Files
vault/audit/entry_filter.go
Peter Wilson 8bee54c89d VAULT-24452: audit refactor (#26460)
* Refactor audit code into audit package
* remove builtin/audit
* removed unrequired files
2024-04-18 08:25:04 +01:00

104 lines
2.8 KiB
Go

// Copyright (c) HashiCorp, Inc.
// SPDX-License-Identifier: BUSL-1.1
package audit
import (
"context"
"fmt"
"strings"
"github.com/hashicorp/eventlogger"
"github.com/hashicorp/go-bexpr"
"github.com/hashicorp/vault/helper/namespace"
"github.com/hashicorp/vault/sdk/logical"
)
var _ eventlogger.Node = (*entryFilter)(nil)
// entryFilter should be used to filter audit requests and responses which should
// make it to a sink.
type entryFilter struct {
// the evaluator for the bexpr expression that should be applied by the node.
evaluator *bexpr.Evaluator
}
// newEntryFilter should be used to create an entryFilter node.
// The filter supplied should be in bexpr format and reference fields from logical.LogInputBexpr.
func newEntryFilter(filter string) (*entryFilter, error) {
filter = strings.TrimSpace(filter)
if filter == "" {
return nil, fmt.Errorf("cannot create new audit filter with empty filter expression: %w", ErrExternalOptions)
}
eval, err := bexpr.CreateEvaluator(filter)
if err != nil {
return nil, fmt.Errorf("cannot create new audit filter: %w: %w", ErrExternalOptions, err)
}
// Validate the filter by attempting to evaluate it with an empty input.
// This prevents users providing a filter with a field that would error during
// matching, and block all auditable requests to Vault.
li := logical.LogInputBexpr{}
_, err = eval.Evaluate(li)
if err != nil {
return nil, fmt.Errorf("filter references an unsupported field: %s: %w", filter, ErrExternalOptions)
}
return &entryFilter{evaluator: eval}, nil
}
// Reopen is a no-op for the filter node.
func (*entryFilter) Reopen() error {
return nil
}
// Type describes the type of this node (filter).
func (*entryFilter) Type() eventlogger.NodeType {
return eventlogger.NodeTypeFilter
}
// Process will attempt to parse the incoming event data and decide whether it
// should be filtered or remain in the pipeline and passed to the next node.
func (f *entryFilter) Process(ctx context.Context, e *eventlogger.Event) (*eventlogger.Event, error) {
select {
case <-ctx.Done():
return nil, ctx.Err()
default:
}
if e == nil {
return nil, fmt.Errorf("event is nil: %w", ErrInvalidParameter)
}
a, ok := e.Payload.(*AuditEvent)
if !ok {
return nil, fmt.Errorf("cannot parse event payload: %w", ErrInvalidParameter)
}
// If we don't have data to process, then we're done.
if a.Data == nil {
return nil, nil
}
ns, err := namespace.FromContext(ctx)
if err != nil {
return nil, fmt.Errorf("cannot obtain namespace: %w", err)
}
datum := a.Data.BexprDatum(ns.Path)
result, err := f.evaluator.Evaluate(datum)
if err != nil {
return nil, fmt.Errorf("unable to evaluate filter: %w", err)
}
if result {
// Allow this event to carry on through the pipeline.
return e, nil
}
// End process of this pipeline.
return nil, nil
}