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// 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 && 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);
}
}
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