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1 /* RxRPC packet transmission
2  *
3  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
4  * Written by David Howells (dhowells@redhat.com)
5  *
6  * This program is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU General Public License
8  * as published by the Free Software Foundation; either version
9  * 2 of the License, or (at your option) any later version.
10  */
11 
12 #include <linux/net.h>
13 #include <linux/gfp.h>
14 #include <linux/skbuff.h>
15 #include <linux/circ_buf.h>
16 #include <linux/export.h>
17 #include <net/sock.h>
18 #include <net/af_rxrpc.h>
19 #include "ar-internal.h"
20 
21 /*
22  * Time till packet resend (in jiffies).
23  */
24 unsigned rxrpc_resend_timeout = 4 * HZ;
25 
26 static int rxrpc_send_data(struct kiocb *iocb,
27 			   struct rxrpc_sock *rx,
28 			   struct rxrpc_call *call,
29 			   struct msghdr *msg, size_t len);
30 
31 /*
32  * extract control messages from the sendmsg() control buffer
33  */
rxrpc_sendmsg_cmsg(struct rxrpc_sock * rx,struct msghdr * msg,unsigned long * user_call_ID,enum rxrpc_command * command,u32 * abort_code,bool server)34 static int rxrpc_sendmsg_cmsg(struct rxrpc_sock *rx, struct msghdr *msg,
35 			      unsigned long *user_call_ID,
36 			      enum rxrpc_command *command,
37 			      u32 *abort_code,
38 			      bool server)
39 {
40 	struct cmsghdr *cmsg;
41 	int len;
42 
43 	*command = RXRPC_CMD_SEND_DATA;
44 
45 	if (msg->msg_controllen == 0)
46 		return -EINVAL;
47 
48 	for (cmsg = CMSG_FIRSTHDR(msg); cmsg; cmsg = CMSG_NXTHDR(msg, cmsg)) {
49 		if (!CMSG_OK(msg, cmsg))
50 			return -EINVAL;
51 
52 		len = cmsg->cmsg_len - CMSG_ALIGN(sizeof(struct cmsghdr));
53 		_debug("CMSG %d, %d, %d",
54 		       cmsg->cmsg_level, cmsg->cmsg_type, len);
55 
56 		if (cmsg->cmsg_level != SOL_RXRPC)
57 			continue;
58 
59 		switch (cmsg->cmsg_type) {
60 		case RXRPC_USER_CALL_ID:
61 			if (msg->msg_flags & MSG_CMSG_COMPAT) {
62 				if (len != sizeof(u32))
63 					return -EINVAL;
64 				*user_call_ID = *(u32 *) CMSG_DATA(cmsg);
65 			} else {
66 				if (len != sizeof(unsigned long))
67 					return -EINVAL;
68 				*user_call_ID = *(unsigned long *)
69 					CMSG_DATA(cmsg);
70 			}
71 			_debug("User Call ID %lx", *user_call_ID);
72 			break;
73 
74 		case RXRPC_ABORT:
75 			if (*command != RXRPC_CMD_SEND_DATA)
76 				return -EINVAL;
77 			*command = RXRPC_CMD_SEND_ABORT;
78 			if (len != sizeof(*abort_code))
79 				return -EINVAL;
80 			*abort_code = *(unsigned int *) CMSG_DATA(cmsg);
81 			_debug("Abort %x", *abort_code);
82 			if (*abort_code == 0)
83 				return -EINVAL;
84 			break;
85 
86 		case RXRPC_ACCEPT:
87 			if (*command != RXRPC_CMD_SEND_DATA)
88 				return -EINVAL;
89 			*command = RXRPC_CMD_ACCEPT;
90 			if (len != 0)
91 				return -EINVAL;
92 			if (!server)
93 				return -EISCONN;
94 			break;
95 
96 		default:
97 			return -EINVAL;
98 		}
99 	}
100 
101 	_leave(" = 0");
102 	return 0;
103 }
104 
105 /*
106  * abort a call, sending an ABORT packet to the peer
107  */
rxrpc_send_abort(struct rxrpc_call * call,u32 abort_code)108 static void rxrpc_send_abort(struct rxrpc_call *call, u32 abort_code)
109 {
110 	write_lock_bh(&call->state_lock);
111 
112 	if (call->state <= RXRPC_CALL_COMPLETE) {
113 		call->state = RXRPC_CALL_LOCALLY_ABORTED;
114 		call->abort_code = abort_code;
115 		set_bit(RXRPC_CALL_ABORT, &call->events);
116 		del_timer_sync(&call->resend_timer);
117 		del_timer_sync(&call->ack_timer);
118 		clear_bit(RXRPC_CALL_RESEND_TIMER, &call->events);
119 		clear_bit(RXRPC_CALL_ACK, &call->events);
120 		clear_bit(RXRPC_CALL_RUN_RTIMER, &call->flags);
121 		rxrpc_queue_call(call);
122 	}
123 
124 	write_unlock_bh(&call->state_lock);
125 }
126 
127 /*
128  * send a message forming part of a client call through an RxRPC socket
129  * - caller holds the socket locked
130  * - the socket may be either a client socket or a server socket
131  */
rxrpc_client_sendmsg(struct kiocb * iocb,struct rxrpc_sock * rx,struct rxrpc_transport * trans,struct msghdr * msg,size_t len)132 int rxrpc_client_sendmsg(struct kiocb *iocb, struct rxrpc_sock *rx,
133 			 struct rxrpc_transport *trans, struct msghdr *msg,
134 			 size_t len)
135 {
136 	struct rxrpc_conn_bundle *bundle;
137 	enum rxrpc_command cmd;
138 	struct rxrpc_call *call;
139 	unsigned long user_call_ID = 0;
140 	struct key *key;
141 	__be16 service_id;
142 	u32 abort_code = 0;
143 	int ret;
144 
145 	_enter("");
146 
147 	ASSERT(trans != NULL);
148 
149 	ret = rxrpc_sendmsg_cmsg(rx, msg, &user_call_ID, &cmd, &abort_code,
150 				 false);
151 	if (ret < 0)
152 		return ret;
153 
154 	bundle = NULL;
155 	if (trans) {
156 		service_id = rx->service_id;
157 		if (msg->msg_name) {
158 			DECLARE_SOCKADDR(struct sockaddr_rxrpc *, srx,
159 					 msg->msg_name);
160 			service_id = htons(srx->srx_service);
161 		}
162 		key = rx->key;
163 		if (key && !rx->key->payload.data)
164 			key = NULL;
165 		bundle = rxrpc_get_bundle(rx, trans, key, service_id,
166 					  GFP_KERNEL);
167 		if (IS_ERR(bundle))
168 			return PTR_ERR(bundle);
169 	}
170 
171 	call = rxrpc_get_client_call(rx, trans, bundle, user_call_ID,
172 				     abort_code == 0, GFP_KERNEL);
173 	if (trans)
174 		rxrpc_put_bundle(trans, bundle);
175 	if (IS_ERR(call)) {
176 		_leave(" = %ld", PTR_ERR(call));
177 		return PTR_ERR(call);
178 	}
179 
180 	_debug("CALL %d USR %lx ST %d on CONN %p",
181 	       call->debug_id, call->user_call_ID, call->state, call->conn);
182 
183 	if (call->state >= RXRPC_CALL_COMPLETE) {
184 		/* it's too late for this call */
185 		ret = -ESHUTDOWN;
186 	} else if (cmd == RXRPC_CMD_SEND_ABORT) {
187 		rxrpc_send_abort(call, abort_code);
188 	} else if (cmd != RXRPC_CMD_SEND_DATA) {
189 		ret = -EINVAL;
190 	} else if (call->state != RXRPC_CALL_CLIENT_SEND_REQUEST) {
191 		/* request phase complete for this client call */
192 		ret = -EPROTO;
193 	} else {
194 		ret = rxrpc_send_data(iocb, rx, call, msg, len);
195 	}
196 
197 	rxrpc_put_call(call);
198 	_leave(" = %d", ret);
199 	return ret;
200 }
201 
202 /**
203  * rxrpc_kernel_send_data - Allow a kernel service to send data on a call
204  * @call: The call to send data through
205  * @msg: The data to send
206  * @len: The amount of data to send
207  *
208  * Allow a kernel service to send data on a call.  The call must be in an state
209  * appropriate to sending data.  No control data should be supplied in @msg,
210  * nor should an address be supplied.  MSG_MORE should be flagged if there's
211  * more data to come, otherwise this data will end the transmission phase.
212  */
rxrpc_kernel_send_data(struct rxrpc_call * call,struct msghdr * msg,size_t len)213 int rxrpc_kernel_send_data(struct rxrpc_call *call, struct msghdr *msg,
214 			   size_t len)
215 {
216 	int ret;
217 
218 	_enter("{%d,%s},", call->debug_id, rxrpc_call_states[call->state]);
219 
220 	ASSERTCMP(msg->msg_name, ==, NULL);
221 	ASSERTCMP(msg->msg_control, ==, NULL);
222 
223 	lock_sock(&call->socket->sk);
224 
225 	_debug("CALL %d USR %lx ST %d on CONN %p",
226 	       call->debug_id, call->user_call_ID, call->state, call->conn);
227 
228 	if (call->state >= RXRPC_CALL_COMPLETE) {
229 		ret = -ESHUTDOWN; /* it's too late for this call */
230 	} else if (call->state != RXRPC_CALL_CLIENT_SEND_REQUEST &&
231 		   call->state != RXRPC_CALL_SERVER_ACK_REQUEST &&
232 		   call->state != RXRPC_CALL_SERVER_SEND_REPLY) {
233 		ret = -EPROTO; /* request phase complete for this client call */
234 	} else {
235 		mm_segment_t oldfs = get_fs();
236 		set_fs(KERNEL_DS);
237 		ret = rxrpc_send_data(NULL, call->socket, call, msg, len);
238 		set_fs(oldfs);
239 	}
240 
241 	release_sock(&call->socket->sk);
242 	_leave(" = %d", ret);
243 	return ret;
244 }
245 
246 EXPORT_SYMBOL(rxrpc_kernel_send_data);
247 
248 /**
249  * rxrpc_kernel_abort_call - Allow a kernel service to abort a call
250  * @call: The call to be aborted
251  * @abort_code: The abort code to stick into the ABORT packet
252  *
253  * Allow a kernel service to abort a call, if it's still in an abortable state.
254  */
rxrpc_kernel_abort_call(struct rxrpc_call * call,u32 abort_code)255 void rxrpc_kernel_abort_call(struct rxrpc_call *call, u32 abort_code)
256 {
257 	_enter("{%d},%d", call->debug_id, abort_code);
258 
259 	lock_sock(&call->socket->sk);
260 
261 	_debug("CALL %d USR %lx ST %d on CONN %p",
262 	       call->debug_id, call->user_call_ID, call->state, call->conn);
263 
264 	if (call->state < RXRPC_CALL_COMPLETE)
265 		rxrpc_send_abort(call, abort_code);
266 
267 	release_sock(&call->socket->sk);
268 	_leave("");
269 }
270 
271 EXPORT_SYMBOL(rxrpc_kernel_abort_call);
272 
273 /*
274  * send a message through a server socket
275  * - caller holds the socket locked
276  */
rxrpc_server_sendmsg(struct kiocb * iocb,struct rxrpc_sock * rx,struct msghdr * msg,size_t len)277 int rxrpc_server_sendmsg(struct kiocb *iocb, struct rxrpc_sock *rx,
278 			 struct msghdr *msg, size_t len)
279 {
280 	enum rxrpc_command cmd;
281 	struct rxrpc_call *call;
282 	unsigned long user_call_ID = 0;
283 	u32 abort_code = 0;
284 	int ret;
285 
286 	_enter("");
287 
288 	ret = rxrpc_sendmsg_cmsg(rx, msg, &user_call_ID, &cmd, &abort_code,
289 				 true);
290 	if (ret < 0)
291 		return ret;
292 
293 	if (cmd == RXRPC_CMD_ACCEPT) {
294 		call = rxrpc_accept_call(rx, user_call_ID);
295 		if (IS_ERR(call))
296 			return PTR_ERR(call);
297 		rxrpc_put_call(call);
298 		return 0;
299 	}
300 
301 	call = rxrpc_find_server_call(rx, user_call_ID);
302 	if (!call)
303 		return -EBADSLT;
304 	if (call->state >= RXRPC_CALL_COMPLETE) {
305 		ret = -ESHUTDOWN;
306 		goto out;
307 	}
308 
309 	switch (cmd) {
310 	case RXRPC_CMD_SEND_DATA:
311 		if (call->state != RXRPC_CALL_CLIENT_SEND_REQUEST &&
312 		    call->state != RXRPC_CALL_SERVER_ACK_REQUEST &&
313 		    call->state != RXRPC_CALL_SERVER_SEND_REPLY) {
314 			/* Tx phase not yet begun for this call */
315 			ret = -EPROTO;
316 			break;
317 		}
318 
319 		ret = rxrpc_send_data(iocb, rx, call, msg, len);
320 		break;
321 
322 	case RXRPC_CMD_SEND_ABORT:
323 		rxrpc_send_abort(call, abort_code);
324 		break;
325 	default:
326 		BUG();
327 	}
328 
329 	out:
330 	rxrpc_put_call(call);
331 	_leave(" = %d", ret);
332 	return ret;
333 }
334 
335 /*
336  * send a packet through the transport endpoint
337  */
rxrpc_send_packet(struct rxrpc_transport * trans,struct sk_buff * skb)338 int rxrpc_send_packet(struct rxrpc_transport *trans, struct sk_buff *skb)
339 {
340 	struct kvec iov[1];
341 	struct msghdr msg;
342 	int ret, opt;
343 
344 	_enter(",{%d}", skb->len);
345 
346 	iov[0].iov_base = skb->head;
347 	iov[0].iov_len = skb->len;
348 
349 	msg.msg_name = &trans->peer->srx.transport.sin;
350 	msg.msg_namelen = sizeof(trans->peer->srx.transport.sin);
351 	msg.msg_control = NULL;
352 	msg.msg_controllen = 0;
353 	msg.msg_flags = 0;
354 
355 	/* send the packet with the don't fragment bit set if we currently
356 	 * think it's small enough */
357 	if (skb->len - sizeof(struct rxrpc_header) < trans->peer->maxdata) {
358 		down_read(&trans->local->defrag_sem);
359 		/* send the packet by UDP
360 		 * - returns -EMSGSIZE if UDP would have to fragment the packet
361 		 *   to go out of the interface
362 		 *   - in which case, we'll have processed the ICMP error
363 		 *     message and update the peer record
364 		 */
365 		ret = kernel_sendmsg(trans->local->socket, &msg, iov, 1,
366 				     iov[0].iov_len);
367 
368 		up_read(&trans->local->defrag_sem);
369 		if (ret == -EMSGSIZE)
370 			goto send_fragmentable;
371 
372 		_leave(" = %d [%u]", ret, trans->peer->maxdata);
373 		return ret;
374 	}
375 
376 send_fragmentable:
377 	/* attempt to send this message with fragmentation enabled */
378 	_debug("send fragment");
379 
380 	down_write(&trans->local->defrag_sem);
381 	opt = IP_PMTUDISC_DONT;
382 	ret = kernel_setsockopt(trans->local->socket, SOL_IP, IP_MTU_DISCOVER,
383 				(char *) &opt, sizeof(opt));
384 	if (ret == 0) {
385 		ret = kernel_sendmsg(trans->local->socket, &msg, iov, 1,
386 				     iov[0].iov_len);
387 
388 		opt = IP_PMTUDISC_DO;
389 		kernel_setsockopt(trans->local->socket, SOL_IP,
390 				  IP_MTU_DISCOVER, (char *) &opt, sizeof(opt));
391 	}
392 
393 	up_write(&trans->local->defrag_sem);
394 	_leave(" = %d [frag %u]", ret, trans->peer->maxdata);
395 	return ret;
396 }
397 
398 /*
399  * wait for space to appear in the transmit/ACK window
400  * - caller holds the socket locked
401  */
rxrpc_wait_for_tx_window(struct rxrpc_sock * rx,struct rxrpc_call * call,long * timeo)402 static int rxrpc_wait_for_tx_window(struct rxrpc_sock *rx,
403 				    struct rxrpc_call *call,
404 				    long *timeo)
405 {
406 	DECLARE_WAITQUEUE(myself, current);
407 	int ret;
408 
409 	_enter(",{%d},%ld",
410 	       CIRC_SPACE(call->acks_head, call->acks_tail, call->acks_winsz),
411 	       *timeo);
412 
413 	add_wait_queue(&call->tx_waitq, &myself);
414 
415 	for (;;) {
416 		set_current_state(TASK_INTERRUPTIBLE);
417 		ret = 0;
418 		if (CIRC_SPACE(call->acks_head, call->acks_tail,
419 			       call->acks_winsz) > 0)
420 			break;
421 		if (signal_pending(current)) {
422 			ret = sock_intr_errno(*timeo);
423 			break;
424 		}
425 
426 		release_sock(&rx->sk);
427 		*timeo = schedule_timeout(*timeo);
428 		lock_sock(&rx->sk);
429 	}
430 
431 	remove_wait_queue(&call->tx_waitq, &myself);
432 	set_current_state(TASK_RUNNING);
433 	_leave(" = %d", ret);
434 	return ret;
435 }
436 
437 /*
438  * attempt to schedule an instant Tx resend
439  */
rxrpc_instant_resend(struct rxrpc_call * call)440 static inline void rxrpc_instant_resend(struct rxrpc_call *call)
441 {
442 	read_lock_bh(&call->state_lock);
443 	if (try_to_del_timer_sync(&call->resend_timer) >= 0) {
444 		clear_bit(RXRPC_CALL_RUN_RTIMER, &call->flags);
445 		if (call->state < RXRPC_CALL_COMPLETE &&
446 		    !test_and_set_bit(RXRPC_CALL_RESEND_TIMER, &call->events))
447 			rxrpc_queue_call(call);
448 	}
449 	read_unlock_bh(&call->state_lock);
450 }
451 
452 /*
453  * queue a packet for transmission, set the resend timer and attempt
454  * to send the packet immediately
455  */
rxrpc_queue_packet(struct rxrpc_call * call,struct sk_buff * skb,bool last)456 static void rxrpc_queue_packet(struct rxrpc_call *call, struct sk_buff *skb,
457 			       bool last)
458 {
459 	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
460 	int ret;
461 
462 	_net("queue skb %p [%d]", skb, call->acks_head);
463 
464 	ASSERT(call->acks_window != NULL);
465 	call->acks_window[call->acks_head] = (unsigned long) skb;
466 	smp_wmb();
467 	call->acks_head = (call->acks_head + 1) & (call->acks_winsz - 1);
468 
469 	if (last || call->state == RXRPC_CALL_SERVER_ACK_REQUEST) {
470 		_debug("________awaiting reply/ACK__________");
471 		write_lock_bh(&call->state_lock);
472 		switch (call->state) {
473 		case RXRPC_CALL_CLIENT_SEND_REQUEST:
474 			call->state = RXRPC_CALL_CLIENT_AWAIT_REPLY;
475 			break;
476 		case RXRPC_CALL_SERVER_ACK_REQUEST:
477 			call->state = RXRPC_CALL_SERVER_SEND_REPLY;
478 			if (!last)
479 				break;
480 		case RXRPC_CALL_SERVER_SEND_REPLY:
481 			call->state = RXRPC_CALL_SERVER_AWAIT_ACK;
482 			break;
483 		default:
484 			break;
485 		}
486 		write_unlock_bh(&call->state_lock);
487 	}
488 
489 	_proto("Tx DATA %%%u { #%u }",
490 	       ntohl(sp->hdr.serial), ntohl(sp->hdr.seq));
491 
492 	sp->need_resend = false;
493 	sp->resend_at = jiffies + rxrpc_resend_timeout;
494 	if (!test_and_set_bit(RXRPC_CALL_RUN_RTIMER, &call->flags)) {
495 		_debug("run timer");
496 		call->resend_timer.expires = sp->resend_at;
497 		add_timer(&call->resend_timer);
498 	}
499 
500 	/* attempt to cancel the rx-ACK timer, deferring reply transmission if
501 	 * we're ACK'ing the request phase of an incoming call */
502 	ret = -EAGAIN;
503 	if (try_to_del_timer_sync(&call->ack_timer) >= 0) {
504 		/* the packet may be freed by rxrpc_process_call() before this
505 		 * returns */
506 		ret = rxrpc_send_packet(call->conn->trans, skb);
507 		_net("sent skb %p", skb);
508 	} else {
509 		_debug("failed to delete ACK timer");
510 	}
511 
512 	if (ret < 0) {
513 		_debug("need instant resend %d", ret);
514 		sp->need_resend = true;
515 		rxrpc_instant_resend(call);
516 	}
517 
518 	_leave("");
519 }
520 
521 /*
522  * send data through a socket
523  * - must be called in process context
524  * - caller holds the socket locked
525  */
rxrpc_send_data(struct kiocb * iocb,struct rxrpc_sock * rx,struct rxrpc_call * call,struct msghdr * msg,size_t len)526 static int rxrpc_send_data(struct kiocb *iocb,
527 			   struct rxrpc_sock *rx,
528 			   struct rxrpc_call *call,
529 			   struct msghdr *msg, size_t len)
530 {
531 	struct rxrpc_skb_priv *sp;
532 	unsigned char __user *from;
533 	struct sk_buff *skb;
534 	struct iovec *iov;
535 	struct sock *sk = &rx->sk;
536 	long timeo;
537 	bool more;
538 	int ret, ioc, segment, copied;
539 
540 	_enter(",,,{%zu},%zu", msg->msg_iovlen, len);
541 
542 	timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
543 
544 	/* this should be in poll */
545 	clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
546 
547 	if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
548 		return -EPIPE;
549 
550 	iov = msg->msg_iov;
551 	ioc = msg->msg_iovlen - 1;
552 	from = iov->iov_base;
553 	segment = iov->iov_len;
554 	iov++;
555 	more = msg->msg_flags & MSG_MORE;
556 
557 	skb = call->tx_pending;
558 	call->tx_pending = NULL;
559 
560 	copied = 0;
561 	do {
562 		int copy;
563 
564 		if (segment > len)
565 			segment = len;
566 
567 		_debug("SEGMENT %d @%p", segment, from);
568 
569 		if (!skb) {
570 			size_t size, chunk, max, space;
571 
572 			_debug("alloc");
573 
574 			if (CIRC_SPACE(call->acks_head, call->acks_tail,
575 				       call->acks_winsz) <= 0) {
576 				ret = -EAGAIN;
577 				if (msg->msg_flags & MSG_DONTWAIT)
578 					goto maybe_error;
579 				ret = rxrpc_wait_for_tx_window(rx, call,
580 							       &timeo);
581 				if (ret < 0)
582 					goto maybe_error;
583 			}
584 
585 			max = call->conn->trans->peer->maxdata;
586 			max -= call->conn->security_size;
587 			max &= ~(call->conn->size_align - 1UL);
588 
589 			chunk = max;
590 			if (chunk > len && !more)
591 				chunk = len;
592 
593 			space = chunk + call->conn->size_align;
594 			space &= ~(call->conn->size_align - 1UL);
595 
596 			size = space + call->conn->header_size;
597 
598 			_debug("SIZE: %zu/%zu/%zu", chunk, space, size);
599 
600 			/* create a buffer that we can retain until it's ACK'd */
601 			skb = sock_alloc_send_skb(
602 				sk, size, msg->msg_flags & MSG_DONTWAIT, &ret);
603 			if (!skb)
604 				goto maybe_error;
605 
606 			rxrpc_new_skb(skb);
607 
608 			_debug("ALLOC SEND %p", skb);
609 
610 			ASSERTCMP(skb->mark, ==, 0);
611 
612 			_debug("HS: %u", call->conn->header_size);
613 			skb_reserve(skb, call->conn->header_size);
614 			skb->len += call->conn->header_size;
615 
616 			sp = rxrpc_skb(skb);
617 			sp->remain = chunk;
618 			if (sp->remain > skb_tailroom(skb))
619 				sp->remain = skb_tailroom(skb);
620 
621 			_net("skb: hr %d, tr %d, hl %d, rm %d",
622 			       skb_headroom(skb),
623 			       skb_tailroom(skb),
624 			       skb_headlen(skb),
625 			       sp->remain);
626 
627 			skb->ip_summed = CHECKSUM_UNNECESSARY;
628 		}
629 
630 		_debug("append");
631 		sp = rxrpc_skb(skb);
632 
633 		/* append next segment of data to the current buffer */
634 		copy = skb_tailroom(skb);
635 		ASSERTCMP(copy, >, 0);
636 		if (copy > segment)
637 			copy = segment;
638 		if (copy > sp->remain)
639 			copy = sp->remain;
640 
641 		_debug("add");
642 		ret = skb_add_data(skb, from, copy);
643 		_debug("added");
644 		if (ret < 0)
645 			goto efault;
646 		sp->remain -= copy;
647 		skb->mark += copy;
648 		copied += copy;
649 
650 		len -= copy;
651 		segment -= copy;
652 		from += copy;
653 		while (segment == 0 && ioc > 0) {
654 			from = iov->iov_base;
655 			segment = iov->iov_len;
656 			iov++;
657 			ioc--;
658 		}
659 		if (len == 0) {
660 			segment = 0;
661 			ioc = 0;
662 		}
663 
664 		/* check for the far side aborting the call or a network error
665 		 * occurring */
666 		if (call->state > RXRPC_CALL_COMPLETE)
667 			goto call_aborted;
668 
669 		/* add the packet to the send queue if it's now full */
670 		if (sp->remain <= 0 || (segment == 0 && !more)) {
671 			struct rxrpc_connection *conn = call->conn;
672 			uint32_t seq;
673 			size_t pad;
674 
675 			/* pad out if we're using security */
676 			if (conn->security) {
677 				pad = conn->security_size + skb->mark;
678 				pad = conn->size_align - pad;
679 				pad &= conn->size_align - 1;
680 				_debug("pad %zu", pad);
681 				if (pad)
682 					memset(skb_put(skb, pad), 0, pad);
683 			}
684 
685 			seq = atomic_inc_return(&call->sequence);
686 
687 			sp->hdr.epoch = conn->epoch;
688 			sp->hdr.cid = call->cid;
689 			sp->hdr.callNumber = call->call_id;
690 			sp->hdr.seq = htonl(seq);
691 			sp->hdr.serial =
692 				htonl(atomic_inc_return(&conn->serial));
693 			sp->hdr.type = RXRPC_PACKET_TYPE_DATA;
694 			sp->hdr.userStatus = 0;
695 			sp->hdr.securityIndex = conn->security_ix;
696 			sp->hdr._rsvd = 0;
697 			sp->hdr.serviceId = conn->service_id;
698 
699 			sp->hdr.flags = conn->out_clientflag;
700 			if (len == 0 && !more)
701 				sp->hdr.flags |= RXRPC_LAST_PACKET;
702 			else if (CIRC_SPACE(call->acks_head, call->acks_tail,
703 					    call->acks_winsz) > 1)
704 				sp->hdr.flags |= RXRPC_MORE_PACKETS;
705 			if (more && seq & 1)
706 				sp->hdr.flags |= RXRPC_REQUEST_ACK;
707 
708 			ret = rxrpc_secure_packet(
709 				call, skb, skb->mark,
710 				skb->head + sizeof(struct rxrpc_header));
711 			if (ret < 0)
712 				goto out;
713 
714 			memcpy(skb->head, &sp->hdr,
715 			       sizeof(struct rxrpc_header));
716 			rxrpc_queue_packet(call, skb, segment == 0 && !more);
717 			skb = NULL;
718 		}
719 
720 	} while (segment > 0);
721 
722 success:
723 	ret = copied;
724 out:
725 	call->tx_pending = skb;
726 	_leave(" = %d", ret);
727 	return ret;
728 
729 call_aborted:
730 	rxrpc_free_skb(skb);
731 	if (call->state == RXRPC_CALL_NETWORK_ERROR)
732 		ret = call->conn->trans->peer->net_error;
733 	else
734 		ret = -ECONNABORTED;
735 	_leave(" = %d", ret);
736 	return ret;
737 
738 maybe_error:
739 	if (copied)
740 		goto success;
741 	goto out;
742 
743 efault:
744 	ret = -EFAULT;
745 	goto out;
746 }
747