daemon.c

   1 #include "cache.h"
   2 #include "pkt-line.h"
   3 #include "exec_cmd.h"
   4 #include "interpolate.h"
   5
   6 #include <syslog.h>
   7
   8 #ifndef HOST_NAME_MAX
   9 #define HOST_NAME_MAX 256
  10 #endif
  11
  12 #ifndef NI_MAXSERV
  13 #define NI_MAXSERV 32
  14 #endif
  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] [--export-all]\n"
  22 "           [--timeout=n] [--init-timeout=n] [--max-connections=n]\n"
  23 "           [--strict-paths] [--base-path=path] [--base-path-relaxed]\n"
  24 "           [--user-path | --user-path=path]\n"
  25 "           [--interpolated-path=path]\n"
  26 "           [--reuseaddr] [--detach] [--pid-file=file]\n"
  27 "           [--[enable|disable|allow-override|forbid-override]=service]\n"
  28 "           [--inetd | [--listen=host_or_ipaddr] [--port=n]\n"
  29 "                      [--user=user [--group=group]]\n"
  30 "           [directory...]";
  31
  32 /* List of acceptable pathname prefixes */
  33 static char **ok_paths;
  34 static int strict_paths;
  35
  36 /* If this is set, git-daemon-export-ok is not required */
  37 static int export_all_trees;
  38
  39 /* Take all paths relative to this one if non-NULL */
  40 static char *base_path;
  41 static char *interpolated_path;
  42 static int base_path_relaxed;
  43
  44 /* Flag indicating client sent extra args. */
  45 static int saw_extended_args;
  46
  47 /* If defined, ~user notation is allowed and the string is inserted
  48  * after ~user/.  E.g. a request to git://host/~alice/frotz would
  49  * go to /home/alice/pub_git/frotz with --user-path=pub_git.
  50  */
  51 static const char *user_path;
  52
  53 /* Timeout, and initial timeout */
  54 static unsigned int timeout;
  55 static unsigned int init_timeout;
  56
  57 /*
  58  * Static table for now.  Ugh.
  59  * Feel free to make dynamic as needed.
  60  */
  61 #define INTERP_SLOT_HOST        (0)
  62 #define INTERP_SLOT_CANON_HOST  (1)
  63 #define INTERP_SLOT_IP          (2)
  64 #define INTERP_SLOT_PORT        (3)
  65 #define INTERP_SLOT_DIR         (4)
  66 #define INTERP_SLOT_PERCENT     (5)
  67
  68 static struct interp interp_table[] = {
  69         { "%H", 0},
  70         { "%CH", 0},
  71         { "%IP", 0},
  72         { "%P", 0},
  73         { "%D", 0},
  74         { "%%", 0},
  75 };
  76
  77
  78 static void logreport(int priority, const char *err, va_list params)
  79 {
  80         if (log_syslog) {
  81                 char buf[1024];
  82                 vsnprintf(buf, sizeof(buf), err, params);
  83                 syslog(priority, "%s", buf);
  84         } else {
  85                 /*
  86                  * Since stderr is set to linebuffered mode, the
  87                  * logging of different processes will not overlap
  88                  */
  89                 fprintf(stderr, "[%"PRIuMAX"] ", (uintmax_t)getpid());
  90                 vfprintf(stderr, err, params);
  91                 fputc('\n', stderr);
  92         }
  93 }
  94
  95 static void logerror(const char *err, ...)
  96 {
  97         va_list params;
  98         va_start(params, err);
  99         logreport(LOG_ERR, err, params);
 100         va_end(params);
 101 }
 102
 103 static void loginfo(const char *err, ...)
 104 {
 105         va_list params;
 106         if (!verbose)
 107                 return;
 108         va_start(params, err);
 109         logreport(LOG_INFO, err, params);
 110         va_end(params);
 111 }
 112
 113 static void NORETURN daemon_die(const char *err, va_list params)
 114 {
 115         logreport(LOG_ERR, err, params);
 116         exit(1);
 117 }
 118
 119 static int avoid_alias(char *p)
 120 {
 121         int sl, ndot;
 122
 123         /*
 124          * This resurrects the belts and suspenders paranoia check by HPA
 125          * done in <435560F7.4080006@zytor.com> thread, now enter_repo()
 126          * does not do getcwd() based path canonicalizations.
 127          *
 128          * sl becomes true immediately after seeing '/' and continues to
 129          * be true as long as dots continue after that without intervening
 130          * non-dot character.
 131          */
 132         if (!p || (*p != '/' && *p != '~'))
 133                 return -1;
 134         sl = 1; ndot = 0;
 135         p++;
 136
 137         while (1) {
 138                 char ch = *p++;
 139                 if (sl) {
 140                         if (ch == '.')
 141                                 ndot++;
 142                         else if (ch == '/') {
 143                                 if (ndot < 3)
 144                                         /* reject //, /./ and /../ */
 145                                         return -1;
 146                                 ndot = 0;
 147                         }
 148                         else if (ch == 0) {
 149                                 if (0 < ndot && ndot < 3)
 150                                         /* reject /.$ and /..$ */
 151                                         return -1;
 152                                 return 0;
 153                         }
 154                         else
 155                                 sl = ndot = 0;
 156                 }
 157                 else if (ch == 0)
 158                         return 0;
 159                 else if (ch == '/') {
 160                         sl = 1;
 161                         ndot = 0;
 162                 }
 163         }
 164 }
 165
 166 static char *path_ok(struct interp *itable)
 167 {
 168         static char rpath[PATH_MAX];
 169         static char interp_path[PATH_MAX];
 170         int retried_path = 0;
 171         char *path;
 172         char *dir;
 173
 174         dir = itable[INTERP_SLOT_DIR].value;
 175
 176         if (avoid_alias(dir)) {
 177                 logerror("'%s': aliased", dir);
 178                 return NULL;
 179         }
 180
 181         if (*dir == '~') {
 182                 if (!user_path) {
 183                         logerror("'%s': User-path not allowed", dir);
 184                         return NULL;
 185                 }
 186                 if (*user_path) {
 187                         /* Got either "~alice" or "~alice/foo";
 188                          * rewrite them to "~alice/%s" or
 189                          * "~alice/%s/foo".
 190                          */
 191                         int namlen, restlen = strlen(dir);
 192                         char *slash = strchr(dir, '/');
 193                         if (!slash)
 194                                 slash = dir + restlen;
 195                         namlen = slash - dir;
 196                         restlen -= namlen;
 197                         loginfo("userpath <%s>, request <%s>, namlen %d, restlen %d, slash <%s>", user_path, dir, namlen, restlen, slash);
 198                         snprintf(rpath, PATH_MAX, "%.*s/%s%.*s",
 199                                  namlen, dir, user_path, restlen, slash);
 200                         dir = rpath;
 201                 }
 202         }
 203         else if (interpolated_path && saw_extended_args) {
 204                 if (*dir != '/') {
 205                         /* Allow only absolute */
 206                         logerror("'%s': Non-absolute path denied (interpolated-path active)", dir);
 207                         return NULL;
 208                 }
 209
 210                 interpolate(interp_path, PATH_MAX, interpolated_path,
 211                             interp_table, ARRAY_SIZE(interp_table));
 212                 loginfo("Interpolated dir '%s'", interp_path);
 213
 214                 dir = interp_path;
 215         }
 216         else if (base_path) {
 217                 if (*dir != '/') {
 218                         /* Allow only absolute */
 219                         logerror("'%s': Non-absolute path denied (base-path active)", dir);
 220                         return NULL;
 221                 }
 222                 snprintf(rpath, PATH_MAX, "%s%s", base_path, dir);
 223                 dir = rpath;
 224         }
 225
 226         do {
 227                 path = enter_repo(dir, strict_paths);
 228                 if (path)
 229                         break;
 230
 231                 /*
 232                  * if we fail and base_path_relaxed is enabled, try without
 233                  * prefixing the base path
 234                  */
 235                 if (base_path && base_path_relaxed && !retried_path) {
 236                         dir = itable[INTERP_SLOT_DIR].value;
 237                         retried_path = 1;
 238                         continue;
 239                 }
 240                 break;
 241         } while (1);
 242
 243         if (!path) {
 244                 logerror("'%s': unable to chdir or not a git archive", dir);
 245                 return NULL;
 246         }
 247
 248         if ( ok_paths && *ok_paths ) {
 249                 char **pp;
 250                 int pathlen = strlen(path);
 251
 252                 /* The validation is done on the paths after enter_repo
 253                  * appends optional {.git,.git/.git} and friends, but
 254                  * it does not use getcwd().  So if your /pub is
 255                  * a symlink to /mnt/pub, you can whitelist /pub and
 256                  * do not have to say /mnt/pub.
 257                  * Do not say /pub/.
 258                  */
 259                 for ( pp = ok_paths ; *pp ; pp++ ) {
 260                         int len = strlen(*pp);
 261                         if (len <= pathlen &&
 262                             !memcmp(*pp, path, len) &&
 263                             (path[len] == '\0' ||
 264                              (!strict_paths && path[len] == '/')))
 265                                 return path;
 266                 }
 267         }
 268         else {
 269                 /* be backwards compatible */
 270                 if (!strict_paths)
 271                         return path;
 272         }
 273
 274         logerror("'%s': not in whitelist", path);
 275         return NULL;            /* Fallthrough. Deny by default */
 276 }
 277
 278 typedef int (*daemon_service_fn)(void);
 279 struct daemon_service {
 280         const char *name;
 281         const char *config_name;
 282         daemon_service_fn fn;
 283         int enabled;
 284         int overridable;
 285 };
 286
 287 static struct daemon_service *service_looking_at;
 288 static int service_enabled;
 289
 290 static int git_daemon_config(const char *var, const char *value, void *cb)
 291 {
 292         if (!prefixcmp(var, "daemon.") &&
 293             !strcmp(var + 7, service_looking_at->config_name)) {
 294                 service_enabled = git_config_bool(var, value);
 295                 return 0;
 296         }
 297
 298         /* we are not interested in parsing any other configuration here */
 299         return 0;
 300 }
 301
 302 static int run_service(struct interp *itable, struct daemon_service *service)
 303 {
 304         const char *path;
 305         int enabled = service->enabled;
 306
 307         loginfo("Request %s for '%s'",
 308                 service->name,
 309                 itable[INTERP_SLOT_DIR].value);
 310
 311         if (!enabled && !service->overridable) {
 312                 logerror("'%s': service not enabled.", service->name);
 313                 errno = EACCES;
 314                 return -1;
 315         }
 316
 317         if (!(path = path_ok(itable)))
 318                 return -1;
 319
 320         /*
 321          * Security on the cheap.
 322          *
 323          * We want a readable HEAD, usable "objects" directory, and
 324          * a "git-daemon-export-ok" flag that says that the other side
 325          * is ok with us doing this.
 326          *
 327          * path_ok() uses enter_repo() and does whitelist checking.
 328          * We only need to make sure the repository is exported.
 329          */
 330
 331         if (!export_all_trees && access("git-daemon-export-ok", F_OK)) {
 332                 logerror("'%s': repository not exported.", path);
 333                 errno = EACCES;
 334                 return -1;
 335         }
 336
 337         if (service->overridable) {
 338                 service_looking_at = service;
 339                 service_enabled = -1;
 340                 git_config(git_daemon_config, NULL);
 341                 if (0 <= service_enabled)
 342                         enabled = service_enabled;
 343         }
 344         if (!enabled) {
 345                 logerror("'%s': service not enabled for '%s'",
 346                          service->name, path);
 347                 errno = EACCES;
 348                 return -1;
 349         }
 350
 351         /*
 352          * We'll ignore SIGTERM from now on, we have a
 353          * good client.
 354          */
 355         signal(SIGTERM, SIG_IGN);
 356
 357         return service->fn();
 358 }
 359
 360 static int upload_pack(void)
 361 {
 362         /* Timeout as string */
 363         char timeout_buf[64];
 364
 365         snprintf(timeout_buf, sizeof timeout_buf, "--timeout=%u", timeout);
 366
 367         /* git-upload-pack only ever reads stuff, so this is safe */
 368         execl_git_cmd("upload-pack", "--strict", timeout_buf, ".", NULL);
 369         return -1;
 370 }
 371
 372 static int upload_archive(void)
 373 {
 374         execl_git_cmd("upload-archive", ".", NULL);
 375         return -1;
 376 }
 377
 378 static int receive_pack(void)
 379 {
 380         execl_git_cmd("receive-pack", ".", NULL);
 381         return -1;
 382 }
 383
 384 static struct daemon_service daemon_service[] = {
 385         { "upload-archive", "uploadarch", upload_archive, 0, 1 },
 386         { "upload-pack", "uploadpack", upload_pack, 1, 1 },
 387         { "receive-pack", "receivepack", receive_pack, 0, 1 },
 388 };
 389
 390 static void enable_service(const char *name, int ena)
 391 {
 392         int i;
 393         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 394                 if (!strcmp(daemon_service[i].name, name)) {
 395                         daemon_service[i].enabled = ena;
 396                         return;
 397                 }
 398         }
 399         die("No such service %s", name);
 400 }
 401
 402 static void make_service_overridable(const char *name, int ena)
 403 {
 404         int i;
 405         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 406                 if (!strcmp(daemon_service[i].name, name)) {
 407                         daemon_service[i].overridable = ena;
 408                         return;
 409                 }
 410         }
 411         die("No such service %s", name);
 412 }
 413
 414 /*
 415  * Separate the "extra args" information as supplied by the client connection.
 416  * Any resulting data is squirreled away in the given interpolation table.
 417  */
 418 static void parse_extra_args(struct interp *table, char *extra_args, int buflen)
 419 {
 420         char *val;
 421         int vallen;
 422         char *end = extra_args + buflen;
 423
 424         while (extra_args < end && *extra_args) {
 425                 saw_extended_args = 1;
 426                 if (strncasecmp("host=", extra_args, 5) == 0) {
 427                         val = extra_args + 5;
 428                         vallen = strlen(val) + 1;
 429                         if (*val) {
 430                                 /* Split <host>:<port> at colon. */
 431                                 char *host = val;
 432                                 char *port = strrchr(host, ':');
 433                                 if (port) {
 434                                         *port = 0;
 435                                         port++;
 436                                         interp_set_entry(table, INTERP_SLOT_PORT, port);
 437                                 }
 438                                 interp_set_entry(table, INTERP_SLOT_HOST, host);
 439                         }
 440
 441                         /* On to the next one */
 442                         extra_args = val + vallen;
 443                 }
 444         }
 445 }
 446
 447 static void fill_in_extra_table_entries(struct interp *itable)
 448 {
 449         char *hp;
 450
 451         /*
 452          * Replace literal host with lowercase-ized hostname.
 453          */
 454         hp = interp_table[INTERP_SLOT_HOST].value;
 455         if (!hp)
 456                 return;
 457         for ( ; *hp; hp++)
 458                 *hp = tolower(*hp);
 459
 460         /*
 461          * Locate canonical hostname and its IP address.
 462          */
 463 #ifndef NO_IPV6
 464         {
 465                 struct addrinfo hints;
 466                 struct addrinfo *ai, *ai0;
 467                 int gai;
 468                 static char addrbuf[HOST_NAME_MAX + 1];
 469
 470                 memset(&hints, 0, sizeof(hints));
 471                 hints.ai_flags = AI_CANONNAME;
 472
 473                 gai = getaddrinfo(interp_table[INTERP_SLOT_HOST].value, 0, &hints, &ai0);
 474                 if (!gai) {
 475                         for (ai = ai0; ai; ai = ai->ai_next) {
 476                                 struct sockaddr_in *sin_addr = (void *)ai->ai_addr;
 477
 478                                 inet_ntop(AF_INET, &sin_addr->sin_addr,
 479                                           addrbuf, sizeof(addrbuf));
 480                                 interp_set_entry(interp_table,
 481                                                  INTERP_SLOT_CANON_HOST, ai->ai_canonname);
 482                                 interp_set_entry(interp_table,
 483                                                  INTERP_SLOT_IP, addrbuf);
 484                                 break;
 485                         }
 486                         freeaddrinfo(ai0);
 487                 }
 488         }
 489 #else
 490         {
 491                 struct hostent *hent;
 492                 struct sockaddr_in sa;
 493                 char **ap;
 494                 static char addrbuf[HOST_NAME_MAX + 1];
 495
 496                 hent = gethostbyname(interp_table[INTERP_SLOT_HOST].value);
 497
 498                 ap = hent->h_addr_list;
 499                 memset(&sa, 0, sizeof sa);
 500                 sa.sin_family = hent->h_addrtype;
 501                 sa.sin_port = htons(0);
 502                 memcpy(&sa.sin_addr, *ap, hent->h_length);
 503
 504                 inet_ntop(hent->h_addrtype, &sa.sin_addr,
 505                           addrbuf, sizeof(addrbuf));
 506
 507                 interp_set_entry(interp_table, INTERP_SLOT_CANON_HOST, hent->h_name);
 508                 interp_set_entry(interp_table, INTERP_SLOT_IP, addrbuf);
 509         }
 510 #endif
 511 }
 512
 513
 514 static int execute(struct sockaddr *addr)
 515 {
 516         static char line[1000];
 517         int pktlen, len, i;
 518
 519         if (addr) {
 520                 char addrbuf[256] = "";
 521                 int port = -1;
 522
 523                 if (addr->sa_family == AF_INET) {
 524                         struct sockaddr_in *sin_addr = (void *) addr;
 525                         inet_ntop(addr->sa_family, &sin_addr->sin_addr, addrbuf, sizeof(addrbuf));
 526                         port = ntohs(sin_addr->sin_port);
 527 #ifndef NO_IPV6
 528                 } else if (addr && addr->sa_family == AF_INET6) {
 529                         struct sockaddr_in6 *sin6_addr = (void *) addr;
 530
 531                         char *buf = addrbuf;
 532                         *buf++ = '['; *buf = '\0'; /* stpcpy() is cool */
 533                         inet_ntop(AF_INET6, &sin6_addr->sin6_addr, buf, sizeof(addrbuf) - 1);
 534                         strcat(buf, "]");
 535
 536                         port = ntohs(sin6_addr->sin6_port);
 537 #endif
 538                 }
 539                 loginfo("Connection from %s:%d", addrbuf, port);
 540                 setenv("REMOTE_ADDR", addrbuf, 1);
 541         }
 542         else {
 543                 unsetenv("REMOTE_ADDR");
 544         }
 545
 546         alarm(init_timeout ? init_timeout : timeout);
 547         pktlen = packet_read_line(0, line, sizeof(line));
 548         alarm(0);
 549
 550         len = strlen(line);
 551         if (pktlen != len)
 552                 loginfo("Extended attributes (%d bytes) exist <%.*s>",
 553                         (int) pktlen - len,
 554                         (int) pktlen - len, line + len + 1);
 555         if (len && line[len-1] == '\n') {
 556                 line[--len] = 0;
 557                 pktlen--;
 558         }
 559
 560         /*
 561          * Initialize the path interpolation table for this connection.
 562          */
 563         interp_clear_table(interp_table, ARRAY_SIZE(interp_table));
 564         interp_set_entry(interp_table, INTERP_SLOT_PERCENT, "%");
 565
 566         if (len != pktlen) {
 567             parse_extra_args(interp_table, line + len + 1, pktlen - len - 1);
 568             fill_in_extra_table_entries(interp_table);
 569         }
 570
 571         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 572                 struct daemon_service *s = &(daemon_service[i]);
 573                 int namelen = strlen(s->name);
 574                 if (!prefixcmp(line, "git-") &&
 575                     !strncmp(s->name, line + 4, namelen) &&
 576                     line[namelen + 4] == ' ') {
 577                         /*
 578                          * Note: The directory here is probably context sensitive,
 579                          * and might depend on the actual service being performed.
 580                          */
 581                         interp_set_entry(interp_table,
 582                                          INTERP_SLOT_DIR, line + namelen + 5);
 583                         return run_service(interp_table, s);
 584                 }
 585         }
 586
 587         logerror("Protocol error: '%s'", line);
 588         return -1;
 589 }
 590
 591 static int max_connections = 32;
 592
 593 static unsigned int live_children;
 594
 595 static struct child {
 596         struct child *next;
 597         pid_t pid;
 598         struct sockaddr_storage address;
 599 } *firstborn;
 600
 601 static void add_child(pid_t pid, struct sockaddr *addr, int addrlen)
 602 {
 603         struct child *newborn, **cradle;
 604
 605         /*
 606          * This must be xcalloc() -- we'll compare the whole sockaddr_storage
 607          * but individual address may be shorter.
 608          */
 609         newborn = xcalloc(1, sizeof(*newborn));
 610         live_children++;
 611         newborn->pid = pid;
 612         memcpy(&newborn->address, addr, addrlen);
 613         for (cradle = &firstborn; *cradle; cradle = &(*cradle)->next)
 614                 if (!memcmp(&(*cradle)->address, &newborn->address,
 615                             sizeof(newborn->address)))
 616                         break;
 617         newborn->next = *cradle;
 618         *cradle = newborn;
 619 }
 620
 621 static void remove_child(pid_t pid)
 622 {
 623         struct child **cradle, *blanket;
 624
 625         for (cradle = &firstborn; (blanket = *cradle); cradle = &blanket->next)
 626                 if (blanket->pid == pid) {
 627                         *cradle = blanket->next;
 628                         live_children--;
 629                         free(blanket);
 630                         break;
 631                 }
 632 }
 633
 634 /*
 635  * This gets called if the number of connections grows
 636  * past "max_connections".
 637  *
 638  * We kill the newest connection from a duplicate IP.
 639  */
 640 static void kill_some_child(void)
 641 {
 642         const struct child *blanket, *next;
 643
 644         if (!(blanket = firstborn))
 645                 return;
 646
 647         for (; (next = blanket->next); blanket = next)
 648                 if (!memcmp(&blanket->address, &next->address,
 649                             sizeof(next->address))) {
 650                         kill(blanket->pid, SIGTERM);
 651                         break;
 652                 }
 653 }
 654
 655 static void check_dead_children(void)
 656 {
 657         int status;
 658         pid_t pid;
 659
 660         while ((pid = waitpid(-1, &status, WNOHANG)) > 0) {
 661                 const char *dead = "";
 662                 remove_child(pid);
 663                 if (!WIFEXITED(status) || (WEXITSTATUS(status) > 0))
 664                         dead = " (with error)";
 665                 loginfo("[%"PRIuMAX"] Disconnected%s", (uintmax_t)pid, dead);
 666         }
 667 }
 668
 669 static void handle(int incoming, struct sockaddr *addr, int addrlen)
 670 {
 671         pid_t pid;
 672
 673         if (max_connections && live_children >= max_connections) {
 674                 kill_some_child();
 675                 sleep(1);  /* give it some time to die */
 676                 check_dead_children();
 677                 if (live_children >= max_connections) {
 678                         close(incoming);
 679                         logerror("Too many children, dropping connection");
 680                         return;
 681                 }
 682         }
 683
 684         if ((pid = fork())) {
 685                 close(incoming);
 686                 if (pid < 0) {
 687                         logerror("Couldn't fork %s", strerror(errno));
 688                         return;
 689                 }
 690
 691                 add_child(pid, addr, addrlen);
 692                 return;
 693         }
 694
 695         dup2(incoming, 0);
 696         dup2(incoming, 1);
 697         close(incoming);
 698
 699         exit(execute(addr));
 700 }
 701
 702 static void child_handler(int signo)
 703 {
 704         /*
 705          * Otherwise empty handler because systemcalls will get interrupted
 706          * upon signal receipt
 707          * SysV needs the handler to be rearmed
 708          */
 709         signal(SIGCHLD, child_handler);
 710 }
 711
 712 static int set_reuse_addr(int sockfd)
 713 {
 714         int on = 1;
 715
 716         if (!reuseaddr)
 717                 return 0;
 718         return setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
 719                           &on, sizeof(on));
 720 }
 721
 722 #ifndef NO_IPV6
 723
 724 static int socksetup(char *listen_addr, int listen_port, int **socklist_p)
 725 {
 726         int socknum = 0, *socklist = NULL;
 727         int maxfd = -1;
 728         char pbuf[NI_MAXSERV];
 729         struct addrinfo hints, *ai0, *ai;
 730         int gai;
 731         long flags;
 732
 733         sprintf(pbuf, "%d", listen_port);
 734         memset(&hints, 0, sizeof(hints));
 735         hints.ai_family = AF_UNSPEC;
 736         hints.ai_socktype = SOCK_STREAM;
 737         hints.ai_protocol = IPPROTO_TCP;
 738         hints.ai_flags = AI_PASSIVE;
 739
 740         gai = getaddrinfo(listen_addr, pbuf, &hints, &ai0);
 741         if (gai)
 742                 die("getaddrinfo() failed: %s\n", gai_strerror(gai));
 743
 744         for (ai = ai0; ai; ai = ai->ai_next) {
 745                 int sockfd;
 746
 747                 sockfd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
 748                 if (sockfd < 0)
 749                         continue;
 750                 if (sockfd >= FD_SETSIZE) {
 751                         logerror("Socket descriptor too large");
 752                         close(sockfd);
 753                         continue;
 754                 }
 755
 756 #ifdef IPV6_V6ONLY
 757                 if (ai->ai_family == AF_INET6) {
 758                         int on = 1;
 759                         setsockopt(sockfd, IPPROTO_IPV6, IPV6_V6ONLY,
 760                                    &on, sizeof(on));
 761                         /* Note: error is not fatal */
 762                 }
 763 #endif
 764
 765                 if (set_reuse_addr(sockfd)) {
 766                         close(sockfd);
 767                         continue;
 768                 }
 769
 770                 if (bind(sockfd, ai->ai_addr, ai->ai_addrlen) < 0) {
 771                         close(sockfd);
 772                         continue;       /* not fatal */
 773                 }
 774                 if (listen(sockfd, 5) < 0) {
 775                         close(sockfd);
 776                         continue;       /* not fatal */
 777                 }
 778
 779                 flags = fcntl(sockfd, F_GETFD, 0);
 780                 if (flags >= 0)
 781                         fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
 782
 783                 socklist = xrealloc(socklist, sizeof(int) * (socknum + 1));
 784                 socklist[socknum++] = sockfd;
 785
 786                 if (maxfd < sockfd)
 787                         maxfd = sockfd;
 788         }
 789
 790         freeaddrinfo(ai0);
 791
 792         *socklist_p = socklist;
 793         return socknum;
 794 }
 795
 796 #else /* NO_IPV6 */
 797
 798 static int socksetup(char *listen_addr, int listen_port, int **socklist_p)
 799 {
 800         struct sockaddr_in sin;
 801         int sockfd;
 802         long flags;
 803
 804         memset(&sin, 0, sizeof sin);
 805         sin.sin_family = AF_INET;
 806         sin.sin_port = htons(listen_port);
 807
 808         if (listen_addr) {
 809                 /* Well, host better be an IP address here. */
 810                 if (inet_pton(AF_INET, listen_addr, &sin.sin_addr.s_addr) <= 0)
 811                         return 0;
 812         } else {
 813                 sin.sin_addr.s_addr = htonl(INADDR_ANY);
 814         }
 815
 816         sockfd = socket(AF_INET, SOCK_STREAM, 0);
 817         if (sockfd < 0)
 818                 return 0;
 819
 820         if (set_reuse_addr(sockfd)) {
 821                 close(sockfd);
 822                 return 0;
 823         }
 824
 825         if ( bind(sockfd, (struct sockaddr *)&sin, sizeof sin) < 0 ) {
 826                 close(sockfd);
 827                 return 0;
 828         }
 829
 830         if (listen(sockfd, 5) < 0) {
 831                 close(sockfd);
 832                 return 0;
 833         }
 834
 835         flags = fcntl(sockfd, F_GETFD, 0);
 836         if (flags >= 0)
 837                 fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
 838
 839         *socklist_p = xmalloc(sizeof(int));
 840         **socklist_p = sockfd;
 841         return 1;
 842 }
 843
 844 #endif
 845
 846 static int service_loop(int socknum, int *socklist)
 847 {
 848         struct pollfd *pfd;
 849         int i;
 850
 851         pfd = xcalloc(socknum, sizeof(struct pollfd));
 852
 853         for (i = 0; i < socknum; i++) {
 854                 pfd[i].fd = socklist[i];
 855                 pfd[i].events = POLLIN;
 856         }
 857
 858         signal(SIGCHLD, child_handler);
 859
 860         for (;;) {
 861                 int i;
 862
 863                 check_dead_children();
 864
 865                 if (poll(pfd, socknum, -1) < 0) {
 866                         if (errno != EINTR) {
 867                                 logerror("Poll failed, resuming: %s",
 868                                       strerror(errno));
 869                                 sleep(1);
 870                         }
 871                         continue;
 872                 }
 873
 874                 for (i = 0; i < socknum; i++) {
 875                         if (pfd[i].revents & POLLIN) {
 876                                 struct sockaddr_storage ss;
 877                                 unsigned int sslen = sizeof(ss);
 878                                 int incoming = accept(pfd[i].fd, (struct sockaddr *)&ss, &sslen);
 879                                 if (incoming < 0) {
 880                                         switch (errno) {
 881                                         case EAGAIN:
 882                                         case EINTR:
 883                                         case ECONNABORTED:
 884                                                 continue;
 885                                         default:
 886                                                 die("accept returned %s", strerror(errno));
 887                                         }
 888                                 }
 889                                 handle(incoming, (struct sockaddr *)&ss, sslen);
 890                         }
 891                 }
 892         }
 893 }
 894
 895 /* if any standard file descriptor is missing open it to /dev/null */
 896 static void sanitize_stdfds(void)
 897 {
 898         int fd = open("/dev/null", O_RDWR, 0);
 899         while (fd != -1 && fd < 2)
 900                 fd = dup(fd);
 901         if (fd == -1)
 902                 die("open /dev/null or dup failed: %s", strerror(errno));
 903         if (fd > 2)
 904                 close(fd);
 905 }
 906
 907 static void daemonize(void)
 908 {
 909         switch (fork()) {
 910                 case 0:
 911                         break;
 912                 case -1:
 913                         die("fork failed: %s", strerror(errno));
 914                 default:
 915                         exit(0);
 916         }
 917         if (setsid() == -1)
 918                 die("setsid failed: %s", strerror(errno));
 919         close(0);
 920         close(1);
 921         close(2);
 922         sanitize_stdfds();
 923 }
 924
 925 static void store_pid(const char *path)
 926 {
 927         FILE *f = fopen(path, "w");
 928         if (!f)
 929                 die("cannot open pid file %s: %s", path, strerror(errno));
 930         if (fprintf(f, "%"PRIuMAX"\n", (uintmax_t) getpid()) < 0 || fclose(f) != 0)
 931                 die("failed to write pid file %s: %s", path, strerror(errno));
 932 }
 933
 934 static int serve(char *listen_addr, int listen_port, struct passwd *pass, gid_t gid)
 935 {
 936         int socknum, *socklist;
 937
 938         socknum = socksetup(listen_addr, listen_port, &socklist);
 939         if (socknum == 0)
 940                 die("unable to allocate any listen sockets on host %s port %u",
 941                     listen_addr, listen_port);
 942
 943         if (pass && gid &&
 944             (initgroups(pass->pw_name, gid) || setgid (gid) ||
 945              setuid(pass->pw_uid)))
 946                 die("cannot drop privileges");
 947
 948         return service_loop(socknum, socklist);
 949 }
 950
 951 int main(int argc, char **argv)
 952 {
 953         int listen_port = 0;
 954         char *listen_addr = NULL;
 955         int inetd_mode = 0;
 956         const char *pid_file = NULL, *user_name = NULL, *group_name = NULL;
 957         int detach = 0;
 958         struct passwd *pass = NULL;
 959         struct group *group;
 960         gid_t gid = 0;
 961         int i;
 962
 963         for (i = 1; i < argc; i++) {
 964                 char *arg = argv[i];
 965
 966                 if (!prefixcmp(arg, "--listen=")) {
 967                     char *p = arg + 9;
 968                     char *ph = listen_addr = xmalloc(strlen(arg + 9) + 1);
 969                     while (*p)
 970                         *ph++ = tolower(*p++);
 971                     *ph = 0;
 972                     continue;
 973                 }
 974                 if (!prefixcmp(arg, "--port=")) {
 975                         char *end;
 976                         unsigned long n;
 977                         n = strtoul(arg+7, &end, 0);
 978                         if (arg[7] && !*end) {
 979                                 listen_port = n;
 980                                 continue;
 981                         }
 982                 }
 983                 if (!strcmp(arg, "--inetd")) {
 984                         inetd_mode = 1;
 985                         log_syslog = 1;
 986                         continue;
 987                 }
 988                 if (!strcmp(arg, "--verbose")) {
 989                         verbose = 1;
 990                         continue;
 991                 }
 992                 if (!strcmp(arg, "--syslog")) {
 993                         log_syslog = 1;
 994                         continue;
 995                 }
 996                 if (!strcmp(arg, "--export-all")) {
 997                         export_all_trees = 1;
 998                         continue;
 999                 }
1000                 if (!prefixcmp(arg, "--timeout=")) {
1001                         timeout = atoi(arg+10);
1002                         continue;
1003                 }
1004                 if (!prefixcmp(arg, "--init-timeout=")) {
1005                         init_timeout = atoi(arg+15);
1006                         continue;
1007                 }
1008                 if (!prefixcmp(arg, "--max-connections=")) {
1009                         max_connections = atoi(arg+18);
1010                         if (max_connections < 0)
1011                                 max_connections = 0;            /* unlimited */
1012                         continue;
1013                 }
1014                 if (!strcmp(arg, "--strict-paths")) {
1015                         strict_paths = 1;
1016                         continue;
1017                 }
1018                 if (!prefixcmp(arg, "--base-path=")) {
1019                         base_path = arg+12;
1020                         continue;
1021                 }
1022                 if (!strcmp(arg, "--base-path-relaxed")) {
1023                         base_path_relaxed = 1;
1024                         continue;
1025                 }
1026                 if (!prefixcmp(arg, "--interpolated-path=")) {
1027                         interpolated_path = arg+20;
1028                         continue;
1029                 }
1030                 if (!strcmp(arg, "--reuseaddr")) {
1031                         reuseaddr = 1;
1032                         continue;
1033                 }
1034                 if (!strcmp(arg, "--user-path")) {
1035                         user_path = "";
1036                         continue;
1037                 }
1038                 if (!prefixcmp(arg, "--user-path=")) {
1039                         user_path = arg + 12;
1040                         continue;
1041                 }
1042                 if (!prefixcmp(arg, "--pid-file=")) {
1043                         pid_file = arg + 11;
1044                         continue;
1045                 }
1046                 if (!strcmp(arg, "--detach")) {
1047                         detach = 1;
1048                         log_syslog = 1;
1049                         continue;
1050                 }
1051                 if (!prefixcmp(arg, "--user=")) {
1052                         user_name = arg + 7;
1053                         continue;
1054                 }
1055                 if (!prefixcmp(arg, "--group=")) {
1056                         group_name = arg + 8;
1057                         continue;
1058                 }
1059                 if (!prefixcmp(arg, "--enable=")) {
1060                         enable_service(arg + 9, 1);
1061                         continue;
1062                 }
1063                 if (!prefixcmp(arg, "--disable=")) {
1064                         enable_service(arg + 10, 0);
1065                         continue;
1066                 }
1067                 if (!prefixcmp(arg, "--allow-override=")) {
1068                         make_service_overridable(arg + 17, 1);
1069                         continue;
1070                 }
1071                 if (!prefixcmp(arg, "--forbid-override=")) {
1072                         make_service_overridable(arg + 18, 0);
1073                         continue;
1074                 }
1075                 if (!strcmp(arg, "--")) {
1076                         ok_paths = &argv[i+1];
1077                         break;
1078                 } else if (arg[0] != '-') {
1079                         ok_paths = &argv[i];
1080                         break;
1081                 }
1082
1083                 usage(daemon_usage);
1084         }
1085
1086         if (log_syslog) {
1087                 openlog("git-daemon", LOG_PID, LOG_DAEMON);
1088                 set_die_routine(daemon_die);
1089         } else
1090                 /* avoid splitting a message in the middle */
1091                 setvbuf(stderr, NULL, _IOLBF, 0);
1092
1093         if (inetd_mode && (group_name || user_name))
1094                 die("--user and --group are incompatible with --inetd");
1095
1096         if (inetd_mode && (listen_port || listen_addr))
1097                 die("--listen= and --port= are incompatible with --inetd");
1098         else if (listen_port == 0)
1099                 listen_port = DEFAULT_GIT_PORT;
1100
1101         if (group_name && !user_name)
1102                 die("--group supplied without --user");
1103
1104         if (user_name) {
1105                 pass = getpwnam(user_name);
1106                 if (!pass)
1107                         die("user not found - %s", user_name);
1108
1109                 if (!group_name)
1110                         gid = pass->pw_gid;
1111                 else {
1112                         group = getgrnam(group_name);
1113                         if (!group)
1114                                 die("group not found - %s", group_name);
1115
1116                         gid = group->gr_gid;
1117                 }
1118         }
1119
1120         if (strict_paths && (!ok_paths || !*ok_paths))
1121                 die("option --strict-paths requires a whitelist");
1122
1123         if (base_path && !is_directory(base_path))
1124                 die("base-path '%s' does not exist or is not a directory",
1125                     base_path);
1126
1127         if (inetd_mode) {
1128                 struct sockaddr_storage ss;
1129                 struct sockaddr *peer = (struct sockaddr *)&ss;
1130                 socklen_t slen = sizeof(ss);
1131
1132                 freopen("/dev/null", "w", stderr);
1133
1134                 if (getpeername(0, peer, &slen))
1135                         peer = NULL;
1136
1137                 return execute(peer);
1138         }
1139
1140         if (detach) {
1141                 daemonize();
1142                 loginfo("Ready to rumble");
1143         }
1144         else
1145                 sanitize_stdfds();
1146
1147         if (pid_file)
1148                 store_pid(pid_file);
1149
1150         return serve(listen_addr, listen_port, pass, gid);
1151 }