daemon.con commit Update my e-mail address (1ceb95c)
   1#include "cache.h"
   2#include "pkt-line.h"
   3#include "exec_cmd.h"
   4#include "interpolate.h"
   5
   6#include <syslog.h>
   7
   8#ifndef HOST_NAME_MAX
   9#define HOST_NAME_MAX 256
  10#endif
  11
  12#ifndef NI_MAXSERV
  13#define NI_MAXSERV 32
  14#endif
  15
  16static int log_syslog;
  17static int verbose;
  18static int reuseaddr;
  19
  20static const char daemon_usage[] =
  21"git-daemon [--verbose] [--syslog] [--export-all]\n"
  22"           [--timeout=n] [--init-timeout=n] [--strict-paths]\n"
  23"           [--base-path=path] [--base-path-relaxed]\n"
  24"           [--user-path | --user-path=path]\n"
  25"           [--interpolated-path=path]\n"
  26"           [--reuseaddr] [--detach] [--pid-file=file]\n"
  27"           [--[enable|disable|allow-override|forbid-override]=service]\n"
  28"           [--inetd | [--listen=host_or_ipaddr] [--port=n]\n"
  29"                      [--user=user [--group=group]]\n"
  30"           [directory...]";
  31
  32/* List of acceptable pathname prefixes */
  33static char **ok_paths;
  34static int strict_paths;
  35
  36/* If this is set, git-daemon-export-ok is not required */
  37static int export_all_trees;
  38
  39/* Take all paths relative to this one if non-NULL */
  40static char *base_path;
  41static char *interpolated_path;
  42static int base_path_relaxed;
  43
  44/* Flag indicating client sent extra args. */
  45static int saw_extended_args;
  46
  47/* If defined, ~user notation is allowed and the string is inserted
  48 * after ~user/.  E.g. a request to git://host/~alice/frotz would
  49 * go to /home/alice/pub_git/frotz with --user-path=pub_git.
  50 */
  51static const char *user_path;
  52
  53/* Timeout, and initial timeout */
  54static unsigned int timeout;
  55static unsigned int init_timeout;
  56
  57/*
  58 * Static table for now.  Ugh.
  59 * Feel free to make dynamic as needed.
  60 */
  61#define INTERP_SLOT_HOST        (0)
  62#define INTERP_SLOT_CANON_HOST  (1)
  63#define INTERP_SLOT_IP          (2)
  64#define INTERP_SLOT_PORT        (3)
  65#define INTERP_SLOT_DIR         (4)
  66#define INTERP_SLOT_PERCENT     (5)
  67
  68static struct interp interp_table[] = {
  69        { "%H", 0},
  70        { "%CH", 0},
  71        { "%IP", 0},
  72        { "%P", 0},
  73        { "%D", 0},
  74        { "%%", 0},
  75};
  76
  77
  78static void logreport(int priority, const char *err, va_list params)
  79{
  80        /* We should do a single write so that it is atomic and output
  81         * of several processes do not get intermingled. */
  82        char buf[1024];
  83        int buflen;
  84        int maxlen, msglen;
  85
  86        /* sizeof(buf) should be big enough for "[pid] \n" */
  87        buflen = snprintf(buf, sizeof(buf), "[%ld] ", (long) getpid());
  88
  89        maxlen = sizeof(buf) - buflen - 1; /* -1 for our own LF */
  90        msglen = vsnprintf(buf + buflen, maxlen, err, params);
  91
  92        if (log_syslog) {
  93                syslog(priority, "%s", buf);
  94                return;
  95        }
  96
  97        /* maxlen counted our own LF but also counts space given to
  98         * vsnprintf for the terminating NUL.  We want to make sure that
  99         * we have space for our own LF and NUL after the "meat" of the
 100         * message, so truncate it at maxlen - 1.
 101         */
 102        if (msglen > maxlen - 1)
 103                msglen = maxlen - 1;
 104        else if (msglen < 0)
 105                msglen = 0; /* Protect against weird return values. */
 106        buflen += msglen;
 107
 108        buf[buflen++] = '\n';
 109        buf[buflen] = '\0';
 110
 111        write_in_full(2, buf, buflen);
 112}
 113
 114static void logerror(const char *err, ...)
 115{
 116        va_list params;
 117        va_start(params, err);
 118        logreport(LOG_ERR, err, params);
 119        va_end(params);
 120}
 121
 122static void loginfo(const char *err, ...)
 123{
 124        va_list params;
 125        if (!verbose)
 126                return;
 127        va_start(params, err);
 128        logreport(LOG_INFO, err, params);
 129        va_end(params);
 130}
 131
 132static void NORETURN daemon_die(const char *err, va_list params)
 133{
 134        logreport(LOG_ERR, err, params);
 135        exit(1);
 136}
 137
 138static int avoid_alias(char *p)
 139{
 140        int sl, ndot;
 141
 142        /*
 143         * This resurrects the belts and suspenders paranoia check by HPA
 144         * done in <435560F7.4080006@zytor.com> thread, now enter_repo()
 145         * does not do getcwd() based path canonicalizations.
 146         *
 147         * sl becomes true immediately after seeing '/' and continues to
 148         * be true as long as dots continue after that without intervening
 149         * non-dot character.
 150         */
 151        if (!p || (*p != '/' && *p != '~'))
 152                return -1;
 153        sl = 1; ndot = 0;
 154        p++;
 155
 156        while (1) {
 157                char ch = *p++;
 158                if (sl) {
 159                        if (ch == '.')
 160                                ndot++;
 161                        else if (ch == '/') {
 162                                if (ndot < 3)
 163                                        /* reject //, /./ and /../ */
 164                                        return -1;
 165                                ndot = 0;
 166                        }
 167                        else if (ch == 0) {
 168                                if (0 < ndot && ndot < 3)
 169                                        /* reject /.$ and /..$ */
 170                                        return -1;
 171                                return 0;
 172                        }
 173                        else
 174                                sl = ndot = 0;
 175                }
 176                else if (ch == 0)
 177                        return 0;
 178                else if (ch == '/') {
 179                        sl = 1;
 180                        ndot = 0;
 181                }
 182        }
 183}
 184
 185static char *path_ok(struct interp *itable)
 186{
 187        static char rpath[PATH_MAX];
 188        static char interp_path[PATH_MAX];
 189        int retried_path = 0;
 190        char *path;
 191        char *dir;
 192
 193        dir = itable[INTERP_SLOT_DIR].value;
 194
 195        if (avoid_alias(dir)) {
 196                logerror("'%s': aliased", dir);
 197                return NULL;
 198        }
 199
 200        if (*dir == '~') {
 201                if (!user_path) {
 202                        logerror("'%s': User-path not allowed", dir);
 203                        return NULL;
 204                }
 205                if (*user_path) {
 206                        /* Got either "~alice" or "~alice/foo";
 207                         * rewrite them to "~alice/%s" or
 208                         * "~alice/%s/foo".
 209                         */
 210                        int namlen, restlen = strlen(dir);
 211                        char *slash = strchr(dir, '/');
 212                        if (!slash)
 213                                slash = dir + restlen;
 214                        namlen = slash - dir;
 215                        restlen -= namlen;
 216                        loginfo("userpath <%s>, request <%s>, namlen %d, restlen %d, slash <%s>", user_path, dir, namlen, restlen, slash);
 217                        snprintf(rpath, PATH_MAX, "%.*s/%s%.*s",
 218                                 namlen, dir, user_path, restlen, slash);
 219                        dir = rpath;
 220                }
 221        }
 222        else if (interpolated_path && saw_extended_args) {
 223                if (*dir != '/') {
 224                        /* Allow only absolute */
 225                        logerror("'%s': Non-absolute path denied (interpolated-path active)", dir);
 226                        return NULL;
 227                }
 228
 229                interpolate(interp_path, PATH_MAX, interpolated_path,
 230                            interp_table, ARRAY_SIZE(interp_table));
 231                loginfo("Interpolated dir '%s'", interp_path);
 232
 233                dir = interp_path;
 234        }
 235        else if (base_path) {
 236                if (*dir != '/') {
 237                        /* Allow only absolute */
 238                        logerror("'%s': Non-absolute path denied (base-path active)", dir);
 239                        return NULL;
 240                }
 241                snprintf(rpath, PATH_MAX, "%s%s", base_path, dir);
 242                dir = rpath;
 243        }
 244
 245        do {
 246                path = enter_repo(dir, strict_paths);
 247                if (path)
 248                        break;
 249
 250                /*
 251                 * if we fail and base_path_relaxed is enabled, try without
 252                 * prefixing the base path
 253                 */
 254                if (base_path && base_path_relaxed && !retried_path) {
 255                        dir = itable[INTERP_SLOT_DIR].value;
 256                        retried_path = 1;
 257                        continue;
 258                }
 259                break;
 260        } while (1);
 261
 262        if (!path) {
 263                logerror("'%s': unable to chdir or not a git archive", dir);
 264                return NULL;
 265        }
 266
 267        if ( ok_paths && *ok_paths ) {
 268                char **pp;
 269                int pathlen = strlen(path);
 270
 271                /* The validation is done on the paths after enter_repo
 272                 * appends optional {.git,.git/.git} and friends, but
 273                 * it does not use getcwd().  So if your /pub is
 274                 * a symlink to /mnt/pub, you can whitelist /pub and
 275                 * do not have to say /mnt/pub.
 276                 * Do not say /pub/.
 277                 */
 278                for ( pp = ok_paths ; *pp ; pp++ ) {
 279                        int len = strlen(*pp);
 280                        if (len <= pathlen &&
 281                            !memcmp(*pp, path, len) &&
 282                            (path[len] == '\0' ||
 283                             (!strict_paths && path[len] == '/')))
 284                                return path;
 285                }
 286        }
 287        else {
 288                /* be backwards compatible */
 289                if (!strict_paths)
 290                        return path;
 291        }
 292
 293        logerror("'%s': not in whitelist", path);
 294        return NULL;            /* Fallthrough. Deny by default */
 295}
 296
 297typedef int (*daemon_service_fn)(void);
 298struct daemon_service {
 299        const char *name;
 300        const char *config_name;
 301        daemon_service_fn fn;
 302        int enabled;
 303        int overridable;
 304};
 305
 306static struct daemon_service *service_looking_at;
 307static int service_enabled;
 308
 309static int git_daemon_config(const char *var, const char *value, void *cb)
 310{
 311        if (!prefixcmp(var, "daemon.") &&
 312            !strcmp(var + 7, service_looking_at->config_name)) {
 313                service_enabled = git_config_bool(var, value);
 314                return 0;
 315        }
 316
 317        /* we are not interested in parsing any other configuration here */
 318        return 0;
 319}
 320
 321static int run_service(struct interp *itable, struct daemon_service *service)
 322{
 323        const char *path;
 324        int enabled = service->enabled;
 325
 326        loginfo("Request %s for '%s'",
 327                service->name,
 328                itable[INTERP_SLOT_DIR].value);
 329
 330        if (!enabled && !service->overridable) {
 331                logerror("'%s': service not enabled.", service->name);
 332                errno = EACCES;
 333                return -1;
 334        }
 335
 336        if (!(path = path_ok(itable)))
 337                return -1;
 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 -1;
 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 -1;
 368        }
 369
 370        /*
 371         * We'll ignore SIGTERM from now on, we have a
 372         * good client.
 373         */
 374        signal(SIGTERM, SIG_IGN);
 375
 376        return service->fn();
 377}
 378
 379static int upload_pack(void)
 380{
 381        /* Timeout as string */
 382        char timeout_buf[64];
 383
 384        snprintf(timeout_buf, sizeof timeout_buf, "--timeout=%u", timeout);
 385
 386        /* git-upload-pack only ever reads stuff, so this is safe */
 387        execl_git_cmd("upload-pack", "--strict", timeout_buf, ".", NULL);
 388        return -1;
 389}
 390
 391static int upload_archive(void)
 392{
 393        execl_git_cmd("upload-archive", ".", NULL);
 394        return -1;
 395}
 396
 397static int receive_pack(void)
 398{
 399        execl_git_cmd("receive-pack", ".", NULL);
 400        return -1;
 401}
 402
 403static struct daemon_service daemon_service[] = {
 404        { "upload-archive", "uploadarch", upload_archive, 0, 1 },
 405        { "upload-pack", "uploadpack", upload_pack, 1, 1 },
 406        { "receive-pack", "receivepack", receive_pack, 0, 1 },
 407};
 408
 409static void enable_service(const char *name, int ena)
 410{
 411        int i;
 412        for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 413                if (!strcmp(daemon_service[i].name, name)) {
 414                        daemon_service[i].enabled = ena;
 415                        return;
 416                }
 417        }
 418        die("No such service %s", name);
 419}
 420
 421static void make_service_overridable(const char *name, int ena)
 422{
 423        int i;
 424        for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 425                if (!strcmp(daemon_service[i].name, name)) {
 426                        daemon_service[i].overridable = ena;
 427                        return;
 428                }
 429        }
 430        die("No such service %s", name);
 431}
 432
 433/*
 434 * Separate the "extra args" information as supplied by the client connection.
 435 * Any resulting data is squirreled away in the given interpolation table.
 436 */
 437static void parse_extra_args(struct interp *table, char *extra_args, int buflen)
 438{
 439        char *val;
 440        int vallen;
 441        char *end = extra_args + buflen;
 442
 443        while (extra_args < end && *extra_args) {
 444                saw_extended_args = 1;
 445                if (strncasecmp("host=", extra_args, 5) == 0) {
 446                        val = extra_args + 5;
 447                        vallen = strlen(val) + 1;
 448                        if (*val) {
 449                                /* Split <host>:<port> at colon. */
 450                                char *host = val;
 451                                char *port = strrchr(host, ':');
 452                                if (port) {
 453                                        *port = 0;
 454                                        port++;
 455                                        interp_set_entry(table, INTERP_SLOT_PORT, port);
 456                                }
 457                                interp_set_entry(table, INTERP_SLOT_HOST, host);
 458                        }
 459
 460                        /* On to the next one */
 461                        extra_args = val + vallen;
 462                }
 463        }
 464}
 465
 466static void fill_in_extra_table_entries(struct interp *itable)
 467{
 468        char *hp;
 469
 470        /*
 471         * Replace literal host with lowercase-ized hostname.
 472         */
 473        hp = interp_table[INTERP_SLOT_HOST].value;
 474        if (!hp)
 475                return;
 476        for ( ; *hp; hp++)
 477                *hp = tolower(*hp);
 478
 479        /*
 480         * Locate canonical hostname and its IP address.
 481         */
 482#ifndef NO_IPV6
 483        {
 484                struct addrinfo hints;
 485                struct addrinfo *ai, *ai0;
 486                int gai;
 487                static char addrbuf[HOST_NAME_MAX + 1];
 488
 489                memset(&hints, 0, sizeof(hints));
 490                hints.ai_flags = AI_CANONNAME;
 491
 492                gai = getaddrinfo(interp_table[INTERP_SLOT_HOST].value, 0, &hints, &ai0);
 493                if (!gai) {
 494                        for (ai = ai0; ai; ai = ai->ai_next) {
 495                                struct sockaddr_in *sin_addr = (void *)ai->ai_addr;
 496
 497                                inet_ntop(AF_INET, &sin_addr->sin_addr,
 498                                          addrbuf, sizeof(addrbuf));
 499                                interp_set_entry(interp_table,
 500                                                 INTERP_SLOT_CANON_HOST, ai->ai_canonname);
 501                                interp_set_entry(interp_table,
 502                                                 INTERP_SLOT_IP, addrbuf);
 503                                break;
 504                        }
 505                        freeaddrinfo(ai0);
 506                }
 507        }
 508#else
 509        {
 510                struct hostent *hent;
 511                struct sockaddr_in sa;
 512                char **ap;
 513                static char addrbuf[HOST_NAME_MAX + 1];
 514
 515                hent = gethostbyname(interp_table[INTERP_SLOT_HOST].value);
 516
 517                ap = hent->h_addr_list;
 518                memset(&sa, 0, sizeof sa);
 519                sa.sin_family = hent->h_addrtype;
 520                sa.sin_port = htons(0);
 521                memcpy(&sa.sin_addr, *ap, hent->h_length);
 522
 523                inet_ntop(hent->h_addrtype, &sa.sin_addr,
 524                          addrbuf, sizeof(addrbuf));
 525
 526                interp_set_entry(interp_table, INTERP_SLOT_CANON_HOST, hent->h_name);
 527                interp_set_entry(interp_table, INTERP_SLOT_IP, addrbuf);
 528        }
 529#endif
 530}
 531
 532
 533static int execute(struct sockaddr *addr)
 534{
 535        static char line[1000];
 536        int pktlen, len, i;
 537
 538        if (addr) {
 539                char addrbuf[256] = "";
 540                int port = -1;
 541
 542                if (addr->sa_family == AF_INET) {
 543                        struct sockaddr_in *sin_addr = (void *) addr;
 544                        inet_ntop(addr->sa_family, &sin_addr->sin_addr, addrbuf, sizeof(addrbuf));
 545                        port = ntohs(sin_addr->sin_port);
 546#ifndef NO_IPV6
 547                } else if (addr && addr->sa_family == AF_INET6) {
 548                        struct sockaddr_in6 *sin6_addr = (void *) addr;
 549
 550                        char *buf = addrbuf;
 551                        *buf++ = '['; *buf = '\0'; /* stpcpy() is cool */
 552                        inet_ntop(AF_INET6, &sin6_addr->sin6_addr, buf, sizeof(addrbuf) - 1);
 553                        strcat(buf, "]");
 554
 555                        port = ntohs(sin6_addr->sin6_port);
 556#endif
 557                }
 558                loginfo("Connection from %s:%d", addrbuf, port);
 559        }
 560
 561        alarm(init_timeout ? init_timeout : timeout);
 562        pktlen = packet_read_line(0, line, sizeof(line));
 563        alarm(0);
 564
 565        len = strlen(line);
 566        if (pktlen != len)
 567                loginfo("Extended attributes (%d bytes) exist <%.*s>",
 568                        (int) pktlen - len,
 569                        (int) pktlen - len, line + len + 1);
 570        if (len && line[len-1] == '\n') {
 571                line[--len] = 0;
 572                pktlen--;
 573        }
 574
 575        /*
 576         * Initialize the path interpolation table for this connection.
 577         */
 578        interp_clear_table(interp_table, ARRAY_SIZE(interp_table));
 579        interp_set_entry(interp_table, INTERP_SLOT_PERCENT, "%");
 580
 581        if (len != pktlen) {
 582            parse_extra_args(interp_table, line + len + 1, pktlen - len - 1);
 583            fill_in_extra_table_entries(interp_table);
 584        }
 585
 586        for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 587                struct daemon_service *s = &(daemon_service[i]);
 588                int namelen = strlen(s->name);
 589                if (!prefixcmp(line, "git-") &&
 590                    !strncmp(s->name, line + 4, namelen) &&
 591                    line[namelen + 4] == ' ') {
 592                        /*
 593                         * Note: The directory here is probably context sensitive,
 594                         * and might depend on the actual service being performed.
 595                         */
 596                        interp_set_entry(interp_table,
 597                                         INTERP_SLOT_DIR, line + namelen + 5);
 598                        return run_service(interp_table, s);
 599                }
 600        }
 601
 602        logerror("Protocol error: '%s'", line);
 603        return -1;
 604}
 605
 606
 607/*
 608 * We count spawned/reaped separately, just to avoid any
 609 * races when updating them from signals. The SIGCHLD handler
 610 * will only update children_reaped, and the fork logic will
 611 * only update children_spawned.
 612 *
 613 * MAX_CHILDREN should be a power-of-two to make the modulus
 614 * operation cheap. It should also be at least twice
 615 * the maximum number of connections we will ever allow.
 616 */
 617#define MAX_CHILDREN 128
 618
 619static int max_connections = 25;
 620
 621/* These are updated by the signal handler */
 622static volatile unsigned int children_reaped;
 623static pid_t dead_child[MAX_CHILDREN];
 624
 625/* These are updated by the main loop */
 626static unsigned int children_spawned;
 627static unsigned int children_deleted;
 628
 629static struct child {
 630        pid_t pid;
 631        int addrlen;
 632        struct sockaddr_storage address;
 633} live_child[MAX_CHILDREN];
 634
 635static void add_child(int idx, pid_t pid, struct sockaddr *addr, int addrlen)
 636{
 637        live_child[idx].pid = pid;
 638        live_child[idx].addrlen = addrlen;
 639        memcpy(&live_child[idx].address, addr, addrlen);
 640}
 641
 642/*
 643 * Walk from "deleted" to "spawned", and remove child "pid".
 644 *
 645 * We move everything up by one, since the new "deleted" will
 646 * be one higher.
 647 */
 648static void remove_child(pid_t pid, unsigned deleted, unsigned spawned)
 649{
 650        struct child n;
 651
 652        deleted %= MAX_CHILDREN;
 653        spawned %= MAX_CHILDREN;
 654        if (live_child[deleted].pid == pid) {
 655                live_child[deleted].pid = -1;
 656                return;
 657        }
 658        n = live_child[deleted];
 659        for (;;) {
 660                struct child m;
 661                deleted = (deleted + 1) % MAX_CHILDREN;
 662                if (deleted == spawned)
 663                        die("could not find dead child %d\n", pid);
 664                m = live_child[deleted];
 665                live_child[deleted] = n;
 666                if (m.pid == pid)
 667                        return;
 668                n = m;
 669        }
 670}
 671
 672/*
 673 * This gets called if the number of connections grows
 674 * past "max_connections".
 675 *
 676 * We _should_ start off by searching for connections
 677 * from the same IP, and if there is some address wth
 678 * multiple connections, we should kill that first.
 679 *
 680 * As it is, we just "randomly" kill 25% of the connections,
 681 * and our pseudo-random generator sucks too. I have no
 682 * shame.
 683 *
 684 * Really, this is just a place-holder for a _real_ algorithm.
 685 */
 686static void kill_some_children(int signo, unsigned start, unsigned stop)
 687{
 688        start %= MAX_CHILDREN;
 689        stop %= MAX_CHILDREN;
 690        while (start != stop) {
 691                if (!(start & 3))
 692                        kill(live_child[start].pid, signo);
 693                start = (start + 1) % MAX_CHILDREN;
 694        }
 695}
 696
 697static void check_dead_children(void)
 698{
 699        unsigned spawned, reaped, deleted;
 700
 701        spawned = children_spawned;
 702        reaped = children_reaped;
 703        deleted = children_deleted;
 704
 705        while (deleted < reaped) {
 706                pid_t pid = dead_child[deleted % MAX_CHILDREN];
 707                const char *dead = pid < 0 ? " (with error)" : "";
 708
 709                if (pid < 0)
 710                        pid = -pid;
 711
 712                /* XXX: Custom logging, since we don't wanna getpid() */
 713                if (verbose) {
 714                        if (log_syslog)
 715                                syslog(LOG_INFO, "[%d] Disconnected%s",
 716                                                pid, dead);
 717                        else
 718                                fprintf(stderr, "[%d] Disconnected%s\n",
 719                                                pid, dead);
 720                }
 721                remove_child(pid, deleted, spawned);
 722                deleted++;
 723        }
 724        children_deleted = deleted;
 725}
 726
 727static void check_max_connections(void)
 728{
 729        for (;;) {
 730                int active;
 731                unsigned spawned, deleted;
 732
 733                check_dead_children();
 734
 735                spawned = children_spawned;
 736                deleted = children_deleted;
 737
 738                active = spawned - deleted;
 739                if (active <= max_connections)
 740                        break;
 741
 742                /* Kill some unstarted connections with SIGTERM */
 743                kill_some_children(SIGTERM, deleted, spawned);
 744                if (active <= max_connections << 1)
 745                        break;
 746
 747                /* If the SIGTERM thing isn't helping use SIGKILL */
 748                kill_some_children(SIGKILL, deleted, spawned);
 749                sleep(1);
 750        }
 751}
 752
 753static void handle(int incoming, struct sockaddr *addr, int addrlen)
 754{
 755        pid_t pid = fork();
 756
 757        if (pid) {
 758                unsigned idx;
 759
 760                close(incoming);
 761                if (pid < 0)
 762                        return;
 763
 764                idx = children_spawned % MAX_CHILDREN;
 765                children_spawned++;
 766                add_child(idx, pid, addr, addrlen);
 767
 768                check_max_connections();
 769                return;
 770        }
 771
 772        dup2(incoming, 0);
 773        dup2(incoming, 1);
 774        close(incoming);
 775
 776        exit(execute(addr));
 777}
 778
 779static void child_handler(int signo)
 780{
 781        for (;;) {
 782                int status;
 783                pid_t pid = waitpid(-1, &status, WNOHANG);
 784
 785                if (pid > 0) {
 786                        unsigned reaped = children_reaped;
 787                        if (!WIFEXITED(status) || WEXITSTATUS(status) > 0)
 788                                pid = -pid;
 789                        dead_child[reaped % MAX_CHILDREN] = pid;
 790                        children_reaped = reaped + 1;
 791                        continue;
 792                }
 793                break;
 794        }
 795}
 796
 797static int set_reuse_addr(int sockfd)
 798{
 799        int on = 1;
 800
 801        if (!reuseaddr)
 802                return 0;
 803        return setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
 804                          &on, sizeof(on));
 805}
 806
 807#ifndef NO_IPV6
 808
 809static int socksetup(char *listen_addr, int listen_port, int **socklist_p)
 810{
 811        int socknum = 0, *socklist = NULL;
 812        int maxfd = -1;
 813        char pbuf[NI_MAXSERV];
 814        struct addrinfo hints, *ai0, *ai;
 815        int gai;
 816        long flags;
 817
 818        sprintf(pbuf, "%d", listen_port);
 819        memset(&hints, 0, sizeof(hints));
 820        hints.ai_family = AF_UNSPEC;
 821        hints.ai_socktype = SOCK_STREAM;
 822        hints.ai_protocol = IPPROTO_TCP;
 823        hints.ai_flags = AI_PASSIVE;
 824
 825        gai = getaddrinfo(listen_addr, pbuf, &hints, &ai0);
 826        if (gai)
 827                die("getaddrinfo() failed: %s\n", gai_strerror(gai));
 828
 829        for (ai = ai0; ai; ai = ai->ai_next) {
 830                int sockfd;
 831
 832                sockfd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
 833                if (sockfd < 0)
 834                        continue;
 835                if (sockfd >= FD_SETSIZE) {
 836                        error("too large socket descriptor.");
 837                        close(sockfd);
 838                        continue;
 839                }
 840
 841#ifdef IPV6_V6ONLY
 842                if (ai->ai_family == AF_INET6) {
 843                        int on = 1;
 844                        setsockopt(sockfd, IPPROTO_IPV6, IPV6_V6ONLY,
 845                                   &on, sizeof(on));
 846                        /* Note: error is not fatal */
 847                }
 848#endif
 849
 850                if (set_reuse_addr(sockfd)) {
 851                        close(sockfd);
 852                        continue;
 853                }
 854
 855                if (bind(sockfd, ai->ai_addr, ai->ai_addrlen) < 0) {
 856                        close(sockfd);
 857                        continue;       /* not fatal */
 858                }
 859                if (listen(sockfd, 5) < 0) {
 860                        close(sockfd);
 861                        continue;       /* not fatal */
 862                }
 863
 864                flags = fcntl(sockfd, F_GETFD, 0);
 865                if (flags >= 0)
 866                        fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
 867
 868                socklist = xrealloc(socklist, sizeof(int) * (socknum + 1));
 869                socklist[socknum++] = sockfd;
 870
 871                if (maxfd < sockfd)
 872                        maxfd = sockfd;
 873        }
 874
 875        freeaddrinfo(ai0);
 876
 877        *socklist_p = socklist;
 878        return socknum;
 879}
 880
 881#else /* NO_IPV6 */
 882
 883static int socksetup(char *listen_addr, int listen_port, int **socklist_p)
 884{
 885        struct sockaddr_in sin;
 886        int sockfd;
 887        long flags;
 888
 889        memset(&sin, 0, sizeof sin);
 890        sin.sin_family = AF_INET;
 891        sin.sin_port = htons(listen_port);
 892
 893        if (listen_addr) {
 894                /* Well, host better be an IP address here. */
 895                if (inet_pton(AF_INET, listen_addr, &sin.sin_addr.s_addr) <= 0)
 896                        return 0;
 897        } else {
 898                sin.sin_addr.s_addr = htonl(INADDR_ANY);
 899        }
 900
 901        sockfd = socket(AF_INET, SOCK_STREAM, 0);
 902        if (sockfd < 0)
 903                return 0;
 904
 905        if (set_reuse_addr(sockfd)) {
 906                close(sockfd);
 907                return 0;
 908        }
 909
 910        if ( bind(sockfd, (struct sockaddr *)&sin, sizeof sin) < 0 ) {
 911                close(sockfd);
 912                return 0;
 913        }
 914
 915        if (listen(sockfd, 5) < 0) {
 916                close(sockfd);
 917                return 0;
 918        }
 919
 920        flags = fcntl(sockfd, F_GETFD, 0);
 921        if (flags >= 0)
 922                fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
 923
 924        *socklist_p = xmalloc(sizeof(int));
 925        **socklist_p = sockfd;
 926        return 1;
 927}
 928
 929#endif
 930
 931static int service_loop(int socknum, int *socklist)
 932{
 933        struct pollfd *pfd;
 934        int i;
 935
 936        pfd = xcalloc(socknum, sizeof(struct pollfd));
 937
 938        for (i = 0; i < socknum; i++) {
 939                pfd[i].fd = socklist[i];
 940                pfd[i].events = POLLIN;
 941        }
 942
 943        signal(SIGCHLD, child_handler);
 944
 945        for (;;) {
 946                int i;
 947                int timeout;
 948
 949                /*
 950                 * This 1-sec timeout could lead to idly looping but it is
 951                 * here so that children culled in child_handler() are reported
 952                 * without too much delay.  We could probably set up a pipe
 953                 * to ourselves that we poll, and write to the fd from child_handler()
 954                 * to wake us up (and consume it when the poll() returns...
 955                 */
 956                timeout = (children_spawned != children_deleted) ? 1000 : -1;
 957                i = poll(pfd, socknum, timeout);
 958                if (i < 0) {
 959                        if (errno != EINTR) {
 960                                error("poll failed, resuming: %s",
 961                                      strerror(errno));
 962                                sleep(1);
 963                        }
 964                        continue;
 965                }
 966                if (i == 0) {
 967                        check_dead_children();
 968                        continue;
 969                }
 970
 971                for (i = 0; i < socknum; i++) {
 972                        if (pfd[i].revents & POLLIN) {
 973                                struct sockaddr_storage ss;
 974                                unsigned int sslen = sizeof(ss);
 975                                int incoming = accept(pfd[i].fd, (struct sockaddr *)&ss, &sslen);
 976                                if (incoming < 0) {
 977                                        switch (errno) {
 978                                        case EAGAIN:
 979                                        case EINTR:
 980                                        case ECONNABORTED:
 981                                                continue;
 982                                        default:
 983                                                die("accept returned %s", strerror(errno));
 984                                        }
 985                                }
 986                                handle(incoming, (struct sockaddr *)&ss, sslen);
 987                        }
 988                }
 989        }
 990}
 991
 992/* if any standard file descriptor is missing open it to /dev/null */
 993static void sanitize_stdfds(void)
 994{
 995        int fd = open("/dev/null", O_RDWR, 0);
 996        while (fd != -1 && fd < 2)
 997                fd = dup(fd);
 998        if (fd == -1)
 999                die("open /dev/null or dup failed: %s", strerror(errno));
1000        if (fd > 2)
1001                close(fd);
1002}
1003
1004static void daemonize(void)
1005{
1006        switch (fork()) {
1007                case 0:
1008                        break;
1009                case -1:
1010                        die("fork failed: %s", strerror(errno));
1011                default:
1012                        exit(0);
1013        }
1014        if (setsid() == -1)
1015                die("setsid failed: %s", strerror(errno));
1016        close(0);
1017        close(1);
1018        close(2);
1019        sanitize_stdfds();
1020}
1021
1022static void store_pid(const char *path)
1023{
1024        FILE *f = fopen(path, "w");
1025        if (!f)
1026                die("cannot open pid file %s: %s", path, strerror(errno));
1027        if (fprintf(f, "%d\n", getpid()) < 0 || fclose(f) != 0)
1028                die("failed to write pid file %s: %s", path, strerror(errno));
1029}
1030
1031static int serve(char *listen_addr, int listen_port, struct passwd *pass, gid_t gid)
1032{
1033        int socknum, *socklist;
1034
1035        socknum = socksetup(listen_addr, listen_port, &socklist);
1036        if (socknum == 0)
1037                die("unable to allocate any listen sockets on host %s port %u",
1038                    listen_addr, listen_port);
1039
1040        if (pass && gid &&
1041            (initgroups(pass->pw_name, gid) || setgid (gid) ||
1042             setuid(pass->pw_uid)))
1043                die("cannot drop privileges");
1044
1045        return service_loop(socknum, socklist);
1046}
1047
1048int main(int argc, char **argv)
1049{
1050        int listen_port = 0;
1051        char *listen_addr = NULL;
1052        int inetd_mode = 0;
1053        const char *pid_file = NULL, *user_name = NULL, *group_name = NULL;
1054        int detach = 0;
1055        struct passwd *pass = NULL;
1056        struct group *group;
1057        gid_t gid = 0;
1058        int i;
1059
1060        /* Without this we cannot rely on waitpid() to tell
1061         * what happened to our children.
1062         */
1063        signal(SIGCHLD, SIG_DFL);
1064
1065        for (i = 1; i < argc; i++) {
1066                char *arg = argv[i];
1067
1068                if (!prefixcmp(arg, "--listen=")) {
1069                    char *p = arg + 9;
1070                    char *ph = listen_addr = xmalloc(strlen(arg + 9) + 1);
1071                    while (*p)
1072                        *ph++ = tolower(*p++);
1073                    *ph = 0;
1074                    continue;
1075                }
1076                if (!prefixcmp(arg, "--port=")) {
1077                        char *end;
1078                        unsigned long n;
1079                        n = strtoul(arg+7, &end, 0);
1080                        if (arg[7] && !*end) {
1081                                listen_port = n;
1082                                continue;
1083                        }
1084                }
1085                if (!strcmp(arg, "--inetd")) {
1086                        inetd_mode = 1;
1087                        log_syslog = 1;
1088                        continue;
1089                }
1090                if (!strcmp(arg, "--verbose")) {
1091                        verbose = 1;
1092                        continue;
1093                }
1094                if (!strcmp(arg, "--syslog")) {
1095                        log_syslog = 1;
1096                        continue;
1097                }
1098                if (!strcmp(arg, "--export-all")) {
1099                        export_all_trees = 1;
1100                        continue;
1101                }
1102                if (!prefixcmp(arg, "--timeout=")) {
1103                        timeout = atoi(arg+10);
1104                        continue;
1105                }
1106                if (!prefixcmp(arg, "--init-timeout=")) {
1107                        init_timeout = atoi(arg+15);
1108                        continue;
1109                }
1110                if (!strcmp(arg, "--strict-paths")) {
1111                        strict_paths = 1;
1112                        continue;
1113                }
1114                if (!prefixcmp(arg, "--base-path=")) {
1115                        base_path = arg+12;
1116                        continue;
1117                }
1118                if (!strcmp(arg, "--base-path-relaxed")) {
1119                        base_path_relaxed = 1;
1120                        continue;
1121                }
1122                if (!prefixcmp(arg, "--interpolated-path=")) {
1123                        interpolated_path = arg+20;
1124                        continue;
1125                }
1126                if (!strcmp(arg, "--reuseaddr")) {
1127                        reuseaddr = 1;
1128                        continue;
1129                }
1130                if (!strcmp(arg, "--user-path")) {
1131                        user_path = "";
1132                        continue;
1133                }
1134                if (!prefixcmp(arg, "--user-path=")) {
1135                        user_path = arg + 12;
1136                        continue;
1137                }
1138                if (!prefixcmp(arg, "--pid-file=")) {
1139                        pid_file = arg + 11;
1140                        continue;
1141                }
1142                if (!strcmp(arg, "--detach")) {
1143                        detach = 1;
1144                        log_syslog = 1;
1145                        continue;
1146                }
1147                if (!prefixcmp(arg, "--user=")) {
1148                        user_name = arg + 7;
1149                        continue;
1150                }
1151                if (!prefixcmp(arg, "--group=")) {
1152                        group_name = arg + 8;
1153                        continue;
1154                }
1155                if (!prefixcmp(arg, "--enable=")) {
1156                        enable_service(arg + 9, 1);
1157                        continue;
1158                }
1159                if (!prefixcmp(arg, "--disable=")) {
1160                        enable_service(arg + 10, 0);
1161                        continue;
1162                }
1163                if (!prefixcmp(arg, "--allow-override=")) {
1164                        make_service_overridable(arg + 17, 1);
1165                        continue;
1166                }
1167                if (!prefixcmp(arg, "--forbid-override=")) {
1168                        make_service_overridable(arg + 18, 0);
1169                        continue;
1170                }
1171                if (!strcmp(arg, "--")) {
1172                        ok_paths = &argv[i+1];
1173                        break;
1174                } else if (arg[0] != '-') {
1175                        ok_paths = &argv[i];
1176                        break;
1177                }
1178
1179                usage(daemon_usage);
1180        }
1181
1182        if (log_syslog) {
1183                openlog("git-daemon", 0, LOG_DAEMON);
1184                set_die_routine(daemon_die);
1185        }
1186
1187        if (inetd_mode && (group_name || user_name))
1188                die("--user and --group are incompatible with --inetd");
1189
1190        if (inetd_mode && (listen_port || listen_addr))
1191                die("--listen= and --port= are incompatible with --inetd");
1192        else if (listen_port == 0)
1193                listen_port = DEFAULT_GIT_PORT;
1194
1195        if (group_name && !user_name)
1196                die("--group supplied without --user");
1197
1198        if (user_name) {
1199                pass = getpwnam(user_name);
1200                if (!pass)
1201                        die("user not found - %s", user_name);
1202
1203                if (!group_name)
1204                        gid = pass->pw_gid;
1205                else {
1206                        group = getgrnam(group_name);
1207                        if (!group)
1208                                die("group not found - %s", group_name);
1209
1210                        gid = group->gr_gid;
1211                }
1212        }
1213
1214        if (strict_paths && (!ok_paths || !*ok_paths))
1215                die("option --strict-paths requires a whitelist");
1216
1217        if (base_path) {
1218                struct stat st;
1219
1220                if (stat(base_path, &st) || !S_ISDIR(st.st_mode))
1221                        die("base-path '%s' does not exist or "
1222                            "is not a directory", base_path);
1223        }
1224
1225        if (inetd_mode) {
1226                struct sockaddr_storage ss;
1227                struct sockaddr *peer = (struct sockaddr *)&ss;
1228                socklen_t slen = sizeof(ss);
1229
1230                freopen("/dev/null", "w", stderr);
1231
1232                if (getpeername(0, peer, &slen))
1233                        peer = NULL;
1234
1235                return execute(peer);
1236        }
1237
1238        if (detach)
1239                daemonize();
1240        else
1241                sanitize_stdfds();
1242
1243        if (pid_file)
1244                store_pid(pid_file);
1245
1246        return serve(listen_addr, listen_port, pass, gid);
1247}