# HG changeset patch # User Maxim Dounin # Date 1665594893 -10800 # Node ID 0f3d98e4bcc57755ae8c2cd46a5f40096ad0a58c # Parent e13a271bdd400b518d857b968310e1aaabcebe90 SSL: automatic rotation of session ticket keys. As long as ssl_session_cache in shared memory is configured, session ticket keys are now automatically generated in shared memory, and rotated periodically. This can be beneficial from forward secrecy point of view, and also avoids increased CPU usage after configuration reloads. This also helps BoringSSL to properly resume sessions in configurations with multiple worker processes and no ssl_session_ticket_key directives, as BoringSSL tries to automatically rotate session ticket keys and does this independently in different worker processes, thus breaking session resumption between worker processes. diff --git a/src/event/ngx_event_openssl.c b/src/event/ngx_event_openssl.c --- a/src/event/ngx_event_openssl.c +++ b/src/event/ngx_event_openssl.c @@ -74,6 +74,7 @@ static void ngx_ssl_session_rbtree_inser static int ngx_ssl_ticket_key_callback(ngx_ssl_conn_t *ssl_conn, unsigned char *name, unsigned char *iv, EVP_CIPHER_CTX *ectx, HMAC_CTX *hctx, int enc); +static ngx_int_t ngx_ssl_rotate_ticket_keys(SSL_CTX *ssl_ctx, ngx_log_t *log); static void ngx_ssl_ticket_keys_cleanup(void *data); #endif @@ -3770,6 +3771,9 @@ ngx_ssl_session_cache_init(ngx_shm_zone_ ngx_queue_init(&cache->expire_queue); + cache->ticket_keys[0].expire = 0; + cache->ticket_keys[1].expire = 0; + cache->fail_time = 0; len = sizeof(" in SSL session shared cache \"\"") + shm_zone->shm.name.len; @@ -4240,11 +4244,13 @@ ngx_ssl_session_ticket_keys(ngx_conf_t * ngx_pool_cleanup_t *cln; ngx_ssl_ticket_key_t *key; - if (paths == NULL) { + if (paths == NULL + && SSL_CTX_get_ex_data(ssl->ctx, ngx_ssl_session_cache_index) == NULL) + { return NGX_OK; } - keys = ngx_array_create(cf->pool, paths->nelts, + keys = ngx_array_create(cf->pool, paths ? paths->nelts : 2, sizeof(ngx_ssl_ticket_key_t)); if (keys == NULL) { return NGX_ERROR; @@ -4258,6 +4264,34 @@ ngx_ssl_session_ticket_keys(ngx_conf_t * cln->handler = ngx_ssl_ticket_keys_cleanup; cln->data = keys; + if (SSL_CTX_set_ex_data(ssl->ctx, ngx_ssl_ticket_keys_index, keys) == 0) { + ngx_ssl_error(NGX_LOG_EMERG, ssl->log, 0, + "SSL_CTX_set_ex_data() failed"); + return NGX_ERROR; + } + + if (SSL_CTX_set_tlsext_ticket_key_cb(ssl->ctx, ngx_ssl_ticket_key_callback) + == 0) + { + ngx_log_error(NGX_LOG_WARN, cf->log, 0, + "nginx was built with Session Tickets support, however, " + "now it is linked dynamically to an OpenSSL library " + "which has no tlsext support, therefore Session Tickets " + "are not available"); + return NGX_OK; + } + + if (paths == NULL) { + + /* placeholder for keys in shared memory */ + + key = ngx_array_push_n(keys, 2); + key[0].shared = 1; + key[1].shared = 1; + + return NGX_OK; + } + path = paths->elts; for (i = 0; i < paths->nelts; i++) { @@ -4312,6 +4346,8 @@ ngx_ssl_session_ticket_keys(ngx_conf_t * goto failed; } + key->shared = 0; + if (size == 48) { key->size = 48; ngx_memcpy(key->name, buf, 16); @@ -4333,22 +4369,6 @@ ngx_ssl_session_ticket_keys(ngx_conf_t * ngx_explicit_memzero(&buf, 80); } - if (SSL_CTX_set_ex_data(ssl->ctx, ngx_ssl_ticket_keys_index, keys) == 0) { - ngx_ssl_error(NGX_LOG_EMERG, ssl->log, 0, - "SSL_CTX_set_ex_data() failed"); - return NGX_ERROR; - } - - if (SSL_CTX_set_tlsext_ticket_key_cb(ssl->ctx, ngx_ssl_ticket_key_callback) - == 0) - { - ngx_log_error(NGX_LOG_WARN, cf->log, 0, - "nginx was built with Session Tickets support, however, " - "now it is linked dynamically to an OpenSSL library " - "which has no tlsext support, therefore Session Tickets " - "are not available"); - } - return NGX_OK; failed: @@ -4381,6 +4401,10 @@ ngx_ssl_ticket_key_callback(ngx_ssl_conn c = ngx_ssl_get_connection(ssl_conn); ssl_ctx = c->ssl->session_ctx; + if (ngx_ssl_rotate_ticket_keys(ssl_ctx, c->log) != NGX_OK) { + return -1; + } + #ifdef OPENSSL_NO_SHA256 digest = EVP_sha1(); #else @@ -4499,6 +4523,113 @@ ngx_ssl_ticket_key_callback(ngx_ssl_conn } +static ngx_int_t +ngx_ssl_rotate_ticket_keys(SSL_CTX *ssl_ctx, ngx_log_t *log) +{ + time_t now, expire; + ngx_array_t *keys; + ngx_shm_zone_t *shm_zone; + ngx_slab_pool_t *shpool; + ngx_ssl_ticket_key_t *key; + ngx_ssl_session_cache_t *cache; + u_char buf[80]; + + keys = SSL_CTX_get_ex_data(ssl_ctx, ngx_ssl_ticket_keys_index); + if (keys == NULL) { + return NGX_OK; + } + + key = keys->elts; + + if (!key[0].shared) { + return NGX_OK; + } + + now = ngx_time(); + expire = now + SSL_CTX_get_timeout(ssl_ctx); + + shm_zone = SSL_CTX_get_ex_data(ssl_ctx, ngx_ssl_session_cache_index); + + cache = shm_zone->data; + shpool = (ngx_slab_pool_t *) shm_zone->shm.addr; + + ngx_shmtx_lock(&shpool->mutex); + + key = cache->ticket_keys; + + if (key[0].expire == 0) { + + /* initialize the current key */ + + if (RAND_bytes(buf, 80) != 1) { + ngx_ssl_error(NGX_LOG_ALERT, log, 0, "RAND_bytes() failed"); + ngx_shmtx_unlock(&shpool->mutex); + return NGX_ERROR; + } + + key->shared = 1; + key->expire = expire; + key->size = 80; + ngx_memcpy(key->name, buf, 16); + ngx_memcpy(key->hmac_key, buf + 16, 32); + ngx_memcpy(key->aes_key, buf + 48, 32); + + ngx_explicit_memzero(&buf, 80); + + ngx_log_debug2(NGX_LOG_DEBUG_EVENT, log, 0, + "ssl ticket key: \"%*xs\"", + (size_t) 16, key->name); + } + + if (key[1].expire < now) { + + /* + * if the previous key is no longer needed (or not initialized), + * replace it with the current key and generate new current key + */ + + key[1] = key[0]; + + if (RAND_bytes(buf, 80) != 1) { + ngx_ssl_error(NGX_LOG_ALERT, log, 0, "RAND_bytes() failed"); + ngx_shmtx_unlock(&shpool->mutex); + return NGX_ERROR; + } + + key->shared = 1; + key->expire = expire; + key->size = 80; + ngx_memcpy(key->name, buf, 16); + ngx_memcpy(key->hmac_key, buf + 16, 32); + ngx_memcpy(key->aes_key, buf + 48, 32); + + ngx_explicit_memzero(&buf, 80); + + ngx_log_debug2(NGX_LOG_DEBUG_EVENT, log, 0, + "ssl ticket key: \"%*xs\"", + (size_t) 16, key->name); + } + + /* + * update expiration of the current key: it is going to be needed + * at least till the session being created expires + */ + + if (expire > key[0].expire) { + key[0].expire = expire; + } + + /* sync keys to the worker process memory */ + + ngx_memcpy(keys->elts, cache->ticket_keys, + 2 * sizeof(ngx_ssl_ticket_key_t)); + + ngx_shmtx_unlock(&shpool->mutex); + + return NGX_OK; +} + + static void ngx_ssl_ticket_keys_cleanup(void *data) { diff --git a/src/event/ngx_event_openssl.h b/src/event/ngx_event_openssl.h --- a/src/event/ngx_event_openssl.h +++ b/src/event/ngx_event_openssl.h @@ -147,25 +147,24 @@ struct ngx_ssl_sess_id_s { typedef struct { + u_char name[16]; + u_char hmac_key[32]; + u_char aes_key[32]; + time_t expire; + unsigned size:8; + unsigned shared:1; +} ngx_ssl_ticket_key_t; + + +typedef struct { ngx_rbtree_t session_rbtree; ngx_rbtree_node_t sentinel; ngx_queue_t expire_queue; + ngx_ssl_ticket_key_t ticket_keys[2]; time_t fail_time; } ngx_ssl_session_cache_t; -#ifdef SSL_CTRL_SET_TLSEXT_TICKET_KEY_CB - -typedef struct { - size_t size; - u_char name[16]; - u_char hmac_key[32]; - u_char aes_key[32]; -} ngx_ssl_ticket_key_t; - -#endif - - #define NGX_SSL_SSLv2 0x0002 #define NGX_SSL_SSLv3 0x0004 #define NGX_SSL_TLSv1 0x0008