2009-12-30 Rodrigo Kumpera <rkumpera@novell.com>

[mono.git] / mono / mini / declsec.c

/*
 * declsec.c:  Declarative Security support
 *
 * Author:
 *      Sebastien Pouliot  <sebastien@ximian.com>
 *
 * Copyright (C) 2004-2005 Novell, Inc (http://www.novell.com)
 */

#include "declsec.h"
#include "mini.h"

/*
 * Does the methods (or it's class) as any declarative security attribute ?
 * Is so are they applicable ? (e.g. static class constructor)
 */
MonoBoolean
mono_method_has_declsec (MonoMethod *method)
{
        mono_jit_stats.cas_declsec_check++;

        if (method->wrapper_type == MONO_WRAPPER_MANAGED_TO_NATIVE || method->wrapper_type == MONO_WRAPPER_MANAGED_TO_MANAGED) {
                method = mono_marshal_method_from_wrapper (method);
                if (!method)
                        return FALSE;
        } else if (method->wrapper_type != MONO_WRAPPER_NONE)
                return FALSE;

        if ((method->klass->flags & TYPE_ATTRIBUTE_HAS_SECURITY) || (method->flags & METHOD_ATTRIBUTE_HAS_SECURITY)) {
                /* ignore static constructors */
                if (strcmp (method->name, ".cctor"))
                        return TRUE;
        }
        return FALSE;
}


/*
 * Fill actions for the specific index (which may either be an encoded class token or
 * an encoded method token) from the metadata image.
 * Returns TRUE if some actions requiring code generation are present, FALSE otherwise.
 */
void
mono_declsec_cache_stack_modifiers (MonoJitInfo *jinfo)
{
        /* first find the stack modifiers applied to the method */
        guint32 flags = mono_declsec_flags_from_method (jinfo->method);
        jinfo->cas_method_assert = (flags & MONO_DECLSEC_FLAG_ASSERT) != 0;
        jinfo->cas_method_deny = (flags & MONO_DECLSEC_FLAG_DENY) != 0;
        jinfo->cas_method_permitonly = (flags & MONO_DECLSEC_FLAG_PERMITONLY) != 0;

        /* then find the stack modifiers applied to the class */
        flags = mono_declsec_flags_from_class (jinfo->method->klass);
        jinfo->cas_class_assert = (flags & MONO_DECLSEC_FLAG_ASSERT) != 0;
        jinfo->cas_class_deny = (flags & MONO_DECLSEC_FLAG_DENY) != 0;
        jinfo->cas_class_permitonly = (flags & MONO_DECLSEC_FLAG_PERMITONLY) != 0;
}


MonoSecurityFrame*
mono_declsec_create_frame (MonoDomain *domain, MonoJitInfo *jinfo)
{
        MonoSecurityFrame *frame = (MonoSecurityFrame*) mono_object_new (domain, mono_defaults.runtimesecurityframe_class);

        if (!jinfo->cas_inited) {
                if (mono_method_has_declsec (jinfo->method)) {
                        /* Cache the stack modifiers into the MonoJitInfo structure to speed up future stack walks */
                        mono_declsec_cache_stack_modifiers (jinfo);
                }
                jinfo->cas_inited = TRUE;
        }

        MONO_OBJECT_SETREF (frame, method, mono_method_get_object (domain, jinfo->method, NULL));
        MONO_OBJECT_SETREF (frame, domain, domain->domain);

        /* stack modifiers on methods have priority on (i.e. replaces) modifiers on class */

        if (jinfo->cas_method_assert) {
                mono_declsec_get_method_action (jinfo->method, SECURITY_ACTION_ASSERT, &frame->assert);
        } else if (jinfo->cas_class_assert) {
                mono_declsec_get_class_action (jinfo->method->klass, SECURITY_ACTION_ASSERT, &frame->assert);
        }

        if (jinfo->cas_method_deny) {
                mono_declsec_get_method_action (jinfo->method, SECURITY_ACTION_DENY, &frame->deny);
        } else if (jinfo->cas_class_deny) {
                mono_declsec_get_class_action (jinfo->method->klass, SECURITY_ACTION_DENY, &frame->deny);
        }

        if (jinfo->cas_method_permitonly) {
                mono_declsec_get_method_action (jinfo->method, SECURITY_ACTION_PERMITONLY, &frame->permitonly);
        } else if (jinfo->cas_class_permitonly) {
                mono_declsec_get_class_action (jinfo->method->klass, SECURITY_ACTION_PERMITONLY, &frame->permitonly);
        }

        /* g_warning ("FRAME %s A(%p,%d) D(%p,%d) PO(%p,%d)", 
        jinfo->method->name, frame->assert.blob, frame->assert.size, frame->deny.blob, frame->deny.size, frame->permitonly.blob,frame->permitonly.size); */

        return frame;
}


/*
 * Execute any LinkDemand, NonCasLinkDemand, LinkDemandChoice declarative
 * security attribute present on the called method or it's class.
 *
 * @domain      The current application domain
 * @caller      The method calling
 * @callee      The called method.
 * return value: TRUE if a security violation is detection, FALSE otherwise.
 *
 * Note: The execution is done in managed code in SecurityManager.LinkDemand
 */
static gboolean
mono_declsec_linkdemand_standard (MonoDomain *domain, MonoMethod *caller, MonoMethod *callee)
{
        MonoDeclSecurityActions linkclass, linkmethod;

        mono_jit_stats.cas_linkdemand++;

        if (mono_declsec_get_linkdemands (callee, &linkclass, &linkmethod)) {
                MonoAssembly *assembly = mono_image_get_assembly (caller->klass->image);
                MonoReflectionAssembly *refass = (MonoReflectionAssembly*) mono_assembly_get_object (domain, assembly);
                MonoSecurityManager *secman = mono_security_manager_get_methods ();
                MonoObject *res;
                gpointer args [3];

                args [0] = refass;
                args [1] = &linkclass;
                args [2] = &linkmethod;

                res = mono_runtime_invoke (secman->linkdemand, NULL, args, NULL);
                return !(*(MonoBoolean *) mono_object_unbox(res));
        }
        return FALSE;
}

/*
 * Ensure that the restrictions for partially trusted code are satisfied.
 *
 * @domain      The current application domain
 * @assembly    The assembly to query
 * return value: TRUE if the assembly is runnning at FullTrust, FALSE otherwise.
 */
static gboolean
mono_declsec_is_assembly_fulltrust (MonoDomain *domain, MonoAssembly *assembly)
{
        if (!MONO_SECMAN_FLAG_INIT (assembly->fulltrust)) {
                MonoReflectionAssembly *refass = (MonoReflectionAssembly*) mono_assembly_get_object (domain, assembly);
                MonoSecurityManager *secman = mono_security_manager_get_methods ();

                if (secman && refass) {
                        MonoObject *res;
                        gpointer args [1];
                        args [0] = refass;

                        res = mono_runtime_invoke (secman->linkdemandfulltrust, NULL, args, NULL);
                        if (*(MonoBoolean *) mono_object_unbox(res)) {
                                /* keep this value cached as it will be used very often */
                                MONO_SECMAN_FLAG_SET_VALUE (assembly->fulltrust, TRUE);
                                return TRUE;
                        }
                }

                MONO_SECMAN_FLAG_SET_VALUE (assembly->fulltrust, FALSE);
                return FALSE;
        }

        return MONO_SECMAN_FLAG_GET_VALUE (assembly->fulltrust);
}

/*
 * Ensure that the restrictions for partially trusted code are satisfied.
 *
 * @domain      The current application domain
 * @caller      The method calling
 * @callee      The called method
 * return value: TRUE if a security violation is detected, FALSE otherwise.
 *
 * If callee's assembly is strongnamed and doesn't have an 
 * [AllowPartiallyTrustedCallers] attribute then we must enforce a LinkDemand
 * for FullTrust on all public/protected methods on public class.
 *
 * Note: APTC is only effective on stongnamed assemblies.
 */
static gboolean
mono_declsec_linkdemand_aptc (MonoDomain *domain, MonoMethod *caller, MonoMethod *callee)
{
        MonoSecurityManager* secman = NULL;
        MonoAssembly *assembly;
        guint32 size = 0;

        mono_jit_stats.cas_linkdemand_aptc++;

        /* A - Applicable only if we're calling into *another* assembly */
        if (caller->klass->image == callee->klass->image)
                return FALSE;

        /* B - Applicable if we're calling a public/protected method from a public class */
        if (!(callee->klass->flags & TYPE_ATTRIBUTE_PUBLIC) || !(callee->flags & FIELD_ATTRIBUTE_PUBLIC))
                return FALSE;

        /* C - Applicable if the callee's assembly is strongnamed */
        if ((mono_image_get_public_key (callee->klass->image, &size) == NULL) || (size < MONO_ECMA_KEY_LENGTH))
                return FALSE;

        /* D - the callee's assembly must have [AllowPartiallyTrustedCallers] */
        assembly = mono_image_get_assembly (callee->klass->image);
        if (!MONO_SECMAN_FLAG_INIT (assembly->aptc)) {
                MonoCustomAttrInfo* cinfo = mono_custom_attrs_from_assembly (assembly);
                gboolean result = FALSE;
                secman = mono_security_manager_get_methods ();
                if (secman && cinfo) {
                        /* look for AllowPartiallyTrustedCallersAttribute */
                        result = mono_custom_attrs_has_attr (cinfo, secman->allowpartiallytrustedcallers);
                }
                if (cinfo)
                        mono_custom_attrs_free (cinfo);
                MONO_SECMAN_FLAG_SET_VALUE (assembly->aptc, result);
        }

        if (MONO_SECMAN_FLAG_GET_VALUE (assembly->aptc))
                return FALSE;

        /* E - the caller's assembly must have full trust permissions */
        assembly = mono_image_get_assembly (caller->klass->image);
        if (mono_declsec_is_assembly_fulltrust (domain, assembly))
                return FALSE;

        /* g_warning ("FAILURE *** JIT LinkDemand APTC check *** %s.%s calls into %s.%s",
                caller->klass->name, caller->name, callee->klass->name, callee->name); */

        return TRUE;    /* i.e. throw new SecurityException(); */
}

/*
 * Ensure that the restrictions for calling native code are satisfied.
 *
 * @domain      The current application domain
 * @caller      The method calling
 * @native      The native method called
 * return value: TRUE if a security violation is detected, FALSE otherwise.
 *
 * Executing Platform Invokes (P/Invoke) is a is a restricted operation.
 * The security policy must allow (SecurityPermissionFlag.UnmanagedCode)
 * an assembly to do this.
 *
 * This LinkDemand case is special because it only needs to call managed
 * code once per assembly. Further calls on this assembly will use a cached
 * flag for better performance. This is not done before the first call (e.g.
 * when loading the assembly) because that would break the lazy policy
 * evaluation that Mono use (another time saving optimization).
 *
 * Note: P/Invoke checks are ALWAYS (1) done at JIT time (as a LinkDemand). 
 * They are also checked at runtime, using a Demand (stack walk), unless the 
 * method or it's class has a [SuppressUnmanagedCodeSecurity] attribute.
 *
 * (1) well as long as the security manager is active (i.e. --security)
 */
static gboolean
mono_declsec_linkdemand_pinvoke (MonoDomain *domain, MonoMethod *caller, MonoMethod *native)
{
        MonoAssembly *assembly = mono_image_get_assembly (caller->klass->image);

        mono_jit_stats.cas_linkdemand_pinvoke++;

        /* Check for P/Invoke flag for the assembly */
        if (!MONO_SECMAN_FLAG_INIT (assembly->unmanaged)) {
                /* Check if we know (and have) or FullTrust status */
                if (MONO_SECMAN_FLAG_INIT (assembly->fulltrust) && MONO_SECMAN_FLAG_GET_VALUE (assembly->fulltrust)) {
                        /* FullTrust includes UnmanagedCode permission */
                        MONO_SECMAN_FLAG_SET_VALUE (assembly->unmanaged, TRUE);
                        return FALSE;
                } else {
                        MonoReflectionAssembly *refass = (MonoReflectionAssembly*) mono_assembly_get_object (domain, assembly);
                        MonoSecurityManager* secman = mono_security_manager_get_methods ();
                        if (secman && refass) {
                                MonoObject *res;
                                gpointer args [1];
                                args [0] = refass;

                                res = mono_runtime_invoke (secman->linkdemandunmanaged, NULL, args, NULL);
                                if (*(MonoBoolean *) mono_object_unbox(res)) {
                                        MONO_SECMAN_FLAG_SET_VALUE (assembly->unmanaged, TRUE);
                                        return FALSE;
                                }
                        }
                }

                MONO_SECMAN_FLAG_SET_VALUE (assembly->unmanaged, FALSE);
        }

        if (MONO_SECMAN_FLAG_GET_VALUE (assembly->unmanaged))
                return FALSE;

        /* g_warning ("FAILURE *** JIT LinkDemand P/Invoke check *** %s.%s calls into %s.%s",
                caller->klass->name, caller->name, native->klass->name, native->name); */

        return TRUE;    /* i.e. throw new SecurityException(); */
}

/*
 * Ensure that the restrictions for calling internal calls are satisfied.
 *
 * @domain      The current application domain
 * @caller      The method calling
 * @icall       The internal call method
 * return value: TRUE if a security violation is detected, FALSE otherwise.
 *
 * We can't trust the icall flags/iflags as it comes from the assembly
 * that we may want to restrict and we do not have the public/restricted
 * information about icalls in the runtime. Actually it is not so bad 
 * as the CLR 2.0 doesn't enforce that restriction anymore.
 * 
 * So we'll limit the icalls to originate from ECMA signed assemblies 
 * (as this is required for partial trust scenarios) - or - assemblies that 
 * have FullTrust.
 */
static gboolean
mono_declsec_linkdemand_icall (MonoDomain *domain, MonoMethod *caller, MonoMethod *icall)
{
        MonoAssembly *assembly;

        mono_jit_stats.cas_linkdemand_icall++;

        /* check if the _icall_ is defined inside an ECMA signed assembly */
        assembly = mono_image_get_assembly (icall->klass->image);
        if (!MONO_SECMAN_FLAG_INIT (assembly->ecma)) {
                guint32 size = 0;
                const char *pk = mono_image_get_public_key (icall->klass->image, &size);
                MONO_SECMAN_FLAG_SET_VALUE (assembly->ecma, mono_is_ecma_key (pk, size));
        }

        if (MONO_SECMAN_FLAG_GET_VALUE (assembly->ecma))
                return FALSE;

        /* else check if the _calling_ assembly is running at FullTrust */
        assembly = mono_image_get_assembly (caller->klass->image);
        return !mono_declsec_is_assembly_fulltrust (domain, assembly);
}


/*
 * Before the JIT can link (call) into a method the following security checks
 * must be done:
 *
 * We check that the code has the permission to link when:
 * 1. the code try to call an internal call;
 * 2. the code try to p/invoke to unmanaged code;
 * 3. the code try to call trusted code without being trusted itself -
 *    or without the trusted code permission (APTC);
 * 4. the code try to call managed code protected by a LinkDemand security 
 *    attribute
 *
 * Failures result in a SecurityException being thrown (later in mini code).
 *
 * Note: Some checks are duplicated in managed code to deal when reflection is
 * used to call the methods.
 */
guint32
mono_declsec_linkdemand (MonoDomain *domain, MonoMethod *caller, MonoMethod *callee)
{
        guint32 violation = MONO_JIT_SECURITY_OK;

        /* short-circuit corlib as it is fully trusted (within itself)
         * and because this cause major recursion headaches */
        if ((caller->klass->image == mono_defaults.corlib) && (callee->klass->image == mono_defaults.corlib))
                return violation;

        /* next, the special (implied) linkdemand */

        if (callee->iflags & METHOD_IMPL_ATTRIBUTE_INTERNAL_CALL) {
                /* restrict internal calls into the runtime */
                if (mono_declsec_linkdemand_icall (domain, caller, callee))
                        violation = MONO_JIT_LINKDEMAND_ECMA;
        } else if (callee->flags & METHOD_ATTRIBUTE_PINVOKE_IMPL) {
                /* CAS can restrict p/invoke calls with the assembly granted permissions */
                if (mono_declsec_linkdemand_pinvoke (domain, caller, callee))
                        violation = MONO_JIT_LINKDEMAND_PINVOKE;
        }

        if (!violation) {
                /* check if we allow partially trusted callers in trusted (signed) assemblies */
                if (mono_declsec_linkdemand_aptc (domain, caller, callee))
                        violation = MONO_JIT_LINKDEMAND_APTC;
        }

        /* then the "normal" LinkDemand (only when called method has declarative security) */
        if (!violation && mono_method_has_declsec (callee)) {
                /* LinkDemand are ignored for static constructors (ensured by calling mono_method_has_declsec) */
                if (mono_declsec_linkdemand_standard (domain, caller, callee))
                        violation = MONO_JIT_LINKDEMAND_PERMISSION;
        }

        /* if (violation) g_warning ("mono_declsec_linkdemand violation reported %d", violation); */
        return violation;
}