1 /* $NetBSD: sign.c,v 1.3 2009/01/18 10:35:26 lukem 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 1.3 2009/01/18 10:35:26 lukem 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() 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 return false; 262 } 263 b64_ntop(der_pubkey, der_len, pubkey_b64, der_len*2); 264 free(der_pubkey); 265 /* try to resize memory object as needed */ 266 GlobalSign.pubkey_b64 = realloc(pubkey_b64, 267 strlen(pubkey_b64) + 1); 268 if (!GlobalSign.pubkey_b64) 269 GlobalSign.pubkey_b64 = pubkey_b64; 270 } 271 return true; 272 } 273 274 /* 275 * init SGs 276 */ 277 bool 278 sign_sg_init(struct filed *Files) 279 { 280 struct signature_group_t *sg, *newsg, *last_sg; 281 struct filed_queue *fq; 282 struct string_queue *sqentry, *last_sqentry; 283 struct filed *f; 284 unsigned int i; 285 286 /* note on SG 1 and 2: 287 * it is assumed that redundant signature groups 288 * and especially signature groups without an associated 289 * destination are harmless. 290 * this currently holds true because sign_append_hash() 291 * is called from fprintlog(), so only actually used 292 * signature group get hashes and need memory for them 293 */ 294 /* possible optimization for SGs 1 and 2: 295 * use a struct signature_group_t *newsg[IETF_NUM_PRIVALUES] 296 * for direct group lookup 297 */ 298 299 #define ALLOC_OR_FALSE(x) do { \ 300 if(!((x) = calloc(1, sizeof(*(x))))) { \ 301 logerror("Unable to allocate memory"); \ 302 return false; \ 303 } \ 304 } while (/*CONSTCOND*/0) 305 306 #define ALLOC_SG(x) do { \ 307 ALLOC_OR_FALSE(x); \ 308 (x)->last_msg_num = 1; /* cf. section 4.2.5 */ \ 309 STAILQ_INIT(&(x)->hashes); \ 310 STAILQ_INIT(&(x)->files); \ 311 } while (/*CONSTCOND*/0) 312 313 /* alloc(fq) and add to SGs file queue */ 314 #define ASSIGN_FQ() do { \ 315 ALLOC_OR_FALSE(fq); \ 316 fq->f = f; \ 317 f->f_sg = newsg; \ 318 DPRINTF(D_SIGN, "SG@%p <--> f@%p\n", newsg, f); \ 319 STAILQ_INSERT_TAIL(&newsg->files, fq, entries); \ 320 } while (/*CONSTCOND*/0) 321 322 switch (GlobalSign.sg) { 323 case 0: 324 /* one SG, linked to all files */ 325 ALLOC_SG(newsg); 326 newsg->spri = 0; 327 for (f = Files; f; f = f->f_next) 328 ASSIGN_FQ(); 329 STAILQ_INSERT_TAIL(&GlobalSign.SigGroups, 330 newsg, entries); 331 break; 332 case 1: 333 /* every PRI gets one SG */ 334 for (i = 0; i < IETF_NUM_PRIVALUES; i++) { 335 int fac, prilev; 336 fac = LOG_FAC(i); 337 prilev = LOG_PRI(i); 338 ALLOC_SG(newsg); 339 newsg->spri = i; 340 341 /* now find all destinations associated with this SG */ 342 for (f = Files; f; f = f->f_next) 343 /* check priorities */ 344 if (MATCH_PRI(f, fac, prilev)) 345 ASSIGN_FQ(); 346 STAILQ_INSERT_TAIL(&GlobalSign.SigGroups, 347 newsg, entries); 348 } 349 break; 350 case 2: 351 /* PRI ranges get one SG, boundaries given by the 352 * SPRI, indicating the largest PRI in the SG 353 * 354 * either GlobalSign.sig2_delims has a list of 355 * user configured delimiters, or we use a default 356 * and set up one SG per facility 357 */ 358 if (STAILQ_EMPTY(&GlobalSign.sig2_delims)) { 359 DPRINTF(D_SIGN, "sign_sg_init(): set default " 360 "values for SG 2\n"); 361 for (i = 0; i < (IETF_NUM_PRIVALUES>>3); i++) { 362 ALLOC_OR_FALSE(sqentry); 363 sqentry->data = NULL; 364 sqentry->key = (i<<3); 365 STAILQ_INSERT_TAIL(&GlobalSign.sig2_delims, 366 sqentry, entries); 367 } 368 } 369 assert(!STAILQ_EMPTY(&GlobalSign.sig2_delims)); 370 371 /* add one more group at the end */ 372 last_sqentry = STAILQ_LAST(&GlobalSign.sig2_delims, 373 string_queue, entries); 374 if (last_sqentry->key < IETF_NUM_PRIVALUES) { 375 ALLOC_OR_FALSE(sqentry); 376 sqentry->data = NULL; 377 sqentry->key = IETF_NUM_PRIVALUES-1; 378 STAILQ_INSERT_TAIL(&GlobalSign.sig2_delims, 379 sqentry, entries); 380 } 381 382 STAILQ_FOREACH(sqentry, &GlobalSign.sig2_delims, entries) { 383 unsigned int min_pri = 0; 384 ALLOC_SG(newsg); 385 newsg->spri = sqentry->key; 386 387 /* check _all_ priorities in SG */ 388 last_sg = STAILQ_LAST(&GlobalSign.SigGroups, 389 signature_group_t, entries); 390 if (last_sg) 391 min_pri = last_sg->spri + 1; 392 393 DPRINTF(D_SIGN, "sign_sg_init(): add SG@%p: SG=\"2\"," 394 " SPRI=\"%d\" -- for msgs with " 395 "%d <= pri <= %d\n", 396 newsg, newsg->spri, min_pri, newsg->spri); 397 /* now find all destinations associated with this SG */ 398 for (f = Files; f; f = f->f_next) { 399 bool match = false; 400 for (i = min_pri; i <= newsg->spri; i++) { 401 int fac, prilev; 402 fac = LOG_FAC(i); 403 prilev = LOG_PRI(i); 404 if (MATCH_PRI(f, fac, prilev)) { 405 match = true; 406 break; 407 } 408 } 409 if (match) 410 ASSIGN_FQ(); 411 } 412 STAILQ_INSERT_TAIL(&GlobalSign.SigGroups, 413 newsg, entries); 414 } 415 break; 416 case 3: 417 /* every file (with flag) gets one SG */ 418 for (f = Files; f; f = f->f_next) { 419 if (!(f->f_flags & FFLAG_SIGN)) { 420 f->f_sg = NULL; 421 continue; 422 } 423 ALLOC_SG(newsg); 424 newsg->spri = f->f_file; /* not needed but shows SGs */ 425 ASSIGN_FQ(); 426 STAILQ_INSERT_TAIL(&GlobalSign.SigGroups, 427 newsg, entries); 428 } 429 break; 430 } 431 DPRINTF((D_PARSE|D_SIGN), "sign_sg_init() set up these " 432 "Signature Groups:\n"); 433 STAILQ_FOREACH(sg, &GlobalSign.SigGroups, entries) { 434 DPRINTF((D_PARSE|D_SIGN), "SG@%p with SG=\"%d\", SPRI=\"%d\"," 435 " associated files:\n", sg, GlobalSign.sg, sg->spri); 436 STAILQ_FOREACH(fq, &sg->files, entries) { 437 DPRINTF((D_PARSE|D_SIGN), " f@%p with type %d\n", 438 fq->f, fq->f->f_type); 439 } 440 } 441 return true; 442 } 443 444 /* 445 * free all SGs for a given algorithm 446 */ 447 void 448 sign_global_free() 449 { 450 struct signature_group_t *sg, *tmp_sg; 451 struct filed_queue *fq, *tmp_fq; 452 453 DPRINTF((D_CALL|D_SIGN), "sign_global_free()\n"); 454 STAILQ_FOREACH_SAFE(sg, &GlobalSign.SigGroups, entries, tmp_sg) { 455 if (!STAILQ_EMPTY(&sg->hashes)) { 456 /* send CB and SB twice to get minimal redundancy 457 * for the last few message hashes */ 458 sign_send_certificate_block(sg); 459 sign_send_certificate_block(sg); 460 sign_send_signature_block(sg, true); 461 sign_send_signature_block(sg, true); 462 sign_free_hashes(sg); 463 } 464 fq = STAILQ_FIRST(&sg->files); 465 while (fq != NULL) { 466 tmp_fq = STAILQ_NEXT(fq, entries); 467 free(fq); 468 fq = tmp_fq; 469 } 470 STAILQ_REMOVE(&GlobalSign.SigGroups, 471 sg, signature_group_t, entries); 472 free(sg); 473 } 474 sign_free_string_queue(&GlobalSign.sig2_delims); 475 476 if (GlobalSign.privkey) { 477 GlobalSign.privkey = NULL; 478 } 479 if (GlobalSign.pubkey) { 480 EVP_PKEY_free(GlobalSign.pubkey); 481 GlobalSign.pubkey = NULL; 482 } 483 if(GlobalSign.mdctx) { 484 EVP_MD_CTX_destroy(GlobalSign.mdctx); 485 GlobalSign.mdctx = NULL; 486 } 487 if(GlobalSign.sigctx) { 488 EVP_MD_CTX_destroy(GlobalSign.sigctx); 489 GlobalSign.sigctx = NULL; 490 } 491 FREEPTR(GlobalSign.pubkey_b64); 492 } 493 494 /* 495 * create and send certificate block 496 */ 497 bool 498 sign_send_certificate_block(struct signature_group_t *sg) 499 { 500 struct filed_queue *fq; 501 struct buf_msg *buffer; 502 char *tstamp; 503 char payload[SIGN_MAX_PAYLOAD_LENGTH]; 504 char sd[SIGN_MAX_SD_LENGTH]; 505 size_t payload_len, sd_len, fragment_len; 506 size_t payload_index = 0; 507 508 /* do nothing if CBs already sent or if there was no message in SG */ 509 if (!sg->resendcount 510 || ((sg->resendcount == SIGN_RESENDCOUNT_CERTBLOCK) 511 && STAILQ_EMPTY(&sg->hashes))) 512 return false; 513 514 DPRINTF((D_CALL|D_SIGN), "sign_send_certificate_block(%p)\n", sg); 515 tstamp = make_timestamp(NULL, true); 516 517 payload_len = snprintf(payload, sizeof(payload), "%s %c %s", tstamp, 518 GlobalSign.keytype, GlobalSign.pubkey_b64); 519 if (payload_len >= sizeof(payload)) { 520 DPRINTF(D_SIGN, "Buffer too small for syslog-sign setup\n"); 521 return false; 522 } 523 524 while (payload_index < payload_len) { 525 if (payload_len - payload_index <= SIGN_MAX_FRAG_LENGTH) 526 fragment_len = payload_len - payload_index; 527 else 528 fragment_len = SIGN_MAX_FRAG_LENGTH; 529 530 /* format SD */ 531 sd_len = snprintf(sd, sizeof(sd), "[ssign-cert " 532 "VER=\"%s\" RSID=\"%" PRIuFAST64 "\" SG=\"%d\" " 533 "SPRI=\"%d\" TBPL=\"%zu\" INDEX=\"%zu\" " 534 "FLEN=\"%zu\" FRAG=\"%.*s\" " 535 "SIGN=\"\"]", 536 GlobalSign.ver, GlobalSign.rsid, GlobalSign.sg, 537 sg->spri, payload_len, payload_index+1, 538 fragment_len, (int)fragment_len, 539 &payload[payload_index]); 540 assert(sd_len < sizeof(sd)); 541 assert(sd[sd_len] == '\0'); 542 assert(sd[sd_len-1] == ']'); 543 assert(sd[sd_len-2] == '"'); 544 545 if (!sign_msg_sign(&buffer, sd, sizeof(sd))) 546 return 0; 547 DPRINTF((D_CALL|D_SIGN), "sign_send_certificate_block(): " 548 "calling fprintlog()\n"); 549 550 STAILQ_FOREACH(fq, &sg->files, entries) { 551 /* we have to preserve the f_prevcount */ 552 int tmpcnt; 553 tmpcnt = fq->f->f_prevcount; 554 fprintlog(fq->f, buffer, NULL); 555 fq->f->f_prevcount = tmpcnt; 556 } 557 sign_inc_gbc(); 558 DELREF(buffer); 559 payload_index += fragment_len; 560 } 561 sg->resendcount--; 562 return true; 563 } 564 565 /* 566 * determine the SG for a message 567 * returns NULL if -sign not configured or no SG for this priority 568 */ 569 struct signature_group_t * 570 sign_get_sg(int pri, struct filed *f) 571 { 572 struct signature_group_t *sg, *rc = NULL; 573 574 if (GlobalSign.rsid && f) 575 switch (GlobalSign.sg) { 576 case 0: 577 rc = f->f_sg; 578 break; 579 case 1: 580 case 2: 581 STAILQ_FOREACH(sg, &GlobalSign.SigGroups, entries) { 582 if (sg->spri >= (unsigned int)pri) { 583 rc = sg; 584 break; 585 } 586 } 587 break; 588 case 3: 589 if (f->f_flags & FFLAG_SIGN) 590 rc = f->f_sg; 591 else 592 rc = NULL; 593 break; 594 } 595 596 DPRINTF((D_CALL|D_SIGN), "sign_get_sg(%d, %p) --> %p\n", pri, f, rc); 597 return rc; 598 } 599 600 /* 601 * create and send signature block 602 * 603 * uses a sliding window for redundancy 604 * if force==true then simply send all available hashes, e.g. on shutdown 605 * 606 * sliding window checks implicitly assume that new hashes are appended 607 * to the SG between two calls. if that is not the case (e.g. with repeated 608 * messages) the queue size will shrink. 609 * this has no negative consequences except generating more and shorter SBs 610 * than expected and confusing the operator because two consecutive SBs will 611 * have same FMNn 612 */ 613 unsigned 614 sign_send_signature_block(struct signature_group_t *sg, bool force) 615 { 616 char sd[SIGN_MAX_SD_LENGTH]; 617 size_t sd_len; 618 size_t sg_num_hashes = 0; /* hashes in SG queue */ 619 size_t hashes_in_sb = 0; /* number of hashes in current SB */ 620 size_t hashes_sent = 0; /* count of hashes sent */ 621 struct string_queue *qentry, *old_qentry; 622 struct buf_msg *buffer; 623 struct filed_queue *fq; 624 size_t i; 625 626 if (!sg) return 0; 627 DPRINTF((D_CALL|D_SIGN), "sign_send_signature_block(%p, %d)\n", 628 sg, force); 629 630 STAILQ_FOREACH(qentry, &sg->hashes, entries) 631 sg_num_hashes++; 632 633 /* only act if a division is full */ 634 if (!sg_num_hashes 635 || (!force && (sg_num_hashes % SIGN_HASH_DIVISION_NUM))) 636 return 0; 637 638 /* if no CB sent so far then do now, just before first SB */ 639 if (sg->resendcount == SIGN_RESENDCOUNT_CERTBLOCK) 640 sign_send_certificate_block(sg); 641 642 /* shortly after reboot we have shorter SBs */ 643 hashes_in_sb = MIN(sg_num_hashes, SIGN_HASH_NUM); 644 645 DPRINTF(D_SIGN, "sign_send_signature_block(): " 646 "sg_num_hashes = %zu, hashes_in_sb = %zu, SIGN_HASH_NUM = %d\n", 647 sg_num_hashes, hashes_in_sb, SIGN_HASH_NUM); 648 if (sg_num_hashes > SIGN_HASH_NUM) { 649 DPRINTF(D_SIGN, "sign_send_signature_block(): sg_num_hashes" 650 " > SIGN_HASH_NUM -- This should not happen!\n"); 651 } 652 653 /* now the SD */ 654 qentry = STAILQ_FIRST(&sg->hashes); 655 sd_len = snprintf(sd, sizeof(sd), "[ssign " 656 "VER=\"%s\" RSID=\"%" PRIuFAST64 "\" SG=\"%d\" " 657 "SPRI=\"%d\" GBC=\"%" PRIuFAST64 "\" FMN=\"%" PRIuFAST64 "\" " 658 "CNT=\"%zu\" HB=\"", 659 GlobalSign.ver, GlobalSign.rsid, GlobalSign.sg, 660 sg->spri, GlobalSign.gbc, qentry->key, 661 hashes_in_sb); 662 while (hashes_sent < hashes_in_sb) { 663 assert(qentry); 664 sd_len += snprintf(sd+sd_len, sizeof(sd)-sd_len, "%s ", 665 qentry->data); 666 hashes_sent++; 667 qentry = STAILQ_NEXT(qentry, entries); 668 } 669 /* overwrite last space and close SD */ 670 assert(sd_len < sizeof(sd)); 671 assert(sd[sd_len] == '\0'); 672 assert(sd[sd_len-1] == ' '); 673 sd[sd_len-1] = '\0'; 674 sd_len = strlcat(sd, "\" SIGN=\"\"]", sizeof(sd)); 675 676 if (sign_msg_sign(&buffer, sd, sizeof(sd))) { 677 DPRINTF((D_CALL|D_SIGN), "sign_send_signature_block(): calling" 678 " fprintlog(), sending %zu out of %zu hashes\n", 679 MIN(SIGN_MAX_HASH_NUM, sg_num_hashes), sg_num_hashes); 680 681 STAILQ_FOREACH(fq, &sg->files, entries) { 682 int tmpcnt; 683 tmpcnt = fq->f->f_prevcount; 684 fprintlog(fq->f, buffer, NULL); 685 fq->f->f_prevcount = tmpcnt; 686 } 687 sign_inc_gbc(); 688 DELREF(buffer); 689 } 690 /* always drop the oldest division of hashes */ 691 if (sg_num_hashes >= SIGN_HASH_NUM) { 692 qentry = STAILQ_FIRST(&sg->hashes); 693 for (i = 0; i < SIGN_HASH_DIVISION_NUM; i++) { 694 old_qentry = qentry; 695 qentry = STAILQ_NEXT(old_qentry, entries); 696 STAILQ_REMOVE(&sg->hashes, old_qentry, 697 string_queue, entries); 698 FREEPTR(old_qentry->data); 699 FREEPTR(old_qentry); 700 } 701 } 702 return hashes_sent; 703 } 704 705 void 706 sign_free_hashes(struct signature_group_t *sg) 707 { 708 DPRINTF((D_CALL|D_SIGN), "sign_free_hashes(%p)\n", sg); 709 sign_free_string_queue(&sg->hashes); 710 } 711 712 void 713 sign_free_string_queue(struct string_queue_head *sqhead) 714 { 715 struct string_queue *qentry, *tmp_qentry; 716 717 DPRINTF((D_CALL|D_SIGN), "sign_free_string_queue(%p)\n", sqhead); 718 STAILQ_FOREACH_SAFE(qentry, sqhead, entries, tmp_qentry) { 719 STAILQ_REMOVE(sqhead, qentry, string_queue, entries); 720 FREEPTR(qentry->data); 721 free(qentry); 722 } 723 assert(STAILQ_EMPTY(sqhead)); 724 } 725 726 /* 727 * hash one syslog message 728 */ 729 bool 730 sign_msg_hash(char *line, char **hash) 731 { 732 unsigned char md_value[EVP_MAX_MD_SIZE]; 733 unsigned char md_b64[EVP_MAX_MD_SIZE*2]; 734 /* TODO: exact expression for b64 length? */ 735 unsigned md_len = 0; 736 737 DPRINTF((D_CALL|D_SIGN), "sign_msg_hash('%s')\n", line); 738 739 SSL_CHECK_ONE(EVP_DigestInit_ex(GlobalSign.mdctx, GlobalSign.md, NULL)); 740 SSL_CHECK_ONE(EVP_DigestUpdate(GlobalSign.mdctx, line, strlen(line))); 741 SSL_CHECK_ONE(EVP_DigestFinal_ex(GlobalSign.mdctx, md_value, &md_len)); 742 743 b64_ntop(md_value, md_len, (char *)md_b64, EVP_MAX_MD_SIZE*2); 744 *hash = strdup((char *)md_b64); 745 746 DPRINTF((D_CALL|D_SIGN), "sign_msg_hash() --> \"%s\"\n", *hash); 747 return true; 748 } 749 750 /* 751 * append hash to SG queue 752 */ 753 bool 754 sign_append_hash(char *hash, struct signature_group_t *sg) 755 { 756 struct string_queue *qentry; 757 758 /* if one SG is shared by several destinations 759 * prevent duplicate entries */ 760 if ((qentry = STAILQ_LAST(&sg->hashes, string_queue, entries)) 761 && !strcmp(qentry->data, hash)) { 762 DPRINTF((D_CALL|D_SIGN), "sign_append_hash('%s', %p): " 763 "hash already in queue\n", hash, sg); 764 return false; 765 } 766 767 MALLOC(qentry, sizeof(*qentry)); 768 qentry->key = sign_assign_msg_num(sg); 769 qentry->data = hash; 770 STAILQ_INSERT_TAIL(&sg->hashes, qentry, entries); 771 DPRINTF((D_CALL|D_SIGN), "sign_append_hash('%s', %p): " 772 "#%" PRIdFAST64 "\n", hash, sg, qentry->key); 773 return true; 774 } 775 776 /* 777 * sign one syslog-sign message 778 * 779 * requires a ssign or ssigt-cert SD element 780 * ending with ' SIGN=""]' in sd 781 * linesize is available memory (= sizeof(sd)) 782 * 783 * function will calculate signature and return a new buffer 784 */ 785 bool 786 sign_msg_sign(struct buf_msg **bufferptr, char *sd, size_t linesize) 787 { 788 char *signature, *line; 789 size_t linelen, tlsprefixlen, endptr, newlinelen; 790 struct buf_msg *buffer; 791 792 DPRINTF((D_CALL|D_SIGN), "sign_msg_sign()\n"); 793 endptr = strlen(sd); 794 795 assert(endptr < linesize); 796 assert(sd[endptr] == '\0'); 797 assert(sd[endptr-1] == ']'); 798 assert(sd[endptr-2] == '"'); 799 800 /* set up buffer */ 801 buffer = buf_msg_new(0); 802 buffer->timestamp = strdup(make_timestamp(NULL, !BSDOutputFormat)); 803 buffer->prog = appname; 804 buffer->pid = include_pid; 805 buffer->recvhost = buffer->host = LocalFQDN; 806 buffer->pri = 110; 807 buffer->flags = IGN_CONS|SIGN_MSG; 808 buffer->sd = sd; 809 810 /* SD ready, now format and sign */ 811 if (!format_buffer(buffer, &line, &linelen, NULL, 812 &tlsprefixlen, NULL)) { 813 DPRINTF((D_CALL|D_SIGN), "sign_send_signature_block():" 814 " format_buffer() failed\n"); 815 buffer->sd = NULL; 816 DELREF(buffer); 817 return false; 818 } 819 if (!sign_string_sign(line+tlsprefixlen, &signature)) { 820 DPRINTF((D_CALL|D_SIGN), "sign_send_signature_block():" 821 " sign_string_sign() failed\n"); 822 buffer->sd = NULL; 823 DELREF(buffer); 824 FREEPTR(line); 825 return false; 826 } 827 FREEPTR(line); 828 sd[endptr-2] = '\0'; 829 newlinelen = strlcat(sd, signature, linesize); 830 newlinelen = strlcat(sd, "\"]", linesize); 831 832 if (newlinelen >= linesize) { 833 DPRINTF(D_SIGN, "sign_send_signature_block(): " 834 "buffer too small\n"); 835 buffer->sd = NULL; 836 DELREF(buffer); 837 return false; 838 } 839 assert(newlinelen < linesize); 840 assert(sd[newlinelen] == '\0'); 841 assert(sd[newlinelen-1] == ']'); 842 assert(sd[newlinelen-2] == '"'); 843 844 buffer->sd = strdup(sd); 845 *bufferptr = buffer; 846 return true; 847 } 848 849 /* 850 * sign one string 851 */ 852 bool 853 sign_string_sign(char *line, char **signature) 854 { 855 char buf[SIGN_MAX_LENGTH+1]; 856 unsigned char sig_value[SIGN_B64SIGLEN_DSS]; 857 unsigned char sig_b64[SIGN_B64SIGLEN_DSS]; 858 unsigned sig_len = 0; 859 char *p, *q; 860 /* 861 * The signature is calculated over the completely formatted 862 * syslog-message, including all of the PRI, HEADER, and hashes 863 * in the hash block, excluding spaces between fields, and also 864 * excluding the signature field (SD Parameter Name "SIGN", "=", 865 * and corresponding value). 866 * 867 * -- I am not quite sure which spaces are to be removed. 868 * Only the ones inside the "ssign" element or those between 869 * header fields as well? 870 */ 871 /* removes the string ' SIGN=""' */ 872 for (p = line, q = buf; 873 *p && (q - buf <= SIGN_MAX_LENGTH);) { 874 if (strncmp(p, " SIGN=\"\"", 8) == 0) 875 p += 8; 876 *q++ = *p++; 877 } 878 *q = '\0'; 879 880 SSL_CHECK_ONE(EVP_SignInit(GlobalSign.sigctx, GlobalSign.sig)); 881 SSL_CHECK_ONE(EVP_SignUpdate(GlobalSign.sigctx, buf, q-buf)); 882 assert(GlobalSign.privkey); 883 SSL_CHECK_ONE(EVP_SignFinal(GlobalSign.sigctx, sig_value, &sig_len, 884 GlobalSign.privkey)); 885 886 b64_ntop(sig_value, sig_len, (char *)sig_b64, sizeof(sig_b64)); 887 *signature = strdup((char *)sig_b64); 888 889 DPRINTF((D_CALL|D_SIGN), "sign_string_sign('%s') --> '%s'\n", 890 buf, *signature); 891 return *signature != NULL; 892 } 893 894 void 895 sign_new_reboot_session() 896 { 897 struct signature_group_t *sg; 898 899 DPRINTF((D_CALL|D_SIGN), "sign_new_reboot_session()\n"); 900 901 /* global counters */ 902 GlobalSign.gbc = 0; 903 /* might be useful for later analysis: 904 * rebooted session IDs are sequential, 905 * normal IDs are almost always not */ 906 GlobalSign.rsid++; 907 908 assert(GlobalSign.sg <= 3); 909 /* reset SGs */ 910 STAILQ_FOREACH(sg, &GlobalSign.SigGroups, entries) { 911 sg->resendcount = SIGN_RESENDCOUNT_CERTBLOCK; 912 sg->last_msg_num = 1; 913 } 914 } 915 916 /* get msg_num, increment counter, check overflow */ 917 uint_fast64_t 918 sign_assign_msg_num(struct signature_group_t *sg) 919 { 920 uint_fast64_t old; 921 922 old = sg->last_msg_num++; 923 if (sg->last_msg_num > SIGN_MAX_COUNT) 924 sign_new_reboot_session(); 925 return old; 926 } 927 928 929 /* increment gbc, check overflow */ 930 void 931 sign_inc_gbc() 932 { 933 if (++GlobalSign.gbc > SIGN_MAX_COUNT) 934 sign_new_reboot_session(); 935 } 936 #endif /* !DISABLE_SIGN */ 937