From patchwork Tue Mar 19 21:58:33 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Samuel Holland X-Patchwork-Id: 13597087 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 B652BCD11DC for ; Tue, 19 Mar 2024 21:59:44 +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:References:In-Reply-To: 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: List-Owner; bh=9v3Bt0Fzls8swId5mt3M+G2tw3nIlSxxhL6YENVRjZ4=; b=fUOKn5CNneYUqO p1gy8WmSAPPVcNywdcs8yTP1D6tpqbq1LtagRaF1gUYZs9xl8bOpZ8ppzD6Wol8TRn4s+zRqR8Sw7 1j/OFkzbM1eMXNdIZ7Fn5AXdL1RAkzmxZE6g8KVddz89Bd+CNxEeY2xoWV/x9XiMpd2oiHRfLXnHf Iv9OLfMJJOyVnFJAZZ/R8ddsNTsHKh5jmnJDtTDzyppgH+tc+iZyDGkDGJxV53H1ctJcsaFbJ60x7 FwJl3sYKdN7C713X9ZJVcA/zNO8hHm6kivkHMcmjlMzCxJcHFqZeIcAdq79+xdTQBST5hT0Btr2E0 LUQxq8yF92CN2LAvGYLw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1rmhUh-0000000EMpQ-3TVB; Tue, 19 Mar 2024 21:59:39 +0000 Received: from mail-pf1-x42f.google.com ([2607:f8b0:4864:20::42f]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1rmhUW-0000000EMh1-3jwE for linux-riscv@lists.infradead.org; Tue, 19 Mar 2024 21:59:31 +0000 Received: by mail-pf1-x42f.google.com with SMTP id d2e1a72fcca58-6e782e955adso75013b3a.3 for ; Tue, 19 Mar 2024 14:59:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sifive.com; s=google; t=1710885567; x=1711490367; darn=lists.infradead.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=//J7AYtv61iHxtKJQn3MiSxiIHpG2s0TTUnDmfuJahA=; b=Q96xe04TSIkUCqTY5Tl684ziyNkoAV/4lkGkFwj/qbQFttHvcODkYu7bg3EajeOQHo 1WO/BkdEmAIxJFGNTjj2hYPzYVSACOC8vFToRoLu5CsdT7h8XK7BZLk1gAu6D+YrUS8l tuFMsqUyp5gwJQvjaw0am5ZBoN+9eAzWqfldyY5DmHQCZ9Ipgqg3EN24UH2cFhAbfzMT vWmKpKNPFGyLeLHJvyLg/Ar/Yql6XdHkkI5QXtXi9PsCB2wUFAG3zvIg75sNYnjVQTiK Ig7EbiLqtfespaIiv4LCx21hCHUOYFv7NRQLFHqeMVDMWKi3raGNd/wofEsfPO7dsIWG FusQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1710885567; x=1711490367; 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=//J7AYtv61iHxtKJQn3MiSxiIHpG2s0TTUnDmfuJahA=; b=EYzhGlCIfpzPuzsxforG9YzVqqMFD88p16Dsx9ntTsMMJvAFFOiNSQwLiQfJvhnkqQ V5Wm8LTlo6FBHhvZmab+W7wzC3HD7404cMX1+M+cwbkEVFiJ4tBt3o3V8HYlWh+YvEAV DPnzZykNxyilMIOret93pW7eCGJkvBhSbjqEIoV6C6Dhk2eCx6e6G3MtNmcQ0OREwKxm zYVaTooE1KgszJ1PyXBNdwy3cEyhEqDFU5rQ0DAYWPHeTppPUZ+cxZIsV8WbM+NsTEa5 1pTtu7fmpSv1pwZQTEVheEXkv5bvUMVw3tYmnE5JfuS3gD5eL+MwIj7fVOvOIGczXPiQ hH4w== X-Forwarded-Encrypted: i=1; AJvYcCVrR0DAh/AB7EjS+nMvZ9wF1dc42JYB3kBY2NuvWhwsHcn4aHytIPPT64Dbtwe9XoTq1p5+ffPxG2Ei5VOejJVS6PWvQeuLlUaGTEHKaZHq X-Gm-Message-State: AOJu0YzKVjO88mmZTmaZ7SX8c1MjpwwT+/h3MPVNpN+LlQdi+JSXhVwU XD+VkSomZIkO8XPx9ergnMwVw9t3g4S/DZbaXRcdLu5MzM7x3JJEk9kUFGCjoY4= X-Google-Smtp-Source: AGHT+IFBtKPHZqAeY1IySQ3pzoH0nMl2mX+/T7GPlQacqCenBzo0xWbZizuV66Z+QSEH8NLBCD7ebQ== X-Received: by 2002:a05:6a00:2447:b0:6e6:aae6:acfe with SMTP id d7-20020a056a00244700b006e6aae6acfemr19345714pfj.23.1710885565732; Tue, 19 Mar 2024 14:59:25 -0700 (PDT) Received: from sw06.internal.sifive.com ([4.53.31.132]) by smtp.gmail.com with ESMTPSA id z25-20020aa785d9000000b006e6c61b264bsm10273892pfn.32.2024.03.19.14.59.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 19 Mar 2024 14:59:25 -0700 (PDT) From: Samuel Holland To: Palmer Dabbelt , linux-riscv@lists.infradead.org Cc: devicetree@vger.kernel.org, Catalin Marinas , linux-kernel@vger.kernel.org, tech-j-ext@lists.risc-v.org, Conor Dooley , kasan-dev@googlegroups.com, Evgenii Stepanov , Krzysztof Kozlowski , Rob Herring , Samuel Holland , Albert Ou , Greentime Hu Subject: [RFC PATCH 7/9] riscv: Add support for the tagged address ABI Date: Tue, 19 Mar 2024 14:58:33 -0700 Message-ID: <20240319215915.832127-8-samuel.holland@sifive.com> X-Mailer: git-send-email 2.43.1 In-Reply-To: <20240319215915.832127-1-samuel.holland@sifive.com> References: <20240319215915.832127-1-samuel.holland@sifive.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240319_145929_392748_67D3F959 X-CRM114-Status: GOOD ( 24.31 ) 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 When pointer masking is enabled for userspace, the kernel can accept tagged pointers as arguments to some system calls. Allow this by untagging the pointers in access_ok() and the uaccess routines. The software untagging in the uaccess routines is required because U-mode and S-mode have entirely separate pointer masking configurations. Signed-off-by: Samuel Holland --- arch/riscv/include/asm/processor.h | 1 + arch/riscv/include/asm/uaccess.h | 40 +++++++++++++++++++++--- arch/riscv/kernel/process.c | 49 +++++++++++++++++++++++++++++- 3 files changed, 84 insertions(+), 6 deletions(-) diff --git a/arch/riscv/include/asm/processor.h b/arch/riscv/include/asm/processor.h index 64b34e839802..cdc8569b2118 100644 --- a/arch/riscv/include/asm/processor.h +++ b/arch/riscv/include/asm/processor.h @@ -124,6 +124,7 @@ struct thread_struct { struct __riscv_v_ext_state vstate; unsigned long align_ctl; struct __riscv_v_ext_state kernel_vstate; + u8 pmlen; }; /* Whitelist the fstate from the task_struct for hardened usercopy */ diff --git a/arch/riscv/include/asm/uaccess.h b/arch/riscv/include/asm/uaccess.h index ec0cab9fbddd..ed282dcf9a6d 100644 --- a/arch/riscv/include/asm/uaccess.h +++ b/arch/riscv/include/asm/uaccess.h @@ -9,8 +9,38 @@ #define _ASM_RISCV_UACCESS_H #include +#include #include /* for TASK_SIZE */ +#ifdef CONFIG_RISCV_ISA_POINTER_MASKING +static inline unsigned long __untagged_addr(unsigned long addr) +{ + if (riscv_has_extension_unlikely(RISCV_ISA_EXT_SxNPM)) { + u8 shift = current->thread.pmlen; + + /* + * Virtual addresses are sign-extended, while + * physical addresses are zero-extended. + */ + if (IS_ENABLED(CONFIG_MMU)) + return (long)(addr << shift) >> shift; + else + return (addr << shift) >> shift; + } + + return addr; +} + +#define untagged_addr(addr) ({ \ + unsigned long __addr = (__force unsigned long)(addr); \ + (__force __typeof__(addr))__untagged_addr(__addr); \ +}) + +#define access_ok(addr, size) likely(__access_ok(untagged_addr(addr), size)) +#else +#define untagged_addr(addr) addr +#endif + /* * User space memory access functions */ @@ -130,7 +160,7 @@ do { \ */ #define __get_user(x, ptr) \ ({ \ - const __typeof__(*(ptr)) __user *__gu_ptr = (ptr); \ + const __typeof__(*(ptr)) __user *__gu_ptr = untagged_addr(ptr); \ long __gu_err = 0; \ \ __chk_user_ptr(__gu_ptr); \ @@ -246,7 +276,7 @@ do { \ */ #define __put_user(x, ptr) \ ({ \ - __typeof__(*(ptr)) __user *__gu_ptr = (ptr); \ + __typeof__(*(ptr)) __user *__gu_ptr = untagged_addr(ptr); \ __typeof__(*__gu_ptr) __val = (x); \ long __pu_err = 0; \ \ @@ -293,13 +323,13 @@ unsigned long __must_check __asm_copy_from_user(void *to, static inline unsigned long raw_copy_from_user(void *to, const void __user *from, unsigned long n) { - return __asm_copy_from_user(to, from, n); + return __asm_copy_from_user(to, untagged_addr(from), n); } static inline unsigned long raw_copy_to_user(void __user *to, const void *from, unsigned long n) { - return __asm_copy_to_user(to, from, n); + return __asm_copy_to_user(untagged_addr(to), from, n); } extern long strncpy_from_user(char *dest, const char __user *src, long count); @@ -314,7 +344,7 @@ unsigned long __must_check clear_user(void __user *to, unsigned long n) { might_fault(); return access_ok(to, n) ? - __clear_user(to, n) : n; + __clear_user(untagged_addr(to), n) : n; } #define __get_kernel_nofault(dst, src, type, err_label) \ diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c index 3578e75f4aa4..36129040b7bd 100644 --- a/arch/riscv/kernel/process.c +++ b/arch/riscv/kernel/process.c @@ -162,6 +162,7 @@ static void flush_tagged_addr_state(void) return; current->thread.envcfg &= ~ENVCFG_PMM; + current->thread.pmlen = 0; sync_envcfg(current); #endif @@ -255,9 +256,14 @@ void __init arch_task_cache_init(void) static bool have_user_pmlen_7; static bool have_user_pmlen_16; +/* + * Control the relaxed ABI allowing tagged user addresses into the kernel. + */ +static unsigned int tagged_addr_disabled; + long set_tagged_addr_ctrl(struct task_struct *task, unsigned long arg) { - unsigned long valid_mask = PR_PMLEN_MASK; + unsigned long valid_mask = PR_PMLEN_MASK | PR_TAGGED_ADDR_ENABLE; struct thread_info *ti = task_thread_info(task); u8 pmlen; @@ -288,12 +294,25 @@ long set_tagged_addr_ctrl(struct task_struct *task, unsigned long arg) return -EINVAL; } + /* + * Do not allow the enabling of the tagged address ABI if globally + * disabled via sysctl abi.tagged_addr_disabled, if pointer masking + * is disabled for userspace. + */ + if (arg & PR_TAGGED_ADDR_ENABLE && (tagged_addr_disabled || !pmlen)) + return -EINVAL; + task->thread.envcfg &= ~ENVCFG_PMM; if (pmlen == 7) task->thread.envcfg |= ENVCFG_PMM_PMLEN_7; else if (pmlen == 16) task->thread.envcfg |= ENVCFG_PMM_PMLEN_16; + if (arg & PR_TAGGED_ADDR_ENABLE) + task->thread.pmlen = pmlen; + else + task->thread.pmlen = 0; + if (task == current) sync_envcfg(current); @@ -308,6 +327,13 @@ long get_tagged_addr_ctrl(struct task_struct *task) if (is_compat_thread(ti)) return -EINVAL; + if (task->thread.pmlen) + ret = PR_TAGGED_ADDR_ENABLE; + + /* + * The task's pmlen is only set if the tagged address ABI is enabled, + * so the effective PMLEN must be extracted from envcfg.PMM. + */ switch (task->thread.envcfg & ENVCFG_PMM) { case ENVCFG_PMM_PMLEN_7: ret |= FIELD_PREP(PR_PMLEN_MASK, 7); @@ -326,6 +352,24 @@ static bool try_to_set_pmm(unsigned long value) return (csr_read_clear(CSR_ENVCFG, ENVCFG_PMM) & ENVCFG_PMM) == value; } +/* + * Global sysctl to disable the tagged user addresses support. This control + * only prevents the tagged address ABI enabling via prctl() and does not + * disable it for tasks that already opted in to the relaxed ABI. + */ + +static struct ctl_table tagged_addr_sysctl_table[] = { + { + .procname = "tagged_addr_disabled", + .mode = 0644, + .data = &tagged_addr_disabled, + .maxlen = sizeof(int), + .proc_handler = proc_dointvec_minmax, + .extra1 = SYSCTL_ZERO, + .extra2 = SYSCTL_ONE, + }, +}; + static int __init tagged_addr_init(void) { if (!riscv_has_extension_unlikely(RISCV_ISA_EXT_SxNPM)) @@ -339,6 +383,9 @@ static int __init tagged_addr_init(void) have_user_pmlen_7 = try_to_set_pmm(ENVCFG_PMM_PMLEN_7); have_user_pmlen_16 = try_to_set_pmm(ENVCFG_PMM_PMLEN_16); + if (!register_sysctl("abi", tagged_addr_sysctl_table)) + return -EINVAL; + return 0; } core_initcall(tagged_addr_init);