netdev - restoring IP multicast addresses when restarting the interface.

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20120420212533.78903e3a@asterix.rh>
Date:	Fri, 20 Apr 2012 21:25:33 -0300
From:	Flavio Leitner <fbl@...hat.com>
To:	netdev <netdev@...r.kernel.org>
Cc:	Herbert Xu <herbert@...dor.hengli.com.au>
Subject: restoring IP multicast addresses when restarting the interface.

Hello folks,

I was told that ntp in multicast mode was not working if you
restart the interface (ifdown <iface> ; ifup <iface) on an
older kernel.

It seemed obvious to me, but when I tried to reproduce this
upstream (last kernel of today), I noticed that the kernel
does restore the previous added multicast addresses. Therefore,
there is no issues.

I found that this is due to mainly this commit below which
doesn't remove idev when the addresses are deleted.

commit 6363097cc4d182f93788131b5d8f72aa91d950a0
Author: Herbert Xu <herbert@...dor.apana.org.au>
Date:   Thu Jun 7 18:35:38 2007 -0700

    [IPV4]: Do not remove idev when addresses are cleared

    Now that we create idev before addresses are added, it no longer makes
    sense to remove them when addresses are all deleted.

    Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>
    Signed-off-by: David S. Miller <davem@...emloft.net>

Although the new behavior seems nice and save some user space
work, I think it was unintentional and likely to be a bug.

What you guys think?

thanks,
fbl
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html