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