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-rw-r--r--dnsdist-secpoll.cc248
1 files changed, 248 insertions, 0 deletions
diff --git a/dnsdist-secpoll.cc b/dnsdist-secpoll.cc
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+++ b/dnsdist-secpoll.cc
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+/*
+ * This file is part of PowerDNS or dnsdist.
+ * Copyright -- PowerDNS.COM B.V. and its contributors
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * In addition, for the avoidance of any doubt, permission is granted to
+ * link this program with OpenSSL and to (re)distribute the binaries
+ * produced as the result of such linking.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "dnsdist-secpoll.hh"
+#ifndef DISABLE_SECPOLL
+
+#include <vector>
+
+#ifdef HAVE_LIBSODIUM
+#include <sodium.h>
+#endif /* HAVE_LIBSODIUM */
+
+#include "dnsparser.hh"
+#include "dolog.hh"
+#include "iputils.hh"
+#include "misc.hh"
+#include "sstuff.hh"
+
+#include "dnsdist.hh"
+#include "dnsdist-random.hh"
+
+#ifndef PACKAGEVERSION
+#define PACKAGEVERSION PACKAGE_VERSION
+#endif
+
+static std::string getFirstTXTAnswer(const std::string& answer)
+{
+ if (answer.size() <= sizeof(struct dnsheader)) {
+ throw std::runtime_error("Looking for a TXT record in an answer smaller than the DNS header");
+ }
+
+ const struct dnsheader* dh = reinterpret_cast<const struct dnsheader*>(answer.data());
+ PacketReader pr(answer);
+ uint16_t qdcount = ntohs(dh->qdcount);
+ uint16_t ancount = ntohs(dh->ancount);
+
+ DNSName rrname;
+ uint16_t rrtype;
+ uint16_t rrclass;
+
+ size_t idx = 0;
+ /* consume qd */
+ for(; idx < qdcount; idx++) {
+ rrname = pr.getName();
+ rrtype = pr.get16BitInt();
+ rrclass = pr.get16BitInt();
+ (void) rrtype;
+ (void) rrclass;
+ }
+
+ /* parse AN */
+ for (idx = 0; idx < ancount; idx++) {
+ string blob;
+ struct dnsrecordheader ah;
+ rrname = pr.getName();
+ pr.getDnsrecordheader(ah);
+
+ if (ah.d_type == QType::TXT) {
+ string txt;
+ pr.xfrText(txt);
+
+ return txt;
+ }
+ else {
+ pr.xfrBlob(blob);
+ }
+ }
+
+ throw std::runtime_error("No TXT record in answer");
+}
+
+static std::string getSecPollStatus(const std::string& queriedName, int timeout=2)
+{
+ const DNSName sentName(queriedName);
+ std::vector<uint8_t> packet;
+ DNSPacketWriter pw(packet, sentName, QType::TXT);
+ pw.getHeader()->id = dnsdist::getRandomDNSID();
+ pw.getHeader()->rd = 1;
+
+ const auto& resolversForStub = getResolvers("/etc/resolv.conf");
+
+ for(const auto& dest : resolversForStub) {
+ Socket sock(dest.sin4.sin_family, SOCK_DGRAM);
+ sock.setNonBlocking();
+ sock.connect(dest);
+ sock.send(string(packet.begin(), packet.end()));
+
+ string reply;
+ int ret = waitForData(sock.getHandle(), timeout, 0);
+ if (ret < 0) {
+ if (g_verbose) {
+ warnlog("Error while waiting for the secpoll response from stub resolver %s: %d", dest.toString(), ret);
+ }
+ continue;
+ }
+ else if (ret == 0) {
+ if (g_verbose) {
+ warnlog("Timeout while waiting for the secpoll response from stub resolver %s", dest.toString());
+ }
+ continue;
+ }
+
+ try {
+ sock.read(reply);
+ }
+ catch(const std::exception& e) {
+ if (g_verbose) {
+ warnlog("Error while reading for the secpoll response from stub resolver %s: %s", dest.toString(), e.what());
+ }
+ continue;
+ }
+
+ if (reply.size() <= sizeof(struct dnsheader)) {
+ if (g_verbose) {
+ warnlog("Too short answer of size %d received from the secpoll stub resolver %s", reply.size(), dest.toString());
+ }
+ continue;
+ }
+
+ struct dnsheader d;
+ memcpy(&d, reply.c_str(), sizeof(d));
+ if (d.id != pw.getHeader()->id) {
+ if (g_verbose) {
+ warnlog("Invalid ID (%d / %d) received from the secpoll stub resolver %s", d.id, pw.getHeader()->id, dest.toString());
+ }
+ continue;
+ }
+
+ if (d.rcode != RCode::NoError) {
+ if (g_verbose) {
+ warnlog("Response code '%s' received from the secpoll stub resolver %s for '%s'", RCode::to_s(d.rcode), dest.toString(), queriedName);
+ }
+
+ /* no need to try another resolver if the domain does not exist */
+ if (d.rcode == RCode::NXDomain) {
+ throw std::runtime_error("Unable to get a valid Security Status update");
+ }
+ continue;
+ }
+
+ if (ntohs(d.qdcount) != 1 || ntohs(d.ancount) != 1) {
+ if (g_verbose) {
+ warnlog("Invalid answer (qdcount %d / ancount %d) received from the secpoll stub resolver %s", ntohs(d.qdcount), ntohs(d.ancount), dest.toString());
+ }
+ continue;
+ }
+
+ uint16_t receivedType;
+ uint16_t receivedClass;
+ DNSName receivedName(reply.c_str(), reply.size(), sizeof(dnsheader), false, &receivedType, &receivedClass);
+
+ if (receivedName != sentName || receivedType != QType::TXT || receivedClass != QClass::IN) {
+ if (g_verbose) {
+ warnlog("Invalid answer, either the qname (%s / %s), qtype (%s / %s) or qclass (%s / %s) does not match, received from the secpoll stub resolver %s", receivedName, sentName, QType(receivedType).toString(), QType(QType::TXT).toString(), QClass(receivedClass).toString(), QClass::IN.toString(), dest.toString());
+ }
+ continue;
+ }
+
+ return getFirstTXTAnswer(reply);
+ }
+
+ throw std::runtime_error("Unable to get a valid Security Status update");
+}
+
+static bool g_secPollDone{false};
+std::string g_secPollSuffix{"secpoll.powerdns.com."};
+time_t g_secPollInterval{3600};
+
+void doSecPoll(const std::string& suffix)
+{
+ if (suffix.empty()) {
+ return;
+ }
+
+ const std::string pkgv(PACKAGEVERSION);
+ bool releaseVersion = std::count(pkgv.begin(), pkgv.end(), '.') == 2;
+ const std::string version = "dnsdist-" + pkgv;
+ std::string queriedName = version.substr(0, 63) + ".security-status." + suffix;
+
+ if (*queriedName.rbegin() != '.') {
+ queriedName += '.';
+ }
+
+ boost::replace_all(queriedName, "+", "_");
+ boost::replace_all(queriedName, "~", "_");
+
+ try {
+ std::string status = getSecPollStatus(queriedName);
+ pair<string, string> split = splitField(unquotify(status), ' ');
+
+ int securityStatus = std::stoi(split.first);
+ std::string securityMessage = split.second;
+
+ if(securityStatus == 1 && !g_secPollDone) {
+ warnlog("Polled security status of version %s at startup, no known issues reported: %s", std::string(VERSION), securityMessage);
+ }
+ if(securityStatus == 2) {
+ errlog("PowerDNS DNSDist Security Update Recommended: %s", securityMessage);
+ }
+ else if(securityStatus == 3) {
+ errlog("PowerDNS DNSDist Security Update Mandatory: %s", securityMessage);
+ }
+
+ g_stats.securityStatus = securityStatus;
+ g_secPollDone = true;
+ return;
+ }
+ catch(const std::exception& e) {
+ if (releaseVersion) {
+ warnlog("Error while retrieving the security update for version %s: %s", version, e.what());
+ }
+ else if (!g_secPollDone) {
+ infolog("Error while retrieving the security update for version %s: %s", version, e.what());
+ }
+ }
+
+ if (releaseVersion) {
+ warnlog("Failed to retrieve security status update for '%s' on %s", pkgv, queriedName);
+ }
+ else if (!g_secPollDone) {
+ infolog("Not validating response for security status update, this is a non-release version.");
+
+ /* for non-released versions, there is no use sending the same message several times,
+ let's just accept that there will be no security polling for this exact version */
+ g_secPollDone = true;
+ }
+}
+
+#endif /* DISABLE_SECPOLL */