ns proc: Add support for the user namespace

Add the basic namespace file support, but do not
add support for setns.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

5 files changed, 48 insertions, 0 deletions

diff --git a/fs/proc/namespaces.c b/fs/proc/namespaces.c
index 65bfeec5fcb3f6..f500ed94e58ed0 100644
--- a/fs/proc/namespaces.c
+++ b/fs/proc/namespaces.c
@@ -26,6 +26,9 @@ static const struct proc_ns_operations *ns_entries[] = {
 	&ipcns_operations,
 #endif
 	&mntns_operations,
+#ifdef CONFIG_USER_NS
+	&userns_operations,
+#endif
 };
 
 static const struct file_operations ns_file_operations = {
diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h
index 9ca36ea3878cc3..86d4b399bc3e39 100644
--- a/include/linux/proc_fs.h
+++ b/include/linux/proc_fs.h
@@ -31,6 +31,7 @@ enum {
 	PROC_ROOT_INO		= 1,
 	PROC_IPC_INIT_INO	= 0xEFFFFFFFU,
 	PROC_UTS_INIT_INO	= 0xEFFFFFFEU,
+	PROC_USER_INIT_INO	= 0xEFFFFFFDU,
 };
 
 
@@ -272,6 +273,7 @@ extern const struct proc_ns_operations netns_operations;
 extern const struct proc_ns_operations utsns_operations;
 extern const struct proc_ns_operations ipcns_operations;
 extern const struct proc_ns_operations mntns_operations;
+extern const struct proc_ns_operations userns_operations;
 
 union proc_op {
 	int (*proc_get_link)(struct inode *, struct path *);
diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
index faf467944bafc0..5ecc9888c22bb8 100644
--- a/include/linux/user_namespace.h
+++ b/include/linux/user_namespace.h
@@ -14,6 +14,7 @@ struct user_namespace {
 	struct hlist_head	uidhash_table[UIDHASH_SZ];
 	struct user_struct	*creator;
 	struct work_struct	destroyer;
+	unsigned int		proc_inum;
 };
 
 extern struct user_namespace init_user_ns;
diff --git a/kernel/user.c b/kernel/user.c
index 9e03e9c1df8d47..867fc657c4587b 100644
--- a/kernel/user.c
+++ b/kernel/user.c
@@ -16,6 +16,7 @@
 #include <linux/interrupt.h>
 #include <linux/module.h>
 #include <linux/user_namespace.h>
+#include <linux/proc_fs.h>
 
 /*
  * userns count is 1 for root user, 1 for init_uts_ns,
@@ -26,6 +27,7 @@ struct user_namespace init_user_ns = {
 		.refcount	= ATOMIC_INIT(3),
 	},
 	.creator = &root_user,
+	.proc_inum = PROC_USER_INIT_INO,
 };
 EXPORT_SYMBOL_GPL(init_user_ns);
 
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index 9da289c34f22f1..3c2e8f8d35bc52 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -11,6 +11,7 @@
 #include <linux/user_namespace.h>
 #include <linux/highuid.h>
 #include <linux/cred.h>
+#include <linux/proc_fs.h>
 
 static struct kmem_cache *user_ns_cachep __read_mostly;
 
@@ -27,11 +28,18 @@ int create_user_ns(struct cred *new)
 	struct user_namespace *ns;
 	struct user_struct *root_user;
 	int n;
+	int ret;
 
 	ns = kmem_cache_alloc(user_ns_cachep, GFP_KERNEL);
 	if (!ns)
 		return -ENOMEM;
 
+	ret = proc_alloc_inum(&ns->proc_inum);
+	if (ret) {
+		kmem_cache_free(user_ns_cachep, ns);
+		return ret;
+	}
+
 	kref_init(&ns->kref);
 
 	for (n = 0; n < UIDHASH_SZ; ++n)
@@ -40,6 +48,7 @@ int create_user_ns(struct cred *new)
 	/* Alloc new root user.  */
 	root_user = alloc_uid(ns, 0);
 	if (!root_user) {
+		proc_free_inum(ns->proc_inum);
 		kmem_cache_free(user_ns_cachep, ns);
 		return -ENOMEM;
 	}
@@ -73,6 +82,7 @@ static void free_user_ns_work(struct work_struct *work)
 	struct user_namespace *ns =
 		container_of(work, struct user_namespace, destroyer);
 	free_uid(ns->creator);
+	proc_free_inum(ns->proc_inum);
 	kmem_cache_free(user_ns_cachep, ns);
 }
 
@@ -135,3 +145,33 @@ static __init int user_namespaces_init(void)
 	return 0;
 }
 module_init(user_namespaces_init);
+
+static void *userns_get(struct task_struct *task)
+{
+	return get_user_ns(task_cred_xxx(task, user)->user_ns);
+}
+
+static void userns_put(void *ns)
+{
+	put_user_ns(ns);
+}
+
+static int userns_install(struct nsproxy *nsproxy, void *ns)
+{
+	return -EINVAL;
+}
+
+static unsigned int userns_inum(void *ns)
+{
+	struct user_namespace *user_ns = ns;
+	return user_ns->proc_inum;
+}
+
+const struct proc_ns_operations userns_operations = {
+	.name		= "user",
+	.type		= CLONE_NEWNS,
+	.get		= userns_get,
+	.put		= userns_put,
+	.install	= userns_install,
+	.inum		= userns_inum,
+};