Date:   Mon, 27 Feb 2023 15:01:56 +0000
From:   Chuck Lever III <chuck.lever@...cle.com>
To:     Hannes Reinecke <hare@...e.de>
CC:     Chuck Lever <cel@...nel.org>, Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Eric Dumazet <edumazet@...gle.com>,
        "open list:NETWORKING [GENERAL]" <netdev@...r.kernel.org>,
        "kernel-tls-handshake@...ts.linux.dev" 
        <kernel-tls-handshake@...ts.linux.dev>
Subject: Re: [PATCH v5 2/2] net/tls: Add kernel APIs for requesting a TLSv1.3
 handshake



> On Feb 27, 2023, at 4:36 AM, Hannes Reinecke <hare@...e.de> wrote:
> 
> On 2/24/23 20:19, Chuck Lever wrote:
>> From: Chuck Lever <chuck.lever@...cle.com>
>> To enable kernel consumers of TLS to request a TLS handshake, add
>> support to net/tls/ to send a handshake upcall. This patch also
>> acts as a template for adding handshake upcall support to other
>> transport layer security mechanisms.
>> Signed-off-by: Chuck Lever <chuck.lever@...cle.com>
>> ---
>>  Documentation/netlink/specs/handshake.yaml |    4
>>  Documentation/networking/index.rst         |    1
>>  Documentation/networking/tls-handshake.rst |  146 ++++++++++
>>  include/net/tls.h                          |   27 ++
>>  include/uapi/linux/handshake.h             |    2
>>  net/handshake/netlink.c                    |    1
>>  net/tls/Makefile                           |    2
>>  net/tls/tls_handshake.c                    |  423 ++++++++++++++++++++++++++++
>>  8 files changed, 604 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 683a8f2df0a7..c2f6bfff2326 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
>> @@ -132,3 +132,5 @@ 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..f09fc6c09580
>> --- /dev/null
>> +++ b/Documentation/networking/tls-handshake.rst
>> @@ -0,0 +1,146 @@
>> +.. 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. Thus, with the current implementation, a user agent is
>> +started in each network namespace where a kernel consumer might require
>> +a TLS handshake. This agent listens for events sent from the kernel
>> +that request a handshake on an open and connected TCP socket.
>> +
>> +The open socket is passed to user space via a netlink operation, which
>> +creates a socket descriptor in the agent's file descriptor table. If the
>> +handshake completes successfully, the user agent promotes the socket to
>> +use the TLS ULP and sets the session information using the SOL_TLS socket
>> +options. The user 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. For example:
>> +
>> +.. code-block:: c
>> +
>> +  ret = tls_client_hello_x509(sock, done_func, cookie, priorities,
>> +                              cert, privkey);
>> +
>> +The function returns zero when the handshake request is under way. A
>> +zero return guarantees the callback function @done_func 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 @done_func
>> +will not be invoked on this socket.
>> +
>> +The @sock argument is an open and connected socket. The caller must hold
>> +a reference on the socket to prevent it from being destroyed while the
>> +handshake is in progress.
>> +
>> +@...e_func and @cookie are a callback function that is invoked when the
>> +handshake has completed. The success status of the handshake is returned
>> +via the @status parameter of the callback function. A good practice is
>> +to close and destroy the socket immediately if the handshake has failed.
>> +
>> +@...orities is a GnuTLS priorities string that controls the handshake.
>> +The special value TLS_DEFAULT_PRIORITIES causes the handshake to
>> +operate using default TLS priorities. However, the caller can use the
>> +string to (for example) adjust the handshake to use a restricted set
>> +of ciphers (say, if the kernel consumer wishes to mandate only a
>> +limited set of ciphers).
>> +
>> +@...t is the serial number of a key that contains a DER format x.509
>> +certificate that the handshake agent presents to the remote as the local
>> +peer's identity.
>> +
>> +@...vkey is the serial number of a key that contains a DER-format
>> +private key associated with the x.509 certificate.
>> +
>> +
>> +To initiate a client-side TLS handshake with a pre-shared key, use:
>> +
>> +.. code-block:: c
>> +
>> +  ret = tls_client_hello_psk(sock, done_func, cookie, priorities,
>> +                             peerid);
>> +
>> +@...rid is the serial number of a key that contains the pre-shared
>> +key to be used for the handshake.
>> +
>> +The other parameters are as above.
>> +
>> +
>> +To initiate an anonymous client-side TLS handshake use:
>> +
>> +.. code-block:: c
>> +
>> +  ret = tls_client_hello_anon(sock, done_func, cookie, priorities);
>> +
>> +The parameters are as above.
>> +
>> +The handshake agent presents no peer identity information to the
>> +remote during the handshake. Only server authentication 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(sock, done_func, cookie, priorities);
>> +
>> +The parameters for this operation are as above.
>> +
>> +
>> +Lastly, if the consumer needs to cancel the handshake request, say,
>> +due to a ^C or other exigent event, the handshake core provides
>> +this API:
>> +
>> +.. code-block:: c
>> +
>> +  handshake_cancel(sock);
>> +
>> +
>> +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..505b23992ef0 100644
>> --- a/include/net/tls.h
>> +++ b/include/net/tls.h
>> @@ -512,4 +512,31 @@ static inline bool tls_is_sk_rx_device_offloaded(struct sock *sk)
>>  	return tls_get_ctx(sk)->rx_conf == TLS_HW;
>>  }
>>  #endif
>> +
>> +#define TLS_DEFAULT_PRIORITIES		(NULL)
>> +
> 
> Hmm? What is the point in this?
> It's not that we can overwrite it later on ...
> 
>> +enum {
>> +	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);
>> +
>> +int tls_client_hello_anon(struct socket *sock, tls_done_func_t done,
>> +			  void *data, const char *priorities);
>> +int tls_client_hello_x509(struct socket *sock, tls_done_func_t done,
>> +			  void *data, const char *priorities,
>> +			  key_serial_t cert, key_serial_t privkey);
>> +int tls_client_hello_psk(struct socket *sock, tls_done_func_t done,
>> +			 void *data, const char *priorities,
>> +			 key_serial_t peerid);
>> +int tls_server_hello_x509(struct socket *sock, tls_done_func_t done,
>> +			  void *data, const char *priorities);
>> +int tls_server_hello_psk(struct socket *sock, tls_done_func_t done,
>> +			 void *data, const char *priorities);
>> +
>> +int tls_handshake_cancel(struct socket *sock);
>> +
>>  #endif /* _TLS_OFFLOAD_H */
>> diff --git a/include/uapi/linux/handshake.h b/include/uapi/linux/handshake.h
>> index 09fd7c37cba4..dad8227939a1 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 {
>> @@ -59,5 +60,6 @@ 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 581e382236cf..88775f784305 100644
>> --- a/net/handshake/netlink.c
>> +++ b/net/handshake/netlink.c
>> @@ -255,6 +255,7 @@ 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
>>  
> I'd rather tack the new file at the end, but that might be personal preference ...
> 
>>  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..74d32a9ca857
>> --- /dev/null
>> +++ b/net/tls/tls_handshake.c
>> @@ -0,0 +1,423 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/*
>> + * Establish a TLS session for a kernel socket consumer
>> + *
>> + * Author: Chuck Lever <chuck.lever@...cle.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 <net/sock.h>
>> +#include <net/tls.h>
>> +#include <net/genetlink.h>
>> +#include <net/handshake.h>
>> +
>> +#include <uapi/linux/handshake.h>
>> +
>> +/*
>> + * TLS priorities string passed to the GnuTLS library.
>> + *
>> + * Specifically for kernel TLS consumers: enable only TLS v1.3 and the
>> + * ciphers that are supported by kTLS.
>> + *
>> + * Currently this list is generated by hand from the supported ciphers
>> + * found in include/uapi/linux/tls.h.
>> + */
>> +#define KTLS_DEFAULT_PRIORITIES \
>> +	"SECURE256:+SECURE128:-COMP-ALL" \
>> +	":-VERS-ALL:+VERS-TLS1.3:%NO_TICKETS" \
>> +	":-CIPHER-ALL:+CHACHA20-POLY1305:+AES-256-GCM:+AES-128-GCM:+AES-128-CCM"
>> +
>> +struct tls_handshake_req {
>> +	void			(*th_consumer_done)(void *data, int status,
>> +						    key_serial_t peerid);
>> +	void			*th_consumer_data;
>> +
>> +	const char		*th_priorities;
>> +	int			th_type;
>> +	int			th_auth_type;
>> +	key_serial_t		th_peerid;
>> +	key_serial_t		th_certificate;
>> +	key_serial_t		th_privkey;
>> +
>> +};
>> +
>> +static const char *tls_handshake_dup_priorities(const char *priorities,
>> +						gfp_t flags)
>> +{
>> +	const char *tp;
>> +
>> +	if (priorities != TLS_DEFAULT_PRIORITIES && strlen(priorities))
> See above. At TLS_DEFAULT_PRIORITIES is NULL we can leave out the first condition.

strlen() crashes if it's passed a NULL pointer.

What I'm thinking of instead is to simply remove the "priorities" argument
from tls_{client,server}_hello, and leave it as something that is between
net/tls/tls_handshake.c and tlshd.


>> +		tp = priorities;
>> +	else
>> +		tp = KTLS_DEFAULT_PRIORITIES;
>> +	return kstrdup(tp, flags);
>> +}
>> +
>> +static struct tls_handshake_req *
>> +tls_handshake_req_init(struct handshake_req *req, tls_done_func_t done,
>> +		       void *data, const char *priorities)
>> +{
>> +	struct tls_handshake_req *treq = handshake_req_private(req);
>> +
>> +	treq->th_consumer_done = done;
>> +	treq->th_consumer_data = data;
>> +	treq->th_priorities = priorities;
>> +	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)
>> +{
>> +	struct tls_handshake_req *treq = handshake_req_private(req);
>> +
>> +	kfree(treq->th_priorities);
>> +}
>> +
>> +/**
>> + * 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
>> + *
>> + * Eventually this will return information about the established
>> + * session: whether it is authenticated, and if so, who the remote
>> + * is.
>> + */
>> +static void tls_handshake_done(struct handshake_req *req, int status,
>> +			       struct nlattr **tb)
>> +{
>> +	struct tls_handshake_req *treq = handshake_req_private(req);
>> +	key_serial_t peerid = TLS_NO_PEERID;
>> +
>> +	if (tb[HANDSHAKE_A_DONE_REMOTE_PEERID])
>> +		peerid = nla_get_u32(tb[HANDSHAKE_A_DONE_REMOTE_PEERID]);
>> +
>> +	treq->th_consumer_done(treq->th_consumer_data, status, peerid);
>> +}
>> +
>> +static int tls_handshake_put_accept_resp(struct sk_buff *msg,
>> +					 struct tls_handshake_req *treq)
>> +{
>> +	int ret;
>> +
>> +	ret = nla_put_u32(msg, HANDSHAKE_A_ACCEPT_MESSAGE_TYPE, treq->th_type);
>> +	if (ret < 0)
>> +		goto out;
>> +	ret = nla_put_u32(msg, HANDSHAKE_A_ACCEPT_AUTH, treq->th_auth_type);
>> +	if (ret < 0)
>> +		goto out;
>> +	switch (treq->th_auth_type) {
>> +	case HANDSHAKE_AUTH_X509:
>> +		if (treq->th_certificate != TLS_NO_CERT) {
>> +			ret = nla_put_u32(msg, HANDSHAKE_A_ACCEPT_MY_PEERID,
>> +					  treq->th_certificate);
>> +			if (ret < 0)
>> +				goto out;
>> +		}
>> +		if (treq->th_privkey != TLS_NO_PRIVKEY) {
>> +			ret = nla_put_u32(msg, HANDSHAKE_A_ACCEPT_MY_PRIVKEY,
>> +					  treq->th_privkey);
>> +			if (ret < 0)
>> +				goto out;
>> +		}
>> +		break;
>> +	case HANDSHAKE_AUTH_PSK:
>> +		if (treq->th_peerid != TLS_NO_PEERID) {
>> +			ret = nla_put_u32(msg, HANDSHAKE_A_ACCEPT_MY_PEERID,
>> +					  treq->th_peerid);
>> +			if (ret < 0)
>> +				goto out;
>> +		}
>> +		break;
>> +	}
>> +
>> +	ret = nla_put_string(msg, HANDSHAKE_A_ACCEPT_GNUTLS_PRIORITIES,
>> +			     treq->th_priorities);
>> +	if (ret < 0)
>> +		goto out;
>> +
>> +	ret = 0;
>> +
>> +out:
>> +	return ret;
>> +}
>> +
>> +/**
>> + * 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 = -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 = tls_handshake_put_accept_resp(msg, treq);
>> +	if (ret < 0)
>> +		goto out_cancel;
>> +
>> +	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
>> + * @sock: connected socket on which to perform the handshake
>> + * @done: function to call when the handshake has completed
>> + * @data: token to pass back to @done
>> + * @priorities: GnuTLS TLS priorities string, or NULL
>> + *
>> + * Return values:
>> + *   %0: Handshake request enqueue; ->done will be called when complete
>> + *   %-ENOENT: No user agent is available
>> + *   %-ENOMEM: Memory allocation failed
>> + */
>> +int tls_client_hello_anon(struct socket *sock, tls_done_func_t done,
>> +			  void *data, const char *priorities)
>> +{
>> +	struct tls_handshake_req *treq;
>> +	struct handshake_req *req;
>> +	gfp_t flags = GFP_NOWAIT;
>> +	const char *tp;
>> +
>> +	tp = tls_handshake_dup_priorities(priorities, flags);
>> +	if (!tp)
>> +		return -ENOMEM;
>> +
>> +	req = handshake_req_alloc(sock, &tls_handshake_proto, flags);
>> +	if (!req) {
>> +		kfree(tp);
>> +		return -ENOMEM;
>> +	}
>> +
>> +	treq = tls_handshake_req_init(req, done, data, tp);
>> +	treq->th_type = HANDSHAKE_MSG_TYPE_CLIENTHELLO;
>> +	treq->th_auth_type = 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
>> + * @sock: connected socket on which to perform the handshake
>> + * @done: function to call when the handshake has completed
>> + * @data: token to pass back to @done
>> + * @priorities: GnuTLS TLS priorities string
>> + * @cert: serial number of key containing client's x.509 certificate
>> + * @privkey: serial number of key containing client's private key
>> + *
>> + * Return values:
>> + *   %0: Handshake request enqueue; ->done will be called when complete
>> + *   %-ENOENT: No user agent is available
>> + *   %-ENOMEM: Memory allocation failed
>> + */
>> +int tls_client_hello_x509(struct socket *sock, tls_done_func_t done,
>> +			  void *data, const char *priorities,
>> +			  key_serial_t cert, key_serial_t privkey)
>> +{
>> +	struct tls_handshake_req *treq;
>> +	struct handshake_req *req;
>> +	gfp_t flags = GFP_NOWAIT;
>> +	const char *tp;
>> +
>> +	tp = tls_handshake_dup_priorities(priorities, flags);
>> +	if (!tp)
>> +		return -ENOMEM;
>> +
>> +	req = handshake_req_alloc(sock, &tls_handshake_proto, flags);
>> +	if (!req) {
>> +		kfree(tp);
>> +		return -ENOMEM;
>> +	}
>> +
>> +	treq = tls_handshake_req_init(req, done, data, tp);
>> +	treq->th_type = HANDSHAKE_MSG_TYPE_CLIENTHELLO;
>> +	treq->th_auth_type = HANDSHAKE_AUTH_X509;
>> +	treq->th_certificate = cert;
>> +	treq->th_privkey = 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
>> + * @sock: connected socket on which to perform the handshake
>> + * @done: function to call when the handshake has completed
>> + * @data: token to pass back to @done
>> + * @priorities: GnuTLS TLS priorities string
>> + * @peerid: serial number of key containing TLS identity
>> + *
>> + * Return values:
>> + *   %0: Handshake request enqueue; ->done will be called when complete
>> + *   %-ENOENT: No user agent is available
>> + *   %-ENOMEM: Memory allocation failed
>> + */
>> +int tls_client_hello_psk(struct socket *sock, tls_done_func_t done,
>> +			 void *data, const char *priorities,
>> +			 key_serial_t peerid)
>> +{
>> +	struct tls_handshake_req *treq;
>> +	struct handshake_req *req;
>> +	gfp_t flags = GFP_NOWAIT;
>> +	const char *tp;
>> +
>> +	tp = tls_handshake_dup_priorities(priorities, flags);
>> +	if (!tp)
>> +		return -ENOMEM;
>> +
>> +	req = handshake_req_alloc(sock, &tls_handshake_proto, flags);
>> +	if (!req) {
>> +		kfree(tp);
>> +		return -ENOMEM;
>> +	}
>> +
>> +	treq = tls_handshake_req_init(req, done, data, tp);
>> +	treq->th_type = HANDSHAKE_MSG_TYPE_CLIENTHELLO;
>> +	treq->th_auth_type = HANDSHAKE_AUTH_PSK;
>> +	treq->th_peerid = 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
>> + * @sock: connected socket on which to perform the handshake
>> + * @done: function to call when the handshake has completed
>> + * @data: token to pass back to @done
>> + * @priorities: GnuTLS TLS priorities string
>> + *
>> + * Return values:
>> + *   %0: Handshake request enqueue; ->done will be called when complete
>> + *   %-ENOENT: No user agent is available
>> + *   %-ENOMEM: Memory allocation failed
>> + */
>> +int tls_server_hello_x509(struct socket *sock, tls_done_func_t done,
>> +			  void *data, const char *priorities)
>> +{
>> +	struct tls_handshake_req *treq;
>> +	struct handshake_req *req;
>> +	gfp_t flags = GFP_KERNEL;
>> +	const char *tp;
>> +
>> +	tp = tls_handshake_dup_priorities(priorities, flags);
>> +	if (!tp)
>> +		return -ENOMEM;
>> +
>> +	req = handshake_req_alloc(sock, &tls_handshake_proto, flags);
>> +	if (!req) {
>> +		kfree(tp);
>> +		return -ENOMEM;
>> +	}
>> +
>> +	treq = tls_handshake_req_init(req, done, data, tp);
>> +	treq->th_type = HANDSHAKE_MSG_TYPE_SERVERHELLO;
>> +	treq->th_auth_type = HANDSHAKE_AUTH_X509;
>> +
>> +	return handshake_req_submit(req, flags);
>> +}
>> +EXPORT_SYMBOL(tls_server_hello_x509);
>> +
>> +/**
>> + * tls_server_hello_psk - request a server TLS handshake on a socket
>> + * @sock: connected socket on which to perform the handshake
>> + * @done: function to call when the handshake has completed
>> + * @data: token to pass back to @done
>> + * @priorities: GnuTLS TLS priorities string
>> + *
>> + * Return values:
>> + *   %0: Handshake request enqueue; ->done will be called when complete
>> + *   %-ENOENT: No user agent is available
>> + *   %-ENOMEM: Memory allocation failed
>> + */
>> +int tls_server_hello_psk(struct socket *sock, tls_done_func_t done,
>> +			 void *data, const char *priorities)
>> +{
>> +	struct tls_handshake_req *treq;
>> +	struct handshake_req *req;
>> +	gfp_t flags = GFP_KERNEL;
>> +	const char *tp;
>> +
>> +	tp = tls_handshake_dup_priorities(priorities, flags);
>> +	if (!tp)
>> +		return -ENOMEM;
>> +
>> +	req = handshake_req_alloc(sock, &tls_handshake_proto, flags);
>> +	if (!req) {
>> +		kfree(tp);
>> +		return -ENOMEM;
>> +	}
>> +
>> +	treq = tls_handshake_req_init(req, done, data, tp);
>> +	treq->th_type = HANDSHAKE_MSG_TYPE_SERVERHELLO;
>> +	treq->th_auth_type = HANDSHAKE_AUTH_PSK;
>> +
>> +	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:
>> + *   %0 - Uncompleted handshake request was canceled
>> + *   %-EBUSY - Handshake request already completed
>> + */
>> +int tls_handshake_cancel(struct socket *sock)
>> +{
>> +	return handshake_req_cancel(sock);
>> +}
>> +EXPORT_SYMBOL(tls_handshake_cancel);
> 
> Cheers,
> 
> Hannes
> 
> 

--
Chuck Lever

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