From patchwork Wed Feb 5 01:21:53 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Deepak Gupta X-Patchwork-Id: 13960340 Received: from mail-pl1-f171.google.com (mail-pl1-f171.google.com [209.85.214.171]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 67DBC22A4DC for ; Wed, 5 Feb 2025 01:22:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.171 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738718529; cv=none; b=ScySVwkmxWR9BVKOebCV4h/6u21h0Cg7WR+n3i+bkkQgfE7yWkh2s9zC2Yg8u9pfdp+BEZgDFq9OVoHa+g2d5Jbdsv+WMQF7mpMmLncegSRF3lbnPBujhZG8u9DWG3MuX1v6NzR+jPiQ+Aq1h9ofu86pynjimkJdtFbAG1Azea0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738718529; c=relaxed/simple; bh=toOY3g5UWbhyzFvpokgMbtCDrGwGLK+0MjdImo2Zc6U=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=Elk8GtVqhUMPEhv9wgAtTRQ1Kg9CXrPkZbPzA/FhfhsA4uQmTr+p5Odx6ctSQ+mzR4tWvOKuq5LAMq6n1tYuRy1rp2a/mlEn37eBU4VsaxFSneAAXrfnrvrIlhlhRDvG6rgPlCn/1YktxtBHlYWz8c7Ukrj9SiLKRHgJZxjKj1A= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=rivosinc.com; spf=pass smtp.mailfrom=rivosinc.com; dkim=pass (2048-bit key) header.d=rivosinc-com.20230601.gappssmtp.com header.i=@rivosinc-com.20230601.gappssmtp.com header.b=dtzwY2m+; arc=none smtp.client-ip=209.85.214.171 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=rivosinc.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=rivosinc.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=rivosinc-com.20230601.gappssmtp.com header.i=@rivosinc-com.20230601.gappssmtp.com header.b="dtzwY2m+" Received: by mail-pl1-f171.google.com with SMTP id d9443c01a7336-2161eb95317so110997395ad.1 for ; Tue, 04 Feb 2025 17:22:06 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=rivosinc-com.20230601.gappssmtp.com; s=20230601; t=1738718525; x=1739323325; darn=vger.kernel.org; h=cc:to:in-reply-to:references:message-id:content-transfer-encoding :mime-version:subject:date:from:from:to:cc:subject:date:message-id :reply-to; bh=1e5RgGuqZS+AKw5oTSgp47pWFJ0GDjWFc7jT6Xd5TJc=; b=dtzwY2m+FXezOKTSyjlDXgShTfRgwP5V1LTUmMIN22MWLRnKo+naWRMD/JvGnNSHaS UUbpg9X5n8TvdK3S2HsoBDqGpz2mlBktoSn+gyQqgdSrHiDc8RqR5hMWTmcfD2fJsG2x zPgR2oOKyXDsGyuLr3eyF2tEyHP06A1swN5pB0LMzNGwAjSCWxtikh7jIZEOgoFPZTyi xCIugqe79snPlKcgI9jwb8ubPbhhD6wmZ5r3wCLybUyw/JoZL/E92BpqrXzKo5SOUSBv g1EheIWV7IxZqZEquxGRTg3DYkkTEdBBvrH64yF6x6/5MvX9CG1IEWzsRCgSGygg5s/T eXtQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1738718525; x=1739323325; h=cc:to:in-reply-to:references:message-id:content-transfer-encoding :mime-version:subject:date:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=1e5RgGuqZS+AKw5oTSgp47pWFJ0GDjWFc7jT6Xd5TJc=; b=vF+cVQX3nv3nS8Xk//aQQn/5U/1MtH8/5UWm0Va8qF5mLCKhvs/kCH/KIfXvAzwS9R B7pMuL9jIbvdla3JaF2BsMTYIZ+Ij81vcPk+3xSVLsLxQLyMpKEGtDaOU14MAVWqjTNI vpbRm4c1yfIHxNTNzrTgL5LTTXdyp0poinJMvDwMiCn6p5q4YB2qrr4oTMftjlBOsRiY qsUhJPCC11qj4eLmaSaH6R3gDMrYL2AJ0mtpOZCyFYWegcM6yzaKfx+f6JenMBxQrHJn H/1o/XtkHm4JCa7Tza0LFZ8Ts0fBAILVLJgzekwydYoF9pfU4/Ie1+dj/IjrwtCpBbPP ZeGg== X-Forwarded-Encrypted: i=1; AJvYcCXeku+Ki/mGEJwN6Lf9BkN6QUVBDKl79NuW/LGXviaC2OYv1jxBC0HmlfeDmkdEK4/z+5/Z0NI7enDbh3NK@vger.kernel.org X-Gm-Message-State: AOJu0Yy6GZpmPbFwcBDHx30STXRi2mmgYjuJv3BMlFp3YKr7wsdDZYiq RsKiMC5aRzE7I/XCEa2u0WRwaXOChYbnjlOiikI1u083HdJAvtQL1F8IMHaRZaA= X-Gm-Gg: ASbGncssKtV27/Kd6ix9mjHMvPen8ca46IA2Ninh/DZTZoO5Ww0BCOmNAR3E175yYSw o1guLl5mAFiiybECDpbJrvYGIHqtgtaZNQgitHCuUTFoOfjxGdornt+8W6i/6hjojaCSgLPanDR IIu3KswA4DI0ApKO//ksamQMoxn4jKjJ/f4P6QeXWIdfG1ggQDRqs5BrQgjf3ZcapY0PjpoHW6e 8F6WqFiaNsLsO2K6pfiFdUkVk2ldcdrj0NxFH1LpfFJWU/FbdT9oPJPzVYqMJt1FjkQIOmzbZaA OpZAzZKaxZR+2V6Es1UYvH3hGg== X-Google-Smtp-Source: AGHT+IGmwZmqjzvPRO4j1QnW6c26qtiThBAMPujeU03hhi/wAPDw8k7cHzAb2QmKpofb/oE3lFc7aw== X-Received: by 2002:a05:6a00:e13:b0:725:e37d:cd36 with SMTP id d2e1a72fcca58-730350e4f2amr1787173b3a.2.1738718525565; Tue, 04 Feb 2025 17:22:05 -0800 (PST) Received: from debug.ba.rivosinc.com ([64.71.180.162]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-72fe69cec0fsm11457202b3a.137.2025.02.04.17.22.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 04 Feb 2025 17:22:05 -0800 (PST) From: Deepak Gupta Date: Tue, 04 Feb 2025 17:21:53 -0800 Subject: [PATCH v9 06/26] riscv/mm : ensure PROT_WRITE leads to VM_READ | VM_WRITE Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20250204-v5_user_cfi_series-v9-6-b37a49c5205c@rivosinc.com> References: <20250204-v5_user_cfi_series-v9-0-b37a49c5205c@rivosinc.com> In-Reply-To: <20250204-v5_user_cfi_series-v9-0-b37a49c5205c@rivosinc.com> To: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Andrew Morton , "Liam R. Howlett" , Vlastimil Babka , Lorenzo Stoakes , Paul Walmsley , Palmer Dabbelt , Albert Ou , Conor Dooley , Rob Herring , Krzysztof Kozlowski , Arnd Bergmann , Christian Brauner , Peter Zijlstra , Oleg Nesterov , Eric Biederman , Kees Cook , Jonathan Corbet , Shuah Khan , Jann Horn , Conor Dooley Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-riscv@lists.infradead.org, devicetree@vger.kernel.org, linux-arch@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, alistair.francis@wdc.com, richard.henderson@linaro.org, jim.shu@sifive.com, andybnac@gmail.com, kito.cheng@sifive.com, charlie@rivosinc.com, atishp@rivosinc.com, evan@rivosinc.com, cleger@rivosinc.com, alexghiti@rivosinc.com, samitolvanen@google.com, broonie@kernel.org, rick.p.edgecombe@intel.com, Deepak Gupta X-Mailer: b4 0.14.0 `arch_calc_vm_prot_bits` is implemented on risc-v to return VM_READ | VM_WRITE if PROT_WRITE is specified. Similarly `riscv_sys_mmap` is updated to convert all incoming PROT_WRITE to (PROT_WRITE | PROT_READ). This is to make sure that any existing apps using PROT_WRITE still work. Earlier `protection_map[VM_WRITE]` used to pick read-write PTE encodings. Now `protection_map[VM_WRITE]` will always pick PAGE_SHADOWSTACK PTE encodings for shadow stack. Above changes ensure that existing apps continue to work because underneath kernel will be picking `protection_map[VM_WRITE|VM_READ]` PTE encodings. Signed-off-by: Deepak Gupta --- arch/riscv/include/asm/mman.h | 25 +++++++++++++++++++++++++ arch/riscv/include/asm/pgtable.h | 1 + arch/riscv/kernel/sys_riscv.c | 10 ++++++++++ arch/riscv/mm/init.c | 2 +- 4 files changed, 37 insertions(+), 1 deletion(-) diff --git a/arch/riscv/include/asm/mman.h b/arch/riscv/include/asm/mman.h new file mode 100644 index 000000000000..392c9c2d2e78 --- /dev/null +++ b/arch/riscv/include/asm/mman.h @@ -0,0 +1,25 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __ASM_MMAN_H__ +#define __ASM_MMAN_H__ + +#include +#include +#include + +static inline unsigned long arch_calc_vm_prot_bits(unsigned long prot, + unsigned long pkey __always_unused) +{ + unsigned long ret = 0; + + /* + * If PROT_WRITE was specified, force it to VM_READ | VM_WRITE. + * Only VM_WRITE means shadow stack. + */ + if (prot & PROT_WRITE) + ret = (VM_READ | VM_WRITE); + return ret; +} + +#define arch_calc_vm_prot_bits(prot, pkey) arch_calc_vm_prot_bits(prot, pkey) + +#endif /* ! __ASM_MMAN_H__ */ diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h index 050fdc49b5ad..8c528cd7347a 100644 --- a/arch/riscv/include/asm/pgtable.h +++ b/arch/riscv/include/asm/pgtable.h @@ -178,6 +178,7 @@ extern struct pt_alloc_ops pt_ops __meminitdata; #define PAGE_READ_EXEC __pgprot(_PAGE_BASE | _PAGE_READ | _PAGE_EXEC) #define PAGE_WRITE_EXEC __pgprot(_PAGE_BASE | _PAGE_READ | \ _PAGE_EXEC | _PAGE_WRITE) +#define PAGE_SHADOWSTACK __pgprot(_PAGE_BASE | _PAGE_WRITE) #define PAGE_COPY PAGE_READ #define PAGE_COPY_EXEC PAGE_READ_EXEC diff --git a/arch/riscv/kernel/sys_riscv.c b/arch/riscv/kernel/sys_riscv.c index d77afe05578f..43a448bf254b 100644 --- a/arch/riscv/kernel/sys_riscv.c +++ b/arch/riscv/kernel/sys_riscv.c @@ -7,6 +7,7 @@ #include #include +#include static long riscv_sys_mmap(unsigned long addr, unsigned long len, unsigned long prot, unsigned long flags, @@ -16,6 +17,15 @@ static long riscv_sys_mmap(unsigned long addr, unsigned long len, if (unlikely(offset & (~PAGE_MASK >> page_shift_offset))) return -EINVAL; + /* + * If PROT_WRITE is specified then extend that to PROT_READ + * protection_map[VM_WRITE] is now going to select shadow stack encodings. + * So specifying PROT_WRITE actually should select protection_map [VM_WRITE | VM_READ] + * If user wants to create shadow stack then they should use `map_shadow_stack` syscall. + */ + if (unlikely((prot & PROT_WRITE) && !(prot & PROT_READ))) + prot |= PROT_READ; + return ksys_mmap_pgoff(addr, len, prot, flags, fd, offset >> (PAGE_SHIFT - page_shift_offset)); } diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c index 15b2eda4c364..9d6661638d0b 100644 --- a/arch/riscv/mm/init.c +++ b/arch/riscv/mm/init.c @@ -342,7 +342,7 @@ pgd_t early_pg_dir[PTRS_PER_PGD] __initdata __aligned(PAGE_SIZE); static const pgprot_t protection_map[16] = { [VM_NONE] = PAGE_NONE, [VM_READ] = PAGE_READ, - [VM_WRITE] = PAGE_COPY, + [VM_WRITE] = PAGE_SHADOWSTACK, [VM_WRITE | VM_READ] = PAGE_COPY, [VM_EXEC] = PAGE_EXEC, [VM_EXEC | VM_READ] = PAGE_READ_EXEC,