AppArmor: add "file" details to securityfs

Create the "file" directory in the securityfs for tracking features
related to files.

Signed-off-by: Kees Cook <kees@ubuntu.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>
diff --git a/security/apparmor/apparmorfs.c b/security/apparmor/apparmorfs.c
index f30dada..f9d0b50 100644
--- a/security/apparmor/apparmorfs.c
+++ b/security/apparmor/apparmorfs.c
@@ -154,6 +154,9 @@
 	case AA_FS_TYPE_BOOLEAN:
 		seq_printf(seq, "%s\n", fs_file->v.boolean ? "yes" : "no");
 		break;
+	case AA_FS_TYPE_STRING:
+		seq_printf(seq, "%s\n", fs_file->v.string);
+		break;
 	case AA_FS_TYPE_U64:
 		seq_printf(seq, "%#08lx\n", fs_file->v.u64);
 		break;
@@ -180,6 +183,12 @@
 
 /** Base file system setup **/
 
+static struct aa_fs_entry aa_fs_entry_file[] = {
+	AA_FS_FILE_STRING("mask", "create read write exec append mmap_exec " \
+				  "link lock"),
+	{ }
+};
+
 static struct aa_fs_entry aa_fs_entry_domain[] = {
 	AA_FS_FILE_BOOLEAN("change_hat",	1),
 	AA_FS_FILE_BOOLEAN("change_hatv",	1),
@@ -190,6 +199,7 @@
 
 static struct aa_fs_entry aa_fs_entry_features[] = {
 	AA_FS_DIR("domain",			aa_fs_entry_domain),
+	AA_FS_DIR("file",			aa_fs_entry_file),
 	AA_FS_FILE_U64("capability",		VFS_CAP_FLAGS_MASK),
 	{ }
 };