Andrew's git / gitweb.git / daemon.c
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daemon.con commit daemon: detect and reject too-long paths (6bdb008)
   1#include "cache.h"
   2#include "pkt-line.h"
   3#include "exec_cmd.h"
   4#include "run-command.h"
   5#include "strbuf.h"
   6#include "string-list.h"
   7
   8#ifndef HOST_NAME_MAX
   9#define HOST_NAME_MAX 256
  10#endif
  11
  12#ifdef NO_INITGROUPS
  13#define initgroups(x, y) (0) /* nothing */
  14#endif
  15
  16static int log_syslog;
  17static int verbose;
  18static int reuseaddr;
  19static int informative_errors;
  20
  21static const char daemon_usage[] =
  22"git daemon [--verbose] [--syslog] [--export-all]\n"
  23"           [--timeout=<n>] [--init-timeout=<n>] [--max-connections=<n>]\n"
  24"           [--strict-paths] [--base-path=<path>] [--base-path-relaxed]\n"
  25"           [--user-path | --user-path=<path>]\n"
  26"           [--interpolated-path=<path>]\n"
  27"           [--reuseaddr] [--pid-file=<file>]\n"
  28"           [--(enable|disable|allow-override|forbid-override)=<service>]\n"
  29"           [--access-hook=<path>]\n"
  30"           [--inetd | [--listen=<host_or_ipaddr>] [--port=<n>]\n"
  31"                      [--detach] [--user=<user> [--group=<group>]]\n"
  32"           [<directory>...]";
  33
  34/* List of acceptable pathname prefixes */
  35static char **ok_paths;
  36static int strict_paths;
  37
  38/* If this is set, git-daemon-export-ok is not required */
  39static int export_all_trees;
  40
  41/* Take all paths relative to this one if non-NULL */
  42static const char *base_path;
  43static const char *interpolated_path;
  44static int base_path_relaxed;
  45
  46/* If defined, ~user notation is allowed and the string is inserted
  47 * after ~user/.  E.g. a request to git://host/~alice/frotz would
  48 * go to /home/alice/pub_git/frotz with --user-path=pub_git.
  49 */
  50static const char *user_path;
  51
  52/* Timeout, and initial timeout */
  53static unsigned int timeout;
  54static unsigned int init_timeout;
  55
  56struct hostinfo {
  57        struct strbuf hostname;
  58        struct strbuf canon_hostname;
  59        struct strbuf ip_address;
  60        struct strbuf tcp_port;
  61        unsigned int hostname_lookup_done:1;
  62        unsigned int saw_extended_args:1;
  63};
  64
  65static void lookup_hostname(struct hostinfo *hi);
  66
  67static const char *get_canon_hostname(struct hostinfo *hi)
  68{
  69        lookup_hostname(hi);
  70        return hi->canon_hostname.buf;
  71}
  72
  73static const char *get_ip_address(struct hostinfo *hi)
  74{
  75        lookup_hostname(hi);
  76        return hi->ip_address.buf;
  77}
  78
  79static void logreport(int priority, const char *err, va_list params)
  80{
  81        if (log_syslog) {
  82                char buf[1024];
  83                vsnprintf(buf, sizeof(buf), err, params);
  84                syslog(priority, "%s", buf);
  85        } else {
  86                /*
  87                 * Since stderr is set to buffered mode, the
  88                 * logging of different processes will not overlap
  89                 * unless they overflow the (rather big) buffers.
  90                 */
  91                fprintf(stderr, "[%"PRIuMAX"] ", (uintmax_t)getpid());
  92                vfprintf(stderr, err, params);
  93                fputc('\n', stderr);
  94                fflush(stderr);
  95        }
  96}
  97
  98__attribute__((format (printf, 1, 2)))
  99static void logerror(const char *err, ...)
 100{
 101        va_list params;
 102        va_start(params, err);
 103        logreport(LOG_ERR, err, params);
 104        va_end(params);
 105}
 106
 107__attribute__((format (printf, 1, 2)))
 108static void loginfo(const char *err, ...)
 109{
 110        va_list params;
 111        if (!verbose)
 112                return;
 113        va_start(params, err);
 114        logreport(LOG_INFO, err, params);
 115        va_end(params);
 116}
 117
 118static void NORETURN daemon_die(const char *err, va_list params)
 119{
 120        logreport(LOG_ERR, err, params);
 121        exit(1);
 122}
 123
 124struct expand_path_context {
 125        const char *directory;
 126        struct hostinfo *hostinfo;
 127};
 128
 129static size_t expand_path(struct strbuf *sb, const char *placeholder, void *ctx)
 130{
 131        struct expand_path_context *context = ctx;
 132        struct hostinfo *hi = context->hostinfo;
 133
 134        switch (placeholder[0]) {
 135        case 'H':
 136                strbuf_addbuf(sb, &hi->hostname);
 137                return 1;
 138        case 'C':
 139                if (placeholder[1] == 'H') {
 140                        strbuf_addstr(sb, get_canon_hostname(hi));
 141                        return 2;
 142                }
 143                break;
 144        case 'I':
 145                if (placeholder[1] == 'P') {
 146                        strbuf_addstr(sb, get_ip_address(hi));
 147                        return 2;
 148                }
 149                break;
 150        case 'P':
 151                strbuf_addbuf(sb, &hi->tcp_port);
 152                return 1;
 153        case 'D':
 154                strbuf_addstr(sb, context->directory);
 155                return 1;
 156        }
 157        return 0;
 158}
 159
 160static const char *path_ok(const char *directory, struct hostinfo *hi)
 161{
 162        static char rpath[PATH_MAX];
 163        static char interp_path[PATH_MAX];
 164        size_t rlen;
 165        const char *path;
 166        const char *dir;
 167
 168        dir = directory;
 169
 170        if (daemon_avoid_alias(dir)) {
 171                logerror("'%s': aliased", dir);
 172                return NULL;
 173        }
 174
 175        if (*dir == '~') {
 176                if (!user_path) {
 177                        logerror("'%s': User-path not allowed", dir);
 178                        return NULL;
 179                }
 180                if (*user_path) {
 181                        /* Got either "~alice" or "~alice/foo";
 182                         * rewrite them to "~alice/%s" or
 183                         * "~alice/%s/foo".
 184                         */
 185                        int namlen, restlen = strlen(dir);
 186                        const char *slash = strchr(dir, '/');
 187                        if (!slash)
 188                                slash = dir + restlen;
 189                        namlen = slash - dir;
 190                        restlen -= namlen;
 191                        loginfo("userpath <%s>, request <%s>, namlen %d, restlen %d, slash <%s>", user_path, dir, namlen, restlen, slash);
 192                        rlen = snprintf(rpath, sizeof(rpath), "%.*s/%s%.*s",
 193                                        namlen, dir, user_path, restlen, slash);
 194                        if (rlen >= sizeof(rpath)) {
 195                                logerror("user-path too large: %s", rpath);
 196                                return NULL;
 197                        }
 198                        dir = rpath;
 199                }
 200        }
 201        else if (interpolated_path && hi->saw_extended_args) {
 202                struct strbuf expanded_path = STRBUF_INIT;
 203                struct expand_path_context context;
 204
 205                context.directory = directory;
 206                context.hostinfo = hi;
 207
 208                if (*dir != '/') {
 209                        /* Allow only absolute */
 210                        logerror("'%s': Non-absolute path denied (interpolated-path active)", dir);
 211                        return NULL;
 212                }
 213
 214                strbuf_expand(&expanded_path, interpolated_path,
 215                              expand_path, &context);
 216
 217                rlen = strlcpy(interp_path, expanded_path.buf,
 218                               sizeof(interp_path));
 219                if (rlen >= sizeof(interp_path)) {
 220                        logerror("interpolated path too large: %s",
 221                                 interp_path);
 222                        return NULL;
 223                }
 224
 225                strbuf_release(&expanded_path);
 226                loginfo("Interpolated dir '%s'", interp_path);
 227
 228                dir = interp_path;
 229        }
 230        else if (base_path) {
 231                if (*dir != '/') {
 232                        /* Allow only absolute */
 233                        logerror("'%s': Non-absolute path denied (base-path active)", dir);
 234                        return NULL;
 235                }
 236                rlen = snprintf(rpath, sizeof(rpath), "%s%s", base_path, dir);
 237                if (rlen >= sizeof(rpath)) {
 238                        logerror("base-path too large: %s", rpath);
 239                        return NULL;
 240                }
 241                dir = rpath;
 242        }
 243
 244        path = enter_repo(dir, strict_paths);
 245        if (!path && base_path && base_path_relaxed) {
 246                /*
 247                 * if we fail and base_path_relaxed is enabled, try without
 248                 * prefixing the base path
 249                 */
 250                dir = directory;
 251                path = enter_repo(dir, strict_paths);
 252        }
 253
 254        if (!path) {
 255                logerror("'%s' does not appear to be a git repository", dir);
 256                return NULL;
 257        }
 258
 259        if ( ok_paths && *ok_paths ) {
 260                char **pp;
 261                int pathlen = strlen(path);
 262
 263                /* The validation is done on the paths after enter_repo
 264                 * appends optional {.git,.git/.git} and friends, but
 265                 * it does not use getcwd().  So if your /pub is
 266                 * a symlink to /mnt/pub, you can whitelist /pub and
 267                 * do not have to say /mnt/pub.
 268                 * Do not say /pub/.
 269                 */
 270                for ( pp = ok_paths ; *pp ; pp++ ) {
 271                        int len = strlen(*pp);
 272                        if (len <= pathlen &&
 273                            !memcmp(*pp, path, len) &&
 274                            (path[len] == '\0' ||
 275                             (!strict_paths && path[len] == '/')))
 276                                return path;
 277                }
 278        }
 279        else {
 280                /* be backwards compatible */
 281                if (!strict_paths)
 282                        return path;
 283        }
 284
 285        logerror("'%s': not in whitelist", path);
 286        return NULL;            /* Fallthrough. Deny by default */
 287}
 288
 289typedef int (*daemon_service_fn)(void);
 290struct daemon_service {
 291        const char *name;
 292        const char *config_name;
 293        daemon_service_fn fn;
 294        int enabled;
 295        int overridable;
 296};
 297
 298static int daemon_error(const char *dir, const char *msg)
 299{
 300        if (!informative_errors)
 301                msg = "access denied or repository not exported";
 302        packet_write(1, "ERR %s: %s", msg, dir);
 303        return -1;
 304}
 305
 306static const char *access_hook;
 307
 308static int run_access_hook(struct daemon_service *service, const char *dir,
 309                           const char *path, struct hostinfo *hi)
 310{
 311        struct child_process child = CHILD_PROCESS_INIT;
 312        struct strbuf buf = STRBUF_INIT;
 313        const char *argv[8];
 314        const char **arg = argv;
 315        char *eol;
 316        int seen_errors = 0;
 317
 318        *arg++ = access_hook;
 319        *arg++ = service->name;
 320        *arg++ = path;
 321        *arg++ = hi->hostname.buf;
 322        *arg++ = get_canon_hostname(hi);
 323        *arg++ = get_ip_address(hi);
 324        *arg++ = hi->tcp_port.buf;
 325        *arg = NULL;
 326
 327        child.use_shell = 1;
 328        child.argv = argv;
 329        child.no_stdin = 1;
 330        child.no_stderr = 1;
 331        child.out = -1;
 332        if (start_command(&child)) {
 333                logerror("daemon access hook '%s' failed to start",
 334                         access_hook);
 335                goto error_return;
 336        }
 337        if (strbuf_read(&buf, child.out, 0) < 0) {
 338                logerror("failed to read from pipe to daemon access hook '%s'",
 339                         access_hook);
 340                strbuf_reset(&buf);
 341                seen_errors = 1;
 342        }
 343        if (close(child.out) < 0) {
 344                logerror("failed to close pipe to daemon access hook '%s'",
 345                         access_hook);
 346                seen_errors = 1;
 347        }
 348        if (finish_command(&child))
 349                seen_errors = 1;
 350
 351        if (!seen_errors) {
 352                strbuf_release(&buf);
 353                return 0;
 354        }
 355
 356error_return:
 357        strbuf_ltrim(&buf);
 358        if (!buf.len)
 359                strbuf_addstr(&buf, "service rejected");
 360        eol = strchr(buf.buf, '\n');
 361        if (eol)
 362                *eol = '\0';
 363        errno = EACCES;
 364        daemon_error(dir, buf.buf);
 365        strbuf_release(&buf);
 366        return -1;
 367}
 368
 369static int run_service(const char *dir, struct daemon_service *service,
 370                       struct hostinfo *hi)
 371{
 372        const char *path;
 373        int enabled = service->enabled;
 374        struct strbuf var = STRBUF_INIT;
 375
 376        loginfo("Request %s for '%s'", service->name, dir);
 377
 378        if (!enabled && !service->overridable) {
 379                logerror("'%s': service not enabled.", service->name);
 380                errno = EACCES;
 381                return daemon_error(dir, "service not enabled");
 382        }
 383
 384        if (!(path = path_ok(dir, hi)))
 385                return daemon_error(dir, "no such repository");
 386
 387        /*
 388         * Security on the cheap.
 389         *
 390         * We want a readable HEAD, usable "objects" directory, and
 391         * a "git-daemon-export-ok" flag that says that the other side
 392         * is ok with us doing this.
 393         *
 394         * path_ok() uses enter_repo() and does whitelist checking.
 395         * We only need to make sure the repository is exported.
 396         */
 397
 398        if (!export_all_trees && access("git-daemon-export-ok", F_OK)) {
 399                logerror("'%s': repository not exported.", path);
 400                errno = EACCES;
 401                return daemon_error(dir, "repository not exported");
 402        }
 403
 404        if (service->overridable) {
 405                strbuf_addf(&var, "daemon.%s", service->config_name);
 406                git_config_get_bool(var.buf, &enabled);
 407                strbuf_release(&var);
 408        }
 409        if (!enabled) {
 410                logerror("'%s': service not enabled for '%s'",
 411                         service->name, path);
 412                errno = EACCES;
 413                return daemon_error(dir, "service not enabled");
 414        }
 415
 416        /*
 417         * Optionally, a hook can choose to deny access to the
 418         * repository depending on the phase of the moon.
 419         */
 420        if (access_hook && run_access_hook(service, dir, path, hi))
 421                return -1;
 422
 423        /*
 424         * We'll ignore SIGTERM from now on, we have a
 425         * good client.
 426         */
 427        signal(SIGTERM, SIG_IGN);
 428
 429        return service->fn();
 430}
 431
 432static void copy_to_log(int fd)
 433{
 434        struct strbuf line = STRBUF_INIT;
 435        FILE *fp;
 436
 437        fp = fdopen(fd, "r");
 438        if (fp == NULL) {
 439                logerror("fdopen of error channel failed");
 440                close(fd);
 441                return;
 442        }
 443
 444        while (strbuf_getline_lf(&line, fp) != EOF) {
 445                logerror("%s", line.buf);
 446                strbuf_setlen(&line, 0);
 447        }
 448
 449        strbuf_release(&line);
 450        fclose(fp);
 451}
 452
 453static int run_service_command(const char **argv)
 454{
 455        struct child_process cld = CHILD_PROCESS_INIT;
 456
 457        cld.argv = argv;
 458        cld.git_cmd = 1;
 459        cld.err = -1;
 460        if (start_command(&cld))
 461                return -1;
 462
 463        close(0);
 464        close(1);
 465
 466        copy_to_log(cld.err);
 467
 468        return finish_command(&cld);
 469}
 470
 471static int upload_pack(void)
 472{
 473        /* Timeout as string */
 474        char timeout_buf[64];
 475        const char *argv[] = { "upload-pack", "--strict", NULL, ".", NULL };
 476
 477        argv[2] = timeout_buf;
 478
 479        snprintf(timeout_buf, sizeof timeout_buf, "--timeout=%u", timeout);
 480        return run_service_command(argv);
 481}
 482
 483static int upload_archive(void)
 484{
 485        static const char *argv[] = { "upload-archive", ".", NULL };
 486        return run_service_command(argv);
 487}
 488
 489static int receive_pack(void)
 490{
 491        static const char *argv[] = { "receive-pack", ".", NULL };
 492        return run_service_command(argv);
 493}
 494
 495static struct daemon_service daemon_service[] = {
 496        { "upload-archive", "uploadarch", upload_archive, 0, 1 },
 497        { "upload-pack", "uploadpack", upload_pack, 1, 1 },
 498        { "receive-pack", "receivepack", receive_pack, 0, 1 },
 499};
 500
 501static void enable_service(const char *name, int ena)
 502{
 503        int i;
 504        for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 505                if (!strcmp(daemon_service[i].name, name)) {
 506                        daemon_service[i].enabled = ena;
 507                        return;
 508                }
 509        }
 510        die("No such service %s", name);
 511}
 512
 513static void make_service_overridable(const char *name, int ena)
 514{
 515        int i;
 516        for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 517                if (!strcmp(daemon_service[i].name, name)) {
 518                        daemon_service[i].overridable = ena;
 519                        return;
 520                }
 521        }
 522        die("No such service %s", name);
 523}
 524
 525static void parse_host_and_port(char *hostport, char **host,
 526        char **port)
 527{
 528        if (*hostport == '[') {
 529                char *end;
 530
 531                end = strchr(hostport, ']');
 532                if (!end)
 533                        die("Invalid request ('[' without ']')");
 534                *end = '\0';
 535                *host = hostport + 1;
 536                if (!end[1])
 537                        *port = NULL;
 538                else if (end[1] == ':')
 539                        *port = end + 2;
 540                else
 541                        die("Garbage after end of host part");
 542        } else {
 543                *host = hostport;
 544                *port = strrchr(hostport, ':');
 545                if (*port) {
 546                        **port = '\0';
 547                        ++*port;
 548                }
 549        }
 550}
 551
 552/*
 553 * Sanitize a string from the client so that it's OK to be inserted into a
 554 * filesystem path. Specifically, we disallow slashes, runs of "..", and
 555 * trailing and leading dots, which means that the client cannot escape
 556 * our base path via ".." traversal.
 557 */
 558static void sanitize_client(struct strbuf *out, const char *in)
 559{
 560        for (; *in; in++) {
 561                if (*in == '/')
 562                        continue;
 563                if (*in == '.' && (!out->len || out->buf[out->len - 1] == '.'))
 564                        continue;
 565                strbuf_addch(out, *in);
 566        }
 567
 568        while (out->len && out->buf[out->len - 1] == '.')
 569                strbuf_setlen(out, out->len - 1);
 570}
 571
 572/*
 573 * Like sanitize_client, but we also perform any canonicalization
 574 * to make life easier on the admin.
 575 */
 576static void canonicalize_client(struct strbuf *out, const char *in)
 577{
 578        sanitize_client(out, in);
 579        strbuf_tolower(out);
 580}
 581
 582/*
 583 * Read the host as supplied by the client connection.
 584 */
 585static void parse_host_arg(struct hostinfo *hi, char *extra_args, int buflen)
 586{
 587        char *val;
 588        int vallen;
 589        char *end = extra_args + buflen;
 590
 591        if (extra_args < end && *extra_args) {
 592                hi->saw_extended_args = 1;
 593                if (strncasecmp("host=", extra_args, 5) == 0) {
 594                        val = extra_args + 5;
 595                        vallen = strlen(val) + 1;
 596                        if (*val) {
 597                                /* Split <host>:<port> at colon. */
 598                                char *host;
 599                                char *port;
 600                                parse_host_and_port(val, &host, &port);
 601                                if (port)
 602                                        sanitize_client(&hi->tcp_port, port);
 603                                canonicalize_client(&hi->hostname, host);
 604                                hi->hostname_lookup_done = 0;
 605                        }
 606
 607                        /* On to the next one */
 608                        extra_args = val + vallen;
 609                }
 610                if (extra_args < end && *extra_args)
 611                        die("Invalid request");
 612        }
 613}
 614
 615/*
 616 * Locate canonical hostname and its IP address.
 617 */
 618static void lookup_hostname(struct hostinfo *hi)
 619{
 620        if (!hi->hostname_lookup_done && hi->hostname.len) {
 621#ifndef NO_IPV6
 622                struct addrinfo hints;
 623                struct addrinfo *ai;
 624                int gai;
 625                static char addrbuf[HOST_NAME_MAX + 1];
 626
 627                memset(&hints, 0, sizeof(hints));
 628                hints.ai_flags = AI_CANONNAME;
 629
 630                gai = getaddrinfo(hi->hostname.buf, NULL, &hints, &ai);
 631                if (!gai) {
 632                        struct sockaddr_in *sin_addr = (void *)ai->ai_addr;
 633
 634                        inet_ntop(AF_INET, &sin_addr->sin_addr,
 635                                  addrbuf, sizeof(addrbuf));
 636                        strbuf_addstr(&hi->ip_address, addrbuf);
 637
 638                        if (ai->ai_canonname)
 639                                sanitize_client(&hi->canon_hostname,
 640                                                ai->ai_canonname);
 641                        else
 642                                strbuf_addbuf(&hi->canon_hostname,
 643                                              &hi->ip_address);
 644
 645                        freeaddrinfo(ai);
 646                }
 647#else
 648                struct hostent *hent;
 649                struct sockaddr_in sa;
 650                char **ap;
 651                static char addrbuf[HOST_NAME_MAX + 1];
 652
 653                hent = gethostbyname(hi->hostname.buf);
 654                if (hent) {
 655                        ap = hent->h_addr_list;
 656                        memset(&sa, 0, sizeof sa);
 657                        sa.sin_family = hent->h_addrtype;
 658                        sa.sin_port = htons(0);
 659                        memcpy(&sa.sin_addr, *ap, hent->h_length);
 660
 661                        inet_ntop(hent->h_addrtype, &sa.sin_addr,
 662                                  addrbuf, sizeof(addrbuf));
 663
 664                        sanitize_client(&hi->canon_hostname, hent->h_name);
 665                        strbuf_addstr(&hi->ip_address, addrbuf);
 666                }
 667#endif
 668                hi->hostname_lookup_done = 1;
 669        }
 670}
 671
 672static void hostinfo_init(struct hostinfo *hi)
 673{
 674        memset(hi, 0, sizeof(*hi));
 675        strbuf_init(&hi->hostname, 0);
 676        strbuf_init(&hi->canon_hostname, 0);
 677        strbuf_init(&hi->ip_address, 0);
 678        strbuf_init(&hi->tcp_port, 0);
 679}
 680
 681static void hostinfo_clear(struct hostinfo *hi)
 682{
 683        strbuf_release(&hi->hostname);
 684        strbuf_release(&hi->canon_hostname);
 685        strbuf_release(&hi->ip_address);
 686        strbuf_release(&hi->tcp_port);
 687}
 688
 689static int execute(void)
 690{
 691        char *line = packet_buffer;
 692        int pktlen, len, i;
 693        char *addr = getenv("REMOTE_ADDR"), *port = getenv("REMOTE_PORT");
 694        struct hostinfo hi;
 695
 696        hostinfo_init(&hi);
 697
 698        if (addr)
 699                loginfo("Connection from %s:%s", addr, port);
 700
 701        alarm(init_timeout ? init_timeout : timeout);
 702        pktlen = packet_read(0, NULL, NULL, packet_buffer, sizeof(packet_buffer), 0);
 703        alarm(0);
 704
 705        len = strlen(line);
 706        if (pktlen != len)
 707                loginfo("Extended attributes (%d bytes) exist <%.*s>",
 708                        (int) pktlen - len,
 709                        (int) pktlen - len, line + len + 1);
 710        if (len && line[len-1] == '\n') {
 711                line[--len] = 0;
 712                pktlen--;
 713        }
 714
 715        if (len != pktlen)
 716                parse_host_arg(&hi, line + len + 1, pktlen - len - 1);
 717
 718        for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 719                struct daemon_service *s = &(daemon_service[i]);
 720                const char *arg;
 721
 722                if (skip_prefix(line, "git-", &arg) &&
 723                    skip_prefix(arg, s->name, &arg) &&
 724                    *arg++ == ' ') {
 725                        /*
 726                         * Note: The directory here is probably context sensitive,
 727                         * and might depend on the actual service being performed.
 728                         */
 729                        int rc = run_service(arg, s, &hi);
 730                        hostinfo_clear(&hi);
 731                        return rc;
 732                }
 733        }
 734
 735        hostinfo_clear(&hi);
 736        logerror("Protocol error: '%s'", line);
 737        return -1;
 738}
 739
 740static int addrcmp(const struct sockaddr_storage *s1,
 741    const struct sockaddr_storage *s2)
 742{
 743        const struct sockaddr *sa1 = (const struct sockaddr*) s1;
 744        const struct sockaddr *sa2 = (const struct sockaddr*) s2;
 745
 746        if (sa1->sa_family != sa2->sa_family)
 747                return sa1->sa_family - sa2->sa_family;
 748        if (sa1->sa_family == AF_INET)
 749                return memcmp(&((struct sockaddr_in *)s1)->sin_addr,
 750                    &((struct sockaddr_in *)s2)->sin_addr,
 751                    sizeof(struct in_addr));
 752#ifndef NO_IPV6
 753        if (sa1->sa_family == AF_INET6)
 754                return memcmp(&((struct sockaddr_in6 *)s1)->sin6_addr,
 755                    &((struct sockaddr_in6 *)s2)->sin6_addr,
 756                    sizeof(struct in6_addr));
 757#endif
 758        return 0;
 759}
 760
 761static int max_connections = 32;
 762
 763static unsigned int live_children;
 764
 765static struct child {
 766        struct child *next;
 767        struct child_process cld;
 768        struct sockaddr_storage address;
 769} *firstborn;
 770
 771static void add_child(struct child_process *cld, struct sockaddr *addr, socklen_t addrlen)
 772{
 773        struct child *newborn, **cradle;
 774
 775        newborn = xcalloc(1, sizeof(*newborn));
 776        live_children++;
 777        memcpy(&newborn->cld, cld, sizeof(*cld));
 778        memcpy(&newborn->address, addr, addrlen);
 779        for (cradle = &firstborn; *cradle; cradle = &(*cradle)->next)
 780                if (!addrcmp(&(*cradle)->address, &newborn->address))
 781                        break;
 782        newborn->next = *cradle;
 783        *cradle = newborn;
 784}
 785
 786/*
 787 * This gets called if the number of connections grows
 788 * past "max_connections".
 789 *
 790 * We kill the newest connection from a duplicate IP.
 791 */
 792static void kill_some_child(void)
 793{
 794        const struct child *blanket, *next;
 795
 796        if (!(blanket = firstborn))
 797                return;
 798
 799        for (; (next = blanket->next); blanket = next)
 800                if (!addrcmp(&blanket->address, &next->address)) {
 801                        kill(blanket->cld.pid, SIGTERM);
 802                        break;
 803                }
 804}
 805
 806static void check_dead_children(void)
 807{
 808        int status;
 809        pid_t pid;
 810
 811        struct child **cradle, *blanket;
 812        for (cradle = &firstborn; (blanket = *cradle);)
 813                if ((pid = waitpid(blanket->cld.pid, &status, WNOHANG)) > 1) {
 814                        const char *dead = "";
 815                        if (status)
 816                                dead = " (with error)";
 817                        loginfo("[%"PRIuMAX"] Disconnected%s", (uintmax_t)pid, dead);
 818
 819                        /* remove the child */
 820                        *cradle = blanket->next;
 821                        live_children--;
 822                        child_process_clear(&blanket->cld);
 823                        free(blanket);
 824                } else
 825                        cradle = &blanket->next;
 826}
 827
 828static struct argv_array cld_argv = ARGV_ARRAY_INIT;
 829static void handle(int incoming, struct sockaddr *addr, socklen_t addrlen)
 830{
 831        struct child_process cld = CHILD_PROCESS_INIT;
 832
 833        if (max_connections && live_children >= max_connections) {
 834                kill_some_child();
 835                sleep(1);  /* give it some time to die */
 836                check_dead_children();
 837                if (live_children >= max_connections) {
 838                        close(incoming);
 839                        logerror("Too many children, dropping connection");
 840                        return;
 841                }
 842        }
 843
 844        if (addr->sa_family == AF_INET) {
 845                char buf[128] = "";
 846                struct sockaddr_in *sin_addr = (void *) addr;
 847                inet_ntop(addr->sa_family, &sin_addr->sin_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(sin_addr->sin_port));
 851#ifndef NO_IPV6
 852        } else if (addr->sa_family == AF_INET6) {
 853                char buf[128] = "";
 854                struct sockaddr_in6 *sin6_addr = (void *) addr;
 855                inet_ntop(AF_INET6, &sin6_addr->sin6_addr, buf, sizeof(buf));
 856                argv_array_pushf(&cld.env_array, "REMOTE_ADDR=[%s]", buf);
 857                argv_array_pushf(&cld.env_array, "REMOTE_PORT=%d",
 858                                 ntohs(sin6_addr->sin6_port));
 859#endif
 860        }
 861
 862        cld.argv = cld_argv.argv;
 863        cld.in = incoming;
 864        cld.out = dup(incoming);
 865
 866        if (start_command(&cld))
 867                logerror("unable to fork");
 868        else
 869                add_child(&cld, addr, addrlen);
 870}
 871
 872static void child_handler(int signo)
 873{
 874        /*
 875         * Otherwise empty handler because systemcalls will get interrupted
 876         * upon signal receipt
 877         * SysV needs the handler to be rearmed
 878         */
 879        signal(SIGCHLD, child_handler);
 880}
 881
 882static int set_reuse_addr(int sockfd)
 883{
 884        int on = 1;
 885
 886        if (!reuseaddr)
 887                return 0;
 888        return setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
 889                          &on, sizeof(on));
 890}
 891
 892struct socketlist {
 893        int *list;
 894        size_t nr;
 895        size_t alloc;
 896};
 897
 898static const char *ip2str(int family, struct sockaddr *sin, socklen_t len)
 899{
 900#ifdef NO_IPV6
 901        static char ip[INET_ADDRSTRLEN];
 902#else
 903        static char ip[INET6_ADDRSTRLEN];
 904#endif
 905
 906        switch (family) {
 907#ifndef NO_IPV6
 908        case AF_INET6:
 909                inet_ntop(family, &((struct sockaddr_in6*)sin)->sin6_addr, ip, len);
 910                break;
 911#endif
 912        case AF_INET:
 913                inet_ntop(family, &((struct sockaddr_in*)sin)->sin_addr, ip, len);
 914                break;
 915        default:
 916                xsnprintf(ip, sizeof(ip), "<unknown>");
 917        }
 918        return ip;
 919}
 920
 921#ifndef NO_IPV6
 922
 923static int setup_named_sock(char *listen_addr, int listen_port, struct socketlist *socklist)
 924{
 925        int socknum = 0;
 926        char pbuf[NI_MAXSERV];
 927        struct addrinfo hints, *ai0, *ai;
 928        int gai;
 929        long flags;
 930
 931        xsnprintf(pbuf, sizeof(pbuf), "%d", listen_port);
 932        memset(&hints, 0, sizeof(hints));
 933        hints.ai_family = AF_UNSPEC;
 934        hints.ai_socktype = SOCK_STREAM;
 935        hints.ai_protocol = IPPROTO_TCP;
 936        hints.ai_flags = AI_PASSIVE;
 937
 938        gai = getaddrinfo(listen_addr, pbuf, &hints, &ai0);
 939        if (gai) {
 940                logerror("getaddrinfo() for %s failed: %s", listen_addr, gai_strerror(gai));
 941                return 0;
 942        }
 943
 944        for (ai = ai0; ai; ai = ai->ai_next) {
 945                int sockfd;
 946
 947                sockfd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
 948                if (sockfd < 0)
 949                        continue;
 950                if (sockfd >= FD_SETSIZE) {
 951                        logerror("Socket descriptor too large");
 952                        close(sockfd);
 953                        continue;
 954                }
 955
 956#ifdef IPV6_V6ONLY
 957                if (ai->ai_family == AF_INET6) {
 958                        int on = 1;
 959                        setsockopt(sockfd, IPPROTO_IPV6, IPV6_V6ONLY,
 960                                   &on, sizeof(on));
 961                        /* Note: error is not fatal */
 962                }
 963#endif
 964
 965                if (set_reuse_addr(sockfd)) {
 966                        logerror("Could not set SO_REUSEADDR: %s", strerror(errno));
 967                        close(sockfd);
 968                        continue;
 969                }
 970
 971                if (bind(sockfd, ai->ai_addr, ai->ai_addrlen) < 0) {
 972                        logerror("Could not bind to %s: %s",
 973                                 ip2str(ai->ai_family, ai->ai_addr, ai->ai_addrlen),
 974                                 strerror(errno));
 975                        close(sockfd);
 976                        continue;       /* not fatal */
 977                }
 978                if (listen(sockfd, 5) < 0) {
 979                        logerror("Could not listen to %s: %s",
 980                                 ip2str(ai->ai_family, ai->ai_addr, ai->ai_addrlen),
 981                                 strerror(errno));
 982                        close(sockfd);
 983                        continue;       /* not fatal */
 984                }
 985
 986                flags = fcntl(sockfd, F_GETFD, 0);
 987                if (flags >= 0)
 988                        fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
 989
 990                ALLOC_GROW(socklist->list, socklist->nr + 1, socklist->alloc);
 991                socklist->list[socklist->nr++] = sockfd;
 992                socknum++;
 993        }
 994
 995        freeaddrinfo(ai0);
 996
 997        return socknum;
 998}
 999
1000#else /* NO_IPV6 */
1001
1002static int setup_named_sock(char *listen_addr, int listen_port, struct socketlist *socklist)
1003{
1004        struct sockaddr_in sin;
1005        int sockfd;
1006        long flags;
1007
1008        memset(&sin, 0, sizeof sin);
1009        sin.sin_family = AF_INET;
1010        sin.sin_port = htons(listen_port);
1011
1012        if (listen_addr) {
1013                /* Well, host better be an IP address here. */
1014                if (inet_pton(AF_INET, listen_addr, &sin.sin_addr.s_addr) <= 0)
1015                        return 0;
1016        } else {
1017                sin.sin_addr.s_addr = htonl(INADDR_ANY);
1018        }
1019
1020        sockfd = socket(AF_INET, SOCK_STREAM, 0);
1021        if (sockfd < 0)
1022                return 0;
1023
1024        if (set_reuse_addr(sockfd)) {
1025                logerror("Could not set SO_REUSEADDR: %s", strerror(errno));
1026                close(sockfd);
1027                return 0;
1028        }
1029
1030        if ( bind(sockfd, (struct sockaddr *)&sin, sizeof sin) < 0 ) {
1031                logerror("Could not bind to %s: %s",
1032                         ip2str(AF_INET, (struct sockaddr *)&sin, sizeof(sin)),
1033                         strerror(errno));
1034                close(sockfd);
1035                return 0;
1036        }
1037
1038        if (listen(sockfd, 5) < 0) {
1039                logerror("Could not listen to %s: %s",
1040                         ip2str(AF_INET, (struct sockaddr *)&sin, sizeof(sin)),
1041                         strerror(errno));
1042                close(sockfd);
1043                return 0;
1044        }
1045
1046        flags = fcntl(sockfd, F_GETFD, 0);
1047        if (flags >= 0)
1048                fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
1049
1050        ALLOC_GROW(socklist->list, socklist->nr + 1, socklist->alloc);
1051        socklist->list[socklist->nr++] = sockfd;
1052        return 1;
1053}
1054
1055#endif
1056
1057static void socksetup(struct string_list *listen_addr, int listen_port, struct socketlist *socklist)
1058{
1059        if (!listen_addr->nr)
1060                setup_named_sock(NULL, listen_port, socklist);
1061        else {
1062                int i, socknum;
1063                for (i = 0; i < listen_addr->nr; i++) {
1064                        socknum = setup_named_sock(listen_addr->items[i].string,
1065                                                   listen_port, socklist);
1066
1067                        if (socknum == 0)
1068                                logerror("unable to allocate any listen sockets for host %s on port %u",
1069                                         listen_addr->items[i].string, listen_port);
1070                }
1071        }
1072}
1073
1074static int service_loop(struct socketlist *socklist)
1075{
1076        struct pollfd *pfd;
1077        int i;
1078
1079        pfd = xcalloc(socklist->nr, sizeof(struct pollfd));
1080
1081        for (i = 0; i < socklist->nr; i++) {
1082                pfd[i].fd = socklist->list[i];
1083                pfd[i].events = POLLIN;
1084        }
1085
1086        signal(SIGCHLD, child_handler);
1087
1088        for (;;) {
1089                int i;
1090
1091                check_dead_children();
1092
1093                if (poll(pfd, socklist->nr, -1) < 0) {
1094                        if (errno != EINTR) {
1095                                logerror("Poll failed, resuming: %s",
1096                                      strerror(errno));
1097                                sleep(1);
1098                        }
1099                        continue;
1100                }
1101
1102                for (i = 0; i < socklist->nr; i++) {
1103                        if (pfd[i].revents & POLLIN) {
1104                                union {
1105                                        struct sockaddr sa;
1106                                        struct sockaddr_in sai;
1107#ifndef NO_IPV6
1108                                        struct sockaddr_in6 sai6;
1109#endif
1110                                } ss;
1111                                socklen_t sslen = sizeof(ss);
1112                                int incoming = accept(pfd[i].fd, &ss.sa, &sslen);
1113                                if (incoming < 0) {
1114                                        switch (errno) {
1115                                        case EAGAIN:
1116                                        case EINTR:
1117                                        case ECONNABORTED:
1118                                                continue;
1119                                        default:
1120                                                die_errno("accept returned");
1121                                        }
1122                                }
1123                                handle(incoming, &ss.sa, sslen);
1124                        }
1125                }
1126        }
1127}
1128
1129#ifdef NO_POSIX_GOODIES
1130
1131struct credentials;
1132
1133static void drop_privileges(struct credentials *cred)
1134{
1135        /* nothing */
1136}
1137
1138static struct credentials *prepare_credentials(const char *user_name,
1139    const char *group_name)
1140{
1141        die("--user not supported on this platform");
1142}
1143
1144#else
1145
1146struct credentials {
1147        struct passwd *pass;
1148        gid_t gid;
1149};
1150
1151static void drop_privileges(struct credentials *cred)
1152{
1153        if (cred && (initgroups(cred->pass->pw_name, cred->gid) ||
1154            setgid (cred->gid) || setuid(cred->pass->pw_uid)))
1155                die("cannot drop privileges");
1156}
1157
1158static struct credentials *prepare_credentials(const char *user_name,
1159    const char *group_name)
1160{
1161        static struct credentials c;
1162
1163        c.pass = getpwnam(user_name);
1164        if (!c.pass)
1165                die("user not found - %s", user_name);
1166
1167        if (!group_name)
1168                c.gid = c.pass->pw_gid;
1169        else {
1170                struct group *group = getgrnam(group_name);
1171                if (!group)
1172                        die("group not found - %s", group_name);
1173
1174                c.gid = group->gr_gid;
1175        }
1176
1177        return &c;
1178}
1179#endif
1180
1181static int serve(struct string_list *listen_addr, int listen_port,
1182    struct credentials *cred)
1183{
1184        struct socketlist socklist = { NULL, 0, 0 };
1185
1186        socksetup(listen_addr, listen_port, &socklist);
1187        if (socklist.nr == 0)
1188                die("unable to allocate any listen sockets on port %u",
1189                    listen_port);
1190
1191        drop_privileges(cred);
1192
1193        loginfo("Ready to rumble");
1194
1195        return service_loop(&socklist);
1196}
1197
1198int main(int argc, char **argv)
1199{
1200        int listen_port = 0;
1201        struct string_list listen_addr = STRING_LIST_INIT_NODUP;
1202        int serve_mode = 0, inetd_mode = 0;
1203        const char *pid_file = NULL, *user_name = NULL, *group_name = NULL;
1204        int detach = 0;
1205        struct credentials *cred = NULL;
1206        int i;
1207
1208        git_setup_gettext();
1209
1210        git_extract_argv0_path(argv[0]);
1211
1212        for (i = 1; i < argc; i++) {
1213                char *arg = argv[i];
1214                const char *v;
1215
1216                if (skip_prefix(arg, "--listen=", &v)) {
1217                        string_list_append(&listen_addr, xstrdup_tolower(v));
1218                        continue;
1219                }
1220                if (skip_prefix(arg, "--port=", &v)) {
1221                        char *end;
1222                        unsigned long n;
1223                        n = strtoul(v, &end, 0);
1224                        if (*v && !*end) {
1225                                listen_port = n;
1226                                continue;
1227                        }
1228                }
1229                if (!strcmp(arg, "--serve")) {
1230                        serve_mode = 1;
1231                        continue;
1232                }
1233                if (!strcmp(arg, "--inetd")) {
1234                        inetd_mode = 1;
1235                        log_syslog = 1;
1236                        continue;
1237                }
1238                if (!strcmp(arg, "--verbose")) {
1239                        verbose = 1;
1240                        continue;
1241                }
1242                if (!strcmp(arg, "--syslog")) {
1243                        log_syslog = 1;
1244                        continue;
1245                }
1246                if (!strcmp(arg, "--export-all")) {
1247                        export_all_trees = 1;
1248                        continue;
1249                }
1250                if (skip_prefix(arg, "--access-hook=", &v)) {
1251                        access_hook = v;
1252                        continue;
1253                }
1254                if (skip_prefix(arg, "--timeout=", &v)) {
1255                        timeout = atoi(v);
1256                        continue;
1257                }
1258                if (skip_prefix(arg, "--init-timeout=", &v)) {
1259                        init_timeout = atoi(v);
1260                        continue;
1261                }
1262                if (skip_prefix(arg, "--max-connections=", &v)) {
1263                        max_connections = atoi(v);
1264                        if (max_connections < 0)
1265                                max_connections = 0;            /* unlimited */
1266                        continue;
1267                }
1268                if (!strcmp(arg, "--strict-paths")) {
1269                        strict_paths = 1;
1270                        continue;
1271                }
1272                if (skip_prefix(arg, "--base-path=", &v)) {
1273                        base_path = v;
1274                        continue;
1275                }
1276                if (!strcmp(arg, "--base-path-relaxed")) {
1277                        base_path_relaxed = 1;
1278                        continue;
1279                }
1280                if (skip_prefix(arg, "--interpolated-path=", &v)) {
1281                        interpolated_path = v;
1282                        continue;
1283                }
1284                if (!strcmp(arg, "--reuseaddr")) {
1285                        reuseaddr = 1;
1286                        continue;
1287                }
1288                if (!strcmp(arg, "--user-path")) {
1289                        user_path = "";
1290                        continue;
1291                }
1292                if (skip_prefix(arg, "--user-path=", &v)) {
1293                        user_path = v;
1294                        continue;
1295                }
1296                if (skip_prefix(arg, "--pid-file=", &v)) {
1297                        pid_file = v;
1298                        continue;
1299                }
1300                if (!strcmp(arg, "--detach")) {
1301                        detach = 1;
1302                        log_syslog = 1;
1303                        continue;
1304                }
1305                if (skip_prefix(arg, "--user=", &v)) {
1306                        user_name = v;
1307                        continue;
1308                }
1309                if (skip_prefix(arg, "--group=", &v)) {
1310                        group_name = v;
1311                        continue;
1312                }
1313                if (skip_prefix(arg, "--enable=", &v)) {
1314                        enable_service(v, 1);
1315                        continue;
1316                }
1317                if (skip_prefix(arg, "--disable=", &v)) {
1318                        enable_service(v, 0);
1319                        continue;
1320                }
1321                if (skip_prefix(arg, "--allow-override=", &v)) {
1322                        make_service_overridable(v, 1);
1323                        continue;
1324                }
1325                if (skip_prefix(arg, "--forbid-override=", &v)) {
1326                        make_service_overridable(v, 0);
1327                        continue;
1328                }
1329                if (!strcmp(arg, "--informative-errors")) {
1330                        informative_errors = 1;
1331                        continue;
1332                }
1333                if (!strcmp(arg, "--no-informative-errors")) {
1334                        informative_errors = 0;
1335                        continue;
1336                }
1337                if (!strcmp(arg, "--")) {
1338                        ok_paths = &argv[i+1];
1339                        break;
1340                } else if (arg[0] != '-') {
1341                        ok_paths = &argv[i];
1342                        break;
1343                }
1344
1345                usage(daemon_usage);
1346        }
1347
1348        if (log_syslog) {
1349                openlog("git-daemon", LOG_PID, LOG_DAEMON);
1350                set_die_routine(daemon_die);
1351        } else
1352                /* avoid splitting a message in the middle */
1353                setvbuf(stderr, NULL, _IOFBF, 4096);
1354
1355        if (inetd_mode && (detach || group_name || user_name))
1356                die("--detach, --user and --group are incompatible with --inetd");
1357
1358        if (inetd_mode && (listen_port || (listen_addr.nr > 0)))
1359                die("--listen= and --port= are incompatible with --inetd");
1360        else if (listen_port == 0)
1361                listen_port = DEFAULT_GIT_PORT;
1362
1363        if (group_name && !user_name)
1364                die("--group supplied without --user");
1365
1366        if (user_name)
1367                cred = prepare_credentials(user_name, group_name);
1368
1369        if (strict_paths && (!ok_paths || !*ok_paths))
1370                die("option --strict-paths requires a whitelist");
1371
1372        if (base_path && !is_directory(base_path))
1373                die("base-path '%s' does not exist or is not a directory",
1374                    base_path);
1375
1376        if (inetd_mode) {
1377                if (!freopen("/dev/null", "w", stderr))
1378                        die_errno("failed to redirect stderr to /dev/null");
1379        }
1380
1381        if (inetd_mode || serve_mode)
1382                return execute();
1383
1384        if (detach) {
1385                if (daemonize())
1386                        die("--detach not supported on this platform");
1387        } else
1388                sanitize_stdfds();
1389
1390        if (pid_file)
1391                write_file(pid_file, "%"PRIuMAX, (uintmax_t) getpid());
1392
1393        /* prepare argv for serving-processes */
1394        argv_array_push(&cld_argv, argv[0]); /* git-daemon */
1395        argv_array_push(&cld_argv, "--serve");
1396        for (i = 1; i < argc; ++i)
1397                argv_array_push(&cld_argv, argv[i]);
1398
1399        return serve(&listen_addr, listen_port, cred);
1400}