// SPDX-License-Identifier: GPL-2.0-only
/*
 * File: socket.c
 *
 * Phonet sockets
 *
 * Copyright (C) 2008 Nokia Corporation.
 *
 * Authors: Sakari Ailus <sakari.ailus@nokia.com>
 *          Rémi Denis-Courmont
 */

#include <linux/gfp.h>
#include <linux/kernel.h>
#include <linux/net.h>
#include <linux/poll.h>
#include <linux/sched/signal.h>

#include <net/sock.h>
#include <net/tcp_states.h>

#include <linux/phonet.h>
#include <linux/export.h>
#include <net/phonet/phonet.h>
#include <net/phonet/pep.h>
#include <net/phonet/pn_dev.h>

static int pn_socket_release(struct socket *sock)
{
        struct sock *sk = sock->sk;

        if (sk) {
                sock->sk = NULL;
                sk->sk_prot->close(sk, 0);
        }
        return 0;
}

#define PN_HASHSIZE     16
#define PN_HASHMASK     (PN_HASHSIZE-1)


static struct  {
        struct hlist_head hlist[PN_HASHSIZE];
        struct mutex lock;
} pnsocks;

void __init pn_sock_init(void)
{
        unsigned int i;

        for (i = 0; i < PN_HASHSIZE; i++)
                INIT_HLIST_HEAD(pnsocks.hlist + i);
        mutex_init(&pnsocks.lock);
}

static struct hlist_head *pn_hash_list(u16 obj)
{
        return pnsocks.hlist + (obj & PN_HASHMASK);
}

/*
 * Find address based on socket address, match only certain fields.
 * Also grab sock if it was found. Remember to sock_put it later.
 */
struct sock *pn_find_sock_by_sa(struct net *net, const struct sockaddr_pn *spn)
{
        struct sock *sknode;
        struct sock *rval = NULL;
        u16 obj = pn_sockaddr_get_object(spn);
        u8 res = spn->spn_resource;
        struct hlist_head *hlist = pn_hash_list(obj);

        rcu_read_lock();
        sk_for_each_rcu(sknode, hlist) {
                struct pn_sock *pn = pn_sk(sknode);
                BUG_ON(!pn->sobject); /* unbound socket */

                if (!net_eq(sock_net(sknode), net))
                        continue;
                if (pn_port(obj)) {
                        /* Look up socket by port */
                        if (pn_port(pn->sobject) != pn_port(obj))
                                continue;
                } else {
                        /* If port is zero, look up by resource */
                        if (pn->resource != res)
                                continue;
                }
                if (pn_addr(pn->sobject) &&
                    pn_addr(pn->sobject) != pn_addr(obj))
                        continue;

                rval = sknode;
                sock_hold(sknode);
                break;
        }
        rcu_read_unlock();

        return rval;
}

/* Deliver a broadcast packet (only in bottom-half) */
void pn_deliver_sock_broadcast(struct net *net, struct sk_buff *skb)
{
        struct hlist_head *hlist = pnsocks.hlist;
        unsigned int h;

        rcu_read_lock();
        for (h = 0; h < PN_HASHSIZE; h++) {
                struct sock *sknode;

                sk_for_each(sknode, hlist) {
                        struct sk_buff *clone;

                        if (!net_eq(sock_net(sknode), net))
                                continue;
                        if (!sock_flag(sknode, SOCK_BROADCAST))
                                continue;

                        clone = skb_clone(skb, GFP_ATOMIC);
                        if (clone) {
                                sock_hold(sknode);
                                sk_receive_skb(sknode, clone, 0);
                        }
                }
                hlist++;
        }
        rcu_read_unlock();
}

int pn_sock_hash(struct sock *sk)
{
        struct hlist_head *hlist = pn_hash_list(pn_sk(sk)->sobject);

        mutex_lock(&pnsocks.lock);
        sk_add_node_rcu(sk, hlist);
        mutex_unlock(&pnsocks.lock);

        return 0;
}
EXPORT_SYMBOL(pn_sock_hash);

void pn_sock_unhash(struct sock *sk)
{
        mutex_lock(&pnsocks.lock);
        sk_del_node_init_rcu(sk);
        mutex_unlock(&pnsocks.lock);
        pn_sock_unbind_all_res(sk);
        synchronize_rcu();
}
EXPORT_SYMBOL(pn_sock_unhash);

static DEFINE_MUTEX(port_mutex);

static int pn_socket_bind(struct socket *sock, struct sockaddr_unsized *addr, int len)
{
        struct sock *sk = sock->sk;
        struct pn_sock *pn = pn_sk(sk);
        struct sockaddr_pn *spn = (struct sockaddr_pn *)addr;
        int err;
        u16 handle;
        u8 saddr;

        if (sk->sk_prot->bind)
                return sk->sk_prot->bind(sk, addr, len);

        if (len < sizeof(struct sockaddr_pn))
                return -EINVAL;
        if (spn->spn_family != AF_PHONET)
                return -EAFNOSUPPORT;

        handle = pn_sockaddr_get_object((struct sockaddr_pn *)addr);
        saddr = pn_addr(handle);
        if (saddr && phonet_address_lookup(sock_net(sk), saddr))
                return -EADDRNOTAVAIL;

        lock_sock(sk);
        if (sk->sk_state != TCP_CLOSE || pn_port(pn->sobject)) {
                err = -EINVAL; /* attempt to rebind */
                goto out;
        }
        WARN_ON(sk_hashed(sk));
        mutex_lock(&port_mutex);
        err = sk->sk_prot->get_port(sk, pn_port(handle));
        if (err)
                goto out_port;

        /* get_port() sets the port, bind() sets the address if applicable */
        pn->sobject = pn_object(saddr, pn_port(pn->sobject));
        pn->resource = spn->spn_resource;

        /* Enable RX on the socket */
        err = sk->sk_prot->hash(sk);
out_port:
        mutex_unlock(&port_mutex);
out:
        release_sock(sk);
        return err;
}

static int pn_socket_autobind(struct socket *sock)
{
        struct sockaddr_pn sa;
        int err;

        memset(&sa, 0, sizeof(sa));
        sa.spn_family = AF_PHONET;
        err = pn_socket_bind(sock, (struct sockaddr_unsized *)&sa,
                             sizeof(struct sockaddr_pn));
        if (err != -EINVAL)
                return err;
        BUG_ON(!pn_port(pn_sk(sock->sk)->sobject));
        return 0; /* socket was already bound */
}

static int pn_socket_connect(struct socket *sock, struct sockaddr_unsized *addr,
                             int len, int flags)
{
        struct sock *sk = sock->sk;
        struct pn_sock *pn = pn_sk(sk);
        struct sockaddr_pn *spn = (struct sockaddr_pn *)addr;
        struct task_struct *tsk = current;
        long timeo = sock_rcvtimeo(sk, flags & O_NONBLOCK);
        int err;

        if (pn_socket_autobind(sock))
                return -ENOBUFS;
        if (len < sizeof(struct sockaddr_pn))
                return -EINVAL;
        if (spn->spn_family != AF_PHONET)
                return -EAFNOSUPPORT;

        lock_sock(sk);

        switch (sock->state) {
        case SS_UNCONNECTED:
                if (sk->sk_state != TCP_CLOSE) {
                        err = -EISCONN;
                        goto out;
                }
                break;
        case SS_CONNECTING:
                err = -EALREADY;
                goto out;
        default:
                err = -EISCONN;
                goto out;
        }

        pn->dobject = pn_sockaddr_get_object(spn);
        pn->resource = pn_sockaddr_get_resource(spn);
        sock->state = SS_CONNECTING;

        err = sk->sk_prot->connect(sk, addr, len);
        if (err) {
                sock->state = SS_UNCONNECTED;
                pn->dobject = 0;
                goto out;
        }

        while (sk->sk_state == TCP_SYN_SENT) {
                DEFINE_WAIT(wait);

                if (!timeo) {
                        err = -EINPROGRESS;
                        goto out;
                }
                if (signal_pending(tsk)) {
                        err = sock_intr_errno(timeo);
                        goto out;
                }

                prepare_to_wait_exclusive(sk_sleep(sk), &wait,
                                                TASK_INTERRUPTIBLE);
                release_sock(sk);
                timeo = schedule_timeout(timeo);
                lock_sock(sk);
                finish_wait(sk_sleep(sk), &wait);
        }

        if ((1 << sk->sk_state) & (TCPF_SYN_RECV|TCPF_ESTABLISHED))
                err = 0;
        else if (sk->sk_state == TCP_CLOSE_WAIT)
                err = -ECONNRESET;
        else
                err = -ECONNREFUSED;
        sock->state = err ? SS_UNCONNECTED : SS_CONNECTED;
out:
        release_sock(sk);
        return err;
}

static int pn_socket_accept(struct socket *sock, struct socket *newsock,
                            struct proto_accept_arg *arg)
{
        struct sock *sk = sock->sk;
        struct sock *newsk;

        if (unlikely(sk->sk_state != TCP_LISTEN))
                return -EINVAL;

        newsk = sk->sk_prot->accept(sk, arg);
        if (!newsk)
                return arg->err;

        lock_sock(newsk);
        sock_graft(newsk, newsock);
        newsock->state = SS_CONNECTED;
        release_sock(newsk);
        return 0;
}

static int pn_socket_getname(struct socket *sock, struct sockaddr *addr,
                                int peer)
{
        struct sock *sk = sock->sk;
        struct pn_sock *pn = pn_sk(sk);

        memset(addr, 0, sizeof(struct sockaddr_pn));
        addr->sa_family = AF_PHONET;
        if (!peer) /* Race with bind() here is userland's problem. */
                pn_sockaddr_set_object((struct sockaddr_pn *)addr,
                                        pn->sobject);

        return sizeof(struct sockaddr_pn);
}

static __poll_t pn_socket_poll(struct file *file, struct socket *sock,
                                        poll_table *wait)
{
        struct sock *sk = sock->sk;
        struct pep_sock *pn = pep_sk(sk);
        __poll_t mask = 0;

        poll_wait(file, sk_sleep(sk), wait);

        if (sk->sk_state == TCP_CLOSE)
                return EPOLLERR;
        if (!skb_queue_empty_lockless(&sk->sk_receive_queue))
                mask |= EPOLLIN | EPOLLRDNORM;
        if (!skb_queue_empty_lockless(&pn->ctrlreq_queue))
                mask |= EPOLLPRI;
        if (!mask && sk->sk_state == TCP_CLOSE_WAIT)
                return EPOLLHUP;

        if (sk->sk_state == TCP_ESTABLISHED &&
                refcount_read(&sk->sk_wmem_alloc) < sk->sk_sndbuf &&
                atomic_read(&pn->tx_credits))
                mask |= EPOLLOUT | EPOLLWRNORM | EPOLLWRBAND;

        return mask;
}

static int pn_socket_ioctl(struct socket *sock, unsigned int cmd,
                                unsigned long arg)
{
        struct sock *sk = sock->sk;
        struct pn_sock *pn = pn_sk(sk);

        if (cmd == SIOCPNGETOBJECT) {
                struct net_device *dev;
                u16 handle;
                u8 saddr;

                if (get_user(handle, (__u16 __user *)arg))
                        return -EFAULT;

                lock_sock(sk);
                if (sk->sk_bound_dev_if)
                        dev = dev_get_by_index(sock_net(sk),
                                                sk->sk_bound_dev_if);
                else
                        dev = phonet_device_get(sock_net(sk));
                if (dev && (dev->flags & IFF_UP))
                        saddr = phonet_address_get(dev, pn_addr(handle));
                else
                        saddr = PN_NO_ADDR;
                release_sock(sk);

                dev_put(dev);
                if (saddr == PN_NO_ADDR)
                        return -EHOSTUNREACH;

                handle = pn_object(saddr, pn_port(pn->sobject));
                return put_user(handle, (__u16 __user *)arg);
        }

        return sk_ioctl(sk, cmd, (void __user *)arg);
}

static int pn_socket_listen(struct socket *sock, int backlog)
{
        struct sock *sk = sock->sk;
        int err = 0;

        if (pn_socket_autobind(sock))
                return -ENOBUFS;

        lock_sock(sk);
        if (sock->state != SS_UNCONNECTED) {
                err = -EINVAL;
                goto out;
        }

        if (sk->sk_state != TCP_LISTEN) {
                sk->sk_state = TCP_LISTEN;
                sk->sk_ack_backlog = 0;
        }
        sk->sk_max_ack_backlog = backlog;
out:
        release_sock(sk);
        return err;
}

static int pn_socket_sendmsg(struct socket *sock, struct msghdr *m,
                             size_t total_len)
{
        struct sock *sk = sock->sk;

        if (pn_socket_autobind(sock))
                return -EAGAIN;

        return sk->sk_prot->sendmsg(sk, m, total_len);
}

const struct proto_ops phonet_dgram_ops = {
        .family         = AF_PHONET,
        .owner          = THIS_MODULE,
        .release        = pn_socket_release,
        .bind           = pn_socket_bind,
        .connect        = sock_no_connect,
        .socketpair     = sock_no_socketpair,
        .accept         = sock_no_accept,
        .getname        = pn_socket_getname,
        .poll           = datagram_poll,
        .ioctl          = pn_socket_ioctl,
        .listen         = sock_no_listen,
        .shutdown       = sock_no_shutdown,
        .sendmsg        = pn_socket_sendmsg,
        .recvmsg        = sock_common_recvmsg,
        .mmap           = sock_no_mmap,
};

const struct proto_ops phonet_stream_ops = {
        .family         = AF_PHONET,
        .owner          = THIS_MODULE,
        .release        = pn_socket_release,
        .bind           = pn_socket_bind,
        .connect        = pn_socket_connect,
        .socketpair     = sock_no_socketpair,
        .accept         = pn_socket_accept,
        .getname        = pn_socket_getname,
        .poll           = pn_socket_poll,
        .ioctl          = pn_socket_ioctl,
        .listen         = pn_socket_listen,
        .shutdown       = sock_no_shutdown,
        .setsockopt     = sock_common_setsockopt,
        .getsockopt     = sock_common_getsockopt,
        .sendmsg        = pn_socket_sendmsg,
        .recvmsg        = sock_common_recvmsg,
        .mmap           = sock_no_mmap,
};
EXPORT_SYMBOL(phonet_stream_ops);

/* allocate port for a socket */
int pn_sock_get_port(struct sock *sk, unsigned short sport)
{
        static int port_cur;
        struct net *net = sock_net(sk);
        struct pn_sock *pn = pn_sk(sk);
        struct sockaddr_pn try_sa;
        struct sock *tmpsk;

        memset(&try_sa, 0, sizeof(struct sockaddr_pn));
        try_sa.spn_family = AF_PHONET;
        WARN_ON(!mutex_is_locked(&port_mutex));
        if (!sport) {
                /* search free port */
                int port, pmin, pmax;

                phonet_get_local_port_range(&pmin, &pmax);
                for (port = pmin; port <= pmax; port++) {
                        port_cur++;
                        if (port_cur < pmin || port_cur > pmax)
                                port_cur = pmin;

                        pn_sockaddr_set_port(&try_sa, port_cur);
                        tmpsk = pn_find_sock_by_sa(net, &try_sa);
                        if (tmpsk == NULL) {
                                sport = port_cur;
                                goto found;
                        } else
                                sock_put(tmpsk);
                }
        } else {
                /* try to find specific port */
                pn_sockaddr_set_port(&try_sa, sport);
                tmpsk = pn_find_sock_by_sa(net, &try_sa);
                if (tmpsk == NULL)
                        /* No sock there! We can use that port... */
                        goto found;
                else
                        sock_put(tmpsk);
        }
        /* the port must be in use already */
        return -EADDRINUSE;

found:
        pn->sobject = pn_object(pn_addr(pn->sobject), sport);
        return 0;
}
EXPORT_SYMBOL(pn_sock_get_port);

#ifdef CONFIG_PROC_FS
static struct sock *pn_sock_get_idx(struct seq_file *seq, loff_t pos)
{
        struct net *net = seq_file_net(seq);
        struct hlist_head *hlist = pnsocks.hlist;
        struct sock *sknode;
        unsigned int h;

        for (h = 0; h < PN_HASHSIZE; h++) {
                sk_for_each_rcu(sknode, hlist) {
                        if (!net_eq(net, sock_net(sknode)))
                                continue;
                        if (!pos)
                                return sknode;
                        pos--;
                }
                hlist++;
        }
        return NULL;
}

static struct sock *pn_sock_get_next(struct seq_file *seq, struct sock *sk)
{
        struct net *net = seq_file_net(seq);

        do
                sk = sk_next(sk);
        while (sk && !net_eq(net, sock_net(sk)));

        return sk;
}

static void *pn_sock_seq_start(struct seq_file *seq, loff_t *pos)
        __acquires(rcu)
{
        rcu_read_lock();
        return *pos ? pn_sock_get_idx(seq, *pos - 1) : SEQ_START_TOKEN;
}

static void *pn_sock_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
        struct sock *sk;

        if (v == SEQ_START_TOKEN)
                sk = pn_sock_get_idx(seq, 0);
        else
                sk = pn_sock_get_next(seq, v);
        (*pos)++;
        return sk;
}

static void pn_sock_seq_stop(struct seq_file *seq, void *v)
        __releases(rcu)
{
        rcu_read_unlock();
}

static int pn_sock_seq_show(struct seq_file *seq, void *v)
{
        seq_setwidth(seq, 127);
        if (v == SEQ_START_TOKEN)
                seq_puts(seq, "pt  loc  rem rs st tx_queue rx_queue "
                        "  uid inode ref pointer drops");
        else {
                struct sock *sk = v;
                struct pn_sock *pn = pn_sk(sk);

                seq_printf(seq, "%2d %04X:%04X:%02X %02X %08X:%08X %5d %lu "
                        "%d %pK %u",
                        sk->sk_protocol, pn->sobject, pn->dobject,
                        pn->resource, sk->sk_state,
                        sk_wmem_alloc_get(sk), sk_rmem_alloc_get(sk),
                        from_kuid_munged(seq_user_ns(seq), sk_uid(sk)),
                        sock_i_ino(sk),
                        refcount_read(&sk->sk_refcnt), sk,
                        sk_drops_read(sk));
        }
        seq_pad(seq, '\n');
        return 0;
}

const struct seq_operations pn_sock_seq_ops = {
        .start = pn_sock_seq_start,
        .next = pn_sock_seq_next,
        .stop = pn_sock_seq_stop,
        .show = pn_sock_seq_show,
};
#endif

static struct  {
        struct sock __rcu *sk[256];
} pnres;

/*
 * Find and hold socket based on resource.
 */
struct sock *pn_find_sock_by_res(struct net *net, u8 res)
{
        struct sock *sk;

        if (!net_eq(net, &init_net))
                return NULL;

        rcu_read_lock();
        sk = rcu_dereference(pnres.sk[res]);
        if (sk)
                sock_hold(sk);
        rcu_read_unlock();
        return sk;
}

static DEFINE_MUTEX(resource_mutex);

int pn_sock_bind_res(struct sock *sk, u8 res)
{
        int ret = -EADDRINUSE;

        if (!net_eq(sock_net(sk), &init_net))
                return -ENOIOCTLCMD;
        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;
        if (pn_socket_autobind(sk->sk_socket))
                return -EAGAIN;

        mutex_lock(&resource_mutex);
        if (pnres.sk[res] == NULL) {
                sock_hold(sk);
                rcu_assign_pointer(pnres.sk[res], sk);
                ret = 0;
        }
        mutex_unlock(&resource_mutex);
        return ret;
}

int pn_sock_unbind_res(struct sock *sk, u8 res)
{
        int ret = -ENOENT;

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        mutex_lock(&resource_mutex);
        if (rcu_access_pointer(pnres.sk[res]) == sk) {
                RCU_INIT_POINTER(pnres.sk[res], NULL);
                ret = 0;
        }
        mutex_unlock(&resource_mutex);

        if (ret == 0) {
                synchronize_rcu();
                sock_put(sk);
        }
        return ret;
}

void pn_sock_unbind_all_res(struct sock *sk)
{
        unsigned int res, match = 0;

        mutex_lock(&resource_mutex);
        for (res = 0; res < 256; res++) {
                if (rcu_access_pointer(pnres.sk[res]) == sk) {
                        RCU_INIT_POINTER(pnres.sk[res], NULL);
                        match++;
                }
        }
        mutex_unlock(&resource_mutex);

        while (match > 0) {
                __sock_put(sk);
                match--;
        }
        /* Caller is responsible for RCU sync before final sock_put() */
}

#ifdef CONFIG_PROC_FS
static struct sock __rcu **pn_res_get_idx(struct seq_file *seq, loff_t pos)
{
        struct net *net = seq_file_net(seq);
        unsigned int i;

        if (!net_eq(net, &init_net))
                return NULL;

        for (i = 0; i < 256; i++) {
                if (rcu_access_pointer(pnres.sk[i]) == NULL)
                        continue;
                if (!pos)
                        return pnres.sk + i;
                pos--;
        }
        return NULL;
}

static struct sock __rcu **pn_res_get_next(struct seq_file *seq, struct sock __rcu **sk)
{
        struct net *net = seq_file_net(seq);
        unsigned int i;

        BUG_ON(!net_eq(net, &init_net));

        for (i = (sk - pnres.sk) + 1; i < 256; i++)
                if (pnres.sk[i])
                        return pnres.sk + i;
        return NULL;
}

static void *pn_res_seq_start(struct seq_file *seq, loff_t *pos)
        __acquires(resource_mutex)
{
        mutex_lock(&resource_mutex);
        return *pos ? pn_res_get_idx(seq, *pos - 1) : SEQ_START_TOKEN;
}

static void *pn_res_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
        struct sock __rcu **sk;

        if (v == SEQ_START_TOKEN)
                sk = pn_res_get_idx(seq, 0);
        else
                sk = pn_res_get_next(seq, v);
        (*pos)++;
        return sk;
}

static void pn_res_seq_stop(struct seq_file *seq, void *v)
        __releases(resource_mutex)
{
        mutex_unlock(&resource_mutex);
}

static int pn_res_seq_show(struct seq_file *seq, void *v)
{
        seq_setwidth(seq, 63);
        if (v == SEQ_START_TOKEN) {
                seq_puts(seq, "rs   uid inode");
        } else {
                struct sock __rcu **psk = v;
                struct sock *sk = rcu_dereference_protected(*psk,
                                        lockdep_is_held(&resource_mutex));

                seq_printf(seq, "%02X %5u %lu",
                           (int) (psk - pnres.sk),
                           from_kuid_munged(seq_user_ns(seq), sk_uid(sk)),
                           sock_i_ino(sk));
        }
        seq_pad(seq, '\n');
        return 0;
}

const struct seq_operations pn_res_seq_ops = {
        .start = pn_res_seq_start,
        .next = pn_res_seq_next,
        .stop = pn_res_seq_stop,
        .show = pn_res_seq_show,
};
#endif