From patchwork Wed Jan 22 17:52:51 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christophe Leroy X-Patchwork-Id: 11346217 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 978E092A for ; Wed, 22 Jan 2020 17:53:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7614D2465A for ; Wed, 22 Jan 2020 17:53:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=c-s.fr header.i=@c-s.fr header.b="qkN85J/J" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729083AbgAVRwz (ORCPT ); Wed, 22 Jan 2020 12:52:55 -0500 Received: from pegase1.c-s.fr ([93.17.236.30]:4045 "EHLO pegase1.c-s.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725883AbgAVRwy (ORCPT ); Wed, 22 Jan 2020 12:52:54 -0500 Received: from localhost (mailhub1-int [192.168.12.234]) by localhost (Postfix) with ESMTP id 482tKZ4Mjhz9vBmj; Wed, 22 Jan 2020 18:52:50 +0100 (CET) Authentication-Results: localhost; dkim=pass reason="1024-bit key; insecure key" header.d=c-s.fr header.i=@c-s.fr header.b=qkN85J/J; dkim-adsp=pass; dkim-atps=neutral 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 G2ifJQ-r2Ov6; Wed, 22 Jan 2020 18:52:50 +0100 (CET) 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 482tKZ3FV0z9vBf1; Wed, 22 Jan 2020 18:52:50 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=c-s.fr; s=mail; t=1579715570; bh=8dizNlmXa18nvxrEuEdmfsHiWWHIwWhz4sd63oYOH1M=; h=In-Reply-To:References:From:Subject:To:Cc:Date:From; b=qkN85J/J4f24fMTGQqzRMSxhPlbRBM87KY1WY1BCFViZW/pK4PZItQZFf8zrCuUt9 kohquxPCVJkomgfZ6jp7fb8O70vVeyERCKclSwTCI0Y+pbbnihwATZqev5G0O/8JV3 kEslOIxA5EMMOY4eT9zoXQlS+QXFEHnAqa/PEQ+k= Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 29D548B810; Wed, 22 Jan 2020 18:52:52 +0100 (CET) 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 rTomGVjtT7Og; Wed, 22 Jan 2020 18:52:52 +0100 (CET) Received: from po14934vm.idsi0.si.c-s.fr (unknown [192.168.4.90]) by messagerie.si.c-s.fr (Postfix) with ESMTP id E55738B7FE; Wed, 22 Jan 2020 18:52:51 +0100 (CET) Received: by localhost.localdomain (Postfix, from userid 0) id BE563651E0; Wed, 22 Jan 2020 17:52:51 +0000 (UTC) Message-Id: <824b69f5452d1d41d12c4dbd306d4b8f32d493fc.1579715466.git.christophe.leroy@c-s.fr> In-Reply-To: <12a4be679e43de1eca6e5e2173163f27e2f25236.1579715466.git.christophe.leroy@c-s.fr> References: <12a4be679e43de1eca6e5e2173163f27e2f25236.1579715466.git.christophe.leroy@c-s.fr> From: Christophe Leroy Subject: [PATCH v2 5/6] powerpc/32s: prepare prevent_user_access() for user_access_end() To: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Date: Wed, 22 Jan 2020 17:52:51 +0000 (UTC) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org In preparation of implementing user_access_begin and friends on powerpc, the book3s/32 version of prevent_user_access() need to be prepared for user_access_end(). user_access_end() doesn't provide the address and size which were passed to user_access_begin(), required by prevent_user_access() to know which segment to modify. The list of segments which where unprotected by allow_user_access() are available in current->kuap. But we don't want prevent_user_access() to read this all the time, especially everytime it is 0 (for instance because the access was not a write access). Implement a special direction case named KUAP_SELF. In this case only, the addr and end are retrieved from current->kuap. Signed-off-by: Christophe Leroy --- v2: no change --- arch/powerpc/include/asm/book3s/32/kup.h | 25 ++++++++++++++++++------ arch/powerpc/include/asm/kup.h | 1 + 2 files changed, 20 insertions(+), 6 deletions(-) diff --git a/arch/powerpc/include/asm/book3s/32/kup.h b/arch/powerpc/include/asm/book3s/32/kup.h index 3c1798e56b55..a99fc3428ac9 100644 --- a/arch/powerpc/include/asm/book3s/32/kup.h +++ b/arch/powerpc/include/asm/book3s/32/kup.h @@ -117,6 +117,7 @@ static __always_inline void allow_user_access(void __user *to, const void __user return; end = min(addr + size, TASK_SIZE); + current->thread.kuap = (addr & 0xf0000000) | ((((end - 1) >> 28) + 1) & 0xf); kuap_update_sr(mfsrin(addr) & ~SR_KS, addr, end); /* Clear Ks */ } @@ -127,15 +128,27 @@ static __always_inline void prevent_user_access(void __user *to, const void __us u32 addr, end; BUILD_BUG_ON(!__builtin_constant_p(dir)); - if (!(dir & KUAP_W)) - return; - addr = (__force u32)to; + if (dir == KUAP_SELF) { + u32 kuap = current->thread.kuap; - if (unlikely(addr >= TASK_SIZE || !size)) - return; + if (unlikely(!kuap)) + return; + + addr = kuap & 0xf0000000; + end = kuap << 28; + } else { + if (!(dir & KUAP_W)) + return; + + addr = (__force u32)to; + + if (unlikely(addr >= TASK_SIZE || !size)) + return; + + end = min(addr + size, TASK_SIZE); + } - end = min(addr + size, TASK_SIZE); current->thread.kuap = 0; kuap_update_sr(mfsrin(addr) | SR_KS, addr, end); /* set Ks */ } diff --git a/arch/powerpc/include/asm/kup.h b/arch/powerpc/include/asm/kup.h index ff57bfcb88f7..4229e749dcf4 100644 --- a/arch/powerpc/include/asm/kup.h +++ b/arch/powerpc/include/asm/kup.h @@ -5,6 +5,7 @@ #define KUAP_R 1 #define KUAP_W 2 #define KUAP_RW (KUAP_R | KUAP_W) +#define KUAP_SELF 4 #ifdef CONFIG_PPC64 #include