/*
* 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) 2002-2010 OpenVPN Technologies, Inc. <sales@openvpn.net>
* Copyright (C) 2010 Fox Crypto B.V. <openvpn@fox-it.com>
*
* Additions for eurephia plugin done by:
* David Sommerseth <dazo@users.sourceforge.net> Copyright (C) 2008-2009
*
*
* 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
*/
/**
* @file Control Channel SSL/Data channel negotiation Module
*/
/*
* 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.
*/
#include "syshead.h"
#if defined(USE_CRYPTO) && defined(USE_SSL)
#include "error.h"
#include "common.h"
#include "integer.h"
#include "socket.h"
#include "misc.h"
#include "fdmisc.h"
#include "interval.h"
#include "perf.h"
#include "status.h"
#include "gremlin.h"
#include "pkcs11.h"
#include "list.h"
#include "base64.h"
#include "route.h"
#include "ssl.h"
#include "ssl_verify.h"
#include "ssl_backend.h"
#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
/*
* 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);
}
void
init_ssl_lib ()
{
tls_init_lib ();
crypto_init_lib ();
}
void
free_ssl_lib ()
{
crypto_uninit_lib ();
prng_uninit();
tls_free_lib();
}
/*
* 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, UP_TYPE_PRIVATE_KEY, GET_USER_PASS_MANAGEMENT|GET_USER_PASS_SENSITIVE|GET_USER_PASS_PASSWORD_ONLY);
}
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 */
#ifdef ENABLE_CLIENT_CR
static char *auth_challenge; /* GLOBAL */
#endif
void
auth_user_pass_setup (const char *auth_file, const struct static_challenge_info *sci)
{
auth_user_pass_enabled = true;
if (!auth_user_pass.defined)
{
#if AUTO_USERID
get_user_pass_auto_userid (&auth_user_pass, auth_file);
#else
# ifdef ENABLE_CLIENT_CR
if (auth_challenge) /* dynamic challenge/response */
get_user_pass_cr (&auth_user_pass,
auth_file,
UP_TYPE_AUTH,
GET_USER_PASS_MANAGEMENT|GET_USER_PASS_SENSITIVE|GET_USER_PASS_DYNAMIC_CHALLENGE,
auth_challenge);
else if (sci) /* static challenge response */
{
int flags = GET_USER_PASS_MANAGEMENT|GET_USER_PASS_SENSITIVE|GET_USER_PASS_STATIC_CHALLENGE;
if (sci->flags & SC_ECHO)
flags |= GET_USER_PASS_STATIC_CHALLENGE_ECHO;
get_user_pass_cr (&auth_user_pass,
auth_file,
UP_TYPE_AUTH,
flags,
sci->challenge_text);
}
else
# endif
get_user_pass (&auth_user_pass, auth_file, UP_TYPE_AUTH, GET_USER_PASS_MANAGEMENT|GET_USER_PASS_SENSITIVE);
#endif
}
}
/*
* Disable password caching
*/
void
ssl_set_auth_nocache (void)
{
passbuf.nocache = true;
auth_user_pass.nocache = true;
}
/*
* Set an authentication token
*/
void
ssl_set_auth_token (const char *token)
{
set_auth_token (&auth_user_pass, token);
}
/*
* Forget private key password AND auth-user-pass username/password.
*/
void
ssl_purge_auth (const bool auth_user_pass_only)
{
if (!auth_user_pass_only)
{
#ifdef USE_PKCS11
pkcs11_logout ();
#endif
purge_user_pass (&passbuf, true);
}
purge_user_pass (&auth_user_pass, true);
#ifdef ENABLE_CLIENT_CR
ssl_purge_auth_challenge();
#endif
}
#ifdef ENABLE_CLIENT_CR
void
ssl_purge_auth_challenge (void)
{
free (auth_challenge);
auth_challenge = NULL;
}
void
ssl_put_auth_challenge (const char *cr_str)
{
ssl_purge_auth_challenge();
auth_challenge = string_alloc(cr_str, NULL);
}
#endif
/*
* Initialize SSL context.
* All files are in PEM format.
*/
void
init_ssl (const struct options *options, struct tls_root_ctx *new_ctx)
{
ASSERT(NULL != new_ctx);
tls_clear_error();
if (options->tls_server)
{
tls_ctx_server_new(new_ctx);
tls_ctx_load_dh_params(new_ctx, options->dh_file, options->dh_file_inline);
}
else /* if client */
{
tls_ctx_client_new(new_ctx);
}
tls_ctx_set_options(new_ctx, options->ssl_flags);
if (options->pkcs12_file)
{
if (0 != tls_ctx_load_pkcs12(new_ctx, options->pkcs12_file,
options->pkcs12_file_inline, !options->ca_file))
goto err;
}
#ifdef ENABLE_PKCS11
else if (options->pkcs11_providers[0])
{
if (!tls_ctx_use_pkcs11 (new_ctx, options->pkcs11_id_management, options->pkcs11_id))
{
msg (M_WARN, "Cannot load certificate \"%s\" using PKCS#11 interface",
options->pkcs11_id);
goto err;
}
}
#endif
#ifdef ENABLE_CRYPTOAPI
else if (options->cryptoapi_cert)
{
tls_ctx_load_cryptoapi(new_ctx, options->cryptoapi_cert);
}
#endif
#ifdef MANAGMENT_EXTERNAL_KEY
else if ((options->management_flags & MF_EXTERNAL_KEY) && options->cert_file)
{
x509_cert_t *my_cert = NULL;
tls_ctx_load_cert_file(new_ctx, options->cert_file, options->cert_file_inline,
&my_cert);
tls_ctx_use_external_private_key(new_ctx, my_cert);
tls_ctx_free_cert_file(my_cert);
}
#endif
else
{
/* Load Certificate */
if (options->cert_file)
{
tls_ctx_load_cert_file(new_ctx, options->cert_file, options->cert_file_inline, NULL);
}
/* Load Private Key */
if (options->priv_key_file)
{
if (0 != tls_ctx_load_priv_file(new_ctx, options->priv_key_file, options->priv_key_file_inline))
goto err;
}
}
if (options->ca_file || options->ca_path)
{
tls_ctx_load_ca(new_ctx, options->ca_file, options->ca_file_inline,
options->ca_path, options->tls_server);
}
/* Load extra certificates that are part of our own certificate
chain but shouldn't be included in the verify chain */
if (options->extra_certs_file || options->extra_certs_file_inline)
{
tls_ctx_load_extra_certs(new_ctx, options->extra_certs_file, options->extra_certs_file_inline);
}
/* Allowable ciphers */
if (options->cipher_list)
{
tls_ctx_restrict_ciphers(new_ctx, options->cipher_list);
}
tls_clear_error ();
return;
err:
tls_clear_error ();
tls_ctx_free (new_ctx);
return;
}
/*
* 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_OP:
return "S_NORMAL_OP";
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;
}
/** @addtogroup control_processor
* @{ */
/** @name Functions for initialization and cleanup of key_state structures
* @{ */
/**
* Initialize a \c key_state structure.
* @ingroup control_processor
*
* This function initializes a \c key_state structure associated with a \c
* tls_session. It sets up the structure's SSL-BIO, sets the object's \c
* key_state.state to \c S_INITIAL, and sets the session ID and key ID two
* appropriate values based on the \c tls_session's internal state. It
* also initializes a new set of structures for the \link reliable
* Reliability Layer\endlink.
*
* @param session - A pointer to the \c tls_session structure
* associated with the \a ks argument.
* @param ks - A pointer to the \c key_state structure to be
* initialized. This structure should already have
* been allocated before calling this function.
*/
static void
key_state_init (struct tls_session *session, struct key_state *ks)
{
update_time ();
CLEAR (*ks);
/*
* Build TLS object that reads/writes ciphertext
* to/from memory BIOs.
*/
key_state_ssl_init(&ks->ks_ssl, &session->opt->ssl_ctx, session->opt->server,
session);
/* 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 (TLS_CHANNEL_BUF_SIZE);
ks->plaintext_write_buf = alloc_buf (TLS_CHANNEL_BUF_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,
ks->key_id ? false : session->opt->xmit_hold);
reliable_init (ks->rec_reliable, BUF_SIZE (&session->opt->frame),
FRAME_HEADROOM (&session->opt->frame), TLS_RELIABLE_N_REC_BUFFERS,
false);
reliable_set_timeout (ks->send_reliable, session->opt->packet_timeout);
/* init packet ID tracker */
packet_id_init (&ks->packet_id,
session->opt->tcp_mode,
session->opt->replay_window,
session->opt->replay_time,
"SSL", ks->key_id);
#ifdef MANAGEMENT_DEF_AUTH
ks->mda_key_id = session->opt->mda_context->mda_key_id_counter++;
#endif
}
/**
* Cleanup a \c key_state structure.
* @ingroup control_processor
*
* This function cleans up a \c key_state structure. It frees the
* associated SSL-BIO, and the structures allocated for the \link reliable
* Reliability Layer\endlink.
*
* @param ks - A pointer to the \c key_state structure to be
* cleaned up.
* @param clear - Whether the memory allocated for the \a ks object
* should be overwritten with 0s.
*/
static void
key_state_free (struct key_state *ks, bool clear)
{
ks->state = S_UNDEF;
key_state_ssl_free(&ks->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);
buffer_list_free(ks->paybuf);
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);
#ifdef PLUGIN_DEF_AUTH
key_state_rm_auth_control_file (ks);
#endif
if (clear)
CLEAR (*ks);
}
/** @} name Functions for initialization and cleanup of key_state structures */
/** @} addtogroup control_processor */
/*
* 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;
}
/** @addtogroup control_processor
* @{ */
/** @name Functions for initialization and cleanup of tls_session structures
* @{ */
/**
* Initialize a \c tls_session structure.
* @ingroup control_processor
*
* This function initializes a \c tls_session structure. This includes
* generating a random session ID, and initializing the \c KS_PRIMARY \c
* key_state in the \c tls_session.key array.
*
* @param multi - A pointer to the \c tls_multi structure
* associated with the \a session argument.
* @param session - A pointer to the \c tls_session structure to be
* initialized. This structure should already have
* been allocated before calling this function.
*/
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->tcp_mode,
session->opt->replay_window,
session->opt->replay_time,
"TLS_AUTH", session->key_id);
/* 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);
}
/**
* Clean up a \c tls_session structure.
* @ingroup control_processor
*
* This function cleans up a \c tls_session structure. This includes
* cleaning up all associated \c key_state structures.
*
* @param session - A pointer to the \c tls_session structure to be
* cleaned up.
* @param clear - Whether the memory allocated for the \a session
* object should be overwritten with 0s.
*/
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);
cert_hash_free (session->cert_hash_set);
if (clear)
CLEAR (*session);
}
/** @} name Functions for initialization and cleanup of tls_session structures */
/** @} addtogroup control_processor */
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;
}
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;
}
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
}
/*
* Cleanup a tls_multi structure and free associated memory allocations.
*/
void
tls_multi_free (struct tls_multi *multi, bool clear)
{
int i;
ASSERT (multi);
#ifdef MANAGEMENT_DEF_AUTH
man_def_auth_set_client_reason(multi, NULL);
free (multi->peer_info);
#endif
if (multi->locked_cn)
free (multi->locked_cn);
if (multi->locked_username)
free (multi->locked_username);
cert_hash_free (multi->locked_cert_hash_set);
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_ctx_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 link_socket_actual **to_link_addr,
int opcode,
int max_ack,
bool prepend_ack)
{
uint8_t *header;
struct buffer null = clear_buf ();
ASSERT (link_socket_actual_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 link_socket_actual *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_link_socket_actual (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_link_socket_actual (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");
}
/*
* Generate the hash required by for the \c tls1_PRF function.
*
* @param md_kt Message digest to use
* @param sec Secret to base the hash on
* @param sec_len Length of the secret
* @param seed Seed to hash
* @param seed_len Length of the seed
* @param out Output buffer
* @param olen Length of the output buffer
*/
void
tls1_P_hash(const md_kt_t *md_kt,
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;
hmac_ctx_t ctx;
hmac_ctx_t ctx_tmp;
uint8_t A1[MAX_HMAC_KEY_LENGTH];
unsigned int A1_len;
#ifdef ENABLE_DEBUG
const int olen_orig = olen;
const uint8_t *out_orig = out;
#endif
CLEAR(ctx);
CLEAR(ctx_tmp);
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 = md_kt_size(md_kt);
A1_len = md_kt_size(md_kt);
hmac_ctx_init(&ctx, sec, sec_len, md_kt);
hmac_ctx_init(&ctx_tmp, sec, sec_len, md_kt);
hmac_ctx_update(&ctx,seed,seed_len);
hmac_ctx_final(&ctx, A1);
n=0;
for (;;)
{
hmac_ctx_reset(&ctx);
hmac_ctx_reset(&ctx_tmp);
hmac_ctx_update(&ctx,A1,A1_len);
hmac_ctx_update(&ctx_tmp,A1,A1_len);
hmac_ctx_update(&ctx,seed,seed_len);
if (olen > chunk)
{
hmac_ctx_final(&ctx, out);
out+=chunk;
olen-=chunk;
hmac_ctx_final(&ctx_tmp, A1); /* calc the next A1 value */
}
else /* last one */
{
hmac_ctx_final(&ctx, A1);
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);
}
/*
* Use the TLS PRF function for generating data channel keys.
* This code is based on 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_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 md_kt_t *md5 = md_kt_get("MD5");
const md_kt_t *sha1 = md_kt_get("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,
OPENVPN_OP_ENCRYPT,
"Data Channel Encrypt");
init_key_ctx (&key->decrypt,
&key2.keys[1-(int)server],
key_type,
OPENVPN_OP_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;
}
static void
flush_payload_buffer (struct key_state *ks)
{
struct buffer *b;
while ((b = buffer_list_peek (ks->paybuf)))
{
key_state_write_plaintext_const (&ks->ks_ssl, b->data, b->len);
buffer_list_pop (ks->paybuf);
}
}
/* 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)
{
struct key_state *ks = &session->key[KS_PRIMARY]; /* primary key */
struct key_state *ks_lame = &session->key[KS_LAME_DUCK]; /* retiring key */
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_empty_string (struct buffer *buf)
{
if (!buf_write_u16 (buf, 0))
return false;
return true;
}
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;
}
static char *
read_string_alloc (struct buffer *buf)
{
const int len = buf_read_u16 (buf);
char *str;
if (len < 1)
return NULL;
str = (char *) malloc(len);
check_malloc_return(str);
if (!buf_read (buf, str, len))
{
free (str);
return NULL;
}
str[len-1] = '\0';
return str;
}
void
read_string_discard (struct buffer *buf)
{
char *data = read_string_alloc(buf);
if (data)
free (data);
}
/*
* 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;
struct key_state *ks = &session->key[KS_PRIMARY]; /* primary key */
struct key_state *ks_lame = &session->key[KS_LAME_DUCK]; /* retiring 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,
OPENVPN_OP_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
push_peer_info(struct buffer *buf, struct tls_session *session)
{
struct gc_arena gc = gc_new ();
bool ret = false;
#ifdef ENABLE_PUSH_PEER_INFO
if (session->opt->push_peer_info) /* write peer info */
{
struct env_set *es = session->opt->es;
struct env_item *e;
struct buffer out = alloc_buf_gc (512*3, &gc);
/* push version */
buf_printf (&out, "IV_VER=%s\n", PACKAGE_VERSION);
/* push platform */
#if defined(TARGET_LINUX)
buf_printf (&out, "IV_PLAT=linux\n");
#elif defined(TARGET_SOLARIS)
buf_printf (&out, "IV_PLAT=solaris\n");
#elif defined(TARGET_OPENBSD)
buf_printf (&out, "IV_PLAT=openbsd\n");
#elif defined(TARGET_DARWIN)
buf_printf (&out, "IV_PLAT=mac\n");
#elif defined(TARGET_NETBSD)
buf_printf (&out, "IV_PLAT=netbsd\n");
#elif defined(TARGET_FREEBSD)
buf_printf (&out, "IV_PLAT=freebsd\n");
#elif defined(WIN32)
buf_printf (&out, "IV_PLAT=win\n");
#endif
/* push mac addr */
{
struct route_gateway_info rgi;
get_default_gateway (&rgi);
if (rgi.flags & RGI_HWADDR_DEFINED)
buf_printf (&out, "IV_HWADDR=%s\n", format_hex_ex (rgi.hwaddr, 6, 0, 1, ":", &gc));
}
/* push LZO status */
#ifdef LZO_STUB
buf_printf (&out, "IV_LZO_STUB=1\n");
#endif
/* push env vars that begin with UV_ */
for (e=es->list; e != NULL; e=e->next)
{
if (e->string)
{
if (!strncmp(e->string, "UV_", 3) && buf_safe(&out, strlen(e->string)+1))
buf_printf (&out, "%s\n", e->string);
}
}
if (!write_string(buf, BSTR(&out), -1))
goto error;
}
else
#endif
{
if (!write_empty_string (buf)) /* no peer info */
goto error;
}
ret = true;
error:
gc_free (&gc);
return ret;
}
static bool
key_method_2_write (struct buffer *buf, struct tls_session *session)
{
struct key_state *ks = &session->key[KS_PRIMARY]; /* primary key */
struct key_state *ks_lame = &session->key[KS_LAME_DUCK]; /* retiring key */
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)
{
#ifdef ENABLE_CLIENT_CR
auth_user_pass_setup (NULL, session->opt->sci);
#else
auth_user_pass_setup (NULL, NULL);
#endif
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);
}
else
{
if (!write_empty_string (buf)) /* no username */
goto error;
if (!write_empty_string (buf)) /* no password */
goto error;
}
if (!push_peer_info (buf, session))
goto error;
/*
* 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;
struct key_state *ks = &session->key[KS_PRIMARY]; /* primary key */
struct key_state *ks_lame = &session->key[KS_LAME_DUCK]; /* retiring 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,
OPENVPN_OP_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 key_state *ks = &session->key[KS_PRIMARY]; /* primary key */
struct key_state *ks_lame = &session->key[KS_LAME_DUCK]; /* retiring key */
int key_method_flags;
bool username_status, password_status;
struct gc_arena gc = gc_new ();
char *options;
/* allocate temporary objects */
ALLOC_ARRAY_CLEAR_GC (options, char, TLS_OPTIONS_LEN, &gc);
ASSERT (session->opt->key_method == 2);
/* 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;
}
ks->authenticated = false;
if (verify_user_pass_enabled(session))
{
/* Perform username/password authentication */
struct user_pass *up;
ALLOC_OBJ_CLEAR_GC (up, struct user_pass, &gc);
username_status = read_string (buf, up->username, USER_PASS_LEN);
password_status = read_string (buf, up->password, USER_PASS_LEN);
if (!username_status || !password_status)
{
CLEAR (*up);
if (!(session->opt->ssl_flags & SSLF_AUTH_USER_PASS_OPTIONAL))
{
msg (D_TLS_ERRORS, "TLS Error: Auth Username/Password was not provided by peer");
goto error;
}
}
#ifdef MANAGEMENT_DEF_AUTH
/* get peer info from control channel */
free (multi->peer_info);
multi->peer_info = read_string_alloc (buf);
#endif
verify_user_pass(up, multi, session);
CLEAR (*up);
}
else
{
/* Session verification should have occurred during TLS negotiation*/
if (!session->verified)
{
msg (D_TLS_ERRORS,
"TLS Error: Certificate verification failed (key-method 2)");
goto error;
}
ks->authenticated = true;
}
/* Perform final authentication checks */
if (ks->authenticated)
{
verify_final_auth_checks(multi, session);
}
#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);
if (session->opt->ssl_flags & SSLF_OPT_VERIFY)
{
msg (D_TLS_ERRORS, "Option inconsistency warnings triggering disconnect due to --opt-verify");
ks->authenticated = false;
}
}
#endif
buf_clear (buf);
/*
* Call OPENVPN_PLUGIN_TLS_FINAL plugin if defined, for final
* veto opportunity over authentication decision.
*/
if (ks->authenticated && plugin_defined (session->opt->plugins, OPENVPN_PLUGIN_TLS_FINAL))
{
if (plugin_call (session->opt->plugins, OPENVPN_PLUGIN_TLS_FINAL, NULL, NULL, session->opt->es) != OPENVPN_PLUGIN_FUNC_SUCCESS)
ks->authenticated = false;
}
/*
* 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;
}
static int
auth_deferred_expire_window (const struct tls_options *o)
{
int ret = o->handshake_window;
const int r2 = o->renegotiate_seconds / 2;
if (o->renegotiate_seconds && r2 < ret)
ret = r2;
return ret;
}
/*
* 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 link_socket_actual **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;
struct key_state *ks = &session->key[KS_PRIMARY]; /* primary key */
struct key_state *ks_lame = &session->key[KS_LAME_DUCK]; /* retiring key */
/* 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=" counter_format "/%d pkts=" counter_format "/%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");
}
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;
ks->auth_deferred_expire = now + auth_deferred_expire_window (session->opt);
/* 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,
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_OP");
ks->state = S_NORMAL_OP;
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->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);
/* Flush any payload packets that were buffered before our state transitioned to S_ACTIVE */
flush_payload_buffer (ks);
#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 (&ks->ks_ssl, 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 (&ks->ks_ssl, buf, TLS_CHANNEL_BUF_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 (&ks->ks_ssl, 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 (&ks->ks_ssl, 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");
}
}
}
}
}
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:
tls_clear_error();
ks->state = S_ERROR;
msg (D_TLS_ERRORS, "TLS Error: TLS handshake failed");
INCR_ERROR;
gc_free (&gc);
return false;
}
/*
* Called by the top-level event loop.
*
* Basically decides if we should call tls_process for
* the active or untrusted sessions.
*/
int
tls_multi_process (struct tls_multi *multi,
struct buffer *to_link,
struct link_socket_actual **to_link_addr,
struct link_socket_info *to_link_socket_info,
interval_t *wakeup)
{
struct gc_arena gc = gc_new ();
int i;
int active = TLSMP_INACTIVE;
bool error = false;
int tas;
perf_push (PERF_TLS_MULTI_PROCESS);
tls_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 &&
link_socket_actual_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_link_socket_actual (&ks->remote_addr, &gc));
if (ks->state >= S_INITIAL && link_socket_actual_defined (&ks->remote_addr))
{
struct link_socket_actual *tla = NULL;
update_time ();
if (tls_process (multi, session, to_link, &tla,
to_link_socket_info, wakeup))
active = TLSMP_ACTIVE;
/*
* If tls_process produced an outgoing packet,
* return the link_socket_actual object (which
* contains the outgoing address).
*/
if (tla)
{
multi->to_link_addr = *tla;
*to_link_addr = &multi->to_link_addr;
}
/*
* 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);
}
}
}
update_time ();
tas = tls_authentication_status (multi, TLS_MULTI_AUTH_STATUS_INTERVAL);
/*
* 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",
tas == TLS_AUTHENTICATION_SUCCEEDED ? "" : "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 (tas == TLS_AUTHENTICATION_FAILED) ? TLSMP_KILL : 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,
const struct link_socket_actual *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
#ifdef ENABLE_DEF_AUTH
&& !ks->auth_deferred
#endif
&& link_socket_actual_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_KEYSELECT,
"TLS: tls_pre_decrypt, key_id=%d, IP=%s",
key_id, print_link_socket_actual (from, &gc));
gc_free (&gc);
return ret;
}
#if 0 /* keys out of sync? */
else
{
dmsg (D_TLS_ERRORS, "TLS_PRE_DECRYPT: [%d] dken=%d rkid=%d lkid=%d auth=%d def=%d match=%d",
i,
DECRYPT_KEY_ENABLED (multi, ks),
key_id,
ks->key_id,
ks->authenticated,
#ifdef ENABLE_DEF_AUTH
ks->auth_deferred,
#else
-1,
#endif
link_socket_actual_match (from, &ks->remote_addr));
}
#endif
}
msg (D_TLS_ERRORS,
"TLS Error: local/remote TLS keys are out of sync: %s [%d]",
print_link_socket_actual (from, &gc), key_id);
goto error_lite;
}
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_link_socket_actual (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_link_socket_actual (from, &gc));
goto error;
}
}
/*
* Authenticate Packet
*/
dmsg (D_TLS_DEBUG, "TLS: control channel, op=%s, IP=%s",
packet_opcode_name (op), print_link_socket_actual (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_link_socket_actual (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_link_socket_actual (from, &gc),
session_id_print (&ks->session_id_remote, &gc),
print_link_socket_actual (&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 session context expire or --single-session [1]",
print_link_socket_actual (from, &gc));
goto error;
}
#ifdef ENABLE_MANAGEMENT
if (management)
{
management_set_state (management,
OPENVPN_STATE_AUTH,
NULL,
0,
0);
}
#endif
msg (D_TLS_DEBUG_LOW,
"TLS: Initial packet from %s, sid=%s",
print_link_socket_actual (from, &gc),
session_id_print (&sid, &gc));
do_burst = true;
new_link = true;
i = TM_ACTIVE;
session->untrusted_addr = *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 session context expire or --single-session [2]",
print_link_socket_actual (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_link_socket_actual (from, &gc));
new_link = true;
i = TM_UNTRUSTED;
session->untrusted_addr = *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_link_socket_actual (from, &gc),
i,
packet_opcode_name (op));
goto error;
}
/*
* Verify remote IP address
*/
if (!new_link && !link_socket_actual_match (&ks->remote_addr, from))
{
msg (D_TLS_ERRORS, "TLS Error: Received control packet from unexpected IP addr: %s",
print_link_socket_actual (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 (!link_socket_actual_match (&ks->remote_addr, from))
{
msg (D_TLS_ERRORS,
"TLS Error: Existing session control channel packet from unknown IP address: %s",
print_link_socket_actual (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:
++multi->n_soft_errors;
error_lite:
tls_clear_error();
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 link_socket_actual *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_link_socket_actual (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_link_socket_actual (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_link_socket_actual (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:
tls_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;
struct key_state *ks_select = NULL;
for (i = 0; i < KEY_SCAN_SIZE; ++i)
{
struct key_state *ks = multi->key_scan[i];
if (ks->state >= S_ACTIVE
&& ks->authenticated
#ifdef ENABLE_DEF_AUTH
&& !ks->auth_deferred
#endif
)
{
if (!ks_select)
ks_select = ks;
if (now >= ks->auth_deferred_expire)
{
ks_select = ks;
break;
}
}
}
if (ks_select)
{
opt->key_ctx_bi = &ks_select->key;
opt->packet_id = multi->opt.replay ? &ks_select->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_select;
dmsg (D_TLS_KEYSELECT, "TLS: tls_pre_encrypt: key_id=%d", ks_select->key_id);
return;
}
else
{
struct gc_arena gc = gc_new ();
dmsg (D_TLS_KEYSELECT, "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;
tls_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 (&ks->ks_ssl, data, size) == 1)
ret = true;
}
else
{
if (!ks->paybuf)
ks->paybuf = buffer_list_new (0);
buffer_list_push_data (ks->paybuf, data, (size_t)size);
ret = true;
}
tls_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;
tls_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;
}
tls_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);
}
#else
static void dummy(void) {}
#endif /* USE_CRYPTO && USE_SSL*/