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