/*
 * raw.c - Raw sockets for protocol family CAN
 *
 * 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/init.h>
#include <linux/uio.h>
#include <linux/net.h>
#include <linux/slab.h>
#include <linux/netdevice.h>
#include <linux/socket.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/can/raw.h>
#include <net/sock.h>
#include <net/net_namespace.h>

#define CAN_RAW_VERSION CAN_VERSION
static __initconst const char banner[] =
        KERN_INFO "can: raw protocol (rev " CAN_RAW_VERSION ")\n";

MODULE_DESCRIPTION("PF_CAN raw protocol");
MODULE_LICENSE("Dual BSD/GPL");
MODULE_AUTHOR("Urs Thuermann <urs.thuermann@volkswagen.de>");
MODULE_ALIAS("can-proto-1");

#define MASK_ALL 0

/*
 * A raw socket has a list of can_filters attached to it, each receiving
 * the CAN frames matching that filter.  If the filter list is empty,
 * no CAN frames will be received by the socket.  The default after
 * opening the socket, is to have one filter which receives all frames.
 * The filter list is allocated dynamically with the exception of the
 * list containing only one item.  This common case is optimized by
 * storing the single filter in dfilter, to avoid using dynamic memory.
 */

struct raw_sock {
        struct sock sk;
        int bound;
        int ifindex;
        struct notifier_block notifier;
        int loopback;
        int recv_own_msgs;
        int fd_frames;
        int count;                 /* number of active filters */
        struct can_filter dfilter; /* default/single filter */
        struct can_filter *filter; /* pointer to filter(s) */
        can_err_mask_t err_mask;
};

/*
 * Return pointer to store the extra msg flags for raw_recvmsg().
 * We use the space of one unsigned int beyond the 'struct sockaddr_can'
 * in skb->cb.
 */
static inline unsigned int *raw_flags(struct sk_buff *skb)
{
        BUILD_BUG_ON(sizeof(skb->cb) <= (sizeof(struct sockaddr_can) +
                                         sizeof(unsigned int)));

        /* return pointer after struct sockaddr_can */
        return (unsigned int *)(&((struct sockaddr_can *)skb->cb)[1]);
}

static inline struct raw_sock *raw_sk(const struct sock *sk)
{
        return (struct raw_sock *)sk;
}

static void raw_rcv(struct sk_buff *oskb, void *data)
{
        struct sock *sk = (struct sock *)data;
        struct raw_sock *ro = raw_sk(sk);
        struct sockaddr_can *addr;
        struct sk_buff *skb;
        unsigned int *pflags;

        /* check the received tx sock reference */
        if (!ro->recv_own_msgs && oskb->sk == sk)
                return;

        /* do not pass frames with DLC > 8 to a legacy socket */
        if (!ro->fd_frames) {
                struct canfd_frame *cfd = (struct canfd_frame *)oskb->data;

                if (unlikely(cfd->len > CAN_MAX_DLEN))
                        return;
        }

        /* clone the given skb to be able to enqueue it into the rcv queue */
        skb = skb_clone(oskb, GFP_ATOMIC);
        if (!skb)
                return;

        /*
         *  Put the datagram to the queue so that raw_recvmsg() can
         *  get it from there.  We need to pass the interface index to
         *  raw_recvmsg().  We pass a whole struct sockaddr_can in skb->cb
         *  containing the interface index.
         */

        BUILD_BUG_ON(sizeof(skb->cb) < sizeof(struct sockaddr_can));
        addr = (struct sockaddr_can *)skb->cb;
        memset(addr, 0, sizeof(*addr));
        addr->can_family  = AF_CAN;
        addr->can_ifindex = skb->dev->ifindex;

        /* add CAN specific message flags for raw_recvmsg() */
        pflags = raw_flags(skb);
        *pflags = 0;
        if (oskb->sk)
                *pflags |= MSG_DONTROUTE;
        if (oskb->sk == sk)
                *pflags |= MSG_CONFIRM;

        if (sock_queue_rcv_skb(sk, skb) < 0)
                kfree_skb(skb);
}

static int raw_enable_filters(struct net_device *dev, struct sock *sk,
                              struct can_filter *filter, int count)
{
        int err = 0;
        int i;

        for (i = 0; i < count; i++) {
                err = can_rx_register(dev, filter[i].can_id,
                                      filter[i].can_mask,
                                      raw_rcv, sk, "raw");
                if (err) {
                        /* clean up successfully registered filters */
                        while (--i >= 0)
                                can_rx_unregister(dev, filter[i].can_id,
                                                  filter[i].can_mask,
                                                  raw_rcv, sk);
                        break;
                }
        }

        return err;
}

static int raw_enable_errfilter(struct net_device *dev, struct sock *sk,
                                can_err_mask_t err_mask)
{
        int err = 0;

        if (err_mask)
                err = can_rx_register(dev, 0, err_mask | CAN_ERR_FLAG,
                                      raw_rcv, sk, "raw");

        return err;
}

static void raw_disable_filters(struct net_device *dev, struct sock *sk,
                              struct can_filter *filter, int count)
{
        int i;

        for (i = 0; i < count; i++)
                can_rx_unregister(dev, filter[i].can_id, filter[i].can_mask,
                                  raw_rcv, sk);
}

static inline void raw_disable_errfilter(struct net_device *dev,
                                         struct sock *sk,
                                         can_err_mask_t err_mask)

{
        if (err_mask)
                can_rx_unregister(dev, 0, err_mask | CAN_ERR_FLAG,
                                  raw_rcv, sk);
}

static inline void raw_disable_allfilters(struct net_device *dev,
                                          struct sock *sk)
{
        struct raw_sock *ro = raw_sk(sk);

        raw_disable_filters(dev, sk, ro->filter, ro->count);
        raw_disable_errfilter(dev, sk, ro->err_mask);
}

static int raw_enable_allfilters(struct net_device *dev, struct sock *sk)
{
        struct raw_sock *ro = raw_sk(sk);
        int err;

        err = raw_enable_filters(dev, sk, ro->filter, ro->count);
        if (!err) {
                err = raw_enable_errfilter(dev, sk, ro->err_mask);
                if (err)
                        raw_disable_filters(dev, sk, ro->filter, ro->count);
        }

        return err;
}

static int raw_notifier(struct notifier_block *nb,
                        unsigned long msg, void *ptr)
{
        struct net_device *dev = netdev_notifier_info_to_dev(ptr);
        struct raw_sock *ro = container_of(nb, struct raw_sock, notifier);
        struct sock *sk = &ro->sk;

        if (!net_eq(dev_net(dev), &init_net))
                return NOTIFY_DONE;

        if (dev->type != ARPHRD_CAN)
                return NOTIFY_DONE;

        if (ro->ifindex != dev->ifindex)
                return NOTIFY_DONE;

        switch (msg) {

        case NETDEV_UNREGISTER:
                lock_sock(sk);
                /* remove current filters & unregister */
                if (ro->bound)
                        raw_disable_allfilters(dev, sk);

                if (ro->count > 1)
                        kfree(ro->filter);

                ro->ifindex = 0;
                ro->bound   = 0;
                ro->count   = 0;
                release_sock(sk);

                sk->sk_err = ENODEV;
                if (!sock_flag(sk, SOCK_DEAD))
                        sk->sk_error_report(sk);
                break;

        case NETDEV_DOWN:
                sk->sk_err = ENETDOWN;
                if (!sock_flag(sk, SOCK_DEAD))
                        sk->sk_error_report(sk);
                break;
        }

        return NOTIFY_DONE;
}

static int raw_init(struct sock *sk)
{
        struct raw_sock *ro = raw_sk(sk);

        ro->bound            = 0;
        ro->ifindex          = 0;

        /* set default filter to single entry dfilter */
        ro->dfilter.can_id   = 0;
        ro->dfilter.can_mask = MASK_ALL;
        ro->filter           = &ro->dfilter;
        ro->count            = 1;

        /* set default loopback behaviour */
        ro->loopback         = 1;
        ro->recv_own_msgs    = 0;
        ro->fd_frames        = 0;

        /* set notifier */
        ro->notifier.notifier_call = raw_notifier;

        register_netdevice_notifier(&ro->notifier);

        return 0;
}

static int raw_release(struct socket *sock)
{
        struct sock *sk = sock->sk;
        struct raw_sock *ro;

        if (!sk)
                return 0;

        ro = raw_sk(sk);

        unregister_netdevice_notifier(&ro->notifier);

        lock_sock(sk);

        /* remove current filters & unregister */
        if (ro->bound) {
                if (ro->ifindex) {
                        struct net_device *dev;

                        dev = dev_get_by_index(&init_net, ro->ifindex);
                        if (dev) {
                                raw_disable_allfilters(dev, sk);
                                dev_put(dev);
                        }
                } else
                        raw_disable_allfilters(NULL, sk);
        }

        if (ro->count > 1)
                kfree(ro->filter);

        ro->ifindex = 0;
        ro->bound   = 0;
        ro->count   = 0;

        sock_orphan(sk);
        sock->sk = NULL;

        release_sock(sk);
        sock_put(sk);

        return 0;
}

static int raw_bind(struct socket *sock, struct sockaddr *uaddr, int len)
{
        struct sockaddr_can *addr = (struct sockaddr_can *)uaddr;
        struct sock *sk = sock->sk;
        struct raw_sock *ro = raw_sk(sk);
        int ifindex;
        int err = 0;
        int notify_enetdown = 0;

        if (len < sizeof(*addr))
                return -EINVAL;

        lock_sock(sk);

        if (ro->bound && addr->can_ifindex == ro->ifindex)
                goto out;

        if (addr->can_ifindex) {
                struct net_device *dev;

                dev = dev_get_by_index(&init_net, addr->can_ifindex);
                if (!dev) {
                        err = -ENODEV;
                        goto out;
                }
                if (dev->type != ARPHRD_CAN) {
                        dev_put(dev);
                        err = -ENODEV;
                        goto out;
                }
                if (!(dev->flags & IFF_UP))
                        notify_enetdown = 1;

                ifindex = dev->ifindex;

                /* filters set by default/setsockopt */
                err = raw_enable_allfilters(dev, sk);
                dev_put(dev);
        } else {
                ifindex = 0;

                /* filters set by default/setsockopt */
                err = raw_enable_allfilters(NULL, sk);
        }

        if (!err) {
                if (ro->bound) {
                        /* unregister old filters */
                        if (ro->ifindex) {
                                struct net_device *dev;

                                dev = dev_get_by_index(&init_net, ro->ifindex);
                                if (dev) {
                                        raw_disable_allfilters(dev, sk);
                                        dev_put(dev);
                                }
                        } else
                                raw_disable_allfilters(NULL, sk);
                }
                ro->ifindex = ifindex;
                ro->bound = 1;
        }

 out:
        release_sock(sk);

        if (notify_enetdown) {
                sk->sk_err = ENETDOWN;
                if (!sock_flag(sk, SOCK_DEAD))
                        sk->sk_error_report(sk);
        }

        return err;
}

static int raw_getname(struct socket *sock, struct sockaddr *uaddr,
                       int *len, int peer)
{
        struct sockaddr_can *addr = (struct sockaddr_can *)uaddr;
        struct sock *sk = sock->sk;
        struct raw_sock *ro = raw_sk(sk);

        if (peer)
                return -EOPNOTSUPP;

        memset(addr, 0, sizeof(*addr));
        addr->can_family  = AF_CAN;
        addr->can_ifindex = ro->ifindex;

        *len = sizeof(*addr);

        return 0;
}

static int raw_setsockopt(struct socket *sock, int level, int optname,
                          char __user *optval, unsigned int optlen)
{
        struct sock *sk = sock->sk;
        struct raw_sock *ro = raw_sk(sk);
        struct can_filter *filter = NULL;  /* dyn. alloc'ed filters */
        struct can_filter sfilter;         /* single filter */
        struct net_device *dev = NULL;
        can_err_mask_t err_mask = 0;
        int count = 0;
        int err = 0;

        if (level != SOL_CAN_RAW)
                return -EINVAL;

        switch (optname) {

        case CAN_RAW_FILTER:
                if (optlen % sizeof(struct can_filter) != 0)
                        return -EINVAL;

                count = optlen / sizeof(struct can_filter);

                if (count > 1) {
                        /* filter does not fit into dfilter => alloc space */
                        filter = memdup_user(optval, optlen);
                        if (IS_ERR(filter))
                                return PTR_ERR(filter);
                } else if (count == 1) {
                        if (copy_from_user(&sfilter, optval, sizeof(sfilter)))
                                return -EFAULT;
                }

                lock_sock(sk);

                if (ro->bound && ro->ifindex)
                        dev = dev_get_by_index(&init_net, ro->ifindex);

                if (ro->bound) {
                        /* (try to) register the new filters */
                        if (count == 1)
                                err = raw_enable_filters(dev, sk, &sfilter, 1);
                        else
                                err = raw_enable_filters(dev, sk, filter,
                                                         count);
                        if (err) {
                                if (count > 1)
                                        kfree(filter);
                                goto out_fil;
                        }

                        /* remove old filter registrations */
                        raw_disable_filters(dev, sk, ro->filter, ro->count);
                }

                /* remove old filter space */
                if (ro->count > 1)
                        kfree(ro->filter);

                /* link new filters to the socket */
                if (count == 1) {
                        /* copy filter data for single filter */
                        ro->dfilter = sfilter;
                        filter = &ro->dfilter;
                }
                ro->filter = filter;
                ro->count  = count;

 out_fil:
                if (dev)
                        dev_put(dev);

                release_sock(sk);

                break;

        case CAN_RAW_ERR_FILTER:
                if (optlen != sizeof(err_mask))
                        return -EINVAL;

                if (copy_from_user(&err_mask, optval, optlen))
                        return -EFAULT;

                err_mask &= CAN_ERR_MASK;

                lock_sock(sk);

                if (ro->bound && ro->ifindex)
                        dev = dev_get_by_index(&init_net, ro->ifindex);

                /* remove current error mask */
                if (ro->bound) {
                        /* (try to) register the new err_mask */
                        err = raw_enable_errfilter(dev, sk, err_mask);

                        if (err)
                                goto out_err;

                        /* remove old err_mask registration */
                        raw_disable_errfilter(dev, sk, ro->err_mask);
                }

                /* link new err_mask to the socket */
                ro->err_mask = err_mask;

 out_err:
                if (dev)
                        dev_put(dev);

                release_sock(sk);

                break;

        case CAN_RAW_LOOPBACK:
                if (optlen != sizeof(ro->loopback))
                        return -EINVAL;

                if (copy_from_user(&ro->loopback, optval, optlen))
                        return -EFAULT;

                break;

        case CAN_RAW_RECV_OWN_MSGS:
                if (optlen != sizeof(ro->recv_own_msgs))
                        return -EINVAL;

                if (copy_from_user(&ro->recv_own_msgs, optval, optlen))
                        return -EFAULT;

                break;

        case CAN_RAW_FD_FRAMES:
                if (optlen != sizeof(ro->fd_frames))
                        return -EINVAL;

                if (copy_from_user(&ro->fd_frames, optval, optlen))
                        return -EFAULT;

                break;

        default:
                return -ENOPROTOOPT;
        }
        return err;
}

static int raw_getsockopt(struct socket *sock, int level, int optname,
                          char __user *optval, int __user *optlen)
{
        struct sock *sk = sock->sk;
        struct raw_sock *ro = raw_sk(sk);
        int len;
        void *val;
        int err = 0;

        if (level != SOL_CAN_RAW)
                return -EINVAL;
        if (get_user(len, optlen))
                return -EFAULT;
        if (len < 0)
                return -EINVAL;

        switch (optname) {

        case CAN_RAW_FILTER:
                lock_sock(sk);
                if (ro->count > 0) {
                        int fsize = ro->count * sizeof(struct can_filter);
                        if (len > fsize)
                                len = fsize;
                        if (copy_to_user(optval, ro->filter, len))
                                err = -EFAULT;
                } else
                        len = 0;
                release_sock(sk);

                if (!err)
                        err = put_user(len, optlen);
                return err;

        case CAN_RAW_ERR_FILTER:
                if (len > sizeof(can_err_mask_t))
                        len = sizeof(can_err_mask_t);
                val = &ro->err_mask;
                break;

        case CAN_RAW_LOOPBACK:
                if (len > sizeof(int))
                        len = sizeof(int);
                val = &ro->loopback;
                break;

        case CAN_RAW_RECV_OWN_MSGS:
                if (len > sizeof(int))
                        len = sizeof(int);
                val = &ro->recv_own_msgs;
                break;

        case CAN_RAW_FD_FRAMES:
                if (len > sizeof(int))
                        len = sizeof(int);
                val = &ro->fd_frames;
                break;

        default:
                return -ENOPROTOOPT;
        }

        if (put_user(len, optlen))
                return -EFAULT;
        if (copy_to_user(optval, val, len))
                return -EFAULT;
        return 0;
}

static int raw_sendmsg(struct kiocb *iocb, struct socket *sock,
                       struct msghdr *msg, size_t size)
{
        struct sock *sk = sock->sk;
        struct raw_sock *ro = raw_sk(sk);
        struct sk_buff *skb;
        struct net_device *dev;
        int ifindex;
        int err;

        if (msg->msg_name) {
                struct sockaddr_can *addr =
                        (struct sockaddr_can *)msg->msg_name;

                if (msg->msg_namelen < sizeof(*addr))
                        return -EINVAL;

                if (addr->can_family != AF_CAN)
                        return -EINVAL;

                ifindex = addr->can_ifindex;
        } else
                ifindex = ro->ifindex;

        if (ro->fd_frames) {
                if (unlikely(size != CANFD_MTU && size != CAN_MTU))
                        return -EINVAL;
        } else {
                if (unlikely(size != CAN_MTU))
                        return -EINVAL;
        }

        dev = dev_get_by_index(&init_net, ifindex);
        if (!dev)
                return -ENXIO;

        skb = sock_alloc_send_skb(sk, size + sizeof(struct can_skb_priv),
                                  msg->msg_flags & MSG_DONTWAIT, &err);
        if (!skb)
                goto put_dev;

        can_skb_reserve(skb);
        can_skb_prv(skb)->ifindex = dev->ifindex;

        err = memcpy_fromiovec(skb_put(skb, size), msg->msg_iov, size);
        if (err < 0)
                goto free_skb;

        sock_tx_timestamp(sk, &skb_shinfo(skb)->tx_flags);

        skb->dev = dev;
        skb->sk  = sk;

        err = can_send(skb, ro->loopback);

        dev_put(dev);

        if (err)
                goto send_failed;

        return size;

free_skb:
        kfree_skb(skb);
put_dev:
        dev_put(dev);
send_failed:
        return err;
}

static int raw_recvmsg(struct kiocb *iocb, struct socket *sock,
                       struct msghdr *msg, size_t size, int flags)
{
        struct sock *sk = sock->sk;
        struct raw_sock *ro = raw_sk(sk);
        struct sk_buff *skb;
        int rxmtu;
        int err = 0;
        int noblock;

        noblock =  flags & MSG_DONTWAIT;
        flags   &= ~MSG_DONTWAIT;

        skb = skb_recv_datagram(sk, flags, noblock, &err);
        if (!skb)
                return err;

        /*
         * when serving a legacy socket the DLC <= 8 is already checked inside
         * raw_rcv(). Now check if we need to pass a canfd_frame to a legacy
         * socket and cut the possible CANFD_MTU/CAN_MTU length to CAN_MTU
         */
        if (!ro->fd_frames)
                rxmtu = CAN_MTU;
        else
                rxmtu = skb->len;

        if (size < rxmtu)
                msg->msg_flags |= MSG_TRUNC;
        else
                size = rxmtu;

        err = memcpy_toiovec(msg->msg_iov, skb->data, size);
        if (err < 0) {
                skb_free_datagram(sk, skb);
                return err;
        }

        sock_recv_ts_and_drops(msg, sk, skb);

        if (msg->msg_name) {
                msg->msg_namelen = sizeof(struct sockaddr_can);
                memcpy(msg->msg_name, skb->cb, msg->msg_namelen);
        }

        /* assign the flags that have been recorded in raw_rcv() */
        msg->msg_flags |= *(raw_flags(skb));

        skb_free_datagram(sk, skb);

        return size;
}

static const struct proto_ops raw_ops = {
        .family        = PF_CAN,
        .release       = raw_release,
        .bind          = raw_bind,
        .connect       = sock_no_connect,
        .socketpair    = sock_no_socketpair,
        .accept        = sock_no_accept,
        .getname       = raw_getname,
        .poll          = datagram_poll,
        .ioctl         = can_ioctl,     /* use can_ioctl() from af_can.c */
        .listen        = sock_no_listen,
        .shutdown      = sock_no_shutdown,
        .setsockopt    = raw_setsockopt,
        .getsockopt    = raw_getsockopt,
        .sendmsg       = raw_sendmsg,
        .recvmsg       = raw_recvmsg,
        .mmap          = sock_no_mmap,
        .sendpage      = sock_no_sendpage,
};

static struct proto raw_proto __read_mostly = {
        .name       = "CAN_RAW",
        .owner      = THIS_MODULE,
        .obj_size   = sizeof(struct raw_sock),
        .init       = raw_init,
};

static const struct can_proto raw_can_proto = {
        .type       = SOCK_RAW,
        .protocol   = CAN_RAW,
        .ops        = &raw_ops,
        .prot       = &raw_proto,
};

static __init int raw_module_init(void)
{
        int err;

        printk(banner);

        err = can_proto_register(&raw_can_proto);
        if (err < 0)
                printk(KERN_ERR "can: registration of raw protocol failed\n");

        return err;
}

static __exit void raw_module_exit(void)
{
        can_proto_unregister(&raw_can_proto);
}

module_init(raw_module_init);
module_exit(raw_module_exit);