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