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 B654354BC0 for ; Thu, 11 Jan 2024 18:17:56 +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="RkX1TdGn" Received: from [192.168.86.69] (unknown [50.46.228.62]) by linux.microsoft.com (Postfix) with ESMTPSA id 36D8020B3CC1; Thu, 11 Jan 2024 10:17:56 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 36D8020B3CC1 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1704997076; bh=seE6BYr+cMuO0qFfh44sOOBr4O2KLpUiZvXYO2myDXA=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=RkX1TdGnmCwd7Fpw3cOxfW2QLaLgHaAQKdt6LgNOXvic6KI2SMQX89U/qSUDFbYVv OahNZFv0VCmlcHbGGKzQU8As5/owEkkx6+3yGHXwndeQE+1Z4d0G08oLrwulfF2Azi WqZfT/uSoTWoQgXvI8S0DJluLdrDH9zXlQPcVmu8= Message-ID: <97681564-5930-4604-b8b9-b208873fc05f@linux.microsoft.com> Date: Thu, 11 Jan 2024 10:17:48 -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 5/7] ima: suspend measurements during buffer copy at kexec 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> <20231216010729.2904751-6-tusharsu@linux.microsoft.com> <7ed7dccf-8482-4285-b21e-d518cb20d9e9@linux.microsoft.com> <10d5bc81db27c21613dacace9bedad345705dcea.camel@linux.ibm.com> From: Tushar Sugandhi In-Reply-To: <10d5bc81db27c21613dacace9bedad345705dcea.camel@linux.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 1/11/24 09:30, Mimi Zohar wrote: > On Fri, 2024-01-05 at 11:50 -0800, Tushar Sugandhi wrote: >> >> On 12/20/23 12:44, Mimi Zohar wrote: >>> On Fri, 2023-12-15 at 17:07 -0800, Tushar Sugandhi wrote: >>>> If the new measurements are added to the IMA log while it is being >>>> being copied to the kexec buffer during kexec 'execute', it can miss >>>> copying those new measurements to the kexec buffer, and the buffer can go >>>> out of sync with TPM PCRs. This could result in breaking the integrity >>>> of the measurements after the kexec soft reboot to the new Kernel. >>>> >>>> Add a check in the ima_add_template_entry() function not to measure >>>> events and return from the function early when 'suspend_ima_measurements' >>>> flag is set. >>>> >>>> This ensures the consistency of the IMA measurement list while copying >>>> them to the kexec buffer. When the 'suspend_ima_measurements' flag is >>>> set, any new measurements will be ignored until the flag is unset. This >>>> allows the buffer to be safely copied without worrying about concurrent >>>> modifications to the measurement list. This is crucial for maintaining >>>> the integrity of the measurements during a kexec soft reboot. >>>> >>>> Signed-off-by: Tushar Sugandhi >>>> --- >>>> security/integrity/ima/ima_queue.c | 13 +++++++++++++ >>>> 1 file changed, 13 insertions(+) >>>> >>>> diff --git a/security/integrity/ima/ima_queue.c b/security/integrity/ima/ima_queue.c >>>> index cb9abc02a304..5946a26a2849 100644 >>>> --- a/security/integrity/ima/ima_queue.c >>>> +++ b/security/integrity/ima/ima_queue.c >>>> @@ -195,6 +195,19 @@ int ima_add_template_entry(struct ima_template_entry *entry, int violation, >>>> } >>>> } >>>> >>>> + /* >>>> + * suspend_ima_measurements will be set if the system is >>>> + * undergoing kexec soft boot to a new kernel. >>>> + * suspending measurements in this short window ensures the >>>> + * consistency of the IMA measurement list during copying >>>> + * of the kexec buffer. >>>> + */ >>>> + if (atomic_read(&suspend_ima_measurements)) { >>>> + audit_cause = "measurements_suspended"; >>>> + audit_info = 0; >>>> + goto out; >>>> + } >>>> + >>>> result = ima_add_digest_entry(entry, >>>> !IS_ENABLED(CONFIG_IMA_DISABLE_HTABLE)); >>>> if (result < 0) { >>> >>> I assume you meant to include the suspend/resume code in "ima: kexec: >>> move ima log copy from kexec load to execute" in this patch. >>> >> >> Sure, I can move the suspend/resume code from Patch 2/7 of this series >> to this patch (5/7). >> >> Earlier I introduced the suspend/resume functionality in patch 2 because >> it was used in the functions in that patch. >> >> But shifting it hear will make the patches cleaner. > > Just a reminder this isn't the only issued mentioned in 2/7. Please refer to it > for the other comments (e.g. make not including/verifying the IMA segment hash a > separate patch). > > Before reposting, please remember to test after applying each patch in the patch > set to ensure that the measurement list is properly carried across kexec. Yes, I had read your responses on patch 2/7. I have been meaning to respond to you on 2/7, but I kept getting distracted by some other work-items on my plate. Really sorry :( I will respond to your comments on 2/7 by end of the day, and incorporate the feedback before reposting.