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 <stdlib.h>
  14 #include <stddef.h>
  15 #include <string.h>
  16 #include <unistd.h>
  17 #include <poll.h>
  18 #include <sys/socket.h>
  19 #include <sys/un.h>
  20
  21 #include "fd-util.h"
  22 #include "formats-util.h"
  23 #include "socket-util.h"
  24 #include "udev.h"
  25
  26 /* wire protocol magic must match */
  27 #define UDEV_CTRL_MAGIC                                0xdead1dea
  28
  29 enum udev_ctrl_msg_type {
  30         UDEV_CTRL_UNKNOWN,
  31         UDEV_CTRL_SET_LOG_LEVEL,
  32         UDEV_CTRL_STOP_EXEC_QUEUE,
  33         UDEV_CTRL_START_EXEC_QUEUE,
  34         UDEV_CTRL_RELOAD,
  35         UDEV_CTRL_SET_ENV,
  36         UDEV_CTRL_SET_CHILDREN_MAX,
  37         UDEV_CTRL_PING,
  38         UDEV_CTRL_EXIT,
  39 };
  40
  41 struct udev_ctrl_msg_wire {
  42         char version[16];
  43         unsigned int magic;
  44         enum udev_ctrl_msg_type type;
  45         union {
  46                 int intval;
  47                 char buf[256];
  48         };
  49 };
  50
  51 struct udev_ctrl_msg {
  52         int refcount;
  53         struct udev_ctrl_connection *conn;
  54         struct udev_ctrl_msg_wire ctrl_msg_wire;
  55 };
  56
  57 struct udev_ctrl {
  58         int refcount;
  59         struct udev *udev;
  60         int sock;
  61         union sockaddr_union saddr;
  62         socklen_t addrlen;
  63         bool bound;
  64         bool cleanup_socket;
  65         bool connected;
  66 };
  67
  68 struct udev_ctrl_connection {
  69         int refcount;
  70         struct udev_ctrl *uctrl;
  71         int sock;
  72 };
  73
  74 struct udev_ctrl *udev_ctrl_new_from_fd(struct udev *udev, int fd) {
  75         struct udev_ctrl *uctrl;
  76         const int on = 1;
  77         int r;
  78
  79         uctrl = new0(struct udev_ctrl, 1);
  80         if (uctrl == NULL)
  81                 return NULL;
  82         uctrl->refcount = 1;
  83         uctrl->udev = udev;
  84
  85         if (fd < 0) {
  86                 uctrl->sock = socket(AF_LOCAL, SOCK_SEQPACKET|SOCK_NONBLOCK|SOCK_CLOEXEC, 0);
  87                 if (uctrl->sock < 0) {
  88                         log_error_errno(errno, "error getting socket: %m");
  89                         udev_ctrl_unref(uctrl);
  90                         return NULL;
  91                 }
  92         } else {
  93                 uctrl->bound = true;
  94                 uctrl->sock = fd;
  95         }
  96
  97         /*
  98          * FIXME: remove it as soon as we can depend on this:
  99          *   http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=90c6bd34f884cd9cee21f1d152baf6c18bcac949
 100          */
 101         r = setsockopt(uctrl->sock, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on));
 102         if (r < 0)
 103                 log_warning_errno(errno, "could not set SO_PASSCRED: %m");
 104
 105         uctrl->saddr.un.sun_family = AF_LOCAL;
 106         strscpy(uctrl->saddr.un.sun_path, sizeof(uctrl->saddr.un.sun_path), "/run/udev/control");
 107         uctrl->addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(uctrl->saddr.un.sun_path);
 108         return uctrl;
 109 }
 110
 111 struct udev_ctrl *udev_ctrl_new(struct udev *udev) {
 112         return udev_ctrl_new_from_fd(udev, -1);
 113 }
 114
 115 int udev_ctrl_enable_receiving(struct udev_ctrl *uctrl) {
 116         int err;
 117
 118         if (!uctrl->bound) {
 119                 err = bind(uctrl->sock, &uctrl->saddr.sa, uctrl->addrlen);
 120                 if (err < 0 && errno == EADDRINUSE) {
 121                         unlink(uctrl->saddr.un.sun_path);
 122                         err = bind(uctrl->sock, &uctrl->saddr.sa, uctrl->addrlen);
 123                 }
 124
 125                 if (err < 0)
 126                         return log_error_errno(errno, "bind failed: %m");
 127
 128                 err = listen(uctrl->sock, 0);
 129                 if (err < 0)
 130                         return log_error_errno(errno, "listen failed: %m");
 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)
 144                 uctrl->refcount++;
 145
 146         return uctrl;
 147 }
 148
 149 struct udev_ctrl *udev_ctrl_unref(struct udev_ctrl *uctrl) {
 150         if (uctrl && -- uctrl->refcount == 0) {
 151                 if (uctrl->sock >= 0)
 152                         close(uctrl->sock);
 153                 free(uctrl);
 154         }
 155
 156         return NULL;
 157 }
 158
 159 int udev_ctrl_cleanup(struct udev_ctrl *uctrl) {
 160         if (uctrl == NULL)
 161                 return 0;
 162         if (uctrl->cleanup_socket)
 163                 unlink(uctrl->saddr.un.sun_path);
 164         return 0;
 165 }
 166
 167 int udev_ctrl_get_fd(struct udev_ctrl *uctrl) {
 168         if (uctrl == NULL)
 169                 return -EINVAL;
 170         return uctrl->sock;
 171 }
 172
 173 struct udev_ctrl_connection *udev_ctrl_get_connection(struct udev_ctrl *uctrl) {
 174         struct udev_ctrl_connection *conn;
 175         struct ucred ucred = {};
 176         const int on = 1;
 177         int r;
 178
 179         conn = new(struct udev_ctrl_connection, 1);
 180         if (conn == NULL)
 181                 return NULL;
 182         conn->refcount = 1;
 183         conn->uctrl = uctrl;
 184
 185         conn->sock = accept4(uctrl->sock, NULL, NULL, SOCK_CLOEXEC|SOCK_NONBLOCK);
 186         if (conn->sock < 0) {
 187                 if (errno != EINTR)
 188                         log_error_errno(errno, "unable to receive ctrl connection: %m");
 189                 goto err;
 190         }
 191
 192         /* check peer credential of connection */
 193         r = getpeercred(conn->sock, &ucred);
 194         if (r < 0) {
 195                 log_error_errno(r, "unable to receive credentials of ctrl connection: %m");
 196                 goto err;
 197         }
 198         if (ucred.uid > 0) {
 199                 log_error("sender uid="UID_FMT", message ignored", ucred.uid);
 200                 goto err;
 201         }
 202
 203         /* enable receiving of the sender credentials in the messages */
 204         r = setsockopt(conn->sock, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on));
 205         if (r < 0)
 206                 log_warning_errno(errno, "could not set SO_PASSCRED: %m");
 207
 208         udev_ctrl_ref(uctrl);
 209         return conn;
 210 err:
 211         if (conn->sock >= 0)
 212                 close(conn->sock);
 213         free(conn);
 214         return NULL;
 215 }
 216
 217 struct udev_ctrl_connection *udev_ctrl_connection_ref(struct udev_ctrl_connection *conn) {
 218         if (conn == NULL)
 219                 return NULL;
 220         conn->refcount++;
 221         return conn;
 222 }
 223
 224 struct udev_ctrl_connection *udev_ctrl_connection_unref(struct udev_ctrl_connection *conn) {
 225         if (conn && -- conn->refcount == 0) {
 226                 if (conn->sock >= 0)
 227                         close(conn->sock);
 228
 229                 udev_ctrl_unref(conn->uctrl);
 230
 231                 free(conn);
 232         }
 233
 234         return NULL;
 235 }
 236
 237 static int ctrl_send(struct udev_ctrl *uctrl, enum udev_ctrl_msg_type type, int intval, const char *buf, int timeout) {
 238         struct udev_ctrl_msg_wire ctrl_msg_wire;
 239         int err = 0;
 240
 241         memzero(&ctrl_msg_wire, sizeof(struct udev_ctrl_msg_wire));
 242         strcpy(ctrl_msg_wire.version, "udev-" VERSION);
 243         ctrl_msg_wire.magic = UDEV_CTRL_MAGIC;
 244         ctrl_msg_wire.type = type;
 245
 246         if (buf != NULL)
 247                 strscpy(ctrl_msg_wire.buf, sizeof(ctrl_msg_wire.buf), buf);
 248         else
 249                 ctrl_msg_wire.intval = intval;
 250
 251         if (!uctrl->connected) {
 252                 if (connect(uctrl->sock, &uctrl->saddr.sa, uctrl->addrlen) < 0) {
 253                         err = -errno;
 254                         goto out;
 255                 }
 256                 uctrl->connected = true;
 257         }
 258         if (send(uctrl->sock, &ctrl_msg_wire, sizeof(ctrl_msg_wire), 0) < 0) {
 259                 err = -errno;
 260                 goto out;
 261         }
 262
 263         /* wait for peer message handling or disconnect */
 264         for (;;) {
 265                 struct pollfd pfd[1];
 266                 int r;
 267
 268                 pfd[0].fd = uctrl->sock;
 269                 pfd[0].events = POLLIN;
 270                 r = poll(pfd, 1, timeout * MSEC_PER_SEC);
 271                 if (r  < 0) {
 272                         if (errno == EINTR)
 273                                 continue;
 274                         err = -errno;
 275                         break;
 276                 }
 277
 278                 if (r > 0 && pfd[0].revents & POLLERR) {
 279                         err = -EIO;
 280                         break;
 281                 }
 282
 283                 if (r == 0)
 284                         err = -ETIMEDOUT;
 285                 break;
 286         }
 287 out:
 288         return err;
 289 }
 290
 291 int udev_ctrl_send_set_log_level(struct udev_ctrl *uctrl, int priority, int timeout) {
 292         return ctrl_send(uctrl, UDEV_CTRL_SET_LOG_LEVEL, priority, NULL, timeout);
 293 }
 294
 295 int udev_ctrl_send_stop_exec_queue(struct udev_ctrl *uctrl, int timeout) {
 296         return ctrl_send(uctrl, UDEV_CTRL_STOP_EXEC_QUEUE, 0, NULL, timeout);
 297 }
 298
 299 int udev_ctrl_send_start_exec_queue(struct udev_ctrl *uctrl, int timeout) {
 300         return ctrl_send(uctrl, UDEV_CTRL_START_EXEC_QUEUE, 0, NULL, timeout);
 301 }
 302
 303 int udev_ctrl_send_reload(struct udev_ctrl *uctrl, int timeout) {
 304         return ctrl_send(uctrl, UDEV_CTRL_RELOAD, 0, NULL, timeout);
 305 }
 306
 307 int udev_ctrl_send_set_env(struct udev_ctrl *uctrl, const char *key, int timeout) {
 308         return ctrl_send(uctrl, UDEV_CTRL_SET_ENV, 0, key, timeout);
 309 }
 310
 311 int udev_ctrl_send_set_children_max(struct udev_ctrl *uctrl, int count, int timeout) {
 312         return ctrl_send(uctrl, UDEV_CTRL_SET_CHILDREN_MAX, count, NULL, timeout);
 313 }
 314
 315 int udev_ctrl_send_ping(struct udev_ctrl *uctrl, int timeout) {
 316         return ctrl_send(uctrl, UDEV_CTRL_PING, 0, NULL, timeout);
 317 }
 318
 319 int udev_ctrl_send_exit(struct udev_ctrl *uctrl, int timeout) {
 320         return ctrl_send(uctrl, UDEV_CTRL_EXIT, 0, NULL, timeout);
 321 }
 322
 323 struct udev_ctrl_msg *udev_ctrl_receive_msg(struct udev_ctrl_connection *conn) {
 324         struct udev_ctrl_msg *uctrl_msg;
 325         ssize_t size;
 326         struct cmsghdr *cmsg;
 327         struct iovec iov;
 328         char cred_msg[CMSG_SPACE(sizeof(struct ucred))];
 329         struct msghdr smsg = {
 330                 .msg_iov = &iov,
 331                 .msg_iovlen = 1,
 332                 .msg_control = cred_msg,
 333                 .msg_controllen = sizeof(cred_msg),
 334         };
 335         struct ucred *cred;
 336
 337         uctrl_msg = new0(struct udev_ctrl_msg, 1);
 338         if (uctrl_msg == NULL)
 339                 return NULL;
 340         uctrl_msg->refcount = 1;
 341         uctrl_msg->conn = conn;
 342         udev_ctrl_connection_ref(conn);
 343
 344         /* wait for the incoming message */
 345         for (;;) {
 346                 struct pollfd pfd[1];
 347                 int r;
 348
 349                 pfd[0].fd = conn->sock;
 350                 pfd[0].events = POLLIN;
 351
 352                 r = poll(pfd, 1, 10000);
 353                 if (r  < 0) {
 354                         if (errno == EINTR)
 355                                 continue;
 356                         goto err;
 357                 } else if (r == 0) {
 358                         log_error("timeout waiting for ctrl message");
 359                         goto err;
 360                 } else {
 361                         if (!(pfd[0].revents & POLLIN)) {
 362                                 log_error_errno(errno, "ctrl connection error: %m");
 363                                 goto err;
 364                         }
 365                 }
 366
 367                 break;
 368         }
 369
 370         iov.iov_base = &uctrl_msg->ctrl_msg_wire;
 371         iov.iov_len = sizeof(struct udev_ctrl_msg_wire);
 372
 373         size = recvmsg(conn->sock, &smsg, 0);
 374         if (size <  0) {
 375                 log_error_errno(errno, "unable to receive ctrl message: %m");
 376                 goto err;
 377         }
 378
 379         cmsg_close_all(&smsg);
 380
 381         cmsg = CMSG_FIRSTHDR(&smsg);
 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         cred = (struct ucred *) CMSG_DATA(cmsg);
 389
 390         if (cred->uid != 0) {
 391                 log_error("sender uid="UID_FMT", message ignored", cred->uid);
 392                 goto err;
 393         }
 394
 395         if (uctrl_msg->ctrl_msg_wire.magic != UDEV_CTRL_MAGIC) {
 396                 log_error("message magic 0x%08x doesn't match, ignore it", uctrl_msg->ctrl_msg_wire.magic);
 397                 goto err;
 398         }
 399
 400         return uctrl_msg;
 401 err:
 402         udev_ctrl_msg_unref(uctrl_msg);
 403         return NULL;
 404 }
 405
 406 struct udev_ctrl_msg *udev_ctrl_msg_unref(struct udev_ctrl_msg *ctrl_msg) {
 407         if (ctrl_msg && -- ctrl_msg->refcount == 0) {
 408                 udev_ctrl_connection_unref(ctrl_msg->conn);
 409                 free(ctrl_msg);
 410         }
 411
 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 }