daemon.c

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