From mboxrd@z Thu Jan 1 00:00:00 1970 Received: by passt.top (Postfix, from userid 1000) id 50D0B5A027C; Fri, 16 Aug 2024 09:39:18 +0200 (CEST) From: Stefano Brivio To: passt-dev@passt.top Subject: [PATCH v3 6/7] pasta: Disable neighbour solicitations on device up to prevent DAD Date: Fri, 16 Aug 2024 09:39:17 +0200 Message-ID: <20240816073918.1483136-7-sbrivio@redhat.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240816073918.1483136-1-sbrivio@redhat.com> References: <20240816073918.1483136-1-sbrivio@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Message-ID-Hash: 6VRA5KCOVJOWFB3EJTVSGC6YZJYLLVZH X-Message-ID-Hash: 6VRA5KCOVJOWFB3EJTVSGC6YZJYLLVZH 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 --- netlink.c | 22 ++++++++++++---------- pasta.c | 11 ++++++++++- 2 files changed, 22 insertions(+), 11 deletions(-) diff --git a/netlink.c b/netlink.c index 06a3816..9592b1b 100644 --- a/netlink.c +++ b/netlink.c @@ -689,11 +689,10 @@ int nl_addr_set_ll_nodad(int s, unsigned int ifi) .ifa.ifa_family = AF_INET6, .ifa.ifa_index = ifi, }; - unsigned ll_addrs = 0; + uint32_t seq, last_seq = 0; + ssize_t status, ret = 0; struct nlmsghdr *nh; char buf[NLBUFSIZ]; - ssize_t status; - uint32_t seq; seq = nl_send(s, &req, RTM_GETADDR, NLM_F_DUMP, sizeof(req)); nl_foreach_oftype(nh, status, s, buf, seq, RTM_NEWADDR) { @@ -713,19 +712,22 @@ int nl_addr_set_ll_nodad(int s, unsigned int ifi) *(uint32_t *)RTA_DATA(rta) |= IFA_F_NODAD; } - nl_send(s, nh, RTM_NEWADDR, NLM_F_REPLACE, nh->nlmsg_len); - ll_addrs++; + last_seq = nl_send(s, nh, RTM_NEWADDR, NLM_F_REPLACE, + nh->nlmsg_len); } if (status < 0) - return status; + ret = status; - seq += ll_addrs; + for (seq = seq + 1; seq <= last_seq; seq++) { + nl_foreach(nh, status, s, buf, seq) + warn("netlink: Unexpected response message"); - nl_foreach(nh, status, s, buf, seq) - warn("netlink: Unexpected response message"); + if (!ret && status < 0) + ret = status; + } - return status; + return ret; } /** 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