wbrawner/openssl
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions
openssl/ssl/d1_pkt.c
Matt Caswell cfd40fd39e Prevent DTLS Finished message injection 
Follow on from CVE-2016-2179

The investigation and analysis of CVE-2016-2179 highlighted a related flaw.

This commit fixes a security "near miss" in the buffered message handling
code. Ultimately this is not currently believed to be exploitable due to
the reasons outlined below, and therefore there is no CVE for this on its
own.

The issue this commit fixes is a MITM attack where the attacker can inject
a Finished message into the handshake. In the description below it is
assumed that the attacker injects the Finished message for the server to
receive it. The attack could work equally well the other way around (i.e
where the client receives the injected Finished message).

The MITM requires the following capabilities:
- The ability to manipulate the MTU that the client selects such that it
is small enough for the client to fragment Finished messages.
- The ability to selectively drop and modify records sent from the client
- The ability to inject its own records and send them to the server

The MITM forces the client to select a small MTU such that the client
will fragment the Finished message. Ideally for the attacker the first
fragment will contain all but the last byte of the Finished message,
with the second fragment containing the final byte.

During the handshake and prior to the client sending the CCS the MITM
injects a plaintext Finished message fragment to the server containing
all but the final byte of the Finished message. The message sequence
number should be the one expected to be used for the real Finished message.

OpenSSL will recognise that the received fragment is for the future and
will buffer it for later use.

After the client sends the CCS it then sends its own Finished message in
two fragments. The MITM causes the first of these fragments to be
dropped. The OpenSSL server will then receive the second of the fragments
and reassemble the complete Finished message consisting of the MITM
fragment and the final byte from the real client.

The advantage to the attacker in injecting a Finished message is that
this provides the capability to modify other handshake messages (e.g.
the ClientHello) undetected. A difficulty for the attacker is knowing in
advance what impact any of those changes might have on the final byte of
the handshake hash that is going to be sent in the "real" Finished
message. In the worst case for the attacker this means that only 1 in
256 of such injection attempts will succeed.

It may be possible in some situations for the attacker to improve this such
that all attempts succeed. For example if the handshake includes client
authentication then the final message flight sent by the client will
include a Certificate. Certificates are ASN.1 objects where the signed
portion is DER encoded. The non-signed portion could be BER encoded and so
the attacker could re-encode the certificate such that the hash for the
whole handshake comes to a different value. The certificate re-encoding
would not be detectable because only the non-signed portion is changed. As
this is the final flight of messages sent from the client the attacker
knows what the complete hanshake hash value will be that the client will
send - and therefore knows what the final byte will be. Through a process
of trial and error the attacker can re-encode the certificate until the
modified handhshake also has a hash with the same final byte. This means
that when the Finished message is verified by the server it will be
correct in all cases.

In practice the MITM would need to be able to perform the same attack
against both the client and the server. If the attack is only performed
against the server (say) then the server will not detect the modified
handshake, but the client will and will abort the connection.
Fortunately, although OpenSSL is vulnerable to Finished message
injection, it is not vulnerable if *both* client and server are OpenSSL.
The reason is that OpenSSL has a hard "floor" for a minimum MTU size
that it will never go below. This minimum means that a Finished message
will never be sent in a fragmented form and therefore the MITM does not
have one of its pre-requisites. Therefore this could only be exploited
if using OpenSSL and some other DTLS peer that had its own and separate
Finished message injection flaw.

The fix is to ensure buffered messages are cleared on epoch change.

Reviewed-by: Richard Levitte <levitte@openssl.org>
2016-08-22 11:03:14 +01:00

1967 lines
63 KiB
C
Raw Blame History

/* ssl/d1_pkt.c */
/*
* DTLS implementation written by Nagendra Modadugu
* (nagendra@cs.stanford.edu) for the OpenSSL project 2005.
*/
/* ====================================================================
* Copyright (c) 1998-2005 The OpenSSL Project. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. All advertising materials mentioning features or use of this
* software must display the following acknowledgment:
* "This product includes software developed by the OpenSSL Project
* for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
*
* 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
* endorse or promote products derived from this software without
* prior written permission. For written permission, please contact
* openssl-core@openssl.org.
*
* 5. Products derived from this software may not be called "OpenSSL"
* nor may "OpenSSL" appear in their names without prior written
* permission of the OpenSSL Project.
*
* 6. Redistributions of any form whatsoever must retain the following
* acknowledgment:
* "This product includes software developed by the OpenSSL Project
* for use in the OpenSSL Toolkit (http://www.openssl.org/)"
*
* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
* EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
* ====================================================================
*
* This product includes cryptographic software written by Eric Young
* (eay@cryptsoft.com). This product includes software written by Tim
* Hudson (tjh@cryptsoft.com).
*
*/
/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
* All rights reserved.
*
* This package is an SSL implementation written
* by Eric Young (eay@cryptsoft.com).
* The implementation was written so as to conform with Netscapes SSL.
*
* This library is free for commercial and non-commercial use as long as
* the following conditions are aheared to. The following conditions
* apply to all code found in this distribution, be it the RC4, RSA,
* lhash, DES, etc., code; not just the SSL code. The SSL documentation
* included with this distribution is covered by the same copyright terms
* except that the holder is Tim Hudson (tjh@cryptsoft.com).
*
* Copyright remains Eric Young's, and as such any Copyright notices in
* the code are not to be removed.
* If this package is used in a product, Eric Young should be given attribution
* as the author of the parts of the library used.
* This can be in the form of a textual message at program startup or
* in documentation (online or textual) provided with the package.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* "This product includes cryptographic software written by
* Eric Young (eay@cryptsoft.com)"
* The word 'cryptographic' can be left out if the rouines from the library
* being used are not cryptographic related :-).
* 4. If you include any Windows specific code (or a derivative thereof) from
* the apps directory (application code) you must include an acknowledgement:
* "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
*
* THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* The licence and distribution terms for any publically available version or
* derivative of this code cannot be changed. i.e. this code cannot simply be
* copied and put under another distribution licence
* [including the GNU Public Licence.]
*/
#include <stdio.h>
#include <errno.h>
#define USE_SOCKETS
#include "ssl_locl.h"
#include <openssl/evp.h>
#include <openssl/buffer.h>
#include <openssl/pqueue.h>
#include <openssl/rand.h>
/* mod 128 saturating subtract of two 64-bit values in big-endian order */
static int satsub64be(const unsigned char *v1, const unsigned char *v2)
{
int ret, sat, brw, i;
if (sizeof(long) == 8)
do {
const union {
long one;
char little;
} is_endian = {
1
};
long l;
if (is_endian.little)
break;
/* not reached on little-endians */
/*
* following test is redundant, because input is always aligned,
* but I take no chances...
*/
if (((size_t)v1 | (size_t)v2) & 0x7)
break;
l = *((long *)v1);
l -= *((long *)v2);
if (l > 128)
return 128;
else if (l < -128)
return -128;
else
return (int)l;
} while (0);
ret = (int)v1[7] - (int)v2[7];
sat = 0;
brw = ret >> 8; /* brw is either 0 or -1 */
if (ret & 0x80) {
for (i = 6; i >= 0; i--) {
brw += (int)v1[i] - (int)v2[i];
sat |= ~brw;
brw >>= 8;
}
} else {
for (i = 6; i >= 0; i--) {
brw += (int)v1[i] - (int)v2[i];
sat |= brw;
brw >>= 8;
}
}
brw <<= 8; /* brw is either 0 or -256 */
if (sat & 0xff)
return brw | 0x80;
else
return brw + (ret & 0xFF);
}
static int have_handshake_fragment(SSL *s, int type, unsigned char *buf,
int len, int peek);
static int dtls1_record_replay_check(SSL *s, DTLS1_BITMAP *bitmap);
static void dtls1_record_bitmap_update(SSL *s, DTLS1_BITMAP *bitmap);
static DTLS1_BITMAP *dtls1_get_bitmap(SSL *s, SSL3_RECORD *rr,
unsigned int *is_next_epoch);
#if 0
static int dtls1_record_needs_buffering(SSL *s, SSL3_RECORD *rr,
unsigned short *priority,
unsigned long *offset);
#endif
static int dtls1_buffer_record(SSL *s, record_pqueue *q,
unsigned char *priority);
static int dtls1_process_record(SSL *s, DTLS1_BITMAP *bitmap);
/* copy buffered record into SSL structure */
static int dtls1_copy_record(SSL *s, pitem *item)
{
DTLS1_RECORD_DATA *rdata;
rdata = (DTLS1_RECORD_DATA *)item->data;
if (s->s3->rbuf.buf != NULL)
OPENSSL_free(s->s3->rbuf.buf);
s->packet = rdata->packet;
s->packet_length = rdata->packet_length;
memcpy(&(s->s3->rbuf), &(rdata->rbuf), sizeof(SSL3_BUFFER));
memcpy(&(s->s3->rrec), &(rdata->rrec), sizeof(SSL3_RECORD));
/* Set proper sequence number for mac calculation */
memcpy(&(s->s3->read_sequence[2]), &(rdata->packet[5]), 6);
return (1);
}
static int
dtls1_buffer_record(SSL *s, record_pqueue *queue, unsigned char *priority)
{
DTLS1_RECORD_DATA *rdata;
pitem *item;
/* Limit the size of the queue to prevent DOS attacks */
if (pqueue_size(queue->q) >= 100)
return 0;
rdata = OPENSSL_malloc(sizeof(DTLS1_RECORD_DATA));
item = pitem_new(priority, rdata);
if (rdata == NULL || item == NULL) {
if (rdata != NULL)
OPENSSL_free(rdata);
if (item != NULL)
pitem_free(item);
SSLerr(SSL_F_DTLS1_BUFFER_RECORD, ERR_R_INTERNAL_ERROR);
return -1;
}
rdata->packet = s->packet;
rdata->packet_length = s->packet_length;
memcpy(&(rdata->rbuf), &(s->s3->rbuf), sizeof(SSL3_BUFFER));
memcpy(&(rdata->rrec), &(s->s3->rrec), sizeof(SSL3_RECORD));
item->data = rdata;
#ifndef OPENSSL_NO_SCTP
/* Store bio_dgram_sctp_rcvinfo struct */
if (BIO_dgram_is_sctp(SSL_get_rbio(s)) &&
(s->state == SSL3_ST_SR_FINISHED_A
|| s->state == SSL3_ST_CR_FINISHED_A)) {
BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SCTP_GET_RCVINFO,
sizeof(rdata->recordinfo), &rdata->recordinfo);
}
#endif
s->packet = NULL;
s->packet_length = 0;
memset(&(s->s3->rbuf), 0, sizeof(SSL3_BUFFER));
memset(&(s->s3->rrec), 0, sizeof(SSL3_RECORD));
if (!ssl3_setup_buffers(s)) {
SSLerr(SSL_F_DTLS1_BUFFER_RECORD, ERR_R_INTERNAL_ERROR);
if (rdata->rbuf.buf != NULL)
OPENSSL_free(rdata->rbuf.buf);
OPENSSL_free(rdata);
pitem_free(item);
return (-1);
}
/* insert should not fail, since duplicates are dropped */
if (pqueue_insert(queue->q, item) == NULL) {
SSLerr(SSL_F_DTLS1_BUFFER_RECORD, ERR_R_INTERNAL_ERROR);
if (rdata->rbuf.buf != NULL)
OPENSSL_free(rdata->rbuf.buf);
OPENSSL_free(rdata);
pitem_free(item);
return (-1);
}
return (1);
}
static int dtls1_retrieve_buffered_record(SSL *s, record_pqueue *queue)
{
pitem *item;
item = pqueue_pop(queue->q);
if (item) {
dtls1_copy_record(s, item);
OPENSSL_free(item->data);
pitem_free(item);
return (1);
}
return (0);
}
/*
* retrieve a buffered record that belongs to the new epoch, i.e., not
* processed yet
*/
#define dtls1_get_unprocessed_record(s) \
dtls1_retrieve_buffered_record((s), \
&((s)->d1->unprocessed_rcds))
/*
* retrieve a buffered record that belongs to the current epoch, ie,
* processed
*/
#define dtls1_get_processed_record(s) \
dtls1_retrieve_buffered_record((s), \
&((s)->d1->processed_rcds))
static int dtls1_process_buffered_records(SSL *s)
{
pitem *item;
SSL3_BUFFER *rb;
SSL3_RECORD *rr;
DTLS1_BITMAP *bitmap;
unsigned int is_next_epoch;
int replayok = 1;
item = pqueue_peek(s->d1->unprocessed_rcds.q);
if (item) {
/* Check if epoch is current. */
if (s->d1->unprocessed_rcds.epoch != s->d1->r_epoch)
return 1; /* Nothing to do. */
rr = &s->s3->rrec;
rb = &s->s3->rbuf;
if (rb->left > 0) {
/*
* We've still got data from the current packet to read. There could
* be a record from the new epoch in it - so don't overwrite it
* with the unprocessed records yet (we'll do it when we've
* finished reading the current packet).
*/
return 1;
}
/* Process all the records. */
while (pqueue_peek(s->d1->unprocessed_rcds.q)) {
dtls1_get_unprocessed_record(s);
bitmap = dtls1_get_bitmap(s, rr, &is_next_epoch);
if (bitmap == NULL) {
/*
* Should not happen. This will only ever be NULL when the
* current record is from a different epoch. But that cannot
* be the case because we already checked the epoch above
*/
SSLerr(SSL_F_DTLS1_PROCESS_BUFFERED_RECORDS,
ERR_R_INTERNAL_ERROR);
return 0;
}
#ifndef OPENSSL_NO_SCTP
/* Only do replay check if no SCTP bio */
if (!BIO_dgram_is_sctp(SSL_get_rbio(s)))
#endif
{
/*
* Check whether this is a repeat, or aged record. We did this
* check once already when we first received the record - but
* we might have updated the window since then due to
* records we subsequently processed.
*/
replayok = dtls1_record_replay_check(s, bitmap);
}
if (!replayok || !dtls1_process_record(s, bitmap)) {
/* dump this record */
rr->length = 0;
s->packet_length = 0;
continue;
}
if (dtls1_buffer_record(s, &(s->d1->processed_rcds),
s->s3->rrec.seq_num) < 0)
return 0;
}
}
/*
* sync epoch numbers once all the unprocessed records have been
* processed
*/
s->d1->processed_rcds.epoch = s->d1->r_epoch;
s->d1->unprocessed_rcds.epoch = s->d1->r_epoch + 1;
return 1;
}
#if 0
static int dtls1_get_buffered_record(SSL *s)
{
pitem *item;
PQ_64BIT priority =
(((PQ_64BIT) s->d1->handshake_read_seq) << 32) |
((PQ_64BIT) s->d1->r_msg_hdr.frag_off);
/* if we're not (re)negotiating, nothing buffered */
if (!SSL_in_init(s))
return 0;
item = pqueue_peek(s->d1->rcvd_records);
if (item && item->priority == priority) {
/*
* Check if we've received the record of interest. It must be a
* handshake record, since data records as passed up without
* buffering
*/
DTLS1_RECORD_DATA *rdata;
item = pqueue_pop(s->d1->rcvd_records);
rdata = (DTLS1_RECORD_DATA *)item->data;
if (s->s3->rbuf.buf != NULL)
OPENSSL_free(s->s3->rbuf.buf);
s->packet = rdata->packet;
s->packet_length = rdata->packet_length;
memcpy(&(s->s3->rbuf), &(rdata->rbuf), sizeof(SSL3_BUFFER));
memcpy(&(s->s3->rrec), &(rdata->rrec), sizeof(SSL3_RECORD));
OPENSSL_free(item->data);
pitem_free(item);
/* s->d1->next_expected_seq_num++; */
return (1);
}
return 0;
}
#endif
static int dtls1_process_record(SSL *s, DTLS1_BITMAP *bitmap)
{
int i, al;
int enc_err;
SSL_SESSION *sess;
SSL3_RECORD *rr;
unsigned int mac_size, orig_len;
unsigned char md[EVP_MAX_MD_SIZE];
rr = &(s->s3->rrec);
sess = s->session;
/*
* At this point, s->packet_length == SSL3_RT_HEADER_LNGTH + rr->length,
* and we have that many bytes in s->packet
*/
rr->input = &(s->packet[DTLS1_RT_HEADER_LENGTH]);
/*
* ok, we can now read from 's->packet' data into 'rr' rr->input points
* at rr->length bytes, which need to be copied into rr->data by either
* the decryption or by the decompression When the data is 'copied' into
* the rr->data buffer, rr->input will be pointed at the new buffer
*/
/*
* We now have - encrypted [ MAC [ compressed [ plain ] ] ] rr->length
* bytes of encrypted compressed stuff.
*/
/* check is not needed I believe */
if (rr->length > SSL3_RT_MAX_ENCRYPTED_LENGTH) {
al = SSL_AD_RECORD_OVERFLOW;
SSLerr(SSL_F_DTLS1_PROCESS_RECORD, SSL_R_ENCRYPTED_LENGTH_TOO_LONG);
goto f_err;
}
/* decrypt in place in 'rr->input' */
rr->data = rr->input;
enc_err = s->method->ssl3_enc->enc(s, 0);
/*-
* enc_err is:
* 0: (in non-constant time) if the record is publically invalid.
* 1: if the padding is valid
* -1: if the padding is invalid
*/
if (enc_err == 0) {
/* For DTLS we simply ignore bad packets. */
rr->length = 0;
s->packet_length = 0;
goto err;
}
#ifdef TLS_DEBUG
printf("dec %d\n", rr->length);
{
unsigned int z;
for (z = 0; z < rr->length; z++)
printf("%02X%c", rr->data[z], ((z + 1) % 16) ? ' ' : '\n');
}
printf("\n");
#endif
/* r->length is now the compressed data plus mac */
if ((sess != NULL) &&
(s->enc_read_ctx != NULL) && (EVP_MD_CTX_md(s->read_hash) != NULL)) {
/* s->read_hash != NULL => mac_size != -1 */
unsigned char *mac = NULL;
unsigned char mac_tmp[EVP_MAX_MD_SIZE];
mac_size = EVP_MD_CTX_size(s->read_hash);
OPENSSL_assert(mac_size <= EVP_MAX_MD_SIZE);
/*
* kludge: *_cbc_remove_padding passes padding length in rr->type
*/
orig_len = rr->length + ((unsigned int)rr->type >> 8);
/*
* orig_len is the length of the record before any padding was
* removed. This is public information, as is the MAC in use,
* therefore we can safely process the record in a different amount
* of time if it's too short to possibly contain a MAC.
*/
if (orig_len < mac_size ||
/* CBC records must have a padding length byte too. */
(EVP_CIPHER_CTX_mode(s->enc_read_ctx) == EVP_CIPH_CBC_MODE &&
orig_len < mac_size + 1)) {
al = SSL_AD_DECODE_ERROR;
SSLerr(SSL_F_DTLS1_PROCESS_RECORD, SSL_R_LENGTH_TOO_SHORT);
goto f_err;
}
if (EVP_CIPHER_CTX_mode(s->enc_read_ctx) == EVP_CIPH_CBC_MODE) {
/*
* We update the length so that the TLS header bytes can be
* constructed correctly but we need to extract the MAC in
* constant time from within the record, without leaking the
* contents of the padding bytes.
*/
mac = mac_tmp;
ssl3_cbc_copy_mac(mac_tmp, rr, mac_size, orig_len);
rr->length -= mac_size;
} else {
/*
* In this case there's no padding, so |orig_len| equals
* |rec->length| and we checked that there's enough bytes for
* |mac_size| above.
*/
rr->length -= mac_size;
mac = &rr->data[rr->length];
}
i = s->method->ssl3_enc->mac(s, md, 0 /* not send */ );
if (i < 0 || mac == NULL
|| CRYPTO_memcmp(md, mac, (size_t)mac_size) != 0)
enc_err = -1;
if (rr->length > SSL3_RT_MAX_COMPRESSED_LENGTH + mac_size)
enc_err = -1;
}
if (enc_err < 0) {
/* decryption failed, silently discard message */
rr->length = 0;
s->packet_length = 0;
goto err;
}
/* r->length is now just compressed */
if (s->expand != NULL) {
if (rr->length > SSL3_RT_MAX_COMPRESSED_LENGTH) {
al = SSL_AD_RECORD_OVERFLOW;
SSLerr(SSL_F_DTLS1_PROCESS_RECORD,
SSL_R_COMPRESSED_LENGTH_TOO_LONG);
goto f_err;
}
if (!ssl3_do_uncompress(s)) {
al = SSL_AD_DECOMPRESSION_FAILURE;
SSLerr(SSL_F_DTLS1_PROCESS_RECORD, SSL_R_BAD_DECOMPRESSION);
goto f_err;
}
}
if (rr->length > SSL3_RT_MAX_PLAIN_LENGTH) {
al = SSL_AD_RECORD_OVERFLOW;
SSLerr(SSL_F_DTLS1_PROCESS_RECORD, SSL_R_DATA_LENGTH_TOO_LONG);
goto f_err;
}
rr->off = 0;
/*-
* So at this point the following is true
* ssl->s3->rrec.type is the type of record
* ssl->s3->rrec.length == number of bytes in record
* ssl->s3->rrec.off == offset to first valid byte
* ssl->s3->rrec.data == where to take bytes from, increment
* after use :-).
*/
/* we have pulled in a full packet so zero things */
s->packet_length = 0;
/* Mark receipt of record. */
dtls1_record_bitmap_update(s, bitmap);
return (1);
f_err:
ssl3_send_alert(s, SSL3_AL_FATAL, al);
err:
return (0);
}
/*-
* Call this to get a new input record.
* It will return <= 0 if more data is needed, normally due to an error
* or non-blocking IO.
* When it finishes, one packet has been decoded and can be found in
* ssl->s3->rrec.type - is the type of record
* ssl->s3->rrec.data, - data
* ssl->s3->rrec.length, - number of bytes
*/
/* used only by dtls1_read_bytes */
int dtls1_get_record(SSL *s)
{
int ssl_major, ssl_minor;
int i, n;
SSL3_RECORD *rr;
unsigned char *p = NULL;
unsigned short version;
DTLS1_BITMAP *bitmap;
unsigned int is_next_epoch;
rr = &(s->s3->rrec);
again:
/*
* The epoch may have changed. If so, process all the pending records.
* This is a non-blocking operation.
*/
if (!dtls1_process_buffered_records(s))
return -1;
/* if we're renegotiating, then there may be buffered records */
if (dtls1_get_processed_record(s))
return 1;
/* get something from the wire */
/* check if we have the header */
if ((s->rstate != SSL_ST_READ_BODY) ||
(s->packet_length < DTLS1_RT_HEADER_LENGTH)) {
n = ssl3_read_n(s, DTLS1_RT_HEADER_LENGTH, s->s3->rbuf.len, 0);
/* read timeout is handled by dtls1_read_bytes */
if (n <= 0)
return (n); /* error or non-blocking */
/* this packet contained a partial record, dump it */
if (s->packet_length != DTLS1_RT_HEADER_LENGTH) {
s->packet_length = 0;
goto again;
}
s->rstate = SSL_ST_READ_BODY;
p = s->packet;
/* Pull apart the header into the DTLS1_RECORD */
rr->type = *(p++);
ssl_major = *(p++);
ssl_minor = *(p++);
version = (ssl_major << 8) | ssl_minor;
/* sequence number is 64 bits, with top 2 bytes = epoch */
n2s(p, rr->epoch);
memcpy(&(s->s3->read_sequence[2]), p, 6);
p += 6;
n2s(p, rr->length);
/* Lets check version */
if (!s->first_packet) {
if (version != s->version) {
/* unexpected version, silently discard */
rr->length = 0;
s->packet_length = 0;
goto again;
}
}
if ((version & 0xff00) != (s->version & 0xff00)) {
/* wrong version, silently discard record */
rr->length = 0;
s->packet_length = 0;
goto again;
}
if (rr->length > SSL3_RT_MAX_ENCRYPTED_LENGTH) {
/* record too long, silently discard it */
rr->length = 0;
s->packet_length = 0;
goto again;
}
/* now s->rstate == SSL_ST_READ_BODY */
}
/* s->rstate == SSL_ST_READ_BODY, get and decode the data */
if (rr->length > s->packet_length - DTLS1_RT_HEADER_LENGTH) {
/* now s->packet_length == DTLS1_RT_HEADER_LENGTH */
i = rr->length;
n = ssl3_read_n(s, i, i, 1);
/* this packet contained a partial record, dump it */
if (n != i) {
rr->length = 0;
s->packet_length = 0;
goto again;
}
/*
* now n == rr->length, and s->packet_length ==
* DTLS1_RT_HEADER_LENGTH + rr->length
*/
}
s->rstate = SSL_ST_READ_HEADER; /* set state for later operations */
/* match epochs. NULL means the packet is dropped on the floor */
bitmap = dtls1_get_bitmap(s, rr, &is_next_epoch);
if (bitmap == NULL) {
rr->length = 0;
s->packet_length = 0; /* dump this record */
goto again; /* get another record */
}
#ifndef OPENSSL_NO_SCTP
/* Only do replay check if no SCTP bio */
if (!BIO_dgram_is_sctp(SSL_get_rbio(s))) {
#endif
/*
* Check whether this is a repeat, or aged record. Don't check if
* we're listening and this message is a ClientHello. They can look
* as if they're replayed, since they arrive from different
* connections and would be dropped unnecessarily.
*/
if (!(s->d1->listen && rr->type == SSL3_RT_HANDSHAKE &&
s->packet_length > DTLS1_RT_HEADER_LENGTH &&
s->packet[DTLS1_RT_HEADER_LENGTH] == SSL3_MT_CLIENT_HELLO) &&
!dtls1_record_replay_check(s, bitmap)) {
rr->length = 0;
s->packet_length = 0; /* dump this record */
goto again; /* get another record */
}
#ifndef OPENSSL_NO_SCTP
}
#endif
/* just read a 0 length packet */
if (rr->length == 0)
goto again;
/*
* If this record is from the next epoch (either HM or ALERT), and a
* handshake is currently in progress, buffer it since it cannot be
* processed at this time. However, do not buffer anything while
* listening.
*/
if (is_next_epoch) {
if ((SSL_in_init(s) || s->in_handshake) && !s->d1->listen) {
if (dtls1_buffer_record
(s, &(s->d1->unprocessed_rcds), rr->seq_num) < 0)
return -1;
}
rr->length = 0;
s->packet_length = 0;
goto again;
}
if (!dtls1_process_record(s, bitmap)) {
rr->length = 0;
s->packet_length = 0; /* dump this record */
goto again; /* get another record */
}
return (1);
}
/*-
* Return up to 'len' payload bytes received in 'type' records.
* 'type' is one of the following:
*
* - SSL3_RT_HANDSHAKE (when ssl3_get_message calls us)
* - SSL3_RT_APPLICATION_DATA (when ssl3_read calls us)
* - 0 (during a shutdown, no data has to be returned)
*
* If we don't have stored data to work from, read a SSL/TLS record first
* (possibly multiple records if we still don't have anything to return).
*
* This function must handle any surprises the peer may have for us, such as
* Alert records (e.g. close_notify), ChangeCipherSpec records (not really
* a surprise, but handled as if it were), or renegotiation requests.
* Also if record payloads contain fragments too small to process, we store
* them until there is enough for the respective protocol (the record protocol
* may use arbitrary fragmentation and even interleaving):
* Change cipher spec protocol
* just 1 byte needed, no need for keeping anything stored
* Alert protocol
* 2 bytes needed (AlertLevel, AlertDescription)
* Handshake protocol
* 4 bytes needed (HandshakeType, uint24 length) -- we just have
* to detect unexpected Client Hello and Hello Request messages
* here, anything else is handled by higher layers
* Application data protocol
* none of our business
*/
int dtls1_read_bytes(SSL *s, int type, unsigned char *buf, int len, int peek)
{
int al, i, j, ret;
unsigned int n;
SSL3_RECORD *rr;
void (*cb) (const SSL *ssl, int type2, int val) = NULL;
if (s->s3->rbuf.buf == NULL) /* Not initialized yet */
if (!ssl3_setup_buffers(s))
return (-1);
/* XXX: check what the second '&& type' is about */
if ((type && (type != SSL3_RT_APPLICATION_DATA) &&
(type != SSL3_RT_HANDSHAKE) && type) ||
(peek && (type != SSL3_RT_APPLICATION_DATA))) {
SSLerr(SSL_F_DTLS1_READ_BYTES, ERR_R_INTERNAL_ERROR);
return -1;
}
/*
* check whether there's a handshake message (client hello?) waiting
*/
if ((ret = have_handshake_fragment(s, type, buf, len, peek)))
return ret;
/*
* Now s->d1->handshake_fragment_len == 0 if type == SSL3_RT_HANDSHAKE.
*/
#ifndef OPENSSL_NO_SCTP
/*
* Continue handshake if it had to be interrupted to read app data with
* SCTP.
*/
if ((!s->in_handshake && SSL_in_init(s)) ||
(BIO_dgram_is_sctp(SSL_get_rbio(s)) &&
(s->state == DTLS1_SCTP_ST_SR_READ_SOCK
|| s->state == DTLS1_SCTP_ST_CR_READ_SOCK)
&& s->s3->in_read_app_data != 2))
#else
if (!s->in_handshake && SSL_in_init(s))
#endif
{
/* type == SSL3_RT_APPLICATION_DATA */
i = s->handshake_func(s);
if (i < 0)
return (i);
if (i == 0) {
SSLerr(SSL_F_DTLS1_READ_BYTES, SSL_R_SSL_HANDSHAKE_FAILURE);
return (-1);
}
}
start:
s->rwstate = SSL_NOTHING;
/*-
* s->s3->rrec.type - is the type of record
* s->s3->rrec.data, - data
* s->s3->rrec.off, - offset into 'data' for next read
* s->s3->rrec.length, - number of bytes.
*/
rr = &(s->s3->rrec);
/*
* We are not handshaking and have no data yet, so process data buffered
* during the last handshake in advance, if any.
*/
if (s->state == SSL_ST_OK && rr->length == 0) {
pitem *item;
item = pqueue_pop(s->d1->buffered_app_data.q);
if (item) {
#ifndef OPENSSL_NO_SCTP
/* Restore bio_dgram_sctp_rcvinfo struct */
if (BIO_dgram_is_sctp(SSL_get_rbio(s))) {
DTLS1_RECORD_DATA *rdata = (DTLS1_RECORD_DATA *)item->data;
BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SCTP_SET_RCVINFO,
sizeof(rdata->recordinfo), &rdata->recordinfo);
}
#endif
dtls1_copy_record(s, item);
OPENSSL_free(item->data);
pitem_free(item);
}
}
/* Check for timeout */
if (dtls1_handle_timeout(s) > 0)
goto start;
/* get new packet if necessary */
if ((rr->length == 0) || (s->rstate == SSL_ST_READ_BODY)) {
ret = dtls1_get_record(s);
if (ret <= 0) {
ret = dtls1_read_failed(s, ret);
/* anything other than a timeout is an error */
if (ret <= 0)
return (ret);
else
goto start;
}
}
if (s->d1->listen && rr->type != SSL3_RT_HANDSHAKE) {
rr->length = 0;
goto start;
}
/* we now have a packet which can be read and processed */
if (s->s3->change_cipher_spec /* set when we receive ChangeCipherSpec,
* reset by ssl3_get_finished */
&& (rr->type != SSL3_RT_HANDSHAKE)) {
/*
* We now have application data between CCS and Finished. Most likely
* the packets were reordered on their way, so buffer the application
* data for later processing rather than dropping the connection.
*/
if (dtls1_buffer_record(s, &(s->d1->buffered_app_data), rr->seq_num) <
0) {
SSLerr(SSL_F_DTLS1_READ_BYTES, ERR_R_INTERNAL_ERROR);
return -1;
}
rr->length = 0;
goto start;
}
/*
* If the other end has shut down, throw anything we read away (even in
* 'peek' mode)
*/
if (s->shutdown & SSL_RECEIVED_SHUTDOWN) {
rr->length = 0;
s->rwstate = SSL_NOTHING;
return (0);
}
if (type == rr->type) { /* SSL3_RT_APPLICATION_DATA or
* SSL3_RT_HANDSHAKE */
/*
* make sure that we are not getting application data when we are
* doing a handshake for the first time
*/
if (SSL_in_init(s) && (type == SSL3_RT_APPLICATION_DATA) &&
(s->enc_read_ctx == NULL)) {
al = SSL_AD_UNEXPECTED_MESSAGE;
SSLerr(SSL_F_DTLS1_READ_BYTES, SSL_R_APP_DATA_IN_HANDSHAKE);
goto f_err;
}
if (len <= 0)
return (len);
if ((unsigned int)len > rr->length)
n = rr->length;
else
n = (unsigned int)len;
memcpy(buf, &(rr->data[rr->off]), n);
if (!peek) {
rr->length -= n;
rr->off += n;
if (rr->length == 0) {
s->rstate = SSL_ST_READ_HEADER;
rr->off = 0;
}
}
#ifndef OPENSSL_NO_SCTP
/*
* We were about to renegotiate but had to read belated application
* data first, so retry.
*/
if (BIO_dgram_is_sctp(SSL_get_rbio(s)) &&
rr->type == SSL3_RT_APPLICATION_DATA &&
(s->state == DTLS1_SCTP_ST_SR_READ_SOCK
|| s->state == DTLS1_SCTP_ST_CR_READ_SOCK)) {
s->rwstate = SSL_READING;
BIO_clear_retry_flags(SSL_get_rbio(s));
BIO_set_retry_read(SSL_get_rbio(s));
}
/*
* We might had to delay a close_notify alert because of reordered
* app data. If there was an alert and there is no message to read
* anymore, finally set shutdown.
*/
if (BIO_dgram_is_sctp(SSL_get_rbio(s)) &&
s->d1->shutdown_received
&& !BIO_dgram_sctp_msg_waiting(SSL_get_rbio(s))) {
s->shutdown |= SSL_RECEIVED_SHUTDOWN;
return (0);
}
#endif
return (n);
}
/*
* If we get here, then type != rr->type; if we have a handshake message,
* then it was unexpected (Hello Request or Client Hello).
*/
/*
* In case of record types for which we have 'fragment' storage, fill
* that so that we can process the data at a fixed place.
*/
{
unsigned int k, dest_maxlen = 0;
unsigned char *dest = NULL;
unsigned int *dest_len = NULL;
if (rr->type == SSL3_RT_HANDSHAKE) {
dest_maxlen = sizeof s->d1->handshake_fragment;
dest = s->d1->handshake_fragment;
dest_len = &s->d1->handshake_fragment_len;
} else if (rr->type == SSL3_RT_ALERT) {
dest_maxlen = sizeof(s->d1->alert_fragment);
dest = s->d1->alert_fragment;
dest_len = &s->d1->alert_fragment_len;
}
#ifndef OPENSSL_NO_HEARTBEATS
else if (rr->type == TLS1_RT_HEARTBEAT) {
dtls1_process_heartbeat(s);
/* Exit and notify application to read again */
rr->length = 0;
s->rwstate = SSL_READING;
BIO_clear_retry_flags(SSL_get_rbio(s));
BIO_set_retry_read(SSL_get_rbio(s));
return (-1);
}
#endif
/* else it's a CCS message, or application data or wrong */
else if (rr->type != SSL3_RT_CHANGE_CIPHER_SPEC) {
/*
* Application data while renegotiating is allowed. Try again
* reading.
*/
if (rr->type == SSL3_RT_APPLICATION_DATA) {
BIO *bio;
s->s3->in_read_app_data = 2;
bio = SSL_get_rbio(s);
s->rwstate = SSL_READING;
BIO_clear_retry_flags(bio);
BIO_set_retry_read(bio);
return (-1);
}
/* Not certain if this is the right error handling */
al = SSL_AD_UNEXPECTED_MESSAGE;
SSLerr(SSL_F_DTLS1_READ_BYTES, SSL_R_UNEXPECTED_RECORD);
goto f_err;
}
if (dest_maxlen > 0) {
/*
* XDTLS: In a pathalogical case, the Client Hello may be
* fragmented--don't always expect dest_maxlen bytes
*/
if (rr->length < dest_maxlen) {
#ifdef DTLS1_AD_MISSING_HANDSHAKE_MESSAGE
/*
* for normal alerts rr->length is 2, while
* dest_maxlen is 7 if we were to handle this
* non-existing alert...
*/
FIX ME
#endif
s->rstate = SSL_ST_READ_HEADER;
rr->length = 0;
goto start;
}
/* now move 'n' bytes: */
for (k = 0; k < dest_maxlen; k++) {
dest[k] = rr->data[rr->off++];
rr->length--;
}
*dest_len = dest_maxlen;
}
}
/*-
* s->d1->handshake_fragment_len == 12 iff rr->type == SSL3_RT_HANDSHAKE;
* s->d1->alert_fragment_len == 7 iff rr->type == SSL3_RT_ALERT.
* (Possibly rr is 'empty' now, i.e. rr->length may be 0.)
*/
/* If we are a client, check for an incoming 'Hello Request': */
if ((!s->server) &&
(s->d1->handshake_fragment_len >= DTLS1_HM_HEADER_LENGTH) &&
(s->d1->handshake_fragment[0] == SSL3_MT_HELLO_REQUEST) &&
(s->session != NULL) && (s->session->cipher != NULL)) {
s->d1->handshake_fragment_len = 0;
if ((s->d1->handshake_fragment[1] != 0) ||
(s->d1->handshake_fragment[2] != 0) ||
(s->d1->handshake_fragment[3] != 0)) {
al = SSL_AD_DECODE_ERROR;
SSLerr(SSL_F_DTLS1_READ_BYTES, SSL_R_BAD_HELLO_REQUEST);
goto f_err;
}
/*
* no need to check sequence number on HELLO REQUEST messages
*/
if (s->msg_callback)
s->msg_callback(0, s->version, SSL3_RT_HANDSHAKE,
s->d1->handshake_fragment, 4, s,
s->msg_callback_arg);
if (SSL_is_init_finished(s) &&
!(s->s3->flags & SSL3_FLAGS_NO_RENEGOTIATE_CIPHERS) &&
!s->s3->renegotiate) {
s->d1->handshake_read_seq++;
s->new_session = 1;
ssl3_renegotiate(s);
if (ssl3_renegotiate_check(s)) {
i = s->handshake_func(s);
if (i < 0)
return (i);
if (i == 0) {
SSLerr(SSL_F_DTLS1_READ_BYTES,
SSL_R_SSL_HANDSHAKE_FAILURE);
return (-1);
}
if (!(s->mode & SSL_MODE_AUTO_RETRY)) {
if (s->s3->rbuf.left == 0) { /* no read-ahead left? */
BIO *bio;
/*
* In the case where we try to read application data,
* but we trigger an SSL handshake, we return -1 with
* the retry option set. Otherwise renegotiation may
* cause nasty problems in the blocking world
*/
s->rwstate = SSL_READING;
bio = SSL_get_rbio(s);
BIO_clear_retry_flags(bio);
BIO_set_retry_read(bio);
return (-1);
}
}
}
}
/*
* we either finished a handshake or ignored the request, now try
* again to obtain the (application) data we were asked for
*/
goto start;
}
if (s->d1->alert_fragment_len >= DTLS1_AL_HEADER_LENGTH) {
int alert_level = s->d1->alert_fragment[0];
int alert_descr = s->d1->alert_fragment[1];
s->d1->alert_fragment_len = 0;
if (s->msg_callback)
s->msg_callback(0, s->version, SSL3_RT_ALERT,
s->d1->alert_fragment, 2, s, s->msg_callback_arg);
if (s->info_callback != NULL)
cb = s->info_callback;
else if (s->ctx->info_callback != NULL)
cb = s->ctx->info_callback;
if (cb != NULL) {
j = (alert_level << 8) | alert_descr;
cb(s, SSL_CB_READ_ALERT, j);
}
if (alert_level == SSL3_AL_WARNING) {
s->s3->warn_alert = alert_descr;
if (alert_descr == SSL_AD_CLOSE_NOTIFY) {
#ifndef OPENSSL_NO_SCTP
/*
* With SCTP and streams the socket may deliver app data
* after a close_notify alert. We have to check this first so
* that nothing gets discarded.
*/
if (BIO_dgram_is_sctp(SSL_get_rbio(s)) &&
BIO_dgram_sctp_msg_waiting(SSL_get_rbio(s))) {
s->d1->shutdown_received = 1;
s->rwstate = SSL_READING;
BIO_clear_retry_flags(SSL_get_rbio(s));
BIO_set_retry_read(SSL_get_rbio(s));
return -1;
}
#endif
s->shutdown |= SSL_RECEIVED_SHUTDOWN;
return (0);
}
#if 0
/* XXX: this is a possible improvement in the future */
/* now check if it's a missing record */
if (alert_descr == DTLS1_AD_MISSING_HANDSHAKE_MESSAGE) {
unsigned short seq;
unsigned int frag_off;
unsigned char *p = &(s->d1->alert_fragment[2]);
n2s(p, seq);
n2l3(p, frag_off);
dtls1_retransmit_message(s,
dtls1_get_queue_priority
(frag->msg_header.seq, 0), frag_off,
&found);
if (!found && SSL_in_init(s)) {
/*
* fprintf( stderr,"in init = %d\n", SSL_in_init(s));
*/
/*
* requested a message not yet sent, send an alert
* ourselves
*/
ssl3_send_alert(s, SSL3_AL_WARNING,
DTLS1_AD_MISSING_HANDSHAKE_MESSAGE);
}
}
#endif
} else if (alert_level == SSL3_AL_FATAL) {
char tmp[16];
s->rwstate = SSL_NOTHING;
s->s3->fatal_alert = alert_descr;
SSLerr(SSL_F_DTLS1_READ_BYTES,
SSL_AD_REASON_OFFSET + alert_descr);
BIO_snprintf(tmp, sizeof tmp, "%d", alert_descr);
ERR_add_error_data(2, "SSL alert number ", tmp);
s->shutdown |= SSL_RECEIVED_SHUTDOWN;
SSL_CTX_remove_session(s->ctx, s->session);
return (0);
} else {
al = SSL_AD_ILLEGAL_PARAMETER;
SSLerr(SSL_F_DTLS1_READ_BYTES, SSL_R_UNKNOWN_ALERT_TYPE);
goto f_err;
}
goto start;
}
if (s->shutdown & SSL_SENT_SHUTDOWN) { /* but we have not received a
* shutdown */
s->rwstate = SSL_NOTHING;
rr->length = 0;
return (0);
}
if (rr->type == SSL3_RT_CHANGE_CIPHER_SPEC) {
struct ccs_header_st ccs_hdr;
unsigned int ccs_hdr_len = DTLS1_CCS_HEADER_LENGTH;
dtls1_get_ccs_header(rr->data, &ccs_hdr);
if (s->version == DTLS1_BAD_VER)
ccs_hdr_len = 3;
/*
* 'Change Cipher Spec' is just a single byte, so we know exactly
* what the record payload has to look like
*/
/* XDTLS: check that epoch is consistent */
if ((rr->length != ccs_hdr_len) ||
(rr->off != 0) || (rr->data[0] != SSL3_MT_CCS)) {
i = SSL_AD_ILLEGAL_PARAMETER;
SSLerr(SSL_F_DTLS1_READ_BYTES, SSL_R_BAD_CHANGE_CIPHER_SPEC);
goto err;
}
rr->length = 0;
if (s->msg_callback)
s->msg_callback(0, s->version, SSL3_RT_CHANGE_CIPHER_SPEC,
rr->data, 1, s, s->msg_callback_arg);
/*
* We can't process a CCS now, because previous handshake messages
* are still missing, so just drop it.
*/
if (!s->d1->change_cipher_spec_ok) {
goto start;
}
s->d1->change_cipher_spec_ok = 0;
s->s3->change_cipher_spec = 1;
if (!ssl3_do_change_cipher_spec(s))
goto err;
/* do this whenever CCS is processed */
dtls1_reset_seq_numbers(s, SSL3_CC_READ);
if (s->version == DTLS1_BAD_VER)
s->d1->handshake_read_seq++;
#ifndef OPENSSL_NO_SCTP
/*
* Remember that a CCS has been received, so that an old key of
* SCTP-Auth can be deleted when a CCS is sent. Will be ignored if no
* SCTP is used
*/
BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_AUTH_CCS_RCVD, 1, NULL);
#endif
goto start;
}
/*
* Unexpected handshake message (Client Hello, or protocol violation)
*/
if ((s->d1->handshake_fragment_len >= DTLS1_HM_HEADER_LENGTH) &&
!s->in_handshake) {
struct hm_header_st msg_hdr;
/* this may just be a stale retransmit */
dtls1_get_message_header(rr->data, &msg_hdr);
if (rr->epoch != s->d1->r_epoch) {
rr->length = 0;
goto start;
}
/*
* If we are server, we may have a repeated FINISHED of the client
* here, then retransmit our CCS and FINISHED.
*/
if (msg_hdr.type == SSL3_MT_FINISHED) {
if (dtls1_check_timeout_num(s) < 0)
return -1;
dtls1_retransmit_buffered_messages(s);
rr->length = 0;
goto start;
}
if (((s->state & SSL_ST_MASK) == SSL_ST_OK) &&
!(s->s3->flags & SSL3_FLAGS_NO_RENEGOTIATE_CIPHERS)) {
#if 0 /* worked only because C operator preferences
* are not as expected (and because this is
* not really needed for clients except for
* detecting protocol violations): */
s->state = SSL_ST_BEFORE | (s->server)
? SSL_ST_ACCEPT : SSL_ST_CONNECT;
#else
s->state = s->server ? SSL_ST_ACCEPT : SSL_ST_CONNECT;
#endif
s->renegotiate = 1;
s->new_session = 1;
}
i = s->handshake_func(s);
if (i < 0)
return (i);
if (i == 0) {
SSLerr(SSL_F_DTLS1_READ_BYTES, SSL_R_SSL_HANDSHAKE_FAILURE);
return (-1);
}
if (!(s->mode & SSL_MODE_AUTO_RETRY)) {
if (s->s3->rbuf.left == 0) { /* no read-ahead left? */
BIO *bio;
/*
* In the case where we try to read application data, but we
* trigger an SSL handshake, we return -1 with the retry
* option set. Otherwise renegotiation may cause nasty
* problems in the blocking world
*/
s->rwstate = SSL_READING;
bio = SSL_get_rbio(s);
BIO_clear_retry_flags(bio);
BIO_set_retry_read(bio);
return (-1);
}
}
goto start;
}
switch (rr->type) {
default:
#ifndef OPENSSL_NO_TLS
/* TLS just ignores unknown message types */
if (s->version == TLS1_VERSION) {
rr->length = 0;
goto start;
}
#endif
al = SSL_AD_UNEXPECTED_MESSAGE;
SSLerr(SSL_F_DTLS1_READ_BYTES, SSL_R_UNEXPECTED_RECORD);
goto f_err;
case SSL3_RT_CHANGE_CIPHER_SPEC:
case SSL3_RT_ALERT:
case SSL3_RT_HANDSHAKE:
/*
* we already handled all of these, with the possible exception of
* SSL3_RT_HANDSHAKE when s->in_handshake is set, but that should not
* happen when type != rr->type
*/
al = SSL_AD_UNEXPECTED_MESSAGE;
SSLerr(SSL_F_DTLS1_READ_BYTES, ERR_R_INTERNAL_ERROR);
goto f_err;
case SSL3_RT_APPLICATION_DATA:
/*
* At this point, we were expecting handshake data, but have
* application data. If the library was running inside ssl3_read()
* (i.e. in_read_app_data is set) and it makes sense to read
* application data at this point (session renegotiation not yet
* started), we will indulge it.
*/
if (s->s3->in_read_app_data &&
(s->s3->total_renegotiations != 0) &&
(((s->state & SSL_ST_CONNECT) &&
(s->state >= SSL3_ST_CW_CLNT_HELLO_A) &&
(s->state <= SSL3_ST_CR_SRVR_HELLO_A)
) || ((s->state & SSL_ST_ACCEPT) &&
(s->state <= SSL3_ST_SW_HELLO_REQ_A) &&
(s->state >= SSL3_ST_SR_CLNT_HELLO_A)
)
)) {
s->s3->in_read_app_data = 2;
return (-1);
} else {
al = SSL_AD_UNEXPECTED_MESSAGE;
SSLerr(SSL_F_DTLS1_READ_BYTES, SSL_R_UNEXPECTED_RECORD);
goto f_err;
}
}
/* not reached */
f_err:
ssl3_send_alert(s, SSL3_AL_FATAL, al);
err:
return (-1);
}
int dtls1_write_app_data_bytes(SSL *s, int type, const void *buf_, int len)
{
int i;
#ifndef OPENSSL_NO_SCTP
/*
* Check if we have to continue an interrupted handshake for reading
* belated app data with SCTP.
*/
if ((SSL_in_init(s) && !s->in_handshake) ||
(BIO_dgram_is_sctp(SSL_get_wbio(s)) &&
(s->state == DTLS1_SCTP_ST_SR_READ_SOCK
|| s->state == DTLS1_SCTP_ST_CR_READ_SOCK)))
#else
if (SSL_in_init(s) && !s->in_handshake)
#endif
{
i = s->handshake_func(s);
if (i < 0)
return (i);
if (i == 0) {
SSLerr(SSL_F_DTLS1_WRITE_APP_DATA_BYTES,
SSL_R_SSL_HANDSHAKE_FAILURE);
return -1;
}
}
if (len > SSL3_RT_MAX_PLAIN_LENGTH) {
SSLerr(SSL_F_DTLS1_WRITE_APP_DATA_BYTES, SSL_R_DTLS_MESSAGE_TOO_BIG);
return -1;
}
i = dtls1_write_bytes(s, type, buf_, len);
return i;
}
/*
* this only happens when a client hello is received and a handshake
* is started.
*/
static int
have_handshake_fragment(SSL *s, int type, unsigned char *buf,
int len, int peek)
{
if ((type == SSL3_RT_HANDSHAKE) && (s->d1->handshake_fragment_len > 0))
/* (partially) satisfy request from storage */
{
unsigned char *src = s->d1->handshake_fragment;
unsigned char *dst = buf;
unsigned int k, n;
/* peek == 0 */
n = 0;
while ((len > 0) && (s->d1->handshake_fragment_len > 0)) {
*dst++ = *src++;
len--;
s->d1->handshake_fragment_len--;
n++;
}
/* move any remaining fragment bytes: */
for (k = 0; k < s->d1->handshake_fragment_len; k++)
s->d1->handshake_fragment[k] = *src++;
return n;
}
return 0;
}
/*
* Call this to write data in records of type 'type' It will return <= 0 if
* not all data has been sent or non-blocking IO.
*/
int dtls1_write_bytes(SSL *s, int type, const void *buf, int len)
{
int i;
OPENSSL_assert(len <= SSL3_RT_MAX_PLAIN_LENGTH);
s->rwstate = SSL_NOTHING;
i = do_dtls1_write(s, type, buf, len, 0);
return i;
}
int do_dtls1_write(SSL *s, int type, const unsigned char *buf,
unsigned int len, int create_empty_fragment)
{
unsigned char *p, *pseq;
int i, mac_size, clear = 0;
int prefix_len = 0;
SSL3_RECORD *wr;
SSL3_BUFFER *wb;
SSL_SESSION *sess;
int bs;
/*
* first check if there is a SSL3_BUFFER still being written out. This
* will happen with non blocking IO
*/
if (s->s3->wbuf.left != 0) {
OPENSSL_assert(0); /* XDTLS: want to see if we ever get here */
return (ssl3_write_pending(s, type, buf, len));
}
/* If we have an alert to send, lets send it */
if (s->s3->alert_dispatch) {
i = s->method->ssl_dispatch_alert(s);
if (i <= 0)
return (i);
/* if it went, fall through and send more stuff */
}
if (len == 0 && !create_empty_fragment)
return 0;
wr = &(s->s3->wrec);
wb = &(s->s3->wbuf);
sess = s->session;
if ((sess == NULL) ||
(s->enc_write_ctx == NULL) || (EVP_MD_CTX_md(s->write_hash) == NULL))
clear = 1;
if (clear)
mac_size = 0;
else {
mac_size = EVP_MD_CTX_size(s->write_hash);
if (mac_size < 0)
goto err;
}
/* DTLS implements explicit IV, so no need for empty fragments */
#if 0
/*
* 'create_empty_fragment' is true only when this function calls itself
*/
if (!clear && !create_empty_fragment && !s->s3->empty_fragment_done
&& SSL_version(s) != DTLS1_VERSION && SSL_version(s) != DTLS1_BAD_VER)
{
/*
* countermeasure against known-IV weakness in CBC ciphersuites (see
* http://www.openssl.org/~bodo/tls-cbc.txt)
*/
if (s->s3->need_empty_fragments && type == SSL3_RT_APPLICATION_DATA) {
/*
* recursive function call with 'create_empty_fragment' set; this
* prepares and buffers the data for an empty fragment (these
* 'prefix_len' bytes are sent out later together with the actual
* payload)
*/
prefix_len = s->method->do_ssl_write(s, type, buf, 0, 1);
if (prefix_len <= 0)
goto err;
if (s->s3->wbuf.len <
(size_t)prefix_len + SSL3_RT_MAX_PACKET_SIZE) {
/* insufficient space */
SSLerr(SSL_F_DO_DTLS1_WRITE, ERR_R_INTERNAL_ERROR);
goto err;
}
}
s->s3->empty_fragment_done = 1;
}
#endif
p = wb->buf + prefix_len;
/* write the header */
*(p++) = type & 0xff;
wr->type = type;
*(p++) = (s->version >> 8);
*(p++) = s->version & 0xff;
/* field where we are to write out packet epoch, seq num and len */
pseq = p;
p += 10;
/* lets setup the record stuff. */
/*
* Make space for the explicit IV in case of CBC. (this is a bit of a
* boundary violation, but what the heck).
*/
if (s->enc_write_ctx &&
(EVP_CIPHER_mode(s->enc_write_ctx->cipher) & EVP_CIPH_CBC_MODE))
bs = EVP_CIPHER_block_size(s->enc_write_ctx->cipher);
else
bs = 0;
wr->data = p + bs; /* make room for IV in case of CBC */
wr->length = (int)len;
wr->input = (unsigned char *)buf;
/*
* we now 'read' from wr->input, wr->length bytes into wr->data
*/
/* first we compress */
if (s->compress != NULL) {
if (!ssl3_do_compress(s)) {
SSLerr(SSL_F_DO_DTLS1_WRITE, SSL_R_COMPRESSION_FAILURE);
goto err;
}
} else {
memcpy(wr->data, wr->input, wr->length);
wr->input = wr->data;
}
/*
* we should still have the output to wr->data and the input from
* wr->input. Length should be wr->length. wr->data still points in the
* wb->buf
*/
if (mac_size != 0) {
if (s->method->ssl3_enc->mac(s, &(p[wr->length + bs]), 1) < 0)
goto err;
wr->length += mac_size;
}
/* this is true regardless of mac size */
wr->input = p;
wr->data = p;
/* ssl3_enc can only have an error on read */
if (bs) { /* bs != 0 in case of CBC */
if (RAND_bytes(p, bs) <= 0)
goto err;
/*
* master IV and last CBC residue stand for the rest of randomness
*/
wr->length += bs;
}
if (s->method->ssl3_enc->enc(s, 1) < 1)
goto err;
/* record length after mac and block padding */
/*
* if (type == SSL3_RT_APPLICATION_DATA || (type == SSL3_RT_ALERT && !
* SSL_in_init(s)))
*/
/* there's only one epoch between handshake and app data */
s2n(s->d1->w_epoch, pseq);
/* XDTLS: ?? */
/*
* else s2n(s->d1->handshake_epoch, pseq);
*/
memcpy(pseq, &(s->s3->write_sequence[2]), 6);
pseq += 6;
s2n(wr->length, pseq);
/*
* we should now have wr->data pointing to the encrypted data, which is
* wr->length long
*/
wr->type = type; /* not needed but helps for debugging */
wr->length += DTLS1_RT_HEADER_LENGTH;
#if 0 /* this is now done at the message layer */
/* buffer the record, making it easy to handle retransmits */
if (type == SSL3_RT_HANDSHAKE || type == SSL3_RT_CHANGE_CIPHER_SPEC)
dtls1_buffer_record(s, wr->data, wr->length,
*((PQ_64BIT *) & (s->s3->write_sequence[0])));
#endif
ssl3_record_sequence_update(&(s->s3->write_sequence[0]));
if (create_empty_fragment) {
/*
* we are in a recursive call; just return the length, don't write
* out anything here
*/
return wr->length;
}
/* now let's set up wb */
wb->left = prefix_len + wr->length;
wb->offset = 0;
/*
* memorize arguments so that ssl3_write_pending can detect bad write
* retries later
*/
s->s3->wpend_tot = len;
s->s3->wpend_buf = buf;
s->s3->wpend_type = type;
s->s3->wpend_ret = len;
/* we now just need to write the buffer */
return ssl3_write_pending(s, type, buf, len);
err:
return -1;
}
static int dtls1_record_replay_check(SSL *s, DTLS1_BITMAP *bitmap)
{
int cmp;
unsigned int shift;
const unsigned char *seq = s->s3->read_sequence;
cmp = satsub64be(seq, bitmap->max_seq_num);
if (cmp > 0) {
memcpy(s->s3->rrec.seq_num, seq, 8);
return 1; /* this record in new */
}
shift = -cmp;
if (shift >= sizeof(bitmap->map) * 8)
return 0; /* stale, outside the window */
else if (bitmap->map & (1UL << shift))
return 0; /* record previously received */
memcpy(s->s3->rrec.seq_num, seq, 8);
return 1;
}
static void dtls1_record_bitmap_update(SSL *s, DTLS1_BITMAP *bitmap)
{
int cmp;
unsigned int shift;
const unsigned char *seq = s->s3->read_sequence;
cmp = satsub64be(seq, bitmap->max_seq_num);
if (cmp > 0) {
shift = cmp;
if (shift < sizeof(bitmap->map) * 8)
bitmap->map <<= shift, bitmap->map |= 1UL;
else
bitmap->map = 1UL;
memcpy(bitmap->max_seq_num, seq, 8);
} else {
shift = -cmp;
if (shift < sizeof(bitmap->map) * 8)
bitmap->map |= 1UL << shift;
}
}
int dtls1_dispatch_alert(SSL *s)
{
int i, j;
void (*cb) (const SSL *ssl, int type, int val) = NULL;
unsigned char buf[DTLS1_AL_HEADER_LENGTH];
unsigned char *ptr = &buf[0];
s->s3->alert_dispatch = 0;
memset(buf, 0x00, sizeof(buf));
*ptr++ = s->s3->send_alert[0];
*ptr++ = s->s3->send_alert[1];
#ifdef DTLS1_AD_MISSING_HANDSHAKE_MESSAGE
if (s->s3->send_alert[1] == DTLS1_AD_MISSING_HANDSHAKE_MESSAGE) {
s2n(s->d1->handshake_read_seq, ptr);
# if 0
if (s->d1->r_msg_hdr.frag_off == 0)
/*
* waiting for a new msg
*/
else
s2n(s->d1->r_msg_hdr.seq, ptr); /* partial msg read */
# endif
# if 0
fprintf(stderr,
"s->d1->handshake_read_seq = %d, s->d1->r_msg_hdr.seq = %d\n",
s->d1->handshake_read_seq, s->d1->r_msg_hdr.seq);
# endif
l2n3(s->d1->r_msg_hdr.frag_off, ptr);
}
#endif
i = do_dtls1_write(s, SSL3_RT_ALERT, &buf[0], sizeof(buf), 0);
if (i <= 0) {
s->s3->alert_dispatch = 1;
/* fprintf( stderr, "not done with alert\n" ); */
} else {
if (s->s3->send_alert[0] == SSL3_AL_FATAL
#ifdef DTLS1_AD_MISSING_HANDSHAKE_MESSAGE
|| s->s3->send_alert[1] == DTLS1_AD_MISSING_HANDSHAKE_MESSAGE
#endif
)
(void)BIO_flush(s->wbio);
if (s->msg_callback)
s->msg_callback(1, s->version, SSL3_RT_ALERT, s->s3->send_alert,
2, s, s->msg_callback_arg);
if (s->info_callback != NULL)
cb = s->info_callback;
else if (s->ctx->info_callback != NULL)
cb = s->ctx->info_callback;
if (cb != NULL) {
j = (s->s3->send_alert[0] << 8) | s->s3->send_alert[1];
cb(s, SSL_CB_WRITE_ALERT, j);
}
}
return (i);
}
static DTLS1_BITMAP *dtls1_get_bitmap(SSL *s, SSL3_RECORD *rr,
unsigned int *is_next_epoch)
{
*is_next_epoch = 0;
/* In current epoch, accept HM, CCS, DATA, & ALERT */
if (rr->epoch == s->d1->r_epoch)
return &s->d1->bitmap;
/*
* Only HM and ALERT messages can be from the next epoch and only if we
* have already processed all of the unprocessed records from the last
* epoch
*/
else if (rr->epoch == (unsigned long)(s->d1->r_epoch + 1) &&
s->d1->unprocessed_rcds.epoch != s->d1->r_epoch &&
(rr->type == SSL3_RT_HANDSHAKE || rr->type == SSL3_RT_ALERT)) {
*is_next_epoch = 1;
return &s->d1->next_bitmap;
}
return NULL;
}
#if 0
static int
dtls1_record_needs_buffering(SSL *s, SSL3_RECORD *rr,
unsigned short *priority, unsigned long *offset)
{
/* alerts are passed up immediately */
if (rr->type == SSL3_RT_APPLICATION_DATA || rr->type == SSL3_RT_ALERT)
return 0;
/*
* Only need to buffer if a handshake is underway. (this implies that
* Hello Request and Client Hello are passed up immediately)
*/
if (SSL_in_init(s)) {
unsigned char *data = rr->data;
/* need to extract the HM/CCS sequence number here */
if (rr->type == SSL3_RT_HANDSHAKE ||
rr->type == SSL3_RT_CHANGE_CIPHER_SPEC) {
unsigned short seq_num;
struct hm_header_st msg_hdr;
struct ccs_header_st ccs_hdr;
if (rr->type == SSL3_RT_HANDSHAKE) {
dtls1_get_message_header(data, &msg_hdr);
seq_num = msg_hdr.seq;
*offset = msg_hdr.frag_off;
} else {
dtls1_get_ccs_header(data, &ccs_hdr);
seq_num = ccs_hdr.seq;
*offset = 0;
}
/*
* this is either a record we're waiting for, or a retransmit of
* something we happened to previously receive (higher layers
* will drop the repeat silently
*/
if (seq_num < s->d1->handshake_read_seq)
return 0;
if (rr->type == SSL3_RT_HANDSHAKE &&
seq_num == s->d1->handshake_read_seq &&
msg_hdr.frag_off < s->d1->r_msg_hdr.frag_off)
return 0;
else if (seq_num == s->d1->handshake_read_seq &&
(rr->type == SSL3_RT_CHANGE_CIPHER_SPEC ||
msg_hdr.frag_off == s->d1->r_msg_hdr.frag_off))
return 0;
else {
*priority = seq_num;
return 1;
}
} else /* unknown record type */
return 0;
}
return 0;
}
#endif
void dtls1_reset_seq_numbers(SSL *s, int rw)
{
unsigned char *seq;
unsigned int seq_bytes = sizeof(s->s3->read_sequence);
if (rw & SSL3_CC_READ) {
seq = s->s3->read_sequence;
s->d1->r_epoch++;
memcpy(&(s->d1->bitmap), &(s->d1->next_bitmap), sizeof(DTLS1_BITMAP));
memset(&(s->d1->next_bitmap), 0x00, sizeof(DTLS1_BITMAP));
/*
* We must not use any buffered messages received from the previous
* epoch
*/
dtls1_clear_received_buffer(s);
} else {
seq = s->s3->write_sequence;
memcpy(s->d1->last_write_sequence, seq,
sizeof(s->s3->write_sequence));
s->d1->w_epoch++;
}
memset(seq, 0x00, seq_bytes);
}
Reference in a new issue View git blame Copy permalink