Date: Wed, 16 Jan 2013 23:40:16 +0530 (IST) From: P J P <ppandit@...hat.com> To: oss-security@...ts.openwall.com cc: kargig@...d.gr Subject: Re: Linux kernel handling of IPv6 temporary addresses Hello George, +-- On Wed, 16 Jan 2013, George Kargiotakis wrote --+ | what distro/kernel version are you trying ? I'm using latest ubuntu 12.10 with 3.5.7. | The messages I'm mentioning certainly appear upon testing with ubuntu 12.10 live CD for example. I'm using RHEL-6.3 with kernel-2.6.32. | Your new patch works "better", but still the main problem hasn't been | eliminated. And I explain myself. | | While flooding with RAs the following appears in the dmesg: | [ 117.721878] IPv6: ipv6_create_tempaddr: ipv6 temporary address upper limit reached | | which is what your patch is supposed to do. But acquired addresses | from flooding all seem to have the tentative flag on: | inet6 fd00:966f:7996:c731:9191:a3ce:99bc:897e/64 scope global temporary tentative dynamic Yes, I too observed similar output, not sure it's because of the patch though. I guess problem is somewhere else, I'm looking. | what I also find wrong here is that all temporary addresses (dynamic) | acquired have gotten the same last 64bits. I don't think this is OK per RFC | 4941 even if not explicitly defined there. Every temp. address created | should be different per prefix from the rest. | | use_tempaddr for the iface still has '2' as its value | # cat /proc/sys/net/ipv6/conf/eth0/use_tempaddr | 2 | | then after taking the interface down and up again even the new addresses acquired still have the tentative flag enabled: | | dmesg reports: | [ 322.195426] IPv6: ipv6_create_tempaddr: regeneration time exceeded - disabled temporary address support | | use_tempaddr for the iface now has '-1' as its value though | # cat /proc/sys/net/ipv6/conf/eth0/use_tempaddr | -1 | | And so there actually isn't any IPv6 connectivity from then on until a reboot. | Flooding triggers something that corrupts ipv6 functionality. I see, I'll try to look for these clues, will get back asap. Thanks so much. -- Prasad J Pandit / Red Hat Security Response Team DB7A 84C5 D3F9 7CD1 B5EB C939 D048 7860 3655 602B
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