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// Copyright 2014 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 <vector>
#include "chrome/browser/ssl/ssl_error_classification.h"
#include "base/build_time.h"
#include "base/metrics/field_trial.h"
#include "base/metrics/histogram.h"
#include "base/strings/string_split.h"
#include "base/strings/utf_string_conversions.h"
#include "base/time/time.h"
#include "chrome/browser/browser_process.h"
#include "chrome/browser/chrome_notification_types.h"
#include "chrome/browser/profiles/profile.h"
#include "chrome/browser/ssl/ssl_error_info.h"
#include "content/public/browser/notification_service.h"
#include "content/public/browser/web_contents.h"
#include "net/base/net_util.h"
#include "net/base/registry_controlled_domains/registry_controlled_domain.h"
#include "net/cert/x509_cert_types.h"
#include "net/cert/x509_certificate.h"
#include "url/gurl.h"
#if defined(ENABLE_CAPTIVE_PORTAL_DETECTION)
#include "chrome/browser/captive_portal/captive_portal_service.h"
#include "chrome/browser/captive_portal/captive_portal_service_factory.h"
#endif
#if defined(OS_WIN)
#include "base/win/win_util.h"
#include "base/win/windows_version.h"
#endif
using base::Time;
using base::TimeTicks;
using base::TimeDelta;
namespace {
// Events for UMA. Do not reorder or change!
enum SSLInterstitialCause {
CLOCK_PAST,
CLOCK_FUTURE,
WWW_SUBDOMAIN_MATCH,
SUBDOMAIN_MATCH,
SUBDOMAIN_INVERSE_MATCH,
SUBDOMAIN_OUTSIDE_WILDCARD,
HOST_NAME_NOT_KNOWN_TLD,
LIKELY_MULTI_TENANT_HOSTING,
LOCALHOST,
PRIVATE_URL,
AUTHORITY_ERROR_CAPTIVE_PORTAL,
SELF_SIGNED,
EXPIRED_RECENTLY,
LIKELY_SAME_DOMAIN,
UNUSED_INTERSTITIAL_CAUSE_ENTRY,
};
// Events for UMA. Do not reorder or change!
enum SSLInterstitialCauseCaptivePortal {
CAPTIVE_PORTAL_ALL,
CAPTIVE_PORTAL_DETECTION_ENABLED,
CAPTIVE_PORTAL_DETECTION_ENABLED_OVERRIDABLE,
CAPTIVE_PORTAL_PROBE_COMPLETED,
CAPTIVE_PORTAL_PROBE_COMPLETED_OVERRIDABLE,
CAPTIVE_PORTAL_NO_RESPONSE,
CAPTIVE_PORTAL_NO_RESPONSE_OVERRIDABLE,
CAPTIVE_PORTAL_DETECTED,
CAPTIVE_PORTAL_DETECTED_OVERRIDABLE,
UNUSED_CAPTIVE_PORTAL_EVENT,
};
void RecordSSLInterstitialCause(bool overridable, SSLInterstitialCause event) {
if (overridable) {
UMA_HISTOGRAM_ENUMERATION("interstitial.ssl.cause.overridable", event,
UNUSED_INTERSTITIAL_CAUSE_ENTRY);
} else {
UMA_HISTOGRAM_ENUMERATION("interstitial.ssl.cause.nonoverridable", event,
UNUSED_INTERSTITIAL_CAUSE_ENTRY);
}
}
#if defined(ENABLE_CAPTIVE_PORTAL_DETECTION)
void RecordCaptivePortalEventStats(SSLInterstitialCauseCaptivePortal event) {
UMA_HISTOGRAM_ENUMERATION("interstitial.ssl.captive_portal",
event,
UNUSED_CAPTIVE_PORTAL_EVENT);
}
#endif
int GetLevensteinDistance(const std::string& str1,
const std::string& str2) {
if (str1 == str2)
return 0;
if (str1.size() == 0)
return str2.size();
if (str2.size() == 0)
return str1.size();
std::vector<int> kFirstRow(str2.size() + 1, 0);
std::vector<int> kSecondRow(str2.size() + 1, 0);
for (size_t i = 0; i < kFirstRow.size(); ++i)
kFirstRow[i] = i;
for (size_t i = 0; i < str1.size(); ++i) {
kSecondRow[0] = i + 1;
for (size_t j = 0; j < str2.size(); ++j) {
int cost = str1[i] == str2[j] ? 0 : 1;
kSecondRow[j+1] = std::min(std::min(
kSecondRow[j] + 1, kFirstRow[j + 1] + 1), kFirstRow[j] + cost);
}
for (size_t j = 0; j < kFirstRow.size(); j++)
kFirstRow[j] = kSecondRow[j];
}
return kSecondRow[str2.size()];
}
} // namespace
SSLErrorClassification::SSLErrorClassification(
content::WebContents* web_contents,
const base::Time& current_time,
const GURL& url,
int cert_error,
const net::X509Certificate& cert)
: web_contents_(web_contents),
current_time_(current_time),
request_url_(url),
cert_error_(cert_error),
cert_(cert),
captive_portal_detection_enabled_(false),
captive_portal_probe_completed_(false),
captive_portal_no_response_(false),
captive_portal_detected_(false) {
#if defined(ENABLE_CAPTIVE_PORTAL_DETECTION)
Profile* profile = Profile::FromBrowserContext(
web_contents_->GetBrowserContext());
captive_portal_detection_enabled_ =
CaptivePortalServiceFactory::GetForProfile(profile)->enabled();
registrar_.Add(this,
chrome::NOTIFICATION_CAPTIVE_PORTAL_CHECK_RESULT,
content::Source<Profile>(profile));
#endif
}
SSLErrorClassification::~SSLErrorClassification() { }
void SSLErrorClassification::RecordCaptivePortalUMAStatistics(
bool overridable) const {
#if defined(ENABLE_CAPTIVE_PORTAL_DETECTION)
RecordCaptivePortalEventStats(CAPTIVE_PORTAL_ALL);
if (captive_portal_detection_enabled_)
RecordCaptivePortalEventStats(
overridable ?
CAPTIVE_PORTAL_DETECTION_ENABLED_OVERRIDABLE :
CAPTIVE_PORTAL_DETECTION_ENABLED);
if (captive_portal_probe_completed_)
RecordCaptivePortalEventStats(
overridable ?
CAPTIVE_PORTAL_PROBE_COMPLETED_OVERRIDABLE :
CAPTIVE_PORTAL_PROBE_COMPLETED);
// Log only one of portal detected and no response results.
if (captive_portal_detected_)
RecordCaptivePortalEventStats(
overridable ?
CAPTIVE_PORTAL_DETECTED_OVERRIDABLE :
CAPTIVE_PORTAL_DETECTED);
else if (captive_portal_no_response_)
RecordCaptivePortalEventStats(
overridable ?
CAPTIVE_PORTAL_NO_RESPONSE_OVERRIDABLE :
CAPTIVE_PORTAL_NO_RESPONSE);
#endif
}
void SSLErrorClassification::RecordUMAStatistics(
bool overridable) const {
SSLErrorInfo::ErrorType type =
SSLErrorInfo::NetErrorToErrorType(cert_error_);
UMA_HISTOGRAM_ENUMERATION(
"interstitial.ssl_error_type", type, SSLErrorInfo::END_OF_ENUM);
switch (type) {
case SSLErrorInfo::CERT_DATE_INVALID: {
if (IsUserClockInThePast(base::Time::NowFromSystemTime())) {
RecordSSLInterstitialCause(overridable, CLOCK_PAST);
} else if (IsUserClockInTheFuture(base::Time::NowFromSystemTime())) {
RecordSSLInterstitialCause(overridable, CLOCK_FUTURE);
} else if (cert_.HasExpired() && TimePassedSinceExpiry().InDays() < 28) {
RecordSSLInterstitialCause(overridable, EXPIRED_RECENTLY);
}
break;
}
case SSLErrorInfo::CERT_COMMON_NAME_INVALID: {
std::string host_name = request_url_.host();
if (IsHostNameKnownTLD(host_name)) {
Tokens host_name_tokens = Tokenize(host_name);
if (IsWWWSubDomainMatch())
RecordSSLInterstitialCause(overridable, WWW_SUBDOMAIN_MATCH);
if (IsSubDomainOutsideWildcard(host_name_tokens))
RecordSSLInterstitialCause(overridable, SUBDOMAIN_OUTSIDE_WILDCARD);
std::vector<std::string> dns_names;
cert_.GetDNSNames(&dns_names);
std::vector<Tokens> dns_name_tokens = GetTokenizedDNSNames(dns_names);
if (NameUnderAnyNames(host_name_tokens, dns_name_tokens))
RecordSSLInterstitialCause(overridable, SUBDOMAIN_MATCH);
if (AnyNamesUnderName(dns_name_tokens, host_name_tokens))
RecordSSLInterstitialCause(overridable, SUBDOMAIN_INVERSE_MATCH);
if (IsCertLikelyFromMultiTenantHosting())
RecordSSLInterstitialCause(overridable, LIKELY_MULTI_TENANT_HOSTING);
if (IsCertLikelyFromSameDomain())
RecordSSLInterstitialCause(overridable, LIKELY_SAME_DOMAIN);
} else {
RecordSSLInterstitialCause(overridable, HOST_NAME_NOT_KNOWN_TLD);
}
break;
}
case SSLErrorInfo::CERT_AUTHORITY_INVALID: {
const std::string& hostname = request_url_.HostNoBrackets();
if (net::IsLocalhost(hostname))
RecordSSLInterstitialCause(overridable, LOCALHOST);
if (IsHostnameNonUniqueOrDotless(hostname))
RecordSSLInterstitialCause(overridable, PRIVATE_URL);
if (captive_portal_probe_completed_ && captive_portal_detected_)
RecordSSLInterstitialCause(overridable, AUTHORITY_ERROR_CAPTIVE_PORTAL);
if (net::X509Certificate::IsSelfSigned(cert_.os_cert_handle()))
RecordSSLInterstitialCause(overridable, SELF_SIGNED);
break;
}
default:
break;
}
UMA_HISTOGRAM_ENUMERATION("interstitial.ssl.connection_type",
net::NetworkChangeNotifier::GetConnectionType(),
net::NetworkChangeNotifier::CONNECTION_LAST);
}
base::TimeDelta SSLErrorClassification::TimePassedSinceExpiry() const {
base::TimeDelta delta = current_time_ - cert_.valid_expiry();
return delta;
}
bool SSLErrorClassification::IsUserClockInThePast(const base::Time& time_now) {
#if defined(DONT_EMBED_BUILD_METADATA) && !defined(OFFICIAL_BUILD)
return false;
#else
base::Time build_time = base::GetBuildTime();
if (time_now < build_time - base::TimeDelta::FromDays(2))
return true;
return false;
#endif
}
bool SSLErrorClassification::IsUserClockInTheFuture(
const base::Time& time_now) {
#if defined(DONT_EMBED_BUILD_METADATA) && !defined(OFFICIAL_BUILD)
return false;
#else
base::Time build_time = base::GetBuildTime();
if (time_now > build_time + base::TimeDelta::FromDays(365))
return true;
return false;
#endif
}
bool SSLErrorClassification::MaybeWindowsLacksSHA256Support() {
#if defined(OS_WIN)
return !base::win::MaybeHasSHA256Support();
#else
return false;
#endif
}
bool SSLErrorClassification::IsHostNameKnownTLD(const std::string& host_name) {
size_t tld_length =
net::registry_controlled_domains::GetRegistryLength(
host_name,
net::registry_controlled_domains::EXCLUDE_UNKNOWN_REGISTRIES,
net::registry_controlled_domains::INCLUDE_PRIVATE_REGISTRIES);
if (tld_length == 0 || tld_length == std::string::npos)
return false;
return true;
}
std::vector<SSLErrorClassification::Tokens> SSLErrorClassification::
GetTokenizedDNSNames(const std::vector<std::string>& dns_names) {
std::vector<std::vector<std::string>> dns_name_tokens;
for (size_t i = 0; i < dns_names.size(); ++i) {
std::vector<std::string> dns_name_token_single;
if (dns_names[i].empty() || dns_names[i].find('\0') != std::string::npos
|| !(IsHostNameKnownTLD(dns_names[i]))) {
dns_name_token_single.push_back(std::string());
} else {
dns_name_token_single = Tokenize(dns_names[i]);
}
dns_name_tokens.push_back(dns_name_token_single);
}
return dns_name_tokens;
}
size_t SSLErrorClassification::FindSubDomainDifference(
const Tokens& potential_subdomain, const Tokens& parent) const {
// A check to ensure that the number of tokens in the tokenized_parent is
// less than the tokenized_potential_subdomain.
if (parent.size() >= potential_subdomain.size())
return 0;
size_t tokens_match = 0;
size_t diff_size = potential_subdomain.size() - parent.size();
for (size_t i = 0; i < parent.size(); ++i) {
if (parent[i] == potential_subdomain[i + diff_size])
tokens_match++;
}
if (tokens_match == parent.size())
return diff_size;
return 0;
}
SSLErrorClassification::Tokens SSLErrorClassification::
Tokenize(const std::string& name) {
return base::SplitString(
name, ".", base::KEEP_WHITESPACE, base::SPLIT_WANT_ALL);
}
// We accept the inverse case for www for historical reasons.
bool SSLErrorClassification::IsWWWSubDomainMatch() const {
std::string host_name = request_url_.host();
if (IsHostNameKnownTLD(host_name)) {
std::vector<std::string> dns_names;
cert_.GetDNSNames(&dns_names);
bool result = false;
// Need to account for all possible domains given in the SSL certificate.
for (size_t i = 0; i < dns_names.size(); ++i) {
if (dns_names[i].empty() || dns_names[i].find('\0') != std::string::npos
|| dns_names[i].length() == host_name.length()
|| !(IsHostNameKnownTLD(dns_names[i]))) {
result = result || false;
} else if (dns_names[i].length() > host_name.length()) {
result = result ||
net::StripWWW(base::ASCIIToUTF16(dns_names[i])) ==
base::ASCIIToUTF16(host_name);
} else {
result = result ||
net::StripWWW(base::ASCIIToUTF16(host_name)) ==
base::ASCIIToUTF16(dns_names[i]);
}
}
return result;
}
return false;
}
bool SSLErrorClassification::NameUnderAnyNames(
const Tokens& child,
const std::vector<Tokens>& potential_parents) const {
bool result = false;
// Need to account for all the possible domains given in the SSL certificate.
for (size_t i = 0; i < potential_parents.size(); ++i) {
if (potential_parents[i].empty() ||
potential_parents[i].size() >= child.size()) {
result = result || false;
} else {
size_t domain_diff = FindSubDomainDifference(child,
potential_parents[i]);
if (domain_diff == 1 && child[0] != "www")
result = result || true;
}
}
return result;
}
bool SSLErrorClassification::AnyNamesUnderName(
const std::vector<Tokens>& potential_children,
const Tokens& parent) const {
bool result = false;
// Need to account for all the possible domains given in the SSL certificate.
for (size_t i = 0; i < potential_children.size(); ++i) {
if (potential_children[i].empty() ||
potential_children[i].size() <= parent.size()) {
result = result || false;
} else {
size_t domain_diff = FindSubDomainDifference(potential_children[i],
parent);
if (domain_diff == 1 && potential_children[i][0] != "www")
result = result || true;
}
}
return result;
}
bool SSLErrorClassification::IsSubDomainOutsideWildcard(
const Tokens& host_name_tokens) const {
std::string host_name = request_url_.host();
std::vector<std::string> dns_names;
cert_.GetDNSNames(&dns_names);
bool result = false;
// This method requires that the host name be longer than the dns name on
// the certificate.
for (size_t i = 0; i < dns_names.size(); ++i) {
const std::string& name = dns_names[i];
if (name.length() < 2 || name.length() >= host_name.length() ||
name.find('\0') != std::string::npos ||
!IsHostNameKnownTLD(name)
|| name[0] != '*' || name[1] != '.') {
continue;
}
// Move past the "*.".
std::string extracted_dns_name = name.substr(2);
if (FindSubDomainDifference(
host_name_tokens, Tokenize(extracted_dns_name)) == 2) {
return true;
}
}
return result;
}
bool SSLErrorClassification::IsCertLikelyFromMultiTenantHosting() const {
std::string host_name = request_url_.host();
std::vector<std::string> dns_names;
std::vector<std::string> dns_names_domain;
cert_.GetDNSNames(&dns_names);
size_t dns_names_size = dns_names.size();
// If there is only 1 DNS name then it is definitely not a shared certificate.
if (dns_names_size == 0 || dns_names_size == 1)
return false;
// Check to see if all the domains in the SAN field in the SSL certificate are
// the same or not.
for (size_t i = 0; i < dns_names_size; ++i) {
dns_names_domain.push_back(
net::registry_controlled_domains::
GetDomainAndRegistry(
dns_names[i],
net::registry_controlled_domains::INCLUDE_PRIVATE_REGISTRIES));
}
for (size_t i = 1; i < dns_names_domain.size(); ++i) {
if (dns_names_domain[i] != dns_names_domain[0])
return false;
}
// If the number of DNS names is more than 5 then assume that it is a shared
// certificate.
static const int kDistinctNameThreshold = 5;
if (dns_names_size > kDistinctNameThreshold)
return true;
// Heuristic - The edit distance between all the strings should be at least 5
// for it to be counted as a shared SSLCertificate. If even one pair of
// strings edit distance is below 5 then the certificate is no longer
// considered as a shared certificate. Include the host name in the URL also
// while comparing.
dns_names.push_back(host_name);
static const int kMinimumEditDsitance = 5;
for (size_t i = 0; i < dns_names_size; ++i) {
for (size_t j = i + 1; j < dns_names_size; ++j) {
int edit_distance = GetLevensteinDistance(dns_names[i], dns_names[j]);
if (edit_distance < kMinimumEditDsitance)
return false;
}
}
return true;
}
bool SSLErrorClassification::IsCertLikelyFromSameDomain() const {
std::string host_name = request_url_.host();
std::vector<std::string> dns_names;
cert_.GetDNSNames(&dns_names);
dns_names.push_back(host_name);
std::vector<std::string> dns_names_domain;
for (const std::string& dns_name : dns_names) {
dns_names_domain.push_back(
net::registry_controlled_domains::GetDomainAndRegistry(
dns_name,
net::registry_controlled_domains::INCLUDE_PRIVATE_REGISTRIES));
}
DCHECK(!dns_names_domain.empty());
const std::string& host_name_domain = dns_names_domain.back();
// Last element is the original domain. So, excluding it.
return std::find(dns_names_domain.begin(), dns_names_domain.end() - 1,
host_name_domain) != dns_names_domain.end() - 1;
}
// static
bool SSLErrorClassification::IsHostnameNonUniqueOrDotless(
const std::string& hostname) {
return net::IsHostnameNonUnique(hostname) ||
hostname.find('.') == std::string::npos;
}
void SSLErrorClassification::Observe(
int type,
const content::NotificationSource& source,
const content::NotificationDetails& details) {
#if defined(ENABLE_CAPTIVE_PORTAL_DETECTION)
// When detection is disabled, captive portal service always sends
// RESULT_INTERNET_CONNECTED. Ignore any probe results in that case.
if (!captive_portal_detection_enabled_)
return;
if (type == chrome::NOTIFICATION_CAPTIVE_PORTAL_CHECK_RESULT) {
captive_portal_probe_completed_ = true;
CaptivePortalService::Results* results =
content::Details<CaptivePortalService::Results>(details).ptr();
// If a captive portal was detected at any point when the interstitial was
// displayed, assume that the interstitial was caused by a captive portal.
// Example scenario:
// 1- Interstitial displayed and captive portal detected, setting the flag.
// 2- Captive portal detection automatically opens portal login page.
// 3- User logs in on the portal login page.
// A notification will be received here for RESULT_INTERNET_CONNECTED. Make
// sure we don't clear the captive protal flag, since the interstitial was
// potentially caused by the captive portal.
captive_portal_detected_ = captive_portal_detected_ ||
(results->result == captive_portal::RESULT_BEHIND_CAPTIVE_PORTAL);
// Also keep track of non-HTTP portals and error cases.
captive_portal_no_response_ = captive_portal_no_response_ ||
(results->result == captive_portal::RESULT_NO_RESPONSE);
}
#endif
}
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