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 A5E3A22D4CD; Fri, 21 Mar 2025 16:46:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=13.77.154.182 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742575609; cv=none; b=oyC6yFg/4LrWQtUjf+ljFhudibenw4npjBN3FIyomsagJ7pHfh303jhgBGvhQ0VqOdMojrRnHCILQ7pPLH6z4KUbFjQisoLHJt1ATx0DsblcWPasAtGVm6Tf9aEvZdQ/Yv0/ZfO5c/W0o5kuxbT6FbqpORvxlD9RcwZbxgMDkcQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742575609; c=relaxed/simple; bh=eEbvZnqrnx+iFFTjfr8LLlmdZJB48dPCOL4dCsjSVpg=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=oB0zvO4lPYBTO+BmXMZQZ7qR+URUNhyJE0lbucsK5SJeMHIzr+WXwcG9MOm7mr645jhJ9MYUBo0mZqPQxznew9IQ6uCIUx6uY69BuiRJzEG8B7w7U5ajc+nX7zMCi7kSJOQpiU0MKPOJK79q52g/ThTewe8kzP4w+5wHbq2AgGc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com; spf=pass smtp.mailfrom=linux.microsoft.com; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b=N9QOP+Ix; arc=none smtp.client-ip=13.77.154.182 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="N9QOP+Ix" Received: from [10.17.64.97] (unknown [131.107.174.225]) by linux.microsoft.com (Postfix) with ESMTPSA id E44CC202538A; Fri, 21 Mar 2025 09:46:46 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com E44CC202538A DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1742575607; bh=nSvjsrtvsYH0Ut5RuXHshDg+2Of7/6QpJwrxhRT3jP0=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=N9QOP+IxLavnYNz3HjFdNVhXARehD6rMEeIKlMfzV30fLZ18gZbKafDdW6lpavtKj 9lCPhW7bRpf0k84LU5RZMQ+izAFR/wJqqLapseL5CO+fGtFaWf2Q8KZ4cRx9ZYESsb iBKjV0fTVKuBXQZYXx4q+MftjeIboA0uvV+k59p8= Message-ID: Date: Fri, 21 Mar 2025 09:46:47 -0700 Precedence: bulk X-Mailing-List: linux-security-module@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v10 7/8] ima: make the kexec extra memory configurable To: Baoquan He 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 References: <20250318010448.954-1-chenste@linux.microsoft.com> <20250318010448.954-8-chenste@linux.microsoft.com> Content-Language: en-US From: steven chen In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 3/19/2025 7:52 PM, Baoquan He wrote: > On 03/17/25 at 06:04pm, steven chen wrote: >> The extra memory allocated for carrying the IMA measurement list across >> kexec is hard-coded as half a PAGE. Make it configurable. >> >> Define a Kconfig option, IMA_KEXEC_EXTRA_MEMORY_KB, to configure the >> extra memory (in kb) to be allocated for IMA measurements added during >> kexec soft reboot. Ensure the default value of the option is set such >> that extra half a page of memory for additional measurements is allocated >> for the additional measurements. >> >> Update ima_add_kexec_buffer() function to allocate memory based on the >> Kconfig option value, rather than the currently hard-coded one. >> >> Suggested-by: Stefan Berger >> Signed-off-by: Tushar Sugandhi >> Signed-off-by: steven chen >> Reviewed-by: Stefan Berger >> Reviewed-by: Mimi Zohar >> --- >> security/integrity/ima/Kconfig | 10 ++++++++++ >> security/integrity/ima/ima_kexec.c | 16 +++++++++++----- >> 2 files changed, 21 insertions(+), 5 deletions(-) >> >> diff --git a/security/integrity/ima/Kconfig b/security/integrity/ima/Kconfig >> index 475c32615006..d73c96c3c1c9 100644 >> --- a/security/integrity/ima/Kconfig >> +++ b/security/integrity/ima/Kconfig >> @@ -321,4 +321,14 @@ config IMA_DISABLE_HTABLE >> help >> This option disables htable to allow measurement of duplicate records. >> >> +config IMA_KEXEC_EXTRA_MEMORY_KB >> + int "Extra memory for IMA measurements added during kexec soft reboot" >> + depends on IMA_KEXEC >> + default 0 > Is there range for this memory, e.g [0, max] and max will be a value > according to our current perception? Hi Baoquan, In the code below there is value check for this if ((kexec_segment_size == ULONG_MAX) || ((kexec_segment_size >> PAGE_SHIFT) > totalram_pages() / 2)) { Hi Mimi, Could you provide any guidance if we need to set the range? Thanks, Steven >> + help >> + IMA_KEXEC_EXTRA_MEMORY_KB determines the extra memory to be >> + allocated (in kb) for IMA measurements added during kexec soft reboot. >> + If set to the default value of 0, an extra half page of memory for those >> + additional measurements will be allocated. >> + >> endif >> diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c >> index c390c745f882..0f214e41dd33 100644 >> --- a/security/integrity/ima/ima_kexec.c >> +++ b/security/integrity/ima/ima_kexec.c >> @@ -131,6 +131,7 @@ void ima_add_kexec_buffer(struct kimage *image) >> .buf_min = 0, .buf_max = ULONG_MAX, >> .top_down = true }; >> unsigned long binary_runtime_size; >> + unsigned long extra_memory; >> >> /* use more understandable variable names than defined in kbuf */ >> size_t kexec_buffer_size = 0; >> @@ -138,15 +139,20 @@ void ima_add_kexec_buffer(struct kimage *image) >> int ret; >> >> /* >> - * Reserve an extra half page of memory for additional measurements >> - * added during the kexec load. >> + * Reserve extra memory for measurements added during kexec. >> */ >> - binary_runtime_size = ima_get_binary_runtime_size(); >> + if (CONFIG_IMA_KEXEC_EXTRA_MEMORY_KB <= 0) >> + extra_memory = PAGE_SIZE / 2; >> + else >> + extra_memory = CONFIG_IMA_KEXEC_EXTRA_MEMORY_KB * 1024; >> + >> + binary_runtime_size = ima_get_binary_runtime_size() + extra_memory; >> + >> if (binary_runtime_size >= ULONG_MAX - PAGE_SIZE) >> kexec_segment_size = ULONG_MAX; >> else >> - kexec_segment_size = ALIGN(ima_get_binary_runtime_size() + >> - PAGE_SIZE / 2, PAGE_SIZE); >> + kexec_segment_size = ALIGN(binary_runtime_size, PAGE_SIZE); >> + >> if ((kexec_segment_size == ULONG_MAX) || >> ((kexec_segment_size >> PAGE_SHIFT) > totalram_pages() / 2)) { >> pr_err("Binary measurement list too large.\n"); >> -- >> 2.25.1 >> >>