merge udev/, libudev/, systemd/ files in src/; move extras/ to src/

1 files changed, 875 insertions, 0 deletions

diff --git a/src/libudev-monitor.c b/src/libudev-monitor.c
new file mode 100644
index 0000000000..f2f39f9582
--- /dev/null
+++ b/src/libudev-monitor.c
@@ -0,0 +1,875 @@
+/*
+ * libudev - interface to udev device information
+ *
+ * Copyright (C) 2008-2010 Kay Sievers <kay.sievers@vrfy.org>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stddef.h>
+#include <unistd.h>
+#include <errno.h>
+#include <string.h>
+#include <dirent.h>
+#include <sys/poll.h>
+#include <sys/stat.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <arpa/inet.h>
+#include <linux/netlink.h>
+#include <linux/filter.h>
+
+#include "libudev.h"
+#include "libudev-private.h"
+
+/**
+ * SECTION:libudev-monitor
+ * @short_description: device event source
+ *
+ * Connects to a device event source.
+ */
+
+/**
+ * udev_monitor:
+ *
+ * Opaque object handling an event source.
+ */
+struct udev_monitor {
+	struct udev *udev;
+	int refcount;
+	int sock;
+	struct sockaddr_nl snl;
+	struct sockaddr_nl snl_trusted_sender;
+	struct sockaddr_nl snl_destination;
+	struct sockaddr_un sun;
+	socklen_t addrlen;
+	struct udev_list filter_subsystem_list;
+	struct udev_list filter_tag_list;
+	bool bound;
+};
+
+enum udev_monitor_netlink_group {
+	UDEV_MONITOR_NONE,
+	UDEV_MONITOR_KERNEL,
+	UDEV_MONITOR_UDEV,
+};
+
+#define UDEV_MONITOR_MAGIC		0xfeedcafe
+struct udev_monitor_netlink_header {
+	/* "libudev" prefix to distinguish libudev and kernel messages */
+	char prefix[8];
+	/*
+	 * magic to protect against daemon <-> library message format mismatch
+	 * used in the kernel from socket filter rules; needs to be stored in network order
+	 */
+	unsigned int magic;
+	/* total length of header structure known to the sender */
+	unsigned int header_size;
+	/* properties string buffer */
+	unsigned int properties_off;
+	unsigned int properties_len;
+	/*
+	 * hashes of primary device properties strings, to let libudev subscribers
+	 * use in-kernel socket filters; values need to be stored in network order
+	 */
+	unsigned int filter_subsystem_hash;
+	unsigned int filter_devtype_hash;
+	unsigned int filter_tag_bloom_hi;
+	unsigned int filter_tag_bloom_lo;
+};
+
+static struct udev_monitor *udev_monitor_new(struct udev *udev)
+{
+	struct udev_monitor *udev_monitor;
+
+	udev_monitor = calloc(1, sizeof(struct udev_monitor));
+	if (udev_monitor == NULL)
+		return NULL;
+	udev_monitor->refcount = 1;
+	udev_monitor->udev = udev;
+	udev_list_init(udev, &udev_monitor->filter_subsystem_list, false);
+	udev_list_init(udev, &udev_monitor->filter_tag_list, true);
+	return udev_monitor;
+}
+
+/**
+ * udev_monitor_new_from_socket:
+ * @udev: udev library context
+ * @socket_path: unix socket path
+ *
+ * This function should not be used in any new application. The
+ * kernel's netlink socket multiplexes messages to all interested
+ * clients. Creating custom sockets from udev to applications
+ * should be avoided.
+ *
+ * Create a new udev monitor and connect to a specified socket. The
+ * path to a socket either points to an existing socket file, or if
+ * the socket path starts with a '@' character, an abstract namespace
+ * socket will be used.
+ *
+ * A socket file will not be created. If it does not already exist,
+ * it will fall-back and connect to an abstract namespace socket with
+ * the given path. The permissions adjustment of a socket file, as
+ * well as the later cleanup, needs to be done by the caller.
+ *
+ * The initial refcount is 1, and needs to be decremented to
+ * release the resources of the udev monitor.
+ *
+ * Returns: a new udev monitor, or #NULL, in case of an error
+ **/
+UDEV_EXPORT struct udev_monitor *udev_monitor_new_from_socket(struct udev *udev, const char *socket_path)
+{
+	struct udev_monitor *udev_monitor;
+	struct stat statbuf;
+
+	if (udev == NULL)
+		return NULL;
+	if (socket_path == NULL)
+		return NULL;
+	udev_monitor = udev_monitor_new(udev);
+	if (udev_monitor == NULL)
+		return NULL;
+
+	udev_monitor->sun.sun_family = AF_LOCAL;
+	if (socket_path[0] == '@') {
+		/* translate leading '@' to abstract namespace */
+		util_strscpy(udev_monitor->sun.sun_path, sizeof(udev_monitor->sun.sun_path), socket_path);
+		udev_monitor->sun.sun_path[0] = '\0';
+		udev_monitor->addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(socket_path);
+	} else if (stat(socket_path, &statbuf) == 0 && S_ISSOCK(statbuf.st_mode)) {
+		/* existing socket file */
+		util_strscpy(udev_monitor->sun.sun_path, sizeof(udev_monitor->sun.sun_path), socket_path);
+		udev_monitor->addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(socket_path);
+	} else {
+		/* no socket file, assume abstract namespace socket */
+		util_strscpy(&udev_monitor->sun.sun_path[1], sizeof(udev_monitor->sun.sun_path)-1, socket_path);
+		udev_monitor->addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(socket_path)+1;
+	}
+	udev_monitor->sock = socket(AF_LOCAL, SOCK_DGRAM|SOCK_NONBLOCK|SOCK_CLOEXEC, 0);
+	if (udev_monitor->sock == -1) {
+		err(udev, "error getting socket: %m\n");
+		free(udev_monitor);
+		return NULL;
+	}
+
+	dbg(udev, "monitor %p created with '%s'\n", udev_monitor, socket_path);
+	return udev_monitor;
+}
+
+struct udev_monitor *udev_monitor_new_from_netlink_fd(struct udev *udev, const char *name, int fd)
+{
+	struct udev_monitor *udev_monitor;
+	unsigned int group;
+
+	if (udev == NULL)
+		return NULL;
+
+	if (name == NULL)
+		group = UDEV_MONITOR_NONE;
+	else if (strcmp(name, "udev") == 0)
+		group = UDEV_MONITOR_UDEV;
+	else if (strcmp(name, "kernel") == 0)
+		group = UDEV_MONITOR_KERNEL;
+	else
+		return NULL;
+
+	udev_monitor = udev_monitor_new(udev);
+	if (udev_monitor == NULL)
+		return NULL;
+
+	if (fd < 0) {
+		udev_monitor->sock = socket(PF_NETLINK, SOCK_RAW|SOCK_CLOEXEC|SOCK_NONBLOCK, NETLINK_KOBJECT_UEVENT);
+		if (udev_monitor->sock == -1) {
+			err(udev, "error getting socket: %m\n");
+			free(udev_monitor);
+			return NULL;
+		}
+	} else {
+		udev_monitor->bound = true;
+		udev_monitor->sock = fd;
+	}
+
+	udev_monitor->snl.nl_family = AF_NETLINK;
+	udev_monitor->snl.nl_groups = group;
+
+	/* default destination for sending */
+	udev_monitor->snl_destination.nl_family = AF_NETLINK;
+	udev_monitor->snl_destination.nl_groups = UDEV_MONITOR_UDEV;
+
+	dbg(udev, "monitor %p created with NETLINK_KOBJECT_UEVENT (%u)\n", udev_monitor, group);
+	return udev_monitor;
+}
+
+/**
+ * udev_monitor_new_from_netlink:
+ * @udev: udev library context
+ * @name: name of event source
+ *
+ * Create new udev monitor and connect to a specified event
+ * source. Valid sources identifiers are "udev" and "kernel".
+ *
+ * Applications should usually not connect directly to the
+ * "kernel" events, because the devices might not be useable
+ * at that time, before udev has configured them, and created
+ * device nodes. Accessing devices at the same time as udev,
+ * might result in unpredictable behavior. The "udev" events
+ * are sent out after udev has finished its event processing,
+ * all rules have been processed, and needed device nodes are
+ * created.
+ *
+ * The initial refcount is 1, and needs to be decremented to
+ * release the resources of the udev monitor.
+ *
+ * Returns: a new udev monitor, or #NULL, in case of an error
+ **/
+UDEV_EXPORT struct udev_monitor *udev_monitor_new_from_netlink(struct udev *udev, const char *name)
+{
+	return udev_monitor_new_from_netlink_fd(udev, name, -1);
+}
+
+static inline void bpf_stmt(struct sock_filter *inss, unsigned int *i,
+			    unsigned short code, unsigned int data)
+{
+	struct sock_filter *ins = &inss[*i];
+
+	ins->code = code;
+	ins->k = data;
+	(*i)++;
+}
+
+static inline void bpf_jmp(struct sock_filter *inss, unsigned int *i,
+			   unsigned short code, unsigned int data,
+			   unsigned short jt, unsigned short jf)
+{
+	struct sock_filter *ins = &inss[*i];
+
+	ins->code = code;
+	ins->jt = jt;
+	ins->jf = jf;
+	ins->k = data;
+	(*i)++;
+}
+
+/**
+ * udev_monitor_filter_update:
+ * @udev_monitor: monitor
+ *
+ * Update the installed socket filter. This is only needed,
+ * if the filter was removed or changed.
+ *
+ * Returns: 0 on success, otherwise a negative error value.
+ */
+UDEV_EXPORT int udev_monitor_filter_update(struct udev_monitor *udev_monitor)
+{
+	struct sock_filter ins[512];
+	struct sock_fprog filter;
+	unsigned int i;
+	struct udev_list_entry *list_entry;
+	int err;
+
+	if (udev_list_get_entry(&udev_monitor->filter_subsystem_list) == NULL &&
+	    udev_list_get_entry(&udev_monitor->filter_tag_list) == NULL)
+		return 0;
+
+	memset(ins, 0x00, sizeof(ins));
+	i = 0;
+
+	/* load magic in A */
+	bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, magic));
+	/* jump if magic matches */
+	bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, UDEV_MONITOR_MAGIC, 1, 0);
+	/* wrong magic, pass packet */
+	bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff);
+
+	if (udev_list_get_entry(&udev_monitor->filter_tag_list) != NULL) {
+		int tag_matches;
+
+		/* count tag matches, to calculate end of tag match block */
+		tag_matches = 0;
+		udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_tag_list))
+			tag_matches++;
+
+		/* add all tags matches */
+		udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_tag_list)) {
+			uint64_t tag_bloom_bits = util_string_bloom64(udev_list_entry_get_name(list_entry));
+			uint32_t tag_bloom_hi = tag_bloom_bits >> 32;
+			uint32_t tag_bloom_lo = tag_bloom_bits & 0xffffffff;
+
+			/* load device bloom bits in A */
+			bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_tag_bloom_hi));
+			/* clear bits (tag bits & bloom bits) */
+			bpf_stmt(ins, &i, BPF_ALU|BPF_AND|BPF_K, tag_bloom_hi);
+			/* jump to next tag if it does not match */
+			bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, tag_bloom_hi, 0, 3);
+
+			/* load device bloom bits in A */
+			bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_tag_bloom_lo));
+			/* clear bits (tag bits & bloom bits) */
+			bpf_stmt(ins, &i, BPF_ALU|BPF_AND|BPF_K, tag_bloom_lo);
+			/* jump behind end of tag match block if tag matches */
+			tag_matches--;
+			bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, tag_bloom_lo, 1 + (tag_matches * 6), 0);
+		}
+
+		/* nothing matched, drop packet */
+		bpf_stmt(ins, &i, BPF_RET|BPF_K, 0);
+	}
+
+	/* add all subsystem matches */
+	if (udev_list_get_entry(&udev_monitor->filter_subsystem_list) != NULL) {
+		udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_subsystem_list)) {
+			unsigned int hash = util_string_hash32(udev_list_entry_get_name(list_entry));
+
+			/* load device subsystem value in A */
+			bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_subsystem_hash));
+			if (udev_list_entry_get_value(list_entry) == NULL) {
+				/* jump if subsystem does not match */
+				bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 1);
+			} else {
+				/* jump if subsystem does not match */
+				bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 3);
+
+				/* load device devtype value in A */
+				bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_devtype_hash));
+				/* jump if value does not match */
+				hash = util_string_hash32(udev_list_entry_get_value(list_entry));
+				bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 1);
+			}
+
+			/* matched, pass packet */
+			bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff);
+
+			if (i+1 >= ARRAY_SIZE(ins))
+				return -1;
+		}
+
+		/* nothing matched, drop packet */
+		bpf_stmt(ins, &i, BPF_RET|BPF_K, 0);
+	}
+
+	/* matched, pass packet */
+	bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff);
+
+	/* install filter */
+	memset(&filter, 0x00, sizeof(filter));
+	filter.len = i;
+	filter.filter = ins;
+	err = setsockopt(udev_monitor->sock, SOL_SOCKET, SO_ATTACH_FILTER, &filter, sizeof(filter));
+	return err;
+}
+
+int udev_monitor_allow_unicast_sender(struct udev_monitor *udev_monitor, struct udev_monitor *sender)
+{
+	udev_monitor->snl_trusted_sender.nl_pid = sender->snl.nl_pid;
+	return 0;
+}
+/**
+ * udev_monitor_enable_receiving:
+ * @udev_monitor: the monitor which should receive events
+ *
+ * Binds the @udev_monitor socket to the event source.
+ *
+ * Returns: 0 on success, otherwise a negative error value.
+ */
+UDEV_EXPORT int udev_monitor_enable_receiving(struct udev_monitor *udev_monitor)
+{
+	int err = 0;
+	const int on = 1;
+
+	if (udev_monitor->sun.sun_family != 0) {
+		if (!udev_monitor->bound) {
+			err = bind(udev_monitor->sock,
+				   (struct sockaddr *)&udev_monitor->sun, udev_monitor->addrlen);
+			if (err == 0)
+				udev_monitor->bound = true;
+		}
+	} else if (udev_monitor->snl.nl_family != 0) {
+		udev_monitor_filter_update(udev_monitor);
+		if (!udev_monitor->bound) {
+			err = bind(udev_monitor->sock,
+				   (struct sockaddr *)&udev_monitor->snl, sizeof(struct sockaddr_nl));
+			if (err == 0)
+				udev_monitor->bound = true;
+		}
+		if (err == 0) {
+			struct sockaddr_nl snl;
+			socklen_t addrlen;
+
+			/*
+			 * get the address the kernel has assigned us
+			 * it is usually, but not necessarily the pid
+			 */
+			addrlen = sizeof(struct sockaddr_nl);
+			err = getsockname(udev_monitor->sock, (struct sockaddr *)&snl, &addrlen);
+			if (err == 0)
+				udev_monitor->snl.nl_pid = snl.nl_pid;
+		}
+	} else {
+		return -EINVAL;
+	}
+
+	if (err < 0) {
+		err(udev_monitor->udev, "bind failed: %m\n");
+		return err;
+	}
+
+	/* enable receiving of sender credentials */
+	setsockopt(udev_monitor->sock, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on));
+	return 0;
+}
+
+/**
+ * udev_monitor_set_receive_buffer_size:
+ * @udev_monitor: the monitor which should receive events
+ * @size: the size in bytes
+ *
+ * Set the size of the kernel socket buffer. This call needs the
+ * appropriate privileges to succeed.
+ *
+ * Returns: 0 on success, otherwise -1 on error.
+ */
+UDEV_EXPORT int udev_monitor_set_receive_buffer_size(struct udev_monitor *udev_monitor, int size)
+{
+	if (udev_monitor == NULL)
+		return -1;
+	return setsockopt(udev_monitor->sock, SOL_SOCKET, SO_RCVBUFFORCE, &size, sizeof(size));
+}
+
+int udev_monitor_disconnect(struct udev_monitor *udev_monitor)
+{
+	int err;
+
+	err = close(udev_monitor->sock);
+	udev_monitor->sock = -1;
+	return err;
+}
+
+/**
+ * udev_monitor_ref:
+ * @udev_monitor: udev monitor
+ *
+ * Take a reference of a udev monitor.
+ *
+ * Returns: the passed udev monitor
+ **/
+UDEV_EXPORT struct udev_monitor *udev_monitor_ref(struct udev_monitor *udev_monitor)
+{
+	if (udev_monitor == NULL)
+		return NULL;
+	udev_monitor->refcount++;
+	return udev_monitor;
+}
+
+/**
+ * udev_monitor_unref:
+ * @udev_monitor: udev monitor
+ *
+ * Drop a reference of a udev monitor. If the refcount reaches zero,
+ * the bound socket will be closed, and the resources of the monitor
+ * will be released.
+ *
+ **/
+UDEV_EXPORT void udev_monitor_unref(struct udev_monitor *udev_monitor)
+{
+	if (udev_monitor == NULL)
+		return;
+	udev_monitor->refcount--;
+	if (udev_monitor->refcount > 0)
+		return;
+	if (udev_monitor->sock >= 0)
+		close(udev_monitor->sock);
+	udev_list_cleanup(&udev_monitor->filter_subsystem_list);
+	udev_list_cleanup(&udev_monitor->filter_tag_list);
+	dbg(udev_monitor->udev, "monitor %p released\n", udev_monitor);
+	free(udev_monitor);
+}
+
+/**
+ * udev_monitor_get_udev:
+ * @udev_monitor: udev monitor
+ *
+ * Retrieve the udev library context the monitor was created with.
+ *
+ * Returns: the udev library context
+ **/
+UDEV_EXPORT struct udev *udev_monitor_get_udev(struct udev_monitor *udev_monitor)
+{
+	if (udev_monitor == NULL)
+		return NULL;
+	return udev_monitor->udev;
+}
+
+/**
+ * udev_monitor_get_fd:
+ * @udev_monitor: udev monitor
+ *
+ * Retrieve the socket file descriptor associated with the monitor.
+ *
+ * Returns: the socket file descriptor
+ **/
+UDEV_EXPORT int udev_monitor_get_fd(struct udev_monitor *udev_monitor)
+{
+	if (udev_monitor == NULL)
+		return -1;
+	return udev_monitor->sock;
+}
+
+static int passes_filter(struct udev_monitor *udev_monitor, struct udev_device *udev_device)
+{
+	struct udev_list_entry *list_entry;
+
+	if (udev_list_get_entry(&udev_monitor->filter_subsystem_list) == NULL)
+		goto tag;
+	udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_subsystem_list)) {
+		const char *subsys = udev_list_entry_get_name(list_entry);
+		const char *dsubsys = udev_device_get_subsystem(udev_device);
+		const char *devtype;
+		const char *ddevtype;
+
+		if (strcmp(dsubsys, subsys) != 0)
+			continue;
+
+		devtype = udev_list_entry_get_value(list_entry);
+		if (devtype == NULL)
+			goto tag;
+		ddevtype = udev_device_get_devtype(udev_device);
+		if (ddevtype == NULL)
+			continue;
+		if (strcmp(ddevtype, devtype) == 0)
+			goto tag;
+	}
+	return 0;
+
+tag:
+	if (udev_list_get_entry(&udev_monitor->filter_tag_list) == NULL)
+		return 1;
+	udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_tag_list)) {
+		const char *tag = udev_list_entry_get_name(list_entry);
+
+		if (udev_device_has_tag(udev_device, tag))
+			return 1;
+	}
+	return 0;
+}
+
+/**
+ * udev_monitor_receive_device:
+ * @udev_monitor: udev monitor
+ *
+ * Receive data from the udev monitor socket, allocate a new udev
+ * device, fill in the received data, and return the device.
+ *
+ * Only socket connections with uid=0 are accepted.
+ *
+ * The initial refcount is 1, and needs to be decremented to
+ * release the resources of the udev device.
+ *
+ * Returns: a new udev device, or #NULL, in case of an error
+ **/
+UDEV_EXPORT struct udev_device *udev_monitor_receive_device(struct udev_monitor *udev_monitor)
+{
+	struct udev_device *udev_device;
+	struct msghdr smsg;
+	struct iovec iov;
+	char cred_msg[CMSG_SPACE(sizeof(struct ucred))];
+	struct cmsghdr *cmsg;
+	struct sockaddr_nl snl;
+	struct ucred *cred;
+	char buf[8192];
+	ssize_t buflen;
+	ssize_t bufpos;
+	struct udev_monitor_netlink_header *nlh;
+
+retry:
+	if (udev_monitor == NULL)
+		return NULL;
+	memset(buf, 0x00, sizeof(buf));
+	iov.iov_base = &buf;
+	iov.iov_len = sizeof(buf);
+	memset (&smsg, 0x00, sizeof(struct msghdr));
+	smsg.msg_iov = &iov;
+	smsg.msg_iovlen = 1;
+	smsg.msg_control = cred_msg;
+	smsg.msg_controllen = sizeof(cred_msg);
+
+	if (udev_monitor->snl.nl_family != 0) {
+		smsg.msg_name = &snl;
+		smsg.msg_namelen = sizeof(snl);
+	}
+
+	buflen = recvmsg(udev_monitor->sock, &smsg, 0);
+	if (buflen < 0) {
+		if (errno != EINTR)
+			info(udev_monitor->udev, "unable to receive message\n");
+		return NULL;
+	}
+
+	if (buflen < 32 || (size_t)buflen >= sizeof(buf)) {
+		info(udev_monitor->udev, "invalid message length\n");
+		return NULL;
+	}
+
+	if (udev_monitor->snl.nl_family != 0) {
+		if (snl.nl_groups == 0) {
+			/* unicast message, check if we trust the sender */
+			if (udev_monitor->snl_trusted_sender.nl_pid == 0 ||
+			    snl.nl_pid != udev_monitor->snl_trusted_sender.nl_pid) {
+				info(udev_monitor->udev, "unicast netlink message ignored\n");
+				return NULL;
+			}
+		} else if (snl.nl_groups == UDEV_MONITOR_KERNEL) {
+			if (snl.nl_pid > 0) {
+				info(udev_monitor->udev, "multicast kernel netlink message from pid %d ignored\n",
+				     snl.nl_pid);
+				return NULL;
+			}
+		}
+	}
+
+	cmsg = CMSG_FIRSTHDR(&smsg);
+	if (cmsg == NULL || cmsg->cmsg_type != SCM_CREDENTIALS) {
+		info(udev_monitor->udev, "no sender credentials received, message ignored\n");
+		return NULL;
+	}
+
+	cred = (struct ucred *)CMSG_DATA(cmsg);
+	if (cred->uid != 0) {
+		info(udev_monitor->udev, "sender uid=%d, message ignored\n", cred->uid);
+		return NULL;
+	}
+
+	if (memcmp(buf, "libudev", 8) == 0) {
+		/* udev message needs proper version magic */
+		nlh = (struct udev_monitor_netlink_header *) buf;
+		if (nlh->magic != htonl(UDEV_MONITOR_MAGIC)) {
+			err(udev_monitor->udev, "unrecognized message signature (%x != %x)\n",
+			    nlh->magic, htonl(UDEV_MONITOR_MAGIC));
+			return NULL;
+		}
+		if (nlh->properties_off+32 > buflen)
+			return NULL;
+		bufpos = nlh->properties_off;
+	} else {
+		/* kernel message with header */
+		bufpos = strlen(buf) + 1;
+		if ((size_t)bufpos < sizeof("a@/d") || bufpos >= buflen) {
+			info(udev_monitor->udev, "invalid message length\n");
+			return NULL;
+		}
+
+		/* check message header */
+		if (strstr(buf, "@/") == NULL) {
+			info(udev_monitor->udev, "unrecognized message header\n");
+			return NULL;
+		}
+	}
+
+	udev_device = udev_device_new(udev_monitor->udev);
+	if (udev_device == NULL)
+		return NULL;
+	udev_device_set_info_loaded(udev_device);
+
+	while (bufpos < buflen) {
+		char *key;
+		size_t keylen;
+
+		key = &buf[bufpos];
+		keylen = strlen(key);
+		if (keylen == 0)
+			break;
+		bufpos += keylen + 1;
+		udev_device_add_property_from_string_parse(udev_device, key);
+	}
+
+	if (udev_device_add_property_from_string_parse_finish(udev_device) < 0) {
+		info(udev_monitor->udev, "missing values, invalid device\n");
+		udev_device_unref(udev_device);
+		return NULL;
+	}
+
+	/* skip device, if it does not pass the current filter */
+	if (!passes_filter(udev_monitor, udev_device)) {
+		struct pollfd pfd[1];
+		int rc;
+
+		udev_device_unref(udev_device);
+
+		/* if something is queued, get next device */
+		pfd[0].fd = udev_monitor->sock;
+		pfd[0].events = POLLIN;
+		rc = poll(pfd, 1, 0);
+		if (rc > 0)
+			goto retry;
+		return NULL;
+	}
+
+	return udev_device;
+}
+
+int udev_monitor_send_device(struct udev_monitor *udev_monitor,
+			     struct udev_monitor *destination, struct udev_device *udev_device)
+{
+	const char *buf;
+	ssize_t blen;
+	ssize_t count;
+
+	blen = udev_device_get_properties_monitor_buf(udev_device, &buf);
+	if (blen < 32)
+		return -EINVAL;
+
+	if (udev_monitor->sun.sun_family != 0) {
+		struct msghdr smsg;
+		struct iovec iov[2];
+		const char *action;
+		char header[2048];
+		char *s;
+
+		/* header <action>@<devpath> */
+		action = udev_device_get_action(udev_device);
+		if (action == NULL)
+			return -EINVAL;
+		s = header;
+		if (util_strpcpyl(&s, sizeof(header), action, "@", udev_device_get_devpath(udev_device), NULL) == 0)
+			return -EINVAL;
+		iov[0].iov_base = header;
+		iov[0].iov_len = (s - header)+1;
+
+		/* add properties list */
+		iov[1].iov_base = (char *)buf;
+		iov[1].iov_len = blen;
+
+		memset(&smsg, 0x00, sizeof(struct msghdr));
+		smsg.msg_iov = iov;
+		smsg.msg_iovlen = 2;
+		smsg.msg_name = &udev_monitor->sun;
+		smsg.msg_namelen = udev_monitor->addrlen;
+		count = sendmsg(udev_monitor->sock, &smsg, 0);
+		info(udev_monitor->udev, "passed %zi bytes to socket monitor %p\n", count, udev_monitor);
+		return count;
+	}
+
+	if (udev_monitor->snl.nl_family != 0) {
+		struct msghdr smsg;
+		struct iovec iov[2];
+		const char *val;
+		struct udev_monitor_netlink_header nlh;
+		struct udev_list_entry *list_entry;
+		uint64_t tag_bloom_bits;
+
+		/* add versioned header */
+		memset(&nlh, 0x00, sizeof(struct udev_monitor_netlink_header));
+		memcpy(nlh.prefix, "libudev", 8);
+		nlh.magic = htonl(UDEV_MONITOR_MAGIC);
+		nlh.header_size = sizeof(struct udev_monitor_netlink_header);
+		val = udev_device_get_subsystem(udev_device);
+		nlh.filter_subsystem_hash = htonl(util_string_hash32(val));
+		val = udev_device_get_devtype(udev_device);
+		if (val != NULL)
+			nlh.filter_devtype_hash = htonl(util_string_hash32(val));
+		iov[0].iov_base = &nlh;
+		iov[0].iov_len = sizeof(struct udev_monitor_netlink_header);
+
+		/* add tag bloom filter */
+		tag_bloom_bits = 0;
+		udev_list_entry_foreach(list_entry, udev_device_get_tags_list_entry(udev_device))
+			tag_bloom_bits |= util_string_bloom64(udev_list_entry_get_name(list_entry));
+		if (tag_bloom_bits > 0) {
+			nlh.filter_tag_bloom_hi = htonl(tag_bloom_bits >> 32);
+			nlh.filter_tag_bloom_lo = htonl(tag_bloom_bits & 0xffffffff);
+		}
+
+		/* add properties list */
+		nlh.properties_off = iov[0].iov_len;
+		nlh.properties_len = blen;
+		iov[1].iov_base = (char *)buf;
+		iov[1].iov_len = blen;
+
+		memset(&smsg, 0x00, sizeof(struct msghdr));
+		smsg.msg_iov = iov;
+		smsg.msg_iovlen = 2;
+		/*
+		 * Use custom address for target, or the default one.
+		 *
+		 * If we send to a multicast group, we will get
+		 * ECONNREFUSED, which is expected.
+		 */
+		if (destination != NULL)
+			smsg.msg_name = &destination->snl;
+		else
+			smsg.msg_name = &udev_monitor->snl_destination;
+		smsg.msg_namelen = sizeof(struct sockaddr_nl);
+		count = sendmsg(udev_monitor->sock, &smsg, 0);
+		info(udev_monitor->udev, "passed %zi bytes to netlink monitor %p\n", count, udev_monitor);
+		return count;
+	}
+
+	return -EINVAL;
+}
+
+/**
+ * udev_monitor_filter_add_match_subsystem_devtype:
+ * @udev_monitor: the monitor
+ * @subsystem: the subsystem value to match the incoming devices against
+ * @devtype: the devtype value to match the incoming devices against
+ *
+ * This filter is efficiently executed inside the kernel, and libudev subscribers
+ * will usually not be woken up for devices which do not match.
+ *
+ * The filter must be installed before the monitor is switched to listening mode.
+ *
+ * Returns: 0 on success, otherwise a negative error value.
+ */
+UDEV_EXPORT int udev_monitor_filter_add_match_subsystem_devtype(struct udev_monitor *udev_monitor, const char *subsystem, const char *devtype)
+{
+	if (udev_monitor == NULL)
+		return -EINVAL;
+	if (subsystem == NULL)
+		return -EINVAL;
+	if (udev_list_entry_add(&udev_monitor->filter_subsystem_list, subsystem, devtype) == NULL)
+		return -ENOMEM;
+	return 0;
+}
+
+/**
+ * udev_monitor_filter_add_match_tag:
+ * @udev_monitor: the monitor
+ * @tag: the name of a tag
+ *
+ * This filter is efficiently executed inside the kernel, and libudev subscribers
+ * will usually not be woken up for devices which do not match.
+ *
+ * The filter must be installed before the monitor is switched to listening mode.
+ *
+ * Returns: 0 on success, otherwise a negative error value.
+ */
+UDEV_EXPORT int udev_monitor_filter_add_match_tag(struct udev_monitor *udev_monitor, const char *tag)
+{
+	if (udev_monitor == NULL)
+		return -EINVAL;
+	if (tag == NULL)
+		return -EINVAL;
+	if (udev_list_entry_add(&udev_monitor->filter_tag_list, tag, NULL) == NULL)
+		return -ENOMEM;
+	return 0;
+}
+
+/**
+ * udev_monitor_filter_remove:
+ * @udev_monitor: monitor
+ *
+ * Remove all filters from monitor.
+ *
+ * Returns: 0 on success, otherwise a negative error value.
+ */
+UDEV_EXPORT int udev_monitor_filter_remove(struct udev_monitor *udev_monitor)
+{
+	static struct sock_fprog filter = { 0, NULL };
+
+	udev_list_cleanup(&udev_monitor->filter_subsystem_list);
+	return setsockopt(udev_monitor->sock, SOL_SOCKET, SO_ATTACH_FILTER, &filter, sizeof(filter));
+}