daemon.c

   1 #include "cache.h"
   2 #include "pkt-line.h"
   3 #include "run-command.h"
   4 #include "strbuf.h"
   5 #include "string-list.h"
   6
   7 #ifndef HOST_NAME_MAX
   8 #define HOST_NAME_MAX 256
   9 #endif
  10
  11 #ifdef NO_INITGROUPS
  12 #define initgroups(x, y) (0) /* nothing */
  13 #endif
  14
  15 static int log_syslog;
  16 static int verbose;
  17 static int reuseaddr;
  18 static int informative_errors;
  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] [--pid-file=<file>]\n"
  27 "           [--(enable|disable|allow-override|forbid-override)=<service>]\n"
  28 "           [--access-hook=<path>]\n"
  29 "           [--inetd | [--listen=<host_or_ipaddr>] [--port=<n>]\n"
  30 "                      [--detach] [--user=<user> [--group=<group>]]\n"
  31 "           [<directory>...]";
  32
  33 /* List of acceptable pathname prefixes */
  34 static const 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 const char *base_path;
  42 static const char *interpolated_path;
  43 static int base_path_relaxed;
  44
  45 /* If defined, ~user notation is allowed and the string is inserted
  46  * after ~user/.  E.g. a request to git://host/~alice/frotz would
  47  * go to /home/alice/pub_git/frotz with --user-path=pub_git.
  48  */
  49 static const char *user_path;
  50
  51 /* Timeout, and initial timeout */
  52 static unsigned int timeout;
  53 static unsigned int init_timeout;
  54
  55 struct hostinfo {
  56         struct strbuf hostname;
  57         struct strbuf canon_hostname;
  58         struct strbuf ip_address;
  59         struct strbuf tcp_port;
  60         unsigned int hostname_lookup_done:1;
  61         unsigned int saw_extended_args:1;
  62 };
  63
  64 static void lookup_hostname(struct hostinfo *hi);
  65
  66 static const char *get_canon_hostname(struct hostinfo *hi)
  67 {
  68         lookup_hostname(hi);
  69         return hi->canon_hostname.buf;
  70 }
  71
  72 static const char *get_ip_address(struct hostinfo *hi)
  73 {
  74         lookup_hostname(hi);
  75         return hi->ip_address.buf;
  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 buffered mode, the
  87                  * logging of different processes will not overlap
  88                  * unless they overflow the (rather big) buffers.
  89                  */
  90                 fprintf(stderr, "[%"PRIuMAX"] ", (uintmax_t)getpid());
  91                 vfprintf(stderr, err, params);
  92                 fputc('\n', stderr);
  93                 fflush(stderr);
  94         }
  95 }
  96
  97 __attribute__((format (printf, 1, 2)))
  98 static void logerror(const char *err, ...)
  99 {
 100         va_list params;
 101         va_start(params, err);
 102         logreport(LOG_ERR, err, params);
 103         va_end(params);
 104 }
 105
 106 __attribute__((format (printf, 1, 2)))
 107 static void loginfo(const char *err, ...)
 108 {
 109         va_list params;
 110         if (!verbose)
 111                 return;
 112         va_start(params, err);
 113         logreport(LOG_INFO, err, params);
 114         va_end(params);
 115 }
 116
 117 static void NORETURN daemon_die(const char *err, va_list params)
 118 {
 119         logreport(LOG_ERR, err, params);
 120         exit(1);
 121 }
 122
 123 struct expand_path_context {
 124         const char *directory;
 125         struct hostinfo *hostinfo;
 126 };
 127
 128 static size_t expand_path(struct strbuf *sb, const char *placeholder, void *ctx)
 129 {
 130         struct expand_path_context *context = ctx;
 131         struct hostinfo *hi = context->hostinfo;
 132
 133         switch (placeholder[0]) {
 134         case 'H':
 135                 strbuf_addbuf(sb, &hi->hostname);
 136                 return 1;
 137         case 'C':
 138                 if (placeholder[1] == 'H') {
 139                         strbuf_addstr(sb, get_canon_hostname(hi));
 140                         return 2;
 141                 }
 142                 break;
 143         case 'I':
 144                 if (placeholder[1] == 'P') {
 145                         strbuf_addstr(sb, get_ip_address(hi));
 146                         return 2;
 147                 }
 148                 break;
 149         case 'P':
 150                 strbuf_addbuf(sb, &hi->tcp_port);
 151                 return 1;
 152         case 'D':
 153                 strbuf_addstr(sb, context->directory);
 154                 return 1;
 155         }
 156         return 0;
 157 }
 158
 159 static const char *path_ok(const char *directory, struct hostinfo *hi)
 160 {
 161         static char rpath[PATH_MAX];
 162         static char interp_path[PATH_MAX];
 163         size_t rlen;
 164         const char *path;
 165         const char *dir;
 166
 167         dir = directory;
 168
 169         if (daemon_avoid_alias(dir)) {
 170                 logerror("'%s': aliased", dir);
 171                 return NULL;
 172         }
 173
 174         if (*dir == '~') {
 175                 if (!user_path) {
 176                         logerror("'%s': User-path not allowed", dir);
 177                         return NULL;
 178                 }
 179                 if (*user_path) {
 180                         /* Got either "~alice" or "~alice/foo";
 181                          * rewrite them to "~alice/%s" or
 182                          * "~alice/%s/foo".
 183                          */
 184                         int namlen, restlen = strlen(dir);
 185                         const char *slash = strchr(dir, '/');
 186                         if (!slash)
 187                                 slash = dir + restlen;
 188                         namlen = slash - dir;
 189                         restlen -= namlen;
 190                         loginfo("userpath <%s>, request <%s>, namlen %d, restlen %d, slash <%s>", user_path, dir, namlen, restlen, slash);
 191                         rlen = snprintf(rpath, sizeof(rpath), "%.*s/%s%.*s",
 192                                         namlen, dir, user_path, restlen, slash);
 193                         if (rlen >= sizeof(rpath)) {
 194                                 logerror("user-path too large: %s", rpath);
 195                                 return NULL;
 196                         }
 197                         dir = rpath;
 198                 }
 199         }
 200         else if (interpolated_path && hi->saw_extended_args) {
 201                 struct strbuf expanded_path = STRBUF_INIT;
 202                 struct expand_path_context context;
 203
 204                 context.directory = directory;
 205                 context.hostinfo = hi;
 206
 207                 if (*dir != '/') {
 208                         /* Allow only absolute */
 209                         logerror("'%s': Non-absolute path denied (interpolated-path active)", dir);
 210                         return NULL;
 211                 }
 212
 213                 strbuf_expand(&expanded_path, interpolated_path,
 214                               expand_path, &context);
 215
 216                 rlen = strlcpy(interp_path, expanded_path.buf,
 217                                sizeof(interp_path));
 218                 if (rlen >= sizeof(interp_path)) {
 219                         logerror("interpolated path too large: %s",
 220                                  interp_path);
 221                         return NULL;
 222                 }
 223
 224                 strbuf_release(&expanded_path);
 225                 loginfo("Interpolated dir '%s'", interp_path);
 226
 227                 dir = interp_path;
 228         }
 229         else if (base_path) {
 230                 if (*dir != '/') {
 231                         /* Allow only absolute */
 232                         logerror("'%s': Non-absolute path denied (base-path active)", dir);
 233                         return NULL;
 234                 }
 235                 rlen = snprintf(rpath, sizeof(rpath), "%s%s", base_path, dir);
 236                 if (rlen >= sizeof(rpath)) {
 237                         logerror("base-path too large: %s", rpath);
 238                         return NULL;
 239                 }
 240                 dir = rpath;
 241         }
 242
 243         path = enter_repo(dir, strict_paths);
 244         if (!path && base_path && base_path_relaxed) {
 245                 /*
 246                  * if we fail and base_path_relaxed is enabled, try without
 247                  * prefixing the base path
 248                  */
 249                 dir = directory;
 250                 path = enter_repo(dir, strict_paths);
 251         }
 252
 253         if (!path) {
 254                 logerror("'%s' does not appear to be a git repository", dir);
 255                 return NULL;
 256         }
 257
 258         if ( ok_paths && *ok_paths ) {
 259                 const char **pp;
 260                 int pathlen = strlen(path);
 261
 262                 /* The validation is done on the paths after enter_repo
 263                  * appends optional {.git,.git/.git} and friends, but
 264                  * it does not use getcwd().  So if your /pub is
 265                  * a symlink to /mnt/pub, you can whitelist /pub and
 266                  * do not have to say /mnt/pub.
 267                  * Do not say /pub/.
 268                  */
 269                 for ( pp = ok_paths ; *pp ; pp++ ) {
 270                         int len = strlen(*pp);
 271                         if (len <= pathlen &&
 272                             !memcmp(*pp, path, len) &&
 273                             (path[len] == '\0' ||
 274                              (!strict_paths && path[len] == '/')))
 275                                 return path;
 276                 }
 277         }
 278         else {
 279                 /* be backwards compatible */
 280                 if (!strict_paths)
 281                         return path;
 282         }
 283
 284         logerror("'%s': not in whitelist", path);
 285         return NULL;            /* Fallthrough. Deny by default */
 286 }
 287
 288 typedef int (*daemon_service_fn)(void);
 289 struct daemon_service {
 290         const char *name;
 291         const char *config_name;
 292         daemon_service_fn fn;
 293         int enabled;
 294         int overridable;
 295 };
 296
 297 static int daemon_error(const char *dir, const char *msg)
 298 {
 299         if (!informative_errors)
 300                 msg = "access denied or repository not exported";
 301         packet_write(1, "ERR %s: %s", msg, dir);
 302         return -1;
 303 }
 304
 305 static const char *access_hook;
 306
 307 static int run_access_hook(struct daemon_service *service, const char *dir,
 308                            const char *path, struct hostinfo *hi)
 309 {
 310         struct child_process child = CHILD_PROCESS_INIT;
 311         struct strbuf buf = STRBUF_INIT;
 312         const char *argv[8];
 313         const char **arg = argv;
 314         char *eol;
 315         int seen_errors = 0;
 316
 317         *arg++ = access_hook;
 318         *arg++ = service->name;
 319         *arg++ = path;
 320         *arg++ = hi->hostname.buf;
 321         *arg++ = get_canon_hostname(hi);
 322         *arg++ = get_ip_address(hi);
 323         *arg++ = hi->tcp_port.buf;
 324         *arg = NULL;
 325
 326         child.use_shell = 1;
 327         child.argv = argv;
 328         child.no_stdin = 1;
 329         child.no_stderr = 1;
 330         child.out = -1;
 331         if (start_command(&child)) {
 332                 logerror("daemon access hook '%s' failed to start",
 333                          access_hook);
 334                 goto error_return;
 335         }
 336         if (strbuf_read(&buf, child.out, 0) < 0) {
 337                 logerror("failed to read from pipe to daemon access hook '%s'",
 338                          access_hook);
 339                 strbuf_reset(&buf);
 340                 seen_errors = 1;
 341         }
 342         if (close(child.out) < 0) {
 343                 logerror("failed to close pipe to daemon access hook '%s'",
 344                          access_hook);
 345                 seen_errors = 1;
 346         }
 347         if (finish_command(&child))
 348                 seen_errors = 1;
 349
 350         if (!seen_errors) {
 351                 strbuf_release(&buf);
 352                 return 0;
 353         }
 354
 355 error_return:
 356         strbuf_ltrim(&buf);
 357         if (!buf.len)
 358                 strbuf_addstr(&buf, "service rejected");
 359         eol = strchr(buf.buf, '\n');
 360         if (eol)
 361                 *eol = '\0';
 362         errno = EACCES;
 363         daemon_error(dir, buf.buf);
 364         strbuf_release(&buf);
 365         return -1;
 366 }
 367
 368 static int run_service(const char *dir, struct daemon_service *service,
 369                        struct hostinfo *hi)
 370 {
 371         const char *path;
 372         int enabled = service->enabled;
 373         struct strbuf var = STRBUF_INIT;
 374
 375         loginfo("Request %s for '%s'", service->name, dir);
 376
 377         if (!enabled && !service->overridable) {
 378                 logerror("'%s': service not enabled.", service->name);
 379                 errno = EACCES;
 380                 return daemon_error(dir, "service not enabled");
 381         }
 382
 383         if (!(path = path_ok(dir, hi)))
 384                 return daemon_error(dir, "no such repository");
 385
 386         /*
 387          * Security on the cheap.
 388          *
 389          * We want a readable HEAD, usable "objects" directory, and
 390          * a "git-daemon-export-ok" flag that says that the other side
 391          * is ok with us doing this.
 392          *
 393          * path_ok() uses enter_repo() and does whitelist checking.
 394          * We only need to make sure the repository is exported.
 395          */
 396
 397         if (!export_all_trees && access("git-daemon-export-ok", F_OK)) {
 398                 logerror("'%s': repository not exported.", path);
 399                 errno = EACCES;
 400                 return daemon_error(dir, "repository not exported");
 401         }
 402
 403         if (service->overridable) {
 404                 strbuf_addf(&var, "daemon.%s", service->config_name);
 405                 git_config_get_bool(var.buf, &enabled);
 406                 strbuf_release(&var);
 407         }
 408         if (!enabled) {
 409                 logerror("'%s': service not enabled for '%s'",
 410                          service->name, path);
 411                 errno = EACCES;
 412                 return daemon_error(dir, "service not enabled");
 413         }
 414
 415         /*
 416          * Optionally, a hook can choose to deny access to the
 417          * repository depending on the phase of the moon.
 418          */
 419         if (access_hook && run_access_hook(service, dir, path, hi))
 420                 return -1;
 421
 422         /*
 423          * We'll ignore SIGTERM from now on, we have a
 424          * good client.
 425          */
 426         signal(SIGTERM, SIG_IGN);
 427
 428         return service->fn();
 429 }
 430
 431 static void copy_to_log(int fd)
 432 {
 433         struct strbuf line = STRBUF_INIT;
 434         FILE *fp;
 435
 436         fp = fdopen(fd, "r");
 437         if (fp == NULL) {
 438                 logerror("fdopen of error channel failed");
 439                 close(fd);
 440                 return;
 441         }
 442
 443         while (strbuf_getline_lf(&line, fp) != EOF) {
 444                 logerror("%s", line.buf);
 445                 strbuf_setlen(&line, 0);
 446         }
 447
 448         strbuf_release(&line);
 449         fclose(fp);
 450 }
 451
 452 static int run_service_command(const char **argv)
 453 {
 454         struct child_process cld = CHILD_PROCESS_INIT;
 455
 456         cld.argv = argv;
 457         cld.git_cmd = 1;
 458         cld.err = -1;
 459         if (start_command(&cld))
 460                 return -1;
 461
 462         close(0);
 463         close(1);
 464
 465         copy_to_log(cld.err);
 466
 467         return finish_command(&cld);
 468 }
 469
 470 static int upload_pack(void)
 471 {
 472         /* Timeout as string */
 473         char timeout_buf[64];
 474         const char *argv[] = { "upload-pack", "--strict", NULL, ".", NULL };
 475
 476         argv[2] = timeout_buf;
 477
 478         snprintf(timeout_buf, sizeof timeout_buf, "--timeout=%u", timeout);
 479         return run_service_command(argv);
 480 }
 481
 482 static int upload_archive(void)
 483 {
 484         static const char *argv[] = { "upload-archive", ".", NULL };
 485         return run_service_command(argv);
 486 }
 487
 488 static int receive_pack(void)
 489 {
 490         static const char *argv[] = { "receive-pack", ".", NULL };
 491         return run_service_command(argv);
 492 }
 493
 494 static struct daemon_service daemon_service[] = {
 495         { "upload-archive", "uploadarch", upload_archive, 0, 1 },
 496         { "upload-pack", "uploadpack", upload_pack, 1, 1 },
 497         { "receive-pack", "receivepack", receive_pack, 0, 1 },
 498 };
 499
 500 static void enable_service(const char *name, int ena)
 501 {
 502         int i;
 503         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 504                 if (!strcmp(daemon_service[i].name, name)) {
 505                         daemon_service[i].enabled = ena;
 506                         return;
 507                 }
 508         }
 509         die("No such service %s", name);
 510 }
 511
 512 static void make_service_overridable(const char *name, int ena)
 513 {
 514         int i;
 515         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 516                 if (!strcmp(daemon_service[i].name, name)) {
 517                         daemon_service[i].overridable = ena;
 518                         return;
 519                 }
 520         }
 521         die("No such service %s", name);
 522 }
 523
 524 static void parse_host_and_port(char *hostport, char **host,
 525         char **port)
 526 {
 527         if (*hostport == '[') {
 528                 char *end;
 529
 530                 end = strchr(hostport, ']');
 531                 if (!end)
 532                         die("Invalid request ('[' without ']')");
 533                 *end = '\0';
 534                 *host = hostport + 1;
 535                 if (!end[1])
 536                         *port = NULL;
 537                 else if (end[1] == ':')
 538                         *port = end + 2;
 539                 else
 540                         die("Garbage after end of host part");
 541         } else {
 542                 *host = hostport;
 543                 *port = strrchr(hostport, ':');
 544                 if (*port) {
 545                         **port = '\0';
 546                         ++*port;
 547                 }
 548         }
 549 }
 550
 551 /*
 552  * Sanitize a string from the client so that it's OK to be inserted into a
 553  * filesystem path. Specifically, we disallow slashes, runs of "..", and
 554  * trailing and leading dots, which means that the client cannot escape
 555  * our base path via ".." traversal.
 556  */
 557 static void sanitize_client(struct strbuf *out, const char *in)
 558 {
 559         for (; *in; in++) {
 560                 if (*in == '/')
 561                         continue;
 562                 if (*in == '.' && (!out->len || out->buf[out->len - 1] == '.'))
 563                         continue;
 564                 strbuf_addch(out, *in);
 565         }
 566
 567         while (out->len && out->buf[out->len - 1] == '.')
 568                 strbuf_setlen(out, out->len - 1);
 569 }
 570
 571 /*
 572  * Like sanitize_client, but we also perform any canonicalization
 573  * to make life easier on the admin.
 574  */
 575 static void canonicalize_client(struct strbuf *out, const char *in)
 576 {
 577         sanitize_client(out, in);
 578         strbuf_tolower(out);
 579 }
 580
 581 /*
 582  * Read the host as supplied by the client connection.
 583  */
 584 static void parse_host_arg(struct hostinfo *hi, char *extra_args, int buflen)
 585 {
 586         char *val;
 587         int vallen;
 588         char *end = extra_args + buflen;
 589
 590         if (extra_args < end && *extra_args) {
 591                 hi->saw_extended_args = 1;
 592                 if (strncasecmp("host=", extra_args, 5) == 0) {
 593                         val = extra_args + 5;
 594                         vallen = strlen(val) + 1;
 595                         if (*val) {
 596                                 /* Split <host>:<port> at colon. */
 597                                 char *host;
 598                                 char *port;
 599                                 parse_host_and_port(val, &host, &port);
 600                                 if (port)
 601                                         sanitize_client(&hi->tcp_port, port);
 602                                 canonicalize_client(&hi->hostname, host);
 603                                 hi->hostname_lookup_done = 0;
 604                         }
 605
 606                         /* On to the next one */
 607                         extra_args = val + vallen;
 608                 }
 609                 if (extra_args < end && *extra_args)
 610                         die("Invalid request");
 611         }
 612 }
 613
 614 /*
 615  * Locate canonical hostname and its IP address.
 616  */
 617 static void lookup_hostname(struct hostinfo *hi)
 618 {
 619         if (!hi->hostname_lookup_done && hi->hostname.len) {
 620 #ifndef NO_IPV6
 621                 struct addrinfo hints;
 622                 struct addrinfo *ai;
 623                 int gai;
 624                 static char addrbuf[HOST_NAME_MAX + 1];
 625
 626                 memset(&hints, 0, sizeof(hints));
 627                 hints.ai_flags = AI_CANONNAME;
 628
 629                 gai = getaddrinfo(hi->hostname.buf, NULL, &hints, &ai);
 630                 if (!gai) {
 631                         struct sockaddr_in *sin_addr = (void *)ai->ai_addr;
 632
 633                         inet_ntop(AF_INET, &sin_addr->sin_addr,
 634                                   addrbuf, sizeof(addrbuf));
 635                         strbuf_addstr(&hi->ip_address, addrbuf);
 636
 637                         if (ai->ai_canonname)
 638                                 sanitize_client(&hi->canon_hostname,
 639                                                 ai->ai_canonname);
 640                         else
 641                                 strbuf_addbuf(&hi->canon_hostname,
 642                                               &hi->ip_address);
 643
 644                         freeaddrinfo(ai);
 645                 }
 646 #else
 647                 struct hostent *hent;
 648                 struct sockaddr_in sa;
 649                 char **ap;
 650                 static char addrbuf[HOST_NAME_MAX + 1];
 651
 652                 hent = gethostbyname(hi->hostname.buf);
 653                 if (hent) {
 654                         ap = hent->h_addr_list;
 655                         memset(&sa, 0, sizeof sa);
 656                         sa.sin_family = hent->h_addrtype;
 657                         sa.sin_port = htons(0);
 658                         memcpy(&sa.sin_addr, *ap, hent->h_length);
 659
 660                         inet_ntop(hent->h_addrtype, &sa.sin_addr,
 661                                   addrbuf, sizeof(addrbuf));
 662
 663                         sanitize_client(&hi->canon_hostname, hent->h_name);
 664                         strbuf_addstr(&hi->ip_address, addrbuf);
 665                 }
 666 #endif
 667                 hi->hostname_lookup_done = 1;
 668         }
 669 }
 670
 671 static void hostinfo_init(struct hostinfo *hi)
 672 {
 673         memset(hi, 0, sizeof(*hi));
 674         strbuf_init(&hi->hostname, 0);
 675         strbuf_init(&hi->canon_hostname, 0);
 676         strbuf_init(&hi->ip_address, 0);
 677         strbuf_init(&hi->tcp_port, 0);
 678 }
 679
 680 static void hostinfo_clear(struct hostinfo *hi)
 681 {
 682         strbuf_release(&hi->hostname);
 683         strbuf_release(&hi->canon_hostname);
 684         strbuf_release(&hi->ip_address);
 685         strbuf_release(&hi->tcp_port);
 686 }
 687
 688 static void set_keep_alive(int sockfd)
 689 {
 690         int ka = 1;
 691
 692         if (setsockopt(sockfd, SOL_SOCKET, SO_KEEPALIVE, &ka, sizeof(ka)) < 0) {
 693                 if (errno != ENOTSOCK)
 694                         logerror("unable to set SO_KEEPALIVE on socket: %s",
 695                                 strerror(errno));
 696         }
 697 }
 698
 699 static int execute(void)
 700 {
 701         char *line = packet_buffer;
 702         int pktlen, len, i;
 703         char *addr = getenv("REMOTE_ADDR"), *port = getenv("REMOTE_PORT");
 704         struct hostinfo hi;
 705
 706         hostinfo_init(&hi);
 707
 708         if (addr)
 709                 loginfo("Connection from %s:%s", addr, port);
 710
 711         set_keep_alive(0);
 712         alarm(init_timeout ? init_timeout : timeout);
 713         pktlen = packet_read(0, NULL, NULL, packet_buffer, sizeof(packet_buffer), 0);
 714         alarm(0);
 715
 716         len = strlen(line);
 717         if (pktlen != len)
 718                 loginfo("Extended attributes (%d bytes) exist <%.*s>",
 719                         (int) pktlen - len,
 720                         (int) pktlen - len, line + len + 1);
 721         if (len && line[len-1] == '\n') {
 722                 line[--len] = 0;
 723                 pktlen--;
 724         }
 725
 726         if (len != pktlen)
 727                 parse_host_arg(&hi, line + len + 1, pktlen - len - 1);
 728
 729         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 730                 struct daemon_service *s = &(daemon_service[i]);
 731                 const char *arg;
 732
 733                 if (skip_prefix(line, "git-", &arg) &&
 734                     skip_prefix(arg, s->name, &arg) &&
 735                     *arg++ == ' ') {
 736                         /*
 737                          * Note: The directory here is probably context sensitive,
 738                          * and might depend on the actual service being performed.
 739                          */
 740                         int rc = run_service(arg, s, &hi);
 741                         hostinfo_clear(&hi);
 742                         return rc;
 743                 }
 744         }
 745
 746         hostinfo_clear(&hi);
 747         logerror("Protocol error: '%s'", line);
 748         return -1;
 749 }
 750
 751 static int addrcmp(const struct sockaddr_storage *s1,
 752     const struct sockaddr_storage *s2)
 753 {
 754         const struct sockaddr *sa1 = (const struct sockaddr*) s1;
 755         const struct sockaddr *sa2 = (const struct sockaddr*) s2;
 756
 757         if (sa1->sa_family != sa2->sa_family)
 758                 return sa1->sa_family - sa2->sa_family;
 759         if (sa1->sa_family == AF_INET)
 760                 return memcmp(&((struct sockaddr_in *)s1)->sin_addr,
 761                     &((struct sockaddr_in *)s2)->sin_addr,
 762                     sizeof(struct in_addr));
 763 #ifndef NO_IPV6
 764         if (sa1->sa_family == AF_INET6)
 765                 return memcmp(&((struct sockaddr_in6 *)s1)->sin6_addr,
 766                     &((struct sockaddr_in6 *)s2)->sin6_addr,
 767                     sizeof(struct in6_addr));
 768 #endif
 769         return 0;
 770 }
 771
 772 static int max_connections = 32;
 773
 774 static unsigned int live_children;
 775
 776 static struct child {
 777         struct child *next;
 778         struct child_process cld;
 779         struct sockaddr_storage address;
 780 } *firstborn;
 781
 782 static void add_child(struct child_process *cld, struct sockaddr *addr, socklen_t addrlen)
 783 {
 784         struct child *newborn, **cradle;
 785
 786         newborn = xcalloc(1, sizeof(*newborn));
 787         live_children++;
 788         memcpy(&newborn->cld, cld, sizeof(*cld));
 789         memcpy(&newborn->address, addr, addrlen);
 790         for (cradle = &firstborn; *cradle; cradle = &(*cradle)->next)
 791                 if (!addrcmp(&(*cradle)->address, &newborn->address))
 792                         break;
 793         newborn->next = *cradle;
 794         *cradle = newborn;
 795 }
 796
 797 /*
 798  * This gets called if the number of connections grows
 799  * past "max_connections".
 800  *
 801  * We kill the newest connection from a duplicate IP.
 802  */
 803 static void kill_some_child(void)
 804 {
 805         const struct child *blanket, *next;
 806
 807         if (!(blanket = firstborn))
 808                 return;
 809
 810         for (; (next = blanket->next); blanket = next)
 811                 if (!addrcmp(&blanket->address, &next->address)) {
 812                         kill(blanket->cld.pid, SIGTERM);
 813                         break;
 814                 }
 815 }
 816
 817 static void check_dead_children(void)
 818 {
 819         int status;
 820         pid_t pid;
 821
 822         struct child **cradle, *blanket;
 823         for (cradle = &firstborn; (blanket = *cradle);)
 824                 if ((pid = waitpid(blanket->cld.pid, &status, WNOHANG)) > 1) {
 825                         const char *dead = "";
 826                         if (status)
 827                                 dead = " (with error)";
 828                         loginfo("[%"PRIuMAX"] Disconnected%s", (uintmax_t)pid, dead);
 829
 830                         /* remove the child */
 831                         *cradle = blanket->next;
 832                         live_children--;
 833                         child_process_clear(&blanket->cld);
 834                         free(blanket);
 835                 } else
 836                         cradle = &blanket->next;
 837 }
 838
 839 static struct argv_array cld_argv = ARGV_ARRAY_INIT;
 840 static void handle(int incoming, struct sockaddr *addr, socklen_t addrlen)
 841 {
 842         struct child_process cld = CHILD_PROCESS_INIT;
 843
 844         if (max_connections && live_children >= max_connections) {
 845                 kill_some_child();
 846                 sleep(1);  /* give it some time to die */
 847                 check_dead_children();
 848                 if (live_children >= max_connections) {
 849                         close(incoming);
 850                         logerror("Too many children, dropping connection");
 851                         return;
 852                 }
 853         }
 854
 855         if (addr->sa_family == AF_INET) {
 856                 char buf[128] = "";
 857                 struct sockaddr_in *sin_addr = (void *) addr;
 858                 inet_ntop(addr->sa_family, &sin_addr->sin_addr, buf, sizeof(buf));
 859                 argv_array_pushf(&cld.env_array, "REMOTE_ADDR=%s", buf);
 860                 argv_array_pushf(&cld.env_array, "REMOTE_PORT=%d",
 861                                  ntohs(sin_addr->sin_port));
 862 #ifndef NO_IPV6
 863         } else if (addr->sa_family == AF_INET6) {
 864                 char buf[128] = "";
 865                 struct sockaddr_in6 *sin6_addr = (void *) addr;
 866                 inet_ntop(AF_INET6, &sin6_addr->sin6_addr, buf, sizeof(buf));
 867                 argv_array_pushf(&cld.env_array, "REMOTE_ADDR=[%s]", buf);
 868                 argv_array_pushf(&cld.env_array, "REMOTE_PORT=%d",
 869                                  ntohs(sin6_addr->sin6_port));
 870 #endif
 871         }
 872
 873         cld.argv = cld_argv.argv;
 874         cld.in = incoming;
 875         cld.out = dup(incoming);
 876
 877         if (start_command(&cld))
 878                 logerror("unable to fork");
 879         else
 880                 add_child(&cld, addr, addrlen);
 881 }
 882
 883 static void child_handler(int signo)
 884 {
 885         /*
 886          * Otherwise empty handler because systemcalls will get interrupted
 887          * upon signal receipt
 888          * SysV needs the handler to be rearmed
 889          */
 890         signal(SIGCHLD, child_handler);
 891 }
 892
 893 static int set_reuse_addr(int sockfd)
 894 {
 895         int on = 1;
 896
 897         if (!reuseaddr)
 898                 return 0;
 899         return setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
 900                           &on, sizeof(on));
 901 }
 902
 903 struct socketlist {
 904         int *list;
 905         size_t nr;
 906         size_t alloc;
 907 };
 908
 909 static const char *ip2str(int family, struct sockaddr *sin, socklen_t len)
 910 {
 911 #ifdef NO_IPV6
 912         static char ip[INET_ADDRSTRLEN];
 913 #else
 914         static char ip[INET6_ADDRSTRLEN];
 915 #endif
 916
 917         switch (family) {
 918 #ifndef NO_IPV6
 919         case AF_INET6:
 920                 inet_ntop(family, &((struct sockaddr_in6*)sin)->sin6_addr, ip, len);
 921                 break;
 922 #endif
 923         case AF_INET:
 924                 inet_ntop(family, &((struct sockaddr_in*)sin)->sin_addr, ip, len);
 925                 break;
 926         default:
 927                 xsnprintf(ip, sizeof(ip), "<unknown>");
 928         }
 929         return ip;
 930 }
 931
 932 #ifndef NO_IPV6
 933
 934 static int setup_named_sock(char *listen_addr, int listen_port, struct socketlist *socklist)
 935 {
 936         int socknum = 0;
 937         char pbuf[NI_MAXSERV];
 938         struct addrinfo hints, *ai0, *ai;
 939         int gai;
 940         long flags;
 941
 942         xsnprintf(pbuf, sizeof(pbuf), "%d", listen_port);
 943         memset(&hints, 0, sizeof(hints));
 944         hints.ai_family = AF_UNSPEC;
 945         hints.ai_socktype = SOCK_STREAM;
 946         hints.ai_protocol = IPPROTO_TCP;
 947         hints.ai_flags = AI_PASSIVE;
 948
 949         gai = getaddrinfo(listen_addr, pbuf, &hints, &ai0);
 950         if (gai) {
 951                 logerror("getaddrinfo() for %s failed: %s", listen_addr, gai_strerror(gai));
 952                 return 0;
 953         }
 954
 955         for (ai = ai0; ai; ai = ai->ai_next) {
 956                 int sockfd;
 957
 958                 sockfd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
 959                 if (sockfd < 0)
 960                         continue;
 961                 if (sockfd >= FD_SETSIZE) {
 962                         logerror("Socket descriptor too large");
 963                         close(sockfd);
 964                         continue;
 965                 }
 966
 967 #ifdef IPV6_V6ONLY
 968                 if (ai->ai_family == AF_INET6) {
 969                         int on = 1;
 970                         setsockopt(sockfd, IPPROTO_IPV6, IPV6_V6ONLY,
 971                                    &on, sizeof(on));
 972                         /* Note: error is not fatal */
 973                 }
 974 #endif
 975
 976                 if (set_reuse_addr(sockfd)) {
 977                         logerror("Could not set SO_REUSEADDR: %s", strerror(errno));
 978                         close(sockfd);
 979                         continue;
 980                 }
 981
 982                 set_keep_alive(sockfd);
 983
 984                 if (bind(sockfd, ai->ai_addr, ai->ai_addrlen) < 0) {
 985                         logerror("Could not bind to %s: %s",
 986                                  ip2str(ai->ai_family, ai->ai_addr, ai->ai_addrlen),
 987                                  strerror(errno));
 988                         close(sockfd);
 989                         continue;       /* not fatal */
 990                 }
 991                 if (listen(sockfd, 5) < 0) {
 992                         logerror("Could not listen to %s: %s",
 993                                  ip2str(ai->ai_family, ai->ai_addr, ai->ai_addrlen),
 994                                  strerror(errno));
 995                         close(sockfd);
 996                         continue;       /* not fatal */
 997                 }
 998
 999                 flags = fcntl(sockfd, F_GETFD, 0);
1000                 if (flags >= 0)
1001                         fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
1002
1003                 ALLOC_GROW(socklist->list, socklist->nr + 1, socklist->alloc);
1004                 socklist->list[socklist->nr++] = sockfd;
1005                 socknum++;
1006         }
1007
1008         freeaddrinfo(ai0);
1009
1010         return socknum;
1011 }
1012
1013 #else /* NO_IPV6 */
1014
1015 static int setup_named_sock(char *listen_addr, int listen_port, struct socketlist *socklist)
1016 {
1017         struct sockaddr_in sin;
1018         int sockfd;
1019         long flags;
1020
1021         memset(&sin, 0, sizeof sin);
1022         sin.sin_family = AF_INET;
1023         sin.sin_port = htons(listen_port);
1024
1025         if (listen_addr) {
1026                 /* Well, host better be an IP address here. */
1027                 if (inet_pton(AF_INET, listen_addr, &sin.sin_addr.s_addr) <= 0)
1028                         return 0;
1029         } else {
1030                 sin.sin_addr.s_addr = htonl(INADDR_ANY);
1031         }
1032
1033         sockfd = socket(AF_INET, SOCK_STREAM, 0);
1034         if (sockfd < 0)
1035                 return 0;
1036
1037         if (set_reuse_addr(sockfd)) {
1038                 logerror("Could not set SO_REUSEADDR: %s", strerror(errno));
1039                 close(sockfd);
1040                 return 0;
1041         }
1042
1043         set_keep_alive(sockfd);
1044
1045         if ( bind(sockfd, (struct sockaddr *)&sin, sizeof sin) < 0 ) {
1046                 logerror("Could not bind to %s: %s",
1047                          ip2str(AF_INET, (struct sockaddr *)&sin, sizeof(sin)),
1048                          strerror(errno));
1049                 close(sockfd);
1050                 return 0;
1051         }
1052
1053         if (listen(sockfd, 5) < 0) {
1054                 logerror("Could not listen to %s: %s",
1055                          ip2str(AF_INET, (struct sockaddr *)&sin, sizeof(sin)),
1056                          strerror(errno));
1057                 close(sockfd);
1058                 return 0;
1059         }
1060
1061         flags = fcntl(sockfd, F_GETFD, 0);
1062         if (flags >= 0)
1063                 fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
1064
1065         ALLOC_GROW(socklist->list, socklist->nr + 1, socklist->alloc);
1066         socklist->list[socklist->nr++] = sockfd;
1067         return 1;
1068 }
1069
1070 #endif
1071
1072 static void socksetup(struct string_list *listen_addr, int listen_port, struct socketlist *socklist)
1073 {
1074         if (!listen_addr->nr)
1075                 setup_named_sock(NULL, listen_port, socklist);
1076         else {
1077                 int i, socknum;
1078                 for (i = 0; i < listen_addr->nr; i++) {
1079                         socknum = setup_named_sock(listen_addr->items[i].string,
1080                                                    listen_port, socklist);
1081
1082                         if (socknum == 0)
1083                                 logerror("unable to allocate any listen sockets for host %s on port %u",
1084                                          listen_addr->items[i].string, listen_port);
1085                 }
1086         }
1087 }
1088
1089 static int service_loop(struct socketlist *socklist)
1090 {
1091         struct pollfd *pfd;
1092         int i;
1093
1094         pfd = xcalloc(socklist->nr, sizeof(struct pollfd));
1095
1096         for (i = 0; i < socklist->nr; i++) {
1097                 pfd[i].fd = socklist->list[i];
1098                 pfd[i].events = POLLIN;
1099         }
1100
1101         signal(SIGCHLD, child_handler);
1102
1103         for (;;) {
1104                 int i;
1105
1106                 check_dead_children();
1107
1108                 if (poll(pfd, socklist->nr, -1) < 0) {
1109                         if (errno != EINTR) {
1110                                 logerror("Poll failed, resuming: %s",
1111                                       strerror(errno));
1112                                 sleep(1);
1113                         }
1114                         continue;
1115                 }
1116
1117                 for (i = 0; i < socklist->nr; i++) {
1118                         if (pfd[i].revents & POLLIN) {
1119                                 union {
1120                                         struct sockaddr sa;
1121                                         struct sockaddr_in sai;
1122 #ifndef NO_IPV6
1123                                         struct sockaddr_in6 sai6;
1124 #endif
1125                                 } ss;
1126                                 socklen_t sslen = sizeof(ss);
1127                                 int incoming = accept(pfd[i].fd, &ss.sa, &sslen);
1128                                 if (incoming < 0) {
1129                                         switch (errno) {
1130                                         case EAGAIN:
1131                                         case EINTR:
1132                                         case ECONNABORTED:
1133                                                 continue;
1134                                         default:
1135                                                 die_errno("accept returned");
1136                                         }
1137                                 }
1138                                 handle(incoming, &ss.sa, sslen);
1139                         }
1140                 }
1141         }
1142 }
1143
1144 #ifdef NO_POSIX_GOODIES
1145
1146 struct credentials;
1147
1148 static void drop_privileges(struct credentials *cred)
1149 {
1150         /* nothing */
1151 }
1152
1153 static struct credentials *prepare_credentials(const char *user_name,
1154     const char *group_name)
1155 {
1156         die("--user not supported on this platform");
1157 }
1158
1159 #else
1160
1161 struct credentials {
1162         struct passwd *pass;
1163         gid_t gid;
1164 };
1165
1166 static void drop_privileges(struct credentials *cred)
1167 {
1168         if (cred && (initgroups(cred->pass->pw_name, cred->gid) ||
1169             setgid (cred->gid) || setuid(cred->pass->pw_uid)))
1170                 die("cannot drop privileges");
1171 }
1172
1173 static struct credentials *prepare_credentials(const char *user_name,
1174     const char *group_name)
1175 {
1176         static struct credentials c;
1177
1178         c.pass = getpwnam(user_name);
1179         if (!c.pass)
1180                 die("user not found - %s", user_name);
1181
1182         if (!group_name)
1183                 c.gid = c.pass->pw_gid;
1184         else {
1185                 struct group *group = getgrnam(group_name);
1186                 if (!group)
1187                         die("group not found - %s", group_name);
1188
1189                 c.gid = group->gr_gid;
1190         }
1191
1192         return &c;
1193 }
1194 #endif
1195
1196 static int serve(struct string_list *listen_addr, int listen_port,
1197     struct credentials *cred)
1198 {
1199         struct socketlist socklist = { NULL, 0, 0 };
1200
1201         socksetup(listen_addr, listen_port, &socklist);
1202         if (socklist.nr == 0)
1203                 die("unable to allocate any listen sockets on port %u",
1204                     listen_port);
1205
1206         drop_privileges(cred);
1207
1208         loginfo("Ready to rumble");
1209
1210         return service_loop(&socklist);
1211 }
1212
1213 int cmd_main(int argc, const char **argv)
1214 {
1215         int listen_port = 0;
1216         struct string_list listen_addr = STRING_LIST_INIT_NODUP;
1217         int serve_mode = 0, inetd_mode = 0;
1218         const char *pid_file = NULL, *user_name = NULL, *group_name = NULL;
1219         int detach = 0;
1220         struct credentials *cred = NULL;
1221         int i;
1222
1223         for (i = 1; i < argc; i++) {
1224                 const char *arg = argv[i];
1225                 const char *v;
1226
1227                 if (skip_prefix(arg, "--listen=", &v)) {
1228                         string_list_append(&listen_addr, xstrdup_tolower(v));
1229                         continue;
1230                 }
1231                 if (skip_prefix(arg, "--port=", &v)) {
1232                         char *end;
1233                         unsigned long n;
1234                         n = strtoul(v, &end, 0);
1235                         if (*v && !*end) {
1236                                 listen_port = n;
1237                                 continue;
1238                         }
1239                 }
1240                 if (!strcmp(arg, "--serve")) {
1241                         serve_mode = 1;
1242                         continue;
1243                 }
1244                 if (!strcmp(arg, "--inetd")) {
1245                         inetd_mode = 1;
1246                         log_syslog = 1;
1247                         continue;
1248                 }
1249                 if (!strcmp(arg, "--verbose")) {
1250                         verbose = 1;
1251                         continue;
1252                 }
1253                 if (!strcmp(arg, "--syslog")) {
1254                         log_syslog = 1;
1255                         continue;
1256                 }
1257                 if (!strcmp(arg, "--export-all")) {
1258                         export_all_trees = 1;
1259                         continue;
1260                 }
1261                 if (skip_prefix(arg, "--access-hook=", &v)) {
1262                         access_hook = v;
1263                         continue;
1264                 }
1265                 if (skip_prefix(arg, "--timeout=", &v)) {
1266                         timeout = atoi(v);
1267                         continue;
1268                 }
1269                 if (skip_prefix(arg, "--init-timeout=", &v)) {
1270                         init_timeout = atoi(v);
1271                         continue;
1272                 }
1273                 if (skip_prefix(arg, "--max-connections=", &v)) {
1274                         max_connections = atoi(v);
1275                         if (max_connections < 0)
1276                                 max_connections = 0;            /* unlimited */
1277                         continue;
1278                 }
1279                 if (!strcmp(arg, "--strict-paths")) {
1280                         strict_paths = 1;
1281                         continue;
1282                 }
1283                 if (skip_prefix(arg, "--base-path=", &v)) {
1284                         base_path = v;
1285                         continue;
1286                 }
1287                 if (!strcmp(arg, "--base-path-relaxed")) {
1288                         base_path_relaxed = 1;
1289                         continue;
1290                 }
1291                 if (skip_prefix(arg, "--interpolated-path=", &v)) {
1292                         interpolated_path = v;
1293                         continue;
1294                 }
1295                 if (!strcmp(arg, "--reuseaddr")) {
1296                         reuseaddr = 1;
1297                         continue;
1298                 }
1299                 if (!strcmp(arg, "--user-path")) {
1300                         user_path = "";
1301                         continue;
1302                 }
1303                 if (skip_prefix(arg, "--user-path=", &v)) {
1304                         user_path = v;
1305                         continue;
1306                 }
1307                 if (skip_prefix(arg, "--pid-file=", &v)) {
1308                         pid_file = v;
1309                         continue;
1310                 }
1311                 if (!strcmp(arg, "--detach")) {
1312                         detach = 1;
1313                         log_syslog = 1;
1314                         continue;
1315                 }
1316                 if (skip_prefix(arg, "--user=", &v)) {
1317                         user_name = v;
1318                         continue;
1319                 }
1320                 if (skip_prefix(arg, "--group=", &v)) {
1321                         group_name = v;
1322                         continue;
1323                 }
1324                 if (skip_prefix(arg, "--enable=", &v)) {
1325                         enable_service(v, 1);
1326                         continue;
1327                 }
1328                 if (skip_prefix(arg, "--disable=", &v)) {
1329                         enable_service(v, 0);
1330                         continue;
1331                 }
1332                 if (skip_prefix(arg, "--allow-override=", &v)) {
1333                         make_service_overridable(v, 1);
1334                         continue;
1335                 }
1336                 if (skip_prefix(arg, "--forbid-override=", &v)) {
1337                         make_service_overridable(v, 0);
1338                         continue;
1339                 }
1340                 if (!strcmp(arg, "--informative-errors")) {
1341                         informative_errors = 1;
1342                         continue;
1343                 }
1344                 if (!strcmp(arg, "--no-informative-errors")) {
1345                         informative_errors = 0;
1346                         continue;
1347                 }
1348                 if (!strcmp(arg, "--")) {
1349                         ok_paths = &argv[i+1];
1350                         break;
1351                 } else if (arg[0] != '-') {
1352                         ok_paths = &argv[i];
1353                         break;
1354                 }
1355
1356                 usage(daemon_usage);
1357         }
1358
1359         if (log_syslog) {
1360                 openlog("git-daemon", LOG_PID, LOG_DAEMON);
1361                 set_die_routine(daemon_die);
1362         } else
1363                 /* avoid splitting a message in the middle */
1364                 setvbuf(stderr, NULL, _IOFBF, 4096);
1365
1366         if (inetd_mode && (detach || group_name || user_name))
1367                 die("--detach, --user and --group are incompatible with --inetd");
1368
1369         if (inetd_mode && (listen_port || (listen_addr.nr > 0)))
1370                 die("--listen= and --port= are incompatible with --inetd");
1371         else if (listen_port == 0)
1372                 listen_port = DEFAULT_GIT_PORT;
1373
1374         if (group_name && !user_name)
1375                 die("--group supplied without --user");
1376
1377         if (user_name)
1378                 cred = prepare_credentials(user_name, group_name);
1379
1380         if (strict_paths && (!ok_paths || !*ok_paths))
1381                 die("option --strict-paths requires a whitelist");
1382
1383         if (base_path && !is_directory(base_path))
1384                 die("base-path '%s' does not exist or is not a directory",
1385                     base_path);
1386
1387         if (inetd_mode) {
1388                 if (!freopen("/dev/null", "w", stderr))
1389                         die_errno("failed to redirect stderr to /dev/null");
1390         }
1391
1392         if (inetd_mode || serve_mode)
1393                 return execute();
1394
1395         if (detach) {
1396                 if (daemonize())
1397                         die("--detach not supported on this platform");
1398         }
1399
1400         if (pid_file)
1401                 write_file(pid_file, "%"PRIuMAX, (uintmax_t) getpid());
1402
1403         /* prepare argv for serving-processes */
1404         argv_array_push(&cld_argv, argv[0]); /* git-daemon */
1405         argv_array_push(&cld_argv, "--serve");
1406         for (i = 1; i < argc; ++i)
1407                 argv_array_push(&cld_argv, argv[i]);
1408
1409         return serve(&listen_addr, listen_port, cred);
1410 }