src/udev/udev-ctrl.c

   1 /*
   2  * libudev - interface to udev device information
   3  *
   4  * Copyright (C) 2008 Kay Sievers <kay@vrfy.org>
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  */
  11
  12 #include <errno.h>
  13 #include <stdio.h>
  14 #include <stdlib.h>
  15 #include <stddef.h>
  16 #include <string.h>
  17 #include <unistd.h>
  18 #include <sys/types.h>
  19 #include <sys/poll.h>
  20 #include <sys/socket.h>
  21 #include <sys/un.h>
  22
  23 #include "udev.h"
  24
  25 /* wire protocol magic must match */
  26 #define UDEV_CTRL_MAGIC                                0xdead1dea
  27
  28 enum udev_ctrl_msg_type {
  29         UDEV_CTRL_UNKNOWN,
  30         UDEV_CTRL_SET_LOG_LEVEL,
  31         UDEV_CTRL_STOP_EXEC_QUEUE,
  32         UDEV_CTRL_START_EXEC_QUEUE,
  33         UDEV_CTRL_RELOAD,
  34         UDEV_CTRL_SET_ENV,
  35         UDEV_CTRL_SET_CHILDREN_MAX,
  36         UDEV_CTRL_PING,
  37         UDEV_CTRL_EXIT,
  38 };
  39
  40 struct udev_ctrl_msg_wire {
  41         char version[16];
  42         unsigned int magic;
  43         enum udev_ctrl_msg_type type;
  44         union {
  45                 int intval;
  46                 char buf[256];
  47         };
  48 };
  49
  50 struct udev_ctrl_msg {
  51         int refcount;
  52         struct udev_ctrl_connection *conn;
  53         struct udev_ctrl_msg_wire ctrl_msg_wire;
  54 };
  55
  56 struct udev_ctrl {
  57         int refcount;
  58         struct udev *udev;
  59         int sock;
  60         struct sockaddr_un saddr;
  61         socklen_t addrlen;
  62         bool bound;
  63         bool cleanup_socket;
  64         bool connected;
  65 };
  66
  67 struct udev_ctrl_connection {
  68         int refcount;
  69         struct udev_ctrl *uctrl;
  70         int sock;
  71 };
  72
  73 struct udev_ctrl *udev_ctrl_new_from_fd(struct udev *udev, int fd) {
  74         struct udev_ctrl *uctrl;
  75         const int on = 1;
  76         int r;
  77
  78         uctrl = new0(struct udev_ctrl, 1);
  79         if (uctrl == NULL)
  80                 return NULL;
  81         uctrl->refcount = 1;
  82         uctrl->udev = udev;
  83
  84         if (fd < 0) {
  85                 uctrl->sock = socket(AF_LOCAL, SOCK_SEQPACKET|SOCK_NONBLOCK|SOCK_CLOEXEC, 0);
  86                 if (uctrl->sock < 0) {
  87                         log_error("error getting socket: %m");
  88                         udev_ctrl_unref(uctrl);
  89                         return NULL;
  90                 }
  91         } else {
  92                 uctrl->bound = true;
  93                 uctrl->sock = fd;
  94         }
  95         r = setsockopt(uctrl->sock, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on));
  96         if (r < 0)
  97                 log_warning("could not set SO_PASSCRED: %m");
  98
  99         uctrl->saddr.sun_family = AF_LOCAL;
 100         strscpy(uctrl->saddr.sun_path, sizeof(uctrl->saddr.sun_path), "/run/udev/control");
 101         uctrl->addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(uctrl->saddr.sun_path);
 102         return uctrl;
 103 }
 104
 105 struct udev_ctrl *udev_ctrl_new(struct udev *udev) {
 106         return udev_ctrl_new_from_fd(udev, -1);
 107 }
 108
 109 int udev_ctrl_enable_receiving(struct udev_ctrl *uctrl) {
 110         int err;
 111
 112         if (!uctrl->bound) {
 113                 err = bind(uctrl->sock, (struct sockaddr *)&uctrl->saddr, uctrl->addrlen);
 114                 if (err < 0 && errno == EADDRINUSE) {
 115                         unlink(uctrl->saddr.sun_path);
 116                         err = bind(uctrl->sock, (struct sockaddr *)&uctrl->saddr, uctrl->addrlen);
 117                 }
 118
 119                 if (err < 0) {
 120                         err = -errno;
 121                         log_error("bind failed: %m");
 122                         return err;
 123                 }
 124
 125                 err = listen(uctrl->sock, 0);
 126                 if (err < 0) {
 127                         err = -errno;
 128                         log_error("listen failed: %m");
 129                         return err;
 130                 }
 131
 132                 uctrl->bound = true;
 133                 uctrl->cleanup_socket = true;
 134         }
 135         return 0;
 136 }
 137
 138 struct udev *udev_ctrl_get_udev(struct udev_ctrl *uctrl) {
 139         return uctrl->udev;
 140 }
 141
 142 static struct udev_ctrl *udev_ctrl_ref(struct udev_ctrl *uctrl) {
 143         if (uctrl == NULL)
 144                 return NULL;
 145         uctrl->refcount++;
 146         return uctrl;
 147 }
 148
 149 struct udev_ctrl *udev_ctrl_unref(struct udev_ctrl *uctrl) {
 150         if (uctrl == NULL)
 151                 return NULL;
 152         uctrl->refcount--;
 153         if (uctrl->refcount > 0)
 154                 return uctrl;
 155         if (uctrl->sock >= 0)
 156                 close(uctrl->sock);
 157         free(uctrl);
 158         return NULL;
 159 }
 160
 161 int udev_ctrl_cleanup(struct udev_ctrl *uctrl) {
 162         if (uctrl == NULL)
 163                 return 0;
 164         if (uctrl->cleanup_socket)
 165                 unlink(uctrl->saddr.sun_path);
 166         return 0;
 167 }
 168
 169 int udev_ctrl_get_fd(struct udev_ctrl *uctrl) {
 170         if (uctrl == NULL)
 171                 return -EINVAL;
 172         return uctrl->sock;
 173 }
 174
 175 struct udev_ctrl_connection *udev_ctrl_get_connection(struct udev_ctrl *uctrl) {
 176         struct udev_ctrl_connection *conn;
 177         struct ucred ucred = {};
 178         const int on = 1;
 179         int r;
 180
 181         conn = new(struct udev_ctrl_connection, 1);
 182         if (conn == NULL)
 183                 return NULL;
 184         conn->refcount = 1;
 185         conn->uctrl = uctrl;
 186
 187         conn->sock = accept4(uctrl->sock, NULL, NULL, SOCK_CLOEXEC|SOCK_NONBLOCK);
 188         if (conn->sock < 0) {
 189                 if (errno != EINTR)
 190                         log_error("unable to receive ctrl connection: %m");
 191                 goto err;
 192         }
 193
 194         /* check peer credential of connection */
 195         r = getpeercred(conn->sock, &ucred);
 196         if (r < 0) {
 197                 log_error_errno(-r, "unable to receive credentials of ctrl connection: %m");
 198                 goto err;
 199         }
 200         if (ucred.uid > 0) {
 201                 log_error("sender uid=%i, message ignored", ucred.uid);
 202                 goto err;
 203         }
 204
 205         /* enable receiving of the sender credentials in the messages */
 206         r = setsockopt(conn->sock, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on));
 207         if (r < 0)
 208                 log_warning("could not set SO_PASSCRED: %m");
 209
 210         udev_ctrl_ref(uctrl);
 211         return conn;
 212 err:
 213         if (conn->sock >= 0)
 214                 close(conn->sock);
 215         free(conn);
 216         return NULL;
 217 }
 218
 219 struct udev_ctrl_connection *udev_ctrl_connection_ref(struct udev_ctrl_connection *conn) {
 220         if (conn == NULL)
 221                 return NULL;
 222         conn->refcount++;
 223         return conn;
 224 }
 225
 226 struct udev_ctrl_connection *udev_ctrl_connection_unref(struct udev_ctrl_connection *conn) {
 227         if (conn == NULL)
 228                 return NULL;
 229         conn->refcount--;
 230         if (conn->refcount > 0)
 231                 return conn;
 232         if (conn->sock >= 0)
 233                 close(conn->sock);
 234         udev_ctrl_unref(conn->uctrl);
 235         free(conn);
 236         return NULL;
 237 }
 238
 239 static int ctrl_send(struct udev_ctrl *uctrl, enum udev_ctrl_msg_type type, int intval, const char *buf, int timeout) {
 240         struct udev_ctrl_msg_wire ctrl_msg_wire;
 241         int err = 0;
 242
 243         memzero(&ctrl_msg_wire, sizeof(struct udev_ctrl_msg_wire));
 244         strcpy(ctrl_msg_wire.version, "udev-" VERSION);
 245         ctrl_msg_wire.magic = UDEV_CTRL_MAGIC;
 246         ctrl_msg_wire.type = type;
 247
 248         if (buf != NULL)
 249                 strscpy(ctrl_msg_wire.buf, sizeof(ctrl_msg_wire.buf), buf);
 250         else
 251                 ctrl_msg_wire.intval = intval;
 252
 253         if (!uctrl->connected) {
 254                 if (connect(uctrl->sock, (struct sockaddr *)&uctrl->saddr, uctrl->addrlen) < 0) {
 255                         err = -errno;
 256                         goto out;
 257                 }
 258                 uctrl->connected = true;
 259         }
 260         if (send(uctrl->sock, &ctrl_msg_wire, sizeof(ctrl_msg_wire), 0) < 0) {
 261                 err = -errno;
 262                 goto out;
 263         }
 264
 265         /* wait for peer message handling or disconnect */
 266         for (;;) {
 267                 struct pollfd pfd[1];
 268                 int r;
 269
 270                 pfd[0].fd = uctrl->sock;
 271                 pfd[0].events = POLLIN;
 272                 r = poll(pfd, 1, timeout * MSEC_PER_SEC);
 273                 if (r  < 0) {
 274                         if (errno == EINTR)
 275                                 continue;
 276                         err = -errno;
 277                         break;
 278                 }
 279
 280                 if (r > 0 && pfd[0].revents & POLLERR) {
 281                         err = -EIO;
 282                         break;
 283                 }
 284
 285                 if (r == 0)
 286                         err = -ETIMEDOUT;
 287                 break;
 288         }
 289 out:
 290         return err;
 291 }
 292
 293 int udev_ctrl_send_set_log_level(struct udev_ctrl *uctrl, int priority, int timeout) {
 294         return ctrl_send(uctrl, UDEV_CTRL_SET_LOG_LEVEL, priority, NULL, timeout);
 295 }
 296
 297 int udev_ctrl_send_stop_exec_queue(struct udev_ctrl *uctrl, int timeout) {
 298         return ctrl_send(uctrl, UDEV_CTRL_STOP_EXEC_QUEUE, 0, NULL, timeout);
 299 }
 300
 301 int udev_ctrl_send_start_exec_queue(struct udev_ctrl *uctrl, int timeout) {
 302         return ctrl_send(uctrl, UDEV_CTRL_START_EXEC_QUEUE, 0, NULL, timeout);
 303 }
 304
 305 int udev_ctrl_send_reload(struct udev_ctrl *uctrl, int timeout) {
 306         return ctrl_send(uctrl, UDEV_CTRL_RELOAD, 0, NULL, timeout);
 307 }
 308
 309 int udev_ctrl_send_set_env(struct udev_ctrl *uctrl, const char *key, int timeout) {
 310         return ctrl_send(uctrl, UDEV_CTRL_SET_ENV, 0, key, timeout);
 311 }
 312
 313 int udev_ctrl_send_set_children_max(struct udev_ctrl *uctrl, int count, int timeout) {
 314         return ctrl_send(uctrl, UDEV_CTRL_SET_CHILDREN_MAX, count, NULL, timeout);
 315 }
 316
 317 int udev_ctrl_send_ping(struct udev_ctrl *uctrl, int timeout) {
 318         return ctrl_send(uctrl, UDEV_CTRL_PING, 0, NULL, timeout);
 319 }
 320
 321 int udev_ctrl_send_exit(struct udev_ctrl *uctrl, int timeout) {
 322         return ctrl_send(uctrl, UDEV_CTRL_EXIT, 0, NULL, timeout);
 323 }
 324
 325 struct udev_ctrl_msg *udev_ctrl_receive_msg(struct udev_ctrl_connection *conn) {
 326         struct udev_ctrl_msg *uctrl_msg;
 327         ssize_t size;
 328         struct cmsghdr *cmsg;
 329         struct iovec iov;
 330         char cred_msg[CMSG_SPACE(sizeof(struct ucred))];
 331         struct msghdr smsg = {
 332                 .msg_iov = &iov,
 333                 .msg_iovlen = 1,
 334                 .msg_control = cred_msg,
 335                 .msg_controllen = sizeof(cred_msg),
 336         };
 337         struct ucred *cred;
 338
 339         uctrl_msg = new0(struct udev_ctrl_msg, 1);
 340         if (uctrl_msg == NULL)
 341                 return NULL;
 342         uctrl_msg->refcount = 1;
 343         uctrl_msg->conn = conn;
 344         udev_ctrl_connection_ref(conn);
 345
 346         /* wait for the incoming message */
 347         for (;;) {
 348                 struct pollfd pfd[1];
 349                 int r;
 350
 351                 pfd[0].fd = conn->sock;
 352                 pfd[0].events = POLLIN;
 353
 354                 r = poll(pfd, 1, 10000);
 355                 if (r  < 0) {
 356                         if (errno == EINTR)
 357                                 continue;
 358                         goto err;
 359                 } else if (r == 0) {
 360                         log_error("timeout waiting for ctrl message");
 361                         goto err;
 362                 } else {
 363                         if (!(pfd[0].revents & POLLIN)) {
 364                                 log_error("ctrl connection error: %m");
 365                                 goto err;
 366                         }
 367                 }
 368
 369                 break;
 370         }
 371
 372         iov.iov_base = &uctrl_msg->ctrl_msg_wire;
 373         iov.iov_len = sizeof(struct udev_ctrl_msg_wire);
 374
 375         size = recvmsg(conn->sock, &smsg, 0);
 376         if (size <  0) {
 377                 log_error("unable to receive ctrl message: %m");
 378                 goto err;
 379         }
 380         cmsg = CMSG_FIRSTHDR(&smsg);
 381         cred = (struct ucred *) CMSG_DATA(cmsg);
 382
 383         if (cmsg == NULL || cmsg->cmsg_type != SCM_CREDENTIALS) {
 384                 log_error("no sender credentials received, message ignored");
 385                 goto err;
 386         }
 387
 388         if (cred->uid != 0) {
 389                 log_error("sender uid=%i, message ignored", cred->uid);
 390                 goto err;
 391         }
 392
 393         if (uctrl_msg->ctrl_msg_wire.magic != UDEV_CTRL_MAGIC) {
 394                 log_error("message magic 0x%08x doesn't match, ignore it", uctrl_msg->ctrl_msg_wire.magic);
 395                 goto err;
 396         }
 397
 398         return uctrl_msg;
 399 err:
 400         udev_ctrl_msg_unref(uctrl_msg);
 401         return NULL;
 402 }
 403
 404 struct udev_ctrl_msg *udev_ctrl_msg_unref(struct udev_ctrl_msg *ctrl_msg) {
 405         if (ctrl_msg == NULL)
 406                 return NULL;
 407         ctrl_msg->refcount--;
 408         if (ctrl_msg->refcount > 0)
 409                 return ctrl_msg;
 410         udev_ctrl_connection_unref(ctrl_msg->conn);
 411         free(ctrl_msg);
 412         return NULL;
 413 }
 414
 415 int udev_ctrl_get_set_log_level(struct udev_ctrl_msg *ctrl_msg) {
 416         if (ctrl_msg->ctrl_msg_wire.type == UDEV_CTRL_SET_LOG_LEVEL)
 417                 return ctrl_msg->ctrl_msg_wire.intval;
 418         return -1;
 419 }
 420
 421 int udev_ctrl_get_stop_exec_queue(struct udev_ctrl_msg *ctrl_msg) {
 422         if (ctrl_msg->ctrl_msg_wire.type == UDEV_CTRL_STOP_EXEC_QUEUE)
 423                 return 1;
 424         return -1;
 425 }
 426
 427 int udev_ctrl_get_start_exec_queue(struct udev_ctrl_msg *ctrl_msg) {
 428         if (ctrl_msg->ctrl_msg_wire.type == UDEV_CTRL_START_EXEC_QUEUE)
 429                 return 1;
 430         return -1;
 431 }
 432
 433 int udev_ctrl_get_reload(struct udev_ctrl_msg *ctrl_msg) {
 434         if (ctrl_msg->ctrl_msg_wire.type == UDEV_CTRL_RELOAD)
 435                 return 1;
 436         return -1;
 437 }
 438
 439 const char *udev_ctrl_get_set_env(struct udev_ctrl_msg *ctrl_msg) {
 440         if (ctrl_msg->ctrl_msg_wire.type == UDEV_CTRL_SET_ENV)
 441                 return ctrl_msg->ctrl_msg_wire.buf;
 442         return NULL;
 443 }
 444
 445 int udev_ctrl_get_set_children_max(struct udev_ctrl_msg *ctrl_msg) {
 446         if (ctrl_msg->ctrl_msg_wire.type == UDEV_CTRL_SET_CHILDREN_MAX)
 447                 return ctrl_msg->ctrl_msg_wire.intval;
 448         return -1;
 449 }
 450
 451 int udev_ctrl_get_ping(struct udev_ctrl_msg *ctrl_msg) {
 452         if (ctrl_msg->ctrl_msg_wire.type == UDEV_CTRL_PING)
 453                 return 1;
 454         return -1;
 455 }
 456
 457 int udev_ctrl_get_exit(struct udev_ctrl_msg *ctrl_msg) {
 458         if (ctrl_msg->ctrl_msg_wire.type == UDEV_CTRL_EXIT)
 459                 return 1;
 460         return -1;
 461 }