blockd.c

   1 #include <sys/types.h>
   2 #include <sys/stat.h>
   3 #include <sys/mount.h>
   4 #include <sys/wait.h>
   5
   6 #include <stdlib.h>
   7 #include <stdio.h>
   8 #include <unistd.h>
   9 #include <fcntl.h>
  10
  11 #include <errno.h>
  12
  13 #include <linux/limits.h>
  14 #include <linux/auto_fs4.h>
  15
  16 #include <libubox/uloop.h>
  17 #include <libubox/vlist.h>
  18 #include <libubox/ulog.h>
  19 #include <libubox/avl-cmp.h>
  20 #include <libubus.h>
  21
  22 #include "libfstools/libfstools.h"
  23
  24 #define AUTOFS_MOUNT_PATH       "/tmp/run/blockd/"
  25 #define AUTOFS_TIMEOUT          30
  26 #define AUTOFS_EXPIRE_TIMER     (5 * 1000)
  27
  28 struct hotplug_context {
  29         struct uloop_process process;
  30         void *priv;
  31 };
  32
  33 struct device {
  34         struct vlist_node node;
  35         struct blob_attr *msg;
  36         char *name;
  37         char *target;
  38         int autofs;
  39         int anon;
  40 };
  41
  42 static struct uloop_fd fd_autofs_read;
  43 static int fd_autofs_write = 0;
  44 static struct ubus_auto_conn conn;
  45 struct blob_buf bb = { 0 };
  46
  47 enum {
  48         MOUNT_UUID,
  49         MOUNT_LABEL,
  50         MOUNT_ENABLE,
  51         MOUNT_TARGET,
  52         MOUNT_DEVICE,
  53         MOUNT_OPTIONS,
  54         MOUNT_AUTOFS,
  55         MOUNT_ANON,
  56         MOUNT_REMOVE,
  57         __MOUNT_MAX
  58 };
  59
  60 static const struct blobmsg_policy mount_policy[__MOUNT_MAX] = {
  61         [MOUNT_UUID] = { .name = "uuid", .type = BLOBMSG_TYPE_STRING },
  62         [MOUNT_LABEL] = { .name = "label", .type = BLOBMSG_TYPE_STRING },
  63         [MOUNT_DEVICE] = { .name = "device", .type = BLOBMSG_TYPE_STRING },
  64         [MOUNT_TARGET] = { .name = "target", .type = BLOBMSG_TYPE_STRING },
  65         [MOUNT_OPTIONS] = { .name = "options", .type = BLOBMSG_TYPE_STRING },
  66         [MOUNT_ENABLE] = { .name = "enabled", .type = BLOBMSG_TYPE_INT32 },
  67         [MOUNT_AUTOFS] = { .name = "autofs", .type = BLOBMSG_TYPE_INT32 },
  68         [MOUNT_ANON] = { .name = "anon", .type = BLOBMSG_TYPE_INT32 },
  69         [MOUNT_REMOVE] = { .name = "remove", .type = BLOBMSG_TYPE_INT32 },
  70 };
  71
  72 static char*
  73 _find_mount_point(char *device)
  74 {
  75         char dev[32] = { 0 };
  76
  77         snprintf(dev, sizeof(dev), "/dev/%s", device);
  78
  79         return find_mount_point(dev, 0);
  80 }
  81
  82 static int
  83 block(char *cmd, char *action, char *device)
  84 {
  85         pid_t pid = fork();
  86         int ret = -1;
  87         int status;
  88         char *argv[5] = { 0 };
  89         int a = 0;
  90
  91         switch (pid) {
  92         case -1:
  93                 ULOG_ERR("failed to fork block process\n");
  94                 break;
  95
  96         case 0:
  97                 argv[a++] = "/sbin/block";
  98                 argv[a++] = cmd;
  99                 argv[a++] = action;
 100                 argv[a++] = device;
 101                 execvp(argv[0], argv);
 102                 ULOG_ERR("failed to spawn %s %s %s\n", *argv, action, device);
 103                 exit(EXIT_FAILURE);
 104
 105         default:
 106                 waitpid(pid, &status, 0);
 107                 ret = WEXITSTATUS(status);
 108                 if (ret)
 109                         ULOG_ERR("failed to run block. %s/%s\n", action, device);
 110                 break;
 111         }
 112
 113         return ret;
 114 }
 115
 116 static int hotplug_call_mount(const char *action, const char *devname,
 117                               uloop_process_handler cb, void *priv)
 118 {
 119         char * const argv[] = { "hotplug-call", "mount", NULL };
 120         struct hotplug_context *c = NULL;
 121         pid_t pid;
 122         int err;
 123
 124         if (cb) {
 125                 c = calloc(1, sizeof(*c));
 126                 if (!c)
 127                         return -ENOMEM;
 128         }
 129
 130         pid = fork();
 131         switch (pid) {
 132         case -1:
 133                 err = -errno;
 134                 ULOG_ERR("fork() failed\n");
 135                 return err;
 136         case 0:
 137                 uloop_end();
 138
 139                 setenv("ACTION", action, 1);
 140                 setenv("DEVICE", devname, 1);
 141
 142                 execv("/sbin/hotplug-call", argv);
 143                 exit(-1);
 144                 break;
 145         default:
 146                 if (c) {
 147                         c->process.pid = pid;
 148                         c->process.cb = cb;
 149                         c->priv = priv;
 150                         uloop_process_add(&c->process);
 151                 }
 152                 break;
 153         }
 154
 155         return 0;
 156 }
 157
 158 static void device_mount_remove_hotplug_cb(struct uloop_process *p, int stat)
 159 {
 160         struct hotplug_context *hctx = container_of(p, struct hotplug_context, process);
 161         struct device *device = hctx->priv;
 162         char *mp;
 163
 164         if (device->target)
 165                 unlink(device->target);
 166
 167         mp = _find_mount_point(device->name);
 168         if (mp) {
 169                 block("autofs", "remove", device->name);
 170                 free(mp);
 171         }
 172
 173         free(device);
 174         free(hctx);
 175 }
 176
 177 static void device_mount_remove(struct device *device)
 178 {
 179         hotplug_call_mount("remove", device->name,
 180                            device_mount_remove_hotplug_cb, device);
 181 }
 182
 183 static void device_mount_add(struct device *device)
 184 {
 185         struct stat st;
 186         char path[64];
 187
 188         snprintf(path, sizeof(path), "/tmp/run/blockd/%s", device->name);
 189         if (!lstat(device->target, &st)) {
 190                 if (S_ISLNK(st.st_mode))
 191                         unlink(device->target);
 192                 else if (S_ISDIR(st.st_mode))
 193                         rmdir(device->target);
 194         }
 195         if (symlink(path, device->target))
 196                 ULOG_ERR("failed to symlink %s->%s (%d) - %m\n", device->target, path, errno);
 197         else
 198                 hotplug_call_mount("add", device->name, NULL, NULL);
 199 }
 200
 201 static int
 202 device_move(struct device *device_o, struct device *device_n)
 203 {
 204         char path[64];
 205
 206         if (device_o->autofs != device_n->autofs)
 207                 return -1;
 208
 209         if (device_o->anon || device_n->anon)
 210                 return -1;
 211
 212         if (device_o->autofs) {
 213                 unlink(device_o->target);
 214                 snprintf(path, sizeof(path), "/tmp/run/blockd/%s", device_n->name);
 215                 if (symlink(path, device_n->target))
 216                         ULOG_ERR("failed to symlink %s->%s (%d) - %m\n", device_n->target, path, errno);
 217         } else {
 218                 mkdir(device_n->target, 0755);
 219                 if (mount(device_o->target, device_n->target, NULL, MS_MOVE, NULL))
 220                         rmdir(device_n->target);
 221                 else
 222                         rmdir(device_o->target);
 223         }
 224
 225         return 0;
 226 }
 227
 228 static void vlist_nop_update(struct vlist_tree *tree,
 229                              struct vlist_node *node_new,
 230                              struct vlist_node *node_old)
 231 {
 232 }
 233
 234 VLIST_TREE(devices, avl_strcmp, vlist_nop_update, false, false);
 235
 236 static int
 237 block_hotplug(struct ubus_context *ctx, struct ubus_object *obj,
 238               struct ubus_request_data *req, const char *method,
 239               struct blob_attr *msg)
 240 {
 241         struct blob_attr *data[__MOUNT_MAX];
 242         struct device *device;
 243         struct blob_attr *_msg;
 244         char *devname, *_name;
 245         char *target = NULL, *__target;
 246         char _target[32];
 247
 248         blobmsg_parse(mount_policy, __MOUNT_MAX, data, blob_data(msg), blob_len(msg));
 249
 250         if (!data[MOUNT_DEVICE])
 251                 return UBUS_STATUS_INVALID_ARGUMENT;
 252
 253         devname = blobmsg_get_string(data[MOUNT_DEVICE]);
 254
 255         if (data[MOUNT_TARGET]) {
 256                 target = blobmsg_get_string(data[MOUNT_TARGET]);
 257         } else {
 258                 snprintf(_target, sizeof(_target), "/mnt/%s",
 259                          blobmsg_get_string(data[MOUNT_DEVICE]));
 260                 target = _target;
 261         }
 262
 263         if (data[MOUNT_REMOVE])
 264                 device = vlist_find(&devices, devname, device, node);
 265         else
 266                 device = calloc_a(sizeof(*device), &_msg, blob_raw_len(msg),
 267                                   &_name, strlen(devname) + 1, &__target, strlen(target) + 1);
 268
 269         if (!device)
 270                 return UBUS_STATUS_UNKNOWN_ERROR;
 271
 272         if (data[MOUNT_REMOVE]) {
 273                 vlist_delete(&devices, &device->node);
 274
 275                 if (device->autofs)
 276                         device_mount_remove(device);
 277                 else
 278                         free(device);
 279         } else {
 280                 struct device *old = vlist_find(&devices, devname, device, node);
 281
 282                 device->autofs = data[MOUNT_AUTOFS] ? blobmsg_get_u32(data[MOUNT_AUTOFS]) : 0;
 283                 device->anon = data[MOUNT_ANON] ? blobmsg_get_u32(data[MOUNT_ANON]) : 0;
 284                 device->msg = _msg;
 285                 memcpy(_msg, msg, blob_raw_len(msg));
 286                 device->name = _name;
 287                 strcpy(_name, devname);
 288                 device->target = __target;
 289                 strcpy(__target, target);
 290
 291                 vlist_add(&devices, &device->node, device->name);
 292
 293                 if (old && !device_move(old, device)) {
 294                         if (device->autofs) {
 295                                 device_mount_remove(old);
 296                                 device_mount_add(device);
 297                         } else {
 298                                 block("mount", NULL, NULL);
 299                         }
 300                 } else if (device->autofs) {
 301                         device_mount_add(device);
 302                 }
 303         }
 304
 305         return 0;
 306 }
 307
 308 static int
 309 block_info(struct ubus_context *ctx, struct ubus_object *obj,
 310            struct ubus_request_data *req, const char *method,
 311            struct blob_attr *msg)
 312 {
 313         struct device *device;
 314         void *a;
 315
 316         blob_buf_init(&bb, 0);
 317         a = blobmsg_open_array(&bb, "devices");
 318         vlist_for_each_element(&devices, device, node) {
 319                 void *t = blobmsg_open_table(&bb, "");
 320                 struct blob_attr *v;
 321                 char *mp;
 322                 int rem;
 323
 324                 blob_for_each_attr(v, device->msg, rem)
 325                         blobmsg_add_blob(&bb, v);
 326
 327                 mp = _find_mount_point(device->name);
 328                 if (mp) {
 329                         blobmsg_add_string(&bb, "mount", mp);
 330                         free(mp);
 331                 } else if (device->autofs && device->target) {
 332                         blobmsg_add_string(&bb, "mount", device->target);
 333                 }
 334                 blobmsg_close_table(&bb, t);
 335         }
 336         blobmsg_close_array(&bb, a);
 337         ubus_send_reply(ctx, req, bb.head);
 338
 339         return 0;
 340 }
 341
 342 static const struct ubus_method block_methods[] = {
 343         UBUS_METHOD("hotplug", block_hotplug, mount_policy),
 344         UBUS_METHOD_NOARG("info", block_info),
 345 };
 346
 347 static struct ubus_object_type block_object_type =
 348         UBUS_OBJECT_TYPE("block", block_methods);
 349
 350 static struct ubus_object block_object = {
 351         .name = "block",
 352         .type = &block_object_type,
 353         .methods = block_methods,
 354         .n_methods = ARRAY_SIZE(block_methods),
 355 };
 356
 357 static void
 358 ubus_connect_handler(struct ubus_context *ctx)
 359 {
 360         int ret;
 361
 362         ret = ubus_add_object(ctx, &block_object);
 363         if (ret)
 364                 fprintf(stderr, "Failed to add object: %s\n", ubus_strerror(ret));
 365 }
 366
 367 static int autofs_umount(void)
 368 {
 369         umount2(AUTOFS_MOUNT_PATH, MNT_DETACH);
 370         return 0;
 371 }
 372
 373 static void autofs_read_handler(struct uloop_fd *u, unsigned int events)
 374 {
 375         union autofs_v5_packet_union pktu;
 376         const struct autofs_v5_packet *pkt;
 377         int cmd = AUTOFS_IOC_READY;
 378         struct stat st;
 379
 380         while (read(u->fd, &pktu, sizeof(pktu)) == -1) {
 381                 if (errno != EINTR)
 382                         return;
 383                 continue;
 384         }
 385
 386         if (pktu.hdr.type != autofs_ptype_missing_indirect) {
 387                 ULOG_ERR("unknown packet type %d\n", pktu.hdr.type);
 388                 return;
 389         }
 390
 391         pkt = &pktu.missing_indirect;
 392         ULOG_ERR("kernel is requesting a mount -> %s\n", pkt->name);
 393         if (lstat(pkt->name, &st) == -1)
 394                 if (block("autofs", "add", (char *)pkt->name))
 395                         cmd = AUTOFS_IOC_FAIL;
 396
 397         if (ioctl(fd_autofs_write, cmd, pkt->wait_queue_token) < 0)
 398                 ULOG_ERR("failed to report back to kernel\n");
 399 }
 400
 401 static void autofs_expire(struct uloop_timeout *t)
 402 {
 403         struct autofs_packet_expire pkt;
 404
 405         while (ioctl(fd_autofs_write, AUTOFS_IOC_EXPIRE, &pkt) == 0)
 406                 block("autofs", "remove", pkt.name);
 407
 408         uloop_timeout_set(t, AUTOFS_EXPIRE_TIMER);
 409 }
 410
 411 struct uloop_timeout autofs_expire_timer = {
 412         .cb = autofs_expire,
 413 };
 414
 415 static int autofs_mount(void)
 416 {
 417         int autofs_timeout = AUTOFS_TIMEOUT;
 418         int kproto_version;
 419         int pipefd[2];
 420         char source[64];
 421         char opts[64];
 422
 423         if (pipe(pipefd) < 0) {
 424                 ULOG_ERR("failed to get kernel pipe\n");
 425                 return -1;
 426         }
 427
 428         snprintf(source, sizeof(source), "mountd(pid%u)", getpid());
 429         snprintf(opts, sizeof(opts), "fd=%d,pgrp=%u,minproto=5,maxproto=5", pipefd[1], (unsigned) getpgrp());
 430         mkdir(AUTOFS_MOUNT_PATH, 0555);
 431         if (mount(source, AUTOFS_MOUNT_PATH, "autofs", 0, opts)) {
 432                 ULOG_ERR("unable to mount autofs on %s\n", AUTOFS_MOUNT_PATH);
 433                 close(pipefd[0]);
 434                 close(pipefd[1]);
 435                 return -1;
 436         }
 437         close(pipefd[1]);
 438         fd_autofs_read.fd = pipefd[0];
 439         fd_autofs_read.cb = autofs_read_handler;
 440         uloop_fd_add(&fd_autofs_read, ULOOP_READ);
 441
 442         fd_autofs_write = open(AUTOFS_MOUNT_PATH, O_RDONLY);
 443         if(fd_autofs_write < 0) {
 444                 autofs_umount();
 445                 ULOG_ERR("failed to open direcory\n");
 446                 return -1;
 447         }
 448
 449         ioctl(fd_autofs_write, AUTOFS_IOC_PROTOVER, &kproto_version);
 450         if (kproto_version != 5) {
 451                 ULOG_ERR("only kernel protocol version 5 is tested. You have %d.\n",
 452                         kproto_version);
 453                 exit(EXIT_FAILURE);
 454         }
 455         if (ioctl(fd_autofs_write, AUTOFS_IOC_SETTIMEOUT, &autofs_timeout))
 456                 ULOG_ERR("failed to set autofs timeout\n");
 457
 458         uloop_timeout_set(&autofs_expire_timer, AUTOFS_EXPIRE_TIMER);
 459
 460         fcntl(fd_autofs_write, F_SETFD, fcntl(fd_autofs_write, F_GETFD) | FD_CLOEXEC);
 461         fcntl(fd_autofs_read.fd, F_SETFD, fcntl(fd_autofs_read.fd, F_GETFD) | FD_CLOEXEC);
 462
 463         return 0;
 464 }
 465
 466 static void blockd_startup(struct uloop_timeout *t)
 467 {
 468         block("autofs", "start", NULL);
 469 }
 470
 471 struct uloop_timeout startup = {
 472         .cb = blockd_startup,
 473 };
 474
 475 int main(int argc, char **argv)
 476 {
 477         ulog_open(ULOG_SYSLOG | ULOG_STDIO, LOG_DAEMON, "blockd");
 478         uloop_init();
 479
 480         autofs_mount();
 481
 482         conn.cb = ubus_connect_handler;
 483         ubus_auto_connect(&conn);
 484
 485         uloop_timeout_set(&startup, 1000);
 486
 487         uloop_run();
 488         uloop_done();
 489
 490         autofs_umount();
 491
 492         vlist_flush_all(&devices);
 493
 494         return 0;
 495 }