daemon.c

   1 #include "cache.h"
   2 #include "pkt-line.h"
   3 #include "exec_cmd.h"
   4 #include "run-command.h"
   5 #include "strbuf.h"
   6
   7 #include <syslog.h>
   8
   9 #ifndef HOST_NAME_MAX
  10 #define HOST_NAME_MAX 256
  11 #endif
  12
  13 #ifndef NI_MAXSERV
  14 #define NI_MAXSERV 32
  15 #endif
  16
  17 static int log_syslog;
  18 static int verbose;
  19 static int reuseaddr;
  20
  21 static const char daemon_usage[] =
  22 "git daemon [--verbose] [--syslog] [--export-all]\n"
  23 "           [--timeout=n] [--init-timeout=n] [--max-connections=n]\n"
  24 "           [--strict-paths] [--base-path=path] [--base-path-relaxed]\n"
  25 "           [--user-path | --user-path=path]\n"
  26 "           [--interpolated-path=path]\n"
  27 "           [--reuseaddr] [--detach] [--pid-file=file]\n"
  28 "           [--[enable|disable|allow-override|forbid-override]=service]\n"
  29 "           [--inetd | [--listen=host_or_ipaddr] [--port=n]\n"
  30 "                      [--user=user [--group=group]]\n"
  31 "           [directory...]";
  32
  33 /* List of acceptable pathname prefixes */
  34 static char **ok_paths;
  35 static int strict_paths;
  36
  37 /* If this is set, git-daemon-export-ok is not required */
  38 static int export_all_trees;
  39
  40 /* Take all paths relative to this one if non-NULL */
  41 static char *base_path;
  42 static char *interpolated_path;
  43 static int base_path_relaxed;
  44
  45 /* Flag indicating client sent extra args. */
  46 static int saw_extended_args;
  47
  48 /* If defined, ~user notation is allowed and the string is inserted
  49  * after ~user/.  E.g. a request to git://host/~alice/frotz would
  50  * go to /home/alice/pub_git/frotz with --user-path=pub_git.
  51  */
  52 static const char *user_path;
  53
  54 /* Timeout, and initial timeout */
  55 static unsigned int timeout;
  56 static unsigned int init_timeout;
  57
  58 static char *hostname;
  59 static char *canon_hostname;
  60 static char *ip_address;
  61 static char *tcp_port;
  62
  63 static void logreport(int priority, const char *err, va_list params)
  64 {
  65         if (log_syslog) {
  66                 char buf[1024];
  67                 vsnprintf(buf, sizeof(buf), err, params);
  68                 syslog(priority, "%s", buf);
  69         } else {
  70                 /*
  71                  * Since stderr is set to linebuffered mode, the
  72                  * logging of different processes will not overlap
  73                  */
  74                 fprintf(stderr, "[%"PRIuMAX"] ", (uintmax_t)getpid());
  75                 vfprintf(stderr, err, params);
  76                 fputc('\n', stderr);
  77         }
  78 }
  79
  80 static void logerror(const char *err, ...)
  81 {
  82         va_list params;
  83         va_start(params, err);
  84         logreport(LOG_ERR, err, params);
  85         va_end(params);
  86 }
  87
  88 static void loginfo(const char *err, ...)
  89 {
  90         va_list params;
  91         if (!verbose)
  92                 return;
  93         va_start(params, err);
  94         logreport(LOG_INFO, err, params);
  95         va_end(params);
  96 }
  97
  98 static void NORETURN daemon_die(const char *err, va_list params)
  99 {
 100         logreport(LOG_ERR, err, params);
 101         exit(1);
 102 }
 103
 104 static int avoid_alias(char *p)
 105 {
 106         int sl, ndot;
 107
 108         /*
 109          * This resurrects the belts and suspenders paranoia check by HPA
 110          * done in <435560F7.4080006@zytor.com> thread, now enter_repo()
 111          * does not do getcwd() based path canonicalizations.
 112          *
 113          * sl becomes true immediately after seeing '/' and continues to
 114          * be true as long as dots continue after that without intervening
 115          * non-dot character.
 116          */
 117         if (!p || (*p != '/' && *p != '~'))
 118                 return -1;
 119         sl = 1; ndot = 0;
 120         p++;
 121
 122         while (1) {
 123                 char ch = *p++;
 124                 if (sl) {
 125                         if (ch == '.')
 126                                 ndot++;
 127                         else if (ch == '/') {
 128                                 if (ndot < 3)
 129                                         /* reject //, /./ and /../ */
 130                                         return -1;
 131                                 ndot = 0;
 132                         }
 133                         else if (ch == 0) {
 134                                 if (0 < ndot && ndot < 3)
 135                                         /* reject /.$ and /..$ */
 136                                         return -1;
 137                                 return 0;
 138                         }
 139                         else
 140                                 sl = ndot = 0;
 141                 }
 142                 else if (ch == 0)
 143                         return 0;
 144                 else if (ch == '/') {
 145                         sl = 1;
 146                         ndot = 0;
 147                 }
 148         }
 149 }
 150
 151 static char *path_ok(char *directory)
 152 {
 153         static char rpath[PATH_MAX];
 154         static char interp_path[PATH_MAX];
 155         char *path;
 156         char *dir;
 157
 158         dir = directory;
 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 (interpolated_path && saw_extended_args) {
 188                 struct strbuf expanded_path = STRBUF_INIT;
 189                 struct strbuf_expand_dict_entry dict[] = {
 190                         { "H", hostname },
 191                         { "CH", canon_hostname },
 192                         { "IP", ip_address },
 193                         { "P", tcp_port },
 194                         { "D", directory },
 195                         { "%", "%" },
 196                         { NULL }
 197                 };
 198
 199                 if (*dir != '/') {
 200                         /* Allow only absolute */
 201                         logerror("'%s': Non-absolute path denied (interpolated-path active)", dir);
 202                         return NULL;
 203                 }
 204
 205                 strbuf_expand(&expanded_path, interpolated_path,
 206                                 strbuf_expand_dict_cb, &dict);
 207                 strlcpy(interp_path, expanded_path.buf, PATH_MAX);
 208                 strbuf_release(&expanded_path);
 209                 loginfo("Interpolated dir '%s'", interp_path);
 210
 211                 dir = interp_path;
 212         }
 213         else if (base_path) {
 214                 if (*dir != '/') {
 215                         /* Allow only absolute */
 216                         logerror("'%s': Non-absolute path denied (base-path active)", dir);
 217                         return NULL;
 218                 }
 219                 snprintf(rpath, PATH_MAX, "%s%s", base_path, dir);
 220                 dir = rpath;
 221         }
 222
 223         path = enter_repo(dir, strict_paths);
 224         if (!path && base_path && base_path_relaxed) {
 225                 /*
 226                  * if we fail and base_path_relaxed is enabled, try without
 227                  * prefixing the base path
 228                  */
 229                 dir = directory;
 230                 path = enter_repo(dir, strict_paths);
 231         }
 232
 233         if (!path) {
 234                 logerror("'%s' does not appear to be a git repository", dir);
 235                 return NULL;
 236         }
 237
 238         if ( ok_paths && *ok_paths ) {
 239                 char **pp;
 240                 int pathlen = strlen(path);
 241
 242                 /* The validation is done on the paths after enter_repo
 243                  * appends optional {.git,.git/.git} and friends, but
 244                  * it does not use getcwd().  So if your /pub is
 245                  * a symlink to /mnt/pub, you can whitelist /pub and
 246                  * do not have to say /mnt/pub.
 247                  * Do not say /pub/.
 248                  */
 249                 for ( pp = ok_paths ; *pp ; pp++ ) {
 250                         int len = strlen(*pp);
 251                         if (len <= pathlen &&
 252                             !memcmp(*pp, path, len) &&
 253                             (path[len] == '\0' ||
 254                              (!strict_paths && path[len] == '/')))
 255                                 return path;
 256                 }
 257         }
 258         else {
 259                 /* be backwards compatible */
 260                 if (!strict_paths)
 261                         return path;
 262         }
 263
 264         logerror("'%s': not in whitelist", path);
 265         return NULL;            /* Fallthrough. Deny by default */
 266 }
 267
 268 typedef int (*daemon_service_fn)(void);
 269 struct daemon_service {
 270         const char *name;
 271         const char *config_name;
 272         daemon_service_fn fn;
 273         int enabled;
 274         int overridable;
 275 };
 276
 277 static struct daemon_service *service_looking_at;
 278 static int service_enabled;
 279
 280 static int git_daemon_config(const char *var, const char *value, void *cb)
 281 {
 282         if (!prefixcmp(var, "daemon.") &&
 283             !strcmp(var + 7, service_looking_at->config_name)) {
 284                 service_enabled = git_config_bool(var, value);
 285                 return 0;
 286         }
 287
 288         /* we are not interested in parsing any other configuration here */
 289         return 0;
 290 }
 291
 292 static int run_service(char *dir, struct daemon_service *service)
 293 {
 294         const char *path;
 295         int enabled = service->enabled;
 296
 297         loginfo("Request %s for '%s'", service->name, dir);
 298
 299         if (!enabled && !service->overridable) {
 300                 logerror("'%s': service not enabled.", service->name);
 301                 errno = EACCES;
 302                 return -1;
 303         }
 304
 305         if (!(path = path_ok(dir)))
 306                 return -1;
 307
 308         /*
 309          * Security on the cheap.
 310          *
 311          * We want a readable HEAD, usable "objects" directory, and
 312          * a "git-daemon-export-ok" flag that says that the other side
 313          * is ok with us doing this.
 314          *
 315          * path_ok() uses enter_repo() and does whitelist checking.
 316          * We only need to make sure the repository is exported.
 317          */
 318
 319         if (!export_all_trees && access("git-daemon-export-ok", F_OK)) {
 320                 logerror("'%s': repository not exported.", path);
 321                 errno = EACCES;
 322                 return -1;
 323         }
 324
 325         if (service->overridable) {
 326                 service_looking_at = service;
 327                 service_enabled = -1;
 328                 git_config(git_daemon_config, NULL);
 329                 if (0 <= service_enabled)
 330                         enabled = service_enabled;
 331         }
 332         if (!enabled) {
 333                 logerror("'%s': service not enabled for '%s'",
 334                          service->name, path);
 335                 errno = EACCES;
 336                 return -1;
 337         }
 338
 339         /*
 340          * We'll ignore SIGTERM from now on, we have a
 341          * good client.
 342          */
 343         signal(SIGTERM, SIG_IGN);
 344
 345         return service->fn();
 346 }
 347
 348 static void copy_to_log(int fd)
 349 {
 350         struct strbuf line = STRBUF_INIT;
 351         FILE *fp;
 352
 353         fp = fdopen(fd, "r");
 354         if (fp == NULL) {
 355                 logerror("fdopen of error channel failed");
 356                 close(fd);
 357                 return;
 358         }
 359
 360         while (strbuf_getline(&line, fp, '\n') != EOF) {
 361                 logerror("%s", line.buf);
 362                 strbuf_setlen(&line, 0);
 363         }
 364
 365         strbuf_release(&line);
 366         fclose(fp);
 367 }
 368
 369 static int run_service_command(const char **argv)
 370 {
 371         struct child_process cld;
 372
 373         memset(&cld, 0, sizeof(cld));
 374         cld.argv = argv;
 375         cld.git_cmd = 1;
 376         cld.err = -1;
 377         if (start_command(&cld))
 378                 return -1;
 379
 380         close(0);
 381         close(1);
 382
 383         copy_to_log(cld.err);
 384
 385         return finish_command(&cld);
 386 }
 387
 388 static int upload_pack(void)
 389 {
 390         /* Timeout as string */
 391         char timeout_buf[64];
 392         const char *argv[] = { "upload-pack", "--strict", timeout_buf, ".", NULL };
 393
 394         snprintf(timeout_buf, sizeof timeout_buf, "--timeout=%u", timeout);
 395         return run_service_command(argv);
 396 }
 397
 398 static int upload_archive(void)
 399 {
 400         static const char *argv[] = { "upload-archive", ".", NULL };
 401         return run_service_command(argv);
 402 }
 403
 404 static int receive_pack(void)
 405 {
 406         static const char *argv[] = { "receive-pack", ".", NULL };
 407         return run_service_command(argv);
 408 }
 409
 410 static struct daemon_service daemon_service[] = {
 411         { "upload-archive", "uploadarch", upload_archive, 0, 1 },
 412         { "upload-pack", "uploadpack", upload_pack, 1, 1 },
 413         { "receive-pack", "receivepack", receive_pack, 0, 1 },
 414 };
 415
 416 static void enable_service(const char *name, int ena)
 417 {
 418         int i;
 419         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 420                 if (!strcmp(daemon_service[i].name, name)) {
 421                         daemon_service[i].enabled = ena;
 422                         return;
 423                 }
 424         }
 425         die("No such service %s", name);
 426 }
 427
 428 static void make_service_overridable(const char *name, int ena)
 429 {
 430         int i;
 431         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 432                 if (!strcmp(daemon_service[i].name, name)) {
 433                         daemon_service[i].overridable = ena;
 434                         return;
 435                 }
 436         }
 437         die("No such service %s", name);
 438 }
 439
 440 static char *xstrdup_tolower(const char *str)
 441 {
 442         char *p, *dup = xstrdup(str);
 443         for (p = dup; *p; p++)
 444                 *p = tolower(*p);
 445         return dup;
 446 }
 447
 448 static void parse_host_and_port(char *hostport, char **host,
 449         char **port)
 450 {
 451         if (*hostport == '[') {
 452                 char *end;
 453
 454                 end = strchr(hostport, ']');
 455                 if (!end)
 456                         die("Invalid reqeuest ('[' without ']')");
 457                 *end = '\0';
 458                 *host = hostport + 1;
 459                 if (!end[1])
 460                         *port = NULL;
 461                 else if (end[1] == ':')
 462                         *port = end + 2;
 463                 else
 464                         die("Garbage after end of host part");
 465         } else {
 466                 *host = hostport;
 467                 *port = strrchr(hostport, ':');
 468                 if (*port) {
 469                         *port = '\0';
 470                         ++*port;
 471                 }
 472         }
 473 }
 474
 475 /*
 476  * Read the host as supplied by the client connection.
 477  */
 478 static void parse_host_arg(char *extra_args, int buflen)
 479 {
 480         char *val;
 481         int vallen;
 482         char *end = extra_args + buflen;
 483
 484         if (extra_args < end && *extra_args) {
 485                 saw_extended_args = 1;
 486                 if (strncasecmp("host=", extra_args, 5) == 0) {
 487                         val = extra_args + 5;
 488                         vallen = strlen(val) + 1;
 489                         if (*val) {
 490                                 /* Split <host>:<port> at colon. */
 491                                 char *host;
 492                                 char *port;
 493                                 parse_host_and_port(val, &host, &port);
 494                                 if (port) {
 495                                         free(tcp_port);
 496                                         tcp_port = xstrdup(port);
 497                                 }
 498                                 free(hostname);
 499                                 hostname = xstrdup_tolower(host);
 500                         }
 501
 502                         /* On to the next one */
 503                         extra_args = val + vallen;
 504                 }
 505                 if (extra_args < end && *extra_args)
 506                         die("Invalid request");
 507         }
 508
 509         /*
 510          * Locate canonical hostname and its IP address.
 511          */
 512         if (hostname) {
 513 #ifndef NO_IPV6
 514                 struct addrinfo hints;
 515                 struct addrinfo *ai;
 516                 int gai;
 517                 static char addrbuf[HOST_NAME_MAX + 1];
 518
 519                 memset(&hints, 0, sizeof(hints));
 520                 hints.ai_flags = AI_CANONNAME;
 521
 522                 gai = getaddrinfo(hostname, NULL, &hints, &ai);
 523                 if (!gai) {
 524                         struct sockaddr_in *sin_addr = (void *)ai->ai_addr;
 525
 526                         inet_ntop(AF_INET, &sin_addr->sin_addr,
 527                                   addrbuf, sizeof(addrbuf));
 528                         free(ip_address);
 529                         ip_address = xstrdup(addrbuf);
 530
 531                         free(canon_hostname);
 532                         canon_hostname = xstrdup(ai->ai_canonname ?
 533                                                  ai->ai_canonname : ip_address);
 534
 535                         freeaddrinfo(ai);
 536                 }
 537 #else
 538                 struct hostent *hent;
 539                 struct sockaddr_in sa;
 540                 char **ap;
 541                 static char addrbuf[HOST_NAME_MAX + 1];
 542
 543                 hent = gethostbyname(hostname);
 544
 545                 ap = hent->h_addr_list;
 546                 memset(&sa, 0, sizeof sa);
 547                 sa.sin_family = hent->h_addrtype;
 548                 sa.sin_port = htons(0);
 549                 memcpy(&sa.sin_addr, *ap, hent->h_length);
 550
 551                 inet_ntop(hent->h_addrtype, &sa.sin_addr,
 552                           addrbuf, sizeof(addrbuf));
 553
 554                 free(canon_hostname);
 555                 canon_hostname = xstrdup(hent->h_name);
 556                 free(ip_address);
 557                 ip_address = xstrdup(addrbuf);
 558 #endif
 559         }
 560 }
 561
 562
 563 static int execute(struct sockaddr *addr)
 564 {
 565         static char line[1000];
 566         int pktlen, len, i;
 567
 568         if (addr) {
 569                 char addrbuf[256] = "";
 570                 int port = -1;
 571
 572                 if (addr->sa_family == AF_INET) {
 573                         struct sockaddr_in *sin_addr = (void *) addr;
 574                         inet_ntop(addr->sa_family, &sin_addr->sin_addr, addrbuf, sizeof(addrbuf));
 575                         port = ntohs(sin_addr->sin_port);
 576 #ifndef NO_IPV6
 577                 } else if (addr && addr->sa_family == AF_INET6) {
 578                         struct sockaddr_in6 *sin6_addr = (void *) addr;
 579
 580                         char *buf = addrbuf;
 581                         *buf++ = '['; *buf = '\0'; /* stpcpy() is cool */
 582                         inet_ntop(AF_INET6, &sin6_addr->sin6_addr, buf, sizeof(addrbuf) - 1);
 583                         strcat(buf, "]");
 584
 585                         port = ntohs(sin6_addr->sin6_port);
 586 #endif
 587                 }
 588                 loginfo("Connection from %s:%d", addrbuf, port);
 589                 setenv("REMOTE_ADDR", addrbuf, 1);
 590         }
 591         else {
 592                 unsetenv("REMOTE_ADDR");
 593         }
 594
 595         alarm(init_timeout ? init_timeout : timeout);
 596         pktlen = packet_read_line(0, line, sizeof(line));
 597         alarm(0);
 598
 599         len = strlen(line);
 600         if (pktlen != len)
 601                 loginfo("Extended attributes (%d bytes) exist <%.*s>",
 602                         (int) pktlen - len,
 603                         (int) pktlen - len, line + len + 1);
 604         if (len && line[len-1] == '\n') {
 605                 line[--len] = 0;
 606                 pktlen--;
 607         }
 608
 609         free(hostname);
 610         free(canon_hostname);
 611         free(ip_address);
 612         free(tcp_port);
 613         hostname = canon_hostname = ip_address = tcp_port = NULL;
 614
 615         if (len != pktlen)
 616                 parse_host_arg(line + len + 1, pktlen - len - 1);
 617
 618         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 619                 struct daemon_service *s = &(daemon_service[i]);
 620                 int namelen = strlen(s->name);
 621                 if (!prefixcmp(line, "git-") &&
 622                     !strncmp(s->name, line + 4, namelen) &&
 623                     line[namelen + 4] == ' ') {
 624                         /*
 625                          * Note: The directory here is probably context sensitive,
 626                          * and might depend on the actual service being performed.
 627                          */
 628                         return run_service(line + namelen + 5, s);
 629                 }
 630         }
 631
 632         logerror("Protocol error: '%s'", line);
 633         return -1;
 634 }
 635
 636 static int max_connections = 32;
 637
 638 static unsigned int live_children;
 639
 640 static struct child {
 641         struct child *next;
 642         pid_t pid;
 643         struct sockaddr_storage address;
 644 } *firstborn;
 645
 646 static void add_child(pid_t pid, struct sockaddr *addr, int addrlen)
 647 {
 648         struct child *newborn, **cradle;
 649
 650         /*
 651          * This must be xcalloc() -- we'll compare the whole sockaddr_storage
 652          * but individual address may be shorter.
 653          */
 654         newborn = xcalloc(1, sizeof(*newborn));
 655         live_children++;
 656         newborn->pid = pid;
 657         memcpy(&newborn->address, addr, addrlen);
 658         for (cradle = &firstborn; *cradle; cradle = &(*cradle)->next)
 659                 if (!memcmp(&(*cradle)->address, &newborn->address,
 660                             sizeof(newborn->address)))
 661                         break;
 662         newborn->next = *cradle;
 663         *cradle = newborn;
 664 }
 665
 666 static void remove_child(pid_t pid)
 667 {
 668         struct child **cradle, *blanket;
 669
 670         for (cradle = &firstborn; (blanket = *cradle); cradle = &blanket->next)
 671                 if (blanket->pid == pid) {
 672                         *cradle = blanket->next;
 673                         live_children--;
 674                         free(blanket);
 675                         break;
 676                 }
 677 }
 678
 679 /*
 680  * This gets called if the number of connections grows
 681  * past "max_connections".
 682  *
 683  * We kill the newest connection from a duplicate IP.
 684  */
 685 static void kill_some_child(void)
 686 {
 687         const struct child *blanket, *next;
 688
 689         if (!(blanket = firstborn))
 690                 return;
 691
 692         for (; (next = blanket->next); blanket = next)
 693                 if (!memcmp(&blanket->address, &next->address,
 694                             sizeof(next->address))) {
 695                         kill(blanket->pid, SIGTERM);
 696                         break;
 697                 }
 698 }
 699
 700 static void check_dead_children(void)
 701 {
 702         int status;
 703         pid_t pid;
 704
 705         while ((pid = waitpid(-1, &status, WNOHANG)) > 0) {
 706                 const char *dead = "";
 707                 remove_child(pid);
 708                 if (!WIFEXITED(status) || (WEXITSTATUS(status) > 0))
 709                         dead = " (with error)";
 710                 loginfo("[%"PRIuMAX"] Disconnected%s", (uintmax_t)pid, dead);
 711         }
 712 }
 713
 714 static void handle(int incoming, struct sockaddr *addr, int addrlen)
 715 {
 716         pid_t pid;
 717
 718         if (max_connections && live_children >= max_connections) {
 719                 kill_some_child();
 720                 sleep(1);  /* give it some time to die */
 721                 check_dead_children();
 722                 if (live_children >= max_connections) {
 723                         close(incoming);
 724                         logerror("Too many children, dropping connection");
 725                         return;
 726                 }
 727         }
 728
 729         if ((pid = fork())) {
 730                 close(incoming);
 731                 if (pid < 0) {
 732                         logerror("Couldn't fork %s", strerror(errno));
 733                         return;
 734                 }
 735
 736                 add_child(pid, addr, addrlen);
 737                 return;
 738         }
 739
 740         dup2(incoming, 0);
 741         dup2(incoming, 1);
 742         close(incoming);
 743
 744         exit(execute(addr));
 745 }
 746
 747 static void child_handler(int signo)
 748 {
 749         /*
 750          * Otherwise empty handler because systemcalls will get interrupted
 751          * upon signal receipt
 752          * SysV needs the handler to be rearmed
 753          */
 754         signal(SIGCHLD, child_handler);
 755 }
 756
 757 static int set_reuse_addr(int sockfd)
 758 {
 759         int on = 1;
 760
 761         if (!reuseaddr)
 762                 return 0;
 763         return setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
 764                           &on, sizeof(on));
 765 }
 766
 767 #ifndef NO_IPV6
 768
 769 static int socksetup(char *listen_addr, int listen_port, int **socklist_p)
 770 {
 771         int socknum = 0, *socklist = NULL;
 772         int maxfd = -1;
 773         char pbuf[NI_MAXSERV];
 774         struct addrinfo hints, *ai0, *ai;
 775         int gai;
 776         long flags;
 777
 778         sprintf(pbuf, "%d", listen_port);
 779         memset(&hints, 0, sizeof(hints));
 780         hints.ai_family = AF_UNSPEC;
 781         hints.ai_socktype = SOCK_STREAM;
 782         hints.ai_protocol = IPPROTO_TCP;
 783         hints.ai_flags = AI_PASSIVE;
 784
 785         gai = getaddrinfo(listen_addr, pbuf, &hints, &ai0);
 786         if (gai)
 787                 die("getaddrinfo() failed: %s", gai_strerror(gai));
 788
 789         for (ai = ai0; ai; ai = ai->ai_next) {
 790                 int sockfd;
 791
 792                 sockfd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
 793                 if (sockfd < 0)
 794                         continue;
 795                 if (sockfd >= FD_SETSIZE) {
 796                         logerror("Socket descriptor too large");
 797                         close(sockfd);
 798                         continue;
 799                 }
 800
 801 #ifdef IPV6_V6ONLY
 802                 if (ai->ai_family == AF_INET6) {
 803                         int on = 1;
 804                         setsockopt(sockfd, IPPROTO_IPV6, IPV6_V6ONLY,
 805                                    &on, sizeof(on));
 806                         /* Note: error is not fatal */
 807                 }
 808 #endif
 809
 810                 if (set_reuse_addr(sockfd)) {
 811                         close(sockfd);
 812                         continue;
 813                 }
 814
 815                 if (bind(sockfd, ai->ai_addr, ai->ai_addrlen) < 0) {
 816                         close(sockfd);
 817                         continue;       /* not fatal */
 818                 }
 819                 if (listen(sockfd, 5) < 0) {
 820                         close(sockfd);
 821                         continue;       /* not fatal */
 822                 }
 823
 824                 flags = fcntl(sockfd, F_GETFD, 0);
 825                 if (flags >= 0)
 826                         fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
 827
 828                 socklist = xrealloc(socklist, sizeof(int) * (socknum + 1));
 829                 socklist[socknum++] = sockfd;
 830
 831                 if (maxfd < sockfd)
 832                         maxfd = sockfd;
 833         }
 834
 835         freeaddrinfo(ai0);
 836
 837         *socklist_p = socklist;
 838         return socknum;
 839 }
 840
 841 #else /* NO_IPV6 */
 842
 843 static int socksetup(char *listen_addr, int listen_port, int **socklist_p)
 844 {
 845         struct sockaddr_in sin;
 846         int sockfd;
 847         long flags;
 848
 849         memset(&sin, 0, sizeof sin);
 850         sin.sin_family = AF_INET;
 851         sin.sin_port = htons(listen_port);
 852
 853         if (listen_addr) {
 854                 /* Well, host better be an IP address here. */
 855                 if (inet_pton(AF_INET, listen_addr, &sin.sin_addr.s_addr) <= 0)
 856                         return 0;
 857         } else {
 858                 sin.sin_addr.s_addr = htonl(INADDR_ANY);
 859         }
 860
 861         sockfd = socket(AF_INET, SOCK_STREAM, 0);
 862         if (sockfd < 0)
 863                 return 0;
 864
 865         if (set_reuse_addr(sockfd)) {
 866                 close(sockfd);
 867                 return 0;
 868         }
 869
 870         if ( bind(sockfd, (struct sockaddr *)&sin, sizeof sin) < 0 ) {
 871                 close(sockfd);
 872                 return 0;
 873         }
 874
 875         if (listen(sockfd, 5) < 0) {
 876                 close(sockfd);
 877                 return 0;
 878         }
 879
 880         flags = fcntl(sockfd, F_GETFD, 0);
 881         if (flags >= 0)
 882                 fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
 883
 884         *socklist_p = xmalloc(sizeof(int));
 885         **socklist_p = sockfd;
 886         return 1;
 887 }
 888
 889 #endif
 890
 891 static int service_loop(int socknum, int *socklist)
 892 {
 893         struct pollfd *pfd;
 894         int i;
 895
 896         pfd = xcalloc(socknum, sizeof(struct pollfd));
 897
 898         for (i = 0; i < socknum; i++) {
 899                 pfd[i].fd = socklist[i];
 900                 pfd[i].events = POLLIN;
 901         }
 902
 903         signal(SIGCHLD, child_handler);
 904
 905         for (;;) {
 906                 int i;
 907
 908                 check_dead_children();
 909
 910                 if (poll(pfd, socknum, -1) < 0) {
 911                         if (errno != EINTR) {
 912                                 logerror("Poll failed, resuming: %s",
 913                                       strerror(errno));
 914                                 sleep(1);
 915                         }
 916                         continue;
 917                 }
 918
 919                 for (i = 0; i < socknum; i++) {
 920                         if (pfd[i].revents & POLLIN) {
 921                                 struct sockaddr_storage ss;
 922                                 unsigned int sslen = sizeof(ss);
 923                                 int incoming = accept(pfd[i].fd, (struct sockaddr *)&ss, &sslen);
 924                                 if (incoming < 0) {
 925                                         switch (errno) {
 926                                         case EAGAIN:
 927                                         case EINTR:
 928                                         case ECONNABORTED:
 929                                                 continue;
 930                                         default:
 931                                                 die_errno("accept returned");
 932                                         }
 933                                 }
 934                                 handle(incoming, (struct sockaddr *)&ss, sslen);
 935                         }
 936                 }
 937         }
 938 }
 939
 940 /* if any standard file descriptor is missing open it to /dev/null */
 941 static void sanitize_stdfds(void)
 942 {
 943         int fd = open("/dev/null", O_RDWR, 0);
 944         while (fd != -1 && fd < 2)
 945                 fd = dup(fd);
 946         if (fd == -1)
 947                 die_errno("open /dev/null or dup failed");
 948         if (fd > 2)
 949                 close(fd);
 950 }
 951
 952 static void daemonize(void)
 953 {
 954         switch (fork()) {
 955                 case 0:
 956                         break;
 957                 case -1:
 958                         die_errno("fork failed");
 959                 default:
 960                         exit(0);
 961         }
 962         if (setsid() == -1)
 963                 die_errno("setsid failed");
 964         close(0);
 965         close(1);
 966         close(2);
 967         sanitize_stdfds();
 968 }
 969
 970 static void store_pid(const char *path)
 971 {
 972         FILE *f = fopen(path, "w");
 973         if (!f)
 974                 die_errno("cannot open pid file '%s'", path);
 975         if (fprintf(f, "%"PRIuMAX"\n", (uintmax_t) getpid()) < 0 || fclose(f) != 0)
 976                 die_errno("failed to write pid file '%s'", path);
 977 }
 978
 979 static int serve(char *listen_addr, int listen_port, struct passwd *pass, gid_t gid)
 980 {
 981         int socknum, *socklist;
 982
 983         socknum = socksetup(listen_addr, listen_port, &socklist);
 984         if (socknum == 0)
 985                 die("unable to allocate any listen sockets on host %s port %u",
 986                     listen_addr, listen_port);
 987
 988         if (pass && gid &&
 989             (initgroups(pass->pw_name, gid) || setgid (gid) ||
 990              setuid(pass->pw_uid)))
 991                 die("cannot drop privileges");
 992
 993         return service_loop(socknum, socklist);
 994 }
 995
 996 int main(int argc, char **argv)
 997 {
 998         int listen_port = 0;
 999         char *listen_addr = NULL;
1000         int inetd_mode = 0;
1001         const char *pid_file = NULL, *user_name = NULL, *group_name = NULL;
1002         int detach = 0;
1003         struct passwd *pass = NULL;
1004         struct group *group;
1005         gid_t gid = 0;
1006         int i;
1007
1008         git_extract_argv0_path(argv[0]);
1009
1010         for (i = 1; i < argc; i++) {
1011                 char *arg = argv[i];
1012
1013                 if (!prefixcmp(arg, "--listen=")) {
1014                         listen_addr = xstrdup_tolower(arg + 9);
1015                         continue;
1016                 }
1017                 if (!prefixcmp(arg, "--port=")) {
1018                         char *end;
1019                         unsigned long n;
1020                         n = strtoul(arg+7, &end, 0);
1021                         if (arg[7] && !*end) {
1022                                 listen_port = n;
1023                                 continue;
1024                         }
1025                 }
1026                 if (!strcmp(arg, "--inetd")) {
1027                         inetd_mode = 1;
1028                         log_syslog = 1;
1029                         continue;
1030                 }
1031                 if (!strcmp(arg, "--verbose")) {
1032                         verbose = 1;
1033                         continue;
1034                 }
1035                 if (!strcmp(arg, "--syslog")) {
1036                         log_syslog = 1;
1037                         continue;
1038                 }
1039                 if (!strcmp(arg, "--export-all")) {
1040                         export_all_trees = 1;
1041                         continue;
1042                 }
1043                 if (!prefixcmp(arg, "--timeout=")) {
1044                         timeout = atoi(arg+10);
1045                         continue;
1046                 }
1047                 if (!prefixcmp(arg, "--init-timeout=")) {
1048                         init_timeout = atoi(arg+15);
1049                         continue;
1050                 }
1051                 if (!prefixcmp(arg, "--max-connections=")) {
1052                         max_connections = atoi(arg+18);
1053                         if (max_connections < 0)
1054                                 max_connections = 0;            /* unlimited */
1055                         continue;
1056                 }
1057                 if (!strcmp(arg, "--strict-paths")) {
1058                         strict_paths = 1;
1059                         continue;
1060                 }
1061                 if (!prefixcmp(arg, "--base-path=")) {
1062                         base_path = arg+12;
1063                         continue;
1064                 }
1065                 if (!strcmp(arg, "--base-path-relaxed")) {
1066                         base_path_relaxed = 1;
1067                         continue;
1068                 }
1069                 if (!prefixcmp(arg, "--interpolated-path=")) {
1070                         interpolated_path = arg+20;
1071                         continue;
1072                 }
1073                 if (!strcmp(arg, "--reuseaddr")) {
1074                         reuseaddr = 1;
1075                         continue;
1076                 }
1077                 if (!strcmp(arg, "--user-path")) {
1078                         user_path = "";
1079                         continue;
1080                 }
1081                 if (!prefixcmp(arg, "--user-path=")) {
1082                         user_path = arg + 12;
1083                         continue;
1084                 }
1085                 if (!prefixcmp(arg, "--pid-file=")) {
1086                         pid_file = arg + 11;
1087                         continue;
1088                 }
1089                 if (!strcmp(arg, "--detach")) {
1090                         detach = 1;
1091                         log_syslog = 1;
1092                         continue;
1093                 }
1094                 if (!prefixcmp(arg, "--user=")) {
1095                         user_name = arg + 7;
1096                         continue;
1097                 }
1098                 if (!prefixcmp(arg, "--group=")) {
1099                         group_name = arg + 8;
1100                         continue;
1101                 }
1102                 if (!prefixcmp(arg, "--enable=")) {
1103                         enable_service(arg + 9, 1);
1104                         continue;
1105                 }
1106                 if (!prefixcmp(arg, "--disable=")) {
1107                         enable_service(arg + 10, 0);
1108                         continue;
1109                 }
1110                 if (!prefixcmp(arg, "--allow-override=")) {
1111                         make_service_overridable(arg + 17, 1);
1112                         continue;
1113                 }
1114                 if (!prefixcmp(arg, "--forbid-override=")) {
1115                         make_service_overridable(arg + 18, 0);
1116                         continue;
1117                 }
1118                 if (!strcmp(arg, "--")) {
1119                         ok_paths = &argv[i+1];
1120                         break;
1121                 } else if (arg[0] != '-') {
1122                         ok_paths = &argv[i];
1123                         break;
1124                 }
1125
1126                 usage(daemon_usage);
1127         }
1128
1129         if (log_syslog) {
1130                 openlog("git-daemon", LOG_PID, LOG_DAEMON);
1131                 set_die_routine(daemon_die);
1132         } else
1133                 /* avoid splitting a message in the middle */
1134                 setvbuf(stderr, NULL, _IOLBF, 0);
1135
1136         if (inetd_mode && (group_name || user_name))
1137                 die("--user and --group are incompatible with --inetd");
1138
1139         if (inetd_mode && (listen_port || listen_addr))
1140                 die("--listen= and --port= are incompatible with --inetd");
1141         else if (listen_port == 0)
1142                 listen_port = DEFAULT_GIT_PORT;
1143
1144         if (group_name && !user_name)
1145                 die("--group supplied without --user");
1146
1147         if (user_name) {
1148                 pass = getpwnam(user_name);
1149                 if (!pass)
1150                         die("user not found - %s", user_name);
1151
1152                 if (!group_name)
1153                         gid = pass->pw_gid;
1154                 else {
1155                         group = getgrnam(group_name);
1156                         if (!group)
1157                                 die("group not found - %s", group_name);
1158
1159                         gid = group->gr_gid;
1160                 }
1161         }
1162
1163         if (strict_paths && (!ok_paths || !*ok_paths))
1164                 die("option --strict-paths requires a whitelist");
1165
1166         if (base_path && !is_directory(base_path))
1167                 die("base-path '%s' does not exist or is not a directory",
1168                     base_path);
1169
1170         if (inetd_mode) {
1171                 struct sockaddr_storage ss;
1172                 struct sockaddr *peer = (struct sockaddr *)&ss;
1173                 socklen_t slen = sizeof(ss);
1174
1175                 if (!freopen("/dev/null", "w", stderr))
1176                         die_errno("failed to redirect stderr to /dev/null");
1177
1178                 if (getpeername(0, peer, &slen))
1179                         peer = NULL;
1180
1181                 return execute(peer);
1182         }
1183
1184         if (detach) {
1185                 daemonize();
1186                 loginfo("Ready to rumble");
1187         }
1188         else
1189                 sanitize_stdfds();
1190
1191         if (pid_file)
1192                 store_pid(pid_file);
1193
1194         return serve(listen_addr, listen_port, pass, gid);
1195 }