IABSD.fr/src/lib/libssl/ssl_ciphers.c

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• Author : bcook
  Date : 2019-05-15 09:13:16
  Hash : 370b9647
  Message : s3 is never NULL since s2 (formerly used for SSLv2) does not exist, so there is no need to check for it. Fixes COV-165788, identified with help from Alex Bumstead. ok jsing@

• lib/libssl/ssl_ciphers.c

• /*	$OpenBSD: ssl_ciphers.c,v 1.3 2019/05/15 09:13:16 bcook Exp $ */
  /*
   * Copyright (c) 2015-2017 Doug Hogan <doug@openbsd.org>
   * Copyright (c) 2015-2018 Joel Sing <jsing@openbsd.org>
   * Copyright (c) 2019 Theo Buehler <tb@openbsd.org>
   *
   * Permission to use, copy, modify, and distribute this software for any
   * purpose with or without fee is hereby granted, provided that the above
   * copyright notice and this permission notice appear in all copies.
   *
   * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
   * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
   * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
   * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
   * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
   * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
   * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
   */
  
  #include <openssl/safestack.h>
  
  #include "bytestring.h"
  #include "ssl_locl.h"
  
  int
  ssl_cipher_is_permitted(const SSL_CIPHER *cipher, uint16_t min_ver,
      uint16_t max_ver)
  {
  	/* XXX: We only support DTLSv1 which is effectively TLSv1.1 */
  	if (min_ver == DTLS1_VERSION || max_ver == DTLS1_VERSION)
  		min_ver = max_ver = TLS1_1_VERSION;
  
  	switch(cipher->algorithm_ssl) {
  	case SSL_SSLV3:
  		if (min_ver <= TLS1_2_VERSION)
  			return 1;
  		break;
  	case SSL_TLSV1_2:
  		if (min_ver <= TLS1_2_VERSION && TLS1_2_VERSION <= max_ver)
  			return 1;
  		break;
  	case SSL_TLSV1_3:
  		if (min_ver <= TLS1_3_VERSION && TLS1_3_VERSION <= max_ver)
  			return 1;
  		break;
  	}
  
  	return 0;
  }
  
  int
  ssl_cipher_list_to_bytes(SSL *s, STACK_OF(SSL_CIPHER) *ciphers, CBB *cbb)
  {
  	SSL_CIPHER *cipher;
  	int num_ciphers = 0;
  	uint16_t min_vers, max_vers;
  	int i;
  
  	if (ciphers == NULL)
  		return 0;
  
  	if (!ssl_supported_version_range(s, &min_vers, &max_vers))
  		return 0;
  
  	for (i = 0; i < sk_SSL_CIPHER_num(ciphers); i++) {
  		if ((cipher = sk_SSL_CIPHER_value(ciphers, i)) == NULL)
  			return 0;
  
  		if (!ssl_cipher_is_permitted(cipher, min_vers, max_vers))
  			continue;
  
  		if (!CBB_add_u16(cbb, ssl3_cipher_get_value(cipher)))
  			return 0;
  
  		num_ciphers++;
  	}
  
  	/* Add SCSV if there are other ciphers and we're not renegotiating. */
  	if (num_ciphers > 0 && !s->internal->renegotiate) {
  		if (!CBB_add_u16(cbb, SSL3_CK_SCSV & SSL3_CK_VALUE_MASK))
  			return 0;
  	}
  
  	if (!CBB_flush(cbb))
  		return 0;
  
  	return 1;
  }
  
  STACK_OF(SSL_CIPHER) *
  ssl_bytes_to_cipher_list(SSL *s, CBS *cbs)
  {
  	STACK_OF(SSL_CIPHER) *ciphers = NULL;
  	const SSL_CIPHER *cipher;
  	uint16_t cipher_value, max_version;
  	unsigned long cipher_id;
  
  	S3I(s)->send_connection_binding = 0;
  
  	if ((ciphers = sk_SSL_CIPHER_new_null()) == NULL) {
  		SSLerror(s, ERR_R_MALLOC_FAILURE);
  		goto err;
  	}
  
  	while (CBS_len(cbs) > 0) {
  		if (!CBS_get_u16(cbs, &cipher_value)) {
  			SSLerror(s, SSL_R_ERROR_IN_RECEIVED_CIPHER_LIST);
  			goto err;
  		}
  
  		cipher_id = SSL3_CK_ID | cipher_value;
  
  		if (cipher_id == SSL3_CK_SCSV) {
  			/*
  			 * TLS_EMPTY_RENEGOTIATION_INFO_SCSV is fatal if
  			 * renegotiating.
  			 */
  			if (s->internal->renegotiate) {
  				SSLerror(s, SSL_R_SCSV_RECEIVED_WHEN_RENEGOTIATING);
  				ssl3_send_alert(s, SSL3_AL_FATAL,
  				    SSL_AD_HANDSHAKE_FAILURE);
  
  				goto err;
  			}
  			S3I(s)->send_connection_binding = 1;
  			continue;
  		}
  
  		if (cipher_id == SSL3_CK_FALLBACK_SCSV) {
  			/*
  			 * TLS_FALLBACK_SCSV indicates that the client
  			 * previously tried a higher protocol version.
  			 * Fail if the current version is an unexpected
  			 * downgrade.
  			 */
  			max_version = ssl_max_server_version(s);
  			if (max_version == 0 || s->version < max_version) {
  				SSLerror(s, SSL_R_INAPPROPRIATE_FALLBACK);
  				ssl3_send_alert(s, SSL3_AL_FATAL,
  					SSL_AD_INAPPROPRIATE_FALLBACK);
  				goto err;
  			}
  			continue;
  		}
  
  		if ((cipher = ssl3_get_cipher_by_value(cipher_value)) != NULL) {
  			if (!sk_SSL_CIPHER_push(ciphers, cipher)) {
  				SSLerror(s, ERR_R_MALLOC_FAILURE);
  				goto err;
  			}
  		}
  	}
  
  	return (ciphers);
  
   err:
  	sk_SSL_CIPHER_free(ciphers);
  
  	return (NULL);
  }