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Message-ID: <CADsK2K_na0Ugwv2PPT_s4oHSAx2rtZvtYY58C4MQkjE6G5y4Ew@mail.gmail.com>
Date: Tue, 26 Nov 2024 13:54:20 -0800
From: Feng Wang <wangfe@...gle.com>
To: Leon Romanovsky <leon@...nel.org>
Cc: netdev@...r.kernel.org, steffen.klassert@...unet.com,
antony.antony@...unet.com, pabeni@...hat.com
Subject: Re: [PATCH v6] xfrm: add SA information to the offloaded packet when
if_id is set
Please see embedded answers below. Thanks.
On Sun, Nov 24, 2024 at 12:15 AM Leon Romanovsky <leon@...nel.org> wrote:
>
> On Thu, Nov 21, 2024 at 09:52:58PM +0000, Feng Wang wrote:
> > In packet offload mode, append Security Association (SA) information
> > to each packet, replicating the crypto offload implementation.
>
> Please write explicitly WHY "replicating ..." is right thing to do and
> why current code is not enough.
>
> The best thing will be to see how packet traversal in the netdev stack
> till it gets to the wire.
>
I explained why doing this change in the third paragraph based on
Steffen's suggestion, I can move it here.
> >
> > The XFRM_XMIT flag is set to enable packet to be returned immediately
> > from the validate_xmit_xfrm function, thus aligning with the existing
> > code path for packet offload mode.
>
> This chunk was dropped mysteriously. It doesn't exist in the current patch.
> What type of testing did you perform? Can you please add it to the
> commit message?
>
I didn't drop any code in the current patch, I created a test and the
patch will be upstreamed after this change is checked in.
The link is https://lore.kernel.org/all/20241104233315.3387982-1-wangfe@google.com/
Do I need to add the test details in this commit?
> According to the strongswan documentation https://docs.strongswan.org/docs/5.9/features/routeBasedVpn.html,
> "Traffic that’s routed to an XFRM interface, while no policies and SAs with matching interface ID exist,
> will be dropped by the kernel."
>
> It looks like the current code doesn't handle this case, does it?
>
The current code will drop the packet if the interface ID is not matched.
> >
> > This SA info helps HW offload match packets to their correct security
> > policies. The XFRM interface ID is included, which is used in setups
> > with multiple XFRM interfaces where source/destination addresses alone
> > can't pinpoint the right policy.
>
> Please add an examples of iproute2 commands on how it is achieved,
> together with tcprdump examples of before and after.
>
A test patch will be upstreamed. There is no need for tcpdump because
this change won't change packet content.
> >
> > Enable packet offload mode on netdevsim and add code to check the XFRM
> > interface ID.
>
> You still need to add checks in existing drivers to make sure that SAs
> with if_id won't be offloaded.
>
There is no existing driver supporting packet offload mode except netdevsim.
> IMHO, netdevsim implementation is not a replacement to support
> out-of-tree code, but a way to help testing features without need to
> have complex HW, but still for the code which is in-tree.
>
We discussed this before, and I followed your and Steffen's comment to
add netdevsim simulation code to satisfy the requirement.
> Thanks
>
> >
> > Signed-off-by: wangfe <wangfe@...gle.com>
> > ---
> > v6: https://lore.kernel.org/all/20241119220411.2961121-1-wangfe@google.com/
> > - Fix code style to follow reverse x-mas tree order declaration.
> > v5: https://lore.kernel.org/all/20241112192249.341515-1-wangfe@google.com/
> > - Add SA information only when XFRM interface ID is non-zero.
> > v4: https://lore.kernel.org/all/20241104233251.3387719-1-wangfe@google.com/
> > - Add offload flag check and only doing check when XFRM interface
> > ID is non-zero.
> > v3: https://lore.kernel.org/all/20240822200252.472298-1-wangfe@google.com/
> > - Add XFRM interface ID checking on netdevsim in the packet offload
> > mode.
> > v2:
> > - Add why HW offload requires the SA info to the commit message
> > v1: https://lore.kernel.org/all/20240812182317.1962756-1-wangfe@google.com/
> > ---
> > ---
> > drivers/net/netdevsim/ipsec.c | 32 ++++++++++++++++++++++++++++++-
> > drivers/net/netdevsim/netdevsim.h | 1 +
> > net/xfrm/xfrm_output.c | 22 +++++++++++++++++++++
> > 3 files changed, 54 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/netdevsim/ipsec.c b/drivers/net/netdevsim/ipsec.c
> > index 88187dd4eb2d..5677b2acf9c0 100644
> > --- a/drivers/net/netdevsim/ipsec.c
> > +++ b/drivers/net/netdevsim/ipsec.c
> > @@ -153,7 +153,8 @@ static int nsim_ipsec_add_sa(struct xfrm_state *xs,
> > return -EINVAL;
> > }
> >
> > - if (xs->xso.type != XFRM_DEV_OFFLOAD_CRYPTO) {
> > + if (xs->xso.type != XFRM_DEV_OFFLOAD_CRYPTO &&
> > + xs->xso.type != XFRM_DEV_OFFLOAD_PACKET) {
> > NL_SET_ERR_MSG_MOD(extack, "Unsupported ipsec offload type");
> > return -EINVAL;
> > }
> > @@ -169,6 +170,7 @@ static int nsim_ipsec_add_sa(struct xfrm_state *xs,
> > memset(&sa, 0, sizeof(sa));
> > sa.used = true;
> > sa.xs = xs;
> > + sa.if_id = xs->if_id;
> >
> > if (sa.xs->id.proto & IPPROTO_ESP)
> > sa.crypt = xs->ealg || xs->aead;
> > @@ -227,16 +229,31 @@ static bool nsim_ipsec_offload_ok(struct sk_buff *skb, struct xfrm_state *xs)
> > return true;
> > }
> >
> > +static int nsim_ipsec_add_policy(struct xfrm_policy *policy,
> > + struct netlink_ext_ack *extack)
> > +{
> > + return 0;
> > +}
> > +
> > +static void nsim_ipsec_del_policy(struct xfrm_policy *policy)
> > +{
> > +}
> > +
> > static const struct xfrmdev_ops nsim_xfrmdev_ops = {
> > .xdo_dev_state_add = nsim_ipsec_add_sa,
> > .xdo_dev_state_delete = nsim_ipsec_del_sa,
> > .xdo_dev_offload_ok = nsim_ipsec_offload_ok,
> > +
> > + .xdo_dev_policy_add = nsim_ipsec_add_policy,
> > + .xdo_dev_policy_delete = nsim_ipsec_del_policy,
> > +
> > };
> >
> > bool nsim_ipsec_tx(struct netdevsim *ns, struct sk_buff *skb)
> > {
> > struct sec_path *sp = skb_sec_path(skb);
> > struct nsim_ipsec *ipsec = &ns->ipsec;
> > + struct xfrm_offload *xo;
> > struct xfrm_state *xs;
> > struct nsim_sa *tsa;
> > u32 sa_idx;
> > @@ -275,6 +292,19 @@ bool nsim_ipsec_tx(struct netdevsim *ns, struct sk_buff *skb)
> > return false;
> > }
> >
> > + if (xs->if_id) {
> > + if (xs->if_id != tsa->if_id) {
> > + netdev_err(ns->netdev, "unmatched if_id %d %d\n",
> > + xs->if_id, tsa->if_id);
> > + return false;
> > + }
> > + xo = xfrm_offload(skb);
> > + if (!xo || !(xo->flags & XFRM_XMIT)) {
> > + netdev_err(ns->netdev, "offload flag missing or wrong\n");
> > + return false;
> > + }
> > + }
> > +
> > ipsec->tx++;
> >
> > return true;
> > diff --git a/drivers/net/netdevsim/netdevsim.h b/drivers/net/netdevsim/netdevsim.h
> > index bf02efa10956..4941b6e46d0a 100644
> > --- a/drivers/net/netdevsim/netdevsim.h
> > +++ b/drivers/net/netdevsim/netdevsim.h
> > @@ -41,6 +41,7 @@ struct nsim_sa {
> > __be32 ipaddr[4];
> > u32 key[4];
> > u32 salt;
> > + u32 if_id;
> > bool used;
> > bool crypt;
> > bool rx;
> > diff --git a/net/xfrm/xfrm_output.c b/net/xfrm/xfrm_output.c
> > index e5722c95b8bb..3e9a1b17f37e 100644
> > --- a/net/xfrm/xfrm_output.c
> > +++ b/net/xfrm/xfrm_output.c
> > @@ -704,6 +704,8 @@ int xfrm_output(struct sock *sk, struct sk_buff *skb)
> > {
> > struct net *net = dev_net(skb_dst(skb)->dev);
> > struct xfrm_state *x = skb_dst(skb)->xfrm;
> > + struct xfrm_offload *xo;
> > + struct sec_path *sp;
> > int family;
> > int err;
> >
> > @@ -728,7 +730,27 @@ int xfrm_output(struct sock *sk, struct sk_buff *skb)
> > kfree_skb(skb);
> > return -EHOSTUNREACH;
> > }
> > + if (x->if_id) {
> > + 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);
> >
> > + xo = xfrm_offload(skb);
> > + if (!xo) {
> > + secpath_reset(skb);
> > + XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
> > + kfree_skb(skb);
> > + return -EINVAL;
> > + }
> > + xo->flags |= XFRM_XMIT;
> > + }
> > return xfrm_output_resume(sk, skb, 0);
> > }
> >
> > --
> > 2.47.0.371.ga323438b13-goog
> >
> >
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