/
evaluator.go
257 lines (218 loc) · 7.02 KB
/
evaluator.go
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// Package evaluator contains rego evaluators for evaluating authorize policy.
package evaluator
import (
"context"
"encoding/base64"
"fmt"
"net/http"
"net/url"
"github.com/go-jose/go-jose/v3"
"github.com/open-policy-agent/opa/rego"
"github.com/pomerium/pomerium/config"
"github.com/pomerium/pomerium/internal/httputil"
"github.com/pomerium/pomerium/internal/log"
"github.com/pomerium/pomerium/internal/telemetry/trace"
"github.com/pomerium/pomerium/internal/urlutil"
"github.com/pomerium/pomerium/pkg/cryptutil"
"github.com/pomerium/pomerium/pkg/policy/criteria"
)
// notFoundOutput is what's returned if a route isn't found for a policy.
var notFoundOutput = &Result{
Deny: NewRuleResult(true, criteria.ReasonRouteNotFound),
Headers: make(http.Header),
}
// Request contains the inputs needed for evaluation.
type Request struct {
Policy *config.Policy
HTTP RequestHTTP
Session RequestSession
}
// RequestHTTP is the HTTP field in the request.
type RequestHTTP struct {
Method string `json:"method"`
Path string `json:"path"`
URL string `json:"url"`
Headers map[string]string `json:"headers"`
ClientCertificate string `json:"client_certificate"`
}
// NewRequestHTTP creates a new RequestHTTP.
func NewRequestHTTP(method string, requestURL url.URL, headers map[string]string, rawClientCertificate string) RequestHTTP {
return RequestHTTP{
Method: method,
Path: requestURL.Path,
URL: requestURL.String(),
Headers: headers,
ClientCertificate: rawClientCertificate,
}
}
// RequestSession is the session field in the request.
type RequestSession struct {
ID string `json:"id"`
}
// Result is the result of evaluation.
type Result struct {
Allow RuleResult
Deny RuleResult
Headers http.Header
DataBrokerServerVersion, DataBrokerRecordVersion uint64
}
// An Evaluator evaluates policies.
type Evaluator struct {
store *Store
policyEvaluators map[uint64]*PolicyEvaluator
headersEvaluators *HeadersEvaluator
clientCA []byte
}
// New creates a new Evaluator.
func New(ctx context.Context, store *Store, options ...Option) (*Evaluator, error) {
e := &Evaluator{store: store}
cfg := getConfig(options...)
err := e.updateStore(cfg)
if err != nil {
return nil, err
}
e.headersEvaluators, err = NewHeadersEvaluator(ctx, store)
if err != nil {
return nil, err
}
e.policyEvaluators = make(map[uint64]*PolicyEvaluator)
for _, configPolicy := range cfg.policies {
id, err := configPolicy.RouteID()
if err != nil {
return nil, fmt.Errorf("authorize: error computing policy route id: %w", err)
}
policyEvaluator, err := NewPolicyEvaluator(ctx, store, &configPolicy) //nolint
if err != nil {
return nil, err
}
e.policyEvaluators[id] = policyEvaluator
}
e.clientCA = cfg.clientCA
return e, nil
}
// Evaluate evaluates the rego for the given policy and generates the identity headers.
func (e *Evaluator) Evaluate(ctx context.Context, req *Request) (*Result, error) {
_, span := trace.StartSpan(ctx, "authorize.Evaluator.Evaluate")
defer span.End()
if req.Policy == nil {
return notFoundOutput, nil
}
id, err := req.Policy.RouteID()
if err != nil {
return nil, fmt.Errorf("authorize: error computing policy route id: %w", err)
}
policyEvaluator, ok := e.policyEvaluators[id]
if !ok {
return notFoundOutput, nil
}
clientCA, err := e.getClientCA(req.Policy)
if err != nil {
return nil, err
}
isValidClientCertificate, err := isValidClientCertificate(clientCA, req.HTTP.ClientCertificate)
if err != nil {
return nil, fmt.Errorf("authorize: error validating client certificate: %w", err)
}
policyOutput, err := policyEvaluator.Evaluate(ctx, &PolicyRequest{
HTTP: req.HTTP,
Session: req.Session,
IsValidClientCertificate: isValidClientCertificate,
})
if err != nil {
return nil, err
}
headersReq := NewHeadersRequestFromPolicy(req.Policy)
headersReq.Session = req.Session
headersOutput, err := e.headersEvaluators.Evaluate(ctx, headersReq)
if err != nil {
return nil, err
}
carryOverJWTAssertion(headersOutput.Headers, req.HTTP.Headers)
res := &Result{
Allow: policyOutput.Allow,
Deny: policyOutput.Deny,
Headers: headersOutput.Headers,
}
res.DataBrokerServerVersion, res.DataBrokerRecordVersion = e.store.GetDataBrokerVersions()
return res, nil
}
func (e *Evaluator) getClientCA(policy *config.Policy) (string, error) {
if policy != nil && policy.TLSDownstreamClientCA != "" {
bs, err := base64.StdEncoding.DecodeString(policy.TLSDownstreamClientCA)
if err != nil {
return "", err
}
return string(bs), nil
}
return string(e.clientCA), nil
}
func (e *Evaluator) updateStore(cfg *evaluatorConfig) error {
jwk, err := getJWK(cfg)
if err != nil {
return fmt.Errorf("authorize: couldn't create signer: %w", err)
}
authenticateURL, err := urlutil.ParseAndValidateURL(cfg.authenticateURL)
if err != nil {
return fmt.Errorf("authorize: invalid authenticate URL: %w", err)
}
e.store.UpdateIssuer(authenticateURL.Host)
e.store.UpdateGoogleCloudServerlessAuthenticationServiceAccount(
cfg.googleCloudServerlessAuthenticationServiceAccount,
)
e.store.UpdateJWTClaimHeaders(cfg.jwtClaimsHeaders)
e.store.UpdateRoutePolicies(cfg.policies)
e.store.UpdateSigningKey(jwk)
return nil
}
func getJWK(cfg *evaluatorConfig) (*jose.JSONWebKey, error) {
var decodedCert []byte
// if we don't have a signing key, generate one
if cfg.signingKey == "" {
key, err := cryptutil.NewSigningKey()
if err != nil {
return nil, fmt.Errorf("couldn't generate signing key: %w", err)
}
decodedCert, err = cryptutil.EncodePrivateKey(key)
if err != nil {
return nil, fmt.Errorf("bad signing key: %w", err)
}
} else {
var err error
decodedCert, err = base64.StdEncoding.DecodeString(cfg.signingKey)
if err != nil {
return nil, fmt.Errorf("bad signing key: %w", err)
}
}
jwk, err := cryptutil.PrivateJWKFromBytes(decodedCert)
if err != nil {
return nil, fmt.Errorf("couldn't generate signing key: %w", err)
}
log.Info(context.TODO()).Str("Algorithm", jwk.Algorithm).
Str("KeyID", jwk.KeyID).
Interface("Public Key", jwk.Public()).
Msg("authorize: signing key")
return jwk, nil
}
func safeEval(ctx context.Context, q rego.PreparedEvalQuery, options ...rego.EvalOption) (resultSet rego.ResultSet, err error) {
defer func() {
if e := recover(); e != nil {
err = fmt.Errorf("%v", e)
}
}()
resultSet, err = q.Eval(ctx, options...)
return resultSet, err
}
// carryOverJWTAssertion copies assertion JWT from request to response
// note that src keys are expected to be http.CanonicalHeaderKey
func carryOverJWTAssertion(dst http.Header, src map[string]string) {
jwtForKey := http.CanonicalHeaderKey(httputil.HeaderPomeriumJWTAssertionFor)
jwtFor, ok := src[jwtForKey]
if ok && jwtFor != "" {
dst.Add(jwtForKey, jwtFor)
return
}
jwtFor, ok = src[http.CanonicalHeaderKey(httputil.HeaderPomeriumJWTAssertion)]
if ok && jwtFor != "" {
dst.Add(jwtForKey, jwtFor)
}
}