daemon.c

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