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foundationdb/flow/TLSPolicy.cpp

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/*
* TLSPolicy.cpp
*
* This source file is part of the FoundationDB open source project
*
* Copyright 2013-2020 Apple Inc. and the FoundationDB project authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "flow/TLSPolicy.h"
TLSPolicy::~TLSPolicy() {}
#ifndef TLS_DISABLED
#include <algorithm>
#include <cstring>
#include <exception>
#include <map>
#include <set>
#include <openssl/objects.h>
#include <openssl/bio.h>
#include <openssl/err.h>
#include <openssl/pem.h>
#include <openssl/x509.h>
#include <openssl/x509v3.h>
#include <openssl/x509_vfy.h>
#include <stdint.h>
#include <string>
#include <sstream>
#include <utility>
#include "flow/FastRef.h"
#include "flow/Trace.h"
std::string TLSPolicy::ErrorString(boost::system::error_code e) {
char* str = ERR_error_string(e.value(), NULL);
return std::string(str);
}
// To force typeinfo to only be emitted once.
std::string TLSPolicy::toString() const {
std::stringstream ss;
ss << "TLSPolicy{ Rules=[";
for (const auto &r : rules) {
ss << " " << r.toString() << ",";
}
ss << " ] }";
return ss.str();
}
std::string TLSPolicy::Rule::toString() const {
std::stringstream ss;
ss << "Rule{ verify_cert=" << verify_cert
<< ", verify_time=" << verify_time;
ss << ", Subject=[";
for (const auto& s : subject_criteria) {
ss << " { NID=" << s.first << ", Criteria=" << s.second.criteria << "},";
}
ss << " ], Issuer=[";
for (const auto& s : issuer_criteria) {
ss << " { NID=" << s.first << ", Criteria=" << s.second.criteria << "},";
}
ss << " ], Root=[";
for (const auto& s : root_criteria) {
ss << " { NID=" << s.first << ", Criteria=" << s.second.criteria << "},";
}
ss << " ] }";
return ss.str();
}
static int hexValue(char c) {
static char const digits[] = "0123456789ABCDEF";
if (c >= 'a' && c <= 'f')
c -= ('a' - 'A');
int value = std::find(digits, digits + 16, c) - digits;
if (value >= 16) {
throw std::runtime_error("hexValue");
}
return value;
}
// Does not handle "raw" form (e.g. #28C4D1), only escaped text
static std::string de4514(std::string const& input, int start, int& out_end) {
std::string output;
if(input[start] == '#' || input[start] == ' ') {
out_end = start;
return output;
}
int space_count = 0;
for(int p = start; p < input.size();) {
switch(input[p]) {
case '\\': // Handle escaped sequence
// Backslash escaping nothing!
if(p == input.size() - 1) {
out_end = p;
goto FIN;
}
switch(input[p+1]) {
case ' ':
case '"':
case '#':
case '+':
case ',':
case ';':
case '<':
case '=':
case '>':
case '|':
case '\\':
output += input[p+1];
p += 2;
space_count = 0;
continue;
default:
// Backslash escaping pair of hex digits requires two characters
if(p == input.size() - 2) {
out_end = p;
goto FIN;
}
try {
output += hexValue(input[p+1]) * 16 + hexValue(input[p+2]);
p += 3;
space_count = 0;
continue;
} catch( ... ) {
out_end = p;
goto FIN;
}
}
case '"':
case '+':
case ',':
case ';':
case '<':
case '>':
case 0:
// All of these must have been escaped
out_end = p;
goto FIN;
default:
// Character is what it is
output += input[p];
if(input[p] == ' ')
space_count++;
else
space_count = 0;
p++;
}
}
out_end = input.size();
FIN:
out_end -= space_count;
output.resize(output.size() - space_count);
return output;
}
static std::pair<std::string, std::string> splitPair(std::string const& input, char c) {
int p = input.find_first_of(c);
if(p == input.npos) {
throw std::runtime_error("splitPair");
}
return std::make_pair(input.substr(0, p), input.substr(p+1, input.size()));
}
static NID abbrevToNID(std::string const& sn) {
NID nid = NID_undef;
if (sn == "C" || sn == "CN" || sn == "L" || sn == "ST" || sn == "O" || sn == "OU" || sn == "UID" || sn == "DC" || sn == "subjectAltName")
nid = OBJ_sn2nid(sn.c_str());
if (nid == NID_undef)
throw std::runtime_error("abbrevToNID");
return nid;
}
static X509Location locationForNID(NID nid) {
const char* name = OBJ_nid2ln(nid);
if (name == NULL) {
throw std::runtime_error("locationForNID");
}
if (strncmp(name, "X509v3", 6) == 0) {
return X509Location::EXTENSION;
} else {
// It probably isn't true that all other NIDs live in the NAME, but it is for now...
return X509Location::NAME;
}
}
bool TLSPolicy::set_verify_peers(std::vector<std::string> verify_peers) {
for (int i = 0; i < verify_peers.size(); i++) {
try {
std::string& verifyString = verify_peers[i];
int start = 0;
while(start < verifyString.size()) {
int split = verifyString.find('|', start);
if(split == std::string::npos) {
break;
}
if(split == start || verifyString[split-1] != '\\') {
rules.emplace_back(verifyString.substr(start,split-start));
start = split+1;
}
}
rules.emplace_back(verifyString.substr(start));
} catch ( const std::runtime_error& e ) {
rules.clear();
std::string& verifyString = verify_peers[i];
TraceEvent(SevError, "FDBLibTLSVerifyPeersParseError").detail("Config", verifyString);
return false;
}
}
return true;
}
TLSPolicy::Rule::Rule(std::string input) {
int s = 0;
while (s < input.size()) {
int eq = input.find('=', s);
if (eq == input.npos)
throw std::runtime_error("parse_verify");
MatchType mt = MatchType::EXACT;
if (input[eq-1] == '>') mt = MatchType::PREFIX;
if (input[eq-1] == '<') mt = MatchType::SUFFIX;
std::string term = input.substr(s, eq - s - (mt == MatchType::EXACT ? 0 : 1));
if (term.find("Check.") == 0) {
if (eq + 2 > input.size())
throw std::runtime_error("parse_verify");
if (eq + 2 != input.size() && input[eq + 2] != ',')
throw std::runtime_error("parse_verify");
if (mt != MatchType::EXACT)
throw std::runtime_error("parse_verify: cannot prefix match Check");
bool* flag;
if (term == "Check.Valid")
flag = &verify_cert;
else if (term == "Check.Unexpired")
flag = &verify_time;
else
throw std::runtime_error("parse_verify");
if (input[eq + 1] == '0')
*flag = false;
else if (input[eq + 1] == '1')
*flag = true;
else
throw std::runtime_error("parse_verify");
s = eq + 3;
} else {
std::map< int, Criteria >* criteria = &subject_criteria;
if (term.find('.') != term.npos) {
auto scoped = splitPair(term, '.');
if (scoped.first == "S" || scoped.first == "Subject")
criteria = &subject_criteria;
else if (scoped.first == "I" || scoped.first == "Issuer")
criteria = &issuer_criteria;
else if (scoped.first == "R" || scoped.first == "Root")
criteria = &root_criteria;
else
throw std::runtime_error("parse_verify");
term = scoped.second;
}
int remain;
auto unesc = de4514(input, eq + 1, remain);
if (remain == eq + 1)
throw std::runtime_error("parse_verify");
NID termNID = abbrevToNID(term);
const X509Location loc = locationForNID(termNID);
criteria->insert(std::make_pair(termNID, Criteria(unesc, mt, loc)));
if (remain != input.size() && input[remain] != ',')
throw std::runtime_error("parse_verify");
s = remain + 1;
}
}
}
bool match_criteria_entry(const std::string& criteria, ASN1_STRING* entry, MatchType mt) {
bool rc = false;
ASN1_STRING* asn_criteria = NULL;
unsigned char* criteria_utf8 = NULL;
int criteria_utf8_len = 0;
unsigned char* entry_utf8 = NULL;
int entry_utf8_len = 0;
if ((asn_criteria = ASN1_IA5STRING_new()) == NULL)
goto err;
if (ASN1_STRING_set(asn_criteria, criteria.c_str(), criteria.size()) != 1)
goto err;
if ((criteria_utf8_len = ASN1_STRING_to_UTF8(&criteria_utf8, asn_criteria)) < 1)
goto err;
if ((entry_utf8_len = ASN1_STRING_to_UTF8(&entry_utf8, entry)) < 1)
goto err;
if (mt == MatchType::EXACT) {
if (criteria_utf8_len == entry_utf8_len &&
memcmp(criteria_utf8, entry_utf8, criteria_utf8_len) == 0)
rc = true;
} else if (mt == MatchType::PREFIX) {
if (criteria_utf8_len <= entry_utf8_len &&
memcmp(criteria_utf8, entry_utf8, criteria_utf8_len) == 0)
rc = true;
} else if (mt == MatchType::SUFFIX) {
if (criteria_utf8_len <= entry_utf8_len &&
memcmp(criteria_utf8, entry_utf8 + (entry_utf8_len - criteria_utf8_len), criteria_utf8_len) == 0)
rc = true;
}
err:
ASN1_STRING_free(asn_criteria);
free(criteria_utf8);
free(entry_utf8);
return rc;
}
bool match_name_criteria(X509_NAME *name, NID nid, const std::string& criteria, MatchType mt) {
X509_NAME_ENTRY *name_entry;
int idx;
// If name does not exist, or has multiple of this RDN, refuse to proceed.
if ((idx = X509_NAME_get_index_by_NID(name, nid, -1)) < 0)
return false;
if (X509_NAME_get_index_by_NID(name, nid, idx) != -1)
return false;
if ((name_entry = X509_NAME_get_entry(name, idx)) == NULL)
return false;
return match_criteria_entry(criteria, X509_NAME_ENTRY_get_data(name_entry), mt);
}
bool match_extension_criteria(X509 *cert, NID nid, const std::string& value, MatchType mt) {
if (nid != NID_subject_alt_name && nid != NID_issuer_alt_name) {
// I have no idea how other extensions work.
return false;
}
auto pos = value.find(':');
if (pos == value.npos) {
return false;
}
std::string value_gen = value.substr(0, pos);
std::string value_val = value.substr(pos+1, value.npos);
STACK_OF(GENERAL_NAME)* sans = reinterpret_cast<STACK_OF(GENERAL_NAME)*>(X509_get_ext_d2i(cert, nid, NULL, NULL));
if (sans == NULL) {
return false;
}
int num_sans = sk_GENERAL_NAME_num( sans );
bool rc = false;
for( int i = 0; i < num_sans && !rc; ++i ) {
GENERAL_NAME* altname = sk_GENERAL_NAME_value( sans, i );
std::string matchable;
switch (altname->type) {
case GEN_OTHERNAME:
break;
case GEN_EMAIL:
if (value_gen == "EMAIL" &&
match_criteria_entry( value_val, altname->d.rfc822Name, mt)) {
rc = true;
break;
}
case GEN_DNS:
if (value_gen == "DNS" &&
match_criteria_entry( value_val, altname->d.dNSName, mt )) {
rc = true;
break;
}
case GEN_X400:
case GEN_DIRNAME:
case GEN_EDIPARTY:
break;
case GEN_URI:
if (value_gen == "URI" &&
match_criteria_entry( value_val, altname->d.uniformResourceIdentifier, mt )) {
rc = true;
break;
}
case GEN_IPADD:
if (value_gen == "IP" &&
match_criteria_entry( value_val, altname->d.iPAddress, mt )) {
rc = true;
break;
}
case GEN_RID:
break;
}
}
sk_GENERAL_NAME_pop_free(sans, GENERAL_NAME_free);
return rc;
}
bool match_criteria(X509* cert, X509_NAME* subject, NID nid, const std::string& criteria, MatchType mt, X509Location loc) {
switch(loc) {
case X509Location::NAME: {
return match_name_criteria(subject, nid, criteria, mt);
}
case X509Location::EXTENSION: {
return match_extension_criteria(cert, nid, criteria, mt);
}
}
// Should never be reachable.
return false;
}
std::tuple<bool,std::string> check_verify(const TLSPolicy::Rule* verify, X509_STORE_CTX* store_ctx, bool is_client) {
X509_NAME *subject, *issuer;
bool rc = false;
X509* cert = NULL;
// if returning false, give a reason string
std::string reason = "";
// Check subject criteria.
cert = sk_X509_value(X509_STORE_CTX_get0_chain(store_ctx), 0);
if ((subject = X509_get_subject_name(cert)) == NULL) {
reason = "Cert subject error";
goto err;
}
for (auto &pair: verify->subject_criteria) {
if (!match_criteria(cert, subject, pair.first, pair.second.criteria, pair.second.match_type, pair.second.location)) {
reason = "Cert subject match failure";
goto err;
}
}
// Check issuer criteria.
if ((issuer = X509_get_issuer_name(cert)) == NULL) {
reason = "Cert issuer error";
goto err;
}
for (auto &pair: verify->issuer_criteria) {
if (!match_criteria(cert, issuer, pair.first, pair.second.criteria, pair.second.match_type, pair.second.location)) {
reason = "Cert issuer match failure";
goto err;
}
}
// Check root criteria - this is the subject of the final certificate in the stack.
cert = sk_X509_value(X509_STORE_CTX_get0_chain(store_ctx), sk_X509_num(X509_STORE_CTX_get0_chain(store_ctx)) - 1);
if ((subject = X509_get_subject_name(cert)) == NULL) {
reason = "Root subject error";
goto err;
}
for (auto &pair: verify->root_criteria) {
if (!match_criteria(cert, subject, pair.first, pair.second.criteria, pair.second.match_type, pair.second.location)) {
reason = "Root subject match failure";
goto err;
}
}
// If we got this far, everything checked out...
rc = true;
err:
return std::make_tuple(rc, reason);
}
bool TLSPolicy::verify_peer(bool preverified, X509_STORE_CTX* store_ctx) {
bool rc = false;
std::set<std::string> verify_failure_reasons;
bool verify_success;
std::string verify_failure_reason;
// If certificate verification is disabled, there's nothing more to do.
if (std::any_of(rules.begin(), rules.end(), [](const Rule& r){ return !r.verify_cert; })) {
return true;
}
if(!preverified) {
TraceEvent("TLSPolicyFailure").suppressFor(1.0).detail("Reason", "preverification failed").detail("VerifyError", X509_verify_cert_error_string(X509_STORE_CTX_get_error(store_ctx)));
return false;
}
if(!rules.size()) {
return true;
}
// Any matching rule is sufficient.
for (auto &verify_rule: rules) {
std::tie(verify_success, verify_failure_reason) = check_verify(&verify_rule, store_ctx, is_client);
if (verify_success) {
rc = true;
break;
} else {
if (verify_failure_reason.length() > 0)
verify_failure_reasons.insert(verify_failure_reason);
}
}
if (!rc) {
// log the various failure reasons
for (std::string reason : verify_failure_reasons) {
TraceEvent("TLSPolicyFailure").suppressFor(1.0).detail("Reason", reason);
}
}
return rc;
}
#endif
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