File indexing completed on 2024-04-28 15:22:04

 /*
     This file is part of the KDE project, module kdesu.
     SPDX-FileCopyrightText: 1999, 2000 Geert Jansen <jansen@kde.org>
 
     This file contains code from TEShell.C of the KDE konsole.
     SPDX-FileCopyrightText: 1997, 1998 Lars Doelle <lars.doelle@on-line.de>
 
     SPDX-License-Identifier: GPL-2.0-only
 
     process.cpp: Functionality to build a front end to password asking terminal programs.
 */
 
 #include "ptyprocess.h"
 #include "kcookie_p.h"
 #include "ptyprocess_p.h"
 
 #include <config-kdesu.h>
 #include <ksu_debug.h>
 
 #include <cerrno>
 #include <fcntl.h>
 #include <signal.h>
 #include <stdlib.h>
 #include <termios.h>
 #include <unistd.h>
 
 #include <sys/resource.h>
 #include <sys/stat.h>
 #include <sys/time.h>
 #include <sys/wait.h>
 
 #if HAVE_SYS_SELECT_H
 #include <sys/select.h> // Needed on some systems.
 #endif
 
 #include <QFile>
 #include <QStandardPaths>
 
 #include <KConfigGroup>
 #include <KSharedConfig>
 
 extern int kdesuDebugArea();
 
 namespace KDESu
 {
 using namespace KDESuPrivate;
 
 /*
 ** Wait for @p ms milliseconds
 ** @param fd file descriptor
 ** @param ms time to wait in milliseconds
 ** @return
 */
 int PtyProcess::waitMS(int fd, int ms)
 {
     struct timeval tv;
     tv.tv_sec = 0;
     tv.tv_usec = 1000 * ms;
 
     fd_set fds;
     FD_ZERO(&fds);
     FD_SET(fd, &fds);
     return select(fd + 1, &fds, nullptr, nullptr, &tv);
 }
 
 // XXX this function is nonsense:
 // - for our child, we could use waitpid().
 // - the configurability at this place it *complete* braindamage
 /*
 ** Basic check for the existence of @p pid.
 ** Returns true iff @p pid is an extant process.
 */
 bool PtyProcess::checkPid(pid_t pid)
 {
     KSharedConfig::Ptr config = KSharedConfig::openConfig();
     KConfigGroup cg(config, "super-user-command");
     QString superUserCommand = cg.readEntry("super-user-command", "sudo");
     // sudo does not accept signals from user so we except it
     if (superUserCommand == QLatin1String("sudo")) {
         return true;
     } else {
         return kill(pid, 0) == 0;
     }
 }
 
 /*
 ** Check process exit status for process @p pid.
 ** On error (no child, no exit), return Error (-1).
 ** If child @p pid has exited, return its exit status,
 ** (which may be zero).
 ** If child @p has not exited, return NotExited (-2).
 */
 int PtyProcess::checkPidExited(pid_t pid)
 {
     int state;
     int ret;
     ret = waitpid(pid, &state, WNOHANG);
 
     if (ret < 0) {
         qCCritical(KSU_LOG) << "[" << __FILE__ << ":" << __LINE__ << "] "
                             << "waitpid():" << strerror(errno);
         return Error;
     }
     if (ret == pid) {
         if (WIFEXITED(state)) {
             return WEXITSTATUS(state);
         }
 
         return Killed;
     }
 
     return NotExited;
 }
 
 PtyProcess::PtyProcess()
     : PtyProcess(*new PtyProcessPrivate)
 {
 }
 
 PtyProcess::PtyProcess(PtyProcessPrivate &dd)
     : d(&dd)
 {
     m_terminal = false;
     m_erase = false;
 }
 
 PtyProcess::~PtyProcess() = default;
 
 int PtyProcess::init()
 {
     delete d->pty;
     d->pty = new KPty();
     if (!d->pty->open()) {
         qCCritical(KSU_LOG) << "[" << __FILE__ << ":" << __LINE__ << "] "
                             << "Failed to open PTY.";
         return -1;
     }
     if (!d->wantLocalEcho) {
         enableLocalEcho(false);
     }
     d->inputBuffer.resize(0);
     return 0;
 }
 
 /** Set additional environment variables. */
 void PtyProcess::setEnvironment(const QList<QByteArray> &env)
 {
     d->env = env;
 }
 
 int PtyProcess::fd() const
 {
     return d->pty ? d->pty->masterFd() : -1;
 }
 
 int PtyProcess::pid() const
 {
     return m_pid;
 }
 
 /** Returns the additional environment variables set by setEnvironment() */
 QList<QByteArray> PtyProcess::environment() const
 {
     return d->env;
 }
 
 QByteArray PtyProcess::readAll(bool block)
 {
     QByteArray ret;
     if (!d->inputBuffer.isEmpty()) {
         // if there is still something in the buffer, we need not block.
         // we should still try to read any further output, from the fd, though.
         block = false;
         ret = d->inputBuffer;
         d->inputBuffer.resize(0);
     }
 
     int flags = fcntl(fd(), F_GETFL);
     if (flags < 0) {
         qCCritical(KSU_LOG) << "[" << __FILE__ << ":" << __LINE__ << "] "
                             << "fcntl(F_GETFL):" << strerror(errno);
         return ret;
     }
     int oflags = flags;
     if (block) {
         flags &= ~O_NONBLOCK;
     } else {
         flags |= O_NONBLOCK;
     }
 
     if ((flags != oflags) && (fcntl(fd(), F_SETFL, flags) < 0)) {
         // We get an error here when the child process has closed
         // the file descriptor already.
         return ret;
     }
 
     while (1) {
         ret.reserve(ret.size() + 0x8000);
         int nbytes = read(fd(), ret.data() + ret.size(), 0x8000);
         if (nbytes == -1) {
             if (errno == EINTR) {
                 continue;
             } else {
                 break;
             }
         }
         if (nbytes == 0) {
             break; // nothing available / eof
         }
 
         ret.resize(ret.size() + nbytes);
         break;
     }
 
     return ret;
 }
 
 QByteArray PtyProcess::readLine(bool block)
 {
     d->inputBuffer = readAll(block);
 
     int pos;
     QByteArray ret;
     if (!d->inputBuffer.isEmpty()) {
         pos = d->inputBuffer.indexOf('\n');
         if (pos == -1) {
             // NOTE: this means we return something even if there in no full line!
             ret = d->inputBuffer;
             d->inputBuffer.resize(0);
         } else {
             ret = d->inputBuffer.left(pos);
             d->inputBuffer.remove(0, pos + 1);
         }
     }
 
     return ret;
 }
 
 void PtyProcess::writeLine(const QByteArray &line, bool addnl)
 {
     if (!line.isEmpty()) {
         write(fd(), line.constData(), line.length());
     }
     if (addnl) {
         write(fd(), "\n", 1);
     }
 }
 
 void PtyProcess::unreadLine(const QByteArray &line, bool addnl)
 {
     QByteArray tmp = line;
     if (addnl) {
         tmp += '\n';
     }
     if (!tmp.isEmpty()) {
         d->inputBuffer.prepend(tmp);
     }
 }
 
 void PtyProcess::setExitString(const QByteArray &exit)
 {
     m_exitString = exit;
 }
 
 /*
  * Fork and execute the command. This returns in the parent.
  */
 int PtyProcess::exec(const QByteArray &command, const QList<QByteArray> &args)
 {
     int i;
 
     if (init() < 0) {
         return -1;
     }
 
     if ((m_pid = fork()) == -1) {
         qCCritical(KSU_LOG) << "[" << __FILE__ << ":" << __LINE__ << "] "
                             << "fork():" << strerror(errno);
         return -1;
     }
 
     // Parent
     if (m_pid) {
         d->pty->closeSlave();
         return 0;
     }
 
     // Child
     if (setupTTY() < 0) {
         _exit(1);
     }
 
     for (const QByteArray &var : std::as_const(d->env)) {
         putenv(const_cast<char *>(var.constData()));
     }
     unsetenv("KDE_FULL_SESSION");
     // for : Qt: Session management error
     unsetenv("SESSION_MANAGER");
     // QMutex::lock , deadlocks without that.
     // <thiago> you cannot connect to the user's session bus from another UID
     unsetenv("DBUS_SESSION_BUS_ADDRESS");
 
     // set temporarily LC_ALL to C, for su (to be able to parse "Password:")
     const QByteArray old_lc_all = qgetenv("LC_ALL");
     if (!old_lc_all.isEmpty()) {
         qputenv("KDESU_LC_ALL", old_lc_all);
     } else {
         unsetenv("KDESU_LC_ALL");
     }
     qputenv("LC_ALL", "C");
 
     // From now on, terminal output goes through the tty.
 
     QByteArray path;
     if (command.contains('/')) {
         path = command;
     } else {
         QString file = QStandardPaths::findExecutable(QFile::decodeName(command));
         if (file.isEmpty()) {
             qCCritical(KSU_LOG) << "[" << __FILE__ << ":" << __LINE__ << "] " << command << "not found.";
             _exit(1);
         }
         path = QFile::encodeName(file);
     }
 
     const char **argp = (const char **)malloc((args.count() + 2) * sizeof(char *));
 
     i = 0;
     argp[i++] = path.constData();
     for (const QByteArray &arg : args) {
         argp[i++] = arg.constData();
     }
 
     argp[i] = nullptr;
 
     execv(path.constData(), const_cast<char **>(argp));
     qCCritical(KSU_LOG) << "[" << __FILE__ << ":" << __LINE__ << "] "
                         << "execv(" << path << "):" << strerror(errno);
     _exit(1);
     return -1; // Shut up compiler. Never reached.
 }
 
 /*
  * Wait until the terminal is set into no echo mode. At least one su
  * (RH6 w/ Linux-PAM patches) sets noecho mode AFTER writing the Password:
  * prompt, using TCSAFLUSH. This flushes the terminal I/O queues, possibly
  * taking the password  with it. So we wait until no echo mode is set
  * before writing the password.
  * Note that this is done on the slave fd. While Linux allows tcgetattr() on
  * the master side, Solaris doesn't.
  */
 int PtyProcess::waitSlave()
 {
     struct termios tio;
     while (1) {
         if (!checkPid(m_pid)) {
             qCCritical(KSU_LOG) << "process has exited while waiting for password.";
             return -1;
         }
         if (!d->pty->tcGetAttr(&tio)) {
             qCCritical(KSU_LOG) << "[" << __FILE__ << ":" << __LINE__ << "] "
                                 << "tcgetattr():" << strerror(errno);
             return -1;
         }
         if (tio.c_lflag & ECHO) {
             // qDebug() << "[" << __FILE__ << ":" << __LINE__ << "] " << "Echo mode still on.";
             usleep(10000);
             continue;
         }
         break;
     }
     return 0;
 }
 
 int PtyProcess::enableLocalEcho(bool enable)
 {
     d->wantLocalEcho = enable;
     if (!d->pty) {
         // Apply it on init
         return 0;
     }
 
     return d->pty->setEcho(enable) ? 0 : -1;
 }
 
 void PtyProcess::setTerminal(bool terminal)
 {
     m_terminal = terminal;
 }
 
 void PtyProcess::setErase(bool erase)
 {
     m_erase = erase;
 }
 
 /*
  * Copy output to stdout until the child process exits, or a line of output
  * matches `m_exitString'.
  * We have to use waitpid() to test for exit. Merely waiting for EOF on the
  * pty does not work, because the target process may have children still
  * attached to the terminal.
  */
 int PtyProcess::waitForChild()
 {
     fd_set fds;
     FD_ZERO(&fds);
     QByteArray remainder;
 
     while (1) {
         FD_SET(fd(), &fds);
 
         // specify timeout to make sure select() does not block, even if the
         // process is dead / non-responsive. It does not matter if we abort too
         // early. In that case 0 is returned, and we'll try again in the next
         // iteration. (As long as we don't consistently time out in each iteration)
         timeval timeout;
         timeout.tv_sec = 0;
         timeout.tv_usec = 100000;
         int ret = select(fd() + 1, &fds, nullptr, nullptr, &timeout);
         if (ret == -1) {
             if (errno != EINTR) {
                 qCCritical(KSU_LOG) << "[" << __FILE__ << ":" << __LINE__ << "] "
                                     << "select():" << strerror(errno);
                 return -1;
             }
             ret = 0;
         }
 
         if (ret) {
             for (;;) {
                 QByteArray output = readAll(false);
                 if (output.isEmpty()) {
                     break;
                 }
                 if (m_terminal) {
                     fwrite(output.constData(), output.size(), 1, stdout);
                     fflush(stdout);
                 }
                 if (!m_exitString.isEmpty()) {
                     // match exit string only at line starts
                     remainder += output;
                     while (remainder.length() >= m_exitString.length()) {
                         if (remainder.startsWith(m_exitString)) {
                             kill(m_pid, SIGTERM);
                             remainder.remove(0, m_exitString.length());
                         }
                         int off = remainder.indexOf('\n');
                         if (off < 0) {
                             break;
                         }
                         remainder.remove(0, off + 1);
                     }
                 }
             }
         }
 
         ret = checkPidExited(m_pid);
         if (ret == Error) {
             if (errno == ECHILD) {
                 return 0;
             } else {
                 return 1;
             }
         } else if (ret == Killed) {
             return 0;
         } else if (ret == NotExited) {
             continue; // keep checking
         } else {
             return ret;
         }
     }
 }
 
 /*
  * SetupTTY: Creates a new session. The filedescriptor "fd" should be
  * connected to the tty. It is closed after the tty is reopened to make it
  * our controlling terminal. This way the tty is always opened at least once
  * so we'll never get EIO when reading from it.
  */
 int PtyProcess::setupTTY()
 {
     // Reset signal handlers
     for (int sig = 1; sig < NSIG; sig++) {
         signal(sig, SIG_DFL);
     }
     signal(SIGHUP, SIG_IGN);
 
     d->pty->setCTty();
 
     // Connect stdin, stdout and stderr
     int slave = d->pty->slaveFd();
     dup2(slave, 0);
     dup2(slave, 1);
     dup2(slave, 2);
 
     // Close all file handles
     // XXX this caused problems in KProcess - not sure why anymore. -- ???
     // Because it will close the start notification pipe. -- ossi
     struct rlimit rlp;
     getrlimit(RLIMIT_NOFILE, &rlp);
     for (int i = 3; i < (int)rlp.rlim_cur; i++) {
         close(i);
     }
 
     // Disable OPOST processing. Otherwise, '\n' are (on Linux at least)
     // translated to '\r\n'.
     struct ::termios tio;
     if (tcgetattr(0, &tio) < 0) {
         qCCritical(KSU_LOG) << "[" << __FILE__ << ":" << __LINE__ << "] "
                             << "tcgetattr():" << strerror(errno);
         return -1;
     }
     tio.c_oflag &= ~OPOST;
     if (tcsetattr(0, TCSANOW, &tio) < 0) {
         qCCritical(KSU_LOG) << "[" << __FILE__ << ":" << __LINE__ << "] "
                             << "tcsetattr():" << strerror(errno);
         return -1;
     }
 
     return 0;
 }
 
 void PtyProcess::virtual_hook(int id, void *data)
 {
     Q_UNUSED(id);
     Q_UNUSED(data);
     /*BASE::virtual_hook( id, data );*/
 }
 
 } // namespace KDESu