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a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=/Xcm/dv07E6tB6Fg+Bd1uLrNx0q2WagwUZqys5y8XCQ=; b=IJeYNn+lTuS9+5CK26LYNWT47Xzp3yAcKn0FwrJGf69xGUNtfGadUTYKWXTuW2BG3J vrLk0reWQMNxJDtEOsc738X9iw84ngee7Zhg1Cdi0+TfcCXksBG6U8hdiOV6KwFid1Ty psWObHINZilO22kewK5lOi/+Aok241T6uXtdCsZLetvvd3/8FQhwxKgNmdBvrlyevN06 43IFZ/6c7VaIdTxUGPGzm3Yddiee2AodZw0+HcULHtj7GIPh6GQxbbdbSjsIR8fqeyYZ g2rONJxU/MkG25Db3fQCNxNkonlHaW7rXAGw1mR9EDllTlAiS/xd9MyaHjyoHMyNDtgz tzew== X-Gm-Message-State: APjAAAVlbhVoYcHbc99uCMpX90i5DpjZMhyiDjPacFiw2HjfL0fa3RGM pn0GKaSVOFUs6HEYtFwZ9c3bZ7HUWH+OR08X7WBZVpLcsOstWTeHUzh+CaVpMy9wwVgwRw9zVCF f6rB4aaa1j9UhRg5cyMqLHTlZKeZ9l+KrUKtnYO0snISONVP9Jv9YRFJqMO6rnHfHjGQgpBvcOF KzfKuj1eLb5WkF1bw= 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 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190506_093115_695322_12D6BC2A X-CRM114-Status: GOOD ( 14.01 ) 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 , Szabolcs Nagy , Catalin Marinas , Will Deacon , Kostya Serebryany , Felix Kuehling , Vincenzo Frascino , Jacob Bramley , Leon Romanovsky , Dave Martin , Evgeniy Stepanov , Kevin Brodsky , Kees Cook , Ruben Ayrapetyan , Andrey Konovalov , Lee Smith , Alex Williamson , Mauro Carvalho Chehab , Dmitry Vyukov , Greg Kroah-Hartman , Yishai Hadas , Jens Wiklander , Ramana Radhakrishnan , Alexander Deucher , Andrew Morton , Robin Murphy , Christian Koenig , Luc Van Oostenryck Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel