--- rxvt-unicode/src/ptytty.C 2006/01/22 00:48:13 1.54 +++ rxvt-unicode/src/ptytty.C 2006/01/23 12:37:59 1.60 @@ -1,10 +1,14 @@ -/*--------------------------------*-C-*---------------------------------* +// This file is part of libptytty. Do not make local modifications. +// http://software.schmorp.de/pkg/libptytty + +/*----------------------------------------------------------------------* * File: ptytty.C *----------------------------------------------------------------------* * * All portions of code are copyright by their respective author/s. * Copyright (c) 1999-2001 Geoff Wing * Copyright (c) 2004-2006 Marc Lehmann + * Copyright (c) 2006 Emanuele Giaquinta * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by @@ -21,13 +25,13 @@ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. *---------------------------------------------------------------------*/ -#include "../config.h" /* NECESSARY */ +#include "../config.h" -#include "fdpass.h" #include "ptytty.h" #include #include +#include #include #include @@ -234,7 +238,7 @@ int fd = open ("/dev/tty", O_WRONLY); if (fd < 0) - return -1; /* fatal */ + return -1; /* fatal */ close (fd); @@ -370,10 +374,13 @@ return true; } +///////////////////////////////////////////////////////////////////////////// +// helper/proxy support + #if PTYTTY_HELPER -static int sock_fd; -static int pid; +static int sock_fd = -1, lock_fd = -1; +static int helper_pid, owner_pid; struct command { @@ -401,9 +408,19 @@ void login (int cmd_pid, bool login_shell, const char *hostname); }; +#if PTYTTY_REENTRANT +# define NEED_TOKEN do { char ch; read (lock_fd, &ch, 1); } while (0) +# define GIVE_TOKEN do { char ch; write (lock_fd, &ch, 1); } while (0) +#else +# define NEED_TOKEN (void)0 +# define GIVE_TOKEN (void)0 +#endif + bool ptytty_proxy::get () { + NEED_TOKEN; + command cmd; cmd.type = command::get; @@ -411,21 +428,27 @@ write (sock_fd, &cmd, sizeof (cmd)); if (read (sock_fd, &id, sizeof (id)) != sizeof (id)) - fatal ("protocol error while creating pty using helper process, aborting.\n"); + ptytty_fatal ("protocol error while creating pty using helper process, aborting.\n"); if (!id) - return false; + { + GIVE_TOKEN; + return false; + } - if ((pty = ptytty_recv_fd (sock_fd)) < 0 - || (tty = ptytty_recv_fd (sock_fd)) < 0) - fatal ("protocol error while reading pty/tty fds from helper process, aborting.\n"); + if ((pty = recv_fd (sock_fd)) < 0 + || (tty = recv_fd (sock_fd)) < 0) + ptytty_fatal ("protocol error while reading pty/tty fds from helper process, aborting.\n"); + GIVE_TOKEN; return true; } void ptytty_proxy::login (int cmd_pid, bool login_shell, const char *hostname) { + NEED_TOKEN; + command cmd; cmd.type = command::login; @@ -435,18 +458,24 @@ strncpy (cmd.hostname, hostname, sizeof (cmd.hostname)); write (sock_fd, &cmd, sizeof (cmd)); + + GIVE_TOKEN; } ptytty_proxy::~ptytty_proxy () { if (id) { + NEED_TOKEN; + command cmd; cmd.type = command::destroy; cmd.id = id; write (sock_fd, &cmd, sizeof (cmd)); + + GIVE_TOKEN; } } @@ -456,8 +485,13 @@ command cmd; vector ptys; - while (read (sock_fd, &cmd, sizeof (command)) == sizeof (command)) + for (;;) { + GIVE_TOKEN; + + if (read (sock_fd, &cmd, sizeof (command)) != sizeof (command)) + break; + if (cmd.type == command::get) { // -> id ptyfd ttyfd @@ -468,8 +502,8 @@ write (sock_fd, &cmd.id, sizeof (cmd.id)); ptys.push_back (cmd.id); - ptytty_send_fd (sock_fd, cmd.id->pty); - ptytty_send_fd (sock_fd, cmd.id->tty); + ptytty::send_fd (sock_fd, cmd.id->pty); + ptytty::send_fd (sock_fd, cmd.id->tty); } else { @@ -481,7 +515,7 @@ else if (cmd.type == command::login) { #if UTMP_SUPPORT - if (find (ptys.begin (), ptys.end (), cmd.id)) + if (find (ptys.begin (), ptys.end (), cmd.id) != ptys.end ()) { cmd.hostname[sizeof (cmd.hostname) - 1] = 0; cmd.id->login (cmd.cmd_pid, cmd.login_shell, cmd.hostname); @@ -490,9 +524,9 @@ } else if (cmd.type == command::destroy) { - ptytty **pty = find (ptys.begin (), ptys.end (), cmd.id); + vector::iterator pty = find (ptys.begin (), ptys.end (), cmd.id); - if (pty) + if (pty != ptys.end ()) { delete *pty; ptys.erase (pty); @@ -500,39 +534,79 @@ } else break; + + NEED_TOKEN; } // destroy all ptys - for (ptytty **i = ptys.end (); i-- > ptys.begin (); ) + for (vector::iterator i = ptys.end (); i-- > ptys.begin (); ) delete *i; } -void ptytty_server () +void +ptytty::use_helper () { +#ifndef PTYTTY_NO_PID_CHECK + int pid = getpid (); +#endif + + if (sock_fd >= 0 +#ifndef PTYTTY_NO_PID_CHECK + && pid == owner_pid +#endif + ) + return; + +#ifndef PTYTTY_NO_PID_CHECK + owner_pid = pid; +#endif + int sv[2]; if (socketpair (AF_UNIX, SOCK_STREAM, 0, sv)) - fatal ("could not create socket to communicate with pty/sessiondb helper, aborting.\n"); + ptytty_fatal ("could not create socket to communicate with pty/sessiondb helper, aborting.\n"); + +#ifdef PTYTTY_REENTRANT + int lv[2]; + + if (socketpair (AF_UNIX, SOCK_STREAM, 0, lv)) + ptytty_fatal ("could not create socket to communicate with pty/sessiondb helper, aborting.\n"); +#endif - pid = fork (); + helper_pid = fork (); - if (pid < 0) - fatal ("could not create pty/sessiondb helper process, aborting.\n"); + if (helper_pid < 0) + ptytty_fatal ("could not create pty/sessiondb helper process, aborting.\n"); - if (pid) + if (helper_pid) { // client, process sock_fd = sv[0]; close (sv[1]); fcntl (sock_fd, F_SETFD, FD_CLOEXEC); +#ifdef PTYTTY_REENTRANT + lock_fd = lv[0]; + close (lv[1]); + fcntl (lock_fd, F_SETFD, FD_CLOEXEC); +#endif } else { // server, pty-helper sock_fd = sv[1]; +#ifdef PTYTTY_REENTRANT + lock_fd = lv[1]; +#endif + + chdir ("/"); + + signal (SIGHUP, SIG_IGN); + signal (SIGTERM, SIG_IGN); + signal (SIGINT, SIG_IGN); + signal (SIGPIPE, SIG_IGN); for (int fd = 0; fd < 1023; fd++) - if (fd != sock_fd) + if (fd != sock_fd && fd != lock_fd) close (fd); serve (); @@ -542,12 +616,15 @@ #endif -// a "factory" *g* ptytty * -new_ptytty () +ptytty::create () { #if PTYTTY_HELPER - if (pid > 0) + if (helper_pid +# ifndef PTYTTY_NO_PID_CHECK + && getpid () == owner_pid +# endif + ) // use helper process return new ptytty_proxy; else @@ -555,5 +632,85 @@ return new ptytty_unix; } -/*----------------------- end-of-file (C source) -----------------------*/ +void +ptytty::init () +{ + uid_t uid = getuid (); + gid_t gid = getgid (); + + // before doing anything else, check for setuid/setgid operation, + // start the helper process and drop privileges + if (uid != geteuid () + || gid != getegid ()) + { +#if PTYTTY_HELPER + use_helper (); +#else + ptytty_warn ("running setuid/setgid without pty helper compiled in, continuing unprivileged.\n"); +#endif + + drop_privileges (); + } +} + +void +ptytty::drop_privileges () +{ + uid_t uid = getuid (); + gid_t gid = getgid (); + + // drop privileges +#if HAVE_SETRESUID + setresgid (gid, gid, gid); + setresuid (uid, uid, uid); +#elif HAVE_SETREUID + setregid (gid, gid); + setreuid (uid, uid); +#elif HAVE_SETUID + setgid (gid); + setuid (uid); +#endif + + if (uid != geteuid () + || gid != getegid ()) + ptytty_fatal ("unable to drop privileges, aborting.\n"); +} +///////////////////////////////////////////////////////////////////////////// +// C API + +#ifndef PTYTTY_NO_C_API + +typedef void *PTYTTY; + +#define DEFINE_METHOD(retval, name, args1, args2) \ +extern "C" retval ptytty_ ## name args1 \ +{ return ((struct ptytty *)ptytty)->name args2; } + +DEFINE_METHOD(int,pty,(PTYTTY ptytty),) +DEFINE_METHOD(int,tty,(PTYTTY ptytty),) +DEFINE_METHOD(int,get,(PTYTTY ptytty),()) +DEFINE_METHOD(void,login,(PTYTTY ptytty, int cmd_pid, bool login_shell, const char *hostname),(cmd_pid,login_shell,hostname)) + +DEFINE_METHOD(void,close_tty,(PTYTTY ptytty),()) +DEFINE_METHOD(int,make_controlling_tty,(PTYTTY ptytty),()) +DEFINE_METHOD(void,set_utf8_mode,(PTYTTY ptytty, int on),(on)) + +#define DEFINE_STATIC(retval, name, args) \ +extern "C" retval ptytty_ ## name args \ +{ return ptytty::name args; } + +DEFINE_STATIC(void,drop_privileges,()) +DEFINE_STATIC(void,use_helper,()) +DEFINE_STATIC(void,init,()) + +DEFINE_STATIC(PTYTTY ,create,()) + +void ptytty_delete (PTYTTY ptytty) +{ + delete (struct ptytty *)ptytty; +} + +// send_fd, recv_fd not exposed + +#endif