Adding upstream version 1.14.0.upstream/1.14.0

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 785 insertions, 0 deletions

diff --git a/src/netlink.c b/src/netlink.c
new file mode 100644
index 0000000..2a9216c
--- /dev/null
+++ b/src/netlink.c
@@ -0,0 +1,785 @@
+/*
+ * Copyright (c) 2020 Yubico AB. All rights reserved.
+ * Use of this source code is governed by a BSD-style
+ * license that can be found in the LICENSE file.
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <sys/socket.h>
+
+#include <linux/genetlink.h>
+#include <linux/netlink.h>
+#include <linux/nfc.h>
+
+#include <errno.h>
+#include <limits.h>
+
+#include "fido.h"
+#include "netlink.h"
+
+#ifdef FIDO_FUZZ
+static ssize_t (*fuzz_read)(int, void *, size_t);
+static ssize_t (*fuzz_write)(int, const void *, size_t);
+# define READ	fuzz_read
+# define WRITE	fuzz_write
+#else
+# define READ	read
+# define WRITE	write
+#endif
+
+#ifndef SOL_NETLINK
+#define SOL_NETLINK	270
+#endif
+
+#define NETLINK_POLL_MS	100
+
+/* XXX avoid signed NLA_ALIGNTO */
+#undef NLA_HDRLEN
+#define NLA_HDRLEN	NLMSG_ALIGN(sizeof(struct nlattr))
+
+typedef struct nlmsgbuf {
+	size_t         siz; /* alloc size */
+	size_t         len; /* of payload */
+	unsigned char *ptr; /* in payload */
+	union {
+		struct nlmsghdr   nlmsg;
+		char              buf[NLMSG_HDRLEN]; /* align */
+	}              u;
+	unsigned char  payload[];
+} nlmsgbuf_t;
+
+typedef struct genlmsgbuf {
+	union {
+		struct genlmsghdr genl;
+		char              buf[GENL_HDRLEN];  /* align */
+	}              u;
+} genlmsgbuf_t;
+
+typedef struct nlamsgbuf {
+	size_t         siz; /* alloc size */
+	size_t         len; /* of payload */
+	unsigned char *ptr; /* in payload */
+	union {
+		struct nlattr     nla;
+		char              buf[NLA_HDRLEN];   /* align */
+	}              u;
+	unsigned char  payload[];
+} nlamsgbuf_t;
+
+typedef struct nl_family {
+	uint16_t id;
+	uint32_t mcastgrp;
+} nl_family_t;
+
+typedef struct nl_poll {
+	uint32_t     dev;
+	unsigned int eventcnt;
+} nl_poll_t;
+
+typedef struct nl_target {
+	int       found;
+	uint32_t *value;
+} nl_target_t;
+
+static const void *
+nlmsg_ptr(const nlmsgbuf_t *m)
+{
+	return (&m->u.nlmsg);
+}
+
+static size_t
+nlmsg_len(const nlmsgbuf_t *m)
+{
+	return (m->u.nlmsg.nlmsg_len);
+}
+
+static uint16_t
+nlmsg_type(const nlmsgbuf_t *m)
+{
+	return (m->u.nlmsg.nlmsg_type);
+}
+
+static nlmsgbuf_t *
+nlmsg_new(uint16_t type, uint16_t flags, size_t len)
+{
+	nlmsgbuf_t *m;
+	size_t siz;
+
+	if (len > SIZE_MAX - sizeof(*m) ||
+	    (siz = sizeof(*m) + len) > UINT16_MAX ||
+	    (m = calloc(1, siz)) == NULL)
+		return (NULL);
+
+	m->siz = siz;
+	m->len = len;
+	m->ptr = m->payload;
+	m->u.nlmsg.nlmsg_type = type;
+	m->u.nlmsg.nlmsg_flags = NLM_F_REQUEST | flags;
+	m->u.nlmsg.nlmsg_len = NLMSG_HDRLEN;
+
+	return (m);
+}
+
+static nlamsgbuf_t *
+nla_from_buf(const unsigned char **ptr, size_t *len)
+{
+	nlamsgbuf_t h, *a;
+	size_t nlalen, skip;
+
+	if (*len < sizeof(h.u))
+		return (NULL);
+
+	memset(&h, 0, sizeof(h));
+	memcpy(&h.u, *ptr, sizeof(h.u));
+
+	if ((nlalen = h.u.nla.nla_len) < sizeof(h.u) || nlalen > *len ||
+	    nlalen - sizeof(h.u) > UINT16_MAX ||
+	    nlalen > SIZE_MAX - sizeof(*a) ||
+	    (skip = NLMSG_ALIGN(nlalen)) > *len ||
+	    (a = calloc(1, sizeof(*a) + nlalen - sizeof(h.u))) == NULL)
+		return (NULL);
+
+	memcpy(&a->u, *ptr, nlalen);
+	a->siz = sizeof(*a) + nlalen - sizeof(h.u);
+	a->ptr = a->payload;
+	a->len = nlalen - sizeof(h.u);
+	*ptr += skip;
+	*len -= skip;
+
+	return (a);
+}
+
+static nlamsgbuf_t *
+nla_getattr(nlamsgbuf_t *a)
+{
+	return (nla_from_buf((void *)&a->ptr, &a->len));
+}
+
+static uint16_t
+nla_type(const nlamsgbuf_t *a)
+{
+	return (a->u.nla.nla_type);
+}
+
+static nlamsgbuf_t *
+nlmsg_getattr(nlmsgbuf_t *m)
+{
+	return (nla_from_buf((void *)&m->ptr, &m->len));
+}
+
+static int
+nla_read(nlamsgbuf_t *a, void *buf, size_t cnt)
+{
+	if (cnt > a->u.nla.nla_len ||
+	    fido_buf_read((void *)&a->ptr, &a->len, buf, cnt) < 0)
+		return (-1);
+
+	a->u.nla.nla_len = (uint16_t)(a->u.nla.nla_len - cnt);
+
+	return (0);
+}
+
+static nlmsgbuf_t *
+nlmsg_from_buf(const unsigned char **ptr, size_t *len)
+{
+	nlmsgbuf_t h, *m;
+	size_t msglen, skip;
+
+	if (*len < sizeof(h.u))
+		return (NULL);
+
+	memset(&h, 0, sizeof(h));
+	memcpy(&h.u, *ptr, sizeof(h.u));
+
+	if ((msglen = h.u.nlmsg.nlmsg_len) < sizeof(h.u) || msglen > *len ||
+	    msglen - sizeof(h.u) > UINT16_MAX ||
+	    (skip = NLMSG_ALIGN(msglen)) > *len ||
+	    (m = nlmsg_new(0, 0, msglen - sizeof(h.u))) == NULL)
+		return (NULL);
+
+	memcpy(&m->u, *ptr, msglen);
+	*ptr += skip;
+	*len -= skip;
+
+	return (m);
+}
+
+static int
+nlmsg_read(nlmsgbuf_t *m, void *buf, size_t cnt)
+{
+	if (cnt > m->u.nlmsg.nlmsg_len ||
+	    fido_buf_read((void *)&m->ptr, &m->len, buf, cnt) < 0)
+		return (-1);
+
+	m->u.nlmsg.nlmsg_len = (uint32_t)(m->u.nlmsg.nlmsg_len - cnt);
+
+	return (0);
+}
+
+static int
+nlmsg_write(nlmsgbuf_t *m, const void *buf, size_t cnt)
+{
+	if (cnt > UINT32_MAX - m->u.nlmsg.nlmsg_len ||
+	    fido_buf_write(&m->ptr, &m->len, buf, cnt) < 0)
+		return (-1);
+
+	m->u.nlmsg.nlmsg_len = (uint32_t)(m->u.nlmsg.nlmsg_len + cnt);
+
+	return (0);
+}
+
+static int
+nlmsg_set_genl(nlmsgbuf_t *m, uint8_t cmd)
+{
+	genlmsgbuf_t g;
+
+	memset(&g, 0, sizeof(g));
+	g.u.genl.cmd = cmd;
+	g.u.genl.version = NFC_GENL_VERSION;
+
+	return (nlmsg_write(m, &g, sizeof(g)));
+}
+
+static int
+nlmsg_get_genl(nlmsgbuf_t *m, uint8_t cmd)
+{
+	genlmsgbuf_t g;
+
+	memset(&g, 0, sizeof(g));
+
+	if (nlmsg_read(m, &g, sizeof(g)) < 0 || g.u.genl.cmd != cmd)
+		return (-1);
+
+	return (0);
+}
+
+static int
+nlmsg_get_status(nlmsgbuf_t *m)
+{
+	int status;
+
+	if (nlmsg_read(m, &status, sizeof(status)) < 0 || status == INT_MIN)
+		return (-1);
+	if (status < 0)
+		status = -status;
+
+	return (status);
+}
+
+static int
+nlmsg_setattr(nlmsgbuf_t *m, uint16_t type, const void *ptr, size_t len)
+{
+	int r;
+	char *padding;
+	size_t skip;
+	nlamsgbuf_t a;
+
+	if ((skip = NLMSG_ALIGN(len)) > UINT16_MAX - sizeof(a.u) ||
+	    skip < len || (padding = calloc(1, skip - len)) == NULL)
+		return (-1);
+
+	memset(&a, 0, sizeof(a));
+	a.u.nla.nla_type = type;
+	a.u.nla.nla_len = (uint16_t)(len + sizeof(a.u));
+	r = nlmsg_write(m, &a.u, sizeof(a.u)) < 0 ||
+	    nlmsg_write(m, ptr, len) < 0 ||
+	    nlmsg_write(m, padding, skip - len) < 0 ? -1 : 0;
+
+	free(padding);
+
+	return (r);
+}
+
+static int
+nlmsg_set_u16(nlmsgbuf_t *m, uint16_t type, uint16_t val)
+{
+	return (nlmsg_setattr(m, type, &val, sizeof(val)));
+}
+
+static int
+nlmsg_set_u32(nlmsgbuf_t *m, uint16_t type, uint32_t val)
+{
+	return (nlmsg_setattr(m, type, &val, sizeof(val)));
+}
+
+static int
+nlmsg_set_str(nlmsgbuf_t *m, uint16_t type, const char *val)
+{
+	return (nlmsg_setattr(m, type, val, strlen(val) + 1));
+}
+
+static int
+nla_get_u16(nlamsgbuf_t *a, uint16_t *v)
+{
+	return (nla_read(a, v, sizeof(*v)));
+}
+
+static int
+nla_get_u32(nlamsgbuf_t *a, uint32_t *v)
+{
+	return (nla_read(a, v, sizeof(*v)));
+}
+
+static char *
+nla_get_str(nlamsgbuf_t *a)
+{
+	size_t n;
+	char *s = NULL;
+
+	if ((n = a->len) < 1 || a->ptr[n - 1] != '\0' ||
+	    (s = calloc(1, n)) == NULL || nla_read(a, s, n) < 0) {
+		free(s);
+		return (NULL);
+	}
+	s[n - 1] = '\0';
+
+	return (s);
+}
+
+static int
+nlmsg_tx(int fd, const nlmsgbuf_t *m)
+{
+	ssize_t r;
+
+	if ((r = WRITE(fd, nlmsg_ptr(m), nlmsg_len(m))) == -1) {
+		fido_log_error(errno, "%s: write", __func__);
+		return (-1);
+	}
+	if (r < 0 || (size_t)r != nlmsg_len(m)) {
+		fido_log_debug("%s: %zd != %zu", __func__, r, nlmsg_len(m));
+		return (-1);
+	}
+	fido_log_xxd(nlmsg_ptr(m), nlmsg_len(m), "%s", __func__);
+
+	return (0);
+}
+
+static ssize_t
+nlmsg_rx(int fd, unsigned char *ptr, size_t len, int ms)
+{
+	ssize_t r;
+
+	if (len > SSIZE_MAX) {
+		fido_log_debug("%s: len", __func__);
+		return (-1);
+	}
+	if (fido_hid_unix_wait(fd, ms, NULL) < 0) {
+		fido_log_debug("%s: fido_hid_unix_wait", __func__);
+		return (-1);
+	}
+	if ((r = READ(fd, ptr, len)) == -1) {
+		fido_log_error(errno, "%s: read %zd", __func__, r);
+		return (-1);
+	}
+	fido_log_xxd(ptr, (size_t)r, "%s", __func__);
+
+	return (r);
+}
+
+static int
+nlmsg_iter(nlmsgbuf_t *m, void *arg, int (*parser)(nlamsgbuf_t *, void *))
+{
+	nlamsgbuf_t *a;
+	int r;
+
+	while ((a = nlmsg_getattr(m)) != NULL) {
+		r = parser(a, arg);
+		free(a);
+		if (r < 0) {
+			fido_log_debug("%s: parser", __func__);
+			return (-1);
+		}
+	}
+
+	return (0);
+}
+
+static int
+nla_iter(nlamsgbuf_t *g, void *arg, int (*parser)(nlamsgbuf_t *, void *))
+{
+	nlamsgbuf_t *a;
+	int r;
+
+	while ((a = nla_getattr(g)) != NULL) {
+		r = parser(a, arg);
+		free(a);
+		if (r < 0) {
+			fido_log_debug("%s: parser", __func__);
+			return (-1);
+		}
+	}
+
+	return (0);
+}
+
+static int
+nl_parse_reply(const uint8_t *blob, size_t blob_len, uint16_t msg_type,
+    uint8_t genl_cmd, void *arg, int (*parser)(nlamsgbuf_t *, void *))
+{
+	nlmsgbuf_t *m;
+	int r;
+
+	while (blob_len) {
+		if ((m = nlmsg_from_buf(&blob, &blob_len)) == NULL) {
+			fido_log_debug("%s: nlmsg", __func__);
+			return (-1);
+		}
+		if (nlmsg_type(m) == NLMSG_ERROR) {
+			r = nlmsg_get_status(m);
+			free(m);
+			return (r);
+		}
+		if (nlmsg_type(m) != msg_type ||
+		    nlmsg_get_genl(m, genl_cmd) < 0) {
+			fido_log_debug("%s: skipping", __func__);
+			free(m);
+			continue;
+		}
+		if (parser != NULL && nlmsg_iter(m, arg, parser) < 0) {
+			fido_log_debug("%s: nlmsg_iter", __func__);
+			free(m);
+			return (-1);
+		}
+		free(m);
+	}
+
+	return (0);
+}
+
+static int
+parse_mcastgrp(nlamsgbuf_t *a, void *arg)
+{
+	nl_family_t *family = arg;
+	char *name;
+
+	switch (nla_type(a)) {
+	case CTRL_ATTR_MCAST_GRP_NAME:
+		if ((name = nla_get_str(a)) == NULL ||
+		    strcmp(name, NFC_GENL_MCAST_EVENT_NAME) != 0) {
+			free(name);
+			return (-1); /* XXX skip? */
+		}
+		free(name);
+		return (0);
+	case CTRL_ATTR_MCAST_GRP_ID:
+		if (family->mcastgrp)
+			break;
+		if (nla_get_u32(a, &family->mcastgrp) < 0) {
+			fido_log_debug("%s: group", __func__);
+			return (-1);
+		}
+		return (0);
+	}
+
+	fido_log_debug("%s: ignoring nla 0x%x", __func__, nla_type(a));
+
+	return (0);
+}
+
+static int
+parse_mcastgrps(nlamsgbuf_t *a, void *arg)
+{
+	return (nla_iter(a, arg, parse_mcastgrp));
+}
+
+static int
+parse_family(nlamsgbuf_t *a, void *arg)
+{
+	nl_family_t *family = arg;
+
+	switch (nla_type(a)) {
+	case CTRL_ATTR_FAMILY_ID:
+		if (family->id)
+			break;
+		if (nla_get_u16(a, &family->id) < 0) {
+			fido_log_debug("%s: id", __func__);
+			return (-1);
+		}
+		return (0);
+	case CTRL_ATTR_MCAST_GROUPS:
+		return (nla_iter(a, family, parse_mcastgrps));
+	}
+
+	fido_log_debug("%s: ignoring nla 0x%x", __func__, nla_type(a));
+
+	return (0);
+}
+
+static int
+nl_get_nfc_family(int fd, uint16_t *type, uint32_t *mcastgrp)
+{
+	nlmsgbuf_t *m;
+	uint8_t reply[512];
+	nl_family_t family;
+	ssize_t r;
+	int ok;
+
+	if ((m = nlmsg_new(GENL_ID_CTRL, 0, 64)) == NULL ||
+	    nlmsg_set_genl(m, CTRL_CMD_GETFAMILY) < 0 ||
+	    nlmsg_set_u16(m, CTRL_ATTR_FAMILY_ID, GENL_ID_CTRL) < 0 ||
+	    nlmsg_set_str(m, CTRL_ATTR_FAMILY_NAME, NFC_GENL_NAME) < 0 ||
+	    nlmsg_tx(fd, m) < 0) {
+		free(m);
+		return (-1);
+	}
+	free(m);
+	memset(&family, 0, sizeof(family));
+	if ((r = nlmsg_rx(fd, reply, sizeof(reply), -1)) < 0) {
+		fido_log_debug("%s: nlmsg_rx", __func__);
+		return (-1);
+	}
+	if ((ok = nl_parse_reply(reply, (size_t)r, GENL_ID_CTRL,
+	    CTRL_CMD_NEWFAMILY, &family, parse_family)) != 0) {
+		fido_log_debug("%s: nl_parse_reply: %d", __func__, ok);
+		return (-1);
+	}
+	if (family.id == 0 || family.mcastgrp == 0) {
+		fido_log_debug("%s: missing attr", __func__);
+		return (-1);
+	}
+	*type = family.id;
+	*mcastgrp = family.mcastgrp;
+
+	return (0);
+}
+
+static int
+parse_target(nlamsgbuf_t *a, void *arg)
+{
+	nl_target_t *t = arg;
+
+	if (t->found || nla_type(a) != NFC_ATTR_TARGET_INDEX) {
+		fido_log_debug("%s: ignoring nla 0x%x", __func__, nla_type(a));
+		return (0);
+	}
+	if (nla_get_u32(a, t->value) < 0) {
+		fido_log_debug("%s: target", __func__);
+		return (-1);
+	}
+	t->found = 1;
+
+	return (0);
+}
+
+int
+fido_nl_power_nfc(fido_nl_t *nl, uint32_t dev)
+{
+	nlmsgbuf_t *m;
+	uint8_t reply[512];
+	ssize_t r;
+	int ok;
+
+	if ((m = nlmsg_new(nl->nfc_type, NLM_F_ACK, 64)) == NULL ||
+	    nlmsg_set_genl(m, NFC_CMD_DEV_UP) < 0 ||
+	    nlmsg_set_u32(m, NFC_ATTR_DEVICE_INDEX, dev) < 0 ||
+	    nlmsg_tx(nl->fd, m) < 0) {
+		free(m);
+		return (-1);
+	}
+	free(m);
+	if ((r = nlmsg_rx(nl->fd, reply, sizeof(reply), -1)) < 0) {
+		fido_log_debug("%s: nlmsg_rx", __func__);
+		return (-1);
+	}
+	if ((ok = nl_parse_reply(reply, (size_t)r, nl->nfc_type,
+	    NFC_CMD_DEV_UP, NULL, NULL)) != 0 && ok != EALREADY) {
+		fido_log_debug("%s: nl_parse_reply: %d", __func__, ok);
+		return (-1);
+	}
+
+	return (0);
+}
+
+static int
+nl_nfc_poll(fido_nl_t *nl, uint32_t dev)
+{
+	nlmsgbuf_t *m;
+	uint8_t reply[512];
+	ssize_t r;
+	int ok;
+
+	if ((m = nlmsg_new(nl->nfc_type, NLM_F_ACK, 64)) == NULL ||
+	    nlmsg_set_genl(m, NFC_CMD_START_POLL) < 0 ||
+	    nlmsg_set_u32(m, NFC_ATTR_DEVICE_INDEX, dev) < 0 ||
+	    nlmsg_set_u32(m, NFC_ATTR_PROTOCOLS, NFC_PROTO_ISO14443_MASK) < 0 ||
+	    nlmsg_tx(nl->fd, m) < 0) {
+		free(m);
+		return (-1);
+	}
+	free(m);
+	if ((r = nlmsg_rx(nl->fd, reply, sizeof(reply), -1)) < 0) {
+		fido_log_debug("%s: nlmsg_rx", __func__);
+		return (-1);
+	}
+	if ((ok = nl_parse_reply(reply, (size_t)r, nl->nfc_type,
+	    NFC_CMD_START_POLL, NULL, NULL)) != 0) {
+		fido_log_debug("%s: nl_parse_reply: %d", __func__, ok);
+		return (-1);
+	}
+
+	return (0);
+}
+
+static int
+nl_dump_nfc_target(fido_nl_t *nl, uint32_t dev, uint32_t *target, int ms)
+{
+	nlmsgbuf_t *m;
+	nl_target_t t;
+	uint8_t reply[512];
+	ssize_t r;
+	int ok;
+
+	if ((m = nlmsg_new(nl->nfc_type, NLM_F_DUMP, 64)) == NULL ||
+	    nlmsg_set_genl(m, NFC_CMD_GET_TARGET) < 0 ||
+	    nlmsg_set_u32(m, NFC_ATTR_DEVICE_INDEX, dev) < 0 ||
+	    nlmsg_tx(nl->fd, m) < 0) {
+		free(m);
+		return (-1);
+	}
+	free(m);
+	if ((r = nlmsg_rx(nl->fd, reply, sizeof(reply), ms)) < 0) {
+		fido_log_debug("%s: nlmsg_rx", __func__);
+		return (-1);
+	}
+	memset(&t, 0, sizeof(t));
+	t.value = target;
+	if ((ok = nl_parse_reply(reply, (size_t)r, nl->nfc_type,
+	    NFC_CMD_GET_TARGET, &t, parse_target)) != 0) {
+		fido_log_debug("%s: nl_parse_reply: %d", __func__, ok);
+		return (-1);
+	}
+	if (!t.found) {
+		fido_log_debug("%s: target not found", __func__);
+		return (-1);
+	}
+
+	return (0);
+}
+
+static int
+parse_nfc_event(nlamsgbuf_t *a, void *arg)
+{
+	nl_poll_t *ctx = arg;
+	uint32_t dev;
+
+	if (nla_type(a) != NFC_ATTR_DEVICE_INDEX) {
+		fido_log_debug("%s: ignoring nla 0x%x", __func__, nla_type(a));
+		return (0);
+	}
+	if (nla_get_u32(a, &dev) < 0) {
+		fido_log_debug("%s: dev", __func__);
+		return (-1);
+	}
+	if (dev == ctx->dev)
+		ctx->eventcnt++;
+	else
+		fido_log_debug("%s: ignoring dev 0x%x", __func__, dev);
+
+	return (0);
+}
+
+int
+fido_nl_get_nfc_target(fido_nl_t *nl, uint32_t dev, uint32_t *target)
+{
+	uint8_t reply[512];
+	nl_poll_t ctx;
+	ssize_t r;
+	int ok;
+
+	if (nl_nfc_poll(nl, dev) < 0) {
+		fido_log_debug("%s: nl_nfc_poll", __func__);
+		return (-1);
+	}
+#ifndef FIDO_FUZZ
+	if (setsockopt(nl->fd, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP,
+	    &nl->nfc_mcastgrp, sizeof(nl->nfc_mcastgrp)) == -1) {
+		fido_log_error(errno, "%s: setsockopt add", __func__);
+		return (-1);
+	}
+#endif
+	r = nlmsg_rx(nl->fd, reply, sizeof(reply), NETLINK_POLL_MS);
+#ifndef FIDO_FUZZ
+	if (setsockopt(nl->fd, SOL_NETLINK, NETLINK_DROP_MEMBERSHIP,
+	    &nl->nfc_mcastgrp, sizeof(nl->nfc_mcastgrp)) == -1) {
+		fido_log_error(errno, "%s: setsockopt drop", __func__);
+		return (-1);
+	}
+#endif
+	if (r < 0) {
+		fido_log_debug("%s: nlmsg_rx", __func__);
+		return (-1);
+	}
+	memset(&ctx, 0, sizeof(ctx));
+	ctx.dev = dev;
+	if ((ok = nl_parse_reply(reply, (size_t)r, nl->nfc_type,
+	    NFC_EVENT_TARGETS_FOUND, &ctx, parse_nfc_event)) != 0) {
+		fido_log_debug("%s: nl_parse_reply: %d", __func__, ok);
+		return (-1);
+	}
+	if (ctx.eventcnt == 0) {
+		fido_log_debug("%s: dev 0x%x not observed", __func__, dev);
+		return (-1);
+	}
+	if (nl_dump_nfc_target(nl, dev, target, -1) < 0) {
+		fido_log_debug("%s: nl_dump_nfc_target", __func__);
+		return (-1);
+	}
+
+	return (0);
+}
+
+void
+fido_nl_free(fido_nl_t **nlp)
+{
+	fido_nl_t *nl;
+
+	if (nlp == NULL || (nl = *nlp) == NULL)
+		return;
+	if (nl->fd != -1 && close(nl->fd) == -1)
+		fido_log_error(errno, "%s: close", __func__);
+
+	free(nl);
+	*nlp = NULL;
+}
+
+fido_nl_t *
+fido_nl_new(void)
+{
+	fido_nl_t *nl;
+	int ok = -1;
+
+	if ((nl = calloc(1, sizeof(*nl))) == NULL)
+		return (NULL);
+	if ((nl->fd = socket(AF_NETLINK, SOCK_RAW | SOCK_CLOEXEC,
+	    NETLINK_GENERIC)) == -1) {
+		fido_log_error(errno, "%s: socket", __func__);
+		goto fail;
+	}
+	nl->saddr.nl_family = AF_NETLINK;
+	if (bind(nl->fd, (struct sockaddr *)&nl->saddr,
+	    sizeof(nl->saddr)) == -1) {
+		fido_log_error(errno, "%s: bind", __func__);
+		goto fail;
+	}
+	if (nl_get_nfc_family(nl->fd, &nl->nfc_type, &nl->nfc_mcastgrp) < 0) {
+		fido_log_debug("%s: nl_get_nfc_family", __func__);
+		goto fail;
+	}
+
+	ok = 0;
+fail:
+	if (ok < 0)
+		fido_nl_free(&nl);
+
+	return (nl);
+}
+
+#ifdef FIDO_FUZZ
+void
+set_netlink_io_functions(ssize_t (*read_f)(int, void *, size_t),
+    ssize_t (*write_f)(int, const void *, size_t))
+{
+	fuzz_read = read_f;
+	fuzz_write = write_f;
+}
+#endif