/*
 *  Shared Memory Communications over RDMA (SMC-R) and RoCE
 *
 *  AF_SMC protocol family socket handler keeping the AF_INET sock address type
 *  applies to SOCK_STREAM sockets only
 *  offers an alternative communication option for TCP-protocol sockets
 *  applicable with RoCE-cards only
 *
 *  Copyright IBM Corp. 2016
 *
 *  Author(s):  Ursula Braun <ubraun@linux.vnet.ibm.com>
 *              based on prototype from Frank Blaschka
 */

#define KMSG_COMPONENT "smc"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

#include <linux/module.h>
#include <linux/socket.h>
#include <net/sock.h>

#include "smc.h"

static void smc_set_keepalive(struct sock *sk, int val)
{
	struct smc_sock *smc = smc_sk(sk);

	smc->clcsock->sk->sk_prot->keepalive(smc->clcsock->sk, val);
}

static struct proto smc_proto = {
	.name		= "SMC",
	.owner		= THIS_MODULE,
	.keepalive	= smc_set_keepalive,
	.obj_size	= sizeof(struct smc_sock),
	.slab_flags	= SLAB_DESTROY_BY_RCU,
};

static int smc_release(struct socket *sock)
{
	struct sock *sk = sock->sk;
	struct smc_sock *smc;

	if (!sk)
		goto out;

	smc = smc_sk(sk);
	lock_sock(sk);

	sk->sk_state = SMC_CLOSED;
	if (smc->clcsock) {
		sock_release(smc->clcsock);
		smc->clcsock = NULL;
	}

	/* detach socket */
	sock_orphan(sk);
	sock->sk = NULL;
	release_sock(sk);

	sock_put(sk);
out:
	return 0;
}

static void smc_destruct(struct sock *sk)
{
	if (sk->sk_state != SMC_CLOSED)
		return;
	if (!sock_flag(sk, SOCK_DEAD))
		return;

	sk_refcnt_debug_dec(sk);
}

static struct sock *smc_sock_alloc(struct net *net, struct socket *sock)
{
	struct smc_sock *smc;
	struct sock *sk;

	sk = sk_alloc(net, PF_SMC, GFP_KERNEL, &smc_proto, 0);
	if (!sk)
		return NULL;

	sock_init_data(sock, sk); /* sets sk_refcnt to 1 */
	sk->sk_state = SMC_INIT;
	sk->sk_destruct = smc_destruct;
	sk->sk_protocol = SMCPROTO_SMC;
	sk_refcnt_debug_inc(sk);

	smc = smc_sk(sk);

	return sk;
}

static int smc_bind(struct socket *sock, struct sockaddr *uaddr,
		    int addr_len)
{
	struct sockaddr_in *addr = (struct sockaddr_in *)uaddr;
	struct sock *sk = sock->sk;
	struct smc_sock *smc;
	int rc;

	smc = smc_sk(sk);

	/* replicate tests from inet_bind(), to be safe wrt. future changes */
	rc = -EINVAL;
	if (addr_len < sizeof(struct sockaddr_in))
		goto out;

	rc = -EAFNOSUPPORT;
	/* accept AF_UNSPEC (mapped to AF_INET) only if s_addr is INADDR_ANY */
	if ((addr->sin_family != AF_INET) &&
	    ((addr->sin_family != AF_UNSPEC) ||
	     (addr->sin_addr.s_addr != htonl(INADDR_ANY))))
		goto out;

	lock_sock(sk);

	/* Check if socket is already active */
	rc = -EINVAL;
	if (sk->sk_state != SMC_INIT)
		goto out_rel;

	smc->clcsock->sk->sk_reuse = sk->sk_reuse;
	rc = kernel_bind(smc->clcsock, uaddr, addr_len);

out_rel:
	release_sock(sk);
out:
	return rc;
}

static void smc_copy_sock_settings(struct sock *nsk, struct sock *osk,
				   unsigned long mask)
{
	/* options we don't get control via setsockopt for */
	nsk->sk_type = osk->sk_type;
	nsk->sk_sndbuf = osk->sk_sndbuf;
	nsk->sk_rcvbuf = osk->sk_rcvbuf;
	nsk->sk_sndtimeo = osk->sk_sndtimeo;
	nsk->sk_rcvtimeo = osk->sk_rcvtimeo;
	nsk->sk_mark = osk->sk_mark;
	nsk->sk_priority = osk->sk_priority;
	nsk->sk_rcvlowat = osk->sk_rcvlowat;
	nsk->sk_bound_dev_if = osk->sk_bound_dev_if;
	nsk->sk_err = osk->sk_err;

	nsk->sk_flags &= ~mask;
	nsk->sk_flags |= osk->sk_flags & mask;
}

#define SK_FLAGS_SMC_TO_CLC ((1UL << SOCK_URGINLINE) | \
			     (1UL << SOCK_KEEPOPEN) | \
			     (1UL << SOCK_LINGER) | \
			     (1UL << SOCK_BROADCAST) | \
			     (1UL << SOCK_TIMESTAMP) | \
			     (1UL << SOCK_DBG) | \
			     (1UL << SOCK_RCVTSTAMP) | \
			     (1UL << SOCK_RCVTSTAMPNS) | \
			     (1UL << SOCK_LOCALROUTE) | \
			     (1UL << SOCK_TIMESTAMPING_RX_SOFTWARE) | \
			     (1UL << SOCK_RXQ_OVFL) | \
			     (1UL << SOCK_WIFI_STATUS) | \
			     (1UL << SOCK_NOFCS) | \
			     (1UL << SOCK_FILTER_LOCKED))
/* copy only relevant settings and flags of SOL_SOCKET level from smc to
 * clc socket (since smc is not called for these options from net/core)
 */
static void smc_copy_sock_settings_to_clc(struct smc_sock *smc)
{
	smc_copy_sock_settings(smc->clcsock->sk, &smc->sk, SK_FLAGS_SMC_TO_CLC);
}

#define SK_FLAGS_CLC_TO_SMC ((1UL << SOCK_URGINLINE) | \
			     (1UL << SOCK_KEEPOPEN) | \
			     (1UL << SOCK_LINGER) | \
			     (1UL << SOCK_DBG))
/* copy only settings and flags relevant for smc from clc to smc socket */
static void smc_copy_sock_settings_to_smc(struct smc_sock *smc)
{
	smc_copy_sock_settings(&smc->sk, smc->clcsock->sk, SK_FLAGS_CLC_TO_SMC);
}

static int smc_connect(struct socket *sock, struct sockaddr *addr,
		       int alen, int flags)
{
	struct sock *sk = sock->sk;
	struct smc_sock *smc;
	int rc = -EINVAL;

	smc = smc_sk(sk);

	/* separate smc parameter checking to be safe */
	if (alen < sizeof(addr->sa_family))
		goto out_err;
	if (addr->sa_family != AF_INET)
		goto out_err;

	lock_sock(sk);
	switch (sk->sk_state) {
	default:
		goto out;
	case SMC_ACTIVE:
		rc = -EISCONN;
		goto out;
	case SMC_INIT:
		rc = 0;
		break;
	}

	smc_copy_sock_settings_to_clc(smc);
	rc = kernel_connect(smc->clcsock, addr, alen, flags);
	if (rc)
		goto out;

	sk->sk_state = SMC_ACTIVE;

	/* always use TCP fallback as transport mechanism for now;
	 * This will change once RDMA transport is implemented
	 */
	smc->use_fallback = true;

out:
	release_sock(sk);
out_err:
	return rc;
}

static int smc_clcsock_accept(struct smc_sock *lsmc, struct smc_sock **new_smc)
{
	struct sock *sk = &lsmc->sk;
	struct socket *new_clcsock;
	struct sock *new_sk;
	int rc;

	new_sk = smc_sock_alloc(sock_net(sk), NULL);
	if (!new_sk) {
		rc = -ENOMEM;
		lsmc->sk.sk_err = ENOMEM;
		*new_smc = NULL;
		goto out;
	}
	*new_smc = smc_sk(new_sk);

	rc = kernel_accept(lsmc->clcsock, &new_clcsock, 0);
	if (rc) {
		sock_put(new_sk);
		*new_smc = NULL;
		goto out;
	}

	(*new_smc)->clcsock = new_clcsock;
out:
	return rc;
}

static int smc_listen(struct socket *sock, int backlog)
{
	struct sock *sk = sock->sk;
	struct smc_sock *smc;
	int rc;

	smc = smc_sk(sk);
	lock_sock(sk);

	rc = -EINVAL;
	if ((sk->sk_state != SMC_INIT) && (sk->sk_state != SMC_LISTEN))
		goto out;

	rc = 0;
	if (sk->sk_state == SMC_LISTEN) {
		sk->sk_max_ack_backlog = backlog;
		goto out;
	}
	/* some socket options are handled in core, so we could not apply
	 * them to the clc socket -- copy smc socket options to clc socket
	 */
	smc_copy_sock_settings_to_clc(smc);

	rc = kernel_listen(smc->clcsock, backlog);
	if (rc)
		goto out;
	sk->sk_max_ack_backlog = backlog;
	sk->sk_ack_backlog = 0;
	sk->sk_state = SMC_LISTEN;

out:
	release_sock(sk);
	return rc;
}

static int smc_accept(struct socket *sock, struct socket *new_sock,
		      int flags)
{
	struct smc_sock *new_smc;
	struct sock *sk = sock->sk;
	struct smc_sock *lsmc;
	int rc;

	lsmc = smc_sk(sk);
	lock_sock(sk);

	if (lsmc->sk.sk_state != SMC_LISTEN) {
		rc = -EINVAL;
		goto out;
	}

	rc = smc_clcsock_accept(lsmc, &new_smc);
	if (rc)
		goto out;
	sock_graft(&new_smc->sk, new_sock);
	new_smc->sk.sk_state = SMC_ACTIVE;

	smc_copy_sock_settings_to_smc(new_smc);

	/* always use TCP fallback as transport mechanism for now;
	 * This will change once RDMA transport is implemented
	 */
	new_smc->use_fallback = true;

out:
	release_sock(sk);
	return rc;
}

static int smc_getname(struct socket *sock, struct sockaddr *addr,
		       int *len, int peer)
{
	struct smc_sock *smc;

	if (peer && (sock->sk->sk_state != SMC_ACTIVE))
		return -ENOTCONN;

	smc = smc_sk(sock->sk);

	return smc->clcsock->ops->getname(smc->clcsock, addr, len, peer);
}

static int smc_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
{
	struct sock *sk = sock->sk;
	struct smc_sock *smc;
	int rc = -EPIPE;

	smc = smc_sk(sk);
	lock_sock(sk);
	if (sk->sk_state != SMC_ACTIVE)
		goto out;
	if (smc->use_fallback)
		rc = smc->clcsock->ops->sendmsg(smc->clcsock, msg, len);
	else
		rc = sock_no_sendmsg(sock, msg, len);
out:
	release_sock(sk);
	return rc;
}

static int smc_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
		       int flags)
{
	struct sock *sk = sock->sk;
	struct smc_sock *smc;
	int rc = -ENOTCONN;

	smc = smc_sk(sk);
	lock_sock(sk);
	if ((sk->sk_state != SMC_ACTIVE) && (sk->sk_state != SMC_CLOSED))
		goto out;

	if (smc->use_fallback)
		rc = smc->clcsock->ops->recvmsg(smc->clcsock, msg, len, flags);
	else
		rc = sock_no_recvmsg(sock, msg, len, flags);
out:
	release_sock(sk);
	return rc;
}

static unsigned int smc_poll(struct file *file, struct socket *sock,
			     poll_table *wait)
{
	struct sock *sk = sock->sk;
	unsigned int mask = 0;
	struct smc_sock *smc;

	smc = smc_sk(sock->sk);
	if ((sk->sk_state == SMC_INIT) || (sk->sk_state == SMC_LISTEN) ||
	    smc->use_fallback) {
		mask = smc->clcsock->ops->poll(file, smc->clcsock, wait);
		/* if non-blocking connect finished ... */
		lock_sock(sk);
		if ((sk->sk_state == SMC_INIT) && (mask & POLLOUT)) {
			sk->sk_state = SMC_ACTIVE;
			/* always use TCP fallback as transport mechanism;
			 * This will change once RDMA transport is implemented
			 */
			smc->use_fallback = true;
		}
		release_sock(sk);
	} else {
		mask = sock_no_poll(file, sock, wait);
	}

	return mask;
}

static int smc_shutdown(struct socket *sock, int how)
{
	struct sock *sk = sock->sk;
	struct smc_sock *smc;
	int rc = -EINVAL;

	smc = smc_sk(sk);

	if ((how < SHUT_RD) || (how > SHUT_RDWR))
		goto out_err;

	lock_sock(sk);

	rc = -ENOTCONN;
	if (sk->sk_state == SMC_CLOSED)
		goto out;
	if (smc->use_fallback) {
		rc = kernel_sock_shutdown(smc->clcsock, how);
		sk->sk_shutdown = smc->clcsock->sk->sk_shutdown;
		if (sk->sk_shutdown == SHUTDOWN_MASK)
			sk->sk_state = SMC_CLOSED;
	} else {
		rc = sock_no_shutdown(sock, how);
	}

out:
	release_sock(sk);

out_err:
	return rc;
}

static int smc_setsockopt(struct socket *sock, int level, int optname,
			  char __user *optval, unsigned int optlen)
{
	struct sock *sk = sock->sk;
	struct smc_sock *smc;

	smc = smc_sk(sk);

	/* generic setsockopts reaching us here always apply to the
	 * CLC socket
	 */
	return smc->clcsock->ops->setsockopt(smc->clcsock, level, optname,
					     optval, optlen);
}

static int smc_getsockopt(struct socket *sock, int level, int optname,
			  char __user *optval, int __user *optlen)
{
	struct smc_sock *smc;

	smc = smc_sk(sock->sk);
	/* socket options apply to the CLC socket */
	return smc->clcsock->ops->getsockopt(smc->clcsock, level, optname,
					     optval, optlen);
}

static int smc_ioctl(struct socket *sock, unsigned int cmd,
		     unsigned long arg)
{
	struct smc_sock *smc;

	smc = smc_sk(sock->sk);
	if (smc->use_fallback)
		return smc->clcsock->ops->ioctl(smc->clcsock, cmd, arg);
	else
		return sock_no_ioctl(sock, cmd, arg);
}

static ssize_t smc_sendpage(struct socket *sock, struct page *page,
			    int offset, size_t size, int flags)
{
	struct sock *sk = sock->sk;
	struct smc_sock *smc;
	int rc = -EPIPE;

	smc = smc_sk(sk);
	lock_sock(sk);
	if (sk->sk_state != SMC_ACTIVE)
		goto out;
	if (smc->use_fallback)
		rc = kernel_sendpage(smc->clcsock, page, offset,
				     size, flags);
	else
		rc = sock_no_sendpage(sock, page, offset, size, flags);

out:
	release_sock(sk);
	return rc;
}

static ssize_t smc_splice_read(struct socket *sock, loff_t *ppos,
			       struct pipe_inode_info *pipe, size_t len,
				    unsigned int flags)
{
	struct sock *sk = sock->sk;
	struct smc_sock *smc;
	int rc = -ENOTCONN;

	smc = smc_sk(sk);
	lock_sock(sk);
	if ((sk->sk_state != SMC_ACTIVE) && (sk->sk_state != SMC_CLOSED))
		goto out;
	if (smc->use_fallback) {
		rc = smc->clcsock->ops->splice_read(smc->clcsock, ppos,
						    pipe, len, flags);
	} else {
		rc = -EOPNOTSUPP;
	}
out:
	release_sock(sk);
	return rc;
}

/* must look like tcp */
static const struct proto_ops smc_sock_ops = {
	.family		= PF_SMC,
	.owner		= THIS_MODULE,
	.release	= smc_release,
	.bind		= smc_bind,
	.connect	= smc_connect,
	.socketpair	= sock_no_socketpair,
	.accept		= smc_accept,
	.getname	= smc_getname,
	.poll		= smc_poll,
	.ioctl		= smc_ioctl,
	.listen		= smc_listen,
	.shutdown	= smc_shutdown,
	.setsockopt	= smc_setsockopt,
	.getsockopt	= smc_getsockopt,
	.sendmsg	= smc_sendmsg,
	.recvmsg	= smc_recvmsg,
	.mmap		= sock_no_mmap,
	.sendpage	= smc_sendpage,
	.splice_read	= smc_splice_read,
};

static int smc_create(struct net *net, struct socket *sock, int protocol,
		      int kern)
{
	struct smc_sock *smc;
	struct sock *sk;
	int rc;

	rc = -ESOCKTNOSUPPORT;
	if (sock->type != SOCK_STREAM)
		goto out;

	rc = -EPROTONOSUPPORT;
	if ((protocol != IPPROTO_IP) && (protocol != IPPROTO_TCP))
		goto out;

	rc = -ENOBUFS;
	sock->ops = &smc_sock_ops;
	sk = smc_sock_alloc(net, sock);
	if (!sk)
		goto out;

	/* create internal TCP socket for CLC handshake and fallback */
	smc = smc_sk(sk);
	rc = sock_create_kern(net, PF_INET, SOCK_STREAM,
			      IPPROTO_TCP, &smc->clcsock);
	if (rc)
		sk_common_release(sk);

out:
	return rc;
}

static const struct net_proto_family smc_sock_family_ops = {
	.family	= PF_SMC,
	.owner	= THIS_MODULE,
	.create	= smc_create,
};

static int __init smc_init(void)
{
	int rc;

	rc = proto_register(&smc_proto, 1);
	if (rc) {
		pr_err("%s: proto_register fails with %d\n", __func__, rc);
		goto out;
	}

	rc = sock_register(&smc_sock_family_ops);
	if (rc) {
		pr_err("%s: sock_register fails with %d\n", __func__, rc);
		goto out_proto;
	}

	return 0;

out_proto:
	proto_unregister(&smc_proto);
out:
	return rc;
}

static void __exit smc_exit(void)
{
	sock_unregister(PF_SMC);
	proto_unregister(&smc_proto);
}

module_init(smc_init);
module_exit(smc_exit);

MODULE_AUTHOR("Ursula Braun <ubraun@linux.vnet.ibm.com>");
MODULE_DESCRIPTION("smc socket address family");
MODULE_LICENSE("GPL");
MODULE_ALIAS_NETPROTO(PF_SMC);