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