From patchwork Wed Apr 3 23:34:48 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Deepak Gupta X-Patchwork-Id: 13616782 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 8F7D8CD129C for ; Wed, 3 Apr 2024 23:41:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:Message-ID:Date:Subject:Cc :To:From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References: List-Owner; bh=QnTTaUxuNTLE4IQcEOtHeoZq8Xx5VobOXSCUlLgc6YY=; b=mQyIgBn+09My7N Q0UICty6vdApcqWQK+4sHvQYYi+J7Sx9wTzx645nXr67m6hIr5ZOiIvQnanHurfCA/x2pLY7pB4Lv zDNbcF9QMfuWi/PCYw6SCpRWPZEQrbzAC57VbsvGkkywgVn2l6KjIJhaRjwZ6fisRqgiRkN1wHcmU ULsShuTdMy7quHpARQTUz5fJ4f05Fx1lM+KWLDhvxtMG91Hvo5m7iq59DXlpA3xtfpo1OGUyOjca4 wqZIj358irQkEBORUV5/gcuDyIXFXmiwmZJVM+tKt1gXCxj4YF8IFr5Q3iPGI266zbbsdRHe1QyxE 3FGjtavpdGjiUxkZ5llg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1rsAEc-00000000ZJf-2icj; Wed, 03 Apr 2024 23:41:38 +0000 Received: from mail-pl1-x629.google.com ([2607:f8b0:4864:20::629]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1rsAEY-00000000ZFl-0HM0 for linux-riscv@lists.infradead.org; Wed, 03 Apr 2024 23:41:35 +0000 Received: by mail-pl1-x629.google.com with SMTP id d9443c01a7336-1e28efd8335so2948885ad.0 for ; Wed, 03 Apr 2024 16:41:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=rivosinc-com.20230601.gappssmtp.com; s=20230601; t=1712187691; x=1712792491; darn=lists.infradead.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=Rv0B5ns63COKymo1kiAr4r2DGtjIZSKU8HdFj+0IH40=; b=eEy1O436ra9LVze519q/wYsD1sDyUW2Q4mt4XpyRxHpS3IyT1oYRoHWaW5byTWs1sN 85Y7tYq1mNvaY/wkG2Mr2fpzgmSyZLlY9bME+LvYZ5lFWXiibFt72NZMvTCTd0mjwRR7 Q0H0RBapH3S3eM+D5mV16cEpKClqBNWk5JBeIfm5oxJ7HRBaPHYytiafYt9Rzq7GGLyu f4UtKcfcC6+14OW1JSlDcC6N6JkjeIJLtd1bBwTXRvCkM6JdaDUXcIKjh8geD1oKKi9a ULQ+ghzPO15k6a6tCKvzQ7hGHiRlzIm0/tGTfuLFVfxWCyf1cReUxPCuNXPgWrSXBl5N 8JgQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1712187691; x=1712792491; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=Rv0B5ns63COKymo1kiAr4r2DGtjIZSKU8HdFj+0IH40=; b=eZpbZG4WQV50tQXRjn4okp9X5awnCCXWnITPkg8/CTrTiCzmatesxWCWbElmsyuq9a srEwZxqN+nXGgupbn/J1ojOpTpz7IfQ8w/7WnIXz5XggRw6V8D/H6q4SD97w2tndhkiL BYx+d18KMYebQ5cE9vqy2er+bJv9GaFGeVZxYp7wCBWAEewpN8WXAy6ET5cr9A5IJ6Lk 6wgq4fEd+tQOdehXTYWGrfZMPeu+P8vqOwlVkSWHBBJt7I92A51avdg54JxMYHwD7n/w GOWo+XeTbWBZES1GFwiGH+5uhfdI3oDT1/y/h6yZKr9CZSda3Wpc4id1gZpuROBXeNmX BCtQ== X-Forwarded-Encrypted: i=1; AJvYcCUlfSnufQyUgRR1NCkDpR/5pcUGSJ0nBmWjnVEHk2OgNq73tHWNcspXquBMVJswNR65ST3IPe8VNq2EFtygkP5xn3NBY0i+PGwrxXFwWRmP X-Gm-Message-State: AOJu0Yx2jqDT1ubjknYa78XeHgpdNQRyK9jgplq6ngx8yMdoI5eRtSMR EXSWfvisthfBg9s0Z0PB90dzUgyolBCZ8N9H1x8gQz0hakpN+nrEr9qu9x6vrFA= X-Google-Smtp-Source: AGHT+IG0BMforFKG/Z+mj8l+gwmdkHRGf0wkX6Dm3/AG2fDf6ErYVT/6uGhIGHy46uRoq1WTT9/6ig== X-Received: by 2002:a17:902:c402:b0:1dd:c953:cfa0 with SMTP id k2-20020a170902c40200b001ddc953cfa0mr1051389plk.48.1712187690540; Wed, 03 Apr 2024 16:41:30 -0700 (PDT) Received: from debug.ba.rivosinc.com ([64.71.180.162]) by smtp.gmail.com with ESMTPSA id b18-20020a170902d51200b001deeac592absm13899117plg.180.2024.04.03.16.41.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 03 Apr 2024 16:41:30 -0700 (PDT) From: Deepak Gupta To: paul.walmsley@sifive.com, rick.p.edgecombe@intel.com, broonie@kernel.org, Szabolcs.Nagy@arm.com, kito.cheng@sifive.com, keescook@chromium.org, ajones@ventanamicro.com, conor.dooley@microchip.com, cleger@rivosinc.com, atishp@atishpatra.org, alex@ghiti.fr, bjorn@rivosinc.com, alexghiti@rivosinc.com, samuel.holland@sifive.com, conor@kernel.org Cc: linux-doc@vger.kernel.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-kselftest@vger.kernel.org, corbet@lwn.net, palmer@dabbelt.com, aou@eecs.berkeley.edu, robh+dt@kernel.org, krzysztof.kozlowski+dt@linaro.org, oleg@redhat.com, akpm@linux-foundation.org, arnd@arndb.de, ebiederm@xmission.com, Liam.Howlett@oracle.com, vbabka@suse.cz, lstoakes@gmail.com, shuah@kernel.org, brauner@kernel.org, debug@rivosinc.com, andy.chiu@sifive.com, jerry.shih@sifive.com, hankuan.chen@sifive.com, greentime.hu@sifive.com, evan@rivosinc.com, xiao.w.wang@intel.com, charlie@rivosinc.com, apatel@ventanamicro.com, mchitale@ventanamicro.com, dbarboza@ventanamicro.com, sameo@rivosinc.com, shikemeng@huaweicloud.com, willy@infradead.org, vincent.chen@sifive.com, guoren@kernel.org, samitolvanen@google.com, songshuaishuai@tinylab.org, gerg@kernel.org, heiko@sntech.de, bhe@redhat.com, jeeheng.sia@starfivetech.com, cyy@cyyself.name, maskray@google.com, ancientmodern4@gmail.com, mathis.salmen@matsal.de, cuiyunhui@bytedance.com, bgray@linux.ibm.com, mpe@ellerman.id.au, baruch@tkos.co.il, alx@kernel.org, david@redhat.com, catalin.marinas@arm.com, revest@chromium.org, josh@joshtriplett.org, shr@devkernel.io, deller@gmx.de, omosnace@redhat.com, ojeda@kernel.org, jhubbard@nvidia.com Subject: [PATCH v3 00/29] riscv control-flow integrity for usermode Date: Wed, 3 Apr 2024 16:34:48 -0700 Message-ID: <20240403234054.2020347-1-debug@rivosinc.com> X-Mailer: git-send-email 2.43.2 MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240403_164134_252975_D5791DBC X-CRM114-Status: GOOD ( 13.71 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org Sending out v3 for cpu assisted riscv user mode control flow integrity. v2 [9] was sent a week ago for this riscv usermode control flow integrity enabling. RFC patchset was (v1) early this year (January) [7]. changes in v3 -------------- envcfg: logic to pick up base envcfg had a bug where `ENVCFG_CBZE` could have been picked on per task basis, even though CPU didn't implement it. Fixed in this series. dt-bindings: As suggested, split into separate commit. fixed the messaging that spec is in public review arch_is_shadow_stack change: arch_is_shadow_stack changed to vma_is_shadow_stack hwprobe: zicfiss / zicfilp if present will get enumerated in hwprobe selftests: As suggested, added object and binary filenames to .gitignore Selftest binary anyways need to be compiled with cfi enabled compiler which will make sure that landing pad and shadow stack are enabled. Thus removed separate enable/disable tests. Cleaned up tests a bit. changes in v2 --------------- As part of testing effort, compiled a rootfs with shadow stack and landing pad enabled (libraries and binaries) and booted to shell. As part of long running tests, I have been able to run some spec 2006 benchmarks [8] (here link is provided only for list of benchmarks that were tested for long running tests, excel sheet provided here actually is for some static stats like code size growth on spec binaries). Thus converting from RFC to regular patchset. Securing control-flow integrity for usermode requires following - Securing forward control flow : All callsites must reach reach a target that they actually intend to reach. - Securing backward control flow : All function returns must return to location where they were called from. This patch series use riscv cpu extension `zicfilp` [2] to secure forward control flow and `zicfiss` [2] to secure backward control flow. `zicfilp` enforces that all indirect calls or jmps must land on a landing pad instr and label embedded in landing pad instr must match a value programmed in `x7` register (at callsite via compiler). `zicfiss` introduces shadow stack which can only be writeable via shadow stack instructions (sspush and ssamoswap) and thus can't be tampered with via inadvertent stores. More details about extension can be read from [2] and there are details in documentation as well (in this patch series). Using config `CONFIG_RISCV_USER_CFI`, kernel support for riscv control flow integrity for user mode programs can be compiled in the kernel. Enabling of control flow integrity for user programs is left to user runtime (specifically expected from dynamic loader). There has been a lot of earlier discussion on the enabling topic around x86 shadow stack enabling [3, 4, 5] and overall consensus had been to let dynamic loader (or usermode) to decide for enabling the feature. This patch series introduces arch agnostic `prctls` to enable shadow stack and indirect branch tracking. And implements them on riscv. arm64 is expected to implement shadow stack part of these arch agnostic `prctls` [6] Changes since last time *********************** Spec changes ------------ - Forward cfi spec has become much simpler. `lpad` instruction is pseudo for `auipc rd, <20bit_imm>`. `lpad` checks x7 against 20bit embedded in instr. Thus label width is 20bit. - Shadow stack management instructions are reduced to sspush - to push x1/x5 on shadow stack sspopchk - pops from shadow stack and comapres with x1/x5. ssamoswap - atomically swap value on shadow stack. rdssp - reads current shadow stack pointer - Shadow stack accesses on readonly memory always raise AMO/store page fault. `sspopchk` is load but if underlying page is readonly, it'll raise a store page fault. It simplifies hardware and kernel for COW handling for shadow stack pages. - riscv defines a new exception type `software check exception` and control flow violations raise software check exception. - enabling controls for shadow stack and landing are in xenvcfg CSR and controls lower privilege mode enabling. As an example senvcfg controls enabling for U and menvcfg controls enabling for S mode. core mm shadow stack enabling ----------------------------- Shadow stack for x86 usermode are now in mainline and thus this patch series builds on top of that for arch-agnostic mm related changes. Big thanks and shout out to Rick Edgecombe for that. selftests --------- Created some minimal selftests to test the patch series. [1] - https://lore.kernel.org/lkml/20230213045351.3945824-1-debug@rivosinc.com/ [2] - https://github.com/riscv/riscv-cfi [3] - https://lore.kernel.org/lkml/ZWHcBq0bJ+15eeKs@finisterre.sirena.org.uk/T/#mb121cd8b33d564e64234595a0ec52211479cf474 [4] - https://lore.kernel.org/all/20220130211838.8382-1-rick.p.edgecombe@intel.com/ [5] - https://lore.kernel.org/lkml/CAHk-=wgP5mk3poVeejw16Asbid0ghDt4okHnWaWKLBkRhQntRA@mail.gmail.com/ [6] - https://lore.kernel.org/linux-mm/20231122-arm64-gcs-v7-2-201c483bd775@kernel.org/ [7] - https://lore.kernel.org/lkml/20240125062739.1339782-1-debug@rivosinc.com/ [8] - https://docs.google.com/spreadsheets/d/1_cHGH4ctNVvFRiS7hW9dEGKtXLAJ3aX4Z_iTSa3Tw2U/edit#gid=0 [9] - https://lore.kernel.org/lkml/20240329044459.3990638-1-debug@rivosinc.com/