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