Messages in this thread | | | Date | Mon, 17 Mar 2008 02:17:51 +0300 | From | Oleg Nesterov <> | Subject | Re: [PATCH 5/5] ptrace: it is fun to strace /sbin/init |
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On 03/16, Roland McGrath wrote: > > > Ptracing of /sbin/init is not allowed. Of course, this is very dangerous, but > > may be useful. Introduce the kernel boot parameter to allow this. > > Personally I wouldn't mind losing all the ptrace/signals special cases for > init. (Just don't have a buggy init and expect not to crash, don't be root > and kill init, etc.) So this is fine by me. The conservative route of > changing it only with a boot option is the wise thing to do.
Great.
> > Unless I missed something, ptrace_get_task_struct() is pointless. It does not > > need to check "pid == 1", ptrace_attach() does this. It doesn't need tasklist. > > Agreed. It's a hold-over from when there was more hair in there. > > > It should be replaced with the generic find_get_task_by_vpid() which does not > > exist yet. > > I didn't see enough other uses to really warrant it. Most > find_task_by_vpid calls don't actually do get_task_struct. > Those that do want to do some other check inside rcu_read_lock > before deciding to bother with get_task_struct anyway. > So there is nothing wrong with ptrace just open-coding: > > rcu_read_lock(); > child = find_task_by_vpid(pid); > if (child) > get_task_struct(child); > rcu_read_unlock();
proc_task_lookup(), fill_pid(), attach_task_by_pid(), can use the new helper.
But yes sure, we can open-code this.
Oleg.
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