daemon.c

   1 #include <signal.h>
   2 #include <sys/wait.h>
   3 #include <sys/socket.h>
   4 #include <sys/time.h>
   5 #include <sys/poll.h>
   6 #include <netdb.h>
   7 #include <netinet/in.h>
   8 #include <arpa/inet.h>
   9 #include <syslog.h>
  10 #include <pwd.h>
  11 #include <grp.h>
  12 #include "pkt-line.h"
  13 #include "cache.h"
  14 #include "exec_cmd.h"
  15 #include "interpolate.h"
  16
  17 static int log_syslog;
  18 static int verbose;
  19 static int reuseaddr;
  20
  21 static const char daemon_usage[] =
  22 "git-daemon [--verbose] [--syslog] [--inetd | --port=n] [--export-all]\n"
  23 "           [--timeout=n] [--init-timeout=n] [--strict-paths]\n"
  24 "           [--base-path=path] [--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 "           [--user=user [[--group=group]] [directory...]";
  29
  30 /* List of acceptable pathname prefixes */
  31 static char **ok_paths;
  32 static int strict_paths;
  33
  34 /* If this is set, git-daemon-export-ok is not required */
  35 static int export_all_trees;
  36
  37 /* Take all paths relative to this one if non-NULL */
  38 static char *base_path;
  39 static char *interpolated_path;
  40
  41 /* Flag indicating client sent extra args. */
  42 static int saw_extended_args;
  43
  44 /* If defined, ~user notation is allowed and the string is inserted
  45  * after ~user/.  E.g. a request to git://host/~alice/frotz would
  46  * go to /home/alice/pub_git/frotz with --user-path=pub_git.
  47  */
  48 static const char *user_path;
  49
  50 /* Timeout, and initial timeout */
  51 static unsigned int timeout;
  52 static unsigned int init_timeout;
  53
  54 /*
  55  * Static table for now.  Ugh.
  56  * Feel free to make dynamic as needed.
  57  */
  58 #define INTERP_SLOT_HOST        (0)
  59 #define INTERP_SLOT_DIR         (1)
  60 #define INTERP_SLOT_PERCENT     (2)
  61
  62 static struct interp interp_table[] = {
  63         { "%H", 0},
  64         { "%D", 0},
  65         { "%%", "%"},
  66 };
  67
  68
  69 static void logreport(int priority, const char *err, va_list params)
  70 {
  71         /* We should do a single write so that it is atomic and output
  72          * of several processes do not get intermingled. */
  73         char buf[1024];
  74         int buflen;
  75         int maxlen, msglen;
  76
  77         /* sizeof(buf) should be big enough for "[pid] \n" */
  78         buflen = snprintf(buf, sizeof(buf), "[%ld] ", (long) getpid());
  79
  80         maxlen = sizeof(buf) - buflen - 1; /* -1 for our own LF */
  81         msglen = vsnprintf(buf + buflen, maxlen, err, params);
  82
  83         if (log_syslog) {
  84                 syslog(priority, "%s", buf);
  85                 return;
  86         }
  87
  88         /* maxlen counted our own LF but also counts space given to
  89          * vsnprintf for the terminating NUL.  We want to make sure that
  90          * we have space for our own LF and NUL after the "meat" of the
  91          * message, so truncate it at maxlen - 1.
  92          */
  93         if (msglen > maxlen - 1)
  94                 msglen = maxlen - 1;
  95         else if (msglen < 0)
  96                 msglen = 0; /* Protect against weird return values. */
  97         buflen += msglen;
  98
  99         buf[buflen++] = '\n';
 100         buf[buflen] = '\0';
 101
 102         write(2, buf, buflen);
 103 }
 104
 105 static void logerror(const char *err, ...)
 106 {
 107         va_list params;
 108         va_start(params, err);
 109         logreport(LOG_ERR, err, params);
 110         va_end(params);
 111 }
 112
 113 static void loginfo(const char *err, ...)
 114 {
 115         va_list params;
 116         if (!verbose)
 117                 return;
 118         va_start(params, err);
 119         logreport(LOG_INFO, err, params);
 120         va_end(params);
 121 }
 122
 123 static void NORETURN daemon_die(const char *err, va_list params)
 124 {
 125         logreport(LOG_ERR, err, params);
 126         exit(1);
 127 }
 128
 129 static int avoid_alias(char *p)
 130 {
 131         int sl, ndot;
 132
 133         /*
 134          * This resurrects the belts and suspenders paranoia check by HPA
 135          * done in <435560F7.4080006@zytor.com> thread, now enter_repo()
 136          * does not do getcwd() based path canonicalizations.
 137          *
 138          * sl becomes true immediately after seeing '/' and continues to
 139          * be true as long as dots continue after that without intervening
 140          * non-dot character.
 141          */
 142         if (!p || (*p != '/' && *p != '~'))
 143                 return -1;
 144         sl = 1; ndot = 0;
 145         p++;
 146
 147         while (1) {
 148                 char ch = *p++;
 149                 if (sl) {
 150                         if (ch == '.')
 151                                 ndot++;
 152                         else if (ch == '/') {
 153                                 if (ndot < 3)
 154                                         /* reject //, /./ and /../ */
 155                                         return -1;
 156                                 ndot = 0;
 157                         }
 158                         else if (ch == 0) {
 159                                 if (0 < ndot && ndot < 3)
 160                                         /* reject /.$ and /..$ */
 161                                         return -1;
 162                                 return 0;
 163                         }
 164                         else
 165                                 sl = ndot = 0;
 166                 }
 167                 else if (ch == 0)
 168                         return 0;
 169                 else if (ch == '/') {
 170                         sl = 1;
 171                         ndot = 0;
 172                 }
 173         }
 174 }
 175
 176 static char *path_ok(struct interp *itable)
 177 {
 178         static char rpath[PATH_MAX];
 179         static char interp_path[PATH_MAX];
 180         char *path;
 181         char *dir;
 182
 183         dir = itable[INTERP_SLOT_DIR].value;
 184
 185         if (avoid_alias(dir)) {
 186                 logerror("'%s': aliased", dir);
 187                 return NULL;
 188         }
 189
 190         if (*dir == '~') {
 191                 if (!user_path) {
 192                         logerror("'%s': User-path not allowed", dir);
 193                         return NULL;
 194                 }
 195                 if (*user_path) {
 196                         /* Got either "~alice" or "~alice/foo";
 197                          * rewrite them to "~alice/%s" or
 198                          * "~alice/%s/foo".
 199                          */
 200                         int namlen, restlen = strlen(dir);
 201                         char *slash = strchr(dir, '/');
 202                         if (!slash)
 203                                 slash = dir + restlen;
 204                         namlen = slash - dir;
 205                         restlen -= namlen;
 206                         loginfo("userpath <%s>, request <%s>, namlen %d, restlen %d, slash <%s>", user_path, dir, namlen, restlen, slash);
 207                         snprintf(rpath, PATH_MAX, "%.*s/%s%.*s",
 208                                  namlen, dir, user_path, restlen, slash);
 209                         dir = rpath;
 210                 }
 211         }
 212         else if (interpolated_path && saw_extended_args) {
 213                 if (*dir != '/') {
 214                         /* Allow only absolute */
 215                         logerror("'%s': Non-absolute path denied (interpolated-path active)", dir);
 216                         return NULL;
 217                 }
 218
 219                 interpolate(interp_path, PATH_MAX, interpolated_path,
 220                             interp_table, ARRAY_SIZE(interp_table));
 221                 loginfo("Interpolated dir '%s'", interp_path);
 222
 223                 dir = interp_path;
 224         }
 225         else if (base_path) {
 226                 if (*dir != '/') {
 227                         /* Allow only absolute */
 228                         logerror("'%s': Non-absolute path denied (base-path active)", dir);
 229                         return NULL;
 230                 }
 231                 snprintf(rpath, PATH_MAX, "%s%s", base_path, dir);
 232                 dir = rpath;
 233         }
 234
 235         path = enter_repo(dir, strict_paths);
 236
 237         if (!path) {
 238                 logerror("'%s': unable to chdir or not a git archive", dir);
 239                 return NULL;
 240         }
 241
 242         if ( ok_paths && *ok_paths ) {
 243                 char **pp;
 244                 int pathlen = strlen(path);
 245
 246                 /* The validation is done on the paths after enter_repo
 247                  * appends optional {.git,.git/.git} and friends, but
 248                  * it does not use getcwd().  So if your /pub is
 249                  * a symlink to /mnt/pub, you can whitelist /pub and
 250                  * do not have to say /mnt/pub.
 251                  * Do not say /pub/.
 252                  */
 253                 for ( pp = ok_paths ; *pp ; pp++ ) {
 254                         int len = strlen(*pp);
 255                         if (len <= pathlen &&
 256                             !memcmp(*pp, path, len) &&
 257                             (path[len] == '\0' ||
 258                              (!strict_paths && path[len] == '/')))
 259                                 return path;
 260                 }
 261         }
 262         else {
 263                 /* be backwards compatible */
 264                 if (!strict_paths)
 265                         return path;
 266         }
 267
 268         logerror("'%s': not in whitelist", path);
 269         return NULL;            /* Fallthrough. Deny by default */
 270 }
 271
 272 typedef int (*daemon_service_fn)(void);
 273 struct daemon_service {
 274         const char *name;
 275         const char *config_name;
 276         daemon_service_fn fn;
 277         int enabled;
 278         int overridable;
 279 };
 280
 281 static struct daemon_service *service_looking_at;
 282 static int service_enabled;
 283
 284 static int git_daemon_config(const char *var, const char *value)
 285 {
 286         if (!strncmp(var, "daemon.", 7) &&
 287             !strcmp(var + 7, service_looking_at->config_name)) {
 288                 service_enabled = git_config_bool(var, value);
 289                 return 0;
 290         }
 291
 292         /* we are not interested in parsing any other configuration here */
 293         return 0;
 294 }
 295
 296 static int run_service(struct interp *itable, struct daemon_service *service)
 297 {
 298         const char *path;
 299         int enabled = service->enabled;
 300
 301         loginfo("Request %s for '%s'",
 302                 service->name,
 303                 itable[INTERP_SLOT_DIR].value);
 304
 305         if (!enabled && !service->overridable) {
 306                 logerror("'%s': service not enabled.", service->name);
 307                 errno = EACCES;
 308                 return -1;
 309         }
 310
 311         if (!(path = path_ok(itable)))
 312                 return -1;
 313
 314         /*
 315          * Security on the cheap.
 316          *
 317          * We want a readable HEAD, usable "objects" directory, and
 318          * a "git-daemon-export-ok" flag that says that the other side
 319          * is ok with us doing this.
 320          *
 321          * path_ok() uses enter_repo() and does whitelist checking.
 322          * We only need to make sure the repository is exported.
 323          */
 324
 325         if (!export_all_trees && access("git-daemon-export-ok", F_OK)) {
 326                 logerror("'%s': repository not exported.", path);
 327                 errno = EACCES;
 328                 return -1;
 329         }
 330
 331         if (service->overridable) {
 332                 service_looking_at = service;
 333                 service_enabled = -1;
 334                 git_config(git_daemon_config);
 335                 if (0 <= service_enabled)
 336                         enabled = service_enabled;
 337         }
 338         if (!enabled) {
 339                 logerror("'%s': service not enabled for '%s'",
 340                          service->name, path);
 341                 errno = EACCES;
 342                 return -1;
 343         }
 344
 345         /*
 346          * We'll ignore SIGTERM from now on, we have a
 347          * good client.
 348          */
 349         signal(SIGTERM, SIG_IGN);
 350
 351         return service->fn();
 352 }
 353
 354 static int upload_pack(void)
 355 {
 356         /* Timeout as string */
 357         char timeout_buf[64];
 358
 359         snprintf(timeout_buf, sizeof timeout_buf, "--timeout=%u", timeout);
 360
 361         /* git-upload-pack only ever reads stuff, so this is safe */
 362         execl_git_cmd("upload-pack", "--strict", timeout_buf, ".", NULL);
 363         return -1;
 364 }
 365
 366 static int upload_archive(void)
 367 {
 368         execl_git_cmd("upload-archive", ".", NULL);
 369         return -1;
 370 }
 371
 372 static struct daemon_service daemon_service[] = {
 373         { "upload-archive", "uploadarch", upload_archive, 0, 1 },
 374         { "upload-pack", "uploadpack", upload_pack, 1, 1 },
 375 };
 376
 377 static void enable_service(const char *name, int ena) {
 378         int i;
 379         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 380                 if (!strcmp(daemon_service[i].name, name)) {
 381                         daemon_service[i].enabled = ena;
 382                         return;
 383                 }
 384         }
 385         die("No such service %s", name);
 386 }
 387
 388 static void make_service_overridable(const char *name, int ena) {
 389         int i;
 390         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 391                 if (!strcmp(daemon_service[i].name, name)) {
 392                         daemon_service[i].overridable = ena;
 393                         return;
 394                 }
 395         }
 396         die("No such service %s", name);
 397 }
 398
 399 static void parse_extra_args(char *extra_args, int buflen)
 400 {
 401         char *val;
 402         int vallen;
 403         char *end = extra_args + buflen;
 404
 405         while (extra_args < end && *extra_args) {
 406                 saw_extended_args = 1;
 407                 if (strncasecmp("host=", extra_args, 5) == 0) {
 408                         val = extra_args + 5;
 409                         vallen = strlen(val) + 1;
 410                         if (*val) {
 411                                 char *save = xmalloc(vallen);
 412                                 interp_table[INTERP_SLOT_HOST].value = save;
 413                                 strlcpy(save, val, vallen);
 414                         }
 415                         /* On to the next one */
 416                         extra_args = val + vallen;
 417                 }
 418         }
 419 }
 420
 421 static int execute(struct sockaddr *addr)
 422 {
 423         static char line[1000];
 424         int pktlen, len, i;
 425
 426         if (addr) {
 427                 char addrbuf[256] = "";
 428                 int port = -1;
 429
 430                 if (addr->sa_family == AF_INET) {
 431                         struct sockaddr_in *sin_addr = (void *) addr;
 432                         inet_ntop(addr->sa_family, &sin_addr->sin_addr, addrbuf, sizeof(addrbuf));
 433                         port = sin_addr->sin_port;
 434 #ifndef NO_IPV6
 435                 } else if (addr && addr->sa_family == AF_INET6) {
 436                         struct sockaddr_in6 *sin6_addr = (void *) addr;
 437
 438                         char *buf = addrbuf;
 439                         *buf++ = '['; *buf = '\0'; /* stpcpy() is cool */
 440                         inet_ntop(AF_INET6, &sin6_addr->sin6_addr, buf, sizeof(addrbuf) - 1);
 441                         strcat(buf, "]");
 442
 443                         port = sin6_addr->sin6_port;
 444 #endif
 445                 }
 446                 loginfo("Connection from %s:%d", addrbuf, port);
 447         }
 448
 449         alarm(init_timeout ? init_timeout : timeout);
 450         pktlen = packet_read_line(0, line, sizeof(line));
 451         alarm(0);
 452
 453         len = strlen(line);
 454         if (pktlen != len)
 455                 loginfo("Extended attributes (%d bytes) exist <%.*s>",
 456                         (int) pktlen - len,
 457                         (int) pktlen - len, line + len + 1);
 458         if (len && line[len-1] == '\n')
 459                 line[--len] = 0;
 460
 461         if (len != pktlen)
 462             parse_extra_args(line + len + 1, pktlen - len - 1);
 463
 464         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 465                 struct daemon_service *s = &(daemon_service[i]);
 466                 int namelen = strlen(s->name);
 467                 if (!strncmp("git-", line, 4) &&
 468                     !strncmp(s->name, line + 4, namelen) &&
 469                     line[namelen + 4] == ' ') {
 470                         interp_table[INTERP_SLOT_DIR].value = line+namelen+5;
 471                         return run_service(interp_table, s);
 472                 }
 473         }
 474
 475         logerror("Protocol error: '%s'", line);
 476         return -1;
 477 }
 478
 479
 480 /*
 481  * We count spawned/reaped separately, just to avoid any
 482  * races when updating them from signals. The SIGCHLD handler
 483  * will only update children_reaped, and the fork logic will
 484  * only update children_spawned.
 485  *
 486  * MAX_CHILDREN should be a power-of-two to make the modulus
 487  * operation cheap. It should also be at least twice
 488  * the maximum number of connections we will ever allow.
 489  */
 490 #define MAX_CHILDREN 128
 491
 492 static int max_connections = 25;
 493
 494 /* These are updated by the signal handler */
 495 static volatile unsigned int children_reaped;
 496 static pid_t dead_child[MAX_CHILDREN];
 497
 498 /* These are updated by the main loop */
 499 static unsigned int children_spawned;
 500 static unsigned int children_deleted;
 501
 502 static struct child {
 503         pid_t pid;
 504         int addrlen;
 505         struct sockaddr_storage address;
 506 } live_child[MAX_CHILDREN];
 507
 508 static void add_child(int idx, pid_t pid, struct sockaddr *addr, int addrlen)
 509 {
 510         live_child[idx].pid = pid;
 511         live_child[idx].addrlen = addrlen;
 512         memcpy(&live_child[idx].address, addr, addrlen);
 513 }
 514
 515 /*
 516  * Walk from "deleted" to "spawned", and remove child "pid".
 517  *
 518  * We move everything up by one, since the new "deleted" will
 519  * be one higher.
 520  */
 521 static void remove_child(pid_t pid, unsigned deleted, unsigned spawned)
 522 {
 523         struct child n;
 524
 525         deleted %= MAX_CHILDREN;
 526         spawned %= MAX_CHILDREN;
 527         if (live_child[deleted].pid == pid) {
 528                 live_child[deleted].pid = -1;
 529                 return;
 530         }
 531         n = live_child[deleted];
 532         for (;;) {
 533                 struct child m;
 534                 deleted = (deleted + 1) % MAX_CHILDREN;
 535                 if (deleted == spawned)
 536                         die("could not find dead child %d\n", pid);
 537                 m = live_child[deleted];
 538                 live_child[deleted] = n;
 539                 if (m.pid == pid)
 540                         return;
 541                 n = m;
 542         }
 543 }
 544
 545 /*
 546  * This gets called if the number of connections grows
 547  * past "max_connections".
 548  *
 549  * We _should_ start off by searching for connections
 550  * from the same IP, and if there is some address wth
 551  * multiple connections, we should kill that first.
 552  *
 553  * As it is, we just "randomly" kill 25% of the connections,
 554  * and our pseudo-random generator sucks too. I have no
 555  * shame.
 556  *
 557  * Really, this is just a place-holder for a _real_ algorithm.
 558  */
 559 static void kill_some_children(int signo, unsigned start, unsigned stop)
 560 {
 561         start %= MAX_CHILDREN;
 562         stop %= MAX_CHILDREN;
 563         while (start != stop) {
 564                 if (!(start & 3))
 565                         kill(live_child[start].pid, signo);
 566                 start = (start + 1) % MAX_CHILDREN;
 567         }
 568 }
 569
 570 static void check_max_connections(void)
 571 {
 572         for (;;) {
 573                 int active;
 574                 unsigned spawned, reaped, deleted;
 575
 576                 spawned = children_spawned;
 577                 reaped = children_reaped;
 578                 deleted = children_deleted;
 579
 580                 while (deleted < reaped) {
 581                         pid_t pid = dead_child[deleted % MAX_CHILDREN];
 582                         remove_child(pid, deleted, spawned);
 583                         deleted++;
 584                 }
 585                 children_deleted = deleted;
 586
 587                 active = spawned - deleted;
 588                 if (active <= max_connections)
 589                         break;
 590
 591                 /* Kill some unstarted connections with SIGTERM */
 592                 kill_some_children(SIGTERM, deleted, spawned);
 593                 if (active <= max_connections << 1)
 594                         break;
 595
 596                 /* If the SIGTERM thing isn't helping use SIGKILL */
 597                 kill_some_children(SIGKILL, deleted, spawned);
 598                 sleep(1);
 599         }
 600 }
 601
 602 static void handle(int incoming, struct sockaddr *addr, int addrlen)
 603 {
 604         pid_t pid = fork();
 605
 606         if (pid) {
 607                 unsigned idx;
 608
 609                 close(incoming);
 610                 if (pid < 0)
 611                         return;
 612
 613                 idx = children_spawned % MAX_CHILDREN;
 614                 children_spawned++;
 615                 add_child(idx, pid, addr, addrlen);
 616
 617                 check_max_connections();
 618                 return;
 619         }
 620
 621         dup2(incoming, 0);
 622         dup2(incoming, 1);
 623         close(incoming);
 624
 625         exit(execute(addr));
 626 }
 627
 628 static void child_handler(int signo)
 629 {
 630         for (;;) {
 631                 int status;
 632                 pid_t pid = waitpid(-1, &status, WNOHANG);
 633
 634                 if (pid > 0) {
 635                         unsigned reaped = children_reaped;
 636                         dead_child[reaped % MAX_CHILDREN] = pid;
 637                         children_reaped = reaped + 1;
 638                         /* XXX: Custom logging, since we don't wanna getpid() */
 639                         if (verbose) {
 640                                 const char *dead = "";
 641                                 if (!WIFEXITED(status) || WEXITSTATUS(status) > 0)
 642                                         dead = " (with error)";
 643                                 if (log_syslog)
 644                                         syslog(LOG_INFO, "[%d] Disconnected%s", pid, dead);
 645                                 else
 646                                         fprintf(stderr, "[%d] Disconnected%s\n", pid, dead);
 647                         }
 648                         continue;
 649                 }
 650                 break;
 651         }
 652 }
 653
 654 static int set_reuse_addr(int sockfd)
 655 {
 656         int on = 1;
 657
 658         if (!reuseaddr)
 659                 return 0;
 660         return setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
 661                           &on, sizeof(on));
 662 }
 663
 664 #ifndef NO_IPV6
 665
 666 static int socksetup(int port, int **socklist_p)
 667 {
 668         int socknum = 0, *socklist = NULL;
 669         int maxfd = -1;
 670         char pbuf[NI_MAXSERV];
 671
 672         struct addrinfo hints, *ai0, *ai;
 673         int gai;
 674
 675         sprintf(pbuf, "%d", port);
 676         memset(&hints, 0, sizeof(hints));
 677         hints.ai_family = AF_UNSPEC;
 678         hints.ai_socktype = SOCK_STREAM;
 679         hints.ai_protocol = IPPROTO_TCP;
 680         hints.ai_flags = AI_PASSIVE;
 681
 682         gai = getaddrinfo(NULL, pbuf, &hints, &ai0);
 683         if (gai)
 684                 die("getaddrinfo() failed: %s\n", gai_strerror(gai));
 685
 686         for (ai = ai0; ai; ai = ai->ai_next) {
 687                 int sockfd;
 688
 689                 sockfd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
 690                 if (sockfd < 0)
 691                         continue;
 692                 if (sockfd >= FD_SETSIZE) {
 693                         error("too large socket descriptor.");
 694                         close(sockfd);
 695                         continue;
 696                 }
 697
 698 #ifdef IPV6_V6ONLY
 699                 if (ai->ai_family == AF_INET6) {
 700                         int on = 1;
 701                         setsockopt(sockfd, IPPROTO_IPV6, IPV6_V6ONLY,
 702                                    &on, sizeof(on));
 703                         /* Note: error is not fatal */
 704                 }
 705 #endif
 706
 707                 if (set_reuse_addr(sockfd)) {
 708                         close(sockfd);
 709                         continue;
 710                 }
 711
 712                 if (bind(sockfd, ai->ai_addr, ai->ai_addrlen) < 0) {
 713                         close(sockfd);
 714                         continue;       /* not fatal */
 715                 }
 716                 if (listen(sockfd, 5) < 0) {
 717                         close(sockfd);
 718                         continue;       /* not fatal */
 719                 }
 720
 721                 socklist = xrealloc(socklist, sizeof(int) * (socknum + 1));
 722                 socklist[socknum++] = sockfd;
 723
 724                 if (maxfd < sockfd)
 725                         maxfd = sockfd;
 726         }
 727
 728         freeaddrinfo(ai0);
 729
 730         *socklist_p = socklist;
 731         return socknum;
 732 }
 733
 734 #else /* NO_IPV6 */
 735
 736 static int socksetup(int port, int **socklist_p)
 737 {
 738         struct sockaddr_in sin;
 739         int sockfd;
 740
 741         sockfd = socket(AF_INET, SOCK_STREAM, 0);
 742         if (sockfd < 0)
 743                 return 0;
 744
 745         memset(&sin, 0, sizeof sin);
 746         sin.sin_family = AF_INET;
 747         sin.sin_addr.s_addr = htonl(INADDR_ANY);
 748         sin.sin_port = htons(port);
 749
 750         if (set_reuse_addr(sockfd)) {
 751                 close(sockfd);
 752                 return 0;
 753         }
 754
 755         if ( bind(sockfd, (struct sockaddr *)&sin, sizeof sin) < 0 ) {
 756                 close(sockfd);
 757                 return 0;
 758         }
 759
 760         if (listen(sockfd, 5) < 0) {
 761                 close(sockfd);
 762                 return 0;
 763         }
 764
 765         *socklist_p = xmalloc(sizeof(int));
 766         **socklist_p = sockfd;
 767         return 1;
 768 }
 769
 770 #endif
 771
 772 static int service_loop(int socknum, int *socklist)
 773 {
 774         struct pollfd *pfd;
 775         int i;
 776
 777         pfd = xcalloc(socknum, sizeof(struct pollfd));
 778
 779         for (i = 0; i < socknum; i++) {
 780                 pfd[i].fd = socklist[i];
 781                 pfd[i].events = POLLIN;
 782         }
 783
 784         signal(SIGCHLD, child_handler);
 785
 786         for (;;) {
 787                 int i;
 788
 789                 if (poll(pfd, socknum, -1) < 0) {
 790                         if (errno != EINTR) {
 791                                 error("poll failed, resuming: %s",
 792                                       strerror(errno));
 793                                 sleep(1);
 794                         }
 795                         continue;
 796                 }
 797
 798                 for (i = 0; i < socknum; i++) {
 799                         if (pfd[i].revents & POLLIN) {
 800                                 struct sockaddr_storage ss;
 801                                 unsigned int sslen = sizeof(ss);
 802                                 int incoming = accept(pfd[i].fd, (struct sockaddr *)&ss, &sslen);
 803                                 if (incoming < 0) {
 804                                         switch (errno) {
 805                                         case EAGAIN:
 806                                         case EINTR:
 807                                         case ECONNABORTED:
 808                                                 continue;
 809                                         default:
 810                                                 die("accept returned %s", strerror(errno));
 811                                         }
 812                                 }
 813                                 handle(incoming, (struct sockaddr *)&ss, sslen);
 814                         }
 815                 }
 816         }
 817 }
 818
 819 /* if any standard file descriptor is missing open it to /dev/null */
 820 static void sanitize_stdfds(void)
 821 {
 822         int fd = open("/dev/null", O_RDWR, 0);
 823         while (fd != -1 && fd < 2)
 824                 fd = dup(fd);
 825         if (fd == -1)
 826                 die("open /dev/null or dup failed: %s", strerror(errno));
 827         if (fd > 2)
 828                 close(fd);
 829 }
 830
 831 static void daemonize(void)
 832 {
 833         switch (fork()) {
 834                 case 0:
 835                         break;
 836                 case -1:
 837                         die("fork failed: %s", strerror(errno));
 838                 default:
 839                         exit(0);
 840         }
 841         if (setsid() == -1)
 842                 die("setsid failed: %s", strerror(errno));
 843         close(0);
 844         close(1);
 845         close(2);
 846         sanitize_stdfds();
 847 }
 848
 849 static void store_pid(const char *path)
 850 {
 851         FILE *f = fopen(path, "w");
 852         if (!f)
 853                 die("cannot open pid file %s: %s", path, strerror(errno));
 854         fprintf(f, "%d\n", getpid());
 855         fclose(f);
 856 }
 857
 858 static int serve(int port, struct passwd *pass, gid_t gid)
 859 {
 860         int socknum, *socklist;
 861
 862         socknum = socksetup(port, &socklist);
 863         if (socknum == 0)
 864                 die("unable to allocate any listen sockets on port %u", port);
 865
 866         if (pass && gid &&
 867             (initgroups(pass->pw_name, gid) || setgid (gid) ||
 868              setuid(pass->pw_uid)))
 869                 die("cannot drop privileges");
 870
 871         return service_loop(socknum, socklist);
 872 }
 873
 874 int main(int argc, char **argv)
 875 {
 876         int port = DEFAULT_GIT_PORT;
 877         int inetd_mode = 0;
 878         const char *pid_file = NULL, *user_name = NULL, *group_name = NULL;
 879         int detach = 0;
 880         struct passwd *pass = NULL;
 881         struct group *group;
 882         gid_t gid = 0;
 883         int i;
 884
 885         /* Without this we cannot rely on waitpid() to tell
 886          * what happened to our children.
 887          */
 888         signal(SIGCHLD, SIG_DFL);
 889
 890         for (i = 1; i < argc; i++) {
 891                 char *arg = argv[i];
 892
 893                 if (!strncmp(arg, "--port=", 7)) {
 894                         char *end;
 895                         unsigned long n;
 896                         n = strtoul(arg+7, &end, 0);
 897                         if (arg[7] && !*end) {
 898                                 port = n;
 899                                 continue;
 900                         }
 901                 }
 902                 if (!strcmp(arg, "--inetd")) {
 903                         inetd_mode = 1;
 904                         log_syslog = 1;
 905                         continue;
 906                 }
 907                 if (!strcmp(arg, "--verbose")) {
 908                         verbose = 1;
 909                         continue;
 910                 }
 911                 if (!strcmp(arg, "--syslog")) {
 912                         log_syslog = 1;
 913                         continue;
 914                 }
 915                 if (!strcmp(arg, "--export-all")) {
 916                         export_all_trees = 1;
 917                         continue;
 918                 }
 919                 if (!strncmp(arg, "--timeout=", 10)) {
 920                         timeout = atoi(arg+10);
 921                         continue;
 922                 }
 923                 if (!strncmp(arg, "--init-timeout=", 15)) {
 924                         init_timeout = atoi(arg+15);
 925                         continue;
 926                 }
 927                 if (!strcmp(arg, "--strict-paths")) {
 928                         strict_paths = 1;
 929                         continue;
 930                 }
 931                 if (!strncmp(arg, "--base-path=", 12)) {
 932                         base_path = arg+12;
 933                         continue;
 934                 }
 935                 if (!strncmp(arg, "--interpolated-path=", 20)) {
 936                         interpolated_path = arg+20;
 937                         continue;
 938                 }
 939                 if (!strcmp(arg, "--reuseaddr")) {
 940                         reuseaddr = 1;
 941                         continue;
 942                 }
 943                 if (!strcmp(arg, "--user-path")) {
 944                         user_path = "";
 945                         continue;
 946                 }
 947                 if (!strncmp(arg, "--user-path=", 12)) {
 948                         user_path = arg + 12;
 949                         continue;
 950                 }
 951                 if (!strncmp(arg, "--pid-file=", 11)) {
 952                         pid_file = arg + 11;
 953                         continue;
 954                 }
 955                 if (!strcmp(arg, "--detach")) {
 956                         detach = 1;
 957                         log_syslog = 1;
 958                         continue;
 959                 }
 960                 if (!strncmp(arg, "--user=", 7)) {
 961                         user_name = arg + 7;
 962                         continue;
 963                 }
 964                 if (!strncmp(arg, "--group=", 8)) {
 965                         group_name = arg + 8;
 966                         continue;
 967                 }
 968                 if (!strncmp(arg, "--enable=", 9)) {
 969                         enable_service(arg + 9, 1);
 970                         continue;
 971                 }
 972                 if (!strncmp(arg, "--disable=", 10)) {
 973                         enable_service(arg + 10, 0);
 974                         continue;
 975                 }
 976                 if (!strncmp(arg, "--allow-override=", 17)) {
 977                         make_service_overridable(arg + 17, 1);
 978                         continue;
 979                 }
 980                 if (!strncmp(arg, "--forbid-override=", 18)) {
 981                         make_service_overridable(arg + 18, 0);
 982                         continue;
 983                 }
 984                 if (!strcmp(arg, "--")) {
 985                         ok_paths = &argv[i+1];
 986                         break;
 987                 } else if (arg[0] != '-') {
 988                         ok_paths = &argv[i];
 989                         break;
 990                 }
 991
 992                 usage(daemon_usage);
 993         }
 994
 995         if (inetd_mode && (group_name || user_name))
 996                 die("--user and --group are incompatible with --inetd");
 997
 998         if (group_name && !user_name)
 999                 die("--group supplied without --user");
1000
1001         if (user_name) {
1002                 pass = getpwnam(user_name);
1003                 if (!pass)
1004                         die("user not found - %s", user_name);
1005
1006                 if (!group_name)
1007                         gid = pass->pw_gid;
1008                 else {
1009                         group = getgrnam(group_name);
1010                         if (!group)
1011                                 die("group not found - %s", group_name);
1012
1013                         gid = group->gr_gid;
1014                 }
1015         }
1016
1017         if (log_syslog) {
1018                 openlog("git-daemon", 0, LOG_DAEMON);
1019                 set_die_routine(daemon_die);
1020         }
1021
1022         if (strict_paths && (!ok_paths || !*ok_paths))
1023                 die("option --strict-paths requires a whitelist");
1024
1025         if (inetd_mode) {
1026                 struct sockaddr_storage ss;
1027                 struct sockaddr *peer = (struct sockaddr *)&ss;
1028                 socklen_t slen = sizeof(ss);
1029
1030                 freopen("/dev/null", "w", stderr);
1031
1032                 if (getpeername(0, peer, &slen))
1033                         peer = NULL;
1034
1035                 return execute(peer);
1036         }
1037
1038         if (detach)
1039                 daemonize();
1040         else
1041                 sanitize_stdfds();
1042
1043         if (pid_file)
1044                 store_pid(pid_file);
1045
1046         return serve(port, pass, gid);
1047 }