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
  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         if (log_syslog) {
  81                 char buf[1024];
  82                 vsnprintf(buf, sizeof(buf), err, params);
  83                 syslog(priority, "%s", buf);
  84         }
  85         else {
  86                 /* Since stderr is set to linebuffered mode, the
  87                  * logging of different processes will not overlap
  88                  */
  89                 fprintf(stderr, "[%d] ", (int)getpid());
  90                 vfprintf(stderr, err, params);
  91                 fputc('\n', stderr);
  92         }
  93 }
  94
  95 static void logerror(const char *err, ...)
  96 {
  97         va_list params;
  98         va_start(params, err);
  99         logreport(LOG_ERR, err, params);
 100         va_end(params);
 101 }
 102
 103 static void loginfo(const char *err, ...)
 104 {
 105         va_list params;
 106         if (!verbose)
 107                 return;
 108         va_start(params, err);
 109         logreport(LOG_INFO, err, params);
 110         va_end(params);
 111 }
 112
 113 static void NORETURN daemon_die(const char *err, va_list params)
 114 {
 115         logreport(LOG_ERR, err, params);
 116         exit(1);
 117 }
 118
 119 static int avoid_alias(char *p)
 120 {
 121         int sl, ndot;
 122
 123         /*
 124          * This resurrects the belts and suspenders paranoia check by HPA
 125          * done in <435560F7.4080006@zytor.com> thread, now enter_repo()
 126          * does not do getcwd() based path canonicalizations.
 127          *
 128          * sl becomes true immediately after seeing '/' and continues to
 129          * be true as long as dots continue after that without intervening
 130          * non-dot character.
 131          */
 132         if (!p || (*p != '/' && *p != '~'))
 133                 return -1;
 134         sl = 1; ndot = 0;
 135         p++;
 136
 137         while (1) {
 138                 char ch = *p++;
 139                 if (sl) {
 140                         if (ch == '.')
 141                                 ndot++;
 142                         else if (ch == '/') {
 143                                 if (ndot < 3)
 144                                         /* reject //, /./ and /../ */
 145                                         return -1;
 146                                 ndot = 0;
 147                         }
 148                         else if (ch == 0) {
 149                                 if (0 < ndot && ndot < 3)
 150                                         /* reject /.$ and /..$ */
 151                                         return -1;
 152                                 return 0;
 153                         }
 154                         else
 155                                 sl = ndot = 0;
 156                 }
 157                 else if (ch == 0)
 158                         return 0;
 159                 else if (ch == '/') {
 160                         sl = 1;
 161                         ndot = 0;
 162                 }
 163         }
 164 }
 165
 166 static char *path_ok(struct interp *itable)
 167 {
 168         static char rpath[PATH_MAX];
 169         static char interp_path[PATH_MAX];
 170         int retried_path = 0;
 171         char *path;
 172         char *dir;
 173
 174         dir = itable[INTERP_SLOT_DIR].value;
 175
 176         if (avoid_alias(dir)) {
 177                 logerror("'%s': aliased", dir);
 178                 return NULL;
 179         }
 180
 181         if (*dir == '~') {
 182                 if (!user_path) {
 183                         logerror("'%s': User-path not allowed", dir);
 184                         return NULL;
 185                 }
 186                 if (*user_path) {
 187                         /* Got either "~alice" or "~alice/foo";
 188                          * rewrite them to "~alice/%s" or
 189                          * "~alice/%s/foo".
 190                          */
 191                         int namlen, restlen = strlen(dir);
 192                         char *slash = strchr(dir, '/');
 193                         if (!slash)
 194                                 slash = dir + restlen;
 195                         namlen = slash - dir;
 196                         restlen -= namlen;
 197                         loginfo("userpath <%s>, request <%s>, namlen %d, restlen %d, slash <%s>", user_path, dir, namlen, restlen, slash);
 198                         snprintf(rpath, PATH_MAX, "%.*s/%s%.*s",
 199                                  namlen, dir, user_path, restlen, slash);
 200                         dir = rpath;
 201                 }
 202         }
 203         else if (interpolated_path && saw_extended_args) {
 204                 if (*dir != '/') {
 205                         /* Allow only absolute */
 206                         logerror("'%s': Non-absolute path denied (interpolated-path active)", dir);
 207                         return NULL;
 208                 }
 209
 210                 interpolate(interp_path, PATH_MAX, interpolated_path,
 211                             interp_table, ARRAY_SIZE(interp_table));
 212                 loginfo("Interpolated dir '%s'", interp_path);
 213
 214                 dir = interp_path;
 215         }
 216         else if (base_path) {
 217                 if (*dir != '/') {
 218                         /* Allow only absolute */
 219                         logerror("'%s': Non-absolute path denied (base-path active)", dir);
 220                         return NULL;
 221                 }
 222                 snprintf(rpath, PATH_MAX, "%s%s", base_path, dir);
 223                 dir = rpath;
 224         }
 225
 226         do {
 227                 path = enter_repo(dir, strict_paths);
 228                 if (path)
 229                         break;
 230
 231                 /*
 232                  * if we fail and base_path_relaxed is enabled, try without
 233                  * prefixing the base path
 234                  */
 235                 if (base_path && base_path_relaxed && !retried_path) {
 236                         dir = itable[INTERP_SLOT_DIR].value;
 237                         retried_path = 1;
 238                         continue;
 239                 }
 240                 break;
 241         } while (1);
 242
 243         if (!path) {
 244                 logerror("'%s': unable to chdir or not a git archive", dir);
 245                 return NULL;
 246         }
 247
 248         if ( ok_paths && *ok_paths ) {
 249                 char **pp;
 250                 int pathlen = strlen(path);
 251
 252                 /* The validation is done on the paths after enter_repo
 253                  * appends optional {.git,.git/.git} and friends, but
 254                  * it does not use getcwd().  So if your /pub is
 255                  * a symlink to /mnt/pub, you can whitelist /pub and
 256                  * do not have to say /mnt/pub.
 257                  * Do not say /pub/.
 258                  */
 259                 for ( pp = ok_paths ; *pp ; pp++ ) {
 260                         int len = strlen(*pp);
 261                         if (len <= pathlen &&
 262                             !memcmp(*pp, path, len) &&
 263                             (path[len] == '\0' ||
 264                              (!strict_paths && path[len] == '/')))
 265                                 return path;
 266                 }
 267         }
 268         else {
 269                 /* be backwards compatible */
 270                 if (!strict_paths)
 271                         return path;
 272         }
 273
 274         logerror("'%s': not in whitelist", path);
 275         return NULL;            /* Fallthrough. Deny by default */
 276 }
 277
 278 typedef int (*daemon_service_fn)(void);
 279 struct daemon_service {
 280         const char *name;
 281         const char *config_name;
 282         daemon_service_fn fn;
 283         int enabled;
 284         int overridable;
 285 };
 286
 287 static struct daemon_service *service_looking_at;
 288 static int service_enabled;
 289
 290 static int git_daemon_config(const char *var, const char *value, void *cb)
 291 {
 292         if (!prefixcmp(var, "daemon.") &&
 293             !strcmp(var + 7, service_looking_at->config_name)) {
 294                 service_enabled = git_config_bool(var, value);
 295                 return 0;
 296         }
 297
 298         /* we are not interested in parsing any other configuration here */
 299         return 0;
 300 }
 301
 302 static int run_service(struct interp *itable, struct daemon_service *service)
 303 {
 304         const char *path;
 305         int enabled = service->enabled;
 306
 307         loginfo("Request %s for '%s'",
 308                 service->name,
 309                 itable[INTERP_SLOT_DIR].value);
 310
 311         if (!enabled && !service->overridable) {
 312                 logerror("'%s': service not enabled.", service->name);
 313                 errno = EACCES;
 314                 return -1;
 315         }
 316
 317         if (!(path = path_ok(itable)))
 318                 return -1;
 319
 320         /*
 321          * Security on the cheap.
 322          *
 323          * We want a readable HEAD, usable "objects" directory, and
 324          * a "git-daemon-export-ok" flag that says that the other side
 325          * is ok with us doing this.
 326          *
 327          * path_ok() uses enter_repo() and does whitelist checking.
 328          * We only need to make sure the repository is exported.
 329          */
 330
 331         if (!export_all_trees && access("git-daemon-export-ok", F_OK)) {
 332                 logerror("'%s': repository not exported.", path);
 333                 errno = EACCES;
 334                 return -1;
 335         }
 336
 337         if (service->overridable) {
 338                 service_looking_at = service;
 339                 service_enabled = -1;
 340                 git_config(git_daemon_config, NULL);
 341                 if (0 <= service_enabled)
 342                         enabled = service_enabled;
 343         }
 344         if (!enabled) {
 345                 logerror("'%s': service not enabled for '%s'",
 346                          service->name, path);
 347                 errno = EACCES;
 348                 return -1;
 349         }
 350
 351         /*
 352          * We'll ignore SIGTERM from now on, we have a
 353          * good client.
 354          */
 355         signal(SIGTERM, SIG_IGN);
 356
 357         return service->fn();
 358 }
 359
 360 static int upload_pack(void)
 361 {
 362         /* Timeout as string */
 363         char timeout_buf[64];
 364
 365         snprintf(timeout_buf, sizeof timeout_buf, "--timeout=%u", timeout);
 366
 367         /* git-upload-pack only ever reads stuff, so this is safe */
 368         execl_git_cmd("upload-pack", "--strict", timeout_buf, ".", NULL);
 369         return -1;
 370 }
 371
 372 static int upload_archive(void)
 373 {
 374         execl_git_cmd("upload-archive", ".", NULL);
 375         return -1;
 376 }
 377
 378 static int receive_pack(void)
 379 {
 380         execl_git_cmd("receive-pack", ".", NULL);
 381         return -1;
 382 }
 383
 384 static struct daemon_service daemon_service[] = {
 385         { "upload-archive", "uploadarch", upload_archive, 0, 1 },
 386         { "upload-pack", "uploadpack", upload_pack, 1, 1 },
 387         { "receive-pack", "receivepack", receive_pack, 0, 1 },
 388 };
 389
 390 static void enable_service(const char *name, int ena)
 391 {
 392         int i;
 393         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 394                 if (!strcmp(daemon_service[i].name, name)) {
 395                         daemon_service[i].enabled = ena;
 396                         return;
 397                 }
 398         }
 399         die("No such service %s", name);
 400 }
 401
 402 static void make_service_overridable(const char *name, int ena)
 403 {
 404         int i;
 405         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 406                 if (!strcmp(daemon_service[i].name, name)) {
 407                         daemon_service[i].overridable = ena;
 408                         return;
 409                 }
 410         }
 411         die("No such service %s", name);
 412 }
 413
 414 /*
 415  * Separate the "extra args" information as supplied by the client connection.
 416  * Any resulting data is squirreled away in the given interpolation table.
 417  */
 418 static void parse_extra_args(struct interp *table, char *extra_args, int buflen)
 419 {
 420         char *val;
 421         int vallen;
 422         char *end = extra_args + buflen;
 423
 424         while (extra_args < end && *extra_args) {
 425                 saw_extended_args = 1;
 426                 if (strncasecmp("host=", extra_args, 5) == 0) {
 427                         val = extra_args + 5;
 428                         vallen = strlen(val) + 1;
 429                         if (*val) {
 430                                 /* Split <host>:<port> at colon. */
 431                                 char *host = val;
 432                                 char *port = strrchr(host, ':');
 433                                 if (port) {
 434                                         *port = 0;
 435                                         port++;
 436                                         interp_set_entry(table, INTERP_SLOT_PORT, port);
 437                                 }
 438                                 interp_set_entry(table, INTERP_SLOT_HOST, host);
 439                         }
 440
 441                         /* On to the next one */
 442                         extra_args = val + vallen;
 443                 }
 444         }
 445 }
 446
 447 static void fill_in_extra_table_entries(struct interp *itable)
 448 {
 449         char *hp;
 450
 451         /*
 452          * Replace literal host with lowercase-ized hostname.
 453          */
 454         hp = interp_table[INTERP_SLOT_HOST].value;
 455         if (!hp)
 456                 return;
 457         for ( ; *hp; hp++)
 458                 *hp = tolower(*hp);
 459
 460         /*
 461          * Locate canonical hostname and its IP address.
 462          */
 463 #ifndef NO_IPV6
 464         {
 465                 struct addrinfo hints;
 466                 struct addrinfo *ai, *ai0;
 467                 int gai;
 468                 static char addrbuf[HOST_NAME_MAX + 1];
 469
 470                 memset(&hints, 0, sizeof(hints));
 471                 hints.ai_flags = AI_CANONNAME;
 472
 473                 gai = getaddrinfo(interp_table[INTERP_SLOT_HOST].value, 0, &hints, &ai0);
 474                 if (!gai) {
 475                         for (ai = ai0; ai; ai = ai->ai_next) {
 476                                 struct sockaddr_in *sin_addr = (void *)ai->ai_addr;
 477
 478                                 inet_ntop(AF_INET, &sin_addr->sin_addr,
 479                                           addrbuf, sizeof(addrbuf));
 480                                 interp_set_entry(interp_table,
 481                                                  INTERP_SLOT_CANON_HOST, ai->ai_canonname);
 482                                 interp_set_entry(interp_table,
 483                                                  INTERP_SLOT_IP, addrbuf);
 484                                 break;
 485                         }
 486                         freeaddrinfo(ai0);
 487                 }
 488         }
 489 #else
 490         {
 491                 struct hostent *hent;
 492                 struct sockaddr_in sa;
 493                 char **ap;
 494                 static char addrbuf[HOST_NAME_MAX + 1];
 495
 496                 hent = gethostbyname(interp_table[INTERP_SLOT_HOST].value);
 497
 498                 ap = hent->h_addr_list;
 499                 memset(&sa, 0, sizeof sa);
 500                 sa.sin_family = hent->h_addrtype;
 501                 sa.sin_port = htons(0);
 502                 memcpy(&sa.sin_addr, *ap, hent->h_length);
 503
 504                 inet_ntop(hent->h_addrtype, &sa.sin_addr,
 505                           addrbuf, sizeof(addrbuf));
 506
 507                 interp_set_entry(interp_table, INTERP_SLOT_CANON_HOST, hent->h_name);
 508                 interp_set_entry(interp_table, INTERP_SLOT_IP, addrbuf);
 509         }
 510 #endif
 511 }
 512
 513
 514 static int execute(struct sockaddr *addr)
 515 {
 516         static char line[1000];
 517         int pktlen, len, i;
 518
 519         if (addr) {
 520                 char addrbuf[256] = "";
 521                 int port = -1;
 522
 523                 if (addr->sa_family == AF_INET) {
 524                         struct sockaddr_in *sin_addr = (void *) addr;
 525                         inet_ntop(addr->sa_family, &sin_addr->sin_addr, addrbuf, sizeof(addrbuf));
 526                         port = ntohs(sin_addr->sin_port);
 527 #ifndef NO_IPV6
 528                 } else if (addr && addr->sa_family == AF_INET6) {
 529                         struct sockaddr_in6 *sin6_addr = (void *) addr;
 530
 531                         char *buf = addrbuf;
 532                         *buf++ = '['; *buf = '\0'; /* stpcpy() is cool */
 533                         inet_ntop(AF_INET6, &sin6_addr->sin6_addr, buf, sizeof(addrbuf) - 1);
 534                         strcat(buf, "]");
 535
 536                         port = ntohs(sin6_addr->sin6_port);
 537 #endif
 538                 }
 539                 loginfo("Connection from %s:%d", addrbuf, port);
 540         }
 541
 542         alarm(init_timeout ? init_timeout : timeout);
 543         pktlen = packet_read_line(0, line, sizeof(line));
 544         alarm(0);
 545
 546         len = strlen(line);
 547         if (pktlen != len)
 548                 loginfo("Extended attributes (%d bytes) exist <%.*s>",
 549                         (int) pktlen - len,
 550                         (int) pktlen - len, line + len + 1);
 551         if (len && line[len-1] == '\n') {
 552                 line[--len] = 0;
 553                 pktlen--;
 554         }
 555
 556         /*
 557          * Initialize the path interpolation table for this connection.
 558          */
 559         interp_clear_table(interp_table, ARRAY_SIZE(interp_table));
 560         interp_set_entry(interp_table, INTERP_SLOT_PERCENT, "%");
 561
 562         if (len != pktlen) {
 563             parse_extra_args(interp_table, line + len + 1, pktlen - len - 1);
 564             fill_in_extra_table_entries(interp_table);
 565         }
 566
 567         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 568                 struct daemon_service *s = &(daemon_service[i]);
 569                 int namelen = strlen(s->name);
 570                 if (!prefixcmp(line, "git-") &&
 571                     !strncmp(s->name, line + 4, namelen) &&
 572                     line[namelen + 4] == ' ') {
 573                         /*
 574                          * Note: The directory here is probably context sensitive,
 575                          * and might depend on the actual service being performed.
 576                          */
 577                         interp_set_entry(interp_table,
 578                                          INTERP_SLOT_DIR, line + namelen + 5);
 579                         return run_service(interp_table, s);
 580                 }
 581         }
 582
 583         logerror("Protocol error: '%s'", line);
 584         return -1;
 585 }
 586
 587
 588 /*
 589  * We count spawned/reaped separately, just to avoid any
 590  * races when updating them from signals. The SIGCHLD handler
 591  * will only update children_reaped, and the fork logic will
 592  * only update children_spawned.
 593  *
 594  * MAX_CHILDREN should be a power-of-two to make the modulus
 595  * operation cheap. It should also be at least twice
 596  * the maximum number of connections we will ever allow.
 597  */
 598 #define MAX_CHILDREN 128
 599
 600 static int max_connections = 25;
 601
 602 /* These are updated by the signal handler */
 603 static volatile unsigned int children_reaped;
 604 static pid_t dead_child[MAX_CHILDREN];
 605
 606 /* These are updated by the main loop */
 607 static unsigned int children_spawned;
 608 static unsigned int children_deleted;
 609
 610 static struct child {
 611         pid_t pid;
 612         int addrlen;
 613         struct sockaddr_storage address;
 614 } live_child[MAX_CHILDREN];
 615
 616 static void add_child(int idx, pid_t pid, struct sockaddr *addr, int addrlen)
 617 {
 618         live_child[idx].pid = pid;
 619         live_child[idx].addrlen = addrlen;
 620         memcpy(&live_child[idx].address, addr, addrlen);
 621 }
 622
 623 /*
 624  * Walk from "deleted" to "spawned", and remove child "pid".
 625  *
 626  * We move everything up by one, since the new "deleted" will
 627  * be one higher.
 628  */
 629 static void remove_child(pid_t pid, unsigned deleted, unsigned spawned)
 630 {
 631         struct child n;
 632
 633         deleted %= MAX_CHILDREN;
 634         spawned %= MAX_CHILDREN;
 635         if (live_child[deleted].pid == pid) {
 636                 live_child[deleted].pid = -1;
 637                 return;
 638         }
 639         n = live_child[deleted];
 640         for (;;) {
 641                 struct child m;
 642                 deleted = (deleted + 1) % MAX_CHILDREN;
 643                 if (deleted == spawned)
 644                         die("could not find dead child %d\n", pid);
 645                 m = live_child[deleted];
 646                 live_child[deleted] = n;
 647                 if (m.pid == pid)
 648                         return;
 649                 n = m;
 650         }
 651 }
 652
 653 /*
 654  * This gets called if the number of connections grows
 655  * past "max_connections".
 656  *
 657  * We _should_ start off by searching for connections
 658  * from the same IP, and if there is some address wth
 659  * multiple connections, we should kill that first.
 660  *
 661  * As it is, we just "randomly" kill 25% of the connections,
 662  * and our pseudo-random generator sucks too. I have no
 663  * shame.
 664  *
 665  * Really, this is just a place-holder for a _real_ algorithm.
 666  */
 667 static void kill_some_children(int signo, unsigned start, unsigned stop)
 668 {
 669         start %= MAX_CHILDREN;
 670         stop %= MAX_CHILDREN;
 671         while (start != stop) {
 672                 if (!(start & 3))
 673                         kill(live_child[start].pid, signo);
 674                 start = (start + 1) % MAX_CHILDREN;
 675         }
 676 }
 677
 678 static void check_dead_children(void)
 679 {
 680         unsigned spawned, reaped, deleted;
 681
 682         for (;;) {
 683                 int status;
 684                 pid_t pid = waitpid(-1, &status, WNOHANG);
 685
 686                 if (pid > 0) {
 687                         unsigned reaped = children_reaped;
 688                         if (!WIFEXITED(status) || WEXITSTATUS(status) > 0)
 689                                 pid = -pid;
 690                         dead_child[reaped % MAX_CHILDREN] = pid;
 691                         children_reaped = reaped + 1;
 692                         continue;
 693                 }
 694                 break;
 695         }
 696
 697         spawned = children_spawned;
 698         reaped = children_reaped;
 699         deleted = children_deleted;
 700
 701         while (deleted < reaped) {
 702                 pid_t pid = dead_child[deleted % MAX_CHILDREN];
 703                 const char *dead = pid < 0 ? " (with error)" : "";
 704
 705                 if (pid < 0)
 706                         pid = -pid;
 707
 708                 /* XXX: Custom logging, since we don't wanna getpid() */
 709                 if (verbose) {
 710                         if (log_syslog)
 711                                 syslog(LOG_INFO, "[%d] Disconnected%s",
 712                                                 pid, dead);
 713                         else
 714                                 fprintf(stderr, "[%d] Disconnected%s\n",
 715                                                 pid, dead);
 716                 }
 717                 remove_child(pid, deleted, spawned);
 718                 deleted++;
 719         }
 720         children_deleted = deleted;
 721 }
 722
 723 static void check_max_connections(void)
 724 {
 725         for (;;) {
 726                 int active;
 727                 unsigned spawned, deleted;
 728
 729                 check_dead_children();
 730
 731                 spawned = children_spawned;
 732                 deleted = children_deleted;
 733
 734                 active = spawned - deleted;
 735                 if (active <= max_connections)
 736                         break;
 737
 738                 /* Kill some unstarted connections with SIGTERM */
 739                 kill_some_children(SIGTERM, deleted, spawned);
 740                 if (active <= max_connections << 1)
 741                         break;
 742
 743                 /* If the SIGTERM thing isn't helping use SIGKILL */
 744                 kill_some_children(SIGKILL, deleted, spawned);
 745                 sleep(1);
 746         }
 747 }
 748
 749 static void handle(int incoming, struct sockaddr *addr, int addrlen)
 750 {
 751         pid_t pid = fork();
 752
 753         if (pid) {
 754                 unsigned idx;
 755
 756                 close(incoming);
 757                 if (pid < 0)
 758                         return;
 759
 760                 idx = children_spawned % MAX_CHILDREN;
 761                 children_spawned++;
 762                 add_child(idx, pid, addr, addrlen);
 763
 764                 check_max_connections();
 765                 return;
 766         }
 767
 768         dup2(incoming, 0);
 769         dup2(incoming, 1);
 770         close(incoming);
 771
 772         exit(execute(addr));
 773 }
 774
 775 static void child_handler(int signo)
 776 {
 777         /* Otherwise empty handler because systemcalls will get interrupted
 778          * upon signal receipt
 779          * SysV needs the handler to be rearmed
 780          */
 781         signal(SIGCHLD, child_handler);
 782 }
 783
 784 static int set_reuse_addr(int sockfd)
 785 {
 786         int on = 1;
 787
 788         if (!reuseaddr)
 789                 return 0;
 790         return setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
 791                           &on, sizeof(on));
 792 }
 793
 794 #ifndef NO_IPV6
 795
 796 static int socksetup(char *listen_addr, int listen_port, int **socklist_p)
 797 {
 798         int socknum = 0, *socklist = NULL;
 799         int maxfd = -1;
 800         char pbuf[NI_MAXSERV];
 801         struct addrinfo hints, *ai0, *ai;
 802         int gai;
 803         long flags;
 804
 805         sprintf(pbuf, "%d", listen_port);
 806         memset(&hints, 0, sizeof(hints));
 807         hints.ai_family = AF_UNSPEC;
 808         hints.ai_socktype = SOCK_STREAM;
 809         hints.ai_protocol = IPPROTO_TCP;
 810         hints.ai_flags = AI_PASSIVE;
 811
 812         gai = getaddrinfo(listen_addr, pbuf, &hints, &ai0);
 813         if (gai)
 814                 die("getaddrinfo() failed: %s\n", gai_strerror(gai));
 815
 816         for (ai = ai0; ai; ai = ai->ai_next) {
 817                 int sockfd;
 818
 819                 sockfd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
 820                 if (sockfd < 0)
 821                         continue;
 822                 if (sockfd >= FD_SETSIZE) {
 823                         logerror("Socket descriptor too large");
 824                         close(sockfd);
 825                         continue;
 826                 }
 827
 828 #ifdef IPV6_V6ONLY
 829                 if (ai->ai_family == AF_INET6) {
 830                         int on = 1;
 831                         setsockopt(sockfd, IPPROTO_IPV6, IPV6_V6ONLY,
 832                                    &on, sizeof(on));
 833                         /* Note: error is not fatal */
 834                 }
 835 #endif
 836
 837                 if (set_reuse_addr(sockfd)) {
 838                         close(sockfd);
 839                         continue;
 840                 }
 841
 842                 if (bind(sockfd, ai->ai_addr, ai->ai_addrlen) < 0) {
 843                         close(sockfd);
 844                         continue;       /* not fatal */
 845                 }
 846                 if (listen(sockfd, 5) < 0) {
 847                         close(sockfd);
 848                         continue;       /* not fatal */
 849                 }
 850
 851                 flags = fcntl(sockfd, F_GETFD, 0);
 852                 if (flags >= 0)
 853                         fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
 854
 855                 socklist = xrealloc(socklist, sizeof(int) * (socknum + 1));
 856                 socklist[socknum++] = sockfd;
 857
 858                 if (maxfd < sockfd)
 859                         maxfd = sockfd;
 860         }
 861
 862         freeaddrinfo(ai0);
 863
 864         *socklist_p = socklist;
 865         return socknum;
 866 }
 867
 868 #else /* NO_IPV6 */
 869
 870 static int socksetup(char *listen_addr, int listen_port, int **socklist_p)
 871 {
 872         struct sockaddr_in sin;
 873         int sockfd;
 874         long flags;
 875
 876         memset(&sin, 0, sizeof sin);
 877         sin.sin_family = AF_INET;
 878         sin.sin_port = htons(listen_port);
 879
 880         if (listen_addr) {
 881                 /* Well, host better be an IP address here. */
 882                 if (inet_pton(AF_INET, listen_addr, &sin.sin_addr.s_addr) <= 0)
 883                         return 0;
 884         } else {
 885                 sin.sin_addr.s_addr = htonl(INADDR_ANY);
 886         }
 887
 888         sockfd = socket(AF_INET, SOCK_STREAM, 0);
 889         if (sockfd < 0)
 890                 return 0;
 891
 892         if (set_reuse_addr(sockfd)) {
 893                 close(sockfd);
 894                 return 0;
 895         }
 896
 897         if ( bind(sockfd, (struct sockaddr *)&sin, sizeof sin) < 0 ) {
 898                 close(sockfd);
 899                 return 0;
 900         }
 901
 902         if (listen(sockfd, 5) < 0) {
 903                 close(sockfd);
 904                 return 0;
 905         }
 906
 907         flags = fcntl(sockfd, F_GETFD, 0);
 908         if (flags >= 0)
 909                 fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
 910
 911         *socklist_p = xmalloc(sizeof(int));
 912         **socklist_p = sockfd;
 913         return 1;
 914 }
 915
 916 #endif
 917
 918 static int service_loop(int socknum, int *socklist)
 919 {
 920         struct pollfd *pfd;
 921         int i;
 922
 923         pfd = xcalloc(socknum, sizeof(struct pollfd));
 924
 925         for (i = 0; i < socknum; i++) {
 926                 pfd[i].fd = socklist[i];
 927                 pfd[i].events = POLLIN;
 928         }
 929
 930         signal(SIGCHLD, child_handler);
 931
 932         for (;;) {
 933                 int i;
 934
 935                 check_dead_children();
 936
 937                 if (poll(pfd, socknum, -1) < 0) {
 938                         if (errno != EINTR) {
 939                                 logerror("Poll failed, resuming: %s",
 940                                       strerror(errno));
 941                                 sleep(1);
 942                         }
 943                         continue;
 944                 }
 945
 946                 for (i = 0; i < socknum; i++) {
 947                         if (pfd[i].revents & POLLIN) {
 948                                 struct sockaddr_storage ss;
 949                                 unsigned int sslen = sizeof(ss);
 950                                 int incoming = accept(pfd[i].fd, (struct sockaddr *)&ss, &sslen);
 951                                 if (incoming < 0) {
 952                                         switch (errno) {
 953                                         case EAGAIN:
 954                                         case EINTR:
 955                                         case ECONNABORTED:
 956                                                 continue;
 957                                         default:
 958                                                 die("accept returned %s", strerror(errno));
 959                                         }
 960                                 }
 961                                 handle(incoming, (struct sockaddr *)&ss, sslen);
 962                         }
 963                 }
 964         }
 965 }
 966
 967 /* if any standard file descriptor is missing open it to /dev/null */
 968 static void sanitize_stdfds(void)
 969 {
 970         int fd = open("/dev/null", O_RDWR, 0);
 971         while (fd != -1 && fd < 2)
 972                 fd = dup(fd);
 973         if (fd == -1)
 974                 die("open /dev/null or dup failed: %s", strerror(errno));
 975         if (fd > 2)
 976                 close(fd);
 977 }
 978
 979 static void daemonize(void)
 980 {
 981         switch (fork()) {
 982                 case 0:
 983                         break;
 984                 case -1:
 985                         die("fork failed: %s", strerror(errno));
 986                 default:
 987                         exit(0);
 988         }
 989         if (setsid() == -1)
 990                 die("setsid failed: %s", strerror(errno));
 991         close(0);
 992         close(1);
 993         close(2);
 994         sanitize_stdfds();
 995 }
 996
 997 static void store_pid(const char *path)
 998 {
 999         FILE *f = fopen(path, "w");
1000         if (!f)
1001                 die("cannot open pid file %s: %s", path, strerror(errno));
1002         if (fprintf(f, "%d\n", getpid()) < 0 || fclose(f) != 0)
1003                 die("failed to write pid file %s: %s", path, strerror(errno));
1004 }
1005
1006 static int serve(char *listen_addr, int listen_port, struct passwd *pass, gid_t gid)
1007 {
1008         int socknum, *socklist;
1009
1010         socknum = socksetup(listen_addr, listen_port, &socklist);
1011         if (socknum == 0)
1012                 die("unable to allocate any listen sockets on host %s port %u",
1013                     listen_addr, listen_port);
1014
1015         if (pass && gid &&
1016             (initgroups(pass->pw_name, gid) || setgid (gid) ||
1017              setuid(pass->pw_uid)))
1018                 die("cannot drop privileges");
1019
1020         return service_loop(socknum, socklist);
1021 }
1022
1023 int main(int argc, char **argv)
1024 {
1025         int listen_port = 0;
1026         char *listen_addr = NULL;
1027         int inetd_mode = 0;
1028         const char *pid_file = NULL, *user_name = NULL, *group_name = NULL;
1029         int detach = 0;
1030         struct passwd *pass = NULL;
1031         struct group *group;
1032         gid_t gid = 0;
1033         int i;
1034
1035         for (i = 1; i < argc; i++) {
1036                 char *arg = argv[i];
1037
1038                 if (!prefixcmp(arg, "--listen=")) {
1039                     char *p = arg + 9;
1040                     char *ph = listen_addr = xmalloc(strlen(arg + 9) + 1);
1041                     while (*p)
1042                         *ph++ = tolower(*p++);
1043                     *ph = 0;
1044                     continue;
1045                 }
1046                 if (!prefixcmp(arg, "--port=")) {
1047                         char *end;
1048                         unsigned long n;
1049                         n = strtoul(arg+7, &end, 0);
1050                         if (arg[7] && !*end) {
1051                                 listen_port = n;
1052                                 continue;
1053                         }
1054                 }
1055                 if (!strcmp(arg, "--inetd")) {
1056                         inetd_mode = 1;
1057                         log_syslog = 1;
1058                         continue;
1059                 }
1060                 if (!strcmp(arg, "--verbose")) {
1061                         verbose = 1;
1062                         continue;
1063                 }
1064                 if (!strcmp(arg, "--syslog")) {
1065                         log_syslog = 1;
1066                         continue;
1067                 }
1068                 if (!strcmp(arg, "--export-all")) {
1069                         export_all_trees = 1;
1070                         continue;
1071                 }
1072                 if (!prefixcmp(arg, "--timeout=")) {
1073                         timeout = atoi(arg+10);
1074                         continue;
1075                 }
1076                 if (!prefixcmp(arg, "--init-timeout=")) {
1077                         init_timeout = atoi(arg+15);
1078                         continue;
1079                 }
1080                 if (!strcmp(arg, "--strict-paths")) {
1081                         strict_paths = 1;
1082                         continue;
1083                 }
1084                 if (!prefixcmp(arg, "--base-path=")) {
1085                         base_path = arg+12;
1086                         continue;
1087                 }
1088                 if (!strcmp(arg, "--base-path-relaxed")) {
1089                         base_path_relaxed = 1;
1090                         continue;
1091                 }
1092                 if (!prefixcmp(arg, "--interpolated-path=")) {
1093                         interpolated_path = arg+20;
1094                         continue;
1095                 }
1096                 if (!strcmp(arg, "--reuseaddr")) {
1097                         reuseaddr = 1;
1098                         continue;
1099                 }
1100                 if (!strcmp(arg, "--user-path")) {
1101                         user_path = "";
1102                         continue;
1103                 }
1104                 if (!prefixcmp(arg, "--user-path=")) {
1105                         user_path = arg + 12;
1106                         continue;
1107                 }
1108                 if (!prefixcmp(arg, "--pid-file=")) {
1109                         pid_file = arg + 11;
1110                         continue;
1111                 }
1112                 if (!strcmp(arg, "--detach")) {
1113                         detach = 1;
1114                         log_syslog = 1;
1115                         continue;
1116                 }
1117                 if (!prefixcmp(arg, "--user=")) {
1118                         user_name = arg + 7;
1119                         continue;
1120                 }
1121                 if (!prefixcmp(arg, "--group=")) {
1122                         group_name = arg + 8;
1123                         continue;
1124                 }
1125                 if (!prefixcmp(arg, "--enable=")) {
1126                         enable_service(arg + 9, 1);
1127                         continue;
1128                 }
1129                 if (!prefixcmp(arg, "--disable=")) {
1130                         enable_service(arg + 10, 0);
1131                         continue;
1132                 }
1133                 if (!prefixcmp(arg, "--allow-override=")) {
1134                         make_service_overridable(arg + 17, 1);
1135                         continue;
1136                 }
1137                 if (!prefixcmp(arg, "--forbid-override=")) {
1138                         make_service_overridable(arg + 18, 0);
1139                         continue;
1140                 }
1141                 if (!strcmp(arg, "--")) {
1142                         ok_paths = &argv[i+1];
1143                         break;
1144                 } else if (arg[0] != '-') {
1145                         ok_paths = &argv[i];
1146                         break;
1147                 }
1148
1149                 usage(daemon_usage);
1150         }
1151
1152         if (log_syslog) {
1153                 openlog("git-daemon", LOG_PID, LOG_DAEMON);
1154                 set_die_routine(daemon_die);
1155         }
1156         else
1157                 setlinebuf(stderr); /* avoid splitting a message in the middle */
1158
1159         if (inetd_mode && (group_name || user_name))
1160                 die("--user and --group are incompatible with --inetd");
1161
1162         if (inetd_mode && (listen_port || listen_addr))
1163                 die("--listen= and --port= are incompatible with --inetd");
1164         else if (listen_port == 0)
1165                 listen_port = DEFAULT_GIT_PORT;
1166
1167         if (group_name && !user_name)
1168                 die("--group supplied without --user");
1169
1170         if (user_name) {
1171                 pass = getpwnam(user_name);
1172                 if (!pass)
1173                         die("user not found - %s", user_name);
1174
1175                 if (!group_name)
1176                         gid = pass->pw_gid;
1177                 else {
1178                         group = getgrnam(group_name);
1179                         if (!group)
1180                                 die("group not found - %s", group_name);
1181
1182                         gid = group->gr_gid;
1183                 }
1184         }
1185
1186         if (strict_paths && (!ok_paths || !*ok_paths))
1187                 die("option --strict-paths requires a whitelist");
1188
1189         if (base_path) {
1190                 struct stat st;
1191
1192                 if (stat(base_path, &st) || !S_ISDIR(st.st_mode))
1193                         die("base-path '%s' does not exist or "
1194                             "is not a directory", base_path);
1195         }
1196
1197         if (inetd_mode) {
1198                 struct sockaddr_storage ss;
1199                 struct sockaddr *peer = (struct sockaddr *)&ss;
1200                 socklen_t slen = sizeof(ss);
1201
1202                 freopen("/dev/null", "w", stderr);
1203
1204                 if (getpeername(0, peer, &slen))
1205                         peer = NULL;
1206
1207                 return execute(peer);
1208         }
1209
1210         if (detach) {
1211                 daemonize();
1212                 loginfo("Ready to rumble");
1213         }
1214         else
1215                 sanitize_stdfds();
1216
1217         if (pid_file)
1218                 store_pid(pid_file);
1219
1220         return serve(listen_addr, listen_port, pass, gid);
1221 }