From: kirill@shutemov.name (Kirill A. Shutemov)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v4] kernel: add kcov code coverage
Date: Tue, 19 Jan 2016 15:05:43 +0200 [thread overview]
Message-ID: <20160119130543.GB20984@node.shutemov.name> (raw)
In-Reply-To: <CACT4Y+ZUKJOmATAASxM1qnbn=_0M9TAtTQYO0ecMtursLYvdww@mail.gmail.com>
On Tue, Jan 19, 2016 at 01:55:43PM +0100, Dmitry Vyukov wrote:
> >> +static int __init kcov_init(void)
> >> +{
> >> + if (!debugfs_create_file("kcov", 0666, NULL, NULL, &kcov_fops)) {
> >
> > Why 0666? May be 0600?.
>
> The idea is that it can be useful to fuzz-test under a normal user as well.
> This file is also guarded by debugfs mount permissions. Usually it is mounted
> as 0700, so normal users can't get access to it.
> However if one wants to fuzz-test under a normal user, he could mount
> debugfs as 0777 and get access to this file.
>
> I am not very strong about this, though. If you say, I will change it to 0600.
> I open this file as root at the moment. And we can change it back
> if/when we better understand a potential use case.
I think it's safer to make it 0600. It's up to system administrator to
change permissions, if he wants give this capability to mortals.
--
Kirill A. Shutemov
WARNING: multiple messages have this Message-ID (diff)
From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Dmitry Vyukov <dvyukov@google.com>
Cc: syzkaller <syzkaller@googlegroups.com>,
Vegard Nossum <vegard.nossum@oracle.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Tavis Ormandy <taviso@google.com>,
Will Deacon <will.deacon@arm.com>,
LKML <linux-kernel@vger.kernel.org>,
Quentin Casasnovas <quentin.casasnovas@oracle.com>,
Kostya Serebryany <kcc@google.com>,
Eric Dumazet <edumazet@google.com>,
Alexander Potapenko <glider@google.com>,
Kees Cook <keescook@google.com>,
Bjorn Helgaas <bhelgaas@google.com>,
Sasha Levin <sasha.levin@oracle.com>,
Andrew Morton <akpm@linux-foundation.org>,
David Drysdale <drysdale@google.com>,
linux-arm-kernel@lists.infradead.org,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Andrey Ryabinin <ryabinin.a.a@gmail.com>
Subject: Re: [PATCH v4] kernel: add kcov code coverage
Date: Tue, 19 Jan 2016 15:05:43 +0200 [thread overview]
Message-ID: <20160119130543.GB20984@node.shutemov.name> (raw)
In-Reply-To: <CACT4Y+ZUKJOmATAASxM1qnbn=_0M9TAtTQYO0ecMtursLYvdww@mail.gmail.com>
On Tue, Jan 19, 2016 at 01:55:43PM +0100, Dmitry Vyukov wrote:
> >> +static int __init kcov_init(void)
> >> +{
> >> + if (!debugfs_create_file("kcov", 0666, NULL, NULL, &kcov_fops)) {
> >
> > Why 0666? May be 0600?.
>
> The idea is that it can be useful to fuzz-test under a normal user as well.
> This file is also guarded by debugfs mount permissions. Usually it is mounted
> as 0700, so normal users can't get access to it.
> However if one wants to fuzz-test under a normal user, he could mount
> debugfs as 0777 and get access to this file.
>
> I am not very strong about this, though. If you say, I will change it to 0600.
> I open this file as root at the moment. And we can change it back
> if/when we better understand a potential use case.
I think it's safer to make it 0600. It's up to system administrator to
change permissions, if he wants give this capability to mortals.
--
Kirill A. Shutemov
next prev parent reply other threads:[~2016-01-19 13:05 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-18 19:25 [PATCH v4] kernel: add kcov code coverage Dmitry Vyukov
2016-01-18 19:25 ` Dmitry Vyukov
2016-01-18 22:55 ` Kirill A. Shutemov
2016-01-18 22:55 ` Kirill A. Shutemov
2016-01-19 12:55 ` Dmitry Vyukov
2016-01-19 12:55 ` Dmitry Vyukov
2016-01-19 13:05 ` Kirill A. Shutemov [this message]
2016-01-19 13:05 ` Kirill A. Shutemov
2016-01-19 14:02 ` Dmitry Vyukov
2016-01-19 14:02 ` Dmitry Vyukov
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