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Message-ID: <20241114102706.GB499069@unreal>
Date: Thu, 14 Nov 2024 12:27:06 +0200
From: Leon Romanovsky <leonro@...dia.com>
To: Feng Wang <wangfe@...gle.com>
CC: <netdev@...r.kernel.org>, <steffen.klassert@...unet.com>,
<antony.antony@...unet.com>
Subject: Re: [PATCH] xfrm: add SA information to the offloaded packet
On Tue, Nov 12, 2024 at 11:22:49AM -0800, Feng Wang wrote:
> From: wangfe <wangfe@...gle.com>
>
> In packet offload mode, append Security Association (SA) information
> to each packet, replicating the crypto offload implementation.
> 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 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.
>
> Enable packet offload mode on netdevsim and add code to check the XFRM
> interface ID.
>
> Signed-off-by: wangfe <wangfe@...gle.com>
> ---
> 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 | 21 ++++++++++++++++++++
> 3 files changed, 53 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/netdevsim/ipsec.c b/drivers/net/netdevsim/ipsec.c
> index f0d58092e7e9..afd2005bf7a8 100644
> --- a/drivers/net/netdevsim/ipsec.c
> +++ b/drivers/net/netdevsim/ipsec.c
> @@ -149,7 +149,8 @@ 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;
> }
> @@ -165,6 +166,7 @@ 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;
> @@ -224,10 +226,24 @@ 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)
> @@ -237,6 +253,7 @@ bool nsim_ipsec_tx(struct netdevsim *ns, struct sk_buff *skb)
> struct xfrm_state *xs;
> struct nsim_sa *tsa;
> u32 sa_idx;
> + struct xfrm_offload *xo;
>
> /* do we even need to check this packet? */
> if (!sp)
> @@ -272,6 +289,19 @@ bool nsim_ipsec_tx(struct netdevsim *ns, struct sk_buff *skb)
> return false;
> }
>
> + if (xs->if_id) {
If you are checking this, you will need to make sure that XFRM_XMIT is
set when if_id != 0. It is not how it is implemented now.
> + 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..a12588e7b060 100644
> --- a/net/xfrm/xfrm_output.c
> +++ b/net/xfrm/xfrm_output.c
> @@ -706,6 +706,8 @@ int xfrm_output(struct sock *sk, struct sk_buff *skb)
> struct xfrm_state *x = skb_dst(skb)->xfrm;
> int family;
> int err;
> + struct xfrm_offload *xo;
> + struct sec_path *sp;
>
> family = (x->xso.type != XFRM_DEV_OFFLOAD_PACKET) ? x->outer_mode.family
> : skb_dst(skb)->ops->family;
> @@ -728,6 +730,25 @@ int xfrm_output(struct sock *sk, struct sk_buff *skb)
> 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);
Not an expert and just looked how XFRM_XMIT is assigned in other places,
and simple skb_ext_add(skb, SKB_EXT_SEC_PATH) is used, why is it
different here?
The additional issue is that you are adding extension and flag to all
offloaded packets, which makes me wonder what to do with this check in
validate_xmit_xfrm():
136 /* The packet was sent to HW IPsec packet offload engine,
137 * but to wrong device. Drop the packet, so it won't skip
138 * XFRM stack.
139 */
140 if (x->xso.type == XFRM_DEV_OFFLOAD_PACKET && x->xso.dev != dev) {
141 kfree_skb(skb);
142 dev_core_stats_tx_dropped_inc(dev);
143 return NULL;
144 }
Also because you are adding it to all packets, you are adding extra
overhead for all users, even these who didn't ask this if_id thing.
And again, you should block creation of SAs with if_id != 0 for already
existing in-kernel IPsec implementations.
Thanks
> +
> + 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);
> }
> --
> 2.47.0.277.g8800431eea-goog
>
>
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