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 int daemon_error(const char *dir, const char *msg)
 286 {
 287         if (!informative_errors)
 288                 msg = "access denied or repository not exported";
 289         packet_write(1, "ERR %s: %s", msg, dir);
 290         return -1;
 291 }
 292
 293 static const char *access_hook;
 294
 295 static int run_access_hook(struct daemon_service *service, const char *dir, const char *path)
 296 {
 297         struct child_process child = CHILD_PROCESS_INIT;
 298         struct strbuf buf = STRBUF_INIT;
 299         const char *argv[8];
 300         const char **arg = argv;
 301         char *eol;
 302         int seen_errors = 0;
 303
 304 #define STRARG(x) ((x) ? (x) : "")
 305         *arg++ = access_hook;
 306         *arg++ = service->name;
 307         *arg++ = path;
 308         *arg++ = STRARG(hostname);
 309         *arg++ = STRARG(get_canon_hostname());
 310         *arg++ = STRARG(get_ip_address());
 311         *arg++ = STRARG(tcp_port);
 312         *arg = NULL;
 313 #undef STRARG
 314
 315         child.use_shell = 1;
 316         child.argv = argv;
 317         child.no_stdin = 1;
 318         child.no_stderr = 1;
 319         child.out = -1;
 320         if (start_command(&child)) {
 321                 logerror("daemon access hook '%s' failed to start",
 322                          access_hook);
 323                 goto error_return;
 324         }
 325         if (strbuf_read(&buf, child.out, 0) < 0) {
 326                 logerror("failed to read from pipe to daemon access hook '%s'",
 327                          access_hook);
 328                 strbuf_reset(&buf);
 329                 seen_errors = 1;
 330         }
 331         if (close(child.out) < 0) {
 332                 logerror("failed to close pipe to daemon access hook '%s'",
 333                          access_hook);
 334                 seen_errors = 1;
 335         }
 336         if (finish_command(&child))
 337                 seen_errors = 1;
 338
 339         if (!seen_errors) {
 340                 strbuf_release(&buf);
 341                 return 0;
 342         }
 343
 344 error_return:
 345         strbuf_ltrim(&buf);
 346         if (!buf.len)
 347                 strbuf_addstr(&buf, "service rejected");
 348         eol = strchr(buf.buf, '\n');
 349         if (eol)
 350                 *eol = '\0';
 351         errno = EACCES;
 352         daemon_error(dir, buf.buf);
 353         strbuf_release(&buf);
 354         return -1;
 355 }
 356
 357 static int run_service(const char *dir, struct daemon_service *service)
 358 {
 359         const char *path;
 360         int enabled = service->enabled;
 361         struct strbuf var = STRBUF_INIT;
 362
 363         loginfo("Request %s for '%s'", service->name, dir);
 364
 365         if (!enabled && !service->overridable) {
 366                 logerror("'%s': service not enabled.", service->name);
 367                 errno = EACCES;
 368                 return daemon_error(dir, "service not enabled");
 369         }
 370
 371         if (!(path = path_ok(dir)))
 372                 return daemon_error(dir, "no such repository");
 373
 374         /*
 375          * Security on the cheap.
 376          *
 377          * We want a readable HEAD, usable "objects" directory, and
 378          * a "git-daemon-export-ok" flag that says that the other side
 379          * is ok with us doing this.
 380          *
 381          * path_ok() uses enter_repo() and does whitelist checking.
 382          * We only need to make sure the repository is exported.
 383          */
 384
 385         if (!export_all_trees && access("git-daemon-export-ok", F_OK)) {
 386                 logerror("'%s': repository not exported.", path);
 387                 errno = EACCES;
 388                 return daemon_error(dir, "repository not exported");
 389         }
 390
 391         if (service->overridable) {
 392                 strbuf_addf(&var, "daemon.%s", service->config_name);
 393                 git_config_get_bool(var.buf, &enabled);
 394                 strbuf_release(&var);
 395         }
 396         if (!enabled) {
 397                 logerror("'%s': service not enabled for '%s'",
 398                          service->name, path);
 399                 errno = EACCES;
 400                 return daemon_error(dir, "service not enabled");
 401         }
 402
 403         /*
 404          * Optionally, a hook can choose to deny access to the
 405          * repository depending on the phase of the moon.
 406          */
 407         if (access_hook && run_access_hook(service, dir, path))
 408                 return -1;
 409
 410         /*
 411          * We'll ignore SIGTERM from now on, we have a
 412          * good client.
 413          */
 414         signal(SIGTERM, SIG_IGN);
 415
 416         return service->fn();
 417 }
 418
 419 static void copy_to_log(int fd)
 420 {
 421         struct strbuf line = STRBUF_INIT;
 422         FILE *fp;
 423
 424         fp = fdopen(fd, "r");
 425         if (fp == NULL) {
 426                 logerror("fdopen of error channel failed");
 427                 close(fd);
 428                 return;
 429         }
 430
 431         while (strbuf_getline(&line, fp, '\n') != EOF) {
 432                 logerror("%s", line.buf);
 433                 strbuf_setlen(&line, 0);
 434         }
 435
 436         strbuf_release(&line);
 437         fclose(fp);
 438 }
 439
 440 static int run_service_command(const char **argv)
 441 {
 442         struct child_process cld = CHILD_PROCESS_INIT;
 443
 444         cld.argv = argv;
 445         cld.git_cmd = 1;
 446         cld.err = -1;
 447         if (start_command(&cld))
 448                 return -1;
 449
 450         close(0);
 451         close(1);
 452
 453         copy_to_log(cld.err);
 454
 455         return finish_command(&cld);
 456 }
 457
 458 static int upload_pack(void)
 459 {
 460         /* Timeout as string */
 461         char timeout_buf[64];
 462         const char *argv[] = { "upload-pack", "--strict", NULL, ".", NULL };
 463
 464         argv[2] = timeout_buf;
 465
 466         snprintf(timeout_buf, sizeof timeout_buf, "--timeout=%u", timeout);
 467         return run_service_command(argv);
 468 }
 469
 470 static int upload_archive(void)
 471 {
 472         static const char *argv[] = { "upload-archive", ".", NULL };
 473         return run_service_command(argv);
 474 }
 475
 476 static int receive_pack(void)
 477 {
 478         static const char *argv[] = { "receive-pack", ".", NULL };
 479         return run_service_command(argv);
 480 }
 481
 482 static struct daemon_service daemon_service[] = {
 483         { "upload-archive", "uploadarch", upload_archive, 0, 1 },
 484         { "upload-pack", "uploadpack", upload_pack, 1, 1 },
 485         { "receive-pack", "receivepack", receive_pack, 0, 1 },
 486 };
 487
 488 static void enable_service(const char *name, int ena)
 489 {
 490         int i;
 491         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 492                 if (!strcmp(daemon_service[i].name, name)) {
 493                         daemon_service[i].enabled = ena;
 494                         return;
 495                 }
 496         }
 497         die("No such service %s", name);
 498 }
 499
 500 static void make_service_overridable(const char *name, int ena)
 501 {
 502         int i;
 503         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 504                 if (!strcmp(daemon_service[i].name, name)) {
 505                         daemon_service[i].overridable = ena;
 506                         return;
 507                 }
 508         }
 509         die("No such service %s", name);
 510 }
 511
 512 static void parse_host_and_port(char *hostport, char **host,
 513         char **port)
 514 {
 515         if (*hostport == '[') {
 516                 char *end;
 517
 518                 end = strchr(hostport, ']');
 519                 if (!end)
 520                         die("Invalid request ('[' without ']')");
 521                 *end = '\0';
 522                 *host = hostport + 1;
 523                 if (!end[1])
 524                         *port = NULL;
 525                 else if (end[1] == ':')
 526                         *port = end + 2;
 527                 else
 528                         die("Garbage after end of host part");
 529         } else {
 530                 *host = hostport;
 531                 *port = strrchr(hostport, ':');
 532                 if (*port) {
 533                         **port = '\0';
 534                         ++*port;
 535                 }
 536         }
 537 }
 538
 539 /*
 540  * Sanitize a string from the client so that it's OK to be inserted into a
 541  * filesystem path. Specifically, we disallow slashes, runs of "..", and
 542  * trailing and leading dots, which means that the client cannot escape
 543  * our base path via ".." traversal.
 544  */
 545 static void sanitize_client_strbuf(struct strbuf *out, const char *in)
 546 {
 547         for (; *in; in++) {
 548                 if (*in == '/')
 549                         continue;
 550                 if (*in == '.' && (!out->len || out->buf[out->len - 1] == '.'))
 551                         continue;
 552                 strbuf_addch(out, *in);
 553         }
 554
 555         while (out->len && out->buf[out->len - 1] == '.')
 556                 strbuf_setlen(out, out->len - 1);
 557 }
 558
 559 static char *sanitize_client(const char *in)
 560 {
 561         struct strbuf out = STRBUF_INIT;
 562         sanitize_client_strbuf(&out, in);
 563         return strbuf_detach(&out, NULL);
 564 }
 565
 566 /*
 567  * Like sanitize_client, but we also perform any canonicalization
 568  * to make life easier on the admin.
 569  */
 570 static char *canonicalize_client(const char *in)
 571 {
 572         struct strbuf out = STRBUF_INIT;
 573         sanitize_client_strbuf(&out, in);
 574         strbuf_tolower(&out);
 575         return strbuf_detach(&out, NULL);
 576 }
 577
 578 /*
 579  * Read the host as supplied by the client connection.
 580  */
 581 static void parse_host_arg(char *extra_args, int buflen)
 582 {
 583         char *val;
 584         int vallen;
 585         char *end = extra_args + buflen;
 586
 587         if (extra_args < end && *extra_args) {
 588                 saw_extended_args = 1;
 589                 if (strncasecmp("host=", extra_args, 5) == 0) {
 590                         val = extra_args + 5;
 591                         vallen = strlen(val) + 1;
 592                         if (*val) {
 593                                 /* Split <host>:<port> at colon. */
 594                                 char *host;
 595                                 char *port;
 596                                 parse_host_and_port(val, &host, &port);
 597                                 if (port) {
 598                                         free(tcp_port);
 599                                         tcp_port = sanitize_client(port);
 600                                 }
 601                                 free(hostname);
 602                                 hostname = canonicalize_client(host);
 603                                 hostname_lookup_done = 0;
 604                         }
 605
 606                         /* On to the next one */
 607                         extra_args = val + vallen;
 608                 }
 609                 if (extra_args < end && *extra_args)
 610                         die("Invalid request");
 611         }
 612 }
 613
 614 /*
 615  * Locate canonical hostname and its IP address.
 616  */
 617 static void lookup_hostname(void)
 618 {
 619         if (!hostname_lookup_done && hostname) {
 620 #ifndef NO_IPV6
 621                 struct addrinfo hints;
 622                 struct addrinfo *ai;
 623                 int gai;
 624                 static char addrbuf[HOST_NAME_MAX + 1];
 625
 626                 memset(&hints, 0, sizeof(hints));
 627                 hints.ai_flags = AI_CANONNAME;
 628
 629                 gai = getaddrinfo(hostname, NULL, &hints, &ai);
 630                 if (!gai) {
 631                         struct sockaddr_in *sin_addr = (void *)ai->ai_addr;
 632
 633                         inet_ntop(AF_INET, &sin_addr->sin_addr,
 634                                   addrbuf, sizeof(addrbuf));
 635                         free(ip_address);
 636                         ip_address = xstrdup(addrbuf);
 637
 638                         free(canon_hostname);
 639                         canon_hostname = ai->ai_canonname ?
 640                                 sanitize_client(ai->ai_canonname) :
 641                                 xstrdup(ip_address);
 642
 643                         freeaddrinfo(ai);
 644                 }
 645 #else
 646                 struct hostent *hent;
 647                 struct sockaddr_in sa;
 648                 char **ap;
 649                 static char addrbuf[HOST_NAME_MAX + 1];
 650
 651                 hent = gethostbyname(hostname);
 652                 if (hent) {
 653                         ap = hent->h_addr_list;
 654                         memset(&sa, 0, sizeof sa);
 655                         sa.sin_family = hent->h_addrtype;
 656                         sa.sin_port = htons(0);
 657                         memcpy(&sa.sin_addr, *ap, hent->h_length);
 658
 659                         inet_ntop(hent->h_addrtype, &sa.sin_addr,
 660                                   addrbuf, sizeof(addrbuf));
 661
 662                         free(canon_hostname);
 663                         canon_hostname = sanitize_client(hent->h_name);
 664                         free(ip_address);
 665                         ip_address = xstrdup(addrbuf);
 666                 }
 667 #endif
 668                 hostname_lookup_done = 1;
 669         }
 670 }
 671
 672
 673 static int execute(void)
 674 {
 675         char *line = packet_buffer;
 676         int pktlen, len, i;
 677         char *addr = getenv("REMOTE_ADDR"), *port = getenv("REMOTE_PORT");
 678
 679         if (addr)
 680                 loginfo("Connection from %s:%s", addr, port);
 681
 682         alarm(init_timeout ? init_timeout : timeout);
 683         pktlen = packet_read(0, NULL, NULL, packet_buffer, sizeof(packet_buffer), 0);
 684         alarm(0);
 685
 686         len = strlen(line);
 687         if (pktlen != len)
 688                 loginfo("Extended attributes (%d bytes) exist <%.*s>",
 689                         (int) pktlen - len,
 690                         (int) pktlen - len, line + len + 1);
 691         if (len && line[len-1] == '\n') {
 692                 line[--len] = 0;
 693                 pktlen--;
 694         }
 695
 696         free(hostname);
 697         free(canon_hostname);
 698         free(ip_address);
 699         free(tcp_port);
 700         hostname = canon_hostname = ip_address = tcp_port = NULL;
 701
 702         if (len != pktlen)
 703                 parse_host_arg(line + len + 1, pktlen - len - 1);
 704
 705         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 706                 struct daemon_service *s = &(daemon_service[i]);
 707                 const char *arg;
 708
 709                 if (skip_prefix(line, "git-", &arg) &&
 710                     skip_prefix(arg, s->name, &arg) &&
 711                     *arg++ == ' ') {
 712                         /*
 713                          * Note: The directory here is probably context sensitive,
 714                          * and might depend on the actual service being performed.
 715                          */
 716                         return run_service(arg, s);
 717                 }
 718         }
 719
 720         logerror("Protocol error: '%s'", line);
 721         return -1;
 722 }
 723
 724 static int addrcmp(const struct sockaddr_storage *s1,
 725     const struct sockaddr_storage *s2)
 726 {
 727         const struct sockaddr *sa1 = (const struct sockaddr*) s1;
 728         const struct sockaddr *sa2 = (const struct sockaddr*) s2;
 729
 730         if (sa1->sa_family != sa2->sa_family)
 731                 return sa1->sa_family - sa2->sa_family;
 732         if (sa1->sa_family == AF_INET)
 733                 return memcmp(&((struct sockaddr_in *)s1)->sin_addr,
 734                     &((struct sockaddr_in *)s2)->sin_addr,
 735                     sizeof(struct in_addr));
 736 #ifndef NO_IPV6
 737         if (sa1->sa_family == AF_INET6)
 738                 return memcmp(&((struct sockaddr_in6 *)s1)->sin6_addr,
 739                     &((struct sockaddr_in6 *)s2)->sin6_addr,
 740                     sizeof(struct in6_addr));
 741 #endif
 742         return 0;
 743 }
 744
 745 static int max_connections = 32;
 746
 747 static unsigned int live_children;
 748
 749 static struct child {
 750         struct child *next;
 751         struct child_process cld;
 752         struct sockaddr_storage address;
 753 } *firstborn;
 754
 755 static void add_child(struct child_process *cld, struct sockaddr *addr, socklen_t addrlen)
 756 {
 757         struct child *newborn, **cradle;
 758
 759         newborn = xcalloc(1, sizeof(*newborn));
 760         live_children++;
 761         memcpy(&newborn->cld, cld, sizeof(*cld));
 762         memcpy(&newborn->address, addr, addrlen);
 763         for (cradle = &firstborn; *cradle; cradle = &(*cradle)->next)
 764                 if (!addrcmp(&(*cradle)->address, &newborn->address))
 765                         break;
 766         newborn->next = *cradle;
 767         *cradle = newborn;
 768 }
 769
 770 /*
 771  * This gets called if the number of connections grows
 772  * past "max_connections".
 773  *
 774  * We kill the newest connection from a duplicate IP.
 775  */
 776 static void kill_some_child(void)
 777 {
 778         const struct child *blanket, *next;
 779
 780         if (!(blanket = firstborn))
 781                 return;
 782
 783         for (; (next = blanket->next); blanket = next)
 784                 if (!addrcmp(&blanket->address, &next->address)) {
 785                         kill(blanket->cld.pid, SIGTERM);
 786                         break;
 787                 }
 788 }
 789
 790 static void check_dead_children(void)
 791 {
 792         int status;
 793         pid_t pid;
 794
 795         struct child **cradle, *blanket;
 796         for (cradle = &firstborn; (blanket = *cradle);)
 797                 if ((pid = waitpid(blanket->cld.pid, &status, WNOHANG)) > 1) {
 798                         const char *dead = "";
 799                         if (status)
 800                                 dead = " (with error)";
 801                         loginfo("[%"PRIuMAX"] Disconnected%s", (uintmax_t)pid, dead);
 802
 803                         /* remove the child */
 804                         *cradle = blanket->next;
 805                         live_children--;
 806                         free(blanket);
 807                 } else
 808                         cradle = &blanket->next;
 809 }
 810
 811 static char **cld_argv;
 812 static void handle(int incoming, struct sockaddr *addr, socklen_t addrlen)
 813 {
 814         struct child_process cld = CHILD_PROCESS_INIT;
 815         char addrbuf[300] = "REMOTE_ADDR=", portbuf[300];
 816         char *env[] = { addrbuf, portbuf, NULL };
 817
 818         if (max_connections && live_children >= max_connections) {
 819                 kill_some_child();
 820                 sleep(1);  /* give it some time to die */
 821                 check_dead_children();
 822                 if (live_children >= max_connections) {
 823                         close(incoming);
 824                         logerror("Too many children, dropping connection");
 825                         return;
 826                 }
 827         }
 828
 829         if (addr->sa_family == AF_INET) {
 830                 struct sockaddr_in *sin_addr = (void *) addr;
 831                 inet_ntop(addr->sa_family, &sin_addr->sin_addr, addrbuf + 12,
 832                     sizeof(addrbuf) - 12);
 833                 snprintf(portbuf, sizeof(portbuf), "REMOTE_PORT=%d",
 834                     ntohs(sin_addr->sin_port));
 835 #ifndef NO_IPV6
 836         } else if (addr->sa_family == AF_INET6) {
 837                 struct sockaddr_in6 *sin6_addr = (void *) addr;
 838
 839                 char *buf = addrbuf + 12;
 840                 *buf++ = '['; *buf = '\0'; /* stpcpy() is cool */
 841                 inet_ntop(AF_INET6, &sin6_addr->sin6_addr, buf,
 842                     sizeof(addrbuf) - 13);
 843                 strcat(buf, "]");
 844
 845                 snprintf(portbuf, sizeof(portbuf), "REMOTE_PORT=%d",
 846                     ntohs(sin6_addr->sin6_port));
 847 #endif
 848         }
 849
 850         cld.env = (const char **)env;
 851         cld.argv = (const char **)cld_argv;
 852         cld.in = incoming;
 853         cld.out = dup(incoming);
 854
 855         if (start_command(&cld))
 856                 logerror("unable to fork");
 857         else
 858                 add_child(&cld, addr, addrlen);
 859 }
 860
 861 static void child_handler(int signo)
 862 {
 863         /*
 864          * Otherwise empty handler because systemcalls will get interrupted
 865          * upon signal receipt
 866          * SysV needs the handler to be rearmed
 867          */
 868         signal(SIGCHLD, child_handler);
 869 }
 870
 871 static int set_reuse_addr(int sockfd)
 872 {
 873         int on = 1;
 874
 875         if (!reuseaddr)
 876                 return 0;
 877         return setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
 878                           &on, sizeof(on));
 879 }
 880
 881 struct socketlist {
 882         int *list;
 883         size_t nr;
 884         size_t alloc;
 885 };
 886
 887 static const char *ip2str(int family, struct sockaddr *sin, socklen_t len)
 888 {
 889 #ifdef NO_IPV6
 890         static char ip[INET_ADDRSTRLEN];
 891 #else
 892         static char ip[INET6_ADDRSTRLEN];
 893 #endif
 894
 895         switch (family) {
 896 #ifndef NO_IPV6
 897         case AF_INET6:
 898                 inet_ntop(family, &((struct sockaddr_in6*)sin)->sin6_addr, ip, len);
 899                 break;
 900 #endif
 901         case AF_INET:
 902                 inet_ntop(family, &((struct sockaddr_in*)sin)->sin_addr, ip, len);
 903                 break;
 904         default:
 905                 strcpy(ip, "<unknown>");
 906         }
 907         return ip;
 908 }
 909
 910 #ifndef NO_IPV6
 911
 912 static int setup_named_sock(char *listen_addr, int listen_port, struct socketlist *socklist)
 913 {
 914         int socknum = 0;
 915         char pbuf[NI_MAXSERV];
 916         struct addrinfo hints, *ai0, *ai;
 917         int gai;
 918         long flags;
 919
 920         sprintf(pbuf, "%d", listen_port);
 921         memset(&hints, 0, sizeof(hints));
 922         hints.ai_family = AF_UNSPEC;
 923         hints.ai_socktype = SOCK_STREAM;
 924         hints.ai_protocol = IPPROTO_TCP;
 925         hints.ai_flags = AI_PASSIVE;
 926
 927         gai = getaddrinfo(listen_addr, pbuf, &hints, &ai0);
 928         if (gai) {
 929                 logerror("getaddrinfo() for %s failed: %s", listen_addr, gai_strerror(gai));
 930                 return 0;
 931         }
 932
 933         for (ai = ai0; ai; ai = ai->ai_next) {
 934                 int sockfd;
 935
 936                 sockfd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
 937                 if (sockfd < 0)
 938                         continue;
 939                 if (sockfd >= FD_SETSIZE) {
 940                         logerror("Socket descriptor too large");
 941                         close(sockfd);
 942                         continue;
 943                 }
 944
 945 #ifdef IPV6_V6ONLY
 946                 if (ai->ai_family == AF_INET6) {
 947                         int on = 1;
 948                         setsockopt(sockfd, IPPROTO_IPV6, IPV6_V6ONLY,
 949                                    &on, sizeof(on));
 950                         /* Note: error is not fatal */
 951                 }
 952 #endif
 953
 954                 if (set_reuse_addr(sockfd)) {
 955                         logerror("Could not set SO_REUSEADDR: %s", strerror(errno));
 956                         close(sockfd);
 957                         continue;
 958                 }
 959
 960                 if (bind(sockfd, ai->ai_addr, ai->ai_addrlen) < 0) {
 961                         logerror("Could not bind to %s: %s",
 962                                  ip2str(ai->ai_family, ai->ai_addr, ai->ai_addrlen),
 963                                  strerror(errno));
 964                         close(sockfd);
 965                         continue;       /* not fatal */
 966                 }
 967                 if (listen(sockfd, 5) < 0) {
 968                         logerror("Could not listen to %s: %s",
 969                                  ip2str(ai->ai_family, ai->ai_addr, ai->ai_addrlen),
 970                                  strerror(errno));
 971                         close(sockfd);
 972                         continue;       /* not fatal */
 973                 }
 974
 975                 flags = fcntl(sockfd, F_GETFD, 0);
 976                 if (flags >= 0)
 977                         fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
 978
 979                 ALLOC_GROW(socklist->list, socklist->nr + 1, socklist->alloc);
 980                 socklist->list[socklist->nr++] = sockfd;
 981                 socknum++;
 982         }
 983
 984         freeaddrinfo(ai0);
 985
 986         return socknum;
 987 }
 988
 989 #else /* NO_IPV6 */
 990
 991 static int setup_named_sock(char *listen_addr, int listen_port, struct socketlist *socklist)
 992 {
 993         struct sockaddr_in sin;
 994         int sockfd;
 995         long flags;
 996
 997         memset(&sin, 0, sizeof sin);
 998         sin.sin_family = AF_INET;
 999         sin.sin_port = htons(listen_port);
1000
1001         if (listen_addr) {
1002                 /* Well, host better be an IP address here. */
1003                 if (inet_pton(AF_INET, listen_addr, &sin.sin_addr.s_addr) <= 0)
1004                         return 0;
1005         } else {
1006                 sin.sin_addr.s_addr = htonl(INADDR_ANY);
1007         }
1008
1009         sockfd = socket(AF_INET, SOCK_STREAM, 0);
1010         if (sockfd < 0)
1011                 return 0;
1012
1013         if (set_reuse_addr(sockfd)) {
1014                 logerror("Could not set SO_REUSEADDR: %s", strerror(errno));
1015                 close(sockfd);
1016                 return 0;
1017         }
1018
1019         if ( bind(sockfd, (struct sockaddr *)&sin, sizeof sin) < 0 ) {
1020                 logerror("Could not bind to %s: %s",
1021                          ip2str(AF_INET, (struct sockaddr *)&sin, sizeof(sin)),
1022                          strerror(errno));
1023                 close(sockfd);
1024                 return 0;
1025         }
1026
1027         if (listen(sockfd, 5) < 0) {
1028                 logerror("Could not listen to %s: %s",
1029                          ip2str(AF_INET, (struct sockaddr *)&sin, sizeof(sin)),
1030                          strerror(errno));
1031                 close(sockfd);
1032                 return 0;
1033         }
1034
1035         flags = fcntl(sockfd, F_GETFD, 0);
1036         if (flags >= 0)
1037                 fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
1038
1039         ALLOC_GROW(socklist->list, socklist->nr + 1, socklist->alloc);
1040         socklist->list[socklist->nr++] = sockfd;
1041         return 1;
1042 }
1043
1044 #endif
1045
1046 static void socksetup(struct string_list *listen_addr, int listen_port, struct socketlist *socklist)
1047 {
1048         if (!listen_addr->nr)
1049                 setup_named_sock(NULL, listen_port, socklist);
1050         else {
1051                 int i, socknum;
1052                 for (i = 0; i < listen_addr->nr; i++) {
1053                         socknum = setup_named_sock(listen_addr->items[i].string,
1054                                                    listen_port, socklist);
1055
1056                         if (socknum == 0)
1057                                 logerror("unable to allocate any listen sockets for host %s on port %u",
1058                                          listen_addr->items[i].string, listen_port);
1059                 }
1060         }
1061 }
1062
1063 static int service_loop(struct socketlist *socklist)
1064 {
1065         struct pollfd *pfd;
1066         int i;
1067
1068         pfd = xcalloc(socklist->nr, sizeof(struct pollfd));
1069
1070         for (i = 0; i < socklist->nr; i++) {
1071                 pfd[i].fd = socklist->list[i];
1072                 pfd[i].events = POLLIN;
1073         }
1074
1075         signal(SIGCHLD, child_handler);
1076
1077         for (;;) {
1078                 int i;
1079
1080                 check_dead_children();
1081
1082                 if (poll(pfd, socklist->nr, -1) < 0) {
1083                         if (errno != EINTR) {
1084                                 logerror("Poll failed, resuming: %s",
1085                                       strerror(errno));
1086                                 sleep(1);
1087                         }
1088                         continue;
1089                 }
1090
1091                 for (i = 0; i < socklist->nr; i++) {
1092                         if (pfd[i].revents & POLLIN) {
1093                                 union {
1094                                         struct sockaddr sa;
1095                                         struct sockaddr_in sai;
1096 #ifndef NO_IPV6
1097                                         struct sockaddr_in6 sai6;
1098 #endif
1099                                 } ss;
1100                                 socklen_t sslen = sizeof(ss);
1101                                 int incoming = accept(pfd[i].fd, &ss.sa, &sslen);
1102                                 if (incoming < 0) {
1103                                         switch (errno) {
1104                                         case EAGAIN:
1105                                         case EINTR:
1106                                         case ECONNABORTED:
1107                                                 continue;
1108                                         default:
1109                                                 die_errno("accept returned");
1110                                         }
1111                                 }
1112                                 handle(incoming, &ss.sa, sslen);
1113                         }
1114                 }
1115         }
1116 }
1117
1118 #ifdef NO_POSIX_GOODIES
1119
1120 struct credentials;
1121
1122 static void drop_privileges(struct credentials *cred)
1123 {
1124         /* nothing */
1125 }
1126
1127 static struct credentials *prepare_credentials(const char *user_name,
1128     const char *group_name)
1129 {
1130         die("--user not supported on this platform");
1131 }
1132
1133 #else
1134
1135 struct credentials {
1136         struct passwd *pass;
1137         gid_t gid;
1138 };
1139
1140 static void drop_privileges(struct credentials *cred)
1141 {
1142         if (cred && (initgroups(cred->pass->pw_name, cred->gid) ||
1143             setgid (cred->gid) || setuid(cred->pass->pw_uid)))
1144                 die("cannot drop privileges");
1145 }
1146
1147 static struct credentials *prepare_credentials(const char *user_name,
1148     const char *group_name)
1149 {
1150         static struct credentials c;
1151
1152         c.pass = getpwnam(user_name);
1153         if (!c.pass)
1154                 die("user not found - %s", user_name);
1155
1156         if (!group_name)
1157                 c.gid = c.pass->pw_gid;
1158         else {
1159                 struct group *group = getgrnam(group_name);
1160                 if (!group)
1161                         die("group not found - %s", group_name);
1162
1163                 c.gid = group->gr_gid;
1164         }
1165
1166         return &c;
1167 }
1168 #endif
1169
1170 static void store_pid(const char *path)
1171 {
1172         FILE *f = fopen(path, "w");
1173         if (!f)
1174                 die_errno("cannot open pid file '%s'", path);
1175         if (fprintf(f, "%"PRIuMAX"\n", (uintmax_t) getpid()) < 0 || fclose(f) != 0)
1176                 die_errno("failed to write pid file '%s'", path);
1177 }
1178
1179 static int serve(struct string_list *listen_addr, int listen_port,
1180     struct credentials *cred)
1181 {
1182         struct socketlist socklist = { NULL, 0, 0 };
1183
1184         socksetup(listen_addr, listen_port, &socklist);
1185         if (socklist.nr == 0)
1186                 die("unable to allocate any listen sockets on port %u",
1187                     listen_port);
1188
1189         drop_privileges(cred);
1190
1191         loginfo("Ready to rumble");
1192
1193         return service_loop(&socklist);
1194 }
1195
1196 int main(int argc, char **argv)
1197 {
1198         int listen_port = 0;
1199         struct string_list listen_addr = STRING_LIST_INIT_NODUP;
1200         int serve_mode = 0, inetd_mode = 0;
1201         const char *pid_file = NULL, *user_name = NULL, *group_name = NULL;
1202         int detach = 0;
1203         struct credentials *cred = NULL;
1204         int i;
1205
1206         git_setup_gettext();
1207
1208         git_extract_argv0_path(argv[0]);
1209
1210         for (i = 1; i < argc; i++) {
1211                 char *arg = argv[i];
1212                 const char *v;
1213
1214                 if (skip_prefix(arg, "--listen=", &v)) {
1215                         string_list_append(&listen_addr, xstrdup_tolower(v));
1216                         continue;
1217                 }
1218                 if (skip_prefix(arg, "--port=", &v)) {
1219                         char *end;
1220                         unsigned long n;
1221                         n = strtoul(v, &end, 0);
1222                         if (*v && !*end) {
1223                                 listen_port = n;
1224                                 continue;
1225                         }
1226                 }
1227                 if (!strcmp(arg, "--serve")) {
1228                         serve_mode = 1;
1229                         continue;
1230                 }
1231                 if (!strcmp(arg, "--inetd")) {
1232                         inetd_mode = 1;
1233                         log_syslog = 1;
1234                         continue;
1235                 }
1236                 if (!strcmp(arg, "--verbose")) {
1237                         verbose = 1;
1238                         continue;
1239                 }
1240                 if (!strcmp(arg, "--syslog")) {
1241                         log_syslog = 1;
1242                         continue;
1243                 }
1244                 if (!strcmp(arg, "--export-all")) {
1245                         export_all_trees = 1;
1246                         continue;
1247                 }
1248                 if (skip_prefix(arg, "--access-hook=", &v)) {
1249                         access_hook = v;
1250                         continue;
1251                 }
1252                 if (skip_prefix(arg, "--timeout=", &v)) {
1253                         timeout = atoi(v);
1254                         continue;
1255                 }
1256                 if (skip_prefix(arg, "--init-timeout=", &v)) {
1257                         init_timeout = atoi(v);
1258                         continue;
1259                 }
1260                 if (skip_prefix(arg, "--max-connections=", &v)) {
1261                         max_connections = atoi(v);
1262                         if (max_connections < 0)
1263                                 max_connections = 0;            /* unlimited */
1264                         continue;
1265                 }
1266                 if (!strcmp(arg, "--strict-paths")) {
1267                         strict_paths = 1;
1268                         continue;
1269                 }
1270                 if (skip_prefix(arg, "--base-path=", &v)) {
1271                         base_path = v;
1272                         continue;
1273                 }
1274                 if (!strcmp(arg, "--base-path-relaxed")) {
1275                         base_path_relaxed = 1;
1276                         continue;
1277                 }
1278                 if (skip_prefix(arg, "--interpolated-path=", &v)) {
1279                         interpolated_path = v;
1280                         continue;
1281                 }
1282                 if (!strcmp(arg, "--reuseaddr")) {
1283                         reuseaddr = 1;
1284                         continue;
1285                 }
1286                 if (!strcmp(arg, "--user-path")) {
1287                         user_path = "";
1288                         continue;
1289                 }
1290                 if (skip_prefix(arg, "--user-path=", &v)) {
1291                         user_path = v;
1292                         continue;
1293                 }
1294                 if (skip_prefix(arg, "--pid-file=", &v)) {
1295                         pid_file = v;
1296                         continue;
1297                 }
1298                 if (!strcmp(arg, "--detach")) {
1299                         detach = 1;
1300                         log_syslog = 1;
1301                         continue;
1302                 }
1303                 if (skip_prefix(arg, "--user=", &v)) {
1304                         user_name = v;
1305                         continue;
1306                 }
1307                 if (skip_prefix(arg, "--group=", &v)) {
1308                         group_name = v;
1309                         continue;
1310                 }
1311                 if (skip_prefix(arg, "--enable=", &v)) {
1312                         enable_service(v, 1);
1313                         continue;
1314                 }
1315                 if (skip_prefix(arg, "--disable=", &v)) {
1316                         enable_service(v, 0);
1317                         continue;
1318                 }
1319                 if (skip_prefix(arg, "--allow-override=", &v)) {
1320                         make_service_overridable(v, 1);
1321                         continue;
1322                 }
1323                 if (skip_prefix(arg, "--forbid-override=", &v)) {
1324                         make_service_overridable(v, 0);
1325                         continue;
1326                 }
1327                 if (!strcmp(arg, "--informative-errors")) {
1328                         informative_errors = 1;
1329                         continue;
1330                 }
1331                 if (!strcmp(arg, "--no-informative-errors")) {
1332                         informative_errors = 0;
1333                         continue;
1334                 }
1335                 if (!strcmp(arg, "--")) {
1336                         ok_paths = &argv[i+1];
1337                         break;
1338                 } else if (arg[0] != '-') {
1339                         ok_paths = &argv[i];
1340                         break;
1341                 }
1342
1343                 usage(daemon_usage);
1344         }
1345
1346         if (log_syslog) {
1347                 openlog("git-daemon", LOG_PID, LOG_DAEMON);
1348                 set_die_routine(daemon_die);
1349         } else
1350                 /* avoid splitting a message in the middle */
1351                 setvbuf(stderr, NULL, _IOFBF, 4096);
1352
1353         if (inetd_mode && (detach || group_name || user_name))
1354                 die("--detach, --user and --group are incompatible with --inetd");
1355
1356         if (inetd_mode && (listen_port || (listen_addr.nr > 0)))
1357                 die("--listen= and --port= are incompatible with --inetd");
1358         else if (listen_port == 0)
1359                 listen_port = DEFAULT_GIT_PORT;
1360
1361         if (group_name && !user_name)
1362                 die("--group supplied without --user");
1363
1364         if (user_name)
1365                 cred = prepare_credentials(user_name, group_name);
1366
1367         if (strict_paths && (!ok_paths || !*ok_paths))
1368                 die("option --strict-paths requires a whitelist");
1369
1370         if (base_path && !is_directory(base_path))
1371                 die("base-path '%s' does not exist or is not a directory",
1372                     base_path);
1373
1374         if (inetd_mode) {
1375                 if (!freopen("/dev/null", "w", stderr))
1376                         die_errno("failed to redirect stderr to /dev/null");
1377         }
1378
1379         if (inetd_mode || serve_mode)
1380                 return execute();
1381
1382         if (detach) {
1383                 if (daemonize())
1384                         die("--detach not supported on this platform");
1385         } else
1386                 sanitize_stdfds();
1387
1388         if (pid_file)
1389                 store_pid(pid_file);
1390
1391         /* prepare argv for serving-processes */
1392         cld_argv = xmalloc(sizeof (char *) * (argc + 2));
1393         cld_argv[0] = argv[0];  /* git-daemon */
1394         cld_argv[1] = "--serve";
1395         for (i = 1; i < argc; ++i)
1396                 cld_argv[i+1] = argv[i];
1397         cld_argv[argc+1] = NULL;
1398
1399         return serve(&listen_addr, listen_port, cred);
1400 }