Date: Wed, 10 May 2017 00:35:34 -0700 From: Christoph Hellwig <hch@...radead.org> To: Al Viro <viro@...IV.linux.org.uk> Cc: Christoph Hellwig <hch@...radead.org>, Andy Lutomirski <luto@...nel.org>, Ingo Molnar <mingo@...nel.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 Wed, May 10, 2017 at 08:27:47AM +0100, Al Viro wrote: > And you *still* do the same. Christoph, this is ridiculous - the worst > part of the area is not a couple of functions in fs/read_write.c, it's > a fucking lot of ->read() and ->write() instances in shitty driver code, > pardon the redundance. And _that_ is still done under set_fs(KERNEL_DS). For now yes. But it provides a sane API on top, and then we can start moving the drivers that matter to the iter variants and drop support for the rest soon. Most in-kernel I/O is done to files, and the rest to a very limited set of devices. (not accounting for sockets through their own APIs, thats another story) > That's what I'm objecting to. Centralized kernel_readv() et.al. - sure, > and fs/read_write.c is the right place for those. No arguments here. > Conversion to those - absolutely; drivers have no fucking business touching > set_fs() at all. But your primitives are trouble waiting to happen. > Let them take kvec arrays. And let them, in case when there's no > ->read_iter()/->write_iter(), do set_fs(). Statically, without this > if (iter->type & ITER_KVEC) ... stuff. Oh weĺl. I can do that first, but I think eventually we'll have to get back to what I've done now.
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