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libsepol/cil: Do not resolve arguments to declarations in the call

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Lorenzo Ceragioli <lorenzo.ceragioli@phd.unipi.it> noted that the
following policy:
  (type a)
  (block A
    (macro m ((type x))
      (type a)
      (allow x x (file (read))))
  )
  (block B
    (call A.m(a))
  )
results in the allow rule (allow B.a B.a (file(read))). This makes
no sense because the "a" being passed as an argument has to be the
global "a" and not the "a" defined in the macro.

This behavior occurs because the call arguments are resolved AFTER
the macro body has been copied and the declaration of "a" in the
macro has been added to block B's namespace, so this is the "a"
that the call argument resolves to, rather than the one in the
global namespace.

When resolving call arguments, check if the datum found belongs to
a declaration in the call. If it does, then remove the datum from
the symbol table, re-resolve the argument, and add the datum back
into the symbol table.

Signed-off-by: James Carter <jwcart2@gmail.com>
This commit is contained in:
James Carter 2021-05-11 14:22:53 -04:00
parent bccec36a76
commit aa8ac8ffaf
1 changed files with 27 additions and 1 deletions
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28
libsepol/cil/src/cil_resolve_ast.c
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@ -3263,11 +3263,37 @@ int cil_resolve_call_args(struct cil_tree_node *current, void *extra_args)
}
if (sym_index != CIL_SYM_UNKNOWN) {
rc = cil_resolve_name(current, arg->arg_str, sym_index, extra_args, &(arg->arg));
struct cil_symtab_datum *datum;
struct cil_tree_node *n;
rc = cil_resolve_name(current, arg->arg_str, sym_index, extra_args, &datum);
if (rc != SEPOL_OK) {
cil_tree_log(current, CIL_ERR, "Failed to resolve %s in call argument list", arg->arg_str);
goto exit;
}
arg->arg = datum;
n = NODE(datum);
while (n && n->flavor != CIL_ROOT) {
if (n == current) {
symtab_t *s = datum->symtab;
/* Call arg should not resolve to declaration in the call
* Need to remove datum temporarily to resolve to a datum outside
* the call.
*/
cil_symtab_remove_datum(datum);
rc = cil_resolve_name(current, arg->arg_str, sym_index, extra_args, &(arg->arg));
if (rc != SEPOL_OK) {
cil_tree_log(current, CIL_ERR, "Failed to resolve %s in call argument list", arg->arg_str);
goto exit;
}
rc = cil_symtab_insert(s, datum->name, datum, NULL);
if (rc != SEPOL_OK) {
cil_tree_log(current, CIL_ERR, "Failed to re-insert datum while resolving %s in call argument list", arg->arg_str);
goto exit;
}
break;
}
n = n->parent;
}
}
}