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 struct daemon_service daemon_service[] = {
 329         { "upload-pack", "uploadpack", upload_pack, 1, 1 },
 330 };
 331
 332 static void enable_service(const char *name, int ena) {
 333         int i;
 334         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 335                 if (!strcmp(daemon_service[i].name, name)) {
 336                         daemon_service[i].enabled = ena;
 337                         return;
 338                 }
 339         }
 340         die("No such service %s", name);
 341 }
 342
 343 static void make_service_overridable(const char *name, int ena) {
 344         int i;
 345         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 346                 if (!strcmp(daemon_service[i].name, name)) {
 347                         daemon_service[i].overridable = ena;
 348                         return;
 349                 }
 350         }
 351         die("No such service %s", name);
 352 }
 353
 354 static int execute(struct sockaddr *addr)
 355 {
 356         static char line[1000];
 357         int pktlen, len, i;
 358
 359         if (addr) {
 360                 char addrbuf[256] = "";
 361                 int port = -1;
 362
 363                 if (addr->sa_family == AF_INET) {
 364                         struct sockaddr_in *sin_addr = (void *) addr;
 365                         inet_ntop(addr->sa_family, &sin_addr->sin_addr, addrbuf, sizeof(addrbuf));
 366                         port = sin_addr->sin_port;
 367 #ifndef NO_IPV6
 368                 } else if (addr && addr->sa_family == AF_INET6) {
 369                         struct sockaddr_in6 *sin6_addr = (void *) addr;
 370
 371                         char *buf = addrbuf;
 372                         *buf++ = '['; *buf = '\0'; /* stpcpy() is cool */
 373                         inet_ntop(AF_INET6, &sin6_addr->sin6_addr, buf, sizeof(addrbuf) - 1);
 374                         strcat(buf, "]");
 375
 376                         port = sin6_addr->sin6_port;
 377 #endif
 378                 }
 379                 loginfo("Connection from %s:%d", addrbuf, port);
 380         }
 381
 382         alarm(init_timeout ? init_timeout : timeout);
 383         pktlen = packet_read_line(0, line, sizeof(line));
 384         alarm(0);
 385
 386         len = strlen(line);
 387         if (pktlen != len)
 388                 loginfo("Extended attributes (%d bytes) exist <%.*s>",
 389                         (int) pktlen - len,
 390                         (int) pktlen - len, line + len + 1);
 391         if (len && line[len-1] == '\n')
 392                 line[--len] = 0;
 393
 394         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 395                 struct daemon_service *s = &(daemon_service[i]);
 396                 int namelen = strlen(s->name);
 397                 if (!strncmp("git-", line, 4) &&
 398                     !strncmp(s->name, line + 4, namelen) &&
 399                     line[namelen + 4] == ' ')
 400                         return run_service(line + namelen + 5, s);
 401         }
 402
 403         logerror("Protocol error: '%s'", line);
 404         return -1;
 405 }
 406
 407
 408 /*
 409  * We count spawned/reaped separately, just to avoid any
 410  * races when updating them from signals. The SIGCHLD handler
 411  * will only update children_reaped, and the fork logic will
 412  * only update children_spawned.
 413  *
 414  * MAX_CHILDREN should be a power-of-two to make the modulus
 415  * operation cheap. It should also be at least twice
 416  * the maximum number of connections we will ever allow.
 417  */
 418 #define MAX_CHILDREN 128
 419
 420 static int max_connections = 25;
 421
 422 /* These are updated by the signal handler */
 423 static volatile unsigned int children_reaped;
 424 static pid_t dead_child[MAX_CHILDREN];
 425
 426 /* These are updated by the main loop */
 427 static unsigned int children_spawned;
 428 static unsigned int children_deleted;
 429
 430 static struct child {
 431         pid_t pid;
 432         int addrlen;
 433         struct sockaddr_storage address;
 434 } live_child[MAX_CHILDREN];
 435
 436 static void add_child(int idx, pid_t pid, struct sockaddr *addr, int addrlen)
 437 {
 438         live_child[idx].pid = pid;
 439         live_child[idx].addrlen = addrlen;
 440         memcpy(&live_child[idx].address, addr, addrlen);
 441 }
 442
 443 /*
 444  * Walk from "deleted" to "spawned", and remove child "pid".
 445  *
 446  * We move everything up by one, since the new "deleted" will
 447  * be one higher.
 448  */
 449 static void remove_child(pid_t pid, unsigned deleted, unsigned spawned)
 450 {
 451         struct child n;
 452
 453         deleted %= MAX_CHILDREN;
 454         spawned %= MAX_CHILDREN;
 455         if (live_child[deleted].pid == pid) {
 456                 live_child[deleted].pid = -1;
 457                 return;
 458         }
 459         n = live_child[deleted];
 460         for (;;) {
 461                 struct child m;
 462                 deleted = (deleted + 1) % MAX_CHILDREN;
 463                 if (deleted == spawned)
 464                         die("could not find dead child %d\n", pid);
 465                 m = live_child[deleted];
 466                 live_child[deleted] = n;
 467                 if (m.pid == pid)
 468                         return;
 469                 n = m;
 470         }
 471 }
 472
 473 /*
 474  * This gets called if the number of connections grows
 475  * past "max_connections".
 476  *
 477  * We _should_ start off by searching for connections
 478  * from the same IP, and if there is some address wth
 479  * multiple connections, we should kill that first.
 480  *
 481  * As it is, we just "randomly" kill 25% of the connections,
 482  * and our pseudo-random generator sucks too. I have no
 483  * shame.
 484  *
 485  * Really, this is just a place-holder for a _real_ algorithm.
 486  */
 487 static void kill_some_children(int signo, unsigned start, unsigned stop)
 488 {
 489         start %= MAX_CHILDREN;
 490         stop %= MAX_CHILDREN;
 491         while (start != stop) {
 492                 if (!(start & 3))
 493                         kill(live_child[start].pid, signo);
 494                 start = (start + 1) % MAX_CHILDREN;
 495         }
 496 }
 497
 498 static void check_max_connections(void)
 499 {
 500         for (;;) {
 501                 int active;
 502                 unsigned spawned, reaped, deleted;
 503
 504                 spawned = children_spawned;
 505                 reaped = children_reaped;
 506                 deleted = children_deleted;
 507
 508                 while (deleted < reaped) {
 509                         pid_t pid = dead_child[deleted % MAX_CHILDREN];
 510                         remove_child(pid, deleted, spawned);
 511                         deleted++;
 512                 }
 513                 children_deleted = deleted;
 514
 515                 active = spawned - deleted;
 516                 if (active <= max_connections)
 517                         break;
 518
 519                 /* Kill some unstarted connections with SIGTERM */
 520                 kill_some_children(SIGTERM, deleted, spawned);
 521                 if (active <= max_connections << 1)
 522                         break;
 523
 524                 /* If the SIGTERM thing isn't helping use SIGKILL */
 525                 kill_some_children(SIGKILL, deleted, spawned);
 526                 sleep(1);
 527         }
 528 }
 529
 530 static void handle(int incoming, struct sockaddr *addr, int addrlen)
 531 {
 532         pid_t pid = fork();
 533
 534         if (pid) {
 535                 unsigned idx;
 536
 537                 close(incoming);
 538                 if (pid < 0)
 539                         return;
 540
 541                 idx = children_spawned % MAX_CHILDREN;
 542                 children_spawned++;
 543                 add_child(idx, pid, addr, addrlen);
 544
 545                 check_max_connections();
 546                 return;
 547         }
 548
 549         dup2(incoming, 0);
 550         dup2(incoming, 1);
 551         close(incoming);
 552
 553         exit(execute(addr));
 554 }
 555
 556 static void child_handler(int signo)
 557 {
 558         for (;;) {
 559                 int status;
 560                 pid_t pid = waitpid(-1, &status, WNOHANG);
 561
 562                 if (pid > 0) {
 563                         unsigned reaped = children_reaped;
 564                         dead_child[reaped % MAX_CHILDREN] = pid;
 565                         children_reaped = reaped + 1;
 566                         /* XXX: Custom logging, since we don't wanna getpid() */
 567                         if (verbose) {
 568                                 const char *dead = "";
 569                                 if (!WIFEXITED(status) || WEXITSTATUS(status) > 0)
 570                                         dead = " (with error)";
 571                                 if (log_syslog)
 572                                         syslog(LOG_INFO, "[%d] Disconnected%s", pid, dead);
 573                                 else
 574                                         fprintf(stderr, "[%d] Disconnected%s\n", pid, dead);
 575                         }
 576                         continue;
 577                 }
 578                 break;
 579         }
 580 }
 581
 582 static int set_reuse_addr(int sockfd)
 583 {
 584         int on = 1;
 585
 586         if (!reuseaddr)
 587                 return 0;
 588         return setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
 589                           &on, sizeof(on));
 590 }
 591
 592 #ifndef NO_IPV6
 593
 594 static int socksetup(int port, int **socklist_p)
 595 {
 596         int socknum = 0, *socklist = NULL;
 597         int maxfd = -1;
 598         char pbuf[NI_MAXSERV];
 599
 600         struct addrinfo hints, *ai0, *ai;
 601         int gai;
 602
 603         sprintf(pbuf, "%d", port);
 604         memset(&hints, 0, sizeof(hints));
 605         hints.ai_family = AF_UNSPEC;
 606         hints.ai_socktype = SOCK_STREAM;
 607         hints.ai_protocol = IPPROTO_TCP;
 608         hints.ai_flags = AI_PASSIVE;
 609
 610         gai = getaddrinfo(NULL, pbuf, &hints, &ai0);
 611         if (gai)
 612                 die("getaddrinfo() failed: %s\n", gai_strerror(gai));
 613
 614         for (ai = ai0; ai; ai = ai->ai_next) {
 615                 int sockfd;
 616
 617                 sockfd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
 618                 if (sockfd < 0)
 619                         continue;
 620                 if (sockfd >= FD_SETSIZE) {
 621                         error("too large socket descriptor.");
 622                         close(sockfd);
 623                         continue;
 624                 }
 625
 626 #ifdef IPV6_V6ONLY
 627                 if (ai->ai_family == AF_INET6) {
 628                         int on = 1;
 629                         setsockopt(sockfd, IPPROTO_IPV6, IPV6_V6ONLY,
 630                                    &on, sizeof(on));
 631                         /* Note: error is not fatal */
 632                 }
 633 #endif
 634
 635                 if (set_reuse_addr(sockfd)) {
 636                         close(sockfd);
 637                         continue;
 638                 }
 639
 640                 if (bind(sockfd, ai->ai_addr, ai->ai_addrlen) < 0) {
 641                         close(sockfd);
 642                         continue;       /* not fatal */
 643                 }
 644                 if (listen(sockfd, 5) < 0) {
 645                         close(sockfd);
 646                         continue;       /* not fatal */
 647                 }
 648
 649                 socklist = xrealloc(socklist, sizeof(int) * (socknum + 1));
 650                 socklist[socknum++] = sockfd;
 651
 652                 if (maxfd < sockfd)
 653                         maxfd = sockfd;
 654         }
 655
 656         freeaddrinfo(ai0);
 657
 658         *socklist_p = socklist;
 659         return socknum;
 660 }
 661
 662 #else /* NO_IPV6 */
 663
 664 static int socksetup(int port, int **socklist_p)
 665 {
 666         struct sockaddr_in sin;
 667         int sockfd;
 668
 669         sockfd = socket(AF_INET, SOCK_STREAM, 0);
 670         if (sockfd < 0)
 671                 return 0;
 672
 673         memset(&sin, 0, sizeof sin);
 674         sin.sin_family = AF_INET;
 675         sin.sin_addr.s_addr = htonl(INADDR_ANY);
 676         sin.sin_port = htons(port);
 677
 678         if (set_reuse_addr(sockfd)) {
 679                 close(sockfd);
 680                 return 0;
 681         }
 682
 683         if ( bind(sockfd, (struct sockaddr *)&sin, sizeof sin) < 0 ) {
 684                 close(sockfd);
 685                 return 0;
 686         }
 687
 688         if (listen(sockfd, 5) < 0) {
 689                 close(sockfd);
 690                 return 0;
 691         }
 692
 693         *socklist_p = xmalloc(sizeof(int));
 694         **socklist_p = sockfd;
 695         return 1;
 696 }
 697
 698 #endif
 699
 700 static int service_loop(int socknum, int *socklist)
 701 {
 702         struct pollfd *pfd;
 703         int i;
 704
 705         pfd = xcalloc(socknum, sizeof(struct pollfd));
 706
 707         for (i = 0; i < socknum; i++) {
 708                 pfd[i].fd = socklist[i];
 709                 pfd[i].events = POLLIN;
 710         }
 711
 712         signal(SIGCHLD, child_handler);
 713
 714         for (;;) {
 715                 int i;
 716
 717                 if (poll(pfd, socknum, -1) < 0) {
 718                         if (errno != EINTR) {
 719                                 error("poll failed, resuming: %s",
 720                                       strerror(errno));
 721                                 sleep(1);
 722                         }
 723                         continue;
 724                 }
 725
 726                 for (i = 0; i < socknum; i++) {
 727                         if (pfd[i].revents & POLLIN) {
 728                                 struct sockaddr_storage ss;
 729                                 unsigned int sslen = sizeof(ss);
 730                                 int incoming = accept(pfd[i].fd, (struct sockaddr *)&ss, &sslen);
 731                                 if (incoming < 0) {
 732                                         switch (errno) {
 733                                         case EAGAIN:
 734                                         case EINTR:
 735                                         case ECONNABORTED:
 736                                                 continue;
 737                                         default:
 738                                                 die("accept returned %s", strerror(errno));
 739                                         }
 740                                 }
 741                                 handle(incoming, (struct sockaddr *)&ss, sslen);
 742                         }
 743                 }
 744         }
 745 }
 746
 747 /* if any standard file descriptor is missing open it to /dev/null */
 748 static void sanitize_stdfds(void)
 749 {
 750         int fd = open("/dev/null", O_RDWR, 0);
 751         while (fd != -1 && fd < 2)
 752                 fd = dup(fd);
 753         if (fd == -1)
 754                 die("open /dev/null or dup failed: %s", strerror(errno));
 755         if (fd > 2)
 756                 close(fd);
 757 }
 758
 759 static void daemonize(void)
 760 {
 761         switch (fork()) {
 762                 case 0:
 763                         break;
 764                 case -1:
 765                         die("fork failed: %s", strerror(errno));
 766                 default:
 767                         exit(0);
 768         }
 769         if (setsid() == -1)
 770                 die("setsid failed: %s", strerror(errno));
 771         close(0);
 772         close(1);
 773         close(2);
 774         sanitize_stdfds();
 775 }
 776
 777 static void store_pid(const char *path)
 778 {
 779         FILE *f = fopen(path, "w");
 780         if (!f)
 781                 die("cannot open pid file %s: %s", path, strerror(errno));
 782         fprintf(f, "%d\n", getpid());
 783         fclose(f);
 784 }
 785
 786 static int serve(int port, struct passwd *pass, gid_t gid)
 787 {
 788         int socknum, *socklist;
 789
 790         socknum = socksetup(port, &socklist);
 791         if (socknum == 0)
 792                 die("unable to allocate any listen sockets on port %u", port);
 793
 794         if (pass && gid &&
 795             (initgroups(pass->pw_name, gid) || setgid (gid) ||
 796              setuid(pass->pw_uid)))
 797                 die("cannot drop privileges");
 798
 799         return service_loop(socknum, socklist);
 800 }
 801
 802 int main(int argc, char **argv)
 803 {
 804         int port = DEFAULT_GIT_PORT;
 805         int inetd_mode = 0;
 806         const char *pid_file = NULL, *user_name = NULL, *group_name = NULL;
 807         int detach = 0;
 808         struct passwd *pass = NULL;
 809         struct group *group;
 810         gid_t gid = 0;
 811         int i;
 812
 813         /* Without this we cannot rely on waitpid() to tell
 814          * what happened to our children.
 815          */
 816         signal(SIGCHLD, SIG_DFL);
 817
 818         for (i = 1; i < argc; i++) {
 819                 char *arg = argv[i];
 820
 821                 if (!strncmp(arg, "--port=", 7)) {
 822                         char *end;
 823                         unsigned long n;
 824                         n = strtoul(arg+7, &end, 0);
 825                         if (arg[7] && !*end) {
 826                                 port = n;
 827                                 continue;
 828                         }
 829                 }
 830                 if (!strcmp(arg, "--inetd")) {
 831                         inetd_mode = 1;
 832                         log_syslog = 1;
 833                         continue;
 834                 }
 835                 if (!strcmp(arg, "--verbose")) {
 836                         verbose = 1;
 837                         continue;
 838                 }
 839                 if (!strcmp(arg, "--syslog")) {
 840                         log_syslog = 1;
 841                         continue;
 842                 }
 843                 if (!strcmp(arg, "--export-all")) {
 844                         export_all_trees = 1;
 845                         continue;
 846                 }
 847                 if (!strncmp(arg, "--timeout=", 10)) {
 848                         timeout = atoi(arg+10);
 849                         continue;
 850                 }
 851                 if (!strncmp(arg, "--init-timeout=", 15)) {
 852                         init_timeout = atoi(arg+15);
 853                         continue;
 854                 }
 855                 if (!strcmp(arg, "--strict-paths")) {
 856                         strict_paths = 1;
 857                         continue;
 858                 }
 859                 if (!strncmp(arg, "--base-path=", 12)) {
 860                         base_path = arg+12;
 861                         continue;
 862                 }
 863                 if (!strcmp(arg, "--reuseaddr")) {
 864                         reuseaddr = 1;
 865                         continue;
 866                 }
 867                 if (!strcmp(arg, "--user-path")) {
 868                         user_path = "";
 869                         continue;
 870                 }
 871                 if (!strncmp(arg, "--user-path=", 12)) {
 872                         user_path = arg + 12;
 873                         continue;
 874                 }
 875                 if (!strncmp(arg, "--pid-file=", 11)) {
 876                         pid_file = arg + 11;
 877                         continue;
 878                 }
 879                 if (!strcmp(arg, "--detach")) {
 880                         detach = 1;
 881                         log_syslog = 1;
 882                         continue;
 883                 }
 884                 if (!strncmp(arg, "--user=", 7)) {
 885                         user_name = arg + 7;
 886                         continue;
 887                 }
 888                 if (!strncmp(arg, "--group=", 8)) {
 889                         group_name = arg + 8;
 890                         continue;
 891                 }
 892                 if (!strncmp(arg, "--enable=", 9)) {
 893                         enable_service(arg + 9, 1);
 894                         continue;
 895                 }
 896                 if (!strncmp(arg, "--disable=", 10)) {
 897                         enable_service(arg + 10, 0);
 898                         continue;
 899                 }
 900                 if (!strncmp(arg, "--allow-override=", 17)) {
 901                         make_service_overridable(arg + 17, 1);
 902                         continue;
 903                 }
 904                 if (!strncmp(arg, "--forbid-override=", 18)) {
 905                         make_service_overridable(arg + 18, 0);
 906                         continue;
 907                 }
 908                 if (!strcmp(arg, "--")) {
 909                         ok_paths = &argv[i+1];
 910                         break;
 911                 } else if (arg[0] != '-') {
 912                         ok_paths = &argv[i];
 913                         break;
 914                 }
 915
 916                 usage(daemon_usage);
 917         }
 918
 919         if (inetd_mode && (group_name || user_name))
 920                 die("--user and --group are incompatible with --inetd");
 921
 922         if (group_name && !user_name)
 923                 die("--group supplied without --user");
 924
 925         if (user_name) {
 926                 pass = getpwnam(user_name);
 927                 if (!pass)
 928                         die("user not found - %s", user_name);
 929
 930                 if (!group_name)
 931                         gid = pass->pw_gid;
 932                 else {
 933                         group = getgrnam(group_name);
 934                         if (!group)
 935                                 die("group not found - %s", group_name);
 936
 937                         gid = group->gr_gid;
 938                 }
 939         }
 940
 941         if (log_syslog) {
 942                 openlog("git-daemon", 0, LOG_DAEMON);
 943                 set_die_routine(daemon_die);
 944         }
 945
 946         if (strict_paths && (!ok_paths || !*ok_paths))
 947                 die("option --strict-paths requires a whitelist");
 948
 949         if (inetd_mode) {
 950                 struct sockaddr_storage ss;
 951                 struct sockaddr *peer = (struct sockaddr *)&ss;
 952                 socklen_t slen = sizeof(ss);
 953
 954                 freopen("/dev/null", "w", stderr);
 955
 956                 if (getpeername(0, peer, &slen))
 957                         peer = NULL;
 958
 959                 return execute(peer);
 960         }
 961
 962         if (detach)
 963                 daemonize();
 964         else
 965                 sanitize_stdfds();
 966
 967         if (pid_file)
 968                 store_pid(pid_file);
 969
 970         return serve(port, pass, gid);
 971 }