Messages in this thread | | | Date | Tue, 24 Mar 2020 12:52:12 +0100 | From | Oleg Nesterov <> | Subject | Re: [PATCH] ipc/mqueue.c: change __do_notify() to bypass check_kill_permission() |
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On 03/23, Eric W. Biederman wrote: > > So far what we have is a report Oleg has read somewhere that some > program doing something regressed, and his patch to fix that specific > program. This problem was not noticed for several years.
Yes, this was reported on bugzilla.redhat.com, I'll add you to CC list.
> Presumably the problem is that a message queue was written to by one > user and was read by another user to cause check_kill_permission to > fail. Can someone tell me if that was the case?
I do not know. Yoji, did you hit this bug or did you find it by code inspection ?
> So I am looking for something that makes it clear we are not removing > a permission checking and backporting a security hole.
Yes, I thought about this too. I can be easily wrong, please correct me, but I came to conclusion the old behaviour (no permission check) is fine security-wise.
> Further even if in the common case it is the right thing to do to remove > the permission check, the handling around exec looks bad enough that we > will be backporting a security hole if we don't fix that and backport > that at the same time.
could you explain what exactly you do not like wrt mq_notify/exec ? I must have missed something.
> p.s. I am grouchy as temporary fixes in this part of the code base > don't tend to be temporary and the entire signal/exec/ptrace world > is bordering on unmaintainble and incomprehensible as a result.
Eric, please feel free to make another fix you like more. I know that I can't convince you anyway, I won't argue. Oleg.
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