Jann Horn <ja...@google.com> writes: > On Mon, Oct 15, 2018 at 7:10 PM <nagarathnam.muthus...@oracle.com> wrote: >> @@ -1281,7 +1285,7 @@ static int userns_install(struct nsproxy *nsproxy, >> struct ns_common *ns) >> return -ENOMEM; >> >> put_user_ns(cred->user_ns); >> - set_cred_user_ns(cred, get_user_ns(user_ns)); >> + set_cred_user_ns(cred, get_user_ns(user_ns), 0); > > This looks bogus. With this, I think your restriction can be bypassed > if process A forks a child B, B creates a new user namespace, then A > enters the user namespace with setns() and has full capabilities. Am I > missing something?
Nope. I feel silly for missing that angle. Even without the full capabilities the userns_install angle will place you at the root of the mount namespace outside of the chroot. At which point I have visions of the special cases multiplying like bunnies make this work. Without a very strong case I don't like this at all. Eric
