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 "io-util.h"
  24 #include "socket-util.h"
  25 #include "strxcpyx.h"
  26 #include "udev-ctrl.h"
  27
  28 /* wire protocol magic must match */
  29 #define UDEV_CTRL_MAGIC                                0xdead1dea
  30
  31 enum udev_ctrl_msg_type {
  32         UDEV_CTRL_UNKNOWN,
  33         UDEV_CTRL_SET_LOG_LEVEL,
  34         UDEV_CTRL_STOP_EXEC_QUEUE,
  35         UDEV_CTRL_START_EXEC_QUEUE,
  36         UDEV_CTRL_RELOAD,
  37         UDEV_CTRL_SET_ENV,
  38         UDEV_CTRL_SET_CHILDREN_MAX,
  39         UDEV_CTRL_PING,
  40         UDEV_CTRL_EXIT,
  41 };
  42
  43 struct udev_ctrl_msg_wire {
  44         char version[16];
  45         unsigned magic;
  46         enum udev_ctrl_msg_type type;
  47         union {
  48                 int intval;
  49                 char buf[256];
  50         };
  51 };
  52
  53 struct udev_ctrl_msg {
  54         unsigned n_ref;
  55         struct udev_ctrl_connection *conn;
  56         struct udev_ctrl_msg_wire ctrl_msg_wire;
  57 };
  58
  59 struct udev_ctrl {
  60         unsigned n_ref;
  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         unsigned n_ref;
  71         struct udev_ctrl *uctrl;
  72         int sock;
  73 };
  74
  75 struct udev_ctrl *udev_ctrl_new_from_fd(int fd) {
  76         struct udev_ctrl *uctrl;
  77         int r;
  78
  79         uctrl = new0(struct udev_ctrl, 1);
  80         if (!uctrl)
  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, "Failed to create 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_int(uctrl->sock, SOL_SOCKET, SO_PASSCRED, true);
 101         if (r < 0)
 102                 log_warning_errno(r, "Failed to set SO_PASSCRED: %m");
 103
 104         uctrl->saddr.un = (struct sockaddr_un) {
 105                 .sun_family = AF_UNIX,
 106                 .sun_path = "/run/udev/control",
 107         };
 108
 109         uctrl->addrlen = SOCKADDR_UN_LEN(uctrl->saddr.un);
 110         return uctrl;
 111 }
 112
 113 struct udev_ctrl *udev_ctrl_new(void) {
 114         return udev_ctrl_new_from_fd(-1);
 115 }
 116
 117 int udev_ctrl_enable_receiving(struct udev_ctrl *uctrl) {
 118         int err;
 119
 120         if (!uctrl->bound) {
 121                 err = bind(uctrl->sock, &uctrl->saddr.sa, uctrl->addrlen);
 122                 if (err < 0 && errno == EADDRINUSE) {
 123                         (void) sockaddr_un_unlink(&uctrl->saddr.un);
 124                         err = bind(uctrl->sock, &uctrl->saddr.sa, uctrl->addrlen);
 125                 }
 126
 127                 if (err < 0)
 128                         return log_error_errno(errno, "Failed to bind socket: %m");
 129
 130                 err = listen(uctrl->sock, 0);
 131                 if (err < 0)
 132                         return log_error_errno(errno, "Failed to listen: %m");
 133
 134                 uctrl->bound = true;
 135                 uctrl->cleanup_socket = true;
 136         }
 137         return 0;
 138 }
 139
 140 static struct udev_ctrl *udev_ctrl_free(struct udev_ctrl *uctrl) {
 141         assert(uctrl);
 142
 143         safe_close(uctrl->sock);
 144         return mfree(uctrl);
 145 }
 146
 147 DEFINE_PRIVATE_TRIVIAL_REF_FUNC(struct udev_ctrl, udev_ctrl);
 148 DEFINE_TRIVIAL_UNREF_FUNC(struct udev_ctrl, udev_ctrl, udev_ctrl_free);
 149
 150 int udev_ctrl_cleanup(struct udev_ctrl *uctrl) {
 151         if (!uctrl)
 152                 return 0;
 153         if (uctrl->cleanup_socket)
 154                 sockaddr_un_unlink(&uctrl->saddr.un);
 155         return 0;
 156 }
 157
 158 int udev_ctrl_get_fd(struct udev_ctrl *uctrl) {
 159         if (!uctrl)
 160                 return -EINVAL;
 161         return uctrl->sock;
 162 }
 163
 164 struct udev_ctrl_connection *udev_ctrl_get_connection(struct udev_ctrl *uctrl) {
 165         struct udev_ctrl_connection *conn;
 166         struct ucred ucred = {};
 167         int r;
 168
 169         conn = new(struct udev_ctrl_connection, 1);
 170         if (!conn)
 171                 return NULL;
 172         conn->n_ref = 1;
 173         conn->uctrl = uctrl;
 174
 175         conn->sock = accept4(uctrl->sock, NULL, NULL, SOCK_CLOEXEC|SOCK_NONBLOCK);
 176         if (conn->sock < 0) {
 177                 if (errno != EINTR)
 178                         log_error_errno(errno, "Failed to receive ctrl connection: %m");
 179                 goto err;
 180         }
 181
 182         /* check peer credential of connection */
 183         r = getpeercred(conn->sock, &ucred);
 184         if (r < 0) {
 185                 log_error_errno(r, "Failed to receive credentials of ctrl connection: %m");
 186                 goto err;
 187         }
 188         if (ucred.uid > 0) {
 189                 log_error("Sender uid="UID_FMT", message ignored", ucred.uid);
 190                 goto err;
 191         }
 192
 193         /* enable receiving of the sender credentials in the messages */
 194         r = setsockopt_int(conn->sock, SOL_SOCKET, SO_PASSCRED, true);
 195         if (r < 0)
 196                 log_warning_errno(r, "Failed to set SO_PASSCRED: %m");
 197
 198         udev_ctrl_ref(uctrl);
 199         return conn;
 200 err:
 201         safe_close(conn->sock);
 202         return mfree(conn);
 203 }
 204
 205 static struct udev_ctrl_connection *udev_ctrl_connection_free(struct udev_ctrl_connection *conn) {
 206         assert(conn);
 207
 208         safe_close(conn->sock);
 209         udev_ctrl_unref(conn->uctrl);
 210         return mfree(conn);
 211 }
 212
 213 DEFINE_TRIVIAL_REF_UNREF_FUNC(struct udev_ctrl_connection, udev_ctrl_connection, udev_ctrl_connection_free);
 214
 215 static int ctrl_send(struct udev_ctrl *uctrl, enum udev_ctrl_msg_type type, int intval, const char *buf, int timeout) {
 216         struct udev_ctrl_msg_wire ctrl_msg_wire;
 217         int err = 0;
 218
 219         memzero(&ctrl_msg_wire, sizeof(struct udev_ctrl_msg_wire));
 220         strcpy(ctrl_msg_wire.version, "udev-" PACKAGE_VERSION);
 221         ctrl_msg_wire.magic = UDEV_CTRL_MAGIC;
 222         ctrl_msg_wire.type = type;
 223
 224         if (buf)
 225                 strscpy(ctrl_msg_wire.buf, sizeof(ctrl_msg_wire.buf), buf);
 226         else
 227                 ctrl_msg_wire.intval = intval;
 228
 229         if (!uctrl->connected) {
 230                 if (connect(uctrl->sock, &uctrl->saddr.sa, uctrl->addrlen) < 0) {
 231                         err = -errno;
 232                         goto out;
 233                 }
 234                 uctrl->connected = true;
 235         }
 236         if (send(uctrl->sock, &ctrl_msg_wire, sizeof(ctrl_msg_wire), 0) < 0) {
 237                 err = -errno;
 238                 goto out;
 239         }
 240
 241         /* wait for peer message handling or disconnect */
 242         for (;;) {
 243                 struct pollfd pfd[1];
 244                 int r;
 245
 246                 pfd[0].fd = uctrl->sock;
 247                 pfd[0].events = POLLIN;
 248                 r = poll(pfd, 1, timeout * MSEC_PER_SEC);
 249                 if (r < 0) {
 250                         if (errno == EINTR)
 251                                 continue;
 252                         err = -errno;
 253                         break;
 254                 }
 255
 256                 if (r > 0 && pfd[0].revents & POLLERR) {
 257                         err = -EIO;
 258                         break;
 259                 }
 260
 261                 if (r == 0)
 262                         err = -ETIMEDOUT;
 263                 break;
 264         }
 265 out:
 266         return err;
 267 }
 268
 269 int udev_ctrl_send_set_log_level(struct udev_ctrl *uctrl, int priority, int timeout) {
 270         return ctrl_send(uctrl, UDEV_CTRL_SET_LOG_LEVEL, priority, NULL, timeout);
 271 }
 272
 273 int udev_ctrl_send_stop_exec_queue(struct udev_ctrl *uctrl, int timeout) {
 274         return ctrl_send(uctrl, UDEV_CTRL_STOP_EXEC_QUEUE, 0, NULL, timeout);
 275 }
 276
 277 int udev_ctrl_send_start_exec_queue(struct udev_ctrl *uctrl, int timeout) {
 278         return ctrl_send(uctrl, UDEV_CTRL_START_EXEC_QUEUE, 0, NULL, timeout);
 279 }
 280
 281 int udev_ctrl_send_reload(struct udev_ctrl *uctrl, int timeout) {
 282         return ctrl_send(uctrl, UDEV_CTRL_RELOAD, 0, NULL, timeout);
 283 }
 284
 285 int udev_ctrl_send_set_env(struct udev_ctrl *uctrl, const char *key, int timeout) {
 286         return ctrl_send(uctrl, UDEV_CTRL_SET_ENV, 0, key, timeout);
 287 }
 288
 289 int udev_ctrl_send_set_children_max(struct udev_ctrl *uctrl, int count, int timeout) {
 290         return ctrl_send(uctrl, UDEV_CTRL_SET_CHILDREN_MAX, count, NULL, timeout);
 291 }
 292
 293 int udev_ctrl_send_ping(struct udev_ctrl *uctrl, int timeout) {
 294         return ctrl_send(uctrl, UDEV_CTRL_PING, 0, NULL, timeout);
 295 }
 296
 297 int udev_ctrl_send_exit(struct udev_ctrl *uctrl, int timeout) {
 298         return ctrl_send(uctrl, UDEV_CTRL_EXIT, 0, NULL, timeout);
 299 }
 300
 301 struct udev_ctrl_msg *udev_ctrl_receive_msg(struct udev_ctrl_connection *conn) {
 302         struct udev_ctrl_msg *uctrl_msg;
 303         ssize_t size;
 304         struct cmsghdr *cmsg;
 305         struct iovec iov;
 306         char cred_msg[CMSG_SPACE(sizeof(struct ucred))];
 307         struct msghdr smsg = {
 308                 .msg_iov = &iov,
 309                 .msg_iovlen = 1,
 310                 .msg_control = cred_msg,
 311                 .msg_controllen = sizeof(cred_msg),
 312         };
 313         struct ucred *cred;
 314
 315         uctrl_msg = new0(struct udev_ctrl_msg, 1);
 316         if (!uctrl_msg)
 317                 return NULL;
 318         uctrl_msg->n_ref = 1;
 319         uctrl_msg->conn = conn;
 320         udev_ctrl_connection_ref(conn);
 321
 322         /* wait for the incoming message */
 323         for (;;) {
 324                 struct pollfd pfd[1];
 325                 int r;
 326
 327                 pfd[0].fd = conn->sock;
 328                 pfd[0].events = POLLIN;
 329
 330                 r = poll(pfd, 1, 10000);
 331                 if (r < 0) {
 332                         if (errno == EINTR)
 333                                 continue;
 334                         goto err;
 335                 } else if (r == 0) {
 336                         log_error("Timeout waiting for ctrl message");
 337                         goto err;
 338                 } else {
 339                         if (!(pfd[0].revents & POLLIN)) {
 340                                 log_error("Invalid ctrl connection: %m");
 341                                 goto err;
 342                         }
 343                 }
 344
 345                 break;
 346         }
 347
 348         iov = IOVEC_MAKE(&uctrl_msg->ctrl_msg_wire, sizeof(struct udev_ctrl_msg_wire));
 349
 350         size = recvmsg(conn->sock, &smsg, 0);
 351         if (size < 0) {
 352                 log_error_errno(errno, "Failed 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 || cmsg->cmsg_type != SCM_CREDENTIALS) {
 361                 log_error("No sender credentials received, ignoring message");
 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", ignoring message", 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, ignoring", 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 }