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, write to the Free Software Foundation, Inc.,
  22  *      675 Mass Ave, Cambridge, MA 02139, USA.
  23  *
  24  */
  25
  26 #include <unistd.h>
  27 #include <stdio.h>
  28 #include <errno.h>
  29 #include <stdlib.h>
  30 #include <stddef.h>
  31 #include <string.h>
  32 #include <fcntl.h>
  33 #include <time.h>
  34 #include <sys/socket.h>
  35 #include <sys/user.h>
  36 #include <sys/un.h>
  37 #include <sys/poll.h>
  38 #include <linux/types.h>
  39 #include <linux/netlink.h>
  40 #include <pthread.h>
  41 #include <signal.h>
  42 #include <limits.h>
  43 #include <sys/mman.h>
  44 #include <libudev.h>
  45 #include <errno.h>
  46
  47 #include "memory.h"
  48 #include "debug.h"
  49 #include "list.h"
  50 #include "uevent.h"
  51 #include "vector.h"
  52
  53 typedef int (uev_trigger)(struct uevent *, void * trigger_data);
  54
  55 pthread_t uevq_thr;
  56 LIST_HEAD(uevq);
  57 pthread_mutex_t uevq_lock = PTHREAD_MUTEX_INITIALIZER;
  58 pthread_mutex_t *uevq_lockp = &uevq_lock;
  59 pthread_cond_t uev_cond = PTHREAD_COND_INITIALIZER;
  60 pthread_cond_t *uev_condp = &uev_cond;
  61 uev_trigger *my_uev_trigger;
  62 void * my_trigger_data;
  63 int servicing_uev;
  64
  65 int is_uevent_busy(void)
  66 {
  67         int empty;
  68
  69         pthread_mutex_lock(uevq_lockp);
  70         empty = list_empty(&uevq);
  71         pthread_mutex_unlock(uevq_lockp);
  72         return (!empty || servicing_uev);
  73 }
  74
  75 struct uevent * alloc_uevent (void)
  76 {
  77         struct uevent *uev = MALLOC(sizeof(struct uevent));
  78
  79         if (uev)
  80                 INIT_LIST_HEAD(&uev->node);
  81
  82         return uev;
  83 }
  84
  85 void
  86 setup_thread_attr(pthread_attr_t *attr, size_t stacksize, int detached)
  87 {
  88         if (pthread_attr_init(attr)) {
  89                 fprintf(stderr, "can't initialize thread attr: %s\n",
  90                         strerror(errno));
  91                 exit(1);
  92         }
  93         if (stacksize < PTHREAD_STACK_MIN)
  94                 stacksize = PTHREAD_STACK_MIN;
  95
  96         if (pthread_attr_setstacksize(attr, stacksize)) {
  97                 fprintf(stderr, "can't set thread stack size to %lu: %s\n",
  98                         (unsigned long)stacksize, strerror(errno));
  99                 exit(1);
 100         }
 101         if (detached && pthread_attr_setdetachstate(attr,
 102                                                     PTHREAD_CREATE_DETACHED)) {
 103                 fprintf(stderr, "can't set thread to detached: %s\n",
 104                         strerror(errno));
 105                 exit(1);
 106         }
 107 }
 108
 109 /*
 110  * Called with uevq_lockp held
 111  */
 112 void
 113 service_uevq(struct list_head *tmpq)
 114 {
 115         struct uevent *uev, *tmp;
 116
 117         list_for_each_entry_safe(uev, tmp, tmpq, node) {
 118                 list_del_init(&uev->node);
 119
 120                 if (my_uev_trigger && my_uev_trigger(uev, my_trigger_data))
 121                         condlog(0, "uevent trigger error");
 122
 123                 if (uev->udev)
 124                         udev_device_unref(uev->udev);
 125                 FREE(uev);
 126         }
 127 }
 128
 129 static void uevq_stop(void *arg)
 130 {
 131         struct udev *udev = arg;
 132
 133         condlog(3, "Stopping uev queue");
 134         pthread_mutex_lock(uevq_lockp);
 135         my_uev_trigger = NULL;
 136         pthread_cond_signal(uev_condp);
 137         pthread_mutex_unlock(uevq_lockp);
 138         udev_unref(udev);
 139 }
 140
 141 void
 142 uevq_cleanup(struct list_head *tmpq)
 143 {
 144         struct uevent *uev, *tmp;
 145
 146         list_for_each_entry_safe(uev, tmp, tmpq, node) {
 147                 list_del_init(&uev->node);
 148                 FREE(uev);
 149         }
 150 }
 151
 152 /*
 153  * Service the uevent queue.
 154  */
 155 int uevent_dispatch(int (*uev_trigger)(struct uevent *, void * trigger_data),
 156                     void * trigger_data)
 157 {
 158         my_uev_trigger = uev_trigger;
 159         my_trigger_data = trigger_data;
 160
 161         mlockall(MCL_CURRENT | MCL_FUTURE);
 162
 163         while (1) {
 164                 LIST_HEAD(uevq_tmp);
 165
 166                 pthread_mutex_lock(uevq_lockp);
 167                 servicing_uev = 0;
 168                 /*
 169                  * Condition signals are unreliable,
 170                  * so make sure we only wait if we have to.
 171                  */
 172                 if (list_empty(&uevq)) {
 173                         pthread_cond_wait(uev_condp, uevq_lockp);
 174                 }
 175                 servicing_uev = 1;
 176                 list_splice_init(&uevq, &uevq_tmp);
 177                 pthread_mutex_unlock(uevq_lockp);
 178                 if (!my_uev_trigger)
 179                         break;
 180                 service_uevq(&uevq_tmp);
 181         }
 182         condlog(3, "Terminating uev service queue");
 183         uevq_cleanup(&uevq);
 184         return 0;
 185 }
 186
 187 struct uevent *uevent_from_buffer(char *buf, ssize_t buflen)
 188 {
 189         struct uevent *uev;
 190         char *buffer;
 191         size_t bufpos;
 192         int i;
 193         char *pos;
 194
 195         uev = alloc_uevent();
 196         if (!uev) {
 197                 condlog(1, "lost uevent, oom");
 198                 return NULL;
 199         }
 200
 201         if ((size_t)buflen > sizeof(buf)-1)
 202                 buflen = sizeof(buf)-1;
 203
 204         /*
 205          * Copy the shared receive buffer contents to buffer private
 206          * to this uevent so we can immediately reuse the shared buffer.
 207          */
 208         memcpy(uev->buffer, buf, HOTPLUG_BUFFER_SIZE + OBJECT_SIZE);
 209         buffer = uev->buffer;
 210         buffer[buflen] = '\0';
 211
 212         /* save start of payload */
 213         bufpos = strlen(buffer) + 1;
 214
 215         /* action string */
 216         uev->action = buffer;
 217         pos = strchr(buffer, '@');
 218         if (!pos) {
 219                 condlog(3, "bad action string '%s'", buffer);
 220                 FREE(uev);
 221                 return NULL;
 222         }
 223         pos[0] = '\0';
 224
 225         /* sysfs path */
 226         uev->devpath = &pos[1];
 227
 228         /* hotplug events have the environment attached - reconstruct envp[] */
 229         for (i = 0; (bufpos < (size_t)buflen) && (i < HOTPLUG_NUM_ENVP-1); i++) {
 230                 int keylen;
 231                 char *key;
 232
 233                 key = &buffer[bufpos];
 234                 keylen = strlen(key);
 235                 uev->envp[i] = key;
 236                 /* Filter out sequence number */
 237                 if (strncmp(key, "SEQNUM=", 7) == 0) {
 238                         char *eptr;
 239
 240                         uev->seqnum = strtoul(key + 7, &eptr, 10);
 241                         if (eptr == key + 7)
 242                                 uev->seqnum = -1;
 243                 }
 244                 bufpos += keylen + 1;
 245         }
 246         uev->envp[i] = NULL;
 247
 248         condlog(3, "uevent %ld '%s' from '%s'", uev->seqnum,
 249                 uev->action, uev->devpath);
 250         uev->kernel = strrchr(uev->devpath, '/');
 251         if (uev->kernel)
 252                 uev->kernel++;
 253
 254         /* print payload environment */
 255         for (i = 0; uev->envp[i] != NULL; i++)
 256                 condlog(5, "%s", uev->envp[i]);
 257
 258         return uev;
 259 }
 260
 261 int failback_listen(void)
 262 {
 263         int sock;
 264         struct sockaddr_nl snl;
 265         struct sockaddr_un sun;
 266         socklen_t addrlen;
 267         int retval;
 268         int rcvbufsz = 128*1024;
 269         int rcvsz = 0;
 270         int rcvszsz = sizeof(rcvsz);
 271         unsigned int *prcvszsz = (unsigned int *)&rcvszsz;
 272         const int feature_on = 1;
 273         /*
 274          * First check whether we have a udev socket
 275          */
 276         memset(&sun, 0x00, sizeof(struct sockaddr_un));
 277         sun.sun_family = AF_LOCAL;
 278         strcpy(&sun.sun_path[1], "/org/kernel/dm/multipath_event");
 279         addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(sun.sun_path+1) + 1;
 280
 281         sock = socket(AF_LOCAL, SOCK_DGRAM, 0);
 282         if (sock >= 0) {
 283
 284                 condlog(3, "reading events from udev socket.");
 285
 286                 /* the bind takes care of ensuring only one copy running */
 287                 retval = bind(sock, (struct sockaddr *) &sun, addrlen);
 288                 if (retval < 0) {
 289                         condlog(0, "bind failed, exit");
 290                         goto exit;
 291                 }
 292
 293                 /* enable receiving of the sender credentials */
 294                 setsockopt(sock, SOL_SOCKET, SO_PASSCRED,
 295                            &feature_on, sizeof(feature_on));
 296
 297         } else {
 298                 /* Fallback to read kernel netlink events */
 299                 memset(&snl, 0x00, sizeof(struct sockaddr_nl));
 300                 snl.nl_family = AF_NETLINK;
 301                 snl.nl_pid = getpid();
 302                 snl.nl_groups = 0x01;
 303
 304                 sock = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_KOBJECT_UEVENT);
 305                 if (sock == -1) {
 306                         condlog(0, "error getting socket, exit");
 307                         return 1;
 308                 }
 309
 310                 condlog(3, "reading events from kernel.");
 311
 312                 /*
 313                  * try to avoid dropping uevents, even so, this is not a guarantee,
 314                  * but it does help to change the netlink uevent socket's
 315                  * receive buffer threshold from the default value of 106,496 to
 316                  * the maximum value of 262,142.
 317                  */
 318                 retval = setsockopt(sock, SOL_SOCKET, SO_RCVBUF, &rcvbufsz,
 319                                     sizeof(rcvbufsz));
 320
 321                 if (retval < 0) {
 322                         condlog(0, "error setting receive buffer size for socket, exit");
 323                         exit(1);
 324                 }
 325                 retval = getsockopt(sock, SOL_SOCKET, SO_RCVBUF, &rcvsz, prcvszsz);
 326                 if (retval < 0) {
 327                         condlog(0, "error setting receive buffer size for socket, exit");
 328                         exit(1);
 329                 }
 330                 condlog(3, "receive buffer size for socket is %u.", rcvsz);
 331
 332                 /* enable receiving of the sender credentials */
 333                 setsockopt(sock, SOL_SOCKET, SO_PASSCRED,
 334                            &feature_on, sizeof(feature_on));
 335
 336                 retval = bind(sock, (struct sockaddr *) &snl,
 337                               sizeof(struct sockaddr_nl));
 338                 if (retval < 0) {
 339                         condlog(0, "bind failed, exit");
 340                         goto exit;
 341                 }
 342         }
 343
 344         while (1) {
 345                 size_t bufpos;
 346                 ssize_t buflen;
 347                 struct uevent *uev;
 348                 struct msghdr smsg;
 349                 struct iovec iov;
 350                 char cred_msg[CMSG_SPACE(sizeof(struct ucred))];
 351                 struct cmsghdr *cmsg;
 352                 struct ucred *cred;
 353                 static char buf[HOTPLUG_BUFFER_SIZE + OBJECT_SIZE];
 354
 355                 memset(buf, 0x00, sizeof(buf));
 356                 iov.iov_base = &buf;
 357                 iov.iov_len = sizeof(buf);
 358                 memset (&smsg, 0x00, sizeof(struct msghdr));
 359                 smsg.msg_iov = &iov;
 360                 smsg.msg_iovlen = 1;
 361                 smsg.msg_control = cred_msg;
 362                 smsg.msg_controllen = sizeof(cred_msg);
 363
 364                 buflen = recvmsg(sock, &smsg, 0);
 365                 if (buflen < 0) {
 366                         if (errno != EINTR)
 367                                 condlog(0, "error receiving message, errno %d", errno);
 368                         continue;
 369                 }
 370
 371                 cmsg = CMSG_FIRSTHDR(&smsg);
 372                 if (cmsg == NULL || cmsg->cmsg_type != SCM_CREDENTIALS) {
 373                         condlog(3, "no sender credentials received, message ignored");
 374                         continue;
 375                 }
 376
 377                 cred = (struct ucred *)CMSG_DATA(cmsg);
 378                 if (cred->uid != 0) {
 379                         condlog(3, "sender uid=%d, message ignored", cred->uid);
 380                         continue;
 381                 }
 382
 383                 /* skip header */
 384                 bufpos = strlen(buf) + 1;
 385                 if (bufpos < sizeof("a@/d") || bufpos >= sizeof(buf)) {
 386                         condlog(3, "invalid message length");
 387                         continue;
 388                 }
 389
 390                 /* check message header */
 391                 if (strstr(buf, "@/") == NULL) {
 392                         condlog(3, "unrecognized message header");
 393                         continue;
 394                 }
 395                 if ((size_t)buflen > sizeof(buf)-1) {
 396                         condlog(2, "buffer overflow for received uevent");
 397                         buflen = sizeof(buf)-1;
 398                 }
 399
 400                 uev = uevent_from_buffer(buf, buflen);
 401                 if (!uev)
 402                         continue;
 403                 /*
 404                  * Queue uevent and poke service pthread.
 405                  */
 406                 pthread_mutex_lock(uevq_lockp);
 407                 list_add_tail(&uev->node, &uevq);
 408                 pthread_cond_signal(uev_condp);
 409                 pthread_mutex_unlock(uevq_lockp);
 410         }
 411
 412 exit:
 413         close(sock);
 414         return 1;
 415 }
 416
 417 struct uevent *uevent_from_udev_device(struct udev_device *dev)
 418 {
 419         struct uevent *uev;
 420         int i = 0;
 421         char *pos, *end;
 422         struct udev_list_entry *list_entry;
 423
 424         uev = alloc_uevent();
 425         if (!uev) {
 426                 udev_device_unref(dev);
 427                 condlog(1, "lost uevent, oom");
 428                 return NULL;
 429         }
 430         pos = uev->buffer;
 431         end = pos + HOTPLUG_BUFFER_SIZE + OBJECT_SIZE - 1;
 432         udev_list_entry_foreach(list_entry, udev_device_get_properties_list_entry(dev)) {
 433                 const char *name, *value;
 434                 int bytes;
 435
 436                 name = udev_list_entry_get_name(list_entry);
 437                 if (!name)
 438                         name = "(null)";
 439                 value = udev_list_entry_get_value(list_entry);
 440                 if (!value)
 441                         value = "(null)";
 442                 bytes = snprintf(pos, end - pos, "%s=%s", name, value);
 443                 if (pos + bytes >= end) {
 444                         condlog(2, "buffer overflow for uevent");
 445                         break;
 446                 }
 447                 uev->envp[i] = pos;
 448                 pos += bytes;
 449                 *pos = '\0';
 450                 pos++;
 451                 if (strcmp(name, "DEVPATH") == 0)
 452                         uev->devpath = uev->envp[i] + 8;
 453                 if (strcmp(name, "ACTION") == 0)
 454                         uev->action = uev->envp[i] + 7;
 455                 i++;
 456                 if (i == HOTPLUG_NUM_ENVP - 1)
 457                         break;
 458         }
 459         uev->udev = dev;
 460         uev->envp[i] = NULL;
 461
 462         condlog(3, "uevent '%s' from '%s'", uev->action, uev->devpath);
 463         uev->kernel = strrchr(uev->devpath, '/');
 464         if (uev->kernel)
 465                 uev->kernel++;
 466
 467         /* print payload environment */
 468         for (i = 0; uev->envp[i] != NULL; i++)
 469                 condlog(5, "%s", uev->envp[i]);
 470         return uev;
 471 }
 472
 473 int uevent_listen(struct udev *udev)
 474 {
 475         int err = 2;
 476         struct udev_monitor *monitor = NULL;
 477         int fd, fd_ep = -1, socket_flags, events;
 478         int need_failback = 1;
 479         int timeout = 30;
 480         sigset_t mask;
 481         LIST_HEAD(uevlisten_tmp);
 482
 483         /*
 484          * Queue uevents for service by dedicated thread so that the uevent
 485          * listening thread does not block on multipathd locks (vecs->lock)
 486          * thereby not getting to empty the socket's receive buffer queue
 487          * often enough.
 488          */
 489         if (!udev) {
 490                 condlog(1, "no udev context");
 491                 return 1;
 492         }
 493         udev_ref(udev);
 494         pthread_cleanup_push(uevq_stop, udev);
 495
 496         monitor = udev_monitor_new_from_netlink(udev, "udev");
 497         if (!monitor) {
 498                 condlog(2, "failed to create udev monitor");
 499                 goto out;
 500         }
 501 #ifdef LIBUDEV_API_RECVBUF
 502         if (udev_monitor_set_receive_buffer_size(monitor, 128 * 1024 * 1024))
 503                 condlog(2, "failed to increase buffer size");
 504 #endif
 505         fd = udev_monitor_get_fd(monitor);
 506         if (fd < 0) {
 507                 condlog(2, "failed to get monitor fd");
 508                 goto out;
 509         }
 510         socket_flags = fcntl(fd, F_GETFL);
 511         if (socket_flags < 0) {
 512                 condlog(2, "failed to get monitor socket flags : %s",
 513                         strerror(errno));
 514                 goto out;
 515         }
 516         if (fcntl(fd, F_SETFL, socket_flags & ~O_NONBLOCK) < 0) {
 517                 condlog(2, "failed to set monitor socket flags : %s",
 518                         strerror(errno));
 519                 goto out;
 520         }
 521         err = udev_monitor_filter_add_match_subsystem_devtype(monitor, "block",
 522                                                               NULL);
 523         if (err)
 524                 condlog(2, "failed to create filter : %s", strerror(-err));
 525         err = udev_monitor_enable_receiving(monitor);
 526         if (err) {
 527                 condlog(2, "failed to enable receiving : %s", strerror(-err));
 528                 goto out;
 529         }
 530
 531         pthread_sigmask(SIG_SETMASK, NULL, &mask);
 532         events = 0;
 533         while (1) {
 534                 struct uevent *uev;
 535                 struct udev_device *dev;
 536                 struct pollfd ev_poll;
 537                 struct timespec poll_timeout;
 538                 int fdcount;
 539
 540                 memset(&ev_poll, 0, sizeof(struct pollfd));
 541                 ev_poll.fd = fd;
 542                 ev_poll.events = POLLIN;
 543                 memset(&poll_timeout, 0, sizeof(struct timespec));
 544                 poll_timeout.tv_sec = timeout;
 545                 errno = 0;
 546                 fdcount = ppoll(&ev_poll, 1, &poll_timeout, &mask);
 547                 if (fdcount && ev_poll.revents & POLLIN) {
 548                         timeout = 0;
 549                         dev = udev_monitor_receive_device(monitor);
 550                         if (!dev) {
 551                                 condlog(0, "failed getting udev device");
 552                                 continue;
 553                         }
 554                         uev = uevent_from_udev_device(dev);
 555                         if (!uev)
 556                                 continue;
 557                         list_add_tail(&uev->node, &uevlisten_tmp);
 558                         events++;
 559                         continue;
 560                 }
 561                 if (fdcount < 0) {
 562                         if (errno == EINTR)
 563                                 continue;
 564
 565                         condlog(0, "error receiving "
 566                                 "uevent message: %m");
 567                         err = -errno;
 568                         break;
 569                 }
 570                 if (!list_empty(&uevlisten_tmp)) {
 571                         /*
 572                          * Queue uevents and poke service pthread.
 573                          */
 574                         condlog(3, "Forwarding %d uevents", events);
 575                         pthread_mutex_lock(uevq_lockp);
 576                         list_splice_tail_init(&uevlisten_tmp, &uevq);
 577                         pthread_cond_signal(uev_condp);
 578                         pthread_mutex_unlock(uevq_lockp);
 579                         events = 0;
 580                 }
 581                 timeout = 30;
 582         }
 583         need_failback = 0;
 584 out:
 585         if (fd_ep >= 0)
 586                 close(fd_ep);
 587         if (monitor)
 588                 udev_monitor_unref(monitor);
 589         if (need_failback)
 590                 err = failback_listen();
 591         pthread_cleanup_pop(1);
 592         return err;
 593 }
 594
 595 extern int
 596 uevent_get_major(struct uevent *uev)
 597 {
 598         char *p, *q;
 599         int i, major = -1;
 600
 601         for (i = 0; uev->envp[i] != NULL; i++) {
 602                 if (!strncmp(uev->envp[i], "MAJOR", 5) && strlen(uev->envp[i]) > 6) {
 603                         p = uev->envp[i] + 6;
 604                         major = strtoul(p, &q, 10);
 605                         if (p == q) {
 606                                 condlog(2, "invalid major '%s'", p);
 607                                 major = -1;
 608                         }
 609                         break;
 610                 }
 611         }
 612         return major;
 613 }
 614
 615 extern int
 616 uevent_get_minor(struct uevent *uev)
 617 {
 618         char *p, *q;
 619         int i, minor = -1;
 620
 621         for (i = 0; uev->envp[i] != NULL; i++) {
 622                 if (!strncmp(uev->envp[i], "MINOR", 5) && strlen(uev->envp[i]) > 6) {
 623                         p = uev->envp[i] + 6;
 624                         minor = strtoul(p, &q, 10);
 625                         if (p == q) {
 626                                 condlog(2, "invalid minor '%s'", p);
 627                                 minor = -1;
 628                         }
 629                         break;
 630                 }
 631         }
 632         return minor;
 633 }
 634
 635 extern int
 636 uevent_get_disk_ro(struct uevent *uev)
 637 {
 638         char *p, *q;
 639         int i, ro = -1;
 640
 641         for (i = 0; uev->envp[i] != NULL; i++) {
 642                 if (!strncmp(uev->envp[i], "DISK_RO", 6) && strlen(uev->envp[i]) > 7) {
 643                         p = uev->envp[i] + 8;
 644                         ro = strtoul(p, &q, 10);
 645                         if (p == q) {
 646                                 condlog(2, "invalid read_only setting '%s'", p);
 647                                 ro = -1;
 648                         }
 649                         break;
 650                 }
 651         }
 652         return ro;
 653 }
 654
 655 extern char *
 656 uevent_get_dm_name(struct uevent *uev)
 657 {
 658         char *p = NULL;
 659         int i;
 660
 661         for (i = 0; uev->envp[i] != NULL; i++) {
 662                 if (!strncmp(uev->envp[i], "DM_NAME", 6) &&
 663                     strlen(uev->envp[i]) > 7) {
 664                         p = MALLOC(strlen(uev->envp[i] + 8) + 1);
 665                         strcpy(p, uev->envp[i] + 8);
 666                         break;
 667                 }
 668         }
 669         return p;
 670 }