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6 | *----------------------------------------------------------------------* |
6 | *----------------------------------------------------------------------* |
7 | * |
7 | * |
8 | * All portions of code are copyright by their respective author/s. |
8 | * All portions of code are copyright by their respective author/s. |
9 | * Copyright (c) 1999-2001 Geoff Wing <gcw@pobox.com> |
9 | * Copyright (c) 1999-2001 Geoff Wing <gcw@pobox.com> |
10 | * Copyright (c) 2004-2006 Marc Lehmann <pcg@goof.com> |
10 | * Copyright (c) 2004-2006 Marc Lehmann <pcg@goof.com> |
11 | * Copyright (c) 2006 Emanuele Giaquinta <e.giaquinta@glauco.it> |
11 | * Copyright (c) 2006 Emanuele Giaquinta <e.giaquinta@glauco.it> |
12 | * |
12 | * |
13 | * This program is free software; you can redistribute it and/or modify |
13 | * This program is free software; you can redistribute it and/or modify |
14 | * it under the terms of the GNU General Public License as published by |
14 | * it under the terms of the GNU General Public License as published by |
15 | * the Free Software Foundation; either version 2 of the License, or |
15 | * the Free Software Foundation; either version 2 of the License, or |
16 | * (at your option) any later version. |
16 | * (at your option) any later version. |
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29 | |
29 | |
30 | #include "ptytty.h" |
30 | #include "ptytty.h" |
31 | |
31 | |
32 | #include <cstdlib> |
32 | #include <cstdlib> |
33 | #include <cstring> |
33 | #include <cstring> |
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34 | #include <csignal> |
34 | |
35 | |
35 | #include <sys/types.h> |
36 | #include <sys/types.h> |
36 | #include <sys/socket.h> |
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37 | #include <unistd.h> |
37 | #include <unistd.h> |
38 | #include <fcntl.h> |
38 | #include <fcntl.h> |
39 | |
39 | |
40 | #ifdef HAVE_SYS_IOCTL_H |
40 | #ifdef HAVE_SYS_IOCTL_H |
41 | # include <sys/ioctl.h> |
41 | # include <sys/ioctl.h> |
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371 | } |
371 | } |
372 | |
372 | |
373 | return true; |
373 | return true; |
374 | } |
374 | } |
375 | |
375 | |
376 | #if PTYTTY_HELPER |
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377 | |
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378 | static int sock_fd = -1; |
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379 | static int helper_pid, owner_pid; |
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380 | |
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381 | struct command |
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382 | { |
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383 | enum { get, login, destroy } type; |
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384 | |
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385 | ptytty *id; |
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386 | |
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387 | bool login_shell; |
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388 | int cmd_pid; |
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389 | char hostname[512]; // arbitrary, but should be plenty |
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390 | }; |
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391 | |
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392 | struct ptytty_proxy : ptytty |
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393 | { |
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394 | ptytty *id; |
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395 | |
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396 | ptytty_proxy () |
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397 | : id(0) |
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398 | { |
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399 | } |
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400 | |
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401 | ~ptytty_proxy (); |
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402 | |
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403 | bool get (); |
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404 | void login (int cmd_pid, bool login_shell, const char *hostname); |
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405 | }; |
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406 | |
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407 | bool |
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408 | ptytty_proxy::get () |
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409 | { |
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410 | command cmd; |
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411 | |
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412 | cmd.type = command::get; |
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413 | |
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414 | write (sock_fd, &cmd, sizeof (cmd)); |
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415 | |
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416 | if (read (sock_fd, &id, sizeof (id)) != sizeof (id)) |
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417 | ptytty_fatal ("protocol error while creating pty using helper process, aborting.\n"); |
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418 | |
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419 | if (!id) |
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420 | return false; |
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421 | |
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422 | if ((pty = recv_fd (sock_fd)) < 0 |
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423 | || (tty = recv_fd (sock_fd)) < 0) |
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424 | ptytty_fatal ("protocol error while reading pty/tty fds from helper process, aborting.\n"); |
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425 | |
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426 | return true; |
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427 | } |
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428 | |
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429 | void |
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430 | ptytty_proxy::login (int cmd_pid, bool login_shell, const char *hostname) |
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431 | { |
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432 | command cmd; |
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433 | |
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434 | cmd.type = command::login; |
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435 | cmd.id = id; |
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436 | cmd.cmd_pid = cmd_pid; |
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437 | cmd.login_shell = login_shell; |
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438 | strncpy (cmd.hostname, hostname, sizeof (cmd.hostname)); |
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439 | |
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440 | write (sock_fd, &cmd, sizeof (cmd)); |
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441 | } |
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442 | |
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443 | ptytty_proxy::~ptytty_proxy () |
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444 | { |
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445 | if (id) |
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446 | { |
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447 | command cmd; |
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448 | |
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449 | cmd.type = command::destroy; |
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450 | cmd.id = id; |
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451 | |
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452 | write (sock_fd, &cmd, sizeof (cmd)); |
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453 | } |
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454 | } |
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455 | |
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456 | static |
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457 | void serve () |
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458 | { |
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459 | command cmd; |
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460 | vector<ptytty *> ptys; |
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461 | |
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462 | while (read (sock_fd, &cmd, sizeof (command)) == sizeof (command)) |
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463 | { |
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464 | if (cmd.type == command::get) |
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465 | { |
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466 | // -> id ptyfd ttyfd |
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467 | cmd.id = new ptytty_unix; |
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468 | |
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469 | if (cmd.id->get ()) |
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470 | { |
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471 | write (sock_fd, &cmd.id, sizeof (cmd.id)); |
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472 | ptys.push_back (cmd.id); |
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473 | |
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474 | ptytty::send_fd (sock_fd, cmd.id->pty); |
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475 | ptytty::send_fd (sock_fd, cmd.id->tty); |
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476 | } |
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477 | else |
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478 | { |
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479 | delete cmd.id; |
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480 | cmd.id = 0; |
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481 | write (sock_fd, &cmd.id, sizeof (cmd.id)); |
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482 | } |
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483 | } |
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484 | else if (cmd.type == command::login) |
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485 | { |
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486 | #if UTMP_SUPPORT |
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487 | if (find (ptys.begin (), ptys.end (), cmd.id)) |
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488 | { |
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489 | cmd.hostname[sizeof (cmd.hostname) - 1] = 0; |
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490 | cmd.id->login (cmd.cmd_pid, cmd.login_shell, cmd.hostname); |
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491 | } |
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492 | #endif |
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493 | } |
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494 | else if (cmd.type == command::destroy) |
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495 | { |
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496 | vector<ptytty *>::iterator pty = find (ptys.begin (), ptys.end (), cmd.id); |
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497 | |
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498 | if (pty != ptys.end ()) |
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499 | { |
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500 | delete *pty; |
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501 | ptys.erase (pty); |
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502 | } |
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503 | } |
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504 | else |
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505 | break; |
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506 | } |
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507 | |
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508 | // destroy all ptys |
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509 | for (vector<ptytty *>::iterator i = ptys.end (); i-- > ptys.begin (); ) |
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510 | delete *i; |
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511 | } |
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512 | |
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513 | void |
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514 | ptytty::use_helper () |
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515 | { |
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516 | int pid = getpid (); |
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517 | |
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518 | if (sock_fd >= 0 && pid == owner_pid) |
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519 | return; |
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520 | |
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521 | owner_pid = pid; |
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522 | |
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523 | int sv[2]; |
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524 | |
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525 | if (socketpair (AF_UNIX, SOCK_STREAM, 0, sv)) |
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526 | ptytty_fatal ("could not create socket to communicate with pty/sessiondb helper, aborting.\n"); |
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527 | |
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528 | helper_pid = fork (); |
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529 | |
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530 | if (helper_pid < 0) |
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531 | ptytty_fatal ("could not create pty/sessiondb helper process, aborting.\n"); |
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532 | |
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533 | if (helper_pid) |
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534 | { |
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535 | // client, process |
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536 | sock_fd = sv[0]; |
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537 | close (sv[1]); |
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538 | fcntl (sock_fd, F_SETFD, FD_CLOEXEC); |
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539 | } |
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540 | else |
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541 | { |
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542 | // server, pty-helper |
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543 | sock_fd = sv[1]; |
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544 | |
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545 | chdir ("/"); |
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546 | |
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547 | for (int fd = 0; fd < 1023; fd++) |
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548 | if (fd != sock_fd) |
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549 | close (fd); |
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550 | |
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551 | serve (); |
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552 | _exit (EXIT_SUCCESS); |
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553 | } |
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554 | } |
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555 | |
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556 | #endif |
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557 | |
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558 | ptytty * |
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559 | ptytty::create () |
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560 | { |
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561 | #if PTYTTY_HELPER |
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562 | if (helper_pid && getpid () == owner_pid) |
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563 | // use helper process |
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564 | return new ptytty_proxy; |
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565 | else |
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566 | #endif |
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567 | return new ptytty_unix; |
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568 | } |
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569 | |
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570 | void |
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571 | ptytty::init () |
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572 | { |
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573 | uid_t uid = getuid (); |
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574 | gid_t gid = getgid (); |
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575 | |
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576 | // before doing anything else, check for setuid/setgid operation, |
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577 | // start the helper process and drop privileges |
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578 | if (uid != geteuid () |
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579 | || gid != getegid ()) |
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580 | { |
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581 | #if PTYTTY_HELPER |
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582 | use_helper (); |
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583 | #else |
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584 | ptytty_warn ("running setuid/setgid without pty helper compiled in, continuing unprivileged.\n"); |
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585 | #endif |
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586 | |
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587 | drop_privileges (); |
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588 | } |
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589 | } |
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590 | |
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591 | void |
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592 | ptytty::drop_privileges () |
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593 | { |
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594 | uid_t uid = getuid (); |
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595 | gid_t gid = getgid (); |
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596 | |
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597 | // drop privileges |
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598 | #if HAVE_SETRESUID |
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599 | setresgid (gid, gid, gid); |
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600 | setresuid (uid, uid, uid); |
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601 | #elif HAVE_SETREUID |
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602 | setregid (gid, gid); |
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603 | setreuid (uid, uid); |
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604 | #elif HAVE_SETUID |
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605 | setgid (gid); |
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606 | setuid (uid); |
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607 | #endif |
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608 | |
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609 | if (uid != geteuid () |
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610 | || gid != getegid ()) |
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611 | ptytty_fatal ("unable to drop privileges, aborting.\n"); |
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612 | } |
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613 | |
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