From patchwork Thu Jan 23 12:59:54 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christophe Leroy X-Patchwork-Id: 11347745 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 5441092A for ; Thu, 23 Jan 2020 13:00:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2991724688 for ; Thu, 23 Jan 2020 13:00:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=c-s.fr header.i=@c-s.fr header.b="m8vT+7Vj" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729058AbgAWNAS (ORCPT ); Thu, 23 Jan 2020 08:00:18 -0500 Received: from pegase1.c-s.fr ([93.17.236.30]:60517 "EHLO pegase1.c-s.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726605AbgAWM75 (ORCPT ); Thu, 23 Jan 2020 07:59:57 -0500 Received: from localhost (mailhub1-int [192.168.12.234]) by localhost (Postfix) with ESMTP id 483Mn554fPz9vB4b; Thu, 23 Jan 2020 13:59:53 +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=m8vT+7Vj; 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 ODcJLQQ8KZdO; Thu, 23 Jan 2020 13:59:53 +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 483Mn53tM9z9vB4X; Thu, 23 Jan 2020 13:59:53 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=c-s.fr; s=mail; t=1579784393; bh=2A+DHD4btbFKfkOs6li2k01GNKK7HnJcrGNXJq6nAh4=; h=In-Reply-To:References:From:Subject:To:Cc:Date:From; b=m8vT+7VjBVWNki/Oeh7C7BbraLtfYVArr703qXZL5c2vj5AWSKxjwCbz9BtuuyWR1 GBQQZ9vzCgDZPZeTu8eiNjIm54B1gFVifdKLURdmXWV1lTt4RBeAY8pYc5TPPIEmqf t9E+BFoZEi62/xolOq+fMXM7cb68oLHKfK+h+guE= Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id B4F0D8B82E; Thu, 23 Jan 2020 13:59:54 +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 kZ62ky9AMEwp; Thu, 23 Jan 2020 13:59:54 +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 714C98B826; Thu, 23 Jan 2020 13:59:54 +0100 (CET) Received: by po14934vm.idsi0.si.c-s.fr (Postfix, from userid 0) id 44CEB651C0; Thu, 23 Jan 2020 12:59:54 +0000 (UTC) Message-Id: <584ce843dc9d1982934c2b64dd9e64f21ac84c9a.1579783936.git.christophe.leroy@c-s.fr> In-Reply-To: References: From: Christophe Leroy Subject: [PATCH v3 3/7] powerpc/32s: Fix bad_kuap_fault() 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: Thu, 23 Jan 2020 12:59:54 +0000 (UTC) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org At the moment, bad_kuap_fault() reports a fault only if a bad access to userspace occurred while access to userspace was not granted. But if a fault occurs for a write outside the allowed userspace segment(s) that have been unlocked, bad_kuap_fault() fails to detect it and the kernel loops forever in do_page_fault(). Fix it by checking that the accessed address is within the allowed range. Fixes: a68c31fc01ef ("powerpc/32s: Implement Kernel Userspace Access Protection") Cc: stable@vger.kernel.org Signed-off-by: Christophe Leroy --- v2: added missing address parametre to bad_kuap_fault() in asm/kup.h v3: no change --- arch/powerpc/include/asm/book3s/32/kup.h | 9 +++++++-- arch/powerpc/include/asm/book3s/64/kup-radix.h | 3 ++- arch/powerpc/include/asm/kup.h | 6 +++++- arch/powerpc/include/asm/nohash/32/kup-8xx.h | 3 ++- arch/powerpc/mm/fault.c | 2 +- 5 files changed, 17 insertions(+), 6 deletions(-) diff --git a/arch/powerpc/include/asm/book3s/32/kup.h b/arch/powerpc/include/asm/book3s/32/kup.h index f9dc597b0b86..d88008c8eb85 100644 --- a/arch/powerpc/include/asm/book3s/32/kup.h +++ b/arch/powerpc/include/asm/book3s/32/kup.h @@ -131,12 +131,17 @@ static inline void prevent_user_access(void __user *to, const void __user *from, kuap_update_sr(mfsrin(addr) | SR_KS, addr, end); /* set Ks */ } -static inline bool bad_kuap_fault(struct pt_regs *regs, bool is_write) +static inline bool +bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write) { + unsigned long begin = regs->kuap & 0xf0000000; + unsigned long end = regs->kuap << 28; + if (!is_write) return false; - return WARN(!regs->kuap, "Bug: write fault blocked by segment registers !"); + return WARN(address < begin || address >= end, + "Bug: write fault blocked by segment registers !"); } #endif /* CONFIG_PPC_KUAP */ diff --git a/arch/powerpc/include/asm/book3s/64/kup-radix.h b/arch/powerpc/include/asm/book3s/64/kup-radix.h index f254de956d6a..dbbd22cb80f5 100644 --- a/arch/powerpc/include/asm/book3s/64/kup-radix.h +++ b/arch/powerpc/include/asm/book3s/64/kup-radix.h @@ -95,7 +95,8 @@ static inline void prevent_user_access(void __user *to, const void __user *from, set_kuap(AMR_KUAP_BLOCKED); } -static inline bool bad_kuap_fault(struct pt_regs *regs, bool is_write) +static inline bool +bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write) { return WARN(mmu_has_feature(MMU_FTR_RADIX_KUAP) && (regs->kuap & (is_write ? AMR_KUAP_BLOCK_WRITE : AMR_KUAP_BLOCK_READ)), diff --git a/arch/powerpc/include/asm/kup.h b/arch/powerpc/include/asm/kup.h index 5b5e39643a27..812e66f31934 100644 --- a/arch/powerpc/include/asm/kup.h +++ b/arch/powerpc/include/asm/kup.h @@ -45,7 +45,11 @@ static inline void allow_user_access(void __user *to, const void __user *from, unsigned long size) { } static inline void prevent_user_access(void __user *to, const void __user *from, unsigned long size) { } -static inline bool bad_kuap_fault(struct pt_regs *regs, bool is_write) { return false; } +static inline bool +bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write) +{ + return false; +} #endif /* CONFIG_PPC_KUAP */ static inline void allow_read_from_user(const void __user *from, unsigned long size) diff --git a/arch/powerpc/include/asm/nohash/32/kup-8xx.h b/arch/powerpc/include/asm/nohash/32/kup-8xx.h index 1006a427e99c..f2fea603b929 100644 --- a/arch/powerpc/include/asm/nohash/32/kup-8xx.h +++ b/arch/powerpc/include/asm/nohash/32/kup-8xx.h @@ -46,7 +46,8 @@ static inline void prevent_user_access(void __user *to, const void __user *from, mtspr(SPRN_MD_AP, MD_APG_KUAP); } -static inline bool bad_kuap_fault(struct pt_regs *regs, bool is_write) +static inline bool +bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write) { return WARN(!((regs->kuap ^ MD_APG_KUAP) & 0xf0000000), "Bug: fault blocked by AP register !"); diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c index b5047f9b5dec..1baeb045f7f4 100644 --- a/arch/powerpc/mm/fault.c +++ b/arch/powerpc/mm/fault.c @@ -233,7 +233,7 @@ static bool bad_kernel_fault(struct pt_regs *regs, unsigned long error_code, // Read/write fault in a valid region (the exception table search passed // above), but blocked by KUAP is bad, it can never succeed. - if (bad_kuap_fault(regs, is_write)) + if (bad_kuap_fault(regs, address, is_write)) return true; // What's left? Kernel fault on user in well defined regions (extable