Subject: Re: [PATCHv3 net-next 2/3] bonding: Add ESN support to IPSec HW offload

From: Sabrina Dubroca <[email-masked]>
Date: Wed, 21 Aug 2024 15:39:48 +0200

2024-08-21, 21:26:00 +0800, Hangbin Liu wrote:
> On Wed, Aug 21, 2024 at 02:30:41PM +0200, Steffen Klassert wrote:
> > > > +/**
> > > > + * bond_advance_esn_state - ESN support for IPSec HW offload
> > > > + * @xs: pointer to transformer state struct
> > > > + **/
> > > > +static void bond_advance_esn_state(struct xfrm_state *xs)
> > > > +{
> > > > +	struct net_device *real_dev;
> > > > +
> > > > +	rcu_read_lock();
> > > > +	real_dev = bond_ipsec_dev(xs);
> > > > +	if (!real_dev)
> > > > +		goto out;
> > > > +
> > > > +	if (!real_dev->xfrmdev_ops ||
> > > > +	    !real_dev->xfrmdev_ops->xdo_dev_state_advance_esn) {
> > > > +		pr_warn("%s: %s doesn't support xdo_dev_state_advance_esn\n", __func__, real_dev->name);
> > > 
> > > xdo_dev_state_advance_esn is called on the receive path for every
> > > packet when ESN is enabled (xfrm_input -> xfrm_replay_advance ->
> > > xfrm_replay_advance_esn -> xfrm_dev_state_advance_esn), this needs to
> > > be ratelimited.
> > 
> > How does xfrm_state offload work on bonding?
> > Does every slave have its own negotiated SA?
> 
> Yes and no. Bonding only supports xfrm offload with active-backup mode. So only
> current active slave keep the SA. When active slave changes, the sa on
> previous slave is deleted and re-added on new active slave.

It's the same SA, there's no DELSA+NEWSA when we change the active
slave (but we call xdo_dev_state_delete/xdo_dev_state_add to inform
the driver/HW), and only a single NEWSA to install the offloaded SA on
the bond device (which calls the active slave's xdo_dev_state_add).

-- 
Sabrina