From: sthen Date: Sun, 21 Mar 2021 18:13:59 +0000 (+0000) Subject: wg(4): fix race between tx/rx handshakes, from Matt Dunwoodie, ok mpi@ X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=1507f9071270bfba00c7a3f5c192590e1442b199;p=openbsd wg(4): fix race between tx/rx handshakes, from Matt Dunwoodie, ok mpi@ "There is a race between sending/receiving handshake packets. This occurs if we consume an initiation, then send an initiation prior to replying to the consumed initiation. In particular, when consuming an initiation, we don't generate the index until creating the response (which is incorrect). If we attempt to create an initiation between these processes, we drop any outstanding handshake which in this case has index 0 as set when consuming the initiation. The fix attached is to generate the index when consuming the initiation so that any spurious initiation creation can drop a valid index. The patch also consolidates setting fields on the handshake." --- diff --git a/sys/net/wg_noise.c b/sys/net/wg_noise.c index 86f7823cc83..47552229b8a 100644 --- a/sys/net/wg_noise.c +++ b/sys/net/wg_noise.c @@ -1,4 +1,4 @@ -/* $OpenBSD: wg_noise.c,v 1.4 2020/12/09 05:53:33 tb Exp $ */ +/* $OpenBSD: wg_noise.c,v 1.5 2021/03/21 18:13:59 sthen Exp $ */ /* * Copyright (C) 2015-2020 Jason A. Donenfeld . All Rights Reserved. * Copyright (C) 2019-2020 Matt Dunwoodie @@ -299,9 +299,6 @@ noise_consume_initiation(struct noise_local *l, struct noise_remote **rp, NOISE_TIMESTAMP_LEN + NOISE_AUTHTAG_LEN, key, hs.hs_hash) != 0) goto error; - hs.hs_state = CONSUMED_INITIATION; - hs.hs_local_index = 0; - hs.hs_remote_index = s_idx; memcpy(hs.hs_e, ue, NOISE_PUBLIC_KEY_LEN); /* We have successfully computed the same results, now we ensure that @@ -321,6 +318,9 @@ noise_consume_initiation(struct noise_local *l, struct noise_remote **rp, /* Ok, we're happy to accept this initiation now */ noise_remote_handshake_index_drop(r); + hs.hs_state = CONSUMED_INITIATION; + hs.hs_local_index = noise_remote_handshake_index_get(r); + hs.hs_remote_index = s_idx; r->r_handshake = hs; *rp = r; ret = 0; @@ -369,7 +369,6 @@ noise_create_response(struct noise_remote *r, uint32_t *s_idx, uint32_t *r_idx, noise_msg_encrypt(en, NULL, 0, key, hs->hs_hash); hs->hs_state = CREATED_RESPONSE; - hs->hs_local_index = noise_remote_handshake_index_get(r); *r_idx = hs->hs_remote_index; *s_idx = hs->hs_local_index; ret = 0;