root/net/can/j1939/address-claim.c

DEFINITIONS

1. j1939_skb_to_name
2. j1939_ac_msg_is_request
3. j1939_ac_verify_outgoing
4. j1939_ac_fixup
5. j1939_ac_process
6. j1939_ac_recv

   1 // SPDX-License-Identifier: GPL-2.0
   2 // Copyright (c) 2010-2011 EIA Electronics,
   3 //                         Kurt Van Dijck <kurt.van.dijck@eia.be>
   4 // Copyright (c) 2010-2011 EIA Electronics,
   5 //                         Pieter Beyens <pieter.beyens@eia.be>
   6 // Copyright (c) 2017-2019 Pengutronix,
   7 //                         Marc Kleine-Budde <kernel@pengutronix.de>
   8 // Copyright (c) 2017-2019 Pengutronix,
   9 //                         Oleksij Rempel <kernel@pengutronix.de>
  10 
  11 /* J1939 Address Claiming.
  12  * Address Claiming in the kernel
  13  * - keeps track of the AC states of ECU's,
  14  * - resolves NAME<=>SA taking into account the AC states of ECU's.
  15  *
  16  * All Address Claim msgs (including host-originated msg) are processed
  17  * at the receive path (a sent msg is always received again via CAN echo).
  18  * As such, the processing of AC msgs is done in the order on which msgs
  19  * are sent on the bus.
  20  *
  21  * This module doesn't send msgs itself (e.g. replies on Address Claims),
  22  * this is the responsibility of a user space application or daemon.
  23  */
  24 
  25 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  26 
  27 #include <linux/netdevice.h>
  28 #include <linux/skbuff.h>
  29 
  30 #include "j1939-priv.h"
  31 
  32 static inline name_t j1939_skb_to_name(const struct sk_buff *skb)
  33 {
  34         return le64_to_cpup((__le64 *)skb->data);
  35 }
  36 
  37 static inline bool j1939_ac_msg_is_request(struct sk_buff *skb)
  38 {
  39         struct j1939_sk_buff_cb *skcb = j1939_skb_to_cb(skb);
  40         int req_pgn;
  41 
  42         if (skb->len < 3 || skcb->addr.pgn != J1939_PGN_REQUEST)
  43                 return false;
  44 
  45         req_pgn = skb->data[0] | (skb->data[1] << 8) | (skb->data[2] << 16);
  46 
  47         return req_pgn == J1939_PGN_ADDRESS_CLAIMED;
  48 }
  49 
  50 static int j1939_ac_verify_outgoing(struct j1939_priv *priv,
  51                                     struct sk_buff *skb)
  52 {
  53         struct j1939_sk_buff_cb *skcb = j1939_skb_to_cb(skb);
  54 
  55         if (skb->len != 8) {
  56                 netdev_notice(priv->ndev, "tx address claim with dlc %i\n",
  57                               skb->len);
  58                 return -EPROTO;
  59         }
  60 
  61         if (skcb->addr.src_name != j1939_skb_to_name(skb)) {
  62                 netdev_notice(priv->ndev, "tx address claim with different name\n");
  63                 return -EPROTO;
  64         }
  65 
  66         if (skcb->addr.sa == J1939_NO_ADDR) {
  67                 netdev_notice(priv->ndev, "tx address claim with broadcast sa\n");
  68                 return -EPROTO;
  69         }
  70 
  71         /* ac must always be a broadcast */
  72         if (skcb->addr.dst_name || skcb->addr.da != J1939_NO_ADDR) {
  73                 netdev_notice(priv->ndev, "tx address claim with dest, not broadcast\n");
  74                 return -EPROTO;
  75         }
  76         return 0;
  77 }
  78 
  79 int j1939_ac_fixup(struct j1939_priv *priv, struct sk_buff *skb)
  80 {
  81         struct j1939_sk_buff_cb *skcb = j1939_skb_to_cb(skb);
  82         int ret;
  83         u8 addr;
  84 
  85         /* network mgmt: address claiming msgs */
  86         if (skcb->addr.pgn == J1939_PGN_ADDRESS_CLAIMED) {
  87                 struct j1939_ecu *ecu;
  88 
  89                 ret = j1939_ac_verify_outgoing(priv, skb);
  90                 /* return both when failure & when successful */
  91                 if (ret < 0)
  92                         return ret;
  93                 ecu = j1939_ecu_get_by_name(priv, skcb->addr.src_name);
  94                 if (!ecu)
  95                         return -ENODEV;
  96 
  97                 if (ecu->addr != skcb->addr.sa)
  98                         /* hold further traffic for ecu, remove from parent */
  99                         j1939_ecu_unmap(ecu);
 100                 j1939_ecu_put(ecu);
 101         } else if (skcb->addr.src_name) {
 102                 /* assign source address */
 103                 addr = j1939_name_to_addr(priv, skcb->addr.src_name);
 104                 if (!j1939_address_is_unicast(addr) &&
 105                     !j1939_ac_msg_is_request(skb)) {
 106                         netdev_notice(priv->ndev, "tx drop: invalid sa for name 0x%016llx\n",
 107                                       skcb->addr.src_name);
 108                         return -EADDRNOTAVAIL;
 109                 }
 110                 skcb->addr.sa = addr;
 111         }
 112 
 113         /* assign destination address */
 114         if (skcb->addr.dst_name) {
 115                 addr = j1939_name_to_addr(priv, skcb->addr.dst_name);
 116                 if (!j1939_address_is_unicast(addr)) {
 117                         netdev_notice(priv->ndev, "tx drop: invalid da for name 0x%016llx\n",
 118                                       skcb->addr.dst_name);
 119                         return -EADDRNOTAVAIL;
 120                 }
 121                 skcb->addr.da = addr;
 122         }
 123         return 0;
 124 }
 125 
 126 static void j1939_ac_process(struct j1939_priv *priv, struct sk_buff *skb)
 127 {
 128         struct j1939_sk_buff_cb *skcb = j1939_skb_to_cb(skb);
 129         struct j1939_ecu *ecu, *prev;
 130         name_t name;
 131 
 132         if (skb->len != 8) {
 133                 netdev_notice(priv->ndev, "rx address claim with wrong dlc %i\n",
 134                               skb->len);
 135                 return;
 136         }
 137 
 138         name = j1939_skb_to_name(skb);
 139         skcb->addr.src_name = name;
 140         if (!name) {
 141                 netdev_notice(priv->ndev, "rx address claim without name\n");
 142                 return;
 143         }
 144 
 145         if (!j1939_address_is_valid(skcb->addr.sa)) {
 146                 netdev_notice(priv->ndev, "rx address claim with broadcast sa\n");
 147                 return;
 148         }
 149 
 150         write_lock_bh(&priv->lock);
 151 
 152         /* Few words on the ECU ref counting:
 153          *
 154          * First we get an ECU handle, either with
 155          * j1939_ecu_get_by_name_locked() (increments the ref counter)
 156          * or j1939_ecu_create_locked() (initializes an ECU object
 157          * with a ref counter of 1).
 158          *
 159          * j1939_ecu_unmap_locked() will decrement the ref counter,
 160          * but only if the ECU was mapped before. So "ecu" still
 161          * belongs to us.
 162          *
 163          * j1939_ecu_timer_start() will increment the ref counter
 164          * before it starts the timer, so we can put the ecu when
 165          * leaving this function.
 166          */
 167         ecu = j1939_ecu_get_by_name_locked(priv, name);
 168         if (!ecu && j1939_address_is_unicast(skcb->addr.sa))
 169                 ecu = j1939_ecu_create_locked(priv, name);
 170 
 171         if (IS_ERR_OR_NULL(ecu))
 172                 goto out_unlock_bh;
 173 
 174         /* cancel pending (previous) address claim */
 175         j1939_ecu_timer_cancel(ecu);
 176 
 177         if (j1939_address_is_idle(skcb->addr.sa)) {
 178                 j1939_ecu_unmap_locked(ecu);
 179                 goto out_ecu_put;
 180         }
 181 
 182         /* save new addr */
 183         if (ecu->addr != skcb->addr.sa)
 184                 j1939_ecu_unmap_locked(ecu);
 185         ecu->addr = skcb->addr.sa;
 186 
 187         prev = j1939_ecu_get_by_addr_locked(priv, skcb->addr.sa);
 188         if (prev) {
 189                 if (ecu->name > prev->name) {
 190                         j1939_ecu_unmap_locked(ecu);
 191                         j1939_ecu_put(prev);
 192                         goto out_ecu_put;
 193                 } else {
 194                         /* kick prev if less or equal */
 195                         j1939_ecu_unmap_locked(prev);
 196                         j1939_ecu_put(prev);
 197                 }
 198         }
 199 
 200         j1939_ecu_timer_start(ecu);
 201  out_ecu_put:
 202         j1939_ecu_put(ecu);
 203  out_unlock_bh:
 204         write_unlock_bh(&priv->lock);
 205 }
 206 
 207 void j1939_ac_recv(struct j1939_priv *priv, struct sk_buff *skb)
 208 {
 209         struct j1939_sk_buff_cb *skcb = j1939_skb_to_cb(skb);
 210         struct j1939_ecu *ecu;
 211 
 212         /* network mgmt */
 213         if (skcb->addr.pgn == J1939_PGN_ADDRESS_CLAIMED) {
 214                 j1939_ac_process(priv, skb);
 215         } else if (j1939_address_is_unicast(skcb->addr.sa)) {
 216                 /* assign source name */
 217                 ecu = j1939_ecu_get_by_addr(priv, skcb->addr.sa);
 218                 if (ecu) {
 219                         skcb->addr.src_name = ecu->name;
 220                         j1939_ecu_put(ecu);
 221                 }
 222         }
 223 
 224         /* assign destination name */
 225         ecu = j1939_ecu_get_by_addr(priv, skcb->addr.da);
 226         if (ecu) {
 227                 skcb->addr.dst_name = ecu->name;
 228                 j1939_ecu_put(ecu);
 229         }
 230 }