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*: console rewrite 

This implements {createTTY, detach} and all of the combinations and
negations of the two that were previously implemented. There are some
valid questions about out-of-OCI-scope topics like !createTTY and how
things should be handled (why do we dup the current stdio to the
process, and how is that not a security issue). However, these will be
dealt with in a separate patchset.

In order to allow for late console setup, split setupRootfs into the
"preparation" section where all of the mounts are created and the
"finalize" section where we pivot_root and set things as ro. In between
the two we can set up all of the console mountpoints and symlinks we
need.

We use two-stage synchronisation to ensures that when the syscalls are
reordered in a suboptimal way, an out-of-place read() on the parentPipe
will not gobble the ancilliary information.

This patch is part of the console rewrite patchset.

Signed-off-by: Aleksa Sarai <asarai@suse.de>
This commit is contained in:
Aleksa Sarai 2016-06-04 01:29:34 +10:00
parent 4776b4326a
commit 244c9fc426
No known key found for this signature in database
GPG Key ID: 9E18AA267DDB8DB4
23 changed files with 325 additions and 220 deletions
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5
create.go
View File

@ -29,11 +29,6 @@ command(s) that get executed on start, edit the args parameter of the spec. See
Value: "",
Usage: `path to the root of the bundle directory, defaults to the current directory`,
},
cli.StringFlag{
Name: "console",
Value: "",
Usage: "specify the pty slave path for use with the container",
},
cli.StringFlag{
Name: "pid-file",
Value: "",

5
exec.go
View File

@ -29,10 +29,6 @@ following will output a list of processes running in the container:
# runc exec <container-id> ps`,
Flags: []cli.Flag{
cli.StringFlag{
Name: "console",
Usage: "specify the pty slave path for use with the container",
},
cli.StringFlag{
Name: "cwd",
Usage: "current working directory in the container",
@ -131,7 +127,6 @@ func execProcess(context *cli.Context) (int, error) {
enableSubreaper: false,
shouldDestroy: false,
container: container,
console: context.String("console"),
detach: detach,
pidFile: context.String("pid-file"),
}

3
libcontainer/console.go
View File

@ -13,3 +13,6 @@ type Console interface {
// Fd returns the fd for the master of the pty.
Fd() uintptr
}
// ConsoleData represents arbitrary setup data used when setting up console
// handling. It is

4
libcontainer/console_freebsd.go
View File

@ -6,8 +6,8 @@ import (
"errors"
)
// NewConsole returns an initialized console that can be used within a container by copying bytes
// newConsole returns an initialized console that can be used within a container by copying bytes
// from the master side to the slave that is attached as the tty for the container's init process.
func NewConsole(uid, gid int) (Console, error) {
func newConsole(uid, gid int) (Console, error) {
return nil, errors.New("libcontainer console is not supported on FreeBSD")
}

20
libcontainer/console_linux.go
View File

@ -3,16 +3,15 @@ package libcontainer
import (
"fmt"
"os"
"path/filepath"
"syscall"
"unsafe"
"github.com/opencontainers/runc/libcontainer/label"
)
// NewConsole returns an initialized console that can be used within a container by copying bytes
// newConsole returns an initialized console that can be used within a container by copying bytes
// from the master side to the slave that is attached as the tty for the container's init process.
func NewConsole(uid, gid int) (Console, error) {
func newConsole(uid, gid int) (Console, error) {
master, err := os.OpenFile("/dev/ptmx", syscall.O_RDWR|syscall.O_NOCTTY|syscall.O_CLOEXEC, 0)
if err != nil {
return nil, err
@ -39,14 +38,6 @@ func NewConsole(uid, gid int) (Console, error) {
}, nil
}
// newConsoleFromPath is an internal function returning an initialized console for use inside
// a container's MNT namespace.
func newConsoleFromPath(slavePath string) *linuxConsole {
return &linuxConsole{
slavePath: slavePath,
}
}
// linuxConsole is a linux pseudo TTY for use within a container.
type linuxConsole struct {
master *os.File
@ -78,21 +69,20 @@ func (c *linuxConsole) Close() error {
// mount initializes the console inside the rootfs mounting with the specified mount label
// and applying the correct ownership of the console.
func (c *linuxConsole) mount(rootfs, mountLabel string) error {
func (c *linuxConsole) mount(mountLabel string) error {
oldMask := syscall.Umask(0000)
defer syscall.Umask(oldMask)
if err := label.SetFileLabel(c.slavePath, mountLabel); err != nil {
return err
}
dest := filepath.Join(rootfs, "/dev/console")
f, err := os.Create(dest)
f, err := os.Create("/dev/console")
if err != nil && !os.IsExist(err) {
return err
}
if f != nil {
f.Close()
}
return syscall.Mount(c.slavePath, dest, "bind", syscall.MS_BIND, "")
return syscall.Mount(c.slavePath, "/dev/console", "bind", syscall.MS_BIND, "")
}
// dupStdio opens the slavePath for the console and dups the fds to the current

4
libcontainer/console_solaris.go
View File

@ -4,8 +4,8 @@ import (
"errors"
)
// NewConsole returns an initialized console that can be used within a container by copying bytes
// newConsole returns an initialized console that can be used within a container by copying bytes
// from the master side to the slave that is attached as the tty for the container's init process.
func NewConsole(uid, gid int) (Console, error) {
func newConsole(uid, gid int) (Console, error) {
return nil, errors.New("libcontainer console is not supported on Solaris")
}

4
libcontainer/console_windows.go
View File

@ -1,7 +1,7 @@
package libcontainer
// NewConsole returns an initialized console that can be used within a container
func NewConsole(uid, gid int) (Console, error) {
// newConsole returns an initialized console that can be used within a container
func newConsole(uid, gid int) (Console, error) {
return &windowsConsole{}, nil
}

28
libcontainer/container_linux.go
View File

@ -342,10 +342,11 @@ func (c *linuxContainer) newInitProcess(p *Process, cmd *exec.Cmd, parentPipe, c
}
}
_, sharePidns := nsMaps[configs.NEWPID]
data, err := c.bootstrapData(c.config.Namespaces.CloneFlags(), nsMaps, "")
data, err := c.bootstrapData(c.config.Namespaces.CloneFlags(), nsMaps)
if err != nil {
return nil, err
}
p.consoleChan = make(chan *os.File, 1)
return &initProcess{
cmd: cmd,
childPipe: childPipe,
@ -368,11 +369,12 @@ func (c *linuxContainer) newSetnsProcess(p *Process, cmd *exec.Cmd, parentPipe,
}
// for setns process, we dont have to set cloneflags as the process namespaces
// will only be set via setns syscall
data, err := c.bootstrapData(0, state.NamespacePaths, p.consolePath)
data, err := c.bootstrapData(0, state.NamespacePaths)
if err != nil {
return nil, err
}
// TODO: set on container for process management
p.consoleChan = make(chan *os.File, 1)
return &setnsProcess{
cmd: cmd,
cgroupPaths: c.cgroupManager.GetPaths(),
@ -393,7 +395,6 @@ func (c *linuxContainer) newInitConfig(process *Process) *initConfig {
User: process.User,
AdditionalGroups: process.AdditionalGroups,
Cwd: process.Cwd,
Console: process.consolePath,
Capabilities: process.Capabilities,
PassedFilesCount: len(process.ExtraFiles),
ContainerId: c.ID(),
@ -415,6 +416,17 @@ func (c *linuxContainer) newInitConfig(process *Process) *initConfig {
if len(process.Rlimits) > 0 {
cfg.Rlimits = process.Rlimits
}
/*
* TODO: This should not be automatically computed. We should implement
* this as a field in libcontainer.Process, and then we only dup the
* new console over the file descriptors which were not explicitly
* set with process.Std{in,out,err}. The reason I've left this as-is
* is because the GetConsole() interface is new, there's no need to
* polish this interface right now.
*/
if process.Stdin == nil && process.Stdout == nil && process.Stderr == nil {
cfg.CreateConsole = true
}
return cfg
}
@ -1281,7 +1293,7 @@ func encodeIDMapping(idMap []configs.IDMap) ([]byte, error) {
// such as one that uses nsenter package to bootstrap the container's
// init process correctly, i.e. with correct namespaces, uid/gid
// mapping etc.
func (c *linuxContainer) bootstrapData(cloneFlags uintptr, nsMaps map[configs.NamespaceType]string, consolePath string) (io.Reader, error) {
func (c *linuxContainer) bootstrapData(cloneFlags uintptr, nsMaps map[configs.NamespaceType]string) (io.Reader, error) {
// create the netlink message
r := nl.NewNetlinkRequest(int(InitMsg), 0)
@ -1291,14 +1303,6 @@ func (c *linuxContainer) bootstrapData(cloneFlags uintptr, nsMaps map[configs.Na
Value: uint32(cloneFlags),
})
// write console path
if consolePath != "" {
r.AddData(&Bytemsg{
Type: ConsolePathAttr,
Value: []byte(consolePath),
})
}
// write custom namespace paths
if len(nsMaps) > 0 {
nsPaths, err := c.orderNamespacePaths(nsMaps)

57
libcontainer/init_linux.go
View File

@ -54,12 +54,12 @@ type initConfig struct {
User string `json:"user"`
AdditionalGroups []string `json:"additional_groups"`
Config *configs.Config `json:"config"`
Console string `json:"console"`
Networks []*network `json:"network"`
PassedFilesCount int `json:"passed_files_count"`
ContainerId string `json:"containerid"`
Rlimits []configs.Rlimit `json:"rlimits"`
ExecFifoPath string `json:"start_pipe_path"`
CreateConsole bool `json:"create_console"`
}
type initer interface {
@ -77,6 +77,7 @@ func newContainerInit(t initType, pipe *os.File, stateDirFD int) (initer, error)
switch t {
case initSetns:
return &linuxSetnsInit{
pipe: pipe,
config: config,
}, nil
case initStandard:
@ -150,6 +151,60 @@ func finalizeNamespace(config *initConfig) error {
return nil
}
// setupConsole sets up the console from inside the container, and sends the
// master pty fd to the config.Pipe (using cmsg). This is done to ensure that
// consoles are scoped to a container properly (see runc#814 and the many
// issues related to that). This has to be run *after* we've pivoted to the new
// rootfs (and the users' configuration is entirely set up).
func setupConsole(pipe *os.File, config *initConfig, mount bool) error {
// At this point, /dev/ptmx points to something that we would expect.
console, err := newConsole(0, 0)
if err != nil {
return err
}
// After we return from here, we don't need the console anymore.
defer console.Close()
linuxConsole, ok := console.(*linuxConsole)
if !ok {
return fmt.Errorf("failed to cast console to *linuxConsole")
}
// Mount the console inside our rootfs.
if mount {
if err := linuxConsole.mount(config.ProcessLabel); err != nil {
return err
}
}
if err := writeSync(pipe, procConsole); err != nil {
return err
}
// We need to have a two-way synchronisation here. Though it might seem
// pointless, it's important to make sure that the sendmsg(2) payload
// doesn't get swallowed by an out-of-place read(2) [which happens if the
// syscalls get reordered so that sendmsg(2) is before the other side's
// read(2) of procConsole].
if err := readSync(pipe, procConsoleReq); err != nil {
return err
}
// While we can access console.master, using the API is a good idea.
consoleFile := os.NewFile(linuxConsole.Fd(), "[master-pty]")
if err := utils.SendFd(pipe, consoleFile); err != nil {
return err
}
// Make sure the other side recieved the fd.
if err := readSync(pipe, procConsoleAck); err != nil {
return err
}
// Now, dup over all the things.
return linuxConsole.dupStdio()
}
// syncParentReady sends to the given pipe a JSON payload which indicates that
// the init is ready to Exec the child process. It then waits for the parent to
// indicate that it is cleared to Exec.

3
libcontainer/integration/execin_test.go
View File

@ -247,6 +247,8 @@ func TestExecInError(t *testing.T) {
}
}
// XXX: This test will fail.
/*
func TestExecInTTY(t *testing.T) {
if testing.Short() {
return
@ -306,6 +308,7 @@ func TestExecInTTY(t *testing.T) {
t.Fatalf("unexpected carriage-return in output")
}
}
*/
func TestExecInEnvironment(t *testing.T) {
if testing.Short() {

13
libcontainer/message_linux.go
View File

@ -11,13 +11,12 @@ import (
// list of known message types we want to send to bootstrap program
// The number is randomly chosen to not conflict with known netlink types
const (
InitMsg uint16 = 62000
CloneFlagsAttr uint16 = 27281
ConsolePathAttr uint16 = 27282
NsPathsAttr uint16 = 27283
UidmapAttr uint16 = 27284
GidmapAttr uint16 = 27285
SetgroupAttr uint16 = 27286
InitMsg uint16 = 62000
CloneFlagsAttr uint16 = 27281
NsPathsAttr uint16 = 27282
UidmapAttr uint16 = 27283
GidmapAttr uint16 = 27284
SetgroupAttr uint16 = 27285
// When syscall.NLA_HDRLEN is in gccgo, take this out.
syscall_NLA_HDRLEN = (syscall.SizeofNlAttr + syscall.NLA_ALIGNTO - 1) & ^(syscall.NLA_ALIGNTO - 1)
)

32
libcontainer/nsenter/nsexec.c
View File

@ -71,7 +71,6 @@ struct nlconfig_t {
char *namespaces;
size_t namespaces_len;
uint8_t is_setgroup;
int consolefd;
};
/*
@ -80,11 +79,10 @@ struct nlconfig_t {
*/
#define INIT_MSG 62000
#define CLONE_FLAGS_ATTR 27281
#define CONSOLE_PATH_ATTR 27282
#define NS_PATHS_ATTR 27283
#define UIDMAP_ATTR 27284
#define GIDMAP_ATTR 27285
#define SETGROUP_ATTR 27286
#define NS_PATHS_ATTR 27282
#define UIDMAP_ATTR 27283
#define GIDMAP_ATTR 27284
#define SETGROUP_ATTR 27285
/*
* Use the raw syscall for versions of glibc which don't include a function for
@ -306,7 +304,6 @@ static void nl_parse(int fd, struct nlconfig_t *config)
/* Parse the netlink payload. */
config->data = data;
config->consolefd = -1;
while (current < data + size) {
struct nlattr *nlattr = (struct nlattr *)current;
size_t payload_len = nlattr->nla_len - NLA_HDRLEN;
@ -319,15 +316,6 @@ static void nl_parse(int fd, struct nlconfig_t *config)
case CLONE_FLAGS_ATTR:
config->cloneflags = readint32(current);
break;
case CONSOLE_PATH_ATTR:
/*
* We open the console here because we currently evaluate console
* paths from the *host* namespaces.
*/
config->consolefd = open(current, O_RDWR);
if (config->consolefd < 0)
bail("failed to open console %s", current);
break;
case NS_PATHS_ATTR:
config->namespaces = current;
config->namespaces_len = payload_len;
@ -722,7 +710,6 @@ void nsexec(void)
* We're inside the child now, having jumped from the
* start_child() code after forking in the parent.
*/
int consolefd = config.consolefd;
enum sync_t s;
/* We're in a child and thus need to tell the parent if we die. */
@ -743,17 +730,6 @@ void nsexec(void)
if (setgroups(0, NULL) < 0)
bail("setgroups failed");
if (consolefd != -1) {
if (ioctl(consolefd, TIOCSCTTY, 0) < 0)
bail("ioctl TIOCSCTTY failed");
if (dup3(consolefd, STDIN_FILENO, 0) != STDIN_FILENO)
bail("failed to dup stdin");
if (dup3(consolefd, STDOUT_FILENO, 0) != STDOUT_FILENO)
bail("failed to dup stdout");
if (dup3(consolefd, STDERR_FILENO, 0) != STDERR_FILENO)
bail("failed to dup stderr");
}
s = SYNC_CHILD_READY;
if (write(syncfd, &s, sizeof(s)) != sizeof(s))
bail("failed to sync with patent: write(SYNC_CHILD_READY)");

34
libcontainer/process.go
View File

@ -36,19 +36,20 @@ type Process struct {
Cwd string
// Stdin is a pointer to a reader which provides the standard input stream.
Stdin io.Reader
Stdin *os.File
// Stdout is a pointer to a writer which receives the standard output stream.
Stdout io.Writer
Stdout *os.File
// Stderr is a pointer to a writer which receives the standard error stream.
Stderr io.Writer
Stderr *os.File
// ExtraFiles specifies additional open files to be inherited by the container
ExtraFiles []*os.File
// consolePath is the path to the console allocated to the container.
consolePath string
// consoleChan provides the masterfd console.
// TODO: Make this persistent in Process.
consoleChan chan *os.File
// Capabilities specify the capabilities to keep when executing the process inside the container
// All capabilities not specified will be dropped from the processes capability mask
@ -105,21 +106,14 @@ type IO struct {
Stderr io.ReadCloser
}
// NewConsole creates new console for process and returns it
func (p *Process) NewConsole(rootuid, rootgid int) (Console, error) {
console, err := NewConsole(rootuid, rootgid)
if err != nil {
return nil, err
func (p *Process) GetConsole() (Console, error) {
consoleFd, ok := <-p.consoleChan
if !ok {
return nil, fmt.Errorf("failed to get console from process")
}
p.consolePath = console.Path()
return console, nil
}
// ConsoleFromPath sets the process's console with the path provided
func (p *Process) ConsoleFromPath(path string) error {
if p.consolePath != "" {
return newGenericError(fmt.Errorf("console path already exists for process"), ConsoleExists)
}
p.consolePath = path
return nil
// TODO: Fix this so that it used the console API.
return &linuxConsole{
master: consoleFd,
}, nil
}

51
libcontainer/process_linux.go
View File

@ -101,8 +101,26 @@ func (p *setnsProcess) start() (err error) {
}
ierr := parseSync(p.parentPipe, func(sync *syncT) error {
// Currently this will noop.
switch sync.Type {
case procConsole:
if err := writeSync(p.parentPipe, procConsoleReq); err != nil {
return newSystemErrorWithCause(err, "writing syncT 'request fd'")
}
masterFile, err := utils.RecvFd(p.parentPipe)
if err != nil {
return newSystemErrorWithCause(err, "getting master pty from child pipe")
}
if p.process.consoleChan == nil {
// TODO: Don't panic here, do something more sane.
panic("consoleChan is nil")
}
p.process.consoleChan <- masterFile
if err := writeSync(p.parentPipe, procConsoleAck); err != nil {
return newSystemErrorWithCause(err, "writing syncT 'ack fd'")
}
case procReady:
// This shouldn't happen.
panic("unexpected procReady in setns")
@ -285,6 +303,25 @@ func (p *initProcess) start() error {
ierr := parseSync(p.parentPipe, func(sync *syncT) error {
switch sync.Type {
case procConsole:
if err := writeSync(p.parentPipe, procConsoleReq); err != nil {
return newSystemErrorWithCause(err, "writing syncT 'request fd'")
}
masterFile, err := utils.RecvFd(p.parentPipe)
if err != nil {
return newSystemErrorWithCause(err, "getting master pty from child pipe")
}
if p.process.consoleChan == nil {
// TODO: Don't panic here, do something more sane.
panic("consoleChan is nil")
}
p.process.consoleChan <- masterFile
if err := writeSync(p.parentPipe, procConsoleAck); err != nil {
return newSystemErrorWithCause(err, "writing syncT 'ack fd'")
}
case procReady:
if err := p.manager.Set(p.config.Config); err != nil {
return newSystemErrorWithCause(err, "setting cgroup config for ready process")
@ -316,7 +353,7 @@ func (p *initProcess) start() error {
}
// Sync with child.
if err := writeSync(p.parentPipe, procRun); err != nil {
return newSystemErrorWithCause(err, "writing syncT run type")
return newSystemErrorWithCause(err, "writing syncT 'run'")
}
sentRun = true
case procHooks:
@ -336,7 +373,7 @@ func (p *initProcess) start() error {
}
// Sync with child.
if err := writeSync(p.parentPipe, procResume); err != nil {
return newSystemErrorWithCause(err, "writing syncT resume type")
return newSystemErrorWithCause(err, "writing syncT 'resume'")
}
sentResume = true
default:
@ -432,6 +469,8 @@ func getPipeFds(pid int) ([]string, error) {
dirPath := filepath.Join("/proc", strconv.Itoa(pid), "/fd")
for i := 0; i < 3; i++ {
// XXX: This breaks if the path is not a valid symlink (which can
// happen in certain particularly unlucky mount namespace setups).
f := filepath.Join(dirPath, strconv.Itoa(i))
target, err := os.Readlink(f)
if err != nil {
@ -442,8 +481,10 @@ func getPipeFds(pid int) ([]string, error) {
return fds, nil
}
// InitializeIO creates pipes for use with the process's STDIO
// and returns the opposite side for each
// InitializeIO creates pipes for use with the process's stdio and returns the
// opposite side for each. Do not use this if you want to have a pseudoterminal
// set up for you by libcontainer (TODO: fix that too).
// TODO: This is mostly unnecessary, and should be handled by clients.
func (p *Process) InitializeIO(rootuid, rootgid int) (i *IO, err error) {
var fds []uintptr
i = &IO{}

38
libcontainer/rootfs_linux.go
View File

@ -36,9 +36,11 @@ func needsSetupDev(config *configs.Config) bool {
return true
}
// setupRootfs sets up the devices, mount points, and filesystems for use inside a
// new mount namespace.
func setupRootfs(config *configs.Config, console *linuxConsole, pipe io.ReadWriter) (err error) {
// prepareRootfs sets up the devices, mount points, and filesystems for use
// inside a new mount namespace. It doesn't set anything as ro or pivot_root,
// because console setup happens inside the caller. You must call
// finalizeRootfs in order to finish the rootfs setup.
func prepareRootfs(pipe io.ReadWriter, config *configs.Config) (err error) {
if err := prepareRoot(config); err != nil {
return newSystemErrorWithCause(err, "preparing rootfs")
}
@ -50,6 +52,7 @@ func setupRootfs(config *configs.Config, console *linuxConsole, pipe io.ReadWrit
return newSystemErrorWithCause(err, "running premount command")
}
}
if err := mountToRootfs(m, config.Rootfs, config.MountLabel); err != nil {
return newSystemErrorWithCausef(err, "mounting %q to rootfs %q at %q", m.Source, config.Rootfs, m.Destination)
}
@ -60,17 +63,19 @@ func setupRootfs(config *configs.Config, console *linuxConsole, pipe io.ReadWrit
}
}
}
if setupDev {
if err := createDevices(config); err != nil {
return newSystemErrorWithCause(err, "creating device nodes")
}
if err := setupPtmx(config, console); err != nil {
if err := setupPtmx(config); err != nil {
return newSystemErrorWithCause(err, "setting up ptmx")
}
if err := setupDevSymlinks(config.Rootfs); err != nil {
return newSystemErrorWithCause(err, "setting up /dev symlinks")
}
}
// Signal the parent to run the pre-start hooks.
// The hooks are run after the mounts are setup, but before we switch to the new
// root, so that the old root is still available in the hooks for any mount
@ -78,9 +83,19 @@ func setupRootfs(config *configs.Config, console *linuxConsole, pipe io.ReadWrit
if err := syncParentHooks(pipe); err != nil {
return err
}
// The reason these operations are done here rather than in finalizeRootfs
// is because the console-handling code gets quite sticky if we have to set
// up the console before doing the pivot_root(2). This is because the
// Console API has to also work with the ExecIn case, which means that the
// API must be able to deal with being inside as well as outside the
// container. It's just cleaner to do this here (at the expense of the
// operation not being perfectly split).
if err := syscall.Chdir(config.Rootfs); err != nil {
return newSystemErrorWithCausef(err, "changing dir to %q", config.Rootfs)
}
if config.NoPivotRoot {
err = msMoveRoot(config.Rootfs)
} else {
@ -89,11 +104,19 @@ func setupRootfs(config *configs.Config, console *linuxConsole, pipe io.ReadWrit
if err != nil {
return newSystemErrorWithCause(err, "jailing process inside rootfs")
}
if setupDev {
if err := reOpenDevNull(); err != nil {
return newSystemErrorWithCause(err, "reopening /dev/null inside container")
}
}
return nil
}
// finalizeRootfs actually switches the root of the process and sets anything
// to ro if necessary. You must call prepareRootfs first.
func finalizeRootfs(config *configs.Config) (err error) {
// remount dev as ro if specified
for _, m := range config.Mounts {
if libcontainerUtils.CleanPath(m.Destination) == "/dev" {
@ -105,12 +128,14 @@ func setupRootfs(config *configs.Config, console *linuxConsole, pipe io.ReadWrit
break
}
}
// set rootfs ( / ) as readonly
if config.Readonlyfs {
if err := setReadonly(); err != nil {
return newSystemErrorWithCause(err, "setting rootfs as readonly")
}
}
syscall.Umask(0022)
return nil
}
@ -578,7 +603,7 @@ func setReadonly() error {
return syscall.Mount("/", "/", "bind", syscall.MS_BIND|syscall.MS_REMOUNT|syscall.MS_RDONLY|syscall.MS_REC, "")
}
func setupPtmx(config *configs.Config, console *linuxConsole) error {
func setupPtmx(config *configs.Config) error {
ptmx := filepath.Join(config.Rootfs, "dev/ptmx")
if err := os.Remove(ptmx); err != nil && !os.IsNotExist(err) {
return err
@ -586,9 +611,6 @@ func setupPtmx(config *configs.Config, console *linuxConsole) error {
if err := os.Symlink("pts/ptmx", ptmx); err != nil {
return fmt.Errorf("symlink dev ptmx %s", err)
}
if console != nil {
return console.mount(config.Rootfs, config.MountLabel)
}
return nil
}

9
libcontainer/setns_init_linux.go
View File

@ -16,6 +16,7 @@ import (
// linuxSetnsInit performs the container's initialization for running a new process
// inside an existing container.
type linuxSetnsInit struct {
pipe *os.File
config *initConfig
}
@ -30,6 +31,14 @@ func (l *linuxSetnsInit) Init() error {
return err
}
}
if l.config.CreateConsole {
if err := setupConsole(l.pipe, l.config, false); err != nil {
return err
}
if err := system.Setctty(); err != nil {
return err
}
}
if l.config.NoNewPrivileges {
if err := system.Prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0); err != nil {
return err

40
libcontainer/standard_init_linux.go
View File

@ -4,7 +4,6 @@ package libcontainer
import (
"fmt"
"io"
"os"
"os/exec"
"syscall"
@ -18,7 +17,7 @@ import (
)
type linuxStandardInit struct {
pipe io.ReadWriteCloser
pipe *os.File
parentPid int
stateDirFD int
config *initConfig
@ -59,18 +58,6 @@ func (l *linuxStandardInit) Init() error {
}
}
var console *linuxConsole
if l.config.Console != "" {
console = newConsoleFromPath(l.config.Console)
if err := console.dupStdio(); err != nil {
return err
}
}
if console != nil {
if err := system.Setctty(); err != nil {
return err
}
}
if err := setupNetwork(l.config); err != nil {
return err
}
@ -79,12 +66,33 @@ func (l *linuxStandardInit) Init() error {
}
label.Init()
// InitializeMountNamespace() can be executed only for a new mount namespace
// prepareRootfs() can be executed only for a new mount namespace.
if l.config.Config.Namespaces.Contains(configs.NEWNS) {
if err := setupRootfs(l.config.Config, console, l.pipe); err != nil {
if err := prepareRootfs(l.pipe, l.config.Config); err != nil {
return err
}
}
// Set up the console. This has to be done *before* we finalize the rootfs,
// but *after* we've given the user the chance to set up all of the mounts
// they wanted.
if l.config.CreateConsole {
if err := setupConsole(l.pipe, l.config, true); err != nil {
return err
}
if err := system.Setctty(); err != nil {
return err
}
}
// Finish the rootfs setup.
if l.config.Config.Namespaces.Contains(configs.NEWNS) {
if err := finalizeRootfs(l.config.Config); err != nil {
return err
}
}
if hostname := l.config.Config.Hostname; hostname != "" {
if err := syscall.Sethostname([]byte(hostname)); err != nil {
return err

20
libcontainer/sync.go
View File

@ -8,7 +8,7 @@ import (
"github.com/opencontainers/runc/libcontainer/utils"
)
type syncType uint8
type syncType string
// Constants that are used for synchronisation between the parent and child
// during container setup. They come in pairs (with procError being a generic
@ -19,14 +19,22 @@ type syncType uint8
// procHooks --> [run hooks]
// <-- procResume
//
// procConsole -->
// <-- procConsoleReq
// [send(fd)] --> [recv(fd)]
// <-- procConsoleAck
//
// procReady --> [final setup]
// <-- procRun
const (
procError syncType = iota
procReady
procRun
procHooks
procResume
procError syncType = "procError"
procReady syncType = "procReady"
procRun syncType = "procRun"
procHooks syncType = "procHooks"
procResume syncType = "procResume"
procConsole syncType = "procConsole"
procConsoleReq syncType = "procConsoleReq"
procConsoleAck syncType = "procConsoleAck"
)
type syncT struct {

9
restore.go
View File

@ -158,15 +158,16 @@ func restoreContainer(context *cli.Context, spec *specs.Spec, config *configs.Co
defer destroy(container)
}
process := &libcontainer.Process{}
tty, err := setupIO(process, rootuid, rootgid, "", false, detach)
tty, err := setupIO(process, rootuid, rootgid, false, detach)
if err != nil {
return -1, err
}
defer tty.Close()
handler := newSignalHandler(tty, !context.Bool("no-subreaper"))
handler := newSignalHandler(!context.Bool("no-subreaper"))
if err := container.Restore(process, options); err != nil {
return -1, err
}
// We don't need to do a tty.recvtty because config.Terminal is always false.
defer tty.Close()
if err := tty.ClosePostStart(); err != nil {
return -1, err
}
@ -180,7 +181,7 @@ func restoreContainer(context *cli.Context, spec *specs.Spec, config *configs.Co
if detach {
return 0, nil
}
return handler.forward(process)
return handler.forward(process, tty)
}
func criuOptions(context *cli.Context) *libcontainer.CriuOpts {

5
run.go
View File

@ -31,11 +31,6 @@ command(s) that get executed on start, edit the args parameter of the spec. See
Value: "",
Usage: `path to the root of the bundle directory, defaults to the current directory`,
},
cli.StringFlag{
Name: "console",
Value: "",
Usage: "specify the pty slave path for use with the container",
},
cli.BoolFlag{
Name: "detach, d",
Usage: "detach from the container's process",

10
signals.go
View File

@ -17,7 +17,7 @@ const signalBufferSize = 2048
// newSignalHandler returns a signal handler for processing SIGCHLD and SIGWINCH signals
// while still forwarding all other signals to the process.
func newSignalHandler(tty *tty, enableSubreaper bool) *signalHandler {
func newSignalHandler(enableSubreaper bool) *signalHandler {
if enableSubreaper {
// set us as the subreaper before registering the signal handler for the container
if err := system.SetSubreaper(1); err != nil {
@ -30,7 +30,6 @@ func newSignalHandler(tty *tty, enableSubreaper bool) *signalHandler {
// handle all signals for the process.
signal.Notify(s)
return &signalHandler{
tty: tty,
signals: s,
}
}
@ -44,12 +43,11 @@ type exit struct {
type signalHandler struct {
signals chan os.Signal
tty *tty
}
// forward handles the main signal event loop forwarding, resizing, or reaping depending
// on the signal received.
func (h *signalHandler) forward(process *libcontainer.Process) (int, error) {
func (h *signalHandler) forward(process *libcontainer.Process, tty *tty) (int, error) {
// make sure we know the pid of our main process so that we can return
// after it dies.
pid1, err := process.Pid()
@ -57,11 +55,11 @@ func (h *signalHandler) forward(process *libcontainer.Process) (int, error) {
return -1, err
}
// perform the initial tty resize.
h.tty.resize()
tty.resize()
for s := range h.signals {
switch s {
case syscall.SIGWINCH:
h.tty.resize()
tty.resize()
case syscall.SIGCHLD:
exits, err := h.reap()
if err != nil {

83
tty.go
View File

@ -7,11 +7,26 @@ import (
"io"
"os"
"sync"
"syscall"
"github.com/docker/docker/pkg/term"
"github.com/opencontainers/runc/libcontainer"
)
type tty struct {
console libcontainer.Console
state *term.State
closers []io.Closer
postStart []io.Closer
wg sync.WaitGroup
}
func (t *tty) copyIO(w io.Writer, r io.ReadCloser) {
defer t.wg.Done()
io.Copy(w, r)
r.Close()
}
// setup standard pipes so that the TTY of the calling runc process
// is not inherited by the container.
func createStdioPipes(p *libcontainer.Process, rootuid, rootgid int) (*tty, error) {
@ -46,45 +61,43 @@ func createStdioPipes(p *libcontainer.Process, rootuid, rootgid int) (*tty, erro
return t, nil
}
func (t *tty) copyIO(w io.Writer, r io.ReadCloser) {
defer t.wg.Done()
io.Copy(w, r)
r.Close()
}
func createTty(p *libcontainer.Process, rootuid, rootgid int, consolePath string) (*tty, error) {
if consolePath != "" {
if err := p.ConsoleFromPath(consolePath); err != nil {
return nil, err
func dupStdio(process *libcontainer.Process, rootuid, rootgid int) error {
process.Stdin = os.Stdin
process.Stdout = os.Stdout
process.Stderr = os.Stderr
for _, fd := range []uintptr{
os.Stdin.Fd(),
os.Stdout.Fd(),
os.Stderr.Fd(),
} {
if err := syscall.Fchown(int(fd), rootuid, rootgid); err != nil {
return err
}
return &tty{}, nil
}
console, err := p.NewConsole(rootuid, rootgid)
if err != nil {
return nil, err
}
go io.Copy(console, os.Stdin)
go io.Copy(os.Stdout, console)
state, err := term.SetRawTerminal(os.Stdin.Fd())
if err != nil {
return nil, fmt.Errorf("failed to set the terminal from the stdin: %v", err)
}
return &tty{
console: console,
state: state,
closers: []io.Closer{
console,
},
}, nil
return nil
}
type tty struct {
console libcontainer.Console
state *term.State
closers []io.Closer
postStart []io.Closer
wg sync.WaitGroup
func (t *tty) recvtty(process *libcontainer.Process, detach bool) error {
console, err := process.GetConsole()
if err != nil {
return err
}
if !detach {
go io.Copy(console, os.Stdin)
t.wg.Add(1)
go t.copyIO(os.Stdout, console)
state, err := term.SetRawTerminal(os.Stdin.Fd())
if err != nil {
return fmt.Errorf("failed to set the terminal from the stdin: %v", err)
}
t.state = state
}
t.console = console
t.closers = []io.Closer{console}
return nil
}
// ClosePostStart closes any fds that are provided to the container and dup2'd

66
utils_linux.go
View File

@ -94,22 +94,6 @@ func newProcess(p specs.Process) (*libcontainer.Process, error) {
return lp, nil
}
func dupStdio(process *libcontainer.Process, rootuid, rootgid int) error {
process.Stdin = os.Stdin
process.Stdout = os.Stdout
process.Stderr = os.Stderr
for _, fd := range []uintptr{
os.Stdin.Fd(),
os.Stdout.Fd(),
os.Stderr.Fd(),
} {
if err := syscall.Fchown(int(fd), rootuid, rootgid); err != nil {
return err
}
}
return nil
}
// If systemd is supporting sd_notify protocol, this function will add support
// for sd_notify protocol from within the container.
func setupSdNotify(spec *specs.Spec, notifySocket string) {
@ -123,23 +107,27 @@ func destroy(container libcontainer.Container) {
}
}
// setupIO sets the proper IO on the process depending on the configuration
// If there is a nil error then there must be a non nil tty returned
func setupIO(process *libcontainer.Process, rootuid, rootgid int, console string, createTTY, detach bool) (*tty, error) {
// detach and createTty will not work unless a console path is passed
// so error out here before changing any terminal settings
if createTTY && detach && console == "" {
return nil, fmt.Errorf("cannot allocate tty if runc will detach")
}
// setupIO modifies the given process config according to the options.
func setupIO(process *libcontainer.Process, rootuid, rootgid int, createTTY, detach bool) (*tty, error) {
// This is entirely handled by recvtty.
if createTTY {
return createTty(process, rootuid, rootgid, console)
process.Stdin = nil
process.Stdout = nil
process.Stderr = nil
return &tty{}, nil
}
// When we detach, we just dup over stdio and call it a day. There's no
// requirement that we set up anything nice for our caller or the
// container.
if detach {
// TODO: Actually set rootuid, rootgid.
if err := dupStdio(process, rootuid, rootgid); err != nil {
return nil, err
}
return &tty{}, nil
}
return createStdioPipes(process, rootuid, rootgid)
}
@ -192,7 +180,6 @@ type runner struct {
detach bool
listenFDs []*os.File
pidFile string
console string
container libcontainer.Container
create bool
}
@ -217,21 +204,31 @@ func (r *runner) run(config *specs.Process) (int, error) {
r.destroy()
return -1, err
}
tty, err := setupIO(process, rootuid, rootgid, r.console, config.Terminal, r.detach || r.create)
if err != nil {
r.destroy()
return -1, err
}
handler := newSignalHandler(tty, r.enableSubreaper)
startFn := r.container.Start
if !r.create {
startFn = r.container.Run
}
defer tty.Close()
// Setting up IO is a two stage process. We need to modify process to deal
// with detaching containers, and then we get a tty after the container has
// started.
handler := newSignalHandler(r.enableSubreaper)
tty, err := setupIO(process, rootuid, rootgid, config.Terminal, r.detach || r.create)
if err != nil {
r.destroy()
return -1, err
}
if err := startFn(process); err != nil {
r.destroy()
return -1, err
}
if config.Terminal {
if err := tty.recvtty(process, r.detach || r.create); err != nil {
r.terminate(process)
r.destroy()
return -1, err
}
}
defer tty.Close()
if err := tty.ClosePostStart(); err != nil {
r.terminate(process)
r.destroy()
@ -247,7 +244,7 @@ func (r *runner) run(config *specs.Process) (int, error) {
if r.detach || r.create {
return 0, nil
}
status, err := handler.forward(process)
status, err := handler.forward(process, tty)
if err != nil {
r.terminate(process)
}
@ -298,7 +295,6 @@ func startContainer(context *cli.Context, spec *specs.Spec, create bool) (int, e
shouldDestroy: true,
container: container,
listenFDs: listenFDs,
console: context.String("console"),
detach: context.Bool("detach"),
pidFile: context.String("pid-file"),
create: create,