svc.c

// SPDX-License-Identifier: GPL-2.0
/* net/atm/svc.c - ATM SVC sockets */

/* Written 1995-2000 by Werner Almesberger, EPFL LRC/ICA */

#define pr_fmt(fmt) KBUILD_MODNAME ":%s: " fmt, __func__

#include <linux/string.h>
#include <linux/net.h>		/* struct socket, struct proto_ops */
#include <linux/errno.h>	/* error codes */
#include <linux/kernel.h>	/* printk */
#include <linux/skbuff.h>
#include <linux/wait.h>
#include <linux/sched/signal.h>
#include <linux/fcntl.h>	/* O_NONBLOCK */
#include <linux/init.h>
#include <linux/atm.h>		/* ATM stuff */
#include <linux/atmsap.h>
#include <linux/atmsvc.h>
#include <linux/atmdev.h>
#include <linux/bitops.h>
#include <net/sock.h>		/* for sock_no_* */
#include <linux/uaccess.h>
#include <linux/export.h>

#include "resources.h"
#include "common.h"		/* common for PVCs and SVCs */
#include "signaling.h"
#include "addr.h"

static int svc_create(struct net *net, struct socket *sock, int protocol,
		      int kern);

/*
 * Note: since all this is still nicely synchronized with the signaling demon,
 *       there's no need to protect sleep loops with clis. If signaling is
 *       moved into the kernel, that would change.
 */


static int svc_shutdown(struct socket *sock, int how)
{
	return 0;
}

static void svc_disconnect(struct atm_vcc *vcc)
{
	DEFINE_WAIT(wait);
	struct sk_buff *skb;
	struct sock *sk = sk_atm(vcc);

	pr_debug("%p\n", vcc);
	if (test_bit(ATM_VF_REGIS, &vcc->flags)) {
		sigd_enq(vcc, as_close, NULL, NULL, NULL);
		for (;;) {
			prepare_to_wait(sk_sleep(sk), &wait, TASK_UNINTERRUPTIBLE);
			if (test_bit(ATM_VF_RELEASED, &vcc->flags) || !sigd)
				break;
			schedule();
		}
		finish_wait(sk_sleep(sk), &wait);
	}
	/* beware - socket is still in use by atmsigd until the last
	   as_indicate has been answered */
	while ((skb = skb_dequeue(&sk->sk_receive_queue)) != NULL) {
		atm_return(vcc, skb->truesize);
		pr_debug("LISTEN REL\n");
		sigd_enq2(NULL, as_reject, vcc, NULL, NULL, &vcc->qos, 0);
		dev_kfree_skb(skb);
	}
	clear_bit(ATM_VF_REGIS, &vcc->flags);
	/* ... may retry later */
}

static int svc_release(struct socket *sock)
{
	struct sock *sk = sock->sk;
	struct atm_vcc *vcc;

	if (sk) {
		vcc = ATM_SD(sock);
		pr_debug("%p\n", vcc);
		clear_bit(ATM_VF_READY, &vcc->flags);
		/*
		 * VCC pointer is used as a reference,
		 * so we must not free it (thereby subjecting it to re-use)
		 * before all pending connections are closed
		 */
		svc_disconnect(vcc);
		vcc_release(sock);
	}
	return 0;
}

static int svc_bind(struct socket *sock, struct sockaddr *sockaddr,
		    int sockaddr_len)
{
	DEFINE_WAIT(wait);
	struct sock *sk = sock->sk;
	struct sockaddr_atmsvc *addr;
	struct atm_vcc *vcc;
	int error;

	if (sockaddr_len != sizeof(struct sockaddr_atmsvc))
		return -EINVAL;
	lock_sock(sk);
	if (sock->state == SS_CONNECTED) {
		error = -EISCONN;
		goto out;
	}
	if (sock->state != SS_UNCONNECTED) {
		error = -EINVAL;
		goto out;
	}
	vcc = ATM_SD(sock);
	addr = (struct sockaddr_atmsvc *) sockaddr;
	if (addr->sas_family != AF_ATMSVC) {
		error = -EAFNOSUPPORT;
		goto out;
	}
	clear_bit(ATM_VF_BOUND, &vcc->flags);
	    /* failing rebind will kill old binding */
	/* @@@ check memory (de)allocation on rebind */
	if (!test_bit(ATM_VF_HASQOS, &vcc->flags)) {
		error = -EBADFD;
		goto out;
	}
	vcc->local = *addr;
	set_bit(ATM_VF_WAITING, &vcc->flags);
	sigd_enq(vcc, as_bind, NULL, NULL, &vcc->local);
	for (;;) {
		prepare_to_wait(sk_sleep(sk), &wait, TASK_UNINTERRUPTIBLE);
		if (!test_bit(ATM_VF_WAITING, &vcc->flags) || !sigd)
			break;
		schedule();
	}
	finish_wait(sk_sleep(sk), &wait);
	clear_bit(ATM_VF_REGIS, &vcc->flags); /* doesn't count */
	if (!sigd) {
		error = -EUNATCH;
		goto out;
	}
	if (!sk->sk_err)
		set_bit(ATM_VF_BOUND, &vcc->flags);
	error = -sk->sk_err;
out:
	release_sock(sk);
	return error;
}

static int svc_connect(struct socket *sock, struct sockaddr *sockaddr,
		       int sockaddr_len, int flags)
{
	DEFINE_WAIT(wait);
	struct sock *sk = sock->sk;
	struct sockaddr_atmsvc *addr;
	struct atm_vcc *vcc = ATM_SD(sock);
	int error;

	pr_debug("%p\n", vcc);
	lock_sock(sk);
	if (sockaddr_len != sizeof(struct sockaddr_atmsvc)) {
		error = -EINVAL;
		goto out;
	}

	switch (sock->state) {
	default:
		error = -EINVAL;
		goto out;
	case SS_CONNECTED:
		error = -EISCONN;
		goto out;
	case SS_CONNECTING:
		if (test_bit(ATM_VF_WAITING, &vcc->flags)) {
			error = -EALREADY;
			goto out;
		}
		sock->state = SS_UNCONNECTED;
		if (sk->sk_err) {
			error = -sk->sk_err;
			goto out;
		}
		break;
	case SS_UNCONNECTED:
		addr = (struct sockaddr_atmsvc *) sockaddr;
		if (addr->sas_family != AF_ATMSVC) {
			error = -EAFNOSUPPORT;
			goto out;
		}
		if (!test_bit(ATM_VF_HASQOS, &vcc->flags)) {
			error = -EBADFD;
			goto out;
		}
		if (vcc->qos.txtp.traffic_class == ATM_ANYCLASS ||
		    vcc->qos.rxtp.traffic_class == ATM_ANYCLASS) {
			error = -EINVAL;
			goto out;
		}
		if (!vcc->qos.txtp.traffic_class &&
		    !vcc->qos.rxtp.traffic_class) {
			error = -EINVAL;
			goto out;
		}
		vcc->remote = *addr;
		set_bit(ATM_VF_WAITING, &vcc->flags);
		sigd_enq(vcc, as_connect, NULL, NULL, &vcc->remote);
		if (flags & O_NONBLOCK) {
			sock->state = SS_CONNECTING;
			error = -EINPROGRESS;
			goto out;
		}
		error = 0;
		prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
		while (test_bit(ATM_VF_WAITING, &vcc->flags) && sigd) {
			schedule();
			if (!signal_pending(current)) {
				prepare_to_wait(sk_sleep(sk), &wait,
						TASK_INTERRUPTIBLE);
				continue;
			}
			pr_debug("*ABORT*\n");
			/*
			 * This is tricky:
			 *   Kernel ---close--> Demon
			 *   Kernel <--close--- Demon
			 * or
			 *   Kernel ---close--> Demon
			 *   Kernel <--error--- Demon
			 * or
			 *   Kernel ---close--> Demon
			 *   Kernel <--okay---- Demon
			 *   Kernel <--close--- Demon
			 */
			sigd_enq(vcc, as_close, NULL, NULL, NULL);
			while (test_bit(ATM_VF_WAITING, &vcc->flags) && sigd) {
				prepare_to_wait(sk_sleep(sk), &wait,
						TASK_INTERRUPTIBLE);
				schedule();
			}
			if (!sk->sk_err)
				while (!test_bit(ATM_VF_RELEASED, &vcc->flags) &&
				       sigd) {
					prepare_to_wait(sk_sleep(sk), &wait,
							TASK_INTERRUPTIBLE);
					schedule();
				}
			clear_bit(ATM_VF_REGIS, &vcc->flags);
			clear_bit(ATM_VF_RELEASED, &vcc->flags);
			clear_bit(ATM_VF_CLOSE, &vcc->flags);
			    /* we're gone now but may connect later */
			error = -EINTR;
			break;
		}
		finish_wait(sk_sleep(sk), &wait);
		if (error)
			goto out;
		if (!sigd) {
			error = -EUNATCH;
			goto out;
		}
		if (sk->sk_err) {
			error = -sk->sk_err;
			goto out;
		}
	}

	vcc->qos.txtp.max_pcr = SELECT_TOP_PCR(vcc->qos.txtp);
	vcc->qos.txtp.pcr = 0;
	vcc->qos.txtp.min_pcr = 0;

	error = vcc_connect(sock, vcc->itf, vcc->vpi, vcc->vci);
	if (!error)
		sock->state = SS_CONNECTED;
	else
		(void)svc_disconnect(vcc);
out:
	release_sock(sk);
	return error;
}

static int svc_listen(struct socket *sock, int backlog)
{
	DEFINE_WAIT(wait);
	struct sock *sk = sock->sk;
	struct atm_vcc *vcc = ATM_SD(sock);
	int error;

	pr_debug("%p\n", vcc);
	lock_sock(sk);
	/* let server handle listen on unbound sockets */
	if (test_bit(ATM_VF_SESSION, &vcc->flags)) {
		error = -EINVAL;
		goto out;
	}
	if (test_bit(ATM_VF_LISTEN, &vcc->flags)) {
		error = -EADDRINUSE;
		goto out;
	}
	set_bit(ATM_VF_WAITING, &vcc->flags);
	sigd_enq(vcc, as_listen, NULL, NULL, &vcc->local);
	for (;;) {
		prepare_to_wait(sk_sleep(sk), &wait, TASK_UNINTERRUPTIBLE);
		if (!test_bit(ATM_VF_WAITING, &vcc->flags) || !sigd)
			break;
		schedule();
	}
	finish_wait(sk_sleep(sk), &wait);
	if (!sigd) {
		error = -EUNATCH;
		goto out;
	}
	set_bit(ATM_VF_LISTEN, &vcc->flags);
	vcc_insert_socket(sk);
	sk->sk_max_ack_backlog = backlog > 0 ? backlog : ATM_BACKLOG_DEFAULT;
	error = -sk->sk_err;
out:
	release_sock(sk);
	return error;
}

static int svc_accept(struct socket *sock, struct socket *newsock, int flags,
		      bool kern)
{
	struct sock *sk = sock->sk;
	struct sk_buff *skb;
	struct atmsvc_msg *msg;
	struct atm_vcc *old_vcc = ATM_SD(sock);
	struct atm_vcc *new_vcc;
	int error;

	lock_sock(sk);

	error = svc_create(sock_net(sk), newsock, 0, kern);
	if (error)
		goto out;

	new_vcc = ATM_SD(newsock);

	pr_debug("%p -> %p\n", old_vcc, new_vcc);
	while (1) {
		DEFINE_WAIT(wait);

		prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
		while (!(skb = skb_dequeue(&sk->sk_receive_queue)) &&
		       sigd) {
			if (test_bit(ATM_VF_RELEASED, &old_vcc->flags))
				break;
			if (test_bit(ATM_VF_CLOSE, &old_vcc->flags)) {
				error = -sk->sk_err;
				break;
			}
			if (flags & O_NONBLOCK) {
				error = -EAGAIN;
				break;
			}
			release_sock(sk);
			schedule();
			lock_sock(sk);
			if (signal_pending(current)) {
				error = -ERESTARTSYS;
				break;
			}
			prepare_to_wait(sk_sleep(sk), &wait,
					TASK_INTERRUPTIBLE);
		}
		finish_wait(sk_sleep(sk), &wait);
		if (error)
			goto out;
		if (!skb) {
			error = -EUNATCH;
			goto out;
		}
		msg = (struct atmsvc_msg *)skb->data;
		new_vcc->qos = msg->qos;
		set_bit(ATM_VF_HASQOS, &new_vcc->flags);
		new_vcc->remote = msg->svc;
		new_vcc->local = msg->local;
		new_vcc->sap = msg->sap;
		error = vcc_connect(newsock, msg->pvc.sap_addr.itf,
				    msg->pvc.sap_addr.vpi,
				    msg->pvc.sap_addr.vci);
		dev_kfree_skb(skb);
		sk->sk_ack_backlog--;
		if (error) {
			sigd_enq2(NULL, as_reject, old_vcc, NULL, NULL,
				  &old_vcc->qos, error);
			error = error == -EAGAIN ? -EBUSY : error;
			goto out;
		}
		/* wait should be short, so we ignore the non-blocking flag */
		set_bit(ATM_VF_WAITING, &new_vcc->flags);
		sigd_enq(new_vcc, as_accept, old_vcc, NULL, NULL);
		for (;;) {
			prepare_to_wait(sk_sleep(sk_atm(new_vcc)), &wait,
					TASK_UNINTERRUPTIBLE);
			if (!test_bit(ATM_VF_WAITING, &new_vcc->flags) || !sigd)
				break;
			release_sock(sk);
			schedule();
			lock_sock(sk);
		}
		finish_wait(sk_sleep(sk_atm(new_vcc)), &wait);
		if (!sigd) {
			error = -EUNATCH;
			goto out;
		}
		if (!sk_atm(new_vcc)->sk_err)
			break;
		if (sk_atm(new_vcc)->sk_err != ERESTARTSYS) {
			error = -sk_atm(new_vcc)->sk_err;
			goto out;
		}
	}
	newsock->state = SS_CONNECTED;
out:
	release_sock(sk);
	return error;
}

static int svc_getname(struct socket *sock, struct sockaddr *sockaddr,
		       int peer)
{
	struct sockaddr_atmsvc *addr;

	addr = (struct sockaddr_atmsvc *) sockaddr;
	memcpy(addr, peer ? &ATM_SD(sock)->remote : &ATM_SD(sock)->local,
	       sizeof(struct sockaddr_atmsvc));
	return sizeof(struct sockaddr_atmsvc);
}

int svc_change_qos(struct atm_vcc *vcc, struct atm_qos *qos)
{
	struct sock *sk = sk_atm(vcc);
	DEFINE_WAIT(wait);

	set_bit(ATM_VF_WAITING, &vcc->flags);
	sigd_enq2(vcc, as_modify, NULL, NULL, &vcc->local, qos, 0);
	for (;;) {
		prepare_to_wait(sk_sleep(sk), &wait, TASK_UNINTERRUPTIBLE);
		if (!test_bit(ATM_VF_WAITING, &vcc->flags) ||
		    test_bit(ATM_VF_RELEASED, &vcc->flags) || !sigd) {
			break;
		}
		schedule();
	}
	finish_wait(sk_sleep(sk), &wait);
	if (!sigd)
		return -EUNATCH;
	return -sk->sk_err;
}

static int svc_setsockopt(struct socket *sock, int level, int optname,
			  char __user *optval, unsigned int optlen)
{
	struct sock *sk = sock->sk;
	struct atm_vcc *vcc = ATM_SD(sock);
	int value, error = 0;

	lock_sock(sk);
	switch (optname) {
	case SO_ATMSAP:
		if (level != SOL_ATM || optlen != sizeof(struct atm_sap)) {
			error = -EINVAL;
			goto out;
		}
		if (copy_from_user(&vcc->sap, optval, optlen)) {
			error = -EFAULT;
			goto out;
		}
		set_bit(ATM_VF_HASSAP, &vcc->flags);
		break;
	case SO_MULTIPOINT:
		if (level != SOL_ATM || optlen != sizeof(int)) {
			error = -EINVAL;
			goto out;
		}
		if (get_user(value, (int __user *)optval)) {
			error = -EFAULT;
			goto out;
		}
		if (value == 1)
			set_bit(ATM_VF_SESSION, &vcc->flags);
		else if (value == 0)
			clear_bit(ATM_VF_SESSION, &vcc->flags);
		else
			error = -EINVAL;
		break;
	default:
		error = vcc_setsockopt(sock, level, optname, optval, optlen);
	}

out:
	release_sock(sk);
	return error;
}

static int svc_getsockopt(struct socket *sock, int level, int optname,
			  char __user *optval, int __user *optlen)
{
	struct sock *sk = sock->sk;
	int error = 0, len;

	lock_sock(sk);
	if (!__SO_LEVEL_MATCH(optname, level) || optname != SO_ATMSAP) {
		error = vcc_getsockopt(sock, level, optname, optval, optlen);
		goto out;
	}
	if (get_user(len, optlen)) {
		error = -EFAULT;
		goto out;
	}
	if (len != sizeof(struct atm_sap)) {
		error = -EINVAL;
		goto out;
	}
	if (copy_to_user(optval, &ATM_SD(sock)->sap, sizeof(struct atm_sap))) {
		error = -EFAULT;
		goto out;
	}
out:
	release_sock(sk);
	return error;
}

static int svc_addparty(struct socket *sock, struct sockaddr *sockaddr,
			int sockaddr_len, int flags)
{
	DEFINE_WAIT(wait);
	struct sock *sk = sock->sk;
	struct atm_vcc *vcc = ATM_SD(sock);
	int error;

	lock_sock(sk);
	set_bit(ATM_VF_WAITING, &vcc->flags);
	sigd_enq(vcc, as_addparty, NULL, NULL,
		 (struct sockaddr_atmsvc *) sockaddr);
	if (flags & O_NONBLOCK) {
		error = -EINPROGRESS;
		goto out;
	}
	pr_debug("added wait queue\n");
	for (;;) {
		prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
		if (!test_bit(ATM_VF_WAITING, &vcc->flags) || !sigd)
			break;
		schedule();
	}
	finish_wait(sk_sleep(sk), &wait);
	error = -xchg(&sk->sk_err_soft, 0);
out:
	release_sock(sk);
	return error;
}

static int svc_dropparty(struct socket *sock, int ep_ref)
{
	DEFINE_WAIT(wait);
	struct sock *sk = sock->sk;
	struct atm_vcc *vcc = ATM_SD(sock);
	int error;

	lock_sock(sk);
	set_bit(ATM_VF_WAITING, &vcc->flags);
	sigd_enq2(vcc, as_dropparty, NULL, NULL, NULL, NULL, ep_ref);
	for (;;) {
		prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
		if (!test_bit(ATM_VF_WAITING, &vcc->flags) || !sigd)
			break;
		schedule();
	}
	finish_wait(sk_sleep(sk), &wait);
	if (!sigd) {
		error = -EUNATCH;
		goto out;
	}
	error = -xchg(&sk->sk_err_soft, 0);
out:
	release_sock(sk);
	return error;
}

static int svc_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
{
	int error, ep_ref;
	struct sockaddr_atmsvc sa;
	struct atm_vcc *vcc = ATM_SD(sock);

	switch (cmd) {
	case ATM_ADDPARTY:
		if (!test_bit(ATM_VF_SESSION, &vcc->flags))
			return -EINVAL;
		if (copy_from_user(&sa, (void __user *) arg, sizeof(sa)))
			return -EFAULT;
		error = svc_addparty(sock, (struct sockaddr *)&sa, sizeof(sa),
				     0);
		break;
	case ATM_DROPPARTY:
		if (!test_bit(ATM_VF_SESSION, &vcc->flags))
			return -EINVAL;
		if (copy_from_user(&ep_ref, (void __user *) arg, sizeof(int)))
			return -EFAULT;
		error = svc_dropparty(sock, ep_ref);
		break;
	default:
		error = vcc_ioctl(sock, cmd, arg);
	}

	return error;
}

#ifdef CONFIG_COMPAT
static int svc_compat_ioctl(struct socket *sock, unsigned int cmd,
			    unsigned long arg)
{
	/* The definition of ATM_ADDPARTY uses the size of struct atm_iobuf.
	   But actually it takes a struct sockaddr_atmsvc, which doesn't need
	   compat handling. So all we have to do is fix up cmd... */
	if (cmd == COMPAT_ATM_ADDPARTY)
		cmd = ATM_ADDPARTY;

	if (cmd == ATM_ADDPARTY || cmd == ATM_DROPPARTY)
		return svc_ioctl(sock, cmd, arg);
	else
		return vcc_compat_ioctl(sock, cmd, arg);
}
#endif /* CONFIG_COMPAT */

static const struct proto_ops svc_proto_ops = {
	.family =	PF_ATMSVC,
	.owner =	THIS_MODULE,

	.release =	svc_release,
	.bind =		svc_bind,
	.connect =	svc_connect,
	.socketpair =	sock_no_socketpair,
	.accept =	svc_accept,
	.getname =	svc_getname,
	.poll_mask =	vcc_poll_mask,
	.ioctl =	svc_ioctl,
#ifdef CONFIG_COMPAT
	.compat_ioctl =	svc_compat_ioctl,
#endif
	.listen =	svc_listen,
	.shutdown =	svc_shutdown,
	.setsockopt =	svc_setsockopt,
	.getsockopt =	svc_getsockopt,
	.sendmsg =	vcc_sendmsg,
	.recvmsg =	vcc_recvmsg,
	.mmap =		sock_no_mmap,
	.sendpage =	sock_no_sendpage,
};


static int svc_create(struct net *net, struct socket *sock, int protocol,
		      int kern)
{
	int error;

	if (!net_eq(net, &init_net))
		return -EAFNOSUPPORT;

	sock->ops = &svc_proto_ops;
	error = vcc_create(net, sock, protocol, AF_ATMSVC, kern);
	if (error)
		return error;
	ATM_SD(sock)->local.sas_family = AF_ATMSVC;
	ATM_SD(sock)->remote.sas_family = AF_ATMSVC;
	return 0;
}

static const struct net_proto_family svc_family_ops = {
	.family = PF_ATMSVC,
	.create = svc_create,
	.owner = THIS_MODULE,
};


/*
 *	Initialize the ATM SVC protocol family
 */

int __init atmsvc_init(void)
{
	return sock_register(&svc_family_ops);
}

void atmsvc_exit(void)
{
	sock_unregister(PF_ATMSVC);
}