From d03c4e20202b9546b2b233a2ff98cb3b3395b8d9 Mon Sep 17 00:00:00 2001 From: Stefano Brivio Date: Fri, 26 Apr 2024 00:04:53 +0200 Subject: [PATCH] netlink: Use IFA_F_NODAD also while duplicating addresses from the host ...not just for a single set address (legacy operation with --no-copy-addrs). I forgot to add this to nl_addr_dup(). Note that we can have two version of flags: the 8-bit ifa_flags in ifaddrmsg, and the newer 32-bit version as IFA_FLAGS attribute, which is given priority if present. Make sure IFA_F_NODAD is set in both. Without this, a Podman user reports, something on the lines of: pasta --config-net -- ping -c1 -6 passt.top would fail as the kernel would start Duplicate Address Detection once we configure the address, which can't really work (and doesn't make sense) in this case. Signed-off-by: Stefano Brivio Reviewed-by: David Gibson --- netlink.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/netlink.c b/netlink.c index 447fea2..b3897e6 100644 --- a/netlink.c +++ b/netlink.c @@ -804,6 +804,8 @@ int nl_addr_dup(int s_src, unsigned int ifi_src, continue; ifa->ifa_index = ifi_dst; + /* Same as nl_addr_set(), but here it's more than a default */ + ifa->ifa_flags |= IFA_F_NODAD; for (rta = IFA_RTA(ifa), na = IFA_PAYLOAD(nh); RTA_OK(rta, na); rta = RTA_NEXT(rta, na)) { @@ -811,6 +813,10 @@ int nl_addr_dup(int s_src, unsigned int ifi_src, if (rta->rta_type == IFA_LABEL || rta->rta_type == IFA_CACHEINFO) rta->rta_type = IFA_UNSPEC; + + /* If 32-bit flags are used, add IFA_F_NODAD there */ + if (rta->rta_type == IFA_FLAGS) + *(uint32_t *)RTA_DATA(rta) |= IFA_F_NODAD; } rc = nl_do(s_dst, nh, RTM_NEWADDR,