daemon.c

   1 #include "cache.h"
   2 #include "pkt-line.h"
   3 #include "exec_cmd.h"
   4 #include "run-command.h"
   5 #include "strbuf.h"
   6 #include "string-list.h"
   7
   8 #ifndef HOST_NAME_MAX
   9 #define HOST_NAME_MAX 256
  10 #endif
  11
  12 #ifdef NO_INITGROUPS
  13 #define initgroups(x, y) (0) /* nothing */
  14 #endif
  15
  16 static int log_syslog;
  17 static int verbose;
  18 static int reuseaddr;
  19 static int informative_errors;
  20
  21 static const char daemon_usage[] =
  22 "git daemon [--verbose] [--syslog] [--export-all]\n"
  23 "           [--timeout=<n>] [--init-timeout=<n>] [--max-connections=<n>]\n"
  24 "           [--strict-paths] [--base-path=<path>] [--base-path-relaxed]\n"
  25 "           [--user-path | --user-path=<path>]\n"
  26 "           [--interpolated-path=<path>]\n"
  27 "           [--reuseaddr] [--pid-file=<file>]\n"
  28 "           [--(enable|disable|allow-override|forbid-override)=<service>]\n"
  29 "           [--access-hook=<path>]\n"
  30 "           [--inetd | [--listen=<host_or_ipaddr>] [--port=<n>]\n"
  31 "                      [--detach] [--user=<user> [--group=<group>]]\n"
  32 "           [<directory>...]";
  33
  34 /* List of acceptable pathname prefixes */
  35 static char **ok_paths;
  36 static int strict_paths;
  37
  38 /* If this is set, git-daemon-export-ok is not required */
  39 static int export_all_trees;
  40
  41 /* Take all paths relative to this one if non-NULL */
  42 static const char *base_path;
  43 static const char *interpolated_path;
  44 static int base_path_relaxed;
  45
  46 /* Flag indicating client sent extra args. */
  47 static int saw_extended_args;
  48
  49 /* If defined, ~user notation is allowed and the string is inserted
  50  * after ~user/.  E.g. a request to git://host/~alice/frotz would
  51  * go to /home/alice/pub_git/frotz with --user-path=pub_git.
  52  */
  53 static const char *user_path;
  54
  55 /* Timeout, and initial timeout */
  56 static unsigned int timeout;
  57 static unsigned int init_timeout;
  58
  59 static char *hostname;
  60 static char *canon_hostname;
  61 static char *ip_address;
  62 static char *tcp_port;
  63
  64 static int hostname_lookup_done;
  65
  66 static void lookup_hostname(void);
  67
  68 static const char *get_canon_hostname(void)
  69 {
  70         lookup_hostname();
  71         return canon_hostname;
  72 }
  73
  74 static const char *get_ip_address(void)
  75 {
  76         lookup_hostname();
  77         return ip_address;
  78 }
  79
  80 static void logreport(int priority, const char *err, va_list params)
  81 {
  82         if (log_syslog) {
  83                 char buf[1024];
  84                 vsnprintf(buf, sizeof(buf), err, params);
  85                 syslog(priority, "%s", buf);
  86         } else {
  87                 /*
  88                  * Since stderr is set to buffered mode, the
  89                  * logging of different processes will not overlap
  90                  * unless they overflow the (rather big) buffers.
  91                  */
  92                 fprintf(stderr, "[%"PRIuMAX"] ", (uintmax_t)getpid());
  93                 vfprintf(stderr, err, params);
  94                 fputc('\n', stderr);
  95                 fflush(stderr);
  96         }
  97 }
  98
  99 __attribute__((format (printf, 1, 2)))
 100 static void logerror(const char *err, ...)
 101 {
 102         va_list params;
 103         va_start(params, err);
 104         logreport(LOG_ERR, err, params);
 105         va_end(params);
 106 }
 107
 108 __attribute__((format (printf, 1, 2)))
 109 static void loginfo(const char *err, ...)
 110 {
 111         va_list params;
 112         if (!verbose)
 113                 return;
 114         va_start(params, err);
 115         logreport(LOG_INFO, err, params);
 116         va_end(params);
 117 }
 118
 119 static void NORETURN daemon_die(const char *err, va_list params)
 120 {
 121         logreport(LOG_ERR, err, params);
 122         exit(1);
 123 }
 124
 125 static void strbuf_addstr_or_null(struct strbuf *sb, const char *s)
 126 {
 127         if (s)
 128                 strbuf_addstr(sb, s);
 129 }
 130
 131 struct expand_path_context {
 132         const char *directory;
 133 };
 134
 135 static size_t expand_path(struct strbuf *sb, const char *placeholder, void *ctx)
 136 {
 137         struct expand_path_context *context = ctx;
 138
 139         switch (placeholder[0]) {
 140         case 'H':
 141                 strbuf_addstr_or_null(sb, hostname);
 142                 return 1;
 143         case 'C':
 144                 if (placeholder[1] == 'H') {
 145                         strbuf_addstr_or_null(sb, get_canon_hostname());
 146                         return 2;
 147                 }
 148                 break;
 149         case 'I':
 150                 if (placeholder[1] == 'P') {
 151                         strbuf_addstr_or_null(sb, get_ip_address());
 152                         return 2;
 153                 }
 154                 break;
 155         case 'P':
 156                 strbuf_addstr_or_null(sb, tcp_port);
 157                 return 1;
 158         case 'D':
 159                 strbuf_addstr(sb, context->directory);
 160                 return 1;
 161         }
 162         return 0;
 163 }
 164
 165 static const char *path_ok(const char *directory)
 166 {
 167         static char rpath[PATH_MAX];
 168         static char interp_path[PATH_MAX];
 169         const char *path;
 170         const char *dir;
 171
 172         dir = directory;
 173
 174         if (daemon_avoid_alias(dir)) {
 175                 logerror("'%s': aliased", dir);
 176                 return NULL;
 177         }
 178
 179         if (*dir == '~') {
 180                 if (!user_path) {
 181                         logerror("'%s': User-path not allowed", dir);
 182                         return NULL;
 183                 }
 184                 if (*user_path) {
 185                         /* Got either "~alice" or "~alice/foo";
 186                          * rewrite them to "~alice/%s" or
 187                          * "~alice/%s/foo".
 188                          */
 189                         int namlen, restlen = strlen(dir);
 190                         const char *slash = strchr(dir, '/');
 191                         if (!slash)
 192                                 slash = dir + restlen;
 193                         namlen = slash - dir;
 194                         restlen -= namlen;
 195                         loginfo("userpath <%s>, request <%s>, namlen %d, restlen %d, slash <%s>", user_path, dir, namlen, restlen, slash);
 196                         snprintf(rpath, PATH_MAX, "%.*s/%s%.*s",
 197                                  namlen, dir, user_path, restlen, slash);
 198                         dir = rpath;
 199                 }
 200         }
 201         else if (interpolated_path && saw_extended_args) {
 202                 struct strbuf expanded_path = STRBUF_INIT;
 203                 struct expand_path_context context;
 204
 205                 context.directory = directory;
 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                 strlcpy(interp_path, expanded_path.buf, PATH_MAX);
 216                 strbuf_release(&expanded_path);
 217                 loginfo("Interpolated dir '%s'", interp_path);
 218
 219                 dir = interp_path;
 220         }
 221         else if (base_path) {
 222                 if (*dir != '/') {
 223                         /* Allow only absolute */
 224                         logerror("'%s': Non-absolute path denied (base-path active)", dir);
 225                         return NULL;
 226                 }
 227                 snprintf(rpath, PATH_MAX, "%s%s", base_path, dir);
 228                 dir = rpath;
 229         }
 230
 231         path = enter_repo(dir, strict_paths);
 232         if (!path && base_path && base_path_relaxed) {
 233                 /*
 234                  * if we fail and base_path_relaxed is enabled, try without
 235                  * prefixing the base path
 236                  */
 237                 dir = directory;
 238                 path = enter_repo(dir, strict_paths);
 239         }
 240
 241         if (!path) {
 242                 logerror("'%s' does not appear to be a git repository", dir);
 243                 return NULL;
 244         }
 245
 246         if ( ok_paths && *ok_paths ) {
 247                 char **pp;
 248                 int pathlen = strlen(path);
 249
 250                 /* The validation is done on the paths after enter_repo
 251                  * appends optional {.git,.git/.git} and friends, but
 252                  * it does not use getcwd().  So if your /pub is
 253                  * a symlink to /mnt/pub, you can whitelist /pub and
 254                  * do not have to say /mnt/pub.
 255                  * Do not say /pub/.
 256                  */
 257                 for ( pp = ok_paths ; *pp ; pp++ ) {
 258                         int len = strlen(*pp);
 259                         if (len <= pathlen &&
 260                             !memcmp(*pp, path, len) &&
 261                             (path[len] == '\0' ||
 262                              (!strict_paths && path[len] == '/')))
 263                                 return path;
 264                 }
 265         }
 266         else {
 267                 /* be backwards compatible */
 268                 if (!strict_paths)
 269                         return path;
 270         }
 271
 272         logerror("'%s': not in whitelist", path);
 273         return NULL;            /* Fallthrough. Deny by default */
 274 }
 275
 276 typedef int (*daemon_service_fn)(void);
 277 struct daemon_service {
 278         const char *name;
 279         const char *config_name;
 280         daemon_service_fn fn;
 281         int enabled;
 282         int overridable;
 283 };
 284
 285 static struct daemon_service *service_looking_at;
 286 static int service_enabled;
 287
 288 static int git_daemon_config(const char *var, const char *value, void *cb)
 289 {
 290         const char *service;
 291
 292         if (skip_prefix(var, "daemon.", &service) &&
 293             !strcmp(service, service_looking_at->config_name)) {
 294                 service_enabled = git_config_bool(var, value);
 295                 return 0;
 296         }
 297
 298         /* we are not interested in parsing any other configuration here */
 299         return 0;
 300 }
 301
 302 static int daemon_error(const char *dir, const char *msg)
 303 {
 304         if (!informative_errors)
 305                 msg = "access denied or repository not exported";
 306         packet_write(1, "ERR %s: %s", msg, dir);
 307         return -1;
 308 }
 309
 310 static const char *access_hook;
 311
 312 static int run_access_hook(struct daemon_service *service, const char *dir, const char *path)
 313 {
 314         struct child_process child;
 315         struct strbuf buf = STRBUF_INIT;
 316         const char *argv[8];
 317         const char **arg = argv;
 318         char *eol;
 319         int seen_errors = 0;
 320
 321 #define STRARG(x) ((x) ? (x) : "")
 322         *arg++ = access_hook;
 323         *arg++ = service->name;
 324         *arg++ = path;
 325         *arg++ = STRARG(hostname);
 326         *arg++ = STRARG(get_canon_hostname());
 327         *arg++ = STRARG(get_ip_address());
 328         *arg++ = STRARG(tcp_port);
 329         *arg = NULL;
 330 #undef STRARG
 331
 332         memset(&child, 0, sizeof(child));
 333         child.use_shell = 1;
 334         child.argv = argv;
 335         child.no_stdin = 1;
 336         child.no_stderr = 1;
 337         child.out = -1;
 338         if (start_command(&child)) {
 339                 logerror("daemon access hook '%s' failed to start",
 340                          access_hook);
 341                 goto error_return;
 342         }
 343         if (strbuf_read(&buf, child.out, 0) < 0) {
 344                 logerror("failed to read from pipe to daemon access hook '%s'",
 345                          access_hook);
 346                 strbuf_reset(&buf);
 347                 seen_errors = 1;
 348         }
 349         if (close(child.out) < 0) {
 350                 logerror("failed to close pipe to daemon access hook '%s'",
 351                          access_hook);
 352                 seen_errors = 1;
 353         }
 354         if (finish_command(&child))
 355                 seen_errors = 1;
 356
 357         if (!seen_errors) {
 358                 strbuf_release(&buf);
 359                 return 0;
 360         }
 361
 362 error_return:
 363         strbuf_ltrim(&buf);
 364         if (!buf.len)
 365                 strbuf_addstr(&buf, "service rejected");
 366         eol = strchr(buf.buf, '\n');
 367         if (eol)
 368                 *eol = '\0';
 369         errno = EACCES;
 370         daemon_error(dir, buf.buf);
 371         strbuf_release(&buf);
 372         return -1;
 373 }
 374
 375 static int run_service(const char *dir, struct daemon_service *service)
 376 {
 377         const char *path;
 378         int enabled = service->enabled;
 379
 380         loginfo("Request %s for '%s'", service->name, dir);
 381
 382         if (!enabled && !service->overridable) {
 383                 logerror("'%s': service not enabled.", service->name);
 384                 errno = EACCES;
 385                 return daemon_error(dir, "service not enabled");
 386         }
 387
 388         if (!(path = path_ok(dir)))
 389                 return daemon_error(dir, "no such repository");
 390
 391         /*
 392          * Security on the cheap.
 393          *
 394          * We want a readable HEAD, usable "objects" directory, and
 395          * a "git-daemon-export-ok" flag that says that the other side
 396          * is ok with us doing this.
 397          *
 398          * path_ok() uses enter_repo() and does whitelist checking.
 399          * We only need to make sure the repository is exported.
 400          */
 401
 402         if (!export_all_trees && access("git-daemon-export-ok", F_OK)) {
 403                 logerror("'%s': repository not exported.", path);
 404                 errno = EACCES;
 405                 return daemon_error(dir, "repository not exported");
 406         }
 407
 408         if (service->overridable) {
 409                 service_looking_at = service;
 410                 service_enabled = -1;
 411                 git_config(git_daemon_config, NULL);
 412                 if (0 <= service_enabled)
 413                         enabled = service_enabled;
 414         }
 415         if (!enabled) {
 416                 logerror("'%s': service not enabled for '%s'",
 417                          service->name, path);
 418                 errno = EACCES;
 419                 return daemon_error(dir, "service not enabled");
 420         }
 421
 422         /*
 423          * Optionally, a hook can choose to deny access to the
 424          * repository depending on the phase of the moon.
 425          */
 426         if (access_hook && run_access_hook(service, dir, path))
 427                 return -1;
 428
 429         /*
 430          * We'll ignore SIGTERM from now on, we have a
 431          * good client.
 432          */
 433         signal(SIGTERM, SIG_IGN);
 434
 435         return service->fn();
 436 }
 437
 438 static void copy_to_log(int fd)
 439 {
 440         struct strbuf line = STRBUF_INIT;
 441         FILE *fp;
 442
 443         fp = fdopen(fd, "r");
 444         if (fp == NULL) {
 445                 logerror("fdopen of error channel failed");
 446                 close(fd);
 447                 return;
 448         }
 449
 450         while (strbuf_getline(&line, fp, '\n') != EOF) {
 451                 logerror("%s", line.buf);
 452                 strbuf_setlen(&line, 0);
 453         }
 454
 455         strbuf_release(&line);
 456         fclose(fp);
 457 }
 458
 459 static int run_service_command(const char **argv)
 460 {
 461         struct child_process cld;
 462
 463         memset(&cld, 0, sizeof(cld));
 464         cld.argv = argv;
 465         cld.git_cmd = 1;
 466         cld.err = -1;
 467         if (start_command(&cld))
 468                 return -1;
 469
 470         close(0);
 471         close(1);
 472
 473         copy_to_log(cld.err);
 474
 475         return finish_command(&cld);
 476 }
 477
 478 static int upload_pack(void)
 479 {
 480         /* Timeout as string */
 481         char timeout_buf[64];
 482         const char *argv[] = { "upload-pack", "--strict", NULL, ".", NULL };
 483
 484         argv[2] = timeout_buf;
 485
 486         snprintf(timeout_buf, sizeof timeout_buf, "--timeout=%u", timeout);
 487         return run_service_command(argv);
 488 }
 489
 490 static int upload_archive(void)
 491 {
 492         static const char *argv[] = { "upload-archive", ".", NULL };
 493         return run_service_command(argv);
 494 }
 495
 496 static int receive_pack(void)
 497 {
 498         static const char *argv[] = { "receive-pack", ".", NULL };
 499         return run_service_command(argv);
 500 }
 501
 502 static struct daemon_service daemon_service[] = {
 503         { "upload-archive", "uploadarch", upload_archive, 0, 1 },
 504         { "upload-pack", "uploadpack", upload_pack, 1, 1 },
 505         { "receive-pack", "receivepack", receive_pack, 0, 1 },
 506 };
 507
 508 static void enable_service(const char *name, int ena)
 509 {
 510         int i;
 511         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 512                 if (!strcmp(daemon_service[i].name, name)) {
 513                         daemon_service[i].enabled = ena;
 514                         return;
 515                 }
 516         }
 517         die("No such service %s", name);
 518 }
 519
 520 static void make_service_overridable(const char *name, int ena)
 521 {
 522         int i;
 523         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 524                 if (!strcmp(daemon_service[i].name, name)) {
 525                         daemon_service[i].overridable = ena;
 526                         return;
 527                 }
 528         }
 529         die("No such service %s", name);
 530 }
 531
 532 static void parse_host_and_port(char *hostport, char **host,
 533         char **port)
 534 {
 535         if (*hostport == '[') {
 536                 char *end;
 537
 538                 end = strchr(hostport, ']');
 539                 if (!end)
 540                         die("Invalid request ('[' without ']')");
 541                 *end = '\0';
 542                 *host = hostport + 1;
 543                 if (!end[1])
 544                         *port = NULL;
 545                 else if (end[1] == ':')
 546                         *port = end + 2;
 547                 else
 548                         die("Garbage after end of host part");
 549         } else {
 550                 *host = hostport;
 551                 *port = strrchr(hostport, ':');
 552                 if (*port) {
 553                         **port = '\0';
 554                         ++*port;
 555                 }
 556         }
 557 }
 558
 559 /*
 560  * Read the host as supplied by the client connection.
 561  */
 562 static void parse_host_arg(char *extra_args, int buflen)
 563 {
 564         char *val;
 565         int vallen;
 566         char *end = extra_args + buflen;
 567
 568         if (extra_args < end && *extra_args) {
 569                 saw_extended_args = 1;
 570                 if (strncasecmp("host=", extra_args, 5) == 0) {
 571                         val = extra_args + 5;
 572                         vallen = strlen(val) + 1;
 573                         if (*val) {
 574                                 /* Split <host>:<port> at colon. */
 575                                 char *host;
 576                                 char *port;
 577                                 parse_host_and_port(val, &host, &port);
 578                                 if (port) {
 579                                         free(tcp_port);
 580                                         tcp_port = xstrdup(port);
 581                                 }
 582                                 free(hostname);
 583                                 hostname = xstrdup_tolower(host);
 584                                 hostname_lookup_done = 0;
 585                         }
 586
 587                         /* On to the next one */
 588                         extra_args = val + vallen;
 589                 }
 590                 if (extra_args < end && *extra_args)
 591                         die("Invalid request");
 592         }
 593 }
 594
 595 /*
 596  * Locate canonical hostname and its IP address.
 597  */
 598 static void lookup_hostname(void)
 599 {
 600         if (!hostname_lookup_done && hostname) {
 601 #ifndef NO_IPV6
 602                 struct addrinfo hints;
 603                 struct addrinfo *ai;
 604                 int gai;
 605                 static char addrbuf[HOST_NAME_MAX + 1];
 606
 607                 memset(&hints, 0, sizeof(hints));
 608                 hints.ai_flags = AI_CANONNAME;
 609
 610                 gai = getaddrinfo(hostname, NULL, &hints, &ai);
 611                 if (!gai) {
 612                         struct sockaddr_in *sin_addr = (void *)ai->ai_addr;
 613
 614                         inet_ntop(AF_INET, &sin_addr->sin_addr,
 615                                   addrbuf, sizeof(addrbuf));
 616                         free(ip_address);
 617                         ip_address = xstrdup(addrbuf);
 618
 619                         free(canon_hostname);
 620                         canon_hostname = xstrdup(ai->ai_canonname ?
 621                                                  ai->ai_canonname : ip_address);
 622
 623                         freeaddrinfo(ai);
 624                 }
 625 #else
 626                 struct hostent *hent;
 627                 struct sockaddr_in sa;
 628                 char **ap;
 629                 static char addrbuf[HOST_NAME_MAX + 1];
 630
 631                 hent = gethostbyname(hostname);
 632                 if (hent) {
 633                         ap = hent->h_addr_list;
 634                         memset(&sa, 0, sizeof sa);
 635                         sa.sin_family = hent->h_addrtype;
 636                         sa.sin_port = htons(0);
 637                         memcpy(&sa.sin_addr, *ap, hent->h_length);
 638
 639                         inet_ntop(hent->h_addrtype, &sa.sin_addr,
 640                                   addrbuf, sizeof(addrbuf));
 641
 642                         free(canon_hostname);
 643                         canon_hostname = xstrdup(hent->h_name);
 644                         free(ip_address);
 645                         ip_address = xstrdup(addrbuf);
 646                 }
 647 #endif
 648                 hostname_lookup_done = 1;
 649         }
 650 }
 651
 652
 653 static int execute(void)
 654 {
 655         char *line = packet_buffer;
 656         int pktlen, len, i;
 657         char *addr = getenv("REMOTE_ADDR"), *port = getenv("REMOTE_PORT");
 658
 659         if (addr)
 660                 loginfo("Connection from %s:%s", addr, port);
 661
 662         alarm(init_timeout ? init_timeout : timeout);
 663         pktlen = packet_read(0, NULL, NULL, packet_buffer, sizeof(packet_buffer), 0);
 664         alarm(0);
 665
 666         len = strlen(line);
 667         if (pktlen != len)
 668                 loginfo("Extended attributes (%d bytes) exist <%.*s>",
 669                         (int) pktlen - len,
 670                         (int) pktlen - len, line + len + 1);
 671         if (len && line[len-1] == '\n') {
 672                 line[--len] = 0;
 673                 pktlen--;
 674         }
 675
 676         free(hostname);
 677         free(canon_hostname);
 678         free(ip_address);
 679         free(tcp_port);
 680         hostname = canon_hostname = ip_address = tcp_port = NULL;
 681
 682         if (len != pktlen)
 683                 parse_host_arg(line + len + 1, pktlen - len - 1);
 684
 685         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 686                 struct daemon_service *s = &(daemon_service[i]);
 687                 const char *arg;
 688
 689                 if (skip_prefix(line, "git-", &arg) &&
 690                     skip_prefix(arg, s->name, &arg) &&
 691                     *arg++ == ' ') {
 692                         /*
 693                          * Note: The directory here is probably context sensitive,
 694                          * and might depend on the actual service being performed.
 695                          */
 696                         return run_service(arg, s);
 697                 }
 698         }
 699
 700         logerror("Protocol error: '%s'", line);
 701         return -1;
 702 }
 703
 704 static int addrcmp(const struct sockaddr_storage *s1,
 705     const struct sockaddr_storage *s2)
 706 {
 707         const struct sockaddr *sa1 = (const struct sockaddr*) s1;
 708         const struct sockaddr *sa2 = (const struct sockaddr*) s2;
 709
 710         if (sa1->sa_family != sa2->sa_family)
 711                 return sa1->sa_family - sa2->sa_family;
 712         if (sa1->sa_family == AF_INET)
 713                 return memcmp(&((struct sockaddr_in *)s1)->sin_addr,
 714                     &((struct sockaddr_in *)s2)->sin_addr,
 715                     sizeof(struct in_addr));
 716 #ifndef NO_IPV6
 717         if (sa1->sa_family == AF_INET6)
 718                 return memcmp(&((struct sockaddr_in6 *)s1)->sin6_addr,
 719                     &((struct sockaddr_in6 *)s2)->sin6_addr,
 720                     sizeof(struct in6_addr));
 721 #endif
 722         return 0;
 723 }
 724
 725 static int max_connections = 32;
 726
 727 static unsigned int live_children;
 728
 729 static struct child {
 730         struct child *next;
 731         struct child_process cld;
 732         struct sockaddr_storage address;
 733 } *firstborn;
 734
 735 static void add_child(struct child_process *cld, struct sockaddr *addr, socklen_t addrlen)
 736 {
 737         struct child *newborn, **cradle;
 738
 739         newborn = xcalloc(1, sizeof(*newborn));
 740         live_children++;
 741         memcpy(&newborn->cld, cld, sizeof(*cld));
 742         memcpy(&newborn->address, addr, addrlen);
 743         for (cradle = &firstborn; *cradle; cradle = &(*cradle)->next)
 744                 if (!addrcmp(&(*cradle)->address, &newborn->address))
 745                         break;
 746         newborn->next = *cradle;
 747         *cradle = newborn;
 748 }
 749
 750 /*
 751  * This gets called if the number of connections grows
 752  * past "max_connections".
 753  *
 754  * We kill the newest connection from a duplicate IP.
 755  */
 756 static void kill_some_child(void)
 757 {
 758         const struct child *blanket, *next;
 759
 760         if (!(blanket = firstborn))
 761                 return;
 762
 763         for (; (next = blanket->next); blanket = next)
 764                 if (!addrcmp(&blanket->address, &next->address)) {
 765                         kill(blanket->cld.pid, SIGTERM);
 766                         break;
 767                 }
 768 }
 769
 770 static void check_dead_children(void)
 771 {
 772         int status;
 773         pid_t pid;
 774
 775         struct child **cradle, *blanket;
 776         for (cradle = &firstborn; (blanket = *cradle);)
 777                 if ((pid = waitpid(blanket->cld.pid, &status, WNOHANG)) > 1) {
 778                         const char *dead = "";
 779                         if (status)
 780                                 dead = " (with error)";
 781                         loginfo("[%"PRIuMAX"] Disconnected%s", (uintmax_t)pid, dead);
 782
 783                         /* remove the child */
 784                         *cradle = blanket->next;
 785                         live_children--;
 786                         free(blanket);
 787                 } else
 788                         cradle = &blanket->next;
 789 }
 790
 791 static char **cld_argv;
 792 static void handle(int incoming, struct sockaddr *addr, socklen_t addrlen)
 793 {
 794         struct child_process cld = { NULL };
 795         char addrbuf[300] = "REMOTE_ADDR=", portbuf[300];
 796         char *env[] = { addrbuf, portbuf, NULL };
 797
 798         if (max_connections && live_children >= max_connections) {
 799                 kill_some_child();
 800                 sleep(1);  /* give it some time to die */
 801                 check_dead_children();
 802                 if (live_children >= max_connections) {
 803                         close(incoming);
 804                         logerror("Too many children, dropping connection");
 805                         return;
 806                 }
 807         }
 808
 809         if (addr->sa_family == AF_INET) {
 810                 struct sockaddr_in *sin_addr = (void *) addr;
 811                 inet_ntop(addr->sa_family, &sin_addr->sin_addr, addrbuf + 12,
 812                     sizeof(addrbuf) - 12);
 813                 snprintf(portbuf, sizeof(portbuf), "REMOTE_PORT=%d",
 814                     ntohs(sin_addr->sin_port));
 815 #ifndef NO_IPV6
 816         } else if (addr->sa_family == AF_INET6) {
 817                 struct sockaddr_in6 *sin6_addr = (void *) addr;
 818
 819                 char *buf = addrbuf + 12;
 820                 *buf++ = '['; *buf = '\0'; /* stpcpy() is cool */
 821                 inet_ntop(AF_INET6, &sin6_addr->sin6_addr, buf,
 822                     sizeof(addrbuf) - 13);
 823                 strcat(buf, "]");
 824
 825                 snprintf(portbuf, sizeof(portbuf), "REMOTE_PORT=%d",
 826                     ntohs(sin6_addr->sin6_port));
 827 #endif
 828         }
 829
 830         cld.env = (const char **)env;
 831         cld.argv = (const char **)cld_argv;
 832         cld.in = incoming;
 833         cld.out = dup(incoming);
 834
 835         if (start_command(&cld))
 836                 logerror("unable to fork");
 837         else
 838                 add_child(&cld, addr, addrlen);
 839 }
 840
 841 static void child_handler(int signo)
 842 {
 843         /*
 844          * Otherwise empty handler because systemcalls will get interrupted
 845          * upon signal receipt
 846          * SysV needs the handler to be rearmed
 847          */
 848         signal(SIGCHLD, child_handler);
 849 }
 850
 851 static int set_reuse_addr(int sockfd)
 852 {
 853         int on = 1;
 854
 855         if (!reuseaddr)
 856                 return 0;
 857         return setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
 858                           &on, sizeof(on));
 859 }
 860
 861 struct socketlist {
 862         int *list;
 863         size_t nr;
 864         size_t alloc;
 865 };
 866
 867 static const char *ip2str(int family, struct sockaddr *sin, socklen_t len)
 868 {
 869 #ifdef NO_IPV6
 870         static char ip[INET_ADDRSTRLEN];
 871 #else
 872         static char ip[INET6_ADDRSTRLEN];
 873 #endif
 874
 875         switch (family) {
 876 #ifndef NO_IPV6
 877         case AF_INET6:
 878                 inet_ntop(family, &((struct sockaddr_in6*)sin)->sin6_addr, ip, len);
 879                 break;
 880 #endif
 881         case AF_INET:
 882                 inet_ntop(family, &((struct sockaddr_in*)sin)->sin_addr, ip, len);
 883                 break;
 884         default:
 885                 strcpy(ip, "<unknown>");
 886         }
 887         return ip;
 888 }
 889
 890 #ifndef NO_IPV6
 891
 892 static int setup_named_sock(char *listen_addr, int listen_port, struct socketlist *socklist)
 893 {
 894         int socknum = 0;
 895         char pbuf[NI_MAXSERV];
 896         struct addrinfo hints, *ai0, *ai;
 897         int gai;
 898         long flags;
 899
 900         sprintf(pbuf, "%d", listen_port);
 901         memset(&hints, 0, sizeof(hints));
 902         hints.ai_family = AF_UNSPEC;
 903         hints.ai_socktype = SOCK_STREAM;
 904         hints.ai_protocol = IPPROTO_TCP;
 905         hints.ai_flags = AI_PASSIVE;
 906
 907         gai = getaddrinfo(listen_addr, pbuf, &hints, &ai0);
 908         if (gai) {
 909                 logerror("getaddrinfo() for %s failed: %s", listen_addr, gai_strerror(gai));
 910                 return 0;
 911         }
 912
 913         for (ai = ai0; ai; ai = ai->ai_next) {
 914                 int sockfd;
 915
 916                 sockfd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
 917                 if (sockfd < 0)
 918                         continue;
 919                 if (sockfd >= FD_SETSIZE) {
 920                         logerror("Socket descriptor too large");
 921                         close(sockfd);
 922                         continue;
 923                 }
 924
 925 #ifdef IPV6_V6ONLY
 926                 if (ai->ai_family == AF_INET6) {
 927                         int on = 1;
 928                         setsockopt(sockfd, IPPROTO_IPV6, IPV6_V6ONLY,
 929                                    &on, sizeof(on));
 930                         /* Note: error is not fatal */
 931                 }
 932 #endif
 933
 934                 if (set_reuse_addr(sockfd)) {
 935                         logerror("Could not set SO_REUSEADDR: %s", strerror(errno));
 936                         close(sockfd);
 937                         continue;
 938                 }
 939
 940                 if (bind(sockfd, ai->ai_addr, ai->ai_addrlen) < 0) {
 941                         logerror("Could not bind to %s: %s",
 942                                  ip2str(ai->ai_family, ai->ai_addr, ai->ai_addrlen),
 943                                  strerror(errno));
 944                         close(sockfd);
 945                         continue;       /* not fatal */
 946                 }
 947                 if (listen(sockfd, 5) < 0) {
 948                         logerror("Could not listen to %s: %s",
 949                                  ip2str(ai->ai_family, ai->ai_addr, ai->ai_addrlen),
 950                                  strerror(errno));
 951                         close(sockfd);
 952                         continue;       /* not fatal */
 953                 }
 954
 955                 flags = fcntl(sockfd, F_GETFD, 0);
 956                 if (flags >= 0)
 957                         fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
 958
 959                 ALLOC_GROW(socklist->list, socklist->nr + 1, socklist->alloc);
 960                 socklist->list[socklist->nr++] = sockfd;
 961                 socknum++;
 962         }
 963
 964         freeaddrinfo(ai0);
 965
 966         return socknum;
 967 }
 968
 969 #else /* NO_IPV6 */
 970
 971 static int setup_named_sock(char *listen_addr, int listen_port, struct socketlist *socklist)
 972 {
 973         struct sockaddr_in sin;
 974         int sockfd;
 975         long flags;
 976
 977         memset(&sin, 0, sizeof sin);
 978         sin.sin_family = AF_INET;
 979         sin.sin_port = htons(listen_port);
 980
 981         if (listen_addr) {
 982                 /* Well, host better be an IP address here. */
 983                 if (inet_pton(AF_INET, listen_addr, &sin.sin_addr.s_addr) <= 0)
 984                         return 0;
 985         } else {
 986                 sin.sin_addr.s_addr = htonl(INADDR_ANY);
 987         }
 988
 989         sockfd = socket(AF_INET, SOCK_STREAM, 0);
 990         if (sockfd < 0)
 991                 return 0;
 992
 993         if (set_reuse_addr(sockfd)) {
 994                 logerror("Could not set SO_REUSEADDR: %s", strerror(errno));
 995                 close(sockfd);
 996                 return 0;
 997         }
 998
 999         if ( bind(sockfd, (struct sockaddr *)&sin, sizeof sin) < 0 ) {
1000                 logerror("Could not bind to %s: %s",
1001                          ip2str(AF_INET, (struct sockaddr *)&sin, sizeof(sin)),
1002                          strerror(errno));
1003                 close(sockfd);
1004                 return 0;
1005         }
1006
1007         if (listen(sockfd, 5) < 0) {
1008                 logerror("Could not listen to %s: %s",
1009                          ip2str(AF_INET, (struct sockaddr *)&sin, sizeof(sin)),
1010                          strerror(errno));
1011                 close(sockfd);
1012                 return 0;
1013         }
1014
1015         flags = fcntl(sockfd, F_GETFD, 0);
1016         if (flags >= 0)
1017                 fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
1018
1019         ALLOC_GROW(socklist->list, socklist->nr + 1, socklist->alloc);
1020         socklist->list[socklist->nr++] = sockfd;
1021         return 1;
1022 }
1023
1024 #endif
1025
1026 static void socksetup(struct string_list *listen_addr, int listen_port, struct socketlist *socklist)
1027 {
1028         if (!listen_addr->nr)
1029                 setup_named_sock(NULL, listen_port, socklist);
1030         else {
1031                 int i, socknum;
1032                 for (i = 0; i < listen_addr->nr; i++) {
1033                         socknum = setup_named_sock(listen_addr->items[i].string,
1034                                                    listen_port, socklist);
1035
1036                         if (socknum == 0)
1037                                 logerror("unable to allocate any listen sockets for host %s on port %u",
1038                                          listen_addr->items[i].string, listen_port);
1039                 }
1040         }
1041 }
1042
1043 static int service_loop(struct socketlist *socklist)
1044 {
1045         struct pollfd *pfd;
1046         int i;
1047
1048         pfd = xcalloc(socklist->nr, sizeof(struct pollfd));
1049
1050         for (i = 0; i < socklist->nr; i++) {
1051                 pfd[i].fd = socklist->list[i];
1052                 pfd[i].events = POLLIN;
1053         }
1054
1055         signal(SIGCHLD, child_handler);
1056
1057         for (;;) {
1058                 int i;
1059
1060                 check_dead_children();
1061
1062                 if (poll(pfd, socklist->nr, -1) < 0) {
1063                         if (errno != EINTR) {
1064                                 logerror("Poll failed, resuming: %s",
1065                                       strerror(errno));
1066                                 sleep(1);
1067                         }
1068                         continue;
1069                 }
1070
1071                 for (i = 0; i < socklist->nr; i++) {
1072                         if (pfd[i].revents & POLLIN) {
1073                                 union {
1074                                         struct sockaddr sa;
1075                                         struct sockaddr_in sai;
1076 #ifndef NO_IPV6
1077                                         struct sockaddr_in6 sai6;
1078 #endif
1079                                 } ss;
1080                                 socklen_t sslen = sizeof(ss);
1081                                 int incoming = accept(pfd[i].fd, &ss.sa, &sslen);
1082                                 if (incoming < 0) {
1083                                         switch (errno) {
1084                                         case EAGAIN:
1085                                         case EINTR:
1086                                         case ECONNABORTED:
1087                                                 continue;
1088                                         default:
1089                                                 die_errno("accept returned");
1090                                         }
1091                                 }
1092                                 handle(incoming, &ss.sa, sslen);
1093                         }
1094                 }
1095         }
1096 }
1097
1098 #ifdef NO_POSIX_GOODIES
1099
1100 struct credentials;
1101
1102 static void drop_privileges(struct credentials *cred)
1103 {
1104         /* nothing */
1105 }
1106
1107 static struct credentials *prepare_credentials(const char *user_name,
1108     const char *group_name)
1109 {
1110         die("--user not supported on this platform");
1111 }
1112
1113 #else
1114
1115 struct credentials {
1116         struct passwd *pass;
1117         gid_t gid;
1118 };
1119
1120 static void drop_privileges(struct credentials *cred)
1121 {
1122         if (cred && (initgroups(cred->pass->pw_name, cred->gid) ||
1123             setgid (cred->gid) || setuid(cred->pass->pw_uid)))
1124                 die("cannot drop privileges");
1125 }
1126
1127 static struct credentials *prepare_credentials(const char *user_name,
1128     const char *group_name)
1129 {
1130         static struct credentials c;
1131
1132         c.pass = getpwnam(user_name);
1133         if (!c.pass)
1134                 die("user not found - %s", user_name);
1135
1136         if (!group_name)
1137                 c.gid = c.pass->pw_gid;
1138         else {
1139                 struct group *group = getgrnam(group_name);
1140                 if (!group)
1141                         die("group not found - %s", group_name);
1142
1143                 c.gid = group->gr_gid;
1144         }
1145
1146         return &c;
1147 }
1148 #endif
1149
1150 static void store_pid(const char *path)
1151 {
1152         FILE *f = fopen(path, "w");
1153         if (!f)
1154                 die_errno("cannot open pid file '%s'", path);
1155         if (fprintf(f, "%"PRIuMAX"\n", (uintmax_t) getpid()) < 0 || fclose(f) != 0)
1156                 die_errno("failed to write pid file '%s'", path);
1157 }
1158
1159 static int serve(struct string_list *listen_addr, int listen_port,
1160     struct credentials *cred)
1161 {
1162         struct socketlist socklist = { NULL, 0, 0 };
1163
1164         socksetup(listen_addr, listen_port, &socklist);
1165         if (socklist.nr == 0)
1166                 die("unable to allocate any listen sockets on port %u",
1167                     listen_port);
1168
1169         drop_privileges(cred);
1170
1171         loginfo("Ready to rumble");
1172
1173         return service_loop(&socklist);
1174 }
1175
1176 int main(int argc, char **argv)
1177 {
1178         int listen_port = 0;
1179         struct string_list listen_addr = STRING_LIST_INIT_NODUP;
1180         int serve_mode = 0, inetd_mode = 0;
1181         const char *pid_file = NULL, *user_name = NULL, *group_name = NULL;
1182         int detach = 0;
1183         struct credentials *cred = NULL;
1184         int i;
1185
1186         git_setup_gettext();
1187
1188         git_extract_argv0_path(argv[0]);
1189
1190         for (i = 1; i < argc; i++) {
1191                 char *arg = argv[i];
1192                 const char *v;
1193
1194                 if (skip_prefix(arg, "--listen=", &v)) {
1195                         string_list_append(&listen_addr, xstrdup_tolower(v));
1196                         continue;
1197                 }
1198                 if (skip_prefix(arg, "--port=", &v)) {
1199                         char *end;
1200                         unsigned long n;
1201                         n = strtoul(v, &end, 0);
1202                         if (*v && !*end) {
1203                                 listen_port = n;
1204                                 continue;
1205                         }
1206                 }
1207                 if (!strcmp(arg, "--serve")) {
1208                         serve_mode = 1;
1209                         continue;
1210                 }
1211                 if (!strcmp(arg, "--inetd")) {
1212                         inetd_mode = 1;
1213                         log_syslog = 1;
1214                         continue;
1215                 }
1216                 if (!strcmp(arg, "--verbose")) {
1217                         verbose = 1;
1218                         continue;
1219                 }
1220                 if (!strcmp(arg, "--syslog")) {
1221                         log_syslog = 1;
1222                         continue;
1223                 }
1224                 if (!strcmp(arg, "--export-all")) {
1225                         export_all_trees = 1;
1226                         continue;
1227                 }
1228                 if (skip_prefix(arg, "--access-hook=", &v)) {
1229                         access_hook = v;
1230                         continue;
1231                 }
1232                 if (skip_prefix(arg, "--timeout=", &v)) {
1233                         timeout = atoi(v);
1234                         continue;
1235                 }
1236                 if (skip_prefix(arg, "--init-timeout=", &v)) {
1237                         init_timeout = atoi(v);
1238                         continue;
1239                 }
1240                 if (skip_prefix(arg, "--max-connections=", &v)) {
1241                         max_connections = atoi(v);
1242                         if (max_connections < 0)
1243                                 max_connections = 0;            /* unlimited */
1244                         continue;
1245                 }
1246                 if (!strcmp(arg, "--strict-paths")) {
1247                         strict_paths = 1;
1248                         continue;
1249                 }
1250                 if (skip_prefix(arg, "--base-path=", &v)) {
1251                         base_path = v;
1252                         continue;
1253                 }
1254                 if (!strcmp(arg, "--base-path-relaxed")) {
1255                         base_path_relaxed = 1;
1256                         continue;
1257                 }
1258                 if (skip_prefix(arg, "--interpolated-path=", &v)) {
1259                         interpolated_path = v;
1260                         continue;
1261                 }
1262                 if (!strcmp(arg, "--reuseaddr")) {
1263                         reuseaddr = 1;
1264                         continue;
1265                 }
1266                 if (!strcmp(arg, "--user-path")) {
1267                         user_path = "";
1268                         continue;
1269                 }
1270                 if (skip_prefix(arg, "--user-path=", &v)) {
1271                         user_path = v;
1272                         continue;
1273                 }
1274                 if (skip_prefix(arg, "--pid-file=", &v)) {
1275                         pid_file = v;
1276                         continue;
1277                 }
1278                 if (!strcmp(arg, "--detach")) {
1279                         detach = 1;
1280                         log_syslog = 1;
1281                         continue;
1282                 }
1283                 if (skip_prefix(arg, "--user=", &v)) {
1284                         user_name = v;
1285                         continue;
1286                 }
1287                 if (skip_prefix(arg, "--group=", &v)) {
1288                         group_name = v;
1289                         continue;
1290                 }
1291                 if (skip_prefix(arg, "--enable=", &v)) {
1292                         enable_service(v, 1);
1293                         continue;
1294                 }
1295                 if (skip_prefix(arg, "--disable=", &v)) {
1296                         enable_service(v, 0);
1297                         continue;
1298                 }
1299                 if (skip_prefix(arg, "--allow-override=", &v)) {
1300                         make_service_overridable(v, 1);
1301                         continue;
1302                 }
1303                 if (skip_prefix(arg, "--forbid-override=", &v)) {
1304                         make_service_overridable(v, 0);
1305                         continue;
1306                 }
1307                 if (!strcmp(arg, "--informative-errors")) {
1308                         informative_errors = 1;
1309                         continue;
1310                 }
1311                 if (!strcmp(arg, "--no-informative-errors")) {
1312                         informative_errors = 0;
1313                         continue;
1314                 }
1315                 if (!strcmp(arg, "--")) {
1316                         ok_paths = &argv[i+1];
1317                         break;
1318                 } else if (arg[0] != '-') {
1319                         ok_paths = &argv[i];
1320                         break;
1321                 }
1322
1323                 usage(daemon_usage);
1324         }
1325
1326         if (log_syslog) {
1327                 openlog("git-daemon", LOG_PID, LOG_DAEMON);
1328                 set_die_routine(daemon_die);
1329         } else
1330                 /* avoid splitting a message in the middle */
1331                 setvbuf(stderr, NULL, _IOFBF, 4096);
1332
1333         if (inetd_mode && (detach || group_name || user_name))
1334                 die("--detach, --user and --group are incompatible with --inetd");
1335
1336         if (inetd_mode && (listen_port || (listen_addr.nr > 0)))
1337                 die("--listen= and --port= are incompatible with --inetd");
1338         else if (listen_port == 0)
1339                 listen_port = DEFAULT_GIT_PORT;
1340
1341         if (group_name && !user_name)
1342                 die("--group supplied without --user");
1343
1344         if (user_name)
1345                 cred = prepare_credentials(user_name, group_name);
1346
1347         if (strict_paths && (!ok_paths || !*ok_paths))
1348                 die("option --strict-paths requires a whitelist");
1349
1350         if (base_path && !is_directory(base_path))
1351                 die("base-path '%s' does not exist or is not a directory",
1352                     base_path);
1353
1354         if (inetd_mode) {
1355                 if (!freopen("/dev/null", "w", stderr))
1356                         die_errno("failed to redirect stderr to /dev/null");
1357         }
1358
1359         if (inetd_mode || serve_mode)
1360                 return execute();
1361
1362         if (detach) {
1363                 if (daemonize())
1364                         die("--detach not supported on this platform");
1365         } else
1366                 sanitize_stdfds();
1367
1368         if (pid_file)
1369                 store_pid(pid_file);
1370
1371         /* prepare argv for serving-processes */
1372         cld_argv = xmalloc(sizeof (char *) * (argc + 2));
1373         cld_argv[0] = argv[0];  /* git-daemon */
1374         cld_argv[1] = "--serve";
1375         for (i = 1; i < argc; ++i)
1376                 cld_argv[i+1] = argv[i];
1377         cld_argv[argc+1] = NULL;
1378
1379         return serve(&listen_addr, listen_port, cred);
1380 }