daemon.c

   1 #include <signal.h>
   2 #include <sys/wait.h>
   3 #include <sys/socket.h>
   4 #include <sys/time.h>
   5 #include <sys/poll.h>
   6 #include <netdb.h>
   7 #include <netinet/in.h>
   8 #include <arpa/inet.h>
   9 #include <syslog.h>
  10 #include <pwd.h>
  11 #include <grp.h>
  12 #include "pkt-line.h"
  13 #include "cache.h"
  14 #include "exec_cmd.h"
  15
  16 static int log_syslog;
  17 static int verbose;
  18 static int reuseaddr;
  19
  20 static const char daemon_usage[] =
  21 "git-daemon [--verbose] [--syslog] [--inetd | --port=n] [--export-all]\n"
  22 "           [--timeout=n] [--init-timeout=n] [--strict-paths]\n"
  23 "           [--base-path=path] [--user-path | --user-path=path]\n"
  24 "           [--reuseaddr] [--detach] [--pid-file=file]\n"
  25 "           [--user=user [[--group=group]] [directory...]";
  26
  27 /* List of acceptable pathname prefixes */
  28 static char **ok_paths;
  29 static int strict_paths;
  30
  31 /* If this is set, git-daemon-export-ok is not required */
  32 static int export_all_trees;
  33
  34 /* Take all paths relative to this one if non-NULL */
  35 static char *base_path;
  36
  37 /* If defined, ~user notation is allowed and the string is inserted
  38  * after ~user/.  E.g. a request to git://host/~alice/frotz would
  39  * go to /home/alice/pub_git/frotz with --user-path=pub_git.
  40  */
  41 static const char *user_path;
  42
  43 /* Timeout, and initial timeout */
  44 static unsigned int timeout;
  45 static unsigned int init_timeout;
  46
  47 static void logreport(int priority, const char *err, va_list params)
  48 {
  49         /* We should do a single write so that it is atomic and output
  50          * of several processes do not get intermingled. */
  51         char buf[1024];
  52         int buflen;
  53         int maxlen, msglen;
  54
  55         /* sizeof(buf) should be big enough for "[pid] \n" */
  56         buflen = snprintf(buf, sizeof(buf), "[%ld] ", (long) getpid());
  57
  58         maxlen = sizeof(buf) - buflen - 1; /* -1 for our own LF */
  59         msglen = vsnprintf(buf + buflen, maxlen, err, params);
  60
  61         if (log_syslog) {
  62                 syslog(priority, "%s", buf);
  63                 return;
  64         }
  65
  66         /* maxlen counted our own LF but also counts space given to
  67          * vsnprintf for the terminating NUL.  We want to make sure that
  68          * we have space for our own LF and NUL after the "meat" of the
  69          * message, so truncate it at maxlen - 1.
  70          */
  71         if (msglen > maxlen - 1)
  72                 msglen = maxlen - 1;
  73         else if (msglen < 0)
  74                 msglen = 0; /* Protect against weird return values. */
  75         buflen += msglen;
  76
  77         buf[buflen++] = '\n';
  78         buf[buflen] = '\0';
  79
  80         write(2, buf, buflen);
  81 }
  82
  83 static void logerror(const char *err, ...)
  84 {
  85         va_list params;
  86         va_start(params, err);
  87         logreport(LOG_ERR, err, params);
  88         va_end(params);
  89 }
  90
  91 static void loginfo(const char *err, ...)
  92 {
  93         va_list params;
  94         if (!verbose)
  95                 return;
  96         va_start(params, err);
  97         logreport(LOG_INFO, err, params);
  98         va_end(params);
  99 }
 100
 101 static void NORETURN daemon_die(const char *err, va_list params)
 102 {
 103         logreport(LOG_ERR, err, params);
 104         exit(1);
 105 }
 106
 107 static int avoid_alias(char *p)
 108 {
 109         int sl, ndot;
 110
 111         /*
 112          * This resurrects the belts and suspenders paranoia check by HPA
 113          * done in <435560F7.4080006@zytor.com> thread, now enter_repo()
 114          * does not do getcwd() based path canonicalizations.
 115          *
 116          * sl becomes true immediately after seeing '/' and continues to
 117          * be true as long as dots continue after that without intervening
 118          * non-dot character.
 119          */
 120         if (!p || (*p != '/' && *p != '~'))
 121                 return -1;
 122         sl = 1; ndot = 0;
 123         p++;
 124
 125         while (1) {
 126                 char ch = *p++;
 127                 if (sl) {
 128                         if (ch == '.')
 129                                 ndot++;
 130                         else if (ch == '/') {
 131                                 if (ndot < 3)
 132                                         /* reject //, /./ and /../ */
 133                                         return -1;
 134                                 ndot = 0;
 135                         }
 136                         else if (ch == 0) {
 137                                 if (0 < ndot && ndot < 3)
 138                                         /* reject /.$ and /..$ */
 139                                         return -1;
 140                                 return 0;
 141                         }
 142                         else
 143                                 sl = ndot = 0;
 144                 }
 145                 else if (ch == 0)
 146                         return 0;
 147                 else if (ch == '/') {
 148                         sl = 1;
 149                         ndot = 0;
 150                 }
 151         }
 152 }
 153
 154 static char *path_ok(char *dir)
 155 {
 156         static char rpath[PATH_MAX];
 157         char *path;
 158
 159         if (avoid_alias(dir)) {
 160                 logerror("'%s': aliased", dir);
 161                 return NULL;
 162         }
 163
 164         if (*dir == '~') {
 165                 if (!user_path) {
 166                         logerror("'%s': User-path not allowed", dir);
 167                         return NULL;
 168                 }
 169                 if (*user_path) {
 170                         /* Got either "~alice" or "~alice/foo";
 171                          * rewrite them to "~alice/%s" or
 172                          * "~alice/%s/foo".
 173                          */
 174                         int namlen, restlen = strlen(dir);
 175                         char *slash = strchr(dir, '/');
 176                         if (!slash)
 177                                 slash = dir + restlen;
 178                         namlen = slash - dir;
 179                         restlen -= namlen;
 180                         loginfo("userpath <%s>, request <%s>, namlen %d, restlen %d, slash <%s>", user_path, dir, namlen, restlen, slash);
 181                         snprintf(rpath, PATH_MAX, "%.*s/%s%.*s",
 182                                  namlen, dir, user_path, restlen, slash);
 183                         dir = rpath;
 184                 }
 185         }
 186         else if (base_path) {
 187                 if (*dir != '/') {
 188                         /* Allow only absolute */
 189                         logerror("'%s': Non-absolute path denied (base-path active)", dir);
 190                         return NULL;
 191                 }
 192                 else {
 193                         snprintf(rpath, PATH_MAX, "%s%s", base_path, dir);
 194                         dir = rpath;
 195                 }
 196         }
 197
 198         path = enter_repo(dir, strict_paths);
 199
 200         if (!path) {
 201                 logerror("'%s': unable to chdir or not a git archive", dir);
 202                 return NULL;
 203         }
 204
 205         if ( ok_paths && *ok_paths ) {
 206                 char **pp;
 207                 int pathlen = strlen(path);
 208
 209                 /* The validation is done on the paths after enter_repo
 210                  * appends optional {.git,.git/.git} and friends, but
 211                  * it does not use getcwd().  So if your /pub is
 212                  * a symlink to /mnt/pub, you can whitelist /pub and
 213                  * do not have to say /mnt/pub.
 214                  * Do not say /pub/.
 215                  */
 216                 for ( pp = ok_paths ; *pp ; pp++ ) {
 217                         int len = strlen(*pp);
 218                         if (len <= pathlen &&
 219                             !memcmp(*pp, path, len) &&
 220                             (path[len] == '\0' ||
 221                              (!strict_paths && path[len] == '/')))
 222                                 return path;
 223                 }
 224         }
 225         else {
 226                 /* be backwards compatible */
 227                 if (!strict_paths)
 228                         return path;
 229         }
 230
 231         logerror("'%s': not in whitelist", path);
 232         return NULL;            /* Fallthrough. Deny by default */
 233 }
 234
 235 typedef int (*daemon_service_fn)(void);
 236 struct daemon_service {
 237         const char *name;
 238         const char *config_name;
 239         daemon_service_fn fn;
 240         int enabled;
 241         int overridable;
 242 };
 243
 244 static struct daemon_service *service_looking_at;
 245 static int service_enabled;
 246
 247 static int git_daemon_config(const char *var, const char *value)
 248 {
 249         if (!strncmp(var, "daemon.", 7) &&
 250             !strcmp(var + 7, service_looking_at->config_name)) {
 251                 service_enabled = git_config_bool(var, value);
 252                 return 0;
 253         }
 254
 255         /* we are not interested in parsing any other configuration here */
 256         return 0;
 257 }
 258
 259 static int run_service(char *dir, struct daemon_service *service)
 260 {
 261         const char *path;
 262         int enabled = service->enabled;
 263
 264         loginfo("Request %s for '%s'", service->name, dir);
 265
 266         if (!enabled && !service->overridable) {
 267                 logerror("'%s': service not enabled.", service->name);
 268                 errno = EACCES;
 269                 return -1;
 270         }
 271
 272         if (!(path = path_ok(dir)))
 273                 return -1;
 274
 275         /*
 276          * Security on the cheap.
 277          *
 278          * We want a readable HEAD, usable "objects" directory, and
 279          * a "git-daemon-export-ok" flag that says that the other side
 280          * is ok with us doing this.
 281          *
 282          * path_ok() uses enter_repo() and does whitelist checking.
 283          * We only need to make sure the repository is exported.
 284          */
 285
 286         if (!export_all_trees && access("git-daemon-export-ok", F_OK)) {
 287                 logerror("'%s': repository not exported.", path);
 288                 errno = EACCES;
 289                 return -1;
 290         }
 291
 292         if (service->overridable) {
 293                 service_looking_at = service;
 294                 service_enabled = -1;
 295                 git_config(git_daemon_config);
 296                 if (0 <= service_enabled)
 297                         enabled = service_enabled;
 298         }
 299         if (!enabled) {
 300                 logerror("'%s': service not enabled for '%s'",
 301                          service->name, path);
 302                 errno = EACCES;
 303                 return -1;
 304         }
 305
 306         /*
 307          * We'll ignore SIGTERM from now on, we have a
 308          * good client.
 309          */
 310         signal(SIGTERM, SIG_IGN);
 311
 312         return service->fn();
 313 }
 314
 315 static int upload_pack(void)
 316 {
 317         /* Timeout as string */
 318         char timeout_buf[64];
 319
 320         snprintf(timeout_buf, sizeof timeout_buf, "--timeout=%u", timeout);
 321
 322         /* git-upload-pack only ever reads stuff, so this is safe */
 323         execl_git_cmd("upload-pack", "--strict", timeout_buf, ".", NULL);
 324         return -1;
 325 }
 326
 327 static struct daemon_service daemon_service[] = {
 328         { "upload-pack", "uploadpack", upload_pack, 1, 1 },
 329 };
 330
 331 static void enable_service(const char *name, int ena) {
 332         int i;
 333         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 334                 if (!strcmp(daemon_service[i].name, name)) {
 335                         daemon_service[i].enabled = ena;
 336                         return;
 337                 }
 338         }
 339         die("No such service %s", name);
 340 }
 341
 342 static void make_service_overridable(const char *name, int ena) {
 343         int i;
 344         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 345                 if (!strcmp(daemon_service[i].name, name)) {
 346                         daemon_service[i].overridable = ena;
 347                         return;
 348                 }
 349         }
 350         die("No such service %s", name);
 351 }
 352
 353 static int execute(struct sockaddr *addr)
 354 {
 355         static char line[1000];
 356         int pktlen, len, i;
 357
 358         if (addr) {
 359                 char addrbuf[256] = "";
 360                 int port = -1;
 361
 362                 if (addr->sa_family == AF_INET) {
 363                         struct sockaddr_in *sin_addr = (void *) addr;
 364                         inet_ntop(addr->sa_family, &sin_addr->sin_addr, addrbuf, sizeof(addrbuf));
 365                         port = sin_addr->sin_port;
 366 #ifndef NO_IPV6
 367                 } else if (addr && addr->sa_family == AF_INET6) {
 368                         struct sockaddr_in6 *sin6_addr = (void *) addr;
 369
 370                         char *buf = addrbuf;
 371                         *buf++ = '['; *buf = '\0'; /* stpcpy() is cool */
 372                         inet_ntop(AF_INET6, &sin6_addr->sin6_addr, buf, sizeof(addrbuf) - 1);
 373                         strcat(buf, "]");
 374
 375                         port = sin6_addr->sin6_port;
 376 #endif
 377                 }
 378                 loginfo("Connection from %s:%d", addrbuf, port);
 379         }
 380
 381         alarm(init_timeout ? init_timeout : timeout);
 382         pktlen = packet_read_line(0, line, sizeof(line));
 383         alarm(0);
 384
 385         len = strlen(line);
 386         if (pktlen != len)
 387                 loginfo("Extended attributes (%d bytes) exist <%.*s>",
 388                         (int) pktlen - len,
 389                         (int) pktlen - len, line + len + 1);
 390         if (len && line[len-1] == '\n')
 391                 line[--len] = 0;
 392
 393         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 394                 struct daemon_service *s = &(daemon_service[i]);
 395                 int namelen = strlen(s->name);
 396                 if (!strncmp("git-", line, 4) &&
 397                     !strncmp(s->name, line + 4, namelen) &&
 398                     line[namelen + 4] == ' ')
 399                         return run_service(line + namelen + 5, s);
 400         }
 401
 402         logerror("Protocol error: '%s'", line);
 403         return -1;
 404 }
 405
 406
 407 /*
 408  * We count spawned/reaped separately, just to avoid any
 409  * races when updating them from signals. The SIGCHLD handler
 410  * will only update children_reaped, and the fork logic will
 411  * only update children_spawned.
 412  *
 413  * MAX_CHILDREN should be a power-of-two to make the modulus
 414  * operation cheap. It should also be at least twice
 415  * the maximum number of connections we will ever allow.
 416  */
 417 #define MAX_CHILDREN 128
 418
 419 static int max_connections = 25;
 420
 421 /* These are updated by the signal handler */
 422 static volatile unsigned int children_reaped;
 423 static pid_t dead_child[MAX_CHILDREN];
 424
 425 /* These are updated by the main loop */
 426 static unsigned int children_spawned;
 427 static unsigned int children_deleted;
 428
 429 static struct child {
 430         pid_t pid;
 431         int addrlen;
 432         struct sockaddr_storage address;
 433 } live_child[MAX_CHILDREN];
 434
 435 static void add_child(int idx, pid_t pid, struct sockaddr *addr, int addrlen)
 436 {
 437         live_child[idx].pid = pid;
 438         live_child[idx].addrlen = addrlen;
 439         memcpy(&live_child[idx].address, addr, addrlen);
 440 }
 441
 442 /*
 443  * Walk from "deleted" to "spawned", and remove child "pid".
 444  *
 445  * We move everything up by one, since the new "deleted" will
 446  * be one higher.
 447  */
 448 static void remove_child(pid_t pid, unsigned deleted, unsigned spawned)
 449 {
 450         struct child n;
 451
 452         deleted %= MAX_CHILDREN;
 453         spawned %= MAX_CHILDREN;
 454         if (live_child[deleted].pid == pid) {
 455                 live_child[deleted].pid = -1;
 456                 return;
 457         }
 458         n = live_child[deleted];
 459         for (;;) {
 460                 struct child m;
 461                 deleted = (deleted + 1) % MAX_CHILDREN;
 462                 if (deleted == spawned)
 463                         die("could not find dead child %d\n", pid);
 464                 m = live_child[deleted];
 465                 live_child[deleted] = n;
 466                 if (m.pid == pid)
 467                         return;
 468                 n = m;
 469         }
 470 }
 471
 472 /*
 473  * This gets called if the number of connections grows
 474  * past "max_connections".
 475  *
 476  * We _should_ start off by searching for connections
 477  * from the same IP, and if there is some address wth
 478  * multiple connections, we should kill that first.
 479  *
 480  * As it is, we just "randomly" kill 25% of the connections,
 481  * and our pseudo-random generator sucks too. I have no
 482  * shame.
 483  *
 484  * Really, this is just a place-holder for a _real_ algorithm.
 485  */
 486 static void kill_some_children(int signo, unsigned start, unsigned stop)
 487 {
 488         start %= MAX_CHILDREN;
 489         stop %= MAX_CHILDREN;
 490         while (start != stop) {
 491                 if (!(start & 3))
 492                         kill(live_child[start].pid, signo);
 493                 start = (start + 1) % MAX_CHILDREN;
 494         }
 495 }
 496
 497 static void check_max_connections(void)
 498 {
 499         for (;;) {
 500                 int active;
 501                 unsigned spawned, reaped, deleted;
 502
 503                 spawned = children_spawned;
 504                 reaped = children_reaped;
 505                 deleted = children_deleted;
 506
 507                 while (deleted < reaped) {
 508                         pid_t pid = dead_child[deleted % MAX_CHILDREN];
 509                         remove_child(pid, deleted, spawned);
 510                         deleted++;
 511                 }
 512                 children_deleted = deleted;
 513
 514                 active = spawned - deleted;
 515                 if (active <= max_connections)
 516                         break;
 517
 518                 /* Kill some unstarted connections with SIGTERM */
 519                 kill_some_children(SIGTERM, deleted, spawned);
 520                 if (active <= max_connections << 1)
 521                         break;
 522
 523                 /* If the SIGTERM thing isn't helping use SIGKILL */
 524                 kill_some_children(SIGKILL, deleted, spawned);
 525                 sleep(1);
 526         }
 527 }
 528
 529 static void handle(int incoming, struct sockaddr *addr, int addrlen)
 530 {
 531         pid_t pid = fork();
 532
 533         if (pid) {
 534                 unsigned idx;
 535
 536                 close(incoming);
 537                 if (pid < 0)
 538                         return;
 539
 540                 idx = children_spawned % MAX_CHILDREN;
 541                 children_spawned++;
 542                 add_child(idx, pid, addr, addrlen);
 543
 544                 check_max_connections();
 545                 return;
 546         }
 547
 548         dup2(incoming, 0);
 549         dup2(incoming, 1);
 550         close(incoming);
 551
 552         exit(execute(addr));
 553 }
 554
 555 static void child_handler(int signo)
 556 {
 557         for (;;) {
 558                 int status;
 559                 pid_t pid = waitpid(-1, &status, WNOHANG);
 560
 561                 if (pid > 0) {
 562                         unsigned reaped = children_reaped;
 563                         dead_child[reaped % MAX_CHILDREN] = pid;
 564                         children_reaped = reaped + 1;
 565                         /* XXX: Custom logging, since we don't wanna getpid() */
 566                         if (verbose) {
 567                                 const char *dead = "";
 568                                 if (!WIFEXITED(status) || WEXITSTATUS(status) > 0)
 569                                         dead = " (with error)";
 570                                 if (log_syslog)
 571                                         syslog(LOG_INFO, "[%d] Disconnected%s", pid, dead);
 572                                 else
 573                                         fprintf(stderr, "[%d] Disconnected%s\n", pid, dead);
 574                         }
 575                         continue;
 576                 }
 577                 break;
 578         }
 579 }
 580
 581 static int set_reuse_addr(int sockfd)
 582 {
 583         int on = 1;
 584
 585         if (!reuseaddr)
 586                 return 0;
 587         return setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
 588                           &on, sizeof(on));
 589 }
 590
 591 #ifndef NO_IPV6
 592
 593 static int socksetup(int port, int **socklist_p)
 594 {
 595         int socknum = 0, *socklist = NULL;
 596         int maxfd = -1;
 597         char pbuf[NI_MAXSERV];
 598
 599         struct addrinfo hints, *ai0, *ai;
 600         int gai;
 601
 602         sprintf(pbuf, "%d", port);
 603         memset(&hints, 0, sizeof(hints));
 604         hints.ai_family = AF_UNSPEC;
 605         hints.ai_socktype = SOCK_STREAM;
 606         hints.ai_protocol = IPPROTO_TCP;
 607         hints.ai_flags = AI_PASSIVE;
 608
 609         gai = getaddrinfo(NULL, pbuf, &hints, &ai0);
 610         if (gai)
 611                 die("getaddrinfo() failed: %s\n", gai_strerror(gai));
 612
 613         for (ai = ai0; ai; ai = ai->ai_next) {
 614                 int sockfd;
 615
 616                 sockfd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
 617                 if (sockfd < 0)
 618                         continue;
 619                 if (sockfd >= FD_SETSIZE) {
 620                         error("too large socket descriptor.");
 621                         close(sockfd);
 622                         continue;
 623                 }
 624
 625 #ifdef IPV6_V6ONLY
 626                 if (ai->ai_family == AF_INET6) {
 627                         int on = 1;
 628                         setsockopt(sockfd, IPPROTO_IPV6, IPV6_V6ONLY,
 629                                    &on, sizeof(on));
 630                         /* Note: error is not fatal */
 631                 }
 632 #endif
 633
 634                 if (set_reuse_addr(sockfd)) {
 635                         close(sockfd);
 636                         continue;
 637                 }
 638
 639                 if (bind(sockfd, ai->ai_addr, ai->ai_addrlen) < 0) {
 640                         close(sockfd);
 641                         continue;       /* not fatal */
 642                 }
 643                 if (listen(sockfd, 5) < 0) {
 644                         close(sockfd);
 645                         continue;       /* not fatal */
 646                 }
 647
 648                 socklist = xrealloc(socklist, sizeof(int) * (socknum + 1));
 649                 socklist[socknum++] = sockfd;
 650
 651                 if (maxfd < sockfd)
 652                         maxfd = sockfd;
 653         }
 654
 655         freeaddrinfo(ai0);
 656
 657         *socklist_p = socklist;
 658         return socknum;
 659 }
 660
 661 #else /* NO_IPV6 */
 662
 663 static int socksetup(int port, int **socklist_p)
 664 {
 665         struct sockaddr_in sin;
 666         int sockfd;
 667
 668         sockfd = socket(AF_INET, SOCK_STREAM, 0);
 669         if (sockfd < 0)
 670                 return 0;
 671
 672         memset(&sin, 0, sizeof sin);
 673         sin.sin_family = AF_INET;
 674         sin.sin_addr.s_addr = htonl(INADDR_ANY);
 675         sin.sin_port = htons(port);
 676
 677         if (set_reuse_addr(sockfd)) {
 678                 close(sockfd);
 679                 return 0;
 680         }
 681
 682         if ( bind(sockfd, (struct sockaddr *)&sin, sizeof sin) < 0 ) {
 683                 close(sockfd);
 684                 return 0;
 685         }
 686
 687         if (listen(sockfd, 5) < 0) {
 688                 close(sockfd);
 689                 return 0;
 690         }
 691
 692         *socklist_p = xmalloc(sizeof(int));
 693         **socklist_p = sockfd;
 694         return 1;
 695 }
 696
 697 #endif
 698
 699 static int service_loop(int socknum, int *socklist)
 700 {
 701         struct pollfd *pfd;
 702         int i;
 703
 704         pfd = xcalloc(socknum, sizeof(struct pollfd));
 705
 706         for (i = 0; i < socknum; i++) {
 707                 pfd[i].fd = socklist[i];
 708                 pfd[i].events = POLLIN;
 709         }
 710
 711         signal(SIGCHLD, child_handler);
 712
 713         for (;;) {
 714                 int i;
 715
 716                 if (poll(pfd, socknum, -1) < 0) {
 717                         if (errno != EINTR) {
 718                                 error("poll failed, resuming: %s",
 719                                       strerror(errno));
 720                                 sleep(1);
 721                         }
 722                         continue;
 723                 }
 724
 725                 for (i = 0; i < socknum; i++) {
 726                         if (pfd[i].revents & POLLIN) {
 727                                 struct sockaddr_storage ss;
 728                                 unsigned int sslen = sizeof(ss);
 729                                 int incoming = accept(pfd[i].fd, (struct sockaddr *)&ss, &sslen);
 730                                 if (incoming < 0) {
 731                                         switch (errno) {
 732                                         case EAGAIN:
 733                                         case EINTR:
 734                                         case ECONNABORTED:
 735                                                 continue;
 736                                         default:
 737                                                 die("accept returned %s", strerror(errno));
 738                                         }
 739                                 }
 740                                 handle(incoming, (struct sockaddr *)&ss, sslen);
 741                         }
 742                 }
 743         }
 744 }
 745
 746 /* if any standard file descriptor is missing open it to /dev/null */
 747 static void sanitize_stdfds(void)
 748 {
 749         int fd = open("/dev/null", O_RDWR, 0);
 750         while (fd != -1 && fd < 2)
 751                 fd = dup(fd);
 752         if (fd == -1)
 753                 die("open /dev/null or dup failed: %s", strerror(errno));
 754         if (fd > 2)
 755                 close(fd);
 756 }
 757
 758 static void daemonize(void)
 759 {
 760         switch (fork()) {
 761                 case 0:
 762                         break;
 763                 case -1:
 764                         die("fork failed: %s", strerror(errno));
 765                 default:
 766                         exit(0);
 767         }
 768         if (setsid() == -1)
 769                 die("setsid failed: %s", strerror(errno));
 770         close(0);
 771         close(1);
 772         close(2);
 773         sanitize_stdfds();
 774 }
 775
 776 static void store_pid(const char *path)
 777 {
 778         FILE *f = fopen(path, "w");
 779         if (!f)
 780                 die("cannot open pid file %s: %s", path, strerror(errno));
 781         fprintf(f, "%d\n", getpid());
 782         fclose(f);
 783 }
 784
 785 static int serve(int port, struct passwd *pass, gid_t gid)
 786 {
 787         int socknum, *socklist;
 788
 789         socknum = socksetup(port, &socklist);
 790         if (socknum == 0)
 791                 die("unable to allocate any listen sockets on port %u", port);
 792
 793         if (pass && gid &&
 794             (initgroups(pass->pw_name, gid) || setgid (gid) ||
 795              setuid(pass->pw_uid)))
 796                 die("cannot drop privileges");
 797
 798         return service_loop(socknum, socklist);
 799 }
 800
 801 int main(int argc, char **argv)
 802 {
 803         int port = DEFAULT_GIT_PORT;
 804         int inetd_mode = 0;
 805         const char *pid_file = NULL, *user_name = NULL, *group_name = NULL;
 806         int detach = 0;
 807         struct passwd *pass = NULL;
 808         struct group *group;
 809         gid_t gid = 0;
 810         int i;
 811
 812         /* Without this we cannot rely on waitpid() to tell
 813          * what happened to our children.
 814          */
 815         signal(SIGCHLD, SIG_DFL);
 816
 817         for (i = 1; i < argc; i++) {
 818                 char *arg = argv[i];
 819
 820                 if (!strncmp(arg, "--port=", 7)) {
 821                         char *end;
 822                         unsigned long n;
 823                         n = strtoul(arg+7, &end, 0);
 824                         if (arg[7] && !*end) {
 825                                 port = n;
 826                                 continue;
 827                         }
 828                 }
 829                 if (!strcmp(arg, "--inetd")) {
 830                         inetd_mode = 1;
 831                         log_syslog = 1;
 832                         continue;
 833                 }
 834                 if (!strcmp(arg, "--verbose")) {
 835                         verbose = 1;
 836                         continue;
 837                 }
 838                 if (!strcmp(arg, "--syslog")) {
 839                         log_syslog = 1;
 840                         continue;
 841                 }
 842                 if (!strcmp(arg, "--export-all")) {
 843                         export_all_trees = 1;
 844                         continue;
 845                 }
 846                 if (!strncmp(arg, "--timeout=", 10)) {
 847                         timeout = atoi(arg+10);
 848                         continue;
 849                 }
 850                 if (!strncmp(arg, "--init-timeout=", 15)) {
 851                         init_timeout = atoi(arg+15);
 852                         continue;
 853                 }
 854                 if (!strcmp(arg, "--strict-paths")) {
 855                         strict_paths = 1;
 856                         continue;
 857                 }
 858                 if (!strncmp(arg, "--base-path=", 12)) {
 859                         base_path = arg+12;
 860                         continue;
 861                 }
 862                 if (!strcmp(arg, "--reuseaddr")) {
 863                         reuseaddr = 1;
 864                         continue;
 865                 }
 866                 if (!strcmp(arg, "--user-path")) {
 867                         user_path = "";
 868                         continue;
 869                 }
 870                 if (!strncmp(arg, "--user-path=", 12)) {
 871                         user_path = arg + 12;
 872                         continue;
 873                 }
 874                 if (!strncmp(arg, "--pid-file=", 11)) {
 875                         pid_file = arg + 11;
 876                         continue;
 877                 }
 878                 if (!strcmp(arg, "--detach")) {
 879                         detach = 1;
 880                         log_syslog = 1;
 881                         continue;
 882                 }
 883                 if (!strncmp(arg, "--user=", 7)) {
 884                         user_name = arg + 7;
 885                         continue;
 886                 }
 887                 if (!strncmp(arg, "--group=", 8)) {
 888                         group_name = arg + 8;
 889                         continue;
 890                 }
 891                 if (!strncmp(arg, "--enable=", 9)) {
 892                         enable_service(arg + 9, 1);
 893                         continue;
 894                 }
 895                 if (!strncmp(arg, "--disable=", 10)) {
 896                         enable_service(arg + 10, 0);
 897                         continue;
 898                 }
 899                 if (!strncmp(arg, "--enable-override=", 18)) {
 900                         make_service_overridable(arg + 18, 1);
 901                         continue;
 902                 }
 903                 if (!strncmp(arg, "--disable-override=", 19)) {
 904                         make_service_overridable(arg + 19, 0);
 905                         continue;
 906                 }
 907                 if (!strcmp(arg, "--")) {
 908                         ok_paths = &argv[i+1];
 909                         break;
 910                 } else if (arg[0] != '-') {
 911                         ok_paths = &argv[i];
 912                         break;
 913                 }
 914
 915                 usage(daemon_usage);
 916         }
 917
 918         if (inetd_mode && (group_name || user_name))
 919                 die("--user and --group are incompatible with --inetd");
 920
 921         if (group_name && !user_name)
 922                 die("--group supplied without --user");
 923
 924         if (user_name) {
 925                 pass = getpwnam(user_name);
 926                 if (!pass)
 927                         die("user not found - %s", user_name);
 928
 929                 if (!group_name)
 930                         gid = pass->pw_gid;
 931                 else {
 932                         group = getgrnam(group_name);
 933                         if (!group)
 934                                 die("group not found - %s", group_name);
 935
 936                         gid = group->gr_gid;
 937                 }
 938         }
 939
 940         if (log_syslog) {
 941                 openlog("git-daemon", 0, LOG_DAEMON);
 942                 set_die_routine(daemon_die);
 943         }
 944
 945         if (strict_paths && (!ok_paths || !*ok_paths))
 946                 die("option --strict-paths requires a whitelist");
 947
 948         if (inetd_mode) {
 949                 struct sockaddr_storage ss;
 950                 struct sockaddr *peer = (struct sockaddr *)&ss;
 951                 socklen_t slen = sizeof(ss);
 952
 953                 freopen("/dev/null", "w", stderr);
 954
 955                 if (getpeername(0, peer, &slen))
 956                         peer = NULL;
 957
 958                 return execute(peer);
 959         }
 960
 961         if (detach)
 962                 daemonize();
 963         else
 964                 sanitize_stdfds();
 965
 966         if (pid_file)
 967                 store_pid(pid_file);
 968
 969         return serve(port, pass, gid);
 970 }