Commit e754eba6 authored by David Howells's avatar David Howells
Browse files

rxrpc: Provide a cmsg to specify the amount of Tx data for a call 



Provide a control message that can be specified on the first sendmsg() of a
client call or the first sendmsg() of a service response to indicate the
total length of the data to be transmitted for that call.

Currently, because the length of the payload of an encrypted DATA packet is
encrypted in front of the data, the packet cannot be encrypted until we
know how much data it will hold.

By specifying the length at the beginning of the transmit phase, each DATA
packet length can be set before we start loading data from userspace (where
several sendmsg() calls may contribute to a particular packet).

An error will be returned if too little or too much data is presented in
the Tx phase.

Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
parent 3ab26a6f

Documentation/networking/rxrpc.txt

+34 −0
Original line number Diff line number Diff line
@@ -327,6 +327,7 @@ calls, to invoke certain actions and to report certain conditions. These are: 
	RXRPC_ACCEPT		s-- n/a		Accept new call

	RXRPC_EXCLUSIVE_CALL	s-- n/a		Make an exclusive client call

	RXRPC_UPGRADE_SERVICE	s-- n/a		Client call can be upgraded

	RXRPC_TX_LENGTH		s-- data len	Total length of Tx data



	(SRT = usable in Sendmsg / delivered by Recvmsg / Terminal message)
@@ -406,6 +407,19 @@ calls, to invoke certain actions and to report certain conditions. These are: 
     future communication to that server and RXRPC_UPGRADE_SERVICE should no

     longer be set.



 (*) RXRPC_TX_LENGTH



     This is used to inform the kernel of the total amount of data that is

     going to be transmitted by a call (whether in a client request or a

     service response).  If given, it allows the kernel to encrypt from the

     userspace buffer directly to the packet buffers, rather than copying into

     the buffer and then encrypting in place.  This may only be given with the

     first sendmsg() providing data for a call.  EMSGSIZE will be generated if

     the amount of data actually given is different.



     This takes a parameter of __s64 type that indicates how much will be

     transmitted.  This may not be less than zero.



The symbol RXRPC__SUPPORTED is defined as one more than the highest control

message type supported.  At run time this can be queried by means of the

RXRPC_SUPPORTED_CMSG socket option (see below).
@@ -577,6 +591,9 @@ A client would issue an operation by: 
     MSG_MORE should be set in msghdr::msg_flags on all but the last part of

     the request.  Multiple requests may be made simultaneously.



     An RXRPC_TX_LENGTH control message can also be specified on the first

     sendmsg() call.



     If a call is intended to go to a destination other than the default

     specified through connect(), then msghdr::msg_name should be set on the

     first request message of that call.
@@ -764,6 +781,7 @@ The kernel interface functions are as follows: 
				struct sockaddr_rxrpc *srx,

				struct key *key,

				unsigned long user_call_ID,

				s64 tx_total_len,

				gfp_t gfp);



     This allocates the infrastructure to make a new RxRPC call and assigns
@@ -780,6 +798,11 @@ The kernel interface functions are as follows: 
     control data buffer.  It is entirely feasible to use this to point to a

     kernel data structure.



     tx_total_len is the amount of data the caller is intending to transmit

     with this call (or -1 if unknown at this point).  Setting the data size

     allows the kernel to encrypt directly to the packet buffers, thereby

     saving a copy.  The value may not be less than -1.



     If this function is successful, an opaque reference to the RxRPC call is

     returned.  The caller now holds a reference on this and it must be

     properly ended.
@@ -931,6 +954,17 @@ The kernel interface functions are as follows: 


     This is used to find the remote peer address of a call.



 (*) Set the total transmit data size on a call.



	void rxrpc_kernel_set_tx_length(struct socket *sock,

					struct rxrpc_call *call,

					s64 tx_total_len);



     This sets the amount of data that the caller is intending to transmit on a

     call.  It's intended to be used for setting the reply size as the request

     size should be set when the call is begun.  tx_total_len may not be less

     than zero.





=======================

CONFIGURABLE PARAMETERS

fs/afs/rxrpc.c

+17 −1
Original line number Diff line number Diff line
@@ -341,6 +341,7 @@ int afs_make_call(struct in_addr *addr, struct afs_call *call, gfp_t gfp, 
	struct msghdr msg;

	struct kvec iov[1];

	size_t offset;

	s64 tx_total_len;

	u32 abort_code;

	int ret;
@@ -364,9 +365,20 @@ int afs_make_call(struct in_addr *addr, struct afs_call *call, gfp_t gfp, 
	srx.transport.sin.sin_port = call->port;

	memcpy(&srx.transport.sin.sin_addr, addr, 4);



	/* Work out the length we're going to transmit.  This is awkward for

	 * calls such as FS.StoreData where there's an extra injection of data

	 * after the initial fixed part.

	 */

	tx_total_len = call->request_size;

	if (call->send_pages) {

		tx_total_len += call->last_to - call->first_offset;

		tx_total_len += (call->last - call->first) * PAGE_SIZE;

	}



	/* create a call */

	rxcall = rxrpc_kernel_begin_call(afs_socket, &srx, call->key,

					 (unsigned long) call, gfp,

					 (unsigned long)call,

					 tx_total_len, gfp,

					 (async ?

					  afs_wake_up_async_call :

					  afs_wake_up_call_waiter));
@@ -738,6 +750,8 @@ void afs_send_empty_reply(struct afs_call *call) 


	_enter("");



	rxrpc_kernel_set_tx_length(afs_socket, call->rxcall, 0);



	msg.msg_name		= NULL;

	msg.msg_namelen		= 0;

	iov_iter_kvec(&msg.msg_iter, WRITE | ITER_KVEC, NULL, 0, 0);
@@ -772,6 +786,8 @@ void afs_send_simple_reply(struct afs_call *call, const void *buf, size_t len) 


	_enter("");



	rxrpc_kernel_set_tx_length(afs_socket, call->rxcall, len);



	iov[0].iov_base		= (void *) buf;

	iov[0].iov_len		= len;

	msg.msg_name		= NULL;

include/linux/rxrpc.h

+1 −0
Original line number Diff line number Diff line
@@ -57,6 +57,7 @@ enum rxrpc_cmsg_type { 
	RXRPC_ACCEPT		= 9,	/* s-: [Service] accept request */

	RXRPC_EXCLUSIVE_CALL	= 10,	/* s-: Call should be on exclusive connection */

	RXRPC_UPGRADE_SERVICE	= 11,	/* s-: Request service upgrade for client call */

	RXRPC_TX_LENGTH		= 12,	/* s-: Total length of Tx data */

	RXRPC__SUPPORTED

};

include/net/af_rxrpc.h

+2 −0
Original line number Diff line number Diff line
@@ -33,6 +33,7 @@ struct rxrpc_call *rxrpc_kernel_begin_call(struct socket *, 
					   struct sockaddr_rxrpc *,

					   struct key *,

					   unsigned long,

					   s64,

					   gfp_t,

					   rxrpc_notify_rx_t);

int rxrpc_kernel_send_data(struct socket *, struct rxrpc_call *,
@@ -46,5 +47,6 @@ void rxrpc_kernel_get_peer(struct socket *, struct rxrpc_call *, 
			   struct sockaddr_rxrpc *);

int rxrpc_kernel_charge_accept(struct socket *, rxrpc_notify_rx_t,

			       rxrpc_user_attach_call_t, unsigned long, gfp_t);

void rxrpc_kernel_set_tx_length(struct socket *, struct rxrpc_call *, s64);



#endif /* _NET_RXRPC_H */

net/rxrpc/af_rxrpc.c

+4 −1
Original line number Diff line number Diff line
@@ -262,6 +262,7 @@ static int rxrpc_listen(struct socket *sock, int backlog) 
 * @srx: The address of the peer to contact

 * @key: The security context to use (defaults to socket setting)

 * @user_call_ID: The ID to use

 * @tx_total_len: Total length of data to transmit during the call (or -1)

 * @gfp: The allocation constraints

 * @notify_rx: Where to send notifications instead of socket queue

 *
@@ -276,6 +277,7 @@ struct rxrpc_call *rxrpc_kernel_begin_call(struct socket *sock, 
					   struct sockaddr_rxrpc *srx,

					   struct key *key,

					   unsigned long user_call_ID,

					   s64 tx_total_len,

					   gfp_t gfp,

					   rxrpc_notify_rx_t notify_rx)

{
@@ -303,7 +305,8 @@ struct rxrpc_call *rxrpc_kernel_begin_call(struct socket *sock, 
	cp.security_level	= 0;

	cp.exclusive		= false;

	cp.service_id		= srx->srx_service;

	call = rxrpc_new_client_call(rx, &cp, srx, user_call_ID, gfp);

	call = rxrpc_new_client_call(rx, &cp, srx, user_call_ID, tx_total_len,

				     gfp);

	/* The socket has been unlocked. */

	if (!IS_ERR(call))

		call->notify_rx = notify_rx;

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