src/udev/udev-ctrl.c

   1 /* SPDX-License-Identifier: LGPL-2.1+
   2  *
   3  * libudev - interface to udev device information
   4  *
   5  * This library is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU Lesser General Public
   7  * License as published by the Free Software Foundation; either
   8  * version 2.1 of the License, or (at your option) any later version.
   9  */
  10
  11 #include <errno.h>
  12 #include <poll.h>
  13 #include <stddef.h>
  14 #include <stdlib.h>
  15 #include <string.h>
  16 #include <sys/socket.h>
  17 #include <sys/un.h>
  18 #include <unistd.h>
  19
  20 #include "alloc-util.h"
  21 #include "fd-util.h"
  22 #include "format-util.h"
  23 #include "socket-util.h"
  24 #include "strxcpyx.h"
  25 #include "udev-ctrl.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         unsigned n_ref;
  54         struct udev_ctrl_connection *conn;
  55         struct udev_ctrl_msg_wire ctrl_msg_wire;
  56 };
  57
  58 struct udev_ctrl {
  59         unsigned n_ref;
  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         unsigned n_ref;
  70         struct udev_ctrl *uctrl;
  71         int sock;
  72 };
  73
  74 struct udev_ctrl *udev_ctrl_new_from_fd(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->n_ref = 1;
  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_errno(errno, "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
  96         /*
  97          * FIXME: remove it as soon as we can depend on this:
  98          *   http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=90c6bd34f884cd9cee21f1d152baf6c18bcac949
  99          */
 100         r = setsockopt(uctrl->sock, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on));
 101         if (r < 0)
 102                 log_warning_errno(errno, "could not set SO_PASSCRED: %m");
 103
 104         uctrl->saddr.un.sun_family = AF_LOCAL;
 105         strscpy(uctrl->saddr.un.sun_path, sizeof(uctrl->saddr.un.sun_path), "/run/udev/control");
 106         uctrl->addrlen = SOCKADDR_UN_LEN(uctrl->saddr.un);
 107         return uctrl;
 108 }
 109
 110 struct udev_ctrl *udev_ctrl_new(void) {
 111         return udev_ctrl_new_from_fd(-1);
 112 }
 113
 114 int udev_ctrl_enable_receiving(struct udev_ctrl *uctrl) {
 115         int err;
 116
 117         if (!uctrl->bound) {
 118                 err = bind(uctrl->sock, &uctrl->saddr.sa, uctrl->addrlen);
 119                 if (err < 0 && errno == EADDRINUSE) {
 120                         unlink(uctrl->saddr.un.sun_path);
 121                         err = bind(uctrl->sock, &uctrl->saddr.sa, uctrl->addrlen);
 122                 }
 123
 124                 if (err < 0)
 125                         return log_error_errno(errno, "bind failed: %m");
 126
 127                 err = listen(uctrl->sock, 0);
 128                 if (err < 0)
 129                         return log_error_errno(errno, "listen failed: %m");
 130
 131                 uctrl->bound = true;
 132                 uctrl->cleanup_socket = true;
 133         }
 134         return 0;
 135 }
 136
 137 static struct udev_ctrl *udev_ctrl_free(struct udev_ctrl *uctrl) {
 138         assert(uctrl);
 139
 140         safe_close(uctrl->sock);
 141         return mfree(uctrl);
 142 }
 143
 144 DEFINE_PRIVATE_TRIVIAL_REF_FUNC(struct udev_ctrl, udev_ctrl);
 145 DEFINE_TRIVIAL_UNREF_FUNC(struct udev_ctrl, udev_ctrl, udev_ctrl_free);
 146
 147 int udev_ctrl_cleanup(struct udev_ctrl *uctrl) {
 148         if (uctrl == NULL)
 149                 return 0;
 150         if (uctrl->cleanup_socket)
 151                 unlink(uctrl->saddr.un.sun_path);
 152         return 0;
 153 }
 154
 155 int udev_ctrl_get_fd(struct udev_ctrl *uctrl) {
 156         if (uctrl == NULL)
 157                 return -EINVAL;
 158         return uctrl->sock;
 159 }
 160
 161 struct udev_ctrl_connection *udev_ctrl_get_connection(struct udev_ctrl *uctrl) {
 162         struct udev_ctrl_connection *conn;
 163         struct ucred ucred = {};
 164         const int on = 1;
 165         int r;
 166
 167         conn = new(struct udev_ctrl_connection, 1);
 168         if (conn == NULL)
 169                 return NULL;
 170         conn->n_ref = 1;
 171         conn->uctrl = uctrl;
 172
 173         conn->sock = accept4(uctrl->sock, NULL, NULL, SOCK_CLOEXEC|SOCK_NONBLOCK);
 174         if (conn->sock < 0) {
 175                 if (errno != EINTR)
 176                         log_error_errno(errno, "unable to receive ctrl connection: %m");
 177                 goto err;
 178         }
 179
 180         /* check peer credential of connection */
 181         r = getpeercred(conn->sock, &ucred);
 182         if (r < 0) {
 183                 log_error_errno(r, "unable to receive credentials of ctrl connection: %m");
 184                 goto err;
 185         }
 186         if (ucred.uid > 0) {
 187                 log_error("sender uid="UID_FMT", message ignored", ucred.uid);
 188                 goto err;
 189         }
 190
 191         /* enable receiving of the sender credentials in the messages */
 192         r = setsockopt(conn->sock, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on));
 193         if (r < 0)
 194                 log_warning_errno(errno, "could not set SO_PASSCRED: %m");
 195
 196         udev_ctrl_ref(uctrl);
 197         return conn;
 198 err:
 199         if (conn->sock >= 0)
 200                 close(conn->sock);
 201         return mfree(conn);
 202 }
 203
 204 static struct udev_ctrl_connection *udev_ctrl_connection_free(struct udev_ctrl_connection *conn) {
 205         assert(conn);
 206
 207         safe_close(conn->sock);
 208         udev_ctrl_unref(conn->uctrl);
 209         return mfree(conn);
 210 }
 211
 212 DEFINE_TRIVIAL_REF_UNREF_FUNC(struct udev_ctrl_connection, udev_ctrl_connection, udev_ctrl_connection_free);
 213
 214 static int ctrl_send(struct udev_ctrl *uctrl, enum udev_ctrl_msg_type type, int intval, const char *buf, int timeout) {
 215         struct udev_ctrl_msg_wire ctrl_msg_wire;
 216         int err = 0;
 217
 218         memzero(&ctrl_msg_wire, sizeof(struct udev_ctrl_msg_wire));
 219         strcpy(ctrl_msg_wire.version, "udev-" PACKAGE_VERSION);
 220         ctrl_msg_wire.magic = UDEV_CTRL_MAGIC;
 221         ctrl_msg_wire.type = type;
 222
 223         if (buf != NULL)
 224                 strscpy(ctrl_msg_wire.buf, sizeof(ctrl_msg_wire.buf), buf);
 225         else
 226                 ctrl_msg_wire.intval = intval;
 227
 228         if (!uctrl->connected) {
 229                 if (connect(uctrl->sock, &uctrl->saddr.sa, uctrl->addrlen) < 0) {
 230                         err = -errno;
 231                         goto out;
 232                 }
 233                 uctrl->connected = true;
 234         }
 235         if (send(uctrl->sock, &ctrl_msg_wire, sizeof(ctrl_msg_wire), 0) < 0) {
 236                 err = -errno;
 237                 goto out;
 238         }
 239
 240         /* wait for peer message handling or disconnect */
 241         for (;;) {
 242                 struct pollfd pfd[1];
 243                 int r;
 244
 245                 pfd[0].fd = uctrl->sock;
 246                 pfd[0].events = POLLIN;
 247                 r = poll(pfd, 1, timeout * MSEC_PER_SEC);
 248                 if (r  < 0) {
 249                         if (errno == EINTR)
 250                                 continue;
 251                         err = -errno;
 252                         break;
 253                 }
 254
 255                 if (r > 0 && pfd[0].revents & POLLERR) {
 256                         err = -EIO;
 257                         break;
 258                 }
 259
 260                 if (r == 0)
 261                         err = -ETIMEDOUT;
 262                 break;
 263         }
 264 out:
 265         return err;
 266 }
 267
 268 int udev_ctrl_send_set_log_level(struct udev_ctrl *uctrl, int priority, int timeout) {
 269         return ctrl_send(uctrl, UDEV_CTRL_SET_LOG_LEVEL, priority, NULL, timeout);
 270 }
 271
 272 int udev_ctrl_send_stop_exec_queue(struct udev_ctrl *uctrl, int timeout) {
 273         return ctrl_send(uctrl, UDEV_CTRL_STOP_EXEC_QUEUE, 0, NULL, timeout);
 274 }
 275
 276 int udev_ctrl_send_start_exec_queue(struct udev_ctrl *uctrl, int timeout) {
 277         return ctrl_send(uctrl, UDEV_CTRL_START_EXEC_QUEUE, 0, NULL, timeout);
 278 }
 279
 280 int udev_ctrl_send_reload(struct udev_ctrl *uctrl, int timeout) {
 281         return ctrl_send(uctrl, UDEV_CTRL_RELOAD, 0, NULL, timeout);
 282 }
 283
 284 int udev_ctrl_send_set_env(struct udev_ctrl *uctrl, const char *key, int timeout) {
 285         return ctrl_send(uctrl, UDEV_CTRL_SET_ENV, 0, key, timeout);
 286 }
 287
 288 int udev_ctrl_send_set_children_max(struct udev_ctrl *uctrl, int count, int timeout) {
 289         return ctrl_send(uctrl, UDEV_CTRL_SET_CHILDREN_MAX, count, NULL, timeout);
 290 }
 291
 292 int udev_ctrl_send_ping(struct udev_ctrl *uctrl, int timeout) {
 293         return ctrl_send(uctrl, UDEV_CTRL_PING, 0, NULL, timeout);
 294 }
 295
 296 int udev_ctrl_send_exit(struct udev_ctrl *uctrl, int timeout) {
 297         return ctrl_send(uctrl, UDEV_CTRL_EXIT, 0, NULL, timeout);
 298 }
 299
 300 struct udev_ctrl_msg *udev_ctrl_receive_msg(struct udev_ctrl_connection *conn) {
 301         struct udev_ctrl_msg *uctrl_msg;
 302         ssize_t size;
 303         struct cmsghdr *cmsg;
 304         struct iovec iov;
 305         char cred_msg[CMSG_SPACE(sizeof(struct ucred))];
 306         struct msghdr smsg = {
 307                 .msg_iov = &iov,
 308                 .msg_iovlen = 1,
 309                 .msg_control = cred_msg,
 310                 .msg_controllen = sizeof(cred_msg),
 311         };
 312         struct ucred *cred;
 313
 314         uctrl_msg = new0(struct udev_ctrl_msg, 1);
 315         if (uctrl_msg == NULL)
 316                 return NULL;
 317         uctrl_msg->n_ref = 1;
 318         uctrl_msg->conn = conn;
 319         udev_ctrl_connection_ref(conn);
 320
 321         /* wait for the incoming message */
 322         for (;;) {
 323                 struct pollfd pfd[1];
 324                 int r;
 325
 326                 pfd[0].fd = conn->sock;
 327                 pfd[0].events = POLLIN;
 328
 329                 r = poll(pfd, 1, 10000);
 330                 if (r  < 0) {
 331                         if (errno == EINTR)
 332                                 continue;
 333                         goto err;
 334                 } else if (r == 0) {
 335                         log_error("timeout waiting for ctrl message");
 336                         goto err;
 337                 } else {
 338                         if (!(pfd[0].revents & POLLIN)) {
 339                                 log_error_errno(errno, "ctrl connection error: %m");
 340                                 goto err;
 341                         }
 342                 }
 343
 344                 break;
 345         }
 346
 347         iov.iov_base = &uctrl_msg->ctrl_msg_wire;
 348         iov.iov_len = sizeof(struct udev_ctrl_msg_wire);
 349
 350         size = recvmsg(conn->sock, &smsg, 0);
 351         if (size <  0) {
 352                 log_error_errno(errno, "unable to receive ctrl message: %m");
 353                 goto err;
 354         }
 355
 356         cmsg_close_all(&smsg);
 357
 358         cmsg = CMSG_FIRSTHDR(&smsg);
 359
 360         if (cmsg == NULL || cmsg->cmsg_type != SCM_CREDENTIALS) {
 361                 log_error("no sender credentials received, message ignored");
 362                 goto err;
 363         }
 364
 365         cred = (struct ucred *) CMSG_DATA(cmsg);
 366
 367         if (cred->uid != 0) {
 368                 log_error("sender uid="UID_FMT", message ignored", cred->uid);
 369                 goto err;
 370         }
 371
 372         if (uctrl_msg->ctrl_msg_wire.magic != UDEV_CTRL_MAGIC) {
 373                 log_error("message magic 0x%08x doesn't match, ignore it", uctrl_msg->ctrl_msg_wire.magic);
 374                 goto err;
 375         }
 376
 377         return uctrl_msg;
 378 err:
 379         udev_ctrl_msg_unref(uctrl_msg);
 380         return NULL;
 381 }
 382
 383 static struct udev_ctrl_msg *udev_ctrl_msg_free(struct udev_ctrl_msg *ctrl_msg) {
 384         assert(ctrl_msg);
 385
 386         udev_ctrl_connection_unref(ctrl_msg->conn);
 387         return mfree(ctrl_msg);
 388 }
 389
 390 DEFINE_TRIVIAL_UNREF_FUNC(struct udev_ctrl_msg, udev_ctrl_msg, udev_ctrl_msg_free);
 391
 392 int udev_ctrl_get_set_log_level(struct udev_ctrl_msg *ctrl_msg) {
 393         if (ctrl_msg->ctrl_msg_wire.type == UDEV_CTRL_SET_LOG_LEVEL)
 394                 return ctrl_msg->ctrl_msg_wire.intval;
 395         return -1;
 396 }
 397
 398 int udev_ctrl_get_stop_exec_queue(struct udev_ctrl_msg *ctrl_msg) {
 399         if (ctrl_msg->ctrl_msg_wire.type == UDEV_CTRL_STOP_EXEC_QUEUE)
 400                 return 1;
 401         return -1;
 402 }
 403
 404 int udev_ctrl_get_start_exec_queue(struct udev_ctrl_msg *ctrl_msg) {
 405         if (ctrl_msg->ctrl_msg_wire.type == UDEV_CTRL_START_EXEC_QUEUE)
 406                 return 1;
 407         return -1;
 408 }
 409
 410 int udev_ctrl_get_reload(struct udev_ctrl_msg *ctrl_msg) {
 411         if (ctrl_msg->ctrl_msg_wire.type == UDEV_CTRL_RELOAD)
 412                 return 1;
 413         return -1;
 414 }
 415
 416 const char *udev_ctrl_get_set_env(struct udev_ctrl_msg *ctrl_msg) {
 417         if (ctrl_msg->ctrl_msg_wire.type == UDEV_CTRL_SET_ENV)
 418                 return ctrl_msg->ctrl_msg_wire.buf;
 419         return NULL;
 420 }
 421
 422 int udev_ctrl_get_set_children_max(struct udev_ctrl_msg *ctrl_msg) {
 423         if (ctrl_msg->ctrl_msg_wire.type == UDEV_CTRL_SET_CHILDREN_MAX)
 424                 return ctrl_msg->ctrl_msg_wire.intval;
 425         return -1;
 426 }
 427
 428 int udev_ctrl_get_ping(struct udev_ctrl_msg *ctrl_msg) {
 429         if (ctrl_msg->ctrl_msg_wire.type == UDEV_CTRL_PING)
 430                 return 1;
 431         return -1;
 432 }
 433
 434 int udev_ctrl_get_exit(struct udev_ctrl_msg *ctrl_msg) {
 435         if (ctrl_msg->ctrl_msg_wire.type == UDEV_CTRL_EXIT)
 436                 return 1;
 437         return -1;
 438 }