[PATCH 6/6] proc: Set correct userns for new proc super created by a new pid_namespace

From: David Howells
Date: Tue Aug 21 2018 - 05:55:41 EST


From: Andrei Vagin <avagin@xxxxxxxxxx>

Fix the setting up a new proc superblock for a new pid_namespace such that
the user_ns for that proc superblock needs to be taken from the new
pid_namespace and not the active process.

Signed-off-by: Andrei Vagin <avagin@xxxxxxxxx>
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
---

fs/proc/root.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/fs/proc/root.c b/fs/proc/root.c
index 1d6e5bfa30cc..1419b48a89ab 100644
--- a/fs/proc/root.c
+++ b/fs/proc/root.c
@@ -315,6 +315,11 @@ int pid_ns_prepare_proc(struct pid_namespace *ns)
if (IS_ERR(fc))
return PTR_ERR(fc);

+ if (fc->user_ns != ns->user_ns) {
+ put_user_ns(fc->user_ns);
+ fc->user_ns = get_user_ns(ns->user_ns);
+ }
+
ctx = fc->fs_private;
if (ctx->pid_ns != ns) {
put_pid_ns(ctx->pid_ns);