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 #ifndef NI_MAXSERV
  13 #define NI_MAXSERV 32
  14 #endif
  15
  16 static int log_syslog;
  17 static int verbose;
  18 static int reuseaddr;
  19
  20 static const char daemon_usage[] =
  21 "git-daemon [--verbose] [--syslog] [--export-all]\n"
  22 "           [--timeout=n] [--init-timeout=n] [--strict-paths]\n"
  23 "           [--base-path=path] [--base-path-relaxed]\n"
  24 "           [--user-path | --user-path=path]\n"
  25 "           [--interpolated-path=path]\n"
  26 "           [--reuseaddr] [--detach] [--pid-file=file]\n"
  27 "           [--[enable|disable|allow-override|forbid-override]=service]\n"
  28 "           [--inetd | [--listen=host_or_ipaddr] [--port=n]\n"
  29 "                      [--user=user [--group=group]]\n"
  30 "           [directory...]";
  31
  32 /* List of acceptable pathname prefixes */
  33 static char **ok_paths;
  34 static int strict_paths;
  35
  36 /* If this is set, git-daemon-export-ok is not required */
  37 static int export_all_trees;
  38
  39 /* Take all paths relative to this one if non-NULL */
  40 static char *base_path;
  41 static char *interpolated_path;
  42 static int base_path_relaxed;
  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_in_full(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         int retried_path = 0;
 190         char *path;
 191         char *dir;
 192
 193         dir = itable[INTERP_SLOT_DIR].value;
 194
 195         if (avoid_alias(dir)) {
 196                 logerror("'%s': aliased", dir);
 197                 return NULL;
 198         }
 199
 200         if (*dir == '~') {
 201                 if (!user_path) {
 202                         logerror("'%s': User-path not allowed", dir);
 203                         return NULL;
 204                 }
 205                 if (*user_path) {
 206                         /* Got either "~alice" or "~alice/foo";
 207                          * rewrite them to "~alice/%s" or
 208                          * "~alice/%s/foo".
 209                          */
 210                         int namlen, restlen = strlen(dir);
 211                         char *slash = strchr(dir, '/');
 212                         if (!slash)
 213                                 slash = dir + restlen;
 214                         namlen = slash - dir;
 215                         restlen -= namlen;
 216                         loginfo("userpath <%s>, request <%s>, namlen %d, restlen %d, slash <%s>", user_path, dir, namlen, restlen, slash);
 217                         snprintf(rpath, PATH_MAX, "%.*s/%s%.*s",
 218                                  namlen, dir, user_path, restlen, slash);
 219                         dir = rpath;
 220                 }
 221         }
 222         else if (interpolated_path && saw_extended_args) {
 223                 if (*dir != '/') {
 224                         /* Allow only absolute */
 225                         logerror("'%s': Non-absolute path denied (interpolated-path active)", dir);
 226                         return NULL;
 227                 }
 228
 229                 interpolate(interp_path, PATH_MAX, interpolated_path,
 230                             interp_table, ARRAY_SIZE(interp_table));
 231                 loginfo("Interpolated dir '%s'", interp_path);
 232
 233                 dir = interp_path;
 234         }
 235         else if (base_path) {
 236                 if (*dir != '/') {
 237                         /* Allow only absolute */
 238                         logerror("'%s': Non-absolute path denied (base-path active)", dir);
 239                         return NULL;
 240                 }
 241                 snprintf(rpath, PATH_MAX, "%s%s", base_path, dir);
 242                 dir = rpath;
 243         }
 244
 245         do {
 246                 path = enter_repo(dir, strict_paths);
 247                 if (path)
 248                         break;
 249
 250                 /*
 251                  * if we fail and base_path_relaxed is enabled, try without
 252                  * prefixing the base path
 253                  */
 254                 if (base_path && base_path_relaxed && !retried_path) {
 255                         dir = itable[INTERP_SLOT_DIR].value;
 256                         retried_path = 1;
 257                         continue;
 258                 }
 259                 break;
 260         } while (1);
 261
 262         if (!path) {
 263                 logerror("'%s': unable to chdir or not a git archive", dir);
 264                 return NULL;
 265         }
 266
 267         if ( ok_paths && *ok_paths ) {
 268                 char **pp;
 269                 int pathlen = strlen(path);
 270
 271                 /* The validation is done on the paths after enter_repo
 272                  * appends optional {.git,.git/.git} and friends, but
 273                  * it does not use getcwd().  So if your /pub is
 274                  * a symlink to /mnt/pub, you can whitelist /pub and
 275                  * do not have to say /mnt/pub.
 276                  * Do not say /pub/.
 277                  */
 278                 for ( pp = ok_paths ; *pp ; pp++ ) {
 279                         int len = strlen(*pp);
 280                         if (len <= pathlen &&
 281                             !memcmp(*pp, path, len) &&
 282                             (path[len] == '\0' ||
 283                              (!strict_paths && path[len] == '/')))
 284                                 return path;
 285                 }
 286         }
 287         else {
 288                 /* be backwards compatible */
 289                 if (!strict_paths)
 290                         return path;
 291         }
 292
 293         logerror("'%s': not in whitelist", path);
 294         return NULL;            /* Fallthrough. Deny by default */
 295 }
 296
 297 typedef int (*daemon_service_fn)(void);
 298 struct daemon_service {
 299         const char *name;
 300         const char *config_name;
 301         daemon_service_fn fn;
 302         int enabled;
 303         int overridable;
 304 };
 305
 306 static struct daemon_service *service_looking_at;
 307 static int service_enabled;
 308
 309 static int git_daemon_config(const char *var, const char *value)
 310 {
 311         if (!prefixcmp(var, "daemon.") &&
 312             !strcmp(var + 7, service_looking_at->config_name)) {
 313                 service_enabled = git_config_bool(var, value);
 314                 return 0;
 315         }
 316
 317         /* we are not interested in parsing any other configuration here */
 318         return 0;
 319 }
 320
 321 static int run_service(struct interp *itable, struct daemon_service *service)
 322 {
 323         const char *path;
 324         int enabled = service->enabled;
 325
 326         loginfo("Request %s for '%s'",
 327                 service->name,
 328                 itable[INTERP_SLOT_DIR].value);
 329
 330         if (!enabled && !service->overridable) {
 331                 logerror("'%s': service not enabled.", service->name);
 332                 errno = EACCES;
 333                 return -1;
 334         }
 335
 336         if (!(path = path_ok(itable)))
 337                 return -1;
 338
 339         /*
 340          * Security on the cheap.
 341          *
 342          * We want a readable HEAD, usable "objects" directory, and
 343          * a "git-daemon-export-ok" flag that says that the other side
 344          * is ok with us doing this.
 345          *
 346          * path_ok() uses enter_repo() and does whitelist checking.
 347          * We only need to make sure the repository is exported.
 348          */
 349
 350         if (!export_all_trees && access("git-daemon-export-ok", F_OK)) {
 351                 logerror("'%s': repository not exported.", path);
 352                 errno = EACCES;
 353                 return -1;
 354         }
 355
 356         if (service->overridable) {
 357                 service_looking_at = service;
 358                 service_enabled = -1;
 359                 git_config(git_daemon_config);
 360                 if (0 <= service_enabled)
 361                         enabled = service_enabled;
 362         }
 363         if (!enabled) {
 364                 logerror("'%s': service not enabled for '%s'",
 365                          service->name, path);
 366                 errno = EACCES;
 367                 return -1;
 368         }
 369
 370         /*
 371          * We'll ignore SIGTERM from now on, we have a
 372          * good client.
 373          */
 374         signal(SIGTERM, SIG_IGN);
 375
 376         return service->fn();
 377 }
 378
 379 static int upload_pack(void)
 380 {
 381         /* Timeout as string */
 382         char timeout_buf[64];
 383
 384         snprintf(timeout_buf, sizeof timeout_buf, "--timeout=%u", timeout);
 385
 386         /* git-upload-pack only ever reads stuff, so this is safe */
 387         execl_git_cmd("upload-pack", "--strict", timeout_buf, ".", NULL);
 388         return -1;
 389 }
 390
 391 static int upload_archive(void)
 392 {
 393         execl_git_cmd("upload-archive", ".", NULL);
 394         return -1;
 395 }
 396
 397 static int receive_pack(void)
 398 {
 399         execl_git_cmd("receive-pack", ".", NULL);
 400         return -1;
 401 }
 402
 403 static struct daemon_service daemon_service[] = {
 404         { "upload-archive", "uploadarch", upload_archive, 0, 1 },
 405         { "upload-pack", "uploadpack", upload_pack, 1, 1 },
 406         { "receive-pack", "receivepack", receive_pack, 0, 1 },
 407 };
 408
 409 static void enable_service(const char *name, int ena) {
 410         int i;
 411         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 412                 if (!strcmp(daemon_service[i].name, name)) {
 413                         daemon_service[i].enabled = ena;
 414                         return;
 415                 }
 416         }
 417         die("No such service %s", name);
 418 }
 419
 420 static void make_service_overridable(const char *name, int ena) {
 421         int i;
 422         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 423                 if (!strcmp(daemon_service[i].name, name)) {
 424                         daemon_service[i].overridable = ena;
 425                         return;
 426                 }
 427         }
 428         die("No such service %s", name);
 429 }
 430
 431 /*
 432  * Separate the "extra args" information as supplied by the client connection.
 433  * Any resulting data is squirreled away in the given interpolation table.
 434  */
 435 static void parse_extra_args(struct interp *table, char *extra_args, int buflen)
 436 {
 437         char *val;
 438         int vallen;
 439         char *end = extra_args + buflen;
 440
 441         while (extra_args < end && *extra_args) {
 442                 saw_extended_args = 1;
 443                 if (strncasecmp("host=", extra_args, 5) == 0) {
 444                         val = extra_args + 5;
 445                         vallen = strlen(val) + 1;
 446                         if (*val) {
 447                                 /* Split <host>:<port> at colon. */
 448                                 char *host = val;
 449                                 char *port = strrchr(host, ':');
 450                                 if (port) {
 451                                         *port = 0;
 452                                         port++;
 453                                         interp_set_entry(table, INTERP_SLOT_PORT, port);
 454                                 }
 455                                 interp_set_entry(table, INTERP_SLOT_HOST, host);
 456                         }
 457
 458                         /* On to the next one */
 459                         extra_args = val + vallen;
 460                 }
 461         }
 462 }
 463
 464 static void fill_in_extra_table_entries(struct interp *itable)
 465 {
 466         char *hp;
 467
 468         /*
 469          * Replace literal host with lowercase-ized hostname.
 470          */
 471         hp = interp_table[INTERP_SLOT_HOST].value;
 472         if (!hp)
 473                 return;
 474         for ( ; *hp; hp++)
 475                 *hp = tolower(*hp);
 476
 477         /*
 478          * Locate canonical hostname and its IP address.
 479          */
 480 #ifndef NO_IPV6
 481         {
 482                 struct addrinfo hints;
 483                 struct addrinfo *ai, *ai0;
 484                 int gai;
 485                 static char addrbuf[HOST_NAME_MAX + 1];
 486
 487                 memset(&hints, 0, sizeof(hints));
 488                 hints.ai_flags = AI_CANONNAME;
 489
 490                 gai = getaddrinfo(interp_table[INTERP_SLOT_HOST].value, 0, &hints, &ai0);
 491                 if (!gai) {
 492                         for (ai = ai0; ai; ai = ai->ai_next) {
 493                                 struct sockaddr_in *sin_addr = (void *)ai->ai_addr;
 494
 495                                 inet_ntop(AF_INET, &sin_addr->sin_addr,
 496                                           addrbuf, sizeof(addrbuf));
 497                                 interp_set_entry(interp_table,
 498                                                  INTERP_SLOT_CANON_HOST, ai->ai_canonname);
 499                                 interp_set_entry(interp_table,
 500                                                  INTERP_SLOT_IP, addrbuf);
 501                                 break;
 502                         }
 503                         freeaddrinfo(ai0);
 504                 }
 505         }
 506 #else
 507         {
 508                 struct hostent *hent;
 509                 struct sockaddr_in sa;
 510                 char **ap;
 511                 static char addrbuf[HOST_NAME_MAX + 1];
 512
 513                 hent = gethostbyname(interp_table[INTERP_SLOT_HOST].value);
 514
 515                 ap = hent->h_addr_list;
 516                 memset(&sa, 0, sizeof sa);
 517                 sa.sin_family = hent->h_addrtype;
 518                 sa.sin_port = htons(0);
 519                 memcpy(&sa.sin_addr, *ap, hent->h_length);
 520
 521                 inet_ntop(hent->h_addrtype, &sa.sin_addr,
 522                           addrbuf, sizeof(addrbuf));
 523
 524                 interp_set_entry(interp_table, INTERP_SLOT_CANON_HOST, hent->h_name);
 525                 interp_set_entry(interp_table, INTERP_SLOT_IP, addrbuf);
 526         }
 527 #endif
 528 }
 529
 530
 531 static int execute(struct sockaddr *addr)
 532 {
 533         static char line[1000];
 534         int pktlen, len, i;
 535
 536         if (addr) {
 537                 char addrbuf[256] = "";
 538                 int port = -1;
 539
 540                 if (addr->sa_family == AF_INET) {
 541                         struct sockaddr_in *sin_addr = (void *) addr;
 542                         inet_ntop(addr->sa_family, &sin_addr->sin_addr, addrbuf, sizeof(addrbuf));
 543                         port = sin_addr->sin_port;
 544 #ifndef NO_IPV6
 545                 } else if (addr && addr->sa_family == AF_INET6) {
 546                         struct sockaddr_in6 *sin6_addr = (void *) addr;
 547
 548                         char *buf = addrbuf;
 549                         *buf++ = '['; *buf = '\0'; /* stpcpy() is cool */
 550                         inet_ntop(AF_INET6, &sin6_addr->sin6_addr, buf, sizeof(addrbuf) - 1);
 551                         strcat(buf, "]");
 552
 553                         port = sin6_addr->sin6_port;
 554 #endif
 555                 }
 556                 loginfo("Connection from %s:%d", addrbuf, port);
 557         }
 558
 559         alarm(init_timeout ? init_timeout : timeout);
 560         pktlen = packet_read_line(0, line, sizeof(line));
 561         alarm(0);
 562
 563         len = strlen(line);
 564         if (pktlen != len)
 565                 loginfo("Extended attributes (%d bytes) exist <%.*s>",
 566                         (int) pktlen - len,
 567                         (int) pktlen - len, line + len + 1);
 568         if (len && line[len-1] == '\n') {
 569                 line[--len] = 0;
 570                 pktlen--;
 571         }
 572
 573         /*
 574          * Initialize the path interpolation table for this connection.
 575          */
 576         interp_clear_table(interp_table, ARRAY_SIZE(interp_table));
 577         interp_set_entry(interp_table, INTERP_SLOT_PERCENT, "%");
 578
 579         if (len != pktlen) {
 580             parse_extra_args(interp_table, line + len + 1, pktlen - len - 1);
 581             fill_in_extra_table_entries(interp_table);
 582         }
 583
 584         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 585                 struct daemon_service *s = &(daemon_service[i]);
 586                 int namelen = strlen(s->name);
 587                 if (!prefixcmp(line, "git-") &&
 588                     !strncmp(s->name, line + 4, namelen) &&
 589                     line[namelen + 4] == ' ') {
 590                         /*
 591                          * Note: The directory here is probably context sensitive,
 592                          * and might depend on the actual service being performed.
 593                          */
 594                         interp_set_entry(interp_table,
 595                                          INTERP_SLOT_DIR, line + namelen + 5);
 596                         return run_service(interp_table, s);
 597                 }
 598         }
 599
 600         logerror("Protocol error: '%s'", line);
 601         return -1;
 602 }
 603
 604
 605 /*
 606  * We count spawned/reaped separately, just to avoid any
 607  * races when updating them from signals. The SIGCHLD handler
 608  * will only update children_reaped, and the fork logic will
 609  * only update children_spawned.
 610  *
 611  * MAX_CHILDREN should be a power-of-two to make the modulus
 612  * operation cheap. It should also be at least twice
 613  * the maximum number of connections we will ever allow.
 614  */
 615 #define MAX_CHILDREN 128
 616
 617 static int max_connections = 25;
 618
 619 /* These are updated by the signal handler */
 620 static volatile unsigned int children_reaped;
 621 static pid_t dead_child[MAX_CHILDREN];
 622
 623 /* These are updated by the main loop */
 624 static unsigned int children_spawned;
 625 static unsigned int children_deleted;
 626
 627 static struct child {
 628         pid_t pid;
 629         int addrlen;
 630         struct sockaddr_storage address;
 631 } live_child[MAX_CHILDREN];
 632
 633 static void add_child(int idx, pid_t pid, struct sockaddr *addr, int addrlen)
 634 {
 635         live_child[idx].pid = pid;
 636         live_child[idx].addrlen = addrlen;
 637         memcpy(&live_child[idx].address, addr, addrlen);
 638 }
 639
 640 /*
 641  * Walk from "deleted" to "spawned", and remove child "pid".
 642  *
 643  * We move everything up by one, since the new "deleted" will
 644  * be one higher.
 645  */
 646 static void remove_child(pid_t pid, unsigned deleted, unsigned spawned)
 647 {
 648         struct child n;
 649
 650         deleted %= MAX_CHILDREN;
 651         spawned %= MAX_CHILDREN;
 652         if (live_child[deleted].pid == pid) {
 653                 live_child[deleted].pid = -1;
 654                 return;
 655         }
 656         n = live_child[deleted];
 657         for (;;) {
 658                 struct child m;
 659                 deleted = (deleted + 1) % MAX_CHILDREN;
 660                 if (deleted == spawned)
 661                         die("could not find dead child %d\n", pid);
 662                 m = live_child[deleted];
 663                 live_child[deleted] = n;
 664                 if (m.pid == pid)
 665                         return;
 666                 n = m;
 667         }
 668 }
 669
 670 /*
 671  * This gets called if the number of connections grows
 672  * past "max_connections".
 673  *
 674  * We _should_ start off by searching for connections
 675  * from the same IP, and if there is some address wth
 676  * multiple connections, we should kill that first.
 677  *
 678  * As it is, we just "randomly" kill 25% of the connections,
 679  * and our pseudo-random generator sucks too. I have no
 680  * shame.
 681  *
 682  * Really, this is just a place-holder for a _real_ algorithm.
 683  */
 684 static void kill_some_children(int signo, unsigned start, unsigned stop)
 685 {
 686         start %= MAX_CHILDREN;
 687         stop %= MAX_CHILDREN;
 688         while (start != stop) {
 689                 if (!(start & 3))
 690                         kill(live_child[start].pid, signo);
 691                 start = (start + 1) % MAX_CHILDREN;
 692         }
 693 }
 694
 695 static void check_max_connections(void)
 696 {
 697         for (;;) {
 698                 int active;
 699                 unsigned spawned, reaped, deleted;
 700
 701                 spawned = children_spawned;
 702                 reaped = children_reaped;
 703                 deleted = children_deleted;
 704
 705                 while (deleted < reaped) {
 706                         pid_t pid = dead_child[deleted % MAX_CHILDREN];
 707                         remove_child(pid, deleted, spawned);
 708                         deleted++;
 709                 }
 710                 children_deleted = deleted;
 711
 712                 active = spawned - deleted;
 713                 if (active <= max_connections)
 714                         break;
 715
 716                 /* Kill some unstarted connections with SIGTERM */
 717                 kill_some_children(SIGTERM, deleted, spawned);
 718                 if (active <= max_connections << 1)
 719                         break;
 720
 721                 /* If the SIGTERM thing isn't helping use SIGKILL */
 722                 kill_some_children(SIGKILL, deleted, spawned);
 723                 sleep(1);
 724         }
 725 }
 726
 727 static void handle(int incoming, struct sockaddr *addr, int addrlen)
 728 {
 729         pid_t pid = fork();
 730
 731         if (pid) {
 732                 unsigned idx;
 733
 734                 close(incoming);
 735                 if (pid < 0)
 736                         return;
 737
 738                 idx = children_spawned % MAX_CHILDREN;
 739                 children_spawned++;
 740                 add_child(idx, pid, addr, addrlen);
 741
 742                 check_max_connections();
 743                 return;
 744         }
 745
 746         dup2(incoming, 0);
 747         dup2(incoming, 1);
 748         close(incoming);
 749
 750         exit(execute(addr));
 751 }
 752
 753 static void child_handler(int signo)
 754 {
 755         for (;;) {
 756                 int status;
 757                 pid_t pid = waitpid(-1, &status, WNOHANG);
 758
 759                 if (pid > 0) {
 760                         unsigned reaped = children_reaped;
 761                         dead_child[reaped % MAX_CHILDREN] = pid;
 762                         children_reaped = reaped + 1;
 763                         /* XXX: Custom logging, since we don't wanna getpid() */
 764                         if (verbose) {
 765                                 const char *dead = "";
 766                                 if (!WIFEXITED(status) || WEXITSTATUS(status) > 0)
 767                                         dead = " (with error)";
 768                                 if (log_syslog)
 769                                         syslog(LOG_INFO, "[%d] Disconnected%s", pid, dead);
 770                                 else
 771                                         fprintf(stderr, "[%d] Disconnected%s\n", pid, dead);
 772                         }
 773                         continue;
 774                 }
 775                 break;
 776         }
 777 }
 778
 779 static int set_reuse_addr(int sockfd)
 780 {
 781         int on = 1;
 782
 783         if (!reuseaddr)
 784                 return 0;
 785         return setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
 786                           &on, sizeof(on));
 787 }
 788
 789 #ifndef NO_IPV6
 790
 791 static int socksetup(char *listen_addr, int listen_port, int **socklist_p)
 792 {
 793         int socknum = 0, *socklist = NULL;
 794         int maxfd = -1;
 795         char pbuf[NI_MAXSERV];
 796         struct addrinfo hints, *ai0, *ai;
 797         int gai;
 798         long flags;
 799
 800         sprintf(pbuf, "%d", listen_port);
 801         memset(&hints, 0, sizeof(hints));
 802         hints.ai_family = AF_UNSPEC;
 803         hints.ai_socktype = SOCK_STREAM;
 804         hints.ai_protocol = IPPROTO_TCP;
 805         hints.ai_flags = AI_PASSIVE;
 806
 807         gai = getaddrinfo(listen_addr, pbuf, &hints, &ai0);
 808         if (gai)
 809                 die("getaddrinfo() failed: %s\n", gai_strerror(gai));
 810
 811         for (ai = ai0; ai; ai = ai->ai_next) {
 812                 int sockfd;
 813
 814                 sockfd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
 815                 if (sockfd < 0)
 816                         continue;
 817                 if (sockfd >= FD_SETSIZE) {
 818                         error("too large socket descriptor.");
 819                         close(sockfd);
 820                         continue;
 821                 }
 822
 823 #ifdef IPV6_V6ONLY
 824                 if (ai->ai_family == AF_INET6) {
 825                         int on = 1;
 826                         setsockopt(sockfd, IPPROTO_IPV6, IPV6_V6ONLY,
 827                                    &on, sizeof(on));
 828                         /* Note: error is not fatal */
 829                 }
 830 #endif
 831
 832                 if (set_reuse_addr(sockfd)) {
 833                         close(sockfd);
 834                         continue;
 835                 }
 836
 837                 if (bind(sockfd, ai->ai_addr, ai->ai_addrlen) < 0) {
 838                         close(sockfd);
 839                         continue;       /* not fatal */
 840                 }
 841                 if (listen(sockfd, 5) < 0) {
 842                         close(sockfd);
 843                         continue;       /* not fatal */
 844                 }
 845
 846                 flags = fcntl(sockfd, F_GETFD, 0);
 847                 if (flags >= 0)
 848                         fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
 849
 850                 socklist = xrealloc(socklist, sizeof(int) * (socknum + 1));
 851                 socklist[socknum++] = sockfd;
 852
 853                 if (maxfd < sockfd)
 854                         maxfd = sockfd;
 855         }
 856
 857         freeaddrinfo(ai0);
 858
 859         *socklist_p = socklist;
 860         return socknum;
 861 }
 862
 863 #else /* NO_IPV6 */
 864
 865 static int socksetup(char *listen_addr, int listen_port, int **socklist_p)
 866 {
 867         struct sockaddr_in sin;
 868         int sockfd;
 869         long flags;
 870
 871         memset(&sin, 0, sizeof sin);
 872         sin.sin_family = AF_INET;
 873         sin.sin_port = htons(listen_port);
 874
 875         if (listen_addr) {
 876                 /* Well, host better be an IP address here. */
 877                 if (inet_pton(AF_INET, listen_addr, &sin.sin_addr.s_addr) <= 0)
 878                         return 0;
 879         } else {
 880                 sin.sin_addr.s_addr = htonl(INADDR_ANY);
 881         }
 882
 883         sockfd = socket(AF_INET, SOCK_STREAM, 0);
 884         if (sockfd < 0)
 885                 return 0;
 886
 887         if (set_reuse_addr(sockfd)) {
 888                 close(sockfd);
 889                 return 0;
 890         }
 891
 892         if ( bind(sockfd, (struct sockaddr *)&sin, sizeof sin) < 0 ) {
 893                 close(sockfd);
 894                 return 0;
 895         }
 896
 897         if (listen(sockfd, 5) < 0) {
 898                 close(sockfd);
 899                 return 0;
 900         }
 901
 902         flags = fcntl(sockfd, F_GETFD, 0);
 903         if (flags >= 0)
 904                 fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
 905
 906         *socklist_p = xmalloc(sizeof(int));
 907         **socklist_p = sockfd;
 908         return 1;
 909 }
 910
 911 #endif
 912
 913 static int service_loop(int socknum, int *socklist)
 914 {
 915         struct pollfd *pfd;
 916         int i;
 917
 918         pfd = xcalloc(socknum, sizeof(struct pollfd));
 919
 920         for (i = 0; i < socknum; i++) {
 921                 pfd[i].fd = socklist[i];
 922                 pfd[i].events = POLLIN;
 923         }
 924
 925         signal(SIGCHLD, child_handler);
 926
 927         for (;;) {
 928                 int i;
 929
 930                 if (poll(pfd, socknum, -1) < 0) {
 931                         if (errno != EINTR) {
 932                                 error("poll failed, resuming: %s",
 933                                       strerror(errno));
 934                                 sleep(1);
 935                         }
 936                         continue;
 937                 }
 938
 939                 for (i = 0; i < socknum; i++) {
 940                         if (pfd[i].revents & POLLIN) {
 941                                 struct sockaddr_storage ss;
 942                                 unsigned int sslen = sizeof(ss);
 943                                 int incoming = accept(pfd[i].fd, (struct sockaddr *)&ss, &sslen);
 944                                 if (incoming < 0) {
 945                                         switch (errno) {
 946                                         case EAGAIN:
 947                                         case EINTR:
 948                                         case ECONNABORTED:
 949                                                 continue;
 950                                         default:
 951                                                 die("accept returned %s", strerror(errno));
 952                                         }
 953                                 }
 954                                 handle(incoming, (struct sockaddr *)&ss, sslen);
 955                         }
 956                 }
 957         }
 958 }
 959
 960 /* if any standard file descriptor is missing open it to /dev/null */
 961 static void sanitize_stdfds(void)
 962 {
 963         int fd = open("/dev/null", O_RDWR, 0);
 964         while (fd != -1 && fd < 2)
 965                 fd = dup(fd);
 966         if (fd == -1)
 967                 die("open /dev/null or dup failed: %s", strerror(errno));
 968         if (fd > 2)
 969                 close(fd);
 970 }
 971
 972 static void daemonize(void)
 973 {
 974         switch (fork()) {
 975                 case 0:
 976                         break;
 977                 case -1:
 978                         die("fork failed: %s", strerror(errno));
 979                 default:
 980                         exit(0);
 981         }
 982         if (setsid() == -1)
 983                 die("setsid failed: %s", strerror(errno));
 984         close(0);
 985         close(1);
 986         close(2);
 987         sanitize_stdfds();
 988 }
 989
 990 static void store_pid(const char *path)
 991 {
 992         FILE *f = fopen(path, "w");
 993         if (!f)
 994                 die("cannot open pid file %s: %s", path, strerror(errno));
 995         if (fprintf(f, "%d\n", getpid()) < 0 || fclose(f) != 0)
 996                 die("failed to write pid file %s: %s", path, strerror(errno));
 997 }
 998
 999 static int serve(char *listen_addr, int listen_port, struct passwd *pass, gid_t gid)
1000 {
1001         int socknum, *socklist;
1002
1003         socknum = socksetup(listen_addr, listen_port, &socklist);
1004         if (socknum == 0)
1005                 die("unable to allocate any listen sockets on host %s port %u",
1006                     listen_addr, listen_port);
1007
1008         if (pass && gid &&
1009             (initgroups(pass->pw_name, gid) || setgid (gid) ||
1010              setuid(pass->pw_uid)))
1011                 die("cannot drop privileges");
1012
1013         return service_loop(socknum, socklist);
1014 }
1015
1016 int main(int argc, char **argv)
1017 {
1018         int listen_port = 0;
1019         char *listen_addr = NULL;
1020         int inetd_mode = 0;
1021         const char *pid_file = NULL, *user_name = NULL, *group_name = NULL;
1022         int detach = 0;
1023         struct passwd *pass = NULL;
1024         struct group *group;
1025         gid_t gid = 0;
1026         int i;
1027
1028         /* Without this we cannot rely on waitpid() to tell
1029          * what happened to our children.
1030          */
1031         signal(SIGCHLD, SIG_DFL);
1032
1033         for (i = 1; i < argc; i++) {
1034                 char *arg = argv[i];
1035
1036                 if (!prefixcmp(arg, "--listen=")) {
1037                     char *p = arg + 9;
1038                     char *ph = listen_addr = xmalloc(strlen(arg + 9) + 1);
1039                     while (*p)
1040                         *ph++ = tolower(*p++);
1041                     *ph = 0;
1042                     continue;
1043                 }
1044                 if (!prefixcmp(arg, "--port=")) {
1045                         char *end;
1046                         unsigned long n;
1047                         n = strtoul(arg+7, &end, 0);
1048                         if (arg[7] && !*end) {
1049                                 listen_port = n;
1050                                 continue;
1051                         }
1052                 }
1053                 if (!strcmp(arg, "--inetd")) {
1054                         inetd_mode = 1;
1055                         log_syslog = 1;
1056                         continue;
1057                 }
1058                 if (!strcmp(arg, "--verbose")) {
1059                         verbose = 1;
1060                         continue;
1061                 }
1062                 if (!strcmp(arg, "--syslog")) {
1063                         log_syslog = 1;
1064                         continue;
1065                 }
1066                 if (!strcmp(arg, "--export-all")) {
1067                         export_all_trees = 1;
1068                         continue;
1069                 }
1070                 if (!prefixcmp(arg, "--timeout=")) {
1071                         timeout = atoi(arg+10);
1072                         continue;
1073                 }
1074                 if (!prefixcmp(arg, "--init-timeout=")) {
1075                         init_timeout = atoi(arg+15);
1076                         continue;
1077                 }
1078                 if (!strcmp(arg, "--strict-paths")) {
1079                         strict_paths = 1;
1080                         continue;
1081                 }
1082                 if (!prefixcmp(arg, "--base-path=")) {
1083                         base_path = arg+12;
1084                         continue;
1085                 }
1086                 if (!strcmp(arg, "--base-path-relaxed")) {
1087                         base_path_relaxed = 1;
1088                         continue;
1089                 }
1090                 if (!prefixcmp(arg, "--interpolated-path=")) {
1091                         interpolated_path = arg+20;
1092                         continue;
1093                 }
1094                 if (!strcmp(arg, "--reuseaddr")) {
1095                         reuseaddr = 1;
1096                         continue;
1097                 }
1098                 if (!strcmp(arg, "--user-path")) {
1099                         user_path = "";
1100                         continue;
1101                 }
1102                 if (!prefixcmp(arg, "--user-path=")) {
1103                         user_path = arg + 12;
1104                         continue;
1105                 }
1106                 if (!prefixcmp(arg, "--pid-file=")) {
1107                         pid_file = arg + 11;
1108                         continue;
1109                 }
1110                 if (!strcmp(arg, "--detach")) {
1111                         detach = 1;
1112                         log_syslog = 1;
1113                         continue;
1114                 }
1115                 if (!prefixcmp(arg, "--user=")) {
1116                         user_name = arg + 7;
1117                         continue;
1118                 }
1119                 if (!prefixcmp(arg, "--group=")) {
1120                         group_name = arg + 8;
1121                         continue;
1122                 }
1123                 if (!prefixcmp(arg, "--enable=")) {
1124                         enable_service(arg + 9, 1);
1125                         continue;
1126                 }
1127                 if (!prefixcmp(arg, "--disable=")) {
1128                         enable_service(arg + 10, 0);
1129                         continue;
1130                 }
1131                 if (!prefixcmp(arg, "--allow-override=")) {
1132                         make_service_overridable(arg + 17, 1);
1133                         continue;
1134                 }
1135                 if (!prefixcmp(arg, "--forbid-override=")) {
1136                         make_service_overridable(arg + 18, 0);
1137                         continue;
1138                 }
1139                 if (!strcmp(arg, "--")) {
1140                         ok_paths = &argv[i+1];
1141                         break;
1142                 } else if (arg[0] != '-') {
1143                         ok_paths = &argv[i];
1144                         break;
1145                 }
1146
1147                 usage(daemon_usage);
1148         }
1149
1150         if (inetd_mode && (group_name || user_name))
1151                 die("--user and --group are incompatible with --inetd");
1152
1153         if (inetd_mode && (listen_port || listen_addr))
1154                 die("--listen= and --port= are incompatible with --inetd");
1155         else if (listen_port == 0)
1156                 listen_port = DEFAULT_GIT_PORT;
1157
1158         if (group_name && !user_name)
1159                 die("--group supplied without --user");
1160
1161         if (user_name) {
1162                 pass = getpwnam(user_name);
1163                 if (!pass)
1164                         die("user not found - %s", user_name);
1165
1166                 if (!group_name)
1167                         gid = pass->pw_gid;
1168                 else {
1169                         group = getgrnam(group_name);
1170                         if (!group)
1171                                 die("group not found - %s", group_name);
1172
1173                         gid = group->gr_gid;
1174                 }
1175         }
1176
1177         if (log_syslog) {
1178                 openlog("git-daemon", 0, LOG_DAEMON);
1179                 set_die_routine(daemon_die);
1180         }
1181
1182         if (strict_paths && (!ok_paths || !*ok_paths))
1183                 die("option --strict-paths requires a whitelist");
1184
1185         if (inetd_mode) {
1186                 struct sockaddr_storage ss;
1187                 struct sockaddr *peer = (struct sockaddr *)&ss;
1188                 socklen_t slen = sizeof(ss);
1189
1190                 freopen("/dev/null", "w", stderr);
1191
1192                 if (getpeername(0, peer, &slen))
1193                         peer = NULL;
1194
1195                 return execute(peer);
1196         }
1197
1198         if (detach)
1199                 daemonize();
1200         else
1201                 sanitize_stdfds();
1202
1203         if (pid_file)
1204                 store_pid(pid_file);
1205
1206         return serve(listen_addr, listen_port, pass, gid);
1207 }