git.oblomov.eu Git - git/blob - 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 static int child_handler_pipe[2];
  20
  21 static const char daemon_usage[] =
  22 "git daemon [--verbose] [--syslog] [--export-all]\n"
  23 "           [--timeout=n] [--init-timeout=n] [--strict-paths]\n"
  24 "           [--base-path=path] [--base-path-relaxed]\n"
  25 "           [--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 static int base_path_relaxed;
  44
  45 /* Flag indicating client sent extra args. */
  46 static int saw_extended_args;
  47
  48 /* If defined, ~user notation is allowed and the string is inserted
  49  * after ~user/.  E.g. a request to git://host/~alice/frotz would
  50  * go to /home/alice/pub_git/frotz with --user-path=pub_git.
  51  */
  52 static const char *user_path;
  53
  54 /* Timeout, and initial timeout */
  55 static unsigned int timeout;
  56 static unsigned int init_timeout;
  57
  58 /*
  59  * Static table for now.  Ugh.
  60  * Feel free to make dynamic as needed.
  61  */
  62 #define INTERP_SLOT_HOST        (0)
  63 #define INTERP_SLOT_CANON_HOST  (1)
  64 #define INTERP_SLOT_IP          (2)
  65 #define INTERP_SLOT_PORT        (3)
  66 #define INTERP_SLOT_DIR         (4)
  67 #define INTERP_SLOT_PERCENT     (5)
  68
  69 static struct interp interp_table[] = {
  70         { "%H", 0},
  71         { "%CH", 0},
  72         { "%IP", 0},
  73         { "%P", 0},
  74         { "%D", 0},
  75         { "%%", 0},
  76 };
  77
  78
  79 static void logreport(int priority, const char *err, va_list params)
  80 {
  81         if (log_syslog) {
  82                 char buf[1024];
  83                 vsnprintf(buf, sizeof(buf), err, params);
  84                 syslog(priority, "%s", buf);
  85         }
  86         else {
  87                 /* Since stderr is set to linebuffered mode, the
  88                  * logging of different processes will not overlap
  89                  */
  90                 fprintf(stderr, "[%d] ", (int)getpid());
  91                 vfprintf(stderr, err, params);
  92                 fputc('\n', stderr);
  93         }
  94 }
  95
  96 static void logerror(const char *err, ...)
  97 {
  98         va_list params;
  99         va_start(params, err);
 100         logreport(LOG_ERR, err, params);
 101         va_end(params);
 102 }
 103
 104 static void loginfo(const char *err, ...)
 105 {
 106         va_list params;
 107         if (!verbose)
 108                 return;
 109         va_start(params, err);
 110         logreport(LOG_INFO, err, params);
 111         va_end(params);
 112 }
 113
 114 static void NORETURN daemon_die(const char *err, va_list params)
 115 {
 116         logreport(LOG_ERR, err, params);
 117         exit(1);
 118 }
 119
 120 static int avoid_alias(char *p)
 121 {
 122         int sl, ndot;
 123
 124         /*
 125          * This resurrects the belts and suspenders paranoia check by HPA
 126          * done in <435560F7.4080006@zytor.com> thread, now enter_repo()
 127          * does not do getcwd() based path canonicalizations.
 128          *
 129          * sl becomes true immediately after seeing '/' and continues to
 130          * be true as long as dots continue after that without intervening
 131          * non-dot character.
 132          */
 133         if (!p || (*p != '/' && *p != '~'))
 134                 return -1;
 135         sl = 1; ndot = 0;
 136         p++;
 137
 138         while (1) {
 139                 char ch = *p++;
 140                 if (sl) {
 141                         if (ch == '.')
 142                                 ndot++;
 143                         else if (ch == '/') {
 144                                 if (ndot < 3)
 145                                         /* reject //, /./ and /../ */
 146                                         return -1;
 147                                 ndot = 0;
 148                         }
 149                         else if (ch == 0) {
 150                                 if (0 < ndot && ndot < 3)
 151                                         /* reject /.$ and /..$ */
 152                                         return -1;
 153                                 return 0;
 154                         }
 155                         else
 156                                 sl = ndot = 0;
 157                 }
 158                 else if (ch == 0)
 159                         return 0;
 160                 else if (ch == '/') {
 161                         sl = 1;
 162                         ndot = 0;
 163                 }
 164         }
 165 }
 166
 167 static char *path_ok(struct interp *itable)
 168 {
 169         static char rpath[PATH_MAX];
 170         static char interp_path[PATH_MAX];
 171         int retried_path = 0;
 172         char *path;
 173         char *dir;
 174
 175         dir = itable[INTERP_SLOT_DIR].value;
 176
 177         if (avoid_alias(dir)) {
 178                 logerror("'%s': aliased", dir);
 179                 return NULL;
 180         }
 181
 182         if (*dir == '~') {
 183                 if (!user_path) {
 184                         logerror("'%s': User-path not allowed", dir);
 185                         return NULL;
 186                 }
 187                 if (*user_path) {
 188                         /* Got either "~alice" or "~alice/foo";
 189                          * rewrite them to "~alice/%s" or
 190                          * "~alice/%s/foo".
 191                          */
 192                         int namlen, restlen = strlen(dir);
 193                         char *slash = strchr(dir, '/');
 194                         if (!slash)
 195                                 slash = dir + restlen;
 196                         namlen = slash - dir;
 197                         restlen -= namlen;
 198                         loginfo("userpath <%s>, request <%s>, namlen %d, restlen %d, slash <%s>", user_path, dir, namlen, restlen, slash);
 199                         snprintf(rpath, PATH_MAX, "%.*s/%s%.*s",
 200                                  namlen, dir, user_path, restlen, slash);
 201                         dir = rpath;
 202                 }
 203         }
 204         else if (interpolated_path && saw_extended_args) {
 205                 if (*dir != '/') {
 206                         /* Allow only absolute */
 207                         logerror("'%s': Non-absolute path denied (interpolated-path active)", dir);
 208                         return NULL;
 209                 }
 210
 211                 interpolate(interp_path, PATH_MAX, interpolated_path,
 212                             interp_table, ARRAY_SIZE(interp_table));
 213                 loginfo("Interpolated dir '%s'", interp_path);
 214
 215                 dir = interp_path;
 216         }
 217         else if (base_path) {
 218                 if (*dir != '/') {
 219                         /* Allow only absolute */
 220                         logerror("'%s': Non-absolute path denied (base-path active)", dir);
 221                         return NULL;
 222                 }
 223                 snprintf(rpath, PATH_MAX, "%s%s", base_path, dir);
 224                 dir = rpath;
 225         }
 226
 227         do {
 228                 path = enter_repo(dir, strict_paths);
 229                 if (path)
 230                         break;
 231
 232                 /*
 233                  * if we fail and base_path_relaxed is enabled, try without
 234                  * prefixing the base path
 235                  */
 236                 if (base_path && base_path_relaxed && !retried_path) {
 237                         dir = itable[INTERP_SLOT_DIR].value;
 238                         retried_path = 1;
 239                         continue;
 240                 }
 241                 break;
 242         } while (1);
 243
 244         if (!path) {
 245                 logerror("'%s': unable to chdir or not a git archive", dir);
 246                 return NULL;
 247         }
 248
 249         if ( ok_paths && *ok_paths ) {
 250                 char **pp;
 251                 int pathlen = strlen(path);
 252
 253                 /* The validation is done on the paths after enter_repo
 254                  * appends optional {.git,.git/.git} and friends, but
 255                  * it does not use getcwd().  So if your /pub is
 256                  * a symlink to /mnt/pub, you can whitelist /pub and
 257                  * do not have to say /mnt/pub.
 258                  * Do not say /pub/.
 259                  */
 260                 for ( pp = ok_paths ; *pp ; pp++ ) {
 261                         int len = strlen(*pp);
 262                         if (len <= pathlen &&
 263                             !memcmp(*pp, path, len) &&
 264                             (path[len] == '\0' ||
 265                              (!strict_paths && path[len] == '/')))
 266                                 return path;
 267                 }
 268         }
 269         else {
 270                 /* be backwards compatible */
 271                 if (!strict_paths)
 272                         return path;
 273         }
 274
 275         logerror("'%s': not in whitelist", path);
 276         return NULL;            /* Fallthrough. Deny by default */
 277 }
 278
 279 typedef int (*daemon_service_fn)(void);
 280 struct daemon_service {
 281         const char *name;
 282         const char *config_name;
 283         daemon_service_fn fn;
 284         int enabled;
 285         int overridable;
 286 };
 287
 288 static struct daemon_service *service_looking_at;
 289 static int service_enabled;
 290
 291 static int git_daemon_config(const char *var, const char *value, void *cb)
 292 {
 293         if (!prefixcmp(var, "daemon.") &&
 294             !strcmp(var + 7, service_looking_at->config_name)) {
 295                 service_enabled = git_config_bool(var, value);
 296                 return 0;
 297         }
 298
 299         /* we are not interested in parsing any other configuration here */
 300         return 0;
 301 }
 302
 303 static int run_service(struct interp *itable, struct daemon_service *service)
 304 {
 305         const char *path;
 306         int enabled = service->enabled;
 307
 308         loginfo("Request %s for '%s'",
 309                 service->name,
 310                 itable[INTERP_SLOT_DIR].value);
 311
 312         if (!enabled && !service->overridable) {
 313                 logerror("'%s': service not enabled.", service->name);
 314                 errno = EACCES;
 315                 return -1;
 316         }
 317
 318         if (!(path = path_ok(itable)))
 319                 return -1;
 320
 321         /*
 322          * Security on the cheap.
 323          *
 324          * We want a readable HEAD, usable "objects" directory, and
 325          * a "git-daemon-export-ok" flag that says that the other side
 326          * is ok with us doing this.
 327          *
 328          * path_ok() uses enter_repo() and does whitelist checking.
 329          * We only need to make sure the repository is exported.
 330          */
 331
 332         if (!export_all_trees && access("git-daemon-export-ok", F_OK)) {
 333                 logerror("'%s': repository not exported.", path);
 334                 errno = EACCES;
 335                 return -1;
 336         }
 337
 338         if (service->overridable) {
 339                 service_looking_at = service;
 340                 service_enabled = -1;
 341                 git_config(git_daemon_config, NULL);
 342                 if (0 <= service_enabled)
 343                         enabled = service_enabled;
 344         }
 345         if (!enabled) {
 346                 logerror("'%s': service not enabled for '%s'",
 347                          service->name, path);
 348                 errno = EACCES;
 349                 return -1;
 350         }
 351
 352         /*
 353          * We'll ignore SIGTERM from now on, we have a
 354          * good client.
 355          */
 356         signal(SIGTERM, SIG_IGN);
 357
 358         return service->fn();
 359 }
 360
 361 static int upload_pack(void)
 362 {
 363         /* Timeout as string */
 364         char timeout_buf[64];
 365
 366         snprintf(timeout_buf, sizeof timeout_buf, "--timeout=%u", timeout);
 367
 368         /* git-upload-pack only ever reads stuff, so this is safe */
 369         execl_git_cmd("upload-pack", "--strict", timeout_buf, ".", NULL);
 370         return -1;
 371 }
 372
 373 static int upload_archive(void)
 374 {
 375         execl_git_cmd("upload-archive", ".", NULL);
 376         return -1;
 377 }
 378
 379 static int receive_pack(void)
 380 {
 381         execl_git_cmd("receive-pack", ".", 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         { "receive-pack", "receivepack", receive_pack, 0, 1 },
 389 };
 390
 391 static void enable_service(const char *name, int ena)
 392 {
 393         int i;
 394         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 395                 if (!strcmp(daemon_service[i].name, name)) {
 396                         daemon_service[i].enabled = ena;
 397                         return;
 398                 }
 399         }
 400         die("No such service %s", name);
 401 }
 402
 403 static void make_service_overridable(const char *name, int ena)
 404 {
 405         int i;
 406         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 407                 if (!strcmp(daemon_service[i].name, name)) {
 408                         daemon_service[i].overridable = ena;
 409                         return;
 410                 }
 411         }
 412         die("No such service %s", name);
 413 }
 414
 415 /*
 416  * Separate the "extra args" information as supplied by the client connection.
 417  * Any resulting data is squirreled away in the given interpolation table.
 418  */
 419 static void parse_extra_args(struct interp *table, char *extra_args, int buflen)
 420 {
 421         char *val;
 422         int vallen;
 423         char *end = extra_args + buflen;
 424
 425         while (extra_args < end && *extra_args) {
 426                 saw_extended_args = 1;
 427                 if (strncasecmp("host=", extra_args, 5) == 0) {
 428                         val = extra_args + 5;
 429                         vallen = strlen(val) + 1;
 430                         if (*val) {
 431                                 /* Split <host>:<port> at colon. */
 432                                 char *host = val;
 433                                 char *port = strrchr(host, ':');
 434                                 if (port) {
 435                                         *port = 0;
 436                                         port++;
 437                                         interp_set_entry(table, INTERP_SLOT_PORT, port);
 438                                 }
 439                                 interp_set_entry(table, INTERP_SLOT_HOST, host);
 440                         }
 441
 442                         /* On to the next one */
 443                         extra_args = val + vallen;
 444                 }
 445         }
 446 }
 447
 448 static void fill_in_extra_table_entries(struct interp *itable)
 449 {
 450         char *hp;
 451
 452         /*
 453          * Replace literal host with lowercase-ized hostname.
 454          */
 455         hp = interp_table[INTERP_SLOT_HOST].value;
 456         if (!hp)
 457                 return;
 458         for ( ; *hp; hp++)
 459                 *hp = tolower(*hp);
 460
 461         /*
 462          * Locate canonical hostname and its IP address.
 463          */
 464 #ifndef NO_IPV6
 465         {
 466                 struct addrinfo hints;
 467                 struct addrinfo *ai, *ai0;
 468                 int gai;
 469                 static char addrbuf[HOST_NAME_MAX + 1];
 470
 471                 memset(&hints, 0, sizeof(hints));
 472                 hints.ai_flags = AI_CANONNAME;
 473
 474                 gai = getaddrinfo(interp_table[INTERP_SLOT_HOST].value, 0, &hints, &ai0);
 475                 if (!gai) {
 476                         for (ai = ai0; ai; ai = ai->ai_next) {
 477                                 struct sockaddr_in *sin_addr = (void *)ai->ai_addr;
 478
 479                                 inet_ntop(AF_INET, &sin_addr->sin_addr,
 480                                           addrbuf, sizeof(addrbuf));
 481                                 interp_set_entry(interp_table,
 482                                                  INTERP_SLOT_CANON_HOST, ai->ai_canonname);
 483                                 interp_set_entry(interp_table,
 484                                                  INTERP_SLOT_IP, addrbuf);
 485                                 break;
 486                         }
 487                         freeaddrinfo(ai0);
 488                 }
 489         }
 490 #else
 491         {
 492                 struct hostent *hent;
 493                 struct sockaddr_in sa;
 494                 char **ap;
 495                 static char addrbuf[HOST_NAME_MAX + 1];
 496
 497                 hent = gethostbyname(interp_table[INTERP_SLOT_HOST].value);
 498
 499                 ap = hent->h_addr_list;
 500                 memset(&sa, 0, sizeof sa);
 501                 sa.sin_family = hent->h_addrtype;
 502                 sa.sin_port = htons(0);
 503                 memcpy(&sa.sin_addr, *ap, hent->h_length);
 504
 505                 inet_ntop(hent->h_addrtype, &sa.sin_addr,
 506                           addrbuf, sizeof(addrbuf));
 507
 508                 interp_set_entry(interp_table, INTERP_SLOT_CANON_HOST, hent->h_name);
 509                 interp_set_entry(interp_table, INTERP_SLOT_IP, addrbuf);
 510         }
 511 #endif
 512 }
 513
 514
 515 static int execute(struct sockaddr *addr)
 516 {
 517         static char line[1000];
 518         int pktlen, len, i;
 519
 520         if (addr) {
 521                 char addrbuf[256] = "";
 522                 int port = -1;
 523
 524                 if (addr->sa_family == AF_INET) {
 525                         struct sockaddr_in *sin_addr = (void *) addr;
 526                         inet_ntop(addr->sa_family, &sin_addr->sin_addr, addrbuf, sizeof(addrbuf));
 527                         port = ntohs(sin_addr->sin_port);
 528 #ifndef NO_IPV6
 529                 } else if (addr && addr->sa_family == AF_INET6) {
 530                         struct sockaddr_in6 *sin6_addr = (void *) addr;
 531
 532                         char *buf = addrbuf;
 533                         *buf++ = '['; *buf = '\0'; /* stpcpy() is cool */
 534                         inet_ntop(AF_INET6, &sin6_addr->sin6_addr, buf, sizeof(addrbuf) - 1);
 535                         strcat(buf, "]");
 536
 537                         port = ntohs(sin6_addr->sin6_port);
 538 #endif
 539                 }
 540                 loginfo("Connection from %s:%d", addrbuf, port);
 541         }
 542
 543         alarm(init_timeout ? init_timeout : timeout);
 544         pktlen = packet_read_line(0, line, sizeof(line));
 545         alarm(0);
 546
 547         len = strlen(line);
 548         if (pktlen != len)
 549                 loginfo("Extended attributes (%d bytes) exist <%.*s>",
 550                         (int) pktlen - len,
 551                         (int) pktlen - len, line + len + 1);
 552         if (len && line[len-1] == '\n') {
 553                 line[--len] = 0;
 554                 pktlen--;
 555         }
 556
 557         /*
 558          * Initialize the path interpolation table for this connection.
 559          */
 560         interp_clear_table(interp_table, ARRAY_SIZE(interp_table));
 561         interp_set_entry(interp_table, INTERP_SLOT_PERCENT, "%");
 562
 563         if (len != pktlen) {
 564             parse_extra_args(interp_table, line + len + 1, pktlen - len - 1);
 565             fill_in_extra_table_entries(interp_table);
 566         }
 567
 568         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 569                 struct daemon_service *s = &(daemon_service[i]);
 570                 int namelen = strlen(s->name);
 571                 if (!prefixcmp(line, "git-") &&
 572                     !strncmp(s->name, line + 4, namelen) &&
 573                     line[namelen + 4] == ' ') {
 574                         /*
 575                          * Note: The directory here is probably context sensitive,
 576                          * and might depend on the actual service being performed.
 577                          */
 578                         interp_set_entry(interp_table,
 579                                          INTERP_SLOT_DIR, line + namelen + 5);
 580                         return run_service(interp_table, s);
 581                 }
 582         }
 583
 584         logerror("Protocol error: '%s'", line);
 585         return -1;
 586 }
 587
 588
 589 /*
 590  * We count spawned/reaped separately, just to avoid any
 591  * races when updating them from signals. The SIGCHLD handler
 592  * will only update children_reaped, and the fork logic will
 593  * only update children_spawned.
 594  *
 595  * MAX_CHILDREN should be a power-of-two to make the modulus
 596  * operation cheap. It should also be at least twice
 597  * the maximum number of connections we will ever allow.
 598  */
 599 #define MAX_CHILDREN 128
 600
 601 static int max_connections = 25;
 602
 603 /* These are updated by the signal handler */
 604 static volatile unsigned int children_reaped;
 605 static pid_t dead_child[MAX_CHILDREN];
 606
 607 /* These are updated by the main loop */
 608 static unsigned int children_spawned;
 609 static unsigned int children_deleted;
 610
 611 static struct child {
 612         pid_t pid;
 613         int addrlen;
 614         struct sockaddr_storage address;
 615 } live_child[MAX_CHILDREN];
 616
 617 static void add_child(int idx, pid_t pid, struct sockaddr *addr, int addrlen)
 618 {
 619         live_child[idx].pid = pid;
 620         live_child[idx].addrlen = addrlen;
 621         memcpy(&live_child[idx].address, addr, addrlen);
 622 }
 623
 624 /*
 625  * Walk from "deleted" to "spawned", and remove child "pid".
 626  *
 627  * We move everything up by one, since the new "deleted" will
 628  * be one higher.
 629  */
 630 static void remove_child(pid_t pid, unsigned deleted, unsigned spawned)
 631 {
 632         struct child n;
 633
 634         deleted %= MAX_CHILDREN;
 635         spawned %= MAX_CHILDREN;
 636         if (live_child[deleted].pid == pid) {
 637                 live_child[deleted].pid = -1;
 638                 return;
 639         }
 640         n = live_child[deleted];
 641         for (;;) {
 642                 struct child m;
 643                 deleted = (deleted + 1) % MAX_CHILDREN;
 644                 if (deleted == spawned)
 645                         die("could not find dead child %d\n", pid);
 646                 m = live_child[deleted];
 647                 live_child[deleted] = n;
 648                 if (m.pid == pid)
 649                         return;
 650                 n = m;
 651         }
 652 }
 653
 654 /*
 655  * This gets called if the number of connections grows
 656  * past "max_connections".
 657  *
 658  * We _should_ start off by searching for connections
 659  * from the same IP, and if there is some address wth
 660  * multiple connections, we should kill that first.
 661  *
 662  * As it is, we just "randomly" kill 25% of the connections,
 663  * and our pseudo-random generator sucks too. I have no
 664  * shame.
 665  *
 666  * Really, this is just a place-holder for a _real_ algorithm.
 667  */
 668 static void kill_some_children(int signo, unsigned start, unsigned stop)
 669 {
 670         start %= MAX_CHILDREN;
 671         stop %= MAX_CHILDREN;
 672         while (start != stop) {
 673                 if (!(start & 3))
 674                         kill(live_child[start].pid, signo);
 675                 start = (start + 1) % MAX_CHILDREN;
 676         }
 677 }
 678
 679 static void check_dead_children(void)
 680 {
 681         unsigned spawned, reaped, deleted;
 682
 683         spawned = children_spawned;
 684         reaped = children_reaped;
 685         deleted = children_deleted;
 686
 687         while (deleted < reaped) {
 688                 pid_t pid = dead_child[deleted % MAX_CHILDREN];
 689                 const char *dead = pid < 0 ? " (with error)" : "";
 690
 691                 if (pid < 0)
 692                         pid = -pid;
 693
 694                 /* XXX: Custom logging, since we don't wanna getpid() */
 695                 if (verbose) {
 696                         if (log_syslog)
 697                                 syslog(LOG_INFO, "[%d] Disconnected%s",
 698                                                 pid, dead);
 699                         else
 700                                 fprintf(stderr, "[%d] Disconnected%s\n",
 701                                                 pid, dead);
 702                 }
 703                 remove_child(pid, deleted, spawned);
 704                 deleted++;
 705         }
 706         children_deleted = deleted;
 707 }
 708
 709 static void check_max_connections(void)
 710 {
 711         for (;;) {
 712                 int active;
 713                 unsigned spawned, deleted;
 714
 715                 check_dead_children();
 716
 717                 spawned = children_spawned;
 718                 deleted = children_deleted;
 719
 720                 active = spawned - deleted;
 721                 if (active <= max_connections)
 722                         break;
 723
 724                 /* Kill some unstarted connections with SIGTERM */
 725                 kill_some_children(SIGTERM, deleted, spawned);
 726                 if (active <= max_connections << 1)
 727                         break;
 728
 729                 /* If the SIGTERM thing isn't helping use SIGKILL */
 730                 kill_some_children(SIGKILL, deleted, spawned);
 731                 sleep(1);
 732         }
 733 }
 734
 735 static void handle(int incoming, struct sockaddr *addr, int addrlen)
 736 {
 737         pid_t pid = fork();
 738
 739         if (pid) {
 740                 unsigned idx;
 741
 742                 close(incoming);
 743                 if (pid < 0)
 744                         return;
 745
 746                 idx = children_spawned % MAX_CHILDREN;
 747                 children_spawned++;
 748                 add_child(idx, pid, addr, addrlen);
 749
 750                 check_max_connections();
 751                 return;
 752         }
 753
 754         dup2(incoming, 0);
 755         dup2(incoming, 1);
 756         close(incoming);
 757
 758         exit(execute(addr));
 759 }
 760
 761 static void child_handler(int signo)
 762 {
 763         for (;;) {
 764                 int status;
 765                 pid_t pid = waitpid(-1, &status, WNOHANG);
 766
 767                 if (pid > 0) {
 768                         unsigned reaped = children_reaped;
 769                         if (!WIFEXITED(status) || WEXITSTATUS(status) > 0)
 770                                 pid = -pid;
 771                         dead_child[reaped % MAX_CHILDREN] = pid;
 772                         children_reaped = reaped + 1;
 773                         write(child_handler_pipe[1], &status, 1);
 774                         continue;
 775                 }
 776                 break;
 777         }
 778         signal(SIGCHLD, child_handler);
 779 }
 780
 781 static int set_reuse_addr(int sockfd)
 782 {
 783         int on = 1;
 784
 785         if (!reuseaddr)
 786                 return 0;
 787         return setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
 788                           &on, sizeof(on));
 789 }
 790
 791 #ifndef NO_IPV6
 792
 793 static int socksetup(char *listen_addr, int listen_port, int **socklist_p)
 794 {
 795         int socknum = 0, *socklist = NULL;
 796         int maxfd = -1;
 797         char pbuf[NI_MAXSERV];
 798         struct addrinfo hints, *ai0, *ai;
 799         int gai;
 800         long flags;
 801
 802         sprintf(pbuf, "%d", listen_port);
 803         memset(&hints, 0, sizeof(hints));
 804         hints.ai_family = AF_UNSPEC;
 805         hints.ai_socktype = SOCK_STREAM;
 806         hints.ai_protocol = IPPROTO_TCP;
 807         hints.ai_flags = AI_PASSIVE;
 808
 809         gai = getaddrinfo(listen_addr, pbuf, &hints, &ai0);
 810         if (gai)
 811                 die("getaddrinfo() failed: %s\n", gai_strerror(gai));
 812
 813         for (ai = ai0; ai; ai = ai->ai_next) {
 814                 int sockfd;
 815
 816                 sockfd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
 817                 if (sockfd < 0)
 818                         continue;
 819                 if (sockfd >= FD_SETSIZE) {
 820                         logerror("Socket descriptor too large");
 821                         close(sockfd);
 822                         continue;
 823                 }
 824
 825 #ifdef IPV6_V6ONLY
 826                 if (ai->ai_family == AF_INET6) {
 827                         int on = 1;
 828                         setsockopt(sockfd, IPPROTO_IPV6, IPV6_V6ONLY,
 829                                    &on, sizeof(on));
 830                         /* Note: error is not fatal */
 831                 }
 832 #endif
 833
 834                 if (set_reuse_addr(sockfd)) {
 835                         close(sockfd);
 836                         continue;
 837                 }
 838
 839                 if (bind(sockfd, ai->ai_addr, ai->ai_addrlen) < 0) {
 840                         close(sockfd);
 841                         continue;       /* not fatal */
 842                 }
 843                 if (listen(sockfd, 5) < 0) {
 844                         close(sockfd);
 845                         continue;       /* not fatal */
 846                 }
 847
 848                 flags = fcntl(sockfd, F_GETFD, 0);
 849                 if (flags >= 0)
 850                         fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
 851
 852                 socklist = xrealloc(socklist, sizeof(int) * (socknum + 1));
 853                 socklist[socknum++] = sockfd;
 854
 855                 if (maxfd < sockfd)
 856                         maxfd = sockfd;
 857         }
 858
 859         freeaddrinfo(ai0);
 860
 861         *socklist_p = socklist;
 862         return socknum;
 863 }
 864
 865 #else /* NO_IPV6 */
 866
 867 static int socksetup(char *listen_addr, int listen_port, int **socklist_p)
 868 {
 869         struct sockaddr_in sin;
 870         int sockfd;
 871         long flags;
 872
 873         memset(&sin, 0, sizeof sin);
 874         sin.sin_family = AF_INET;
 875         sin.sin_port = htons(listen_port);
 876
 877         if (listen_addr) {
 878                 /* Well, host better be an IP address here. */
 879                 if (inet_pton(AF_INET, listen_addr, &sin.sin_addr.s_addr) <= 0)
 880                         return 0;
 881         } else {
 882                 sin.sin_addr.s_addr = htonl(INADDR_ANY);
 883         }
 884
 885         sockfd = socket(AF_INET, SOCK_STREAM, 0);
 886         if (sockfd < 0)
 887                 return 0;
 888
 889         if (set_reuse_addr(sockfd)) {
 890                 close(sockfd);
 891                 return 0;
 892         }
 893
 894         if ( bind(sockfd, (struct sockaddr *)&sin, sizeof sin) < 0 ) {
 895                 close(sockfd);
 896                 return 0;
 897         }
 898
 899         if (listen(sockfd, 5) < 0) {
 900                 close(sockfd);
 901                 return 0;
 902         }
 903
 904         flags = fcntl(sockfd, F_GETFD, 0);
 905         if (flags >= 0)
 906                 fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
 907
 908         *socklist_p = xmalloc(sizeof(int));
 909         **socklist_p = sockfd;
 910         return 1;
 911 }
 912
 913 #endif
 914
 915 static int service_loop(int socknum, int *socklist)
 916 {
 917         struct pollfd *pfd;
 918         int i;
 919
 920         if (pipe(child_handler_pipe) < 0)
 921                 die ("Could not set up pipe for child handler");
 922
 923         pfd = xcalloc(socknum + 1, sizeof(struct pollfd));
 924
 925         for (i = 0; i < socknum; i++) {
 926                 pfd[i].fd = socklist[i];
 927                 pfd[i].events = POLLIN;
 928         }
 929         pfd[socknum].fd = child_handler_pipe[0];
 930         pfd[socknum].events = POLLIN;
 931
 932         signal(SIGCHLD, child_handler);
 933
 934         for (;;) {
 935                 int i;
 936
 937                 if (poll(pfd, socknum + 1, -1) < 0) {
 938                         if (errno != EINTR) {
 939                                 logerror("Poll failed, resuming: %s",
 940                                       strerror(errno));
 941                                 sleep(1);
 942                         }
 943                         continue;
 944                 }
 945                 if (pfd[socknum].revents & POLLIN) {
 946                         read(child_handler_pipe[0], &i, 1);
 947                         check_dead_children();
 948                 }
 949
 950                 for (i = 0; i < socknum; i++) {
 951                         if (pfd[i].revents & POLLIN) {
 952                                 struct sockaddr_storage ss;
 953                                 unsigned int sslen = sizeof(ss);
 954                                 int incoming = accept(pfd[i].fd, (struct sockaddr *)&ss, &sslen);
 955                                 if (incoming < 0) {
 956                                         switch (errno) {
 957                                         case EAGAIN:
 958                                         case EINTR:
 959                                         case ECONNABORTED:
 960                                                 continue;
 961                                         default:
 962                                                 die("accept returned %s", strerror(errno));
 963                                         }
 964                                 }
 965                                 handle(incoming, (struct sockaddr *)&ss, sslen);
 966                         }
 967                 }
 968         }
 969 }
 970
 971 /* if any standard file descriptor is missing open it to /dev/null */
 972 static void sanitize_stdfds(void)
 973 {
 974         int fd = open("/dev/null", O_RDWR, 0);
 975         while (fd != -1 && fd < 2)
 976                 fd = dup(fd);
 977         if (fd == -1)
 978                 die("open /dev/null or dup failed: %s", strerror(errno));
 979         if (fd > 2)
 980                 close(fd);
 981 }
 982
 983 static void daemonize(void)
 984 {
 985         switch (fork()) {
 986                 case 0:
 987                         break;
 988                 case -1:
 989                         die("fork failed: %s", strerror(errno));
 990                 default:
 991                         exit(0);
 992         }
 993         if (setsid() == -1)
 994                 die("setsid failed: %s", strerror(errno));
 995         close(0);
 996         close(1);
 997         close(2);
 998         sanitize_stdfds();
 999 }
1000
1001 static void store_pid(const char *path)
1002 {
1003         FILE *f = fopen(path, "w");
1004         if (!f)
1005                 die("cannot open pid file %s: %s", path, strerror(errno));
1006         if (fprintf(f, "%d\n", getpid()) < 0 || fclose(f) != 0)
1007                 die("failed to write pid file %s: %s", path, strerror(errno));
1008 }
1009
1010 static int serve(char *listen_addr, int listen_port, struct passwd *pass, gid_t gid)
1011 {
1012         int socknum, *socklist;
1013
1014         socknum = socksetup(listen_addr, listen_port, &socklist);
1015         if (socknum == 0)
1016                 die("unable to allocate any listen sockets on host %s port %u",
1017                     listen_addr, listen_port);
1018
1019         if (pass && gid &&
1020             (initgroups(pass->pw_name, gid) || setgid (gid) ||
1021              setuid(pass->pw_uid)))
1022                 die("cannot drop privileges");
1023
1024         return service_loop(socknum, socklist);
1025 }
1026
1027 int main(int argc, char **argv)
1028 {
1029         int listen_port = 0;
1030         char *listen_addr = NULL;
1031         int inetd_mode = 0;
1032         const char *pid_file = NULL, *user_name = NULL, *group_name = NULL;
1033         int detach = 0;
1034         struct passwd *pass = NULL;
1035         struct group *group;
1036         gid_t gid = 0;
1037         int i;
1038
1039         /* Without this we cannot rely on waitpid() to tell
1040          * what happened to our children.
1041          */
1042         signal(SIGCHLD, SIG_DFL);
1043
1044         for (i = 1; i < argc; i++) {
1045                 char *arg = argv[i];
1046
1047                 if (!prefixcmp(arg, "--listen=")) {
1048                     char *p = arg + 9;
1049                     char *ph = listen_addr = xmalloc(strlen(arg + 9) + 1);
1050                     while (*p)
1051                         *ph++ = tolower(*p++);
1052                     *ph = 0;
1053                     continue;
1054                 }
1055                 if (!prefixcmp(arg, "--port=")) {
1056                         char *end;
1057                         unsigned long n;
1058                         n = strtoul(arg+7, &end, 0);
1059                         if (arg[7] && !*end) {
1060                                 listen_port = n;
1061                                 continue;
1062                         }
1063                 }
1064                 if (!strcmp(arg, "--inetd")) {
1065                         inetd_mode = 1;
1066                         log_syslog = 1;
1067                         continue;
1068                 }
1069                 if (!strcmp(arg, "--verbose")) {
1070                         verbose = 1;
1071                         continue;
1072                 }
1073                 if (!strcmp(arg, "--syslog")) {
1074                         log_syslog = 1;
1075                         continue;
1076                 }
1077                 if (!strcmp(arg, "--export-all")) {
1078                         export_all_trees = 1;
1079                         continue;
1080                 }
1081                 if (!prefixcmp(arg, "--timeout=")) {
1082                         timeout = atoi(arg+10);
1083                         continue;
1084                 }
1085                 if (!prefixcmp(arg, "--init-timeout=")) {
1086                         init_timeout = atoi(arg+15);
1087                         continue;
1088                 }
1089                 if (!strcmp(arg, "--strict-paths")) {
1090                         strict_paths = 1;
1091                         continue;
1092                 }
1093                 if (!prefixcmp(arg, "--base-path=")) {
1094                         base_path = arg+12;
1095                         continue;
1096                 }
1097                 if (!strcmp(arg, "--base-path-relaxed")) {
1098                         base_path_relaxed = 1;
1099                         continue;
1100                 }
1101                 if (!prefixcmp(arg, "--interpolated-path=")) {
1102                         interpolated_path = arg+20;
1103                         continue;
1104                 }
1105                 if (!strcmp(arg, "--reuseaddr")) {
1106                         reuseaddr = 1;
1107                         continue;
1108                 }
1109                 if (!strcmp(arg, "--user-path")) {
1110                         user_path = "";
1111                         continue;
1112                 }
1113                 if (!prefixcmp(arg, "--user-path=")) {
1114                         user_path = arg + 12;
1115                         continue;
1116                 }
1117                 if (!prefixcmp(arg, "--pid-file=")) {
1118                         pid_file = arg + 11;
1119                         continue;
1120                 }
1121                 if (!strcmp(arg, "--detach")) {
1122                         detach = 1;
1123                         log_syslog = 1;
1124                         continue;
1125                 }
1126                 if (!prefixcmp(arg, "--user=")) {
1127                         user_name = arg + 7;
1128                         continue;
1129                 }
1130                 if (!prefixcmp(arg, "--group=")) {
1131                         group_name = arg + 8;
1132                         continue;
1133                 }
1134                 if (!prefixcmp(arg, "--enable=")) {
1135                         enable_service(arg + 9, 1);
1136                         continue;
1137                 }
1138                 if (!prefixcmp(arg, "--disable=")) {
1139                         enable_service(arg + 10, 0);
1140                         continue;
1141                 }
1142                 if (!prefixcmp(arg, "--allow-override=")) {
1143                         make_service_overridable(arg + 17, 1);
1144                         continue;
1145                 }
1146                 if (!prefixcmp(arg, "--forbid-override=")) {
1147                         make_service_overridable(arg + 18, 0);
1148                         continue;
1149                 }
1150                 if (!strcmp(arg, "--")) {
1151                         ok_paths = &argv[i+1];
1152                         break;
1153                 } else if (arg[0] != '-') {
1154                         ok_paths = &argv[i];
1155                         break;
1156                 }
1157
1158                 usage(daemon_usage);
1159         }
1160
1161         if (log_syslog) {
1162                 openlog("git-daemon", LOG_PID, LOG_DAEMON);
1163                 set_die_routine(daemon_die);
1164         }
1165         else
1166                 setlinebuf(stderr); /* avoid splitting a message in the middle */
1167
1168         if (inetd_mode && (group_name || user_name))
1169                 die("--user and --group are incompatible with --inetd");
1170
1171         if (inetd_mode && (listen_port || listen_addr))
1172                 die("--listen= and --port= are incompatible with --inetd");
1173         else if (listen_port == 0)
1174                 listen_port = DEFAULT_GIT_PORT;
1175
1176         if (group_name && !user_name)
1177                 die("--group supplied without --user");
1178
1179         if (user_name) {
1180                 pass = getpwnam(user_name);
1181                 if (!pass)
1182                         die("user not found - %s", user_name);
1183
1184                 if (!group_name)
1185                         gid = pass->pw_gid;
1186                 else {
1187                         group = getgrnam(group_name);
1188                         if (!group)
1189                                 die("group not found - %s", group_name);
1190
1191                         gid = group->gr_gid;
1192                 }
1193         }
1194
1195         if (strict_paths && (!ok_paths || !*ok_paths))
1196                 die("option --strict-paths requires a whitelist");
1197
1198         if (base_path) {
1199                 struct stat st;
1200
1201                 if (stat(base_path, &st) || !S_ISDIR(st.st_mode))
1202                         die("base-path '%s' does not exist or "
1203                             "is not a directory", base_path);
1204         }
1205
1206         if (inetd_mode) {
1207                 struct sockaddr_storage ss;
1208                 struct sockaddr *peer = (struct sockaddr *)&ss;
1209                 socklen_t slen = sizeof(ss);
1210
1211                 freopen("/dev/null", "w", stderr);
1212
1213                 if (getpeername(0, peer, &slen))
1214                         peer = NULL;
1215
1216                 return execute(peer);
1217         }
1218
1219         if (detach) {
1220                 daemonize();
1221                 loginfo("Ready to rumble");
1222         }
1223         else
1224                 sanitize_stdfds();
1225
1226         if (pid_file)
1227                 store_pid(pid_file);
1228
1229         return serve(listen_addr, listen_port, pass, gid);
1230 }