Andrew's git / gitweb.git / daemon.c
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daemon.con commit verify_path: drop clever fallthrough (e19e5e6)
   1#include "cache.h"
   2#include "pkt-line.h"
   3#include "run-command.h"
   4#include "strbuf.h"
   5#include "string-list.h"
   6
   7#ifdef NO_INITGROUPS
   8#define initgroups(x, y) (0) /* nothing */
   9#endif
  10
  11static int log_syslog;
  12static int verbose;
  13static int reuseaddr;
  14static int informative_errors;
  15
  16static const char daemon_usage[] =
  17"git daemon [--verbose] [--syslog] [--export-all]\n"
  18"           [--timeout=<n>] [--init-timeout=<n>] [--max-connections=<n>]\n"
  19"           [--strict-paths] [--base-path=<path>] [--base-path-relaxed]\n"
  20"           [--user-path | --user-path=<path>]\n"
  21"           [--interpolated-path=<path>]\n"
  22"           [--reuseaddr] [--pid-file=<file>]\n"
  23"           [--(enable|disable|allow-override|forbid-override)=<service>]\n"
  24"           [--access-hook=<path>]\n"
  25"           [--inetd | [--listen=<host_or_ipaddr>] [--port=<n>]\n"
  26"                      [--detach] [--user=<user> [--group=<group>]]\n"
  27"           [<directory>...]";
  28
  29/* List of acceptable pathname prefixes */
  30static const char **ok_paths;
  31static int strict_paths;
  32
  33/* If this is set, git-daemon-export-ok is not required */
  34static int export_all_trees;
  35
  36/* Take all paths relative to this one if non-NULL */
  37static const char *base_path;
  38static const char *interpolated_path;
  39static int base_path_relaxed;
  40
  41/* If defined, ~user notation is allowed and the string is inserted
  42 * after ~user/.  E.g. a request to git://host/~alice/frotz would
  43 * go to /home/alice/pub_git/frotz with --user-path=pub_git.
  44 */
  45static const char *user_path;
  46
  47/* Timeout, and initial timeout */
  48static unsigned int timeout;
  49static unsigned int init_timeout;
  50
  51struct hostinfo {
  52        struct strbuf hostname;
  53        struct strbuf canon_hostname;
  54        struct strbuf ip_address;
  55        struct strbuf tcp_port;
  56        unsigned int hostname_lookup_done:1;
  57        unsigned int saw_extended_args:1;
  58};
  59
  60static void lookup_hostname(struct hostinfo *hi);
  61
  62static const char *get_canon_hostname(struct hostinfo *hi)
  63{
  64        lookup_hostname(hi);
  65        return hi->canon_hostname.buf;
  66}
  67
  68static const char *get_ip_address(struct hostinfo *hi)
  69{
  70        lookup_hostname(hi);
  71        return hi->ip_address.buf;
  72}
  73
  74static void logreport(int priority, const char *err, va_list params)
  75{
  76        if (log_syslog) {
  77                char buf[1024];
  78                vsnprintf(buf, sizeof(buf), err, params);
  79                syslog(priority, "%s", buf);
  80        } else {
  81                /*
  82                 * Since stderr is set to buffered mode, the
  83                 * logging of different processes will not overlap
  84                 * unless they overflow the (rather big) buffers.
  85                 */
  86                fprintf(stderr, "[%"PRIuMAX"] ", (uintmax_t)getpid());
  87                vfprintf(stderr, err, params);
  88                fputc('\n', stderr);
  89                fflush(stderr);
  90        }
  91}
  92
  93__attribute__((format (printf, 1, 2)))
  94static void logerror(const char *err, ...)
  95{
  96        va_list params;
  97        va_start(params, err);
  98        logreport(LOG_ERR, err, params);
  99        va_end(params);
 100}
 101
 102__attribute__((format (printf, 1, 2)))
 103static void loginfo(const char *err, ...)
 104{
 105        va_list params;
 106        if (!verbose)
 107                return;
 108        va_start(params, err);
 109        logreport(LOG_INFO, err, params);
 110        va_end(params);
 111}
 112
 113static void NORETURN daemon_die(const char *err, va_list params)
 114{
 115        logreport(LOG_ERR, err, params);
 116        exit(1);
 117}
 118
 119struct expand_path_context {
 120        const char *directory;
 121        struct hostinfo *hostinfo;
 122};
 123
 124static size_t expand_path(struct strbuf *sb, const char *placeholder, void *ctx)
 125{
 126        struct expand_path_context *context = ctx;
 127        struct hostinfo *hi = context->hostinfo;
 128
 129        switch (placeholder[0]) {
 130        case 'H':
 131                strbuf_addbuf(sb, &hi->hostname);
 132                return 1;
 133        case 'C':
 134                if (placeholder[1] == 'H') {
 135                        strbuf_addstr(sb, get_canon_hostname(hi));
 136                        return 2;
 137                }
 138                break;
 139        case 'I':
 140                if (placeholder[1] == 'P') {
 141                        strbuf_addstr(sb, get_ip_address(hi));
 142                        return 2;
 143                }
 144                break;
 145        case 'P':
 146                strbuf_addbuf(sb, &hi->tcp_port);
 147                return 1;
 148        case 'D':
 149                strbuf_addstr(sb, context->directory);
 150                return 1;
 151        }
 152        return 0;
 153}
 154
 155static const char *path_ok(const char *directory, struct hostinfo *hi)
 156{
 157        static char rpath[PATH_MAX];
 158        static char interp_path[PATH_MAX];
 159        size_t rlen;
 160        const char *path;
 161        const char *dir;
 162
 163        dir = directory;
 164
 165        if (daemon_avoid_alias(dir)) {
 166                logerror("'%s': aliased", dir);
 167                return NULL;
 168        }
 169
 170        if (*dir == '~') {
 171                if (!user_path) {
 172                        logerror("'%s': User-path not allowed", dir);
 173                        return NULL;
 174                }
 175                if (*user_path) {
 176                        /* Got either "~alice" or "~alice/foo";
 177                         * rewrite them to "~alice/%s" or
 178                         * "~alice/%s/foo".
 179                         */
 180                        int namlen, restlen = strlen(dir);
 181                        const char *slash = strchr(dir, '/');
 182                        if (!slash)
 183                                slash = dir + restlen;
 184                        namlen = slash - dir;
 185                        restlen -= namlen;
 186                        loginfo("userpath <%s>, request <%s>, namlen %d, restlen %d, slash <%s>", user_path, dir, namlen, restlen, slash);
 187                        rlen = snprintf(rpath, sizeof(rpath), "%.*s/%s%.*s",
 188                                        namlen, dir, user_path, restlen, slash);
 189                        if (rlen >= sizeof(rpath)) {
 190                                logerror("user-path too large: %s", rpath);
 191                                return NULL;
 192                        }
 193                        dir = rpath;
 194                }
 195        }
 196        else if (interpolated_path && hi->saw_extended_args) {
 197                struct strbuf expanded_path = STRBUF_INIT;
 198                struct expand_path_context context;
 199
 200                context.directory = directory;
 201                context.hostinfo = hi;
 202
 203                if (*dir != '/') {
 204                        /* Allow only absolute */
 205                        logerror("'%s': Non-absolute path denied (interpolated-path active)", dir);
 206                        return NULL;
 207                }
 208
 209                strbuf_expand(&expanded_path, interpolated_path,
 210                              expand_path, &context);
 211
 212                rlen = strlcpy(interp_path, expanded_path.buf,
 213                               sizeof(interp_path));
 214                if (rlen >= sizeof(interp_path)) {
 215                        logerror("interpolated path too large: %s",
 216                                 interp_path);
 217                        return NULL;
 218                }
 219
 220                strbuf_release(&expanded_path);
 221                loginfo("Interpolated dir '%s'", interp_path);
 222
 223                dir = interp_path;
 224        }
 225        else if (base_path) {
 226                if (*dir != '/') {
 227                        /* Allow only absolute */
 228                        logerror("'%s': Non-absolute path denied (base-path active)", dir);
 229                        return NULL;
 230                }
 231                rlen = snprintf(rpath, sizeof(rpath), "%s%s", base_path, dir);
 232                if (rlen >= sizeof(rpath)) {
 233                        logerror("base-path too large: %s", rpath);
 234                        return NULL;
 235                }
 236                dir = rpath;
 237        }
 238
 239        path = enter_repo(dir, strict_paths);
 240        if (!path && base_path && base_path_relaxed) {
 241                /*
 242                 * if we fail and base_path_relaxed is enabled, try without
 243                 * prefixing the base path
 244                 */
 245                dir = directory;
 246                path = enter_repo(dir, strict_paths);
 247        }
 248
 249        if (!path) {
 250                logerror("'%s' does not appear to be a git repository", dir);
 251                return NULL;
 252        }
 253
 254        if ( ok_paths && *ok_paths ) {
 255                const char **pp;
 256                int pathlen = strlen(path);
 257
 258                /* The validation is done on the paths after enter_repo
 259                 * appends optional {.git,.git/.git} and friends, but
 260                 * it does not use getcwd().  So if your /pub is
 261                 * a symlink to /mnt/pub, you can whitelist /pub and
 262                 * do not have to say /mnt/pub.
 263                 * Do not say /pub/.
 264                 */
 265                for ( pp = ok_paths ; *pp ; pp++ ) {
 266                        int len = strlen(*pp);
 267                        if (len <= pathlen &&
 268                            !memcmp(*pp, path, len) &&
 269                            (path[len] == '\0' ||
 270                             (!strict_paths && path[len] == '/')))
 271                                return path;
 272                }
 273        }
 274        else {
 275                /* be backwards compatible */
 276                if (!strict_paths)
 277                        return path;
 278        }
 279
 280        logerror("'%s': not in whitelist", path);
 281        return NULL;            /* Fallthrough. Deny by default */
 282}
 283
 284typedef int (*daemon_service_fn)(void);
 285struct daemon_service {
 286        const char *name;
 287        const char *config_name;
 288        daemon_service_fn fn;
 289        int enabled;
 290        int overridable;
 291};
 292
 293static int daemon_error(const char *dir, const char *msg)
 294{
 295        if (!informative_errors)
 296                msg = "access denied or repository not exported";
 297        packet_write_fmt(1, "ERR %s: %s", msg, dir);
 298        return -1;
 299}
 300
 301static const char *access_hook;
 302
 303static int run_access_hook(struct daemon_service *service, const char *dir,
 304                           const char *path, struct hostinfo *hi)
 305{
 306        struct child_process child = CHILD_PROCESS_INIT;
 307        struct strbuf buf = STRBUF_INIT;
 308        const char *argv[8];
 309        const char **arg = argv;
 310        char *eol;
 311        int seen_errors = 0;
 312
 313        *arg++ = access_hook;
 314        *arg++ = service->name;
 315        *arg++ = path;
 316        *arg++ = hi->hostname.buf;
 317        *arg++ = get_canon_hostname(hi);
 318        *arg++ = get_ip_address(hi);
 319        *arg++ = hi->tcp_port.buf;
 320        *arg = NULL;
 321
 322        child.use_shell = 1;
 323        child.argv = argv;
 324        child.no_stdin = 1;
 325        child.no_stderr = 1;
 326        child.out = -1;
 327        if (start_command(&child)) {
 328                logerror("daemon access hook '%s' failed to start",
 329                         access_hook);
 330                goto error_return;
 331        }
 332        if (strbuf_read(&buf, child.out, 0) < 0) {
 333                logerror("failed to read from pipe to daemon access hook '%s'",
 334                         access_hook);
 335                strbuf_reset(&buf);
 336                seen_errors = 1;
 337        }
 338        if (close(child.out) < 0) {
 339                logerror("failed to close pipe to daemon access hook '%s'",
 340                         access_hook);
 341                seen_errors = 1;
 342        }
 343        if (finish_command(&child))
 344                seen_errors = 1;
 345
 346        if (!seen_errors) {
 347                strbuf_release(&buf);
 348                return 0;
 349        }
 350
 351error_return:
 352        strbuf_ltrim(&buf);
 353        if (!buf.len)
 354                strbuf_addstr(&buf, "service rejected");
 355        eol = strchr(buf.buf, '\n');
 356        if (eol)
 357                *eol = '\0';
 358        errno = EACCES;
 359        daemon_error(dir, buf.buf);
 360        strbuf_release(&buf);
 361        return -1;
 362}
 363
 364static int run_service(const char *dir, struct daemon_service *service,
 365                       struct hostinfo *hi)
 366{
 367        const char *path;
 368        int enabled = service->enabled;
 369        struct strbuf var = STRBUF_INIT;
 370
 371        loginfo("Request %s for '%s'", service->name, dir);
 372
 373        if (!enabled && !service->overridable) {
 374                logerror("'%s': service not enabled.", service->name);
 375                errno = EACCES;
 376                return daemon_error(dir, "service not enabled");
 377        }
 378
 379        if (!(path = path_ok(dir, hi)))
 380                return daemon_error(dir, "no such repository");
 381
 382        /*
 383         * Security on the cheap.
 384         *
 385         * We want a readable HEAD, usable "objects" directory, and
 386         * a "git-daemon-export-ok" flag that says that the other side
 387         * is ok with us doing this.
 388         *
 389         * path_ok() uses enter_repo() and does whitelist checking.
 390         * We only need to make sure the repository is exported.
 391         */
 392
 393        if (!export_all_trees && access("git-daemon-export-ok", F_OK)) {
 394                logerror("'%s': repository not exported.", path);
 395                errno = EACCES;
 396                return daemon_error(dir, "repository not exported");
 397        }
 398
 399        if (service->overridable) {
 400                strbuf_addf(&var, "daemon.%s", service->config_name);
 401                git_config_get_bool(var.buf, &enabled);
 402                strbuf_release(&var);
 403        }
 404        if (!enabled) {
 405                logerror("'%s': service not enabled for '%s'",
 406                         service->name, path);
 407                errno = EACCES;
 408                return daemon_error(dir, "service not enabled");
 409        }
 410
 411        /*
 412         * Optionally, a hook can choose to deny access to the
 413         * repository depending on the phase of the moon.
 414         */
 415        if (access_hook && run_access_hook(service, dir, path, hi))
 416                return -1;
 417
 418        /*
 419         * We'll ignore SIGTERM from now on, we have a
 420         * good client.
 421         */
 422        signal(SIGTERM, SIG_IGN);
 423
 424        return service->fn();
 425}
 426
 427static void copy_to_log(int fd)
 428{
 429        struct strbuf line = STRBUF_INIT;
 430        FILE *fp;
 431
 432        fp = fdopen(fd, "r");
 433        if (fp == NULL) {
 434                logerror("fdopen of error channel failed");
 435                close(fd);
 436                return;
 437        }
 438
 439        while (strbuf_getline_lf(&line, fp) != EOF) {
 440                logerror("%s", line.buf);
 441                strbuf_setlen(&line, 0);
 442        }
 443
 444        strbuf_release(&line);
 445        fclose(fp);
 446}
 447
 448static int run_service_command(struct child_process *cld)
 449{
 450        argv_array_push(&cld->args, ".");
 451        cld->git_cmd = 1;
 452        cld->err = -1;
 453        if (start_command(cld))
 454                return -1;
 455
 456        close(0);
 457        close(1);
 458
 459        copy_to_log(cld->err);
 460
 461        return finish_command(cld);
 462}
 463
 464static int upload_pack(void)
 465{
 466        struct child_process cld = CHILD_PROCESS_INIT;
 467        argv_array_pushl(&cld.args, "upload-pack", "--strict", NULL);
 468        argv_array_pushf(&cld.args, "--timeout=%u", timeout);
 469        return run_service_command(&cld);
 470}
 471
 472static int upload_archive(void)
 473{
 474        struct child_process cld = CHILD_PROCESS_INIT;
 475        argv_array_push(&cld.args, "upload-archive");
 476        return run_service_command(&cld);
 477}
 478
 479static int receive_pack(void)
 480{
 481        struct child_process cld = CHILD_PROCESS_INIT;
 482        argv_array_push(&cld.args, "receive-pack");
 483        return run_service_command(&cld);
 484}
 485
 486static struct daemon_service daemon_service[] = {
 487        { "upload-archive", "uploadarch", upload_archive, 0, 1 },
 488        { "upload-pack", "uploadpack", upload_pack, 1, 1 },
 489        { "receive-pack", "receivepack", receive_pack, 0, 1 },
 490};
 491
 492static void enable_service(const char *name, int ena)
 493{
 494        int i;
 495        for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 496                if (!strcmp(daemon_service[i].name, name)) {
 497                        daemon_service[i].enabled = ena;
 498                        return;
 499                }
 500        }
 501        die("No such service %s", name);
 502}
 503
 504static void make_service_overridable(const char *name, int ena)
 505{
 506        int i;
 507        for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 508                if (!strcmp(daemon_service[i].name, name)) {
 509                        daemon_service[i].overridable = ena;
 510                        return;
 511                }
 512        }
 513        die("No such service %s", name);
 514}
 515
 516static void parse_host_and_port(char *hostport, char **host,
 517        char **port)
 518{
 519        if (*hostport == '[') {
 520                char *end;
 521
 522                end = strchr(hostport, ']');
 523                if (!end)
 524                        die("Invalid request ('[' without ']')");
 525                *end = '\0';
 526                *host = hostport + 1;
 527                if (!end[1])
 528                        *port = NULL;
 529                else if (end[1] == ':')
 530                        *port = end + 2;
 531                else
 532                        die("Garbage after end of host part");
 533        } else {
 534                *host = hostport;
 535                *port = strrchr(hostport, ':');
 536                if (*port) {
 537                        **port = '\0';
 538                        ++*port;
 539                }
 540        }
 541}
 542
 543/*
 544 * Sanitize a string from the client so that it's OK to be inserted into a
 545 * filesystem path. Specifically, we disallow slashes, runs of "..", and
 546 * trailing and leading dots, which means that the client cannot escape
 547 * our base path via ".." traversal.
 548 */
 549static void sanitize_client(struct strbuf *out, const char *in)
 550{
 551        for (; *in; in++) {
 552                if (*in == '/')
 553                        continue;
 554                if (*in == '.' && (!out->len || out->buf[out->len - 1] == '.'))
 555                        continue;
 556                strbuf_addch(out, *in);
 557        }
 558
 559        while (out->len && out->buf[out->len - 1] == '.')
 560                strbuf_setlen(out, out->len - 1);
 561}
 562
 563/*
 564 * Like sanitize_client, but we also perform any canonicalization
 565 * to make life easier on the admin.
 566 */
 567static void canonicalize_client(struct strbuf *out, const char *in)
 568{
 569        sanitize_client(out, in);
 570        strbuf_tolower(out);
 571}
 572
 573/*
 574 * Read the host as supplied by the client connection.
 575 */
 576static void parse_host_arg(struct hostinfo *hi, char *extra_args, int buflen)
 577{
 578        char *val;
 579        int vallen;
 580        char *end = extra_args + buflen;
 581
 582        if (extra_args < end && *extra_args) {
 583                hi->saw_extended_args = 1;
 584                if (strncasecmp("host=", extra_args, 5) == 0) {
 585                        val = extra_args + 5;
 586                        vallen = strlen(val) + 1;
 587                        if (*val) {
 588                                /* Split <host>:<port> at colon. */
 589                                char *host;
 590                                char *port;
 591                                parse_host_and_port(val, &host, &port);
 592                                if (port)
 593                                        sanitize_client(&hi->tcp_port, port);
 594                                canonicalize_client(&hi->hostname, host);
 595                                hi->hostname_lookup_done = 0;
 596                        }
 597
 598                        /* On to the next one */
 599                        extra_args = val + vallen;
 600                }
 601                if (extra_args < end && *extra_args)
 602                        die("Invalid request");
 603        }
 604}
 605
 606/*
 607 * Locate canonical hostname and its IP address.
 608 */
 609static void lookup_hostname(struct hostinfo *hi)
 610{
 611        if (!hi->hostname_lookup_done && hi->hostname.len) {
 612#ifndef NO_IPV6
 613                struct addrinfo hints;
 614                struct addrinfo *ai;
 615                int gai;
 616                static char addrbuf[HOST_NAME_MAX + 1];
 617
 618                memset(&hints, 0, sizeof(hints));
 619                hints.ai_flags = AI_CANONNAME;
 620
 621                gai = getaddrinfo(hi->hostname.buf, NULL, &hints, &ai);
 622                if (!gai) {
 623                        struct sockaddr_in *sin_addr = (void *)ai->ai_addr;
 624
 625                        inet_ntop(AF_INET, &sin_addr->sin_addr,
 626                                  addrbuf, sizeof(addrbuf));
 627                        strbuf_addstr(&hi->ip_address, addrbuf);
 628
 629                        if (ai->ai_canonname)
 630                                sanitize_client(&hi->canon_hostname,
 631                                                ai->ai_canonname);
 632                        else
 633                                strbuf_addbuf(&hi->canon_hostname,
 634                                              &hi->ip_address);
 635
 636                        freeaddrinfo(ai);
 637                }
 638#else
 639                struct hostent *hent;
 640                struct sockaddr_in sa;
 641                char **ap;
 642                static char addrbuf[HOST_NAME_MAX + 1];
 643
 644                hent = gethostbyname(hi->hostname.buf);
 645                if (hent) {
 646                        ap = hent->h_addr_list;
 647                        memset(&sa, 0, sizeof sa);
 648                        sa.sin_family = hent->h_addrtype;
 649                        sa.sin_port = htons(0);
 650                        memcpy(&sa.sin_addr, *ap, hent->h_length);
 651
 652                        inet_ntop(hent->h_addrtype, &sa.sin_addr,
 653                                  addrbuf, sizeof(addrbuf));
 654
 655                        sanitize_client(&hi->canon_hostname, hent->h_name);
 656                        strbuf_addstr(&hi->ip_address, addrbuf);
 657                }
 658#endif
 659                hi->hostname_lookup_done = 1;
 660        }
 661}
 662
 663static void hostinfo_init(struct hostinfo *hi)
 664{
 665        memset(hi, 0, sizeof(*hi));
 666        strbuf_init(&hi->hostname, 0);
 667        strbuf_init(&hi->canon_hostname, 0);
 668        strbuf_init(&hi->ip_address, 0);
 669        strbuf_init(&hi->tcp_port, 0);
 670}
 671
 672static void hostinfo_clear(struct hostinfo *hi)
 673{
 674        strbuf_release(&hi->hostname);
 675        strbuf_release(&hi->canon_hostname);
 676        strbuf_release(&hi->ip_address);
 677        strbuf_release(&hi->tcp_port);
 678}
 679
 680static void set_keep_alive(int sockfd)
 681{
 682        int ka = 1;
 683
 684        if (setsockopt(sockfd, SOL_SOCKET, SO_KEEPALIVE, &ka, sizeof(ka)) < 0) {
 685                if (errno != ENOTSOCK)
 686                        logerror("unable to set SO_KEEPALIVE on socket: %s",
 687                                strerror(errno));
 688        }
 689}
 690
 691static int execute(void)
 692{
 693        char *line = packet_buffer;
 694        int pktlen, len, i;
 695        char *addr = getenv("REMOTE_ADDR"), *port = getenv("REMOTE_PORT");
 696        struct hostinfo hi;
 697
 698        hostinfo_init(&hi);
 699
 700        if (addr)
 701                loginfo("Connection from %s:%s", addr, port);
 702
 703        set_keep_alive(0);
 704        alarm(init_timeout ? init_timeout : timeout);
 705        pktlen = packet_read(0, NULL, NULL, packet_buffer, sizeof(packet_buffer), 0);
 706        alarm(0);
 707
 708        len = strlen(line);
 709        if (pktlen != len)
 710                loginfo("Extended attributes (%d bytes) exist <%.*s>",
 711                        (int) pktlen - len,
 712                        (int) pktlen - len, line + len + 1);
 713        if (len && line[len-1] == '\n') {
 714                line[--len] = 0;
 715                pktlen--;
 716        }
 717
 718        if (len != pktlen)
 719                parse_host_arg(&hi, line + len + 1, pktlen - len - 1);
 720
 721        for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 722                struct daemon_service *s = &(daemon_service[i]);
 723                const char *arg;
 724
 725                if (skip_prefix(line, "git-", &arg) &&
 726                    skip_prefix(arg, s->name, &arg) &&
 727                    *arg++ == ' ') {
 728                        /*
 729                         * Note: The directory here is probably context sensitive,
 730                         * and might depend on the actual service being performed.
 731                         */
 732                        int rc = run_service(arg, s, &hi);
 733                        hostinfo_clear(&hi);
 734                        return rc;
 735                }
 736        }
 737
 738        hostinfo_clear(&hi);
 739        logerror("Protocol error: '%s'", line);
 740        return -1;
 741}
 742
 743static int addrcmp(const struct sockaddr_storage *s1,
 744    const struct sockaddr_storage *s2)
 745{
 746        const struct sockaddr *sa1 = (const struct sockaddr*) s1;
 747        const struct sockaddr *sa2 = (const struct sockaddr*) s2;
 748
 749        if (sa1->sa_family != sa2->sa_family)
 750                return sa1->sa_family - sa2->sa_family;
 751        if (sa1->sa_family == AF_INET)
 752                return memcmp(&((struct sockaddr_in *)s1)->sin_addr,
 753                    &((struct sockaddr_in *)s2)->sin_addr,
 754                    sizeof(struct in_addr));
 755#ifndef NO_IPV6
 756        if (sa1->sa_family == AF_INET6)
 757                return memcmp(&((struct sockaddr_in6 *)s1)->sin6_addr,
 758                    &((struct sockaddr_in6 *)s2)->sin6_addr,
 759                    sizeof(struct in6_addr));
 760#endif
 761        return 0;
 762}
 763
 764static int max_connections = 32;
 765
 766static unsigned int live_children;
 767
 768static struct child {
 769        struct child *next;
 770        struct child_process cld;
 771        struct sockaddr_storage address;
 772} *firstborn;
 773
 774static void add_child(struct child_process *cld, struct sockaddr *addr, socklen_t addrlen)
 775{
 776        struct child *newborn, **cradle;
 777
 778        newborn = xcalloc(1, sizeof(*newborn));
 779        live_children++;
 780        memcpy(&newborn->cld, cld, sizeof(*cld));
 781        memcpy(&newborn->address, addr, addrlen);
 782        for (cradle = &firstborn; *cradle; cradle = &(*cradle)->next)
 783                if (!addrcmp(&(*cradle)->address, &newborn->address))
 784                        break;
 785        newborn->next = *cradle;
 786        *cradle = newborn;
 787}
 788
 789/*
 790 * This gets called if the number of connections grows
 791 * past "max_connections".
 792 *
 793 * We kill the newest connection from a duplicate IP.
 794 */
 795static void kill_some_child(void)
 796{
 797        const struct child *blanket, *next;
 798
 799        if (!(blanket = firstborn))
 800                return;
 801
 802        for (; (next = blanket->next); blanket = next)
 803                if (!addrcmp(&blanket->address, &next->address)) {
 804                        kill(blanket->cld.pid, SIGTERM);
 805                        break;
 806                }
 807}
 808
 809static void check_dead_children(void)
 810{
 811        int status;
 812        pid_t pid;
 813
 814        struct child **cradle, *blanket;
 815        for (cradle = &firstborn; (blanket = *cradle);)
 816                if ((pid = waitpid(blanket->cld.pid, &status, WNOHANG)) > 1) {
 817                        const char *dead = "";
 818                        if (status)
 819                                dead = " (with error)";
 820                        loginfo("[%"PRIuMAX"] Disconnected%s", (uintmax_t)pid, dead);
 821
 822                        /* remove the child */
 823                        *cradle = blanket->next;
 824                        live_children--;
 825                        child_process_clear(&blanket->cld);
 826                        free(blanket);
 827                } else
 828                        cradle = &blanket->next;
 829}
 830
 831static struct argv_array cld_argv = ARGV_ARRAY_INIT;
 832static void handle(int incoming, struct sockaddr *addr, socklen_t addrlen)
 833{
 834        struct child_process cld = CHILD_PROCESS_INIT;
 835
 836        if (max_connections && live_children >= max_connections) {
 837                kill_some_child();
 838                sleep(1);  /* give it some time to die */
 839                check_dead_children();
 840                if (live_children >= max_connections) {
 841                        close(incoming);
 842                        logerror("Too many children, dropping connection");
 843                        return;
 844                }
 845        }
 846
 847        if (addr->sa_family == AF_INET) {
 848                char buf[128] = "";
 849                struct sockaddr_in *sin_addr = (void *) addr;
 850                inet_ntop(addr->sa_family, &sin_addr->sin_addr, buf, sizeof(buf));
 851                argv_array_pushf(&cld.env_array, "REMOTE_ADDR=%s", buf);
 852                argv_array_pushf(&cld.env_array, "REMOTE_PORT=%d",
 853                                 ntohs(sin_addr->sin_port));
 854#ifndef NO_IPV6
 855        } else if (addr->sa_family == AF_INET6) {
 856                char buf[128] = "";
 857                struct sockaddr_in6 *sin6_addr = (void *) addr;
 858                inet_ntop(AF_INET6, &sin6_addr->sin6_addr, buf, sizeof(buf));
 859                argv_array_pushf(&cld.env_array, "REMOTE_ADDR=[%s]", buf);
 860                argv_array_pushf(&cld.env_array, "REMOTE_PORT=%d",
 861                                 ntohs(sin6_addr->sin6_port));
 862#endif
 863        }
 864
 865        cld.argv = cld_argv.argv;
 866        cld.in = incoming;
 867        cld.out = dup(incoming);
 868
 869        if (start_command(&cld))
 870                logerror("unable to fork");
 871        else
 872                add_child(&cld, addr, addrlen);
 873}
 874
 875static void child_handler(int signo)
 876{
 877        /*
 878         * Otherwise empty handler because systemcalls will get interrupted
 879         * upon signal receipt
 880         * SysV needs the handler to be rearmed
 881         */
 882        signal(SIGCHLD, child_handler);
 883}
 884
 885static int set_reuse_addr(int sockfd)
 886{
 887        int on = 1;
 888
 889        if (!reuseaddr)
 890                return 0;
 891        return setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
 892                          &on, sizeof(on));
 893}
 894
 895struct socketlist {
 896        int *list;
 897        size_t nr;
 898        size_t alloc;
 899};
 900
 901static const char *ip2str(int family, struct sockaddr *sin, socklen_t len)
 902{
 903#ifdef NO_IPV6
 904        static char ip[INET_ADDRSTRLEN];
 905#else
 906        static char ip[INET6_ADDRSTRLEN];
 907#endif
 908
 909        switch (family) {
 910#ifndef NO_IPV6
 911        case AF_INET6:
 912                inet_ntop(family, &((struct sockaddr_in6*)sin)->sin6_addr, ip, len);
 913                break;
 914#endif
 915        case AF_INET:
 916                inet_ntop(family, &((struct sockaddr_in*)sin)->sin_addr, ip, len);
 917                break;
 918        default:
 919                xsnprintf(ip, sizeof(ip), "<unknown>");
 920        }
 921        return ip;
 922}
 923
 924#ifndef NO_IPV6
 925
 926static int setup_named_sock(char *listen_addr, int listen_port, struct socketlist *socklist)
 927{
 928        int socknum = 0;
 929        char pbuf[NI_MAXSERV];
 930        struct addrinfo hints, *ai0, *ai;
 931        int gai;
 932        long flags;
 933
 934        xsnprintf(pbuf, sizeof(pbuf), "%d", listen_port);
 935        memset(&hints, 0, sizeof(hints));
 936        hints.ai_family = AF_UNSPEC;
 937        hints.ai_socktype = SOCK_STREAM;
 938        hints.ai_protocol = IPPROTO_TCP;
 939        hints.ai_flags = AI_PASSIVE;
 940
 941        gai = getaddrinfo(listen_addr, pbuf, &hints, &ai0);
 942        if (gai) {
 943                logerror("getaddrinfo() for %s failed: %s", listen_addr, gai_strerror(gai));
 944                return 0;
 945        }
 946
 947        for (ai = ai0; ai; ai = ai->ai_next) {
 948                int sockfd;
 949
 950                sockfd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
 951                if (sockfd < 0)
 952                        continue;
 953                if (sockfd >= FD_SETSIZE) {
 954                        logerror("Socket descriptor too large");
 955                        close(sockfd);
 956                        continue;
 957                }
 958
 959#ifdef IPV6_V6ONLY
 960                if (ai->ai_family == AF_INET6) {
 961                        int on = 1;
 962                        setsockopt(sockfd, IPPROTO_IPV6, IPV6_V6ONLY,
 963                                   &on, sizeof(on));
 964                        /* Note: error is not fatal */
 965                }
 966#endif
 967
 968                if (set_reuse_addr(sockfd)) {
 969                        logerror("Could not set SO_REUSEADDR: %s", strerror(errno));
 970                        close(sockfd);
 971                        continue;
 972                }
 973
 974                set_keep_alive(sockfd);
 975
 976                if (bind(sockfd, ai->ai_addr, ai->ai_addrlen) < 0) {
 977                        logerror("Could not bind to %s: %s",
 978                                 ip2str(ai->ai_family, ai->ai_addr, ai->ai_addrlen),
 979                                 strerror(errno));
 980                        close(sockfd);
 981                        continue;       /* not fatal */
 982                }
 983                if (listen(sockfd, 5) < 0) {
 984                        logerror("Could not listen to %s: %s",
 985                                 ip2str(ai->ai_family, ai->ai_addr, ai->ai_addrlen),
 986                                 strerror(errno));
 987                        close(sockfd);
 988                        continue;       /* not fatal */
 989                }
 990
 991                flags = fcntl(sockfd, F_GETFD, 0);
 992                if (flags >= 0)
 993                        fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
 994
 995                ALLOC_GROW(socklist->list, socklist->nr + 1, socklist->alloc);
 996                socklist->list[socklist->nr++] = sockfd;
 997                socknum++;
 998        }
 999
1000        freeaddrinfo(ai0);
1001
1002        return socknum;
1003}
1004
1005#else /* NO_IPV6 */
1006
1007static int setup_named_sock(char *listen_addr, int listen_port, struct socketlist *socklist)
1008{
1009        struct sockaddr_in sin;
1010        int sockfd;
1011        long flags;
1012
1013        memset(&sin, 0, sizeof sin);
1014        sin.sin_family = AF_INET;
1015        sin.sin_port = htons(listen_port);
1016
1017        if (listen_addr) {
1018                /* Well, host better be an IP address here. */
1019                if (inet_pton(AF_INET, listen_addr, &sin.sin_addr.s_addr) <= 0)
1020                        return 0;
1021        } else {
1022                sin.sin_addr.s_addr = htonl(INADDR_ANY);
1023        }
1024
1025        sockfd = socket(AF_INET, SOCK_STREAM, 0);
1026        if (sockfd < 0)
1027                return 0;
1028
1029        if (set_reuse_addr(sockfd)) {
1030                logerror("Could not set SO_REUSEADDR: %s", strerror(errno));
1031                close(sockfd);
1032                return 0;
1033        }
1034
1035        set_keep_alive(sockfd);
1036
1037        if ( bind(sockfd, (struct sockaddr *)&sin, sizeof sin) < 0 ) {
1038                logerror("Could not bind to %s: %s",
1039                         ip2str(AF_INET, (struct sockaddr *)&sin, sizeof(sin)),
1040                         strerror(errno));
1041                close(sockfd);
1042                return 0;
1043        }
1044
1045        if (listen(sockfd, 5) < 0) {
1046                logerror("Could not listen to %s: %s",
1047                         ip2str(AF_INET, (struct sockaddr *)&sin, sizeof(sin)),
1048                         strerror(errno));
1049                close(sockfd);
1050                return 0;
1051        }
1052
1053        flags = fcntl(sockfd, F_GETFD, 0);
1054        if (flags >= 0)
1055                fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
1056
1057        ALLOC_GROW(socklist->list, socklist->nr + 1, socklist->alloc);
1058        socklist->list[socklist->nr++] = sockfd;
1059        return 1;
1060}
1061
1062#endif
1063
1064static void socksetup(struct string_list *listen_addr, int listen_port, struct socketlist *socklist)
1065{
1066        if (!listen_addr->nr)
1067                setup_named_sock(NULL, listen_port, socklist);
1068        else {
1069                int i, socknum;
1070                for (i = 0; i < listen_addr->nr; i++) {
1071                        socknum = setup_named_sock(listen_addr->items[i].string,
1072                                                   listen_port, socklist);
1073
1074                        if (socknum == 0)
1075                                logerror("unable to allocate any listen sockets for host %s on port %u",
1076                                         listen_addr->items[i].string, listen_port);
1077                }
1078        }
1079}
1080
1081static int service_loop(struct socketlist *socklist)
1082{
1083        struct pollfd *pfd;
1084        int i;
1085
1086        pfd = xcalloc(socklist->nr, sizeof(struct pollfd));
1087
1088        for (i = 0; i < socklist->nr; i++) {
1089                pfd[i].fd = socklist->list[i];
1090                pfd[i].events = POLLIN;
1091        }
1092
1093        signal(SIGCHLD, child_handler);
1094
1095        for (;;) {
1096                int i;
1097
1098                check_dead_children();
1099
1100                if (poll(pfd, socklist->nr, -1) < 0) {
1101                        if (errno != EINTR) {
1102                                logerror("Poll failed, resuming: %s",
1103                                      strerror(errno));
1104                                sleep(1);
1105                        }
1106                        continue;
1107                }
1108
1109                for (i = 0; i < socklist->nr; i++) {
1110                        if (pfd[i].revents & POLLIN) {
1111                                union {
1112                                        struct sockaddr sa;
1113                                        struct sockaddr_in sai;
1114#ifndef NO_IPV6
1115                                        struct sockaddr_in6 sai6;
1116#endif
1117                                } ss;
1118                                socklen_t sslen = sizeof(ss);
1119                                int incoming = accept(pfd[i].fd, &ss.sa, &sslen);
1120                                if (incoming < 0) {
1121                                        switch (errno) {
1122                                        case EAGAIN:
1123                                        case EINTR:
1124                                        case ECONNABORTED:
1125                                                continue;
1126                                        default:
1127                                                die_errno("accept returned");
1128                                        }
1129                                }
1130                                handle(incoming, &ss.sa, sslen);
1131                        }
1132                }
1133        }
1134}
1135
1136#ifdef NO_POSIX_GOODIES
1137
1138struct credentials;
1139
1140static void drop_privileges(struct credentials *cred)
1141{
1142        /* nothing */
1143}
1144
1145static struct credentials *prepare_credentials(const char *user_name,
1146    const char *group_name)
1147{
1148        die("--user not supported on this platform");
1149}
1150
1151#else
1152
1153struct credentials {
1154        struct passwd *pass;
1155        gid_t gid;
1156};
1157
1158static void drop_privileges(struct credentials *cred)
1159{
1160        if (cred && (initgroups(cred->pass->pw_name, cred->gid) ||
1161            setgid (cred->gid) || setuid(cred->pass->pw_uid)))
1162                die("cannot drop privileges");
1163}
1164
1165static struct credentials *prepare_credentials(const char *user_name,
1166    const char *group_name)
1167{
1168        static struct credentials c;
1169
1170        c.pass = getpwnam(user_name);
1171        if (!c.pass)
1172                die("user not found - %s", user_name);
1173
1174        if (!group_name)
1175                c.gid = c.pass->pw_gid;
1176        else {
1177                struct group *group = getgrnam(group_name);
1178                if (!group)
1179                        die("group not found - %s", group_name);
1180
1181                c.gid = group->gr_gid;
1182        }
1183
1184        return &c;
1185}
1186#endif
1187
1188static int serve(struct string_list *listen_addr, int listen_port,
1189    struct credentials *cred)
1190{
1191        struct socketlist socklist = { NULL, 0, 0 };
1192
1193        socksetup(listen_addr, listen_port, &socklist);
1194        if (socklist.nr == 0)
1195                die("unable to allocate any listen sockets on port %u",
1196                    listen_port);
1197
1198        drop_privileges(cred);
1199
1200        loginfo("Ready to rumble");
1201
1202        return service_loop(&socklist);
1203}
1204
1205int cmd_main(int argc, const char **argv)
1206{
1207        int listen_port = 0;
1208        struct string_list listen_addr = STRING_LIST_INIT_NODUP;
1209        int serve_mode = 0, inetd_mode = 0;
1210        const char *pid_file = NULL, *user_name = NULL, *group_name = NULL;
1211        int detach = 0;
1212        struct credentials *cred = NULL;
1213        int i;
1214
1215        for (i = 1; i < argc; i++) {
1216                const char *arg = argv[i];
1217                const char *v;
1218
1219                if (skip_prefix(arg, "--listen=", &v)) {
1220                        string_list_append(&listen_addr, xstrdup_tolower(v));
1221                        continue;
1222                }
1223                if (skip_prefix(arg, "--port=", &v)) {
1224                        char *end;
1225                        unsigned long n;
1226                        n = strtoul(v, &end, 0);
1227                        if (*v && !*end) {
1228                                listen_port = n;
1229                                continue;
1230                        }
1231                }
1232                if (!strcmp(arg, "--serve")) {
1233                        serve_mode = 1;
1234                        continue;
1235                }
1236                if (!strcmp(arg, "--inetd")) {
1237                        inetd_mode = 1;
1238                        log_syslog = 1;
1239                        continue;
1240                }
1241                if (!strcmp(arg, "--verbose")) {
1242                        verbose = 1;
1243                        continue;
1244                }
1245                if (!strcmp(arg, "--syslog")) {
1246                        log_syslog = 1;
1247                        continue;
1248                }
1249                if (!strcmp(arg, "--export-all")) {
1250                        export_all_trees = 1;
1251                        continue;
1252                }
1253                if (skip_prefix(arg, "--access-hook=", &v)) {
1254                        access_hook = v;
1255                        continue;
1256                }
1257                if (skip_prefix(arg, "--timeout=", &v)) {
1258                        timeout = atoi(v);
1259                        continue;
1260                }
1261                if (skip_prefix(arg, "--init-timeout=", &v)) {
1262                        init_timeout = atoi(v);
1263                        continue;
1264                }
1265                if (skip_prefix(arg, "--max-connections=", &v)) {
1266                        max_connections = atoi(v);
1267                        if (max_connections < 0)
1268                                max_connections = 0;            /* unlimited */
1269                        continue;
1270                }
1271                if (!strcmp(arg, "--strict-paths")) {
1272                        strict_paths = 1;
1273                        continue;
1274                }
1275                if (skip_prefix(arg, "--base-path=", &v)) {
1276                        base_path = v;
1277                        continue;
1278                }
1279                if (!strcmp(arg, "--base-path-relaxed")) {
1280                        base_path_relaxed = 1;
1281                        continue;
1282                }
1283                if (skip_prefix(arg, "--interpolated-path=", &v)) {
1284                        interpolated_path = v;
1285                        continue;
1286                }
1287                if (!strcmp(arg, "--reuseaddr")) {
1288                        reuseaddr = 1;
1289                        continue;
1290                }
1291                if (!strcmp(arg, "--user-path")) {
1292                        user_path = "";
1293                        continue;
1294                }
1295                if (skip_prefix(arg, "--user-path=", &v)) {
1296                        user_path = v;
1297                        continue;
1298                }
1299                if (skip_prefix(arg, "--pid-file=", &v)) {
1300                        pid_file = v;
1301                        continue;
1302                }
1303                if (!strcmp(arg, "--detach")) {
1304                        detach = 1;
1305                        log_syslog = 1;
1306                        continue;
1307                }
1308                if (skip_prefix(arg, "--user=", &v)) {
1309                        user_name = v;
1310                        continue;
1311                }
1312                if (skip_prefix(arg, "--group=", &v)) {
1313                        group_name = v;
1314                        continue;
1315                }
1316                if (skip_prefix(arg, "--enable=", &v)) {
1317                        enable_service(v, 1);
1318                        continue;
1319                }
1320                if (skip_prefix(arg, "--disable=", &v)) {
1321                        enable_service(v, 0);
1322                        continue;
1323                }
1324                if (skip_prefix(arg, "--allow-override=", &v)) {
1325                        make_service_overridable(v, 1);
1326                        continue;
1327                }
1328                if (skip_prefix(arg, "--forbid-override=", &v)) {
1329                        make_service_overridable(v, 0);
1330                        continue;
1331                }
1332                if (!strcmp(arg, "--informative-errors")) {
1333                        informative_errors = 1;
1334                        continue;
1335                }
1336                if (!strcmp(arg, "--no-informative-errors")) {
1337                        informative_errors = 0;
1338                        continue;
1339                }
1340                if (!strcmp(arg, "--")) {
1341                        ok_paths = &argv[i+1];
1342                        break;
1343                } else if (arg[0] != '-') {
1344                        ok_paths = &argv[i];
1345                        break;
1346                }
1347
1348                usage(daemon_usage);
1349        }
1350
1351        if (log_syslog) {
1352                openlog("git-daemon", LOG_PID, LOG_DAEMON);
1353                set_die_routine(daemon_die);
1354        } else
1355                /* avoid splitting a message in the middle */
1356                setvbuf(stderr, NULL, _IOFBF, 4096);
1357
1358        if (inetd_mode && (detach || group_name || user_name))
1359                die("--detach, --user and --group are incompatible with --inetd");
1360
1361        if (inetd_mode && (listen_port || (listen_addr.nr > 0)))
1362                die("--listen= and --port= are incompatible with --inetd");
1363        else if (listen_port == 0)
1364                listen_port = DEFAULT_GIT_PORT;
1365
1366        if (group_name && !user_name)
1367                die("--group supplied without --user");
1368
1369        if (user_name)
1370                cred = prepare_credentials(user_name, group_name);
1371
1372        if (strict_paths && (!ok_paths || !*ok_paths))
1373                die("option --strict-paths requires a whitelist");
1374
1375        if (base_path && !is_directory(base_path))
1376                die("base-path '%s' does not exist or is not a directory",
1377                    base_path);
1378
1379        if (inetd_mode) {
1380                if (!freopen("/dev/null", "w", stderr))
1381                        die_errno("failed to redirect stderr to /dev/null");
1382        }
1383
1384        if (inetd_mode || serve_mode)
1385                return execute();
1386
1387        if (detach) {
1388                if (daemonize())
1389                        die("--detach not supported on this platform");
1390        }
1391
1392        if (pid_file)
1393                write_file(pid_file, "%"PRIuMAX, (uintmax_t) getpid());
1394
1395        /* prepare argv for serving-processes */
1396        argv_array_push(&cld_argv, argv[0]); /* git-daemon */
1397        argv_array_push(&cld_argv, "--serve");
1398        for (i = 1; i < argc; ++i)
1399                argv_array_push(&cld_argv, argv[i]);
1400
1401        return serve(&listen_addr, listen_port, cred);
1402}