From: Mira Ressel <aranea@aixah.de>
To: David Miller <davem@davemloft.net>
Cc: kuba@kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] veth: Initialize dev->perm_addr
Date: Wed, 26 Aug 2020 16:29:01 +0000 [thread overview]
Message-ID: <20200826162901.4js4u5u2whusp4l4@vega> (raw)
In-Reply-To: <20200826.082857.584544823490249841.davem@davemloft.net>
On Wed, Aug 26, 2020 at 08:28:57AM -0700, David Miller wrote:
> From: Mira Ressel <aranea@aixah.de>
> Date: Wed, 26 Aug 2020 15:20:00 +0000
>
> > I'm setting the peer->perm_addr, which would otherwise be zero, to its
> > dev_addr, which has been either generated randomly by the kernel or
> > provided by userland in a netlink attribute.
>
> Which by definition makes it not necessarily a "permanent address" and
> therefore is subject to being different across boots, which is exactly
> what you don't want to happen for automatic address generation.
That's true, but since veth devices aren't backed by any hardware, I
unfortunately don't have a good source for a permanent address. The only
inherently permanent thing about them is their name.
People who use the default eui64-based address generation don't get
persistent link-local addresses for their veth devices out of the box
either -- the EUI64 is derived from the device's dev_addr, which is
randomized by default.
If that presents a problem for anyone, they can configure their userland
to set the dev_addr to a static value, which handily fixes this problem
for both address generation algorithms.
I'm admittedly glancing over one problem here -- I'm only setting the
perm_addr during device creation, whereas userland can change the
dev_addr at any time. I'm not sure if it'd make sense here to update the
perm_addr if the dev_addr is changed later on?
--
Regards,
Mira
next prev parent reply other threads:[~2020-08-26 16:29 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-24 14:38 [PATCH 1/2] veth: Initialize dev->perm_addr Mira Ressel
2020-08-24 14:47 ` [PATCH 2/2] vlan: " Mira Ressel
2020-08-24 17:25 ` [PATCH 1/2] veth: " David Miller
2020-08-26 15:20 ` Mira Ressel
2020-08-26 15:28 ` David Miller
2020-08-26 16:29 ` Mira Ressel [this message]
2020-08-26 16:33 ` David Miller
2020-08-27 1:04 ` Mira Ressel
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