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[209.85.220.73]) by mx.google.com with SMTPS id b23sor11810188pgb.41.2019.04.30.06.25.24 for (Google Transport Security); Tue, 30 Apr 2019 06:25:24 -0700 (PDT) Received-SPF: pass (google.com: domain of 3w0zixaokcgoivlzmgsvdtowwotm.kwutqvcf-uusdiks.wzo@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=cjAZo1be; spf=pass (google.com: domain of 3w0zixaokcgoivlzmgsvdtowwotm.kwutqvcf-uusdiks.wzo@flex--andreyknvl.bounces.google.com designates 209.85.220.73 as permitted sender) smtp.mailfrom=3w0zIXAoKCGoIVLZMgSVdTOWWOTM.KWUTQVcf-UUSdIKS.WZO@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=IkuD9zPPDPrNqKOg+1EuZo5HlTMskU88lY/hO73XGBQ=; b=cjAZo1bevEgDG9f0Gp0lCqBUDVGf7WH9HfahHvPYK3yXKOMpkTJl6c0Qs/+BaViS4F SVbEHv0pbmF0M0fXn45Xz+XZ5NA51A6Q84gce81tqYq+4vQ4fSd4Vfr74XM9VMTqpEUn hpbIVHi0Y6E4lGzikQQHuG5LSWrNkshsuGLGjPRywGWJWT4PFmQUF2llhQi6ncC/Vlfh XyXZ2xzPVmh+mASSDoCOMBPHpUNh2v+x16jbihEdr4DI6v1V/jUL7ilAE/v54hqYIVN8 AFB4b6bLnE3ptsM0NTOpxh1giv5Af/8Vei/jZ/b9XgJhABJa8DnBXyZnippbFF98erxD 64TA== X-Google-Smtp-Source: APXvYqxwzeO4aaEq5t7dlXsyLEMZLxNA1xUAM/PWlhFhSshLHzTvKlXrQBr9Il+4R5AJQuOw/QR46XMvR3q8fhhC X-Received: by 2002:a65:534b:: with SMTP id w11mr7522791pgr.210.1556630723459; Tue, 30 Apr 2019 06:25:23 -0700 (PDT) Date: Tue, 30 Apr 2019 15:24:58 +0200 In-Reply-To: Message-Id: <29b7234f48a282037bdfc23e07ff167756fca0df.1556630205.git.andreyknvl@google.com> Mime-Version: 1.0 References: X-Mailer: git-send-email 2.21.0.593.g511ec345e18-goog Subject: [PATCH v14 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 , Kuehling@google.com, Felix , Deucher@google.com, Alexander , Koenig@google.com, Christian , 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 , Chintan Pandya , Luc Van Oostenryck , Dave Martin , Kevin Brodsky , Szabolcs Nagy , Andrey Konovalov 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: X-Virus-Scanned: ClamAV using ClamSMTP 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();