exec: do not sleep in TASK_TRACED under ->cred_guard_mutex

[linux-2.6/mini2440.git] / net / phonet / pep.c

/*
 * File: pep.c
 *
 * Phonet pipe protocol end point socket
 *
 * Copyright (C) 2008 Nokia Corporation.
 *
 * Author: Rémi Denis-Courmont <remi.denis-courmont@nokia.com>
 *
 * 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/kernel.h>
#include <linux/socket.h>
#include <net/sock.h>
#include <net/tcp_states.h>
#include <asm/ioctls.h>

#include <linux/phonet.h>
#include <net/phonet/phonet.h>
#include <net/phonet/pep.h>
#include <net/phonet/gprs.h>

/* sk_state values:
 * TCP_CLOSE            sock not in use yet
 * TCP_CLOSE_WAIT       disconnected pipe
 * TCP_LISTEN           listening pipe endpoint
 * TCP_SYN_RECV         connected pipe in disabled state
 * TCP_ESTABLISHED      connected pipe in enabled state
 *
 * pep_sock locking:
 *  - sk_state, ackq, hlist: sock lock needed
 *  - listener: read only
 *  - pipe_handle: read only
 */

#define CREDITS_MAX     10
#define CREDITS_THR     7

static const struct sockaddr_pn pipe_srv = {
        .spn_family = AF_PHONET,
        .spn_resource = 0xD9, /* pipe service */
};

#define pep_sb_size(s) (((s) + 5) & ~3) /* 2-bytes head, 32-bits aligned */

/* Get the next TLV sub-block. */
static unsigned char *pep_get_sb(struct sk_buff *skb, u8 *ptype, u8 *plen,
                                        void *buf)
{
        void *data = NULL;
        struct {
                u8 sb_type;
                u8 sb_len;
        } *ph, h;
        int buflen = *plen;

        ph = skb_header_pointer(skb, 0, 2, &h);
        if (ph == NULL || ph->sb_len < 2 || !pskb_may_pull(skb, ph->sb_len))
                return NULL;
        ph->sb_len -= 2;
        *ptype = ph->sb_type;
        *plen = ph->sb_len;

        if (buflen > ph->sb_len)
                buflen = ph->sb_len;
        data = skb_header_pointer(skb, 2, buflen, buf);
        __skb_pull(skb, 2 + ph->sb_len);
        return data;
}

static int pep_reply(struct sock *sk, struct sk_buff *oskb,
                        u8 code, const void *data, int len, gfp_t priority)
{
        const struct pnpipehdr *oph = pnp_hdr(oskb);
        struct pnpipehdr *ph;
        struct sk_buff *skb;

        skb = alloc_skb(MAX_PNPIPE_HEADER + len, priority);
        if (!skb)
                return -ENOMEM;
        skb_set_owner_w(skb, sk);

        skb_reserve(skb, MAX_PNPIPE_HEADER);
        __skb_put(skb, len);
        skb_copy_to_linear_data(skb, data, len);
        __skb_push(skb, sizeof(*ph));
        skb_reset_transport_header(skb);
        ph = pnp_hdr(skb);
        ph->utid = oph->utid;
        ph->message_id = oph->message_id + 1; /* REQ -> RESP */
        ph->pipe_handle = oph->pipe_handle;
        ph->error_code = code;

        return pn_skb_send(sk, skb, &pipe_srv);
}

#define PAD 0x00
static int pep_accept_conn(struct sock *sk, struct sk_buff *skb)
{
        static const u8 data[20] = {
                PAD, PAD, PAD, 2 /* sub-blocks */,
                PN_PIPE_SB_REQUIRED_FC_TX, pep_sb_size(5), 3, PAD,
                        PN_MULTI_CREDIT_FLOW_CONTROL,
                        PN_ONE_CREDIT_FLOW_CONTROL,
                        PN_LEGACY_FLOW_CONTROL,
                        PAD,
                PN_PIPE_SB_PREFERRED_FC_RX, pep_sb_size(5), 3, PAD,
                        PN_MULTI_CREDIT_FLOW_CONTROL,
                        PN_ONE_CREDIT_FLOW_CONTROL,
                        PN_LEGACY_FLOW_CONTROL,
                        PAD,
        };

        might_sleep();
        return pep_reply(sk, skb, PN_PIPE_NO_ERROR, data, sizeof(data),
                                GFP_KERNEL);
}

static int pep_reject_conn(struct sock *sk, struct sk_buff *skb, u8 code)
{
        static const u8 data[4] = { PAD, PAD, PAD, 0 /* sub-blocks */ };
        WARN_ON(code == PN_PIPE_NO_ERROR);
        return pep_reply(sk, skb, code, data, sizeof(data), GFP_ATOMIC);
}

/* Control requests are not sent by the pipe service and have a specific
 * message format. */
static int pep_ctrlreq_error(struct sock *sk, struct sk_buff *oskb, u8 code,
                                gfp_t priority)
{
        const struct pnpipehdr *oph = pnp_hdr(oskb);
        struct sk_buff *skb;
        struct pnpipehdr *ph;
        struct sockaddr_pn dst;

        skb = alloc_skb(MAX_PNPIPE_HEADER + 4, priority);
        if (!skb)
                return -ENOMEM;
        skb_set_owner_w(skb, sk);

        skb_reserve(skb, MAX_PHONET_HEADER);
        ph = (struct pnpipehdr *)skb_put(skb, sizeof(*ph) + 4);

        ph->utid = oph->utid;
        ph->message_id = PNS_PEP_CTRL_RESP;
        ph->pipe_handle = oph->pipe_handle;
        ph->data[0] = oph->data[1]; /* CTRL id */
        ph->data[1] = oph->data[0]; /* PEP type */
        ph->data[2] = code; /* error code, at an usual offset */
        ph->data[3] = PAD;
        ph->data[4] = PAD;

        pn_skb_get_src_sockaddr(oskb, &dst);
        return pn_skb_send(sk, skb, &dst);
}

static int pipe_snd_status(struct sock *sk, u8 type, u8 status, gfp_t priority)
{
        struct pep_sock *pn = pep_sk(sk);
        struct pnpipehdr *ph;
        struct sk_buff *skb;

        skb = alloc_skb(MAX_PNPIPE_HEADER + 4, priority);
        if (!skb)
                return -ENOMEM;
        skb_set_owner_w(skb, sk);

        skb_reserve(skb, MAX_PNPIPE_HEADER + 4);
        __skb_push(skb, sizeof(*ph) + 4);
        skb_reset_transport_header(skb);
        ph = pnp_hdr(skb);
        ph->utid = 0;
        ph->message_id = PNS_PEP_STATUS_IND;
        ph->pipe_handle = pn->pipe_handle;
        ph->pep_type = PN_PEP_TYPE_COMMON;
        ph->data[1] = type;
        ph->data[2] = PAD;
        ph->data[3] = PAD;
        ph->data[4] = status;

        return pn_skb_send(sk, skb, &pipe_srv);
}

/* Send our RX flow control information to the sender.
 * Socket must be locked. */
static void pipe_grant_credits(struct sock *sk)
{
        struct pep_sock *pn = pep_sk(sk);

        BUG_ON(sk->sk_state != TCP_ESTABLISHED);

        switch (pn->rx_fc) {
        case PN_LEGACY_FLOW_CONTROL: /* TODO */
                break;
        case PN_ONE_CREDIT_FLOW_CONTROL:
                pipe_snd_status(sk, PN_PEP_IND_FLOW_CONTROL,
                                PEP_IND_READY, GFP_ATOMIC);
                pn->rx_credits = 1;
                break;
        case PN_MULTI_CREDIT_FLOW_CONTROL:
                if ((pn->rx_credits + CREDITS_THR) > CREDITS_MAX)
                        break;
                if (pipe_snd_status(sk, PN_PEP_IND_ID_MCFC_GRANT_CREDITS,
                                        CREDITS_MAX - pn->rx_credits,
                                        GFP_ATOMIC) == 0)
                        pn->rx_credits = CREDITS_MAX;
                break;
        }
}

static int pipe_rcv_status(struct sock *sk, struct sk_buff *skb)
{
        struct pep_sock *pn = pep_sk(sk);
        struct pnpipehdr *hdr = pnp_hdr(skb);
        int wake = 0;

        if (!pskb_may_pull(skb, sizeof(*hdr) + 4))
                return -EINVAL;

        if (hdr->data[0] != PN_PEP_TYPE_COMMON) {
                LIMIT_NETDEBUG(KERN_DEBUG"Phonet unknown PEP type: %u\n",
                                (unsigned)hdr->data[0]);
                return -EOPNOTSUPP;
        }

        switch (hdr->data[1]) {
        case PN_PEP_IND_FLOW_CONTROL:
                switch (pn->tx_fc) {
                case PN_LEGACY_FLOW_CONTROL:
                        switch (hdr->data[4]) {
                        case PEP_IND_BUSY:
                                atomic_set(&pn->tx_credits, 0);
                                break;
                        case PEP_IND_READY:
                                atomic_set(&pn->tx_credits, wake = 1);
                                break;
                        }
                        break;
                case PN_ONE_CREDIT_FLOW_CONTROL:
                        if (hdr->data[4] == PEP_IND_READY)
                                atomic_set(&pn->tx_credits, wake = 1);
                        break;
                }
                break;

        case PN_PEP_IND_ID_MCFC_GRANT_CREDITS:
                if (pn->tx_fc != PN_MULTI_CREDIT_FLOW_CONTROL)
                        break;
                atomic_add(wake = hdr->data[4], &pn->tx_credits);
                break;

        default:
                LIMIT_NETDEBUG(KERN_DEBUG"Phonet unknown PEP indication: %u\n",
                                (unsigned)hdr->data[1]);
                return -EOPNOTSUPP;
        }
        if (wake)
                sk->sk_write_space(sk);
        return 0;
}

static int pipe_rcv_created(struct sock *sk, struct sk_buff *skb)
{
        struct pep_sock *pn = pep_sk(sk);
        struct pnpipehdr *hdr = pnp_hdr(skb);
        u8 n_sb = hdr->data[0];

        pn->rx_fc = pn->tx_fc = PN_LEGACY_FLOW_CONTROL;
        __skb_pull(skb, sizeof(*hdr));
        while (n_sb > 0) {
                u8 type, buf[2], len = sizeof(buf);
                u8 *data = pep_get_sb(skb, &type, &len, buf);

                if (data == NULL)
                        return -EINVAL;
                switch (type) {
                case PN_PIPE_SB_NEGOTIATED_FC:
                        if (len < 2 || (data[0] | data[1]) > 3)
                                break;
                        pn->tx_fc = data[0] & 3;
                        pn->rx_fc = data[1] & 3;
                        break;
                }
                n_sb--;
        }
        return 0;
}

/* Queue an skb to a connected sock.
 * Socket lock must be held. */
static int pipe_do_rcv(struct sock *sk, struct sk_buff *skb)
{
        struct pep_sock *pn = pep_sk(sk);
        struct pnpipehdr *hdr = pnp_hdr(skb);
        struct sk_buff_head *queue;
        int err = 0;

        BUG_ON(sk->sk_state == TCP_CLOSE_WAIT);

        switch (hdr->message_id) {
        case PNS_PEP_CONNECT_REQ:
                pep_reject_conn(sk, skb, PN_PIPE_ERR_PEP_IN_USE);
                break;

        case PNS_PEP_DISCONNECT_REQ:
                pep_reply(sk, skb, PN_PIPE_NO_ERROR, NULL, 0, GFP_ATOMIC);
                sk->sk_state = TCP_CLOSE_WAIT;
                if (!sock_flag(sk, SOCK_DEAD))
                        sk->sk_state_change(sk);
                break;

        case PNS_PEP_ENABLE_REQ:
                /* Wait for PNS_PIPE_(ENABLED|REDIRECTED)_IND */
                pep_reply(sk, skb, PN_PIPE_NO_ERROR, NULL, 0, GFP_ATOMIC);
                break;

        case PNS_PEP_RESET_REQ:
                switch (hdr->state_after_reset) {
                case PN_PIPE_DISABLE:
                        pn->init_enable = 0;
                        break;
                case PN_PIPE_ENABLE:
                        pn->init_enable = 1;
                        break;
                default: /* not allowed to send an error here!? */
                        err = -EINVAL;
                        goto out;
                }
                /* fall through */
        case PNS_PEP_DISABLE_REQ:
                atomic_set(&pn->tx_credits, 0);
                pep_reply(sk, skb, PN_PIPE_NO_ERROR, NULL, 0, GFP_ATOMIC);
                break;

        case PNS_PEP_CTRL_REQ:
                if (skb_queue_len(&pn->ctrlreq_queue) >= PNPIPE_CTRLREQ_MAX)
                        break;
                __skb_pull(skb, 4);
                queue = &pn->ctrlreq_queue;
                goto queue;

        case PNS_PIPE_DATA:
                __skb_pull(skb, 3); /* Pipe data header */
                if (!pn_flow_safe(pn->rx_fc)) {
                        err = sock_queue_rcv_skb(sk, skb);
                        if (!err)
                                return 0;
                        break;
                }

                if (pn->rx_credits == 0) {
                        err = -ENOBUFS;
                        break;
                }
                pn->rx_credits--;
                queue = &sk->sk_receive_queue;
                goto queue;

        case PNS_PEP_STATUS_IND:
                pipe_rcv_status(sk, skb);
                break;

        case PNS_PIPE_REDIRECTED_IND:
                err = pipe_rcv_created(sk, skb);
                break;

        case PNS_PIPE_CREATED_IND:
                err = pipe_rcv_created(sk, skb);
                if (err)
                        break;
                /* fall through */
        case PNS_PIPE_RESET_IND:
                if (!pn->init_enable)
                        break;
                /* fall through */
        case PNS_PIPE_ENABLED_IND:
                if (!pn_flow_safe(pn->tx_fc)) {
                        atomic_set(&pn->tx_credits, 1);
                        sk->sk_write_space(sk);
                }
                if (sk->sk_state == TCP_ESTABLISHED)
                        break; /* Nothing to do */
                sk->sk_state = TCP_ESTABLISHED;
                pipe_grant_credits(sk);
                break;

        case PNS_PIPE_DISABLED_IND:
                sk->sk_state = TCP_SYN_RECV;
                pn->rx_credits = 0;
                break;

        default:
                LIMIT_NETDEBUG(KERN_DEBUG"Phonet unknown PEP message: %u\n",
                                hdr->message_id);
                err = -EINVAL;
        }
out:
        kfree_skb(skb);
        return err;

queue:
        skb->dev = NULL;
        skb_set_owner_r(skb, sk);
        err = skb->len;
        skb_queue_tail(queue, skb);
        if (!sock_flag(sk, SOCK_DEAD))
                sk->sk_data_ready(sk, err);
        return 0;
}

/* Destroy connected sock. */
static void pipe_destruct(struct sock *sk)
{
        struct pep_sock *pn = pep_sk(sk);

        skb_queue_purge(&sk->sk_receive_queue);
        skb_queue_purge(&pn->ctrlreq_queue);
}

static int pep_connreq_rcv(struct sock *sk, struct sk_buff *skb)
{
        struct sock *newsk;
        struct pep_sock *newpn, *pn = pep_sk(sk);
        struct pnpipehdr *hdr;
        struct sockaddr_pn dst;
        u16 peer_type;
        u8 pipe_handle, enabled, n_sb;

        if (!pskb_pull(skb, sizeof(*hdr) + 4))
                return -EINVAL;

        hdr = pnp_hdr(skb);
        pipe_handle = hdr->pipe_handle;
        switch (hdr->state_after_connect) {
        case PN_PIPE_DISABLE:
                enabled = 0;
                break;
        case PN_PIPE_ENABLE:
                enabled = 1;
                break;
        default:
                pep_reject_conn(sk, skb, PN_PIPE_ERR_INVALID_PARAM);
                return -EINVAL;
        }
        peer_type = hdr->other_pep_type << 8;

        if (unlikely(sk->sk_state != TCP_LISTEN) || sk_acceptq_is_full(sk)) {
                pep_reject_conn(sk, skb, PN_PIPE_ERR_PEP_IN_USE);
                return -ENOBUFS;
        }

        /* Parse sub-blocks (options) */
        n_sb = hdr->data[4];
        while (n_sb > 0) {
                u8 type, buf[1], len = sizeof(buf);
                const u8 *data = pep_get_sb(skb, &type, &len, buf);

                if (data == NULL)
                        return -EINVAL;
                switch (type) {
                case PN_PIPE_SB_CONNECT_REQ_PEP_SUB_TYPE:
                        if (len < 1)
                                return -EINVAL;
                        peer_type = (peer_type & 0xff00) | data[0];
                        break;
                }
                n_sb--;
        }

        skb = skb_clone(skb, GFP_ATOMIC);
        if (!skb)
                return -ENOMEM;

        /* Create a new to-be-accepted sock */
        newsk = sk_alloc(sock_net(sk), PF_PHONET, GFP_ATOMIC, sk->sk_prot);
        if (!newsk) {
                kfree_skb(skb);
                return -ENOMEM;
        }
        sock_init_data(NULL, newsk);
        newsk->sk_state = TCP_SYN_RECV;
        newsk->sk_backlog_rcv = pipe_do_rcv;
        newsk->sk_protocol = sk->sk_protocol;
        newsk->sk_destruct = pipe_destruct;

        newpn = pep_sk(newsk);
        pn_skb_get_dst_sockaddr(skb, &dst);
        newpn->pn_sk.sobject = pn_sockaddr_get_object(&dst);
        newpn->pn_sk.resource = pn->pn_sk.resource;
        skb_queue_head_init(&newpn->ctrlreq_queue);
        newpn->pipe_handle = pipe_handle;
        atomic_set(&newpn->tx_credits, 0);
        newpn->peer_type = peer_type;
        newpn->rx_credits = 0;
        newpn->rx_fc = newpn->tx_fc = PN_LEGACY_FLOW_CONTROL;
        newpn->init_enable = enabled;

        BUG_ON(!skb_queue_empty(&newsk->sk_receive_queue));
        skb_queue_head(&newsk->sk_receive_queue, skb);
        if (!sock_flag(sk, SOCK_DEAD))
                sk->sk_data_ready(sk, 0);

        sk_acceptq_added(sk);
        sk_add_node(newsk, &pn->ackq);
        return 0;
}

/* Listening sock must be locked */
static struct sock *pep_find_pipe(const struct hlist_head *hlist,
                                        const struct sockaddr_pn *dst,
                                        u8 pipe_handle)
{
        struct hlist_node *node;
        struct sock *sknode;
        u16 dobj = pn_sockaddr_get_object(dst);

        sk_for_each(sknode, node, hlist) {
                struct pep_sock *pnnode = pep_sk(sknode);

                /* Ports match, but addresses might not: */
                if (pnnode->pn_sk.sobject != dobj)
                        continue;
                if (pnnode->pipe_handle != pipe_handle)
                        continue;
                if (sknode->sk_state == TCP_CLOSE_WAIT)
                        continue;

                sock_hold(sknode);
                return sknode;
        }
        return NULL;
}

/*
 * Deliver an skb to a listening sock.
 * Socket lock must be held.
 * We then queue the skb to the right connected sock (if any).
 */
static int pep_do_rcv(struct sock *sk, struct sk_buff *skb)
{
        struct pep_sock *pn = pep_sk(sk);
        struct sock *sknode;
        struct pnpipehdr *hdr;
        struct sockaddr_pn dst;
        int err = NET_RX_SUCCESS;
        u8 pipe_handle;

        if (!pskb_may_pull(skb, sizeof(*hdr)))
                goto drop;

        hdr = pnp_hdr(skb);
        pipe_handle = hdr->pipe_handle;
        if (pipe_handle == PN_PIPE_INVALID_HANDLE)
                goto drop;

        pn_skb_get_dst_sockaddr(skb, &dst);

        /* Look for an existing pipe handle */
        sknode = pep_find_pipe(&pn->hlist, &dst, pipe_handle);
        if (sknode)
                return sk_receive_skb(sknode, skb, 1);

        /* Look for a pipe handle pending accept */
        sknode = pep_find_pipe(&pn->ackq, &dst, pipe_handle);
        if (sknode) {
                sock_put(sknode);
                if (net_ratelimit())
                        printk(KERN_WARNING"Phonet unconnected PEP ignored");
                err = NET_RX_DROP;
                goto drop;
        }

        switch (hdr->message_id) {
        case PNS_PEP_CONNECT_REQ:
                err = pep_connreq_rcv(sk, skb);
                break;

        case PNS_PEP_DISCONNECT_REQ:
                pep_reply(sk, skb, PN_PIPE_NO_ERROR, NULL, 0, GFP_ATOMIC);
                break;

        case PNS_PEP_CTRL_REQ:
                pep_ctrlreq_error(sk, skb, PN_PIPE_INVALID_HANDLE, GFP_ATOMIC);
                break;

        case PNS_PEP_RESET_REQ:
        case PNS_PEP_ENABLE_REQ:
        case PNS_PEP_DISABLE_REQ:
                /* invalid handle is not even allowed here! */
        default:
                err = NET_RX_DROP;
        }
drop:
        kfree_skb(skb);
        return err;
}

/* associated socket ceases to exist */
static void pep_sock_close(struct sock *sk, long timeout)
{
        struct pep_sock *pn = pep_sk(sk);
        int ifindex = 0;

        sk_common_release(sk);

        lock_sock(sk);
        if (sk->sk_state == TCP_LISTEN) {
                /* Destroy the listen queue */
                struct sock *sknode;
                struct hlist_node *p, *n;

                sk_for_each_safe(sknode, p, n, &pn->ackq)
                        sk_del_node_init(sknode);
                sk->sk_state = TCP_CLOSE;
        }
        ifindex = pn->ifindex;
        pn->ifindex = 0;
        release_sock(sk);

        if (ifindex)
                gprs_detach(sk);
}

static int pep_wait_connreq(struct sock *sk, int noblock)
{
        struct task_struct *tsk = current;
        struct pep_sock *pn = pep_sk(sk);
        long timeo = sock_rcvtimeo(sk, noblock);

        for (;;) {
                DEFINE_WAIT(wait);

                if (sk->sk_state != TCP_LISTEN)
                        return -EINVAL;
                if (!hlist_empty(&pn->ackq))
                        break;
                if (!timeo)
                        return -EWOULDBLOCK;
                if (signal_pending(tsk))
                        return sock_intr_errno(timeo);

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

        return 0;
}

static struct sock *pep_sock_accept(struct sock *sk, int flags, int *errp)
{
        struct pep_sock *pn = pep_sk(sk);
        struct sock *newsk = NULL;
        struct sk_buff *oskb;
        int err;

        lock_sock(sk);
        err = pep_wait_connreq(sk, flags & O_NONBLOCK);
        if (err)
                goto out;

        newsk = __sk_head(&pn->ackq);

        oskb = skb_dequeue(&newsk->sk_receive_queue);
        err = pep_accept_conn(newsk, oskb);
        if (err) {
                skb_queue_head(&newsk->sk_receive_queue, oskb);
                newsk = NULL;
                goto out;
        }

        sock_hold(sk);
        pep_sk(newsk)->listener = sk;

        sock_hold(newsk);
        sk_del_node_init(newsk);
        sk_acceptq_removed(sk);
        sk_add_node(newsk, &pn->hlist);
        __sock_put(newsk);

out:
        release_sock(sk);
        *errp = err;
        return newsk;
}

static int pep_ioctl(struct sock *sk, int cmd, unsigned long arg)
{
        struct pep_sock *pn = pep_sk(sk);
        int answ;

        switch (cmd) {
        case SIOCINQ:
                if (sk->sk_state == TCP_LISTEN)
                        return -EINVAL;

                lock_sock(sk);
                if (sock_flag(sk, SOCK_URGINLINE)
                 && !skb_queue_empty(&pn->ctrlreq_queue))
                        answ = skb_peek(&pn->ctrlreq_queue)->len;
                else if (!skb_queue_empty(&sk->sk_receive_queue))
                        answ = skb_peek(&sk->sk_receive_queue)->len;
                else
                        answ = 0;
                release_sock(sk);
                return put_user(answ, (int __user *)arg);
        }

        return -ENOIOCTLCMD;
}

static int pep_init(struct sock *sk)
{
        struct pep_sock *pn = pep_sk(sk);

        INIT_HLIST_HEAD(&pn->ackq);
        INIT_HLIST_HEAD(&pn->hlist);
        skb_queue_head_init(&pn->ctrlreq_queue);
        pn->pipe_handle = PN_PIPE_INVALID_HANDLE;
        return 0;
}

static int pep_setsockopt(struct sock *sk, int level, int optname,
                                char __user *optval, int optlen)
{
        struct pep_sock *pn = pep_sk(sk);
        int val = 0, err = 0;

        if (level != SOL_PNPIPE)
                return -ENOPROTOOPT;
        if (optlen >= sizeof(int)) {
                if (get_user(val, (int __user *) optval))
                        return -EFAULT;
        }

        lock_sock(sk);
        switch (optname) {
        case PNPIPE_ENCAP:
                if (val && val != PNPIPE_ENCAP_IP) {
                        err = -EINVAL;
                        break;
                }
                if (!pn->ifindex == !val)
                        break; /* Nothing to do! */
                if (!capable(CAP_NET_ADMIN)) {
                        err = -EPERM;
                        break;
                }
                if (val) {
                        release_sock(sk);
                        err = gprs_attach(sk);
                        if (err > 0) {
                                pn->ifindex = err;
                                err = 0;
                        }
                } else {
                        pn->ifindex = 0;
                        release_sock(sk);
                        gprs_detach(sk);
                        err = 0;
                }
                goto out_norel;
        default:
                err = -ENOPROTOOPT;
        }
        release_sock(sk);

out_norel:
        return err;
}

static int pep_getsockopt(struct sock *sk, int level, int optname,
                                char __user *optval, int __user *optlen)
{
        struct pep_sock *pn = pep_sk(sk);
        int len, val;

        if (level != SOL_PNPIPE)
                return -ENOPROTOOPT;
        if (get_user(len, optlen))
                return -EFAULT;

        switch (optname) {
        case PNPIPE_ENCAP:
                val = pn->ifindex ? PNPIPE_ENCAP_IP : PNPIPE_ENCAP_NONE;
                break;
        case PNPIPE_IFINDEX:
                val = pn->ifindex;
                break;
        default:
                return -ENOPROTOOPT;
        }

        len = min_t(unsigned int, sizeof(int), len);
        if (put_user(len, optlen))
                return -EFAULT;
        if (put_user(val, (int __user *) optval))
                return -EFAULT;
        return 0;
}

static int pipe_skb_send(struct sock *sk, struct sk_buff *skb)
{
        struct pep_sock *pn = pep_sk(sk);
        struct pnpipehdr *ph;

        if (pn_flow_safe(pn->tx_fc) &&
            !atomic_add_unless(&pn->tx_credits, -1, 0)) {
                kfree_skb(skb);
                return -ENOBUFS;
        }

        skb_push(skb, 3);
        skb_reset_transport_header(skb);
        ph = pnp_hdr(skb);
        ph->utid = 0;
        ph->message_id = PNS_PIPE_DATA;
        ph->pipe_handle = pn->pipe_handle;

        return pn_skb_send(sk, skb, &pipe_srv);
}

static int pep_sendmsg(struct kiocb *iocb, struct sock *sk,
                        struct msghdr *msg, size_t len)
{
        struct pep_sock *pn = pep_sk(sk);
        struct sk_buff *skb = NULL;
        long timeo;
        int flags = msg->msg_flags;
        int err, done;

        if (msg->msg_flags & MSG_OOB || !(msg->msg_flags & MSG_EOR))
                return -EOPNOTSUPP;

        lock_sock(sk);
        timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
        if ((1 << sk->sk_state) & (TCPF_LISTEN|TCPF_CLOSE)) {
                err = -ENOTCONN;
                goto out;
        }
        if (sk->sk_state != TCP_ESTABLISHED) {
                /* Wait until the pipe gets to enabled state */
disabled:
                err = sk_stream_wait_connect(sk, &timeo);
                if (err)
                        goto out;

                if (sk->sk_state == TCP_CLOSE_WAIT) {
                        err = -ECONNRESET;
                        goto out;
                }
        }
        BUG_ON(sk->sk_state != TCP_ESTABLISHED);

        /* Wait until flow control allows TX */
        done = atomic_read(&pn->tx_credits);
        while (!done) {
                DEFINE_WAIT(wait);

                if (!timeo) {
                        err = -EAGAIN;
                        goto out;
                }
                if (signal_pending(current)) {
                        err = sock_intr_errno(timeo);
                        goto out;
                }

                prepare_to_wait(&sk->sk_socket->wait, &wait,
                                TASK_INTERRUPTIBLE);
                done = sk_wait_event(sk, &timeo, atomic_read(&pn->tx_credits));
                finish_wait(&sk->sk_socket->wait, &wait);

                if (sk->sk_state != TCP_ESTABLISHED)
                        goto disabled;
        }

        if (!skb) {
                skb = sock_alloc_send_skb(sk, MAX_PNPIPE_HEADER + len,
                                                flags & MSG_DONTWAIT, &err);
                if (skb == NULL)
                        goto out;
                skb_reserve(skb, MAX_PHONET_HEADER + 3);

                if (sk->sk_state != TCP_ESTABLISHED ||
                    !atomic_read(&pn->tx_credits))
                        goto disabled; /* sock_alloc_send_skb might sleep */
        }

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

        err = pipe_skb_send(sk, skb);
        if (err >= 0)
                err = len; /* success! */
        skb = NULL;
out:
        release_sock(sk);
        kfree_skb(skb);
        return err;
}

int pep_writeable(struct sock *sk)
{
        struct pep_sock *pn = pep_sk(sk);

        return atomic_read(&pn->tx_credits);
}

int pep_write(struct sock *sk, struct sk_buff *skb)
{
        struct sk_buff *rskb, *fs;
        int flen = 0;

        rskb = alloc_skb(MAX_PNPIPE_HEADER, GFP_ATOMIC);
        if (!rskb) {
                kfree_skb(skb);
                return -ENOMEM;
        }
        skb_shinfo(rskb)->frag_list = skb;
        rskb->len += skb->len;
        rskb->data_len += rskb->len;
        rskb->truesize += rskb->len;

        /* Avoid nested fragments */
        skb_walk_frags(skb, fs)
                flen += fs->len;
        skb->next = skb_shinfo(skb)->frag_list;
        skb_frag_list_init(skb);
        skb->len -= flen;
        skb->data_len -= flen;
        skb->truesize -= flen;

        skb_reserve(rskb, MAX_PHONET_HEADER + 3);
        return pipe_skb_send(sk, rskb);
}

struct sk_buff *pep_read(struct sock *sk)
{
        struct sk_buff *skb = skb_dequeue(&sk->sk_receive_queue);

        if (sk->sk_state == TCP_ESTABLISHED)
                pipe_grant_credits(sk);
        return skb;
}

static int pep_recvmsg(struct kiocb *iocb, struct sock *sk,
                        struct msghdr *msg, size_t len, int noblock,
                        int flags, int *addr_len)
{
        struct sk_buff *skb;
        int err;

        if (unlikely(1 << sk->sk_state & (TCPF_LISTEN | TCPF_CLOSE)))
                return -ENOTCONN;

        if ((flags & MSG_OOB) || sock_flag(sk, SOCK_URGINLINE)) {
                /* Dequeue and acknowledge control request */
                struct pep_sock *pn = pep_sk(sk);

                skb = skb_dequeue(&pn->ctrlreq_queue);
                if (skb) {
                        pep_ctrlreq_error(sk, skb, PN_PIPE_NO_ERROR,
                                                GFP_KERNEL);
                        msg->msg_flags |= MSG_OOB;
                        goto copy;
                }
                if (flags & MSG_OOB)
                        return -EINVAL;
        }

        skb = skb_recv_datagram(sk, flags, noblock, &err);
        lock_sock(sk);
        if (skb == NULL) {
                if (err == -ENOTCONN && sk->sk_state == TCP_CLOSE_WAIT)
                        err = -ECONNRESET;
                release_sock(sk);
                return err;
        }

        if (sk->sk_state == TCP_ESTABLISHED)
                pipe_grant_credits(sk);
        release_sock(sk);
copy:
        msg->msg_flags |= MSG_EOR;
        if (skb->len > len)
                msg->msg_flags |= MSG_TRUNC;
        else
                len = skb->len;

        err = skb_copy_datagram_iovec(skb, 0, msg->msg_iov, len);
        if (!err)
                err = (flags & MSG_TRUNC) ? skb->len : len;

        skb_free_datagram(sk, skb);
        return err;
}

static void pep_sock_unhash(struct sock *sk)
{
        struct pep_sock *pn = pep_sk(sk);
        struct sock *skparent = NULL;

        lock_sock(sk);
        if ((1 << sk->sk_state) & ~(TCPF_CLOSE|TCPF_LISTEN)) {
                skparent = pn->listener;
                sk_del_node_init(sk);
                release_sock(sk);

                sk = skparent;
                pn = pep_sk(skparent);
                lock_sock(sk);
        }
        /* Unhash a listening sock only when it is closed
         * and all of its active connected pipes are closed. */
        if (hlist_empty(&pn->hlist))
                pn_sock_unhash(&pn->pn_sk.sk);
        release_sock(sk);

        if (skparent)
                sock_put(skparent);
}

static struct proto pep_proto = {
        .close          = pep_sock_close,
        .accept         = pep_sock_accept,
        .ioctl          = pep_ioctl,
        .init           = pep_init,
        .setsockopt     = pep_setsockopt,
        .getsockopt     = pep_getsockopt,
        .sendmsg        = pep_sendmsg,
        .recvmsg        = pep_recvmsg,
        .backlog_rcv    = pep_do_rcv,
        .hash           = pn_sock_hash,
        .unhash         = pep_sock_unhash,
        .get_port       = pn_sock_get_port,
        .obj_size       = sizeof(struct pep_sock),
        .owner          = THIS_MODULE,
        .name           = "PNPIPE",
};

static struct phonet_protocol pep_pn_proto = {
        .ops            = &phonet_stream_ops,
        .prot           = &pep_proto,
        .sock_type      = SOCK_SEQPACKET,
};

static int __init pep_register(void)
{
        return phonet_proto_register(PN_PROTO_PIPE, &pep_pn_proto);
}

static void __exit pep_unregister(void)
{
        phonet_proto_unregister(PN_PROTO_PIPE, &pep_pn_proto);
}

module_init(pep_register);
module_exit(pep_unregister);
MODULE_AUTHOR("Remi Denis-Courmont, Nokia");
MODULE_DESCRIPTION("Phonet pipe protocol");
MODULE_LICENSE("GPL");
MODULE_ALIAS_NET_PF_PROTO(PF_PHONET, PN_PROTO_PIPE);