From c2d3d82ccbea18f0504fbaceeee6efb62da8d1d8 Mon Sep 17 00:00:00 2001 From: Maxim Dounin Date: Fri, 23 Dec 2016 17:28:20 +0300 Subject: [PATCH] SSL: support AES256 encryption of tickets. This implies ticket key size of 80 bytes instead of previously used 48, as both HMAC and AES keys are 32 bytes now. When an old 48-byte ticket key is provided, we fall back to using backward-compatible AES128 encryption. OpenSSL switched to using AES256 in 1.1.0, and we are providing equivalent security. While here, order of HMAC and AES keys was reverted to make the implementation compatible with keys used by OpenSSL with SSL_CTX_set_tlsext_ticket_keys(). Prodded by Christian Klinger. --- src/event/ngx_event_openssl.c | 58 ++++++++++++++++++++++++++--------- src/event/ngx_event_openssl.h | 5 +-- 2 files changed, 47 insertions(+), 16 deletions(-) diff --git a/src/event/ngx_event_openssl.c b/src/event/ngx_event_openssl.c index c98e3c2b0..3c74b7b21 100644 --- a/src/event/ngx_event_openssl.c +++ b/src/event/ngx_event_openssl.c @@ -2856,7 +2856,8 @@ ngx_ssl_session_rbtree_insert_value(ngx_rbtree_node_t *temp, ngx_int_t ngx_ssl_session_ticket_keys(ngx_conf_t *cf, ngx_ssl_t *ssl, ngx_array_t *paths) { - u_char buf[48]; + u_char buf[80]; + size_t size; ssize_t n; ngx_str_t *path; ngx_file_t file; @@ -2899,13 +2900,15 @@ ngx_ssl_session_ticket_keys(ngx_conf_t *cf, ngx_ssl_t *ssl, ngx_array_t *paths) goto failed; } - if (ngx_file_size(&fi) != 48) { + size = ngx_file_size(&fi); + + if (size != 48 && size != 80) { ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, - "\"%V\" must be 48 bytes", &file.name); + "\"%V\" must be 48 or 80 bytes", &file.name); goto failed; } - n = ngx_read_file(&file, buf, 48, 0); + n = ngx_read_file(&file, buf, size, 0); if (n == NGX_ERROR) { ngx_conf_log_error(NGX_LOG_CRIT, cf, ngx_errno, @@ -2913,10 +2916,10 @@ ngx_ssl_session_ticket_keys(ngx_conf_t *cf, ngx_ssl_t *ssl, ngx_array_t *paths) goto failed; } - if (n != 48) { + if ((size_t) n != size) { ngx_conf_log_error(NGX_LOG_CRIT, cf, 0, ngx_read_file_n " \"%V\" returned only " - "%z bytes instead of 48", &file.name, n); + "%z bytes instead of %uz", &file.name, n, size); goto failed; } @@ -2925,9 +2928,18 @@ ngx_ssl_session_ticket_keys(ngx_conf_t *cf, ngx_ssl_t *ssl, ngx_array_t *paths) goto failed; } - ngx_memcpy(key->name, buf, 16); - ngx_memcpy(key->aes_key, buf + 16, 16); - ngx_memcpy(key->hmac_key, buf + 32, 16); + if (size == 48) { + key->size = 48; + ngx_memcpy(key->name, buf, 16); + ngx_memcpy(key->aes_key, buf + 16, 16); + ngx_memcpy(key->hmac_key, buf + 32, 16); + + } else { + 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); + } if (ngx_close_file(file.fd) == NGX_FILE_ERROR) { ngx_log_error(NGX_LOG_ALERT, cf->log, ngx_errno, @@ -2972,6 +2984,7 @@ ngx_ssl_session_ticket_key_callback(ngx_ssl_conn_t *ssl_conn, unsigned char *name, unsigned char *iv, EVP_CIPHER_CTX *ectx, HMAC_CTX *hctx, int enc) { + size_t size; SSL_CTX *ssl_ctx; ngx_uint_t i; ngx_array_t *keys; @@ -2986,7 +2999,6 @@ ngx_ssl_session_ticket_key_callback(ngx_ssl_conn_t *ssl_conn, c = ngx_ssl_get_connection(ssl_conn); ssl_ctx = c->ssl->session_ctx; - cipher = EVP_aes_128_cbc(); #ifdef OPENSSL_NO_SHA256 digest = EVP_sha1(); #else @@ -3008,6 +3020,15 @@ ngx_ssl_session_ticket_key_callback(ngx_ssl_conn_t *ssl_conn, ngx_hex_dump(buf, key[0].name, 16) - buf, buf, SSL_session_reused(ssl_conn) ? "reused" : "new"); + if (key[0].size == 48) { + cipher = EVP_aes_128_cbc(); + size = 16; + + } else { + cipher = EVP_aes_256_cbc(); + size = 32; + } + if (RAND_bytes(iv, EVP_CIPHER_iv_length(cipher)) != 1) { ngx_ssl_error(NGX_LOG_ALERT, c->log, 0, "RAND_bytes() failed"); return -1; @@ -3020,12 +3041,12 @@ ngx_ssl_session_ticket_key_callback(ngx_ssl_conn_t *ssl_conn, } #if OPENSSL_VERSION_NUMBER >= 0x10000000L - if (HMAC_Init_ex(hctx, key[0].hmac_key, 16, digest, NULL) != 1) { + if (HMAC_Init_ex(hctx, key[0].hmac_key, size, digest, NULL) != 1) { ngx_ssl_error(NGX_LOG_ALERT, c->log, 0, "HMAC_Init_ex() failed"); return -1; } #else - HMAC_Init_ex(hctx, key[0].hmac_key, 16, digest, NULL); + HMAC_Init_ex(hctx, key[0].hmac_key, size, digest, NULL); #endif ngx_memcpy(name, key[0].name, 16); @@ -3054,13 +3075,22 @@ ngx_ssl_session_ticket_key_callback(ngx_ssl_conn_t *ssl_conn, ngx_hex_dump(buf, key[i].name, 16) - buf, buf, (i == 0) ? " (default)" : ""); + if (key[i].size == 48) { + cipher = EVP_aes_128_cbc(); + size = 16; + + } else { + cipher = EVP_aes_256_cbc(); + size = 32; + } + #if OPENSSL_VERSION_NUMBER >= 0x10000000L - if (HMAC_Init_ex(hctx, key[i].hmac_key, 16, digest, NULL) != 1) { + if (HMAC_Init_ex(hctx, key[i].hmac_key, size, digest, NULL) != 1) { ngx_ssl_error(NGX_LOG_ALERT, c->log, 0, "HMAC_Init_ex() failed"); return -1; } #else - HMAC_Init_ex(hctx, key[i].hmac_key, 16, digest, NULL); + HMAC_Init_ex(hctx, key[i].hmac_key, size, digest, NULL); #endif if (EVP_DecryptInit_ex(ectx, cipher, NULL, key[i].aes_key, iv) != 1) { diff --git a/src/event/ngx_event_openssl.h b/src/event/ngx_event_openssl.h index c0223070c..e093e10c5 100644 --- a/src/event/ngx_event_openssl.h +++ b/src/event/ngx_event_openssl.h @@ -117,9 +117,10 @@ typedef struct { #ifdef SSL_CTRL_SET_TLSEXT_TICKET_KEY_CB typedef struct { + size_t size; u_char name[16]; - u_char aes_key[16]; - u_char hmac_key[16]; + u_char hmac_key[32]; + u_char aes_key[32]; } ngx_ssl_session_ticket_key_t; #endif