linux/net/can/af_can.c
Eric Dumazet f1712c7371 can: Fix kernel panic at security_sock_rcv_skb
Zhang Yanmin reported crashes [1] and provided a patch adding a
synchronize_rcu() call in can_rx_unregister()

The main problem seems that the sockets themselves are not RCU
protected.

If CAN uses RCU for delivery, then sockets should be freed only after
one RCU grace period.

Recent kernels could use sock_set_flag(sk, SOCK_RCU_FREE), but let's
ease stable backports with the following fix instead.

[1]
BUG: unable to handle kernel NULL pointer dereference at (null)
IP: [<ffffffff81495e25>] selinux_socket_sock_rcv_skb+0x65/0x2a0

Call Trace:
 <IRQ>
 [<ffffffff81485d8c>] security_sock_rcv_skb+0x4c/0x60
 [<ffffffff81d55771>] sk_filter+0x41/0x210
 [<ffffffff81d12913>] sock_queue_rcv_skb+0x53/0x3a0
 [<ffffffff81f0a2b3>] raw_rcv+0x2a3/0x3c0
 [<ffffffff81f06eab>] can_rcv_filter+0x12b/0x370
 [<ffffffff81f07af9>] can_receive+0xd9/0x120
 [<ffffffff81f07beb>] can_rcv+0xab/0x100
 [<ffffffff81d362ac>] __netif_receive_skb_core+0xd8c/0x11f0
 [<ffffffff81d36734>] __netif_receive_skb+0x24/0xb0
 [<ffffffff81d37f67>] process_backlog+0x127/0x280
 [<ffffffff81d36f7b>] net_rx_action+0x33b/0x4f0
 [<ffffffff810c88d4>] __do_softirq+0x184/0x440
 [<ffffffff81f9e86c>] do_softirq_own_stack+0x1c/0x30
 <EOI>
 [<ffffffff810c76fb>] do_softirq.part.18+0x3b/0x40
 [<ffffffff810c8bed>] do_softirq+0x1d/0x20
 [<ffffffff81d30085>] netif_rx_ni+0xe5/0x110
 [<ffffffff8199cc87>] slcan_receive_buf+0x507/0x520
 [<ffffffff8167ef7c>] flush_to_ldisc+0x21c/0x230
 [<ffffffff810e3baf>] process_one_work+0x24f/0x670
 [<ffffffff810e44ed>] worker_thread+0x9d/0x6f0
 [<ffffffff810e4450>] ? rescuer_thread+0x480/0x480
 [<ffffffff810ebafc>] kthread+0x12c/0x150
 [<ffffffff81f9ccef>] ret_from_fork+0x3f/0x70

Reported-by: Zhang Yanmin <yanmin.zhang@intel.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-01-29 18:30:56 -05:00

978 lines
24 KiB
C

/*
* 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.
*
*/
#include <linux/module.h>
#include <linux/stddef.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 <linux/can/skb.h>
#include <linux/ratelimit.h>
#include <net/net_namespace.h>
#include <net/sock.h>
#include "af_can.h"
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)");
/* receive filters subscribed for 'all' CAN devices */
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 const struct can_proto *proto_tab[CAN_NPROTO] __read_mostly;
static DEFINE_MUTEX(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 */
static atomic_t skbcounter = ATOMIC_INIT(0);
/*
* af_can socket functions
*/
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;
}
}
EXPORT_SYMBOL(can_ioctl);
static void can_sock_destruct(struct sock *sk)
{
skb_queue_purge(&sk->sk_receive_queue);
}
static const struct can_proto *can_get_proto(int protocol)
{
const struct can_proto *cp;
rcu_read_lock();
cp = rcu_dereference(proto_tab[protocol]);
if (cp && !try_module_get(cp->prot->owner))
cp = NULL;
rcu_read_unlock();
return cp;
}
static inline void can_put_proto(const struct can_proto *cp)
{
module_put(cp->prot->owner);
}
static int can_create(struct net *net, struct socket *sock, int protocol,
int kern)
{
struct sock *sk;
const struct can_proto *cp;
int err = 0;
sock->state = SS_UNCONNECTED;
if (protocol < 0 || protocol >= CAN_NPROTO)
return -EINVAL;
if (!net_eq(net, &init_net))
return -EAFNOSUPPORT;
cp = can_get_proto(protocol);
#ifdef CONFIG_MODULES
if (!cp) {
/* try to load protocol module if kernel is modular */
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_ratelimited(KERN_ERR "can: request_module "
"(can-proto-%d) failed.\n", protocol);
cp = can_get_proto(protocol);
}
#endif
/* check for available protocol and correct usage */
if (!cp)
return -EPROTONOSUPPORT;
if (cp->type != sock->type) {
err = -EPROTOTYPE;
goto errout;
}
sock->ops = cp->ops;
sk = sk_alloc(net, PF_CAN, GFP_KERNEL, cp->prot, kern);
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:
can_put_proto(cp);
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
* -EMSGSIZE CAN frame size is bigger than CAN interface MTU
* -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 canfd_frame *cfd = (struct canfd_frame *)skb->data;
int err = -EINVAL;
if (skb->len == CAN_MTU) {
skb->protocol = htons(ETH_P_CAN);
if (unlikely(cfd->len > CAN_MAX_DLEN))
goto inval_skb;
} else if (skb->len == CANFD_MTU) {
skb->protocol = htons(ETH_P_CANFD);
if (unlikely(cfd->len > CANFD_MAX_DLEN))
goto inval_skb;
} else
goto inval_skb;
/*
* Make sure the CAN frame can pass the selected CAN netdevice.
* As structs can_frame and canfd_frame are similar, we can provide
* CAN FD frames to legacy CAN drivers as long as the length is <= 8
*/
if (unlikely(skb->len > skb->dev->mtu && cfd->len > CAN_MAX_DLEN)) {
err = -EMSGSIZE;
goto inval_skb;
}
if (unlikely(skb->dev->type != ARPHRD_CAN)) {
err = -EPERM;
goto inval_skb;
}
if (unlikely(!(skb->dev->flags & IFF_UP))) {
err = -ENETDOWN;
goto inval_skb;
}
skb->ip_summed = CHECKSUM_UNNECESSARY;
skb_reset_mac_header(skb);
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;
}
can_skb_set_owner(newskb, 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;
inval_skb:
kfree_skb(skb);
return err;
}
EXPORT_SYMBOL(can_send);
/*
* af_can rx path
*/
static struct dev_rcv_lists *find_dev_rcv_lists(struct net_device *dev)
{
if (!dev)
return &can_rx_alldev_list;
else
return (struct dev_rcv_lists *)dev->ml_priv;
}
/**
* effhash - hash function for 29 bit CAN identifier reduction
* @can_id: 29 bit CAN identifier
*
* Description:
* To reduce the linear traversal in one linked list of _single_ EFF CAN
* frame subscriptions the 29 bit identifier is mapped to 10 bits.
* (see CAN_EFF_RCV_HASH_BITS definition)
*
* Return:
* Hash value from 0x000 - 0x3FF ( enforced by CAN_EFF_RCV_HASH_BITS mask )
*/
static unsigned int effhash(canid_t can_id)
{
unsigned int hash;
hash = can_id;
hash ^= can_id >> CAN_EFF_RCV_HASH_BITS;
hash ^= can_id >> (2 * CAN_EFF_RCV_HASH_BITS);
return hash & ((1 << CAN_EFF_RCV_HASH_BITS) - 1);
}
/**
* 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 messages (CAN_ERR_FLAG bit set in mask). For error msg
* 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 message 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))
return &d->rx_eff[effhash(*can_id)];
} 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 identification
* @sk: socket pointer (might be NULL)
*
* 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 message 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 sock *sk)
{
struct receiver *r;
struct hlist_head *rl;
struct dev_rcv_lists *d;
int err = 0;
/* insert new receiver (dev,canid,mask) -> (func,data) */
if (dev && dev->type != ARPHRD_CAN)
return -ENODEV;
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;
r->sk = sk;
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_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);
struct sock *sk = r->sk;
kmem_cache_free(rcv_cache, r);
if (sk)
sock_put(sk);
}
/**
* can_rx_unregister - unsubscribe CAN frames from a specific interface
* @dev: pointer to netdevice (NULL => unsubscribe 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 dev_rcv_lists *d;
if (dev && dev->type != ARPHRD_CAN)
return;
spin_lock(&can_rcvlists_lock);
d = find_dev_rcv_lists(dev);
if (!d) {
pr_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, 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 using af_can.c:
* 'r' will be NULL if no matching list item was found for removal.
*/
if (!r) {
WARN(1, "BUG: receive list entry not found for dev %s, "
"id %03X, mask %03X\n", DNAME(dev), can_id, mask);
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) {
kfree(d);
dev->ml_priv = NULL;
}
out:
spin_unlock(&can_rcvlists_lock);
/* schedule the receiver item for deletion */
if (r) {
if (r->sk)
sock_hold(r->sk);
call_rcu(&r->rcu, can_rx_delete_receiver);
}
}
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;
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 message frame entries only */
hlist_for_each_entry_rcu(r, &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, &d->rx[RX_ALL], list) {
deliver(skb, r);
matches++;
}
/* check for can_id/mask entries */
hlist_for_each_entry_rcu(r, &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, &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, &d->rx_eff[effhash(can_id)], list) {
if (r->can_id == can_id) {
deliver(skb, r);
matches++;
}
}
} else {
can_id &= CAN_SFF_MASK;
hlist_for_each_entry_rcu(r, &d->rx_sff[can_id], list) {
deliver(skb, r);
matches++;
}
}
return matches;
}
static void can_receive(struct sk_buff *skb, struct net_device *dev)
{
struct dev_rcv_lists *d;
int matches;
/* update statistics */
can_stats.rx_frames++;
can_stats.rx_frames_delta++;
/* create non-zero unique skb identifier together with *skb */
while (!(can_skb_prv(skb)->skbcnt))
can_skb_prv(skb)->skbcnt = atomic_inc_return(&skbcounter);
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++;
}
}
static int can_rcv(struct sk_buff *skb, struct net_device *dev,
struct packet_type *pt, struct net_device *orig_dev)
{
struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
if (unlikely(!net_eq(dev_net(dev), &init_net)))
goto drop;
if (WARN_ONCE(dev->type != ARPHRD_CAN ||
skb->len != CAN_MTU ||
cfd->len > CAN_MAX_DLEN,
"PF_CAN: dropped non conform CAN skbuf: "
"dev type %d, len %d, datalen %d\n",
dev->type, skb->len, cfd->len))
goto drop;
can_receive(skb, dev);
return NET_RX_SUCCESS;
drop:
kfree_skb(skb);
return NET_RX_DROP;
}
static int canfd_rcv(struct sk_buff *skb, struct net_device *dev,
struct packet_type *pt, struct net_device *orig_dev)
{
struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
if (unlikely(!net_eq(dev_net(dev), &init_net)))
goto drop;
if (WARN_ONCE(dev->type != ARPHRD_CAN ||
skb->len != CANFD_MTU ||
cfd->len > CANFD_MAX_DLEN,
"PF_CAN: dropped non conform CAN FD skbuf: "
"dev type %d, len %d, datalen %d\n",
dev->type, skb->len, cfd->len))
goto drop;
can_receive(skb, dev);
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(const struct can_proto *cp)
{
int proto = cp->protocol;
int err = 0;
if (proto < 0 || proto >= CAN_NPROTO) {
pr_err("can: protocol number %d out of range\n", proto);
return -EINVAL;
}
err = proto_register(cp->prot, 0);
if (err < 0)
return err;
mutex_lock(&proto_tab_lock);
if (proto_tab[proto]) {
pr_err("can: protocol %d already registered\n", proto);
err = -EBUSY;
} else
RCU_INIT_POINTER(proto_tab[proto], cp);
mutex_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(const struct can_proto *cp)
{
int proto = cp->protocol;
mutex_lock(&proto_tab_lock);
BUG_ON(proto_tab[proto] != cp);
RCU_INIT_POINTER(proto_tab[proto], NULL);
mutex_unlock(&proto_tab_lock);
synchronize_rcu();
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 *ptr)
{
struct net_device *dev = netdev_notifier_info_to_dev(ptr);
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 */
d = kzalloc(sizeof(*d), GFP_KERNEL);
if (!d)
return NOTIFY_DONE;
BUG_ON(dev->ml_priv);
dev->ml_priv = d;
break;
case NETDEV_UNREGISTER:
spin_lock(&can_rcvlists_lock);
d = dev->ml_priv;
if (d) {
if (d->entries)
d->remove_on_zero_entries = 1;
else {
kfree(d);
dev->ml_priv = NULL;
}
} else
pr_err("can: notifier: receive list not found for dev "
"%s\n", dev->name);
spin_unlock(&can_rcvlists_lock);
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),
.func = can_rcv,
};
static struct packet_type canfd_packet __read_mostly = {
.type = cpu_to_be16(ETH_P_CANFD),
.func = canfd_rcv,
};
static const struct net_proto_family can_family_ops = {
.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)
{
/* check for correct padding to be able to use the structs similarly */
BUILD_BUG_ON(offsetof(struct can_frame, can_dlc) !=
offsetof(struct canfd_frame, len) ||
offsetof(struct can_frame, data) !=
offsetof(struct canfd_frame, data));
pr_info("can: controller area network core (" CAN_VERSION_STRING ")\n");
memset(&can_rx_alldev_list, 0, sizeof(can_rx_alldev_list));
rcv_cache = kmem_cache_create("can_receiver", sizeof(struct receiver),
0, 0, NULL);
if (!rcv_cache)
return -ENOMEM;
if (IS_ENABLED(CONFIG_PROC_FS)) {
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));
}
can_init_proc();
}
/* protocol register */
sock_register(&can_family_ops);
register_netdevice_notifier(&can_netdev_notifier);
dev_add_pack(&can_packet);
dev_add_pack(&canfd_packet);
return 0;
}
static __exit void can_exit(void)
{
struct net_device *dev;
if (IS_ENABLED(CONFIG_PROC_FS)) {
if (stats_timer)
del_timer_sync(&can_stattimer);
can_remove_proc();
}
/* protocol unregister */
dev_remove_pack(&canfd_packet);
dev_remove_pack(&can_packet);
unregister_netdevice_notifier(&can_netdev_notifier);
sock_unregister(PF_CAN);
/* remove created dev_rcv_lists from still registered CAN devices */
rcu_read_lock();
for_each_netdev_rcu(&init_net, dev) {
if (dev->type == ARPHRD_CAN && dev->ml_priv) {
struct dev_rcv_lists *d = dev->ml_priv;
BUG_ON(d->entries);
kfree(d);
dev->ml_priv = NULL;
}
}
rcu_read_unlock();
rcu_barrier(); /* Wait for completion of call_rcu()'s */
kmem_cache_destroy(rcv_cache);
}
module_init(can_init);
module_exit(can_exit);