/* * af_can.c - Protocol family CAN core module * (used by different CAN protocol modules) * * Copyright (c) 2002-2007 Volkswagen Group Electronic Research * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of Volkswagen nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * Alternatively, provided that this notice is retained in full, this * software may be distributed under the terms of the GNU General * Public License ("GPL") version 2, in which case the provisions of the * GPL apply INSTEAD OF those given above. * * The provided data structures and external interfaces from this code * are not restricted to be used by modules with a GPL compatible license. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH * DAMAGE. * * Send feedback to <socketcan-users@lists.berlios.de> * */ #include <linux/module.h> #include <linux/init.h> #include <linux/kmod.h> #include <linux/slab.h> #include <linux/list.h> #include <linux/spinlock.h> #include <linux/rcupdate.h> #include <linux/uaccess.h> #include <linux/net.h> #include <linux/netdevice.h> #include <linux/socket.h> #include <linux/if_ether.h> #include <linux/if_arp.h> #include <linux/skbuff.h> #include <linux/can.h> #include <linux/can/core.h> #include <net/net_namespace.h> #include <net/sock.h> #include "af_can.h" static __initdata const char banner[] = KERN_INFO "can: controller area network core (" CAN_VERSION_STRING ")\n"; MODULE_DESCRIPTION("Controller Area Network PF_CAN core"); MODULE_LICENSE("Dual BSD/GPL"); MODULE_AUTHOR("Urs Thuermann <urs.thuermann@volkswagen.de>, " "Oliver Hartkopp <oliver.hartkopp@volkswagen.de>"); MODULE_ALIAS_NETPROTO(PF_CAN); static int stats_timer __read_mostly = 1; module_param(stats_timer, int, S_IRUGO); MODULE_PARM_DESC(stats_timer, "enable timer for statistics (default:on)"); HLIST_HEAD(can_rx_dev_list); static struct dev_rcv_lists can_rx_alldev_list; static DEFINE_SPINLOCK(can_rcvlists_lock); static struct kmem_cache *rcv_cache __read_mostly; /* table of registered CAN protocols */ static struct can_proto *proto_tab[CAN_NPROTO] __read_mostly; static DEFINE_SPINLOCK(proto_tab_lock); struct timer_list can_stattimer; /* timer for statistics update */ struct s_stats can_stats; /* packet statistics */ struct s_pstats can_pstats; /* receive list statistics */ /* * af_can socket functions */ static int can_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg) { struct sock *sk = sock->sk; switch (cmd) { case SIOCGSTAMP: return sock_get_timestamp(sk, (struct timeval __user *)arg); default: return -ENOIOCTLCMD; } } static void can_sock_destruct(struct sock *sk) { skb_queue_purge(&sk->sk_receive_queue); } static int can_create(struct net *net, struct socket *sock, int protocol) { struct sock *sk; struct can_proto *cp; int err = 0; sock->state = SS_UNCONNECTED; if (protocol < 0 || protocol >= CAN_NPROTO) return -EINVAL; if (net != &init_net) return -EAFNOSUPPORT; #ifdef CONFIG_MODULES /* try to load protocol module kernel is modular */ if (!proto_tab[protocol]) { err = request_module("can-proto-%d", protocol); /* * In case of error we only print a message but don't * return the error code immediately. Below we will * return -EPROTONOSUPPORT */ if (err && printk_ratelimit()) printk(KERN_ERR "can: request_module " "(can-proto-%d) failed.\n", protocol); } #endif spin_lock(&proto_tab_lock); cp = proto_tab[protocol]; if (cp && !try_module_get(cp->prot->owner)) cp = NULL; spin_unlock(&proto_tab_lock); /* check for available protocol and correct usage */ if (!cp) return -EPROTONOSUPPORT; if (cp->type != sock->type) { err = -EPROTONOSUPPORT; goto errout; } if (cp->capability >= 0 && !capable(cp->capability)) { err = -EPERM; goto errout; } sock->ops = cp->ops; sk = sk_alloc(net, PF_CAN, GFP_KERNEL, cp->prot); if (!sk) { err = -ENOMEM; goto errout; } sock_init_data(sock, sk); sk->sk_destruct = can_sock_destruct; if (sk->sk_prot->init) err = sk->sk_prot->init(sk); if (err) { /* release sk on errors */ sock_orphan(sk); sock_put(sk); } errout: module_put(cp->prot->owner); return err; } /* * af_can tx path */ /** * can_send - transmit a CAN frame (optional with local loopback) * @skb: pointer to socket buffer with CAN frame in data section * @loop: loopback for listeners on local CAN sockets (recommended default!) * * Due to the loopback this routine must not be called from hardirq context. * * Return: * 0 on success * -ENETDOWN when the selected interface is down * -ENOBUFS on full driver queue (see net_xmit_errno()) * -ENOMEM when local loopback failed at calling skb_clone() * -EPERM when trying to send on a non-CAN interface * -EINVAL when the skb->data does not contain a valid CAN frame */ int can_send(struct sk_buff *skb, int loop) { struct sk_buff *newskb = NULL; struct can_frame *cf = (struct can_frame *)skb->data; int err; if (skb->len != sizeof(struct can_frame) || cf->can_dlc > 8) { kfree_skb(skb); return -EINVAL; } if (skb->dev->type != ARPHRD_CAN) { kfree_skb(skb); return -EPERM; } if (!(skb->dev->flags & IFF_UP)) { kfree_skb(skb); return -ENETDOWN; } skb->protocol = htons(ETH_P_CAN); skb_reset_network_header(skb); skb_reset_transport_header(skb); if (loop) { /* local loopback of sent CAN frames */ /* indication for the CAN driver: do loopback */ skb->pkt_type = PACKET_LOOPBACK; /* * The reference to the originating sock may be required * by the receiving socket to check whether the frame is * its own. Example: can_raw sockopt CAN_RAW_RECV_OWN_MSGS * Therefore we have to ensure that skb->sk remains the * reference to the originating sock by restoring skb->sk * after each skb_clone() or skb_orphan() usage. */ if (!(skb->dev->flags & IFF_ECHO)) { /* * If the interface is not capable to do loopback * itself, we do it here. */ newskb = skb_clone(skb, GFP_ATOMIC); if (!newskb) { kfree_skb(skb); return -ENOMEM; } newskb->sk = skb->sk; newskb->ip_summed = CHECKSUM_UNNECESSARY; newskb->pkt_type = PACKET_BROADCAST; } } else { /* indication for the CAN driver: no loopback required */ skb->pkt_type = PACKET_HOST; } /* send to netdevice */ err = dev_queue_xmit(skb); if (err > 0) err = net_xmit_errno(err); if (err) { kfree_skb(newskb); return err; } if (newskb) netif_rx_ni(newskb); /* update statistics */ can_stats.tx_frames++; can_stats.tx_frames_delta++; return 0; } EXPORT_SYMBOL(can_send); /* * af_can rx path */ static struct dev_rcv_lists *find_dev_rcv_lists(struct net_device *dev) { struct dev_rcv_lists *d = NULL; struct hlist_node *n; /* * find receive list for this device * * The hlist_for_each_entry*() macros curse through the list * using the pointer variable n and set d to the containing * struct in each list iteration. Therefore, after list * iteration, d is unmodified when the list is empty, and it * points to last list element, when the list is non-empty * but no match in the loop body is found. I.e. d is *not* * NULL when no match is found. We can, however, use the * cursor variable n to decide if a match was found. */ hlist_for_each_entry_rcu(d, n, &can_rx_dev_list, list) { if (d->dev == dev) break; } return n ? d : NULL; } /** * find_rcv_list - determine optimal filterlist inside device filter struct * @can_id: pointer to CAN identifier of a given can_filter * @mask: pointer to CAN mask of a given can_filter * @d: pointer to the device filter struct * * Description: * Returns the optimal filterlist to reduce the filter handling in the * receive path. This function is called by service functions that need * to register or unregister a can_filter in the filter lists. * * A filter matches in general, when * * <received_can_id> & mask == can_id & mask * * so every bit set in the mask (even CAN_EFF_FLAG, CAN_RTR_FLAG) describe * relevant bits for the filter. * * The filter can be inverted (CAN_INV_FILTER bit set in can_id) or it can * filter for error frames (CAN_ERR_FLAG bit set in mask). For error frames * there is a special filterlist and a special rx path filter handling. * * Return: * Pointer to optimal filterlist for the given can_id/mask pair. * Constistency checked mask. * Reduced can_id to have a preprocessed filter compare value. */ static struct hlist_head *find_rcv_list(canid_t *can_id, canid_t *mask, struct dev_rcv_lists *d) { canid_t inv = *can_id & CAN_INV_FILTER; /* save flag before masking */ /* filter for error frames in extra filterlist */ if (*mask & CAN_ERR_FLAG) { /* clear CAN_ERR_FLAG in filter entry */ *mask &= CAN_ERR_MASK; return &d->rx[RX_ERR]; } /* with cleared CAN_ERR_FLAG we have a simple mask/value filterpair */ #define CAN_EFF_RTR_FLAGS (CAN_EFF_FLAG | CAN_RTR_FLAG) /* ensure valid values in can_mask for 'SFF only' frame filtering */ if ((*mask & CAN_EFF_FLAG) && !(*can_id & CAN_EFF_FLAG)) *mask &= (CAN_SFF_MASK | CAN_EFF_RTR_FLAGS); /* reduce condition testing at receive time */ *can_id &= *mask; /* inverse can_id/can_mask filter */ if (inv) return &d->rx[RX_INV]; /* mask == 0 => no condition testing at receive time */ if (!(*mask)) return &d->rx[RX_ALL]; /* extra filterlists for the subscription of a single non-RTR can_id */ if (((*mask & CAN_EFF_RTR_FLAGS) == CAN_EFF_RTR_FLAGS) && !(*can_id & CAN_RTR_FLAG)) { if (*can_id & CAN_EFF_FLAG) { if (*mask == (CAN_EFF_MASK | CAN_EFF_RTR_FLAGS)) { /* RFC: a future use-case for hash-tables? */ return &d->rx[RX_EFF]; } } else { if (*mask == (CAN_SFF_MASK | CAN_EFF_RTR_FLAGS)) return &d->rx_sff[*can_id]; } } /* default: filter via can_id/can_mask */ return &d->rx[RX_FIL]; } /** * can_rx_register - subscribe CAN frames from a specific interface * @dev: pointer to netdevice (NULL => subcribe from 'all' CAN devices list) * @can_id: CAN identifier (see description) * @mask: CAN mask (see description) * @func: callback function on filter match * @data: returned parameter for callback function * @ident: string for calling module indentification * * Description: * Invokes the callback function with the received sk_buff and the given * parameter 'data' on a matching receive filter. A filter matches, when * * <received_can_id> & mask == can_id & mask * * The filter can be inverted (CAN_INV_FILTER bit set in can_id) or it can * filter for error frames (CAN_ERR_FLAG bit set in mask). * * The provided pointer to the sk_buff is guaranteed to be valid as long as * the callback function is running. The callback function must *not* free * the given sk_buff while processing it's task. When the given sk_buff is * needed after the end of the callback function it must be cloned inside * the callback function with skb_clone(). * * Return: * 0 on success * -ENOMEM on missing cache mem to create subscription entry * -ENODEV unknown device */ int can_rx_register(struct net_device *dev, canid_t can_id, canid_t mask, void (*func)(struct sk_buff *, void *), void *data, char *ident) { struct receiver *r; struct hlist_head *rl; struct dev_rcv_lists *d; int err = 0; /* insert new receiver (dev,canid,mask) -> (func,data) */ r = kmem_cache_alloc(rcv_cache, GFP_KERNEL); if (!r) return -ENOMEM; spin_lock(&can_rcvlists_lock); d = find_dev_rcv_lists(dev); if (d) { rl = find_rcv_list(&can_id, &mask, d); r->can_id = can_id; r->mask = mask; r->matches = 0; r->func = func; r->data = data; r->ident = ident; hlist_add_head_rcu(&r->list, rl); d->entries++; can_pstats.rcv_entries++; if (can_pstats.rcv_entries_max < can_pstats.rcv_entries) can_pstats.rcv_entries_max = can_pstats.rcv_entries; } else { kmem_cache_free(rcv_cache, r); err = -ENODEV; } spin_unlock(&can_rcvlists_lock); return err; } EXPORT_SYMBOL(can_rx_register); /* * can_rx_delete_device - rcu callback for dev_rcv_lists structure removal */ static void can_rx_delete_device(struct rcu_head *rp) { struct dev_rcv_lists *d = container_of(rp, struct dev_rcv_lists, rcu); kfree(d); } /* * can_rx_delete_receiver - rcu callback for single receiver entry removal */ static void can_rx_delete_receiver(struct rcu_head *rp) { struct receiver *r = container_of(rp, struct receiver, rcu); kmem_cache_free(rcv_cache, r); } /** * can_rx_unregister - unsubscribe CAN frames from a specific interface * @dev: pointer to netdevice (NULL => unsubcribe from 'all' CAN devices list) * @can_id: CAN identifier * @mask: CAN mask * @func: callback function on filter match * @data: returned parameter for callback function * * Description: * Removes subscription entry depending on given (subscription) values. */ void can_rx_unregister(struct net_device *dev, canid_t can_id, canid_t mask, void (*func)(struct sk_buff *, void *), void *data) { struct receiver *r = NULL; struct hlist_head *rl; struct hlist_node *next; struct dev_rcv_lists *d; spin_lock(&can_rcvlists_lock); d = find_dev_rcv_lists(dev); if (!d) { printk(KERN_ERR "BUG: receive list not found for " "dev %s, id %03X, mask %03X\n", DNAME(dev), can_id, mask); goto out; } rl = find_rcv_list(&can_id, &mask, d); /* * Search the receiver list for the item to delete. This should * exist, since no receiver may be unregistered that hasn't * been registered before. */ hlist_for_each_entry_rcu(r, next, rl, list) { if (r->can_id == can_id && r->mask == mask && r->func == func && r->data == data) break; } /* * Check for bugs in CAN protocol implementations: * If no matching list item was found, the list cursor variable next * will be NULL, while r will point to the last item of the list. */ if (!next) { printk(KERN_ERR "BUG: receive list entry not found for " "dev %s, id %03X, mask %03X\n", DNAME(dev), can_id, mask); r = NULL; d = NULL; goto out; } hlist_del_rcu(&r->list); d->entries--; if (can_pstats.rcv_entries > 0) can_pstats.rcv_entries--; /* remove device structure requested by NETDEV_UNREGISTER */ if (d->remove_on_zero_entries && !d->entries) hlist_del_rcu(&d->list); else d = NULL; out: spin_unlock(&can_rcvlists_lock); /* schedule the receiver item for deletion */ if (r) call_rcu(&r->rcu, can_rx_delete_receiver); /* schedule the device structure for deletion */ if (d) call_rcu(&d->rcu, can_rx_delete_device); } EXPORT_SYMBOL(can_rx_unregister); static inline void deliver(struct sk_buff *skb, struct receiver *r) { r->func(skb, r->data); r->matches++; } static int can_rcv_filter(struct dev_rcv_lists *d, struct sk_buff *skb) { struct receiver *r; struct hlist_node *n; int matches = 0; struct can_frame *cf = (struct can_frame *)skb->data; canid_t can_id = cf->can_id; if (d->entries == 0) return 0; if (can_id & CAN_ERR_FLAG) { /* check for error frame entries only */ hlist_for_each_entry_rcu(r, n, &d->rx[RX_ERR], list) { if (can_id & r->mask) { deliver(skb, r); matches++; } } return matches; } /* check for unfiltered entries */ hlist_for_each_entry_rcu(r, n, &d->rx[RX_ALL], list) { deliver(skb, r); matches++; } /* check for can_id/mask entries */ hlist_for_each_entry_rcu(r, n, &d->rx[RX_FIL], list) { if ((can_id & r->mask) == r->can_id) { deliver(skb, r); matches++; } } /* check for inverted can_id/mask entries */ hlist_for_each_entry_rcu(r, n, &d->rx[RX_INV], list) { if ((can_id & r->mask) != r->can_id) { deliver(skb, r); matches++; } } /* check filterlists for single non-RTR can_ids */ if (can_id & CAN_RTR_FLAG) return matches; if (can_id & CAN_EFF_FLAG) { hlist_for_each_entry_rcu(r, n, &d->rx[RX_EFF], list) { if (r->can_id == can_id) { deliver(skb, r); matches++; } } } else { can_id &= CAN_SFF_MASK; hlist_for_each_entry_rcu(r, n, &d->rx_sff[can_id], list) { deliver(skb, r); matches++; } } return matches; } static int can_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev) { struct dev_rcv_lists *d; struct can_frame *cf = (struct can_frame *)skb->data; int matches; if (!net_eq(dev_net(dev), &init_net)) goto drop; if (WARN_ONCE(dev->type != ARPHRD_CAN || skb->len != sizeof(struct can_frame) || cf->can_dlc > 8, "PF_CAN: dropped non conform skbuf: " "dev type %d, len %d, can_dlc %d\n", dev->type, skb->len, cf->can_dlc)) goto drop; /* update statistics */ can_stats.rx_frames++; can_stats.rx_frames_delta++; rcu_read_lock(); /* deliver the packet to sockets listening on all devices */ matches = can_rcv_filter(&can_rx_alldev_list, skb); /* find receive list for this device */ d = find_dev_rcv_lists(dev); if (d) matches += can_rcv_filter(d, skb); rcu_read_unlock(); /* consume the skbuff allocated by the netdevice driver */ consume_skb(skb); if (matches > 0) { can_stats.matches++; can_stats.matches_delta++; } return NET_RX_SUCCESS; drop: kfree_skb(skb); return NET_RX_DROP; } /* * af_can protocol functions */ /** * can_proto_register - register CAN transport protocol * @cp: pointer to CAN protocol structure * * Return: * 0 on success * -EINVAL invalid (out of range) protocol number * -EBUSY protocol already in use * -ENOBUF if proto_register() fails */ int can_proto_register(struct can_proto *cp) { int proto = cp->protocol; int err = 0; if (proto < 0 || proto >= CAN_NPROTO) { printk(KERN_ERR "can: protocol number %d out of range\n", proto); return -EINVAL; } err = proto_register(cp->prot, 0); if (err < 0) return err; spin_lock(&proto_tab_lock); if (proto_tab[proto]) { printk(KERN_ERR "can: protocol %d already registered\n", proto); err = -EBUSY; } else { proto_tab[proto] = cp; /* use generic ioctl function if not defined by module */ if (!cp->ops->ioctl) cp->ops->ioctl = can_ioctl; } spin_unlock(&proto_tab_lock); if (err < 0) proto_unregister(cp->prot); return err; } EXPORT_SYMBOL(can_proto_register); /** * can_proto_unregister - unregister CAN transport protocol * @cp: pointer to CAN protocol structure */ void can_proto_unregister(struct can_proto *cp) { int proto = cp->protocol; spin_lock(&proto_tab_lock); if (!proto_tab[proto]) { printk(KERN_ERR "BUG: can: protocol %d is not registered\n", proto); } proto_tab[proto] = NULL; spin_unlock(&proto_tab_lock); proto_unregister(cp->prot); } EXPORT_SYMBOL(can_proto_unregister); /* * af_can notifier to create/remove CAN netdevice specific structs */ static int can_notifier(struct notifier_block *nb, unsigned long msg, void *data) { struct net_device *dev = (struct net_device *)data; struct dev_rcv_lists *d; if (!net_eq(dev_net(dev), &init_net)) return NOTIFY_DONE; if (dev->type != ARPHRD_CAN) return NOTIFY_DONE; switch (msg) { case NETDEV_REGISTER: /* * create new dev_rcv_lists for this device * * N.B. zeroing the struct is the correct initialization * for the embedded hlist_head structs. * Another list type, e.g. list_head, would require * explicit initialization. */ d = kzalloc(sizeof(*d), GFP_KERNEL); if (!d) { printk(KERN_ERR "can: allocation of receive list failed\n"); return NOTIFY_DONE; } d->dev = dev; spin_lock(&can_rcvlists_lock); hlist_add_head_rcu(&d->list, &can_rx_dev_list); spin_unlock(&can_rcvlists_lock); break; case NETDEV_UNREGISTER: spin_lock(&can_rcvlists_lock); d = find_dev_rcv_lists(dev); if (d) { if (d->entries) { d->remove_on_zero_entries = 1; d = NULL; } else hlist_del_rcu(&d->list); } else printk(KERN_ERR "can: notifier: receive list not " "found for dev %s\n", dev->name); spin_unlock(&can_rcvlists_lock); if (d) call_rcu(&d->rcu, can_rx_delete_device); break; } return NOTIFY_DONE; } /* * af_can module init/exit functions */ static struct packet_type can_packet __read_mostly = { .type = cpu_to_be16(ETH_P_CAN), .dev = NULL, .func = can_rcv, }; static struct net_proto_family can_family_ops __read_mostly = { .family = PF_CAN, .create = can_create, .owner = THIS_MODULE, }; /* notifier block for netdevice event */ static struct notifier_block can_netdev_notifier __read_mostly = { .notifier_call = can_notifier, }; static __init int can_init(void) { printk(banner); rcv_cache = kmem_cache_create("can_receiver", sizeof(struct receiver), 0, 0, NULL); if (!rcv_cache) return -ENOMEM; /* * Insert can_rx_alldev_list for reception on all devices. * This struct is zero initialized which is correct for the * embedded hlist heads, the dev pointer, and the entries counter. */ spin_lock(&can_rcvlists_lock); hlist_add_head_rcu(&can_rx_alldev_list.list, &can_rx_dev_list); spin_unlock(&can_rcvlists_lock); if (stats_timer) { /* the statistics are updated every second (timer triggered) */ setup_timer(&can_stattimer, can_stat_update, 0); mod_timer(&can_stattimer, round_jiffies(jiffies + HZ)); } else can_stattimer.function = NULL; can_init_proc(); /* protocol register */ sock_register(&can_family_ops); register_netdevice_notifier(&can_netdev_notifier); dev_add_pack(&can_packet); return 0; } static __exit void can_exit(void) { struct dev_rcv_lists *d; struct hlist_node *n, *next; if (stats_timer) del_timer(&can_stattimer); can_remove_proc(); /* protocol unregister */ dev_remove_pack(&can_packet); unregister_netdevice_notifier(&can_netdev_notifier); sock_unregister(PF_CAN); /* remove can_rx_dev_list */ spin_lock(&can_rcvlists_lock); hlist_del(&can_rx_alldev_list.list); hlist_for_each_entry_safe(d, n, next, &can_rx_dev_list, list) { hlist_del(&d->list); kfree(d); } spin_unlock(&can_rcvlists_lock); rcu_barrier(); /* Wait for completion of call_rcu()'s */ kmem_cache_destroy(rcv_cache); } module_init(can_init); module_exit(can_exit);