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Thu, 7 May 2026 14:00:55 +0000 (GMT) Received: from li-43857255-d5e6-4659-90f1-fc5cee4750ad.ibm.com (unknown [9.61.30.146]) by smtpav04.dal12v.mail.ibm.com (Postfix) with ESMTP; Thu, 7 May 2026 14:00:55 +0000 (GMT) Message-ID: Subject: Re: [PATCH] ima: debugging late_initcall_sync measurements From: Mimi Zohar To: Roberto Sassu , Paul Moore Cc: Yeoreum Yun , Jonathan McDowell , linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, linux-integrity@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, jmorris@namei.org, serge@hallyn.com, roberto.sassu@huawei.com, dmitry.kasatkin@gmail.com, eric.snowberg@oracle.com, jarkko@kernel.org, jgg@ziepe.ca, sudeep.holla@kernel.org, maz@kernel.org, oupton@kernel.org, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, catalin.marinas@arm.com, will@kernel.org, noodles@meta.com, sebastianene@google.com In-Reply-To: <8c99263d8e63100e0b5e6c8cf739f7f6e7e79f6b.camel@huaweicloud.com> References: <7734099f5e7fda5480bca016a9e6707983325fbd.camel@linux.ibm.com> <9f188536f09a2db30877d6bfbb84aeaf2565cccf.camel@linux.ibm.com> <5debff82dc758d9c91223e4f1f5b9e39a3fcd4f5.camel@linux.ibm.com> <19dfb0e2730.2843.85c95baa4474aabc7814e68940a78392@paul-moore.com> <461ec995935e2b42a8414f6f87063ff2557bbfb4.camel@linux.ibm.com> <8c99263d8e63100e0b5e6c8cf739f7f6e7e79f6b.camel@huaweicloud.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Date: Thu, 07 May 2026 10:00:55 -0400 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Evolution 3.56.2 (3.56.2-2.fc42) X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTA3MDEzNiBTYWx0ZWRfXxfALLztlGl7O tSbUOVQ3WbBM1bCCw1QNc8e46+M02jlRVTzWpNfWqV4U4JYHyDBSb2F2Vj00SQKW1n/4sA6Cuge RLHY0vuM/M1XTJDJnGzrrF5HF0oLVqqXgzvkR7Ruexa1itwjH9dJZ/xyEiP4xo/6fF447binzzB 75wqfSNI7nok9TxDlUiRhfFQxu7TIM+X7JNVVY6I3bFW411fYwah3kBn8xu4wFlY5f8WkFtIF8G GHzgTjorO//v02HL0BQwnEv6Ywtq72RMr7rc1qXN6z/TwqniSLS/2Zy02CYKg1hrnxXdyfeaBkR IDalQF57kTg7knAnD3MdOB3f+orldz3xGdFCvxkl8QSHPPr8xdomE8Hgo1IGEAmMhO0hRfJhWVu 2+sU/An7SAhWiG+aHD8pW4yWeLMghEWvpGPxH5Y350JV7VRJRatU5ue+ERXEVT17nyQW0V5CQvD ltTOzRTGcHdMiptRffg== X-Proofpoint-ORIG-GUID: 4Ev7-NHEpeuk_LfgDJ-Qhn0RMmKkW_iI X-Proofpoint-GUID: IvDOIm6WvmeJI_VGRy5Jq49N0vizzzck X-Authority-Analysis: v=2.4 cv=W7UIkxWk c=1 sm=1 tr=0 ts=69fc9b1b cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=IkcTkHD0fZMA:10 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=uAbxVGIbfxUO_5tXvNgY:22 a=VnNF1IyMAAAA:8 a=eeChVw4XoIuzKrOC7zMA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-05-07_01,2026-05-06_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 adultscore=0 lowpriorityscore=0 malwarescore=0 suspectscore=0 spamscore=0 clxscore=1015 phishscore=0 bulkscore=0 impostorscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2604200000 definitions=main-2605070136 On Thu, 2026-05-07 at 10:10 +0200, Roberto Sassu wrote: > On Wed, 2026-05-06 at 22:25 -0400, Mimi Zohar wrote: > > On Tue, 2026-05-05 at 22:11 -0400, Paul Moore wrote: > > > On May 5, 2026 9:57:23 PM Mimi Zohar wrote: > > > > On Tue, 2026-05-05 at 18:55 -0400, Paul Moore wrote: > > > > > On Tue, May 5, 2026 at 5:05=E2=80=AFPM Mimi Zohar wrote: > > > > > > On Mon, 2026-05-04 at 16:51 -0400, Paul Moore wrote: > > > > > > > On Mon, May 4, 2026 at 8:03=E2=80=AFAM Mimi Zohar wrote: > > > > > > > > On Sun, 2026-05-03 at 12:46 -0400, Paul Moore wrote: > > > > > > > > > Regardless, assuming you always want IMA to leverage a TP= Ms when they > > > > > > > > > exist, your reply suggests that using an initcall based I= MA init > > > > > > > > > scheme, even a late-sync initcall, may not be sufficient = because > > > > > > > > > deferred TPM initialization could happen later, yes? > > > > > > > >=20 > > > > > > > > Well yeah. The TPM could be configured as a module, but th= at scenario is=20 > > > > > > > > not of > > > > > > > > interest. That's way too late. The case being addressed i= n this patch set is > > > > > > > > when the TPM driver tries to initialize at device_initcall,= returns > > > > > > > > EPROBE_DEFER, and is retried at deferred_probe_initcall (la= te_initcall). Since > > > > > > > > ordering within an initcall is not supported, this patch at= tempts to initialize > > > > > > > > IMA at late_initcall and similarly retries, in this case, a= t=20 > > > > > > > > late_initcall_sync. > > > > > > >=20 > > > > > > > Okay, so from a TPM initialization perspective you are satisf= ied with > > > > > > > a late-sync IMA initialization, yes? > > > > > >=20 > > > > > > No. On some architectures moving IMA initialization from the la= te_initcall to > > > > > > late_initcall_sync does not miss any measurement records. Howev= er, as=20 > > > > > > previously > > > > > > mentioned, Linux running in a PowerVM LPAR the move would drop = ~30 measurement > > > > > > records[1]. So no, only if the TPM is not initialized by late_= initcall, should > > > > > > IMA retry at late_initcall_sync. > > > > >=20 > > > > > What do you do in the PowerVM LPAR when the TPM is not avaiable a= t > > > > > late initcall and you have to defer IMA initialization until > > > > > late-sync? > > > >=20 > > > > Your question is hypothetical ... > > >=20 > > > > > >=20 > > > > ... as the TPM isn't deferred, so IMA doesn't go into > > > > TPM-bypass mode. Testing on a PowerVM LPAR demonstrated that it sk= ips ~30 > > > > measurement list records. So moving the initcall to late_initcall_= sync would > > > > cause a regression. > > >=20 > > > Let me rephrase to make the question clear - how do you plan to handl= e a=20 > > > system where you lose measurements by waiting until late-sync, but th= e TPM=20 > > > is not available at the late initcall. > >=20 > > There have been suggestions to queue the IMA measurements, but that goe= s against > > the "measure before use" principle. The solution is not to defer IMA > > initialization for all systems, but to differentiate the boot_aggregate= record > > (boot_aggregate vs. boot_aggregate_late) based on when the TPM becomes = available > > relative to IMA's initcall. IMA's job is simply to collect and provide= the > > measurement list. Based on the attestation service policy, the attesta= tion > > service will decide whether a measurement list containing boot_aggregat= e_late is > > acceptable. >=20 > Agreed on no violation of the measure and load principle. >=20 > But also the two boot_aggregate solution does not work. If there are > measurements before boot_aggregate_late, they can corrupt the system > without noticing, and the corrupted system would emit the > boot_aggregate measurement (non-late) to pass verification. This is a risk management issue. The conservative option is to continue initializing IMA only at late_initcall, as we have been doing, and accept t= he late TPM initialization limitation. The alternative is to also allow IMA to initialize at late_initcall_sync, controlled by a Kconfig option, so that existing systems are unaffected while systems with late TPM initialization = can opt in to boot_aggregate_late support. Mimi