From 651b949d85f847318ece301b64c099ad7959e9d0 Mon Sep 17 00:00:00 2001 From: Sverker Eriksson Date: Wed, 12 Feb 2014 15:05:52 +0100 Subject: crypto: Fix bug when using old hmac context Symptom: Using an old context (that had already been passed as argument to either hmac_upgrade or hmac_final) could cause VM crash or worse. Reason: Only a shallow copy (memcpy) of the context was made causing a new context to partly mutate its parent context into an inconsistent state. Problem: Only OpenSSL v1.0 supports deep copy of hmac context. It is thus not possible to implement a functional interface for older OpenSSL versions (0.9.8) which still have wide spread use. Solution: Change hmac contexts into a mutable state using NIF resources. Document reuse of old contexts as undefined. Future: If a need for reusing old context variables arise, a new hmac_copy function could be introduced that is only supported for OpenSSL v1.0. --- lib/crypto/c_src/crypto.c | 87 ++++++++++++++++++++++++++++--------------- lib/crypto/doc/src/crypto.xml | 8 +++- 2 files changed, 64 insertions(+), 31 deletions(-) (limited to 'lib/crypto') diff --git a/lib/crypto/c_src/crypto.c b/lib/crypto/c_src/crypto.c index 925ad0c091..2e1a21178f 100644 --- a/lib/crypto/c_src/crypto.c +++ b/lib/crypto/c_src/crypto.c @@ -1,7 +1,7 @@ /* * %CopyrightBegin% * - * Copyright Ericsson AB 2010-2013. All Rights Reserved. + * Copyright Ericsson AB 2010-2014. All Rights Reserved. * * The contents of this file are subject to the Erlang Public License, * Version 1.1, (the "License"); you may not use this file except in @@ -444,6 +444,15 @@ static ERL_NIF_TERM atom_ppbasis; static ERL_NIF_TERM atom_onbasis; #endif +static ErlNifResourceType* hmac_context_rtype; +struct hmac_context +{ + ErlNifMutex* mtx; + int alive; + HMAC_CTX ctx; +}; +static void hmac_context_dtor(ErlNifEnv* env, struct hmac_context*); + /* #define PRINTF_ERR0(FMT) enif_fprintf(stderr, FMT "\n") #define PRINTF_ERR1(FMT, A1) enif_fprintf(stderr, FMT "\n", A1) @@ -498,6 +507,15 @@ static int init(ErlNifEnv* env, ERL_NIF_TERM load_info) return 0; } + hmac_context_rtype = enif_open_resource_type(env, NULL, "hmac_context", + (ErlNifResourceDtor*) hmac_context_dtor, + ERL_NIF_RT_CREATE|ERL_NIF_RT_TAKEOVER, + NULL); + if (!hmac_context_rtype) { + PRINTF_ERR0("CRYPTO: Could not open resource type 'hmac_context'"); + return 0; + } + if (library_refc > 0) { /* Repeated loading of this library (module upgrade). * Atoms and callbacks are already set, we are done. @@ -1280,11 +1298,19 @@ static ERL_NIF_TERM sha512_mac_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM #endif } +static void hmac_context_dtor(ErlNifEnv* env, struct hmac_context *obj) +{ + if (obj->alive) { + HMAC_CTX_cleanup(&obj->ctx); + obj->alive = 0; + } + enif_mutex_destroy(obj->mtx); +} + static ERL_NIF_TERM hmac_init(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[]) {/* (Type, Key) */ ErlNifBinary key; - ERL_NIF_TERM ret; - unsigned char * ctx_buf; + struct hmac_context* obj; const EVP_MD *md; if (argv[0] == atom_sha) md = EVP_sha1(); @@ -1309,57 +1335,60 @@ static ERL_NIF_TERM hmac_init(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[ return enif_make_badarg(env); } - ctx_buf = enif_make_new_binary(env, sizeof(HMAC_CTX), &ret); - HMAC_CTX_init((HMAC_CTX *) ctx_buf); - HMAC_Init((HMAC_CTX *) ctx_buf, key.data, key.size, md); + obj = enif_alloc_resource(hmac_context_rtype, sizeof(struct hmac_context)); + obj->mtx = enif_mutex_create("crypto.hmac"); + obj->alive = 1; + HMAC_CTX_init(&obj->ctx); + HMAC_Init(&obj->ctx, key.data, key.size, md); - return ret; + return enif_make_resource(env, obj); } static ERL_NIF_TERM hmac_update(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[]) {/* (Context, Data) */ - ErlNifBinary context, data; - ERL_NIF_TERM ret; - unsigned char * ctx_buf; + ErlNifBinary data; + struct hmac_context* obj; - if (!enif_inspect_binary(env, argv[0], &context) - || !enif_inspect_iolist_as_binary(env, argv[1], &data) - || context.size != sizeof(HMAC_CTX)) { + if (!enif_get_resource(env, argv[0], hmac_context_rtype, (void**)&obj) + || !enif_inspect_iolist_as_binary(env, argv[1], &data)) { + return enif_make_badarg(env); + } + enif_mutex_lock(obj->mtx); + if (!obj->alive) { + enif_mutex_unlock(obj->mtx); return enif_make_badarg(env); } + HMAC_Update(&obj->ctx, data.data, data.size); + enif_mutex_unlock(obj->mtx); - ctx_buf = enif_make_new_binary(env, sizeof(HMAC_CTX), &ret); - memcpy(ctx_buf, context.data, context.size); - HMAC_Update((HMAC_CTX *)ctx_buf, data.data, data.size); CONSUME_REDS(env,data); - - return ret; + return argv[0]; } static ERL_NIF_TERM hmac_final(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[]) {/* (Context) or (Context, HashLen) */ - ErlNifBinary context; ERL_NIF_TERM ret; - HMAC_CTX ctx; + struct hmac_context* obj; unsigned char mac_buf[EVP_MAX_MD_SIZE]; unsigned char * mac_bin; unsigned int req_len = 0; unsigned int mac_len; - if (!enif_inspect_binary(env, argv[0], &context)) { - return enif_make_badarg(env); - } - if (argc == 2 && !enif_get_uint(env, argv[1], &req_len)) { + if (!enif_get_resource(env,argv[0],hmac_context_rtype, (void**)&obj) + || (argc == 2 && !enif_get_uint(env, argv[1], &req_len))) { return enif_make_badarg(env); } - if (context.size != sizeof(ctx)) { - return enif_make_badarg(env); + enif_mutex_lock(obj->mtx); + if (!obj->alive) { + enif_mutex_unlock(obj->mtx); + return enif_make_badarg(env); } - memcpy(&ctx, context.data, context.size); - HMAC_Final(&ctx, mac_buf, &mac_len); - HMAC_CTX_cleanup(&ctx); + HMAC_Final(&obj->ctx, mac_buf, &mac_len); + HMAC_CTX_cleanup(&obj->ctx); + obj->alive = 0; + enif_mutex_unlock(obj->mtx); if (argc == 2 && req_len < mac_len) { /* Only truncate to req_len bytes if asked. */ diff --git a/lib/crypto/doc/src/crypto.xml b/lib/crypto/doc/src/crypto.xml index 40f829e704..c95827c371 100644 --- a/lib/crypto/doc/src/crypto.xml +++ b/lib/crypto/doc/src/crypto.xml @@ -4,7 +4,7 @@
- 19992013 + 19992014 Ericsson AB. All Rights Reserved. @@ -366,7 +366,11 @@ or to one of the functions hmac_final and hmac_final_n

- +

Do not use a Context as argument in more than one + call to hmac_update or hmac_final. The semantics of reusing old contexts + in any way is undefined and could even crash the VM in earlier releases. + The reason for this limitation is a lack of support in the underlying + OpenSSL API.

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