net/can/j1939/main.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 // Copyright (c) 2010-2011 EIA Electronics,
   3 //                         Pieter Beyens <pieter.beyens@eia.be>
   4 // Copyright (c) 2010-2011 EIA Electronics,
   5 //                         Kurt Van Dijck <kurt.van.dijck@eia.be>
   6 // Copyright (c) 2018 Protonic,
   7 //                         Robin van der Gracht <robin@protonic.nl>
   8 // Copyright (c) 2017-2019 Pengutronix,
   9 //                         Marc Kleine-Budde <kernel@pengutronix.de>
  10 // Copyright (c) 2017-2019 Pengutronix,
  11 //                         Oleksij Rempel <kernel@pengutronix.de>
  12
  13 /* Core of can-j1939 that links j1939 to CAN. */
  14
  15 #include <linux/can/can-ml.h>
  16 #include <linux/can/core.h>
  17 #include <linux/can/skb.h>
  18 #include <linux/if_arp.h>
  19 #include <linux/module.h>
  20
  21 #include "j1939-priv.h"
  22
  23 MODULE_DESCRIPTION("PF_CAN SAE J1939");
  24 MODULE_LICENSE("GPL v2");
  25 MODULE_AUTHOR("EIA Electronics (Kurt Van Dijck & Pieter Beyens)");
  26 MODULE_ALIAS("can-proto-" __stringify(CAN_J1939));
  27
  28 /* LOWLEVEL CAN interface */
  29
  30 /* CAN_HDR: #bytes before can_frame data part */
  31 #define J1939_CAN_HDR (offsetof(struct can_frame, data))
  32
  33 /* CAN_FTR: #bytes beyond data part */
  34 #define J1939_CAN_FTR (sizeof(struct can_frame) - J1939_CAN_HDR - \
  35                  sizeof(((struct can_frame *)0)->data))
  36
  37 /* lowest layer */
  38 static void j1939_can_recv(struct sk_buff *iskb, void *data)
  39 {
  40         struct j1939_priv *priv = data;
  41         struct sk_buff *skb;
  42         struct j1939_sk_buff_cb *skcb, *iskcb;
  43         struct can_frame *cf;
  44
  45         /* create a copy of the skb
  46          * j1939 only delivers the real data bytes,
  47          * the header goes into sockaddr.
  48          * j1939 may not touch the incoming skb in such way
  49          */
  50         skb = skb_clone(iskb, GFP_ATOMIC);
  51         if (!skb)
  52                 return;
  53
  54         j1939_priv_get(priv);
  55         can_skb_set_owner(skb, iskb->sk);
  56
  57         /* get a pointer to the header of the skb
  58          * the skb payload (pointer) is moved, so that the next skb_data
  59          * returns the actual payload
  60          */
  61         cf = (void *)skb->data;
  62         skb_pull(skb, J1939_CAN_HDR);
  63
  64         /* fix length, set to dlc, with 8 maximum */
  65         skb_trim(skb, min_t(uint8_t, cf->len, 8));
  66
  67         /* set addr */
  68         skcb = j1939_skb_to_cb(skb);
  69         memset(skcb, 0, sizeof(*skcb));
  70
  71         iskcb = j1939_skb_to_cb(iskb);
  72         skcb->tskey = iskcb->tskey;
  73         skcb->priority = (cf->can_id >> 26) & 0x7;
  74         skcb->addr.sa = cf->can_id;
  75         skcb->addr.pgn = (cf->can_id >> 8) & J1939_PGN_MAX;
  76         /* set default message type */
  77         skcb->addr.type = J1939_TP;
  78         if (j1939_pgn_is_pdu1(skcb->addr.pgn)) {
  79                 /* Type 1: with destination address */
  80                 skcb->addr.da = skcb->addr.pgn;
  81                 /* normalize pgn: strip dst address */
  82                 skcb->addr.pgn &= 0x3ff00;
  83         } else {
  84                 /* set broadcast address */
  85                 skcb->addr.da = J1939_NO_ADDR;
  86         }
  87
  88         /* update localflags */
  89         read_lock_bh(&priv->lock);
  90         if (j1939_address_is_unicast(skcb->addr.sa) &&
  91             priv->ents[skcb->addr.sa].nusers)
  92                 skcb->flags |= J1939_ECU_LOCAL_SRC;
  93         if (j1939_address_is_unicast(skcb->addr.da) &&
  94             priv->ents[skcb->addr.da].nusers)
  95                 skcb->flags |= J1939_ECU_LOCAL_DST;
  96         read_unlock_bh(&priv->lock);
  97
  98         /* deliver into the j1939 stack ... */
  99         j1939_ac_recv(priv, skb);
 100
 101         if (j1939_tp_recv(priv, skb))
 102                 /* this means the transport layer processed the message */
 103                 goto done;
 104
 105         j1939_simple_recv(priv, skb);
 106         j1939_sk_recv(priv, skb);
 107  done:
 108         j1939_priv_put(priv);
 109         kfree_skb(skb);
 110 }
 111
 112 /* NETDEV MANAGEMENT */
 113
 114 /* values for can_rx_(un)register */
 115 #define J1939_CAN_ID CAN_EFF_FLAG
 116 #define J1939_CAN_MASK (CAN_EFF_FLAG | CAN_RTR_FLAG)
 117
 118 static DEFINE_SPINLOCK(j1939_netdev_lock);
 119
 120 static struct j1939_priv *j1939_priv_create(struct net_device *ndev)
 121 {
 122         struct j1939_priv *priv;
 123
 124         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 125         if (!priv)
 126                 return NULL;
 127
 128         rwlock_init(&priv->lock);
 129         INIT_LIST_HEAD(&priv->ecus);
 130         priv->ndev = ndev;
 131         kref_init(&priv->kref);
 132         kref_init(&priv->rx_kref);
 133         dev_hold(ndev);
 134
 135         netdev_dbg(priv->ndev, "%s : 0x%p\n", __func__, priv);
 136
 137         return priv;
 138 }
 139
 140 static inline void j1939_priv_set(struct net_device *ndev,
 141                                   struct j1939_priv *priv)
 142 {
 143         struct can_ml_priv *can_ml = can_get_ml_priv(ndev);
 144
 145         can_ml->j1939_priv = priv;
 146 }
 147
 148 static void __j1939_priv_release(struct kref *kref)
 149 {
 150         struct j1939_priv *priv = container_of(kref, struct j1939_priv, kref);
 151         struct net_device *ndev = priv->ndev;
 152
 153         netdev_dbg(priv->ndev, "%s: 0x%p\n", __func__, priv);
 154
 155         WARN_ON_ONCE(!list_empty(&priv->active_session_list));
 156         WARN_ON_ONCE(!list_empty(&priv->ecus));
 157         WARN_ON_ONCE(!list_empty(&priv->j1939_socks));
 158
 159         dev_put(ndev);
 160         kfree(priv);
 161 }
 162
 163 void j1939_priv_put(struct j1939_priv *priv)
 164 {
 165         kref_put(&priv->kref, __j1939_priv_release);
 166 }
 167
 168 void j1939_priv_get(struct j1939_priv *priv)
 169 {
 170         kref_get(&priv->kref);
 171 }
 172
 173 static int j1939_can_rx_register(struct j1939_priv *priv)
 174 {
 175         struct net_device *ndev = priv->ndev;
 176         int ret;
 177
 178         j1939_priv_get(priv);
 179         ret = can_rx_register(dev_net(ndev), ndev, J1939_CAN_ID, J1939_CAN_MASK,
 180                               j1939_can_recv, priv, "j1939", NULL);
 181         if (ret < 0) {
 182                 j1939_priv_put(priv);
 183                 return ret;
 184         }
 185
 186         return 0;
 187 }
 188
 189 static void j1939_can_rx_unregister(struct j1939_priv *priv)
 190 {
 191         struct net_device *ndev = priv->ndev;
 192
 193         can_rx_unregister(dev_net(ndev), ndev, J1939_CAN_ID, J1939_CAN_MASK,
 194                           j1939_can_recv, priv);
 195
 196         /* The last reference of priv is dropped by the RCU deferred
 197          * j1939_sk_sock_destruct() of the last socket, so we can
 198          * safely drop this reference here.
 199          */
 200         j1939_priv_put(priv);
 201 }
 202
 203 static void __j1939_rx_release(struct kref *kref)
 204         __releases(&j1939_netdev_lock)
 205 {
 206         struct j1939_priv *priv = container_of(kref, struct j1939_priv,
 207                                                rx_kref);
 208
 209         j1939_can_rx_unregister(priv);
 210         j1939_ecu_unmap_all(priv);
 211         j1939_priv_set(priv->ndev, NULL);
 212         spin_unlock(&j1939_netdev_lock);
 213 }
 214
 215 /* get pointer to priv without increasing ref counter */
 216 static inline struct j1939_priv *j1939_ndev_to_priv(struct net_device *ndev)
 217 {
 218         struct can_ml_priv *can_ml = can_get_ml_priv(ndev);
 219
 220         return can_ml->j1939_priv;
 221 }
 222
 223 static struct j1939_priv *j1939_priv_get_by_ndev_locked(struct net_device *ndev)
 224 {
 225         struct j1939_priv *priv;
 226
 227         lockdep_assert_held(&j1939_netdev_lock);
 228
 229         priv = j1939_ndev_to_priv(ndev);
 230         if (priv)
 231                 j1939_priv_get(priv);
 232
 233         return priv;
 234 }
 235
 236 static struct j1939_priv *j1939_priv_get_by_ndev(struct net_device *ndev)
 237 {
 238         struct j1939_priv *priv;
 239
 240         spin_lock(&j1939_netdev_lock);
 241         priv = j1939_priv_get_by_ndev_locked(ndev);
 242         spin_unlock(&j1939_netdev_lock);
 243
 244         return priv;
 245 }
 246
 247 struct j1939_priv *j1939_netdev_start(struct net_device *ndev)
 248 {
 249         struct j1939_priv *priv, *priv_new;
 250         int ret;
 251
 252         spin_lock(&j1939_netdev_lock);
 253         priv = j1939_priv_get_by_ndev_locked(ndev);
 254         if (priv) {
 255                 kref_get(&priv->rx_kref);
 256                 spin_unlock(&j1939_netdev_lock);
 257                 return priv;
 258         }
 259         spin_unlock(&j1939_netdev_lock);
 260
 261         priv = j1939_priv_create(ndev);
 262         if (!priv)
 263                 return ERR_PTR(-ENOMEM);
 264
 265         j1939_tp_init(priv);
 266         spin_lock_init(&priv->j1939_socks_lock);
 267         INIT_LIST_HEAD(&priv->j1939_socks);
 268
 269         spin_lock(&j1939_netdev_lock);
 270         priv_new = j1939_priv_get_by_ndev_locked(ndev);
 271         if (priv_new) {
 272                 /* Someone was faster than us, use their priv and roll
 273                  * back our's.
 274                  */
 275                 kref_get(&priv_new->rx_kref);
 276                 spin_unlock(&j1939_netdev_lock);
 277                 dev_put(ndev);
 278                 kfree(priv);
 279                 return priv_new;
 280         }
 281         j1939_priv_set(ndev, priv);
 282         spin_unlock(&j1939_netdev_lock);
 283
 284         ret = j1939_can_rx_register(priv);
 285         if (ret < 0)
 286                 goto out_priv_put;
 287
 288         return priv;
 289
 290  out_priv_put:
 291         j1939_priv_set(ndev, NULL);
 292         dev_put(ndev);
 293         kfree(priv);
 294
 295         return ERR_PTR(ret);
 296 }
 297
 298 void j1939_netdev_stop(struct j1939_priv *priv)
 299 {
 300         kref_put_lock(&priv->rx_kref, __j1939_rx_release, &j1939_netdev_lock);
 301         j1939_priv_put(priv);
 302 }
 303
 304 int j1939_send_one(struct j1939_priv *priv, struct sk_buff *skb)
 305 {
 306         int ret, dlc;
 307         canid_t canid;
 308         struct j1939_sk_buff_cb *skcb = j1939_skb_to_cb(skb);
 309         struct can_frame *cf;
 310
 311         /* apply sanity checks */
 312         if (j1939_pgn_is_pdu1(skcb->addr.pgn))
 313                 skcb->addr.pgn &= J1939_PGN_PDU1_MAX;
 314         else
 315                 skcb->addr.pgn &= J1939_PGN_MAX;
 316
 317         if (skcb->priority > 7)
 318                 skcb->priority = 6;
 319
 320         ret = j1939_ac_fixup(priv, skb);
 321         if (unlikely(ret))
 322                 goto failed;
 323         dlc = skb->len;
 324
 325         /* re-claim the CAN_HDR from the SKB */
 326         cf = skb_push(skb, J1939_CAN_HDR);
 327
 328         /* make it a full can frame again */
 329         skb_put(skb, J1939_CAN_FTR + (8 - dlc));
 330
 331         canid = CAN_EFF_FLAG |
 332                 (skcb->priority << 26) |
 333                 (skcb->addr.pgn << 8) |
 334                 skcb->addr.sa;
 335         if (j1939_pgn_is_pdu1(skcb->addr.pgn))
 336                 canid |= skcb->addr.da << 8;
 337
 338         cf->can_id = canid;
 339         cf->len = dlc;
 340
 341         return can_send(skb, 1);
 342
 343  failed:
 344         kfree_skb(skb);
 345         return ret;
 346 }
 347
 348 static int j1939_netdev_notify(struct notifier_block *nb,
 349                                unsigned long msg, void *data)
 350 {
 351         struct net_device *ndev = netdev_notifier_info_to_dev(data);
 352         struct can_ml_priv *can_ml = can_get_ml_priv(ndev);
 353         struct j1939_priv *priv;
 354
 355         if (!can_ml)
 356                 goto notify_done;
 357
 358         priv = j1939_priv_get_by_ndev(ndev);
 359         if (!priv)
 360                 goto notify_done;
 361
 362         switch (msg) {
 363         case NETDEV_DOWN:
 364                 j1939_cancel_active_session(priv, NULL);
 365                 j1939_sk_netdev_event_netdown(priv);
 366                 j1939_ecu_unmap_all(priv);
 367                 break;
 368         }
 369
 370         j1939_priv_put(priv);
 371
 372 notify_done:
 373         return NOTIFY_DONE;
 374 }
 375
 376 static struct notifier_block j1939_netdev_notifier = {
 377         .notifier_call = j1939_netdev_notify,
 378 };
 379
 380 /* MODULE interface */
 381 static __init int j1939_module_init(void)
 382 {
 383         int ret;
 384
 385         pr_info("can: SAE J1939\n");
 386
 387         ret = register_netdevice_notifier(&j1939_netdev_notifier);
 388         if (ret)
 389                 goto fail_notifier;
 390
 391         ret = can_proto_register(&j1939_can_proto);
 392         if (ret < 0) {
 393                 pr_err("can: registration of j1939 protocol failed\n");
 394                 goto fail_sk;
 395         }
 396
 397         return 0;
 398
 399  fail_sk:
 400         unregister_netdevice_notifier(&j1939_netdev_notifier);
 401  fail_notifier:
 402         return ret;
 403 }
 404
 405 static __exit void j1939_module_exit(void)
 406 {
 407         can_proto_unregister(&j1939_can_proto);
 408
 409         unregister_netdevice_notifier(&j1939_netdev_notifier);
 410 }
 411
 412 module_init(j1939_module_init);
 413 module_exit(j1939_module_exit);