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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/x509_certificate.h"
     22 
     23 namespace net {
     24 
     25 namespace {
     26 
     27 // Maps X509_STORE_CTX_get_error() return values to our cert status flags.
     28 CertStatus MapCertErrorToCertStatus(int err) {
     29   switch (err) {
     30     case X509_V_ERR_SUBJECT_ISSUER_MISMATCH:
     31       return CERT_STATUS_COMMON_NAME_INVALID;
     32     case X509_V_ERR_CERT_NOT_YET_VALID:
     33     case X509_V_ERR_CERT_HAS_EXPIRED:
     34     case X509_V_ERR_CRL_NOT_YET_VALID:
     35     case X509_V_ERR_CRL_HAS_EXPIRED:
     36     case X509_V_ERR_ERROR_IN_CERT_NOT_BEFORE_FIELD:
     37     case X509_V_ERR_ERROR_IN_CERT_NOT_AFTER_FIELD:
     38     case X509_V_ERR_ERROR_IN_CRL_LAST_UPDATE_FIELD:
     39     case X509_V_ERR_ERROR_IN_CRL_NEXT_UPDATE_FIELD:
     40       return CERT_STATUS_DATE_INVALID;
     41     case X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT:
     42     case X509_V_ERR_UNABLE_TO_GET_CRL:
     43     case X509_V_ERR_INVALID_CA:
     44     case X509_V_ERR_UNABLE_TO_GET_CRL_ISSUER:
     45     case X509_V_ERR_INVALID_NON_CA:
     46     case X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT:
     47     case X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN:
     48     case X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY:
     49       return CERT_STATUS_AUTHORITY_INVALID;
     50 #if 0
     51 // TODO(bulach): what should we map to these status?
     52       return CERT_STATUS_NO_REVOCATION_MECHANISM;
     53       return CERT_STATUS_UNABLE_TO_CHECK_REVOCATION;
     54 #endif
     55     case X509_V_ERR_CERT_REVOKED:
     56       return CERT_STATUS_REVOKED;
     57     // All these status are mapped to CERT_STATUS_INVALID.
     58     case X509_V_ERR_UNABLE_TO_DECRYPT_CERT_SIGNATURE:
     59     case X509_V_ERR_UNABLE_TO_DECRYPT_CRL_SIGNATURE:
     60     case X509_V_ERR_UNABLE_TO_DECODE_ISSUER_PUBLIC_KEY:
     61     case X509_V_ERR_CERT_SIGNATURE_FAILURE:
     62     case X509_V_ERR_CRL_SIGNATURE_FAILURE:
     63     case X509_V_ERR_OUT_OF_MEM:
     64     case X509_V_ERR_UNABLE_TO_VERIFY_LEAF_SIGNATURE:
     65     case X509_V_ERR_CERT_CHAIN_TOO_LONG:
     66     case X509_V_ERR_PATH_LENGTH_EXCEEDED:
     67     case X509_V_ERR_INVALID_PURPOSE:
     68     case X509_V_ERR_CERT_UNTRUSTED:
     69     case X509_V_ERR_CERT_REJECTED:
     70     case X509_V_ERR_AKID_SKID_MISMATCH:
     71     case X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH:
     72     case X509_V_ERR_UNHANDLED_CRITICAL_EXTENSION:
     73     case X509_V_ERR_KEYUSAGE_NO_CERTSIGN:
     74     case X509_V_ERR_KEYUSAGE_NO_CRL_SIGN:
     75     case X509_V_ERR_UNHANDLED_CRITICAL_CRL_EXTENSION:
     76     case X509_V_ERR_PROXY_PATH_LENGTH_EXCEEDED:
     77     case X509_V_ERR_KEYUSAGE_NO_DIGITAL_SIGNATURE:
     78     case X509_V_ERR_PROXY_CERTIFICATES_NOT_ALLOWED:
     79     case X509_V_ERR_INVALID_EXTENSION:
     80     case X509_V_ERR_INVALID_POLICY_EXTENSION:
     81     case X509_V_ERR_NO_EXPLICIT_POLICY:
     82     case X509_V_ERR_UNNESTED_RESOURCE:
     83     case X509_V_ERR_APPLICATION_VERIFICATION:
     84       return CERT_STATUS_INVALID;
     85     default:
     86       NOTREACHED() << "Invalid X509 err " << err;
     87       return CERT_STATUS_INVALID;
     88   }
     89 }
     90 
     91 // sk_X509_free is a function-style macro, so can't be used as a template
     92 // param directly.
     93 void sk_X509_free_fn(STACK_OF(X509)* st) {
     94   sk_X509_free(st);
     95 }
     96 
     97 void GetCertChainInfo(X509_STORE_CTX* store_ctx,
     98                       CertVerifyResult* verify_result) {
     99   STACK_OF(X509)* chain = X509_STORE_CTX_get_chain(store_ctx);
    100   X509* verified_cert = NULL;
    101   std::vector<X509*> verified_chain;
    102   for (int i = 0; i < sk_X509_num(chain); ++i) {
    103     X509* cert = sk_X509_value(chain, i);
    104     if (i == 0) {
    105       verified_cert = cert;
    106     } else {
    107       verified_chain.push_back(cert);
    108     }
    109 
    110     // Only check the algorithm status for certificates that are not in the
    111     // trust store.
    112     if (i < store_ctx->last_untrusted) {
    113       int sig_alg = OBJ_obj2nid(cert->sig_alg->algorithm);
    114       if (sig_alg == NID_md2WithRSAEncryption) {
    115         verify_result->has_md2 = true;
    116       } else if (sig_alg == NID_md4WithRSAEncryption) {
    117         verify_result->has_md4 = true;
    118       } else if (sig_alg == NID_md5WithRSAEncryption) {
    119         verify_result->has_md5 = true;
    120       }
    121     }
    122   }
    123 
    124   if (verified_cert) {
    125     verify_result->verified_cert =
    126         X509Certificate::CreateFromHandle(verified_cert, verified_chain);
    127   }
    128 }
    129 
    130 void AppendPublicKeyHashes(X509_STORE_CTX* store_ctx,
    131                            HashValueVector* hashes) {
    132   STACK_OF(X509)* chain = X509_STORE_CTX_get_chain(store_ctx);
    133   for (int i = 0; i < sk_X509_num(chain); ++i) {
    134     X509* cert = sk_X509_value(chain, i);
    135 
    136     std::string der_data;
    137     if (!X509Certificate::GetDEREncoded(cert, &der_data))
    138       continue;
    139 
    140     base::StringPiece der_bytes(der_data);
    141     base::StringPiece spki_bytes;
    142     if (!asn1::ExtractSPKIFromDERCert(der_bytes, &spki_bytes))
    143       continue;
    144 
    145     HashValue sha1(HASH_VALUE_SHA1);
    146     base::SHA1HashBytes(reinterpret_cast<const uint8*>(spki_bytes.data()),
    147                         spki_bytes.size(), sha1.data());
    148     hashes->push_back(sha1);
    149 
    150     HashValue sha256(HASH_VALUE_SHA256);
    151     crypto::SHA256HashString(spki_bytes, sha256.data(), crypto::kSHA256Length);
    152     hashes->push_back(sha256);
    153   }
    154 }
    155 
    156 }  // namespace
    157 
    158 CertVerifyProcOpenSSL::CertVerifyProcOpenSSL() {}
    159 
    160 CertVerifyProcOpenSSL::~CertVerifyProcOpenSSL() {}
    161 
    162 bool CertVerifyProcOpenSSL::SupportsAdditionalTrustAnchors() const {
    163   return false;
    164 }
    165 
    166 int CertVerifyProcOpenSSL::VerifyInternal(
    167     X509Certificate* cert,
    168     const std::string& hostname,
    169     int flags,
    170     CRLSet* crl_set,
    171     const CertificateList& additional_trust_anchors,
    172     CertVerifyResult* verify_result) {
    173   crypto::EnsureOpenSSLInit();
    174 
    175   if (!cert->VerifyNameMatch(hostname))
    176     verify_result->cert_status |= CERT_STATUS_COMMON_NAME_INVALID;
    177 
    178   crypto::ScopedOpenSSL<X509_STORE_CTX, X509_STORE_CTX_free> ctx(
    179       X509_STORE_CTX_new());
    180 
    181   crypto::ScopedOpenSSL<STACK_OF(X509), sk_X509_free_fn> intermediates(
    182       sk_X509_new_null());
    183   if (!intermediates.get())
    184     return ERR_OUT_OF_MEMORY;
    185 
    186   const X509Certificate::OSCertHandles& os_intermediates =
    187       cert->GetIntermediateCertificates();
    188   for (X509Certificate::OSCertHandles::const_iterator it =
    189        os_intermediates.begin(); it != os_intermediates.end(); ++it) {
    190     if (!sk_X509_push(intermediates.get(), *it))
    191       return ERR_OUT_OF_MEMORY;
    192   }
    193   if (X509_STORE_CTX_init(ctx.get(), X509Certificate::cert_store(),
    194                           cert->os_cert_handle(), intermediates.get()) != 1) {
    195     NOTREACHED();
    196     return ERR_FAILED;
    197   }
    198 
    199   if (X509_verify_cert(ctx.get()) != 1) {
    200     int x509_error = X509_STORE_CTX_get_error(ctx.get());
    201     CertStatus cert_status = MapCertErrorToCertStatus(x509_error);
    202     LOG(ERROR) << "X509 Verification error "
    203         << X509_verify_cert_error_string(x509_error)
    204         << " : " << x509_error
    205         << " : " << X509_STORE_CTX_get_error_depth(ctx.get())
    206         << " : " << cert_status;
    207     verify_result->cert_status |= cert_status;
    208   }
    209 
    210   GetCertChainInfo(ctx.get(), verify_result);
    211   AppendPublicKeyHashes(ctx.get(), &verify_result->public_key_hashes);
    212   if (IsCertStatusError(verify_result->cert_status))
    213     return MapCertStatusToNetError(verify_result->cert_status);
    214 
    215   // Currently we only ues OpenSSL's default root CA paths, so treat all
    216   // correctly verified certs as being from a known root.
    217   // TODO(joth): if the motivations described in
    218   // http://src.chromium.org/viewvc/chrome?view=rev&revision=80778 become an
    219   // issue on OpenSSL builds, we will need to embed a hardcoded list of well
    220   // known root CAs, as per the _mac and _win versions.
    221   verify_result->is_issued_by_known_root = true;
    222 
    223   return OK;
    224 }
    225 
    226 }  // namespace net
    227