[apparmor] [PATCH 6/6] libapparmor: Allow creating a kernel_interface with a NULL kernel_features

[Tyler Hicks]

The most common case when creating an aa_kernel_interface object will be
to do so while using the current kernel's feature set for the
kernel_features parameter. Rather than have callers instantiate their
own aa_features object in this situation, aa_kernel_interface_new()
should do it for them if they specify NULL for the kernel_features
parameter.

Signed-off-by: Tyler Hicks <tyhicks at canonical.com>
---
 libraries/libapparmor/src/kernel_interface.c | 18 ++++++++++++++----
 tests/regression/apparmor/aa_policy_cache.c  |  9 +--------
 2 files changed, 15 insertions(+), 12 deletions(-)

diff --git a/libraries/libapparmor/src/kernel_interface.c b/libraries/libapparmor/src/kernel_interface.c
index 6ab20ea..15b171f 100644
--- a/libraries/libapparmor/src/kernel_interface.c
+++ b/libraries/libapparmor/src/kernel_interface.c
@@ -198,7 +198,9 @@ static int write_policy_file_to_iface(aa_kernel_interface *kernel_interface,
  * aa_kernel_interface_new - create a new kernel_interface from an optional path
  * @kernel_interface: will point to the address of an allocated and initialized
  *                    aa_kernel_interface object upon success
- * @kernel_features: features representing the currently running kernel
+ * @kernel_features: features representing the currently running kernel (can be
+ *                   NULL and the features of the currently running kernel will
+ *                   be used)
  * @apparmorfs: path to the apparmor directory of the mounted securityfs (can
  *              be NULL and the path will be auto discovered)
  *
@@ -223,9 +225,17 @@ int aa_kernel_interface_new(aa_kernel_interface **kernel_interface,
 	aa_kernel_interface_ref(ki);
 	ki->dirfd = -1;
 
-	ki->supports_setload = kernel_features ?
-			       aa_features_supports(kernel_features, set_load) :
-			       false;
+	if (kernel_features) {
+		aa_features_ref(kernel_features);
+	} else if (aa_features_new_from_kernel(&kernel_features) == -1) {
+		int save = errno;
+
+		aa_kernel_interface_unref(ki);
+		errno = save;
+		return -1;
+	}
+	ki->supports_setload = aa_features_supports(kernel_features, set_load);
+	aa_features_unref(kernel_features);
 
 	if (!apparmorfs) {
 		if (find_iface_dir(&alloced_apparmorfs) == -1) {
diff --git a/tests/regression/apparmor/aa_policy_cache.c b/tests/regression/apparmor/aa_policy_cache.c
index 03f7b5b..b221c98 100644
--- a/tests/regression/apparmor/aa_policy_cache.c
+++ b/tests/regression/apparmor/aa_policy_cache.c
@@ -120,16 +120,10 @@ out:
 
 static int test_remove_policy(const char *name)
 {
-	aa_features *features = NULL;
 	aa_kernel_interface *kernel_interface = NULL;
 	int rc = 1;
 
-	if (aa_features_new_from_kernel(&features)) {
-		perror("FAIL - aa_features_new_from_kernel");
-		goto out;
-	}
-
-	if (aa_kernel_interface_new(&kernel_interface, features, NULL)) {
+	if (aa_kernel_interface_new(&kernel_interface, NULL, NULL)) {
 		perror("FAIL - aa_kernel_interface_new");
 		goto out;
 	}
@@ -142,7 +136,6 @@ static int test_remove_policy(const char *name)
 	rc = 0;
 out:
 	aa_kernel_interface_unref(kernel_interface);
-	aa_features_unref(features);
 	return rc;
 }
 
-- 
2.1.4