[PATCH] checkpolicy: error out if required permission would exceed limit

["Christian Göttsche" <cgzones@googlemail.com>]

A require statement for a class permission adds that permission to the
class representation for the current module.  In case the resulting
class would have more than the supported amount of 32 permissions
assigned the resulting binary module will fail to load at link-time
without an informative error message (since [1]).

Bail out if adding a permission would result in a class having more then
the supported amount of 32 permissions assigned.

[1]: https://github.com/SELinuxProject/selinux/commit/97af65f69644a3233d073ae93980a0d2e51f42e1

Closes: https://github.com/SELinuxProject/selinux/issues/356
Reported-by: Julie Pichon
Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
---
 checkpolicy/module_compiler.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/checkpolicy/module_compiler.c b/checkpolicy/module_compiler.c
index 129650fa..3188af89 100644
--- a/checkpolicy/module_compiler.c
+++ b/checkpolicy/module_compiler.c
@@ -851,6 +851,14 @@ int require_class(int pass)
 				free(perm_id);
 				return -1;
 			}
+			if (datum->permissions.nprim >= PERM_SYMTAB_SIZE) {
+				yyerror2("Class %s would have too many permissions "
+					 "to fit in an access vector with permission %s",
+					 policydbp->p_class_val_to_name[datum->s.value - 1],
+					 perm_id);
+				free(perm_id);
+				return -1;
+			}
 			allocated = 1;
 			if ((perm = malloc(sizeof(*perm))) == NULL) {
 				yyerror("Out of memory!");
-- 
2.36.1