daemon.c

   1 #include "cache.h"
   2 #include "pkt-line.h"
   3 #include "exec_cmd.h"
   4 #include "interpolate.h"
   5
   6 #include <syslog.h>
   7
   8 #ifndef HOST_NAME_MAX
   9 #define HOST_NAME_MAX 256
  10 #endif
  11
  12 static int log_syslog;
  13 static int verbose;
  14 static int reuseaddr;
  15
  16 static const char daemon_usage[] =
  17 "git-daemon [--verbose] [--syslog] [--export-all]\n"
  18 "           [--timeout=n] [--init-timeout=n] [--strict-paths]\n"
  19 "           [--base-path=path] [--base-path-relaxed]\n"
  20 "           [--user-path | --user-path=path]\n"
  21 "           [--interpolated-path=path]\n"
  22 "           [--reuseaddr] [--detach] [--pid-file=file]\n"
  23 "           [--[enable|disable|allow-override|forbid-override]=service]\n"
  24 "           [--inetd | [--listen=host_or_ipaddr] [--port=n]\n"
  25 "                      [--user=user [--group=group]]\n"
  26 "           [directory...]";
  27
  28 /* List of acceptable pathname prefixes */
  29 static char **ok_paths;
  30 static int strict_paths;
  31
  32 /* If this is set, git-daemon-export-ok is not required */
  33 static int export_all_trees;
  34
  35 /* Take all paths relative to this one if non-NULL */
  36 static char *base_path;
  37 static char *interpolated_path;
  38 static int base_path_relaxed;
  39
  40 /* Flag indicating client sent extra args. */
  41 static int saw_extended_args;
  42
  43 /* If defined, ~user notation is allowed and the string is inserted
  44  * after ~user/.  E.g. a request to git://host/~alice/frotz would
  45  * go to /home/alice/pub_git/frotz with --user-path=pub_git.
  46  */
  47 static const char *user_path;
  48
  49 /* Timeout, and initial timeout */
  50 static unsigned int timeout;
  51 static unsigned int init_timeout;
  52
  53 /*
  54  * Static table for now.  Ugh.
  55  * Feel free to make dynamic as needed.
  56  */
  57 #define INTERP_SLOT_HOST        (0)
  58 #define INTERP_SLOT_CANON_HOST  (1)
  59 #define INTERP_SLOT_IP          (2)
  60 #define INTERP_SLOT_PORT        (3)
  61 #define INTERP_SLOT_DIR         (4)
  62 #define INTERP_SLOT_PERCENT     (5)
  63
  64 static struct interp interp_table[] = {
  65         { "%H", 0},
  66         { "%CH", 0},
  67         { "%IP", 0},
  68         { "%P", 0},
  69         { "%D", 0},
  70         { "%%", 0},
  71 };
  72
  73
  74 static void logreport(int priority, const char *err, va_list params)
  75 {
  76         /* We should do a single write so that it is atomic and output
  77          * of several processes do not get intermingled. */
  78         char buf[1024];
  79         int buflen;
  80         int maxlen, msglen;
  81
  82         /* sizeof(buf) should be big enough for "[pid] \n" */
  83         buflen = snprintf(buf, sizeof(buf), "[%ld] ", (long) getpid());
  84
  85         maxlen = sizeof(buf) - buflen - 1; /* -1 for our own LF */
  86         msglen = vsnprintf(buf + buflen, maxlen, err, params);
  87
  88         if (log_syslog) {
  89                 syslog(priority, "%s", buf);
  90                 return;
  91         }
  92
  93         /* maxlen counted our own LF but also counts space given to
  94          * vsnprintf for the terminating NUL.  We want to make sure that
  95          * we have space for our own LF and NUL after the "meat" of the
  96          * message, so truncate it at maxlen - 1.
  97          */
  98         if (msglen > maxlen - 1)
  99                 msglen = maxlen - 1;
 100         else if (msglen < 0)
 101                 msglen = 0; /* Protect against weird return values. */
 102         buflen += msglen;
 103
 104         buf[buflen++] = '\n';
 105         buf[buflen] = '\0';
 106
 107         write_in_full(2, buf, buflen);
 108 }
 109
 110 static void logerror(const char *err, ...)
 111 {
 112         va_list params;
 113         va_start(params, err);
 114         logreport(LOG_ERR, err, params);
 115         va_end(params);
 116 }
 117
 118 static void loginfo(const char *err, ...)
 119 {
 120         va_list params;
 121         if (!verbose)
 122                 return;
 123         va_start(params, err);
 124         logreport(LOG_INFO, err, params);
 125         va_end(params);
 126 }
 127
 128 static void NORETURN daemon_die(const char *err, va_list params)
 129 {
 130         logreport(LOG_ERR, err, params);
 131         exit(1);
 132 }
 133
 134 static int avoid_alias(char *p)
 135 {
 136         int sl, ndot;
 137
 138         /*
 139          * This resurrects the belts and suspenders paranoia check by HPA
 140          * done in <435560F7.4080006@zytor.com> thread, now enter_repo()
 141          * does not do getcwd() based path canonicalizations.
 142          *
 143          * sl becomes true immediately after seeing '/' and continues to
 144          * be true as long as dots continue after that without intervening
 145          * non-dot character.
 146          */
 147         if (!p || (*p != '/' && *p != '~'))
 148                 return -1;
 149         sl = 1; ndot = 0;
 150         p++;
 151
 152         while (1) {
 153                 char ch = *p++;
 154                 if (sl) {
 155                         if (ch == '.')
 156                                 ndot++;
 157                         else if (ch == '/') {
 158                                 if (ndot < 3)
 159                                         /* reject //, /./ and /../ */
 160                                         return -1;
 161                                 ndot = 0;
 162                         }
 163                         else if (ch == 0) {
 164                                 if (0 < ndot && ndot < 3)
 165                                         /* reject /.$ and /..$ */
 166                                         return -1;
 167                                 return 0;
 168                         }
 169                         else
 170                                 sl = ndot = 0;
 171                 }
 172                 else if (ch == 0)
 173                         return 0;
 174                 else if (ch == '/') {
 175                         sl = 1;
 176                         ndot = 0;
 177                 }
 178         }
 179 }
 180
 181 static char *path_ok(struct interp *itable)
 182 {
 183         static char rpath[PATH_MAX];
 184         static char interp_path[PATH_MAX];
 185         int retried_path = 0;
 186         char *path;
 187         char *dir;
 188
 189         dir = itable[INTERP_SLOT_DIR].value;
 190
 191         if (avoid_alias(dir)) {
 192                 logerror("'%s': aliased", dir);
 193                 return NULL;
 194         }
 195
 196         if (*dir == '~') {
 197                 if (!user_path) {
 198                         logerror("'%s': User-path not allowed", dir);
 199                         return NULL;
 200                 }
 201                 if (*user_path) {
 202                         /* Got either "~alice" or "~alice/foo";
 203                          * rewrite them to "~alice/%s" or
 204                          * "~alice/%s/foo".
 205                          */
 206                         int namlen, restlen = strlen(dir);
 207                         char *slash = strchr(dir, '/');
 208                         if (!slash)
 209                                 slash = dir + restlen;
 210                         namlen = slash - dir;
 211                         restlen -= namlen;
 212                         loginfo("userpath <%s>, request <%s>, namlen %d, restlen %d, slash <%s>", user_path, dir, namlen, restlen, slash);
 213                         snprintf(rpath, PATH_MAX, "%.*s/%s%.*s",
 214                                  namlen, dir, user_path, restlen, slash);
 215                         dir = rpath;
 216                 }
 217         }
 218         else if (interpolated_path && saw_extended_args) {
 219                 if (*dir != '/') {
 220                         /* Allow only absolute */
 221                         logerror("'%s': Non-absolute path denied (interpolated-path active)", dir);
 222                         return NULL;
 223                 }
 224
 225                 interpolate(interp_path, PATH_MAX, interpolated_path,
 226                             interp_table, ARRAY_SIZE(interp_table));
 227                 loginfo("Interpolated dir '%s'", interp_path);
 228
 229                 dir = interp_path;
 230         }
 231         else if (base_path) {
 232                 if (*dir != '/') {
 233                         /* Allow only absolute */
 234                         logerror("'%s': Non-absolute path denied (base-path active)", dir);
 235                         return NULL;
 236                 }
 237                 snprintf(rpath, PATH_MAX, "%s%s", base_path, dir);
 238                 dir = rpath;
 239         }
 240
 241         do {
 242                 path = enter_repo(dir, strict_paths);
 243                 if (path)
 244                         break;
 245
 246                 /*
 247                  * if we fail and base_path_relaxed is enabled, try without
 248                  * prefixing the base path
 249                  */
 250                 if (base_path && base_path_relaxed && !retried_path) {
 251                         dir = itable[INTERP_SLOT_DIR].value;
 252                         retried_path = 1;
 253                         continue;
 254                 }
 255                 break;
 256         } while (1);
 257
 258         if (!path) {
 259                 logerror("'%s': unable to chdir or not a git archive", dir);
 260                 return NULL;
 261         }
 262
 263         if ( ok_paths && *ok_paths ) {
 264                 char **pp;
 265                 int pathlen = strlen(path);
 266
 267                 /* The validation is done on the paths after enter_repo
 268                  * appends optional {.git,.git/.git} and friends, but
 269                  * it does not use getcwd().  So if your /pub is
 270                  * a symlink to /mnt/pub, you can whitelist /pub and
 271                  * do not have to say /mnt/pub.
 272                  * Do not say /pub/.
 273                  */
 274                 for ( pp = ok_paths ; *pp ; pp++ ) {
 275                         int len = strlen(*pp);
 276                         if (len <= pathlen &&
 277                             !memcmp(*pp, path, len) &&
 278                             (path[len] == '\0' ||
 279                              (!strict_paths && path[len] == '/')))
 280                                 return path;
 281                 }
 282         }
 283         else {
 284                 /* be backwards compatible */
 285                 if (!strict_paths)
 286                         return path;
 287         }
 288
 289         logerror("'%s': not in whitelist", path);
 290         return NULL;            /* Fallthrough. Deny by default */
 291 }
 292
 293 typedef int (*daemon_service_fn)(void);
 294 struct daemon_service {
 295         const char *name;
 296         const char *config_name;
 297         daemon_service_fn fn;
 298         int enabled;
 299         int overridable;
 300 };
 301
 302 static struct daemon_service *service_looking_at;
 303 static int service_enabled;
 304
 305 static int git_daemon_config(const char *var, const char *value)
 306 {
 307         if (!prefixcmp(var, "daemon.") &&
 308             !strcmp(var + 7, service_looking_at->config_name)) {
 309                 service_enabled = git_config_bool(var, value);
 310                 return 0;
 311         }
 312
 313         /* we are not interested in parsing any other configuration here */
 314         return 0;
 315 }
 316
 317 static int run_service(struct interp *itable, struct daemon_service *service)
 318 {
 319         const char *path;
 320         int enabled = service->enabled;
 321
 322         loginfo("Request %s for '%s'",
 323                 service->name,
 324                 itable[INTERP_SLOT_DIR].value);
 325
 326         if (!enabled && !service->overridable) {
 327                 logerror("'%s': service not enabled.", service->name);
 328                 errno = EACCES;
 329                 return -1;
 330         }
 331
 332         if (!(path = path_ok(itable)))
 333                 return -1;
 334
 335         /*
 336          * Security on the cheap.
 337          *
 338          * We want a readable HEAD, usable "objects" directory, and
 339          * a "git-daemon-export-ok" flag that says that the other side
 340          * is ok with us doing this.
 341          *
 342          * path_ok() uses enter_repo() and does whitelist checking.
 343          * We only need to make sure the repository is exported.
 344          */
 345
 346         if (!export_all_trees && access("git-daemon-export-ok", F_OK)) {
 347                 logerror("'%s': repository not exported.", path);
 348                 errno = EACCES;
 349                 return -1;
 350         }
 351
 352         if (service->overridable) {
 353                 service_looking_at = service;
 354                 service_enabled = -1;
 355                 git_config(git_daemon_config);
 356                 if (0 <= service_enabled)
 357                         enabled = service_enabled;
 358         }
 359         if (!enabled) {
 360                 logerror("'%s': service not enabled for '%s'",
 361                          service->name, path);
 362                 errno = EACCES;
 363                 return -1;
 364         }
 365
 366         /*
 367          * We'll ignore SIGTERM from now on, we have a
 368          * good client.
 369          */
 370         signal(SIGTERM, SIG_IGN);
 371
 372         return service->fn();
 373 }
 374
 375 static int upload_pack(void)
 376 {
 377         /* Timeout as string */
 378         char timeout_buf[64];
 379
 380         snprintf(timeout_buf, sizeof timeout_buf, "--timeout=%u", timeout);
 381
 382         /* git-upload-pack only ever reads stuff, so this is safe */
 383         execl_git_cmd("upload-pack", "--strict", timeout_buf, ".", NULL);
 384         return -1;
 385 }
 386
 387 static int upload_archive(void)
 388 {
 389         execl_git_cmd("upload-archive", ".", NULL);
 390         return -1;
 391 }
 392
 393 static int receive_pack(void)
 394 {
 395         execl_git_cmd("receive-pack", ".", NULL);
 396         return -1;
 397 }
 398
 399 static struct daemon_service daemon_service[] = {
 400         { "upload-archive", "uploadarch", upload_archive, 0, 1 },
 401         { "upload-pack", "uploadpack", upload_pack, 1, 1 },
 402         { "receive-pack", "receivepack", receive_pack, 0, 1 },
 403 };
 404
 405 static void enable_service(const char *name, int ena) {
 406         int i;
 407         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 408                 if (!strcmp(daemon_service[i].name, name)) {
 409                         daemon_service[i].enabled = ena;
 410                         return;
 411                 }
 412         }
 413         die("No such service %s", name);
 414 }
 415
 416 static void make_service_overridable(const char *name, int ena) {
 417         int i;
 418         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 419                 if (!strcmp(daemon_service[i].name, name)) {
 420                         daemon_service[i].overridable = ena;
 421                         return;
 422                 }
 423         }
 424         die("No such service %s", name);
 425 }
 426
 427 /*
 428  * Separate the "extra args" information as supplied by the client connection.
 429  * Any resulting data is squirreled away in the given interpolation table.
 430  */
 431 static void parse_extra_args(struct interp *table, char *extra_args, int buflen)
 432 {
 433         char *val;
 434         int vallen;
 435         char *end = extra_args + buflen;
 436
 437         while (extra_args < end && *extra_args) {
 438                 saw_extended_args = 1;
 439                 if (strncasecmp("host=", extra_args, 5) == 0) {
 440                         val = extra_args + 5;
 441                         vallen = strlen(val) + 1;
 442                         if (*val) {
 443                                 /* Split <host>:<port> at colon. */
 444                                 char *host = val;
 445                                 char *port = strrchr(host, ':');
 446                                 if (port) {
 447                                         *port = 0;
 448                                         port++;
 449                                         interp_set_entry(table, INTERP_SLOT_PORT, port);
 450                                 }
 451                                 interp_set_entry(table, INTERP_SLOT_HOST, host);
 452                         }
 453
 454                         /* On to the next one */
 455                         extra_args = val + vallen;
 456                 }
 457         }
 458 }
 459
 460 static void fill_in_extra_table_entries(struct interp *itable)
 461 {
 462         char *hp;
 463
 464         /*
 465          * Replace literal host with lowercase-ized hostname.
 466          */
 467         hp = interp_table[INTERP_SLOT_HOST].value;
 468         if (!hp)
 469                 return;
 470         for ( ; *hp; hp++)
 471                 *hp = tolower(*hp);
 472
 473         /*
 474          * Locate canonical hostname and its IP address.
 475          */
 476 #ifndef NO_IPV6
 477         {
 478                 struct addrinfo hints;
 479                 struct addrinfo *ai, *ai0;
 480                 int gai;
 481                 static char addrbuf[HOST_NAME_MAX + 1];
 482
 483                 memset(&hints, 0, sizeof(hints));
 484                 hints.ai_flags = AI_CANONNAME;
 485
 486                 gai = getaddrinfo(interp_table[INTERP_SLOT_HOST].value, 0, &hints, &ai0);
 487                 if (!gai) {
 488                         for (ai = ai0; ai; ai = ai->ai_next) {
 489                                 struct sockaddr_in *sin_addr = (void *)ai->ai_addr;
 490
 491                                 inet_ntop(AF_INET, &sin_addr->sin_addr,
 492                                           addrbuf, sizeof(addrbuf));
 493                                 interp_set_entry(interp_table,
 494                                                  INTERP_SLOT_CANON_HOST, ai->ai_canonname);
 495                                 interp_set_entry(interp_table,
 496                                                  INTERP_SLOT_IP, addrbuf);
 497                                 break;
 498                         }
 499                         freeaddrinfo(ai0);
 500                 }
 501         }
 502 #else
 503         {
 504                 struct hostent *hent;
 505                 struct sockaddr_in sa;
 506                 char **ap;
 507                 static char addrbuf[HOST_NAME_MAX + 1];
 508
 509                 hent = gethostbyname(interp_table[INTERP_SLOT_HOST].value);
 510
 511                 ap = hent->h_addr_list;
 512                 memset(&sa, 0, sizeof sa);
 513                 sa.sin_family = hent->h_addrtype;
 514                 sa.sin_port = htons(0);
 515                 memcpy(&sa.sin_addr, *ap, hent->h_length);
 516
 517                 inet_ntop(hent->h_addrtype, &sa.sin_addr,
 518                           addrbuf, sizeof(addrbuf));
 519
 520                 interp_set_entry(interp_table, INTERP_SLOT_CANON_HOST, hent->h_name);
 521                 interp_set_entry(interp_table, INTERP_SLOT_IP, addrbuf);
 522         }
 523 #endif
 524 }
 525
 526
 527 static int execute(struct sockaddr *addr)
 528 {
 529         static char line[1000];
 530         int pktlen, len, i;
 531
 532         if (addr) {
 533                 char addrbuf[256] = "";
 534                 int port = -1;
 535
 536                 if (addr->sa_family == AF_INET) {
 537                         struct sockaddr_in *sin_addr = (void *) addr;
 538                         inet_ntop(addr->sa_family, &sin_addr->sin_addr, addrbuf, sizeof(addrbuf));
 539                         port = sin_addr->sin_port;
 540 #ifndef NO_IPV6
 541                 } else if (addr && addr->sa_family == AF_INET6) {
 542                         struct sockaddr_in6 *sin6_addr = (void *) addr;
 543
 544                         char *buf = addrbuf;
 545                         *buf++ = '['; *buf = '\0'; /* stpcpy() is cool */
 546                         inet_ntop(AF_INET6, &sin6_addr->sin6_addr, buf, sizeof(addrbuf) - 1);
 547                         strcat(buf, "]");
 548
 549                         port = sin6_addr->sin6_port;
 550 #endif
 551                 }
 552                 loginfo("Connection from %s:%d", addrbuf, port);
 553         }
 554
 555         alarm(init_timeout ? init_timeout : timeout);
 556         pktlen = packet_read_line(0, line, sizeof(line));
 557         alarm(0);
 558
 559         len = strlen(line);
 560         if (pktlen != len)
 561                 loginfo("Extended attributes (%d bytes) exist <%.*s>",
 562                         (int) pktlen - len,
 563                         (int) pktlen - len, line + len + 1);
 564         if (len && line[len-1] == '\n') {
 565                 line[--len] = 0;
 566                 pktlen--;
 567         }
 568
 569         /*
 570          * Initialize the path interpolation table for this connection.
 571          */
 572         interp_clear_table(interp_table, ARRAY_SIZE(interp_table));
 573         interp_set_entry(interp_table, INTERP_SLOT_PERCENT, "%");
 574
 575         if (len != pktlen) {
 576             parse_extra_args(interp_table, line + len + 1, pktlen - len - 1);
 577             fill_in_extra_table_entries(interp_table);
 578         }
 579
 580         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 581                 struct daemon_service *s = &(daemon_service[i]);
 582                 int namelen = strlen(s->name);
 583                 if (!prefixcmp(line, "git-") &&
 584                     !strncmp(s->name, line + 4, namelen) &&
 585                     line[namelen + 4] == ' ') {
 586                         /*
 587                          * Note: The directory here is probably context sensitive,
 588                          * and might depend on the actual service being performed.
 589                          */
 590                         interp_set_entry(interp_table,
 591                                          INTERP_SLOT_DIR, line + namelen + 5);
 592                         return run_service(interp_table, s);
 593                 }
 594         }
 595
 596         logerror("Protocol error: '%s'", line);
 597         return -1;
 598 }
 599
 600
 601 /*
 602  * We count spawned/reaped separately, just to avoid any
 603  * races when updating them from signals. The SIGCHLD handler
 604  * will only update children_reaped, and the fork logic will
 605  * only update children_spawned.
 606  *
 607  * MAX_CHILDREN should be a power-of-two to make the modulus
 608  * operation cheap. It should also be at least twice
 609  * the maximum number of connections we will ever allow.
 610  */
 611 #define MAX_CHILDREN 128
 612
 613 static int max_connections = 25;
 614
 615 /* These are updated by the signal handler */
 616 static volatile unsigned int children_reaped;
 617 static pid_t dead_child[MAX_CHILDREN];
 618
 619 /* These are updated by the main loop */
 620 static unsigned int children_spawned;
 621 static unsigned int children_deleted;
 622
 623 static struct child {
 624         pid_t pid;
 625         int addrlen;
 626         struct sockaddr_storage address;
 627 } live_child[MAX_CHILDREN];
 628
 629 static void add_child(int idx, pid_t pid, struct sockaddr *addr, int addrlen)
 630 {
 631         live_child[idx].pid = pid;
 632         live_child[idx].addrlen = addrlen;
 633         memcpy(&live_child[idx].address, addr, addrlen);
 634 }
 635
 636 /*
 637  * Walk from "deleted" to "spawned", and remove child "pid".
 638  *
 639  * We move everything up by one, since the new "deleted" will
 640  * be one higher.
 641  */
 642 static void remove_child(pid_t pid, unsigned deleted, unsigned spawned)
 643 {
 644         struct child n;
 645
 646         deleted %= MAX_CHILDREN;
 647         spawned %= MAX_CHILDREN;
 648         if (live_child[deleted].pid == pid) {
 649                 live_child[deleted].pid = -1;
 650                 return;
 651         }
 652         n = live_child[deleted];
 653         for (;;) {
 654                 struct child m;
 655                 deleted = (deleted + 1) % MAX_CHILDREN;
 656                 if (deleted == spawned)
 657                         die("could not find dead child %d\n", pid);
 658                 m = live_child[deleted];
 659                 live_child[deleted] = n;
 660                 if (m.pid == pid)
 661                         return;
 662                 n = m;
 663         }
 664 }
 665
 666 /*
 667  * This gets called if the number of connections grows
 668  * past "max_connections".
 669  *
 670  * We _should_ start off by searching for connections
 671  * from the same IP, and if there is some address wth
 672  * multiple connections, we should kill that first.
 673  *
 674  * As it is, we just "randomly" kill 25% of the connections,
 675  * and our pseudo-random generator sucks too. I have no
 676  * shame.
 677  *
 678  * Really, this is just a place-holder for a _real_ algorithm.
 679  */
 680 static void kill_some_children(int signo, unsigned start, unsigned stop)
 681 {
 682         start %= MAX_CHILDREN;
 683         stop %= MAX_CHILDREN;
 684         while (start != stop) {
 685                 if (!(start & 3))
 686                         kill(live_child[start].pid, signo);
 687                 start = (start + 1) % MAX_CHILDREN;
 688         }
 689 }
 690
 691 static void check_max_connections(void)
 692 {
 693         for (;;) {
 694                 int active;
 695                 unsigned spawned, reaped, deleted;
 696
 697                 spawned = children_spawned;
 698                 reaped = children_reaped;
 699                 deleted = children_deleted;
 700
 701                 while (deleted < reaped) {
 702                         pid_t pid = dead_child[deleted % MAX_CHILDREN];
 703                         remove_child(pid, deleted, spawned);
 704                         deleted++;
 705                 }
 706                 children_deleted = deleted;
 707
 708                 active = spawned - deleted;
 709                 if (active <= max_connections)
 710                         break;
 711
 712                 /* Kill some unstarted connections with SIGTERM */
 713                 kill_some_children(SIGTERM, deleted, spawned);
 714                 if (active <= max_connections << 1)
 715                         break;
 716
 717                 /* If the SIGTERM thing isn't helping use SIGKILL */
 718                 kill_some_children(SIGKILL, deleted, spawned);
 719                 sleep(1);
 720         }
 721 }
 722
 723 static void handle(int incoming, struct sockaddr *addr, int addrlen)
 724 {
 725         pid_t pid = fork();
 726
 727         if (pid) {
 728                 unsigned idx;
 729
 730                 close(incoming);
 731                 if (pid < 0)
 732                         return;
 733
 734                 idx = children_spawned % MAX_CHILDREN;
 735                 children_spawned++;
 736                 add_child(idx, pid, addr, addrlen);
 737
 738                 check_max_connections();
 739                 return;
 740         }
 741
 742         dup2(incoming, 0);
 743         dup2(incoming, 1);
 744         close(incoming);
 745
 746         exit(execute(addr));
 747 }
 748
 749 static void child_handler(int signo)
 750 {
 751         for (;;) {
 752                 int status;
 753                 pid_t pid = waitpid(-1, &status, WNOHANG);
 754
 755                 if (pid > 0) {
 756                         unsigned reaped = children_reaped;
 757                         dead_child[reaped % MAX_CHILDREN] = pid;
 758                         children_reaped = reaped + 1;
 759                         /* XXX: Custom logging, since we don't wanna getpid() */
 760                         if (verbose) {
 761                                 const char *dead = "";
 762                                 if (!WIFEXITED(status) || WEXITSTATUS(status) > 0)
 763                                         dead = " (with error)";
 764                                 if (log_syslog)
 765                                         syslog(LOG_INFO, "[%d] Disconnected%s", pid, dead);
 766                                 else
 767                                         fprintf(stderr, "[%d] Disconnected%s\n", pid, dead);
 768                         }
 769                         continue;
 770                 }
 771                 break;
 772         }
 773 }
 774
 775 static int set_reuse_addr(int sockfd)
 776 {
 777         int on = 1;
 778
 779         if (!reuseaddr)
 780                 return 0;
 781         return setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
 782                           &on, sizeof(on));
 783 }
 784
 785 #ifndef NO_IPV6
 786
 787 static int socksetup(char *listen_addr, int listen_port, int **socklist_p)
 788 {
 789         int socknum = 0, *socklist = NULL;
 790         int maxfd = -1;
 791         char pbuf[NI_MAXSERV];
 792         struct addrinfo hints, *ai0, *ai;
 793         int gai;
 794         long flags;
 795
 796         sprintf(pbuf, "%d", listen_port);
 797         memset(&hints, 0, sizeof(hints));
 798         hints.ai_family = AF_UNSPEC;
 799         hints.ai_socktype = SOCK_STREAM;
 800         hints.ai_protocol = IPPROTO_TCP;
 801         hints.ai_flags = AI_PASSIVE;
 802
 803         gai = getaddrinfo(listen_addr, pbuf, &hints, &ai0);
 804         if (gai)
 805                 die("getaddrinfo() failed: %s\n", gai_strerror(gai));
 806
 807         for (ai = ai0; ai; ai = ai->ai_next) {
 808                 int sockfd;
 809
 810                 sockfd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
 811                 if (sockfd < 0)
 812                         continue;
 813                 if (sockfd >= FD_SETSIZE) {
 814                         error("too large socket descriptor.");
 815                         close(sockfd);
 816                         continue;
 817                 }
 818
 819 #ifdef IPV6_V6ONLY
 820                 if (ai->ai_family == AF_INET6) {
 821                         int on = 1;
 822                         setsockopt(sockfd, IPPROTO_IPV6, IPV6_V6ONLY,
 823                                    &on, sizeof(on));
 824                         /* Note: error is not fatal */
 825                 }
 826 #endif
 827
 828                 if (set_reuse_addr(sockfd)) {
 829                         close(sockfd);
 830                         continue;
 831                 }
 832
 833                 if (bind(sockfd, ai->ai_addr, ai->ai_addrlen) < 0) {
 834                         close(sockfd);
 835                         continue;       /* not fatal */
 836                 }
 837                 if (listen(sockfd, 5) < 0) {
 838                         close(sockfd);
 839                         continue;       /* not fatal */
 840                 }
 841
 842                 flags = fcntl(sockfd, F_GETFD, 0);
 843                 if (flags >= 0)
 844                         fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
 845
 846                 socklist = xrealloc(socklist, sizeof(int) * (socknum + 1));
 847                 socklist[socknum++] = sockfd;
 848
 849                 if (maxfd < sockfd)
 850                         maxfd = sockfd;
 851         }
 852
 853         freeaddrinfo(ai0);
 854
 855         *socklist_p = socklist;
 856         return socknum;
 857 }
 858
 859 #else /* NO_IPV6 */
 860
 861 static int socksetup(char *listen_addr, int listen_port, int **socklist_p)
 862 {
 863         struct sockaddr_in sin;
 864         int sockfd;
 865         long flags;
 866
 867         memset(&sin, 0, sizeof sin);
 868         sin.sin_family = AF_INET;
 869         sin.sin_port = htons(listen_port);
 870
 871         if (listen_addr) {
 872                 /* Well, host better be an IP address here. */
 873                 if (inet_pton(AF_INET, listen_addr, &sin.sin_addr.s_addr) <= 0)
 874                         return 0;
 875         } else {
 876                 sin.sin_addr.s_addr = htonl(INADDR_ANY);
 877         }
 878
 879         sockfd = socket(AF_INET, SOCK_STREAM, 0);
 880         if (sockfd < 0)
 881                 return 0;
 882
 883         if (set_reuse_addr(sockfd)) {
 884                 close(sockfd);
 885                 return 0;
 886         }
 887
 888         if ( bind(sockfd, (struct sockaddr *)&sin, sizeof sin) < 0 ) {
 889                 close(sockfd);
 890                 return 0;
 891         }
 892
 893         if (listen(sockfd, 5) < 0) {
 894                 close(sockfd);
 895                 return 0;
 896         }
 897
 898         flags = fcntl(sockfd, F_GETFD, 0);
 899         if (flags >= 0)
 900                 fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
 901
 902         *socklist_p = xmalloc(sizeof(int));
 903         **socklist_p = sockfd;
 904         return 1;
 905 }
 906
 907 #endif
 908
 909 static int service_loop(int socknum, int *socklist)
 910 {
 911         struct pollfd *pfd;
 912         int i;
 913
 914         pfd = xcalloc(socknum, sizeof(struct pollfd));
 915
 916         for (i = 0; i < socknum; i++) {
 917                 pfd[i].fd = socklist[i];
 918                 pfd[i].events = POLLIN;
 919         }
 920
 921         signal(SIGCHLD, child_handler);
 922
 923         for (;;) {
 924                 int i;
 925
 926                 if (poll(pfd, socknum, -1) < 0) {
 927                         if (errno != EINTR) {
 928                                 error("poll failed, resuming: %s",
 929                                       strerror(errno));
 930                                 sleep(1);
 931                         }
 932                         continue;
 933                 }
 934
 935                 for (i = 0; i < socknum; i++) {
 936                         if (pfd[i].revents & POLLIN) {
 937                                 struct sockaddr_storage ss;
 938                                 unsigned int sslen = sizeof(ss);
 939                                 int incoming = accept(pfd[i].fd, (struct sockaddr *)&ss, &sslen);
 940                                 if (incoming < 0) {
 941                                         switch (errno) {
 942                                         case EAGAIN:
 943                                         case EINTR:
 944                                         case ECONNABORTED:
 945                                                 continue;
 946                                         default:
 947                                                 die("accept returned %s", strerror(errno));
 948                                         }
 949                                 }
 950                                 handle(incoming, (struct sockaddr *)&ss, sslen);
 951                         }
 952                 }
 953         }
 954 }
 955
 956 /* if any standard file descriptor is missing open it to /dev/null */
 957 static void sanitize_stdfds(void)
 958 {
 959         int fd = open("/dev/null", O_RDWR, 0);
 960         while (fd != -1 && fd < 2)
 961                 fd = dup(fd);
 962         if (fd == -1)
 963                 die("open /dev/null or dup failed: %s", strerror(errno));
 964         if (fd > 2)
 965                 close(fd);
 966 }
 967
 968 static void daemonize(void)
 969 {
 970         switch (fork()) {
 971                 case 0:
 972                         break;
 973                 case -1:
 974                         die("fork failed: %s", strerror(errno));
 975                 default:
 976                         exit(0);
 977         }
 978         if (setsid() == -1)
 979                 die("setsid failed: %s", strerror(errno));
 980         close(0);
 981         close(1);
 982         close(2);
 983         sanitize_stdfds();
 984 }
 985
 986 static void store_pid(const char *path)
 987 {
 988         FILE *f = fopen(path, "w");
 989         if (!f)
 990                 die("cannot open pid file %s: %s", path, strerror(errno));
 991         if (fprintf(f, "%d\n", getpid()) < 0 || fclose(f) != 0)
 992                 die("failed to write pid file %s: %s", path, strerror(errno));
 993 }
 994
 995 static int serve(char *listen_addr, int listen_port, struct passwd *pass, gid_t gid)
 996 {
 997         int socknum, *socklist;
 998
 999         socknum = socksetup(listen_addr, listen_port, &socklist);
1000         if (socknum == 0)
1001                 die("unable to allocate any listen sockets on host %s port %u",
1002                     listen_addr, listen_port);
1003
1004         if (pass && gid &&
1005             (initgroups(pass->pw_name, gid) || setgid (gid) ||
1006              setuid(pass->pw_uid)))
1007                 die("cannot drop privileges");
1008
1009         return service_loop(socknum, socklist);
1010 }
1011
1012 int main(int argc, char **argv)
1013 {
1014         int listen_port = 0;
1015         char *listen_addr = NULL;
1016         int inetd_mode = 0;
1017         const char *pid_file = NULL, *user_name = NULL, *group_name = NULL;
1018         int detach = 0;
1019         struct passwd *pass = NULL;
1020         struct group *group;
1021         gid_t gid = 0;
1022         int i;
1023
1024         /* Without this we cannot rely on waitpid() to tell
1025          * what happened to our children.
1026          */
1027         signal(SIGCHLD, SIG_DFL);
1028
1029         for (i = 1; i < argc; i++) {
1030                 char *arg = argv[i];
1031
1032                 if (!prefixcmp(arg, "--listen=")) {
1033                     char *p = arg + 9;
1034                     char *ph = listen_addr = xmalloc(strlen(arg + 9) + 1);
1035                     while (*p)
1036                         *ph++ = tolower(*p++);
1037                     *ph = 0;
1038                     continue;
1039                 }
1040                 if (!prefixcmp(arg, "--port=")) {
1041                         char *end;
1042                         unsigned long n;
1043                         n = strtoul(arg+7, &end, 0);
1044                         if (arg[7] && !*end) {
1045                                 listen_port = n;
1046                                 continue;
1047                         }
1048                 }
1049                 if (!strcmp(arg, "--inetd")) {
1050                         inetd_mode = 1;
1051                         log_syslog = 1;
1052                         continue;
1053                 }
1054                 if (!strcmp(arg, "--verbose")) {
1055                         verbose = 1;
1056                         continue;
1057                 }
1058                 if (!strcmp(arg, "--syslog")) {
1059                         log_syslog = 1;
1060                         continue;
1061                 }
1062                 if (!strcmp(arg, "--export-all")) {
1063                         export_all_trees = 1;
1064                         continue;
1065                 }
1066                 if (!prefixcmp(arg, "--timeout=")) {
1067                         timeout = atoi(arg+10);
1068                         continue;
1069                 }
1070                 if (!prefixcmp(arg, "--init-timeout=")) {
1071                         init_timeout = atoi(arg+15);
1072                         continue;
1073                 }
1074                 if (!strcmp(arg, "--strict-paths")) {
1075                         strict_paths = 1;
1076                         continue;
1077                 }
1078                 if (!prefixcmp(arg, "--base-path=")) {
1079                         base_path = arg+12;
1080                         continue;
1081                 }
1082                 if (!strcmp(arg, "--base-path-relaxed")) {
1083                         base_path_relaxed = 1;
1084                         continue;
1085                 }
1086                 if (!prefixcmp(arg, "--interpolated-path=")) {
1087                         interpolated_path = arg+20;
1088                         continue;
1089                 }
1090                 if (!strcmp(arg, "--reuseaddr")) {
1091                         reuseaddr = 1;
1092                         continue;
1093                 }
1094                 if (!strcmp(arg, "--user-path")) {
1095                         user_path = "";
1096                         continue;
1097                 }
1098                 if (!prefixcmp(arg, "--user-path=")) {
1099                         user_path = arg + 12;
1100                         continue;
1101                 }
1102                 if (!prefixcmp(arg, "--pid-file=")) {
1103                         pid_file = arg + 11;
1104                         continue;
1105                 }
1106                 if (!strcmp(arg, "--detach")) {
1107                         detach = 1;
1108                         log_syslog = 1;
1109                         continue;
1110                 }
1111                 if (!prefixcmp(arg, "--user=")) {
1112                         user_name = arg + 7;
1113                         continue;
1114                 }
1115                 if (!prefixcmp(arg, "--group=")) {
1116                         group_name = arg + 8;
1117                         continue;
1118                 }
1119                 if (!prefixcmp(arg, "--enable=")) {
1120                         enable_service(arg + 9, 1);
1121                         continue;
1122                 }
1123                 if (!prefixcmp(arg, "--disable=")) {
1124                         enable_service(arg + 10, 0);
1125                         continue;
1126                 }
1127                 if (!prefixcmp(arg, "--allow-override=")) {
1128                         make_service_overridable(arg + 17, 1);
1129                         continue;
1130                 }
1131                 if (!prefixcmp(arg, "--forbid-override=")) {
1132                         make_service_overridable(arg + 18, 0);
1133                         continue;
1134                 }
1135                 if (!strcmp(arg, "--")) {
1136                         ok_paths = &argv[i+1];
1137                         break;
1138                 } else if (arg[0] != '-') {
1139                         ok_paths = &argv[i];
1140                         break;
1141                 }
1142
1143                 usage(daemon_usage);
1144         }
1145
1146         if (inetd_mode && (group_name || user_name))
1147                 die("--user and --group are incompatible with --inetd");
1148
1149         if (inetd_mode && (listen_port || listen_addr))
1150                 die("--listen= and --port= are incompatible with --inetd");
1151         else if (listen_port == 0)
1152                 listen_port = DEFAULT_GIT_PORT;
1153
1154         if (group_name && !user_name)
1155                 die("--group supplied without --user");
1156
1157         if (user_name) {
1158                 pass = getpwnam(user_name);
1159                 if (!pass)
1160                         die("user not found - %s", user_name);
1161
1162                 if (!group_name)
1163                         gid = pass->pw_gid;
1164                 else {
1165                         group = getgrnam(group_name);
1166                         if (!group)
1167                                 die("group not found - %s", group_name);
1168
1169                         gid = group->gr_gid;
1170                 }
1171         }
1172
1173         if (log_syslog) {
1174                 openlog("git-daemon", 0, LOG_DAEMON);
1175                 set_die_routine(daemon_die);
1176         }
1177
1178         if (strict_paths && (!ok_paths || !*ok_paths))
1179                 die("option --strict-paths requires a whitelist");
1180
1181         if (inetd_mode) {
1182                 struct sockaddr_storage ss;
1183                 struct sockaddr *peer = (struct sockaddr *)&ss;
1184                 socklen_t slen = sizeof(ss);
1185
1186                 freopen("/dev/null", "w", stderr);
1187
1188                 if (getpeername(0, peer, &slen))
1189                         peer = NULL;
1190
1191                 return execute(peer);
1192         }
1193
1194         if (detach)
1195                 daemonize();
1196         else
1197                 sanitize_stdfds();
1198
1199         if (pid_file)
1200                 store_pid(pid_file);
1201
1202         return serve(listen_addr, listen_port, pass, gid);
1203 }