mirror of
https://github.com/containerd/containerd.git
synced 2026-11-06 13:27:16 +00:00
Wei Fu
a8fc3a0172
Some rootfs may use symlinks for /etc/passwd and /etc/group. For example, NixOS uses absolute symlinks to files in /nix/store. os.Root is not used because it rejects absolute symlinks. The previous code only handled a symlink on the final path. Add a helper to resolve symlinks in every path component with fs.ReadLinkFS. Absolute symlinks are resolved from the rootfs, and the final path is still opened with fs.FS. When tracing a path through symbolic links, the maximum number of links that can be followed is [40][1]. [1]: <https://man7.org/linux/man-pages/man7/path_resolution.7.html> Signed-off-by: Wei Fu <fuweid89@gmail.com>
482 lines
13 KiB
Go
482 lines
13 KiB
Go
/*
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Copyright The containerd Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package oci
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import (
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"context"
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"io"
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"os"
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"runtime"
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"strings"
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"testing"
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"github.com/containerd/containerd/v2/core/containers"
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"github.com/containerd/containerd/v2/pkg/namespaces"
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"github.com/containerd/containerd/v2/pkg/testutil"
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"github.com/containerd/continuity/fs/fstest"
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"github.com/moby/sys/user"
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"github.com/opencontainers/runtime-spec/specs-go"
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"github.com/stretchr/testify/require"
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)
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func TestGenerateSpec(t *testing.T) {
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t.Parallel()
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ctx := namespaces.WithNamespace(context.Background(), "testing")
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s, err := GenerateSpec(ctx, nil, &containers.Container{ID: t.Name()})
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if err != nil {
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t.Fatal(err)
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}
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if s == nil {
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t.Fatal("GenerateSpec() returns a nil spec")
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}
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if runtime.GOOS == "linux" {
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// check for matching caps
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defaults := defaultUnixCaps()
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for _, cl := range [][]string{
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s.Process.Capabilities.Bounding,
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s.Process.Capabilities.Permitted,
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s.Process.Capabilities.Effective,
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} {
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for i := range defaults {
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if cl[i] != defaults[i] {
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t.Errorf("cap at %d does not match set %q != %q", i, defaults[i], cl[i])
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}
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}
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}
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// check default namespaces
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defaultNS := defaultUnixNamespaces()
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for i, ns := range s.Linux.Namespaces {
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if defaultNS[i] != ns {
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t.Errorf("ns at %d does not match set %q != %q", i, defaultNS[i], ns)
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}
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}
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} else if runtime.GOOS == "windows" {
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if s.Windows == nil {
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t.Fatal("Windows section of spec not filled in for Windows spec")
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}
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}
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// test that we don't have tty set
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if s.Process.Terminal {
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t.Error("terminal set on default process")
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}
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}
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func TestGenerateSpecWithPlatform(t *testing.T) {
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t.Parallel()
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ctx := namespaces.WithNamespace(context.Background(), "testing")
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platforms := []string{"windows/amd64", "linux/amd64"}
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for _, p := range platforms {
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t.Logf("Testing platform: %s", p)
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s, err := GenerateSpecWithPlatform(ctx, nil, p, &containers.Container{ID: t.Name()})
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if err != nil {
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t.Fatalf("failed to generate spec: %v", err)
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}
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if s.Root == nil {
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t.Fatal("expected non nil Root section.")
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}
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if s.Process == nil {
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t.Fatal("expected non nil Process section.")
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}
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if p == "windows/amd64" {
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if s.Linux != nil {
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t.Fatal("expected nil Linux section")
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}
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if s.Windows == nil {
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t.Fatal("expected non nil Windows section")
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}
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} else {
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if s.Linux == nil {
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t.Fatal("expected non nil Linux section")
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}
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if runtime.GOOS == "windows" && s.Windows == nil {
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t.Fatal("expected non nil Windows section for LCOW")
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} else if runtime.GOOS != "windows" && s.Windows != nil {
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t.Fatal("expected nil Windows section")
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}
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}
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}
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}
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func TestSpecWithTTY(t *testing.T) {
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t.Parallel()
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ctx := namespaces.WithNamespace(context.Background(), "testing")
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s, err := GenerateSpec(ctx, nil, &containers.Container{ID: t.Name()}, WithTTY)
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if err != nil {
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t.Fatal(err)
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}
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if !s.Process.Terminal {
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t.Error("terminal net set WithTTY()")
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}
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if runtime.GOOS == "linux" {
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v := s.Process.Env[len(s.Process.Env)-1]
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if v != "TERM=xterm" {
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t.Errorf("xterm not set in env for TTY")
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}
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} else {
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if len(s.Process.Env) != 0 {
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t.Fatal("Windows process args should be empty by default")
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}
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}
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}
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func TestWithLinuxNamespace(t *testing.T) {
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t.Parallel()
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ctx := namespaces.WithNamespace(context.Background(), "testing")
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replacedNS := specs.LinuxNamespace{Type: specs.NetworkNamespace, Path: "/var/run/netns/test"}
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var s *specs.Spec
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var err error
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if runtime.GOOS != "windows" {
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s, err = GenerateSpec(ctx, nil, &containers.Container{ID: t.Name()}, WithLinuxNamespace(replacedNS))
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} else {
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s, err = GenerateSpecWithPlatform(ctx, nil, "linux/amd64", &containers.Container{ID: t.Name()}, WithLinuxNamespace(replacedNS))
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}
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if err != nil {
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t.Fatal(err)
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}
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defaultNS := defaultUnixNamespaces()
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found := false
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for i, ns := range s.Linux.Namespaces {
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if ns == replacedNS && !found {
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found = true
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continue
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}
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if defaultNS[i] != ns {
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t.Errorf("ns at %d does not match set %q != %q", i, defaultNS[i], ns)
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}
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}
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}
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func TestWithCapabilities(t *testing.T) {
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t.Parallel()
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ctx := namespaces.WithNamespace(context.Background(), "testing")
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opts := []SpecOpts{
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WithCapabilities([]string{"CAP_SYS_ADMIN"}),
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}
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var s *specs.Spec
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var err error
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if runtime.GOOS != "windows" {
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s, err = GenerateSpec(ctx, nil, &containers.Container{ID: t.Name()}, opts...)
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} else {
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s, err = GenerateSpecWithPlatform(ctx, nil, "linux/amd64", &containers.Container{ID: t.Name()}, opts...)
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}
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if err != nil {
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t.Fatal(err)
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}
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if len(s.Process.Capabilities.Bounding) != 1 || s.Process.Capabilities.Bounding[0] != "CAP_SYS_ADMIN" {
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t.Error("Unexpected capabilities set")
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}
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if len(s.Process.Capabilities.Effective) != 1 || s.Process.Capabilities.Effective[0] != "CAP_SYS_ADMIN" {
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t.Error("Unexpected capabilities set")
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}
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if len(s.Process.Capabilities.Permitted) != 1 || s.Process.Capabilities.Permitted[0] != "CAP_SYS_ADMIN" {
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t.Error("Unexpected capabilities set")
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}
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if len(s.Process.Capabilities.Inheritable) != 0 {
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t.Errorf("Unexpected capabilities set: length is non zero (%d)", len(s.Process.Capabilities.Inheritable))
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}
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}
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func TestWithCapabilitiesNil(t *testing.T) {
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t.Parallel()
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ctx := namespaces.WithNamespace(context.Background(), "testing")
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s, err := GenerateSpec(ctx, nil, &containers.Container{ID: t.Name()},
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WithCapabilities(nil),
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)
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if err != nil {
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t.Fatal(err)
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}
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if len(s.Process.Capabilities.Bounding) != 0 {
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t.Errorf("Unexpected capabilities set: length is non zero (%d)", len(s.Process.Capabilities.Bounding))
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}
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if len(s.Process.Capabilities.Effective) != 0 {
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t.Errorf("Unexpected capabilities set: length is non zero (%d)", len(s.Process.Capabilities.Effective))
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}
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if len(s.Process.Capabilities.Permitted) != 0 {
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t.Errorf("Unexpected capabilities set: length is non zero (%d)", len(s.Process.Capabilities.Permitted))
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}
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if len(s.Process.Capabilities.Inheritable) != 0 {
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t.Errorf("Unexpected capabilities set: length is non zero (%d)", len(s.Process.Capabilities.Inheritable))
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}
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}
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func TestPopulateDefaultWindowsSpec(t *testing.T) {
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var (
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c = containers.Container{ID: "TestWithDefaultSpec"}
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ctx = namespaces.WithNamespace(context.Background(), "test")
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)
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var expected Spec
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populateDefaultWindowsSpec(ctx, &expected, c.ID)
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if expected.Windows == nil {
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t.Error("Cannot populate windows Spec")
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}
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}
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func TestPopulateDefaultUnixSpec(t *testing.T) {
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var (
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c = containers.Container{ID: "TestWithDefaultSpec"}
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ctx = namespaces.WithNamespace(context.Background(), "test")
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)
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var expected Spec
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populateDefaultUnixSpec(ctx, &expected, c.ID)
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if expected.Linux == nil {
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t.Error("Cannot populate Unix Spec")
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}
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// CgroupsPath should never contain backslashes when the spec is generated
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// on Windows.
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if strings.Contains(expected.Linux.CgroupsPath, "\\") {
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t.Errorf("CgroupsPath contains backslashes: %s", expected.Linux.CgroupsPath)
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}
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}
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func TestWithPrivileged(t *testing.T) {
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t.Parallel()
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if runtime.GOOS == "linux" {
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// because WithPrivileged depends on CapEff in /proc/self/status
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testutil.RequiresRoot(t)
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}
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ctx := namespaces.WithNamespace(context.Background(), "testing")
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opts := []SpecOpts{
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WithCapabilities(nil),
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WithMounts([]specs.Mount{
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{Type: "cgroup", Destination: "/sys/fs/cgroup", Options: []string{"ro"}},
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}),
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WithPrivileged,
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}
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var s *specs.Spec
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var err error
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if runtime.GOOS != "windows" {
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s, err = GenerateSpec(ctx, nil, &containers.Container{ID: t.Name()}, opts...)
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} else {
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s, err = GenerateSpecWithPlatform(ctx, nil, "linux/amd64", &containers.Container{ID: t.Name()}, opts...)
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}
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if err != nil {
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t.Fatal(err)
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}
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if runtime.GOOS != "linux" {
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return
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}
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if len(s.Process.Capabilities.Bounding) == 0 {
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t.Error("Expected capabilities to be set with privileged")
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}
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var foundSys, foundCgroup bool
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for _, m := range s.Mounts {
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switch m.Type {
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case "sysfs":
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foundSys = true
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var found bool
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for _, o := range m.Options {
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switch o {
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case "ro":
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t.Errorf("Found unexpected read only %s mount", m.Type)
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case "rw":
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found = true
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}
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}
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if !found {
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t.Errorf("Did not find rw mount option for %s", m.Type)
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}
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case "cgroup":
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foundCgroup = true
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var found bool
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for _, o := range m.Options {
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switch o {
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case "ro":
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t.Errorf("Found unexpected read only %s mount", m.Type)
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case "rw":
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found = true
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}
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}
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if !found {
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t.Errorf("Did not find rw mount option for %s", m.Type)
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}
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}
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}
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if !foundSys {
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t.Error("Did not find mount for sysfs")
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}
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if !foundCgroup {
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t.Error("Did not find mount for cgroupfs")
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}
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}
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func TestOpenUserFile_Symlink(t *testing.T) {
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if runtime.GOOS == "windows" {
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t.Skip("symlink handling is only supported on non-Windows platforms")
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}
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expectedContent := []byte("root:x:0:0:root:/root:/bin/bash" + t.Name())
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for _, tc := range []struct {
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name string
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initOps []fstest.Applier
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}{
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{
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name: "absolute symlink - v1",
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initOps: []fstest.Applier{
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fstest.CreateDir("/etc", 0o755),
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fstest.CreateDir("/nix/store/abcd", 0o755),
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fstest.CreateFile("/nix/store/abcd/passwd", expectedContent, 0o644),
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// /etc/passwd -> /nix/store/abcd/passwd (absolute symlink)
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fstest.Symlink("/nix/store/abcd/passwd", "/etc/passwd"),
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},
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},
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{
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name: "absolute symlink - v2",
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initOps: []fstest.Applier{
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fstest.CreateDir("/system/etc", 0o755),
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fstest.CreateFile("/system/etc/passwd", expectedContent, 0o644),
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// /etc -> /system/etc (absolute symlink)
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fstest.Symlink("/system/etc", "/etc"),
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},
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},
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{
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name: "relative symlink - v1",
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initOps: []fstest.Applier{
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fstest.CreateDir("/system/etc", 0o755),
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fstest.CreateFile("/system/etc/passwd", expectedContent, 0o644),
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fstest.Symlink("../system/etc", "/etc"),
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},
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},
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{
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name: "relative symlink - v2",
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initOps: []fstest.Applier{
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fstest.CreateFile("/passwd", expectedContent, 0o644),
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fstest.Symlink("..", "/etc"),
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},
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},
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} {
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t.Run(tc.name, func(t *testing.T) {
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rootDir := t.TempDir()
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err := fstest.Apply(tc.initOps...).Apply(rootDir)
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require.NoError(t, err)
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rootFS, err := os.OpenRoot(rootDir)
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require.NoError(t, err)
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defer rootFS.Close()
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f, err := openUserFile(rootFS.FS(), "etc/passwd")
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require.NoError(t, err)
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defer f.Close()
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content, err := io.ReadAll(f)
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require.NoError(t, err)
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require.Equal(t, string(expectedContent), string(content))
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})
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}
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}
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func TestGroupLookup_Symlink(t *testing.T) {
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if runtime.GOOS == "windows" {
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t.Skip("symlink handling is only supported on non-Windows platforms")
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}
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expectedContent := []byte("dummygroup:x:1001:paulo\n")
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for _, tc := range []struct {
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name string
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initOps []fstest.Applier
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}{
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{
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name: "absolute symlink - v1",
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initOps: []fstest.Applier{
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fstest.CreateDir("/etc", 0o755),
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fstest.CreateDir("/nix/store/abcd", 0o755),
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fstest.CreateFile("/nix/store/abcd/group", expectedContent, 0o644),
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fstest.Symlink("/nix/store/abcd/group", "/etc/group"),
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},
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},
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{
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name: "absolute symlink - v2",
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initOps: []fstest.Applier{
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fstest.CreateDir("/system/etc", 0o755),
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fstest.CreateFile("/system/etc/group", expectedContent, 0o644),
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fstest.Symlink("/system/etc", "/etc"),
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},
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},
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{
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name: "relative symlink - v1",
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initOps: []fstest.Applier{
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fstest.CreateDir("/system/etc", 0o755),
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fstest.CreateFile("/system/etc/group", expectedContent, 0o644),
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fstest.Symlink("../system/etc", "/etc"),
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},
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},
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{
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name: "relative symlink - v2",
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initOps: []fstest.Applier{
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fstest.CreateFile("group", expectedContent, 0o644),
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fstest.Symlink("..", "/etc"),
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},
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},
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} {
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t.Run(tc.name, func(t *testing.T) {
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rootDir := t.TempDir()
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err := fstest.Apply(tc.initOps...).Apply(rootDir)
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require.NoError(t, err)
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rootFS, err := os.OpenRoot(rootDir)
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require.NoError(t, err)
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defer rootFS.Close()
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gid, err := GIDFromFS(rootFS.FS(), func(g user.Group) bool {
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return g.Name == "dummygroup"
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})
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require.NoError(t, err)
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require.Equal(t, uint32(1001), gid)
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gids, err := getSupplementalGroupsFromFS(rootFS.FS(), func(g user.Group) bool {
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return g.Name == "dummygroup"
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})
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require.NoError(t, err)
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if len(gids) != 1 || gids[0] != 1001 {
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t.Errorf("expected supplemental GIDs [1001], got %v", gids)
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}
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})
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}
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}
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