RE: [PATCH v6 3/4] virtio-net: extend virtio_net_hdr for IPsec support

> From: Srujana Challa <[email protected]>
> Sent: Tuesday, April 29, 2025 6:10 PM
> 
> Add IPsec resource object identifiers to the virtio_net_hdr for identifying
> encryption/decryption operations on tx and rx side respectively, along with
> flags.
> 
> Signed-off-by: Srujana Challa <[email protected]>
> ---
>  device-types/net/description.tex | 51
> ++++++++++++++++++++++++++++++--
>  1 file changed, 48 insertions(+), 3 deletions(-)
> 
> diff --git a/device-types/net/description.tex b/device-
> types/net/description.tex
> index 105a002..2540f2b 100644
> --- a/device-types/net/description.tex
> +++ b/device-types/net/description.tex
> @@ -597,6 +597,9 @@ \subsection{Device Operation}\label{sec:Device
> Types / Network Device / Device O
>  #define VIRTIO_NET_HDR_F_DATA_VALID    2
>  #define VIRTIO_NET_HDR_F_RSC_INFO      4
>  #define VIRTIO_NET_HDR_F_UDP_TUNNEL_CSUM 8
> +#define VIRTIO_NET_HDR_F_SECURITY      16
> +#define VIRTIO_NET_HDR_F_SECURITY_ERR  32 #define
> +VIRTIO_NET_HDR_F_SECURITY_SA_SOFT_EXPIRY_WARN 64
>          u8 flags;
>  #define VIRTIO_NET_HDR_GSO_NONE        0
>  #define VIRTIO_NET_HDR_GSO_TCPV4       1
> @@ -618,7 +621,11 @@ \subsection{Device Operation}\label{sec:Device
> Types / Network Device / Device O
>          le16 outer_th_offset    (Only if VIRTIO_NET_F_HOST_UDP_TUNNEL_GSO
> or VIRTIO_NET_F_GUEST_UDP_TUNNEL_GSO negotiated)
>          le16 inner_nh_offset;   (Only if VIRTIO_NET_F_HOST_UDP_TUNNEL_GSO
> or VIRTIO_NET_F_GUEST_UDP_TUNNEL_GSO negotiated)
>          le16 outer_nh_offset;   /* Only if VIRTIO_NET_F_OUT_NET_HEADER
> negotiated */
> -        u8 padding_reserved_2[6]; /* Only if VIRTIO_NET_F_OUT_NET_HEADER
> negotiated */
> +        /* Only if VIRTIO_NET_F_IPSEC negotiated */

> +        /* Only if VIRTIO_NET_F_OUT_NET_HEADER or VIRTIO_NET_F_IPSEC negotiated */
This should be,
union {
	u8 padding_reserved_2[6];
	struct ipsec_resource_hdr {
                 le32 resource_id;
                 le16 resource_type;
              } ipsec_resource_hdr;
  };

>  \end{lstlisting}
> 
> @@ -972,6 +979,15 @@ \subsubsection{Packet
> Transmission}\label{sec:Device Types / Network Device / De  together with the
> VIRTIO_NET_HDR_F_GSO_UDP_TUNNEL_IPV4 bit or the
>  VIRTIO_NET_HDR_F_GSO_UDP_TUNNEL_IPV6 bit in \field{gso_type}.
> 
> +If the device supports \hyperref[par:Device Types / Network Device /
> +Device Operation / IPsec Operation]{IPsec Operation}, the driver may set
> VIRTIO_NET_HDR_F_SECURITY bit in \field{flags}, if so:
> +\begin{enumerate}
> +\item the driver MUST create IPsec Outbound resource object
> +\hyperref[par:Device Types / Crypto Device / Device Operation / IPsec
> +Service Operation / Resource objects /
> +VIRTIO-CRYPTO-RESOURCE-OBJ-IPSEC-ENC-
> SA]{VIRTIO_NET_RESOURCE_OBJ_IPSEC_
> +OUTB_SA} \item the driver MUST set \field{resource_id} to a valid IPsec
> +outbound
> +      resource object ID.
> +\end{enumerate}
> +
>  \devicenormative{\paragraph}{Packet Transmission}{Device Types / Network
> Device / Device Operation / Packet Transmission}  The device MUST ignore
> \field{flag} bits that it does not recognize.
> 
> @@ -1032,6 +1048,10 @@ \subsubsection{Packet
> Transmission}\label{sec:Device Types / Network Device / De
> 
>  If VIRTIO_NET_HDR_F_NEEDS_CSUM is not set, the device MUST NOT  rely on
> the packet checksum being correct.
> +
> +If VIRTIO_NET_HDR_F_SECURITY bit in \field{flags} is not set, the
> +device MUST NOT use the \field{resource_id} and \field{resource_type}.
> +
>  \paragraph{Packet Transmission Interrupt}\label{sec:Device Types / Network
> Device / Device Operation / Packet Transmission / Packet Transmission
> Interrupt}
> 
>  Often a driver will suppress transmission virtqueue interrupts @@ -1084,8
> +1104,8 @@ \subsubsection{Setting Up Receive Buffers}\label{sec:Device
> Types / Network Devi  \end{note}
> 
>  When calculating the size of \field{struct virtio_net_hdr}, the driver -MUST
> consider all the fields inclusive up to \field{padding_reserved_2}, -i.e. 32 bytes
> if VIRTIO_NET_F_OUT_NET_HEADER is negotiated or up to
> \field{inner_nh_offset}
> +MUST consider all the fields inclusive up to \field{struct
> +ipsec_resource_hdr}, i.e. 32 bytes if VIRTIO_NET_F_OUT_NET_HEADER or
> +VIRTIO_NET_F_IPSEC is negotiated or up to \field{inner_nh_offset}
>  i.e. 24 bytes if VIRTIO_NET_F_HOST_UDP_TUNNEL_GSO is negotiated or up
> to \field{padding_reserved}  i.e. 20 bytes if VIRTIO_NET_F_HASH_REPORT is
> negotiated, and 12 bytes if not.
> 
Please change the wording to refer to padding or ipsec_resource_hdr accordingly.

> @@ -1341,6 +1361,21 @@ \subsubsection{Processing of Incoming
> Packets}\label{sec:Device Types / Network  \field{flags}, the device MUST
> either provide a zero outer UDP header  checksum or a fully checksummed
> outer UDP header.
> 
> +The device MUST set the VIRTIO_NET_HDR_F_SECURITY bit in the
> +\field{flags} if the packet goes through the IPsec processing.
> +Otherwise, this bit MUST be cleared. The device MUST set or clear this
> +bit regardless of setting VIRTIO_NET_HDR_F_SECURITY_ERR or
> VIRTIO_NET_HDR_F_SECURITY_SA_SOFT_EXPIRY_WARN bit.
> +
> +The device MUST set the VIRTIO_NET_HDR_F_SECURITY_ERR bit in the
> +\field{flags} if any error is encountered during IPsec processing. Otherwise,
> this bit MUST be cleared.
> +The device MUST set or clear this bit regardless of setting
> +VIRTIO_NET_HDR_F_SECURITY_SA_SOFT_EXPIRY_WARN bit.
> +
> +The device MUST set the
> VIRTIO_NET_HDR_F_SECURITY_SA_SOFT_EXPIRY_WARN
> +bit in the \field{flags} if the SA associated with \field{resource_id}
> +reaches the SA lifetime soft limits configured in the \field{struct
> virtio_crypto_ipsec_lifetime}.
> +See \hyperref[par:Device Types / Crypto Device / Device Operation / IPsec
> Service Operation / Resource objects / VIRTIO-CRYPTO-RESOURCE-OBJ-IPSEC-
> OUTBOUND-SA]{VIRTIO_NET_RESOURCE_OBJ_IPSEC_OUTB_SA}.
> +
>  \drivernormative{\paragraph}{Processing of Incoming  Packets}{Device Types
> / Network Device / Device Operation /  Processing of Incoming Packets} @@ -
> 1392,6 +1427,12 @@ \subsubsection{Processing of Incoming
> Packets}\label{sec:Device Types / Network
>  VIRTIO_NET_HDR_GSO_UDP_TUNNEL_IPV6 in \field{gso_type} are not set,
> the driver MOST NOT accept the packet.
> 
> +When VIRTIO_NET_HDR_F_SECURITY and
> VIRTIO_NET_HDR_F_SECURITY_ERR bits
> +are set in the \field{flags}, it indicates that the device experienced a
> processing error on the IPsec packet.
> +It need not be an 'error packet'. For example, a particular SA was not
> +offloaded or SA has reached the SA lifetime hard limits configured in the
> \field{struct virtio_crypto_ipsec_lifetime}.
> +So vnet_hdr will have both bits set.
> +
>  \paragraph{Hash calculation for incoming packets}  \label{sec:Device Types /
> Network Device / Device Operation / Processing of Incoming Packets / Hash
> calculation for incoming packets}
> 
> @@ -3528,6 +3569,10 @@ \subsubsection{IPsec
> Operation}\label{sec:Device Types / Network Device / Device  See
> \ref{sec:Device Types / Network Device / Device Operation / Flow filter}  for
> details about flow filter.
> 
> +Note that there is a small race condition where a SA object might be
> +destroyed while a recieve packet is still inflight. The driver SHOULD
> +handle this situation appropriately.
> +
>  \paragraph{Device and driver capabilities}  \label{par:Device Types / Network
> Device / Device Operation / IPsec Operation / Device and driver capabilities}
> 
> --
> 2.25.1

For the rest of the content of this patch:
Reviewed-by: Parav Pandit <[email protected]>