuid returns the euid within the parent user namespace
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func GetParentNSeuid() int64 {
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euid := int64(os.Geteuid())
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uidmap, err := user.CurrentProcessUIDMap()
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if err != nil {
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// This kernel-provided file only exists if user namespaces are supported
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return euid
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}
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for _, um := range uidmap {
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if um.ID <= euid && euid <= um.ID+um.Count-1 {
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return um.ParentID + euid - um.ID
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}
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}
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return euid
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}
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// SetSubreaper sets the value i as the subreaper setting for the calling process
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func SetSubreaper(i int) error {
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return unix.Prctl(unix.PR_SET_CHILD_SUBREAPER, uintptr(i), 0, 0, 0)
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}
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// GetSubreaper returns the subreaper setting for the calling process
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func GetSubreaper() (int, error) {
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var i uintptr
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if err := unix.Prctl(unix.PR_GET_CHILD_SUBREAPER, uintptr(unsafe.Pointer(&i)), 0, 0, 0); err != nil {
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return -1, err
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}
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return int(i), nil
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}
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