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Message-ID: <540D9E3A.4010208@6wind.com> Date: Mon, 08 Sep 2014 14:16:58 +0200 From: Nicolas Dichtel <nicolas.dichtel@...nd.com> To: Eric Dumazet <eric.dumazet@...il.com> CC: David Miller <davem@...emloft.net>, therbert@...gle.com, alexander.h.duyck@...el.com, netdev@...r.kernel.org Subject: Re: [PATCH net] ipv6: refresh rt6i_genid in ip6_pol_route() Le 08/09/2014 12:28, Eric Dumazet a écrit : > On Mon, 2014-09-08 at 10:11 +0200, Nicolas Dichtel wrote: >> Le 08/09/2014 07:07, Eric Dumazet a écrit : >>> On Sun, 2014-09-07 at 21:59 -0700, David Miller wrote: >>>> From: Eric Dumazet <eric.dumazet@...il.com> >>>> Date: Sun, 07 Sep 2014 21:43:54 -0700 >>>> >>>>> On Sun, 2014-09-07 at 21:27 -0700, David Miller wrote: >>>>>> From: Eric Dumazet <eric.dumazet@...il.com> >>>>>> Date: Sun, 07 Sep 2014 21:18:25 -0700 >>>>>> >>>>>>> On Sun, 2014-09-07 at 15:54 -0700, David Miller wrote: >>>>>>> >>>>>>>> This might be broken. >>>>>>>> >>>>>>>> We are dealing here with persistent entries in the ipv6 routine trie. >>>>>>>> >>>>>>>> If you just bump the genid on the next person to look it up, other >>>>>>>> sockets and cached entities might not have validated the route yet, >>>>>>>> and now will falsely see the route as valid. We have to ensure that >>>>>>>> they too drop this route and perform a relookup. >>>>>>> >>>>>>> I am confused, I thought it was the role of the cookie. >>>>>>> >>>>>>> (Ie socket has to store its own cookie to be able to validate a route) >>>>>>> >>>>>>> Before 6f3118b571b8 patch, how was this done anyway ? >>>>>>> >>>>>>> If persistent routes cannot refresh the genid, then they are useless ? >>>>>> >>>>>> I just speak about the genid aspect. >>>>>> >>>>>> I understand that cookie (via node->fn_sernum) invalidates the path >>>>>> in the fib_trie, but the genid protects against other circumstances >>>>>> (matching IPSEC rule, f.e.) >>>>>> >>>>>> You have to make sure all other sockets did a full route lookup >>>>>> (including IPSEC) before you can safely adjust the genid. >>>>>> >>>>>> I could be wrong, recheck my analysis please :-) >>>>> >>>>> So this whole genid protection can not work, unless we make sure a >>>>> socket cannot share a route with another socket. >>>>> >>>>> This means we have to clone all routes. >>>> >>>> I'm willing to revert the change in question if you think that's the >>>> sanest way forward. >>>> >>>> The bug fix for more obscure use cases (IPSEC) if pointless if it >>>> breaks more common things (TCP input route caching). >>> >>> Lets wait for Nicolas and/or Hannes input, they might have some ideas... >> >> The initial problem was in SCTP. Here is the thread after the v1 patch: >> http://patchwork.ozlabs.org/patch/182235/ >> >> Before the patch, SCTP stored the IPv6 route in its cache and if an IPsec >> rules was inserted after that operation, SCTP never invalidated the cached >> route to use a new xfrm route. > > This thread mentions output route. Yes, it was the target. > > The problem I currently have with IPv6 early demux is for input routes. It's clearly a regression. -- 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
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