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| author | Andrey Vagin <avagin@openvz.org> | 2016-09-06 10:47:13 +0300 |
|---|---|---|
| committer | Eric W. Biederman <ebiederm@xmission.com> | 2016-09-23 03:59:39 +0300 |
| commit | bcac25a58bfc6bd79191ac5d7afb49bea96da8c9 (patch) | |
| tree | 28a8ae71b2939267deba0807bcbbed28e77470c0 /kernel/user_namespace.c | |
| parent | 29b4817d4018df78086157ea3a55c1d9424a7cfc (diff) | |
| download | linux-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.c | 24 |
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) |