[PATCH net] ipv4: fix ifa_flags reuse problem in using ifconfig tool

[PATCH net] ipv4: fix ifa_flags reuse problem in using ifconfig tool

[Su Yanjun]

When NetworkManager has already set ipv4 address then uses
ifconfig set another ipv4 address. It will use previous ifa_flags
that will cause device route not be inserted.

As NetworkManager has already support IFA_F_NOPREFIXROUTE flag [1],
but ifconfig will reuse the ifa_flags. It's weird especially
some old scripts or program [2]  still  use ifconfig.

[1] https://gitlab.freedesktop.org/NetworkManager/NetworkManager/
commit/fec80e7473ad16979af75ed299d68103e7aa3fe9

[2] LTP or TAHI

Signed-off-by: Su Yanjun <suyj.fnst@cn.fujitsu.com>
---
 net/ipv4/devinet.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index a4b5bd4..56ca339 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -1159,6 +1159,7 @@ int devinet_ioctl(struct net *net, unsigned int cmd, struct ifreq *ifr)
 			inet_del_ifa(in_dev, ifap, 0);
 			ifa->ifa_broadcast = 0;
 			ifa->ifa_scope = 0;
+			ifa->ifa_flags = 0;
 		}
 
 		ifa->ifa_address = ifa->ifa_local = sin->sin_addr.s_addr;
-- 
2.7.4

Re: [PATCH net] ipv4: fix ifa_flags reuse problem in using ifconfig tool

[David Miller]

From: Su Yanjun <suyj.fnst@cn.fujitsu.com>
Date: Wed, 4 Sep 2019 15:37:47 +0800

> When NetworkManager has already set ipv4 address then uses
> ifconfig set another ipv4 address. It will use previous ifa_flags
> that will cause device route not be inserted.
> 
> As NetworkManager has already support IFA_F_NOPREFIXROUTE flag [1],
> but ifconfig will reuse the ifa_flags. It's weird especially
> some old scripts or program [2]  still  use ifconfig.
> 
> [1] https://gitlab.freedesktop.org/NetworkManager/NetworkManager/
> commit/fec80e7473ad16979af75ed299d68103e7aa3fe9
> 
> [2] LTP or TAHI
> 
> Signed-off-by: Su Yanjun <suyj.fnst@cn.fujitsu.com>

I don't know about this.

This will lose things like IFA_F_SECONDARY as well.

Sorry, I am not convinced that this change is correct nor safe.