From 35e7c2f41633d153898933e5ba6cf0580ce70f26 Mon Sep 17 00:00:00 2001 From: tb <> Date: Wed, 6 Jan 2021 20:15:35 +0000 Subject: Use tls13_secret_{init,cleanup}() for the finished_key This trades an array on the stack for a dynamically allocated secret in tls13_{client,server}_finished_send() but has the benefit of wiping out an intermediate secret on function exit. ok jsing --- src/lib/libssl/tls13_client.c | 10 +++++----- src/lib/libssl/tls13_server.c | 10 +++++----- 2 files changed, 10 insertions(+), 10 deletions(-) (limited to 'src/lib') diff --git a/src/lib/libssl/tls13_client.c b/src/lib/libssl/tls13_client.c index 25d78d1332..1f51748147 100644 --- a/src/lib/libssl/tls13_client.c +++ b/src/lib/libssl/tls13_client.c @@ -1,4 +1,4 @@ -/* $OpenBSD: tls13_client.c,v 1.69 2021/01/05 17:32:39 jsing Exp $ */ +/* $OpenBSD: tls13_client.c,v 1.70 2021/01/06 20:15:35 tb Exp $ */ /* * Copyright (c) 2018, 2019 Joel Sing * @@ -1034,10 +1034,9 @@ tls13_client_finished_send(struct tls13_ctx *ctx, CBB *cbb) { struct tls13_secrets *secrets = ctx->hs->secrets; struct tls13_secret context = { .data = "", .len = 0 }; - struct tls13_secret finished_key; + struct tls13_secret finished_key = { .data = NULL, .len = 0 }; uint8_t transcript_hash[EVP_MAX_MD_SIZE]; size_t transcript_hash_len; - uint8_t key[EVP_MAX_MD_SIZE]; uint8_t *verify_data; size_t verify_data_len; unsigned int hlen; @@ -1046,8 +1045,8 @@ tls13_client_finished_send(struct tls13_ctx *ctx, CBB *cbb) SSL *s = ctx->ssl; int ret = 0; - finished_key.data = key; - finished_key.len = EVP_MD_size(ctx->hash); + if (!tls13_secret_init(&finished_key, EVP_MD_size(ctx->hash))) + goto err; if (!tls13_hkdf_expand_label(&finished_key, ctx->hash, &secrets->client_handshake_traffic, "finished", @@ -1082,6 +1081,7 @@ tls13_client_finished_send(struct tls13_ctx *ctx, CBB *cbb) ret = 1; err: + tls13_secret_cleanup(&finished_key); HMAC_CTX_free(hmac_ctx); return ret; diff --git a/src/lib/libssl/tls13_server.c b/src/lib/libssl/tls13_server.c index 9e5664b79a..f929e132a8 100644 --- a/src/lib/libssl/tls13_server.c +++ b/src/lib/libssl/tls13_server.c @@ -1,4 +1,4 @@ -/* $OpenBSD: tls13_server.c,v 1.66 2021/01/05 17:32:39 jsing Exp $ */ +/* $OpenBSD: tls13_server.c,v 1.67 2021/01/06 20:15:35 tb Exp $ */ /* * Copyright (c) 2019, 2020 Joel Sing * Copyright (c) 2020 Bob Beck @@ -770,10 +770,9 @@ tls13_server_finished_send(struct tls13_ctx *ctx, CBB *cbb) { struct tls13_secrets *secrets = ctx->hs->secrets; struct tls13_secret context = { .data = "", .len = 0 }; - struct tls13_secret finished_key; + struct tls13_secret finished_key = { .data = NULL, .len = 0 } ; uint8_t transcript_hash[EVP_MAX_MD_SIZE]; size_t transcript_hash_len; - uint8_t key[EVP_MAX_MD_SIZE]; uint8_t *verify_data; size_t verify_data_len; unsigned int hlen; @@ -782,8 +781,8 @@ tls13_server_finished_send(struct tls13_ctx *ctx, CBB *cbb) SSL *s = ctx->ssl; int ret = 0; - finished_key.data = key; - finished_key.len = EVP_MD_size(ctx->hash); + if (!tls13_secret_init(&finished_key, EVP_MD_size(ctx->hash))) + goto err; if (!tls13_hkdf_expand_label(&finished_key, ctx->hash, &secrets->server_handshake_traffic, "finished", @@ -818,6 +817,7 @@ tls13_server_finished_send(struct tls13_ctx *ctx, CBB *cbb) ret = 1; err: + tls13_secret_cleanup(&finished_key); HMAC_CTX_free(hmac_ctx); return ret; -- cgit v1.2.3-55-g6feb