granicus.if.org Git - postgresql/blob - src/backend/libpq/be-secure.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * be-secure.c
   4  *        functions related to setting up a secure connection to the frontend.
   5  *        Secure connections are expected to provide confidentiality,
   6  *        message integrity and endpoint authentication.
   7  *
   8  *
   9  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
  10  * Portions Copyright (c) 1994, Regents of the University of California
  11  *
  12  *
  13  * IDENTIFICATION
  14  *        $PostgreSQL: pgsql/src/backend/libpq/be-secure.c,v 1.61 2006/01/11 08:43:12 neilc Exp $
  15  *
  16  *        Since the server static private key ($DataDir/server.key)
  17  *        will normally be stored unencrypted so that the database
  18  *        backend can restart automatically, it is important that
  19  *        we select an algorithm that continues to provide confidentiality
  20  *        even if the attacker has the server's private key.  Empheral
  21  *        DH (EDH) keys provide this, and in fact provide Perfect Forward
  22  *        Secrecy (PFS) except for situations where the session can
  23  *        be hijacked during a periodic handshake/renegotiation.
  24  *        Even that backdoor can be closed if client certificates
  25  *        are used (since the imposter will be unable to successfully
  26  *        complete renegotiation).
  27  *
  28  *        N.B., the static private key should still be protected to
  29  *        the largest extent possible, to minimize the risk of
  30  *        impersonations.
  31  *
  32  *        Another benefit of EDH is that it allows the backend and
  33  *        clients to use DSA keys.      DSA keys can only provide digital
  34  *        signatures, not encryption, and are often acceptable in
  35  *        jurisdictions where RSA keys are unacceptable.
  36  *
  37  *        The downside to EDH is that it makes it impossible to
  38  *        use ssldump(1) if there's a problem establishing an SSL
  39  *        session.      In this case you'll need to temporarily disable
  40  *        EDH by commenting out the callback.
  41  *
  42  *        ...
  43  *
  44  *        Because the risk of cryptanalysis increases as large
  45  *        amounts of data are sent with the same session key, the
  46  *        session keys are periodically renegotiated.
  47  *
  48  * PATCH LEVEL
  49  *        milestone 1: fix basic coding errors
  50  *        [*] existing SSL code pulled out of existing files.
  51  *        [*] SSL_get_error() after SSL_read() and SSL_write(),
  52  *                SSL_shutdown(), default to TLSv1.
  53  *
  54  *        milestone 2: provide endpoint authentication (server)
  55  *        [*] client verifies server cert
  56  *        [*] client verifies server hostname
  57  *
  58  *        milestone 3: improve confidentially, support perfect forward secrecy
  59  *        [ ] use 'random' file, read from '/dev/urandom?'
  60  *        [*] emphermal DH keys, default values
  61  *        [*] periodic renegotiation
  62  *        [*] private key permissions
  63  *
  64  *        milestone 4: provide endpoint authentication (client)
  65  *        [*] server verifies client certificates
  66  *
  67  *        milestone 5: provide informational callbacks
  68  *        [*] provide informational callbacks
  69  *
  70  *        other changes
  71  *        [ ] tcp-wrappers
  72  *        [ ] more informative psql
  73  *
  74  *-------------------------------------------------------------------------
  75  */
  76
  77 #include "postgres.h"
  78
  79 #include <sys/stat.h>
  80 #include <signal.h>
  81 #include <fcntl.h>
  82 #include <ctype.h>
  83 #include <sys/socket.h>
  84 #include <unistd.h>
  85 #include <netdb.h>
  86 #include <netinet/in.h>
  87 #ifdef HAVE_NETINET_TCP_H
  88 #include <netinet/tcp.h>
  89 #include <arpa/inet.h>
  90 #endif
  91
  92 #ifdef USE_SSL
  93 #include <openssl/ssl.h>
  94 #include <openssl/dh.h>
  95 #endif
  96
  97 #include "libpq/libpq.h"
  98 #include "miscadmin.h"
  99 #include "tcop/tcopprot.h"
 100
 101
 102 #ifdef USE_SSL
 103
 104 #define ROOT_CERT_FILE                  "root.crt"
 105 #define SERVER_CERT_FILE                "server.crt"
 106 #define SERVER_PRIVATE_KEY_FILE "server.key"
 107
 108 static DH  *load_dh_file(int keylength);
 109 static DH  *load_dh_buffer(const char *, size_t);
 110 static DH  *tmp_dh_cb(SSL *s, int is_export, int keylength);
 111 static int      verify_cb(int, X509_STORE_CTX *);
 112 static void info_cb(const SSL *ssl, int type, int args);
 113 static int      initialize_SSL(void);
 114 static void destroy_SSL(void);
 115 static int      open_server_SSL(Port *);
 116 static void close_SSL(Port *);
 117 static const char *SSLerrmessage(void);
 118 #endif
 119
 120 #ifdef USE_SSL
 121 /*
 122  *      How much data can be sent across a secure connection
 123  *      (total in both directions) before we require renegotiation.
 124  */
 125 #define RENEGOTIATION_LIMIT (512 * 1024 * 1024)
 126
 127 static SSL_CTX *SSL_context = NULL;
 128 #endif
 129
 130 /* ------------------------------------------------------------ */
 131 /*                                               Hardcoded values                                               */
 132 /* ------------------------------------------------------------ */
 133
 134 /*
 135  *      Hardcoded DH parameters, used in empheral DH keying.
 136  *      As discussed above, EDH protects the confidentiality of
 137  *      sessions even if the static private key is compromised,
 138  *      so we are *highly* motivated to ensure that we can use
 139  *      EDH even if the DBA... or an attacker... deletes the
 140  *      $DataDir/dh*.pem files.
 141  *
 142  *      We could refuse SSL connections unless a good DH parameter
 143  *      file exists, but some clients may quietly renegotiate an
 144  *      unsecured connection without fully informing the user.
 145  *      Very uncool.
 146  *
 147  *      Alternately, the backend could attempt to load these files
 148  *      on startup if SSL is enabled - and refuse to start if any
 149  *      do not exist - but this would tend to piss off DBAs.
 150  *
 151  *      If you want to create your own hardcoded DH parameters
 152  *      for fun and profit, review "Assigned Number for SKIP
 153  *      Protocols" (http://www.skip-vpn.org/spec/numbers.html)
 154  *      for suggestions.
 155  */
 156 #ifdef USE_SSL
 157
 158 static const char file_dh512[] =
 159 "-----BEGIN DH PARAMETERS-----\n\
 160 MEYCQQD1Kv884bEpQBgRjXyEpwpy1obEAxnIByl6ypUM2Zafq9AKUJsCRtMIPWak\n\
 161 XUGfnHy9iUsiGSa6q6Jew1XpKgVfAgEC\n\
 162 -----END DH PARAMETERS-----\n";
 163
 164 static const char file_dh1024[] =
 165 "-----BEGIN DH PARAMETERS-----\n\
 166 MIGHAoGBAPSI/VhOSdvNILSd5JEHNmszbDgNRR0PfIizHHxbLY7288kjwEPwpVsY\n\
 167 jY67VYy4XTjTNP18F1dDox0YbN4zISy1Kv884bEpQBgRjXyEpwpy1obEAxnIByl6\n\
 168 ypUM2Zafq9AKUJsCRtMIPWakXUGfnHy9iUsiGSa6q6Jew1XpL3jHAgEC\n\
 169 -----END DH PARAMETERS-----\n";
 170
 171 static const char file_dh2048[] =
 172 "-----BEGIN DH PARAMETERS-----\n\
 173 MIIBCAKCAQEA9kJXtwh/CBdyorrWqULzBej5UxE5T7bxbrlLOCDaAadWoxTpj0BV\n\
 174 89AHxstDqZSt90xkhkn4DIO9ZekX1KHTUPj1WV/cdlJPPT2N286Z4VeSWc39uK50\n\
 175 T8X8dryDxUcwYc58yWb/Ffm7/ZFexwGq01uejaClcjrUGvC/RgBYK+X0iP1YTknb\n\
 176 zSC0neSRBzZrM2w4DUUdD3yIsxx8Wy2O9vPJI8BD8KVbGI2Ou1WMuF040zT9fBdX\n\
 177 Q6MdGGzeMyEstSr/POGxKUAYEY18hKcKctaGxAMZyAcpesqVDNmWn6vQClCbAkbT\n\
 178 CD1mpF1Bn5x8vYlLIhkmuquiXsNV6TILOwIBAg==\n\
 179 -----END DH PARAMETERS-----\n";
 180
 181 static const char file_dh4096[] =
 182 "-----BEGIN DH PARAMETERS-----\n\
 183 MIICCAKCAgEA+hRyUsFN4VpJ1O8JLcCo/VWr19k3BCgJ4uk+d+KhehjdRqNDNyOQ\n\
 184 l/MOyQNQfWXPeGKmOmIig6Ev/nm6Nf9Z2B1h3R4hExf+zTiHnvVPeRBhjdQi81rt\n\
 185 Xeoh6TNrSBIKIHfUJWBh3va0TxxjQIs6IZOLeVNRLMqzeylWqMf49HsIXqbcokUS\n\
 186 Vt1BkvLdW48j8PPv5DsKRN3tloTxqDJGo9tKvj1Fuk74A+Xda1kNhB7KFlqMyN98\n\
 187 VETEJ6c7KpfOo30mnK30wqw3S8OtaIR/maYX72tGOno2ehFDkq3pnPtEbD2CScxc\n\
 188 alJC+EL7RPk5c/tgeTvCngvc1KZn92Y//EI7G9tPZtylj2b56sHtMftIoYJ9+ODM\n\
 189 sccD5Piz/rejE3Ome8EOOceUSCYAhXn8b3qvxVI1ddd1pED6FHRhFvLrZxFvBEM9\n\
 190 ERRMp5QqOaHJkM+Dxv8Cj6MqrCbfC4u+ZErxodzuusgDgvZiLF22uxMZbobFWyte\n\
 191 OvOzKGtwcTqO/1wV5gKkzu1ZVswVUQd5Gg8lJicwqRWyyNRczDDoG9jVDxmogKTH\n\
 192 AaqLulO7R8Ifa1SwF2DteSGVtgWEN8gDpN3RBmmPTDngyF2DHb5qmpnznwtFKdTL\n\
 193 KWbuHn491xNO25CQWMtem80uKw+pTnisBRF/454n1Jnhub144YRBoN8CAQI=\n\
 194 -----END DH PARAMETERS-----\n";
 195 #endif
 196
 197 /* ------------------------------------------------------------ */
 198 /*                       Procedures common to all secure sessions                       */
 199 /* ------------------------------------------------------------ */
 200
 201 /*
 202  *      Initialize global context
 203  */
 204 int
 205 secure_initialize(void)
 206 {
 207         int                     r = 0;
 208
 209 #ifdef USE_SSL
 210         r = initialize_SSL();
 211 #endif
 212
 213         return r;
 214 }
 215
 216 /*
 217  *      Destroy global context
 218  */
 219 void
 220 secure_destroy(void)
 221 {
 222 #ifdef USE_SSL
 223         destroy_SSL();
 224 #endif
 225 }
 226
 227 /*
 228  *      Attempt to negotiate secure session.
 229  */
 230 int
 231 secure_open_server(Port *port)
 232 {
 233         int                     r = 0;
 234
 235 #ifdef USE_SSL
 236         r = open_server_SSL(port);
 237 #endif
 238
 239         return r;
 240 }
 241
 242 /*
 243  *      Close secure session.
 244  */
 245 void
 246 secure_close(Port *port)
 247 {
 248 #ifdef USE_SSL
 249         if (port->ssl)
 250                 close_SSL(port);
 251 #endif
 252 }
 253
 254 /*
 255  *      Read data from a secure connection.
 256  */
 257 ssize_t
 258 secure_read(Port *port, void *ptr, size_t len)
 259 {
 260         ssize_t         n;
 261
 262 #ifdef USE_SSL
 263         if (port->ssl)
 264         {
 265                 int                     err;
 266
 267 rloop:
 268                 n = SSL_read(port->ssl, ptr, len);
 269                 err = SSL_get_error(port->ssl, n);
 270                 switch (err)
 271                 {
 272                         case SSL_ERROR_NONE:
 273                                 port->count += n;
 274                                 break;
 275                         case SSL_ERROR_WANT_READ:
 276                         case SSL_ERROR_WANT_WRITE:
 277 #ifdef WIN32
 278                                 pgwin32_waitforsinglesocket(SSL_get_fd(port->ssl),
 279                                                                                         (err == SSL_ERROR_WANT_READ) ?
 280                                                                    FD_READ | FD_CLOSE : FD_WRITE | FD_CLOSE);
 281 #endif
 282                                 goto rloop;
 283                         case SSL_ERROR_SYSCALL:
 284                                 if (n == -1)
 285                                         ereport(COMMERROR,
 286                                                         (errcode_for_socket_access(),
 287                                                          errmsg("SSL SYSCALL error: %m")));
 288                                 else
 289                                 {
 290                                         ereport(COMMERROR,
 291                                                         (errcode(ERRCODE_PROTOCOL_VIOLATION),
 292                                                          errmsg("SSL SYSCALL error: EOF detected")));
 293                                         errno = ECONNRESET;
 294                                         n = -1;
 295                                 }
 296                                 break;
 297                         case SSL_ERROR_SSL:
 298                                 ereport(COMMERROR,
 299                                                 (errcode(ERRCODE_PROTOCOL_VIOLATION),
 300                                                  errmsg("SSL error: %s", SSLerrmessage())));
 301                                 /* fall through */
 302                         case SSL_ERROR_ZERO_RETURN:
 303                                 errno = ECONNRESET;
 304                                 n = -1;
 305                                 break;
 306                         default:
 307                                 ereport(COMMERROR,
 308                                                 (errcode(ERRCODE_PROTOCOL_VIOLATION),
 309                                                  errmsg("unrecognized SSL error code: %d",
 310                                                                 err)));
 311                                 n = -1;
 312                                 break;
 313                 }
 314         }
 315         else
 316 #endif
 317         {
 318                 prepare_for_client_read();
 319
 320                 n = recv(port->sock, ptr, len, 0);
 321
 322                 client_read_ended();
 323         }
 324
 325         return n;
 326 }
 327
 328 /*
 329  *      Write data to a secure connection.
 330  */
 331 ssize_t
 332 secure_write(Port *port, void *ptr, size_t len)
 333 {
 334         ssize_t         n;
 335
 336 #ifdef USE_SSL
 337         if (port->ssl)
 338         {
 339                 int                     err;
 340
 341                 if (port->count > RENEGOTIATION_LIMIT)
 342                 {
 343                         SSL_set_session_id_context(port->ssl, (void *) &SSL_context,
 344                                                                            sizeof(SSL_context));
 345                         if (SSL_renegotiate(port->ssl) <= 0)
 346                                 ereport(COMMERROR,
 347                                                 (errcode(ERRCODE_PROTOCOL_VIOLATION),
 348                                                  errmsg("SSL renegotiation failure")));
 349                         if (SSL_do_handshake(port->ssl) <= 0)
 350                                 ereport(COMMERROR,
 351                                                 (errcode(ERRCODE_PROTOCOL_VIOLATION),
 352                                                  errmsg("SSL renegotiation failure")));
 353                         if (port->ssl->state != SSL_ST_OK)
 354                                 ereport(COMMERROR,
 355                                                 (errcode(ERRCODE_PROTOCOL_VIOLATION),
 356                                                  errmsg("SSL failed to send renegotiation request")));
 357                         port->ssl->state |= SSL_ST_ACCEPT;
 358                         SSL_do_handshake(port->ssl);
 359                         if (port->ssl->state != SSL_ST_OK)
 360                                 ereport(COMMERROR,
 361                                                 (errcode(ERRCODE_PROTOCOL_VIOLATION),
 362                                                  errmsg("SSL renegotiation failure")));
 363                         port->count = 0;
 364                 }
 365
 366 wloop:
 367                 n = SSL_write(port->ssl, ptr, len);
 368                 err = SSL_get_error(port->ssl, n);
 369                 switch (err)
 370                 {
 371                         case SSL_ERROR_NONE:
 372                                 port->count += n;
 373                                 break;
 374                         case SSL_ERROR_WANT_READ:
 375                         case SSL_ERROR_WANT_WRITE:
 376 #ifdef WIN32
 377                                 pgwin32_waitforsinglesocket(SSL_get_fd(port->ssl),
 378                                                                                         (err == SSL_ERROR_WANT_READ) ?
 379                                                                    FD_READ | FD_CLOSE : FD_WRITE | FD_CLOSE);
 380 #endif
 381                                 goto wloop;
 382                         case SSL_ERROR_SYSCALL:
 383                                 if (n == -1)
 384                                         ereport(COMMERROR,
 385                                                         (errcode_for_socket_access(),
 386                                                          errmsg("SSL SYSCALL error: %m")));
 387                                 else
 388                                 {
 389                                         ereport(COMMERROR,
 390                                                         (errcode(ERRCODE_PROTOCOL_VIOLATION),
 391                                                          errmsg("SSL SYSCALL error: EOF detected")));
 392                                         errno = ECONNRESET;
 393                                         n = -1;
 394                                 }
 395                                 break;
 396                         case SSL_ERROR_SSL:
 397                                 ereport(COMMERROR,
 398                                                 (errcode(ERRCODE_PROTOCOL_VIOLATION),
 399                                                  errmsg("SSL error: %s", SSLerrmessage())));
 400                                 /* fall through */
 401                         case SSL_ERROR_ZERO_RETURN:
 402                                 errno = ECONNRESET;
 403                                 n = -1;
 404                                 break;
 405                         default:
 406                                 ereport(COMMERROR,
 407                                                 (errcode(ERRCODE_PROTOCOL_VIOLATION),
 408                                                  errmsg("unrecognized SSL error code: %d",
 409                                                                 err)));
 410                                 n = -1;
 411                                 break;
 412                 }
 413         }
 414         else
 415 #endif
 416                 n = send(port->sock, ptr, len, 0);
 417
 418         return n;
 419 }
 420
 421 /* ------------------------------------------------------------ */
 422 /*                                                SSL specific code                                             */
 423 /* ------------------------------------------------------------ */
 424 #ifdef USE_SSL
 425
 426 /*
 427  * Private substitute BIO: this wraps the SSL library's standard socket BIO
 428  * so that we can enable and disable interrupts just while calling recv().
 429  * We cannot have interrupts occurring while the bulk of openssl runs,
 430  * because it uses malloc() and possibly other non-reentrant libc facilities.
 431  *
 432  * As of openssl 0.9.7, we can use the reasonably clean method of interposing
 433  * a wrapper around the standard socket BIO's sock_read() method.  This relies
 434  * on the fact that sock_read() doesn't call anything non-reentrant, in fact
 435  * not much of anything at all except recv().  If this ever changes we'd
 436  * probably need to duplicate the code of sock_read() in order to push the
 437  * interrupt enable/disable down yet another level.
 438  */
 439
 440 static bool my_bio_initialized = false;
 441 static BIO_METHOD my_bio_methods;
 442 static int      (*std_sock_read) (BIO *h, char *buf, int size);
 443
 444 static int
 445 my_sock_read(BIO *h, char *buf, int size)
 446 {
 447         int                     res;
 448
 449         prepare_for_client_read();
 450
 451         res = std_sock_read(h, buf, size);
 452
 453         client_read_ended();
 454
 455         return res;
 456 }
 457
 458 static BIO_METHOD *
 459 my_BIO_s_socket(void)
 460 {
 461         if (!my_bio_initialized)
 462         {
 463                 memcpy(&my_bio_methods, BIO_s_socket(), sizeof(BIO_METHOD));
 464                 std_sock_read = my_bio_methods.bread;
 465                 my_bio_methods.bread = my_sock_read;
 466                 my_bio_initialized = true;
 467         }
 468         return &my_bio_methods;
 469 }
 470
 471 /* This should exactly match openssl's SSL_set_fd except for using my BIO */
 472 static int
 473 my_SSL_set_fd(SSL *s, int fd)
 474 {
 475         int                     ret = 0;
 476         BIO                *bio = NULL;
 477
 478         bio = BIO_new(my_BIO_s_socket());
 479
 480         if (bio == NULL)
 481         {
 482                 SSLerr(SSL_F_SSL_SET_FD, ERR_R_BUF_LIB);
 483                 goto err;
 484         }
 485         BIO_set_fd(bio, fd, BIO_NOCLOSE);
 486         SSL_set_bio(s, bio, bio);
 487         ret = 1;
 488 err:
 489         return ret;
 490 }
 491
 492 /*
 493  *      Load precomputed DH parameters.
 494  *
 495  *      To prevent "downgrade" attacks, we perform a number of checks
 496  *      to verify that the DBA-generated DH parameters file contains
 497  *      what we expect it to contain.
 498  */
 499 static DH  *
 500 load_dh_file(int keylength)
 501 {
 502         FILE       *fp;
 503         char            fnbuf[MAXPGPATH];
 504         DH                 *dh = NULL;
 505         int                     codes;
 506
 507         /* attempt to open file.  It's not an error if it doesn't exist. */
 508         snprintf(fnbuf, sizeof(fnbuf), "dh%d.pem", keylength);
 509         if ((fp = fopen(fnbuf, "r")) == NULL)
 510                 return NULL;
 511
 512 /*      flock(fileno(fp), LOCK_SH); */
 513         dh = PEM_read_DHparams(fp, NULL, NULL, NULL);
 514 /*      flock(fileno(fp), LOCK_UN); */
 515         fclose(fp);
 516
 517         /* is the prime the correct size? */
 518         if (dh != NULL && 8 * DH_size(dh) < keylength)
 519         {
 520                 elog(LOG, "DH errors (%s): %d bits expected, %d bits found",
 521                          fnbuf, keylength, 8 * DH_size(dh));
 522                 dh = NULL;
 523         }
 524
 525         /* make sure the DH parameters are usable */
 526         if (dh != NULL)
 527         {
 528                 if (DH_check(dh, &codes))
 529                 {
 530                         elog(LOG, "DH_check error (%s): %s", fnbuf, SSLerrmessage());
 531                         return NULL;
 532                 }
 533                 if (codes & DH_CHECK_P_NOT_PRIME)
 534                 {
 535                         elog(LOG, "DH error (%s): p is not prime", fnbuf);
 536                         return NULL;
 537                 }
 538                 if ((codes & DH_NOT_SUITABLE_GENERATOR) &&
 539                         (codes & DH_CHECK_P_NOT_SAFE_PRIME))
 540                 {
 541                         elog(LOG,
 542                                  "DH error (%s): neither suitable generator or safe prime",
 543                                  fnbuf);
 544                         return NULL;
 545                 }
 546         }
 547
 548         return dh;
 549 }
 550
 551 /*
 552  *      Load hardcoded DH parameters.
 553  *
 554  *      To prevent problems if the DH parameters files don't even
 555  *      exist, we can load DH parameters hardcoded into this file.
 556  */
 557 static DH  *
 558 load_dh_buffer(const char *buffer, size_t len)
 559 {
 560         BIO                *bio;
 561         DH                 *dh = NULL;
 562
 563         bio = BIO_new_mem_buf((char *) buffer, len);
 564         if (bio == NULL)
 565                 return NULL;
 566         dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL);
 567         if (dh == NULL)
 568                 ereport(DEBUG2,
 569                                 (errmsg_internal("DH load buffer: %s",
 570                                                                  SSLerrmessage())));
 571         BIO_free(bio);
 572
 573         return dh;
 574 }
 575
 576 /*
 577  *      Generate an empheral DH key.  Because this can take a long
 578  *      time to compute, we can use precomputed parameters of the
 579  *      common key sizes.
 580  *
 581  *      Since few sites will bother to precompute these parameter
 582  *      files, we also provide a fallback to the parameters provided
 583  *      by the OpenSSL project.
 584  *
 585  *      These values can be static (once loaded or computed) since
 586  *      the OpenSSL library can efficiently generate random keys from
 587  *      the information provided.
 588  */
 589 static DH  *
 590 tmp_dh_cb(SSL *s, int is_export, int keylength)
 591 {
 592         DH                 *r = NULL;
 593         static DH  *dh = NULL;
 594         static DH  *dh512 = NULL;
 595         static DH  *dh1024 = NULL;
 596         static DH  *dh2048 = NULL;
 597         static DH  *dh4096 = NULL;
 598
 599         switch (keylength)
 600         {
 601                 case 512:
 602                         if (dh512 == NULL)
 603                                 dh512 = load_dh_file(keylength);
 604                         if (dh512 == NULL)
 605                                 dh512 = load_dh_buffer(file_dh512, sizeof file_dh512);
 606                         r = dh512;
 607                         break;
 608
 609                 case 1024:
 610                         if (dh1024 == NULL)
 611                                 dh1024 = load_dh_file(keylength);
 612                         if (dh1024 == NULL)
 613                                 dh1024 = load_dh_buffer(file_dh1024, sizeof file_dh1024);
 614                         r = dh1024;
 615                         break;
 616
 617                 case 2048:
 618                         if (dh2048 == NULL)
 619                                 dh2048 = load_dh_file(keylength);
 620                         if (dh2048 == NULL)
 621                                 dh2048 = load_dh_buffer(file_dh2048, sizeof file_dh2048);
 622                         r = dh2048;
 623                         break;
 624
 625                 case 4096:
 626                         if (dh4096 == NULL)
 627                                 dh4096 = load_dh_file(keylength);
 628                         if (dh4096 == NULL)
 629                                 dh4096 = load_dh_buffer(file_dh4096, sizeof file_dh4096);
 630                         r = dh4096;
 631                         break;
 632
 633                 default:
 634                         if (dh == NULL)
 635                                 dh = load_dh_file(keylength);
 636                         r = dh;
 637         }
 638
 639         /* this may take a long time, but it may be necessary... */
 640         if (r == NULL || 8 * DH_size(r) < keylength)
 641         {
 642                 ereport(DEBUG2,
 643                                 (errmsg_internal("DH: generating parameters (%d bits)....",
 644                                                                  keylength)));
 645                 r = DH_generate_parameters(keylength, DH_GENERATOR_2, NULL, NULL);
 646         }
 647
 648         return r;
 649 }
 650
 651 /*
 652  *      Certificate verification callback
 653  *
 654  *      This callback allows us to log intermediate problems during
 655  *      verification, but for now we'll see if the final error message
 656  *      contains enough information.
 657  *
 658  *      This callback also allows us to override the default acceptance
 659  *      criteria (e.g., accepting self-signed or expired certs), but
 660  *      for now we accept the default checks.
 661  */
 662 static int
 663 verify_cb(int ok, X509_STORE_CTX *ctx)
 664 {
 665         return ok;
 666 }
 667
 668 /*
 669  *      This callback is used to copy SSL information messages
 670  *      into the PostgreSQL log.
 671  */
 672 static void
 673 info_cb(const SSL *ssl, int type, int args)
 674 {
 675         switch (type)
 676         {
 677                 case SSL_CB_HANDSHAKE_START:
 678                         ereport(DEBUG4,
 679                                         (errmsg_internal("SSL: handshake start")));
 680                         break;
 681                 case SSL_CB_HANDSHAKE_DONE:
 682                         ereport(DEBUG4,
 683                                         (errmsg_internal("SSL: handshake done")));
 684                         break;
 685                 case SSL_CB_ACCEPT_LOOP:
 686                         ereport(DEBUG4,
 687                                         (errmsg_internal("SSL: accept loop")));
 688                         break;
 689                 case SSL_CB_ACCEPT_EXIT:
 690                         ereport(DEBUG4,
 691                                         (errmsg_internal("SSL: accept exit (%d)", args)));
 692                         break;
 693                 case SSL_CB_CONNECT_LOOP:
 694                         ereport(DEBUG4,
 695                                         (errmsg_internal("SSL: connect loop")));
 696                         break;
 697                 case SSL_CB_CONNECT_EXIT:
 698                         ereport(DEBUG4,
 699                                         (errmsg_internal("SSL: connect exit (%d)", args)));
 700                         break;
 701                 case SSL_CB_READ_ALERT:
 702                         ereport(DEBUG4,
 703                                         (errmsg_internal("SSL: read alert (0x%04x)", args)));
 704                         break;
 705                 case SSL_CB_WRITE_ALERT:
 706                         ereport(DEBUG4,
 707                                         (errmsg_internal("SSL: write alert (0x%04x)", args)));
 708                         break;
 709         }
 710 }
 711
 712 /*
 713  *      Initialize global SSL context.
 714  */
 715 static int
 716 initialize_SSL(void)
 717 {
 718         struct stat buf;
 719
 720         if (!SSL_context)
 721         {
 722                 SSL_library_init();
 723                 SSL_load_error_strings();
 724                 SSL_context = SSL_CTX_new(SSLv23_method());
 725                 if (!SSL_context)
 726                         ereport(FATAL,
 727                                         (errmsg("could not create SSL context: %s",
 728                                                         SSLerrmessage())));
 729
 730                 /*
 731                  * Load and verify certificate and private key
 732                  */
 733                 if (!SSL_CTX_use_certificate_file(SSL_context,
 734                                                                                   SERVER_CERT_FILE,
 735                                                                                   SSL_FILETYPE_PEM))
 736                         ereport(FATAL,
 737                                         (errcode(ERRCODE_CONFIG_FILE_ERROR),
 738                                   errmsg("could not load server certificate file \"%s\": %s",
 739                                                  SERVER_CERT_FILE, SSLerrmessage())));
 740
 741                 if (stat(SERVER_PRIVATE_KEY_FILE, &buf) == -1)
 742                         ereport(FATAL,
 743                                         (errcode_for_file_access(),
 744                                          errmsg("could not access private key file \"%s\": %m",
 745                                                         SERVER_PRIVATE_KEY_FILE)));
 746
 747                 /*
 748                  * Require no public access to key file.
 749                  *
 750                  * XXX temporarily suppress check when on Windows, because there may
 751                  * not be proper support for Unix-y file permissions.  Need to think
 752                  * of a reasonable check to apply on Windows.  (See also the data
 753                  * directory permission check in postmaster.c)
 754                  */
 755 #if !defined(WIN32) && !defined(__CYGWIN__)
 756                 if (!S_ISREG(buf.st_mode) || (buf.st_mode & (S_IRWXG | S_IRWXO)) ||
 757                         buf.st_uid != geteuid())
 758                         ereport(FATAL,
 759                                         (errcode(ERRCODE_CONFIG_FILE_ERROR),
 760                                          errmsg("unsafe permissions on private key file \"%s\"",
 761                                                         SERVER_PRIVATE_KEY_FILE),
 762                                          errdetail("File must be owned by the database user and must have no permissions for \"group\" or \"other\".")));
 763 #endif
 764
 765                 if (!SSL_CTX_use_PrivateKey_file(SSL_context,
 766                                                                                  SERVER_PRIVATE_KEY_FILE,
 767                                                                                  SSL_FILETYPE_PEM))
 768                         ereport(FATAL,
 769                                         (errmsg("could not load private key file \"%s\": %s",
 770                                                         SERVER_PRIVATE_KEY_FILE, SSLerrmessage())));
 771
 772                 if (!SSL_CTX_check_private_key(SSL_context))
 773                         ereport(FATAL,
 774                                         (errmsg("check of private key failed: %s",
 775                                                         SSLerrmessage())));
 776         }
 777
 778         /* set up empheral DH keys */
 779         SSL_CTX_set_tmp_dh_callback(SSL_context, tmp_dh_cb);
 780         SSL_CTX_set_options(SSL_context, SSL_OP_SINGLE_DH_USE | SSL_OP_NO_SSLv2);
 781
 782         /* setup the allowed cipher list */
 783         if (SSL_CTX_set_cipher_list(SSL_context, "ALL:!ADH:!LOW:!EXP:!MD5:@STRENGTH") != 1)
 784                 elog(FATAL, "could not set the cipher list (no valid ciphers available)");
 785
 786         /*
 787          * Require and check client certificates only if we have a root.crt file.
 788          */
 789         if (!SSL_CTX_load_verify_locations(SSL_context, ROOT_CERT_FILE, NULL))
 790         {
 791                 /* Not fatal - we do not require client certificates */
 792                 ereport(LOG,
 793                                 (errmsg("could not load root certificate file \"%s\": %s",
 794                                                 ROOT_CERT_FILE, SSLerrmessage()),
 795                                  errdetail("Will not verify client certificates.")));
 796         }
 797         else
 798         {
 799                 SSL_CTX_set_verify(SSL_context,
 800                                                    (SSL_VERIFY_PEER |
 801                                                         SSL_VERIFY_FAIL_IF_NO_PEER_CERT |
 802                                                         SSL_VERIFY_CLIENT_ONCE),
 803                                                    verify_cb);
 804         }
 805
 806         return 0;
 807 }
 808
 809 /*
 810  *      Destroy global SSL context.
 811  */
 812 static void
 813 destroy_SSL(void)
 814 {
 815         if (SSL_context)
 816         {
 817                 SSL_CTX_free(SSL_context);
 818                 SSL_context = NULL;
 819         }
 820 }
 821
 822 /*
 823  *      Attempt to negotiate SSL connection.
 824  */
 825 static int
 826 open_server_SSL(Port *port)
 827 {
 828         int                     r;
 829         int                     err;
 830
 831         Assert(!port->ssl);
 832         Assert(!port->peer);
 833
 834         if (!(port->ssl = SSL_new(SSL_context)))
 835         {
 836                 ereport(COMMERROR,
 837                                 (errcode(ERRCODE_PROTOCOL_VIOLATION),
 838                                  errmsg("could not initialize SSL connection: %s",
 839                                                 SSLerrmessage())));
 840                 close_SSL(port);
 841                 return -1;
 842         }
 843         if (!my_SSL_set_fd(port->ssl, port->sock))
 844         {
 845                 ereport(COMMERROR,
 846                                 (errcode(ERRCODE_PROTOCOL_VIOLATION),
 847                                  errmsg("could not set SSL socket: %s",
 848                                                 SSLerrmessage())));
 849                 close_SSL(port);
 850                 return -1;
 851         }
 852
 853 aloop:
 854         r = SSL_accept(port->ssl);
 855         if (r <= 0)
 856         {
 857                 err = SSL_get_error(port->ssl, r);
 858                 switch (err)
 859                 {
 860                         case SSL_ERROR_WANT_READ:
 861                         case SSL_ERROR_WANT_WRITE:
 862 #ifdef WIN32
 863                                 pgwin32_waitforsinglesocket(SSL_get_fd(port->ssl),
 864                                                                                         (err == SSL_ERROR_WANT_READ) ?
 865                                            FD_READ | FD_CLOSE | FD_ACCEPT : FD_WRITE | FD_CLOSE);
 866 #endif
 867                                 goto aloop;
 868                         case SSL_ERROR_SYSCALL:
 869                                 if (r < 0)
 870                                         ereport(COMMERROR,
 871                                                         (errcode_for_socket_access(),
 872                                                          errmsg("could not accept SSL connection: %m")));
 873                                 else
 874                                         ereport(COMMERROR,
 875                                                         (errcode(ERRCODE_PROTOCOL_VIOLATION),
 876                                         errmsg("could not accept SSL connection: EOF detected")));
 877                                 break;
 878                         case SSL_ERROR_SSL:
 879                                 ereport(COMMERROR,
 880                                                 (errcode(ERRCODE_PROTOCOL_VIOLATION),
 881                                                  errmsg("could not accept SSL connection: %s",
 882                                                                 SSLerrmessage())));
 883                                 break;
 884                         case SSL_ERROR_ZERO_RETURN:
 885                                 ereport(COMMERROR,
 886                                                 (errcode(ERRCODE_PROTOCOL_VIOLATION),
 887                                    errmsg("could not accept SSL connection: EOF detected")));
 888                                 break;
 889                         default:
 890                                 ereport(COMMERROR,
 891                                                 (errcode(ERRCODE_PROTOCOL_VIOLATION),
 892                                                  errmsg("unrecognized SSL error code: %d",
 893                                                                 err)));
 894                                 break;
 895                 }
 896                 close_SSL(port);
 897                 return -1;
 898         }
 899
 900         port->count = 0;
 901
 902         /* get client certificate, if available. */
 903         port->peer = SSL_get_peer_certificate(port->ssl);
 904         if (port->peer == NULL)
 905         {
 906                 strncpy(port->peer_dn, "(anonymous)", sizeof(port->peer_dn));
 907                 strncpy(port->peer_cn, "(anonymous)", sizeof(port->peer_cn));
 908         }
 909         else
 910         {
 911                 X509_NAME_oneline(X509_get_subject_name(port->peer),
 912                                                   port->peer_dn, sizeof(port->peer_dn));
 913                 port->peer_dn[sizeof(port->peer_dn) - 1] = '\0';
 914                 X509_NAME_get_text_by_NID(X509_get_subject_name(port->peer),
 915                                            NID_commonName, port->peer_cn, sizeof(port->peer_cn));
 916                 port->peer_cn[sizeof(port->peer_cn) - 1] = '\0';
 917         }
 918         ereport(DEBUG2,
 919                         (errmsg("SSL connection from \"%s\"", port->peer_cn)));
 920
 921         /* set up debugging/info callback */
 922         SSL_CTX_set_info_callback(SSL_context, info_cb);
 923
 924         return 0;
 925 }
 926
 927 /*
 928  *      Close SSL connection.
 929  */
 930 static void
 931 close_SSL(Port *port)
 932 {
 933         if (port->ssl)
 934         {
 935                 SSL_shutdown(port->ssl);
 936                 SSL_free(port->ssl);
 937                 port->ssl = NULL;
 938         }
 939
 940         if (port->peer)
 941         {
 942                 X509_free(port->peer);
 943                 port->peer = NULL;
 944         }
 945 }
 946
 947 /*
 948  * Obtain reason string for last SSL error
 949  *
 950  * Some caution is needed here since ERR_reason_error_string will
 951  * return NULL if it doesn't recognize the error code.  We don't
 952  * want to return NULL ever.
 953  */
 954 static const char *
 955 SSLerrmessage(void)
 956 {
 957         unsigned long errcode;
 958         const char *errreason;
 959         static char errbuf[32];
 960
 961         errcode = ERR_get_error();
 962         if (errcode == 0)
 963                 return "No SSL error reported";
 964         errreason = ERR_reason_error_string(errcode);
 965         if (errreason != NULL)
 966                 return errreason;
 967         snprintf(errbuf, sizeof(errbuf), "SSL error code %lu", errcode);
 968         return errbuf;
 969 }
 970
 971 #endif   /* USE_SSL */