socket.c

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/*
 * File: socket.c
 *
 * Phonet sockets
 *
 * Copyright (C) 2008 Nokia Corporation.
 *
 * Authors: Sakari Ailus <[email protected]>
 *          Rémi Denis-Courmont
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * version 2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA
 */

#include <linux/gfp.h>
#include <linux/kernel.h>
#include <linux/net.h>
#include <linux/poll.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 hlist_node *node;
    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, node, 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 hlist_node *node;
        struct sock *sknode;

        sk_for_each(sknode, node, 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();
}

void 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);
}
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 *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 */
    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 *)&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 *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,
                int flags)
{
    struct sock *sk = sock->sk;
    struct sock *newsk;
    int err;

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

    newsk = sk->sk_prot->accept(sk, flags, &err);
    if (!newsk)
        return 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 *sockaddr_len, 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);

    *sockaddr_len = sizeof(struct sockaddr_pn);
    return 0;
}

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

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

    if (sk->sk_state == TCP_CLOSE)
        return POLLERR;
    if (!skb_queue_empty(&sk->sk_receive_queue))
        mask |= POLLIN | POLLRDNORM;
    if (!skb_queue_empty(&pn->ctrlreq_queue))
        mask |= POLLPRI;
    if (!mask && sk->sk_state == TCP_CLOSE_WAIT)
        return POLLHUP;

    if (sk->sk_state == TCP_ESTABLISHED &&
        atomic_read(&sk->sk_wmem_alloc) < sk->sk_sndbuf &&
        atomic_read(&pn->tx_credits))
        mask |= POLLOUT | POLLWRNORM | POLLWRBAND;

    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);

        if (dev)
            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->sk_prot->ioctl(sk, cmd, 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 kiocb *iocb, 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(iocb, 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,
    .setsockopt = sock_no_setsockopt,
    .getsockopt = sock_no_getsockopt,
#ifdef CONFIG_COMPAT
    .compat_setsockopt = sock_no_setsockopt,
    .compat_getsockopt = sock_no_getsockopt,
#endif
    .sendmsg    = pn_socket_sendmsg,
    .recvmsg    = sock_common_recvmsg,
    .mmap       = sock_no_mmap,
    .sendpage   = sock_no_sendpage,
};

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,
#ifdef CONFIG_COMPAT
    .compat_setsockopt = compat_sock_common_setsockopt,
    .compat_getsockopt = compat_sock_common_getsockopt,
#endif
    .sendmsg    = pn_socket_sendmsg,
    .recvmsg    = sock_common_recvmsg,
    .mmap       = sock_no_mmap,
    .sendpage   = sock_no_sendpage,
};
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 hlist_node *node;
    struct sock *sknode;
    unsigned int h;

    for (h = 0; h < PN_HASHSIZE; h++) {
        sk_for_each_rcu(sknode, node, 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)
{
    int len;

    if (v == SEQ_START_TOKEN)
        seq_printf(seq, "%s%n", "pt  loc  rem rs st tx_queue rx_queue "
            "  uid inode ref pointer drops", &len);
    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 %d%n",
            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), sock_i_uid(sk)),
            sock_i_ino(sk),
            atomic_read(&sk->sk_refcnt), sk,
            atomic_read(&sk->sk_drops), &len);
    }
    seq_printf(seq, "%*s\n", 127 - len, "");
    return 0;
}

static 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,
};

static int pn_sock_open(struct inode *inode, struct file *file)
{
    return seq_open_net(inode, file, &pn_sock_seq_ops,
                sizeof(struct seq_net_private));
}

const struct file_operations pn_sock_seq_fops = {
    .owner = THIS_MODULE,
    .open = pn_sock_open,
    .read = seq_read,
    .llseek = seq_lseek,
    .release = seq_release_net,
};
#endif

static struct  {
    struct sock *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 (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 (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 **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 (pnres.sk[i] == NULL)
            continue;
        if (!pos)
            return pnres.sk + i;
        pos--;
    }
    return NULL;
}

static struct sock **pn_res_get_next(struct seq_file *seq, struct sock **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 **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)
{
    int len;

    if (v == SEQ_START_TOKEN)
        seq_printf(seq, "%s%n", "rs   uid inode", &len);
    else {
        struct sock **psk = v;
        struct sock *sk = *psk;

        seq_printf(seq, "%02X %5d %lu%n",
               (int) (psk - pnres.sk),
               from_kuid_munged(seq_user_ns(seq), sock_i_uid(sk)),
               sock_i_ino(sk), &len);
    }
    seq_printf(seq, "%*s\n", 63 - len, "");
    return 0;
}

static 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,
};

static int pn_res_open(struct inode *inode, struct file *file)
{
    return seq_open_net(inode, file, &pn_res_seq_ops,
                sizeof(struct seq_net_private));
}

const struct file_operations pn_res_seq_fops = {
    .owner = THIS_MODULE,
    .open = pn_res_open,
    .read = seq_read,
    .llseek = seq_lseek,
    .release = seq_release_net,
};
#endif