nihilist/tor
1
0
Fork 0
mirror of https://gitlab.torproject.org/tpo/core/tor.git synced 2024-11-27 22:03:31 +01:00
Code Issues Packages Projects Releases Wiki Activity

hs: Remove introduction point v2 support

Browse Source 
Related to #40266

Signed-off-by: David Goulet <dgoulet@torproject.org>
This commit is contained in:
David Goulet 2021-02-16 09:27:45 -05:00
parent 2c865542b6
commit ca04e9b8ed
3 changed files with 5 additions and 241 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

40
src/feature/hs/hs_intropoint.c
View File

@ -494,8 +494,8 @@ hs_intro_circuit_is_suitable_for_establish_intro(const or_circuit_t *circ)
return circuit_is_suitable_intro_point(circ, "ESTABLISH_INTRO");
}
/** We just received an ESTABLISH_INTRO cell in <b>circ</b>. Figure out of it's
* a legacy or a next gen cell, and pass it to the appropriate handler. */
/** We just received an ESTABLISH_INTRO cell in <b>circ</b>. Pass it to the
* appropriate handler. */
int
hs_intro_received_establish_intro(or_circuit_t *circ, const uint8_t *request,
size_t request_len)
@ -512,9 +512,6 @@ hs_intro_received_establish_intro(or_circuit_t *circ, const uint8_t *request,
* ESTABLISH_INTRO and pass it to the appropriate cell handler */
const uint8_t first_byte = request[0];
switch (first_byte) {
case TRUNNEL_HS_INTRO_AUTH_KEY_TYPE_LEGACY0:
case TRUNNEL_HS_INTRO_AUTH_KEY_TYPE_LEGACY1:
return rend_mid_establish_intro_legacy(circ, request, request_len);
case TRUNNEL_HS_INTRO_AUTH_KEY_TYPE_ED25519:
return handle_establish_intro(circ, request, request_len);
default:
@ -717,23 +714,6 @@ handle_introduce1(or_circuit_t *client_circ, const uint8_t *request,
return ret;
}
/** Identify if the encoded cell we just received is a legacy one or not. The
* <b>request</b> should be at least DIGEST_LEN bytes long. */
STATIC int
introduce1_cell_is_legacy(const uint8_t *request)
{
tor_assert(request);
/* If the first 20 bytes of the cell (DIGEST_LEN) are NOT zeroes, it
* indicates a legacy cell (v2). */
if (!fast_mem_is_zero((const char *) request, DIGEST_LEN)) {
/* Legacy cell. */
return 1;
}
/* Not a legacy cell. */
return 0;
}
/** Return true iff the circuit <b>circ</b> is suitable for receiving an
* INTRODUCE1 cell. */
STATIC int
@ -772,13 +752,10 @@ int
hs_intro_received_introduce1(or_circuit_t *circ, const uint8_t *request,
size_t request_len)
{
int ret;
tor_assert(circ);
tor_assert(request);
/* A cell that can't hold a DIGEST_LEN is invalid as we need to check if
* it's a legacy cell or not using the first DIGEST_LEN bytes. */
/* A cell that can't hold a DIGEST_LEN is invalid. */
if (request_len < DIGEST_LEN) {
log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL, "Invalid INTRODUCE1 cell length.");
goto err;
@ -794,15 +771,8 @@ hs_intro_received_introduce1(or_circuit_t *circ, const uint8_t *request,
* DoS mitigation since one circuit with one client can hammer a service. */
circ->already_received_introduce1 = 1;
/* We are sure here to have at least DIGEST_LEN bytes. */
if (introduce1_cell_is_legacy(request)) {
/* Handle a legacy cell. */
ret = rend_mid_introduce_legacy(circ, request, request_len);
} else {
/* Handle a non legacy cell. */
ret = handle_introduce1(circ, request, request_len);
}
return ret;
/* Handle the cell. */
return handle_introduce1(circ, request, request_len);
err:
circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_TORPROTOCOL);

1
src/feature/hs/hs_intropoint.h
View File

@ -52,7 +52,6 @@ STATIC void
get_auth_key_from_cell(ed25519_public_key_t *auth_key_out,
unsigned int cell_type, const void *cell);
STATIC int introduce1_cell_is_legacy(const uint8_t *request);
STATIC int handle_introduce1(or_circuit_t *client_circ,
const uint8_t *request, size_t request_len);
STATIC int validate_introduce1_parsed_cell(const trn_cell_introduce1_t *cell);

205
src/feature/rend/rendmid.c
View File

@ -16,217 +16,12 @@
#include "core/or/dos.h"
#include "core/or/relay.h"
#include "feature/rend/rendmid.h"
#include "feature/stats/rephist.h"
#include "feature/hs/hs_circuitmap.h"
#include "feature/hs/hs_dos.h"
#include "feature/hs/hs_intropoint.h"
#include "core/or/or_circuit_st.h"
/** Respond to an ESTABLISH_INTRO cell by checking the signed data and
* setting the circuit's purpose and service pk digest.
*/
int
rend_mid_establish_intro_legacy(or_circuit_t *circ, const uint8_t *request,
size_t request_len)
{
crypto_pk_t *pk = NULL;
char buf[DIGEST_LEN+9];
char expected_digest[DIGEST_LEN];
char pk_digest[DIGEST_LEN];
size_t asn1len;
or_circuit_t *c;
char serviceid[REND_SERVICE_ID_LEN_BASE32+1];
int reason = END_CIRC_REASON_INTERNAL;
log_info(LD_REND,
"Received a legacy ESTABLISH_INTRO request on circuit %u",
(unsigned) circ->p_circ_id);
if (!hs_intro_circuit_is_suitable_for_establish_intro(circ)) {
reason = END_CIRC_REASON_TORPROTOCOL;
goto err;
}
if (request_len < 2+DIGEST_LEN)
goto truncated;
/* First 2 bytes: length of asn1-encoded key. */
asn1len = ntohs(get_uint16(request));
/* Next asn1len bytes: asn1-encoded key. */
if (request_len < 2+DIGEST_LEN+asn1len)
goto truncated;
pk = crypto_pk_asn1_decode((char*)(request+2), asn1len);
if (!pk) {
reason = END_CIRC_REASON_TORPROTOCOL;
log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL, "Couldn't decode public key.");
goto err;
}
/* Next 20 bytes: Hash of rend_circ_nonce | "INTRODUCE" */
memcpy(buf, circ->rend_circ_nonce, DIGEST_LEN);
memcpy(buf+DIGEST_LEN, "INTRODUCE", 9);
if (crypto_digest(expected_digest, buf, DIGEST_LEN+9) < 0) {
log_warn(LD_BUG, "Internal error computing digest.");
goto err;
}
if (tor_memneq(expected_digest, request+2+asn1len, DIGEST_LEN)) {
log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
"Hash of session info was not as expected.");
reason = END_CIRC_REASON_TORPROTOCOL;
goto err;
}
/* Rest of body: signature of previous data */
if (crypto_pk_public_checksig_digest(pk,
(char*)request, 2+asn1len+DIGEST_LEN,
(char*)(request+2+DIGEST_LEN+asn1len),
request_len-(2+DIGEST_LEN+asn1len))<0) {
log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
"Incorrect signature on ESTABLISH_INTRO cell; rejecting.");
reason = END_CIRC_REASON_TORPROTOCOL;
goto err;
}
/* The request is valid. First, compute the hash of the service's PK.*/
if (crypto_pk_get_digest(pk, pk_digest)<0) {
log_warn(LD_BUG, "Internal error: couldn't hash public key.");
goto err;
}
crypto_pk_free(pk); /* don't need it anymore */
pk = NULL; /* so we don't free it again if err */
base32_encode(serviceid, REND_SERVICE_ID_LEN_BASE32+1,
pk_digest, REND_SERVICE_ID_LEN);
/* Close any other intro circuits with the same pk. */
c = NULL;
while ((c = hs_circuitmap_get_intro_circ_v2_relay_side(
(const uint8_t *)pk_digest))) {
log_info(LD_REND, "Replacing old circuit for service %s",
safe_str(serviceid));
circuit_mark_for_close(TO_CIRCUIT(c), END_CIRC_REASON_FINISHED);
/* Now it's marked, and it won't be returned next time. */
}
/* Acknowledge the request. */
if (hs_intro_send_intro_established_cell(circ) < 0) {
log_info(LD_GENERAL, "Couldn't send INTRO_ESTABLISHED cell.");
goto err_no_close;
}
/* Now, set up this circuit. */
circuit_change_purpose(TO_CIRCUIT(circ), CIRCUIT_PURPOSE_INTRO_POINT);
hs_circuitmap_register_intro_circ_v2_relay_side(circ, (uint8_t *)pk_digest);
hs_dos_setup_default_intro2_defenses(circ);
log_info(LD_REND,
"Established introduction point on circuit %u for service %s",
(unsigned) circ->p_circ_id, safe_str(serviceid));
return 0;
truncated:
log_warn(LD_PROTOCOL, "Rejecting truncated ESTABLISH_INTRO cell.");
reason = END_CIRC_REASON_TORPROTOCOL;
err:
circuit_mark_for_close(TO_CIRCUIT(circ), reason);
err_no_close:
if (pk) crypto_pk_free(pk);
return -1;
}
/** Process an INTRODUCE1 cell by finding the corresponding introduction
* circuit, and relaying the body of the INTRODUCE1 cell inside an
* INTRODUCE2 cell.
*/
int
rend_mid_introduce_legacy(or_circuit_t *circ, const uint8_t *request,
size_t request_len)
{
or_circuit_t *intro_circ;
char serviceid[REND_SERVICE_ID_LEN_BASE32+1];
char nak_body[1];
log_info(LD_REND, "Received an INTRODUCE1 request on circuit %u",
(unsigned)circ->p_circ_id);
/* At this point, we know that the circuit is valid for an INTRODUCE1
* because the validation has been made before calling this function. */
tor_assert(circ->base_.purpose == CIRCUIT_PURPOSE_OR);
tor_assert(!circ->base_.n_chan);
/* We could change this to MAX_HEX_NICKNAME_LEN now that 0.0.9.x is
* obsolete; however, there isn't much reason to do so, and we're going
* to revise this protocol anyway.
*/
if (request_len < (DIGEST_LEN+(MAX_NICKNAME_LEN+1)+REND_COOKIE_LEN+
DH1024_KEY_LEN+CIPHER_KEY_LEN+
PKCS1_OAEP_PADDING_OVERHEAD)) {
log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
"Impossibly short INTRODUCE1 cell on circuit %u; "
"responding with nack.", (unsigned)circ->p_circ_id);
goto err;
}
base32_encode(serviceid, REND_SERVICE_ID_LEN_BASE32+1,
(char*)request, REND_SERVICE_ID_LEN);
/* The first 20 bytes are all we look at: they have a hash of the service's
* PK. */
intro_circ = hs_circuitmap_get_intro_circ_v2_relay_side(
(const uint8_t*)request);
if (!intro_circ) {
log_info(LD_REND,
"No intro circ found for INTRODUCE1 cell (%s) from circuit %u; "
"responding with nack.",
safe_str(serviceid), (unsigned)circ->p_circ_id);
goto err;
}
/* Before sending, lets make sure this cell can be sent on the service
* circuit asking the DoS defenses. */
if (!hs_dos_can_send_intro2(intro_circ)) {
log_info(LD_PROTOCOL, "Can't relay INTRODUCE1 v2 cell due to DoS "
"limitations. Sending NACK to client.");
goto err;
}
log_info(LD_REND,
"Sending introduction request for service %s "
"from circ %u to circ %u",
safe_str(serviceid), (unsigned)circ->p_circ_id,
(unsigned)intro_circ->p_circ_id);
/* Great. Now we just relay the cell down the circuit. */
if (relay_send_command_from_edge(0, TO_CIRCUIT(intro_circ),
RELAY_COMMAND_INTRODUCE2,
(char*)request, request_len, NULL)) {
log_warn(LD_GENERAL,
"Unable to send INTRODUCE2 cell to Tor client.");
/* Stop right now, the circuit has been closed. */
return -1;
}
/* And send an ack down the client's circuit. Empty body means succeeded. */
if (relay_send_command_from_edge(0,TO_CIRCUIT(circ),
RELAY_COMMAND_INTRODUCE_ACK,
NULL,0,NULL)) {
log_warn(LD_GENERAL, "Unable to send INTRODUCE_ACK cell to Tor client.");
/* Stop right now, the circuit has been closed. */
return -1;
}
return 0;
err:
/* Send the client a NACK */
nak_body[0] = 1;
if (relay_send_command_from_edge(0,TO_CIRCUIT(circ),
RELAY_COMMAND_INTRODUCE_ACK,
nak_body, 1, NULL)) {
log_warn(LD_GENERAL, "Unable to send NAK to Tor client.");
}
return -1;
}
/** Process an ESTABLISH_RENDEZVOUS cell by setting the circuit's purpose and
* rendezvous cookie.
*/