daemon.c

   1 #include "cache.h"
   2 #include "pkt-line.h"
   3 #include "exec_cmd.h"
   4 #include "run-command.h"
   5 #include "strbuf.h"
   6 #include "string-list.h"
   7
   8 #ifndef HOST_NAME_MAX
   9 #define HOST_NAME_MAX 256
  10 #endif
  11
  12 #ifdef NO_INITGROUPS
  13 #define initgroups(x, y) (0) /* nothing */
  14 #endif
  15
  16 static int log_syslog;
  17 static int verbose;
  18 static int reuseaddr;
  19 static int informative_errors;
  20
  21 static const char daemon_usage[] =
  22 "git daemon [--verbose] [--syslog] [--export-all]\n"
  23 "           [--timeout=<n>] [--init-timeout=<n>] [--max-connections=<n>]\n"
  24 "           [--strict-paths] [--base-path=<path>] [--base-path-relaxed]\n"
  25 "           [--user-path | --user-path=<path>]\n"
  26 "           [--interpolated-path=<path>]\n"
  27 "           [--reuseaddr] [--pid-file=<file>]\n"
  28 "           [--(enable|disable|allow-override|forbid-override)=<service>]\n"
  29 "           [--access-hook=<path>]\n"
  30 "           [--inetd | [--listen=<host_or_ipaddr>] [--port=<n>]\n"
  31 "                      [--detach] [--user=<user> [--group=<group>]]\n"
  32 "           [<directory>...]";
  33
  34 /* List of acceptable pathname prefixes */
  35 static char **ok_paths;
  36 static int strict_paths;
  37
  38 /* If this is set, git-daemon-export-ok is not required */
  39 static int export_all_trees;
  40
  41 /* Take all paths relative to this one if non-NULL */
  42 static const char *base_path;
  43 static const char *interpolated_path;
  44 static int base_path_relaxed;
  45
  46 /* Flag indicating client sent extra args. */
  47 static int saw_extended_args;
  48
  49 /* If defined, ~user notation is allowed and the string is inserted
  50  * after ~user/.  E.g. a request to git://host/~alice/frotz would
  51  * go to /home/alice/pub_git/frotz with --user-path=pub_git.
  52  */
  53 static const char *user_path;
  54
  55 /* Timeout, and initial timeout */
  56 static unsigned int timeout;
  57 static unsigned int init_timeout;
  58
  59 static char *hostname;
  60 static char *canon_hostname;
  61 static char *ip_address;
  62 static char *tcp_port;
  63
  64 static void logreport(int priority, const char *err, va_list params)
  65 {
  66         if (log_syslog) {
  67                 char buf[1024];
  68                 vsnprintf(buf, sizeof(buf), err, params);
  69                 syslog(priority, "%s", buf);
  70         } else {
  71                 /*
  72                  * Since stderr is set to buffered mode, the
  73                  * logging of different processes will not overlap
  74                  * unless they overflow the (rather big) buffers.
  75                  */
  76                 fprintf(stderr, "[%"PRIuMAX"] ", (uintmax_t)getpid());
  77                 vfprintf(stderr, err, params);
  78                 fputc('\n', stderr);
  79                 fflush(stderr);
  80         }
  81 }
  82
  83 __attribute__((format (printf, 1, 2)))
  84 static void logerror(const char *err, ...)
  85 {
  86         va_list params;
  87         va_start(params, err);
  88         logreport(LOG_ERR, err, params);
  89         va_end(params);
  90 }
  91
  92 __attribute__((format (printf, 1, 2)))
  93 static void loginfo(const char *err, ...)
  94 {
  95         va_list params;
  96         if (!verbose)
  97                 return;
  98         va_start(params, err);
  99         logreport(LOG_INFO, err, params);
 100         va_end(params);
 101 }
 102
 103 static void NORETURN daemon_die(const char *err, va_list params)
 104 {
 105         logreport(LOG_ERR, err, params);
 106         exit(1);
 107 }
 108
 109 static const char *path_ok(const char *directory)
 110 {
 111         static char rpath[PATH_MAX];
 112         static char interp_path[PATH_MAX];
 113         const char *path;
 114         const char *dir;
 115
 116         dir = directory;
 117
 118         if (daemon_avoid_alias(dir)) {
 119                 logerror("'%s': aliased", dir);
 120                 return NULL;
 121         }
 122
 123         if (*dir == '~') {
 124                 if (!user_path) {
 125                         logerror("'%s': User-path not allowed", dir);
 126                         return NULL;
 127                 }
 128                 if (*user_path) {
 129                         /* Got either "~alice" or "~alice/foo";
 130                          * rewrite them to "~alice/%s" or
 131                          * "~alice/%s/foo".
 132                          */
 133                         int namlen, restlen = strlen(dir);
 134                         const char *slash = strchr(dir, '/');
 135                         if (!slash)
 136                                 slash = dir + restlen;
 137                         namlen = slash - dir;
 138                         restlen -= namlen;
 139                         loginfo("userpath <%s>, request <%s>, namlen %d, restlen %d, slash <%s>", user_path, dir, namlen, restlen, slash);
 140                         snprintf(rpath, PATH_MAX, "%.*s/%s%.*s",
 141                                  namlen, dir, user_path, restlen, slash);
 142                         dir = rpath;
 143                 }
 144         }
 145         else if (interpolated_path && saw_extended_args) {
 146                 struct strbuf expanded_path = STRBUF_INIT;
 147                 struct strbuf_expand_dict_entry dict[6];
 148
 149                 dict[0].placeholder = "H"; dict[0].value = hostname;
 150                 dict[1].placeholder = "CH"; dict[1].value = canon_hostname;
 151                 dict[2].placeholder = "IP"; dict[2].value = ip_address;
 152                 dict[3].placeholder = "P"; dict[3].value = tcp_port;
 153                 dict[4].placeholder = "D"; dict[4].value = directory;
 154                 dict[5].placeholder = NULL; dict[5].value = NULL;
 155                 if (*dir != '/') {
 156                         /* Allow only absolute */
 157                         logerror("'%s': Non-absolute path denied (interpolated-path active)", dir);
 158                         return NULL;
 159                 }
 160
 161                 strbuf_expand(&expanded_path, interpolated_path,
 162                                 strbuf_expand_dict_cb, &dict);
 163                 strlcpy(interp_path, expanded_path.buf, PATH_MAX);
 164                 strbuf_release(&expanded_path);
 165                 loginfo("Interpolated dir '%s'", interp_path);
 166
 167                 dir = interp_path;
 168         }
 169         else if (base_path) {
 170                 if (*dir != '/') {
 171                         /* Allow only absolute */
 172                         logerror("'%s': Non-absolute path denied (base-path active)", dir);
 173                         return NULL;
 174                 }
 175                 snprintf(rpath, PATH_MAX, "%s%s", base_path, dir);
 176                 dir = rpath;
 177         }
 178
 179         path = enter_repo(dir, strict_paths);
 180         if (!path && base_path && base_path_relaxed) {
 181                 /*
 182                  * if we fail and base_path_relaxed is enabled, try without
 183                  * prefixing the base path
 184                  */
 185                 dir = directory;
 186                 path = enter_repo(dir, strict_paths);
 187         }
 188
 189         if (!path) {
 190                 logerror("'%s' does not appear to be a git repository", dir);
 191                 return NULL;
 192         }
 193
 194         if ( ok_paths && *ok_paths ) {
 195                 char **pp;
 196                 int pathlen = strlen(path);
 197
 198                 /* The validation is done on the paths after enter_repo
 199                  * appends optional {.git,.git/.git} and friends, but
 200                  * it does not use getcwd().  So if your /pub is
 201                  * a symlink to /mnt/pub, you can whitelist /pub and
 202                  * do not have to say /mnt/pub.
 203                  * Do not say /pub/.
 204                  */
 205                 for ( pp = ok_paths ; *pp ; pp++ ) {
 206                         int len = strlen(*pp);
 207                         if (len <= pathlen &&
 208                             !memcmp(*pp, path, len) &&
 209                             (path[len] == '\0' ||
 210                              (!strict_paths && path[len] == '/')))
 211                                 return path;
 212                 }
 213         }
 214         else {
 215                 /* be backwards compatible */
 216                 if (!strict_paths)
 217                         return path;
 218         }
 219
 220         logerror("'%s': not in whitelist", path);
 221         return NULL;            /* Fallthrough. Deny by default */
 222 }
 223
 224 typedef int (*daemon_service_fn)(void);
 225 struct daemon_service {
 226         const char *name;
 227         const char *config_name;
 228         daemon_service_fn fn;
 229         int enabled;
 230         int overridable;
 231 };
 232
 233 static struct daemon_service *service_looking_at;
 234 static int service_enabled;
 235
 236 static int git_daemon_config(const char *var, const char *value, void *cb)
 237 {
 238         const char *service;
 239
 240         if (skip_prefix(var, "daemon.", &service) &&
 241             !strcmp(service, service_looking_at->config_name)) {
 242                 service_enabled = git_config_bool(var, value);
 243                 return 0;
 244         }
 245
 246         /* we are not interested in parsing any other configuration here */
 247         return 0;
 248 }
 249
 250 static int daemon_error(const char *dir, const char *msg)
 251 {
 252         if (!informative_errors)
 253                 msg = "access denied or repository not exported";
 254         packet_write(1, "ERR %s: %s", msg, dir);
 255         return -1;
 256 }
 257
 258 static const char *access_hook;
 259
 260 static int run_access_hook(struct daemon_service *service, const char *dir, const char *path)
 261 {
 262         struct child_process child;
 263         struct strbuf buf = STRBUF_INIT;
 264         const char *argv[8];
 265         const char **arg = argv;
 266         char *eol;
 267         int seen_errors = 0;
 268
 269 #define STRARG(x) ((x) ? (x) : "")
 270         *arg++ = access_hook;
 271         *arg++ = service->name;
 272         *arg++ = path;
 273         *arg++ = STRARG(hostname);
 274         *arg++ = STRARG(canon_hostname);
 275         *arg++ = STRARG(ip_address);
 276         *arg++ = STRARG(tcp_port);
 277         *arg = NULL;
 278 #undef STRARG
 279
 280         memset(&child, 0, sizeof(child));
 281         child.use_shell = 1;
 282         child.argv = argv;
 283         child.no_stdin = 1;
 284         child.no_stderr = 1;
 285         child.out = -1;
 286         if (start_command(&child)) {
 287                 logerror("daemon access hook '%s' failed to start",
 288                          access_hook);
 289                 goto error_return;
 290         }
 291         if (strbuf_read(&buf, child.out, 0) < 0) {
 292                 logerror("failed to read from pipe to daemon access hook '%s'",
 293                          access_hook);
 294                 strbuf_reset(&buf);
 295                 seen_errors = 1;
 296         }
 297         if (close(child.out) < 0) {
 298                 logerror("failed to close pipe to daemon access hook '%s'",
 299                          access_hook);
 300                 seen_errors = 1;
 301         }
 302         if (finish_command(&child))
 303                 seen_errors = 1;
 304
 305         if (!seen_errors) {
 306                 strbuf_release(&buf);
 307                 return 0;
 308         }
 309
 310 error_return:
 311         strbuf_ltrim(&buf);
 312         if (!buf.len)
 313                 strbuf_addstr(&buf, "service rejected");
 314         eol = strchr(buf.buf, '\n');
 315         if (eol)
 316                 *eol = '\0';
 317         errno = EACCES;
 318         daemon_error(dir, buf.buf);
 319         strbuf_release(&buf);
 320         return -1;
 321 }
 322
 323 static int run_service(const char *dir, struct daemon_service *service)
 324 {
 325         const char *path;
 326         int enabled = service->enabled;
 327
 328         loginfo("Request %s for '%s'", service->name, dir);
 329
 330         if (!enabled && !service->overridable) {
 331                 logerror("'%s': service not enabled.", service->name);
 332                 errno = EACCES;
 333                 return daemon_error(dir, "service not enabled");
 334         }
 335
 336         if (!(path = path_ok(dir)))
 337                 return daemon_error(dir, "no such repository");
 338
 339         /*
 340          * Security on the cheap.
 341          *
 342          * We want a readable HEAD, usable "objects" directory, and
 343          * a "git-daemon-export-ok" flag that says that the other side
 344          * is ok with us doing this.
 345          *
 346          * path_ok() uses enter_repo() and does whitelist checking.
 347          * We only need to make sure the repository is exported.
 348          */
 349
 350         if (!export_all_trees && access("git-daemon-export-ok", F_OK)) {
 351                 logerror("'%s': repository not exported.", path);
 352                 errno = EACCES;
 353                 return daemon_error(dir, "repository not exported");
 354         }
 355
 356         if (service->overridable) {
 357                 service_looking_at = service;
 358                 service_enabled = -1;
 359                 git_config(git_daemon_config, NULL);
 360                 if (0 <= service_enabled)
 361                         enabled = service_enabled;
 362         }
 363         if (!enabled) {
 364                 logerror("'%s': service not enabled for '%s'",
 365                          service->name, path);
 366                 errno = EACCES;
 367                 return daemon_error(dir, "service not enabled");
 368         }
 369
 370         /*
 371          * Optionally, a hook can choose to deny access to the
 372          * repository depending on the phase of the moon.
 373          */
 374         if (access_hook && run_access_hook(service, dir, path))
 375                 return -1;
 376
 377         /*
 378          * We'll ignore SIGTERM from now on, we have a
 379          * good client.
 380          */
 381         signal(SIGTERM, SIG_IGN);
 382
 383         return service->fn();
 384 }
 385
 386 static void copy_to_log(int fd)
 387 {
 388         struct strbuf line = STRBUF_INIT;
 389         FILE *fp;
 390
 391         fp = fdopen(fd, "r");
 392         if (fp == NULL) {
 393                 logerror("fdopen of error channel failed");
 394                 close(fd);
 395                 return;
 396         }
 397
 398         while (strbuf_getline(&line, fp, '\n') != EOF) {
 399                 logerror("%s", line.buf);
 400                 strbuf_setlen(&line, 0);
 401         }
 402
 403         strbuf_release(&line);
 404         fclose(fp);
 405 }
 406
 407 static int run_service_command(const char **argv)
 408 {
 409         struct child_process cld;
 410
 411         memset(&cld, 0, sizeof(cld));
 412         cld.argv = argv;
 413         cld.git_cmd = 1;
 414         cld.err = -1;
 415         if (start_command(&cld))
 416                 return -1;
 417
 418         close(0);
 419         close(1);
 420
 421         copy_to_log(cld.err);
 422
 423         return finish_command(&cld);
 424 }
 425
 426 static int upload_pack(void)
 427 {
 428         /* Timeout as string */
 429         char timeout_buf[64];
 430         const char *argv[] = { "upload-pack", "--strict", NULL, ".", NULL };
 431
 432         argv[2] = timeout_buf;
 433
 434         snprintf(timeout_buf, sizeof timeout_buf, "--timeout=%u", timeout);
 435         return run_service_command(argv);
 436 }
 437
 438 static int upload_archive(void)
 439 {
 440         static const char *argv[] = { "upload-archive", ".", NULL };
 441         return run_service_command(argv);
 442 }
 443
 444 static int receive_pack(void)
 445 {
 446         static const char *argv[] = { "receive-pack", ".", NULL };
 447         return run_service_command(argv);
 448 }
 449
 450 static struct daemon_service daemon_service[] = {
 451         { "upload-archive", "uploadarch", upload_archive, 0, 1 },
 452         { "upload-pack", "uploadpack", upload_pack, 1, 1 },
 453         { "receive-pack", "receivepack", receive_pack, 0, 1 },
 454 };
 455
 456 static void enable_service(const char *name, int ena)
 457 {
 458         int i;
 459         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 460                 if (!strcmp(daemon_service[i].name, name)) {
 461                         daemon_service[i].enabled = ena;
 462                         return;
 463                 }
 464         }
 465         die("No such service %s", name);
 466 }
 467
 468 static void make_service_overridable(const char *name, int ena)
 469 {
 470         int i;
 471         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 472                 if (!strcmp(daemon_service[i].name, name)) {
 473                         daemon_service[i].overridable = ena;
 474                         return;
 475                 }
 476         }
 477         die("No such service %s", name);
 478 }
 479
 480 static void parse_host_and_port(char *hostport, char **host,
 481         char **port)
 482 {
 483         if (*hostport == '[') {
 484                 char *end;
 485
 486                 end = strchr(hostport, ']');
 487                 if (!end)
 488                         die("Invalid request ('[' without ']')");
 489                 *end = '\0';
 490                 *host = hostport + 1;
 491                 if (!end[1])
 492                         *port = NULL;
 493                 else if (end[1] == ':')
 494                         *port = end + 2;
 495                 else
 496                         die("Garbage after end of host part");
 497         } else {
 498                 *host = hostport;
 499                 *port = strrchr(hostport, ':');
 500                 if (*port) {
 501                         **port = '\0';
 502                         ++*port;
 503                 }
 504         }
 505 }
 506
 507 /*
 508  * Sanitize a string from the client so that it's OK to be inserted into a
 509  * filesystem path. Specifically, we disallow slashes, runs of "..", and
 510  * trailing and leading dots, which means that the client cannot escape
 511  * our base path via ".." traversal.
 512  */
 513 static void sanitize_client_strbuf(struct strbuf *out, const char *in)
 514 {
 515         for (; *in; in++) {
 516                 if (*in == '/')
 517                         continue;
 518                 if (*in == '.' && (!out->len || out->buf[out->len - 1] == '.'))
 519                         continue;
 520                 strbuf_addch(out, *in);
 521         }
 522
 523         while (out->len && out->buf[out->len - 1] == '.')
 524                 strbuf_setlen(out, out->len - 1);
 525 }
 526
 527 static char *sanitize_client(const char *in)
 528 {
 529         struct strbuf out = STRBUF_INIT;
 530         sanitize_client_strbuf(&out, in);
 531         return strbuf_detach(&out, NULL);
 532 }
 533
 534 /*
 535  * Like sanitize_client, but we also perform any canonicalization
 536  * to make life easier on the admin.
 537  */
 538 static char *canonicalize_client(const char *in)
 539 {
 540         struct strbuf out = STRBUF_INIT;
 541         sanitize_client_strbuf(&out, in);
 542         strbuf_tolower(&out);
 543         return strbuf_detach(&out, NULL);
 544 }
 545
 546 /*
 547  * Read the host as supplied by the client connection.
 548  */
 549 static void parse_host_arg(char *extra_args, int buflen)
 550 {
 551         char *val;
 552         int vallen;
 553         char *end = extra_args + buflen;
 554
 555         if (extra_args < end && *extra_args) {
 556                 saw_extended_args = 1;
 557                 if (strncasecmp("host=", extra_args, 5) == 0) {
 558                         val = extra_args + 5;
 559                         vallen = strlen(val) + 1;
 560                         if (*val) {
 561                                 /* Split <host>:<port> at colon. */
 562                                 char *host;
 563                                 char *port;
 564                                 parse_host_and_port(val, &host, &port);
 565                                 if (port) {
 566                                         free(tcp_port);
 567                                         tcp_port = sanitize_client(port);
 568                                 }
 569                                 free(hostname);
 570                                 hostname = canonicalize_client(host);
 571                         }
 572
 573                         /* On to the next one */
 574                         extra_args = val + vallen;
 575                 }
 576                 if (extra_args < end && *extra_args)
 577                         die("Invalid request");
 578         }
 579
 580         /*
 581          * Locate canonical hostname and its IP address.
 582          */
 583         if (hostname) {
 584 #ifndef NO_IPV6
 585                 struct addrinfo hints;
 586                 struct addrinfo *ai;
 587                 int gai;
 588                 static char addrbuf[HOST_NAME_MAX + 1];
 589
 590                 memset(&hints, 0, sizeof(hints));
 591                 hints.ai_flags = AI_CANONNAME;
 592
 593                 gai = getaddrinfo(hostname, NULL, &hints, &ai);
 594                 if (!gai) {
 595                         struct sockaddr_in *sin_addr = (void *)ai->ai_addr;
 596
 597                         inet_ntop(AF_INET, &sin_addr->sin_addr,
 598                                   addrbuf, sizeof(addrbuf));
 599                         free(ip_address);
 600                         ip_address = xstrdup(addrbuf);
 601
 602                         free(canon_hostname);
 603                         canon_hostname = ai->ai_canonname ?
 604                                 sanitize_client(ai->ai_canonname) :
 605                                 xstrdup(ip_address);
 606
 607                         freeaddrinfo(ai);
 608                 }
 609 #else
 610                 struct hostent *hent;
 611                 struct sockaddr_in sa;
 612                 char **ap;
 613                 static char addrbuf[HOST_NAME_MAX + 1];
 614
 615                 hent = gethostbyname(hostname);
 616                 if (hent) {
 617                         ap = hent->h_addr_list;
 618                         memset(&sa, 0, sizeof sa);
 619                         sa.sin_family = hent->h_addrtype;
 620                         sa.sin_port = htons(0);
 621                         memcpy(&sa.sin_addr, *ap, hent->h_length);
 622
 623                         inet_ntop(hent->h_addrtype, &sa.sin_addr,
 624                                   addrbuf, sizeof(addrbuf));
 625
 626                         free(canon_hostname);
 627                         canon_hostname = sanitize_client(hent->h_name);
 628                         free(ip_address);
 629                         ip_address = xstrdup(addrbuf);
 630                 }
 631 #endif
 632         }
 633 }
 634
 635
 636 static int execute(void)
 637 {
 638         char *line = packet_buffer;
 639         int pktlen, len, i;
 640         char *addr = getenv("REMOTE_ADDR"), *port = getenv("REMOTE_PORT");
 641
 642         if (addr)
 643                 loginfo("Connection from %s:%s", addr, port);
 644
 645         alarm(init_timeout ? init_timeout : timeout);
 646         pktlen = packet_read(0, NULL, NULL, packet_buffer, sizeof(packet_buffer), 0);
 647         alarm(0);
 648
 649         len = strlen(line);
 650         if (pktlen != len)
 651                 loginfo("Extended attributes (%d bytes) exist <%.*s>",
 652                         (int) pktlen - len,
 653                         (int) pktlen - len, line + len + 1);
 654         if (len && line[len-1] == '\n') {
 655                 line[--len] = 0;
 656                 pktlen--;
 657         }
 658
 659         free(hostname);
 660         free(canon_hostname);
 661         free(ip_address);
 662         free(tcp_port);
 663         hostname = canon_hostname = ip_address = tcp_port = NULL;
 664
 665         if (len != pktlen)
 666                 parse_host_arg(line + len + 1, pktlen - len - 1);
 667
 668         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 669                 struct daemon_service *s = &(daemon_service[i]);
 670                 const char *arg;
 671
 672                 if (skip_prefix(line, "git-", &arg) &&
 673                     skip_prefix(arg, s->name, &arg) &&
 674                     *arg++ == ' ') {
 675                         /*
 676                          * Note: The directory here is probably context sensitive,
 677                          * and might depend on the actual service being performed.
 678                          */
 679                         return run_service(arg, s);
 680                 }
 681         }
 682
 683         logerror("Protocol error: '%s'", line);
 684         return -1;
 685 }
 686
 687 static int addrcmp(const struct sockaddr_storage *s1,
 688     const struct sockaddr_storage *s2)
 689 {
 690         const struct sockaddr *sa1 = (const struct sockaddr*) s1;
 691         const struct sockaddr *sa2 = (const struct sockaddr*) s2;
 692
 693         if (sa1->sa_family != sa2->sa_family)
 694                 return sa1->sa_family - sa2->sa_family;
 695         if (sa1->sa_family == AF_INET)
 696                 return memcmp(&((struct sockaddr_in *)s1)->sin_addr,
 697                     &((struct sockaddr_in *)s2)->sin_addr,
 698                     sizeof(struct in_addr));
 699 #ifndef NO_IPV6
 700         if (sa1->sa_family == AF_INET6)
 701                 return memcmp(&((struct sockaddr_in6 *)s1)->sin6_addr,
 702                     &((struct sockaddr_in6 *)s2)->sin6_addr,
 703                     sizeof(struct in6_addr));
 704 #endif
 705         return 0;
 706 }
 707
 708 static int max_connections = 32;
 709
 710 static unsigned int live_children;
 711
 712 static struct child {
 713         struct child *next;
 714         struct child_process cld;
 715         struct sockaddr_storage address;
 716 } *firstborn;
 717
 718 static void add_child(struct child_process *cld, struct sockaddr *addr, socklen_t addrlen)
 719 {
 720         struct child *newborn, **cradle;
 721
 722         newborn = xcalloc(1, sizeof(*newborn));
 723         live_children++;
 724         memcpy(&newborn->cld, cld, sizeof(*cld));
 725         memcpy(&newborn->address, addr, addrlen);
 726         for (cradle = &firstborn; *cradle; cradle = &(*cradle)->next)
 727                 if (!addrcmp(&(*cradle)->address, &newborn->address))
 728                         break;
 729         newborn->next = *cradle;
 730         *cradle = newborn;
 731 }
 732
 733 /*
 734  * This gets called if the number of connections grows
 735  * past "max_connections".
 736  *
 737  * We kill the newest connection from a duplicate IP.
 738  */
 739 static void kill_some_child(void)
 740 {
 741         const struct child *blanket, *next;
 742
 743         if (!(blanket = firstborn))
 744                 return;
 745
 746         for (; (next = blanket->next); blanket = next)
 747                 if (!addrcmp(&blanket->address, &next->address)) {
 748                         kill(blanket->cld.pid, SIGTERM);
 749                         break;
 750                 }
 751 }
 752
 753 static void check_dead_children(void)
 754 {
 755         int status;
 756         pid_t pid;
 757
 758         struct child **cradle, *blanket;
 759         for (cradle = &firstborn; (blanket = *cradle);)
 760                 if ((pid = waitpid(blanket->cld.pid, &status, WNOHANG)) > 1) {
 761                         const char *dead = "";
 762                         if (status)
 763                                 dead = " (with error)";
 764                         loginfo("[%"PRIuMAX"] Disconnected%s", (uintmax_t)pid, dead);
 765
 766                         /* remove the child */
 767                         *cradle = blanket->next;
 768                         live_children--;
 769                         free(blanket);
 770                 } else
 771                         cradle = &blanket->next;
 772 }
 773
 774 static char **cld_argv;
 775 static void handle(int incoming, struct sockaddr *addr, socklen_t addrlen)
 776 {
 777         struct child_process cld = { NULL };
 778         char addrbuf[300] = "REMOTE_ADDR=", portbuf[300];
 779         char *env[] = { addrbuf, portbuf, NULL };
 780
 781         if (max_connections && live_children >= max_connections) {
 782                 kill_some_child();
 783                 sleep(1);  /* give it some time to die */
 784                 check_dead_children();
 785                 if (live_children >= max_connections) {
 786                         close(incoming);
 787                         logerror("Too many children, dropping connection");
 788                         return;
 789                 }
 790         }
 791
 792         if (addr->sa_family == AF_INET) {
 793                 struct sockaddr_in *sin_addr = (void *) addr;
 794                 inet_ntop(addr->sa_family, &sin_addr->sin_addr, addrbuf + 12,
 795                     sizeof(addrbuf) - 12);
 796                 snprintf(portbuf, sizeof(portbuf), "REMOTE_PORT=%d",
 797                     ntohs(sin_addr->sin_port));
 798 #ifndef NO_IPV6
 799         } else if (addr->sa_family == AF_INET6) {
 800                 struct sockaddr_in6 *sin6_addr = (void *) addr;
 801
 802                 char *buf = addrbuf + 12;
 803                 *buf++ = '['; *buf = '\0'; /* stpcpy() is cool */
 804                 inet_ntop(AF_INET6, &sin6_addr->sin6_addr, buf,
 805                     sizeof(addrbuf) - 13);
 806                 strcat(buf, "]");
 807
 808                 snprintf(portbuf, sizeof(portbuf), "REMOTE_PORT=%d",
 809                     ntohs(sin6_addr->sin6_port));
 810 #endif
 811         }
 812
 813         cld.env = (const char **)env;
 814         cld.argv = (const char **)cld_argv;
 815         cld.in = incoming;
 816         cld.out = dup(incoming);
 817
 818         if (start_command(&cld))
 819                 logerror("unable to fork");
 820         else
 821                 add_child(&cld, addr, addrlen);
 822 }
 823
 824 static void child_handler(int signo)
 825 {
 826         /*
 827          * Otherwise empty handler because systemcalls will get interrupted
 828          * upon signal receipt
 829          * SysV needs the handler to be rearmed
 830          */
 831         signal(SIGCHLD, child_handler);
 832 }
 833
 834 static int set_reuse_addr(int sockfd)
 835 {
 836         int on = 1;
 837
 838         if (!reuseaddr)
 839                 return 0;
 840         return setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
 841                           &on, sizeof(on));
 842 }
 843
 844 struct socketlist {
 845         int *list;
 846         size_t nr;
 847         size_t alloc;
 848 };
 849
 850 static const char *ip2str(int family, struct sockaddr *sin, socklen_t len)
 851 {
 852 #ifdef NO_IPV6
 853         static char ip[INET_ADDRSTRLEN];
 854 #else
 855         static char ip[INET6_ADDRSTRLEN];
 856 #endif
 857
 858         switch (family) {
 859 #ifndef NO_IPV6
 860         case AF_INET6:
 861                 inet_ntop(family, &((struct sockaddr_in6*)sin)->sin6_addr, ip, len);
 862                 break;
 863 #endif
 864         case AF_INET:
 865                 inet_ntop(family, &((struct sockaddr_in*)sin)->sin_addr, ip, len);
 866                 break;
 867         default:
 868                 strcpy(ip, "<unknown>");
 869         }
 870         return ip;
 871 }
 872
 873 #ifndef NO_IPV6
 874
 875 static int setup_named_sock(char *listen_addr, int listen_port, struct socketlist *socklist)
 876 {
 877         int socknum = 0;
 878         char pbuf[NI_MAXSERV];
 879         struct addrinfo hints, *ai0, *ai;
 880         int gai;
 881         long flags;
 882
 883         sprintf(pbuf, "%d", listen_port);
 884         memset(&hints, 0, sizeof(hints));
 885         hints.ai_family = AF_UNSPEC;
 886         hints.ai_socktype = SOCK_STREAM;
 887         hints.ai_protocol = IPPROTO_TCP;
 888         hints.ai_flags = AI_PASSIVE;
 889
 890         gai = getaddrinfo(listen_addr, pbuf, &hints, &ai0);
 891         if (gai) {
 892                 logerror("getaddrinfo() for %s failed: %s", listen_addr, gai_strerror(gai));
 893                 return 0;
 894         }
 895
 896         for (ai = ai0; ai; ai = ai->ai_next) {
 897                 int sockfd;
 898
 899                 sockfd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
 900                 if (sockfd < 0)
 901                         continue;
 902                 if (sockfd >= FD_SETSIZE) {
 903                         logerror("Socket descriptor too large");
 904                         close(sockfd);
 905                         continue;
 906                 }
 907
 908 #ifdef IPV6_V6ONLY
 909                 if (ai->ai_family == AF_INET6) {
 910                         int on = 1;
 911                         setsockopt(sockfd, IPPROTO_IPV6, IPV6_V6ONLY,
 912                                    &on, sizeof(on));
 913                         /* Note: error is not fatal */
 914                 }
 915 #endif
 916
 917                 if (set_reuse_addr(sockfd)) {
 918                         logerror("Could not set SO_REUSEADDR: %s", strerror(errno));
 919                         close(sockfd);
 920                         continue;
 921                 }
 922
 923                 if (bind(sockfd, ai->ai_addr, ai->ai_addrlen) < 0) {
 924                         logerror("Could not bind to %s: %s",
 925                                  ip2str(ai->ai_family, ai->ai_addr, ai->ai_addrlen),
 926                                  strerror(errno));
 927                         close(sockfd);
 928                         continue;       /* not fatal */
 929                 }
 930                 if (listen(sockfd, 5) < 0) {
 931                         logerror("Could not listen to %s: %s",
 932                                  ip2str(ai->ai_family, ai->ai_addr, ai->ai_addrlen),
 933                                  strerror(errno));
 934                         close(sockfd);
 935                         continue;       /* not fatal */
 936                 }
 937
 938                 flags = fcntl(sockfd, F_GETFD, 0);
 939                 if (flags >= 0)
 940                         fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
 941
 942                 ALLOC_GROW(socklist->list, socklist->nr + 1, socklist->alloc);
 943                 socklist->list[socklist->nr++] = sockfd;
 944                 socknum++;
 945         }
 946
 947         freeaddrinfo(ai0);
 948
 949         return socknum;
 950 }
 951
 952 #else /* NO_IPV6 */
 953
 954 static int setup_named_sock(char *listen_addr, int listen_port, struct socketlist *socklist)
 955 {
 956         struct sockaddr_in sin;
 957         int sockfd;
 958         long flags;
 959
 960         memset(&sin, 0, sizeof sin);
 961         sin.sin_family = AF_INET;
 962         sin.sin_port = htons(listen_port);
 963
 964         if (listen_addr) {
 965                 /* Well, host better be an IP address here. */
 966                 if (inet_pton(AF_INET, listen_addr, &sin.sin_addr.s_addr) <= 0)
 967                         return 0;
 968         } else {
 969                 sin.sin_addr.s_addr = htonl(INADDR_ANY);
 970         }
 971
 972         sockfd = socket(AF_INET, SOCK_STREAM, 0);
 973         if (sockfd < 0)
 974                 return 0;
 975
 976         if (set_reuse_addr(sockfd)) {
 977                 logerror("Could not set SO_REUSEADDR: %s", strerror(errno));
 978                 close(sockfd);
 979                 return 0;
 980         }
 981
 982         if ( bind(sockfd, (struct sockaddr *)&sin, sizeof sin) < 0 ) {
 983                 logerror("Could not bind to %s: %s",
 984                          ip2str(AF_INET, (struct sockaddr *)&sin, sizeof(sin)),
 985                          strerror(errno));
 986                 close(sockfd);
 987                 return 0;
 988         }
 989
 990         if (listen(sockfd, 5) < 0) {
 991                 logerror("Could not listen to %s: %s",
 992                          ip2str(AF_INET, (struct sockaddr *)&sin, sizeof(sin)),
 993                          strerror(errno));
 994                 close(sockfd);
 995                 return 0;
 996         }
 997
 998         flags = fcntl(sockfd, F_GETFD, 0);
 999         if (flags >= 0)
1000                 fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
1001
1002         ALLOC_GROW(socklist->list, socklist->nr + 1, socklist->alloc);
1003         socklist->list[socklist->nr++] = sockfd;
1004         return 1;
1005 }
1006
1007 #endif
1008
1009 static void socksetup(struct string_list *listen_addr, int listen_port, struct socketlist *socklist)
1010 {
1011         if (!listen_addr->nr)
1012                 setup_named_sock(NULL, listen_port, socklist);
1013         else {
1014                 int i, socknum;
1015                 for (i = 0; i < listen_addr->nr; i++) {
1016                         socknum = setup_named_sock(listen_addr->items[i].string,
1017                                                    listen_port, socklist);
1018
1019                         if (socknum == 0)
1020                                 logerror("unable to allocate any listen sockets for host %s on port %u",
1021                                          listen_addr->items[i].string, listen_port);
1022                 }
1023         }
1024 }
1025
1026 static int service_loop(struct socketlist *socklist)
1027 {
1028         struct pollfd *pfd;
1029         int i;
1030
1031         pfd = xcalloc(socklist->nr, sizeof(struct pollfd));
1032
1033         for (i = 0; i < socklist->nr; i++) {
1034                 pfd[i].fd = socklist->list[i];
1035                 pfd[i].events = POLLIN;
1036         }
1037
1038         signal(SIGCHLD, child_handler);
1039
1040         for (;;) {
1041                 int i;
1042
1043                 check_dead_children();
1044
1045                 if (poll(pfd, socklist->nr, -1) < 0) {
1046                         if (errno != EINTR) {
1047                                 logerror("Poll failed, resuming: %s",
1048                                       strerror(errno));
1049                                 sleep(1);
1050                         }
1051                         continue;
1052                 }
1053
1054                 for (i = 0; i < socklist->nr; i++) {
1055                         if (pfd[i].revents & POLLIN) {
1056                                 union {
1057                                         struct sockaddr sa;
1058                                         struct sockaddr_in sai;
1059 #ifndef NO_IPV6
1060                                         struct sockaddr_in6 sai6;
1061 #endif
1062                                 } ss;
1063                                 socklen_t sslen = sizeof(ss);
1064                                 int incoming = accept(pfd[i].fd, &ss.sa, &sslen);
1065                                 if (incoming < 0) {
1066                                         switch (errno) {
1067                                         case EAGAIN:
1068                                         case EINTR:
1069                                         case ECONNABORTED:
1070                                                 continue;
1071                                         default:
1072                                                 die_errno("accept returned");
1073                                         }
1074                                 }
1075                                 handle(incoming, &ss.sa, sslen);
1076                         }
1077                 }
1078         }
1079 }
1080
1081 #ifdef NO_POSIX_GOODIES
1082
1083 struct credentials;
1084
1085 static void drop_privileges(struct credentials *cred)
1086 {
1087         /* nothing */
1088 }
1089
1090 static struct credentials *prepare_credentials(const char *user_name,
1091     const char *group_name)
1092 {
1093         die("--user not supported on this platform");
1094 }
1095
1096 #else
1097
1098 struct credentials {
1099         struct passwd *pass;
1100         gid_t gid;
1101 };
1102
1103 static void drop_privileges(struct credentials *cred)
1104 {
1105         if (cred && (initgroups(cred->pass->pw_name, cred->gid) ||
1106             setgid (cred->gid) || setuid(cred->pass->pw_uid)))
1107                 die("cannot drop privileges");
1108 }
1109
1110 static struct credentials *prepare_credentials(const char *user_name,
1111     const char *group_name)
1112 {
1113         static struct credentials c;
1114
1115         c.pass = getpwnam(user_name);
1116         if (!c.pass)
1117                 die("user not found - %s", user_name);
1118
1119         if (!group_name)
1120                 c.gid = c.pass->pw_gid;
1121         else {
1122                 struct group *group = getgrnam(group_name);
1123                 if (!group)
1124                         die("group not found - %s", group_name);
1125
1126                 c.gid = group->gr_gid;
1127         }
1128
1129         return &c;
1130 }
1131 #endif
1132
1133 static void store_pid(const char *path)
1134 {
1135         FILE *f = fopen(path, "w");
1136         if (!f)
1137                 die_errno("cannot open pid file '%s'", path);
1138         if (fprintf(f, "%"PRIuMAX"\n", (uintmax_t) getpid()) < 0 || fclose(f) != 0)
1139                 die_errno("failed to write pid file '%s'", path);
1140 }
1141
1142 static int serve(struct string_list *listen_addr, int listen_port,
1143     struct credentials *cred)
1144 {
1145         struct socketlist socklist = { NULL, 0, 0 };
1146
1147         socksetup(listen_addr, listen_port, &socklist);
1148         if (socklist.nr == 0)
1149                 die("unable to allocate any listen sockets on port %u",
1150                     listen_port);
1151
1152         drop_privileges(cred);
1153
1154         loginfo("Ready to rumble");
1155
1156         return service_loop(&socklist);
1157 }
1158
1159 int main(int argc, char **argv)
1160 {
1161         int listen_port = 0;
1162         struct string_list listen_addr = STRING_LIST_INIT_NODUP;
1163         int serve_mode = 0, inetd_mode = 0;
1164         const char *pid_file = NULL, *user_name = NULL, *group_name = NULL;
1165         int detach = 0;
1166         struct credentials *cred = NULL;
1167         int i;
1168
1169         git_setup_gettext();
1170
1171         git_extract_argv0_path(argv[0]);
1172
1173         for (i = 1; i < argc; i++) {
1174                 char *arg = argv[i];
1175                 const char *v;
1176
1177                 if (skip_prefix(arg, "--listen=", &v)) {
1178                         string_list_append(&listen_addr, xstrdup_tolower(v));
1179                         continue;
1180                 }
1181                 if (skip_prefix(arg, "--port=", &v)) {
1182                         char *end;
1183                         unsigned long n;
1184                         n = strtoul(v, &end, 0);
1185                         if (*v && !*end) {
1186                                 listen_port = n;
1187                                 continue;
1188                         }
1189                 }
1190                 if (!strcmp(arg, "--serve")) {
1191                         serve_mode = 1;
1192                         continue;
1193                 }
1194                 if (!strcmp(arg, "--inetd")) {
1195                         inetd_mode = 1;
1196                         log_syslog = 1;
1197                         continue;
1198                 }
1199                 if (!strcmp(arg, "--verbose")) {
1200                         verbose = 1;
1201                         continue;
1202                 }
1203                 if (!strcmp(arg, "--syslog")) {
1204                         log_syslog = 1;
1205                         continue;
1206                 }
1207                 if (!strcmp(arg, "--export-all")) {
1208                         export_all_trees = 1;
1209                         continue;
1210                 }
1211                 if (skip_prefix(arg, "--access-hook=", &v)) {
1212                         access_hook = v;
1213                         continue;
1214                 }
1215                 if (skip_prefix(arg, "--timeout=", &v)) {
1216                         timeout = atoi(v);
1217                         continue;
1218                 }
1219                 if (skip_prefix(arg, "--init-timeout=", &v)) {
1220                         init_timeout = atoi(v);
1221                         continue;
1222                 }
1223                 if (skip_prefix(arg, "--max-connections=", &v)) {
1224                         max_connections = atoi(v);
1225                         if (max_connections < 0)
1226                                 max_connections = 0;            /* unlimited */
1227                         continue;
1228                 }
1229                 if (!strcmp(arg, "--strict-paths")) {
1230                         strict_paths = 1;
1231                         continue;
1232                 }
1233                 if (skip_prefix(arg, "--base-path=", &v)) {
1234                         base_path = v;
1235                         continue;
1236                 }
1237                 if (!strcmp(arg, "--base-path-relaxed")) {
1238                         base_path_relaxed = 1;
1239                         continue;
1240                 }
1241                 if (skip_prefix(arg, "--interpolated-path=", &v)) {
1242                         interpolated_path = v;
1243                         continue;
1244                 }
1245                 if (!strcmp(arg, "--reuseaddr")) {
1246                         reuseaddr = 1;
1247                         continue;
1248                 }
1249                 if (!strcmp(arg, "--user-path")) {
1250                         user_path = "";
1251                         continue;
1252                 }
1253                 if (skip_prefix(arg, "--user-path=", &v)) {
1254                         user_path = v;
1255                         continue;
1256                 }
1257                 if (skip_prefix(arg, "--pid-file=", &v)) {
1258                         pid_file = v;
1259                         continue;
1260                 }
1261                 if (!strcmp(arg, "--detach")) {
1262                         detach = 1;
1263                         log_syslog = 1;
1264                         continue;
1265                 }
1266                 if (skip_prefix(arg, "--user=", &v)) {
1267                         user_name = v;
1268                         continue;
1269                 }
1270                 if (skip_prefix(arg, "--group=", &v)) {
1271                         group_name = v;
1272                         continue;
1273                 }
1274                 if (skip_prefix(arg, "--enable=", &v)) {
1275                         enable_service(v, 1);
1276                         continue;
1277                 }
1278                 if (skip_prefix(arg, "--disable=", &v)) {
1279                         enable_service(v, 0);
1280                         continue;
1281                 }
1282                 if (skip_prefix(arg, "--allow-override=", &v)) {
1283                         make_service_overridable(v, 1);
1284                         continue;
1285                 }
1286                 if (skip_prefix(arg, "--forbid-override=", &v)) {
1287                         make_service_overridable(v, 0);
1288                         continue;
1289                 }
1290                 if (!strcmp(arg, "--informative-errors")) {
1291                         informative_errors = 1;
1292                         continue;
1293                 }
1294                 if (!strcmp(arg, "--no-informative-errors")) {
1295                         informative_errors = 0;
1296                         continue;
1297                 }
1298                 if (!strcmp(arg, "--")) {
1299                         ok_paths = &argv[i+1];
1300                         break;
1301                 } else if (arg[0] != '-') {
1302                         ok_paths = &argv[i];
1303                         break;
1304                 }
1305
1306                 usage(daemon_usage);
1307         }
1308
1309         if (log_syslog) {
1310                 openlog("git-daemon", LOG_PID, LOG_DAEMON);
1311                 set_die_routine(daemon_die);
1312         } else
1313                 /* avoid splitting a message in the middle */
1314                 setvbuf(stderr, NULL, _IOFBF, 4096);
1315
1316         if (inetd_mode && (detach || group_name || user_name))
1317                 die("--detach, --user and --group are incompatible with --inetd");
1318
1319         if (inetd_mode && (listen_port || (listen_addr.nr > 0)))
1320                 die("--listen= and --port= are incompatible with --inetd");
1321         else if (listen_port == 0)
1322                 listen_port = DEFAULT_GIT_PORT;
1323
1324         if (group_name && !user_name)
1325                 die("--group supplied without --user");
1326
1327         if (user_name)
1328                 cred = prepare_credentials(user_name, group_name);
1329
1330         if (strict_paths && (!ok_paths || !*ok_paths))
1331                 die("option --strict-paths requires a whitelist");
1332
1333         if (base_path && !is_directory(base_path))
1334                 die("base-path '%s' does not exist or is not a directory",
1335                     base_path);
1336
1337         if (inetd_mode) {
1338                 if (!freopen("/dev/null", "w", stderr))
1339                         die_errno("failed to redirect stderr to /dev/null");
1340         }
1341
1342         if (inetd_mode || serve_mode)
1343                 return execute();
1344
1345         if (detach) {
1346                 if (daemonize())
1347                         die("--detach not supported on this platform");
1348         } else
1349                 sanitize_stdfds();
1350
1351         if (pid_file)
1352                 store_pid(pid_file);
1353
1354         /* prepare argv for serving-processes */
1355         cld_argv = xmalloc(sizeof (char *) * (argc + 2));
1356         cld_argv[0] = argv[0];  /* git-daemon */
1357         cld_argv[1] = "--serve";
1358         for (i = 1; i < argc; ++i)
1359                 cld_argv[i+1] = argv[i];
1360         cld_argv[argc+1] = NULL;
1361
1362         return serve(&listen_addr, listen_port, cred);
1363 }