[PATCH 14/17] fsinfo: Add an attribute that lists all the visible mounts in a namespace [ver #20]

@@ -296,6 +296,7 @@ static const struct fsinfo_attribute fsinfo_common_attributes[] = {
 	FSINFO_STRING	(FSINFO_ATTR_MOUNT_POINT,	fsinfo_generic_mount_point),
 	FSINFO_STRING	(FSINFO_ATTR_MOUNT_POINT_FULL,	fsinfo_generic_mount_point_full),
 	FSINFO_LIST	(FSINFO_ATTR_MOUNT_CHILDREN,	fsinfo_generic_mount_children),
+	FSINFO_LIST	(FSINFO_ATTR_MOUNT_ALL,		fsinfo_generic_mount_all),
 	{}
 };
 

@@ -102,6 +102,7 @@ extern int fsinfo_generic_mount_topology(struct path *, struct fsinfo_context *)
 extern int fsinfo_generic_mount_point(struct path *, struct fsinfo_context *);
 extern int fsinfo_generic_mount_point_full(struct path *, struct fsinfo_context *);
 extern int fsinfo_generic_mount_children(struct path *, struct fsinfo_context *);
+extern int fsinfo_generic_mount_all(struct path *, struct fsinfo_context *);
 
 /*
  * fs_struct.c

@@ -4494,4 +4494,41 @@ int fsinfo_generic_mount_children(struct path *path, struct fsinfo_context *ctx)
 	return ctx->usage;
 }
 
+/*
+ * Return information about all the mounts in the namespace referenced by the
+ * path.
+ */
+int fsinfo_generic_mount_all(struct path *path, struct fsinfo_context *ctx)
+{
+	struct mnt_namespace *ns;
+	struct mount *m, *p;
+	struct path chroot;
+	bool allow;
+
+	m = real_mount(path->mnt);
+	ns = m->mnt_ns;
+
+	get_fs_root(current->fs, &chroot);
+	rcu_read_lock();
+	allow = are_paths_connected(&chroot, path) || capable(CAP_SYS_ADMIN);
+	rcu_read_unlock();
+	path_put(&chroot);
+	if (!allow)
+		return -EPERM;
+
+	down_read(&namespace_sem);
+
+	list_for_each_entry(p, &ns->list, mnt_list) {
+		struct path mnt_root;
+
+		mnt_root.mnt	= &p->mnt;
+		mnt_root.dentry	= p->mnt.mnt_root;
+		if (are_paths_connected(path, &mnt_root))
+			fsinfo_store_mount(ctx, p, p == m);
+	}
+
+	up_read(&namespace_sem);
+	return ctx->usage;
+}
+
 #endif /* CONFIG_FSINFO */

@@ -37,6 +37,7 @@
 #define FSINFO_ATTR_MOUNT_POINT_FULL	0x203	/* Absolute path of mount (string) */
 #define FSINFO_ATTR_MOUNT_TOPOLOGY	0x204	/* Mount object topology */
 #define FSINFO_ATTR_MOUNT_CHILDREN	0x205	/* Children of this mount (list) */
+#define FSINFO_ATTR_MOUNT_ALL		0x206	/* List all mounts in a namespace (list) */
 
 #define FSINFO_ATTR_AFS_CELL_NAME	0x300	/* AFS cell name (string) */
 #define FSINFO_ATTR_AFS_SERVER_NAME	0x301	/* Name of the Nth server (string) */

@@ -129,6 +130,8 @@ struct fsinfo_mount_topology {
 /*
  * Information struct element for fsinfo(FSINFO_ATTR_MOUNT_CHILDREN).
  * - An extra element is placed on the end representing the parent mount.
+ *
+ * Information struct element for fsinfo(FSINFO_ATTR_MOUNT_ALL).
  */
 struct fsinfo_mount_child {
 	__u64	mnt_unique_id;		/* Kernel-lifetime unique mount ID */

@@ -140,6 +143,7 @@ struct fsinfo_mount_child {
 };
 
 #define FSINFO_ATTR_MOUNT_CHILDREN__STRUCT struct fsinfo_mount_child
+#define FSINFO_ATTR_MOUNT_ALL__STRUCT struct fsinfo_mount_child
 
 /*
  * Information struct for fsinfo(FSINFO_ATTR_STATFS).

@@ -363,6 +363,27 @@ static void dump_fsinfo_generic_mount_children(void *reply, unsigned int size)
 	       r->mnt_notify_sum, mp);
 }
 
+static void dump_fsinfo_generic_mount_all(void *reply, unsigned int size)
+{
+	struct fsinfo_mount_child *r = reply;
+	ssize_t mplen;
+	char path[32], *mp;
+
+	struct fsinfo_params params = {
+		.flags		= FSINFO_FLAGS_QUERY_MOUNT,
+		.request	= FSINFO_ATTR_MOUNT_POINT_FULL,
+	};
+
+	sprintf(path, "%u", r->mnt_id);
+	mplen = get_fsinfo(path, "FSINFO_ATTR_MOUNT_POINT_FULL", &params, (void **)&mp);
+	if (mplen < 0)
+		mp = "-";
+
+	printf("%5x %5x %12llx %10u %s\n",
+	       r->mnt_id, r->parent_id, (unsigned long long)r->mnt_unique_id,
+	       r->mnt_notify_sum, mp);
+}
+
 static void dump_afs_fsinfo_server_address(void *reply, unsigned int size)
 {
 	struct fsinfo_afs_server_address *f = reply;

@@ -490,6 +511,7 @@ static const struct fsinfo_attribute fsinfo_attributes[] = {
 	FSINFO_STRING_N	(FSINFO_ATTR_MOUNT_POINT,	string),
 	FSINFO_STRING_N	(FSINFO_ATTR_MOUNT_POINT_FULL,	string),
 	FSINFO_LIST	(FSINFO_ATTR_MOUNT_CHILDREN,	fsinfo_generic_mount_children),
+	FSINFO_LIST	(FSINFO_ATTR_MOUNT_ALL,		fsinfo_generic_mount_all),
 
 	FSINFO_STRING	(FSINFO_ATTR_AFS_CELL_NAME,	string),
 	FSINFO_STRING	(FSINFO_ATTR_AFS_SERVER_NAME,	string),