From: Xie He <xie.he.0141@gmail.com>
To: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Cc: Cong Wang <xiyou.wangcong@gmail.com>,
Network Development <netdev@vger.kernel.org>,
syzbot <syzbot+4a2c52677a8a1aa283cb@syzkaller.appspotmail.com>,
William Tu <u9012063@gmail.com>
Subject: Re: [Patch net] ip_gre: set dev->hard_header_len properly
Date: Thu, 8 Oct 2020 14:54:34 -0700 [thread overview]
Message-ID: <CAJht_ENxoAyUOoiHSbFXEZ6Jf2xqfOmYfQ6Sh-hfmTUk-kTrfQ@mail.gmail.com> (raw)
In-Reply-To: <CA+FuTSfhDgn-Qej4HOY-kYWSy8pUsnafMk=ozwtYGfS4W2DNuA@mail.gmail.com>
On Thu, Oct 8, 2020 at 2:48 PM Willem de Bruijn
<willemdebruijn.kernel@gmail.com> wrote:
>
> > I see the ipgre_xmit function would pull the header our header_ops
> > creates, and then call __gre_xmit. __gre_xmit will call
> > gre_build_header to complete the GRE header. gre_build_header expects
> > to find the base GRE header after pushing tunnel->tun_hlen. However,
> > if tunnel->encap_hlen is not 0, it couldn't find the base GRE header
> > there. Is there a problem?
> >
> > Where exactly should we put the tunnel->encap_hlen header? Before the
> > GRE header or after?
>
> The L4 tunnel infra uses the two callbacks encap_hlen (e.g.,
> fou_encap_hlen) and build_header (fou_build_header) in struct
> ip_tunnel_encap_ops to first allocate more space and later call back
> into the specific implementation to fill that data. build_header is
> called from __gre6_xmit -> ip6_tnl_xmit (or its ipv4 equivalent).
> This happens after gre has pushed its header, so the headers
> will come before that.
OK. If the t->encap_hlen header needs to be placed before the GRE
header, then I think the ipgre_header function should leave some space
before the GRE header to place the t->encap_hlen header, rather than
leaving space after the GRE header.
next prev parent reply other threads:[~2020-10-08 21:54 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-08 1:21 [Patch net] ip_gre: set dev->hard_header_len properly Cong Wang
2020-10-08 11:48 ` Willem de Bruijn
2020-10-08 17:33 ` Cong Wang
2020-10-08 19:04 ` Willem de Bruijn
2020-10-08 19:16 ` Xie He
2020-10-08 19:19 ` Willem de Bruijn
2020-10-08 20:10 ` Xie He
2020-10-08 20:31 ` Willem de Bruijn
2020-10-08 21:35 ` Xie He
2020-10-08 21:47 ` Willem de Bruijn
2020-10-08 21:54 ` Xie He [this message]
2020-10-08 23:40 ` Xie He
2020-10-09 17:43 ` Cong Wang
2020-10-09 19:41 ` Xie He
2020-10-09 19:51 ` Xie He
2020-10-09 20:38 ` Cong Wang
2020-10-10 1:07 ` Cong Wang
2020-10-10 3:10 ` Xie He
2020-10-10 18:58 ` Cong Wang
2020-10-10 21:49 ` Xie He
2020-10-11 3:55 ` Xie He
2020-10-11 14:35 ` Xie He
2020-10-08 19:18 ` Willem de Bruijn
2020-10-08 19:50 ` Cong Wang
2020-10-08 20:19 ` Willem de Bruijn
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CAJht_ENxoAyUOoiHSbFXEZ6Jf2xqfOmYfQ6Sh-hfmTUk-kTrfQ@mail.gmail.com \
--to=xie.he.0141@gmail.com \
--cc=netdev@vger.kernel.org \
--cc=syzbot+4a2c52677a8a1aa283cb@syzkaller.appspotmail.com \
--cc=u9012063@gmail.com \
--cc=willemdebruijn.kernel@gmail.com \
--cc=xiyou.wangcong@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).