[v2,5/5] libsepol: more strict validation

Commit Message

Christian Göttsche July 21, 2022, 3:24 p.m. UTC

Validate that

  - each constraint has at least one expression
  - classes reference a valid common class identifier
  - the role flavor is either ROLE or ATTRIB
  - types reference a valid primary identifier
  - types refer to a raw type, not an attribute, as bounds
  - extended permissions in avtabs have a valid specifier
  - type av rules refer to a raw type (e.g. type_transition)
  - conditionals have at least one expression
  - the state and flags of conditionals are valid
  - filename transitions have at least one datum
  - low ports are not bigger than high ones in port ocontexts
  - genfs declarations refer to a valid class identifier
  - genfs declarations contains a filesystem name
  - filename transitions refer to a raw type
  - permissive types are raw ones
  - the range transition hashmap is valid
  - the type-attribute-maps are valid

Signed-off-by: Christian Göttsche <[e-mail]>
---
v2:
   only validate type_attr maps for policies since version 20
---
 libsepol/src/policydb_validate.c | 259 +++++++++++++++++++++++++------
 1 file changed, 209 insertions(+), 50 deletions(-)

Patch

diff --git a/libsepol/src/policydb_validate.c b/libsepol/src/policydb_validate.c
index 0f399771..521ea4ff 100644
--- a/libsepol/src/policydb_validate.c
+++ b/libsepol/src/policydb_validate.c
@@ -48,6 +48,8 @@  static int validate_init(validate_t *flavor, char **val_to_name, uint32_t nprim)
 
 static int validate_array_init(const policydb_t *p, validate_t flavors[])
 {
+	if (validate_init(&flavors[SYM_COMMONS], p->p_common_val_to_name, p->p_commons.nprim))
+		goto bad;
 	if (validate_init(&flavors[SYM_CLASSES], p->p_class_val_to_name, p->p_classes.nprim))
 		goto bad;
 	if (validate_init(&flavors[SYM_ROLES], p->p_role_val_to_name, p->p_roles.nprim))
@@ -235,6 +237,9 @@  static int validate_constraint_nodes(sepol_handle_t *handle, unsigned int nperms
 		if (nperms > 0 && nperms != PERM_SYMTAB_SIZE && cons->permissions >= (UINT32_C(1) << nperms))
 			goto bad;
 
+		if (!cons->expr)
+			goto bad;
+
 		for (cexp = cons->expr; cexp; cexp = cexp->next) {
 			if (cexp->expr_type == CEXPR_NAMES) {
 				if (cexp->attr & CEXPR_XTARGET && nperms != 0)
@@ -339,10 +344,33 @@  bad:
 	return -1;
 }
 
+static int validate_common_datum(sepol_handle_t *handle, const common_datum_t *common, validate_t flavors[])
+{
+	if (validate_value(common->s.value, &flavors[SYM_COMMONS]))
+		goto bad;
+	if (common->permissions.nprim > PERM_SYMTAB_SIZE)
+		goto bad;
+
+	return 0;
+
+bad:
+	ERR(handle, "Invalid common class datum");
+	return -1;
+}
+
+static int validate_common_datum_wrapper(__attribute__((unused)) hashtab_key_t k, hashtab_datum_t d, void *args)
+{
+	map_arg_t *margs = args;
+
+	return validate_common_datum(margs->handle, d, margs->flavors);
+}
+
 static int validate_class_datum(sepol_handle_t *handle, const class_datum_t *class, validate_t flavors[])
 {
 	if (validate_value(class->s.value, &flavors[SYM_CLASSES]))
 		goto bad;
+	if (class->comdatum && validate_common_datum(handle, class->comdatum, flavors))
+		goto bad;
 	if (class->permissions.nprim > PERM_SYMTAB_SIZE)
 		goto bad;
 	if (validate_constraint_nodes(handle, class->permissions.nprim, class->constraints, flavors))
@@ -405,25 +433,6 @@  static int validate_class_datum_wrapper(__attribute__((unused)) hashtab_key_t k,
 	return validate_class_datum(margs->handle, d, margs->flavors);
 }
 
-static int validate_common_datum(sepol_handle_t *handle, const common_datum_t *common)
-{
-	if (common->permissions.nprim > PERM_SYMTAB_SIZE)
-		goto bad;
-
-	return 0;
-
-bad:
-	ERR(handle, "Invalid common class datum");
-	return -1;
-}
-
-static int validate_common_datum_wrapper(__attribute__((unused)) hashtab_key_t k, hashtab_datum_t d, void *args)
-{
-	map_arg_t *margs = args;
-
-	return validate_common_datum(margs->handle, d);
-}
-
 static int validate_role_datum(sepol_handle_t *handle, const role_datum_t *role, validate_t flavors[])
 {
 	if (validate_value(role->s.value, &flavors[SYM_ROLES]))
@@ -437,6 +446,14 @@  static int validate_role_datum(sepol_handle_t *handle, const role_datum_t *role,
 	if (validate_ebitmap(&role->roles, &flavors[SYM_ROLES]))
 		goto bad;
 
+	switch(role->flavor) {
+	case ROLE_ROLE:
+	case ROLE_ATTRIB:
+		break;
+	default:
+		goto bad;
+	}
+
 	return 0;
 
 bad:
@@ -451,19 +468,46 @@  static int validate_role_datum_wrapper(__attribute__((unused)) hashtab_key_t k,
 	return validate_role_datum(margs->handle, d, margs->flavors);
 }
 
-static int validate_type_datum(sepol_handle_t *handle, const type_datum_t *type, validate_t flavors[])
+static int validate_simpletype(uint32_t value, const policydb_t *p, validate_t flavors[])
 {
-	if (validate_value(type->s.value, &flavors[SYM_TYPES]))
+	const type_datum_t *type;
+
+	if (validate_value(value, &flavors[SYM_TYPES]))
+		goto bad;
+
+	type = p->type_val_to_struct[value - 1];
+	if (!type)
 		goto bad;
-	if (validate_ebitmap(&type->types, &flavors[SYM_TYPES]))
+
+	if (type->flavor == TYPE_ATTRIB)
+		goto bad;
+
+	return 0;
+
+bad:
+	return -1;
+}
+
+static int validate_type_datum(sepol_handle_t *handle, const type_datum_t *type, const policydb_t *p, validate_t flavors[])
+{
+	if (validate_value(type->s.value, &flavors[SYM_TYPES]))
 		goto bad;
-	if (type->bounds && validate_value(type->bounds, &flavors[SYM_TYPES]))
+	if (type->primary && validate_value(type->primary, &flavors[SYM_TYPES]))
 		goto bad;
 
 	switch (type->flavor) {
 	case TYPE_TYPE:
-	case TYPE_ATTRIB:
 	case TYPE_ALIAS:
+		if (!ebitmap_is_empty(&type->types))
+			goto bad;
+		if (type->bounds && validate_simpletype(type->bounds, p, flavors))
+			goto bad;
+		break;
+	case TYPE_ATTRIB:
+		if (validate_ebitmap(&type->types, &flavors[SYM_TYPES]))
+			goto bad;
+		if (type->bounds)
+			goto bad;
 		break;
 	default:
 		goto bad;
@@ -491,7 +535,7 @@  static int validate_type_datum_wrapper(__attribute__((unused)) hashtab_key_t k,
 {
 	map_arg_t *margs = args;
 
-	return validate_type_datum(margs->handle, d, margs->flavors);
+	return validate_type_datum(margs->handle, d, margs->policy, margs->flavors);
 }
 
 static int validate_mls_semantic_cat(const mls_semantic_cat_t *cat, const validate_t *cats)
@@ -758,22 +802,42 @@  bad:
 	return -1;
 }
 
+static int validate_xperms(const avtab_extended_perms_t *xperms)
+{
+	switch (xperms->specified) {
+	case AVTAB_XPERMS_IOCTLDRIVER:
+	case AVTAB_XPERMS_IOCTLFUNCTION:
+		break;
+	default:
+		goto bad;
+	}
+
+	return 0;
+
+bad:
+	return -1;
+}
 static int validate_avtab_key_and_datum(avtab_key_t *k, avtab_datum_t *d, void *args)
 {
-	validate_t *flavors = (validate_t *)args;
+	map_arg_t *margs = args;
+
+	if (validate_avtab_key(k, 0, margs->flavors))
+		return -1;
 
-	if (validate_avtab_key(k, 0, flavors))
+	if ((k->specified & AVTAB_TYPE) && validate_simpletype(d->data, margs->policy, margs->flavors))
 		return -1;
 
-	if ((k->specified & AVTAB_TYPE) && validate_value(d->data, &flavors[SYM_TYPES]))
+	if ((k->specified & AVTAB_XPERMS) && validate_xperms(d->xperms))
 		return -1;
 
 	return 0;
 }
 
-static int validate_avtab(sepol_handle_t *handle, const avtab_t *avtab, validate_t flavors[])
+static int validate_avtab(sepol_handle_t *handle, const avtab_t *avtab, const policydb_t *p, validate_t flavors[])
 {
-	if (avtab_map(avtab, validate_avtab_key_and_datum, flavors)) {
+	map_arg_t margs = { flavors, handle, p };
+
+	if (avtab_map(avtab, validate_avtab_key_and_datum, &margs)) {
 		ERR(handle, "Invalid avtab");
 		return -1;
 	}
@@ -797,20 +861,15 @@  static int validate_cond_av_list(sepol_handle_t *handle, const cond_av_list_t *c
 	return 0;
 }
 
-static int validate_avrules(sepol_handle_t *handle, const avrule_t *avrule, int conditional, validate_t flavors[])
+static int validate_avrules(sepol_handle_t *handle, const avrule_t *avrule, int conditional, const policydb_t *p, validate_t flavors[])
 {
-	const class_perm_node_t *class;
+	const class_perm_node_t *classperm;
 
 	for (; avrule; avrule = avrule->next) {
 		if (validate_type_set(&avrule->stypes, &flavors[SYM_TYPES]))
 			goto bad;
 		if (validate_type_set(&avrule->ttypes, &flavors[SYM_TYPES]))
 			goto bad;
-		class = avrule->perms;
-		for (; class; class = class->next) {
-			if (validate_value(class->tclass, &flavors[SYM_CLASSES]))
-				goto bad;
-		}
 
 		switch(avrule->specified) {
 		case AVRULE_ALLOWED:
@@ -833,6 +892,13 @@  static int validate_avrules(sepol_handle_t *handle, const avrule_t *avrule, int
 			goto bad;
 		}
 
+		for (classperm = avrule->perms; classperm; classperm = classperm->next) {
+			if (validate_value(classperm->tclass, &flavors[SYM_CLASSES]))
+				goto bad;
+			if ((avrule->specified & AVRULE_TYPE) && validate_simpletype(classperm->data, p, flavors))
+				goto bad;
+		}
+
 		if (avrule->specified & AVRULE_XPERMS) {
 			if (!avrule->xperms)
 				goto bad;
@@ -885,6 +951,9 @@  static int validate_cond_expr(sepol_handle_t *handle, const struct cond_expr *ex
 {
 	int depth = -1;
 
+	if (!expr)
+		goto bad;
+
 	for (; expr; expr = expr->next) {
 		switch(expr->expr_type) {
 		case COND_BOOL:
@@ -922,7 +991,7 @@  bad:
 	return -1;
 }
 
-static int validate_cond_list(sepol_handle_t *handle, const cond_list_t *cond, validate_t flavors[])
+static int validate_cond_list(sepol_handle_t *handle, const cond_list_t *cond, const policydb_t *p, validate_t flavors[])
 {
 	for (; cond; cond = cond->next) {
 		if (validate_cond_expr(handle, cond->expr, &flavors[SYM_BOOLS]))
@@ -931,12 +1000,28 @@  static int validate_cond_list(sepol_handle_t *handle, const cond_list_t *cond, v
 			goto bad;
 		if (validate_cond_av_list(handle, cond->false_list, flavors))
 			goto bad;
-		if (validate_avrules(handle, cond->avtrue_list, 1, flavors))
+		if (validate_avrules(handle, cond->avtrue_list, 1, p, flavors))
 			goto bad;
-		if (validate_avrules(handle, cond->avfalse_list, 1, flavors))
+		if (validate_avrules(handle, cond->avfalse_list, 1, p, flavors))
 			goto bad;
 		if (validate_bool_id_array(handle, cond->bool_ids, cond->nbools, &flavors[SYM_BOOLS]))
 			goto bad;
+
+		switch (cond->cur_state) {
+		case 0:
+		case 1:
+			break;
+		default:
+			goto bad;
+		}
+
+		switch (cond->flags) {
+		case 0:
+		case COND_NODE_FLAGS_TUNABLE:
+			break;
+		default:
+			goto bad;
+		}
 	}
 
 	return 0;
@@ -992,6 +1077,8 @@  static int validate_filename_trans(hashtab_key_t k, hashtab_datum_t d, void *arg
 		goto bad;
 	if (validate_value(ftk->tclass, &flavors[SYM_CLASSES]))
 		goto bad;
+	if (!ftd)
+		goto bad;
 	for (; ftd; ftd = ftd->next) {
 		if (validate_ebitmap(&ftd->stypes, &flavors[SYM_TYPES]))
 			goto bad;
@@ -1046,6 +1133,10 @@  static int validate_ocontexts(sepol_handle_t *handle, const policydb_t *p, valid
 					if (validate_context(&octx->context[1], flavors, p->mls))
 						goto bad;
 					break;
+				case OCON_PORT:
+					if (octx->u.port.low_port > octx->u.port.high_port)
+						goto bad;
+					break;
 				case OCON_FSUSE:
 					switch (octx->v.behavior) {
 					case SECURITY_FS_USE_XATTR:
@@ -1076,7 +1167,12 @@  static int validate_genfs(sepol_handle_t *handle, const policydb_t *p, validate_
 		for (octx = genfs->head; octx; octx = octx->next) {
 			if (validate_context(&octx->context[0], flavors, p->mls))
 				goto bad;
+			if (octx->v.sclass && validate_value(octx->v.sclass, &flavors[SYM_CLASSES]))
+				goto bad;
 		}
+
+		if (!genfs->fstype)
+			goto bad;
 	}
 
 	return 0;
@@ -1173,7 +1269,7 @@  bad:
 }
 
 
-static int validate_filename_trans_rules(sepol_handle_t *handle, const filename_trans_rule_t *filename_trans, validate_t flavors[])
+static int validate_filename_trans_rules(sepol_handle_t *handle, const filename_trans_rule_t *filename_trans, const policydb_t *p, validate_t flavors[])
 {
 	for (; filename_trans; filename_trans = filename_trans->next) {
 		if (validate_type_set(&filename_trans->stypes, &flavors[SYM_TYPES]))
@@ -1182,7 +1278,7 @@  static int validate_filename_trans_rules(sepol_handle_t *handle, const filename_
 			goto bad;
 		if (validate_value(filename_trans->tclass,&flavors[SYM_CLASSES] ))
 			goto bad;
-		if (validate_value(filename_trans->otype, &flavors[SYM_TYPES]))
+		if (validate_simpletype(filename_trans->otype, p, flavors))
 			goto bad;
 
 		/* currently only the RULE_SELF flag can be set */
@@ -1211,15 +1307,15 @@  static int validate_symtabs(sepol_handle_t *handle, const symtab_t symtabs[], va
 	return 0;
 }
 
-static int validate_avrule_blocks(sepol_handle_t *handle, const avrule_block_t *avrule_block, validate_t flavors[])
+static int validate_avrule_blocks(sepol_handle_t *handle, const avrule_block_t *avrule_block, const policydb_t *p, validate_t flavors[])
 {
 	const avrule_decl_t *decl;
 
 	for (; avrule_block; avrule_block = avrule_block->next) {
 		for (decl = avrule_block->branch_list; decl != NULL; decl = decl->next) {
-			if (validate_cond_list(handle, decl->cond_list, flavors))
+			if (validate_cond_list(handle, decl->cond_list, p, flavors))
 				goto bad;
-			if (validate_avrules(handle, decl->avrules, 0, flavors))
+			if (validate_avrules(handle, decl->avrules, 0, p, flavors))
 				goto bad;
 			if (validate_role_trans_rules(handle, decl->role_tr_rules, flavors))
 				goto bad;
@@ -1231,7 +1327,7 @@  static int validate_avrule_blocks(sepol_handle_t *handle, const avrule_block_t *
 				goto bad;
 			if (validate_scope_index(handle, &decl->declared, flavors))
 				goto bad;
-			if (validate_filename_trans_rules(handle, decl->filename_trans_rules, flavors))
+			if (validate_filename_trans_rules(handle, decl->filename_trans_rules, p, flavors))
 				goto bad;
 			if (validate_symtabs(handle, decl->symtab, flavors))
 				goto bad;
@@ -1259,7 +1355,7 @@  static int validate_permissives(sepol_handle_t *handle, const policydb_t *p, val
 	unsigned i;
 
 	ebitmap_for_each_positive_bit(&p->permissive_map, node, i) {
-		if (validate_value(i, &flavors[SYM_TYPES]))
+		if (validate_simpletype(i, p, flavors))
 			goto bad;
 	}
 
@@ -1270,6 +1366,61 @@  bad:
 	return -1;
 }
 
+static int validate_range_transition(hashtab_key_t key, hashtab_datum_t data, void *args)
+{
+	const range_trans_t *rt = (const range_trans_t *)key;
+	const mls_range_t *r = data;
+	const map_arg_t *margs = args;
+	const validate_t *flavors = margs->flavors;
+
+	if (validate_value(rt->source_type, &flavors[SYM_TYPES]))
+		goto bad;
+	if (validate_value(rt->target_type, &flavors[SYM_TYPES]))
+		goto bad;
+	if (validate_value(rt->target_class, &flavors[SYM_CLASSES]))
+		goto bad;
+
+	if (validate_mls_range(r, &flavors[SYM_LEVELS], &flavors[SYM_CATS]))
+		goto bad;
+
+	return 0;
+
+bad:
+	return -1;
+}
+
+static int validate_range_transitions(sepol_handle_t *handle, const policydb_t *p, validate_t flavors[])
+{
+	map_arg_t margs = { flavors, handle, p };
+
+	if (hashtab_map(p->range_tr, validate_range_transition, &margs)) {
+		ERR(handle, "Invalid range transition");
+			return -1;
+	}
+
+	return 0;
+}
+
+static int validate_typeattr_map(sepol_handle_t *handle, const policydb_t *p, validate_t flavors[])
+{
+	const ebitmap_t *maps = p->type_attr_map;
+	unsigned int i;
+
+	if (p->policy_type == POLICY_KERN) {
+		for (i = 0; i < p->p_types.nprim; i++) {
+			if (validate_ebitmap(&maps[i], &flavors[SYM_TYPES]))
+				goto bad;
+		}
+	} else if (maps)
+		goto bad;
+
+	return 0;
+
+bad:
+	ERR(handle, "Invalid type attr map");
+	return -1;
+}
+
 static int validate_properties(sepol_handle_t *handle, const policydb_t *p)
 {
 	switch (p->policy_type) {
@@ -1341,10 +1492,10 @@  int policydb_validate(sepol_handle_t *handle, const policydb_t *p)
 		goto bad;
 
 	if (p->policy_type == POLICY_KERN) {
-		if (validate_avtab(handle, &p->te_avtab, flavors))
+		if (validate_avtab(handle, &p->te_avtab, p, flavors))
 			goto bad;
 		if (p->policyvers >= POLICYDB_VERSION_BOOL)
-			if (validate_cond_list(handle, p->cond_list, flavors))
+			if (validate_cond_list(handle, p->cond_list, p, flavors))
 				goto bad;
 		if (validate_role_transes(handle, p->role_tr, flavors))
 			goto bad;
@@ -1354,7 +1505,7 @@  int policydb_validate(sepol_handle_t *handle, const policydb_t *p)
 			if (validate_filename_trans_hashtab(handle, p->filename_trans, flavors))
 				goto bad;
 	} else {
-		if (validate_avrule_blocks(handle, p->global, flavors))
+		if (validate_avrule_blocks(handle, p->global, p, flavors))
 			goto bad;
 	}
 
@@ -1376,6 +1527,14 @@  int policydb_validate(sepol_handle_t *handle, const policydb_t *p)
 	if (validate_permissives(handle, p, flavors))
 		goto bad;
 
+	if (validate_range_transitions(handle, p, flavors))
+		goto bad;
+
+	if (p->policyvers >= POLICYDB_VERSION_AVTAB) {
+		if (validate_typeattr_map(handle, p, flavors))
+			goto bad;
+	}
+
 	validate_array_destroy(flavors);
 
 	return 0;