src/security/Session.cc

   1 /*
   2  * Copyright (C) 1996-2018 The Squid Software Foundation and contributors
   3  *
   4  * Squid software is distributed under GPLv2+ license and includes
   5  * contributions from numerous individuals and organizations.
   6  * Please see the COPYING and CONTRIBUTORS files for details.
   7  */
   8
   9 /* DEBUG: section 83    TLS session management */
  10
  11 #include "squid.h"
  12 #include "anyp/PortCfg.h"
  13 #include "base/RunnersRegistry.h"
  14 #include "CachePeer.h"
  15 #include "Debug.h"
  16 #include "fd.h"
  17 #include "fde.h"
  18 #include "ipc/MemMap.h"
  19 #include "security/Session.h"
  20 #include "SquidConfig.h"
  21 #include "ssl/bio.h"
  22
  23 #define SSL_SESSION_ID_SIZE 32
  24 #define SSL_SESSION_MAX_SIZE 10*1024
  25
  26 #if USE_OPENSSL
  27 static Ipc::MemMap *SessionCache = nullptr;
  28 static const char *SessionCacheName = "tls_session_cache";
  29 #endif
  30
  31 #if USE_OPENSSL || USE_GNUTLS
  32 static int
  33 tls_read_method(int fd, char *buf, int len)
  34 {
  35     auto session = fd_table[fd].ssl.get();
  36     debugs(83, 3, "started for session=" << (void*)session);
  37
  38 #if DONT_DO_THIS && USE_OPENSSL
  39     if (!SSL_is_init_finished(session)) {
  40         errno = ENOTCONN;
  41         return -1;
  42     }
  43 #endif
  44
  45 #if USE_OPENSSL
  46     int i = SSL_read(session, buf, len);
  47 #elif USE_GNUTLS
  48     int i = gnutls_record_recv(session, buf, len);
  49 #endif
  50
  51     if (i > 0) {
  52         debugs(83, 8, "TLS FD " << fd << " session=" << (void*)session << " " << i << " bytes");
  53         (void)VALGRIND_MAKE_MEM_DEFINED(buf, i);
  54     }
  55
  56 #if USE_OPENSSL
  57     if (i > 0 && SSL_pending(session) > 0) {
  58 #elif USE_GNUTLS
  59     if (i > 0 && gnutls_record_check_pending(session) > 0) {
  60 #endif
  61         debugs(83, 2, "TLS FD " << fd << " is pending");
  62         fd_table[fd].flags.read_pending = true;
  63     } else
  64         fd_table[fd].flags.read_pending = false;
  65
  66     return i;
  67 }
  68
  69 static int
  70 tls_write_method(int fd, const char *buf, int len)
  71 {
  72     auto session = fd_table[fd].ssl.get();
  73     debugs(83, 3, "started for session=" << (void*)session);
  74
  75 #if USE_OPENSSL
  76     if (!SSL_is_init_finished(session)) {
  77         errno = ENOTCONN;
  78         return -1;
  79     }
  80 #endif
  81
  82 #if USE_OPENSSL
  83     int i = SSL_write(session, buf, len);
  84 #elif USE_GNUTLS
  85     int i = gnutls_record_send(session, buf, len);
  86 #endif
  87
  88     if (i > 0) {
  89         debugs(83, 8, "TLS FD " << fd << " session=" << (void*)session << " " << i << " bytes");
  90     }
  91     return i;
  92 }
  93 #endif
  94
  95 #if USE_OPENSSL
  96 Security::SessionPointer
  97 Security::NewSessionObject(const Security::ContextPointer &ctx)
  98 {
  99     Security::SessionPointer session(SSL_new(ctx.get()), [](SSL *p) {
 100         debugs(83, 5, "SSL_free session=" << (void*)p);
 101         SSL_free(p);
 102     });
 103     debugs(83, 5, "SSL_new session=" << (void*)session.get());
 104     return session;
 105 }
 106 #endif
 107
 108 static bool
 109 CreateSession(const Security::ContextPointer &ctx, const Comm::ConnectionPointer &conn, Security::Io::Type type, const char *squidCtx)
 110 {
 111     if (!Comm::IsConnOpen(conn)) {
 112         debugs(83, DBG_IMPORTANT, "Gone connection");
 113         return false;
 114     }
 115
 116 #if USE_OPENSSL || USE_GNUTLS
 117
 118     const char *errAction = "with no TLS/SSL library";
 119     int errCode = 0;
 120 #if USE_OPENSSL
 121     Security::SessionPointer session(Security::NewSessionObject(ctx));
 122     if (!session) {
 123         errCode = ERR_get_error();
 124         errAction = "failed to allocate handle";
 125     }
 126 #elif USE_GNUTLS
 127     gnutls_session_t tmp;
 128     errCode = gnutls_init(&tmp, static_cast<unsigned int>(type) | GNUTLS_NONBLOCK);
 129     Security::SessionPointer session(tmp, [](gnutls_session_t p) {
 130         debugs(83, 5, "gnutls_deinit session=" << (void*)p);
 131         gnutls_deinit(p);
 132     });
 133     debugs(83, 5, "gnutls_init " << (type == Security::Io::BIO_TO_SERVER ? "client" : "server" )<< " session=" << (void*)session.get());
 134     if (errCode != GNUTLS_E_SUCCESS) {
 135         session.reset();
 136         errAction = "failed to initialize session";
 137     }
 138 #endif
 139
 140     if (session) {
 141         const int fd = conn->fd;
 142
 143 #if USE_OPENSSL
 144         // without BIO, we would call SSL_set_fd(ssl.get(), fd) instead
 145         if (BIO *bio = Ssl::Bio::Create(fd, type)) {
 146             Ssl::Bio::Link(session.get(), bio); // cannot fail
 147 #elif USE_GNUTLS
 148         errCode = gnutls_credentials_set(session.get(), GNUTLS_CRD_CERTIFICATE, ctx.get());
 149         if (errCode == GNUTLS_E_SUCCESS) {
 150
 151             if (auto *peer = conn->getPeer())
 152                 peer->secure.updateSessionOptions(session);
 153             else
 154                 Security::ProxyOutgoingConfig.updateSessionOptions(session);
 155
 156             // NP: GnuTLS does not yet support the BIO operations
 157             //     this does the equivalent of SSL_set_fd() for now.
 158             gnutls_transport_set_int(session.get(), fd);
 159             gnutls_handshake_set_timeout(session.get(), GNUTLS_DEFAULT_HANDSHAKE_TIMEOUT);
 160 #endif
 161
 162             debugs(83, 5, "link FD " << fd << " to TLS session=" << (void*)session.get());
 163             fd_table[fd].ssl = session;
 164             fd_table[fd].read_method = &tls_read_method;
 165             fd_table[fd].write_method = &tls_write_method;
 166             fd_note(fd, squidCtx);
 167             return true;
 168         }
 169
 170 #if USE_OPENSSL
 171         errCode = ERR_get_error();
 172         errAction = "failed to initialize I/O";
 173 #elif USE_GNUTLS
 174         errAction = "failed to assign credentials";
 175 #endif
 176     }
 177
 178     debugs(83, DBG_IMPORTANT, "ERROR: " << squidCtx << ' ' << errAction <<
 179            ": " << (errCode != 0 ? Security::ErrorString(errCode) : ""));
 180 #endif
 181     return false;
 182 }
 183
 184 bool
 185 Security::CreateClientSession(const Security::ContextPointer &ctx, const Comm::ConnectionPointer &c, const char *squidCtx)
 186 {
 187     return CreateSession(ctx, c, Security::Io::BIO_TO_SERVER, squidCtx);
 188 }
 189
 190 bool
 191 Security::CreateServerSession(const Security::ContextPointer &ctx, const Comm::ConnectionPointer &c, const char *squidCtx)
 192 {
 193     return CreateSession(ctx, c, Security::Io::BIO_TO_CLIENT, squidCtx);
 194 }
 195
 196 void
 197 Security::SessionSendGoodbye(const Security::SessionPointer &s)
 198 {
 199     debugs(83, 5, "session=" << (void*)s.get());
 200     if (s) {
 201 #if USE_OPENSSL
 202         SSL_shutdown(s.get());
 203 #elif USE_GNUTLS
 204         gnutls_bye(s.get(), GNUTLS_SHUT_RDWR);
 205 #endif
 206     }
 207 }
 208
 209 bool
 210 Security::SessionIsResumed(const Security::SessionPointer &s)
 211 {
 212     bool result = false;
 213 #if USE_OPENSSL
 214     result = SSL_session_reused(s.get()) == 1;
 215 #elif USE_GNUTLS
 216     result = gnutls_session_is_resumed(s.get()) != 0;
 217 #endif
 218     debugs(83, 7, "session=" << (void*)s.get() << ", query? answer: " << (result ? 'T' : 'F') );
 219     return result;
 220 }
 221
 222 void
 223 Security::MaybeGetSessionResumeData(const Security::SessionPointer &s, Security::SessionStatePointer &data)
 224 {
 225     if (!SessionIsResumed(s)) {
 226 #if USE_OPENSSL
 227         // nil is valid for SSL_get1_session(), it cannot fail.
 228         data.reset(SSL_get1_session(s.get()));
 229 #elif USE_GNUTLS
 230         gnutls_datum_t *tmp = nullptr;
 231         const auto x = gnutls_session_get_data2(s.get(), tmp);
 232         if (x != GNUTLS_E_SUCCESS) {
 233             debugs(83, 3, "session=" << (void*)s.get() << " error: " << Security::ErrorString(x));
 234         }
 235         data.reset(tmp);
 236 #endif
 237         debugs(83, 5, "session=" << (void*)s.get() << " data=" << (void*)data.get());
 238     } else {
 239         debugs(83, 5, "session=" << (void*)s.get() << " data=" << (void*)data.get() << ", do nothing.");
 240     }
 241 }
 242
 243 void
 244 Security::SetSessionResumeData(const Security::SessionPointer &s, const Security::SessionStatePointer &data)
 245 {
 246     if (data) {
 247 #if USE_OPENSSL
 248         if (!SSL_set_session(s.get(), data.get())) {
 249             const auto ssl_error = ERR_get_error();
 250             debugs(83, 3, "session=" << (void*)s.get() << " data=" << (void*)data.get() <<
 251                    " resume error: " << Security::ErrorString(ssl_error));
 252         }
 253 #elif USE_GNUTLS
 254         const auto x = gnutls_session_set_data(s.get(), data->data, data->size);
 255         if (x != GNUTLS_E_SUCCESS) {
 256             debugs(83, 3, "session=" << (void*)s.get() << " data=" << (void*)data.get() <<
 257                    " resume error: " << Security::ErrorString(x));
 258         }
 259 #else
 260         // critical because, how did it get here?
 261         debugs(83, DBG_CRITICAL, "no TLS library. session=" << (void*)s.get() << " data=" << (void*)data.get());
 262 #endif
 263         debugs(83, 5, "session=" << (void*)s.get() << " data=" << (void*)data.get());
 264     } else {
 265         debugs(83, 5, "session=" << (void*)s.get() << " no resume data");
 266     }
 267 }
 268
 269 static bool
 270 isTlsServer()
 271 {
 272     for (AnyP::PortCfgPointer s = HttpPortList; s != nullptr; s = s->next) {
 273         if (s->secure.encryptTransport)
 274             return true;
 275         if (s->flags.tunnelSslBumping)
 276             return true;
 277     }
 278
 279     return false;
 280 }
 281
 282 #if USE_OPENSSL
 283 static int
 284 store_session_cb(SSL *ssl, SSL_SESSION *session)
 285 {
 286     if (!SessionCache)
 287         return 0;
 288
 289     debugs(83, 5, "Request to store SSL_SESSION");
 290
 291     SSL_SESSION_set_timeout(session, Config.SSL.session_ttl);
 292
 293 #if HAVE_LIBSSL_SSL_SESSION_GET_ID
 294     unsigned int idlen;
 295     const unsigned char *id = SSL_SESSION_get_id(session, &idlen);
 296 #else
 297     unsigned char *id = session->session_id;
 298     unsigned int idlen = session->session_id_length;
 299 #endif
 300     // XXX: the other calls [to openForReading()] do not copy the sessionId to a char buffer, does this really have to?
 301     unsigned char key[MEMMAP_SLOT_KEY_SIZE];
 302     // Session ids are of size 32bytes. They should always fit to a
 303     // MemMap::Slot::key
 304     assert(idlen <= MEMMAP_SLOT_KEY_SIZE);
 305     memset(key, 0, sizeof(key));
 306     memcpy(key, id, idlen);
 307     int pos;
 308     if (auto slotW = SessionCache->openForWriting(static_cast<const cache_key*>(key), pos)) {
 309         int lenRequired = i2d_SSL_SESSION(session, nullptr);
 310         if (lenRequired <  MEMMAP_SLOT_DATA_SIZE) {
 311             unsigned char *p = static_cast<unsigned char *>(slotW->p);
 312             lenRequired = i2d_SSL_SESSION(session, &p);
 313             slotW->set(key, nullptr, lenRequired, squid_curtime + Config.SSL.session_ttl);
 314         }
 315         SessionCache->closeForWriting(pos);
 316         debugs(83, 5, "wrote an SSL_SESSION entry of size " << lenRequired << " at pos " << pos);
 317     }
 318     return 0;
 319 }
 320
 321 static void
 322 remove_session_cb(SSL_CTX *, SSL_SESSION *sessionID)
 323 {
 324     if (!SessionCache)
 325         return;
 326
 327     debugs(83, 5, "Request to remove corrupted or not valid SSL_SESSION");
 328     int pos;
 329     if (SessionCache->openForReading(reinterpret_cast<const cache_key*>(sessionID), pos)) {
 330         SessionCache->closeForReading(pos);
 331         // TODO:
 332         // What if we are not able to remove the session?
 333         // Maybe schedule a job to remove it later?
 334         // For now we just have an invalid entry in cache until will be expired
 335         // The OpenSSL library will reject it when we try to use it
 336         SessionCache->free(pos);
 337     }
 338 }
 339
 340 static SSL_SESSION *
 341 #if SQUID_USE_CONST_SSL_SESSION_CBID
 342 get_session_cb(SSL *, const unsigned char *sessionID, int len, int *copy)
 343 #else
 344 get_session_cb(SSL *, unsigned char *sessionID, int len, int *copy)
 345 #endif
 346 {
 347     if (!SessionCache)
 348         return nullptr;
 349
 350     const unsigned int *p = reinterpret_cast<const unsigned int *>(sessionID);
 351     debugs(83, 5, "Request to search for SSL_SESSION of len: " <<
 352            len << p[0] << ":" << p[1]);
 353
 354     SSL_SESSION *session = nullptr;
 355     int pos;
 356     if (const auto slot = SessionCache->openForReading(static_cast<const cache_key*>(sessionID), pos)) {
 357         if (slot->expire > squid_curtime) {
 358             const unsigned char *ptr = slot->p;
 359             session = d2i_SSL_SESSION(nullptr, &ptr, slot->pSize);
 360             debugs(83, 5, "SSL_SESSION retrieved from cache at pos " << pos);
 361         } else
 362             debugs(83, 5, "SSL_SESSION in cache expired");
 363         SessionCache->closeForReading(pos);
 364     }
 365
 366     if (!session)
 367         debugs(83, 5, "Failed to retrieve SSL_SESSION from cache");
 368
 369     // With the parameter copy the callback can require the SSL engine
 370     // to increment the reference count of the SSL_SESSION object, Normally
 371     // the reference count is not incremented and therefore the session must
 372     // not be explicitly freed with SSL_SESSION_free(3).
 373     *copy = 0;
 374     return session;
 375 }
 376
 377 void
 378 Security::SetSessionCacheCallbacks(Security::ContextPointer &ctx)
 379 {
 380     if (SessionCache) {
 381         SSL_CTX_set_session_cache_mode(ctx.get(), SSL_SESS_CACHE_SERVER|SSL_SESS_CACHE_NO_INTERNAL);
 382         SSL_CTX_sess_set_new_cb(ctx.get(), store_session_cb);
 383         SSL_CTX_sess_set_remove_cb(ctx.get(), remove_session_cb);
 384         SSL_CTX_sess_set_get_cb(ctx.get(), get_session_cb);
 385     }
 386 }
 387 #endif /* USE_OPENSSL */
 388
 389 void
 390 initializeSessionCache()
 391 {
 392 #if USE_OPENSSL
 393     // Check if the MemMap keys and data are enough big to hold
 394     // session ids and session data
 395     assert(SSL_SESSION_ID_SIZE >= MEMMAP_SLOT_KEY_SIZE);
 396     assert(SSL_SESSION_MAX_SIZE >= MEMMAP_SLOT_DATA_SIZE);
 397
 398     int configuredItems = ::Config.SSL.sessionCacheSize / sizeof(Ipc::MemMap::Slot);
 399     if (IamWorkerProcess() && configuredItems)
 400         SessionCache = new Ipc::MemMap(SessionCacheName);
 401     else {
 402         SessionCache = nullptr;
 403         return;
 404     }
 405
 406     for (AnyP::PortCfgPointer s = HttpPortList; s != nullptr; s = s->next) {
 407         if (s->secure.staticContext)
 408             Security::SetSessionCacheCallbacks(s->secure.staticContext);
 409     }
 410 #endif
 411 }
 412
 413 /// initializes shared memory segments used by MemStore
 414 class SharedSessionCacheRr: public Ipc::Mem::RegisteredRunner
 415 {
 416 public:
 417     /* RegisteredRunner API */
 418     SharedSessionCacheRr(): owner(nullptr) {}
 419     virtual void useConfig();
 420     virtual ~SharedSessionCacheRr();
 421
 422 protected:
 423     virtual void create();
 424
 425 private:
 426     Ipc::MemMap::Owner *owner;
 427 };
 428
 429 RunnerRegistrationEntry(SharedSessionCacheRr);
 430
 431 void
 432 SharedSessionCacheRr::useConfig()
 433 {
 434 #if USE_OPENSSL
 435     if (SessionCache || !isTlsServer()) // no need to configure SSL_SESSION* cache.
 436         return;
 437
 438     Ipc::Mem::RegisteredRunner::useConfig();
 439     initializeSessionCache();
 440 #endif
 441 }
 442
 443 void
 444 SharedSessionCacheRr::create()
 445 {
 446     if (!isTlsServer()) // no need to configure SSL_SESSION* cache.
 447         return;
 448
 449 #if USE_OPENSSL
 450     if (int items = Config.SSL.sessionCacheSize / sizeof(Ipc::MemMap::Slot))
 451         owner = Ipc::MemMap::Init(SessionCacheName, items);
 452 #endif
 453 }
 454
 455 SharedSessionCacheRr::~SharedSessionCacheRr()
 456 {
 457     // XXX: Enable after testing to reduce at-exit memory "leaks".
 458     // delete SessionCache;
 459
 460     delete owner;
 461 }
 462