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 #include "util.h"
  28
  29 /* wire protocol magic must match */
  30 #define UDEV_CTRL_MAGIC                                0xdead1dea
  31
  32 enum udev_ctrl_msg_type {
  33         UDEV_CTRL_UNKNOWN,
  34         UDEV_CTRL_SET_LOG_LEVEL,
  35         UDEV_CTRL_STOP_EXEC_QUEUE,
  36         UDEV_CTRL_START_EXEC_QUEUE,
  37         UDEV_CTRL_RELOAD,
  38         UDEV_CTRL_SET_ENV,
  39         UDEV_CTRL_SET_CHILDREN_MAX,
  40         UDEV_CTRL_PING,
  41         UDEV_CTRL_EXIT,
  42 };
  43
  44 struct udev_ctrl_msg_wire {
  45         char version[16];
  46         unsigned magic;
  47         enum udev_ctrl_msg_type type;
  48         union {
  49                 int intval;
  50                 char buf[256];
  51         };
  52 };
  53
  54 struct udev_ctrl_msg {
  55         unsigned n_ref;
  56         struct udev_ctrl_connection *conn;
  57         struct udev_ctrl_msg_wire ctrl_msg_wire;
  58 };
  59
  60 struct udev_ctrl {
  61         unsigned n_ref;
  62         int sock;
  63         union sockaddr_union saddr;
  64         socklen_t addrlen;
  65         bool bound;
  66         bool cleanup_socket;
  67         bool connected;
  68 };
  69
  70 struct udev_ctrl_connection {
  71         unsigned n_ref;
  72         struct udev_ctrl *uctrl;
  73         int sock;
  74 };
  75
  76 struct udev_ctrl *udev_ctrl_new_from_fd(int fd) {
  77         struct udev_ctrl *uctrl;
  78         int r;
  79
  80         uctrl = new0(struct udev_ctrl, 1);
  81         if (!uctrl)
  82                 return NULL;
  83         uctrl->n_ref = 1;
  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, "Failed to create 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_int(uctrl->sock, SOL_SOCKET, SO_PASSCRED, true);
 102         if (r < 0)
 103                 log_warning_errno(r, "Failed to set SO_PASSCRED: %m");
 104
 105         uctrl->saddr.un = (struct sockaddr_un) {
 106                 .sun_family = AF_UNIX,
 107                 .sun_path = "/run/udev/control",
 108         };
 109
 110         uctrl->addrlen = SOCKADDR_UN_LEN(uctrl->saddr.un);
 111         return uctrl;
 112 }
 113
 114 struct udev_ctrl *udev_ctrl_new(void) {
 115         return udev_ctrl_new_from_fd(-1);
 116 }
 117
 118 int udev_ctrl_enable_receiving(struct udev_ctrl *uctrl) {
 119         int err;
 120
 121         if (!uctrl->bound) {
 122                 err = bind(uctrl->sock, &uctrl->saddr.sa, uctrl->addrlen);
 123                 if (err < 0 && errno == EADDRINUSE) {
 124                         (void) sockaddr_un_unlink(&uctrl->saddr.un);
 125                         err = bind(uctrl->sock, &uctrl->saddr.sa, uctrl->addrlen);
 126                 }
 127
 128                 if (err < 0)
 129                         return log_error_errno(errno, "Failed to bind socket: %m");
 130
 131                 err = listen(uctrl->sock, 0);
 132                 if (err < 0)
 133                         return log_error_errno(errno, "Failed to listen: %m");
 134
 135                 uctrl->bound = true;
 136                 uctrl->cleanup_socket = true;
 137         }
 138         return 0;
 139 }
 140
 141 static struct udev_ctrl *udev_ctrl_free(struct udev_ctrl *uctrl) {
 142         assert(uctrl);
 143
 144         safe_close(uctrl->sock);
 145         return mfree(uctrl);
 146 }
 147
 148 DEFINE_PRIVATE_TRIVIAL_REF_FUNC(struct udev_ctrl, udev_ctrl);
 149 DEFINE_TRIVIAL_UNREF_FUNC(struct udev_ctrl, udev_ctrl, udev_ctrl_free);
 150
 151 int udev_ctrl_cleanup(struct udev_ctrl *uctrl) {
 152         if (!uctrl)
 153                 return 0;
 154         if (uctrl->cleanup_socket)
 155                 sockaddr_un_unlink(&uctrl->saddr.un);
 156         return 0;
 157 }
 158
 159 int udev_ctrl_get_fd(struct udev_ctrl *uctrl) {
 160         if (!uctrl)
 161                 return -EINVAL;
 162         return uctrl->sock;
 163 }
 164
 165 struct udev_ctrl_connection *udev_ctrl_get_connection(struct udev_ctrl *uctrl) {
 166         struct udev_ctrl_connection *conn;
 167         struct ucred ucred = {};
 168         int r;
 169
 170         conn = new(struct udev_ctrl_connection, 1);
 171         if (!conn)
 172                 return NULL;
 173         conn->n_ref = 1;
 174         conn->uctrl = uctrl;
 175
 176         conn->sock = accept4(uctrl->sock, NULL, NULL, SOCK_CLOEXEC|SOCK_NONBLOCK);
 177         if (conn->sock < 0) {
 178                 if (errno != EINTR)
 179                         log_error_errno(errno, "Failed to receive ctrl connection: %m");
 180                 goto err;
 181         }
 182
 183         /* check peer credential of connection */
 184         r = getpeercred(conn->sock, &ucred);
 185         if (r < 0) {
 186                 log_error_errno(r, "Failed to receive credentials of ctrl connection: %m");
 187                 goto err;
 188         }
 189         if (ucred.uid > 0) {
 190                 log_error("Sender uid="UID_FMT", message ignored", ucred.uid);
 191                 goto err;
 192         }
 193
 194         /* enable receiving of the sender credentials in the messages */
 195         r = setsockopt_int(conn->sock, SOL_SOCKET, SO_PASSCRED, true);
 196         if (r < 0)
 197                 log_warning_errno(r, "Failed to set SO_PASSCRED: %m");
 198
 199         udev_ctrl_ref(uctrl);
 200         return conn;
 201 err:
 202         safe_close(conn->sock);
 203         return mfree(conn);
 204 }
 205
 206 static struct udev_ctrl_connection *udev_ctrl_connection_free(struct udev_ctrl_connection *conn) {
 207         assert(conn);
 208
 209         safe_close(conn->sock);
 210         udev_ctrl_unref(conn->uctrl);
 211         return mfree(conn);
 212 }
 213
 214 DEFINE_TRIVIAL_REF_UNREF_FUNC(struct udev_ctrl_connection, udev_ctrl_connection, udev_ctrl_connection_free);
 215
 216 static int ctrl_send(struct udev_ctrl *uctrl, enum udev_ctrl_msg_type type, int intval, const char *buf, usec_t timeout) {
 217         struct udev_ctrl_msg_wire ctrl_msg_wire = {
 218                 .version = "udev-" STRINGIFY(PROJECT_VERSION),
 219                 .magic = UDEV_CTRL_MAGIC,
 220                 .type = type,
 221         };
 222
 223         if (buf)
 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                         return -errno;
 231                 uctrl->connected = true;
 232         }
 233         if (send(uctrl->sock, &ctrl_msg_wire, sizeof(ctrl_msg_wire), 0) < 0)
 234                 return -errno;
 235
 236         /* wait for peer message handling or disconnect */
 237         for (;;) {
 238                 struct pollfd pfd = {
 239                         .fd = uctrl->sock,
 240                         .events = POLLIN,
 241                 };
 242                 int r;
 243
 244                 r = poll(&pfd, 1, DIV_ROUND_UP(timeout, USEC_PER_MSEC));
 245                 if (r < 0) {
 246                         if (errno == EINTR)
 247                                 continue;
 248                         return -errno;
 249                 }
 250                 if (r == 0)
 251                         return -ETIMEDOUT;
 252                 if (pfd.revents & POLLERR)
 253                         return -EIO;
 254                 return 0;
 255         }
 256 }
 257
 258 int udev_ctrl_send_set_log_level(struct udev_ctrl *uctrl, int priority, usec_t timeout) {
 259         return ctrl_send(uctrl, UDEV_CTRL_SET_LOG_LEVEL, priority, NULL, timeout);
 260 }
 261
 262 int udev_ctrl_send_stop_exec_queue(struct udev_ctrl *uctrl, usec_t timeout) {
 263         return ctrl_send(uctrl, UDEV_CTRL_STOP_EXEC_QUEUE, 0, NULL, timeout);
 264 }
 265
 266 int udev_ctrl_send_start_exec_queue(struct udev_ctrl *uctrl, usec_t timeout) {
 267         return ctrl_send(uctrl, UDEV_CTRL_START_EXEC_QUEUE, 0, NULL, timeout);
 268 }
 269
 270 int udev_ctrl_send_reload(struct udev_ctrl *uctrl, usec_t timeout) {
 271         return ctrl_send(uctrl, UDEV_CTRL_RELOAD, 0, NULL, timeout);
 272 }
 273
 274 int udev_ctrl_send_set_env(struct udev_ctrl *uctrl, const char *key, usec_t timeout) {
 275         return ctrl_send(uctrl, UDEV_CTRL_SET_ENV, 0, key, timeout);
 276 }
 277
 278 int udev_ctrl_send_set_children_max(struct udev_ctrl *uctrl, int count, usec_t timeout) {
 279         return ctrl_send(uctrl, UDEV_CTRL_SET_CHILDREN_MAX, count, NULL, timeout);
 280 }
 281
 282 int udev_ctrl_send_ping(struct udev_ctrl *uctrl, usec_t timeout) {
 283         return ctrl_send(uctrl, UDEV_CTRL_PING, 0, NULL, timeout);
 284 }
 285
 286 int udev_ctrl_send_exit(struct udev_ctrl *uctrl, usec_t timeout) {
 287         return ctrl_send(uctrl, UDEV_CTRL_EXIT, 0, NULL, timeout);
 288 }
 289
 290 struct udev_ctrl_msg *udev_ctrl_receive_msg(struct udev_ctrl_connection *conn) {
 291         struct udev_ctrl_msg *uctrl_msg;
 292         ssize_t size;
 293         struct cmsghdr *cmsg;
 294         struct iovec iov;
 295         char cred_msg[CMSG_SPACE(sizeof(struct ucred))];
 296         struct msghdr smsg = {
 297                 .msg_iov = &iov,
 298                 .msg_iovlen = 1,
 299                 .msg_control = cred_msg,
 300                 .msg_controllen = sizeof(cred_msg),
 301         };
 302         struct ucred *cred;
 303
 304         uctrl_msg = new0(struct udev_ctrl_msg, 1);
 305         if (!uctrl_msg)
 306                 return NULL;
 307         uctrl_msg->n_ref = 1;
 308         uctrl_msg->conn = conn;
 309         udev_ctrl_connection_ref(conn);
 310
 311         /* wait for the incoming message */
 312         for (;;) {
 313                 struct pollfd pfd[1];
 314                 int r;
 315
 316                 pfd[0].fd = conn->sock;
 317                 pfd[0].events = POLLIN;
 318
 319                 r = poll(pfd, 1, 10000);
 320                 if (r < 0) {
 321                         if (errno == EINTR)
 322                                 continue;
 323                         goto err;
 324                 } else if (r == 0) {
 325                         log_error("Timeout waiting for ctrl message");
 326                         goto err;
 327                 } else {
 328                         if (!(pfd[0].revents & POLLIN)) {
 329                                 log_error("Invalid ctrl connection: %m");
 330                                 goto err;
 331                         }
 332                 }
 333
 334                 break;
 335         }
 336
 337         iov = IOVEC_MAKE(&uctrl_msg->ctrl_msg_wire, sizeof(struct udev_ctrl_msg_wire));
 338
 339         size = recvmsg(conn->sock, &smsg, 0);
 340         if (size < 0) {
 341                 log_error_errno(errno, "Failed to receive ctrl message: %m");
 342                 goto err;
 343         }
 344
 345         cmsg_close_all(&smsg);
 346
 347         cmsg = CMSG_FIRSTHDR(&smsg);
 348
 349         if (!cmsg || cmsg->cmsg_type != SCM_CREDENTIALS) {
 350                 log_error("No sender credentials received, ignoring message");
 351                 goto err;
 352         }
 353
 354         cred = (struct ucred *) CMSG_DATA(cmsg);
 355
 356         if (cred->uid != 0) {
 357                 log_error("Sender uid="UID_FMT", ignoring message", cred->uid);
 358                 goto err;
 359         }
 360
 361         if (uctrl_msg->ctrl_msg_wire.magic != UDEV_CTRL_MAGIC) {
 362                 log_error("Message magic 0x%08x doesn't match, ignoring", uctrl_msg->ctrl_msg_wire.magic);
 363                 goto err;
 364         }
 365
 366         return uctrl_msg;
 367 err:
 368         udev_ctrl_msg_unref(uctrl_msg);
 369         return NULL;
 370 }
 371
 372 static struct udev_ctrl_msg *udev_ctrl_msg_free(struct udev_ctrl_msg *ctrl_msg) {
 373         assert(ctrl_msg);
 374
 375         udev_ctrl_connection_unref(ctrl_msg->conn);
 376         return mfree(ctrl_msg);
 377 }
 378
 379 DEFINE_TRIVIAL_UNREF_FUNC(struct udev_ctrl_msg, udev_ctrl_msg, udev_ctrl_msg_free);
 380
 381 int udev_ctrl_get_set_log_level(struct udev_ctrl_msg *ctrl_msg) {
 382         if (ctrl_msg->ctrl_msg_wire.type == UDEV_CTRL_SET_LOG_LEVEL)
 383                 return ctrl_msg->ctrl_msg_wire.intval;
 384         return -1;
 385 }
 386
 387 int udev_ctrl_get_stop_exec_queue(struct udev_ctrl_msg *ctrl_msg) {
 388         if (ctrl_msg->ctrl_msg_wire.type == UDEV_CTRL_STOP_EXEC_QUEUE)
 389                 return 1;
 390         return -1;
 391 }
 392
 393 int udev_ctrl_get_start_exec_queue(struct udev_ctrl_msg *ctrl_msg) {
 394         if (ctrl_msg->ctrl_msg_wire.type == UDEV_CTRL_START_EXEC_QUEUE)
 395                 return 1;
 396         return -1;
 397 }
 398
 399 int udev_ctrl_get_reload(struct udev_ctrl_msg *ctrl_msg) {
 400         if (ctrl_msg->ctrl_msg_wire.type == UDEV_CTRL_RELOAD)
 401                 return 1;
 402         return -1;
 403 }
 404
 405 const char *udev_ctrl_get_set_env(struct udev_ctrl_msg *ctrl_msg) {
 406         if (ctrl_msg->ctrl_msg_wire.type == UDEV_CTRL_SET_ENV)
 407                 return ctrl_msg->ctrl_msg_wire.buf;
 408         return NULL;
 409 }
 410
 411 int udev_ctrl_get_set_children_max(struct udev_ctrl_msg *ctrl_msg) {
 412         if (ctrl_msg->ctrl_msg_wire.type == UDEV_CTRL_SET_CHILDREN_MAX)
 413                 return ctrl_msg->ctrl_msg_wire.intval;
 414         return -1;
 415 }
 416
 417 int udev_ctrl_get_ping(struct udev_ctrl_msg *ctrl_msg) {
 418         if (ctrl_msg->ctrl_msg_wire.type == UDEV_CTRL_PING)
 419                 return 1;
 420         return -1;
 421 }
 422
 423 int udev_ctrl_get_exit(struct udev_ctrl_msg *ctrl_msg) {
 424         if (ctrl_msg->ctrl_msg_wire.type == UDEV_CTRL_EXIT)
 425                 return 1;
 426         return -1;
 427 }