libmultipath/uevent.c

   1 /*
   2  * uevent.c - trigger upon netlink uevents from the kernel
   3  *
   4  *      Only kernels from version 2.6.10* on provide the uevent netlink socket.
   5  *      Until the libc-kernel-headers are updated, you need to compile with:
   6  *
   7  *        gcc -I /lib/modules/`uname -r`/build/include -o uevent_listen uevent_listen.c
   8  *
   9  * Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org>
  10  *
  11  *      This program is free software; you can redistribute it and/or modify it
  12  *      under the terms of the GNU General Public License as published by the
  13  *      Free Software Foundation version 2 of the License.
  14  *
  15  *      This program is distributed in the hope that it will be useful, but
  16  *      WITHOUT ANY WARRANTY; without even the implied warranty of
  17  *      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  18  *      General Public License for more details.
  19  *
  20  *      You should have received a copy of the GNU General Public License along
  21  *      with this program.  If not, see <http://www.gnu.org/licenses/>.
  22  *
  23  */
  24
  25 #include <unistd.h>
  26 #include <stdio.h>
  27 #include <errno.h>
  28 #include <stdlib.h>
  29 #include <stddef.h>
  30 #include <string.h>
  31 #include <fcntl.h>
  32 #include <time.h>
  33 #include <sys/socket.h>
  34 #include <sys/user.h>
  35 #include <sys/un.h>
  36 #include <poll.h>
  37 #include <linux/types.h>
  38 #include <linux/netlink.h>
  39 #include <pthread.h>
  40 #include <signal.h>
  41 #include <limits.h>
  42 #include <sys/mman.h>
  43 #include <libudev.h>
  44 #include <errno.h>
  45
  46 #include "memory.h"
  47 #include "debug.h"
  48 #include "list.h"
  49 #include "uevent.h"
  50 #include "vector.h"
  51
  52 typedef int (uev_trigger)(struct uevent *, void * trigger_data);
  53
  54 pthread_t uevq_thr;
  55 LIST_HEAD(uevq);
  56 pthread_mutex_t uevq_lock = PTHREAD_MUTEX_INITIALIZER;
  57 pthread_mutex_t *uevq_lockp = &uevq_lock;
  58 pthread_cond_t uev_cond = PTHREAD_COND_INITIALIZER;
  59 pthread_cond_t *uev_condp = &uev_cond;
  60 uev_trigger *my_uev_trigger;
  61 void * my_trigger_data;
  62 int servicing_uev;
  63
  64 int is_uevent_busy(void)
  65 {
  66         int empty;
  67
  68         pthread_mutex_lock(uevq_lockp);
  69         empty = list_empty(&uevq);
  70         pthread_mutex_unlock(uevq_lockp);
  71         return (!empty || servicing_uev);
  72 }
  73
  74 struct uevent * alloc_uevent (void)
  75 {
  76         struct uevent *uev = MALLOC(sizeof(struct uevent));
  77
  78         if (uev)
  79                 INIT_LIST_HEAD(&uev->node);
  80
  81         return uev;
  82 }
  83
  84 void
  85 setup_thread_attr(pthread_attr_t *attr, size_t stacksize, int detached)
  86 {
  87         if (pthread_attr_init(attr)) {
  88                 fprintf(stderr, "can't initialize thread attr: %s\n",
  89                         strerror(errno));
  90                 exit(1);
  91         }
  92         if (stacksize < PTHREAD_STACK_MIN)
  93                 stacksize = PTHREAD_STACK_MIN;
  94
  95         if (pthread_attr_setstacksize(attr, stacksize)) {
  96                 fprintf(stderr, "can't set thread stack size to %lu: %s\n",
  97                         (unsigned long)stacksize, strerror(errno));
  98                 exit(1);
  99         }
 100         if (detached && pthread_attr_setdetachstate(attr,
 101                                                     PTHREAD_CREATE_DETACHED)) {
 102                 fprintf(stderr, "can't set thread to detached: %s\n",
 103                         strerror(errno));
 104                 exit(1);
 105         }
 106 }
 107
 108 /*
 109  * Called with uevq_lockp held
 110  */
 111 void
 112 service_uevq(struct list_head *tmpq)
 113 {
 114         struct uevent *uev, *tmp;
 115
 116         list_for_each_entry_safe(uev, tmp, tmpq, node) {
 117                 list_del_init(&uev->node);
 118
 119                 if (my_uev_trigger && my_uev_trigger(uev, my_trigger_data))
 120                         condlog(0, "uevent trigger error");
 121
 122                 if (uev->udev)
 123                         udev_device_unref(uev->udev);
 124                 FREE(uev);
 125         }
 126 }
 127
 128 static void uevq_stop(void *arg)
 129 {
 130         struct udev *udev = arg;
 131
 132         condlog(3, "Stopping uev queue");
 133         pthread_mutex_lock(uevq_lockp);
 134         my_uev_trigger = NULL;
 135         pthread_cond_signal(uev_condp);
 136         pthread_mutex_unlock(uevq_lockp);
 137         udev_unref(udev);
 138 }
 139
 140 void
 141 uevq_cleanup(struct list_head *tmpq)
 142 {
 143         struct uevent *uev, *tmp;
 144
 145         list_for_each_entry_safe(uev, tmp, tmpq, node) {
 146                 list_del_init(&uev->node);
 147                 FREE(uev);
 148         }
 149 }
 150
 151 /*
 152  * Service the uevent queue.
 153  */
 154 int uevent_dispatch(int (*uev_trigger)(struct uevent *, void * trigger_data),
 155                     void * trigger_data)
 156 {
 157         my_uev_trigger = uev_trigger;
 158         my_trigger_data = trigger_data;
 159
 160         mlockall(MCL_CURRENT | MCL_FUTURE);
 161
 162         while (1) {
 163                 LIST_HEAD(uevq_tmp);
 164
 165                 pthread_mutex_lock(uevq_lockp);
 166                 servicing_uev = 0;
 167                 /*
 168                  * Condition signals are unreliable,
 169                  * so make sure we only wait if we have to.
 170                  */
 171                 if (list_empty(&uevq)) {
 172                         pthread_cond_wait(uev_condp, uevq_lockp);
 173                 }
 174                 servicing_uev = 1;
 175                 list_splice_init(&uevq, &uevq_tmp);
 176                 pthread_mutex_unlock(uevq_lockp);
 177                 if (!my_uev_trigger)
 178                         break;
 179                 service_uevq(&uevq_tmp);
 180         }
 181         condlog(3, "Terminating uev service queue");
 182         uevq_cleanup(&uevq);
 183         return 0;
 184 }
 185
 186 struct uevent *uevent_from_buffer(char *buf, ssize_t buflen)
 187 {
 188         struct uevent *uev;
 189         char *buffer;
 190         size_t bufpos;
 191         int i;
 192         char *pos;
 193
 194         uev = alloc_uevent();
 195         if (!uev) {
 196                 condlog(1, "lost uevent, oom");
 197                 return NULL;
 198         }
 199
 200         if ((size_t)buflen > sizeof(buf)-1)
 201                 buflen = sizeof(buf)-1;
 202
 203         /*
 204          * Copy the shared receive buffer contents to buffer private
 205          * to this uevent so we can immediately reuse the shared buffer.
 206          */
 207         memcpy(uev->buffer, buf, HOTPLUG_BUFFER_SIZE + OBJECT_SIZE);
 208         buffer = uev->buffer;
 209         buffer[buflen] = '\0';
 210
 211         /* save start of payload */
 212         bufpos = strlen(buffer) + 1;
 213
 214         /* action string */
 215         uev->action = buffer;
 216         pos = strchr(buffer, '@');
 217         if (!pos) {
 218                 condlog(3, "bad action string '%s'", buffer);
 219                 FREE(uev);
 220                 return NULL;
 221         }
 222         pos[0] = '\0';
 223
 224         /* sysfs path */
 225         uev->devpath = &pos[1];
 226
 227         /* hotplug events have the environment attached - reconstruct envp[] */
 228         for (i = 0; (bufpos < (size_t)buflen) && (i < HOTPLUG_NUM_ENVP-1); i++) {
 229                 int keylen;
 230                 char *key;
 231
 232                 key = &buffer[bufpos];
 233                 keylen = strlen(key);
 234                 uev->envp[i] = key;
 235                 /* Filter out sequence number */
 236                 if (strncmp(key, "SEQNUM=", 7) == 0) {
 237                         char *eptr;
 238
 239                         uev->seqnum = strtoul(key + 7, &eptr, 10);
 240                         if (eptr == key + 7)
 241                                 uev->seqnum = -1;
 242                 }
 243                 bufpos += keylen + 1;
 244         }
 245         uev->envp[i] = NULL;
 246
 247         condlog(3, "uevent %ld '%s' from '%s'", uev->seqnum,
 248                 uev->action, uev->devpath);
 249         uev->kernel = strrchr(uev->devpath, '/');
 250         if (uev->kernel)
 251                 uev->kernel++;
 252
 253         /* print payload environment */
 254         for (i = 0; uev->envp[i] != NULL; i++)
 255                 condlog(5, "%s", uev->envp[i]);
 256
 257         return uev;
 258 }
 259
 260 int failback_listen(void)
 261 {
 262         int sock;
 263         struct sockaddr_nl snl;
 264         struct sockaddr_un sun;
 265         socklen_t addrlen;
 266         int retval;
 267         int rcvbufsz = 128*1024;
 268         int rcvsz = 0;
 269         int rcvszsz = sizeof(rcvsz);
 270         unsigned int *prcvszsz = (unsigned int *)&rcvszsz;
 271         const int feature_on = 1;
 272         /*
 273          * First check whether we have a udev socket
 274          */
 275         memset(&sun, 0x00, sizeof(struct sockaddr_un));
 276         sun.sun_family = AF_LOCAL;
 277         strcpy(&sun.sun_path[1], "/org/kernel/dm/multipath_event");
 278         addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(sun.sun_path+1) + 1;
 279
 280         sock = socket(AF_LOCAL, SOCK_DGRAM, 0);
 281         if (sock >= 0) {
 282
 283                 condlog(3, "reading events from udev socket.");
 284
 285                 /* the bind takes care of ensuring only one copy running */
 286                 retval = bind(sock, (struct sockaddr *) &sun, addrlen);
 287                 if (retval < 0) {
 288                         condlog(0, "bind failed, exit");
 289                         goto exit;
 290                 }
 291
 292                 /* enable receiving of the sender credentials */
 293                 retval = setsockopt(sock, SOL_SOCKET, SO_PASSCRED,
 294                                     &feature_on, sizeof(feature_on));
 295                 if (retval < 0) {
 296                         condlog(0, "failed to enable credential passing, exit");
 297                         goto exit;
 298                 }
 299
 300         } else {
 301                 /* Fallback to read kernel netlink events */
 302                 memset(&snl, 0x00, sizeof(struct sockaddr_nl));
 303                 snl.nl_family = AF_NETLINK;
 304                 snl.nl_pid = getpid();
 305                 snl.nl_groups = 0x01;
 306
 307                 sock = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_KOBJECT_UEVENT);
 308                 if (sock == -1) {
 309                         condlog(0, "error getting socket, exit");
 310                         return 1;
 311                 }
 312
 313                 condlog(3, "reading events from kernel.");
 314
 315                 /*
 316                  * try to avoid dropping uevents, even so, this is not a guarantee,
 317                  * but it does help to change the netlink uevent socket's
 318                  * receive buffer threshold from the default value of 106,496 to
 319                  * the maximum value of 262,142.
 320                  */
 321                 retval = setsockopt(sock, SOL_SOCKET, SO_RCVBUF, &rcvbufsz,
 322                                     sizeof(rcvbufsz));
 323
 324                 if (retval < 0) {
 325                         condlog(0, "error setting receive buffer size for socket, exit");
 326                         exit(1);
 327                 }
 328                 retval = getsockopt(sock, SOL_SOCKET, SO_RCVBUF, &rcvsz, prcvszsz);
 329                 if (retval < 0) {
 330                         condlog(0, "error setting receive buffer size for socket, exit");
 331                         exit(1);
 332                 }
 333                 condlog(3, "receive buffer size for socket is %u.", rcvsz);
 334
 335                 /* enable receiving of the sender credentials */
 336                 if (setsockopt(sock, SOL_SOCKET, SO_PASSCRED,
 337                                &feature_on, sizeof(feature_on)) < 0) {
 338                         condlog(0, "error on enabling credential passing for socket");
 339                         exit(1);
 340                 }
 341
 342                 retval = bind(sock, (struct sockaddr *) &snl,
 343                               sizeof(struct sockaddr_nl));
 344                 if (retval < 0) {
 345                         condlog(0, "bind failed, exit");
 346                         goto exit;
 347                 }
 348         }
 349
 350         while (1) {
 351                 size_t bufpos;
 352                 ssize_t buflen;
 353                 struct uevent *uev;
 354                 struct msghdr smsg;
 355                 struct iovec iov;
 356                 char cred_msg[CMSG_SPACE(sizeof(struct ucred))];
 357                 struct cmsghdr *cmsg;
 358                 struct ucred *cred;
 359                 static char buf[HOTPLUG_BUFFER_SIZE + OBJECT_SIZE];
 360
 361                 memset(buf, 0x00, sizeof(buf));
 362                 iov.iov_base = &buf;
 363                 iov.iov_len = sizeof(buf);
 364                 memset (&smsg, 0x00, sizeof(struct msghdr));
 365                 smsg.msg_iov = &iov;
 366                 smsg.msg_iovlen = 1;
 367                 smsg.msg_control = cred_msg;
 368                 smsg.msg_controllen = sizeof(cred_msg);
 369
 370                 buflen = recvmsg(sock, &smsg, 0);
 371                 if (buflen < 0) {
 372                         if (errno != EINTR)
 373                                 condlog(0, "error receiving message, errno %d", errno);
 374                         continue;
 375                 }
 376
 377                 cmsg = CMSG_FIRSTHDR(&smsg);
 378                 if (cmsg == NULL || cmsg->cmsg_type != SCM_CREDENTIALS) {
 379                         condlog(3, "no sender credentials received, message ignored");
 380                         continue;
 381                 }
 382
 383                 cred = (struct ucred *)CMSG_DATA(cmsg);
 384                 if (cred->uid != 0) {
 385                         condlog(3, "sender uid=%d, message ignored", cred->uid);
 386                         continue;
 387                 }
 388
 389                 /* skip header */
 390                 bufpos = strlen(buf) + 1;
 391                 if (bufpos < sizeof("a@/d") || bufpos >= sizeof(buf)) {
 392                         condlog(3, "invalid message length");
 393                         continue;
 394                 }
 395
 396                 /* check message header */
 397                 if (strstr(buf, "@/") == NULL) {
 398                         condlog(3, "unrecognized message header");
 399                         continue;
 400                 }
 401                 if ((size_t)buflen > sizeof(buf)-1) {
 402                         condlog(2, "buffer overflow for received uevent");
 403                         buflen = sizeof(buf)-1;
 404                 }
 405
 406                 uev = uevent_from_buffer(buf, buflen);
 407                 if (!uev)
 408                         continue;
 409                 /*
 410                  * Queue uevent and poke service pthread.
 411                  */
 412                 pthread_mutex_lock(uevq_lockp);
 413                 list_add_tail(&uev->node, &uevq);
 414                 pthread_cond_signal(uev_condp);
 415                 pthread_mutex_unlock(uevq_lockp);
 416         }
 417
 418 exit:
 419         close(sock);
 420         return 1;
 421 }
 422
 423 struct uevent *uevent_from_udev_device(struct udev_device *dev)
 424 {
 425         struct uevent *uev;
 426         int i = 0;
 427         char *pos, *end;
 428         struct udev_list_entry *list_entry;
 429
 430         uev = alloc_uevent();
 431         if (!uev) {
 432                 udev_device_unref(dev);
 433                 condlog(1, "lost uevent, oom");
 434                 return NULL;
 435         }
 436         pos = uev->buffer;
 437         end = pos + HOTPLUG_BUFFER_SIZE + OBJECT_SIZE - 1;
 438         udev_list_entry_foreach(list_entry, udev_device_get_properties_list_entry(dev)) {
 439                 const char *name, *value;
 440                 int bytes;
 441
 442                 name = udev_list_entry_get_name(list_entry);
 443                 if (!name)
 444                         name = "(null)";
 445                 value = udev_list_entry_get_value(list_entry);
 446                 if (!value)
 447                         value = "(null)";
 448                 bytes = snprintf(pos, end - pos, "%s=%s", name, value);
 449                 if (pos + bytes >= end) {
 450                         condlog(2, "buffer overflow for uevent");
 451                         break;
 452                 }
 453                 uev->envp[i] = pos;
 454                 pos += bytes;
 455                 *pos = '\0';
 456                 pos++;
 457                 if (strcmp(name, "DEVPATH") == 0)
 458                         uev->devpath = uev->envp[i] + 8;
 459                 if (strcmp(name, "ACTION") == 0)
 460                         uev->action = uev->envp[i] + 7;
 461                 i++;
 462                 if (i == HOTPLUG_NUM_ENVP - 1)
 463                         break;
 464         }
 465         uev->udev = dev;
 466         uev->envp[i] = NULL;
 467
 468         condlog(3, "uevent '%s' from '%s'", uev->action, uev->devpath);
 469         uev->kernel = strrchr(uev->devpath, '/');
 470         if (uev->kernel)
 471                 uev->kernel++;
 472
 473         /* print payload environment */
 474         for (i = 0; uev->envp[i] != NULL; i++)
 475                 condlog(5, "%s", uev->envp[i]);
 476         return uev;
 477 }
 478
 479 int uevent_listen(struct udev *udev)
 480 {
 481         int err = 2;
 482         struct udev_monitor *monitor = NULL;
 483         int fd, socket_flags, events;
 484         int need_failback = 1;
 485         int timeout = 30;
 486         LIST_HEAD(uevlisten_tmp);
 487
 488         /*
 489          * Queue uevents for service by dedicated thread so that the uevent
 490          * listening thread does not block on multipathd locks (vecs->lock)
 491          * thereby not getting to empty the socket's receive buffer queue
 492          * often enough.
 493          */
 494         if (!udev) {
 495                 condlog(1, "no udev context");
 496                 return 1;
 497         }
 498         udev_ref(udev);
 499         pthread_cleanup_push(uevq_stop, udev);
 500
 501         monitor = udev_monitor_new_from_netlink(udev, "udev");
 502         if (!monitor) {
 503                 condlog(2, "failed to create udev monitor");
 504                 goto out;
 505         }
 506 #ifdef LIBUDEV_API_RECVBUF
 507         if (udev_monitor_set_receive_buffer_size(monitor, 128 * 1024 * 1024))
 508                 condlog(2, "failed to increase buffer size");
 509 #endif
 510         fd = udev_monitor_get_fd(monitor);
 511         if (fd < 0) {
 512                 condlog(2, "failed to get monitor fd");
 513                 goto out;
 514         }
 515         socket_flags = fcntl(fd, F_GETFL);
 516         if (socket_flags < 0) {
 517                 condlog(2, "failed to get monitor socket flags : %s",
 518                         strerror(errno));
 519                 goto out;
 520         }
 521         if (fcntl(fd, F_SETFL, socket_flags & ~O_NONBLOCK) < 0) {
 522                 condlog(2, "failed to set monitor socket flags : %s",
 523                         strerror(errno));
 524                 goto out;
 525         }
 526         err = udev_monitor_filter_add_match_subsystem_devtype(monitor, "block",
 527                                                               NULL);
 528         if (err)
 529                 condlog(2, "failed to create filter : %s", strerror(-err));
 530         err = udev_monitor_enable_receiving(monitor);
 531         if (err) {
 532                 condlog(2, "failed to enable receiving : %s", strerror(-err));
 533                 goto out;
 534         }
 535
 536         events = 0;
 537         while (1) {
 538                 struct uevent *uev;
 539                 struct udev_device *dev;
 540                 struct pollfd ev_poll;
 541                 int poll_timeout;
 542                 int fdcount;
 543
 544                 memset(&ev_poll, 0, sizeof(struct pollfd));
 545                 ev_poll.fd = fd;
 546                 ev_poll.events = POLLIN;
 547                 poll_timeout = timeout * 1000;
 548                 errno = 0;
 549                 fdcount = poll(&ev_poll, 1, poll_timeout);
 550                 if (fdcount && ev_poll.revents & POLLIN) {
 551                         timeout = 0;
 552                         dev = udev_monitor_receive_device(monitor);
 553                         if (!dev) {
 554                                 condlog(0, "failed getting udev device");
 555                                 continue;
 556                         }
 557                         uev = uevent_from_udev_device(dev);
 558                         if (!uev)
 559                                 continue;
 560                         list_add_tail(&uev->node, &uevlisten_tmp);
 561                         events++;
 562                         continue;
 563                 }
 564                 if (fdcount < 0) {
 565                         if (errno == EINTR)
 566                                 continue;
 567
 568                         condlog(0, "error receiving "
 569                                 "uevent message: %m");
 570                         err = -errno;
 571                         break;
 572                 }
 573                 if (!list_empty(&uevlisten_tmp)) {
 574                         /*
 575                          * Queue uevents and poke service pthread.
 576                          */
 577                         condlog(3, "Forwarding %d uevents", events);
 578                         pthread_mutex_lock(uevq_lockp);
 579                         list_splice_tail_init(&uevlisten_tmp, &uevq);
 580                         pthread_cond_signal(uev_condp);
 581                         pthread_mutex_unlock(uevq_lockp);
 582                         events = 0;
 583                 }
 584                 timeout = 30;
 585         }
 586         need_failback = 0;
 587 out:
 588         if (monitor)
 589                 udev_monitor_unref(monitor);
 590         if (need_failback)
 591                 err = failback_listen();
 592         pthread_cleanup_pop(1);
 593         return err;
 594 }
 595
 596 extern int
 597 uevent_get_major(struct uevent *uev)
 598 {
 599         char *p, *q;
 600         int i, major = -1;
 601
 602         for (i = 0; uev->envp[i] != NULL; i++) {
 603                 if (!strncmp(uev->envp[i], "MAJOR", 5) && strlen(uev->envp[i]) > 6) {
 604                         p = uev->envp[i] + 6;
 605                         major = strtoul(p, &q, 10);
 606                         if (p == q) {
 607                                 condlog(2, "invalid major '%s'", p);
 608                                 major = -1;
 609                         }
 610                         break;
 611                 }
 612         }
 613         return major;
 614 }
 615
 616 extern int
 617 uevent_get_minor(struct uevent *uev)
 618 {
 619         char *p, *q;
 620         int i, minor = -1;
 621
 622         for (i = 0; uev->envp[i] != NULL; i++) {
 623                 if (!strncmp(uev->envp[i], "MINOR", 5) && strlen(uev->envp[i]) > 6) {
 624                         p = uev->envp[i] + 6;
 625                         minor = strtoul(p, &q, 10);
 626                         if (p == q) {
 627                                 condlog(2, "invalid minor '%s'", p);
 628                                 minor = -1;
 629                         }
 630                         break;
 631                 }
 632         }
 633         return minor;
 634 }
 635
 636 extern int
 637 uevent_get_disk_ro(struct uevent *uev)
 638 {
 639         char *p, *q;
 640         int i, ro = -1;
 641
 642         for (i = 0; uev->envp[i] != NULL; i++) {
 643                 if (!strncmp(uev->envp[i], "DISK_RO", 6) && strlen(uev->envp[i]) > 7) {
 644                         p = uev->envp[i] + 8;
 645                         ro = strtoul(p, &q, 10);
 646                         if (p == q) {
 647                                 condlog(2, "invalid read_only setting '%s'", p);
 648                                 ro = -1;
 649                         }
 650                         break;
 651                 }
 652         }
 653         return ro;
 654 }
 655
 656 extern char *
 657 uevent_get_dm_name(struct uevent *uev)
 658 {
 659         char *p = NULL;
 660         int i;
 661
 662         for (i = 0; uev->envp[i] != NULL; i++) {
 663                 if (!strncmp(uev->envp[i], "DM_NAME", 6) &&
 664                     strlen(uev->envp[i]) > 7) {
 665                         p = MALLOC(strlen(uev->envp[i] + 8) + 1);
 666                         strcpy(p, uev->envp[i] + 8);
 667                         break;
 668                 }
 669         }
 670         return p;
 671 }