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Date: Wed, 27 Mar 2013 19:55:14 +0900
From: YOSHIFUJI Hideaki <yoshfuji@...ux-ipv6.org>
To: Balakumaran Kannan <kumaran.4353@...il.com>
CC: davem@...emloft.net, kuznet@....inr.ac.ru, jmorris@...ei.org,
kaber@...sh.net, netdev@...r.kernel.org,
Balakumaran.Kannan@...sony.com, maruthi.thotad@...sony.com,
YOSHIFUJI Hideaki <yoshfuji@...ux-ipv6.org>
Subject: Re: [PATCH] net : Fix broken IPv6 routing table after loopback down-up
Balakumaran Kannan wrote:
> IPv6 Routing table becomes broken once we do ifdown, ifup of the loopback(lo)
> interface. After down-up, routes of other interface's IPv6 addresses through
> 'lo' are lost.
>
> IPv6 addresses assigned to all interfaces are routed through 'lo' for internal
> communication. Once 'lo' is down, those routing entries are removed from
> routing table. But those removed entries are not being re-created properly when
> 'lo' is brought up. So IPv6 addresses of other interfaces becomes unreachable
> from the same machine. Also this breaks communication with other machines
> because of NDISC packet processing failure.
>
> This patch fixes this issue by reading all interface's IPv6 addresses and
> adding them to IPv6 routing table while bringing up 'lo'.
>
> Patch is prepared for Linux-3.9.rc4 kernel.
>
> Signed-off-by: Balakumaran Kannan <Balakumaran.Kannan@...sony.com>
> Signed-off-by: Maruthi Thotad <Maruthi.Thotad@...sm.sony.com>
> ---
> ==Testing==
> Before applying the patch:
> $ route -A inet6
> Kernel IPv6 routing table
> Destination Next Hop Flag Met Ref Use If
> 2000::20/128 :: U 256 0 0 eth0
> fe80::/64 :: U 256 0 0 eth0
> ::/0 :: !n -1 1 1 lo
> ::1/128 :: Un 0 1 0 lo
> 2000::20/128 :: Un 0 1 0 lo
> fe80::xxxx:xxxx:xxxx:xxxx/128 :: Un 0 1 0 lo
> ff00::/8 :: U 256 0 0 eth0
> ::/0 :: !n -1 1 1 lo
> $ sudo ifdown lo
> $ sudo ifup lo
> $ route -A inet6
> Kernel IPv6 routing table
> Destination Next Hop Flag Met Ref Use If
> 2000::20/128 :: U 256 0 0 eth0
> fe80::/64 :: U 256 0 0 eth0
> ::/0 :: !n -1 1 1 lo
> ::1/128 :: Un 0 1 0 lo
> ff00::/8 :: U 256 0 0 eth0
> ::/0 :: !n -1 1 1 lo
> $
>
> After applying the patch:
> $ route -A inet6
> Kernel IPv6 routing
> table
> Destination Next Hop Flag Met Ref Use If
> 2000::20/128 :: U 256 0 0 eth0
> fe80::/64 :: U 256 0 0 eth0
> ::/0 :: !n -1 1 1 lo
> ::1/128 :: Un 0 1 0 lo
> 2000::20/128 :: Un 0 1 0 lo
> fe80::xxxx:xxxx:xxxx:xxxx/128 :: Un 0 1 0 lo
> ff00::/8 :: U 256 0 0 eth0
> ::/0 :: !n -1 1 1 lo
> $ sudo ifdown lo
> $ sudo ifup lo
> $ route -A inet6
> Kernel IPv6 routing table
> Destination Next Hop Flag Met Ref Use If
> 2000::20/128 :: U 256 0 0 eth0
> fe80::/64 :: U 256 0 0 eth0
> ::/0 :: !n -1 1 1 lo
> ::1/128 :: Un 0 1 0 lo
> 2000::20/128 :: Un 0 1 0 lo
> fe80::xxxx:xxxx:xxxx:xxxx/128 :: Un 0 1 0 lo
> ff00::/8 :: U 256 0 0 eth0
> ::/0 :: !n -1 1 1 lo
> $
> ---
> --- linux-3.9-rc4/net/ipv6/addrconf.c.orig 2013-03-27 10:40:26.382569527 +0530
> +++ linux-3.9-rc4/net/ipv6/addrconf.c 2013-03-27 10:56:45.227354856 +0530
> @@ -2529,6 +2529,11 @@ static void sit_add_v4_addrs(struct inet
> static void init_loopback(struct net_device *dev)
> {
> struct inet6_dev *idev;
> + struct net_device *sp_dev;
> + struct inet6_ifaddr *sp_ifa;
> + struct list_head *sp_ifap;>
> static void addrconf_add_linklocal(struct inet6_dev *idev, const
> struct in6_addr *addr)
> --
> To unsubscribe from this list: send the line "unsubscribe netdev" in
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>
> + struct rt6_info *sp_rt;
> + int i = 1;
>
> /* ::1 */
>
> @@ -2540,6 +2545,27 @@ static void init_loopback(struct net_dev
> }
>
> add_addr(idev, &in6addr_loopback, 128, IFA_HOST);
> +
> + while ((sp_dev = dev_get_by_index(dev_net(dev), i++))) {
> +
I think this cannot work because we may have missing index.
Why no dev_get_by_name()?
> + if (!strcmp(sp_dev->name, dev->name)) {
> + dev_put(sp_dev);
> + continue;
> + }
> +
> + idev = ipv6_find_idev(sp_dev);
> + dev_put(sp_dev);
> + if (NULL == idev)
> + continue;
> +
> + list_for_each(sp_ifap, &idev->addr_list) {
> + sp_ifa = list_entry(sp_ifap, struct inet6_ifaddr,
> + if_list);
> + sp_rt = addrconf_dst_alloc(idev, &sp_ifa->addr, 0);
> + if (!IS_ERR(sp_rt))
> + ip6_ins_rt(sp_rt);
> + }
> + }
> }
lock?
--yoshfuji
--
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