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security-core-clr.c
591 lines (520 loc) · 19.6 KB
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security-core-clr.c
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/*
* security-core-clr.c: CoreCLR security
*
* Authors:
* Mark Probst <mark.probst@gmail.com>
* Sebastien Pouliot <sebastien@ximian.com>
*
* Copyright 2007-2009 Novell, Inc (http://www.novell.com)
*/
#include <mono/metadata/class-internals.h>
#include <mono/metadata/security-manager.h>
#include <mono/metadata/assembly.h>
#include <mono/metadata/appdomain.h>
#include <mono/metadata/verify-internals.h>
#include <mono/metadata/object.h>
#include <mono/metadata/exception.h>
#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;
/* unlike most Invoke* cases InvokeMember is not inside System.Reflection[.Emit] but is SecuritySafeCritical */
if (((*kname == 'T') && (strcmp (kname, "Type") == 0)) ||
((*kname == 'M') && (strcmp (kname, "MonoType")) == 0)) {
/* if calling InvokeMember then we can't stop the stackwalk here and need to look at the caller */
if (strcmp (m->name, "InvokeMember") == 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) it will 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_can_access_internals
*
* Check if we allow [InternalsVisibleTo] to work between two images.
*/
gboolean
mono_security_core_clr_can_access_internals (MonoImage *accessing, MonoImage* accessed)
{
/* are we trying to access internals of a platform assembly ? if not this is acceptable */
if (!mono_security_core_clr_is_platform_image (accessed))
return TRUE;
/* we can't let everyone with the right name and public key token access the internals of platform code.
* (Silverlight can rely on the strongname signature of the assemblies, but Mono does not verify them)
* However platform code is fully trusted so it can access the internals of other platform code assemblies */
if (mono_security_core_clr_is_platform_image (accessing))
return TRUE;
/* catch-22: System.Xml needs access to mscorlib's internals (e.g. ArrayList) but is not considered platform code.
* Promoting it to platform code would create another issue since (both Mono/Moonlight or MS version of)
* System.Xml.Linq.dll (an SDK, not platform, assembly) needs access to System.Xml.dll internals (either ).
* The solution is to trust, even transparent code, in the plugin directory to access platform code internals */
if (!accessed->assembly->basedir || !accessing->assembly->basedir)
return FALSE;
return (strcmp (accessed->assembly->basedir, accessing->assembly->basedir) == 0);
}
/*
* 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 TRUE for current corlib (minimum
* trust-able subset) otherwise return FALSE. Any real CoreCLR host
* should provide its own callback to define platform code (i.e.
* this default is meant for test only).
*/
static gboolean
default_platform_check (const char *image_name)
{
if (mono_defaults.corlib) {
return (strcmp (mono_defaults.corlib->name, image_name) == 0);
} else {
/* this can get called even before we load corlib (e.g. the EXE itself) */
const char *corlib = "mscorlib.dll";
int ilen = strlen (image_name);
int clen = strlen (corlib);
return ((ilen >= clen) && (strcmp ("mscorlib.dll", image_name + ilen - clen) == 0));
}
}
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;
}