2013-10-10 08:53:38 +00:00
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package sysinit
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2013-02-13 22:01:44 +00:00
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import (
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2013-08-15 00:14:30 +00:00
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"encoding/json"
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2013-02-14 01:24:35 +00:00
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"flag"
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2013-02-13 22:01:44 +00:00
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"fmt"
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2013-09-17 13:02:12 +00:00
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"github.com/dotcloud/docker/netlink"
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2013-07-01 23:48:59 +00:00
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"github.com/dotcloud/docker/utils"
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2013-08-13 22:40:23 +00:00
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"io/ioutil"
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2013-02-13 22:01:44 +00:00
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"log"
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2013-09-17 13:02:12 +00:00
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"net"
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2013-02-13 22:01:44 +00:00
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"os"
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"os/exec"
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2013-02-14 01:24:35 +00:00
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"strconv"
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2013-03-24 02:11:00 +00:00
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"strings"
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2013-02-13 22:01:44 +00:00
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"syscall"
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)
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2013-12-02 18:58:45 +00:00
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type DockerInitArgs struct {
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user string
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gateway string
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workDir string
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env []string
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args []string
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}
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2013-02-21 01:45:46 +00:00
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// Setup networking
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2013-12-02 18:58:45 +00:00
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func setupNetworking(args *DockerInitArgs) {
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if args.gateway == "" {
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2013-02-21 01:45:46 +00:00
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return
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}
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2013-09-17 13:02:12 +00:00
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2013-12-02 18:58:45 +00:00
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ip := net.ParseIP(args.gateway)
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2013-09-17 13:02:12 +00:00
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if ip == nil {
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2013-12-02 18:58:45 +00:00
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log.Fatalf("Unable to set up networking, %s is not a valid IP", args.gateway)
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2013-09-17 13:02:12 +00:00
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return
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}
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if err := netlink.AddDefaultGw(ip); err != nil {
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2013-02-21 01:45:46 +00:00
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log.Fatalf("Unable to set up networking: %v", err)
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}
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}
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2013-08-15 18:38:17 +00:00
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// Setup working directory
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2013-12-02 18:58:45 +00:00
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func setupWorkingDirectory(args *DockerInitArgs) {
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if args.workDir == "" {
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2013-08-15 18:38:17 +00:00
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return
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}
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2013-12-02 18:58:45 +00:00
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if err := syscall.Chdir(args.workDir); err != nil {
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log.Fatalf("Unable to change dir to %v: %v", args.workDir, err)
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2013-10-14 07:27:38 +00:00
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}
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2013-08-15 18:38:17 +00:00
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}
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2013-02-14 01:24:35 +00:00
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// Takes care of dropping privileges to the desired user
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2013-12-02 18:58:45 +00:00
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func changeUser(args *DockerInitArgs) {
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if args.user == "" {
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2013-02-14 01:24:35 +00:00
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return
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}
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2013-12-02 18:58:45 +00:00
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userent, err := utils.UserLookup(args.user)
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2013-02-14 01:24:35 +00:00
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if err != nil {
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2013-12-02 18:58:45 +00:00
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log.Fatalf("Unable to find user %v: %v", args.user, err)
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2013-02-14 01:24:35 +00:00
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}
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uid, err := strconv.Atoi(userent.Uid)
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if err != nil {
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log.Fatalf("Invalid uid: %v", userent.Uid)
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}
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gid, err := strconv.Atoi(userent.Gid)
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if err != nil {
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log.Fatalf("Invalid gid: %v", userent.Gid)
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}
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if err := syscall.Setgid(gid); err != nil {
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log.Fatalf("setgid failed: %v", err)
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}
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if err := syscall.Setuid(uid); err != nil {
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log.Fatalf("setuid failed: %v", err)
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}
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}
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2013-03-24 02:11:00 +00:00
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// Clear environment pollution introduced by lxc-start
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2013-12-02 18:58:45 +00:00
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func setupEnv(args *DockerInitArgs) {
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2013-03-24 02:11:00 +00:00
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os.Clearenv()
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2013-12-02 18:58:45 +00:00
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for _, kv := range args.env {
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2013-03-24 02:11:00 +00:00
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parts := strings.SplitN(kv, "=", 2)
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if len(parts) == 1 {
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parts = append(parts, "")
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}
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os.Setenv(parts[0], parts[1])
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}
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}
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2013-12-02 18:58:45 +00:00
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func executeProgram(args *DockerInitArgs) {
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path, err := exec.LookPath(args.args[0])
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2013-02-14 01:24:35 +00:00
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if err != nil {
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2013-12-02 18:58:45 +00:00
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log.Printf("Unable to locate %v", args.args[0])
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2013-02-14 01:24:35 +00:00
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os.Exit(127)
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}
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2013-12-02 18:58:45 +00:00
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if err := syscall.Exec(path, args.args, os.Environ()); err != nil {
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2013-02-14 01:24:35 +00:00
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panic(err)
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}
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}
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2013-02-13 22:01:44 +00:00
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// Sys Init code
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// This code is run INSIDE the container and is responsible for setting
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// up the environment before running the actual process
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func SysInit() {
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if len(os.Args) <= 1 {
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2013-10-18 05:39:57 +00:00
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fmt.Println("You should not invoke dockerinit manually")
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2013-02-13 22:01:44 +00:00
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os.Exit(1)
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}
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2013-12-02 18:58:45 +00:00
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// Get cmdline arguments
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user := flag.String("u", "", "username or uid")
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gateway := flag.String("g", "", "gateway address")
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workDir := flag.String("w", "", "workdir")
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2013-02-14 01:24:35 +00:00
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flag.Parse()
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2013-02-21 01:45:46 +00:00
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2013-12-02 18:58:45 +00:00
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// Get env
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var env []string
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content, err := ioutil.ReadFile("/.dockerenv")
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if err != nil {
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log.Fatalf("Unable to load environment variables: %v", err)
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}
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if err := json.Unmarshal(content, &env); err != nil {
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log.Fatalf("Unable to unmarshal environment variables: %v", err)
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}
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args := &DockerInitArgs{
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user: *user,
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gateway: *gateway,
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workDir: *workDir,
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env: env,
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args: flag.Args(),
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}
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setupEnv(args)
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setupNetworking(args)
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setupWorkingDirectory(args)
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changeUser(args)
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executeProgram(args)
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2013-02-13 22:01:44 +00:00
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}
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