[Elastic Agent] Harden permissions and remove encrypted store (elasti…

…c#19678)

* Harden permissions, remove encrypted store.

* Add changelog.

* Fix issues with DiskStore error handling.

(cherry picked from commit b8c49e0)

x-pack/elastic-agent/CHANGELOG.asciidoc

@@ -11,6 +11,7 @@
 ==== Breaking changes
 - Rename agent to elastic-agent {pull}17391[17391]
 - Change fleet.yml structure, causes upgraded agent to register as new agent {pull}19248[19248]
+- Remove obfuscation of fleet.yml, causes re-enroll of agent to Fleet {pull}19678[19678]
 
 ==== Bugfixes
 

x-pack/elastic-agent/pkg/agent/application/action_store.go

@@ -36,7 +36,14 @@ func newActionStore(log *logger.Logger, store storeLoad) (*actionStore, error) {
 	var action actionConfigChangeSerializer
 
 	dec := yaml.NewDecoder(reader)
-	if err := dec.Decode(&action); err != nil {
+	err = dec.Decode(&action)
+	if err == io.EOF {
+		return &actionStore{
+			log:   log,
+			store: store,
+		}, nil
+	}
+	if err != nil {
 		return nil, err
 	}
 

x-pack/elastic-agent/pkg/agent/application/enroll_cmd.go

@@ -92,7 +92,7 @@ func NewEnrollCmd(
 	store := storage.NewReplaceOnSuccessStore(
 		configPath,
 		DefaultAgentFleetConfig,
-		storage.NewEncryptedDiskStore(info.AgentConfigFile(), []byte("")),
+		storage.NewDiskStore(info.AgentConfigFile()),
 	)
 
 	return NewEnrollCmdWithStore(

x-pack/elastic-agent/pkg/agent/application/info/agent_id.go

@@ -56,7 +56,7 @@ func generateAgentID() (string, error) {
 
 func loadAgentInfo(forceUpdate bool) (*persistentAgentInfo, error) {
 	agentConfigFile := AgentConfigFile()
-	s := storage.NewEncryptedDiskStore(agentConfigFile, []byte(""))
+	s := storage.NewDiskStore(agentConfigFile)
 
 	agentinfo, err := getInfoFromStore(s)
 	if err != nil {

x-pack/elastic-agent/pkg/agent/application/managed_mode.go

@@ -67,8 +67,7 @@ func newManaged(
 
 	path := info.AgentConfigFile()
 
-	// TODO(ph): Define the encryption password.
-	store := storage.NewEncryptedDiskStore(path, []byte(""))
+	store := storage.NewDiskStore(path)
 	reader, err := store.Load()
 	if err != nil {
 		return nil, errors.New(err, "could not initialize config store",

x-pack/elastic-agent/pkg/agent/storage/storage.go

@@ -14,10 +14,9 @@ import (
 
 	"github.com/elastic/beats/v7/libbeat/common/file"
 	"github.com/elastic/beats/v7/x-pack/elastic-agent/pkg/agent/errors"
-	"github.com/elastic/beats/v7/x-pack/elastic-agent/pkg/crypto"
 )
 
-const perms = 0600
+const perms os.FileMode = 0600
 
 type store interface {
 	Save(io.Reader) error
@@ -76,9 +75,6 @@ func NewReplaceOnSuccessStore(target string, replaceWith []byte, wrapped store)
 
 // Save will replace a target file with new content if the wrapped store is successful.
 func (r *ReplaceOnSuccessStore) Save(in io.Reader) error {
-	// get original permission
-	s, err := os.Stat(r.target)
-
 	// Ensure we can read the target files before delegating any call to the wrapped store.
 	target, err := ioutil.ReadFile(r.target)
 	if err != nil {
@@ -111,7 +107,7 @@ func (r *ReplaceOnSuccessStore) Save(in io.Reader) error {
 			errors.M(errors.MetaKeyPath, r.target))
 	}
 
-	fd, err := os.OpenFile(r.target, os.O_CREATE|os.O_WRONLY, s.Mode())
+	fd, err := os.OpenFile(r.target, os.O_CREATE|os.O_WRONLY, perms)
 	if err != nil {
 		// Rollback on any errors to minimize non working state.
 		if err := file.SafeFileRotate(r.target, backFilename); err != nil {
@@ -187,85 +183,12 @@ func (d *DiskStore) Save(in io.Reader) error {
 
 // Load return a io.ReadCloser for the target file.
 func (d *DiskStore) Load() (io.ReadCloser, error) {
-	return os.OpenFile(d.target, os.O_RDONLY, perms)
-}
-
-// EncryptedDiskStore save the persisted configuration and encrypt the data on disk.
-type EncryptedDiskStore struct {
-	target   string
-	password []byte
-}
-
-// NewEncryptedDiskStore creates an encrypted disk store.
-func NewEncryptedDiskStore(target string, password []byte) *EncryptedDiskStore {
-	return &EncryptedDiskStore{target: target, password: password}
-}
-
-// Save accepts a persistedConfig, encrypt it and saved it to a target file, to do so we will
-// make a temporary files if the write is successful we are replacing the target file with the
-// original content.
-func (d *EncryptedDiskStore) Save(in io.Reader) error {
-	const perms = 0600
-
-	tmpFile := d.target + ".tmp"
-
-	fd, err := os.OpenFile(tmpFile, os.O_CREATE|os.O_TRUNC|os.O_WRONLY, perms)
-	if err != nil {
-		return errors.New(err,
-			fmt.Sprintf("could not save to %s", tmpFile),
-			errors.TypeFilesystem,
-			errors.M(errors.MetaKeyPath, tmpFile))
-	}
-	// Always clean up the temporary file and ignore errors.
-	defer os.Remove(tmpFile)
-
-	w, err := crypto.NewWriterWithDefaults(fd, d.password)
-	if err != nil {
-		return errors.New(err, "could not encrypt the data to disk",
-			errors.TypeFilesystem,
-			errors.M(errors.MetaKeyPath, tmpFile))
-	}
-
-	if _, err := io.Copy(w, in); err != nil {
-		return errors.New(err, "could not save content on disk",
-			errors.TypeFilesystem,
-			errors.M(errors.MetaKeyPath, tmpFile))
-	}
-
-	if err := fd.Close(); err != nil {
-		return errors.New(err, "could not close temporary file",
-			errors.TypeFilesystem,
-			errors.M(errors.MetaKeyPath, tmpFile))
-	}
-
-	if err := file.SafeFileRotate(d.target, tmpFile); err != nil {
-		return errors.New(err,
-			fmt.Sprintf("could not replace target file %s", d.target),
-			errors.TypeFilesystem,
-			errors.M(errors.MetaKeyPath, d.target))
-	}
-
-	return nil
-}
-
-// Load return a io.ReadCloser that will take care on unencrypting the data.
-func (d *EncryptedDiskStore) Load() (io.ReadCloser, error) {
 	fd, err := os.OpenFile(d.target, os.O_RDONLY|os.O_CREATE, perms)
 	if err != nil {
 		return nil, errors.New(err,
 			fmt.Sprintf("could not open %s", d.target),
 			errors.TypeFilesystem,
 			errors.M(errors.MetaKeyPath, d.target))
 	}
-
-	r, err := crypto.NewReaderWithDefaults(fd, d.password)
-	if err != nil {
-		fd.Close()
-		return nil, errors.New(err,
-			fmt.Sprintf("could not decode file %s", d.target),
-			errors.TypeFilesystem,
-			errors.M(errors.MetaKeyPath, d.target))
-	}
-
-	return r, nil
+	return fd, nil
 }

x-pack/elastic-agent/pkg/agent/storage/storage_test.go

@@ -49,6 +49,11 @@ func TestReplaceOrRollbackStore(t *testing.T) {
 
 		require.True(t, bytes.Equal(writtenContent, replaceWith))
 		requireFilesCount(t, dir, 2)
+
+		info, err := os.Stat(target)
+		require.NoError(t, err)
+
+		require.Equal(t, perms, info.Mode())
 	})
 
 	t.Run("when save is not successful", func(t *testing.T) {
@@ -97,6 +102,11 @@ func TestReplaceOrRollbackStore(t *testing.T) {
 
 		require.True(t, bytes.Equal(writtenContent, replaceWith))
 		requireFilesCount(t, dir, 1)
+
+		info, err := os.Stat(target)
+		require.NoError(t, err)
+
+		require.Equal(t, perms, info.Mode())
 	})
 
 	t.Run("when target file do not exist", func(t *testing.T) {
@@ -115,7 +125,7 @@ func TestDiskStore(t *testing.T) {
 		target, err := genFile([]byte("hello world"))
 		require.NoError(t, err)
 		defer os.Remove(target)
-		d := &DiskStore{target: target}
+		d := NewDiskStore(target)
 
 		msg := []byte("bonjour la famille")
 		err = d.Save(bytes.NewReader(msg))
@@ -125,6 +135,11 @@ func TestDiskStore(t *testing.T) {
 		require.NoError(t, err)
 
 		require.Equal(t, msg, content)
+
+		info, err := os.Stat(target)
+		require.NoError(t, err)
+
+		require.Equal(t, perms, info.Mode())
 	})
 
 	t.Run("when the target do no exist", func(t *testing.T) {
@@ -133,7 +148,7 @@ func TestDiskStore(t *testing.T) {
 		defer os.Remove(dir)
 
 		target := filepath.Join(dir, "hello.txt")
-		d := &DiskStore{target: target}
+		d := NewDiskStore(target)
 
 		msg := []byte("bonjour la famille")
 		err = d.Save(bytes.NewReader(msg))
@@ -143,62 +158,31 @@ func TestDiskStore(t *testing.T) {
 		require.NoError(t, err)
 
 		require.Equal(t, msg, content)
+
+		info, err := os.Stat(target)
+		require.NoError(t, err)
+
+		require.Equal(t, perms, info.Mode())
 	})
 
 	t.Run("return an io.ReadCloser to the target file", func(t *testing.T) {
 		msg := []byte("bonjour la famille")
 		target, err := genFile(msg)
 		require.NoError(t, err)
 
-		d := &DiskStore{target: target}
+		d := NewDiskStore(target)
 		r, err := d.Load()
 		require.NoError(t, err)
 		defer r.Close()
 
 		content, err := ioutil.ReadAll(r)
 		require.NoError(t, err)
 		require.Equal(t, msg, content)
-	})
-}
 
-func TestEncryptedDiskStore(t *testing.T) {
-	t.Run("when the target file already exists", func(t *testing.T) {
-		target, err := genFile([]byte("hello world"))
+		info, err := os.Stat(target)
 		require.NoError(t, err)
-		defer os.Remove(target)
-		d := &EncryptedDiskStore{target: target}
 
-		msg := []byte("bonjour la famille")
-		err = d.Save(bytes.NewReader(msg))
-		require.NoError(t, err)
-
-		// lets read the file
-		nd := &EncryptedDiskStore{target: target}
-		r, err := nd.Load()
-		require.NoError(t, err)
-
-		content, err := ioutil.ReadAll(r)
-		require.NoError(t, err)
-
-		require.Equal(t, msg, content)
-	})
-
-	t.Run("when the target do not exist", func(t *testing.T) {
-		dir, err := ioutil.TempDir("", "configs")
-		require.NoError(t, err)
-		defer os.Remove(dir)
-
-		target := filepath.Join(dir, "hello.txt")
-		d := &DiskStore{target: target}
-
-		msg := []byte("bonjour la famille")
-		err = d.Save(bytes.NewReader(msg))
-		require.NoError(t, err)
-
-		content, err := ioutil.ReadFile(target)
-		require.NoError(t, err)
-
-		require.Equal(t, msg, content)
+		require.Equal(t, perms, info.Mode())
 	})
 }
 

x-pack/elastic-agent/pkg/core/monitoring/beats/beats_monitor.go

@@ -115,7 +115,7 @@ func (b *Monitor) EnrichArgs(process, pipelineID string, args []string, isSideca
 			"-E", "logging.files.path="+loggingPath,
 			"-E", "logging.files.name="+logFile,
 			"-E", "logging.files.keepfiles=7",
-			"-E", "logging.files.permission=0644",
+			"-E", "logging.files.permission=0640",
 			"-E", "logging.files.interval=1h",
 		)
 	}