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>

security/apparmor/apparmorfs.c

@@ -154,6 +154,9 @@ static int aa_fs_seq_show(struct seq_file *seq, void *v)
 	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 @@ const struct file_operations aa_fs_seq_file_ops = {
 
 /** 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_domain[] = {
 
 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),
 	{ }
 };

security/apparmor/include/apparmorfs.h

@@ -17,6 +17,7 @@
 
 enum aa_fs_type {
 	AA_FS_TYPE_BOOLEAN,
+	AA_FS_TYPE_STRING,
 	AA_FS_TYPE_U64,
 	AA_FS_TYPE_FOPS,
 	AA_FS_TYPE_DIR,
@@ -31,6 +32,7 @@ struct aa_fs_entry {
 	enum aa_fs_type v_type;
 	union {
 		bool boolean;
+		char *string;
 		unsigned long u64;
 		struct aa_fs_entry *files;
 	} v;
@@ -43,6 +45,10 @@ extern const struct file_operations aa_fs_seq_file_ops;
 	{ .name = (_name), .mode = 0444, \
 	  .v_type = AA_FS_TYPE_BOOLEAN, .v.boolean = (_value), \
 	  .file_ops = &aa_fs_seq_file_ops }
+#define AA_FS_FILE_STRING(_name, _value) \
+	{ .name = (_name), .mode = 0444, \
+	  .v_type = AA_FS_TYPE_STRING, .v.string = (_value), \
+	  .file_ops = &aa_fs_seq_file_ops }
 #define AA_FS_FILE_U64(_name, _value) \
 	{ .name = (_name), .mode = 0444, \
 	  .v_type = AA_FS_TYPE_U64, .v.u64 = (_value), \