On Fri, Apr 26, 2024 at 12:10:15AM +0200, Stefano Brivio wrote:...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 <sbrivio(a)redhat.com>Reviewed-by: David Gibson <david(a)gibson.dropbear.id.au>--- 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,-- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson