netdev - Re: [PATCH] RFC: net: ipconfig: temporarily bring interface down when changing MTU.

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] [thread-next>] [day] [month] [year] [list]

Message-ID: <aa341e85-6a3f-4d4b-a2a7-b19bf0c9ba2f@kernel.org>
Date: Sat, 16 Dec 2023 11:12:46 -0700
From: David Ahern <dsahern@...nel.org>
To: Stephen Hemminger <stephen@...workplumber.org>,
 Graeme Smecher <gsmecher@...eespeedlogic.com>
Cc: "David S. Miller" <davem@...emloft.net>,
 Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
 Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org,
 claudiu.beznea@...on.dev, nicolas.ferre@...rochip.com, mdf@...nel.org
Subject: Re: [PATCH] RFC: net: ipconfig: temporarily bring interface down when
 changing MTU.

On 12/15/23 7:30 PM, Stephen Hemminger wrote:
>> diff --git a/net/ipv4/ipconfig.c b/net/ipv4/ipconfig.c
>> index c56b6fe6f0d7..69c2a41393a0 100644
>> --- a/net/ipv4/ipconfig.c
>> +++ b/net/ipv4/ipconfig.c
>> @@ -396,9 +396,21 @@ static int __init ic_setup_if(void)
>>  	 */
>>  	if (ic_dev_mtu != 0) {
>>  		rtnl_lock();
>> -		if ((err = dev_set_mtu(ic_dev->dev, ic_dev_mtu)) < 0)
>> -			pr_err("IP-Config: Unable to set interface mtu to %d (%d)\n",
>> -			       ic_dev_mtu, err);
>> +		/* Some Ethernet adapters only allow MTU to change when down. */
> Check if interface was already down first.

it is; see ic_open_devs. ic_close_devs will bring down all interfaces
not configured by ipconfig.