On 7/29/25 11:41, Wilfred Mallawa wrote:
> From: Wilfred Mallawa <wilfred.mallawa@xxxxxxx>
>
> During a handshake, an endpoint may specify a maximum record size limit.
> Currently, this limit is not visble to the kernel particularly in the case
> where userspace handles the handshake (tlshd/gnutls). This patch adds
> support for retrieving the record size limit.
>
> This is the first step in ensuring that the kernel can respect the record
> size limit imposed by the endpoint.
>
> Signed-off-by: Wilfred Mallawa <wilfred.mallawa@xxxxxxx>
> ---
> Documentation/netlink/specs/handshake.yaml | 3 +++
> Documentation/networking/tls-handshake.rst | 8 +++++++-
> drivers/nvme/host/tcp.c | 3 ++-
> drivers/nvme/target/tcp.c | 3 ++-
> include/net/handshake.h | 4 +++-
> include/uapi/linux/handshake.h | 1 +
> net/handshake/genl.c | 5 +++--
> net/handshake/tlshd.c | 15 +++++++++++++--
> net/sunrpc/svcsock.c | 4 +++-
> net/sunrpc/xprtsock.c | 4 +++-
> 10 files changed, 40 insertions(+), 10 deletions(-)
>
> diff --git a/Documentation/netlink/specs/handshake.yaml b/Documentation/netlink/specs/handshake.yaml
> index b934cc513e3d..35d5eb91a3f9 100644
> --- a/Documentation/netlink/specs/handshake.yaml
> +++ b/Documentation/netlink/specs/handshake.yaml
> @@ -84,6 +84,9 @@ attribute-sets:
> name: remote-auth
> type: u32
> multi-attr: true
> + -
> + name: record-size-limit
> + type: u32
>
> operations:
> list:
> diff --git a/Documentation/networking/tls-handshake.rst b/Documentation/networking/tls-handshake.rst
> index 6f5ea1646a47..cd984a137779 100644
> --- a/Documentation/networking/tls-handshake.rst
> +++ b/Documentation/networking/tls-handshake.rst
> @@ -169,7 +169,8 @@ The synopsis of this function is:
> .. code-block:: c
>
> typedef void (*tls_done_func_t)(void *data, int status,
> - key_serial_t peerid);
> + key_serial_t peerid,
> + size_t tls_record_size_limit);
>
> The consumer provides a cookie in the @ta_data field of the
> tls_handshake_args structure that is returned in the @data parameter of
> @@ -200,6 +201,11 @@ The @peerid parameter contains the serial number of a key containing the
> remote peer's identity or the value TLS_NO_PEERID if the session is not
> authenticated.
>
> +The @tls_record_size_limit parameter, if non-zero, exposes the tls max
> +record size advertised by the endpoint. Record size must not exceed this amount.
> +A negative value shall indicate that the endpoint did not advertise the
> +maximum record size limit.
size_t cannot be negative... Did you mean:
"A value of 0 (TLS_NO_RECORD_SIZE_LIMIT)..."
Also note that even if the endpoint does not advertize a record sie limit, we
still have one (16K was it ?). So I think that the name TLS_NO_RECORD_SIZE_LIMIT
is a little misleading.
> +
> A best practice is to close and destroy the socket immediately if the
> handshake failed.
[...]
> diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
> index e1c85123b445..2014d906ff06 100644
> --- a/net/sunrpc/svcsock.c
> +++ b/net/sunrpc/svcsock.c
> @@ -417,13 +417,15 @@ static void svc_tcp_kill_temp_xprt(struct svc_xprt *xprt)
> * @data: address of xprt to wake
> * @status: status of handshake
> * @peerid: serial number of key containing the remote peer's identity
> + * @tls_record_size_limit: Max tls_record_size_limit of the endpoint
Please make a proper sentence to describe tls_record_size_limit instead of
repeating that argument name.
> *
> * If a security policy is specified as an export option, we don't
> * have a specific export here to check. So we set a "TLS session
> * is present" flag on the xprt and let an upper layer enforce local
> * security policy.
> */
> -static void svc_tcp_handshake_done(void *data, int status, key_serial_t peerid)
> +static void svc_tcp_handshake_done(void *data, int status, key_serial_t peerid,
> + size_t tls_record_size_limit)
> {
> struct svc_xprt *xprt = data;
> struct svc_sock *svsk = container_of(xprt, struct svc_sock, sk_xprt);
> diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
> index 04ff66758fc3..509aa6269b0a 100644
> --- a/net/sunrpc/xprtsock.c
> +++ b/net/sunrpc/xprtsock.c
> @@ -2569,9 +2569,11 @@ static int xs_tcp_tls_finish_connecting(struct rpc_xprt *lower_xprt,
> * @data: address of xprt to wake
> * @status: status of handshake
> * @peerid: serial number of key containing the remote's identity
> + * @tls_record_size_limit: Max tls_record_size_limit of the endpoint
Same here.
> *
> */
> -static void xs_tls_handshake_done(void *data, int status, key_serial_t peerid)
> +static void xs_tls_handshake_done(void *data, int status, key_serial_t peerid,
> + size_t tls_record_size_limit)
> {
> struct rpc_xprt *lower_xprt = data;
> struct sock_xprt *lower_transport =
--
Damien Le Moal
Western Digital Research
