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wg: Verify or send cookie challenge before looking up session. 

This step doesn't depend on the session, so let's avoid touching the
session state until we've passed it.
This commit is contained in:
riastradh 2020-08-31 20:29:14 +00:00
parent f25326ab88
commit 375c658faf
1 changed files with 36 additions and 36 deletions
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72
sys/net/if_wg.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: if_wg.c,v 1.44 2020/08/31 20:27:06 riastradh Exp $ */
/* $NetBSD: if_wg.c,v 1.45 2020/08/31 20:29:14 riastradh Exp $ */
/*
* Copyright (C) Ryota Ozaki <ozaki.ryota@gmail.com>
@ -41,7 +41,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: if_wg.c,v 1.44 2020/08/31 20:27:06 riastradh Exp $");
__KERNEL_RCSID(0, "$NetBSD: if_wg.c,v 1.45 2020/08/31 20:29:14 riastradh Exp $");
#ifdef _KERNEL_OPT
#include "opt_inet.h"
@ -1399,6 +1399,40 @@ wg_handle_msg_init(struct wg_softc *wg, const struct wg_msg_init *wgmi,
return;
}
if (__predict_false(wg_is_underload(wg, wgp, WG_MSG_TYPE_INIT))) {
WG_TRACE("under load");
/*
* [W] 5.3: Denial of Service Mitigation & Cookies
* "the responder, ..., and when under load may reject messages
* with an invalid msg.mac2. If the responder receives a
* message with a valid msg.mac1 yet with an invalid msg.mac2,
* and is under load, it may respond with a cookie reply
* message"
*/
uint8_t zero[WG_MAC_LEN] = {0};
if (consttime_memequal(wgmi->wgmi_mac2, zero, sizeof(zero))) {
WG_TRACE("sending a cookie message: no cookie included");
(void)wg_send_cookie_msg(wg, wgp, wgmi->wgmi_sender,
wgmi->wgmi_mac1, src);
goto out_wgp;
}
if (!wgp->wgp_last_sent_cookie_valid) {
WG_TRACE("sending a cookie message: no cookie sent ever");
(void)wg_send_cookie_msg(wg, wgp, wgmi->wgmi_sender,
wgmi->wgmi_mac1, src);
goto out_wgp;
}
uint8_t mac2[WG_MAC_LEN];
wg_algo_mac(mac2, sizeof(mac2), wgp->wgp_last_sent_cookie,
WG_COOKIE_LEN, (const uint8_t *)wgmi,
offsetof(struct wg_msg_init, wgmi_mac2), NULL, 0);
if (!consttime_memequal(mac2, wgmi->wgmi_mac2, sizeof(mac2))) {
WG_DLOG("mac2 is invalid\n");
goto out_wgp;
}
WG_TRACE("under load, but continue to sending");
}
wgs = wg_lock_unstable_session(wgp);
if (wgs->wgs_state == WGS_STATE_DESTROYING) {
/*
@ -1425,40 +1459,6 @@ wg_handle_msg_init(struct wg_softc *wg, const struct wg_msg_init *wgmi,
wg_get_session(wgs, &psref_session);
mutex_exit(wgs->wgs_lock);
if (__predict_false(wg_is_underload(wg, wgp, WG_MSG_TYPE_INIT))) {
WG_TRACE("under load");
/*
* [W] 5.3: Denial of Service Mitigation & Cookies
* "the responder, ..., and when under load may reject messages
* with an invalid msg.mac2. If the responder receives a
* message with a valid msg.mac1 yet with an invalid msg.mac2,
* and is under load, it may respond with a cookie reply
* message"
*/
uint8_t zero[WG_MAC_LEN] = {0};
if (consttime_memequal(wgmi->wgmi_mac2, zero, sizeof(zero))) {
WG_TRACE("sending a cookie message: no cookie included");
(void)wg_send_cookie_msg(wg, wgp, wgmi->wgmi_sender,
wgmi->wgmi_mac1, src);
goto out;
}
if (!wgp->wgp_last_sent_cookie_valid) {
WG_TRACE("sending a cookie message: no cookie sent ever");
(void)wg_send_cookie_msg(wg, wgp, wgmi->wgmi_sender,
wgmi->wgmi_mac1, src);
goto out;
}
uint8_t mac2[WG_MAC_LEN];
wg_algo_mac(mac2, sizeof(mac2), wgp->wgp_last_sent_cookie,
WG_COOKIE_LEN, (const uint8_t *)wgmi,
offsetof(struct wg_msg_init, wgmi_mac2), NULL, 0);
if (!consttime_memequal(mac2, wgmi->wgmi_mac2, sizeof(mac2))) {
WG_DLOG("mac2 is invalid\n");
goto out;
}
WG_TRACE("under load, but continue to sending");
}
/* [N] 2.2: "ss" */
/* Ci, k := KDF2(Ci, DH(Si^priv, Sr^pub)) */
wg_algo_dh_kdf(ckey, cipher_key, wg->wg_privkey, wgp->wgp_pubkey);