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