daemon.c

   1 #include "cache.h"
   2 #include "pkt-line.h"
   3 #include "run-command.h"
   4 #include "strbuf.h"
   5 #include "string-list.h"
   6
   7 #ifdef NO_INITGROUPS
   8 #define initgroups(x, y) (0) /* nothing */
   9 #endif
  10
  11 static int log_syslog;
  12 static int verbose;
  13 static int reuseaddr;
  14 static int informative_errors;
  15
  16 static const char daemon_usage[] =
  17 "git daemon [--verbose] [--syslog] [--export-all]\n"
  18 "           [--timeout=<n>] [--init-timeout=<n>] [--max-connections=<n>]\n"
  19 "           [--strict-paths] [--base-path=<path>] [--base-path-relaxed]\n"
  20 "           [--user-path | --user-path=<path>]\n"
  21 "           [--interpolated-path=<path>]\n"
  22 "           [--reuseaddr] [--pid-file=<file>]\n"
  23 "           [--(enable|disable|allow-override|forbid-override)=<service>]\n"
  24 "           [--access-hook=<path>]\n"
  25 "           [--inetd | [--listen=<host_or_ipaddr>] [--port=<n>]\n"
  26 "                      [--detach] [--user=<user> [--group=<group>]]\n"
  27 "           [<directory>...]";
  28
  29 /* List of acceptable pathname prefixes */
  30 static const char **ok_paths;
  31 static int strict_paths;
  32
  33 /* If this is set, git-daemon-export-ok is not required */
  34 static int export_all_trees;
  35
  36 /* Take all paths relative to this one if non-NULL */
  37 static const char *base_path;
  38 static const char *interpolated_path;
  39 static int base_path_relaxed;
  40
  41 /* If defined, ~user notation is allowed and the string is inserted
  42  * after ~user/.  E.g. a request to git://host/~alice/frotz would
  43  * go to /home/alice/pub_git/frotz with --user-path=pub_git.
  44  */
  45 static const char *user_path;
  46
  47 /* Timeout, and initial timeout */
  48 static unsigned int timeout;
  49 static unsigned int init_timeout;
  50
  51 struct hostinfo {
  52         struct strbuf hostname;
  53         struct strbuf canon_hostname;
  54         struct strbuf ip_address;
  55         struct strbuf tcp_port;
  56         unsigned int hostname_lookup_done:1;
  57         unsigned int saw_extended_args:1;
  58 };
  59
  60 static void lookup_hostname(struct hostinfo *hi);
  61
  62 static const char *get_canon_hostname(struct hostinfo *hi)
  63 {
  64         lookup_hostname(hi);
  65         return hi->canon_hostname.buf;
  66 }
  67
  68 static const char *get_ip_address(struct hostinfo *hi)
  69 {
  70         lookup_hostname(hi);
  71         return hi->ip_address.buf;
  72 }
  73
  74 static void logreport(int priority, const char *err, va_list params)
  75 {
  76         if (log_syslog) {
  77                 char buf[1024];
  78                 vsnprintf(buf, sizeof(buf), err, params);
  79                 syslog(priority, "%s", buf);
  80         } else {
  81                 /*
  82                  * Since stderr is set to buffered mode, the
  83                  * logging of different processes will not overlap
  84                  * unless they overflow the (rather big) buffers.
  85                  */
  86                 fprintf(stderr, "[%"PRIuMAX"] ", (uintmax_t)getpid());
  87                 vfprintf(stderr, err, params);
  88                 fputc('\n', stderr);
  89                 fflush(stderr);
  90         }
  91 }
  92
  93 __attribute__((format (printf, 1, 2)))
  94 static void logerror(const char *err, ...)
  95 {
  96         va_list params;
  97         va_start(params, err);
  98         logreport(LOG_ERR, err, params);
  99         va_end(params);
 100 }
 101
 102 __attribute__((format (printf, 1, 2)))
 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 struct expand_path_context {
 120         const char *directory;
 121         struct hostinfo *hostinfo;
 122 };
 123
 124 static size_t expand_path(struct strbuf *sb, const char *placeholder, void *ctx)
 125 {
 126         struct expand_path_context *context = ctx;
 127         struct hostinfo *hi = context->hostinfo;
 128
 129         switch (placeholder[0]) {
 130         case 'H':
 131                 strbuf_addbuf(sb, &hi->hostname);
 132                 return 1;
 133         case 'C':
 134                 if (placeholder[1] == 'H') {
 135                         strbuf_addstr(sb, get_canon_hostname(hi));
 136                         return 2;
 137                 }
 138                 break;
 139         case 'I':
 140                 if (placeholder[1] == 'P') {
 141                         strbuf_addstr(sb, get_ip_address(hi));
 142                         return 2;
 143                 }
 144                 break;
 145         case 'P':
 146                 strbuf_addbuf(sb, &hi->tcp_port);
 147                 return 1;
 148         case 'D':
 149                 strbuf_addstr(sb, context->directory);
 150                 return 1;
 151         }
 152         return 0;
 153 }
 154
 155 static const char *path_ok(const char *directory, struct hostinfo *hi)
 156 {
 157         static char rpath[PATH_MAX];
 158         static char interp_path[PATH_MAX];
 159         size_t rlen;
 160         const char *path;
 161         const char *dir;
 162
 163         dir = directory;
 164
 165         if (daemon_avoid_alias(dir)) {
 166                 logerror("'%s': aliased", dir);
 167                 return NULL;
 168         }
 169
 170         if (*dir == '~') {
 171                 if (!user_path) {
 172                         logerror("'%s': User-path not allowed", dir);
 173                         return NULL;
 174                 }
 175                 if (*user_path) {
 176                         /* Got either "~alice" or "~alice/foo";
 177                          * rewrite them to "~alice/%s" or
 178                          * "~alice/%s/foo".
 179                          */
 180                         int namlen, restlen = strlen(dir);
 181                         const char *slash = strchr(dir, '/');
 182                         if (!slash)
 183                                 slash = dir + restlen;
 184                         namlen = slash - dir;
 185                         restlen -= namlen;
 186                         loginfo("userpath <%s>, request <%s>, namlen %d, restlen %d, slash <%s>", user_path, dir, namlen, restlen, slash);
 187                         rlen = snprintf(rpath, sizeof(rpath), "%.*s/%s%.*s",
 188                                         namlen, dir, user_path, restlen, slash);
 189                         if (rlen >= sizeof(rpath)) {
 190                                 logerror("user-path too large: %s", rpath);
 191                                 return NULL;
 192                         }
 193                         dir = rpath;
 194                 }
 195         }
 196         else if (interpolated_path && hi->saw_extended_args) {
 197                 struct strbuf expanded_path = STRBUF_INIT;
 198                 struct expand_path_context context;
 199
 200                 context.directory = directory;
 201                 context.hostinfo = hi;
 202
 203                 if (*dir != '/') {
 204                         /* Allow only absolute */
 205                         logerror("'%s': Non-absolute path denied (interpolated-path active)", dir);
 206                         return NULL;
 207                 }
 208
 209                 strbuf_expand(&expanded_path, interpolated_path,
 210                               expand_path, &context);
 211
 212                 rlen = strlcpy(interp_path, expanded_path.buf,
 213                                sizeof(interp_path));
 214                 if (rlen >= sizeof(interp_path)) {
 215                         logerror("interpolated path too large: %s",
 216                                  interp_path);
 217                         return NULL;
 218                 }
 219
 220                 strbuf_release(&expanded_path);
 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                 rlen = snprintf(rpath, sizeof(rpath), "%s%s", base_path, dir);
 232                 if (rlen >= sizeof(rpath)) {
 233                         logerror("base-path too large: %s", rpath);
 234                         return NULL;
 235                 }
 236                 dir = rpath;
 237         }
 238
 239         path = enter_repo(dir, strict_paths);
 240         if (!path && base_path && base_path_relaxed) {
 241                 /*
 242                  * if we fail and base_path_relaxed is enabled, try without
 243                  * prefixing the base path
 244                  */
 245                 dir = directory;
 246                 path = enter_repo(dir, strict_paths);
 247         }
 248
 249         if (!path) {
 250                 logerror("'%s' does not appear to be a git repository", dir);
 251                 return NULL;
 252         }
 253
 254         if ( ok_paths && *ok_paths ) {
 255                 const char **pp;
 256                 int pathlen = strlen(path);
 257
 258                 /* The validation is done on the paths after enter_repo
 259                  * appends optional {.git,.git/.git} and friends, but
 260                  * it does not use getcwd().  So if your /pub is
 261                  * a symlink to /mnt/pub, you can whitelist /pub and
 262                  * do not have to say /mnt/pub.
 263                  * Do not say /pub/.
 264                  */
 265                 for ( pp = ok_paths ; *pp ; pp++ ) {
 266                         int len = strlen(*pp);
 267                         if (len <= pathlen &&
 268                             !memcmp(*pp, path, len) &&
 269                             (path[len] == '\0' ||
 270                              (!strict_paths && path[len] == '/')))
 271                                 return path;
 272                 }
 273         }
 274         else {
 275                 /* be backwards compatible */
 276                 if (!strict_paths)
 277                         return path;
 278         }
 279
 280         logerror("'%s': not in whitelist", path);
 281         return NULL;            /* Fallthrough. Deny by default */
 282 }
 283
 284 typedef int (*daemon_service_fn)(void);
 285 struct daemon_service {
 286         const char *name;
 287         const char *config_name;
 288         daemon_service_fn fn;
 289         int enabled;
 290         int overridable;
 291 };
 292
 293 static int daemon_error(const char *dir, const char *msg)
 294 {
 295         if (!informative_errors)
 296                 msg = "access denied or repository not exported";
 297         packet_write_fmt(1, "ERR %s: %s", msg, dir);
 298         return -1;
 299 }
 300
 301 static const char *access_hook;
 302
 303 static int run_access_hook(struct daemon_service *service, const char *dir,
 304                            const char *path, struct hostinfo *hi)
 305 {
 306         struct child_process child = CHILD_PROCESS_INIT;
 307         struct strbuf buf = STRBUF_INIT;
 308         const char *argv[8];
 309         const char **arg = argv;
 310         char *eol;
 311         int seen_errors = 0;
 312
 313         *arg++ = access_hook;
 314         *arg++ = service->name;
 315         *arg++ = path;
 316         *arg++ = hi->hostname.buf;
 317         *arg++ = get_canon_hostname(hi);
 318         *arg++ = get_ip_address(hi);
 319         *arg++ = hi->tcp_port.buf;
 320         *arg = NULL;
 321
 322         child.use_shell = 1;
 323         child.argv = argv;
 324         child.no_stdin = 1;
 325         child.no_stderr = 1;
 326         child.out = -1;
 327         if (start_command(&child)) {
 328                 logerror("daemon access hook '%s' failed to start",
 329                          access_hook);
 330                 goto error_return;
 331         }
 332         if (strbuf_read(&buf, child.out, 0) < 0) {
 333                 logerror("failed to read from pipe to daemon access hook '%s'",
 334                          access_hook);
 335                 strbuf_reset(&buf);
 336                 seen_errors = 1;
 337         }
 338         if (close(child.out) < 0) {
 339                 logerror("failed to close pipe to daemon access hook '%s'",
 340                          access_hook);
 341                 seen_errors = 1;
 342         }
 343         if (finish_command(&child))
 344                 seen_errors = 1;
 345
 346         if (!seen_errors) {
 347                 strbuf_release(&buf);
 348                 return 0;
 349         }
 350
 351 error_return:
 352         strbuf_ltrim(&buf);
 353         if (!buf.len)
 354                 strbuf_addstr(&buf, "service rejected");
 355         eol = strchr(buf.buf, '\n');
 356         if (eol)
 357                 *eol = '\0';
 358         errno = EACCES;
 359         daemon_error(dir, buf.buf);
 360         strbuf_release(&buf);
 361         return -1;
 362 }
 363
 364 static int run_service(const char *dir, struct daemon_service *service,
 365                        struct hostinfo *hi)
 366 {
 367         const char *path;
 368         int enabled = service->enabled;
 369         struct strbuf var = STRBUF_INIT;
 370
 371         loginfo("Request %s for '%s'", service->name, dir);
 372
 373         if (!enabled && !service->overridable) {
 374                 logerror("'%s': service not enabled.", service->name);
 375                 errno = EACCES;
 376                 return daemon_error(dir, "service not enabled");
 377         }
 378
 379         if (!(path = path_ok(dir, hi)))
 380                 return daemon_error(dir, "no such repository");
 381
 382         /*
 383          * Security on the cheap.
 384          *
 385          * We want a readable HEAD, usable "objects" directory, and
 386          * a "git-daemon-export-ok" flag that says that the other side
 387          * is ok with us doing this.
 388          *
 389          * path_ok() uses enter_repo() and does whitelist checking.
 390          * We only need to make sure the repository is exported.
 391          */
 392
 393         if (!export_all_trees && access("git-daemon-export-ok", F_OK)) {
 394                 logerror("'%s': repository not exported.", path);
 395                 errno = EACCES;
 396                 return daemon_error(dir, "repository not exported");
 397         }
 398
 399         if (service->overridable) {
 400                 strbuf_addf(&var, "daemon.%s", service->config_name);
 401                 git_config_get_bool(var.buf, &enabled);
 402                 strbuf_release(&var);
 403         }
 404         if (!enabled) {
 405                 logerror("'%s': service not enabled for '%s'",
 406                          service->name, path);
 407                 errno = EACCES;
 408                 return daemon_error(dir, "service not enabled");
 409         }
 410
 411         /*
 412          * Optionally, a hook can choose to deny access to the
 413          * repository depending on the phase of the moon.
 414          */
 415         if (access_hook && run_access_hook(service, dir, path, hi))
 416                 return -1;
 417
 418         /*
 419          * We'll ignore SIGTERM from now on, we have a
 420          * good client.
 421          */
 422         signal(SIGTERM, SIG_IGN);
 423
 424         return service->fn();
 425 }
 426
 427 static void copy_to_log(int fd)
 428 {
 429         struct strbuf line = STRBUF_INIT;
 430         FILE *fp;
 431
 432         fp = fdopen(fd, "r");
 433         if (fp == NULL) {
 434                 logerror("fdopen of error channel failed");
 435                 close(fd);
 436                 return;
 437         }
 438
 439         while (strbuf_getline_lf(&line, fp) != EOF) {
 440                 logerror("%s", line.buf);
 441                 strbuf_setlen(&line, 0);
 442         }
 443
 444         strbuf_release(&line);
 445         fclose(fp);
 446 }
 447
 448 static int run_service_command(struct child_process *cld)
 449 {
 450         argv_array_push(&cld->args, ".");
 451         cld->git_cmd = 1;
 452         cld->err = -1;
 453         if (start_command(cld))
 454                 return -1;
 455
 456         close(0);
 457         close(1);
 458
 459         copy_to_log(cld->err);
 460
 461         return finish_command(cld);
 462 }
 463
 464 static int upload_pack(void)
 465 {
 466         struct child_process cld = CHILD_PROCESS_INIT;
 467         argv_array_pushl(&cld.args, "upload-pack", "--strict", NULL);
 468         argv_array_pushf(&cld.args, "--timeout=%u", timeout);
 469         return run_service_command(&cld);
 470 }
 471
 472 static int upload_archive(void)
 473 {
 474         struct child_process cld = CHILD_PROCESS_INIT;
 475         argv_array_push(&cld.args, "upload-archive");
 476         return run_service_command(&cld);
 477 }
 478
 479 static int receive_pack(void)
 480 {
 481         struct child_process cld = CHILD_PROCESS_INIT;
 482         argv_array_push(&cld.args, "receive-pack");
 483         return run_service_command(&cld);
 484 }
 485
 486 static struct daemon_service daemon_service[] = {
 487         { "upload-archive", "uploadarch", upload_archive, 0, 1 },
 488         { "upload-pack", "uploadpack", upload_pack, 1, 1 },
 489         { "receive-pack", "receivepack", receive_pack, 0, 1 },
 490 };
 491
 492 static void enable_service(const char *name, int ena)
 493 {
 494         int i;
 495         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 496                 if (!strcmp(daemon_service[i].name, name)) {
 497                         daemon_service[i].enabled = ena;
 498                         return;
 499                 }
 500         }
 501         die("No such service %s", name);
 502 }
 503
 504 static void make_service_overridable(const char *name, int ena)
 505 {
 506         int i;
 507         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 508                 if (!strcmp(daemon_service[i].name, name)) {
 509                         daemon_service[i].overridable = ena;
 510                         return;
 511                 }
 512         }
 513         die("No such service %s", name);
 514 }
 515
 516 static void parse_host_and_port(char *hostport, char **host,
 517         char **port)
 518 {
 519         if (*hostport == '[') {
 520                 char *end;
 521
 522                 end = strchr(hostport, ']');
 523                 if (!end)
 524                         die("Invalid request ('[' without ']')");
 525                 *end = '\0';
 526                 *host = hostport + 1;
 527                 if (!end[1])
 528                         *port = NULL;
 529                 else if (end[1] == ':')
 530                         *port = end + 2;
 531                 else
 532                         die("Garbage after end of host part");
 533         } else {
 534                 *host = hostport;
 535                 *port = strrchr(hostport, ':');
 536                 if (*port) {
 537                         **port = '\0';
 538                         ++*port;
 539                 }
 540         }
 541 }
 542
 543 /*
 544  * Sanitize a string from the client so that it's OK to be inserted into a
 545  * filesystem path. Specifically, we disallow slashes, runs of "..", and
 546  * trailing and leading dots, which means that the client cannot escape
 547  * our base path via ".." traversal.
 548  */
 549 static void sanitize_client(struct strbuf *out, const char *in)
 550 {
 551         for (; *in; in++) {
 552                 if (*in == '/')
 553                         continue;
 554                 if (*in == '.' && (!out->len || out->buf[out->len - 1] == '.'))
 555                         continue;
 556                 strbuf_addch(out, *in);
 557         }
 558
 559         while (out->len && out->buf[out->len - 1] == '.')
 560                 strbuf_setlen(out, out->len - 1);
 561 }
 562
 563 /*
 564  * Like sanitize_client, but we also perform any canonicalization
 565  * to make life easier on the admin.
 566  */
 567 static void canonicalize_client(struct strbuf *out, const char *in)
 568 {
 569         sanitize_client(out, in);
 570         strbuf_tolower(out);
 571 }
 572
 573 /*
 574  * Read the host as supplied by the client connection.
 575  */
 576 static void parse_host_arg(struct hostinfo *hi, char *extra_args, int buflen)
 577 {
 578         char *val;
 579         int vallen;
 580         char *end = extra_args + buflen;
 581
 582         if (extra_args < end && *extra_args) {
 583                 hi->saw_extended_args = 1;
 584                 if (strncasecmp("host=", extra_args, 5) == 0) {
 585                         val = extra_args + 5;
 586                         vallen = strlen(val) + 1;
 587                         if (*val) {
 588                                 /* Split <host>:<port> at colon. */
 589                                 char *host;
 590                                 char *port;
 591                                 parse_host_and_port(val, &host, &port);
 592                                 if (port)
 593                                         sanitize_client(&hi->tcp_port, port);
 594                                 canonicalize_client(&hi->hostname, host);
 595                                 hi->hostname_lookup_done = 0;
 596                         }
 597
 598                         /* On to the next one */
 599                         extra_args = val + vallen;
 600                 }
 601                 if (extra_args < end && *extra_args)
 602                         die("Invalid request");
 603         }
 604 }
 605
 606 /*
 607  * Locate canonical hostname and its IP address.
 608  */
 609 static void lookup_hostname(struct hostinfo *hi)
 610 {
 611         if (!hi->hostname_lookup_done && hi->hostname.len) {
 612 #ifndef NO_IPV6
 613                 struct addrinfo hints;
 614                 struct addrinfo *ai;
 615                 int gai;
 616                 static char addrbuf[HOST_NAME_MAX + 1];
 617
 618                 memset(&hints, 0, sizeof(hints));
 619                 hints.ai_flags = AI_CANONNAME;
 620
 621                 gai = getaddrinfo(hi->hostname.buf, NULL, &hints, &ai);
 622                 if (!gai) {
 623                         struct sockaddr_in *sin_addr = (void *)ai->ai_addr;
 624
 625                         inet_ntop(AF_INET, &sin_addr->sin_addr,
 626                                   addrbuf, sizeof(addrbuf));
 627                         strbuf_addstr(&hi->ip_address, addrbuf);
 628
 629                         if (ai->ai_canonname)
 630                                 sanitize_client(&hi->canon_hostname,
 631                                                 ai->ai_canonname);
 632                         else
 633                                 strbuf_addbuf(&hi->canon_hostname,
 634                                               &hi->ip_address);
 635
 636                         freeaddrinfo(ai);
 637                 }
 638 #else
 639                 struct hostent *hent;
 640                 struct sockaddr_in sa;
 641                 char **ap;
 642                 static char addrbuf[HOST_NAME_MAX + 1];
 643
 644                 hent = gethostbyname(hi->hostname.buf);
 645                 if (hent) {
 646                         ap = hent->h_addr_list;
 647                         memset(&sa, 0, sizeof sa);
 648                         sa.sin_family = hent->h_addrtype;
 649                         sa.sin_port = htons(0);
 650                         memcpy(&sa.sin_addr, *ap, hent->h_length);
 651
 652                         inet_ntop(hent->h_addrtype, &sa.sin_addr,
 653                                   addrbuf, sizeof(addrbuf));
 654
 655                         sanitize_client(&hi->canon_hostname, hent->h_name);
 656                         strbuf_addstr(&hi->ip_address, addrbuf);
 657                 }
 658 #endif
 659                 hi->hostname_lookup_done = 1;
 660         }
 661 }
 662
 663 static void hostinfo_init(struct hostinfo *hi)
 664 {
 665         memset(hi, 0, sizeof(*hi));
 666         strbuf_init(&hi->hostname, 0);
 667         strbuf_init(&hi->canon_hostname, 0);
 668         strbuf_init(&hi->ip_address, 0);
 669         strbuf_init(&hi->tcp_port, 0);
 670 }
 671
 672 static void hostinfo_clear(struct hostinfo *hi)
 673 {
 674         strbuf_release(&hi->hostname);
 675         strbuf_release(&hi->canon_hostname);
 676         strbuf_release(&hi->ip_address);
 677         strbuf_release(&hi->tcp_port);
 678 }
 679
 680 static void set_keep_alive(int sockfd)
 681 {
 682         int ka = 1;
 683
 684         if (setsockopt(sockfd, SOL_SOCKET, SO_KEEPALIVE, &ka, sizeof(ka)) < 0) {
 685                 if (errno != ENOTSOCK)
 686                         logerror("unable to set SO_KEEPALIVE on socket: %s",
 687                                 strerror(errno));
 688         }
 689 }
 690
 691 static int execute(void)
 692 {
 693         char *line = packet_buffer;
 694         int pktlen, len, i;
 695         char *addr = getenv("REMOTE_ADDR"), *port = getenv("REMOTE_PORT");
 696         struct hostinfo hi;
 697
 698         hostinfo_init(&hi);
 699
 700         if (addr)
 701                 loginfo("Connection from %s:%s", addr, port);
 702
 703         set_keep_alive(0);
 704         alarm(init_timeout ? init_timeout : timeout);
 705         pktlen = packet_read(0, NULL, NULL, packet_buffer, sizeof(packet_buffer), 0);
 706         alarm(0);
 707
 708         len = strlen(line);
 709         if (pktlen != len)
 710                 loginfo("Extended attributes (%d bytes) exist <%.*s>",
 711                         (int) pktlen - len,
 712                         (int) pktlen - len, line + len + 1);
 713         if (len && line[len-1] == '\n') {
 714                 line[--len] = 0;
 715                 pktlen--;
 716         }
 717
 718         if (len != pktlen)
 719                 parse_host_arg(&hi, line + len + 1, pktlen - len - 1);
 720
 721         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 722                 struct daemon_service *s = &(daemon_service[i]);
 723                 const char *arg;
 724
 725                 if (skip_prefix(line, "git-", &arg) &&
 726                     skip_prefix(arg, s->name, &arg) &&
 727                     *arg++ == ' ') {
 728                         /*
 729                          * Note: The directory here is probably context sensitive,
 730                          * and might depend on the actual service being performed.
 731                          */
 732                         int rc = run_service(arg, s, &hi);
 733                         hostinfo_clear(&hi);
 734                         return rc;
 735                 }
 736         }
 737
 738         hostinfo_clear(&hi);
 739         logerror("Protocol error: '%s'", line);
 740         return -1;
 741 }
 742
 743 static int addrcmp(const struct sockaddr_storage *s1,
 744     const struct sockaddr_storage *s2)
 745 {
 746         const struct sockaddr *sa1 = (const struct sockaddr*) s1;
 747         const struct sockaddr *sa2 = (const struct sockaddr*) s2;
 748
 749         if (sa1->sa_family != sa2->sa_family)
 750                 return sa1->sa_family - sa2->sa_family;
 751         if (sa1->sa_family == AF_INET)
 752                 return memcmp(&((struct sockaddr_in *)s1)->sin_addr,
 753                     &((struct sockaddr_in *)s2)->sin_addr,
 754                     sizeof(struct in_addr));
 755 #ifndef NO_IPV6
 756         if (sa1->sa_family == AF_INET6)
 757                 return memcmp(&((struct sockaddr_in6 *)s1)->sin6_addr,
 758                     &((struct sockaddr_in6 *)s2)->sin6_addr,
 759                     sizeof(struct in6_addr));
 760 #endif
 761         return 0;
 762 }
 763
 764 static int max_connections = 32;
 765
 766 static unsigned int live_children;
 767
 768 static struct child {
 769         struct child *next;
 770         struct child_process cld;
 771         struct sockaddr_storage address;
 772 } *firstborn;
 773
 774 static void add_child(struct child_process *cld, struct sockaddr *addr, socklen_t addrlen)
 775 {
 776         struct child *newborn, **cradle;
 777
 778         newborn = xcalloc(1, sizeof(*newborn));
 779         live_children++;
 780         memcpy(&newborn->cld, cld, sizeof(*cld));
 781         memcpy(&newborn->address, addr, addrlen);
 782         for (cradle = &firstborn; *cradle; cradle = &(*cradle)->next)
 783                 if (!addrcmp(&(*cradle)->address, &newborn->address))
 784                         break;
 785         newborn->next = *cradle;
 786         *cradle = newborn;
 787 }
 788
 789 /*
 790  * This gets called if the number of connections grows
 791  * past "max_connections".
 792  *
 793  * We kill the newest connection from a duplicate IP.
 794  */
 795 static void kill_some_child(void)
 796 {
 797         const struct child *blanket, *next;
 798
 799         if (!(blanket = firstborn))
 800                 return;
 801
 802         for (; (next = blanket->next); blanket = next)
 803                 if (!addrcmp(&blanket->address, &next->address)) {
 804                         kill(blanket->cld.pid, SIGTERM);
 805                         break;
 806                 }
 807 }
 808
 809 static void check_dead_children(void)
 810 {
 811         int status;
 812         pid_t pid;
 813
 814         struct child **cradle, *blanket;
 815         for (cradle = &firstborn; (blanket = *cradle);)
 816                 if ((pid = waitpid(blanket->cld.pid, &status, WNOHANG)) > 1) {
 817                         const char *dead = "";
 818                         if (status)
 819                                 dead = " (with error)";
 820                         loginfo("[%"PRIuMAX"] Disconnected%s", (uintmax_t)pid, dead);
 821
 822                         /* remove the child */
 823                         *cradle = blanket->next;
 824                         live_children--;
 825                         child_process_clear(&blanket->cld);
 826                         free(blanket);
 827                 } else
 828                         cradle = &blanket->next;
 829 }
 830
 831 static struct argv_array cld_argv = ARGV_ARRAY_INIT;
 832 static void handle(int incoming, struct sockaddr *addr, socklen_t addrlen)
 833 {
 834         struct child_process cld = CHILD_PROCESS_INIT;
 835
 836         if (max_connections && live_children >= max_connections) {
 837                 kill_some_child();
 838                 sleep(1);  /* give it some time to die */
 839                 check_dead_children();
 840                 if (live_children >= max_connections) {
 841                         close(incoming);
 842                         logerror("Too many children, dropping connection");
 843                         return;
 844                 }
 845         }
 846
 847         if (addr->sa_family == AF_INET) {
 848                 char buf[128] = "";
 849                 struct sockaddr_in *sin_addr = (void *) addr;
 850                 inet_ntop(addr->sa_family, &sin_addr->sin_addr, buf, sizeof(buf));
 851                 argv_array_pushf(&cld.env_array, "REMOTE_ADDR=%s", buf);
 852                 argv_array_pushf(&cld.env_array, "REMOTE_PORT=%d",
 853                                  ntohs(sin_addr->sin_port));
 854 #ifndef NO_IPV6
 855         } else if (addr->sa_family == AF_INET6) {
 856                 char buf[128] = "";
 857                 struct sockaddr_in6 *sin6_addr = (void *) addr;
 858                 inet_ntop(AF_INET6, &sin6_addr->sin6_addr, buf, sizeof(buf));
 859                 argv_array_pushf(&cld.env_array, "REMOTE_ADDR=[%s]", buf);
 860                 argv_array_pushf(&cld.env_array, "REMOTE_PORT=%d",
 861                                  ntohs(sin6_addr->sin6_port));
 862 #endif
 863         }
 864
 865         cld.argv = cld_argv.argv;
 866         cld.in = incoming;
 867         cld.out = dup(incoming);
 868
 869         if (start_command(&cld))
 870                 logerror("unable to fork");
 871         else
 872                 add_child(&cld, addr, addrlen);
 873 }
 874
 875 static void child_handler(int signo)
 876 {
 877         /*
 878          * Otherwise empty handler because systemcalls will get interrupted
 879          * upon signal receipt
 880          * SysV needs the handler to be rearmed
 881          */
 882         signal(SIGCHLD, child_handler);
 883 }
 884
 885 static int set_reuse_addr(int sockfd)
 886 {
 887         int on = 1;
 888
 889         if (!reuseaddr)
 890                 return 0;
 891         return setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
 892                           &on, sizeof(on));
 893 }
 894
 895 struct socketlist {
 896         int *list;
 897         size_t nr;
 898         size_t alloc;
 899 };
 900
 901 static const char *ip2str(int family, struct sockaddr *sin, socklen_t len)
 902 {
 903 #ifdef NO_IPV6
 904         static char ip[INET_ADDRSTRLEN];
 905 #else
 906         static char ip[INET6_ADDRSTRLEN];
 907 #endif
 908
 909         switch (family) {
 910 #ifndef NO_IPV6
 911         case AF_INET6:
 912                 inet_ntop(family, &((struct sockaddr_in6*)sin)->sin6_addr, ip, len);
 913                 break;
 914 #endif
 915         case AF_INET:
 916                 inet_ntop(family, &((struct sockaddr_in*)sin)->sin_addr, ip, len);
 917                 break;
 918         default:
 919                 xsnprintf(ip, sizeof(ip), "<unknown>");
 920         }
 921         return ip;
 922 }
 923
 924 #ifndef NO_IPV6
 925
 926 static int setup_named_sock(char *listen_addr, int listen_port, struct socketlist *socklist)
 927 {
 928         int socknum = 0;
 929         char pbuf[NI_MAXSERV];
 930         struct addrinfo hints, *ai0, *ai;
 931         int gai;
 932         long flags;
 933
 934         xsnprintf(pbuf, sizeof(pbuf), "%d", listen_port);
 935         memset(&hints, 0, sizeof(hints));
 936         hints.ai_family = AF_UNSPEC;
 937         hints.ai_socktype = SOCK_STREAM;
 938         hints.ai_protocol = IPPROTO_TCP;
 939         hints.ai_flags = AI_PASSIVE;
 940
 941         gai = getaddrinfo(listen_addr, pbuf, &hints, &ai0);
 942         if (gai) {
 943                 logerror("getaddrinfo() for %s failed: %s", listen_addr, gai_strerror(gai));
 944                 return 0;
 945         }
 946
 947         for (ai = ai0; ai; ai = ai->ai_next) {
 948                 int sockfd;
 949
 950                 sockfd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
 951                 if (sockfd < 0)
 952                         continue;
 953                 if (sockfd >= FD_SETSIZE) {
 954                         logerror("Socket descriptor too large");
 955                         close(sockfd);
 956                         continue;
 957                 }
 958
 959 #ifdef IPV6_V6ONLY
 960                 if (ai->ai_family == AF_INET6) {
 961                         int on = 1;
 962                         setsockopt(sockfd, IPPROTO_IPV6, IPV6_V6ONLY,
 963                                    &on, sizeof(on));
 964                         /* Note: error is not fatal */
 965                 }
 966 #endif
 967
 968                 if (set_reuse_addr(sockfd)) {
 969                         logerror("Could not set SO_REUSEADDR: %s", strerror(errno));
 970                         close(sockfd);
 971                         continue;
 972                 }
 973
 974                 set_keep_alive(sockfd);
 975
 976                 if (bind(sockfd, ai->ai_addr, ai->ai_addrlen) < 0) {
 977                         logerror("Could not bind to %s: %s",
 978                                  ip2str(ai->ai_family, ai->ai_addr, ai->ai_addrlen),
 979                                  strerror(errno));
 980                         close(sockfd);
 981                         continue;       /* not fatal */
 982                 }
 983                 if (listen(sockfd, 5) < 0) {
 984                         logerror("Could not listen to %s: %s",
 985                                  ip2str(ai->ai_family, ai->ai_addr, ai->ai_addrlen),
 986                                  strerror(errno));
 987                         close(sockfd);
 988                         continue;       /* not fatal */
 989                 }
 990
 991                 flags = fcntl(sockfd, F_GETFD, 0);
 992                 if (flags >= 0)
 993                         fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
 994
 995                 ALLOC_GROW(socklist->list, socklist->nr + 1, socklist->alloc);
 996                 socklist->list[socklist->nr++] = sockfd;
 997                 socknum++;
 998         }
 999
1000         freeaddrinfo(ai0);
1001
1002         return socknum;
1003 }
1004
1005 #else /* NO_IPV6 */
1006
1007 static int setup_named_sock(char *listen_addr, int listen_port, struct socketlist *socklist)
1008 {
1009         struct sockaddr_in sin;
1010         int sockfd;
1011         long flags;
1012
1013         memset(&sin, 0, sizeof sin);
1014         sin.sin_family = AF_INET;
1015         sin.sin_port = htons(listen_port);
1016
1017         if (listen_addr) {
1018                 /* Well, host better be an IP address here. */
1019                 if (inet_pton(AF_INET, listen_addr, &sin.sin_addr.s_addr) <= 0)
1020                         return 0;
1021         } else {
1022                 sin.sin_addr.s_addr = htonl(INADDR_ANY);
1023         }
1024
1025         sockfd = socket(AF_INET, SOCK_STREAM, 0);
1026         if (sockfd < 0)
1027                 return 0;
1028
1029         if (set_reuse_addr(sockfd)) {
1030                 logerror("Could not set SO_REUSEADDR: %s", strerror(errno));
1031                 close(sockfd);
1032                 return 0;
1033         }
1034
1035         set_keep_alive(sockfd);
1036
1037         if ( bind(sockfd, (struct sockaddr *)&sin, sizeof sin) < 0 ) {
1038                 logerror("Could not bind to %s: %s",
1039                          ip2str(AF_INET, (struct sockaddr *)&sin, sizeof(sin)),
1040                          strerror(errno));
1041                 close(sockfd);
1042                 return 0;
1043         }
1044
1045         if (listen(sockfd, 5) < 0) {
1046                 logerror("Could not listen to %s: %s",
1047                          ip2str(AF_INET, (struct sockaddr *)&sin, sizeof(sin)),
1048                          strerror(errno));
1049                 close(sockfd);
1050                 return 0;
1051         }
1052
1053         flags = fcntl(sockfd, F_GETFD, 0);
1054         if (flags >= 0)
1055                 fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
1056
1057         ALLOC_GROW(socklist->list, socklist->nr + 1, socklist->alloc);
1058         socklist->list[socklist->nr++] = sockfd;
1059         return 1;
1060 }
1061
1062 #endif
1063
1064 static void socksetup(struct string_list *listen_addr, int listen_port, struct socketlist *socklist)
1065 {
1066         if (!listen_addr->nr)
1067                 setup_named_sock(NULL, listen_port, socklist);
1068         else {
1069                 int i, socknum;
1070                 for (i = 0; i < listen_addr->nr; i++) {
1071                         socknum = setup_named_sock(listen_addr->items[i].string,
1072                                                    listen_port, socklist);
1073
1074                         if (socknum == 0)
1075                                 logerror("unable to allocate any listen sockets for host %s on port %u",
1076                                          listen_addr->items[i].string, listen_port);
1077                 }
1078         }
1079 }
1080
1081 static int service_loop(struct socketlist *socklist)
1082 {
1083         struct pollfd *pfd;
1084         int i;
1085
1086         pfd = xcalloc(socklist->nr, sizeof(struct pollfd));
1087
1088         for (i = 0; i < socklist->nr; i++) {
1089                 pfd[i].fd = socklist->list[i];
1090                 pfd[i].events = POLLIN;
1091         }
1092
1093         signal(SIGCHLD, child_handler);
1094
1095         for (;;) {
1096                 int i;
1097
1098                 check_dead_children();
1099
1100                 if (poll(pfd, socklist->nr, -1) < 0) {
1101                         if (errno != EINTR) {
1102                                 logerror("Poll failed, resuming: %s",
1103                                       strerror(errno));
1104                                 sleep(1);
1105                         }
1106                         continue;
1107                 }
1108
1109                 for (i = 0; i < socklist->nr; i++) {
1110                         if (pfd[i].revents & POLLIN) {
1111                                 union {
1112                                         struct sockaddr sa;
1113                                         struct sockaddr_in sai;
1114 #ifndef NO_IPV6
1115                                         struct sockaddr_in6 sai6;
1116 #endif
1117                                 } ss;
1118                                 socklen_t sslen = sizeof(ss);
1119                                 int incoming = accept(pfd[i].fd, &ss.sa, &sslen);
1120                                 if (incoming < 0) {
1121                                         switch (errno) {
1122                                         case EAGAIN:
1123                                         case EINTR:
1124                                         case ECONNABORTED:
1125                                                 continue;
1126                                         default:
1127                                                 die_errno("accept returned");
1128                                         }
1129                                 }
1130                                 handle(incoming, &ss.sa, sslen);
1131                         }
1132                 }
1133         }
1134 }
1135
1136 #ifdef NO_POSIX_GOODIES
1137
1138 struct credentials;
1139
1140 static void drop_privileges(struct credentials *cred)
1141 {
1142         /* nothing */
1143 }
1144
1145 static struct credentials *prepare_credentials(const char *user_name,
1146     const char *group_name)
1147 {
1148         die("--user not supported on this platform");
1149 }
1150
1151 #else
1152
1153 struct credentials {
1154         struct passwd *pass;
1155         gid_t gid;
1156 };
1157
1158 static void drop_privileges(struct credentials *cred)
1159 {
1160         if (cred && (initgroups(cred->pass->pw_name, cred->gid) ||
1161             setgid (cred->gid) || setuid(cred->pass->pw_uid)))
1162                 die("cannot drop privileges");
1163 }
1164
1165 static struct credentials *prepare_credentials(const char *user_name,
1166     const char *group_name)
1167 {
1168         static struct credentials c;
1169
1170         c.pass = getpwnam(user_name);
1171         if (!c.pass)
1172                 die("user not found - %s", user_name);
1173
1174         if (!group_name)
1175                 c.gid = c.pass->pw_gid;
1176         else {
1177                 struct group *group = getgrnam(group_name);
1178                 if (!group)
1179                         die("group not found - %s", group_name);
1180
1181                 c.gid = group->gr_gid;
1182         }
1183
1184         return &c;
1185 }
1186 #endif
1187
1188 static int serve(struct string_list *listen_addr, int listen_port,
1189     struct credentials *cred)
1190 {
1191         struct socketlist socklist = { NULL, 0, 0 };
1192
1193         socksetup(listen_addr, listen_port, &socklist);
1194         if (socklist.nr == 0)
1195                 die("unable to allocate any listen sockets on port %u",
1196                     listen_port);
1197
1198         drop_privileges(cred);
1199
1200         loginfo("Ready to rumble");
1201
1202         return service_loop(&socklist);
1203 }
1204
1205 int cmd_main(int argc, const char **argv)
1206 {
1207         int listen_port = 0;
1208         struct string_list listen_addr = STRING_LIST_INIT_NODUP;
1209         int serve_mode = 0, inetd_mode = 0;
1210         const char *pid_file = NULL, *user_name = NULL, *group_name = NULL;
1211         int detach = 0;
1212         struct credentials *cred = NULL;
1213         int i;
1214
1215         for (i = 1; i < argc; i++) {
1216                 const char *arg = argv[i];
1217                 const char *v;
1218
1219                 if (skip_prefix(arg, "--listen=", &v)) {
1220                         string_list_append(&listen_addr, xstrdup_tolower(v));
1221                         continue;
1222                 }
1223                 if (skip_prefix(arg, "--port=", &v)) {
1224                         char *end;
1225                         unsigned long n;
1226                         n = strtoul(v, &end, 0);
1227                         if (*v && !*end) {
1228                                 listen_port = n;
1229                                 continue;
1230                         }
1231                 }
1232                 if (!strcmp(arg, "--serve")) {
1233                         serve_mode = 1;
1234                         continue;
1235                 }
1236                 if (!strcmp(arg, "--inetd")) {
1237                         inetd_mode = 1;
1238                         log_syslog = 1;
1239                         continue;
1240                 }
1241                 if (!strcmp(arg, "--verbose")) {
1242                         verbose = 1;
1243                         continue;
1244                 }
1245                 if (!strcmp(arg, "--syslog")) {
1246                         log_syslog = 1;
1247                         continue;
1248                 }
1249                 if (!strcmp(arg, "--export-all")) {
1250                         export_all_trees = 1;
1251                         continue;
1252                 }
1253                 if (skip_prefix(arg, "--access-hook=", &v)) {
1254                         access_hook = v;
1255                         continue;
1256                 }
1257                 if (skip_prefix(arg, "--timeout=", &v)) {
1258                         timeout = atoi(v);
1259                         continue;
1260                 }
1261                 if (skip_prefix(arg, "--init-timeout=", &v)) {
1262                         init_timeout = atoi(v);
1263                         continue;
1264                 }
1265                 if (skip_prefix(arg, "--max-connections=", &v)) {
1266                         max_connections = atoi(v);
1267                         if (max_connections < 0)
1268                                 max_connections = 0;            /* unlimited */
1269                         continue;
1270                 }
1271                 if (!strcmp(arg, "--strict-paths")) {
1272                         strict_paths = 1;
1273                         continue;
1274                 }
1275                 if (skip_prefix(arg, "--base-path=", &v)) {
1276                         base_path = v;
1277                         continue;
1278                 }
1279                 if (!strcmp(arg, "--base-path-relaxed")) {
1280                         base_path_relaxed = 1;
1281                         continue;
1282                 }
1283                 if (skip_prefix(arg, "--interpolated-path=", &v)) {
1284                         interpolated_path = v;
1285                         continue;
1286                 }
1287                 if (!strcmp(arg, "--reuseaddr")) {
1288                         reuseaddr = 1;
1289                         continue;
1290                 }
1291                 if (!strcmp(arg, "--user-path")) {
1292                         user_path = "";
1293                         continue;
1294                 }
1295                 if (skip_prefix(arg, "--user-path=", &v)) {
1296                         user_path = v;
1297                         continue;
1298                 }
1299                 if (skip_prefix(arg, "--pid-file=", &v)) {
1300                         pid_file = v;
1301                         continue;
1302                 }
1303                 if (!strcmp(arg, "--detach")) {
1304                         detach = 1;
1305                         log_syslog = 1;
1306                         continue;
1307                 }
1308                 if (skip_prefix(arg, "--user=", &v)) {
1309                         user_name = v;
1310                         continue;
1311                 }
1312                 if (skip_prefix(arg, "--group=", &v)) {
1313                         group_name = v;
1314                         continue;
1315                 }
1316                 if (skip_prefix(arg, "--enable=", &v)) {
1317                         enable_service(v, 1);
1318                         continue;
1319                 }
1320                 if (skip_prefix(arg, "--disable=", &v)) {
1321                         enable_service(v, 0);
1322                         continue;
1323                 }
1324                 if (skip_prefix(arg, "--allow-override=", &v)) {
1325                         make_service_overridable(v, 1);
1326                         continue;
1327                 }
1328                 if (skip_prefix(arg, "--forbid-override=", &v)) {
1329                         make_service_overridable(v, 0);
1330                         continue;
1331                 }
1332                 if (!strcmp(arg, "--informative-errors")) {
1333                         informative_errors = 1;
1334                         continue;
1335                 }
1336                 if (!strcmp(arg, "--no-informative-errors")) {
1337                         informative_errors = 0;
1338                         continue;
1339                 }
1340                 if (!strcmp(arg, "--")) {
1341                         ok_paths = &argv[i+1];
1342                         break;
1343                 } else if (arg[0] != '-') {
1344                         ok_paths = &argv[i];
1345                         break;
1346                 }
1347
1348                 usage(daemon_usage);
1349         }
1350
1351         if (log_syslog) {
1352                 openlog("git-daemon", LOG_PID, LOG_DAEMON);
1353                 set_die_routine(daemon_die);
1354         } else
1355                 /* avoid splitting a message in the middle */
1356                 setvbuf(stderr, NULL, _IOFBF, 4096);
1357
1358         if (inetd_mode && (detach || group_name || user_name))
1359                 die("--detach, --user and --group are incompatible with --inetd");
1360
1361         if (inetd_mode && (listen_port || (listen_addr.nr > 0)))
1362                 die("--listen= and --port= are incompatible with --inetd");
1363         else if (listen_port == 0)
1364                 listen_port = DEFAULT_GIT_PORT;
1365
1366         if (group_name && !user_name)
1367                 die("--group supplied without --user");
1368
1369         if (user_name)
1370                 cred = prepare_credentials(user_name, group_name);
1371
1372         if (strict_paths && (!ok_paths || !*ok_paths))
1373                 die("option --strict-paths requires a whitelist");
1374
1375         if (base_path && !is_directory(base_path))
1376                 die("base-path '%s' does not exist or is not a directory",
1377                     base_path);
1378
1379         if (inetd_mode) {
1380                 if (!freopen("/dev/null", "w", stderr))
1381                         die_errno("failed to redirect stderr to /dev/null");
1382         }
1383
1384         if (inetd_mode || serve_mode)
1385                 return execute();
1386
1387         if (detach) {
1388                 if (daemonize())
1389                         die("--detach not supported on this platform");
1390         }
1391
1392         if (pid_file)
1393                 write_file(pid_file, "%"PRIuMAX, (uintmax_t) getpid());
1394
1395         /* prepare argv for serving-processes */
1396         argv_array_push(&cld_argv, argv[0]); /* git-daemon */
1397         argv_array_push(&cld_argv, "--serve");
1398         for (i = 1; i < argc; ++i)
1399                 argv_array_push(&cld_argv, argv[i]);
1400
1401         return serve(&listen_addr, listen_port, cred);
1402 }