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 "escape.h"
  31 #include "fd-util.h"
  32 #include "log.h"
  33 #include "macro.h"
  34 #include "signal-util.h"
  35 #include "socket-util.h"
  36 #include "string-util.h"
  37 #include "strv.h"
  38
  39 static char** arg_listen = NULL;
  40 static bool arg_accept = false;
  41 static int arg_socket_type = SOCK_STREAM;
  42 static char** arg_args = NULL;
  43 static char** arg_setenv = NULL;
  44 static char **arg_fdnames = NULL;
  45 static bool arg_inetd = false;
  46
  47 static int add_epoll(int epoll_fd, int fd) {
  48         struct epoll_event ev = {
  49                 .events = EPOLLIN
  50         };
  51         int r;
  52
  53         assert(epoll_fd >= 0);
  54         assert(fd >= 0);
  55
  56         ev.data.fd = fd;
  57         r = epoll_ctl(epoll_fd, EPOLL_CTL_ADD, fd, &ev);
  58         if (r < 0)
  59                 return log_error_errno(errno, "Failed to add event on epoll fd:%d for fd:%d: %m", epoll_fd, fd);
  60
  61         return 0;
  62 }
  63
  64 static int open_sockets(int *epoll_fd, bool accept) {
  65         char **address;
  66         int n, fd, r;
  67         int count = 0;
  68
  69         n = sd_listen_fds(true);
  70         if (n < 0)
  71                 return log_error_errno(n, "Failed to read listening file descriptors from environment: %m");
  72         if (n > 0) {
  73                 log_info("Received %i descriptors via the environment.", n);
  74
  75                 for (fd = SD_LISTEN_FDS_START; fd < SD_LISTEN_FDS_START + n; fd++) {
  76                         r = fd_cloexec(fd, arg_accept);
  77                         if (r < 0)
  78                                 return r;
  79
  80                         count++;
  81                 }
  82         }
  83
  84         /* Close logging and all other descriptors */
  85         if (arg_listen) {
  86                 int except[3 + n];
  87
  88                 for (fd = 0; fd < SD_LISTEN_FDS_START + n; fd++)
  89                         except[fd] = fd;
  90
  91                 log_close();
  92                 close_all_fds(except, 3 + n);
  93         }
  94
  95         /** Note: we leak some fd's on error here. I doesn't matter
  96          *  much, since the program will exit immediately anyway, but
  97          *  would be a pain to fix.
  98          */
  99
 100         STRV_FOREACH(address, arg_listen) {
 101                 fd = make_socket_fd(LOG_DEBUG, *address, arg_socket_type, (arg_accept*SOCK_CLOEXEC));
 102                 if (fd < 0) {
 103                         log_open();
 104                         return log_error_errno(fd, "Failed to open '%s': %m", *address);
 105                 }
 106
 107                 assert(fd == SD_LISTEN_FDS_START + count);
 108                 count++;
 109         }
 110
 111         if (arg_listen)
 112                 log_open();
 113
 114         *epoll_fd = epoll_create1(EPOLL_CLOEXEC);
 115         if (*epoll_fd < 0)
 116                 return log_error_errno(errno, "Failed to create epoll object: %m");
 117
 118         for (fd = SD_LISTEN_FDS_START; fd < SD_LISTEN_FDS_START + count; fd++) {
 119                 _cleanup_free_ char *name = NULL;
 120
 121                 getsockname_pretty(fd, &name);
 122                 log_info("Listening on %s as %i.", strna(name), fd);
 123
 124                 r = add_epoll(*epoll_fd, fd);
 125                 if (r < 0)
 126                         return r;
 127         }
 128
 129         return count;
 130 }
 131
 132 static int exec_process(const char* name, char **argv, char **env, int start_fd, int n_fds) {
 133
 134         _cleanup_strv_free_ char **envp = NULL;
 135         _cleanup_free_ char *joined = NULL;
 136         unsigned n_env = 0, length;
 137         const char *tocopy;
 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_fdnames) {
 228                         _cleanup_free_ char *names = NULL;
 229                         size_t len;
 230                         char *e;
 231                         int i;
 232
 233                         len = strv_length(arg_fdnames);
 234                         if (len == 1)
 235                                 for (i = 1; i < n_fds; i++) {
 236                                         r = strv_extend(&arg_fdnames, arg_fdnames[0]);
 237                                         if (r < 0)
 238                                                 return log_error_errno(r, "Failed to extend strv: %m");
 239                                 }
 240                         else if (len != (unsigned) n_fds)
 241                                 log_warning("The number of fd names is different than number of fds: %zu vs %d",
 242                                             len, n_fds);
 243
 244                         names = strv_join(arg_fdnames, ":");
 245                         if (!names)
 246                                 return log_oom();
 247
 248                         e = strappend("LISTEN_FDNAMES=", names);
 249                         if (!e)
 250                                 return log_oom();
 251
 252                         envp[n_env++] = e;
 253                 }
 254         }
 255
 256         joined = strv_join(argv, " ");
 257         if (!joined)
 258                 return log_oom();
 259
 260         log_info("Execing %s (%s)", name, joined);
 261         execvpe(name, argv, envp);
 262
 263         return log_error_errno(errno, "Failed to execp %s (%s): %m", name, joined);
 264 }
 265
 266 static int fork_and_exec_process(const char* child, char** argv, char **env, int fd) {
 267         _cleanup_free_ char *joined = NULL;
 268         pid_t parent_pid, child_pid;
 269
 270         joined = strv_join(argv, " ");
 271         if (!joined)
 272                 return log_oom();
 273
 274         parent_pid = getpid();
 275
 276         child_pid = fork();
 277         if (child_pid < 0)
 278                 return log_error_errno(errno, "Failed to fork: %m");
 279
 280         /* In the child */
 281         if (child_pid == 0) {
 282
 283                 (void) reset_all_signal_handlers();
 284                 (void) reset_signal_mask();
 285
 286                 /* Make sure the child goes away when the parent dies */
 287                 if (prctl(PR_SET_PDEATHSIG, SIGTERM) < 0)
 288                         _exit(EXIT_FAILURE);
 289
 290                 /* Check whether our parent died before we were able
 291                  * to set the death signal */
 292                 if (getppid() != parent_pid)
 293                         _exit(EXIT_SUCCESS);
 294
 295                 exec_process(child, argv, env, fd, 1);
 296                 _exit(EXIT_FAILURE);
 297         }
 298
 299         log_info("Spawned %s (%s) as PID %d", child, joined, child_pid);
 300         return 0;
 301 }
 302
 303 static int do_accept(const char* name, char **argv, char **envp, int fd) {
 304         _cleanup_free_ char *local = NULL, *peer = NULL;
 305         _cleanup_close_ int fd_accepted = -1;
 306
 307         fd_accepted = accept4(fd, NULL, NULL, 0);
 308         if (fd_accepted < 0)
 309                 return log_error_errno(errno, "Failed to accept connection on fd:%d: %m", fd);
 310
 311         getsockname_pretty(fd_accepted, &local);
 312         getpeername_pretty(fd_accepted, true, &peer);
 313         log_info("Connection from %s to %s", strna(peer), strna(local));
 314
 315         return fork_and_exec_process(name, argv, envp, fd_accepted);
 316 }
 317
 318 /* SIGCHLD handler. */
 319 static void sigchld_hdl(int sig, siginfo_t *t, void *data) {
 320         PROTECT_ERRNO;
 321
 322         log_info("Child %d died with code %d", t->si_pid, t->si_status);
 323
 324         /* Wait for a dead child. */
 325         (void) waitpid(t->si_pid, NULL, 0);
 326 }
 327
 328 static int install_chld_handler(void) {
 329         static const struct sigaction act = {
 330                 .sa_flags = SA_SIGINFO,
 331                 .sa_sigaction = sigchld_hdl,
 332         };
 333
 334         int r;
 335
 336         r = sigaction(SIGCHLD, &act, 0);
 337         if (r < 0)
 338                 return log_error_errno(errno, "Failed to install SIGCHLD handler: %m");
 339
 340         return 0;
 341 }
 342
 343 static void help(void) {
 344         printf("%s [OPTIONS...]\n\n"
 345                "Listen on sockets and launch child on connection.\n\n"
 346                "Options:\n"
 347                "  -h --help                  Show this help and exit\n"
 348                "     --version               Print version string and exit\n"
 349                "  -l --listen=ADDR           Listen for raw connections at ADDR\n"
 350                "  -d --datagram              Listen on datagram instead of stream socket\n"
 351                "     --seqpacket             Listen on SOCK_SEQPACKET instead of stream socket\n"
 352                "  -a --accept                Spawn separate child for each connection\n"
 353                "  -E --setenv=NAME[=VALUE]   Pass an environment variable to children\n"
 354                "     --fdname=NAME[:NAME...] Specify names for file descriptors\n"
 355                "     --inetd                 Enable inetd file descriptor passing protocol\n"
 356                "\n"
 357                "Note: file descriptors from sd_listen_fds() will be passed through.\n"
 358                , program_invocation_short_name);
 359 }
 360
 361 static int parse_argv(int argc, char *argv[]) {
 362         enum {
 363                 ARG_VERSION = 0x100,
 364                 ARG_FDNAME,
 365                 ARG_SEQPACKET,
 366                 ARG_INETD,
 367         };
 368
 369         static const struct option options[] = {
 370                 { "help",        no_argument,       NULL, 'h'           },
 371                 { "version",     no_argument,       NULL, ARG_VERSION   },
 372                 { "datagram",    no_argument,       NULL, 'd'           },
 373                 { "seqpacket",   no_argument,       NULL, ARG_SEQPACKET },
 374                 { "listen",      required_argument, NULL, 'l'           },
 375                 { "accept",      no_argument,       NULL, 'a'           },
 376                 { "setenv",      required_argument, NULL, 'E'           },
 377                 { "environment", required_argument, NULL, 'E'           }, /* legacy alias */
 378                 { "fdname",      required_argument, NULL, ARG_FDNAME    },
 379                 { "inetd",       no_argument,       NULL, ARG_INETD     },
 380                 {}
 381         };
 382
 383         int c, r;
 384
 385         assert(argc >= 0);
 386         assert(argv);
 387
 388         while ((c = getopt_long(argc, argv, "+hl:aE:d", options, NULL)) >= 0)
 389                 switch(c) {
 390                 case 'h':
 391                         help();
 392                         return 0;
 393
 394                 case ARG_VERSION:
 395                         return version();
 396
 397                 case 'l':
 398                         r = strv_extend(&arg_listen, optarg);
 399                         if (r < 0)
 400                                 return log_oom();
 401
 402                         break;
 403
 404                 case 'd':
 405                         if (arg_socket_type == SOCK_SEQPACKET) {
 406                                 log_error("--datagram may not be combined with --seqpacket.");
 407                                 return -EINVAL;
 408                         }
 409
 410                         arg_socket_type = SOCK_DGRAM;
 411                         break;
 412
 413                 case ARG_SEQPACKET:
 414                         if (arg_socket_type == SOCK_DGRAM) {
 415                                 log_error("--seqpacket may not be combined with --datagram.");
 416                                 return -EINVAL;
 417                         }
 418
 419                         arg_socket_type = SOCK_SEQPACKET;
 420                         break;
 421
 422                 case 'a':
 423                         arg_accept = true;
 424                         break;
 425
 426                 case 'E':
 427                         r = strv_extend(&arg_setenv, optarg);
 428                         if (r < 0)
 429                                 return log_oom();
 430
 431                         break;
 432
 433                 case ARG_FDNAME: {
 434                         _cleanup_strv_free_ char **names;
 435                         char **s;
 436
 437                         names = strv_split(optarg, ":");
 438                         if (!names)
 439                                 return log_oom();
 440
 441                         STRV_FOREACH(s, names)
 442                                 if (!fdname_is_valid(*s)) {
 443                                         _cleanup_free_ char *esc;
 444
 445                                         esc = cescape(*s);
 446                                         log_warning("File descriptor name \"%s\" is not valid.", esc);
 447                                 }
 448
 449                         /* Empty optargs means one empty name */
 450                         r = strv_extend_strv(&arg_fdnames,
 451                                              strv_isempty(names) ? STRV_MAKE("") : names,
 452                                              false);
 453                         if (r < 0)
 454                                 return log_error_errno(r, "strv_extend_strv: %m");
 455                         break;
 456                 }
 457
 458                 case ARG_INETD:
 459                         arg_inetd = true;
 460                         break;
 461
 462                 case '?':
 463                         return -EINVAL;
 464
 465                 default:
 466                         assert_not_reached("Unhandled option");
 467                 }
 468
 469         if (optind == argc) {
 470                 log_error("%s: command to execute is missing.",
 471                           program_invocation_short_name);
 472                 return -EINVAL;
 473         }
 474
 475         if (arg_socket_type == SOCK_DGRAM && arg_accept) {
 476                 log_error("Datagram sockets do not accept connections. "
 477                           "The --datagram and --accept options may not be combined.");
 478                 return -EINVAL;
 479         }
 480
 481         arg_args = argv + optind;
 482
 483         return 1 /* work to do */;
 484 }
 485
 486 int main(int argc, char **argv, char **envp) {
 487         int r, n;
 488         int epoll_fd = -1;
 489
 490         log_parse_environment();
 491         log_open();
 492
 493         r = parse_argv(argc, argv);
 494         if (r <= 0)
 495                 return r == 0 ? EXIT_SUCCESS : EXIT_FAILURE;
 496
 497         r = install_chld_handler();
 498         if (r < 0)
 499                 return EXIT_FAILURE;
 500
 501         n = open_sockets(&epoll_fd, arg_accept);
 502         if (n < 0)
 503                 return EXIT_FAILURE;
 504         if (n == 0) {
 505                 log_error("No sockets to listen on specified or passed in.");
 506                 return EXIT_FAILURE;
 507         }
 508
 509         for (;;) {
 510                 struct epoll_event event;
 511
 512                 r = epoll_wait(epoll_fd, &event, 1, -1);
 513                 if (r < 0) {
 514                         if (errno == EINTR)
 515                                 continue;
 516
 517                         log_error_errno(errno, "epoll_wait() failed: %m");
 518                         return EXIT_FAILURE;
 519                 }
 520
 521                 log_info("Communication attempt on fd %i.", event.data.fd);
 522                 if (arg_accept) {
 523                         r = do_accept(argv[optind], argv + optind, envp, event.data.fd);
 524                         if (r < 0)
 525                                 return EXIT_FAILURE;
 526                 } else
 527                         break;
 528         }
 529
 530         exec_process(argv[optind], argv + optind, envp, SD_LISTEN_FDS_START, n);
 531
 532         return EXIT_SUCCESS;
 533 }