From: ebiederm@xmission.com (Eric W. Biederman)
To: "Luck\, Tony" <tony.luck@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Andi Kleen <ak@linux.intel.com>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Joe Konno <joe.konno@linux.intel.com>,
"linux-efi\@vger.kernel.org" <linux-efi@vger.kernel.org>,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
Jeremy Kerr <jk@ozlabs.org>, Matthew Garrett <mjg59@google.com>,
Peter Jones <pjones@redhat.com>,
"Andy Lutomirski" <luto@kernel.org>,
James Bottomley <james.bottomley@hansenpartnership.com>
Subject: Re: [PATCH] efivarfs: Limit the rate for non-root to read files
Date: Thu, 22 Feb 2018 11:10:22 -0600 [thread overview]
Message-ID: <87efld9cht.fsf@xmission.com> (raw)
In-Reply-To: <3908561D78D1C84285E8C5FCA982C28F7B37FE28@ORSMSX110.amr.corp.intel.com> (Tony Luck's message of "Thu, 22 Feb 2018 05:34:01 +0000")
"Luck, Tony" <tony.luck@intel.com> writes:
>> - add a per-user mutex, and do the usleep inside of it, so that
>> anybody who tries to do a thousand threads will just be serialized by
>> the mutex.
>>
>> Note that the mutex needs to be per-user, because otherwise it will be
>> a DoS for the other users.
>
> I can try that tomorrow (adding the per-user mutex to struct user_struct
> right next to the ratelimit I added.
Another possibility is to cache the files in the page cache. That will
reduce re-reads of the same data to the maximum extent.
If efi has a chance of changing variables behind our back we might want
something that would have a timeout on how long the data is cached,
and we probably want to make the caching policy write-trough not
write-back.
I just suggest this as it seems like a much more tried and true solution.
Eric
next prev parent reply other threads:[~2018-02-22 17:10 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-15 18:22 [PATCH 0/2] efivars: reading variables can generate SMIs Joe Konno
2018-02-15 18:22 ` [PATCH 1/2] fs/efivarfs: restrict inode permissions Joe Konno
2018-02-20 19:18 ` Andy Lutomirski
2018-02-20 21:18 ` Luck, Tony
2018-02-20 21:22 ` Matthew Garrett
2018-02-20 21:32 ` Luck, Tony
2018-02-20 21:35 ` Matthew Garrett
2018-02-20 22:01 ` Linus Torvalds
2018-02-20 23:30 ` Luck, Tony
2018-02-20 23:39 ` Matthew Garrett
2018-02-20 23:50 ` Luck, Tony
2018-02-21 0:49 ` Linus Torvalds
2018-02-21 1:05 ` Luck, Tony
2018-02-21 2:16 ` Linus Torvalds
2018-02-21 9:03 ` Ard Biesheuvel
2018-02-21 18:02 ` Linus Torvalds
2018-02-21 18:21 ` Andi Kleen
2018-02-21 19:47 ` Luck, Tony
2018-02-21 19:50 ` Linus Torvalds
2018-02-21 19:58 ` Luck, Tony
2018-02-21 20:40 ` Linus Torvalds
2018-02-22 1:45 ` [PATCH] efivarfs: Limit the rate for non-root to read files Luck, Tony
2018-02-22 1:58 ` Linus Torvalds
2018-02-22 5:34 ` Luck, Tony
2018-02-22 17:10 ` Eric W. Biederman [this message]
[not found] ` <CA+55aFy0hRexJkLbN7t31LjfGr4Ae0W5g6sBMqHHJi8aYuGKeA@mail.gmail.com>
[not found] ` <612E894E-62C8-4155-AED8-D53702EDC8DC@intel.com>
[not found] ` <CA+55aFxeBaTbwvbWqx1MKYjKKzLUs=1O43Bx2=JaO8qrnY-8HA@mail.gmail.com>
2018-02-22 17:15 ` [PATCH v2] " Luck, Tony
2018-02-22 17:39 ` Linus Torvalds
2018-02-22 17:54 ` Luck, Tony
2018-02-22 18:07 ` Linus Torvalds
2018-02-22 18:08 ` Ard Biesheuvel
2018-02-23 20:34 ` Andy Lutomirski
2018-02-23 19:47 ` [PATCH] " Peter Jones
2018-02-21 19:52 ` [PATCH 1/2] fs/efivarfs: restrict inode permissions Linus Torvalds
2018-02-24 20:06 ` Alan Cox
2018-02-25 10:56 ` Ard Biesheuvel
2018-02-21 0:49 ` Peter Jones
2018-02-20 23:19 ` Andy Lutomirski
2018-02-15 18:22 ` [PATCH 2/2] efi: restrict top-level attribute permissions Joe Konno
2018-02-16 10:41 ` [PATCH 0/2] efivars: reading variables can generate SMIs Ard Biesheuvel
2018-02-16 10:55 ` Borislav Petkov
2018-02-16 10:58 ` Ard Biesheuvel
2018-02-16 11:08 ` Borislav Petkov
2018-02-16 11:18 ` Ard Biesheuvel
2018-02-16 18:48 ` Joe Konno
2018-02-16 18:58 ` Borislav Petkov
2018-02-16 19:22 ` Peter Jones
2018-02-16 19:31 ` Ard Biesheuvel
2018-02-16 19:51 ` Matthew Garrett
2018-02-16 19:32 ` Luck, Tony
2018-02-16 19:54 ` Peter Jones
2018-02-16 20:51 ` James Bottomley
2018-02-16 21:09 ` Luck, Tony
2018-02-16 21:45 ` Andy Lutomirski
2018-02-16 21:58 ` Matthew Garrett
2018-02-16 22:02 ` Luck, Tony
2018-02-16 22:03 ` Matthew Garrett
2018-02-17 18:12 ` Andy Lutomirski
2018-02-16 22:05 ` Peter Jones
2018-02-17 9:36 ` Ard Biesheuvel
2018-02-17 16:17 ` Andi Kleen
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