netdev - Re: [PATCH v3 17/19] psp: provide decapsulation and receive helper for drivers

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Message-ID: <686aad51a4f7c_3ad0f329439@willemb.c.googlers.com.notmuch>
Date: Sun, 06 Jul 2025 13:07:29 -0400
From: Willem de Bruijn <willemdebruijn.kernel@...il.com>
To: Daniel Zahka <daniel.zahka@...il.com>, 
 Donald Hunter <donald.hunter@...il.com>, 
 Jakub Kicinski <kuba@...nel.org>, 
 "David S. Miller" <davem@...emloft.net>, 
 Eric Dumazet <edumazet@...gle.com>, 
 Paolo Abeni <pabeni@...hat.com>, 
 Simon Horman <horms@...nel.org>, 
 Jonathan Corbet <corbet@....net>, 
 Andrew Lunn <andrew+netdev@...n.ch>
Cc: Saeed Mahameed <saeedm@...dia.com>, 
 Leon Romanovsky <leon@...nel.org>, 
 Tariq Toukan <tariqt@...dia.com>, 
 Boris Pismenny <borisp@...dia.com>, 
 Kuniyuki Iwashima <kuniyu@...gle.com>, 
 Willem de Bruijn <willemb@...gle.com>, 
 David Ahern <dsahern@...nel.org>, 
 Neal Cardwell <ncardwell@...gle.com>, 
 Patrisious Haddad <phaddad@...dia.com>, 
 Raed Salem <raeds@...dia.com>, 
 Jianbo Liu <jianbol@...dia.com>, 
 Dragos Tatulea <dtatulea@...dia.com>, 
 Rahul Rameshbabu <rrameshbabu@...dia.com>, 
 Stanislav Fomichev <sdf@...ichev.me>, 
 Toke Høiland-Jørgensen <toke@...hat.com>, 
 Alexander Lobakin <aleksander.lobakin@...el.com>, 
 Jacob Keller <jacob.e.keller@...el.com>, 
 netdev@...r.kernel.org
Subject: Re: [PATCH v3 17/19] psp: provide decapsulation and receive helper
 for drivers

Daniel Zahka wrote:
> From: Raed Salem <raeds@...dia.com>
> 
> Create psp_rcv(), which drivers can call to psp decapsulate and attach
> a psp_skb_ext to an skb.
> 
> psp_rcv() only supports what the PSP architecture specification refers
> to as "transport mode" packets, where the L3 header is IPv6. psp_rcv()
> also assumes that a psp trailer is present and should be pulled from
> the skb.
> 
> Signed-off-by: Raed Salem <raeds@...dia.com>
> Signed-off-by: Rahul Rameshbabu <rrameshbabu@...dia.com>
> Signed-off-by: Daniel Zahka <daniel.zahka@...il.com>
> ---
> 
> Notes:
>     v3:
>     - patch introduced
> 
>  include/net/psp/functions.h |  1 +
>  net/psp/psp_main.c          | 49 +++++++++++++++++++++++++++++++++++++
>  2 files changed, 50 insertions(+)
> 
> diff --git a/include/net/psp/functions.h b/include/net/psp/functions.h
> index afb4f5929eec..8ecc396bcfff 100644
> --- a/include/net/psp/functions.h
> +++ b/include/net/psp/functions.h
> @@ -18,6 +18,7 @@ psp_dev_create(struct net_device *netdev, struct psp_dev_ops *psd_ops,
>  void psp_dev_unregister(struct psp_dev *psd);
>  bool psp_encapsulate(struct net *net, struct sk_buff *skb,
>  		     __be32 spi, u8 ver, __be16 sport);
> +int psp_rcv(struct sk_buff *skb, u16 dev_id, u8 generation);

If respinning, maybe prefix these device datapath helpers as psp_dev_.
>  
>  /* Kernel-facing API */
>  void psp_assoc_put(struct psp_assoc *pas);
> diff --git a/net/psp/psp_main.c b/net/psp/psp_main.c
> index 8229a004ba6e..ec60e06cdf69 100644
> --- a/net/psp/psp_main.c
> +++ b/net/psp/psp_main.c
> @@ -195,6 +195,55 @@ bool psp_encapsulate(struct net *net, struct sk_buff *skb,
>  }
>  EXPORT_SYMBOL(psp_encapsulate);
>  
> +/* Receive handler for PSP packets.
> + *
> + * Presently it accepts only already-authenticated packets and does not
> + * support optional fields, such as virtualization cookies.
> + */
> +int psp_rcv(struct sk_buff *skb, u16 dev_id, u8 generation)
> +{
> +	const struct psphdr *psph;
> +	int depth = 0, end_depth;
> +	struct psp_skb_ext *pse;
> +	struct ipv6hdr *ipv6h;
> +	struct ethhdr *eth;
> +	__be16 proto;
> +	u32 spi;
> +
> +	eth = (struct ethhdr *)(skb->data);
> +	proto = __vlan_get_protocol(skb, eth->h_proto, &depth);
> +	if (proto != htons(ETH_P_IPV6))
> +		return -EINVAL;
> +
> +	ipv6h = (struct ipv6hdr *)(skb->data + depth);
> +	depth += sizeof(*ipv6h);
> +	end_depth = depth + sizeof(struct udphdr) + sizeof(struct psphdr);
> +
> +	if (unlikely(end_depth > skb_headlen(skb)))
> +		return -EINVAL;
> +
> +	pse = skb_ext_add(skb, SKB_EXT_PSP);
> +	if (!pse)
> +		return -EINVAL;
> +
> +	psph = (const struct psphdr *)(skb->data + depth + sizeof(struct udphdr));
> +	pse->spi = psph->spi;
> +	pse->dev_id = dev_id;
> +	spi = ntohl(psph->spi);

unused

> +	pse->generation = generation;
> +	pse->version = FIELD_GET(PSPHDR_VERFL_VERSION, psph->verfl);
> +
> +	ipv6h->nexthdr = psph->nexthdr;
> +	ipv6h->payload_len =
> +		htons(ntohs(ipv6h->payload_len) - PSP_ENCAP_HLEN - PSP_TRL_SIZE);

Whether the trailer is removed by the device is device specific.

> +
> +	memmove(skb->data + PSP_ENCAP_HLEN, skb->data, depth);
> +	skb_pull(skb, PSP_ENCAP_HLEN);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL(psp_rcv);
> +
>  static int __init psp_init(void)
>  {
>  	mutex_init(&psp_devs_lock);
> -- 
> 2.47.1
>