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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 a/ext/standard/exec.c b/ext/standard/exec.c
  11. --- a/ext/standard/exec.c	2023-09-12 13:29:39.000000000 +0200
  12. +++ b/ext/standard/exec.c	2023-09-15 09:46:25.210504849 +0200
  13. @@ -116,21 +116,30 @@
  14.  	FILE *fp;
  15.  	char *buf;
  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. @@ -513,7 +522,7 @@
  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. @@ -531,14 +540,24 @@
  57.  		RETURN_THROWS();
  58.  	}
  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 a/ext/standard/file.c b/ext/standard/file.c
  84. --- a/ext/standard/file.c	2023-09-12 13:29:39.000000000 +0200
  85. +++ b/ext/standard/file.c	2023-09-15 09:46:25.211504841 +0200
  86. @@ -825,7 +825,16 @@
  87.  		RETURN_THROWS();
  88.  	}
  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 a/ext/standard/filestat.c b/ext/standard/filestat.c
  105. --- a/ext/standard/filestat.c	2023-09-12 13:29:39.000000000 +0200
  106. +++ b/ext/standard/filestat.c	2023-09-15 09:46:25.211504841 +0200
  107. @@ -710,6 +710,7 @@
  108.  	zend_stat_t *stat_sb = &ssb.sb;
  109.  	int flags = 0, rmask=S_IROTH, wmask=S_IWOTH, xmask=S_IXOTH; /* access rights defaults to other */
  110.  	const char *local = NULL;
  111. +	char local_safe[MAXPATHLEN];
  112.  	php_stream_wrapper *wrapper = NULL;
  113.  
  114.  	if (IS_ACCESS_CHECK(type)) {
  115. @@ -721,7 +722,7 @@
  116.  		}
  117.  
  118.  		if ((wrapper = php_stream_locate_url_wrapper(ZSTR_VAL(filename), &local, 0)) == &php_plain_files_wrapper
  119. -				&& php_check_open_basedir(local)) {
  120. +				&& type != FS_IS_X && php_check_open_basedir(local)) {
  121.  			RETURN_FALSE;
  122.  		}
  123.  
  124. @@ -752,9 +753,25 @@
  125.  					break;
  126.  #endif
  127.  #ifdef X_OK
  128. -				case FS_IS_X:
  129. -					RETURN_BOOL(VCWD_ACCESS(file_path_to_check, X_OK) == 0);
  130. +				case FS_IS_X: {
  131. +					bool xok = (VCWD_ACCESS(file_path_to_check, X_OK) == 0);
  132. +					if (!xok && PG(exec_dir) && strlen(PG(exec_dir))) {
  133. +						if (strstr(file_path_to_check, "..")) {
  134. +							RETURN_FALSE;
  135. +						} else {
  136. +							char *b = strrchr(file_path_to_check, PHP_DIR_SEPARATOR);
  137. +							if (b) {
  138. +								snprintf(local_safe, MAXPATHLEN, "%s%s", PG(exec_dir), b);
  139. +							} else {
  140. +								snprintf(local_safe, MAXPATHLEN, "%s%c%s", PG(exec_dir), PHP_DIR_SEPARATOR, file_path_to_check);
  141. +							}
  142. +							file_path_to_check = (char *)&local_safe;
  143. +						}
  144. +						xok = (VCWD_ACCESS(file_path_to_check, X_OK) == 0);
  145. +					}
  146. +					RETURN_BOOL(xok);
  147.  					break;
  148. +				}
  149.  #endif
  150.  			}
  151.  		}
  152. diff -Naur a/ext/standard/proc_open.c b/ext/standard/proc_open.c
  153. --- a/ext/standard/proc_open.c	2023-09-12 13:29:39.000000000 +0200
  154. +++ b/ext/standard/proc_open.c	2023-09-15 09:46:25.212504833 +0200
  155. @@ -664,7 +664,17 @@
  156.  	zend_string *command = NULL;
  157.  	int i = 0;
  158.  
  159. -	*argv = safe_emalloc(sizeof(char *), num_elems + 1, 0);
  160. +	*argv = safe_emalloc(sizeof(char *), num_elems + 1 + 5, 0);
  161. +
  162. +	if (PG(exec_dir) && strlen(PG(exec_dir))) {
  163. +		command = zend_string_init("/bin/bash", sizeof("/bin/bash") - 1, 0);
  164. +		(*argv)[i++] = estrdup("/bin/bash");
  165. +		(*argv)[i++] = estrdup("--php");
  166. +		(*argv)[i++] = estrdup("-rc");
  167. +		(*argv)[i++] = estrdup("exec \"$@\"");
  168. +		(*argv)[i++] = estrdup("bash");
  169. +		(*argv)[i] = NULL;
  170. +	}
  171.  
  172.  	ZEND_HASH_FOREACH_VAL(array, arg_zv) {
  173.  		zend_string *arg_str = get_valid_arg_string(arg_zv, i + 1);
  174. @@ -1158,6 +1168,15 @@
  175.  	}
  176.  #endif
  177.  
  178. +	zval envpath;
  179. +	if (PG(exec_dir) && strlen(PG(exec_dir))) {
  180. +		if (!environment || zend_hash_num_elements(Z_ARRVAL_P(environment)) == 0) {
  181. +			array_init_size(&envpath, 1);
  182. +			environment = &envpath;
  183. +		}
  184. +		add_assoc_string(environment, "PATH", PG(exec_dir));
  185. +	}
  186. +
  187.  	if (environment) {
  188.  		env = _php_array_to_envp(environment);
  189.  	}
  190. @@ -1315,10 +1334,14 @@
  191.  			}
  192.  			execvp(ZSTR_VAL(command_str), argv);
  193.  		} else {
  194. -			if (env.envarray) {
  195. -				execle("/bin/sh", "sh", "-c", ZSTR_VAL(command_str), NULL, env.envarray);
  196. +			if (PG(exec_dir) && strlen(PG(exec_dir))) {
  197. +				execle("/bin/bash", "bash", "--php", "-rc", ZSTR_VAL(command_str), NULL, env.envarray);
  198.  			} else {
  199. -				execl("/bin/sh", "sh", "-c", ZSTR_VAL(command_str), NULL);
  200. +				if (env.envarray) {
  201. +					execle("/bin/sh", "sh", "-c", ZSTR_VAL(command_str), NULL, env.envarray);
  202. +				} else {
  203. +					execl("/bin/sh", "sh", "-c", ZSTR_VAL(command_str), NULL);
  204. +				}
  205.  			}
  206.  		}
  207.  
  208. diff -Naur a/main/main.c b/main/main.c
  209. --- a/main/main.c	2023-09-12 13:29:39.000000000 +0200
  210. +++ b/main/main.c	2023-09-15 09:46:25.213504825 +0200
  211. @@ -777,6 +777,7 @@
  212.  	STD_PHP_INI_ENTRY("syslog.facility",		"LOG_USER",		PHP_INI_SYSTEM,		OnSetFacility,		syslog_facility,	php_core_globals,		core_globals)
  213.  	STD_PHP_INI_ENTRY("syslog.ident",		"php",			PHP_INI_SYSTEM,		OnUpdateString,		syslog_ident,		php_core_globals,		core_globals)
  214.  	STD_PHP_INI_ENTRY("syslog.filter",		"no-ctrl",		PHP_INI_ALL,		OnSetLogFilter,		syslog_filter,		php_core_globals, 		core_globals)
  215. +	STD_PHP_INI_ENTRY("exec_dir",			NULL,		PHP_INI_SYSTEM,		OnUpdateString,		exec_dir,		php_core_globals,		core_globals)
  216.  PHP_INI_END()
  217.  /* }}} */
  218.  
  219. diff -Naur a/main/php_globals.h b/main/php_globals.h
  220. --- a/main/php_globals.h	2023-09-12 13:29:39.000000000 +0200
  221. +++ b/main/php_globals.h	2023-09-15 09:46:25.213504825 +0200
  222. @@ -172,6 +172,8 @@
  223.  	char *syslog_ident;
  224.  	zend_long syslog_filter;
  225.  	zend_long error_log_mode;
  226. +
  227. +	char *exec_dir;
  228.  };
  229.  
  230.  
  231. diff -Naur a/php.ini-development b/php.ini-development
  232. --- a/php.ini-development	2023-09-12 13:29:39.000000000 +0200
  233. +++ b/php.ini-development	2023-09-15 09:46:25.213504825 +0200
  234. @@ -327,6 +327,10 @@
  235.  ; https://php.net/open-basedir
  236.  ;open_basedir =
  237.  
  238. +; Only executables located in the exec_dir will be allowed to be executed
  239. +; via the exec family of functions.
  240. +exec_dir =
  241. +
  242.  ; This directive allows you to disable certain functions.
  243.  ; It receives a comma-delimited list of function names.
  244.  ; https://php.net/disable-functions
  245. diff -Naur a/php.ini-production b/php.ini-production
  246. --- a/php.ini-production	2023-09-12 13:29:39.000000000 +0200
  247. +++ b/php.ini-production	2023-09-15 09:46:25.214504817 +0200
  248. @@ -327,6 +327,10 @@
  249.  ; https://php.net/open-basedir
  250.  ;open_basedir =
  251.  
  252. +; Only executables located in the exec_dir will be allowed to be executed
  253. +; via the exec family of functions.
  254. +exec_dir =
  255. +
  256.  ; This directive allows you to disable certain functions.
  257.  ; It receives a comma-delimited list of function names.
  258.  ; https://php.net/disable-functions
  259.