open-vault/audit/format_test.go
Max Bowsher d1f2b101b5
Add option 'elide_list_responses' to audit backends (#18128)
This PR relates to a feature request logged through HashiCorp commercial
support.

Vault lacks pagination in its APIs. As a result, certain list operations
can return **very** large responses.  The user's chosen audit sinks may
experience difficulty consuming audit records that swell to tens of
megabytes of JSON.

In our case, one of the systems consuming audit log data could not cope,
and failed.

The responses of list operations are typically not very interesting, as
they are mostly lists of keys, or, even when they include a "key_info"
field, are not returning confidential information. They become even less
interesting once HMAC-ed by the audit system.

Some example Vault "list" operations that are prone to becoming very
large in an active Vault installation are:

    auth/token/accessors/
    identity/entity/id/
    identity/entity-alias/id/
    pki/certs/

In response, I've coded a new option that can be applied to audit
backends, `elide_list_responses`. When enabled, response data is elided
from audit logs, only when the operation type is "list".

For added safety, the elision only applies to the "keys" and "key_info"
fields within the response data - these are conventionally the only
fields present in a list response - see logical.ListResponse, and
logical.ListResponseWithInfo. However, other fields are technically
possible if a plugin author writes unusual code, and these will be
preserved in the audit log even with this option enabled.

The elision replaces the values of the "keys" and "key_info" fields with
an integer count of the number of entries. This allows even the elided
audit logs to still be useful for answering questions like "Was any data
returned?" or "How many records were listed?".
2023-01-11 16:15:52 -05:00

222 lines
5.9 KiB
Go

package audit
import (
"context"
"io"
"testing"
"github.com/hashicorp/vault/helper/namespace"
"github.com/hashicorp/vault/sdk/helper/salt"
"github.com/hashicorp/vault/sdk/logical"
"github.com/mitchellh/copystructure"
"github.com/stretchr/testify/assert"
"github.com/stretchr/testify/require"
)
type testingFormatWriter struct {
salt *salt.Salt
lastRequest *AuditRequestEntry
lastResponse *AuditResponseEntry
}
func (fw *testingFormatWriter) WriteRequest(_ io.Writer, entry *AuditRequestEntry) error {
fw.lastRequest = entry
return nil
}
func (fw *testingFormatWriter) WriteResponse(_ io.Writer, entry *AuditResponseEntry) error {
fw.lastResponse = entry
return nil
}
func (fw *testingFormatWriter) Salt(ctx context.Context) (*salt.Salt, error) {
if fw.salt != nil {
return fw.salt, nil
}
var err error
fw.salt, err = salt.NewSalt(ctx, nil, nil)
if err != nil {
return nil, err
}
return fw.salt, nil
}
// hashExpectedValueForComparison replicates enough of the audit HMAC process on a piece of expected data in a test,
// so that we can use assert.Equal to compare the expected and output values.
func (fw *testingFormatWriter) hashExpectedValueForComparison(input map[string]interface{}) map[string]interface{} {
// Copy input before modifying, since we may re-use the same data in another test
copied, err := copystructure.Copy(input)
if err != nil {
panic(err)
}
copiedAsMap := copied.(map[string]interface{})
salter, err := fw.Salt(context.Background())
if err != nil {
panic(err)
}
err = hashMap(salter.GetIdentifiedHMAC, copiedAsMap, nil)
if err != nil {
panic(err)
}
return copiedAsMap
}
func TestFormatRequestErrors(t *testing.T) {
config := FormatterConfig{}
formatter := AuditFormatter{
AuditFormatWriter: &testingFormatWriter{},
}
if err := formatter.FormatRequest(context.Background(), io.Discard, config, &logical.LogInput{}); err == nil {
t.Fatal("expected error due to nil request")
}
in := &logical.LogInput{
Request: &logical.Request{},
}
if err := formatter.FormatRequest(context.Background(), nil, config, in); err == nil {
t.Fatal("expected error due to nil writer")
}
}
func TestFormatResponseErrors(t *testing.T) {
config := FormatterConfig{}
formatter := AuditFormatter{
AuditFormatWriter: &testingFormatWriter{},
}
if err := formatter.FormatResponse(context.Background(), io.Discard, config, &logical.LogInput{}); err == nil {
t.Fatal("expected error due to nil request")
}
in := &logical.LogInput{
Request: &logical.Request{},
}
if err := formatter.FormatResponse(context.Background(), nil, config, in); err == nil {
t.Fatal("expected error due to nil writer")
}
}
func TestElideListResponses(t *testing.T) {
tfw := testingFormatWriter{}
formatter := AuditFormatter{&tfw}
ctx := namespace.RootContext(context.Background())
type test struct {
name string
inputData map[string]interface{}
expectedData map[string]interface{}
}
tests := []test{
{
"nil data",
nil,
nil,
},
{
"Normal list (keys only)",
map[string]interface{}{
"keys": []string{"foo", "bar", "baz"},
},
map[string]interface{}{
"keys": 3,
},
},
{
"Enhanced list (has key_info)",
map[string]interface{}{
"keys": []string{"foo", "bar", "baz", "quux"},
"key_info": map[string]interface{}{
"foo": "alpha",
"bar": "beta",
"baz": "gamma",
"quux": "delta",
},
},
map[string]interface{}{
"keys": 4,
"key_info": 4,
},
},
{
"Unconventional other values in a list response are not touched",
map[string]interface{}{
"keys": []string{"foo", "bar"},
"something_else": "baz",
},
map[string]interface{}{
"keys": 2,
"something_else": "baz",
},
},
{
"Conventional values in a list response are not elided if their data types are unconventional",
map[string]interface{}{
"keys": map[string]interface{}{
"You wouldn't expect keys to be a map": nil,
},
"key_info": []string{
"You wouldn't expect key_info to be a slice",
},
},
map[string]interface{}{
"keys": map[string]interface{}{
"You wouldn't expect keys to be a map": nil,
},
"key_info": []string{
"You wouldn't expect key_info to be a slice",
},
},
},
}
oneInterestingTestCase := tests[2]
formatResponse := func(
t *testing.T,
config FormatterConfig,
operation logical.Operation,
inputData map[string]interface{},
) {
err := formatter.FormatResponse(ctx, io.Discard, config, &logical.LogInput{
Request: &logical.Request{Operation: operation},
Response: &logical.Response{Data: inputData},
})
require.Nil(t, err)
}
t.Run("Default case", func(t *testing.T) {
config := FormatterConfig{ElideListResponses: true}
for _, tc := range tests {
t.Run(tc.name, func(t *testing.T) {
formatResponse(t, config, logical.ListOperation, tc.inputData)
assert.Equal(t, tfw.hashExpectedValueForComparison(tc.expectedData), tfw.lastResponse.Response.Data)
})
}
})
t.Run("When Operation is not list, eliding does not happen", func(t *testing.T) {
config := FormatterConfig{ElideListResponses: true}
tc := oneInterestingTestCase
formatResponse(t, config, logical.ReadOperation, tc.inputData)
assert.Equal(t, tfw.hashExpectedValueForComparison(tc.inputData), tfw.lastResponse.Response.Data)
})
t.Run("When ElideListResponses is false, eliding does not happen", func(t *testing.T) {
config := FormatterConfig{ElideListResponses: false}
tc := oneInterestingTestCase
formatResponse(t, config, logical.ListOperation, tc.inputData)
assert.Equal(t, tfw.hashExpectedValueForComparison(tc.inputData), tfw.lastResponse.Response.Data)
})
t.Run("When Raw is true, eliding still happens", func(t *testing.T) {
config := FormatterConfig{ElideListResponses: true, Raw: true}
tc := oneInterestingTestCase
formatResponse(t, config, logical.ListOperation, tc.inputData)
assert.Equal(t, tc.expectedData, tfw.lastResponse.Response.Data)
})
}