diff --git a/sbin/ifconfig/ifconfig.h b/sbin/ifconfig/ifconfig.h
--- a/sbin/ifconfig/ifconfig.h
+++ b/sbin/ifconfig/ifconfig.h
@@ -282,7 +282,6 @@
 bool	match_if_flags(struct ifconfig_args *args, int if_flags);
 int	ifconfig(if_ctx *ctx, int iscreate, const struct afswtch *uafp);
 bool	group_member(const char *ifname, const char *match, const char *nomatch);
-void	print_ifcap(struct ifconfig_args *args, int s);
 void	tunnel_status(int s);
 struct afswtch	*af_getbyfamily(int af);
 void	af_other_status(if_ctx *ctx);
diff --git a/sbin/ifconfig/ifconfig.c b/sbin/ifconfig/ifconfig.c
--- a/sbin/ifconfig/ifconfig.c
+++ b/sbin/ifconfig/ifconfig.c
@@ -55,6 +55,7 @@
 #include <net/ethernet.h>
 #include <net/if.h>
 #include <net/if_dl.h>
+#include <net/if_strings.h>
 #include <net/if_types.h>
 #include <net/route.h>
 
@@ -1633,7 +1634,7 @@
 		Perror("ioctl (SIOCGIFCAP)");
 }
 
-void
+static void
 print_ifcap(struct ifconfig_args *args, int s)
 {
 	if (ioctl(s, SIOCGIFCAP, (caddr_t)&ifr) != 0)
diff --git a/sbin/ifconfig/ifconfig_netlink.c b/sbin/ifconfig/ifconfig_netlink.c
--- a/sbin/ifconfig/ifconfig_netlink.c
+++ b/sbin/ifconfig/ifconfig_netlink.c
@@ -48,6 +48,7 @@
 #include <net/ethernet.h>
 #include <net/if.h>
 #include <net/if_dl.h>
+#include <net/if_strings.h>
 #include <net/if_types.h>
 #include "ifconfig.h"
 #include "ifconfig_netlink.h"
@@ -346,6 +347,28 @@
 	}
 }
 
+static void
+print_ifcaps(if_ctx *ctx, if_link_t *link)
+{
+	uint32_t sz_u32 = roundup2(link->iflaf_caps.nla_bitset_size, 32) / 32;
+
+	if (sz_u32 > 0) {
+		uint32_t *caps = link->iflaf_caps.nla_bitset_value;
+
+		printf("\toptions=%x", caps[0]);
+		print_bits("IFCAPS", caps, sz_u32, ifcap_bit_names, nitems(ifcap_bit_names));
+		putchar('\n');
+	}
+
+	if (ctx->args->supmedia && sz_u32 > 0) {
+		uint32_t *caps = link->iflaf_caps.nla_bitset_mask;
+
+		printf("\tcapabilities=%x", caps[0]);
+		print_bits("IFCAPS", caps, sz_u32, ifcap_bit_names, nitems(ifcap_bit_names));
+		putchar('\n');
+	}
+}
+
 static void
 status_nl(if_ctx *ctx, struct iface *iface)
 {
@@ -363,9 +386,7 @@
 	if (link->ifla_ifalias != NULL)
 		printf("\tdescription: %s\n", link->ifla_ifalias);
 
-	/* TODO: convert to netlink */
-	strlcpy(ifr.ifr_name, link->ifla_ifname, sizeof(ifr.ifr_name));
-	print_ifcap(args, ctx->io_s);
+	print_ifcaps(ctx, link);
 	tunnel_status(ctx->io_s);
 
 	if (args->allfamilies | (args->afp != NULL && args->afp->af_af == AF_LINK)) {
diff --git a/sys/net/if.h b/sys/net/if.h
--- a/sys/net/if.h
+++ b/sys/net/if.h
@@ -221,42 +221,86 @@
  * to do the right thing. However, having the filter here
  * avoids replication of the same code in all individual drivers.
  */
-#define	IFCAP_RXCSUM		0x00001  /* can offload checksum on RX */
-#define	IFCAP_TXCSUM		0x00002  /* can offload checksum on TX */
-#define	IFCAP_NETCONS		0x00004  /* can be a network console */
-#define	IFCAP_VLAN_MTU		0x00008	/* VLAN-compatible MTU */
-#define	IFCAP_VLAN_HWTAGGING	0x00010	/* hardware VLAN tag support */
-#define	IFCAP_JUMBO_MTU		0x00020	/* 9000 byte MTU supported */
-#define	IFCAP_POLLING		0x00040	/* driver supports polling */
-#define	IFCAP_VLAN_HWCSUM	0x00080	/* can do IFCAP_HWCSUM on VLANs */
-#define	IFCAP_TSO4		0x00100	/* can do TCP Segmentation Offload */
-#define	IFCAP_TSO6		0x00200	/* can do TCP6 Segmentation Offload */
-#define	IFCAP_LRO		0x00400	/* can do Large Receive Offload */
-#define	IFCAP_WOL_UCAST		0x00800	/* wake on any unicast frame */
-#define	IFCAP_WOL_MCAST		0x01000	/* wake on any multicast frame */
-#define	IFCAP_WOL_MAGIC		0x02000	/* wake on any Magic Packet */
-#define	IFCAP_TOE4		0x04000	/* interface can offload TCP */
-#define	IFCAP_TOE6		0x08000	/* interface can offload TCP6 */
-#define	IFCAP_VLAN_HWFILTER	0x10000 /* interface hw can filter vlan tag */
-#define	IFCAP_NV		0x20000 /* can do SIOCGIFCAPNV/SIOCSIFCAPNV */
-#define	IFCAP_VLAN_HWTSO	0x40000 /* can do IFCAP_TSO on VLANs */
-#define	IFCAP_LINKSTATE		0x80000 /* the runtime link state is dynamic */
-#define	IFCAP_NETMAP		0x100000 /* netmap mode supported/enabled */
-#define	IFCAP_RXCSUM_IPV6	0x200000  /* can offload checksum on IPv6 RX */
-#define	IFCAP_TXCSUM_IPV6	0x400000  /* can offload checksum on IPv6 TX */
-#define	IFCAP_HWSTATS		0x800000 /* manages counters internally */
-#define	IFCAP_TXRTLMT		0x1000000 /* hardware supports TX rate limiting */
-#define	IFCAP_HWRXTSTMP		0x2000000 /* hardware rx timestamping */
-#define	IFCAP_MEXTPG		0x4000000 /* understands M_EXTPG mbufs */
-#define	IFCAP_TXTLS4		0x8000000 /* can do TLS encryption and segmentation for TCP */
-#define	IFCAP_TXTLS6		0x10000000 /* can do TLS encryption and segmentation for TCP6 */
-#define	IFCAP_VXLAN_HWCSUM	0x20000000 /* can do IFCAN_HWCSUM on VXLANs */
-#define	IFCAP_VXLAN_HWTSO	0x40000000 /* can do IFCAP_TSO on VXLANs */
-#define	IFCAP_TXTLS_RTLMT	0x80000000 /* can do TLS with rate limiting */
+
+/* IFCAP values as bit indexes */
+
+#define	IFCAP_B_RXCSUM		0 /* can offload checksum on RX */
+#define	IFCAP_B_TXCSUM		1 /* can offload checksum on TX */
+#define	IFCAP_B_NETCONS		2 /* can be a network console */
+#define	IFCAP_B_VLAN_MTU	3 /* VLAN-compatible MTU */
+#define	IFCAP_B_VLAN_HWTAGGING	4 /* hardware VLAN tag support */
+#define	IFCAP_B_JUMBO_MTU	5 /* 9000 byte MTU supported */
+#define	IFCAP_B_POLLING		6 /* driver supports polling */
+#define	IFCAP_B_VLAN_HWCSUM	7 /* can do IFCAP_HWCSUM on VLANs */
+#define	IFCAP_B_TSO4		8 /* can do TCP Segmentation Offload */
+#define	IFCAP_B_TSO6		9 /* can do TCP6 Segmentation Offload */
+#define	IFCAP_B_LRO		10 /* can do Large Receive Offload */
+#define	IFCAP_B_WOL_UCAST	11 /* wake on any unicast frame */
+#define	IFCAP_B_WOL_MCAST	12 /* wake on any multicast frame */
+#define	IFCAP_B_WOL_MAGIC	13 /* wake on any Magic Packet */
+#define	IFCAP_B_TOE4		14 /* interface can offload TCP */
+#define	IFCAP_B_TOE6		15 /* interface can offload TCP6 */
+#define	IFCAP_B_VLAN_HWFILTER	16 /* interface hw can filter vlan tag */
+#define	IFCAP_B_NV		17 /* can do SIOCGIFCAPNV/SIOCSIFCAPNV */
+#define	IFCAP_B_VLAN_HWTSO	18 /* can do IFCAP_TSO on VLANs */
+#define	IFCAP_B_LINKSTATE	19 /* the runtime link state is dynamic */
+#define	IFCAP_B_NETMAP		20 /* netmap mode supported/enabled */
+#define	IFCAP_B_RXCSUM_IPV6	21 /* can offload checksum on IPv6 RX */
+#define	IFCAP_B_TXCSUM_IPV6	22 /* can offload checksum on IPv6 TX */
+#define	IFCAP_B_HWSTATS		23 /* manages counters internally */
+#define	IFCAP_B_TXRTLMT		24 /* hardware supports TX rate limiting */
+#define	IFCAP_B_HWRXTSTMP	25 /* hardware rx timestamping */
+#define	IFCAP_B_MEXTPG		26 /* understands M_EXTPG mbufs */
+#define	IFCAP_B_TXTLS4		27 /* can do TLS encryption and segmentation for TCP */
+#define	IFCAP_B_TXTLS6		28 /* can do TLS encryption and segmentation for TCP6 */
+#define	IFCAP_B_VXLAN_HWCSUM	29 /* can do IFCAN_HWCSUM on VXLANs */
+#define	IFCAP_B_VXLAN_HWTSO	30 /* can do IFCAP_TSO on VXLANs */
+#define	IFCAP_B_TXTLS_RTLMT	31 /* can do TLS with rate limiting */
+#define	IFCAP_B_RXTLS4		32 /* can to TLS receive for TCP */
+#define	IFCAP_B_RXTLS6		33 /* can to TLS receive for TCP6 */
+#define	__IFCAP_B_SIZE		34
+
+#define	IFCAP_B_MAX	(__IFCAP_B_MAX - 1)
+#define	IFCAP_B_SIZE	(__IFCAP_B_SIZE)
+
+#define	IFCAP_BIT(x)		(1 << (x))
+
+#define	IFCAP_RXCSUM		IFCAP_BIT(IFCAP_B_RXCSUM)
+#define	IFCAP_TXCSUM		IFCAP_BIT(IFCAP_B_TXCSUM)
+#define	IFCAP_NETCONS		IFCAP_BIT(IFCAP_B_NETCONS)
+#define	IFCAP_VLAN_MTU		IFCAP_BIT(IFCAP_B_VLAN_MTU)
+#define	IFCAP_VLAN_HWTAGGING	IFCAP_BIT(IFCAP_B_VLAN_HWTAGGING)
+#define	IFCAP_JUMBO_MTU		IFCAP_BIT(IFCAP_B_JUMBO_MTU)
+#define	IFCAP_POLLING		IFCAP_BIT(IFCAP_B_POLLING)
+#define	IFCAP_VLAN_HWCSUM	IFCAP_BIT(IFCAP_B_VLAN_HWCSUM)
+#define	IFCAP_TSO4		IFCAP_BIT(IFCAP_B_TSO4)
+#define	IFCAP_TSO6		IFCAP_BIT(IFCAP_B_TSO6)
+#define	IFCAP_LRO		IFCAP_BIT(IFCAP_B_LRO)
+#define	IFCAP_WOL_UCAST		IFCAP_BIT(IFCAP_B_WOL_UCAST)
+#define	IFCAP_WOL_MCAST		IFCAP_BIT(IFCAP_B_WOL_MCAST)
+#define	IFCAP_WOL_MAGIC		IFCAP_BIT(IFCAP_B_WOL_MAGIC)
+#define	IFCAP_TOE4		IFCAP_BIT(IFCAP_B_TOE4)
+#define	IFCAP_TOE6		IFCAP_BIT(IFCAP_B_TOE6)
+#define	IFCAP_VLAN_HWFILTER	IFCAP_BIT(IFCAP_B_VLAN_HWFILTER)
+#define	IFCAP_NV		IFCAP_BIT(IFCAP_B_NV)
+#define	IFCAP_VLAN_HWTSO	IFCAP_BIT(IFCAP_B_VLAN_HWTSO)
+#define	IFCAP_LINKSTATE		IFCAP_BIT(IFCAP_B_LINKSTATE)
+#define	IFCAP_NETMAP		IFCAP_BIT(IFCAP_B_NETMAP)
+#define	IFCAP_RXCSUM_IPV6	IFCAP_BIT(IFCAP_B_RXCSUM_IPV6)
+#define	IFCAP_TXCSUM_IPV6	IFCAP_BIT(IFCAP_B_TXCSUM_IPV6)
+#define	IFCAP_HWSTATS		IFCAP_BIT(IFCAP_B_HWSTATS)
+#define	IFCAP_TXRTLMT		IFCAP_BIT(IFCAP_B_TXRTLMT)
+#define	IFCAP_HWRXTSTMP		IFCAP_BIT(IFCAP_B_HWRXTSTMP)
+#define	IFCAP_MEXTPG		IFCAP_BIT(IFCAP_B_MEXTPG)
+#define	IFCAP_TXTLS4		IFCAP_BIT(IFCAP_B_TXTLS4)
+#define	IFCAP_TXTLS6		IFCAP_BIT(IFCAP_B_TXTLS6)
+#define	IFCAP_VXLAN_HWCSUM	IFCAP_BIT(IFCAP_B_VXLAN_HWCSUM)
+#define	IFCAP_VXLAN_HWTSO	IFCAP_BIT(IFCAP_B_VXLAN_HWTSO)
+#define	IFCAP_TXTLS_RTLMT	IFCAP_BIT(IFCAP_B_TXTLS_RTLMT)
 
 /* IFCAP2_* are integers, not bits. */
-#define	IFCAP2_RXTLS4		0
-#define	IFCAP2_RXTLS6		1
+#define	IFCAP2_RXTLS4		(IFCAP_B_RXTLS4 - 32)
+#define	IFCAP2_RXTLS6		(IFCAP_B_RXTLS6 - 32)
 
 #define	IFCAP2_BIT(x)		(1UL << (x))
 
@@ -271,40 +315,6 @@
 #define	IFCAP_CANTCHANGE	(IFCAP_NETMAP | IFCAP_NV)
 #define	IFCAP_ALLCAPS		0xffffffff
 
-#define	IFCAP_RXCSUM_NAME	"RXCSUM"
-#define	IFCAP_TXCSUM_NAME	"TXCSUM"
-#define	IFCAP_NETCONS_NAME	"NETCONS"
-#define	IFCAP_VLAN_MTU_NAME	"VLAN_MTU"
-#define	IFCAP_VLAN_HWTAGGING_NAME "VLAN_HWTAGGING"
-#define	IFCAP_JUMBO_MTU_NAME	"JUMBO_MTU"
-#define	IFCAP_POLLING_NAME	"POLLING"
-#define	IFCAP_VLAN_HWCSUM_NAME	"VLAN_HWCSUM"
-#define	IFCAP_TSO4_NAME		"TSO4"
-#define	IFCAP_TSO6_NAME		"TSO6"
-#define	IFCAP_LRO_NAME		"LRO"
-#define	IFCAP_WOL_UCAST_NAME	"WOL_UCAST"
-#define	IFCAP_WOL_MCAST_NAME	"WOL_MCAST"
-#define	IFCAP_WOL_MAGIC_NAME	"WOL_MAGIC"
-#define	IFCAP_TOE4_NAME		"TOE4"
-#define	IFCAP_TOE6_NAME		"TOE6"
-#define	IFCAP_VLAN_HWFILTER_NAME "VLAN_HWFILTER"
-#define	IFCAP_VLAN_HWTSO_NAME	"VLAN_HWTSO"
-#define	IFCAP_LINKSTATE_NAME	"LINKSTATE"
-#define	IFCAP_NETMAP_NAME	"NETMAP"
-#define	IFCAP_RXCSUM_IPV6_NAME	"RXCSUM_IPV6"
-#define	IFCAP_TXCSUM_IPV6_NAME	"TXCSUM_IPV6"
-#define	IFCAP_HWSTATS_NAME	"HWSTATS"
-#define	IFCAP_TXRTLMT_NAME	"TXRTLMT"
-#define	IFCAP_HWRXTSTMP_NAME	"HWRXTSTMP"
-#define	IFCAP_MEXTPG_NAME	"MEXTPG"
-#define	IFCAP_TXTLS4_NAME	"TXTLS4"
-#define	IFCAP_TXTLS6_NAME	"TXTLS6"
-#define	IFCAP_VXLAN_HWCSUM_NAME	"VXLAN_HWCSUM"
-#define	IFCAP_VXLAN_HWTSO_NAME	"VXLAN_HWTSO"
-#define	IFCAP_TXTLS_RTLMT_NAME	"TXTLS_RTLMT"
-#define	IFCAP2_RXTLS4_NAME	"RXTLS4"
-#define	IFCAP2_RXTLS6_NAME	"RXTLS6"
-
 #define	IFQ_MAXLEN	50
 #define	IFNET_SLOWHZ	1		/* granularity is 1 second */
 
diff --git a/sys/net/if.c b/sys/net/if.c
--- a/sys/net/if.c
+++ b/sys/net/if.c
@@ -82,6 +82,7 @@
 #include <net/if_arp.h>
 #include <net/if_clone.h>
 #include <net/if_dl.h>
+#include <net/if_strings.h>
 #include <net/if_types.h>
 #include <net/if_var.h>
 #include <net/if_media.h>
diff --git a/sys/net/if_strings.h b/sys/net/if_strings.h
new file mode 100644
--- /dev/null
+++ b/sys/net/if_strings.h
@@ -0,0 +1,106 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * 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.
+ */
+
+#ifndef _NET_IF_STRINGS_H_
+#define _NET_IF_STRINGS_H_
+
+#define	IFCAP_RXCSUM_NAME		"RXCSUM"
+#define	IFCAP_TXCSUM_NAME		"TXCSUM"
+#define	IFCAP_NETCONS_NAME		"NETCONS"
+#define	IFCAP_VLAN_MTU_NAME		"VLAN_MTU"
+#define	IFCAP_VLAN_HWTAGGING_NAME 	"VLAN_HWTAGGING"
+#define	IFCAP_JUMBO_MTU_NAME		"JUMBO_MTU"
+#define	IFCAP_POLLING_NAME		"POLLING"
+#define	IFCAP_VLAN_HWCSUM_NAME		"VLAN_HWCSUM"
+#define	IFCAP_TSO4_NAME			"TSO4"
+#define	IFCAP_TSO6_NAME			"TSO6"
+#define	IFCAP_LRO_NAME			"LRO"
+#define	IFCAP_WOL_UCAST_NAME		"WOL_UCAST"
+#define	IFCAP_WOL_MCAST_NAME		"WOL_MCAST"
+#define	IFCAP_WOL_MAGIC_NAME		"WOL_MAGIC"
+#define	IFCAP_TOE4_NAME			"TOE4"
+#define	IFCAP_TOE6_NAME			"TOE6"
+#define	IFCAP_VLAN_HWFILTER_NAME 	"VLAN_HWFILTER"
+#define	IFCAP_NV_NAME			"NV"
+#define	IFCAP_VLAN_HWTSO_NAME		"VLAN_HWTSO"
+#define	IFCAP_LINKSTATE_NAME		"LINKSTATE"
+#define	IFCAP_NETMAP_NAME		"NETMAP"
+#define	IFCAP_RXCSUM_IPV6_NAME		"RXCSUM_IPV6"
+#define	IFCAP_TXCSUM_IPV6_NAME		"TXCSUM_IPV6"
+#define	IFCAP_HWSTATS_NAME		"HWSTATS"
+#define	IFCAP_TXRTLMT_NAME		"TXRTLMT"
+#define	IFCAP_HWRXTSTMP_NAME		"HWRXTSTMP"
+#define	IFCAP_MEXTPG_NAME		"MEXTPG"
+#define	IFCAP_TXTLS4_NAME		"TXTLS4"
+#define	IFCAP_TXTLS6_NAME		"TXTLS6"
+#define	IFCAP_VXLAN_HWCSUM_NAME		"VXLAN_HWCSUM"
+#define	IFCAP_VXLAN_HWTSO_NAME		"VXLAN_HWTSO"
+#define	IFCAP_TXTLS_RTLMT_NAME		"TXTLS_RTLMT"
+#define	IFCAP_RXTLS4_NAME		"RXTLS4"
+#define	IFCAP_RXTLS6_NAME		"RXTLS6"
+
+#define	IFCAP2_RXTLS4_NAME	IFCAP_RXTLS4_NAME
+#define	IFCAP2_RXTLS6_NAME	IFCAP_RXTLS6_NAME
+
+static const char *ifcap_bit_names[] = {
+	IFCAP_RXCSUM_NAME,
+	IFCAP_TXCSUM_NAME,
+	IFCAP_NETCONS_NAME,
+	IFCAP_VLAN_MTU_NAME,
+	IFCAP_VLAN_HWTAGGING_NAME,
+	IFCAP_JUMBO_MTU_NAME,
+	IFCAP_POLLING_NAME,
+	IFCAP_VLAN_HWCSUM_NAME,
+	IFCAP_TSO4_NAME,
+	IFCAP_TSO6_NAME,
+	IFCAP_LRO_NAME,
+	IFCAP_WOL_UCAST_NAME,
+	IFCAP_WOL_MCAST_NAME,
+	IFCAP_WOL_MAGIC_NAME,
+	IFCAP_TOE4_NAME,
+	IFCAP_TOE6_NAME,
+	IFCAP_VLAN_HWFILTER_NAME,
+	IFCAP_NV_NAME,
+	IFCAP_VLAN_HWTSO_NAME,
+	IFCAP_LINKSTATE_NAME,
+	IFCAP_NETMAP_NAME,
+	IFCAP_RXCSUM_IPV6_NAME,
+	IFCAP_TXCSUM_IPV6_NAME,
+	IFCAP_HWSTATS_NAME,
+	IFCAP_TXRTLMT_NAME,
+	IFCAP_HWRXTSTMP_NAME,
+	IFCAP_MEXTPG_NAME,
+	IFCAP_TXTLS4_NAME,
+	IFCAP_TXTLS6_NAME,
+	IFCAP_VXLAN_HWCSUM_NAME,
+	IFCAP_VXLAN_HWTSO_NAME,
+	IFCAP_TXTLS_RTLMT_NAME,
+	IFCAP_RXTLS4_NAME,
+	IFCAP_RXTLS6_NAME,
+};
+_Static_assert(sizeof(ifcap_bit_names) >= IFCAP_B_SIZE * sizeof(char *),
+    "ifcap bit names missing from ifcap_bit_names");
+
+#endif
diff --git a/sys/netlink/netlink_route.h b/sys/netlink/netlink_bitset.h
copy from sys/netlink/netlink_route.h
copy to sys/netlink/netlink_bitset.h
--- a/sys/netlink/netlink_route.h
+++ b/sys/netlink/netlink_bitset.h
@@ -1,7 +1,7 @@
 /*-
  * SPDX-License-Identifier: BSD-2-Clause
  *
- * Copyright (c) 2022 Alexander V. Chernikov <melifaro@FreeBSD.org>
+ * Copyright (c) 2023 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
@@ -24,20 +24,34 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  */
-#ifndef _NETLINK_NETLINK_ROUTE_H_
-#define	_NETLINK_NETLINK_ROUTE_H_
 
-#include <sys/types.h>
+/*
+ * Generic netlink message header and attributes
+ */
+#ifndef _NETLINK_NETLINK_BITSET_H_
+#define	_NETLINK_NETLINK_BITSET_H_
+
+#include <netlink/netlink.h>
 
-#include <net/if.h>
-#include <net/if_types.h>
-#include <net/if_var.h>
+/* Bitset type nested attributes */
+enum {
+	NLA_BITSET_UNSPEC,
+	NLA_BITSET_NOMASK	= 1, /* flag: mask of valid bits not provided */
+	NLA_BITSET_SIZE		= 2, /* u32: max valid bit # */
+	NLA_BITSET_BITS		= 3, /* nested: array of NLA_BITSET_BIT */
+	NLA_BITSET_VALUE	= 4, /* binary: array of bit values */
+	NLA_BITSET_MASK		= 5, /* binary: array of valid bits */
+	__NLA_BITSET_MAX,
+};
+#define	NLA_BITSET_MAX	(__NLA_BITSET_MAX - 1)
 
-#include <netlink/route/common.h>
-#include <netlink/route/ifaddrs.h>
-#include <netlink/route/interface.h>
-#include <netlink/route/neigh.h>
-#include <netlink/route/route.h>
-#include <netlink/route/nexthop.h>
+enum {
+	NLA_BITSET_BIT_UNSPEC,
+	NLA_BITSET_BIT_INDEX	= 1, /* u32: index of the bit */
+	NLA_BITSET_BIT_NAME	= 2, /* string: bit description */
+	NLA_BITSET_BIT_VALUE	= 3, /* flag: provided if bit is set */
+	__NLA_BITSET_BIT_MAX,
+};
+#define	NLA_BITSET_BIT_MAX	(__NLA_BITSET_BIT_MAX - 1)
 
 #endif
diff --git a/sys/netlink/netlink_route.h b/sys/netlink/netlink_route.h
--- a/sys/netlink/netlink_route.h
+++ b/sys/netlink/netlink_route.h
@@ -33,6 +33,7 @@
 #include <net/if_types.h>
 #include <net/if_var.h>
 
+#include <netlink/netlink_bitset.h>
 #include <netlink/route/common.h>
 #include <netlink/route/ifaddrs.h>
 #include <netlink/route/interface.h>
diff --git a/sys/netlink/netlink_snl.h b/sys/netlink/netlink_snl.h
--- a/sys/netlink/netlink_snl.h
+++ b/sys/netlink/netlink_snl.h
@@ -43,6 +43,7 @@
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <netlink/netlink.h>
+#include <netlink/netlink_bitset.h>
 
 #define _roundup2(x, y)         (((x)+((y)-1))&(~((y)-1)))
 
@@ -732,7 +733,7 @@
 }
 
 static inline bool
-snl_attr_dup_nla(struct snl_state *ss __unused, struct nlattr *nla,
+snl_attr_dup_nla(struct snl_state *ss, struct nlattr *nla,
     const void *arg __unused, void *target)
 {
 	void *ptr = snl_allocz(ss, nla->nla_len);
@@ -773,6 +774,89 @@
 	return (false);
 }
 
+struct snl_attr_bit {
+	uint32_t	bit_index;
+	char		*bit_name;
+	int		bit_value;
+};
+
+struct snl_attr_bits {
+	uint32_t num_bits;
+	struct snl_attr_bit **bits;
+};
+
+#define	_OUT(_field)	offsetof(struct snl_attr_bit, _field)
+static const struct snl_attr_parser _nla_p_bit[] = {
+	{ .type = NLA_BITSET_BIT_INDEX, .off = _OUT(bit_index), .cb = snl_attr_get_uint32 },
+	{ .type = NLA_BITSET_BIT_NAME, .off = _OUT(bit_name), .cb = snl_attr_dup_string },
+	{ .type = NLA_BITSET_BIT_VALUE, .off = _OUT(bit_value), .cb = snl_attr_get_flag },
+};
+#undef _OUT
+SNL_DECLARE_ATTR_PARSER_EXT(_nla_bit_parser, sizeof(struct snl_attr_bit), _nla_p_bit, NULL);
+
+struct snl_attr_bitset {
+	uint32_t		nla_bitset_size;
+	uint32_t		*nla_bitset_mask;
+	uint32_t		*nla_bitset_value;
+	struct snl_attr_bits	bits;
+};
+
+#define	_OUT(_field)	offsetof(struct snl_attr_bitset, _field)
+static const struct snl_attr_parser _nla_p_bitset[] = {
+	{ .type = NLA_BITSET_SIZE, .off = _OUT(nla_bitset_size), .cb = snl_attr_get_uint32 },
+	{ .type = NLA_BITSET_BITS, .off = _OUT(bits), .cb = snl_attr_get_parray, .arg = &_nla_bit_parser },
+	{ .type = NLA_BITSET_VALUE, .off = _OUT(nla_bitset_mask), .cb = snl_attr_dup_nla },
+	{ .type = NLA_BITSET_MASK, .off = _OUT(nla_bitset_value), .cb = snl_attr_dup_nla },
+};
+
+static inline bool
+_cb_p_bitset(struct snl_state *ss __unused, void *_target)
+{
+	struct snl_attr_bitset *target = _target;
+
+	uint32_t sz_bytes = _roundup2(target->nla_bitset_size, 32) / 8;
+
+	if (target->nla_bitset_mask != NULL) {
+		struct nlattr *nla = (struct nlattr *)target->nla_bitset_mask;
+		uint32_t data_len = NLA_DATA_LEN(nla);
+
+		if (data_len != sz_bytes || _roundup2(data_len, 4) != data_len)
+			return (false);
+		target->nla_bitset_mask = (uint32_t *)NLA_DATA(nla);
+	}
+
+	if (target->nla_bitset_value != NULL) {
+		struct nlattr *nla = (struct nlattr *)target->nla_bitset_value;
+		uint32_t data_len = NLA_DATA_LEN(nla);
+
+		if (data_len != sz_bytes || _roundup2(data_len, 4) != data_len)
+			return (false);
+		target->nla_bitset_value = (uint32_t *)NLA_DATA(nla);
+	}
+	return (true);
+}
+#undef _OUT
+SNL_DECLARE_ATTR_PARSER_EXT(_nla_bitset_parser,
+		sizeof(struct snl_attr_bitset),
+		_nla_p_bitset, _cb_p_bitset);
+
+/*
+ * Parses the compact bitset representation.
+ */
+static inline bool
+snl_attr_get_bitset_c(struct snl_state *ss, struct nlattr *nla, const void *arg, void *_target)
+{
+	const struct snl_hdr_parser *p = &_nla_bitset_parser;
+	struct snl_attr_bitset *target = _target;
+
+	/* Assumes target points to the beginning of the structure */
+	if (!snl_parse_header(ss, NLA_DATA(nla), NLA_DATA_LEN(nla), p, _target))
+		return (false);
+	if (target->nla_bitset_mask == NULL || target->nla_bitset_value == NULL)
+		return (false);
+	return (true);
+}
+
 static inline void
 snl_field_get_uint8(struct snl_state *ss __unused, void *src, void *target)
 {
@@ -1184,6 +1268,7 @@
 
 static const struct snl_hdr_parser *snl_all_core_parsers[] = {
 	&snl_errmsg_parser, &snl_donemsg_parser,
+	&_nla_bit_parser, &_nla_bitset_parser,
 };
 
 #endif
diff --git a/sys/netlink/netlink_snl_route_parsers.h b/sys/netlink/netlink_snl_route_parsers.h
--- a/sys/netlink/netlink_snl_route_parsers.h
+++ b/sys/netlink/netlink_snl_route_parsers.h
@@ -186,12 +186,14 @@
 	uint32_t			ifla_promiscuity;
 	struct rtnl_link_stats64	*ifla_stats64;
 	struct nlattr			*iflaf_orig_hwaddr;
+	struct snl_attr_bitset		iflaf_caps;
 };
 
 #define	_IN(_field)	offsetof(struct ifinfomsg, _field)
 #define	_OUT(_field)	offsetof(struct snl_parsed_link, _field)
 static const struct snl_attr_parser _nla_p_link_fbsd[] = {
 	{ .type = IFLAF_ORIG_HWADDR, .off = _OUT(iflaf_orig_hwaddr), .cb = snl_attr_dup_nla },
+	{ .type = IFLAF_CAPS, .off = _OUT(iflaf_caps), .cb = snl_attr_get_bitset_c },
 };
 SNL_DECLARE_ATTR_PARSER(_link_fbsd_parser, _nla_p_link_fbsd);
 
diff --git a/sys/netlink/route/iface.c b/sys/netlink/route/iface.c
--- a/sys/netlink/route/iface.c
+++ b/sys/netlink/route/iface.c
@@ -253,6 +253,33 @@
         return (nlattr_add(nw, attr, addr_len, addr_data));
 }
 
+static bool
+dump_iface_caps(struct nl_writer *nw, struct ifnet *ifp)
+{
+	int off = nlattr_add_nested(nw, IFLAF_CAPS);
+	uint32_t active_caps[roundup2(IFCAP_B_SIZE, 32) / 32] = {};
+	uint32_t all_caps[roundup2(IFCAP_B_SIZE, 32) / 32] = {};
+
+	MPASS(sizeof(active_caps) >= 8);
+	MPASS(sizeof(all_caps) >= 8);
+
+	if (off == 0)
+		return (false);
+
+	active_caps[0] = (uint32_t)if_getcapabilities(ifp);
+	all_caps[0] = (uint32_t)if_getcapenable(ifp);
+	active_caps[1] = (uint32_t)if_getcapabilities2(ifp);
+	all_caps[1] = (uint32_t)if_getcapenable2(ifp);
+
+	nlattr_add_u32(nw, NLA_BITSET_SIZE, IFCAP_B_SIZE);
+	nlattr_add(nw, NLA_BITSET_MASK, sizeof(all_caps), all_caps);
+	nlattr_add(nw, NLA_BITSET_VALUE, sizeof(active_caps), active_caps);
+
+	nlattr_set_len(nw, off);
+
+	return (true);
+}
+
 /*
  * Dumps interface state, properties and metrics.
  * @nw: message writer
@@ -320,6 +347,7 @@
 	int off = nlattr_add_nested(nw, IFLA_FREEBSD);
 	if (off != 0) {
 		get_hwaddr(nw, ifp);
+		dump_iface_caps(nw, ifp);
 
 		nlattr_set_len(nw, off);
 	}
diff --git a/sys/netlink/route/interface.h b/sys/netlink/route/interface.h
--- a/sys/netlink/route/interface.h
+++ b/sys/netlink/route/interface.h
@@ -151,6 +151,7 @@
 	IFLAF_UNSPEC		= 0,
 	IFLAF_ORIG_IFNAME	= 1,	/* string, original interface name at creation */
 	IFLAF_ORIG_HWADDR	= 2,	/* binary, original hardware address */
+	IFLAF_CAPS		= 3,	/* bitset, interface capabilities */
 	__IFLAF_MAX
 };
 #define IFLAF_MAX (__IFLAF_MAX - 1)