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s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=IkuD9zPPDPrNqKOg+1EuZo5HlTMskU88lY/hO73XGBQ=; b=Cxqy3B+zh5EVMpdKKt4kUhM4D527FSX3BnzQ7phhU8Ttyhlcc/q7kuehxaaix1TLcv cA1B2kk8y6uKDrbeq30/oDkt8AGbiVfZZOrh2bjO3zWfvvg7V2sJMJyWOBfksv0zPWkU 3lAWcduQNWXl6onvjRBLM6Cxz3y3UYtUmU7yEPmJoPFRrZrQxq0xdO00HC55Mo7hkKfr FlByezj7XGpH2WGEDyaLM7VhrSBuGDe60nTY1ui4puORMmBxyj0lmK1dXqDlvF/i0md1 9dX8KSdYk8HS0Z5fw5Vi6Rd3+7v6czzf5kaZGy4mOWC5qByp9DGl+MlGRbkK62IPYu2x PQWw== X-Gm-Message-State: APjAAAVVErmO1xTLitBU0YaD6M3m5curskdVZ8OnEkfnda/t9M/7w5lL nQAyOu9Uvz1c7qUof/2yVl+OwxVrdhK9H7eUOvyDzCr/wSYDC6+bNLxf5Zxk1a97e3MH+29JmF2 ND0uW3ZCzuBYSOT6eC1NimSryEl8E8vz5/AL4xAMCCNi94StFRLcsP3Fhu1Kyyt5zw2SgrC7Npt EJYMcNpeiBFYj50Vs= 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 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190430_062526_057432_C02D0FB2 X-CRM114-Status: GOOD ( 13.60 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Koenig@google.com, Szabolcs Nagy , Catalin Marinas , Will Deacon , Kostya Serebryany , Chintan Pandya , Felix , Vincenzo Frascino , Jacob Bramley , Leon Romanovsky , Kuehling@google.com, Dave Martin , Evgeniy Stepanov , Kevin Brodsky , Kees Cook , Ruben Ayrapetyan , Andrey Konovalov , Ramana Radhakrishnan , Deucher@google.com, Alex Williamson , Mauro Carvalho Chehab , Dmitry Vyukov , Greg Kroah-Hartman , Yishai Hadas , Jens Wiklander , Lee Smith , Alexander , Andrew Morton , Robin Murphy , Christian , Luc Van Oostenryck Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org 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();