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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 2DE8CC433DF for ; Mon, 8 Jun 2020 09:46:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 12DAC206D5 for ; Mon, 8 Jun 2020 09:46:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729252AbgFHJqq (ORCPT ); Mon, 8 Jun 2020 05:46:46 -0400 Received: from foss.arm.com ([217.140.110.172]:50484 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729166AbgFHJqp (ORCPT ); Mon, 8 Jun 2020 05:46:45 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 16BAF31B; Mon, 8 Jun 2020 02:46:45 -0700 (PDT) Received: from gaia (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 4FC0E3F73D; Mon, 8 Jun 2020 02:46:43 -0700 (PDT) Date: Mon, 8 Jun 2020 10:46:41 +0100 From: Catalin Marinas To: Wang ShaoBo Cc: huawei.libin@huawei.com, cj.chengjian@huawei.com, xiexiuqi@huawei.com, mark.rutland@arm.com, hch@infradead.org, wcohen@redhat.com, linux-kernel@vger.kernel.org, mtk.manpages@gmail.com, wezhang@redhat.com, gregkh@linuxfoundation.org, Will Deacon Subject: Re: [RESEND PATCH] sys_personality: Add optional arch hook arch_check_personality Message-ID: <20200608094640.GA13596@gaia> References: <20200608024925.42510-1-bobo.shaobowang@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200608024925.42510-1-bobo.shaobowang@huawei.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jun 08, 2020 at 10:49:25AM +0800, Wang ShaoBo wrote: > Currently arm64 personality syscall uses wrapper __arm64_sys_personality > to redirect to __arm64_sys_arm64_personality, it's easily confused, > Whereas using an normal hook arch_check_personality() can reject > additional settings like this for special case of different architectures. > > This makes code clean and easier for subsequent modification. Do you plan to add more stuff here? Curious what triggered this patch. > diff --git a/arch/arm64/kernel/sys.c b/arch/arm64/kernel/sys.c > index d5ffaaab31a7..5c01816d7a77 100644 > --- a/arch/arm64/kernel/sys.c > +++ b/arch/arm64/kernel/sys.c > @@ -28,12 +28,13 @@ SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len, > return ksys_mmap_pgoff(addr, len, prot, flags, fd, off >> PAGE_SHIFT); > } > > -SYSCALL_DEFINE1(arm64_personality, unsigned int, personality) > +int arch_check_personality(unsigned int personality) > { > if (personality(personality) == PER_LINUX32 && > !system_supports_32bit_el0()) > return -EINVAL; > - return ksys_personality(personality); > + > + return 0; > } We use the ksys_* pattern in other places as well, so this wouldn't be something new. > diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h > index 1815065d52f3..3dbbad498027 100644 > --- a/include/linux/syscalls.h > +++ b/include/linux/syscalls.h > @@ -1393,16 +1393,6 @@ static inline long ksys_truncate(const char __user *pathname, loff_t length) > return do_sys_truncate(pathname, length); > } > > -static inline unsigned int ksys_personality(unsigned int personality) > -{ > - unsigned int old = current->personality; > - > - if (personality != 0xffffffff) > - set_personality(personality); > - > - return old; > -} > - > /* for __ARCH_WANT_SYS_IPC */ > long ksys_semtimedop(int semid, struct sembuf __user *tsops, > unsigned int nsops, > diff --git a/kernel/exec_domain.c b/kernel/exec_domain.c > index 33f07c5f2515..f3682f4bf205 100644 > --- a/kernel/exec_domain.c > +++ b/kernel/exec_domain.c > @@ -35,9 +35,21 @@ static int __init proc_execdomains_init(void) > module_init(proc_execdomains_init); > #endif > > +int __weak arch_check_personality(unsigned int personality) > +{ > + return 0; > +} > + > SYSCALL_DEFINE1(personality, unsigned int, personality) > { > - unsigned int old = current->personality; > + int err; > + unsigned int old; > + > + err = arch_check_personality(personality); > + if (err) > + return err; > + > + old = current->personality; I'm surprised that the generic sys_personality() doesn't call ksys_personality() directly but rather duplicates the code. Anyway, without knowing what else you plan to do with arch_check_personality(), I don't think it's worth changing. Calling ksys_personality() directly from sys_personality() would be a good clean-up though. -- Catalin