From 2c8f025c5d59ba385ea80c202c2fbfebaceaeb3f Mon Sep 17 00:00:00 2001 From: Lindsay Stewart Date: Mon, 25 Sep 2023 14:35:09 -0700 Subject: [PATCH] ktls: release APIs as unstable (#4217) --- api/unstable/ktls.h | 115 +++++++++++++++++++++++++++++ bindings/rust/generate/src/main.rs | 2 +- tls/s2n_ktls.h | 1 + 3 files changed, 117 insertions(+), 1 deletion(-) create mode 100644 api/unstable/ktls.h diff --git a/api/unstable/ktls.h b/api/unstable/ktls.h new file mode 100644 index 00000000000..f963130fe6d --- /dev/null +++ b/api/unstable/ktls.h @@ -0,0 +1,115 @@ +/* +* Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved. +* +* Licensed under the Apache License, Version 2.0 (the "License"). +* You may not use this file except in compliance with the License. +* A copy of the License is located at +* +* http://aws.amazon.com/apache2.0 +* +* or in the "license" file accompanying this file. This file is distributed +* on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either +* express or implied. See the License for the specific language governing +* permissions and limitations under the License. +*/ + +#pragma once + +#include + +/** + * @file ktls.h + * + * The following APIs enable applications to use kernel TLS (kTLS), meaning that + * encrypting and decrypting TLS records is handled by the kernel rather than by + * the s2n-tls library. + * + * The kTLS APIs are currently considered unstable. kTLS is a relatively new + * feature with limited and volatile support from different kernels and hardware. + * + * Currently, s2n-tls supports ktls for only very limited scenarios: + * - You must be using Linux. We have not tested with other kernels. + * - Your kernel must support kTLS. For Linux, versions >4.13 should support kTLS. + * - The TLS kernel module must be enabled. While some environments enable the + * module by default, most will require you to run `sudo modprobe tls`. + * - You must negotiate TLS1.2. TLS1.3 support is blocked on kernel support for + * TLS KeyUpdate messages. + * - You must negotiate AES128-GCM, which is the most preferred cipher suite + * in the "default" security policy. Other ciphers are supported by the kernel, + * but not implemented in s2n-tls yet. + */ + +/** + * Enables sending using kTLS on a given connection. + * + * See above for the limitations on when kTLS can be enabled. Additionally, + * s2n_connection_ktls_enable_send must be called after the handshake completes. + * It may be called after some application data is sent and received without kTLS, + * but there must be no pending application data that requires flushing. If these + * requirements are not met, enabling kTLS will fail with an error. + * + * After kTLS is enabled for sending, s2n_send, s2n_sendv, and s2n_sendv_with_offset + * will use kTLS. kTLS should result in memory and CPU savings. s2n_sendfile will + * also become available. + * + * For applications using kTLS to avoid copying or allocating memory, s2n_sendv + * should be preferred over s2n_sendv_with_offset. For s2n_sendv_with_offset, + * s2n-tls may need to copy the provided iovec array to apply the offset, and may + * need to allocate memory to copy large (>16) iovec arrays. + * + * If kTLS is enabled for sending, s2n_connection_get_wire_bytes_out will always + * return 0 instead of an accurate count. + * + * @warning Due to the uncertainty around kTLS support, the signature of this + * method is likely to change before kTLS is marked as stable. + * + * @param conn A pointer to the connection. + * @returns S2N_SUCCESS if kTLS is successfully enabled. If kTlS is not successfully + * enabled, returns S2N_FAILURE but the connection may proceed without kTLS. + */ +S2N_API int s2n_connection_ktls_enable_send(struct s2n_connection *conn); + +/** + * Enables receiving using kTLS on a given connection. + * + * See above for the limitations on when kTLS can be enabled. Additionally, + * s2n_connection_ktls_enable_recv must be called after the handshake completes. + * It may be called after some application data is sent and received without kTLS, + * but there must be no buffered application data that requires draining. If these + * requirements are not met, enabling kTLS will fail with an error. + * + * After kTLS is enabled for receiving, s2n_recv will use kTLS. This may result + * in memory and CPU savings, but currently will still buffer and copy application data. + * We will further optimize s2n_recv for kTLS in the future. + * + * If kTLS is enabled for receiving, s2n_connection_get_wire_bytes_in will always + * return 0 instead of an accurate count. + * + * @warning Due to the uncertainty around kTLS support, the signature of this + * method is likely to change before kTLS is marked as stable. + * + * @param conn A pointer to the connection. + * @returns S2N_SUCCESS if kTLS is successfully enabled. If kTlS is not successfully + * enabled, returns S2N_FAILURE but the connection may proceed without kTLS. + */ +S2N_API int s2n_connection_ktls_enable_recv(struct s2n_connection *conn); + +/** + * Sends the contents of a file as application data. + * + * s2n_sendfile should be more efficient than s2n_send because the copy between + * the file and the write socket happens inside the kernel. + * + * This method is only supported if kTLS is enabled for sending. + * + * @param conn A pointer to the connection. + * @param fd The file descriptor to read from. It must be opened for reading and + * support mmap-like operations (i.e., it cannot be a socket). + * @param offset The offset in the file to begin reading at. + * @param count The maximum number of bytes to read from the file. + * @param bytes_written Will be set to the number of bytes written if successful. + * @param blocked Will be set to the blocked status if an `S2N_ERR_T_BLOCKED` error is returned. + * @returns S2N_SUCCESS if any bytes are successfully written, S2N_FAILURE otherwise. + */ +S2N_API int s2n_sendfile(struct s2n_connection *conn, int fd, off_t offset, size_t count, + size_t *bytes_written, s2n_blocked_status *blocked); diff --git a/bindings/rust/generate/src/main.rs b/bindings/rust/generate/src/main.rs index b097d349e8d..157ad3abe61 100644 --- a/bindings/rust/generate/src/main.rs +++ b/bindings/rust/generate/src/main.rs @@ -124,7 +124,7 @@ const COPYRIGHT: &str = r#" const PRELUDE: &str = r#" #![allow(unused_imports, non_camel_case_types)] -use libc::{iovec, FILE}; +use libc::{iovec, FILE, off_t}; "#; fn base_builder() -> bindgen::Builder { diff --git a/tls/s2n_ktls.h b/tls/s2n_ktls.h index 768d9a88fac..c41a0796d2b 100644 --- a/tls/s2n_ktls.h +++ b/tls/s2n_ktls.h @@ -17,6 +17,7 @@ #include +#include "api/unstable/ktls.h" #include "tls/s2n_connection.h" /* Define headers needed to enable and use kTLS. *