Re: [PATCH v6 2/2] net/tls: Add kernel APIs for requesting a TLSv1.3 handshake

Chuck Lever III
2023-03-10T16:51:33Z

> On Mar 3, 2023, at 1:51 PM, Chuck Lever <cel@kernel.org> wrote:
>
> From: Chuck Lever <chuck.lever@oracle.com>
>
> To enable kernel consumers of TLS to request a TLS handshake, add
> support to net/tls/ to request a handshake upcall.
>
> This patch also acts as a template for adding handshake upcall
> support to other kernel transport layer security providers.
>
> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
> ---
> Documentation/netlink/specs/handshake.yaml | 4
> Documentation/networking/index.rst | 1
> Documentation/networking/tls-handshake.rst | 219 ++++++++++++++++
> include/net/tls.h | 29 ++
> include/uapi/linux/handshake.h | 2
> net/handshake/netlink.c | 1
> net/tls/Makefile | 2
> net/tls/tls_handshake.c | 391 ++++++++++++++++++++++++++++
> 8 files changed, 647 insertions(+), 2 deletions(-)
> create mode 100644 Documentation/networking/tls-handshake.rst
> create mode 100644 net/tls/tls_handshake.c
>
> diff --git a/Documentation/netlink/specs/handshake.yaml b/Documentation/netlink/specs/handshake.yaml
> index 8367f50fb745..49c3bd9ca6a9 100644
> --- a/Documentation/netlink/specs/handshake.yaml
> +++ b/Documentation/netlink/specs/handshake.yaml
> @@ -21,7 +21,7 @@ definitions:
> name: handler-class
> enum-name:
> value-start: 0
> - entries: [ none ]
> + entries: [ none, tlshd ]
> -
> type: enum
> name: msg-type
> @@ -135,3 +135,5 @@ mcast-groups:
> list:
> -
> name: none
> + -
> + name: tlshd
> diff --git a/Documentation/networking/index.rst b/Documentation/networking/index.rst
> index 4ddcae33c336..189517f4ea96 100644
> --- a/Documentation/networking/index.rst
> +++ b/Documentation/networking/index.rst
> @@ -36,6 +36,7 @@ Contents:
> scaling
> tls
> tls-offload
> + tls-handshake
> nfc
> 6lowpan
> 6pack
> diff --git a/Documentation/networking/tls-handshake.rst b/Documentation/networking/tls-handshake.rst
> new file mode 100644
> index 000000000000..0580e4d1b67c
> --- /dev/null
> +++ b/Documentation/networking/tls-handshake.rst
> @@ -0,0 +1,219 @@
> +.. SPDX-License-Identifier: GPL-2.0
> +
> +=======================
> +In-Kernel TLS Handshake
> +=======================
> +
> +Overview
> +========
> +
> +Transport Layer Security (TLS) is a Upper Layer Protocol (ULP) that runs
> +over TCP. TLS provides end-to-end data integrity and confidentiality in
> +addition to peer authentication.
> +
> +The kernel's kTLS implementation handles the TLS record subprotocol, but
> +does not handle the TLS handshake subprotocol which is used to establish
> +a TLS session. Kernel consumers can use the API described here to
> +request TLS session establishment.
> +
> +There are several possible ways to provide a handshake service in the
> +kernel. The API described here is designed to hide the details of those
> +implementations so that in-kernel TLS consumers do not need to be
> +aware of how the handshake gets done.
> +
> +
> +User handshake agent
> +====================
> +
> +As of this writing, there is no TLS handshake implementation in the
> +Linux kernel. To provide a handshake service, a handshake agent
> +(typically in user space) is started in each network namespace where a
> +kernel consumer might require a TLS handshake. Handshake agents listen
> +for events sent from the kernel that indicate a handshake request is
> +waiting.
> +
> +An open socket is passed to a handshake agent via a netlink operation,
> +which creates a socket descriptor in the agent's file descriptor table.
> +If the handshake completes successfully, the handshake agent promotes
> +the socket to use the TLS ULP and sets the session information using the
> +SOL_TLS socket options. The handshake agent returns the socket to the
> +kernel via a second netlink operation.
> +
> +
> +Kernel Handshake API
> +====================
> +
> +A kernel TLS consumer initiates a client-side TLS handshake on an open
> +socket by invoking one of the tls_client_hello() functions. First, it
> +fills in a structure that contains the parameters of the request:
> +
> +.. code-block:: c
> +
> +struct tls_handshake_args {
> + struct socket *ta_sock;
> + tls_done_func_t ta_done;
> + void *ta_data;
> + unsigned int ta_timeout_ms;
> + key_serial_t ta_keyring;
> + key_serial_t ta_my_peerid;
> + key_serial_t ta_my_privkey;
> +};
> +
> +The @ta_sock field references an open and connected socket. The consumer
> +must hold a reference on the socket to prevent it from being destroyed
> +while the handshake is in progress. The consumer must also have
> +instantiated a struct file in sock->file.
> +
> +
> +@ta_done contains a callback function that is invoked when the handshake
> +has completed. Further explanation of this function is in the "Handshake
> +Completion" sesction below.
> +
> +The consumer can fill in the @ta_timeout_ms field to force the servicing
> +handshake agent to exit after a number of milliseconds. This enables the
> +socket to be fully closed once both the kernel and the handshake agent
> +have closed their endpoints.
> +
> +Authentication material such as x.509 certificates, private certificate
> +keys, and pre-shared keys are provided to the handshake agent in keys
> +that are instantiated by the consumer before making the handshake
> +request. The consumer can provide a private keyring that is linked into
> +the handshake agent's process keyring in the @ta_keyring field to prevent
> +access of those keys by other subsystems.
> +
> +The use of the @ta_my_peerid and @ta_my_privkey fields depends on which
> +authentication mode is requested. For example to start an x.509-
> +authenticated TLS session:
> +
> +.. code-block:: c
> +
> + ret = tls_client_hello_x509(args, gfp_flags);
> +
> +The function returns zero when the handshake request is under way. A
> +zero return guarantees the callback function @ta_done will be invoked
> +for this socket. The function returns a negative errno if the handshake
> +could not be started. A negative errno guarantees the callback function
> +@ta_done will not be invoked on this socket.
> +
> +The handshake argument structure is filled in as above. The consumer
> +fills in the @ta_my_peerid field with the serial number of a key that
> +contains an x.509 certificate. The consumer fills in the @ta_my_privkey
> +field with the serial number of a key that contains the private key for
> +that certificate.
> +
> +
> +To initiate a client-side TLS handshake with a pre-shared key, use:
> +
> +.. code-block:: c
> +
> + ret = tls_client_hello_psk(args, gfp_flags);
> +
> +In this case, the consumer fills in the @ta_my_peerid field with the
> +serial number of a key that contains a pre-shared key to be used for the
> +handshake. The other fields are filled in as above.
> +
> +
> +To initiate an anonymous client-side TLS handshake use:
> +
> +.. code-block:: c
> +
> + ret = tls_client_hello_anon(args, gfp_flags);
> +
> +The handshake agent presents no peer identity information to the remote
> +during this type of handshake. Only server authentication (ie the client
> +verifies the server's identity) is performed during the handshake. Thus
> +the established session uses encryption only.
> +
> +
> +Consumers that are in-kernel servers use:
> +
> +.. code-block:: c
> +
> + ret = tls_server_hello_x509(args, gfp_flags);
> +
> +or
> +
> +.. code-block:: c
> +
> + ret = tls_server_hello_psk(args, gfp_flags);
> +
> +The argument structure is filled in as above.
> +
> +
> +If the consumer needs to cancel the handshake request, say, due to a ^C
> +or other exigent event, the consumer can invoke:
> +
> +.. code-block:: c
> +
> + bool tls_handshake_cancel(sock);
> +
> +This function returns true if the handshake request associated with
> +@sock has been canceled. The consumer's handshake completion callback
> +will not be invoked. If this function returns false, then the consumer's
> +completion callback has already been invoked.
> +
> +
> +Handshake Completion
> +====================
> +
> +When the handshake agent has completed processing, it notifies the
> +kernel that the socket may be used by the consumer again. At this point,
> +the consumer's handshake completion callback, provided in the @ta_done
> +field in the tls_handshake_args structure, is invoked.
> +
> +The synopsis of this function is:
> +
> +.. code-block:: c
> +
> +typedef void (*tls_done_func_t)(void *data, int status,
> + key_serial_t peerid);
> +
> +The consumer provides a cookie in the @ta_data field of the
> +tls_handshake_args structure that is returned in the @data parameter of
> +this callback. The consumer uses the cookie to match the callback to the
> +thread waiting for the handshake to complete.
> +
> +The success status of the handshake is returned via the @status
> +parameter:
> +
> ++-----------+----------------------------------------------+
> +| errno | meaning |
> ++===========+==============================================+
> +| 0 | TLS session established successfully |
> ++-----------+----------------------------------------------+
> +| EACCESS | Remote peer rejected the handshake or |
> +| | authentication failed |
> ++-----------+----------------------------------------------+
> +| ENOMEM | Temporary resource allocation failure |
> ++-----------+----------------------------------------------+
> +| EINVAL | Consumer provided an invalid argument |
> ++-----------+----------------------------------------------+
> +| ENOKEY | Missing authentication material |
> ++-----------+----------------------------------------------+
> +| EIO | An unexpected fault occurred |
> ++-----------+----------------------------------------------+
> +
> +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.
> +
> +A best practice is to close and destroy the socket immediately if the
> +handshake failed.
> +
> +
> +Other considerations
> +--------------------
> +
> +While a handshake is under way, the kernel consumer must alter the
> +socket's sk_data_ready callback function to ignore all incoming data.
> +Once the handshake completion callback function has been invoked, normal
> +receive operation can be resumed.
> +
> +Once a TLS session is established, the consumer must provide a buffer
> +for and then examine the control message (CMSG) that is part of every
> +subsequent sock_recvmsg(). Each control message indicates whether the
> +received message data is TLS record data or session metadata.
> +
> +See tls.rst for details on how a kTLS consumer recognizes incoming
> +(decrypted) application data, alerts, and handshake packets once the
> +socket has been promoted to use the TLS ULP.
> diff --git a/include/net/tls.h b/include/net/tls.h
> index 154949c7b0c8..c8a964a62ded 100644
> --- a/include/net/tls.h
> +++ b/include/net/tls.h
> @@ -512,4 +512,33 @@ static inline bool tls_is_sk_rx_device_offloaded(struct sock *sk)
> return tls_get_ctx(sk)->rx_conf == TLS_HW;
> }
> #endif
> +
> +enum {
> + TLS_NO_KEYRING = 0,
> + TLS_NO_PEERID = 0,
> + TLS_NO_CERT = 0,
> + TLS_NO_PRIVKEY = 0,
> +};
> +
> +typedef void (*tls_done_func_t)(void *data, int status,
> + key_serial_t peerid);
> +
> +struct tls_handshake_args {
> + struct socket *ta_sock;
> + tls_done_func_t ta_done;
> + void *ta_data;
> + unsigned int ta_timeout_ms;
> + key_serial_t ta_keyring;
> + key_serial_t ta_my_peerid;
> + key_serial_t ta_my_privkey;
> +};
> +
> +int tls_client_hello_anon(const struct tls_handshake_args *args, gfp_t flags);
> +int tls_client_hello_x509(const struct tls_handshake_args *args, gfp_t flags);
> +int tls_client_hello_psk(const struct tls_handshake_args *args, gfp_t flags);
> +int tls_server_hello_x509(const struct tls_handshake_args *args, gfp_t flags);
> +int tls_server_hello_psk(const struct tls_handshake_args *args, gfp_t flags);
> +
> +bool tls_handshake_cancel(struct socket *sock);

When TLS handshake consumers are built-in but TLS is built
as a module, these API calls become undefined references:

ld: net/sunrpc/xprtsock.o: in function `xs_tls_handshake_sync':
/home/cel/src/linux/linux/net/sunrpc/xprtsock.c:2560: undefined reference to `tls_client_hello_x509'
ld: /home/cel/src/linux/linux/net/sunrpc/xprtsock.c:2552: undefined reference to `tls_client_hello_anon'
ld: /home/cel/src/linux/linux/net/sunrpc/xprtsock.c:2572: undefined reference to `tls_handshake_cancel'
ld: net/sunrpc/xprtsock.o: in function `xs_reset_transport':
/home/cel/src/linux/linux/net/sunrpc/xprtsock.c:1257: undefined reference to `tls_handshake_cancel'
ld: net/sunrpc/svcsock.o: in function `svc_tcp_handshake':
/home/cel/src/linux/linux/net/sunrpc/svcsock.c:449: undefined reference to `tls_server_hello_x509'
ld: /home/cel/src/linux/linux/net/sunrpc/svcsock.c:458: undefined reference to `tls_handshake_cancel'

This was fine for our prototype: we just don't build it that
way. But it won't work long-term.

What is the approach that would be most acceptable to address
this?

> +
> #endif /* _TLS_OFFLOAD_H */
> diff --git a/include/uapi/linux/handshake.h b/include/uapi/linux/handshake.h
> index 6e0c608a6b91..fe888abb4be8 100644
> --- a/include/uapi/linux/handshake.h
> +++ b/include/uapi/linux/handshake.h
> @@ -11,6 +11,7 @@
>
> enum {
> HANDSHAKE_HANDLER_CLASS_NONE,
> + HANDSHAKE_HANDLER_CLASS_TLSHD,
> };
>
> enum {
> @@ -67,5 +68,6 @@ enum {
> };
>
> #define HANDSHAKE_MCGRP_NONE "none"
> +#define HANDSHAKE_MCGRP_TLSHD "tlshd"
>
> #endif /* _UAPI_LINUX_HANDSHAKE_H */
> diff --git a/net/handshake/netlink.c b/net/handshake/netlink.c
> index 6f3a7852742b..454063bdd645 100644
> --- a/net/handshake/netlink.c
> +++ b/net/handshake/netlink.c
> @@ -260,6 +260,7 @@ static const struct genl_split_ops handshake_nl_ops[] = {
>
> static const struct genl_multicast_group handshake_nl_mcgrps[] = {
> [HANDSHAKE_HANDLER_CLASS_NONE] = { .name = HANDSHAKE_MCGRP_NONE, },
> + [HANDSHAKE_HANDLER_CLASS_TLSHD] = { .name = HANDSHAKE_MCGRP_TLSHD, },
> };
>
> static struct genl_family __ro_after_init handshake_genl_family = {
> diff --git a/net/tls/Makefile b/net/tls/Makefile
> index e41c800489ac..7e56b57f14f6 100644
> --- a/net/tls/Makefile
> +++ b/net/tls/Makefile
> @@ -7,7 +7,7 @@ CFLAGS_trace.o := -I$(src)
>
> obj-$(CONFIG_TLS) += tls.o
>
> -tls-y := tls_main.o tls_sw.o tls_proc.o trace.o tls_strp.o
> +tls-y := tls_handshake.o tls_main.o tls_sw.o tls_proc.o trace.o tls_strp.o
>
> tls-$(CONFIG_TLS_TOE) += tls_toe.o
> tls-$(CONFIG_TLS_DEVICE) += tls_device.o tls_device_fallback.o
> diff --git a/net/tls/tls_handshake.c b/net/tls/tls_handshake.c
> new file mode 100644
> index 000000000000..a7ac923b0d6b
> --- /dev/null
> +++ b/net/tls/tls_handshake.c
> @@ -0,0 +1,391 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Establish a TLS session for a kernel socket consumer
> + *
> + * Author: Chuck Lever <chuck.lever@oracle.com>
> + *
> + * Copyright (c) 2021-2023, Oracle and/or its affiliates.
> + */
> +
> +#include <linux/types.h>
> +#include <linux/socket.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/slab.h>
> +#include <linux/key.h>
> +
> +#include <net/sock.h>
> +#include <net/tls.h>
> +#include <net/genetlink.h>
> +#include <net/handshake.h>
> +
> +#include <uapi/linux/keyctl.h>
> +#include <uapi/linux/handshake.h>
> +
> +struct tls_handshake_req {
> + void (*th_consumer_done)(void *data, int status,
> + key_serial_t peerid);
> + void *th_consumer_data;
> +
> + int th_type;
> + unsigned int th_timeout_ms;
> + int th_auth_mode;
> + key_serial_t th_keyring;
> + key_serial_t th_peerid;
> + key_serial_t th_certificate;
> + key_serial_t th_privkey;
> +};
> +
> +static struct tls_handshake_req *
> +tls_handshake_req_init(struct handshake_req *req,
> + const struct tls_handshake_args *args)
> +{
> + struct tls_handshake_req *treq = handshake_req_private(req);
> +
> + treq->th_timeout_ms = args->ta_timeout_ms;
> + treq->th_consumer_done = args->ta_done;
> + treq->th_consumer_data = args->ta_data;
> + treq->th_keyring = args->ta_keyring;
> + treq->th_peerid = TLS_NO_PEERID;
> + treq->th_certificate = TLS_NO_CERT;
> + treq->th_privkey = TLS_NO_PRIVKEY;
> + return treq;
> +}
> +
> +/**
> + * tls_handshake_destroy - callback to release a handshake request
> + * @req: handshake parameters to release
> + *
> + */
> +static void tls_handshake_destroy(struct handshake_req *req)
> +{
> +}
> +
> +/**
> + * tls_handshake_done - callback to handle a CMD_DONE request
> + * @req: socket on which the handshake was performed
> + * @status: session status code
> + * @tb: other results of session establishment
> + *
> + */
> +static void tls_handshake_done(struct handshake_req *req,
> + unsigned int status, struct nlattr **tb)
> +{
> + struct tls_handshake_req *treq = handshake_req_private(req);
> + key_serial_t peerid = TLS_NO_PEERID;
> +
> + if (tb && tb[HANDSHAKE_A_DONE_REMOTE_AUTH])
> + peerid = nla_get_u32(tb[HANDSHAKE_A_DONE_REMOTE_AUTH]);
> +
> + treq->th_consumer_done(treq->th_consumer_data, -status, peerid);
> +}
> +
> +#if IS_ENABLED(CONFIG_KEYS)
> +static int tls_handshake_private_keyring(struct tls_handshake_req *treq)
> +{
> + key_ref_t process_keyring_ref, keyring_ref;
> + int ret;
> +
> + if (treq->th_keyring == TLS_NO_KEYRING)
> + return 0;
> +
> + process_keyring_ref = lookup_user_key(KEY_SPEC_PROCESS_KEYRING,
> + KEY_LOOKUP_CREATE,
> + KEY_NEED_WRITE);
> + if (IS_ERR(process_keyring_ref)) {
> + ret = PTR_ERR(process_keyring_ref);
> + goto out;
> + }
> +
> + keyring_ref = lookup_user_key(treq->th_keyring, KEY_LOOKUP_CREATE,
> + KEY_NEED_LINK);
> + if (IS_ERR(keyring_ref)) {
> + ret = PTR_ERR(keyring_ref);
> + goto out_put_key;
> + }
> +
> + ret = key_link(key_ref_to_ptr(process_keyring_ref),
> + key_ref_to_ptr(keyring_ref));
> +
> + key_ref_put(keyring_ref);
> +out_put_key:
> + key_ref_put(process_keyring_ref);
> +out:
> + return ret;
> +}
> +#else
> +static int tls_handshake_private_keyring(struct tls_handshake_req *treq)
> +{
> + return 0;
> +}
> +#endif
> +
> +static int tls_handshake_put_peer_identity(struct sk_buff *msg,
> + struct tls_handshake_req *treq)
> +{
> + if (treq->th_peerid == TLS_NO_PEERID)
> + return 0;
> +
> + if (nla_put_u32(msg, HANDSHAKE_A_ACCEPT_PEER_IDENTITY,
> + treq->th_peerid) < 0)
> + return -EMSGSIZE;
> +
> + return 0;
> +}
> +
> +static int tls_handshake_put_certificate(struct sk_buff *msg,
> + struct tls_handshake_req *treq)
> +{
> + struct nlattr *entry_attr;
> +
> + if (treq->th_certificate == TLS_NO_CERT &&
> + treq->th_privkey == TLS_NO_PRIVKEY)
> + return 0;
> +
> + entry_attr = nla_nest_start(msg, HANDSHAKE_A_ACCEPT_CERTIFICATE);
> + if (!entry_attr)
> + return -EMSGSIZE;
> +
> + if (nla_put_u32(msg, HANDSHAKE_A_X509_CERT,
> + treq->th_certificate) < 0)
> + goto out_cancel;
> + if (nla_put_u32(msg, HANDSHAKE_A_X509_PRIVKEY,
> + treq->th_privkey) < 0)
> + goto out_cancel;
> +
> + nla_nest_end(msg, entry_attr);
> + return 0;
> +
> +out_cancel:
> + nla_nest_cancel(msg, entry_attr);
> + return -EMSGSIZE;
> +}
> +
> +/**
> + * tls_handshake_accept - callback to construct a CMD_ACCEPT response
> + * @req: handshake parameters to return
> + * @gi: generic netlink message context
> + * @fd: file descriptor to be returned
> + *
> + * Returns zero on success, or a negative errno on failure.
> + */
> +static int tls_handshake_accept(struct handshake_req *req,
> + struct genl_info *gi, int fd)
> +{
> + struct tls_handshake_req *treq = handshake_req_private(req);
> + struct nlmsghdr *hdr;
> + struct sk_buff *msg;
> + int ret;
> +
> + ret = tls_handshake_private_keyring(treq);
> + if (ret < 0)
> + goto out;
> +
> + ret = -ENOMEM;
> + msg = genlmsg_new(GENLMSG_DEFAULT_SIZE, GFP_KERNEL);
> + if (!msg)
> + goto out;
> + hdr = handshake_genl_put(msg, gi);
> + if (!hdr)
> + goto out_cancel;
> +
> + ret = -EMSGSIZE;
> + ret = nla_put_u32(msg, HANDSHAKE_A_ACCEPT_SOCKFD, fd);
> + if (ret < 0)
> + goto out_cancel;
> + ret = nla_put_u32(msg, HANDSHAKE_A_ACCEPT_MESSAGE_TYPE, treq->th_type);
> + if (ret < 0)
> + goto out_cancel;
> + if (treq->th_timeout_ms) {
> + ret = nla_put_u32(msg, HANDSHAKE_A_ACCEPT_TIMEOUT, treq->th_timeout_ms);
> + if (ret < 0)
> + goto out_cancel;
> + }
> +
> + ret = nla_put_u32(msg, HANDSHAKE_A_ACCEPT_AUTH_MODE,
> + treq->th_auth_mode);
> + if (ret < 0)
> + goto out_cancel;
> + switch (treq->th_auth_mode) {
> + case HANDSHAKE_AUTH_PSK:
> + ret = tls_handshake_put_peer_identity(msg, treq);
> + if (ret < 0)
> + goto out_cancel;
> + break;
> + case HANDSHAKE_AUTH_X509:
> + ret = tls_handshake_put_certificate(msg, treq);
> + if (ret < 0)
> + goto out_cancel;
> + break;
> + }
> +
> + genlmsg_end(msg, hdr);
> + return genlmsg_reply(msg, gi);
> +
> +out_cancel:
> + genlmsg_cancel(msg, hdr);
> +out:
> + return ret;
> +}
> +
> +static const struct handshake_proto tls_handshake_proto = {
> + .hp_handler_class = HANDSHAKE_HANDLER_CLASS_TLSHD,
> + .hp_privsize = sizeof(struct tls_handshake_req),
> +
> + .hp_accept = tls_handshake_accept,
> + .hp_done = tls_handshake_done,
> + .hp_destroy = tls_handshake_destroy,
> +};
> +
> +/**
> + * tls_client_hello_anon - request an anonymous TLS handshake on a socket
> + * @args: socket and handshake parameters for this request
> + * @flags: memory allocation control flags
> + *
> + * Return values:
> + * %0: Handshake request enqueue; ->done will be called when complete
> + * %-ESRCH: No user agent is available
> + * %-ENOMEM: Memory allocation failed
> + */
> +int tls_client_hello_anon(const struct tls_handshake_args *args, gfp_t flags)
> +{
> + struct tls_handshake_req *treq;
> + struct handshake_req *req;
> +
> + req = handshake_req_alloc(args->ta_sock, &tls_handshake_proto, flags);
> + if (!req)
> + return -ENOMEM;
> + treq = tls_handshake_req_init(req, args);
> + treq->th_type = HANDSHAKE_MSG_TYPE_CLIENTHELLO;
> + treq->th_auth_mode = HANDSHAKE_AUTH_UNAUTH;
> +
> + return handshake_req_submit(req, flags);
> +}
> +EXPORT_SYMBOL(tls_client_hello_anon);
> +
> +/**
> + * tls_client_hello_x509 - request an x.509-based TLS handshake on a socket
> + * @args: socket and handshake parameters for this request
> + * @flags: memory allocation control flags
> + *
> + * Return values:
> + * %0: Handshake request enqueue; ->done will be called when complete
> + * %-ESRCH: No user agent is available
> + * %-ENOMEM: Memory allocation failed
> + */
> +int tls_client_hello_x509(const struct tls_handshake_args *args, gfp_t flags)
> +{
> + struct tls_handshake_req *treq;
> + struct handshake_req *req;
> +
> + req = handshake_req_alloc(args->ta_sock, &tls_handshake_proto, flags);
> + if (!req)
> + return -ENOMEM;
> + treq = tls_handshake_req_init(req, args);
> + treq->th_type = HANDSHAKE_MSG_TYPE_CLIENTHELLO;
> + treq->th_auth_mode = HANDSHAKE_AUTH_X509;
> + treq->th_certificate = args->ta_my_peerid;
> + treq->th_privkey = args->ta_my_privkey;
> +
> + return handshake_req_submit(req, flags);
> +}
> +EXPORT_SYMBOL(tls_client_hello_x509);
> +
> +/**
> + * tls_client_hello_psk - request a PSK-based TLS handshake on a socket
> + * @args: socket and handshake parameters for this request
> + * @flags: memory allocation control flags
> + *
> + * Return values:
> + * %0: Handshake request enqueue; ->done will be called when complete
> + * %-ESRCH: No user agent is available
> + * %-ENOMEM: Memory allocation failed
> + */
> +int tls_client_hello_psk(const struct tls_handshake_args *args, gfp_t flags)
> +{
> + struct tls_handshake_req *treq;
> + struct handshake_req *req;
> +
> + req = handshake_req_alloc(args->ta_sock, &tls_handshake_proto, flags);
> + if (!req)
> + return -ENOMEM;
> + treq = tls_handshake_req_init(req, args);
> + treq->th_type = HANDSHAKE_MSG_TYPE_CLIENTHELLO;
> + treq->th_auth_mode = HANDSHAKE_AUTH_PSK;
> + treq->th_peerid = args->ta_my_peerid;
> +
> + return handshake_req_submit(req, flags);
> +}
> +EXPORT_SYMBOL(tls_client_hello_psk);
> +
> +/**
> + * tls_server_hello_x509 - request a server TLS handshake on a socket
> + * @args: socket and handshake parameters for this request
> + * @flags: memory allocation control flags
> + *
> + * Return values:
> + * %0: Handshake request enqueue; ->done will be called when complete
> + * %-ESRCH: No user agent is available
> + * %-ENOMEM: Memory allocation failed
> + */
> +int tls_server_hello_x509(const struct tls_handshake_args *args, gfp_t flags)
> +{
> + struct tls_handshake_req *treq;
> + struct handshake_req *req;
> +
> + req = handshake_req_alloc(args->ta_sock, &tls_handshake_proto, flags);
> + if (!req)
> + return -ENOMEM;
> + treq = tls_handshake_req_init(req, args);
> + treq->th_type = HANDSHAKE_MSG_TYPE_SERVERHELLO;
> + treq->th_auth_mode = HANDSHAKE_AUTH_X509;
> + treq->th_certificate = args->ta_my_peerid;
> + treq->th_privkey = args->ta_my_privkey;
> +
> + return handshake_req_submit(req, flags);
> +}
> +EXPORT_SYMBOL(tls_server_hello_x509);
> +
> +/**
> + * tls_server_hello_psk - request a server TLS handshake on a socket
> + * @args: socket and handshake parameters for this request
> + * @flags: memory allocation control flags
> + *
> + * Return values:
> + * %0: Handshake request enqueue; ->done will be called when complete
> + * %-ESRCH: No user agent is available
> + * %-ENOMEM: Memory allocation failed
> + */
> +int tls_server_hello_psk(const struct tls_handshake_args *args, gfp_t flags)
> +{
> + struct tls_handshake_req *treq;
> + struct handshake_req *req;
> +
> + req = handshake_req_alloc(args->ta_sock, &tls_handshake_proto, flags);
> + if (!req)
> + return -ENOMEM;
> + treq = tls_handshake_req_init(req, args);
> + treq->th_type = HANDSHAKE_MSG_TYPE_SERVERHELLO;
> + treq->th_auth_mode = HANDSHAKE_AUTH_PSK;
> + treq->th_peerid = args->ta_my_peerid;
> +
> + return handshake_req_submit(req, flags);
> +}
> +EXPORT_SYMBOL(tls_server_hello_psk);
> +
> +/**
> + * tls_handshake_cancel - cancel a pending handshake
> + * @sock: socket on which there is an ongoing handshake
> + *
> + * Request cancellation races with request completion. To determine
> + * who won, callers examine the return value from this function.
> + *
> + * Return values:
> + * %true - Uncompleted handshake request was canceled or not found
> + * %false - Handshake request already completed
> + */
> +bool tls_handshake_cancel(struct socket *sock)
> +{
> + return handshake_req_cancel(sock);
> +}
> +EXPORT_SYMBOL(tls_handshake_cancel);

--
Chuck Lever