linux/net/can/j1939/address-claim.c
Devid Antonio Filoni 4ae5e1e97c can: j1939: do not wait 250 ms if the same addr was already claimed
The ISO 11783-5 standard, in "4.5.2 - Address claim requirements", states:
  d) No CF shall begin, or resume, transmission on the network until 250
     ms after it has successfully claimed an address except when
     responding to a request for address-claimed.

But "Figure 6" and "Figure 7" in "4.5.4.2 - Address-claim
prioritization" show that the CF begins the transmission after 250 ms
from the first AC (address-claimed) message even if it sends another AC
message during that time window to resolve the address contention with
another CF.

As stated in "4.4.2.3 - Address-claimed message":
  In order to successfully claim an address, the CF sending an address
  claimed message shall not receive a contending claim from another CF
  for at least 250 ms.

As stated in "4.4.3.2 - NAME management (NM) message":
  1) A commanding CF can
     d) request that a CF with a specified NAME transmit the address-
        claimed message with its current NAME.
  2) A target CF shall
     d) send an address-claimed message in response to a request for a
        matching NAME

Taking the above arguments into account, the 250 ms wait is requested
only during network initialization.

Do not restart the timer on AC message if both the NAME and the address
match and so if the address has already been claimed (timer has expired)
or the AC message has been sent to resolve the contention with another
CF (timer is still running).

Signed-off-by: Devid Antonio Filoni <devid.filoni@egluetechnologies.com>
Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>
Link: https://lore.kernel.org/all/20221125170418.34575-1-devid.filoni@egluetechnologies.com
Fixes: 9d71dd0c70 ("can: add support of SAE J1939 protocol")
Cc: stable@vger.kernel.org
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
2023-02-07 15:00:22 +01:00

271 lines
7.8 KiB
C

// SPDX-License-Identifier: GPL-2.0
// Copyright (c) 2010-2011 EIA Electronics,
// Kurt Van Dijck <kurt.van.dijck@eia.be>
// Copyright (c) 2010-2011 EIA Electronics,
// Pieter Beyens <pieter.beyens@eia.be>
// Copyright (c) 2017-2019 Pengutronix,
// Marc Kleine-Budde <kernel@pengutronix.de>
// Copyright (c) 2017-2019 Pengutronix,
// Oleksij Rempel <kernel@pengutronix.de>
/* J1939 Address Claiming.
* Address Claiming in the kernel
* - keeps track of the AC states of ECU's,
* - resolves NAME<=>SA taking into account the AC states of ECU's.
*
* All Address Claim msgs (including host-originated msg) are processed
* at the receive path (a sent msg is always received again via CAN echo).
* As such, the processing of AC msgs is done in the order on which msgs
* are sent on the bus.
*
* This module doesn't send msgs itself (e.g. replies on Address Claims),
* this is the responsibility of a user space application or daemon.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include "j1939-priv.h"
static inline name_t j1939_skb_to_name(const struct sk_buff *skb)
{
return le64_to_cpup((__le64 *)skb->data);
}
static inline bool j1939_ac_msg_is_request(struct sk_buff *skb)
{
struct j1939_sk_buff_cb *skcb = j1939_skb_to_cb(skb);
int req_pgn;
if (skb->len < 3 || skcb->addr.pgn != J1939_PGN_REQUEST)
return false;
req_pgn = skb->data[0] | (skb->data[1] << 8) | (skb->data[2] << 16);
return req_pgn == J1939_PGN_ADDRESS_CLAIMED;
}
static int j1939_ac_verify_outgoing(struct j1939_priv *priv,
struct sk_buff *skb)
{
struct j1939_sk_buff_cb *skcb = j1939_skb_to_cb(skb);
if (skb->len != 8) {
netdev_notice(priv->ndev, "tx address claim with dlc %i\n",
skb->len);
return -EPROTO;
}
if (skcb->addr.src_name != j1939_skb_to_name(skb)) {
netdev_notice(priv->ndev, "tx address claim with different name\n");
return -EPROTO;
}
if (skcb->addr.sa == J1939_NO_ADDR) {
netdev_notice(priv->ndev, "tx address claim with broadcast sa\n");
return -EPROTO;
}
/* ac must always be a broadcast */
if (skcb->addr.dst_name || skcb->addr.da != J1939_NO_ADDR) {
netdev_notice(priv->ndev, "tx address claim with dest, not broadcast\n");
return -EPROTO;
}
return 0;
}
int j1939_ac_fixup(struct j1939_priv *priv, struct sk_buff *skb)
{
struct j1939_sk_buff_cb *skcb = j1939_skb_to_cb(skb);
int ret;
u8 addr;
/* network mgmt: address claiming msgs */
if (skcb->addr.pgn == J1939_PGN_ADDRESS_CLAIMED) {
struct j1939_ecu *ecu;
ret = j1939_ac_verify_outgoing(priv, skb);
/* return both when failure & when successful */
if (ret < 0)
return ret;
ecu = j1939_ecu_get_by_name(priv, skcb->addr.src_name);
if (!ecu)
return -ENODEV;
if (ecu->addr != skcb->addr.sa)
/* hold further traffic for ecu, remove from parent */
j1939_ecu_unmap(ecu);
j1939_ecu_put(ecu);
} else if (skcb->addr.src_name) {
/* assign source address */
addr = j1939_name_to_addr(priv, skcb->addr.src_name);
if (!j1939_address_is_unicast(addr) &&
!j1939_ac_msg_is_request(skb)) {
netdev_notice(priv->ndev, "tx drop: invalid sa for name 0x%016llx\n",
skcb->addr.src_name);
return -EADDRNOTAVAIL;
}
skcb->addr.sa = addr;
}
/* assign destination address */
if (skcb->addr.dst_name) {
addr = j1939_name_to_addr(priv, skcb->addr.dst_name);
if (!j1939_address_is_unicast(addr)) {
netdev_notice(priv->ndev, "tx drop: invalid da for name 0x%016llx\n",
skcb->addr.dst_name);
return -EADDRNOTAVAIL;
}
skcb->addr.da = addr;
}
return 0;
}
static void j1939_ac_process(struct j1939_priv *priv, struct sk_buff *skb)
{
struct j1939_sk_buff_cb *skcb = j1939_skb_to_cb(skb);
struct j1939_ecu *ecu, *prev;
name_t name;
if (skb->len != 8) {
netdev_notice(priv->ndev, "rx address claim with wrong dlc %i\n",
skb->len);
return;
}
name = j1939_skb_to_name(skb);
skcb->addr.src_name = name;
if (!name) {
netdev_notice(priv->ndev, "rx address claim without name\n");
return;
}
if (!j1939_address_is_valid(skcb->addr.sa)) {
netdev_notice(priv->ndev, "rx address claim with broadcast sa\n");
return;
}
write_lock_bh(&priv->lock);
/* Few words on the ECU ref counting:
*
* First we get an ECU handle, either with
* j1939_ecu_get_by_name_locked() (increments the ref counter)
* or j1939_ecu_create_locked() (initializes an ECU object
* with a ref counter of 1).
*
* j1939_ecu_unmap_locked() will decrement the ref counter,
* but only if the ECU was mapped before. So "ecu" still
* belongs to us.
*
* j1939_ecu_timer_start() will increment the ref counter
* before it starts the timer, so we can put the ecu when
* leaving this function.
*/
ecu = j1939_ecu_get_by_name_locked(priv, name);
if (ecu && ecu->addr == skcb->addr.sa) {
/* The ISO 11783-5 standard, in "4.5.2 - Address claim
* requirements", states:
* d) No CF shall begin, or resume, transmission on the
* network until 250 ms after it has successfully claimed
* an address except when responding to a request for
* address-claimed.
*
* But "Figure 6" and "Figure 7" in "4.5.4.2 - Address-claim
* prioritization" show that the CF begins the transmission
* after 250 ms from the first AC (address-claimed) message
* even if it sends another AC message during that time window
* to resolve the address contention with another CF.
*
* As stated in "4.4.2.3 - Address-claimed message":
* In order to successfully claim an address, the CF sending
* an address claimed message shall not receive a contending
* claim from another CF for at least 250 ms.
*
* As stated in "4.4.3.2 - NAME management (NM) message":
* 1) A commanding CF can
* d) request that a CF with a specified NAME transmit
* the address-claimed message with its current NAME.
* 2) A target CF shall
* d) send an address-claimed message in response to a
* request for a matching NAME
*
* Taking the above arguments into account, the 250 ms wait is
* requested only during network initialization.
*
* Do not restart the timer on AC message if both the NAME and
* the address match and so if the address has already been
* claimed (timer has expired) or the AC message has been sent
* to resolve the contention with another CF (timer is still
* running).
*/
goto out_ecu_put;
}
if (!ecu && j1939_address_is_unicast(skcb->addr.sa))
ecu = j1939_ecu_create_locked(priv, name);
if (IS_ERR_OR_NULL(ecu))
goto out_unlock_bh;
/* cancel pending (previous) address claim */
j1939_ecu_timer_cancel(ecu);
if (j1939_address_is_idle(skcb->addr.sa)) {
j1939_ecu_unmap_locked(ecu);
goto out_ecu_put;
}
/* save new addr */
if (ecu->addr != skcb->addr.sa)
j1939_ecu_unmap_locked(ecu);
ecu->addr = skcb->addr.sa;
prev = j1939_ecu_get_by_addr_locked(priv, skcb->addr.sa);
if (prev) {
if (ecu->name > prev->name) {
j1939_ecu_unmap_locked(ecu);
j1939_ecu_put(prev);
goto out_ecu_put;
} else {
/* kick prev if less or equal */
j1939_ecu_unmap_locked(prev);
j1939_ecu_put(prev);
}
}
j1939_ecu_timer_start(ecu);
out_ecu_put:
j1939_ecu_put(ecu);
out_unlock_bh:
write_unlock_bh(&priv->lock);
}
void j1939_ac_recv(struct j1939_priv *priv, struct sk_buff *skb)
{
struct j1939_sk_buff_cb *skcb = j1939_skb_to_cb(skb);
struct j1939_ecu *ecu;
/* network mgmt */
if (skcb->addr.pgn == J1939_PGN_ADDRESS_CLAIMED) {
j1939_ac_process(priv, skb);
} else if (j1939_address_is_unicast(skcb->addr.sa)) {
/* assign source name */
ecu = j1939_ecu_get_by_addr(priv, skcb->addr.sa);
if (ecu) {
skcb->addr.src_name = ecu->name;
j1939_ecu_put(ecu);
}
}
/* assign destination name */
ecu = j1939_ecu_get_by_addr(priv, skcb->addr.da);
if (ecu) {
skcb->addr.dst_name = ecu->name;
j1939_ecu_put(ecu);
}
}