netdev - Re: IPSec questions and comments

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]

Date:   Sat, 24 Jul 2021 05:40:50 +0300
From:   Eyal Birger <eyal.birger@...il.com>
To:     Corey Minyard <minyard@....org>
Cc:     Steffen Klassert <steffen.klassert@...unet.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Linux Kernel Network Developers <netdev@...r.kernel.org>
Subject: Re: IPSec questions and comments

Ho Corey,

On Sat, Jul 24, 2021 at 4:02 AM Corey Minyard <minyard@....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.