netdev - Re: [PATCH] net: Fix behavior of unreachable, blackhole and prohibit routes

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-prev] [day] [month] [year] [list]

Date:	Thu, 03 Sep 2015 11:05:14 +0200
From:	Nikola Forró <nforro@...hat.com>
To:	Alexander Duyck <alexander.duyck@...il.com>, netdev@...r.kernel.org
Cc:	David Miller <davem@...emloft.net>,
	Stephen Hemminger <stephen@...workplumber.org>
Subject: Re: [PATCH] net: Fix behavior of unreachable, blackhole and
 prohibit routes

Hello Alexander,
thank you for your comments.

On 09/01/2015 10:53 AM, Alexander Duyck wrote:

> Generally updating kernel code to match user-space documentation
> isn't 
> always the best way to go.  The question I would have is if there are
> any other user-space applications out there that might be expecting
> this 
> behaviour now?
> 
Well, any application which uses connect or sendto syscalls is getting
wrong error codes. If not wrong, than at least different for ipv4 and
ipv6. I think errors in fib_props are defined for a reason.

But I think bigger issue are incorrect ICMP messages being returned to
sender, e.g. packet going to blackhole route is not silently discarded,
instead it generates ICMP net unreachable message. I think that kind of
breaks the purpose of blackhole route.

> Also your changes don't seem to match up with what you have
> described. 
> You are returning the error code from fib_table_lookup, but 
> fib_table_lookup can return -EAGAIN if there is no matching entry
> found. 
>   I don't see you describing how you would deal with that case.  You 
> might try testing your code after deleting the default route to see
> what 
> behaviour it is you get.
> 
You are right, I need to handle -EAGAIN and return -ENETUNREACH
instead.

> This bit appears to overlook the fact that fib_rules_lookup could
> also 
> be the function used to return the error via a call to fib_lookup. 
>  In 
> which case that also throws -ESRCH into the mix for return error
> codes.
> 
I don't think it does. In __fib_lookup -ESRCH returned from
fib_rules_lookup is being replaced by -ENETUNREACH.


I will submit corrected patch.

Kind regards,
Nikola
--
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