// Copyright (c) 2011 The Chromium Authors. All rights reserved. // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. #include "net/base/x509_certificate.h" #include #include #include #include #include #include "base/lazy_instance.h" #include "base/logging.h" #include "base/memory/singleton.h" #include "base/metrics/histogram.h" #include "base/pickle.h" #include "base/sha1.h" #include "base/string_piece.h" #include "base/string_util.h" #include "base/synchronization/lock.h" #include "base/time.h" #include "googleurl/src/url_canon_ip.h" #include "net/base/cert_status_flags.h" #include "net/base/cert_verify_result.h" #include "net/base/net_errors.h" #include "net/base/net_util.h" #include "net/base/pem_tokenizer.h" namespace net { namespace { // Returns true if this cert fingerprint is the null (all zero) fingerprint. // We use this as a bogus fingerprint value. bool IsNullFingerprint(const SHA1Fingerprint& fingerprint) { for (size_t i = 0; i < arraysize(fingerprint.data); ++i) { if (fingerprint.data[i] != 0) return false; } return true; } // Indicates the order to use when trying to decode binary data, which is // based on (speculation) as to what will be most common -> least common const X509Certificate::Format kFormatDecodePriority[] = { X509Certificate::FORMAT_SINGLE_CERTIFICATE, X509Certificate::FORMAT_PKCS7 }; // The PEM block header used for DER certificates const char kCertificateHeader[] = "CERTIFICATE"; // The PEM block header used for PKCS#7 data const char kPKCS7Header[] = "PKCS7"; // A thread-safe cache for OS certificate handles. // // Within each of the supported underlying crypto libraries, a certificate // handle is represented as a ref-counted object that contains the parsed // data for the certificate. In addition, the underlying OS handle may also // contain a copy of the original ASN.1 DER used to constructed the handle. // // In order to reduce the memory usage when multiple SSL connections exist, // with each connection storing the server's identity certificate plus any // intermediates supplied, the certificate handles are cached. Any two // X509Certificates that were created from the same ASN.1 DER data, // regardless of where that data came from, will share the same underlying // OS certificate handle. class X509CertificateCache { public: // Performs a compare-and-swap like operation. If an OS certificate handle // for the same certificate data as |*cert_handle| already exists in the // cache, the original |*cert_handle| will be freed and |cert_handle| // will be updated to point to a duplicated reference to the existing cached // certificate, with the caller taking ownership of this duplicated handle. // If an equivalent OS certificate handle is not found, a duplicated // reference to |*cert_handle| will be added to the cache. In either case, // upon return, the caller fully owns |*cert_handle| and is responsible for // calling FreeOSCertHandle(), after first calling Remove(). void InsertOrUpdate(X509Certificate::OSCertHandle* cert_handle); // Decrements the cache reference count for |cert_handle|, a handle that was // previously obtained by calling InsertOrUpdate(). If this is the last // cached reference held, this will remove the handle from the cache. The // caller retains ownership of |cert_handle| and remains responsible for // calling FreeOSCertHandle() to release the underlying OS certificate void Remove(X509Certificate::OSCertHandle cert_handle); private: // A single entry in the cache. Certificates will be keyed by their SHA1 // fingerprints, but will not be considered equivalent unless the entire // certificate data matches. struct Entry { Entry() : cert_handle(NULL), ref_count(0) {} X509Certificate::OSCertHandle cert_handle; // Increased by each call to InsertOrUpdate(), and balanced by each call // to Remove(). When it equals 0, all references created by // InsertOrUpdate() have been released, so the cache entry will be removed // the cached OS certificate handle will be freed. int ref_count; }; typedef std::map CertMap; // Obtain an instance of X509CertificateCache via a LazyInstance. X509CertificateCache() {} ~X509CertificateCache() {} friend struct base::DefaultLazyInstanceTraits; // You must acquire this lock before using any private data of this object // You must not block while holding this lock. base::Lock lock_; // The certificate cache. You must acquire |lock_| before using |cache_|. CertMap cache_; DISALLOW_COPY_AND_ASSIGN(X509CertificateCache); }; base::LazyInstance > g_x509_certificate_cache(base::LINKER_INITIALIZED); void X509CertificateCache::InsertOrUpdate( X509Certificate::OSCertHandle* cert_handle) { DCHECK(cert_handle); SHA1Fingerprint fingerprint = X509Certificate::CalculateFingerprint(*cert_handle); X509Certificate::OSCertHandle old_handle = NULL; { base::AutoLock lock(lock_); CertMap::iterator pos = cache_.find(fingerprint); if (pos == cache_.end()) { // A cached entry was not found, so initialize a new entry. The entry // assumes ownership of the current |*cert_handle|. Entry cache_entry; cache_entry.cert_handle = *cert_handle; cache_entry.ref_count = 0; CertMap::value_type cache_value(fingerprint, cache_entry); pos = cache_.insert(cache_value).first; } else { bool is_same_cert = X509Certificate::IsSameOSCert(*cert_handle, pos->second.cert_handle); if (!is_same_cert) { // Two certificates don't match, due to a SHA1 hash collision. Given // the low probability, the simplest solution is to not cache the // certificate, which should not affect performance too negatively. return; } // A cached entry was found and will be used instead of the caller's // handle. Ensure the caller's original handle will be freed, since // ownership is assumed. old_handle = *cert_handle; } // Whether an existing cached handle or a new handle, increment the // cache's reference count and return a handle that the caller can own. ++pos->second.ref_count; *cert_handle = X509Certificate::DupOSCertHandle(pos->second.cert_handle); } // If the caller's handle was replaced with a cached handle, free the // original handle now. This is done outside of the lock because // |old_handle| may be the only handle for this particular certificate, so // freeing it may be complex or resource-intensive and does not need to // be guarded by the lock. if (old_handle) { X509Certificate::FreeOSCertHandle(old_handle); DHISTOGRAM_COUNTS("X509CertificateReuseCount", 1); } } void X509CertificateCache::Remove(X509Certificate::OSCertHandle cert_handle) { SHA1Fingerprint fingerprint = X509Certificate::CalculateFingerprint(cert_handle); base::AutoLock lock(lock_); CertMap::iterator pos = cache_.find(fingerprint); if (pos == cache_.end()) return; // A hash collision where the winning cert was already freed. bool is_same_cert = X509Certificate::IsSameOSCert(cert_handle, pos->second.cert_handle); if (!is_same_cert) return; // A hash collision where the winning cert is still around. if (--pos->second.ref_count == 0) { // The last reference to |cert_handle| has been removed, so release the // Entry's OS handle and remove the Entry. The caller still holds a // reference to |cert_handle| and is responsible for freeing it. X509Certificate::FreeOSCertHandle(pos->second.cert_handle); cache_.erase(pos); } } // CompareSHA1Hashes is a helper function for using bsearch() with an array of // SHA1 hashes. int CompareSHA1Hashes(const void* a, const void* b) { return memcmp(a, b, base::SHA1_LENGTH); } // Utility to split |src| on the first occurrence of |c|, if any. |right| will // either be empty if |c| was not found, or will contain the remainder of the // string including the split character itself. void SplitOnChar(const base::StringPiece& src, char c, base::StringPiece* left, base::StringPiece* right) { size_t pos = src.find(c); if (pos == base::StringPiece::npos) { *left = src; right->clear(); } else { *left = src.substr(0, pos); *right = src.substr(pos); } } #if defined(OS_WIN) X509Certificate::OSCertHandle CreateOSCert(base::StringPiece der_cert) { X509Certificate::OSCertHandle cert_handle = NULL; BOOL ok = CertAddEncodedCertificateToStore( X509Certificate::cert_store(), X509_ASN_ENCODING | PKCS_7_ASN_ENCODING, reinterpret_cast(der_cert.data()), der_cert.size(), CERT_STORE_ADD_USE_EXISTING, &cert_handle); return ok ? cert_handle : NULL; } #else X509Certificate::OSCertHandle CreateOSCert(base::StringPiece der_cert) { return X509Certificate::CreateOSCertHandleFromBytes( const_cast(der_cert.data()), der_cert.size()); } #endif } // namespace bool X509Certificate::LessThan::operator()(X509Certificate* lhs, X509Certificate* rhs) const { if (lhs == rhs) return false; SHA1FingerprintLessThan fingerprint_functor; return fingerprint_functor(lhs->fingerprint_, rhs->fingerprint_); } X509Certificate::X509Certificate(const std::string& subject, const std::string& issuer, base::Time start_date, base::Time expiration_date) : subject_(subject), issuer_(issuer), valid_start_(start_date), valid_expiry_(expiration_date), cert_handle_(NULL) { memset(fingerprint_.data, 0, sizeof(fingerprint_.data)); } // static X509Certificate* X509Certificate::CreateFromHandle( OSCertHandle cert_handle, const OSCertHandles& intermediates) { DCHECK(cert_handle); return new X509Certificate(cert_handle, intermediates); } // static X509Certificate* X509Certificate::CreateFromDERCertChain( const std::vector& der_certs) { if (der_certs.empty()) return NULL; X509Certificate::OSCertHandles intermediate_ca_certs; for (size_t i = 1; i < der_certs.size(); i++) { OSCertHandle handle = CreateOSCert(der_certs[i]); if (!handle) break; intermediate_ca_certs.push_back(handle); } OSCertHandle handle = NULL; // Return NULL if we failed to parse any of the certs. if (der_certs.size() - 1 == intermediate_ca_certs.size()) handle = CreateOSCert(der_certs[0]); X509Certificate* cert = NULL; if (handle) { cert = CreateFromHandle(handle, intermediate_ca_certs); FreeOSCertHandle(handle); } for (size_t i = 0; i < intermediate_ca_certs.size(); i++) FreeOSCertHandle(intermediate_ca_certs[i]); return cert; } // static X509Certificate* X509Certificate::CreateFromBytes(const char* data, int length) { OSCertHandle cert_handle = CreateOSCertHandleFromBytes(data, length); if (!cert_handle) return NULL; X509Certificate* cert = CreateFromHandle(cert_handle, OSCertHandles()); FreeOSCertHandle(cert_handle); return cert; } // static X509Certificate* X509Certificate::CreateFromPickle(const Pickle& pickle, void** pickle_iter, PickleType type) { OSCertHandle cert_handle = ReadOSCertHandleFromPickle(pickle, pickle_iter); if (!cert_handle) return NULL; OSCertHandles intermediates; size_t num_intermediates = 0; if (type == PICKLETYPE_CERTIFICATE_CHAIN) { if (!pickle.ReadSize(pickle_iter, &num_intermediates)) { FreeOSCertHandle(cert_handle); return NULL; } for (size_t i = 0; i < num_intermediates; ++i) { OSCertHandle intermediate = ReadOSCertHandleFromPickle(pickle, pickle_iter); if (!intermediate) break; intermediates.push_back(intermediate); } } X509Certificate* cert = NULL; if (intermediates.size() == num_intermediates) cert = CreateFromHandle(cert_handle, intermediates); FreeOSCertHandle(cert_handle); for (size_t i = 0; i < intermediates.size(); ++i) FreeOSCertHandle(intermediates[i]); return cert; } // static CertificateList X509Certificate::CreateCertificateListFromBytes( const char* data, int length, int format) { OSCertHandles certificates; // Check to see if it is in a PEM-encoded form. This check is performed // first, as both OS X and NSS will both try to convert if they detect // PEM encoding, except they don't do it consistently between the two. base::StringPiece data_string(data, length); std::vector pem_headers; // To maintain compatibility with NSS/Firefox, CERTIFICATE is a universally // valid PEM block header for any format. pem_headers.push_back(kCertificateHeader); if (format & FORMAT_PKCS7) pem_headers.push_back(kPKCS7Header); PEMTokenizer pem_tok(data_string, pem_headers); while (pem_tok.GetNext()) { std::string decoded(pem_tok.data()); OSCertHandle handle = NULL; if (format & FORMAT_PEM_CERT_SEQUENCE) handle = CreateOSCertHandleFromBytes(decoded.c_str(), decoded.size()); if (handle != NULL) { // Parsed a DER encoded certificate. All PEM blocks that follow must // also be DER encoded certificates wrapped inside of PEM blocks. format = FORMAT_PEM_CERT_SEQUENCE; certificates.push_back(handle); continue; } // If the first block failed to parse as a DER certificate, and // formats other than PEM are acceptable, check to see if the decoded // data is one of the accepted formats. if (format & ~FORMAT_PEM_CERT_SEQUENCE) { for (size_t i = 0; certificates.empty() && i < arraysize(kFormatDecodePriority); ++i) { if (format & kFormatDecodePriority[i]) { certificates = CreateOSCertHandlesFromBytes(decoded.c_str(), decoded.size(), kFormatDecodePriority[i]); } } } // Stop parsing after the first block for any format but a sequence of // PEM-encoded DER certificates. The case of FORMAT_PEM_CERT_SEQUENCE // is handled above, and continues processing until a certificate fails // to parse. break; } // Try each of the formats, in order of parse preference, to see if |data| // contains the binary representation of a Format, if it failed to parse // as a PEM certificate/chain. for (size_t i = 0; certificates.empty() && i < arraysize(kFormatDecodePriority); ++i) { if (format & kFormatDecodePriority[i]) certificates = CreateOSCertHandlesFromBytes(data, length, kFormatDecodePriority[i]); } CertificateList results; // No certificates parsed. if (certificates.empty()) return results; for (OSCertHandles::iterator it = certificates.begin(); it != certificates.end(); ++it) { X509Certificate* result = CreateFromHandle(*it, OSCertHandles()); results.push_back(scoped_refptr(result)); FreeOSCertHandle(*it); } return results; } void X509Certificate::Persist(Pickle* pickle) { DCHECK(cert_handle_); if (!WriteOSCertHandleToPickle(cert_handle_, pickle)) { NOTREACHED(); return; } if (!pickle->WriteSize(intermediate_ca_certs_.size())) { NOTREACHED(); return; } for (size_t i = 0; i < intermediate_ca_certs_.size(); ++i) { if (!WriteOSCertHandleToPickle(intermediate_ca_certs_[i], pickle)) { NOTREACHED(); return; } } } void X509Certificate::GetDNSNames(std::vector* dns_names) const { GetSubjectAltName(dns_names, NULL); if (dns_names->empty()) dns_names->push_back(subject_.common_name); } bool X509Certificate::HasExpired() const { return base::Time::Now() > valid_expiry(); } bool X509Certificate::Equals(const X509Certificate* other) const { return IsSameOSCert(cert_handle_, other->cert_handle_); } bool X509Certificate::HasIntermediateCertificate(OSCertHandle cert) { for (size_t i = 0; i < intermediate_ca_certs_.size(); ++i) { if (IsSameOSCert(cert, intermediate_ca_certs_[i])) return true; } return false; } bool X509Certificate::HasIntermediateCertificates(const OSCertHandles& certs) { for (size_t i = 0; i < certs.size(); ++i) { if (!HasIntermediateCertificate(certs[i])) return false; } return true; } // static bool X509Certificate::VerifyHostname( const std::string& hostname, const std::string& cert_common_name, const std::vector& cert_san_dns_names, const std::vector& cert_san_ip_addrs) { DCHECK(!hostname.empty()); // Perform name verification following http://tools.ietf.org/html/rfc6125. // The terminology used in this method is as per that RFC:- // Reference identifier == the host the local user/agent is intending to // access, i.e. the thing displayed in the URL bar. // Presented identifier(s) == name(s) the server knows itself as, in its cert. // CanonicalizeHost requires surrounding brackets to parse an IPv6 address. const std::string host_or_ip = hostname.find(':') != std::string::npos ? "[" + hostname + "]" : hostname; url_canon::CanonHostInfo host_info; const std::string reference_name = CanonicalizeHost(host_or_ip, &host_info); if (reference_name.empty()) return false; // Allow fallback to Common name matching? const bool common_name_fallback = cert_san_dns_names.empty() && cert_san_ip_addrs.empty(); // Fully handle all cases where |hostname| contains an IP address. if (host_info.IsIPAddress()) { if (common_name_fallback && host_info.family == url_canon::CanonHostInfo::IPV4) { // Fallback to Common name matching. As this is deprecated and only // supported for compatibility refuse it for IPv6 addresses. return reference_name == cert_common_name; } base::StringPiece ip_addr_string( reinterpret_cast(host_info.address), host_info.AddressLength()); return std::find(cert_san_ip_addrs.begin(), cert_san_ip_addrs.end(), ip_addr_string) != cert_san_ip_addrs.end(); } // |reference_domain| is the remainder of |host| after the leading host // component is stripped off, but includes the leading dot e.g. // "www.f.com" -> ".f.com". // If there is no meaningful domain part to |host| (e.g. it contains no dots) // then |reference_domain| will be empty. base::StringPiece reference_host, reference_domain; SplitOnChar(reference_name, '.', &reference_host, &reference_domain); bool allow_wildcards = false; if (!reference_domain.empty()) { DCHECK(reference_domain.starts_with(".")); // We required at least 3 components (i.e. 2 dots) as a basic protection // against too-broad wild-carding. // Also we don't attempt wildcard matching on a purely numerical hostname. allow_wildcards = reference_domain.rfind('.') != 0 && reference_name.find_first_not_of("0123456789.") != std::string::npos; } // Now step through the DNS names doing wild card comparison (if necessary) // on each against the reference name. If subjectAltName is empty, then // fallback to use the common name instead. std::vector common_name_as_vector; const std::vector* presented_names = &cert_san_dns_names; if (common_name_fallback) { // Note: there's a small possibility cert_common_name is an international // domain name in non-standard encoding (e.g. UTF8String or BMPString // instead of A-label). As common name fallback is deprecated we're not // doing anything specific to deal with this. common_name_as_vector.push_back(cert_common_name); presented_names = &common_name_as_vector; } for (std::vector::const_iterator it = presented_names->begin(); it != presented_names->end(); ++it) { // Catch badly corrupt cert names up front. if (it->empty() || it->find('\0') != std::string::npos) { DVLOG(1) << "Bad name in cert: " << *it; continue; } std::string presented_name(StringToLowerASCII(*it)); // Remove trailing dot, if any. if (*presented_name.rbegin() == '.') presented_name.resize(presented_name.length() - 1); // The hostname must be at least as long as the cert name it is matching, // as we require the wildcard (if present) to match at least one character. if (presented_name.length() > reference_name.length()) continue; base::StringPiece presented_host, presented_domain; SplitOnChar(presented_name, '.', &presented_host, &presented_domain); if (presented_domain != reference_domain) continue; base::StringPiece pattern_begin, pattern_end; SplitOnChar(presented_host, '*', &pattern_begin, &pattern_end); if (pattern_end.empty()) { // No '*' in the presented_host if (presented_host == reference_host) return true; continue; } pattern_end.remove_prefix(1); // move past the * if (!allow_wildcards) continue; // * must not match a substring of an IDN A label; just a whole fragment. if (reference_host.starts_with("xn--") && !(pattern_begin.empty() && pattern_end.empty())) continue; if (reference_host.starts_with(pattern_begin) && reference_host.ends_with(pattern_end)) return true; } return false; } int X509Certificate::Verify(const std::string& hostname, int flags, CertVerifyResult* verify_result) const { verify_result->Reset(); if (IsBlacklisted()) { verify_result->cert_status |= CERT_STATUS_REVOKED; return ERR_CERT_REVOKED; } int rv = VerifyInternal(hostname, flags, verify_result); // If needed, do any post-validation here. return rv; } #if !defined(USE_NSS) bool X509Certificate::VerifyNameMatch(const std::string& hostname) const { std::vector dns_names, ip_addrs; GetSubjectAltName(&dns_names, &ip_addrs); return VerifyHostname(hostname, subject_.common_name, dns_names, ip_addrs); } #endif X509Certificate::X509Certificate(OSCertHandle cert_handle, const OSCertHandles& intermediates) : cert_handle_(DupOSCertHandle(cert_handle)) { X509CertificateCache* cache = g_x509_certificate_cache.Pointer(); cache->InsertOrUpdate(&cert_handle_); for (size_t i = 0; i < intermediates.size(); ++i) { // Duplicate the incoming certificate, as the caller retains ownership // of |intermediates|. OSCertHandle intermediate = DupOSCertHandle(intermediates[i]); // Update the cache, which will assume ownership of the duplicated // handle and return a suitable equivalent, potentially from the cache. cache->InsertOrUpdate(&intermediate); intermediate_ca_certs_.push_back(intermediate); } // Platform-specific initialization. Initialize(); } X509Certificate::~X509Certificate() { // We might not be in the cache, but it is safe to remove ourselves anyway. X509CertificateCache* cache = g_x509_certificate_cache.Pointer(); if (cert_handle_) { cache->Remove(cert_handle_); FreeOSCertHandle(cert_handle_); } for (size_t i = 0; i < intermediate_ca_certs_.size(); ++i) { cache->Remove(intermediate_ca_certs_[i]); FreeOSCertHandle(intermediate_ca_certs_[i]); } } bool X509Certificate::IsBlacklisted() const { static const unsigned kNumSerials = 10; static const unsigned kSerialBytes = 16; static const uint8 kSerials[kNumSerials][kSerialBytes] = { // Not a real certificate. For testing only. {0x07,0x7a,0x59,0xbc,0xd5,0x34,0x59,0x60,0x1c,0xa6,0x90,0x72,0x67,0xa6,0xdd,0x1c}, // The next nine certificates all expire on Fri Mar 14 23:59:59 2014. // Some serial numbers actually have a leading 0x00 byte required to // encode a positive integer in DER if the most significant bit is 0. // We omit the leading 0x00 bytes to make all serial numbers 16 bytes. // Subject: CN=mail.google.com // subjectAltName dNSName: mail.google.com, www.mail.google.com {0x04,0x7e,0xcb,0xe9,0xfc,0xa5,0x5f,0x7b,0xd0,0x9e,0xae,0x36,0xe1,0x0c,0xae,0x1e}, // Subject: CN=global trustee // subjectAltName dNSName: global trustee // Note: not a CA certificate. {0xd8,0xf3,0x5f,0x4e,0xb7,0x87,0x2b,0x2d,0xab,0x06,0x92,0xe3,0x15,0x38,0x2f,0xb0}, // Subject: CN=login.live.com // subjectAltName dNSName: login.live.com, www.login.live.com {0xb0,0xb7,0x13,0x3e,0xd0,0x96,0xf9,0xb5,0x6f,0xae,0x91,0xc8,0x74,0xbd,0x3a,0xc0}, // Subject: CN=addons.mozilla.org // subjectAltName dNSName: addons.mozilla.org, www.addons.mozilla.org {0x92,0x39,0xd5,0x34,0x8f,0x40,0xd1,0x69,0x5a,0x74,0x54,0x70,0xe1,0xf2,0x3f,0x43}, // Subject: CN=login.skype.com // subjectAltName dNSName: login.skype.com, www.login.skype.com {0xe9,0x02,0x8b,0x95,0x78,0xe4,0x15,0xdc,0x1a,0x71,0x0a,0x2b,0x88,0x15,0x44,0x47}, // Subject: CN=login.yahoo.com // subjectAltName dNSName: login.yahoo.com, www.login.yahoo.com {0xd7,0x55,0x8f,0xda,0xf5,0xf1,0x10,0x5b,0xb2,0x13,0x28,0x2b,0x70,0x77,0x29,0xa3}, // Subject: CN=www.google.com // subjectAltName dNSName: www.google.com, google.com {0xf5,0xc8,0x6a,0xf3,0x61,0x62,0xf1,0x3a,0x64,0xf5,0x4f,0x6d,0xc9,0x58,0x7c,0x06}, // Subject: CN=login.yahoo.com // subjectAltName dNSName: login.yahoo.com {0x39,0x2a,0x43,0x4f,0x0e,0x07,0xdf,0x1f,0x8a,0xa3,0x05,0xde,0x34,0xe0,0xc2,0x29}, // Subject: CN=login.yahoo.com // subjectAltName dNSName: login.yahoo.com {0x3e,0x75,0xce,0xd4,0x6b,0x69,0x30,0x21,0x21,0x88,0x30,0xae,0x86,0xa8,0x2a,0x71}, }; if (serial_number_.size() == kSerialBytes) { for (unsigned i = 0; i < kNumSerials; i++) { if (memcmp(kSerials[i], serial_number_.data(), kSerialBytes) == 0) { UMA_HISTOGRAM_ENUMERATION("Net.SSLCertBlacklisted", i, kNumSerials); return true; } } } return false; } // static bool X509Certificate::IsSHA1HashInSortedArray(const SHA1Fingerprint& hash, const uint8* array, size_t array_byte_len) { DCHECK_EQ(0u, array_byte_len % base::SHA1_LENGTH); const unsigned arraylen = array_byte_len / base::SHA1_LENGTH; return NULL != bsearch(hash.data, array, arraylen, base::SHA1_LENGTH, CompareSHA1Hashes); } } // namespace net