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-rw-r--r--src/libudev/src/libudev-monitor.c847
1 files changed, 847 insertions, 0 deletions
diff --git a/src/libudev/src/libudev-monitor.c b/src/libudev/src/libudev-monitor.c
new file mode 100644
index 0000000000..71703e927e
--- /dev/null
+++ b/src/libudev/src/libudev-monitor.c
@@ -0,0 +1,847 @@
+/***
+ This file is part of systemd.
+
+ Copyright 2008-2012 Kay Sievers <kay@vrfy.org>
+
+ systemd 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.
+
+ systemd is distributed in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <errno.h>
+#include <poll.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <unistd.h>
+
+#include <linux/filter.h>
+#include <linux/netlink.h>
+
+#include <libudev.h>
+
+#include "systemd-basic/alloc-util.h"
+#include "systemd-basic/fd-util.h"
+#include "systemd-basic/fileio.h"
+#include "systemd-basic/formats-util.h"
+#include "systemd-basic/missing.h"
+#include "systemd-basic/mount-util.h"
+#include "systemd-basic/socket-util.h"
+#include "systemd-basic/string-util.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;
+ union sockaddr_union snl;
+ union sockaddr_union snl_trusted_sender;
+ union sockaddr_union snl_destination;
+ 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 = new0(struct udev_monitor, 1);
+ 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;
+}
+
+/* we consider udev running when /dev is on devtmpfs */
+static bool udev_has_devtmpfs(struct udev *udev) {
+
+ union file_handle_union h = FILE_HANDLE_INIT;
+ _cleanup_fclose_ FILE *f = NULL;
+ char line[LINE_MAX], *e;
+ int mount_id;
+ int r;
+
+ r = name_to_handle_at(AT_FDCWD, "/dev", &h.handle, &mount_id, 0);
+ if (r < 0) {
+ if (errno != EOPNOTSUPP)
+ log_debug_errno(errno, "name_to_handle_at on /dev: %m");
+ return false;
+ }
+
+ f = fopen("/proc/self/mountinfo", "re");
+ if (!f)
+ return false;
+
+ FOREACH_LINE(line, f, return false) {
+ int mid;
+
+ if (sscanf(line, "%i", &mid) != 1)
+ continue;
+
+ if (mid != mount_id)
+ continue;
+
+ e = strstr(line, " - ");
+ if (!e)
+ continue;
+
+ /* accept any name that starts with the currently expected type */
+ if (startswith(e + 3, "devtmpfs"))
+ return true;
+ }
+
+ return false;
+}
+
+static void monitor_set_nl_address(struct udev_monitor *udev_monitor) {
+ union sockaddr_union snl;
+ socklen_t addrlen;
+ int r;
+
+ assert(udev_monitor);
+
+ /* get the address the kernel has assigned us
+ * it is usually, but not necessarily the pid
+ */
+ addrlen = sizeof(struct sockaddr_nl);
+ r = getsockname(udev_monitor->sock, &snl.sa, &addrlen);
+ if (r >= 0)
+ udev_monitor->snl.nl.nl_pid = snl.nl.nl_pid;
+}
+
+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 (streq(name, "udev")) {
+ /*
+ * We do not support subscribing to uevents if no instance of
+ * udev is running. Uevents would otherwise broadcast the
+ * processing data of the host into containers, which is not
+ * desired.
+ *
+ * Containers will currently not get any udev uevents, until
+ * a supporting infrastructure is available.
+ *
+ * We do not set a netlink multicast group here, so the socket
+ * will not receive any messages.
+ */
+ if (access("/run/udev/control", F_OK) < 0 && !udev_has_devtmpfs(udev)) {
+ log_debug("the udev service seems not to be active, disable the monitor");
+ group = UDEV_MONITOR_NONE;
+ } else
+ group = UDEV_MONITOR_UDEV;
+ } else if (streq(name, "kernel"))
+ 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 < 0) {
+ log_debug_errno(errno, "error getting socket: %m");
+ free(udev_monitor);
+ return NULL;
+ }
+ } else {
+ udev_monitor->bound = true;
+ udev_monitor->sock = fd;
+ monitor_set_nl_address(udev_monitor);
+ }
+
+ udev_monitor->snl.nl.nl_family = AF_NETLINK;
+ udev_monitor->snl.nl.nl_groups = group;
+
+ /* default destination for sending */
+ udev_monitor->snl_destination.nl.nl_family = AF_NETLINK;
+ udev_monitor->snl_destination.nl.nl_groups = UDEV_MONITOR_UDEV;
+
+ 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
+ **/
+_public_ 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.
+ */
+_public_ 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;
+
+ memzero(ins, 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 >= ELEMENTSOF(ins))
+ return -E2BIG;
+ }
+
+ /* 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 */
+ memzero(&filter, sizeof(filter));
+ filter.len = i;
+ filter.filter = ins;
+ err = setsockopt(udev_monitor->sock, SOL_SOCKET, SO_ATTACH_FILTER, &filter, sizeof(filter));
+ return err < 0 ? -errno : 0;
+}
+
+int udev_monitor_allow_unicast_sender(struct udev_monitor *udev_monitor, struct udev_monitor *sender)
+{
+ udev_monitor->snl_trusted_sender.nl.nl_pid = sender->snl.nl.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.
+ */
+_public_ int udev_monitor_enable_receiving(struct udev_monitor *udev_monitor)
+{
+ int err = 0;
+ const int on = 1;
+
+ udev_monitor_filter_update(udev_monitor);
+
+ if (!udev_monitor->bound) {
+ err = bind(udev_monitor->sock,
+ &udev_monitor->snl.sa, sizeof(struct sockaddr_nl));
+ if (err == 0)
+ udev_monitor->bound = true;
+ }
+
+ if (err >= 0)
+ monitor_set_nl_address(udev_monitor);
+ else
+ return log_debug_errno(errno, "bind failed: %m");
+
+ /* enable receiving of sender credentials */
+ err = setsockopt(udev_monitor->sock, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on));
+ if (err < 0)
+ log_debug_errno(errno, "setting SO_PASSCRED failed: %m");
+
+ 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.
+ */
+_public_ int udev_monitor_set_receive_buffer_size(struct udev_monitor *udev_monitor, int size)
+{
+ if (udev_monitor == NULL)
+ return -EINVAL;
+ 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 < 0 ? -errno : 0;
+}
+
+/**
+ * udev_monitor_ref:
+ * @udev_monitor: udev monitor
+ *
+ * Take a reference of a udev monitor.
+ *
+ * Returns: the passed udev monitor
+ **/
+_public_ 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.
+ *
+ * Returns: #NULL
+ **/
+_public_ struct udev_monitor *udev_monitor_unref(struct udev_monitor *udev_monitor)
+{
+ if (udev_monitor == NULL)
+ return NULL;
+ udev_monitor->refcount--;
+ if (udev_monitor->refcount > 0)
+ return NULL;
+ 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);
+ free(udev_monitor);
+ return NULL;
+}
+
+/**
+ * udev_monitor_get_udev:
+ * @udev_monitor: udev monitor
+ *
+ * Retrieve the udev library context the monitor was created with.
+ *
+ * Returns: the udev library context
+ **/
+_public_ 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
+ **/
+_public_ int udev_monitor_get_fd(struct udev_monitor *udev_monitor)
+{
+ if (udev_monitor == NULL)
+ return -EINVAL;
+ 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 (!streq(dsubsys, subsys))
+ 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 (streq(ddevtype, devtype))
+ 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 monitor socket is by default set to NONBLOCK. A variant of poll() on
+ * the file descriptor returned by udev_monitor_get_fd() should to be used to
+ * wake up when new devices arrive, or alternatively the file descriptor
+ * switched into blocking mode.
+ *
+ * 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
+ **/
+_public_ 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;
+ union sockaddr_union snl;
+ struct ucred *cred;
+ union {
+ struct udev_monitor_netlink_header nlh;
+ char raw[8192];
+ } buf;
+ ssize_t buflen;
+ ssize_t bufpos;
+ bool is_initialized = false;
+
+retry:
+ if (udev_monitor == NULL)
+ return NULL;
+ iov.iov_base = &buf;
+ iov.iov_len = sizeof(buf);
+ memzero(&smsg, sizeof(struct msghdr));
+ smsg.msg_iov = &iov;
+ smsg.msg_iovlen = 1;
+ smsg.msg_control = cred_msg;
+ smsg.msg_controllen = sizeof(cred_msg);
+ smsg.msg_name = &snl;
+ smsg.msg_namelen = sizeof(snl);
+
+ buflen = recvmsg(udev_monitor->sock, &smsg, 0);
+ if (buflen < 0) {
+ if (errno != EINTR)
+ log_debug("unable to receive message");
+ return NULL;
+ }
+
+ if (buflen < 32 || (smsg.msg_flags & MSG_TRUNC)) {
+ log_debug("invalid message length");
+ return NULL;
+ }
+
+ if (snl.nl.nl_groups == 0) {
+ /* unicast message, check if we trust the sender */
+ if (udev_monitor->snl_trusted_sender.nl.nl_pid == 0 ||
+ snl.nl.nl_pid != udev_monitor->snl_trusted_sender.nl.nl_pid) {
+ log_debug("unicast netlink message ignored");
+ return NULL;
+ }
+ } else if (snl.nl.nl_groups == UDEV_MONITOR_KERNEL) {
+ if (snl.nl.nl_pid > 0) {
+ log_debug("multicast kernel netlink message from PID %"PRIu32" ignored",
+ snl.nl.nl_pid);
+ return NULL;
+ }
+ }
+
+ cmsg = CMSG_FIRSTHDR(&smsg);
+ if (cmsg == NULL || cmsg->cmsg_type != SCM_CREDENTIALS) {
+ log_debug("no sender credentials received, message ignored");
+ return NULL;
+ }
+
+ cred = (struct ucred *)CMSG_DATA(cmsg);
+ if (cred->uid != 0) {
+ log_debug("sender uid="UID_FMT", message ignored", cred->uid);
+ return NULL;
+ }
+
+ if (memcmp(buf.raw, "libudev", 8) == 0) {
+ /* udev message needs proper version magic */
+ if (buf.nlh.magic != htobe32(UDEV_MONITOR_MAGIC)) {
+ log_debug("unrecognized message signature (%x != %x)",
+ buf.nlh.magic, htobe32(UDEV_MONITOR_MAGIC));
+ return NULL;
+ }
+ if (buf.nlh.properties_off+32 > (size_t)buflen) {
+ log_debug("message smaller than expected (%u > %zd)",
+ buf.nlh.properties_off+32, buflen);
+ return NULL;
+ }
+
+ bufpos = buf.nlh.properties_off;
+
+ /* devices received from udev are always initialized */
+ is_initialized = true;
+ } else {
+ /* kernel message with header */
+ bufpos = strlen(buf.raw) + 1;
+ if ((size_t)bufpos < sizeof("a@/d") || bufpos >= buflen) {
+ log_debug("invalid message length");
+ return NULL;
+ }
+
+ /* check message header */
+ if (strstr(buf.raw, "@/") == NULL) {
+ log_debug("unrecognized message header");
+ return NULL;
+ }
+ }
+
+ udev_device = udev_device_new_from_nulstr(udev_monitor->udev, &buf.raw[bufpos], buflen - bufpos);
+ if (!udev_device) {
+ log_debug("could not create device: %m");
+ return NULL;
+ }
+
+ if (is_initialized)
+ udev_device_set_is_initialized(udev_device);
+
+ /* 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, *val;
+ ssize_t blen, count;
+ struct udev_monitor_netlink_header nlh = {
+ .prefix = "libudev",
+ .magic = htobe32(UDEV_MONITOR_MAGIC),
+ .header_size = sizeof nlh,
+ };
+ struct iovec iov[2] = {
+ { .iov_base = &nlh, .iov_len = sizeof nlh },
+ };
+ struct msghdr smsg = {
+ .msg_iov = iov,
+ .msg_iovlen = 2,
+ };
+ struct udev_list_entry *list_entry;
+ uint64_t tag_bloom_bits;
+
+ blen = udev_device_get_properties_monitor_buf(udev_device, &buf);
+ if (blen < 32) {
+ log_debug("device buffer is too small to contain a valid device");
+ return -EINVAL;
+ }
+
+ /* fill in versioned header */
+ val = udev_device_get_subsystem(udev_device);
+ nlh.filter_subsystem_hash = htobe32(util_string_hash32(val));
+
+ val = udev_device_get_devtype(udev_device);
+ if (val != NULL)
+ nlh.filter_devtype_hash = htobe32(util_string_hash32(val));
+
+ /* 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 = htobe32(tag_bloom_bits >> 32);
+ nlh.filter_tag_bloom_lo = htobe32(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;
+
+ /*
+ * 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)
+ 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);
+ if (count < 0) {
+ if (!destination && errno == ECONNREFUSED) {
+ log_debug("passed device to netlink monitor %p", udev_monitor);
+ return 0;
+ } else
+ return -errno;
+ }
+
+ log_debug("passed %zi byte device to netlink monitor %p", count, udev_monitor);
+ return count;
+}
+
+/**
+ * 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.
+ */
+_public_ 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.
+ */
+_public_ 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.
+ */
+_public_ 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));
+}