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Wed, 31 Jan 2024 14:52:46 GMT Received: from smtpav06.wdc07v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 5260C58054; Wed, 31 Jan 2024 14:52:46 +0000 (GMT) Received: from smtpav06.wdc07v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 2CBE55803F; Wed, 31 Jan 2024 14:52:45 +0000 (GMT) Received: from [9.47.158.152] (unknown [9.47.158.152]) by smtpav06.wdc07v.mail.ibm.com (Postfix) with ESMTP; Wed, 31 Jan 2024 14:52:45 +0000 (GMT) Message-ID: <015c3a14-0d23-43ba-9593-3d4ff588f1bb@linux.ibm.com> Date: Wed, 31 Jan 2024 09:52:44 -0500 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 0/5] evm: Support signatures on stacked filesystem Content-Language: en-US To: Amir Goldstein Cc: linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, linux-unionfs@vger.kernel.org, linux-kernel@vger.kernel.org, paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com, zohar@linux.ibm.com, roberto.sassu@huawei.com, miklos@szeredi.hu References: <20240130214620.3155380-1-stefanb@linux.ibm.com> From: Stefan Berger In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed X-TM-AS-GCONF: 00 X-Proofpoint-GUID: baJzSSSfc6NAr5gdJX5P92ig7rAHEN-1 X-Proofpoint-ORIG-GUID: 9_azz8zb9r4UUIFse6vB9B3KaEx7v_Sr Content-Transfer-Encoding: 8bit X-Proofpoint-UnRewURL: 0 URL was un-rewritten Precedence: bulk X-Mailing-List: linux-integrity@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.272,Aquarius:18.0.1011,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2024-01-31_08,2024-01-31_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 clxscore=1015 spamscore=0 malwarescore=0 bulkscore=0 mlxscore=0 priorityscore=1501 phishscore=0 adultscore=0 impostorscore=0 suspectscore=0 mlxlogscore=976 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2311290000 definitions=main-2401310114 On 1/31/24 08:18, Amir Goldstein wrote: > On Tue, Jan 30, 2024 at 11:46 PM Stefan Berger wrote: >> >> EVM has recently been completely disabled on unsupported (e.g., >> overlayfs). This series now enables copy-up of "portable and immutable" >> signatures on those filesystems and enables the enforcement of >> "portable and immutable" as well as the "original" signatures on >> previously unsupported filesystem when EVM is enabled with EVM_INIT_X509. >> HMAC verification and generation remains disabled on those filesystems. >> > > I am missing a high level description of what is in those "portable > and immutable" > signatures and how those signatures remain valid across copy up. > From 2/5: "Portable and immutable EVM signatures can be copied up by stacked file- system since the metadata their signature covers does not include file- system-specific data such as a file's inode number, generation, and UUID." Instead, the signatures cover file metadata such as file mode bits, uid, and gid as well as xattrs, which can all be preserved unchanged across a copy-up. Reference: https://elixir.bootlin.com/linux/v6.7.2/source/security/integrity/evm/evm_crypto.c#L169 > Thanks, > Amir. >