mirror of
https://github.com/criyle/go-sandbox.git
synced 2025-11-04 14:49:53 +08:00
286 lines
6.9 KiB
Go
286 lines
6.9 KiB
Go
package daemon
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import (
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"bytes"
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"encoding/gob"
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"fmt"
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"io"
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"os"
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"syscall"
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"github.com/criyle/go-sandbox/pkg/forkexec"
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"github.com/criyle/go-sandbox/pkg/unixsocket"
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"github.com/criyle/go-sandbox/types"
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)
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// Init is called for container init process
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// it will check if pid == 1, otherwise it is noop
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// Init will do infinite loop on socket commands,
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// and exits when at socket close, use it in init function
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func Init() (err error) {
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// noop if self is not container init process
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// Notice: docker init is also 1, additional check for args[1] == init
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if os.Getpid() != 1 || len(os.Args) != 2 || os.Args[1] != initArg {
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return nil
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}
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// exit process (with whole container) upon exit this function
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defer func() {
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if err2 := recover(); err2 != nil {
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fmt.Fprintf(os.Stderr, "container_panic: %v", err)
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os.Exit(1)
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}
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if err != nil {
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fmt.Fprintf(os.Stderr, "container_exit: %v", err)
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os.Exit(1)
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} else {
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fmt.Fprintf(os.Stderr, "container_exit")
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os.Exit(0)
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}
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}()
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// new_master shared the socket at fd 3 (marked close_exec)
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soc, err := unixsocket.NewSocket(3)
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if err != nil {
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return fmt.Errorf("container_init: faile to new socket(%v)", err)
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}
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for {
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cmd, msg, err := recvCmd(soc)
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if err != nil {
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return fmt.Errorf("loop: %v", err)
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}
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if err := handleCmd(soc, cmd, msg); err != nil {
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return fmt.Errorf("loop: failed to execute cmd(%v)", err)
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}
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}
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}
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func handleCmd(s *unixsocket.Socket, cmd *Cmd, msg *unixsocket.Msg) error {
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switch cmd.Cmd {
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case cmdPing:
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return handlePing(s)
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case cmdCopyIn:
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return handleCopyIn(s, cmd, msg)
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case cmdOpen:
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return handleOpen(s, cmd)
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case cmdDelete:
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return handleDelete(s, cmd)
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case cmdReset:
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return handleReset(s)
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case cmdExecve:
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return handleExecve(s, cmd, msg)
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}
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return fmt.Errorf("Unknown command: %v", cmd.Cmd)
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}
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func handlePing(s *unixsocket.Socket) error {
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return sendReply(s, &Reply{}, nil)
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}
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func handleCopyIn(s *unixsocket.Socket, cmd *Cmd, msg *unixsocket.Msg) error {
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if len(msg.Fds) != 1 {
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closeFds(msg.Fds)
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return sendErrorReply(s, "copyin: unexpected number of fds(%d)", len(msg.Fds))
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}
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inf := os.NewFile(uintptr(msg.Fds[0]), cmd.Path)
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if inf == nil {
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return sendErrorReply(s, "copyin: newfile failed %v", msg.Fds[0])
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}
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defer inf.Close()
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// have 0777 permission to be able copy in executables
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outf, err := os.OpenFile(cmd.Path, os.O_CREATE|os.O_RDWR|os.O_TRUNC, 0777)
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if err != nil {
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return sendErrorReply(s, "copyin: open write file %v", err)
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}
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defer outf.Close()
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_, err = io.Copy(outf, inf)
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if err != nil {
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return sendErrorReply(s, "copyin: io.copy %v", err)
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}
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return sendReply(s, &Reply{}, nil)
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}
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func handleOpen(s *unixsocket.Socket, cmd *Cmd) error {
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outf, err := os.Open(cmd.Path)
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if err != nil {
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return sendErrorReply(s, "open: %v", err)
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}
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defer outf.Close()
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return sendReply(s, &Reply{}, &unixsocket.Msg{
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Fds: []int{int(outf.Fd())},
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})
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}
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func handleDelete(s *unixsocket.Socket, cmd *Cmd) error {
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if err := os.Remove(cmd.Path); err != nil {
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return sendErrorReply(s, "delete: %v", err)
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}
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return sendReply(s, &Reply{}, nil)
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}
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func handleReset(s *unixsocket.Socket) error {
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if err := removeContents("/tmp"); err != nil {
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return sendErrorReply(s, "reset: /tmp %v", err)
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}
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if err := removeContents("/w"); err != nil {
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return sendErrorReply(s, "reset: /w %v", err)
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}
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return sendReply(s, &Reply{}, nil)
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}
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func handleExecve(s *unixsocket.Socket, cmd *Cmd, msg *unixsocket.Msg) error {
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var (
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files []uintptr
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execFile uintptr
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)
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if msg != nil {
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files = intSliceToUintptr(msg.Fds)
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// don't leak fds to child
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closeOnExecFds(msg.Fds)
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// release files after execve
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defer closeFds(msg.Fds)
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}
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// if fexecve, then the first fd must be executable
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if cmd.FdExec {
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if len(files) == 0 {
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return fmt.Errorf("execve: expected fexecve fd")
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}
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execFile = files[0]
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files = files[1:]
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}
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syncFunc := func(pid int) error {
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msg2 := unixsocket.Msg{
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Cred: &syscall.Ucred{
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Pid: int32(pid),
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Uid: uint32(syscall.Getuid()),
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Gid: uint32(syscall.Getgid()),
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},
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}
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if err2 := sendReply(s, &Reply{}, &msg2); err2 != nil {
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return fmt.Errorf("syncFunc: sendReply(%v)", err2)
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}
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cmd2, _, err2 := recvCmd(s)
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if err2 != nil {
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return fmt.Errorf("syncFunc: recvCmd(%v)", err2)
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}
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if cmd2.Cmd == cmdKill {
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return fmt.Errorf("syncFunc: recved kill")
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}
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return nil
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}
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r := forkexec.Runner{
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Args: cmd.Argv,
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Env: cmd.Envv,
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ExecFile: execFile,
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RLimits: cmd.RLmits,
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Files: files,
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WorkDir: "/w",
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NoNewPrivs: true,
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DropCaps: true,
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SyncFunc: syncFunc,
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}
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// starts the runner, error is handled same as wait4 to make communication equal
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pid, err := r.Start()
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// done is to signal kill goroutine exits
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killDone := make(chan struct{})
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// waitDone is to signal kill goroutine to collect zombies
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waitDone := make(chan struct{})
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// recv kill
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go func() {
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// signal done
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defer close(killDone)
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// msg must be kill
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recvCmd(s)
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// kill all
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syscall.Kill(-1, syscall.SIGKILL)
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// make sure collect zombie does not consume the exit status
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<-waitDone
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// collect zombies
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for {
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if pid, err := syscall.Wait4(-1, nil, syscall.WNOHANG, nil); err != nil || pid <= 0 {
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break
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}
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}
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}()
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// wait pid if no error encoutered for execve
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var wstatus syscall.WaitStatus
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if err == nil {
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_, err = syscall.Wait4(pid, &wstatus, 0, nil)
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}
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// sync with kill goroutine
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close(waitDone)
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if err != nil {
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sendErrorReply(s, "execve: wait4 %v", err)
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} else {
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switch {
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case wstatus.Exited():
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sendReply(s, &Reply{ExitStatus: wstatus.ExitStatus()}, nil)
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case wstatus.Signaled():
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var status types.Status
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switch wstatus.Signal() {
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// kill signal treats as TLE
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case syscall.SIGXCPU, syscall.SIGKILL:
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status = types.StatusTLE
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case syscall.SIGXFSZ:
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status = types.StatusOLE
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case syscall.SIGSYS:
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status = types.StatusBan
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default:
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status = types.StatusRE
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}
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sendReply(s, &Reply{Status: status}, nil)
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default:
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sendErrorReply(s, "execve: unknown status %v", wstatus)
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}
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}
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// wait for kill msg and reply done for finish
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<-killDone
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return sendReply(s, &Reply{}, nil)
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}
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func recvCmd(s *unixsocket.Socket) (*Cmd, *unixsocket.Msg, error) {
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var cmd Cmd
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buffer := GetBuffer()
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defer PutBuffer(buffer)
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n, msg, err := s.RecvMsg(buffer)
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if err != nil {
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return nil, nil, fmt.Errorf("failed RecvMsg(%v)", err)
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}
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if err := gob.NewDecoder(bytes.NewReader(buffer[:n])).Decode(&cmd); err != nil {
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return nil, nil, fmt.Errorf("failed to decode(%v)", err)
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}
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return &cmd, msg, nil
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}
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func sendReply(s *unixsocket.Socket, reply *Reply, msg *unixsocket.Msg) error {
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var buffer bytes.Buffer
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if err := gob.NewEncoder(&buffer).Encode(reply); err != nil {
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return err
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}
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if err := s.SendMsg(buffer.Bytes(), msg); 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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// sendErrorReply sends error reply
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func sendErrorReply(s *unixsocket.Socket, ft string, v ...interface{}) error {
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reply := Reply{Error: fmt.Sprintf(ft, v...)}
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return sendReply(s, &reply, nil)
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}
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