From c28525a26fa145cb5fd911fd2a3b9125a275677f Mon Sep 17 00:00:00 2001 From: James Carter Date: Mon, 21 Jun 2021 10:34:30 -0400 Subject: [PATCH] libsepol/cil: Properly check for loops in sets Commit 61fbdce666f24c4a118b249ece6b014d54b65074 (ibsepol/cil: Check for self-referential loops in sets) added checks for self-referential loops in user, role, type, and category sets. Unfortunately, this check ends up in an infinite loop if the set with the self-referential loop is used in a different set that is checked before the bad set. The problem with the old check is that only the initial datum is used for the check. Instead, use a stack to track all of the set datums that are currently involved as the check is made. A self-referential loop occurs if a duplicate datum is found for any of the datums in the stack. Signed-off-by: James Carter Acked-by: Nicolas Iooss --- libsepol/cil/src/cil_verify.c | 48 +++++++++++++++++++++++------------ 1 file changed, 32 insertions(+), 16 deletions(-) diff --git a/libsepol/cil/src/cil_verify.c b/libsepol/cil/src/cil_verify.c index 8e15a0e68a69..59397f70f2ea 100644 --- a/libsepol/cil/src/cil_verify.c +++ b/libsepol/cil/src/cil_verify.c @@ -44,6 +44,7 @@ #include "cil_tree.h" #include "cil_list.h" #include "cil_find.h" +#include "cil_stack.h" #include "cil_verify.h" @@ -430,9 +431,9 @@ int cil_verify_decl_does_not_shadow_macro_parameter(struct cil_macro *macro, str return SEPOL_OK; } -static int cil_verify_no_self_reference(enum cil_flavor flavor, struct cil_symtab_datum *datum, struct cil_symtab_datum *orig); +static int cil_verify_no_self_reference(enum cil_flavor flavor, struct cil_symtab_datum *datum, struct cil_stack *stack); -static int __verify_no_self_reference_in_expr(struct cil_list *expr, struct cil_symtab_datum *orig) +static int __verify_no_self_reference_in_expr(struct cil_list *expr, struct cil_stack *stack) { struct cil_list_item *item; int rc = SEPOL_OK; @@ -444,9 +445,9 @@ static int __verify_no_self_reference_in_expr(struct cil_list *expr, struct cil_ cil_list_for_each(item, expr) { if (item->flavor == CIL_DATUM) { struct cil_symtab_datum* datum = item->data; - rc = cil_verify_no_self_reference(FLAVOR(datum), datum, orig); + rc = cil_verify_no_self_reference(FLAVOR(datum), datum, stack); } else if (item->flavor == CIL_LIST) { - rc = __verify_no_self_reference_in_expr(item->data, orig); + rc = __verify_no_self_reference_in_expr(item->data, stack); } if (rc != SEPOL_OK) { return SEPOL_ERR; @@ -456,36 +457,47 @@ static int __verify_no_self_reference_in_expr(struct cil_list *expr, struct cil_ return SEPOL_OK; } -static int cil_verify_no_self_reference(enum cil_flavor flavor, struct cil_symtab_datum *datum, struct cil_symtab_datum *orig) +static int cil_verify_no_self_reference(enum cil_flavor flavor, struct cil_symtab_datum *datum, struct cil_stack *stack) { + struct cil_stack_item *item; + int i = 0; int rc = SEPOL_OK; - if (datum == orig) { - cil_tree_log(NODE(orig), CIL_ERR, "Self-reference found for %s", orig->name); - return SEPOL_ERR; - } else if (orig == NULL) { - orig = datum; + cil_stack_for_each(stack, i, item) { + struct cil_symtab_datum *prev = item->data; + if (datum == prev) { + cil_tree_log(NODE(datum), CIL_ERR, "Self-reference found for %s", datum->name); + return SEPOL_ERR; + } } switch (flavor) { case CIL_USERATTRIBUTE: { struct cil_userattribute *attr = (struct cil_userattribute *)datum; - rc = __verify_no_self_reference_in_expr(attr->expr_list, orig); + cil_stack_push(stack, CIL_DATUM, datum); + rc = __verify_no_self_reference_in_expr(attr->expr_list, stack); + cil_stack_pop(stack); break; } case CIL_ROLEATTRIBUTE: { struct cil_roleattribute *attr = (struct cil_roleattribute *)datum; - rc = __verify_no_self_reference_in_expr(attr->expr_list, orig); + cil_stack_push(stack, CIL_DATUM, datum); + rc = __verify_no_self_reference_in_expr(attr->expr_list, stack); + cil_stack_pop(stack); break; } case CIL_TYPEATTRIBUTE: { struct cil_typeattribute *attr = (struct cil_typeattribute *)datum; - rc = __verify_no_self_reference_in_expr(attr->expr_list, orig); + cil_stack_push(stack, CIL_DATUM, datum); + rc = __verify_no_self_reference_in_expr(attr->expr_list, stack); + cil_stack_pop(stack); break; } case CIL_CATSET: { struct cil_catset *set = (struct cil_catset *)datum; - rc = __verify_no_self_reference_in_expr(set->cats->datum_expr, orig); + cil_stack_push(stack, CIL_DATUM, datum); + rc = __verify_no_self_reference_in_expr(set->cats->datum_expr, stack); + cil_stack_pop(stack); break; } default: @@ -1826,9 +1838,13 @@ int __cil_pre_verify_helper(struct cil_tree_node *node, uint32_t *finished, __at case CIL_USERATTRIBUTE: case CIL_ROLEATTRIBUTE: case CIL_TYPEATTRIBUTE: - case CIL_CATSET: - rc = cil_verify_no_self_reference(node->flavor, node->data, NULL); + case CIL_CATSET: { + struct cil_stack *stack; + cil_stack_init(&stack); + rc = cil_verify_no_self_reference(node->flavor, node->data, stack); + cil_stack_destroy(&stack); break; + } default: rc = SEPOL_OK; break; -- 2.32.0