mirror of
https://github.com/criyle/go-sandbox.git
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165 lines
4.0 KiB
Go
165 lines
4.0 KiB
Go
package daemon
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import (
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"fmt"
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"io"
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"os"
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"github.com/criyle/go-sandbox/pkg/unixsocket"
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)
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type containerServer struct {
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socket *unixsocket.Socket
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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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// possible reason:
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// 1. socket broken (parent exit)
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// 2. panic
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// 3. undefined cmd (possible race condition)
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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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}
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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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// new_master shared the socket at fd 3 (marked close_exec)
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const defaultFd = 3
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soc, err := unixsocket.NewSocket(defaultFd)
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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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// serve forever
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cs := &containerServer{soc}
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return cs.serve()
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}
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func (c *containerServer) serve() error {
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for {
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cmd, msg, err := c.recvCmd()
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if err != nil {
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return fmt.Errorf("serve: %v", err)
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}
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if err := c.handleCmd(cmd, msg); err != nil {
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return fmt.Errorf("serve: failed to execute cmd %v", err)
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}
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}
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}
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func (c *containerServer) handleCmd(cmd *Cmd, msg *unixsocket.Msg) error {
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switch cmd.Cmd {
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case cmdPing:
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return c.handlePing()
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case cmdCopyIn:
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return c.handleCopyIn(cmd, msg)
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case cmdOpen:
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return c.handleOpen(cmd)
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case cmdDelete:
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return c.handleDelete(cmd)
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case cmdReset:
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return c.handleReset()
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case cmdExecve:
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return c.handleExecve(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 (c *containerServer) handlePing() error {
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return c.sendReply(&Reply{}, nil)
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}
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func (c *containerServer) handleCopyIn(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 c.sendErrorReply("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 c.sendErrorReply("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 c.sendErrorReply("copyin: open write file %v", err)
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}
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defer outf.Close()
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if _, err = io.Copy(outf, inf); err != nil {
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return c.sendErrorReply("copyin: io.copy %v", err)
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}
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return c.sendReply(&Reply{}, nil)
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}
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func (c *containerServer) handleOpen(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 c.sendErrorReply("open: %v", err)
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}
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defer outf.Close()
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return c.sendReply(&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 (c *containerServer) handleDelete(cmd *Cmd) error {
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if err := os.Remove(cmd.Path); err != nil {
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return c.sendErrorReply("delete: %v", err)
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}
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return c.sendReply(&Reply{}, nil)
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}
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func (c *containerServer) handleReset() error {
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if err := removeContents("/tmp"); err != nil {
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return c.sendErrorReply("reset: /tmp %v", err)
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}
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if err := removeContents("/w"); err != nil {
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return c.sendErrorReply("reset: /w %v", err)
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}
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return c.sendReply(&Reply{}, nil)
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}
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func (c *containerServer) recvCmd() (*Cmd, *unixsocket.Msg, error) {
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cmd := new(Cmd)
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msg, err := (*socket)(c.socket).RecvMsg(cmd)
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if err != nil {
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return nil, nil, err
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}
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return cmd, msg, nil
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}
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func (c *containerServer) sendReply(reply *Reply, msg *unixsocket.Msg) error {
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return (*socket)(c.socket).SendMsg(reply, msg)
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}
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// sendErrorReply sends error reply
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func (c *containerServer) sendErrorReply(ft string, v ...interface{}) error {
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return c.sendReply(&Reply{Error: fmt.Sprintf(ft, v...)}, nil)
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}
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