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From: Eyal Birger <eyal.birger@gmail.com>
To: Corey Minyard <minyard@acm.org>
Cc: Steffen Klassert <steffen.klassert@secunet.com>,
	Herbert Xu <herbert@gondor.apana.org.au>,
	"David S. Miller" <davem@davemloft.net>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	Linux Kernel Network Developers <netdev@vger.kernel.org>
Subject: Re: IPSec questions and comments
Date: Sat, 24 Jul 2021 05:40:50 +0300	[thread overview]
Message-ID: <CAHsH6Gu12oTqeE_TV6suU8Qoa9tET-XCUDc_x+TkFrZuWMrhJQ@mail.gmail.com> (raw)
In-Reply-To: <20210724010117.GA633665@minyard.net>

Ho Corey,

On Sat, Jul 24, 2021 at 4:02 AM Corey Minyard <minyard@acm.org> wrote:
> 1) In struct xfrm_dst, what is the difference between the route and path
> fields?  From what I can tell, in the first element of a bundle they
> will both point the route the packet will take after it has been
> transformed.  In the other elements of a bundle, route is the same as in
> the first element and path will be NULL.  Is this really the intent?
> Can path just be eliminated?

For non-transport modes - such as tunnel - 'route' and 'path' won't be the
same in the first element (xdst0): 'route' will be the original dst and
'path' will be the route the transformed packet will take. the dst is
overridden in the xfrm_dst_lookup() call within xfrm_bundle_create(), after
xdst->route had been set.

AFAICT, the intent for the 'path' member is described in commit
0f6c480f23f4 ("xfrm: Move dst->path into struct xfrm_dst") - essentially
'path' contains the reference to the underlay route from the topmost bundle
member avoiding a walk through the child chain when needed.

Hope this helps.
Eyal.

  reply	other threads:[~2021-07-24  2:41 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-24  1:01 IPSec questions and comments Corey Minyard
2021-07-24  2:40 ` Eyal Birger [this message]
     [not found] ` <91bce7da-163d-dee3-5309-ebcf27de1abb@gmail.com>
2021-07-24  6:15   ` question about configuring multiple interfaces on a host within the same ipv6 sub-net hui wang
2021-07-25  2:32     ` hui wang
2021-07-26  8:13 ` IPSec questions and comments Steffen Klassert

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