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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #include "net/cert/cert_verify_proc_openssl.h"
      6 
      7 #include <openssl/x509v3.h>
      8 
      9 #include <string>
     10 #include <vector>
     11 
     12 #include "base/logging.h"
     13 #include "base/sha1.h"
     14 #include "crypto/openssl_util.h"
     15 #include "crypto/sha2.h"
     16 #include "net/base/net_errors.h"
     17 #include "net/cert/asn1_util.h"
     18 #include "net/cert/cert_status_flags.h"
     19 #include "net/cert/cert_verifier.h"
     20 #include "net/cert/cert_verify_result.h"
     21 #include "net/cert/test_root_certs.h"
     22 #include "net/cert/x509_certificate.h"
     23 
     24 namespace net {
     25 
     26 namespace {
     27 
     28 // Maps X509_STORE_CTX_get_error() return values to our cert status flags.
     29 CertStatus MapCertErrorToCertStatus(int err) {
     30   switch (err) {
     31     case X509_V_ERR_SUBJECT_ISSUER_MISMATCH:
     32       return CERT_STATUS_COMMON_NAME_INVALID;
     33     case X509_V_ERR_CERT_NOT_YET_VALID:
     34     case X509_V_ERR_CERT_HAS_EXPIRED:
     35     case X509_V_ERR_CRL_NOT_YET_VALID:
     36     case X509_V_ERR_CRL_HAS_EXPIRED:
     37     case X509_V_ERR_ERROR_IN_CERT_NOT_BEFORE_FIELD:
     38     case X509_V_ERR_ERROR_IN_CERT_NOT_AFTER_FIELD:
     39     case X509_V_ERR_ERROR_IN_CRL_LAST_UPDATE_FIELD:
     40     case X509_V_ERR_ERROR_IN_CRL_NEXT_UPDATE_FIELD:
     41       return CERT_STATUS_DATE_INVALID;
     42     case X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT:
     43     case X509_V_ERR_UNABLE_TO_GET_CRL:
     44     case X509_V_ERR_INVALID_CA:
     45     case X509_V_ERR_UNABLE_TO_GET_CRL_ISSUER:
     46     case X509_V_ERR_INVALID_NON_CA:
     47     case X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT:
     48     case X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN:
     49     case X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY:
     50       return CERT_STATUS_AUTHORITY_INVALID;
     51 #if 0
     52 // TODO(bulach): what should we map to these status?
     53       return CERT_STATUS_NO_REVOCATION_MECHANISM;
     54       return CERT_STATUS_UNABLE_TO_CHECK_REVOCATION;
     55 #endif
     56     case X509_V_ERR_CERT_REVOKED:
     57       return CERT_STATUS_REVOKED;
     58     // All these status are mapped to CERT_STATUS_INVALID.
     59     case X509_V_ERR_UNABLE_TO_DECRYPT_CERT_SIGNATURE:
     60     case X509_V_ERR_UNABLE_TO_DECRYPT_CRL_SIGNATURE:
     61     case X509_V_ERR_UNABLE_TO_DECODE_ISSUER_PUBLIC_KEY:
     62     case X509_V_ERR_CERT_SIGNATURE_FAILURE:
     63     case X509_V_ERR_CRL_SIGNATURE_FAILURE:
     64     case X509_V_ERR_OUT_OF_MEM:
     65     case X509_V_ERR_UNABLE_TO_VERIFY_LEAF_SIGNATURE:
     66     case X509_V_ERR_CERT_CHAIN_TOO_LONG:
     67     case X509_V_ERR_PATH_LENGTH_EXCEEDED:
     68     case X509_V_ERR_INVALID_PURPOSE:
     69     case X509_V_ERR_CERT_UNTRUSTED:
     70     case X509_V_ERR_CERT_REJECTED:
     71     case X509_V_ERR_AKID_SKID_MISMATCH:
     72     case X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH:
     73     case X509_V_ERR_UNHANDLED_CRITICAL_EXTENSION:
     74     case X509_V_ERR_KEYUSAGE_NO_CERTSIGN:
     75     case X509_V_ERR_KEYUSAGE_NO_CRL_SIGN:
     76     case X509_V_ERR_UNHANDLED_CRITICAL_CRL_EXTENSION:
     77     case X509_V_ERR_PROXY_PATH_LENGTH_EXCEEDED:
     78     case X509_V_ERR_KEYUSAGE_NO_DIGITAL_SIGNATURE:
     79     case X509_V_ERR_PROXY_CERTIFICATES_NOT_ALLOWED:
     80     case X509_V_ERR_INVALID_EXTENSION:
     81     case X509_V_ERR_INVALID_POLICY_EXTENSION:
     82     case X509_V_ERR_NO_EXPLICIT_POLICY:
     83     case X509_V_ERR_UNNESTED_RESOURCE:
     84     case X509_V_ERR_APPLICATION_VERIFICATION:
     85       return CERT_STATUS_INVALID;
     86     default:
     87       NOTREACHED() << "Invalid X509 err " << err;
     88       return CERT_STATUS_INVALID;
     89   }
     90 }
     91 
     92 // sk_X509_free is a function-style macro, so can't be used as a template
     93 // param directly.
     94 void sk_X509_free_fn(STACK_OF(X509)* st) {
     95   sk_X509_free(st);
     96 }
     97 
     98 void GetCertChainInfo(X509_STORE_CTX* store_ctx,
     99                       CertVerifyResult* verify_result) {
    100   STACK_OF(X509)* chain = X509_STORE_CTX_get_chain(store_ctx);
    101   X509* verified_cert = NULL;
    102   std::vector<X509*> verified_chain;
    103   for (int i = 0; i < sk_X509_num(chain); ++i) {
    104     X509* cert = sk_X509_value(chain, i);
    105     if (i == 0) {
    106       verified_cert = cert;
    107     } else {
    108       verified_chain.push_back(cert);
    109     }
    110 
    111     // Only check the algorithm status for certificates that are not in the
    112     // trust store.
    113     if (i < store_ctx->last_untrusted) {
    114       int sig_alg = OBJ_obj2nid(cert->sig_alg->algorithm);
    115       if (sig_alg == NID_md2WithRSAEncryption) {
    116         verify_result->has_md2 = true;
    117       } else if (sig_alg == NID_md4WithRSAEncryption) {
    118         verify_result->has_md4 = true;
    119       } else if (sig_alg == NID_md5WithRSAEncryption) {
    120         verify_result->has_md5 = true;
    121       }
    122     }
    123   }
    124 
    125   // Set verify_result->verified_cert and
    126   // verify_result->is_issued_by_known_root.
    127   if (verified_cert) {
    128     verify_result->verified_cert =
    129         X509Certificate::CreateFromHandle(verified_cert, verified_chain);
    130 
    131     // For OpenSSL builds, only certificates used for unit tests are treated
    132     // as not issued by known roots. The only way to determine whether a
    133     // certificate is issued by a known root using OpenSSL is to examine
    134     // distro-and-release specific hardcoded lists.
    135     verify_result->is_issued_by_known_root = true;
    136     if (TestRootCerts::HasInstance()) {
    137       X509* root = NULL;
    138       if (verified_chain.empty()) {
    139         root = verified_cert;
    140       } else {
    141         root = verified_chain.back();
    142       }
    143       TestRootCerts* root_certs = TestRootCerts::GetInstance();
    144       if (root_certs->Contains(root))
    145           verify_result->is_issued_by_known_root = false;
    146     }
    147   }
    148 }
    149 
    150 void AppendPublicKeyHashes(X509_STORE_CTX* store_ctx,
    151                            HashValueVector* hashes) {
    152   STACK_OF(X509)* chain = X509_STORE_CTX_get_chain(store_ctx);
    153   for (int i = 0; i < sk_X509_num(chain); ++i) {
    154     X509* cert = sk_X509_value(chain, i);
    155 
    156     std::string der_data;
    157     if (!X509Certificate::GetDEREncoded(cert, &der_data))
    158       continue;
    159 
    160     base::StringPiece der_bytes(der_data);
    161     base::StringPiece spki_bytes;
    162     if (!asn1::ExtractSPKIFromDERCert(der_bytes, &spki_bytes))
    163       continue;
    164 
    165     HashValue sha1(HASH_VALUE_SHA1);
    166     base::SHA1HashBytes(reinterpret_cast<const uint8*>(spki_bytes.data()),
    167                         spki_bytes.size(), sha1.data());
    168     hashes->push_back(sha1);
    169 
    170     HashValue sha256(HASH_VALUE_SHA256);
    171     crypto::SHA256HashString(spki_bytes, sha256.data(), crypto::kSHA256Length);
    172     hashes->push_back(sha256);
    173   }
    174 }
    175 
    176 }  // namespace
    177 
    178 CertVerifyProcOpenSSL::CertVerifyProcOpenSSL() {}
    179 
    180 CertVerifyProcOpenSSL::~CertVerifyProcOpenSSL() {}
    181 
    182 bool CertVerifyProcOpenSSL::SupportsAdditionalTrustAnchors() const {
    183   return false;
    184 }
    185 
    186 int CertVerifyProcOpenSSL::VerifyInternal(
    187     X509Certificate* cert,
    188     const std::string& hostname,
    189     int flags,
    190     CRLSet* crl_set,
    191     const CertificateList& additional_trust_anchors,
    192     CertVerifyResult* verify_result) {
    193   crypto::EnsureOpenSSLInit();
    194 
    195   if (!cert->VerifyNameMatch(hostname,
    196                              &verify_result->common_name_fallback_used)) {
    197     verify_result->cert_status |= CERT_STATUS_COMMON_NAME_INVALID;
    198   }
    199 
    200   crypto::ScopedOpenSSL<X509_STORE_CTX, X509_STORE_CTX_free> ctx(
    201       X509_STORE_CTX_new());
    202 
    203   crypto::ScopedOpenSSL<STACK_OF(X509), sk_X509_free_fn> intermediates(
    204       sk_X509_new_null());
    205   if (!intermediates.get())
    206     return ERR_OUT_OF_MEMORY;
    207 
    208   const X509Certificate::OSCertHandles& os_intermediates =
    209       cert->GetIntermediateCertificates();
    210   for (X509Certificate::OSCertHandles::const_iterator it =
    211        os_intermediates.begin(); it != os_intermediates.end(); ++it) {
    212     if (!sk_X509_push(intermediates.get(), *it))
    213       return ERR_OUT_OF_MEMORY;
    214   }
    215   if (X509_STORE_CTX_init(ctx.get(), X509Certificate::cert_store(),
    216                           cert->os_cert_handle(), intermediates.get()) != 1) {
    217     NOTREACHED();
    218     return ERR_FAILED;
    219   }
    220 
    221   if (X509_verify_cert(ctx.get()) != 1) {
    222     int x509_error = X509_STORE_CTX_get_error(ctx.get());
    223     CertStatus cert_status = MapCertErrorToCertStatus(x509_error);
    224     LOG(ERROR) << "X509 Verification error "
    225         << X509_verify_cert_error_string(x509_error)
    226         << " : " << x509_error
    227         << " : " << X509_STORE_CTX_get_error_depth(ctx.get())
    228         << " : " << cert_status;
    229     verify_result->cert_status |= cert_status;
    230   }
    231 
    232   GetCertChainInfo(ctx.get(), verify_result);
    233   AppendPublicKeyHashes(ctx.get(), &verify_result->public_key_hashes);
    234   if (IsCertStatusError(verify_result->cert_status))
    235     return MapCertStatusToNetError(verify_result->cert_status);
    236 
    237   return OK;
    238 }
    239 
    240 }  // namespace net
    241