/* * security-core-clr.c: CoreCLR security * * Authors: * Mark Probst * Sebastien Pouliot * * Copyright 2007-2009 Novell, Inc (http://www.novell.com) */ #include #include #include #include #include #include #include #include "security-core-clr.h" gboolean mono_security_core_clr_test = FALSE; static MonoClass* security_critical_attribute (void) { static MonoClass *class = NULL; if (!class) { class = mono_class_from_name (mono_defaults.corlib, "System.Security", "SecurityCriticalAttribute"); } g_assert (class); return class; } static MonoClass* security_safe_critical_attribute (void) { static MonoClass *class = NULL; if (!class) { class = mono_class_from_name (mono_defaults.corlib, "System.Security", "SecuritySafeCriticalAttribute"); } g_assert (class); return class; } /* * mono_security_core_clr_check_inheritance: * * Determine if the specified class can inherit from its parent using * the CoreCLR inheritance rules. * * Base Type Allow Derived Type * ------------ ------------------ * Transparent Transparent, SafeCritical, Critical * SafeCritical SafeCritical, Critical * Critical Critical * * Reference: http://msdn.microsoft.com/en-us/magazine/cc765416.aspx#id0190030 */ void mono_security_core_clr_check_inheritance (MonoClass *class) { MonoSecurityCoreCLRLevel class_level, parent_level; MonoClass *parent = class->parent; if (!parent) return; class_level = mono_security_core_clr_class_level (class); parent_level = mono_security_core_clr_class_level (parent); if (class_level < parent_level) mono_class_set_failure (class, MONO_EXCEPTION_TYPE_LOAD, NULL); } /* * mono_security_core_clr_check_override: * * Determine if the specified override can "legally" override the * specified base method using the CoreCLR inheritance rules. * * Base (virtual/interface) Allowed override * ------------------------ ------------------------- * Transparent Transparent, SafeCritical * SafeCritical Transparent, SafeCritical * Critical Critical * * Reference: http://msdn.microsoft.com/en-us/magazine/cc765416.aspx#id0190030 */ void mono_security_core_clr_check_override (MonoClass *class, MonoMethod *override, MonoMethod *base) { MonoSecurityCoreCLRLevel base_level = mono_security_core_clr_method_level (base, FALSE); MonoSecurityCoreCLRLevel override_level = mono_security_core_clr_method_level (override, FALSE); /* if the base method is decorated with [SecurityCritical] then the overrided method MUST be too */ if (base_level == MONO_SECURITY_CORE_CLR_CRITICAL) { if (override_level != MONO_SECURITY_CORE_CLR_CRITICAL) mono_class_set_failure (class, MONO_EXCEPTION_TYPE_LOAD, NULL); } else { /* base is [SecuritySafeCritical] or [SecurityTransparent], override MUST NOT be [SecurityCritical] */ if (override_level == MONO_SECURITY_CORE_CLR_CRITICAL) mono_class_set_failure (class, MONO_EXCEPTION_TYPE_LOAD, NULL); } } /* * get_caller_no_reflection_related: * * Find the first managed caller that is either: * (a) located outside the platform code assemblies; or * (b) not related to reflection and delegates * * Returns TRUE to stop the stackwalk, FALSE to continue to the next frame. */ static gboolean get_caller_no_reflection_related (MonoMethod *m, gint32 no, gint32 ilo, gboolean managed, gpointer data) { MonoMethod **dest = data; const char *ns; /* skip unmanaged frames */ if (!managed) return FALSE; if (m->wrapper_type != MONO_WRAPPER_NONE) return FALSE; /* quick out (any namespace not starting with an 'S' */ ns = m->klass->name_space; if (!ns || (*ns != 'S')) { *dest = m; return TRUE; } /* stop if the method is not part of platform code */ if (!mono_security_core_clr_is_platform_image (m->klass->image)) { *dest = m; return TRUE; } /* any number of calls inside System.Reflection are allowed */ if (strcmp (ns, "System.Reflection") == 0) return FALSE; /* any number of calls inside System.Reflection are allowed */ if (strcmp (ns, "System.Reflection.Emit") == 0) return FALSE; /* calls from System.Delegate are also possible and allowed */ if (strcmp (ns, "System") == 0) { const char *kname = m->klass->name; if ((*kname == 'A') && (strcmp (kname, "Activator") == 0)) return FALSE; // the security check on the delegate is made at creation time, not at invoke time if (((*kname == 'D') && (strcmp (kname, "Delegate") == 0)) || ((*kname == 'M') && (strcmp (kname, "MulticastDelegate")) == 0)) { // if we're invoking then we can stop our stack walk if (strcmp (m->name, "DynamicInvoke") != 0) return FALSE; } } if (m == *dest) { *dest = NULL; return FALSE; } *dest = m; return TRUE; } /* * get_reflection_caller: * * Walk to the first managed method outside: * - System.Reflection* namespaces * - System.[MulticastDelegate]Delegate or Activator type * - platform code * and return a pointer to its MonoMethod. * * This is required since CoreCLR checks needs to be done on this "real" caller. */ static MonoMethod* get_reflection_caller (void) { MonoMethod *m = NULL; mono_stack_walk_no_il (get_caller_no_reflection_related, &m); if (!m) g_warning ("could not find a caller outside reflection"); return m; } /* * check_field_access: * * Return TRUE if the caller method can access the specified field, FALSE otherwise. */ static gboolean check_field_access (MonoMethod *caller, MonoClassField *field) { /* if get_reflection_caller returns NULL then we assume the caller has NO privilege */ if (caller) { MonoClass *klass = (mono_field_get_flags (field) & FIELD_ATTRIBUTE_STATIC) ? NULL : mono_field_get_parent (field); return mono_method_can_access_field_full (caller, field, klass); } return FALSE; } /* * check_method_access: * * Return TRUE if the caller method can access the specified callee method, FALSE otherwise. */ static gboolean check_method_access (MonoMethod *caller, MonoMethod *callee) { /* if get_reflection_caller returns NULL then we assume the caller has NO privilege */ if (caller) { MonoClass *klass = (callee->flags & METHOD_ATTRIBUTE_STATIC) ? NULL : callee->klass; return mono_method_can_access_method_full (caller, callee, klass); } return FALSE; } /* * mono_security_core_clr_ensure_reflection_access_field: * * Ensure that the specified field can be used with reflection since * Transparent code cannot access to Critical fields and can only use * them if they are visible from it's point of view. * * A FieldAccessException is thrown if the field is cannot be accessed. */ void mono_security_core_clr_ensure_reflection_access_field (MonoClassField *field) { MonoMethod *caller = get_reflection_caller (); /* CoreCLR restrictions applies to Transparent code/caller */ if (mono_security_core_clr_method_level (caller, TRUE) != MONO_SECURITY_CORE_CLR_TRANSPARENT) return; /* Transparent code cannot [get|set]value on Critical fields */ if (mono_security_core_clr_class_level (mono_field_get_parent (field)) == MONO_SECURITY_CORE_CLR_CRITICAL) mono_raise_exception (mono_get_exception_field_access ()); /* also it cannot access a fields that is not visible from it's (caller) point of view */ if (!check_field_access (caller, field)) mono_raise_exception (mono_get_exception_field_access ()); } /* * mono_security_core_clr_ensure_reflection_access_method: * * Ensure that the specified method can be used with reflection since * Transparent code cannot call Critical methods and can only call them * if they are visible from it's point of view. * * A MethodAccessException is thrown if the field is cannot be accessed. */ void mono_security_core_clr_ensure_reflection_access_method (MonoMethod *method) { MonoMethod *caller = get_reflection_caller (); /* CoreCLR restrictions applies to Transparent code/caller */ if (mono_security_core_clr_method_level (caller, TRUE) != MONO_SECURITY_CORE_CLR_TRANSPARENT) return; /* Transparent code cannot invoke, even using reflection, Critical code */ if (mono_security_core_clr_method_level (method, TRUE) == MONO_SECURITY_CORE_CLR_CRITICAL) mono_raise_exception (mono_get_exception_method_access ()); /* also it cannot invoke a method that is not visible from it's (caller) point of view */ if (!check_method_access (caller, method)) mono_raise_exception (mono_get_exception_method_access ()); } /* * can_avoid_corlib_reflection_delegate_optimization: * * Mono's mscorlib use delegates to optimize PropertyInfo and EventInfo * reflection calls. This requires either a bunch of additional, and not * really required, [SecuritySafeCritical] in the class libraries or * (like this) a way to skip them. As a bonus we also avoid the stack * walk to find the caller. * * Return TRUE if we can skip this "internal" delegate creation, FALSE * otherwise. */ static gboolean can_avoid_corlib_reflection_delegate_optimization (MonoMethod *method) { if (!mono_security_core_clr_is_platform_image (method->klass->image)) return FALSE; if (strcmp (method->klass->name_space, "System.Reflection") != 0) return FALSE; if (strcmp (method->klass->name, "MonoProperty") == 0) { if ((strcmp (method->name, "GetterAdapterFrame") == 0) || strcmp (method->name, "StaticGetterAdapterFrame") == 0) return TRUE; } else if (strcmp (method->klass->name, "EventInfo") == 0) { if ((strcmp (method->name, "AddEventFrame") == 0) || strcmp (method->name, "StaticAddEventAdapterFrame") == 0) return TRUE; } return FALSE; } /* * mono_security_core_clr_ensure_delegate_creation: * * Return TRUE if a delegate can be created on the specified method. * CoreCLR also affect the binding, so throwOnBindFailure must be * FALSE to let this function return (FALSE) normally, otherwise (if * throwOnBindFailure is TRUE) itwill throw an ArgumentException. * * A MethodAccessException is thrown if the specified method is not * visible from the caller point of view. */ gboolean mono_security_core_clr_ensure_delegate_creation (MonoMethod *method, gboolean throwOnBindFailure) { MonoMethod *caller; /* note: mscorlib creates delegates to avoid reflection (optimization), we ignore those cases */ if (can_avoid_corlib_reflection_delegate_optimization (method)) return TRUE; caller = get_reflection_caller (); /* if the "real" caller is not Transparent then it do can anything */ if (mono_security_core_clr_method_level (caller, TRUE) != MONO_SECURITY_CORE_CLR_TRANSPARENT) return TRUE; /* otherwise it (as a Transparent caller) cannot create a delegate on a Critical method... */ if (mono_security_core_clr_method_level (method, TRUE) == MONO_SECURITY_CORE_CLR_CRITICAL) { /* but this throws only if 'throwOnBindFailure' is TRUE */ if (!throwOnBindFailure) return FALSE; mono_raise_exception (mono_get_exception_argument ("method", "Transparent code cannot call Critical code")); } /* also it cannot create the delegate on a method that is not visible from it's (caller) point of view */ if (!check_method_access (caller, method)) mono_raise_exception (mono_get_exception_method_access ()); return TRUE; } /* * mono_security_core_clr_ensure_dynamic_method_resolved_object: * * Called from mono_reflection_create_dynamic_method (reflection.c) to add some extra checks required for CoreCLR. * Dynamic methods needs to check to see if the objects being used (e.g. methods, fields) comes from platform code * and do an accessibility check in this case. Otherwise (i.e. user/application code) can be used without this extra * accessbility check. */ MonoException* mono_security_core_clr_ensure_dynamic_method_resolved_object (gpointer ref, MonoClass *handle_class) { /* XXX find/create test cases for other handle_class XXX */ if (handle_class == mono_defaults.fieldhandle_class) { MonoClassField *field = (MonoClassField*) ref; MonoClass *klass = mono_field_get_parent (field); /* fields coming from platform code have extra protection (accessibility check) */ if (mono_security_core_clr_is_platform_image (klass->image)) { MonoMethod *caller = get_reflection_caller (); /* XXX Critical code probably can do this / need some test cases (safer off otherwise) XXX */ if (!check_field_access (caller, field)) return mono_get_exception_field_access (); } } else if (handle_class == mono_defaults.methodhandle_class) { MonoMethod *method = (MonoMethod*) ref; /* methods coming from platform code have extra protection (accessibility check) */ if (mono_security_core_clr_is_platform_image (method->klass->image)) { MonoMethod *caller = get_reflection_caller (); /* XXX Critical code probably can do this / need some test cases (safer off otherwise) XXX */ if (!check_method_access (caller, method)) return mono_get_exception_method_access (); } } return NULL; } /* * mono_security_core_clr_level_from_cinfo: * * Return the MonoSecurityCoreCLRLevel that match the attribute located * in the specified custom attributes. If no attribute is present it * defaults to MONO_SECURITY_CORE_CLR_TRANSPARENT, which is the default * level for all code under the CoreCLR. */ static MonoSecurityCoreCLRLevel mono_security_core_clr_level_from_cinfo (MonoCustomAttrInfo *cinfo, MonoImage *image) { int level = MONO_SECURITY_CORE_CLR_TRANSPARENT; if (cinfo && mono_custom_attrs_has_attr (cinfo, security_safe_critical_attribute ())) level = MONO_SECURITY_CORE_CLR_SAFE_CRITICAL; if (cinfo && mono_custom_attrs_has_attr (cinfo, security_critical_attribute ())) level = MONO_SECURITY_CORE_CLR_CRITICAL; return level; } /* * mono_security_core_clr_class_level_no_platform_check: * * Return the MonoSecurityCoreCLRLevel for the specified class, without * checking for platform code. This help us avoid multiple redundant * checks, e.g. * - a check for the method and one for the class; * - a check for the class and outer class(es) ... */ static MonoSecurityCoreCLRLevel mono_security_core_clr_class_level_no_platform_check (MonoClass *class) { MonoSecurityCoreCLRLevel level = MONO_SECURITY_CORE_CLR_TRANSPARENT; MonoCustomAttrInfo *cinfo = mono_custom_attrs_from_class (class); if (cinfo) { level = mono_security_core_clr_level_from_cinfo (cinfo, class->image); mono_custom_attrs_free (cinfo); } if (level == MONO_SECURITY_CORE_CLR_TRANSPARENT && class->nested_in) level = mono_security_core_clr_class_level_no_platform_check (class->nested_in); return level; } /* * mono_security_core_clr_class_level: * * Return the MonoSecurityCoreCLRLevel for the specified class. */ MonoSecurityCoreCLRLevel mono_security_core_clr_class_level (MonoClass *class) { /* non-platform code is always Transparent - whatever the attributes says */ if (!mono_security_core_clr_test && !mono_security_core_clr_is_platform_image (class->image)) return MONO_SECURITY_CORE_CLR_TRANSPARENT; return mono_security_core_clr_class_level_no_platform_check (class); } /* * mono_security_core_clr_method_level: * * Return the MonoSecurityCoreCLRLevel for the specified method. * If with_class_level is TRUE then the type (class) will also be * checked, otherwise this will only report the information about * the method itself. */ MonoSecurityCoreCLRLevel mono_security_core_clr_method_level (MonoMethod *method, gboolean with_class_level) { MonoCustomAttrInfo *cinfo; MonoSecurityCoreCLRLevel level = MONO_SECURITY_CORE_CLR_TRANSPARENT; /* if get_reflection_caller returns NULL then we assume the caller has NO privilege */ if (!method) return level; /* non-platform code is always Transparent - whatever the attributes says */ if (!mono_security_core_clr_test && !mono_security_core_clr_is_platform_image (method->klass->image)) return level; cinfo = mono_custom_attrs_from_method (method); if (cinfo) { level = mono_security_core_clr_level_from_cinfo (cinfo, method->klass->image); mono_custom_attrs_free (cinfo); } if (with_class_level && level == MONO_SECURITY_CORE_CLR_TRANSPARENT) level = mono_security_core_clr_class_level (method->klass); return level; } /* * mono_security_core_clr_is_platform_image: * * Return the (cached) boolean value indicating if this image represent platform code */ gboolean mono_security_core_clr_is_platform_image (MonoImage *image) { return image->core_clr_platform_code; } /* * default_platform_check: * * Default platform check. Always return FALSE. */ static gboolean default_platform_check (const char *image_name) { return FALSE; } static MonoCoreClrPlatformCB platform_callback = default_platform_check; /* * mono_security_core_clr_determine_platform_image: * * Call the supplied callback (from mono_security_set_core_clr_platform_callback) * to determine if this image represents platform code. */ gboolean mono_security_core_clr_determine_platform_image (MonoImage *image) { return platform_callback (image->name); } /* * mono_security_enable_core_clr: * * Enable the verifier and the CoreCLR security model */ void mono_security_enable_core_clr () { mono_verifier_set_mode (MONO_VERIFIER_MODE_VERIFIABLE); mono_security_set_mode (MONO_SECURITY_MODE_CORE_CLR); } /* * mono_security_set_core_clr_platform_callback: * * Set the callback function that will be used to determine if an image * is part, or not, of the platform code. */ void mono_security_set_core_clr_platform_callback (MonoCoreClrPlatformCB callback) { platform_callback = callback; }