xref: /linux/net/can/isotp.c (revision 2363088eba2ecccfb643725e4864af73c4226a04)
1 // SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
2 /* isotp.c - ISO 15765-2 CAN transport protocol for protocol family CAN
3  *
4  * This implementation does not provide ISO-TP specific return values to the
5  * userspace.
6  *
7  * - RX path timeout of data reception leads to -ETIMEDOUT
8  * - RX path SN mismatch leads to -EILSEQ
9  * - RX path data reception with wrong padding leads to -EBADMSG
10  * - TX path flowcontrol reception timeout leads to -ECOMM
11  * - TX path flowcontrol reception overflow leads to -EMSGSIZE
12  * - TX path flowcontrol reception with wrong layout/padding leads to -EBADMSG
13  * - when a transfer (tx) is on the run the next write() blocks until it's done
14  * - use CAN_ISOTP_WAIT_TX_DONE flag to block the caller until the PDU is sent
15  * - as we have static buffers the check whether the PDU fits into the buffer
16  *   is done at FF reception time (no support for sending 'wait frames')
17  *
18  * Copyright (c) 2020 Volkswagen Group Electronic Research
19  * All rights reserved.
20  *
21  * Redistribution and use in source and binary forms, with or without
22  * modification, are permitted provided that the following conditions
23  * are met:
24  * 1. Redistributions of source code must retain the above copyright
25  *    notice, this list of conditions and the following disclaimer.
26  * 2. Redistributions in binary form must reproduce the above copyright
27  *    notice, this list of conditions and the following disclaimer in the
28  *    documentation and/or other materials provided with the distribution.
29  * 3. Neither the name of Volkswagen nor the names of its contributors
30  *    may be used to endorse or promote products derived from this software
31  *    without specific prior written permission.
32  *
33  * Alternatively, provided that this notice is retained in full, this
34  * software may be distributed under the terms of the GNU General
35  * Public License ("GPL") version 2, in which case the provisions of the
36  * GPL apply INSTEAD OF those given above.
37  *
38  * The provided data structures and external interfaces from this code
39  * are not restricted to be used by modules with a GPL compatible license.
40  *
41  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
42  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
43  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
44  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
45  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
46  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
47  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
48  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
49  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
50  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
51  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
52  * DAMAGE.
53  */
54 
55 #include <linux/module.h>
56 #include <linux/init.h>
57 #include <linux/interrupt.h>
58 #include <linux/spinlock.h>
59 #include <linux/hrtimer.h>
60 #include <linux/wait.h>
61 #include <linux/uio.h>
62 #include <linux/net.h>
63 #include <linux/netdevice.h>
64 #include <linux/socket.h>
65 #include <linux/if_arp.h>
66 #include <linux/skbuff.h>
67 #include <linux/can.h>
68 #include <linux/can/core.h>
69 #include <linux/can/skb.h>
70 #include <linux/can/isotp.h>
71 #include <linux/slab.h>
72 #include <net/sock.h>
73 #include <net/net_namespace.h>
74 
75 MODULE_DESCRIPTION("PF_CAN isotp 15765-2:2016 protocol");
76 MODULE_LICENSE("Dual BSD/GPL");
77 MODULE_AUTHOR("Oliver Hartkopp <socketcan@hartkopp.net>");
78 MODULE_ALIAS("can-proto-6");
79 
80 #define ISOTP_MIN_NAMELEN CAN_REQUIRED_SIZE(struct sockaddr_can, can_addr.tp)
81 
82 #define SINGLE_MASK(id) (((id) & CAN_EFF_FLAG) ? \
83 			 (CAN_EFF_MASK | CAN_EFF_FLAG | CAN_RTR_FLAG) : \
84 			 (CAN_SFF_MASK | CAN_EFF_FLAG | CAN_RTR_FLAG))
85 
86 /* ISO 15765-2:2016 supports more than 4095 byte per ISO PDU as the FF_DL can
87  * take full 32 bit values (4 Gbyte). We would need some good concept to handle
88  * this between user space and kernel space. For now set the static buffer to
89  * something about 8 kbyte to be able to test this new functionality.
90  */
91 #define DEFAULT_MAX_PDU_SIZE 8300
92 
93 /* maximum PDU size before ISO 15765-2:2016 extension was 4095 */
94 #define MAX_12BIT_PDU_SIZE 4095
95 
96 /* limit the isotp pdu size from the optional module parameter to 1MByte */
97 #define MAX_PDU_SIZE (1025 * 1024U)
98 
99 static unsigned int max_pdu_size __read_mostly = DEFAULT_MAX_PDU_SIZE;
100 module_param(max_pdu_size, uint, 0444);
101 MODULE_PARM_DESC(max_pdu_size, "maximum isotp pdu size (default "
102 		 __stringify(DEFAULT_MAX_PDU_SIZE) ")");
103 
104 /* N_PCI type values in bits 7-4 of N_PCI bytes */
105 #define N_PCI_SF 0x00	/* single frame */
106 #define N_PCI_FF 0x10	/* first frame */
107 #define N_PCI_CF 0x20	/* consecutive frame */
108 #define N_PCI_FC 0x30	/* flow control */
109 
110 #define N_PCI_SZ 1	/* size of the PCI byte #1 */
111 #define SF_PCI_SZ4 1	/* size of SingleFrame PCI including 4 bit SF_DL */
112 #define SF_PCI_SZ8 2	/* size of SingleFrame PCI including 8 bit SF_DL */
113 #define FF_PCI_SZ12 2	/* size of FirstFrame PCI including 12 bit FF_DL */
114 #define FF_PCI_SZ32 6	/* size of FirstFrame PCI including 32 bit FF_DL */
115 #define FC_CONTENT_SZ 3	/* flow control content size in byte (FS/BS/STmin) */
116 
117 #define ISOTP_CHECK_PADDING (CAN_ISOTP_CHK_PAD_LEN | CAN_ISOTP_CHK_PAD_DATA)
118 #define ISOTP_ALL_BC_FLAGS (CAN_ISOTP_SF_BROADCAST | CAN_ISOTP_CF_BROADCAST)
119 
120 /* Flow Status given in FC frame */
121 #define ISOTP_FC_CTS 0		/* clear to send */
122 #define ISOTP_FC_WT 1		/* wait */
123 #define ISOTP_FC_OVFLW 2	/* overflow */
124 
125 #define ISOTP_FC_TIMEOUT 1	/* 1 sec */
126 #define ISOTP_ECHO_TIMEOUT 2	/* 2 secs */
127 
128 enum {
129 	ISOTP_IDLE = 0,
130 	ISOTP_WAIT_FIRST_FC,
131 	ISOTP_WAIT_FC,
132 	ISOTP_WAIT_DATA,
133 	ISOTP_SENDING,
134 	ISOTP_SHUTDOWN,
135 };
136 
137 struct tpcon {
138 	u8 *buf;
139 	unsigned int buflen;
140 	unsigned int len;
141 	unsigned int idx;
142 	u32 state;
143 	u8 bs;
144 	u8 sn;
145 	u8 ll_dl;
146 	u8 sbuf[DEFAULT_MAX_PDU_SIZE];
147 };
148 
149 struct isotp_sock {
150 	struct sock sk;
151 	int bound;
152 	int ifindex;
153 	canid_t txid;
154 	canid_t rxid;
155 	ktime_t tx_gap;
156 	ktime_t lastrxcf_tstamp;
157 	struct hrtimer rxtimer, txtimer, txfrtimer;
158 	struct can_isotp_options opt;
159 	struct can_isotp_fc_options rxfc, txfc;
160 	struct can_isotp_ll_options ll;
161 	u32 frame_txtime;
162 	u32 force_tx_stmin;
163 	u32 force_rx_stmin;
164 	u32 cfecho; /* consecutive frame echo tag */
165 	struct tpcon rx, tx;
166 	struct list_head notifier;
167 	wait_queue_head_t wait;
168 	spinlock_t rx_lock; /* protect single thread state machine */
169 };
170 
171 static LIST_HEAD(isotp_notifier_list);
172 static DEFINE_SPINLOCK(isotp_notifier_lock);
173 static struct isotp_sock *isotp_busy_notifier;
174 
175 static inline struct isotp_sock *isotp_sk(const struct sock *sk)
176 {
177 	return (struct isotp_sock *)sk;
178 }
179 
180 static u32 isotp_bc_flags(struct isotp_sock *so)
181 {
182 	return so->opt.flags & ISOTP_ALL_BC_FLAGS;
183 }
184 
185 static bool isotp_register_rxid(struct isotp_sock *so)
186 {
187 	/* no broadcast modes => register rx_id for FC frame reception */
188 	return (isotp_bc_flags(so) == 0);
189 }
190 
191 static enum hrtimer_restart isotp_rx_timer_handler(struct hrtimer *hrtimer)
192 {
193 	struct isotp_sock *so = container_of(hrtimer, struct isotp_sock,
194 					     rxtimer);
195 	struct sock *sk = &so->sk;
196 
197 	if (so->rx.state == ISOTP_WAIT_DATA) {
198 		/* we did not get new data frames in time */
199 
200 		/* report 'connection timed out' */
201 		sk->sk_err = ETIMEDOUT;
202 		if (!sock_flag(sk, SOCK_DEAD))
203 			sk_error_report(sk);
204 
205 		/* reset rx state */
206 		so->rx.state = ISOTP_IDLE;
207 	}
208 
209 	return HRTIMER_NORESTART;
210 }
211 
212 static int isotp_send_fc(struct sock *sk, int ae, u8 flowstatus)
213 {
214 	struct net_device *dev;
215 	struct sk_buff *nskb;
216 	struct canfd_frame *ncf;
217 	struct isotp_sock *so = isotp_sk(sk);
218 	int can_send_ret;
219 
220 	nskb = alloc_skb(so->ll.mtu + sizeof(struct can_skb_priv), gfp_any());
221 	if (!nskb)
222 		return 1;
223 
224 	dev = dev_get_by_index(sock_net(sk), so->ifindex);
225 	if (!dev) {
226 		kfree_skb(nskb);
227 		return 1;
228 	}
229 
230 	can_skb_reserve(nskb);
231 	can_skb_prv(nskb)->ifindex = dev->ifindex;
232 	can_skb_prv(nskb)->skbcnt = 0;
233 
234 	nskb->dev = dev;
235 	can_skb_set_owner(nskb, sk);
236 	ncf = (struct canfd_frame *)nskb->data;
237 	skb_put_zero(nskb, so->ll.mtu);
238 
239 	/* create & send flow control reply */
240 	ncf->can_id = so->txid;
241 
242 	if (so->opt.flags & CAN_ISOTP_TX_PADDING) {
243 		memset(ncf->data, so->opt.txpad_content, CAN_MAX_DLEN);
244 		ncf->len = CAN_MAX_DLEN;
245 	} else {
246 		ncf->len = ae + FC_CONTENT_SZ;
247 	}
248 
249 	ncf->data[ae] = N_PCI_FC | flowstatus;
250 	ncf->data[ae + 1] = so->rxfc.bs;
251 	ncf->data[ae + 2] = so->rxfc.stmin;
252 
253 	if (ae)
254 		ncf->data[0] = so->opt.ext_address;
255 
256 	ncf->flags = so->ll.tx_flags;
257 
258 	can_send_ret = can_send(nskb, 1);
259 	if (can_send_ret)
260 		pr_notice_once("can-isotp: %s: can_send_ret %pe\n",
261 			       __func__, ERR_PTR(can_send_ret));
262 
263 	dev_put(dev);
264 
265 	/* reset blocksize counter */
266 	so->rx.bs = 0;
267 
268 	/* reset last CF frame rx timestamp for rx stmin enforcement */
269 	so->lastrxcf_tstamp = ktime_set(0, 0);
270 
271 	/* start rx timeout watchdog */
272 	hrtimer_start(&so->rxtimer, ktime_set(ISOTP_FC_TIMEOUT, 0),
273 		      HRTIMER_MODE_REL_SOFT);
274 	return 0;
275 }
276 
277 static void isotp_rcv_skb(struct sk_buff *skb, struct sock *sk)
278 {
279 	struct sockaddr_can *addr = (struct sockaddr_can *)skb->cb;
280 
281 	BUILD_BUG_ON(sizeof(skb->cb) < sizeof(struct sockaddr_can));
282 
283 	memset(addr, 0, sizeof(*addr));
284 	addr->can_family = AF_CAN;
285 	addr->can_ifindex = skb->dev->ifindex;
286 
287 	if (sock_queue_rcv_skb(sk, skb) < 0)
288 		kfree_skb(skb);
289 }
290 
291 static u8 padlen(u8 datalen)
292 {
293 	static const u8 plen[] = {
294 		8, 8, 8, 8, 8, 8, 8, 8, 8,	/* 0 - 8 */
295 		12, 12, 12, 12,			/* 9 - 12 */
296 		16, 16, 16, 16,			/* 13 - 16 */
297 		20, 20, 20, 20,			/* 17 - 20 */
298 		24, 24, 24, 24,			/* 21 - 24 */
299 		32, 32, 32, 32, 32, 32, 32, 32,	/* 25 - 32 */
300 		48, 48, 48, 48, 48, 48, 48, 48,	/* 33 - 40 */
301 		48, 48, 48, 48, 48, 48, 48, 48	/* 41 - 48 */
302 	};
303 
304 	if (datalen > 48)
305 		return 64;
306 
307 	return plen[datalen];
308 }
309 
310 /* check for length optimization and return 1/true when the check fails */
311 static int check_optimized(struct canfd_frame *cf, int start_index)
312 {
313 	/* for CAN_DL <= 8 the start_index is equal to the CAN_DL as the
314 	 * padding would start at this point. E.g. if the padding would
315 	 * start at cf.data[7] cf->len has to be 7 to be optimal.
316 	 * Note: The data[] index starts with zero.
317 	 */
318 	if (cf->len <= CAN_MAX_DLEN)
319 		return (cf->len != start_index);
320 
321 	/* This relation is also valid in the non-linear DLC range, where
322 	 * we need to take care of the minimal next possible CAN_DL.
323 	 * The correct check would be (padlen(cf->len) != padlen(start_index)).
324 	 * But as cf->len can only take discrete values from 12, .., 64 at this
325 	 * point the padlen(cf->len) is always equal to cf->len.
326 	 */
327 	return (cf->len != padlen(start_index));
328 }
329 
330 /* check padding and return 1/true when the check fails */
331 static int check_pad(struct isotp_sock *so, struct canfd_frame *cf,
332 		     int start_index, u8 content)
333 {
334 	int i;
335 
336 	/* no RX_PADDING value => check length of optimized frame length */
337 	if (!(so->opt.flags & CAN_ISOTP_RX_PADDING)) {
338 		if (so->opt.flags & CAN_ISOTP_CHK_PAD_LEN)
339 			return check_optimized(cf, start_index);
340 
341 		/* no valid test against empty value => ignore frame */
342 		return 1;
343 	}
344 
345 	/* check datalength of correctly padded CAN frame */
346 	if ((so->opt.flags & CAN_ISOTP_CHK_PAD_LEN) &&
347 	    cf->len != padlen(cf->len))
348 		return 1;
349 
350 	/* check padding content */
351 	if (so->opt.flags & CAN_ISOTP_CHK_PAD_DATA) {
352 		for (i = start_index; i < cf->len; i++)
353 			if (cf->data[i] != content)
354 				return 1;
355 	}
356 	return 0;
357 }
358 
359 static void isotp_send_cframe(struct isotp_sock *so);
360 
361 static int isotp_rcv_fc(struct isotp_sock *so, struct canfd_frame *cf, int ae)
362 {
363 	struct sock *sk = &so->sk;
364 
365 	if (so->tx.state != ISOTP_WAIT_FC &&
366 	    so->tx.state != ISOTP_WAIT_FIRST_FC)
367 		return 0;
368 
369 	hrtimer_cancel(&so->txtimer);
370 
371 	if ((cf->len < ae + FC_CONTENT_SZ) ||
372 	    ((so->opt.flags & ISOTP_CHECK_PADDING) &&
373 	     check_pad(so, cf, ae + FC_CONTENT_SZ, so->opt.rxpad_content))) {
374 		/* malformed PDU - report 'not a data message' */
375 		sk->sk_err = EBADMSG;
376 		if (!sock_flag(sk, SOCK_DEAD))
377 			sk_error_report(sk);
378 
379 		so->tx.state = ISOTP_IDLE;
380 		wake_up_interruptible(&so->wait);
381 		return 1;
382 	}
383 
384 	/* get communication parameters only from the first FC frame */
385 	if (so->tx.state == ISOTP_WAIT_FIRST_FC) {
386 		so->txfc.bs = cf->data[ae + 1];
387 		so->txfc.stmin = cf->data[ae + 2];
388 
389 		/* fix wrong STmin values according spec */
390 		if (so->txfc.stmin > 0x7F &&
391 		    (so->txfc.stmin < 0xF1 || so->txfc.stmin > 0xF9))
392 			so->txfc.stmin = 0x7F;
393 
394 		so->tx_gap = ktime_set(0, 0);
395 		/* add transmission time for CAN frame N_As */
396 		so->tx_gap = ktime_add_ns(so->tx_gap, so->frame_txtime);
397 		/* add waiting time for consecutive frames N_Cs */
398 		if (so->opt.flags & CAN_ISOTP_FORCE_TXSTMIN)
399 			so->tx_gap = ktime_add_ns(so->tx_gap,
400 						  so->force_tx_stmin);
401 		else if (so->txfc.stmin < 0x80)
402 			so->tx_gap = ktime_add_ns(so->tx_gap,
403 						  so->txfc.stmin * 1000000);
404 		else
405 			so->tx_gap = ktime_add_ns(so->tx_gap,
406 						  (so->txfc.stmin - 0xF0)
407 						  * 100000);
408 		so->tx.state = ISOTP_WAIT_FC;
409 	}
410 
411 	switch (cf->data[ae] & 0x0F) {
412 	case ISOTP_FC_CTS:
413 		so->tx.bs = 0;
414 		so->tx.state = ISOTP_SENDING;
415 		/* send CF frame and enable echo timeout handling */
416 		hrtimer_start(&so->txtimer, ktime_set(ISOTP_ECHO_TIMEOUT, 0),
417 			      HRTIMER_MODE_REL_SOFT);
418 		isotp_send_cframe(so);
419 		break;
420 
421 	case ISOTP_FC_WT:
422 		/* start timer to wait for next FC frame */
423 		hrtimer_start(&so->txtimer, ktime_set(ISOTP_FC_TIMEOUT, 0),
424 			      HRTIMER_MODE_REL_SOFT);
425 		break;
426 
427 	case ISOTP_FC_OVFLW:
428 		/* overflow on receiver side - report 'message too long' */
429 		sk->sk_err = EMSGSIZE;
430 		if (!sock_flag(sk, SOCK_DEAD))
431 			sk_error_report(sk);
432 		fallthrough;
433 
434 	default:
435 		/* stop this tx job */
436 		so->tx.state = ISOTP_IDLE;
437 		wake_up_interruptible(&so->wait);
438 	}
439 	return 0;
440 }
441 
442 static int isotp_rcv_sf(struct sock *sk, struct canfd_frame *cf, int pcilen,
443 			struct sk_buff *skb, int len)
444 {
445 	struct isotp_sock *so = isotp_sk(sk);
446 	struct sk_buff *nskb;
447 
448 	hrtimer_cancel(&so->rxtimer);
449 	so->rx.state = ISOTP_IDLE;
450 
451 	if (!len || len > cf->len - pcilen)
452 		return 1;
453 
454 	if ((so->opt.flags & ISOTP_CHECK_PADDING) &&
455 	    check_pad(so, cf, pcilen + len, so->opt.rxpad_content)) {
456 		/* malformed PDU - report 'not a data message' */
457 		sk->sk_err = EBADMSG;
458 		if (!sock_flag(sk, SOCK_DEAD))
459 			sk_error_report(sk);
460 		return 1;
461 	}
462 
463 	nskb = alloc_skb(len, gfp_any());
464 	if (!nskb)
465 		return 1;
466 
467 	memcpy(skb_put(nskb, len), &cf->data[pcilen], len);
468 
469 	nskb->tstamp = skb->tstamp;
470 	nskb->dev = skb->dev;
471 	isotp_rcv_skb(nskb, sk);
472 	return 0;
473 }
474 
475 static int isotp_rcv_ff(struct sock *sk, struct canfd_frame *cf, int ae)
476 {
477 	struct isotp_sock *so = isotp_sk(sk);
478 	int i;
479 	int off;
480 	int ff_pci_sz;
481 
482 	hrtimer_cancel(&so->rxtimer);
483 	so->rx.state = ISOTP_IDLE;
484 
485 	/* get the used sender LL_DL from the (first) CAN frame data length */
486 	so->rx.ll_dl = padlen(cf->len);
487 
488 	/* the first frame has to use the entire frame up to LL_DL length */
489 	if (cf->len != so->rx.ll_dl)
490 		return 1;
491 
492 	/* get the FF_DL */
493 	so->rx.len = (cf->data[ae] & 0x0F) << 8;
494 	so->rx.len += cf->data[ae + 1];
495 
496 	/* Check for FF_DL escape sequence supporting 32 bit PDU length */
497 	if (so->rx.len) {
498 		ff_pci_sz = FF_PCI_SZ12;
499 	} else {
500 		/* FF_DL = 0 => get real length from next 4 bytes */
501 		so->rx.len = cf->data[ae + 2] << 24;
502 		so->rx.len += cf->data[ae + 3] << 16;
503 		so->rx.len += cf->data[ae + 4] << 8;
504 		so->rx.len += cf->data[ae + 5];
505 		ff_pci_sz = FF_PCI_SZ32;
506 	}
507 
508 	/* take care of a potential SF_DL ESC offset for TX_DL > 8 */
509 	off = (so->rx.ll_dl > CAN_MAX_DLEN) ? 1 : 0;
510 
511 	if (so->rx.len + ae + off + ff_pci_sz < so->rx.ll_dl)
512 		return 1;
513 
514 	/* PDU size > default => try max_pdu_size */
515 	if (so->rx.len > so->rx.buflen && so->rx.buflen < max_pdu_size) {
516 		u8 *newbuf = kmalloc(max_pdu_size, GFP_ATOMIC);
517 
518 		if (newbuf) {
519 			so->rx.buf = newbuf;
520 			so->rx.buflen = max_pdu_size;
521 		}
522 	}
523 
524 	if (so->rx.len > so->rx.buflen) {
525 		/* send FC frame with overflow status */
526 		isotp_send_fc(sk, ae, ISOTP_FC_OVFLW);
527 		return 1;
528 	}
529 
530 	/* copy the first received data bytes */
531 	so->rx.idx = 0;
532 	for (i = ae + ff_pci_sz; i < so->rx.ll_dl; i++)
533 		so->rx.buf[so->rx.idx++] = cf->data[i];
534 
535 	/* initial setup for this pdu reception */
536 	so->rx.sn = 1;
537 	so->rx.state = ISOTP_WAIT_DATA;
538 
539 	/* no creation of flow control frames */
540 	if (so->opt.flags & CAN_ISOTP_LISTEN_MODE)
541 		return 0;
542 
543 	/* send our first FC frame */
544 	isotp_send_fc(sk, ae, ISOTP_FC_CTS);
545 	return 0;
546 }
547 
548 static int isotp_rcv_cf(struct sock *sk, struct canfd_frame *cf, int ae,
549 			struct sk_buff *skb)
550 {
551 	struct isotp_sock *so = isotp_sk(sk);
552 	struct sk_buff *nskb;
553 	int i;
554 
555 	if (so->rx.state != ISOTP_WAIT_DATA)
556 		return 0;
557 
558 	/* drop if timestamp gap is less than force_rx_stmin nano secs */
559 	if (so->opt.flags & CAN_ISOTP_FORCE_RXSTMIN) {
560 		if (ktime_to_ns(ktime_sub(skb->tstamp, so->lastrxcf_tstamp)) <
561 		    so->force_rx_stmin)
562 			return 0;
563 
564 		so->lastrxcf_tstamp = skb->tstamp;
565 	}
566 
567 	hrtimer_cancel(&so->rxtimer);
568 
569 	/* CFs are never longer than the FF */
570 	if (cf->len > so->rx.ll_dl)
571 		return 1;
572 
573 	/* CFs have usually the LL_DL length */
574 	if (cf->len < so->rx.ll_dl) {
575 		/* this is only allowed for the last CF */
576 		if (so->rx.len - so->rx.idx > so->rx.ll_dl - ae - N_PCI_SZ)
577 			return 1;
578 	}
579 
580 	if ((cf->data[ae] & 0x0F) != so->rx.sn) {
581 		/* wrong sn detected - report 'illegal byte sequence' */
582 		sk->sk_err = EILSEQ;
583 		if (!sock_flag(sk, SOCK_DEAD))
584 			sk_error_report(sk);
585 
586 		/* reset rx state */
587 		so->rx.state = ISOTP_IDLE;
588 		return 1;
589 	}
590 	so->rx.sn++;
591 	so->rx.sn %= 16;
592 
593 	for (i = ae + N_PCI_SZ; i < cf->len; i++) {
594 		so->rx.buf[so->rx.idx++] = cf->data[i];
595 		if (so->rx.idx >= so->rx.len)
596 			break;
597 	}
598 
599 	if (so->rx.idx >= so->rx.len) {
600 		/* we are done */
601 		so->rx.state = ISOTP_IDLE;
602 
603 		if ((so->opt.flags & ISOTP_CHECK_PADDING) &&
604 		    check_pad(so, cf, i + 1, so->opt.rxpad_content)) {
605 			/* malformed PDU - report 'not a data message' */
606 			sk->sk_err = EBADMSG;
607 			if (!sock_flag(sk, SOCK_DEAD))
608 				sk_error_report(sk);
609 			return 1;
610 		}
611 
612 		nskb = alloc_skb(so->rx.len, gfp_any());
613 		if (!nskb)
614 			return 1;
615 
616 		memcpy(skb_put(nskb, so->rx.len), so->rx.buf,
617 		       so->rx.len);
618 
619 		nskb->tstamp = skb->tstamp;
620 		nskb->dev = skb->dev;
621 		isotp_rcv_skb(nskb, sk);
622 		return 0;
623 	}
624 
625 	/* perform blocksize handling, if enabled */
626 	if (!so->rxfc.bs || ++so->rx.bs < so->rxfc.bs) {
627 		/* start rx timeout watchdog */
628 		hrtimer_start(&so->rxtimer, ktime_set(ISOTP_FC_TIMEOUT, 0),
629 			      HRTIMER_MODE_REL_SOFT);
630 		return 0;
631 	}
632 
633 	/* no creation of flow control frames */
634 	if (so->opt.flags & CAN_ISOTP_LISTEN_MODE)
635 		return 0;
636 
637 	/* we reached the specified blocksize so->rxfc.bs */
638 	isotp_send_fc(sk, ae, ISOTP_FC_CTS);
639 	return 0;
640 }
641 
642 static void isotp_rcv(struct sk_buff *skb, void *data)
643 {
644 	struct sock *sk = (struct sock *)data;
645 	struct isotp_sock *so = isotp_sk(sk);
646 	struct canfd_frame *cf;
647 	int ae = (so->opt.flags & CAN_ISOTP_EXTEND_ADDR) ? 1 : 0;
648 	u8 n_pci_type, sf_dl;
649 
650 	/* Strictly receive only frames with the configured MTU size
651 	 * => clear separation of CAN2.0 / CAN FD transport channels
652 	 */
653 	if (skb->len != so->ll.mtu)
654 		return;
655 
656 	cf = (struct canfd_frame *)skb->data;
657 
658 	/* if enabled: check reception of my configured extended address */
659 	if (ae && cf->data[0] != so->opt.rx_ext_address)
660 		return;
661 
662 	n_pci_type = cf->data[ae] & 0xF0;
663 
664 	/* Make sure the state changes and data structures stay consistent at
665 	 * CAN frame reception time. This locking is not needed in real world
666 	 * use cases but the inconsistency can be triggered with syzkaller.
667 	 */
668 	spin_lock(&so->rx_lock);
669 
670 	if (so->opt.flags & CAN_ISOTP_HALF_DUPLEX) {
671 		/* check rx/tx path half duplex expectations */
672 		if ((so->tx.state != ISOTP_IDLE && n_pci_type != N_PCI_FC) ||
673 		    (so->rx.state != ISOTP_IDLE && n_pci_type == N_PCI_FC))
674 			goto out_unlock;
675 	}
676 
677 	switch (n_pci_type) {
678 	case N_PCI_FC:
679 		/* tx path: flow control frame containing the FC parameters */
680 		isotp_rcv_fc(so, cf, ae);
681 		break;
682 
683 	case N_PCI_SF:
684 		/* rx path: single frame
685 		 *
686 		 * As we do not have a rx.ll_dl configuration, we can only test
687 		 * if the CAN frames payload length matches the LL_DL == 8
688 		 * requirements - no matter if it's CAN 2.0 or CAN FD
689 		 */
690 
691 		/* get the SF_DL from the N_PCI byte */
692 		sf_dl = cf->data[ae] & 0x0F;
693 
694 		if (cf->len <= CAN_MAX_DLEN) {
695 			isotp_rcv_sf(sk, cf, SF_PCI_SZ4 + ae, skb, sf_dl);
696 		} else {
697 			if (can_is_canfd_skb(skb)) {
698 				/* We have a CAN FD frame and CAN_DL is greater than 8:
699 				 * Only frames with the SF_DL == 0 ESC value are valid.
700 				 *
701 				 * If so take care of the increased SF PCI size
702 				 * (SF_PCI_SZ8) to point to the message content behind
703 				 * the extended SF PCI info and get the real SF_DL
704 				 * length value from the formerly first data byte.
705 				 */
706 				if (sf_dl == 0)
707 					isotp_rcv_sf(sk, cf, SF_PCI_SZ8 + ae, skb,
708 						     cf->data[SF_PCI_SZ4 + ae]);
709 			}
710 		}
711 		break;
712 
713 	case N_PCI_FF:
714 		/* rx path: first frame */
715 		isotp_rcv_ff(sk, cf, ae);
716 		break;
717 
718 	case N_PCI_CF:
719 		/* rx path: consecutive frame */
720 		isotp_rcv_cf(sk, cf, ae, skb);
721 		break;
722 	}
723 
724 out_unlock:
725 	spin_unlock(&so->rx_lock);
726 }
727 
728 static void isotp_fill_dataframe(struct canfd_frame *cf, struct isotp_sock *so,
729 				 int ae, int off)
730 {
731 	int pcilen = N_PCI_SZ + ae + off;
732 	int space = so->tx.ll_dl - pcilen;
733 	int num = min_t(int, so->tx.len - so->tx.idx, space);
734 	int i;
735 
736 	cf->can_id = so->txid;
737 	cf->len = num + pcilen;
738 
739 	if (num < space) {
740 		if (so->opt.flags & CAN_ISOTP_TX_PADDING) {
741 			/* user requested padding */
742 			cf->len = padlen(cf->len);
743 			memset(cf->data, so->opt.txpad_content, cf->len);
744 		} else if (cf->len > CAN_MAX_DLEN) {
745 			/* mandatory padding for CAN FD frames */
746 			cf->len = padlen(cf->len);
747 			memset(cf->data, CAN_ISOTP_DEFAULT_PAD_CONTENT,
748 			       cf->len);
749 		}
750 	}
751 
752 	for (i = 0; i < num; i++)
753 		cf->data[pcilen + i] = so->tx.buf[so->tx.idx++];
754 
755 	if (ae)
756 		cf->data[0] = so->opt.ext_address;
757 }
758 
759 static void isotp_send_cframe(struct isotp_sock *so)
760 {
761 	struct sock *sk = &so->sk;
762 	struct sk_buff *skb;
763 	struct net_device *dev;
764 	struct canfd_frame *cf;
765 	int can_send_ret;
766 	int ae = (so->opt.flags & CAN_ISOTP_EXTEND_ADDR) ? 1 : 0;
767 
768 	dev = dev_get_by_index(sock_net(sk), so->ifindex);
769 	if (!dev)
770 		return;
771 
772 	skb = alloc_skb(so->ll.mtu + sizeof(struct can_skb_priv), GFP_ATOMIC);
773 	if (!skb) {
774 		dev_put(dev);
775 		return;
776 	}
777 
778 	can_skb_reserve(skb);
779 	can_skb_prv(skb)->ifindex = dev->ifindex;
780 	can_skb_prv(skb)->skbcnt = 0;
781 
782 	cf = (struct canfd_frame *)skb->data;
783 	skb_put_zero(skb, so->ll.mtu);
784 
785 	/* create consecutive frame */
786 	isotp_fill_dataframe(cf, so, ae, 0);
787 
788 	/* place consecutive frame N_PCI in appropriate index */
789 	cf->data[ae] = N_PCI_CF | so->tx.sn++;
790 	so->tx.sn %= 16;
791 	so->tx.bs++;
792 
793 	cf->flags = so->ll.tx_flags;
794 
795 	skb->dev = dev;
796 	can_skb_set_owner(skb, sk);
797 
798 	/* cfecho should have been zero'ed by init/isotp_rcv_echo() */
799 	if (so->cfecho)
800 		pr_notice_once("can-isotp: cfecho is %08X != 0\n", so->cfecho);
801 
802 	/* set consecutive frame echo tag */
803 	so->cfecho = *(u32 *)cf->data;
804 
805 	/* send frame with local echo enabled */
806 	can_send_ret = can_send(skb, 1);
807 	if (can_send_ret) {
808 		pr_notice_once("can-isotp: %s: can_send_ret %pe\n",
809 			       __func__, ERR_PTR(can_send_ret));
810 		if (can_send_ret == -ENOBUFS)
811 			pr_notice_once("can-isotp: tx queue is full\n");
812 	}
813 	dev_put(dev);
814 }
815 
816 static void isotp_create_fframe(struct canfd_frame *cf, struct isotp_sock *so,
817 				int ae)
818 {
819 	int i;
820 	int ff_pci_sz;
821 
822 	cf->can_id = so->txid;
823 	cf->len = so->tx.ll_dl;
824 	if (ae)
825 		cf->data[0] = so->opt.ext_address;
826 
827 	/* create N_PCI bytes with 12/32 bit FF_DL data length */
828 	if (so->tx.len > MAX_12BIT_PDU_SIZE) {
829 		/* use 32 bit FF_DL notation */
830 		cf->data[ae] = N_PCI_FF;
831 		cf->data[ae + 1] = 0;
832 		cf->data[ae + 2] = (u8)(so->tx.len >> 24) & 0xFFU;
833 		cf->data[ae + 3] = (u8)(so->tx.len >> 16) & 0xFFU;
834 		cf->data[ae + 4] = (u8)(so->tx.len >> 8) & 0xFFU;
835 		cf->data[ae + 5] = (u8)so->tx.len & 0xFFU;
836 		ff_pci_sz = FF_PCI_SZ32;
837 	} else {
838 		/* use 12 bit FF_DL notation */
839 		cf->data[ae] = (u8)(so->tx.len >> 8) | N_PCI_FF;
840 		cf->data[ae + 1] = (u8)so->tx.len & 0xFFU;
841 		ff_pci_sz = FF_PCI_SZ12;
842 	}
843 
844 	/* add first data bytes depending on ae */
845 	for (i = ae + ff_pci_sz; i < so->tx.ll_dl; i++)
846 		cf->data[i] = so->tx.buf[so->tx.idx++];
847 
848 	so->tx.sn = 1;
849 }
850 
851 static void isotp_rcv_echo(struct sk_buff *skb, void *data)
852 {
853 	struct sock *sk = (struct sock *)data;
854 	struct isotp_sock *so = isotp_sk(sk);
855 	struct canfd_frame *cf = (struct canfd_frame *)skb->data;
856 
857 	/* only handle my own local echo CF/SF skb's (no FF!) */
858 	if (skb->sk != sk || so->cfecho != *(u32 *)cf->data)
859 		return;
860 
861 	/* cancel local echo timeout */
862 	hrtimer_cancel(&so->txtimer);
863 
864 	/* local echo skb with consecutive frame has been consumed */
865 	so->cfecho = 0;
866 
867 	if (so->tx.idx >= so->tx.len) {
868 		/* we are done */
869 		so->tx.state = ISOTP_IDLE;
870 		wake_up_interruptible(&so->wait);
871 		return;
872 	}
873 
874 	if (so->txfc.bs && so->tx.bs >= so->txfc.bs) {
875 		/* stop and wait for FC with timeout */
876 		so->tx.state = ISOTP_WAIT_FC;
877 		hrtimer_start(&so->txtimer, ktime_set(ISOTP_FC_TIMEOUT, 0),
878 			      HRTIMER_MODE_REL_SOFT);
879 		return;
880 	}
881 
882 	/* no gap between data frames needed => use burst mode */
883 	if (!so->tx_gap) {
884 		/* enable echo timeout handling */
885 		hrtimer_start(&so->txtimer, ktime_set(ISOTP_ECHO_TIMEOUT, 0),
886 			      HRTIMER_MODE_REL_SOFT);
887 		isotp_send_cframe(so);
888 		return;
889 	}
890 
891 	/* start timer to send next consecutive frame with correct delay */
892 	hrtimer_start(&so->txfrtimer, so->tx_gap, HRTIMER_MODE_REL_SOFT);
893 }
894 
895 static enum hrtimer_restart isotp_tx_timer_handler(struct hrtimer *hrtimer)
896 {
897 	struct isotp_sock *so = container_of(hrtimer, struct isotp_sock,
898 					     txtimer);
899 	struct sock *sk = &so->sk;
900 
901 	/* don't handle timeouts in IDLE or SHUTDOWN state */
902 	if (so->tx.state == ISOTP_IDLE || so->tx.state == ISOTP_SHUTDOWN)
903 		return HRTIMER_NORESTART;
904 
905 	/* we did not get any flow control or echo frame in time */
906 
907 	/* report 'communication error on send' */
908 	sk->sk_err = ECOMM;
909 	if (!sock_flag(sk, SOCK_DEAD))
910 		sk_error_report(sk);
911 
912 	/* reset tx state */
913 	so->tx.state = ISOTP_IDLE;
914 	wake_up_interruptible(&so->wait);
915 
916 	return HRTIMER_NORESTART;
917 }
918 
919 static enum hrtimer_restart isotp_txfr_timer_handler(struct hrtimer *hrtimer)
920 {
921 	struct isotp_sock *so = container_of(hrtimer, struct isotp_sock,
922 					     txfrtimer);
923 
924 	/* start echo timeout handling and cover below protocol error */
925 	hrtimer_start(&so->txtimer, ktime_set(ISOTP_ECHO_TIMEOUT, 0),
926 		      HRTIMER_MODE_REL_SOFT);
927 
928 	/* cfecho should be consumed by isotp_rcv_echo() here */
929 	if (so->tx.state == ISOTP_SENDING && !so->cfecho)
930 		isotp_send_cframe(so);
931 
932 	return HRTIMER_NORESTART;
933 }
934 
935 static int isotp_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
936 {
937 	struct sock *sk = sock->sk;
938 	struct isotp_sock *so = isotp_sk(sk);
939 	struct sk_buff *skb;
940 	struct net_device *dev;
941 	struct canfd_frame *cf;
942 	int ae = (so->opt.flags & CAN_ISOTP_EXTEND_ADDR) ? 1 : 0;
943 	int wait_tx_done = (so->opt.flags & CAN_ISOTP_WAIT_TX_DONE) ? 1 : 0;
944 	s64 hrtimer_sec = ISOTP_ECHO_TIMEOUT;
945 	int off;
946 	int err;
947 
948 	if (!so->bound || so->tx.state == ISOTP_SHUTDOWN)
949 		return -EADDRNOTAVAIL;
950 
951 wait_free_buffer:
952 	/* we do not support multiple buffers - for now */
953 	if (wq_has_sleeper(&so->wait) && (msg->msg_flags & MSG_DONTWAIT))
954 		return -EAGAIN;
955 
956 	/* wait for complete transmission of current pdu */
957 	err = wait_event_interruptible(so->wait, so->tx.state == ISOTP_IDLE);
958 	if (err)
959 		goto err_event_drop;
960 
961 	if (cmpxchg(&so->tx.state, ISOTP_IDLE, ISOTP_SENDING) != ISOTP_IDLE) {
962 		if (so->tx.state == ISOTP_SHUTDOWN)
963 			return -EADDRNOTAVAIL;
964 
965 		goto wait_free_buffer;
966 	}
967 
968 	/* PDU size > default => try max_pdu_size */
969 	if (size > so->tx.buflen && so->tx.buflen < max_pdu_size) {
970 		u8 *newbuf = kmalloc(max_pdu_size, GFP_KERNEL);
971 
972 		if (newbuf) {
973 			so->tx.buf = newbuf;
974 			so->tx.buflen = max_pdu_size;
975 		}
976 	}
977 
978 	if (!size || size > so->tx.buflen) {
979 		err = -EINVAL;
980 		goto err_out_drop;
981 	}
982 
983 	/* take care of a potential SF_DL ESC offset for TX_DL > 8 */
984 	off = (so->tx.ll_dl > CAN_MAX_DLEN) ? 1 : 0;
985 
986 	/* does the given data fit into a single frame for SF_BROADCAST? */
987 	if ((isotp_bc_flags(so) == CAN_ISOTP_SF_BROADCAST) &&
988 	    (size > so->tx.ll_dl - SF_PCI_SZ4 - ae - off)) {
989 		err = -EINVAL;
990 		goto err_out_drop;
991 	}
992 
993 	err = memcpy_from_msg(so->tx.buf, msg, size);
994 	if (err < 0)
995 		goto err_out_drop;
996 
997 	dev = dev_get_by_index(sock_net(sk), so->ifindex);
998 	if (!dev) {
999 		err = -ENXIO;
1000 		goto err_out_drop;
1001 	}
1002 
1003 	skb = sock_alloc_send_skb(sk, so->ll.mtu + sizeof(struct can_skb_priv),
1004 				  msg->msg_flags & MSG_DONTWAIT, &err);
1005 	if (!skb) {
1006 		dev_put(dev);
1007 		goto err_out_drop;
1008 	}
1009 
1010 	can_skb_reserve(skb);
1011 	can_skb_prv(skb)->ifindex = dev->ifindex;
1012 	can_skb_prv(skb)->skbcnt = 0;
1013 
1014 	so->tx.len = size;
1015 	so->tx.idx = 0;
1016 
1017 	cf = (struct canfd_frame *)skb->data;
1018 	skb_put_zero(skb, so->ll.mtu);
1019 
1020 	/* cfecho should have been zero'ed by init / former isotp_rcv_echo() */
1021 	if (so->cfecho)
1022 		pr_notice_once("can-isotp: uninit cfecho %08X\n", so->cfecho);
1023 
1024 	/* check for single frame transmission depending on TX_DL */
1025 	if (size <= so->tx.ll_dl - SF_PCI_SZ4 - ae - off) {
1026 		/* The message size generally fits into a SingleFrame - good.
1027 		 *
1028 		 * SF_DL ESC offset optimization:
1029 		 *
1030 		 * When TX_DL is greater 8 but the message would still fit
1031 		 * into a 8 byte CAN frame, we can omit the offset.
1032 		 * This prevents a protocol caused length extension from
1033 		 * CAN_DL = 8 to CAN_DL = 12 due to the SF_SL ESC handling.
1034 		 */
1035 		if (size <= CAN_MAX_DLEN - SF_PCI_SZ4 - ae)
1036 			off = 0;
1037 
1038 		isotp_fill_dataframe(cf, so, ae, off);
1039 
1040 		/* place single frame N_PCI w/o length in appropriate index */
1041 		cf->data[ae] = N_PCI_SF;
1042 
1043 		/* place SF_DL size value depending on the SF_DL ESC offset */
1044 		if (off)
1045 			cf->data[SF_PCI_SZ4 + ae] = size;
1046 		else
1047 			cf->data[ae] |= size;
1048 
1049 		/* set CF echo tag for isotp_rcv_echo() (SF-mode) */
1050 		so->cfecho = *(u32 *)cf->data;
1051 	} else {
1052 		/* send first frame */
1053 
1054 		isotp_create_fframe(cf, so, ae);
1055 
1056 		if (isotp_bc_flags(so) == CAN_ISOTP_CF_BROADCAST) {
1057 			/* set timer for FC-less operation (STmin = 0) */
1058 			if (so->opt.flags & CAN_ISOTP_FORCE_TXSTMIN)
1059 				so->tx_gap = ktime_set(0, so->force_tx_stmin);
1060 			else
1061 				so->tx_gap = ktime_set(0, so->frame_txtime);
1062 
1063 			/* disable wait for FCs due to activated block size */
1064 			so->txfc.bs = 0;
1065 
1066 			/* set CF echo tag for isotp_rcv_echo() (CF-mode) */
1067 			so->cfecho = *(u32 *)cf->data;
1068 		} else {
1069 			/* standard flow control check */
1070 			so->tx.state = ISOTP_WAIT_FIRST_FC;
1071 
1072 			/* start timeout for FC */
1073 			hrtimer_sec = ISOTP_FC_TIMEOUT;
1074 
1075 			/* no CF echo tag for isotp_rcv_echo() (FF-mode) */
1076 			so->cfecho = 0;
1077 		}
1078 	}
1079 
1080 	hrtimer_start(&so->txtimer, ktime_set(hrtimer_sec, 0),
1081 		      HRTIMER_MODE_REL_SOFT);
1082 
1083 	/* send the first or only CAN frame */
1084 	cf->flags = so->ll.tx_flags;
1085 
1086 	skb->dev = dev;
1087 	skb->sk = sk;
1088 	err = can_send(skb, 1);
1089 	dev_put(dev);
1090 	if (err) {
1091 		pr_notice_once("can-isotp: %s: can_send_ret %pe\n",
1092 			       __func__, ERR_PTR(err));
1093 
1094 		/* no transmission -> no timeout monitoring */
1095 		hrtimer_cancel(&so->txtimer);
1096 
1097 		/* reset consecutive frame echo tag */
1098 		so->cfecho = 0;
1099 
1100 		goto err_out_drop;
1101 	}
1102 
1103 	if (wait_tx_done) {
1104 		/* wait for complete transmission of current pdu */
1105 		err = wait_event_interruptible(so->wait, so->tx.state == ISOTP_IDLE);
1106 		if (err)
1107 			goto err_event_drop;
1108 
1109 		err = sock_error(sk);
1110 		if (err)
1111 			return err;
1112 	}
1113 
1114 	return size;
1115 
1116 err_event_drop:
1117 	/* got signal: force tx state machine to be idle */
1118 	so->tx.state = ISOTP_IDLE;
1119 	hrtimer_cancel(&so->txfrtimer);
1120 	hrtimer_cancel(&so->txtimer);
1121 err_out_drop:
1122 	/* drop this PDU and unlock a potential wait queue */
1123 	so->tx.state = ISOTP_IDLE;
1124 	wake_up_interruptible(&so->wait);
1125 
1126 	return err;
1127 }
1128 
1129 static int isotp_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
1130 			 int flags)
1131 {
1132 	struct sock *sk = sock->sk;
1133 	struct sk_buff *skb;
1134 	struct isotp_sock *so = isotp_sk(sk);
1135 	int ret = 0;
1136 
1137 	if (flags & ~(MSG_DONTWAIT | MSG_TRUNC | MSG_PEEK | MSG_CMSG_COMPAT))
1138 		return -EINVAL;
1139 
1140 	if (!so->bound)
1141 		return -EADDRNOTAVAIL;
1142 
1143 	skb = skb_recv_datagram(sk, flags, &ret);
1144 	if (!skb)
1145 		return ret;
1146 
1147 	if (size < skb->len)
1148 		msg->msg_flags |= MSG_TRUNC;
1149 	else
1150 		size = skb->len;
1151 
1152 	ret = memcpy_to_msg(msg, skb->data, size);
1153 	if (ret < 0)
1154 		goto out_err;
1155 
1156 	sock_recv_cmsgs(msg, sk, skb);
1157 
1158 	if (msg->msg_name) {
1159 		__sockaddr_check_size(ISOTP_MIN_NAMELEN);
1160 		msg->msg_namelen = ISOTP_MIN_NAMELEN;
1161 		memcpy(msg->msg_name, skb->cb, msg->msg_namelen);
1162 	}
1163 
1164 	/* set length of return value */
1165 	ret = (flags & MSG_TRUNC) ? skb->len : size;
1166 
1167 out_err:
1168 	skb_free_datagram(sk, skb);
1169 
1170 	return ret;
1171 }
1172 
1173 static int isotp_release(struct socket *sock)
1174 {
1175 	struct sock *sk = sock->sk;
1176 	struct isotp_sock *so;
1177 	struct net *net;
1178 
1179 	if (!sk)
1180 		return 0;
1181 
1182 	so = isotp_sk(sk);
1183 	net = sock_net(sk);
1184 
1185 	/* wait for complete transmission of current pdu */
1186 	while (wait_event_interruptible(so->wait, so->tx.state == ISOTP_IDLE) == 0 &&
1187 	       cmpxchg(&so->tx.state, ISOTP_IDLE, ISOTP_SHUTDOWN) != ISOTP_IDLE)
1188 		;
1189 
1190 	/* force state machines to be idle also when a signal occurred */
1191 	so->tx.state = ISOTP_SHUTDOWN;
1192 	so->rx.state = ISOTP_IDLE;
1193 
1194 	spin_lock(&isotp_notifier_lock);
1195 	while (isotp_busy_notifier == so) {
1196 		spin_unlock(&isotp_notifier_lock);
1197 		schedule_timeout_uninterruptible(1);
1198 		spin_lock(&isotp_notifier_lock);
1199 	}
1200 	list_del(&so->notifier);
1201 	spin_unlock(&isotp_notifier_lock);
1202 
1203 	lock_sock(sk);
1204 
1205 	/* remove current filters & unregister */
1206 	if (so->bound) {
1207 		if (so->ifindex) {
1208 			struct net_device *dev;
1209 
1210 			dev = dev_get_by_index(net, so->ifindex);
1211 			if (dev) {
1212 				if (isotp_register_rxid(so))
1213 					can_rx_unregister(net, dev, so->rxid,
1214 							  SINGLE_MASK(so->rxid),
1215 							  isotp_rcv, sk);
1216 
1217 				can_rx_unregister(net, dev, so->txid,
1218 						  SINGLE_MASK(so->txid),
1219 						  isotp_rcv_echo, sk);
1220 				dev_put(dev);
1221 				synchronize_rcu();
1222 			}
1223 		}
1224 	}
1225 
1226 	hrtimer_cancel(&so->txfrtimer);
1227 	hrtimer_cancel(&so->txtimer);
1228 	hrtimer_cancel(&so->rxtimer);
1229 
1230 	so->ifindex = 0;
1231 	so->bound = 0;
1232 
1233 	if (so->rx.buf != so->rx.sbuf)
1234 		kfree(so->rx.buf);
1235 
1236 	if (so->tx.buf != so->tx.sbuf)
1237 		kfree(so->tx.buf);
1238 
1239 	sock_orphan(sk);
1240 	sock->sk = NULL;
1241 
1242 	release_sock(sk);
1243 	sock_put(sk);
1244 
1245 	return 0;
1246 }
1247 
1248 static int isotp_bind(struct socket *sock, struct sockaddr *uaddr, int len)
1249 {
1250 	struct sockaddr_can *addr = (struct sockaddr_can *)uaddr;
1251 	struct sock *sk = sock->sk;
1252 	struct isotp_sock *so = isotp_sk(sk);
1253 	struct net *net = sock_net(sk);
1254 	int ifindex;
1255 	struct net_device *dev;
1256 	canid_t tx_id = addr->can_addr.tp.tx_id;
1257 	canid_t rx_id = addr->can_addr.tp.rx_id;
1258 	int err = 0;
1259 	int notify_enetdown = 0;
1260 
1261 	if (len < ISOTP_MIN_NAMELEN)
1262 		return -EINVAL;
1263 
1264 	if (addr->can_family != AF_CAN)
1265 		return -EINVAL;
1266 
1267 	/* sanitize tx CAN identifier */
1268 	if (tx_id & CAN_EFF_FLAG)
1269 		tx_id &= (CAN_EFF_FLAG | CAN_EFF_MASK);
1270 	else
1271 		tx_id &= CAN_SFF_MASK;
1272 
1273 	/* give feedback on wrong CAN-ID value */
1274 	if (tx_id != addr->can_addr.tp.tx_id)
1275 		return -EINVAL;
1276 
1277 	/* sanitize rx CAN identifier (if needed) */
1278 	if (isotp_register_rxid(so)) {
1279 		if (rx_id & CAN_EFF_FLAG)
1280 			rx_id &= (CAN_EFF_FLAG | CAN_EFF_MASK);
1281 		else
1282 			rx_id &= CAN_SFF_MASK;
1283 
1284 		/* give feedback on wrong CAN-ID value */
1285 		if (rx_id != addr->can_addr.tp.rx_id)
1286 			return -EINVAL;
1287 	}
1288 
1289 	if (!addr->can_ifindex)
1290 		return -ENODEV;
1291 
1292 	lock_sock(sk);
1293 
1294 	if (so->bound) {
1295 		err = -EINVAL;
1296 		goto out;
1297 	}
1298 
1299 	/* ensure different CAN IDs when the rx_id is to be registered */
1300 	if (isotp_register_rxid(so) && rx_id == tx_id) {
1301 		err = -EADDRNOTAVAIL;
1302 		goto out;
1303 	}
1304 
1305 	dev = dev_get_by_index(net, addr->can_ifindex);
1306 	if (!dev) {
1307 		err = -ENODEV;
1308 		goto out;
1309 	}
1310 	if (dev->type != ARPHRD_CAN) {
1311 		dev_put(dev);
1312 		err = -ENODEV;
1313 		goto out;
1314 	}
1315 	if (dev->mtu < so->ll.mtu) {
1316 		dev_put(dev);
1317 		err = -EINVAL;
1318 		goto out;
1319 	}
1320 	if (!(dev->flags & IFF_UP))
1321 		notify_enetdown = 1;
1322 
1323 	ifindex = dev->ifindex;
1324 
1325 	if (isotp_register_rxid(so))
1326 		can_rx_register(net, dev, rx_id, SINGLE_MASK(rx_id),
1327 				isotp_rcv, sk, "isotp", sk);
1328 
1329 	/* no consecutive frame echo skb in flight */
1330 	so->cfecho = 0;
1331 
1332 	/* register for echo skb's */
1333 	can_rx_register(net, dev, tx_id, SINGLE_MASK(tx_id),
1334 			isotp_rcv_echo, sk, "isotpe", sk);
1335 
1336 	dev_put(dev);
1337 
1338 	/* switch to new settings */
1339 	so->ifindex = ifindex;
1340 	so->rxid = rx_id;
1341 	so->txid = tx_id;
1342 	so->bound = 1;
1343 
1344 out:
1345 	release_sock(sk);
1346 
1347 	if (notify_enetdown) {
1348 		sk->sk_err = ENETDOWN;
1349 		if (!sock_flag(sk, SOCK_DEAD))
1350 			sk_error_report(sk);
1351 	}
1352 
1353 	return err;
1354 }
1355 
1356 static int isotp_getname(struct socket *sock, struct sockaddr *uaddr, int peer)
1357 {
1358 	struct sockaddr_can *addr = (struct sockaddr_can *)uaddr;
1359 	struct sock *sk = sock->sk;
1360 	struct isotp_sock *so = isotp_sk(sk);
1361 
1362 	if (peer)
1363 		return -EOPNOTSUPP;
1364 
1365 	memset(addr, 0, ISOTP_MIN_NAMELEN);
1366 	addr->can_family = AF_CAN;
1367 	addr->can_ifindex = so->ifindex;
1368 	addr->can_addr.tp.rx_id = so->rxid;
1369 	addr->can_addr.tp.tx_id = so->txid;
1370 
1371 	return ISOTP_MIN_NAMELEN;
1372 }
1373 
1374 static int isotp_setsockopt_locked(struct socket *sock, int level, int optname,
1375 			    sockptr_t optval, unsigned int optlen)
1376 {
1377 	struct sock *sk = sock->sk;
1378 	struct isotp_sock *so = isotp_sk(sk);
1379 	int ret = 0;
1380 
1381 	if (so->bound)
1382 		return -EISCONN;
1383 
1384 	switch (optname) {
1385 	case CAN_ISOTP_OPTS:
1386 		if (optlen != sizeof(struct can_isotp_options))
1387 			return -EINVAL;
1388 
1389 		if (copy_from_sockptr(&so->opt, optval, optlen))
1390 			return -EFAULT;
1391 
1392 		/* no separate rx_ext_address is given => use ext_address */
1393 		if (!(so->opt.flags & CAN_ISOTP_RX_EXT_ADDR))
1394 			so->opt.rx_ext_address = so->opt.ext_address;
1395 
1396 		/* these broadcast flags are not allowed together */
1397 		if (isotp_bc_flags(so) == ISOTP_ALL_BC_FLAGS) {
1398 			/* CAN_ISOTP_SF_BROADCAST is prioritized */
1399 			so->opt.flags &= ~CAN_ISOTP_CF_BROADCAST;
1400 
1401 			/* give user feedback on wrong config attempt */
1402 			ret = -EINVAL;
1403 		}
1404 
1405 		/* check for frame_txtime changes (0 => no changes) */
1406 		if (so->opt.frame_txtime) {
1407 			if (so->opt.frame_txtime == CAN_ISOTP_FRAME_TXTIME_ZERO)
1408 				so->frame_txtime = 0;
1409 			else
1410 				so->frame_txtime = so->opt.frame_txtime;
1411 		}
1412 		break;
1413 
1414 	case CAN_ISOTP_RECV_FC:
1415 		if (optlen != sizeof(struct can_isotp_fc_options))
1416 			return -EINVAL;
1417 
1418 		if (copy_from_sockptr(&so->rxfc, optval, optlen))
1419 			return -EFAULT;
1420 		break;
1421 
1422 	case CAN_ISOTP_TX_STMIN:
1423 		if (optlen != sizeof(u32))
1424 			return -EINVAL;
1425 
1426 		if (copy_from_sockptr(&so->force_tx_stmin, optval, optlen))
1427 			return -EFAULT;
1428 		break;
1429 
1430 	case CAN_ISOTP_RX_STMIN:
1431 		if (optlen != sizeof(u32))
1432 			return -EINVAL;
1433 
1434 		if (copy_from_sockptr(&so->force_rx_stmin, optval, optlen))
1435 			return -EFAULT;
1436 		break;
1437 
1438 	case CAN_ISOTP_LL_OPTS:
1439 		if (optlen == sizeof(struct can_isotp_ll_options)) {
1440 			struct can_isotp_ll_options ll;
1441 
1442 			if (copy_from_sockptr(&ll, optval, optlen))
1443 				return -EFAULT;
1444 
1445 			/* check for correct ISO 11898-1 DLC data length */
1446 			if (ll.tx_dl != padlen(ll.tx_dl))
1447 				return -EINVAL;
1448 
1449 			if (ll.mtu != CAN_MTU && ll.mtu != CANFD_MTU)
1450 				return -EINVAL;
1451 
1452 			if (ll.mtu == CAN_MTU &&
1453 			    (ll.tx_dl > CAN_MAX_DLEN || ll.tx_flags != 0))
1454 				return -EINVAL;
1455 
1456 			memcpy(&so->ll, &ll, sizeof(ll));
1457 
1458 			/* set ll_dl for tx path to similar place as for rx */
1459 			so->tx.ll_dl = ll.tx_dl;
1460 		} else {
1461 			return -EINVAL;
1462 		}
1463 		break;
1464 
1465 	default:
1466 		ret = -ENOPROTOOPT;
1467 	}
1468 
1469 	return ret;
1470 }
1471 
1472 static int isotp_setsockopt(struct socket *sock, int level, int optname,
1473 			    sockptr_t optval, unsigned int optlen)
1474 
1475 {
1476 	struct sock *sk = sock->sk;
1477 	int ret;
1478 
1479 	if (level != SOL_CAN_ISOTP)
1480 		return -EINVAL;
1481 
1482 	lock_sock(sk);
1483 	ret = isotp_setsockopt_locked(sock, level, optname, optval, optlen);
1484 	release_sock(sk);
1485 	return ret;
1486 }
1487 
1488 static int isotp_getsockopt(struct socket *sock, int level, int optname,
1489 			    char __user *optval, int __user *optlen)
1490 {
1491 	struct sock *sk = sock->sk;
1492 	struct isotp_sock *so = isotp_sk(sk);
1493 	int len;
1494 	void *val;
1495 
1496 	if (level != SOL_CAN_ISOTP)
1497 		return -EINVAL;
1498 	if (get_user(len, optlen))
1499 		return -EFAULT;
1500 	if (len < 0)
1501 		return -EINVAL;
1502 
1503 	switch (optname) {
1504 	case CAN_ISOTP_OPTS:
1505 		len = min_t(int, len, sizeof(struct can_isotp_options));
1506 		val = &so->opt;
1507 		break;
1508 
1509 	case CAN_ISOTP_RECV_FC:
1510 		len = min_t(int, len, sizeof(struct can_isotp_fc_options));
1511 		val = &so->rxfc;
1512 		break;
1513 
1514 	case CAN_ISOTP_TX_STMIN:
1515 		len = min_t(int, len, sizeof(u32));
1516 		val = &so->force_tx_stmin;
1517 		break;
1518 
1519 	case CAN_ISOTP_RX_STMIN:
1520 		len = min_t(int, len, sizeof(u32));
1521 		val = &so->force_rx_stmin;
1522 		break;
1523 
1524 	case CAN_ISOTP_LL_OPTS:
1525 		len = min_t(int, len, sizeof(struct can_isotp_ll_options));
1526 		val = &so->ll;
1527 		break;
1528 
1529 	default:
1530 		return -ENOPROTOOPT;
1531 	}
1532 
1533 	if (put_user(len, optlen))
1534 		return -EFAULT;
1535 	if (copy_to_user(optval, val, len))
1536 		return -EFAULT;
1537 	return 0;
1538 }
1539 
1540 static void isotp_notify(struct isotp_sock *so, unsigned long msg,
1541 			 struct net_device *dev)
1542 {
1543 	struct sock *sk = &so->sk;
1544 
1545 	if (!net_eq(dev_net(dev), sock_net(sk)))
1546 		return;
1547 
1548 	if (so->ifindex != dev->ifindex)
1549 		return;
1550 
1551 	switch (msg) {
1552 	case NETDEV_UNREGISTER:
1553 		lock_sock(sk);
1554 		/* remove current filters & unregister */
1555 		if (so->bound) {
1556 			if (isotp_register_rxid(so))
1557 				can_rx_unregister(dev_net(dev), dev, so->rxid,
1558 						  SINGLE_MASK(so->rxid),
1559 						  isotp_rcv, sk);
1560 
1561 			can_rx_unregister(dev_net(dev), dev, so->txid,
1562 					  SINGLE_MASK(so->txid),
1563 					  isotp_rcv_echo, sk);
1564 		}
1565 
1566 		so->ifindex = 0;
1567 		so->bound  = 0;
1568 		release_sock(sk);
1569 
1570 		sk->sk_err = ENODEV;
1571 		if (!sock_flag(sk, SOCK_DEAD))
1572 			sk_error_report(sk);
1573 		break;
1574 
1575 	case NETDEV_DOWN:
1576 		sk->sk_err = ENETDOWN;
1577 		if (!sock_flag(sk, SOCK_DEAD))
1578 			sk_error_report(sk);
1579 		break;
1580 	}
1581 }
1582 
1583 static int isotp_notifier(struct notifier_block *nb, unsigned long msg,
1584 			  void *ptr)
1585 {
1586 	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
1587 
1588 	if (dev->type != ARPHRD_CAN)
1589 		return NOTIFY_DONE;
1590 	if (msg != NETDEV_UNREGISTER && msg != NETDEV_DOWN)
1591 		return NOTIFY_DONE;
1592 	if (unlikely(isotp_busy_notifier)) /* Check for reentrant bug. */
1593 		return NOTIFY_DONE;
1594 
1595 	spin_lock(&isotp_notifier_lock);
1596 	list_for_each_entry(isotp_busy_notifier, &isotp_notifier_list, notifier) {
1597 		spin_unlock(&isotp_notifier_lock);
1598 		isotp_notify(isotp_busy_notifier, msg, dev);
1599 		spin_lock(&isotp_notifier_lock);
1600 	}
1601 	isotp_busy_notifier = NULL;
1602 	spin_unlock(&isotp_notifier_lock);
1603 	return NOTIFY_DONE;
1604 }
1605 
1606 static int isotp_init(struct sock *sk)
1607 {
1608 	struct isotp_sock *so = isotp_sk(sk);
1609 
1610 	so->ifindex = 0;
1611 	so->bound = 0;
1612 
1613 	so->opt.flags = CAN_ISOTP_DEFAULT_FLAGS;
1614 	so->opt.ext_address = CAN_ISOTP_DEFAULT_EXT_ADDRESS;
1615 	so->opt.rx_ext_address = CAN_ISOTP_DEFAULT_EXT_ADDRESS;
1616 	so->opt.rxpad_content = CAN_ISOTP_DEFAULT_PAD_CONTENT;
1617 	so->opt.txpad_content = CAN_ISOTP_DEFAULT_PAD_CONTENT;
1618 	so->opt.frame_txtime = CAN_ISOTP_DEFAULT_FRAME_TXTIME;
1619 	so->frame_txtime = CAN_ISOTP_DEFAULT_FRAME_TXTIME;
1620 	so->rxfc.bs = CAN_ISOTP_DEFAULT_RECV_BS;
1621 	so->rxfc.stmin = CAN_ISOTP_DEFAULT_RECV_STMIN;
1622 	so->rxfc.wftmax = CAN_ISOTP_DEFAULT_RECV_WFTMAX;
1623 	so->ll.mtu = CAN_ISOTP_DEFAULT_LL_MTU;
1624 	so->ll.tx_dl = CAN_ISOTP_DEFAULT_LL_TX_DL;
1625 	so->ll.tx_flags = CAN_ISOTP_DEFAULT_LL_TX_FLAGS;
1626 
1627 	/* set ll_dl for tx path to similar place as for rx */
1628 	so->tx.ll_dl = so->ll.tx_dl;
1629 
1630 	so->rx.state = ISOTP_IDLE;
1631 	so->tx.state = ISOTP_IDLE;
1632 
1633 	so->rx.buf = so->rx.sbuf;
1634 	so->tx.buf = so->tx.sbuf;
1635 	so->rx.buflen = ARRAY_SIZE(so->rx.sbuf);
1636 	so->tx.buflen = ARRAY_SIZE(so->tx.sbuf);
1637 
1638 	hrtimer_init(&so->rxtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_SOFT);
1639 	so->rxtimer.function = isotp_rx_timer_handler;
1640 	hrtimer_init(&so->txtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_SOFT);
1641 	so->txtimer.function = isotp_tx_timer_handler;
1642 	hrtimer_init(&so->txfrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_SOFT);
1643 	so->txfrtimer.function = isotp_txfr_timer_handler;
1644 
1645 	init_waitqueue_head(&so->wait);
1646 	spin_lock_init(&so->rx_lock);
1647 
1648 	spin_lock(&isotp_notifier_lock);
1649 	list_add_tail(&so->notifier, &isotp_notifier_list);
1650 	spin_unlock(&isotp_notifier_lock);
1651 
1652 	return 0;
1653 }
1654 
1655 static __poll_t isotp_poll(struct file *file, struct socket *sock, poll_table *wait)
1656 {
1657 	struct sock *sk = sock->sk;
1658 	struct isotp_sock *so = isotp_sk(sk);
1659 
1660 	__poll_t mask = datagram_poll(file, sock, wait);
1661 	poll_wait(file, &so->wait, wait);
1662 
1663 	/* Check for false positives due to TX state */
1664 	if ((mask & EPOLLWRNORM) && (so->tx.state != ISOTP_IDLE))
1665 		mask &= ~(EPOLLOUT | EPOLLWRNORM);
1666 
1667 	return mask;
1668 }
1669 
1670 static int isotp_sock_no_ioctlcmd(struct socket *sock, unsigned int cmd,
1671 				  unsigned long arg)
1672 {
1673 	/* no ioctls for socket layer -> hand it down to NIC layer */
1674 	return -ENOIOCTLCMD;
1675 }
1676 
1677 static const struct proto_ops isotp_ops = {
1678 	.family = PF_CAN,
1679 	.release = isotp_release,
1680 	.bind = isotp_bind,
1681 	.connect = sock_no_connect,
1682 	.socketpair = sock_no_socketpair,
1683 	.accept = sock_no_accept,
1684 	.getname = isotp_getname,
1685 	.poll = isotp_poll,
1686 	.ioctl = isotp_sock_no_ioctlcmd,
1687 	.gettstamp = sock_gettstamp,
1688 	.listen = sock_no_listen,
1689 	.shutdown = sock_no_shutdown,
1690 	.setsockopt = isotp_setsockopt,
1691 	.getsockopt = isotp_getsockopt,
1692 	.sendmsg = isotp_sendmsg,
1693 	.recvmsg = isotp_recvmsg,
1694 	.mmap = sock_no_mmap,
1695 };
1696 
1697 static struct proto isotp_proto __read_mostly = {
1698 	.name = "CAN_ISOTP",
1699 	.owner = THIS_MODULE,
1700 	.obj_size = sizeof(struct isotp_sock),
1701 	.init = isotp_init,
1702 };
1703 
1704 static const struct can_proto isotp_can_proto = {
1705 	.type = SOCK_DGRAM,
1706 	.protocol = CAN_ISOTP,
1707 	.ops = &isotp_ops,
1708 	.prot = &isotp_proto,
1709 };
1710 
1711 static struct notifier_block canisotp_notifier = {
1712 	.notifier_call = isotp_notifier
1713 };
1714 
1715 static __init int isotp_module_init(void)
1716 {
1717 	int err;
1718 
1719 	max_pdu_size = max_t(unsigned int, max_pdu_size, MAX_12BIT_PDU_SIZE);
1720 	max_pdu_size = min_t(unsigned int, max_pdu_size, MAX_PDU_SIZE);
1721 
1722 	pr_info("can: isotp protocol (max_pdu_size %d)\n", max_pdu_size);
1723 
1724 	err = can_proto_register(&isotp_can_proto);
1725 	if (err < 0)
1726 		pr_err("can: registration of isotp protocol failed %pe\n", ERR_PTR(err));
1727 	else
1728 		register_netdevice_notifier(&canisotp_notifier);
1729 
1730 	return err;
1731 }
1732 
1733 static __exit void isotp_module_exit(void)
1734 {
1735 	can_proto_unregister(&isotp_can_proto);
1736 	unregister_netdevice_notifier(&canisotp_notifier);
1737 }
1738 
1739 module_init(isotp_module_init);
1740 module_exit(isotp_module_exit);
1741