ssl/record/methods/dtls_meth.c

   1 /*
   2  * Copyright 2018-2022 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the Apache License 2.0 (the "License").  You may not use
   5  * this file except in compliance with the License.  You can obtain a copy
   6  * in the file LICENSE in the source distribution or at
   7  * https://www.openssl.org/source/license.html
   8  */
   9
  10 #include <assert.h>
  11 #include "../../ssl_local.h"
  12 #include "../record_local.h"
  13 #include "recmethod_local.h"
  14
  15 /* mod 128 saturating subtract of two 64-bit values in big-endian order */
  16 static int satsub64be(const unsigned char *v1, const unsigned char *v2)
  17 {
  18     int64_t ret;
  19     uint64_t l1, l2;
  20
  21     n2l8(v1, l1);
  22     n2l8(v2, l2);
  23
  24     ret = l1 - l2;
  25
  26     /* We do not permit wrap-around */
  27     if (l1 > l2 && ret < 0)
  28         return 128;
  29     else if (l2 > l1 && ret > 0)
  30         return -128;
  31
  32     if (ret > 128)
  33         return 128;
  34     else if (ret < -128)
  35         return -128;
  36     else
  37         return (int)ret;
  38 }
  39
  40 static int dtls_record_replay_check(OSSL_RECORD_LAYER *rl, DTLS_BITMAP *bitmap)
  41 {
  42     int cmp;
  43     unsigned int shift;
  44     const unsigned char *seq = rl->sequence;
  45
  46     cmp = satsub64be(seq, bitmap->max_seq_num);
  47     if (cmp > 0) {
  48         SSL3_RECORD_set_seq_num(&rl->rrec[0], seq);
  49         return 1;               /* this record in new */
  50     }
  51     shift = -cmp;
  52     if (shift >= sizeof(bitmap->map) * 8)
  53         return 0;               /* stale, outside the window */
  54     else if (bitmap->map & ((uint64_t)1 << shift))
  55         return 0;               /* record previously received */
  56
  57     SSL3_RECORD_set_seq_num(&rl->rrec[0], seq);
  58     return 1;
  59 }
  60
  61 static void dtls_record_bitmap_update(OSSL_RECORD_LAYER *rl,
  62                                       DTLS_BITMAP *bitmap)
  63 {
  64     int cmp;
  65     unsigned int shift;
  66     const unsigned char *seq = rl->sequence;
  67
  68     cmp = satsub64be(seq, bitmap->max_seq_num);
  69     if (cmp > 0) {
  70         shift = cmp;
  71         if (shift < sizeof(bitmap->map) * 8)
  72             bitmap->map <<= shift, bitmap->map |= 1UL;
  73         else
  74             bitmap->map = 1UL;
  75         memcpy(bitmap->max_seq_num, seq, SEQ_NUM_SIZE);
  76     } else {
  77         shift = -cmp;
  78         if (shift < sizeof(bitmap->map) * 8)
  79             bitmap->map |= (uint64_t)1 << shift;
  80     }
  81 }
  82
  83 static DTLS_BITMAP *dtls_get_bitmap(OSSL_RECORD_LAYER *rl, SSL3_RECORD *rr,
  84                                     unsigned int *is_next_epoch)
  85 {
  86     *is_next_epoch = 0;
  87
  88     /* In current epoch, accept HM, CCS, DATA, & ALERT */
  89     if (rr->epoch == rl->epoch)
  90         return &rl->bitmap;
  91
  92     /*
  93      * Only HM and ALERT messages can be from the next epoch and only if we
  94      * have already processed all of the unprocessed records from the last
  95      * epoch
  96      */
  97     else if (rr->epoch == (unsigned long)(rl->epoch + 1)
  98              && rl->unprocessed_rcds.epoch != rl->epoch
  99              && (rr->type == SSL3_RT_HANDSHAKE || rr->type == SSL3_RT_ALERT)) {
 100         *is_next_epoch = 1;
 101         return &rl->next_bitmap;
 102     }
 103
 104     return NULL;
 105 }
 106
 107 static void dtls_set_in_init(OSSL_RECORD_LAYER *rl, int in_init)
 108 {
 109     rl->in_init = in_init;
 110 }
 111
 112 static int dtls_process_record(OSSL_RECORD_LAYER *rl, DTLS_BITMAP *bitmap)
 113 {
 114     int i;
 115     int enc_err;
 116     SSL3_RECORD *rr;
 117     int imac_size;
 118     size_t mac_size = 0;
 119     unsigned char md[EVP_MAX_MD_SIZE];
 120     SSL_MAC_BUF macbuf = { NULL, 0 };
 121     int ret = 0;
 122
 123     rr = &rl->rrec[0];
 124
 125     /*
 126      * At this point, rl->packet_length == DTLS1_RT_HEADER_LENGTH + rr->length,
 127      * and we have that many bytes in rl->packet
 128      */
 129     rr->input = &(rl->packet[DTLS1_RT_HEADER_LENGTH]);
 130
 131     /*
 132      * ok, we can now read from 'rl->packet' data into 'rr'. rr->input
 133      * points at rr->length bytes, which need to be copied into rr->data by
 134      * either the decryption or by the decompression. When the data is 'copied'
 135      * into the rr->data buffer, rr->input will be pointed at the new buffer
 136      */
 137
 138     /*
 139      * We now have - encrypted [ MAC [ compressed [ plain ] ] ] rr->length
 140      * bytes of encrypted compressed stuff.
 141      */
 142
 143     /* check is not needed I believe */
 144     if (rr->length > SSL3_RT_MAX_ENCRYPTED_LENGTH) {
 145         RLAYERfatal(rl, SSL_AD_RECORD_OVERFLOW, SSL_R_ENCRYPTED_LENGTH_TOO_LONG);
 146         return 0;
 147     }
 148
 149     /* decrypt in place in 'rr->input' */
 150     rr->data = rr->input;
 151     rr->orig_len = rr->length;
 152
 153     if (rl->md_ctx != NULL) {
 154         const EVP_MD *tmpmd = EVP_MD_CTX_get0_md(rl->md_ctx);
 155
 156         if (tmpmd != NULL) {
 157             imac_size = EVP_MD_get_size(tmpmd);
 158             if (!ossl_assert(imac_size >= 0 && imac_size <= EVP_MAX_MD_SIZE)) {
 159                 RLAYERfatal(rl, SSL_AD_INTERNAL_ERROR, ERR_R_EVP_LIB);
 160                 return 0;
 161             }
 162             mac_size = (size_t)imac_size;
 163         }
 164     }
 165
 166     if (rl->use_etm && rl->md_ctx != NULL) {
 167         unsigned char *mac;
 168
 169         if (rr->orig_len < mac_size) {
 170             RLAYERfatal(rl, SSL_AD_DECODE_ERROR, SSL_R_LENGTH_TOO_SHORT);
 171             return 0;
 172         }
 173         rr->length -= mac_size;
 174         mac = rr->data + rr->length;
 175         i = rl->funcs->mac(rl, rr, md, 0 /* not send */);
 176         if (i == 0 || CRYPTO_memcmp(md, mac, (size_t)mac_size) != 0) {
 177             RLAYERfatal(rl, SSL_AD_BAD_RECORD_MAC,
 178                         SSL_R_DECRYPTION_FAILED_OR_BAD_RECORD_MAC);
 179             return 0;
 180         }
 181         /*
 182          * We've handled the mac now - there is no MAC inside the encrypted
 183          * record
 184          */
 185         mac_size = 0;
 186     }
 187
 188     /*
 189      * Set a mark around the packet decryption attempt.  This is DTLS, so
 190      * bad packets are just ignored, and we don't want to leave stray
 191      * errors in the queue from processing bogus junk that we ignored.
 192      */
 193     ERR_set_mark();
 194     enc_err = rl->funcs->cipher(rl, rr, 1, 0, &macbuf, mac_size);
 195
 196     /*-
 197      * enc_err is:
 198      *    0: if the record is publicly invalid, or an internal error, or AEAD
 199      *       decryption failed, or ETM decryption failed.
 200      *    1: Success or MTE decryption failed (MAC will be randomised)
 201      */
 202     if (enc_err == 0) {
 203         ERR_pop_to_mark();
 204         if (rl->alert != SSL_AD_NO_ALERT) {
 205             /* RLAYERfatal() already called */
 206             goto end;
 207         }
 208         /* For DTLS we simply ignore bad packets. */
 209         rr->length = 0;
 210         rl->packet_length = 0;
 211         goto end;
 212     }
 213     ERR_clear_last_mark();
 214     OSSL_TRACE_BEGIN(TLS) {
 215         BIO_printf(trc_out, "dec %zd\n", rr->length);
 216         BIO_dump_indent(trc_out, rr->data, rr->length, 4);
 217     } OSSL_TRACE_END(TLS);
 218
 219     /* r->length is now the compressed data plus mac */
 220     if (!rl->use_etm
 221             && (rl->enc_ctx != NULL)
 222             && (EVP_MD_CTX_get0_md(rl->md_ctx) != NULL)) {
 223         /* rl->md_ctx != NULL => mac_size != -1 */
 224
 225         i = rl->funcs->mac(rl, rr, md, 0 /* not send */);
 226         if (i == 0 || macbuf.mac == NULL
 227             || CRYPTO_memcmp(md, macbuf.mac, mac_size) != 0)
 228             enc_err = 0;
 229         if (rr->length > SSL3_RT_MAX_COMPRESSED_LENGTH + mac_size)
 230             enc_err = 0;
 231     }
 232
 233     if (enc_err == 0) {
 234         /* decryption failed, silently discard message */
 235         rr->length = 0;
 236         rl->packet_length = 0;
 237         goto end;
 238     }
 239
 240     /* r->length is now just compressed */
 241     if (rl->compctx != NULL) {
 242         if (rr->length > SSL3_RT_MAX_COMPRESSED_LENGTH) {
 243             RLAYERfatal(rl, SSL_AD_RECORD_OVERFLOW,
 244                         SSL_R_COMPRESSED_LENGTH_TOO_LONG);
 245             goto end;
 246         }
 247         if (!tls_do_uncompress(rl, rr)) {
 248             RLAYERfatal(rl, SSL_AD_DECOMPRESSION_FAILURE, SSL_R_BAD_DECOMPRESSION);
 249             goto end;
 250         }
 251     }
 252
 253     /*
 254      * Check if the received packet overflows the current Max Fragment
 255      * Length setting.
 256      */
 257     if (rr->length > rl->max_frag_len) {
 258         RLAYERfatal(rl, SSL_AD_RECORD_OVERFLOW, SSL_R_DATA_LENGTH_TOO_LONG);
 259         goto end;
 260     }
 261
 262     rr->off = 0;
 263     /*-
 264      * So at this point the following is true
 265      * ssl->s3.rrec.type   is the type of record
 266      * ssl->s3.rrec.length == number of bytes in record
 267      * ssl->s3.rrec.off    == offset to first valid byte
 268      * ssl->s3.rrec.data   == where to take bytes from, increment
 269      *                        after use :-).
 270      */
 271
 272     /* we have pulled in a full packet so zero things */
 273     rl->packet_length = 0;
 274
 275     /* Mark receipt of record. */
 276     dtls_record_bitmap_update(rl, bitmap);
 277
 278     ret = 1;
 279  end:
 280     if (macbuf.alloced)
 281         OPENSSL_free(macbuf.mac);
 282     return ret;
 283 }
 284
 285 static int dtls_rlayer_buffer_record(OSSL_RECORD_LAYER *rl, record_pqueue *queue,
 286                                      unsigned char *priority)
 287 {
 288     DTLS_RLAYER_RECORD_DATA *rdata;
 289     pitem *item;
 290
 291     /* Limit the size of the queue to prevent DOS attacks */
 292     if (pqueue_size(queue->q) >= 100)
 293         return 0;
 294
 295     rdata = OPENSSL_malloc(sizeof(*rdata));
 296     item = pitem_new(priority, rdata);
 297     if (rdata == NULL || item == NULL) {
 298         OPENSSL_free(rdata);
 299         pitem_free(item);
 300         RLAYERfatal(rl, SSL_AD_INTERNAL_ERROR, ERR_R_INTERNAL_ERROR);
 301         return -1;
 302     }
 303
 304     rdata->packet = rl->packet;
 305     rdata->packet_length = rl->packet_length;
 306     memcpy(&(rdata->rbuf), &rl->rbuf, sizeof(TLS_BUFFER));
 307     memcpy(&(rdata->rrec), &rl->rrec[0], sizeof(SSL3_RECORD));
 308
 309     item->data = rdata;
 310
 311     rl->packet = NULL;
 312     rl->packet_length = 0;
 313     memset(&rl->rbuf, 0, sizeof(TLS_BUFFER));
 314     memset(&rl->rrec[0], 0, sizeof(rl->rrec[0]));
 315
 316     if (!tls_setup_read_buffer(rl)) {
 317         /* RLAYERfatal() already called */
 318         OPENSSL_free(rdata->rbuf.buf);
 319         OPENSSL_free(rdata);
 320         pitem_free(item);
 321         return -1;
 322     }
 323
 324     if (pqueue_insert(queue->q, item) == NULL) {
 325         /* Must be a duplicate so ignore it */
 326         OPENSSL_free(rdata->rbuf.buf);
 327         OPENSSL_free(rdata);
 328         pitem_free(item);
 329     }
 330
 331     return 1;
 332 }
 333
 334 /* copy buffered record into OSSL_RECORD_LAYER structure */
 335 static int dtls_copy_rlayer_record(OSSL_RECORD_LAYER *rl, pitem *item)
 336 {
 337     DTLS_RLAYER_RECORD_DATA *rdata;
 338
 339     rdata = (DTLS_RLAYER_RECORD_DATA *)item->data;
 340
 341     ossl_tls_buffer_release(&rl->rbuf);
 342
 343     rl->packet = rdata->packet;
 344     rl->packet_length = rdata->packet_length;
 345     memcpy(&rl->rbuf, &(rdata->rbuf), sizeof(TLS_BUFFER));
 346     memcpy(&rl->rrec[0], &(rdata->rrec), sizeof(SSL3_RECORD));
 347
 348     /* Set proper sequence number for mac calculation */
 349     memcpy(&(rl->sequence[2]), &(rdata->packet[5]), 6);
 350
 351     return 1;
 352 }
 353
 354 static int dtls_retrieve_rlayer_buffered_record(OSSL_RECORD_LAYER *rl,
 355                                                 record_pqueue *queue)
 356 {
 357     pitem *item;
 358
 359     item = pqueue_pop(queue->q);
 360     if (item) {
 361         dtls_copy_rlayer_record(rl, item);
 362
 363         OPENSSL_free(item->data);
 364         pitem_free(item);
 365
 366         return 1;
 367     }
 368
 369     return 0;
 370 }
 371
 372 /*-
 373  * Call this to get a new input record.
 374  * It will return <= 0 if more data is needed, normally due to an error
 375  * or non-blocking IO.
 376  * When it finishes, one packet has been decoded and can be found in
 377  * ssl->s3.rrec.type    - is the type of record
 378  * ssl->s3.rrec.data    - data
 379  * ssl->s3.rrec.length  - number of bytes
 380  */
 381 int dtls_get_more_records(OSSL_RECORD_LAYER *rl)
 382 {
 383     int ssl_major, ssl_minor;
 384     int rret;
 385     size_t more, n;
 386     SSL3_RECORD *rr;
 387     unsigned char *p = NULL;
 388     unsigned short version;
 389     DTLS_BITMAP *bitmap;
 390     unsigned int is_next_epoch;
 391
 392     rl->num_recs = 0;
 393     rl->curr_rec = 0;
 394     rl->num_released = 0;
 395
 396     rr = rl->rrec;
 397
 398     if (rl->rbuf.buf == NULL) {
 399         if (!tls_setup_read_buffer(rl)) {
 400             /* RLAYERfatal() already called */
 401             return OSSL_RECORD_RETURN_FATAL;
 402         }
 403     }
 404
 405  again:
 406     /* if we're renegotiating, then there may be buffered records */
 407     if (dtls_retrieve_rlayer_buffered_record(rl, &rl->processed_rcds)) {
 408         rl->num_recs = 1;
 409         return OSSL_RECORD_RETURN_SUCCESS;
 410     }
 411
 412     /* get something from the wire */
 413
 414     /* check if we have the header */
 415     if ((rl->rstate != SSL_ST_READ_BODY) ||
 416         (rl->packet_length < DTLS1_RT_HEADER_LENGTH)) {
 417         rret = rl->funcs->read_n(rl, DTLS1_RT_HEADER_LENGTH,
 418                                  TLS_BUFFER_get_len(&rl->rbuf), 0, 1, &n);
 419         /* read timeout is handled by dtls1_read_bytes */
 420         if (rret < OSSL_RECORD_RETURN_SUCCESS) {
 421             /* RLAYERfatal() already called if appropriate */
 422             return rret;         /* error or non-blocking */
 423         }
 424
 425         /* this packet contained a partial record, dump it */
 426         if (rl->packet_length != DTLS1_RT_HEADER_LENGTH) {
 427             rl->packet_length = 0;
 428             goto again;
 429         }
 430
 431         rl->rstate = SSL_ST_READ_BODY;
 432
 433         p = rl->packet;
 434
 435         if (rl->msg_callback != NULL)
 436             rl->msg_callback(0, 0, SSL3_RT_HEADER, p, DTLS1_RT_HEADER_LENGTH,
 437                             rl->cbarg);
 438
 439         /* Pull apart the header into the DTLS1_RECORD */
 440         rr->type = *(p++);
 441         ssl_major = *(p++);
 442         ssl_minor = *(p++);
 443         version = (ssl_major << 8) | ssl_minor;
 444
 445         /* sequence number is 64 bits, with top 2 bytes = epoch */
 446         n2s(p, rr->epoch);
 447
 448         memcpy(&(rl->sequence[2]), p, 6);
 449         p += 6;
 450
 451         n2s(p, rr->length);
 452
 453         /*
 454          * Lets check the version. We tolerate alerts that don't have the exact
 455          * version number (e.g. because of protocol version errors)
 456          */
 457         if (!rl->is_first_record && rr->type != SSL3_RT_ALERT) {
 458             if (version != rl->version) {
 459                 /* unexpected version, silently discard */
 460                 rr->length = 0;
 461                 rl->packet_length = 0;
 462                 goto again;
 463             }
 464         }
 465
 466         if (ssl_major !=
 467                 (rl->version == DTLS_ANY_VERSION ? DTLS1_VERSION_MAJOR
 468                                                  : rl->version >> 8)) {
 469             /* wrong version, silently discard record */
 470             rr->length = 0;
 471             rl->packet_length = 0;
 472             goto again;
 473         }
 474
 475         if (rr->length > SSL3_RT_MAX_ENCRYPTED_LENGTH) {
 476             /* record too long, silently discard it */
 477             rr->length = 0;
 478             rl->packet_length = 0;
 479             goto again;
 480         }
 481
 482         /*
 483          * If received packet overflows maximum possible fragment length then
 484          * silently discard it
 485          */
 486         if (rr->length > rl->max_frag_len + SSL3_RT_MAX_ENCRYPTED_OVERHEAD) {
 487             /* record too long, silently discard it */
 488             rr->length = 0;
 489             rl->packet_length = 0;
 490             goto again;
 491         }
 492
 493         /* now rl->rstate == SSL_ST_READ_BODY */
 494     }
 495
 496     /* rl->rstate == SSL_ST_READ_BODY, get and decode the data */
 497
 498     if (rr->length > rl->packet_length - DTLS1_RT_HEADER_LENGTH) {
 499         /* now rl->packet_length == DTLS1_RT_HEADER_LENGTH */
 500         more = rr->length;
 501         rret = rl->funcs->read_n(rl, more, more, 1, 1, &n);
 502         /* this packet contained a partial record, dump it */
 503         if (rret < OSSL_RECORD_RETURN_SUCCESS || n != more) {
 504             if (rl->alert != SSL_AD_NO_ALERT) {
 505                 /* read_n() called RLAYERfatal() */
 506                 return OSSL_RECORD_RETURN_FATAL;
 507             }
 508             rr->length = 0;
 509             rl->packet_length = 0;
 510             goto again;
 511         }
 512
 513         /*
 514          * now n == rr->length,
 515          * and rl->packet_length ==  DTLS1_RT_HEADER_LENGTH + rr->length
 516          */
 517     }
 518     /* set state for later operations */
 519     rl->rstate = SSL_ST_READ_HEADER;
 520
 521     /* match epochs.  NULL means the packet is dropped on the floor */
 522     bitmap = dtls_get_bitmap(rl, rr, &is_next_epoch);
 523     if (bitmap == NULL) {
 524         rr->length = 0;
 525         rl->packet_length = 0; /* dump this record */
 526         goto again;             /* get another record */
 527     }
 528 #ifndef OPENSSL_NO_SCTP
 529     /* Only do replay check if no SCTP bio */
 530     if (!BIO_dgram_is_sctp(rl->bio)) {
 531 #endif
 532         /* Check whether this is a repeat, or aged record. */
 533         if (!dtls_record_replay_check(rl, bitmap)) {
 534             rr->length = 0;
 535             rl->packet_length = 0; /* dump this record */
 536             goto again;         /* get another record */
 537         }
 538 #ifndef OPENSSL_NO_SCTP
 539     }
 540 #endif
 541
 542     /* just read a 0 length packet */
 543     if (rr->length == 0)
 544         goto again;
 545
 546     /*
 547      * If this record is from the next epoch (either HM or ALERT), and a
 548      * handshake is currently in progress, buffer it since it cannot be
 549      * processed at this time.
 550      */
 551     if (is_next_epoch) {
 552         if (rl->in_init) {
 553             if (dtls_rlayer_buffer_record(rl, &(rl->unprocessed_rcds),
 554                                           rr->seq_num) < 0) {
 555                 /* RLAYERfatal() already called */
 556                 return OSSL_RECORD_RETURN_FATAL;
 557             }
 558         }
 559         rr->length = 0;
 560         rl->packet_length = 0;
 561         goto again;
 562     }
 563
 564     if (!dtls_process_record(rl, bitmap)) {
 565         if (rl->alert != SSL_AD_NO_ALERT) {
 566             /* dtls_process_record() called RLAYERfatal */
 567             return OSSL_RECORD_RETURN_FATAL;
 568         }
 569         rr->length = 0;
 570         rl->packet_length = 0; /* dump this record */
 571         goto again;             /* get another record */
 572     }
 573
 574     rl->num_recs = 1;
 575     return OSSL_RECORD_RETURN_SUCCESS;
 576 }
 577
 578 static int dtls_free(OSSL_RECORD_LAYER *rl)
 579 {
 580     TLS_BUFFER *rbuf;
 581     size_t left, written;
 582     pitem *item;
 583     DTLS_RLAYER_RECORD_DATA *rdata;
 584     int ret = 1;
 585
 586     rbuf = &rl->rbuf;
 587
 588     left = rbuf->left;
 589     if (left > 0) {
 590         /*
 591          * This record layer is closing but we still have data left in our
 592          * buffer. It must be destined for the next epoch - so push it there.
 593          */
 594         ret = BIO_write_ex(rl->next, rbuf->buf + rbuf->offset, left, &written);
 595         rbuf->left = 0;
 596     }
 597
 598     if (rl->unprocessed_rcds.q != NULL) {
 599         while ((item = pqueue_pop(rl->unprocessed_rcds.q)) != NULL) {
 600             rdata = (DTLS_RLAYER_RECORD_DATA *)item->data;
 601             /* Push to the next record layer */
 602             ret &= BIO_write_ex(rl->next, rdata->packet, rdata->packet_length,
 603                                 &written);
 604             OPENSSL_free(rdata->rbuf.buf);
 605             OPENSSL_free(item->data);
 606             pitem_free(item);
 607         }
 608         pqueue_free(rl->unprocessed_rcds.q);
 609     }
 610
 611     if (rl->processed_rcds.q != NULL) {
 612         while ((item = pqueue_pop(rl->processed_rcds.q)) != NULL) {
 613             rdata = (DTLS_RLAYER_RECORD_DATA *)item->data;
 614             OPENSSL_free(rdata->rbuf.buf);
 615             OPENSSL_free(item->data);
 616             pitem_free(item);
 617         }
 618         pqueue_free(rl->processed_rcds.q);
 619     }
 620
 621     return tls_free(rl) && ret;
 622 }
 623
 624 static int
 625 dtls_new_record_layer(OSSL_LIB_CTX *libctx, const char *propq, int vers,
 626                       int role, int direction, int level, uint16_t epoch,
 627                       unsigned char *key, size_t keylen, unsigned char *iv,
 628                       size_t ivlen, unsigned char *mackey, size_t mackeylen,
 629                       const EVP_CIPHER *ciph, size_t taglen,
 630                       int mactype,
 631                       const EVP_MD *md, COMP_METHOD *comp, BIO *prev,
 632                       BIO *transport, BIO *next, BIO_ADDR *local, BIO_ADDR *peer,
 633                       const OSSL_PARAM *settings, const OSSL_PARAM *options,
 634                       const OSSL_DISPATCH *fns, void *cbarg,
 635                       OSSL_RECORD_LAYER **retrl)
 636 {
 637     int ret;
 638
 639     ret = tls_int_new_record_layer(libctx, propq, vers, role, direction, level,
 640                                    key, keylen, iv, ivlen, mackey, mackeylen,
 641                                    ciph, taglen, mactype, md, comp, prev,
 642                                    transport, next, local, peer, settings,
 643                                    options, fns, cbarg, retrl);
 644
 645     if (ret != OSSL_RECORD_RETURN_SUCCESS)
 646         return ret;
 647
 648     (*retrl)->unprocessed_rcds.q = pqueue_new();
 649     (*retrl)->processed_rcds.q = pqueue_new();
 650     if ((*retrl)->unprocessed_rcds.q == NULL
 651             || (*retrl)->processed_rcds.q == NULL) {
 652         dtls_free(*retrl);
 653         *retrl = NULL;
 654         ERR_raise(ERR_LIB_SSL, ERR_R_SSL_LIB);
 655         return OSSL_RECORD_RETURN_FATAL;
 656     }
 657
 658     (*retrl)->unprocessed_rcds.epoch = epoch + 1;
 659     (*retrl)->processed_rcds.epoch = epoch;
 660
 661     (*retrl)->isdtls = 1;
 662     (*retrl)->epoch = epoch;
 663     (*retrl)->in_init = 1;
 664
 665     switch (vers) {
 666     case DTLS_ANY_VERSION:
 667         (*retrl)->funcs = &dtls_any_funcs;
 668         break;
 669     case DTLS1_2_VERSION:
 670     case DTLS1_VERSION:
 671     case DTLS1_BAD_VER:
 672         (*retrl)->funcs = &dtls_1_funcs;
 673         break;
 674     default:
 675         /* Should not happen */
 676         ERR_raise(ERR_LIB_SSL, ERR_R_INTERNAL_ERROR);
 677         ret = OSSL_RECORD_RETURN_FATAL;
 678         goto err;
 679     }
 680
 681     ret = (*retrl)->funcs->set_crypto_state(*retrl, level, key, keylen, iv,
 682                                             ivlen, mackey, mackeylen, ciph,
 683                                             taglen, mactype, md, comp);
 684
 685  err:
 686     if (ret != OSSL_RECORD_RETURN_SUCCESS) {
 687         OPENSSL_free(*retrl);
 688         *retrl = NULL;
 689     }
 690     return ret;
 691 }
 692
 693 int dtls_prepare_record_header(OSSL_RECORD_LAYER *rl,
 694                                WPACKET *thispkt,
 695                                OSSL_RECORD_TEMPLATE *templ,
 696                                unsigned int rectype,
 697                                unsigned char **recdata)
 698 {
 699     size_t maxcomplen;
 700
 701     *recdata = NULL;
 702
 703     maxcomplen = templ->buflen;
 704     if (rl->compctx != NULL)
 705         maxcomplen += SSL3_RT_MAX_COMPRESSED_OVERHEAD;
 706
 707     if (!WPACKET_put_bytes_u8(thispkt, rectype)
 708             || !WPACKET_put_bytes_u16(thispkt, templ->version)
 709             || !WPACKET_put_bytes_u16(thispkt, rl->epoch)
 710             || !WPACKET_memcpy(thispkt, &(rl->sequence[2]), 6)
 711             || !WPACKET_start_sub_packet_u16(thispkt)
 712             || (rl->eivlen > 0
 713                 && !WPACKET_allocate_bytes(thispkt, rl->eivlen, NULL))
 714             || (maxcomplen > 0
 715                 && !WPACKET_reserve_bytes(thispkt, maxcomplen,
 716                                           recdata))) {
 717         RLAYERfatal(rl, SSL_AD_INTERNAL_ERROR, ERR_R_INTERNAL_ERROR);
 718         return 0;
 719     }
 720
 721     return 1;
 722 }
 723
 724 int dtls_post_encryption_processing(OSSL_RECORD_LAYER *rl,
 725                                     size_t mac_size,
 726                                     OSSL_RECORD_TEMPLATE *thistempl,
 727                                     WPACKET *thispkt,
 728                                     SSL3_RECORD *thiswr)
 729 {
 730     if (!tls_post_encryption_processing_default(rl, mac_size, thistempl,
 731                                                 thispkt, thiswr)) {
 732         /* RLAYERfatal() already called */
 733         return 0;
 734     }
 735
 736     return tls_increment_sequence_ctr(rl);
 737 }
 738
 739 static size_t dtls_get_max_record_overhead(OSSL_RECORD_LAYER *rl)
 740 {
 741     size_t blocksize = 0;
 742
 743     if (rl->enc_ctx != NULL &&
 744         (EVP_CIPHER_CTX_get_mode(rl->enc_ctx) == EVP_CIPH_CBC_MODE))
 745         blocksize = EVP_CIPHER_CTX_get_block_size(rl->enc_ctx);
 746
 747     /*
 748      * If we have a cipher in place then the tag is mandatory. If the cipher is
 749      * CBC mode then an explicit IV is also mandatory. If we know the digest,
 750      * then we check it is consistent with the taglen. In the case of stitched
 751      * ciphers or AEAD ciphers we don't now the digest (or there isn't one) so
 752      * we just trust that the taglen is correct.
 753      */
 754     assert(rl->enc_ctx == NULL  || ((blocksize == 0 || rl->eivlen > 0)
 755                                     && rl->taglen > 0));
 756     assert(rl->md == NULL || (int)rl->taglen == EVP_MD_size(rl->md));
 757
 758     /*
 759      * Record overhead consists of the record header, the explicit IV, any
 760      * expansion due to cbc padding, and the mac/tag len. There could be
 761      * further expansion due to compression - but we don't know what this will
 762      * be without knowing the length of the data. However when this function is
 763      * called we don't know what the length will be yet - so this is a catch-22.
 764      * We *could* use SSL_3_RT_MAX_COMPRESSED_OVERHEAD which is an upper limit
 765      * for the maximum record size. But this value is larger than our fallback
 766      * MTU size - so isn't very helpful. We just ignore potential expansion
 767      * due to compression.
 768      */
 769     return DTLS1_RT_HEADER_LENGTH + rl->eivlen + blocksize + rl->taglen;
 770 }
 771
 772 const OSSL_RECORD_METHOD ossl_dtls_record_method = {
 773     dtls_new_record_layer,
 774     dtls_free,
 775     tls_reset,
 776     tls_unprocessed_read_pending,
 777     tls_processed_read_pending,
 778     tls_app_data_pending,
 779     tls_get_max_records,
 780     tls_write_records,
 781     tls_retry_write_records,
 782     tls_read_record,
 783     tls_release_record,
 784     tls_get_alert_code,
 785     tls_set1_bio,
 786     tls_set_protocol_version,
 787     NULL,
 788     tls_set_first_handshake,
 789     tls_set_max_pipelines,
 790     dtls_set_in_init,
 791     tls_get_state,
 792     tls_set_options,
 793     tls_get_compression,
 794     tls_set_max_frag_len,
 795     dtls_get_max_record_overhead,
 796     tls_increment_sequence_ctr,
 797     tls_alloc_buffers,
 798     tls_free_buffers
 799 };