src/modules/extra/m_ssl_mbedtls.cpp

   1 /*
   2  * InspIRCd -- Internet Relay Chat Daemon
   3  *
   4  *   Copyright (C) 2016 Attila Molnar <attilamolnar@hush.com>
   5  *
   6  * This file is part of InspIRCd.  InspIRCd is free software: you can
   7  * redistribute it and/or modify it under the terms of the GNU General Public
   8  * License as published by the Free Software Foundation, version 2.
   9  *
  10  * This program is distributed in the hope that it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  12  * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
  13  * details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17  */
  18
  19
  20 /* $LinkerFlags: -lmbedtls */
  21
  22 #include "inspircd.h"
  23 #include "modules/ssl.h"
  24
  25 #include <mbedtls/ctr_drbg.h>
  26 #include <mbedtls/dhm.h>
  27 #include <mbedtls/ecp.h>
  28 #include <mbedtls/entropy.h>
  29 #include <mbedtls/error.h>
  30 #include <mbedtls/md.h>
  31 #include <mbedtls/pk.h>
  32 #include <mbedtls/ssl.h>
  33 #include <mbedtls/ssl_ciphersuites.h>
  34 #include <mbedtls/version.h>
  35 #include <mbedtls/x509.h>
  36 #include <mbedtls/x509_crt.h>
  37 #include <mbedtls/x509_crl.h>
  38
  39 #ifdef INSPIRCD_MBEDTLS_LIBRARY_DEBUG
  40 #include <mbedtls/debug.h>
  41 #endif
  42
  43 namespace mbedTLS
  44 {
  45         class Exception : public ModuleException
  46         {
  47          public:
  48                 Exception(const std::string& reason)
  49                         : ModuleException(reason) { }
  50         };
  51
  52         std::string ErrorToString(int errcode)
  53         {
  54                 char buf[256];
  55                 mbedtls_strerror(errcode, buf, sizeof(buf));
  56                 return buf;
  57         }
  58
  59         void ThrowOnError(int errcode, const char* msg)
  60         {
  61                 if (errcode != 0)
  62                 {
  63                         std::string reason = msg;
  64                         reason.append(" :").append(ErrorToString(errcode));
  65                         throw Exception(reason);
  66                 }
  67         }
  68
  69         template <typename T, void (*init)(T*), void (*deinit)(T*)>
  70         class RAIIObj
  71         {
  72                 T obj;
  73
  74          public:
  75                 RAIIObj()
  76                 {
  77                         init(&obj);
  78                 }
  79
  80                 ~RAIIObj()
  81                 {
  82                         deinit(&obj);
  83                 }
  84
  85                 T* get() { return &obj; }
  86                 const T* get() const { return &obj; }
  87         };
  88
  89         typedef RAIIObj<mbedtls_entropy_context, mbedtls_entropy_init, mbedtls_entropy_free> Entropy;
  90
  91         class CTRDRBG : private RAIIObj<mbedtls_ctr_drbg_context, mbedtls_ctr_drbg_init, mbedtls_ctr_drbg_free>
  92         {
  93          public:
  94                 bool Seed(Entropy& entropy)
  95                 {
  96                         return (mbedtls_ctr_drbg_seed(get(), mbedtls_entropy_func, entropy.get(), NULL, 0) == 0);
  97                 }
  98
  99                 void SetupConf(mbedtls_ssl_config* conf)
 100                 {
 101                         mbedtls_ssl_conf_rng(conf, mbedtls_ctr_drbg_random, get());
 102                 }
 103         };
 104
 105         class DHParams : public RAIIObj<mbedtls_dhm_context, mbedtls_dhm_init, mbedtls_dhm_free>
 106         {
 107          public:
 108                 void set(const std::string& dhstr)
 109                 {
 110                         // Last parameter is buffer size, must include the terminating null
 111                         int ret = mbedtls_dhm_parse_dhm(get(), reinterpret_cast<const unsigned char*>(dhstr.c_str()), dhstr.size()+1);
 112                         ThrowOnError(ret, "Unable to import DH params");
 113                 }
 114         };
 115
 116         class X509Key : public RAIIObj<mbedtls_pk_context, mbedtls_pk_init, mbedtls_pk_free>
 117         {
 118          public:
 119                 /** Import */
 120                 X509Key(const std::string& keystr)
 121                 {
 122                         int ret = mbedtls_pk_parse_key(get(), reinterpret_cast<const unsigned char*>(keystr.c_str()), keystr.size()+1, NULL, 0);
 123                         ThrowOnError(ret, "Unable to import private key");
 124                 }
 125         };
 126
 127         class Ciphersuites
 128         {
 129                 std::vector<int> list;
 130
 131          public:
 132                 Ciphersuites(const std::string& str)
 133                 {
 134                         // mbedTLS uses the ciphersuite format "TLS-ECDHE-RSA-WITH-AES-128-GCM-SHA256" internally.
 135                         // This is a bit verbose, so we make life a bit simpler for admins by not requiring them to supply the static parts.
 136                         irc::sepstream ss(str, ':');
 137                         for (std::string token; ss.GetToken(token); )
 138                         {
 139                                 // Prepend "TLS-" if not there
 140                                 if (token.compare(0, 4, "TLS-", 4))
 141                                         token.insert(0, "TLS-");
 142
 143                                 const int id = mbedtls_ssl_get_ciphersuite_id(token.c_str());
 144                                 if (!id)
 145                                         throw Exception("Unknown ciphersuite " + token);
 146                                 list.push_back(id);
 147                         }
 148                         list.push_back(0);
 149                 }
 150
 151                 const int* get() const { return &list.front(); }
 152                 bool empty() const { return (list.size() <= 1); }
 153         };
 154
 155         class Curves
 156         {
 157                 std::vector<mbedtls_ecp_group_id> list;
 158
 159          public:
 160                 Curves(const std::string& str)
 161                 {
 162                         irc::sepstream ss(str, ':');
 163                         for (std::string token; ss.GetToken(token); )
 164                         {
 165                                 const mbedtls_ecp_curve_info* curve = mbedtls_ecp_curve_info_from_name(token.c_str());
 166                                 if (!curve)
 167                                         throw Exception("Unknown curve " + token);
 168                                 list.push_back(curve->grp_id);
 169                         }
 170                         list.push_back(MBEDTLS_ECP_DP_NONE);
 171                 }
 172
 173                 const mbedtls_ecp_group_id* get() const { return &list.front(); }
 174                 bool empty() const { return (list.size() <= 1); }
 175         };
 176
 177         class X509CertList : public RAIIObj<mbedtls_x509_crt, mbedtls_x509_crt_init, mbedtls_x509_crt_free>
 178         {
 179          public:
 180                 /** Import or create empty */
 181                 X509CertList(const std::string& certstr, bool allowempty = false)
 182                 {
 183                         if ((allowempty) && (certstr.empty()))
 184                                 return;
 185                         int ret = mbedtls_x509_crt_parse(get(), reinterpret_cast<const unsigned char*>(certstr.c_str()), certstr.size()+1);
 186                         ThrowOnError(ret, "Unable to load certificates");
 187                 }
 188
 189                 bool empty() const { return (get()->raw.p != NULL); }
 190         };
 191
 192         class X509CRL : public RAIIObj<mbedtls_x509_crl, mbedtls_x509_crl_init, mbedtls_x509_crl_free>
 193         {
 194          public:
 195                 X509CRL(const std::string& crlstr)
 196                 {
 197                         if (crlstr.empty())
 198                                 return;
 199                         int ret = mbedtls_x509_crl_parse(get(), reinterpret_cast<const unsigned char*>(crlstr.c_str()), crlstr.size()+1);
 200                         ThrowOnError(ret, "Unable to load CRL");
 201                 }
 202         };
 203
 204         class X509Credentials
 205         {
 206                 /** Private key
 207                  */
 208                 X509Key key;
 209
 210                 /** Certificate list, presented to the peer
 211                  */
 212                 X509CertList certs;
 213
 214          public:
 215                 X509Credentials(const std::string& certstr, const std::string& keystr)
 216                         : key(keystr)
 217                         , certs(certstr)
 218                 {
 219                         // Verify that one of the certs match the private key
 220                         bool found = false;
 221                         for (mbedtls_x509_crt* cert = certs.get(); cert; cert = cert->next)
 222                         {
 223                                 if (mbedtls_pk_check_pair(&cert->pk, key.get()) == 0)
 224                                 {
 225                                         found = true;
 226                                         break;
 227                                 }
 228                         }
 229                         if (!found)
 230                                 throw Exception("Public/private key pair does not match");
 231                 }
 232
 233                 mbedtls_pk_context* getkey() { return key.get(); }
 234                 mbedtls_x509_crt* getcerts() { return certs.get(); }
 235         };
 236
 237         class Context
 238         {
 239                 mbedtls_ssl_config conf;
 240
 241 #ifdef INSPIRCD_MBEDTLS_LIBRARY_DEBUG
 242                 static void DebugLogFunc(void* userptr, int level, const char* file, int line, const char* msg)
 243                 {
 244                         // Remove trailing \n
 245                         size_t len = strlen(msg);
 246                         if ((len > 0) && (msg[len-1] == '\n'))
 247                                 len--;
 248                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "%s:%d %.*s", file, line, len, msg);
 249                 }
 250 #endif
 251
 252          public:
 253                 Context(CTRDRBG& ctrdrbg, unsigned int endpoint)
 254                 {
 255                         mbedtls_ssl_config_init(&conf);
 256 #ifdef INSPIRCD_MBEDTLS_LIBRARY_DEBUG
 257                         mbedtls_debug_set_threshold(INT_MAX);
 258                         mbedtls_ssl_conf_dbg(&conf, DebugLogFunc, NULL);
 259 #endif
 260
 261                         // TODO: check ret of mbedtls_ssl_config_defaults
 262                         mbedtls_ssl_config_defaults(&conf, endpoint, MBEDTLS_SSL_TRANSPORT_STREAM, MBEDTLS_SSL_PRESET_DEFAULT);
 263                         ctrdrbg.SetupConf(&conf);
 264                 }
 265
 266                 ~Context()
 267                 {
 268                         mbedtls_ssl_config_free(&conf);
 269                 }
 270
 271                 void SetMinDHBits(unsigned int mindh)
 272                 {
 273                         mbedtls_ssl_conf_dhm_min_bitlen(&conf, mindh);
 274                 }
 275
 276                 void SetDHParams(DHParams& dh)
 277                 {
 278                         mbedtls_ssl_conf_dh_param_ctx(&conf, dh.get());
 279                 }
 280
 281                 void SetX509CertAndKey(X509Credentials& x509cred)
 282                 {
 283                         mbedtls_ssl_conf_own_cert(&conf, x509cred.getcerts(), x509cred.getkey());
 284                 }
 285
 286                 void SetCiphersuites(const Ciphersuites& ciphersuites)
 287                 {
 288                         mbedtls_ssl_conf_ciphersuites(&conf, ciphersuites.get());
 289                 }
 290
 291                 void SetCurves(const Curves& curves)
 292                 {
 293                         mbedtls_ssl_conf_curves(&conf, curves.get());
 294                 }
 295
 296                 void SetVersion(int minver, int maxver)
 297                 {
 298                         // SSL v3 support cannot be enabled
 299                         if (minver)
 300                                 mbedtls_ssl_conf_min_version(&conf, MBEDTLS_SSL_MAJOR_VERSION_3, minver);
 301                         if (maxver)
 302                                 mbedtls_ssl_conf_max_version(&conf, MBEDTLS_SSL_MAJOR_VERSION_3, maxver);
 303                 }
 304
 305                 void SetCA(X509CertList& certs, X509CRL& crl)
 306                 {
 307                         mbedtls_ssl_conf_ca_chain(&conf, certs.get(), crl.get());
 308                 }
 309
 310                 void SetOptionalVerifyCert()
 311                 {
 312                         mbedtls_ssl_conf_authmode(&conf, MBEDTLS_SSL_VERIFY_OPTIONAL);
 313                 }
 314
 315                 const mbedtls_ssl_config* GetConf() const { return &conf; }
 316         };
 317
 318         class Hash
 319         {
 320                 const mbedtls_md_info_t* md;
 321
 322                 /** Buffer where cert hashes are written temporarily
 323                  */
 324                 mutable std::vector<unsigned char> buf;
 325
 326          public:
 327                 Hash(std::string hashstr)
 328                 {
 329                         std::transform(hashstr.begin(), hashstr.end(), hashstr.begin(), ::toupper);
 330                         md = mbedtls_md_info_from_string(hashstr.c_str());
 331                         if (!md)
 332                                 throw Exception("Unknown hash: " + hashstr);
 333
 334                         buf.resize(mbedtls_md_get_size(md));
 335                 }
 336
 337                 std::string hash(const unsigned char* input, size_t length) const
 338                 {
 339                         mbedtls_md(md, input, length, &buf.front());
 340                         return BinToHex(&buf.front(), buf.size());
 341                 }
 342         };
 343
 344         class Profile : public refcountbase
 345         {
 346                 /** Name of this profile
 347                  */
 348                 const std::string name;
 349
 350                 X509Credentials x509cred;
 351
 352                 /** Ciphersuites to use
 353                  */
 354                 Ciphersuites ciphersuites;
 355
 356                 /** Curves accepted for use in ECDHE and in the peer's end-entity certificate
 357                  */
 358                 Curves curves;
 359
 360                 Context serverctx;
 361                 Context clientctx;
 362
 363                 DHParams dhparams;
 364
 365                 X509CertList cacerts;
 366
 367                 X509CRL crl;
 368
 369                 /** Hashing algorithm to use when generating certificate fingerprints
 370                  */
 371                 Hash hash;
 372
 373                 /** Rough max size of records to send
 374                  */
 375                 const unsigned int outrecsize;
 376
 377                 Profile(const std::string& profilename, const std::string& certstr, const std::string& keystr,
 378                                 const std::string& dhstr, unsigned int mindh, const std::string& hashstr,
 379                                 const std::string& ciphersuitestr, const std::string& curvestr,
 380                                 const std::string& castr, const std::string& crlstr,
 381                                 unsigned int recsize,
 382                                 CTRDRBG& ctrdrbg,
 383                                 int minver, int maxver,
 384                                 bool requestclientcert
 385                                 )
 386                         : name(profilename)
 387                         , x509cred(certstr, keystr)
 388                         , ciphersuites(ciphersuitestr)
 389                         , curves(curvestr)
 390                         , serverctx(ctrdrbg, MBEDTLS_SSL_IS_SERVER)
 391                         , clientctx(ctrdrbg, MBEDTLS_SSL_IS_CLIENT)
 392                         , cacerts(castr, true)
 393                         , crl(crlstr)
 394                         , hash(hashstr)
 395                         , outrecsize(recsize)
 396                 {
 397                         serverctx.SetX509CertAndKey(x509cred);
 398                         clientctx.SetX509CertAndKey(x509cred);
 399                         clientctx.SetMinDHBits(mindh);
 400
 401                         if (!ciphersuites.empty())
 402                         {
 403                                 serverctx.SetCiphersuites(ciphersuites);
 404                                 clientctx.SetCiphersuites(ciphersuites);
 405                         }
 406
 407                         if (!curves.empty())
 408                         {
 409                                 serverctx.SetCurves(curves);
 410                                 clientctx.SetCurves(curves);
 411                         }
 412
 413                         serverctx.SetVersion(minver, maxver);
 414                         clientctx.SetVersion(minver, maxver);
 415
 416                         if (!dhstr.empty())
 417                         {
 418                                 dhparams.set(dhstr);
 419                                 serverctx.SetDHParams(dhparams);
 420                         }
 421
 422                         clientctx.SetOptionalVerifyCert();
 423                         // The default for servers is to not request a client certificate from the peer
 424                         if (requestclientcert)
 425                         {
 426                                 serverctx.SetOptionalVerifyCert();
 427                                 serverctx.SetCA(cacerts, crl);
 428                         }
 429                 }
 430
 431                 static std::string ReadFile(const std::string& filename)
 432                 {
 433                         FileReader reader(filename);
 434                         std::string ret = reader.GetString();
 435                         if (ret.empty())
 436                                 throw Exception("Cannot read file " + filename);
 437                         return ret;
 438                 }
 439
 440          public:
 441                 static reference<Profile> Create(const std::string& profilename, ConfigTag* tag, CTRDRBG& ctr_drbg)
 442                 {
 443                         const std::string certstr = ReadFile(tag->getString("certfile", "cert.pem"));
 444                         const std::string keystr = ReadFile(tag->getString("keyfile", "key.pem"));
 445                         const std::string dhstr = ReadFile(tag->getString("dhfile", "dhparams.pem"));
 446
 447                         const std::string ciphersuitestr = tag->getString("ciphersuites");
 448                         const std::string curvestr = tag->getString("curves");
 449                         unsigned int mindh = tag->getInt("mindhbits", 2048);
 450                         std::string hashstr = tag->getString("hash", "sha256");
 451
 452                         std::string crlstr;
 453                         std::string castr = tag->getString("cafile");
 454                         if (!castr.empty())
 455                         {
 456                                 castr = ReadFile(castr);
 457                                 crlstr = tag->getString("crlfile");
 458                                 if (!crlstr.empty())
 459                                         crlstr = ReadFile(crlstr);
 460                         }
 461
 462                         int minver = tag->getInt("minver");
 463                         int maxver = tag->getInt("maxver");
 464                         unsigned int outrecsize = tag->getInt("outrecsize", 2048, 512, 16384);
 465                         const bool requestclientcert = tag->getBool("requestclientcert", true);
 466                         return new Profile(profilename, certstr, keystr, dhstr, mindh, hashstr, ciphersuitestr, curvestr, castr, crlstr, outrecsize, ctr_drbg, minver, maxver, requestclientcert);
 467                 }
 468
 469                 /** Set up the given session with the settings in this profile
 470                  */
 471                 void SetupClientSession(mbedtls_ssl_context* sess)
 472                 {
 473                         mbedtls_ssl_setup(sess, clientctx.GetConf());
 474                 }
 475
 476                 void SetupServerSession(mbedtls_ssl_context* sess)
 477                 {
 478                         mbedtls_ssl_setup(sess, serverctx.GetConf());
 479                 }
 480
 481                 const std::string& GetName() const { return name; }
 482                 X509Credentials& GetX509Credentials() { return x509cred; }
 483                 unsigned int GetOutgoingRecordSize() const { return outrecsize; }
 484                 const Hash& GetHash() const { return hash; }
 485         };
 486 }
 487
 488 class mbedTLSIOHook : public SSLIOHook
 489 {
 490         enum Status
 491         {
 492                 ISSL_NONE,
 493                 ISSL_HANDSHAKING,
 494                 ISSL_HANDSHAKEN
 495         };
 496
 497         mbedtls_ssl_context sess;
 498         Status status;
 499         reference<mbedTLS::Profile> profile;
 500
 501         void CloseSession()
 502         {
 503                 if (status == ISSL_NONE)
 504                         return;
 505
 506                 mbedtls_ssl_close_notify(&sess);
 507                 mbedtls_ssl_free(&sess);
 508                 certificate = NULL;
 509                 status = ISSL_NONE;
 510         }
 511
 512         // Returns 1 if handshake succeeded, 0 if it is still in progress, -1 if it failed
 513         int Handshake(StreamSocket* sock)
 514         {
 515                 int ret = mbedtls_ssl_handshake(&sess);
 516                 if (ret == 0)
 517                 {
 518                         // Change the seesion state
 519                         this->status = ISSL_HANDSHAKEN;
 520
 521                         VerifyCertificate();
 522
 523                         // Finish writing, if any left
 524                         SocketEngine::ChangeEventMask(sock, FD_WANT_POLL_READ | FD_WANT_NO_WRITE | FD_ADD_TRIAL_WRITE);
 525
 526                         return 1;
 527                 }
 528
 529                 this->status = ISSL_HANDSHAKING;
 530                 if (ret == MBEDTLS_ERR_SSL_WANT_READ)
 531                 {
 532                         SocketEngine::ChangeEventMask(sock, FD_WANT_POLL_READ | FD_WANT_NO_WRITE);
 533                         return 0;
 534                 }
 535                 else if (ret == MBEDTLS_ERR_SSL_WANT_WRITE)
 536                 {
 537                         SocketEngine::ChangeEventMask(sock, FD_WANT_NO_READ | FD_WANT_SINGLE_WRITE);
 538                         return 0;
 539                 }
 540
 541                 sock->SetError("Handshake Failed - " + mbedTLS::ErrorToString(ret));
 542                 CloseSession();
 543                 return -1;
 544         }
 545
 546         // Returns 1 if application I/O should proceed, 0 if it must wait for the underlying protocol to progress, -1 on fatal error
 547         int PrepareIO(StreamSocket* sock)
 548         {
 549                 if (status == ISSL_HANDSHAKEN)
 550                         return 1;
 551                 else if (status == ISSL_HANDSHAKING)
 552                 {
 553                         // The handshake isn't finished, try to finish it
 554                         return Handshake(sock);
 555                 }
 556
 557                 CloseSession();
 558                 sock->SetError("No SSL session");
 559                 return -1;
 560         }
 561
 562         void VerifyCertificate()
 563         {
 564                 this->certificate = new ssl_cert;
 565                 const mbedtls_x509_crt* const cert = mbedtls_ssl_get_peer_cert(&sess);
 566                 if (!cert)
 567                 {
 568                         certificate->error = "No client certificate sent";
 569                         return;
 570                 }
 571
 572                 // If there is a certificate we can always generate a fingerprint
 573                 certificate->fingerprint = profile->GetHash().hash(cert->raw.p, cert->raw.len);
 574
 575                 // At this point mbedTLS verified the cert already, we just need to check the results
 576                 const uint32_t flags = mbedtls_ssl_get_verify_result(&sess);
 577                 if (flags == 0xFFFFFFFF)
 578                 {
 579                         certificate->error = "Internal error during verification";
 580                         return;
 581                 }
 582
 583                 if (flags == 0)
 584                 {
 585                         // Verification succeeded
 586                         certificate->trusted = true;
 587                 }
 588                 else
 589                 {
 590                         // Verification failed
 591                         certificate->trusted = false;
 592                         if ((flags & MBEDTLS_X509_BADCERT_EXPIRED) || (flags & MBEDTLS_X509_BADCERT_FUTURE))
 593                                 certificate->error = "Not activated, or expired certificate";
 594                 }
 595
 596                 certificate->unknownsigner = (flags & MBEDTLS_X509_BADCERT_NOT_TRUSTED);
 597                 certificate->revoked = (flags & MBEDTLS_X509_BADCERT_REVOKED);
 598                 certificate->invalid = ((flags & MBEDTLS_X509_BADCERT_BAD_KEY) || (flags & MBEDTLS_X509_BADCERT_BAD_MD) || (flags & MBEDTLS_X509_BADCERT_BAD_PK));
 599
 600                 GetDNString(&cert->subject, certificate->dn);
 601                 GetDNString(&cert->issuer, certificate->issuer);
 602         }
 603
 604         static void GetDNString(const mbedtls_x509_name* x509name, std::string& out)
 605         {
 606                 char buf[512];
 607                 const int ret = mbedtls_x509_dn_gets(buf, sizeof(buf), x509name);
 608                 if (ret <= 0)
 609                         return;
 610
 611                 out.assign(buf, ret);
 612         }
 613
 614         static int Pull(void* userptr, unsigned char* buffer, size_t size)
 615         {
 616                 StreamSocket* const sock = reinterpret_cast<StreamSocket*>(userptr);
 617                 if (sock->GetEventMask() & FD_READ_WILL_BLOCK)
 618                         return MBEDTLS_ERR_SSL_WANT_READ;
 619
 620                 const int ret = SocketEngine::Recv(sock, reinterpret_cast<char*>(buffer), size, 0);
 621                 if (ret < (int)size)
 622                 {
 623                         SocketEngine::ChangeEventMask(sock, FD_READ_WILL_BLOCK);
 624                         if ((ret == -1) && (SocketEngine::IgnoreError()))
 625                                 return MBEDTLS_ERR_SSL_WANT_READ;
 626                 }
 627                 return ret;
 628         }
 629
 630         static int Push(void* userptr, const unsigned char* buffer, size_t size)
 631         {
 632                 StreamSocket* const sock = reinterpret_cast<StreamSocket*>(userptr);
 633                 if (sock->GetEventMask() & FD_WRITE_WILL_BLOCK)
 634                         return MBEDTLS_ERR_SSL_WANT_WRITE;
 635
 636                 const int ret = SocketEngine::Send(sock, buffer, size, 0);
 637                 if (ret < (int)size)
 638                 {
 639                         SocketEngine::ChangeEventMask(sock, FD_WRITE_WILL_BLOCK);
 640                         if ((ret == -1) && (SocketEngine::IgnoreError()))
 641                                 return MBEDTLS_ERR_SSL_WANT_WRITE;
 642                 }
 643                 return ret;
 644         }
 645
 646  public:
 647         mbedTLSIOHook(IOHookProvider* hookprov, StreamSocket* sock, bool isserver, mbedTLS::Profile* sslprofile)
 648                 : SSLIOHook(hookprov)
 649                 , status(ISSL_NONE)
 650                 , profile(sslprofile)
 651         {
 652                 mbedtls_ssl_init(&sess);
 653                 if (isserver)
 654                         profile->SetupServerSession(&sess);
 655                 else
 656                         profile->SetupClientSession(&sess);
 657
 658                 mbedtls_ssl_set_bio(&sess, reinterpret_cast<void*>(sock), Push, Pull, NULL);
 659
 660                 sock->AddIOHook(this);
 661                 Handshake(sock);
 662         }
 663
 664         void OnStreamSocketClose(StreamSocket* sock) CXX11_OVERRIDE
 665         {
 666                 CloseSession();
 667         }
 668
 669         int OnStreamSocketRead(StreamSocket* sock, std::string& recvq) CXX11_OVERRIDE
 670         {
 671                 // Finish handshake if needed
 672                 int prepret = PrepareIO(sock);
 673                 if (prepret <= 0)
 674                         return prepret;
 675
 676                 // If we resumed the handshake then this->status will be ISSL_HANDSHAKEN.
 677                 char* const readbuf = ServerInstance->GetReadBuffer();
 678                 const size_t readbufsize = ServerInstance->Config->NetBufferSize;
 679                 int ret = mbedtls_ssl_read(&sess, reinterpret_cast<unsigned char*>(readbuf), readbufsize);
 680                 if (ret > 0)
 681                 {
 682                         recvq.append(readbuf, ret);
 683
 684                         // Schedule a read if there is still data in the mbedTLS buffer
 685                         if (mbedtls_ssl_get_bytes_avail(&sess) > 0)
 686                                 SocketEngine::ChangeEventMask(sock, FD_ADD_TRIAL_READ);
 687                         return 1;
 688                 }
 689                 else if (ret == MBEDTLS_ERR_SSL_WANT_READ)
 690                 {
 691                         SocketEngine::ChangeEventMask(sock, FD_WANT_POLL_READ);
 692                         return 0;
 693                 }
 694                 else if (ret == MBEDTLS_ERR_SSL_WANT_WRITE)
 695                 {
 696                         SocketEngine::ChangeEventMask(sock, FD_WANT_NO_READ | FD_WANT_SINGLE_WRITE);
 697                         return 0;
 698                 }
 699                 else if (ret == 0)
 700                 {
 701                         sock->SetError("Connection closed");
 702                         CloseSession();
 703                         return -1;
 704                 }
 705                 else // error or MBEDTLS_ERR_SSL_CLIENT_RECONNECT which we treat as an error
 706                 {
 707                         sock->SetError(mbedTLS::ErrorToString(ret));
 708                         CloseSession();
 709                         return -1;
 710                 }
 711         }
 712
 713         int OnStreamSocketWrite(StreamSocket* sock, StreamSocket::SendQueue& sendq) CXX11_OVERRIDE
 714         {
 715                 // Finish handshake if needed
 716                 int prepret = PrepareIO(sock);
 717                 if (prepret <= 0)
 718                         return prepret;
 719
 720                 // Session is ready for transferring application data
 721                 while (!sendq.empty())
 722                 {
 723                         FlattenSendQueue(sendq, profile->GetOutgoingRecordSize());
 724                         const StreamSocket::SendQueue::Element& buffer = sendq.front();
 725                         int ret = mbedtls_ssl_write(&sess, reinterpret_cast<const unsigned char*>(buffer.data()), buffer.length());
 726                         if (ret == (int)buffer.length())
 727                         {
 728                                 // Wrote entire record, continue sending
 729                                 sendq.pop_front();
 730                         }
 731                         else if (ret > 0)
 732                         {
 733                                 sendq.erase_front(ret);
 734                                 SocketEngine::ChangeEventMask(sock, FD_WANT_SINGLE_WRITE);
 735                                 return 0;
 736                         }
 737                         else if (ret == 0)
 738                         {
 739                                 sock->SetError("Connection closed");
 740                                 CloseSession();
 741                                 return -1;
 742                         }
 743                         else if (ret == MBEDTLS_ERR_SSL_WANT_WRITE)
 744                         {
 745                                 SocketEngine::ChangeEventMask(sock, FD_WANT_SINGLE_WRITE);
 746                                 return 0;
 747                         }
 748                         else if (ret == MBEDTLS_ERR_SSL_WANT_READ)
 749                         {
 750                                 SocketEngine::ChangeEventMask(sock, FD_WANT_POLL_READ);
 751                                 return 0;
 752                         }
 753                         else
 754                         {
 755                                 sock->SetError(mbedTLS::ErrorToString(ret));
 756                                 CloseSession();
 757                                 return -1;
 758                         }
 759                 }
 760
 761                 SocketEngine::ChangeEventMask(sock, FD_WANT_NO_WRITE);
 762                 return 1;
 763         }
 764
 765         void GetCiphersuite(std::string& out) const CXX11_OVERRIDE
 766         {
 767                 if (!IsHandshakeDone())
 768                         return;
 769                 out.append(mbedtls_ssl_get_version(&sess)).push_back('-');
 770
 771                 // All mbedTLS ciphersuite names currently begin with "TLS-" which provides no useful information so skip it, but be prepared if it changes
 772                 const char* const ciphersuitestr = mbedtls_ssl_get_ciphersuite(&sess);
 773                 const char prefix[] = "TLS-";
 774                 unsigned int skip = sizeof(prefix)-1;
 775                 if (strncmp(ciphersuitestr, prefix, sizeof(prefix)-1))
 776                         skip = 0;
 777                 out.append(ciphersuitestr + skip);
 778         }
 779
 780         bool IsHandshakeDone() const { return (status == ISSL_HANDSHAKEN); }
 781 };
 782
 783 class mbedTLSIOHookProvider : public refcountbase, public IOHookProvider
 784 {
 785         reference<mbedTLS::Profile> profile;
 786
 787  public:
 788         mbedTLSIOHookProvider(Module* mod, mbedTLS::Profile* prof)
 789                 : IOHookProvider(mod, "ssl/" + prof->GetName(), IOHookProvider::IOH_SSL)
 790                 , profile(prof)
 791         {
 792                 ServerInstance->Modules->AddService(*this);
 793         }
 794
 795         ~mbedTLSIOHookProvider()
 796         {
 797                 ServerInstance->Modules->DelService(*this);
 798         }
 799
 800         void OnAccept(StreamSocket* sock, irc::sockets::sockaddrs* client, irc::sockets::sockaddrs* server) CXX11_OVERRIDE
 801         {
 802                 new mbedTLSIOHook(this, sock, true, profile);
 803         }
 804
 805         void OnConnect(StreamSocket* sock) CXX11_OVERRIDE
 806         {
 807                 new mbedTLSIOHook(this, sock, false, profile);
 808         }
 809 };
 810
 811 class ModuleSSLmbedTLS : public Module
 812 {
 813         typedef std::vector<reference<mbedTLSIOHookProvider> > ProfileList;
 814
 815         mbedTLS::Entropy entropy;
 816         mbedTLS::CTRDRBG ctr_drbg;
 817         ProfileList profiles;
 818
 819         void ReadProfiles()
 820         {
 821                 // First, store all profiles in a new, temporary container. If no problems occur, swap the two
 822                 // containers; this way if something goes wrong we can go back and continue using the current profiles,
 823                 // avoiding unpleasant situations where no new SSL connections are possible.
 824                 ProfileList newprofiles;
 825
 826                 ConfigTagList tags = ServerInstance->Config->ConfTags("sslprofile");
 827                 if (tags.first == tags.second)
 828                 {
 829                         // No <sslprofile> tags found, create a profile named "mbedtls" from settings in the <mbedtls> block
 830                         const std::string defname = "mbedtls";
 831                         ConfigTag* tag = ServerInstance->Config->ConfValue(defname);
 832                         ServerInstance->Logs->Log(MODNAME, LOG_DEFAULT, "No <sslprofile> tags found; using settings from the <mbedtls> tag");
 833
 834                         try
 835                         {
 836                                 reference<mbedTLS::Profile> profile(mbedTLS::Profile::Create(defname, tag, ctr_drbg));
 837                                 newprofiles.push_back(new mbedTLSIOHookProvider(this, profile));
 838                         }
 839                         catch (CoreException& ex)
 840                         {
 841                                 throw ModuleException("Error while initializing the default SSL profile - " + ex.GetReason());
 842                         }
 843                 }
 844
 845                 for (ConfigIter i = tags.first; i != tags.second; ++i)
 846                 {
 847                         ConfigTag* tag = i->second;
 848                         if (tag->getString("provider") != "mbedtls")
 849                                 continue;
 850
 851                         std::string name = tag->getString("name");
 852                         if (name.empty())
 853                         {
 854                                 ServerInstance->Logs->Log(MODNAME, LOG_DEFAULT, "Ignoring <sslprofile> tag without name at " + tag->getTagLocation());
 855                                 continue;
 856                         }
 857
 858                         reference<mbedTLS::Profile> profile;
 859                         try
 860                         {
 861                                 profile = mbedTLS::Profile::Create(name, tag, ctr_drbg);
 862                         }
 863                         catch (CoreException& ex)
 864                         {
 865                                 throw ModuleException("Error while initializing SSL profile \"" + name + "\" at " + tag->getTagLocation() + " - " + ex.GetReason());
 866                         }
 867
 868                         newprofiles.push_back(new mbedTLSIOHookProvider(this, profile));
 869                 }
 870
 871                 // New profiles are ok, begin using them
 872                 // Old profiles are deleted when their refcount drops to zero
 873                 profiles.swap(newprofiles);
 874         }
 875
 876  public:
 877         void init() CXX11_OVERRIDE
 878         {
 879                 char verbuf[16]; // Should be at least 9 bytes in size
 880                 mbedtls_version_get_string(verbuf);
 881                 ServerInstance->Logs->Log(MODNAME, LOG_DEFAULT, "mbedTLS lib version %s module was compiled for " MBEDTLS_VERSION_STRING, verbuf);
 882
 883                 if (!ctr_drbg.Seed(entropy))
 884                         throw ModuleException("CTR DRBG seed failed");
 885                 ReadProfiles();
 886         }
 887
 888         void OnModuleRehash(User* user, const std::string &param) CXX11_OVERRIDE
 889         {
 890                 if (param != "ssl")
 891                         return;
 892
 893                 try
 894                 {
 895                         ReadProfiles();
 896                 }
 897                 catch (ModuleException& ex)
 898                 {
 899                         ServerInstance->Logs->Log(MODNAME, LOG_DEFAULT, ex.GetReason() + " Not applying settings.");
 900                 }
 901         }
 902
 903         void OnCleanup(int target_type, void* item) CXX11_OVERRIDE
 904         {
 905                 if (target_type != TYPE_USER)
 906                         return;
 907
 908                 LocalUser* user = IS_LOCAL(static_cast<User*>(item));
 909                 if ((user) && (user->eh.GetModHook(this)))
 910                 {
 911                         // User is using SSL, they're a local user, and they're using our IOHook.
 912                         // Potentially there could be multiple SSL modules loaded at once on different ports.
 913                         ServerInstance->Users.QuitUser(user, "SSL module unloading");
 914                 }
 915         }
 916
 917         ModResult OnCheckReady(LocalUser* user) CXX11_OVERRIDE
 918         {
 919                 const mbedTLSIOHook* const iohook = static_cast<mbedTLSIOHook*>(user->eh.GetModHook(this));
 920                 if ((iohook) && (!iohook->IsHandshakeDone()))
 921                         return MOD_RES_DENY;
 922                 return MOD_RES_PASSTHRU;
 923         }
 924
 925         Version GetVersion() CXX11_OVERRIDE
 926         {
 927                 return Version("Provides SSL support via mbedTLS (PolarSSL)", VF_VENDOR);
 928         }
 929 };
 930
 931 MODULE_INIT(ModuleSSLmbedTLS)