text: /* $OpenBSD: ssl_asn1.c,v 1.57 2018/08/27 16:42:48 jsing Exp $ */
  /*
   * Copyright (c) 2016 Joel Sing <jsing@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 <limits.h>
  
  #include <openssl/ssl.h>
  #include <openssl/x509.h>
  
  #include "ssl_locl.h"
  
  #include "bytestring.h"
  
  #define SSLASN1_TAG	(CBS_ASN1_CONSTRUCTED | CBS_ASN1_CONTEXT_SPECIFIC)
  #define SSLASN1_TIME_TAG		(SSLASN1_TAG | 1)
  #define SSLASN1_TIMEOUT_TAG		(SSLASN1_TAG | 2)
  #define SSLASN1_PEER_CERT_TAG		(SSLASN1_TAG | 3)
  #define SSLASN1_SESSION_ID_CTX_TAG	(SSLASN1_TAG | 4)
  #define SSLASN1_VERIFY_RESULT_TAG	(SSLASN1_TAG | 5)
  #define SSLASN1_HOSTNAME_TAG		(SSLASN1_TAG | 6)
  #define SSLASN1_LIFETIME_TAG		(SSLASN1_TAG | 9)
  #define SSLASN1_TICKET_TAG		(SSLASN1_TAG | 10)
  
  static uint64_t
  time_max(void)
  {
  	if (sizeof(time_t) == sizeof(int32_t))
  		return INT32_MAX;
  	if (sizeof(time_t) == sizeof(int64_t))
  		return INT64_MAX;
  	return 0;
  }
  
  static int
  SSL_SESSION_encode(SSL_SESSION *s, unsigned char **out, size_t *out_len,
      int ticket_encoding)
  {
  	CBB cbb, session, cipher_suite, session_id, master_key, time, timeout;
  	CBB peer_cert, sidctx, verify_result, hostname, lifetime, ticket, value;
  	unsigned char *peer_cert_bytes = NULL;
  	int len, rv = 0;
  	uint16_t cid;
  
  	if (!CBB_init(&cbb, 0))
  		goto err;
  
  	if (!CBB_add_asn1(&cbb, &session, CBS_ASN1_SEQUENCE))
  		goto err;
  
  	/* Session ASN1 version. */
  	if (!CBB_add_asn1_uint64(&session, SSL_SESSION_ASN1_VERSION))
  		goto err;
  
  	/* TLS/SSL protocol version. */
  	if (s->ssl_version < 0)
  		goto err;
  	if (!CBB_add_asn1_uint64(&session, s->ssl_version))
  		goto err;
  
  	/* Cipher suite ID. */
  	/* XXX - require cipher to be non-NULL or always/only use cipher_id. */
  	cid = (uint16_t)(s->cipher_id & 0xffff);
  	if (s->cipher != NULL)
  		cid = ssl3_cipher_get_value(s->cipher);
  	if (!CBB_add_asn1(&session, &cipher_suite, CBS_ASN1_OCTETSTRING))
  		goto err;
  	if (!CBB_add_u16(&cipher_suite, cid))
  		goto err;
  
  	/* Session ID - zero length for a ticket. */
  	if (!CBB_add_asn1(&session, &session_id, CBS_ASN1_OCTETSTRING))
  		goto err;
  	if (!CBB_add_bytes(&session_id, s->session_id,
  	    ticket_encoding ? 0 : s->session_id_length))
  		goto err;
  
  	/* Master key. */
  	if (!CBB_add_asn1(&session, &master_key, CBS_ASN1_OCTETSTRING))
  		goto err;
  	if (!CBB_add_bytes(&master_key, s->master_key, s->master_key_length))
  		goto err;
  
  	/* Time [1]. */
  	if (s->time != 0) {
  		if (s->time < 0)
  			goto err;
  		if (!CBB_add_asn1(&session, &time, SSLASN1_TIME_TAG))
  			goto err;
  		if (!CBB_add_asn1_uint64(&time, s->time))
  			goto err;
  	}
  
  	/* Timeout [2]. */
  	if (s->timeout != 0) {
  		if (s->timeout < 0)
  			goto err;
  		if (!CBB_add_asn1(&session, &timeout, SSLASN1_TIMEOUT_TAG))
  			goto err;
  		if (!CBB_add_asn1_uint64(&timeout, s->timeout))
  			goto err;
  	}
  
  	/* Peer certificate [3]. */
  	if (s->peer != NULL) {
  		if ((len = i2d_X509(s->peer, &peer_cert_bytes)) <= 0)
  			goto err;
  		if (!CBB_add_asn1(&session, &peer_cert, SSLASN1_PEER_CERT_TAG))
  			goto err;
  		if (!CBB_add_bytes(&peer_cert, peer_cert_bytes, len))
  			goto err;
  	}
  
  	/* Session ID context [4]. */
  	/* XXX - Actually handle this as optional? */
  	if (!CBB_add_asn1(&session, &sidctx, SSLASN1_SESSION_ID_CTX_TAG))
  		goto err;
  	if (!CBB_add_asn1(&sidctx, &value, CBS_ASN1_OCTETSTRING))
  		goto err;
  	if (!CBB_add_bytes(&value, s->sid_ctx, s->sid_ctx_length))
  		goto err;
  
  	/* Verify result [5]. */
  	if (s->verify_result != X509_V_OK) {
  		if (s->verify_result < 0)
  			goto err;
  		if (!CBB_add_asn1(&session, &verify_result,
  		    SSLASN1_VERIFY_RESULT_TAG))
  			goto err;
  		if (!CBB_add_asn1_uint64(&verify_result, s->verify_result))
  			goto err;
  	}
  
  	/* Hostname [6]. */
  	if (s->tlsext_hostname != NULL) {
  		if (!CBB_add_asn1(&session, &hostname, SSLASN1_HOSTNAME_TAG))
  			goto err;
  		if (!CBB_add_asn1(&hostname, &value, CBS_ASN1_OCTETSTRING))
  			goto err;
  		if (!CBB_add_bytes(&value, (const uint8_t *)s->tlsext_hostname,
  		    strlen(s->tlsext_hostname)))
  			goto err;
  	}
  
  	/* PSK identity hint [7]. */
  	/* PSK identity [8]. */
  
  	/* Ticket lifetime hint [9]. */
  	if (s->tlsext_tick_lifetime_hint > 0) {
  		if (!CBB_add_asn1(&session, &lifetime, SSLASN1_LIFETIME_TAG))
  			goto err;
  		if (!CBB_add_asn1_uint64(&lifetime,
  		    s->tlsext_tick_lifetime_hint))
  			goto err;
  	}
  
  	/* Ticket [10]. */
  	if (s->tlsext_tick != NULL) {
  		if (!CBB_add_asn1(&session, &ticket, SSLASN1_TICKET_TAG))
  			goto err;
  		if (!CBB_add_asn1(&ticket, &value, CBS_ASN1_OCTETSTRING))
  			goto err;
  		if (!CBB_add_bytes(&value, s->tlsext_tick, s->tlsext_ticklen))
  			goto err;
  	}
  
  	/* Compression method [11]. */
  	/* SRP username [12]. */
  
  	if (!CBB_finish(&cbb, out, out_len))
  		goto err;
  
  	rv = 1;
  
   err:
  	CBB_cleanup(&cbb);
  	free(peer_cert_bytes);
  
  	return rv;
  }
  
  int
  SSL_SESSION_ticket(SSL_SESSION *ss, unsigned char **out, size_t *out_len)
  {
  	if (ss == NULL)
  		return 0;
  
  	if (ss->cipher == NULL && ss->cipher_id == 0)
  		return 0;
  
  	return SSL_SESSION_encode(ss, out, out_len, 1);
  }
  
  int
  i2d_SSL_SESSION(SSL_SESSION *ss, unsigned char **pp)
  {
  	unsigned char *data = NULL;
  	size_t data_len = 0;
  	int rv = -1;
  
  	if (ss == NULL)
  		return 0;
  
  	if (ss->cipher == NULL && ss->cipher_id == 0)
  		return 0;
  
  	if (!SSL_SESSION_encode(ss, &data, &data_len, 0))
  		goto err;
  
  	if (data_len > INT_MAX)
  		goto err;
  
  	if (pp != NULL) {
  		if (*pp == NULL) {
  			*pp = data;
  			data = NULL;
  		} else {
  			memcpy(*pp, data, data_len);
  			*pp += data_len;
  		}
  	}
  
  	rv = (int)data_len;
  
   err:
  	freezero(data, data_len);
  
  	return rv;
  }
  
  SSL_SESSION *
  d2i_SSL_SESSION(SSL_SESSION **a, const unsigned char **pp, long length)
  {
  	CBS cbs, session, cipher_suite, session_id, master_key, peer_cert;
  	CBS hostname, ticket;
  	uint64_t version, tls_version, stime, timeout, verify_result, lifetime;
  	const unsigned char *peer_cert_bytes;
  	uint16_t cipher_value;
  	SSL_SESSION *s = NULL;
  	size_t data_len;
  	int present;
  
  	if (a != NULL)
  		s = *a;
  
  	if (s == NULL) {
  		if ((s = SSL_SESSION_new()) == NULL) {
  			SSLerrorx(ERR_R_MALLOC_FAILURE);
  			return (NULL);
  		}
  	}
  
  	CBS_init(&cbs, *pp, length);
  
  	if (!CBS_get_asn1(&cbs, &session, CBS_ASN1_SEQUENCE))
  		goto err;
  
  	/* Session ASN1 version. */
  	if (!CBS_get_asn1_uint64(&session, &version))
  		goto err;
  	if (version != SSL_SESSION_ASN1_VERSION)
  		goto err;
  
  	/* TLS/SSL Protocol Version. */
  	if (!CBS_get_asn1_uint64(&session, &tls_version))
  		goto err;
  	if (tls_version > INT_MAX)
  		goto err;
  	s->ssl_version = (int)tls_version;
  
  	/* Cipher suite. */
  	if (!CBS_get_asn1(&session, &cipher_suite, CBS_ASN1_OCTETSTRING))
  		goto err;
  	if (!CBS_get_u16(&cipher_suite, &cipher_value))
  		goto err;
  	if (CBS_len(&cipher_suite) != 0)
  		goto err;
  
  	/* XXX - populate cipher instead? */
  	s->cipher = NULL;
  	s->cipher_id = SSL3_CK_ID | cipher_value;
  
  	/* Session ID. */
  	if (!CBS_get_asn1(&session, &session_id, CBS_ASN1_OCTETSTRING))
  		goto err;
  	if (!CBS_write_bytes(&session_id, s->session_id, sizeof(s->session_id),
  	    &data_len))
  		goto err;
  	if (data_len > UINT_MAX)
  		goto err;
  	s->session_id_length = (unsigned int)data_len;
  
  	/* Master key. */
  	if (!CBS_get_asn1(&session, &master_key, CBS_ASN1_OCTETSTRING))
  		goto err;
  	if (!CBS_write_bytes(&master_key, s->master_key, sizeof(s->master_key),
  	    &data_len))
  		goto err;
  	if (data_len > INT_MAX)
  		goto err;
  	s->master_key_length = (int)data_len;
  
  	/* Time [1]. */
  	s->time = time(NULL);
  	if (!CBS_get_optional_asn1_uint64(&session, &stime, SSLASN1_TIME_TAG,
  	    0))
  		goto err;
  	if (stime > time_max())
  		goto err;
  	if (stime != 0)
  		s->time = (time_t)stime;
  
  	/* Timeout [2]. */
  	s->timeout = 3;
  	if (!CBS_get_optional_asn1_uint64(&session, &timeout,
  	    SSLASN1_TIMEOUT_TAG, 0))
  		goto err;
  	if (timeout > LONG_MAX)
  		goto err;
  	if (timeout != 0)
  		s->timeout = (long)timeout;
  	
  	/* Peer certificate [3]. */
  	X509_free(s->peer);
  	s->peer = NULL;
  	if (!CBS_get_optional_asn1(&session, &peer_cert, &present,
  	    SSLASN1_PEER_CERT_TAG))
  		goto err;
  	if (present) {
  		data_len = CBS_len(&peer_cert);
  		if (data_len > LONG_MAX)
  			goto err;
  		peer_cert_bytes = CBS_data(&peer_cert);
  		if (d2i_X509(&s->peer, &peer_cert_bytes,
  		    (long)data_len) == NULL)
  			goto err;
  	}
  
  	/* Session ID context [4]. */
  	s->sid_ctx_length = 0;
  	if (!CBS_get_optional_asn1_octet_string(&session, &session_id, &present,
  	    SSLASN1_SESSION_ID_CTX_TAG))
  		goto err;
  	if (present) {
  		if (!CBS_write_bytes(&session_id, (uint8_t *)&s->sid_ctx,
  		    sizeof(s->sid_ctx), &data_len))
  			goto err;
  		if (data_len > UINT_MAX)
  			goto err;
  		s->sid_ctx_length = (unsigned int)data_len;
  	}
  
  	/* Verify result [5]. */
  	s->verify_result = X509_V_OK;
  	if (!CBS_get_optional_asn1_uint64(&session, &verify_result,
  	    SSLASN1_VERIFY_RESULT_TAG, X509_V_OK))
  		goto err;
  	if (verify_result > LONG_MAX)
  		goto err;
  	s->verify_result = (long)verify_result;
  
  	/* Hostname [6]. */
  	free(s->tlsext_hostname);
  	s->tlsext_hostname = NULL;
  	if (!CBS_get_optional_asn1_octet_string(&session, &hostname, &present,
  	    SSLASN1_HOSTNAME_TAG))
  		goto err;
  	if (present) {
  		if (CBS_contains_zero_byte(&hostname))
  			goto err;
  		if (!CBS_strdup(&hostname, &s->tlsext_hostname))
  			goto err;
  	}
  	
  	/* PSK identity hint [7]. */
  	/* PSK identity [8]. */
  
  	/* Ticket lifetime [9]. */
  	s->tlsext_tick_lifetime_hint = 0;
  	/* XXX - tlsext_ticklen is not yet set... */
  	if (s->tlsext_ticklen > 0 && s->session_id_length > 0)
  		s->tlsext_tick_lifetime_hint = -1;
  	if (!CBS_get_optional_asn1_uint64(&session, &lifetime,
  	    SSLASN1_LIFETIME_TAG, 0))
  		goto err;
  	if (lifetime > LONG_MAX)
  		goto err;
  	if (lifetime > 0)
  		s->tlsext_tick_lifetime_hint = (long)lifetime;
  
  	/* Ticket [10]. */
  	free(s->tlsext_tick);
  	s->tlsext_tick = NULL;
  	if (!CBS_get_optional_asn1_octet_string(&session, &ticket, &present,
  	    SSLASN1_TICKET_TAG))
  		goto err;
  	if (present) {
  		if (!CBS_stow(&ticket, &s->tlsext_tick, &s->tlsext_ticklen))
  			goto err;
  	}
  
  	/* Compression method [11]. */
  	/* SRP username [12]. */
  
  	*pp = CBS_data(&cbs);
  
  	if (a != NULL)
  		*a = s;
  
  	return (s);
  
  err:
  	ERR_asprintf_error_data("offset=%d", (int)(CBS_data(&cbs) - *pp));
  
  	if (s != NULL && (a == NULL || *a != s))
  		SSL_SESSION_free(s);
  
  	return (NULL);
  }
  