Andrew's git / gitweb.git / daemon.c
?
daemon.con commit Merge branch 'jc/report-path-error-to-dir' into maint (ab0fb57)
   1#include "cache.h"
   2#include "pkt-line.h"
   3#include "exec_cmd.h"
   4#include "run-command.h"
   5#include "strbuf.h"
   6#include "string-list.h"
   7
   8#ifndef HOST_NAME_MAX
   9#define HOST_NAME_MAX 256
  10#endif
  11
  12#ifdef NO_INITGROUPS
  13#define initgroups(x, y) (0) /* nothing */
  14#endif
  15
  16static int log_syslog;
  17static int verbose;
  18static int reuseaddr;
  19static int informative_errors;
  20
  21static const char daemon_usage[] =
  22"git daemon [--verbose] [--syslog] [--export-all]\n"
  23"           [--timeout=<n>] [--init-timeout=<n>] [--max-connections=<n>]\n"
  24"           [--strict-paths] [--base-path=<path>] [--base-path-relaxed]\n"
  25"           [--user-path | --user-path=<path>]\n"
  26"           [--interpolated-path=<path>]\n"
  27"           [--reuseaddr] [--pid-file=<file>]\n"
  28"           [--(enable|disable|allow-override|forbid-override)=<service>]\n"
  29"           [--access-hook=<path>]\n"
  30"           [--inetd | [--listen=<host_or_ipaddr>] [--port=<n>]\n"
  31"                      [--detach] [--user=<user> [--group=<group>]]\n"
  32"           [<directory>...]";
  33
  34/* List of acceptable pathname prefixes */
  35static char **ok_paths;
  36static int strict_paths;
  37
  38/* If this is set, git-daemon-export-ok is not required */
  39static int export_all_trees;
  40
  41/* Take all paths relative to this one if non-NULL */
  42static const char *base_path;
  43static const char *interpolated_path;
  44static int base_path_relaxed;
  45
  46/* Flag indicating client sent extra args. */
  47static int saw_extended_args;
  48
  49/* If defined, ~user notation is allowed and the string is inserted
  50 * after ~user/.  E.g. a request to git://host/~alice/frotz would
  51 * go to /home/alice/pub_git/frotz with --user-path=pub_git.
  52 */
  53static const char *user_path;
  54
  55/* Timeout, and initial timeout */
  56static unsigned int timeout;
  57static unsigned int init_timeout;
  58
  59static char *hostname;
  60static char *canon_hostname;
  61static char *ip_address;
  62static char *tcp_port;
  63
  64static int hostname_lookup_done;
  65
  66static void lookup_hostname(void);
  67
  68static const char *get_canon_hostname(void)
  69{
  70        lookup_hostname();
  71        return canon_hostname;
  72}
  73
  74static const char *get_ip_address(void)
  75{
  76        lookup_hostname();
  77        return ip_address;
  78}
  79
  80static void logreport(int priority, const char *err, va_list params)
  81{
  82        if (log_syslog) {
  83                char buf[1024];
  84                vsnprintf(buf, sizeof(buf), err, params);
  85                syslog(priority, "%s", buf);
  86        } else {
  87                /*
  88                 * Since stderr is set to buffered mode, the
  89                 * logging of different processes will not overlap
  90                 * unless they overflow the (rather big) buffers.
  91                 */
  92                fprintf(stderr, "[%"PRIuMAX"] ", (uintmax_t)getpid());
  93                vfprintf(stderr, err, params);
  94                fputc('\n', stderr);
  95                fflush(stderr);
  96        }
  97}
  98
  99__attribute__((format (printf, 1, 2)))
 100static void logerror(const char *err, ...)
 101{
 102        va_list params;
 103        va_start(params, err);
 104        logreport(LOG_ERR, err, params);
 105        va_end(params);
 106}
 107
 108__attribute__((format (printf, 1, 2)))
 109static void loginfo(const char *err, ...)
 110{
 111        va_list params;
 112        if (!verbose)
 113                return;
 114        va_start(params, err);
 115        logreport(LOG_INFO, err, params);
 116        va_end(params);
 117}
 118
 119static void NORETURN daemon_die(const char *err, va_list params)
 120{
 121        logreport(LOG_ERR, err, params);
 122        exit(1);
 123}
 124
 125static void strbuf_addstr_or_null(struct strbuf *sb, const char *s)
 126{
 127        if (s)
 128                strbuf_addstr(sb, s);
 129}
 130
 131struct expand_path_context {
 132        const char *directory;
 133};
 134
 135static size_t expand_path(struct strbuf *sb, const char *placeholder, void *ctx)
 136{
 137        struct expand_path_context *context = ctx;
 138
 139        switch (placeholder[0]) {
 140        case 'H':
 141                strbuf_addstr_or_null(sb, hostname);
 142                return 1;
 143        case 'C':
 144                if (placeholder[1] == 'H') {
 145                        strbuf_addstr_or_null(sb, get_canon_hostname());
 146                        return 2;
 147                }
 148                break;
 149        case 'I':
 150                if (placeholder[1] == 'P') {
 151                        strbuf_addstr_or_null(sb, get_ip_address());
 152                        return 2;
 153                }
 154                break;
 155        case 'P':
 156                strbuf_addstr_or_null(sb, tcp_port);
 157                return 1;
 158        case 'D':
 159                strbuf_addstr(sb, context->directory);
 160                return 1;
 161        }
 162        return 0;
 163}
 164
 165static const char *path_ok(const char *directory)
 166{
 167        static char rpath[PATH_MAX];
 168        static char interp_path[PATH_MAX];
 169        const char *path;
 170        const char *dir;
 171
 172        dir = directory;
 173
 174        if (daemon_avoid_alias(dir)) {
 175                logerror("'%s': aliased", dir);
 176                return NULL;
 177        }
 178
 179        if (*dir == '~') {
 180                if (!user_path) {
 181                        logerror("'%s': User-path not allowed", dir);
 182                        return NULL;
 183                }
 184                if (*user_path) {
 185                        /* Got either "~alice" or "~alice/foo";
 186                         * rewrite them to "~alice/%s" or
 187                         * "~alice/%s/foo".
 188                         */
 189                        int namlen, restlen = strlen(dir);
 190                        const char *slash = strchr(dir, '/');
 191                        if (!slash)
 192                                slash = dir + restlen;
 193                        namlen = slash - dir;
 194                        restlen -= namlen;
 195                        loginfo("userpath <%s>, request <%s>, namlen %d, restlen %d, slash <%s>", user_path, dir, namlen, restlen, slash);
 196                        snprintf(rpath, PATH_MAX, "%.*s/%s%.*s",
 197                                 namlen, dir, user_path, restlen, slash);
 198                        dir = rpath;
 199                }
 200        }
 201        else if (interpolated_path && saw_extended_args) {
 202                struct strbuf expanded_path = STRBUF_INIT;
 203                struct expand_path_context context;
 204
 205                context.directory = directory;
 206
 207                if (*dir != '/') {
 208                        /* Allow only absolute */
 209                        logerror("'%s': Non-absolute path denied (interpolated-path active)", dir);
 210                        return NULL;
 211                }
 212
 213                strbuf_expand(&expanded_path, interpolated_path,
 214                              expand_path, &context);
 215                strlcpy(interp_path, expanded_path.buf, PATH_MAX);
 216                strbuf_release(&expanded_path);
 217                loginfo("Interpolated dir '%s'", interp_path);
 218
 219                dir = interp_path;
 220        }
 221        else if (base_path) {
 222                if (*dir != '/') {
 223                        /* Allow only absolute */
 224                        logerror("'%s': Non-absolute path denied (base-path active)", dir);
 225                        return NULL;
 226                }
 227                snprintf(rpath, PATH_MAX, "%s%s", base_path, dir);
 228                dir = rpath;
 229        }
 230
 231        path = enter_repo(dir, strict_paths);
 232        if (!path && base_path && base_path_relaxed) {
 233                /*
 234                 * if we fail and base_path_relaxed is enabled, try without
 235                 * prefixing the base path
 236                 */
 237                dir = directory;
 238                path = enter_repo(dir, strict_paths);
 239        }
 240
 241        if (!path) {
 242                logerror("'%s' does not appear to be a git repository", dir);
 243                return NULL;
 244        }
 245
 246        if ( ok_paths && *ok_paths ) {
 247                char **pp;
 248                int pathlen = strlen(path);
 249
 250                /* The validation is done on the paths after enter_repo
 251                 * appends optional {.git,.git/.git} and friends, but
 252                 * it does not use getcwd().  So if your /pub is
 253                 * a symlink to /mnt/pub, you can whitelist /pub and
 254                 * do not have to say /mnt/pub.
 255                 * Do not say /pub/.
 256                 */
 257                for ( pp = ok_paths ; *pp ; pp++ ) {
 258                        int len = strlen(*pp);
 259                        if (len <= pathlen &&
 260                            !memcmp(*pp, path, len) &&
 261                            (path[len] == '\0' ||
 262                             (!strict_paths && path[len] == '/')))
 263                                return path;
 264                }
 265        }
 266        else {
 267                /* be backwards compatible */
 268                if (!strict_paths)
 269                        return path;
 270        }
 271
 272        logerror("'%s': not in whitelist", path);
 273        return NULL;            /* Fallthrough. Deny by default */
 274}
 275
 276typedef int (*daemon_service_fn)(void);
 277struct daemon_service {
 278        const char *name;
 279        const char *config_name;
 280        daemon_service_fn fn;
 281        int enabled;
 282        int overridable;
 283};
 284
 285static int daemon_error(const char *dir, const char *msg)
 286{
 287        if (!informative_errors)
 288                msg = "access denied or repository not exported";
 289        packet_write(1, "ERR %s: %s", msg, dir);
 290        return -1;
 291}
 292
 293static const char *access_hook;
 294
 295static int run_access_hook(struct daemon_service *service, const char *dir, const char *path)
 296{
 297        struct child_process child = CHILD_PROCESS_INIT;
 298        struct strbuf buf = STRBUF_INIT;
 299        const char *argv[8];
 300        const char **arg = argv;
 301        char *eol;
 302        int seen_errors = 0;
 303
 304#define STRARG(x) ((x) ? (x) : "")
 305        *arg++ = access_hook;
 306        *arg++ = service->name;
 307        *arg++ = path;
 308        *arg++ = STRARG(hostname);
 309        *arg++ = STRARG(get_canon_hostname());
 310        *arg++ = STRARG(get_ip_address());
 311        *arg++ = STRARG(tcp_port);
 312        *arg = NULL;
 313#undef STRARG
 314
 315        child.use_shell = 1;
 316        child.argv = argv;
 317        child.no_stdin = 1;
 318        child.no_stderr = 1;
 319        child.out = -1;
 320        if (start_command(&child)) {
 321                logerror("daemon access hook '%s' failed to start",
 322                         access_hook);
 323                goto error_return;
 324        }
 325        if (strbuf_read(&buf, child.out, 0) < 0) {
 326                logerror("failed to read from pipe to daemon access hook '%s'",
 327                         access_hook);
 328                strbuf_reset(&buf);
 329                seen_errors = 1;
 330        }
 331        if (close(child.out) < 0) {
 332                logerror("failed to close pipe to daemon access hook '%s'",
 333                         access_hook);
 334                seen_errors = 1;
 335        }
 336        if (finish_command(&child))
 337                seen_errors = 1;
 338
 339        if (!seen_errors) {
 340                strbuf_release(&buf);
 341                return 0;
 342        }
 343
 344error_return:
 345        strbuf_ltrim(&buf);
 346        if (!buf.len)
 347                strbuf_addstr(&buf, "service rejected");
 348        eol = strchr(buf.buf, '\n');
 349        if (eol)
 350                *eol = '\0';
 351        errno = EACCES;
 352        daemon_error(dir, buf.buf);
 353        strbuf_release(&buf);
 354        return -1;
 355}
 356
 357static int run_service(const char *dir, struct daemon_service *service)
 358{
 359        const char *path;
 360        int enabled = service->enabled;
 361        struct strbuf var = STRBUF_INIT;
 362
 363        loginfo("Request %s for '%s'", service->name, dir);
 364
 365        if (!enabled && !service->overridable) {
 366                logerror("'%s': service not enabled.", service->name);
 367                errno = EACCES;
 368                return daemon_error(dir, "service not enabled");
 369        }
 370
 371        if (!(path = path_ok(dir)))
 372                return daemon_error(dir, "no such repository");
 373
 374        /*
 375         * Security on the cheap.
 376         *
 377         * We want a readable HEAD, usable "objects" directory, and
 378         * a "git-daemon-export-ok" flag that says that the other side
 379         * is ok with us doing this.
 380         *
 381         * path_ok() uses enter_repo() and does whitelist checking.
 382         * We only need to make sure the repository is exported.
 383         */
 384
 385        if (!export_all_trees && access("git-daemon-export-ok", F_OK)) {
 386                logerror("'%s': repository not exported.", path);
 387                errno = EACCES;
 388                return daemon_error(dir, "repository not exported");
 389        }
 390
 391        if (service->overridable) {
 392                strbuf_addf(&var, "daemon.%s", service->config_name);
 393                git_config_get_bool(var.buf, &enabled);
 394                strbuf_release(&var);
 395        }
 396        if (!enabled) {
 397                logerror("'%s': service not enabled for '%s'",
 398                         service->name, path);
 399                errno = EACCES;
 400                return daemon_error(dir, "service not enabled");
 401        }
 402
 403        /*
 404         * Optionally, a hook can choose to deny access to the
 405         * repository depending on the phase of the moon.
 406         */
 407        if (access_hook && run_access_hook(service, dir, path))
 408                return -1;
 409
 410        /*
 411         * We'll ignore SIGTERM from now on, we have a
 412         * good client.
 413         */
 414        signal(SIGTERM, SIG_IGN);
 415
 416        return service->fn();
 417}
 418
 419static void copy_to_log(int fd)
 420{
 421        struct strbuf line = STRBUF_INIT;
 422        FILE *fp;
 423
 424        fp = fdopen(fd, "r");
 425        if (fp == NULL) {
 426                logerror("fdopen of error channel failed");
 427                close(fd);
 428                return;
 429        }
 430
 431        while (strbuf_getline(&line, fp, '\n') != EOF) {
 432                logerror("%s", line.buf);
 433                strbuf_setlen(&line, 0);
 434        }
 435
 436        strbuf_release(&line);
 437        fclose(fp);
 438}
 439
 440static int run_service_command(const char **argv)
 441{
 442        struct child_process cld = CHILD_PROCESS_INIT;
 443
 444        cld.argv = argv;
 445        cld.git_cmd = 1;
 446        cld.err = -1;
 447        if (start_command(&cld))
 448                return -1;
 449
 450        close(0);
 451        close(1);
 452
 453        copy_to_log(cld.err);
 454
 455        return finish_command(&cld);
 456}
 457
 458static int upload_pack(void)
 459{
 460        /* Timeout as string */
 461        char timeout_buf[64];
 462        const char *argv[] = { "upload-pack", "--strict", NULL, ".", NULL };
 463
 464        argv[2] = timeout_buf;
 465
 466        snprintf(timeout_buf, sizeof timeout_buf, "--timeout=%u", timeout);
 467        return run_service_command(argv);
 468}
 469
 470static int upload_archive(void)
 471{
 472        static const char *argv[] = { "upload-archive", ".", NULL };
 473        return run_service_command(argv);
 474}
 475
 476static int receive_pack(void)
 477{
 478        static const char *argv[] = { "receive-pack", ".", NULL };
 479        return run_service_command(argv);
 480}
 481
 482static struct daemon_service daemon_service[] = {
 483        { "upload-archive", "uploadarch", upload_archive, 0, 1 },
 484        { "upload-pack", "uploadpack", upload_pack, 1, 1 },
 485        { "receive-pack", "receivepack", receive_pack, 0, 1 },
 486};
 487
 488static void enable_service(const char *name, int ena)
 489{
 490        int i;
 491        for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 492                if (!strcmp(daemon_service[i].name, name)) {
 493                        daemon_service[i].enabled = ena;
 494                        return;
 495                }
 496        }
 497        die("No such service %s", name);
 498}
 499
 500static void make_service_overridable(const char *name, int ena)
 501{
 502        int i;
 503        for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 504                if (!strcmp(daemon_service[i].name, name)) {
 505                        daemon_service[i].overridable = ena;
 506                        return;
 507                }
 508        }
 509        die("No such service %s", name);
 510}
 511
 512static void parse_host_and_port(char *hostport, char **host,
 513        char **port)
 514{
 515        if (*hostport == '[') {
 516                char *end;
 517
 518                end = strchr(hostport, ']');
 519                if (!end)
 520                        die("Invalid request ('[' without ']')");
 521                *end = '\0';
 522                *host = hostport + 1;
 523                if (!end[1])
 524                        *port = NULL;
 525                else if (end[1] == ':')
 526                        *port = end + 2;
 527                else
 528                        die("Garbage after end of host part");
 529        } else {
 530                *host = hostport;
 531                *port = strrchr(hostport, ':');
 532                if (*port) {
 533                        **port = '\0';
 534                        ++*port;
 535                }
 536        }
 537}
 538
 539/*
 540 * Sanitize a string from the client so that it's OK to be inserted into a
 541 * filesystem path. Specifically, we disallow slashes, runs of "..", and
 542 * trailing and leading dots, which means that the client cannot escape
 543 * our base path via ".." traversal.
 544 */
 545static void sanitize_client_strbuf(struct strbuf *out, const char *in)
 546{
 547        for (; *in; in++) {
 548                if (*in == '/')
 549                        continue;
 550                if (*in == '.' && (!out->len || out->buf[out->len - 1] == '.'))
 551                        continue;
 552                strbuf_addch(out, *in);
 553        }
 554
 555        while (out->len && out->buf[out->len - 1] == '.')
 556                strbuf_setlen(out, out->len - 1);
 557}
 558
 559static char *sanitize_client(const char *in)
 560{
 561        struct strbuf out = STRBUF_INIT;
 562        sanitize_client_strbuf(&out, in);
 563        return strbuf_detach(&out, NULL);
 564}
 565
 566/*
 567 * Like sanitize_client, but we also perform any canonicalization
 568 * to make life easier on the admin.
 569 */
 570static char *canonicalize_client(const char *in)
 571{
 572        struct strbuf out = STRBUF_INIT;
 573        sanitize_client_strbuf(&out, in);
 574        strbuf_tolower(&out);
 575        return strbuf_detach(&out, NULL);
 576}
 577
 578/*
 579 * Read the host as supplied by the client connection.
 580 */
 581static void parse_host_arg(char *extra_args, int buflen)
 582{
 583        char *val;
 584        int vallen;
 585        char *end = extra_args + buflen;
 586
 587        if (extra_args < end && *extra_args) {
 588                saw_extended_args = 1;
 589                if (strncasecmp("host=", extra_args, 5) == 0) {
 590                        val = extra_args + 5;
 591                        vallen = strlen(val) + 1;
 592                        if (*val) {
 593                                /* Split <host>:<port> at colon. */
 594                                char *host;
 595                                char *port;
 596                                parse_host_and_port(val, &host, &port);
 597                                if (port) {
 598                                        free(tcp_port);
 599                                        tcp_port = sanitize_client(port);
 600                                }
 601                                free(hostname);
 602                                hostname = canonicalize_client(host);
 603                                hostname_lookup_done = 0;
 604                        }
 605
 606                        /* On to the next one */
 607                        extra_args = val + vallen;
 608                }
 609                if (extra_args < end && *extra_args)
 610                        die("Invalid request");
 611        }
 612}
 613
 614/*
 615 * Locate canonical hostname and its IP address.
 616 */
 617static void lookup_hostname(void)
 618{
 619        if (!hostname_lookup_done && hostname) {
 620#ifndef NO_IPV6
 621                struct addrinfo hints;
 622                struct addrinfo *ai;
 623                int gai;
 624                static char addrbuf[HOST_NAME_MAX + 1];
 625
 626                memset(&hints, 0, sizeof(hints));
 627                hints.ai_flags = AI_CANONNAME;
 628
 629                gai = getaddrinfo(hostname, NULL, &hints, &ai);
 630                if (!gai) {
 631                        struct sockaddr_in *sin_addr = (void *)ai->ai_addr;
 632
 633                        inet_ntop(AF_INET, &sin_addr->sin_addr,
 634                                  addrbuf, sizeof(addrbuf));
 635                        free(ip_address);
 636                        ip_address = xstrdup(addrbuf);
 637
 638                        free(canon_hostname);
 639                        canon_hostname = ai->ai_canonname ?
 640                                sanitize_client(ai->ai_canonname) :
 641                                xstrdup(ip_address);
 642
 643                        freeaddrinfo(ai);
 644                }
 645#else
 646                struct hostent *hent;
 647                struct sockaddr_in sa;
 648                char **ap;
 649                static char addrbuf[HOST_NAME_MAX + 1];
 650
 651                hent = gethostbyname(hostname);
 652                if (hent) {
 653                        ap = hent->h_addr_list;
 654                        memset(&sa, 0, sizeof sa);
 655                        sa.sin_family = hent->h_addrtype;
 656                        sa.sin_port = htons(0);
 657                        memcpy(&sa.sin_addr, *ap, hent->h_length);
 658
 659                        inet_ntop(hent->h_addrtype, &sa.sin_addr,
 660                                  addrbuf, sizeof(addrbuf));
 661
 662                        free(canon_hostname);
 663                        canon_hostname = sanitize_client(hent->h_name);
 664                        free(ip_address);
 665                        ip_address = xstrdup(addrbuf);
 666                }
 667#endif
 668                hostname_lookup_done = 1;
 669        }
 670}
 671
 672
 673static int execute(void)
 674{
 675        char *line = packet_buffer;
 676        int pktlen, len, i;
 677        char *addr = getenv("REMOTE_ADDR"), *port = getenv("REMOTE_PORT");
 678
 679        if (addr)
 680                loginfo("Connection from %s:%s", addr, port);
 681
 682        alarm(init_timeout ? init_timeout : timeout);
 683        pktlen = packet_read(0, NULL, NULL, packet_buffer, sizeof(packet_buffer), 0);
 684        alarm(0);
 685
 686        len = strlen(line);
 687        if (pktlen != len)
 688                loginfo("Extended attributes (%d bytes) exist <%.*s>",
 689                        (int) pktlen - len,
 690                        (int) pktlen - len, line + len + 1);
 691        if (len && line[len-1] == '\n') {
 692                line[--len] = 0;
 693                pktlen--;
 694        }
 695
 696        free(hostname);
 697        free(canon_hostname);
 698        free(ip_address);
 699        free(tcp_port);
 700        hostname = canon_hostname = ip_address = tcp_port = NULL;
 701
 702        if (len != pktlen)
 703                parse_host_arg(line + len + 1, pktlen - len - 1);
 704
 705        for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 706                struct daemon_service *s = &(daemon_service[i]);
 707                const char *arg;
 708
 709                if (skip_prefix(line, "git-", &arg) &&
 710                    skip_prefix(arg, s->name, &arg) &&
 711                    *arg++ == ' ') {
 712                        /*
 713                         * Note: The directory here is probably context sensitive,
 714                         * and might depend on the actual service being performed.
 715                         */
 716                        return run_service(arg, s);
 717                }
 718        }
 719
 720        logerror("Protocol error: '%s'", line);
 721        return -1;
 722}
 723
 724static int addrcmp(const struct sockaddr_storage *s1,
 725    const struct sockaddr_storage *s2)
 726{
 727        const struct sockaddr *sa1 = (const struct sockaddr*) s1;
 728        const struct sockaddr *sa2 = (const struct sockaddr*) s2;
 729
 730        if (sa1->sa_family != sa2->sa_family)
 731                return sa1->sa_family - sa2->sa_family;
 732        if (sa1->sa_family == AF_INET)
 733                return memcmp(&((struct sockaddr_in *)s1)->sin_addr,
 734                    &((struct sockaddr_in *)s2)->sin_addr,
 735                    sizeof(struct in_addr));
 736#ifndef NO_IPV6
 737        if (sa1->sa_family == AF_INET6)
 738                return memcmp(&((struct sockaddr_in6 *)s1)->sin6_addr,
 739                    &((struct sockaddr_in6 *)s2)->sin6_addr,
 740                    sizeof(struct in6_addr));
 741#endif
 742        return 0;
 743}
 744
 745static int max_connections = 32;
 746
 747static unsigned int live_children;
 748
 749static struct child {
 750        struct child *next;
 751        struct child_process cld;
 752        struct sockaddr_storage address;
 753} *firstborn;
 754
 755static void add_child(struct child_process *cld, struct sockaddr *addr, socklen_t addrlen)
 756{
 757        struct child *newborn, **cradle;
 758
 759        newborn = xcalloc(1, sizeof(*newborn));
 760        live_children++;
 761        memcpy(&newborn->cld, cld, sizeof(*cld));
 762        memcpy(&newborn->address, addr, addrlen);
 763        for (cradle = &firstborn; *cradle; cradle = &(*cradle)->next)
 764                if (!addrcmp(&(*cradle)->address, &newborn->address))
 765                        break;
 766        newborn->next = *cradle;
 767        *cradle = newborn;
 768}
 769
 770/*
 771 * This gets called if the number of connections grows
 772 * past "max_connections".
 773 *
 774 * We kill the newest connection from a duplicate IP.
 775 */
 776static void kill_some_child(void)
 777{
 778        const struct child *blanket, *next;
 779
 780        if (!(blanket = firstborn))
 781                return;
 782
 783        for (; (next = blanket->next); blanket = next)
 784                if (!addrcmp(&blanket->address, &next->address)) {
 785                        kill(blanket->cld.pid, SIGTERM);
 786                        break;
 787                }
 788}
 789
 790static void check_dead_children(void)
 791{
 792        int status;
 793        pid_t pid;
 794
 795        struct child **cradle, *blanket;
 796        for (cradle = &firstborn; (blanket = *cradle);)
 797                if ((pid = waitpid(blanket->cld.pid, &status, WNOHANG)) > 1) {
 798                        const char *dead = "";
 799                        if (status)
 800                                dead = " (with error)";
 801                        loginfo("[%"PRIuMAX"] Disconnected%s", (uintmax_t)pid, dead);
 802
 803                        /* remove the child */
 804                        *cradle = blanket->next;
 805                        live_children--;
 806                        free(blanket);
 807                } else
 808                        cradle = &blanket->next;
 809}
 810
 811static char **cld_argv;
 812static void handle(int incoming, struct sockaddr *addr, socklen_t addrlen)
 813{
 814        struct child_process cld = CHILD_PROCESS_INIT;
 815        char addrbuf[300] = "REMOTE_ADDR=", portbuf[300];
 816        char *env[] = { addrbuf, portbuf, NULL };
 817
 818        if (max_connections && live_children >= max_connections) {
 819                kill_some_child();
 820                sleep(1);  /* give it some time to die */
 821                check_dead_children();
 822                if (live_children >= max_connections) {
 823                        close(incoming);
 824                        logerror("Too many children, dropping connection");
 825                        return;
 826                }
 827        }
 828
 829        if (addr->sa_family == AF_INET) {
 830                struct sockaddr_in *sin_addr = (void *) addr;
 831                inet_ntop(addr->sa_family, &sin_addr->sin_addr, addrbuf + 12,
 832                    sizeof(addrbuf) - 12);
 833                snprintf(portbuf, sizeof(portbuf), "REMOTE_PORT=%d",
 834                    ntohs(sin_addr->sin_port));
 835#ifndef NO_IPV6
 836        } else if (addr->sa_family == AF_INET6) {
 837                struct sockaddr_in6 *sin6_addr = (void *) addr;
 838
 839                char *buf = addrbuf + 12;
 840                *buf++ = '['; *buf = '\0'; /* stpcpy() is cool */
 841                inet_ntop(AF_INET6, &sin6_addr->sin6_addr, buf,
 842                    sizeof(addrbuf) - 13);
 843                strcat(buf, "]");
 844
 845                snprintf(portbuf, sizeof(portbuf), "REMOTE_PORT=%d",
 846                    ntohs(sin6_addr->sin6_port));
 847#endif
 848        }
 849
 850        cld.env = (const char **)env;
 851        cld.argv = (const char **)cld_argv;
 852        cld.in = incoming;
 853        cld.out = dup(incoming);
 854
 855        if (start_command(&cld))
 856                logerror("unable to fork");
 857        else
 858                add_child(&cld, addr, addrlen);
 859}
 860
 861static void child_handler(int signo)
 862{
 863        /*
 864         * Otherwise empty handler because systemcalls will get interrupted
 865         * upon signal receipt
 866         * SysV needs the handler to be rearmed
 867         */
 868        signal(SIGCHLD, child_handler);
 869}
 870
 871static int set_reuse_addr(int sockfd)
 872{
 873        int on = 1;
 874
 875        if (!reuseaddr)
 876                return 0;
 877        return setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
 878                          &on, sizeof(on));
 879}
 880
 881struct socketlist {
 882        int *list;
 883        size_t nr;
 884        size_t alloc;
 885};
 886
 887static const char *ip2str(int family, struct sockaddr *sin, socklen_t len)
 888{
 889#ifdef NO_IPV6
 890        static char ip[INET_ADDRSTRLEN];
 891#else
 892        static char ip[INET6_ADDRSTRLEN];
 893#endif
 894
 895        switch (family) {
 896#ifndef NO_IPV6
 897        case AF_INET6:
 898                inet_ntop(family, &((struct sockaddr_in6*)sin)->sin6_addr, ip, len);
 899                break;
 900#endif
 901        case AF_INET:
 902                inet_ntop(family, &((struct sockaddr_in*)sin)->sin_addr, ip, len);
 903                break;
 904        default:
 905                strcpy(ip, "<unknown>");
 906        }
 907        return ip;
 908}
 909
 910#ifndef NO_IPV6
 911
 912static int setup_named_sock(char *listen_addr, int listen_port, struct socketlist *socklist)
 913{
 914        int socknum = 0;
 915        char pbuf[NI_MAXSERV];
 916        struct addrinfo hints, *ai0, *ai;
 917        int gai;
 918        long flags;
 919
 920        sprintf(pbuf, "%d", listen_port);
 921        memset(&hints, 0, sizeof(hints));
 922        hints.ai_family = AF_UNSPEC;
 923        hints.ai_socktype = SOCK_STREAM;
 924        hints.ai_protocol = IPPROTO_TCP;
 925        hints.ai_flags = AI_PASSIVE;
 926
 927        gai = getaddrinfo(listen_addr, pbuf, &hints, &ai0);
 928        if (gai) {
 929                logerror("getaddrinfo() for %s failed: %s", listen_addr, gai_strerror(gai));
 930                return 0;
 931        }
 932
 933        for (ai = ai0; ai; ai = ai->ai_next) {
 934                int sockfd;
 935
 936                sockfd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
 937                if (sockfd < 0)
 938                        continue;
 939                if (sockfd >= FD_SETSIZE) {
 940                        logerror("Socket descriptor too large");
 941                        close(sockfd);
 942                        continue;
 943                }
 944
 945#ifdef IPV6_V6ONLY
 946                if (ai->ai_family == AF_INET6) {
 947                        int on = 1;
 948                        setsockopt(sockfd, IPPROTO_IPV6, IPV6_V6ONLY,
 949                                   &on, sizeof(on));
 950                        /* Note: error is not fatal */
 951                }
 952#endif
 953
 954                if (set_reuse_addr(sockfd)) {
 955                        logerror("Could not set SO_REUSEADDR: %s", strerror(errno));
 956                        close(sockfd);
 957                        continue;
 958                }
 959
 960                if (bind(sockfd, ai->ai_addr, ai->ai_addrlen) < 0) {
 961                        logerror("Could not bind to %s: %s",
 962                                 ip2str(ai->ai_family, ai->ai_addr, ai->ai_addrlen),
 963                                 strerror(errno));
 964                        close(sockfd);
 965                        continue;       /* not fatal */
 966                }
 967                if (listen(sockfd, 5) < 0) {
 968                        logerror("Could not listen to %s: %s",
 969                                 ip2str(ai->ai_family, ai->ai_addr, ai->ai_addrlen),
 970                                 strerror(errno));
 971                        close(sockfd);
 972                        continue;       /* not fatal */
 973                }
 974
 975                flags = fcntl(sockfd, F_GETFD, 0);
 976                if (flags >= 0)
 977                        fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
 978
 979                ALLOC_GROW(socklist->list, socklist->nr + 1, socklist->alloc);
 980                socklist->list[socklist->nr++] = sockfd;
 981                socknum++;
 982        }
 983
 984        freeaddrinfo(ai0);
 985
 986        return socknum;
 987}
 988
 989#else /* NO_IPV6 */
 990
 991static int setup_named_sock(char *listen_addr, int listen_port, struct socketlist *socklist)
 992{
 993        struct sockaddr_in sin;
 994        int sockfd;
 995        long flags;
 996
 997        memset(&sin, 0, sizeof sin);
 998        sin.sin_family = AF_INET;
 999        sin.sin_port = htons(listen_port);
1000
1001        if (listen_addr) {
1002                /* Well, host better be an IP address here. */
1003                if (inet_pton(AF_INET, listen_addr, &sin.sin_addr.s_addr) <= 0)
1004                        return 0;
1005        } else {
1006                sin.sin_addr.s_addr = htonl(INADDR_ANY);
1007        }
1008
1009        sockfd = socket(AF_INET, SOCK_STREAM, 0);
1010        if (sockfd < 0)
1011                return 0;
1012
1013        if (set_reuse_addr(sockfd)) {
1014                logerror("Could not set SO_REUSEADDR: %s", strerror(errno));
1015                close(sockfd);
1016                return 0;
1017        }
1018
1019        if ( bind(sockfd, (struct sockaddr *)&sin, sizeof sin) < 0 ) {
1020                logerror("Could not bind to %s: %s",
1021                         ip2str(AF_INET, (struct sockaddr *)&sin, sizeof(sin)),
1022                         strerror(errno));
1023                close(sockfd);
1024                return 0;
1025        }
1026
1027        if (listen(sockfd, 5) < 0) {
1028                logerror("Could not listen to %s: %s",
1029                         ip2str(AF_INET, (struct sockaddr *)&sin, sizeof(sin)),
1030                         strerror(errno));
1031                close(sockfd);
1032                return 0;
1033        }
1034
1035        flags = fcntl(sockfd, F_GETFD, 0);
1036        if (flags >= 0)
1037                fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
1038
1039        ALLOC_GROW(socklist->list, socklist->nr + 1, socklist->alloc);
1040        socklist->list[socklist->nr++] = sockfd;
1041        return 1;
1042}
1043
1044#endif
1045
1046static void socksetup(struct string_list *listen_addr, int listen_port, struct socketlist *socklist)
1047{
1048        if (!listen_addr->nr)
1049                setup_named_sock(NULL, listen_port, socklist);
1050        else {
1051                int i, socknum;
1052                for (i = 0; i < listen_addr->nr; i++) {
1053                        socknum = setup_named_sock(listen_addr->items[i].string,
1054                                                   listen_port, socklist);
1055
1056                        if (socknum == 0)
1057                                logerror("unable to allocate any listen sockets for host %s on port %u",
1058                                         listen_addr->items[i].string, listen_port);
1059                }
1060        }
1061}
1062
1063static int service_loop(struct socketlist *socklist)
1064{
1065        struct pollfd *pfd;
1066        int i;
1067
1068        pfd = xcalloc(socklist->nr, sizeof(struct pollfd));
1069
1070        for (i = 0; i < socklist->nr; i++) {
1071                pfd[i].fd = socklist->list[i];
1072                pfd[i].events = POLLIN;
1073        }
1074
1075        signal(SIGCHLD, child_handler);
1076
1077        for (;;) {
1078                int i;
1079
1080                check_dead_children();
1081
1082                if (poll(pfd, socklist->nr, -1) < 0) {
1083                        if (errno != EINTR) {
1084                                logerror("Poll failed, resuming: %s",
1085                                      strerror(errno));
1086                                sleep(1);
1087                        }
1088                        continue;
1089                }
1090
1091                for (i = 0; i < socklist->nr; i++) {
1092                        if (pfd[i].revents & POLLIN) {
1093                                union {
1094                                        struct sockaddr sa;
1095                                        struct sockaddr_in sai;
1096#ifndef NO_IPV6
1097                                        struct sockaddr_in6 sai6;
1098#endif
1099                                } ss;
1100                                socklen_t sslen = sizeof(ss);
1101                                int incoming = accept(pfd[i].fd, &ss.sa, &sslen);
1102                                if (incoming < 0) {
1103                                        switch (errno) {
1104                                        case EAGAIN:
1105                                        case EINTR:
1106                                        case ECONNABORTED:
1107                                                continue;
1108                                        default:
1109                                                die_errno("accept returned");
1110                                        }
1111                                }
1112                                handle(incoming, &ss.sa, sslen);
1113                        }
1114                }
1115        }
1116}
1117
1118#ifdef NO_POSIX_GOODIES
1119
1120struct credentials;
1121
1122static void drop_privileges(struct credentials *cred)
1123{
1124        /* nothing */
1125}
1126
1127static struct credentials *prepare_credentials(const char *user_name,
1128    const char *group_name)
1129{
1130        die("--user not supported on this platform");
1131}
1132
1133#else
1134
1135struct credentials {
1136        struct passwd *pass;
1137        gid_t gid;
1138};
1139
1140static void drop_privileges(struct credentials *cred)
1141{
1142        if (cred && (initgroups(cred->pass->pw_name, cred->gid) ||
1143            setgid (cred->gid) || setuid(cred->pass->pw_uid)))
1144                die("cannot drop privileges");
1145}
1146
1147static struct credentials *prepare_credentials(const char *user_name,
1148    const char *group_name)
1149{
1150        static struct credentials c;
1151
1152        c.pass = getpwnam(user_name);
1153        if (!c.pass)
1154                die("user not found - %s", user_name);
1155
1156        if (!group_name)
1157                c.gid = c.pass->pw_gid;
1158        else {
1159                struct group *group = getgrnam(group_name);
1160                if (!group)
1161                        die("group not found - %s", group_name);
1162
1163                c.gid = group->gr_gid;
1164        }
1165
1166        return &c;
1167}
1168#endif
1169
1170static void store_pid(const char *path)
1171{
1172        FILE *f = fopen(path, "w");
1173        if (!f)
1174                die_errno("cannot open pid file '%s'", path);
1175        if (fprintf(f, "%"PRIuMAX"\n", (uintmax_t) getpid()) < 0 || fclose(f) != 0)
1176                die_errno("failed to write pid file '%s'", path);
1177}
1178
1179static int serve(struct string_list *listen_addr, int listen_port,
1180    struct credentials *cred)
1181{
1182        struct socketlist socklist = { NULL, 0, 0 };
1183
1184        socksetup(listen_addr, listen_port, &socklist);
1185        if (socklist.nr == 0)
1186                die("unable to allocate any listen sockets on port %u",
1187                    listen_port);
1188
1189        drop_privileges(cred);
1190
1191        loginfo("Ready to rumble");
1192
1193        return service_loop(&socklist);
1194}
1195
1196int main(int argc, char **argv)
1197{
1198        int listen_port = 0;
1199        struct string_list listen_addr = STRING_LIST_INIT_NODUP;
1200        int serve_mode = 0, inetd_mode = 0;
1201        const char *pid_file = NULL, *user_name = NULL, *group_name = NULL;
1202        int detach = 0;
1203        struct credentials *cred = NULL;
1204        int i;
1205
1206        git_setup_gettext();
1207
1208        git_extract_argv0_path(argv[0]);
1209
1210        for (i = 1; i < argc; i++) {
1211                char *arg = argv[i];
1212                const char *v;
1213
1214                if (skip_prefix(arg, "--listen=", &v)) {
1215                        string_list_append(&listen_addr, xstrdup_tolower(v));
1216                        continue;
1217                }
1218                if (skip_prefix(arg, "--port=", &v)) {
1219                        char *end;
1220                        unsigned long n;
1221                        n = strtoul(v, &end, 0);
1222                        if (*v && !*end) {
1223                                listen_port = n;
1224                                continue;
1225                        }
1226                }
1227                if (!strcmp(arg, "--serve")) {
1228                        serve_mode = 1;
1229                        continue;
1230                }
1231                if (!strcmp(arg, "--inetd")) {
1232                        inetd_mode = 1;
1233                        log_syslog = 1;
1234                        continue;
1235                }
1236                if (!strcmp(arg, "--verbose")) {
1237                        verbose = 1;
1238                        continue;
1239                }
1240                if (!strcmp(arg, "--syslog")) {
1241                        log_syslog = 1;
1242                        continue;
1243                }
1244                if (!strcmp(arg, "--export-all")) {
1245                        export_all_trees = 1;
1246                        continue;
1247                }
1248                if (skip_prefix(arg, "--access-hook=", &v)) {
1249                        access_hook = v;
1250                        continue;
1251                }
1252                if (skip_prefix(arg, "--timeout=", &v)) {
1253                        timeout = atoi(v);
1254                        continue;
1255                }
1256                if (skip_prefix(arg, "--init-timeout=", &v)) {
1257                        init_timeout = atoi(v);
1258                        continue;
1259                }
1260                if (skip_prefix(arg, "--max-connections=", &v)) {
1261                        max_connections = atoi(v);
1262                        if (max_connections < 0)
1263                                max_connections = 0;            /* unlimited */
1264                        continue;
1265                }
1266                if (!strcmp(arg, "--strict-paths")) {
1267                        strict_paths = 1;
1268                        continue;
1269                }
1270                if (skip_prefix(arg, "--base-path=", &v)) {
1271                        base_path = v;
1272                        continue;
1273                }
1274                if (!strcmp(arg, "--base-path-relaxed")) {
1275                        base_path_relaxed = 1;
1276                        continue;
1277                }
1278                if (skip_prefix(arg, "--interpolated-path=", &v)) {
1279                        interpolated_path = v;
1280                        continue;
1281                }
1282                if (!strcmp(arg, "--reuseaddr")) {
1283                        reuseaddr = 1;
1284                        continue;
1285                }
1286                if (!strcmp(arg, "--user-path")) {
1287                        user_path = "";
1288                        continue;
1289                }
1290                if (skip_prefix(arg, "--user-path=", &v)) {
1291                        user_path = v;
1292                        continue;
1293                }
1294                if (skip_prefix(arg, "--pid-file=", &v)) {
1295                        pid_file = v;
1296                        continue;
1297                }
1298                if (!strcmp(arg, "--detach")) {
1299                        detach = 1;
1300                        log_syslog = 1;
1301                        continue;
1302                }
1303                if (skip_prefix(arg, "--user=", &v)) {
1304                        user_name = v;
1305                        continue;
1306                }
1307                if (skip_prefix(arg, "--group=", &v)) {
1308                        group_name = v;
1309                        continue;
1310                }
1311                if (skip_prefix(arg, "--enable=", &v)) {
1312                        enable_service(v, 1);
1313                        continue;
1314                }
1315                if (skip_prefix(arg, "--disable=", &v)) {
1316                        enable_service(v, 0);
1317                        continue;
1318                }
1319                if (skip_prefix(arg, "--allow-override=", &v)) {
1320                        make_service_overridable(v, 1);
1321                        continue;
1322                }
1323                if (skip_prefix(arg, "--forbid-override=", &v)) {
1324                        make_service_overridable(v, 0);
1325                        continue;
1326                }
1327                if (!strcmp(arg, "--informative-errors")) {
1328                        informative_errors = 1;
1329                        continue;
1330                }
1331                if (!strcmp(arg, "--no-informative-errors")) {
1332                        informative_errors = 0;
1333                        continue;
1334                }
1335                if (!strcmp(arg, "--")) {
1336                        ok_paths = &argv[i+1];
1337                        break;
1338                } else if (arg[0] != '-') {
1339                        ok_paths = &argv[i];
1340                        break;
1341                }
1342
1343                usage(daemon_usage);
1344        }
1345
1346        if (log_syslog) {
1347                openlog("git-daemon", LOG_PID, LOG_DAEMON);
1348                set_die_routine(daemon_die);
1349        } else
1350                /* avoid splitting a message in the middle */
1351                setvbuf(stderr, NULL, _IOFBF, 4096);
1352
1353        if (inetd_mode && (detach || group_name || user_name))
1354                die("--detach, --user and --group are incompatible with --inetd");
1355
1356        if (inetd_mode && (listen_port || (listen_addr.nr > 0)))
1357                die("--listen= and --port= are incompatible with --inetd");
1358        else if (listen_port == 0)
1359                listen_port = DEFAULT_GIT_PORT;
1360
1361        if (group_name && !user_name)
1362                die("--group supplied without --user");
1363
1364        if (user_name)
1365                cred = prepare_credentials(user_name, group_name);
1366
1367        if (strict_paths && (!ok_paths || !*ok_paths))
1368                die("option --strict-paths requires a whitelist");
1369
1370        if (base_path && !is_directory(base_path))
1371                die("base-path '%s' does not exist or is not a directory",
1372                    base_path);
1373
1374        if (inetd_mode) {
1375                if (!freopen("/dev/null", "w", stderr))
1376                        die_errno("failed to redirect stderr to /dev/null");
1377        }
1378
1379        if (inetd_mode || serve_mode)
1380                return execute();
1381
1382        if (detach) {
1383                if (daemonize())
1384                        die("--detach not supported on this platform");
1385        } else
1386                sanitize_stdfds();
1387
1388        if (pid_file)
1389                store_pid(pid_file);
1390
1391        /* prepare argv for serving-processes */
1392        cld_argv = xmalloc(sizeof (char *) * (argc + 2));
1393        cld_argv[0] = argv[0];  /* git-daemon */
1394        cld_argv[1] = "--serve";
1395        for (i = 1; i < argc; ++i)
1396                cld_argv[i+1] = argv[i];
1397        cld_argv[argc+1] = NULL;
1398
1399        return serve(&listen_addr, listen_port, cred);
1400}