* Exim - an Internet mail transport agent *
*************************************************/
-/* Copyright (c) University of Cambridge 1995 - 2018 */
+/* Copyright (c) University of Cambridge 1995 - 2019 */
/* See the file NOTICE for conditions of use and distribution. */
/* Portions Copyright (c) The OpenSSL Project 1999 */
# define EXIM_HAVE_OPENSSL_TLS_METHOD
# define EXIM_HAVE_OPENSSL_KEYLOG
# define EXIM_HAVE_OPENSSL_CIPHER_GET_ID
+# define EXIM_HAVE_SESSION_TICKET
# else
# define EXIM_NEED_OPENSSL_INIT
# endif
spf(buf, sizeof(buf), US"_OPT_OPENSSL_%T_X", o->name);
builtin_macro_create(buf);
}
+
+# ifdef EXPERIMENTAL_TLS_RESUME
+builtin_macro_create_var(US"_RESUME_DECODE", RESUME_DECODE_STRING );
+# endif
}
#else
static char ssl_errstring[256];
-static int ssl_session_timeout = 200;
+static int ssl_session_timeout = 3600;
static BOOL client_verify_optional = FALSE;
static BOOL server_verify_optional = FALSE;
typedef struct tls_ext_ctx_cb {
+ tls_support * tlsp;
uschar *certificate;
uschar *privatekey;
BOOL is_server;
/* should figure out a cleanup of API to handle state preserved per
implementation, for various reasons, which can be void * in the APIs.
For now, we hack around it. */
-tls_ext_ctx_cb *client_static_cbinfo = NULL;
+tls_ext_ctx_cb *client_static_cbinfo = NULL; /*XXX should not use static; multiple concurrent clients! */
tls_ext_ctx_cb *server_static_cbinfo = NULL;
static int
#endif
+
+/* Daemon-called key create/rotate */
+#ifdef EXPERIMENTAL_TLS_RESUME
+static void tk_init(void);
+static int tls_exdata_idx = -1;
+#endif
+
+void
+tls_daemon_init(void)
+{
+#ifdef EXPERIMENTAL_TLS_RESUME
+tk_init();
+#endif
+return;
+}
+
+
/*************************************************
* Handle TLS error *
*************************************************/
#endif
+#ifdef EXPERIMENTAL_TLS_RESUME
+/* Manage the keysets used for encrypting the session tickets, on the server. */
+
+typedef struct { /* Session ticket encryption key */
+ uschar name[16];
+
+ const EVP_CIPHER * aes_cipher;
+ uschar aes_key[16]; /* size needed depends on cipher. aes_128 implies 128/8 = 16? */
+ const EVP_MD * hmac_hash;
+ uschar hmac_key[16];
+ time_t renew;
+ time_t expire;
+} exim_stek;
+
+/*XXX for now just always create/find the one key.
+Worry about rotation and overlap later. */
+
+static exim_stek exim_tk;
+static exim_stek exim_tk_old;
+
+static void
+tk_init(void)
+{
+if (exim_tk.name[0])
+ {
+ if (exim_tk.renew >= time(NULL)) return;
+ exim_tk_old = exim_tk;
+ }
+
+if (f.running_in_test_harness) ssl_session_timeout = 6;
+
+DEBUG(D_tls) debug_printf("OpenSSL: %s STEK\n", exim_tk.name[0] ? "rotating" : "creating");
+if (RAND_bytes(exim_tk.aes_key, sizeof(exim_tk.aes_key)) <= 0) return;
+if (RAND_bytes(exim_tk.hmac_key, sizeof(exim_tk.hmac_key)) <= 0) return;
+if (RAND_bytes(exim_tk.name+1, sizeof(exim_tk.name)-1) <= 0) return;
+
+exim_tk.name[0] = 'E';
+exim_tk.aes_cipher = EVP_aes_128_cbc();
+exim_tk.hmac_hash = EVP_sha256();
+exim_tk.expire = time(NULL) + ssl_session_timeout;
+exim_tk.renew = exim_tk.expire - ssl_session_timeout/2;
+}
+
+static exim_stek *
+tk_current(void)
+{
+if (!exim_tk.name[0]) return NULL;
+return &exim_tk;
+}
+
+static exim_stek *
+tk_find(const uschar * name)
+{
+return memcmp(name, exim_tk.name, sizeof(exim_tk.name)) == 0 ? &exim_tk
+ : memcmp(name, exim_tk_old.name, sizeof(exim_tk_old.name)) == 0 ? &exim_tk_old
+ : NULL;
+}
+
+/* Callback for session tickets, on server */
+static int
+ticket_key_callback(SSL * ssl, uschar key_name[16],
+ uschar * iv, EVP_CIPHER_CTX * ctx, HMAC_CTX * hctx, int enc)
+{
+tls_support * tlsp = server_static_cbinfo->tlsp;
+exim_stek * key;
+
+if (enc)
+ {
+ DEBUG(D_tls) debug_printf("ticket_key_callback: create new session\n");
+ tlsp->resumption |= RESUME_CLIENT_REQUESTED;
+
+ if (RAND_bytes(iv, EVP_MAX_IV_LENGTH) <= 0)
+ return -1; /* insufficient random */
+
+ if (!(key = tk_current())) /* current key doesn't exist or isn't valid */
+ return 0; /* key couldn't be created */
+ memcpy(key_name, key->name, 16);
+ DEBUG(D_tls) debug_printf("STEK expire %ld\n", key->expire - time(NULL));
+
+ /*XXX will want these dependent on the ssl session strength */
+ HMAC_Init_ex(hctx, key->hmac_key, sizeof(key->hmac_key),
+ key->hmac_hash, NULL);
+ EVP_EncryptInit_ex(ctx, key->aes_cipher, NULL, key->aes_key, iv);
+
+ DEBUG(D_tls) debug_printf("ticket created\n");
+ return 1;
+ }
+else
+ {
+ time_t now = time(NULL);
+
+ DEBUG(D_tls) debug_printf("ticket_key_callback: retrieve session\n");
+ tlsp->resumption |= RESUME_CLIENT_SUGGESTED;
+
+ if (!(key = tk_find(key_name)) || key->expire < now)
+ {
+ DEBUG(D_tls)
+ {
+ debug_printf("ticket not usable (%s)\n", key ? "expired" : "not found");
+ if (key) debug_printf("STEK expire %ld\n", key->expire - now);
+ }
+ return 0;
+ }
+
+ HMAC_Init_ex(hctx, key->hmac_key, sizeof(key->hmac_key),
+ key->hmac_hash, NULL);
+ EVP_DecryptInit_ex(ctx, key->aes_cipher, NULL, key->aes_key, iv);
+
+ DEBUG(D_tls) debug_printf("ticket usable, STEK expire %ld\n", key->expire - now);
+ return key->renew < now ? 2 : 1;
+ }
+}
+#endif
+
+
/*************************************************
* Initialize for DH *
arg Callback of "our" registered data
Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
+
+XXX might need to change to using ClientHello callback,
+per https://www.openssl.org/docs/manmaster/man3/SSL_client_hello_cb_fn.html
*/
#ifdef EXIM_HAVE_OPENSSL_TLSEXT
#ifndef DISABLE_OCSP
uschar *ocsp_file, /*XXX stack, in server*/
#endif
- address_item *addr, tls_ext_ctx_cb ** cbp, uschar ** errstr)
+ address_item *addr, tls_ext_ctx_cb ** cbp,
+ tls_support * tlsp,
+ uschar ** errstr)
{
SSL_CTX * ctx;
long init_options;
tls_ext_ctx_cb * cbinfo;
cbinfo = store_malloc(sizeof(tls_ext_ctx_cb));
+cbinfo->tlsp = tlsp;
cbinfo->certificate = certificate;
cbinfo->privatekey = privatekey;
cbinfo->is_server = host==NULL;
/* Set up the information callback, which outputs if debugging is at a suitable
level. */
-DEBUG(D_tls) SSL_CTX_set_info_callback(ctx, (void (*)())info_callback);
+DEBUG(D_tls)
+ {
+ SSL_CTX_set_info_callback(ctx, (void (*)())info_callback);
+#ifndef OPENSSL_NO_SSL_TRACE /* this needs a debug build of OpenSSL */
+ SSL_CTX_set_msg_callback(ctx, (void (*)())SSL_trace);
+#endif
#ifdef OPENSSL_HAVE_KEYLOG_CB
-DEBUG(D_tls) SSL_CTX_set_keylog_callback(ctx, (void (*)())keylog_callback);
+ SSL_CTX_set_keylog_callback(ctx, (void (*)())keylog_callback);
#endif
+ }
/* Automatically re-try reads/writes after renegotiation. */
(void) SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY);
if (!tls_openssl_options_parse(openssl_options, &init_options))
return tls_error(US"openssl_options parsing failed", host, NULL, errstr);
+#ifdef EXPERIMENTAL_TLS_RESUME
+tlsp->resumption = RESUME_SUPPORTED;
+#endif
if (init_options)
{
+#ifdef EXPERIMENTAL_TLS_RESUME
+ /* Should the server offer session resumption? */
+ if (!host && verify_check_host(&tls_resumption_hosts) == OK)
+ {
+ DEBUG(D_tls) debug_printf("tls_resumption_hosts overrides openssl_options\n");
+ init_options &= ~SSL_OP_NO_TICKET;
+ tlsp->resumption |= RESUME_SERVER_TICKET; /* server will give ticket on request */
+ tlsp->host_resumable = TRUE;
+ }
+#endif
+
DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options);
if (!(SSL_CTX_set_options(ctx, init_options)))
return tls_error(string_sprintf(
else
DEBUG(D_tls) debug_printf("no SSL CTX options to set\n");
-#ifdef OPENSSL_HAVE_NUM_TICKETS
-SSL_CTX_set_num_tickets(ctx, 0); /* send no TLS1.3 stateful-tickets */
-#endif
-
/* We'd like to disable session cache unconditionally, but foolish Outlook
Express clients then give up the first TLS connection and make a second one
(which works). Only when there is an IMAP service on the same machine.
SSL_CTX_set_tmp_rsa_callback(ctx, rsa_callback);
#endif
-/* Finally, set the timeout, and we are done */
+/* Finally, set the session cache timeout, and we are done.
+The period appears to be also used for (server-generated) session tickets */
SSL_CTX_set_timeout(ctx, ssl_session_timeout);
DEBUG(D_tls) debug_printf("Initialized TLS\n");
#ifndef DISABLE_OCSP
tls_ocsp_file, /*XXX stack*/
#endif
- NULL, &server_static_cbinfo, errstr);
+ NULL, &server_static_cbinfo, &tls_in, errstr);
if (rc != OK) return rc;
cbinfo = server_static_cbinfo;
if (expciphers)
{
- uschar * s = expciphers;
- while (*s != 0) { if (*s == '_') *s = '-'; s++; }
+ for (uschar * s = expciphers; *s; s++ ) if (*s == '_') *s = '-';
DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
if (!SSL_CTX_set_cipher_list(server_ctx, CS expciphers))
return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL, errstr);
server_verify_optional = TRUE;
}
+#ifdef EXPERIMENTAL_TLS_RESUME
+SSL_CTX_set_tlsext_ticket_key_cb(server_ctx, ticket_key_callback);
+/* despite working, appears to always return failure, so ignoring */
+#endif
+#ifdef OPENSSL_HAVE_NUM_TICKETS
+# ifdef EXPERIMENTAL_TLS_RESUME
+SSL_CTX_set_num_tickets(server_ctx, tls_in.host_resumable ? 1 : 0);
+# else
+SSL_CTX_set_num_tickets(server_ctx, 0); /* send no TLS1.3 stateful-tickets */
+# endif
+#endif
+
+
/* Prepare for new connection */
if (!(server_ssl = SSL_new(server_ctx)))
DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
ERR_clear_error(); /* Even success can leave errors in the stack. Seen with
- anon-authentication ciphersuite negociated. */
+ anon-authentication ciphersuite negotiated. */
+
+#ifdef EXPERIMENTAL_TLS_RESUME
+if (SSL_session_reused(server_ssl))
+ {
+ tls_in.resumption |= RESUME_USED;
+ DEBUG(D_tls) debug_printf("Session reused\n");
+ }
+#endif
/* TLS has been set up. Adjust the input functions to read via TLS,
and initialize things. */
BIO_free(bp);
}
#endif
+
+#ifdef EXIM_HAVE_SESSION_TICKET
+ {
+ SSL_SESSION * ss = SSL_get_session(server_ssl);
+ if (SSL_SESSION_has_ticket(ss))
+ debug_printf("The session has a ticket, life %lu seconds\n",
+ SSL_SESSION_get_ticket_lifetime_hint(ss));
+ }
+#endif
}
/* Record the certificate we presented */
+#ifdef EXPERIMENTAL_TLS_RESUME
+/* On the client, get any stashed session for the given IP from hints db
+and apply it to the ssl-connection for attempted resumption. */
+
+static void
+tls_retrieve_session(tls_support * tlsp, SSL * ssl, const uschar * key)
+{
+tlsp->resumption |= RESUME_SUPPORTED;
+if (tlsp->host_resumable)
+ {
+ dbdata_tls_session * dt;
+ int len;
+ open_db dbblock, * dbm_file;
+
+ tlsp->resumption |= RESUME_CLIENT_REQUESTED;
+ DEBUG(D_tls) debug_printf("checking for resumable session for %s\n", key);
+ if ((dbm_file = dbfn_open(US"tls", O_RDONLY, &dbblock, FALSE, FALSE)))
+ {
+ /* key for the db is the IP */
+ if ((dt = dbfn_read_with_length(dbm_file, key, &len)))
+ {
+ SSL_SESSION * ss = NULL;
+ const uschar * sess_asn1 = dt->session;
+
+ len -= sizeof(dbdata_tls_session);
+ if (!(d2i_SSL_SESSION(&ss, &sess_asn1, (long)len)))
+ {
+ DEBUG(D_tls)
+ {
+ ERR_error_string_n(ERR_get_error(),
+ ssl_errstring, sizeof(ssl_errstring));
+ debug_printf("decoding session: %s\n", ssl_errstring);
+ }
+ }
+ else if (!SSL_set_session(ssl, ss))
+ {
+ DEBUG(D_tls)
+ {
+ ERR_error_string_n(ERR_get_error(),
+ ssl_errstring, sizeof(ssl_errstring));
+ debug_printf("applying session to ssl: %s\n", ssl_errstring);
+ }
+ }
+ else
+ {
+ DEBUG(D_tls) debug_printf("good session\n");
+ tlsp->resumption |= RESUME_CLIENT_SUGGESTED;
+ }
+ }
+ else
+ DEBUG(D_tls) debug_printf("no session record\n");
+ dbfn_close(dbm_file);
+ }
+ }
+}
+
+
+/* On the client, save the session for later resumption */
+
+static int
+tls_save_session_cb(SSL * ssl, SSL_SESSION * ss)
+{
+tls_ext_ctx_cb * cbinfo = SSL_get_ex_data(ssl, tls_exdata_idx);
+tls_support * tlsp;
+
+DEBUG(D_tls) debug_printf("tls_save_session_cb\n");
+
+if (!cbinfo || !(tlsp = cbinfo->tlsp)->host_resumable) return 0;
+
+# ifdef EXIM_HAVE_SESSION_TICKET
+
+if (SSL_SESSION_is_resumable(ss))
+ {
+ int len = i2d_SSL_SESSION(ss, NULL);
+ int dlen = sizeof(dbdata_tls_session) + len;
+ dbdata_tls_session * dt = store_get(dlen);
+ uschar * s = dt->session;
+ open_db dbblock, * dbm_file;
+
+ DEBUG(D_tls) debug_printf("session is resumable\n");
+ tlsp->resumption |= RESUME_SERVER_TICKET; /* server gave us a ticket */
+
+ len = i2d_SSL_SESSION(ss, &s); /* s gets bumped to end */
+
+ if ((dbm_file = dbfn_open(US"tls", O_RDWR, &dbblock, FALSE, FALSE)))
+ {
+ const uschar * key = cbinfo->host->address;
+ dbfn_delete(dbm_file, key);
+ dbfn_write(dbm_file, key, dt, dlen);
+ dbfn_close(dbm_file);
+ DEBUG(D_tls) debug_printf("wrote session (len %u) to db\n",
+ (unsigned)dlen);
+ }
+ }
+# endif
+return 1;
+}
+
+
+static void
+tls_client_ctx_resume_prehandshake(
+ exim_openssl_client_tls_ctx * exim_client_ctx, tls_support * tlsp,
+ smtp_transport_options_block * ob, host_item * host)
+{
+/* Should the client request a session resumption ticket? */
+if (verify_check_given_host(CUSS &ob->tls_resumption_hosts, host) == OK)
+ {
+ tlsp->host_resumable = TRUE;
+
+ SSL_CTX_set_session_cache_mode(exim_client_ctx->ctx,
+ SSL_SESS_CACHE_CLIENT
+ | SSL_SESS_CACHE_NO_INTERNAL | SSL_SESS_CACHE_NO_AUTO_CLEAR);
+ SSL_CTX_sess_set_new_cb(exim_client_ctx->ctx, tls_save_session_cb);
+ }
+}
+
+static BOOL
+tls_client_ssl_resume_prehandshake(SSL * ssl, tls_support * tlsp,
+ host_item * host, uschar ** errstr)
+{
+if (tlsp->host_resumable)
+ {
+ DEBUG(D_tls)
+ debug_printf("tls_resumption_hosts overrides openssl_options, enabling tickets\n");
+ SSL_clear_options(ssl, SSL_OP_NO_TICKET);
+
+ tls_exdata_idx = SSL_get_ex_new_index(0, 0, 0, 0, 0);
+ if (!SSL_set_ex_data(ssl, tls_exdata_idx, client_static_cbinfo))
+ {
+ tls_error(US"set ex_data", host, NULL, errstr);
+ return FALSE;
+ }
+ debug_printf("tls_exdata_idx %d cbinfo %p\n", tls_exdata_idx, client_static_cbinfo);
+ }
+
+tlsp->resumption = RESUME_SUPPORTED;
+/* Pick up a previous session, saved on an old ticket */
+tls_retrieve_session(tlsp, ssl, host->address);
+return TRUE;
+}
+
+static void
+tls_client_resume_posthandshake(exim_openssl_client_tls_ctx * exim_client_ctx,
+ tls_support * tlsp)
+{
+if (SSL_session_reused(exim_client_ctx->ssl))
+ {
+ DEBUG(D_tls) debug_printf("The session was reused\n");
+ tlsp->resumption |= RESUME_USED;
+ }
+}
+#endif /* EXPERIMENTAL_TLS_RESUME */
+
+
/*************************************************
* Start a TLS session in a client *
*************************************************/
#ifndef DISABLE_OCSP
(void *)(long)request_ocsp,
#endif
- cookie, &client_static_cbinfo, errstr);
+ cookie, &client_static_cbinfo, tlsp, errstr);
if (rc != OK) return FALSE;
tlsp->certificate_verified = FALSE;
client_static_cbinfo, errstr) != OK)
return FALSE;
+#ifdef EXPERIMENTAL_TLS_RESUME
+tls_client_ctx_resume_prehandshake(exim_client_ctx, tlsp, ob, host);
+#endif
+
+
if (!(exim_client_ctx->ssl = SSL_new(exim_client_ctx->ctx)))
{
tls_error(US"SSL_new", host, NULL, errstr);
return FALSE;
}
SSL_set_session_id_context(exim_client_ctx->ssl, sid_ctx, Ustrlen(sid_ctx));
+
+#ifdef EXPERIMENTAL_TLS_RESUME
+if (!tls_client_ssl_resume_prehandshake(exim_client_ctx->ssl, tlsp, host,
+ errstr))
+ return FALSE;
+#endif
+
SSL_set_fd(exim_client_ctx->ssl, cctx->sock);
SSL_set_connect_state(exim_client_ctx->ssl);
#endif
}
+#ifdef EXPERIMENTAL_TLS_RESUME
+tls_client_resume_posthandshake(exim_client_ctx, tlsp);
+#endif
+
peer_cert(exim_client_ctx->ssl, tlsp, peerdn, sizeof(peerdn));
tlsp->cipher = construct_cipher_name(exim_client_ctx->ssl, &tlsp->bits);
uschar keep_c;
BOOL adding, item_parsed;
+/* Server: send no (<= TLS1.2) session tickets */
result = SSL_OP_NO_TICKET;
+
/* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
* from default because it increases BEAST susceptibility. */
#ifdef SSL_OP_NO_SSLv2
result |= SSL_OP_NO_SSLv2;
#endif
+#ifdef SSL_OP_NO_SSLv3
+result |= SSL_OP_NO_SSLv3;
+#endif
#ifdef SSL_OP_SINGLE_DH_USE
result |= SSL_OP_SINGLE_DH_USE;
#endif
return TRUE;
}
-for (uschar * s = option_spec; *s != '\0'; /**/)
+for (uschar * s = option_spec; *s; /**/)
{
while (isspace(*s)) ++s;
if (*s == '\0')
git://git.exim.org / exim.git / blobdiff