Final? bug fixes to CRL addition.
[shibboleth/cpp-xmltooling.git] / xmltooling / security / impl / AbstractPKIXTrustEngine.cpp
index fa2605f..5f42ad2 100644 (file)
 #include "security/CredentialResolver.h"
 #include "security/KeyInfoResolver.h"
 #include "security/OpenSSLCryptoX509CRL.h"
+#include "security/SecurityHelper.h"
 #include "security/X509Credential.h"
 #include "signature/SignatureValidator.h"
 #include "util/NDC.h"
+#include "util/PathResolver.h"
 
+#include <fstream>
 #include <openssl/x509_vfy.h>
 #include <openssl/x509v3.h>
 #include <xercesc/util/XMLUniDefs.hpp>
@@ -53,10 +56,204 @@ namespace {
         return ok;
     }
 
+    static string XMLTOOL_DLLLOCAL X509_NAME_to_string(X509_NAME* n)
+    {
+        string s;
+        BIO* b = BIO_new(BIO_s_mem());
+        X509_NAME_print_ex(b,n,0,XN_FLAG_RFC2253);
+        BIO_flush(b);
+        BUF_MEM* bptr=nullptr;
+        BIO_get_mem_ptr(b, &bptr);
+        if (bptr && bptr->length > 0) {
+            s.append(bptr->data, bptr->length);
+        }
+        BIO_free(b);
+        return s;
+    }
+
+    static time_t XMLTOOL_DLLLOCAL getCRLTime(const ASN1_TIME *a)
+    {
+        struct tm t;
+        memset(&t, 0, sizeof(t));
+        // RFC 5280, sections 5.1.2.4 and 5.1.2.5 require thisUpdate and nextUpdate
+        // to be encoded as UTCTime until 2049, and RFC 5280 section 4.1.2.5.1
+        // further restricts the format to "YYMMDDHHMMSSZ" ("even where the number
+        // of seconds is zero").
+        // As long as OpenSSL doesn't provide any API to convert ASN1_TIME values
+        // time_t, we therefore have to parse it ourselves, unfortunately.
+        if (sscanf((const char*)a->data, "%2d%2d%2d%2d%2d%2dZ",
+            &t.tm_year, &t.tm_mon, &t.tm_mday,
+            &t.tm_hour, &t.tm_min, &t.tm_sec) == 6) {
+            if (t.tm_year <= 50) {
+                // RFC 5280, section 4.1.2.5.1
+                t.tm_year += 100;
+            }
+            t.tm_mon--;
+#if defined(HAVE_TIMEGM)
+            return timegm(&t);
+#else
+            // Windows, and hopefully most others...?
+            return mktime(&t) - timezone;
+#endif
+        }
+        return (time_t)-1;
+    }
+
+    static bool XMLTOOL_DLLLOCAL isFreshCRL(XSECCryptoX509CRL *c, Category* log=nullptr)
+    {
+        // eventually, these should be made configurable
+        #define MIN_SECS_REMAINING 86400
+        #define MIN_PERCENT_REMAINING 10
+        if (c) {
+            const X509_CRL* crl = static_cast<OpenSSLCryptoX509CRL*>(c)->getOpenSSLX509CRL();
+            time_t thisUpdate = getCRLTime(X509_CRL_get_lastUpdate(crl));
+            time_t nextUpdate = getCRLTime(X509_CRL_get_nextUpdate(crl));
+            time_t now = time(nullptr);
+
+            if (thisUpdate < 0 || nextUpdate < 0) {
+                // we failed to parse at least one of the fields (they were not encoded
+                // as required by RFC 5280, actually)
+                time_t exp = now + MIN_SECS_REMAINING;
+                if (log) {
+                    log->warn("isFreshCRL (issuer '%s'): improperly encoded thisUpdate or nextUpdate field - falling back to simple time comparison",
+                              (X509_NAME_to_string(X509_CRL_get_issuer(crl))).c_str());
+                }
+                return (X509_cmp_time(X509_CRL_get_nextUpdate(crl), &exp) > 0) ? true : false;
+            }
+            else {
+                if (log && log->isDebugEnabled()) {
+                    log->debug("isFreshCRL (issuer '%s'): %.0f seconds until nextUpdate (%3.2f%% elapsed since thisUpdate)",
+                              (X509_NAME_to_string(X509_CRL_get_issuer(crl))).c_str(),
+                              difftime(nextUpdate, now), (difftime(now, thisUpdate) * 100) / difftime(nextUpdate, thisUpdate));
+                }
+
+                // consider it recent enough if there are at least MIN_SECS_REMAINING
+                // to the nextUpdate, and at least MIN_PERCENT_REMAINING of its
+                // overall "validity" are remaining to the nextUpdate
+                return (now + MIN_SECS_REMAINING < nextUpdate) &&
+                        ((difftime(nextUpdate, now) * 100) / difftime(nextUpdate, thisUpdate) > MIN_PERCENT_REMAINING);
+            }
+        }
+        return false;
+    }
+
+    static XSECCryptoX509CRL* XMLTOOL_DLLLOCAL getRemoteCRLs(const char* cdpuri, Category& log) {
+        // This is a temporary CRL cache implementation to avoid breaking binary compatibility
+        // for the library. Caching can't rely on any member objects within the TrustEngine,
+        // including locks, so we're using the global library lock for the time being.
+        // All other state is kept in the file system.
+
+        // minimum number of seconds between re-attempting a download from one particular CRLDP
+        #define MIN_RETRY_WAIT 60
+
+        // The filenames for the CRL cache are based on a hash of the CRL location.
+        string cdpfile = SecurityHelper::doHash("SHA1", cdpuri, strlen(cdpuri)) + ".crl";
+        XMLToolingConfig::getConfig().getPathResolver()->resolve(cdpfile, PathResolver::XMLTOOLING_RUN_FILE);
+        string cdpstaging = cdpfile + ".tmp";
+        string tsfile = cdpfile + ".ts";
+
+        time_t now = time(nullptr);
+        vector<XSECCryptoX509CRL*> crls;
+
+        try {
+            // While holding the lock, check for a cached copy of the CRL, and remove "expired" ones.
+            Locker glock(&XMLToolingConfig::getConfig());
+#ifdef WIN32
+            struct _stat stat_buf;
+            if (_stat(cdpfile.c_str(), &stat_buf) == 0) {
+#else
+            struct stat stat_buf;
+            if (stat(cdpfile.c_str(), &stat_buf) == 0) {
+#endif
+                SecurityHelper::loadCRLsFromFile(crls, cdpfile.c_str());
+                if (crls.empty() || crls.front()->getProviderName() != DSIGConstants::s_unicodeStrPROVOpenSSL ||
+                    X509_cmp_time(X509_CRL_get_nextUpdate(static_cast<OpenSSLCryptoX509CRL*>(crls.front())->getOpenSSLX509CRL()), &now) < 0) {
+                    for_each(crls.begin(), crls.end(), xmltooling::cleanup<XSECCryptoX509CRL>());
+                    crls.clear();
+                    remove(cdpfile.c_str());    // may as well delete the local copy
+                    remove(tsfile.c_str());
+                    log.info("deleting cached CRL from %s with nextUpdate field in the past", cdpuri);
+                }
+            }
+        }
+        catch (exception& ex) {
+            log.error("exception loading cached copy of CRL from %s: %s", cdpuri, ex.what());
+        }
+
+        if (crls.empty() || !isFreshCRL(crls.front(), &log)) {
+            bool updateTimestamp = true;
+            try {
+                // If we get here, the cached copy didn't exist yet, or it's time to refresh.
+                // To limit the rate of unsuccessful attempts when a CRLDP is unreachable,
+                // we remember the timestamp of the last attempt (both successful/unsuccessful).
+                // We store this in the file system because of the binary compatibility issue.
+                time_t ts = 0;
+                try {
+                    Locker glock(&XMLToolingConfig::getConfig());
+                    ifstream tssrc(tsfile.c_str());
+                    if (tssrc)
+                        tssrc >> ts;
+                }
+                catch (exception&) {
+                    ts = 0;
+                }
+
+                if (difftime(now, ts) > MIN_RETRY_WAIT) {
+                    SOAPTransport::Address addr("AbstractPKIXTrustEngine", cdpuri, cdpuri);
+                    string scheme(addr.m_endpoint, strchr(addr.m_endpoint,':') - addr.m_endpoint);
+                    auto_ptr<SOAPTransport> soap(XMLToolingConfig::getConfig().SOAPTransportManager.newPlugin(scheme.c_str(), addr));
+                    soap->send();
+                    istream& msg = soap->receive();
+                    Locker glock(&XMLToolingConfig::getConfig());
+                    ofstream out(cdpstaging.c_str(), fstream::trunc|fstream::binary);
+                    out << msg.rdbuf();
+                    out.close();
+                    SecurityHelper::loadCRLsFromFile(crls, cdpstaging.c_str());
+                    if (crls.empty() || crls.front()->getProviderName() != DSIGConstants::s_unicodeStrPROVOpenSSL ||
+                        X509_cmp_time(X509_CRL_get_nextUpdate(static_cast<OpenSSLCryptoX509CRL*>(crls.front())->getOpenSSLX509CRL()), &now) < 0) {
+                        // The "new" CRL wasn't usable, so get rid of it.
+                        for_each(crls.begin(), crls.end(), xmltooling::cleanup<XSECCryptoX509CRL>());
+                        crls.clear();
+                        remove(cdpstaging.c_str());
+                        log.error("ignoring CRL retrieved from %s with nextUpdate field in the past", cdpuri);
+                    }
+                    else {
+                        // "Commit" the new CRL. Note that we might add a CRL which doesn't pass
+                        // isFreshCRL, but that's preferrable over adding none at all.
+                        log.info("CRL refreshed from %s", cdpuri);
+                        remove(cdpfile.c_str());
+                        if (rename(cdpstaging.c_str(), cdpfile.c_str()) != 0)
+                            log.error("unable to rename CRL staging file");
+                    }
+                }
+                else {
+                    updateTimestamp = false;    // don't update if we're within the backoff window
+                }
+            }
+            catch (exception& ex) {
+                log.error("exception downloading/caching CRL from %s: %s", cdpuri, ex.what());
+            }
+
+            if (updateTimestamp) {
+                // update the timestamp file
+                Locker glock(&XMLToolingConfig::getConfig());
+                ofstream tssink(tsfile.c_str(), fstream::trunc);
+                tssink << now;
+                tssink.close();
+            }
+        }
+
+        if (crls.empty())
+            return nullptr;
+        for_each(crls.begin() + 1, crls.end(), xmltooling::cleanup<XSECCryptoX509CRL>());
+        return crls.front();
+    }
+
     static bool XMLTOOL_DLLLOCAL validate(
         X509* EE,
         STACK_OF(X509)* untrusted,
         AbstractPKIXTrustEngine::PKIXValidationInfoIterator* pkixInfo,
+               bool useCRL,
         bool fullCRLChain,
         const vector<XSECCryptoX509CRL*>* inlineCRLs=nullptr
         )
@@ -73,68 +270,38 @@ namespace {
             return false;
         }
     
-        STACK_OF(X509)* CAstack = sk_X509_new_null();
-        
         // This contains the state of the validate operation.
         int count=0;
         X509_STORE_CTX ctx;
-        
-        const vector<XSECCryptoX509*>& CAcerts = pkixInfo->getTrustAnchors();
-        for (vector<XSECCryptoX509*>::const_iterator i=CAcerts.begin(); i!=CAcerts.end(); ++i) {
-            if ((*i)->getProviderName()==DSIGConstants::s_unicodeStrPROVOpenSSL) {
-                sk_X509_push(CAstack,static_cast<OpenSSLCryptoX509*>(*i)->getOpenSSLX509());
-                ++count;
-            }
-        }
-
-        log.debug("supplied (%d) CA certificate(s)", count);
-
-#if (OPENSSL_VERSION_NUMBER >= 0x00907000L)
-        count=0;
-        if (inlineCRLs) {
-            for (vector<XSECCryptoX509CRL*>::const_iterator j=inlineCRLs->begin(); j!=inlineCRLs->end(); ++j) {
-                if ((*j)->getProviderName()==DSIGConstants::s_unicodeStrPROVOpenSSL) {
-                    // owned by store
-                    X509_STORE_add_crl(store, X509_CRL_dup(static_cast<OpenSSLCryptoX509CRL*>(*j)->getOpenSSLX509CRL()));
-                    ++count;
-                }
-            }
-        }
-        const vector<XSECCryptoX509CRL*>& crls = pkixInfo->getCRLs();
-        for (vector<XSECCryptoX509CRL*>::const_iterator j=crls.begin(); j!=crls.end(); ++j) {
-            if ((*j)->getProviderName()==DSIGConstants::s_unicodeStrPROVOpenSSL) {
-                // owned by store
-                X509_STORE_add_crl(store, X509_CRL_dup(static_cast<OpenSSLCryptoX509CRL*>(*j)->getOpenSSLX509CRL()));
-                ++count;
-            }
-        }
-        log.debug("supplied (%d) CRL(s)", count);
-        if (count > 0)
-            X509_STORE_set_flags(store, fullCRLChain ? (X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL) : (X509_V_FLAG_CRL_CHECK));
-#else
-        if ((inlineCRLs && !inlineCRLs->empty()) || !pkixInfo->getCRLs().empty()) {
-            log.warn("OpenSSL versions < 0.9.7 do not support CRL checking");
-        }
-#endif
 
         // AFAICT, EE and untrusted are passed in but not owned by the ctx.
 #if (OPENSSL_VERSION_NUMBER >= 0x00907000L)
         if (X509_STORE_CTX_init(&ctx,store,EE,untrusted)!=1) {
             log_openssl();
             log.error("unable to initialize X509_STORE_CTX");
-            sk_X509_free(CAstack);
             X509_STORE_free(store);
             return false;
         }
 #else
         X509_STORE_CTX_init(&ctx,store,EE,untrusted);
 #endif
-    
+
+        STACK_OF(X509)* CAstack = sk_X509_new_null();
+        const vector<XSECCryptoX509*>& CAcerts = pkixInfo->getTrustAnchors();
+        for (vector<XSECCryptoX509*>::const_iterator i=CAcerts.begin(); i!=CAcerts.end(); ++i) {
+            if ((*i)->getProviderName()==DSIGConstants::s_unicodeStrPROVOpenSSL) {
+                sk_X509_push(CAstack,static_cast<OpenSSLCryptoX509*>(*i)->getOpenSSLX509());
+                ++count;
+            }
+        }
+        log.debug("supplied (%d) CA certificate(s)", count);
+
         // Seems to be most efficient to just pass in the CA stack.
         X509_STORE_CTX_trusted_stack(&ctx,CAstack);
         X509_STORE_CTX_set_depth(&ctx,100);    // we check the depth down below
         X509_STORE_CTX_set_verify_cb(&ctx,error_callback);
-        
+
+        // Do a first pass verify. If CRLs aren't used, this is the only pass.
         int ret=X509_verify_cert(&ctx);
         if (ret==1) {
             // Now see if the depth was acceptable by counting the number of intermediates.
@@ -148,7 +315,89 @@ namespace {
                 ret=0;
             }
         }
-        
+
+        if (useCRL) {
+#if (OPENSSL_VERSION_NUMBER >= 0x00907000L)
+            // When we add CRLs, we have to be sure the nextUpdate hasn't passed, because OpenSSL won't accept
+            // the CRL in that case. If we end up not adding a CRL for a particular link in the chain, the
+            // validation will fail (if the fullChain option was set).
+            set<string> crlissuers;
+            time_t now = time(nullptr);
+            if (inlineCRLs) {
+                for (vector<XSECCryptoX509CRL*>::const_iterator j=inlineCRLs->begin(); j!=inlineCRLs->end(); ++j) {
+                    if ((*j)->getProviderName()==DSIGConstants::s_unicodeStrPROVOpenSSL &&
+                        (X509_cmp_time(X509_CRL_get_nextUpdate(static_cast<OpenSSLCryptoX509CRL*>(*j)->getOpenSSLX509CRL()), &now) > 0)) {
+                        // owned by store
+                        X509_STORE_add_crl(store, X509_CRL_dup(static_cast<OpenSSLCryptoX509CRL*>(*j)->getOpenSSLX509CRL()));
+                        string crlissuer(X509_NAME_to_string(X509_CRL_get_issuer(static_cast<OpenSSLCryptoX509CRL*>(*j)->getOpenSSLX509CRL())));
+                        if (!crlissuer.empty()) {
+                            log.debug("added inline CRL issued by (%s)", crlissuer.c_str());
+                            crlissuers.insert(crlissuer);
+                        }
+                    }
+                }
+            }
+            const vector<XSECCryptoX509CRL*>& crls = pkixInfo->getCRLs();
+            for (vector<XSECCryptoX509CRL*>::const_iterator j=crls.begin(); j!=crls.end(); ++j) {
+                if ((*j)->getProviderName()==DSIGConstants::s_unicodeStrPROVOpenSSL &&
+                    (X509_cmp_time(X509_CRL_get_nextUpdate(static_cast<OpenSSLCryptoX509CRL*>(*j)->getOpenSSLX509CRL()), &now) > 0)) {
+                    // owned by store
+                    X509_STORE_add_crl(store, X509_CRL_dup(static_cast<OpenSSLCryptoX509CRL*>(*j)->getOpenSSLX509CRL()));
+                    string crlissuer(X509_NAME_to_string(X509_CRL_get_issuer(static_cast<OpenSSLCryptoX509CRL*>(*j)->getOpenSSLX509CRL())));
+                    if (!crlissuer.empty()) {
+                        log.debug("added CRL issued by (%s)", crlissuer.c_str());
+                        crlissuers.insert(crlissuer);
+                    }
+                }
+            }
+
+            for (int i = 0; i < sk_X509_num(untrusted); ++i) {
+                X509 *cert = sk_X509_value(untrusted, i);
+                string crlissuer(X509_NAME_to_string(X509_get_issuer_name(cert)));
+                if (crlissuers.count(crlissuer)) {
+                   // We already have a CRL for this cert, so skip CRLDP processing for this one.
+                   continue;
+                }
+
+                bool foundUsableCDP = false;
+                STACK_OF(DIST_POINT)* dps = (STACK_OF(DIST_POINT)*)X509_get_ext_d2i(cert, NID_crl_distribution_points, nullptr, nullptr);
+                for (int ii = 0; !foundUsableCDP && ii < sk_DIST_POINT_num(dps); ++ii) {
+                    DIST_POINT* dp = sk_DIST_POINT_value(dps, ii);
+                    if (!dp->distpoint || dp->distpoint->type != 0)
+                        continue;
+                    for (int iii = 0; !foundUsableCDP && iii < sk_GENERAL_NAME_num(dp->distpoint->name.fullname); ++iii) {
+                        GENERAL_NAME* gen = sk_GENERAL_NAME_value(dp->distpoint->name.fullname, iii);
+                        // Only consider HTTP URIs, and stop after the first one we find.
+#ifdef HAVE_STRCASECMP
+                        if (gen->type == GEN_URI && (!strncasecmp((const char*)gen->d.ia5->data, "http:", 5))) {
+#else
+                        if (gen->type == GEN_URI && (!strnicmp((const char*)gen->d.ia5->data, "http:", 5))) {
+#endif
+                            const char* cdpuri = (const char*)gen->d.ia5->data;
+                            auto_ptr<XSECCryptoX509CRL> crl(getRemoteCRLs(cdpuri, log));
+                            if (crl.get() && crl->getProviderName()==DSIGConstants::s_unicodeStrPROVOpenSSL &&
+                                (isFreshCRL(crl.get()) || (ii == sk_DIST_POINT_num(dps)-1 && iii == sk_GENERAL_NAME_num(dp->distpoint->name.fullname)-1))) {
+                                // owned by store
+                                X509_STORE_add_crl(store, X509_CRL_dup(static_cast<OpenSSLCryptoX509CRL*>(crl.get())->getOpenSSLX509CRL()));
+                                log.debug("added CRL issued by (%s)", crlissuer.c_str());
+                                crlissuers.insert(crlissuer);
+                                foundUsableCDP = true;
+                            }
+                        }
+                    }
+                }
+                sk_DIST_POINT_free(dps);
+            }
+
+            // Do a second pass verify with CRLs in place.
+            X509_STORE_CTX_set_flags(&ctx, fullCRLChain ? (X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL) : (X509_V_FLAG_CRL_CHECK));
+            ret=X509_verify_cert(&ctx);
+#else
+            log.warn("CRL checking is enabled, but OpenSSL version is too old");
+            ret = 0;
+#endif
+        }
+
         // Clean up...
         X509_STORE_CTX_cleanup(&ctx);
         X509_STORE_free(store);
@@ -162,7 +411,8 @@ namespace {
         return false;
     }
 
-    static XMLCh fullCRLChain[] = UNICODE_LITERAL_12(f,u,l,l,C,R,L,C,h,a,i,n);
+    static XMLCh fullCRLChain[] =              UNICODE_LITERAL_12(f,u,l,l,C,R,L,C,h,a,i,n);
+       static XMLCh checkRevocation[] =        UNICODE_LITERAL_15(c,h,e,c,k,R,e,v,o,c,a,t,i,o,n);
 };
 
 AbstractPKIXTrustEngine::PKIXValidationInfoIterator::PKIXValidationInfoIterator()
@@ -174,8 +424,19 @@ AbstractPKIXTrustEngine::PKIXValidationInfoIterator::~PKIXValidationInfoIterator
 }
 
 AbstractPKIXTrustEngine::AbstractPKIXTrustEngine(const xercesc::DOMElement* e)
-    : TrustEngine(e), m_fullCRLChain(XMLHelper::getAttrBool(e, false, fullCRLChain))
+       : TrustEngine(e),
+               m_fullCRLChain(XMLHelper::getAttrBool(e, false, fullCRLChain)),
+               m_checkRevocation(XMLHelper::getAttrString(e, nullptr, checkRevocation))
 {
+    if (m_fullCRLChain) {
+        Category::getInstance(XMLTOOLING_LOGCAT".TrustEngine.PKIX").warn(
+            "fullCRLChain option is deprecated, setting checkRevocation to \"fullChain\""
+            );
+        m_checkRevocation = "fullChain";
+    }
+    else if (m_checkRevocation == "fullChain") {
+        m_fullCRLChain = true; // in case anything's using this
+    }
 }
 
 AbstractPKIXTrustEngine::~AbstractPKIXTrustEngine()
@@ -348,7 +609,14 @@ bool AbstractPKIXTrustEngine::validateWithCRLs(
 
     auto_ptr<PKIXValidationInfoIterator> pkix(getPKIXValidationInfoIterator(credResolver, criteria));
     while (pkix->next()) {
-        if (::validate(certEE,certChain,pkix.get(),m_fullCRLChain,inlineCRLs)) {
+        if (::validate(
+                               certEE,
+                               certChain,
+                               pkix.get(),
+                               (m_checkRevocation=="entityOnly" || m_checkRevocation=="fullChain"),
+                               (m_checkRevocation=="fullChain"),
+                               (m_checkRevocation=="entityOnly" || m_checkRevocation=="fullChain") ? inlineCRLs : nullptr
+                               )) {
             return true;
         }
     }
@@ -522,10 +790,21 @@ bool AbstractPKIXTrustEngine::validate(
             log.debug(ex.what());
         }
     }
-    
-    if (certEE)
-        return validate(certEE,certs,credResolver,criteria);
-        
-    log.debug("failed to verify signature with embedded certificates");
-    return false;
+
+    if (!certEE) {
+        log.debug("failed to verify signature with embedded certificates");
+        return false;
+    }
+    else if (certEE->getProviderName()!=DSIGConstants::s_unicodeStrPROVOpenSSL) {
+        log.error("only the OpenSSL XSEC provider is supported");
+        return false;
+    }
+
+    STACK_OF(X509)* untrusted=sk_X509_new_null();
+    for (vector<XSECCryptoX509*>::const_iterator i=certs.begin(); i!=certs.end(); ++i)
+        sk_X509_push(untrusted,static_cast<OpenSSLCryptoX509*>(*i)->getOpenSSLX509());
+    const vector<XSECCryptoX509CRL*>& crls = x509cred->getCRLs();
+    bool ret = validateWithCRLs(static_cast<OpenSSLCryptoX509*>(certEE)->getOpenSSLX509(), untrusted, credResolver, criteria, &crls);
+    sk_X509_free(untrusted);
+    return ret;
 }