From: Johannes Weiner <hannes@cmpxchg.org>
To: Michal Hocko <mhocko@suse.com>
Cc: Suren Baghdasaryan <surenb@google.com>,
tj@kernel.org, lizefan.x@bytedance.com, peterz@infradead.org,
johunt@akamai.com, keescook@chromium.org,
quic_sudaraja@quicinc.com, cgroups@vger.kernel.org,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/1] psi: remove 500ms min window size limitation for triggers
Date: Thu, 2 Mar 2023 12:58:57 -0500 [thread overview]
Message-ID: <ZADj4YX4uftK/Frh@cmpxchg.org> (raw)
In-Reply-To: <ZADf27Kx5mbFev+I@dhcp22.suse.cz>
On Thu, Mar 02, 2023 at 06:41:47PM +0100, Michal Hocko wrote:
> On Thu 02-03-23 08:13:54, Suren Baghdasaryan wrote:
> [...]
> > Let's roll this check without additional changes and then consolidate
> > the checking inside psi_trigger_create() in a separate patch. If
> > anybody objects to the late permission check we will just revert that
> > last change without affecting anything else.
>
> Permissions checks at write time are problematic because userspace
> cannot drop privileges. Also I think it would be an antipattern for how
> we do this in general.
The permissions can be checked against opener privileges through
file->f_cred. This allows dropping privileges, as well as passing the
fd to a trusted but unprivileged process to delegate trigger setup.
I agree with keeping it in open() for now. But it will matter when we
distinguish between privileged and unprivileged trigger parameters.
next prev parent reply other threads:[~2023-03-02 17:59 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-01 19:34 Suren Baghdasaryan
2023-03-01 20:07 ` Johannes Weiner
2023-03-01 20:48 ` Suren Baghdasaryan
2023-03-01 21:00 ` Kalesh Singh
2023-03-02 15:30 ` Johannes Weiner
2023-03-02 16:13 ` Suren Baghdasaryan
2023-03-02 17:41 ` Michal Hocko
2023-03-02 17:58 ` Johannes Weiner [this message]
2023-03-02 13:58 ` Michal Hocko
2023-03-02 16:08 ` Suren Baghdasaryan
2023-03-02 17:39 ` Michal Hocko
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