From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pg1-f170.google.com (mail-pg1-f170.google.com [209.85.215.170]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 32666623 for ; Sun, 15 May 2022 03:19:52 +0000 (UTC) Received: by mail-pg1-f170.google.com with SMTP id a191so11081479pge.2 for ; Sat, 14 May 2022 20:19:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to; bh=MEi80uS+Hv7whcnPDmWumoTBr+8suRXlPOFaSGMgA4w=; b=k2E2gWVeuIcJmXctth50gI+JpHO8Jdri7XEy81BsIY5b7LBB+U+mfEZEpjht24f6UP dpH1IzclL/xXavJ7dhUZAwraqMh5bh6+PNchYFKigMWuFKoAjMlY5pRxsSmlGENEVH77 eDbavVNzNaxKdVIVDHOBiq7SWRKR8gbONOzLo= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=MEi80uS+Hv7whcnPDmWumoTBr+8suRXlPOFaSGMgA4w=; b=QfMSJEMm5qElBvHLJvZYIPjJngeP4/oyZc3Q8R/oj4dKwOJzBZBDIXbE1KKLPLtU8X 9NIEXMHT/OhBDIkY/hflfoZBcrkx3evsO+hxrlsK+vRIE7UsHXq47mrVwBHUOEgPLbYQ Ron5C++WWxQGpDLJe/ccPYNU8T5HnZGkoqtIjCl6MrEmLuIzg0KpCqcO+JbkBmMwsWM7 UFzKbPfOZJkjdEThep3ClNZmKNjVdaLZdiMhjHBFkUnm67BMoqUpi/xIgR7wX8avfgYy SnQA10vW8PiuvNcwHw8r3i5a/JdHlLCJjZzJgmImBfY9ZS2oD4jgNeHFcP7AQ3QUfHtV 1hJw== X-Gm-Message-State: AOAM531gfQKUkfxRdcuZWzt1WB2Nqzyf2MrNnL/92UmjnYGiFVKn8OzY J0aASIFfvpBusG0tIA4DVrL8vg== X-Google-Smtp-Source: ABdhPJwR7XZOxJrS4oIzgQbamR8MN0/jGNaXZitp2YdTHflXf1xkjcnFI+uVSj0ggVkl4+1JzhTJtw== X-Received: by 2002:a63:8843:0:b0:3da:fe5c:9374 with SMTP id l64-20020a638843000000b003dafe5c9374mr10329905pgd.342.1652584791498; Sat, 14 May 2022 20:19:51 -0700 (PDT) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id o15-20020a170902d4cf00b0015e8d4eb27csm4411356plg.198.2022.05.14.20.19.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 14 May 2022 20:19:51 -0700 (PDT) Date: Sat, 14 May 2022 20:19:47 -0700 From: Kees Cook To: Sami Tolvanen Cc: linux-kernel@vger.kernel.org, Josh Poimboeuf , Peter Zijlstra , x86@kernel.org, Catalin Marinas , Will Deacon , Mark Rutland , Nathan Chancellor , Nick Desaulniers , Joao Moreira , Sedat Dilek , Steven Rostedt , linux-hardening@vger.kernel.org, linux-arm-kernel@lists.infradead.org, llvm@lists.linux.dev Subject: Re: [RFC PATCH v2 20/21] x86: Add support for CONFIG_CFI_CLANG Message-ID: <202205142016.DB5DB8638A@keescook> References: <20220513202159.1550547-1-samitolvanen@google.com> <20220513202159.1550547-21-samitolvanen@google.com> Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20220513202159.1550547-21-samitolvanen@google.com> On Fri, May 13, 2022 at 01:21:58PM -0700, Sami Tolvanen wrote: > With CONFIG_CFI_CLANG, the compiler injects a type preamble > immediately before each function and a check to validate the target > function type before indirect calls: > > ; type preamble > __cfi_function: > int3 > int3 > mov , %eax > int3 > int3 > function: > ... > ; indirect call check > cmpl    , -6(%r11) > je .Ltmp1 > ud2 > .Ltmp1: > call __x86_indirect_thunk_r11 > > Define the __CFI_TYPE helper macro for manual type annotations in > assembly code, add error handling for the CFI ud2 traps, and allow > CONFIG_CFI_CLANG to be selected on x86_64. > > Signed-off-by: Sami Tolvanen Looks good testing with LKDTM... $ echo CFI_FORWARD_PROTO | cat >/sys/kernel/debug/provoke-crash/DIRECT [ 144.084017] lkdtm: Performing direct entry CFI_FORWARD_PROTO [ 144.086138] lkdtm: Calling matched prototype ... [ 144.087833] lkdtm: Calling mismatched prototype ... [ 144.089777] CFI failure at lkdtm_CFI_FORWARD_PROTO+0x34/0x67 [lkdtm] (target: lkdtm_increment_int+0x0/0x7 [lkdtm]; expected type: 0x7e0c52a5) Tested-by: Kees Cook -- Kees Cook