1 files changed, 689 insertions, 0 deletions

diff --git a/sys/netlink/netlink_domain.c b/sys/netlink/netlink_domain.c
new file mode 100644
index 000000000000..159dfd03724d
--- /dev/null
+++ b/sys/netlink/netlink_domain.c
@@ -0,0 +1,689 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
+ * Copyright (c) 2021 Ng Peng Nam Sean
+ * Copyright (c) 2022 Alexander V. Chernikov <melifaro@FreeBSD.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+/*
+ * This file contains socket and protocol bindings for netlink.
+ */
+
+#include <sys/param.h>
+#include <sys/malloc.h>
+#include <sys/lock.h>
+#include <sys/rmlock.h>
+#include <sys/domain.h>
+#include <sys/mbuf.h>
+#include <sys/protosw.h>
+#include <sys/ck.h>
+#include <sys/socket.h>
+#include <sys/socketvar.h>
+#include <sys/sysent.h>
+#include <sys/syslog.h>
+#include <sys/priv.h> /* priv_check */
+
+#include <netlink/netlink.h>
+#include <netlink/netlink_ctl.h>
+#include <netlink/netlink_var.h>
+
+#define	DEBUG_MOD_NAME	nl_domain
+#define	DEBUG_MAX_LEVEL	LOG_DEBUG3
+#include <netlink/netlink_debug.h>
+_DECLARE_DEBUG(LOG_DEBUG);
+
+
+#define	NLCTL_TRACKER		struct rm_priotracker nl_tracker
+#define	NLCTL_RLOCK(_ctl)	rm_rlock(&((_ctl)->ctl_lock), &nl_tracker)
+#define	NLCTL_RUNLOCK(_ctl)	rm_runlock(&((_ctl)->ctl_lock), &nl_tracker)
+
+#define	NLCTL_WLOCK(_ctl)	rm_wlock(&((_ctl)->ctl_lock))
+#define	NLCTL_WUNLOCK(_ctl)	rm_wunlock(&((_ctl)->ctl_lock))
+
+static u_long nl_sendspace = NLSNDQ;
+SYSCTL_ULONG(_net_netlink, OID_AUTO, sendspace, CTLFLAG_RW, &nl_sendspace, 0,
+    "Default netlink socket send space");
+
+static u_long nl_recvspace = NLSNDQ;
+SYSCTL_ULONG(_net_netlink, OID_AUTO, recvspace, CTLFLAG_RW, &nl_recvspace, 0,
+    "Default netlink socket receive space");
+
+extern u_long sb_max_adj;
+static u_long nl_maxsockbuf = 512 * 1024 * 1024; /* 512M, XXX: init based on physmem */
+
+uint32_t
+nlp_get_pid(const struct nlpcb *nlp)
+{
+	return (nlp->nl_process_id);
+}
+
+/*
+ * Looks up a nlpcb struct based on the @portid. Need to claim nlsock_mtx.
+ * Returns nlpcb pointer if present else NULL
+ */
+static struct nlpcb *
+nl_port_lookup(uint32_t port_id)
+{
+	struct nlpcb *nlp;
+
+	CK_LIST_FOREACH(nlp, &V_nl_ctl->ctl_port_head, nl_port_next) {
+		if (nlp->nl_port == port_id)
+			return (nlp);
+	}
+	return (NULL);
+}
+
+static void
+nl_update_groups_locked(struct nlpcb *nlp, uint64_t nl_groups)
+{
+	/* Update group mask */
+	NL_LOG(LOG_DEBUG2, "socket %p, groups 0x%lX -> 0x%lX",
+	    nlp->nl_socket, nlp->nl_groups, nl_groups);
+	nlp->nl_groups = nl_groups;
+}
+
+/*
+ * Broadcasts message @m to the protocol @proto group specified by @group_id
+ */
+void
+nl_send_group(struct mbuf *m, int num_messages, int proto, int group_id)
+{
+	struct nlpcb *nlp_last = NULL;
+	struct nlpcb *nlp;
+	NLCTL_TRACKER;
+
+	IF_DEBUG_LEVEL(LOG_DEBUG2) {
+		struct nlmsghdr *hdr = mtod(m, struct nlmsghdr *);
+		NL_LOG(LOG_DEBUG2, "MCAST mbuf len %u msg type %d len %u to group %d/%d",
+		    m->m_len, hdr->nlmsg_type, hdr->nlmsg_len, proto, group_id);
+	}
+
+	struct nl_control *ctl = atomic_load_ptr(&V_nl_ctl);
+	if (__predict_false(ctl == NULL)) {
+		/*
+		 * Can be the case when notification is sent within VNET
+		 * which doesn't have any netlink sockets.
+		 */
+		m_freem(m);
+		return;
+	}
+
+	NLCTL_RLOCK(ctl);
+
+	int io_flags = NL_IOF_UNTRANSLATED;
+	uint64_t groups_mask = 1 << ((uint64_t)group_id - 1);
+
+	CK_LIST_FOREACH(nlp, &ctl->ctl_pcb_head, nl_next) {
+		if (nlp->nl_groups & groups_mask && nlp->nl_proto == proto) {
+			if (nlp_last != NULL) {
+				struct mbuf *m_copy;
+				m_copy = m_copym(m, 0, M_COPYALL, M_NOWAIT);
+				if (m_copy != NULL)
+					nl_send_one(m_copy, nlp_last, num_messages, io_flags);
+				else {
+					NLP_LOCK(nlp_last);
+					if (nlp_last->nl_socket != NULL)
+						sorwakeup(nlp_last->nl_socket);
+					NLP_UNLOCK(nlp_last);
+				}
+			}
+			nlp_last = nlp;
+		}
+	}
+	if (nlp_last != NULL)
+		nl_send_one(m, nlp_last, num_messages, io_flags);
+	else
+		m_freem(m);
+
+	NLCTL_RUNLOCK(ctl);
+}
+
+bool
+nl_has_listeners(int netlink_family, uint32_t groups_mask)
+{
+	return (V_nl_ctl != NULL);
+}
+
+bool
+nlp_has_priv(struct nlpcb *nlp, int priv)
+{
+	return (priv_check_cred(nlp->nl_cred, priv) == 0);
+}
+
+static uint32_t
+nl_find_port() {
+	/*
+	 * app can open multiple netlink sockets.
+	 * Start with current pid, if already taken,
+	 * try random numbers in 65k..256k+65k space,
+	 * avoiding clash with pids.
+	 */
+	if (nl_port_lookup(curproc->p_pid) == NULL)
+		return (curproc->p_pid);
+	for (int i = 0; i < 16; i++) {
+		uint32_t nl_port = (arc4random() % 65536) + 65536 * 4;
+		if (nl_port_lookup(nl_port) == 0)
+			return (nl_port);
+		NL_LOG(LOG_DEBUG3, "tried %u\n", nl_port);
+	}
+	return (curproc->p_pid);
+}
+
+static int
+nl_bind_locked(struct nlpcb *nlp, struct sockaddr_nl *snl)
+{
+	if (nlp->nl_bound) {
+		if (nlp->nl_port != snl->nl_pid) {
+			NL_LOG(LOG_DEBUG,
+			    "bind() failed: program pid %d "
+			    "is different from provided pid %d",
+			    nlp->nl_port, snl->nl_pid);
+			return (EINVAL); // XXX: better error
+		}
+	} else {
+		if (snl->nl_pid == 0)
+			snl->nl_pid = nl_find_port();
+		if (nl_port_lookup(snl->nl_pid) != NULL)
+			return (EADDRINUSE);
+		nlp->nl_port = snl->nl_pid;
+		nlp->nl_bound = true;
+		CK_LIST_INSERT_HEAD(&V_nl_ctl->ctl_port_head, nlp, nl_port_next);
+	}
+	nl_update_groups_locked(nlp, snl->nl_groups);
+
+	return (0);
+}
+
+static int
+nl_pru_attach(struct socket *so, int proto, struct thread *td)
+{
+	struct nlpcb *nlp;
+	int error;
+
+	if (__predict_false(netlink_unloading != 0))
+		return (EAFNOSUPPORT);
+
+	error = nl_verify_proto(proto);
+	if (error != 0)
+		return (error);
+
+	bool is_linux = SV_PROC_ABI(td->td_proc) == SV_ABI_LINUX;
+	NL_LOG(LOG_DEBUG2, "socket %p, %sPID %d: attaching socket to %s",
+	    so, is_linux ? "(linux) " : "", curproc->p_pid,
+	    nl_get_proto_name(proto));
+
+	/* Create per-VNET state on first socket init */
+	struct nl_control *ctl = atomic_load_ptr(&V_nl_ctl);
+	if (ctl == NULL)
+		ctl = vnet_nl_ctl_init();
+	KASSERT(V_nl_ctl != NULL, ("nl_attach: vnet_sock_init() failed"));
+
+	MPASS(sotonlpcb(so) == NULL);
+
+	nlp = malloc(sizeof(struct nlpcb), M_PCB, M_WAITOK | M_ZERO);
+	error = soreserve(so, nl_sendspace, nl_recvspace);
+	if (error != 0) {
+		free(nlp, M_PCB);
+		return (error);
+	}
+	so->so_pcb = nlp;
+	nlp->nl_socket = so;
+	/* Copy so_cred to avoid having socket_var.h in every header */
+	nlp->nl_cred = so->so_cred;
+	nlp->nl_proto = proto;
+	nlp->nl_process_id = curproc->p_pid;
+	nlp->nl_linux = is_linux;
+	nlp->nl_active = true;
+	NLP_LOCK_INIT(nlp);
+	refcount_init(&nlp->nl_refcount, 1);
+	nl_init_io(nlp);
+
+	nlp->nl_taskqueue = taskqueue_create("netlink_socket", M_WAITOK,
+	    taskqueue_thread_enqueue, &nlp->nl_taskqueue);
+	TASK_INIT(&nlp->nl_task, 0, nl_taskqueue_handler, nlp);
+	taskqueue_start_threads(&nlp->nl_taskqueue, 1, PWAIT,
+	    "netlink_socket (PID %u)", nlp->nl_process_id);
+
+	NLCTL_WLOCK(ctl);
+	/* XXX: check ctl is still alive */
+	CK_LIST_INSERT_HEAD(&ctl->ctl_pcb_head, nlp, nl_next);
+	NLCTL_WUNLOCK(ctl);
+
+	soisconnected(so);
+
+	return (0);
+}
+
+static void
+nl_pru_abort(struct socket *so)
+{
+	NL_LOG(LOG_DEBUG3, "socket %p, PID %d", so, curproc->p_pid);
+	MPASS(sotonlpcb(so) != NULL);
+	soisdisconnected(so);
+}
+
+static int
+nl_pru_bind(struct socket *so, struct sockaddr *sa, struct thread *td)
+{
+	struct nl_control *ctl = atomic_load_ptr(&V_nl_ctl);
+	struct nlpcb *nlp = sotonlpcb(so);
+	struct sockaddr_nl *snl = (struct sockaddr_nl *)sa;
+	int error;
+
+	NL_LOG(LOG_DEBUG3, "socket %p, PID %d", so, curproc->p_pid);
+	if (snl->nl_len != sizeof(*snl)) {
+		NL_LOG(LOG_DEBUG, "socket %p, wrong sizeof(), ignoring bind()", so);
+		return (EINVAL);
+	}
+
+
+	NLCTL_WLOCK(ctl);
+	NLP_LOCK(nlp);
+	error = nl_bind_locked(nlp, snl);
+	NLP_UNLOCK(nlp);
+	NLCTL_WUNLOCK(ctl);
+	NL_LOG(LOG_DEBUG2, "socket %p, bind() to %u, groups %u, error %d", so,
+	    snl->nl_pid, snl->nl_groups, error);
+
+	return (error);
+}
+
+
+static int
+nl_assign_port(struct nlpcb *nlp, uint32_t port_id)
+{
+	struct nl_control *ctl = atomic_load_ptr(&V_nl_ctl);
+	struct sockaddr_nl snl = {
+		.nl_pid = port_id,
+	};
+	int error;
+
+	NLCTL_WLOCK(ctl);
+	NLP_LOCK(nlp);
+	snl.nl_groups = nlp->nl_groups;
+	error = nl_bind_locked(nlp, &snl);
+	NLP_UNLOCK(nlp);
+	NLCTL_WUNLOCK(ctl);
+
+	NL_LOG(LOG_DEBUG3, "socket %p, port assign: %d, error: %d", nlp->nl_socket, port_id, error);
+	return (error);
+}
+
+/*
+ * nl_autobind_port binds a unused portid to @nlp
+ * @nlp: pcb data for the netlink socket
+ * @candidate_id: first id to consider
+ */
+static int
+nl_autobind_port(struct nlpcb *nlp, uint32_t candidate_id)
+{
+	struct nl_control *ctl = atomic_load_ptr(&V_nl_ctl);
+	uint32_t port_id = candidate_id;
+	NLCTL_TRACKER;
+	bool exist;
+	int error;
+
+	for (int i = 0; i < 10; i++) {
+		NL_LOG(LOG_DEBUG3, "socket %p, trying to assign port %d", nlp->nl_socket, port_id);
+		NLCTL_RLOCK(ctl);
+		exist = nl_port_lookup(port_id) != 0;
+		NLCTL_RUNLOCK(ctl);
+		if (!exist) {
+			error = nl_assign_port(nlp, port_id);
+			if (error != EADDRINUSE)
+				break;
+		}
+		port_id++;
+	}
+	NL_LOG(LOG_DEBUG3, "socket %p, autobind to %d, error: %d", nlp->nl_socket, port_id, error);
+	return (error);
+}
+
+static int
+nl_pru_connect(struct socket *so, struct sockaddr *sa, struct thread *td)
+{
+	struct sockaddr_nl *snl = (struct sockaddr_nl *)sa;
+	struct nlpcb *nlp;
+
+	NL_LOG(LOG_DEBUG3, "socket %p, PID %d", so, curproc->p_pid);
+	if (snl->nl_len != sizeof(*snl)) {
+		NL_LOG(LOG_DEBUG, "socket %p, wrong sizeof(), ignoring bind()", so);
+		return (EINVAL);
+	}
+
+	nlp = sotonlpcb(so);
+	if (!nlp->nl_bound) {
+		int error = nl_autobind_port(nlp, td->td_proc->p_pid);
+		if (error != 0) {
+			NL_LOG(LOG_DEBUG, "socket %p, nl_autobind() failed: %d", so, error);
+			return (error);
+		}
+	}
+	/* XXX: Handle socket flags & multicast */
+	soisconnected(so);
+
+	NL_LOG(LOG_DEBUG2, "socket %p, connect to %u", so, snl->nl_pid);
+
+	return (0);
+}
+
+static void
+destroy_nlpcb(struct nlpcb *nlp)
+{
+	NLP_LOCK(nlp);
+	nl_free_io(nlp);
+	NLP_LOCK_DESTROY(nlp);
+	free(nlp, M_PCB);
+}
+
+static void
+destroy_nlpcb_epoch(epoch_context_t ctx)
+{
+	struct nlpcb *nlp;
+
+	nlp = __containerof(ctx, struct nlpcb, nl_epoch_ctx);
+
+	destroy_nlpcb(nlp);
+}
+
+
+static void
+nl_pru_detach(struct socket *so)
+{
+	struct nl_control *ctl = atomic_load_ptr(&V_nl_ctl);
+	MPASS(sotonlpcb(so) != NULL);
+	struct nlpcb *nlp;
+
+	NL_LOG(LOG_DEBUG2, "detaching socket %p, PID %d", so, curproc->p_pid);
+	nlp = sotonlpcb(so);
+
+	/* Mark as inactive so no new work can be enqueued */
+	NLP_LOCK(nlp);
+	bool was_bound = nlp->nl_bound;
+	nlp->nl_active = false;
+	NLP_UNLOCK(nlp);
+
+	/* Wait till all scheduled work has been completed  */
+	taskqueue_drain_all(nlp->nl_taskqueue);
+	taskqueue_free(nlp->nl_taskqueue);
+
+	NLCTL_WLOCK(ctl);
+	NLP_LOCK(nlp);
+	if (was_bound) {
+		CK_LIST_REMOVE(nlp, nl_port_next);
+		NL_LOG(LOG_DEBUG3, "socket %p, unlinking bound pid %u", so, nlp->nl_port);
+	}
+	CK_LIST_REMOVE(nlp, nl_next);
+	nlp->nl_socket = NULL;
+	NLP_UNLOCK(nlp);
+	NLCTL_WUNLOCK(ctl);
+
+	so->so_pcb = NULL;
+
+	NL_LOG(LOG_DEBUG3, "socket %p, detached", so);
+
+	/* XXX: is delayed free needed? */
+	epoch_call(net_epoch_preempt, destroy_nlpcb_epoch, &nlp->nl_epoch_ctx);
+}
+
+static int
+nl_pru_disconnect(struct socket *so)
+{
+	NL_LOG(LOG_DEBUG3, "socket %p, PID %d", so, curproc->p_pid);
+	MPASS(sotonlpcb(so) != NULL);
+	return (ENOTCONN);
+}
+
+static int
+nl_pru_peeraddr(struct socket *so, struct sockaddr **sa)
+{
+	NL_LOG(LOG_DEBUG3, "socket %p, PID %d", so, curproc->p_pid);
+	MPASS(sotonlpcb(so) != NULL);
+	return (ENOTCONN);
+}
+
+static int
+nl_pru_shutdown(struct socket *so)
+{
+	NL_LOG(LOG_DEBUG3, "socket %p, PID %d", so, curproc->p_pid);
+	MPASS(sotonlpcb(so) != NULL);
+	socantsendmore(so);
+	return (0);
+}
+
+static int
+nl_pru_sockaddr(struct socket *so, struct sockaddr **sa)
+{
+	struct sockaddr_nl *snl;
+
+	snl = malloc(sizeof(struct sockaddr_nl), M_SONAME, M_WAITOK | M_ZERO);
+	/* TODO: set other fields */
+	snl->nl_len = sizeof(struct sockaddr_nl);
+	snl->nl_family = AF_NETLINK;
+	snl->nl_pid = sotonlpcb(so)->nl_port;
+	*sa = (struct sockaddr *)snl;
+	return (0);
+}
+
+static void
+nl_pru_close(struct socket *so)
+{
+	NL_LOG(LOG_DEBUG3, "socket %p, PID %d", so, curproc->p_pid);
+	MPASS(sotonlpcb(so) != NULL);
+	soisdisconnected(so);
+}
+
+static int
+nl_pru_output(struct mbuf *m, struct socket *so, ...)
+{
+
+	if (__predict_false(m == NULL ||
+	    ((m->m_len < sizeof(struct nlmsghdr)) &&
+		(m = m_pullup(m, sizeof(struct nlmsghdr))) == NULL)))
+		return (ENOBUFS);
+	MPASS((m->m_flags & M_PKTHDR) != 0);
+
+	NL_LOG(LOG_DEBUG3, "sending message to kernel async processing");
+	nl_receive_async(m, so);
+	return (0);
+}
+
+
+static int
+nl_pru_send(struct socket *so, int flags, struct mbuf *m, struct sockaddr *sa,
+    struct mbuf *control, struct thread *td)
+{
+        NL_LOG(LOG_DEBUG2, "sending message to kernel");
+
+	if (__predict_false(control != NULL)) {
+		if (control->m_len) {
+			m_freem(control);
+			return (EINVAL);
+		}
+		m_freem(control);
+	}
+
+	return (nl_pru_output(m, so));
+}
+
+static int
+nl_pru_rcvd(struct socket *so, int flags)
+{
+	NL_LOG(LOG_DEBUG3, "socket %p, PID %d", so, curproc->p_pid);
+	MPASS(sotonlpcb(so) != NULL);
+
+	nl_on_transmit(sotonlpcb(so));
+
+	return (0);
+}
+
+static int
+nl_getoptflag(int sopt_name)
+{
+	switch (sopt_name) {
+	case NETLINK_CAP_ACK:
+		return (NLF_CAP_ACK);
+	case NETLINK_EXT_ACK:
+		return (NLF_EXT_ACK);
+	case NETLINK_GET_STRICT_CHK:
+		return (NLF_STRICT);
+	}
+
+	return (0);
+}
+
+static int
+nl_ctloutput(struct socket *so, struct sockopt *sopt)
+{
+	struct nl_control *ctl = atomic_load_ptr(&V_nl_ctl);
+	struct nlpcb *nlp = sotonlpcb(so);
+	uint32_t flag;
+	uint64_t groups, group_mask;
+	int optval, error = 0;
+	NLCTL_TRACKER;
+
+	NL_LOG(LOG_DEBUG2, "%ssockopt(%p, %d)", (sopt->sopt_dir) ? "set" : "get",
+	    so, sopt->sopt_name);
+
+	switch (sopt->sopt_dir) {
+	case SOPT_SET:
+		switch (sopt->sopt_name) {
+		case NETLINK_ADD_MEMBERSHIP:
+		case NETLINK_DROP_MEMBERSHIP:
+			sooptcopyin(sopt, &optval, sizeof(optval), sizeof(optval));
+			if (optval <= 0 || optval >= 64) {
+				error = ERANGE;
+				break;
+			}
+			group_mask = (uint64_t)1 << (optval - 1);
+			NL_LOG(LOG_DEBUG2, "ADD/DEL group %d mask (%lX)", optval, group_mask);
+
+			NLCTL_WLOCK(ctl);
+			if (sopt->sopt_name == NETLINK_ADD_MEMBERSHIP)
+				groups = nlp->nl_groups | group_mask;
+			else
+				groups = nlp->nl_groups & ~group_mask;
+			nl_update_groups_locked(nlp, groups);
+			NLCTL_WUNLOCK(ctl);
+			break;
+		case NETLINK_CAP_ACK:
+		case NETLINK_EXT_ACK:
+		case NETLINK_GET_STRICT_CHK:
+			sooptcopyin(sopt, &optval, sizeof(optval), sizeof(optval));
+
+			flag = nl_getoptflag(sopt->sopt_name);
+
+			NLCTL_WLOCK(ctl);
+			if (optval != 0)
+				nlp->nl_flags |= flag;
+			else
+				nlp->nl_flags &= ~flag;
+			NLCTL_WUNLOCK(ctl);
+			break;
+		default:
+			error = ENOPROTOOPT;
+		}
+		break;
+	case SOPT_GET:
+		switch (sopt->sopt_name) {
+		case NETLINK_LIST_MEMBERSHIPS:
+			NLCTL_RLOCK(ctl);
+			optval = nlp->nl_groups;
+			NLCTL_RUNLOCK(ctl);
+			error = sooptcopyout(sopt, &optval, sizeof(optval));
+			break;
+		case NETLINK_CAP_ACK:
+		case NETLINK_EXT_ACK:
+		case NETLINK_GET_STRICT_CHK:
+			NLCTL_RLOCK(ctl);
+			optval = (nlp->nl_flags & nl_getoptflag(sopt->sopt_name)) != 0;
+			NLCTL_RUNLOCK(ctl);
+			error = sooptcopyout(sopt, &optval, sizeof(optval));
+			break;
+		default:
+			error = ENOPROTOOPT;
+		}
+		break;
+	default:
+		error = ENOPROTOOPT;
+	}
+
+	return (error);
+}
+
+static int
+nl_setsbopt(struct socket *so, struct sockopt *sopt)
+{
+	int error, optval;
+	bool result;
+
+	if (sopt->sopt_name != SO_RCVBUF)
+		return (sbsetopt(so, sopt));
+
+	/* Allow to override max buffer size in certain conditions */
+
+	error = sooptcopyin(sopt, &optval, sizeof optval, sizeof optval);
+	if (error != 0)
+		return (error);
+	NL_LOG(LOG_DEBUG2, "socket %p, PID %d, SO_RCVBUF=%d", so, curproc->p_pid, optval);
+	if (optval > sb_max_adj) {
+		if (priv_check(curthread, PRIV_NET_ROUTE) != 0)
+			return (EPERM);
+	}
+
+	SOCK_RECVBUF_LOCK(so);
+	result = sbreserve_locked_limit(so, SO_RCV, optval, nl_maxsockbuf, curthread);
+	SOCK_RECVBUF_UNLOCK(so);
+
+	return (result ? 0 : ENOBUFS);
+}
+
+static struct protosw netlinksw = {
+	.pr_type = SOCK_RAW,
+	.pr_flags = PR_ATOMIC | PR_ADDR | PR_WANTRCVD,
+	.pr_ctloutput = nl_ctloutput,
+	.pr_setsbopt = nl_setsbopt,
+	.pr_abort = nl_pru_abort,
+	.pr_attach = nl_pru_attach,
+	.pr_bind = nl_pru_bind,
+	.pr_connect = nl_pru_connect,
+	.pr_detach = nl_pru_detach,
+	.pr_disconnect = nl_pru_disconnect,
+	.pr_peeraddr = nl_pru_peeraddr,
+	.pr_send = nl_pru_send,
+	.pr_rcvd = nl_pru_rcvd,
+	.pr_shutdown = nl_pru_shutdown,
+	.pr_sockaddr = nl_pru_sockaddr,
+	.pr_close = nl_pru_close
+};
+
+static struct domain netlinkdomain = {
+	.dom_family = PF_NETLINK,
+	.dom_name = "netlink",
+	.dom_flags = DOMF_UNLOADABLE,
+	.dom_nprotosw =		1,
+	.dom_protosw =		{ &netlinksw },
+};
+
+DOMAIN_SET(netlink);