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