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