Andrew's git / gitweb.git / daemon.c
?
daemon.con commit Git 2.16-rc1 (36438dc)
   1#include "cache.h"
   2#include "config.h"
   3#include "pkt-line.h"
   4#include "run-command.h"
   5#include "strbuf.h"
   6#include "string-list.h"
   7
   8#ifdef NO_INITGROUPS
   9#define initgroups(x, y) (0) /* nothing */
  10#endif
  11
  12static int log_syslog;
  13static int verbose;
  14static int reuseaddr;
  15static int informative_errors;
  16
  17static const char daemon_usage[] =
  18"git daemon [--verbose] [--syslog] [--export-all]\n"
  19"           [--timeout=<n>] [--init-timeout=<n>] [--max-connections=<n>]\n"
  20"           [--strict-paths] [--base-path=<path>] [--base-path-relaxed]\n"
  21"           [--user-path | --user-path=<path>]\n"
  22"           [--interpolated-path=<path>]\n"
  23"           [--reuseaddr] [--pid-file=<file>]\n"
  24"           [--(enable|disable|allow-override|forbid-override)=<service>]\n"
  25"           [--access-hook=<path>]\n"
  26"           [--inetd | [--listen=<host_or_ipaddr>] [--port=<n>]\n"
  27"                      [--detach] [--user=<user> [--group=<group>]]\n"
  28"           [<directory>...]";
  29
  30/* List of acceptable pathname prefixes */
  31static const char **ok_paths;
  32static int strict_paths;
  33
  34/* If this is set, git-daemon-export-ok is not required */
  35static int export_all_trees;
  36
  37/* Take all paths relative to this one if non-NULL */
  38static const char *base_path;
  39static const char *interpolated_path;
  40static int base_path_relaxed;
  41
  42/* If defined, ~user notation is allowed and the string is inserted
  43 * after ~user/.  E.g. a request to git://host/~alice/frotz would
  44 * go to /home/alice/pub_git/frotz with --user-path=pub_git.
  45 */
  46static const char *user_path;
  47
  48/* Timeout, and initial timeout */
  49static unsigned int timeout;
  50static unsigned int init_timeout;
  51
  52struct hostinfo {
  53        struct strbuf hostname;
  54        struct strbuf canon_hostname;
  55        struct strbuf ip_address;
  56        struct strbuf tcp_port;
  57        unsigned int hostname_lookup_done:1;
  58        unsigned int saw_extended_args:1;
  59};
  60
  61static void lookup_hostname(struct hostinfo *hi);
  62
  63static const char *get_canon_hostname(struct hostinfo *hi)
  64{
  65        lookup_hostname(hi);
  66        return hi->canon_hostname.buf;
  67}
  68
  69static const char *get_ip_address(struct hostinfo *hi)
  70{
  71        lookup_hostname(hi);
  72        return hi->ip_address.buf;
  73}
  74
  75static void logreport(int priority, const char *err, va_list params)
  76{
  77        if (log_syslog) {
  78                char buf[1024];
  79                vsnprintf(buf, sizeof(buf), err, params);
  80                syslog(priority, "%s", buf);
  81        } else {
  82                /*
  83                 * Since stderr is set to buffered mode, the
  84                 * logging of different processes will not overlap
  85                 * unless they overflow the (rather big) buffers.
  86                 */
  87                fprintf(stderr, "[%"PRIuMAX"] ", (uintmax_t)getpid());
  88                vfprintf(stderr, err, params);
  89                fputc('\n', stderr);
  90                fflush(stderr);
  91        }
  92}
  93
  94__attribute__((format (printf, 1, 2)))
  95static void logerror(const char *err, ...)
  96{
  97        va_list params;
  98        va_start(params, err);
  99        logreport(LOG_ERR, err, params);
 100        va_end(params);
 101}
 102
 103__attribute__((format (printf, 1, 2)))
 104static void loginfo(const char *err, ...)
 105{
 106        va_list params;
 107        if (!verbose)
 108                return;
 109        va_start(params, err);
 110        logreport(LOG_INFO, err, params);
 111        va_end(params);
 112}
 113
 114static void NORETURN daemon_die(const char *err, va_list params)
 115{
 116        logreport(LOG_ERR, err, params);
 117        exit(1);
 118}
 119
 120struct expand_path_context {
 121        const char *directory;
 122        struct hostinfo *hostinfo;
 123};
 124
 125static size_t expand_path(struct strbuf *sb, const char *placeholder, void *ctx)
 126{
 127        struct expand_path_context *context = ctx;
 128        struct hostinfo *hi = context->hostinfo;
 129
 130        switch (placeholder[0]) {
 131        case 'H':
 132                strbuf_addbuf(sb, &hi->hostname);
 133                return 1;
 134        case 'C':
 135                if (placeholder[1] == 'H') {
 136                        strbuf_addstr(sb, get_canon_hostname(hi));
 137                        return 2;
 138                }
 139                break;
 140        case 'I':
 141                if (placeholder[1] == 'P') {
 142                        strbuf_addstr(sb, get_ip_address(hi));
 143                        return 2;
 144                }
 145                break;
 146        case 'P':
 147                strbuf_addbuf(sb, &hi->tcp_port);
 148                return 1;
 149        case 'D':
 150                strbuf_addstr(sb, context->directory);
 151                return 1;
 152        }
 153        return 0;
 154}
 155
 156static const char *path_ok(const char *directory, struct hostinfo *hi)
 157{
 158        static char rpath[PATH_MAX];
 159        static char interp_path[PATH_MAX];
 160        size_t rlen;
 161        const char *path;
 162        const char *dir;
 163
 164        dir = directory;
 165
 166        if (daemon_avoid_alias(dir)) {
 167                logerror("'%s': aliased", dir);
 168                return NULL;
 169        }
 170
 171        if (*dir == '~') {
 172                if (!user_path) {
 173                        logerror("'%s': User-path not allowed", dir);
 174                        return NULL;
 175                }
 176                if (*user_path) {
 177                        /* Got either "~alice" or "~alice/foo";
 178                         * rewrite them to "~alice/%s" or
 179                         * "~alice/%s/foo".
 180                         */
 181                        int namlen, restlen = strlen(dir);
 182                        const char *slash = strchr(dir, '/');
 183                        if (!slash)
 184                                slash = dir + restlen;
 185                        namlen = slash - dir;
 186                        restlen -= namlen;
 187                        loginfo("userpath <%s>, request <%s>, namlen %d, restlen %d, slash <%s>", user_path, dir, namlen, restlen, slash);
 188                        rlen = snprintf(rpath, sizeof(rpath), "%.*s/%s%.*s",
 189                                        namlen, dir, user_path, restlen, slash);
 190                        if (rlen >= sizeof(rpath)) {
 191                                logerror("user-path too large: %s", rpath);
 192                                return NULL;
 193                        }
 194                        dir = rpath;
 195                }
 196        }
 197        else if (interpolated_path && hi->saw_extended_args) {
 198                struct strbuf expanded_path = STRBUF_INIT;
 199                struct expand_path_context context;
 200
 201                context.directory = directory;
 202                context.hostinfo = hi;
 203
 204                if (*dir != '/') {
 205                        /* Allow only absolute */
 206                        logerror("'%s': Non-absolute path denied (interpolated-path active)", dir);
 207                        return NULL;
 208                }
 209
 210                strbuf_expand(&expanded_path, interpolated_path,
 211                              expand_path, &context);
 212
 213                rlen = strlcpy(interp_path, expanded_path.buf,
 214                               sizeof(interp_path));
 215                if (rlen >= sizeof(interp_path)) {
 216                        logerror("interpolated path too large: %s",
 217                                 interp_path);
 218                        return NULL;
 219                }
 220
 221                strbuf_release(&expanded_path);
 222                loginfo("Interpolated dir '%s'", interp_path);
 223
 224                dir = interp_path;
 225        }
 226        else if (base_path) {
 227                if (*dir != '/') {
 228                        /* Allow only absolute */
 229                        logerror("'%s': Non-absolute path denied (base-path active)", dir);
 230                        return NULL;
 231                }
 232                rlen = snprintf(rpath, sizeof(rpath), "%s%s", base_path, dir);
 233                if (rlen >= sizeof(rpath)) {
 234                        logerror("base-path too large: %s", rpath);
 235                        return NULL;
 236                }
 237                dir = rpath;
 238        }
 239
 240        path = enter_repo(dir, strict_paths);
 241        if (!path && base_path && base_path_relaxed) {
 242                /*
 243                 * if we fail and base_path_relaxed is enabled, try without
 244                 * prefixing the base path
 245                 */
 246                dir = directory;
 247                path = enter_repo(dir, strict_paths);
 248        }
 249
 250        if (!path) {
 251                logerror("'%s' does not appear to be a git repository", dir);
 252                return NULL;
 253        }
 254
 255        if ( ok_paths && *ok_paths ) {
 256                const char **pp;
 257                int pathlen = strlen(path);
 258
 259                /* The validation is done on the paths after enter_repo
 260                 * appends optional {.git,.git/.git} and friends, but
 261                 * it does not use getcwd().  So if your /pub is
 262                 * a symlink to /mnt/pub, you can whitelist /pub and
 263                 * do not have to say /mnt/pub.
 264                 * Do not say /pub/.
 265                 */
 266                for ( pp = ok_paths ; *pp ; pp++ ) {
 267                        int len = strlen(*pp);
 268                        if (len <= pathlen &&
 269                            !memcmp(*pp, path, len) &&
 270                            (path[len] == '\0' ||
 271                             (!strict_paths && path[len] == '/')))
 272                                return path;
 273                }
 274        }
 275        else {
 276                /* be backwards compatible */
 277                if (!strict_paths)
 278                        return path;
 279        }
 280
 281        logerror("'%s': not in whitelist", path);
 282        return NULL;            /* Fallthrough. Deny by default */
 283}
 284
 285typedef int (*daemon_service_fn)(const struct argv_array *env);
 286struct daemon_service {
 287        const char *name;
 288        const char *config_name;
 289        daemon_service_fn fn;
 290        int enabled;
 291        int overridable;
 292};
 293
 294static int daemon_error(const char *dir, const char *msg)
 295{
 296        if (!informative_errors)
 297                msg = "access denied or repository not exported";
 298        packet_write_fmt(1, "ERR %s: %s", msg, dir);
 299        return -1;
 300}
 301
 302static const char *access_hook;
 303
 304static int run_access_hook(struct daemon_service *service, const char *dir,
 305                           const char *path, struct hostinfo *hi)
 306{
 307        struct child_process child = CHILD_PROCESS_INIT;
 308        struct strbuf buf = STRBUF_INIT;
 309        const char *argv[8];
 310        const char **arg = argv;
 311        char *eol;
 312        int seen_errors = 0;
 313
 314        *arg++ = access_hook;
 315        *arg++ = service->name;
 316        *arg++ = path;
 317        *arg++ = hi->hostname.buf;
 318        *arg++ = get_canon_hostname(hi);
 319        *arg++ = get_ip_address(hi);
 320        *arg++ = hi->tcp_port.buf;
 321        *arg = NULL;
 322
 323        child.use_shell = 1;
 324        child.argv = argv;
 325        child.no_stdin = 1;
 326        child.no_stderr = 1;
 327        child.out = -1;
 328        if (start_command(&child)) {
 329                logerror("daemon access hook '%s' failed to start",
 330                         access_hook);
 331                goto error_return;
 332        }
 333        if (strbuf_read(&buf, child.out, 0) < 0) {
 334                logerror("failed to read from pipe to daemon access hook '%s'",
 335                         access_hook);
 336                strbuf_reset(&buf);
 337                seen_errors = 1;
 338        }
 339        if (close(child.out) < 0) {
 340                logerror("failed to close pipe to daemon access hook '%s'",
 341                         access_hook);
 342                seen_errors = 1;
 343        }
 344        if (finish_command(&child))
 345                seen_errors = 1;
 346
 347        if (!seen_errors) {
 348                strbuf_release(&buf);
 349                return 0;
 350        }
 351
 352error_return:
 353        strbuf_ltrim(&buf);
 354        if (!buf.len)
 355                strbuf_addstr(&buf, "service rejected");
 356        eol = strchr(buf.buf, '\n');
 357        if (eol)
 358                *eol = '\0';
 359        errno = EACCES;
 360        daemon_error(dir, buf.buf);
 361        strbuf_release(&buf);
 362        return -1;
 363}
 364
 365static int run_service(const char *dir, struct daemon_service *service,
 366                       struct hostinfo *hi, const struct argv_array *env)
 367{
 368        const char *path;
 369        int enabled = service->enabled;
 370        struct strbuf var = STRBUF_INIT;
 371
 372        loginfo("Request %s for '%s'", service->name, dir);
 373
 374        if (!enabled && !service->overridable) {
 375                logerror("'%s': service not enabled.", service->name);
 376                errno = EACCES;
 377                return daemon_error(dir, "service not enabled");
 378        }
 379
 380        if (!(path = path_ok(dir, hi)))
 381                return daemon_error(dir, "no such repository");
 382
 383        /*
 384         * Security on the cheap.
 385         *
 386         * We want a readable HEAD, usable "objects" directory, and
 387         * a "git-daemon-export-ok" flag that says that the other side
 388         * is ok with us doing this.
 389         *
 390         * path_ok() uses enter_repo() and does whitelist checking.
 391         * We only need to make sure the repository is exported.
 392         */
 393
 394        if (!export_all_trees && access("git-daemon-export-ok", F_OK)) {
 395                logerror("'%s': repository not exported.", path);
 396                errno = EACCES;
 397                return daemon_error(dir, "repository not exported");
 398        }
 399
 400        if (service->overridable) {
 401                strbuf_addf(&var, "daemon.%s", service->config_name);
 402                git_config_get_bool(var.buf, &enabled);
 403                strbuf_release(&var);
 404        }
 405        if (!enabled) {
 406                logerror("'%s': service not enabled for '%s'",
 407                         service->name, path);
 408                errno = EACCES;
 409                return daemon_error(dir, "service not enabled");
 410        }
 411
 412        /*
 413         * Optionally, a hook can choose to deny access to the
 414         * repository depending on the phase of the moon.
 415         */
 416        if (access_hook && run_access_hook(service, dir, path, hi))
 417                return -1;
 418
 419        /*
 420         * We'll ignore SIGTERM from now on, we have a
 421         * good client.
 422         */
 423        signal(SIGTERM, SIG_IGN);
 424
 425        return service->fn(env);
 426}
 427
 428static void copy_to_log(int fd)
 429{
 430        struct strbuf line = STRBUF_INIT;
 431        FILE *fp;
 432
 433        fp = fdopen(fd, "r");
 434        if (fp == NULL) {
 435                logerror("fdopen of error channel failed");
 436                close(fd);
 437                return;
 438        }
 439
 440        while (strbuf_getline_lf(&line, fp) != EOF) {
 441                logerror("%s", line.buf);
 442                strbuf_setlen(&line, 0);
 443        }
 444
 445        strbuf_release(&line);
 446        fclose(fp);
 447}
 448
 449static int run_service_command(struct child_process *cld)
 450{
 451        argv_array_push(&cld->args, ".");
 452        cld->git_cmd = 1;
 453        cld->err = -1;
 454        if (start_command(cld))
 455                return -1;
 456
 457        close(0);
 458        close(1);
 459
 460        copy_to_log(cld->err);
 461
 462        return finish_command(cld);
 463}
 464
 465static int upload_pack(const struct argv_array *env)
 466{
 467        struct child_process cld = CHILD_PROCESS_INIT;
 468        argv_array_pushl(&cld.args, "upload-pack", "--strict", NULL);
 469        argv_array_pushf(&cld.args, "--timeout=%u", timeout);
 470
 471        argv_array_pushv(&cld.env_array, env->argv);
 472
 473        return run_service_command(&cld);
 474}
 475
 476static int upload_archive(const struct argv_array *env)
 477{
 478        struct child_process cld = CHILD_PROCESS_INIT;
 479        argv_array_push(&cld.args, "upload-archive");
 480
 481        argv_array_pushv(&cld.env_array, env->argv);
 482
 483        return run_service_command(&cld);
 484}
 485
 486static int receive_pack(const struct argv_array *env)
 487{
 488        struct child_process cld = CHILD_PROCESS_INIT;
 489        argv_array_push(&cld.args, "receive-pack");
 490
 491        argv_array_pushv(&cld.env_array, env->argv);
 492
 493        return run_service_command(&cld);
 494}
 495
 496static struct daemon_service daemon_service[] = {
 497        { "upload-archive", "uploadarch", upload_archive, 0, 1 },
 498        { "upload-pack", "uploadpack", upload_pack, 1, 1 },
 499        { "receive-pack", "receivepack", receive_pack, 0, 1 },
 500};
 501
 502static void enable_service(const char *name, int ena)
 503{
 504        int i;
 505        for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 506                if (!strcmp(daemon_service[i].name, name)) {
 507                        daemon_service[i].enabled = ena;
 508                        return;
 509                }
 510        }
 511        die("No such service %s", name);
 512}
 513
 514static void make_service_overridable(const char *name, int ena)
 515{
 516        int i;
 517        for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 518                if (!strcmp(daemon_service[i].name, name)) {
 519                        daemon_service[i].overridable = ena;
 520                        return;
 521                }
 522        }
 523        die("No such service %s", name);
 524}
 525
 526static void parse_host_and_port(char *hostport, char **host,
 527        char **port)
 528{
 529        if (*hostport == '[') {
 530                char *end;
 531
 532                end = strchr(hostport, ']');
 533                if (!end)
 534                        die("Invalid request ('[' without ']')");
 535                *end = '\0';
 536                *host = hostport + 1;
 537                if (!end[1])
 538                        *port = NULL;
 539                else if (end[1] == ':')
 540                        *port = end + 2;
 541                else
 542                        die("Garbage after end of host part");
 543        } else {
 544                *host = hostport;
 545                *port = strrchr(hostport, ':');
 546                if (*port) {
 547                        **port = '\0';
 548                        ++*port;
 549                }
 550        }
 551}
 552
 553/*
 554 * Sanitize a string from the client so that it's OK to be inserted into a
 555 * filesystem path. Specifically, we disallow slashes, runs of "..", and
 556 * trailing and leading dots, which means that the client cannot escape
 557 * our base path via ".." traversal.
 558 */
 559static void sanitize_client(struct strbuf *out, const char *in)
 560{
 561        for (; *in; in++) {
 562                if (*in == '/')
 563                        continue;
 564                if (*in == '.' && (!out->len || out->buf[out->len - 1] == '.'))
 565                        continue;
 566                strbuf_addch(out, *in);
 567        }
 568
 569        while (out->len && out->buf[out->len - 1] == '.')
 570                strbuf_setlen(out, out->len - 1);
 571}
 572
 573/*
 574 * Like sanitize_client, but we also perform any canonicalization
 575 * to make life easier on the admin.
 576 */
 577static void canonicalize_client(struct strbuf *out, const char *in)
 578{
 579        sanitize_client(out, in);
 580        strbuf_tolower(out);
 581}
 582
 583/*
 584 * Read the host as supplied by the client connection.
 585 *
 586 * Returns a pointer to the character after the NUL byte terminating the host
 587 * arguemnt, or 'extra_args' if there is no host arguemnt.
 588 */
 589static char *parse_host_arg(struct hostinfo *hi, char *extra_args, int buflen)
 590{
 591        char *val;
 592        int vallen;
 593        char *end = extra_args + buflen;
 594
 595        if (extra_args < end && *extra_args) {
 596                hi->saw_extended_args = 1;
 597                if (strncasecmp("host=", extra_args, 5) == 0) {
 598                        val = extra_args + 5;
 599                        vallen = strlen(val) + 1;
 600                        if (*val) {
 601                                /* Split <host>:<port> at colon. */
 602                                char *host;
 603                                char *port;
 604                                parse_host_and_port(val, &host, &port);
 605                                if (port)
 606                                        sanitize_client(&hi->tcp_port, port);
 607                                canonicalize_client(&hi->hostname, host);
 608                                hi->hostname_lookup_done = 0;
 609                        }
 610
 611                        /* On to the next one */
 612                        extra_args = val + vallen;
 613                }
 614                if (extra_args < end && *extra_args)
 615                        die("Invalid request");
 616        }
 617
 618        return extra_args;
 619}
 620
 621static void parse_extra_args(struct hostinfo *hi, struct argv_array *env,
 622                             char *extra_args, int buflen)
 623{
 624        const char *end = extra_args + buflen;
 625        struct strbuf git_protocol = STRBUF_INIT;
 626
 627        /* First look for the host argument */
 628        extra_args = parse_host_arg(hi, extra_args, buflen);
 629
 630        /* Look for additional arguments places after a second NUL byte */
 631        for (; extra_args < end; extra_args += strlen(extra_args) + 1) {
 632                const char *arg = extra_args;
 633
 634                /*
 635                 * Parse the extra arguments, adding most to 'git_protocol'
 636                 * which will be used to set the 'GIT_PROTOCOL' envvar in the
 637                 * service that will be run.
 638                 *
 639                 * If there ends up being a particular arg in the future that
 640                 * git-daemon needs to parse specificly (like the 'host' arg)
 641                 * then it can be parsed here and not added to 'git_protocol'.
 642                 */
 643                if (*arg) {
 644                        if (git_protocol.len > 0)
 645                                strbuf_addch(&git_protocol, ':');
 646                        strbuf_addstr(&git_protocol, arg);
 647                }
 648        }
 649
 650        if (git_protocol.len > 0)
 651                argv_array_pushf(env, GIT_PROTOCOL_ENVIRONMENT "=%s",
 652                                 git_protocol.buf);
 653        strbuf_release(&git_protocol);
 654}
 655
 656/*
 657 * Locate canonical hostname and its IP address.
 658 */
 659static void lookup_hostname(struct hostinfo *hi)
 660{
 661        if (!hi->hostname_lookup_done && hi->hostname.len) {
 662#ifndef NO_IPV6
 663                struct addrinfo hints;
 664                struct addrinfo *ai;
 665                int gai;
 666                static char addrbuf[HOST_NAME_MAX + 1];
 667
 668                memset(&hints, 0, sizeof(hints));
 669                hints.ai_flags = AI_CANONNAME;
 670
 671                gai = getaddrinfo(hi->hostname.buf, NULL, &hints, &ai);
 672                if (!gai) {
 673                        struct sockaddr_in *sin_addr = (void *)ai->ai_addr;
 674
 675                        inet_ntop(AF_INET, &sin_addr->sin_addr,
 676                                  addrbuf, sizeof(addrbuf));
 677                        strbuf_addstr(&hi->ip_address, addrbuf);
 678
 679                        if (ai->ai_canonname)
 680                                sanitize_client(&hi->canon_hostname,
 681                                                ai->ai_canonname);
 682                        else
 683                                strbuf_addbuf(&hi->canon_hostname,
 684                                              &hi->ip_address);
 685
 686                        freeaddrinfo(ai);
 687                }
 688#else
 689                struct hostent *hent;
 690                struct sockaddr_in sa;
 691                char **ap;
 692                static char addrbuf[HOST_NAME_MAX + 1];
 693
 694                hent = gethostbyname(hi->hostname.buf);
 695                if (hent) {
 696                        ap = hent->h_addr_list;
 697                        memset(&sa, 0, sizeof sa);
 698                        sa.sin_family = hent->h_addrtype;
 699                        sa.sin_port = htons(0);
 700                        memcpy(&sa.sin_addr, *ap, hent->h_length);
 701
 702                        inet_ntop(hent->h_addrtype, &sa.sin_addr,
 703                                  addrbuf, sizeof(addrbuf));
 704
 705                        sanitize_client(&hi->canon_hostname, hent->h_name);
 706                        strbuf_addstr(&hi->ip_address, addrbuf);
 707                }
 708#endif
 709                hi->hostname_lookup_done = 1;
 710        }
 711}
 712
 713static void hostinfo_init(struct hostinfo *hi)
 714{
 715        memset(hi, 0, sizeof(*hi));
 716        strbuf_init(&hi->hostname, 0);
 717        strbuf_init(&hi->canon_hostname, 0);
 718        strbuf_init(&hi->ip_address, 0);
 719        strbuf_init(&hi->tcp_port, 0);
 720}
 721
 722static void hostinfo_clear(struct hostinfo *hi)
 723{
 724        strbuf_release(&hi->hostname);
 725        strbuf_release(&hi->canon_hostname);
 726        strbuf_release(&hi->ip_address);
 727        strbuf_release(&hi->tcp_port);
 728}
 729
 730static void set_keep_alive(int sockfd)
 731{
 732        int ka = 1;
 733
 734        if (setsockopt(sockfd, SOL_SOCKET, SO_KEEPALIVE, &ka, sizeof(ka)) < 0) {
 735                if (errno != ENOTSOCK)
 736                        logerror("unable to set SO_KEEPALIVE on socket: %s",
 737                                strerror(errno));
 738        }
 739}
 740
 741static int execute(void)
 742{
 743        char *line = packet_buffer;
 744        int pktlen, len, i;
 745        char *addr = getenv("REMOTE_ADDR"), *port = getenv("REMOTE_PORT");
 746        struct hostinfo hi;
 747        struct argv_array env = ARGV_ARRAY_INIT;
 748
 749        hostinfo_init(&hi);
 750
 751        if (addr)
 752                loginfo("Connection from %s:%s", addr, port);
 753
 754        set_keep_alive(0);
 755        alarm(init_timeout ? init_timeout : timeout);
 756        pktlen = packet_read(0, NULL, NULL, packet_buffer, sizeof(packet_buffer), 0);
 757        alarm(0);
 758
 759        len = strlen(line);
 760        if (pktlen != len)
 761                loginfo("Extended attributes (%d bytes) exist <%.*s>",
 762                        (int) pktlen - len,
 763                        (int) pktlen - len, line + len + 1);
 764        if (len && line[len-1] == '\n') {
 765                line[--len] = 0;
 766                pktlen--;
 767        }
 768
 769        /* parse additional args hidden behind a NUL byte */
 770        if (len != pktlen)
 771                parse_extra_args(&hi, &env, line + len + 1, pktlen - len - 1);
 772
 773        for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 774                struct daemon_service *s = &(daemon_service[i]);
 775                const char *arg;
 776
 777                if (skip_prefix(line, "git-", &arg) &&
 778                    skip_prefix(arg, s->name, &arg) &&
 779                    *arg++ == ' ') {
 780                        /*
 781                         * Note: The directory here is probably context sensitive,
 782                         * and might depend on the actual service being performed.
 783                         */
 784                        int rc = run_service(arg, s, &hi, &env);
 785                        hostinfo_clear(&hi);
 786                        argv_array_clear(&env);
 787                        return rc;
 788                }
 789        }
 790
 791        hostinfo_clear(&hi);
 792        argv_array_clear(&env);
 793        logerror("Protocol error: '%s'", line);
 794        return -1;
 795}
 796
 797static int addrcmp(const struct sockaddr_storage *s1,
 798    const struct sockaddr_storage *s2)
 799{
 800        const struct sockaddr *sa1 = (const struct sockaddr*) s1;
 801        const struct sockaddr *sa2 = (const struct sockaddr*) s2;
 802
 803        if (sa1->sa_family != sa2->sa_family)
 804                return sa1->sa_family - sa2->sa_family;
 805        if (sa1->sa_family == AF_INET)
 806                return memcmp(&((struct sockaddr_in *)s1)->sin_addr,
 807                    &((struct sockaddr_in *)s2)->sin_addr,
 808                    sizeof(struct in_addr));
 809#ifndef NO_IPV6
 810        if (sa1->sa_family == AF_INET6)
 811                return memcmp(&((struct sockaddr_in6 *)s1)->sin6_addr,
 812                    &((struct sockaddr_in6 *)s2)->sin6_addr,
 813                    sizeof(struct in6_addr));
 814#endif
 815        return 0;
 816}
 817
 818static int max_connections = 32;
 819
 820static unsigned int live_children;
 821
 822static struct child {
 823        struct child *next;
 824        struct child_process cld;
 825        struct sockaddr_storage address;
 826} *firstborn;
 827
 828static void add_child(struct child_process *cld, struct sockaddr *addr, socklen_t addrlen)
 829{
 830        struct child *newborn, **cradle;
 831
 832        newborn = xcalloc(1, sizeof(*newborn));
 833        live_children++;
 834        memcpy(&newborn->cld, cld, sizeof(*cld));
 835        memcpy(&newborn->address, addr, addrlen);
 836        for (cradle = &firstborn; *cradle; cradle = &(*cradle)->next)
 837                if (!addrcmp(&(*cradle)->address, &newborn->address))
 838                        break;
 839        newborn->next = *cradle;
 840        *cradle = newborn;
 841}
 842
 843/*
 844 * This gets called if the number of connections grows
 845 * past "max_connections".
 846 *
 847 * We kill the newest connection from a duplicate IP.
 848 */
 849static void kill_some_child(void)
 850{
 851        const struct child *blanket, *next;
 852
 853        if (!(blanket = firstborn))
 854                return;
 855
 856        for (; (next = blanket->next); blanket = next)
 857                if (!addrcmp(&blanket->address, &next->address)) {
 858                        kill(blanket->cld.pid, SIGTERM);
 859                        break;
 860                }
 861}
 862
 863static void check_dead_children(void)
 864{
 865        int status;
 866        pid_t pid;
 867
 868        struct child **cradle, *blanket;
 869        for (cradle = &firstborn; (blanket = *cradle);)
 870                if ((pid = waitpid(blanket->cld.pid, &status, WNOHANG)) > 1) {
 871                        const char *dead = "";
 872                        if (status)
 873                                dead = " (with error)";
 874                        loginfo("[%"PRIuMAX"] Disconnected%s", (uintmax_t)pid, dead);
 875
 876                        /* remove the child */
 877                        *cradle = blanket->next;
 878                        live_children--;
 879                        child_process_clear(&blanket->cld);
 880                        free(blanket);
 881                } else
 882                        cradle = &blanket->next;
 883}
 884
 885static struct argv_array cld_argv = ARGV_ARRAY_INIT;
 886static void handle(int incoming, struct sockaddr *addr, socklen_t addrlen)
 887{
 888        struct child_process cld = CHILD_PROCESS_INIT;
 889
 890        if (max_connections && live_children >= max_connections) {
 891                kill_some_child();
 892                sleep(1);  /* give it some time to die */
 893                check_dead_children();
 894                if (live_children >= max_connections) {
 895                        close(incoming);
 896                        logerror("Too many children, dropping connection");
 897                        return;
 898                }
 899        }
 900
 901        if (addr->sa_family == AF_INET) {
 902                char buf[128] = "";
 903                struct sockaddr_in *sin_addr = (void *) addr;
 904                inet_ntop(addr->sa_family, &sin_addr->sin_addr, buf, sizeof(buf));
 905                argv_array_pushf(&cld.env_array, "REMOTE_ADDR=%s", buf);
 906                argv_array_pushf(&cld.env_array, "REMOTE_PORT=%d",
 907                                 ntohs(sin_addr->sin_port));
 908#ifndef NO_IPV6
 909        } else if (addr->sa_family == AF_INET6) {
 910                char buf[128] = "";
 911                struct sockaddr_in6 *sin6_addr = (void *) addr;
 912                inet_ntop(AF_INET6, &sin6_addr->sin6_addr, buf, sizeof(buf));
 913                argv_array_pushf(&cld.env_array, "REMOTE_ADDR=[%s]", buf);
 914                argv_array_pushf(&cld.env_array, "REMOTE_PORT=%d",
 915                                 ntohs(sin6_addr->sin6_port));
 916#endif
 917        }
 918
 919        cld.argv = cld_argv.argv;
 920        cld.in = incoming;
 921        cld.out = dup(incoming);
 922
 923        if (start_command(&cld))
 924                logerror("unable to fork");
 925        else
 926                add_child(&cld, addr, addrlen);
 927}
 928
 929static void child_handler(int signo)
 930{
 931        /*
 932         * Otherwise empty handler because systemcalls will get interrupted
 933         * upon signal receipt
 934         * SysV needs the handler to be rearmed
 935         */
 936        signal(SIGCHLD, child_handler);
 937}
 938
 939static int set_reuse_addr(int sockfd)
 940{
 941        int on = 1;
 942
 943        if (!reuseaddr)
 944                return 0;
 945        return setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
 946                          &on, sizeof(on));
 947}
 948
 949struct socketlist {
 950        int *list;
 951        size_t nr;
 952        size_t alloc;
 953};
 954
 955static const char *ip2str(int family, struct sockaddr *sin, socklen_t len)
 956{
 957#ifdef NO_IPV6
 958        static char ip[INET_ADDRSTRLEN];
 959#else
 960        static char ip[INET6_ADDRSTRLEN];
 961#endif
 962
 963        switch (family) {
 964#ifndef NO_IPV6
 965        case AF_INET6:
 966                inet_ntop(family, &((struct sockaddr_in6*)sin)->sin6_addr, ip, len);
 967                break;
 968#endif
 969        case AF_INET:
 970                inet_ntop(family, &((struct sockaddr_in*)sin)->sin_addr, ip, len);
 971                break;
 972        default:
 973                xsnprintf(ip, sizeof(ip), "<unknown>");
 974        }
 975        return ip;
 976}
 977
 978#ifndef NO_IPV6
 979
 980static int setup_named_sock(char *listen_addr, int listen_port, struct socketlist *socklist)
 981{
 982        int socknum = 0;
 983        char pbuf[NI_MAXSERV];
 984        struct addrinfo hints, *ai0, *ai;
 985        int gai;
 986        long flags;
 987
 988        xsnprintf(pbuf, sizeof(pbuf), "%d", listen_port);
 989        memset(&hints, 0, sizeof(hints));
 990        hints.ai_family = AF_UNSPEC;
 991        hints.ai_socktype = SOCK_STREAM;
 992        hints.ai_protocol = IPPROTO_TCP;
 993        hints.ai_flags = AI_PASSIVE;
 994
 995        gai = getaddrinfo(listen_addr, pbuf, &hints, &ai0);
 996        if (gai) {
 997                logerror("getaddrinfo() for %s failed: %s", listen_addr, gai_strerror(gai));
 998                return 0;
 999        }
1000
1001        for (ai = ai0; ai; ai = ai->ai_next) {
1002                int sockfd;
1003
1004                sockfd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
1005                if (sockfd < 0)
1006                        continue;
1007                if (sockfd >= FD_SETSIZE) {
1008                        logerror("Socket descriptor too large");
1009                        close(sockfd);
1010                        continue;
1011                }
1012
1013#ifdef IPV6_V6ONLY
1014                if (ai->ai_family == AF_INET6) {
1015                        int on = 1;
1016                        setsockopt(sockfd, IPPROTO_IPV6, IPV6_V6ONLY,
1017                                   &on, sizeof(on));
1018                        /* Note: error is not fatal */
1019                }
1020#endif
1021
1022                if (set_reuse_addr(sockfd)) {
1023                        logerror("Could not set SO_REUSEADDR: %s", strerror(errno));
1024                        close(sockfd);
1025                        continue;
1026                }
1027
1028                set_keep_alive(sockfd);
1029
1030                if (bind(sockfd, ai->ai_addr, ai->ai_addrlen) < 0) {
1031                        logerror("Could not bind to %s: %s",
1032                                 ip2str(ai->ai_family, ai->ai_addr, ai->ai_addrlen),
1033                                 strerror(errno));
1034                        close(sockfd);
1035                        continue;       /* not fatal */
1036                }
1037                if (listen(sockfd, 5) < 0) {
1038                        logerror("Could not listen to %s: %s",
1039                                 ip2str(ai->ai_family, ai->ai_addr, ai->ai_addrlen),
1040                                 strerror(errno));
1041                        close(sockfd);
1042                        continue;       /* not fatal */
1043                }
1044
1045                flags = fcntl(sockfd, F_GETFD, 0);
1046                if (flags >= 0)
1047                        fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
1048
1049                ALLOC_GROW(socklist->list, socklist->nr + 1, socklist->alloc);
1050                socklist->list[socklist->nr++] = sockfd;
1051                socknum++;
1052        }
1053
1054        freeaddrinfo(ai0);
1055
1056        return socknum;
1057}
1058
1059#else /* NO_IPV6 */
1060
1061static int setup_named_sock(char *listen_addr, int listen_port, struct socketlist *socklist)
1062{
1063        struct sockaddr_in sin;
1064        int sockfd;
1065        long flags;
1066
1067        memset(&sin, 0, sizeof sin);
1068        sin.sin_family = AF_INET;
1069        sin.sin_port = htons(listen_port);
1070
1071        if (listen_addr) {
1072                /* Well, host better be an IP address here. */
1073                if (inet_pton(AF_INET, listen_addr, &sin.sin_addr.s_addr) <= 0)
1074                        return 0;
1075        } else {
1076                sin.sin_addr.s_addr = htonl(INADDR_ANY);
1077        }
1078
1079        sockfd = socket(AF_INET, SOCK_STREAM, 0);
1080        if (sockfd < 0)
1081                return 0;
1082
1083        if (set_reuse_addr(sockfd)) {
1084                logerror("Could not set SO_REUSEADDR: %s", strerror(errno));
1085                close(sockfd);
1086                return 0;
1087        }
1088
1089        set_keep_alive(sockfd);
1090
1091        if ( bind(sockfd, (struct sockaddr *)&sin, sizeof sin) < 0 ) {
1092                logerror("Could not bind to %s: %s",
1093                         ip2str(AF_INET, (struct sockaddr *)&sin, sizeof(sin)),
1094                         strerror(errno));
1095                close(sockfd);
1096                return 0;
1097        }
1098
1099        if (listen(sockfd, 5) < 0) {
1100                logerror("Could not listen to %s: %s",
1101                         ip2str(AF_INET, (struct sockaddr *)&sin, sizeof(sin)),
1102                         strerror(errno));
1103                close(sockfd);
1104                return 0;
1105        }
1106
1107        flags = fcntl(sockfd, F_GETFD, 0);
1108        if (flags >= 0)
1109                fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
1110
1111        ALLOC_GROW(socklist->list, socklist->nr + 1, socklist->alloc);
1112        socklist->list[socklist->nr++] = sockfd;
1113        return 1;
1114}
1115
1116#endif
1117
1118static void socksetup(struct string_list *listen_addr, int listen_port, struct socketlist *socklist)
1119{
1120        if (!listen_addr->nr)
1121                setup_named_sock(NULL, listen_port, socklist);
1122        else {
1123                int i, socknum;
1124                for (i = 0; i < listen_addr->nr; i++) {
1125                        socknum = setup_named_sock(listen_addr->items[i].string,
1126                                                   listen_port, socklist);
1127
1128                        if (socknum == 0)
1129                                logerror("unable to allocate any listen sockets for host %s on port %u",
1130                                         listen_addr->items[i].string, listen_port);
1131                }
1132        }
1133}
1134
1135static int service_loop(struct socketlist *socklist)
1136{
1137        struct pollfd *pfd;
1138        int i;
1139
1140        pfd = xcalloc(socklist->nr, sizeof(struct pollfd));
1141
1142        for (i = 0; i < socklist->nr; i++) {
1143                pfd[i].fd = socklist->list[i];
1144                pfd[i].events = POLLIN;
1145        }
1146
1147        signal(SIGCHLD, child_handler);
1148
1149        for (;;) {
1150                int i;
1151
1152                check_dead_children();
1153
1154                if (poll(pfd, socklist->nr, -1) < 0) {
1155                        if (errno != EINTR) {
1156                                logerror("Poll failed, resuming: %s",
1157                                      strerror(errno));
1158                                sleep(1);
1159                        }
1160                        continue;
1161                }
1162
1163                for (i = 0; i < socklist->nr; i++) {
1164                        if (pfd[i].revents & POLLIN) {
1165                                union {
1166                                        struct sockaddr sa;
1167                                        struct sockaddr_in sai;
1168#ifndef NO_IPV6
1169                                        struct sockaddr_in6 sai6;
1170#endif
1171                                } ss;
1172                                socklen_t sslen = sizeof(ss);
1173                                int incoming = accept(pfd[i].fd, &ss.sa, &sslen);
1174                                if (incoming < 0) {
1175                                        switch (errno) {
1176                                        case EAGAIN:
1177                                        case EINTR:
1178                                        case ECONNABORTED:
1179                                                continue;
1180                                        default:
1181                                                die_errno("accept returned");
1182                                        }
1183                                }
1184                                handle(incoming, &ss.sa, sslen);
1185                        }
1186                }
1187        }
1188}
1189
1190#ifdef NO_POSIX_GOODIES
1191
1192struct credentials;
1193
1194static void drop_privileges(struct credentials *cred)
1195{
1196        /* nothing */
1197}
1198
1199static struct credentials *prepare_credentials(const char *user_name,
1200    const char *group_name)
1201{
1202        die("--user not supported on this platform");
1203}
1204
1205#else
1206
1207struct credentials {
1208        struct passwd *pass;
1209        gid_t gid;
1210};
1211
1212static void drop_privileges(struct credentials *cred)
1213{
1214        if (cred && (initgroups(cred->pass->pw_name, cred->gid) ||
1215            setgid (cred->gid) || setuid(cred->pass->pw_uid)))
1216                die("cannot drop privileges");
1217}
1218
1219static struct credentials *prepare_credentials(const char *user_name,
1220    const char *group_name)
1221{
1222        static struct credentials c;
1223
1224        c.pass = getpwnam(user_name);
1225        if (!c.pass)
1226                die("user not found - %s", user_name);
1227
1228        if (!group_name)
1229                c.gid = c.pass->pw_gid;
1230        else {
1231                struct group *group = getgrnam(group_name);
1232                if (!group)
1233                        die("group not found - %s", group_name);
1234
1235                c.gid = group->gr_gid;
1236        }
1237
1238        return &c;
1239}
1240#endif
1241
1242static int serve(struct string_list *listen_addr, int listen_port,
1243    struct credentials *cred)
1244{
1245        struct socketlist socklist = { NULL, 0, 0 };
1246
1247        socksetup(listen_addr, listen_port, &socklist);
1248        if (socklist.nr == 0)
1249                die("unable to allocate any listen sockets on port %u",
1250                    listen_port);
1251
1252        drop_privileges(cred);
1253
1254        loginfo("Ready to rumble");
1255
1256        return service_loop(&socklist);
1257}
1258
1259int cmd_main(int argc, const char **argv)
1260{
1261        int listen_port = 0;
1262        struct string_list listen_addr = STRING_LIST_INIT_NODUP;
1263        int serve_mode = 0, inetd_mode = 0;
1264        const char *pid_file = NULL, *user_name = NULL, *group_name = NULL;
1265        int detach = 0;
1266        struct credentials *cred = NULL;
1267        int i;
1268
1269        for (i = 1; i < argc; i++) {
1270                const char *arg = argv[i];
1271                const char *v;
1272
1273                if (skip_prefix(arg, "--listen=", &v)) {
1274                        string_list_append(&listen_addr, xstrdup_tolower(v));
1275                        continue;
1276                }
1277                if (skip_prefix(arg, "--port=", &v)) {
1278                        char *end;
1279                        unsigned long n;
1280                        n = strtoul(v, &end, 0);
1281                        if (*v && !*end) {
1282                                listen_port = n;
1283                                continue;
1284                        }
1285                }
1286                if (!strcmp(arg, "--serve")) {
1287                        serve_mode = 1;
1288                        continue;
1289                }
1290                if (!strcmp(arg, "--inetd")) {
1291                        inetd_mode = 1;
1292                        log_syslog = 1;
1293                        continue;
1294                }
1295                if (!strcmp(arg, "--verbose")) {
1296                        verbose = 1;
1297                        continue;
1298                }
1299                if (!strcmp(arg, "--syslog")) {
1300                        log_syslog = 1;
1301                        continue;
1302                }
1303                if (!strcmp(arg, "--export-all")) {
1304                        export_all_trees = 1;
1305                        continue;
1306                }
1307                if (skip_prefix(arg, "--access-hook=", &v)) {
1308                        access_hook = v;
1309                        continue;
1310                }
1311                if (skip_prefix(arg, "--timeout=", &v)) {
1312                        timeout = atoi(v);
1313                        continue;
1314                }
1315                if (skip_prefix(arg, "--init-timeout=", &v)) {
1316                        init_timeout = atoi(v);
1317                        continue;
1318                }
1319                if (skip_prefix(arg, "--max-connections=", &v)) {
1320                        max_connections = atoi(v);
1321                        if (max_connections < 0)
1322                                max_connections = 0;            /* unlimited */
1323                        continue;
1324                }
1325                if (!strcmp(arg, "--strict-paths")) {
1326                        strict_paths = 1;
1327                        continue;
1328                }
1329                if (skip_prefix(arg, "--base-path=", &v)) {
1330                        base_path = v;
1331                        continue;
1332                }
1333                if (!strcmp(arg, "--base-path-relaxed")) {
1334                        base_path_relaxed = 1;
1335                        continue;
1336                }
1337                if (skip_prefix(arg, "--interpolated-path=", &v)) {
1338                        interpolated_path = v;
1339                        continue;
1340                }
1341                if (!strcmp(arg, "--reuseaddr")) {
1342                        reuseaddr = 1;
1343                        continue;
1344                }
1345                if (!strcmp(arg, "--user-path")) {
1346                        user_path = "";
1347                        continue;
1348                }
1349                if (skip_prefix(arg, "--user-path=", &v)) {
1350                        user_path = v;
1351                        continue;
1352                }
1353                if (skip_prefix(arg, "--pid-file=", &v)) {
1354                        pid_file = v;
1355                        continue;
1356                }
1357                if (!strcmp(arg, "--detach")) {
1358                        detach = 1;
1359                        log_syslog = 1;
1360                        continue;
1361                }
1362                if (skip_prefix(arg, "--user=", &v)) {
1363                        user_name = v;
1364                        continue;
1365                }
1366                if (skip_prefix(arg, "--group=", &v)) {
1367                        group_name = v;
1368                        continue;
1369                }
1370                if (skip_prefix(arg, "--enable=", &v)) {
1371                        enable_service(v, 1);
1372                        continue;
1373                }
1374                if (skip_prefix(arg, "--disable=", &v)) {
1375                        enable_service(v, 0);
1376                        continue;
1377                }
1378                if (skip_prefix(arg, "--allow-override=", &v)) {
1379                        make_service_overridable(v, 1);
1380                        continue;
1381                }
1382                if (skip_prefix(arg, "--forbid-override=", &v)) {
1383                        make_service_overridable(v, 0);
1384                        continue;
1385                }
1386                if (!strcmp(arg, "--informative-errors")) {
1387                        informative_errors = 1;
1388                        continue;
1389                }
1390                if (!strcmp(arg, "--no-informative-errors")) {
1391                        informative_errors = 0;
1392                        continue;
1393                }
1394                if (!strcmp(arg, "--")) {
1395                        ok_paths = &argv[i+1];
1396                        break;
1397                } else if (arg[0] != '-') {
1398                        ok_paths = &argv[i];
1399                        break;
1400                }
1401
1402                usage(daemon_usage);
1403        }
1404
1405        if (log_syslog) {
1406                openlog("git-daemon", LOG_PID, LOG_DAEMON);
1407                set_die_routine(daemon_die);
1408        } else
1409                /* avoid splitting a message in the middle */
1410                setvbuf(stderr, NULL, _IOFBF, 4096);
1411
1412        if (inetd_mode && (detach || group_name || user_name))
1413                die("--detach, --user and --group are incompatible with --inetd");
1414
1415        if (inetd_mode && (listen_port || (listen_addr.nr > 0)))
1416                die("--listen= and --port= are incompatible with --inetd");
1417        else if (listen_port == 0)
1418                listen_port = DEFAULT_GIT_PORT;
1419
1420        if (group_name && !user_name)
1421                die("--group supplied without --user");
1422
1423        if (user_name)
1424                cred = prepare_credentials(user_name, group_name);
1425
1426        if (strict_paths && (!ok_paths || !*ok_paths))
1427                die("option --strict-paths requires a whitelist");
1428
1429        if (base_path && !is_directory(base_path))
1430                die("base-path '%s' does not exist or is not a directory",
1431                    base_path);
1432
1433        if (inetd_mode) {
1434                if (!freopen("/dev/null", "w", stderr))
1435                        die_errno("failed to redirect stderr to /dev/null");
1436        }
1437
1438        if (inetd_mode || serve_mode)
1439                return execute();
1440
1441        if (detach) {
1442                if (daemonize())
1443                        die("--detach not supported on this platform");
1444        }
1445
1446        if (pid_file)
1447                write_file(pid_file, "%"PRIuMAX, (uintmax_t) getpid());
1448
1449        /* prepare argv for serving-processes */
1450        argv_array_push(&cld_argv, argv[0]); /* git-daemon */
1451        argv_array_push(&cld_argv, "--serve");
1452        for (i = 1; i < argc; ++i)
1453                argv_array_push(&cld_argv, argv[i]);
1454
1455        return serve(&listen_addr, listen_port, cred);
1456}