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 "           [--[enable|disable|allow-override|forbid-override]=service]\n"
  26 "           [--user=user [[--group=group]] [directory...]";
  27
  28 /* List of acceptable pathname prefixes */
  29 static char **ok_paths;
  30 static int strict_paths;
  31
  32 /* If this is set, git-daemon-export-ok is not required */
  33 static int export_all_trees;
  34
  35 /* Take all paths relative to this one if non-NULL */
  36 static char *base_path;
  37
  38 /* If defined, ~user notation is allowed and the string is inserted
  39  * after ~user/.  E.g. a request to git://host/~alice/frotz would
  40  * go to /home/alice/pub_git/frotz with --user-path=pub_git.
  41  */
  42 static const char *user_path;
  43
  44 /* Timeout, and initial timeout */
  45 static unsigned int timeout;
  46 static unsigned int init_timeout;
  47
  48 static void logreport(int priority, const char *err, va_list params)
  49 {
  50         /* We should do a single write so that it is atomic and output
  51          * of several processes do not get intermingled. */
  52         char buf[1024];
  53         int buflen;
  54         int maxlen, msglen;
  55
  56         /* sizeof(buf) should be big enough for "[pid] \n" */
  57         buflen = snprintf(buf, sizeof(buf), "[%ld] ", (long) getpid());
  58
  59         maxlen = sizeof(buf) - buflen - 1; /* -1 for our own LF */
  60         msglen = vsnprintf(buf + buflen, maxlen, err, params);
  61
  62         if (log_syslog) {
  63                 syslog(priority, "%s", buf);
  64                 return;
  65         }
  66
  67         /* maxlen counted our own LF but also counts space given to
  68          * vsnprintf for the terminating NUL.  We want to make sure that
  69          * we have space for our own LF and NUL after the "meat" of the
  70          * message, so truncate it at maxlen - 1.
  71          */
  72         if (msglen > maxlen - 1)
  73                 msglen = maxlen - 1;
  74         else if (msglen < 0)
  75                 msglen = 0; /* Protect against weird return values. */
  76         buflen += msglen;
  77
  78         buf[buflen++] = '\n';
  79         buf[buflen] = '\0';
  80
  81         write(2, buf, buflen);
  82 }
  83
  84 static void logerror(const char *err, ...)
  85 {
  86         va_list params;
  87         va_start(params, err);
  88         logreport(LOG_ERR, err, params);
  89         va_end(params);
  90 }
  91
  92 static void loginfo(const char *err, ...)
  93 {
  94         va_list params;
  95         if (!verbose)
  96                 return;
  97         va_start(params, err);
  98         logreport(LOG_INFO, err, params);
  99         va_end(params);
 100 }
 101
 102 static void NORETURN daemon_die(const char *err, va_list params)
 103 {
 104         logreport(LOG_ERR, err, params);
 105         exit(1);
 106 }
 107
 108 static int avoid_alias(char *p)
 109 {
 110         int sl, ndot;
 111
 112         /*
 113          * This resurrects the belts and suspenders paranoia check by HPA
 114          * done in <435560F7.4080006@zytor.com> thread, now enter_repo()
 115          * does not do getcwd() based path canonicalizations.
 116          *
 117          * sl becomes true immediately after seeing '/' and continues to
 118          * be true as long as dots continue after that without intervening
 119          * non-dot character.
 120          */
 121         if (!p || (*p != '/' && *p != '~'))
 122                 return -1;
 123         sl = 1; ndot = 0;
 124         p++;
 125
 126         while (1) {
 127                 char ch = *p++;
 128                 if (sl) {
 129                         if (ch == '.')
 130                                 ndot++;
 131                         else if (ch == '/') {
 132                                 if (ndot < 3)
 133                                         /* reject //, /./ and /../ */
 134                                         return -1;
 135                                 ndot = 0;
 136                         }
 137                         else if (ch == 0) {
 138                                 if (0 < ndot && ndot < 3)
 139                                         /* reject /.$ and /..$ */
 140                                         return -1;
 141                                 return 0;
 142                         }
 143                         else
 144                                 sl = ndot = 0;
 145                 }
 146                 else if (ch == 0)
 147                         return 0;
 148                 else if (ch == '/') {
 149                         sl = 1;
 150                         ndot = 0;
 151                 }
 152         }
 153 }
 154
 155 static char *path_ok(char *dir)
 156 {
 157         static char rpath[PATH_MAX];
 158         char *path;
 159
 160         if (avoid_alias(dir)) {
 161                 logerror("'%s': aliased", dir);
 162                 return NULL;
 163         }
 164
 165         if (*dir == '~') {
 166                 if (!user_path) {
 167                         logerror("'%s': User-path not allowed", dir);
 168                         return NULL;
 169                 }
 170                 if (*user_path) {
 171                         /* Got either "~alice" or "~alice/foo";
 172                          * rewrite them to "~alice/%s" or
 173                          * "~alice/%s/foo".
 174                          */
 175                         int namlen, restlen = strlen(dir);
 176                         char *slash = strchr(dir, '/');
 177                         if (!slash)
 178                                 slash = dir + restlen;
 179                         namlen = slash - dir;
 180                         restlen -= namlen;
 181                         loginfo("userpath <%s>, request <%s>, namlen %d, restlen %d, slash <%s>", user_path, dir, namlen, restlen, slash);
 182                         snprintf(rpath, PATH_MAX, "%.*s/%s%.*s",
 183                                  namlen, dir, user_path, restlen, slash);
 184                         dir = rpath;
 185                 }
 186         }
 187         else if (base_path) {
 188                 if (*dir != '/') {
 189                         /* Allow only absolute */
 190                         logerror("'%s': Non-absolute path denied (base-path active)", dir);
 191                         return NULL;
 192                 }
 193                 else {
 194                         snprintf(rpath, PATH_MAX, "%s%s", base_path, dir);
 195                         dir = rpath;
 196                 }
 197         }
 198
 199         path = enter_repo(dir, strict_paths);
 200
 201         if (!path) {
 202                 logerror("'%s': unable to chdir or not a git archive", dir);
 203                 return NULL;
 204         }
 205
 206         if ( ok_paths && *ok_paths ) {
 207                 char **pp;
 208                 int pathlen = strlen(path);
 209
 210                 /* The validation is done on the paths after enter_repo
 211                  * appends optional {.git,.git/.git} and friends, but
 212                  * it does not use getcwd().  So if your /pub is
 213                  * a symlink to /mnt/pub, you can whitelist /pub and
 214                  * do not have to say /mnt/pub.
 215                  * Do not say /pub/.
 216                  */
 217                 for ( pp = ok_paths ; *pp ; pp++ ) {
 218                         int len = strlen(*pp);
 219                         if (len <= pathlen &&
 220                             !memcmp(*pp, path, len) &&
 221                             (path[len] == '\0' ||
 222                              (!strict_paths && path[len] == '/')))
 223                                 return path;
 224                 }
 225         }
 226         else {
 227                 /* be backwards compatible */
 228                 if (!strict_paths)
 229                         return path;
 230         }
 231
 232         logerror("'%s': not in whitelist", path);
 233         return NULL;            /* Fallthrough. Deny by default */
 234 }
 235
 236 typedef int (*daemon_service_fn)(void);
 237 struct daemon_service {
 238         const char *name;
 239         const char *config_name;
 240         daemon_service_fn fn;
 241         int enabled;
 242         int overridable;
 243 };
 244
 245 static struct daemon_service *service_looking_at;
 246 static int service_enabled;
 247
 248 static int git_daemon_config(const char *var, const char *value)
 249 {
 250         if (!strncmp(var, "daemon.", 7) &&
 251             !strcmp(var + 7, service_looking_at->config_name)) {
 252                 service_enabled = git_config_bool(var, value);
 253                 return 0;
 254         }
 255
 256         /* we are not interested in parsing any other configuration here */
 257         return 0;
 258 }
 259
 260 static int run_service(char *dir, struct daemon_service *service)
 261 {
 262         const char *path;
 263         int enabled = service->enabled;
 264
 265         loginfo("Request %s for '%s'", service->name, dir);
 266
 267         if (!enabled && !service->overridable) {
 268                 logerror("'%s': service not enabled.", service->name);
 269                 errno = EACCES;
 270                 return -1;
 271         }
 272
 273         if (!(path = path_ok(dir)))
 274                 return -1;
 275
 276         /*
 277          * Security on the cheap.
 278          *
 279          * We want a readable HEAD, usable "objects" directory, and
 280          * a "git-daemon-export-ok" flag that says that the other side
 281          * is ok with us doing this.
 282          *
 283          * path_ok() uses enter_repo() and does whitelist checking.
 284          * We only need to make sure the repository is exported.
 285          */
 286
 287         if (!export_all_trees && access("git-daemon-export-ok", F_OK)) {
 288                 logerror("'%s': repository not exported.", path);
 289                 errno = EACCES;
 290                 return -1;
 291         }
 292
 293         if (service->overridable) {
 294                 service_looking_at = service;
 295                 service_enabled = -1;
 296                 git_config(git_daemon_config);
 297                 if (0 <= service_enabled)
 298                         enabled = service_enabled;
 299         }
 300         if (!enabled) {
 301                 logerror("'%s': service not enabled for '%s'",
 302                          service->name, path);
 303                 errno = EACCES;
 304                 return -1;
 305         }
 306
 307         /*
 308          * We'll ignore SIGTERM from now on, we have a
 309          * good client.
 310          */
 311         signal(SIGTERM, SIG_IGN);
 312
 313         return service->fn();
 314 }
 315
 316 static int upload_pack(void)
 317 {
 318         /* Timeout as string */
 319         char timeout_buf[64];
 320
 321         snprintf(timeout_buf, sizeof timeout_buf, "--timeout=%u", timeout);
 322
 323         /* git-upload-pack only ever reads stuff, so this is safe */
 324         execl_git_cmd("upload-pack", "--strict", timeout_buf, ".", NULL);
 325         return -1;
 326 }
 327
 328 static int upload_archive(void)
 329 {
 330         execl_git_cmd("upload-archive", ".", NULL);
 331         return -1;
 332 }
 333
 334 static struct daemon_service daemon_service[] = {
 335         { "upload-archive", "uploadarch", upload_archive, 0, 1 },
 336         { "upload-pack", "uploadpack", upload_pack, 1, 1 },
 337 };
 338
 339 static void enable_service(const char *name, int ena) {
 340         int i;
 341         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 342                 if (!strcmp(daemon_service[i].name, name)) {
 343                         daemon_service[i].enabled = ena;
 344                         return;
 345                 }
 346         }
 347         die("No such service %s", name);
 348 }
 349
 350 static void make_service_overridable(const char *name, int ena) {
 351         int i;
 352         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 353                 if (!strcmp(daemon_service[i].name, name)) {
 354                         daemon_service[i].overridable = ena;
 355                         return;
 356                 }
 357         }
 358         die("No such service %s", name);
 359 }
 360
 361 static int execute(struct sockaddr *addr)
 362 {
 363         static char line[1000];
 364         int pktlen, len, i;
 365
 366         if (addr) {
 367                 char addrbuf[256] = "";
 368                 int port = -1;
 369
 370                 if (addr->sa_family == AF_INET) {
 371                         struct sockaddr_in *sin_addr = (void *) addr;
 372                         inet_ntop(addr->sa_family, &sin_addr->sin_addr, addrbuf, sizeof(addrbuf));
 373                         port = sin_addr->sin_port;
 374 #ifndef NO_IPV6
 375                 } else if (addr && addr->sa_family == AF_INET6) {
 376                         struct sockaddr_in6 *sin6_addr = (void *) addr;
 377
 378                         char *buf = addrbuf;
 379                         *buf++ = '['; *buf = '\0'; /* stpcpy() is cool */
 380                         inet_ntop(AF_INET6, &sin6_addr->sin6_addr, buf, sizeof(addrbuf) - 1);
 381                         strcat(buf, "]");
 382
 383                         port = sin6_addr->sin6_port;
 384 #endif
 385                 }
 386                 loginfo("Connection from %s:%d", addrbuf, port);
 387         }
 388
 389         alarm(init_timeout ? init_timeout : timeout);
 390         pktlen = packet_read_line(0, line, sizeof(line));
 391         alarm(0);
 392
 393         len = strlen(line);
 394         if (pktlen != len)
 395                 loginfo("Extended attributes (%d bytes) exist <%.*s>",
 396                         (int) pktlen - len,
 397                         (int) pktlen - len, line + len + 1);
 398         if (len && line[len-1] == '\n')
 399                 line[--len] = 0;
 400
 401         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 402                 struct daemon_service *s = &(daemon_service[i]);
 403                 int namelen = strlen(s->name);
 404                 if (!strncmp("git-", line, 4) &&
 405                     !strncmp(s->name, line + 4, namelen) &&
 406                     line[namelen + 4] == ' ')
 407                         return run_service(line + namelen + 5, s);
 408         }
 409
 410         logerror("Protocol error: '%s'", line);
 411         return -1;
 412 }
 413
 414
 415 /*
 416  * We count spawned/reaped separately, just to avoid any
 417  * races when updating them from signals. The SIGCHLD handler
 418  * will only update children_reaped, and the fork logic will
 419  * only update children_spawned.
 420  *
 421  * MAX_CHILDREN should be a power-of-two to make the modulus
 422  * operation cheap. It should also be at least twice
 423  * the maximum number of connections we will ever allow.
 424  */
 425 #define MAX_CHILDREN 128
 426
 427 static int max_connections = 25;
 428
 429 /* These are updated by the signal handler */
 430 static volatile unsigned int children_reaped;
 431 static pid_t dead_child[MAX_CHILDREN];
 432
 433 /* These are updated by the main loop */
 434 static unsigned int children_spawned;
 435 static unsigned int children_deleted;
 436
 437 static struct child {
 438         pid_t pid;
 439         int addrlen;
 440         struct sockaddr_storage address;
 441 } live_child[MAX_CHILDREN];
 442
 443 static void add_child(int idx, pid_t pid, struct sockaddr *addr, int addrlen)
 444 {
 445         live_child[idx].pid = pid;
 446         live_child[idx].addrlen = addrlen;
 447         memcpy(&live_child[idx].address, addr, addrlen);
 448 }
 449
 450 /*
 451  * Walk from "deleted" to "spawned", and remove child "pid".
 452  *
 453  * We move everything up by one, since the new "deleted" will
 454  * be one higher.
 455  */
 456 static void remove_child(pid_t pid, unsigned deleted, unsigned spawned)
 457 {
 458         struct child n;
 459
 460         deleted %= MAX_CHILDREN;
 461         spawned %= MAX_CHILDREN;
 462         if (live_child[deleted].pid == pid) {
 463                 live_child[deleted].pid = -1;
 464                 return;
 465         }
 466         n = live_child[deleted];
 467         for (;;) {
 468                 struct child m;
 469                 deleted = (deleted + 1) % MAX_CHILDREN;
 470                 if (deleted == spawned)
 471                         die("could not find dead child %d\n", pid);
 472                 m = live_child[deleted];
 473                 live_child[deleted] = n;
 474                 if (m.pid == pid)
 475                         return;
 476                 n = m;
 477         }
 478 }
 479
 480 /*
 481  * This gets called if the number of connections grows
 482  * past "max_connections".
 483  *
 484  * We _should_ start off by searching for connections
 485  * from the same IP, and if there is some address wth
 486  * multiple connections, we should kill that first.
 487  *
 488  * As it is, we just "randomly" kill 25% of the connections,
 489  * and our pseudo-random generator sucks too. I have no
 490  * shame.
 491  *
 492  * Really, this is just a place-holder for a _real_ algorithm.
 493  */
 494 static void kill_some_children(int signo, unsigned start, unsigned stop)
 495 {
 496         start %= MAX_CHILDREN;
 497         stop %= MAX_CHILDREN;
 498         while (start != stop) {
 499                 if (!(start & 3))
 500                         kill(live_child[start].pid, signo);
 501                 start = (start + 1) % MAX_CHILDREN;
 502         }
 503 }
 504
 505 static void check_max_connections(void)
 506 {
 507         for (;;) {
 508                 int active;
 509                 unsigned spawned, reaped, deleted;
 510
 511                 spawned = children_spawned;
 512                 reaped = children_reaped;
 513                 deleted = children_deleted;
 514
 515                 while (deleted < reaped) {
 516                         pid_t pid = dead_child[deleted % MAX_CHILDREN];
 517                         remove_child(pid, deleted, spawned);
 518                         deleted++;
 519                 }
 520                 children_deleted = deleted;
 521
 522                 active = spawned - deleted;
 523                 if (active <= max_connections)
 524                         break;
 525
 526                 /* Kill some unstarted connections with SIGTERM */
 527                 kill_some_children(SIGTERM, deleted, spawned);
 528                 if (active <= max_connections << 1)
 529                         break;
 530
 531                 /* If the SIGTERM thing isn't helping use SIGKILL */
 532                 kill_some_children(SIGKILL, deleted, spawned);
 533                 sleep(1);
 534         }
 535 }
 536
 537 static void handle(int incoming, struct sockaddr *addr, int addrlen)
 538 {
 539         pid_t pid = fork();
 540
 541         if (pid) {
 542                 unsigned idx;
 543
 544                 close(incoming);
 545                 if (pid < 0)
 546                         return;
 547
 548                 idx = children_spawned % MAX_CHILDREN;
 549                 children_spawned++;
 550                 add_child(idx, pid, addr, addrlen);
 551
 552                 check_max_connections();
 553                 return;
 554         }
 555
 556         dup2(incoming, 0);
 557         dup2(incoming, 1);
 558         close(incoming);
 559
 560         exit(execute(addr));
 561 }
 562
 563 static void child_handler(int signo)
 564 {
 565         for (;;) {
 566                 int status;
 567                 pid_t pid = waitpid(-1, &status, WNOHANG);
 568
 569                 if (pid > 0) {
 570                         unsigned reaped = children_reaped;
 571                         dead_child[reaped % MAX_CHILDREN] = pid;
 572                         children_reaped = reaped + 1;
 573                         /* XXX: Custom logging, since we don't wanna getpid() */
 574                         if (verbose) {
 575                                 const char *dead = "";
 576                                 if (!WIFEXITED(status) || WEXITSTATUS(status) > 0)
 577                                         dead = " (with error)";
 578                                 if (log_syslog)
 579                                         syslog(LOG_INFO, "[%d] Disconnected%s", pid, dead);
 580                                 else
 581                                         fprintf(stderr, "[%d] Disconnected%s\n", pid, dead);
 582                         }
 583                         continue;
 584                 }
 585                 break;
 586         }
 587 }
 588
 589 static int set_reuse_addr(int sockfd)
 590 {
 591         int on = 1;
 592
 593         if (!reuseaddr)
 594                 return 0;
 595         return setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
 596                           &on, sizeof(on));
 597 }
 598
 599 #ifndef NO_IPV6
 600
 601 static int socksetup(int port, int **socklist_p)
 602 {
 603         int socknum = 0, *socklist = NULL;
 604         int maxfd = -1;
 605         char pbuf[NI_MAXSERV];
 606
 607         struct addrinfo hints, *ai0, *ai;
 608         int gai;
 609
 610         sprintf(pbuf, "%d", port);
 611         memset(&hints, 0, sizeof(hints));
 612         hints.ai_family = AF_UNSPEC;
 613         hints.ai_socktype = SOCK_STREAM;
 614         hints.ai_protocol = IPPROTO_TCP;
 615         hints.ai_flags = AI_PASSIVE;
 616
 617         gai = getaddrinfo(NULL, pbuf, &hints, &ai0);
 618         if (gai)
 619                 die("getaddrinfo() failed: %s\n", gai_strerror(gai));
 620
 621         for (ai = ai0; ai; ai = ai->ai_next) {
 622                 int sockfd;
 623
 624                 sockfd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
 625                 if (sockfd < 0)
 626                         continue;
 627                 if (sockfd >= FD_SETSIZE) {
 628                         error("too large socket descriptor.");
 629                         close(sockfd);
 630                         continue;
 631                 }
 632
 633 #ifdef IPV6_V6ONLY
 634                 if (ai->ai_family == AF_INET6) {
 635                         int on = 1;
 636                         setsockopt(sockfd, IPPROTO_IPV6, IPV6_V6ONLY,
 637                                    &on, sizeof(on));
 638                         /* Note: error is not fatal */
 639                 }
 640 #endif
 641
 642                 if (set_reuse_addr(sockfd)) {
 643                         close(sockfd);
 644                         continue;
 645                 }
 646
 647                 if (bind(sockfd, ai->ai_addr, ai->ai_addrlen) < 0) {
 648                         close(sockfd);
 649                         continue;       /* not fatal */
 650                 }
 651                 if (listen(sockfd, 5) < 0) {
 652                         close(sockfd);
 653                         continue;       /* not fatal */
 654                 }
 655
 656                 socklist = xrealloc(socklist, sizeof(int) * (socknum + 1));
 657                 socklist[socknum++] = sockfd;
 658
 659                 if (maxfd < sockfd)
 660                         maxfd = sockfd;
 661         }
 662
 663         freeaddrinfo(ai0);
 664
 665         *socklist_p = socklist;
 666         return socknum;
 667 }
 668
 669 #else /* NO_IPV6 */
 670
 671 static int socksetup(int port, int **socklist_p)
 672 {
 673         struct sockaddr_in sin;
 674         int sockfd;
 675
 676         sockfd = socket(AF_INET, SOCK_STREAM, 0);
 677         if (sockfd < 0)
 678                 return 0;
 679
 680         memset(&sin, 0, sizeof sin);
 681         sin.sin_family = AF_INET;
 682         sin.sin_addr.s_addr = htonl(INADDR_ANY);
 683         sin.sin_port = htons(port);
 684
 685         if (set_reuse_addr(sockfd)) {
 686                 close(sockfd);
 687                 return 0;
 688         }
 689
 690         if ( bind(sockfd, (struct sockaddr *)&sin, sizeof sin) < 0 ) {
 691                 close(sockfd);
 692                 return 0;
 693         }
 694
 695         if (listen(sockfd, 5) < 0) {
 696                 close(sockfd);
 697                 return 0;
 698         }
 699
 700         *socklist_p = xmalloc(sizeof(int));
 701         **socklist_p = sockfd;
 702         return 1;
 703 }
 704
 705 #endif
 706
 707 static int service_loop(int socknum, int *socklist)
 708 {
 709         struct pollfd *pfd;
 710         int i;
 711
 712         pfd = xcalloc(socknum, sizeof(struct pollfd));
 713
 714         for (i = 0; i < socknum; i++) {
 715                 pfd[i].fd = socklist[i];
 716                 pfd[i].events = POLLIN;
 717         }
 718
 719         signal(SIGCHLD, child_handler);
 720
 721         for (;;) {
 722                 int i;
 723
 724                 if (poll(pfd, socknum, -1) < 0) {
 725                         if (errno != EINTR) {
 726                                 error("poll failed, resuming: %s",
 727                                       strerror(errno));
 728                                 sleep(1);
 729                         }
 730                         continue;
 731                 }
 732
 733                 for (i = 0; i < socknum; i++) {
 734                         if (pfd[i].revents & POLLIN) {
 735                                 struct sockaddr_storage ss;
 736                                 unsigned int sslen = sizeof(ss);
 737                                 int incoming = accept(pfd[i].fd, (struct sockaddr *)&ss, &sslen);
 738                                 if (incoming < 0) {
 739                                         switch (errno) {
 740                                         case EAGAIN:
 741                                         case EINTR:
 742                                         case ECONNABORTED:
 743                                                 continue;
 744                                         default:
 745                                                 die("accept returned %s", strerror(errno));
 746                                         }
 747                                 }
 748                                 handle(incoming, (struct sockaddr *)&ss, sslen);
 749                         }
 750                 }
 751         }
 752 }
 753
 754 /* if any standard file descriptor is missing open it to /dev/null */
 755 static void sanitize_stdfds(void)
 756 {
 757         int fd = open("/dev/null", O_RDWR, 0);
 758         while (fd != -1 && fd < 2)
 759                 fd = dup(fd);
 760         if (fd == -1)
 761                 die("open /dev/null or dup failed: %s", strerror(errno));
 762         if (fd > 2)
 763                 close(fd);
 764 }
 765
 766 static void daemonize(void)
 767 {
 768         switch (fork()) {
 769                 case 0:
 770                         break;
 771                 case -1:
 772                         die("fork failed: %s", strerror(errno));
 773                 default:
 774                         exit(0);
 775         }
 776         if (setsid() == -1)
 777                 die("setsid failed: %s", strerror(errno));
 778         close(0);
 779         close(1);
 780         close(2);
 781         sanitize_stdfds();
 782 }
 783
 784 static void store_pid(const char *path)
 785 {
 786         FILE *f = fopen(path, "w");
 787         if (!f)
 788                 die("cannot open pid file %s: %s", path, strerror(errno));
 789         fprintf(f, "%d\n", getpid());
 790         fclose(f);
 791 }
 792
 793 static int serve(int port, struct passwd *pass, gid_t gid)
 794 {
 795         int socknum, *socklist;
 796
 797         socknum = socksetup(port, &socklist);
 798         if (socknum == 0)
 799                 die("unable to allocate any listen sockets on port %u", port);
 800
 801         if (pass && gid &&
 802             (initgroups(pass->pw_name, gid) || setgid (gid) ||
 803              setuid(pass->pw_uid)))
 804                 die("cannot drop privileges");
 805
 806         return service_loop(socknum, socklist);
 807 }
 808
 809 int main(int argc, char **argv)
 810 {
 811         int port = DEFAULT_GIT_PORT;
 812         int inetd_mode = 0;
 813         const char *pid_file = NULL, *user_name = NULL, *group_name = NULL;
 814         int detach = 0;
 815         struct passwd *pass = NULL;
 816         struct group *group;
 817         gid_t gid = 0;
 818         int i;
 819
 820         /* Without this we cannot rely on waitpid() to tell
 821          * what happened to our children.
 822          */
 823         signal(SIGCHLD, SIG_DFL);
 824
 825         for (i = 1; i < argc; i++) {
 826                 char *arg = argv[i];
 827
 828                 if (!strncmp(arg, "--port=", 7)) {
 829                         char *end;
 830                         unsigned long n;
 831                         n = strtoul(arg+7, &end, 0);
 832                         if (arg[7] && !*end) {
 833                                 port = n;
 834                                 continue;
 835                         }
 836                 }
 837                 if (!strcmp(arg, "--inetd")) {
 838                         inetd_mode = 1;
 839                         log_syslog = 1;
 840                         continue;
 841                 }
 842                 if (!strcmp(arg, "--verbose")) {
 843                         verbose = 1;
 844                         continue;
 845                 }
 846                 if (!strcmp(arg, "--syslog")) {
 847                         log_syslog = 1;
 848                         continue;
 849                 }
 850                 if (!strcmp(arg, "--export-all")) {
 851                         export_all_trees = 1;
 852                         continue;
 853                 }
 854                 if (!strncmp(arg, "--timeout=", 10)) {
 855                         timeout = atoi(arg+10);
 856                         continue;
 857                 }
 858                 if (!strncmp(arg, "--init-timeout=", 15)) {
 859                         init_timeout = atoi(arg+15);
 860                         continue;
 861                 }
 862                 if (!strcmp(arg, "--strict-paths")) {
 863                         strict_paths = 1;
 864                         continue;
 865                 }
 866                 if (!strncmp(arg, "--base-path=", 12)) {
 867                         base_path = arg+12;
 868                         continue;
 869                 }
 870                 if (!strcmp(arg, "--reuseaddr")) {
 871                         reuseaddr = 1;
 872                         continue;
 873                 }
 874                 if (!strcmp(arg, "--user-path")) {
 875                         user_path = "";
 876                         continue;
 877                 }
 878                 if (!strncmp(arg, "--user-path=", 12)) {
 879                         user_path = arg + 12;
 880                         continue;
 881                 }
 882                 if (!strncmp(arg, "--pid-file=", 11)) {
 883                         pid_file = arg + 11;
 884                         continue;
 885                 }
 886                 if (!strcmp(arg, "--detach")) {
 887                         detach = 1;
 888                         log_syslog = 1;
 889                         continue;
 890                 }
 891                 if (!strncmp(arg, "--user=", 7)) {
 892                         user_name = arg + 7;
 893                         continue;
 894                 }
 895                 if (!strncmp(arg, "--group=", 8)) {
 896                         group_name = arg + 8;
 897                         continue;
 898                 }
 899                 if (!strncmp(arg, "--enable=", 9)) {
 900                         enable_service(arg + 9, 1);
 901                         continue;
 902                 }
 903                 if (!strncmp(arg, "--disable=", 10)) {
 904                         enable_service(arg + 10, 0);
 905                         continue;
 906                 }
 907                 if (!strncmp(arg, "--allow-override=", 17)) {
 908                         make_service_overridable(arg + 17, 1);
 909                         continue;
 910                 }
 911                 if (!strncmp(arg, "--forbid-override=", 18)) {
 912                         make_service_overridable(arg + 18, 0);
 913                         continue;
 914                 }
 915                 if (!strcmp(arg, "--")) {
 916                         ok_paths = &argv[i+1];
 917                         break;
 918                 } else if (arg[0] != '-') {
 919                         ok_paths = &argv[i];
 920                         break;
 921                 }
 922
 923                 usage(daemon_usage);
 924         }
 925
 926         if (inetd_mode && (group_name || user_name))
 927                 die("--user and --group are incompatible with --inetd");
 928
 929         if (group_name && !user_name)
 930                 die("--group supplied without --user");
 931
 932         if (user_name) {
 933                 pass = getpwnam(user_name);
 934                 if (!pass)
 935                         die("user not found - %s", user_name);
 936
 937                 if (!group_name)
 938                         gid = pass->pw_gid;
 939                 else {
 940                         group = getgrnam(group_name);
 941                         if (!group)
 942                                 die("group not found - %s", group_name);
 943
 944                         gid = group->gr_gid;
 945                 }
 946         }
 947
 948         if (log_syslog) {
 949                 openlog("git-daemon", 0, LOG_DAEMON);
 950                 set_die_routine(daemon_die);
 951         }
 952
 953         if (strict_paths && (!ok_paths || !*ok_paths))
 954                 die("option --strict-paths requires a whitelist");
 955
 956         if (inetd_mode) {
 957                 struct sockaddr_storage ss;
 958                 struct sockaddr *peer = (struct sockaddr *)&ss;
 959                 socklen_t slen = sizeof(ss);
 960
 961                 freopen("/dev/null", "w", stderr);
 962
 963                 if (getpeername(0, peer, &slen))
 964                         peer = NULL;
 965
 966                 return execute(peer);
 967         }
 968
 969         if (detach)
 970                 daemonize();
 971         else
 972                 sanitize_stdfds();
 973
 974         if (pid_file)
 975                 store_pid(pid_file);
 976
 977         return serve(port, pass, gid);
 978 }