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         { "%%", 0},
  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 /*
 409  * Separate the "extra args" information as supplied by the client connection.
 410  * Any resulting data is squirrelled away in the given interpolation table.
 411  */
 412 static void parse_extra_args(struct interp *table, char *extra_args, int buflen)
 413 {
 414         char *val;
 415         int vallen;
 416         char *end = extra_args + buflen;
 417
 418         while (extra_args < end && *extra_args) {
 419                 saw_extended_args = 1;
 420                 if (strncasecmp("host=", extra_args, 5) == 0) {
 421                         val = extra_args + 5;
 422                         vallen = strlen(val) + 1;
 423                         if (*val) {
 424                                 /* Split <host>:<port> at colon. */
 425                                 char *host = val;
 426                                 char *port = strrchr(host, ':');
 427                                 if (port) {
 428                                         *port = 0;
 429                                         port++;
 430                                         interp_set_entry(table, INTERP_SLOT_PORT, port);
 431                                 }
 432                                 interp_set_entry(table, INTERP_SLOT_HOST, host);
 433                         }
 434
 435                         /* On to the next one */
 436                         extra_args = val + vallen;
 437                 }
 438         }
 439 }
 440
 441 void fill_in_extra_table_entries(struct interp *itable)
 442 {
 443         char *hp;
 444
 445         /*
 446          * Replace literal host with lowercase-ized hostname.
 447          */
 448         hp = interp_table[INTERP_SLOT_HOST].value;
 449         for ( ; *hp; hp++)
 450                 *hp = tolower(*hp);
 451
 452         /*
 453          * Locate canonical hostname and its IP address.
 454          */
 455 #ifndef NO_IPV6
 456         {
 457                 struct addrinfo hints;
 458                 struct addrinfo *ai, *ai0;
 459                 int gai;
 460                 static char addrbuf[HOST_NAME_MAX + 1];
 461
 462                 memset(&hints, 0, sizeof(hints));
 463                 hints.ai_flags = AI_CANONNAME;
 464
 465                 gai = getaddrinfo(interp_table[INTERP_SLOT_HOST].value, 0, &hints, &ai0);
 466                 if (!gai) {
 467                         for (ai = ai0; ai; ai = ai->ai_next) {
 468                                 struct sockaddr_in *sin_addr = (void *)ai->ai_addr;
 469
 470                                 inet_ntop(AF_INET, &sin_addr->sin_addr,
 471                                           addrbuf, sizeof(addrbuf));
 472                                 interp_set_entry(interp_table,
 473                                                  INTERP_SLOT_CANON_HOST, ai->ai_canonname);
 474                                 interp_set_entry(interp_table,
 475                                                  INTERP_SLOT_IP, addrbuf);
 476                                 break;
 477                         }
 478                         freeaddrinfo(ai0);
 479                 }
 480         }
 481 #else
 482         {
 483                 struct hostent *hent;
 484                 struct sockaddr_in sa;
 485                 char **ap;
 486                 static char addrbuf[HOST_NAME_MAX + 1];
 487
 488                 hent = gethostbyname(interp_table[INTERP_SLOT_HOST].value);
 489
 490                 ap = hent->h_addr_list;
 491                 memset(&sa, 0, sizeof sa);
 492                 sa.sin_family = hent->h_addrtype;
 493                 sa.sin_port = htons(0);
 494                 memcpy(&sa.sin_addr, *ap, hent->h_length);
 495
 496                 inet_ntop(hent->h_addrtype, &sa.sin_addr,
 497                           addrbuf, sizeof(addrbuf));
 498
 499                 interp_set_entry(interp_table, INTERP_SLOT_CANON_HOST, hent->h_name);
 500                 interp_set_entry(interp_table, INTERP_SLOT_IP, addrbuf);
 501         }
 502 #endif
 503 }
 504
 505
 506 static int execute(struct sockaddr *addr)
 507 {
 508         static char line[1000];
 509         int pktlen, len, i;
 510
 511         if (addr) {
 512                 char addrbuf[256] = "";
 513                 int port = -1;
 514
 515                 if (addr->sa_family == AF_INET) {
 516                         struct sockaddr_in *sin_addr = (void *) addr;
 517                         inet_ntop(addr->sa_family, &sin_addr->sin_addr, addrbuf, sizeof(addrbuf));
 518                         port = sin_addr->sin_port;
 519 #ifndef NO_IPV6
 520                 } else if (addr && addr->sa_family == AF_INET6) {
 521                         struct sockaddr_in6 *sin6_addr = (void *) addr;
 522
 523                         char *buf = addrbuf;
 524                         *buf++ = '['; *buf = '\0'; /* stpcpy() is cool */
 525                         inet_ntop(AF_INET6, &sin6_addr->sin6_addr, buf, sizeof(addrbuf) - 1);
 526                         strcat(buf, "]");
 527
 528                         port = sin6_addr->sin6_port;
 529 #endif
 530                 }
 531                 loginfo("Connection from %s:%d", addrbuf, port);
 532         }
 533
 534         alarm(init_timeout ? init_timeout : timeout);
 535         pktlen = packet_read_line(0, line, sizeof(line));
 536         alarm(0);
 537
 538         len = strlen(line);
 539         if (pktlen != len)
 540                 loginfo("Extended attributes (%d bytes) exist <%.*s>",
 541                         (int) pktlen - len,
 542                         (int) pktlen - len, line + len + 1);
 543         if (len && line[len-1] == '\n')
 544                 line[--len] = 0;
 545
 546         /*
 547          * Initialize the path interpolation table for this connection.
 548          */
 549         interp_clear_table(interp_table, ARRAY_SIZE(interp_table));
 550         interp_set_entry(interp_table, INTERP_SLOT_PERCENT, "%");
 551
 552         if (len != pktlen) {
 553             parse_extra_args(interp_table, line + len + 1, pktlen - len - 1);
 554             fill_in_extra_table_entries(interp_table);
 555         }
 556
 557         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 558                 struct daemon_service *s = &(daemon_service[i]);
 559                 int namelen = strlen(s->name);
 560                 if (!strncmp("git-", line, 4) &&
 561                     !strncmp(s->name, line + 4, namelen) &&
 562                     line[namelen + 4] == ' ') {
 563                         /*
 564                          * Note: The directory here is probably context sensitive,
 565                          * and might depend on the actual service being performed.
 566                          */
 567                         interp_set_entry(interp_table,
 568                                          INTERP_SLOT_DIR, line + namelen + 5);
 569                         return run_service(interp_table, s);
 570                 }
 571         }
 572
 573         logerror("Protocol error: '%s'", line);
 574         return -1;
 575 }
 576
 577
 578 /*
 579  * We count spawned/reaped separately, just to avoid any
 580  * races when updating them from signals. The SIGCHLD handler
 581  * will only update children_reaped, and the fork logic will
 582  * only update children_spawned.
 583  *
 584  * MAX_CHILDREN should be a power-of-two to make the modulus
 585  * operation cheap. It should also be at least twice
 586  * the maximum number of connections we will ever allow.
 587  */
 588 #define MAX_CHILDREN 128
 589
 590 static int max_connections = 25;
 591
 592 /* These are updated by the signal handler */
 593 static volatile unsigned int children_reaped;
 594 static pid_t dead_child[MAX_CHILDREN];
 595
 596 /* These are updated by the main loop */
 597 static unsigned int children_spawned;
 598 static unsigned int children_deleted;
 599
 600 static struct child {
 601         pid_t pid;
 602         int addrlen;
 603         struct sockaddr_storage address;
 604 } live_child[MAX_CHILDREN];
 605
 606 static void add_child(int idx, pid_t pid, struct sockaddr *addr, int addrlen)
 607 {
 608         live_child[idx].pid = pid;
 609         live_child[idx].addrlen = addrlen;
 610         memcpy(&live_child[idx].address, addr, addrlen);
 611 }
 612
 613 /*
 614  * Walk from "deleted" to "spawned", and remove child "pid".
 615  *
 616  * We move everything up by one, since the new "deleted" will
 617  * be one higher.
 618  */
 619 static void remove_child(pid_t pid, unsigned deleted, unsigned spawned)
 620 {
 621         struct child n;
 622
 623         deleted %= MAX_CHILDREN;
 624         spawned %= MAX_CHILDREN;
 625         if (live_child[deleted].pid == pid) {
 626                 live_child[deleted].pid = -1;
 627                 return;
 628         }
 629         n = live_child[deleted];
 630         for (;;) {
 631                 struct child m;
 632                 deleted = (deleted + 1) % MAX_CHILDREN;
 633                 if (deleted == spawned)
 634                         die("could not find dead child %d\n", pid);
 635                 m = live_child[deleted];
 636                 live_child[deleted] = n;
 637                 if (m.pid == pid)
 638                         return;
 639                 n = m;
 640         }
 641 }
 642
 643 /*
 644  * This gets called if the number of connections grows
 645  * past "max_connections".
 646  *
 647  * We _should_ start off by searching for connections
 648  * from the same IP, and if there is some address wth
 649  * multiple connections, we should kill that first.
 650  *
 651  * As it is, we just "randomly" kill 25% of the connections,
 652  * and our pseudo-random generator sucks too. I have no
 653  * shame.
 654  *
 655  * Really, this is just a place-holder for a _real_ algorithm.
 656  */
 657 static void kill_some_children(int signo, unsigned start, unsigned stop)
 658 {
 659         start %= MAX_CHILDREN;
 660         stop %= MAX_CHILDREN;
 661         while (start != stop) {
 662                 if (!(start & 3))
 663                         kill(live_child[start].pid, signo);
 664                 start = (start + 1) % MAX_CHILDREN;
 665         }
 666 }
 667
 668 static void check_max_connections(void)
 669 {
 670         for (;;) {
 671                 int active;
 672                 unsigned spawned, reaped, deleted;
 673
 674                 spawned = children_spawned;
 675                 reaped = children_reaped;
 676                 deleted = children_deleted;
 677
 678                 while (deleted < reaped) {
 679                         pid_t pid = dead_child[deleted % MAX_CHILDREN];
 680                         remove_child(pid, deleted, spawned);
 681                         deleted++;
 682                 }
 683                 children_deleted = deleted;
 684
 685                 active = spawned - deleted;
 686                 if (active <= max_connections)
 687                         break;
 688
 689                 /* Kill some unstarted connections with SIGTERM */
 690                 kill_some_children(SIGTERM, deleted, spawned);
 691                 if (active <= max_connections << 1)
 692                         break;
 693
 694                 /* If the SIGTERM thing isn't helping use SIGKILL */
 695                 kill_some_children(SIGKILL, deleted, spawned);
 696                 sleep(1);
 697         }
 698 }
 699
 700 static void handle(int incoming, struct sockaddr *addr, int addrlen)
 701 {
 702         pid_t pid = fork();
 703
 704         if (pid) {
 705                 unsigned idx;
 706
 707                 close(incoming);
 708                 if (pid < 0)
 709                         return;
 710
 711                 idx = children_spawned % MAX_CHILDREN;
 712                 children_spawned++;
 713                 add_child(idx, pid, addr, addrlen);
 714
 715                 check_max_connections();
 716                 return;
 717         }
 718
 719         dup2(incoming, 0);
 720         dup2(incoming, 1);
 721         close(incoming);
 722
 723         exit(execute(addr));
 724 }
 725
 726 static void child_handler(int signo)
 727 {
 728         for (;;) {
 729                 int status;
 730                 pid_t pid = waitpid(-1, &status, WNOHANG);
 731
 732                 if (pid > 0) {
 733                         unsigned reaped = children_reaped;
 734                         dead_child[reaped % MAX_CHILDREN] = pid;
 735                         children_reaped = reaped + 1;
 736                         /* XXX: Custom logging, since we don't wanna getpid() */
 737                         if (verbose) {
 738                                 const char *dead = "";
 739                                 if (!WIFEXITED(status) || WEXITSTATUS(status) > 0)
 740                                         dead = " (with error)";
 741                                 if (log_syslog)
 742                                         syslog(LOG_INFO, "[%d] Disconnected%s", pid, dead);
 743                                 else
 744                                         fprintf(stderr, "[%d] Disconnected%s\n", pid, dead);
 745                         }
 746                         continue;
 747                 }
 748                 break;
 749         }
 750 }
 751
 752 static int set_reuse_addr(int sockfd)
 753 {
 754         int on = 1;
 755
 756         if (!reuseaddr)
 757                 return 0;
 758         return setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
 759                           &on, sizeof(on));
 760 }
 761
 762 #ifndef NO_IPV6
 763
 764 static int socksetup(char *listen_addr, int listen_port, int **socklist_p)
 765 {
 766         int socknum = 0, *socklist = NULL;
 767         int maxfd = -1;
 768         char pbuf[NI_MAXSERV];
 769         struct addrinfo hints, *ai0, *ai;
 770         int gai;
 771
 772         sprintf(pbuf, "%d", listen_port);
 773         memset(&hints, 0, sizeof(hints));
 774         hints.ai_family = AF_UNSPEC;
 775         hints.ai_socktype = SOCK_STREAM;
 776         hints.ai_protocol = IPPROTO_TCP;
 777         hints.ai_flags = AI_PASSIVE;
 778
 779         gai = getaddrinfo(listen_addr, pbuf, &hints, &ai0);
 780         if (gai)
 781                 die("getaddrinfo() failed: %s\n", gai_strerror(gai));
 782
 783         for (ai = ai0; ai; ai = ai->ai_next) {
 784                 int sockfd;
 785
 786                 sockfd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
 787                 if (sockfd < 0)
 788                         continue;
 789                 if (sockfd >= FD_SETSIZE) {
 790                         error("too large socket descriptor.");
 791                         close(sockfd);
 792                         continue;
 793                 }
 794
 795 #ifdef IPV6_V6ONLY
 796                 if (ai->ai_family == AF_INET6) {
 797                         int on = 1;
 798                         setsockopt(sockfd, IPPROTO_IPV6, IPV6_V6ONLY,
 799                                    &on, sizeof(on));
 800                         /* Note: error is not fatal */
 801                 }
 802 #endif
 803
 804                 if (set_reuse_addr(sockfd)) {
 805                         close(sockfd);
 806                         continue;
 807                 }
 808
 809                 if (bind(sockfd, ai->ai_addr, ai->ai_addrlen) < 0) {
 810                         close(sockfd);
 811                         continue;       /* not fatal */
 812                 }
 813                 if (listen(sockfd, 5) < 0) {
 814                         close(sockfd);
 815                         continue;       /* not fatal */
 816                 }
 817
 818                 socklist = xrealloc(socklist, sizeof(int) * (socknum + 1));
 819                 socklist[socknum++] = sockfd;
 820
 821                 if (maxfd < sockfd)
 822                         maxfd = sockfd;
 823         }
 824
 825         freeaddrinfo(ai0);
 826
 827         *socklist_p = socklist;
 828         return socknum;
 829 }
 830
 831 #else /* NO_IPV6 */
 832
 833 static int socksetup(char *lisen_addr, int listen_port, int **socklist_p)
 834 {
 835         struct sockaddr_in sin;
 836         int sockfd;
 837
 838         memset(&sin, 0, sizeof sin);
 839         sin.sin_family = AF_INET;
 840         sin.sin_port = htons(listen_port);
 841
 842         if (listen_addr) {
 843                 /* Well, host better be an IP address here. */
 844                 if (inet_pton(AF_INET, listen_addr, &sin.sin_addr.s_addr) <= 0)
 845                         return 0;
 846         } else {
 847                 sin.sin_addr.s_addr = htonl(INADDR_ANY);
 848         }
 849
 850         sockfd = socket(AF_INET, SOCK_STREAM, 0);
 851         if (sockfd < 0)
 852                 return 0;
 853
 854         if (set_reuse_addr(sockfd)) {
 855                 close(sockfd);
 856                 return 0;
 857         }
 858
 859         if ( bind(sockfd, (struct sockaddr *)&sin, sizeof sin) < 0 ) {
 860                 close(sockfd);
 861                 return 0;
 862         }
 863
 864         if (listen(sockfd, 5) < 0) {
 865                 close(sockfd);
 866                 return 0;
 867         }
 868
 869         *socklist_p = xmalloc(sizeof(int));
 870         **socklist_p = sockfd;
 871         return 1;
 872 }
 873
 874 #endif
 875
 876 static int service_loop(int socknum, int *socklist)
 877 {
 878         struct pollfd *pfd;
 879         int i;
 880
 881         pfd = xcalloc(socknum, sizeof(struct pollfd));
 882
 883         for (i = 0; i < socknum; i++) {
 884                 pfd[i].fd = socklist[i];
 885                 pfd[i].events = POLLIN;
 886         }
 887
 888         signal(SIGCHLD, child_handler);
 889
 890         for (;;) {
 891                 int i;
 892
 893                 if (poll(pfd, socknum, -1) < 0) {
 894                         if (errno != EINTR) {
 895                                 error("poll failed, resuming: %s",
 896                                       strerror(errno));
 897                                 sleep(1);
 898                         }
 899                         continue;
 900                 }
 901
 902                 for (i = 0; i < socknum; i++) {
 903                         if (pfd[i].revents & POLLIN) {
 904                                 struct sockaddr_storage ss;
 905                                 unsigned int sslen = sizeof(ss);
 906                                 int incoming = accept(pfd[i].fd, (struct sockaddr *)&ss, &sslen);
 907                                 if (incoming < 0) {
 908                                         switch (errno) {
 909                                         case EAGAIN:
 910                                         case EINTR:
 911                                         case ECONNABORTED:
 912                                                 continue;
 913                                         default:
 914                                                 die("accept returned %s", strerror(errno));
 915                                         }
 916                                 }
 917                                 handle(incoming, (struct sockaddr *)&ss, sslen);
 918                         }
 919                 }
 920         }
 921 }
 922
 923 /* if any standard file descriptor is missing open it to /dev/null */
 924 static void sanitize_stdfds(void)
 925 {
 926         int fd = open("/dev/null", O_RDWR, 0);
 927         while (fd != -1 && fd < 2)
 928                 fd = dup(fd);
 929         if (fd == -1)
 930                 die("open /dev/null or dup failed: %s", strerror(errno));
 931         if (fd > 2)
 932                 close(fd);
 933 }
 934
 935 static void daemonize(void)
 936 {
 937         switch (fork()) {
 938                 case 0:
 939                         break;
 940                 case -1:
 941                         die("fork failed: %s", strerror(errno));
 942                 default:
 943                         exit(0);
 944         }
 945         if (setsid() == -1)
 946                 die("setsid failed: %s", strerror(errno));
 947         close(0);
 948         close(1);
 949         close(2);
 950         sanitize_stdfds();
 951 }
 952
 953 static void store_pid(const char *path)
 954 {
 955         FILE *f = fopen(path, "w");
 956         if (!f)
 957                 die("cannot open pid file %s: %s", path, strerror(errno));
 958         fprintf(f, "%d\n", getpid());
 959         fclose(f);
 960 }
 961
 962 static int serve(char *listen_addr, int listen_port, struct passwd *pass, gid_t gid)
 963 {
 964         int socknum, *socklist;
 965
 966         socknum = socksetup(listen_addr, listen_port, &socklist);
 967         if (socknum == 0)
 968                 die("unable to allocate any listen sockets on host %s port %u",
 969                     listen_addr, listen_port);
 970
 971         if (pass && gid &&
 972             (initgroups(pass->pw_name, gid) || setgid (gid) ||
 973              setuid(pass->pw_uid)))
 974                 die("cannot drop privileges");
 975
 976         return service_loop(socknum, socklist);
 977 }
 978
 979 int main(int argc, char **argv)
 980 {
 981         int listen_port = 0;
 982         char *listen_addr = NULL;
 983         int inetd_mode = 0;
 984         const char *pid_file = NULL, *user_name = NULL, *group_name = NULL;
 985         int detach = 0;
 986         struct passwd *pass = NULL;
 987         struct group *group;
 988         gid_t gid = 0;
 989         int i;
 990
 991         /* Without this we cannot rely on waitpid() to tell
 992          * what happened to our children.
 993          */
 994         signal(SIGCHLD, SIG_DFL);
 995
 996         for (i = 1; i < argc; i++) {
 997                 char *arg = argv[i];
 998
 999                 if (!strncmp(arg, "--listen=", 9)) {
1000                     char *p = arg + 9;
1001                     char *ph = listen_addr = xmalloc(strlen(arg + 9) + 1);
1002                     while (*p)
1003                         *ph++ = tolower(*p++);
1004                     *ph = 0;
1005                     continue;
1006                 }
1007                 if (!strncmp(arg, "--port=", 7)) {
1008                         char *end;
1009                         unsigned long n;
1010                         n = strtoul(arg+7, &end, 0);
1011                         if (arg[7] && !*end) {
1012                                 listen_port = n;
1013                                 continue;
1014                         }
1015                 }
1016                 if (!strcmp(arg, "--inetd")) {
1017                         inetd_mode = 1;
1018                         log_syslog = 1;
1019                         continue;
1020                 }
1021                 if (!strcmp(arg, "--verbose")) {
1022                         verbose = 1;
1023                         continue;
1024                 }
1025                 if (!strcmp(arg, "--syslog")) {
1026                         log_syslog = 1;
1027                         continue;
1028                 }
1029                 if (!strcmp(arg, "--export-all")) {
1030                         export_all_trees = 1;
1031                         continue;
1032                 }
1033                 if (!strncmp(arg, "--timeout=", 10)) {
1034                         timeout = atoi(arg+10);
1035                         continue;
1036                 }
1037                 if (!strncmp(arg, "--init-timeout=", 15)) {
1038                         init_timeout = atoi(arg+15);
1039                         continue;
1040                 }
1041                 if (!strcmp(arg, "--strict-paths")) {
1042                         strict_paths = 1;
1043                         continue;
1044                 }
1045                 if (!strncmp(arg, "--base-path=", 12)) {
1046                         base_path = arg+12;
1047                         continue;
1048                 }
1049                 if (!strncmp(arg, "--interpolated-path=", 20)) {
1050                         interpolated_path = arg+20;
1051                         continue;
1052                 }
1053                 if (!strcmp(arg, "--reuseaddr")) {
1054                         reuseaddr = 1;
1055                         continue;
1056                 }
1057                 if (!strcmp(arg, "--user-path")) {
1058                         user_path = "";
1059                         continue;
1060                 }
1061                 if (!strncmp(arg, "--user-path=", 12)) {
1062                         user_path = arg + 12;
1063                         continue;
1064                 }
1065                 if (!strncmp(arg, "--pid-file=", 11)) {
1066                         pid_file = arg + 11;
1067                         continue;
1068                 }
1069                 if (!strcmp(arg, "--detach")) {
1070                         detach = 1;
1071                         log_syslog = 1;
1072                         continue;
1073                 }
1074                 if (!strncmp(arg, "--user=", 7)) {
1075                         user_name = arg + 7;
1076                         continue;
1077                 }
1078                 if (!strncmp(arg, "--group=", 8)) {
1079                         group_name = arg + 8;
1080                         continue;
1081                 }
1082                 if (!strncmp(arg, "--enable=", 9)) {
1083                         enable_service(arg + 9, 1);
1084                         continue;
1085                 }
1086                 if (!strncmp(arg, "--disable=", 10)) {
1087                         enable_service(arg + 10, 0);
1088                         continue;
1089                 }
1090                 if (!strncmp(arg, "--allow-override=", 17)) {
1091                         make_service_overridable(arg + 17, 1);
1092                         continue;
1093                 }
1094                 if (!strncmp(arg, "--forbid-override=", 18)) {
1095                         make_service_overridable(arg + 18, 0);
1096                         continue;
1097                 }
1098                 if (!strcmp(arg, "--")) {
1099                         ok_paths = &argv[i+1];
1100                         break;
1101                 } else if (arg[0] != '-') {
1102                         ok_paths = &argv[i];
1103                         break;
1104                 }
1105
1106                 usage(daemon_usage);
1107         }
1108
1109         if (inetd_mode && (group_name || user_name))
1110                 die("--user and --group are incompatible with --inetd");
1111
1112         if (inetd_mode && (listen_port || listen_addr))
1113                 die("--listen= and --port= are incompatible with --inetd");
1114         else if (listen_port == 0)
1115                 listen_port = DEFAULT_GIT_PORT;
1116
1117         if (group_name && !user_name)
1118                 die("--group supplied without --user");
1119
1120         if (user_name) {
1121                 pass = getpwnam(user_name);
1122                 if (!pass)
1123                         die("user not found - %s", user_name);
1124
1125                 if (!group_name)
1126                         gid = pass->pw_gid;
1127                 else {
1128                         group = getgrnam(group_name);
1129                         if (!group)
1130                                 die("group not found - %s", group_name);
1131
1132                         gid = group->gr_gid;
1133                 }
1134         }
1135
1136         if (log_syslog) {
1137                 openlog("git-daemon", 0, LOG_DAEMON);
1138                 set_die_routine(daemon_die);
1139         }
1140
1141         if (strict_paths && (!ok_paths || !*ok_paths))
1142                 die("option --strict-paths requires a whitelist");
1143
1144         if (inetd_mode) {
1145                 struct sockaddr_storage ss;
1146                 struct sockaddr *peer = (struct sockaddr *)&ss;
1147                 socklen_t slen = sizeof(ss);
1148
1149                 freopen("/dev/null", "w", stderr);
1150
1151                 if (getpeername(0, peer, &slen))
1152                         peer = NULL;
1153
1154                 return execute(peer);
1155         }
1156
1157         if (detach)
1158                 daemonize();
1159         else
1160                 sanitize_stdfds();
1161
1162         if (pid_file)
1163                 store_pid(pid_file);
1164
1165         return serve(listen_addr, listen_port, pass, gid);
1166 }