Re: PMTUD broken inside network namespace with multipath routing

On 9/1/20 4:40 AM, mastertheknife wrote:

P.S: while reading the relevant code in the kernel, i think i spotted
some mistake in net/ipv4/route.c, in function "update_or_create_fnhe".
It looks like it loops over all the exceptions for the nexthop entry,
but always overwriting the first (and only) entry, so effectively only
1 exception can exist per nexthop entry.
Line 678:
"if (fnhe) {"
Should probably be:
"if (fnhe && fnhe->fnhe_daddr == daddr) {"

Right above that line is:

        for (fnhe = rcu_dereference(hash->chain); fnhe;
             fnhe = rcu_dereference(fnhe->fnhe_next)) {
                if (fnhe->fnhe_daddr == daddr)
                        break;
                depth++;
        }

so fnhe is set based on daddr match.