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Tue, 2 Jun 2026 12:34:46 +0000 (GMT) Message-ID: <5c52effb1b4723c025f478c1c902bf83a9a4d0ed.camel@linux.ibm.com> Subject: Re: [PATCH v5 3/4] security: ima: rename boot_aggregate when ima is initialised at late_sync From: Mimi Zohar To: Yeoreum Yun , linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, linux-integrity@vger.kernel.org Cc: paul@paul-moore.com, roberto.sassu@huaweicloud.com, noodles@earth.li, jarkko@kernel.org, sudeep.holla@kernel.org, jmorris@namei.org, serge@hallyn.com, dmitry.kasatkin@gmail.com, eric.snowberg@oracle.com, jgg@ziepe.ca, Jonathan McDowell In-Reply-To: <20260601142749.3379697-4-yeoreum.yun@arm.com> References: <20260601142749.3379697-1-yeoreum.yun@arm.com> <20260601142749.3379697-4-yeoreum.yun@arm.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Date: Tue, 02 Jun 2026 08:34:46 -0400 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Evolution 3.58.3 (3.58.3-1.fc43) X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNjAyMDExNiBTYWx0ZWRfX1/g8jRMrdEqv uNuQEWTLvwXkTguwemDuuHjFSmCo28NRSpxFGZAKfaB40FxGsWQkR07NQSklJd8BqHkgtcRYEWM MVABDTJNNUEK3B1I5zKJMLfz5RaSaphs55EzERpFuUdbWsAyfHMllNGWpMY1q49SYrji52IUQrc cto/HNPbJkmdAcj1OElbAB1xLNJN5rjT9Tn9ntF+489lemXz6lbrycuPgVkmS2XcRmbj4/J8bCq Li6i8FvC4p4k9OQdWBebgIbZ4erBUChfvDpsMY13U5WIh7m7QoRhDSpc6x1T/JVhAuYP1fWrN7Y D/aCZTP9oN1Ley8TX6znflnVmZpgxXeLvKDTyDjlonQh8hOap7RjWhIj+RaYWNwZBCT7Rh7wJ97 tWQKvUBnP7q+qSRLmvuA4gQXDrtx1aJNrkFtDOwJIieHYOnS3fR9yWzz54Iy29AdUswSV3x/YR/ agsYm42w4A1vqayI4ww== X-Proofpoint-GUID: elNur2XUZmHeE_jFM2AyFLxQR1gRuSEA X-Proofpoint-ORIG-GUID: e3S1vITmyF5br7guAq4kaHB0EKSozwiI X-Authority-Analysis: v=2.4 cv=DZknbPtW c=1 sm=1 tr=0 ts=6a1ecdea cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=IkcTkHD0fZMA:10 a=FelO9ux0wxsA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=VabnemYjAAAA:8 a=7CQSdrXTAAAA:8 a=DDGuNG6xrOoNSW4XS2IA:9 a=QEXdDO2ut3YA:10 a=gKebqoRLp9LExxC7YDUY:22 a=a-qgeE7W1pNrGK8U0ZQC:22 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.125,FMLib:17.12.100.49 definitions=2026-06-02_01,2026-05-28_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 clxscore=1015 suspectscore=0 impostorscore=0 lowpriorityscore=0 phishscore=0 malwarescore=0 priorityscore=1501 bulkscore=0 adultscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605210000 definitions=main-2606020116 On Mon, 2026-06-01 at 15:27 +0100, Yeoreum Yun wrote: > From: Jonathan McDowell >=20 > The Linux IMA (Integrity Measurement Architecture) subsystem used for > secure boot, file integrity, or remote attestation cannot be a loadable > module for few reasons listed below: >=20 > o Boot-Time Integrity: IMA=E2=80=99s main role is to measure and apprais= e files > before they are used. This includes measuring critical system files > during early boot (e.g., init, init scripts, login binaries). If IMA > were a module, it would be loaded too late to cover those. >=20 > o TPM Dependency: IMA integrates tightly with the TPM to record > measurements into PCRs. The TPM must be initialized early (ideally > before init_ima()), which aligns with IMA being built-in. >=20 > o Security Model: IMA is part of a Trusted Computing Base (TCB). Making > it a module would weaken the security model, as a potentially > compromised system could delay or tamper with its initialization. >=20 > IMA must be built-in to ensure it starts measuring from the earliest > possible point in boot which inturn implies TPM must be initialised and > ready to use before IMA. >=20 > Unfortunately some TPM drivers (such as Arm FF-A, or SPI attached TPM > devices) are not reliably available during the initcall_late stage, > resulting in a log error: >=20 > ima: No TPM chip found, activating TPM-bypass! >=20 > To address this issue, IMA_INIT_LATE_SYNC is introduced. > However, a remote attestation service cannot determine when IMA has been > initialized because the boot_aggregate measurement name remains unchanged= , > even though IMA is initialized later at late_initcall_sync when > IMA_INIT_LATE_SYNC is enabled. >=20 > Therefore, use a distinct boot_aggregate name when IMA_INIT_LATE_SYNC > is enabled, allowing the remote attestation service to identify > when IMA has been initialized. >=20 > Signed-off-by: Jonathan McDowell > [yeoreum.yun@arm.com: modified to align with the IMA_INIT_LATE_SYNC chang= e] Thanks, Yeoreum. This version requires your Signed-off-by tag as well as Jonathan's. Otherwise the patch looks good. Mimi