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