docker/secrets-0002-SUSE-implement-SUSE-container-secrets.patch

From 229a891b45b996a2cd10f5a71541d124e884556e Mon Sep 17 00:00:00 2001
From: Aleksa Sarai <asarai@suse.de>
Date: Wed, 8 Mar 2017 11:43:29 +1100
Subject: [PATCH 2/2] SUSE: implement SUSE container secrets

This allows for us to pass in host credentials to a container, allowing
for SUSEConnect to work with containers.

THIS PATCH IS NOT TO BE UPSTREAMED, DUE TO THE FACT THAT IT IS
SUSE-SPECIFIC, AND UPSTREAM DOES NOT APPROVE OF THIS CONCEPT BECAUSE IT
MAKES BUILDS NOT ENTIRELY REPRODUCIBLE.

SUSE-Bugs: bsc#1057743 bsc#1055676 bsc#1030702
Signed-off-by: Aleksa Sarai <asarai@suse.de>
---
 components/engine/daemon/start.go        |   5 +
 components/engine/daemon/suse_secrets.go | 396 +++++++++++++++++++++++
 2 files changed, 401 insertions(+)
 create mode 100644 components/engine/daemon/suse_secrets.go

diff --git a/components/engine/daemon/start.go b/components/engine/daemon/start.go
index c00bd9ceb22b..aa705888df39 100644
--- a/components/engine/daemon/start.go
+++ b/components/engine/daemon/start.go
@@ -151,6 +151,11 @@ func (daemon *Daemon) containerStart(container *container.Container, checkpoint
 		return err
 	}
 
+	// SUSE:secrets -- inject the SUSE secret store
+	if err := daemon.injectSuseSecretStore(container); err != nil {
+		return errdefs.System(err)
+	}
+
 	spec, err := daemon.createSpec(container)
 	if err != nil {
 		return errdefs.System(err)
diff --git a/components/engine/daemon/suse_secrets.go b/components/engine/daemon/suse_secrets.go
new file mode 100644
index 000000000000..087c877015a7
--- /dev/null
+++ b/components/engine/daemon/suse_secrets.go
@@ -0,0 +1,396 @@
+/*
+ * suse-secrets: patch for Docker to implement SUSE secrets
+ * Copyright (C) 2017 SUSE LLC.
+ *
+ * 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 daemon
+
+import (
+	"archive/tar"
+	"bytes"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strings"
+	"syscall"
+
+	"github.com/docker/docker/container"
+	"github.com/docker/docker/pkg/archive"
+	"github.com/docker/docker/pkg/idtools"
+	"github.com/opencontainers/go-digest"
+	"github.com/sirupsen/logrus"
+
+	swarmtypes "github.com/docker/docker/api/types/swarm"
+	swarmexec "github.com/docker/swarmkit/agent/exec"
+	swarmapi "github.com/docker/swarmkit/api"
+)
+
+func init() {
+	// Output to tell us in logs that SUSE:secrets is enabled.
+	logrus.Infof("SUSE:secrets :: enabled")
+}
+
+// Creating a fake file.
+type SuseFakeFile struct {
+	Path string
+	Uid  int
+	Gid  int
+	Mode os.FileMode
+	Data []byte
+}
+
+func (s SuseFakeFile) id() string {
+	// NOTE: It is _very_ important that this string always has a prefix of
+	//       "suse". This is how we can ensure that we can operate on
+	//       SecretReferences with a confidence that it was made by us.
+	return fmt.Sprintf("suse_%s_%s", digest.FromBytes(s.Data).Hex(), s.Path)
+}
+
+func (s SuseFakeFile) toSecret() *swarmapi.Secret {
+	return &swarmapi.Secret{
+		ID:       s.id(),
+		Internal: true,
+		Spec: swarmapi.SecretSpec{
+			Data: s.Data,
+		},
+	}
+}
+
+func (s SuseFakeFile) toSecretReference(idMaps *idtools.IdentityMapping) *swarmtypes.SecretReference {
+	// Figure out the host-facing {uid,gid} based on the provided maps. Fall
+	// back to root if the UID/GID don't match (we are guaranteed that root is
+	// mapped).
+	ctrUser := idtools.Identity{UID: s.Uid, GID: s.Gid}
+	hostUser := idMaps.RootPair()
+	if user, err := idMaps.ToHost(ctrUser); err == nil {
+		hostUser = user
+	}
+
+	// Return the secret reference as a file target.
+	return &swarmtypes.SecretReference{
+		SecretID:   s.id(),
+		SecretName: s.id(),
+		File: &swarmtypes.SecretReferenceFileTarget{
+			Name: s.Path,
+			UID:  fmt.Sprintf("%d", hostUser.UID),
+			GID:  fmt.Sprintf("%d", hostUser.GID),
+			Mode: s.Mode,
+		},
+	}
+}
+
+// readDir will recurse into a directory prefix/dir, and return the set of
+// secrets in that directory (as a tar archive that is packed inside the "data"
+// field). The Path attribute of each has the prefix stripped. Symlinks are
+// dereferenced.
+func readDir(prefix, dir string) ([]*SuseFakeFile, error) {
+	var suseFiles []*SuseFakeFile
+
+	path := filepath.Join(prefix, dir)
+	fi, err := os.Stat(path)
+	if err != nil {
+		// Ignore dangling symlinks.
+		if os.IsNotExist(err) {
+			logrus.Warnf("SUSE:secrets :: dangling symlink: %s", path)
+			return nil, nil
+		}
+		return nil, err
+	} else if !fi.IsDir() {
+		// Just to be safe.
+		logrus.Warnf("SUSE:secrets :: expected %q to be a directory, but was a file", path)
+		return readFile(prefix, dir)
+	}
+	path, err = filepath.EvalSymlinks(path)
+	if err != nil {
+		return nil, err
+	}
+
+	// Construct a tar archive of the source directory. We tar up the prefix
+	// directory and add dir as an IncludeFiles specifically so that we
+	// preserve the name of the directory itself.
+	tarStream, err := archive.TarWithOptions(path, &archive.TarOptions{
+		Compression:      archive.Uncompressed,
+		IncludeSourceDir: true,
+	})
+	if err != nil {
+		return nil, fmt.Errorf("SUSE:secrets :: failed to tar source directory %q: %v", path, err)
+	}
+	tarStreamBytes, err := ioutil.ReadAll(tarStream)
+	if err != nil {
+		return nil, fmt.Errorf("SUSE:secrets :: failed to read full tar archive: %v", err)
+	}
+
+	// Get a list of the symlinks in the tar archive.
+	var symlinks []string
+	tmpTr := tar.NewReader(bytes.NewBuffer(tarStreamBytes))
+	for {
+		hdr, err := tmpTr.Next()
+		if err == io.EOF {
+			break
+		}
+		if err != nil {
+			return nil, fmt.Errorf("SUSE:secrets :: failed to read through tar reader: %v", err)
+		}
+		if hdr.Typeflag == tar.TypeSymlink {
+			symlinks = append(symlinks, hdr.Name)
+		}
+	}
+
+	// Symlinks aren't dereferenced in the above archive, so we explicitly do a
+	// rewrite of the tar archive to include all symlinks to files. We cannot
+	// do directories here, but lower-level directory symlinks aren't supported
+	// by zypper so this isn't an issue.
+	symlinkModifyMap := map[string]archive.TarModifierFunc{}
+	for _, sym := range symlinks {
+		logrus.Debugf("SUSE:secrets: archive(%q) %q is a need-to-rewrite symlink", path, sym)
+		symlinkModifyMap[sym] = func(tarPath string, hdr *tar.Header, r io.Reader) (*tar.Header, []byte, error) {
+			logrus.Debugf("SUSE:secrets: archive(%q) mapping for symlink %q", path, tarPath)
+			tarFullPath := filepath.Join(path, tarPath)
+
+			// Get a copy of the original byte stream.
+			oldContent, err := ioutil.ReadAll(r)
+			if err != nil {
+				return nil, nil, fmt.Errorf("suse_rewrite: failed to read archive entry %q: %v", tarPath, err)
+			}
+
+			// Check that the file actually exists.
+			fi, err := os.Stat(tarFullPath)
+			if err != nil {
+				logrus.Warnf("suse_rewrite: failed to stat archive entry %q: %v", tarFullPath, err)
+				return hdr, oldContent, nil
+			}
+
+			// Read the actual contents.
+			content, err := ioutil.ReadFile(tarFullPath)
+			if err != nil {
+				logrus.Warnf("suse_rewrite: failed to read %q: %v", tarFullPath, err)
+				return hdr, oldContent, nil
+			}
+
+			newHdr, err := tar.FileInfoHeader(fi, "")
+			if err != nil {
+				// Fake the header.
+				newHdr = &tar.Header{
+					Typeflag: tar.TypeReg,
+					Mode:     0644,
+				}
+			}
+
+			// Update the key fields.
+			hdr.Typeflag = newHdr.Typeflag
+			hdr.Mode = newHdr.Mode
+			hdr.Linkname = ""
+			return hdr, content, nil
+		}
+	}
+
+	// Create the rewritten tar stream.
+	tarStream = archive.ReplaceFileTarWrapper(ioutil.NopCloser(bytes.NewBuffer(tarStreamBytes)), symlinkModifyMap)
+	tarStreamBytes, err = ioutil.ReadAll(tarStream)
+	if err != nil {
+		return nil, fmt.Errorf("SUSE:secrets :: failed to read rewritten archive: %v", err)
+	}
+
+	// Add the tar stream as a "file".
+	suseFiles = append(suseFiles, &SuseFakeFile{
+		Path: dir,
+		Mode: fi.Mode(),
+		Data: tarStreamBytes,
+	})
+	return suseFiles, nil
+}
+
+// readFile returns a secret given a file under a given prefix.
+func readFile(prefix, file string) ([]*SuseFakeFile, error) {
+	path := filepath.Join(prefix, file)
+	fi, err := os.Stat(path)
+	if err != nil {
+		// Ignore dangling symlinks.
+		if os.IsNotExist(err) {
+			logrus.Warnf("SUSE:secrets :: dangling symlink: %s", path)
+			return nil, nil
+		}
+		return nil, err
+	} else if fi.IsDir() {
+		// Just to be safe.
+		logrus.Warnf("SUSE:secrets :: expected %q to be a file, but was a directory", path)
+		return readDir(prefix, file)
+	}
+
+	stat, ok := fi.Sys().(*syscall.Stat_t)
+	if !ok {
+		logrus.Warnf("SUSE:secrets :: failed to cast file stat_t: defaulting to owned by root:root: %s", path)
+	}
+
+	bytes, err := ioutil.ReadFile(path)
+	if err != nil {
+		return nil, err
+	}
+
+	var suseFiles []*SuseFakeFile
+	suseFiles = append(suseFiles, &SuseFakeFile{
+		Path: file,
+		Uid:  int(stat.Uid),
+		Gid:  int(stat.Gid),
+		Mode: fi.Mode(),
+		Data: bytes,
+	})
+	return suseFiles, nil
+}
+
+// getHostSuseSecretData returns the list of SuseFakeFiles the need to be added
+// as SUSE secrets.
+func getHostSuseSecretData() ([]*SuseFakeFile, error) {
+	secrets := []*SuseFakeFile{}
+
+	credentials, err := readDir("/etc/zypp", "credentials.d")
+	if err != nil {
+		if os.IsNotExist(err) {
+			credentials = []*SuseFakeFile{}
+		} else {
+			logrus.Errorf("SUSE:secrets :: error while reading zypp credentials: %s", err)
+			return nil, err
+		}
+	}
+	secrets = append(secrets, credentials...)
+
+	suseConnect, err := readFile("/etc", "SUSEConnect")
+	if err != nil {
+		if os.IsNotExist(err) {
+			suseConnect = []*SuseFakeFile{}
+		} else {
+			logrus.Errorf("SUSE:secrets :: error while reading /etc/SUSEConnect: %s", err)
+			return nil, err
+		}
+	}
+	secrets = append(secrets, suseConnect...)
+
+	return secrets, nil
+}
+
+// To fake an empty store, in the case where we are operating on a container
+// that was created pre-swarmkit. Otherwise segfaults and other fun things
+// happen. See bsc#1057743.
+type (
+	suseEmptyStore  struct{}
+	suseEmptySecret struct{}
+	suseEmptyConfig struct{}
+)
+
+// In order to reduce the amount of code touched outside of this file, we
+// implement the swarm API for DependencyGetter. This asserts that this
+// requirement will always be matched. In addition, for the case of the *empty*
+// getters this reduces memory usage by having a global instance.
+var (
+	_           swarmexec.DependencyGetter = &suseDependencyStore{}
+	emptyStore  swarmexec.DependencyGetter = suseEmptyStore{}
+	emptySecret swarmexec.SecretGetter     = suseEmptySecret{}
+	emptyConfig swarmexec.ConfigGetter     = suseEmptyConfig{}
+)
+
+var errSuseEmptyStore = fmt.Errorf("SUSE:secrets :: tried to get a resource from empty store [this is a bug]")
+
+func (_ suseEmptyConfig) Get(_ string) (*swarmapi.Config, error) { return nil, errSuseEmptyStore }
+func (_ suseEmptySecret) Get(_ string) (*swarmapi.Secret, error) { return nil, errSuseEmptyStore }
+func (_ suseEmptyStore) Secrets() swarmexec.SecretGetter         { return emptySecret }
+func (_ suseEmptyStore) Configs() swarmexec.ConfigGetter         { return emptyConfig }
+
+type suseDependencyStore struct {
+	dfl     swarmexec.DependencyGetter
+	secrets map[string]*swarmapi.Secret
+}
+
+// The following are effectively dumb wrappers that return ourselves, or the
+// default.
+func (s *suseDependencyStore) Secrets() swarmexec.SecretGetter { return s }
+func (s *suseDependencyStore) Configs() swarmexec.ConfigGetter { return s.dfl.Configs() }
+
+// Get overrides the underlying DependencyGetter with our own secrets (falling
+// through to the underlying DependencyGetter if the secret isn't present).
+func (s *suseDependencyStore) Get(id string) (*swarmapi.Secret, error) {
+	logrus.Debugf("SUSE:secrets :: id=%s requested from suseDependencyGetter", id)
+
+	secret, ok := s.secrets[id]
+	if !ok {
+		// fallthrough
+		return s.dfl.Secrets().Get(id)
+	}
+	return secret, nil
+}
+
+// removeSuseSecrets removes any SecretReferences which were added by us
+// explicitly (this is detected by checking that the prefix has a 'suse'
+// prefix). See bsc#1057743.
+func removeSuseSecrets(c *container.Container) {
+	var without []*swarmtypes.SecretReference
+	for _, secret := range c.SecretReferences {
+		if strings.HasPrefix(secret.SecretID, "suse") {
+			logrus.Warnf("SUSE:secrets :: removing 'old' suse secret %q from container %q", secret.SecretID, c.ID)
+			continue
+		}
+		without = append(without, secret)
+	}
+	c.SecretReferences = without
+}
+
+func (daemon *Daemon) injectSuseSecretStore(c *container.Container) error {
+	newDependencyStore := &suseDependencyStore{
+		dfl:     c.DependencyStore,
+		secrets: make(map[string]*swarmapi.Secret),
+	}
+	// Handle old containers. See bsc#1057743.
+	if newDependencyStore.dfl == nil {
+		newDependencyStore.dfl = emptyStore
+	}
+
+	// We drop any "old" SUSE secrets, as it appears that old containers (when
+	// restarted) could still have references to old secrets. The .id() of all
+	// secrets have a prefix of "suse" so this is much easier. See bsc#1057743
+	// for details on why this could cause issues.
+	removeSuseSecrets(c)
+
+	secrets, err := getHostSuseSecretData()
+	if err != nil {
+		return err
+	}
+
+	idMaps := daemon.idMapping
+	for _, secret := range secrets {
+		newDependencyStore.secrets[secret.id()] = secret.toSecret()
+		c.SecretReferences = append(c.SecretReferences, secret.toSecretReference(idMaps))
+	}
+
+	c.DependencyStore = newDependencyStore
+
+	// bsc#1057743 -- In older versions of Docker we added volumes explicitly
+	// to the mount list. This causes clashes because of duplicate namespaces.
+	// If we see an existing mount that will clash with the in-built secrets
+	// mount we assume it's our fault.
+	intendedMounts, err := c.SecretMounts()
+	if err != nil {
+		logrus.Warnf("SUSE:secrets :: fetching old secret mounts: %v", err)
+		return err
+	}
+	for _, intendedMount := range intendedMounts {
+		mountPath := intendedMount.Destination
+		if volume, ok := c.MountPoints[mountPath]; ok {
+			logrus.Debugf("SUSE:secrets :: removing pre-existing %q mount: %#v", mountPath, volume)
+			delete(c.MountPoints, mountPath)
+		}
+	}
+	return nil
+}
-- 
2.19.2