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

   1 #include "cache.h"
   2 #include "pkt-line.h"
   3 #include "run-command.h"
   4 #include "strbuf.h"
   5 #include "string-list.h"
   6
   7 #ifndef HOST_NAME_MAX
   8 #define HOST_NAME_MAX 256
   9 #endif
  10
  11 #ifdef NO_INITGROUPS
  12 #define initgroups(x, y) (0) /* nothing */
  13 #endif
  14
  15 static int log_syslog;
  16 static int verbose;
  17 static int reuseaddr;
  18 static int informative_errors;
  19
  20 static const char daemon_usage[] =
  21 "git daemon [--verbose] [--syslog] [--export-all]\n"
  22 "           [--timeout=<n>] [--init-timeout=<n>] [--max-connections=<n>]\n"
  23 "           [--strict-paths] [--base-path=<path>] [--base-path-relaxed]\n"
  24 "           [--user-path | --user-path=<path>]\n"
  25 "           [--interpolated-path=<path>]\n"
  26 "           [--reuseaddr] [--pid-file=<file>]\n"
  27 "           [--(enable|disable|allow-override|forbid-override)=<service>]\n"
  28 "           [--access-hook=<path>]\n"
  29 "           [--inetd | [--listen=<host_or_ipaddr>] [--port=<n>]\n"
  30 "                      [--detach] [--user=<user> [--group=<group>]]\n"
  31 "           [<directory>...]";
  32
  33 /* List of acceptable pathname prefixes */
  34 static const char **ok_paths;
  35 static int strict_paths;
  36
  37 /* If this is set, git-daemon-export-ok is not required */
  38 static int export_all_trees;
  39
  40 /* Take all paths relative to this one if non-NULL */
  41 static const char *base_path;
  42 static const char *interpolated_path;
  43 static int base_path_relaxed;
  44
  45 /* If defined, ~user notation is allowed and the string is inserted
  46  * after ~user/.  E.g. a request to git://host/~alice/frotz would
  47  * go to /home/alice/pub_git/frotz with --user-path=pub_git.
  48  */
  49 static const char *user_path;
  50
  51 /* Timeout, and initial timeout */
  52 static unsigned int timeout;
  53 static unsigned int init_timeout;
  54
  55 struct hostinfo {
  56         struct strbuf hostname;
  57         struct strbuf canon_hostname;
  58         struct strbuf ip_address;
  59         struct strbuf tcp_port;
  60         unsigned int hostname_lookup_done:1;
  61         unsigned int saw_extended_args:1;
  62 };
  63
  64 static void lookup_hostname(struct hostinfo *hi);
  65
  66 static const char *get_canon_hostname(struct hostinfo *hi)
  67 {
  68         lookup_hostname(hi);
  69         return hi->canon_hostname.buf;
  70 }
  71
  72 static const char *get_ip_address(struct hostinfo *hi)
  73 {
  74         lookup_hostname(hi);
  75         return hi->ip_address.buf;
  76 }
  77
  78 static void logreport(int priority, const char *err, va_list params)
  79 {
  80         if (log_syslog) {
  81                 char buf[1024];
  82                 vsnprintf(buf, sizeof(buf), err, params);
  83                 syslog(priority, "%s", buf);
  84         } else {
  85                 /*
  86                  * Since stderr is set to buffered mode, the
  87                  * logging of different processes will not overlap
  88                  * unless they overflow the (rather big) buffers.
  89                  */
  90                 fprintf(stderr, "[%"PRIuMAX"] ", (uintmax_t)getpid());
  91                 vfprintf(stderr, err, params);
  92                 fputc('\n', stderr);
  93                 fflush(stderr);
  94         }
  95 }
  96
  97 __attribute__((format (printf, 1, 2)))
  98 static void logerror(const char *err, ...)
  99 {
 100         va_list params;
 101         va_start(params, err);
 102         logreport(LOG_ERR, err, params);
 103         va_end(params);
 104 }
 105
 106 __attribute__((format (printf, 1, 2)))
 107 static void loginfo(const char *err, ...)
 108 {
 109         va_list params;
 110         if (!verbose)
 111                 return;
 112         va_start(params, err);
 113         logreport(LOG_INFO, err, params);
 114         va_end(params);
 115 }
 116
 117 static void NORETURN daemon_die(const char *err, va_list params)
 118 {
 119         logreport(LOG_ERR, err, params);
 120         exit(1);
 121 }
 122
 123 struct expand_path_context {
 124         const char *directory;
 125         struct hostinfo *hostinfo;
 126 };
 127
 128 static size_t expand_path(struct strbuf *sb, const char *placeholder, void *ctx)
 129 {
 130         struct expand_path_context *context = ctx;
 131         struct hostinfo *hi = context->hostinfo;
 132
 133         switch (placeholder[0]) {
 134         case 'H':
 135                 strbuf_addbuf(sb, &hi->hostname);
 136                 return 1;
 137         case 'C':
 138                 if (placeholder[1] == 'H') {
 139                         strbuf_addstr(sb, get_canon_hostname(hi));
 140                         return 2;
 141                 }
 142                 break;
 143         case 'I':
 144                 if (placeholder[1] == 'P') {
 145                         strbuf_addstr(sb, get_ip_address(hi));
 146                         return 2;
 147                 }
 148                 break;
 149         case 'P':
 150                 strbuf_addbuf(sb, &hi->tcp_port);
 151                 return 1;
 152         case 'D':
 153                 strbuf_addstr(sb, context->directory);
 154                 return 1;
 155         }
 156         return 0;
 157 }
 158
 159 static const char *path_ok(const char *directory, struct hostinfo *hi)
 160 {
 161         static char rpath[PATH_MAX];
 162         static char interp_path[PATH_MAX];
 163         const char *path;
 164         const char *dir;
 165
 166         dir = directory;
 167
 168         if (daemon_avoid_alias(dir)) {
 169                 logerror("'%s': aliased", dir);
 170                 return NULL;
 171         }
 172
 173         if (*dir == '~') {
 174                 if (!user_path) {
 175                         logerror("'%s': User-path not allowed", dir);
 176                         return NULL;
 177                 }
 178                 if (*user_path) {
 179                         /* Got either "~alice" or "~alice/foo";
 180                          * rewrite them to "~alice/%s" or
 181                          * "~alice/%s/foo".
 182                          */
 183                         int namlen, restlen = strlen(dir);
 184                         const char *slash = strchr(dir, '/');
 185                         if (!slash)
 186                                 slash = dir + restlen;
 187                         namlen = slash - dir;
 188                         restlen -= namlen;
 189                         loginfo("userpath <%s>, request <%s>, namlen %d, restlen %d, slash <%s>", user_path, dir, namlen, restlen, slash);
 190                         snprintf(rpath, PATH_MAX, "%.*s/%s%.*s",
 191                                  namlen, dir, user_path, restlen, slash);
 192                         dir = rpath;
 193                 }
 194         }
 195         else if (interpolated_path && hi->saw_extended_args) {
 196                 struct strbuf expanded_path = STRBUF_INIT;
 197                 struct expand_path_context context;
 198
 199                 context.directory = directory;
 200                 context.hostinfo = hi;
 201
 202                 if (*dir != '/') {
 203                         /* Allow only absolute */
 204                         logerror("'%s': Non-absolute path denied (interpolated-path active)", dir);
 205                         return NULL;
 206                 }
 207
 208                 strbuf_expand(&expanded_path, interpolated_path,
 209                               expand_path, &context);
 210                 strlcpy(interp_path, expanded_path.buf, PATH_MAX);
 211                 strbuf_release(&expanded_path);
 212                 loginfo("Interpolated dir '%s'", interp_path);
 213
 214                 dir = interp_path;
 215         }
 216         else if (base_path) {
 217                 if (*dir != '/') {
 218                         /* Allow only absolute */
 219                         logerror("'%s': Non-absolute path denied (base-path active)", dir);
 220                         return NULL;
 221                 }
 222                 snprintf(rpath, PATH_MAX, "%s%s", base_path, dir);
 223                 dir = rpath;
 224         }
 225
 226         path = enter_repo(dir, strict_paths);
 227         if (!path && base_path && base_path_relaxed) {
 228                 /*
 229                  * if we fail and base_path_relaxed is enabled, try without
 230                  * prefixing the base path
 231                  */
 232                 dir = directory;
 233                 path = enter_repo(dir, strict_paths);
 234         }
 235
 236         if (!path) {
 237                 logerror("'%s' does not appear to be a git repository", dir);
 238                 return NULL;
 239         }
 240
 241         if ( ok_paths && *ok_paths ) {
 242                 const char **pp;
 243                 int pathlen = strlen(path);
 244
 245                 /* The validation is done on the paths after enter_repo
 246                  * appends optional {.git,.git/.git} and friends, but
 247                  * it does not use getcwd().  So if your /pub is
 248                  * a symlink to /mnt/pub, you can whitelist /pub and
 249                  * do not have to say /mnt/pub.
 250                  * Do not say /pub/.
 251                  */
 252                 for ( pp = ok_paths ; *pp ; pp++ ) {
 253                         int len = strlen(*pp);
 254                         if (len <= pathlen &&
 255                             !memcmp(*pp, path, len) &&
 256                             (path[len] == '\0' ||
 257                              (!strict_paths && path[len] == '/')))
 258                                 return path;
 259                 }
 260         }
 261         else {
 262                 /* be backwards compatible */
 263                 if (!strict_paths)
 264                         return path;
 265         }
 266
 267         logerror("'%s': not in whitelist", path);
 268         return NULL;            /* Fallthrough. Deny by default */
 269 }
 270
 271 typedef int (*daemon_service_fn)(void);
 272 struct daemon_service {
 273         const char *name;
 274         const char *config_name;
 275         daemon_service_fn fn;
 276         int enabled;
 277         int overridable;
 278 };
 279
 280 static int daemon_error(const char *dir, const char *msg)
 281 {
 282         if (!informative_errors)
 283                 msg = "access denied or repository not exported";
 284         packet_write(1, "ERR %s: %s", msg, dir);
 285         return -1;
 286 }
 287
 288 static const char *access_hook;
 289
 290 static int run_access_hook(struct daemon_service *service, const char *dir,
 291                            const char *path, struct hostinfo *hi)
 292 {
 293         struct child_process child = CHILD_PROCESS_INIT;
 294         struct strbuf buf = STRBUF_INIT;
 295         const char *argv[8];
 296         const char **arg = argv;
 297         char *eol;
 298         int seen_errors = 0;
 299
 300         *arg++ = access_hook;
 301         *arg++ = service->name;
 302         *arg++ = path;
 303         *arg++ = hi->hostname.buf;
 304         *arg++ = get_canon_hostname(hi);
 305         *arg++ = get_ip_address(hi);
 306         *arg++ = hi->tcp_port.buf;
 307         *arg = NULL;
 308
 309         child.use_shell = 1;
 310         child.argv = argv;
 311         child.no_stdin = 1;
 312         child.no_stderr = 1;
 313         child.out = -1;
 314         if (start_command(&child)) {
 315                 logerror("daemon access hook '%s' failed to start",
 316                          access_hook);
 317                 goto error_return;
 318         }
 319         if (strbuf_read(&buf, child.out, 0) < 0) {
 320                 logerror("failed to read from pipe to daemon access hook '%s'",
 321                          access_hook);
 322                 strbuf_reset(&buf);
 323                 seen_errors = 1;
 324         }
 325         if (close(child.out) < 0) {
 326                 logerror("failed to close pipe to daemon access hook '%s'",
 327                          access_hook);
 328                 seen_errors = 1;
 329         }
 330         if (finish_command(&child))
 331                 seen_errors = 1;
 332
 333         if (!seen_errors) {
 334                 strbuf_release(&buf);
 335                 return 0;
 336         }
 337
 338 error_return:
 339         strbuf_ltrim(&buf);
 340         if (!buf.len)
 341                 strbuf_addstr(&buf, "service rejected");
 342         eol = strchr(buf.buf, '\n');
 343         if (eol)
 344                 *eol = '\0';
 345         errno = EACCES;
 346         daemon_error(dir, buf.buf);
 347         strbuf_release(&buf);
 348         return -1;
 349 }
 350
 351 static int run_service(const char *dir, struct daemon_service *service,
 352                        struct hostinfo *hi)
 353 {
 354         const char *path;
 355         int enabled = service->enabled;
 356         struct strbuf var = STRBUF_INIT;
 357
 358         loginfo("Request %s for '%s'", service->name, dir);
 359
 360         if (!enabled && !service->overridable) {
 361                 logerror("'%s': service not enabled.", service->name);
 362                 errno = EACCES;
 363                 return daemon_error(dir, "service not enabled");
 364         }
 365
 366         if (!(path = path_ok(dir, hi)))
 367                 return daemon_error(dir, "no such repository");
 368
 369         /*
 370          * Security on the cheap.
 371          *
 372          * We want a readable HEAD, usable "objects" directory, and
 373          * a "git-daemon-export-ok" flag that says that the other side
 374          * is ok with us doing this.
 375          *
 376          * path_ok() uses enter_repo() and does whitelist checking.
 377          * We only need to make sure the repository is exported.
 378          */
 379
 380         if (!export_all_trees && access("git-daemon-export-ok", F_OK)) {
 381                 logerror("'%s': repository not exported.", path);
 382                 errno = EACCES;
 383                 return daemon_error(dir, "repository not exported");
 384         }
 385
 386         if (service->overridable) {
 387                 strbuf_addf(&var, "daemon.%s", service->config_name);
 388                 git_config_get_bool(var.buf, &enabled);
 389                 strbuf_release(&var);
 390         }
 391         if (!enabled) {
 392                 logerror("'%s': service not enabled for '%s'",
 393                          service->name, path);
 394                 errno = EACCES;
 395                 return daemon_error(dir, "service not enabled");
 396         }
 397
 398         /*
 399          * Optionally, a hook can choose to deny access to the
 400          * repository depending on the phase of the moon.
 401          */
 402         if (access_hook && run_access_hook(service, dir, path, hi))
 403                 return -1;
 404
 405         /*
 406          * We'll ignore SIGTERM from now on, we have a
 407          * good client.
 408          */
 409         signal(SIGTERM, SIG_IGN);
 410
 411         return service->fn();
 412 }
 413
 414 static void copy_to_log(int fd)
 415 {
 416         struct strbuf line = STRBUF_INIT;
 417         FILE *fp;
 418
 419         fp = fdopen(fd, "r");
 420         if (fp == NULL) {
 421                 logerror("fdopen of error channel failed");
 422                 close(fd);
 423                 return;
 424         }
 425
 426         while (strbuf_getline_lf(&line, fp) != EOF) {
 427                 logerror("%s", line.buf);
 428                 strbuf_setlen(&line, 0);
 429         }
 430
 431         strbuf_release(&line);
 432         fclose(fp);
 433 }
 434
 435 static int run_service_command(const char **argv)
 436 {
 437         struct child_process cld = CHILD_PROCESS_INIT;
 438
 439         cld.argv = argv;
 440         cld.git_cmd = 1;
 441         cld.err = -1;
 442         if (start_command(&cld))
 443                 return -1;
 444
 445         close(0);
 446         close(1);
 447
 448         copy_to_log(cld.err);
 449
 450         return finish_command(&cld);
 451 }
 452
 453 static int upload_pack(void)
 454 {
 455         /* Timeout as string */
 456         char timeout_buf[64];
 457         const char *argv[] = { "upload-pack", "--strict", NULL, ".", NULL };
 458
 459         argv[2] = timeout_buf;
 460
 461         snprintf(timeout_buf, sizeof timeout_buf, "--timeout=%u", timeout);
 462         return run_service_command(argv);
 463 }
 464
 465 static int upload_archive(void)
 466 {
 467         static const char *argv[] = { "upload-archive", ".", NULL };
 468         return run_service_command(argv);
 469 }
 470
 471 static int receive_pack(void)
 472 {
 473         static const char *argv[] = { "receive-pack", ".", NULL };
 474         return run_service_command(argv);
 475 }
 476
 477 static struct daemon_service daemon_service[] = {
 478         { "upload-archive", "uploadarch", upload_archive, 0, 1 },
 479         { "upload-pack", "uploadpack", upload_pack, 1, 1 },
 480         { "receive-pack", "receivepack", receive_pack, 0, 1 },
 481 };
 482
 483 static void enable_service(const char *name, int ena)
 484 {
 485         int i;
 486         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 487                 if (!strcmp(daemon_service[i].name, name)) {
 488                         daemon_service[i].enabled = ena;
 489                         return;
 490                 }
 491         }
 492         die("No such service %s", name);
 493 }
 494
 495 static void make_service_overridable(const char *name, int ena)
 496 {
 497         int i;
 498         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 499                 if (!strcmp(daemon_service[i].name, name)) {
 500                         daemon_service[i].overridable = ena;
 501                         return;
 502                 }
 503         }
 504         die("No such service %s", name);
 505 }
 506
 507 static void parse_host_and_port(char *hostport, char **host,
 508         char **port)
 509 {
 510         if (*hostport == '[') {
 511                 char *end;
 512
 513                 end = strchr(hostport, ']');
 514                 if (!end)
 515                         die("Invalid request ('[' without ']')");
 516                 *end = '\0';
 517                 *host = hostport + 1;
 518                 if (!end[1])
 519                         *port = NULL;
 520                 else if (end[1] == ':')
 521                         *port = end + 2;
 522                 else
 523                         die("Garbage after end of host part");
 524         } else {
 525                 *host = hostport;
 526                 *port = strrchr(hostport, ':');
 527                 if (*port) {
 528                         **port = '\0';
 529                         ++*port;
 530                 }
 531         }
 532 }
 533
 534 /*
 535  * Sanitize a string from the client so that it's OK to be inserted into a
 536  * filesystem path. Specifically, we disallow slashes, runs of "..", and
 537  * trailing and leading dots, which means that the client cannot escape
 538  * our base path via ".." traversal.
 539  */
 540 static void sanitize_client(struct strbuf *out, const char *in)
 541 {
 542         for (; *in; in++) {
 543                 if (*in == '/')
 544                         continue;
 545                 if (*in == '.' && (!out->len || out->buf[out->len - 1] == '.'))
 546                         continue;
 547                 strbuf_addch(out, *in);
 548         }
 549
 550         while (out->len && out->buf[out->len - 1] == '.')
 551                 strbuf_setlen(out, out->len - 1);
 552 }
 553
 554 /*
 555  * Like sanitize_client, but we also perform any canonicalization
 556  * to make life easier on the admin.
 557  */
 558 static void canonicalize_client(struct strbuf *out, const char *in)
 559 {
 560         sanitize_client(out, in);
 561         strbuf_tolower(out);
 562 }
 563
 564 /*
 565  * Read the host as supplied by the client connection.
 566  */
 567 static void parse_host_arg(struct hostinfo *hi, char *extra_args, int buflen)
 568 {
 569         char *val;
 570         int vallen;
 571         char *end = extra_args + buflen;
 572
 573         if (extra_args < end && *extra_args) {
 574                 hi->saw_extended_args = 1;
 575                 if (strncasecmp("host=", extra_args, 5) == 0) {
 576                         val = extra_args + 5;
 577                         vallen = strlen(val) + 1;
 578                         if (*val) {
 579                                 /* Split <host>:<port> at colon. */
 580                                 char *host;
 581                                 char *port;
 582                                 parse_host_and_port(val, &host, &port);
 583                                 if (port)
 584                                         sanitize_client(&hi->tcp_port, port);
 585                                 canonicalize_client(&hi->hostname, host);
 586                                 hi->hostname_lookup_done = 0;
 587                         }
 588
 589                         /* On to the next one */
 590                         extra_args = val + vallen;
 591                 }
 592                 if (extra_args < end && *extra_args)
 593                         die("Invalid request");
 594         }
 595 }
 596
 597 /*
 598  * Locate canonical hostname and its IP address.
 599  */
 600 static void lookup_hostname(struct hostinfo *hi)
 601 {
 602         if (!hi->hostname_lookup_done && hi->hostname.len) {
 603 #ifndef NO_IPV6
 604                 struct addrinfo hints;
 605                 struct addrinfo *ai;
 606                 int gai;
 607                 static char addrbuf[HOST_NAME_MAX + 1];
 608
 609                 memset(&hints, 0, sizeof(hints));
 610                 hints.ai_flags = AI_CANONNAME;
 611
 612                 gai = getaddrinfo(hi->hostname.buf, NULL, &hints, &ai);
 613                 if (!gai) {
 614                         struct sockaddr_in *sin_addr = (void *)ai->ai_addr;
 615
 616                         inet_ntop(AF_INET, &sin_addr->sin_addr,
 617                                   addrbuf, sizeof(addrbuf));
 618                         strbuf_addstr(&hi->ip_address, addrbuf);
 619
 620                         if (ai->ai_canonname)
 621                                 sanitize_client(&hi->canon_hostname,
 622                                                 ai->ai_canonname);
 623                         else
 624                                 strbuf_addbuf(&hi->canon_hostname,
 625                                               &hi->ip_address);
 626
 627                         freeaddrinfo(ai);
 628                 }
 629 #else
 630                 struct hostent *hent;
 631                 struct sockaddr_in sa;
 632                 char **ap;
 633                 static char addrbuf[HOST_NAME_MAX + 1];
 634
 635                 hent = gethostbyname(hi->hostname.buf);
 636                 if (hent) {
 637                         ap = hent->h_addr_list;
 638                         memset(&sa, 0, sizeof sa);
 639                         sa.sin_family = hent->h_addrtype;
 640                         sa.sin_port = htons(0);
 641                         memcpy(&sa.sin_addr, *ap, hent->h_length);
 642
 643                         inet_ntop(hent->h_addrtype, &sa.sin_addr,
 644                                   addrbuf, sizeof(addrbuf));
 645
 646                         sanitize_client(&hi->canon_hostname, hent->h_name);
 647                         strbuf_addstr(&hi->ip_address, addrbuf);
 648                 }
 649 #endif
 650                 hi->hostname_lookup_done = 1;
 651         }
 652 }
 653
 654 static void hostinfo_init(struct hostinfo *hi)
 655 {
 656         memset(hi, 0, sizeof(*hi));
 657         strbuf_init(&hi->hostname, 0);
 658         strbuf_init(&hi->canon_hostname, 0);
 659         strbuf_init(&hi->ip_address, 0);
 660         strbuf_init(&hi->tcp_port, 0);
 661 }
 662
 663 static void hostinfo_clear(struct hostinfo *hi)
 664 {
 665         strbuf_release(&hi->hostname);
 666         strbuf_release(&hi->canon_hostname);
 667         strbuf_release(&hi->ip_address);
 668         strbuf_release(&hi->tcp_port);
 669 }
 670
 671 static void set_keep_alive(int sockfd)
 672 {
 673         int ka = 1;
 674
 675         if (setsockopt(sockfd, SOL_SOCKET, SO_KEEPALIVE, &ka, sizeof(ka)) < 0) {
 676                 if (errno != ENOTSOCK)
 677                         logerror("unable to set SO_KEEPALIVE on socket: %s",
 678                                 strerror(errno));
 679         }
 680 }
 681
 682 static int execute(void)
 683 {
 684         char *line = packet_buffer;
 685         int pktlen, len, i;
 686         char *addr = getenv("REMOTE_ADDR"), *port = getenv("REMOTE_PORT");
 687         struct hostinfo hi;
 688
 689         hostinfo_init(&hi);
 690
 691         if (addr)
 692                 loginfo("Connection from %s:%s", addr, port);
 693
 694         set_keep_alive(0);
 695         alarm(init_timeout ? init_timeout : timeout);
 696         pktlen = packet_read(0, NULL, NULL, packet_buffer, sizeof(packet_buffer), 0);
 697         alarm(0);
 698
 699         len = strlen(line);
 700         if (pktlen != len)
 701                 loginfo("Extended attributes (%d bytes) exist <%.*s>",
 702                         (int) pktlen - len,
 703                         (int) pktlen - len, line + len + 1);
 704         if (len && line[len-1] == '\n') {
 705                 line[--len] = 0;
 706                 pktlen--;
 707         }
 708
 709         if (len != pktlen)
 710                 parse_host_arg(&hi, line + len + 1, pktlen - len - 1);
 711
 712         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 713                 struct daemon_service *s = &(daemon_service[i]);
 714                 const char *arg;
 715
 716                 if (skip_prefix(line, "git-", &arg) &&
 717                     skip_prefix(arg, s->name, &arg) &&
 718                     *arg++ == ' ') {
 719                         /*
 720                          * Note: The directory here is probably context sensitive,
 721                          * and might depend on the actual service being performed.
 722                          */
 723                         int rc = run_service(arg, s, &hi);
 724                         hostinfo_clear(&hi);
 725                         return rc;
 726                 }
 727         }
 728
 729         hostinfo_clear(&hi);
 730         logerror("Protocol error: '%s'", line);
 731         return -1;
 732 }
 733
 734 static int addrcmp(const struct sockaddr_storage *s1,
 735     const struct sockaddr_storage *s2)
 736 {
 737         const struct sockaddr *sa1 = (const struct sockaddr*) s1;
 738         const struct sockaddr *sa2 = (const struct sockaddr*) s2;
 739
 740         if (sa1->sa_family != sa2->sa_family)
 741                 return sa1->sa_family - sa2->sa_family;
 742         if (sa1->sa_family == AF_INET)
 743                 return memcmp(&((struct sockaddr_in *)s1)->sin_addr,
 744                     &((struct sockaddr_in *)s2)->sin_addr,
 745                     sizeof(struct in_addr));
 746 #ifndef NO_IPV6
 747         if (sa1->sa_family == AF_INET6)
 748                 return memcmp(&((struct sockaddr_in6 *)s1)->sin6_addr,
 749                     &((struct sockaddr_in6 *)s2)->sin6_addr,
 750                     sizeof(struct in6_addr));
 751 #endif
 752         return 0;
 753 }
 754
 755 static int max_connections = 32;
 756
 757 static unsigned int live_children;
 758
 759 static struct child {
 760         struct child *next;
 761         struct child_process cld;
 762         struct sockaddr_storage address;
 763 } *firstborn;
 764
 765 static void add_child(struct child_process *cld, struct sockaddr *addr, socklen_t addrlen)
 766 {
 767         struct child *newborn, **cradle;
 768
 769         newborn = xcalloc(1, sizeof(*newborn));
 770         live_children++;
 771         memcpy(&newborn->cld, cld, sizeof(*cld));
 772         memcpy(&newborn->address, addr, addrlen);
 773         for (cradle = &firstborn; *cradle; cradle = &(*cradle)->next)
 774                 if (!addrcmp(&(*cradle)->address, &newborn->address))
 775                         break;
 776         newborn->next = *cradle;
 777         *cradle = newborn;
 778 }
 779
 780 /*
 781  * This gets called if the number of connections grows
 782  * past "max_connections".
 783  *
 784  * We kill the newest connection from a duplicate IP.
 785  */
 786 static void kill_some_child(void)
 787 {
 788         const struct child *blanket, *next;
 789
 790         if (!(blanket = firstborn))
 791                 return;
 792
 793         for (; (next = blanket->next); blanket = next)
 794                 if (!addrcmp(&blanket->address, &next->address)) {
 795                         kill(blanket->cld.pid, SIGTERM);
 796                         break;
 797                 }
 798 }
 799
 800 static void check_dead_children(void)
 801 {
 802         int status;
 803         pid_t pid;
 804
 805         struct child **cradle, *blanket;
 806         for (cradle = &firstborn; (blanket = *cradle);)
 807                 if ((pid = waitpid(blanket->cld.pid, &status, WNOHANG)) > 1) {
 808                         const char *dead = "";
 809                         if (status)
 810                                 dead = " (with error)";
 811                         loginfo("[%"PRIuMAX"] Disconnected%s", (uintmax_t)pid, dead);
 812
 813                         /* remove the child */
 814                         *cradle = blanket->next;
 815                         live_children--;
 816                         child_process_clear(&blanket->cld);
 817                         free(blanket);
 818                 } else
 819                         cradle = &blanket->next;
 820 }
 821
 822 static struct argv_array cld_argv = ARGV_ARRAY_INIT;
 823 static void handle(int incoming, struct sockaddr *addr, socklen_t addrlen)
 824 {
 825         struct child_process cld = CHILD_PROCESS_INIT;
 826
 827         if (max_connections && live_children >= max_connections) {
 828                 kill_some_child();
 829                 sleep(1);  /* give it some time to die */
 830                 check_dead_children();
 831                 if (live_children >= max_connections) {
 832                         close(incoming);
 833                         logerror("Too many children, dropping connection");
 834                         return;
 835                 }
 836         }
 837
 838         if (addr->sa_family == AF_INET) {
 839                 char buf[128] = "";
 840                 struct sockaddr_in *sin_addr = (void *) addr;
 841                 inet_ntop(addr->sa_family, &sin_addr->sin_addr, buf, sizeof(buf));
 842                 argv_array_pushf(&cld.env_array, "REMOTE_ADDR=%s", buf);
 843                 argv_array_pushf(&cld.env_array, "REMOTE_PORT=%d",
 844                                  ntohs(sin_addr->sin_port));
 845 #ifndef NO_IPV6
 846         } else if (addr->sa_family == AF_INET6) {
 847                 char buf[128] = "";
 848                 struct sockaddr_in6 *sin6_addr = (void *) addr;
 849                 inet_ntop(AF_INET6, &sin6_addr->sin6_addr, buf, sizeof(buf));
 850                 argv_array_pushf(&cld.env_array, "REMOTE_ADDR=[%s]", buf);
 851                 argv_array_pushf(&cld.env_array, "REMOTE_PORT=%d",
 852                                  ntohs(sin6_addr->sin6_port));
 853 #endif
 854         }
 855
 856         cld.argv = cld_argv.argv;
 857         cld.in = incoming;
 858         cld.out = dup(incoming);
 859
 860         if (start_command(&cld))
 861                 logerror("unable to fork");
 862         else
 863                 add_child(&cld, addr, addrlen);
 864 }
 865
 866 static void child_handler(int signo)
 867 {
 868         /*
 869          * Otherwise empty handler because systemcalls will get interrupted
 870          * upon signal receipt
 871          * SysV needs the handler to be rearmed
 872          */
 873         signal(SIGCHLD, child_handler);
 874 }
 875
 876 static int set_reuse_addr(int sockfd)
 877 {
 878         int on = 1;
 879
 880         if (!reuseaddr)
 881                 return 0;
 882         return setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
 883                           &on, sizeof(on));
 884 }
 885
 886 struct socketlist {
 887         int *list;
 888         size_t nr;
 889         size_t alloc;
 890 };
 891
 892 static const char *ip2str(int family, struct sockaddr *sin, socklen_t len)
 893 {
 894 #ifdef NO_IPV6
 895         static char ip[INET_ADDRSTRLEN];
 896 #else
 897         static char ip[INET6_ADDRSTRLEN];
 898 #endif
 899
 900         switch (family) {
 901 #ifndef NO_IPV6
 902         case AF_INET6:
 903                 inet_ntop(family, &((struct sockaddr_in6*)sin)->sin6_addr, ip, len);
 904                 break;
 905 #endif
 906         case AF_INET:
 907                 inet_ntop(family, &((struct sockaddr_in*)sin)->sin_addr, ip, len);
 908                 break;
 909         default:
 910                 xsnprintf(ip, sizeof(ip), "<unknown>");
 911         }
 912         return ip;
 913 }
 914
 915 #ifndef NO_IPV6
 916
 917 static int setup_named_sock(char *listen_addr, int listen_port, struct socketlist *socklist)
 918 {
 919         int socknum = 0;
 920         char pbuf[NI_MAXSERV];
 921         struct addrinfo hints, *ai0, *ai;
 922         int gai;
 923         long flags;
 924
 925         xsnprintf(pbuf, sizeof(pbuf), "%d", listen_port);
 926         memset(&hints, 0, sizeof(hints));
 927         hints.ai_family = AF_UNSPEC;
 928         hints.ai_socktype = SOCK_STREAM;
 929         hints.ai_protocol = IPPROTO_TCP;
 930         hints.ai_flags = AI_PASSIVE;
 931
 932         gai = getaddrinfo(listen_addr, pbuf, &hints, &ai0);
 933         if (gai) {
 934                 logerror("getaddrinfo() for %s failed: %s", listen_addr, gai_strerror(gai));
 935                 return 0;
 936         }
 937
 938         for (ai = ai0; ai; ai = ai->ai_next) {
 939                 int sockfd;
 940
 941                 sockfd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
 942                 if (sockfd < 0)
 943                         continue;
 944                 if (sockfd >= FD_SETSIZE) {
 945                         logerror("Socket descriptor too large");
 946                         close(sockfd);
 947                         continue;
 948                 }
 949
 950 #ifdef IPV6_V6ONLY
 951                 if (ai->ai_family == AF_INET6) {
 952                         int on = 1;
 953                         setsockopt(sockfd, IPPROTO_IPV6, IPV6_V6ONLY,
 954                                    &on, sizeof(on));
 955                         /* Note: error is not fatal */
 956                 }
 957 #endif
 958
 959                 if (set_reuse_addr(sockfd)) {
 960                         logerror("Could not set SO_REUSEADDR: %s", strerror(errno));
 961                         close(sockfd);
 962                         continue;
 963                 }
 964
 965                 set_keep_alive(sockfd);
 966
 967                 if (bind(sockfd, ai->ai_addr, ai->ai_addrlen) < 0) {
 968                         logerror("Could not bind 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                 if (listen(sockfd, 5) < 0) {
 975                         logerror("Could not listen to %s: %s",
 976                                  ip2str(ai->ai_family, ai->ai_addr, ai->ai_addrlen),
 977                                  strerror(errno));
 978                         close(sockfd);
 979                         continue;       /* not fatal */
 980                 }
 981
 982                 flags = fcntl(sockfd, F_GETFD, 0);
 983                 if (flags >= 0)
 984                         fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
 985
 986                 ALLOC_GROW(socklist->list, socklist->nr + 1, socklist->alloc);
 987                 socklist->list[socklist->nr++] = sockfd;
 988                 socknum++;
 989         }
 990
 991         freeaddrinfo(ai0);
 992
 993         return socknum;
 994 }
 995
 996 #else /* NO_IPV6 */
 997
 998 static int setup_named_sock(char *listen_addr, int listen_port, struct socketlist *socklist)
 999 {
1000         struct sockaddr_in sin;
1001         int sockfd;
1002         long flags;
1003
1004         memset(&sin, 0, sizeof sin);
1005         sin.sin_family = AF_INET;
1006         sin.sin_port = htons(listen_port);
1007
1008         if (listen_addr) {
1009                 /* Well, host better be an IP address here. */
1010                 if (inet_pton(AF_INET, listen_addr, &sin.sin_addr.s_addr) <= 0)
1011                         return 0;
1012         } else {
1013                 sin.sin_addr.s_addr = htonl(INADDR_ANY);
1014         }
1015
1016         sockfd = socket(AF_INET, SOCK_STREAM, 0);
1017         if (sockfd < 0)
1018                 return 0;
1019
1020         if (set_reuse_addr(sockfd)) {
1021                 logerror("Could not set SO_REUSEADDR: %s", strerror(errno));
1022                 close(sockfd);
1023                 return 0;
1024         }
1025
1026         set_keep_alive(sockfd);
1027
1028         if ( bind(sockfd, (struct sockaddr *)&sin, sizeof sin) < 0 ) {
1029                 logerror("Could not bind to %s: %s",
1030                          ip2str(AF_INET, (struct sockaddr *)&sin, sizeof(sin)),
1031                          strerror(errno));
1032                 close(sockfd);
1033                 return 0;
1034         }
1035
1036         if (listen(sockfd, 5) < 0) {
1037                 logerror("Could not listen to %s: %s",
1038                          ip2str(AF_INET, (struct sockaddr *)&sin, sizeof(sin)),
1039                          strerror(errno));
1040                 close(sockfd);
1041                 return 0;
1042         }
1043
1044         flags = fcntl(sockfd, F_GETFD, 0);
1045         if (flags >= 0)
1046                 fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
1047
1048         ALLOC_GROW(socklist->list, socklist->nr + 1, socklist->alloc);
1049         socklist->list[socklist->nr++] = sockfd;
1050         return 1;
1051 }
1052
1053 #endif
1054
1055 static void socksetup(struct string_list *listen_addr, int listen_port, struct socketlist *socklist)
1056 {
1057         if (!listen_addr->nr)
1058                 setup_named_sock(NULL, listen_port, socklist);
1059         else {
1060                 int i, socknum;
1061                 for (i = 0; i < listen_addr->nr; i++) {
1062                         socknum = setup_named_sock(listen_addr->items[i].string,
1063                                                    listen_port, socklist);
1064
1065                         if (socknum == 0)
1066                                 logerror("unable to allocate any listen sockets for host %s on port %u",
1067                                          listen_addr->items[i].string, listen_port);
1068                 }
1069         }
1070 }
1071
1072 static int service_loop(struct socketlist *socklist)
1073 {
1074         struct pollfd *pfd;
1075         int i;
1076
1077         pfd = xcalloc(socklist->nr, sizeof(struct pollfd));
1078
1079         for (i = 0; i < socklist->nr; i++) {
1080                 pfd[i].fd = socklist->list[i];
1081                 pfd[i].events = POLLIN;
1082         }
1083
1084         signal(SIGCHLD, child_handler);
1085
1086         for (;;) {
1087                 int i;
1088
1089                 check_dead_children();
1090
1091                 if (poll(pfd, socklist->nr, -1) < 0) {
1092                         if (errno != EINTR) {
1093                                 logerror("Poll failed, resuming: %s",
1094                                       strerror(errno));
1095                                 sleep(1);
1096                         }
1097                         continue;
1098                 }
1099
1100                 for (i = 0; i < socklist->nr; i++) {
1101                         if (pfd[i].revents & POLLIN) {
1102                                 union {
1103                                         struct sockaddr sa;
1104                                         struct sockaddr_in sai;
1105 #ifndef NO_IPV6
1106                                         struct sockaddr_in6 sai6;
1107 #endif
1108                                 } ss;
1109                                 socklen_t sslen = sizeof(ss);
1110                                 int incoming = accept(pfd[i].fd, &ss.sa, &sslen);
1111                                 if (incoming < 0) {
1112                                         switch (errno) {
1113                                         case EAGAIN:
1114                                         case EINTR:
1115                                         case ECONNABORTED:
1116                                                 continue;
1117                                         default:
1118                                                 die_errno("accept returned");
1119                                         }
1120                                 }
1121                                 handle(incoming, &ss.sa, sslen);
1122                         }
1123                 }
1124         }
1125 }
1126
1127 #ifdef NO_POSIX_GOODIES
1128
1129 struct credentials;
1130
1131 static void drop_privileges(struct credentials *cred)
1132 {
1133         /* nothing */
1134 }
1135
1136 static struct credentials *prepare_credentials(const char *user_name,
1137     const char *group_name)
1138 {
1139         die("--user not supported on this platform");
1140 }
1141
1142 #else
1143
1144 struct credentials {
1145         struct passwd *pass;
1146         gid_t gid;
1147 };
1148
1149 static void drop_privileges(struct credentials *cred)
1150 {
1151         if (cred && (initgroups(cred->pass->pw_name, cred->gid) ||
1152             setgid (cred->gid) || setuid(cred->pass->pw_uid)))
1153                 die("cannot drop privileges");
1154 }
1155
1156 static struct credentials *prepare_credentials(const char *user_name,
1157     const char *group_name)
1158 {
1159         static struct credentials c;
1160
1161         c.pass = getpwnam(user_name);
1162         if (!c.pass)
1163                 die("user not found - %s", user_name);
1164
1165         if (!group_name)
1166                 c.gid = c.pass->pw_gid;
1167         else {
1168                 struct group *group = getgrnam(group_name);
1169                 if (!group)
1170                         die("group not found - %s", group_name);
1171
1172                 c.gid = group->gr_gid;
1173         }
1174
1175         return &c;
1176 }
1177 #endif
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 cmd_main(int argc, const 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         for (i = 1; i < argc; i++) {
1207                 const char *arg = argv[i];
1208                 const char *v;
1209
1210                 if (skip_prefix(arg, "--listen=", &v)) {
1211                         string_list_append(&listen_addr, xstrdup_tolower(v));
1212                         continue;
1213                 }
1214                 if (skip_prefix(arg, "--port=", &v)) {
1215                         char *end;
1216                         unsigned long n;
1217                         n = strtoul(v, &end, 0);
1218                         if (*v && !*end) {
1219                                 listen_port = n;
1220                                 continue;
1221                         }
1222                 }
1223                 if (!strcmp(arg, "--serve")) {
1224                         serve_mode = 1;
1225                         continue;
1226                 }
1227                 if (!strcmp(arg, "--inetd")) {
1228                         inetd_mode = 1;
1229                         log_syslog = 1;
1230                         continue;
1231                 }
1232                 if (!strcmp(arg, "--verbose")) {
1233                         verbose = 1;
1234                         continue;
1235                 }
1236                 if (!strcmp(arg, "--syslog")) {
1237                         log_syslog = 1;
1238                         continue;
1239                 }
1240                 if (!strcmp(arg, "--export-all")) {
1241                         export_all_trees = 1;
1242                         continue;
1243                 }
1244                 if (skip_prefix(arg, "--access-hook=", &v)) {
1245                         access_hook = v;
1246                         continue;
1247                 }
1248                 if (skip_prefix(arg, "--timeout=", &v)) {
1249                         timeout = atoi(v);
1250                         continue;
1251                 }
1252                 if (skip_prefix(arg, "--init-timeout=", &v)) {
1253                         init_timeout = atoi(v);
1254                         continue;
1255                 }
1256                 if (skip_prefix(arg, "--max-connections=", &v)) {
1257                         max_connections = atoi(v);
1258                         if (max_connections < 0)
1259                                 max_connections = 0;            /* unlimited */
1260                         continue;
1261                 }
1262                 if (!strcmp(arg, "--strict-paths")) {
1263                         strict_paths = 1;
1264                         continue;
1265                 }
1266                 if (skip_prefix(arg, "--base-path=", &v)) {
1267                         base_path = v;
1268                         continue;
1269                 }
1270                 if (!strcmp(arg, "--base-path-relaxed")) {
1271                         base_path_relaxed = 1;
1272                         continue;
1273                 }
1274                 if (skip_prefix(arg, "--interpolated-path=", &v)) {
1275                         interpolated_path = v;
1276                         continue;
1277                 }
1278                 if (!strcmp(arg, "--reuseaddr")) {
1279                         reuseaddr = 1;
1280                         continue;
1281                 }
1282                 if (!strcmp(arg, "--user-path")) {
1283                         user_path = "";
1284                         continue;
1285                 }
1286                 if (skip_prefix(arg, "--user-path=", &v)) {
1287                         user_path = v;
1288                         continue;
1289                 }
1290                 if (skip_prefix(arg, "--pid-file=", &v)) {
1291                         pid_file = v;
1292                         continue;
1293                 }
1294                 if (!strcmp(arg, "--detach")) {
1295                         detach = 1;
1296                         log_syslog = 1;
1297                         continue;
1298                 }
1299                 if (skip_prefix(arg, "--user=", &v)) {
1300                         user_name = v;
1301                         continue;
1302                 }
1303                 if (skip_prefix(arg, "--group=", &v)) {
1304                         group_name = v;
1305                         continue;
1306                 }
1307                 if (skip_prefix(arg, "--enable=", &v)) {
1308                         enable_service(v, 1);
1309                         continue;
1310                 }
1311                 if (skip_prefix(arg, "--disable=", &v)) {
1312                         enable_service(v, 0);
1313                         continue;
1314                 }
1315                 if (skip_prefix(arg, "--allow-override=", &v)) {
1316                         make_service_overridable(v, 1);
1317                         continue;
1318                 }
1319                 if (skip_prefix(arg, "--forbid-override=", &v)) {
1320                         make_service_overridable(v, 0);
1321                         continue;
1322                 }
1323                 if (!strcmp(arg, "--informative-errors")) {
1324                         informative_errors = 1;
1325                         continue;
1326                 }
1327                 if (!strcmp(arg, "--no-informative-errors")) {
1328                         informative_errors = 0;
1329                         continue;
1330                 }
1331                 if (!strcmp(arg, "--")) {
1332                         ok_paths = &argv[i+1];
1333                         break;
1334                 } else if (arg[0] != '-') {
1335                         ok_paths = &argv[i];
1336                         break;
1337                 }
1338
1339                 usage(daemon_usage);
1340         }
1341
1342         if (log_syslog) {
1343                 openlog("git-daemon", LOG_PID, LOG_DAEMON);
1344                 set_die_routine(daemon_die);
1345         } else
1346                 /* avoid splitting a message in the middle */
1347                 setvbuf(stderr, NULL, _IOFBF, 4096);
1348
1349         if (inetd_mode && (detach || group_name || user_name))
1350                 die("--detach, --user and --group are incompatible with --inetd");
1351
1352         if (inetd_mode && (listen_port || (listen_addr.nr > 0)))
1353                 die("--listen= and --port= are incompatible with --inetd");
1354         else if (listen_port == 0)
1355                 listen_port = DEFAULT_GIT_PORT;
1356
1357         if (group_name && !user_name)
1358                 die("--group supplied without --user");
1359
1360         if (user_name)
1361                 cred = prepare_credentials(user_name, group_name);
1362
1363         if (strict_paths && (!ok_paths || !*ok_paths))
1364                 die("option --strict-paths requires a whitelist");
1365
1366         if (base_path && !is_directory(base_path))
1367                 die("base-path '%s' does not exist or is not a directory",
1368                     base_path);
1369
1370         if (inetd_mode) {
1371                 if (!freopen("/dev/null", "w", stderr))
1372                         die_errno("failed to redirect stderr to /dev/null");
1373         }
1374
1375         if (inetd_mode || serve_mode)
1376                 return execute();
1377
1378         if (detach) {
1379                 if (daemonize())
1380                         die("--detach not supported on this platform");
1381         }
1382
1383         if (pid_file)
1384                 write_file(pid_file, "%"PRIuMAX, (uintmax_t) getpid());
1385
1386         /* prepare argv for serving-processes */
1387         argv_array_push(&cld_argv, argv[0]); /* git-daemon */
1388         argv_array_push(&cld_argv, "--serve");
1389         for (i = 1; i < argc; ++i)
1390                 argv_array_push(&cld_argv, argv[i]);
1391
1392         return serve(&listen_addr, listen_port, cred);
1393 }