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