includes/shell/Shell.php

   1 <?php
   2 /**
   3  * Class used for executing shell commands
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  */
  22
  23 namespace MediaWiki\Shell;
  24
  25 use MediaWiki\MediaWikiServices;
  26
  27 /**
  28  * Executes shell commands
  29  *
  30  * @since 1.30
  31  *
  32  * Use call chaining with this class for expressiveness:
  33  *  $result = Shell::command( 'some command' )
  34  *       ->input( 'foo' )
  35  *       ->environment( [ 'ENVIRONMENT_VARIABLE' => 'VALUE' ] )
  36  *       ->limits( [ 'time' => 300 ] )
  37  *       ->execute();
  38  *
  39  *  ... = $result->getExitCode();
  40  *  ... = $result->getStdout();
  41  *  ... = $result->getStderr();
  42  */
  43 class Shell {
  44
  45         /**
  46          * Apply a default set of restrictions for improved
  47          * security out of the box.
  48          *
  49          * Equal to NO_ROOT | SECCOMP | PRIVATE_DEV | NO_LOCALSETTINGS
  50          *
  51          * @note This value will change over time to provide increased security
  52          *       by default, and is not guaranteed to be backwards-compatible.
  53          * @since 1.31
  54          */
  55         const RESTRICT_DEFAULT = 39;
  56
  57         /**
  58          * Disallow any root access. Any setuid binaries
  59          * will be run without elevated access.
  60          *
  61          * @since 1.31
  62          */
  63         const NO_ROOT = 1;
  64
  65         /**
  66          * Use seccomp to block dangerous syscalls
  67          * @see <https://en.wikipedia.org/wiki/seccomp>
  68          *
  69          * @since 1.31
  70          */
  71         const SECCOMP = 2;
  72
  73         /**
  74          * Create a private /dev
  75          *
  76          * @since 1.31
  77          */
  78         const PRIVATE_DEV = 4;
  79
  80         /**
  81          * Restrict the request to have no
  82          * network access
  83          *
  84          * @since 1.31
  85          */
  86         const NO_NETWORK = 8;
  87
  88         /**
  89          * Deny execve syscall with seccomp
  90          * @see <https://en.wikipedia.org/wiki/exec_(system_call)>
  91          *
  92          * @since 1.31
  93          */
  94         const NO_EXECVE = 16;
  95
  96         /**
  97          * Deny access to LocalSettings.php (MW_CONFIG_FILE)
  98          *
  99          * @since 1.31
 100          */
 101         const NO_LOCALSETTINGS = 32;
 102
 103         /**
 104          * Returns a new instance of Command class
 105          *
 106          * @param string|string[] $command String or array of strings representing the command to
 107          * be executed, each value will be escaped.
 108          *   Example:   [ 'convert', '-font', 'font name' ] would produce "'convert' '-font' 'font name'"
 109          * @return Command
 110          */
 111         public static function command( $command ) {
 112                 $args = func_get_args();
 113                 if ( count( $args ) === 1 && is_array( reset( $args ) ) ) {
 114                         // If only one argument has been passed, and that argument is an array,
 115                         // treat it as a list of arguments
 116                         $args = reset( $args );
 117                 }
 118                 $command = MediaWikiServices::getInstance()
 119                         ->getShellCommandFactory()
 120                         ->create();
 121
 122                 return $command->params( $args );
 123         }
 124
 125         /**
 126          * Check if this class is effectively disabled via php.ini config
 127          *
 128          * @return bool
 129          */
 130         public static function isDisabled() {
 131                 static $disabled = null;
 132
 133                 if ( is_null( $disabled ) ) {
 134                         if ( !function_exists( 'proc_open' ) ) {
 135                                 wfDebug( "proc_open() is disabled\n" );
 136                                 $disabled = true;
 137                         } else {
 138                                 $disabled = false;
 139                         }
 140                 }
 141
 142                 return $disabled;
 143         }
 144
 145         /**
 146          * Version of escapeshellarg() that works better on Windows.
 147          *
 148          * Originally, this fixed the incorrect use of single quotes on Windows
 149          * (https://bugs.php.net/bug.php?id=26285) and the locale problems on Linux in
 150          * PHP 5.2.6+ (bug backported to earlier distro releases of PHP).
 151          *
 152          * @param string $args,... strings to escape and glue together, or a single array of
 153          *     strings parameter. Null values are ignored.
 154          * @return string
 155          */
 156         public static function escape( /* ... */ ) {
 157                 $args = func_get_args();
 158                 if ( count( $args ) === 1 && is_array( reset( $args ) ) ) {
 159                         // If only one argument has been passed, and that argument is an array,
 160                         // treat it as a list of arguments
 161                         $args = reset( $args );
 162                 }
 163
 164                 $first = true;
 165                 $retVal = '';
 166                 foreach ( $args as $arg ) {
 167                         if ( $arg === null ) {
 168                                 continue;
 169                         }
 170                         if ( !$first ) {
 171                                 $retVal .= ' ';
 172                         } else {
 173                                 $first = false;
 174                         }
 175
 176                         if ( wfIsWindows() ) {
 177                                 // Escaping for an MSVC-style command line parser and CMD.EXE
 178                                 // Refs:
 179                                 //  * https://web.archive.org/web/20020708081031/http://mailman.lyra.org/pipermail/scite-interest/2002-March/000436.html
 180                                 //  * https://technet.microsoft.com/en-us/library/cc723564.aspx
 181                                 //  * T15518
 182                                 //  * CR r63214
 183                                 // Double the backslashes before any double quotes. Escape the double quotes.
 184                                 $tokens = preg_split( '/(\\\\*")/', $arg, -1, PREG_SPLIT_DELIM_CAPTURE );
 185                                 $arg = '';
 186                                 $iteration = 0;
 187                                 foreach ( $tokens as $token ) {
 188                                         if ( $iteration % 2 == 1 ) {
 189                                                 // Delimiter, a double quote preceded by zero or more slashes
 190                                                 $arg .= str_replace( '\\', '\\\\', substr( $token, 0, -1 ) ) . '\\"';
 191                                         } elseif ( $iteration % 4 == 2 ) {
 192                                                 // ^ in $token will be outside quotes, need to be escaped
 193                                                 $arg .= str_replace( '^', '^^', $token );
 194                                         } else { // $iteration % 4 == 0
 195                                                 // ^ in $token will appear inside double quotes, so leave as is
 196                                                 $arg .= $token;
 197                                         }
 198                                         $iteration++;
 199                                 }
 200                                 // Double the backslashes before the end of the string, because
 201                                 // we will soon add a quote
 202                                 $m = [];
 203                                 if ( preg_match( '/^(.*?)(\\\\+)$/', $arg, $m ) ) {
 204                                         $arg = $m[1] . str_replace( '\\', '\\\\', $m[2] );
 205                                 }
 206
 207                                 // Add surrounding quotes
 208                                 $retVal .= '"' . $arg . '"';
 209                         } else {
 210                                 $retVal .= escapeshellarg( $arg );
 211                         }
 212                 }
 213                 return $retVal;
 214         }
 215 }