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88c4b425bd
tor/src/or/command.c
Nick Mathewson 88c4b425bd Fix bug 4367: correctly detect auth_challenge cells we can't use 
Found by frosty_un, bugfix on 0.2.3.6-alpha, fix suggested by arma.
2011-11-03 11:52:35 -04:00

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/* Copyright (c) 2001 Matej Pfajfar.
* Copyright (c) 2001-2004, Roger Dingledine.
* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
* Copyright (c) 2007-2011, The Tor Project, Inc. */
/* See LICENSE for licensing information */
/**
* \file command.c
* \brief Functions for processing incoming cells.
**/
/* In-points to command.c:
*
* - command_process_cell(), called from
* connection_or_process_cells_from_inbuf() in connection_or.c
*/
#include "or.h"
#include "circuitbuild.h"
#include "circuitlist.h"
#include "command.h"
#include "connection.h"
#include "connection_or.h"
#include "config.h"
#include "control.h"
#include "cpuworker.h"
#include "hibernate.h"
#include "nodelist.h"
#include "onion.h"
#include "relay.h"
#include "router.h"
#include "routerlist.h"
/** How many CELL_PADDING cells have we received, ever? */
uint64_t stats_n_padding_cells_processed = 0;
/** How many CELL_CREATE cells have we received, ever? */
uint64_t stats_n_create_cells_processed = 0;
/** How many CELL_CREATED cells have we received, ever? */
uint64_t stats_n_created_cells_processed = 0;
/** How many CELL_RELAY cells have we received, ever? */
uint64_t stats_n_relay_cells_processed = 0;
/** How many CELL_DESTROY cells have we received, ever? */
uint64_t stats_n_destroy_cells_processed = 0;
/** How many CELL_VERSIONS cells have we received, ever? */
uint64_t stats_n_versions_cells_processed = 0;
/** How many CELL_NETINFO cells have we received, ever? */
uint64_t stats_n_netinfo_cells_processed = 0;
/** How many CELL_VPADDING cells have we received, ever? */
uint64_t stats_n_vpadding_cells_processed = 0;
/** How many CELL_CERTS cells have we received, ever? */
uint64_t stats_n_cert_cells_processed = 0;
/** How many CELL_AUTH_CHALLENGE cells have we received, ever? */
uint64_t stats_n_auth_challenge_cells_processed = 0;
/** How many CELL_AUTHENTICATE cells have we received, ever? */
uint64_t stats_n_authenticate_cells_processed = 0;
/* These are the main functions for processing cells */
static void command_process_create_cell(cell_t *cell, or_connection_t *conn);
static void command_process_created_cell(cell_t *cell, or_connection_t *conn);
static void command_process_relay_cell(cell_t *cell, or_connection_t *conn);
static void command_process_destroy_cell(cell_t *cell, or_connection_t *conn);
static void command_process_versions_cell(var_cell_t *cell,
or_connection_t *conn);
static void command_process_netinfo_cell(cell_t *cell, or_connection_t *conn);
static void command_process_cert_cell(var_cell_t *cell,
or_connection_t *conn);
static void command_process_auth_challenge_cell(var_cell_t *cell,
or_connection_t *conn);
static void command_process_authenticate_cell(var_cell_t *cell,
or_connection_t *conn);
#ifdef KEEP_TIMING_STATS
/** This is a wrapper function around the actual function that processes the
* <b>cell</b> that just arrived on <b>conn</b>. Increment <b>*time</b>
* by the number of microseconds used by the call to <b>*func(cell, conn)</b>.
*/
static void
command_time_process_cell(cell_t *cell, or_connection_t *conn, int *time,
void (*func)(cell_t *, or_connection_t *))
{
struct timeval start, end;
long time_passed;
tor_gettimeofday(&start);
(*func)(cell, conn);
tor_gettimeofday(&end);
time_passed = tv_udiff(&start, &end) ;
if (time_passed > 10000) { /* more than 10ms */
log_debug(LD_OR,"That call just took %ld ms.",time_passed/1000);
}
if (time_passed < 0) {
log_info(LD_GENERAL,"That call took us back in time!");
time_passed = 0;
}
*time += time_passed;
}
#endif
/** Process a <b>cell</b> that was just received on <b>conn</b>. Keep internal
* statistics about how many of each cell we've processed so far
* this second, and the total number of microseconds it took to
* process each type of cell.
*/
void
command_process_cell(cell_t *cell, or_connection_t *conn)
{
int handshaking = (conn->_base.state != OR_CONN_STATE_OPEN);
#ifdef KEEP_TIMING_STATS
/* how many of each cell have we seen so far this second? needs better
* name. */
static int num_create=0, num_created=0, num_relay=0, num_destroy=0;
/* how long has it taken to process each type of cell? */
static int create_time=0, created_time=0, relay_time=0, destroy_time=0;
static time_t current_second = 0; /* from previous calls to time */
time_t now = time(NULL);
if (now > current_second) { /* the second has rolled over */
/* print stats */
log_info(LD_OR,
"At end of second: %d creates (%d ms), %d createds (%d ms), "
"%d relays (%d ms), %d destroys (%d ms)",
num_create, create_time/1000,
num_created, created_time/1000,
num_relay, relay_time/1000,
num_destroy, destroy_time/1000);
/* zero out stats */
num_create = num_created = num_relay = num_destroy = 0;
create_time = created_time = relay_time = destroy_time = 0;
/* remember which second it is, for next time */
current_second = now;
}
#endif
#ifdef KEEP_TIMING_STATS
#define PROCESS_CELL(tp, cl, cn) STMT_BEGIN { \
++num ## tp; \
command_time_process_cell(cl, cn, & tp ## time , \
command_process_ ## tp ## _cell); \
} STMT_END
#else
#define PROCESS_CELL(tp, cl, cn) command_process_ ## tp ## _cell(cl, cn)
#endif
if (conn->_base.marked_for_close)
return;
/* Reject all but VERSIONS and NETINFO when handshaking. */
/* (VERSIONS should actually be impossible; it's variable-length.) */
if (handshaking && cell->command != CELL_VERSIONS &&
cell->command != CELL_NETINFO) {
log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
"Received unexpected cell command %d in state %s; ignoring it.",
(int)cell->command,
conn_state_to_string(CONN_TYPE_OR,conn->_base.state));
return;
}
if (conn->_base.state == OR_CONN_STATE_OR_HANDSHAKING_V3)
or_handshake_state_record_cell(conn->handshake_state, cell, 1);
switch (cell->command) {
case CELL_PADDING:
++stats_n_padding_cells_processed;
/* do nothing */
break;
case CELL_CREATE:
case CELL_CREATE_FAST:
++stats_n_create_cells_processed;
PROCESS_CELL(create, cell, conn);
break;
case CELL_CREATED:
case CELL_CREATED_FAST:
++stats_n_created_cells_processed;
PROCESS_CELL(created, cell, conn);
break;
case CELL_RELAY:
case CELL_RELAY_EARLY:
++stats_n_relay_cells_processed;
PROCESS_CELL(relay, cell, conn);
break;
case CELL_DESTROY:
++stats_n_destroy_cells_processed;
PROCESS_CELL(destroy, cell, conn);
break;
case CELL_VERSIONS:
tor_fragile_assert();
break;
case CELL_NETINFO:
++stats_n_netinfo_cells_processed;
PROCESS_CELL(netinfo, cell, conn);
break;
default:
log_fn(LOG_INFO, LD_PROTOCOL,
"Cell of unknown type (%d) received. Dropping.", cell->command);
break;
}
}
/** Process a <b>cell</b> that was just received on <b>conn</b>. Keep internal
* statistics about how many of each cell we've processed so far
* this second, and the total number of microseconds it took to
* process each type of cell.
*/
void
command_process_var_cell(var_cell_t *cell, or_connection_t *conn)
{
#ifdef KEEP_TIMING_STATS
/* how many of each cell have we seen so far this second? needs better
* name. */
static int num_versions=0, num_cert=0;
time_t now = time(NULL);
if (now > current_second) { /* the second has rolled over */
/* print stats */
log_info(LD_OR,
"At end of second: %d versions (%d ms), %d cert (%d ms)",
num_versions, versions_time/1000,
cert, cert_time/1000);
num_versions = num_cert = 0;
versions_time = cert_time = 0;
/* remember which second it is, for next time */
current_second = now;
}
#endif
if (conn->_base.marked_for_close)
return;
switch (conn->_base.state)
{
case OR_CONN_STATE_OR_HANDSHAKING_V2:
if (cell->command != CELL_VERSIONS)
return;
break;
case OR_CONN_STATE_TLS_HANDSHAKING:
/* If we're using bufferevents, it's entirely possible for us to
* notice "hey, data arrived!" before we notice "hey, the handshake
* finished!" And we need to be accepting both at once to handle both
* the v2 and v3 handshakes. */
/* fall through */
case OR_CONN_STATE_TLS_SERVER_RENEGOTIATING:
if (cell->command != CELL_VERSIONS) {
log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
"Received a non-VERSIONS cell with command %d in state %s; "
"ignoring it.",
(int)cell->command,
conn_state_to_string(CONN_TYPE_OR,conn->_base.state));
return;
}
break;
case OR_CONN_STATE_OR_HANDSHAKING_V3:
if (cell->command != CELL_AUTHENTICATE)
or_handshake_state_record_var_cell(conn->handshake_state, cell, 1);
break; /* Everything is allowed */
case OR_CONN_STATE_OPEN:
if (conn->link_proto < 3) {
log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
"Received a variable-length cell with command %d in state %s "
"with link protocol %d; ignoring it.",
(int)cell->command,
conn_state_to_string(CONN_TYPE_OR,conn->_base.state),
(int)conn->link_proto);
return;
}
break;
default:
log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
"Received var-length cell with command %d in unexpected state "
"%s [%d]; ignoring it.",
(int)cell->command,
conn_state_to_string(CONN_TYPE_OR,conn->_base.state),
(int)conn->_base.state);
return;
}
switch (cell->command) {
case CELL_VERSIONS:
++stats_n_versions_cells_processed;
PROCESS_CELL(versions, cell, conn);
break;
case CELL_VPADDING:
++stats_n_vpadding_cells_processed;
/* Do nothing */
break;
case CELL_CERT:
++stats_n_cert_cells_processed;
PROCESS_CELL(cert, cell, conn);
break;
case CELL_AUTH_CHALLENGE:
++stats_n_auth_challenge_cells_processed;
PROCESS_CELL(auth_challenge, cell, conn);
break;
case CELL_AUTHENTICATE:
++stats_n_authenticate_cells_processed;
PROCESS_CELL(authenticate, cell, conn);
break;
default:
log_fn(LOG_INFO, LD_PROTOCOL,
"Variable-length cell of unknown type (%d) received.",
cell->command);
break;
}
}
/** Process a 'create' <b>cell</b> that just arrived from <b>conn</b>. Make a
* new circuit with the p_circ_id specified in cell. Put the circuit in state
* onionskin_pending, and pass the onionskin to the cpuworker. Circ will get
* picked up again when the cpuworker finishes decrypting it.
*/
static void
command_process_create_cell(cell_t *cell, or_connection_t *conn)
{
or_circuit_t *circ;
const or_options_t *options = get_options();
int id_is_high;
if (we_are_hibernating()) {
log_info(LD_OR,
"Received create cell but we're shutting down. Sending back "
"destroy.");
connection_or_send_destroy(cell->circ_id, conn,
END_CIRC_REASON_HIBERNATING);
return;
}
if (!server_mode(options) ||
(!public_server_mode(options) && conn->is_outgoing)) {
log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
"Received create cell (type %d) from %s:%d, but we're connected "
"to it as a client. "
"Sending back a destroy.",
(int)cell->command, conn->_base.address, conn->_base.port);
connection_or_send_destroy(cell->circ_id, conn,
END_CIRC_REASON_TORPROTOCOL);
return;
}
/* If the high bit of the circuit ID is not as expected, close the
* circ. */
id_is_high = cell->circ_id & (1<<15);
if ((id_is_high && conn->circ_id_type == CIRC_ID_TYPE_HIGHER) ||
(!id_is_high && conn->circ_id_type == CIRC_ID_TYPE_LOWER)) {
log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
"Received create cell with unexpected circ_id %d. Closing.",
cell->circ_id);
connection_or_send_destroy(cell->circ_id, conn,
END_CIRC_REASON_TORPROTOCOL);
return;
}
if (circuit_id_in_use_on_orconn(cell->circ_id, conn)) {
const node_t *node = node_get_by_id(conn->identity_digest);
log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
"Received CREATE cell (circID %d) for known circ. "
"Dropping (age %d).",
cell->circ_id, (int)(time(NULL) - conn->_base.timestamp_created));
if (node) {
char *p = esc_for_log(node_get_platform(node));
log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
"Details: router %s, platform %s.",
node_describe(node), p);
tor_free(p);
}
return;
}
circ = or_circuit_new(cell->circ_id, conn);
circ->_base.purpose = CIRCUIT_PURPOSE_OR;
circuit_set_state(TO_CIRCUIT(circ), CIRCUIT_STATE_ONIONSKIN_PENDING);
if (cell->command == CELL_CREATE) {
char *onionskin = tor_malloc(ONIONSKIN_CHALLENGE_LEN);
memcpy(onionskin, cell->payload, ONIONSKIN_CHALLENGE_LEN);
/* hand it off to the cpuworkers, and then return. */
if (assign_onionskin_to_cpuworker(NULL, circ, onionskin) < 0) {
#define WARN_HANDOFF_FAILURE_INTERVAL (6*60*60)
static ratelim_t handoff_warning =
RATELIM_INIT(WARN_HANDOFF_FAILURE_INTERVAL);
char *m;
if ((m = rate_limit_log(&handoff_warning, approx_time()))) {
log_warn(LD_GENERAL,"Failed to hand off onionskin. Closing.%s",m);
tor_free(m);
}
circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_INTERNAL);
return;
}
log_debug(LD_OR,"success: handed off onionskin.");
} else {
/* This is a CREATE_FAST cell; we can handle it immediately without using
* a CPU worker. */
char keys[CPATH_KEY_MATERIAL_LEN];
char reply[DIGEST_LEN*2];
tor_assert(cell->command == CELL_CREATE_FAST);
/* Make sure we never try to use the OR connection on which we
* received this cell to satisfy an EXTEND request, */
conn->is_connection_with_client = 1;
if (fast_server_handshake(cell->payload, (uint8_t*)reply,
(uint8_t*)keys, sizeof(keys))<0) {
log_warn(LD_OR,"Failed to generate key material. Closing.");
circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_INTERNAL);
return;
}
if (onionskin_answer(circ, CELL_CREATED_FAST, reply, keys)<0) {
log_warn(LD_OR,"Failed to reply to CREATE_FAST cell. Closing.");
circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_INTERNAL);
return;
}
}
}
/** Process a 'created' <b>cell</b> that just arrived from <b>conn</b>.
* Find the circuit
* that it's intended for. If we're not the origin of the circuit, package
* the 'created' cell in an 'extended' relay cell and pass it back. If we
* are the origin of the circuit, send it to circuit_finish_handshake() to
* finish processing keys, and then call circuit_send_next_onion_skin() to
* extend to the next hop in the circuit if necessary.
*/
static void
command_process_created_cell(cell_t *cell, or_connection_t *conn)
{
circuit_t *circ;
circ = circuit_get_by_circid_orconn(cell->circ_id, conn);
if (!circ) {
log_info(LD_OR,
"(circID %d) unknown circ (probably got a destroy earlier). "
"Dropping.", cell->circ_id);
return;
}
if (circ->n_circ_id != cell->circ_id) {
log_fn(LOG_PROTOCOL_WARN,LD_PROTOCOL,
"got created cell from Tor client? Closing.");
circuit_mark_for_close(circ, END_CIRC_REASON_TORPROTOCOL);
return;
}
if (CIRCUIT_IS_ORIGIN(circ)) { /* we're the OP. Handshake this. */
origin_circuit_t *origin_circ = TO_ORIGIN_CIRCUIT(circ);
int err_reason = 0;
log_debug(LD_OR,"at OP. Finishing handshake.");
if ((err_reason = circuit_finish_handshake(origin_circ, cell->command,
cell->payload)) < 0) {
log_warn(LD_OR,"circuit_finish_handshake failed.");
circuit_mark_for_close(circ, -err_reason);
return;
}
log_debug(LD_OR,"Moving to next skin.");
if ((err_reason = circuit_send_next_onion_skin(origin_circ)) < 0) {
log_info(LD_OR,"circuit_send_next_onion_skin failed.");
/* XXX push this circuit_close lower */
circuit_mark_for_close(circ, -err_reason);
return;
}
} else { /* pack it into an extended relay cell, and send it. */
log_debug(LD_OR,
"Converting created cell to extended relay cell, sending.");
relay_send_command_from_edge(0, circ, RELAY_COMMAND_EXTENDED,
(char*)cell->payload, ONIONSKIN_REPLY_LEN,
NULL);
}
}
/** Process a 'relay' or 'relay_early' <b>cell</b> that just arrived from
* <b>conn</b>. Make sure it came in with a recognized circ_id. Pass it on to
* circuit_receive_relay_cell() for actual processing.
*/
static void
command_process_relay_cell(cell_t *cell, or_connection_t *conn)
{
circuit_t *circ;
int reason, direction;
circ = circuit_get_by_circid_orconn(cell->circ_id, conn);
if (!circ) {
log_debug(LD_OR,
"unknown circuit %d on connection from %s:%d. Dropping.",
cell->circ_id, conn->_base.address, conn->_base.port);
return;
}
if (circ->state == CIRCUIT_STATE_ONIONSKIN_PENDING) {
log_fn(LOG_PROTOCOL_WARN,LD_PROTOCOL,"circuit in create_wait. Closing.");
circuit_mark_for_close(circ, END_CIRC_REASON_TORPROTOCOL);
return;
}
if (CIRCUIT_IS_ORIGIN(circ)) {
/* if we're a relay and treating connections with recent local
* traffic better, then this is one of them. */
conn->client_used = time(NULL);
}
if (!CIRCUIT_IS_ORIGIN(circ) &&
cell->circ_id == TO_OR_CIRCUIT(circ)->p_circ_id)
direction = CELL_DIRECTION_OUT;
else
direction = CELL_DIRECTION_IN;
/* If we have a relay_early cell, make sure that it's outbound, and we've
* gotten no more than MAX_RELAY_EARLY_CELLS_PER_CIRCUIT of them. */
if (cell->command == CELL_RELAY_EARLY) {
if (direction == CELL_DIRECTION_IN) {
/* Allow an unlimited number of inbound relay_early cells,
* for hidden service compatibility. There isn't any way to make
* a long circuit through inbound relay_early cells anyway. See
* bug 1038. -RD */
} else {
or_circuit_t *or_circ = TO_OR_CIRCUIT(circ);
if (or_circ->remaining_relay_early_cells == 0) {
log_fn(LOG_PROTOCOL_WARN, LD_OR,
"Received too many RELAY_EARLY cells on circ %d from %s:%d."
" Closing circuit.",
cell->circ_id, safe_str(conn->_base.address),
conn->_base.port);
circuit_mark_for_close(circ, END_CIRC_REASON_TORPROTOCOL);
return;
}
--or_circ->remaining_relay_early_cells;
}
}
if ((reason = circuit_receive_relay_cell(cell, circ, direction)) < 0) {
log_fn(LOG_PROTOCOL_WARN,LD_PROTOCOL,"circuit_receive_relay_cell "
"(%s) failed. Closing.",
direction==CELL_DIRECTION_OUT?"forward":"backward");
circuit_mark_for_close(circ, -reason);
}
}
/** Process a 'destroy' <b>cell</b> that just arrived from
* <b>conn</b>. Find the circ that it refers to (if any).
*
* If the circ is in state
* onionskin_pending, then call onion_pending_remove() to remove it
* from the pending onion list (note that if it's already being
* processed by the cpuworker, it won't be in the list anymore; but
* when the cpuworker returns it, the circuit will be gone, and the
* cpuworker response will be dropped).
*
* Then mark the circuit for close (which marks all edges for close,
* and passes the destroy cell onward if necessary).
*/
static void
command_process_destroy_cell(cell_t *cell, or_connection_t *conn)
{
circuit_t *circ;
int reason;
circ = circuit_get_by_circid_orconn(cell->circ_id, conn);
reason = (uint8_t)cell->payload[0];
if (!circ) {
log_info(LD_OR,"unknown circuit %d on connection from %s:%d. Dropping.",
cell->circ_id, conn->_base.address, conn->_base.port);
return;
}
log_debug(LD_OR,"Received for circID %d.",cell->circ_id);
if (!CIRCUIT_IS_ORIGIN(circ) &&
cell->circ_id == TO_OR_CIRCUIT(circ)->p_circ_id) {
/* the destroy came from behind */
circuit_set_p_circid_orconn(TO_OR_CIRCUIT(circ), 0, NULL);
circuit_mark_for_close(circ, reason|END_CIRC_REASON_FLAG_REMOTE);
} else { /* the destroy came from ahead */
circuit_set_n_circid_orconn(circ, 0, NULL);
if (CIRCUIT_IS_ORIGIN(circ)) {
circuit_mark_for_close(circ, reason|END_CIRC_REASON_FLAG_REMOTE);
} else {
char payload[1];
log_debug(LD_OR, "Delivering 'truncated' back.");
payload[0] = (char)reason;
relay_send_command_from_edge(0, circ, RELAY_COMMAND_TRUNCATED,
payload, sizeof(payload), NULL);
}
}
}
/** Process a 'versions' cell. The current link protocol version must be 0
* to indicate that no version has yet been negotiated. We compare the
* versions in the cell to the list of versions we support, pick the
* highest version we have in common, and continue the negotiation from
* there.
*/
static void
command_process_versions_cell(var_cell_t *cell, or_connection_t *conn)
{
int highest_supported_version = 0;
const uint8_t *cp, *end;
const int started_here = connection_or_nonopen_was_started_here(conn);
if (conn->link_proto != 0 ||
(conn->handshake_state && conn->handshake_state->received_versions)) {
log_fn(LOG_PROTOCOL_WARN, LD_OR,
"Received a VERSIONS cell on a connection with its version "
"already set to %d; dropping", (int) conn->link_proto);
return;
}
switch (conn->_base.state)
{
case OR_CONN_STATE_OR_HANDSHAKING_V2:
break;
case OR_CONN_STATE_TLS_HANDSHAKING:
case OR_CONN_STATE_TLS_SERVER_RENEGOTIATING:
if (started_here) {
log_fn(LOG_PROTOCOL_WARN, LD_OR,
"Received a versions cell while TLS-handshaking not in "
"OR_HANDSHAKING_V3 on a connection we originated.");
}
conn->_base.state = OR_CONN_STATE_OR_HANDSHAKING_V3;
if (connection_init_or_handshake_state(conn, started_here) < 0) {
connection_mark_for_close(TO_CONN(conn));
return;
}
or_handshake_state_record_var_cell(conn->handshake_state, cell, 1);
break;
case OR_CONN_STATE_OR_HANDSHAKING_V3:
break;
default:
log_fn(LOG_PROTOCOL_WARN, LD_OR,
"VERSIONS cell while in unexpected state");
return;
}
tor_assert(conn->handshake_state);
end = cell->payload + cell->payload_len;
for (cp = cell->payload; cp+1 < end; ++cp) {
uint16_t v = ntohs(get_uint16(cp));
if (is_or_protocol_version_known(v) && v > highest_supported_version)
highest_supported_version = v;
}
if (!highest_supported_version) {
log_fn(LOG_PROTOCOL_WARN, LD_OR,
"Couldn't find a version in common between my version list and the "
"list in the VERSIONS cell; closing connection.");
connection_mark_for_close(TO_CONN(conn));
return;
} else if (highest_supported_version == 1) {
/* Negotiating version 1 makes no sense, since version 1 has no VERSIONS
* cells. */
log_fn(LOG_PROTOCOL_WARN, LD_OR,
"Used version negotiation protocol to negotiate a v1 connection. "
"That's crazily non-compliant. Closing connection.");
connection_mark_for_close(TO_CONN(conn));
return;
} else if (highest_supported_version < 3 &&
conn->_base.state == OR_CONN_STATE_OR_HANDSHAKING_V3) {
log_fn(LOG_PROTOCOL_WARN, LD_OR,
"Negotiated link protocol 2 or lower after doing a v3 TLS "
"handshake. Closing connection.");
connection_mark_for_close(TO_CONN(conn));
return;
}
conn->link_proto = highest_supported_version;
conn->handshake_state->received_versions = 1;
if (conn->link_proto == 2) {
log_info(LD_OR, "Negotiated version %d with %s:%d; sending NETINFO.",
highest_supported_version,
safe_str_client(conn->_base.address),
conn->_base.port);
if (connection_or_send_netinfo(conn) < 0) {
connection_mark_for_close(TO_CONN(conn));
return;
}
} else {
const int send_versions = !started_here;
/* If we want to authenticate, send a CERTS cell */
const int send_certs = !started_here || public_server_mode(get_options());
/* If we're a relay that got a connection, ask for authentication. */
const int send_chall = !started_here && public_server_mode(get_options());
/* If our certs cell will authenticate us, or if we have no intention of
* authenticating, send a netinfo cell right now. */
const int send_netinfo =
!(started_here && public_server_mode(get_options()));
const int send_any =
send_versions || send_certs || send_chall || send_netinfo;
tor_assert(conn->link_proto >= 3);
log_info(LD_OR, "Negotiated version %d with %s:%d; %s%s%s%s%s",
highest_supported_version,
safe_str_client(conn->_base.address),
conn->_base.port,
send_any ? "Sending cells:" : "Waiting for CERTS cell",
send_versions ? " VERSIONS" : "",
send_certs ? " CERTS" : "",
send_chall ? " AUTH_CHALLENGE" : "",
send_netinfo ? " NETINFO" : "");
#ifdef DISABLE_V3_LINKPROTO_SERVERSIDE
if (1) {
connection_mark_for_close(TO_CONN(conn));
return;
}
#endif
if (send_versions) {
if (connection_or_send_versions(conn, 1) < 0) {
log_warn(LD_OR, "Couldn't send versions cell");
connection_mark_for_close(TO_CONN(conn));
return;
}
}
if (send_certs) {
if (connection_or_send_cert_cell(conn) < 0) {
log_warn(LD_OR, "Couldn't send cert cell");
connection_mark_for_close(TO_CONN(conn));
return;
}
}
if (send_chall) {
if (connection_or_send_auth_challenge_cell(conn) < 0) {
log_warn(LD_OR, "Couldn't send auth_challenge cell");
connection_mark_for_close(TO_CONN(conn));
return;
}
}
if (send_netinfo) {
if (connection_or_send_netinfo(conn) < 0) {
log_warn(LD_OR, "Couldn't send netinfo cell");
connection_mark_for_close(TO_CONN(conn));
return;
}
}
}
}
/** Process a 'netinfo' cell: read and act on its contents, and set the
* connection state to "open". */
static void
command_process_netinfo_cell(cell_t *cell, or_connection_t *conn)
{
time_t timestamp;
uint8_t my_addr_type;
uint8_t my_addr_len;
const uint8_t *my_addr_ptr;
const uint8_t *cp, *end;
uint8_t n_other_addrs;
time_t now = time(NULL);
long apparent_skew = 0;
uint32_t my_apparent_addr = 0;
if (conn->link_proto < 2) {
log_fn(LOG_PROTOCOL_WARN, LD_OR,
"Received a NETINFO cell on %s connection; dropping.",
conn->link_proto == 0 ? "non-versioned" : "a v1");
return;
}
if (conn->_base.state != OR_CONN_STATE_OR_HANDSHAKING_V2 &&
conn->_base.state != OR_CONN_STATE_OR_HANDSHAKING_V3) {
log_fn(LOG_PROTOCOL_WARN, LD_OR,
"Received a NETINFO cell on non-handshaking connection; dropping.");
return;
}
tor_assert(conn->handshake_state &&
conn->handshake_state->received_versions);
if (conn->_base.state == OR_CONN_STATE_OR_HANDSHAKING_V3) {
tor_assert(conn->link_proto >= 3);
if (conn->handshake_state->started_here) {
if (!conn->handshake_state->authenticated) {
log_fn(LOG_PROTOCOL_WARN, LD_OR, "Got a NETINFO cell from server, "
"but no authentication. Closing the connection.");
connection_mark_for_close(TO_CONN(conn));
return;
}
} else {
/* we're the server. If the client never authenticated, we have
some housekeeping to do.*/
if (!conn->handshake_state->authenticated) {
tor_assert(tor_digest_is_zero(
(const char*)conn->handshake_state->authenticated_peer_id));
connection_or_set_circid_type(conn, NULL);
connection_or_init_conn_from_address(conn,
&conn->_base.addr,
conn->_base.port,
(const char*)conn->handshake_state->authenticated_peer_id,
0);
}
}
}
/* Decode the cell. */
timestamp = ntohl(get_uint32(cell->payload));
if (labs(now - conn->handshake_state->sent_versions_at) < 180) {
apparent_skew = now - timestamp;
}
my_addr_type = (uint8_t) cell->payload[4];
my_addr_len = (uint8_t) cell->payload[5];
my_addr_ptr = (uint8_t*) cell->payload + 6;
end = cell->payload + CELL_PAYLOAD_SIZE;
cp = cell->payload + 6 + my_addr_len;
if (cp >= end) {
log_fn(LOG_PROTOCOL_WARN, LD_OR,
"Addresses too long in netinfo cell; closing connection.");
connection_mark_for_close(TO_CONN(conn));
return;
} else if (my_addr_type == RESOLVED_TYPE_IPV4 && my_addr_len == 4) {
my_apparent_addr = ntohl(get_uint32(my_addr_ptr));
}
n_other_addrs = (uint8_t) *cp++;
while (n_other_addrs && cp < end-2) {
/* Consider all the other addresses; if any matches, this connection is
* "canonical." */
tor_addr_t addr;
const uint8_t *next =
decode_address_from_payload(&addr, cp, (int)(end-cp));
if (next == NULL) {
log_fn(LOG_PROTOCOL_WARN, LD_OR,
"Bad address in netinfo cell; closing connection.");
connection_mark_for_close(TO_CONN(conn));
return;
}
if (tor_addr_eq(&addr, &conn->real_addr)) {
conn->is_canonical = 1;
break;
}
cp = next;
--n_other_addrs;
}
/* Act on apparent skew. */
/** Warn when we get a netinfo skew with at least this value. */
#define NETINFO_NOTICE_SKEW 3600
if (labs(apparent_skew) > NETINFO_NOTICE_SKEW &&
router_get_by_id_digest(conn->identity_digest)) {
char dbuf[64];
int severity;
/*XXXX be smarter about when everybody says we are skewed. */
if (router_digest_is_trusted_dir(conn->identity_digest))
severity = LOG_WARN;
else
severity = LOG_INFO;
format_time_interval(dbuf, sizeof(dbuf), apparent_skew);
log_fn(severity, LD_GENERAL, "Received NETINFO cell with skewed time from "
"server at %s:%d. It seems that our clock is %s by %s, or "
"that theirs is %s. Tor requires an accurate clock to work: "
"please check your time and date settings.",
conn->_base.address, (int)conn->_base.port,
apparent_skew>0 ? "ahead" : "behind", dbuf,
apparent_skew>0 ? "behind" : "ahead");
if (severity == LOG_WARN) /* only tell the controller if an authority */
control_event_general_status(LOG_WARN,
"CLOCK_SKEW SKEW=%ld SOURCE=OR:%s:%d",
apparent_skew,
conn->_base.address, conn->_base.port);
}
/* XXX maybe act on my_apparent_addr, if the source is sufficiently
* trustworthy. */
(void)my_apparent_addr;
if (connection_or_set_state_open(conn)<0) {
log_fn(LOG_PROTOCOL_WARN, LD_OR, "Got good NETINFO cell from %s:%d; but "
"was unable to make the OR connection become open.",
safe_str_client(conn->_base.address),
conn->_base.port);
connection_mark_for_close(TO_CONN(conn));
} else {
log_info(LD_OR, "Got good NETINFO cell from %s:%d; OR connection is now "
"open, using protocol version %d. Its ID digest is %s",
safe_str_client(conn->_base.address),
conn->_base.port, (int)conn->link_proto,
hex_str(conn->identity_digest, DIGEST_LEN));
}
assert_connection_ok(TO_CONN(conn),time(NULL));
}
/** Process a CERT cell from an OR connection.
*
* If the other side should not have sent us a CERT cell, or the cell is
* malformed, or it is supposed to authenticate the TLS key but it doesn't,
* then mark the connection.
*
* If the cell has a good cert chain and we're doing a v3 handshake, then
* store the certificates in or_handshake_state. If this is the client side
* of the connection, we then authenticate the server or mark the connection.
* If it's the server side, wait for an AUTHENTICATE cell.
*/
static void
command_process_cert_cell(var_cell_t *cell, or_connection_t *conn)
{
#define ERR(s) \
do { \
log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL, \
"Received a bad CERT cell from %s:%d: %s", \
safe_str(conn->_base.address), conn->_base.port, (s)); \
connection_mark_for_close(TO_CONN(conn)); \
goto err; \
} while (0)
tor_cert_t *link_cert = NULL;
tor_cert_t *id_cert = NULL;
tor_cert_t *auth_cert = NULL;
uint8_t *ptr;
int n_certs, i;
if (conn->_base.state != OR_CONN_STATE_OR_HANDSHAKING_V3)
ERR("We're not doing a v3 handshake!");
if (conn->link_proto < 3)
ERR("We're not using link protocol >= 3");
if (conn->handshake_state->received_cert_cell)
ERR("We already got one");
if (conn->handshake_state->authenticated) {
/* Should be unreachable, but let's make sure. */
ERR("We're already authenticated!");
}
if (cell->payload_len < 1)
ERR("It had no body");
if (cell->circ_id)
ERR("It had a nonzero circuit ID");
n_certs = cell->payload[0];
ptr = cell->payload + 1;
for (i = 0; i < n_certs; ++i) {
uint8_t cert_type;
uint16_t cert_len;
if (ptr + 3 > cell->payload + cell->payload_len) {
goto truncated;
}
cert_type = *ptr;
cert_len = ntohs(get_uint16(ptr+1));
if (ptr + 3 + cert_len > cell->payload + cell->payload_len) {
goto truncated;
}
if (cert_type == OR_CERT_TYPE_TLS_LINK ||
cert_type == OR_CERT_TYPE_ID_1024 ||
cert_type == OR_CERT_TYPE_AUTH_1024) {
tor_cert_t *cert = tor_cert_decode(ptr + 3, cert_len);
if (!cert) {
log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
"Received undecodable certificate in CERT cell from %s:%d",
safe_str(conn->_base.address), conn->_base.port);
} else {
if (cert_type == OR_CERT_TYPE_TLS_LINK) {
if (link_cert) {
tor_cert_free(cert);
ERR("Too many TLS_LINK certificates");
}
link_cert = cert;
} else if (cert_type == OR_CERT_TYPE_ID_1024) {
if (id_cert) {
tor_cert_free(cert);
ERR("Too many ID_1024 certificates");
}
id_cert = cert;
} else if (cert_type == OR_CERT_TYPE_AUTH_1024) {
if (auth_cert) {
tor_cert_free(cert);
ERR("Too many AUTH_1024 certificates");
}
auth_cert = cert;
} else {
tor_cert_free(cert);
}
}
}
ptr += 3 + cert_len;
continue;
truncated:
ERR("It ends in the middle of a certificate");
}
if (conn->handshake_state->started_here) {
if (! (id_cert && link_cert))
ERR("The certs we wanted were missing");
/* Okay. We should be able to check the certificates now. */
if (! tor_tls_cert_matches_key(conn->tls, link_cert)) {
ERR("The link certificate didn't match the TLS public key");
}
if (! tor_tls_cert_is_valid(link_cert, id_cert, 0))
ERR("The link certificate was not valid");
if (! tor_tls_cert_is_valid(id_cert, id_cert, 1))
ERR("The ID certificate was not valid");
conn->handshake_state->authenticated = 1;
{
const digests_t *id_digests = tor_cert_get_id_digests(id_cert);
crypto_pk_env_t *identity_rcvd;
if (!id_digests)
ERR("Couldn't compute digests for key in ID cert");
identity_rcvd = tor_tls_cert_get_key(id_cert);
if (!identity_rcvd)
ERR("Internal error: Couldn't get RSA key from ID cert.");
memcpy(conn->handshake_state->authenticated_peer_id,
id_digests->d[DIGEST_SHA1], DIGEST_LEN);
connection_or_set_circid_type(conn, identity_rcvd);
crypto_free_pk_env(identity_rcvd);
}
if (connection_or_client_learned_peer_id(conn,
conn->handshake_state->authenticated_peer_id) < 0)
ERR("Problem setting or checking peer id");
log_info(LD_OR, "Got some good certificates from %s:%d: Authenticated it.",
safe_str(conn->_base.address), conn->_base.port);
conn->handshake_state->id_cert = id_cert;
id_cert = NULL;
} else {
if (! (id_cert && auth_cert))
ERR("The certs we wanted were missing");
/* Remember these certificates so we can check an AUTHENTICATE cell */
if (! tor_tls_cert_is_valid(auth_cert, id_cert, 1))
ERR("The authentication certificate was not valid");
if (! tor_tls_cert_is_valid(id_cert, id_cert, 1))
ERR("The ID certificate was not valid");
log_info(LD_OR, "Got some good certificates from %s:%d: "
"Waiting for AUTHENTICATE.",
safe_str(conn->_base.address), conn->_base.port);
/* XXXX check more stuff? */
conn->handshake_state->id_cert = id_cert;
conn->handshake_state->auth_cert = auth_cert;
id_cert = auth_cert = NULL;
}
conn->handshake_state->received_cert_cell = 1;
err:
tor_cert_free(id_cert);
tor_cert_free(link_cert);
tor_cert_free(auth_cert);
#undef ERR
}
/** Process an AUTH_CHALLENGE cell from an OR connection.
*
* If we weren't supposed to get one (for example, because we're not the
* originator of the connection), or it's ill-formed, or we aren't doing a v3
* handshake, mark the connection. If the cell is well-formed but we don't
* want to authenticate, just drop it. If the cell is well-formed *and* we
* want to authenticate, send an AUTHENTICATE cell. */
static void
command_process_auth_challenge_cell(var_cell_t *cell, or_connection_t *conn)
{
int n_types, i, use_type = -1;
uint8_t *cp;
#define ERR(s) \
do { \
log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL, \
"Received a bad AUTH_CHALLENGE cell from %s:%d: %s", \
safe_str(conn->_base.address), conn->_base.port, (s)); \
connection_mark_for_close(TO_CONN(conn)); \
return; \
} while (0)
if (conn->_base.state != OR_CONN_STATE_OR_HANDSHAKING_V3)
ERR("We're not currently doing a v3 handshake");
if (conn->link_proto < 3)
ERR("We're not using link protocol >= 3");
if (! conn->handshake_state->started_here)
ERR("We didn't originate this connection");
if (conn->handshake_state->received_auth_challenge)
ERR("We already received one");
if (! conn->handshake_state->received_cert_cell)
ERR("We haven't gotten a CERTS cell yet");
if (cell->payload_len < OR_AUTH_CHALLENGE_LEN + 2)
ERR("It was too short");
if (cell->circ_id)
ERR("It had a nonzero circuit ID");
n_types = ntohs(get_uint16(cell->payload + OR_AUTH_CHALLENGE_LEN));
if (cell->payload_len < OR_AUTH_CHALLENGE_LEN + 2 + 2*n_types)
ERR("It looks truncated");
/* Now see if there is an authentication type we can use */
cp=cell->payload+OR_AUTH_CHALLENGE_LEN+2;
for (i=0; i < n_types; ++i, cp += 2) {
uint16_t authtype = ntohs(get_uint16(cp));
if (authtype == AUTHTYPE_RSA_SHA256_TLSSECRET)
use_type = authtype;
}
conn->handshake_state->received_auth_challenge = 1;
if (use_type >= 0 && public_server_mode(get_options())) {
log_info(LD_OR, "Got an AUTH_CHALLENGE cell from %s:%d: Sending "
"authentication",
safe_str(conn->_base.address), conn->_base.port);
if (connection_or_send_authenticate_cell(conn, use_type) < 0) {
log_warn(LD_OR, "Couldn't send authenticate cell");
connection_mark_for_close(TO_CONN(conn));
return;
}
if (connection_or_send_netinfo(conn) < 0) {
log_warn(LD_OR, "Couldn't send netinfo cell");
connection_mark_for_close(TO_CONN(conn));
return;
}
} else {
log_info(LD_OR, "Got an AUTH_CHALLENGE cell from %s:%d: Not "
"authenticating",
safe_str(conn->_base.address), conn->_base.port);
}
#undef ERR
}
/** Process an AUTHENTICATE cell from an OR connection.
*
* If it's ill-formed or we weren't supposed to get one or we're not doing a
* v3 handshake, then mark the connection. If it does not authenticate the
* other side of the connection successfully (because it isn't signed right,
* we didn't get a CERT cell, etc) mark the connection. Otherwise, accept
* the identity of the router on the other side of the connection.
*/
static void
command_process_authenticate_cell(var_cell_t *cell, or_connection_t *conn)
{
uint8_t expected[V3_AUTH_FIXED_PART_LEN];
const uint8_t *auth;
int authlen;
#define ERR(s) \
do { \
log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL, \
"Received a bad AUTHENTICATE cell from %s:%d: %s", \
safe_str(conn->_base.address), conn->_base.port, (s)); \
connection_mark_for_close(TO_CONN(conn)); \
return; \
} while (0)
if (conn->_base.state != OR_CONN_STATE_OR_HANDSHAKING_V3)
ERR("We're not doing a v3 handshake");
if (conn->link_proto < 3)
ERR("We're not using link protocol >= 3");
if (conn->handshake_state->started_here)
ERR("We originated this connection");
if (conn->handshake_state->received_authenticate)
ERR("We already got one!");
if (conn->handshake_state->authenticated) {
/* Should be impossible given other checks */
ERR("The peer is already authenticated");
}
if (! conn->handshake_state->received_cert_cell)
ERR("We never got a cert cell");
if (conn->handshake_state->auth_cert == NULL)
ERR("We never got an authentication certificate");
if (conn->handshake_state->id_cert == NULL)
ERR("We never got an identity certificate");
if (cell->payload_len < 4)
ERR("Cell was way too short");
auth = cell->payload;
{
uint16_t type = ntohs(get_uint16(auth));
uint16_t len = ntohs(get_uint16(auth+2));
if (4 + len > cell->payload_len)
ERR("Authenticator was truncated");
if (type != AUTHTYPE_RSA_SHA256_TLSSECRET)
ERR("Authenticator type was not recognized");
auth += 4;
authlen = len;
}
if (authlen < V3_AUTH_BODY_LEN + 1)
ERR("Authenticator was too short");
if (connection_or_compute_authenticate_cell_body(
conn, expected, sizeof(expected), NULL, 1) < 0)
ERR("Couldn't compute expected AUTHENTICATE cell body");
if (tor_memneq(expected, auth, sizeof(expected)))
ERR("Some field in the AUTHENTICATE cell body was not as expected");
{
crypto_pk_env_t *pk = tor_tls_cert_get_key(
conn->handshake_state->auth_cert);
char d[DIGEST256_LEN];
char *signed_data;
size_t keysize;
int signed_len;
if (!pk)
ERR("Internal error: couldn't get RSA key from AUTH cert.");
crypto_digest256(d, (char*)auth, V3_AUTH_BODY_LEN, DIGEST_SHA256);
keysize = crypto_pk_keysize(pk);
signed_data = tor_malloc(keysize);
signed_len = crypto_pk_public_checksig(pk, signed_data, keysize,
(char*)auth + V3_AUTH_BODY_LEN,
authlen - V3_AUTH_BODY_LEN);
crypto_free_pk_env(pk);
if (signed_len < 0) {
tor_free(signed_data);
ERR("Signature wasn't valid");
}
if (signed_len < DIGEST256_LEN) {
tor_free(signed_data);
ERR("Not enough data was signed");
}
/* Note that we deliberately allow *more* than DIGEST256_LEN bytes here,
* in case they're later used to hold a SHA3 digest or something. */
if (tor_memneq(signed_data, d, DIGEST256_LEN)) {
tor_free(signed_data);
ERR("Signature did not match data to be signed.");
}
tor_free(signed_data);
}
/* Okay, we are authenticated. */
conn->handshake_state->received_authenticate = 1;
conn->handshake_state->authenticated = 1;
conn->handshake_state->digest_received_data = 0;
{
crypto_pk_env_t *identity_rcvd =
tor_tls_cert_get_key(conn->handshake_state->id_cert);
const digests_t *id_digests =
tor_cert_get_id_digests(conn->handshake_state->id_cert);
/* This must exist; we checked key type when reading the cert. */
tor_assert(id_digests);
memcpy(conn->handshake_state->authenticated_peer_id,
id_digests->d[DIGEST_SHA1], DIGEST_LEN);
connection_or_set_circid_type(conn, identity_rcvd);
crypto_free_pk_env(identity_rcvd);
connection_or_init_conn_from_address(conn,
&conn->_base.addr,
conn->_base.port,
(const char*)conn->handshake_state->authenticated_peer_id,
0);
log_info(LD_OR, "Got an AUTHENTICATE cell from %s:%d: Looks good.",
safe_str(conn->_base.address), conn->_base.port);
}
#undef ERR
}
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