On Thu, 2017-10-05 at 18:27 +0200, Oleg Nesterov wrote: > On 10/03, Jürg Billeter wrote: > > > > My use case is to provide a way for a process to spawn a child and > > ensure that no descendants survive when that child dies. Avoiding > > runaway processes is desirable in many situations. My motivation is > > very lightweight (nested) sandboxing (every process is potentially > > sandboxed). > > > > I.e., pid namespaces would be a pretty good fit (assuming they are > > sufficiently lightweight) but CLONE_NEWPID > > sorry if this was already discussed, I didn't read this thread yet... > > if CLONE_NEWPID is not suitable for any reason. We already have > PR_SET_CHILD_SUBREAPER. Perhaps we can simply add another > PR_SET_KILL_ALL_DESCEDANTS_ON_EXIT? we can use walk_process_tree() > to send SIGKILL.
Yes, this is an option. However, after the discussion in this thread I believe it would be better to drop the CAP_SYS_ADMIN requirement for CLONE_NEWPID (when no_new_privs is set) as this would avoid adding another API and code path for a similar effect. I'm interested in possible security concerns about such a change. Adding Andy Lutomirski to cc. Jürg
