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