Re: [PATCH 08/10 v3] libsepol/cil: Add CIL bounds checking and reporting.

[Steve Lawrence <slawrence@tresys.com>]

On 06/19/2015 02:19 PM, James Carter wrote:
> Use the libsepol bounds checking to check for and report user and
> role bounds violations.
> 
> For type bounds checking, use libsepol bounds checking to determine
> if there is a violation for a given type. For each violation display
> an error message that includes the CIL AST from the root node to the
> node of the rule causing the violation.
> 
> Example error report:
> Child type b_t3_c exceeds bounds of parent b_t3
>   (allow b_t3_c b_tc (file (write)))
>     <root>
>     booleanif at line 148633 of cil.conf.bounds
>     true at line 148634 of cil.conf.bounds
>     allow at line 148636 of cil.conf.bounds
>       (allow b_t3_c b_tc (file (read write)))
> 
> Signed-off-by: James Carter <jwcart2@tycho.nsa.gov>

Acked-by: Steve Lawrence <slawrence@tresys.com>

> ---
>  libsepol/cil/src/cil_binary.c | 135 ++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 135 insertions(+)
> 
> diff --git a/libsepol/cil/src/cil_binary.c b/libsepol/cil/src/cil_binary.c
> index 066184a..6d095db 100644
> --- a/libsepol/cil/src/cil_binary.c
> +++ b/libsepol/cil/src/cil_binary.c
> @@ -3903,6 +3903,130 @@ exit:
>  	return rc;
>  }
>  
> +static struct cil_list *cil_classperms_from_sepol(policydb_t *pdb, uint16_t class, uint32_t data, struct cil_class *class_value_to_cil[], struct cil_perm **perm_value_to_cil[])
> +{
> +	struct cil_classperms *cp;
> +	struct cil_list *cp_list;
> +	class_datum_t *sepol_class = pdb->class_val_to_struct[class - 1];
> +	unsigned i;
> +
> +	cil_classperms_init(&cp);
> +
> +	cp->class = class_value_to_cil[class];
> +	if (!cp->class) goto exit;
> +
> +	cil_list_init(&cp->perms, CIL_PERM);
> +	for (i = 0; i < sepol_class->permissions.nprim; i++) {
> +		struct cil_perm *perm;
> +		if ((data & (1 << i)) == 0) continue;
> +		perm = perm_value_to_cil[class][i+1];
> +		if (!perm) goto exit;
> +		cil_list_append(cp->perms, CIL_PERM, perm);
> +	}
> +
> +	cil_list_init(&cp_list, CIL_CLASSPERMS);
> +	cil_list_append(cp_list, CIL_CLASSPERMS, cp);
> +
> +	return cp_list;
> +
> +exit:
> +	cil_log(CIL_ERR,"Failed to create CIL class-permissions from sepol values\n");
> +	return NULL;
> +}
> +
> +static int cil_avrule_from_sepol(policydb_t *pdb, avtab_ptr_t sepol_rule, struct cil_avrule *cil_rule, void *type_value_to_cil[], struct cil_class *class_value_to_cil[], struct cil_perm **perm_value_to_cil[])
> +{
> +	int rc = SEPOL_ERR;
> +	avtab_key_t *k = &sepol_rule->key;
> +	avtab_datum_t *d = &sepol_rule->datum;
> +	cil_rule->src = type_value_to_cil[k->source_type];
> +	if (!cil_rule->src) goto exit;
> +
> +	cil_rule->tgt = type_value_to_cil[k->target_type];
> +	if (!cil_rule->tgt) goto exit;
> +
> +	cil_rule->classperms = cil_classperms_from_sepol(pdb, k->target_class, d->data, class_value_to_cil, perm_value_to_cil);
> +	if (!cil_rule->classperms) goto exit;
> +
> +	return SEPOL_OK;
> +
> +exit:
> +	cil_log(CIL_ERR,"Failed to create CIL AV rule from sepol values\n");
> +	return rc;
> +}
> +
> +static int cil_check_type_bounds(const struct cil_db *db, policydb_t *pdb, void *type_value_to_cil, struct cil_class *class_value_to_cil[], struct cil_perm **perm_value_to_cil[])
> +{
> +	int rc = SEPOL_OK;
> +	int i;
> +
> +	for (i = 0; i < db->num_types; i++) {
> +		type_datum_t *child;
> +		type_datum_t *parent;
> +		avtab_ptr_t bad = NULL;
> +		int numbad = 0;
> +		struct cil_type *t = db->val_to_type[i];
> +
> +		if (!t->bounds) continue;
> +
> +		rc = __cil_get_sepol_type_datum(pdb, DATUM(t), &child);
> +		if (rc != SEPOL_OK) goto exit;
> +
> +		rc = __cil_get_sepol_type_datum(pdb, DATUM(t->bounds), &parent);
> +		if (rc != SEPOL_OK) goto exit;
> +
> +		rc = bounds_check_type(NULL, pdb, child->s.value, parent->s.value, &bad, &numbad);
> +		if (rc != SEPOL_OK) goto exit;
> +
> +		if (bad) {
> +			avtab_ptr_t cur;
> +			struct cil_avrule target;
> +
> +			target.rule_kind = CIL_AVRULE_ALLOWED;
> +			target.src_str = NULL;
> +			target.tgt_str = NULL;
> +
> +			cil_log(CIL_ERR, "Child type %s exceeds bounds of parent %s\n",
> +				t->datum.fqn, t->bounds->datum.fqn);
> +			for (cur = bad; cur; cur = cur->next) {
> +				struct cil_list_item *i2;
> +				struct cil_list *matching;
> +				struct cil_tree_node *n;
> +
> +				rc = cil_avrule_from_sepol(pdb, cur, &target, type_value_to_cil, class_value_to_cil, perm_value_to_cil);
> +				if (rc != SEPOL_OK) {
> +					cil_log(CIL_ERR, "Failed to convert sepol avrule to CIL\n");
> +					goto exit;
> +				}
> +				__cil_print_rule("  ", "allow", &target);
> +				cil_list_init(&matching, CIL_NODE);
> +				rc = cil_find_matching_avrule_in_ast(db->ast->root, CIL_AVRULE, &target, matching, CIL_FALSE);
> +				if (rc) {
> +					cil_log(CIL_ERR, "Error occurred while checking type bounds\n");
> +					cil_list_destroy(&matching, CIL_FALSE);
> +					cil_list_destroy(&target.classperms, CIL_TRUE);
> +					bounds_destroy_bad(bad);
> +					goto exit;
> +				}
> +
> +				cil_list_for_each(i2, matching) {
> +					__cil_print_parents("    ", (struct cil_tree_node *)i2->data);
> +				}
> +				i2 = matching->tail;
> +				n = i2->data;
> +				__cil_print_rule("      ", "allow", n->data);
> +				cil_log(CIL_ERR,"\n");
> +				cil_list_destroy(&matching, CIL_FALSE);
> +				cil_list_destroy(&target.classperms, CIL_TRUE);
> +			}
> +			bounds_destroy_bad(bad);
> +		}
> +	}
> +
> +exit:
> +	return rc;
> +}
> +
>  // assumes policydb is already allocated and initialized properly with things
>  // like policy type set to kernel and version set appropriately
>  int cil_binary_create_allocated_pdb(const struct cil_db *db, sepol_policydb_t *policydb)
> @@ -4022,6 +4146,17 @@ int cil_binary_create_allocated_pdb(const struct cil_db *db, sepol_policydb_t *p
>  		cil_log(CIL_INFO, "Checking Neverallows\n");
>  		rc = cil_check_neverallows(db, pdb, neverallows);
>  		if (rc != SEPOL_OK) goto exit;
> +
> +		cil_log(CIL_INFO, "Checking User Bounds\n");
> +		bounds_check_users(NULL, pdb);
> +
> +		cil_log(CIL_INFO, "Checking Role Bounds\n");
> +		bounds_check_roles(NULL, pdb);
> +
> +		cil_log(CIL_INFO, "Checking Type Bounds\n");
> +		rc = cil_check_type_bounds(db, pdb, type_value_to_cil, class_value_to_cil, perm_value_to_cil);
> +		if (rc != SEPOL_OK) goto exit;
> +
>  	}
>  
>  	rc = SEPOL_OK;
>