From: "Luck, Tony" <tony.luck@intel.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Joe Konno <joe.konno@linux.intel.com>,
linux-efi@vger.kernel.org,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Matthew Garrett <matthew.garrett@nebula.com>,
Jeremy Kerr <jk@ozlabs.org>, Andi Kleen <ak@linux.intel.com>,
Matthew Garrett <mjg59@google.com>,
Peter Jones <pjones@redhat.com>,
Andy Lutomirski <luto@kernel.org>,
James Bottomley <james.bottomley@hansenpartnership.com>
Subject: Re: [PATCH 1/2] fs/efivarfs: restrict inode permissions
Date: Tue, 20 Feb 2018 15:30:09 -0800 [thread overview]
Message-ID: <20180220233008.55rfm7zw62hrao5p@agluck-desk> (raw)
In-Reply-To: <CA+55aFzjyB=E+=q-W9oYZ7Py7nJwm8YQHFjfbWTib6wvkP9B_A@mail.gmail.com>
On Tue, Feb 20, 2018 at 02:01:51PM -0800, Linus Torvalds wrote:
> And just on general principlies, I don't want to see weasel-wordy
> commit messages like
>
> "Reading certain EFI variables trigger SMIs"
>
> I understand *writing* them causing SMI's due to some flash protection
> scheme. What's the reading thing? And why aren't we calling that
> garbage out?
Too much weasel there. Should say:
EFI[1] stinks. Reading any file in /sys/firmware/efi/efivars/ generates
4 (yes FOUR!) SMIs.
# rdmsr 0x34
14e2
# cat /sys/firmware/efi/efivars/ConIn-8be4df61-93ca-11d2-aa0d-00e098032b8c > /dev/null
# rdmsr 0x34
14e6
-Tony
[1] I didn't dig through the Linux code to check whether we manage to
get those four SMIs from a single EFI call, or whether we make multiple
EFI calls to open/read/close one file. It is possible that we stink a
bit too if we are doing more EFI calls than required.
next prev parent reply other threads:[~2018-02-20 23:30 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 [this message]
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
[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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