From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-11.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EADEFC433E2 for ; Wed, 2 Sep 2020 06:15:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D3E45206C0 for ; Wed, 2 Sep 2020 06:15:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726510AbgIBGPZ (ORCPT ); Wed, 2 Sep 2020 02:15:25 -0400 Received: from pegase1.c-s.fr ([93.17.236.30]:50693 "EHLO pegase1.c-s.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726144AbgIBGPY (ORCPT ); Wed, 2 Sep 2020 02:15:24 -0400 Received: from localhost (mailhub1-int [192.168.12.234]) by localhost (Postfix) with ESMTP id 4BhDFM1jjKz9tyTH; Wed, 2 Sep 2020 08:15:19 +0200 (CEST) X-Virus-Scanned: Debian amavisd-new at c-s.fr Received: from pegase1.c-s.fr ([192.168.12.234]) by localhost (pegase1.c-s.fr [192.168.12.234]) (amavisd-new, port 10024) with ESMTP id 3We4wFWomQ2D; Wed, 2 Sep 2020 08:15:19 +0200 (CEST) Received: from messagerie.si.c-s.fr (messagerie.si.c-s.fr [192.168.25.192]) by pegase1.c-s.fr (Postfix) with ESMTP id 4BhDFM0fQQz9tyTG; Wed, 2 Sep 2020 08:15:19 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 111128B788; Wed, 2 Sep 2020 08:15:20 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id bC4OSETSJupy; Wed, 2 Sep 2020 08:15:19 +0200 (CEST) Received: from [10.25.210.31] (unknown [10.25.210.31]) by messagerie.si.c-s.fr (Postfix) with ESMTP id C01518B784; Wed, 2 Sep 2020 08:15:19 +0200 (CEST) Subject: Re: [PATCH 10/10] powerpc: remove address space overrides using set_fs() To: Christoph Hellwig , Linus Torvalds , Al Viro , Michael Ellerman , x86@kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, Kees Cook , linux-kernel@vger.kernel.org References: <20200827150030.282762-1-hch@lst.de> <20200827150030.282762-11-hch@lst.de> From: Christophe Leroy Message-ID: <8974838a-a0b1-1806-4a3a-e983deda67ca@csgroup.eu> Date: Wed, 2 Sep 2020 08:15:12 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: <20200827150030.282762-11-hch@lst.de> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: fr Content-Transfer-Encoding: 8bit Sender: linux-arch-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-arch@vger.kernel.org Le 27/08/2020 à 17:00, Christoph Hellwig a écrit : > Stop providing the possibility to override the address space using > set_fs() now that there is no need for that any more. > > Signed-off-by: Christoph Hellwig > --- > arch/powerpc/Kconfig | 1 - > arch/powerpc/include/asm/processor.h | 7 --- > arch/powerpc/include/asm/thread_info.h | 5 +-- > arch/powerpc/include/asm/uaccess.h | 62 ++++++++------------------ > arch/powerpc/kernel/signal.c | 3 -- > arch/powerpc/lib/sstep.c | 6 +-- > 6 files changed, 22 insertions(+), 62 deletions(-) > > diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h > index 7fe3531ad36a77..39727537d39701 100644 > --- a/arch/powerpc/include/asm/uaccess.h > +++ b/arch/powerpc/include/asm/uaccess.h > @@ -8,62 +8,36 @@ > #include > #include > > -/* > - * The fs value determines whether argument validity checking should be > - * performed or not. If get_fs() == USER_DS, checking is performed, with > - * get_fs() == KERNEL_DS, checking is bypassed. > - * > - * For historical reasons, these macros are grossly misnamed. > - * > - * The fs/ds values are now the highest legal address in the "segment". > - * This simplifies the checking in the routines below. > - */ > - > -#define MAKE_MM_SEG(s) ((mm_segment_t) { (s) }) > - > -#define KERNEL_DS MAKE_MM_SEG(~0UL) > #ifdef __powerpc64__ > /* We use TASK_SIZE_USER64 as TASK_SIZE is not constant */ > -#define USER_DS MAKE_MM_SEG(TASK_SIZE_USER64 - 1) > -#else > -#define USER_DS MAKE_MM_SEG(TASK_SIZE - 1) > -#endif > - > -#define get_fs() (current->thread.addr_limit) > +#define TASK_SIZE_MAX TASK_SIZE_USER64 > > -static inline void set_fs(mm_segment_t fs) > +static inline bool __access_ok(unsigned long addr, unsigned long size) > { > - current->thread.addr_limit = fs; > - /* On user-mode return check addr_limit (fs) is correct */ > - set_thread_flag(TIF_FSCHECK); > + if (addr >= TASK_SIZE_MAX) > + return false; > + /* > + * This check is sufficient because there is a large enough gap between > + * user addresses and the kernel addresses. > + */ > + return size <= TASK_SIZE_MAX; > } > - > -#define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg) > -#define user_addr_max() (get_fs().seg) > - > -#ifdef __powerpc64__ > -/* > - * This check is sufficient because there is a large enough > - * gap between user addresses and the kernel addresses > - */ > -#define __access_ok(addr, size, segment) \ > - (((addr) <= (segment).seg) && ((size) <= (segment).seg)) > - > #else > +#define TASK_SIZE_MAX TASK_SIZE > > -static inline int __access_ok(unsigned long addr, unsigned long size, > - mm_segment_t seg) > +static inline bool __access_ok(unsigned long addr, unsigned long size) > { > - if (addr > seg.seg) > - return 0; > - return (size == 0 || size - 1 <= seg.seg - addr); > + if (addr >= TASK_SIZE_MAX) > + return false; > + if (size == 0) > + return false; __access_ok() was returning true when size == 0 up to now. Any reason to return false now ? > + return size <= TASK_SIZE_MAX - addr; > } > - > -#endif > +#endif /* __powerpc64__ */ > > #define access_ok(addr, size) \ > (__chk_user_ptr(addr), \ > - __access_ok((__force unsigned long)(addr), (size), get_fs())) > + __access_ok((unsigned long)(addr), (size))) > > /* > * These are the main single-value transfer routines. They automatically Christophe