src/activate/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 "env-util.h"
  13 #include "errno-util.h"
  14 #include "escape.h"
  15 #include "fd-util.h"
  16 #include "log.h"
  17 #include "macro.h"
  18 #include "pretty-print.h"
  19 #include "process-util.h"
  20 #include "signal-util.h"
  21 #include "socket-netlink.h"
  22 #include "socket-util.h"
  23 #include "string-util.h"
  24 #include "strv.h"
  25 #include "terminal-util.h"
  26 #include "util.h"
  27
  28 static char **arg_listen = NULL;
  29 static bool arg_accept = false;
  30 static int arg_socket_type = SOCK_STREAM;
  31 static char **arg_args = NULL;
  32 static char **arg_setenv = NULL;
  33 static char **arg_fdnames = NULL;
  34 static bool arg_inetd = false;
  35
  36 static int add_epoll(int epoll_fd, int fd) {
  37         struct epoll_event ev = {
  38                 .events = EPOLLIN,
  39                 .data.fd = fd,
  40         };
  41
  42         assert(epoll_fd >= 0);
  43         assert(fd >= 0);
  44
  45         if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, fd, &ev) < 0)
  46                 return log_error_errno(errno, "Failed to add event on epoll fd:%d for fd:%d: %m", epoll_fd, fd);
  47
  48         return 0;
  49 }
  50
  51 static int open_sockets(int *epoll_fd, bool accept) {
  52         char **address;
  53         int n, fd, r, count = 0;
  54
  55         n = sd_listen_fds(true);
  56         if (n < 0)
  57                 return log_error_errno(n, "Failed to read listening file descriptors from environment: %m");
  58         if (n > 0) {
  59                 log_info("Received %i descriptors via the environment.", n);
  60
  61                 for (fd = SD_LISTEN_FDS_START; fd < SD_LISTEN_FDS_START + n; fd++) {
  62                         r = fd_cloexec(fd, arg_accept);
  63                         if (r < 0)
  64                                 return r;
  65
  66                         count++;
  67                 }
  68         }
  69
  70         /* Close logging and all other descriptors */
  71         if (arg_listen) {
  72                 _cleanup_free_ int *except = NULL;
  73                 int i;
  74
  75                 except = new(int, n);
  76                 if (!except)
  77                         return log_oom();
  78
  79                 for (i = 0; i < n; i++)
  80                         except[i] = SD_LISTEN_FDS_START + i;
  81
  82                 log_close();
  83                 r = close_all_fds(except, n);
  84                 if (r < 0)
  85                         return log_error_errno(r, "Failed to close all file descriptors: %m");
  86         }
  87
  88         /** Note: we leak some fd's on error here. I doesn't matter
  89          *  much, since the program will exit immediately anyway, but
  90          *  would be a pain to fix.
  91          */
  92
  93         STRV_FOREACH(address, arg_listen) {
  94                 fd = make_socket_fd(LOG_DEBUG, *address, arg_socket_type, (arg_accept * SOCK_CLOEXEC));
  95                 if (fd < 0) {
  96                         log_open();
  97                         return log_error_errno(fd, "Failed to open '%s': %m", *address);
  98                 }
  99
 100                 assert(fd == SD_LISTEN_FDS_START + count);
 101                 count++;
 102         }
 103
 104         if (arg_listen)
 105                 log_open();
 106
 107         *epoll_fd = epoll_create1(EPOLL_CLOEXEC);
 108         if (*epoll_fd < 0)
 109                 return log_error_errno(errno, "Failed to create epoll object: %m");
 110
 111         for (fd = SD_LISTEN_FDS_START; fd < SD_LISTEN_FDS_START + count; fd++) {
 112                 _cleanup_free_ char *name = NULL;
 113
 114                 getsockname_pretty(fd, &name);
 115                 log_info("Listening on %s as %i.", strna(name), fd);
 116
 117                 r = add_epoll(*epoll_fd, fd);
 118                 if (r < 0)
 119                         return r;
 120         }
 121
 122         return count;
 123 }
 124
 125 static int exec_process(const char *name, char **argv, int start_fd, size_t n_fds) {
 126         _cleanup_strv_free_ char **envp = NULL;
 127         const char *var;
 128         char **s;
 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 | 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 = -1;
 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         while ((c = getopt_long(argc, argv, "+hl:aE:d", options, NULL)) >= 0)
 351                 switch (c) {
 352                 case 'h':
 353                         return help();
 354
 355                 case ARG_VERSION:
 356                         return version();
 357
 358                 case 'l':
 359                         r = strv_extend(&arg_listen, optarg);
 360                         if (r < 0)
 361                                 return log_oom();
 362
 363                         break;
 364
 365                 case 'd':
 366                         if (arg_socket_type == SOCK_SEQPACKET)
 367                                 return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
 368                                                        "--datagram may not be combined with --seqpacket.");
 369
 370                         arg_socket_type = SOCK_DGRAM;
 371                         break;
 372
 373                 case ARG_SEQPACKET:
 374                         if (arg_socket_type == SOCK_DGRAM)
 375                                 return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
 376                                                        "--seqpacket may not be combined with --datagram.");
 377
 378                         arg_socket_type = SOCK_SEQPACKET;
 379                         break;
 380
 381                 case 'a':
 382                         arg_accept = true;
 383                         break;
 384
 385                 case 'E':
 386                         r = strv_env_replace_strdup_passthrough(&arg_setenv, optarg);
 387                         if (r < 0)
 388                                 return log_error_errno(r, "Cannot assign environment variable %s: %m", optarg);
 389                         break;
 390
 391                 case ARG_FDNAME: {
 392                         _cleanup_strv_free_ char **names = NULL;
 393                         char **s;
 394
 395                         names = strv_split(optarg, ":");
 396                         if (!names)
 397                                 return log_oom();
 398
 399                         STRV_FOREACH(s, names)
 400                                 if (!fdname_is_valid(*s)) {
 401                                         _cleanup_free_ char *esc = NULL;
 402
 403                                         esc = cescape(*s);
 404                                         log_warning("File descriptor name \"%s\" is not valid.", esc);
 405                                 }
 406
 407                         /* Empty optargs means one empty name */
 408                         r = strv_extend_strv(&arg_fdnames,
 409                                              strv_isempty(names) ? STRV_MAKE("") : names,
 410                                              false);
 411                         if (r < 0)
 412                                 return log_error_errno(r, "strv_extend_strv: %m");
 413                         break;
 414                 }
 415
 416                 case ARG_INETD:
 417                         arg_inetd = true;
 418                         break;
 419
 420                 case '?':
 421                         return -EINVAL;
 422
 423                 default:
 424                         assert_not_reached();
 425                 }
 426
 427         if (optind == argc)
 428                 return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
 429                                        "%s: command to execute is missing.",
 430                                        program_invocation_short_name);
 431
 432         if (arg_socket_type == SOCK_DGRAM && arg_accept)
 433                 return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
 434                                        "Datagram sockets do not accept connections. "
 435                                        "The --datagram and --accept options may not be combined.");
 436
 437         arg_args = argv + optind;
 438
 439         return 1 /* work to do */;
 440 }
 441
 442 int main(int argc, char **argv) {
 443         int r, n;
 444         int epoll_fd = -1;
 445
 446         log_show_color(true);
 447         log_parse_environment();
 448         log_open();
 449
 450         r = parse_argv(argc, argv);
 451         if (r <= 0)
 452                 return r == 0 ? EXIT_SUCCESS : EXIT_FAILURE;
 453
 454         r = install_chld_handler();
 455         if (r < 0)
 456                 return EXIT_FAILURE;
 457
 458         n = open_sockets(&epoll_fd, arg_accept);
 459         if (n < 0)
 460                 return EXIT_FAILURE;
 461         if (n == 0) {
 462                 log_error("No sockets to listen on specified or passed in.");
 463                 return EXIT_FAILURE;
 464         }
 465
 466         for (;;) {
 467                 struct epoll_event event;
 468
 469                 if (epoll_wait(epoll_fd, &event, 1, -1) < 0) {
 470                         if (errno == EINTR)
 471                                 continue;
 472
 473                         log_error_errno(errno, "epoll_wait() failed: %m");
 474                         return EXIT_FAILURE;
 475                 }
 476
 477                 log_info("Communication attempt on fd %i.", event.data.fd);
 478                 if (arg_accept) {
 479                         r = do_accept(argv[optind], argv + optind, event.data.fd);
 480                         if (r < 0)
 481                                 return EXIT_FAILURE;
 482                 } else
 483                         break;
 484         }
 485
 486         exec_process(argv[optind], argv + optind, SD_LISTEN_FDS_START, (size_t) n);
 487
 488         return EXIT_SUCCESS;
 489 }