/*
* OpenVPN -- An application to securely tunnel IP networks
* over a single TCP/UDP port, with support for SSL/TLS-based
* session authentication and key exchange,
* packet encryption, packet authentication, and
* packet compression.
*
* Copyright (C) 2002-2005 OpenVPN Solutions LLC <info@openvpn.net>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program (see the file COPYING included with this
* distribution); if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/*
* The routines in this file deal with dynamically negotiating
* the data channel HMAC and cipher keys through a TLS session.
*
* Both the TLS session and the data channel are multiplexed
* over the same TCP/UDP port.
*/
#ifdef WIN32
#include "config-win32.h"
#else
#include "config.h"
#endif
#if defined(USE_CRYPTO) && defined(USE_SSL)
#include "syshead.h"
#include "ssl.h"
#include "error.h"
#include "common.h"
#include "integer.h"
#include "socket.h"
#include "thread.h"
#include "misc.h"
#include "fdmisc.h"
#include "interval.h"
#include "perf.h"
#include "status.h"
#include "gremlin.h"
#ifdef WIN32
#include "cryptoapi.h"
#endif
#include "memdbg.h"
#ifndef ENABLE_OCC
static const char ssl_default_options_string[] = "V0 UNDEF";
#endif
static inline const char *
local_options_string (const struct tls_session *session)
{
#ifdef ENABLE_OCC
return session->opt->local_options;
#else
return ssl_default_options_string;
#endif
}
#ifdef MEASURE_TLS_HANDSHAKE_STATS
static int tls_handshake_success; /* GLOBAL */
static int tls_handshake_error; /* GLOBAL */
static int tls_packets_generated; /* GLOBAL */
static int tls_packets_sent; /* GLOBAL */
#define INCR_SENT ++tls_packets_sent
#define INCR_GENERATED ++tls_packets_generated
#define INCR_SUCCESS ++tls_handshake_success
#define INCR_ERROR ++tls_handshake_error
void
show_tls_performance_stats(void)
{
msg (D_TLS_DEBUG_LOW, "TLS Handshakes, success=%f%% (good=%d, bad=%d), retransmits=%f%%",
(double) tls_handshake_success / (tls_handshake_success + tls_handshake_error) * 100.0,
tls_handshake_success, tls_handshake_error,
(double) (tls_packets_sent - tls_packets_generated) / tls_packets_generated * 100.0);
}
#else
#define INCR_SENT
#define INCR_GENERATED
#define INCR_SUCCESS
#define INCR_ERROR
#endif
#ifdef BIO_DEBUG
#warning BIO_DEBUG defined
static FILE *biofp; /* GLOBAL */
static bool biofp_toggle; /* GLOBAL */
static time_t biofp_last_open; /* GLOBAL */
static const int biofp_reopen_interval = 600; /* GLOBAL */
static void
close_biofp()
{
if (biofp)
{
ASSERT (!fclose (biofp));
biofp = NULL;
}
}
static void
open_biofp()
{
const time_t current = time (NULL);
const pid_t pid = getpid ();
if (biofp_last_open + biofp_reopen_interval < current)
close_biofp();
if (!biofp)
{
char fn[256];
openvpn_snprintf(fn, sizeof(fn), "bio/%d-%d.log", pid, biofp_toggle);
biofp = fopen (fn, "w");
ASSERT (biofp);
biofp_last_open = time (NULL);
biofp_toggle ^= 1;
}
}
static void
bio_debug_data (const char *mode, BIO *bio, const uint8_t *buf, int len, const char *desc)
{
struct gc_arena gc = gc_new ();
if (len > 0)
{
open_biofp();
fprintf(biofp, "BIO_%s %s time=" time_format " bio=" ptr_format " len=%d data=%s\n",
mode, desc, time (NULL), (ptr_type)bio, len, format_hex (buf, len, 0, &gc));
fflush (biofp);
}
gc_free (&gc);
}
static void
bio_debug_oc (const char *mode, BIO *bio)
{
open_biofp();
fprintf(biofp, "BIO %s time=" time_format " bio=" ptr_format "\n",
mode, time (NULL), (ptr_type)bio);
fflush (biofp);
}
#endif
/*
* Max number of bytes we will add
* for data structures common to both
* data and control channel packets.
* (opcode only).
*/
void
tls_adjust_frame_parameters(struct frame *frame)
{
frame_add_to_extra_frame (frame, 1); /* space for opcode */
}
/*
* Max number of bytes we will add
* to control channel packet.
*/
static void
tls_init_control_channel_frame_parameters(const struct frame *data_channel_frame,
struct frame *frame)
{
/*
* frame->extra_frame is already initialized with tls_auth buffer requirements,
* if --tls-auth is enabled.
*/
/* inherit link MTU and extra_link from data channel */
frame->link_mtu = data_channel_frame->link_mtu;
frame->extra_link = data_channel_frame->extra_link;
/* set extra_frame */
tls_adjust_frame_parameters (frame);
reliable_ack_adjust_frame_parameters (frame, CONTROL_SEND_ACK_MAX);
frame_add_to_extra_frame (frame, SID_SIZE + sizeof (packet_id_type));
/* set dynamic link MTU to minimum value */
frame_set_mtu_dynamic (frame, 0, SET_MTU_TUN);
}
/*
* Allocate space in SSL objects
* in which to store a struct tls_session
* pointer back to parent.
*/
static int mydata_index; /* GLOBAL */
static void
ssl_set_mydata_index ()
{
mydata_index = SSL_get_ex_new_index (0, "struct session *", NULL, NULL, NULL);
ASSERT (mydata_index >= 0);
}
void
init_ssl_lib ()
{
SSL_library_init ();
SSL_load_error_strings ();
OpenSSL_add_all_algorithms ();
init_crypto_lib();
/*
* If you build the OpenSSL library and OpenVPN with
* CRYPTO_MDEBUG, you will get a listing of OpenSSL
* memory leaks on program termination.
*/
#ifdef CRYPTO_MDEBUG
CRYPTO_mem_ctrl(CRYPTO_MEM_CHECK_ON);
#endif
ssl_set_mydata_index ();
}
void
free_ssl_lib ()
{
#ifdef CRYPTO_MDEBUG
FILE* fp = fopen ("sdlog", "w");
ASSERT (fp);
CRYPTO_mem_leaks_fp (fp);
fclose (fp);
#endif
uninit_crypto_lib ();
EVP_cleanup ();
ERR_free_strings ();
}
/*
* OpenSSL library calls pem_password_callback if the
* private key is protected by a password.
*/
static struct user_pass passbuf; /* GLOBAL */
void
pem_password_setup (const char *auth_file)
{
if (!strlen (passbuf.password))
get_user_pass (&passbuf, auth_file, true, UP_TYPE_PRIVATE_KEY, GET_USER_PASS_MANAGEMENT|GET_USER_PASS_SENSITIVE);
}
int
pem_password_callback (char *buf, int size, int rwflag, void *u)
{
if (buf)
{
/* prompt for password even if --askpass wasn't specified */
pem_password_setup (NULL);
strncpynt (buf, passbuf.password, size);
purge_user_pass (&passbuf, false);
return strlen (buf);
}
return 0;
}
/*
* Auth username/password handling
*/
static bool auth_user_pass_enabled; /* GLOBAL */
static struct user_pass auth_user_pass; /* GLOBAL */
void
auth_user_pass_setup (const char *auth_file)
{
auth_user_pass_enabled = true;
if (!auth_user_pass.defined)
get_user_pass (&auth_user_pass, auth_file, false, UP_TYPE_AUTH, GET_USER_PASS_MANAGEMENT|GET_USER_PASS_SENSITIVE);
}
/*
* Disable password caching
*/
void
ssl_set_auth_nocache (void)
{
passbuf.nocache = true;
auth_user_pass.nocache = true;
}
/*
* Forget private key password AND auth-user-pass username/password.
*/
void
ssl_purge_auth (void)
{
#if 1 /* JYFIXME -- todo: bad private key should trigger a signal, then this code can be included */
purge_user_pass (&passbuf, true);
#endif
purge_user_pass (&auth_user_pass, true);
}
/*
* OpenSSL callback to get a temporary RSA key, mostly
* used for export ciphers.
*/
static RSA *
tmp_rsa_cb (SSL * s, int is_export, int keylength)
{
static RSA *rsa_tmp = NULL;
if (rsa_tmp == NULL)
{
msg (D_HANDSHAKE, "Generating temp (%d bit) RSA key", keylength);
rsa_tmp = RSA_generate_key (keylength, RSA_F4, NULL, NULL);
}
return (rsa_tmp);
}
/*
* Extract a field from an X509 subject name.
*
* Example:
*
* /C=US/ST=CO/L=Denver/O=ORG/CN=Test-CA/Email=jim@yonan.net
*
* The common name is 'Test-CA'
*/
static void
extract_x509_field (const char *x509, const char *field_name, char *out, int size)
{
char field_buf[256];
struct buffer x509_buf;
ASSERT (size > 0);
*out = '\0';
buf_set_read (&x509_buf, (uint8_t *)x509, strlen (x509));
while (buf_parse (&x509_buf, '/', field_buf, sizeof (field_buf)))
{
struct buffer component_buf;
char field_name_buf[64];
char field_value_buf[256];
buf_set_read (&component_buf, (const uint8_t *) field_buf, strlen (field_buf));
buf_parse (&component_buf, '=', field_name_buf, sizeof (field_name_buf));
buf_parse (&component_buf, '=', field_value_buf, sizeof (field_value_buf));
if (!strcmp (field_name_buf, field_name))
{
strncpynt (out, field_value_buf, size);
break;
}
}
}
static void
setenv_untrusted (struct tls_session *session)
{
setenv_sockaddr (session->opt->es, "untrusted", &session->untrusted_sockaddr, SA_IP_PORT);
}
static void
set_common_name (struct tls_session *session, const char *common_name)
{
if (session->common_name)
{
free (session->common_name);
session->common_name = NULL;
}
if (common_name)
{
session->common_name = string_alloc (common_name, NULL);
}
}
/*
* nsCertType checking
*/
#define verify_nsCertType(x, usage) (((x)->ex_flags & EXFLAG_NSCERT) && ((x)->ex_nscert & (usage)))
static const char *
print_nsCertType (int type)
{
switch (type)
{
case NS_SSL_SERVER:
return "SERVER";
case NS_SSL_CLIENT:
return "CLIENT";
default:
return "?";
}
}
/*
* Our verify callback function -- check
* that an incoming peer certificate is good.
*/
static int
verify_callback (int preverify_ok, X509_STORE_CTX * ctx)
{
char subject[256];
char envname[64];
char common_name[TLS_CN_LEN];
SSL *ssl;
struct tls_session *session;
const struct tls_options *opt;
const int max_depth = 8;
/* get the tls_session pointer */
ssl = X509_STORE_CTX_get_ex_data (ctx, SSL_get_ex_data_X509_STORE_CTX_idx());
ASSERT (ssl);
session = (struct tls_session *) SSL_get_ex_data (ssl, mydata_index);
ASSERT (session);
opt = session->opt;
ASSERT (opt);
session->verified = false;
/* get the X509 name */
X509_NAME_oneline (X509_get_subject_name (ctx->current_cert), subject,
sizeof (subject));
subject[sizeof (subject) - 1] = '\0';
/* enforce character class restrictions in X509 name */
string_mod (subject, X509_NAME_CHAR_CLASS, 0, '_');
/* extract the common name */
extract_x509_field (subject, "CN", common_name, TLS_CN_LEN);
string_mod (common_name, COMMON_NAME_CHAR_CLASS, 0, '_');
#if 0 /* print some debugging info */
msg (D_LOW, "LOCAL OPT: %s", opt->local_options);
msg (D_LOW, "X509: %s", subject);
#endif
/* did peer present cert which was signed our root cert? */
if (!preverify_ok)
{
/* Remote site specified a certificate, but it's not correct */
msg (D_TLS_ERRORS, "VERIFY ERROR: depth=%d, error=%s: %s",
ctx->error_depth, X509_verify_cert_error_string (ctx->error), subject);
goto err; /* Reject connection */
}
/* warn if cert chain is too deep */
if (ctx->error_depth >= max_depth)
msg (M_WARN, "TLS Warning: Convoluted certificate chain detected with depth [%d] greater than %d", ctx->error_depth, max_depth);
/* save common name in session object */
if (ctx->error_depth == 0)
set_common_name (session, common_name);
/* export subject name string as environmental variable */
session->verify_maxlevel = max_int (session->verify_maxlevel, ctx->error_depth);
openvpn_snprintf (envname, sizeof(envname), "tls_id_%d", ctx->error_depth);
setenv_str (opt->es, envname, subject);
#if 0
/* export common name string as environmental variable */
openvpn_snprintf (envname, sizeof(envname), "tls_common_name_%d", ctx->error_depth);
setenv_str (opt->es, envname, common_name);
#endif
/* export serial number as environmental variable */
{
const int serial = (int) ASN1_INTEGER_get (X509_get_serialNumber (ctx->current_cert));
openvpn_snprintf (envname, sizeof(envname), "tls_serial_%d", ctx->error_depth);
setenv_int (opt->es, envname, serial);
}
/* export current untrusted IP */
setenv_untrusted (session);
/* verify certificate nsCertType */
if (opt->ns_cert_type && ctx->error_depth == 0)
{
if (verify_nsCertType (ctx->current_cert, opt->ns_cert_type))
{
msg (D_HANDSHAKE, "VERIFY OK: nsCertType=%s",
print_nsCertType (opt->ns_cert_type));
}
else
{
msg (D_HANDSHAKE, "VERIFY nsCertType ERROR: %s, require nsCertType=%s",
subject, print_nsCertType (opt->ns_cert_type));
goto err; /* Reject connection */
}
}
/* verify X509 name or common name against --tls-remote */
if (opt->verify_x509name && strlen (opt->verify_x509name) > 0 && ctx->error_depth == 0)
{
if (strcmp (opt->verify_x509name, subject) == 0
|| strncmp (opt->verify_x509name, common_name, strlen (opt->verify_x509name)) == 0)
msg (D_HANDSHAKE, "VERIFY X509NAME OK: %s", subject);
else
{
msg (D_HANDSHAKE, "VERIFY X509NAME ERROR: %s, must be %s",
subject, opt->verify_x509name);
goto err; /* Reject connection */
}
}
/* call --tls-verify plug-in(s) */
if (plugin_defined (opt->plugins, OPENVPN_PLUGIN_TLS_VERIFY))
{
char command[256];
struct buffer out;
int ret;
buf_set_write (&out, (uint8_t*)command, sizeof (command));
buf_printf (&out, "%d %s",
ctx->error_depth,
subject);
ret = plugin_call (opt->plugins, OPENVPN_PLUGIN_TLS_VERIFY, command, NULL, opt->es);
if (!ret)
{
msg (D_HANDSHAKE, "VERIFY PLUGIN OK: depth=%d, %s",
ctx->error_depth, subject);
}
else
{
msg (D_HANDSHAKE, "VERIFY PLUGIN ERROR: depth=%d, %s",
ctx->error_depth, subject);
goto err; /* Reject connection */
}
}
/* run --tls-verify script */
if (opt->verify_command)
{
char command[256];
struct buffer out;
int ret;
setenv_str (opt->es, "script_type", "tls-verify");
buf_set_write (&out, (uint8_t*)command, sizeof (command));
buf_printf (&out, "%s %d %s",
opt->verify_command,
ctx->error_depth,
subject);
dmsg (D_TLS_DEBUG, "TLS: executing verify command: %s", command);
ret = openvpn_system (command, opt->es, S_SCRIPT);
if (system_ok (ret))
{
msg (D_HANDSHAKE, "VERIFY SCRIPT OK: depth=%d, %s",
ctx->error_depth, subject);
}
else
{
if (!system_executed (ret))
msg (M_ERR, "Verify command failed to execute: %s", command);
msg (D_HANDSHAKE, "VERIFY SCRIPT ERROR: depth=%d, %s",
ctx->error_depth, subject);
goto err; /* Reject connection */
}
}
/* check peer cert against CRL */
if (opt->crl_file)
{
X509_CRL *crl=NULL;
X509_REVOKED *revoked;
BIO *in=NULL;
int n,i,retval = 0;
in=BIO_new(BIO_s_file());
if (in == NULL) {
msg (M_ERR, "CRL: BIO err");
goto end;
}
if (BIO_read_filename(in, opt->crl_file) <= 0) {
msg (M_ERR, "CRL: cannot read: %s", opt->crl_file);
goto end;
}
crl=PEM_read_bio_X509_CRL(in,NULL,NULL,NULL);
if (crl == NULL) {
msg (M_ERR, "CRL: cannot read CRL from file %s", opt->crl_file);
goto end;
}
if (X509_NAME_cmp(X509_CRL_get_issuer(crl), X509_get_issuer_name(ctx->current_cert)) != 0) {
msg (M_WARN, "CRL: CRL %s is from a different issuer than the issuer of certificate %s", opt->crl_file, subject);
retval = 1;
goto end;
}
n = sk_num(X509_CRL_get_REVOKED(crl));
for (i = 0; i < n; i++) {
revoked = (X509_REVOKED *)sk_value(X509_CRL_get_REVOKED(crl), i);
if (ASN1_INTEGER_cmp(revoked->serialNumber, X509_get_serialNumber(ctx->current_cert)) == 0) {
msg (D_HANDSHAKE, "CRL CHECK FAILED: %s is REVOKED",subject);
goto end;
}
}
retval = 1;
msg (D_HANDSHAKE, "CRL CHECK OK: %s",subject);
end:
BIO_free(in);
if (crl)
X509_CRL_free (crl);
if (!retval)
goto err;
}
msg (D_HANDSHAKE, "VERIFY OK: depth=%d, %s", ctx->error_depth, subject);
session->verified = true;
return 1; /* Accept connection */
err:
ERR_clear_error ();
return 0; /* Reject connection */
}
void
tls_set_common_name (struct tls_multi *multi, const char *common_name)
{
if (multi)
set_common_name (&multi->session[TM_ACTIVE], common_name);
}
const char *
tls_common_name (struct tls_multi *multi, bool null)
{
const char *ret = NULL;
if (multi)
ret = multi->session[TM_ACTIVE].common_name;
if (ret && strlen (ret))
return ret;
else if (null)
return NULL;
else
return "UNDEF";
}
void
tls_lock_common_name (struct tls_multi *multi)
{
const char *cn = multi->session[TM_ACTIVE].common_name;
if (cn && !multi->locked_cn)
multi->locked_cn = string_alloc (cn, NULL);
}
/*
* Return true if at least one valid key state exists
* which has passed authentication. If we are using
* username/password authentication, and the authentication
* failed, we may have a live S_ACTIVE/S_NORMAL key state
* even though the 'authenticated' var might be false.
*
* This is so that we can return an AUTH_FAILED error
* message to the client over the TLS channel.
*
* If 'authenticated' is false, tunnel traffic forwarding
* is disabled but TLS channel data can still be sent
* or received.
*/
bool
tls_authenticated (struct tls_multi *multi)
{
if (multi)
{
int i;
for (i = 0; i < KEY_SCAN_SIZE; ++i)
{
const struct key_state *ks = multi->key_scan[i];
if (DECRYPT_KEY_ENABLED (multi, ks) && ks->authenticated)
return true;
}
}
return false;
}
void
tls_deauthenticate (struct tls_multi *multi)
{
if (multi)
{
int i, j;
for (i = 0; i < TM_SIZE; ++i)
for (j = 0; j < KS_SIZE; ++j)
multi->session[i].key[j].authenticated = false;
}
}
/*
* Print debugging information on SSL/TLS session negotiation.
*/
static void
info_callback (INFO_CALLBACK_SSL_CONST SSL * s, int where, int ret)
{
if (where & SSL_CB_LOOP)
{
dmsg (D_HANDSHAKE_VERBOSE, "SSL state (%s): %s",
where & SSL_ST_CONNECT ? "connect" :
where & SSL_ST_ACCEPT ? "accept" :
"undefined", SSL_state_string_long (s));
}
else if (where & SSL_CB_ALERT)
{
dmsg (D_HANDSHAKE_VERBOSE, "SSL alert (%s): %s: %s",
where & SSL_CB_READ ? "read" : "write",
SSL_alert_type_string_long (ret),
SSL_alert_desc_string_long (ret));
}
}
/*
* Initialize SSL context.
* All files are in PEM format.
*/
SSL_CTX *
init_ssl (const struct options *options)
{
SSL_CTX *ctx = NULL;
DH *dh;
BIO *bio;
bool using_cert_file = false;
ERR_clear_error ();
if (options->tls_server)
{
ctx = SSL_CTX_new (TLSv1_server_method ());
if (ctx == NULL)
msg (M_SSLERR, "SSL_CTX_new TLSv1_server_method");
SSL_CTX_set_tmp_rsa_callback (ctx, tmp_rsa_cb);
/* Get Diffie Hellman Parameters */
if (!(bio = BIO_new_file (options->dh_file, "r")))
msg (M_SSLERR, "Cannot open %s for DH parameters", options->dh_file);
dh = PEM_read_bio_DHparams (bio, NULL, NULL, NULL);
BIO_free (bio);
if (!dh)
msg (M_SSLERR, "Cannot load DH parameters from %s", options->dh_file);
if (!SSL_CTX_set_tmp_dh (ctx, dh))
msg (M_SSLERR, "SSL_CTX_set_tmp_dh");
msg (D_TLS_DEBUG_LOW, "Diffie-Hellman initialized with %d bit key",
8 * DH_size (dh));
DH_free (dh);
}
else /* if client */
{
ctx = SSL_CTX_new (TLSv1_client_method ());
if (ctx == NULL)
msg (M_SSLERR, "SSL_CTX_new TLSv1_client_method");
}
/* Set SSL options */
SSL_CTX_set_session_cache_mode (ctx, SSL_SESS_CACHE_OFF);
SSL_CTX_set_options (ctx, SSL_OP_SINGLE_DH_USE);
/* Set callback for getting password from user to decrypt private key */
SSL_CTX_set_default_passwd_cb (ctx, pem_password_callback);
if (options->pkcs12_file)
{
/* Use PKCS #12 file for key, cert and CA certs */
FILE *fp;
EVP_PKEY *pkey;
X509 *cert;
STACK_OF(X509) *ca = NULL;
PKCS12 *p12;
int i;
char password[256];
/* Load the PKCS #12 file */
if (!(fp = fopen(options->pkcs12_file, "rb")))
msg (M_SSLERR, "Error opening file %s", options->pkcs12_file);
p12 = d2i_PKCS12_fp(fp, NULL);
fclose (fp);
if (!p12) msg (M_SSLERR, "Error reading PKCS#12 file %s", options->pkcs12_file);
/* Parse the PKCS #12 file */
if (!PKCS12_parse(p12, "", &pkey, &cert, &ca))
{
pem_password_callback (password, sizeof(password) - 1, 0, NULL);
/* Reparse the PKCS #12 file with password */
ca = NULL;
if (!PKCS12_parse(p12, password, &pkey, &cert, &ca))
{
PKCS12_free(p12);
msg (M_WARN|M_SSL, "Error parsing PKCS#12 file %s", options->pkcs12_file);
goto err;
}
}
PKCS12_free(p12);
/* Load Certificate */
if (!SSL_CTX_use_certificate (ctx, cert))
msg (M_SSLERR, "Cannot use certificate");
/* Load Private Key */
if (!SSL_CTX_use_PrivateKey (ctx, pkey))
msg (M_SSLERR, "Cannot use private key");
warn_if_group_others_accessible (options->pkcs12_file);
/* Check Private Key */
if (!SSL_CTX_check_private_key (ctx))
msg (M_SSLERR, "Private key does not match the certificate");
/* Set Certificate Verification chain */
if (ca && sk_num(ca))
{
for (i = 0; i < sk_X509_num(ca); i++)
{
if (!X509_STORE_add_cert(ctx->cert_store,sk_X509_value(ca, i)))
msg (M_SSLERR, "Cannot add certificate to certificate chain (X509_STORE_add_cert)");
if (!SSL_CTX_add_client_CA(ctx, sk_X509_value(ca, i)))
msg (M_SSLERR, "Cannot add certificate to client CA list (SSL_CTX_add_client_CA)");
}
}
}
else
{
/* Use seperate PEM files for key, cert and CA certs */
#ifdef WIN32
if (options->cryptoapi_cert)
{
/* Load Certificate and Private Key */
if (!SSL_CTX_use_CryptoAPI_certificate (ctx, options->cryptoapi_cert))
msg (M_SSLERR, "Cannot load certificate \"%s\" from Microsoft Certificate Store",
options->cryptoapi_cert);
}
else
#endif
{
/* Load Certificate */
if (options->cert_file)
{
using_cert_file = true;
if (!SSL_CTX_use_certificate_file (ctx, options->cert_file, SSL_FILETYPE_PEM))
msg (M_SSLERR, "Cannot load certificate file %s", options->cert_file);
}
/* Load Private Key */
if (options->priv_key_file)
{
if (!SSL_CTX_use_PrivateKey_file (ctx, options->priv_key_file, SSL_FILETYPE_PEM))
{
#ifdef ENABLE_MANAGEMENT
if (management && (ERR_GET_REASON (ERR_peek_error()) == EVP_R_BAD_DECRYPT))
management_auth_failure (management, UP_TYPE_PRIVATE_KEY);
#endif
msg (M_WARN|M_SSL, "Cannot load private key file %s", options->priv_key_file);
goto err;
}
warn_if_group_others_accessible (options->priv_key_file);
/* Check Private Key */
if (!SSL_CTX_check_private_key (ctx))
msg (M_SSLERR, "Private key does not match the certificate");
}
}
/* Load CA file for verifying peer supplied certificate */
ASSERT (options->ca_file);
if (!SSL_CTX_load_verify_locations (ctx, options->ca_file, NULL))
msg (M_SSLERR, "Cannot load CA certificate file %s (SSL_CTX_load_verify_locations)", options->ca_file);
/* Load names of CAs from file and use it as a client CA list */
{
STACK_OF(X509_NAME) *cert_names;
cert_names = SSL_load_client_CA_file (options->ca_file);
if (!cert_names)
msg (M_SSLERR, "Cannot load CA certificate file %s (SSL_load_client_CA_file)", options->ca_file);
SSL_CTX_set_client_CA_list (ctx, cert_names);
}
}
/* Enable the use of certificate chains */
if (using_cert_file)
{
if (!SSL_CTX_use_certificate_chain_file (ctx, options->cert_file))
msg (M_SSLERR, "Cannot load certificate chain file %s (SSL_use_certificate_chain_file)", options->cert_file);
}
/* Require peer certificate verification */
#if P2MP_SERVER
if (options->client_cert_not_required)
{
msg (M_WARN, "WARNING: This configuration may accept clients which do not present a certificate");
}
else
#endif
SSL_CTX_set_verify (ctx, SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT,
verify_callback);
/* Connection information callback */
SSL_CTX_set_info_callback (ctx, info_callback);
/* Allowable ciphers */
if (options->cipher_list)
{
if (!SSL_CTX_set_cipher_list (ctx, options->cipher_list))
msg (M_SSLERR, "Problem with cipher list: %s", options->cipher_list);
}
ERR_clear_error ();
return ctx;
err:
ERR_clear_error ();
if (ctx)
SSL_CTX_free (ctx);
return NULL;
}
/*
* Print a one line summary of SSL/TLS session handshake.
*/
static void
print_details (SSL * c_ssl, const char *prefix)
{
SSL_CIPHER *ciph;
X509 *cert;
char s1[256];
char s2[256];
s1[0] = s2[0] = 0;
ciph = SSL_get_current_cipher (c_ssl);
openvpn_snprintf (s1, sizeof (s1), "%s %s, cipher %s %s",
prefix,
SSL_get_version (c_ssl),
SSL_CIPHER_get_version (ciph),
SSL_CIPHER_get_name (ciph));
cert = SSL_get_peer_certificate (c_ssl);
if (cert != NULL)
{
EVP_PKEY *pkey = X509_get_pubkey (cert);
if (pkey != NULL)
{
if (pkey->type == EVP_PKEY_RSA && pkey->pkey.rsa != NULL
&& pkey->pkey.rsa->n != NULL)
{
openvpn_snprintf (s2, sizeof (s2), ", %d bit RSA",
BN_num_bits (pkey->pkey.rsa->n));
}
else if (pkey->type == EVP_PKEY_DSA && pkey->pkey.dsa != NULL
&& pkey->pkey.dsa->p != NULL)
{
openvpn_snprintf (s2, sizeof (s2), ", %d bit DSA",
BN_num_bits (pkey->pkey.dsa->p));
}
EVP_PKEY_free (pkey);
}
X509_free (cert);
}
/* The SSL API does not allow us to look at temporary RSA/DH keys,
* otherwise we should print their lengths too */
msg (D_HANDSHAKE, "%s%s", s1, s2);
}
/*
* Show the TLS ciphers that are available for us to use
* in the OpenSSL library.
*/
void
show_available_tls_ciphers ()
{
SSL_CTX *ctx;
SSL *ssl;
const char *cipher_name;
int priority = 0;
ctx = SSL_CTX_new (TLSv1_method ());
if (!ctx)
msg (M_SSLERR, "Cannot create SSL_CTX object");
ssl = SSL_new (ctx);
if (!ssl)
msg (M_SSLERR, "Cannot create SSL object");
printf ("Available TLS Ciphers,\n");
printf ("listed in order of preference:\n\n");
while ((cipher_name = SSL_get_cipher_list (ssl, priority++)))
printf ("%s\n", cipher_name);
printf ("\n");
SSL_free (ssl);
SSL_CTX_free (ctx);
}
/*
* The OpenSSL library has a notion of preference in TLS
* ciphers. Higher preference == more secure.
* Return the highest preference cipher.
*/
void
get_highest_preference_tls_cipher (char *buf, int size)
{
SSL_CTX *ctx;
SSL *ssl;
const char *cipher_name;
ctx = SSL_CTX_new (TLSv1_method ());
if (!ctx)
msg (M_SSLERR, "Cannot create SSL_CTX object");
ssl = SSL_new (ctx);
if (!ssl)
msg (M_SSLERR, "Cannot create SSL object");
cipher_name = SSL_get_cipher_list (ssl, 0);
strncpynt (buf, cipher_name, size);
SSL_free (ssl);
SSL_CTX_free (ctx);
}
/*
* Map internal constants to ascii names.
*/
static const char *
state_name (int state)
{
switch (state)
{
case S_UNDEF:
return "S_UNDEF";
case S_INITIAL:
return "S_INITIAL";
case S_PRE_START:
return "S_PRE_START";
case S_START:
return "S_START";
case S_SENT_KEY:
return "S_SENT_KEY";
case S_GOT_KEY:
return "S_GOT_KEY";
case S_ACTIVE:
return "S_ACTIVE";
case S_NORMAL:
return "S_NORMAL";
case S_ERROR:
return "S_ERROR";
default:
return "S_???";
}
}
static const char *
packet_opcode_name (int op)
{
switch (op)
{
case P_CONTROL_HARD_RESET_CLIENT_V1:
return "P_CONTROL_HARD_RESET_CLIENT_V1";
case P_CONTROL_HARD_RESET_SERVER_V1:
return "P_CONTROL_HARD_RESET_SERVER_V1";
case P_CONTROL_HARD_RESET_CLIENT_V2:
return "P_CONTROL_HARD_RESET_CLIENT_V2";
case P_CONTROL_HARD_RESET_SERVER_V2:
return "P_CONTROL_HARD_RESET_SERVER_V2";
case P_CONTROL_SOFT_RESET_V1:
return "P_CONTROL_SOFT_RESET_V1";
case P_CONTROL_V1:
return "P_CONTROL_V1";
case P_ACK_V1:
return "P_ACK_V1";
case P_DATA_V1:
return "P_DATA_V1";
default:
return "P_???";
}
}
static const char *
session_index_name (int index)
{
switch (index)
{
case TM_ACTIVE:
return "TM_ACTIVE";
case TM_UNTRUSTED:
return "TM_UNTRUSTED";
case TM_LAME_DUCK:
return "TM_LAME_DUCK";
default:
return "TM_???";
}
}
/*
* For debugging.
*/
static const char *
print_key_id (struct tls_multi *multi, struct gc_arena *gc)
{
int i;
struct buffer out = alloc_buf_gc (256, gc);
for (i = 0; i < KEY_SCAN_SIZE; ++i)
{
struct key_state *ks = multi->key_scan[i];
buf_printf (&out, " [key#%d state=%s id=%d sid=%s]", i,
state_name (ks->state), ks->key_id,
session_id_print (&ks->session_id_remote, gc));
}
return BSTR (&out);
}
/*
* Given a key_method, return true if op
* represents the required form of hard_reset.
*
* If key_method = 0, return true if any
* form of hard reset is used.
*/
static bool
is_hard_reset (int op, int key_method)
{
if (!key_method || key_method == 1)
if (op == P_CONTROL_HARD_RESET_CLIENT_V1 || op == P_CONTROL_HARD_RESET_SERVER_V1)
return true;
if (!key_method || key_method >= 2)
if (op == P_CONTROL_HARD_RESET_CLIENT_V2 || op == P_CONTROL_HARD_RESET_SERVER_V2)
return true;
return false;
}
/*
* OpenVPN's interface to SSL/TLS authentication,
* encryption, and decryption is exclusively
* through "memory BIOs".
*/
static BIO *
getbio (BIO_METHOD * type, const char *desc)
{
BIO *ret;
ret = BIO_new (type);
if (!ret)
msg (M_SSLERR, "Error creating %s BIO", desc);
return ret;
}
/*
* Write to an OpenSSL BIO in non-blocking mode.
*/
static int
bio_write (struct tls_multi* multi, BIO *bio, const uint8_t *data, int size, const char *desc)
{
int i;
int ret = 0;
ASSERT (size >= 0);
if (size)
{
/*
* Free the L_TLS lock prior to calling BIO routines
* so that foreground thread can still call
* tls_pre_decrypt or tls_pre_encrypt,
* allowing tunnel packet forwarding to continue.
*/
#ifdef BIO_DEBUG
bio_debug_data ("write", bio, data, size, desc);
#endif
i = BIO_write (bio, data, size);
if (i < 0)
{
if (BIO_should_retry (bio))
{
;
}
else
{
msg (D_TLS_ERRORS | M_SSL, "TLS ERROR: BIO write %s error",
desc);
ret = -1;
ERR_clear_error ();
}
}
else if (i != size)
{
msg (D_TLS_ERRORS | M_SSL,
"TLS ERROR: BIO write %s incomplete %d/%d", desc, i, size);
ret = -1;
ERR_clear_error ();
}
else
{ /* successful write */
dmsg (D_HANDSHAKE_VERBOSE, "BIO write %s %d bytes", desc, i);
ret = 1;
}
}
return ret;
}
/*
* Read from an OpenSSL BIO in non-blocking mode.
*/
static int
bio_read (struct tls_multi* multi, BIO *bio, struct buffer *buf, int maxlen, const char *desc)
{
int i;
int ret = 0;
ASSERT (buf->len >= 0);
if (buf->len)
{
;
}
else
{
int len = buf_forward_capacity (buf);
if (maxlen < len)
len = maxlen;
/*
* BIO_read brackets most of the serious RSA
* key negotiation number crunching.
*/
i = BIO_read (bio, BPTR (buf), len);
VALGRIND_MAKE_READABLE ((void *) &i, sizeof (i));
#ifdef BIO_DEBUG
bio_debug_data ("read", bio, BPTR (buf), i, desc);
#endif
if (i < 0)
{
if (BIO_should_retry (bio))
{
;
}
else
{
msg (D_TLS_ERRORS | M_SSL, "TLS_ERROR: BIO read %s error",
desc);
buf->len = 0;
ret = -1;
ERR_clear_error ();
}
}
else if (!i)
{
buf->len = 0;
}
else
{ /* successful read */
dmsg (D_HANDSHAKE_VERBOSE, "BIO read %s %d bytes", desc, i);
buf->len = i;
ret = 1;
VALGRIND_MAKE_READABLE ((void *) BPTR (buf), BLEN (buf));
}
}
return ret;
}
/*
* Inline functions for reading from and writing
* to BIOs.
*/
static void
bio_write_post (const int status, struct buffer *buf)
{
if (status == 1) /* success status return from bio_write? */
{
memset (BPTR (buf), 0, BLEN (buf)); /* erase data just written */
buf->len = 0;
}
}
static int
key_state_write_plaintext (struct tls_multi *multi, struct key_state *ks, struct buffer *buf)
{
int ret;
perf_push (PERF_BIO_WRITE_PLAINTEXT);
ret = bio_write (multi, ks->ssl_bio, BPTR(buf), BLEN(buf), "tls_write_plaintext");
bio_write_post (ret, buf);
perf_pop ();
return ret;
}
static int
key_state_write_plaintext_const (struct tls_multi *multi, struct key_state *ks, const uint8_t *data, int len)
{
int ret;
perf_push (PERF_BIO_WRITE_PLAINTEXT);
ret = bio_write (multi, ks->ssl_bio, data, len, "tls_write_plaintext_const");
perf_pop ();
return ret;
}
static int
key_state_write_ciphertext (struct tls_multi *multi, struct key_state *ks, struct buffer *buf)
{
int ret;
perf_push (PERF_BIO_WRITE_CIPHERTEXT);
ret = bio_write (multi, ks->ct_in, BPTR(buf), BLEN(buf), "tls_write_ciphertext");
bio_write_post (ret, buf);
perf_pop ();
return ret;
}
static int
key_state_read_plaintext (struct tls_multi *multi, struct key_state *ks, struct buffer *buf,
int maxlen)
{
int ret;
perf_push (PERF_BIO_READ_PLAINTEXT);
ret = bio_read (multi, ks->ssl_bio, buf, maxlen, "tls_read_plaintext");
perf_pop ();
return ret;
}
static int
key_state_read_ciphertext (struct tls_multi *multi, struct key_state *ks, struct buffer *buf,
int maxlen)
{
int ret;
perf_push (PERF_BIO_READ_CIPHERTEXT);
ret = bio_read (multi, ks->ct_out, buf, maxlen, "tls_read_ciphertext");
perf_pop ();
return ret;
}
/*
* Initialize a key_state. Each key_state corresponds to
* a specific SSL/TLS session.
*/
static void
key_state_init (struct tls_session *session, struct key_state *ks)
{
update_time ();
/*
* Build TLS object that reads/writes ciphertext
* to/from memory BIOs.
*/
CLEAR (*ks);
ks->ssl = SSL_new (session->opt->ssl_ctx);
if (!ks->ssl)
msg (M_SSLERR, "SSL_new failed");
/* put session * in ssl object so we can access it
from verify callback*/
SSL_set_ex_data (ks->ssl, mydata_index, session);
ks->ssl_bio = getbio (BIO_f_ssl (), "ssl_bio");
ks->ct_in = getbio (BIO_s_mem (), "ct_in");
ks->ct_out = getbio (BIO_s_mem (), "ct_out");
#ifdef BIO_DEBUG
bio_debug_oc ("open ssl_bio", ks->ssl_bio);
bio_debug_oc ("open ct_in", ks->ct_in);
bio_debug_oc ("open ct_out", ks->ct_out);
#endif
if (session->opt->server)
SSL_set_accept_state (ks->ssl);
else
SSL_set_connect_state (ks->ssl);
SSL_set_bio (ks->ssl, ks->ct_in, ks->ct_out);
BIO_set_ssl (ks->ssl_bio, ks->ssl, BIO_NOCLOSE);
/* Set control-channel initiation mode */
ks->initial_opcode = session->initial_opcode;
session->initial_opcode = P_CONTROL_SOFT_RESET_V1;
ks->state = S_INITIAL;
ks->key_id = session->key_id;
/*
* key_id increments to KEY_ID_MASK then recycles back to 1.
* This way you know that if key_id is 0, it is the first key.
*/
++session->key_id;
session->key_id &= P_KEY_ID_MASK;
if (!session->key_id)
session->key_id = 1;
/* allocate key source material object */
ALLOC_OBJ_CLEAR (ks->key_src, struct key_source2);
/* allocate reliability objects */
ALLOC_OBJ_CLEAR (ks->send_reliable, struct reliable);
ALLOC_OBJ_CLEAR (ks->rec_reliable, struct reliable);
ALLOC_OBJ_CLEAR (ks->rec_ack, struct reliable_ack);
/* allocate buffers */
ks->plaintext_read_buf = alloc_buf (PLAINTEXT_BUFFER_SIZE);
ks->plaintext_write_buf = alloc_buf (PLAINTEXT_BUFFER_SIZE);
ks->ack_write_buf = alloc_buf (BUF_SIZE (&session->opt->frame));
reliable_init (ks->send_reliable, BUF_SIZE (&session->opt->frame),
FRAME_HEADROOM (&session->opt->frame), TLS_RELIABLE_N_SEND_BUFFERS);
reliable_init (ks->rec_reliable, BUF_SIZE (&session->opt->frame),
FRAME_HEADROOM (&session->opt->frame), TLS_RELIABLE_N_REC_BUFFERS);
reliable_set_timeout (ks->send_reliable, session->opt->packet_timeout);
/* init packet ID tracker */
packet_id_init (&ks->packet_id,
session->opt->replay_window,
session->opt->replay_time);
}
static void
key_state_free (struct key_state *ks, bool clear)
{
ks->state = S_UNDEF;
if (ks->ssl) {
#ifdef BIO_DEBUG
bio_debug_oc ("close ssl_bio", ks->ssl_bio);
bio_debug_oc ("close ct_in", ks->ct_in);
bio_debug_oc ("close ct_out", ks->ct_out);
#endif
BIO_free_all(ks->ssl_bio);
SSL_free (ks->ssl);
}
free_key_ctx_bi (&ks->key);
free_buf (&ks->plaintext_read_buf);
free_buf (&ks->plaintext_write_buf);
free_buf (&ks->ack_write_buf);
if (ks->send_reliable)
{
reliable_free (ks->send_reliable);
free (ks->send_reliable);
}
if (ks->rec_reliable)
{
reliable_free (ks->rec_reliable);
free (ks->rec_reliable);
}
if (ks->rec_ack)
free (ks->rec_ack);
if (ks->key_src)
free (ks->key_src);
packet_id_free (&ks->packet_id);
if (clear)
CLEAR (*ks);
}
/*
* Must be called if we move a tls_session in memory.
*/
static inline void tls_session_set_self_referential_pointers (struct tls_session* session) {
session->tls_auth.packet_id = &session->tls_auth_pid;
}
/*
* Initialize a TLS session. A TLS session normally has 2 key_state objects,
* one for the current key, and one for the lame duck (i.e. retiring) key.
*/
static void
tls_session_init (struct tls_multi *multi, struct tls_session *session)
{
struct gc_arena gc = gc_new ();
dmsg (D_TLS_DEBUG, "TLS: tls_session_init: entry");
CLEAR (*session);
/* Set options data to point to parent's option structure */
session->opt = &multi->opt;
/* Randomize session # if it is 0 */
while (!session_id_defined(&session->session_id))
session_id_random (&session->session_id);
/* Are we a TLS server or client? */
ASSERT (session->opt->key_method >= 1);
if (session->opt->key_method == 1)
{
session->initial_opcode = session->opt->server ?
P_CONTROL_HARD_RESET_SERVER_V1 : P_CONTROL_HARD_RESET_CLIENT_V1;
}
else /* session->opt->key_method >= 2 */
{
session->initial_opcode = session->opt->server ?
P_CONTROL_HARD_RESET_SERVER_V2 : P_CONTROL_HARD_RESET_CLIENT_V2;
}
/* Initialize control channel authentication parameters */
session->tls_auth = session->opt->tls_auth;
/* Set session internal pointers (also called if session object is moved in memory) */
tls_session_set_self_referential_pointers (session);
/* initialize packet ID replay window for --tls-auth */
packet_id_init (session->tls_auth.packet_id,
session->opt->replay_window,
session->opt->replay_time);
/* load most recent packet-id to replay protect on --tls-auth */
packet_id_persist_load_obj (session->tls_auth.pid_persist, session->tls_auth.packet_id);
key_state_init (session, &session->key[KS_PRIMARY]);
dmsg (D_TLS_DEBUG, "TLS: tls_session_init: new session object, sid=%s",
session_id_print (&session->session_id, &gc));
gc_free (&gc);
}
static void
tls_session_free (struct tls_session *session, bool clear)
{
int i;
if (session->tls_auth.packet_id)
packet_id_free (session->tls_auth.packet_id);
for (i = 0; i < KS_SIZE; ++i)
key_state_free (&session->key[i], false);
if (session->common_name)
free (session->common_name);
if (clear)
CLEAR (*session);
}
static void
move_session (struct tls_multi* multi, int dest, int src, bool reinit_src)
{
msg (D_TLS_DEBUG_LOW, "TLS: move_session: dest=%s src=%s reinit_src=%d",
session_index_name(dest),
session_index_name(src),
reinit_src);
ASSERT (src != dest);
ASSERT (src >= 0 && src < TM_SIZE);
ASSERT (dest >= 0 && dest < TM_SIZE);
tls_session_free (&multi->session[dest], false);
multi->session[dest] = multi->session[src];
tls_session_set_self_referential_pointers (&multi->session[dest]);
if (reinit_src)
tls_session_init (multi, &multi->session[src]);
else
CLEAR (multi->session[src]);
dmsg (D_TLS_DEBUG, "TLS: move_session: exit");
}
static void
reset_session (struct tls_multi *multi, struct tls_session *session)
{
tls_session_free (session, false);
tls_session_init (multi, session);
}
#if 0
/*
* Transmit a TLS reset on our untrusted channel.
*/
static void
initiate_untrusted_session (struct tls_multi *multi, struct sockaddr_in *to)
{
struct tls_session *session = &multi->session[TM_UNTRUSTED];
struct key_state *ks = &session->key[KS_PRIMARY];
reset_session (multi, session);
ks->remote_addr = *to;
msg (D_TLS_DEBUG_LOW, "TLS: initiate_untrusted_session: addr=%s", print_sockaddr (to));
}
#endif
/*
* Used to determine in how many seconds we should be
* called again.
*/
static inline void
compute_earliest_wakeup (interval_t *earliest, interval_t seconds_from_now) {
if (seconds_from_now < *earliest)
*earliest = seconds_from_now;
if (*earliest < 0)
*earliest = 0;
}
/*
* Return true if "lame duck" or retiring key has expired and can
* no longer be used.
*/
static inline bool
lame_duck_must_die (const struct tls_session* session, interval_t *wakeup)
{
const struct key_state* lame = &session->key[KS_LAME_DUCK];
if (lame->state >= S_INITIAL)
{
const time_t local_now = now;
ASSERT (lame->must_die); /* a lame duck key must always have an expiration */
if (local_now < lame->must_die)
{
compute_earliest_wakeup (wakeup, lame->must_die - local_now);
return false;
}
else
return true;
}
else if (lame->state == S_ERROR)
return true;
else
return false;
}
/*
* A tls_multi object fully encapsulates OpenVPN's TLS state.
* See ssl.h for more comments.
*/
struct tls_multi *
tls_multi_init (struct tls_options *tls_options)
{
struct tls_multi *ret;
ALLOC_OBJ_CLEAR (ret, struct tls_multi);
/* get command line derived options */
ret->opt = *tls_options;
/* set up pointer to HMAC object for TLS packet authentication */
ret->opt.tls_auth.key_ctx_bi = &ret->opt.tls_auth_key;
/* set up list of keys to be scanned by data channel encrypt and decrypt routines */
ASSERT (SIZE (ret->key_scan) == 3);
ret->key_scan[0] = &ret->session[TM_ACTIVE].key[KS_PRIMARY];
ret->key_scan[1] = &ret->session[TM_ACTIVE].key[KS_LAME_DUCK];
ret->key_scan[2] = &ret->session[TM_LAME_DUCK].key[KS_LAME_DUCK];
return ret;
}
/*
* Finalize our computation of frame sizes.
*/
void
tls_multi_init_finalize (struct tls_multi* multi, const struct frame* frame)
{
tls_init_control_channel_frame_parameters (frame, &multi->opt.frame);
/* initialize the active and untrusted sessions */
tls_session_init (multi, &multi->session[TM_ACTIVE]);
if (!multi->opt.single_session)
tls_session_init (multi, &multi->session[TM_UNTRUSTED]);
}
/*
* Initialize and finalize a standalone tls-auth verification object.
*/
struct tls_auth_standalone *
tls_auth_standalone_init (struct tls_options *tls_options,
struct gc_arena *gc)
{
struct tls_auth_standalone *tas;
ALLOC_OBJ_CLEAR_GC (tas, struct tls_auth_standalone, gc);
/* set up pointer to HMAC object for TLS packet authentication */
tas->tls_auth_key = tls_options->tls_auth_key;
tas->tls_auth_options.key_ctx_bi = &tas->tls_auth_key;
tas->tls_auth_options.flags |= CO_PACKET_ID_LONG_FORM;
/* get initial frame parms, still need to finalize */
tas->frame = tls_options->frame;
return tas;
}
void
tls_auth_standalone_finalize (struct tls_auth_standalone *tas,
const struct frame *frame)
{
tls_init_control_channel_frame_parameters (frame, &tas->frame);
}
/*
* Set local and remote option compatibility strings.
* Used to verify compatibility of local and remote option
* sets.
*/
void
tls_multi_init_set_options (struct tls_multi* multi,
const char *local,
const char *remote)
{
#ifdef ENABLE_OCC
/* initialize options string */
multi->opt.local_options = local;
multi->opt.remote_options = remote;
#endif
}
void
tls_multi_free (struct tls_multi *multi, bool clear)
{
int i;
ASSERT (multi);
if (multi->locked_cn)
free (multi->locked_cn);
for (i = 0; i < TM_SIZE; ++i)
tls_session_free (&multi->session[i], false);
if (clear)
CLEAR (*multi);
free(multi);
}
/*
* Move a packet authentication HMAC + related fields to or from the front
* of the buffer so it can be processed by encrypt/decrypt.
*/
/*
* Dependent on hmac size, opcode size, and session_id size.
* Will assert if too small.
*/
#define SWAP_BUF_SIZE 256
static bool
swap_hmac (struct buffer *buf, const struct crypto_options *co, bool incoming)
{
struct key_ctx *ctx;
ASSERT (co);
ctx = (incoming ? &co->key_ctx_bi->decrypt : &co->key_ctx_bi->encrypt);
ASSERT (ctx->hmac);
{
/* hmac + packet_id (8 bytes) */
const int hmac_size = HMAC_size (ctx->hmac) + packet_id_size (true);
/* opcode + session_id */
const int osid_size = 1 + SID_SIZE;
int e1, e2;
uint8_t *b = BPTR (buf);
uint8_t buf1[SWAP_BUF_SIZE];
uint8_t buf2[SWAP_BUF_SIZE];
if (incoming)
{
e1 = osid_size;
e2 = hmac_size;
}
else
{
e1 = hmac_size;
e2 = osid_size;
}
ASSERT (e1 <= SWAP_BUF_SIZE && e2 <= SWAP_BUF_SIZE);
if (buf->len >= e1 + e2)
{
memcpy (buf1, b, e1);
memcpy (buf2, b + e1, e2);
memcpy (b, buf2, e2);
memcpy (b + e2, buf1, e1);
return true;
}
else
return false;
}
}
#undef SWAP_BUF_SIZE
/*
* Write a control channel authentication record.
*/
static void
write_control_auth (struct tls_session *session,
struct key_state *ks,
struct buffer *buf,
struct sockaddr_in *to_link_addr,
int opcode,
int max_ack,
bool prepend_ack)
{
uint8_t *header;
struct buffer null = clear_buf ();
ASSERT (addr_defined (&ks->remote_addr));
ASSERT (reliable_ack_write
(ks->rec_ack, buf, &ks->session_id_remote, max_ack, prepend_ack));
ASSERT (session_id_write_prepend (&session->session_id, buf));
ASSERT (header = buf_prepend (buf, 1));
*header = ks->key_id | (opcode << P_OPCODE_SHIFT);
if (session->tls_auth.key_ctx_bi->encrypt.hmac)
{
/* no encryption, only write hmac */
openvpn_encrypt (buf, null, &session->tls_auth, NULL);
ASSERT (swap_hmac (buf, &session->tls_auth, false));
}
*to_link_addr = ks->remote_addr;
}
/*
* Read a control channel authentication record.
*/
static bool
read_control_auth (struct buffer *buf,
const struct crypto_options *co,
const struct sockaddr_in *from)
{
struct gc_arena gc = gc_new ();
if (co->key_ctx_bi->decrypt.hmac)
{
struct buffer null = clear_buf ();
/* move the hmac record to the front of the packet */
if (!swap_hmac (buf, co, true))
{
msg (D_TLS_ERRORS,
"TLS Error: cannot locate HMAC in incoming packet from %s",
print_sockaddr (from, &gc));
gc_free (&gc);
return false;
}
/* authenticate only (no decrypt) and remove the hmac record
from the head of the buffer */
openvpn_decrypt (buf, null, co, NULL);
if (!buf->len)
{
msg (D_TLS_ERRORS,
"TLS Error: incoming packet authentication failed from %s",
print_sockaddr (from, &gc));
gc_free (&gc);
return false;
}
}
/* advance buffer pointer past opcode & session_id since our caller
already read it */
buf_advance (buf, SID_SIZE + 1);
gc_free (&gc);
return true;
}
/*
* For debugging, print contents of key_source2 structure.
*/
static void
key_source_print (const struct key_source *k,
const char *prefix)
{
struct gc_arena gc = gc_new ();
VALGRIND_MAKE_READABLE ((void *)k->pre_master, sizeof (k->pre_master));
VALGRIND_MAKE_READABLE ((void *)k->random1, sizeof (k->random1));
VALGRIND_MAKE_READABLE ((void *)k->random2, sizeof (k->random2));
dmsg (D_SHOW_KEY_SOURCE,
"%s pre_master: %s",
prefix,
format_hex (k->pre_master, sizeof (k->pre_master), 0, &gc));
dmsg (D_SHOW_KEY_SOURCE,
"%s random1: %s",
prefix,
format_hex (k->random1, sizeof (k->random1), 0, &gc));
dmsg (D_SHOW_KEY_SOURCE,
"%s random2: %s",
prefix,
format_hex (k->random2, sizeof (k->random2), 0, &gc));
gc_free (&gc);
}
static void
key_source2_print (const struct key_source2 *k)
{
key_source_print (&k->client, "Client");
key_source_print (&k->server, "Server");
}
/*
* Use the TLS PRF function for generating data channel keys.
* This code is taken from the OpenSSL library.
*
* TLS generates keys as such:
*
* master_secret[48] = PRF(pre_master_secret[48], "master secret",
* ClientHello.random[32] + ServerHello.random[32])
*
* key_block[] = PRF(SecurityParameters.master_secret[48],
* "key expansion",
* SecurityParameters.server_random[32] +
* SecurityParameters.client_random[32]);
*
* Notes:
*
* (1) key_block contains a full set of 4 keys.
* (2) The pre-master secret is generated by the client.
*/
static void
tls1_P_hash(const EVP_MD *md,
const uint8_t *sec,
int sec_len,
const uint8_t *seed,
int seed_len,
uint8_t *out,
int olen)
{
struct gc_arena gc = gc_new ();
int chunk,n;
unsigned int j;
HMAC_CTX ctx;
HMAC_CTX ctx_tmp;
uint8_t A1[EVP_MAX_MD_SIZE];
unsigned int A1_len;
#ifdef ENABLE_DEBUG
const int olen_orig = olen;
const uint8_t *out_orig = out;
#endif
dmsg (D_SHOW_KEY_SOURCE, "tls1_P_hash sec: %s", format_hex (sec, sec_len, 0, &gc));
dmsg (D_SHOW_KEY_SOURCE, "tls1_P_hash seed: %s", format_hex (seed, seed_len, 0, &gc));
chunk=EVP_MD_size(md);
HMAC_CTX_init(&ctx);
HMAC_CTX_init(&ctx_tmp);
HMAC_Init_ex(&ctx,sec,sec_len,md, NULL);
HMAC_Init_ex(&ctx_tmp,sec,sec_len,md, NULL);
HMAC_Update(&ctx,seed,seed_len);
HMAC_Final(&ctx,A1,&A1_len);
n=0;
for (;;)
{
HMAC_Init_ex(&ctx,NULL,0,NULL,NULL); /* re-init */
HMAC_Init_ex(&ctx_tmp,NULL,0,NULL,NULL); /* re-init */
HMAC_Update(&ctx,A1,A1_len);
HMAC_Update(&ctx_tmp,A1,A1_len);
HMAC_Update(&ctx,seed,seed_len);
if (olen > chunk)
{
HMAC_Final(&ctx,out,&j);
out+=j;
olen-=j;
HMAC_Final(&ctx_tmp,A1,&A1_len); /* calc the next A1 value */
}
else /* last one */
{
HMAC_Final(&ctx,A1,&A1_len);
memcpy(out,A1,olen);
break;
}
}
HMAC_CTX_cleanup(&ctx);
HMAC_CTX_cleanup(&ctx_tmp);
CLEAR (A1);
dmsg (D_SHOW_KEY_SOURCE, "tls1_P_hash out: %s", format_hex (out_orig, olen_orig, 0, &gc));
gc_free (&gc);
}
static void
tls1_PRF(uint8_t *label,
int label_len,
const uint8_t *sec,
int slen,
uint8_t *out1,
int olen)
{
struct gc_arena gc = gc_new ();
const EVP_MD *md5 = EVP_md5();
const EVP_MD *sha1 = EVP_sha1();
int len,i;
const uint8_t *S1,*S2;
uint8_t *out2;
out2 = (uint8_t *) gc_malloc (olen, false, &gc);
len=slen/2;
S1=sec;
S2= &(sec[len]);
len+=(slen&1); /* add for odd, make longer */
tls1_P_hash(md5 ,S1,len,label,label_len,out1,olen);
tls1_P_hash(sha1,S2,len,label,label_len,out2,olen);
for (i=0; i<olen; i++)
out1[i]^=out2[i];
memset (out2, 0, olen);
dmsg (D_SHOW_KEY_SOURCE, "tls1_PRF out[%d]: %s", olen, format_hex (out1, olen, 0, &gc));
gc_free (&gc);
}
static void
openvpn_PRF (const uint8_t *secret,
int secret_len,
const char *label,
const uint8_t *client_seed,
int client_seed_len,
const uint8_t *server_seed,
int server_seed_len,
const struct session_id *client_sid,
const struct session_id *server_sid,
uint8_t *output,
int output_len)
{
/* concatenate seed components */
struct buffer seed = alloc_buf (strlen (label)
+ client_seed_len
+ server_seed_len
+ SID_SIZE * 2);
ASSERT (buf_write (&seed, label, strlen (label)));
ASSERT (buf_write (&seed, client_seed, client_seed_len));
ASSERT (buf_write (&seed, server_seed, server_seed_len));
if (client_sid)
ASSERT (buf_write (&seed, client_sid->id, SID_SIZE));
if (server_sid)
ASSERT (buf_write (&seed, server_sid->id, SID_SIZE));
/* compute PRF */
tls1_PRF (BPTR(&seed), BLEN(&seed), secret, secret_len, output, output_len);
buf_clear (&seed);
free_buf (&seed);
VALGRIND_MAKE_READABLE ((void *)output, output_len);
}
/*
* Using source entropy from local and remote hosts, mix into
* master key.
*/
static bool
generate_key_expansion (struct key_ctx_bi *key,
const struct key_type *key_type,
const struct key_source2 *key_src,
const struct session_id *client_sid,
const struct session_id *server_sid,
bool server)
{
uint8_t master[48];
struct key2 key2;
bool ret = false;
int i;
CLEAR (master);
CLEAR (key2);
/* debugging print of source key material */
key_source2_print (key_src);
/* compute master secret */
openvpn_PRF (key_src->client.pre_master,
sizeof(key_src->client.pre_master),
KEY_EXPANSION_ID " master secret",
key_src->client.random1,
sizeof(key_src->client.random1),
key_src->server.random1,
sizeof(key_src->server.random1),
NULL,
NULL,
master,
sizeof(master));
/* compute key expansion */
openvpn_PRF (master,
sizeof(master),
KEY_EXPANSION_ID " key expansion",
key_src->client.random2,
sizeof(key_src->client.random2),
key_src->server.random2,
sizeof(key_src->server.random2),
client_sid,
server_sid,
(uint8_t*)key2.keys,
sizeof(key2.keys));
key2.n = 2;
key2_print (&key2, key_type, "Master Encrypt", "Master Decrypt");
/* check for weak keys */
for (i = 0; i < 2; ++i)
{
fixup_key (&key2.keys[i], key_type);
if (!check_key (&key2.keys[i], key_type))
{
msg (D_TLS_ERRORS, "TLS Error: Bad dynamic key generated");
goto exit;
}
}
/* Initialize OpenSSL key contexts */
ASSERT (server == true || server == false);
init_key_ctx (&key->encrypt,
&key2.keys[(int)server],
key_type,
DO_ENCRYPT,
"Data Channel Encrypt");
init_key_ctx (&key->decrypt,
&key2.keys[1-(int)server],
key_type,
DO_DECRYPT,
"Data Channel Decrypt");
ret = true;
exit:
CLEAR (master);
CLEAR (key2);
return ret;
}
static bool
random_bytes_to_buf (struct buffer *buf,
uint8_t *out,
int outlen)
{
if (!RAND_bytes (out, outlen))
msg (M_FATAL, "ERROR: Random number generator cannot obtain entropy for key generation [SSL]");
if (!buf_write (buf, out, outlen))
return false;
return true;
}
static bool
key_source2_randomize_write (struct key_source2 *k2,
struct buffer *buf,
bool server)
{
struct key_source *k = &k2->client;
if (server)
k = &k2->server;
CLEAR (*k);
if (!server)
{
if (!random_bytes_to_buf (buf, k->pre_master, sizeof (k->pre_master)))
return false;
}
if (!random_bytes_to_buf (buf, k->random1, sizeof (k->random1)))
return false;
if (!random_bytes_to_buf (buf, k->random2, sizeof (k->random2)))
return false;
return true;
}
static int
key_source2_read (struct key_source2 *k2,
struct buffer *buf,
bool server)
{
struct key_source *k = &k2->client;
if (!server)
k = &k2->server;
CLEAR (*k);
if (server)
{
if (!buf_read (buf, k->pre_master, sizeof (k->pre_master)))
return 0;
}
if (!buf_read (buf, k->random1, sizeof (k->random1)))
return 0;
if (!buf_read (buf, k->random2, sizeof (k->random2)))
return 0;
return 1;
}
/*
* Macros for key_state_soft_reset & tls_process
*/
#define ks (&session->key[KS_PRIMARY]) /* primary key */
#define ks_lame (&session->key[KS_LAME_DUCK]) /* retiring key */
/* true if no in/out acknowledgements pending */
#define FULL_SYNC \
(reliable_empty(ks->send_reliable) && reliable_ack_empty (ks->rec_ack))
/*
* Move the active key to the lame duck key and reinitialize the
* active key.
*/
static void
key_state_soft_reset (struct tls_session *session)
{
ks->must_die = now + session->opt->transition_window; /* remaining lifetime of old key */
key_state_free (ks_lame, false);
*ks_lame = *ks;
key_state_init (session, ks);
ks->session_id_remote = ks_lame->session_id_remote;
ks->remote_addr = ks_lame->remote_addr;
}
/*
* Read/write strings from/to a struct buffer with a u16 length prefix.
*/
static bool
write_string (struct buffer *buf, const char *str, const int maxlen)
{
const int len = strlen (str) + 1;
if (len < 1 || (maxlen >= 0 && len > maxlen))
return false;
if (!buf_write_u16 (buf, len))
return false;
if (!buf_write (buf, str, len))
return false;
return true;
}
static bool
read_string (struct buffer *buf, char *str, const unsigned int capacity)
{
const int len = buf_read_u16 (buf);
if (len < 1 || len > (int)capacity)
return false;
if (!buf_read (buf, str, len))
return false;
str[len-1] = '\0';
return true;
}
/*
* Authenticate a client using username/password.
* Runs on server.
*
* If you want to add new authentication methods,
* this is the place to start.
*/
static bool
verify_user_pass_script (struct tls_session *session, const struct user_pass *up)
{
struct gc_arena gc = gc_new ();
struct buffer cmd = alloc_buf_gc (256, &gc);
const char *tmp_file = "";
int retval;
bool ret = false;
/* Is username defined? */
if (strlen (up->username))
{
/* Set environmental variables prior to calling script */
setenv_str (session->opt->es, "script_type", "user-pass-verify");
if (session->opt->auth_user_pass_verify_script_via_file)
{
struct status_output *so;
tmp_file = create_temp_filename (session->opt->tmp_dir, &gc);
so = status_open (tmp_file, 0, -1, NULL, STATUS_OUTPUT_WRITE);
status_printf (so, "%s", up->username);
status_printf (so, "%s", up->password);
if (!status_close (so))
{
msg (D_TLS_ERRORS, "TLS Auth Error: could not write username/password to file: %s",
tmp_file);
goto done;
}
}
else
{
setenv_str (session->opt->es, "username", up->username);
setenv_str (session->opt->es, "password", up->password);
}
/* setenv incoming cert common name for script */
setenv_str (session->opt->es, "common_name", session->common_name);
/* setenv client real IP address */
setenv_untrusted (session);
/* format command line */
buf_printf (&cmd, "%s %s", session->opt->auth_user_pass_verify_script, tmp_file);
/* call command */
retval = openvpn_system (BSTR (&cmd), session->opt->es, S_SCRIPT);
/* test return status of command */
if (system_ok (retval))
ret = true;
else if (!system_executed (retval))
msg (D_TLS_ERRORS, "TLS Auth Error: user-pass-verify script failed to execute: %s", BSTR (&cmd));
if (!session->opt->auth_user_pass_verify_script_via_file)
setenv_del (session->opt->es, "password");
}
else
{
msg (D_TLS_ERRORS, "TLS Auth Error: peer provided a blank username");
}
done:
if (strlen (tmp_file) > 0)
delete_file (tmp_file);
gc_free (&gc);
return ret;
}
static bool
verify_user_pass_plugin (struct tls_session *session, const struct user_pass *up, const char *raw_username)
{
int retval;
bool ret = false;
/* Is username defined? */
if (strlen (up->username))
{
/* set username/password in private env space */
setenv_str (session->opt->es, "username", raw_username);
setenv_str (session->opt->es, "password", up->password);
/* setenv incoming cert common name for script */
setenv_str (session->opt->es, "common_name", session->common_name);
/* setenv client real IP address */
setenv_untrusted (session);
/* call command */
retval = plugin_call (session->opt->plugins, OPENVPN_PLUGIN_AUTH_USER_PASS_VERIFY, NULL, NULL, session->opt->es);
if (!retval)
ret = true;
setenv_del (session->opt->es, "password");
setenv_str (session->opt->es, "username", up->username);
}
else
{
msg (D_TLS_ERRORS, "TLS Auth Error: peer provided a blank username");
}
return ret;
}
/*
* Handle the reading and writing of key data to and from
* the TLS control channel (cleartext).
*/
static bool
key_method_1_write (struct buffer *buf, struct tls_session *session)
{
struct key key;
ASSERT (session->opt->key_method == 1);
ASSERT (buf_init (buf, 0));
generate_key_random (&key, &session->opt->key_type);
if (!check_key (&key, &session->opt->key_type))
{
msg (D_TLS_ERRORS, "TLS Error: Bad encrypting key generated");
return false;
}
if (!write_key (&key, &session->opt->key_type, buf))
{
msg (D_TLS_ERRORS, "TLS Error: write_key failed");
return false;
}
init_key_ctx (&ks->key.encrypt, &key, &session->opt->key_type,
DO_ENCRYPT, "Data Channel Encrypt");
CLEAR (key);
/* send local options string */
{
const char *local_options = local_options_string (session);
const int optlen = strlen (local_options) + 1;
if (!buf_write (buf, local_options, optlen))
{
msg (D_TLS_ERRORS, "TLS Error: KM1 write options failed");
return false;
}
}
return true;
}
static bool
key_method_2_write (struct buffer *buf, struct tls_session *session)
{
ASSERT (session->opt->key_method == 2);
ASSERT (buf_init (buf, 0));
/* write a uint32 0 */
if (!buf_write_u32 (buf, 0))
goto error;
/* write key_method + flags */
if (!buf_write_u8 (buf, (session->opt->key_method & KEY_METHOD_MASK)))
goto error;
/* write key source material */
if (!key_source2_randomize_write (ks->key_src, buf, session->opt->server))
goto error;
/* write options string */
{
if (!write_string (buf, local_options_string (session), TLS_OPTIONS_LEN))
goto error;
}
/* write username/password if specified */
if (auth_user_pass_enabled)
{
auth_user_pass_setup (NULL);
if (!write_string (buf, auth_user_pass.username, -1))
goto error;
if (!write_string (buf, auth_user_pass.password, -1))
goto error;
purge_user_pass (&auth_user_pass, false);
}
/*
* generate tunnel keys if server
*/
if (session->opt->server)
{
if (ks->authenticated)
{
if (!generate_key_expansion (&ks->key,
&session->opt->key_type,
ks->key_src,
&ks->session_id_remote,
&session->session_id,
true))
{
msg (D_TLS_ERRORS, "TLS Error: server generate_key_expansion failed");
goto error;
}
}
CLEAR (*ks->key_src);
}
return true;
error:
msg (D_TLS_ERRORS, "TLS Error: Key Method #2 write failed");
CLEAR (*ks->key_src);
return false;
}
static bool
key_method_1_read (struct buffer *buf, struct tls_session *session)
{
int status;
struct key key;
ASSERT (session->opt->key_method == 1);
if (!session->verified)
{
msg (D_TLS_ERRORS,
"TLS Error: Certificate verification failed (key-method 1)");
goto error;
}
status = read_key (&key, &session->opt->key_type, buf);
if (status != 1)
{
msg (D_TLS_ERRORS,
"TLS Error: Error reading data channel key from plaintext buffer");
goto error;
}
if (!check_key (&key, &session->opt->key_type))
{
msg (D_TLS_ERRORS, "TLS Error: Bad decrypting key received from peer");
goto error;
}
if (buf->len < 1)
{
msg (D_TLS_ERRORS, "TLS Error: Missing options string");
goto error;
}
#ifdef ENABLE_OCC
/* compare received remote options string
with our locally computed options string */
if (!session->opt->disable_occ &&
!options_cmp_equal_safe ((char *) BPTR (buf), session->opt->remote_options, buf->len))
{
options_warning_safe ((char *) BPTR (buf), session->opt->remote_options, buf->len);
}
#endif
buf_clear (buf);
init_key_ctx (&ks->key.decrypt, &key, &session->opt->key_type,
DO_DECRYPT, "Data Channel Decrypt");
CLEAR (key);
ks->authenticated = true;
return true;
error:
buf_clear (buf);
CLEAR (key);
return false;
}
static bool
key_method_2_read (struct buffer *buf, struct tls_multi *multi, struct tls_session *session)
{
struct gc_arena gc = gc_new ();
int key_method_flags;
char *options;
struct user_pass *up;
ASSERT (session->opt->key_method == 2);
/* allocate temporary objects */
ALLOC_ARRAY_CLEAR_GC (options, char, TLS_OPTIONS_LEN, &gc);
/* discard leading uint32 */
ASSERT (buf_advance (buf, 4));
/* get key method */
key_method_flags = buf_read_u8 (buf);
if ((key_method_flags & KEY_METHOD_MASK) != 2)
{
msg (D_TLS_ERRORS,
"TLS ERROR: Unknown key_method/flags=%d received from remote host",
key_method_flags);
goto error;
}
/* get key source material (not actual keys yet) */
if (!key_source2_read (ks->key_src, buf, session->opt->server))
{
msg (D_TLS_ERRORS, "TLS Error: Error reading remote data channel key source entropy from plaintext buffer");
goto error;
}
/* get options */
if (!read_string (buf, options, TLS_OPTIONS_LEN))
{
msg (D_TLS_ERRORS, "TLS Error: Failed to read required OCC options string");
goto error;
}
/* should we check username/password? */
ks->authenticated = false;
if (session->opt->auth_user_pass_verify_script
|| plugin_defined (session->opt->plugins, OPENVPN_PLUGIN_AUTH_USER_PASS_VERIFY))
{
bool s1 = true;
bool s2 = true;
char *raw_username;
/* get username/password from plaintext buffer */
ALLOC_OBJ_CLEAR_GC (up, struct user_pass, &gc);
if (!read_string (buf, up->username, USER_PASS_LEN)
|| !read_string (buf, up->password, USER_PASS_LEN))
{
msg (D_TLS_ERRORS, "TLS Error: Auth Username/Password was not provided by peer");
CLEAR (*up);
goto error;
}
/* preserve raw username before string_mod remapping, for plugins */
ALLOC_ARRAY_CLEAR_GC (raw_username, char, USER_PASS_LEN, &gc);
strcpy (raw_username, up->username);
string_mod (raw_username, CC_PRINT, CC_CRLF, '_');
/* enforce character class restrictions in username/password */
string_mod (up->username, COMMON_NAME_CHAR_CLASS, 0, '_');
string_mod (up->password, CC_PRINT, CC_CRLF, '_');
/* call plugin(s) and/or script */
if (plugin_defined (session->opt->plugins, OPENVPN_PLUGIN_AUTH_USER_PASS_VERIFY))
s1 = verify_user_pass_plugin (session, up, raw_username);
if (session->opt->auth_user_pass_verify_script)
s2 = verify_user_pass_script (session, up);
/* auth succeeded? */
if (s1 && s2)
{
ks->authenticated = true;
if (session->opt->username_as_common_name)
set_common_name (session, up->username);
msg (D_HANDSHAKE, "TLS: Username/Password authentication succeeded for username '%s' %s",
up->username,
session->opt->username_as_common_name ? "[CN SET]" : "");
}
else
{
msg (D_TLS_ERRORS, "TLS Auth Error: Auth Username/Password verification failed for peer");
}
CLEAR (*up);
}
else
{
if (!session->verified)
{
msg (D_TLS_ERRORS,
"TLS Error: Certificate verification failed (key-method 2)");
goto error;
}
ks->authenticated = true;
}
/* While it shouldn't really happen, don't allow the common name to be NULL */
if (!session->common_name)
set_common_name (session, "");
/* Don't allow the CN to change once it's been locked */
if (ks->authenticated && multi->locked_cn)
{
const char *cn = session->common_name;
if (cn && strcmp (cn, multi->locked_cn))
{
msg (D_TLS_ERRORS, "TLS Auth Error: TLS object CN attempted to change from '%s' to '%s' -- tunnel disabled",
multi->locked_cn,
cn);
/* change the common name back to its original value and disable the tunnel */
set_common_name (session, multi->locked_cn);
tls_deauthenticate (multi);
}
}
/* verify --client-config-dir based authentication */
if (ks->authenticated && session->opt->client_config_dir_exclusive)
{
const char *cn = session->common_name;
const char *path = gen_path (session->opt->client_config_dir_exclusive, cn, &gc);
if (!cn || !strcmp (cn, CCD_DEFAULT) || !test_file (path))
{
ks->authenticated = false;
msg (D_TLS_ERRORS, "TLS Auth Error: --client-config-dir authentication failed for common name '%s' file='%s'",
session->common_name,
path ? path : "UNDEF");
}
}
#ifdef ENABLE_OCC
/* check options consistency */
if (!session->opt->disable_occ &&
!options_cmp_equal (options, session->opt->remote_options))
{
options_warning (options, session->opt->remote_options);
}
#endif
buf_clear (buf);
/*
* generate tunnel keys if client
*/
if (!session->opt->server)
{
if (!generate_key_expansion (&ks->key,
&session->opt->key_type,
ks->key_src,
&session->session_id,
&ks->session_id_remote,
false))
{
msg (D_TLS_ERRORS, "TLS Error: client generate_key_expansion failed");
goto error;
}
CLEAR (*ks->key_src);
}
gc_free (&gc);
return true;
error:
CLEAR (*ks->key_src);
buf_clear (buf);
gc_free (&gc);
return false;
}
/*
* This is the primary routine for processing TLS stuff inside the
* the main event loop. When this routine exits
* with non-error status, it will set *wakeup to the number of seconds
* when it wants to be called again.
*
* Return value is true if we have placed a packet in *to_link which we
* want to send to our peer.
*/
static bool
tls_process (struct tls_multi *multi,
struct tls_session *session,
struct buffer *to_link,
struct sockaddr_in *to_link_addr,
struct link_socket_info *to_link_socket_info,
interval_t *wakeup)
{
struct gc_arena gc = gc_new ();
struct buffer *buf;
bool state_change = false;
bool active = false;
/* Make sure we were initialized and that we're not in an error state */
ASSERT (ks->state != S_UNDEF);
ASSERT (ks->state != S_ERROR);
ASSERT (session_id_defined (&session->session_id));
/* Should we trigger a soft reset? -- new key, keeps old key for a while */
if (ks->state >= S_ACTIVE &&
((session->opt->renegotiate_seconds
&& now >= ks->established + session->opt->renegotiate_seconds)
|| (session->opt->renegotiate_bytes
&& ks->n_bytes >= session->opt->renegotiate_bytes)
|| (session->opt->renegotiate_packets
&& ks->n_packets >= session->opt->renegotiate_packets)
|| (packet_id_close_to_wrapping (&ks->packet_id.send))))
{
msg (D_TLS_DEBUG_LOW, "TLS: soft reset sec=%d bytes=%d/%d pkts=%d/%d",
(int)(ks->established + session->opt->renegotiate_seconds - now),
ks->n_bytes, session->opt->renegotiate_bytes,
ks->n_packets, session->opt->renegotiate_packets);
key_state_soft_reset (session);
}
/* Kill lame duck key transition_window seconds after primary key negotiation */
if (lame_duck_must_die (session, wakeup)) {
key_state_free (ks_lame, true);
msg (D_TLS_DEBUG_LOW, "TLS: tls_process: killed expiring key");
}
/*mutex_cycle (multi->mutex);*/
do
{
update_time ();
dmsg (D_TLS_DEBUG, "TLS: tls_process: chg=%d ks=%s lame=%s to_link->len=%d wakeup=%d",
state_change,
state_name (ks->state),
state_name (ks_lame->state),
to_link->len,
*wakeup);
state_change = false;
/*
* TLS activity is finished once we get to S_ACTIVE,
* though we will still process acknowledgements.
*
* CHANGED with 2.0 -> now we may send tunnel configuration
* info over the control channel.
*/
if (true)
{
/* Initial handshake */
if (ks->state == S_INITIAL)
{
buf = reliable_get_buf_output_sequenced (ks->send_reliable);
if (buf)
{
ks->must_negotiate = now + session->opt->handshake_window;
/* null buffer */
reliable_mark_active_outgoing (ks->send_reliable, buf, ks->initial_opcode);
INCR_GENERATED;
ks->state = S_PRE_START;
state_change = true;
dmsg (D_TLS_DEBUG, "TLS: Initial Handshake, sid=%s",
session_id_print (&session->session_id, &gc));
#ifdef ENABLE_MANAGEMENT
if (management && ks->initial_opcode != P_CONTROL_SOFT_RESET_V1)
{
management_set_state (management,
OPENVPN_STATE_WAIT,
NULL,
0);
}
#endif
}
}
/* Are we timed out on receive? */
if (now >= ks->must_negotiate)
{
if (ks->state < S_ACTIVE)
{
msg (D_TLS_ERRORS,
"TLS Error: TLS key negotiation failed to occur within %d seconds (check your network connectivity)",
session->opt->handshake_window);
goto error;
}
else /* assume that ks->state == S_ACTIVE */
{
dmsg (D_TLS_DEBUG_MED, "STATE S_NORMAL");
ks->state = S_NORMAL;
ks->must_negotiate = 0;
}
}
/* Wait for Initial Handshake ACK */
if (ks->state == S_PRE_START && FULL_SYNC)
{
ks->state = S_START;
state_change = true;
dmsg (D_TLS_DEBUG_MED, "STATE S_START");
}
/* Wait for ACK */
if (((ks->state == S_GOT_KEY && !session->opt->server) ||
(ks->state == S_SENT_KEY && session->opt->server)))
{
if (FULL_SYNC)
{
ks->established = now;
dmsg (D_TLS_DEBUG_MED, "STATE S_ACTIVE");
if (check_debug_level (D_HANDSHAKE))
print_details (ks->ssl, "Control Channel:");
state_change = true;
ks->state = S_ACTIVE;
INCR_SUCCESS;
/* Set outgoing address for data channel packets */
link_socket_set_outgoing_addr (NULL, to_link_socket_info, &ks->remote_addr, session->common_name, session->opt->es);
#ifdef MEASURE_TLS_HANDSHAKE_STATS
show_tls_performance_stats();
#endif
}
}
/* Reliable buffer to outgoing TCP/UDP (send up to CONTROL_SEND_ACK_MAX ACKs
for previously received packets) */
if (!to_link->len && reliable_can_send (ks->send_reliable))
{
int opcode;
struct buffer b;
buf = reliable_send (ks->send_reliable, &opcode);
ASSERT (buf);
b = *buf;
INCR_SENT;
write_control_auth (session, ks, &b, to_link_addr, opcode,
CONTROL_SEND_ACK_MAX, true);
*to_link = b;
active = true;
state_change = true;
dmsg (D_TLS_DEBUG, "Reliable -> TCP/UDP");
break;
}
#ifndef TLS_AGGREGATE_ACK
/* Send 1 or more ACKs (each received control packet gets one ACK) */
if (!to_link->len && !reliable_ack_empty (ks->rec_ack))
{
buf = &ks->ack_write_buf;
ASSERT (buf_init (buf, FRAME_HEADROOM (&multi->opt.frame)));
write_control_auth (session, ks, buf, to_link_addr, P_ACK_V1,
RELIABLE_ACK_SIZE, false);
*to_link = *buf;
active = true;
state_change = true;
dmsg (D_TLS_DEBUG, "Dedicated ACK -> TCP/UDP");
break;
}
#endif
/* Write incoming ciphertext to TLS object */
buf = reliable_get_buf_sequenced (ks->rec_reliable);
if (buf)
{
int status = 0;
if (buf->len)
{
status = key_state_write_ciphertext (multi, ks, buf);
if (status == -1)
{
msg (D_TLS_ERRORS,
"TLS Error: Incoming Ciphertext -> TLS object write error");
goto error;
}
}
else
{
status = 1;
}
if (status == 1)
{
reliable_mark_deleted (ks->rec_reliable, buf, true);
state_change = true;
dmsg (D_TLS_DEBUG, "Incoming Ciphertext -> TLS");
}
}
/* Read incoming plaintext from TLS object */
buf = &ks->plaintext_read_buf;
if (!buf->len)
{
int status;
ASSERT (buf_init (buf, 0));
status = key_state_read_plaintext (multi, ks, buf, PLAINTEXT_BUFFER_SIZE);
update_time ();
if (status == -1)
{
msg (D_TLS_ERRORS, "TLS Error: TLS object -> incoming plaintext read error");
goto error;
}
if (status == 1)
{
state_change = true;
dmsg (D_TLS_DEBUG, "TLS -> Incoming Plaintext");
}
#if 0 /* show null plaintext reads */
if (!status)
msg (M_INFO, "TLS plaintext read -> NULL return");
#endif
}
/* Send Key */
buf = &ks->plaintext_write_buf;
if (!buf->len && ((ks->state == S_START && !session->opt->server) ||
(ks->state == S_GOT_KEY && session->opt->server)))
{
if (session->opt->key_method == 1)
{
if (!key_method_1_write (buf, session))
goto error;
}
else if (session->opt->key_method == 2)
{
if (!key_method_2_write (buf, session))
goto error;
}
else
{
ASSERT (0);
}
state_change = true;
dmsg (D_TLS_DEBUG_MED, "STATE S_SENT_KEY");
ks->state = S_SENT_KEY;
}
/* Receive Key */
buf = &ks->plaintext_read_buf;
if (buf->len
&& ((ks->state == S_SENT_KEY && !session->opt->server)
|| (ks->state == S_START && session->opt->server)))
{
if (session->opt->key_method == 1)
{
if (!key_method_1_read (buf, session))
goto error;
}
else if (session->opt->key_method == 2)
{
if (!key_method_2_read (buf, multi, session))
goto error;
}
else
{
ASSERT (0);
}
state_change = true;
dmsg (D_TLS_DEBUG_MED, "STATE S_GOT_KEY");
ks->state = S_GOT_KEY;
}
/* Write outgoing plaintext to TLS object */
buf = &ks->plaintext_write_buf;
if (buf->len)
{
int status = key_state_write_plaintext (multi, ks, buf);
if (status == -1)
{
msg (D_TLS_ERRORS,
"TLS ERROR: Outgoing Plaintext -> TLS object write error");
goto error;
}
if (status == 1)
{
state_change = true;
dmsg (D_TLS_DEBUG, "Outgoing Plaintext -> TLS");
}
}
/* Outgoing Ciphertext to reliable buffer */
if (ks->state >= S_START)
{
buf = reliable_get_buf_output_sequenced (ks->send_reliable);
if (buf)
{
int status = key_state_read_ciphertext (multi, ks, buf, PAYLOAD_SIZE_DYNAMIC (&multi->opt.frame));
if (status == -1)
{
msg (D_TLS_ERRORS,
"TLS Error: Ciphertext -> reliable TCP/UDP transport read error");
goto error;
}
if (status == 1)
{
reliable_mark_active_outgoing (ks->send_reliable, buf, P_CONTROL_V1);
INCR_GENERATED;
state_change = true;
dmsg (D_TLS_DEBUG, "Outgoing Ciphertext -> Reliable");
}
}
}
}
/*mutex_cycle (multi->mutex);*/
}
while (state_change);
update_time ();
#ifdef TLS_AGGREGATE_ACK
/* Send 1 or more ACKs (each received control packet gets one ACK) */
if (!to_link->len && !reliable_ack_empty (ks->rec_ack))
{
buf = &ks->ack_write_buf;
ASSERT (buf_init (buf, FRAME_HEADROOM (&multi->opt.frame)));
write_control_auth (session, ks, buf, to_link_addr, P_ACK_V1,
RELIABLE_ACK_SIZE, false);
*to_link = *buf;
active = true;
state_change = true;
dmsg (D_TLS_DEBUG, "Dedicated ACK -> TCP/UDP");
}
#endif
/* When should we wake up again? */
{
if (ks->state >= S_INITIAL)
{
compute_earliest_wakeup (wakeup,
reliable_send_timeout (ks->send_reliable));
if (ks->must_negotiate)
compute_earliest_wakeup (wakeup, ks->must_negotiate - now);
}
if (ks->established && session->opt->renegotiate_seconds)
compute_earliest_wakeup (wakeup,
ks->established + session->opt->renegotiate_seconds - now);
/* prevent event-loop spinning by setting minimum wakeup of 1 second */
if (*wakeup <= 0)
{
*wakeup = 1;
/* if we had something to send to remote, but to_link was busy,
let caller know we need to be called again soon */
active = true;
}
dmsg (D_TLS_DEBUG, "TLS: tls_process: timeout set to %d", *wakeup);
gc_free (&gc);
return active;
}
error:
ERR_clear_error ();
ks->state = S_ERROR;
msg (D_TLS_ERRORS, "TLS Error: TLS handshake failed");
INCR_ERROR;
gc_free (&gc);
return false;
}
#undef ks
#undef ks_lame
/*
* Called by the top-level event loop.
*
* Basically decides if we should call tls_process for
* the active or untrusted sessions.
*/
bool
tls_multi_process (struct tls_multi *multi,
struct buffer *to_link,
struct sockaddr_in *to_link_addr,
struct link_socket_info *to_link_socket_info,
interval_t *wakeup)
{
struct gc_arena gc = gc_new ();
int i;
bool active = false;
bool error = false;
perf_push (PERF_TLS_MULTI_PROCESS);
ERR_clear_error ();
/*
* Process each session object having state of S_INITIAL or greater,
* and which has a defined remote IP addr.
*/
for (i = 0; i < TM_SIZE; ++i)
{
struct tls_session *session = &multi->session[i];
struct key_state *ks = &session->key[KS_PRIMARY];
struct key_state *ks_lame = &session->key[KS_LAME_DUCK];
/* set initial remote address */
if (i == TM_ACTIVE && ks->state == S_INITIAL &&
addr_defined (&to_link_socket_info->lsa->actual))
ks->remote_addr = to_link_socket_info->lsa->actual;
dmsg (D_TLS_DEBUG,
"TLS: tls_multi_process: i=%d state=%s, mysid=%s, stored-sid=%s, stored-ip=%s",
i,
state_name (ks->state),
session_id_print (&session->session_id, &gc),
session_id_print (&ks->session_id_remote, &gc),
print_sockaddr (&ks->remote_addr, &gc));
if (ks->state >= S_INITIAL && addr_defined (&ks->remote_addr))
{
update_time ();
if (tls_process (multi, session, to_link, to_link_addr,
to_link_socket_info, wakeup))
active = true;
/*
* If tls_process hits an error:
* (1) If the session has an unexpired lame duck key, preserve it.
* (2) Reinitialize the session.
* (3) Increment soft error count
*/
if (ks->state == S_ERROR)
{
++multi->n_soft_errors;
if (i == TM_ACTIVE)
error = true;
if (i == TM_ACTIVE
&& ks_lame->state >= S_ACTIVE
&& !multi->opt.single_session)
move_session (multi, TM_LAME_DUCK, TM_ACTIVE, true);
else
reset_session (multi, session);
}
}
/*mutex_cycle (multi->mutex);*/
}
update_time ();
/*
* If lame duck session expires, kill it.
*/
if (lame_duck_must_die (&multi->session[TM_LAME_DUCK], wakeup)) {
tls_session_free (&multi->session[TM_LAME_DUCK], true);
msg (D_TLS_DEBUG_LOW, "TLS: tls_multi_process: killed expiring key");
}
/*
* If untrusted session achieves TLS authentication,
* move it to active session, usurping any prior session.
*
* A semi-trusted session is one in which the certificate authentication
* succeeded (if cert verification is enabled) but the username/password
* verification failed. A semi-trusted session can forward data on the
* TLS control channel but not on the tunnel channel.
*/
if (DECRYPT_KEY_ENABLED (multi, &multi->session[TM_UNTRUSTED].key[KS_PRIMARY])) {
move_session (multi, TM_ACTIVE, TM_UNTRUSTED, true);
msg (D_TLS_DEBUG_LOW, "TLS: tls_multi_process: untrusted session promoted to %strusted",
tls_authenticated (multi) ? "" : "semi-");
}
/*
* A hard error means that TM_ACTIVE hit an S_ERROR state and that no
* other key state objects are S_ACTIVE or higher.
*/
if (error)
{
for (i = 0; i < (int) SIZE (multi->key_scan); ++i)
{
if (multi->key_scan[i]->state >= S_ACTIVE)
goto nohard;
}
++multi->n_hard_errors;
}
nohard:
#ifdef ENABLE_DEBUG
/* DEBUGGING -- flood peer with repeating connection attempts */
{
const int throw_level = GREMLIN_CONNECTION_FLOOD_LEVEL (multi->opt.gremlin);
if (throw_level)
{
for (i = 0; i < (int) SIZE (multi->key_scan); ++i)
{
if (multi->key_scan[i]->state >= throw_level)
{
++multi->n_hard_errors;
++multi->n_soft_errors;
}
}
}
}
#endif
perf_pop ();
gc_free (&gc);
return active;
}
/*
* Pre and post-process the encryption & decryption buffers in order
* to implement a multiplexed TLS channel over the TCP/UDP port.
*/
/*
*
* When we are in TLS mode, this is the first routine which sees
* an incoming packet.
*
* If it's a data packet, we set opt so that our caller can
* decrypt it. We also give our caller the appropriate decryption key.
*
* If it's a control packet, we authenticate it and process it,
* possibly creating a new tls_session if it represents the
* first packet of a new session. For control packets, we will
* also zero the size of *buf so that our caller ignores the
* packet on our return.
*
* Note that openvpn only allows one active session at a time,
* so a new session (once authenticated) will always usurp
* an old session.
*
* Return true if input was an authenticated control channel
* packet.
*
* If we are running in TLS thread mode, all public routines
* below this point must be called with the L_TLS lock held.
*/
bool
tls_pre_decrypt (struct tls_multi *multi,
struct sockaddr_in *from,
struct buffer *buf,
struct crypto_options *opt)
{
struct gc_arena gc = gc_new ();
bool ret = false;
if (buf->len > 0)
{
int i;
int op;
int key_id;
/* get opcode and key ID */
{
uint8_t c = *BPTR (buf);
op = c >> P_OPCODE_SHIFT;
key_id = c & P_KEY_ID_MASK;
}
if (op == P_DATA_V1)
{ /* data channel packet */
for (i = 0; i < KEY_SCAN_SIZE; ++i)
{
struct key_state *ks = multi->key_scan[i];
/*
* This is the basic test of TLS state compatibility between a local OpenVPN
* instance and its remote peer.
*
* If the test fails, it tells us that we are getting a packet from a source
* which claims reference to a prior negotiated TLS session, but the local
* OpenVPN instance has no memory of such a negotiation.
*
* It almost always occurs on UDP sessions when the passive side of the
* connection is restarted without the active side restarting as well (the
* passive side is the server which only listens for the connections, the
* active side is the client which initiates connections).
*/
if (DECRYPT_KEY_ENABLED (multi, ks)
&& key_id == ks->key_id
&& ks->authenticated
&& addr_port_match(from, &ks->remote_addr))
{
/* return appropriate data channel decrypt key in opt */
opt->key_ctx_bi = &ks->key;
opt->packet_id = multi->opt.replay ? &ks->packet_id : NULL;
opt->pid_persist = NULL;
opt->flags &= multi->opt.crypto_flags_and;
opt->flags |= multi->opt.crypto_flags_or;
ASSERT (buf_advance (buf, 1));
++ks->n_packets;
ks->n_bytes += buf->len;
dmsg (D_TLS_DEBUG,
"TLS: data channel, key_id=%d, IP=%s",
key_id, print_sockaddr (from, &gc));
gc_free (&gc);
return ret;
}
#if 0 /* keys out of sync? */
else
{
dmsg (D_TLS_DEBUG, "TLS_PRE_DECRYPT: [%d] dken=%d rkid=%d lkid=%d auth=%d match=%d",
i,
DECRYPT_KEY_ENABLED (multi, ks),
key_id,
ks->key_id,
ks->authenticated,
addr_port_match (from, &ks->remote_addr));
}
#endif
}
msg (D_TLS_ERRORS,
"TLS Error: local/remote TLS keys are out of sync: %s [%d]",
print_sockaddr (from, &gc), key_id);
goto error;
}
else /* control channel packet */
{
bool do_burst = false;
bool new_link = false;
struct session_id sid; /* remote session ID */
/* verify legal opcode */
if (op < P_FIRST_OPCODE || op > P_LAST_OPCODE)
{
msg (D_TLS_ERRORS,
"TLS Error: unknown opcode received from %s op=%d",
print_sockaddr (from, &gc), op);
goto error;
}
/* hard reset ? */
if (is_hard_reset (op, 0))
{
/* verify client -> server or server -> client connection */
if (((op == P_CONTROL_HARD_RESET_CLIENT_V1
|| op == P_CONTROL_HARD_RESET_CLIENT_V2) && !multi->opt.server)
|| ((op == P_CONTROL_HARD_RESET_SERVER_V1
|| op == P_CONTROL_HARD_RESET_SERVER_V2) && multi->opt.server))
{
msg (D_TLS_ERRORS,
"TLS Error: client->client or server->server connection attempted from %s",
print_sockaddr (from, &gc));
goto error;
}
}
/*
* Authenticate Packet
*/
dmsg (D_TLS_DEBUG, "TLS: control channel, op=%s, IP=%s",
packet_opcode_name (op), print_sockaddr (from, &gc));
/* get remote session-id */
{
struct buffer tmp = *buf;
buf_advance (&tmp, 1);
if (!session_id_read (&sid, &tmp) || !session_id_defined (&sid))
{
msg (D_TLS_ERRORS,
"TLS Error: session-id not found in packet from %s",
print_sockaddr (from, &gc));
goto error;
}
}
/* use session ID to match up packet with appropriate tls_session object */
for (i = 0; i < TM_SIZE; ++i)
{
struct tls_session *session = &multi->session[i];
struct key_state *ks = &session->key[KS_PRIMARY];
dmsg (D_TLS_DEBUG,
"TLS: initial packet test, i=%d state=%s, mysid=%s, rec-sid=%s, rec-ip=%s, stored-sid=%s, stored-ip=%s",
i,
state_name (ks->state),
session_id_print (&session->session_id, &gc),
session_id_print (&sid, &gc),
print_sockaddr (from, &gc),
session_id_print (&ks->session_id_remote, &gc),
print_sockaddr (&ks->remote_addr, &gc));
if (session_id_equal (&ks->session_id_remote, &sid))
/* found a match */
{
if (i == TM_LAME_DUCK) {
msg (D_TLS_ERRORS,
"TLS ERROR: received control packet with stale session-id=%s",
session_id_print (&sid, &gc));
goto error;
}
dmsg (D_TLS_DEBUG,
"TLS: found match, session[%d], sid=%s",
i, session_id_print (&sid, &gc));
break;
}
}
/*
* Initial packet received.
*/
if (i == TM_SIZE && is_hard_reset (op, 0))
{
struct tls_session *session = &multi->session[TM_ACTIVE];
struct key_state *ks = &session->key[KS_PRIMARY];
if (!is_hard_reset (op, multi->opt.key_method))
{
msg (D_TLS_ERRORS, "TLS ERROR: initial packet local/remote key_method mismatch, local key_method=%d, op=%s",
multi->opt.key_method,
packet_opcode_name (op));
goto error;
}
/*
* If we have no session currently in progress, the initial packet will
* open a new session in TM_ACTIVE rather than TM_UNTRUSTED.
*/
if (!session_id_defined (&ks->session_id_remote))
{
if (multi->opt.single_session && multi->n_sessions)
{
msg (D_TLS_ERRORS,
"TLS Error: Cannot accept new session request from %s due to --single-session [1]",
print_sockaddr (from, &gc));
goto error;
}
#ifdef ENABLE_MANAGEMENT
if (management)
{
management_set_state (management,
OPENVPN_STATE_AUTH,
NULL,
0);
}
#endif
msg (D_TLS_DEBUG_LOW,
"TLS: Initial packet from %s, sid=%s",
print_sockaddr (from, &gc),
session_id_print (&sid, &gc));
do_burst = true;
new_link = true;
i = TM_ACTIVE;
session->untrusted_sockaddr = *from;
}
}
if (i == TM_SIZE && is_hard_reset (op, 0))
{
/*
* No match with existing sessions,
* probably a new session.
*/
struct tls_session *session = &multi->session[TM_UNTRUSTED];
/*
* If --single-session, don't allow any hard-reset connection request
* unless it the the first packet of the session.
*/
if (multi->opt.single_session)
{
msg (D_TLS_ERRORS,
"TLS Error: Cannot accept new session request from %s due to --single-session [2]",
print_sockaddr (from, &gc));
goto error;
}
if (!is_hard_reset (op, multi->opt.key_method))
{
msg (D_TLS_ERRORS, "TLS ERROR: new session local/remote key_method mismatch, local key_method=%d, op=%s",
multi->opt.key_method,
packet_opcode_name (op));
goto error;
}
if (!read_control_auth (buf, &session->tls_auth, from))
goto error;
/*
* New session-initiating control packet is authenticated at this point,
* assuming that the --tls-auth command line option was used.
*
* Without --tls-auth, we leave authentication entirely up to TLS.
*/
msg (D_TLS_DEBUG_LOW,
"TLS: new session incoming connection from %s",
print_sockaddr (from, &gc));
new_link = true;
i = TM_UNTRUSTED;
session->untrusted_sockaddr = *from;
}
else
{
struct tls_session *session = &multi->session[i];
struct key_state *ks = &session->key[KS_PRIMARY];
/*
* Packet must belong to an existing session.
*/
if (i != TM_ACTIVE && i != TM_UNTRUSTED)
{
msg (D_TLS_ERRORS,
"TLS Error: Unroutable control packet received from %s (si=%d op=%s)",
print_sockaddr (from, &gc),
i,
packet_opcode_name (op));
goto error;
}
/*
* Verify remote IP address
*/
if (!new_link && !addr_port_match (&ks->remote_addr, from))
{
msg (D_TLS_ERRORS, "TLS Error: Received control packet from unexpected IP addr: %s",
print_sockaddr (from, &gc));
goto error;
}
/*
* Remote is requesting a key renegotiation
*/
if (op == P_CONTROL_SOFT_RESET_V1
&& DECRYPT_KEY_ENABLED (multi, ks))
{
if (!read_control_auth (buf, &session->tls_auth, from))
goto error;
key_state_soft_reset (session);
dmsg (D_TLS_DEBUG,
"TLS: received P_CONTROL_SOFT_RESET_V1 s=%d sid=%s",
i, session_id_print (&sid, &gc));
}
else
{
/*
* Remote responding to our key renegotiation request?
*/
if (op == P_CONTROL_SOFT_RESET_V1)
do_burst = true;
if (!read_control_auth (buf, &session->tls_auth, from))
goto error;
dmsg (D_TLS_DEBUG,
"TLS: received control channel packet s#=%d sid=%s",
i, session_id_print (&sid, &gc));
}
}
/*
* We have an authenticated packet (if --tls-auth was set).
* Now pass to our reliability level which deals with
* packet acknowledgements, retransmits, sequencing, etc.
*/
{
struct tls_session *session = &multi->session[i];
struct key_state *ks = &session->key[KS_PRIMARY];
/* Make sure we were initialized and that we're not in an error state */
ASSERT (ks->state != S_UNDEF);
ASSERT (ks->state != S_ERROR);
ASSERT (session_id_defined (&session->session_id));
/* Let our caller know we processed a control channel packet */
ret = true;
/*
* Set our remote address and remote session_id
*/
if (new_link)
{
ks->session_id_remote = sid;
ks->remote_addr = *from;
++multi->n_sessions;
}
else if (!addr_port_match (&ks->remote_addr, from))
{
msg (D_TLS_ERRORS,
"TLS Error: Existing session control channel packet from unknown IP address: %s",
print_sockaddr (from, &gc));
goto error;
}
/*
* Should we do a retransmit of all unacknowledged packets in
* the send buffer? This improves the start-up efficiency of the
* initial key negotiation after the 2nd peer comes online.
*/
if (do_burst && !session->burst)
{
reliable_schedule_now (ks->send_reliable);
session->burst = true;
}
/* Check key_id */
if (ks->key_id != key_id)
{
msg (D_TLS_ERRORS,
"TLS ERROR: local/remote key IDs out of sync (%d/%d) ID: %s",
ks->key_id, key_id, print_key_id (multi, &gc));
goto error;
}
/*
* Process incoming ACKs for packets we can now
* delete from reliable send buffer
*/
{
/* buffers all packet IDs to delete from send_reliable */
struct reliable_ack send_ack;
send_ack.len = 0;
if (!reliable_ack_read (&send_ack, buf, &session->session_id))
{
msg (D_TLS_ERRORS,
"TLS Error: reading acknowledgement record from packet");
goto error;
}
reliable_send_purge (ks->send_reliable, &send_ack);
}
if (op != P_ACK_V1 && reliable_can_get (ks->rec_reliable))
{
packet_id_type id;
/* Extract the packet ID from the packet */
if (reliable_ack_read_packet_id (buf, &id))
{
/* Avoid deadlock by rejecting packet that would de-sequentialize receive buffer */
if (reliable_wont_break_sequentiality (ks->rec_reliable, id))
{
if (reliable_not_replay (ks->rec_reliable, id))
{
/* Save incoming ciphertext packet to reliable buffer */
struct buffer *in = reliable_get_buf (ks->rec_reliable);
ASSERT (in);
ASSERT (buf_copy (in, buf));
reliable_mark_active_incoming (ks->rec_reliable, in, id, op);
}
/* Process outgoing acknowledgment for packet just received, even if it's a replay */
reliable_ack_acknowledge_packet_id (ks->rec_ack, id);
}
}
}
}
}
}
done:
buf->len = 0;
opt->key_ctx_bi = NULL;
opt->packet_id = NULL;
opt->pid_persist = NULL;
opt->flags &= multi->opt.crypto_flags_and;
gc_free (&gc);
return ret;
error:
ERR_clear_error ();
++multi->n_soft_errors;
goto done;
}
/*
* This function is similar to tls_pre_decrypt, except it is called
* when we are in server mode and receive an initial incoming
* packet. Note that we don't modify
* any state in our parameter objects. The purpose is solely to
* determine whether we should generate a client instance
* object, in which case true is returned.
*
* This function is essentially the first-line HMAC firewall
* on the UDP port listener in --mode server mode.
*/
bool
tls_pre_decrypt_lite (const struct tls_auth_standalone *tas,
const struct sockaddr_in *from,
const struct buffer *buf)
{
struct gc_arena gc = gc_new ();
bool ret = false;
if (buf->len > 0)
{
int op;
int key_id;
/* get opcode and key ID */
{
uint8_t c = *BPTR (buf);
op = c >> P_OPCODE_SHIFT;
key_id = c & P_KEY_ID_MASK;
}
/* this packet is from an as-yet untrusted source, so
scrutinize carefully */
if (op != P_CONTROL_HARD_RESET_CLIENT_V2)
{
/*
* This can occur due to bogus data or DoS packets.
*/
dmsg (D_TLS_STATE_ERRORS,
"TLS State Error: No TLS state for client %s, opcode=%d",
print_sockaddr (from, &gc),
op);
goto error;
}
if (key_id != 0)
{
dmsg (D_TLS_STATE_ERRORS,
"TLS State Error: Unknown key ID (%d) received from %s -- 0 was expected",
key_id,
print_sockaddr (from, &gc));
goto error;
}
if (buf->len > EXPANDED_SIZE_DYNAMIC (&tas->frame))
{
dmsg (D_TLS_STATE_ERRORS,
"TLS State Error: Large packet (size %d) received from %s -- a packet no larger than %d bytes was expected",
buf->len,
print_sockaddr (from, &gc),
EXPANDED_SIZE_DYNAMIC (&tas->frame));
goto error;
}
{
struct buffer newbuf = clone_buf (buf);
struct crypto_options co = tas->tls_auth_options;
bool status;
/*
* We are in read-only mode at this point with respect to TLS
* control channel state. After we build a new client instance
* object, we will process this session-initiating packet for real.
*/
co.flags |= CO_IGNORE_PACKET_ID;
/* HMAC test, if --tls-auth was specified */
status = read_control_auth (&newbuf, &co, from);
free_buf (&newbuf);
if (!status)
goto error;
/*
* At this point, if --tls-auth is being used, we know that
* the packet has passed the HMAC test, but we don't know if
* it is a replay yet. We will attempt to defeat replays
* by not advancing to the S_START state until we
* receive an ACK from our first reply to the client
* that includes an HMAC of our randomly generated 64 bit
* session ID.
*
* On the other hand if --tls-auth is not being used, we
* will proceed to begin the TLS authentication
* handshake with only cursory integrity checks having
* been performed, since we will be leaving the task
* of authentication solely up to TLS.
*/
ret = true;
}
}
gc_free (&gc);
return ret;
error:
ERR_clear_error ();
gc_free (&gc);
return ret;
}
/* Choose the key with which to encrypt a data packet */
void
tls_pre_encrypt (struct tls_multi *multi,
struct buffer *buf, struct crypto_options *opt)
{
multi->save_ks = NULL;
if (buf->len > 0)
{
int i;
for (i = 0; i < KEY_SCAN_SIZE; ++i)
{
struct key_state *ks = multi->key_scan[i];
if (ks->state >= S_ACTIVE && ks->authenticated)
{
opt->key_ctx_bi = &ks->key;
opt->packet_id = multi->opt.replay ? &ks->packet_id : NULL;
opt->pid_persist = NULL;
opt->flags &= multi->opt.crypto_flags_and;
opt->flags |= multi->opt.crypto_flags_or;
multi->save_ks = ks;
dmsg (D_TLS_DEBUG, "TLS: tls_pre_encrypt: key_id=%d", ks->key_id);
return;
}
}
{
struct gc_arena gc = gc_new ();
dmsg (D_TLS_NO_SEND_KEY, "TLS Warning: no data channel send key available: %s",
print_key_id (multi, &gc));
gc_free (&gc);
}
}
buf->len = 0;
opt->key_ctx_bi = NULL;
opt->packet_id = NULL;
opt->pid_persist = NULL;
opt->flags &= multi->opt.crypto_flags_and;
}
/* Prepend the appropriate opcode to encrypted buffer prior to TCP/UDP send */
void
tls_post_encrypt (struct tls_multi *multi, struct buffer *buf)
{
struct key_state *ks;
uint8_t *op;
ks = multi->save_ks;
multi->save_ks = NULL;
if (buf->len > 0)
{
ASSERT (ks);
ASSERT (op = buf_prepend (buf, 1));
*op = (P_DATA_V1 << P_OPCODE_SHIFT) | ks->key_id;
++ks->n_packets;
ks->n_bytes += buf->len;
}
}
/*
* Send a payload over the TLS control channel.
* Called externally.
*/
bool
tls_send_payload (struct tls_multi *multi,
const uint8_t *data,
int size)
{
struct tls_session *session;
struct key_state *ks;
bool ret = false;
ERR_clear_error ();
ASSERT (multi);
session = &multi->session[TM_ACTIVE];
ks = &session->key[KS_PRIMARY];
if (ks->state >= S_ACTIVE)
{
if (key_state_write_plaintext_const (multi, ks, data, size) == 1)
ret = true;
}
ERR_clear_error ();
return ret;
}
bool
tls_rec_payload (struct tls_multi *multi,
struct buffer *buf)
{
struct tls_session *session;
struct key_state *ks;
bool ret = false;
ERR_clear_error ();
ASSERT (multi);
session = &multi->session[TM_ACTIVE];
ks = &session->key[KS_PRIMARY];
if (ks->state >= S_ACTIVE && BLEN (&ks->plaintext_read_buf))
{
if (buf_copy (buf, &ks->plaintext_read_buf))
ret = true;
ks->plaintext_read_buf.len = 0;
}
ERR_clear_error ();
return ret;
}
/*
* Dump a human-readable rendition of an openvpn packet
* into a garbage collectable string which is returned.
*/
const char *
protocol_dump (struct buffer *buffer, unsigned int flags, struct gc_arena *gc)
{
struct buffer out = alloc_buf_gc (256, gc);
struct buffer buf = *buffer;
uint8_t c;
int op;
int key_id;
int tls_auth_hmac_size = (flags & PD_TLS_AUTH_HMAC_SIZE_MASK);
if (buf.len <= 0)
{
buf_printf (&out, "DATA UNDEF len=%d", buf.len);
goto done;
}
if (!(flags & PD_TLS))
goto print_data;
/*
* Initial byte (opcode)
*/
if (!buf_read (&buf, &c, sizeof (c)))
goto done;
op = (c >> P_OPCODE_SHIFT);
key_id = c & P_KEY_ID_MASK;
buf_printf (&out, "%s kid=%d", packet_opcode_name (op), key_id);
if (op == P_DATA_V1)
goto print_data;
/*
* Session ID
*/
{
struct session_id sid;
if (!session_id_read (&sid, &buf))
goto done;
if (flags & PD_VERBOSE)
buf_printf (&out, " sid=%s", session_id_print (&sid, gc));
}
/*
* tls-auth hmac + packet_id
*/
if (tls_auth_hmac_size)
{
struct packet_id_net pin;
uint8_t tls_auth_hmac[MAX_HMAC_KEY_LENGTH];
ASSERT (tls_auth_hmac_size <= MAX_HMAC_KEY_LENGTH);
if (!buf_read (&buf, tls_auth_hmac, tls_auth_hmac_size))
goto done;
if (flags & PD_VERBOSE)
buf_printf (&out, " tls_hmac=%s", format_hex (tls_auth_hmac, tls_auth_hmac_size, 0, gc));
if (!packet_id_read (&pin, &buf, true))
goto done;
buf_printf(&out, " pid=%s", packet_id_net_print (&pin, (flags & PD_VERBOSE), gc));
}
/*
* ACK list
*/
buf_printf (&out, " %s", reliable_ack_print(&buf, (flags & PD_VERBOSE), gc));
if (op == P_ACK_V1)
goto done;
/*
* Packet ID
*/
{
packet_id_type l;
if (!buf_read (&buf, &l, sizeof (l)))
goto done;
l = ntohpid (l);
buf_printf (&out, " pid=" packet_id_format, (packet_id_print_type)l);
}
print_data:
if (flags & PD_SHOW_DATA)
buf_printf (&out, " DATA %s", format_hex (BPTR (&buf), BLEN (&buf), 80, gc));
else
buf_printf (&out, " DATA len=%d", buf.len);
done:
return BSTR (&out);
}
#ifdef EXTRACT_X509_FIELD_TEST
void
extract_x509_field_test (void)
{
char line[8];
char field[4];
static const char field_name[] = "CN";
while (fgets (line, sizeof (line), stdin))
{
chomp (line);
extract_x509_field (line, field_name, field, sizeof (field));
printf ("CN: '%s'\n", field);
}
}
#endif
#else
static void dummy(void) {}
#endif /* USE_CRYPTO && USE_SSL*/
