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  1. This patch is based on http://kyberdigi.cz/projects/execdir/ but instead trying
  2. to sanitize the exec command string inside PHP this job is handled by bash and
  3. a special restricted PHP-mode which strips off all path informations.
  4.  
  5. This patch depends on:
  6. - bash restricted php mode patch
  7.   https://manuel.mausz.at/coding/patches/php/bash-4.2-restricted-php.patch
  8.  
  9. No warranty!
  10. diff -Naur php-7.4.4.orig/ext/standard/exec.c php-7.4.4/ext/standard/exec.c
  11. --- php-7.4.4.orig/ext/standard/exec.c	2020-03-17 11:40:33.000000000 +0100
  12. +++ php-7.4.4/ext/standard/exec.c	2020-03-19 14:36:43.456447593 +0100
  13. @@ -96,21 +96,30 @@
  14.  	char *buf;
  15.  	size_t l = 0;
  16.  	int pclose_return;
  17. -	char *b, *d=NULL;
  18. +	char *cmd_p, *b, *d=NULL;
  19.  	php_stream *stream;
  20.  	size_t buflen, bufl = 0;
  21.  #if PHP_SIGCHILD
  22.  	void (*sig_handler)() = NULL;
  23.  #endif
  24.  
  25. +	if (PG(exec_dir) && strlen(PG(exec_dir))) {
  26. +		zend_string *cmd_esc = php_escape_shell_arg(cmd);
  27. +		spprintf(&d, 0, "PATH=%s /bin/bash --php -rc %s", PG(exec_dir), ZSTR_VAL(cmd_esc));
  28. +		zend_string_release(cmd_esc);
  29. +		cmd_p = d;
  30. +	} else {
  31. +		cmd_p = cmd;
  32. +	}
  33. +
  34.  #if PHP_SIGCHILD
  35.  	sig_handler = signal (SIGCHLD, SIG_DFL);
  36.  #endif
  37.  
  38.  #ifdef PHP_WIN32
  39. -	fp = VCWD_POPEN(cmd, "rb");
  40. +	fp = VCWD_POPEN(cmd_p, "rb");
  41.  #else
  42. -	fp = VCWD_POPEN(cmd, "r");
  43. +	fp = VCWD_POPEN(cmd_p, "r");
  44.  #endif
  45.  	if (!fp) {
  46.  		php_error_docref(NULL, E_WARNING, "Unable to fork [%s]", cmd);
  47. @@ -521,7 +530,7 @@
  48.  PHP_FUNCTION(shell_exec)
  49.  {
  50.  	FILE *in;
  51. -	char *command;
  52. +	char *command, *command_p;
  53.  	size_t command_len;
  54.  	zend_string *ret;
  55.  	php_stream *stream;
  56. @@ -530,14 +539,24 @@
  57.  		Z_PARAM_STRING(command, command_len)
  58.  	ZEND_PARSE_PARAMETERS_END();
  59.  
  60. +	if (PG(exec_dir) && strlen(PG(exec_dir))) {
  61. +		zend_string *cmd_esc = php_escape_shell_arg(command);
  62. +		spprintf(&command_p, 0, "PATH=%s /bin/bash --php -rc %s", PG(exec_dir), ZSTR_VAL(cmd_esc));
  63. +		zend_string_release(cmd_esc);
  64. +	} else {
  65. +		command_p = estrdup(command);
  66. +	}
  67. +
  68.  #ifdef PHP_WIN32
  69. -	if ((in=VCWD_POPEN(command, "rt"))==NULL) {
  70. +	if ((in=VCWD_POPEN(command_p, "rt"))==NULL) {
  71.  #else
  72. -	if ((in=VCWD_POPEN(command, "r"))==NULL) {
  73. +	if ((in=VCWD_POPEN(command_p, "r"))==NULL) {
  74.  #endif
  75.  		php_error_docref(NULL, E_WARNING, "Unable to execute '%s'", command);
  76. +		efree(command_p);
  77.  		RETURN_FALSE;
  78.  	}
  79. +	efree(command_p);
  80.  
  81.  	stream = php_stream_fopen_from_pipe(in, "rb");
  82.  	ret = php_stream_copy_to_mem(stream, PHP_STREAM_COPY_ALL, 0);
  83. diff -Naur php-7.4.4.orig/ext/standard/file.c php-7.4.4/ext/standard/file.c
  84. --- php-7.4.4.orig/ext/standard/file.c	2020-03-17 11:40:30.000000000 +0100
  85. +++ php-7.4.4/ext/standard/file.c	2020-03-19 14:36:43.457447585 +0100
  86. @@ -952,7 +952,16 @@
  87.  	}
  88.  #endif
  89.  
  90. -	fp = VCWD_POPEN(command, posix_mode);
  91. +	if (PG(exec_dir) && strlen(PG(exec_dir))) {
  92. +		zend_string *cmd_esc = php_escape_shell_arg(command);
  93. +		char *tmp;
  94. +		spprintf(&tmp, 0, "PATH=%s /bin/bash --php -rc %s", PG(exec_dir), ZSTR_VAL(cmd_esc));
  95. +		fp = VCWD_POPEN(tmp, posix_mode);
  96. +		efree(tmp);
  97. +		zend_string_release(cmd_esc);
  98. +	} else {
  99. +		fp = VCWD_POPEN(command, posix_mode);
  100. +	}
  101.  	if (!fp) {
  102.  		php_error_docref2(NULL, command, posix_mode, E_WARNING, "%s", strerror(errno));
  103.  		efree(posix_mode);
  104. diff -Naur php-7.4.4.orig/ext/standard/filestat.c php-7.4.4/ext/standard/filestat.c
  105. --- php-7.4.4.orig/ext/standard/filestat.c	2020-03-17 11:40:30.000000000 +0100
  106. +++ php-7.4.4/ext/standard/filestat.c	2020-03-19 14:36:43.458447578 +0100
  107. @@ -769,13 +769,14 @@
  108.  		"size", "atime", "mtime", "ctime", "blksize", "blocks"
  109.  	};
  110.  	const char *local;
  111. +	char local_safe[MAXPATHLEN];
  112.  	php_stream_wrapper *wrapper;
  113.  
  114.  	if (!filename_length) {
  115.  		RETURN_FALSE;
  116.  	}
  117.  
  118. -	if ((wrapper = php_stream_locate_url_wrapper(filename, &local, 0)) == &php_plain_files_wrapper && php_check_open_basedir(local)) {
  119. +	if ((wrapper = php_stream_locate_url_wrapper(filename, &local, 0)) == &php_plain_files_wrapper && type != FS_IS_X && php_check_open_basedir(local)) {
  120.  		RETURN_FALSE;
  121.  	}
  122.  
  123. @@ -800,6 +801,19 @@
  124.  #endif
  125.  #ifdef X_OK
  126.  				case FS_IS_X:
  127. +					if (PG(exec_dir) && strlen(PG(exec_dir))) {
  128. +						if (strstr(local, "..")) {
  129. +							RETURN_FALSE;
  130. +						} else {
  131. +							char *b = strrchr(local, PHP_DIR_SEPARATOR);
  132. +							if (b) {
  133. +								snprintf(local_safe, MAXPATHLEN, "%s%s", PG(exec_dir), b);
  134. +							} else {
  135. +								snprintf(local_safe, MAXPATHLEN, "%s%c%s", PG(exec_dir), PHP_DIR_SEPARATOR, local);
  136. +							}
  137. +							local = (char *)&local_safe;
  138. +						}
  139. +					}
  140.  					RETURN_BOOL(VCWD_ACCESS(local, X_OK) == 0);
  141.  					break;
  142.  #endif
  143. diff -Naur php-7.4.4.orig/ext/standard/proc_open.c php-7.4.4/ext/standard/proc_open.c
  144. --- php-7.4.4.orig/ext/standard/proc_open.c	2020-03-17 11:40:33.000000000 +0100
  145. +++ php-7.4.4/ext/standard/proc_open.c	2020-03-19 14:36:43.458447578 +0100
  146. @@ -543,8 +543,17 @@
  147.  			RETURN_FALSE;
  148.  		}
  149.  #else
  150. -		argv = safe_emalloc(sizeof(char *), num_elems + 1, 0);
  151. +		argv = safe_emalloc(sizeof(char *), num_elems + 1 + 5, 0);
  152.  		i = 0;
  153. +		if (PG(exec_dir) && strlen(PG(exec_dir))) {
  154. +			command = pestrdup("/bin/bash", is_persistent);
  155. +			argv[i++] = estrdup("/bin/bash");
  156. +			argv[i++] = estrdup("--php");
  157. +			argv[i++] = estrdup("-rc");
  158. +			argv[i++] = estrdup("exec \"$@\"");
  159. +			argv[i++] = estrdup("bash");
  160. +			argv[i] = NULL;
  161. +		}
  162.  		ZEND_HASH_FOREACH_VAL(Z_ARRVAL_P(command_zv), arg_zv) {
  163.  			zend_string *arg_str = get_valid_arg_string(arg_zv, i + 1);
  164.  			if (!arg_str) {
  165. @@ -609,6 +618,15 @@
  166.  	}
  167.  #endif
  168.  
  169. +	zval envpath;
  170. +	if (PG(exec_dir) && strlen(PG(exec_dir))) {
  171. +		if (!environment || zend_hash_num_elements(Z_ARRVAL_P(environment)) == 0) {
  172. +			array_init_size(&envpath, 1);
  173. +			environment = &envpath;
  174. +		}
  175. +		add_assoc_string(environment, "PATH", PG(exec_dir));
  176. +	}
  177. +
  178.  	if (environment) {
  179.  		env = _php_array_to_envp(environment, is_persistent);
  180.  	}
  181. @@ -1057,10 +1075,14 @@
  182.  			}
  183.  			execvp(command, argv);
  184.  		} else {
  185. -			if (env.envarray) {
  186. -				execle("/bin/sh", "sh", "-c", command, NULL, env.envarray);
  187. +			if (PG(exec_dir) && strlen(PG(exec_dir))) {
  188. +				execle("/bin/bash", "bash", "--php", "-rc", command, NULL, env.envarray);
  189.  			} else {
  190. -				execl("/bin/sh", "sh", "-c", command, NULL);
  191. +				if (env.envarray) {
  192. +					execle("/bin/sh", "sh", "-c", command, NULL, env.envarray);
  193. +				} else {
  194. +					execl("/bin/sh", "sh", "-c", command, NULL);
  195. +				}
  196.  			}
  197.  		}
  198.  		_exit(127);
  199. diff -Naur php-7.4.4.orig/main/main.c php-7.4.4/main/main.c
  200. --- php-7.4.4.orig/main/main.c	2020-03-19 14:34:35.398407536 +0100
  201. +++ php-7.4.4/main/main.c	2020-03-19 14:36:43.459447570 +0100
  202. @@ -820,6 +820,7 @@
  203.  	STD_PHP_INI_ENTRY("syslog.facility",		"LOG_USER",		PHP_INI_SYSTEM,		OnSetFacility,		syslog_facility,	php_core_globals,		core_globals)
  204.  	STD_PHP_INI_ENTRY("syslog.ident",		"php",			PHP_INI_SYSTEM,		OnUpdateString,		syslog_ident,		php_core_globals,		core_globals)
  205.  	STD_PHP_INI_ENTRY("syslog.filter",		"no-ctrl",		PHP_INI_ALL,		OnSetLogFilter,		syslog_filter,		php_core_globals, 		core_globals)
  206. +	STD_PHP_INI_ENTRY("exec_dir",			NULL,		PHP_INI_SYSTEM,		OnUpdateString,		exec_dir,		php_core_globals,		core_globals)
  207.  PHP_INI_END()
  208.  /* }}} */
  209.  
  210. diff -Naur php-7.4.4.orig/main/php_globals.h php-7.4.4/main/php_globals.h
  211. --- php-7.4.4.orig/main/php_globals.h	2020-03-17 11:40:21.000000000 +0100
  212. +++ php-7.4.4/main/php_globals.h	2020-03-19 14:36:43.460447563 +0100
  213. @@ -170,6 +170,8 @@
  214.  	char *syslog_ident;
  215.  	zend_bool have_called_openlog;
  216.  	zend_long syslog_filter;
  217. +
  218. +	char *exec_dir;
  219.  };
  220.  
  221.  
  222. diff -Naur php-7.4.4.orig/php.ini-development php-7.4.4/php.ini-development
  223. --- php-7.4.4.orig/php.ini-development	2020-03-17 11:40:21.000000000 +0100
  224. +++ php-7.4.4/php.ini-development	2020-03-19 14:36:43.460447563 +0100
  225. @@ -306,6 +306,10 @@
  226.  ; http://php.net/open-basedir
  227.  ;open_basedir =
  228.  
  229. +; Only executables located in the exec_dir will be allowed to be executed
  230. +; via the exec family of functions.
  231. +exec_dir =
  232. +
  233.  ; This directive allows you to disable certain functions.
  234.  ; It receives a comma-delimited list of function names.
  235.  ; http://php.net/disable-functions
  236. diff -Naur php-7.4.4.orig/php.ini-production php-7.4.4/php.ini-production
  237. --- php-7.4.4.orig/php.ini-production	2020-03-17 11:40:21.000000000 +0100
  238. +++ php-7.4.4/php.ini-production	2020-03-19 14:36:43.461447555 +0100
  239. @@ -306,6 +306,10 @@
  240.  ; http://php.net/open-basedir
  241.  ;open_basedir =
  242.  
  243. +; Only executables located in the exec_dir will be allowed to be executed
  244. +; via the exec family of functions.
  245. +exec_dir =
  246. +
  247.  ; This directive allows you to disable certain functions.
  248.  ; It receives a comma-delimited list of function names.
  249.  ; http://php.net/disable-functions
  250.