370 lines
9.7 KiB
Go
370 lines
9.7 KiB
Go
// +build linux
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package libcontainer
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import (
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"encoding/json"
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"fmt"
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"io"
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"io/ioutil"
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"net"
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"os"
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"strconv"
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"strings"
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"syscall"
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"github.com/Sirupsen/logrus"
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"github.com/opencontainers/runc/libcontainer/cgroups"
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"github.com/opencontainers/runc/libcontainer/configs"
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"github.com/opencontainers/runc/libcontainer/system"
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"github.com/opencontainers/runc/libcontainer/user"
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"github.com/opencontainers/runc/libcontainer/utils"
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"github.com/vishvananda/netlink"
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)
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type initType string
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const (
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initSetns initType = "setns"
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initStandard initType = "standard"
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)
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type pid struct {
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Pid int `json:"pid"`
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}
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// network is an internal struct used to setup container networks.
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type network struct {
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configs.Network
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// TempVethPeerName is a unique temporary veth peer name that was placed into
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// the container's namespace.
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TempVethPeerName string `json:"temp_veth_peer_name"`
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}
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// initConfig is used for transferring parameters from Exec() to Init()
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type initConfig struct {
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Args []string `json:"args"`
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Env []string `json:"env"`
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Cwd string `json:"cwd"`
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Capabilities []string `json:"capabilities"`
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ProcessLabel string `json:"process_label"`
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AppArmorProfile string `json:"apparmor_profile"`
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NoNewPrivileges bool `json:"no_new_privileges"`
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User string `json:"user"`
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AdditionalGroups []string `json:"additional_groups"`
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Config *configs.Config `json:"config"`
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Console string `json:"console"`
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Networks []*network `json:"network"`
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PassedFilesCount int `json:"passed_files_count"`
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ContainerId string `json:"containerid"`
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Rlimits []configs.Rlimit `json:"rlimits"`
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ExecFifoPath string `json:"start_pipe_path"`
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}
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type initer interface {
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Init() error
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}
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func newContainerInit(t initType, pipe *os.File, stateDirFD int) (initer, error) {
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var config *initConfig
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if err := json.NewDecoder(pipe).Decode(&config); err != nil {
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return nil, err
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}
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if err := populateProcessEnvironment(config.Env); err != nil {
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return nil, err
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}
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switch t {
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case initSetns:
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return &linuxSetnsInit{
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config: config,
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}, nil
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case initStandard:
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return &linuxStandardInit{
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pipe: pipe,
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parentPid: syscall.Getppid(),
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config: config,
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stateDirFD: stateDirFD,
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}, nil
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}
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return nil, fmt.Errorf("unknown init type %q", t)
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}
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// populateProcessEnvironment loads the provided environment variables into the
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// current processes's environment.
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func populateProcessEnvironment(env []string) error {
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for _, pair := range env {
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p := strings.SplitN(pair, "=", 2)
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if len(p) < 2 {
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return fmt.Errorf("invalid environment '%v'", pair)
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}
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if err := os.Setenv(p[0], p[1]); err != nil {
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return err
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}
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}
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return nil
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}
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// finalizeNamespace drops the caps, sets the correct user
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// and working dir, and closes any leaked file descriptors
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// before executing the command inside the namespace
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func finalizeNamespace(config *initConfig) error {
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// Ensure that all unwanted fds we may have accidentally
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// inherited are marked close-on-exec so they stay out of the
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// container
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if err := utils.CloseExecFrom(config.PassedFilesCount + 3); err != nil {
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return err
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}
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capabilities := config.Config.Capabilities
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if config.Capabilities != nil {
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capabilities = config.Capabilities
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}
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w, err := newCapWhitelist(capabilities)
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if err != nil {
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return err
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}
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// drop capabilities in bounding set before changing user
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if err := w.dropBoundingSet(); err != nil {
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return err
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}
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// preserve existing capabilities while we change users
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if err := system.SetKeepCaps(); err != nil {
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return err
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}
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if err := setupUser(config); err != nil {
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return err
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}
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if err := system.ClearKeepCaps(); err != nil {
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return err
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}
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// drop all other capabilities
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if err := w.drop(); err != nil {
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return err
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}
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if config.Cwd != "" {
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if err := syscall.Chdir(config.Cwd); err != nil {
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return err
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}
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}
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return nil
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}
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// syncParentReady sends to the given pipe a JSON payload which indicates that
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// the init is ready to Exec the child process. It then waits for the parent to
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// indicate that it is cleared to Exec.
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func syncParentReady(pipe io.ReadWriter) error {
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// Tell parent.
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if err := utils.WriteJSON(pipe, syncT{procReady}); err != nil {
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return err
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}
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// Wait for parent to give the all-clear.
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var procSync syncT
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if err := json.NewDecoder(pipe).Decode(&procSync); err != nil {
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if err == io.EOF {
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return fmt.Errorf("parent closed synchronisation channel")
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}
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if procSync.Type != procRun {
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return fmt.Errorf("invalid synchronisation flag from parent")
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}
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}
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return nil
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}
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// syncParentHooks sends to the given pipe a JSON payload which indicates that
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// the parent should execute pre-start hooks. It then waits for the parent to
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// indicate that it is cleared to resume.
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func syncParentHooks(pipe io.ReadWriter) error {
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// Tell parent.
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if err := utils.WriteJSON(pipe, syncT{procHooks}); err != nil {
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return err
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}
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// Wait for parent to give the all-clear.
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var procSync syncT
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if err := json.NewDecoder(pipe).Decode(&procSync); err != nil {
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if err == io.EOF {
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return fmt.Errorf("parent closed synchronisation channel")
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}
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if procSync.Type != procResume {
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return fmt.Errorf("invalid synchronisation flag from parent")
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}
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}
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return nil
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}
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// setupUser changes the groups, gid, and uid for the user inside the container
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func setupUser(config *initConfig) error {
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// Set up defaults.
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defaultExecUser := user.ExecUser{
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Uid: syscall.Getuid(),
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Gid: syscall.Getgid(),
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Home: "/",
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}
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passwdPath, err := user.GetPasswdPath()
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if err != nil {
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return err
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}
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groupPath, err := user.GetGroupPath()
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if err != nil {
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return err
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}
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execUser, err := user.GetExecUserPath(config.User, &defaultExecUser, passwdPath, groupPath)
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if err != nil {
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return err
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}
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var addGroups []int
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if len(config.AdditionalGroups) > 0 {
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addGroups, err = user.GetAdditionalGroupsPath(config.AdditionalGroups, groupPath)
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if err != nil {
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return err
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}
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}
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// before we change to the container's user make sure that the processes STDIO
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// is correctly owned by the user that we are switching to.
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if err := fixStdioPermissions(execUser); err != nil {
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return err
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}
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suppGroups := append(execUser.Sgids, addGroups...)
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if err := syscall.Setgroups(suppGroups); err != nil {
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return err
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}
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if err := system.Setgid(execUser.Gid); err != nil {
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return err
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}
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if err := system.Setuid(execUser.Uid); err != nil {
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return err
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}
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// if we didn't get HOME already, set it based on the user's HOME
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if envHome := os.Getenv("HOME"); envHome == "" {
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if err := os.Setenv("HOME", execUser.Home); err != nil {
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return err
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}
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}
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return nil
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}
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// fixStdioPermissions fixes the permissions of PID 1's STDIO within the container to the specified user.
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// The ownership needs to match because it is created outside of the container and needs to be
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// localized.
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func fixStdioPermissions(u *user.ExecUser) error {
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var null syscall.Stat_t
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if err := syscall.Stat("/dev/null", &null); err != nil {
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return err
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}
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for _, fd := range []uintptr{
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os.Stdin.Fd(),
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os.Stderr.Fd(),
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os.Stdout.Fd(),
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} {
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var s syscall.Stat_t
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if err := syscall.Fstat(int(fd), &s); err != nil {
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return err
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}
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// skip chown of /dev/null if it was used as one of the STDIO fds.
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if s.Rdev == null.Rdev {
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continue
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}
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if err := syscall.Fchown(int(fd), u.Uid, u.Gid); err != nil {
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return err
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}
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}
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return nil
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}
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// setupNetwork sets up and initializes any network interface inside the container.
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func setupNetwork(config *initConfig) error {
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for _, config := range config.Networks {
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strategy, err := getStrategy(config.Type)
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if err != nil {
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return err
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}
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if err := strategy.initialize(config); err != nil {
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return err
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}
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}
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return nil
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}
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func setupRoute(config *configs.Config) error {
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for _, config := range config.Routes {
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_, dst, err := net.ParseCIDR(config.Destination)
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if err != nil {
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return err
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}
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src := net.ParseIP(config.Source)
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if src == nil {
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return fmt.Errorf("Invalid source for route: %s", config.Source)
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}
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gw := net.ParseIP(config.Gateway)
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if gw == nil {
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return fmt.Errorf("Invalid gateway for route: %s", config.Gateway)
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}
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l, err := netlink.LinkByName(config.InterfaceName)
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if err != nil {
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return err
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}
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route := &netlink.Route{
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Scope: netlink.SCOPE_UNIVERSE,
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Dst: dst,
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Src: src,
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Gw: gw,
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LinkIndex: l.Attrs().Index,
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}
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if err := netlink.RouteAdd(route); err != nil {
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return err
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}
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}
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return nil
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}
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func setupRlimits(limits []configs.Rlimit, pid int) error {
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for _, rlimit := range limits {
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if err := system.Prlimit(pid, rlimit.Type, syscall.Rlimit{Max: rlimit.Hard, Cur: rlimit.Soft}); err != nil {
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return fmt.Errorf("error setting rlimit type %v: %v", rlimit.Type, err)
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}
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}
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return nil
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}
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func setOomScoreAdj(oomScoreAdj int, pid int) error {
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path := fmt.Sprintf("/proc/%d/oom_score_adj", pid)
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return ioutil.WriteFile(path, []byte(strconv.Itoa(oomScoreAdj)), 0600)
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}
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// killCgroupProcesses freezes then iterates over all the processes inside the
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// manager's cgroups sending a SIGKILL to each process then waiting for them to
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// exit.
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func killCgroupProcesses(m cgroups.Manager) error {
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var procs []*os.Process
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if err := m.Freeze(configs.Frozen); err != nil {
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logrus.Warn(err)
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}
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pids, err := m.GetAllPids()
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if err != nil {
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m.Freeze(configs.Thawed)
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return err
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}
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for _, pid := range pids {
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p, err := os.FindProcess(pid)
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if err != nil {
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logrus.Warn(err)
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continue
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}
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procs = append(procs, p)
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if err := p.Kill(); err != nil {
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logrus.Warn(err)
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}
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}
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if err := m.Freeze(configs.Thawed); err != nil {
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logrus.Warn(err)
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}
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for _, p := range procs {
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if _, err := p.Wait(); err != nil {
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logrus.Warn(err)
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}
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}
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return nil
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}
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