Merge pull request #48 from ahmetozer/feat/uid-gid

Feat/uid gid

Author: ahmetozer

pkg/cmd/exec.go

@@ -23,12 +23,15 @@ func ExecOnContainer(args []string) error {
 		EnvAll   bool
 		PassEnv  wrapper.StringFlags
 		Dir      string
+		User     string
 		contName string
 	)
 
 	f.BoolVar(&help, "help", false, "show this help message")
 	f.BoolVar(&EnvAll, "env-all", false, "send all enviroment variables to container")
 	f.StringVar(&Dir, "dir", "", "working directory")
+	f.StringVar(&User, "user", "", "work user")
+
 	f.Var(&PassEnv, "env-pass", "pass only requested enviroment variables to container")
 
 	// Allocate variable locations
@@ -90,7 +93,10 @@ func ExecOnContainer(args []string) error {
 		}
 	}
 
-	exitCode, err = cruntime.Exec(childArgs, "")
+	if User == "" {
+		User = c.User
+	}
+	exitCode, err = cruntime.Exec(childArgs, "", User)
 	if err != nil && strings.Contains(err.Error(), "exit status") {
 		err = nil
 	}

pkg/container/cruntime/exec.go

@@ -12,14 +12,14 @@ import (
 	"golang.org/x/sys/unix"
 )
 
-func runCommands(c []string, chroot string) {
+func runCommands(c []string, chroot string, user string) {
 	for _, command := range c {
-		Exec(cmdline.Parse(command), chroot)
+		Exec(cmdline.Parse(command), chroot, user)
 	}
 }
 
 // Execute under container chroot
-func Exec(c []string, chroot string) (exitCode int, err error) {
+func Exec(c []string, chroot string, user string) (exitCode int, err error) {
 	var (
 		cmd      *exec.Cmd
 		mainRoot *os.File
@@ -70,13 +70,24 @@ func Exec(c []string, chroot string) (exitCode int, err error) {
 		// Cloneflags: unix.CLONE_NEWUTS,
 	}
 
-	if chroot != "" {
-		cmd.SysProcAttr = &unix.SysProcAttr{
-			// Cloneflags: unix.CLONE_NEWUTS,
-			Chroot: chroot,
+	if user != "" {
+		u, err2 := getUser(user)
+		if err2 != nil {
+			err = err2
+			return
+		}
+
+		cmd.SysProcAttr.Credential = u.Credential
+		if u.User != nil && u.User.HomeDir != "" {
+			cmd.Dir = u.User.HomeDir
+			cmd.Env = append([]string{"HOME=" + u.User.HomeDir}, cmd.Env...)
 		}
 	}
 
+	if chroot != "" {
+		cmd.SysProcAttr.Chroot = chroot
+	}
+
 	err = cmd.Run()
 
 	if err != nil && err.Error() == "waitid: no child processes" {

pkg/container/cruntime/init.go

@@ -110,9 +110,10 @@ func ContainerInitProc() {
 		if err != nil {
 			return err
 		}
-		runCommands(c.RunPrePivot, "/.old_root/")
+		// do not execute pre commands as defined user
+		runCommands(c.RunPrePivot, "/.old_root/", "")
 		purgeOldRoot(c)
-		runCommands(c.RunPreExec, "")
+		runCommands(c.RunPreExec, "", "")
 
 		if len(c.ContArgs) == 0 {
 			return fmt.Errorf("no container arg providen, malformed container file")
@@ -127,7 +128,11 @@ func ContainerInitProc() {
 			os.Chdir(c.Dir)
 		}
 
-		err = switchUser(c.User)
+		user, err := getUser(c.User)
+		if err != nil {
+			return err
+		}
+		err = switchUser(user)
 		if err != nil {
 			return err
 		}

pkg/container/cruntime/namespace/allocate.go

@@ -1,6 +1,12 @@
 package namespace
 
 func (ns *NamespaceConf) defaults() {
+
+	if ns.UserValue == nil {
+		temp := ""
+		ns.UserValue = &temp
+	}
+
 	switch *ns.UserValue {
 	case "host":
 		ns.IsHost = true

pkg/container/cruntime/user.go

@@ -1,54 +1,90 @@
 package cruntime
 
 import (
+	"os"
 	os_user "os/user"
 	"strconv"
 	"strings"
 	"syscall"
 )
 
-func switchUser(user string) (err error) {
+type User struct {
+	Credential *syscall.Credential
+	User       *os_user.User
+}
 
-	if user == "" {
-		return nil
+func getUser(ug string) (User User, err error) {
+	if ug == "" {
+		return
 	}
 
 	var (
-		uid int
-		gid int
+		uid uint64
+		gid uint64
 	)
-	credential := strings.Split(user, ":")
+	user_group := strings.Split(ug, ":")
 
-	if uid, err = strconv.Atoi(credential[0]); err != nil {
-		user, err := os_user.Lookup(credential[0])
+	if uid, err = strconv.ParseUint(user_group[0], 10, 32); err != nil {
+		User.User, err = os_user.Lookup(user_group[0])
 		if err == nil {
-			uid, _ = strconv.Atoi(user.Uid)
+			uid, _ = strconv.ParseUint(User.User.Uid, 10, 32)
 			// if usergroup is not presented, try gid info from user information
 
-			if len(credential) == 1 && user.Gid != "" {
-				credential = append(credential, user.Gid)
+			if len(user_group) == 1 && User.User.Gid != "" {
+				user_group = append(user_group, User.User.Gid)
 			}
 		} else {
-			return err
+			return
 		}
+
 	}
 
 	// if usergroup is not presented, set group name identical to username
-	if len(credential) == 1 {
-		credential = append(credential, credential[0])
+	if len(user_group) == 1 {
+		user_group = append(user_group, user_group[0])
 	}
 
-	if gid, err = strconv.Atoi(credential[1]); err != nil {
-		group, err := os_user.LookupGroup(credential[1])
+	if gid, err = strconv.ParseUint(user_group[1], 10, 32); err != nil {
+		group, err := os_user.LookupGroup(user_group[1])
 		if err == nil {
-			gid, _ = strconv.Atoi(group.Gid)
+			gid, _ = strconv.ParseUint(group.Gid, 10, 32)
 		}
 	}
 
-	err = syscall.Setgid(gid)
+	User.Credential = &syscall.Credential{}
+	User.Credential.Uid = uint32(uid)
+	User.Credential.Gid = uint32(gid)
+
+	return
+}
+
+func switchUser(user User) error {
+	err := switchCredential(user.Credential)
 	if err != nil {
 		return err
 	}
-	err = syscall.Setuid(uid)
+
+	if user.User == nil {
+		return nil
+	}
+
+	if user.User.HomeDir != "" {
+		os.Chdir(user.User.HomeDir)
+	}
+
+	return nil
+}
+
+func switchCredential(Credential *syscall.Credential) (err error) {
+	if Credential == nil {
+		return
+	}
+	err = syscall.Setgid(int(Credential.Gid))
+	if err != nil {
+		return
+	}
+
+	err = syscall.Setuid(int(Credential.Uid))
+
 	return
 }