pomerium/authorize/evaluator/headers_evaluator.go

110 lines
3 KiB
Go

package evaluator
import (
"context"
"fmt"
"net/http"
"github.com/open-policy-agent/opa/rego"
"github.com/pomerium/pomerium/authorize/evaluator/opa"
"github.com/pomerium/pomerium/config"
"github.com/pomerium/pomerium/internal/telemetry/trace"
"github.com/pomerium/pomerium/internal/urlutil"
)
// HeadersRequest is the input to the headers.rego script.
type HeadersRequest struct {
EnableGoogleCloudServerlessAuthentication bool `json:"enable_google_cloud_serverless_authentication"`
FromAudience string `json:"from_audience"`
KubernetesServiceAccountToken string `json:"kubernetes_service_account_token"`
ToAudience string `json:"to_audience"`
Session RequestSession `json:"session"`
}
// NewHeadersRequestFromPolicy creates a new HeadersRequest from a policy.
func NewHeadersRequestFromPolicy(policy *config.Policy) *HeadersRequest {
input := new(HeadersRequest)
input.EnableGoogleCloudServerlessAuthentication = policy.EnableGoogleCloudServerlessAuthentication
if u, err := urlutil.ParseAndValidateURL(policy.From); err == nil {
input.FromAudience = u.Hostname()
}
input.KubernetesServiceAccountToken = policy.KubernetesServiceAccountToken
for _, wu := range policy.To {
input.ToAudience = wu.URL.Hostname()
}
return input
}
// HeadersResponse is the output from the headers.rego script.
type HeadersResponse struct {
Headers http.Header
}
// A HeadersEvaluator evaluates the headers.rego script.
type HeadersEvaluator struct {
q rego.PreparedEvalQuery
}
// NewHeadersEvaluator creates a new HeadersEvaluator.
func NewHeadersEvaluator(ctx context.Context, store *Store) (*HeadersEvaluator, error) {
r := rego.New(
rego.Store(store),
rego.Module("pomerium.headers", opa.HeadersRego),
rego.Query("result = data.pomerium.headers"),
getGoogleCloudServerlessHeadersRegoOption,
store.GetDataBrokerRecordOption(),
)
q, err := r.PrepareForEval(ctx)
if err != nil {
return nil, err
}
return &HeadersEvaluator{
q: q,
}, nil
}
// Evaluate evaluates the headers.rego script.
func (e *HeadersEvaluator) Evaluate(ctx context.Context, req *HeadersRequest) (*HeadersResponse, error) {
_, span := trace.StartSpan(ctx, "authorize.HeadersEvaluator.Evaluate")
defer span.End()
rs, err := safeEval(ctx, e.q, rego.EvalInput(req))
if err != nil {
return nil, fmt.Errorf("authorize: error evaluating headers.rego: %w", err)
}
if len(rs) == 0 {
return nil, fmt.Errorf("authorize: unexpected empty result from evaluating headers.rego")
}
return &HeadersResponse{
Headers: e.getHeader(rs[0].Bindings),
}, nil
}
func (e *HeadersEvaluator) getHeader(vars rego.Vars) http.Header {
h := make(http.Header)
m, ok := vars["result"].(map[string]interface{})
if !ok {
return h
}
m, ok = m["identity_headers"].(map[string]interface{})
if !ok {
return h
}
for k := range m {
vs, ok := m[k].([]interface{})
if !ok {
continue
}
for _, v := range vs {
h.Add(k, fmt.Sprintf("%v", v))
}
}
return h
}