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[209.85.220.73]) by mx.google.com with SMTPS id b2sor3704075otp.66.2019.05.06.09.31.13 for (Google Transport Security); Mon, 06 May 2019 09:31:13 -0700 (PDT) Received-SPF: pass (google.com: domain of 3uwhqxaokceierhvi2orzpksskpi.gsqpmry1-qqozego.svk@flex--andreyknvl.bounces.google.com designates 209.85.220.73 as permitted sender) client-ip=209.85.220.73; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=rAOt6QkM; spf=pass (google.com: domain of 3uwhqxaokceierhvi2orzpksskpi.gsqpmry1-qqozego.svk@flex--andreyknvl.bounces.google.com designates 209.85.220.73 as permitted sender) smtp.mailfrom=3UWHQXAoKCEIerhvi2orzpksskpi.gsqpmry1-qqozego.svk@flex--andreyknvl.bounces.google.com; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=/Xcm/dv07E6tB6Fg+Bd1uLrNx0q2WagwUZqys5y8XCQ=; b=rAOt6QkMD/QKlKVog82fKw84EsQnaASzO/nI8W5EIDbrmmjV3gr6+15mZ10SMb6Rf5 i/ZniLNvWV//CPRfADxSnSKtN/6Gg017m4Gik6Cenllh7RN6CfI/AKj72maW2yKQfmpN GrE1GcO1EKZaX0U+I3FWYiw4misL8V2knxuMTZnhd7+ifYq/drNNa4087ayYcqsu4RzV YnDg0sSjmZfX/PgQJ/vdVYIZT3u95MTKmAQy8Dfp2UhL6OXfBsqkSnVsPRCgY0ZcNTeM d3f8I7eWT+VKLfqWWZufhZUUDge/eC39ycIbKQ1fqVyQEg05Z5H0MBzHuW0wC/j81BOZ a7SA== X-Google-Smtp-Source: APXvYqwsU29/a5rUuddp5tcfbPS3CQhzs1NWwE9FVJC7oUUpeYui7bu7Qsrr1jpZGFt27bCra6fHy1EBLcG5J9Rk X-Received: by 2002:a9d:4917:: with SMTP id e23mr17423724otf.63.1557160273461; Mon, 06 May 2019 09:31:13 -0700 (PDT) Date: Mon, 6 May 2019 18:30:48 +0200 In-Reply-To: Message-Id: <02e1242715cc1bf23a139e5e8152fb4feaa4b41d.1557160186.git.andreyknvl@google.com> Mime-Version: 1.0 References: X-Mailer: git-send-email 2.21.0.1020.gf2820cf01a-goog Subject: [PATCH v15 02/17] arm64: untag user pointers in access_ok and __uaccess_mask_ptr From: Andrey Konovalov To: linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-rdma@vger.kernel.org, linux-media@vger.kernel.org, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org Cc: Catalin Marinas , Vincenzo Frascino , Will Deacon , Mark Rutland , Andrew Morton , Greg Kroah-Hartman , Kees Cook , Yishai Hadas , Felix Kuehling , Alexander Deucher , Christian Koenig , Mauro Carvalho Chehab , Jens Wiklander , Alex Williamson , Leon Romanovsky , Dmitry Vyukov , Kostya Serebryany , Evgeniy Stepanov , Lee Smith , Ramana Radhakrishnan , Jacob Bramley , Ruben Ayrapetyan , Robin Murphy , Luc Van Oostenryck , Dave Martin , Kevin Brodsky , Szabolcs Nagy , Andrey Konovalov Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: This patch is a part of a series that extends arm64 kernel ABI to allow to pass tagged user pointers (with the top byte set to something else other than 0x00) as syscall arguments. copy_from_user (and a few other similar functions) are used to copy data from user memory into the kernel memory or vice versa. Since a user can provided a tagged pointer to one of the syscalls that use copy_from_user, we need to correctly handle such pointers. Do this by untagging user pointers in access_ok and in __uaccess_mask_ptr, before performing access validity checks. Note, that this patch only temporarily untags the pointers to perform the checks, but then passes them as is into the kernel internals. Reviewed-by: Catalin Marinas Signed-off-by: Andrey Konovalov --- arch/arm64/include/asm/uaccess.h | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h index e5d5f31c6d36..9164ecb5feca 100644 --- a/arch/arm64/include/asm/uaccess.h +++ b/arch/arm64/include/asm/uaccess.h @@ -94,7 +94,7 @@ static inline unsigned long __range_ok(const void __user *addr, unsigned long si return ret; } -#define access_ok(addr, size) __range_ok(addr, size) +#define access_ok(addr, size) __range_ok(untagged_addr(addr), size) #define user_addr_max get_fs #define _ASM_EXTABLE(from, to) \ @@ -226,7 +226,8 @@ static inline void uaccess_enable_not_uao(void) /* * Sanitise a uaccess pointer such that it becomes NULL if above the - * current addr_limit. + * current addr_limit. In case the pointer is tagged (has the top byte set), + * untag the pointer before checking. */ #define uaccess_mask_ptr(ptr) (__typeof__(ptr))__uaccess_mask_ptr(ptr) static inline void __user *__uaccess_mask_ptr(const void __user *ptr) @@ -234,10 +235,11 @@ static inline void __user *__uaccess_mask_ptr(const void __user *ptr) void __user *safe_ptr; asm volatile( - " bics xzr, %1, %2\n" + " bics xzr, %3, %2\n" " csel %0, %1, xzr, eq\n" : "=&r" (safe_ptr) - : "r" (ptr), "r" (current_thread_info()->addr_limit) + : "r" (ptr), "r" (current_thread_info()->addr_limit), + "r" (untagged_addr(ptr)) : "cc"); csdb(); -- 2.21.0.1020.gf2820cf01a-goog