From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2A96F370D45; Tue, 3 Mar 2026 16:38:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772555923; cv=none; b=O8PgM67IxvNEQR3Tdnon0/O8aL2pPHFyJEuFp6GE0t66AWD7wtuTAdkQl3kUWPXrIWE/QFTOeCSUZbgQThMsIk2K3G7GBRy8mPEVvmI27PPpjcRUMd85tRH93Car2YBPPwu+UOpyWD154gbHyGh/eaNxJoMxR1yUH+wUn4YUCCQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772555923; c=relaxed/simple; bh=lxeNyqMRRI9fL4eYmbH8oZ+nwJE9/XGPxmznsDIrVC4=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=PlB99gUF8r19EpW/Al818INv7YRpynHtAg+c8DH/I4a5FnnXRLp/8CIdJtNPzUT2IZsB5eQ9P0JV1t9ifJ1uSNQGoLTxd3cfEnh2BHuY98lIcExvcoKLQioPUM67td6m0Ndv8wDDEKuWawZSU8YpQJTvq0+ACE9UQkD6mPQQXFY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=jrmrh/Uf; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="jrmrh/Uf" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 766E9C116C6; Tue, 3 Mar 2026 16:38:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772555922; bh=lxeNyqMRRI9fL4eYmbH8oZ+nwJE9/XGPxmznsDIrVC4=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=jrmrh/UfdXRmDeQFjkuIaJKOltOxNdbFhfXFSkPKITeXW0OSp8csrG6TrjyAqcMha 7JssawiTsRd/p1E5crBihv2t+kaJlcDARtXw4GAGkccnjyisEdEI0WsuV6cVjgqOzv cMPAAJa+sa8jmfhpExDMHcNuIUWk1M+4cBMYSWvomfQQ8EQTVtOYOHNF3AYlLdTeLF LhyMiE7HH+zSqgUt9lNHxkhW4TUaGpj4RlhU8runUP7L0PB6tc3VSwEVxvW7mZRKe2 fM0izilv5esqNgr7g2JiBU6+Vf7yCN4oUZTBf2vhjSacCAExH+WLTWprW9H4FTeh2S ujywis8EiKOZA== X-Mailer: emacs 30.2 (via feedmail 11-beta-1 I) From: Aneesh Kumar K.V To: Dan Williams , linux-coco@lists.linux.dev, linux-pci@vger.kernel.org Cc: gregkh@linuxfoundation.org, aik@amd.com, yilun.xu@linux.intel.com, bhelgaas@google.com, alistair23@gmail.com, lukas@wunner.de, jgg@nvidia.com, Donald Hunter , Jakub Kicinski Subject: Re: [PATCH v2 08/19] PCI/TSM: Add "evidence" support In-Reply-To: <20260303000207.1836586-9-dan.j.williams@intel.com> References: <20260303000207.1836586-1-dan.j.williams@intel.com> <20260303000207.1836586-9-dan.j.williams@intel.com> Date: Tue, 03 Mar 2026 22:08:34 +0530 Message-ID: Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain Dan Williams writes: > Once one accepts the threat model that devices may be adversarial the > process of establishing trust in the device identity, the integrity + > confidentiality of its link, and the integrity + confidentiality of its > MMIO interface requires multiple evidence objects from the device. The > device's certificate chain, measurements and interface report need to be > retrieved by the host, validated by the TSM and transmitted to the guest > all while mitigating TOCTOU races. > > All TSM implementations share the same fundamental objects, but vary in how > the TSM conveys its trust in the objects. Some TSM implementations expect > the full documents to be conveyed over untrustworthy channels while the TSM > securely conveys a digest. Others transmit full objects with signed SPDM > transcripts of requester provided nonces. Some offer a single transcript > to convey the version, capabilities, and algorithms (VCA) data and > measurements in one blob while others split VCA as a separate signed blob. > > Introduce a netlink interface to dump all these objects in a common way > across TSM implementations and across host and guest environments. > Userspace is responsible for handling the variance of "TSM provides combo > measurements + VCA + nonce + signature, vs TSM provides a digest over a > secure channel of the same". > > The implementation adheres to the guideline from: > Documentation/userspace-api/netlink/genetlink-legacy.rst > > New Netlink families should never respond to a DO operation with > multiple replies, with ``NLM_F_MULTI`` set. Use a filtered dump > instead. > > Per SPDM, transcripts may grow to be 16MB in size. Large PCI/TSM netlink > blobs are handled via a sequence of dump messages that userspace must > concatenate. > Should we also expose evidence->generation to userspace so it can be used during accept()? This would allow us to ensure that the device is accepted using the same evidence generation observed by userspace. -aneesh