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 <poll.h>
  14 #include <stddef.h>
  15 #include <stdlib.h>
  16 #include <string.h>
  17 #include <sys/socket.h>
  18 #include <sys/un.h>
  19 #include <unistd.h>
  20
  21 #include "alloc-util.h"
  22 #include "fd-util.h"
  23 #include "formats-util.h"
  24 #include "socket-util.h"
  25 #include "udev.h"
  26
  27 /* wire protocol magic must match */
  28 #define UDEV_CTRL_MAGIC                                0xdead1dea
  29
  30 enum udev_ctrl_msg_type {
  31         UDEV_CTRL_UNKNOWN,
  32         UDEV_CTRL_SET_LOG_LEVEL,
  33         UDEV_CTRL_STOP_EXEC_QUEUE,
  34         UDEV_CTRL_START_EXEC_QUEUE,
  35         UDEV_CTRL_RELOAD,
  36         UDEV_CTRL_SET_ENV,
  37         UDEV_CTRL_SET_CHILDREN_MAX,
  38         UDEV_CTRL_PING,
  39         UDEV_CTRL_EXIT,
  40 };
  41
  42 struct udev_ctrl_msg_wire {
  43         char version[16];
  44         unsigned int magic;
  45         enum udev_ctrl_msg_type type;
  46         union {
  47                 int intval;
  48                 char buf[256];
  49         };
  50 };
  51
  52 struct udev_ctrl_msg {
  53         int refcount;
  54         struct udev_ctrl_connection *conn;
  55         struct udev_ctrl_msg_wire ctrl_msg_wire;
  56 };
  57
  58 struct udev_ctrl {
  59         int refcount;
  60         struct udev *udev;
  61         int sock;
  62         union sockaddr_union saddr;
  63         socklen_t addrlen;
  64         bool bound;
  65         bool cleanup_socket;
  66         bool connected;
  67 };
  68
  69 struct udev_ctrl_connection {
  70         int refcount;
  71         struct udev_ctrl *uctrl;
  72         int sock;
  73 };
  74
  75 struct udev_ctrl *udev_ctrl_new_from_fd(struct udev *udev, int fd) {
  76         struct udev_ctrl *uctrl;
  77         const int on = 1;
  78         int r;
  79
  80         uctrl = new0(struct udev_ctrl, 1);
  81         if (uctrl == NULL)
  82                 return NULL;
  83         uctrl->refcount = 1;
  84         uctrl->udev = udev;
  85
  86         if (fd < 0) {
  87                 uctrl->sock = socket(AF_LOCAL, SOCK_SEQPACKET|SOCK_NONBLOCK|SOCK_CLOEXEC, 0);
  88                 if (uctrl->sock < 0) {
  89                         log_error_errno(errno, "error getting socket: %m");
  90                         udev_ctrl_unref(uctrl);
  91                         return NULL;
  92                 }
  93         } else {
  94                 uctrl->bound = true;
  95                 uctrl->sock = fd;
  96         }
  97
  98         /*
  99          * FIXME: remove it as soon as we can depend on this:
 100          *   http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=90c6bd34f884cd9cee21f1d152baf6c18bcac949
 101          */
 102         r = setsockopt(uctrl->sock, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on));
 103         if (r < 0)
 104                 log_warning_errno(errno, "could not set SO_PASSCRED: %m");
 105
 106         uctrl->saddr.un.sun_family = AF_LOCAL;
 107         strscpy(uctrl->saddr.un.sun_path, sizeof(uctrl->saddr.un.sun_path), "/run/udev/control");
 108         uctrl->addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(uctrl->saddr.un.sun_path);
 109         return uctrl;
 110 }
 111
 112 struct udev_ctrl *udev_ctrl_new(struct udev *udev) {
 113         return udev_ctrl_new_from_fd(udev, -1);
 114 }
 115
 116 int udev_ctrl_enable_receiving(struct udev_ctrl *uctrl) {
 117         int err;
 118
 119         if (!uctrl->bound) {
 120                 err = bind(uctrl->sock, &uctrl->saddr.sa, uctrl->addrlen);
 121                 if (err < 0 && errno == EADDRINUSE) {
 122                         unlink(uctrl->saddr.un.sun_path);
 123                         err = bind(uctrl->sock, &uctrl->saddr.sa, uctrl->addrlen);
 124                 }
 125
 126                 if (err < 0)
 127                         return log_error_errno(errno, "bind failed: %m");
 128
 129                 err = listen(uctrl->sock, 0);
 130                 if (err < 0)
 131                         return log_error_errno(errno, "listen failed: %m");
 132
 133                 uctrl->bound = true;
 134                 uctrl->cleanup_socket = true;
 135         }
 136         return 0;
 137 }
 138
 139 struct udev *udev_ctrl_get_udev(struct udev_ctrl *uctrl) {
 140         return uctrl->udev;
 141 }
 142
 143 static struct udev_ctrl *udev_ctrl_ref(struct udev_ctrl *uctrl) {
 144         if (uctrl)
 145                 uctrl->refcount++;
 146
 147         return uctrl;
 148 }
 149
 150 struct udev_ctrl *udev_ctrl_unref(struct udev_ctrl *uctrl) {
 151         if (uctrl && -- uctrl->refcount == 0) {
 152                 if (uctrl->sock >= 0)
 153                         close(uctrl->sock);
 154                 free(uctrl);
 155         }
 156
 157         return NULL;
 158 }
 159
 160 int udev_ctrl_cleanup(struct udev_ctrl *uctrl) {
 161         if (uctrl == NULL)
 162                 return 0;
 163         if (uctrl->cleanup_socket)
 164                 unlink(uctrl->saddr.un.sun_path);
 165         return 0;
 166 }
 167
 168 int udev_ctrl_get_fd(struct udev_ctrl *uctrl) {
 169         if (uctrl == NULL)
 170                 return -EINVAL;
 171         return uctrl->sock;
 172 }
 173
 174 struct udev_ctrl_connection *udev_ctrl_get_connection(struct udev_ctrl *uctrl) {
 175         struct udev_ctrl_connection *conn;
 176         struct ucred ucred = {};
 177         const int on = 1;
 178         int r;
 179
 180         conn = new(struct udev_ctrl_connection, 1);
 181         if (conn == NULL)
 182                 return NULL;
 183         conn->refcount = 1;
 184         conn->uctrl = uctrl;
 185
 186         conn->sock = accept4(uctrl->sock, NULL, NULL, SOCK_CLOEXEC|SOCK_NONBLOCK);
 187         if (conn->sock < 0) {
 188                 if (errno != EINTR)
 189                         log_error_errno(errno, "unable to receive ctrl connection: %m");
 190                 goto err;
 191         }
 192
 193         /* check peer credential of connection */
 194         r = getpeercred(conn->sock, &ucred);
 195         if (r < 0) {
 196                 log_error_errno(r, "unable to receive credentials of ctrl connection: %m");
 197                 goto err;
 198         }
 199         if (ucred.uid > 0) {
 200                 log_error("sender uid="UID_FMT", message ignored", ucred.uid);
 201                 goto err;
 202         }
 203
 204         /* enable receiving of the sender credentials in the messages */
 205         r = setsockopt(conn->sock, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on));
 206         if (r < 0)
 207                 log_warning_errno(errno, "could not set SO_PASSCRED: %m");
 208
 209         udev_ctrl_ref(uctrl);
 210         return conn;
 211 err:
 212         if (conn->sock >= 0)
 213                 close(conn->sock);
 214         free(conn);
 215         return NULL;
 216 }
 217
 218 struct udev_ctrl_connection *udev_ctrl_connection_ref(struct udev_ctrl_connection *conn) {
 219         if (conn == NULL)
 220                 return NULL;
 221         conn->refcount++;
 222         return conn;
 223 }
 224
 225 struct udev_ctrl_connection *udev_ctrl_connection_unref(struct udev_ctrl_connection *conn) {
 226         if (conn && -- conn->refcount == 0) {
 227                 if (conn->sock >= 0)
 228                         close(conn->sock);
 229
 230                 udev_ctrl_unref(conn->uctrl);
 231
 232                 free(conn);
 233         }
 234
 235         return NULL;
 236 }
 237
 238 static int ctrl_send(struct udev_ctrl *uctrl, enum udev_ctrl_msg_type type, int intval, const char *buf, int timeout) {
 239         struct udev_ctrl_msg_wire ctrl_msg_wire;
 240         int err = 0;
 241
 242         memzero(&ctrl_msg_wire, sizeof(struct udev_ctrl_msg_wire));
 243         strcpy(ctrl_msg_wire.version, "udev-" VERSION);
 244         ctrl_msg_wire.magic = UDEV_CTRL_MAGIC;
 245         ctrl_msg_wire.type = type;
 246
 247         if (buf != NULL)
 248                 strscpy(ctrl_msg_wire.buf, sizeof(ctrl_msg_wire.buf), buf);
 249         else
 250                 ctrl_msg_wire.intval = intval;
 251
 252         if (!uctrl->connected) {
 253                 if (connect(uctrl->sock, &uctrl->saddr.sa, uctrl->addrlen) < 0) {
 254                         err = -errno;
 255                         goto out;
 256                 }
 257                 uctrl->connected = true;
 258         }
 259         if (send(uctrl->sock, &ctrl_msg_wire, sizeof(ctrl_msg_wire), 0) < 0) {
 260                 err = -errno;
 261                 goto out;
 262         }
 263
 264         /* wait for peer message handling or disconnect */
 265         for (;;) {
 266                 struct pollfd pfd[1];
 267                 int r;
 268
 269                 pfd[0].fd = uctrl->sock;
 270                 pfd[0].events = POLLIN;
 271                 r = poll(pfd, 1, timeout * MSEC_PER_SEC);
 272                 if (r  < 0) {
 273                         if (errno == EINTR)
 274                                 continue;
 275                         err = -errno;
 276                         break;
 277                 }
 278
 279                 if (r > 0 && pfd[0].revents & POLLERR) {
 280                         err = -EIO;
 281                         break;
 282                 }
 283
 284                 if (r == 0)
 285                         err = -ETIMEDOUT;
 286                 break;
 287         }
 288 out:
 289         return err;
 290 }
 291
 292 int udev_ctrl_send_set_log_level(struct udev_ctrl *uctrl, int priority, int timeout) {
 293         return ctrl_send(uctrl, UDEV_CTRL_SET_LOG_LEVEL, priority, NULL, timeout);
 294 }
 295
 296 int udev_ctrl_send_stop_exec_queue(struct udev_ctrl *uctrl, int timeout) {
 297         return ctrl_send(uctrl, UDEV_CTRL_STOP_EXEC_QUEUE, 0, NULL, timeout);
 298 }
 299
 300 int udev_ctrl_send_start_exec_queue(struct udev_ctrl *uctrl, int timeout) {
 301         return ctrl_send(uctrl, UDEV_CTRL_START_EXEC_QUEUE, 0, NULL, timeout);
 302 }
 303
 304 int udev_ctrl_send_reload(struct udev_ctrl *uctrl, int timeout) {
 305         return ctrl_send(uctrl, UDEV_CTRL_RELOAD, 0, NULL, timeout);
 306 }
 307
 308 int udev_ctrl_send_set_env(struct udev_ctrl *uctrl, const char *key, int timeout) {
 309         return ctrl_send(uctrl, UDEV_CTRL_SET_ENV, 0, key, timeout);
 310 }
 311
 312 int udev_ctrl_send_set_children_max(struct udev_ctrl *uctrl, int count, int timeout) {
 313         return ctrl_send(uctrl, UDEV_CTRL_SET_CHILDREN_MAX, count, NULL, timeout);
 314 }
 315
 316 int udev_ctrl_send_ping(struct udev_ctrl *uctrl, int timeout) {
 317         return ctrl_send(uctrl, UDEV_CTRL_PING, 0, NULL, timeout);
 318 }
 319
 320 int udev_ctrl_send_exit(struct udev_ctrl *uctrl, int timeout) {
 321         return ctrl_send(uctrl, UDEV_CTRL_EXIT, 0, NULL, timeout);
 322 }
 323
 324 struct udev_ctrl_msg *udev_ctrl_receive_msg(struct udev_ctrl_connection *conn) {
 325         struct udev_ctrl_msg *uctrl_msg;
 326         ssize_t size;
 327         struct cmsghdr *cmsg;
 328         struct iovec iov;
 329         char cred_msg[CMSG_SPACE(sizeof(struct ucred))];
 330         struct msghdr smsg = {
 331                 .msg_iov = &iov,
 332                 .msg_iovlen = 1,
 333                 .msg_control = cred_msg,
 334                 .msg_controllen = sizeof(cred_msg),
 335         };
 336         struct ucred *cred;
 337
 338         uctrl_msg = new0(struct udev_ctrl_msg, 1);
 339         if (uctrl_msg == NULL)
 340                 return NULL;
 341         uctrl_msg->refcount = 1;
 342         uctrl_msg->conn = conn;
 343         udev_ctrl_connection_ref(conn);
 344
 345         /* wait for the incoming message */
 346         for (;;) {
 347                 struct pollfd pfd[1];
 348                 int r;
 349
 350                 pfd[0].fd = conn->sock;
 351                 pfd[0].events = POLLIN;
 352
 353                 r = poll(pfd, 1, 10000);
 354                 if (r  < 0) {
 355                         if (errno == EINTR)
 356                                 continue;
 357                         goto err;
 358                 } else if (r == 0) {
 359                         log_error("timeout waiting for ctrl message");
 360                         goto err;
 361                 } else {
 362                         if (!(pfd[0].revents & POLLIN)) {
 363                                 log_error_errno(errno, "ctrl connection error: %m");
 364                                 goto err;
 365                         }
 366                 }
 367
 368                 break;
 369         }
 370
 371         iov.iov_base = &uctrl_msg->ctrl_msg_wire;
 372         iov.iov_len = sizeof(struct udev_ctrl_msg_wire);
 373
 374         size = recvmsg(conn->sock, &smsg, 0);
 375         if (size <  0) {
 376                 log_error_errno(errno, "unable to receive ctrl message: %m");
 377                 goto err;
 378         }
 379
 380         cmsg_close_all(&smsg);
 381
 382         cmsg = CMSG_FIRSTHDR(&smsg);
 383
 384         if (cmsg == NULL || cmsg->cmsg_type != SCM_CREDENTIALS) {
 385                 log_error("no sender credentials received, message ignored");
 386                 goto err;
 387         }
 388
 389         cred = (struct ucred *) CMSG_DATA(cmsg);
 390
 391         if (cred->uid != 0) {
 392                 log_error("sender uid="UID_FMT", message ignored", cred->uid);
 393                 goto err;
 394         }
 395
 396         if (uctrl_msg->ctrl_msg_wire.magic != UDEV_CTRL_MAGIC) {
 397                 log_error("message magic 0x%08x doesn't match, ignore it", uctrl_msg->ctrl_msg_wire.magic);
 398                 goto err;
 399         }
 400
 401         return uctrl_msg;
 402 err:
 403         udev_ctrl_msg_unref(uctrl_msg);
 404         return NULL;
 405 }
 406
 407 struct udev_ctrl_msg *udev_ctrl_msg_unref(struct udev_ctrl_msg *ctrl_msg) {
 408         if (ctrl_msg && -- ctrl_msg->refcount == 0) {
 409                 udev_ctrl_connection_unref(ctrl_msg->conn);
 410                 free(ctrl_msg);
 411         }
 412
 413         return NULL;
 414 }
 415
 416 int udev_ctrl_get_set_log_level(struct udev_ctrl_msg *ctrl_msg) {
 417         if (ctrl_msg->ctrl_msg_wire.type == UDEV_CTRL_SET_LOG_LEVEL)
 418                 return ctrl_msg->ctrl_msg_wire.intval;
 419         return -1;
 420 }
 421
 422 int udev_ctrl_get_stop_exec_queue(struct udev_ctrl_msg *ctrl_msg) {
 423         if (ctrl_msg->ctrl_msg_wire.type == UDEV_CTRL_STOP_EXEC_QUEUE)
 424                 return 1;
 425         return -1;
 426 }
 427
 428 int udev_ctrl_get_start_exec_queue(struct udev_ctrl_msg *ctrl_msg) {
 429         if (ctrl_msg->ctrl_msg_wire.type == UDEV_CTRL_START_EXEC_QUEUE)
 430                 return 1;
 431         return -1;
 432 }
 433
 434 int udev_ctrl_get_reload(struct udev_ctrl_msg *ctrl_msg) {
 435         if (ctrl_msg->ctrl_msg_wire.type == UDEV_CTRL_RELOAD)
 436                 return 1;
 437         return -1;
 438 }
 439
 440 const char *udev_ctrl_get_set_env(struct udev_ctrl_msg *ctrl_msg) {
 441         if (ctrl_msg->ctrl_msg_wire.type == UDEV_CTRL_SET_ENV)
 442                 return ctrl_msg->ctrl_msg_wire.buf;
 443         return NULL;
 444 }
 445
 446 int udev_ctrl_get_set_children_max(struct udev_ctrl_msg *ctrl_msg) {
 447         if (ctrl_msg->ctrl_msg_wire.type == UDEV_CTRL_SET_CHILDREN_MAX)
 448                 return ctrl_msg->ctrl_msg_wire.intval;
 449         return -1;
 450 }
 451
 452 int udev_ctrl_get_ping(struct udev_ctrl_msg *ctrl_msg) {
 453         if (ctrl_msg->ctrl_msg_wire.type == UDEV_CTRL_PING)
 454                 return 1;
 455         return -1;
 456 }
 457
 458 int udev_ctrl_get_exit(struct udev_ctrl_msg *ctrl_msg) {
 459         if (ctrl_msg->ctrl_msg_wire.type == UDEV_CTRL_EXIT)
 460                 return 1;
 461         return -1;
 462 }