src/activate/activate.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright 2013 Zbigniew Jędrzejewski-Szmek
   5
   6   systemd is free software; you can redistribute it and/or modify it
   7   under the terms of the GNU Lesser General Public License as published by
   8   the Free Software Foundation; either version 2.1 of the License, or
   9   (at your option) any later version.
  10
  11   systemd is distributed in the hope that it will be useful, but
  12   WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14   Lesser General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public License
  17   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  18 ***/
  19
  20 #include <getopt.h>
  21 #include <sys/epoll.h>
  22 #include <sys/prctl.h>
  23 #include <sys/socket.h>
  24 #include <sys/wait.h>
  25 #include <unistd.h>
  26
  27 #include "sd-daemon.h"
  28
  29 #include "alloc-util.h"
  30 #include "fd-util.h"
  31 #include "log.h"
  32 #include "macro.h"
  33 #include "signal-util.h"
  34 #include "socket-util.h"
  35 #include "string-util.h"
  36 #include "strv.h"
  37
  38 static char** arg_listen = NULL;
  39 static bool arg_accept = false;
  40 static int arg_socket_type = SOCK_STREAM;
  41 static char** arg_args = NULL;
  42 static char** arg_setenv = NULL;
  43 static const char *arg_fdname = NULL;
  44 static bool arg_inetd = false;
  45
  46 static int add_epoll(int epoll_fd, int fd) {
  47         struct epoll_event ev = {
  48                 .events = EPOLLIN
  49         };
  50         int r;
  51
  52         assert(epoll_fd >= 0);
  53         assert(fd >= 0);
  54
  55         ev.data.fd = fd;
  56         r = epoll_ctl(epoll_fd, EPOLL_CTL_ADD, fd, &ev);
  57         if (r < 0)
  58                 return log_error_errno(errno, "Failed to add event on epoll fd:%d for fd:%d: %m", epoll_fd, fd);
  59
  60         return 0;
  61 }
  62
  63 static int open_sockets(int *epoll_fd, bool accept) {
  64         char **address;
  65         int n, fd, r;
  66         int count = 0;
  67
  68         n = sd_listen_fds(true);
  69         if (n < 0)
  70                 return log_error_errno(n, "Failed to read listening file descriptors from environment: %m");
  71         if (n > 0) {
  72                 log_info("Received %i descriptors via the environment.", n);
  73
  74                 for (fd = SD_LISTEN_FDS_START; fd < SD_LISTEN_FDS_START + n; fd++) {
  75                         r = fd_cloexec(fd, arg_accept);
  76                         if (r < 0)
  77                                 return r;
  78
  79                         count ++;
  80                 }
  81         }
  82
  83         /* Close logging and all other descriptors */
  84         if (arg_listen) {
  85                 int except[3 + n];
  86
  87                 for (fd = 0; fd < SD_LISTEN_FDS_START + n; fd++)
  88                         except[fd] = fd;
  89
  90                 log_close();
  91                 close_all_fds(except, 3 + n);
  92         }
  93
  94         /** Note: we leak some fd's on error here. I doesn't matter
  95          *  much, since the program will exit immediately anyway, but
  96          *  would be a pain to fix.
  97          */
  98
  99         STRV_FOREACH(address, arg_listen) {
 100                 fd = make_socket_fd(LOG_DEBUG, *address, arg_socket_type, (arg_accept*SOCK_CLOEXEC));
 101                 if (fd < 0) {
 102                         log_open();
 103                         return log_error_errno(fd, "Failed to open '%s': %m", *address);
 104                 }
 105
 106                 assert(fd == SD_LISTEN_FDS_START + count);
 107                 count ++;
 108         }
 109
 110         if (arg_listen)
 111                 log_open();
 112
 113         *epoll_fd = epoll_create1(EPOLL_CLOEXEC);
 114         if (*epoll_fd < 0)
 115                 return log_error_errno(errno, "Failed to create epoll object: %m");
 116
 117         for (fd = SD_LISTEN_FDS_START; fd < SD_LISTEN_FDS_START + count; fd++) {
 118                 _cleanup_free_ char *name = NULL;
 119
 120                 getsockname_pretty(fd, &name);
 121                 log_info("Listening on %s as %i.", strna(name), fd);
 122
 123                 r = add_epoll(*epoll_fd, fd);
 124                 if (r < 0)
 125                         return r;
 126         }
 127
 128         return count;
 129 }
 130
 131 static int exec_process(const char* name, char **argv, char **env, int start_fd, int n_fds) {
 132
 133         _cleanup_strv_free_ char **envp = NULL;
 134         _cleanup_free_ char *joined = NULL;
 135         unsigned n_env = 0, length;
 136         const char *tocopy;
 137         unsigned i;
 138         char **s;
 139         int r;
 140
 141         if (arg_inetd && n_fds != 1) {
 142                 log_error("--inetd only supported for single file descriptors.");
 143                 return -EINVAL;
 144         }
 145
 146         length = strv_length(arg_setenv);
 147
 148         /* PATH, TERM, HOME, USER, LISTEN_FDS, LISTEN_PID, LISTEN_FDNAMES, NULL */
 149         envp = new0(char *, length + 8);
 150         if (!envp)
 151                 return log_oom();
 152
 153         STRV_FOREACH(s, arg_setenv) {
 154
 155                 if (strchr(*s, '=')) {
 156                         char *k;
 157
 158                         k = strdup(*s);
 159                         if (!k)
 160                                 return log_oom();
 161
 162                         envp[n_env++] = k;
 163                 } else {
 164                         _cleanup_free_ char *p;
 165                         const char *n;
 166
 167                         p = strappend(*s, "=");
 168                         if (!p)
 169                                 return log_oom();
 170
 171                         n = strv_find_prefix(env, p);
 172                         if (!n)
 173                                 continue;
 174
 175                         envp[n_env] = strdup(n);
 176                         if (!envp[n_env])
 177                                 return log_oom();
 178
 179                         n_env ++;
 180                 }
 181         }
 182
 183         FOREACH_STRING(tocopy, "TERM=", "PATH=", "USER=", "HOME=") {
 184                 const char *n;
 185
 186                 n = strv_find_prefix(env, tocopy);
 187                 if (!n)
 188                         continue;
 189
 190                 envp[n_env] = strdup(n);
 191                 if (!envp[n_env])
 192                         return log_oom();
 193
 194                 n_env ++;
 195         }
 196
 197         if (arg_inetd) {
 198                 assert(n_fds == 1);
 199
 200                 r = dup2(start_fd, STDIN_FILENO);
 201                 if (r < 0)
 202                         return log_error_errno(errno, "Failed to dup connection to stdin: %m");
 203
 204                 r = dup2(start_fd, STDOUT_FILENO);
 205                 if (r < 0)
 206                         return log_error_errno(errno, "Failed to dup connection to stdout: %m");
 207
 208                 start_fd = safe_close(start_fd);
 209         } else {
 210                 if (start_fd != SD_LISTEN_FDS_START) {
 211                         assert(n_fds == 1);
 212
 213                         r = dup2(start_fd, SD_LISTEN_FDS_START);
 214                         if (r < 0)
 215                                 return log_error_errno(errno, "Failed to dup connection: %m");
 216
 217                         safe_close(start_fd);
 218                         start_fd = SD_LISTEN_FDS_START;
 219                 }
 220
 221                 if (asprintf((char**)(envp + n_env++), "LISTEN_FDS=%i", n_fds) < 0)
 222                         return log_oom();
 223
 224                 if (asprintf((char**)(envp + n_env++), "LISTEN_PID=" PID_FMT, getpid()) < 0)
 225                         return log_oom();
 226
 227                 if (arg_fdname) {
 228                         char *e;
 229
 230                         e = strappend("LISTEN_FDNAMES=", arg_fdname);
 231                         if (!e)
 232                                 return log_oom();
 233
 234                         for (i = 1; i < (unsigned) n_fds; i++) {
 235                                 char *c;
 236
 237                                 c = strjoin(e, ":", arg_fdname, NULL);
 238                                 if (!c) {
 239                                         free(e);
 240                                         return log_oom();
 241                                 }
 242
 243                                 free(e);
 244                                 e = c;
 245                         }
 246
 247                         envp[n_env++] = e;
 248                 }
 249         }
 250
 251         joined = strv_join(argv, " ");
 252         if (!joined)
 253                 return log_oom();
 254
 255         log_info("Execing %s (%s)", name, joined);
 256         execvpe(name, argv, envp);
 257
 258         return log_error_errno(errno, "Failed to execp %s (%s): %m", name, joined);
 259 }
 260
 261 static int fork_and_exec_process(const char* child, char** argv, char **env, int fd) {
 262         _cleanup_free_ char *joined = NULL;
 263         pid_t parent_pid, child_pid;
 264
 265         joined = strv_join(argv, " ");
 266         if (!joined)
 267                 return log_oom();
 268
 269         parent_pid = getpid();
 270
 271         child_pid = fork();
 272         if (child_pid < 0)
 273                 return log_error_errno(errno, "Failed to fork: %m");
 274
 275         /* In the child */
 276         if (child_pid == 0) {
 277
 278                 (void) reset_all_signal_handlers();
 279                 (void) reset_signal_mask();
 280
 281                 /* Make sure the child goes away when the parent dies */
 282                 if (prctl(PR_SET_PDEATHSIG, SIGTERM) < 0)
 283                         _exit(EXIT_FAILURE);
 284
 285                 /* Check whether our parent died before we were able
 286                  * to set the death signal */
 287                 if (getppid() != parent_pid)
 288                         _exit(EXIT_SUCCESS);
 289
 290                 exec_process(child, argv, env, fd, 1);
 291                 _exit(EXIT_FAILURE);
 292         }
 293
 294         log_info("Spawned %s (%s) as PID %d", child, joined, child_pid);
 295         return 0;
 296 }
 297
 298 static int do_accept(const char* name, char **argv, char **envp, int fd) {
 299         _cleanup_free_ char *local = NULL, *peer = NULL;
 300         _cleanup_close_ int fd_accepted = -1;
 301
 302         fd_accepted = accept4(fd, NULL, NULL, 0);
 303         if (fd_accepted < 0)
 304                 return log_error_errno(errno, "Failed to accept connection on fd:%d: %m", fd);
 305
 306         getsockname_pretty(fd_accepted, &local);
 307         getpeername_pretty(fd_accepted, true, &peer);
 308         log_info("Connection from %s to %s", strna(peer), strna(local));
 309
 310         return fork_and_exec_process(name, argv, envp, fd_accepted);
 311 }
 312
 313 /* SIGCHLD handler. */
 314 static void sigchld_hdl(int sig, siginfo_t *t, void *data) {
 315         PROTECT_ERRNO;
 316
 317         log_info("Child %d died with code %d", t->si_pid, t->si_status);
 318
 319         /* Wait for a dead child. */
 320         (void) waitpid(t->si_pid, NULL, 0);
 321 }
 322
 323 static int install_chld_handler(void) {
 324         static const struct sigaction act = {
 325                 .sa_flags = SA_SIGINFO,
 326                 .sa_sigaction = sigchld_hdl,
 327         };
 328
 329         int r;
 330
 331         r = sigaction(SIGCHLD, &act, 0);
 332         if (r < 0)
 333                 return log_error_errno(errno, "Failed to install SIGCHLD handler: %m");
 334
 335         return 0;
 336 }
 337
 338 static void help(void) {
 339         printf("%s [OPTIONS...]\n\n"
 340                "Listen on sockets and launch child on connection.\n\n"
 341                "Options:\n"
 342                "  -h --help                Show this help and exit\n"
 343                "     --version             Print version string and exit\n"
 344                "  -l --listen=ADDR         Listen for raw connections at ADDR\n"
 345                "  -d --datagram            Listen on datagram instead of stream socket\n"
 346                "     --seqpacket           Listen on SOCK_SEQPACKET instead of stream socket\n"
 347                "  -a --accept              Spawn separate child for each connection\n"
 348                "  -E --setenv=NAME[=VALUE] Pass an environment variable to children\n"
 349                "     --inetd               Enable inetd file descriptor passing protocol\n"
 350                "\n"
 351                "Note: file descriptors from sd_listen_fds() will be passed through.\n"
 352                , program_invocation_short_name);
 353 }
 354
 355 static int parse_argv(int argc, char *argv[]) {
 356         enum {
 357                 ARG_VERSION = 0x100,
 358                 ARG_FDNAME,
 359                 ARG_SEQPACKET,
 360                 ARG_INETD,
 361         };
 362
 363         static const struct option options[] = {
 364                 { "help",        no_argument,       NULL, 'h'           },
 365                 { "version",     no_argument,       NULL, ARG_VERSION   },
 366                 { "datagram",    no_argument,       NULL, 'd'           },
 367                 { "seqpacket",   no_argument,       NULL, ARG_SEQPACKET },
 368                 { "listen",      required_argument, NULL, 'l'           },
 369                 { "accept",      no_argument,       NULL, 'a'           },
 370                 { "setenv",      required_argument, NULL, 'E'           },
 371                 { "environment", required_argument, NULL, 'E'           }, /* legacy alias */
 372                 { "fdname",      required_argument, NULL, ARG_FDNAME    },
 373                 { "inetd",       no_argument,       NULL, ARG_INETD     },
 374                 {}
 375         };
 376
 377         int c, r;
 378
 379         assert(argc >= 0);
 380         assert(argv);
 381
 382         while ((c = getopt_long(argc, argv, "+hl:aEd", options, NULL)) >= 0)
 383                 switch(c) {
 384                 case 'h':
 385                         help();
 386                         return 0;
 387
 388                 case ARG_VERSION:
 389                         return version();
 390
 391                 case 'l':
 392                         r = strv_extend(&arg_listen, optarg);
 393                         if (r < 0)
 394                                 return log_oom();
 395
 396                         break;
 397
 398                 case 'd':
 399                         if (arg_socket_type == SOCK_SEQPACKET) {
 400                                 log_error("--datagram may not be combined with --seqpacket.");
 401                                 return -EINVAL;
 402                         }
 403
 404                         arg_socket_type = SOCK_DGRAM;
 405                         break;
 406
 407                 case ARG_SEQPACKET:
 408                         if (arg_socket_type == SOCK_DGRAM) {
 409                                 log_error("--seqpacket may not be combined with --datagram.");
 410                                 return -EINVAL;
 411                         }
 412
 413                         arg_socket_type = SOCK_SEQPACKET;
 414                         break;
 415
 416                 case 'a':
 417                         arg_accept = true;
 418                         break;
 419
 420                 case 'E':
 421                         r = strv_extend(&arg_setenv, optarg);
 422                         if (r < 0)
 423                                 return log_oom();
 424
 425                         break;
 426
 427                 case ARG_FDNAME:
 428                         if (!fdname_is_valid(optarg)) {
 429                                 log_error("File descriptor name %s is not valid, refusing.", optarg);
 430                                 return -EINVAL;
 431                         }
 432
 433                         arg_fdname = optarg;
 434                         break;
 435
 436                 case ARG_INETD:
 437                         arg_inetd = true;
 438                         break;
 439
 440                 case '?':
 441                         return -EINVAL;
 442
 443                 default:
 444                         assert_not_reached("Unhandled option");
 445                 }
 446
 447         if (optind == argc) {
 448                 log_error("%s: command to execute is missing.",
 449                           program_invocation_short_name);
 450                 return -EINVAL;
 451         }
 452
 453         if (arg_socket_type == SOCK_DGRAM && arg_accept) {
 454                 log_error("Datagram sockets do not accept connections. "
 455                           "The --datagram and --accept options may not be combined.");
 456                 return -EINVAL;
 457         }
 458
 459         arg_args = argv + optind;
 460
 461         return 1 /* work to do */;
 462 }
 463
 464 int main(int argc, char **argv, char **envp) {
 465         int r, n;
 466         int epoll_fd = -1;
 467
 468         log_parse_environment();
 469         log_open();
 470
 471         r = parse_argv(argc, argv);
 472         if (r <= 0)
 473                 return r == 0 ? EXIT_SUCCESS : EXIT_FAILURE;
 474
 475         r = install_chld_handler();
 476         if (r < 0)
 477                 return EXIT_FAILURE;
 478
 479         n = open_sockets(&epoll_fd, arg_accept);
 480         if (n < 0)
 481                 return EXIT_FAILURE;
 482         if (n == 0) {
 483                 log_error("No sockets to listen on specified or passed in.");
 484                 return EXIT_FAILURE;
 485         }
 486
 487         for (;;) {
 488                 struct epoll_event event;
 489
 490                 r = epoll_wait(epoll_fd, &event, 1, -1);
 491                 if (r < 0) {
 492                         if (errno == EINTR)
 493                                 continue;
 494
 495                         log_error_errno(errno, "epoll_wait() failed: %m");
 496                         return EXIT_FAILURE;
 497                 }
 498
 499                 log_info("Communication attempt on fd %i.", event.data.fd);
 500                 if (arg_accept) {
 501                         r = do_accept(argv[optind], argv + optind, envp, event.data.fd);
 502                         if (r < 0)
 503                                 return EXIT_FAILURE;
 504                 } else
 505                         break;
 506         }
 507
 508         exec_process(argv[optind], argv + optind, envp, SD_LISTEN_FDS_START, n);
 509
 510         return EXIT_SUCCESS;
 511 }