src/libsystemd/sd-device/device-monitor.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2
   3 #include <errno.h>
   4 #include <linux/filter.h>
   5 #include <linux/netlink.h>
   6 #include <sys/socket.h>
   7
   8 #include "sd-device.h"
   9 #include "sd-event.h"
  10
  11 #include "MurmurHash2.h"
  12 #include "alloc-util.h"
  13 #include "device-monitor-private.h"
  14 #include "device-private.h"
  15 #include "device-util.h"
  16 #include "fd-util.h"
  17 #include "format-util.h"
  18 #include "hashmap.h"
  19 #include "io-util.h"
  20 #include "missing.h"
  21 #include "mountpoint-util.h"
  22 #include "set.h"
  23 #include "socket-util.h"
  24 #include "string-util.h"
  25 #include "strv.h"
  26
  27 struct sd_device_monitor {
  28         unsigned n_ref;
  29
  30         int sock;
  31         union sockaddr_union snl;
  32         union sockaddr_union snl_trusted_sender;
  33         bool bound;
  34
  35         Hashmap *subsystem_filter;
  36         Set *tag_filter;
  37         bool filter_uptodate;
  38
  39         sd_event *event;
  40         sd_event_source *event_source;
  41         sd_device_monitor_handler_t callback;
  42         void *userdata;
  43 };
  44
  45 #define UDEV_MONITOR_MAGIC                0xfeedcafe
  46
  47 typedef struct monitor_netlink_header {
  48         /* "libudev" prefix to distinguish libudev and kernel messages */
  49         char prefix[8];
  50         /* Magic to protect against daemon <-> Library message format mismatch
  51          * Used in the kernel from socket filter rules; needs to be stored in network order */
  52         unsigned magic;
  53         /* Total length of header structure known to the sender */
  54         unsigned header_size;
  55         /* Properties string buffer */
  56         unsigned properties_off;
  57         unsigned properties_len;
  58         /* Hashes of primary device properties strings, to let libudev subscribers
  59          * use in-kernel socket filters; values need to be stored in network order */
  60         unsigned filter_subsystem_hash;
  61         unsigned filter_devtype_hash;
  62         unsigned filter_tag_bloom_hi;
  63         unsigned filter_tag_bloom_lo;
  64 } monitor_netlink_header;
  65
  66 static int monitor_set_nl_address(sd_device_monitor *m) {
  67         union sockaddr_union snl;
  68         socklen_t addrlen;
  69
  70         assert(m);
  71
  72         /* Get the address the kernel has assigned us.
  73          * It is usually, but not necessarily the pid. */
  74         addrlen = sizeof(struct sockaddr_nl);
  75         if (getsockname(m->sock, &snl.sa, &addrlen) < 0)
  76                 return -errno;
  77
  78         m->snl.nl.nl_pid = snl.nl.nl_pid;
  79         return 0;
  80 }
  81
  82 int device_monitor_allow_unicast_sender(sd_device_monitor *m, sd_device_monitor *sender) {
  83         assert_return(m, -EINVAL);
  84         assert_return(sender, -EINVAL);
  85
  86         m->snl_trusted_sender.nl.nl_pid = sender->snl.nl.nl_pid;
  87         return 0;
  88 }
  89
  90 _public_ int sd_device_monitor_set_receive_buffer_size(sd_device_monitor *m, size_t size) {
  91         int r, n = (int) size;
  92
  93         assert_return(m, -EINVAL);
  94         assert_return((size_t) n == size, -EINVAL);
  95
  96         if (setsockopt_int(m->sock, SOL_SOCKET, SO_RCVBUFFORCE, n) < 0) {
  97                 r = setsockopt_int(m->sock, SOL_SOCKET, SO_RCVBUF, n);
  98                 if (r < 0)
  99                         return r;
 100         }
 101
 102         return 0;
 103 }
 104
 105 int device_monitor_disconnect(sd_device_monitor *m) {
 106         assert(m);
 107
 108         m->sock = safe_close(m->sock);
 109         return 0;
 110 }
 111
 112 int device_monitor_get_fd(sd_device_monitor *m) {
 113         assert_return(m, -EINVAL);
 114
 115         return m->sock;
 116 }
 117
 118 int device_monitor_new_full(sd_device_monitor **ret, MonitorNetlinkGroup group, int fd) {
 119         _cleanup_(sd_device_monitor_unrefp) sd_device_monitor *m = NULL;
 120         _cleanup_close_ int sock = -1;
 121         int r;
 122
 123         assert_return(ret, -EINVAL);
 124         assert_return(group >= 0 && group < _MONITOR_NETLINK_GROUP_MAX, -EINVAL);
 125
 126         if (group == MONITOR_GROUP_UDEV &&
 127             access("/run/udev/control", F_OK) < 0 &&
 128             dev_is_devtmpfs() <= 0) {
 129
 130                 /*
 131                  * We do not support subscribing to uevents if no instance of
 132                  * udev is running. Uevents would otherwise broadcast the
 133                  * processing data of the host into containers, which is not
 134                  * desired.
 135                  *
 136                  * Containers will currently not get any udev uevents, until
 137                  * a supporting infrastructure is available.
 138                  *
 139                  * We do not set a netlink multicast group here, so the socket
 140                  * will not receive any messages.
 141                  */
 142
 143                 log_debug("sd-device-monitor: The udev service seems not to be active, disabling the monitor");
 144                 group = MONITOR_GROUP_NONE;
 145         }
 146
 147         if (fd < 0) {
 148                 sock = socket(PF_NETLINK, SOCK_RAW|SOCK_CLOEXEC|SOCK_NONBLOCK, NETLINK_KOBJECT_UEVENT);
 149                 if (sock < 0)
 150                         return log_debug_errno(errno, "sd-device-monitor: Failed to create socket: %m");
 151         }
 152
 153         m = new(sd_device_monitor, 1);
 154         if (!m)
 155                 return -ENOMEM;
 156
 157         *m = (sd_device_monitor) {
 158                 .n_ref = 1,
 159                 .sock = fd >= 0 ? fd : TAKE_FD(sock),
 160                 .bound = fd >= 0,
 161                 .snl.nl.nl_family = AF_NETLINK,
 162                 .snl.nl.nl_groups = group,
 163         };
 164
 165         if (fd >= 0) {
 166                 r = monitor_set_nl_address(m);
 167                 if (r < 0)
 168                         return log_debug_errno(r, "sd-device-monitor: Failed to set netlink address: %m");
 169         }
 170
 171         *ret = TAKE_PTR(m);
 172         return 0;
 173 }
 174
 175 _public_ int sd_device_monitor_new(sd_device_monitor **ret) {
 176         return device_monitor_new_full(ret, MONITOR_GROUP_UDEV, -1);
 177 }
 178
 179 _public_ int sd_device_monitor_stop(sd_device_monitor *m) {
 180         assert_return(m, -EINVAL);
 181
 182         m->event_source = sd_event_source_unref(m->event_source);
 183         (void) device_monitor_disconnect(m);
 184
 185         return 0;
 186 }
 187
 188 static int device_monitor_event_handler(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
 189         _cleanup_(sd_device_unrefp) sd_device *device = NULL;
 190         sd_device_monitor *m = userdata;
 191
 192         assert(m);
 193
 194         if (device_monitor_receive_device(m, &device) <= 0)
 195                 return 0;
 196
 197         if (m->callback)
 198                 return m->callback(m, device, m->userdata);
 199
 200         return 0;
 201 }
 202
 203 _public_ int sd_device_monitor_start(sd_device_monitor *m, sd_device_monitor_handler_t callback, void *userdata) {
 204         int r;
 205
 206         assert_return(m, -EINVAL);
 207
 208         if (!m->event) {
 209                 r = sd_device_monitor_attach_event(m, NULL);
 210                 if (r < 0)
 211                         return r;
 212         }
 213
 214         r = device_monitor_enable_receiving(m);
 215         if (r < 0)
 216                 return r;
 217
 218         m->callback = callback;
 219         m->userdata = userdata;
 220
 221         r = sd_event_add_io(m->event, &m->event_source, m->sock, EPOLLIN, device_monitor_event_handler, m);
 222         if (r < 0)
 223                 return r;
 224
 225         (void) sd_event_source_set_description(m->event_source, "sd-device-monitor");
 226
 227         return 0;
 228 }
 229
 230 _public_ int sd_device_monitor_detach_event(sd_device_monitor *m) {
 231         assert_return(m, -EINVAL);
 232
 233         (void) sd_device_monitor_stop(m);
 234         m->event = sd_event_unref(m->event);
 235
 236         return 0;
 237 }
 238
 239 _public_ int sd_device_monitor_attach_event(sd_device_monitor *m, sd_event *event) {
 240         int r;
 241
 242         assert_return(m, -EINVAL);
 243         assert_return(!m->event, -EBUSY);
 244
 245         if (event)
 246                 m->event = sd_event_ref(event);
 247         else {
 248                 r = sd_event_default(&m->event);
 249                 if (r < 0)
 250                         return r;
 251         }
 252
 253         return 0;
 254 }
 255
 256 _public_ sd_event *sd_device_monitor_get_event(sd_device_monitor *m) {
 257         assert_return(m, NULL);
 258
 259         return m->event;
 260 }
 261
 262 _public_ sd_event_source *sd_device_monitor_get_event_source(sd_device_monitor *m) {
 263         assert_return(m, NULL);
 264
 265         return m->event_source;
 266 }
 267
 268 int device_monitor_enable_receiving(sd_device_monitor *m) {
 269         int r;
 270
 271         assert_return(m, -EINVAL);
 272
 273         r = sd_device_monitor_filter_update(m);
 274         if (r < 0)
 275                 return log_debug_errno(r, "sd-device-monitor: Failed to update filter: %m");
 276
 277         if (!m->bound) {
 278                 /* enable receiving of sender credentials */
 279                 r = setsockopt_int(m->sock, SOL_SOCKET, SO_PASSCRED, true);
 280                 if (r < 0)
 281                         return log_debug_errno(r, "sd-device-monitor: Failed to set socket option SO_PASSCRED: %m");
 282
 283                 if (bind(m->sock, &m->snl.sa, sizeof(struct sockaddr_nl)) < 0)
 284                         return log_debug_errno(errno, "sd-device-monitor: Failed to bind monitoring socket: %m");
 285
 286                 m->bound = true;
 287
 288                 r = monitor_set_nl_address(m);
 289                 if (r < 0)
 290                         return log_debug_errno(r, "sd-device-monitor: Failed to set address: %m");
 291         }
 292
 293         return 0;
 294 }
 295
 296 static sd_device_monitor *device_monitor_free(sd_device_monitor *m) {
 297         assert(m);
 298
 299         (void) sd_device_monitor_detach_event(m);
 300
 301         hashmap_free_free_free(m->subsystem_filter);
 302         set_free_free(m->tag_filter);
 303
 304         return mfree(m);
 305 }
 306
 307 DEFINE_PUBLIC_TRIVIAL_REF_UNREF_FUNC(sd_device_monitor, sd_device_monitor, device_monitor_free);
 308
 309 static int passes_filter(sd_device_monitor *m, sd_device *device) {
 310         const char *tag, *subsystem, *devtype, *s, *d = NULL;
 311         Iterator i;
 312         int r;
 313
 314         assert_return(m, -EINVAL);
 315         assert_return(device, -EINVAL);
 316
 317         if (hashmap_isempty(m->subsystem_filter))
 318                 goto tag;
 319
 320         r = sd_device_get_subsystem(device, &s);
 321         if (r < 0)
 322                 return r;
 323
 324         r = sd_device_get_devtype(device, &d);
 325         if (r < 0 && r != -ENOENT)
 326                 return r;
 327
 328         HASHMAP_FOREACH_KEY(devtype, subsystem, m->subsystem_filter, i) {
 329                 if (!streq(s, subsystem))
 330                         continue;
 331
 332                 if (!devtype)
 333                         goto tag;
 334
 335                 if (!d)
 336                         continue;
 337
 338                 if (streq(d, devtype))
 339                         goto tag;
 340         }
 341
 342         return 0;
 343
 344 tag:
 345         if (set_isempty(m->tag_filter))
 346                 return 1;
 347
 348         SET_FOREACH(tag, m->tag_filter, i)
 349                 if (sd_device_has_tag(device, tag) > 0)
 350                         return 1;
 351
 352         return 0;
 353 }
 354
 355 int device_monitor_receive_device(sd_device_monitor *m, sd_device **ret) {
 356         _cleanup_(sd_device_unrefp) sd_device *device = NULL;
 357         union {
 358                 monitor_netlink_header nlh;
 359                 char raw[8192];
 360         } buf;
 361         struct iovec iov = {
 362                 .iov_base = &buf,
 363                 .iov_len = sizeof(buf)
 364         };
 365         char cred_msg[CMSG_SPACE(sizeof(struct ucred))];
 366         union sockaddr_union snl;
 367         struct msghdr smsg = {
 368                 .msg_iov = &iov,
 369                 .msg_iovlen = 1,
 370                 .msg_control = cred_msg,
 371                 .msg_controllen = sizeof(cred_msg),
 372                 .msg_name = &snl,
 373                 .msg_namelen = sizeof(snl),
 374         };
 375         struct cmsghdr *cmsg;
 376         struct ucred *cred;
 377         ssize_t buflen, bufpos;
 378         bool is_initialized = false;
 379         int r;
 380
 381         assert(ret);
 382
 383         buflen = recvmsg(m->sock, &smsg, 0);
 384         if (buflen < 0) {
 385                 if (errno != EINTR)
 386                         log_debug_errno(errno, "sd-device-monitor: Failed to receive message: %m");
 387                 return -errno;
 388         }
 389
 390         if (buflen < 32 || (smsg.msg_flags & MSG_TRUNC))
 391                 return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
 392                                        "sd-device-monitor: Invalid message length.");
 393
 394         if (snl.nl.nl_groups == MONITOR_GROUP_NONE) {
 395                 /* unicast message, check if we trust the sender */
 396                 if (m->snl_trusted_sender.nl.nl_pid == 0 ||
 397                     snl.nl.nl_pid != m->snl_trusted_sender.nl.nl_pid)
 398                         return log_debug_errno(SYNTHETIC_ERRNO(EAGAIN),
 399                                                "sd-device-monitor: Unicast netlink message ignored.");
 400
 401         } else if (snl.nl.nl_groups == MONITOR_GROUP_KERNEL) {
 402                 if (snl.nl.nl_pid > 0)
 403                         return log_debug_errno(SYNTHETIC_ERRNO(EAGAIN),
 404                                                "sd-device-monitor: Multicast kernel netlink message from PID %"PRIu32" ignored.", snl.nl.nl_pid);
 405         }
 406
 407         cmsg = CMSG_FIRSTHDR(&smsg);
 408         if (!cmsg || cmsg->cmsg_type != SCM_CREDENTIALS)
 409                 return log_debug_errno(SYNTHETIC_ERRNO(EAGAIN),
 410                                        "sd-device-monitor: No sender credentials received, message ignored.");
 411
 412         cred = (struct ucred*) CMSG_DATA(cmsg);
 413         if (cred->uid != 0)
 414                 return log_debug_errno(SYNTHETIC_ERRNO(EAGAIN),
 415                                        "sd-device-monitor: Sender uid="UID_FMT", message ignored.", cred->uid);
 416
 417         if (streq(buf.raw, "libudev")) {
 418                 /* udev message needs proper version magic */
 419                 if (buf.nlh.magic != htobe32(UDEV_MONITOR_MAGIC))
 420                         return log_debug_errno(SYNTHETIC_ERRNO(EAGAIN),
 421                                                "sd-device-monitor: Invalid message signature (%x != %x)",
 422                                                buf.nlh.magic, htobe32(UDEV_MONITOR_MAGIC));
 423
 424                 if (buf.nlh.properties_off+32 > (size_t) buflen)
 425                         return log_debug_errno(SYNTHETIC_ERRNO(EAGAIN),
 426                                                "sd-device-monitor: Invalid message length (%u > %zd)",
 427                                                buf.nlh.properties_off+32, buflen);
 428
 429                 bufpos = buf.nlh.properties_off;
 430
 431                 /* devices received from udev are always initialized */
 432                 is_initialized = true;
 433
 434         } else {
 435                 /* kernel message with header */
 436                 bufpos = strlen(buf.raw) + 1;
 437                 if ((size_t) bufpos < sizeof("a@/d") || bufpos >= buflen)
 438                         return log_debug_errno(SYNTHETIC_ERRNO(EAGAIN),
 439                                                "sd-device-monitor: Invalid message length");
 440
 441                 /* check message header */
 442                 if (!strstr(buf.raw, "@/"))
 443                         return log_debug_errno(SYNTHETIC_ERRNO(EAGAIN),
 444                                                "sd-device-monitor: Invalid message header");
 445         }
 446
 447         r = device_new_from_nulstr(&device, (uint8_t*) &buf.raw[bufpos], buflen - bufpos);
 448         if (r < 0)
 449                 return log_debug_errno(r, "sd-device-monitor: Failed to create device from received message: %m");
 450
 451         if (is_initialized)
 452                 device_set_is_initialized(device);
 453
 454         /* Skip device, if it does not pass the current filter */
 455         r = passes_filter(m, device);
 456         if (r < 0)
 457                 return log_device_debug_errno(device, r, "sd-device-monitor: Failed to check received device passing filter: %m");
 458         if (r == 0)
 459                 log_device_debug(device, "sd-device-monitor: Received device does not pass filter, ignoring");
 460         else
 461                 *ret = TAKE_PTR(device);
 462
 463         return r;
 464 }
 465
 466 static uint32_t string_hash32(const char *str) {
 467         return MurmurHash2(str, strlen(str), 0);
 468 }
 469
 470 /* Get a bunch of bit numbers out of the hash, and set the bits in our bit field */
 471 static uint64_t string_bloom64(const char *str) {
 472         uint64_t bits = 0;
 473         uint32_t hash = string_hash32(str);
 474
 475         bits |= 1LLU << (hash & 63);
 476         bits |= 1LLU << ((hash >> 6) & 63);
 477         bits |= 1LLU << ((hash >> 12) & 63);
 478         bits |= 1LLU << ((hash >> 18) & 63);
 479         return bits;
 480 }
 481
 482 int device_monitor_send_device(
 483                 sd_device_monitor *m,
 484                 sd_device_monitor *destination,
 485                 sd_device *device) {
 486
 487         monitor_netlink_header nlh = {
 488                 .prefix = "libudev",
 489                 .magic = htobe32(UDEV_MONITOR_MAGIC),
 490                 .header_size = sizeof nlh,
 491         };
 492         struct iovec iov[2] = {
 493                 { .iov_base = &nlh, .iov_len = sizeof nlh },
 494         };
 495         struct msghdr smsg = {
 496                 .msg_iov = iov,
 497                 .msg_iovlen = 2,
 498         };
 499         /* default destination for sending */
 500         union sockaddr_union default_destination = {
 501                 .nl.nl_family = AF_NETLINK,
 502                 .nl.nl_groups = MONITOR_GROUP_UDEV,
 503         };
 504         uint64_t tag_bloom_bits;
 505         const char *buf, *val;
 506         ssize_t count;
 507         size_t blen;
 508         int r;
 509
 510         assert(m);
 511         assert(device);
 512
 513         r = device_get_properties_nulstr(device, (const uint8_t **) &buf, &blen);
 514         if (r < 0)
 515                 return log_device_debug_errno(device, r, "sd-device-monitor: Failed to get device properties: %m");
 516         if (blen < 32) {
 517                 log_device_debug(device, "sd-device-monitor: Length of device property nulstr is too small to contain valid device information");
 518                 return -EINVAL;
 519         }
 520
 521         /* fill in versioned header */
 522         r = sd_device_get_subsystem(device, &val);
 523         if (r < 0)
 524                 return log_device_debug_errno(device, r, "sd-device-monitor: Failed to get device subsystem: %m");
 525         nlh.filter_subsystem_hash = htobe32(string_hash32(val));
 526
 527         if (sd_device_get_devtype(device, &val) >= 0)
 528                 nlh.filter_devtype_hash = htobe32(string_hash32(val));
 529
 530         /* add tag bloom filter */
 531         tag_bloom_bits = 0;
 532         FOREACH_DEVICE_TAG(device, val)
 533                 tag_bloom_bits |= string_bloom64(val);
 534
 535         if (tag_bloom_bits > 0) {
 536                 nlh.filter_tag_bloom_hi = htobe32(tag_bloom_bits >> 32);
 537                 nlh.filter_tag_bloom_lo = htobe32(tag_bloom_bits & 0xffffffff);
 538         }
 539
 540         /* add properties list */
 541         nlh.properties_off = iov[0].iov_len;
 542         nlh.properties_len = blen;
 543         iov[1] = IOVEC_MAKE((char*) buf, blen);
 544
 545         /*
 546          * Use custom address for target, or the default one.
 547          *
 548          * If we send to a multicast group, we will get
 549          * ECONNREFUSED, which is expected.
 550          */
 551         smsg.msg_name = destination ? &destination->snl : &default_destination;
 552         smsg.msg_namelen = sizeof(struct sockaddr_nl);
 553         count = sendmsg(m->sock, &smsg, 0);
 554         if (count < 0) {
 555                 if (!destination && errno == ECONNREFUSED) {
 556                         log_device_debug(device, "sd-device-monitor: Passed to netlink monitor");
 557                         return 0;
 558                 } else
 559                         return log_device_debug_errno(device, errno, "sd-device-monitor: Failed to send device to netlink monitor: %m");
 560         }
 561
 562         log_device_debug(device, "sd-device-monitor: Passed %zi byte to netlink monitor", count);
 563         return count;
 564 }
 565
 566 static void bpf_stmt(struct sock_filter *ins, unsigned *i,
 567                      unsigned short code, unsigned data) {
 568         ins[(*i)++] = (struct sock_filter) {
 569                 .code = code,
 570                 .k = data,
 571         };
 572 }
 573
 574 static void bpf_jmp(struct sock_filter *ins, unsigned *i,
 575                     unsigned short code, unsigned data,
 576                     unsigned short jt, unsigned short jf) {
 577         ins[(*i)++] = (struct sock_filter) {
 578                 .code = code,
 579                 .jt = jt,
 580                 .jf = jf,
 581                 .k = data,
 582         };
 583 }
 584
 585 _public_ int sd_device_monitor_filter_update(sd_device_monitor *m) {
 586         struct sock_filter ins[512] = {};
 587         struct sock_fprog filter;
 588         const char *subsystem, *devtype, *tag;
 589         unsigned i = 0;
 590         Iterator it;
 591
 592         assert_return(m, -EINVAL);
 593
 594         if (m->filter_uptodate)
 595                 return 0;
 596
 597         if (hashmap_isempty(m->subsystem_filter) &&
 598             set_isempty(m->tag_filter)) {
 599                 m->filter_uptodate = true;
 600                 return 0;
 601         }
 602
 603         /* load magic in A */
 604         bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(monitor_netlink_header, magic));
 605         /* jump if magic matches */
 606         bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, UDEV_MONITOR_MAGIC, 1, 0);
 607         /* wrong magic, pass packet */
 608         bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff);
 609
 610         if (!set_isempty(m->tag_filter)) {
 611                 int tag_matches = set_size(m->tag_filter);
 612
 613                 /* add all tags matches */
 614                 SET_FOREACH(tag, m->tag_filter, it) {
 615                         uint64_t tag_bloom_bits = string_bloom64(tag);
 616                         uint32_t tag_bloom_hi = tag_bloom_bits >> 32;
 617                         uint32_t tag_bloom_lo = tag_bloom_bits & 0xffffffff;
 618
 619                         /* load device bloom bits in A */
 620                         bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(monitor_netlink_header, filter_tag_bloom_hi));
 621                         /* clear bits (tag bits & bloom bits) */
 622                         bpf_stmt(ins, &i, BPF_ALU|BPF_AND|BPF_K, tag_bloom_hi);
 623                         /* jump to next tag if it does not match */
 624                         bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, tag_bloom_hi, 0, 3);
 625
 626                         /* load device bloom bits in A */
 627                         bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(monitor_netlink_header, filter_tag_bloom_lo));
 628                         /* clear bits (tag bits & bloom bits) */
 629                         bpf_stmt(ins, &i, BPF_ALU|BPF_AND|BPF_K, tag_bloom_lo);
 630                         /* jump behind end of tag match block if tag matches */
 631                         tag_matches--;
 632                         bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, tag_bloom_lo, 1 + (tag_matches * 6), 0);
 633                 }
 634
 635                 /* nothing matched, drop packet */
 636                 bpf_stmt(ins, &i, BPF_RET|BPF_K, 0);
 637         }
 638
 639         /* add all subsystem matches */
 640         if (!hashmap_isempty(m->subsystem_filter)) {
 641                 HASHMAP_FOREACH_KEY(devtype, subsystem, m->subsystem_filter, it) {
 642                         uint32_t hash = string_hash32(subsystem);
 643
 644                         /* load device subsystem value in A */
 645                         bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(monitor_netlink_header, filter_subsystem_hash));
 646                         if (!devtype) {
 647                                 /* jump if subsystem does not match */
 648                                 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 1);
 649                         } else {
 650                                 /* jump if subsystem does not match */
 651                                 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 3);
 652                                 /* load device devtype value in A */
 653                                 bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(monitor_netlink_header, filter_devtype_hash));
 654                                 /* jump if value does not match */
 655                                 hash = string_hash32(devtype);
 656                                 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 1);
 657                         }
 658
 659                         /* matched, pass packet */
 660                         bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff);
 661
 662                         if (i+1 >= ELEMENTSOF(ins))
 663                                 return -E2BIG;
 664                 }
 665
 666                 /* nothing matched, drop packet */
 667                 bpf_stmt(ins, &i, BPF_RET|BPF_K, 0);
 668         }
 669
 670         /* matched, pass packet */
 671         bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff);
 672
 673         /* install filter */
 674         filter = (struct sock_fprog) {
 675                 .len = i,
 676                 .filter = ins,
 677         };
 678         if (setsockopt(m->sock, SOL_SOCKET, SO_ATTACH_FILTER, &filter, sizeof(filter)) < 0)
 679                 return -errno;
 680
 681         m->filter_uptodate = true;
 682         return 0;
 683 }
 684
 685 _public_ int sd_device_monitor_filter_add_match_subsystem_devtype(sd_device_monitor *m, const char *subsystem, const char *devtype) {
 686         _cleanup_free_ char *s = NULL, *d = NULL;
 687         int r;
 688
 689         assert_return(m, -EINVAL);
 690         assert_return(subsystem, -EINVAL);
 691
 692         s = strdup(subsystem);
 693         if (!s)
 694                 return -ENOMEM;
 695
 696         if (devtype) {
 697                 d = strdup(devtype);
 698                 if (!d)
 699                         return -ENOMEM;
 700         }
 701
 702         r = hashmap_ensure_allocated(&m->subsystem_filter, NULL);
 703         if (r < 0)
 704                 return r;
 705
 706         r = hashmap_put(m->subsystem_filter, s, d);
 707         if (r < 0)
 708                 return r;
 709
 710         s = d = NULL;
 711         m->filter_uptodate = false;
 712
 713         return 0;
 714 }
 715
 716 _public_ int sd_device_monitor_filter_add_match_tag(sd_device_monitor *m, const char *tag) {
 717         _cleanup_free_ char *t = NULL;
 718         int r;
 719
 720         assert_return(m, -EINVAL);
 721         assert_return(tag, -EINVAL);
 722
 723         t = strdup(tag);
 724         if (!t)
 725                 return -ENOMEM;
 726
 727         r = set_ensure_allocated(&m->tag_filter, &string_hash_ops);
 728         if (r < 0)
 729                 return r;
 730
 731         r = set_put(m->tag_filter, t);
 732         if (r == -EEXIST)
 733                 return 0;
 734         if (r < 0)
 735                 return r;
 736
 737         TAKE_PTR(t);
 738         m->filter_uptodate = false;
 739
 740         return 0;
 741 }
 742
 743 _public_ int sd_device_monitor_filter_remove(sd_device_monitor *m) {
 744         static const struct sock_fprog filter = { 0, NULL };
 745
 746         assert_return(m, -EINVAL);
 747
 748         m->subsystem_filter = hashmap_free_free_free(m->subsystem_filter);
 749         m->tag_filter = set_free_free(m->tag_filter);
 750
 751         if (setsockopt(m->sock, SOL_SOCKET, SO_DETACH_FILTER, &filter, sizeof(filter)) < 0)
 752                 return -errno;
 753
 754         m->filter_uptodate = true;
 755         return 0;
 756 }