SSL: adjusted session id context with dynamic certificates.
Dynamic certificates re-introduce problem with incorrect session
reuse (AKA "virtual host confusion", CVE-2014-3616), since there are
no server certificates to generate session id context from.
To prevent this, session id context is now generated from ssl_certificate
directives as specified in the configuration. This approach prevents
incorrect session reuse in most cases, while still allowing sharing
sessions across multiple machines with ssl_session_ticket_key set as
long as configurations are identical.
diff --git a/src/event/ngx_event_openssl.c b/src/event/ngx_event_openssl.c
index c6eb65c..e18778e 100644
--- a/src/event/ngx_event_openssl.c
+++ b/src/event/ngx_event_openssl.c
@@ -54,7 +54,7 @@
static void ngx_ssl_clear_error(ngx_log_t *log);
static ngx_int_t ngx_ssl_session_id_context(ngx_ssl_t *ssl,
- ngx_str_t *sess_ctx);
+ ngx_str_t *sess_ctx, ngx_array_t *certificates);
static int ngx_ssl_new_session(ngx_ssl_conn_t *ssl_conn,
ngx_ssl_session_t *sess);
static ngx_ssl_session_t *ngx_ssl_get_cached_session(ngx_ssl_conn_t *ssl_conn,
@@ -3013,13 +3013,14 @@
ngx_int_t
ngx_ssl_session_cache(ngx_ssl_t *ssl, ngx_str_t *sess_ctx,
- ssize_t builtin_session_cache, ngx_shm_zone_t *shm_zone, time_t timeout)
+ ngx_array_t *certificates, ssize_t builtin_session_cache,
+ ngx_shm_zone_t *shm_zone, time_t timeout)
{
long cache_mode;
SSL_CTX_set_timeout(ssl->ctx, (long) timeout);
- if (ngx_ssl_session_id_context(ssl, sess_ctx) != NGX_OK) {
+ if (ngx_ssl_session_id_context(ssl, sess_ctx, certificates) != NGX_OK) {
return NGX_ERROR;
}
@@ -3085,11 +3086,14 @@
static ngx_int_t
-ngx_ssl_session_id_context(ngx_ssl_t *ssl, ngx_str_t *sess_ctx)
+ngx_ssl_session_id_context(ngx_ssl_t *ssl, ngx_str_t *sess_ctx,
+ ngx_array_t *certificates)
{
int n, i;
X509 *cert;
X509_NAME *name;
+ ngx_str_t *certs;
+ ngx_uint_t k;
EVP_MD_CTX *md;
unsigned int len;
STACK_OF(X509_NAME) *list;
@@ -3134,6 +3138,24 @@
}
}
+ if (SSL_CTX_get_ex_data(ssl->ctx, ngx_ssl_certificate_index) == NULL) {
+
+ /*
+ * If certificates are loaded dynamically, we use certificate
+ * names as specified in the configuration (with variables).
+ */
+
+ certs = certificates->elts;
+ for (k = 0; k < certificates->nelts; k++) {
+
+ if (EVP_DigestUpdate(md, certs[k].data, certs[k].len) == 0) {
+ ngx_ssl_error(NGX_LOG_EMERG, ssl->log, 0,
+ "EVP_DigestUpdate() failed");
+ goto failed;
+ }
+ }
+ }
+
list = SSL_CTX_get_client_CA_list(ssl->ctx);
if (list != NULL) {
diff --git a/src/event/ngx_event_openssl.h b/src/event/ngx_event_openssl.h
index 21ed19e..61da0c5 100644
--- a/src/event/ngx_event_openssl.h
+++ b/src/event/ngx_event_openssl.h
@@ -192,7 +192,8 @@
ngx_int_t ngx_ssl_client_session_cache(ngx_conf_t *cf, ngx_ssl_t *ssl,
ngx_uint_t enable);
ngx_int_t ngx_ssl_session_cache(ngx_ssl_t *ssl, ngx_str_t *sess_ctx,
- ssize_t builtin_session_cache, ngx_shm_zone_t *shm_zone, time_t timeout);
+ ngx_array_t *certificates, ssize_t builtin_session_cache,
+ ngx_shm_zone_t *shm_zone, time_t timeout);
ngx_int_t ngx_ssl_session_ticket_keys(ngx_conf_t *cf, ngx_ssl_t *ssl,
ngx_array_t *paths);
ngx_int_t ngx_ssl_session_cache_init(ngx_shm_zone_t *shm_zone, void *data);
diff --git a/src/http/modules/ngx_http_ssl_module.c b/src/http/modules/ngx_http_ssl_module.c
index 3134f0e..3bf122a 100644
--- a/src/http/modules/ngx_http_ssl_module.c
+++ b/src/http/modules/ngx_http_ssl_module.c
@@ -817,7 +817,7 @@
}
if (ngx_ssl_session_cache(&conf->ssl, &ngx_http_ssl_sess_id_ctx,
- conf->builtin_session_cache,
+ conf->certificates, conf->builtin_session_cache,
conf->shm_zone, conf->session_timeout)
!= NGX_OK)
{
diff --git a/src/mail/ngx_mail_ssl_module.c b/src/mail/ngx_mail_ssl_module.c
index 4509597..10e982e 100644
--- a/src/mail/ngx_mail_ssl_module.c
+++ b/src/mail/ngx_mail_ssl_module.c
@@ -435,7 +435,7 @@
}
if (ngx_ssl_session_cache(&conf->ssl, &ngx_mail_ssl_sess_id_ctx,
- conf->builtin_session_cache,
+ conf->certificates, conf->builtin_session_cache,
conf->shm_zone, conf->session_timeout)
!= NGX_OK)
{
diff --git a/src/stream/ngx_stream_ssl_module.c b/src/stream/ngx_stream_ssl_module.c
index 7e91d5b..9ab2c82 100644
--- a/src/stream/ngx_stream_ssl_module.c
+++ b/src/stream/ngx_stream_ssl_module.c
@@ -766,7 +766,7 @@
}
if (ngx_ssl_session_cache(&conf->ssl, &ngx_stream_ssl_sess_id_ctx,
- conf->builtin_session_cache,
+ conf->certificates, conf->builtin_session_cache,
conf->shm_zone, conf->session_timeout)
!= NGX_OK)
{
