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Fri, 18 Apr 2025 03:37:21 -0400 X-MC-Unique: IWoL9Hl0OVOTip_iF6TP0Q-1 X-Mimecast-MFC-AGG-ID: IWoL9Hl0OVOTip_iF6TP0Q_1744961839 Received: from mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.15]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 57FA11955DC5; Fri, 18 Apr 2025 07:37:18 +0000 (UTC) Received: from localhost (unknown [10.72.112.33]) by mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 6B8741956095; Fri, 18 Apr 2025 07:37:15 +0000 (UTC) Date: Fri, 18 Apr 2025 15:37:11 +0800 From: Baoquan He To: steven chen Cc: zohar@linux.ibm.com, stefanb@linux.ibm.com, roberto.sassu@huaweicloud.com, roberto.sassu@huawei.com, eric.snowberg@oracle.com, ebiederm@xmission.com, paul@paul-moore.com, code@tyhicks.com, bauermann@kolabnow.com, linux-integrity@vger.kernel.org, kexec@lists.infradead.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, madvenka@linux.microsoft.com, nramas@linux.microsoft.com, James.Bottomley@hansenpartnership.com, vgoyal@redhat.com, dyoung@redhat.com Subject: Re: [PATCH v12 4/9] ima: kexec: skip IMA segment validation after kexec soft reboot Message-ID: References: <20250416021028.1403-1-chenste@linux.microsoft.com> <20250416021028.1403-5-chenste@linux.microsoft.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250416021028.1403-5-chenste@linux.microsoft.com> X-Scanned-By: MIMEDefang 3.0 on 10.30.177.15 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250418_003727_675598_B71E90BA X-CRM114-Status: GOOD ( 31.72 ) X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "kexec" Errors-To: kexec-bounces+kexec=archiver.kernel.org@lists.infradead.org On 04/15/25 at 07:10pm, steven chen wrote: > From: Steven Chen > > Currently, the function kexec_calculate_store_digests() calculates and > stores the digest of the segment during the kexec_file_load syscall, > where the IMA segment is also allocated. > > Later, the IMA segment will be updated with the measurement log at the > kexec execute stage when a kexec reboot is initiated. Therefore, the > digests should be updated for the IMA segment in the normal case. The > problem is that the content of memory segments carried over to the new > kernel during the kexec systemcall can be changed at kexec 'execute' > stage, but the size and the location of the memory segments cannot be > changed at kexec 'execute' stage. > > To address this, skip the calculation and storage of the digest for the > IMA segment in kexec_calculate_store_digests() so that it is not added > to the purgatory_sha_regions. > > With this change, the IMA segment is not included in the digest > calculation, storage, and verification. > > Cc: Eric Biederman > Cc: Baoquan He > Cc: Vivek Goyal > Cc: Dave Young > Signed-off-by: Tushar Sugandhi > Signed-off-by: Steven Chen You may need to set tags as below for this patch: Co-developed-by: Tushar Sugandhi Signed-off-by: Tushar Sugandhi Signed-off-by: Steven Chen =======Quoted from Documentation/process/5.Posting.rst===== - Co-developed-by: states that the patch was co-created by several developers; it is a used to give attribution to co-authors (in addition to the author attributed by the From: tag) when multiple people work on a single patch. Every Co-developed-by: must be immediately followed by a Signed-off-by: of the associated co-author. Details and examples can be found in :ref:`Documentation/process/submitting-patches.rst `. ======== Other than this nit, this looks good to me: Acked-by: Baoquan He > --- > include/linux/kexec.h | 3 +++ > kernel/kexec_file.c | 22 ++++++++++++++++++++++ > security/integrity/ima/ima_kexec.c | 3 +++ > 3 files changed, 28 insertions(+) > > diff --git a/include/linux/kexec.h b/include/linux/kexec.h > index 7d6b12f8b8d0..107e726f2ef3 100644 > --- a/include/linux/kexec.h > +++ b/include/linux/kexec.h > @@ -362,6 +362,9 @@ struct kimage { > > phys_addr_t ima_buffer_addr; > size_t ima_buffer_size; > + > + unsigned long ima_segment_index; > + bool is_ima_segment_index_set; > #endif > > /* Core ELF header buffer */ > diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c > index 3eedb8c226ad..606132253c79 100644 > --- a/kernel/kexec_file.c > +++ b/kernel/kexec_file.c > @@ -38,6 +38,21 @@ void set_kexec_sig_enforced(void) > } > #endif > > +#ifdef CONFIG_IMA_KEXEC > +static bool check_ima_segment_index(struct kimage *image, int i) > +{ > + if (image->is_ima_segment_index_set && i == image->ima_segment_index) > + return true; > + else > + return false; > +} > +#else > +static bool check_ima_segment_index(struct kimage *image, int i) > +{ > + return false; > +} > +#endif > + > static int kexec_calculate_store_digests(struct kimage *image); > > /* Maximum size in bytes for kernel/initrd files. */ > @@ -764,6 +779,13 @@ static int kexec_calculate_store_digests(struct kimage *image) > if (ksegment->kbuf == pi->purgatory_buf) > continue; > > + /* > + * Skip the segment if ima_segment_index is set and matches > + * the current index > + */ > + if (check_ima_segment_index(image, i)) > + continue; > + > ret = crypto_shash_update(desc, ksegment->kbuf, > ksegment->bufsz); > if (ret) > diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c > index b12ac3619b8f..7e0a19c3483f 100644 > --- a/security/integrity/ima/ima_kexec.c > +++ b/security/integrity/ima/ima_kexec.c > @@ -145,6 +145,7 @@ void ima_add_kexec_buffer(struct kimage *image) > kbuf.buffer = kexec_buffer; > kbuf.bufsz = kexec_buffer_size; > kbuf.memsz = kexec_segment_size; > + image->is_ima_segment_index_set = false; > ret = kexec_add_buffer(&kbuf); > if (ret) { > pr_err("Error passing over kexec measurement buffer.\n"); > @@ -155,6 +156,8 @@ void ima_add_kexec_buffer(struct kimage *image) > image->ima_buffer_addr = kbuf.mem; > image->ima_buffer_size = kexec_segment_size; > image->ima_buffer = kexec_buffer; > + image->ima_segment_index = image->nr_segments - 1; > + image->is_ima_segment_index_set = true; > > kexec_dprintk("kexec measurement buffer for the loaded kernel at 0x%lx.\n", > kbuf.mem); > -- > 2.43.0 >