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openssl: Avoid use-after-free when rehashing fails to load new files

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Commit 5c8da48 introduced a fix for issue #186 by freeing the old SSL_CTX
structure before constructing a new one, which could disconnect existing
clients otherwise.

Unfortunately, the freeing is done first, which means that if setting up
a new structure fails for any reason, there will be no usable structures
left, but they are still referenced.

This fix moves the freeing to the end of the function, using intermediate
new variables in the meantime. This problem was discovered while testing
against OpenSSL 1.1.0 RC6.
This commit is contained in:
Aaron Jones 2016-08-12 13:15:56 +00:00
parent 419f0c6af7
commit 0bd2f0b710
No known key found for this signature in database
GPG key ID: EC6F86EE9CD840B5
1 changed files with 43 additions and 30 deletions
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73
libratbox/src/openssl.c
View file

@ -376,6 +376,9 @@ rb_setup_ssl_server(const char *cert, const char *keyfile, const char *dhfile, c
{ {
const char libratbox_ciphers[] = "kEECDH+HIGH:kEDH+HIGH:HIGH:!aNULL"; const char libratbox_ciphers[] = "kEECDH+HIGH:kEDH+HIGH:HIGH:!aNULL";
SSL_CTX *ssl_server_ctx_new;
SSL_CTX *ssl_client_ctx_new;
#ifdef LRB_HAVE_TLS_SET_CURVES #ifdef LRB_HAVE_TLS_SET_CURVES
const char libratbox_curves[] = "P-521:P-384:P-256"; const char libratbox_curves[] = "P-521:P-384:P-256";
#endif #endif
@ -395,67 +398,62 @@ rb_setup_ssl_server(const char *cert, const char *keyfile, const char *dhfile, c
if(cipher_list == NULL) if(cipher_list == NULL)
cipher_list = libratbox_ciphers; cipher_list = libratbox_ciphers;
if(ssl_server_ctx)
SSL_CTX_free(ssl_server_ctx);
if(ssl_client_ctx)
SSL_CTX_free(ssl_client_ctx);
#ifdef LRB_HAVE_TLS_METHOD_API #ifdef LRB_HAVE_TLS_METHOD_API
ssl_server_ctx = SSL_CTX_new(TLS_server_method()); ssl_server_ctx_new = SSL_CTX_new(TLS_server_method());
ssl_client_ctx = SSL_CTX_new(TLS_client_method()); ssl_client_ctx_new = SSL_CTX_new(TLS_client_method());
#else #else
ssl_server_ctx = SSL_CTX_new(SSLv23_server_method()); ssl_server_ctx_new = SSL_CTX_new(SSLv23_server_method());
ssl_client_ctx = SSL_CTX_new(SSLv23_client_method()); ssl_client_ctx_new = SSL_CTX_new(SSLv23_client_method());
#endif #endif
if(ssl_server_ctx == NULL) if(ssl_server_ctx_new == NULL)
{ {
rb_lib_log("rb_init_openssl: Unable to initialize OpenSSL server context: %s", rb_lib_log("rb_init_openssl: Unable to initialize OpenSSL server context: %s",
get_ssl_error(ERR_get_error())); get_ssl_error(ERR_get_error()));
return 0; return 0;
} }
if(ssl_client_ctx == NULL) if(ssl_client_ctx_new == NULL)
{ {
rb_lib_log("rb_init_openssl: Unable to initialize OpenSSL client context: %s", rb_lib_log("rb_init_openssl: Unable to initialize OpenSSL client context: %s",
get_ssl_error(ERR_get_error())); get_ssl_error(ERR_get_error()));
SSL_CTX_free(ssl_server_ctx_new);
return 0; return 0;
} }
#ifndef LRB_HAVE_TLS_METHOD_API #ifndef LRB_HAVE_TLS_METHOD_API
SSL_CTX_set_options(ssl_server_ctx, SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3); SSL_CTX_set_options(ssl_server_ctx_new, SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3);
SSL_CTX_set_options(ssl_client_ctx, SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3); SSL_CTX_set_options(ssl_client_ctx_new, SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3);
#endif #endif
#ifdef SSL_OP_SINGLE_DH_USE #ifdef SSL_OP_SINGLE_DH_USE
SSL_CTX_set_options(ssl_server_ctx, SSL_OP_SINGLE_DH_USE); SSL_CTX_set_options(ssl_server_ctx_new, SSL_OP_SINGLE_DH_USE);
#endif #endif
#ifdef SSL_OP_SINGLE_ECDH_USE #ifdef SSL_OP_SINGLE_ECDH_USE
SSL_CTX_set_options(ssl_server_ctx, SSL_OP_SINGLE_ECDH_USE); SSL_CTX_set_options(ssl_server_ctx_new, SSL_OP_SINGLE_ECDH_USE);
#endif #endif
#ifdef SSL_OP_NO_TICKET #ifdef SSL_OP_NO_TICKET
SSL_CTX_set_options(ssl_server_ctx, SSL_OP_NO_TICKET); SSL_CTX_set_options(ssl_server_ctx_new, SSL_OP_NO_TICKET);
SSL_CTX_set_options(ssl_client_ctx, SSL_OP_NO_TICKET); SSL_CTX_set_options(ssl_client_ctx_new, SSL_OP_NO_TICKET);
#endif #endif
#ifdef SSL_OP_CIPHER_SERVER_PREFERENCE #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
SSL_CTX_set_options(ssl_server_ctx, SSL_OP_CIPHER_SERVER_PREFERENCE); SSL_CTX_set_options(ssl_server_ctx_new, SSL_OP_CIPHER_SERVER_PREFERENCE);
#endif #endif
#ifdef LRB_HAVE_TLS_ECDH_AUTO #ifdef LRB_HAVE_TLS_ECDH_AUTO
SSL_CTX_set_ecdh_auto(ssl_server_ctx, 1); SSL_CTX_set_ecdh_auto(ssl_server_ctx_new, 1);
#endif #endif
#ifdef LRB_HAVE_TLS_SET_CURVES #ifdef LRB_HAVE_TLS_SET_CURVES
SSL_CTX_set1_curves_list(ssl_server_ctx, libratbox_curves); SSL_CTX_set1_curves_list(ssl_server_ctx_new, libratbox_curves);
SSL_CTX_set1_curves_list(ssl_client_ctx, libratbox_curves); SSL_CTX_set1_curves_list(ssl_client_ctx_new, libratbox_curves);
#endif #endif
SSL_CTX_set_verify(ssl_server_ctx, SSL_VERIFY_PEER | SSL_VERIFY_CLIENT_ONCE, verify_accept_all_cb); SSL_CTX_set_verify(ssl_server_ctx_new, SSL_VERIFY_PEER | SSL_VERIFY_CLIENT_ONCE, verify_accept_all_cb);
SSL_CTX_set_session_cache_mode(ssl_server_ctx, SSL_SESS_CACHE_OFF); SSL_CTX_set_session_cache_mode(ssl_server_ctx_new, SSL_SESS_CACHE_OFF);
/* /*
* Set manual ECDHE curve on OpenSSL 1.0.0 & 1.0.1, but make sure it's actually available * Set manual ECDHE curve on OpenSSL 1.0.0 & 1.0.1, but make sure it's actually available
@ -463,25 +461,31 @@ rb_setup_ssl_server(const char *cert, const char *keyfile, const char *dhfile, c
#if (OPENSSL_VERSION_NUMBER >= 0x10000000L) && (OPENSSL_VERSION_NUMBER < 0x10002000L) && !defined(OPENSSL_NO_ECDH) #if (OPENSSL_VERSION_NUMBER >= 0x10000000L) && (OPENSSL_VERSION_NUMBER < 0x10002000L) && !defined(OPENSSL_NO_ECDH)
EC_KEY *key = EC_KEY_new_by_curve_name(NID_secp384r1); EC_KEY *key = EC_KEY_new_by_curve_name(NID_secp384r1);
if(key) { if(key) {
SSL_CTX_set_tmp_ecdh(ssl_server_ctx, key); SSL_CTX_set_tmp_ecdh(ssl_server_ctx_new, key);
EC_KEY_free(key); EC_KEY_free(key);
} }
#endif #endif
SSL_CTX_set_cipher_list(ssl_server_ctx, cipher_list); SSL_CTX_set_cipher_list(ssl_server_ctx_new, cipher_list);
SSL_CTX_set_cipher_list(ssl_client_ctx, cipher_list); SSL_CTX_set_cipher_list(ssl_client_ctx_new, cipher_list);
if(!SSL_CTX_use_certificate_chain_file(ssl_server_ctx, cert) || !SSL_CTX_use_certificate_chain_file(ssl_client_ctx, cert)) if(!SSL_CTX_use_certificate_chain_file(ssl_server_ctx_new, cert) || !SSL_CTX_use_certificate_chain_file(ssl_client_ctx_new, cert))
{ {
rb_lib_log("rb_setup_ssl_server: Error loading certificate file [%s]: %s", cert, rb_lib_log("rb_setup_ssl_server: Error loading certificate file [%s]: %s", cert,
get_ssl_error(ERR_get_error())); get_ssl_error(ERR_get_error()));
SSL_CTX_free(ssl_server_ctx_new);
SSL_CTX_free(ssl_client_ctx_new);
return 0; return 0;
} }
if(!SSL_CTX_use_PrivateKey_file(ssl_server_ctx, keyfile, SSL_FILETYPE_PEM) || !SSL_CTX_use_PrivateKey_file(ssl_client_ctx, keyfile, SSL_FILETYPE_PEM)) if(!SSL_CTX_use_PrivateKey_file(ssl_server_ctx_new, keyfile, SSL_FILETYPE_PEM) || !SSL_CTX_use_PrivateKey_file(ssl_client_ctx_new, keyfile, SSL_FILETYPE_PEM))
{ {
rb_lib_log("rb_setup_ssl_server: Error loading keyfile [%s]: %s", keyfile, rb_lib_log("rb_setup_ssl_server: Error loading keyfile [%s]: %s", keyfile,
get_ssl_error(ERR_get_error())); get_ssl_error(ERR_get_error()));
SSL_CTX_free(ssl_server_ctx_new);
SSL_CTX_free(ssl_client_ctx_new);
return 0; return 0;
} }
@ -504,12 +508,21 @@ rb_setup_ssl_server(const char *cert, const char *keyfile, const char *dhfile, c
} }
else else
{ {
SSL_CTX_set_tmp_dh(ssl_server_ctx, dh); SSL_CTX_set_tmp_dh(ssl_server_ctx_new, dh);
DH_free(dh); DH_free(dh);
fclose(fp); fclose(fp);
} }
} }
if(ssl_server_ctx)
SSL_CTX_free(ssl_server_ctx);
if(ssl_client_ctx)
SSL_CTX_free(ssl_client_ctx);
ssl_server_ctx = ssl_server_ctx_new;
ssl_client_ctx = ssl_client_ctx_new;
return 1; return 1;
} }