netlink: allow creating sockets with SOCK_DGRAM.

Some existing applications setup Netlink socket with
SOCK_DGRAM instead of SOCK_RAW. Update the manpage to clarify
that the default way of creating the socket should be with
SOCK_RAW. Update the code to support both SOCK_RAW and SOCK_DGRAM.

Reviewed By: pauamma
Differential Revision: https://reviews.freebsd.org/D38075

(cherry picked from commit 0079d177ab69168df5e103128a2b15bd8e74d4eb)

4 files changed, 49 insertions, 6 deletions

diff --git a/share/man/man4/netlink.4 b/share/man/man4/netlink.4
index 2aa4903a4594..1894de5841fe 100644
--- a/share/man/man4/netlink.4
+++ b/share/man/man4/netlink.4
@@ -34,7 +34,7 @@
 .In netlink/netlink.h
 .In netlink/netlink_route.h
 .Ft int
-.Fn socket AF_NETLINK SOCK_DGRAM int family
+.Fn socket AF_NETLINK SOCK_RAW "int family"
 .Sh DESCRIPTION
 Netlink is a user-kernel message-based communication protocol primarily used
 for network stack configuration.
@@ -293,7 +293,7 @@ This is the default level, not impacting production performance.
 Socket events such as groups memberships, privilege checks, commands and dumps
 are logged.
 This level does not incur significant performance overhead.
-.It Dv LOG_DEBUG9(9)
+.It Dv LOG_DEBUG3(9)
 All socket events, each dumped or modified entities are logged.
 Turning it on may result in significant performance overhead.
 .El
diff --git a/share/man/man4/rtnetlink.4 b/share/man/man4/rtnetlink.4
index dc40b277d934..5849508b74c2 100644
--- a/share/man/man4/rtnetlink.4
+++ b/share/man/man4/rtnetlink.4
@@ -34,7 +34,7 @@
 .In netlink/netlink.h
 .In netlink/netlink_route.h
 .Ft int
-.Fn socket AF_NETLINK SOCK_DGRAM NETLINK_ROUTE
+.Fn socket AF_NETLINK SOCK_RAW NETLINK_ROUTE
 .Sh DESCRIPTION
 The
 .Dv NETLINK_ROUTE
diff --git a/sys/netlink/netlink_domain.c b/sys/netlink/netlink_domain.c
index 3b5e897164f8..de96818d5e35 100644
--- a/sys/netlink/netlink_domain.c
+++ b/sys/netlink/netlink_domain.c
@@ -721,13 +721,23 @@ struct pr_usrreqs nl_usrreqs = {
 
 static struct domain netlinkdomain;
 
-static struct protosw netlinksw = {
+static struct protosw netlinksw[] = {
+{
 	.pr_type = SOCK_RAW,
 	.pr_domain = &netlinkdomain,
 	.pr_protocol = 0, // IPPROTO_UDP
 	.pr_flags = PR_ATOMIC | PR_ADDR | PR_WANTRCVD,
 	.pr_ctloutput = nl_ctloutput,
 	.pr_usrreqs = &nl_usrreqs,
+},
+{
+	.pr_type = SOCK_DGRAM,
+	.pr_domain = &netlinkdomain,
+	.pr_protocol = 0, // IPPROTO_UDP
+	.pr_flags = PR_ATOMIC | PR_ADDR | PR_WANTRCVD,
+	.pr_ctloutput = nl_ctloutput,
+	.pr_usrreqs = &nl_usrreqs,
+}
 };
 
 static struct domain netlinkdomain = {
@@ -736,8 +746,8 @@ static struct domain netlinkdomain = {
 #ifdef	DOMF_UNLOADABLE
 	.dom_flags = DOMF_UNLOADABLE,
 #endif
-	.dom_protosw =		&netlinksw,
-	.dom_protoswNPROTOSW =	(&netlinksw + 1),
+	.dom_protosw =		&netlinksw[0],
+	.dom_protoswNPROTOSW =	(&netlinksw[0] + 2),
 };
 
 DOMAIN_SET(netlink);
diff --git a/tests/sys/netlink/test_nl_core.py b/tests/sys/netlink/test_nl_core.py
new file mode 100644
index 000000000000..7af421a929dc
--- /dev/null
+++ b/tests/sys/netlink/test_nl_core.py
@@ -0,0 +1,33 @@
+import errno
+import socket
+
+import pytest
+from atf_python.sys.net.netlink import NetlinkTestTemplate
+from atf_python.sys.net.netlink import NlConst
+from atf_python.sys.net.vnet import SingleVnetTestTemplate
+
+
+class TestNlCore(NetlinkTestTemplate, SingleVnetTestTemplate):
+    @pytest.mark.parametrize(
+        "params",
+        [
+            pytest.param({"type": socket.SOCK_RAW}, id="SOCK_RAW"),
+            pytest.param({"type": socket.SOCK_DGRAM}, id="SOCK_DGRAM"),
+        ],
+    )
+    def test_socket_type(self, params):
+        s = socket.socket(NlConst.AF_NETLINK, params["type"], NlConst.NETLINK_ROUTE)
+        s.close()
+
+    @pytest.mark.parametrize(
+        "params",
+        [
+            pytest.param({"type": socket.SOCK_STREAM}, id="SOCK_STREAM"),
+            pytest.param({"type": socket.SOCK_RDM}, id="SOCK_RDM"),
+            pytest.param({"type": socket.SOCK_SEQPACKET}, id="SOCK_SEQPACKET"),
+        ],
+    )
+    def test_socket_type_unsup(self, params):
+        with pytest.raises(OSError) as exc_info:
+            socket.socket(NlConst.AF_NETLINK, params["type"], NlConst.NETLINK_ROUTE)
+        assert exc_info.value.errno == errno.EPROTOTYPE