src/socket-activate/socket-activate.c

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2
   3 #include <getopt.h>
   4 #include <sys/epoll.h>
   5 #include <sys/prctl.h>
   6 #include <sys/wait.h>
   7 #include <unistd.h>
   8
   9 #include "sd-daemon.h"
  10
  11 #include "alloc-util.h"
  12 #include "build.h"
  13 #include "env-util.h"
  14 #include "errno-util.h"
  15 #include "escape.h"
  16 #include "fd-util.h"
  17 #include "log.h"
  18 #include "macro.h"
  19 #include "main-func.h"
  20 #include "pretty-print.h"
  21 #include "process-util.h"
  22 #include "signal-util.h"
  23 #include "socket-netlink.h"
  24 #include "socket-util.h"
  25 #include "string-util.h"
  26 #include "strv.h"
  27 #include "terminal-util.h"
  28
  29 static char **arg_listen = NULL;
  30 static bool arg_accept = false;
  31 static int arg_socket_type = SOCK_STREAM;
  32 static char **arg_args = NULL;
  33 static char **arg_setenv = NULL;
  34 static char **arg_fdnames = NULL;
  35 static bool arg_inetd = false;
  36
  37 static int add_epoll(int epoll_fd, int fd) {
  38         struct epoll_event ev = {
  39                 .events = EPOLLIN,
  40                 .data.fd = fd,
  41         };
  42
  43         assert(epoll_fd >= 0);
  44         assert(fd >= 0);
  45
  46         if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, fd, &ev) < 0)
  47                 return log_error_errno(errno, "Failed to add event on epoll fd:%d for fd:%d: %m", epoll_fd, fd);
  48
  49         return 0;
  50 }
  51
  52 static int open_sockets(int *ret_epoll_fd, bool accept) {
  53         _cleanup_close_ int epoll_fd = -EBADF;
  54         int n, r, count = 0;
  55
  56         assert(ret_epoll_fd);
  57
  58         n = sd_listen_fds(true);
  59         if (n < 0)
  60                 return log_error_errno(n, "Failed to read listening file descriptors from environment: %m");
  61         if (n > 0) {
  62                 log_info("Received %i descriptors via the environment.", n);
  63
  64                 for (int fd = SD_LISTEN_FDS_START; fd < SD_LISTEN_FDS_START + n; fd++) {
  65                         r = fd_cloexec(fd, arg_accept);
  66                         if (r < 0)
  67                                 return r;
  68
  69                         count++;
  70                 }
  71         }
  72
  73         /* Close logging and all other descriptors */
  74         if (arg_listen) {
  75                 _cleanup_free_ int *except = new(int, n);
  76                 if (!except)
  77                         return log_oom();
  78
  79                 for (int i = 0; i < n; i++)
  80                         except[i] = SD_LISTEN_FDS_START + i;
  81
  82                 log_close();
  83                 log_set_open_when_needed(true);
  84                 log_settle_target();
  85
  86                 r = close_all_fds(except, n);
  87                 if (r < 0)
  88                         return log_error_errno(r, "Failed to close all file descriptors: %m");
  89         }
  90
  91         /* Note: we leak some fd's on error here. It doesn't matter much, since the program will exit
  92          * immediately anyway, but would be a pain to fix. */
  93
  94         STRV_FOREACH(address, arg_listen) {
  95                 r = make_socket_fd(LOG_DEBUG, *address, arg_socket_type, (arg_accept * SOCK_CLOEXEC));
  96                 if (r < 0)
  97                         return log_error_errno(r, "Failed to open '%s': %m", *address);
  98
  99                 assert(r == SD_LISTEN_FDS_START + count);
 100                 count++;
 101         }
 102
 103         if (arg_listen) {
 104                 log_open();
 105                 log_set_open_when_needed(false);
 106         }
 107
 108         epoll_fd = epoll_create1(EPOLL_CLOEXEC);
 109         if (epoll_fd < 0)
 110                 return log_error_errno(errno, "Failed to create epoll object: %m");
 111
 112         for (int fd = SD_LISTEN_FDS_START; fd < SD_LISTEN_FDS_START + count; fd++) {
 113                 _cleanup_free_ char *name = NULL;
 114
 115                 getsockname_pretty(fd, &name);
 116                 log_info("Listening on %s as %i.", strna(name), fd);
 117
 118                 r = add_epoll(epoll_fd, fd);
 119                 if (r < 0)
 120                         return r;
 121         }
 122
 123         *ret_epoll_fd = TAKE_FD(epoll_fd);
 124         return count;
 125 }
 126
 127 static int exec_process(const char *name, char **argv, int start_fd, size_t n_fds) {
 128         _cleanup_strv_free_ char **envp = NULL;
 129         int r;
 130
 131         if (arg_inetd && n_fds != 1)
 132                 return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
 133                                        "--inetd only supported for single file descriptors.");
 134
 135         FOREACH_STRING(var, "TERM", "PATH", "USER", "HOME") {
 136                 const char *n;
 137
 138                 n = strv_find_prefix(environ, var);
 139                 if (!n)
 140                         continue;
 141
 142                 r = strv_extend(&envp, n);
 143                 if (r < 0)
 144                         return r;
 145         }
 146
 147         if (arg_inetd) {
 148                 assert(n_fds == 1);
 149
 150                 r = rearrange_stdio(start_fd, start_fd, STDERR_FILENO); /* invalidates start_fd on success + error */
 151                 if (r < 0)
 152                         return log_error_errno(r, "Failed to move fd to stdin+stdout: %m");
 153
 154         } else {
 155                 if (start_fd != SD_LISTEN_FDS_START) {
 156                         assert(n_fds == 1);
 157
 158                         if (dup2(start_fd, SD_LISTEN_FDS_START) < 0)
 159                                 return log_error_errno(errno, "Failed to dup connection: %m");
 160
 161                         safe_close(start_fd);
 162                 }
 163
 164                 r = strv_extendf(&envp, "LISTEN_FDS=%zu", n_fds);
 165                 if (r < 0)
 166                         return r;
 167
 168                 r = strv_extendf(&envp, "LISTEN_PID=" PID_FMT, getpid_cached());
 169                 if (r < 0)
 170                         return r;
 171
 172                 if (arg_fdnames) {
 173                         _cleanup_free_ char *names = NULL;
 174                         size_t len;
 175
 176                         len = strv_length(arg_fdnames);
 177                         if (len == 1)
 178                                 for (size_t i = 1; i < n_fds; i++) {
 179                                         r = strv_extend(&arg_fdnames, arg_fdnames[0]);
 180                                         if (r < 0)
 181                                                 return log_oom();
 182                                 }
 183                         else if (len != n_fds)
 184                                 log_warning("The number of fd names is different than number of fds: %zu vs %zu", len, n_fds);
 185
 186                         names = strv_join(arg_fdnames, ":");
 187                         if (!names)
 188                                 return log_oom();
 189
 190                         char *t = strjoin("LISTEN_FDNAMES=", names);
 191                         if (!t)
 192                                 return log_oom();
 193
 194                         r = strv_consume(&envp, t);
 195                         if (r < 0)
 196                                 return r;
 197                 }
 198         }
 199
 200         STRV_FOREACH(s, arg_setenv) {
 201                 r = strv_env_replace_strdup(&envp, *s);
 202                 if (r < 0)
 203                         return r;
 204         }
 205
 206         _cleanup_free_ char *joined = strv_join(argv, " ");
 207         if (!joined)
 208                 return log_oom();
 209
 210         log_info("Execing %s (%s)", name, joined);
 211         execvpe(name, argv, envp);
 212
 213         return log_error_errno(errno, "Failed to execp %s (%s): %m", name, joined);
 214 }
 215
 216 static int fork_and_exec_process(const char *child, char **argv, int fd) {
 217         _cleanup_free_ char *joined = NULL;
 218         pid_t child_pid;
 219         int r;
 220
 221         joined = strv_join(argv, " ");
 222         if (!joined)
 223                 return log_oom();
 224
 225         r = safe_fork("(activate)",
 226                       FORK_RESET_SIGNALS | FORK_DEATHSIG_SIGTERM | FORK_RLIMIT_NOFILE_SAFE | FORK_LOG,
 227                       &child_pid);
 228         if (r < 0)
 229                 return r;
 230         if (r == 0) {
 231                 /* In the child */
 232                 exec_process(child, argv, fd, 1);
 233                 _exit(EXIT_FAILURE);
 234         }
 235
 236         log_info("Spawned %s (%s) as PID " PID_FMT ".", child, joined, child_pid);
 237         return 0;
 238 }
 239
 240 static int do_accept(const char *name, char **argv, int fd) {
 241         _cleanup_free_ char *local = NULL, *peer = NULL;
 242         _cleanup_close_ int fd_accepted = -EBADF;
 243
 244         fd_accepted = accept4(fd, NULL, NULL, 0);
 245         if (fd_accepted < 0) {
 246                 if (ERRNO_IS_ACCEPT_AGAIN(errno))
 247                         return 0;
 248
 249                 return log_error_errno(errno, "Failed to accept connection on fd:%d: %m", fd);
 250         }
 251
 252         (void) getsockname_pretty(fd_accepted, &local);
 253         (void) getpeername_pretty(fd_accepted, true, &peer);
 254         log_info("Connection from %s to %s", strna(peer), strna(local));
 255
 256         return fork_and_exec_process(name, argv, fd_accepted);
 257 }
 258
 259 /* SIGCHLD handler. */
 260 static void sigchld_hdl(int sig) {
 261         PROTECT_ERRNO;
 262
 263         for (;;) {
 264                 siginfo_t si;
 265                 int r;
 266
 267                 si.si_pid = 0;
 268                 r = waitid(P_ALL, 0, &si, WEXITED | WNOHANG);
 269                 if (r < 0) {
 270                         if (errno != ECHILD)
 271                                 log_error_errno(errno, "Failed to reap children: %m");
 272                         return;
 273                 }
 274                 if (si.si_pid == 0)
 275                         return;
 276
 277                 log_info("Child %d died with code %d", si.si_pid, si.si_status);
 278         }
 279 }
 280
 281 static int install_chld_handler(void) {
 282         static const struct sigaction act = {
 283                 .sa_flags = SA_NOCLDSTOP | SA_RESTART,
 284                 .sa_handler = sigchld_hdl,
 285         };
 286
 287         if (sigaction(SIGCHLD, &act, 0) < 0)
 288                 return log_error_errno(errno, "Failed to install SIGCHLD handler: %m");
 289
 290         return 0;
 291 }
 292
 293 static int help(void) {
 294         _cleanup_free_ char *link = NULL;
 295         int r;
 296
 297         r = terminal_urlify_man("systemd-socket-activate", "1", &link);
 298         if (r < 0)
 299                 return log_oom();
 300
 301         printf("%s [OPTIONS...]\n"
 302                "\n%sListen on sockets and launch child on connection.%s\n"
 303                "\nOptions:\n"
 304                "  -h --help                  Show this help and exit\n"
 305                "     --version               Print version string and exit\n"
 306                "  -l --listen=ADDR           Listen for raw connections at ADDR\n"
 307                "  -d --datagram              Listen on datagram instead of stream socket\n"
 308                "     --seqpacket             Listen on SOCK_SEQPACKET instead of stream socket\n"
 309                "  -a --accept                Spawn separate child for each connection\n"
 310                "  -E --setenv=NAME[=VALUE]   Pass an environment variable to children\n"
 311                "     --fdname=NAME[:NAME...] Specify names for file descriptors\n"
 312                "     --inetd                 Enable inetd file descriptor passing protocol\n"
 313                "\nNote: file descriptors from sd_listen_fds() will be passed through.\n"
 314                "\nSee the %s for details.\n",
 315                program_invocation_short_name,
 316                ansi_highlight(),
 317                ansi_normal(),
 318                link);
 319
 320         return 0;
 321 }
 322
 323 static int parse_argv(int argc, char *argv[]) {
 324         enum {
 325                 ARG_VERSION = 0x100,
 326                 ARG_FDNAME,
 327                 ARG_SEQPACKET,
 328                 ARG_INETD,
 329         };
 330
 331         static const struct option options[] = {
 332                 { "help",        no_argument,       NULL, 'h'           },
 333                 { "version",     no_argument,       NULL, ARG_VERSION   },
 334                 { "datagram",    no_argument,       NULL, 'd'           },
 335                 { "seqpacket",   no_argument,       NULL, ARG_SEQPACKET },
 336                 { "listen",      required_argument, NULL, 'l'           },
 337                 { "accept",      no_argument,       NULL, 'a'           },
 338                 { "setenv",      required_argument, NULL, 'E'           },
 339                 { "environment", required_argument, NULL, 'E'           }, /* legacy alias */
 340                 { "fdname",      required_argument, NULL, ARG_FDNAME    },
 341                 { "inetd",       no_argument,       NULL, ARG_INETD     },
 342                 {}
 343         };
 344
 345         int c, r;
 346
 347         assert(argc >= 0);
 348         assert(argv);
 349
 350         /* Resetting to 0 forces the invocation of an internal initialization routine of getopt_long()
 351          * that checks for GNU extensions in optstring ('-' or '+' at the beginning). */
 352         optind = 0;
 353         while ((c = getopt_long(argc, argv, "+hl:aE:d", options, NULL)) >= 0)
 354                 switch (c) {
 355                 case 'h':
 356                         return help();
 357
 358                 case ARG_VERSION:
 359                         return version();
 360
 361                 case 'l':
 362                         r = strv_extend(&arg_listen, optarg);
 363                         if (r < 0)
 364                                 return log_oom();
 365
 366                         break;
 367
 368                 case 'd':
 369                         if (arg_socket_type == SOCK_SEQPACKET)
 370                                 return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
 371                                                        "--datagram may not be combined with --seqpacket.");
 372
 373                         arg_socket_type = SOCK_DGRAM;
 374                         break;
 375
 376                 case ARG_SEQPACKET:
 377                         if (arg_socket_type == SOCK_DGRAM)
 378                                 return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
 379                                                        "--seqpacket may not be combined with --datagram.");
 380
 381                         arg_socket_type = SOCK_SEQPACKET;
 382                         break;
 383
 384                 case 'a':
 385                         arg_accept = true;
 386                         break;
 387
 388                 case 'E':
 389                         r = strv_env_replace_strdup_passthrough(&arg_setenv, optarg);
 390                         if (r < 0)
 391                                 return log_error_errno(r, "Cannot assign environment variable %s: %m", optarg);
 392                         break;
 393
 394                 case ARG_FDNAME: {
 395                         _cleanup_strv_free_ char **names = NULL;
 396
 397                         names = strv_split(optarg, ":");
 398                         if (!names)
 399                                 return log_oom();
 400
 401                         STRV_FOREACH(s, names)
 402                                 if (!fdname_is_valid(*s)) {
 403                                         _cleanup_free_ char *esc = NULL;
 404
 405                                         esc = cescape(*s);
 406                                         log_warning("File descriptor name \"%s\" is not valid.", esc);
 407                                 }
 408
 409                         /* Empty optargs means one empty name */
 410                         r = strv_extend_strv(&arg_fdnames,
 411                                              strv_isempty(names) ? STRV_MAKE("") : names,
 412                                              false);
 413                         if (r < 0)
 414                                 return log_error_errno(r, "strv_extend_strv: %m");
 415                         break;
 416                 }
 417
 418                 case ARG_INETD:
 419                         arg_inetd = true;
 420                         break;
 421
 422                 case '?':
 423                         return -EINVAL;
 424
 425                 default:
 426                         assert_not_reached();
 427                 }
 428
 429         if (optind == argc)
 430                 return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
 431                                        "%s: command to execute is missing.",
 432                                        program_invocation_short_name);
 433
 434         if (arg_socket_type == SOCK_DGRAM && arg_accept)
 435                 return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
 436                                        "Datagram sockets do not accept connections. "
 437                                        "The --datagram and --accept options may not be combined.");
 438
 439         arg_args = argv + optind;
 440
 441         return 1 /* work to do */;
 442 }
 443
 444 static int run(int argc, char **argv) {
 445         _cleanup_close_ int epoll_fd = -EBADF;
 446         _cleanup_strv_free_ char **exec_argv = NULL;
 447         int r, n;
 448
 449         log_show_color(true);
 450         log_parse_environment();
 451         log_open();
 452
 453         r = parse_argv(argc, argv);
 454         if (r <= 0)
 455                 return r;
 456
 457         exec_argv = strv_copy(arg_args);
 458         if (!exec_argv)
 459                 return log_oom();
 460
 461         assert(!strv_isempty(exec_argv));
 462
 463         r = install_chld_handler();
 464         if (r < 0)
 465                 return r;
 466
 467         n = open_sockets(&epoll_fd, arg_accept);
 468         if (n < 0)
 469                 return n;
 470         if (n == 0)
 471                 return log_error_errno(SYNTHETIC_ERRNO(ENOENT), "No sockets to listen on specified or passed in.");
 472
 473         for (;;) {
 474                 struct epoll_event event;
 475
 476                 if (epoll_wait(epoll_fd, &event, 1, -1) < 0) {
 477                         if (errno == EINTR)
 478                                 continue;
 479
 480                         return log_error_errno(errno, "epoll_wait() failed: %m");
 481                 }
 482
 483                 log_info("Communication attempt on fd %i.", event.data.fd);
 484                 if (arg_accept) {
 485                         r = do_accept(exec_argv[0], exec_argv, event.data.fd);
 486                         if (r < 0)
 487                                 return r;
 488                 } else
 489                         break;
 490         }
 491
 492         return exec_process(exec_argv[0], exec_argv, SD_LISTEN_FDS_START, (size_t) n);
 493 }
 494
 495 DEFINE_MAIN_FUNCTION(run);