path: root/kernel/pid_namespace.c
diff options
authorEric W. Biederman <ebiederm@xmission.com>2017-04-29 14:12:15 -0500
committerEric W. Biederman <ebiederm@xmission.com>2017-07-20 07:43:58 -0500
commita2b426267c56773201f968fdb5eda6ab9ae94e34 (patch)
treeb58af67eb704fcd9d3306b0b725c935a1dbcadae /kernel/pid_namespace.c
parent5771a8c08880cdca3bfb4a3fc6d309d6bba20877 (diff)
userns,pidns: Verify the userns for new pid namespaces
It is pointless and confusing to allow a pid namespace hierarchy and the user namespace hierarchy to get out of sync. The owner of a child pid namespace should be the owner of the parent pid namespace or a descendant of the owner of the parent pid namespace. Otherwise it is possible to construct scenarios where a process has a capability over a parent pid namespace but does not have the capability over a child pid namespace. Which confusingly makes permission checks non-transitive. It requires use of setns into a pid namespace (but not into a user namespace) to create such a scenario. Add the function in_userns to help in making this determination. v2: Optimized in_userns by using level as suggested by: Kirill Tkhai <ktkhai@virtuozzo.com> Ref: 49f4d8b93ccf ("pidns: Capture the user namespace and filter ns_last_pid") Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Diffstat (limited to 'kernel/pid_namespace.c')
1 files changed, 4 insertions, 0 deletions
diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
index 74a5a7255b4d..4918314893bc 100644
--- a/kernel/pid_namespace.c
+++ b/kernel/pid_namespace.c
@@ -101,6 +101,10 @@ static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns
int i;
int err;
+ err = -EINVAL;
+ if (!in_userns(parent_pid_ns->user_ns, user_ns))
+ goto out;
err = -ENOSPC;
if (level > MAX_PID_NS_LEVEL)
goto out;

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