rp_filter backward compatibility

rp_filter backward compatibility

[Nicolas Dichtel]

I'm surprised by the commit 27fed4175acf81ddd91d9a4ee2fd298981f60295 (ip: fix 
logic of reverse path filter sysctl). This commit breaks backward compatibility.
I know that logic was wrong, but for years it was mandatory to set both 
all.rp_filter and <device>.rp_filter to enable it, ie setting only all.rp_filter 
had no consequences. Now, when all.rp_filter is enabled, RPF is enabled for all 
interfaces.
Help of Kconfig explains:

                                                                 "To turn
           rp_filter on use:

           echo 1 > /proc/sys/net/ipv4/conf/<device>/rp_filter
            *and*
           echo 1 > /proc/sys/net/ipv4/conf/all/rp_filter"

At least, one of this action should be done:
  - fixing help (Documentation/networking/ip-sysctl.txt is up to date)
  - reverting the patch (this will force to set all.rp_filter to 3 if some 
interfaces use loose mode and some others strict mode)

What is your opinion?

Regards,
Nicolas

Re: rp_filter backward compatibility

[David Miller]

From: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Date: Mon, 30 Aug 2010 17:25:22 +0200

> At least, one of this action should be done:
>  - fixing help (Documentation/networking/ip-sysctl.txt is up to date)

This is the only option.

Re: rp_filter backward compatibility

[Nicolas Dichtel]

[-- Attachment #1: Type: text/plain, Size: 312 bytes --]

Here is the (small) patch.

Regards,
Nicolas

David Miller wrote:
> From: Nicolas Dichtel <nicolas.dichtel@6wind.com>
> Date: Mon, 30 Aug 2010 17:25:22 +0200
> 
>> At least, one of this action should be done:
>>  - fixing help (Documentation/networking/ip-sysctl.txt is up to date)
> 
> This is the only option.

[-- Attachment #2: 0002-ipv4-minor-fix-about-RPF-in-help-of-Kconfig.patch --]
[-- Type: text/x-diff, Size: 760 bytes --]

>From a2ea92449b7bfe3952d4714e13df00f5b8595c86 Mon Sep 17 00:00:00 2001
From: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Date: Tue, 31 Aug 2010 17:47:42 +0200
Subject: [PATCH] ipv4: minor fix about RPF in help of Kconfig

Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
---
 net/ipv4/Kconfig |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/net/ipv4/Kconfig b/net/ipv4/Kconfig
index 7c3a7d1..571f895 100644
--- a/net/ipv4/Kconfig
+++ b/net/ipv4/Kconfig
@@ -46,7 +46,7 @@ config IP_ADVANCED_ROUTER
 	  rp_filter on use:
 
 	  echo 1 > /proc/sys/net/ipv4/conf/<device>/rp_filter
-	   and
+	   or
 	  echo 1 > /proc/sys/net/ipv4/conf/all/rp_filter
 
 	  Note that some distributions enable it in startup scripts.
-- 
1.5.6.5

Re: rp_filter backward compatibility

[David Miller]

From: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Date: Tue, 31 Aug 2010 17:50:43 +0200

> Here is the (small) patch.

Applied.