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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-10 20:49:52 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-10 20:49:52 +0000
commit55944e5e40b1be2afc4855d8d2baf4b73d1876b5 (patch)
tree33f869f55a1b149e9b7c2b7e201867ca5dd52992 /src/libsystemd/sd-device/device-monitor.c
parentInitial commit. (diff)
downloadsystemd-55944e5e40b1be2afc4855d8d2baf4b73d1876b5.tar.xz
systemd-55944e5e40b1be2afc4855d8d2baf4b73d1876b5.zip
Adding upstream version 255.4.upstream/255.4
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/libsystemd/sd-device/device-monitor.c')
-rw-r--r--src/libsystemd/sd-device/device-monitor.c929
1 files changed, 929 insertions, 0 deletions
diff --git a/src/libsystemd/sd-device/device-monitor.c b/src/libsystemd/sd-device/device-monitor.c
new file mode 100644
index 0000000..bb4f9bd
--- /dev/null
+++ b/src/libsystemd/sd-device/device-monitor.c
@@ -0,0 +1,929 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <errno.h>
+#include <linux/filter.h>
+#include <linux/netlink.h>
+#include <linux/sockios.h>
+#include <sys/ioctl.h>
+#include <unistd.h>
+
+#include "sd-device.h"
+#include "sd-event.h"
+
+#include "MurmurHash2.h"
+#include "alloc-util.h"
+#include "device-filter.h"
+#include "device-monitor-private.h"
+#include "device-private.h"
+#include "device-util.h"
+#include "errno-util.h"
+#include "fd-util.h"
+#include "format-util.h"
+#include "hashmap.h"
+#include "iovec-util.h"
+#include "missing_socket.h"
+#include "mountpoint-util.h"
+#include "set.h"
+#include "socket-util.h"
+#include "stat-util.h"
+#include "string-util.h"
+#include "strv.h"
+#include "uid-range.h"
+
+#define log_monitor(m, format, ...) \
+ log_debug("sd-device-monitor(%s): " format, strna(m ? m->description : NULL), ##__VA_ARGS__)
+#define log_monitor_errno(m, r, format, ...) \
+ log_debug_errno(r, "sd-device-monitor(%s): " format, strna(m ? m->description : NULL), ##__VA_ARGS__)
+#define log_device_monitor(d, m, format, ...) \
+ log_device_debug(d, "sd-device-monitor(%s): " format, strna(m ? m->description : NULL), ##__VA_ARGS__)
+#define log_device_monitor_errno(d, m, r, format, ...) \
+ log_device_debug_errno(d, r, "sd-device-monitor(%s): " format, strna(m ? m->description : NULL), ##__VA_ARGS__)
+
+struct sd_device_monitor {
+ unsigned n_ref;
+
+ int sock;
+ union sockaddr_union snl;
+ union sockaddr_union snl_trusted_sender;
+ bool bound;
+
+ UidRange *mapped_userns_uid_range;
+
+ Hashmap *subsystem_filter;
+ Set *tag_filter;
+ Hashmap *match_sysattr_filter;
+ Hashmap *nomatch_sysattr_filter;
+ Set *match_parent_filter;
+ Set *nomatch_parent_filter;
+ bool filter_uptodate;
+
+ sd_event *event;
+ sd_event_source *event_source;
+ char *description;
+ sd_device_monitor_handler_t callback;
+ void *userdata;
+};
+
+#define UDEV_MONITOR_MAGIC 0xfeedcafe
+
+typedef struct 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 magic;
+ /* Total length of header structure known to the sender */
+ unsigned header_size;
+ /* Properties string buffer */
+ unsigned properties_off;
+ unsigned 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 filter_subsystem_hash;
+ unsigned filter_devtype_hash;
+ unsigned filter_tag_bloom_hi;
+ unsigned filter_tag_bloom_lo;
+} monitor_netlink_header;
+
+static int monitor_set_nl_address(sd_device_monitor *m) {
+ union sockaddr_union snl;
+ socklen_t addrlen;
+
+ assert(m);
+
+ /* Get the address the kernel has assigned us.
+ * It is usually, but not necessarily the pid. */
+ addrlen = sizeof(struct sockaddr_nl);
+ if (getsockname(m->sock, &snl.sa, &addrlen) < 0)
+ return -errno;
+
+ m->snl.nl.nl_pid = snl.nl.nl_pid;
+ return 0;
+}
+
+int device_monitor_allow_unicast_sender(sd_device_monitor *m, sd_device_monitor *sender) {
+ assert(m);
+ assert(sender);
+
+ m->snl_trusted_sender.nl.nl_pid = sender->snl.nl.nl_pid;
+ return 0;
+}
+
+_public_ int sd_device_monitor_set_receive_buffer_size(sd_device_monitor *m, size_t size) {
+ assert_return(m, -EINVAL);
+
+ return fd_set_rcvbuf(m->sock, size, false);
+}
+
+int device_monitor_disconnect(sd_device_monitor *m) {
+ assert(m);
+
+ m->sock = safe_close(m->sock);
+ return 0;
+}
+
+int device_monitor_get_fd(sd_device_monitor *m) {
+ assert(m);
+
+ return m->sock;
+}
+
+int device_monitor_new_full(sd_device_monitor **ret, MonitorNetlinkGroup group, int fd) {
+ _cleanup_(sd_device_monitor_unrefp) sd_device_monitor *m = NULL;
+ _cleanup_close_ int sock = -EBADF;
+ int r;
+
+ assert(group >= 0 && group < _MONITOR_NETLINK_GROUP_MAX);
+ assert_return(ret, -EINVAL);
+
+ if (group == MONITOR_GROUP_UDEV &&
+ access("/run/udev/control", F_OK) < 0 &&
+ dev_is_devtmpfs() <= 0) {
+
+ /*
+ * 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.
+ */
+
+ log_monitor(m, "The udev service seems not to be active, disabling the monitor.");
+ group = MONITOR_GROUP_NONE;
+ }
+
+ if (fd < 0) {
+ sock = socket(AF_NETLINK, SOCK_RAW|SOCK_CLOEXEC|SOCK_NONBLOCK, NETLINK_KOBJECT_UEVENT);
+ if (sock < 0)
+ return log_monitor_errno(m, errno, "Failed to create socket: %m");
+ }
+
+ m = new(sd_device_monitor, 1);
+ if (!m)
+ return -ENOMEM;
+
+ *m = (sd_device_monitor) {
+ .n_ref = 1,
+ .sock = fd >= 0 ? fd : TAKE_FD(sock),
+ .bound = fd >= 0,
+ .snl.nl.nl_family = AF_NETLINK,
+ .snl.nl.nl_groups = group,
+ };
+
+ if (fd >= 0) {
+ r = monitor_set_nl_address(m);
+ if (r < 0) {
+ log_monitor_errno(m, r, "Failed to set netlink address: %m");
+ goto fail;
+ }
+ }
+
+ if (DEBUG_LOGGING) {
+ _cleanup_close_ int netns = -EBADF;
+
+ /* So here's the thing: only AF_NETLINK sockets from the main network namespace will get
+ * hardware events. Let's check if ours is from there, and if not generate a debug message,
+ * since we cannot possibly work correctly otherwise. This is just a safety check to make
+ * things easier to debug. */
+
+ netns = ioctl(m->sock, SIOCGSKNS);
+ if (netns < 0)
+ log_monitor_errno(m, errno, "Unable to get network namespace of udev netlink socket, unable to determine if we are in host netns, ignoring: %m");
+ else {
+ struct stat a, b;
+
+ if (fstat(netns, &a) < 0) {
+ r = log_monitor_errno(m, errno, "Failed to stat netns of udev netlink socket: %m");
+ goto fail;
+ }
+
+ if (stat("/proc/1/ns/net", &b) < 0) {
+ if (ERRNO_IS_PRIVILEGE(errno))
+ /* If we can't access PID1's netns info due to permissions, it's fine, this is a
+ * safety check only after all. */
+ log_monitor_errno(m, errno, "No permission to stat PID1's netns, unable to determine if we are in host netns, ignoring: %m");
+ else
+ log_monitor_errno(m, errno, "Failed to stat PID1's netns, ignoring: %m");
+
+ } else if (!stat_inode_same(&a, &b))
+ log_monitor(m, "Netlink socket we listen on is not from host netns, we won't see device events.");
+ }
+ }
+
+ /* Let's bump the receive buffer size, but only if we are not called via socket activation, as in
+ * that case the service manager sets the receive buffer size for us, and the value in the .socket
+ * unit should take full effect. */
+ if (fd < 0) {
+ r = sd_device_monitor_set_receive_buffer_size(m, 128*1024*1024);
+ if (r < 0)
+ log_monitor_errno(m, r, "Failed to increase receive buffer size, ignoring: %m");
+ }
+
+ *ret = TAKE_PTR(m);
+ return 0;
+
+fail:
+ /* Let's unset the socket fd in the monitor object before we destroy it so that the fd passed in is
+ * not closed on failure. */
+ if (fd >= 0)
+ m->sock = -1;
+
+ return r;
+}
+
+_public_ int sd_device_monitor_new(sd_device_monitor **ret) {
+ return device_monitor_new_full(ret, MONITOR_GROUP_UDEV, -1);
+}
+
+_public_ int sd_device_monitor_stop(sd_device_monitor *m) {
+ assert_return(m, -EINVAL);
+
+ m->event_source = sd_event_source_unref(m->event_source);
+ (void) device_monitor_disconnect(m);
+
+ return 0;
+}
+
+static int device_monitor_event_handler(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
+ _cleanup_(sd_device_unrefp) sd_device *device = NULL;
+ _unused_ _cleanup_(log_context_unrefp) LogContext *c = NULL;
+ sd_device_monitor *m = ASSERT_PTR(userdata);
+
+ if (device_monitor_receive_device(m, &device) <= 0)
+ return 0;
+
+ if (log_context_enabled())
+ c = log_context_new_strv_consume(device_make_log_fields(device));
+
+ if (m->callback)
+ return m->callback(m, device, m->userdata);
+
+ return 0;
+}
+
+_public_ int sd_device_monitor_start(sd_device_monitor *m, sd_device_monitor_handler_t callback, void *userdata) {
+ int r;
+
+ assert_return(m, -EINVAL);
+
+ if (!m->event) {
+ r = sd_device_monitor_attach_event(m, NULL);
+ if (r < 0)
+ return r;
+ }
+
+ r = device_monitor_enable_receiving(m);
+ if (r < 0)
+ return r;
+
+ m->callback = callback;
+ m->userdata = userdata;
+
+ r = sd_event_add_io(m->event, &m->event_source, m->sock, EPOLLIN, device_monitor_event_handler, m);
+ if (r < 0)
+ return r;
+
+ (void) sd_event_source_set_description(m->event_source, m->description ?: "sd-device-monitor");
+
+ return 0;
+}
+
+_public_ int sd_device_monitor_detach_event(sd_device_monitor *m) {
+ assert_return(m, -EINVAL);
+
+ (void) sd_device_monitor_stop(m);
+ m->event = sd_event_unref(m->event);
+
+ return 0;
+}
+
+_public_ int sd_device_monitor_attach_event(sd_device_monitor *m, sd_event *event) {
+ int r;
+
+ assert_return(m, -EINVAL);
+ assert_return(!m->event, -EBUSY);
+
+ if (event)
+ m->event = sd_event_ref(event);
+ else {
+ r = sd_event_default(&m->event);
+ if (r < 0)
+ return r;
+ }
+
+ return 0;
+}
+
+_public_ sd_event *sd_device_monitor_get_event(sd_device_monitor *m) {
+ assert_return(m, NULL);
+
+ return m->event;
+}
+
+_public_ sd_event_source *sd_device_monitor_get_event_source(sd_device_monitor *m) {
+ assert_return(m, NULL);
+
+ return m->event_source;
+}
+
+_public_ int sd_device_monitor_set_description(sd_device_monitor *m, const char *description) {
+ int r;
+
+ assert_return(m, -EINVAL);
+
+ r = free_and_strdup(&m->description, description);
+ if (r <= 0)
+ return r;
+
+ if (m->event_source)
+ (void) sd_event_source_set_description(m->event_source, description);
+
+ return r;
+}
+
+_public_ int sd_device_monitor_get_description(sd_device_monitor *m, const char **ret) {
+ assert_return(m, -EINVAL);
+ assert_return(ret, -EINVAL);
+
+ *ret = m->description;
+ return 0;
+}
+
+int device_monitor_enable_receiving(sd_device_monitor *m) {
+ int r;
+
+ assert(m);
+
+ r = sd_device_monitor_filter_update(m);
+ if (r < 0)
+ return log_monitor_errno(m, r, "Failed to update filter: %m");
+
+ if (!m->bound) {
+ /* enable receiving of sender credentials */
+ r = setsockopt_int(m->sock, SOL_SOCKET, SO_PASSCRED, true);
+ if (r < 0)
+ return log_monitor_errno(m, r, "Failed to set socket option SO_PASSCRED: %m");
+
+ if (bind(m->sock, &m->snl.sa, sizeof(struct sockaddr_nl)) < 0)
+ return log_monitor_errno(m, errno, "Failed to bind monitoring socket: %m");
+
+ m->bound = true;
+
+ r = monitor_set_nl_address(m);
+ if (r < 0)
+ return log_monitor_errno(m, r, "Failed to set address: %m");
+ }
+
+ return 0;
+}
+
+static sd_device_monitor *device_monitor_free(sd_device_monitor *m) {
+ assert(m);
+
+ (void) sd_device_monitor_detach_event(m);
+
+ uid_range_free(m->mapped_userns_uid_range);
+ free(m->description);
+ hashmap_free(m->subsystem_filter);
+ set_free(m->tag_filter);
+ hashmap_free(m->match_sysattr_filter);
+ hashmap_free(m->nomatch_sysattr_filter);
+ set_free(m->match_parent_filter);
+ set_free(m->nomatch_parent_filter);
+
+ return mfree(m);
+}
+
+DEFINE_PUBLIC_TRIVIAL_REF_UNREF_FUNC(sd_device_monitor, sd_device_monitor, device_monitor_free);
+
+static int check_subsystem_filter(sd_device_monitor *m, sd_device *device) {
+ const char *s, *subsystem, *d, *devtype = NULL;
+ int r;
+
+ assert(m);
+ assert(device);
+
+ if (hashmap_isempty(m->subsystem_filter))
+ return true;
+
+ r = sd_device_get_subsystem(device, &subsystem);
+ if (r < 0)
+ return r;
+
+ r = sd_device_get_devtype(device, &devtype);
+ if (r < 0 && r != -ENOENT)
+ return r;
+
+ HASHMAP_FOREACH_KEY(d, s, m->subsystem_filter) {
+ if (!streq(s, subsystem))
+ continue;
+
+ if (!d || streq_ptr(d, devtype))
+ return true;
+ }
+
+ return false;
+}
+
+static bool check_tag_filter(sd_device_monitor *m, sd_device *device) {
+ const char *tag;
+
+ assert(m);
+ assert(device);
+
+ if (set_isempty(m->tag_filter))
+ return true;
+
+ SET_FOREACH(tag, m->tag_filter)
+ if (sd_device_has_tag(device, tag) > 0)
+ return true;
+
+ return false;
+}
+
+static int passes_filter(sd_device_monitor *m, sd_device *device) {
+ int r;
+
+ assert(m);
+ assert(device);
+
+ r = check_subsystem_filter(m, device);
+ if (r <= 0)
+ return r;
+
+ if (!check_tag_filter(m, device))
+ return false;
+
+ if (!device_match_sysattr(device, m->match_sysattr_filter, m->nomatch_sysattr_filter))
+ return false;
+
+ return device_match_parent(device, m->match_parent_filter, m->nomatch_parent_filter);
+}
+
+static bool check_sender_uid(sd_device_monitor *m, uid_t uid) {
+ int r;
+
+ assert(m);
+
+ /* Always trust messages from uid 0. */
+ if (uid == 0)
+ return true;
+
+ /* Trust messages sent by the same UID we are running. Currently, such situation happens only for
+ * unicast messages. */
+ if (uid == getuid() || uid == geteuid())
+ return true;
+
+ if (!m->mapped_userns_uid_range) {
+ r = uid_range_load_userns(&m->mapped_userns_uid_range, NULL);
+ if (r < 0)
+ log_monitor_errno(m, r, "Failed to load UID ranges mapped to the current user namespace, ignoring: %m");
+ }
+
+ /* Trust messages come from outside of the current user namespace. */
+ if (!uid_range_contains(m->mapped_userns_uid_range, uid))
+ return true;
+
+ /* Otherwise, refuse messages. */
+ return false;
+}
+
+int device_monitor_receive_device(sd_device_monitor *m, sd_device **ret) {
+ _cleanup_(sd_device_unrefp) sd_device *device = NULL;
+ _cleanup_free_ uint8_t *buf_alloc = NULL;
+ union {
+ monitor_netlink_header *nlh;
+ char *nulstr;
+ uint8_t *buf;
+ } message;
+ struct iovec iov;
+ CMSG_BUFFER_TYPE(CMSG_SPACE(sizeof(struct ucred))) control;
+ union sockaddr_union snl;
+ struct msghdr smsg = {
+ .msg_iov = &iov,
+ .msg_iovlen = 1,
+ .msg_control = &control,
+ .msg_controllen = sizeof(control),
+ .msg_name = &snl,
+ .msg_namelen = sizeof(snl),
+ };
+ struct ucred *cred;
+ size_t offset;
+ ssize_t n;
+ bool is_initialized = false;
+ int r;
+
+ assert(m);
+ assert(ret);
+
+ n = next_datagram_size_fd(m->sock);
+ if (n < 0) {
+ if (!ERRNO_IS_TRANSIENT(n))
+ log_monitor_errno(m, n, "Failed to get the received message size: %m");
+ return n;
+ }
+
+ if ((size_t) n < ALLOCA_MAX / sizeof(uint8_t) / 2)
+ message.buf = newa(uint8_t, n);
+ else {
+ buf_alloc = new(uint8_t, n);
+ if (!buf_alloc)
+ return log_oom_debug();
+
+ message.buf = buf_alloc;
+ }
+
+ iov = IOVEC_MAKE(message.buf, n);
+
+ n = recvmsg(m->sock, &smsg, 0);
+ if (n < 0) {
+ if (!ERRNO_IS_TRANSIENT(errno))
+ log_monitor_errno(m, errno, "Failed to receive message: %m");
+ return -errno;
+ }
+
+ if (smsg.msg_flags & MSG_TRUNC)
+ return log_monitor_errno(m, SYNTHETIC_ERRNO(EINVAL), "Received truncated message, ignoring message.");
+
+ if (n < 32)
+ return log_monitor_errno(m, SYNTHETIC_ERRNO(EINVAL), "Invalid message length (%zi), ignoring message.", n);
+
+ if (snl.nl.nl_groups == MONITOR_GROUP_NONE) {
+ /* unicast message, check if we trust the sender */
+ if (m->snl_trusted_sender.nl.nl_pid == 0 ||
+ snl.nl.nl_pid != m->snl_trusted_sender.nl.nl_pid)
+ return log_monitor_errno(m, SYNTHETIC_ERRNO(EAGAIN),
+ "Unicast netlink message ignored.");
+
+ } else if (snl.nl.nl_groups == MONITOR_GROUP_KERNEL) {
+ if (snl.nl.nl_pid > 0)
+ return log_monitor_errno(m, SYNTHETIC_ERRNO(EAGAIN),
+ "Multicast kernel netlink message from PID %"PRIu32" ignored.",
+ snl.nl.nl_pid);
+ }
+
+ cred = CMSG_FIND_DATA(&smsg, SOL_SOCKET, SCM_CREDENTIALS, struct ucred);
+ if (!cred)
+ return log_monitor_errno(m, SYNTHETIC_ERRNO(EAGAIN),
+ "No sender credentials received, ignoring message.");
+
+ if (!check_sender_uid(m, cred->uid))
+ return log_monitor_errno(m, SYNTHETIC_ERRNO(EAGAIN),
+ "Sender uid="UID_FMT", message ignored.", cred->uid);
+
+ if (!memchr(message.buf, 0, n))
+ return log_monitor_errno(m, SYNTHETIC_ERRNO(EAGAIN), "Received message without NUL, ignoring message.");
+
+ if (streq(message.nulstr, "libudev")) {
+ /* udev message needs proper version magic */
+ if (message.nlh->magic != htobe32(UDEV_MONITOR_MAGIC))
+ return log_monitor_errno(m, SYNTHETIC_ERRNO(EAGAIN),
+ "Invalid message signature (%x != %x).",
+ message.nlh->magic, htobe32(UDEV_MONITOR_MAGIC));
+
+ if (message.nlh->properties_off + 32 > (size_t) n)
+ return log_monitor_errno(m, SYNTHETIC_ERRNO(EAGAIN),
+ "Invalid offset for properties (%u > %zi).",
+ message.nlh->properties_off + 32, n);
+
+ offset = message.nlh->properties_off;
+
+ /* devices received from udev are always initialized */
+ is_initialized = true;
+
+ } else {
+ /* check kernel message header */
+ if (!strstr(message.nulstr, "@/"))
+ return log_monitor_errno(m, SYNTHETIC_ERRNO(EAGAIN), "Invalid message header.");
+
+ offset = strlen(message.nulstr) + 1;
+ if (offset >= (size_t) n)
+ return log_monitor_errno(m, SYNTHETIC_ERRNO(EAGAIN), "Invalid message length.");
+ }
+
+ r = device_new_from_nulstr(&device, message.nulstr + offset, n - offset);
+ if (r < 0)
+ return log_monitor_errno(m, r, "Failed to create device from received message: %m");
+
+ if (is_initialized)
+ device_set_is_initialized(device);
+
+ /* Skip device, if it does not pass the current filter */
+ r = passes_filter(m, device);
+ if (r < 0)
+ return log_device_monitor_errno(device, m, r, "Failed to check received device passing filter: %m");
+ if (r == 0)
+ log_device_monitor(device, m, "Received device does not pass filter, ignoring.");
+ else
+ *ret = TAKE_PTR(device);
+
+ return r;
+}
+
+static uint32_t string_hash32(const char *str) {
+ return MurmurHash2(str, strlen(str), 0);
+}
+
+/* Get a bunch of bit numbers out of the hash, and set the bits in our bit field */
+static uint64_t string_bloom64(const char *str) {
+ uint64_t bits = 0;
+ uint32_t hash = string_hash32(str);
+
+ bits |= UINT64_C(1) << (hash & 63);
+ bits |= UINT64_C(1) << ((hash >> 6) & 63);
+ bits |= UINT64_C(1) << ((hash >> 12) & 63);
+ bits |= UINT64_C(1) << ((hash >> 18) & 63);
+ return bits;
+}
+
+int device_monitor_send_device(
+ sd_device_monitor *m,
+ sd_device_monitor *destination,
+ sd_device *device) {
+
+ 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,
+ };
+ /* default destination for sending */
+ union sockaddr_union default_destination = {
+ .nl.nl_family = AF_NETLINK,
+ .nl.nl_groups = MONITOR_GROUP_UDEV,
+ };
+ uint64_t tag_bloom_bits;
+ const char *buf, *val;
+ ssize_t count;
+ size_t blen;
+ int r;
+
+ assert(m);
+ assert(device);
+
+ r = device_get_properties_nulstr(device, &buf, &blen);
+ if (r < 0)
+ return log_device_monitor_errno(device, m, r, "Failed to get device properties: %m");
+ if (blen < 32)
+ return log_device_monitor_errno(device, m, SYNTHETIC_ERRNO(EINVAL),
+ "Length of device property nulstr is too small to contain valid device information.");
+
+ /* fill in versioned header */
+ r = sd_device_get_subsystem(device, &val);
+ if (r < 0)
+ return log_device_monitor_errno(device, m, r, "Failed to get device subsystem: %m");
+ nlh.filter_subsystem_hash = htobe32(string_hash32(val));
+
+ if (sd_device_get_devtype(device, &val) >= 0)
+ nlh.filter_devtype_hash = htobe32(string_hash32(val));
+
+ /* add tag bloom filter */
+ tag_bloom_bits = 0;
+ FOREACH_DEVICE_TAG(device, tag)
+ tag_bloom_bits |= string_bloom64(tag);
+
+ 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] = IOVEC_MAKE((char*) buf, blen);
+
+ /*
+ * Use custom address for target, or the default one.
+ *
+ * If we send to a multicast group, we will get
+ * ECONNREFUSED, which is expected.
+ */
+ smsg.msg_name = destination ? &destination->snl : &default_destination;
+ smsg.msg_namelen = sizeof(struct sockaddr_nl);
+ count = sendmsg(m->sock, &smsg, 0);
+ if (count < 0) {
+ if (!destination && errno == ECONNREFUSED) {
+ log_device_monitor(device, m, "Passed to netlink monitor.");
+ return 0;
+ } else
+ return log_device_monitor_errno(device, m, errno, "Failed to send device to netlink monitor: %m");
+ }
+
+ log_device_monitor(device, m, "Passed %zi byte to netlink monitor.", count);
+ return count;
+}
+
+static void bpf_stmt(struct sock_filter *ins, unsigned *i,
+ unsigned short code, unsigned data) {
+ ins[(*i)++] = (struct sock_filter) {
+ .code = code,
+ .k = data,
+ };
+}
+
+static void bpf_jmp(struct sock_filter *ins, unsigned *i,
+ unsigned short code, unsigned data,
+ unsigned short jt, unsigned short jf) {
+ ins[(*i)++] = (struct sock_filter) {
+ .code = code,
+ .jt = jt,
+ .jf = jf,
+ .k = data,
+ };
+}
+
+_public_ int sd_device_monitor_filter_update(sd_device_monitor *m) {
+ struct sock_filter ins[512] = {};
+ struct sock_fprog filter;
+ const char *subsystem, *devtype, *tag;
+ unsigned i = 0;
+
+ assert_return(m, -EINVAL);
+
+ if (m->filter_uptodate)
+ return 0;
+
+ if (m->snl.nl.nl_groups == MONITOR_GROUP_KERNEL ||
+ (hashmap_isempty(m->subsystem_filter) &&
+ set_isempty(m->tag_filter))) {
+ m->filter_uptodate = true;
+ return 0;
+ }
+
+ /* load magic in A */
+ bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(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 (!set_isempty(m->tag_filter)) {
+ int tag_matches = set_size(m->tag_filter);
+
+ /* add all tags matches */
+ SET_FOREACH(tag, m->tag_filter) {
+ uint64_t tag_bloom_bits = string_bloom64(tag);
+ 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(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(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 (!hashmap_isempty(m->subsystem_filter)) {
+ HASHMAP_FOREACH_KEY(devtype, subsystem, m->subsystem_filter) {
+ uint32_t hash = string_hash32(subsystem);
+
+ /* load device subsystem value in A */
+ bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(monitor_netlink_header, filter_subsystem_hash));
+ if (!devtype) {
+ /* 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(monitor_netlink_header, filter_devtype_hash));
+ /* jump if value does not match */
+ hash = string_hash32(devtype);
+ 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 */
+ filter = (struct sock_fprog) {
+ .len = i,
+ .filter = ins,
+ };
+ if (setsockopt(m->sock, SOL_SOCKET, SO_ATTACH_FILTER, &filter, sizeof(filter)) < 0)
+ return -errno;
+
+ m->filter_uptodate = true;
+ return 0;
+}
+
+_public_ int sd_device_monitor_filter_add_match_subsystem_devtype(sd_device_monitor *m, const char *subsystem, const char *devtype) {
+ int r;
+
+ assert_return(m, -EINVAL);
+ assert_return(subsystem, -EINVAL);
+
+ /* Do not use string_has_ops_free_free or hashmap_put_strdup() here, as this may be called
+ * multiple times with the same subsystem but different devtypes. */
+ r = hashmap_put_strdup_full(&m->subsystem_filter, &trivial_hash_ops_free_free, subsystem, devtype);
+ if (r <= 0)
+ return r;
+
+ m->filter_uptodate = false;
+ return r;
+}
+
+_public_ int sd_device_monitor_filter_add_match_tag(sd_device_monitor *m, const char *tag) {
+ int r;
+
+ assert_return(m, -EINVAL);
+ assert_return(tag, -EINVAL);
+
+ r = set_put_strdup(&m->tag_filter, tag);
+ if (r <= 0)
+ return r;
+
+ m->filter_uptodate = false;
+ return r;
+}
+
+_public_ int sd_device_monitor_filter_add_match_sysattr(sd_device_monitor *m, const char *sysattr, const char *value, int match) {
+ Hashmap **hashmap;
+
+ assert_return(m, -EINVAL);
+ assert_return(sysattr, -EINVAL);
+
+ if (match)
+ hashmap = &m->match_sysattr_filter;
+ else
+ hashmap = &m->nomatch_sysattr_filter;
+
+ /* TODO: unset m->filter_uptodate on success when we support this filter on BPF. */
+ return update_match_strv(hashmap, sysattr, value, /* clear_on_null = */ true);
+}
+
+_public_ int sd_device_monitor_filter_add_match_parent(sd_device_monitor *m, sd_device *device, int match) {
+ const char *syspath;
+ Set **set;
+ int r;
+
+ assert_return(m, -EINVAL);
+ assert_return(device, -EINVAL);
+
+ r = sd_device_get_syspath(device, &syspath);
+ if (r < 0)
+ return r;
+
+ if (match)
+ set = &m->match_parent_filter;
+ else
+ set = &m->nomatch_parent_filter;
+
+ /* TODO: unset m->filter_uptodate on success when we support this filter on BPF. */
+ return set_put_strdup(set, syspath);
+}
+
+_public_ int sd_device_monitor_filter_remove(sd_device_monitor *m) {
+ static const struct sock_fprog filter = { 0, NULL };
+
+ assert_return(m, -EINVAL);
+
+ m->subsystem_filter = hashmap_free(m->subsystem_filter);
+ m->tag_filter = set_free(m->tag_filter);
+ m->match_sysattr_filter = hashmap_free(m->match_sysattr_filter);
+ m->nomatch_sysattr_filter = hashmap_free(m->nomatch_sysattr_filter);
+ m->match_parent_filter = set_free(m->match_parent_filter);
+ m->nomatch_parent_filter = set_free(m->nomatch_parent_filter);
+
+ if (setsockopt(m->sock, SOL_SOCKET, SO_DETACH_FILTER, &filter, sizeof(filter)) < 0)
+ return -errno;
+
+ m->filter_uptodate = true;
+ return 0;
+}