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Message-ID: <CALCETrXMgx+pFsL-5s6jRHxsTCJk8U8f5AFMzchsy_L6DyMAvQ@mail.gmail.com>
Date: Fri, 12 May 2017 16:20:31 -0700
From: Andy Lutomirski <luto@...nel.org>
To: Al Viro <viro@...iv.linux.org.uk>
Cc: Ingo Molnar <mingo@...nel.org>, Andy Lutomirski <luto@...nel.org>,
Christoph Hellwig <hch@...radead.org>, Greg KH <greg@...ah.com>, Thomas Garnier <thgarnie@...gle.com>,
Martin Schwidefsky <schwidefsky@...ibm.com>, Heiko Carstens <heiko.carstens@...ibm.com>,
Dave Hansen <dave.hansen@...el.com>, Arnd Bergmann <arnd@...db.de>,
Thomas Gleixner <tglx@...utronix.de>, David Howells <dhowells@...hat.com>,
René Nyffenegger <mail@...enyffenegger.ch>,
Andrew Morton <akpm@...ux-foundation.org>,
"Paul E . McKenney" <paulmck@...ux.vnet.ibm.com>, "Eric W . Biederman" <ebiederm@...ssion.com>,
Oleg Nesterov <oleg@...hat.com>, Pavel Tikhomirov <ptikhomirov@...tuozzo.com>,
Ingo Molnar <mingo@...hat.com>, "H . Peter Anvin" <hpa@...or.com>, Paolo Bonzini <pbonzini@...hat.com>,
Rik van Riel <riel@...hat.com>, Kees Cook <keescook@...omium.org>,
Josh Poimboeuf <jpoimboe@...hat.com>, Borislav Petkov <bp@...en8.de>, Brian Gerst <brgerst@...il.com>,
"Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
Christian Borntraeger <borntraeger@...ibm.com>, Russell King <linux@...linux.org.uk>,
Will Deacon <will.deacon@....com>, Catalin Marinas <catalin.marinas@....com>,
Mark Rutland <mark.rutland@....com>, James Morse <james.morse@....com>,
linux-s390 <linux-s390@...r.kernel.org>, LKML <linux-kernel@...r.kernel.org>,
Linux API <linux-api@...r.kernel.org>, "the arch/x86 maintainers" <x86@...nel.org>,
"linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>,
Kernel Hardening <kernel-hardening@...ts.openwall.com>,
Linus Torvalds <torvalds@...ux-foundation.org>, Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: Re: [PATCH v9 1/4] syscalls: Verify address
limit before returning to user-mode
On Fri, May 12, 2017 at 12:15 AM, Al Viro <viro@...iv.linux.org.uk> wrote:
> Folks, seriously, have you even looked through that zoo? I have, and it's
> really, really not fun. Sure, we can say "fuck 'em, no need to allow
> splice() on random crap". Would be perfectly reasonable, expect that
> it's not the only place doing kernel_write() and its ilk...
Can you clarify this? I think we really may be able to do exactly
this. From Christoph's list, there are only two things that need
kernel_read/kernel_write to user-supplied fds that may come from a
variety of sources: splice and exec. If you're execing a chardev from
a crappy driver, something is seriously wrong. And returning -EINVAL
from splice() to or from files that use ->read and ->write seems find
(and splice(2) even documents -EINVAL as meaning that the target
doesn't support splicing).
--Andy
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