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netlink: Use IFA_F_NODAD also while duplicating addresses from the host

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...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@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
This commit is contained in:
Stefano Brivio 2024-04-26 00:04:53 +02:00
parent bfc83b54c4
commit d03c4e2020
1 changed files with 6 additions and 0 deletions
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6
netlink.c
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@ -804,6 +804,8 @@ int nl_addr_dup(int s_src, unsigned int ifi_src,
continue; continue;
ifa->ifa_index = ifi_dst; 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); for (rta = IFA_RTA(ifa), na = IFA_PAYLOAD(nh); RTA_OK(rta, na);
rta = RTA_NEXT(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 || if (rta->rta_type == IFA_LABEL ||
rta->rta_type == IFA_CACHEINFO) rta->rta_type == IFA_CACHEINFO)
rta->rta_type = IFA_UNSPEC; 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, rc = nl_do(s_dst, nh, RTM_NEWADDR,