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spec_opts_unix.go
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spec_opts_unix.go
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// +build !windows
/*
Copyright The containerd Authors.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package oci
import (
"context"
"encoding/json"
"fmt"
"os"
"path/filepath"
"strconv"
"strings"
"github.com/containerd/containerd/containers"
"github.com/containerd/containerd/content"
"github.com/containerd/containerd/images"
"github.com/containerd/containerd/mount"
"github.com/containerd/containerd/namespaces"
"github.com/containerd/continuity/fs"
"github.com/opencontainers/image-spec/specs-go/v1"
"github.com/opencontainers/runc/libcontainer/user"
specs "github.com/opencontainers/runtime-spec/specs-go"
"github.com/pkg/errors"
"github.com/syndtr/gocapability/capability"
)
// WithTTY sets the information on the spec as well as the environment variables for
// using a TTY
func WithTTY(_ context.Context, _ Client, _ *containers.Container, s *specs.Spec) error {
s.Process.Terminal = true
s.Process.Env = append(s.Process.Env, "TERM=xterm")
return nil
}
// WithHostNamespace allows a task to run inside the host's linux namespace
func WithHostNamespace(ns specs.LinuxNamespaceType) SpecOpts {
return func(_ context.Context, _ Client, _ *containers.Container, s *specs.Spec) error {
for i, n := range s.Linux.Namespaces {
if n.Type == ns {
s.Linux.Namespaces = append(s.Linux.Namespaces[:i], s.Linux.Namespaces[i+1:]...)
return nil
}
}
return nil
}
}
// WithLinuxNamespace uses the passed in namespace for the spec. If a namespace of the same type already exists in the
// spec, the existing namespace is replaced by the one provided.
func WithLinuxNamespace(ns specs.LinuxNamespace) SpecOpts {
return func(_ context.Context, _ Client, _ *containers.Container, s *specs.Spec) error {
for i, n := range s.Linux.Namespaces {
if n.Type == ns.Type {
before := s.Linux.Namespaces[:i]
after := s.Linux.Namespaces[i+1:]
s.Linux.Namespaces = append(before, ns)
s.Linux.Namespaces = append(s.Linux.Namespaces, after...)
return nil
}
}
s.Linux.Namespaces = append(s.Linux.Namespaces, ns)
return nil
}
}
// WithImageConfig configures the spec to from the configuration of an Image
func WithImageConfig(image Image) SpecOpts {
return func(ctx context.Context, client Client, c *containers.Container, s *specs.Spec) error {
ic, err := image.Config(ctx)
if err != nil {
return err
}
var (
ociimage v1.Image
config v1.ImageConfig
)
switch ic.MediaType {
case v1.MediaTypeImageConfig, images.MediaTypeDockerSchema2Config:
p, err := content.ReadBlob(ctx, image.ContentStore(), ic.Digest)
if err != nil {
return err
}
if err := json.Unmarshal(p, &ociimage); err != nil {
return err
}
config = ociimage.Config
default:
return fmt.Errorf("unknown image config media type %s", ic.MediaType)
}
if s.Process == nil {
s.Process = &specs.Process{}
}
s.Process.Env = append(s.Process.Env, config.Env...)
cmd := config.Cmd
s.Process.Args = append(config.Entrypoint, cmd...)
cwd := config.WorkingDir
if cwd == "" {
cwd = "/"
}
s.Process.Cwd = cwd
if config.User != "" {
// According to OCI Image Spec v1.0.0, the following are valid for Linux:
// user, uid, user:group, uid:gid, uid:group, user:gid
parts := strings.Split(config.User, ":")
switch len(parts) {
case 1:
v, err := strconv.Atoi(parts[0])
if err != nil {
// if we cannot parse as a uint they try to see if it is a username
return WithUsername(config.User)(ctx, client, c, s)
}
return WithUserID(uint32(v))(ctx, client, c, s)
case 2:
// TODO: support username and groupname
v, err := strconv.Atoi(parts[0])
if err != nil {
return errors.Wrapf(err, "parse uid %s", parts[0])
}
uid := uint32(v)
if v, err = strconv.Atoi(parts[1]); err != nil {
return errors.Wrapf(err, "parse gid %s", parts[1])
}
gid := uint32(v)
s.Process.User.UID, s.Process.User.GID = uid, gid
default:
return fmt.Errorf("invalid USER value %s", config.User)
}
}
return nil
}
}
// WithRootFSPath specifies unmanaged rootfs path.
func WithRootFSPath(path string) SpecOpts {
return func(_ context.Context, _ Client, _ *containers.Container, s *specs.Spec) error {
if s.Root == nil {
s.Root = &specs.Root{}
}
s.Root.Path = path
// Entrypoint is not set here (it's up to caller)
return nil
}
}
// WithRootFSReadonly sets specs.Root.Readonly to true
func WithRootFSReadonly() SpecOpts {
return func(_ context.Context, _ Client, _ *containers.Container, s *specs.Spec) error {
if s.Root == nil {
s.Root = &specs.Root{}
}
s.Root.Readonly = true
return nil
}
}
// WithNoNewPrivileges sets no_new_privileges on the process for the container
func WithNoNewPrivileges(_ context.Context, _ Client, _ *containers.Container, s *specs.Spec) error {
s.Process.NoNewPrivileges = true
return nil
}
// WithHostHostsFile bind-mounts the host's /etc/hosts into the container as readonly
func WithHostHostsFile(_ context.Context, _ Client, _ *containers.Container, s *specs.Spec) error {
s.Mounts = append(s.Mounts, specs.Mount{
Destination: "/etc/hosts",
Type: "bind",
Source: "/etc/hosts",
Options: []string{"rbind", "ro"},
})
return nil
}
// WithHostResolvconf bind-mounts the host's /etc/resolv.conf into the container as readonly
func WithHostResolvconf(_ context.Context, _ Client, _ *containers.Container, s *specs.Spec) error {
s.Mounts = append(s.Mounts, specs.Mount{
Destination: "/etc/resolv.conf",
Type: "bind",
Source: "/etc/resolv.conf",
Options: []string{"rbind", "ro"},
})
return nil
}
// WithHostLocaltime bind-mounts the host's /etc/localtime into the container as readonly
func WithHostLocaltime(_ context.Context, _ Client, _ *containers.Container, s *specs.Spec) error {
s.Mounts = append(s.Mounts, specs.Mount{
Destination: "/etc/localtime",
Type: "bind",
Source: "/etc/localtime",
Options: []string{"rbind", "ro"},
})
return nil
}
// WithUserNamespace sets the uid and gid mappings for the task
// this can be called multiple times to add more mappings to the generated spec
func WithUserNamespace(container, host, size uint32) SpecOpts {
return func(_ context.Context, _ Client, _ *containers.Container, s *specs.Spec) error {
var hasUserns bool
for _, ns := range s.Linux.Namespaces {
if ns.Type == specs.UserNamespace {
hasUserns = true
break
}
}
if !hasUserns {
s.Linux.Namespaces = append(s.Linux.Namespaces, specs.LinuxNamespace{
Type: specs.UserNamespace,
})
}
mapping := specs.LinuxIDMapping{
ContainerID: container,
HostID: host,
Size: size,
}
s.Linux.UIDMappings = append(s.Linux.UIDMappings, mapping)
s.Linux.GIDMappings = append(s.Linux.GIDMappings, mapping)
return nil
}
}
// WithCgroup sets the container's cgroup path
func WithCgroup(path string) SpecOpts {
return func(_ context.Context, _ Client, _ *containers.Container, s *specs.Spec) error {
s.Linux.CgroupsPath = path
return nil
}
}
// WithNamespacedCgroup uses the namespace set on the context to create a
// root directory for containers in the cgroup with the id as the subcgroup
func WithNamespacedCgroup() SpecOpts {
return func(ctx context.Context, _ Client, c *containers.Container, s *specs.Spec) error {
namespace, err := namespaces.NamespaceRequired(ctx)
if err != nil {
return err
}
s.Linux.CgroupsPath = filepath.Join("/", namespace, c.ID)
return nil
}
}
// WithUIDGID allows the UID and GID for the Process to be set
func WithUIDGID(uid, gid uint32) SpecOpts {
return func(_ context.Context, _ Client, _ *containers.Container, s *specs.Spec) error {
s.Process.User.UID = uid
s.Process.User.GID = gid
return nil
}
}
// WithUserID sets the correct UID and GID for the container based
// on the image's /etc/passwd contents. If /etc/passwd does not exist,
// or uid is not found in /etc/passwd, it sets gid to be the same with
// uid, and not returns error.
func WithUserID(uid uint32) SpecOpts {
return func(ctx context.Context, client Client, c *containers.Container, s *specs.Spec) (err error) {
if c.Snapshotter == "" && c.SnapshotKey == "" {
if !isRootfsAbs(s.Root.Path) {
return errors.Errorf("rootfs absolute path is required")
}
uuid, ugid, err := getUIDGIDFromPath(s.Root.Path, func(u user.User) bool {
return u.Uid == int(uid)
})
if err != nil {
if os.IsNotExist(err) || err == errNoUsersFound {
s.Process.User.UID, s.Process.User.GID = uid, uid
return nil
}
return err
}
s.Process.User.UID, s.Process.User.GID = uuid, ugid
return nil
}
if c.Snapshotter == "" {
return errors.Errorf("no snapshotter set for container")
}
if c.SnapshotKey == "" {
return errors.Errorf("rootfs snapshot not created for container")
}
snapshotter := client.SnapshotService(c.Snapshotter)
mounts, err := snapshotter.Mounts(ctx, c.SnapshotKey)
if err != nil {
return err
}
return mount.WithTempMount(ctx, mounts, func(root string) error {
uuid, ugid, err := getUIDGIDFromPath(root, func(u user.User) bool {
return u.Uid == int(uid)
})
if err != nil {
if os.IsNotExist(err) || err == errNoUsersFound {
s.Process.User.UID, s.Process.User.GID = uid, uid
return nil
}
return err
}
s.Process.User.UID, s.Process.User.GID = uuid, ugid
return nil
})
}
}
// WithUsername sets the correct UID and GID for the container
// based on the the image's /etc/passwd contents. If /etc/passwd
// does not exist, or the username is not found in /etc/passwd,
// it returns error.
func WithUsername(username string) SpecOpts {
return func(ctx context.Context, client Client, c *containers.Container, s *specs.Spec) (err error) {
if c.Snapshotter == "" && c.SnapshotKey == "" {
if !isRootfsAbs(s.Root.Path) {
return errors.Errorf("rootfs absolute path is required")
}
uid, gid, err := getUIDGIDFromPath(s.Root.Path, func(u user.User) bool {
return u.Name == username
})
if err != nil {
return err
}
s.Process.User.UID, s.Process.User.GID = uid, gid
return nil
}
if c.Snapshotter == "" {
return errors.Errorf("no snapshotter set for container")
}
if c.SnapshotKey == "" {
return errors.Errorf("rootfs snapshot not created for container")
}
snapshotter := client.SnapshotService(c.Snapshotter)
mounts, err := snapshotter.Mounts(ctx, c.SnapshotKey)
if err != nil {
return err
}
return mount.WithTempMount(ctx, mounts, func(root string) error {
uid, gid, err := getUIDGIDFromPath(root, func(u user.User) bool {
return u.Name == username
})
if err != nil {
return err
}
s.Process.User.UID, s.Process.User.GID = uid, gid
return nil
})
}
}
// WithAllCapabilities set all linux capabilities for the process
func WithAllCapabilities(_ context.Context, _ Client, _ *containers.Container, s *specs.Spec) error {
caps := getAllCapabilities()
s.Process.Capabilities.Bounding = caps
s.Process.Capabilities.Effective = caps
s.Process.Capabilities.Permitted = caps
s.Process.Capabilities.Inheritable = caps
return nil
}
func getAllCapabilities() []string {
last := capability.CAP_LAST_CAP
// hack for RHEL6 which has no /proc/sys/kernel/cap_last_cap
if last == capability.Cap(63) {
last = capability.CAP_BLOCK_SUSPEND
}
var caps []string
for _, cap := range capability.List() {
if cap > last {
continue
}
caps = append(caps, "CAP_"+strings.ToUpper(cap.String()))
}
return caps
}
var errNoUsersFound = errors.New("no users found")
func getUIDGIDFromPath(root string, filter func(user.User) bool) (uid, gid uint32, err error) {
ppath, err := fs.RootPath(root, "/etc/passwd")
if err != nil {
return 0, 0, err
}
f, err := os.Open(ppath)
if err != nil {
return 0, 0, err
}
defer f.Close()
users, err := user.ParsePasswdFilter(f, filter)
if err != nil {
return 0, 0, err
}
if len(users) == 0 {
return 0, 0, errNoUsersFound
}
u := users[0]
return uint32(u.Uid), uint32(u.Gid), nil
}
func isRootfsAbs(root string) bool {
return filepath.IsAbs(root)
}