# 
# AUTHOR <EMAIL@ADDRESS>, YEAR.
#
msgid ""
msgstr ""
"Project-Id-Version: 0\n"
"POT-Creation-Date: 2013-03-12T03:19:44\n"
"PO-Revision-Date: 2013-03-12T03:19:44\n"
"Last-Translator: Automatically generated\n"
"Language-Team: None\n"
"MIME-Version: 1.0\n"
"Content-Type: application/x-publican; charset=UTF-8\n"
"Content-Transfer-Encoding: 8bit\n"

#. Tag: title
#, no-c-format
msgid "Processes"
msgstr ""

#. Tag: title
#, no-c-format
msgid "Safe process creation"
msgstr ""

#. Tag: para
#, no-c-format
msgid "This section describes how to create new child processes in a safe manner. In addition to the concerns addressed below, there is the possibility of file descriptor leaks, see <xref linkend=\"sect-Defensive_Coding-Tasks-Descriptors-Child_Processes\" />."
msgstr ""

#. Tag: title
#, no-c-format
msgid "Obtaining the program path and the command line template"
msgstr ""

#. Tag: para
#, no-c-format
msgid "The name and path to the program being invoked should be hard-coded or controlled by a static configuration file stored at a fixed location (at an file system absolute path). The same applies to the template for generating the command line."
msgstr ""

#. Tag: para
#, no-c-format
msgid "The configured program name should be an absolute path. If it is a relative path, the contents of the <envar>PATH</envar> must be obtained in s secure manner (see <xref linkend=\"sect-Defensive_Coding-Tasks-secure_getenv\" />). If the <envar>PATH</envar> variable is not set or untrusted, the safe default <literal>/bin:/usr/bin</literal> must be used."
msgstr ""

#. Tag: para
#, no-c-format
msgid "If too much flexibility is provided here, it may allow invocation of arbitrary programs without proper authorization."
msgstr ""

#. Tag: title
#, no-c-format
msgid "Bypassing the shell"
msgstr ""

#. Tag: para
#, no-c-format
msgid "Child processes should be created without involving the system shell."
msgstr ""

#. Tag: para
#, no-c-format
msgid "For C/C++, <function>system</function> should not be used. The <function>posix_spawn</function> function can be used instead, or a combination <function>fork</function> and <function>execve</function>. (In some cases, it may be preferable to use <function>vfork</function> or the Linux-specific <function>clone</function> system call instead of <function>fork</function>.)"
msgstr ""

#. Tag: para
#, no-c-format
msgid "In Python, the <literal>subprocess</literal> module bypasses the shell by default (when the <literal>shell</literal> keyword argument is not set to true). <function>os.system</function> should not be used."
msgstr ""

#. Tag: para
#, no-c-format
msgid "The Java class <type>java.lang.ProcessBuilder</type> can be used to create subprocesses without interference from the system shell."
msgstr ""

#. Tag: title
#, no-c-format
msgid "Portability notice"
msgstr ""

#. Tag: para
#, no-c-format
msgid "On Windows, there is no argument vector, only a single argument string. Each application is responsible for parsing this string into an argument vector. There is considerable variance among the quoting style recognized by applications. Some of them expand shell wildcards, others do not. Extensive application-specific testing is required to make this secure."
msgstr ""

#. Tag: para
#, no-c-format
msgid "Note that some common applications (notably <application>ssh</application>) unconditionally introduce the use of a shell, even if invoked directly without a shell. It is difficult to use these applications in a secure manner. In this case, untrusted data should be supplied by other means. For example, standard input could be used, instead of the command line."
msgstr ""

#. Tag: title
#, no-c-format
msgid "Specifying the process environment"
msgstr ""

#. Tag: para
#, no-c-format
msgid "Child processes should be created with a minimal set of environment variables. This is absolutely essential if there is a trust transition involved, either when the parent process was created, or during the creation of the child process."
msgstr ""

#. Tag: para
#, no-c-format
msgid "In C/C++, the environment should be constructed as an array of strings and passed as the <varname>envp</varname> argument to <function>posix_spawn</function> or <function>execve</function>. The functions <function>setenv</function>, <function>unsetenv</function> and <function>putenv</function> should not be used. They are not thread-safe and suffer from memory leaks."
msgstr ""

#. Tag: para
#, no-c-format
msgid "Python programs need to specify a <literal>dict</literal> for the the <varname>env</varname> argument of the <function>subprocess.Popen</function> constructor. The Java class <literal>java.lang.ProcessBuilder</literal> provides a <function>environment()</function> method, which returns a map that can be manipulated."
msgstr ""

#. Tag: para
#, no-c-format
msgid "The following list provides guidelines for selecting the set of environment variables passed to the child process."
msgstr ""

#. Tag: para
#, no-c-format
msgid "<envar>PATH</envar> should be initialized to <literal>/bin:/usr/bin</literal>."
msgstr ""

#. Tag: para
#, no-c-format
msgid "<envar>USER</envar> and <envar>HOME</envar> can be inhereted from the parent process environment, or they can be initialized from the <literal>pwent</literal> structure for the user."
msgstr ""

#. Tag: para
#, no-c-format
msgid "The <envar>DISPLAY</envar> and <envar>XAUTHORITY</envar> variables should be passed to the subprocess if it is an X program. Note that this will typically not work across trust boundaries because <envar>XAUTHORITY</envar> refers to a file with <literal>0600</literal> permissions."
msgstr ""

#. Tag: para
#, no-c-format
msgid "The location-related environment variables <envar>LANG</envar>, <envar>LANGUAGE</envar>, <envar>LC_ADDRESS</envar>, <envar>LC_ALL</envar>, <envar>LC_COLLATE</envar>, <envar>LC_CTYPE</envar>, <envar>LC_IDENTIFICATION</envar>, <envar>LC_MEASUREMENT</envar>, <envar>LC_MESSAGES</envar>, <envar>LC_MONETARY</envar>, <envar>LC_NAME</envar>, <envar>LC_NUMERIC</envar>, <envar>LC_PAPER</envar>, <envar>LC_TELEPHONE</envar> and <envar>LC_TIME</envar> can be passed to the subprocess if present."
msgstr ""

#. Tag: para
#, no-c-format
msgid "The called process may need application-specific environment variables, for example for passing passwords. (See <xref linkend=\"sect-Defensive_Coding-Tasks-Processes-Command_Line_Visibility\" />.)"
msgstr ""

#. Tag: para
#, no-c-format
msgid "All other environment variables should be dropped. Names for new environment variables should not be accepted from untrusted sources."
msgstr ""

#. Tag: title
#, no-c-format
msgid "Robust argument list processing"
msgstr ""

#. Tag: para
#, no-c-format
msgid "When invoking a program, it is sometimes necessary to include data from untrusted sources. Such data should be check against embedded <literal>NUL</literal> characters because the system APIs will sliently truncate argument strings at the first <literal>NUL</literal> character."
msgstr ""

#. Tag: para
#, no-c-format
msgid "The following recommendations assume that the program being invoked uses GNU-style option processing using <function>getopt_long</function>. This convention is widely used, but it is just that, and individual programs might interpret a command line in a different way."
msgstr ""

#. Tag: para
#, no-c-format
msgid "If the untrusted data has to go into an option, use the <literal>--option-name=VALUE</literal> syntax, placing the option and its value into the same command line argument. This avoids any potential confusion if the data starts with <literal>-</literal>."
msgstr ""

#. Tag: para
#, no-c-format
msgid "For positional arguments, terminate the option list with a single <option>--</option> marker after the last option, and include the data at the right position. The <option>--</option> marker terminates option processing, and the data will not be treated as an option even if it starts with a dash."
msgstr ""

#. Tag: title
#, no-c-format
msgid "Passing secrets to subprocesses"
msgstr ""

#. Tag: para
#, no-c-format
msgid "The command line (the name of the program and its argument) of a running process is traditionally available to all local users. The called program can overwrite this information, but only after it has run for a bit of time, during which the information may have been read by other processes. However, on Linux, the process environment is restricted to the user who runs the process. Therefore, if you need a convenient way to pass a password to a child process, use an environment variable, and not a command line argument. (See <xref linkend=\"sect-Defensive_Coding-Tasks-Processes-environ\" />.)"
msgstr ""

#. Tag: para
#, no-c-format
msgid "On some UNIX-like systems (notably Solaris), environment variables can be read by any system user, just like command lines."
msgstr ""

#. Tag: para
#, no-c-format
msgid "If the environment-based approach cannot be used due to portability concerns, the data can be passed on standard input. Some programs (notably <application>gpg</application>) use special file descriptors whose numbers are specified on the command line. Temporary files are an option as well, but they might give digital forensics access to sensitive data (such as passphrases) because it is difficult to safely delete them in all cases."
msgstr ""

#. Tag: title
#, no-c-format
msgid "Handling child process termination"
msgstr ""

#. Tag: para
#, no-c-format
msgid "When child processes terminate, the parent process is signalled. A stub of the terminated processes (a <emphasis>zombie</emphasis>, shown as <literal>&lt;defunct&gt;</literal> by <application>ps</application>) is kept around until the status information is collected (<emphasis>reaped</emphasis>) by the parent process. Over the years, several interfaces for this have been invented:"
msgstr ""

#. Tag: para
#, no-c-format
msgid "The parent process calls <function>wait</function>, <function>waitpid</function>, <function>waitid</function>, <function>wait3</function> or <function>wait4</function>, without specifying a process ID. This will deliver any matching process ID. This approach is typically used from within event loops."
msgstr ""

#. Tag: para
#, no-c-format
msgid "The parent process calls <function>waitpid</function>, <function>waitid</function>, or <function>wait4</function>, with a specific process ID. Only data for the specific process ID is returned. This is typically used in code which spawns a single subprocess in a synchronous manner."
msgstr ""

#. Tag: para
#, no-c-format
msgid "The parent process installs a handler for the <literal>SIGCHLD</literal> signal, using <function>sigaction</function>, and specifies to the <literal>SA_NOCLDWAIT</literal> flag. This approach could be used by event loops as well."
msgstr ""

#. Tag: para
#, no-c-format
msgid "None of these approaches can be used to wait for child process terminated in a completely thread-safe manner. The parent process might execute an event loop in another thread, which could pick up the termination signal. This means that libraries typically cannot make free use of child processes (for example, to run problematic code with reduced privileges in a separate address space)."
msgstr ""

#. Tag: para
#, no-c-format
msgid "At the moment, the parent process should explicitly wait for termination of the child process using <function>waitpid</function> or <function>waitpid</function>, and hope that the status is not collected by an event loop first."
msgstr ""

#. Tag: title
#, no-c-format
msgid "<literal>SUID</literal>/<literal>SGID</literal> processes"
msgstr ""

#. Tag: para
#, no-c-format
msgid "Programs can be marked in the file system to indicate to the kernel that a trust transition should happen if the program is run. The <literal>SUID</literal> file permission bit indicates that an executable should run with the effective user ID equal to the owner of the executable file. Similarly, with the <literal>SGID</literal> bit, the effective group ID is set to the group of the executable file."
msgstr ""

#. Tag: para
#, no-c-format
msgid "Linux supports <emphasis>fscaps</emphasis>, which can grant additional capabilities to a process in a finer-grained manner. Additional mechanisms can be provided by loadable security modules."
msgstr ""

#. Tag: para
#, no-c-format
msgid "When such a trust transition has happened, the process runs in a potentially hostile environment. Additional care is necessary not to rely on any untrusted information. These concerns also apply to libraries which can be linked into such processes."
msgstr ""

#. Tag: title
#, no-c-format
msgid "Accessing environment variables"
msgstr ""

#. Tag: para
#, no-c-format
msgid "The following steps are required so that a program does not accidentally pick up untrusted data from environment variables."
msgstr ""

#. Tag: para
#, no-c-format
msgid "Compile your C/C++ sources with <literal>-D_GNU_SOURCE</literal>. The Autoconf macro <literal>AC_GNU_SOURCE</literal> ensures this."
msgstr ""

#. Tag: para
#, no-c-format
msgid "Check for the presence of the <function>secure_getenv</function> and <function>__secure_getenv</function> function. The Autoconf directive <literal>AC_CHECK_FUNCS([__secure_getenv secure_getenv])</literal> performs these checks."
msgstr ""

#. Tag: para
#, no-c-format
msgid "Arrange for a proper definition of the <function>secure_getenv</function> function. See <xref linkend=\"ex-Defensive_Coding-Tasks-secure_getenv\" />."
msgstr ""

#. Tag: para
#, no-c-format
msgid "Use <function>secure_getenv</function> instead of <function>getenv</function> to obtain the value of critical environment variables. <function>secure_getenv</function> will pretend the variable has not bee set if the process environment is not trusted."
msgstr ""

#. Tag: para
#, no-c-format
msgid "Critical environment variables are debugging flags, configuration file locations, plug-in and log file locations, and anything else that might be used to bypass security restrictions or cause a privileged process to behave in an unexpected way."
msgstr ""

#. Tag: para
#, no-c-format
msgid "Either the <function>secure_getenv</function> function or the <function>__secure_getenv</function> is available from GNU libc."
msgstr ""

#. Tag: title
#, no-c-format
msgid "Obtaining a definition for <function>secure_getenv</function>"
msgstr ""

#. Tag: programlisting
#, no-c-format
msgid "\n"
"\n"
"#include &lt;stdlib.h&gt;\n"
"\n"
"#ifndef HAVE_SECURE_GETENV\n"
"#  ifdef HAVE__SECURE_GETENV\n"
"#    define secure_getenv __secure_getenv\n"
"#  else\n"
"#    error neither secure_getenv nor __secure_getenv are available\n"
"#  endif\n"
"#endif\n"
"\n"
"	"
msgstr ""

#. Tag: title
#, no-c-format
msgid "Daemons"
msgstr ""

#. Tag: para
#, no-c-format
msgid "Background processes providing system services (<emphasis>daemons</emphasis>) need to decouple themselves from the controlling terminal and the parent process environment:"
msgstr ""

#. Tag: para
#, no-c-format
msgid "Fork."
msgstr ""

#. Tag: para
#, no-c-format
msgid "In the child process, call <function>setsid</function>. The parent process can simply exit (using <function>_exit</function>, to avoid running clean-up actions twice)."
msgstr ""

#. Tag: para
#, no-c-format
msgid "In the child process, fork again. Processing continues in the child process. Again, the parent process should just exit."
msgstr ""

#. Tag: para
#, no-c-format
msgid "Replace the descriptors 0, 1, 2 with a descriptor for <filename>/dev/null</filename>. Logging should be redirected to <application>syslog</application>."
msgstr ""

#. Tag: para
#, no-c-format
msgid "Older instructions for creating daemon processes recommended a call to <literal>umask(0)</literal>. This is risky because it often leads to world-writable files and directories, resulting in security vulnerabilities such as arbitrary process termination by untrusted local users, or log file truncation. If the <emphasis>umask</emphasis> needs setting, a restrictive value such as <literal>027</literal> or <literal>077</literal> is recommended."
msgstr ""

#. Tag: para
#, no-c-format
msgid "Other aspects of the process environment may have to changed as well (environment variables, signal handler disposition)."
msgstr ""

#. Tag: para
#, no-c-format
msgid "It is increasingly common that server processes do not run as background processes, but as regular foreground process under a supervising master process (such as <application>systemd</application>). Server processes should offer a command line option which disables forking and replacement of the standard output and standard error streams. Such an option is also useful for debugging."
msgstr ""

#. Tag: title
#, no-c-format
msgid "Semantics of command line arguments"
msgstr ""

#. Tag: para
#, no-c-format
msgid "After process creation and option processing, it is up to the child process to interpret the arguments. Arguments can be file names, host names, or URLs, and many other things. URLs can refer to the local network, some server on the Internet, or to the local file system. Some applications even accept arbitrary code in arguments (for example, <application>python</application> with the <option>-c</option> option)."
msgstr ""

#. Tag: para
#, no-c-format
msgid "Similar concerns apply to environment variables, the contents of the current directory and its subdirectories."
msgstr ""

#. Tag: para
#, no-c-format
msgid "Consequently, careful analysis is required if it is safe to pass untrusted data to another program."
msgstr ""

#. Tag: title
#, no-c-format
msgid "<function>fork</function> as a primitive for parallelism"
msgstr ""

#. Tag: para
#, no-c-format
msgid "A call to <function>fork</function> which is not immediately followed by a call to <function>execve</function> (perhaps after rearranging and closing file descriptors) is typically unsafe, especially from a library which does not control the state of the entire process. Such use of <function>fork</function> should be replaced with proper child processes or threads."
msgstr ""

