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         if (data[MOUNT_REMOVE]) {
 241                 vlist_delete(&devices, &device->node);
 242         } else {
 243                 if (data[MOUNT_AUTOFS])
 244                         device->autofs = blobmsg_get_u32(data[MOUNT_AUTOFS]);
 245                 else
 246                         device->autofs = 0;
 247                 if (data[MOUNT_ANON])
 248                         device->anon = blobmsg_get_u32(data[MOUNT_ANON]);
 249                 else
 250                         device->anon = 0;
 251                 device->msg = _msg;
 252                 memcpy(_msg, msg, blob_raw_len(msg));
 253                 device->name = _name;
 254                 strcpy(_name, devname);
 255                 device->target = __target;
 256                 strcpy(__target, target);
 257                 vlist_add(&devices, &device->node, device->name);
 258         }
 259
 260         return 0;
 261 }
 262
 263 static int
 264 block_info(struct ubus_context *ctx, struct ubus_object *obj,
 265            struct ubus_request_data *req, const char *method,
 266            struct blob_attr *msg)
 267 {
 268         struct device *device;
 269         void *a;
 270
 271         blob_buf_init(&bb, 0);
 272         a = blobmsg_open_array(&bb, "devices");
 273         vlist_for_each_element(&devices, device, node) {
 274                 void *t = blobmsg_open_table(&bb, "");
 275                 struct blob_attr *v;
 276                 char *mp;
 277                 int rem;
 278
 279                 blob_for_each_attr(v, device->msg, rem)
 280                         blobmsg_add_blob(&bb, v);
 281
 282                 mp = _find_mount_point(device->name);
 283                 if (mp) {
 284                         blobmsg_add_string(&bb, "mount", mp);
 285                         free(mp);
 286                 }
 287                 blobmsg_close_table(&bb, t);
 288         }
 289         blobmsg_close_array(&bb, a);
 290         ubus_send_reply(ctx, req, bb.head);
 291
 292         return 0;
 293 }
 294
 295 static const struct ubus_method block_methods[] = {
 296         UBUS_METHOD("hotplug", block_hotplug, mount_policy),
 297         UBUS_METHOD_NOARG("info", block_info),
 298 };
 299
 300 static struct ubus_object_type block_object_type =
 301         UBUS_OBJECT_TYPE("block", block_methods);
 302
 303 static struct ubus_object block_object = {
 304         .name = "block",
 305         .type = &block_object_type,
 306         .methods = block_methods,
 307         .n_methods = ARRAY_SIZE(block_methods),
 308 };
 309
 310 static void
 311 ubus_connect_handler(struct ubus_context *ctx)
 312 {
 313         int ret;
 314
 315         ret = ubus_add_object(ctx, &block_object);
 316         if (ret)
 317                 fprintf(stderr, "Failed to add object: %s\n", ubus_strerror(ret));
 318 }
 319
 320 static int autofs_umount(void)
 321 {
 322         umount2(AUTOFS_MOUNT_PATH, MNT_DETACH);
 323         return 0;
 324 }
 325
 326 static void autofs_read_handler(struct uloop_fd *u, unsigned int events)
 327 {
 328         union autofs_v5_packet_union pktu;
 329         const struct autofs_v5_packet *pkt;
 330         int cmd = AUTOFS_IOC_READY;
 331         struct stat st;
 332
 333         while (read(u->fd, &pktu, sizeof(pktu)) == -1) {
 334                 if (errno != EINTR)
 335                         return;
 336                 continue;
 337         }
 338
 339         if (pktu.hdr.type != autofs_ptype_missing_indirect) {
 340                 ULOG_ERR("unknown packet type %d\n", pktu.hdr.type);
 341                 return;
 342         }
 343
 344         pkt = &pktu.missing_indirect;
 345         ULOG_ERR("kernel is requesting a mount -> %s\n", pkt->name);
 346         if (lstat(pkt->name, &st) == -1)
 347                 if (block("autofs", "add", (char *)pkt->name))
 348                         cmd = AUTOFS_IOC_FAIL;
 349
 350         if (ioctl(fd_autofs_write, cmd, pkt->wait_queue_token) < 0)
 351                 ULOG_ERR("failed to report back to kernel\n");
 352 }
 353
 354 static void autofs_expire(struct uloop_timeout *t)
 355 {
 356         struct autofs_packet_expire pkt;
 357
 358         while (ioctl(fd_autofs_write, AUTOFS_IOC_EXPIRE, &pkt) == 0)
 359                 block("autofs", "remove", pkt.name);
 360
 361         uloop_timeout_set(t, AUTOFS_EXPIRE_TIMER);
 362 }
 363
 364 struct uloop_timeout autofs_expire_timer = {
 365         .cb = autofs_expire,
 366 };
 367
 368 static int autofs_mount(void)
 369 {
 370         int autofs_timeout = AUTOFS_TIMEOUT;
 371         int kproto_version;
 372         int pipefd[2];
 373         char source[64];
 374         char opts[64];
 375
 376         if (pipe(pipefd) < 0) {
 377                 ULOG_ERR("failed to get kernel pipe\n");
 378                 return -1;
 379         }
 380
 381         snprintf(source, sizeof(source), "mountd(pid%u)", getpid());
 382         snprintf(opts, sizeof(opts), "fd=%d,pgrp=%u,minproto=5,maxproto=5", pipefd[1], (unsigned) getpgrp());
 383         mkdir(AUTOFS_MOUNT_PATH, 0555);
 384         if (mount(source, AUTOFS_MOUNT_PATH, "autofs", 0, opts)) {
 385                 ULOG_ERR("unable to mount autofs on %s\n", AUTOFS_MOUNT_PATH);
 386                 close(pipefd[0]);
 387                 close(pipefd[1]);
 388                 return -1;
 389         }
 390         close(pipefd[1]);
 391         fd_autofs_read.fd = pipefd[0];
 392         fd_autofs_read.cb = autofs_read_handler;
 393         uloop_fd_add(&fd_autofs_read, ULOOP_READ);
 394
 395         fd_autofs_write = open(AUTOFS_MOUNT_PATH, O_RDONLY);
 396         if(fd_autofs_write < 0) {
 397                 autofs_umount();
 398                 ULOG_ERR("failed to open direcory\n");
 399                 return -1;
 400         }
 401
 402         ioctl(fd_autofs_write, AUTOFS_IOC_PROTOVER, &kproto_version);
 403         if (kproto_version != 5) {
 404                 ULOG_ERR("only kernel protocol version 5 is tested. You have %d.\n",
 405                         kproto_version);
 406                 exit(EXIT_FAILURE);
 407         }
 408         if (ioctl(fd_autofs_write, AUTOFS_IOC_SETTIMEOUT, &autofs_timeout))
 409                 ULOG_ERR("failed to set autofs timeout\n");
 410
 411         uloop_timeout_set(&autofs_expire_timer, AUTOFS_EXPIRE_TIMER);
 412
 413         fcntl(fd_autofs_write, F_SETFD, fcntl(fd_autofs_write, F_GETFD) | FD_CLOEXEC);
 414         fcntl(fd_autofs_read.fd, F_SETFD, fcntl(fd_autofs_read.fd, F_GETFD) | FD_CLOEXEC);
 415
 416         return 0;
 417 }
 418
 419 static void blockd_startup(struct uloop_timeout *t)
 420 {
 421         block("autofs", "start", NULL);
 422 }
 423
 424 struct uloop_timeout startup = {
 425         .cb = blockd_startup,
 426 };
 427
 428 int main(int argc, char **argv)
 429 {
 430         ulog_open(ULOG_SYSLOG | ULOG_STDIO, LOG_DAEMON, "blockd");
 431         uloop_init();
 432
 433         autofs_mount();
 434
 435         conn.cb = ubus_connect_handler;
 436         ubus_auto_connect(&conn);
 437
 438         uloop_timeout_set(&startup, 1000);
 439
 440         uloop_run();
 441         uloop_done();
 442
 443         autofs_umount();
 444
 445         vlist_flush_all(&devices);
 446
 447         return 0;
 448 }