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Sources/fstools/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 }
458 

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