1 /* $NetBSD: sign.c,v 1.5 2012/06/06 00:33:45 christos Exp $ */ 2 3 /*- 4 * Copyright (c) 2008 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Martin Sch�tte. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the NetBSD 21 * Foundation, Inc. and its contributors. 22 * 4. Neither the name of The NetBSD Foundation nor the names of its 23 * contributors may be used to endorse or promote products derived 24 * from this software without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 27 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 28 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 29 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 30 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 31 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 32 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 33 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 34 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 35 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 36 * POSSIBILITY OF SUCH DAMAGE. 37 */ 38 /* 39 * sign.c 40 * syslog-sign related code for syslogd 41 * 42 * Martin Sch�tte 43 */ 44 /* 45 * Issues with the current internet draft: 46 * 1. The draft is a bit unclear on the input format for the signature, 47 * so this might have to be changed later. Cf. sign_string_sign() 48 * 2. The draft only defines DSA signatures. I hope it will be extended 49 * to DSS, thus allowing DSA, RSA (ANSI X9.31) and ECDSA (ANSI X9.62) 50 * 3. The draft does not define the data format for public keys in CBs. 51 * This implementation sends public keys in DER encoding. 52 * 4. This current implementation uses high-level OpenSSL API. 53 * I am not sure if these completely implement the FIPS/ANSI standards. 54 * Update after WG discussion in August: 55 * 1. check; next draft will be clearer and specify the format as implemented. 56 * 2. check; definitely only DSA in this version. 57 * 3. remains a problem, so far no statement from authors or WG. 58 * 4. check; used EVP_dss1 method implements FIPS. 59 */ 60 /* 61 * Limitations of this implementation: 62 * - cannot use OpenPGP keys, only PKIX or DSA due to OpenSSL capabilities 63 * - only works for correctly formatted messages, because incorrect messages 64 * are reformatted (e.g. if it receives a message with two spaces between 65 * fields it might even be parsed, but the output will have only one space). 66 */ 67 68 #include <sys/cdefs.h> 69 __RCSID("$NetBSD: sign.c,v 1.5 2012/06/06 00:33:45 christos Exp $"); 70 71 #ifndef DISABLE_SIGN 72 #include "syslogd.h" 73 #ifndef DISABLE_TLS 74 #include "tls.h" 75 #endif /* !DISABLE_TLS */ 76 #include "sign.h" 77 #include "extern.h" 78 79 /* 80 * init all SGs for a given algorithm 81 */ 82 bool 83 sign_global_init(struct filed *Files) 84 { 85 DPRINTF((D_CALL|D_SIGN), "sign_global_init()\n"); 86 if (!(GlobalSign.sg == 0 || GlobalSign.sg == 1 87 || GlobalSign.sg == 2 || GlobalSign.sg == 3)) { 88 logerror("sign_init(): invalid SG %d", GlobalSign.sg); 89 return false; 90 } 91 92 if (!sign_get_keys()) 93 return false; 94 95 /* signature algorithm */ 96 /* can probably be merged with the hash algorithm/context but 97 * I leave the optimization for later until the RFC is ready */ 98 GlobalSign.sigctx = EVP_MD_CTX_create(); 99 EVP_MD_CTX_init(GlobalSign.sigctx); 100 101 /* the signature algorithm depends on the type of key */ 102 if (EVP_PKEY_DSA == EVP_PKEY_type(GlobalSign.pubkey->type)) { 103 GlobalSign.sig = EVP_dss1(); 104 GlobalSign.sig_len_b64 = SIGN_B64SIGLEN_DSS; 105 /* this is the place to add non-DSA key types and algorithms 106 } else if (EVP_PKEY_RSA == EVP_PKEY_type(GlobalSign.pubkey->type)) { 107 GlobalSign.sig = EVP_sha1(); 108 GlobalSign.sig_len_b64 = 28; 109 */ 110 } else { 111 logerror("key type not supported for syslog-sign"); 112 return false; 113 } 114 115 assert(GlobalSign.keytype == 'C' || GlobalSign.keytype == 'K'); 116 assert(GlobalSign.pubkey_b64 && GlobalSign.privkey && 117 GlobalSign.pubkey); 118 assert(GlobalSign.privkey->pkey.dsa->priv_key); 119 120 GlobalSign.gbc = 0; 121 STAILQ_INIT(&GlobalSign.SigGroups); 122 123 /* hash algorithm */ 124 OpenSSL_add_all_digests(); 125 GlobalSign.mdctx = EVP_MD_CTX_create(); 126 EVP_MD_CTX_init(GlobalSign.mdctx); 127 128 /* values for SHA-1 */ 129 GlobalSign.md = EVP_dss1(); 130 GlobalSign.md_len_b64 = 28; 131 GlobalSign.ver = "0111"; 132 133 if (!sign_sg_init(Files)) 134 return false; 135 sign_new_reboot_session(); 136 137 DPRINTF(D_SIGN, "length values: SIGN_MAX_SD_LENGTH %d, " 138 "SIGN_MAX_FRAG_LENGTH %d, SIGN_MAX_SB_LENGTH %d, " 139 "SIGN_MAX_HASH_NUM %d\n", SIGN_MAX_SD_LENGTH, 140 SIGN_MAX_FRAG_LENGTH, SIGN_MAX_SB_LENGTH, SIGN_MAX_HASH_NUM); 141 142 /* set just before return, so it indicates initialization */ 143 GlobalSign.rsid = now; 144 return true; 145 } 146 147 /* 148 * get keys for syslog-sign 149 * either from the X.509 certificate used for TLS 150 * or by generating a new one 151 * 152 * sets the global variables 153 * GlobalSign.keytype, GlobalSign.pubkey_b64, 154 * GlobalSign.privkey, and GlobalSign.pubkey 155 */ 156 bool 157 sign_get_keys(void) 158 { 159 EVP_PKEY *pubkey = NULL, *privkey = NULL; 160 unsigned char *der_pubkey = NULL, *ptr_der_pubkey = NULL; 161 char *pubkey_b64 = NULL; 162 int der_len; 163 164 /* try PKIX/TLS key first */ 165 #ifndef DISABLE_TLS 166 SSL *ssl; 167 if (tls_opt.global_TLS_CTX 168 && (ssl = SSL_new(tls_opt.global_TLS_CTX))) { 169 X509 *cert; 170 DPRINTF(D_SIGN, "Try to get keys from TLS X.509 cert...\n"); 171 172 if (!(cert = SSL_get_certificate(ssl))) { 173 logerror("SSL_get_certificate() failed"); 174 FREE_SSL(ssl); 175 return false; 176 } 177 if (!(privkey = SSL_get_privatekey(ssl))) { 178 logerror("SSL_get_privatekey() failed"); 179 FREE_SSL(ssl); 180 return false; 181 } 182 if (!(pubkey = X509_get_pubkey(cert))) { 183 logerror("X509_get_pubkey() failed"); 184 FREE_SSL(ssl); 185 return false; 186 } 187 /* note: 188 * - privkey is just a pointer into SSL_CTX and 189 * must not be changed nor be free()d 190 * - but pubkey has to be freed with EVP_PKEY_free() 191 */ 192 FREE_SSL(ssl); 193 194 if (EVP_PKEY_DSA != EVP_PKEY_type(pubkey->type)) { 195 DPRINTF(D_SIGN, "X.509 cert has no DSA key\n"); 196 EVP_PKEY_free(pubkey); 197 privkey = NULL; 198 pubkey = NULL; 199 } else { 200 DPRINTF(D_SIGN, "Got public and private key " 201 "from X.509 --> use type PKIX\n"); 202 GlobalSign.keytype = 'C'; 203 GlobalSign.privkey = privkey; 204 GlobalSign.pubkey = pubkey; 205 206 /* base64 certificate encoding */ 207 der_len = i2d_X509(cert, NULL); 208 if (!(ptr_der_pubkey = der_pubkey = malloc(der_len)) 209 || !(pubkey_b64 = malloc(der_len*2))) { 210 free(der_pubkey); 211 logerror("malloc() failed"); 212 return false; 213 } 214 if (i2d_X509(cert, &ptr_der_pubkey) <= 0) { 215 logerror("i2d_X509() failed"); 216 return false; 217 } 218 b64_ntop(der_pubkey, der_len, pubkey_b64, der_len*2); 219 free(der_pubkey); 220 /* try to resize memory object as needed */ 221 GlobalSign.pubkey_b64 = realloc(pubkey_b64, 222 strlen(pubkey_b64)+1); 223 if (!GlobalSign.pubkey_b64) 224 GlobalSign.pubkey_b64 = pubkey_b64; 225 } 226 } 227 #endif /* !DISABLE_TLS */ 228 if (!(privkey && pubkey)) { /* PKIX not available --> generate key */ 229 DSA *dsa; 230 231 DPRINTF(D_SIGN, "Unable to get keys from X.509 " 232 "--> use DSA with type 'K'\n"); 233 if (!(privkey = EVP_PKEY_new())) { 234 logerror("EVP_PKEY_new() failed"); 235 return false; 236 } 237 dsa = DSA_generate_parameters(SIGN_GENCERT_BITS, NULL, 0, 238 NULL, NULL, NULL, NULL); 239 if (!DSA_generate_key(dsa)) { 240 logerror("DSA_generate_key() failed"); 241 return false; 242 } 243 if (!EVP_PKEY_assign_DSA(privkey, dsa)) { 244 logerror("EVP_PKEY_assign_DSA() failed"); 245 return false; 246 } 247 GlobalSign.keytype = 'K'; /* public/private keys used */ 248 GlobalSign.privkey = privkey; 249 GlobalSign.pubkey = privkey; 250 251 /* pubkey base64 encoding */ 252 der_len = i2d_DSA_PUBKEY(dsa, NULL); 253 if (!(ptr_der_pubkey = der_pubkey = malloc(der_len)) 254 || !(pubkey_b64 = malloc(der_len*2))) { 255 free(der_pubkey); 256 logerror("malloc() failed"); 257 return false; 258 } 259 if (i2d_DSA_PUBKEY(dsa, &ptr_der_pubkey) <= 0) { 260 logerror("i2d_DSA_PUBKEY() failed"); 261 free(der_pubkey); 262 free(pubkey_b64); 263 return false; 264 } 265 b64_ntop(der_pubkey, der_len, pubkey_b64, der_len*2); 266 free(der_pubkey); 267 /* try to resize memory object as needed */ 268 GlobalSign.pubkey_b64 = realloc(pubkey_b64, 269 strlen(pubkey_b64) + 1); 270 if (!GlobalSign.pubkey_b64) 271 GlobalSign.pubkey_b64 = pubkey_b64; 272 } 273 return true; 274 } 275 276 /* 277 * init SGs 278 */ 279 bool 280 sign_sg_init(struct filed *Files) 281 { 282 struct signature_group_t *sg, *newsg, *last_sg; 283 struct filed_queue *fq; 284 struct string_queue *sqentry, *last_sqentry; 285 struct filed *f; 286 unsigned int i; 287 288 /* note on SG 1 and 2: 289 * it is assumed that redundant signature groups 290 * and especially signature groups without an associated 291 * destination are harmless. 292 * this currently holds true because sign_append_hash() 293 * is called from fprintlog(), so only actually used 294 * signature group get hashes and need memory for them 295 */ 296 /* possible optimization for SGs 1 and 2: 297 * use a struct signature_group_t *newsg[IETF_NUM_PRIVALUES] 298 * for direct group lookup 299 */ 300 301 #define ALLOC_OR_FALSE(x) do { \ 302 if(!((x) = calloc(1, sizeof(*(x))))) { \ 303 logerror("Unable to allocate memory"); \ 304 return false; \ 305 } \ 306 } while (/*CONSTCOND*/0) 307 308 #define ALLOC_SG(x) do { \ 309 ALLOC_OR_FALSE(x); \ 310 (x)->last_msg_num = 1; /* cf. section 4.2.5 */ \ 311 STAILQ_INIT(&(x)->hashes); \ 312 STAILQ_INIT(&(x)->files); \ 313 } while (/*CONSTCOND*/0) 314 315 /* alloc(fq) and add to SGs file queue */ 316 #define ASSIGN_FQ() do { \ 317 ALLOC_OR_FALSE(fq); \ 318 fq->f = f; \ 319 f->f_sg = newsg; \ 320 DPRINTF(D_SIGN, "SG@%p <--> f@%p\n", newsg, f); \ 321 STAILQ_INSERT_TAIL(&newsg->files, fq, entries); \ 322 } while (/*CONSTCOND*/0) 323 324 switch (GlobalSign.sg) { 325 case 0: 326 /* one SG, linked to all files */ 327 ALLOC_SG(newsg); 328 newsg->spri = 0; 329 for (f = Files; f; f = f->f_next) 330 ASSIGN_FQ(); 331 STAILQ_INSERT_TAIL(&GlobalSign.SigGroups, 332 newsg, entries); 333 break; 334 case 1: 335 /* every PRI gets one SG */ 336 for (i = 0; i < IETF_NUM_PRIVALUES; i++) { 337 int fac, prilev; 338 fac = LOG_FAC(i); 339 prilev = LOG_PRI(i); 340 ALLOC_SG(newsg); 341 newsg->spri = i; 342 343 /* now find all destinations associated with this SG */ 344 for (f = Files; f; f = f->f_next) 345 /* check priorities */ 346 if (MATCH_PRI(f, fac, prilev)) 347 ASSIGN_FQ(); 348 STAILQ_INSERT_TAIL(&GlobalSign.SigGroups, 349 newsg, entries); 350 } 351 break; 352 case 2: 353 /* PRI ranges get one SG, boundaries given by the 354 * SPRI, indicating the largest PRI in the SG 355 * 356 * either GlobalSign.sig2_delims has a list of 357 * user configured delimiters, or we use a default 358 * and set up one SG per facility 359 */ 360 if (STAILQ_EMPTY(&GlobalSign.sig2_delims)) { 361 DPRINTF(D_SIGN, "sign_sg_init(): set default " 362 "values for SG 2\n"); 363 for (i = 0; i < (IETF_NUM_PRIVALUES>>3); i++) { 364 ALLOC_OR_FALSE(sqentry); 365 sqentry->data = NULL; 366 sqentry->key = (i<<3); 367 STAILQ_INSERT_TAIL(&GlobalSign.sig2_delims, 368 sqentry, entries); 369 } 370 } 371 assert(!STAILQ_EMPTY(&GlobalSign.sig2_delims)); 372 373 /* add one more group at the end */ 374 last_sqentry = STAILQ_LAST(&GlobalSign.sig2_delims, 375 string_queue, entries); 376 if (last_sqentry->key < IETF_NUM_PRIVALUES) { 377 ALLOC_OR_FALSE(sqentry); 378 sqentry->data = NULL; 379 sqentry->key = IETF_NUM_PRIVALUES-1; 380 STAILQ_INSERT_TAIL(&GlobalSign.sig2_delims, 381 sqentry, entries); 382 } 383 384 STAILQ_FOREACH(sqentry, &GlobalSign.sig2_delims, entries) { 385 unsigned int min_pri = 0; 386 ALLOC_SG(newsg); 387 newsg->spri = sqentry->key; 388 389 /* check _all_ priorities in SG */ 390 last_sg = STAILQ_LAST(&GlobalSign.SigGroups, 391 signature_group_t, entries); 392 if (last_sg) 393 min_pri = last_sg->spri + 1; 394 395 DPRINTF(D_SIGN, "sign_sg_init(): add SG@%p: SG=\"2\"," 396 " SPRI=\"%d\" -- for msgs with " 397 "%d <= pri <= %d\n", 398 newsg, newsg->spri, min_pri, newsg->spri); 399 /* now find all destinations associated with this SG */ 400 for (f = Files; f; f = f->f_next) { 401 bool match = false; 402 for (i = min_pri; i <= newsg->spri; i++) { 403 int fac, prilev; 404 fac = LOG_FAC(i); 405 prilev = LOG_PRI(i); 406 if (MATCH_PRI(f, fac, prilev)) { 407 match = true; 408 break; 409 } 410 } 411 if (match) 412 ASSIGN_FQ(); 413 } 414 STAILQ_INSERT_TAIL(&GlobalSign.SigGroups, 415 newsg, entries); 416 } 417 break; 418 case 3: 419 /* every file (with flag) gets one SG */ 420 for (f = Files; f; f = f->f_next) { 421 if (!(f->f_flags & FFLAG_SIGN)) { 422 f->f_sg = NULL; 423 continue; 424 } 425 ALLOC_SG(newsg); 426 newsg->spri = f->f_file; /* not needed but shows SGs */ 427 ASSIGN_FQ(); 428 STAILQ_INSERT_TAIL(&GlobalSign.SigGroups, 429 newsg, entries); 430 } 431 break; 432 } 433 DPRINTF((D_PARSE|D_SIGN), "sign_sg_init() set up these " 434 "Signature Groups:\n"); 435 STAILQ_FOREACH(sg, &GlobalSign.SigGroups, entries) { 436 DPRINTF((D_PARSE|D_SIGN), "SG@%p with SG=\"%d\", SPRI=\"%d\"," 437 " associated files:\n", sg, GlobalSign.sg, sg->spri); 438 STAILQ_FOREACH(fq, &sg->files, entries) { 439 DPRINTF((D_PARSE|D_SIGN), " f@%p with type %d\n", 440 fq->f, fq->f->f_type); 441 } 442 } 443 return true; 444 } 445 446 /* 447 * free all SGs for a given algorithm 448 */ 449 void 450 sign_global_free(void) 451 { 452 struct signature_group_t *sg, *tmp_sg; 453 struct filed_queue *fq, *tmp_fq; 454 455 DPRINTF((D_CALL|D_SIGN), "sign_global_free()\n"); 456 STAILQ_FOREACH_SAFE(sg, &GlobalSign.SigGroups, entries, tmp_sg) { 457 if (!STAILQ_EMPTY(&sg->hashes)) { 458 /* send CB and SB twice to get minimal redundancy 459 * for the last few message hashes */ 460 sign_send_certificate_block(sg); 461 sign_send_certificate_block(sg); 462 sign_send_signature_block(sg, true); 463 sign_send_signature_block(sg, true); 464 sign_free_hashes(sg); 465 } 466 fq = STAILQ_FIRST(&sg->files); 467 while (fq != NULL) { 468 tmp_fq = STAILQ_NEXT(fq, entries); 469 free(fq); 470 fq = tmp_fq; 471 } 472 STAILQ_REMOVE(&GlobalSign.SigGroups, 473 sg, signature_group_t, entries); 474 free(sg); 475 } 476 sign_free_string_queue(&GlobalSign.sig2_delims); 477 478 if (GlobalSign.privkey) { 479 GlobalSign.privkey = NULL; 480 } 481 if (GlobalSign.pubkey) { 482 EVP_PKEY_free(GlobalSign.pubkey); 483 GlobalSign.pubkey = NULL; 484 } 485 if(GlobalSign.mdctx) { 486 EVP_MD_CTX_destroy(GlobalSign.mdctx); 487 GlobalSign.mdctx = NULL; 488 } 489 if(GlobalSign.sigctx) { 490 EVP_MD_CTX_destroy(GlobalSign.sigctx); 491 GlobalSign.sigctx = NULL; 492 } 493 FREEPTR(GlobalSign.pubkey_b64); 494 } 495 496 /* 497 * create and send certificate block 498 */ 499 bool 500 sign_send_certificate_block(struct signature_group_t *sg) 501 { 502 struct filed_queue *fq; 503 struct buf_msg *buffer; 504 char *tstamp; 505 char payload[SIGN_MAX_PAYLOAD_LENGTH]; 506 char sd[SIGN_MAX_SD_LENGTH]; 507 size_t payload_len, sd_len, fragment_len; 508 size_t payload_index = 0; 509 510 /* do nothing if CBs already sent or if there was no message in SG */ 511 if (!sg->resendcount 512 || ((sg->resendcount == SIGN_RESENDCOUNT_CERTBLOCK) 513 && STAILQ_EMPTY(&sg->hashes))) 514 return false; 515 516 DPRINTF((D_CALL|D_SIGN), "sign_send_certificate_block(%p)\n", sg); 517 tstamp = make_timestamp(NULL, true); 518 519 payload_len = snprintf(payload, sizeof(payload), "%s %c %s", tstamp, 520 GlobalSign.keytype, GlobalSign.pubkey_b64); 521 if (payload_len >= sizeof(payload)) { 522 DPRINTF(D_SIGN, "Buffer too small for syslog-sign setup\n"); 523 return false; 524 } 525 526 while (payload_index < payload_len) { 527 if (payload_len - payload_index <= SIGN_MAX_FRAG_LENGTH) 528 fragment_len = payload_len - payload_index; 529 else 530 fragment_len = SIGN_MAX_FRAG_LENGTH; 531 532 /* format SD */ 533 sd_len = snprintf(sd, sizeof(sd), "[ssign-cert " 534 "VER=\"%s\" RSID=\"%" PRIuFAST64 "\" SG=\"%d\" " 535 "SPRI=\"%d\" TBPL=\"%zu\" INDEX=\"%zu\" " 536 "FLEN=\"%zu\" FRAG=\"%.*s\" " 537 "SIGN=\"\"]", 538 GlobalSign.ver, GlobalSign.rsid, GlobalSign.sg, 539 sg->spri, payload_len, payload_index+1, 540 fragment_len, (int)fragment_len, 541 &payload[payload_index]); 542 assert(sd_len < sizeof(sd)); 543 assert(sd[sd_len] == '\0'); 544 assert(sd[sd_len-1] == ']'); 545 assert(sd[sd_len-2] == '"'); 546 547 if (!sign_msg_sign(&buffer, sd, sizeof(sd))) 548 return 0; 549 DPRINTF((D_CALL|D_SIGN), "sign_send_certificate_block(): " 550 "calling fprintlog()\n"); 551 552 STAILQ_FOREACH(fq, &sg->files, entries) { 553 /* we have to preserve the f_prevcount */ 554 int tmpcnt; 555 tmpcnt = fq->f->f_prevcount; 556 fprintlog(fq->f, buffer, NULL); 557 fq->f->f_prevcount = tmpcnt; 558 } 559 sign_inc_gbc(); 560 DELREF(buffer); 561 payload_index += fragment_len; 562 } 563 sg->resendcount--; 564 return true; 565 } 566 567 /* 568 * determine the SG for a message 569 * returns NULL if -sign not configured or no SG for this priority 570 */ 571 struct signature_group_t * 572 sign_get_sg(int pri, struct filed *f) 573 { 574 struct signature_group_t *sg, *rc = NULL; 575 576 if (GlobalSign.rsid && f) 577 switch (GlobalSign.sg) { 578 case 0: 579 rc = f->f_sg; 580 break; 581 case 1: 582 case 2: 583 STAILQ_FOREACH(sg, &GlobalSign.SigGroups, entries) { 584 if (sg->spri >= (unsigned int)pri) { 585 rc = sg; 586 break; 587 } 588 } 589 break; 590 case 3: 591 if (f->f_flags & FFLAG_SIGN) 592 rc = f->f_sg; 593 else 594 rc = NULL; 595 break; 596 } 597 598 DPRINTF((D_CALL|D_SIGN), "sign_get_sg(%d, %p) --> %p\n", pri, f, rc); 599 return rc; 600 } 601 602 /* 603 * create and send signature block 604 * 605 * uses a sliding window for redundancy 606 * if force==true then simply send all available hashes, e.g. on shutdown 607 * 608 * sliding window checks implicitly assume that new hashes are appended 609 * to the SG between two calls. if that is not the case (e.g. with repeated 610 * messages) the queue size will shrink. 611 * this has no negative consequences except generating more and shorter SBs 612 * than expected and confusing the operator because two consecutive SBs will 613 * have same FMNn 614 */ 615 unsigned 616 sign_send_signature_block(struct signature_group_t *sg, bool force) 617 { 618 char sd[SIGN_MAX_SD_LENGTH]; 619 size_t sd_len; 620 size_t sg_num_hashes = 0; /* hashes in SG queue */ 621 size_t hashes_in_sb = 0; /* number of hashes in current SB */ 622 size_t hashes_sent = 0; /* count of hashes sent */ 623 struct string_queue *qentry, *old_qentry; 624 struct buf_msg *buffer; 625 struct filed_queue *fq; 626 size_t i; 627 628 if (!sg) return 0; 629 DPRINTF((D_CALL|D_SIGN), "sign_send_signature_block(%p, %d)\n", 630 sg, force); 631 632 STAILQ_FOREACH(qentry, &sg->hashes, entries) 633 sg_num_hashes++; 634 635 /* only act if a division is full */ 636 if (!sg_num_hashes 637 || (!force && (sg_num_hashes % SIGN_HASH_DIVISION_NUM))) 638 return 0; 639 640 /* if no CB sent so far then do now, just before first SB */ 641 if (sg->resendcount == SIGN_RESENDCOUNT_CERTBLOCK) 642 sign_send_certificate_block(sg); 643 644 /* shortly after reboot we have shorter SBs */ 645 hashes_in_sb = MIN(sg_num_hashes, SIGN_HASH_NUM); 646 647 DPRINTF(D_SIGN, "sign_send_signature_block(): " 648 "sg_num_hashes = %zu, hashes_in_sb = %zu, SIGN_HASH_NUM = %d\n", 649 sg_num_hashes, hashes_in_sb, SIGN_HASH_NUM); 650 if (sg_num_hashes > SIGN_HASH_NUM) { 651 DPRINTF(D_SIGN, "sign_send_signature_block(): sg_num_hashes" 652 " > SIGN_HASH_NUM -- This should not happen!\n"); 653 } 654 655 /* now the SD */ 656 qentry = STAILQ_FIRST(&sg->hashes); 657 sd_len = snprintf(sd, sizeof(sd), "[ssign " 658 "VER=\"%s\" RSID=\"%" PRIuFAST64 "\" SG=\"%d\" " 659 "SPRI=\"%d\" GBC=\"%" PRIuFAST64 "\" FMN=\"%" PRIuFAST64 "\" " 660 "CNT=\"%zu\" HB=\"", 661 GlobalSign.ver, GlobalSign.rsid, GlobalSign.sg, 662 sg->spri, GlobalSign.gbc, qentry->key, 663 hashes_in_sb); 664 while (hashes_sent < hashes_in_sb) { 665 assert(qentry); 666 sd_len += snprintf(sd+sd_len, sizeof(sd)-sd_len, "%s ", 667 qentry->data); 668 hashes_sent++; 669 qentry = STAILQ_NEXT(qentry, entries); 670 } 671 /* overwrite last space and close SD */ 672 assert(sd_len < sizeof(sd)); 673 assert(sd[sd_len] == '\0'); 674 assert(sd[sd_len-1] == ' '); 675 sd[sd_len-1] = '\0'; 676 sd_len = strlcat(sd, "\" SIGN=\"\"]", sizeof(sd)); 677 678 if (sign_msg_sign(&buffer, sd, sizeof(sd))) { 679 DPRINTF((D_CALL|D_SIGN), "sign_send_signature_block(): calling" 680 " fprintlog(), sending %zu out of %zu hashes\n", 681 MIN(SIGN_MAX_HASH_NUM, sg_num_hashes), sg_num_hashes); 682 683 STAILQ_FOREACH(fq, &sg->files, entries) { 684 int tmpcnt; 685 tmpcnt = fq->f->f_prevcount; 686 fprintlog(fq->f, buffer, NULL); 687 fq->f->f_prevcount = tmpcnt; 688 } 689 sign_inc_gbc(); 690 DELREF(buffer); 691 } 692 /* always drop the oldest division of hashes */ 693 if (sg_num_hashes >= SIGN_HASH_NUM) { 694 qentry = STAILQ_FIRST(&sg->hashes); 695 for (i = 0; i < SIGN_HASH_DIVISION_NUM; i++) { 696 old_qentry = qentry; 697 qentry = STAILQ_NEXT(old_qentry, entries); 698 STAILQ_REMOVE(&sg->hashes, old_qentry, 699 string_queue, entries); 700 FREEPTR(old_qentry->data); 701 FREEPTR(old_qentry); 702 } 703 } 704 return hashes_sent; 705 } 706 707 void 708 sign_free_hashes(struct signature_group_t *sg) 709 { 710 DPRINTF((D_CALL|D_SIGN), "sign_free_hashes(%p)\n", sg); 711 sign_free_string_queue(&sg->hashes); 712 } 713 714 void 715 sign_free_string_queue(struct string_queue_head *sqhead) 716 { 717 struct string_queue *qentry, *tmp_qentry; 718 719 DPRINTF((D_CALL|D_SIGN), "sign_free_string_queue(%p)\n", sqhead); 720 STAILQ_FOREACH_SAFE(qentry, sqhead, entries, tmp_qentry) { 721 STAILQ_REMOVE(sqhead, qentry, string_queue, entries); 722 FREEPTR(qentry->data); 723 free(qentry); 724 } 725 assert(STAILQ_EMPTY(sqhead)); 726 } 727 728 /* 729 * hash one syslog message 730 */ 731 bool 732 sign_msg_hash(char *line, char **hash) 733 { 734 unsigned char md_value[EVP_MAX_MD_SIZE]; 735 unsigned char md_b64[EVP_MAX_MD_SIZE*2]; 736 /* TODO: exact expression for b64 length? */ 737 unsigned md_len = 0; 738 739 DPRINTF((D_CALL|D_SIGN), "sign_msg_hash('%s')\n", line); 740 741 SSL_CHECK_ONE(EVP_DigestInit_ex(GlobalSign.mdctx, GlobalSign.md, NULL)); 742 SSL_CHECK_ONE(EVP_DigestUpdate(GlobalSign.mdctx, line, strlen(line))); 743 SSL_CHECK_ONE(EVP_DigestFinal_ex(GlobalSign.mdctx, md_value, &md_len)); 744 745 b64_ntop(md_value, md_len, (char *)md_b64, EVP_MAX_MD_SIZE*2); 746 *hash = strdup((char *)md_b64); 747 748 DPRINTF((D_CALL|D_SIGN), "sign_msg_hash() --> \"%s\"\n", *hash); 749 return true; 750 } 751 752 /* 753 * append hash to SG queue 754 */ 755 bool 756 sign_append_hash(char *hash, struct signature_group_t *sg) 757 { 758 struct string_queue *qentry; 759 760 /* if one SG is shared by several destinations 761 * prevent duplicate entries */ 762 if ((qentry = STAILQ_LAST(&sg->hashes, string_queue, entries)) 763 && !strcmp(qentry->data, hash)) { 764 DPRINTF((D_CALL|D_SIGN), "sign_append_hash('%s', %p): " 765 "hash already in queue\n", hash, sg); 766 return false; 767 } 768 769 MALLOC(qentry, sizeof(*qentry)); 770 qentry->key = sign_assign_msg_num(sg); 771 qentry->data = hash; 772 STAILQ_INSERT_TAIL(&sg->hashes, qentry, entries); 773 DPRINTF((D_CALL|D_SIGN), "sign_append_hash('%s', %p): " 774 "#%" PRIdFAST64 "\n", hash, sg, qentry->key); 775 return true; 776 } 777 778 /* 779 * sign one syslog-sign message 780 * 781 * requires a ssign or ssigt-cert SD element 782 * ending with ' SIGN=""]' in sd 783 * linesize is available memory (= sizeof(sd)) 784 * 785 * function will calculate signature and return a new buffer 786 */ 787 bool 788 sign_msg_sign(struct buf_msg **bufferptr, char *sd, size_t linesize) 789 { 790 char *signature, *line; 791 size_t linelen, tlsprefixlen, endptr, newlinelen; 792 struct buf_msg *buffer; 793 794 DPRINTF((D_CALL|D_SIGN), "sign_msg_sign()\n"); 795 endptr = strlen(sd); 796 797 assert(endptr < linesize); 798 assert(sd[endptr] == '\0'); 799 assert(sd[endptr-1] == ']'); 800 assert(sd[endptr-2] == '"'); 801 802 /* set up buffer */ 803 buffer = buf_msg_new(0); 804 buffer->timestamp = strdup(make_timestamp(NULL, !BSDOutputFormat)); 805 buffer->prog = appname; 806 buffer->pid = include_pid; 807 buffer->recvhost = buffer->host = LocalFQDN; 808 buffer->pri = 110; 809 buffer->flags = IGN_CONS|SIGN_MSG; 810 buffer->sd = sd; 811 812 /* SD ready, now format and sign */ 813 if (!format_buffer(buffer, &line, &linelen, NULL, 814 &tlsprefixlen, NULL)) { 815 DPRINTF((D_CALL|D_SIGN), "sign_send_signature_block():" 816 " format_buffer() failed\n"); 817 buffer->sd = NULL; 818 DELREF(buffer); 819 return false; 820 } 821 if (!sign_string_sign(line+tlsprefixlen, &signature)) { 822 DPRINTF((D_CALL|D_SIGN), "sign_send_signature_block():" 823 " sign_string_sign() failed\n"); 824 buffer->sd = NULL; 825 DELREF(buffer); 826 FREEPTR(line); 827 return false; 828 } 829 FREEPTR(line); 830 sd[endptr-2] = '\0'; 831 newlinelen = strlcat(sd, signature, linesize); 832 newlinelen = strlcat(sd, "\"]", linesize); 833 834 if (newlinelen >= linesize) { 835 DPRINTF(D_SIGN, "sign_send_signature_block(): " 836 "buffer too small\n"); 837 buffer->sd = NULL; 838 DELREF(buffer); 839 return false; 840 } 841 assert(newlinelen < linesize); 842 assert(sd[newlinelen] == '\0'); 843 assert(sd[newlinelen-1] == ']'); 844 assert(sd[newlinelen-2] == '"'); 845 846 buffer->sd = strdup(sd); 847 *bufferptr = buffer; 848 return true; 849 } 850 851 /* 852 * sign one string 853 */ 854 bool 855 sign_string_sign(char *line, char **signature) 856 { 857 char buf[SIGN_MAX_LENGTH+1]; 858 unsigned char sig_value[SIGN_B64SIGLEN_DSS]; 859 unsigned char sig_b64[SIGN_B64SIGLEN_DSS]; 860 unsigned sig_len = 0; 861 char *p, *q; 862 /* 863 * The signature is calculated over the completely formatted 864 * syslog-message, including all of the PRI, HEADER, and hashes 865 * in the hash block, excluding spaces between fields, and also 866 * excluding the signature field (SD Parameter Name "SIGN", "=", 867 * and corresponding value). 868 * 869 * -- I am not quite sure which spaces are to be removed. 870 * Only the ones inside the "ssign" element or those between 871 * header fields as well? 872 */ 873 /* removes the string ' SIGN=""' */ 874 for (p = line, q = buf; 875 *p && (q - buf <= SIGN_MAX_LENGTH);) { 876 if (strncmp(p, " SIGN=\"\"", 8) == 0) 877 p += 8; 878 *q++ = *p++; 879 } 880 *q = '\0'; 881 882 SSL_CHECK_ONE(EVP_SignInit(GlobalSign.sigctx, GlobalSign.sig)); 883 SSL_CHECK_ONE(EVP_SignUpdate(GlobalSign.sigctx, buf, q-buf)); 884 assert(GlobalSign.privkey); 885 SSL_CHECK_ONE(EVP_SignFinal(GlobalSign.sigctx, sig_value, &sig_len, 886 GlobalSign.privkey)); 887 888 b64_ntop(sig_value, sig_len, (char *)sig_b64, sizeof(sig_b64)); 889 *signature = strdup((char *)sig_b64); 890 891 DPRINTF((D_CALL|D_SIGN), "sign_string_sign('%s') --> '%s'\n", 892 buf, *signature); 893 return *signature != NULL; 894 } 895 896 void 897 sign_new_reboot_session(void) 898 { 899 struct signature_group_t *sg; 900 901 DPRINTF((D_CALL|D_SIGN), "sign_new_reboot_session()\n"); 902 903 /* global counters */ 904 GlobalSign.gbc = 0; 905 /* might be useful for later analysis: 906 * rebooted session IDs are sequential, 907 * normal IDs are almost always not */ 908 GlobalSign.rsid++; 909 910 assert(GlobalSign.sg <= 3); 911 /* reset SGs */ 912 STAILQ_FOREACH(sg, &GlobalSign.SigGroups, entries) { 913 sg->resendcount = SIGN_RESENDCOUNT_CERTBLOCK; 914 sg->last_msg_num = 1; 915 } 916 } 917 918 /* get msg_num, increment counter, check overflow */ 919 uint_fast64_t 920 sign_assign_msg_num(struct signature_group_t *sg) 921 { 922 uint_fast64_t old; 923 924 old = sg->last_msg_num++; 925 if (sg->last_msg_num > SIGN_MAX_COUNT) 926 sign_new_reboot_session(); 927 return old; 928 } 929 930 931 /* increment gbc, check overflow */ 932 void 933 sign_inc_gbc(void) 934 { 935 if (++GlobalSign.gbc > SIGN_MAX_COUNT) 936 sign_new_reboot_session(); 937 } 938 #endif /* !DISABLE_SIGN */ 939