pineapple/externals/libressl/ssl/tls13_key_schedule.c

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2020-12-28 16:15:37 +01:00
/* $OpenBSD: tls13_key_schedule.c,v 1.8 2019/11/17 21:01:08 beck Exp $ */
/* Copyright (c) 2018, Bob Beck <beck@openbsd.org>
*
* Permission to use, copy, modify, and/or 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 <string.h>
#include <stdlib.h>
#include <openssl/hkdf.h>
#include "bytestring.h"
#include "tls13_internal.h"
void
tls13_secrets_destroy(struct tls13_secrets *secrets)
{
if (secrets == NULL)
return;
/* you can never be too sure :) */
freezero(secrets->zeros.data, secrets->zeros.len);
freezero(secrets->empty_hash.data, secrets->empty_hash.len);
freezero(secrets->extracted_early.data,
secrets->extracted_early.len);
freezero(secrets->binder_key.data,
secrets->binder_key.len);
freezero(secrets->client_early_traffic.data,
secrets->client_early_traffic.len);
freezero(secrets->early_exporter_master.data,
secrets->early_exporter_master.len);
freezero(secrets->derived_early.data,
secrets->derived_early.len);
freezero(secrets->extracted_handshake.data,
secrets->extracted_handshake.len);
freezero(secrets->client_handshake_traffic.data,
secrets->client_handshake_traffic.len);
freezero(secrets->server_handshake_traffic.data,
secrets->server_handshake_traffic.len);
freezero(secrets->derived_handshake.data,
secrets->derived_handshake.len);
freezero(secrets->extracted_master.data,
secrets->extracted_master.len);
freezero(secrets->client_application_traffic.data,
secrets->client_application_traffic.len);
freezero(secrets->server_application_traffic.data,
secrets->server_application_traffic.len);
freezero(secrets->exporter_master.data,
secrets->exporter_master.len);
freezero(secrets->resumption_master.data,
secrets->resumption_master.len);
freezero(secrets, sizeof(struct tls13_secrets));
}
/*
* Allocate a set of secrets for a key schedule using
* a size of hash_length from RFC 8446 section 7.1.
*/
struct tls13_secrets *
tls13_secrets_create(const EVP_MD *digest, int resumption)
{
struct tls13_secrets *secrets = NULL;
EVP_MD_CTX *mdctx = NULL;
unsigned int mdlen;
size_t hash_length;
hash_length = EVP_MD_size(digest);
if ((secrets = calloc(1, sizeof(struct tls13_secrets))) == NULL)
goto err;
if ((secrets->zeros.data = calloc(hash_length, sizeof(uint8_t))) ==
NULL)
goto err;
secrets->zeros.len = hash_length;
if ((secrets->empty_hash.data = malloc(hash_length)) == NULL)
goto err;
secrets->empty_hash.len = hash_length;
if ((secrets->extracted_early.data = malloc(hash_length)) == NULL)
goto err;
secrets->extracted_early.len = hash_length;
if ((secrets->binder_key.data = malloc(hash_length)) == NULL)
goto err;
secrets->binder_key.len = hash_length;
if ((secrets->client_early_traffic.data = malloc(hash_length)) == NULL)
goto err;
secrets->client_early_traffic.len = hash_length;
if ((secrets->early_exporter_master.data = malloc(hash_length)) ==
NULL)
goto err;
secrets->early_exporter_master.len = hash_length;
if ((secrets->derived_early.data = malloc(hash_length)) == NULL)
goto err;
secrets->derived_early.len = hash_length;
if ((secrets->extracted_handshake.data = malloc(hash_length)) == NULL)
goto err;
secrets->extracted_handshake.len = hash_length;
if ((secrets->client_handshake_traffic.data = malloc(hash_length))
== NULL)
goto err;
secrets->client_handshake_traffic.len = hash_length;
if ((secrets->server_handshake_traffic.data = malloc(hash_length))
== NULL)
goto err;
secrets->server_handshake_traffic.len = hash_length;
if ((secrets->derived_handshake.data = malloc(hash_length)) == NULL)
goto err;
secrets->derived_handshake.len = hash_length;
if ((secrets->extracted_master.data = malloc(hash_length)) == NULL)
goto err;
secrets->extracted_master.len = hash_length;
if ((secrets->client_application_traffic.data = malloc(hash_length)) ==
NULL)
goto err;
secrets->client_application_traffic.len = hash_length;
if ((secrets->server_application_traffic.data = malloc(hash_length)) ==
NULL)
goto err;
secrets->server_application_traffic.len = hash_length;
if ((secrets->exporter_master.data = malloc(hash_length)) == NULL)
goto err;
secrets->exporter_master.len = hash_length;
if ((secrets->resumption_master.data = malloc(hash_length)) == NULL)
goto err;
secrets->resumption_master.len = hash_length;
/*
* Calculate the hash of a zero-length string - this is needed during
* the "derived" step for key extraction.
*/
if ((mdctx = EVP_MD_CTX_new()) == NULL)
goto err;
if (!EVP_DigestInit_ex(mdctx, digest, NULL))
goto err;
if (!EVP_DigestUpdate(mdctx, secrets->zeros.data, 0))
goto err;
if (!EVP_DigestFinal_ex(mdctx, secrets->empty_hash.data, &mdlen))
goto err;
EVP_MD_CTX_free(mdctx);
mdctx = NULL;
if (secrets->empty_hash.len != mdlen)
goto err;
secrets->digest = digest;
secrets->resumption = resumption;
secrets->init_done = 1;
return secrets;
err:
tls13_secrets_destroy(secrets);
EVP_MD_CTX_free(mdctx);
return NULL;
}
int
tls13_hkdf_expand_label(struct tls13_secret *out, const EVP_MD *digest,
const struct tls13_secret *secret, const char *label,
const struct tls13_secret *context)
{
const char tls13_plabel[] = "tls13 ";
uint8_t *hkdf_label;
size_t hkdf_label_len;
CBB cbb, child;
int ret;
if (!CBB_init(&cbb, 256))
return 0;
if (!CBB_add_u16(&cbb, out->len))
goto err;
if (!CBB_add_u8_length_prefixed(&cbb, &child))
goto err;
if (!CBB_add_bytes(&child, tls13_plabel, strlen(tls13_plabel)))
goto err;
if (!CBB_add_bytes(&child, label, strlen(label)))
goto err;
if (!CBB_add_u8_length_prefixed(&cbb, &child))
goto err;
if (!CBB_add_bytes(&child, context->data, context->len))
goto err;
if (!CBB_finish(&cbb, &hkdf_label, &hkdf_label_len))
goto err;
ret = HKDF_expand(out->data, out->len, digest, secret->data,
secret->len, hkdf_label, hkdf_label_len);
free(hkdf_label);
return(ret);
err:
CBB_cleanup(&cbb);
return(0);
}
static int
tls13_derive_secret(struct tls13_secret *out, const EVP_MD *digest,
const struct tls13_secret *secret, const char *label,
const struct tls13_secret *context)
{
return tls13_hkdf_expand_label(out, digest, secret, label, context);
}
int
tls13_derive_early_secrets(struct tls13_secrets *secrets,
uint8_t *psk, size_t psk_len, const struct tls13_secret *context)
{
if (!secrets->init_done || secrets->early_done)
return 0;
if (!HKDF_extract(secrets->extracted_early.data,
&secrets->extracted_early.len, secrets->digest, psk, psk_len,
secrets->zeros.data, secrets->zeros.len))
return 0;
if (secrets->extracted_early.len != secrets->zeros.len)
return 0;
if (!tls13_derive_secret(&secrets->binder_key, secrets->digest,
&secrets->extracted_early,
secrets->resumption ? "res binder" : "ext binder",
&secrets->empty_hash))
return 0;
if (!tls13_derive_secret(&secrets->client_early_traffic,
secrets->digest, &secrets->extracted_early, "c e traffic",
context))
return 0;
if (!tls13_derive_secret(&secrets->early_exporter_master,
secrets->digest, &secrets->extracted_early, "e exp master",
context))
return 0;
if (!tls13_derive_secret(&secrets->derived_early,
secrets->digest, &secrets->extracted_early, "derived",
&secrets->empty_hash))
return 0;
/* RFC 8446 recommends */
if (!secrets->insecure)
explicit_bzero(secrets->extracted_early.data,
secrets->extracted_early.len);
secrets->early_done = 1;
return 1;
}
int
tls13_derive_handshake_secrets(struct tls13_secrets *secrets,
const uint8_t *ecdhe, size_t ecdhe_len,
const struct tls13_secret *context)
{
if (!secrets->init_done || !secrets->early_done ||
secrets->handshake_done)
return 0;
if (!HKDF_extract(secrets->extracted_handshake.data,
&secrets->extracted_handshake.len, secrets->digest,
ecdhe, ecdhe_len, secrets->derived_early.data,
secrets->derived_early.len))
return 0;
if (secrets->extracted_handshake.len != secrets->zeros.len)
return 0;
/* XXX */
if (!secrets->insecure)
explicit_bzero(secrets->derived_early.data,
secrets->derived_early.len);
if (!tls13_derive_secret(&secrets->client_handshake_traffic,
secrets->digest, &secrets->extracted_handshake, "c hs traffic",
context))
return 0;
if (!tls13_derive_secret(&secrets->server_handshake_traffic,
secrets->digest, &secrets->extracted_handshake, "s hs traffic",
context))
return 0;
if (!tls13_derive_secret(&secrets->derived_handshake,
secrets->digest, &secrets->extracted_handshake, "derived",
&secrets->empty_hash))
return 0;
/* RFC 8446 recommends */
if (!secrets->insecure)
explicit_bzero(secrets->extracted_handshake.data,
secrets->extracted_handshake.len);
secrets->handshake_done = 1;
return 1;
}
int
tls13_derive_application_secrets(struct tls13_secrets *secrets,
const struct tls13_secret *context)
{
if (!secrets->init_done || !secrets->early_done ||
!secrets->handshake_done || secrets->schedule_done)
return 0;
if (!HKDF_extract(secrets->extracted_master.data,
&secrets->extracted_master.len, secrets->digest,
secrets->zeros.data, secrets->zeros.len,
secrets->derived_handshake.data, secrets->derived_handshake.len))
return 0;
if (secrets->extracted_master.len != secrets->zeros.len)
return 0;
/* XXX */
if (!secrets->insecure)
explicit_bzero(secrets->derived_handshake.data,
secrets->derived_handshake.len);
if (!tls13_derive_secret(&secrets->client_application_traffic,
secrets->digest, &secrets->extracted_master, "c ap traffic",
context))
return 0;
if (!tls13_derive_secret(&secrets->server_application_traffic,
secrets->digest, &secrets->extracted_master, "s ap traffic",
context))
return 0;
if (!tls13_derive_secret(&secrets->exporter_master,
secrets->digest, &secrets->extracted_master, "exp master",
context))
return 0;
if (!tls13_derive_secret(&secrets->resumption_master,
secrets->digest, &secrets->extracted_master, "res master",
context))
return 0;
/* RFC 8446 recommends */
if (!secrets->insecure)
explicit_bzero(secrets->extracted_master.data,
secrets->extracted_master.len);
secrets->schedule_done = 1;
return 1;
}
int
tls13_update_client_traffic_secret(struct tls13_secrets *secrets)
{
struct tls13_secret context = { .data = "", .len = 0 };
if (!secrets->init_done || !secrets->early_done ||
!secrets->handshake_done || !secrets->schedule_done)
return 0;
return tls13_hkdf_expand_label(&secrets->client_application_traffic,
secrets->digest, &secrets->client_application_traffic,
"traffic upd", &context);
}
int
tls13_update_server_traffic_secret(struct tls13_secrets *secrets)
{
struct tls13_secret context = { .data = "", .len = 0 };
if (!secrets->init_done || !secrets->early_done ||
!secrets->handshake_done || !secrets->schedule_done)
return 0;
return tls13_hkdf_expand_label(&secrets->server_application_traffic,
secrets->digest, &secrets->server_application_traffic,
"traffic upd", &context);
}