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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         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 }
449 

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