From mboxrd@z Thu Jan 1 00:00:00 1970 Received: by passt.top (Postfix, from userid 1000) id 2BF895A027C; Thu, 15 Aug 2024 10:36:49 +0200 (CEST) From: Stefano Brivio To: passt-dev@passt.top Subject: [PATCH v2 6/7] pasta: Disable neighbour solicitations on device up to prevent DAD Date: Thu, 15 Aug 2024 10:36:48 +0200 Message-ID: <20240815083649.4188007-7-sbrivio@redhat.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240815083649.4188007-1-sbrivio@redhat.com> References: <20240815083649.4188007-1-sbrivio@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Message-ID-Hash: OVKKZ53IEDVRNZVTMQUWFBQ4QYWTMLDX X-Message-ID-Hash: OVKKZ53IEDVRNZVTMQUWFBQ4QYWTMLDX X-MailFrom: sbrivio@passt.top X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: David Gibson , Paul Holzinger X-Mailman-Version: 3.3.8 Precedence: list List-Id: Development discussion and patches for passt Archived-At: Archived-At: List-Archive: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: As soon as we the kernel notifier for IPv6 address configuration (addrconf_notify()) sees that we bring the target interface up (NETDEV_UP), it will schedule duplicate address detection, so, by itself, setting the nodad flag later is useless, because that won't stop a detection that's already in progress. However, if we disable neighbour solicitations with IFF_NOARP (which is a misnomer for IPv6 interfaces, but there's no possibility of mixing things up), the notifier will not trigger DAD, because it can't be done, of course, without neighbour solicitations. Set IFF_NOARP as we bring up the device, and drop it after we had a chance to set the nodad attribute on the link. Signed-off-by: Stefano Brivio Reviewed-by: David Gibson --- pasta.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/pasta.c b/pasta.c index e8883bd..1142f03 100644 --- a/pasta.c +++ b/pasta.c @@ -303,10 +303,15 @@ void pasta_ns_conf(struct ctx *c) strerror(-rc)); if (c->pasta_conf_ns) { + unsigned int flags = IFF_UP; + if (c->mtu != -1) nl_link_set_mtu(nl_sock_ns, c->pasta_ifi, c->mtu); - nl_link_set_flags(nl_sock_ns, c->pasta_ifi, IFF_UP, IFF_UP); + if (c->ifi6) /* Avoid duplicate address detection on link up */ + flags |= IFF_NOARP; + + nl_link_set_flags(nl_sock_ns, c->pasta_ifi, flags, flags); if (c->ifi4) { if (c->ip4.no_copy_addrs) { @@ -353,6 +358,10 @@ void pasta_ns_conf(struct ctx *c) strerror(-rc)); } + /* We dodged DAD: re-enable neighbour solicitations */ + nl_link_set_flags(nl_sock_ns, c->pasta_ifi, + 0, IFF_NOARP); + if (c->ip6.no_copy_addrs) { rc = nl_addr_set(nl_sock_ns, c->pasta_ifi, AF_INET6, &c->ip6.addr, 64); -- 2.43.0