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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <87v9knpa36.fsf@morokweng.localdomain> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200531_210547_236106_B9E859E2 X-CRM114-Status: GOOD ( 23.39 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , kstewart@linuxfoundation.org, gregkh@linuxfoundation.org, benh@kernel.crashing.org, bhsharma@redhat.com, tao.li@vivo.com, zohar@linux.ibm.com, paulus@samba.org, vincenzo.frascino@arm.com, will@kernel.org, Rob Herring , nramas@linux.microsoft.com, frowand.list@gmail.com, masahiroy@kernel.org, jmorris@namei.org, takahiro.akashi@linaro.org, linux-arm-kernel@lists.infradead.org, catalin.marinas@arm.com, serge@hallyn.com, devicetree@vger.kernel.org, pasha.tatashin@soleen.com, hsinyi@chromium.org, tusharsu@linux.microsoft.com, tglx@linutronix.de, allison@lohutok.net, christophe.leroy@c-s.fr, mbrugger@suse.com, balajib@linux.microsoft.com, dmitry.kasatkin@gmail.com, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, james.morse@arm.com, mpe@ellerman.id.au, linux-integrity@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 5/22/20 9:08 PM, Thiago Jung Bauermann wrote: > > Hello Prakhar, > > Prakhar Srivastava writes: > >> On 5/12/20 4:05 PM, Rob Herring wrote: >>> On Wed, May 06, 2020 at 10:50:04PM -0700, Prakhar Srivastava wrote: >>>> Hi Mark, >>> >>> Please don't top post. >>> >>>> This patch set currently only address the Pure DT implementation. >>>> EFI and ACPI implementations will be posted in subsequent patchsets. >>>> >>>> The logs are intended to be carried over the kexec and once read the >>>> logs are no longer needed and in prior conversation with James( >>>> https://lore.kernel.org/linux-arm-kernel/0053eb68-0905-4679-c97a-00c5cb6f1abb@arm.com/) >>>> the apporach of using a chosen node doesn't >>>> support the case. >>>> >>>> The DT entries make the reservation permanent and thus doesnt need kernel >>>> segments to be used for this, however using a chosen-node with >>>> reserved memory only changes the node information but memory still is >>>> reserved via reserved-memory section. >>> >>> I think Mark's point was whether it needs to be permanent. We don't >>> hardcode the initrd address for example. >>> >> Thankyou for clarifying my misunderstanding, i am modelling this keeping to the >> TPM log implementation that uses a reserved memory. I will rev up the version >> with chosen-node support. >> That will make the memory reservation free after use. > > Nice. Do you intend to use the same property that powerpc uses > (linux,ima-kexec-buffer)? > I was naming it ima-buffer, but naming is not a huge concern. I will use linux,ima-kexec-buffer. >>>> On 5/5/20 2:59 AM, Mark Rutland wrote: >>>>> Hi Prakhar, >>>>> >>>>> On Mon, May 04, 2020 at 01:38:27PM -0700, Prakhar Srivastava wrote: >>>>>> IMA during kexec(kexec file load) verifies the kernel signature and measures >>> >>> What's IMAIMA is a LSM attempting to detect if files have been accidentally or >> maliciously altered, both remotely and locally, it can also be used >> to appraise a file's measurement against a "good" value stored as an extended >> attribute, and enforce local file integrity. >> >> IMA also validates and measures the signers of the kernel and initrd >> during kexec. The measurements are extended to PCR 10(configurable) and the logs >> stored in memory, however once kexec'd the logs are lost. Kexec is used as >> secondary boot loader in may use cases and loosing the signer >> creates a security hole. >> >> This patch is an implementation to carry over the logs and making it >> possible to remotely validate the signers of the kernel and initrd. Such a >> support exits only in powerpc. >> This patch makes the carry over of logs architecture independent and puts the >> complexity in a driver. > > If I'm not mistaken, the code at arch/powerpc/kexec/ima.c isn't actually > powerpc-specific. It could be moved to an arch-independent directory and > used by any other architecture which supports device trees. > > I think that's the simplest way forward. And to be honest I'm still > trying to understand why you didn't take that approach. Did you try it > and hit some obstacle or noticed a disadvantage for your use case? > The approach i have in this patch set is to provide an abstraction layer that can be called from any architecture. However taking a deeper look only the setup dtb is probably architecture specific, only because the architecture specific kexec sets up the device tree. I can also move the code up in security/ima. However i do have some concerns with layering. I am hoping you can provide me with some guidance in this aspect, i will send you the patch i am working on to get some early feedback. Thanks, Prakhar Srivastava > -- > Thiago Jung Bauermann > IBM Linux Technology Center > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel