From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by smtp.subspace.kernel.org (Postfix) with ESMTP id A185F17540 for ; Fri, 12 Jan 2024 17:26:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="NNjnAYa7" Received: from [192.168.86.69] (unknown [50.46.228.62]) by linux.microsoft.com (Postfix) with ESMTPSA id DC05820B3CE1; Fri, 12 Jan 2024 09:26:15 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com DC05820B3CE1 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1705080376; bh=KbxatyazcGOb5nVqjoWrzE226sOvTe/q3xt20G4j/YQ=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=NNjnAYa7dcmhzXN7wy7JcWFS/2uApgDBtTWnXOtv+Q8Hxtkf8v3wL+QrK6p7iHJYR 68TBJoI8PALpcCVnvowTMykrVzELltaSIcSUp632A8ZSmvs3ji1xUZJNPgHB0FbyGJ LeMkB9++4X88Gfj4MeZh/KIH2yv/V9uNaTdCIpE0= Message-ID: <30910120-2a44-46fd-b8d3-c7bff38b6269@linux.microsoft.com> Date: Fri, 12 Jan 2024 09:26:15 -0800 Precedence: bulk X-Mailing-List: linux-integrity@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 2/7] ima: kexec: move ima log copy from kexec load to execute Content-Language: en-US To: Mimi Zohar , roberto.sassu@huaweicloud.com, roberto.sassu@huawei.com, eric.snowberg@oracle.com, stefanb@linux.ibm.com, ebiederm@xmission.com, noodles@fb.com, bauermann@kolabnow.com, linux-integrity@vger.kernel.org, kexec@lists.infradead.org Cc: code@tyhicks.com, nramas@linux.microsoft.com, paul@paul-moore.com References: <20231216010729.2904751-1-tusharsu@linux.microsoft.com> <20231216010729.2904751-3-tusharsu@linux.microsoft.com> <8f5deffb34c9a948a20e63eae44a1e3343e2ffe4.camel@linux.ibm.com> From: Tushar Sugandhi In-Reply-To: <8f5deffb34c9a948a20e63eae44a1e3343e2ffe4.camel@linux.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 1/12/24 09:06, Mimi Zohar wrote: > >>>> diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c >>>> index f989f5f1933b..bf758fd5062c 100644 >>>> --- a/kernel/kexec_file.c >>>> +++ b/kernel/kexec_file.c >>>> @@ -734,6 +734,14 @@ 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 (image->is_ima_segment_index_set && >>>> + i == image->ima_segment_index) >>>> + continue; >>> With this change, the IMA segment is not included in the digest >>> calculation, nor should it be included in the digest verification. >>> However, I'm not seeing the matching code change in the digest >>> verification. >>> >> Fair question. >> >> But I don't think anything else needs to be done here. >> >> The way kexec_calculate_store_digests() and verify_sha256_digest() >> are implemented, it already skips verification of the segments if >> the segment is not part of 'purgatory_sha_regions'. >> >> In kexec_calculate_store_digests(), my change is to 'continue' when the >> segment is the IMA segment when the function is going through all the >> segments in a for loop [1]. >> >> Therefore in kexec_calculate_store_digests() - >> - crypto_shash_update() is not called for IMA segment [1]. >> - sha_regions[j] is not updated with IMA segment [1]. >> - This 'sha_regions' variable later becomes 'purgatory_sha_regions' >> in kexec_calculate_store_digests [1]. >> - and verify_sha256_digest() only verifies 'purgatory_sha_regions'[2]. >> >> Since IMA segment is not part of the 'purgatory_sha_regions', it is >> not included in the verification as part of verify_sha256_digest(). >> >>> Please make ignoring the IMA segment a separate patch. >>> >> Sure. Will do. > Thank you for the explanation. Please include in the patch description a > statement about the "sha_regions" not including the IMA segment, so nothing is > needed on the verify side. Definitely. Will do.