refactor: move some c code to go #4309
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,147 @@ | ||
| package libcontainer | ||
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||
| import ( | ||
| "encoding/binary" | ||
| "fmt" | ||
| "io" | ||
| "os" | ||
| "os/exec" | ||
|
|
||
| "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/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 | ||
| ) | ||
|
|
||
| const bufSize = 4 | ||
|
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| // setupNsExec is used to help nsexec to setup the container and wait the container's pid. | ||
| func (s *containerProcess) setupNsExec(syncSock *os.File) error { | ||
| logrus.Debugf("waiting nsexec to report the container's pid") | ||
| err := ParseNsExecSync(syncSock, func(msg NsExecSyncMsg) error { | ||
| switch msg { | ||
| case SyncUsermapPls: | ||
| logrus.Debugf("nsexec has requested userns mappings") | ||
| if err := s.setupUsermap(); err != nil { | ||
| return err | ||
| } | ||
| return AckNsExecSync(syncSock, SyncUsermapAck) | ||
| case SyncTimeOffsetsPls: | ||
| logrus.Debugf("nsexec has requested to configure timens offsets") | ||
| if err := system.UpdateTimeNsOffsets(s.cmd.Process.Pid, s.container.config.TimeOffsets); err != nil { | ||
| return err | ||
| } | ||
| return AckNsExecSync(syncSock, SyncTimeOffsetsAck) | ||
| case SyncRecvPidPls: | ||
| logrus.Debugf("nsexec has reported pid") | ||
| var pid uint32 | ||
| if err := binary.Read(syncSock, nl.NativeEndian(), &pid); err != nil { | ||
| return err | ||
| } | ||
| s.childPid = int(pid) | ||
| return AckNsExecSync(syncSock, SyncRecvPidAck) | ||
| default: | ||
| return fmt.Errorf("unexpected message %d", msg) | ||
| } | ||
| }) | ||
|
|
||
| return err | ||
| } | ||
|
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| // setupUsermap is used to set up the user mappings. | ||
| func (s *containerProcess) setupUsermap() error { | ||
| var uidMapPath, gidMapPath string | ||
|
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| // 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. (this is required since Linux 3.19). | ||
| // For rootless multi-entry mapping, we should use newuidmap/newgidmap | ||
| // to do mapping user namespace. | ||
| if s.config.Config.RootlessEUID && !requiresRootOrMappingTool(s.config.Config.GIDMappings) { | ||
| _ = system.UpdateSetgroups(s.cmd.Process.Pid, system.SetgroupsDeny) | ||
| } | ||
|
|
||
| nsMaps := make(map[configs.NamespaceType]string) | ||
| for _, ns := range s.container.config.Namespaces { | ||
| if ns.Path != "" { | ||
| nsMaps[ns.Type] = ns.Path | ||
| } | ||
| } | ||
| _, joinExistingUser := nsMaps[configs.NEWUSER] | ||
| if !joinExistingUser { | ||
| // write uid mappings | ||
| if len(s.container.config.UIDMappings) > 0 { | ||
| if s.container.config.RootlessEUID { | ||
| if path, err := exec.LookPath("newuidmap"); err == nil { | ||
| uidMapPath = path | ||
| } | ||
| } | ||
| } | ||
|
|
||
| // write gid mappings | ||
| if len(s.container.config.GIDMappings) > 0 { | ||
| if s.container.config.RootlessEUID { | ||
| if path, err := exec.LookPath("newgidmap"); err == nil { | ||
| gidMapPath = path | ||
| } | ||
| } | ||
| } | ||
| } | ||
|
|
||
| /* Set up mappings. */ | ||
| if err := system.UpdateUidmap(uidMapPath, s.cmd.Process.Pid, s.container.config.UIDMappings); err != nil { | ||
| return err | ||
| } | ||
| return system.UpdateGidmap(gidMapPath, s.cmd.Process.Pid, s.container.config.GIDMappings) | ||
| } | ||
|
|
||
| // 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 { | ||
| var ( | ||
| msg NsExecSyncMsg | ||
| 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 | ||
| } | ||
| } | ||
| return nil | ||
| } | ||
|
|
||
| // AckNsExecSync is used to send a message to the child. | ||
| func AckNsExecSync(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 | ||
| } | ||
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I guess we need to handle when it returns EINTR now that this is go. This applies to all functions that can return EINTR and are using the unix or syscall package.