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=-10.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT 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 33A2CC04EB8 for ; Fri, 30 Nov 2018 18:26:35 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 06B0D20673 for ; Fri, 30 Nov 2018 18:26:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="eOkJzBpI" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 06B0D20673 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=gGwvl6mPQPZLr1pqh9+NsxTqM+c+1oPHIT39mm1Xk08=; b=eOkJzBpIUaumqQ 7ladErAkrlF31TpDF+Xm5dBCibh6XSPkmSBAWBpNjQ+PI4uzx9xkt+pMPveuDEuEQyLfxtqoaihB1 rB9MdaXwFCEExy86GmIUo+Xtiq5MnCLubbSzWPVxKX+/DjCqXwzMiSpt36QGnE3mBxlpv+Ydr8J/h h9/hR2zbuoLDc4PPPbqHrIew+lMXyU/c2DFxIanS4SEH9Ic882PG0Jrn7IqSI402rfkJH6jQYc8EX 0H+wHAOYmj3qAZHdO03obrdq8YGQr4Ku/8mTgdhiuWJLPCa6W1+kRJCwh+7omzqA3dmDru/s0v2Ws WkPAaGBOophyArxVlrDQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gSnUh-0001SS-7Q; Fri, 30 Nov 2018 18:26:27 +0000 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70] helo=foss.arm.com) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gSnUd-0001RU-QS for linux-arm-kernel@lists.infradead.org; Fri, 30 Nov 2018 18:26:25 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 129F9165C; Fri, 30 Nov 2018 10:26:11 -0800 (PST) Received: from edgewater-inn.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id D5DA83F575; Fri, 30 Nov 2018 10:26:10 -0800 (PST) Received: by edgewater-inn.cambridge.arm.com (Postfix, from userid 1000) id B8FAC1AE0FA2; Fri, 30 Nov 2018 18:26:29 +0000 (GMT) Date: Fri, 30 Nov 2018 18:26:29 +0000 From: Will Deacon To: Ard Biesheuvel Subject: Re: [PATCH v4 2/2] arm64/bpf: don't allocate BPF JIT programs in module memory Message-ID: <20181130182629.GA16085@arm.com> References: <20181123221804.440-1-ard.biesheuvel@linaro.org> <20181123221804.440-3-ard.biesheuvel@linaro.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20181123221804.440-3-ard.biesheuvel@linaro.org> User-Agent: Mutt/1.5.23 (2014-03-12) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20181130_102623_875768_4F5F1F1D X-CRM114-Status: GOOD ( 23.72 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Daniel Borkmann , Eric Dumazet , Jann Horn , Catalin Marinas , linux-kernel@vger.kernel.org, Alexei Starovoitov , netdev@vger.kernel.org, Arnd Bergmann , Jessica Yu , Rick Edgecombe , "David S. Miller" , linux-arm-kernel@lists.infradead.org, Kees Cook Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Nov 23, 2018 at 11:18:04PM +0100, Ard Biesheuvel wrote: > The arm64 module region is a 128 MB region that is kept close to > the core kernel, in order to ensure that relative branches are > always in range. So using the same region for programs that do > not have this restriction is wasteful, and preferably avoided. > > Now that the core BPF JIT code permits the alloc/free routines to > be overridden, implement them by vmalloc()/vfree() calls from a > dedicated 128 MB region set aside for BPF programs. This ensures > that BPF programs are still in branching range of each other, which > is something the JIT currently depends upon (and is not guaranteed > when using module_alloc() on KASLR kernels like we do currently). > It also ensures that placement of BPF programs does not correlate > with the placement of the core kernel or modules, making it less > likely that leaking the former will reveal the latter. > > This also solves an issue under KASAN, where shadow memory is > needlessly allocated for all BPF programs (which don't require KASAN > shadow pages since they are not KASAN instrumented) > > Signed-off-by: Ard Biesheuvel > --- > arch/arm64/include/asm/memory.h | 5 ++++- > arch/arm64/net/bpf_jit_comp.c | 13 +++++++++++++ > 2 files changed, 17 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h > index b96442960aea..ee20fc63899c 100644 > --- a/arch/arm64/include/asm/memory.h > +++ b/arch/arm64/include/asm/memory.h > @@ -62,8 +62,11 @@ > #define PAGE_OFFSET (UL(0xffffffffffffffff) - \ > (UL(1) << (VA_BITS - 1)) + 1) > #define KIMAGE_VADDR (MODULES_END) > +#define BPF_JIT_REGION_START (VA_START + KASAN_SHADOW_SIZE) > +#define BPF_JIT_REGION_SIZE (SZ_128M) > +#define BPF_JIT_REGION_END (BPF_JIT_REGION_START + BPF_JIT_REGION_SIZE) > #define MODULES_END (MODULES_VADDR + MODULES_VSIZE) > -#define MODULES_VADDR (VA_START + KASAN_SHADOW_SIZE) > +#define MODULES_VADDR (BPF_JIT_REGION_END) > #define MODULES_VSIZE (SZ_128M) > #define VMEMMAP_START (PAGE_OFFSET - VMEMMAP_SIZE) > #define PCI_IO_END (VMEMMAP_START - SZ_2M) > diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c > index a6fdaea07c63..76c2ab40c02d 100644 > --- a/arch/arm64/net/bpf_jit_comp.c > +++ b/arch/arm64/net/bpf_jit_comp.c > @@ -940,3 +940,16 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog) > tmp : orig_prog); > return prog; > } > + > +void *bpf_jit_alloc_exec(unsigned long size) > +{ > + return __vmalloc_node_range(size, PAGE_SIZE, BPF_JIT_REGION_START, > + BPF_JIT_REGION_END, GFP_KERNEL, > + PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE, > + __builtin_return_address(0)); I guess we'll want VM_IMMEDIATE_UNMAP here if Rich gets that merged. In the meantime, I wonder if it's worth zeroing the region in bpf_jit_free_exec()? (although we'd need the size information...). Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel