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