netdev - RE: [EXT] Re: Setting security path with IPsec packet offload mode

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Message-ID: 
 <DM5PR1801MB1883FCE87F49E7A2651B2A70E323A@DM5PR1801MB1883.namprd18.prod.outlook.com>
Date: Fri, 23 Jun 2023 06:48:21 +0000
From: Bharat Bhushan <bbhushan2@...vell.com>
To: Leon Romanovsky <leon@...nel.org>
CC: Steffen Klassert <steffen.klassert@...unet.com>,
        "herbert@...dor.apana.org.au" <herbert@...dor.apana.org.au>,
        "David S.
 Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>, Jakub
 Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: RE: [EXT] Re: Setting security path with IPsec packet offload mode

Hi Leon,

> -----Original Message-----
> From: Leon Romanovsky <leon@...nel.org>
> Sent: Thursday, June 22, 2023 2:05 PM
> To: Bharat Bhushan <bbhushan2@...vell.com>
> Cc: Steffen Klassert <steffen.klassert@...unet.com>;
> herbert@...dor.apana.org.au; David S. Miller <davem@...emloft.net>; Eric
> Dumazet <edumazet@...gle.com>; Jakub Kicinski <kuba@...nel.org>; Paolo
> Abeni <pabeni@...hat.com>; netdev@...r.kernel.org
> Subject: [EXT] Re: Setting security path with IPsec packet offload mode
> 
> External Email
> 
> ----------------------------------------------------------------------
> On Thu, Jun 22, 2023 at 06:58:06AM +0000, Bharat Bhushan wrote:
> > Hi All,
> >
> > Have a query related to security patch (secpath_set()) with packet offload
> mode on egress side. Working to enable ipsec packet offload while Crypto
> offload is working.
> > For packet offload xfrm_offload(*skb) returns false in driver. While looking in
> xfrm framework, cannot find where security patch (secpath_set()) is set with
> packet offload mode on egress side.
> 
> The idea of packet offload is to take plain text packets and perform all needed
> magic in HW without need from driver and stack to make anything.

So driver does not know whether it normal packet and will be transmitted normally or this will undergo inline ipsec in hardware.

In our case packet transmit requires a different code flow in driver, to pass some extra details in transmit descriptor like state and policy pointers. So is there some way driver can find same and extra state and policy details from skb? 

Thanks
-Bharat

> 
> We don't set secpath in TX path as such packets exit from XFRM as "plain" ones
> toward HW.
> It is different in RX, we set there, as XFRM core still needs to perform some code
> on the arrived packets, before forwarding them to stack.
> 
> Thanks
> 
> >
> > For sure I might be missing something here and looking for help to understand
> same. Meantime just tried below hack:
> >
> > diff --git a/net/xfrm/xfrm_output.c b/net/xfrm/xfrm_output.c index
> > ff114d68cc43..8499c0e74a5a 100644
> > --- a/net/xfrm/xfrm_output.c
> > +++ b/net/xfrm/xfrm_output.c
> > @@ -718,12 +718,24 @@ int xfrm_output(struct sock *sk, struct sk_buff *skb)
> >         }
> >
> >         if (x->xso.type == XFRM_DEV_OFFLOAD_PACKET) {
> > +               struct sec_path *sp;
> >                 if (!xfrm_dev_offload_ok(skb, x)) {
> >                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
> >                         kfree_skb(skb);
> >                         return -EHOSTUNREACH;
> >                 }
> >
> > +               sp = secpath_set(skb);
> > +               if (!sp) {
> > +                       XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
> > +                       kfree_skb(skb);
> > +                       return -ENOMEM;
> > +               }
> > +
> > +               sp->olen++;
> > +               sp->xvec[sp->len++] = x;
> > +               xfrm_state_hold(x);
> > +
> >                 return xfrm_output_resume(sk, skb, 0);
> >         }
> >
> >
> > Thanks in advance,
> > -Bharat
> >