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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,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 6370DC433DB for ; Wed, 31 Mar 2021 10:40:18 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id F180760C41 for ; Wed, 31 Mar 2021 10:40:16 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org F180760C41 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=csgroup.eu Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4F9NB71m7Nz3c2s for ; Wed, 31 Mar 2021 21:40:15 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=csgroup.eu (client-ip=93.17.236.30; helo=pegase1.c-s.fr; envelope-from=christophe.leroy@csgroup.eu; receiver=) Received: from pegase1.c-s.fr (pegase1.c-s.fr [93.17.236.30]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4F9N9j02Yrz3bpJ for ; Wed, 31 Mar 2021 21:39:49 +1100 (AEDT) Received: from localhost (mailhub1-int [192.168.12.234]) by localhost (Postfix) with ESMTP id 4F9N9Y24GNz9ty3J; Wed, 31 Mar 2021 12:39:45 +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 vFTVnU7cHPI7; Wed, 31 Mar 2021 12:39:45 +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 4F9N9Y1DWsz9ty2t; Wed, 31 Mar 2021 12:39:45 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 338BD8B7FB; Wed, 31 Mar 2021 12:39:46 +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 DmOfJZKq4OBf; Wed, 31 Mar 2021 12:39:46 +0200 (CEST) Received: from [192.168.4.90] (unknown [192.168.4.90]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 7CEB68B75B; Wed, 31 Mar 2021 12:39:45 +0200 (CEST) Subject: Re: [PATCH v10 05/10] powerpc/bpf: Write protect JIT code To: Michael Ellerman , Jordan Niethe , linuxppc-dev@lists.ozlabs.org References: <20210330045132.722243-1-jniethe5@gmail.com> <20210330045132.722243-6-jniethe5@gmail.com> <87wntnwqw9.fsf@mpe.ellerman.id.au> From: Christophe Leroy Message-ID: <9034d909-170f-7e9c-02a2-e329d613ed7c@csgroup.eu> Date: Wed, 31 Mar 2021 12:39:44 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.9.0 MIME-Version: 1.0 In-Reply-To: <87wntnwqw9.fsf@mpe.ellerman.id.au> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: fr Content-Transfer-Encoding: 8bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: naveen.n.rao@linux.ibm.com, cmr@codefail.de, ajd@linux.ibm.com, npiggin@gmail.com, dja@axtens.net Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Le 31/03/2021 à 12:37, Michael Ellerman a écrit : > Jordan Niethe writes: > >> Once CONFIG_STRICT_MODULE_RWX is enabled there will be no need to >> override bpf_jit_free() because it is now possible to set images >> read-only. So use the default implementation. >> >> Also add the necessary call to bpf_jit_binary_lock_ro() which will >> remove write protection and add exec protection to the JIT image after >> it has finished being written. >> >> Signed-off-by: Jordan Niethe >> --- >> v10: New to series >> --- >> arch/powerpc/net/bpf_jit_comp.c | 5 ++++- >> arch/powerpc/net/bpf_jit_comp64.c | 4 ++++ >> 2 files changed, 8 insertions(+), 1 deletion(-) >> >> diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c >> index e809cb5a1631..8015e4a7d2d4 100644 >> --- a/arch/powerpc/net/bpf_jit_comp.c >> +++ b/arch/powerpc/net/bpf_jit_comp.c >> @@ -659,12 +659,15 @@ void bpf_jit_compile(struct bpf_prog *fp) >> bpf_jit_dump(flen, proglen, pass, code_base); >> >> bpf_flush_icache(code_base, code_base + (proglen/4)); >> - >> #ifdef CONFIG_PPC64 >> /* Function descriptor nastiness: Address + TOC */ >> ((u64 *)image)[0] = (u64)code_base; >> ((u64 *)image)[1] = local_paca->kernel_toc; >> #endif >> + if (IS_ENABLED(CONFIG_STRICT_MODULE_RWX)) { >> + set_memory_ro((unsigned long)image, alloclen >> PAGE_SHIFT); >> + set_memory_x((unsigned long)image, alloclen >> PAGE_SHIFT); >> + } > > You don't need to check the ifdef in a caller, there are stubs that > compile to nothing when CONFIG_ARCH_HAS_SET_MEMORY=n. I was about to do the same comment, but .... CONFIG_STRICT_MODULE_RWX is not CONFIG_ARCH_HAS_SET_MEMORY > >> diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c >> index aaf1a887f653..1484ad588685 100644 >> --- a/arch/powerpc/net/bpf_jit_comp64.c >> +++ b/arch/powerpc/net/bpf_jit_comp64.c >> @@ -1240,6 +1240,8 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp) >> fp->jited_len = alloclen; >> >> bpf_flush_icache(bpf_hdr, (u8 *)bpf_hdr + (bpf_hdr->pages * PAGE_SIZE)); >> + if (IS_ENABLED(CONFIG_STRICT_MODULE_RWX)) >> + bpf_jit_binary_lock_ro(bpf_hdr); > > Do we need the ifdef here either? Looks like it should be safe to call > due to the stubs. Same > >> @@ -1262,6 +1264,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp) >> } >> >> /* Overriding bpf_jit_free() as we don't set images read-only. */ >> +#ifndef CONFIG_STRICT_MODULE_RWX > > Did you test without this and notice something broken? > > Looking at the generic version I can't tell why we need to override > this. Maybe we don't (anymore?) ? > > cheers > >> void bpf_jit_free(struct bpf_prog *fp) >> { >> unsigned long addr = (unsigned long)fp->bpf_func & PAGE_MASK; >> @@ -1272,3 +1275,4 @@ void bpf_jit_free(struct bpf_prog *fp) >> >> bpf_prog_unlock_free(fp); >> } >> +#endif >> -- >> 2.25.1