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authorAndrey Vagin <avagin@openvz.org>2016-09-06 10:47:13 +0300
committerEric W. Biederman <ebiederm@xmission.com>2016-09-23 03:59:39 +0300
commitbcac25a58bfc6bd79191ac5d7afb49bea96da8c9 (patch)
tree28a8ae71b2939267deba0807bcbbed28e77470c0 /kernel/user_namespace.c
parent29b4817d4018df78086157ea3a55c1d9424a7cfc (diff)
downloadlinux-bcac25a58bfc6bd79191ac5d7afb49bea96da8c9.tar.xz
kernel: add a helper to get an owning user namespace for a namespace
Return -EPERM if an owning user namespace is outside of a process current user namespace. v2: In a first version ns_get_owner returned ENOENT for init_user_ns. This special cases was removed from this version. There is nothing outside of init_user_ns, so we can return EPERM. v3: rename ns->get_owner() to ns->owner(). get_* usually means that it grabs a reference. Acked-by: Serge Hallyn <serge@hallyn.com> Signed-off-by: Andrei Vagin <avagin@openvz.org> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Diffstat (limited to 'kernel/user_namespace.c')
-rw-r--r--kernel/user_namespace.c24
1 files changed, 24 insertions, 0 deletions
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index 68f594212759..0ef683a03c20 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -1004,12 +1004,36 @@ static int userns_install(struct nsproxy *nsproxy, struct ns_common *ns)
return commit_creds(cred);
}
+struct ns_common *ns_get_owner(struct ns_common *ns)
+{
+ struct user_namespace *my_user_ns = current_user_ns();
+ struct user_namespace *owner, *p;
+
+ /* See if the owner is in the current user namespace */
+ owner = p = ns->ops->owner(ns);
+ for (;;) {
+ if (!p)
+ return ERR_PTR(-EPERM);
+ if (p == my_user_ns)
+ break;
+ p = p->parent;
+ }
+
+ return &get_user_ns(owner)->ns;
+}
+
+static struct user_namespace *userns_owner(struct ns_common *ns)
+{
+ return to_user_ns(ns)->parent;
+}
+
const struct proc_ns_operations userns_operations = {
.name = "user",
.type = CLONE_NEWUSER,
.get = userns_get,
.put = userns_put,
.install = userns_install,
+ .owner = userns_owner,
};
static __init int user_namespaces_init(void)