verify_certificate_chain.cc | Explore in Territory

// Copyright 2015 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "verify_certificate_chain.h"

#include <algorithm>
#include <cassert>

#include <openssl/base.h>
#include "cert_error_params.h"
#include "cert_errors.h"
#include "common_cert_errors.h"
#include "extended_key_usage.h"
#include "input.h"
#include "name_constraints.h"
#include "parse_certificate.h"
#include "signature_algorithm.h"
#include "trust_store.h"
#include "verify_signed_data.h"

BSSL_NAMESPACE_BEGIN

namespace {

bool IsHandledCriticalExtension(const ParsedExtension &extension,
                                const ParsedCertificate &cert) { … }

// Adds errors to |errors| if the certificate contains unconsumed _critical_
// extensions.
void VerifyNoUnconsumedCriticalExtensions(const ParsedCertificate &cert,
                                          CertErrors *errors,
                                          bool allow_precertificate) { … }

// Returns true if |cert| was self-issued. The definition of self-issuance
// comes from RFC 5280 section 6.1:
//
//    A certificate is self-issued if the same DN appears in the subject
//    and issuer fields (the two DNs are the same if they match according
//    to the rules specified in Section 7.1).  In general, the issuer and
//    subject of the certificates that make up a path are different for
//    each certificate.  However, a CA may issue a certificate to itself to
//    support key rollover or changes in certificate policies.  These
//    self-issued certificates are not counted when evaluating path length
//    or name constraints.
[[nodiscard]] bool IsSelfIssued(const ParsedCertificate &cert) { … }

// Adds errors to |errors| if |cert| is not valid at time |time|.
//
// The certificate's validity requirements are described by RFC 5280 section
// 4.1.2.5:
//
//    The validity period for a certificate is the period of time from
//    notBefore through notAfter, inclusive.
void VerifyTimeValidity(const ParsedCertificate &cert,
                        const der::GeneralizedTime &time, CertErrors *errors) { … }

// Adds errors to |errors| if |cert| has internally inconsistent signature
// algorithms.
//
// X.509 certificates contain two different signature algorithms:
//  (1) The signatureAlgorithm field of Certificate
//  (2) The signature field of TBSCertificate
//
// According to RFC 5280 section 4.1.1.2 and 4.1.2.3 these two fields must be
// equal:
//
//     This field MUST contain the same algorithm identifier as the
//     signature field in the sequence tbsCertificate (Section 4.1.2.3).
//
// The spec is not explicit about what "the same algorithm identifier" means.
// Our interpretation is that the two DER-encoded fields must be byte-for-byte
// identical.
//
// In practice however there are certificates which use different encodings for
// specifying RSA with SHA1 (different OIDs). This is special-cased for
// compatibility sake.
bool VerifySignatureAlgorithmsMatch(const ParsedCertificate &cert,
                                    CertErrors *errors) { … }

// Verify that |cert| can be used for |required_key_purpose|.
void VerifyExtendedKeyUsage(const ParsedCertificate &cert,
                            KeyPurpose required_key_purpose, CertErrors *errors,
                            bool is_target_cert, bool is_target_cert_issuer) { … }

// Representation of RFC 5280's "valid_policy_tree", used to keep track of the
// valid policies and policy re-mappings. This structure is defined in
// section 6.1.2.
//
// ValidPolicyGraph differs from RFC 5280's description in that:
//
//  (1) It does not track "qualifier_set". This is not needed as it is not
//      output by this implementation.
//
//  (2) It builds a directed acyclic graph, rather than a tree. When a given
//      policy matches multiple parents, RFC 5280 makes a separate node for
//      each parent. This representation condenses them into one node with
//      multiple parents.
//
//  (3) It does not track "expected_policy_set" or anyPolicy nodes directly.
//      Rather it maintains, only for the most recent level, whether there is an
//      anyPolicy node and an inverted map of all "expected_policy_set" values.
//
//  (4) Some pruning steps are deferred to when policies are evaluated, as a
//      reachability pass.
class ValidPolicyGraph { … };

// Class that encapsulates the state variables used by certificate path
// validation.
class PathVerifier { … };

void PathVerifier::VerifyPolicies(const ParsedCertificate &cert,
                                  bool is_target_cert, CertErrors *errors) { … }

void PathVerifier::VerifyPolicyMappings(const ParsedCertificate &cert,
                                        CertErrors *errors) { … }

void PathVerifier::ApplyPolicyConstraints(const ParsedCertificate &cert) { … }

void PathVerifier::BasicCertificateProcessing(
    const ParsedCertificate &cert, bool is_target_cert,
    bool is_target_cert_issuer, const der::GeneralizedTime &time,
    KeyPurpose required_key_purpose, CertErrors *errors,
    bool *shortcircuit_chain_validation) { … }

void PathVerifier::PrepareForNextCertificate(const ParsedCertificate &cert,
                                             CertErrors *errors) { … }

// Checks if the target certificate has the CA bit set. If it does, add
// the appropriate error or warning to |errors|.
void VerifyTargetCertIsNotCA(const ParsedCertificate &cert,
                             KeyPurpose required_key_purpose,
                             CertErrors *errors) { … }

void PathVerifier::WrapUp(const ParsedCertificate &cert,
                          KeyPurpose required_key_purpose,
                          const std::set<der::Input> &user_initial_policy_set,
                          bool allow_precertificate,
                          CertErrors * errors) { … }

void PathVerifier::ApplyTrustAnchorConstraints(const ParsedCertificate &cert,
                                               KeyPurpose required_key_purpose,
                                               CertErrors *errors) { … }

void PathVerifier::ProcessRootCertificate(const ParsedCertificate &cert,
                                          const CertificateTrust &trust,
                                          const der::GeneralizedTime &time,
                                          KeyPurpose required_key_purpose,
                                          CertErrors *errors,
                                          bool *shortcircuit_chain_validation) { … }

void PathVerifier::ProcessSingleCertChain(const ParsedCertificate &cert,
                                          const CertificateTrust &trust,
                                          const der::GeneralizedTime &time,
                                          KeyPurpose required_key_purpose,
                                          CertErrors *errors) { … }

bssl::UniquePtr<EVP_PKEY> PathVerifier::ParseAndCheckPublicKey(
    der::Input spki, CertErrors *errors) { … }

void PathVerifier::Run(
    const ParsedCertificateList &certs, const CertificateTrust &last_cert_trust,
    VerifyCertificateChainDelegate *delegate, const der::GeneralizedTime &time,
    KeyPurpose required_key_purpose,
    InitialExplicitPolicy initial_explicit_policy,
    const std::set<der::Input> &user_initial_policy_set,
    InitialPolicyMappingInhibit initial_policy_mapping_inhibit,
    InitialAnyPolicyInhibit initial_any_policy_inhibit,
    std::set<der::Input> *user_constrained_policy_set, CertPathErrors *errors) { … }

}  // namespace

VerifyCertificateChainDelegate::~VerifyCertificateChainDelegate() = default;

void VerifyCertificateChain(
    const ParsedCertificateList &certs, const CertificateTrust &last_cert_trust,
    VerifyCertificateChainDelegate *delegate, const der::GeneralizedTime &time,
    KeyPurpose required_key_purpose,
    InitialExplicitPolicy initial_explicit_policy,
    const std::set<der::Input> &user_initial_policy_set,
    InitialPolicyMappingInhibit initial_policy_mapping_inhibit,
    InitialAnyPolicyInhibit initial_any_policy_inhibit,
    std::set<der::Input> *user_constrained_policy_set, CertPathErrors *errors) { … }

bool VerifyCertificateIsSelfSigned(const ParsedCertificate &cert,
                                   SignatureVerifyCache *cache,
                                   CertErrors *errors) { … }

BSSL_NAMESPACE_END
chromium/third_party/boringssl/src/pki/verify_certificate_chain.cc
