Commit 96d1c81e authored by Oliver Hartkopp's avatar Oliver Hartkopp Committed by Marc Kleine-Budde
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can: isotp: add module parameter for maximum pdu size 

With ISO 15765-2:2016 the PDU size is not limited to 2^12 - 1 (4095)
bytes but can be represented as a 32 bit unsigned integer value which
allows 2^32 - 1 bytes (~4GB). The use-cases like automotive unified
diagnostic services (UDS) and flashing of ECUs still use the small
static buffers which are provided at socket creation time.

When a use-case requires to transfer PDUs up to 1025 kByte the maximum
PDU size can now be extended by setting the module parameter
max_pdu_size. The extended size buffers are only allocated on a
per-socket/connection base when needed at run-time.

changes since v2: https://lore.kernel.org/all/20230313172510.3851-1-socketcan@hartkopp.net
- use ARRAY_SIZE() to reference DEFAULT_MAX_PDU_SIZE only at one place

changes since v1: https://lore.kernel.org/all/20230311143446.3183-1-socketcan@hartkopp.net
- limit the minimum 'max_pdu_size' to 4095 to maintain the classic
  behavior before ISO 15765-2:2016

Link: https://github.com/raspberrypi/linux/issues/5371


Signed-off-by: default avatarOliver Hartkopp <socketcan@hartkopp.net>
Link: https://lore.kernel.org/all/20230326115911.15094-1-socketcan@hartkopp.net


Signed-off-by: default avatarMarc Kleine-Budde <mkl@pengutronix.de>
parent 4cee0fb9

net/can/isotp.c

+56 −9
Original line number Diff line number Diff line
@@ -85,10 +85,21 @@ MODULE_ALIAS("can-proto-6"); 


/* ISO 15765-2:2016 supports more than 4095 byte per ISO PDU as the FF_DL can

 * take full 32 bit values (4 Gbyte). We would need some good concept to handle

 * this between user space and kernel space. For now increase the static buffer

 * to something about 64 kbyte to be able to test this new functionality.

 * this between user space and kernel space. For now set the static buffer to

 * something about 8 kbyte to be able to test this new functionality.

 */

#define MAX_MSG_LENGTH 66000

#define DEFAULT_MAX_PDU_SIZE 8300



/* maximum PDU size before ISO 15765-2:2016 extension was 4095 */

#define MAX_12BIT_PDU_SIZE 4095



/* limit the isotp pdu size from the optional module parameter to 1MByte */

#define MAX_PDU_SIZE (1025 * 1024U)



static unsigned int max_pdu_size __read_mostly = DEFAULT_MAX_PDU_SIZE;

module_param(max_pdu_size, uint, 0444);

MODULE_PARM_DESC(max_pdu_size, "maximum isotp pdu size (default "

		 __stringify(DEFAULT_MAX_PDU_SIZE) ")");



/* N_PCI type values in bits 7-4 of N_PCI bytes */

#define N_PCI_SF 0x00	/* single frame */
@@ -123,13 +134,15 @@ enum { 
};



struct tpcon {

	unsigned int idx;

	u8 *buf;

	unsigned int buflen;

	unsigned int len;

	unsigned int idx;

	u32 state;

	u8 bs;

	u8 sn;

	u8 ll_dl;

	u8 buf[MAX_MSG_LENGTH + 1];

	u8 sbuf[DEFAULT_MAX_PDU_SIZE];

};



struct isotp_sock {
@@ -503,7 +516,17 @@ static int isotp_rcv_ff(struct sock *sk, struct canfd_frame *cf, int ae) 
	if (so->rx.len + ae + off + ff_pci_sz < so->rx.ll_dl)

		return 1;



	if (so->rx.len > MAX_MSG_LENGTH) {

	/* PDU size > default => try max_pdu_size */

	if (so->rx.len > so->rx.buflen && so->rx.buflen < max_pdu_size) {

		u8 *newbuf = kmalloc(max_pdu_size, GFP_ATOMIC);



		if (newbuf) {

			so->rx.buf = newbuf;

			so->rx.buflen = max_pdu_size;

		}

	}



	if (so->rx.len > so->rx.buflen) {

		/* send FC frame with overflow status */

		isotp_send_fc(sk, ae, ISOTP_FC_OVFLW);

		return 1;
@@ -807,7 +830,7 @@ static void isotp_create_fframe(struct canfd_frame *cf, struct isotp_sock *so, 
		cf->data[0] = so->opt.ext_address;



	/* create N_PCI bytes with 12/32 bit FF_DL data length */

	if (so->tx.len > 4095) {

	if (so->tx.len > MAX_12BIT_PDU_SIZE) {

		/* use 32 bit FF_DL notation */

		cf->data[ae] = N_PCI_FF;

		cf->data[ae + 1] = 0;
@@ -947,7 +970,17 @@ static int isotp_sendmsg(struct socket *sock, struct msghdr *msg, size_t size) 
		so->tx.state = ISOTP_SENDING;

	}



	if (!size || size > MAX_MSG_LENGTH) {

	/* PDU size > default => try max_pdu_size */

	if (size > so->tx.buflen && so->tx.buflen < max_pdu_size) {

		u8 *newbuf = kmalloc(max_pdu_size, GFP_KERNEL);



		if (newbuf) {

			so->tx.buf = newbuf;

			so->tx.buflen = max_pdu_size;

		}

	}



	if (!size || size > so->tx.buflen) {

		err = -EINVAL;

		goto err_out_drop;

	}
@@ -1195,6 +1228,12 @@ static int isotp_release(struct socket *sock) 
	so->ifindex = 0;

	so->bound = 0;



	if (so->rx.buf != so->rx.sbuf)

		kfree(so->rx.buf);



	if (so->tx.buf != so->tx.sbuf)

		kfree(so->tx.buf);



	sock_orphan(sk);

	sock->sk = NULL;
@@ -1591,6 +1630,11 @@ static int isotp_init(struct sock *sk) 
	so->rx.state = ISOTP_IDLE;

	so->tx.state = ISOTP_IDLE;



	so->rx.buf = so->rx.sbuf;

	so->tx.buf = so->tx.sbuf;

	so->rx.buflen = ARRAY_SIZE(so->rx.sbuf);

	so->tx.buflen = ARRAY_SIZE(so->tx.sbuf);



	hrtimer_init(&so->rxtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_SOFT);

	so->rxtimer.function = isotp_rx_timer_handler;

	hrtimer_init(&so->txtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_SOFT);
@@ -1658,7 +1702,10 @@ static __init int isotp_module_init(void) 
{

	int err;



	pr_info("can: isotp protocol\n");

	max_pdu_size = max_t(unsigned int, max_pdu_size, MAX_12BIT_PDU_SIZE);

	max_pdu_size = min_t(unsigned int, max_pdu_size, MAX_PDU_SIZE);



	pr_info("can: isotp protocol (max_pdu_size %d)\n", max_pdu_size);



	err = can_proto_register(&isotp_can_proto);

	if (err < 0)