Andrew's git / gitweb.git / daemon.c
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daemon.con commit git_open(): untangle possible NOATIME and CLOEXEC interactions (1b8ac5e)
   1#include "cache.h"
   2#include "pkt-line.h"
   3#include "run-command.h"
   4#include "strbuf.h"
   5#include "string-list.h"
   6
   7#ifndef HOST_NAME_MAX
   8#define HOST_NAME_MAX 256
   9#endif
  10
  11#ifdef NO_INITGROUPS
  12#define initgroups(x, y) (0) /* nothing */
  13#endif
  14
  15static int log_syslog;
  16static int verbose;
  17static int reuseaddr;
  18static int informative_errors;
  19
  20static const char daemon_usage[] =
  21"git daemon [--verbose] [--syslog] [--export-all]\n"
  22"           [--timeout=<n>] [--init-timeout=<n>] [--max-connections=<n>]\n"
  23"           [--strict-paths] [--base-path=<path>] [--base-path-relaxed]\n"
  24"           [--user-path | --user-path=<path>]\n"
  25"           [--interpolated-path=<path>]\n"
  26"           [--reuseaddr] [--pid-file=<file>]\n"
  27"           [--(enable|disable|allow-override|forbid-override)=<service>]\n"
  28"           [--access-hook=<path>]\n"
  29"           [--inetd | [--listen=<host_or_ipaddr>] [--port=<n>]\n"
  30"                      [--detach] [--user=<user> [--group=<group>]]\n"
  31"           [<directory>...]";
  32
  33/* List of acceptable pathname prefixes */
  34static const char **ok_paths;
  35static int strict_paths;
  36
  37/* If this is set, git-daemon-export-ok is not required */
  38static int export_all_trees;
  39
  40/* Take all paths relative to this one if non-NULL */
  41static const char *base_path;
  42static const char *interpolated_path;
  43static int base_path_relaxed;
  44
  45/* If defined, ~user notation is allowed and the string is inserted
  46 * after ~user/.  E.g. a request to git://host/~alice/frotz would
  47 * go to /home/alice/pub_git/frotz with --user-path=pub_git.
  48 */
  49static const char *user_path;
  50
  51/* Timeout, and initial timeout */
  52static unsigned int timeout;
  53static unsigned int init_timeout;
  54
  55struct hostinfo {
  56        struct strbuf hostname;
  57        struct strbuf canon_hostname;
  58        struct strbuf ip_address;
  59        struct strbuf tcp_port;
  60        unsigned int hostname_lookup_done:1;
  61        unsigned int saw_extended_args:1;
  62};
  63
  64static void lookup_hostname(struct hostinfo *hi);
  65
  66static const char *get_canon_hostname(struct hostinfo *hi)
  67{
  68        lookup_hostname(hi);
  69        return hi->canon_hostname.buf;
  70}
  71
  72static const char *get_ip_address(struct hostinfo *hi)
  73{
  74        lookup_hostname(hi);
  75        return hi->ip_address.buf;
  76}
  77
  78static void logreport(int priority, const char *err, va_list params)
  79{
  80        if (log_syslog) {
  81                char buf[1024];
  82                vsnprintf(buf, sizeof(buf), err, params);
  83                syslog(priority, "%s", buf);
  84        } else {
  85                /*
  86                 * Since stderr is set to buffered mode, the
  87                 * logging of different processes will not overlap
  88                 * unless they overflow the (rather big) buffers.
  89                 */
  90                fprintf(stderr, "[%"PRIuMAX"] ", (uintmax_t)getpid());
  91                vfprintf(stderr, err, params);
  92                fputc('\n', stderr);
  93                fflush(stderr);
  94        }
  95}
  96
  97__attribute__((format (printf, 1, 2)))
  98static void logerror(const char *err, ...)
  99{
 100        va_list params;
 101        va_start(params, err);
 102        logreport(LOG_ERR, err, params);
 103        va_end(params);
 104}
 105
 106__attribute__((format (printf, 1, 2)))
 107static void loginfo(const char *err, ...)
 108{
 109        va_list params;
 110        if (!verbose)
 111                return;
 112        va_start(params, err);
 113        logreport(LOG_INFO, err, params);
 114        va_end(params);
 115}
 116
 117static void NORETURN daemon_die(const char *err, va_list params)
 118{
 119        logreport(LOG_ERR, err, params);
 120        exit(1);
 121}
 122
 123struct expand_path_context {
 124        const char *directory;
 125        struct hostinfo *hostinfo;
 126};
 127
 128static size_t expand_path(struct strbuf *sb, const char *placeholder, void *ctx)
 129{
 130        struct expand_path_context *context = ctx;
 131        struct hostinfo *hi = context->hostinfo;
 132
 133        switch (placeholder[0]) {
 134        case 'H':
 135                strbuf_addbuf(sb, &hi->hostname);
 136                return 1;
 137        case 'C':
 138                if (placeholder[1] == 'H') {
 139                        strbuf_addstr(sb, get_canon_hostname(hi));
 140                        return 2;
 141                }
 142                break;
 143        case 'I':
 144                if (placeholder[1] == 'P') {
 145                        strbuf_addstr(sb, get_ip_address(hi));
 146                        return 2;
 147                }
 148                break;
 149        case 'P':
 150                strbuf_addbuf(sb, &hi->tcp_port);
 151                return 1;
 152        case 'D':
 153                strbuf_addstr(sb, context->directory);
 154                return 1;
 155        }
 156        return 0;
 157}
 158
 159static const char *path_ok(const char *directory, struct hostinfo *hi)
 160{
 161        static char rpath[PATH_MAX];
 162        static char interp_path[PATH_MAX];
 163        const char *path;
 164        const char *dir;
 165
 166        dir = directory;
 167
 168        if (daemon_avoid_alias(dir)) {
 169                logerror("'%s': aliased", dir);
 170                return NULL;
 171        }
 172
 173        if (*dir == '~') {
 174                if (!user_path) {
 175                        logerror("'%s': User-path not allowed", dir);
 176                        return NULL;
 177                }
 178                if (*user_path) {
 179                        /* Got either "~alice" or "~alice/foo";
 180                         * rewrite them to "~alice/%s" or
 181                         * "~alice/%s/foo".
 182                         */
 183                        int namlen, restlen = strlen(dir);
 184                        const char *slash = strchr(dir, '/');
 185                        if (!slash)
 186                                slash = dir + restlen;
 187                        namlen = slash - dir;
 188                        restlen -= namlen;
 189                        loginfo("userpath <%s>, request <%s>, namlen %d, restlen %d, slash <%s>", user_path, dir, namlen, restlen, slash);
 190                        snprintf(rpath, PATH_MAX, "%.*s/%s%.*s",
 191                                 namlen, dir, user_path, restlen, slash);
 192                        dir = rpath;
 193                }
 194        }
 195        else if (interpolated_path && hi->saw_extended_args) {
 196                struct strbuf expanded_path = STRBUF_INIT;
 197                struct expand_path_context context;
 198
 199                context.directory = directory;
 200                context.hostinfo = hi;
 201
 202                if (*dir != '/') {
 203                        /* Allow only absolute */
 204                        logerror("'%s': Non-absolute path denied (interpolated-path active)", dir);
 205                        return NULL;
 206                }
 207
 208                strbuf_expand(&expanded_path, interpolated_path,
 209                              expand_path, &context);
 210                strlcpy(interp_path, expanded_path.buf, PATH_MAX);
 211                strbuf_release(&expanded_path);
 212                loginfo("Interpolated dir '%s'", interp_path);
 213
 214                dir = interp_path;
 215        }
 216        else if (base_path) {
 217                if (*dir != '/') {
 218                        /* Allow only absolute */
 219                        logerror("'%s': Non-absolute path denied (base-path active)", dir);
 220                        return NULL;
 221                }
 222                snprintf(rpath, PATH_MAX, "%s%s", base_path, dir);
 223                dir = rpath;
 224        }
 225
 226        path = enter_repo(dir, strict_paths);
 227        if (!path && base_path && base_path_relaxed) {
 228                /*
 229                 * if we fail and base_path_relaxed is enabled, try without
 230                 * prefixing the base path
 231                 */
 232                dir = directory;
 233                path = enter_repo(dir, strict_paths);
 234        }
 235
 236        if (!path) {
 237                logerror("'%s' does not appear to be a git repository", dir);
 238                return NULL;
 239        }
 240
 241        if ( ok_paths && *ok_paths ) {
 242                const char **pp;
 243                int pathlen = strlen(path);
 244
 245                /* The validation is done on the paths after enter_repo
 246                 * appends optional {.git,.git/.git} and friends, but
 247                 * it does not use getcwd().  So if your /pub is
 248                 * a symlink to /mnt/pub, you can whitelist /pub and
 249                 * do not have to say /mnt/pub.
 250                 * Do not say /pub/.
 251                 */
 252                for ( pp = ok_paths ; *pp ; pp++ ) {
 253                        int len = strlen(*pp);
 254                        if (len <= pathlen &&
 255                            !memcmp(*pp, path, len) &&
 256                            (path[len] == '\0' ||
 257                             (!strict_paths && path[len] == '/')))
 258                                return path;
 259                }
 260        }
 261        else {
 262                /* be backwards compatible */
 263                if (!strict_paths)
 264                        return path;
 265        }
 266
 267        logerror("'%s': not in whitelist", path);
 268        return NULL;            /* Fallthrough. Deny by default */
 269}
 270
 271typedef int (*daemon_service_fn)(void);
 272struct daemon_service {
 273        const char *name;
 274        const char *config_name;
 275        daemon_service_fn fn;
 276        int enabled;
 277        int overridable;
 278};
 279
 280static int daemon_error(const char *dir, const char *msg)
 281{
 282        if (!informative_errors)
 283                msg = "access denied or repository not exported";
 284        packet_write(1, "ERR %s: %s", msg, dir);
 285        return -1;
 286}
 287
 288static const char *access_hook;
 289
 290static int run_access_hook(struct daemon_service *service, const char *dir,
 291                           const char *path, struct hostinfo *hi)
 292{
 293        struct child_process child = CHILD_PROCESS_INIT;
 294        struct strbuf buf = STRBUF_INIT;
 295        const char *argv[8];
 296        const char **arg = argv;
 297        char *eol;
 298        int seen_errors = 0;
 299
 300        *arg++ = access_hook;
 301        *arg++ = service->name;
 302        *arg++ = path;
 303        *arg++ = hi->hostname.buf;
 304        *arg++ = get_canon_hostname(hi);
 305        *arg++ = get_ip_address(hi);
 306        *arg++ = hi->tcp_port.buf;
 307        *arg = NULL;
 308
 309        child.use_shell = 1;
 310        child.argv = argv;
 311        child.no_stdin = 1;
 312        child.no_stderr = 1;
 313        child.out = -1;
 314        if (start_command(&child)) {
 315                logerror("daemon access hook '%s' failed to start",
 316                         access_hook);
 317                goto error_return;
 318        }
 319        if (strbuf_read(&buf, child.out, 0) < 0) {
 320                logerror("failed to read from pipe to daemon access hook '%s'",
 321                         access_hook);
 322                strbuf_reset(&buf);
 323                seen_errors = 1;
 324        }
 325        if (close(child.out) < 0) {
 326                logerror("failed to close pipe to daemon access hook '%s'",
 327                         access_hook);
 328                seen_errors = 1;
 329        }
 330        if (finish_command(&child))
 331                seen_errors = 1;
 332
 333        if (!seen_errors) {
 334                strbuf_release(&buf);
 335                return 0;
 336        }
 337
 338error_return:
 339        strbuf_ltrim(&buf);
 340        if (!buf.len)
 341                strbuf_addstr(&buf, "service rejected");
 342        eol = strchr(buf.buf, '\n');
 343        if (eol)
 344                *eol = '\0';
 345        errno = EACCES;
 346        daemon_error(dir, buf.buf);
 347        strbuf_release(&buf);
 348        return -1;
 349}
 350
 351static int run_service(const char *dir, struct daemon_service *service,
 352                       struct hostinfo *hi)
 353{
 354        const char *path;
 355        int enabled = service->enabled;
 356        struct strbuf var = STRBUF_INIT;
 357
 358        loginfo("Request %s for '%s'", service->name, dir);
 359
 360        if (!enabled && !service->overridable) {
 361                logerror("'%s': service not enabled.", service->name);
 362                errno = EACCES;
 363                return daemon_error(dir, "service not enabled");
 364        }
 365
 366        if (!(path = path_ok(dir, hi)))
 367                return daemon_error(dir, "no such repository");
 368
 369        /*
 370         * Security on the cheap.
 371         *
 372         * We want a readable HEAD, usable "objects" directory, and
 373         * a "git-daemon-export-ok" flag that says that the other side
 374         * is ok with us doing this.
 375         *
 376         * path_ok() uses enter_repo() and does whitelist checking.
 377         * We only need to make sure the repository is exported.
 378         */
 379
 380        if (!export_all_trees && access("git-daemon-export-ok", F_OK)) {
 381                logerror("'%s': repository not exported.", path);
 382                errno = EACCES;
 383                return daemon_error(dir, "repository not exported");
 384        }
 385
 386        if (service->overridable) {
 387                strbuf_addf(&var, "daemon.%s", service->config_name);
 388                git_config_get_bool(var.buf, &enabled);
 389                strbuf_release(&var);
 390        }
 391        if (!enabled) {
 392                logerror("'%s': service not enabled for '%s'",
 393                         service->name, path);
 394                errno = EACCES;
 395                return daemon_error(dir, "service not enabled");
 396        }
 397
 398        /*
 399         * Optionally, a hook can choose to deny access to the
 400         * repository depending on the phase of the moon.
 401         */
 402        if (access_hook && run_access_hook(service, dir, path, hi))
 403                return -1;
 404
 405        /*
 406         * We'll ignore SIGTERM from now on, we have a
 407         * good client.
 408         */
 409        signal(SIGTERM, SIG_IGN);
 410
 411        return service->fn();
 412}
 413
 414static void copy_to_log(int fd)
 415{
 416        struct strbuf line = STRBUF_INIT;
 417        FILE *fp;
 418
 419        fp = fdopen(fd, "r");
 420        if (fp == NULL) {
 421                logerror("fdopen of error channel failed");
 422                close(fd);
 423                return;
 424        }
 425
 426        while (strbuf_getline_lf(&line, fp) != EOF) {
 427                logerror("%s", line.buf);
 428                strbuf_setlen(&line, 0);
 429        }
 430
 431        strbuf_release(&line);
 432        fclose(fp);
 433}
 434
 435static int run_service_command(const char **argv)
 436{
 437        struct child_process cld = CHILD_PROCESS_INIT;
 438
 439        cld.argv = argv;
 440        cld.git_cmd = 1;
 441        cld.err = -1;
 442        if (start_command(&cld))
 443                return -1;
 444
 445        close(0);
 446        close(1);
 447
 448        copy_to_log(cld.err);
 449
 450        return finish_command(&cld);
 451}
 452
 453static int upload_pack(void)
 454{
 455        /* Timeout as string */
 456        char timeout_buf[64];
 457        const char *argv[] = { "upload-pack", "--strict", NULL, ".", NULL };
 458
 459        argv[2] = timeout_buf;
 460
 461        snprintf(timeout_buf, sizeof timeout_buf, "--timeout=%u", timeout);
 462        return run_service_command(argv);
 463}
 464
 465static int upload_archive(void)
 466{
 467        static const char *argv[] = { "upload-archive", ".", NULL };
 468        return run_service_command(argv);
 469}
 470
 471static int receive_pack(void)
 472{
 473        static const char *argv[] = { "receive-pack", ".", NULL };
 474        return run_service_command(argv);
 475}
 476
 477static struct daemon_service daemon_service[] = {
 478        { "upload-archive", "uploadarch", upload_archive, 0, 1 },
 479        { "upload-pack", "uploadpack", upload_pack, 1, 1 },
 480        { "receive-pack", "receivepack", receive_pack, 0, 1 },
 481};
 482
 483static void enable_service(const char *name, int ena)
 484{
 485        int i;
 486        for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 487                if (!strcmp(daemon_service[i].name, name)) {
 488                        daemon_service[i].enabled = ena;
 489                        return;
 490                }
 491        }
 492        die("No such service %s", name);
 493}
 494
 495static void make_service_overridable(const char *name, int ena)
 496{
 497        int i;
 498        for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 499                if (!strcmp(daemon_service[i].name, name)) {
 500                        daemon_service[i].overridable = ena;
 501                        return;
 502                }
 503        }
 504        die("No such service %s", name);
 505}
 506
 507static void parse_host_and_port(char *hostport, char **host,
 508        char **port)
 509{
 510        if (*hostport == '[') {
 511                char *end;
 512
 513                end = strchr(hostport, ']');
 514                if (!end)
 515                        die("Invalid request ('[' without ']')");
 516                *end = '\0';
 517                *host = hostport + 1;
 518                if (!end[1])
 519                        *port = NULL;
 520                else if (end[1] == ':')
 521                        *port = end + 2;
 522                else
 523                        die("Garbage after end of host part");
 524        } else {
 525                *host = hostport;
 526                *port = strrchr(hostport, ':');
 527                if (*port) {
 528                        **port = '\0';
 529                        ++*port;
 530                }
 531        }
 532}
 533
 534/*
 535 * Sanitize a string from the client so that it's OK to be inserted into a
 536 * filesystem path. Specifically, we disallow slashes, runs of "..", and
 537 * trailing and leading dots, which means that the client cannot escape
 538 * our base path via ".." traversal.
 539 */
 540static void sanitize_client(struct strbuf *out, const char *in)
 541{
 542        for (; *in; in++) {
 543                if (*in == '/')
 544                        continue;
 545                if (*in == '.' && (!out->len || out->buf[out->len - 1] == '.'))
 546                        continue;
 547                strbuf_addch(out, *in);
 548        }
 549
 550        while (out->len && out->buf[out->len - 1] == '.')
 551                strbuf_setlen(out, out->len - 1);
 552}
 553
 554/*
 555 * Like sanitize_client, but we also perform any canonicalization
 556 * to make life easier on the admin.
 557 */
 558static void canonicalize_client(struct strbuf *out, const char *in)
 559{
 560        sanitize_client(out, in);
 561        strbuf_tolower(out);
 562}
 563
 564/*
 565 * Read the host as supplied by the client connection.
 566 */
 567static void parse_host_arg(struct hostinfo *hi, char *extra_args, int buflen)
 568{
 569        char *val;
 570        int vallen;
 571        char *end = extra_args + buflen;
 572
 573        if (extra_args < end && *extra_args) {
 574                hi->saw_extended_args = 1;
 575                if (strncasecmp("host=", extra_args, 5) == 0) {
 576                        val = extra_args + 5;
 577                        vallen = strlen(val) + 1;
 578                        if (*val) {
 579                                /* Split <host>:<port> at colon. */
 580                                char *host;
 581                                char *port;
 582                                parse_host_and_port(val, &host, &port);
 583                                if (port)
 584                                        sanitize_client(&hi->tcp_port, port);
 585                                canonicalize_client(&hi->hostname, host);
 586                                hi->hostname_lookup_done = 0;
 587                        }
 588
 589                        /* On to the next one */
 590                        extra_args = val + vallen;
 591                }
 592                if (extra_args < end && *extra_args)
 593                        die("Invalid request");
 594        }
 595}
 596
 597/*
 598 * Locate canonical hostname and its IP address.
 599 */
 600static void lookup_hostname(struct hostinfo *hi)
 601{
 602        if (!hi->hostname_lookup_done && hi->hostname.len) {
 603#ifndef NO_IPV6
 604                struct addrinfo hints;
 605                struct addrinfo *ai;
 606                int gai;
 607                static char addrbuf[HOST_NAME_MAX + 1];
 608
 609                memset(&hints, 0, sizeof(hints));
 610                hints.ai_flags = AI_CANONNAME;
 611
 612                gai = getaddrinfo(hi->hostname.buf, NULL, &hints, &ai);
 613                if (!gai) {
 614                        struct sockaddr_in *sin_addr = (void *)ai->ai_addr;
 615
 616                        inet_ntop(AF_INET, &sin_addr->sin_addr,
 617                                  addrbuf, sizeof(addrbuf));
 618                        strbuf_addstr(&hi->ip_address, addrbuf);
 619
 620                        if (ai->ai_canonname)
 621                                sanitize_client(&hi->canon_hostname,
 622                                                ai->ai_canonname);
 623                        else
 624                                strbuf_addbuf(&hi->canon_hostname,
 625                                              &hi->ip_address);
 626
 627                        freeaddrinfo(ai);
 628                }
 629#else
 630                struct hostent *hent;
 631                struct sockaddr_in sa;
 632                char **ap;
 633                static char addrbuf[HOST_NAME_MAX + 1];
 634
 635                hent = gethostbyname(hi->hostname.buf);
 636                if (hent) {
 637                        ap = hent->h_addr_list;
 638                        memset(&sa, 0, sizeof sa);
 639                        sa.sin_family = hent->h_addrtype;
 640                        sa.sin_port = htons(0);
 641                        memcpy(&sa.sin_addr, *ap, hent->h_length);
 642
 643                        inet_ntop(hent->h_addrtype, &sa.sin_addr,
 644                                  addrbuf, sizeof(addrbuf));
 645
 646                        sanitize_client(&hi->canon_hostname, hent->h_name);
 647                        strbuf_addstr(&hi->ip_address, addrbuf);
 648                }
 649#endif
 650                hi->hostname_lookup_done = 1;
 651        }
 652}
 653
 654static void hostinfo_init(struct hostinfo *hi)
 655{
 656        memset(hi, 0, sizeof(*hi));
 657        strbuf_init(&hi->hostname, 0);
 658        strbuf_init(&hi->canon_hostname, 0);
 659        strbuf_init(&hi->ip_address, 0);
 660        strbuf_init(&hi->tcp_port, 0);
 661}
 662
 663static void hostinfo_clear(struct hostinfo *hi)
 664{
 665        strbuf_release(&hi->hostname);
 666        strbuf_release(&hi->canon_hostname);
 667        strbuf_release(&hi->ip_address);
 668        strbuf_release(&hi->tcp_port);
 669}
 670
 671static void set_keep_alive(int sockfd)
 672{
 673        int ka = 1;
 674
 675        if (setsockopt(sockfd, SOL_SOCKET, SO_KEEPALIVE, &ka, sizeof(ka)) < 0) {
 676                if (errno != ENOTSOCK)
 677                        logerror("unable to set SO_KEEPALIVE on socket: %s",
 678                                strerror(errno));
 679        }
 680}
 681
 682static int execute(void)
 683{
 684        char *line = packet_buffer;
 685        int pktlen, len, i;
 686        char *addr = getenv("REMOTE_ADDR"), *port = getenv("REMOTE_PORT");
 687        struct hostinfo hi;
 688
 689        hostinfo_init(&hi);
 690
 691        if (addr)
 692                loginfo("Connection from %s:%s", addr, port);
 693
 694        set_keep_alive(0);
 695        alarm(init_timeout ? init_timeout : timeout);
 696        pktlen = packet_read(0, NULL, NULL, packet_buffer, sizeof(packet_buffer), 0);
 697        alarm(0);
 698
 699        len = strlen(line);
 700        if (pktlen != len)
 701                loginfo("Extended attributes (%d bytes) exist <%.*s>",
 702                        (int) pktlen - len,
 703                        (int) pktlen - len, line + len + 1);
 704        if (len && line[len-1] == '\n') {
 705                line[--len] = 0;
 706                pktlen--;
 707        }
 708
 709        if (len != pktlen)
 710                parse_host_arg(&hi, line + len + 1, pktlen - len - 1);
 711
 712        for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 713                struct daemon_service *s = &(daemon_service[i]);
 714                const char *arg;
 715
 716                if (skip_prefix(line, "git-", &arg) &&
 717                    skip_prefix(arg, s->name, &arg) &&
 718                    *arg++ == ' ') {
 719                        /*
 720                         * Note: The directory here is probably context sensitive,
 721                         * and might depend on the actual service being performed.
 722                         */
 723                        int rc = run_service(arg, s, &hi);
 724                        hostinfo_clear(&hi);
 725                        return rc;
 726                }
 727        }
 728
 729        hostinfo_clear(&hi);
 730        logerror("Protocol error: '%s'", line);
 731        return -1;
 732}
 733
 734static int addrcmp(const struct sockaddr_storage *s1,
 735    const struct sockaddr_storage *s2)
 736{
 737        const struct sockaddr *sa1 = (const struct sockaddr*) s1;
 738        const struct sockaddr *sa2 = (const struct sockaddr*) s2;
 739
 740        if (sa1->sa_family != sa2->sa_family)
 741                return sa1->sa_family - sa2->sa_family;
 742        if (sa1->sa_family == AF_INET)
 743                return memcmp(&((struct sockaddr_in *)s1)->sin_addr,
 744                    &((struct sockaddr_in *)s2)->sin_addr,
 745                    sizeof(struct in_addr));
 746#ifndef NO_IPV6
 747        if (sa1->sa_family == AF_INET6)
 748                return memcmp(&((struct sockaddr_in6 *)s1)->sin6_addr,
 749                    &((struct sockaddr_in6 *)s2)->sin6_addr,
 750                    sizeof(struct in6_addr));
 751#endif
 752        return 0;
 753}
 754
 755static int max_connections = 32;
 756
 757static unsigned int live_children;
 758
 759static struct child {
 760        struct child *next;
 761        struct child_process cld;
 762        struct sockaddr_storage address;
 763} *firstborn;
 764
 765static void add_child(struct child_process *cld, struct sockaddr *addr, socklen_t addrlen)
 766{
 767        struct child *newborn, **cradle;
 768
 769        newborn = xcalloc(1, sizeof(*newborn));
 770        live_children++;
 771        memcpy(&newborn->cld, cld, sizeof(*cld));
 772        memcpy(&newborn->address, addr, addrlen);
 773        for (cradle = &firstborn; *cradle; cradle = &(*cradle)->next)
 774                if (!addrcmp(&(*cradle)->address, &newborn->address))
 775                        break;
 776        newborn->next = *cradle;
 777        *cradle = newborn;
 778}
 779
 780/*
 781 * This gets called if the number of connections grows
 782 * past "max_connections".
 783 *
 784 * We kill the newest connection from a duplicate IP.
 785 */
 786static void kill_some_child(void)
 787{
 788        const struct child *blanket, *next;
 789
 790        if (!(blanket = firstborn))
 791                return;
 792
 793        for (; (next = blanket->next); blanket = next)
 794                if (!addrcmp(&blanket->address, &next->address)) {
 795                        kill(blanket->cld.pid, SIGTERM);
 796                        break;
 797                }
 798}
 799
 800static void check_dead_children(void)
 801{
 802        int status;
 803        pid_t pid;
 804
 805        struct child **cradle, *blanket;
 806        for (cradle = &firstborn; (blanket = *cradle);)
 807                if ((pid = waitpid(blanket->cld.pid, &status, WNOHANG)) > 1) {
 808                        const char *dead = "";
 809                        if (status)
 810                                dead = " (with error)";
 811                        loginfo("[%"PRIuMAX"] Disconnected%s", (uintmax_t)pid, dead);
 812
 813                        /* remove the child */
 814                        *cradle = blanket->next;
 815                        live_children--;
 816                        child_process_clear(&blanket->cld);
 817                        free(blanket);
 818                } else
 819                        cradle = &blanket->next;
 820}
 821
 822static struct argv_array cld_argv = ARGV_ARRAY_INIT;
 823static void handle(int incoming, struct sockaddr *addr, socklen_t addrlen)
 824{
 825        struct child_process cld = CHILD_PROCESS_INIT;
 826
 827        if (max_connections && live_children >= max_connections) {
 828                kill_some_child();
 829                sleep(1);  /* give it some time to die */
 830                check_dead_children();
 831                if (live_children >= max_connections) {
 832                        close(incoming);
 833                        logerror("Too many children, dropping connection");
 834                        return;
 835                }
 836        }
 837
 838        if (addr->sa_family == AF_INET) {
 839                char buf[128] = "";
 840                struct sockaddr_in *sin_addr = (void *) addr;
 841                inet_ntop(addr->sa_family, &sin_addr->sin_addr, buf, sizeof(buf));
 842                argv_array_pushf(&cld.env_array, "REMOTE_ADDR=%s", buf);
 843                argv_array_pushf(&cld.env_array, "REMOTE_PORT=%d",
 844                                 ntohs(sin_addr->sin_port));
 845#ifndef NO_IPV6
 846        } else if (addr->sa_family == AF_INET6) {
 847                char buf[128] = "";
 848                struct sockaddr_in6 *sin6_addr = (void *) addr;
 849                inet_ntop(AF_INET6, &sin6_addr->sin6_addr, buf, sizeof(buf));
 850                argv_array_pushf(&cld.env_array, "REMOTE_ADDR=[%s]", buf);
 851                argv_array_pushf(&cld.env_array, "REMOTE_PORT=%d",
 852                                 ntohs(sin6_addr->sin6_port));
 853#endif
 854        }
 855
 856        cld.argv = cld_argv.argv;
 857        cld.in = incoming;
 858        cld.out = dup(incoming);
 859
 860        if (start_command(&cld))
 861                logerror("unable to fork");
 862        else
 863                add_child(&cld, addr, addrlen);
 864}
 865
 866static void child_handler(int signo)
 867{
 868        /*
 869         * Otherwise empty handler because systemcalls will get interrupted
 870         * upon signal receipt
 871         * SysV needs the handler to be rearmed
 872         */
 873        signal(SIGCHLD, child_handler);
 874}
 875
 876static int set_reuse_addr(int sockfd)
 877{
 878        int on = 1;
 879
 880        if (!reuseaddr)
 881                return 0;
 882        return setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
 883                          &on, sizeof(on));
 884}
 885
 886struct socketlist {
 887        int *list;
 888        size_t nr;
 889        size_t alloc;
 890};
 891
 892static const char *ip2str(int family, struct sockaddr *sin, socklen_t len)
 893{
 894#ifdef NO_IPV6
 895        static char ip[INET_ADDRSTRLEN];
 896#else
 897        static char ip[INET6_ADDRSTRLEN];
 898#endif
 899
 900        switch (family) {
 901#ifndef NO_IPV6
 902        case AF_INET6:
 903                inet_ntop(family, &((struct sockaddr_in6*)sin)->sin6_addr, ip, len);
 904                break;
 905#endif
 906        case AF_INET:
 907                inet_ntop(family, &((struct sockaddr_in*)sin)->sin_addr, ip, len);
 908                break;
 909        default:
 910                xsnprintf(ip, sizeof(ip), "<unknown>");
 911        }
 912        return ip;
 913}
 914
 915#ifndef NO_IPV6
 916
 917static int setup_named_sock(char *listen_addr, int listen_port, struct socketlist *socklist)
 918{
 919        int socknum = 0;
 920        char pbuf[NI_MAXSERV];
 921        struct addrinfo hints, *ai0, *ai;
 922        int gai;
 923        long flags;
 924
 925        xsnprintf(pbuf, sizeof(pbuf), "%d", listen_port);
 926        memset(&hints, 0, sizeof(hints));
 927        hints.ai_family = AF_UNSPEC;
 928        hints.ai_socktype = SOCK_STREAM;
 929        hints.ai_protocol = IPPROTO_TCP;
 930        hints.ai_flags = AI_PASSIVE;
 931
 932        gai = getaddrinfo(listen_addr, pbuf, &hints, &ai0);
 933        if (gai) {
 934                logerror("getaddrinfo() for %s failed: %s", listen_addr, gai_strerror(gai));
 935                return 0;
 936        }
 937
 938        for (ai = ai0; ai; ai = ai->ai_next) {
 939                int sockfd;
 940
 941                sockfd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
 942                if (sockfd < 0)
 943                        continue;
 944                if (sockfd >= FD_SETSIZE) {
 945                        logerror("Socket descriptor too large");
 946                        close(sockfd);
 947                        continue;
 948                }
 949
 950#ifdef IPV6_V6ONLY
 951                if (ai->ai_family == AF_INET6) {
 952                        int on = 1;
 953                        setsockopt(sockfd, IPPROTO_IPV6, IPV6_V6ONLY,
 954                                   &on, sizeof(on));
 955                        /* Note: error is not fatal */
 956                }
 957#endif
 958
 959                if (set_reuse_addr(sockfd)) {
 960                        logerror("Could not set SO_REUSEADDR: %s", strerror(errno));
 961                        close(sockfd);
 962                        continue;
 963                }
 964
 965                set_keep_alive(sockfd);
 966
 967                if (bind(sockfd, ai->ai_addr, ai->ai_addrlen) < 0) {
 968                        logerror("Could not bind 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                if (listen(sockfd, 5) < 0) {
 975                        logerror("Could not listen to %s: %s",
 976                                 ip2str(ai->ai_family, ai->ai_addr, ai->ai_addrlen),
 977                                 strerror(errno));
 978                        close(sockfd);
 979                        continue;       /* not fatal */
 980                }
 981
 982                flags = fcntl(sockfd, F_GETFD, 0);
 983                if (flags >= 0)
 984                        fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
 985
 986                ALLOC_GROW(socklist->list, socklist->nr + 1, socklist->alloc);
 987                socklist->list[socklist->nr++] = sockfd;
 988                socknum++;
 989        }
 990
 991        freeaddrinfo(ai0);
 992
 993        return socknum;
 994}
 995
 996#else /* NO_IPV6 */
 997
 998static int setup_named_sock(char *listen_addr, int listen_port, struct socketlist *socklist)
 999{
1000        struct sockaddr_in sin;
1001        int sockfd;
1002        long flags;
1003
1004        memset(&sin, 0, sizeof sin);
1005        sin.sin_family = AF_INET;
1006        sin.sin_port = htons(listen_port);
1007
1008        if (listen_addr) {
1009                /* Well, host better be an IP address here. */
1010                if (inet_pton(AF_INET, listen_addr, &sin.sin_addr.s_addr) <= 0)
1011                        return 0;
1012        } else {
1013                sin.sin_addr.s_addr = htonl(INADDR_ANY);
1014        }
1015
1016        sockfd = socket(AF_INET, SOCK_STREAM, 0);
1017        if (sockfd < 0)
1018                return 0;
1019
1020        if (set_reuse_addr(sockfd)) {
1021                logerror("Could not set SO_REUSEADDR: %s", strerror(errno));
1022                close(sockfd);
1023                return 0;
1024        }
1025
1026        set_keep_alive(sockfd);
1027
1028        if ( bind(sockfd, (struct sockaddr *)&sin, sizeof sin) < 0 ) {
1029                logerror("Could not bind to %s: %s",
1030                         ip2str(AF_INET, (struct sockaddr *)&sin, sizeof(sin)),
1031                         strerror(errno));
1032                close(sockfd);
1033                return 0;
1034        }
1035
1036        if (listen(sockfd, 5) < 0) {
1037                logerror("Could not listen to %s: %s",
1038                         ip2str(AF_INET, (struct sockaddr *)&sin, sizeof(sin)),
1039                         strerror(errno));
1040                close(sockfd);
1041                return 0;
1042        }
1043
1044        flags = fcntl(sockfd, F_GETFD, 0);
1045        if (flags >= 0)
1046                fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
1047
1048        ALLOC_GROW(socklist->list, socklist->nr + 1, socklist->alloc);
1049        socklist->list[socklist->nr++] = sockfd;
1050        return 1;
1051}
1052
1053#endif
1054
1055static void socksetup(struct string_list *listen_addr, int listen_port, struct socketlist *socklist)
1056{
1057        if (!listen_addr->nr)
1058                setup_named_sock(NULL, listen_port, socklist);
1059        else {
1060                int i, socknum;
1061                for (i = 0; i < listen_addr->nr; i++) {
1062                        socknum = setup_named_sock(listen_addr->items[i].string,
1063                                                   listen_port, socklist);
1064
1065                        if (socknum == 0)
1066                                logerror("unable to allocate any listen sockets for host %s on port %u",
1067                                         listen_addr->items[i].string, listen_port);
1068                }
1069        }
1070}
1071
1072static int service_loop(struct socketlist *socklist)
1073{
1074        struct pollfd *pfd;
1075        int i;
1076
1077        pfd = xcalloc(socklist->nr, sizeof(struct pollfd));
1078
1079        for (i = 0; i < socklist->nr; i++) {
1080                pfd[i].fd = socklist->list[i];
1081                pfd[i].events = POLLIN;
1082        }
1083
1084        signal(SIGCHLD, child_handler);
1085
1086        for (;;) {
1087                int i;
1088
1089                check_dead_children();
1090
1091                if (poll(pfd, socklist->nr, -1) < 0) {
1092                        if (errno != EINTR) {
1093                                logerror("Poll failed, resuming: %s",
1094                                      strerror(errno));
1095                                sleep(1);
1096                        }
1097                        continue;
1098                }
1099
1100                for (i = 0; i < socklist->nr; i++) {
1101                        if (pfd[i].revents & POLLIN) {
1102                                union {
1103                                        struct sockaddr sa;
1104                                        struct sockaddr_in sai;
1105#ifndef NO_IPV6
1106                                        struct sockaddr_in6 sai6;
1107#endif
1108                                } ss;
1109                                socklen_t sslen = sizeof(ss);
1110                                int incoming = accept(pfd[i].fd, &ss.sa, &sslen);
1111                                if (incoming < 0) {
1112                                        switch (errno) {
1113                                        case EAGAIN:
1114                                        case EINTR:
1115                                        case ECONNABORTED:
1116                                                continue;
1117                                        default:
1118                                                die_errno("accept returned");
1119                                        }
1120                                }
1121                                handle(incoming, &ss.sa, sslen);
1122                        }
1123                }
1124        }
1125}
1126
1127#ifdef NO_POSIX_GOODIES
1128
1129struct credentials;
1130
1131static void drop_privileges(struct credentials *cred)
1132{
1133        /* nothing */
1134}
1135
1136static struct credentials *prepare_credentials(const char *user_name,
1137    const char *group_name)
1138{
1139        die("--user not supported on this platform");
1140}
1141
1142#else
1143
1144struct credentials {
1145        struct passwd *pass;
1146        gid_t gid;
1147};
1148
1149static void drop_privileges(struct credentials *cred)
1150{
1151        if (cred && (initgroups(cred->pass->pw_name, cred->gid) ||
1152            setgid (cred->gid) || setuid(cred->pass->pw_uid)))
1153                die("cannot drop privileges");
1154}
1155
1156static struct credentials *prepare_credentials(const char *user_name,
1157    const char *group_name)
1158{
1159        static struct credentials c;
1160
1161        c.pass = getpwnam(user_name);
1162        if (!c.pass)
1163                die("user not found - %s", user_name);
1164
1165        if (!group_name)
1166                c.gid = c.pass->pw_gid;
1167        else {
1168                struct group *group = getgrnam(group_name);
1169                if (!group)
1170                        die("group not found - %s", group_name);
1171
1172                c.gid = group->gr_gid;
1173        }
1174
1175        return &c;
1176}
1177#endif
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 cmd_main(int argc, const 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        for (i = 1; i < argc; i++) {
1207                const char *arg = argv[i];
1208                const char *v;
1209
1210                if (skip_prefix(arg, "--listen=", &v)) {
1211                        string_list_append(&listen_addr, xstrdup_tolower(v));
1212                        continue;
1213                }
1214                if (skip_prefix(arg, "--port=", &v)) {
1215                        char *end;
1216                        unsigned long n;
1217                        n = strtoul(v, &end, 0);
1218                        if (*v && !*end) {
1219                                listen_port = n;
1220                                continue;
1221                        }
1222                }
1223                if (!strcmp(arg, "--serve")) {
1224                        serve_mode = 1;
1225                        continue;
1226                }
1227                if (!strcmp(arg, "--inetd")) {
1228                        inetd_mode = 1;
1229                        log_syslog = 1;
1230                        continue;
1231                }
1232                if (!strcmp(arg, "--verbose")) {
1233                        verbose = 1;
1234                        continue;
1235                }
1236                if (!strcmp(arg, "--syslog")) {
1237                        log_syslog = 1;
1238                        continue;
1239                }
1240                if (!strcmp(arg, "--export-all")) {
1241                        export_all_trees = 1;
1242                        continue;
1243                }
1244                if (skip_prefix(arg, "--access-hook=", &v)) {
1245                        access_hook = v;
1246                        continue;
1247                }
1248                if (skip_prefix(arg, "--timeout=", &v)) {
1249                        timeout = atoi(v);
1250                        continue;
1251                }
1252                if (skip_prefix(arg, "--init-timeout=", &v)) {
1253                        init_timeout = atoi(v);
1254                        continue;
1255                }
1256                if (skip_prefix(arg, "--max-connections=", &v)) {
1257                        max_connections = atoi(v);
1258                        if (max_connections < 0)
1259                                max_connections = 0;            /* unlimited */
1260                        continue;
1261                }
1262                if (!strcmp(arg, "--strict-paths")) {
1263                        strict_paths = 1;
1264                        continue;
1265                }
1266                if (skip_prefix(arg, "--base-path=", &v)) {
1267                        base_path = v;
1268                        continue;
1269                }
1270                if (!strcmp(arg, "--base-path-relaxed")) {
1271                        base_path_relaxed = 1;
1272                        continue;
1273                }
1274                if (skip_prefix(arg, "--interpolated-path=", &v)) {
1275                        interpolated_path = v;
1276                        continue;
1277                }
1278                if (!strcmp(arg, "--reuseaddr")) {
1279                        reuseaddr = 1;
1280                        continue;
1281                }
1282                if (!strcmp(arg, "--user-path")) {
1283                        user_path = "";
1284                        continue;
1285                }
1286                if (skip_prefix(arg, "--user-path=", &v)) {
1287                        user_path = v;
1288                        continue;
1289                }
1290                if (skip_prefix(arg, "--pid-file=", &v)) {
1291                        pid_file = v;
1292                        continue;
1293                }
1294                if (!strcmp(arg, "--detach")) {
1295                        detach = 1;
1296                        log_syslog = 1;
1297                        continue;
1298                }
1299                if (skip_prefix(arg, "--user=", &v)) {
1300                        user_name = v;
1301                        continue;
1302                }
1303                if (skip_prefix(arg, "--group=", &v)) {
1304                        group_name = v;
1305                        continue;
1306                }
1307                if (skip_prefix(arg, "--enable=", &v)) {
1308                        enable_service(v, 1);
1309                        continue;
1310                }
1311                if (skip_prefix(arg, "--disable=", &v)) {
1312                        enable_service(v, 0);
1313                        continue;
1314                }
1315                if (skip_prefix(arg, "--allow-override=", &v)) {
1316                        make_service_overridable(v, 1);
1317                        continue;
1318                }
1319                if (skip_prefix(arg, "--forbid-override=", &v)) {
1320                        make_service_overridable(v, 0);
1321                        continue;
1322                }
1323                if (!strcmp(arg, "--informative-errors")) {
1324                        informative_errors = 1;
1325                        continue;
1326                }
1327                if (!strcmp(arg, "--no-informative-errors")) {
1328                        informative_errors = 0;
1329                        continue;
1330                }
1331                if (!strcmp(arg, "--")) {
1332                        ok_paths = &argv[i+1];
1333                        break;
1334                } else if (arg[0] != '-') {
1335                        ok_paths = &argv[i];
1336                        break;
1337                }
1338
1339                usage(daemon_usage);
1340        }
1341
1342        if (log_syslog) {
1343                openlog("git-daemon", LOG_PID, LOG_DAEMON);
1344                set_die_routine(daemon_die);
1345        } else
1346                /* avoid splitting a message in the middle */
1347                setvbuf(stderr, NULL, _IOFBF, 4096);
1348
1349        if (inetd_mode && (detach || group_name || user_name))
1350                die("--detach, --user and --group are incompatible with --inetd");
1351
1352        if (inetd_mode && (listen_port || (listen_addr.nr > 0)))
1353                die("--listen= and --port= are incompatible with --inetd");
1354        else if (listen_port == 0)
1355                listen_port = DEFAULT_GIT_PORT;
1356
1357        if (group_name && !user_name)
1358                die("--group supplied without --user");
1359
1360        if (user_name)
1361                cred = prepare_credentials(user_name, group_name);
1362
1363        if (strict_paths && (!ok_paths || !*ok_paths))
1364                die("option --strict-paths requires a whitelist");
1365
1366        if (base_path && !is_directory(base_path))
1367                die("base-path '%s' does not exist or is not a directory",
1368                    base_path);
1369
1370        if (inetd_mode) {
1371                if (!freopen("/dev/null", "w", stderr))
1372                        die_errno("failed to redirect stderr to /dev/null");
1373        }
1374
1375        if (inetd_mode || serve_mode)
1376                return execute();
1377
1378        if (detach) {
1379                if (daemonize())
1380                        die("--detach not supported on this platform");
1381        }
1382
1383        if (pid_file)
1384                write_file(pid_file, "%"PRIuMAX, (uintmax_t) getpid());
1385
1386        /* prepare argv for serving-processes */
1387        argv_array_push(&cld_argv, argv[0]); /* git-daemon */
1388        argv_array_push(&cld_argv, "--serve");
1389        for (i = 1; i < argc; ++i)
1390                argv_array_push(&cld_argv, argv[i]);
1391
1392        return serve(&listen_addr, listen_port, cred);
1393}