| … | |
… | |
| 32 | #include <cstdlib> |
32 | #include <cstdlib> |
| 33 | #include <cstring> |
33 | #include <cstring> |
| 34 | #include <csignal> |
34 | #include <csignal> |
| 35 | |
35 | |
| 36 | #include <sys/types.h> |
36 | #include <sys/types.h> |
| 37 | #include <sys/socket.h> |
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| 38 | #include <unistd.h> |
37 | #include <unistd.h> |
| 39 | #include <fcntl.h> |
38 | #include <fcntl.h> |
| 40 | |
39 | |
| 41 | #ifdef HAVE_SYS_IOCTL_H |
40 | #ifdef HAVE_SYS_IOCTL_H |
| 42 | # include <sys/ioctl.h> |
41 | # include <sys/ioctl.h> |
| … | |
… | |
| 372 | } |
371 | } |
| 373 | |
372 | |
| 374 | return true; |
373 | return true; |
| 375 | } |
374 | } |
| 376 | |
375 | |
| 377 | ///////////////////////////////////////////////////////////////////////////// |
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| 378 | // helper/proxy support |
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| 379 | |
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| 380 | #if PTYTTY_HELPER |
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| 381 | |
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| 382 | static int sock_fd = -1, lock_fd = -1; |
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| 383 | static int helper_pid, owner_pid; |
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| 384 | |
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| 385 | struct command |
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| 386 | { |
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| 387 | enum { get, login, destroy } type; |
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| 388 | |
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| 389 | ptytty *id; |
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| 390 | |
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| 391 | bool login_shell; |
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| 392 | int cmd_pid; |
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| 393 | char hostname[512]; // arbitrary, but should be plenty |
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| 394 | }; |
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| 395 | |
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| 396 | struct ptytty_proxy : ptytty |
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| 397 | { |
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| 398 | ptytty *id; |
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| 399 | |
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| 400 | ptytty_proxy () |
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| 401 | : id(0) |
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| 402 | { |
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| 403 | } |
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| 404 | |
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| 405 | ~ptytty_proxy (); |
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| 406 | |
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| 407 | bool get (); |
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| 408 | void login (int cmd_pid, bool login_shell, const char *hostname); |
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| 409 | }; |
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| 410 | |
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| 411 | #if PTYTTY_REENTRANT |
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| 412 | # define NEED_TOKEN do { char ch; read (lock_fd, &ch, 1); } while (0) |
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| 413 | # define GIVE_TOKEN do { char ch; write (lock_fd, &ch, 1); } while (0) |
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| 414 | #else |
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| 415 | # define NEED_TOKEN (void)0 |
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| 416 | # define GIVE_TOKEN (void)0 |
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| 417 | #endif |
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| 418 | |
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| 419 | bool |
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| 420 | ptytty_proxy::get () |
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| 421 | { |
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| 422 | NEED_TOKEN; |
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| 423 | |
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| 424 | command cmd; |
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| 425 | |
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| 426 | cmd.type = command::get; |
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| 427 | |
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| 428 | write (sock_fd, &cmd, sizeof (cmd)); |
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| 429 | |
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| 430 | if (read (sock_fd, &id, sizeof (id)) != sizeof (id)) |
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| 431 | ptytty_fatal ("protocol error while creating pty using helper process, aborting.\n"); |
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| 432 | |
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| 433 | if (!id) |
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| 434 | { |
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| 435 | GIVE_TOKEN; |
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| 436 | return false; |
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| 437 | } |
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| 438 | |
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| 439 | if ((pty = recv_fd (sock_fd)) < 0 |
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| 440 | || (tty = recv_fd (sock_fd)) < 0) |
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| 441 | ptytty_fatal ("protocol error while reading pty/tty fds from helper process, aborting.\n"); |
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| 442 | |
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| 443 | GIVE_TOKEN; |
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| 444 | return true; |
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| 445 | } |
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| 446 | |
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| 447 | void |
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| 448 | ptytty_proxy::login (int cmd_pid, bool login_shell, const char *hostname) |
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| 449 | { |
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| 450 | NEED_TOKEN; |
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| 451 | |
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| 452 | command cmd; |
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| 453 | |
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| 454 | cmd.type = command::login; |
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| 455 | cmd.id = id; |
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| 456 | cmd.cmd_pid = cmd_pid; |
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| 457 | cmd.login_shell = login_shell; |
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| 458 | strncpy (cmd.hostname, hostname, sizeof (cmd.hostname)); |
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| 459 | |
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| 460 | write (sock_fd, &cmd, sizeof (cmd)); |
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| 461 | |
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| 462 | GIVE_TOKEN; |
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| 463 | } |
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| 464 | |
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| 465 | ptytty_proxy::~ptytty_proxy () |
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| 466 | { |
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| 467 | if (id) |
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| 468 | { |
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| 469 | NEED_TOKEN; |
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| 470 | |
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| 471 | command cmd; |
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| 472 | |
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| 473 | cmd.type = command::destroy; |
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| 474 | cmd.id = id; |
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| 475 | |
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| 476 | write (sock_fd, &cmd, sizeof (cmd)); |
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| 477 | |
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| 478 | GIVE_TOKEN; |
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| 479 | } |
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| 480 | } |
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| 481 | |
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| 482 | static |
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| 483 | void serve () |
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| 484 | { |
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| 485 | command cmd; |
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| 486 | vector<ptytty *> ptys; |
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| 487 | |
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| 488 | for (;;) |
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| 489 | { |
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| 490 | GIVE_TOKEN; |
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| 491 | |
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| 492 | if (read (sock_fd, &cmd, sizeof (command)) != sizeof (command)) |
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| 493 | break; |
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| 494 | |
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| 495 | if (cmd.type == command::get) |
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| 496 | { |
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| 497 | // -> id ptyfd ttyfd |
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| 498 | cmd.id = new ptytty_unix; |
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| 499 | |
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| 500 | if (cmd.id->get ()) |
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| 501 | { |
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| 502 | write (sock_fd, &cmd.id, sizeof (cmd.id)); |
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| 503 | ptys.push_back (cmd.id); |
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| 504 | |
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| 505 | ptytty::send_fd (sock_fd, cmd.id->pty); |
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| 506 | ptytty::send_fd (sock_fd, cmd.id->tty); |
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| 507 | } |
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| 508 | else |
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| 509 | { |
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| 510 | delete cmd.id; |
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| 511 | cmd.id = 0; |
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| 512 | write (sock_fd, &cmd.id, sizeof (cmd.id)); |
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| 513 | } |
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| 514 | } |
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| 515 | else if (cmd.type == command::login) |
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| 516 | { |
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| 517 | #if UTMP_SUPPORT |
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| 518 | if (find (ptys.begin (), ptys.end (), cmd.id) != ptys.end ()) |
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| 519 | { |
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| 520 | cmd.hostname[sizeof (cmd.hostname) - 1] = 0; |
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| 521 | cmd.id->login (cmd.cmd_pid, cmd.login_shell, cmd.hostname); |
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| 522 | } |
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| 523 | #endif |
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| 524 | } |
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| 525 | else if (cmd.type == command::destroy) |
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| 526 | { |
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| 527 | vector<ptytty *>::iterator pty = find (ptys.begin (), ptys.end (), cmd.id); |
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| 528 | |
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| 529 | if (pty != ptys.end ()) |
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| 530 | { |
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| 531 | delete *pty; |
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| 532 | ptys.erase (pty); |
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| 533 | } |
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| 534 | } |
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| 535 | else |
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| 536 | break; |
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| 537 | |
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| 538 | NEED_TOKEN; |
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| 539 | } |
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| 540 | |
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| 541 | // destroy all ptys |
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| 542 | for (vector<ptytty *>::iterator i = ptys.end (); i-- > ptys.begin (); ) |
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| 543 | delete *i; |
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| 544 | } |
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| 545 | |
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| 546 | void |
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| 547 | ptytty::use_helper () |
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| 548 | { |
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| 549 | #ifndef PTYTTY_NO_PID_CHECK |
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| 550 | int pid = getpid (); |
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| 551 | #endif |
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| 552 | |
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| 553 | if (sock_fd >= 0 |
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| 554 | #ifndef PTYTTY_NO_PID_CHECK |
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| 555 | && pid == owner_pid |
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| 556 | #endif |
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| 557 | ) |
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| 558 | return; |
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| 559 | |
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| 560 | #ifndef PTYTTY_NO_PID_CHECK |
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| 561 | owner_pid = pid; |
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| 562 | #endif |
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| 563 | |
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| 564 | int sv[2]; |
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| 565 | |
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| 566 | if (socketpair (AF_UNIX, SOCK_STREAM, 0, sv)) |
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| 567 | ptytty_fatal ("could not create socket to communicate with pty/sessiondb helper, aborting.\n"); |
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| 568 | |
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| 569 | #ifdef PTYTTY_REENTRANT |
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| 570 | int lv[2]; |
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| 571 | |
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| 572 | if (socketpair (AF_UNIX, SOCK_STREAM, 0, lv)) |
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| 573 | ptytty_fatal ("could not create socket to communicate with pty/sessiondb helper, aborting.\n"); |
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| 574 | #endif |
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| 575 | |
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| 576 | helper_pid = fork (); |
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| 577 | |
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| 578 | if (helper_pid < 0) |
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| 579 | ptytty_fatal ("could not create pty/sessiondb helper process, aborting.\n"); |
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| 580 | |
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| 581 | if (helper_pid) |
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| 582 | { |
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| 583 | // client, process |
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| 584 | sock_fd = sv[0]; |
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| 585 | close (sv[1]); |
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| 586 | fcntl (sock_fd, F_SETFD, FD_CLOEXEC); |
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| 587 | #ifdef PTYTTY_REENTRANT |
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| 588 | lock_fd = lv[0]; |
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| 589 | close (lv[1]); |
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| 590 | fcntl (lock_fd, F_SETFD, FD_CLOEXEC); |
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| 591 | #endif |
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| 592 | } |
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| 593 | else |
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| 594 | { |
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| 595 | // server, pty-helper |
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| 596 | sock_fd = sv[1]; |
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| 597 | #ifdef PTYTTY_REENTRANT |
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| 598 | lock_fd = lv[1]; |
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| 599 | #endif |
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| 600 | |
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| 601 | chdir ("/"); |
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| 602 | |
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| 603 | signal (SIGHUP, SIG_IGN); |
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| 604 | signal (SIGTERM, SIG_IGN); |
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| 605 | signal (SIGINT, SIG_IGN); |
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| 606 | signal (SIGPIPE, SIG_IGN); |
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| 607 | |
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| 608 | for (int fd = 0; fd < 1023; fd++) |
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| 609 | if (fd != sock_fd && fd != lock_fd) |
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| 610 | close (fd); |
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| 611 | |
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| 612 | serve (); |
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| 613 | _exit (EXIT_SUCCESS); |
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| 614 | } |
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| 615 | } |
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| 616 | |
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| 617 | #endif |
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| 618 | |
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| 619 | ptytty * |
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| 620 | ptytty::create () |
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| 621 | { |
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| 622 | #if PTYTTY_HELPER |
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| 623 | if (helper_pid |
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| 624 | # ifndef PTYTTY_NO_PID_CHECK |
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| 625 | && getpid () == owner_pid |
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| 626 | # endif |
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| 627 | ) |
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| 628 | // use helper process |
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| 629 | return new ptytty_proxy; |
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| 630 | else |
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| 631 | #endif |
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| 632 | return new ptytty_unix; |
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| 633 | } |
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| 634 | |
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| 635 | void |
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| 636 | ptytty::init () |
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| 637 | { |
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| 638 | uid_t uid = getuid (); |
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| 639 | gid_t gid = getgid (); |
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| 640 | |
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| 641 | // before doing anything else, check for setuid/setgid operation, |
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| 642 | // start the helper process and drop privileges |
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| 643 | if (uid != geteuid () |
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| 644 | || gid != getegid ()) |
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| 645 | { |
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| 646 | #if PTYTTY_HELPER |
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| 647 | use_helper (); |
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| 648 | #else |
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| 649 | ptytty_warn ("running setuid/setgid without pty helper compiled in, continuing unprivileged.\n"); |
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| 650 | #endif |
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| 651 | |
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| 652 | drop_privileges (); |
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| 653 | } |
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| 654 | } |
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| 655 | |
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| 656 | void |
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| 657 | ptytty::drop_privileges () |
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| 658 | { |
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| 659 | uid_t uid = getuid (); |
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| 660 | gid_t gid = getgid (); |
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| 661 | |
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| 662 | // drop privileges |
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| 663 | #if HAVE_SETRESUID |
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| 664 | setresgid (gid, gid, gid); |
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| 665 | setresuid (uid, uid, uid); |
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| 666 | #elif HAVE_SETREUID |
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| 667 | setregid (gid, gid); |
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| 668 | setreuid (uid, uid); |
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| 669 | #elif HAVE_SETUID |
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| 670 | setgid (gid); |
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| 671 | setuid (uid); |
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| 672 | #endif |
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| 673 | |
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| 674 | if (uid != geteuid () |
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| 675 | || gid != getegid ()) |
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| 676 | ptytty_fatal ("unable to drop privileges, aborting.\n"); |
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| 677 | } |
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| 678 | |
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| 679 | ///////////////////////////////////////////////////////////////////////////// |
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| 680 | // C API |
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| 681 | |
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| 682 | #ifndef PTYTTY_NO_C_API |
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| 683 | |
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| 684 | typedef void *PTYTTY; |
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| 685 | |
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| 686 | #define DEFINE_METHOD(retval, name, args1, args2) \ |
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| 687 | extern "C" retval ptytty_ ## name args1 \ |
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| 688 | { return ((struct ptytty *)ptytty)->name args2; } |
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| 689 | |
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| 690 | DEFINE_METHOD(int,pty,(PTYTTY ptytty),) |
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| 691 | DEFINE_METHOD(int,tty,(PTYTTY ptytty),) |
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| 692 | DEFINE_METHOD(int,get,(PTYTTY ptytty),()) |
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| 693 | DEFINE_METHOD(void,login,(PTYTTY ptytty, int cmd_pid, bool login_shell, const char *hostname),(cmd_pid,login_shell,hostname)) |
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| 694 | |
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| 695 | DEFINE_METHOD(void,close_tty,(PTYTTY ptytty),()) |
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| 696 | DEFINE_METHOD(int,make_controlling_tty,(PTYTTY ptytty),()) |
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| 697 | DEFINE_METHOD(void,set_utf8_mode,(PTYTTY ptytty, int on),(on)) |
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| 698 | |
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| 699 | #define DEFINE_STATIC(retval, name, args) \ |
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| 700 | extern "C" retval ptytty_ ## name args \ |
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| 701 | { return ptytty::name args; } |
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| 702 | |
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| 703 | DEFINE_STATIC(void,drop_privileges,()) |
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| 704 | DEFINE_STATIC(void,use_helper,()) |
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| 705 | DEFINE_STATIC(void,init,()) |
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| 706 | |
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| 707 | DEFINE_STATIC(PTYTTY ,create,()) |
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| 708 | |
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| 709 | void ptytty_delete (PTYTTY ptytty) |
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| 710 | { |
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| 711 | delete (struct ptytty *)ptytty; |
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| 712 | } |
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| 713 | |
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| 714 | // send_fd, recv_fd not exposed |
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| 715 | |
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| 716 | #endif |
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