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Date: Thu, 25 Aug 2022 17:30:29 +0300
From: Nikolay Aleksandrov <razor@...ckwall.org>
To: Eyal Birger <eyal.birger@...il.com>, davem@...emloft.net,
edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
steffen.klassert@...unet.com, herbert@...dor.apana.org.au,
dsahern@...nel.org, contact@...elbtn.com, pablo@...filter.org,
nicolas.dichtel@...nd.com
Cc: netdev@...r.kernel.org, bpf@...r.kernel.org
Subject: Re: [PATCH ipsec-next,v2 3/3] xfrm: lwtunnel: add lwtunnel support
for xfrm interfaces in collect_md mode
On 25/08/2022 16:46, Eyal Birger wrote:
> Allow specifying the xfrm interface if_id and link as part of a route
> metadata using the lwtunnel infrastructure.
>
> This allows for example using a single xfrm interface in collect_md
> mode as the target of multiple routes each specifying a different if_id.
>
> With the appropriate changes to iproute2, considering an xfrm device
> ipsec1 in collect_md mode one can for example add a route specifying
> an if_id like so:
>
> ip route add <SUBNET> dev ipsec1 encap xfrm if_id 1
>
> In which case traffic routed to the device via this route would use
> if_id in the xfrm interface policy lookup.
>
> Or in the context of vrf, one can also specify the "link" property:
>
> ip route add <SUBNET> dev ipsec1 encap xfrm if_id 1 dev eth15
>
> Signed-off-by: Eyal Birger <eyal.birger@...il.com>
>
> ----
>
> v2:
> - move lwt_xfrm_info() helper to dst_metadata.h
> - add "link" property as suggested by Nicolas Dichtel
> ---
> include/net/dst_metadata.h | 11 ++++
> include/uapi/linux/lwtunnel.h | 10 ++++
> net/core/lwtunnel.c | 1 +
> net/xfrm/xfrm_interface.c | 100 ++++++++++++++++++++++++++++++++++
> 4 files changed, 122 insertions(+)
>
> diff --git a/include/net/dst_metadata.h b/include/net/dst_metadata.h
> index e4b059908cc7..57f75960fa28 100644
> --- a/include/net/dst_metadata.h
> +++ b/include/net/dst_metadata.h
> @@ -60,13 +60,24 @@ skb_tunnel_info(const struct sk_buff *skb)
> return NULL;
> }
>
> +static inline struct xfrm_md_info *lwt_xfrm_info(struct lwtunnel_state *lwt)
> +{
> + return (struct xfrm_md_info *)lwt->data;
> +}
> +
> static inline struct xfrm_md_info *skb_xfrm_md_info(const struct sk_buff *skb)
> {
> struct metadata_dst *md_dst = skb_metadata_dst(skb);
> + struct dst_entry *dst;
>
> if (md_dst && md_dst->type == METADATA_XFRM)
> return &md_dst->u.xfrm_info;
>
> + dst = skb_dst(skb);
> + if (dst && dst->lwtstate &&
> + dst->lwtstate->type == LWTUNNEL_ENCAP_XFRM)
> + return lwt_xfrm_info(dst->lwtstate);
> +
> return NULL;
> }
>
> diff --git a/include/uapi/linux/lwtunnel.h b/include/uapi/linux/lwtunnel.h
> index 2e206919125c..229655ef792f 100644
> --- a/include/uapi/linux/lwtunnel.h
> +++ b/include/uapi/linux/lwtunnel.h
> @@ -15,6 +15,7 @@ enum lwtunnel_encap_types {
> LWTUNNEL_ENCAP_SEG6_LOCAL,
> LWTUNNEL_ENCAP_RPL,
> LWTUNNEL_ENCAP_IOAM6,
> + LWTUNNEL_ENCAP_XFRM,
> __LWTUNNEL_ENCAP_MAX,
> };
>
> @@ -111,4 +112,13 @@ enum {
>
> #define LWT_BPF_MAX_HEADROOM 256
>
> +enum {
> + LWT_XFRM_UNSPEC,
> + LWT_XFRM_IF_ID,
> + LWT_XFRM_LINK,
> + __LWT_XFRM_MAX,
> +};
> +
> +#define LWT_XFRM_MAX (__LWT_XFRM_MAX - 1)
> +
> #endif /* _UAPI_LWTUNNEL_H_ */
> diff --git a/net/core/lwtunnel.c b/net/core/lwtunnel.c
> index 9ccd64e8a666..6fac2f0ef074 100644
> --- a/net/core/lwtunnel.c
> +++ b/net/core/lwtunnel.c
> @@ -50,6 +50,7 @@ static const char *lwtunnel_encap_str(enum lwtunnel_encap_types encap_type)
> return "IOAM6";
> case LWTUNNEL_ENCAP_IP6:
> case LWTUNNEL_ENCAP_IP:
> + case LWTUNNEL_ENCAP_XFRM:
> case LWTUNNEL_ENCAP_NONE:
> case __LWTUNNEL_ENCAP_MAX:
> /* should not have got here */
> diff --git a/net/xfrm/xfrm_interface.c b/net/xfrm/xfrm_interface.c
> index 389d8be12801..604de1ee3772 100644
> --- a/net/xfrm/xfrm_interface.c
> +++ b/net/xfrm/xfrm_interface.c
> @@ -60,6 +60,103 @@ struct xfrmi_net {
> struct xfrm_if __rcu *collect_md_xfrmi;
> };
>
> +static const struct nla_policy xfrm_lwt_policy[LWT_XFRM_MAX + 1] = {
> + [LWT_XFRM_UNSPEC] = { .type = NLA_REJECT },
IIRC this is automatically rejected (NL_VALIDATE_STRICT used by nla_parse_nested())
> + [LWT_XFRM_IF_ID] = { .type = NLA_U32 },
I think you can use NLA_POLICY_MIN() and simplify xfrmi_build_state() below
> + [LWT_XFRM_LINK] = { .type = NLA_U32 },
link is an int, so s32 and you can add validation via NLA_POLICY_MIN() so you
can remove the check for !info->link below
> +};
> +
> +static void xfrmi_destroy_state(struct lwtunnel_state *lwt)
> +{
> +}
> +
> +static int xfrmi_build_state(struct net *net, struct nlattr *nla,
> + unsigned int family, const void *cfg,
> + struct lwtunnel_state **ts,
> + struct netlink_ext_ack *extack)
> +{
> + struct nlattr *tb[LWT_XFRM_MAX + 1];
> + struct lwtunnel_state *new_state;
> + struct xfrm_md_info *info;
> + int ret;
> +
> + ret = nla_parse_nested(tb, LWT_XFRM_MAX, nla, xfrm_lwt_policy, extack);
> + if (ret < 0)
> + return ret;
> +
> + if (!tb[LWT_XFRM_IF_ID])
> + return -EINVAL;
> +
> + new_state = lwtunnel_state_alloc(sizeof(*info));
> + if (!new_state)
> + return -ENOMEM;
> +
> + new_state->type = LWTUNNEL_ENCAP_XFRM;
> +
> + info = lwt_xfrm_info(new_state);
> +
> + info->if_id = nla_get_u32(tb[LWT_XFRM_IF_ID]);
> + if (!info->if_id) {
> + ret = -EINVAL;
> + goto errout;
> + }
> +
> + if (tb[LWT_XFRM_LINK]) {
> + info->link = nla_get_u32(tb[LWT_XFRM_LINK]);
same, s32
> + if (!info->link) {
> + ret = -EINVAL;
> + goto errout;
> + }
> + }
> +
> + *ts = new_state;
> + return 0;
> +
> +errout:
> + xfrmi_destroy_state(new_state);
> + kfree(new_state);
> + return ret;
> +}
> +
> +static int xfrmi_fill_encap_info(struct sk_buff *skb,
> + struct lwtunnel_state *lwt)
> +{
> + struct xfrm_md_info *info = lwt_xfrm_info(lwt);
> +
> + if (nla_put_u32(skb, LWT_XFRM_IF_ID, info->if_id))
> + return -EMSGSIZE;
> +
> + if (info->link) {
> + if (nla_put_u32(skb, LWT_XFRM_LINK, info->link))
same and also minor nit: these can be combined
> + return -EMSGSIZE;
> + }
> +
> + return 0;
> +}
> +
> +static int xfrmi_encap_nlsize(struct lwtunnel_state *lwtstate)
> +{
> + return nla_total_size(4) + /* LWT_XFRM_IF_ID */
> + nla_total_size(4); /* LWT_XFRM_LINK */
nit: nla_total_size(sizeof(u32))
> +}
> +
> +static int xfrmi_encap_cmp(struct lwtunnel_state *a, struct lwtunnel_state *b)
> +{
> + struct xfrm_md_info *a_info = lwt_xfrm_info(a);
> + struct xfrm_md_info *b_info = lwt_xfrm_info(b);
> +
> + return memcmp(a_info, b_info, sizeof(*a_info));
> +}
> +
> +static const struct lwtunnel_encap_ops xfrmi_encap_ops = {
> + .build_state = xfrmi_build_state,
> + .destroy_state = xfrmi_destroy_state,
> + .fill_encap = xfrmi_fill_encap_info,
> + .get_encap_size = xfrmi_encap_nlsize,
> + .cmp_encap = xfrmi_encap_cmp,
> + .owner = THIS_MODULE,
> +};
> +
> #define for_each_xfrmi_rcu(start, xi) \
> for (xi = rcu_dereference(start); xi; xi = rcu_dereference(xi->next))
>
> @@ -1081,6 +1178,8 @@ static int __init xfrmi_init(void)
> if (err < 0)
> goto rtnl_link_failed;
>
> + lwtunnel_encap_add_ops(&xfrmi_encap_ops, LWTUNNEL_ENCAP_XFRM);
> +
> xfrm_if_register_cb(&xfrm_if_cb);
>
> return err;
> @@ -1099,6 +1198,7 @@ static int __init xfrmi_init(void)
> static void __exit xfrmi_fini(void)
> {
> xfrm_if_unregister_cb();
> + lwtunnel_encap_del_ops(&xfrmi_encap_ops, LWTUNNEL_ENCAP_XFRM);
> rtnl_link_unregister(&xfrmi_link_ops);
> xfrmi4_fini();
> xfrmi6_fini();
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