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Send and receive AUTHENTICATE cells correctly with ED keys.

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Includes updated test for authchallenge cells
This commit is contained in:
Nick Mathewson 2016-08-30 10:33:57 -04:00
parent e64bac6eb4
commit 88c2a6b936
4 changed files with 112 additions and 33 deletions
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67
src/or/channeltls.c
View File

@ -2071,9 +2071,13 @@ channel_tls_process_auth_challenge_cell(var_cell_t *cell, channel_tls_t *chan)
/* Now see if there is an authentication type we can use */
for (i = 0; i < n_types; ++i) {
uint16_t authtype = auth_challenge_cell_get_methods(ac, i);
if (authtype == AUTHTYPE_RSA_SHA256_TLSSECRET)
if (authchallenge_type_is_supported(authtype)) {
if (use_type == -1 ||
authchallenge_type_is_better(authtype, use_type)) {
use_type = authtype;
}
}
}
chan->conn->handshake_state->received_auth_challenge = 1;
@ -2087,9 +2091,10 @@ channel_tls_process_auth_challenge_cell(var_cell_t *cell, channel_tls_t *chan)
if (use_type >= 0) {
log_info(LD_OR,
"Got an AUTH_CHALLENGE cell from %s:%d: Sending "
"authentication",
"authentication type %d",
safe_str(chan->conn->base_.address),
chan->conn->base_.port);
chan->conn->base_.port,
use_type);
if (connection_or_send_authenticate_cell(chan->conn, use_type) < 0) {
log_warn(LD_OR,
@ -2133,7 +2138,7 @@ channel_tls_process_authenticate_cell(var_cell_t *cell, channel_tls_t *chan)
var_cell_t *expected_cell = NULL;
const uint8_t *auth;
int authlen;
const int authtype = 1; /* XXXX extend this */
int authtype;
int bodylen;
tor_assert(cell);
@ -2165,8 +2170,6 @@ channel_tls_process_authenticate_cell(var_cell_t *cell, channel_tls_t *chan)
}
if (!(chan->conn->handshake_state->received_certs_cell))
ERR("We never got a certs cell");
if (chan->conn->handshake_state->certs->auth_cert == NULL)
ERR("We never got an authentication certificate");
if (chan->conn->handshake_state->certs->id_cert == NULL)
ERR("We never got an identity certificate");
if (cell->payload_len < 4)
@ -2179,8 +2182,9 @@ channel_tls_process_authenticate_cell(var_cell_t *cell, channel_tls_t *chan)
if (4 + len > cell->payload_len)
ERR("Authenticator was truncated");
if (type != authtype)
if (! authchallenge_type_is_supported(type))
ERR("Authenticator type was not recognized");
authtype = type;
auth += 4;
authlen = len;
@ -2194,11 +2198,18 @@ channel_tls_process_authenticate_cell(var_cell_t *cell, channel_tls_t *chan)
if (! expected_cell)
ERR("Couldn't compute expected AUTHENTICATE cell body");
int sig_is_rsa;
if (authtype == AUTHTYPE_RSA_SHA256_TLSSECRET ||
authtype == AUTHTYPE_RSA_SHA256_RFC5705) {
bodylen = V3_AUTH_BODY_LEN;
sig_is_rsa = 1;
} else {
bodylen = authlen - ED25519_SIG_LEN; /* XXXX DOCDOC */
tor_assert(authtype == AUTHTYPE_ED25519_SHA256_RFC5705);
/* Our earlier check had better have made sure we had room
* for an ed25519 sig (inadvertently) */
tor_assert(V3_AUTH_BODY_LEN > ED25519_SIG_LEN);
bodylen = authlen - ED25519_SIG_LEN;
sig_is_rsa = 0;
}
if (expected_cell->payload_len != bodylen+4) {
ERR("Expected AUTHENTICATE cell body len not as expected.");
@ -2211,7 +2222,13 @@ channel_tls_process_authenticate_cell(var_cell_t *cell, channel_tls_t *chan)
if (tor_memneq(expected_cell->payload+4, auth, bodylen-24))
ERR("Some field in the AUTHENTICATE cell body was not as expected");
{
if (sig_is_rsa) {
if (chan->conn->handshake_state->certs->ed_id_sign != NULL)
ERR("RSA-signed AUTHENTICATE response provided with an ED25519 cert");
if (chan->conn->handshake_state->certs->auth_cert == NULL)
ERR("We never got an RSA authentication certificate");
crypto_pk_t *pk = tor_tls_cert_get_key(
chan->conn->handshake_state->certs->auth_cert);
char d[DIGEST256_LEN];
@ -2231,7 +2248,7 @@ channel_tls_process_authenticate_cell(var_cell_t *cell, channel_tls_t *chan)
crypto_pk_free(pk);
if (signed_len < 0) {
tor_free(signed_data);
ERR("Signature wasn't valid");
ERR("RSA signature wasn't valid");
}
if (signed_len < DIGEST256_LEN) {
tor_free(signed_data);
@ -2244,6 +2261,20 @@ channel_tls_process_authenticate_cell(var_cell_t *cell, channel_tls_t *chan)
ERR("Signature did not match data to be signed.");
}
tor_free(signed_data);
} else {
if (chan->conn->handshake_state->certs->ed_id_sign == NULL)
ERR("We never got an Ed25519 identity certificate.");
if (chan->conn->handshake_state->certs->ed_sign_auth == NULL)
ERR("We never got an Ed25519 authentication certificate.");
const ed25519_public_key_t *authkey =
&chan->conn->handshake_state->certs->ed_sign_auth->signed_key;
ed25519_signature_t sig;
tor_assert(authlen > ED25519_SIG_LEN);
memcpy(&sig.sig, auth + authlen - ED25519_SIG_LEN, ED25519_SIG_LEN);
if (ed25519_checksig(&sig, auth, authlen - ED25519_SIG_LEN, authkey)<0) {
ERR("Ed25519 signature wasn't valid.");
}
}
/* Okay, we are authenticated. */
@ -2256,6 +2287,15 @@ channel_tls_process_authenticate_cell(var_cell_t *cell, channel_tls_t *chan)
tor_tls_cert_get_key(chan->conn->handshake_state->certs->id_cert);
const common_digests_t *id_digests =
tor_x509_cert_get_id_digests(chan->conn->handshake_state->certs->id_cert);
const ed25519_public_key_t *ed_identity_received = NULL;
if (! sig_is_rsa) {
chan->conn->handshake_state->authenticated_ed25519 = 1;
ed_identity_received =
&chan->conn->handshake_state->certs->ed_id_sign->signing_key;
memcpy(&chan->conn->handshake_state->authenticated_ed25519_peer_id,
ed_identity_received, sizeof(ed25519_public_key_t));
}
/* This must exist; we checked key type when reading the cert. */
tor_assert(id_digests);
@ -2272,13 +2312,14 @@ channel_tls_process_authenticate_cell(var_cell_t *cell, channel_tls_t *chan)
chan->conn->base_.port,
(const char*)(chan->conn->handshake_state->
authenticated_rsa_peer_id),
NULL, // XXXX Ed key
ed_identity_received,
0);
log_info(LD_OR,
"Got an AUTHENTICATE cell from %s:%d: Looks good.",
"Got an AUTHENTICATE cell from %s:%d, type %d: Looks good.",
safe_str(chan->conn->base_.address),
chan->conn->base_.port);
chan->conn->base_.port,
authtype);
}
var_cell_free(expected_cell);

43
src/or/connection_or.c
View File

@ -2271,6 +2271,38 @@ connection_or_send_certs_cell(or_connection_t *conn)
return 0;
}
/** Return true iff <b>challenge_type</b> is an AUTHCHALLENGE type that
* we can send and receive. */
int
authchallenge_type_is_supported(uint16_t challenge_type)
{
switch (challenge_type) {
case AUTHTYPE_RSA_SHA256_TLSSECRET:
case AUTHTYPE_RSA_SHA256_RFC5705:
case AUTHTYPE_ED25519_SHA256_RFC5705:
return 1;
default:
return 0;
}
}
/** Return true iff <b>challenge_type_a</b> is one that we would rather
* use than <b>challenge_type_b</b>. */
int
authchallenge_type_is_better(uint16_t challenge_type_a,
uint16_t challenge_type_b)
{
/* Any supported type is better than an unsupported one;
* all unsupported types are equally bad. */
if (!authchallenge_type_is_supported(challenge_type_a))
return 0;
if (!authchallenge_type_is_supported(challenge_type_b))
return 1;
/* It happens that types are superior in numerically ascending order.
* If that ever changes, this must change too. */
return (challenge_type_a > challenge_type_b);
}
/** Send an AUTH_CHALLENGE cell on the connection <b>conn</b>. Return 0
* on success, -1 on failure. */
int
@ -2285,9 +2317,12 @@ connection_or_send_auth_challenge_cell(or_connection_t *conn)
auth_challenge_cell_t *ac = auth_challenge_cell_new();
tor_assert(sizeof(ac->challenge) == 32);
crypto_rand((char*)ac->challenge, sizeof(ac->challenge));
auth_challenge_cell_add_methods(ac, AUTHTYPE_RSA_SHA256_TLSSECRET);
auth_challenge_cell_add_methods(ac, AUTHTYPE_RSA_SHA256_RFC5705);
auth_challenge_cell_add_methods(ac, AUTHTYPE_ED25519_SHA256_RFC5705);
auth_challenge_cell_set_n_methods(ac,
auth_challenge_cell_getlen_methods(ac));
@ -2330,7 +2365,7 @@ var_cell_t *
connection_or_compute_authenticate_cell_body(or_connection_t *conn,
const int authtype,
crypto_pk_t *signing_key,
ed25519_keypair_t *ed_signing_key,
const ed25519_keypair_t *ed_signing_key,
int server)
{
auth1_t *auth = NULL;
@ -2559,16 +2594,16 @@ connection_or_send_authenticate_cell,(or_connection_t *conn, int authtype))
log_warn(LD_BUG, "Can't compute authenticate cell: no client auth key");
return -1;
}
if (authtype != AUTHTYPE_RSA_SHA256_TLSSECRET) {
if (! authchallenge_type_is_supported(authtype)) {
log_warn(LD_BUG, "Tried to send authenticate cell with unknown "
"authentication type %d", authtype);
return -1;
}
cell = connection_or_compute_authenticate_cell_body(conn,
AUTHTYPE_RSA_SHA256_TLSSECRET,
authtype,
pk,
NULL,
get_current_auth_keypair(),
0 /* not server */);
if (! cell) {
log_warn(LD_BUG, "Unable to compute authenticate cell!");

5
src/or/connection_or.h
View File

@ -88,10 +88,13 @@ int connection_or_send_versions(or_connection_t *conn, int v3_plus);
MOCK_DECL(int,connection_or_send_netinfo,(or_connection_t *conn));
int connection_or_send_certs_cell(or_connection_t *conn);
int connection_or_send_auth_challenge_cell(or_connection_t *conn);
int authchallenge_type_is_supported(uint16_t challenge_type);
int authchallenge_type_is_better(uint16_t challenge_type_a,
uint16_t challenge_type_b);
var_cell_t *connection_or_compute_authenticate_cell_body(or_connection_t *conn,
const int authtype,
crypto_pk_t *signing_key,
ed25519_keypair_t *ed_signing_key,
const ed25519_keypair_t *ed_signing_key,
int server);
MOCK_DECL(int,connection_or_send_authenticate_cell,
(or_connection_t *conn, int type));

14
src/test/test_link_handshake.c
View File

@ -484,15 +484,15 @@ test_link_handshake_send_authchallenge(void *arg)
cell1 = mock_got_var_cell;
tt_int_op(0, ==, connection_or_send_auth_challenge_cell(c1));
cell2 = mock_got_var_cell;
tt_int_op(36, ==, cell1->payload_len);
tt_int_op(36, ==, cell2->payload_len);
tt_int_op(40, ==, cell1->payload_len);
tt_int_op(40, ==, cell2->payload_len);
tt_int_op(0, ==, cell1->circ_id);
tt_int_op(0, ==, cell2->circ_id);
tt_int_op(CELL_AUTH_CHALLENGE, ==, cell1->command);
tt_int_op(CELL_AUTH_CHALLENGE, ==, cell2->command);
tt_mem_op("\x00\x01\x00\x01", ==, cell1->payload + 32, 4);
tt_mem_op("\x00\x01\x00\x01", ==, cell2->payload + 32, 4);
tt_mem_op("\x00\x03\x00\x01\x00\x02\x00\x03", ==, cell1->payload + 32, 8);
tt_mem_op("\x00\x03\x00\x01\x00\x02\x00\x03", ==, cell2->payload + 32, 8);
tt_mem_op(cell1->payload, !=, cell2->payload, 32);
done:
@ -909,8 +909,8 @@ AUTHENTICATE_FAIL(noidcert,
tor_x509_cert_free(d->c2->handshake_state->certs->id_cert);
d->c2->handshake_state->certs->id_cert = NULL)
AUTHENTICATE_FAIL(noauthcert,
require_failure_message = "We never got an authentication "
"certificate";
require_failure_message = "We never got an RSA "
"authentication certificate";
tor_x509_cert_free(d->c2->handshake_state->certs->auth_cert);
d->c2->handshake_state->certs->auth_cert = NULL)
AUTHENTICATE_FAIL(tooshort,
@ -936,7 +936,7 @@ AUTHENTICATE_FAIL(badcontent,
"cell body was not as expected";
d->cell->payload[10] ^= 0xff)
AUTHENTICATE_FAIL(badsig_1,
require_failure_message = "Signature wasn't valid";
require_failure_message = "RSA signature wasn't valid";
d->cell->payload[d->cell->payload_len - 5] ^= 0xff)
#define TEST(name, flags) \