Add the complement to the putenv() security

NEWS

@@ -2,8 +2,8 @@ PHP 4.0                                                                    NEWS
 |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 
 ?? ?? ????, Version 4.0 Beta 4
-- Added the ability to prevent the user from overriding certain environment
-  variables in Safe Mode (Zeev)
+- Added the ability to control the environment variables the user is allowed
+  to change in Safe Mode, using INI directives (Zeev)
 - Fixed a crash bug in strtr() working on large input strings (Zeev)
 - Ora_GetColumn()/Ora_FetchInto() now return NULL for NULL-Columns. (Thies)
 - OCI8 now supports binding of NULL-values. Module cleanups. (Thies)

ext/standard/basic_functions.c

@@ -314,11 +314,11 @@ static PHP_INI_MH(OnUpdateSafeModeProtectedEnvVars)
 	BLS_FETCH();
 
 	protected_vars = estrndup(new_value, new_value_length);
-	zend_hash_clean(&BG(protected_env_vars));
+	zend_hash_clean(&BG(sm_protected_env_vars));
 
 	protected_var=strtok(protected_vars, ", ");
 	while (protected_var) {
-		zend_hash_update(&BG(protected_env_vars), protected_var, strlen(protected_var), &dummy, sizeof(int), NULL);
+		zend_hash_update(&BG(sm_protected_env_vars), protected_var, strlen(protected_var), &dummy, sizeof(int), NULL);
 		protected_var=strtok(NULL, ", ");
 	}
 	efree(protected_vars);
@@ -326,8 +326,21 @@ static PHP_INI_MH(OnUpdateSafeModeProtectedEnvVars)
 }
 
 
+static PHP_INI_MH(OnUpdateSafeModeAllowedEnvVars)
+{
+	BLS_FETCH();
+
+	if (BG(sm_allowed_env_vars)) {
+		free(BG(sm_allowed_env_vars));
+	}
+	BG(sm_allowed_env_vars) = zend_strndup(new_value, new_value_length);
+	return SUCCESS;
+}
+
+
 PHP_INI_BEGIN()
-	PHP_INI_ENTRY_EX("safe_mode_protected_env_vars",	SAFE_MODE_PROTECTED_ENV_VARS,	PHP_INI_SYSTEM,		OnUpdateSafeModeProtectedEnvVars,		NULL)
+	PHP_INI_ENTRY_EX("safe_mode_sm_protected_env_vars",	SAFE_MODE_PROTECTED_ENV_VARS,	PHP_INI_SYSTEM,		OnUpdateSafeModeProtectedEnvVars,		NULL)
+	PHP_INI_ENTRY_EX("safe_mode_allowed_env_vars",		SAFE_MODE_ALLOWED_ENV_VARS,		PHP_INI_SYSTEM,		OnUpdateSafeModeAllowedEnvVars,			NULL)
 PHP_INI_END()
 
 
@@ -377,12 +390,16 @@ static void basic_globals_ctor(BLS_D)
 {
 	BG(next) = NULL;
 	BG(left) = -1;
-	zend_hash_init(&BG(protected_env_vars), 5, NULL, NULL, 1);
+	zend_hash_init(&BG(sm_protected_env_vars), 5, NULL, NULL, 1);
+	BG(sm_allowed_env_vars) = NULL;
 }
 
 static void basic_globals_dtor(BLS_D)
 {
-	zend_hash_destroy(&BG(protected_env_vars));
+	zend_hash_destroy(&BG(sm_protected_env_vars));
+	if (BG(sm_allowed_env_vars)) {
+		free(BG(sm_allowed_env_vars));
+	}
 }
 
 
@@ -536,7 +553,7 @@ PHP_FUNCTION(putenv)
 		PLS_FETCH();
 		
 		if (PG(safe_mode)) {
-			/* check the protected_env_vars table */
+			/* check the sm_protected_env_vars table */
 		}
 
 		pe.putenv_string = estrndup((*str)->value.str.val,(*str)->value.str.len);
@@ -547,12 +564,36 @@ PHP_FUNCTION(putenv)
 		pe.key_len = strlen(pe.key);
 		pe.key = estrndup(pe.key,pe.key_len);
 		
-		if (PG(safe_mode)
-			&& zend_hash_exists(&BG(protected_env_vars), pe.key, pe.key_len)) {
-			php_error(E_WARNING, "Safe Mode:  Cannot override protected environment variable '%s'", pe.key);
-			efree(pe.putenv_string);
-			efree(pe.key);
-			RETURN_FALSE;
+		if (PG(safe_mode)) {
+			/* Check the protected list */
+			if (zend_hash_exists(&BG(sm_protected_env_vars), pe.key, pe.key_len)) {
+				php_error(E_WARNING, "Safe Mode:  Cannot override protected environment variable '%s'", pe.key);
+				efree(pe.putenv_string);
+				efree(pe.key);
+				RETURN_FALSE;
+			}
+
+			/* Check the allowed list */
+			if (BG(sm_allowed_env_vars) && *BG(sm_allowed_env_vars)) {
+				char *allowed_env_vars = estrdup(BG(sm_allowed_env_vars));
+				char *allowed_prefix = strtok(allowed_env_vars, ", ");
+				zend_bool allowed=0;
+
+				while (allowed_prefix) {
+					if (!strncmp(allowed_prefix, pe.key, strlen(allowed_prefix))) {
+						allowed=1;
+						break;
+					}
+					allowed_prefix = strtok(NULL, ", ");
+				}
+				efree(allowed_env_vars);
+				if (!allowed) {
+					php_error(E_WARNING, "Safe Mode:  Cannot set environment variable '%s' - it's not in the allowed list", pe.key);
+					efree(pe.putenv_string);
+					efree(pe.key);
+					RETURN_FALSE;
+				}
+			}
 		}
 
 		zend_hash_del(&BG(putenv_ht),pe.key,pe.key_len+1);

ext/standard/basic_functions.h

@@ -136,7 +136,8 @@ typedef struct {
 	zval **array_walk_func_name;
 	zval **user_compare_func_name;
 	
-	HashTable protected_env_vars;
+	HashTable sm_protected_env_vars;
+	char *sm_allowed_env_vars;
 
 	/* pageinfo.c */
 	long page_uid;
@@ -184,6 +185,7 @@ typedef struct {
 
 /* Values are comma-delimited
  */
-#define SAFE_MODE_PROTECTED_ENV_VARS "LD_LIBRARY_PATH"
+#define SAFE_MODE_PROTECTED_ENV_VARS	"LD_LIBRARY_PATH"
+#define SAFE_MODE_ALLOWED_ENV_VARS		"PHP_"
 
 #endif /* _BASIC_FUNCTIONS_H */

php.ini-dist

@@ -77,12 +77,26 @@ allow_call_time_pass_reference	= On	; whether to enable the ability to force arg
 ; Safe Mode
 safe_mode		=	Off
 safe_mode_exec_dir	=
-safe_mode_protected_env_vars = LD_LIBRARY_PATH		; In Safe Mode, setting certain environment
-													; variables may be a potential security
-													; breach.  This directive contains
-													; a comma delimited list of environment
-													; variables, that the end user won't be
-													; able to override using putenv()
+safe_mode_allowed_env_vars = PHP_					; Setting certain environment variables
+													; may be a potential security breach.
+													; This directive contains a comma-delimited
+													; list of prefixes.  In Safe Mode, the
+													; user may only alter environment
+													; variables whose names begin with the
+													; prefixes supplied here.
+													; By default, users will only be able
+													; to set environment variables that begin
+													; with PHP_ (e.g. PHP_FOO=BAR).
+													; Note:  If this directive is empty, PHP
+													; will let the user modify ANY environment
+													; variable!
+safe_mode_protected_env_vars = LD_LIBRARY_PATH		; This directive contains a comma-
+													; delimited list of environment variables,
+													; that the end user won't be able to
+													; change using putenv().
+													; These variables will be protected
+													; even if safe_mode_allowed_env_vars is
+													; set to allow to change them.
 
 ; Colors for Syntax Highlighting mode.  Anything that's acceptable in <font color=???> would work.
 highlight.string	=	#DD0000