linux-kernel - Re: [PATCH] net: ipv6: don't generate link-local address in any addr_gen

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Message-ID: <20210705054802.31052-1-rocco.yue@mediatek.com>
Date:   Mon, 5 Jul 2021 13:48:02 +0800
From:   Rocco Yue <rocco.yue@...iatek.com>
To:     David Ahern <dsahern@...il.com>
CC:     "David S . Miller" <davem@...emloft.net>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        David Ahern <dsahern@...nel.org>,
        Jakub Kicinski <kuba@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>, <wsd_upstream@...iatek.com>,
        <rocco.yue@...il.com>, <chao.song@...iatek.com>,
        <kuohong.wang@...iatek.com>, <zhuoliang.zhang@...iatek.com>,
        Rocco Yue <rocco.yue@...iatek.com>
Subject: Re: [PATCH] net: ipv6: don't generate link-local address in any addr_gen_mode

On Thu, 2021-07-01 at 16:51 +0800, Rocco Yue wrote:
> On Wed, 2021-06-30 at 22:41 -0600, David Ahern wrote:
>> On 6/30/21 9:39 PM, Rocco Yue wrote:
>>> 
>>> Hi David,
>>> 
>>> Thanks for your review.
>>> 
>>> This patch is different with IN6_ADDR_GEN_MODE_NONE.
>>> 
>>> When the addr_gen_mode == IN6_ADDR_GEN_MODE_NONE, the Linux kernel
>>> doesn't automatically generate the ipv6 link-local address.
>>> 
>> 
>> ...
>> 
>>> 
>>> After this patch, when the "disable_gen_linklocal_addr" value of a device
>>> is 1, no matter in which addr_gen_mode, the Linux kernel will not automatically
>>> generate an ipv6 link-local for this device.
>>> 
>> 
>> those 2 sentences are saying the same thing to me.
>> 
>> for your use case, why is setting addr_gen_mode == 1 for the device not
>> sufficient?
>> 
> 
> For mobile operators that don't need to support RFC7217, setting
> addr_gen_mode == 1 is sufficient;
> 
> But for some other mobile operators that need to support RFC7217, such as AT&T,
> the mobile device's addr_gen_mode will be switched to the
> IN6_ADDR_GEN_MODE_STABLE_PRIVACY, instead of using IN6_ADDR_GEN_MODE_NONE.
> The purpose is: in the IN6_ADDR_GEN_MODE_STABLE_PRIVACY mode, kernel can
> gererate a stable privacy global ipv6 address after receiveing RA, and
> network processes can use this global address to communicate with the
> outside network.
> 
> Of course, mobile operators that need to support RFC7217 should also meet
> the requirement of 3GPP TS 29.061, that is, MT should use IID assigned by
> the GGSN to build its ipv6 link-local address and use this address to send RS.
> We don't want the kernel to automatically generate an ipv6 link-local address
> when addr_gen_mode == 2. Otherwise, using the stable privacy ipv6 link-local
> address automatically generated by the kernel to send RS message, GGSN will
> not be able to respond to the RS and reply a RA message.
> 
> Therefore, after this patch, kernel will not generate ipv6 link-local address
> for the corresponding device when addr_gen_mode == 1 or addr_gen_mode == 2.
> 
> Thanks,
> Rocco
> 

Hi David,

Gentle ping for this patch.

Thanks,
Rocco