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gossip: send error messages on grossly malformed channel_update.
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As per BOLT #7.

We don't do this for channel_update which are queued because the
channel_announcement is pending though.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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@rustyrussell
rustyrussell committed Mar 8, 2018
1 parent ef82f2b commit 084f0bc
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Showing 3 changed files with 63 additions and 24 deletions.
19 changes: 15 additions & 4 deletions gossipd/gossip.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -506,7 +506,9 @@ static void handle_gossip_msg(struct peer *peer, u8 *msg)
break;

case WIRE_CHANNEL_UPDATE:
handle_channel_update(rstate, msg);
err = handle_channel_update(rstate, msg);
if (err)
queue_peer_msg(peer, take(err));
break;
}
}
Expand Down Expand Up @@ -1309,7 +1311,7 @@ static void gossip_send_keepalive_update(struct routing_state *rstate,
u32 timestamp, fee_base_msat, fee_proportional_millionths;
u64 htlc_minimum_msat;
u16 flags, cltv_expiry_delta;
u8 *update, *msg;
u8 *update, *msg, *err;

/* Parse old update */
if (!fromwire_channel_update(
Expand Down Expand Up @@ -1344,7 +1346,11 @@ static void gossip_send_keepalive_update(struct routing_state *rstate,
status_trace("Sending keepalive channel_update for %s",
type_to_string(tmpctx, struct short_channel_id, &scid));

handle_channel_update(rstate, update);
err = handle_channel_update(rstate, update);
if (err)
status_failed(STATUS_FAIL_INTERNAL_ERROR,
"rejected keepalive channel_update: %s",
tal_hex(trc, err));
tal_free(tmpctx);

}
Expand Down Expand Up @@ -1838,6 +1844,7 @@ static struct io_plan *handle_disable_channel(struct io_conn *conn,
struct bitcoin_blkid chain_hash;
secp256k1_ecdsa_signature sig;
u64 htlc_minimum_msat;
u8 *err;

if (!fromwire_gossip_disable_channel(msg, &scid, &direction, &active) ) {
status_unusual("Unable to parse %s",
Expand Down Expand Up @@ -1902,7 +1909,11 @@ static struct io_plan *handle_disable_channel(struct io_conn *conn,
strerror(errno));
}

handle_channel_update(daemon->rstate, msg);
err = handle_channel_update(daemon->rstate, msg);
if (err)
status_failed(STATUS_FAIL_INTERNAL_ERROR,
"rejected disabling channel_update: %s",
tal_hex(trc, err));

fail:
tal_free(tmpctx);
Expand Down
64 changes: 45 additions & 19 deletions gossipd/routing.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -451,16 +451,28 @@ find_route(const tal_t *ctx, struct routing_state *rstate,
}

/* Verify the signature of a channel_update message */
static bool check_channel_update(const struct pubkey *node_key,
const secp256k1_ecdsa_signature *node_sig,
const u8 *update)
static u8 *check_channel_update(const tal_t *ctx,
const struct pubkey *node_key,
const secp256k1_ecdsa_signature *node_sig,
const u8 *update)
{
/* 2 byte msg type + 64 byte signatures */
int offset = 66;
struct sha256_double hash;
sha256_double(&hash, update + offset, tal_len(update) - offset);

return check_signed_hash(&hash, node_sig, node_key);
if (!check_signed_hash(&hash, node_sig, node_key))
return towire_errorfmt(ctx, NULL,
"Bad signature for %s hash %s"
" on channel_update %s",
type_to_string(ctx,
secp256k1_ecdsa_signature,
node_sig),
type_to_string(ctx,
struct sha256_double,
&hash),
tal_hex(ctx, update));
return NULL;
}

static u8 *check_channel_announcement(const tal_t *ctx,
Expand Down Expand Up @@ -793,10 +805,11 @@ bool handle_pending_cannouncement(struct routing_state *rstate,
pubkey_eq(&pending->node_id_2, &rstate->local_id);

/* Did we have an update waiting? If so, apply now. */
/* FIXME: We don't remember who sent us updates, so we can't error them */
if (pending->updates[0])
handle_channel_update(rstate, pending->updates[0]);
tal_free(handle_channel_update(rstate, pending->updates[0]));
if (pending->updates[1])
handle_channel_update(rstate, pending->updates[1]);
tal_free(handle_channel_update(rstate, pending->updates[1]));

process_pending_node_announcement(rstate, &pending->node_id_1);
process_pending_node_announcement(rstate, &pending->node_id_2);
Expand Down Expand Up @@ -860,7 +873,7 @@ void set_connection_values(struct chan *chan,
}
}

void handle_channel_update(struct routing_state *rstate, const u8 *update)
u8 *handle_channel_update(struct routing_state *rstate, const u8 *update)
{
u8 *serialized;
struct half_chan *c;
Expand All @@ -877,15 +890,19 @@ void handle_channel_update(struct routing_state *rstate, const u8 *update)
struct chan *chan;
u8 direction;
size_t len = tal_len(update);
u8 *err;

serialized = tal_dup_arr(tmpctx, u8, update, len, 0);
if (!fromwire_channel_update(serialized, &signature,
&chain_hash, &short_channel_id,
&timestamp, &flags, &expiry,
&htlc_minimum_msat, &fee_base_msat,
&fee_proportional_millionths)) {
err = towire_errorfmt(rstate, NULL,
"Malformed channel_update %s",
tal_hex(tmpctx, serialized));
tal_free(tmpctx);
return;
return err;
}
direction = flags & 0x1;

Expand All @@ -899,7 +916,7 @@ void handle_channel_update(struct routing_state *rstate, const u8 *update)
type_to_string(tmpctx, struct bitcoin_blkid,
&chain_hash));
tal_free(tmpctx);
return;
return NULL;
}

chan = get_channel(rstate, &short_channel_id);
Expand Down Expand Up @@ -933,11 +950,20 @@ void handle_channel_update(struct routing_state *rstate, const u8 *update)
return;
}

if (!check_channel_update(&chan->nodes[direction]->id,
&signature, serialized)) {
status_trace("Signature verification failed.");
err = check_channel_update(rstate, &chan->nodes[direction]->id,
&signature, serialized);
if (err) {
/* BOLT #7:
*
* - if `signature` is not a valid signature, using `node_id`
* of the double-SHA256 of the entire message following the
* `signature` field (including unknown fields following
* `fee_proportional_millionths`):
* - MUST NOT process the message further.
* - SHOULD fail the connection.
*/
tal_free(tmpctx);
return;
return err;
}

status_trace("Received channel_update for channel %s(%d) now %s",
Expand Down Expand Up @@ -1299,6 +1325,7 @@ void routing_failure(struct routing_state *rstate,
* channel_update is newer it will be
* reactivated. */
if (failcode & UPDATE) {
u8 *err;
if (tal_len(channel_update) == 0) {
/* Suppress UNUSUAL log if local failure */
if (structeq(&erring_node_pubkey->pubkey,
Expand All @@ -1310,15 +1337,14 @@ void routing_failure(struct routing_state *rstate,
(int) failcode);
goto out;
}
t = fromwire_peektype(channel_update);
if (t != WIRE_CHANNEL_UPDATE) {
err = handle_channel_update(rstate, channel_update);
if (err) {
status_unusual("routing_failure: "
"not a channel_update. "
"type: %d",
(int) t);
"bad channel_update %s",
sanitize_error(err, err, NULL));
tal_free(err);
goto out;
}
handle_channel_update(rstate, channel_update);
} else {
if (tal_len(channel_update) != 0)
status_unusual("routing_failure: "
Expand Down
4 changes: 3 additions & 1 deletion gossipd/routing.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -212,7 +212,9 @@ u8 *handle_channel_announcement(struct routing_state *rstate,
bool handle_pending_cannouncement(struct routing_state *rstate,
const struct short_channel_id *scid,
const u8 *txscript);
void handle_channel_update(struct routing_state *rstate, const u8 *update);

/* Returns NULL if all OK, otherwise an error for the peer which sent. */
u8 *handle_channel_update(struct routing_state *rstate, const u8 *update);

/* Returns NULL if all OK, otherwise an error for the peer which sent. */
u8 *handle_node_announcement(struct routing_state *rstate, const u8 *node);
Expand Down

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