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lightningd: check channel_announcement signatures we get from peer.

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We hoise check_signed_hash_nodeid from gossipd's internals, into common/.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell 2024-01-31 13:46:18 +10:30
parent 7bdbb62b09
commit 3508331fc4
7 changed files with 103 additions and 16 deletions
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11
common/node_id.c
View file

@ -1,5 +1,6 @@
#include "config.h"
#include <assert.h>
#include <bitcoin/signature.h>
#include <ccan/array_size/array_size.h>
#include <ccan/mem/mem.h>
#include <ccan/str/hex/hex.h>
@ -66,3 +67,13 @@ void towire_node_id(u8 **pptr, const struct node_id *id)
#endif
towire(pptr, id->k, sizeof(id->k));
}
bool check_signed_hash_nodeid(const struct sha256_double *hash,
const secp256k1_ecdsa_signature *signature,
const struct node_id *id)
{
struct pubkey key;
return pubkey_from_node_id(&key, id)
&& check_signed_hash(hash, signature, &key);
}

16
common/node_id.h
View file

@ -7,6 +7,8 @@
#include <ccan/htable/htable_type.h>
#include <common/pseudorand.h>
struct sha256_double;
struct node_id {
u8 k[PUBKEY_CMPR_LEN];
};
@ -63,4 +65,18 @@ static inline size_t node_id_hash(const struct node_id *id)
{
return siphash24(siphash_seed(), id->k, sizeof(id->k));
}
/**
* check_signed_hash_nodeid - check a raw secp256k1 signature.
* @h: hash which was signed.
* @signature: signature.
* @id: node_id corresponding to private key used to sign.
*
* Returns true if the id, hash and signature are correct. Changing any
* one of these will make it fail.
*/
bool check_signed_hash_nodeid(const struct sha256_double *hash,
const secp256k1_ecdsa_signature *signature,
const struct node_id *id);
#endif /* LIGHTNING_COMMON_NODE_ID_H */

11
gossipd/routing.c
View file

@ -618,17 +618,6 @@ struct chan *new_chan(struct routing_state *rstate,
return chan;
}
/* Checks that key is valid, and signed this hash */
static bool check_signed_hash_nodeid(const struct sha256_double *hash,
const secp256k1_ecdsa_signature *signature,
const struct node_id *id)
{
struct pubkey key;
return pubkey_from_node_id(&key, id)
&& check_signed_hash(hash, signature, &key);
}
/* Verify the signature of a channel_update message */
static u8 *check_channel_update(const tal_t *ctx,
const struct node_id *node_id,

22
lightningd/channel_gossip.c
View file

@ -351,6 +351,21 @@ static void stash_remote_announce_sigs(struct channel *channel,
const secp256k1_ecdsa_signature *bitcoin_sig)
{
struct channel_gossip *cg = channel->channel_gossip;
const char *err;
/* BOLT #7:
* - if the `node_signature` OR the `bitcoin_signature` is NOT correct:
* - MAY send a `warning` and close the connection, or send an
* `error` and fail the channel.
*/
err = check_announce_sigs(channel, scid, node_sig, bitcoin_sig);
if (err) {
channel_fail_transient(channel, true,
"Bad gossip announcement_signatures for scid %s: %s",
short_channel_id_to_str(tmpctx, &scid),
err);
return;
}
tal_free(cg->remote_sigs);
cg->remote_sigs = tal(cg, struct remote_announce_sigs);
@ -375,7 +390,6 @@ static bool apply_remote_sigs(struct channel *channel)
return false;
}
/* FIXME: check sigs are valid! */
wallet_announcement_save(channel->peer->ld->wallet,
channel->dbid,
&cg->remote_sigs->node_sig,
@ -397,7 +411,7 @@ static void send_channel_announce_sigs(struct channel *channel)
if (!channel_state_can_add_htlc(channel->state))
return;
ca = create_channel_announcement(tmpctx, channel,
ca = create_channel_announcement(tmpctx, channel, *channel->scid,
NULL, NULL, NULL, NULL);
msg = hsm_sync_req(tmpctx, ld,
@ -453,7 +467,7 @@ static void send_channel_announcement(struct channel *channel)
const u8 *ca, *msg;
struct channel_gossip *cg = channel->channel_gossip;
ca = create_channel_announcement(tmpctx, channel,
ca = create_channel_announcement(tmpctx, channel, *channel->scid,
NULL, NULL,
&cg->remote_sigs->node_sig,
&cg->remote_sigs->bitcoin_sig);
@ -471,7 +485,7 @@ static void send_channel_announcement(struct channel *channel)
if (!ld->gossip)
return;
ca = create_channel_announcement(tmpctx, channel,
ca = create_channel_announcement(tmpctx, channel, *channel->scid,
&local_node_sig,
&local_bitcoin_sig,
&cg->remote_sigs->node_sig,

36
lightningd/gossip_generation.c
View file

@ -51,6 +51,7 @@ static void copysig_or_zero(secp256k1_ecdsa_signature *dst,
u8 *create_channel_announcement(const tal_t *ctx,
const struct channel *channel,
struct short_channel_id scid,
const secp256k1_ecdsa_signature *local_node_signature,
const secp256k1_ecdsa_signature *local_bitcoin_signature,
const secp256k1_ecdsa_signature *remote_node_signature,
@ -72,7 +73,7 @@ u8 *create_channel_announcement(const tal_t *ctx,
node_id[REMOTE] = channel->peer->id;
funding_pubkey[LOCAL] = channel->local_funding_pubkey;
funding_pubkey[REMOTE] = channel->channel_info.remote_fundingkey;
return create_channel_announcement_dir(ctx, features, *channel->scid,
return create_channel_announcement_dir(ctx, features, scid,
node_signature, bitcoin_signature, node_id, funding_pubkey);
}
@ -205,3 +206,36 @@ bool channel_update_details(const u8 *channel_update,
*enabled = !(channel_flags & ROUTING_FLAGS_DISABLED);
return true;
}
const char *check_announce_sigs(const struct channel *channel,
struct short_channel_id scid,
const secp256k1_ecdsa_signature *remote_node_signature,
const secp256k1_ecdsa_signature *remote_bitcoin_signature)
{
struct sha256_double hash;
const u8 *cannounce;
cannounce = create_channel_announcement(tmpctx, channel, scid,
NULL, NULL, NULL, NULL);
/* BOLT #7:
*
* - MUST compute the double-SHA256 hash `h` of the message, beginning
* at offset 256, up to the end of the message.
* - Note: the hash skips the 4 signatures but hashes the rest of the
* message, including any future fields appended to the end.
*/
/* First two bytes are the msg type */
int offset = 258;
sha256_double(&hash, cannounce + offset, tal_count(cannounce) - offset);
if (!check_signed_hash_nodeid(&hash, remote_node_signature,
&channel->peer->id))
return "invalid node_signature";
if (!check_signed_hash(&hash, remote_bitcoin_signature,
&channel->channel_info.remote_fundingkey))
return "invalid bitcoin_signature";
return NULL;
}

16
lightningd/gossip_generation.h
View file

@ -10,6 +10,7 @@ struct channel;
* create_channel_announcement: create a channel_announcement message
* @ctx: the tal context to allocate return from
* @channel: the channel to announce
* @scid: channel->scid
* @local_node_signature: optional local node signature
* @local_bitcoin_signature: optional local node signature
* @remote_node_signature: optional peer node signature
@ -20,6 +21,7 @@ struct channel;
*/
u8 *create_channel_announcement(const tal_t *ctx,
const struct channel *channel,
struct short_channel_id scid,
const secp256k1_ecdsa_signature *local_node_signature,
const secp256k1_ecdsa_signature *local_bitcoin_signature,
const secp256k1_ecdsa_signature *remote_node_signature,
@ -61,4 +63,18 @@ bool channel_update_details(const u8 *channel_update,
u32 *timestamp,
bool *enabled);
/**
* check_announce_sigs: check that signatures are correct for this scid
* @channel: the channel (for peer's id / bitcoin key and the channel features)
* @scid: the short_channel_id it's proposing
* @remote_node_signature: node signature
* @remote_bitcoin_signature: bitcoin signature
*
* Returns a string literal if one signature is bad.
*/
const char *check_announce_sigs(const struct channel *channel,
struct short_channel_id scid,
const secp256k1_ecdsa_signature *remote_node_signature,
const secp256k1_ecdsa_signature *remote_bitcoin_signature);
#endif /* LIGHTNING_LIGHTNINGD_GOSSIP_GENERATION_H */

7
wallet/test/run-wallet.c
View file

@ -107,6 +107,12 @@ void channeld_tell_depth(struct channel *channel UNNEEDED,
const struct bitcoin_txid *txid UNNEEDED,
u32 depth UNNEEDED)
{ fprintf(stderr, "channeld_tell_depth called!\n"); abort(); }
/* Generated stub for check_announce_sigs */
const char *check_announce_sigs(const struct channel *channel UNNEEDED,
struct short_channel_id scid UNNEEDED,
const secp256k1_ecdsa_signature *remote_node_signature UNNEEDED,
const secp256k1_ecdsa_signature *remote_bitcoin_signature UNNEEDED)
{ fprintf(stderr, "check_announce_sigs called!\n"); abort(); }
/* Generated stub for cmd_id_from_close_command */
const char *cmd_id_from_close_command(const tal_t *ctx UNNEEDED,
struct lightningd *ld UNNEEDED, struct channel *channel UNNEEDED)
@ -174,6 +180,7 @@ struct anchor_details *create_anchor_details(const tal_t *ctx UNNEEDED,
/* Generated stub for create_channel_announcement */
u8 *create_channel_announcement(const tal_t *ctx UNNEEDED,
const struct channel *channel UNNEEDED,
struct short_channel_id scid UNNEEDED,
const secp256k1_ecdsa_signature *local_node_signature UNNEEDED,
const secp256k1_ecdsa_signature *local_bitcoin_signature UNNEEDED,
const secp256k1_ecdsa_signature *remote_node_signature UNNEEDED,