Commit message: Fix crash in dtls1_get_record whilst in the listen state where you get two
separate reads performed - one for the header and one for the body of the
handshake record.

CVE-2014-3571

Reviewed-by: Matt Caswell <matt@openssl.org>
CVE: CVE-2014-3571
CWE: NVD-CWE-Other
Vulnerability description: OpenSSL before 0.9.8zd, 1.0.0 before 1.0.0p, and 1.0.1 before 1.0.1k allows remote attackers to cause a denial of service (NULL pointer dereference and application crash) via a crafted DTLS message that is processed with a different read operation for the handshake header than for the handshake body, related to the dtls1_get_record function in d1_pkt.c and the ssl3_read_n function in s3_pkt.c.

Project: openssl

int ssl3_do_change_cipher_spec(SSL *s)
	{
	int i;
	const char *sender;
	int slen;

	if (s->state & SSL_ST_ACCEPT)
		i=SSL3_CHANGE_CIPHER_SERVER_READ;
	else
		i=SSL3_CHANGE_CIPHER_CLIENT_READ;

	if (s->s3->tmp.key_block == NULL)
		{
		if (s->session == NULL || s->session->master_key_length == 0)
			{
			/* might happen if dtls1_read_bytes() calls this */
			SSLerr(SSL_F_SSL3_DO_CHANGE_CIPHER_SPEC,SSL_R_CCS_RECEIVED_EARLY);
			return (0);
			}

		s->session->cipher=s->s3->tmp.new_cipher;
		if (!s->method->ssl3_enc->setup_key_block(s)) return(0);
		}

	if (!s->method->ssl3_enc->change_cipher_state(s,i))
		return(0);

	/* we have to record the message digest at
	 * this point so we can get it before we read
	 * the finished message */
	if (s->state & SSL_ST_CONNECT)
		{
		sender=s->method->ssl3_enc->server_finished_label;
		slen=s->method->ssl3_enc->server_finished_label_len;
		}
	else
		{
		sender=s->method->ssl3_enc->client_finished_label;
		slen=s->method->ssl3_enc->client_finished_label_len;
		}

	i = s->method->ssl3_enc->final_finish_mac(s,
		sender,slen,s->s3->tmp.peer_finish_md);
	if (i == 0)
		{
		SSLerr(SSL_F_SSL3_DO_CHANGE_CIPHER_SPEC, ERR_R_INTERNAL_ERROR);
		return 0;
		}
	s->s3->tmp.peer_finish_md_len = i;

	return(1);
	}

Project: openssl

static int ssl3_get_record(SSL *s)
	{
	int ssl_major,ssl_minor,al;
	int enc_err,n,i,ret= -1;
	SSL3_RECORD *rr;
	SSL_SESSION *sess;
	unsigned char *p;
	unsigned char md[EVP_MAX_MD_SIZE];
	short version;
	unsigned mac_size;
	size_t extra;
	unsigned empty_record_count = 0;

	rr= &(s->s3->rrec);
	sess=s->session;

	if (s->options & SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER)
		extra=SSL3_RT_MAX_EXTRA;
	else
		extra=0;
	if (extra && !s->s3->init_extra)
		{
		/* An application error: SLS_OP_MICROSOFT_BIG_SSLV3_BUFFER
		 * set after ssl3_setup_buffers() was done */
		SSLerr(SSL_F_SSL3_GET_RECORD, ERR_R_INTERNAL_ERROR);
		return -1;
		}

again:
	/* check if we have the header */
	if (	(s->rstate != SSL_ST_READ_BODY) ||
		(s->packet_length < SSL3_RT_HEADER_LENGTH)) 
		{
		n=ssl3_read_n(s, SSL3_RT_HEADER_LENGTH, s->s3->rbuf.len, 0);
		if (n <= 0) return(n); /* error or non-blocking */
		s->rstate=SSL_ST_READ_BODY;

		p=s->packet;
		if (s->msg_callback)
			s->msg_callback(0, 0, SSL3_RT_HEADER, p, 5, s, s->msg_callback_arg);

		/* Pull apart the header into the SSL3_RECORD */
		rr->type= *(p++);
		ssl_major= *(p++);
		ssl_minor= *(p++);
		version=(ssl_major<<8)|ssl_minor;
		n2s(p,rr->length);
#if 0
fprintf(stderr, "Record type=%d, Length=%d\n", rr->type, rr->length);
#endif

		/* Lets check version */
		if (!s->first_packet)
			{
			if (version != s->version)
				{
				SSLerr(SSL_F_SSL3_GET_RECORD,SSL_R_WRONG_VERSION_NUMBER);
                                if ((s->version & 0xFF00) == (version & 0xFF00) && !s->enc_write_ctx && !s->write_hash)
                                	/* Send back error using their minor version number :-) */
					s->version = (unsigned short)version;
				al=SSL_AD_PROTOCOL_VERSION;
				goto f_err;
				}
			}

		if ((version>>8) != SSL3_VERSION_MAJOR)
			{
			SSLerr(SSL_F_SSL3_GET_RECORD,SSL_R_WRONG_VERSION_NUMBER);
			goto err;
			}

		if (rr->length > s->s3->rbuf.len - SSL3_RT_HEADER_LENGTH)
			{
			al=SSL_AD_RECORD_OVERFLOW;
			SSLerr(SSL_F_SSL3_GET_RECORD,SSL_R_PACKET_LENGTH_TOO_LONG);
			goto f_err;
			}

		/* now s->rstate == SSL_ST_READ_BODY */
		}

	/* s->rstate == SSL_ST_READ_BODY, get and decode the data */

	if (rr->length > s->packet_length-SSL3_RT_HEADER_LENGTH)
		{
		/* now s->packet_length == SSL3_RT_HEADER_LENGTH */
		i=rr->length;
		n=ssl3_read_n(s,i,i,1);
		if (n <= 0) return(n); /* error or non-blocking io */
		/* now n == rr->length,
		 * and s->packet_length == SSL3_RT_HEADER_LENGTH + rr->length */
		}

	s->rstate=SSL_ST_READ_HEADER; /* set state for later operations */

	/* 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[SSL3_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+extra)
		{
		al=SSL_AD_RECORD_OVERFLOW;
		SSLerr(SSL_F_SSL3_GET_RECORD,SSL_R_ENCRYPTED_LENGTH_TOO_LONG);
		goto f_err;
		}

	/* decrypt in place in 'rr->input' */
	rr->data=rr->input;
	rr->orig_len=rr->length;
	/* If in encrypt-then-mac mode calculate mac from encrypted record.
	 * All the details below are public so no timing details can leak.
	 */
	if (SSL_USE_ETM(s) && s->read_hash)
		{
		unsigned char *mac;
		mac_size=EVP_MD_CTX_size(s->read_hash);
		OPENSSL_assert(mac_size <= EVP_MAX_MD_SIZE);
		if (rr->length < mac_size)
			{
			al=SSL_AD_DECODE_ERROR;
			SSLerr(SSL_F_SSL3_GET_RECORD,SSL_R_LENGTH_TOO_SHORT);
			goto f_err;
			}
		rr->length -= mac_size;
		mac = rr->data + rr->length;
		i=s->method->ssl3_enc->mac(s,md,0 /* not send */);
		if (i < 0 || CRYPTO_memcmp(md, mac, (size_t)mac_size) != 0)
			{
			al=SSL_AD_BAD_RECORD_MAC;
			SSLerr(SSL_F_SSL3_GET_RECORD,SSL_R_DECRYPTION_FAILED_OR_BAD_RECORD_MAC);
			goto f_err;
			}
		}

	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)
		{
		al=SSL_AD_DECRYPTION_FAILED;
		SSLerr(SSL_F_SSL3_GET_RECORD,SSL_R_BLOCK_CIPHER_PAD_IS_WRONG);
		goto f_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) && !SSL_USE_ETM(s))
		{
		/* 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);

		/* 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 (rr->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 &&
		     rr->orig_len < mac_size+1))
			{
			al=SSL_AD_DECODE_ERROR;
			SSLerr(SSL_F_SSL3_GET_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);
			rr->length -= mac_size;
			}
		else
			{
			/* In this case there's no padding, so |rec->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+extra+mac_size)
			enc_err = -1;
		}

	if (enc_err < 0)
		{
		/* A separate 'decryption_failed' alert was introduced with TLS 1.0,
		 * SSL 3.0 only has 'bad_record_mac'.  But unless a decryption
		 * failure is directly visible from the ciphertext anyway,
		 * we should not reveal which kind of error occurred -- this
		 * might become visible to an attacker (e.g. via a logfile) */
		al=SSL_AD_BAD_RECORD_MAC;
		SSLerr(SSL_F_SSL3_GET_RECORD,SSL_R_DECRYPTION_FAILED_OR_BAD_RECORD_MAC);
		goto f_err;
		}

	/* r->length is now just compressed */
	if (s->expand != NULL)
		{
		if (rr->length > SSL3_RT_MAX_COMPRESSED_LENGTH+extra)
			{
			al=SSL_AD_RECORD_OVERFLOW;
			SSLerr(SSL_F_SSL3_GET_RECORD,SSL_R_COMPRESSED_LENGTH_TOO_LONG);
			goto f_err;
			}
		if (!ssl3_do_uncompress(s))
			{
			al=SSL_AD_DECOMPRESSION_FAILURE;
			SSLerr(SSL_F_SSL3_GET_RECORD,SSL_R_BAD_DECOMPRESSION);
			goto f_err;
			}
		}

	if (rr->length > SSL3_RT_MAX_PLAIN_LENGTH+extra)
		{
		al=SSL_AD_RECORD_OVERFLOW;
		SSLerr(SSL_F_SSL3_GET_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;

	/* just read a 0 length packet */
	if (rr->length == 0)
		{
		empty_record_count++;
		if (empty_record_count > MAX_EMPTY_RECORDS)
			{
			al=SSL_AD_UNEXPECTED_MESSAGE;
			SSLerr(SSL_F_SSL3_GET_RECORD,SSL_R_RECORD_TOO_SMALL);
			goto f_err;
			}
		goto again;
		}

#if 0
fprintf(stderr, "Ultimate Record type=%d, Length=%d\n", rr->type, rr->length);
#endif

	return(1);

f_err:
	ssl3_send_alert(s,SSL3_AL_FATAL,al);
err:
	return(ret);
	}

Project: openssl

int ssl3_write_bytes(SSL *s, int type, const void *buf_, int len)
	{
	const unsigned char *buf=buf_;
	int tot;
	unsigned int n,nw;
#if !defined(OPENSSL_NO_MULTIBLOCK) && EVP_CIPH_FLAG_TLS1_1_MULTIBLOCK
	unsigned int max_send_fragment;
#endif
	SSL3_BUFFER *wb=&(s->s3->wbuf);
	int i;
	unsigned int u_len = (unsigned int)len;

	if (len < 0)
		{
		SSLerr(SSL_F_SSL3_WRITE_BYTES,SSL_R_SSL_NEGATIVE_LENGTH);
		return -1;
		}

	s->rwstate=SSL_NOTHING;
	OPENSSL_assert(s->s3->wnum <= INT_MAX);
	tot=s->s3->wnum;
	s->s3->wnum=0;

	if (SSL_in_init(s) && !s->in_handshake)
		{
		i=s->handshake_func(s);
		if (i < 0) return(i);
		if (i == 0)
			{
			SSLerr(SSL_F_SSL3_WRITE_BYTES,SSL_R_SSL_HANDSHAKE_FAILURE);
			return -1;
			}
		}

	/* ensure that if we end up with a smaller value of data to write 
	 * out than the the original len from a write which didn't complete 
	 * for non-blocking I/O and also somehow ended up avoiding 
	 * the check for this in ssl3_write_pending/SSL_R_BAD_WRITE_RETRY as
	 * it must never be possible to end up with (len-tot) as a large
	 * number that will then promptly send beyond the end of the users
	 * buffer ... so we trap and report the error in a way the user
	 * will notice
	 */
	if (len < tot)
		{
		SSLerr(SSL_F_SSL3_WRITE_BYTES,SSL_R_BAD_LENGTH);
		return(-1);
		}

	/* first check if there is a SSL3_BUFFER still being written
	 * out.  This will happen with non blocking IO */
	if (wb->left != 0)
		{
		i = ssl3_write_pending(s,type,&buf[tot],s->s3->wpend_tot);
		if (i<=0)
			{
			/* XXX should we ssl3_release_write_buffer if i<0? */
			s->s3->wnum=tot;
			return i;
			}
		tot += i;	/* this might be last fragment */
		}

#if !defined(OPENSSL_NO_MULTIBLOCK) && EVP_CIPH_FLAG_TLS1_1_MULTIBLOCK
	/*
	 * Depending on platform multi-block can deliver several *times*
	 * better performance. Downside is that it has to allocate
	 * jumbo buffer to accomodate up to 8 records, but the
	 * compromise is considered worthy.
	 */
	if (type==SSL3_RT_APPLICATION_DATA &&
	    u_len >= 4*(max_send_fragment=s->max_send_fragment) &&
	    s->compress==NULL && s->msg_callback==NULL &&
	    !SSL_USE_ETM(s) && SSL_USE_EXPLICIT_IV(s) &&
	    EVP_CIPHER_flags(s->enc_write_ctx->cipher)&EVP_CIPH_FLAG_TLS1_1_MULTIBLOCK)
		{
		unsigned char aad[13];
		EVP_CTRL_TLS1_1_MULTIBLOCK_PARAM mb_param;
		int packlen;

		/* minimize address aliasing conflicts */
		if ((max_send_fragment&0xfff) == 0)
			max_send_fragment -= 512;

		if (tot==0 || wb->buf==NULL)	/* allocate jumbo buffer */
			{
			ssl3_release_write_buffer(s);

			packlen = EVP_CIPHER_CTX_ctrl(s->enc_write_ctx,
					EVP_CTRL_TLS1_1_MULTIBLOCK_MAX_BUFSIZE,
					max_send_fragment,NULL);

			if (u_len >= 8*max_send_fragment)	packlen *= 8;
			else				packlen *= 4;

			wb->buf=OPENSSL_malloc(packlen);
			wb->len=packlen;
			}
		else if (tot==len)		/* done? */
			{
			OPENSSL_free(wb->buf);	/* free jumbo buffer */
			wb->buf = NULL;
			return tot;
			}

		n=(len-tot);
		for (;;)
			{
			if (n < 4*max_send_fragment)
				{
				OPENSSL_free(wb->buf);	/* free jumbo buffer */
				wb->buf = NULL;
				break;
				}

			if (s->s3->alert_dispatch)
				{
				i=s->method->ssl_dispatch_alert(s);
				if (i <= 0)
					{
					s->s3->wnum=tot;
					return i;
					}
				}

			if (n >= 8*max_send_fragment)
				nw = max_send_fragment*(mb_param.interleave=8);
			else
				nw = max_send_fragment*(mb_param.interleave=4);

			memcpy(aad,s->s3->write_sequence,8);
			aad[8]=type;
			aad[9]=(unsigned char)(s->version>>8);
			aad[10]=(unsigned char)(s->version);
			aad[11]=0;
			aad[12]=0;
			mb_param.out = NULL;
			mb_param.inp = aad;
			mb_param.len = nw;

			packlen = EVP_CIPHER_CTX_ctrl(s->enc_write_ctx,
					EVP_CTRL_TLS1_1_MULTIBLOCK_AAD,
					sizeof(mb_param),&mb_param);

			if (packlen<=0 || packlen>(int)wb->len)	/* never happens */
				{
				OPENSSL_free(wb->buf);	/* free jumbo buffer */
				wb->buf = NULL;
				break;
				}

			mb_param.out = wb->buf;
			mb_param.inp = &buf[tot];
			mb_param.len = nw;

			if (EVP_CIPHER_CTX_ctrl(s->enc_write_ctx,
					EVP_CTRL_TLS1_1_MULTIBLOCK_ENCRYPT,
					sizeof(mb_param),&mb_param)<=0)
				return -1;

			s->s3->write_sequence[7] += mb_param.interleave;
			if (s->s3->write_sequence[7] < mb_param.interleave)
				{
				int j=6;
				while (j>=0 && (++s->s3->write_sequence[j--])==0) ;
				}

			wb->offset = 0;
			wb->left = packlen;

			s->s3->wpend_tot = nw;
			s->s3->wpend_buf = &buf[tot];
			s->s3->wpend_type= type;
			s->s3->wpend_ret = nw;

			i = ssl3_write_pending(s,type,&buf[tot],nw);
			if (i<=0)
				{
				if (i<0)
					{
					OPENSSL_free(wb->buf);
					wb->buf = NULL;
					}
				s->s3->wnum=tot;
				return i;
				}
			if (i==(int)n)
				{
				OPENSSL_free(wb->buf);	/* free jumbo buffer */
				wb->buf = NULL;
				return tot+i;
				}
			n-=i;
			tot+=i;
			}
		}
	else
#endif
	if (tot==len)		/* done? */
		{
		if (s->mode & SSL_MODE_RELEASE_BUFFERS &&
			!SSL_IS_DTLS(s))
			ssl3_release_write_buffer(s);

		return tot;
		}


	n=(len-tot);
	for (;;)
		{
		if (n > s->max_send_fragment)
			nw=s->max_send_fragment;
		else
			nw=n;

		i=do_ssl3_write(s, type, &(buf[tot]), nw, 0);
		if (i <= 0)
			{
			/* XXX should we ssl3_release_write_buffer if i<0? */
			s->s3->wnum=tot;
			return i;
			}

		if ((i == (int)n) ||
			(type == SSL3_RT_APPLICATION_DATA &&
			 (s->mode & SSL_MODE_ENABLE_PARTIAL_WRITE)))
			{
			/* next chunk of data should get another prepended empty fragment
			 * in ciphersuites with known-IV weakness: */
			s->s3->empty_fragment_done = 0;

			if ((i==(int)n) && s->mode & SSL_MODE_RELEASE_BUFFERS &&
				!SSL_IS_DTLS(s))
				ssl3_release_write_buffer(s);

			return tot+i;
			}

		n-=i;
		tot+=i;
		}
	}