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From 8470058934e89d1876b8e034d1ea818bde62b994 Mon Sep 17 00:00:00 2001
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From: James Carter <jwcart2@gmail.com>
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Date: Mon, 12 Jul 2021 09:50:38 -0400
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Subject: [PATCH] libsepol/cil: Fix handling category sets in an expression
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There are two problems that need to be addressed when resolving an
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expression with category sets.
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1. Only expand anonymous category sets in an expression.
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Commit 982ec302b67f3c7f8df667dadb67352b1e4a6d18 (libsepol/cil:
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Account for anonymous category sets in an expression) attempted to
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properly handle anonymous category sets when resolving category
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expressions. Unfortunately, it did not check whether a category set
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was actually an anonymous category set and expanded all category
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sets in an expression. If a category set refers to itself in the
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expression, then everything from the name of the category set to the
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end of the expression is ignored.
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For example, the rule "(categoryset cs (c0 cs c1 c2))", would be
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equivalent to the rule "(categoryset cs (c0))" as everything from
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"cs" to the end would be dropped. The secilc-fuzzer found that the
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rule "(categoryset cat (not cat))" would cause a segfault since
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"(not)" is not a valid expression and it is assumed to be valid
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during later evaluation because syntax checking has already been
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done.
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Instead, check whether or not the category set is anonymous before
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expanding it when resolving an expression.
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2. Category sets cannot be used in a category range
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A category range can be used to specify a large number of categories.
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The range "(range c0 c1023)" refers to 1024 categories. Only categories
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and category aliases can be used in a range. Determining if an
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identifier is a category, an alias, or a set can only be done after
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resolving the identifer.
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Keep track of the current operator as an expression is being resolved
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and if the expression involves categories and a category set is
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encountered, then return an error if the expression is a category
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range.
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Signed-off-by: James Carter <jwcart2@gmail.com>
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---
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libsepol/cil/src/cil_resolve_ast.c | 28 +++++++++++++++++++++-------
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1 file changed, 21 insertions(+), 7 deletions(-)
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diff --git a/libsepol/cil/src/cil_resolve_ast.c b/libsepol/cil/src/cil_resolve_ast.c
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index 145d4e7452dd..180073247617 100644
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--- a/libsepol/cil/src/cil_resolve_ast.c
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+++ b/libsepol/cil/src/cil_resolve_ast.c
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@@ -3228,6 +3228,7 @@ int cil_resolve_expr(enum cil_flavor expr_type, struct cil_list *str_expr, struc
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struct cil_symtab_datum *res_datum = NULL;
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enum cil_sym_index sym_index = CIL_SYM_UNKNOWN;
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struct cil_list *datum_sub_expr;
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+ enum cil_flavor op = CIL_NONE;
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switch (str_expr->flavor) {
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case CIL_BOOL:
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@@ -3263,14 +3264,24 @@ int cil_resolve_expr(enum cil_flavor expr_type, struct cil_list *str_expr, struc
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}
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if (sym_index == CIL_SYM_CATS && NODE(res_datum)->flavor == CIL_CATSET) {
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struct cil_catset *catset = (struct cil_catset *)res_datum;
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- if (!catset->cats->datum_expr) {
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- rc = cil_resolve_expr(expr_type, catset->cats->str_expr, &catset->cats->datum_expr, parent, extra_args);
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- if (rc != SEPOL_OK) {
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- goto exit;
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+ if (op == CIL_RANGE) {
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+ cil_tree_log(parent, CIL_ERR, "Category set not allowed in category range");
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+ rc = SEPOL_ERR;
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+ goto exit;
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+ }
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+ if (!res_datum->name) {
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+ /* Anonymous category sets need to be resolved when encountered */
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+ if (!catset->cats->datum_expr) {
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+ rc = cil_resolve_expr(expr_type, catset->cats->str_expr, &catset->cats->datum_expr, parent, extra_args);
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+ if (rc != SEPOL_OK) {
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+ goto exit;
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+ }
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}
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+ cil_copy_list(catset->cats->datum_expr, &datum_sub_expr);
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+ cil_list_append(*datum_expr, CIL_LIST, datum_sub_expr);
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+ } else {
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+ cil_list_append(*datum_expr, CIL_DATUM, res_datum);
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}
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- cil_copy_list(catset->cats->datum_expr, &datum_sub_expr);
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- cil_list_append(*datum_expr, CIL_LIST, datum_sub_expr);
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} else {
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if (sym_index == CIL_SYM_TYPES && (expr_type == CIL_CONSTRAIN || expr_type == CIL_VALIDATETRANS)) {
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cil_type_used(res_datum, CIL_ATTR_CONSTRAINT);
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@@ -3287,9 +3298,12 @@ int cil_resolve_expr(enum cil_flavor expr_type, struct cil_list *str_expr, struc
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break;
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}
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default:
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+ if (curr->flavor == CIL_OP) {
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+ op = (enum cil_flavor)(uintptr_t)curr->data;
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+ }
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cil_list_append(*datum_expr, curr->flavor, curr->data);
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break;
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- }
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+ }
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}
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return SEPOL_OK;
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--
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2.32.0
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