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