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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> |
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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 | bool |
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412 | ptytty_proxy::get () |
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413 | { |
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414 | command cmd; |
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415 | |
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416 | cmd.type = command::get; |
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417 | |
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418 | write (sock_fd, &cmd, sizeof (cmd)); |
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419 | |
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420 | if (read (sock_fd, &id, sizeof (id)) != sizeof (id)) |
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421 | ptytty_fatal ("protocol error while creating pty using helper process, aborting.\n"); |
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422 | |
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423 | if (!id) |
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424 | return false; |
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425 | |
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426 | if ((pty = recv_fd (sock_fd)) < 0 |
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427 | || (tty = recv_fd (sock_fd)) < 0) |
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428 | ptytty_fatal ("protocol error while reading pty/tty fds from helper process, aborting.\n"); |
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429 | |
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430 | return true; |
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431 | } |
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432 | |
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433 | void |
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434 | ptytty_proxy::login (int cmd_pid, bool login_shell, const char *hostname) |
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435 | { |
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436 | command cmd; |
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437 | |
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438 | cmd.type = command::login; |
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439 | cmd.id = id; |
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440 | cmd.cmd_pid = cmd_pid; |
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441 | cmd.login_shell = login_shell; |
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442 | strncpy (cmd.hostname, hostname, sizeof (cmd.hostname)); |
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443 | |
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444 | write (sock_fd, &cmd, sizeof (cmd)); |
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445 | } |
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446 | |
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447 | ptytty_proxy::~ptytty_proxy () |
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448 | { |
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449 | if (id) |
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450 | { |
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451 | command cmd; |
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452 | |
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453 | cmd.type = command::destroy; |
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454 | cmd.id = id; |
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455 | |
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456 | write (sock_fd, &cmd, sizeof (cmd)); |
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457 | } |
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458 | } |
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459 | |
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460 | static |
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461 | void serve () |
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462 | { |
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463 | command cmd; |
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464 | vector<ptytty *> ptys; |
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465 | |
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466 | while (read (sock_fd, &cmd, sizeof (command)) == sizeof (command)) |
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467 | { |
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468 | if (cmd.type == command::get) |
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469 | { |
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470 | // -> id ptyfd ttyfd |
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471 | cmd.id = new ptytty_unix; |
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472 | |
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473 | if (cmd.id->get ()) |
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474 | { |
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475 | write (sock_fd, &cmd.id, sizeof (cmd.id)); |
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476 | ptys.push_back (cmd.id); |
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477 | |
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478 | ptytty::send_fd (sock_fd, cmd.id->pty); |
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479 | ptytty::send_fd (sock_fd, cmd.id->tty); |
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480 | } |
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481 | else |
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482 | { |
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483 | delete cmd.id; |
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484 | cmd.id = 0; |
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485 | write (sock_fd, &cmd.id, sizeof (cmd.id)); |
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486 | } |
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487 | } |
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488 | else if (cmd.type == command::login) |
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489 | { |
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490 | #if UTMP_SUPPORT |
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491 | if (find (ptys.begin (), ptys.end (), cmd.id) != ptys.end ()) |
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492 | { |
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493 | cmd.hostname[sizeof (cmd.hostname) - 1] = 0; |
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494 | cmd.id->login (cmd.cmd_pid, cmd.login_shell, cmd.hostname); |
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495 | } |
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496 | #endif |
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497 | } |
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498 | else if (cmd.type == command::destroy) |
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499 | { |
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500 | vector<ptytty *>::iterator pty = find (ptys.begin (), ptys.end (), cmd.id); |
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501 | |
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502 | if (pty != ptys.end ()) |
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503 | { |
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504 | delete *pty; |
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505 | ptys.erase (pty); |
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506 | } |
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507 | } |
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508 | else |
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509 | break; |
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510 | } |
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511 | |
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512 | // destroy all ptys |
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513 | for (vector<ptytty *>::iterator i = ptys.end (); i-- > ptys.begin (); ) |
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514 | delete *i; |
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515 | } |
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516 | |
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517 | void |
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518 | ptytty::use_helper () |
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519 | { |
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520 | int pid = getpid (); |
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521 | |
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522 | if (sock_fd >= 0 && pid == owner_pid) |
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523 | return; |
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524 | |
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525 | owner_pid = pid; |
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526 | |
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527 | int sv[2]; |
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528 | |
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529 | if (socketpair (AF_UNIX, SOCK_STREAM, 0, sv)) |
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530 | ptytty_fatal ("could not create socket to communicate with pty/sessiondb helper, aborting.\n"); |
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531 | |
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532 | #ifdef PTYTTY_REENTRANT |
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533 | int lv[2]; |
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534 | |
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535 | if (socketpair (AF_UNIX, SOCK_STREAM, 0, lv)) |
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536 | ptytty_fatal ("could not create socket to communicate with pty/sessiondb helper, aborting.\n"); |
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537 | #endif |
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538 | |
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539 | helper_pid = fork (); |
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540 | |
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541 | if (helper_pid < 0) |
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542 | ptytty_fatal ("could not create pty/sessiondb helper process, aborting.\n"); |
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543 | |
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544 | if (helper_pid) |
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545 | { |
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546 | // client, process |
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547 | sock_fd = sv[0]; |
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548 | close (sv[1]); |
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549 | fcntl (sock_fd, F_SETFD, FD_CLOEXEC); |
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550 | #ifdef PTYTTY_REENTRANT |
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551 | lock_fd = lv[0]; |
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552 | close (lv[1]); |
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553 | fcntl (lock_fd, F_SETFD, FD_CLOEXEC); |
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554 | #endif |
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555 | } |
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556 | else |
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557 | { |
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558 | // server, pty-helper |
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559 | sock_fd = sv[1]; |
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560 | #ifdef PTYTTY_REENTRANT |
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561 | lock_fd = lv[1]; |
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562 | #endif |
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563 | |
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564 | chdir ("/"); |
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565 | |
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566 | signal (SIGHUP, SIG_IGN); |
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567 | signal (SIGTERM, SIG_IGN); |
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568 | signal (SIGINT, SIG_IGN); |
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569 | signal (SIGPIPE, SIG_IGN); |
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570 | |
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571 | for (int fd = 0; fd < 1023; fd++) |
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572 | if (fd != sock_fd && fd != lock_fd) |
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573 | close (fd); |
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574 | |
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575 | serve (); |
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576 | _exit (EXIT_SUCCESS); |
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577 | } |
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578 | } |
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579 | |
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580 | #endif |
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581 | |
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582 | ptytty * |
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583 | ptytty::create () |
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584 | { |
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585 | #if PTYTTY_HELPER |
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586 | if (helper_pid && getpid () == owner_pid) |
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587 | // use helper process |
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588 | return new ptytty_proxy; |
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589 | else |
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590 | #endif |
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591 | return new ptytty_unix; |
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592 | } |
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593 | |
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594 | void |
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595 | ptytty::init () |
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596 | { |
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597 | uid_t uid = getuid (); |
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598 | gid_t gid = getgid (); |
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599 | |
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600 | // before doing anything else, check for setuid/setgid operation, |
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601 | // start the helper process and drop privileges |
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602 | if (uid != geteuid () |
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603 | || gid != getegid ()) |
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604 | { |
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605 | #if PTYTTY_HELPER |
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606 | use_helper (); |
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607 | #else |
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608 | ptytty_warn ("running setuid/setgid without pty helper compiled in, continuing unprivileged.\n"); |
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609 | #endif |
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610 | |
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611 | drop_privileges (); |
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612 | } |
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613 | } |
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614 | |
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615 | void |
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616 | ptytty::drop_privileges () |
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617 | { |
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618 | uid_t uid = getuid (); |
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619 | gid_t gid = getgid (); |
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620 | |
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621 | // drop privileges |
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622 | #if HAVE_SETRESUID |
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623 | setresgid (gid, gid, gid); |
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624 | setresuid (uid, uid, uid); |
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625 | #elif HAVE_SETREUID |
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626 | setregid (gid, gid); |
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627 | setreuid (uid, uid); |
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628 | #elif HAVE_SETUID |
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629 | setgid (gid); |
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630 | setuid (uid); |
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631 | #endif |
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632 | |
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633 | if (uid != geteuid () |
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634 | || gid != getegid ()) |
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635 | ptytty_fatal ("unable to drop privileges, aborting.\n"); |
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636 | } |
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637 | |
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638 | ///////////////////////////////////////////////////////////////////////////// |
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639 | // C API |
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640 | |
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641 | #ifndef NO_C_API |
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642 | |
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643 | #define DEFINE_METHOD(retval, name, args1, args2) \ |
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644 | extern "C" retval ptytty_ ## name args1 \ |
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645 | { return ((struct ptytty *)ptytty)->name args2; } |
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646 | |
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647 | DEFINE_METHOD(int,pty,(void *ptytty),) |
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648 | DEFINE_METHOD(int,tty,(void *ptytty),) |
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649 | DEFINE_METHOD(int,get,(void *ptytty),()) |
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650 | DEFINE_METHOD(void,login,(void *ptytty, int cmd_pid, bool login_shell, const char *hostname),(cmd_pid,login_shell,hostname)) |
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651 | |
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652 | DEFINE_METHOD(void,close_tty,(void *ptytty),()) |
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653 | DEFINE_METHOD(int,make_controlling_tty,(void *ptytty),()) |
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654 | DEFINE_METHOD(void,set_utf8_mode,(void *ptytty, int on),(on)) |
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655 | |
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656 | #define DEFINE_STATIC(retval, name, args) \ |
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657 | extern "C" retval ptytty_ ## name args \ |
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658 | { return ptytty::name args; } |
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659 | |
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660 | DEFINE_STATIC(void,drop_privileges,()) |
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661 | DEFINE_STATIC(void,use_helper,()) |
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662 | DEFINE_STATIC(void,init,()) |
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663 | |
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664 | DEFINE_STATIC(void *,create,()) |
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665 | |
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666 | void ptytty_delete (void *ptytty) |
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667 | { |
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668 | delete (struct ptytty *)ptytty; |
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669 | } |
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670 | |
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671 | // send_fd, recv_fd not exposed |
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672 | |
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673 | #endif |
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