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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,149 @@ | ||
| package libcontainer | ||
|
|
||
| import ( | ||
| "encoding/json" | ||
| "fmt" | ||
| "io" | ||
| "os" | ||
|
|
||
| "github.com/opencontainers/runc/libcontainer/configs" | ||
| "github.com/opencontainers/runc/libcontainer/system" | ||
| "github.com/sirupsen/logrus" | ||
| "github.com/vishvananda/netlink/nl" | ||
| "golang.org/x/sys/execabs" | ||
| "golang.org/x/sys/unix" | ||
| ) | ||
|
|
||
| // NsExecSyncMsg is used for communication between the parent and child during | ||
| // container setup. | ||
| type NsExecSyncMsg uint32 | ||
|
|
||
| const ( | ||
| syncUsermapPls NsExecSyncMsg = iota + 0x40 | ||
| syncUsermapAck | ||
| syncRecvPidPls | ||
| syncRecvPidAck | ||
| syncTimeOffsetsPls | ||
| syncTimeOffsetsAck | ||
| ) | ||
|
|
||
| type NsExecSetup struct { | ||
| process *containerProcess | ||
| } | ||
|
|
||
| const bufSize int = 4 | ||
|
|
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| // parseNsExecSync runs the given callback function on each message received | ||
| // from the child. It will return once the child sends SYNC_RECVPID_PLS. | ||
| func parseNsExecSync(r io.Reader, fn func(NsExecSyncMsg) error) error { | ||
| logrus.Debugf("start to communicate with the nsexec\n") | ||
| var msg NsExecSyncMsg | ||
| var buf [bufSize]byte | ||
| native := nl.NativeEndian() | ||
|
|
||
| for { | ||
| if _, err := io.ReadAtLeast(r, buf[:], bufSize); err != nil { | ||
| return err | ||
| } | ||
| msg = NsExecSyncMsg(native.Uint32(buf[:])) | ||
| if err := fn(msg); err != nil { | ||
| return err | ||
| } | ||
| if msg == syncRecvPidPls { | ||
| break | ||
| } | ||
| } | ||
| logrus.Debugf("finished communicating with the nsexec\n") | ||
| return nil | ||
| } | ||
|
|
||
| // ackSyncMsg is used to send a message to the child. | ||
| func ackSyncMsg(f *os.File, msg NsExecSyncMsg) error { | ||
| var buf [bufSize]byte | ||
| native := nl.NativeEndian() | ||
| native.PutUint32(buf[:], uint32(msg)) | ||
| if _, err := unix.Write(int(f.Fd()), buf[:]); err != nil { | ||
| logrus.Debugf("failed to write message to nsexec: %v", err) | ||
| return err | ||
| } | ||
| return nil | ||
| } | ||
|
|
||
| // helpDoingNsExec is used to help the process to communicate with the nsexec. | ||
| func (s *NsExecSetup) helpDoingNsExec() error { | ||
| return parseNsExecSync(s.process.comm.stage1SockParent, func(msg NsExecSyncMsg) error { | ||
| switch msg { | ||
| case syncUsermapPls: | ||
| logrus.Debugf("stage-1 requested userns mappings") | ||
| if err := s.setupUsermap(); err != nil { | ||
| return err | ||
| } | ||
| return ackSyncMsg(s.process.comm.stage1SockParent, syncUsermapAck) | ||
| case syncRecvPidPls: | ||
| logrus.Debugf("stage-1 reports pid") | ||
| if err := json.NewDecoder(s.process.comm.stage1SockParent).Decode(&s.process.childPid); err != nil { | ||
| return err | ||
| } | ||
| return ackSyncMsg(s.process.comm.stage1SockParent, syncRecvPidAck) | ||
| case syncTimeOffsetsPls: | ||
| logrus.Debugf("stage-1 requested timens offsets to be configured") | ||
| if err := system.UpdateTimeNsOffsets(s.process.cmd.Process.Pid, s.process.container.config.TimeOffsets); err != nil { | ||
| return err | ||
| } | ||
| return ackSyncMsg(s.process.comm.stage1SockParent, syncTimeOffsetsAck) | ||
| default: | ||
| } | ||
| return fmt.Errorf("unexpected message %d", msg) | ||
| }) | ||
| } | ||
|
|
||
| // setupUsermap is used to set up the user mappings. | ||
| func (s *NsExecSetup) setupUsermap() error { | ||
| var uidMapPath, gidMapPath string | ||
| /* | ||
| * Enable setgroups(2) if we've been asked to. But we also | ||
| * have to explicitly disable setgroups(2) if we're | ||
| * creating a rootless container for single-entry mapping. | ||
| * i.e. config.is_setgroup == false. | ||
| * (this is required since Linux 3.19). | ||
| * | ||
| * For rootless multi-entry mapping, config.is_setgroup shall be true and | ||
| * newuidmap/newgidmap shall be used. | ||
| */ | ||
| if s.process.config.RootlessEUID && !requiresRootOrMappingTool(s.process.config.Config.GIDMappings) { | ||
| _ = system.UpdateSetgroups(s.process.cmd.Process.Pid, system.SetgroupsDeny) | ||
| } | ||
|
|
||
| nsMaps := make(map[configs.NamespaceType]string) | ||
| for _, ns := range s.process.container.config.Namespaces { | ||
| if ns.Path != "" { | ||
| nsMaps[ns.Type] = ns.Path | ||
| } | ||
| } | ||
| _, joinExistingUser := nsMaps[configs.NEWUSER] | ||
| if !joinExistingUser { | ||
| // write uid mappings | ||
| if len(s.process.container.config.UIDMappings) > 0 { | ||
| if s.process.container.config.RootlessEUID { | ||
| if path, err := execabs.LookPath("newuidmap"); err == nil { | ||
| uidMapPath = path | ||
| } | ||
| } | ||
| } | ||
|
|
||
| // write gid mappings | ||
| if len(s.process.container.config.GIDMappings) > 0 { | ||
| if s.process.container.config.RootlessEUID { | ||
| if path, err := execabs.LookPath("newgidmap"); err == nil { | ||
| gidMapPath = path | ||
| } | ||
| } | ||
| } | ||
| } | ||
|
|
||
| /* Set up mappings. */ | ||
| if err := system.UpdateUidmap(uidMapPath, s.process.cmd.Process.Pid, s.process.container.config.UIDMappings); err != nil { | ||
| return err | ||
| } | ||
| return system.UpdateGidmap(gidMapPath, s.process.cmd.Process.Pid, s.process.container.config.GIDMappings) | ||
| } |
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