Delay salt initialization for audit backends

audit/audit.go

@@ -25,15 +25,21 @@ type Backend interface {
 	// GetHash is used to return the given data with the backend's hash,
 	// so that a caller can determine if a value in the audit log matches
 	// an expected plaintext value
-	GetHash(string) string
+	GetHash(string) (string, error)
 
 	// Reload is called on SIGHUP for supporting backends.
 	Reload() error
+
+	// Invalidate is called for path invalidation
+	Invalidate()
 }
 
 type BackendConfig struct {
-	// The salt that should be used for any secret obfuscation
+	// The view to store the salt
-	Salt *salt.Salt
+	SaltView logical.Storage
+
+	// The salt config that should be used for any secret obfuscation
+	SaltConfig *salt.Config
 
 	// Config is the opaque user configuration provided when mounting
 	Config map[string]string

audit/format.go

@@ -7,6 +7,8 @@ import (
 	"time"
 
 	"github.com/SermoDigital/jose/jws"
+	"github.com/hashicorp/errwrap"
+	"github.com/hashicorp/vault/helper/salt"
 	"github.com/hashicorp/vault/logical"
 	"github.com/mitchellh/copystructure"
 )
@@ -14,6 +16,7 @@ import (
 type AuditFormatWriter interface {
 	WriteRequest(io.Writer, *AuditRequestEntry) error
 	WriteResponse(io.Writer, *AuditResponseEntry) error
+	Salt() (*salt.Salt, error)
 }
 
 // AuditFormatter implements the Formatter interface, and allows the underlying
@@ -41,6 +44,11 @@ func (f *AuditFormatter) FormatRequest(
 		return fmt.Errorf("no format writer specified")
 	}
 
+	salt, err := f.Salt()
+	if err != nil {
+		return errwrap.Wrapf("error fetching salt: {{err}}", err)
+	}
+
 	if !config.Raw {
 		// Before we copy the structure we must nil out some data
 		// otherwise we will cause reflection to panic and die
@@ -70,7 +78,7 @@ func (f *AuditFormatter) FormatRequest(
 
 		// Hash any sensitive information
 		if auth != nil {
-			if err := Hash(config.Salt, auth); err != nil {
+			if err := Hash(salt, auth); err != nil {
 				return err
 			}
 		}
@@ -80,7 +88,7 @@ func (f *AuditFormatter) FormatRequest(
 		if !config.HMACAccessor && req != nil && req.ClientTokenAccessor != "" {
 			clientTokenAccessor = req.ClientTokenAccessor
 		}
-		if err := Hash(config.Salt, req); err != nil {
+		if err := Hash(salt, req); err != nil {
 			return err
 		}
 		if clientTokenAccessor != "" {
@@ -152,6 +160,11 @@ func (f *AuditFormatter) FormatResponse(
 		return fmt.Errorf("no format writer specified")
 	}
 
+	salt, err := f.Salt()
+	if err != nil {
+		return errwrap.Wrapf("error fetching salt: {{err}}", err)
+	}
+
 	if !config.Raw {
 		// Before we copy the structure we must nil out some data
 		// otherwise we will cause reflection to panic and die
@@ -195,7 +208,7 @@ func (f *AuditFormatter) FormatResponse(
 			if !config.HMACAccessor && auth.Accessor != "" {
 				accessor = auth.Accessor
 			}
-			if err := Hash(config.Salt, auth); err != nil {
+			if err := Hash(salt, auth); err != nil {
 				return err
 			}
 			if accessor != "" {
@@ -208,7 +221,7 @@ func (f *AuditFormatter) FormatResponse(
 		if !config.HMACAccessor && req != nil && req.ClientTokenAccessor != "" {
 			clientTokenAccessor = req.ClientTokenAccessor
 		}
-		if err := Hash(config.Salt, req); err != nil {
+		if err := Hash(salt, req); err != nil {
 			return err
 		}
 		if clientTokenAccessor != "" {
@@ -224,7 +237,7 @@ func (f *AuditFormatter) FormatResponse(
 			if !config.HMACAccessor && resp != nil && resp.WrapInfo != nil && resp.WrapInfo.WrappedAccessor != "" {
 				wrappedAccessor = resp.WrapInfo.WrappedAccessor
 			}
-			if err := Hash(config.Salt, resp); err != nil {
+			if err := Hash(salt, resp); err != nil {
 				return err
 			}
 			if accessor != "" {

audit/format_json.go

@@ -4,12 +4,15 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
+
+	"github.com/hashicorp/vault/helper/salt"
 )
 
 // JSONFormatWriter is an AuditFormatWriter implementation that structures data into
 // a JSON format.
 type JSONFormatWriter struct {
 	Prefix   string
+	SaltFunc func() (*salt.Salt, error)
 }
 
 func (f *JSONFormatWriter) WriteRequest(w io.Writer, req *AuditRequestEntry) error {
@@ -43,3 +46,7 @@ func (f *JSONFormatWriter) WriteResponse(w io.Writer, resp *AuditResponseEntry)
 	enc := json.NewEncoder(w)
 	return enc.Encode(resp)
 }
+
+func (f *JSONFormatWriter) Salt() (*salt.Salt, error) {
+	return f.SaltFunc()
+}

audit/format_json_test.go

@@ -15,6 +15,13 @@ import (
 )
 
 func TestFormatJSON_formatRequest(t *testing.T) {
+	salter, err := salt.NewSalt(nil, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	saltFunc := func() (*salt.Salt, error) {
+		return salter, nil
+	}
 	cases := map[string]struct {
 		Auth   *logical.Auth
 		Req    *logical.Request
@@ -67,12 +74,10 @@ func TestFormatJSON_formatRequest(t *testing.T) {
 		formatter := AuditFormatter{
 			AuditFormatWriter: &JSONFormatWriter{
 				Prefix:   tc.Prefix,
+				SaltFunc: saltFunc,
 			},
 		}
-		salter, _ := salt.NewSalt(nil, nil)
+		config := FormatterConfig{}
-		config := FormatterConfig{
-			Salt: salter,
-		}
 		if err := formatter.FormatRequest(&buf, config, tc.Auth, tc.Req, tc.Err); err != nil {
 			t.Fatalf("bad: %s\nerr: %s", name, err)
 		}

audit/format_jsonx.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"io"
 
+	"github.com/hashicorp/vault/helper/salt"
 	"github.com/jefferai/jsonx"
 )
 
@@ -12,6 +13,7 @@ import (
 // a XML format.
 type JSONxFormatWriter struct {
 	Prefix   string
+	SaltFunc func() (*salt.Salt, error)
 }
 
 func (f *JSONxFormatWriter) WriteRequest(w io.Writer, req *AuditRequestEntry) error {
@@ -65,3 +67,7 @@ func (f *JSONxFormatWriter) WriteResponse(w io.Writer, resp *AuditResponseEntry)
 	_, err = w.Write(xmlBytes)
 	return err
 }
+
+func (f *JSONxFormatWriter) Salt() (*salt.Salt, error) {
+	return f.SaltFunc()
+}

audit/format_jsonx_test.go

@@ -13,6 +13,13 @@ import (
 )
 
 func TestFormatJSONx_formatRequest(t *testing.T) {
+	salter, err := salt.NewSalt(nil, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	saltFunc := func() (*salt.Salt, error) {
+		return salter, nil
+	}
 	cases := map[string]struct {
 		Auth     *logical.Auth
 		Req      *logical.Request
@@ -68,11 +75,10 @@ func TestFormatJSONx_formatRequest(t *testing.T) {
 		formatter := AuditFormatter{
 			AuditFormatWriter: &JSONxFormatWriter{
 				Prefix:   tc.Prefix,
+				SaltFunc: saltFunc,
 			},
 		}
-		salter, _ := salt.NewSalt(nil, nil)
 		config := FormatterConfig{
-			Salt:     salter,
 			OmitTime: true,
 		}
 		if err := formatter.FormatRequest(&buf, config, tc.Auth, tc.Req, tc.Err); err != nil {

audit/format_test.go

@@ -10,6 +10,8 @@ import (
 )
 
 type noopFormatWriter struct {
+	salt     *salt.Salt
+	SaltFunc func() (*salt.Salt, error)
 }
 
 func (n *noopFormatWriter) WriteRequest(_ io.Writer, _ *AuditRequestEntry) error {
@@ -20,11 +22,20 @@ func (n *noopFormatWriter) WriteResponse(_ io.Writer, _ *AuditResponseEntry) err
 	return nil
 }
 
-func TestFormatRequestErrors(t *testing.T) {
+func (n *noopFormatWriter) Salt() (*salt.Salt, error) {
-	salter, _ := salt.NewSalt(nil, nil)
+	if n.salt != nil {
-	config := FormatterConfig{
+		return n.salt, nil
-		Salt: salter,
 	}
+	var err error
+	n.salt, err = salt.NewSalt(nil, nil)
+	if err != nil {
+		return nil, err
+	}
+	return n.salt, nil
+}
+
+func TestFormatRequestErrors(t *testing.T) {
+	config := FormatterConfig{}
 	formatter := AuditFormatter{
 		AuditFormatWriter: &noopFormatWriter{},
 	}
@@ -38,10 +49,7 @@ func TestFormatRequestErrors(t *testing.T) {
 }
 
 func TestFormatResponseErrors(t *testing.T) {
-	salter, _ := salt.NewSalt(nil, nil)
+	config := FormatterConfig{}
-	config := FormatterConfig{
-		Salt: salter,
-	}
 	formatter := AuditFormatter{
 		AuditFormatWriter: &noopFormatWriter{},
 	}

audit/formatter.go

@@ -3,7 +3,6 @@ package audit
 import (
 	"io"
 
-	"github.com/hashicorp/vault/helper/salt"
 	"github.com/hashicorp/vault/logical"
 )
 
@@ -19,7 +18,6 @@ type Formatter interface {
 
 type FormatterConfig struct {
 	Raw          bool
-	Salt         *salt.Salt
 	HMACAccessor bool
 
 	// This should only ever be used in a testing context

builtin/audit/file/backend.go

@@ -8,12 +8,16 @@ import (
 	"sync"
 
 	"github.com/hashicorp/vault/audit"
+	"github.com/hashicorp/vault/helper/salt"
 	"github.com/hashicorp/vault/logical"
 )
 
 func Factory(conf *audit.BackendConfig) (audit.Backend, error) {
-	if conf.Salt == nil {
+	if conf.SaltConfig == nil {
-		return nil, fmt.Errorf("nil salt")
+		return nil, fmt.Errorf("nil salt config")
+	}
+	if conf.SaltView == nil {
+		return nil, fmt.Errorf("nil salt view")
 	}
 
 	path, ok := conf.Config["file_path"]
@@ -67,9 +71,10 @@ func Factory(conf *audit.BackendConfig) (audit.Backend, error) {
 	b := &Backend{
 		path:       path,
 		mode:       mode,
+		saltConfig: conf.SaltConfig,
+		saltView:   conf.SaltView,
 		formatConfig: audit.FormatterConfig{
 			Raw:          logRaw,
-			Salt:         conf.Salt,
 			HMACAccessor: hmacAccessor,
 		},
 	}
@@ -78,10 +83,12 @@ func Factory(conf *audit.BackendConfig) (audit.Backend, error) {
 	case "json":
 		b.formatter.AuditFormatWriter = &audit.JSONFormatWriter{
 			Prefix:   conf.Config["prefix"],
+			SaltFunc: b.Salt,
 		}
 	case "jsonx":
 		b.formatter.AuditFormatWriter = &audit.JSONxFormatWriter{
 			Prefix:   conf.Config["prefix"],
+			SaltFunc: b.Salt,
 		}
 	}
 
@@ -109,10 +116,39 @@ type Backend struct {
 	fileLock sync.RWMutex
 	f        *os.File
 	mode     os.FileMode
+
+	saltMutex  sync.RWMutex
+	salt       *salt.Salt
+	saltConfig *salt.Config
+	saltView   logical.Storage
 }
 
-func (b *Backend) GetHash(data string) string {
+func (b *Backend) Salt() (*salt.Salt, error) {
-	return audit.HashString(b.formatConfig.Salt, data)
+	b.saltMutex.RLock()
+	if b.salt != nil {
+		defer b.saltMutex.RUnlock()
+		return b.salt, nil
+	}
+	b.saltMutex.RUnlock()
+	b.saltMutex.Lock()
+	defer b.saltMutex.Unlock()
+	if b.salt != nil {
+		return b.salt, nil
+	}
+	salt, err := salt.NewSalt(b.saltView, b.saltConfig)
+	if err != nil {
+		return nil, err
+	}
+	b.salt = salt
+	return salt, nil
+}
+
+func (b *Backend) GetHash(data string) (string, error) {
+	salt, err := b.Salt()
+	if err != nil {
+		return "", err
+	}
+	return audit.HashString(salt, data), nil
 }
 
 func (b *Backend) LogRequest(auth *logical.Auth, req *logical.Request, outerErr error) error {
@@ -189,3 +225,9 @@ func (b *Backend) Reload() error {
 
 	return b.open()
 }
+
+func (b *Backend) Invalidate() {
+	b.saltMutex.Lock()
+	defer b.saltMutex.Unlock()
+	b.salt = nil
+}

builtin/audit/file/backend_test.go

@@ -9,11 +9,10 @@ import (
 
 	"github.com/hashicorp/vault/audit"
 	"github.com/hashicorp/vault/helper/salt"
+	"github.com/hashicorp/vault/logical"
 )
 
 func TestAuditFile_fileModeNew(t *testing.T) {
-	salter, _ := salt.NewSalt(nil, nil)
-
 	modeStr := "0777"
 	mode, err := strconv.ParseUint(modeStr, 8, 32)
 
@@ -28,7 +27,8 @@ func TestAuditFile_fileModeNew(t *testing.T) {
 	}
 
 	_, err = Factory(&audit.BackendConfig{
-		Salt:   salter,
+		SaltConfig: &salt.Config{},
+		SaltView:   &logical.InmemStorage{},
 		Config:     config,
 	})
 	if err != nil {
@@ -45,8 +45,6 @@ func TestAuditFile_fileModeNew(t *testing.T) {
 }
 
 func TestAuditFile_fileModeExisting(t *testing.T) {
-	salter, _ := salt.NewSalt(nil, nil)
-
 	f, err := ioutil.TempFile("", "test")
 	if err != nil {
 		t.Fatalf("Failure to create test file.")
@@ -68,8 +66,9 @@ func TestAuditFile_fileModeExisting(t *testing.T) {
 	}
 
 	_, err = Factory(&audit.BackendConfig{
-		Salt:   salter,
 		Config:     config,
+		SaltConfig: &salt.Config{},
+		SaltView:   &logical.InmemStorage{},
 	})
 	if err != nil {
 		t.Fatal(err)

builtin/audit/socket/backend.go

@@ -11,12 +11,16 @@ import (
 	multierror "github.com/hashicorp/go-multierror"
 	"github.com/hashicorp/vault/audit"
 	"github.com/hashicorp/vault/helper/parseutil"
+	"github.com/hashicorp/vault/helper/salt"
 	"github.com/hashicorp/vault/logical"
 )
 
 func Factory(conf *audit.BackendConfig) (audit.Backend, error) {
-	if conf.Salt == nil {
+	if conf.SaltConfig == nil {
-		return nil, fmt.Errorf("nil salt passed in")
+		return nil, fmt.Errorf("nil salt config")
+	}
+	if conf.SaltView == nil {
+		return nil, fmt.Errorf("nil salt view")
 	}
 
 	address, ok := conf.Config["address"]
@@ -75,11 +79,13 @@ func Factory(conf *audit.BackendConfig) (audit.Backend, error) {
 
 	b := &Backend{
 		connection: conn,
+		saltConfig: conf.SaltConfig,
+		saltView:   conf.SaltView,
 		formatConfig: audit.FormatterConfig{
 			Raw:          logRaw,
-			Salt:         conf.Salt,
 			HMACAccessor: hmacAccessor,
 		},
+
 		writeDuration: writeDuration,
 		address:       address,
 		socketType:    socketType,
@@ -89,10 +95,12 @@ func Factory(conf *audit.BackendConfig) (audit.Backend, error) {
 	case "json":
 		b.formatter.AuditFormatWriter = &audit.JSONFormatWriter{
 			Prefix:   conf.Config["prefix"],
+			SaltFunc: b.Salt,
 		}
 	case "jsonx":
 		b.formatter.AuditFormatWriter = &audit.JSONxFormatWriter{
 			Prefix:   conf.Config["prefix"],
+			SaltFunc: b.Salt,
 		}
 	}
 
@@ -111,10 +119,19 @@ type Backend struct {
 	socketType    string
 
 	sync.Mutex
+
+	saltMutex  sync.RWMutex
+	salt       *salt.Salt
+	saltConfig *salt.Config
+	saltView   logical.Storage
 }
 
-func (b *Backend) GetHash(data string) string {
+func (b *Backend) GetHash(data string) (string, error) {
-	return audit.HashString(b.formatConfig.Salt, data)
+	salt, err := b.Salt()
+	if err != nil {
+		return "", err
+	}
+	return audit.HashString(salt, data), nil
 }
 
 func (b *Backend) LogRequest(auth *logical.Auth, req *logical.Request, outerErr error) error {
@@ -198,3 +215,29 @@ func (b *Backend) Reload() error {
 
 	return err
 }
+
+func (b *Backend) Salt() (*salt.Salt, error) {
+	b.saltMutex.RLock()
+	if b.salt != nil {
+		defer b.saltMutex.RUnlock()
+		return b.salt, nil
+	}
+	b.saltMutex.RUnlock()
+	b.saltMutex.Lock()
+	defer b.saltMutex.Unlock()
+	if b.salt != nil {
+		return b.salt, nil
+	}
+	salt, err := salt.NewSalt(b.saltView, b.saltConfig)
+	if err != nil {
+		return nil, err
+	}
+	b.salt = salt
+	return salt, nil
+}
+
+func (b *Backend) Invalidate() {
+	b.saltMutex.Lock()
+	defer b.saltMutex.Unlock()
+	b.salt = nil
+}

builtin/audit/syslog/backend.go

@@ -4,15 +4,20 @@ import (
 	"bytes"
 	"fmt"
 	"strconv"
+	"sync"
 
 	"github.com/hashicorp/go-syslog"
 	"github.com/hashicorp/vault/audit"
+	"github.com/hashicorp/vault/helper/salt"
 	"github.com/hashicorp/vault/logical"
 )
 
 func Factory(conf *audit.BackendConfig) (audit.Backend, error) {
-	if conf.Salt == nil {
+	if conf.SaltConfig == nil {
-		return nil, fmt.Errorf("Nil salt passed in")
+		return nil, fmt.Errorf("nil salt config")
+	}
+	if conf.SaltView == nil {
+		return nil, fmt.Errorf("nil salt view")
 	}
 
 	// Get facility or default to AUTH
@@ -65,9 +70,10 @@ func Factory(conf *audit.BackendConfig) (audit.Backend, error) {
 
 	b := &Backend{
 		logger:     logger,
+		saltConfig: conf.SaltConfig,
+		saltView:   conf.SaltView,
 		formatConfig: audit.FormatterConfig{
 			Raw:          logRaw,
-			Salt:         conf.Salt,
 			HMACAccessor: hmacAccessor,
 		},
 	}
@@ -76,10 +82,12 @@ func Factory(conf *audit.BackendConfig) (audit.Backend, error) {
 	case "json":
 		b.formatter.AuditFormatWriter = &audit.JSONFormatWriter{
 			Prefix:   conf.Config["prefix"],
+			SaltFunc: b.Salt,
 		}
 	case "jsonx":
 		b.formatter.AuditFormatWriter = &audit.JSONxFormatWriter{
 			Prefix:   conf.Config["prefix"],
+			SaltFunc: b.Salt,
 		}
 	}
 
@@ -92,10 +100,19 @@ type Backend struct {
 
 	formatter    audit.AuditFormatter
 	formatConfig audit.FormatterConfig
+
+	saltMutex  sync.RWMutex
+	salt       *salt.Salt
+	saltConfig *salt.Config
+	saltView   logical.Storage
 }
 
-func (b *Backend) GetHash(data string) string {
+func (b *Backend) GetHash(data string) (string, error) {
-	return audit.HashString(b.formatConfig.Salt, data)
+	salt, err := b.Salt()
+	if err != nil {
+		return "", err
+	}
+	return audit.HashString(salt, data), nil
 }
 
 func (b *Backend) LogRequest(auth *logical.Auth, req *logical.Request, outerErr error) error {
@@ -123,3 +140,29 @@ func (b *Backend) LogResponse(auth *logical.Auth, req *logical.Request, resp *lo
 func (b *Backend) Reload() error {
 	return nil
 }
+
+func (b *Backend) Salt() (*salt.Salt, error) {
+	b.saltMutex.RLock()
+	if b.salt != nil {
+		defer b.saltMutex.RUnlock()
+		return b.salt, nil
+	}
+	b.saltMutex.RUnlock()
+	b.saltMutex.Lock()
+	defer b.saltMutex.Unlock()
+	if b.salt != nil {
+		return b.salt, nil
+	}
+	salt, err := salt.NewSalt(b.saltView, b.saltConfig)
+	if err != nil {
+		return nil, err
+	}
+	b.salt = salt
+	return salt, nil
+}
+
+func (b *Backend) Invalidate() {
+	b.saltMutex.Lock()
+	defer b.saltMutex.Unlock()
+	b.salt = nil
+}

vault/audit.go

@@ -368,16 +368,15 @@ func (c *Core) newAuditBackend(entry *MountEntry, view logical.Storage, conf map
 	if !ok {
 		return nil, fmt.Errorf("unknown backend type: %s", entry.Type)
 	}
-	salter, err := salt.NewSalt(view, &salt.Config{
+	saltConfig := &salt.Config{
 		HMAC:     sha256.New,
 		HMACType: "hmac-sha256",
-	})
+		Location: salt.DefaultLocation,
-	if err != nil {
-		return nil, fmt.Errorf("core: unable to generate salt: %v", err)
 	}
 
 	be, err := f(&audit.BackendConfig{
-		Salt:   salter,
+		SaltView:   view,
+		SaltConfig: saltConfig,
 		Config:     conf,
 	})
 	if err != nil {
@@ -474,20 +473,25 @@ func (a *AuditBroker) GetHash(name string, input string) (string, error) {
 		return "", fmt.Errorf("unknown audit backend %s", name)
 	}
 
-	return be.backend.GetHash(input), nil
+	return be.backend.GetHash(input)
 }
 
 // LogRequest is used to ensure all the audit backends have an opportunity to
 // log the given request and that *at least one* succeeds.
-func (a *AuditBroker) LogRequest(auth *logical.Auth, req *logical.Request, headersConfig *AuditedHeadersConfig, outerErr error) (retErr error) {
+func (a *AuditBroker) LogRequest(auth *logical.Auth, req *logical.Request, headersConfig *AuditedHeadersConfig, outerErr error) (ret error) {
 	defer metrics.MeasureSince([]string{"audit", "log_request"}, time.Now())
 	a.RLock()
 	defer a.RUnlock()
+
+	var retErr *multierror.Error
+
 	defer func() {
 		if r := recover(); r != nil {
 			a.logger.Error("audit: panic during logging", "request_path", req.Path, "error", r)
 			retErr = multierror.Append(retErr, fmt.Errorf("panic generating audit log"))
 		}
+
+		ret = retErr.ErrorOrNil()
 	}()
 
 	// All logged requests must have an identifier
@@ -506,36 +510,46 @@ func (a *AuditBroker) LogRequest(auth *logical.Auth, req *logical.Request, heade
 	anyLogged := false
 	for name, be := range a.backends {
 		req.Headers = nil
-		req.Headers = headersConfig.ApplyConfig(headers, be.backend.GetHash)
+		transHeaders, thErr := headersConfig.ApplyConfig(headers, be.backend.GetHash)
+		if thErr != nil {
+			a.logger.Error("audit: backend failed to include headers", "backend", name, "error", thErr)
+			continue
+		}
+		req.Headers = transHeaders
 
 		start := time.Now()
-		err := be.backend.LogRequest(auth, req, outerErr)
+		lrErr := be.backend.LogRequest(auth, req, outerErr)
 		metrics.MeasureSince([]string{"audit", name, "log_request"}, start)
-		if err != nil {
+		if lrErr != nil {
-			a.logger.Error("audit: backend failed to log request", "backend", name, "error", err)
+			a.logger.Error("audit: backend failed to log request", "backend", name, "error", lrErr)
 		} else {
 			anyLogged = true
 		}
 	}
 	if !anyLogged && len(a.backends) > 0 {
 		retErr = multierror.Append(retErr, fmt.Errorf("no audit backend succeeded in logging the request"))
-		return
 	}
-	return nil
+
+	return retErr.ErrorOrNil()
 }
 
 // LogResponse is used to ensure all the audit backends have an opportunity to
 // log the given response and that *at least one* succeeds.
 func (a *AuditBroker) LogResponse(auth *logical.Auth, req *logical.Request,
-	resp *logical.Response, headersConfig *AuditedHeadersConfig, err error) (reterr error) {
+	resp *logical.Response, headersConfig *AuditedHeadersConfig, err error) (ret error) {
 	defer metrics.MeasureSince([]string{"audit", "log_response"}, time.Now())
 	a.RLock()
 	defer a.RUnlock()
+
+	var retErr *multierror.Error
+
 	defer func() {
 		if r := recover(); r != nil {
 			a.logger.Error("audit: panic during logging", "request_path", req.Path, "error", r)
-			reterr = fmt.Errorf("panic generating audit log")
+			retErr = multierror.Append(retErr, fmt.Errorf("panic generating audit log"))
 		}
+
+		ret = retErr.ErrorOrNil()
 	}()
 
 	headers := req.Headers
@@ -547,19 +561,35 @@ func (a *AuditBroker) LogResponse(auth *logical.Auth, req *logical.Request,
 	anyLogged := false
 	for name, be := range a.backends {
 		req.Headers = nil
-		req.Headers = headersConfig.ApplyConfig(headers, be.backend.GetHash)
+		transHeaders, thErr := headersConfig.ApplyConfig(headers, be.backend.GetHash)
+		if thErr != nil {
+			a.logger.Error("audit: backend failed to include headers", "backend", name, "error", thErr)
+			continue
+		}
+		req.Headers = transHeaders
 
 		start := time.Now()
-		err := be.backend.LogResponse(auth, req, resp, err)
+		lrErr := be.backend.LogResponse(auth, req, resp, err)
 		metrics.MeasureSince([]string{"audit", name, "log_response"}, start)
-		if err != nil {
+		if lrErr != nil {
-			a.logger.Error("audit: backend failed to log response", "backend", name, "error", err)
+			a.logger.Error("audit: backend failed to log response", "backend", name, "error", lrErr)
 		} else {
 			anyLogged = true
 		}
 	}
 	if !anyLogged && len(a.backends) > 0 {
-		return fmt.Errorf("no audit backend succeeded in logging the response")
+		retErr = multierror.Append(retErr, fmt.Errorf("no audit backend succeeded in logging the response"))
+	}
+
+	return retErr.ErrorOrNil()
+}
+
+func (a *AuditBroker) Invalidate(key string) {
+	// For now we ignore the key as this would only apply to salts. We just
+	// sort of brute force it on each one.
+	a.Lock()
+	defer a.Unlock()
+	for _, be := range a.backends {
+		be.backend.Invalidate()
 	}
-	return nil
 }

vault/audit_test.go

@@ -3,6 +3,8 @@ package vault
 import (
 	"fmt"
 	"reflect"
+	"strings"
+	"sync"
 	"testing"
 	"time"
 
@@ -13,6 +15,7 @@ import (
 	"github.com/hashicorp/vault/audit"
 	"github.com/hashicorp/vault/helper/jsonutil"
 	"github.com/hashicorp/vault/helper/logformat"
+	"github.com/hashicorp/vault/helper/salt"
 	"github.com/hashicorp/vault/logical"
 	log "github.com/mgutz/logxi/v1"
 	"github.com/mitchellh/copystructure"
@@ -31,6 +34,9 @@ type NoopAudit struct {
 	RespReq  []*logical.Request
 	Resp     []*logical.Response
 	RespErrs []error
+
+	salt      *salt.Salt
+	saltMutex sync.RWMutex
 }
 
 func (n *NoopAudit) LogRequest(a *logical.Auth, r *logical.Request, err error) error {
@@ -49,14 +55,44 @@ func (n *NoopAudit) LogResponse(a *logical.Auth, r *logical.Request, re *logical
 	return n.RespErr
 }
 
-func (n *NoopAudit) GetHash(data string) string {
+func (n *NoopAudit) Salt() (*salt.Salt, error) {
-	return n.Config.Salt.GetIdentifiedHMAC(data)
+	n.saltMutex.RLock()
+	if n.salt != nil {
+		defer n.saltMutex.RUnlock()
+		return n.salt, nil
+	}
+	n.saltMutex.RUnlock()
+	n.saltMutex.Lock()
+	defer n.saltMutex.Unlock()
+	if n.salt != nil {
+		return n.salt, nil
+	}
+	salt, err := salt.NewSalt(n.Config.SaltView, n.Config.SaltConfig)
+	if err != nil {
+		return nil, err
+	}
+	n.salt = salt
+	return salt, nil
+}
+
+func (n *NoopAudit) GetHash(data string) (string, error) {
+	salt, err := n.Salt()
+	if err != nil {
+		return "", err
+	}
+	return salt.GetIdentifiedHMAC(data), nil
 }
 
 func (n *NoopAudit) Reload() error {
 	return nil
 }
 
+func (n *NoopAudit) Invalidate() {
+	n.saltMutex.Lock()
+	defer n.saltMutex.Unlock()
+	n.salt = nil
+}
+
 func TestCore_EnableAudit(t *testing.T) {
 	c, keys, _ := TestCoreUnsealed(t)
 	c.auditBackends["noop"] = func(config *audit.BackendConfig) (audit.Backend, error) {
@@ -508,7 +544,7 @@ func TestAuditBroker_LogResponse(t *testing.T) {
 			t.Fatalf("Bad: %#v", a.Resp[0])
 		}
 		if !reflect.DeepEqual(a.RespErrs[0], respErr) {
-			t.Fatalf("Bad: %#v", a.RespErrs[0])
+			t.Fatalf("Expected\n%v\nGot\n%#v", respErr, a.RespErrs[0])
 		}
 	}
 
@@ -522,7 +558,7 @@ func TestAuditBroker_LogResponse(t *testing.T) {
 	// Should FAIL work with both failing backends
 	a2.RespErr = fmt.Errorf("failed")
 	err = b.LogResponse(auth, req, resp, headersConf, respErr)
-	if err.Error() != "no audit backend succeeded in logging the response" {
+	if !strings.Contains(err.Error(), "no audit backend succeeded in logging the response") {
 		t.Fatalf("err: %v", err)
 	}
 }

vault/audited_headers.go

@@ -88,7 +88,7 @@ func (a *AuditedHeadersConfig) remove(header string) error {
 
 // ApplyConfig returns a map of approved headers and their values, either
 // hmac'ed or plaintext
-func (a *AuditedHeadersConfig) ApplyConfig(headers map[string][]string, hashFunc func(string) string) (result map[string][]string) {
+func (a *AuditedHeadersConfig) ApplyConfig(headers map[string][]string, hashFunc func(string) (string, error)) (result map[string][]string, retErr error) {
 	// Grab a read lock
 	a.RLock()
 	defer a.RUnlock()
@@ -110,7 +110,11 @@ func (a *AuditedHeadersConfig) ApplyConfig(headers map[string][]string, hashFunc
 			// Optionally hmac the values
 			if settings.HMAC {
 				for i, el := range hVals {
-					hVals[i] = hashFunc(el)
+					hVal, err := hashFunc(el)
+					if err != nil {
+						return nil, err
+					}
+					hVals[i] = hVal
 				}
 			}
 
@@ -118,7 +122,7 @@ func (a *AuditedHeadersConfig) ApplyConfig(headers map[string][]string, hashFunc
 		}
 	}
 
-	return
+	return result, nil
 }
 
 // Initalize the headers config by loading from the barrier view

vault/audited_headers_test.go

@@ -166,9 +166,12 @@ func TestAuditedHeadersConfig_ApplyConfig(t *testing.T) {
 		"Content-Type":   []string{"json"},
 	}
 
-	hashFunc := func(s string) string { return "hashed" }
+	hashFunc := func(s string) (string, error) { return "hashed", nil }
 
-	result := conf.ApplyConfig(reqHeaders, hashFunc)
+	result, err := conf.ApplyConfig(reqHeaders, hashFunc)
+	if err != nil {
+		t.Fatal(err)
+	}
 
 	expected := map[string][]string{
 		"x-test-header":  []string{"foo"},
@@ -214,7 +217,7 @@ func BenchmarkAuditedHeaderConfig_ApplyConfig(b *testing.B) {
 		b.Fatal(err)
 	}
 
-	hashFunc := func(s string) string { return salter.GetIdentifiedHMAC(s) }
+	hashFunc := func(s string) (string, error) { return salter.GetIdentifiedHMAC(s), nil }
 
 	// Reset the timer since we did a lot above
 	b.ResetTimer()

vault/logical_system_test.go

@@ -1254,13 +1254,11 @@ func TestSystemBackend_auditHash(t *testing.T) {
 			Key:   "salt",
 			Value: []byte("foo"),
 		})
-		var err error
+		config.SaltView = view
-		config.Salt, err = salt.NewSalt(view, &salt.Config{
+		config.SaltConfig = &salt.Config{
 			HMAC:     sha256.New,
 			HMACType: "hmac-sha256",
-		})
+			Location: salt.DefaultLocation,
-		if err != nil {
-			t.Fatalf("error getting new salt: %v", err)
 		}
 		return &NoopAudit{
 			Config: config,

vault/testing.go

@@ -14,6 +14,7 @@ import (
 	"os"
 	"os/exec"
 	"path/filepath"
+	"sync"
 	"testing"
 	"time"
 
@@ -111,14 +112,11 @@ func testCoreConfig(t testing.TB, physicalBackend physical.Backend, logger log.L
 				Key:   "salt",
 				Value: []byte("foo"),
 			})
-			var err error
+			config.SaltConfig = &salt.Config{
-			config.Salt, err = salt.NewSalt(view, &salt.Config{
 				HMAC:     sha256.New,
 				HMACType: "hmac-sha256",
-			})
-			if err != nil {
-				t.Fatalf("error getting new salt: %v", err)
 			}
+			config.SaltView = view
 			return &noopAudit{
 				Config: config,
 			}, nil
@@ -443,10 +441,16 @@ func AddTestLogicalBackend(name string, factory logical.Factory) error {
 
 type noopAudit struct {
 	Config    *audit.BackendConfig
+	salt      *salt.Salt
+	saltMutex sync.RWMutex
 }
 
-func (n *noopAudit) GetHash(data string) string {
+func (n *noopAudit) GetHash(data string) (string, error) {
-	return n.Config.Salt.GetIdentifiedHMAC(data)
+	salt, err := n.Salt()
+	if err != nil {
+		return "", err
+	}
+	return salt.GetIdentifiedHMAC(data), nil
 }
 
 func (n *noopAudit) LogRequest(a *logical.Auth, r *logical.Request, e error) error {
@@ -461,6 +465,32 @@ func (n *noopAudit) Reload() error {
 	return nil
 }
 
+func (n *noopAudit) Invalidate() {
+	n.saltMutex.Lock()
+	defer n.saltMutex.Unlock()
+	n.salt = nil
+}
+
+func (n *noopAudit) Salt() (*salt.Salt, error) {
+	n.saltMutex.RLock()
+	if n.salt != nil {
+		defer n.saltMutex.RUnlock()
+		return n.salt, nil
+	}
+	n.saltMutex.RUnlock()
+	n.saltMutex.Lock()
+	defer n.saltMutex.Unlock()
+	if n.salt != nil {
+		return n.salt, nil
+	}
+	salt, err := salt.NewSalt(n.Config.SaltView, n.Config.SaltConfig)
+	if err != nil {
+		return nil, err
+	}
+	n.salt = salt
+	return salt, nil
+}
+
 type rawHTTP struct{}
 
 func (n *rawHTTP) HandleRequest(req *logical.Request) (*logical.Response, error) {