From nobody Sat Nov 30 04:28:02 2024 Received: from mail-pg1-f178.google.com (mail-pg1-f178.google.com [209.85.215.178]) (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 2AEDE1CE6F6 for ; Thu, 12 Sep 2024 23:18:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.178 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726183102; cv=none; b=f0BYmk7TDvqMULw34Zb7odu9PBZ7qhaCNJTfaWNh4a/8dSRo4vKENpXLfzJL18jat/x1AI4KSSeCDBOVFOWIu6t22/+d8eDVsPjRO2heiRGcnAHdvJpqE+S6LR0XxvcQPg+tNJkeyCmYCBTeJZxotiAVzy1F1LzXq0fumOY/UAA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726183102; c=relaxed/simple; bh=FexWTcT/JM8SK800zKhbpjalwrQiIdPN/R2m+9TJjqI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=b1EhQjuTyU3c1D39vvRFb6DF299BRRGyuYNIf0fzEzcUUprwswqaaod2imh8YTdaFEJkWVBD72S0NqlBNqOT1Hq07yzHwDhqWv9n6ZcoFVmiHaRs6vI40SyJBtHF7QpBORhLAt9n6ny4E1up+GHwyTmsmayrY0y3Nt3CQdbEVjI= 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=q6yXfE9h; arc=none smtp.client-ip=209.85.215.178 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="q6yXfE9h" Received: by mail-pg1-f178.google.com with SMTP id 41be03b00d2f7-7cf5e179b68so1281088a12.1 for ; Thu, 12 Sep 2024 16:18:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=rivosinc-com.20230601.gappssmtp.com; s=20230601; t=1726183100; x=1726787900; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=eQcGpVU0IdnPD1mHTUz69E9YXFdr868sAk68PrVb1pE=; b=q6yXfE9hPEn5jUvDyYW+G/HsTy1tn2BPsuTQOm4R3EmQ2WvobJdDJtejNOuQ3k2WPY RhCuRgghxMSfXLb+aprOTg9TolTIw+Igik0clyk9rUzp4WZmB+YynEgn5dasNIA8RIIw UNPPy5w129KKqAVZCfQz36ftQKi5JRf88OfosDQKuEE7cqkeaoCKkIyhUkNg6Xkr2F+o b+m7zCNc7nDa+nYjsHurfW0WxlzioMHbJHABzQKsOCsvqv2Muhn/c1z726muahNt2WQC fMj7EK2KQO+GWpyqALygHbq7++rW/5+GsV3te/Wqmc0s28nkY74zRnazCt55A4Bjx+tt cfQw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1726183100; x=1726787900; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=eQcGpVU0IdnPD1mHTUz69E9YXFdr868sAk68PrVb1pE=; b=Mr9bptBfn/mg7IV3AnUvlzlYAvZ+29p5YSH1wIF25g9EFT7NCODLAwSQI6lJ2eocG9 be2m09B9c6b4hBqagT2Q35TKNXw5Mcif4yT8Jl/OFazFka8LHKNbWtLcrCI0w4Gea/hp 8b4uh3eVtpz8UnBvIH61Ms+pe9rqlnLvyr2iL5vkmisCSo+3tnpgMhzSrf/E28+ui0r1 /YCvcoG27eFn7+pKFOopNI5x5KWKEYRN3QIDk+opzM9079bhyPJCA4+oe1+3WE+aIn4+ smE6gyCTbp7i6pBpNwpeeLZlzU14wVTbKZ3T7XkCM8F8HJluJ7ZAIrygHqyB7MDNRiSP qQ1g== X-Forwarded-Encrypted: i=1; AJvYcCUWS+5348hEOvJBfoTCF775U/Q9RRGY45z27O/nu+pJl4b2xOD4r+S14WwAXErrYgjEtxZg/LDGYRfNKqg=@vger.kernel.org X-Gm-Message-State: AOJu0YwFV9/53Nt5+kFWqEnaVRf37C04GLF1RxvOOe+P+PWWonh5QqjJ R6JBQyxhvmlHFkvYXtb7VqkRy4CXIPoUqI2N/ZhhABGeqe+KIhOQXS4hyxcG1zU= X-Google-Smtp-Source: AGHT+IFff016Dc/UvJnFaAb1uH5IeOSLPpio1EAHCPI04vBCz6X3EEqRQxY7cO8q2vilVk8FL6IgYg== X-Received: by 2002:a17:90a:2c0f:b0:2d8:25ce:e6e3 with SMTP id 98e67ed59e1d1-2db6718d8b4mr19220198a91.5.1726183100307; Thu, 12 Sep 2024 16:18:20 -0700 (PDT) Received: from debug.ba.rivosinc.com ([64.71.180.162]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-2db6c1ac69asm3157591a91.0.2024.09.12.16.18.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 12 Sep 2024 16:18:19 -0700 (PDT) From: Deepak Gupta To: paul.walmsley@sifive.com, palmer@sifive.com, conor@kernel.org, linux-doc@vger.kernel.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-kselftest@vger.kernel.org Cc: corbet@lwn.net, palmer@dabbelt.com, aou@eecs.berkeley.edu, robh@kernel.org, krzk+dt@kernel.org, oleg@redhat.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, peterz@infradead.org, akpm@linux-foundation.org, arnd@arndb.de, ebiederm@xmission.com, kees@kernel.org, Liam.Howlett@oracle.com, vbabka@suse.cz, lorenzo.stoakes@oracle.com, shuah@kernel.org, brauner@kernel.org, samuel.holland@sifive.com, debug@rivosinc.com, andy.chiu@sifive.com, jerry.shih@sifive.com, greentime.hu@sifive.com, charlie@rivosinc.com, evan@rivosinc.com, cleger@rivosinc.com, xiao.w.wang@intel.com, ajones@ventanamicro.com, anup@brainfault.org, mchitale@ventanamicro.com, atishp@rivosinc.com, sameo@rivosinc.com, bjorn@rivosinc.com, alexghiti@rivosinc.com, david@redhat.com, libang.li@antgroup.com, jszhang@kernel.org, leobras@redhat.com, guoren@kernel.org, samitolvanen@google.com, songshuaishuai@tinylab.org, costa.shul@redhat.com, bhe@redhat.com, zong.li@sifive.com, puranjay@kernel.org, namcaov@gmail.com, antonb@tenstorrent.com, sorear@fastmail.com, quic_bjorande@quicinc.com, ancientmodern4@gmail.com, ben.dooks@codethink.co.uk, quic_zhonhan@quicinc.com, cuiyunhui@bytedance.com, yang.lee@linux.alibaba.com, ke.zhao@shingroup.cn, sunilvl@ventanamicro.com, tanzhasanwork@gmail.com, schwab@suse.de, dawei.li@shingroup.cn, rppt@kernel.org, willy@infradead.org, usama.anjum@collabora.com, osalvador@suse.de, ryan.roberts@arm.com, andrii@kernel.org, alx@kernel.org, catalin.marinas@arm.com, broonie@kernel.org, revest@chromium.org, bgray@linux.ibm.com, deller@gmx.de, zev@bewilderbeest.net Subject: [PATCH v4 17/30] prctl: arch-agnostic prctl for shadow stack Date: Thu, 12 Sep 2024 16:16:36 -0700 Message-ID: <20240912231650.3740732-18-debug@rivosinc.com> X-Mailer: git-send-email 2.45.0 In-Reply-To: <20240912231650.3740732-1-debug@rivosinc.com> References: <20240912231650.3740732-1-debug@rivosinc.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Mark Brown Three architectures (x86, aarch64, riscv) have announced support for shadow stacks with fairly similar functionality. While x86 is using arch_prctl() to control the functionality neither arm64 nor riscv uses that interface so this patch adds arch-agnostic prctl() support to get and set status of shadow stacks and lock the current configuration to prevent further changes, with support for turning on and off individual subfeatures so applications can limit their exposure to features that they do not need. The features are: - PR_SHADOW_STACK_ENABLE: Tracking and enforcement of shadow stacks, including allocation of a shadow stack if one is not already allocated. - PR_SHADOW_STACK_WRITE: Writes to specific addresses in the shadow stack. - PR_SHADOW_STACK_PUSH: Push additional values onto the shadow stack. - PR_SHADOW_STACK_DISABLE: Allow to disable shadow stack. Note once locked, disable must fail. These features are expected to be inherited by new threads and cleared on exec(), unknown features should be rejected for enable but accepted for locking (in order to allow for future proofing). This is based on a patch originally written by Deepak Gupta but later modified by Mark Brown for arm's GCS patch series. Signed-off-by: Mark Brown Co-developed-by: Deepak Gupta Signed-off-by: Deepak Gupta --- include/linux/mm.h | 3 +++ include/uapi/linux/prctl.h | 21 +++++++++++++++++++++ kernel/sys.c | 30 ++++++++++++++++++++++++++++++ 3 files changed, 54 insertions(+) diff --git a/include/linux/mm.h b/include/linux/mm.h index f0dc94fb782a..e3acb4297877 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -4215,6 +4215,9 @@ static inline bool pfn_is_unaccepted_memory(unsigned = long pfn) =20 return range_contains_unaccepted_memory(paddr, paddr + PAGE_SIZE); } +int arch_get_shadow_stack_status(struct task_struct *t, unsigned long __us= er *status); +int arch_set_shadow_stack_status(struct task_struct *t, unsigned long stat= us); +int arch_lock_shadow_stack_status(struct task_struct *t, unsigned long sta= tus); =20 void vma_pgtable_walk_begin(struct vm_area_struct *vma); void vma_pgtable_walk_end(struct vm_area_struct *vma); diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h index 35791791a879..b8d7b6361754 100644 --- a/include/uapi/linux/prctl.h +++ b/include/uapi/linux/prctl.h @@ -327,5 +327,26 @@ struct prctl_mm_map { # define PR_PPC_DEXCR_CTRL_SET_ONEXEC 0x8 /* Set the aspect on exec */ # define PR_PPC_DEXCR_CTRL_CLEAR_ONEXEC 0x10 /* Clear the aspect on exec */ # define PR_PPC_DEXCR_CTRL_MASK 0x1f +/* + * Get the current shadow stack configuration for the current thread, + * this will be the value configured via PR_SET_SHADOW_STACK_STATUS. + */ +#define PR_GET_SHADOW_STACK_STATUS 74 + +/* + * Set the current shadow stack configuration. Enabling the shadow + * stack will cause a shadow stack to be allocated for the thread. + */ +#define PR_SET_SHADOW_STACK_STATUS 75 +# define PR_SHADOW_STACK_ENABLE (1UL << 0) +# define PR_SHADOW_STACK_WRITE (1UL << 1) +# define PR_SHADOW_STACK_PUSH (1UL << 2) + +/* + * Prevent further changes to the specified shadow stack + * configuration. All bits may be locked via this call, including + * undefined bits. + */ +#define PR_LOCK_SHADOW_STACK_STATUS 76 =20 #endif /* _LINUX_PRCTL_H */ diff --git a/kernel/sys.c b/kernel/sys.c index 3a2df1bd9f64..7e0c10e867cf 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -2324,6 +2324,21 @@ int __weak arch_prctl_spec_ctrl_set(struct task_stru= ct *t, unsigned long which, return -EINVAL; } =20 +int __weak arch_get_shadow_stack_status(struct task_struct *t, unsigned lo= ng __user *status) +{ + return -EINVAL; +} + +int __weak arch_set_shadow_stack_status(struct task_struct *t, unsigned lo= ng status) +{ + return -EINVAL; +} + +int __weak arch_lock_shadow_stack_status(struct task_struct *t, unsigned l= ong status) +{ + return -EINVAL; +} + #define PR_IO_FLUSHER (PF_MEMALLOC_NOIO | PF_LOCAL_THROTTLE) =20 #ifdef CONFIG_ANON_VMA_NAME @@ -2782,6 +2797,21 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, a= rg2, unsigned long, arg3, case PR_RISCV_SET_ICACHE_FLUSH_CTX: error =3D RISCV_SET_ICACHE_FLUSH_CTX(arg2, arg3); break; + case PR_GET_SHADOW_STACK_STATUS: + if (arg3 || arg4 || arg5) + return -EINVAL; + error =3D arch_get_shadow_stack_status(me, (unsigned long __user *) arg2= ); + break; + case PR_SET_SHADOW_STACK_STATUS: + if (arg3 || arg4 || arg5) + return -EINVAL; + error =3D arch_set_shadow_stack_status(me, arg2); + break; + case PR_LOCK_SHADOW_STACK_STATUS: + if (arg3 || arg4 || arg5) + return -EINVAL; + error =3D arch_lock_shadow_stack_status(me, arg2); + break; default: error =3D -EINVAL; break; --=20 2.45.0