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Implement congestion control parameter negotiation

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This commit is contained in:
Mike Perry 2021-11-04 00:44:38 +00:00
parent 095224cdfa
commit b6d5fbba7d
3 changed files with 198 additions and 34 deletions
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200
src/core/crypto/onion_crypto.c
View File

@ -41,15 +41,17 @@
#include "lib/crypt_ops/crypto_dh.h"
#include "lib/crypt_ops/crypto_util.h"
#include "feature/relay/routerkeys.h"
#include "core/or/congestion_control_common.h"
#include "core/or/circuitbuild.h"
#include "core/or/crypt_path_st.h"
#include "core/or/extend_info_st.h"
#include "trunnel/circ_params.h"
/* TODO-324: Add this to the specification! */
const uint8_t NTOR3_CIRC_VERIFICATION[] = "circuit extend";
const size_t NTOR3_CIRC_VERIFICATION_LEN = 14;
static const uint8_t NTOR3_CIRC_VERIFICATION[] = "circuit extend";
static const size_t NTOR3_CIRC_VERIFICATION_LEN = 14;
#define NTOR3_VERIFICATION_ARGS \
NTOR3_CIRC_VERIFICATION, NTOR3_CIRC_VERIFICATION_LEN
@ -210,6 +212,93 @@ onion_skin_create(int type,
return r;
}
/**
* Takes a param request message from the client, compares it to our
* consensus parameters, and creates a reply message and output
* parameters.
*
* This function runs in a worker thread, so it can only inspect
* arguments and local variables.
*
* Returns 0 if successful.
* Returns -1 on parsing, parameter failure, or reply creation failure.
*/
static int
negotiate_v3_ntor_server_circ_params(const uint8_t *param_request_msg,
size_t param_request_len,
const circuit_params_t *our_ns_params,
circuit_params_t *params_out,
uint8_t **resp_msg_out,
size_t *resp_msg_len_out)
{
circ_params_response_t *resp = NULL;
circ_params_request_t *param_request = NULL;
ssize_t resp_msg_len;
if (circ_params_request_parse(&param_request, param_request_msg,
param_request_len) < 0) {
return -1;
}
/* CC is enabled if the client wants it, and our consensus paramers
* allow it. If both are true, its on. If either is false, it's off. */
params_out->cc_enabled =
circ_params_request_get_cc_supported(param_request) &&
our_ns_params->cc_enabled;
resp = circ_params_response_new();
if (circ_params_response_set_version(resp, 0) < 0) {
circ_params_request_free(param_request);
circ_params_response_free(resp);
return -1;
}
/* The relay always chooses its sendme_inc, and sends it to the client */
params_out->sendme_inc_cells = our_ns_params->sendme_inc_cells;
if (circ_params_response_set_sendme_inc_cells(resp,
our_ns_params->sendme_inc_cells) < 0) {
circ_params_request_free(param_request);
circ_params_response_free(resp);
return -1;
}
/* Use the negotiated cc_enabled value to respond */
if (circ_params_response_set_cc_enabled(resp, params_out->cc_enabled) < 0) {
circ_params_request_free(param_request);
circ_params_response_free(resp);
return -1;
}
resp_msg_len = circ_params_response_encoded_len(resp);
if (resp_msg_len < 0) {
circ_params_request_free(param_request);
circ_params_response_free(resp);
return -1;
}
*resp_msg_out = tor_malloc_zero(resp_msg_len);
resp_msg_len = circ_params_response_encode(*resp_msg_out, resp_msg_len,
resp);
if (resp_msg_len < 0) {
circ_params_request_free(param_request);
circ_params_response_free(resp);
tor_free(*resp_msg_out);
return -1;
}
*resp_msg_len_out = (size_t)resp_msg_len;
circ_params_request_free(param_request);
circ_params_response_free(resp);
return 0;
}
/* This is the maximum value for keys_out_len passed to
* onion_skin_server_handshake, plus 16. We can make it bigger if needed:
* It just defines how many bytes to stack-allocate. */
@ -226,6 +315,7 @@ int
onion_skin_server_handshake(int type,
const uint8_t *onion_skin, size_t onionskin_len,
const server_onion_keys_t *keys,
const circuit_params_t *our_ns_params,
uint8_t *reply_out,
size_t reply_out_maxlen,
uint8_t *keys_out, size_t keys_out_len,
@ -233,7 +323,7 @@ onion_skin_server_handshake(int type,
circuit_params_t *params_out)
{
int r = -1;
memset(params_out, 0, sizeof(*params_out)); // TODO-324: actually set this!
memset(params_out, 0, sizeof(*params_out));
switch (type) {
case ONION_HANDSHAKE_TYPE_TAP:
@ -290,6 +380,9 @@ onion_skin_server_handshake(int type,
uint8_t keys_tmp[MAX_KEYS_TMP_LEN];
uint8_t *client_msg = NULL;
size_t client_msg_len = 0;
uint8_t *reply_msg = NULL;
size_t reply_msg_len = 0;
ntor3_server_handshake_state_t *state = NULL;
if (onion_skin_ntor3_server_handshake_part1(
@ -303,25 +396,17 @@ onion_skin_server_handshake(int type,
return -1;
}
uint8_t reply_msg[1] = { 0 };
size_t reply_msg_len = 1;
{
/* TODO-324, Okay, we have a message from the client trying to negotiate
* parameters. We need to decide whether the client's request is okay,
* what we're going to say in response, and what circuit parameters
* we've just negotiated
*/
/* NOTE! DANGER, DANGER, DANGER!
Remember that this function can be run in a worker thread, and so
therefore you can't access "global" state that isn't lock-protected.
CAVEAT HAXX0R!
*/
if (negotiate_v3_ntor_server_circ_params(client_msg,
client_msg_len,
our_ns_params,
params_out,
&reply_msg,
&reply_msg_len) < 0) {
ntor3_server_handshake_state_free(state);
tor_free(client_msg);
return -1;
}
tor_free(client_msg);
uint8_t *server_handshake = NULL;
size_t server_handshake_len = 0;
@ -331,12 +416,15 @@ onion_skin_server_handshake(int type,
reply_msg, reply_msg_len,
&server_handshake, &server_handshake_len,
keys_tmp, keys_tmp_len) < 0) {
// XXX TODO-324 free some stuff
tor_free(reply_msg);
ntor3_server_handshake_state_free(state);
return -1;
}
tor_free(reply_msg);
if (server_handshake_len > reply_out_maxlen) {
// XXX TODO-324 free that stuff
tor_free(server_handshake);
ntor3_server_handshake_state_free(state);
return -1;
}
@ -346,6 +434,7 @@ onion_skin_server_handshake(int type,
memwipe(keys_tmp, 0, keys_tmp_len);
memwipe(server_handshake, 0, server_handshake_len);
tor_free(server_handshake);
ntor3_server_handshake_state_free(state);
r = (int) server_handshake_len;
}
@ -362,6 +451,61 @@ onion_skin_server_handshake(int type,
return r;
}
/**
* Takes a param response message from the exit, compares it to our
* consensus parameters for sanity, and creates output parameters
* if sane.
*
* Returns -1 on parsing or insane params, 0 if success.
*/
static int
negotiate_v3_ntor_client_circ_params(const uint8_t *param_response_msg,
size_t param_response_len,
circuit_params_t *params_out)
{
circ_params_response_t *param_response = NULL;
bool cc_enabled;
uint8_t sendme_inc_cells;
if (circ_params_response_parse(&param_response, param_response_msg,
param_response_len) < 0) {
return -1;
}
cc_enabled =
circ_params_response_get_cc_enabled(param_response);
/* If congestion control came back enabled, but we didn't ask for it
* because the consensus said no, close the circuit */
if (cc_enabled && !congestion_control_enabled()) {
circ_params_response_free(param_response);
return -1;
}
params_out->cc_enabled = cc_enabled;
/* We will only accept this response (and this circuit) if sendme_inc
* is within a factor of 2 of our consensus value. We should not need
* to change cc_sendme_inc much, and if we do, we can spread out those
* changes over smaller increments once every 4 hours. Exits that
* violate this range should just not be used. */
#define MAX_SENDME_INC_NEGOTIATE_FACTOR 2
sendme_inc_cells =
circ_params_response_get_sendme_inc_cells(param_response);
if (sendme_inc_cells >
MAX_SENDME_INC_NEGOTIATE_FACTOR*congestion_control_sendme_inc() ||
sendme_inc_cells <
congestion_control_sendme_inc()/MAX_SENDME_INC_NEGOTIATE_FACTOR) {
circ_params_response_free(param_response);
return -1;
}
params_out->sendme_inc_cells = sendme_inc_cells;
circ_params_response_free(param_response);
return 0;
}
/** Perform the final (client-side) step of a circuit-creation handshake of
* type <b>type</b>, using our state in <b>handshake_state</b> and the
* server's response in <b>reply</b>. On success, generate <b>keys_out_len</b>
@ -382,7 +526,7 @@ onion_skin_client_handshake(int type,
if (handshake_state->tag != type)
return -1;
memset(params_out, 0, sizeof(*params_out)); // TODO-324: actually set this!
memset(params_out, 0, sizeof(*params_out));
switch (type) {
case ONION_HANDSHAKE_TYPE_TAP:
@ -450,10 +594,12 @@ onion_skin_client_handshake(int type,
return -1;
}
{
// XXXX TODO-324: see what the server said, make sure it's okay, see what
// parameters it gave us, make sure we like them, and put them into
// `params_out`
if (negotiate_v3_ntor_client_circ_params(server_msg,
server_msg_len,
params_out) < 0) {
tor_free(keys_tmp);
tor_free(server_msg);
return -1;
}
tor_free(server_msg);

10
src/core/crypto/onion_crypto.h
View File

@ -29,10 +29,11 @@ void onion_handshake_state_release(onion_handshake_state_t *state);
* Parameters negotiated as part of a circuit handshake.
*/
typedef struct circuit_params_t {
/* placeholder field for congestion control algorithm. Right now this
* is always set to zero */
int cc_algorithm;
int cc_window;
/** Is true if congestion control is enabled in consensus or param,
* as per congestion_control_enabled() result. */
bool cc_enabled;
/** The number of cells in a sendme increment. Only used if cc_enabled=1. */
uint8_t sendme_inc_cells;
} circuit_params_t;
int onion_skin_create(int type,
@ -43,6 +44,7 @@ int onion_skin_create(int type,
int onion_skin_server_handshake(int type,
const uint8_t *onion_skin, size_t onionskin_len,
const server_onion_keys_t *keys,
const circuit_params_t *ns_params,
uint8_t *reply_out,
size_t reply_out_maxlen,
uint8_t *keys_out, size_t key_out_len,

22
src/core/mainloop/cpuworker.c
View File

@ -21,6 +21,8 @@
#include "core/or/channel.h"
#include "core/or/circuitlist.h"
#include "core/or/connection_or.h"
#include "core/or/congestion_control_common.h"
#include "core/or/congestion_control_flow.h"
#include "app/config/config.h"
#include "core/mainloop/cpuworker.h"
#include "lib/crypt_ops/crypto_rand.h"
@ -126,6 +128,11 @@ typedef struct cpuworker_request_t {
/** A create cell for the cpuworker to process. */
create_cell_t create_cell;
/**
* A copy of this relay's consensus params that are relevant to
* the circuit, for use in negotiation. */
circuit_params_t circ_ns_params;
/* Turn the above into a tagged union if needed. */
} cpuworker_request_t;
@ -381,6 +388,12 @@ cpuworker_onion_handshake_replyfn(void *work_)
goto done_processing;
}
/* If the client asked for congestion control, if our consensus parameter
* allowed it to negotiate as enabled, allocate a congestion control obj. */
if (rpl.circ_params.cc_enabled) {
TO_CIRCUIT(circ)->ccontrol = congestion_control_new(&rpl.circ_params);
}
if (onionskin_answer(circ,
&rpl.created_cell,
(const char*)rpl.keys, sizeof(rpl.keys),
@ -390,9 +403,6 @@ cpuworker_onion_handshake_replyfn(void *work_)
goto done_processing;
}
/* TODO-324! We need to use rpl.circ_params here to initialize the congestion
control parameters of the circuit. */
log_debug(LD_OR,"onionskin_answer succeeded. Yay.");
done_processing:
@ -431,6 +441,7 @@ cpuworker_onion_handshake_threadfn(void *state_, void *work_)
n = onion_skin_server_handshake(cc->handshake_type,
cc->onionskin, cc->handshake_len,
onion_keys,
&req.circ_ns_params,
cell_out->reply,
sizeof(cell_out->reply),
rpl.keys, CPATH_KEY_MATERIAL_LEN,
@ -559,6 +570,11 @@ assign_onionskin_to_cpuworker(or_circuit_t *circ,
if (should_time)
tor_gettimeofday(&req.started_at);
/* Copy the current cached consensus params relevant to
* circuit negotiation into the CPU worker context */
req.circ_ns_params.cc_enabled = congestion_control_enabled();
req.circ_ns_params.sendme_inc_cells = congestion_control_sendme_inc();
job = tor_malloc_zero(sizeof(cpuworker_job_t));
job->circ = circ;
memcpy(&job->u.request, &req, sizeof(req));