git.oblomov.eu Git - git/blob - 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 #ifndef HOST_NAME_MAX
   8 #define HOST_NAME_MAX 256
   9 #endif
  10
  11 #ifdef NO_INITGROUPS
  12 #define initgroups(x, y) (0) /* nothing */
  13 #endif
  14
  15 static int log_syslog;
  16 static int verbose;
  17 static int reuseaddr;
  18 static int informative_errors;
  19
  20 static const char daemon_usage[] =
  21 "git daemon [--verbose] [--syslog] [--export-all]\n"
  22 "           [--timeout=<n>] [--init-timeout=<n>] [--max-connections=<n>]\n"
  23 "           [--strict-paths] [--base-path=<path>] [--base-path-relaxed]\n"
  24 "           [--user-path | --user-path=<path>]\n"
  25 "           [--interpolated-path=<path>]\n"
  26 "           [--reuseaddr] [--pid-file=<file>]\n"
  27 "           [--(enable|disable|allow-override|forbid-override)=<service>]\n"
  28 "           [--access-hook=<path>]\n"
  29 "           [--inetd | [--listen=<host_or_ipaddr>] [--port=<n>]\n"
  30 "                      [--detach] [--user=<user> [--group=<group>]]\n"
  31 "           [<directory>...]";
  32
  33 /* List of acceptable pathname prefixes */
  34 static const char **ok_paths;
  35 static int strict_paths;
  36
  37 /* If this is set, git-daemon-export-ok is not required */
  38 static int export_all_trees;
  39
  40 /* Take all paths relative to this one if non-NULL */
  41 static const char *base_path;
  42 static const char *interpolated_path;
  43 static int base_path_relaxed;
  44
  45 /* If defined, ~user notation is allowed and the string is inserted
  46  * after ~user/.  E.g. a request to git://host/~alice/frotz would
  47  * go to /home/alice/pub_git/frotz with --user-path=pub_git.
  48  */
  49 static const char *user_path;
  50
  51 /* Timeout, and initial timeout */
  52 static unsigned int timeout;
  53 static unsigned int init_timeout;
  54
  55 struct hostinfo {
  56         struct strbuf hostname;
  57         struct strbuf canon_hostname;
  58         struct strbuf ip_address;
  59         struct strbuf tcp_port;
  60         unsigned int hostname_lookup_done:1;
  61         unsigned int saw_extended_args:1;
  62 };
  63
  64 static void lookup_hostname(struct hostinfo *hi);
  65
  66 static const char *get_canon_hostname(struct hostinfo *hi)
  67 {
  68         lookup_hostname(hi);
  69         return hi->canon_hostname.buf;
  70 }
  71
  72 static const char *get_ip_address(struct hostinfo *hi)
  73 {
  74         lookup_hostname(hi);
  75         return hi->ip_address.buf;
  76 }
  77
  78 static void logreport(int priority, const char *err, va_list params)
  79 {
  80         if (log_syslog) {
  81                 char buf[1024];
  82                 vsnprintf(buf, sizeof(buf), err, params);
  83                 syslog(priority, "%s", buf);
  84         } else {
  85                 /*
  86                  * Since stderr is set to buffered mode, the
  87                  * logging of different processes will not overlap
  88                  * unless they overflow the (rather big) buffers.
  89                  */
  90                 fprintf(stderr, "[%"PRIuMAX"] ", (uintmax_t)getpid());
  91                 vfprintf(stderr, err, params);
  92                 fputc('\n', stderr);
  93                 fflush(stderr);
  94         }
  95 }
  96
  97 __attribute__((format (printf, 1, 2)))
  98 static void logerror(const char *err, ...)
  99 {
 100         va_list params;
 101         va_start(params, err);
 102         logreport(LOG_ERR, err, params);
 103         va_end(params);
 104 }
 105
 106 __attribute__((format (printf, 1, 2)))
 107 static void loginfo(const char *err, ...)
 108 {
 109         va_list params;
 110         if (!verbose)
 111                 return;
 112         va_start(params, err);
 113         logreport(LOG_INFO, err, params);
 114         va_end(params);
 115 }
 116
 117 static void NORETURN daemon_die(const char *err, va_list params)
 118 {
 119         logreport(LOG_ERR, err, params);
 120         exit(1);
 121 }
 122
 123 struct expand_path_context {
 124         const char *directory;
 125         struct hostinfo *hostinfo;
 126 };
 127
 128 static size_t expand_path(struct strbuf *sb, const char *placeholder, void *ctx)
 129 {
 130         struct expand_path_context *context = ctx;
 131         struct hostinfo *hi = context->hostinfo;
 132
 133         switch (placeholder[0]) {
 134         case 'H':
 135                 strbuf_addbuf(sb, &hi->hostname);
 136                 return 1;
 137         case 'C':
 138                 if (placeholder[1] == 'H') {
 139                         strbuf_addstr(sb, get_canon_hostname(hi));
 140                         return 2;
 141                 }
 142                 break;
 143         case 'I':
 144                 if (placeholder[1] == 'P') {
 145                         strbuf_addstr(sb, get_ip_address(hi));
 146                         return 2;
 147                 }
 148                 break;
 149         case 'P':
 150                 strbuf_addbuf(sb, &hi->tcp_port);
 151                 return 1;
 152         case 'D':
 153                 strbuf_addstr(sb, context->directory);
 154                 return 1;
 155         }
 156         return 0;
 157 }
 158
 159 static const char *path_ok(const char *directory, struct hostinfo *hi)
 160 {
 161         static char rpath[PATH_MAX];
 162         static char interp_path[PATH_MAX];
 163         const char *path;
 164         const char *dir;
 165
 166         dir = directory;
 167
 168         if (daemon_avoid_alias(dir)) {
 169                 logerror("'%s': aliased", dir);
 170                 return NULL;
 171         }
 172
 173         if (*dir == '~') {
 174                 if (!user_path) {
 175                         logerror("'%s': User-path not allowed", dir);
 176                         return NULL;
 177                 }
 178                 if (*user_path) {
 179                         /* Got either "~alice" or "~alice/foo";
 180                          * rewrite them to "~alice/%s" or
 181                          * "~alice/%s/foo".
 182                          */
 183                         int namlen, restlen = strlen(dir);
 184                         const char *slash = strchr(dir, '/');
 185                         if (!slash)
 186                                 slash = dir + restlen;
 187                         namlen = slash - dir;
 188                         restlen -= namlen;
 189                         loginfo("userpath <%s>, request <%s>, namlen %d, restlen %d, slash <%s>", user_path, dir, namlen, restlen, slash);
 190                         snprintf(rpath, PATH_MAX, "%.*s/%s%.*s",
 191                                  namlen, dir, user_path, restlen, slash);
 192                         dir = rpath;
 193                 }
 194         }
 195         else if (interpolated_path && hi->saw_extended_args) {
 196                 struct strbuf expanded_path = STRBUF_INIT;
 197                 struct expand_path_context context;
 198
 199                 context.directory = directory;
 200                 context.hostinfo = hi;
 201
 202                 if (*dir != '/') {
 203                         /* Allow only absolute */
 204                         logerror("'%s': Non-absolute path denied (interpolated-path active)", dir);
 205                         return NULL;
 206                 }
 207
 208                 strbuf_expand(&expanded_path, interpolated_path,
 209                               expand_path, &context);
 210                 strlcpy(interp_path, expanded_path.buf, PATH_MAX);
 211                 strbuf_release(&expanded_path);
 212                 loginfo("Interpolated dir '%s'", interp_path);
 213
 214                 dir = interp_path;
 215         }
 216         else if (base_path) {
 217                 if (*dir != '/') {
 218                         /* Allow only absolute */
 219                         logerror("'%s': Non-absolute path denied (base-path active)", dir);
 220                         return NULL;
 221                 }
 222                 snprintf(rpath, PATH_MAX, "%s%s", base_path, dir);
 223                 dir = rpath;
 224         }
 225
 226         path = enter_repo(dir, strict_paths);
 227         if (!path && base_path && base_path_relaxed) {
 228                 /*
 229                  * if we fail and base_path_relaxed is enabled, try without
 230                  * prefixing the base path
 231                  */
 232                 dir = directory;
 233                 path = enter_repo(dir, strict_paths);
 234         }
 235
 236         if (!path) {
 237                 logerror("'%s' does not appear to be a git repository", dir);
 238                 return NULL;
 239         }
 240
 241         if ( ok_paths && *ok_paths ) {
 242                 const char **pp;
 243                 int pathlen = strlen(path);
 244
 245                 /* The validation is done on the paths after enter_repo
 246                  * appends optional {.git,.git/.git} and friends, but
 247                  * it does not use getcwd().  So if your /pub is
 248                  * a symlink to /mnt/pub, you can whitelist /pub and
 249                  * do not have to say /mnt/pub.
 250                  * Do not say /pub/.
 251                  */
 252                 for ( pp = ok_paths ; *pp ; pp++ ) {
 253                         int len = strlen(*pp);
 254                         if (len <= pathlen &&
 255                             !memcmp(*pp, path, len) &&
 256                             (path[len] == '\0' ||
 257                              (!strict_paths && path[len] == '/')))
 258                                 return path;
 259                 }
 260         }
 261         else {
 262                 /* be backwards compatible */
 263                 if (!strict_paths)
 264                         return path;
 265         }
 266
 267         logerror("'%s': not in whitelist", path);
 268         return NULL;            /* Fallthrough. Deny by default */
 269 }
 270
 271 typedef int (*daemon_service_fn)(void);
 272 struct daemon_service {
 273         const char *name;
 274         const char *config_name;
 275         daemon_service_fn fn;
 276         int enabled;
 277         int overridable;
 278 };
 279
 280 static int daemon_error(const char *dir, const char *msg)
 281 {
 282         if (!informative_errors)
 283                 msg = "access denied or repository not exported";
 284         packet_write(1, "ERR %s: %s", msg, dir);
 285         return -1;
 286 }
 287
 288 static const char *access_hook;
 289
 290 static int run_access_hook(struct daemon_service *service, const char *dir,
 291                            const char *path, struct hostinfo *hi)
 292 {
 293         struct child_process child = CHILD_PROCESS_INIT;
 294         struct strbuf buf = STRBUF_INIT;
 295         const char *argv[8];
 296         const char **arg = argv;
 297         char *eol;
 298         int seen_errors = 0;
 299
 300         *arg++ = access_hook;
 301         *arg++ = service->name;
 302         *arg++ = path;
 303         *arg++ = hi->hostname.buf;
 304         *arg++ = get_canon_hostname(hi);
 305         *arg++ = get_ip_address(hi);
 306         *arg++ = hi->tcp_port.buf;
 307         *arg = NULL;
 308
 309         child.use_shell = 1;
 310         child.argv = argv;
 311         child.no_stdin = 1;
 312         child.no_stderr = 1;
 313         child.out = -1;
 314         if (start_command(&child)) {
 315                 logerror("daemon access hook '%s' failed to start",
 316                          access_hook);
 317                 goto error_return;
 318         }
 319         if (strbuf_read(&buf, child.out, 0) < 0) {
 320                 logerror("failed to read from pipe to daemon access hook '%s'",
 321                          access_hook);
 322                 strbuf_reset(&buf);
 323                 seen_errors = 1;
 324         }
 325         if (close(child.out) < 0) {
 326                 logerror("failed to close pipe to daemon access hook '%s'",
 327                          access_hook);
 328                 seen_errors = 1;
 329         }
 330         if (finish_command(&child))
 331                 seen_errors = 1;
 332
 333         if (!seen_errors) {
 334                 strbuf_release(&buf);
 335                 return 0;
 336         }
 337
 338 error_return:
 339         strbuf_ltrim(&buf);
 340         if (!buf.len)
 341                 strbuf_addstr(&buf, "service rejected");
 342         eol = strchr(buf.buf, '\n');
 343         if (eol)
 344                 *eol = '\0';
 345         errno = EACCES;
 346         daemon_error(dir, buf.buf);
 347         strbuf_release(&buf);
 348         return -1;
 349 }
 350
 351 static int run_service(const char *dir, struct daemon_service *service,
 352                        struct hostinfo *hi)
 353 {
 354         const char *path;
 355         int enabled = service->enabled;
 356         struct strbuf var = STRBUF_INIT;
 357
 358         loginfo("Request %s for '%s'", service->name, dir);
 359
 360         if (!enabled && !service->overridable) {
 361                 logerror("'%s': service not enabled.", service->name);
 362                 errno = EACCES;
 363                 return daemon_error(dir, "service not enabled");
 364         }
 365
 366         if (!(path = path_ok(dir, hi)))
 367                 return daemon_error(dir, "no such repository");
 368
 369         /*
 370          * Security on the cheap.
 371          *
 372          * We want a readable HEAD, usable "objects" directory, and
 373          * a "git-daemon-export-ok" flag that says that the other side
 374          * is ok with us doing this.
 375          *
 376          * path_ok() uses enter_repo() and does whitelist checking.
 377          * We only need to make sure the repository is exported.
 378          */
 379
 380         if (!export_all_trees && access("git-daemon-export-ok", F_OK)) {
 381                 logerror("'%s': repository not exported.", path);
 382                 errno = EACCES;
 383                 return daemon_error(dir, "repository not exported");
 384         }
 385
 386         if (service->overridable) {
 387                 strbuf_addf(&var, "daemon.%s", service->config_name);
 388                 git_config_get_bool(var.buf, &enabled);
 389                 strbuf_release(&var);
 390         }
 391         if (!enabled) {
 392                 logerror("'%s': service not enabled for '%s'",
 393                          service->name, path);
 394                 errno = EACCES;
 395                 return daemon_error(dir, "service not enabled");
 396         }
 397
 398         /*
 399          * Optionally, a hook can choose to deny access to the
 400          * repository depending on the phase of the moon.
 401          */
 402         if (access_hook && run_access_hook(service, dir, path, hi))
 403                 return -1;
 404
 405         /*
 406          * We'll ignore SIGTERM from now on, we have a
 407          * good client.
 408          */
 409         signal(SIGTERM, SIG_IGN);
 410
 411         return service->fn();
 412 }
 413
 414 static void copy_to_log(int fd)
 415 {
 416         struct strbuf line = STRBUF_INIT;
 417         FILE *fp;
 418
 419         fp = fdopen(fd, "r");
 420         if (fp == NULL) {
 421                 logerror("fdopen of error channel failed");
 422                 close(fd);
 423                 return;
 424         }
 425
 426         while (strbuf_getline_lf(&line, fp) != EOF) {
 427                 logerror("%s", line.buf);
 428                 strbuf_setlen(&line, 0);
 429         }
 430
 431         strbuf_release(&line);
 432         fclose(fp);
 433 }
 434
 435 static int run_service_command(const char **argv)
 436 {
 437         struct child_process cld = CHILD_PROCESS_INIT;
 438
 439         cld.argv = argv;
 440         cld.git_cmd = 1;
 441         cld.err = -1;
 442         if (start_command(&cld))
 443                 return -1;
 444
 445         close(0);
 446         close(1);
 447
 448         copy_to_log(cld.err);
 449
 450         return finish_command(&cld);
 451 }
 452
 453 static int upload_pack(void)
 454 {
 455         /* Timeout as string */
 456         char timeout_buf[64];
 457         const char *argv[] = { "upload-pack", "--strict", NULL, ".", NULL };
 458
 459         argv[2] = timeout_buf;
 460
 461         snprintf(timeout_buf, sizeof timeout_buf, "--timeout=%u", timeout);
 462         return run_service_command(argv);
 463 }
 464
 465 static int upload_archive(void)
 466 {
 467         static const char *argv[] = { "upload-archive", ".", NULL };
 468         return run_service_command(argv);
 469 }
 470
 471 static int receive_pack(void)
 472 {
 473         static const char *argv[] = { "receive-pack", ".", NULL };
 474         return run_service_command(argv);
 475 }
 476
 477 static struct daemon_service daemon_service[] = {
 478         { "upload-archive", "uploadarch", upload_archive, 0, 1 },
 479         { "upload-pack", "uploadpack", upload_pack, 1, 1 },
 480         { "receive-pack", "receivepack", receive_pack, 0, 1 },
 481 };
 482
 483 static void enable_service(const char *name, int ena)
 484 {
 485         int i;
 486         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 487                 if (!strcmp(daemon_service[i].name, name)) {
 488                         daemon_service[i].enabled = ena;
 489                         return;
 490                 }
 491         }
 492         die("No such service %s", name);
 493 }
 494
 495 static void make_service_overridable(const char *name, int ena)
 496 {
 497         int i;
 498         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 499                 if (!strcmp(daemon_service[i].name, name)) {
 500                         daemon_service[i].overridable = ena;
 501                         return;
 502                 }
 503         }
 504         die("No such service %s", name);
 505 }
 506
 507 static void parse_host_and_port(char *hostport, char **host,
 508         char **port)
 509 {
 510         if (*hostport == '[') {
 511                 char *end;
 512
 513                 end = strchr(hostport, ']');
 514                 if (!end)
 515                         die("Invalid request ('[' without ']')");
 516                 *end = '\0';
 517                 *host = hostport + 1;
 518                 if (!end[1])
 519                         *port = NULL;
 520                 else if (end[1] == ':')
 521                         *port = end + 2;
 522                 else
 523                         die("Garbage after end of host part");
 524         } else {
 525                 *host = hostport;
 526                 *port = strrchr(hostport, ':');
 527                 if (*port) {
 528                         **port = '\0';
 529                         ++*port;
 530                 }
 531         }
 532 }
 533
 534 /*
 535  * Sanitize a string from the client so that it's OK to be inserted into a
 536  * filesystem path. Specifically, we disallow slashes, runs of "..", and
 537  * trailing and leading dots, which means that the client cannot escape
 538  * our base path via ".." traversal.
 539  */
 540 static void sanitize_client(struct strbuf *out, const char *in)
 541 {
 542         for (; *in; in++) {
 543                 if (*in == '/')
 544                         continue;
 545                 if (*in == '.' && (!out->len || out->buf[out->len - 1] == '.'))
 546                         continue;
 547                 strbuf_addch(out, *in);
 548         }
 549
 550         while (out->len && out->buf[out->len - 1] == '.')
 551                 strbuf_setlen(out, out->len - 1);
 552 }
 553
 554 /*
 555  * Like sanitize_client, but we also perform any canonicalization
 556  * to make life easier on the admin.
 557  */
 558 static void canonicalize_client(struct strbuf *out, const char *in)
 559 {
 560         sanitize_client(out, in);
 561         strbuf_tolower(out);
 562 }
 563
 564 /*
 565  * Read the host as supplied by the client connection.
 566  */
 567 static void parse_host_arg(struct hostinfo *hi, char *extra_args, int buflen)
 568 {
 569         char *val;
 570         int vallen;
 571         char *end = extra_args + buflen;
 572
 573         if (extra_args < end && *extra_args) {
 574                 hi->saw_extended_args = 1;
 575                 if (strncasecmp("host=", extra_args, 5) == 0) {
 576                         val = extra_args + 5;
 577                         vallen = strlen(val) + 1;
 578                         if (*val) {
 579                                 /* Split <host>:<port> at colon. */
 580                                 char *host;
 581                                 char *port;
 582                                 parse_host_and_port(val, &host, &port);
 583                                 if (port)
 584                                         sanitize_client(&hi->tcp_port, port);
 585                                 canonicalize_client(&hi->hostname, host);
 586                                 hi->hostname_lookup_done = 0;
 587                         }
 588
 589                         /* On to the next one */
 590                         extra_args = val + vallen;
 591                 }
 592                 if (extra_args < end && *extra_args)
 593                         die("Invalid request");
 594         }
 595 }
 596
 597 /*
 598  * Locate canonical hostname and its IP address.
 599  */
 600 static void lookup_hostname(struct hostinfo *hi)
 601 {
 602         if (!hi->hostname_lookup_done && hi->hostname.len) {
 603 #ifndef NO_IPV6
 604                 struct addrinfo hints;
 605                 struct addrinfo *ai;
 606                 int gai;
 607                 static char addrbuf[HOST_NAME_MAX + 1];
 608
 609                 memset(&hints, 0, sizeof(hints));
 610                 hints.ai_flags = AI_CANONNAME;
 611
 612                 gai = getaddrinfo(hi->hostname.buf, NULL, &hints, &ai);
 613                 if (!gai) {
 614                         struct sockaddr_in *sin_addr = (void *)ai->ai_addr;
 615
 616                         inet_ntop(AF_INET, &sin_addr->sin_addr,
 617                                   addrbuf, sizeof(addrbuf));
 618                         strbuf_addstr(&hi->ip_address, addrbuf);
 619
 620                         if (ai->ai_canonname)
 621                                 sanitize_client(&hi->canon_hostname,
 622                                                 ai->ai_canonname);
 623                         else
 624                                 strbuf_addbuf(&hi->canon_hostname,
 625                                               &hi->ip_address);
 626
 627                         freeaddrinfo(ai);
 628                 }
 629 #else
 630                 struct hostent *hent;
 631                 struct sockaddr_in sa;
 632                 char **ap;
 633                 static char addrbuf[HOST_NAME_MAX + 1];
 634
 635                 hent = gethostbyname(hi->hostname.buf);
 636                 if (hent) {
 637                         ap = hent->h_addr_list;
 638                         memset(&sa, 0, sizeof sa);
 639                         sa.sin_family = hent->h_addrtype;
 640                         sa.sin_port = htons(0);
 641                         memcpy(&sa.sin_addr, *ap, hent->h_length);
 642
 643                         inet_ntop(hent->h_addrtype, &sa.sin_addr,
 644                                   addrbuf, sizeof(addrbuf));
 645
 646                         sanitize_client(&hi->canon_hostname, hent->h_name);
 647                         strbuf_addstr(&hi->ip_address, addrbuf);
 648                 }
 649 #endif
 650                 hi->hostname_lookup_done = 1;
 651         }
 652 }
 653
 654 static void hostinfo_init(struct hostinfo *hi)
 655 {
 656         memset(hi, 0, sizeof(*hi));
 657         strbuf_init(&hi->hostname, 0);
 658         strbuf_init(&hi->canon_hostname, 0);
 659         strbuf_init(&hi->ip_address, 0);
 660         strbuf_init(&hi->tcp_port, 0);
 661 }
 662
 663 static void hostinfo_clear(struct hostinfo *hi)
 664 {
 665         strbuf_release(&hi->hostname);
 666         strbuf_release(&hi->canon_hostname);
 667         strbuf_release(&hi->ip_address);
 668         strbuf_release(&hi->tcp_port);
 669 }
 670
 671 static void set_keep_alive(int sockfd)
 672 {
 673         int ka = 1;
 674
 675         if (setsockopt(sockfd, SOL_SOCKET, SO_KEEPALIVE, &ka, sizeof(ka)) < 0)
 676                 logerror("unable to set SO_KEEPALIVE on socket: %s",
 677                         strerror(errno));
 678 }
 679
 680 static int execute(void)
 681 {
 682         char *line = packet_buffer;
 683         int pktlen, len, i;
 684         char *addr = getenv("REMOTE_ADDR"), *port = getenv("REMOTE_PORT");
 685         struct hostinfo hi;
 686
 687         hostinfo_init(&hi);
 688
 689         if (addr)
 690                 loginfo("Connection from %s:%s", addr, port);
 691
 692         set_keep_alive(0);
 693         alarm(init_timeout ? init_timeout : timeout);
 694         pktlen = packet_read(0, NULL, NULL, packet_buffer, sizeof(packet_buffer), 0);
 695         alarm(0);
 696
 697         len = strlen(line);
 698         if (pktlen != len)
 699                 loginfo("Extended attributes (%d bytes) exist <%.*s>",
 700                         (int) pktlen - len,
 701                         (int) pktlen - len, line + len + 1);
 702         if (len && line[len-1] == '\n') {
 703                 line[--len] = 0;
 704                 pktlen--;
 705         }
 706
 707         if (len != pktlen)
 708                 parse_host_arg(&hi, line + len + 1, pktlen - len - 1);
 709
 710         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 711                 struct daemon_service *s = &(daemon_service[i]);
 712                 const char *arg;
 713
 714                 if (skip_prefix(line, "git-", &arg) &&
 715                     skip_prefix(arg, s->name, &arg) &&
 716                     *arg++ == ' ') {
 717                         /*
 718                          * Note: The directory here is probably context sensitive,
 719                          * and might depend on the actual service being performed.
 720                          */
 721                         int rc = run_service(arg, s, &hi);
 722                         hostinfo_clear(&hi);
 723                         return rc;
 724                 }
 725         }
 726
 727         hostinfo_clear(&hi);
 728         logerror("Protocol error: '%s'", line);
 729         return -1;
 730 }
 731
 732 static int addrcmp(const struct sockaddr_storage *s1,
 733     const struct sockaddr_storage *s2)
 734 {
 735         const struct sockaddr *sa1 = (const struct sockaddr*) s1;
 736         const struct sockaddr *sa2 = (const struct sockaddr*) s2;
 737
 738         if (sa1->sa_family != sa2->sa_family)
 739                 return sa1->sa_family - sa2->sa_family;
 740         if (sa1->sa_family == AF_INET)
 741                 return memcmp(&((struct sockaddr_in *)s1)->sin_addr,
 742                     &((struct sockaddr_in *)s2)->sin_addr,
 743                     sizeof(struct in_addr));
 744 #ifndef NO_IPV6
 745         if (sa1->sa_family == AF_INET6)
 746                 return memcmp(&((struct sockaddr_in6 *)s1)->sin6_addr,
 747                     &((struct sockaddr_in6 *)s2)->sin6_addr,
 748                     sizeof(struct in6_addr));
 749 #endif
 750         return 0;
 751 }
 752
 753 static int max_connections = 32;
 754
 755 static unsigned int live_children;
 756
 757 static struct child {
 758         struct child *next;
 759         struct child_process cld;
 760         struct sockaddr_storage address;
 761 } *firstborn;
 762
 763 static void add_child(struct child_process *cld, struct sockaddr *addr, socklen_t addrlen)
 764 {
 765         struct child *newborn, **cradle;
 766
 767         newborn = xcalloc(1, sizeof(*newborn));
 768         live_children++;
 769         memcpy(&newborn->cld, cld, sizeof(*cld));
 770         memcpy(&newborn->address, addr, addrlen);
 771         for (cradle = &firstborn; *cradle; cradle = &(*cradle)->next)
 772                 if (!addrcmp(&(*cradle)->address, &newborn->address))
 773                         break;
 774         newborn->next = *cradle;
 775         *cradle = newborn;
 776 }
 777
 778 /*
 779  * This gets called if the number of connections grows
 780  * past "max_connections".
 781  *
 782  * We kill the newest connection from a duplicate IP.
 783  */
 784 static void kill_some_child(void)
 785 {
 786         const struct child *blanket, *next;
 787
 788         if (!(blanket = firstborn))
 789                 return;
 790
 791         for (; (next = blanket->next); blanket = next)
 792                 if (!addrcmp(&blanket->address, &next->address)) {
 793                         kill(blanket->cld.pid, SIGTERM);
 794                         break;
 795                 }
 796 }
 797
 798 static void check_dead_children(void)
 799 {
 800         int status;
 801         pid_t pid;
 802
 803         struct child **cradle, *blanket;
 804         for (cradle = &firstborn; (blanket = *cradle);)
 805                 if ((pid = waitpid(blanket->cld.pid, &status, WNOHANG)) > 1) {
 806                         const char *dead = "";
 807                         if (status)
 808                                 dead = " (with error)";
 809                         loginfo("[%"PRIuMAX"] Disconnected%s", (uintmax_t)pid, dead);
 810
 811                         /* remove the child */
 812                         *cradle = blanket->next;
 813                         live_children--;
 814                         child_process_clear(&blanket->cld);
 815                         free(blanket);
 816                 } else
 817                         cradle = &blanket->next;
 818 }
 819
 820 static struct argv_array cld_argv = ARGV_ARRAY_INIT;
 821 static void handle(int incoming, struct sockaddr *addr, socklen_t addrlen)
 822 {
 823         struct child_process cld = CHILD_PROCESS_INIT;
 824
 825         if (max_connections && live_children >= max_connections) {
 826                 kill_some_child();
 827                 sleep(1);  /* give it some time to die */
 828                 check_dead_children();
 829                 if (live_children >= max_connections) {
 830                         close(incoming);
 831                         logerror("Too many children, dropping connection");
 832                         return;
 833                 }
 834         }
 835
 836         if (addr->sa_family == AF_INET) {
 837                 char buf[128] = "";
 838                 struct sockaddr_in *sin_addr = (void *) addr;
 839                 inet_ntop(addr->sa_family, &sin_addr->sin_addr, buf, sizeof(buf));
 840                 argv_array_pushf(&cld.env_array, "REMOTE_ADDR=%s", buf);
 841                 argv_array_pushf(&cld.env_array, "REMOTE_PORT=%d",
 842                                  ntohs(sin_addr->sin_port));
 843 #ifndef NO_IPV6
 844         } else if (addr->sa_family == AF_INET6) {
 845                 char buf[128] = "";
 846                 struct sockaddr_in6 *sin6_addr = (void *) addr;
 847                 inet_ntop(AF_INET6, &sin6_addr->sin6_addr, buf, sizeof(buf));
 848                 argv_array_pushf(&cld.env_array, "REMOTE_ADDR=[%s]", buf);
 849                 argv_array_pushf(&cld.env_array, "REMOTE_PORT=%d",
 850                                  ntohs(sin6_addr->sin6_port));
 851 #endif
 852         }
 853
 854         cld.argv = cld_argv.argv;
 855         cld.in = incoming;
 856         cld.out = dup(incoming);
 857
 858         if (start_command(&cld))
 859                 logerror("unable to fork");
 860         else
 861                 add_child(&cld, addr, addrlen);
 862 }
 863
 864 static void child_handler(int signo)
 865 {
 866         /*
 867          * Otherwise empty handler because systemcalls will get interrupted
 868          * upon signal receipt
 869          * SysV needs the handler to be rearmed
 870          */
 871         signal(SIGCHLD, child_handler);
 872 }
 873
 874 static int set_reuse_addr(int sockfd)
 875 {
 876         int on = 1;
 877
 878         if (!reuseaddr)
 879                 return 0;
 880         return setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
 881                           &on, sizeof(on));
 882 }
 883
 884 struct socketlist {
 885         int *list;
 886         size_t nr;
 887         size_t alloc;
 888 };
 889
 890 static const char *ip2str(int family, struct sockaddr *sin, socklen_t len)
 891 {
 892 #ifdef NO_IPV6
 893         static char ip[INET_ADDRSTRLEN];
 894 #else
 895         static char ip[INET6_ADDRSTRLEN];
 896 #endif
 897
 898         switch (family) {
 899 #ifndef NO_IPV6
 900         case AF_INET6:
 901                 inet_ntop(family, &((struct sockaddr_in6*)sin)->sin6_addr, ip, len);
 902                 break;
 903 #endif
 904         case AF_INET:
 905                 inet_ntop(family, &((struct sockaddr_in*)sin)->sin_addr, ip, len);
 906                 break;
 907         default:
 908                 xsnprintf(ip, sizeof(ip), "<unknown>");
 909         }
 910         return ip;
 911 }
 912
 913 #ifndef NO_IPV6
 914
 915 static int setup_named_sock(char *listen_addr, int listen_port, struct socketlist *socklist)
 916 {
 917         int socknum = 0;
 918         char pbuf[NI_MAXSERV];
 919         struct addrinfo hints, *ai0, *ai;
 920         int gai;
 921         long flags;
 922
 923         xsnprintf(pbuf, sizeof(pbuf), "%d", listen_port);
 924         memset(&hints, 0, sizeof(hints));
 925         hints.ai_family = AF_UNSPEC;
 926         hints.ai_socktype = SOCK_STREAM;
 927         hints.ai_protocol = IPPROTO_TCP;
 928         hints.ai_flags = AI_PASSIVE;
 929
 930         gai = getaddrinfo(listen_addr, pbuf, &hints, &ai0);
 931         if (gai) {
 932                 logerror("getaddrinfo() for %s failed: %s", listen_addr, gai_strerror(gai));
 933                 return 0;
 934         }
 935
 936         for (ai = ai0; ai; ai = ai->ai_next) {
 937                 int sockfd;
 938
 939                 sockfd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
 940                 if (sockfd < 0)
 941                         continue;
 942                 if (sockfd >= FD_SETSIZE) {
 943                         logerror("Socket descriptor too large");
 944                         close(sockfd);
 945                         continue;
 946                 }
 947
 948 #ifdef IPV6_V6ONLY
 949                 if (ai->ai_family == AF_INET6) {
 950                         int on = 1;
 951                         setsockopt(sockfd, IPPROTO_IPV6, IPV6_V6ONLY,
 952                                    &on, sizeof(on));
 953                         /* Note: error is not fatal */
 954                 }
 955 #endif
 956
 957                 if (set_reuse_addr(sockfd)) {
 958                         logerror("Could not set SO_REUSEADDR: %s", strerror(errno));
 959                         close(sockfd);
 960                         continue;
 961                 }
 962
 963                 set_keep_alive(sockfd);
 964
 965                 if (bind(sockfd, ai->ai_addr, ai->ai_addrlen) < 0) {
 966                         logerror("Could not bind to %s: %s",
 967                                  ip2str(ai->ai_family, ai->ai_addr, ai->ai_addrlen),
 968                                  strerror(errno));
 969                         close(sockfd);
 970                         continue;       /* not fatal */
 971                 }
 972                 if (listen(sockfd, 5) < 0) {
 973                         logerror("Could not listen to %s: %s",
 974                                  ip2str(ai->ai_family, ai->ai_addr, ai->ai_addrlen),
 975                                  strerror(errno));
 976                         close(sockfd);
 977                         continue;       /* not fatal */
 978                 }
 979
 980                 flags = fcntl(sockfd, F_GETFD, 0);
 981                 if (flags >= 0)
 982                         fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
 983
 984                 ALLOC_GROW(socklist->list, socklist->nr + 1, socklist->alloc);
 985                 socklist->list[socklist->nr++] = sockfd;
 986                 socknum++;
 987         }
 988
 989         freeaddrinfo(ai0);
 990
 991         return socknum;
 992 }
 993
 994 #else /* NO_IPV6 */
 995
 996 static int setup_named_sock(char *listen_addr, int listen_port, struct socketlist *socklist)
 997 {
 998         struct sockaddr_in sin;
 999         int sockfd;
1000         long flags;
1001
1002         memset(&sin, 0, sizeof sin);
1003         sin.sin_family = AF_INET;
1004         sin.sin_port = htons(listen_port);
1005
1006         if (listen_addr) {
1007                 /* Well, host better be an IP address here. */
1008                 if (inet_pton(AF_INET, listen_addr, &sin.sin_addr.s_addr) <= 0)
1009                         return 0;
1010         } else {
1011                 sin.sin_addr.s_addr = htonl(INADDR_ANY);
1012         }
1013
1014         sockfd = socket(AF_INET, SOCK_STREAM, 0);
1015         if (sockfd < 0)
1016                 return 0;
1017
1018         if (set_reuse_addr(sockfd)) {
1019                 logerror("Could not set SO_REUSEADDR: %s", strerror(errno));
1020                 close(sockfd);
1021                 return 0;
1022         }
1023
1024         set_keep_alive(sockfd);
1025
1026         if ( bind(sockfd, (struct sockaddr *)&sin, sizeof sin) < 0 ) {
1027                 logerror("Could not bind to %s: %s",
1028                          ip2str(AF_INET, (struct sockaddr *)&sin, sizeof(sin)),
1029                          strerror(errno));
1030                 close(sockfd);
1031                 return 0;
1032         }
1033
1034         if (listen(sockfd, 5) < 0) {
1035                 logerror("Could not listen to %s: %s",
1036                          ip2str(AF_INET, (struct sockaddr *)&sin, sizeof(sin)),
1037                          strerror(errno));
1038                 close(sockfd);
1039                 return 0;
1040         }
1041
1042         flags = fcntl(sockfd, F_GETFD, 0);
1043         if (flags >= 0)
1044                 fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
1045
1046         ALLOC_GROW(socklist->list, socklist->nr + 1, socklist->alloc);
1047         socklist->list[socklist->nr++] = sockfd;
1048         return 1;
1049 }
1050
1051 #endif
1052
1053 static void socksetup(struct string_list *listen_addr, int listen_port, struct socketlist *socklist)
1054 {
1055         if (!listen_addr->nr)
1056                 setup_named_sock(NULL, listen_port, socklist);
1057         else {
1058                 int i, socknum;
1059                 for (i = 0; i < listen_addr->nr; i++) {
1060                         socknum = setup_named_sock(listen_addr->items[i].string,
1061                                                    listen_port, socklist);
1062
1063                         if (socknum == 0)
1064                                 logerror("unable to allocate any listen sockets for host %s on port %u",
1065                                          listen_addr->items[i].string, listen_port);
1066                 }
1067         }
1068 }
1069
1070 static int service_loop(struct socketlist *socklist)
1071 {
1072         struct pollfd *pfd;
1073         int i;
1074
1075         pfd = xcalloc(socklist->nr, sizeof(struct pollfd));
1076
1077         for (i = 0; i < socklist->nr; i++) {
1078                 pfd[i].fd = socklist->list[i];
1079                 pfd[i].events = POLLIN;
1080         }
1081
1082         signal(SIGCHLD, child_handler);
1083
1084         for (;;) {
1085                 int i;
1086
1087                 check_dead_children();
1088
1089                 if (poll(pfd, socklist->nr, -1) < 0) {
1090                         if (errno != EINTR) {
1091                                 logerror("Poll failed, resuming: %s",
1092                                       strerror(errno));
1093                                 sleep(1);
1094                         }
1095                         continue;
1096                 }
1097
1098                 for (i = 0; i < socklist->nr; i++) {
1099                         if (pfd[i].revents & POLLIN) {
1100                                 union {
1101                                         struct sockaddr sa;
1102                                         struct sockaddr_in sai;
1103 #ifndef NO_IPV6
1104                                         struct sockaddr_in6 sai6;
1105 #endif
1106                                 } ss;
1107                                 socklen_t sslen = sizeof(ss);
1108                                 int incoming = accept(pfd[i].fd, &ss.sa, &sslen);
1109                                 if (incoming < 0) {
1110                                         switch (errno) {
1111                                         case EAGAIN:
1112                                         case EINTR:
1113                                         case ECONNABORTED:
1114                                                 continue;
1115                                         default:
1116                                                 die_errno("accept returned");
1117                                         }
1118                                 }
1119                                 handle(incoming, &ss.sa, sslen);
1120                         }
1121                 }
1122         }
1123 }
1124
1125 #ifdef NO_POSIX_GOODIES
1126
1127 struct credentials;
1128
1129 static void drop_privileges(struct credentials *cred)
1130 {
1131         /* nothing */
1132 }
1133
1134 static struct credentials *prepare_credentials(const char *user_name,
1135     const char *group_name)
1136 {
1137         die("--user not supported on this platform");
1138 }
1139
1140 #else
1141
1142 struct credentials {
1143         struct passwd *pass;
1144         gid_t gid;
1145 };
1146
1147 static void drop_privileges(struct credentials *cred)
1148 {
1149         if (cred && (initgroups(cred->pass->pw_name, cred->gid) ||
1150             setgid (cred->gid) || setuid(cred->pass->pw_uid)))
1151                 die("cannot drop privileges");
1152 }
1153
1154 static struct credentials *prepare_credentials(const char *user_name,
1155     const char *group_name)
1156 {
1157         static struct credentials c;
1158
1159         c.pass = getpwnam(user_name);
1160         if (!c.pass)
1161                 die("user not found - %s", user_name);
1162
1163         if (!group_name)
1164                 c.gid = c.pass->pw_gid;
1165         else {
1166                 struct group *group = getgrnam(group_name);
1167                 if (!group)
1168                         die("group not found - %s", group_name);
1169
1170                 c.gid = group->gr_gid;
1171         }
1172
1173         return &c;
1174 }
1175 #endif
1176
1177 static int serve(struct string_list *listen_addr, int listen_port,
1178     struct credentials *cred)
1179 {
1180         struct socketlist socklist = { NULL, 0, 0 };
1181
1182         socksetup(listen_addr, listen_port, &socklist);
1183         if (socklist.nr == 0)
1184                 die("unable to allocate any listen sockets on port %u",
1185                     listen_port);
1186
1187         drop_privileges(cred);
1188
1189         loginfo("Ready to rumble");
1190
1191         return service_loop(&socklist);
1192 }
1193
1194 int cmd_main(int argc, const char **argv)
1195 {
1196         int listen_port = 0;
1197         struct string_list listen_addr = STRING_LIST_INIT_NODUP;
1198         int serve_mode = 0, inetd_mode = 0;
1199         const char *pid_file = NULL, *user_name = NULL, *group_name = NULL;
1200         int detach = 0;
1201         struct credentials *cred = NULL;
1202         int i;
1203
1204         for (i = 1; i < argc; i++) {
1205                 const char *arg = argv[i];
1206                 const char *v;
1207
1208                 if (skip_prefix(arg, "--listen=", &v)) {
1209                         string_list_append(&listen_addr, xstrdup_tolower(v));
1210                         continue;
1211                 }
1212                 if (skip_prefix(arg, "--port=", &v)) {
1213                         char *end;
1214                         unsigned long n;
1215                         n = strtoul(v, &end, 0);
1216                         if (*v && !*end) {
1217                                 listen_port = n;
1218                                 continue;
1219                         }
1220                 }
1221                 if (!strcmp(arg, "--serve")) {
1222                         serve_mode = 1;
1223                         continue;
1224                 }
1225                 if (!strcmp(arg, "--inetd")) {
1226                         inetd_mode = 1;
1227                         log_syslog = 1;
1228                         continue;
1229                 }
1230                 if (!strcmp(arg, "--verbose")) {
1231                         verbose = 1;
1232                         continue;
1233                 }
1234                 if (!strcmp(arg, "--syslog")) {
1235                         log_syslog = 1;
1236                         continue;
1237                 }
1238                 if (!strcmp(arg, "--export-all")) {
1239                         export_all_trees = 1;
1240                         continue;
1241                 }
1242                 if (skip_prefix(arg, "--access-hook=", &v)) {
1243                         access_hook = v;
1244                         continue;
1245                 }
1246                 if (skip_prefix(arg, "--timeout=", &v)) {
1247                         timeout = atoi(v);
1248                         continue;
1249                 }
1250                 if (skip_prefix(arg, "--init-timeout=", &v)) {
1251                         init_timeout = atoi(v);
1252                         continue;
1253                 }
1254                 if (skip_prefix(arg, "--max-connections=", &v)) {
1255                         max_connections = atoi(v);
1256                         if (max_connections < 0)
1257                                 max_connections = 0;            /* unlimited */
1258                         continue;
1259                 }
1260                 if (!strcmp(arg, "--strict-paths")) {
1261                         strict_paths = 1;
1262                         continue;
1263                 }
1264                 if (skip_prefix(arg, "--base-path=", &v)) {
1265                         base_path = v;
1266                         continue;
1267                 }
1268                 if (!strcmp(arg, "--base-path-relaxed")) {
1269                         base_path_relaxed = 1;
1270                         continue;
1271                 }
1272                 if (skip_prefix(arg, "--interpolated-path=", &v)) {
1273                         interpolated_path = v;
1274                         continue;
1275                 }
1276                 if (!strcmp(arg, "--reuseaddr")) {
1277                         reuseaddr = 1;
1278                         continue;
1279                 }
1280                 if (!strcmp(arg, "--user-path")) {
1281                         user_path = "";
1282                         continue;
1283                 }
1284                 if (skip_prefix(arg, "--user-path=", &v)) {
1285                         user_path = v;
1286                         continue;
1287                 }
1288                 if (skip_prefix(arg, "--pid-file=", &v)) {
1289                         pid_file = v;
1290                         continue;
1291                 }
1292                 if (!strcmp(arg, "--detach")) {
1293                         detach = 1;
1294                         log_syslog = 1;
1295                         continue;
1296                 }
1297                 if (skip_prefix(arg, "--user=", &v)) {
1298                         user_name = v;
1299                         continue;
1300                 }
1301                 if (skip_prefix(arg, "--group=", &v)) {
1302                         group_name = v;
1303                         continue;
1304                 }
1305                 if (skip_prefix(arg, "--enable=", &v)) {
1306                         enable_service(v, 1);
1307                         continue;
1308                 }
1309                 if (skip_prefix(arg, "--disable=", &v)) {
1310                         enable_service(v, 0);
1311                         continue;
1312                 }
1313                 if (skip_prefix(arg, "--allow-override=", &v)) {
1314                         make_service_overridable(v, 1);
1315                         continue;
1316                 }
1317                 if (skip_prefix(arg, "--forbid-override=", &v)) {
1318                         make_service_overridable(v, 0);
1319                         continue;
1320                 }
1321                 if (!strcmp(arg, "--informative-errors")) {
1322                         informative_errors = 1;
1323                         continue;
1324                 }
1325                 if (!strcmp(arg, "--no-informative-errors")) {
1326                         informative_errors = 0;
1327                         continue;
1328                 }
1329                 if (!strcmp(arg, "--")) {
1330                         ok_paths = &argv[i+1];
1331                         break;
1332                 } else if (arg[0] != '-') {
1333                         ok_paths = &argv[i];
1334                         break;
1335                 }
1336
1337                 usage(daemon_usage);
1338         }
1339
1340         if (log_syslog) {
1341                 openlog("git-daemon", LOG_PID, LOG_DAEMON);
1342                 set_die_routine(daemon_die);
1343         } else
1344                 /* avoid splitting a message in the middle */
1345                 setvbuf(stderr, NULL, _IOFBF, 4096);
1346
1347         if (inetd_mode && (detach || group_name || user_name))
1348                 die("--detach, --user and --group are incompatible with --inetd");
1349
1350         if (inetd_mode && (listen_port || (listen_addr.nr > 0)))
1351                 die("--listen= and --port= are incompatible with --inetd");
1352         else if (listen_port == 0)
1353                 listen_port = DEFAULT_GIT_PORT;
1354
1355         if (group_name && !user_name)
1356                 die("--group supplied without --user");
1357
1358         if (user_name)
1359                 cred = prepare_credentials(user_name, group_name);
1360
1361         if (strict_paths && (!ok_paths || !*ok_paths))
1362                 die("option --strict-paths requires a whitelist");
1363
1364         if (base_path && !is_directory(base_path))
1365                 die("base-path '%s' does not exist or is not a directory",
1366                     base_path);
1367
1368         if (inetd_mode) {
1369                 if (!freopen("/dev/null", "w", stderr))
1370                         die_errno("failed to redirect stderr to /dev/null");
1371         }
1372
1373         if (inetd_mode || serve_mode)
1374                 return execute();
1375
1376         if (detach) {
1377                 if (daemonize())
1378                         die("--detach not supported on this platform");
1379         }
1380
1381         if (pid_file)
1382                 write_file(pid_file, "%"PRIuMAX, (uintmax_t) getpid());
1383
1384         /* prepare argv for serving-processes */
1385         argv_array_push(&cld_argv, argv[0]); /* git-daemon */
1386         argv_array_push(&cld_argv, "--serve");
1387         for (i = 1; i < argc; ++i)
1388                 argv_array_push(&cld_argv, argv[i]);
1389
1390         return serve(&listen_addr, listen_port, cred);
1391 }