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[209.85.220.73]) by mx.google.com with SMTPS id f16sor5687550vsl.71.2019.06.24.07.33.07 for (Google Transport Security); Mon, 24 Jun 2019 07:33:07 -0700 (PDT) Received-SPF: pass (google.com: domain of 3i98qxqokcbqu7xbyi47f508805y.w86527eh-664fuw4.8b0@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=daRRCGEX; spf=pass (google.com: domain of 3i98qxqokcbqu7xbyi47f508805y.w86527eh-664fuw4.8b0@flex--andreyknvl.bounces.google.com designates 209.85.220.73 as permitted sender) smtp.mailfrom=3I98QXQoKCBQu7xByI47F508805y.w86527EH-664Fuw4.8B0@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=OFC24w2VYFjptSxPqCpbBEqhaUlc2rZ4vtg/DxWHKUY=; b=daRRCGEXfLHGLUQo//HRDLfqaBO4lfL42FrfPGRnRKOhn1XL6qGzvLE8amzWfXer5a WhALrZBTuSnnuN10/CaZpZqQ5oMU4MQefeNJm/AP0b4uEXgK32RunU93durvNp8XKKHL uQfK0a3nA5oC/DUYeVxUqLVQFd9uJpb2OtV7FV9mAWqDzJacQiBSNlyVGMSQHbzkOff3 MC+xIW6PfIq1tVQloxoUTZ3GncOdewoLB+fLV/jb+kaJgM+7s5iRXhY273LkR2goOH7a Ap1pVnJAk4onxG8CZjucr85/ku+lb+LecGyuZhueMHSpk8X8CCgAIxuGrhQgzxcP8FnL C2Sw== X-Google-Smtp-Source: APXvYqztHTWRHYOC83H4IfNbENBsJMJpCmuVpe91PkFE56CWhu5KbIzw0hmUvviWu8/4yX8wEpc7iI+Lm7IC+LHT X-Received: by 2002:a67:6e44:: with SMTP id j65mr66559877vsc.132.1561386787480; Mon, 24 Jun 2019 07:33:07 -0700 (PDT) Date: Mon, 24 Jun 2019 16:32:46 +0200 In-Reply-To: Message-Id: <98cbd89549395d372a4a20ab2ac536bf19d37e52.1561386715.git.andreyknvl@google.com> Mime-Version: 1.0 References: X-Mailer: git-send-email 2.22.0.410.gd8fdbe21b5-goog Subject: [PATCH v18 01/15] 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 , Luc Van Oostenryck , Dave Martin , Khalid Aziz , enh , Jason Gunthorpe , Christoph Hellwig , Dmitry Vyukov , Kostya Serebryany , Evgeniy Stepanov , Lee Smith , Ramana Radhakrishnan , Jacob Bramley , Ruben Ayrapetyan , Robin Murphy , 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 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: Vincenzo Frascino Reviewed-by: Kees Cook Reviewed-by: Catalin Marinas Signed-off-by: Andrey Konovalov --- arch/arm64/include/asm/uaccess.h | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h index 5a1c32260c1f..a138e3b4f717 100644 --- a/arch/arm64/include/asm/uaccess.h +++ b/arch/arm64/include/asm/uaccess.h @@ -62,6 +62,8 @@ static inline unsigned long __range_ok(const void __user *addr, unsigned long si { unsigned long ret, limit = current_thread_info()->addr_limit; + addr = untagged_addr(addr); + __chk_user_ptr(addr); asm volatile( // A + B <= C + 1 for all A,B,C, in four easy steps: @@ -215,7 +217,8 @@ 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) @@ -223,10 +226,11 @@ 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();