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=-10.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 12A94C388F9 for ; Tue, 27 Oct 2020 10:46:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B6C2520878 for ; Tue, 27 Oct 2020 10:46:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603795583; bh=BWEogo4zan460Xro77zd5zdnFTbhvlZs3lArxt9EbMU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=NFC2XnvzFtyYXYd3W6E0eko7dkyI0DK4+o2N+2EttrRk1xz6+gdBul2yCczddN2Cn BIyaDx4Guo4WzGbtSACS2XEFdrNaJtIRN1fKfAYnYSKIWWb/B/Al+EazUOLqdyR+Xv ztrvFpG6yO07lQ0gV9rUQBXK12nSkGNzVrjLHbZw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1418542AbgJ0KqU (ORCPT ); Tue, 27 Oct 2020 06:46:20 -0400 Received: from mail.kernel.org ([198.145.29.99]:35774 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1418381AbgJ0Kpy (ORCPT ); Tue, 27 Oct 2020 06:45:54 -0400 Received: from kernel.org (unknown [87.70.96.83]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 5720420878; Tue, 27 Oct 2020 10:45:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603795553; bh=BWEogo4zan460Xro77zd5zdnFTbhvlZs3lArxt9EbMU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Wr5+aTzwxMIQo7avnuGP+/bdQzYn0kB+wmrSHlTAAGIjNgJIuP41vmOFMzcxLcovh KCbJ4RVls6C1pu0jvsh3B9qqXcWVtmGdXenwIXEItvxu37lLmgr2HCpaqYTphCpNcR fLs1WqZ0A6xplkWWPtpxQVX4+ZOFSUxZ4+ncVqS8= Date: Tue, 27 Oct 2020 12:45:45 +0200 From: Mike Rapoport To: Atish Patra Cc: linux-kernel@vger.kernel.org, Albert Ou , Andrew Morton , Anup Patel , Ard Biesheuvel , Borislav Petkov , Greentime Hu , Kees Cook , linux-riscv@lists.infradead.org, Michel Lespinasse , Palmer Dabbelt , Paul Walmsley , Zong Li Subject: Re: [PATCH v2 5/6] RISC-V: Protect .init.text & .init.data Message-ID: <20201027104545.GM1154158@kernel.org> References: <20201026230254.911912-1-atish.patra@wdc.com> <20201026230254.911912-6-atish.patra@wdc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201026230254.911912-6-atish.patra@wdc.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Oct 26, 2020 at 04:02:53PM -0700, Atish Patra wrote: > Currently, .init.text & .init.data are intermixed which makes it impossible > apply different permissions to them. .init.data shouldn't need exec > permissions while .init.text shouldn't have write permission. > > Keep them in separate sections so that different permissions are applied to > each section. This improves the kernel protection under > CONFIG_STRICT_KERNEL_RWX. We also need to restore the permissions for the > entire _init section after it is freed so that those pages can be used for > other purpose. > > Signed-off-by: Atish Patra > --- > arch/riscv/include/asm/sections.h | 2 ++ > arch/riscv/include/asm/set_memory.h | 2 ++ > arch/riscv/kernel/setup.c | 9 +++++ > arch/riscv/kernel/vmlinux.lds.S | 51 ++++++++++++++++------------- > arch/riscv/mm/init.c | 8 ++++- > arch/riscv/mm/pageattr.c | 6 ++++ > 6 files changed, 54 insertions(+), 24 deletions(-) > > diff --git a/arch/riscv/include/asm/sections.h b/arch/riscv/include/asm/sections.h > index 3a9971b1210f..1595c5b60cfd 100644 > --- a/arch/riscv/include/asm/sections.h > +++ b/arch/riscv/include/asm/sections.h > @@ -9,5 +9,7 @@ > > extern char _start[]; > extern char _start_kernel[]; > +extern char __init_data_begin[], __init_data_end[]; > +extern char __init_text_begin[], __init_text_end[]; > > #endif /* __ASM_SECTIONS_H */ > diff --git a/arch/riscv/include/asm/set_memory.h b/arch/riscv/include/asm/set_memory.h > index 4cc3a4e2afd3..913429c9c1ae 100644 > --- a/arch/riscv/include/asm/set_memory.h > +++ b/arch/riscv/include/asm/set_memory.h > @@ -15,6 +15,7 @@ int set_memory_ro(unsigned long addr, int numpages); > int set_memory_rw(unsigned long addr, int numpages); > int set_memory_x(unsigned long addr, int numpages); > int set_memory_nx(unsigned long addr, int numpages); > +int set_memory_default(unsigned long addr, int numpages); > void protect_kernel_text_data(void); > #else > static inline int set_memory_ro(unsigned long addr, int numpages) { return 0; } > @@ -22,6 +23,7 @@ static inline int set_memory_rw(unsigned long addr, int numpages) { return 0; } > static inline int set_memory_x(unsigned long addr, int numpages) { return 0; } > static inline int set_memory_nx(unsigned long addr, int numpages) { return 0; } > static inline void protect_kernel_text_data(void) {}; > +static inline int set_memory_default(unsigned long addr, int numpages) { return 0; } > #endif > > int set_direct_map_invalid_noflush(struct page *page); > diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c > index b722c5bf892c..abfbdc8cfef3 100644 > --- a/arch/riscv/kernel/setup.c > +++ b/arch/riscv/kernel/setup.c > @@ -123,3 +123,12 @@ static int __init topology_init(void) > return 0; > } > subsys_initcall(topology_init); > + > +void free_initmem(void) > +{ > + unsigned long init_begin = (unsigned long)__init_begin; > + unsigned long init_end = (unsigned long)__init_end; > + > + set_memory_default(init_begin, (init_end - init_begin) >> PAGE_SHIFT); And what does "default" imply? Maybe set_memory_rw() would better name ... > + free_initmem_default(POISON_FREE_INITMEM); > +} ... > diff --git a/arch/riscv/mm/pageattr.c b/arch/riscv/mm/pageattr.c > index 19fecb362d81..04f3fc16aa9c 100644 > --- a/arch/riscv/mm/pageattr.c > +++ b/arch/riscv/mm/pageattr.c > @@ -128,6 +128,12 @@ static int __set_memory(unsigned long addr, int numpages, pgprot_t set_mask, > return ret; > } > > +int set_memory_default(unsigned long addr, int numpages) > +{ > + return __set_memory(addr, numpages, __pgprot(_PAGE_KERNEL), > + __pgprot(_PAGE_EXEC)); ... because you'd need to find what _PAGE_KERNEL is, do bitwise ops and than find out that default is apparently RW :) > +} > + > int set_memory_ro(unsigned long addr, int numpages) > { > return __set_memory(addr, numpages, __pgprot(_PAGE_READ), > -- > 2.25.1 > -- Sincerely yours, Mike.