Add missing documentation for the TLS_TX_ZEROCOPY_RO opt-in. Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx> --- CC: corbet@xxxxxxx CC: linux-doc@xxxxxxxxxxxxxxx --- Documentation/networking/tls.rst | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/Documentation/networking/tls.rst b/Documentation/networking/tls.rst index 8cb2cd4e2a80..be8e10c14b05 100644 --- a/Documentation/networking/tls.rst +++ b/Documentation/networking/tls.rst @@ -214,6 +214,31 @@ of calling send directly after a handshake using gnutls. Since it doesn't implement a full record layer, control messages are not supported. +Optional optimizations +---------------------- + +There are certain condition-specific optimizations the TLS ULP can make, +if requested. Those optimizations are either not universally beneficial +or may impact correctness, hence they require an opt-in. +All options are set per-socket using setsockopt(), and their +state can be checked using getsockopt() and via socket diag (``ss``). + +TLS_TX_ZEROCOPY_RO +~~~~~~~~~~~~~~~~~~ + +For device offload only. Allow sendfile() data to be transmitted directly +to the NIC without making an in-kernel copy. This allows true zero-copy +behavior when device offload is enabled. + +The application must make sure that the data is not modified between being +submitted and transmission completing. In other words this is mostly +applicable if the data sent on a socket via sendfile() is read-only. + +Modifying the data may result in different versions of the data being used +for the original TCP transmission and TCP retransmissions. To the receiver +this will look like TLS records had been tampered with and will result +in record authentication failures. + Statistics ========== -- 2.36.1
