git.oblomov.eu Git - git/blob - daemon.c

   1 #include "cache.h"
   2 #include "config.h"
   3 #include "pkt-line.h"
   4 #include "run-command.h"
   5 #include "strbuf.h"
   6 #include "string-list.h"
   7
   8 #ifdef NO_INITGROUPS
   9 #define initgroups(x, y) (0) /* nothing */
  10 #endif
  11
  12 static int log_syslog;
  13 static int verbose;
  14 static int reuseaddr;
  15 static int informative_errors;
  16
  17 static const char daemon_usage[] =
  18 "git daemon [--verbose] [--syslog] [--export-all]\n"
  19 "           [--timeout=<n>] [--init-timeout=<n>] [--max-connections=<n>]\n"
  20 "           [--strict-paths] [--base-path=<path>] [--base-path-relaxed]\n"
  21 "           [--user-path | --user-path=<path>]\n"
  22 "           [--interpolated-path=<path>]\n"
  23 "           [--reuseaddr] [--pid-file=<file>]\n"
  24 "           [--(enable|disable|allow-override|forbid-override)=<service>]\n"
  25 "           [--access-hook=<path>]\n"
  26 "           [--inetd | [--listen=<host_or_ipaddr>] [--port=<n>]\n"
  27 "                      [--detach] [--user=<user> [--group=<group>]]\n"
  28 "           [<directory>...]";
  29
  30 /* List of acceptable pathname prefixes */
  31 static const char **ok_paths;
  32 static int strict_paths;
  33
  34 /* If this is set, git-daemon-export-ok is not required */
  35 static int export_all_trees;
  36
  37 /* Take all paths relative to this one if non-NULL */
  38 static const char *base_path;
  39 static const char *interpolated_path;
  40 static int base_path_relaxed;
  41
  42 /* If defined, ~user notation is allowed and the string is inserted
  43  * after ~user/.  E.g. a request to git://host/~alice/frotz would
  44  * go to /home/alice/pub_git/frotz with --user-path=pub_git.
  45  */
  46 static const char *user_path;
  47
  48 /* Timeout, and initial timeout */
  49 static unsigned int timeout;
  50 static unsigned int init_timeout;
  51
  52 struct hostinfo {
  53         struct strbuf hostname;
  54         struct strbuf canon_hostname;
  55         struct strbuf ip_address;
  56         struct strbuf tcp_port;
  57         unsigned int hostname_lookup_done:1;
  58         unsigned int saw_extended_args:1;
  59 };
  60
  61 static void lookup_hostname(struct hostinfo *hi);
  62
  63 static const char *get_canon_hostname(struct hostinfo *hi)
  64 {
  65         lookup_hostname(hi);
  66         return hi->canon_hostname.buf;
  67 }
  68
  69 static const char *get_ip_address(struct hostinfo *hi)
  70 {
  71         lookup_hostname(hi);
  72         return hi->ip_address.buf;
  73 }
  74
  75 static void logreport(int priority, const char *err, va_list params)
  76 {
  77         if (log_syslog) {
  78                 char buf[1024];
  79                 vsnprintf(buf, sizeof(buf), err, params);
  80                 syslog(priority, "%s", buf);
  81         } else {
  82                 /*
  83                  * Since stderr is set to buffered mode, the
  84                  * logging of different processes will not overlap
  85                  * unless they overflow the (rather big) buffers.
  86                  */
  87                 fprintf(stderr, "[%"PRIuMAX"] ", (uintmax_t)getpid());
  88                 vfprintf(stderr, err, params);
  89                 fputc('\n', stderr);
  90                 fflush(stderr);
  91         }
  92 }
  93
  94 __attribute__((format (printf, 1, 2)))
  95 static void logerror(const char *err, ...)
  96 {
  97         va_list params;
  98         va_start(params, err);
  99         logreport(LOG_ERR, err, params);
 100         va_end(params);
 101 }
 102
 103 __attribute__((format (printf, 1, 2)))
 104 static void loginfo(const char *err, ...)
 105 {
 106         va_list params;
 107         if (!verbose)
 108                 return;
 109         va_start(params, err);
 110         logreport(LOG_INFO, err, params);
 111         va_end(params);
 112 }
 113
 114 static void NORETURN daemon_die(const char *err, va_list params)
 115 {
 116         logreport(LOG_ERR, err, params);
 117         exit(1);
 118 }
 119
 120 struct expand_path_context {
 121         const char *directory;
 122         struct hostinfo *hostinfo;
 123 };
 124
 125 static size_t expand_path(struct strbuf *sb, const char *placeholder, void *ctx)
 126 {
 127         struct expand_path_context *context = ctx;
 128         struct hostinfo *hi = context->hostinfo;
 129
 130         switch (placeholder[0]) {
 131         case 'H':
 132                 strbuf_addbuf(sb, &hi->hostname);
 133                 return 1;
 134         case 'C':
 135                 if (placeholder[1] == 'H') {
 136                         strbuf_addstr(sb, get_canon_hostname(hi));
 137                         return 2;
 138                 }
 139                 break;
 140         case 'I':
 141                 if (placeholder[1] == 'P') {
 142                         strbuf_addstr(sb, get_ip_address(hi));
 143                         return 2;
 144                 }
 145                 break;
 146         case 'P':
 147                 strbuf_addbuf(sb, &hi->tcp_port);
 148                 return 1;
 149         case 'D':
 150                 strbuf_addstr(sb, context->directory);
 151                 return 1;
 152         }
 153         return 0;
 154 }
 155
 156 static const char *path_ok(const char *directory, struct hostinfo *hi)
 157 {
 158         static char rpath[PATH_MAX];
 159         static char interp_path[PATH_MAX];
 160         size_t rlen;
 161         const char *path;
 162         const char *dir;
 163
 164         dir = directory;
 165
 166         if (daemon_avoid_alias(dir)) {
 167                 logerror("'%s': aliased", dir);
 168                 return NULL;
 169         }
 170
 171         if (*dir == '~') {
 172                 if (!user_path) {
 173                         logerror("'%s': User-path not allowed", dir);
 174                         return NULL;
 175                 }
 176                 if (*user_path) {
 177                         /* Got either "~alice" or "~alice/foo";
 178                          * rewrite them to "~alice/%s" or
 179                          * "~alice/%s/foo".
 180                          */
 181                         int namlen, restlen = strlen(dir);
 182                         const char *slash = strchr(dir, '/');
 183                         if (!slash)
 184                                 slash = dir + restlen;
 185                         namlen = slash - dir;
 186                         restlen -= namlen;
 187                         loginfo("userpath <%s>, request <%s>, namlen %d, restlen %d, slash <%s>", user_path, dir, namlen, restlen, slash);
 188                         rlen = snprintf(rpath, sizeof(rpath), "%.*s/%s%.*s",
 189                                         namlen, dir, user_path, restlen, slash);
 190                         if (rlen >= sizeof(rpath)) {
 191                                 logerror("user-path too large: %s", rpath);
 192                                 return NULL;
 193                         }
 194                         dir = rpath;
 195                 }
 196         }
 197         else if (interpolated_path && hi->saw_extended_args) {
 198                 struct strbuf expanded_path = STRBUF_INIT;
 199                 struct expand_path_context context;
 200
 201                 context.directory = directory;
 202                 context.hostinfo = hi;
 203
 204                 if (*dir != '/') {
 205                         /* Allow only absolute */
 206                         logerror("'%s': Non-absolute path denied (interpolated-path active)", dir);
 207                         return NULL;
 208                 }
 209
 210                 strbuf_expand(&expanded_path, interpolated_path,
 211                               expand_path, &context);
 212
 213                 rlen = strlcpy(interp_path, expanded_path.buf,
 214                                sizeof(interp_path));
 215                 if (rlen >= sizeof(interp_path)) {
 216                         logerror("interpolated path too large: %s",
 217                                  interp_path);
 218                         return NULL;
 219                 }
 220
 221                 strbuf_release(&expanded_path);
 222                 loginfo("Interpolated dir '%s'", interp_path);
 223
 224                 dir = interp_path;
 225         }
 226         else if (base_path) {
 227                 if (*dir != '/') {
 228                         /* Allow only absolute */
 229                         logerror("'%s': Non-absolute path denied (base-path active)", dir);
 230                         return NULL;
 231                 }
 232                 rlen = snprintf(rpath, sizeof(rpath), "%s%s", base_path, dir);
 233                 if (rlen >= sizeof(rpath)) {
 234                         logerror("base-path too large: %s", rpath);
 235                         return NULL;
 236                 }
 237                 dir = rpath;
 238         }
 239
 240         path = enter_repo(dir, strict_paths);
 241         if (!path && base_path && base_path_relaxed) {
 242                 /*
 243                  * if we fail and base_path_relaxed is enabled, try without
 244                  * prefixing the base path
 245                  */
 246                 dir = directory;
 247                 path = enter_repo(dir, strict_paths);
 248         }
 249
 250         if (!path) {
 251                 logerror("'%s' does not appear to be a git repository", dir);
 252                 return NULL;
 253         }
 254
 255         if ( ok_paths && *ok_paths ) {
 256                 const char **pp;
 257                 int pathlen = strlen(path);
 258
 259                 /* The validation is done on the paths after enter_repo
 260                  * appends optional {.git,.git/.git} and friends, but
 261                  * it does not use getcwd().  So if your /pub is
 262                  * a symlink to /mnt/pub, you can whitelist /pub and
 263                  * do not have to say /mnt/pub.
 264                  * Do not say /pub/.
 265                  */
 266                 for ( pp = ok_paths ; *pp ; pp++ ) {
 267                         int len = strlen(*pp);
 268                         if (len <= pathlen &&
 269                             !memcmp(*pp, path, len) &&
 270                             (path[len] == '\0' ||
 271                              (!strict_paths && path[len] == '/')))
 272                                 return path;
 273                 }
 274         }
 275         else {
 276                 /* be backwards compatible */
 277                 if (!strict_paths)
 278                         return path;
 279         }
 280
 281         logerror("'%s': not in whitelist", path);
 282         return NULL;            /* Fallthrough. Deny by default */
 283 }
 284
 285 typedef int (*daemon_service_fn)(void);
 286 struct daemon_service {
 287         const char *name;
 288         const char *config_name;
 289         daemon_service_fn fn;
 290         int enabled;
 291         int overridable;
 292 };
 293
 294 static int daemon_error(const char *dir, const char *msg)
 295 {
 296         if (!informative_errors)
 297                 msg = "access denied or repository not exported";
 298         packet_write_fmt(1, "ERR %s: %s", msg, dir);
 299         return -1;
 300 }
 301
 302 static const char *access_hook;
 303
 304 static int run_access_hook(struct daemon_service *service, const char *dir,
 305                            const char *path, struct hostinfo *hi)
 306 {
 307         struct child_process child = CHILD_PROCESS_INIT;
 308         struct strbuf buf = STRBUF_INIT;
 309         const char *argv[8];
 310         const char **arg = argv;
 311         char *eol;
 312         int seen_errors = 0;
 313
 314         *arg++ = access_hook;
 315         *arg++ = service->name;
 316         *arg++ = path;
 317         *arg++ = hi->hostname.buf;
 318         *arg++ = get_canon_hostname(hi);
 319         *arg++ = get_ip_address(hi);
 320         *arg++ = hi->tcp_port.buf;
 321         *arg = NULL;
 322
 323         child.use_shell = 1;
 324         child.argv = argv;
 325         child.no_stdin = 1;
 326         child.no_stderr = 1;
 327         child.out = -1;
 328         if (start_command(&child)) {
 329                 logerror("daemon access hook '%s' failed to start",
 330                          access_hook);
 331                 goto error_return;
 332         }
 333         if (strbuf_read(&buf, child.out, 0) < 0) {
 334                 logerror("failed to read from pipe to daemon access hook '%s'",
 335                          access_hook);
 336                 strbuf_reset(&buf);
 337                 seen_errors = 1;
 338         }
 339         if (close(child.out) < 0) {
 340                 logerror("failed to close pipe to daemon access hook '%s'",
 341                          access_hook);
 342                 seen_errors = 1;
 343         }
 344         if (finish_command(&child))
 345                 seen_errors = 1;
 346
 347         if (!seen_errors) {
 348                 strbuf_release(&buf);
 349                 return 0;
 350         }
 351
 352 error_return:
 353         strbuf_ltrim(&buf);
 354         if (!buf.len)
 355                 strbuf_addstr(&buf, "service rejected");
 356         eol = strchr(buf.buf, '\n');
 357         if (eol)
 358                 *eol = '\0';
 359         errno = EACCES;
 360         daemon_error(dir, buf.buf);
 361         strbuf_release(&buf);
 362         return -1;
 363 }
 364
 365 static int run_service(const char *dir, struct daemon_service *service,
 366                        struct hostinfo *hi)
 367 {
 368         const char *path;
 369         int enabled = service->enabled;
 370         struct strbuf var = STRBUF_INIT;
 371
 372         loginfo("Request %s for '%s'", service->name, dir);
 373
 374         if (!enabled && !service->overridable) {
 375                 logerror("'%s': service not enabled.", service->name);
 376                 errno = EACCES;
 377                 return daemon_error(dir, "service not enabled");
 378         }
 379
 380         if (!(path = path_ok(dir, hi)))
 381                 return daemon_error(dir, "no such repository");
 382
 383         /*
 384          * Security on the cheap.
 385          *
 386          * We want a readable HEAD, usable "objects" directory, and
 387          * a "git-daemon-export-ok" flag that says that the other side
 388          * is ok with us doing this.
 389          *
 390          * path_ok() uses enter_repo() and does whitelist checking.
 391          * We only need to make sure the repository is exported.
 392          */
 393
 394         if (!export_all_trees && access("git-daemon-export-ok", F_OK)) {
 395                 logerror("'%s': repository not exported.", path);
 396                 errno = EACCES;
 397                 return daemon_error(dir, "repository not exported");
 398         }
 399
 400         if (service->overridable) {
 401                 strbuf_addf(&var, "daemon.%s", service->config_name);
 402                 git_config_get_bool(var.buf, &enabled);
 403                 strbuf_release(&var);
 404         }
 405         if (!enabled) {
 406                 logerror("'%s': service not enabled for '%s'",
 407                          service->name, path);
 408                 errno = EACCES;
 409                 return daemon_error(dir, "service not enabled");
 410         }
 411
 412         /*
 413          * Optionally, a hook can choose to deny access to the
 414          * repository depending on the phase of the moon.
 415          */
 416         if (access_hook && run_access_hook(service, dir, path, hi))
 417                 return -1;
 418
 419         /*
 420          * We'll ignore SIGTERM from now on, we have a
 421          * good client.
 422          */
 423         signal(SIGTERM, SIG_IGN);
 424
 425         return service->fn();
 426 }
 427
 428 static void copy_to_log(int fd)
 429 {
 430         struct strbuf line = STRBUF_INIT;
 431         FILE *fp;
 432
 433         fp = fdopen(fd, "r");
 434         if (fp == NULL) {
 435                 logerror("fdopen of error channel failed");
 436                 close(fd);
 437                 return;
 438         }
 439
 440         while (strbuf_getline_lf(&line, fp) != EOF) {
 441                 logerror("%s", line.buf);
 442                 strbuf_setlen(&line, 0);
 443         }
 444
 445         strbuf_release(&line);
 446         fclose(fp);
 447 }
 448
 449 static int run_service_command(struct child_process *cld)
 450 {
 451         argv_array_push(&cld->args, ".");
 452         cld->git_cmd = 1;
 453         cld->err = -1;
 454         if (start_command(cld))
 455                 return -1;
 456
 457         close(0);
 458         close(1);
 459
 460         copy_to_log(cld->err);
 461
 462         return finish_command(cld);
 463 }
 464
 465 static int upload_pack(void)
 466 {
 467         struct child_process cld = CHILD_PROCESS_INIT;
 468         argv_array_pushl(&cld.args, "upload-pack", "--strict", NULL);
 469         argv_array_pushf(&cld.args, "--timeout=%u", timeout);
 470         return run_service_command(&cld);
 471 }
 472
 473 static int upload_archive(void)
 474 {
 475         struct child_process cld = CHILD_PROCESS_INIT;
 476         argv_array_push(&cld.args, "upload-archive");
 477         return run_service_command(&cld);
 478 }
 479
 480 static int receive_pack(void)
 481 {
 482         struct child_process cld = CHILD_PROCESS_INIT;
 483         argv_array_push(&cld.args, "receive-pack");
 484         return run_service_command(&cld);
 485 }
 486
 487 static struct daemon_service daemon_service[] = {
 488         { "upload-archive", "uploadarch", upload_archive, 0, 1 },
 489         { "upload-pack", "uploadpack", upload_pack, 1, 1 },
 490         { "receive-pack", "receivepack", receive_pack, 0, 1 },
 491 };
 492
 493 static void enable_service(const char *name, int ena)
 494 {
 495         int i;
 496         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 497                 if (!strcmp(daemon_service[i].name, name)) {
 498                         daemon_service[i].enabled = ena;
 499                         return;
 500                 }
 501         }
 502         die("No such service %s", name);
 503 }
 504
 505 static void make_service_overridable(const char *name, int ena)
 506 {
 507         int i;
 508         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 509                 if (!strcmp(daemon_service[i].name, name)) {
 510                         daemon_service[i].overridable = ena;
 511                         return;
 512                 }
 513         }
 514         die("No such service %s", name);
 515 }
 516
 517 static void parse_host_and_port(char *hostport, char **host,
 518         char **port)
 519 {
 520         if (*hostport == '[') {
 521                 char *end;
 522
 523                 end = strchr(hostport, ']');
 524                 if (!end)
 525                         die("Invalid request ('[' without ']')");
 526                 *end = '\0';
 527                 *host = hostport + 1;
 528                 if (!end[1])
 529                         *port = NULL;
 530                 else if (end[1] == ':')
 531                         *port = end + 2;
 532                 else
 533                         die("Garbage after end of host part");
 534         } else {
 535                 *host = hostport;
 536                 *port = strrchr(hostport, ':');
 537                 if (*port) {
 538                         **port = '\0';
 539                         ++*port;
 540                 }
 541         }
 542 }
 543
 544 /*
 545  * Sanitize a string from the client so that it's OK to be inserted into a
 546  * filesystem path. Specifically, we disallow slashes, runs of "..", and
 547  * trailing and leading dots, which means that the client cannot escape
 548  * our base path via ".." traversal.
 549  */
 550 static void sanitize_client(struct strbuf *out, const char *in)
 551 {
 552         for (; *in; in++) {
 553                 if (*in == '/')
 554                         continue;
 555                 if (*in == '.' && (!out->len || out->buf[out->len - 1] == '.'))
 556                         continue;
 557                 strbuf_addch(out, *in);
 558         }
 559
 560         while (out->len && out->buf[out->len - 1] == '.')
 561                 strbuf_setlen(out, out->len - 1);
 562 }
 563
 564 /*
 565  * Like sanitize_client, but we also perform any canonicalization
 566  * to make life easier on the admin.
 567  */
 568 static void canonicalize_client(struct strbuf *out, const char *in)
 569 {
 570         sanitize_client(out, in);
 571         strbuf_tolower(out);
 572 }
 573
 574 /*
 575  * Read the host as supplied by the client connection.
 576  */
 577 static void parse_host_arg(struct hostinfo *hi, char *extra_args, int buflen)
 578 {
 579         char *val;
 580         int vallen;
 581         char *end = extra_args + buflen;
 582
 583         if (extra_args < end && *extra_args) {
 584                 hi->saw_extended_args = 1;
 585                 if (strncasecmp("host=", extra_args, 5) == 0) {
 586                         val = extra_args + 5;
 587                         vallen = strlen(val) + 1;
 588                         if (*val) {
 589                                 /* Split <host>:<port> at colon. */
 590                                 char *host;
 591                                 char *port;
 592                                 parse_host_and_port(val, &host, &port);
 593                                 if (port)
 594                                         sanitize_client(&hi->tcp_port, port);
 595                                 canonicalize_client(&hi->hostname, host);
 596                                 hi->hostname_lookup_done = 0;
 597                         }
 598
 599                         /* On to the next one */
 600                         extra_args = val + vallen;
 601                 }
 602                 if (extra_args < end && *extra_args)
 603                         die("Invalid request");
 604         }
 605 }
 606
 607 /*
 608  * Locate canonical hostname and its IP address.
 609  */
 610 static void lookup_hostname(struct hostinfo *hi)
 611 {
 612         if (!hi->hostname_lookup_done && hi->hostname.len) {
 613 #ifndef NO_IPV6
 614                 struct addrinfo hints;
 615                 struct addrinfo *ai;
 616                 int gai;
 617                 static char addrbuf[HOST_NAME_MAX + 1];
 618
 619                 memset(&hints, 0, sizeof(hints));
 620                 hints.ai_flags = AI_CANONNAME;
 621
 622                 gai = getaddrinfo(hi->hostname.buf, NULL, &hints, &ai);
 623                 if (!gai) {
 624                         struct sockaddr_in *sin_addr = (void *)ai->ai_addr;
 625
 626                         inet_ntop(AF_INET, &sin_addr->sin_addr,
 627                                   addrbuf, sizeof(addrbuf));
 628                         strbuf_addstr(&hi->ip_address, addrbuf);
 629
 630                         if (ai->ai_canonname)
 631                                 sanitize_client(&hi->canon_hostname,
 632                                                 ai->ai_canonname);
 633                         else
 634                                 strbuf_addbuf(&hi->canon_hostname,
 635                                               &hi->ip_address);
 636
 637                         freeaddrinfo(ai);
 638                 }
 639 #else
 640                 struct hostent *hent;
 641                 struct sockaddr_in sa;
 642                 char **ap;
 643                 static char addrbuf[HOST_NAME_MAX + 1];
 644
 645                 hent = gethostbyname(hi->hostname.buf);
 646                 if (hent) {
 647                         ap = hent->h_addr_list;
 648                         memset(&sa, 0, sizeof sa);
 649                         sa.sin_family = hent->h_addrtype;
 650                         sa.sin_port = htons(0);
 651                         memcpy(&sa.sin_addr, *ap, hent->h_length);
 652
 653                         inet_ntop(hent->h_addrtype, &sa.sin_addr,
 654                                   addrbuf, sizeof(addrbuf));
 655
 656                         sanitize_client(&hi->canon_hostname, hent->h_name);
 657                         strbuf_addstr(&hi->ip_address, addrbuf);
 658                 }
 659 #endif
 660                 hi->hostname_lookup_done = 1;
 661         }
 662 }
 663
 664 static void hostinfo_init(struct hostinfo *hi)
 665 {
 666         memset(hi, 0, sizeof(*hi));
 667         strbuf_init(&hi->hostname, 0);
 668         strbuf_init(&hi->canon_hostname, 0);
 669         strbuf_init(&hi->ip_address, 0);
 670         strbuf_init(&hi->tcp_port, 0);
 671 }
 672
 673 static void hostinfo_clear(struct hostinfo *hi)
 674 {
 675         strbuf_release(&hi->hostname);
 676         strbuf_release(&hi->canon_hostname);
 677         strbuf_release(&hi->ip_address);
 678         strbuf_release(&hi->tcp_port);
 679 }
 680
 681 static void set_keep_alive(int sockfd)
 682 {
 683         int ka = 1;
 684
 685         if (setsockopt(sockfd, SOL_SOCKET, SO_KEEPALIVE, &ka, sizeof(ka)) < 0) {
 686                 if (errno != ENOTSOCK)
 687                         logerror("unable to set SO_KEEPALIVE on socket: %s",
 688                                 strerror(errno));
 689         }
 690 }
 691
 692 static int execute(void)
 693 {
 694         char *line = packet_buffer;
 695         int pktlen, len, i;
 696         char *addr = getenv("REMOTE_ADDR"), *port = getenv("REMOTE_PORT");
 697         struct hostinfo hi;
 698
 699         hostinfo_init(&hi);
 700
 701         if (addr)
 702                 loginfo("Connection from %s:%s", addr, port);
 703
 704         set_keep_alive(0);
 705         alarm(init_timeout ? init_timeout : timeout);
 706         pktlen = packet_read(0, NULL, NULL, packet_buffer, sizeof(packet_buffer), 0);
 707         alarm(0);
 708
 709         len = strlen(line);
 710         if (pktlen != len)
 711                 loginfo("Extended attributes (%d bytes) exist <%.*s>",
 712                         (int) pktlen - len,
 713                         (int) pktlen - len, line + len + 1);
 714         if (len && line[len-1] == '\n') {
 715                 line[--len] = 0;
 716                 pktlen--;
 717         }
 718
 719         if (len != pktlen)
 720                 parse_host_arg(&hi, line + len + 1, pktlen - len - 1);
 721
 722         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 723                 struct daemon_service *s = &(daemon_service[i]);
 724                 const char *arg;
 725
 726                 if (skip_prefix(line, "git-", &arg) &&
 727                     skip_prefix(arg, s->name, &arg) &&
 728                     *arg++ == ' ') {
 729                         /*
 730                          * Note: The directory here is probably context sensitive,
 731                          * and might depend on the actual service being performed.
 732                          */
 733                         int rc = run_service(arg, s, &hi);
 734                         hostinfo_clear(&hi);
 735                         return rc;
 736                 }
 737         }
 738
 739         hostinfo_clear(&hi);
 740         logerror("Protocol error: '%s'", line);
 741         return -1;
 742 }
 743
 744 static int addrcmp(const struct sockaddr_storage *s1,
 745     const struct sockaddr_storage *s2)
 746 {
 747         const struct sockaddr *sa1 = (const struct sockaddr*) s1;
 748         const struct sockaddr *sa2 = (const struct sockaddr*) s2;
 749
 750         if (sa1->sa_family != sa2->sa_family)
 751                 return sa1->sa_family - sa2->sa_family;
 752         if (sa1->sa_family == AF_INET)
 753                 return memcmp(&((struct sockaddr_in *)s1)->sin_addr,
 754                     &((struct sockaddr_in *)s2)->sin_addr,
 755                     sizeof(struct in_addr));
 756 #ifndef NO_IPV6
 757         if (sa1->sa_family == AF_INET6)
 758                 return memcmp(&((struct sockaddr_in6 *)s1)->sin6_addr,
 759                     &((struct sockaddr_in6 *)s2)->sin6_addr,
 760                     sizeof(struct in6_addr));
 761 #endif
 762         return 0;
 763 }
 764
 765 static int max_connections = 32;
 766
 767 static unsigned int live_children;
 768
 769 static struct child {
 770         struct child *next;
 771         struct child_process cld;
 772         struct sockaddr_storage address;
 773 } *firstborn;
 774
 775 static void add_child(struct child_process *cld, struct sockaddr *addr, socklen_t addrlen)
 776 {
 777         struct child *newborn, **cradle;
 778
 779         newborn = xcalloc(1, sizeof(*newborn));
 780         live_children++;
 781         memcpy(&newborn->cld, cld, sizeof(*cld));
 782         memcpy(&newborn->address, addr, addrlen);
 783         for (cradle = &firstborn; *cradle; cradle = &(*cradle)->next)
 784                 if (!addrcmp(&(*cradle)->address, &newborn->address))
 785                         break;
 786         newborn->next = *cradle;
 787         *cradle = newborn;
 788 }
 789
 790 /*
 791  * This gets called if the number of connections grows
 792  * past "max_connections".
 793  *
 794  * We kill the newest connection from a duplicate IP.
 795  */
 796 static void kill_some_child(void)
 797 {
 798         const struct child *blanket, *next;
 799
 800         if (!(blanket = firstborn))
 801                 return;
 802
 803         for (; (next = blanket->next); blanket = next)
 804                 if (!addrcmp(&blanket->address, &next->address)) {
 805                         kill(blanket->cld.pid, SIGTERM);
 806                         break;
 807                 }
 808 }
 809
 810 static void check_dead_children(void)
 811 {
 812         int status;
 813         pid_t pid;
 814
 815         struct child **cradle, *blanket;
 816         for (cradle = &firstborn; (blanket = *cradle);)
 817                 if ((pid = waitpid(blanket->cld.pid, &status, WNOHANG)) > 1) {
 818                         const char *dead = "";
 819                         if (status)
 820                                 dead = " (with error)";
 821                         loginfo("[%"PRIuMAX"] Disconnected%s", (uintmax_t)pid, dead);
 822
 823                         /* remove the child */
 824                         *cradle = blanket->next;
 825                         live_children--;
 826                         child_process_clear(&blanket->cld);
 827                         free(blanket);
 828                 } else
 829                         cradle = &blanket->next;
 830 }
 831
 832 static struct argv_array cld_argv = ARGV_ARRAY_INIT;
 833 static void handle(int incoming, struct sockaddr *addr, socklen_t addrlen)
 834 {
 835         struct child_process cld = CHILD_PROCESS_INIT;
 836
 837         if (max_connections && live_children >= max_connections) {
 838                 kill_some_child();
 839                 sleep(1);  /* give it some time to die */
 840                 check_dead_children();
 841                 if (live_children >= max_connections) {
 842                         close(incoming);
 843                         logerror("Too many children, dropping connection");
 844                         return;
 845                 }
 846         }
 847
 848         if (addr->sa_family == AF_INET) {
 849                 char buf[128] = "";
 850                 struct sockaddr_in *sin_addr = (void *) addr;
 851                 inet_ntop(addr->sa_family, &sin_addr->sin_addr, buf, sizeof(buf));
 852                 argv_array_pushf(&cld.env_array, "REMOTE_ADDR=%s", buf);
 853                 argv_array_pushf(&cld.env_array, "REMOTE_PORT=%d",
 854                                  ntohs(sin_addr->sin_port));
 855 #ifndef NO_IPV6
 856         } else if (addr->sa_family == AF_INET6) {
 857                 char buf[128] = "";
 858                 struct sockaddr_in6 *sin6_addr = (void *) addr;
 859                 inet_ntop(AF_INET6, &sin6_addr->sin6_addr, buf, sizeof(buf));
 860                 argv_array_pushf(&cld.env_array, "REMOTE_ADDR=[%s]", buf);
 861                 argv_array_pushf(&cld.env_array, "REMOTE_PORT=%d",
 862                                  ntohs(sin6_addr->sin6_port));
 863 #endif
 864         }
 865
 866         cld.argv = cld_argv.argv;
 867         cld.in = incoming;
 868         cld.out = dup(incoming);
 869
 870         if (start_command(&cld))
 871                 logerror("unable to fork");
 872         else
 873                 add_child(&cld, addr, addrlen);
 874 }
 875
 876 static void child_handler(int signo)
 877 {
 878         /*
 879          * Otherwise empty handler because systemcalls will get interrupted
 880          * upon signal receipt
 881          * SysV needs the handler to be rearmed
 882          */
 883         signal(SIGCHLD, child_handler);
 884 }
 885
 886 static int set_reuse_addr(int sockfd)
 887 {
 888         int on = 1;
 889
 890         if (!reuseaddr)
 891                 return 0;
 892         return setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
 893                           &on, sizeof(on));
 894 }
 895
 896 struct socketlist {
 897         int *list;
 898         size_t nr;
 899         size_t alloc;
 900 };
 901
 902 static const char *ip2str(int family, struct sockaddr *sin, socklen_t len)
 903 {
 904 #ifdef NO_IPV6
 905         static char ip[INET_ADDRSTRLEN];
 906 #else
 907         static char ip[INET6_ADDRSTRLEN];
 908 #endif
 909
 910         switch (family) {
 911 #ifndef NO_IPV6
 912         case AF_INET6:
 913                 inet_ntop(family, &((struct sockaddr_in6*)sin)->sin6_addr, ip, len);
 914                 break;
 915 #endif
 916         case AF_INET:
 917                 inet_ntop(family, &((struct sockaddr_in*)sin)->sin_addr, ip, len);
 918                 break;
 919         default:
 920                 xsnprintf(ip, sizeof(ip), "<unknown>");
 921         }
 922         return ip;
 923 }
 924
 925 #ifndef NO_IPV6
 926
 927 static int setup_named_sock(char *listen_addr, int listen_port, struct socketlist *socklist)
 928 {
 929         int socknum = 0;
 930         char pbuf[NI_MAXSERV];
 931         struct addrinfo hints, *ai0, *ai;
 932         int gai;
 933         long flags;
 934
 935         xsnprintf(pbuf, sizeof(pbuf), "%d", listen_port);
 936         memset(&hints, 0, sizeof(hints));
 937         hints.ai_family = AF_UNSPEC;
 938         hints.ai_socktype = SOCK_STREAM;
 939         hints.ai_protocol = IPPROTO_TCP;
 940         hints.ai_flags = AI_PASSIVE;
 941
 942         gai = getaddrinfo(listen_addr, pbuf, &hints, &ai0);
 943         if (gai) {
 944                 logerror("getaddrinfo() for %s failed: %s", listen_addr, gai_strerror(gai));
 945                 return 0;
 946         }
 947
 948         for (ai = ai0; ai; ai = ai->ai_next) {
 949                 int sockfd;
 950
 951                 sockfd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
 952                 if (sockfd < 0)
 953                         continue;
 954                 if (sockfd >= FD_SETSIZE) {
 955                         logerror("Socket descriptor too large");
 956                         close(sockfd);
 957                         continue;
 958                 }
 959
 960 #ifdef IPV6_V6ONLY
 961                 if (ai->ai_family == AF_INET6) {
 962                         int on = 1;
 963                         setsockopt(sockfd, IPPROTO_IPV6, IPV6_V6ONLY,
 964                                    &on, sizeof(on));
 965                         /* Note: error is not fatal */
 966                 }
 967 #endif
 968
 969                 if (set_reuse_addr(sockfd)) {
 970                         logerror("Could not set SO_REUSEADDR: %s", strerror(errno));
 971                         close(sockfd);
 972                         continue;
 973                 }
 974
 975                 set_keep_alive(sockfd);
 976
 977                 if (bind(sockfd, ai->ai_addr, ai->ai_addrlen) < 0) {
 978                         logerror("Could not bind to %s: %s",
 979                                  ip2str(ai->ai_family, ai->ai_addr, ai->ai_addrlen),
 980                                  strerror(errno));
 981                         close(sockfd);
 982                         continue;       /* not fatal */
 983                 }
 984                 if (listen(sockfd, 5) < 0) {
 985                         logerror("Could not listen 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
 992                 flags = fcntl(sockfd, F_GETFD, 0);
 993                 if (flags >= 0)
 994                         fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
 995
 996                 ALLOC_GROW(socklist->list, socklist->nr + 1, socklist->alloc);
 997                 socklist->list[socklist->nr++] = sockfd;
 998                 socknum++;
 999         }
1000
1001         freeaddrinfo(ai0);
1002
1003         return socknum;
1004 }
1005
1006 #else /* NO_IPV6 */
1007
1008 static int setup_named_sock(char *listen_addr, int listen_port, struct socketlist *socklist)
1009 {
1010         struct sockaddr_in sin;
1011         int sockfd;
1012         long flags;
1013
1014         memset(&sin, 0, sizeof sin);
1015         sin.sin_family = AF_INET;
1016         sin.sin_port = htons(listen_port);
1017
1018         if (listen_addr) {
1019                 /* Well, host better be an IP address here. */
1020                 if (inet_pton(AF_INET, listen_addr, &sin.sin_addr.s_addr) <= 0)
1021                         return 0;
1022         } else {
1023                 sin.sin_addr.s_addr = htonl(INADDR_ANY);
1024         }
1025
1026         sockfd = socket(AF_INET, SOCK_STREAM, 0);
1027         if (sockfd < 0)
1028                 return 0;
1029
1030         if (set_reuse_addr(sockfd)) {
1031                 logerror("Could not set SO_REUSEADDR: %s", strerror(errno));
1032                 close(sockfd);
1033                 return 0;
1034         }
1035
1036         set_keep_alive(sockfd);
1037
1038         if ( bind(sockfd, (struct sockaddr *)&sin, sizeof sin) < 0 ) {
1039                 logerror("Could not bind to %s: %s",
1040                          ip2str(AF_INET, (struct sockaddr *)&sin, sizeof(sin)),
1041                          strerror(errno));
1042                 close(sockfd);
1043                 return 0;
1044         }
1045
1046         if (listen(sockfd, 5) < 0) {
1047                 logerror("Could not listen to %s: %s",
1048                          ip2str(AF_INET, (struct sockaddr *)&sin, sizeof(sin)),
1049                          strerror(errno));
1050                 close(sockfd);
1051                 return 0;
1052         }
1053
1054         flags = fcntl(sockfd, F_GETFD, 0);
1055         if (flags >= 0)
1056                 fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
1057
1058         ALLOC_GROW(socklist->list, socklist->nr + 1, socklist->alloc);
1059         socklist->list[socklist->nr++] = sockfd;
1060         return 1;
1061 }
1062
1063 #endif
1064
1065 static void socksetup(struct string_list *listen_addr, int listen_port, struct socketlist *socklist)
1066 {
1067         if (!listen_addr->nr)
1068                 setup_named_sock(NULL, listen_port, socklist);
1069         else {
1070                 int i, socknum;
1071                 for (i = 0; i < listen_addr->nr; i++) {
1072                         socknum = setup_named_sock(listen_addr->items[i].string,
1073                                                    listen_port, socklist);
1074
1075                         if (socknum == 0)
1076                                 logerror("unable to allocate any listen sockets for host %s on port %u",
1077                                          listen_addr->items[i].string, listen_port);
1078                 }
1079         }
1080 }
1081
1082 static int service_loop(struct socketlist *socklist)
1083 {
1084         struct pollfd *pfd;
1085         int i;
1086
1087         pfd = xcalloc(socklist->nr, sizeof(struct pollfd));
1088
1089         for (i = 0; i < socklist->nr; i++) {
1090                 pfd[i].fd = socklist->list[i];
1091                 pfd[i].events = POLLIN;
1092         }
1093
1094         signal(SIGCHLD, child_handler);
1095
1096         for (;;) {
1097                 int i;
1098
1099                 check_dead_children();
1100
1101                 if (poll(pfd, socklist->nr, -1) < 0) {
1102                         if (errno != EINTR) {
1103                                 logerror("Poll failed, resuming: %s",
1104                                       strerror(errno));
1105                                 sleep(1);
1106                         }
1107                         continue;
1108                 }
1109
1110                 for (i = 0; i < socklist->nr; i++) {
1111                         if (pfd[i].revents & POLLIN) {
1112                                 union {
1113                                         struct sockaddr sa;
1114                                         struct sockaddr_in sai;
1115 #ifndef NO_IPV6
1116                                         struct sockaddr_in6 sai6;
1117 #endif
1118                                 } ss;
1119                                 socklen_t sslen = sizeof(ss);
1120                                 int incoming = accept(pfd[i].fd, &ss.sa, &sslen);
1121                                 if (incoming < 0) {
1122                                         switch (errno) {
1123                                         case EAGAIN:
1124                                         case EINTR:
1125                                         case ECONNABORTED:
1126                                                 continue;
1127                                         default:
1128                                                 die_errno("accept returned");
1129                                         }
1130                                 }
1131                                 handle(incoming, &ss.sa, sslen);
1132                         }
1133                 }
1134         }
1135 }
1136
1137 #ifdef NO_POSIX_GOODIES
1138
1139 struct credentials;
1140
1141 static void drop_privileges(struct credentials *cred)
1142 {
1143         /* nothing */
1144 }
1145
1146 static struct credentials *prepare_credentials(const char *user_name,
1147     const char *group_name)
1148 {
1149         die("--user not supported on this platform");
1150 }
1151
1152 #else
1153
1154 struct credentials {
1155         struct passwd *pass;
1156         gid_t gid;
1157 };
1158
1159 static void drop_privileges(struct credentials *cred)
1160 {
1161         if (cred && (initgroups(cred->pass->pw_name, cred->gid) ||
1162             setgid (cred->gid) || setuid(cred->pass->pw_uid)))
1163                 die("cannot drop privileges");
1164 }
1165
1166 static struct credentials *prepare_credentials(const char *user_name,
1167     const char *group_name)
1168 {
1169         static struct credentials c;
1170
1171         c.pass = getpwnam(user_name);
1172         if (!c.pass)
1173                 die("user not found - %s", user_name);
1174
1175         if (!group_name)
1176                 c.gid = c.pass->pw_gid;
1177         else {
1178                 struct group *group = getgrnam(group_name);
1179                 if (!group)
1180                         die("group not found - %s", group_name);
1181
1182                 c.gid = group->gr_gid;
1183         }
1184
1185         return &c;
1186 }
1187 #endif
1188
1189 static int serve(struct string_list *listen_addr, int listen_port,
1190     struct credentials *cred)
1191 {
1192         struct socketlist socklist = { NULL, 0, 0 };
1193
1194         socksetup(listen_addr, listen_port, &socklist);
1195         if (socklist.nr == 0)
1196                 die("unable to allocate any listen sockets on port %u",
1197                     listen_port);
1198
1199         drop_privileges(cred);
1200
1201         loginfo("Ready to rumble");
1202
1203         return service_loop(&socklist);
1204 }
1205
1206 int cmd_main(int argc, const char **argv)
1207 {
1208         int listen_port = 0;
1209         struct string_list listen_addr = STRING_LIST_INIT_NODUP;
1210         int serve_mode = 0, inetd_mode = 0;
1211         const char *pid_file = NULL, *user_name = NULL, *group_name = NULL;
1212         int detach = 0;
1213         struct credentials *cred = NULL;
1214         int i;
1215
1216         for (i = 1; i < argc; i++) {
1217                 const char *arg = argv[i];
1218                 const char *v;
1219
1220                 if (skip_prefix(arg, "--listen=", &v)) {
1221                         string_list_append(&listen_addr, xstrdup_tolower(v));
1222                         continue;
1223                 }
1224                 if (skip_prefix(arg, "--port=", &v)) {
1225                         char *end;
1226                         unsigned long n;
1227                         n = strtoul(v, &end, 0);
1228                         if (*v && !*end) {
1229                                 listen_port = n;
1230                                 continue;
1231                         }
1232                 }
1233                 if (!strcmp(arg, "--serve")) {
1234                         serve_mode = 1;
1235                         continue;
1236                 }
1237                 if (!strcmp(arg, "--inetd")) {
1238                         inetd_mode = 1;
1239                         log_syslog = 1;
1240                         continue;
1241                 }
1242                 if (!strcmp(arg, "--verbose")) {
1243                         verbose = 1;
1244                         continue;
1245                 }
1246                 if (!strcmp(arg, "--syslog")) {
1247                         log_syslog = 1;
1248                         continue;
1249                 }
1250                 if (!strcmp(arg, "--export-all")) {
1251                         export_all_trees = 1;
1252                         continue;
1253                 }
1254                 if (skip_prefix(arg, "--access-hook=", &v)) {
1255                         access_hook = v;
1256                         continue;
1257                 }
1258                 if (skip_prefix(arg, "--timeout=", &v)) {
1259                         timeout = atoi(v);
1260                         continue;
1261                 }
1262                 if (skip_prefix(arg, "--init-timeout=", &v)) {
1263                         init_timeout = atoi(v);
1264                         continue;
1265                 }
1266                 if (skip_prefix(arg, "--max-connections=", &v)) {
1267                         max_connections = atoi(v);
1268                         if (max_connections < 0)
1269                                 max_connections = 0;            /* unlimited */
1270                         continue;
1271                 }
1272                 if (!strcmp(arg, "--strict-paths")) {
1273                         strict_paths = 1;
1274                         continue;
1275                 }
1276                 if (skip_prefix(arg, "--base-path=", &v)) {
1277                         base_path = v;
1278                         continue;
1279                 }
1280                 if (!strcmp(arg, "--base-path-relaxed")) {
1281                         base_path_relaxed = 1;
1282                         continue;
1283                 }
1284                 if (skip_prefix(arg, "--interpolated-path=", &v)) {
1285                         interpolated_path = v;
1286                         continue;
1287                 }
1288                 if (!strcmp(arg, "--reuseaddr")) {
1289                         reuseaddr = 1;
1290                         continue;
1291                 }
1292                 if (!strcmp(arg, "--user-path")) {
1293                         user_path = "";
1294                         continue;
1295                 }
1296                 if (skip_prefix(arg, "--user-path=", &v)) {
1297                         user_path = v;
1298                         continue;
1299                 }
1300                 if (skip_prefix(arg, "--pid-file=", &v)) {
1301                         pid_file = v;
1302                         continue;
1303                 }
1304                 if (!strcmp(arg, "--detach")) {
1305                         detach = 1;
1306                         log_syslog = 1;
1307                         continue;
1308                 }
1309                 if (skip_prefix(arg, "--user=", &v)) {
1310                         user_name = v;
1311                         continue;
1312                 }
1313                 if (skip_prefix(arg, "--group=", &v)) {
1314                         group_name = v;
1315                         continue;
1316                 }
1317                 if (skip_prefix(arg, "--enable=", &v)) {
1318                         enable_service(v, 1);
1319                         continue;
1320                 }
1321                 if (skip_prefix(arg, "--disable=", &v)) {
1322                         enable_service(v, 0);
1323                         continue;
1324                 }
1325                 if (skip_prefix(arg, "--allow-override=", &v)) {
1326                         make_service_overridable(v, 1);
1327                         continue;
1328                 }
1329                 if (skip_prefix(arg, "--forbid-override=", &v)) {
1330                         make_service_overridable(v, 0);
1331                         continue;
1332                 }
1333                 if (!strcmp(arg, "--informative-errors")) {
1334                         informative_errors = 1;
1335                         continue;
1336                 }
1337                 if (!strcmp(arg, "--no-informative-errors")) {
1338                         informative_errors = 0;
1339                         continue;
1340                 }
1341                 if (!strcmp(arg, "--")) {
1342                         ok_paths = &argv[i+1];
1343                         break;
1344                 } else if (arg[0] != '-') {
1345                         ok_paths = &argv[i];
1346                         break;
1347                 }
1348
1349                 usage(daemon_usage);
1350         }
1351
1352         if (log_syslog) {
1353                 openlog("git-daemon", LOG_PID, LOG_DAEMON);
1354                 set_die_routine(daemon_die);
1355         } else
1356                 /* avoid splitting a message in the middle */
1357                 setvbuf(stderr, NULL, _IOFBF, 4096);
1358
1359         if (inetd_mode && (detach || group_name || user_name))
1360                 die("--detach, --user and --group are incompatible with --inetd");
1361
1362         if (inetd_mode && (listen_port || (listen_addr.nr > 0)))
1363                 die("--listen= and --port= are incompatible with --inetd");
1364         else if (listen_port == 0)
1365                 listen_port = DEFAULT_GIT_PORT;
1366
1367         if (group_name && !user_name)
1368                 die("--group supplied without --user");
1369
1370         if (user_name)
1371                 cred = prepare_credentials(user_name, group_name);
1372
1373         if (strict_paths && (!ok_paths || !*ok_paths))
1374                 die("option --strict-paths requires a whitelist");
1375
1376         if (base_path && !is_directory(base_path))
1377                 die("base-path '%s' does not exist or is not a directory",
1378                     base_path);
1379
1380         if (inetd_mode) {
1381                 if (!freopen("/dev/null", "w", stderr))
1382                         die_errno("failed to redirect stderr to /dev/null");
1383         }
1384
1385         if (inetd_mode || serve_mode)
1386                 return execute();
1387
1388         if (detach) {
1389                 if (daemonize())
1390                         die("--detach not supported on this platform");
1391         }
1392
1393         if (pid_file)
1394                 write_file(pid_file, "%"PRIuMAX, (uintmax_t) getpid());
1395
1396         /* prepare argv for serving-processes */
1397         argv_array_push(&cld_argv, argv[0]); /* git-daemon */
1398         argv_array_push(&cld_argv, "--serve");
1399         for (i = 1; i < argc; ++i)
1400                 argv_array_push(&cld_argv, argv[i]);
1401
1402         return serve(&listen_addr, listen_port, cred);
1403 }