Andrew's git / gitweb.git / daemon.c
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daemon.con commit Merge branch 'nd/doc-new-command' into maint (dcfb9d7)
   1#include "cache.h"
   2#include "pkt-line.h"
   3#include "exec_cmd.h"
   4#include "run-command.h"
   5#include "strbuf.h"
   6#include "string-list.h"
   7
   8#ifndef HOST_NAME_MAX
   9#define HOST_NAME_MAX 256
  10#endif
  11
  12#ifdef NO_INITGROUPS
  13#define initgroups(x, y) (0) /* nothing */
  14#endif
  15
  16static int log_syslog;
  17static int verbose;
  18static int reuseaddr;
  19static int informative_errors;
  20
  21static const char daemon_usage[] =
  22"git daemon [--verbose] [--syslog] [--export-all]\n"
  23"           [--timeout=<n>] [--init-timeout=<n>] [--max-connections=<n>]\n"
  24"           [--strict-paths] [--base-path=<path>] [--base-path-relaxed]\n"
  25"           [--user-path | --user-path=<path>]\n"
  26"           [--interpolated-path=<path>]\n"
  27"           [--reuseaddr] [--pid-file=<file>]\n"
  28"           [--(enable|disable|allow-override|forbid-override)=<service>]\n"
  29"           [--access-hook=<path>]\n"
  30"           [--inetd | [--listen=<host_or_ipaddr>] [--port=<n>]\n"
  31"                      [--detach] [--user=<user> [--group=<group>]]\n"
  32"           [<directory>...]";
  33
  34/* List of acceptable pathname prefixes */
  35static char **ok_paths;
  36static int strict_paths;
  37
  38/* If this is set, git-daemon-export-ok is not required */
  39static int export_all_trees;
  40
  41/* Take all paths relative to this one if non-NULL */
  42static const char *base_path;
  43static const char *interpolated_path;
  44static int base_path_relaxed;
  45
  46/* If defined, ~user notation is allowed and the string is inserted
  47 * after ~user/.  E.g. a request to git://host/~alice/frotz would
  48 * go to /home/alice/pub_git/frotz with --user-path=pub_git.
  49 */
  50static const char *user_path;
  51
  52/* Timeout, and initial timeout */
  53static unsigned int timeout;
  54static unsigned int init_timeout;
  55
  56struct hostinfo {
  57        struct strbuf hostname;
  58        struct strbuf canon_hostname;
  59        struct strbuf ip_address;
  60        struct strbuf tcp_port;
  61        unsigned int hostname_lookup_done:1;
  62        unsigned int saw_extended_args:1;
  63};
  64
  65static void lookup_hostname(struct hostinfo *hi);
  66
  67static const char *get_canon_hostname(struct hostinfo *hi)
  68{
  69        lookup_hostname(hi);
  70        return hi->canon_hostname.buf;
  71}
  72
  73static const char *get_ip_address(struct hostinfo *hi)
  74{
  75        lookup_hostname(hi);
  76        return hi->ip_address.buf;
  77}
  78
  79static void logreport(int priority, const char *err, va_list params)
  80{
  81        if (log_syslog) {
  82                char buf[1024];
  83                vsnprintf(buf, sizeof(buf), err, params);
  84                syslog(priority, "%s", buf);
  85        } else {
  86                /*
  87                 * Since stderr is set to buffered mode, the
  88                 * logging of different processes will not overlap
  89                 * unless they overflow the (rather big) buffers.
  90                 */
  91                fprintf(stderr, "[%"PRIuMAX"] ", (uintmax_t)getpid());
  92                vfprintf(stderr, err, params);
  93                fputc('\n', stderr);
  94                fflush(stderr);
  95        }
  96}
  97
  98__attribute__((format (printf, 1, 2)))
  99static void logerror(const char *err, ...)
 100{
 101        va_list params;
 102        va_start(params, err);
 103        logreport(LOG_ERR, err, params);
 104        va_end(params);
 105}
 106
 107__attribute__((format (printf, 1, 2)))
 108static void loginfo(const char *err, ...)
 109{
 110        va_list params;
 111        if (!verbose)
 112                return;
 113        va_start(params, err);
 114        logreport(LOG_INFO, err, params);
 115        va_end(params);
 116}
 117
 118static void NORETURN daemon_die(const char *err, va_list params)
 119{
 120        logreport(LOG_ERR, err, params);
 121        exit(1);
 122}
 123
 124struct expand_path_context {
 125        const char *directory;
 126        struct hostinfo *hostinfo;
 127};
 128
 129static size_t expand_path(struct strbuf *sb, const char *placeholder, void *ctx)
 130{
 131        struct expand_path_context *context = ctx;
 132        struct hostinfo *hi = context->hostinfo;
 133
 134        switch (placeholder[0]) {
 135        case 'H':
 136                strbuf_addbuf(sb, &hi->hostname);
 137                return 1;
 138        case 'C':
 139                if (placeholder[1] == 'H') {
 140                        strbuf_addstr(sb, get_canon_hostname(hi));
 141                        return 2;
 142                }
 143                break;
 144        case 'I':
 145                if (placeholder[1] == 'P') {
 146                        strbuf_addstr(sb, get_ip_address(hi));
 147                        return 2;
 148                }
 149                break;
 150        case 'P':
 151                strbuf_addbuf(sb, &hi->tcp_port);
 152                return 1;
 153        case 'D':
 154                strbuf_addstr(sb, context->directory);
 155                return 1;
 156        }
 157        return 0;
 158}
 159
 160static const char *path_ok(const char *directory, struct hostinfo *hi)
 161{
 162        static char rpath[PATH_MAX];
 163        static char interp_path[PATH_MAX];
 164        const char *path;
 165        const char *dir;
 166
 167        dir = directory;
 168
 169        if (daemon_avoid_alias(dir)) {
 170                logerror("'%s': aliased", dir);
 171                return NULL;
 172        }
 173
 174        if (*dir == '~') {
 175                if (!user_path) {
 176                        logerror("'%s': User-path not allowed", dir);
 177                        return NULL;
 178                }
 179                if (*user_path) {
 180                        /* Got either "~alice" or "~alice/foo";
 181                         * rewrite them to "~alice/%s" or
 182                         * "~alice/%s/foo".
 183                         */
 184                        int namlen, restlen = strlen(dir);
 185                        const char *slash = strchr(dir, '/');
 186                        if (!slash)
 187                                slash = dir + restlen;
 188                        namlen = slash - dir;
 189                        restlen -= namlen;
 190                        loginfo("userpath <%s>, request <%s>, namlen %d, restlen %d, slash <%s>", user_path, dir, namlen, restlen, slash);
 191                        snprintf(rpath, PATH_MAX, "%.*s/%s%.*s",
 192                                 namlen, dir, user_path, restlen, slash);
 193                        dir = rpath;
 194                }
 195        }
 196        else if (interpolated_path && hi->saw_extended_args) {
 197                struct strbuf expanded_path = STRBUF_INIT;
 198                struct expand_path_context context;
 199
 200                context.directory = directory;
 201                context.hostinfo = hi;
 202
 203                if (*dir != '/') {
 204                        /* Allow only absolute */
 205                        logerror("'%s': Non-absolute path denied (interpolated-path active)", dir);
 206                        return NULL;
 207                }
 208
 209                strbuf_expand(&expanded_path, interpolated_path,
 210                              expand_path, &context);
 211                strlcpy(interp_path, expanded_path.buf, PATH_MAX);
 212                strbuf_release(&expanded_path);
 213                loginfo("Interpolated dir '%s'", interp_path);
 214
 215                dir = interp_path;
 216        }
 217        else if (base_path) {
 218                if (*dir != '/') {
 219                        /* Allow only absolute */
 220                        logerror("'%s': Non-absolute path denied (base-path active)", dir);
 221                        return NULL;
 222                }
 223                snprintf(rpath, PATH_MAX, "%s%s", base_path, dir);
 224                dir = rpath;
 225        }
 226
 227        path = enter_repo(dir, strict_paths);
 228        if (!path && base_path && base_path_relaxed) {
 229                /*
 230                 * if we fail and base_path_relaxed is enabled, try without
 231                 * prefixing the base path
 232                 */
 233                dir = directory;
 234                path = enter_repo(dir, strict_paths);
 235        }
 236
 237        if (!path) {
 238                logerror("'%s' does not appear to be a git repository", dir);
 239                return NULL;
 240        }
 241
 242        if ( ok_paths && *ok_paths ) {
 243                char **pp;
 244                int pathlen = strlen(path);
 245
 246                /* The validation is done on the paths after enter_repo
 247                 * appends optional {.git,.git/.git} and friends, but
 248                 * it does not use getcwd().  So if your /pub is
 249                 * a symlink to /mnt/pub, you can whitelist /pub and
 250                 * do not have to say /mnt/pub.
 251                 * Do not say /pub/.
 252                 */
 253                for ( pp = ok_paths ; *pp ; pp++ ) {
 254                        int len = strlen(*pp);
 255                        if (len <= pathlen &&
 256                            !memcmp(*pp, path, len) &&
 257                            (path[len] == '\0' ||
 258                             (!strict_paths && path[len] == '/')))
 259                                return path;
 260                }
 261        }
 262        else {
 263                /* be backwards compatible */
 264                if (!strict_paths)
 265                        return path;
 266        }
 267
 268        logerror("'%s': not in whitelist", path);
 269        return NULL;            /* Fallthrough. Deny by default */
 270}
 271
 272typedef int (*daemon_service_fn)(void);
 273struct daemon_service {
 274        const char *name;
 275        const char *config_name;
 276        daemon_service_fn fn;
 277        int enabled;
 278        int overridable;
 279};
 280
 281static int daemon_error(const char *dir, const char *msg)
 282{
 283        if (!informative_errors)
 284                msg = "access denied or repository not exported";
 285        packet_write(1, "ERR %s: %s", msg, dir);
 286        return -1;
 287}
 288
 289static const char *access_hook;
 290
 291static int run_access_hook(struct daemon_service *service, const char *dir,
 292                           const char *path, struct hostinfo *hi)
 293{
 294        struct child_process child = CHILD_PROCESS_INIT;
 295        struct strbuf buf = STRBUF_INIT;
 296        const char *argv[8];
 297        const char **arg = argv;
 298        char *eol;
 299        int seen_errors = 0;
 300
 301        *arg++ = access_hook;
 302        *arg++ = service->name;
 303        *arg++ = path;
 304        *arg++ = hi->hostname.buf;
 305        *arg++ = get_canon_hostname(hi);
 306        *arg++ = get_ip_address(hi);
 307        *arg++ = hi->tcp_port.buf;
 308        *arg = NULL;
 309
 310        child.use_shell = 1;
 311        child.argv = argv;
 312        child.no_stdin = 1;
 313        child.no_stderr = 1;
 314        child.out = -1;
 315        if (start_command(&child)) {
 316                logerror("daemon access hook '%s' failed to start",
 317                         access_hook);
 318                goto error_return;
 319        }
 320        if (strbuf_read(&buf, child.out, 0) < 0) {
 321                logerror("failed to read from pipe to daemon access hook '%s'",
 322                         access_hook);
 323                strbuf_reset(&buf);
 324                seen_errors = 1;
 325        }
 326        if (close(child.out) < 0) {
 327                logerror("failed to close pipe to daemon access hook '%s'",
 328                         access_hook);
 329                seen_errors = 1;
 330        }
 331        if (finish_command(&child))
 332                seen_errors = 1;
 333
 334        if (!seen_errors) {
 335                strbuf_release(&buf);
 336                return 0;
 337        }
 338
 339error_return:
 340        strbuf_ltrim(&buf);
 341        if (!buf.len)
 342                strbuf_addstr(&buf, "service rejected");
 343        eol = strchr(buf.buf, '\n');
 344        if (eol)
 345                *eol = '\0';
 346        errno = EACCES;
 347        daemon_error(dir, buf.buf);
 348        strbuf_release(&buf);
 349        return -1;
 350}
 351
 352static int run_service(const char *dir, struct daemon_service *service,
 353                       struct hostinfo *hi)
 354{
 355        const char *path;
 356        int enabled = service->enabled;
 357        struct strbuf var = STRBUF_INIT;
 358
 359        loginfo("Request %s for '%s'", service->name, dir);
 360
 361        if (!enabled && !service->overridable) {
 362                logerror("'%s': service not enabled.", service->name);
 363                errno = EACCES;
 364                return daemon_error(dir, "service not enabled");
 365        }
 366
 367        if (!(path = path_ok(dir, hi)))
 368                return daemon_error(dir, "no such repository");
 369
 370        /*
 371         * Security on the cheap.
 372         *
 373         * We want a readable HEAD, usable "objects" directory, and
 374         * a "git-daemon-export-ok" flag that says that the other side
 375         * is ok with us doing this.
 376         *
 377         * path_ok() uses enter_repo() and does whitelist checking.
 378         * We only need to make sure the repository is exported.
 379         */
 380
 381        if (!export_all_trees && access("git-daemon-export-ok", F_OK)) {
 382                logerror("'%s': repository not exported.", path);
 383                errno = EACCES;
 384                return daemon_error(dir, "repository not exported");
 385        }
 386
 387        if (service->overridable) {
 388                strbuf_addf(&var, "daemon.%s", service->config_name);
 389                git_config_get_bool(var.buf, &enabled);
 390                strbuf_release(&var);
 391        }
 392        if (!enabled) {
 393                logerror("'%s': service not enabled for '%s'",
 394                         service->name, path);
 395                errno = EACCES;
 396                return daemon_error(dir, "service not enabled");
 397        }
 398
 399        /*
 400         * Optionally, a hook can choose to deny access to the
 401         * repository depending on the phase of the moon.
 402         */
 403        if (access_hook && run_access_hook(service, dir, path, hi))
 404                return -1;
 405
 406        /*
 407         * We'll ignore SIGTERM from now on, we have a
 408         * good client.
 409         */
 410        signal(SIGTERM, SIG_IGN);
 411
 412        return service->fn();
 413}
 414
 415static void copy_to_log(int fd)
 416{
 417        struct strbuf line = STRBUF_INIT;
 418        FILE *fp;
 419
 420        fp = fdopen(fd, "r");
 421        if (fp == NULL) {
 422                logerror("fdopen of error channel failed");
 423                close(fd);
 424                return;
 425        }
 426
 427        while (strbuf_getline_lf(&line, fp) != EOF) {
 428                logerror("%s", line.buf);
 429                strbuf_setlen(&line, 0);
 430        }
 431
 432        strbuf_release(&line);
 433        fclose(fp);
 434}
 435
 436static int run_service_command(const char **argv)
 437{
 438        struct child_process cld = CHILD_PROCESS_INIT;
 439
 440        cld.argv = argv;
 441        cld.git_cmd = 1;
 442        cld.err = -1;
 443        if (start_command(&cld))
 444                return -1;
 445
 446        close(0);
 447        close(1);
 448
 449        copy_to_log(cld.err);
 450
 451        return finish_command(&cld);
 452}
 453
 454static int upload_pack(void)
 455{
 456        /* Timeout as string */
 457        char timeout_buf[64];
 458        const char *argv[] = { "upload-pack", "--strict", NULL, ".", NULL };
 459
 460        argv[2] = timeout_buf;
 461
 462        snprintf(timeout_buf, sizeof timeout_buf, "--timeout=%u", timeout);
 463        return run_service_command(argv);
 464}
 465
 466static int upload_archive(void)
 467{
 468        static const char *argv[] = { "upload-archive", ".", NULL };
 469        return run_service_command(argv);
 470}
 471
 472static int receive_pack(void)
 473{
 474        static const char *argv[] = { "receive-pack", ".", NULL };
 475        return run_service_command(argv);
 476}
 477
 478static struct daemon_service daemon_service[] = {
 479        { "upload-archive", "uploadarch", upload_archive, 0, 1 },
 480        { "upload-pack", "uploadpack", upload_pack, 1, 1 },
 481        { "receive-pack", "receivepack", receive_pack, 0, 1 },
 482};
 483
 484static void enable_service(const char *name, int ena)
 485{
 486        int i;
 487        for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 488                if (!strcmp(daemon_service[i].name, name)) {
 489                        daemon_service[i].enabled = ena;
 490                        return;
 491                }
 492        }
 493        die("No such service %s", name);
 494}
 495
 496static void make_service_overridable(const char *name, int ena)
 497{
 498        int i;
 499        for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 500                if (!strcmp(daemon_service[i].name, name)) {
 501                        daemon_service[i].overridable = ena;
 502                        return;
 503                }
 504        }
 505        die("No such service %s", name);
 506}
 507
 508static void parse_host_and_port(char *hostport, char **host,
 509        char **port)
 510{
 511        if (*hostport == '[') {
 512                char *end;
 513
 514                end = strchr(hostport, ']');
 515                if (!end)
 516                        die("Invalid request ('[' without ']')");
 517                *end = '\0';
 518                *host = hostport + 1;
 519                if (!end[1])
 520                        *port = NULL;
 521                else if (end[1] == ':')
 522                        *port = end + 2;
 523                else
 524                        die("Garbage after end of host part");
 525        } else {
 526                *host = hostport;
 527                *port = strrchr(hostport, ':');
 528                if (*port) {
 529                        **port = '\0';
 530                        ++*port;
 531                }
 532        }
 533}
 534
 535/*
 536 * Sanitize a string from the client so that it's OK to be inserted into a
 537 * filesystem path. Specifically, we disallow slashes, runs of "..", and
 538 * trailing and leading dots, which means that the client cannot escape
 539 * our base path via ".." traversal.
 540 */
 541static void sanitize_client(struct strbuf *out, const char *in)
 542{
 543        for (; *in; in++) {
 544                if (*in == '/')
 545                        continue;
 546                if (*in == '.' && (!out->len || out->buf[out->len - 1] == '.'))
 547                        continue;
 548                strbuf_addch(out, *in);
 549        }
 550
 551        while (out->len && out->buf[out->len - 1] == '.')
 552                strbuf_setlen(out, out->len - 1);
 553}
 554
 555/*
 556 * Like sanitize_client, but we also perform any canonicalization
 557 * to make life easier on the admin.
 558 */
 559static void canonicalize_client(struct strbuf *out, const char *in)
 560{
 561        sanitize_client(out, in);
 562        strbuf_tolower(out);
 563}
 564
 565/*
 566 * Read the host as supplied by the client connection.
 567 */
 568static void parse_host_arg(struct hostinfo *hi, char *extra_args, int buflen)
 569{
 570        char *val;
 571        int vallen;
 572        char *end = extra_args + buflen;
 573
 574        if (extra_args < end && *extra_args) {
 575                hi->saw_extended_args = 1;
 576                if (strncasecmp("host=", extra_args, 5) == 0) {
 577                        val = extra_args + 5;
 578                        vallen = strlen(val) + 1;
 579                        if (*val) {
 580                                /* Split <host>:<port> at colon. */
 581                                char *host;
 582                                char *port;
 583                                parse_host_and_port(val, &host, &port);
 584                                if (port)
 585                                        sanitize_client(&hi->tcp_port, port);
 586                                canonicalize_client(&hi->hostname, host);
 587                                hi->hostname_lookup_done = 0;
 588                        }
 589
 590                        /* On to the next one */
 591                        extra_args = val + vallen;
 592                }
 593                if (extra_args < end && *extra_args)
 594                        die("Invalid request");
 595        }
 596}
 597
 598/*
 599 * Locate canonical hostname and its IP address.
 600 */
 601static void lookup_hostname(struct hostinfo *hi)
 602{
 603        if (!hi->hostname_lookup_done && hi->hostname.len) {
 604#ifndef NO_IPV6
 605                struct addrinfo hints;
 606                struct addrinfo *ai;
 607                int gai;
 608                static char addrbuf[HOST_NAME_MAX + 1];
 609
 610                memset(&hints, 0, sizeof(hints));
 611                hints.ai_flags = AI_CANONNAME;
 612
 613                gai = getaddrinfo(hi->hostname.buf, NULL, &hints, &ai);
 614                if (!gai) {
 615                        struct sockaddr_in *sin_addr = (void *)ai->ai_addr;
 616
 617                        inet_ntop(AF_INET, &sin_addr->sin_addr,
 618                                  addrbuf, sizeof(addrbuf));
 619                        strbuf_addstr(&hi->ip_address, addrbuf);
 620
 621                        if (ai->ai_canonname)
 622                                sanitize_client(&hi->canon_hostname,
 623                                                ai->ai_canonname);
 624                        else
 625                                strbuf_addbuf(&hi->canon_hostname,
 626                                              &hi->ip_address);
 627
 628                        freeaddrinfo(ai);
 629                }
 630#else
 631                struct hostent *hent;
 632                struct sockaddr_in sa;
 633                char **ap;
 634                static char addrbuf[HOST_NAME_MAX + 1];
 635
 636                hent = gethostbyname(hi->hostname.buf);
 637                if (hent) {
 638                        ap = hent->h_addr_list;
 639                        memset(&sa, 0, sizeof sa);
 640                        sa.sin_family = hent->h_addrtype;
 641                        sa.sin_port = htons(0);
 642                        memcpy(&sa.sin_addr, *ap, hent->h_length);
 643
 644                        inet_ntop(hent->h_addrtype, &sa.sin_addr,
 645                                  addrbuf, sizeof(addrbuf));
 646
 647                        sanitize_client(&hi->canon_hostname, hent->h_name);
 648                        strbuf_addstr(&hi->ip_address, addrbuf);
 649                }
 650#endif
 651                hi->hostname_lookup_done = 1;
 652        }
 653}
 654
 655static void hostinfo_init(struct hostinfo *hi)
 656{
 657        memset(hi, 0, sizeof(*hi));
 658        strbuf_init(&hi->hostname, 0);
 659        strbuf_init(&hi->canon_hostname, 0);
 660        strbuf_init(&hi->ip_address, 0);
 661        strbuf_init(&hi->tcp_port, 0);
 662}
 663
 664static void hostinfo_clear(struct hostinfo *hi)
 665{
 666        strbuf_release(&hi->hostname);
 667        strbuf_release(&hi->canon_hostname);
 668        strbuf_release(&hi->ip_address);
 669        strbuf_release(&hi->tcp_port);
 670}
 671
 672static void set_keep_alive(int sockfd)
 673{
 674        int ka = 1;
 675
 676        if (setsockopt(sockfd, SOL_SOCKET, SO_KEEPALIVE, &ka, sizeof(ka)) < 0)
 677                logerror("unable to set SO_KEEPALIVE on socket: %s",
 678                        strerror(errno));
 679}
 680
 681static int execute(void)
 682{
 683        char *line = packet_buffer;
 684        int pktlen, len, i;
 685        char *addr = getenv("REMOTE_ADDR"), *port = getenv("REMOTE_PORT");
 686        struct hostinfo hi;
 687
 688        hostinfo_init(&hi);
 689
 690        if (addr)
 691                loginfo("Connection from %s:%s", addr, port);
 692
 693        set_keep_alive(0);
 694        alarm(init_timeout ? init_timeout : timeout);
 695        pktlen = packet_read(0, NULL, NULL, packet_buffer, sizeof(packet_buffer), 0);
 696        alarm(0);
 697
 698        len = strlen(line);
 699        if (pktlen != len)
 700                loginfo("Extended attributes (%d bytes) exist <%.*s>",
 701                        (int) pktlen - len,
 702                        (int) pktlen - len, line + len + 1);
 703        if (len && line[len-1] == '\n') {
 704                line[--len] = 0;
 705                pktlen--;
 706        }
 707
 708        if (len != pktlen)
 709                parse_host_arg(&hi, line + len + 1, pktlen - len - 1);
 710
 711        for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 712                struct daemon_service *s = &(daemon_service[i]);
 713                const char *arg;
 714
 715                if (skip_prefix(line, "git-", &arg) &&
 716                    skip_prefix(arg, s->name, &arg) &&
 717                    *arg++ == ' ') {
 718                        /*
 719                         * Note: The directory here is probably context sensitive,
 720                         * and might depend on the actual service being performed.
 721                         */
 722                        int rc = run_service(arg, s, &hi);
 723                        hostinfo_clear(&hi);
 724                        return rc;
 725                }
 726        }
 727
 728        hostinfo_clear(&hi);
 729        logerror("Protocol error: '%s'", line);
 730        return -1;
 731}
 732
 733static int addrcmp(const struct sockaddr_storage *s1,
 734    const struct sockaddr_storage *s2)
 735{
 736        const struct sockaddr *sa1 = (const struct sockaddr*) s1;
 737        const struct sockaddr *sa2 = (const struct sockaddr*) s2;
 738
 739        if (sa1->sa_family != sa2->sa_family)
 740                return sa1->sa_family - sa2->sa_family;
 741        if (sa1->sa_family == AF_INET)
 742                return memcmp(&((struct sockaddr_in *)s1)->sin_addr,
 743                    &((struct sockaddr_in *)s2)->sin_addr,
 744                    sizeof(struct in_addr));
 745#ifndef NO_IPV6
 746        if (sa1->sa_family == AF_INET6)
 747                return memcmp(&((struct sockaddr_in6 *)s1)->sin6_addr,
 748                    &((struct sockaddr_in6 *)s2)->sin6_addr,
 749                    sizeof(struct in6_addr));
 750#endif
 751        return 0;
 752}
 753
 754static int max_connections = 32;
 755
 756static unsigned int live_children;
 757
 758static struct child {
 759        struct child *next;
 760        struct child_process cld;
 761        struct sockaddr_storage address;
 762} *firstborn;
 763
 764static void add_child(struct child_process *cld, struct sockaddr *addr, socklen_t addrlen)
 765{
 766        struct child *newborn, **cradle;
 767
 768        newborn = xcalloc(1, sizeof(*newborn));
 769        live_children++;
 770        memcpy(&newborn->cld, cld, sizeof(*cld));
 771        memcpy(&newborn->address, addr, addrlen);
 772        for (cradle = &firstborn; *cradle; cradle = &(*cradle)->next)
 773                if (!addrcmp(&(*cradle)->address, &newborn->address))
 774                        break;
 775        newborn->next = *cradle;
 776        *cradle = newborn;
 777}
 778
 779/*
 780 * This gets called if the number of connections grows
 781 * past "max_connections".
 782 *
 783 * We kill the newest connection from a duplicate IP.
 784 */
 785static void kill_some_child(void)
 786{
 787        const struct child *blanket, *next;
 788
 789        if (!(blanket = firstborn))
 790                return;
 791
 792        for (; (next = blanket->next); blanket = next)
 793                if (!addrcmp(&blanket->address, &next->address)) {
 794                        kill(blanket->cld.pid, SIGTERM);
 795                        break;
 796                }
 797}
 798
 799static void check_dead_children(void)
 800{
 801        int status;
 802        pid_t pid;
 803
 804        struct child **cradle, *blanket;
 805        for (cradle = &firstborn; (blanket = *cradle);)
 806                if ((pid = waitpid(blanket->cld.pid, &status, WNOHANG)) > 1) {
 807                        const char *dead = "";
 808                        if (status)
 809                                dead = " (with error)";
 810                        loginfo("[%"PRIuMAX"] Disconnected%s", (uintmax_t)pid, dead);
 811
 812                        /* remove the child */
 813                        *cradle = blanket->next;
 814                        live_children--;
 815                        child_process_clear(&blanket->cld);
 816                        free(blanket);
 817                } else
 818                        cradle = &blanket->next;
 819}
 820
 821static struct argv_array cld_argv = ARGV_ARRAY_INIT;
 822static void handle(int incoming, struct sockaddr *addr, socklen_t addrlen)
 823{
 824        struct child_process cld = CHILD_PROCESS_INIT;
 825
 826        if (max_connections && live_children >= max_connections) {
 827                kill_some_child();
 828                sleep(1);  /* give it some time to die */
 829                check_dead_children();
 830                if (live_children >= max_connections) {
 831                        close(incoming);
 832                        logerror("Too many children, dropping connection");
 833                        return;
 834                }
 835        }
 836
 837        if (addr->sa_family == AF_INET) {
 838                char buf[128] = "";
 839                struct sockaddr_in *sin_addr = (void *) addr;
 840                inet_ntop(addr->sa_family, &sin_addr->sin_addr, buf, sizeof(buf));
 841                argv_array_pushf(&cld.env_array, "REMOTE_ADDR=%s", buf);
 842                argv_array_pushf(&cld.env_array, "REMOTE_PORT=%d",
 843                                 ntohs(sin_addr->sin_port));
 844#ifndef NO_IPV6
 845        } else if (addr->sa_family == AF_INET6) {
 846                char buf[128] = "";
 847                struct sockaddr_in6 *sin6_addr = (void *) addr;
 848                inet_ntop(AF_INET6, &sin6_addr->sin6_addr, buf, sizeof(buf));
 849                argv_array_pushf(&cld.env_array, "REMOTE_ADDR=[%s]", buf);
 850                argv_array_pushf(&cld.env_array, "REMOTE_PORT=%d",
 851                                 ntohs(sin6_addr->sin6_port));
 852#endif
 853        }
 854
 855        cld.argv = cld_argv.argv;
 856        cld.in = incoming;
 857        cld.out = dup(incoming);
 858
 859        if (start_command(&cld))
 860                logerror("unable to fork");
 861        else
 862                add_child(&cld, addr, addrlen);
 863}
 864
 865static void child_handler(int signo)
 866{
 867        /*
 868         * Otherwise empty handler because systemcalls will get interrupted
 869         * upon signal receipt
 870         * SysV needs the handler to be rearmed
 871         */
 872        signal(SIGCHLD, child_handler);
 873}
 874
 875static int set_reuse_addr(int sockfd)
 876{
 877        int on = 1;
 878
 879        if (!reuseaddr)
 880                return 0;
 881        return setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
 882                          &on, sizeof(on));
 883}
 884
 885struct socketlist {
 886        int *list;
 887        size_t nr;
 888        size_t alloc;
 889};
 890
 891static const char *ip2str(int family, struct sockaddr *sin, socklen_t len)
 892{
 893#ifdef NO_IPV6
 894        static char ip[INET_ADDRSTRLEN];
 895#else
 896        static char ip[INET6_ADDRSTRLEN];
 897#endif
 898
 899        switch (family) {
 900#ifndef NO_IPV6
 901        case AF_INET6:
 902                inet_ntop(family, &((struct sockaddr_in6*)sin)->sin6_addr, ip, len);
 903                break;
 904#endif
 905        case AF_INET:
 906                inet_ntop(family, &((struct sockaddr_in*)sin)->sin_addr, ip, len);
 907                break;
 908        default:
 909                xsnprintf(ip, sizeof(ip), "<unknown>");
 910        }
 911        return ip;
 912}
 913
 914#ifndef NO_IPV6
 915
 916static int setup_named_sock(char *listen_addr, int listen_port, struct socketlist *socklist)
 917{
 918        int socknum = 0;
 919        char pbuf[NI_MAXSERV];
 920        struct addrinfo hints, *ai0, *ai;
 921        int gai;
 922        long flags;
 923
 924        xsnprintf(pbuf, sizeof(pbuf), "%d", listen_port);
 925        memset(&hints, 0, sizeof(hints));
 926        hints.ai_family = AF_UNSPEC;
 927        hints.ai_socktype = SOCK_STREAM;
 928        hints.ai_protocol = IPPROTO_TCP;
 929        hints.ai_flags = AI_PASSIVE;
 930
 931        gai = getaddrinfo(listen_addr, pbuf, &hints, &ai0);
 932        if (gai) {
 933                logerror("getaddrinfo() for %s failed: %s", listen_addr, gai_strerror(gai));
 934                return 0;
 935        }
 936
 937        for (ai = ai0; ai; ai = ai->ai_next) {
 938                int sockfd;
 939
 940                sockfd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
 941                if (sockfd < 0)
 942                        continue;
 943                if (sockfd >= FD_SETSIZE) {
 944                        logerror("Socket descriptor too large");
 945                        close(sockfd);
 946                        continue;
 947                }
 948
 949#ifdef IPV6_V6ONLY
 950                if (ai->ai_family == AF_INET6) {
 951                        int on = 1;
 952                        setsockopt(sockfd, IPPROTO_IPV6, IPV6_V6ONLY,
 953                                   &on, sizeof(on));
 954                        /* Note: error is not fatal */
 955                }
 956#endif
 957
 958                if (set_reuse_addr(sockfd)) {
 959                        logerror("Could not set SO_REUSEADDR: %s", strerror(errno));
 960                        close(sockfd);
 961                        continue;
 962                }
 963
 964                set_keep_alive(sockfd);
 965
 966                if (bind(sockfd, ai->ai_addr, ai->ai_addrlen) < 0) {
 967                        logerror("Could not bind to %s: %s",
 968                                 ip2str(ai->ai_family, ai->ai_addr, ai->ai_addrlen),
 969                                 strerror(errno));
 970                        close(sockfd);
 971                        continue;       /* not fatal */
 972                }
 973                if (listen(sockfd, 5) < 0) {
 974                        logerror("Could not listen to %s: %s",
 975                                 ip2str(ai->ai_family, ai->ai_addr, ai->ai_addrlen),
 976                                 strerror(errno));
 977                        close(sockfd);
 978                        continue;       /* not fatal */
 979                }
 980
 981                flags = fcntl(sockfd, F_GETFD, 0);
 982                if (flags >= 0)
 983                        fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
 984
 985                ALLOC_GROW(socklist->list, socklist->nr + 1, socklist->alloc);
 986                socklist->list[socklist->nr++] = sockfd;
 987                socknum++;
 988        }
 989
 990        freeaddrinfo(ai0);
 991
 992        return socknum;
 993}
 994
 995#else /* NO_IPV6 */
 996
 997static int setup_named_sock(char *listen_addr, int listen_port, struct socketlist *socklist)
 998{
 999        struct sockaddr_in sin;
1000        int sockfd;
1001        long flags;
1002
1003        memset(&sin, 0, sizeof sin);
1004        sin.sin_family = AF_INET;
1005        sin.sin_port = htons(listen_port);
1006
1007        if (listen_addr) {
1008                /* Well, host better be an IP address here. */
1009                if (inet_pton(AF_INET, listen_addr, &sin.sin_addr.s_addr) <= 0)
1010                        return 0;
1011        } else {
1012                sin.sin_addr.s_addr = htonl(INADDR_ANY);
1013        }
1014
1015        sockfd = socket(AF_INET, SOCK_STREAM, 0);
1016        if (sockfd < 0)
1017                return 0;
1018
1019        if (set_reuse_addr(sockfd)) {
1020                logerror("Could not set SO_REUSEADDR: %s", strerror(errno));
1021                close(sockfd);
1022                return 0;
1023        }
1024
1025        set_keep_alive(sockfd);
1026
1027        if ( bind(sockfd, (struct sockaddr *)&sin, sizeof sin) < 0 ) {
1028                logerror("Could not bind to %s: %s",
1029                         ip2str(AF_INET, (struct sockaddr *)&sin, sizeof(sin)),
1030                         strerror(errno));
1031                close(sockfd);
1032                return 0;
1033        }
1034
1035        if (listen(sockfd, 5) < 0) {
1036                logerror("Could not listen to %s: %s",
1037                         ip2str(AF_INET, (struct sockaddr *)&sin, sizeof(sin)),
1038                         strerror(errno));
1039                close(sockfd);
1040                return 0;
1041        }
1042
1043        flags = fcntl(sockfd, F_GETFD, 0);
1044        if (flags >= 0)
1045                fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
1046
1047        ALLOC_GROW(socklist->list, socklist->nr + 1, socklist->alloc);
1048        socklist->list[socklist->nr++] = sockfd;
1049        return 1;
1050}
1051
1052#endif
1053
1054static void socksetup(struct string_list *listen_addr, int listen_port, struct socketlist *socklist)
1055{
1056        if (!listen_addr->nr)
1057                setup_named_sock(NULL, listen_port, socklist);
1058        else {
1059                int i, socknum;
1060                for (i = 0; i < listen_addr->nr; i++) {
1061                        socknum = setup_named_sock(listen_addr->items[i].string,
1062                                                   listen_port, socklist);
1063
1064                        if (socknum == 0)
1065                                logerror("unable to allocate any listen sockets for host %s on port %u",
1066                                         listen_addr->items[i].string, listen_port);
1067                }
1068        }
1069}
1070
1071static int service_loop(struct socketlist *socklist)
1072{
1073        struct pollfd *pfd;
1074        int i;
1075
1076        pfd = xcalloc(socklist->nr, sizeof(struct pollfd));
1077
1078        for (i = 0; i < socklist->nr; i++) {
1079                pfd[i].fd = socklist->list[i];
1080                pfd[i].events = POLLIN;
1081        }
1082
1083        signal(SIGCHLD, child_handler);
1084
1085        for (;;) {
1086                int i;
1087
1088                check_dead_children();
1089
1090                if (poll(pfd, socklist->nr, -1) < 0) {
1091                        if (errno != EINTR) {
1092                                logerror("Poll failed, resuming: %s",
1093                                      strerror(errno));
1094                                sleep(1);
1095                        }
1096                        continue;
1097                }
1098
1099                for (i = 0; i < socklist->nr; i++) {
1100                        if (pfd[i].revents & POLLIN) {
1101                                union {
1102                                        struct sockaddr sa;
1103                                        struct sockaddr_in sai;
1104#ifndef NO_IPV6
1105                                        struct sockaddr_in6 sai6;
1106#endif
1107                                } ss;
1108                                socklen_t sslen = sizeof(ss);
1109                                int incoming = accept(pfd[i].fd, &ss.sa, &sslen);
1110                                if (incoming < 0) {
1111                                        switch (errno) {
1112                                        case EAGAIN:
1113                                        case EINTR:
1114                                        case ECONNABORTED:
1115                                                continue;
1116                                        default:
1117                                                die_errno("accept returned");
1118                                        }
1119                                }
1120                                handle(incoming, &ss.sa, sslen);
1121                        }
1122                }
1123        }
1124}
1125
1126#ifdef NO_POSIX_GOODIES
1127
1128struct credentials;
1129
1130static void drop_privileges(struct credentials *cred)
1131{
1132        /* nothing */
1133}
1134
1135static struct credentials *prepare_credentials(const char *user_name,
1136    const char *group_name)
1137{
1138        die("--user not supported on this platform");
1139}
1140
1141#else
1142
1143struct credentials {
1144        struct passwd *pass;
1145        gid_t gid;
1146};
1147
1148static void drop_privileges(struct credentials *cred)
1149{
1150        if (cred && (initgroups(cred->pass->pw_name, cred->gid) ||
1151            setgid (cred->gid) || setuid(cred->pass->pw_uid)))
1152                die("cannot drop privileges");
1153}
1154
1155static struct credentials *prepare_credentials(const char *user_name,
1156    const char *group_name)
1157{
1158        static struct credentials c;
1159
1160        c.pass = getpwnam(user_name);
1161        if (!c.pass)
1162                die("user not found - %s", user_name);
1163
1164        if (!group_name)
1165                c.gid = c.pass->pw_gid;
1166        else {
1167                struct group *group = getgrnam(group_name);
1168                if (!group)
1169                        die("group not found - %s", group_name);
1170
1171                c.gid = group->gr_gid;
1172        }
1173
1174        return &c;
1175}
1176#endif
1177
1178static int serve(struct string_list *listen_addr, int listen_port,
1179    struct credentials *cred)
1180{
1181        struct socketlist socklist = { NULL, 0, 0 };
1182
1183        socksetup(listen_addr, listen_port, &socklist);
1184        if (socklist.nr == 0)
1185                die("unable to allocate any listen sockets on port %u",
1186                    listen_port);
1187
1188        drop_privileges(cred);
1189
1190        loginfo("Ready to rumble");
1191
1192        return service_loop(&socklist);
1193}
1194
1195int main(int argc, char **argv)
1196{
1197        int listen_port = 0;
1198        struct string_list listen_addr = STRING_LIST_INIT_NODUP;
1199        int serve_mode = 0, inetd_mode = 0;
1200        const char *pid_file = NULL, *user_name = NULL, *group_name = NULL;
1201        int detach = 0;
1202        struct credentials *cred = NULL;
1203        int i;
1204
1205        git_setup_gettext();
1206
1207        git_extract_argv0_path(argv[0]);
1208
1209        for (i = 1; i < argc; i++) {
1210                char *arg = argv[i];
1211                const char *v;
1212
1213                if (skip_prefix(arg, "--listen=", &v)) {
1214                        string_list_append(&listen_addr, xstrdup_tolower(v));
1215                        continue;
1216                }
1217                if (skip_prefix(arg, "--port=", &v)) {
1218                        char *end;
1219                        unsigned long n;
1220                        n = strtoul(v, &end, 0);
1221                        if (*v && !*end) {
1222                                listen_port = n;
1223                                continue;
1224                        }
1225                }
1226                if (!strcmp(arg, "--serve")) {
1227                        serve_mode = 1;
1228                        continue;
1229                }
1230                if (!strcmp(arg, "--inetd")) {
1231                        inetd_mode = 1;
1232                        log_syslog = 1;
1233                        continue;
1234                }
1235                if (!strcmp(arg, "--verbose")) {
1236                        verbose = 1;
1237                        continue;
1238                }
1239                if (!strcmp(arg, "--syslog")) {
1240                        log_syslog = 1;
1241                        continue;
1242                }
1243                if (!strcmp(arg, "--export-all")) {
1244                        export_all_trees = 1;
1245                        continue;
1246                }
1247                if (skip_prefix(arg, "--access-hook=", &v)) {
1248                        access_hook = v;
1249                        continue;
1250                }
1251                if (skip_prefix(arg, "--timeout=", &v)) {
1252                        timeout = atoi(v);
1253                        continue;
1254                }
1255                if (skip_prefix(arg, "--init-timeout=", &v)) {
1256                        init_timeout = atoi(v);
1257                        continue;
1258                }
1259                if (skip_prefix(arg, "--max-connections=", &v)) {
1260                        max_connections = atoi(v);
1261                        if (max_connections < 0)
1262                                max_connections = 0;            /* unlimited */
1263                        continue;
1264                }
1265                if (!strcmp(arg, "--strict-paths")) {
1266                        strict_paths = 1;
1267                        continue;
1268                }
1269                if (skip_prefix(arg, "--base-path=", &v)) {
1270                        base_path = v;
1271                        continue;
1272                }
1273                if (!strcmp(arg, "--base-path-relaxed")) {
1274                        base_path_relaxed = 1;
1275                        continue;
1276                }
1277                if (skip_prefix(arg, "--interpolated-path=", &v)) {
1278                        interpolated_path = v;
1279                        continue;
1280                }
1281                if (!strcmp(arg, "--reuseaddr")) {
1282                        reuseaddr = 1;
1283                        continue;
1284                }
1285                if (!strcmp(arg, "--user-path")) {
1286                        user_path = "";
1287                        continue;
1288                }
1289                if (skip_prefix(arg, "--user-path=", &v)) {
1290                        user_path = v;
1291                        continue;
1292                }
1293                if (skip_prefix(arg, "--pid-file=", &v)) {
1294                        pid_file = v;
1295                        continue;
1296                }
1297                if (!strcmp(arg, "--detach")) {
1298                        detach = 1;
1299                        log_syslog = 1;
1300                        continue;
1301                }
1302                if (skip_prefix(arg, "--user=", &v)) {
1303                        user_name = v;
1304                        continue;
1305                }
1306                if (skip_prefix(arg, "--group=", &v)) {
1307                        group_name = v;
1308                        continue;
1309                }
1310                if (skip_prefix(arg, "--enable=", &v)) {
1311                        enable_service(v, 1);
1312                        continue;
1313                }
1314                if (skip_prefix(arg, "--disable=", &v)) {
1315                        enable_service(v, 0);
1316                        continue;
1317                }
1318                if (skip_prefix(arg, "--allow-override=", &v)) {
1319                        make_service_overridable(v, 1);
1320                        continue;
1321                }
1322                if (skip_prefix(arg, "--forbid-override=", &v)) {
1323                        make_service_overridable(v, 0);
1324                        continue;
1325                }
1326                if (!strcmp(arg, "--informative-errors")) {
1327                        informative_errors = 1;
1328                        continue;
1329                }
1330                if (!strcmp(arg, "--no-informative-errors")) {
1331                        informative_errors = 0;
1332                        continue;
1333                }
1334                if (!strcmp(arg, "--")) {
1335                        ok_paths = &argv[i+1];
1336                        break;
1337                } else if (arg[0] != '-') {
1338                        ok_paths = &argv[i];
1339                        break;
1340                }
1341
1342                usage(daemon_usage);
1343        }
1344
1345        if (log_syslog) {
1346                openlog("git-daemon", LOG_PID, LOG_DAEMON);
1347                set_die_routine(daemon_die);
1348        } else
1349                /* avoid splitting a message in the middle */
1350                setvbuf(stderr, NULL, _IOFBF, 4096);
1351
1352        if (inetd_mode && (detach || group_name || user_name))
1353                die("--detach, --user and --group are incompatible with --inetd");
1354
1355        if (inetd_mode && (listen_port || (listen_addr.nr > 0)))
1356                die("--listen= and --port= are incompatible with --inetd");
1357        else if (listen_port == 0)
1358                listen_port = DEFAULT_GIT_PORT;
1359
1360        if (group_name && !user_name)
1361                die("--group supplied without --user");
1362
1363        if (user_name)
1364                cred = prepare_credentials(user_name, group_name);
1365
1366        if (strict_paths && (!ok_paths || !*ok_paths))
1367                die("option --strict-paths requires a whitelist");
1368
1369        if (base_path && !is_directory(base_path))
1370                die("base-path '%s' does not exist or is not a directory",
1371                    base_path);
1372
1373        if (inetd_mode) {
1374                if (!freopen("/dev/null", "w", stderr))
1375                        die_errno("failed to redirect stderr to /dev/null");
1376        }
1377
1378        if (inetd_mode || serve_mode)
1379                return execute();
1380
1381        if (detach) {
1382                if (daemonize())
1383                        die("--detach not supported on this platform");
1384        } else
1385                sanitize_stdfds();
1386
1387        if (pid_file)
1388                write_file(pid_file, "%"PRIuMAX, (uintmax_t) getpid());
1389
1390        /* prepare argv for serving-processes */
1391        argv_array_push(&cld_argv, argv[0]); /* git-daemon */
1392        argv_array_push(&cld_argv, "--serve");
1393        for (i = 1; i < argc; ++i)
1394                argv_array_push(&cld_argv, argv[i]);
1395
1396        return serve(&listen_addr, listen_port, cred);
1397}